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Tunable magnetism and spin-polarized electronic transport in graphene mediated by molecular functionalization of extended defects | Quantized alternate current on curved graphene | The Mediatorless Electroanalytical Sensing of Sulfide Utilizing Unmodified Graphitic Electrode Materials | eng_Latn | 11,600 |
The generation of nanostructured particles in high-temperature flames is important both for the control of emissions from combustion devices and for the synthesis of high-value chemicals for a variety of applications. The physiochemical processes that lead to the production of fine particles in turbulent flames are highly sensitive to the flow physics and, in particular, the history of thermochemical compositions and turbulent features they encounter. Consequently, it is possible to change the characteristic size, structure, composition, and yield of the fine particles by altering the flow configuration. This review describes the complex multiscale interactions among turbulent fluid flow, gas-phase chemical reactions, and solid-phase particle evolution. The focus is on modeling the generation of soot particles, an unwanted pollutant from automobile and aircraft engines, as well as metal oxides, a class of high-value chemicals sought for specialized applications, including emissions control. Issues arising due to the numerical methods used to approximate the particle number density function, the modeling of turbulence-chemistry interactions, and model validation are also discussed. | Flame synthesis represents a viable technique for large-scale production of titanium dioxide (TiO2) nanoparticles. A key ingredient in the modeling of this process is the description of the chemical kinetics, which include Ti oxidation, hydrocarbon fuel combustion, and chlorination. While detailed chemical mechanisms have been developed for predicting TiO2 nanoparticle properties by West et al. (e.g., Combust. Flame 2009, 156, 1764), their use in turbulent reacting flow simulations is limited to very simple configurations or requires significant modeling assumptions to bring their computational cost down to an acceptable level. In this work, a reduced kinetic scheme describing the oxidation of TiCl4 in a methane flame is derived from and validated against the predictions of a detailed mechanism from the literature. The reduction procedure uses graph-based methods for unimportant kinetic pathways elimination and quasi-steady-state species selection. Reduction targets are chosen in accordance with previous ... | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,601 |
The paper studies the impact of gaseous water on the stability of micron aluminum powders in time at room temperature using the method of gravimetric analysis. The stability was studied using methods of thermal analysis during heating up to 1200 °С in air. The composition of products was analyzed using X-ray diffraction analysis. It was found out that the stability of micron aluminum powders depends on partial pressure of water vapor: the increase of pressure results in decreased stability of powders. The work gives recommendations for storing micron aluminum powders. | For testing the determination of the reactivity of aluminum powders it is proposed to use the following parameters: temperature of the beginning of oxidation, maximal oxidation rate, degree of transformation (degree of oxidation) of aluminum, relative thermal effect. Parameters for an evaluation of the reactivity of powders were chosen following the analysis of results of a non-isothermal oxidation of powders of different grain size under conditions of programmed heating (the oxidizer being air). According to the proposed method of testing, the sample of ultrafine powder UFAP-4 produced by the electrical explosion of wires has the highest reactivity among the studied powders. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,602 |
By making use of the induced transformation of graphite oxide (GO) to laser scribed graphene (LSG), the coated layers of GO/carbon nanotubes (CNTs) hybrid powders on flexible polyethylene terephthalate sheets were patterned into LSG/CNTs micro-supercapacitors (LSG/CNTs-MSCs). In the presence of CNTs with a smaller diameter, the laser-scribed LSG/CNTs-MSC was found to yield the better energy storage performance. This dependence on the CNT diameter can be attributed to the role of CNTs in prevention of restacking of LSG layers and thus the increase of ion-accessible surface area. The CNTs with a smaller diameter can be more easily inserted between the LSG layers, thus inhibiting the restacking phenomenon more effectively. By using the single-wall CNTs (SWCNTs) of 1–2 nm diameter, the laser-scribed LSG/SWCNTs-MSC was observed to exhibit the best electrochemical properties: The volumetric capacitance of 3.10 F cm −3 at a current density of 1000 mA cm −3 , the volumetric energy density of 0.84 mW h cm −3 and power density of 1.0 W cm −3 , and long-term cycling stability. | Laser reduction of graphene oxide is a promising technology for manufacturing advanced devices such as supercapacitors, sensors and transistors, owing to its distinctive advantages in selective and localized GO reduction, direct micro-nanoscale patterning, and no requirement for chemicals. However, the fundamental mechanism underlying the laser induced reduction is still not well understood. In this paper, we demonstrate that by adjusting the power and scanning speed of a 780 nm femtosecond laser, not only can one distinguish, but also effectively tune, two coexisting sub-processes during the laser reduction, namely the direct conversion from sp3 to sp2 carbon and removal of oxygen functional groups. Different oxygen containing groups demonstrate varied degrees of reduction when the power of the laser was varied. Our study provides solid and direct evidence for the coexistence of two sub-processes in the laser induced reduction of graphene oxide, which is essential for both mechanistic understanding and practical adoption of this technique in real word applications. | MLL1 regulates circadian promoters by depositing H3K4 trimethyl marks, whose levels are also modulated by the NAD+-dependent deacetylase SIRT1. SIRT1 is now shown to promote circadian deacetylation of MLL1, thus affecting MLL1's methyltransferase activity. | eng_Latn | 11,603 |
The research project 'An Evaluation of Transformational Change in NHS North East' examines the progress and success of National Health Service (NHS) organisations in north east England in implementing and embedding the North East Transformation System (NETS), a region-wide programme to improve healthcare quality and safety, and to reduce waste, using a combination of Vision, Compact, and Lean-based Method. This paper concentrates on findings concerning the role of leadership in enabling tranformational change, based on semi-structured interviews with a mix of senior NHS managers and quality improvement staff in 14 study sites. Most interviewees felt that implementing the NETS requires committed, stable leadership, attention to team-building across disciplines and leadership development at many levels. We conclude that without senior leader commitment to continuous improvement over a long time scale and serious efforts to distribute leadership tasks to all levels, healthcare organisations are less likely to achieve positive changes in managerial-clinical relations, sustainable improvements to organisational culture and, ultimately, the region-wide step change in quality, safety and efficiency that the NETS was designed to deliver. | Objective ::: To test the effectiveness of a Bayesian model employing subjective probability estimates for predicting success and failure of health care improvement projects. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,604 |
It is well known and well established by scientific observation that a free neutron radioactively decays into a proton plus an electron plus an anti-neutrino with a mean life time before decay of about 900 seconds. ::: That established fact conflicts sharply with the hypothesis that the neutron is composed of two down plus one up quark and that the proton is composed of one down plus two up quarks. ::: That conflict throws doubt on the entire quark hypothesis. | The rest mass of the neutron is exactly equal to the rest mass of a proton plus that of an electron plus the mass equivalent of the kinetic energy of those two particles after they have electrostatically accelerated from very far apart toward each other to a separation distance of a proton diameter. That fact is either a remarkable coincidence or evidence that the neutron is a combination of a proton and an electron. The calculation of this sheds new light on the nature and significance of the Lamb Shift. Roger Ellman, The-Origin Foundation, Inc. 320 Gemma Circle, Santa Rosa, CA 95404, USA [email protected] http://www.The-Origin.org | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,605 |
The key features of the complete, stable nickel—carbon phase diagram have been established at pressures up to 54 kbar, and these features have been directly related to the nucleation and growth characteristics of diamonds in this system. At pressures in excess of 52.5 kbar, a liquid+graphite+diamond eutectic is formed at approximately 0.3 at. % nickel which results in an effective displacement of the diamond—graphite equilibrium line. This displacement is shown to be of considerable importance in the nucleation and growth of diamonds in this system. Under low and moderate driving forces, the rate‐controlling mechanism in the growth on a speed diamond is the diffusion of carbon across the molten metal film surrounding the diamond. The observed diffusion coefficients at 54 kbar and 1660°<T<1800°K lie in the range: 2×10−5<D<4×10−5 cm2/sec.The key features of the complete, stable nickel—carbon phase diagram have been established at pressures up to 54 kbar, and these features have been directly related to the nucleation and growth characteristics of diamonds in this system. At pressures in excess of 52.5 kbar, a liquid+graphite+diamond eutectic is formed at approximately 0.3 at. % nickel which results in an effective displacement of the diamond—graphite equilibrium line. This displacement is shown to be of considerable importance in the nucleation and growth of diamonds in this system. Under low and moderate driving forces, the rate‐controlling mechanism in the growth on a speed diamond is the diffusion of carbon across the molten metal film surrounding the diamond. The observed diffusion coefficients at 54 kbar and 1660°<T<1800°K lie in the range: 2×10−5<D<4×10−5 cm2/sec. | High quality cubic diamond crystals were grown using the temperature gradient method at high pressure and high temperature (HPHT), in a new FeNi alloy as solvent. The crystals were grown at relatively low temperatures suitable for the growth of {100} faces. An increase in the radial growth rate, and inhibition of the axial growth caused the growth of large, high quality cubic diamond single crystals at high growth rates. For example, over 33 h, the radial growth rate was 0.22 mm/h, while the axial growth rate was only 0.08 mm/h; the growth rate by weight was also increased to 7.3 mg/h. The yellow color of our crystal samples was more uniform than samples from Sumitomo Corporation of Japan and Element Six Corp. The Raman FWHW of the 1332 cm−1 peak in our diamond sample was smaller than the Element Six Corp. sample, but larger than that of the Sumitomo Corp. sample. The nitrogen content of our diamond samples was 240 ppm, which was much higher than the Sumitomo and Element Six samples because of the higher growth rate of our diamond samples. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,606 |
A procedure is presented for investigating entanglement loss in polymer liquids during steady-shear flow. The method combines steady shearing with small-amplitude step strain measurements to determine the elastic modulus Ge of an entangled polymer network under steady-state flow conditions. In this study, superimposed step/steady-shear measurements are used to investigate entanglement loss in narrow molecular weight distribution polystyrene/diethyl phthalate solutions with variable entanglement density (9 < N/Ne < 58). For all materials studied, Ge decreases with increasing shear rate γ over a wide range of rates. At high shear rates, an approximate scaling relation Ge(γ)∼γ−1/2 can be defined for all but the most weakly entangled polymer solution; for this material, a related scaling form Ge(γ)∼γ−1 correctly describes the experimental results. We also find that the ratio of limiting shear modulus Ge(0) to modulus at finite rate Ge(γ) is related to a molecular stretching functional 〈|E⋅u|〉 by Ge(0)/G... | Non-reversing and reversing double-step strain flows on concentrated entangled polystyrene in diethyl phthalate or tricresyl phosphate were employed to characterize transient entanglement properties affecting subsequent chain stretch and relaxation. An extended Doi-Edwards tube theory for double-step strain flows was employed to retrieve the phenomenological stretch relaxation function following a second large probe strain imposed on specially selected time scales that permit a direct assessment of the modified chain stretch with varying transient entanglement structure. Compared with single-step strain result, the maximum mean-square segmental stretch was noted to reduce by as much as 33% and 48% for non-reversing and reversing flows, respectively, with a probe strain γ2=7. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,607 |
Vanadium nitride and nitrogen-doped graphene nanosheet (G) hybrid materials were prepared by a facile sol–gel method combined with a thermal treatment at 800 °C under ammonia atmosphere. It was found that VN nanoparticles adhered to the surface of nitrogen-doped graphene nanosheets and/or were embedded in the graphene layers of the hybrid material (VN-G). This nanostructured material promises an efficient electronic and ionic conducting network, which exhibits dramatically increased specific capacities after rate capability test in comparison to the original value under the same current density. The most probable explanations for these distinct characteristics are deduced from observations by advanced transmission electron microscopy together with X-ray diffraction and electron energy-loss spectroscopy, which illustrate a gradual activation of nitride during lithiation/delithiation processes, owing to slow kinetics of VN reaction with lithium. The electrochemical results demonstrate that the weight ratio of VN to G has a significant effect on the performance and related kinetics of the materials. | Red phosphorus (RP) is considered to be one of the promising anode materials for lithium-ion batteries (LIBs) on account of its high theoretical capacity (2596 mAh g−1), abundant resources, and environmental friendliness. However, the intrinsic insulating nature and large volume change during lithium insertion/extraction process lead to drastic capacity loss upon cycling. Recently, great attention has been devoted to constructing P-based composites via mixing with carbon materials. Here, a novel P/C composite, in which red P nanoparticles were homogeneously distributed in cigarette filter-derived porous carbon (CPC), was fabricated by vaporization-condensation method. Due to the unique characteristics of porous carbon, including high specific area, good conductivity, and rich internal porous structure, CPC obtained by means of heat treatment that serves as conductive matrix to load red P could be of great benefits, which can not only improve the overall electrical conductivity but also mitigate the volume expansion issues. As a result, the RP/CPC composite as an anode material for LIBs delivers a good cycling stability (500 mAh g−1 at 100 mA g−1 with a high Coulombic efficiency above 99% after 50 cycles) and rate capability (355 mAh g−1 even at 1000 mA g−1). | The self-healing mechanism of radiation-induced defects in nickel–graphene nanocomposite is investigated by atomistic simulations. Compared with pure nickel, nickel–graphene nanocomposite has less defects remained in the bulk region after collision cascades, illustrating self-healing performance. Nickel–graphene interfaces (NGIs) serve as sinks for radiation-induced defects and preferentially trap interstitials over vacancies. Energetic and kinetic calculations reveal that the defect formation energy and diffusion barrier are reduced in the vicinity of NGIs, and the reduction are pronounced for interstitials. When NGIs are loaded with interstitials, their segregation ability on radiation-induced defects improves significantly, and the radiation-induced defects near the NGIs diffuse more easily. Especially, the vacancies (or interstitials) near the NGIs tend to annihilate (or aggregate) with the interstitials trapped at the NGIs, which only happens at the interstitial-loaded side of NGIs. Therefore, nickel–graphene nanocomposite exhibits excellent radiation tolerance and shows promise as a structural material for advanced nuclear reactors due to its NGIs with the energetic and kinetic driving forces acting on radiation-induced defects. | eng_Latn | 11,608 |
Ni-YSZ (nickel - yttria stabilized zirconia) is a material widely used for electrodes and supports in solid oxide electrochemical cells. The mechanical and electrochemical performance of these layers, and thus the whole cell, depends on their microstructure. During the initial operation of a cell, NiO is reduced to Ni. When this process is conducted under external load, like also present in a stack assembly, significant deformations of NiO/Ni-YSZ composite samples are observed. The observed creep is orders of magnitude larger than the one observed after reduction during operation. This phenomenon is referred to as accelerated creep and is expected to have a significant influence on the microstructure development and stress field present in the Ni-YSZ in solid oxide electrochemical cells (SOCs), which is highly important for the durability of the SOC. In this work we present energy selective neutron imaging studies of the accelerated creep phenomenon in Ni/NiO-YSZ composite during reduction and also during oxidation. This approach allowed us to observe the phase transition and the creep behavior simultaneously in-situ under SOC operation-like conditions. | The BOA beamline at the Swiss spallation neutron source SINQ at Paul Scherrer Institut is a flexible instrument used mainly for testing novel techniques and devices for neutron scattering and optics, but, due to the large and relatively homogeneous field of view, it can be successfully used for experiments in the field of neutron imaging. The beamline allows also for the exploitation of advanced imaging concepts such as polarized neutron imaging and diffractive neutron imaging. In this paper we present the characterization of the BOA beamline in the light of its neutron imaging capabilities. We show also the different techniques that can be employed there as user-friendly plugins for non-standard neutron imaging experiments. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,609 |
This paper is focused on how the spectroscopic properties of conjugated polymers evolve in the size range between single polymer chains and the bulk material. The measurements used single-particle spectroscopy techniques and include both static and dynamic measurements. The main observation of this work is that the spectroscopic properties of MEH-PPV evolve rapidly as a function of nanoparticle size and achieve bulk-like properties for nanoparticles greater than 10 nm in size. Nanoparticles were assembled by a reprecipitation technique and characterized by fluorescence emission spectroscopy. The physical origin of the size-dependent spectroscopic properties is assigned to the distance dependence of four main processes: electronic energy transfer between blue and red sites, triplet−triplet annihilation, singlet exciton quenching by triplets, and singlet exciton quenching by hole polarons. | Despite intense, long-term interest in organic semiconductors from both an applied and fundamental perspective, key aspects of the electronic properties of these materials remain poorly defined. A particularly challenging problem is the molecular nature of positive charge carriers, that is, holes or oxidized species in organics. Here, the unique ability of single-molecule spectroelectrochemistry (SMS-EC) to unravel complex electrochemical process in heterogeneous media is used to study the oxidation of nanoparticles of the conjugated polymer poly(9,9-dioctylfluorene-co-benzothiadiazole). A reversible hole-injection charging process has been observed that occurs primarily by initial injection of shallow (untrapped) holes, but soon after the injection, a small fraction of the holes becomes deeply trapped. Good agreement between experimental data and simulations strongly supports the presence of deep traps in the studied nanoparticles and highlights the ability of SMS-EC to study energetics and dynamics of deep traps in organic materials at the nanoscale. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,610 |
We report here on an in situ experimental analysis of the growth processes of tin dioxide nanoparticles (with mean particle radius of less than 5nm) and the oriented attachment of these particles onto SnO2 nanobelts, used as single crystalline substrates, through electron irradiation by transmission electron microscopy. Characterization by high resolution transmission electron microscopy indicates that grain growth occurs in the solid state by a two-step process consisting of grain rotation followed by coalescence. The grain rotation is likely induced by the thermal energy provided by the electron beam. Coalescence or oriented attachment occurs preferentially on particles with similar crystallographic orientations. | Ion beam irradiation is a potential tool for phase formation and material modification as a non-equilibrium technique. Localized rise in temperature and ultra fast (∼10−12 s) dissipations of impinging energy make it an attractive tool for metastable phase formation. As a matter of fact, a major component of materials science is dominated by ion beam methods, either for synthesis of materials or for its characterization. The synthesis of nanostructures, and their modification by ion beam technique will be discussed in this review article. Formation of nanostructures using ion beam technique will be discussed first. Depending on species (e.g., mass and charge state) and energy range, there are various modes for an energetic ion to dissipate its energy. The role of the electron will also be covered in this article as a basic principle of its interaction with matter, which is same as for an ion. By using a simple reactive ion beam or electron induced deposition, a secondary phase can be nucleated by ion beam mixing techniques, either by using inert gas irradiation or reactive gas implantation on any desired substrate. Nucleation of secondary phase can also be executed by electron irradiation and direct implantation of either negative or positive ions. Post implantation annealing processes are required for the complete growth of clusters formed in most of these ion irradiation techniques. Implantation processes being inherently a non-equilibrium technique, defects always have a role to play in phase formation, amorphization, and beyond (blister formation). When implanted with large energy, even electrons, one of the lightest charged particles, also manifest these properties. Electronic and nuclear energy losses of the impinging charged particle play a crucial role in material modification. Doping a nanocluster, however, is still a controversial topic. Some light will be shed on this topic with a discussion of focused ion beam. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,611 |
Scanning electron microscopy (SEM) is a practical tool to determine the dimensions of nanometer-scale features. Conventional width measurements use arbitrary criteria, e.g., a 50 % threshold crossing, to assign feature boundaries in the measured SEM intensity profile. To estimate the errors associated with such a procedure, we have simulated secondary electron signals from a suite of line shapes consisting of 30 nm tall silicon lines with varying width, sidewall angle, and corner rounding. Four different inelastic scattering models were employed in Monte Carlo simulations of electron transport to compute secondary electron image intensity profiles for each of the shapes. The 4 models were combinations of dielectric function theory with either the single-pole approximation (SPA) or the full Penn algorithm (FPA), and either with or without Auger electron emission. Feature widths were determined either by the conventional threshold method or by the model-based library (MBL) method, which is a fit of the simulated profiles to the reference model (FPA + Auger). On the basis of these comparisons we estimate the error in the measured width of such features by the conventional procedure to be as much as several nanometers. A 1 nm difference in the size of, e.g., a nominally 10 nm transistor gate would substantially alter its electronic properties. Thus, the conventional measurements do not meet the contemporary requirements of the semiconductor industry. In contrast, MBL measurements employing models with varying accuracy differed one from another by less than 1 nm. Thus, a MBL measurement is preferable in the nanoscale domain. | We assessed two approaches for determining shell thicknesses of core–shell nanoparticles (NPs) by X-ray photoelectron spectroscopy (XPS). These assessments were based on simulations of photoelectron peak intensities for Au-core/C-shell, C-core/Au-shell, Cu-core/Al-shell, and Al-core/Cu-shell NPs with a wide range of core diameters and shell thicknesses. First, we demonstrated the validity of an empirical equation developed by Shard for determinations of shell thicknesses. Values of shell thicknesses from the Shard equation typically agreed with actual shell thicknesses to better than 10%. Second, we investigated the magnitudes of elastic-scattering effects on photoelectron peak intensities by performing a similar series of simulations with elastic scattering switched off in our simulation software. Our ratios of the C-shell 1s intensity to the Au-core 4f7/2 intensity with elastic scattering switched off were qualitatively similar to those obtained by Torelli et al. from a model that neglected elastic scat... | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,612 |
We grow high-density, aligned single wall carbon nanotube mats for use as interconnects in integrated circuits by remote plasma chemical vapor deposition from a Fe–Al2O3 thin film catalyst. We carry out extensive Raman characterization of the resulting mats, and find that this catalyst system gives rise to a broad range of nanotube diameters, with no preferential selectivity of semiconducting tubes, but with at least 1∕3 of metallic tubes. | Strong viscous behavior has been discovered in nanotube mats, as observed in boron nitride nanotube (BNNT) mats under low-amplitude dynamic flexure. The solid part of the mat (BNNTs) exhibits strong viscous character (loss tangent up to 13), strong elastic character (storage modulus up to 2.3 GPa), and strong mechanical energy dissipation ability (loss modulus up to 7.3 GPa), indicating exceptional vibration damping ability. The loss tangent of the solid part of the mat decreases with increasing solid content, while the storage and loss moduli of the solid part increases, due to the increasing difficulty for frictional sliding among the BNNTs. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 11,613 |
The size distribution of particles in dispersions is an important property that is usually measured. In many cases, however, theoretical or semi-empirical models are developed to predict these distributions. The models, none the less, come with subtle constraints that limit the regimes of their applicability. At present, there is no systematic approach for identifying these limitations, which, if ignored, can lead to serious flaws. In this work we introduce an entropy-related property of the dispersion, and demonstrate th at this property, which is intensive, and, therefore, independent of system size and configuration, can be used to pinpoint where these limitations lie. | The solutions to the kinetic equation of coagulation are reviewed particularly from the standpoint of their asymptotic behavior. The coagulation equation is studied theoretically by means of a new similarity transformation. For the case of constant collision frequency factor, the transformed spectrum function approaches a self-preserving form after a sufficiently long time, for a certain class of initial distributions. For Brownian coagulation, approximate solutions are derived in closed form for the upper and the lower end of the self-preserving spectrum, and a numerical solution is given for the whole spectrum. The result of this study indicates that the shape of the self-preserving spectrum is greatly influenced by the form of the collision frequency factor. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,614 |
The article begins with an account of prewar German work, particularly that of von Ardenne, who established the theoretical basis of a scanning electron microscope and constructed an instrument which was primarily intended to overcome chromatic aberration when relatively thick specimens were examined by transmission. Neither this microscope nor a different one built a few years later in the U. S. A. attained sufficient resolution to gain acceptance and the reasons for this are examined. The remainder of the article deals with work carried out in the Cambridge University Engineering Department over the years from 1948 to about 1965, when the first successful commercial instrument was produced. The contributions made by successive research students are explained, as are also the nonscientific factors which influenced the course of the development. | Research concerning nano-materials (metal-organic frameworks (MOFs), zeolites, mesoporous silicas, etc.) and the nano-scale, including potential barriers for the particulates to diffusion to/from is of increasing importance to the understanding of the catalytic utility of porous materials when combined with any potential super structures (such as hierarchically porous materials). However, it is difficult to characterize the structure of for example MOFs via X-ray powder diffraction because of the serious overlapping of re- flections caused by their large unit cells, and it is also difficult to directly observe the opening of surface pores using ordinary methods. Electron-microscopic methods including high-resolution scanning electron microscopy (HRSEM) have therefore become imperative for the above challenges. Here, we present the theory and practical application of recent advances such as through-the-lens detection systems, which permit a reduced landing energy and the selection of high-resolution, topographically specific emitted electrons, even from electrically insulating nano-materials. | Environmental transmission electron microscopy is recently of a great interest as well as ultra-high resolution observation using aberration correctors. This method is a kind of extension of so-called "in-situ electron microscopy" performed since the 1970's. It nowadays focuses on dynamic observation with atomic resolution in gaseous atmosphere and liquids. Since 2007, Nagoya university has developed a new 1 MV high voltage (scanning) transmission electron microscope, where nano-materials can be observed in conditions of gases, liquids and illuminating lights and mechanical operation as well as in three-dimension by using electron tomography. | eng_Latn | 11,615 |
The formation of covalent bonds to single-walled carbon nanotube (SWNT) or graphene surfaces usually leads to a decrease in the electrical conductivity and mobility as a result of the structural rehybridization of the functionalized carbon atoms from sp2 to sp3. In the present study, we explore the effect of metal deposition on semiconducting (SC-) and metallic (MT-) SWNT thin films in the vicinity of the percolation threshold and we are able to clearly delineate the effects of weak physisorption, ionic chemisorption with charge transfer, and covalent hexahapto (η6) chemisorption on these percolating networks. The results support the idea that for those metals capable of forming bis-hexahapto-bonds, the generation of covalent (η6-SWNT)M(η6-SWNT) interconnects provides a conducting pathway in the SWNT films and establishes the transition metal bis-hexahapto organometallic bond as an electronically conjugating linkage between graphene surfaces. | The continuous downward scaling in integrated circuit (IC) technologies has led to rapid shrinking of transistor and interconnect feature sizes. While scaling benefits transistors by increasing the switching speed and reducing the power consumption, it has an adverse impact on interconnects by degrading its electrical performance and reliability. Scaling causes reduction in interconnect linewidth, which leads to surge in resistance due to increased contributions from grain boundary and surface scattering of electrons in the metal lines. Further, current density inside interconnects is also enhanced by the reduced linewidth and is approaching or exceeding the current-carrying capacity of the existing interconnect metals, copper (Cu) and tungsten (W). The resulting failure due to electromigration presents a critical challenge for end-of-roadmap IC technology nodes. Therefore, alternative materials such as nanocarbons and silicides are being investigated as potential replacements for Cu and W as they have superior electrical and mechanical properties in the nanoscale. In this review, the electrical properties of nanocarbons, in particular carbon nanotubes (CNTs), are examined and their performance and reliability in the sub-100 nm regime are assessed. Further, the measured properties are used to project 30 nm CNT via properties, which are compared with those of Cu and W. | A unique approach using the large photoacoustic effect of single-walled carbon nanotubes (SWNTs) for targeting and selective destruction of cancer cells is demonstrated. SWNTs exhibit a large photoacoustic effect in suspension under the irradiation of a 1064-nm Q-switched millisecond pulsed laser and trigger a firecracker-like explosion at the nanoscale. By using such an explosion, a photoacoustic agent is developed by functionalizing the SWNTs with folate acid (FA) that can selectively bind to cancer cells overexpressing folate receptor on the surface of the cell membrane and kill them through SWNT explosion inside the cells under the excitation of millisecond pulsed laser. The uptake pathway of folate-conjugated SWNTs into cancer cells is investigated via fluorescence imaging and it is found that the FA-SWNTs can enter into cancer cells selectively with a high targeting capability of 17-28. Under the treatment of 1064-nm millisecond pulsed laser, 85% of cancer cells with SWNT uptake die within 20 s, while 90% of the normal cells remain alive due to the lack of SWNTs inside cells. Temperature changes during laser treatment are monitored and no temperature increases of more than +/- 3 degrees C are observed. With this approach, the laser power used for cancer killing is reduced 150-1500 times and the therapy efficiency is improved. The death mechanism of cancer cells caused by the photoacoustic explosion of SWNTs is also studied and discussed in detail. These discoveries provide a new way to use the photoacoustic properties of SWNTs for therapeutic applications. | eng_Latn | 11,616 |
After a period of considerable and sustained hegemony, many commentators have argued that contemporary processes of globalisation are acting as a challenge to nation state sovereignty. The paper argues that geographers need to focus on the ways in which the nation state continues to act, albeit in a modified manner, within the era of globalisation. This might help to position geography within globalisation debates, which––according to Dicken [Geographers and `globalization': (yet) another missed boat? forthcoming, Transactions of the Institute of British Geographers, 2004]––we have not been centrally involved in. Drawing on the work of Michael Mann, we focus on a neglected dimension of state power––namely, its ideological form––as a means of exploring how the nation state is being differentially re-engineered under globalisation. Using Mann's classification of forms of ideological organisation, we deploy three vignettes in order to demonstrate the evolving nature of ideological power within the contemporary UK State. | A century ago, the American Geographical Society (AGS), then a half-century old, helped give birth to the Association of American Geographers (AAG), succored the fledgling association, and long rendered it invaluable support. By the mid-twentieth century, the shoe was on the other foot: a mature and much larger AAG was being urged to lend help to the AGS. This article details their intertwined histories and personnel and reflects on their differing takes on geography as a specialized academic discipline and as a comprehensive amateur enterprise. *An earlier draft of this article was prepared for a panel discussion at the AAG centennial annual meeting in Philadelphia in March 2004. My thanks to Mary Lynne Bird for generating it and to David Hooson for delivering it. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,617 |
The article examines the American political efforts to bring about an agreement between Israel and Egypt between 1967 and 1969 and analyses the reasons for their failure. But it does not focus exclusively on the Americans; it also outlines the alternatives for Egyptian action during the period in question and looks at the political and military steps taken by Egypt's president, Gamal Abdel Nasser, vis-a-vis Israel and the United States. The main conclusion is that despite Egypt's dependence on the Soviet Union for economic aid and the rebuilding of the decimated Egyptian army, Nasser knew that the only route to a political process to regain Sinai ran through the United States. His diplomatic efforts were all derived from this insight. At the same time, the Egyptian president's attempts to exploit American pressure to his benefit, as he had done in 1957, was undercut by his overestimation of his bargaining chips, a mistake that was one factor in the collapse of the efforts to reach a diplomatic agreement i... | The Nation of Islam’s influence has extended beyond the United States. This Black American Muslim movement has used the intersection of race and religion to construct a blueprint of liberation that has bonded people of African descent throughout the Diaspora. Their transnational dimensions and ideas of freedom, justice and equality have worked to challenge global white imperialism and white supremacy throughout the 20th century and beyond. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,618 |
Used as a bare active material or component in hybrids, graphene has been the subject of numerous studies in recent years. Indeed, from the first report that appeared in late July 2008, almost 1600 papers were published as of the end 2015 that investigated the properties of graphene as an anode material for lithium-ion batteries. Although an impressive amount of data has been collected, a real advance in the field still seems to be missing. In this framework, attention is focused on the most prominent research efforts in this field with the aim of identifying the causes of such relentless progression through an insightful and critical evaluation of the lithium-ion storage performances (i.e., 1st cycle irreversible capacity, specific gravimetric and volumetric capacities, average delithiation voltage profile, rate capability and stability upon cycling). The “graphene fever” has certainly provided a number of fundamental studies unveiling the electrochemical properties of this “wonder” material. However, analysis of the published literature also highlights a loss of focus from the final application. Hype-driven claims, not fully appropriate metrics, and negligence of key parameters are probably some of the factors still hindering the application of graphene in commercial batteries. | Carbon nanosheets were successfully prepared from easily available and low-cost petroleum asphalt via a facile and recyclable molten-salt method. The as-made carbon nanosheets exhibit excellent performance on energy storage both for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs): as the anode of LIBs, they provide a high reversible specific capacity (729 mAh g −1 at 100 mA g −1 ), excellent cyclability (600 mAh g −1 at 1 A g −1 after 500 cycles), and improved rate performance (280 mAh g −1 at 5 A g −1 ). For SIBs, they also display a reversible capacity of 300 mAh g −1 at 50 mA g −1 , remarkable rate capability (90 mAh g −1 at 5 A g −1 ) and retain as high as 95 mAh g −1 after 10000 cycles at 2 A g −1 . The superior electrochemical performance of carbon nanosheets could be attributed to their peculiar structural characteristics that integrate a variety of advantages: fast electronic and ionic conductivity, easy penetration of the electrolyte, shortened path for Li + /Na + migration and structural stability. This approach paves the way for industrial scale-up due to its eco-friendliness, simplicity and versatility. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,619 |
The photopolymer material of poly(vinyl cinnamate) (PVCi) is known as a liquid-crystal (LC) alignment film whose surface azimuthal anchoring energy is relatively small. However, the results of an experiment on LC reorientation under an electric field suggest that the genuine azimuthal anchoring energy is one order of magnitude higher than that measured by the conventional torque balance method and/or the N?el wall method. Here we clarified that this inconsistency is due to the LC molecular adsorption on the alignment film occurring during the isotropic-nematic phase transition process. In this paper, we propose an improved torque balance method by which the genuine azimuthal anchoring energy can be estimated. | A series of experiments [C. Poulard and A. M. Cazabat, “Spontaneous spreading of nematic liquid crystals,” Langmuir 21, 6270 (2005)] on spreading droplets of nematic liquid crystal (NLC) reveals a surprisingly rich variety of behaviors. Small droplets can either be arrested in their spreading, spread stably, destabilize without spreading (corrugated surface), or spread with a fingering instability and corrugated free surface. In this work, we discuss the problem of NLC drops spreading in a simplified two-dimensional (2D) geometry. The model that we present is based on a long-wavelength approach for NLCs by Ben Amar and Cummings [“Fingering instabilities in driven thin nematic films,” Phys. Fluids 13, 1160 (2001); L. J. Cummings, “Evolution of a thin film of nematic liquid crystal with anisotropic surface energy,” Eur. J. Appl. Math. 15, 651 (2004)]. The improvements in the model here permit fully nonlinear time-dependent simulations. These simulations, for the appropriate choice of parameter values, exhib... | It is desirable to develop an energy storage system with both high energy density and high power density along with excellent cycling stability to meet practical application requirements. Lithium-ion capacitors (LICs) are very promising due to the combined merits of the high power density of electrochemical capacitors and the high energy density of batteries. However, the lack of high rate performance anode materials has been the major challenge of lithium-ion capacitors. Herein, we designed and synthesized holey graphene-wrapped porous TiNb24O62 as an anode material for lithium-ion capacitors. Pseudocapacitive storage behaviors with fast kinetics, high reversibility, and excellent cycling stability were demonstrated. The hybrid material can deliver a high capacity of 323 mAh g−1 at 0.1 A g−1, retaining 183 mAh g−1 at 10 A g−1. Coupled with a carbon nanosheet-based cathode, an LIC with an ultrahigh energy density of 103.9 Wh kg−1 was obtained, and it retained 28.9 Wh kg−1 even under a high power density of 17.9 kW kg−1 with a high capacity retention of 81.8% after 10,000 cycles. A holey graphene-wrapped porous TiNb24O62 microparticles for ultrafast pseudocapacitive lithium storage is studied. Due to the nanoscale dimensions and hierarchically porous channels of the nanocomposite material, the hybrid material exhibits both excellent rate performance and stability. Coupling with carbon nanosheet cathode, the fabricated lithium-ion capacitor demonstrate high energy and power density as well as utralong cycling stability. | eng_Latn | 11,620 |
A detailed description of plasma–solid interaction is desirable for many technological applications such as plasma surface treatment and also for the development of plasma diagnostic techniques. To solve this rather complex problem, especially in the case of highly collisional or chemically active plasmas, methods of computational physics have to be used. In this paper, we present results of two-dimensional simulations based on the combination of molecular dynamics with particle-in-cell force calculation and the Monte Carlo method. An electropositive argon plasma with parameters taken from a DC glow discharge and an idealized Ar/O 2 plasma were studied for uneven substrates in order to determine the behaviour of plasmas with different electronegativities. | The results of 2D particle and 3D particle/uid hybrid simulations are presented. We investigated a plasma sheath formed near substrates of dierent shapes and showed the inuence of magnetic eld on the sheath structure and particle uxes to the substrate. The studied solids were a cylindrical and a planar probe and a grooved planar substrate. The object of interest was idealized three- component plasma containing electrons and one species of positive and negative ions. This composition simulates frequently used plasma mixtures containing electronegative gas (e.g. oxygen or chlorine) and rare gas (e.g. argon). We used a simplied plasma composition to show general properties of electronegative plasmas interacting with solids. The eects of the presence of negative ions were investigated together with the eects of magnetic eld. The simulations of plasma-solid interaction are useful not only for many plasma material treatment applications but also for an analysis of plasma probe diagnostics. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,621 |
Velocity diffusion has been observed to be significantly above that given by quasilinear theory in both test‐particle and self‐consistent simulations of the dynamics of turbulent electrostatic fields. Test‐particle simulations and analytic calculations for motion in a set of randomly phased waves find the diffusion coefficient to be enhanced by a factor of 2.5 at intermediate values of the overlap parameter. Self‐consistent simulations find that the turbulent spectrum can evolve naturally into a form such that the diffusion enhancement is present when the linear growth time of the modes is long compared with the effective discretization time, which is nearly an order of magnitude greater than the resonant broadening time. | A system of N particles \(\xi ^N = x_1 ,\upsilon_1,...,x_N ,\upsilon _N )\) interacting self-consistently with one wave Z = A exp(iφ) is considered. Given initial data (Z(N)(0), ξ N (0)), it evolves according to Hamiltonian dynamics to (Z(N)(t), ξ N (t)). In the limit N → ∞, this generates a Vlasov-like kinetic equation for the distribution function f(x, v, t), abbreviated as f(t), coupled to the envelope equation for Z: initial data (Z(∞)(0), f(0)) evolve to (Z(∞)(t), f(t)). The solution (Z, f) exists and is unique for any initial data with finite energy. Moreover, for any time T>0, given a sequence of initial data with N particles distributed so that the particle distribution fN(0) → f(0) weakly and with Z(N)(0) → Z(0) as N → ∞, the states generated by the Hamiltonian dynamics at all times 0 ≤ t ≤ T are such that (Z(N)(t), fN(t)) converges weakly to (Z(∞)(t), f(t)). | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,622 |
The investigation of energy transfer properties in photosynthetic multi-protein networks gives insight into their underlying design principles.Here, we discuss excitonic energy transfer mechanisms of the photosystem II (PS-II) C$_2$S$_2$M$_2$ supercomplex, which is the largest isolated functional unit of the photosynthetic apparatus of higher plants.Despite the lack of a decisive energy gradient in C$_2$S$_2$M$_2$, we show that the energy transfer is directed by relaxation to low energy states. C$_2$S$_2$M$_2$ is not organized to form pathways with strict energetic downhill transfer, which has direct consequences on the transfer efficiency, transfer pathways and transfer limiting steps. The exciton dynamics is sensitive to small structural changes, which, for instance, are induced by the reorganization of vibrational coordinates. In order to incorporate the reorganization process in our numerical simulations, we go beyond rate equations and use the hierarchically coupled equation of motion approach (HEOM). While transfer from the peripherical antenna to the proteins in proximity to the reaction center occurs on a faster time scale, the final step of the energy transfer to the RC core is rather slow, and thus the limiting step in the transfer chain. Our findings suggest that the structure of the PS-II supercomplex guarantees photoprotection rather than optimized efficiency. | Electronic and Vibrational Molecular States. Dynamics of Isolated and Open Quantum Systems. Vibrational Energy Relaxation and Redistribution. Intramolecular Electronic Transitions. Electron Transfer. Proton Transfer. Exciton Transfer. Concluding Remarks. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,623 |
Finite-element modeling for efficient organic bulk-heterojunction photovoltaics is presented. Given the complexity of the architecture, it has been hard to devise a sufficiently compact description of the physics of charge and exciton dynamics. This paper delineates the most essential set of equations that allow to reproduce the major characteristics of a current---voltage curve measured under illumination. Parameters are extracted by optimization of a fabricated polymer/fullerene cell, and by deliberately changing key parameters, further understanding is established on the phenomenological manifestation of independent physical processes. | Nanostructured and chemically modified graphene-based nanomaterials possess intriguing properties for their incorporation as an active component in a wide spectrum of optoelectronic architectures. From a technological point of view, this aspect brings many new opportunities to the now well-known atomically thin carbon sheet, multiplying its application areas beyond transparent electrodes. This article gives an overview of fundamental concepts, theoretical backgrounds, design principles, technological implications, and recent advances in semiconductor devices that integrate nanostructured graphene materials into their active region. Starting from the unique electronic nature of graphene, a physical understanding of finite-size effects, non-idealities, and functionalizing mechanisms is established. This is followed by the conceptualization of hybridized films, addressing how the insertion of graphene can modulate or improve material properties. Importantly, it provides general guidelines for designing new materials and devices with specific characteristics. Next, a number of notable devices found in the literature are highlighted. It provides practical information on material preparation, device fabrication, and optimization for high-performance optoelectronics with a graphene hybrid channel. Finally, concluding remarks are made with the summary of the current status, scientific issues, and meaningful approaches to realizing next-generation technologies. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,624 |
Organizations store their information in electronic or paper documents. This information is severely underutilized in the daily work of most organizations. Because there are no effective means to access the documents, employees do not find relevant information, or are not even aware of its existence. We describe Information Tuning - a first step towards knowledge management in enterprises. Information Tuning capitalizes on existing documents and enables better exploitation of the contained knowledge by adding the background, context, and meta information which is necessary for making possible beneficial utilization, sharing, and reuse. We present an Information Tuning method which evolved from model-based knowledge acquisition from texts, and illustrate the method with application examples. Information Tuning is supported by the KARAT tool which applies techniques from text analysis and hypertext technology. | In recent years, we have been developing a new framework for acquiring medical knowledge from Encyclopedic texts. This framework consists of three major parts. The first part is an extended high-level conceptual language (called HLCL 1.1) for use by knowledge engineers to formalize knowledge texts in an encyclopedia. The other part is an HLCL 1.1 compiler for parsing and analyzing the formalized texts into knowledge models. The third part is a set of domain-specific ontologies for sharing knowledge. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,625 |
The capture/push behavior of a particle in front of a solidification interface was analyzed theoretically and experimentally in this work. Van der Waals force, viscous force, and force due to interfacial energy played important roles in the particle capture/push process. Directional solidification experiments were conducted with nano-sized SiC particle-reinforced AZ91D composites to observe the distribution of nanoparticles in different solidification morphologies under varied cooling rates. When the composite solidified with plane manner, the nanoparticles could be captured by the solidification front and distributed uniformly in the matrix. When solidified with columnar or equiaxial manners, the nanoparticles could be captured by the solidification front but distributed uniformly only in the grain boundary as a result of the difference in interfacial energy and wettability between SiC/α-Mg and SiC/eutectic phase. Theoretical prediction of particle capture was in agreement with the experiment results. | In this article, a new mechanism so-called wet cluster engulfment and the related formula were proposed to predict the critical solidification velocity for nanoparticles engulfment by a solidification front. According to the mechanism, the most important issue in the engulfing of the nanoparticles is the aggregation of nanoparticles, i.e. the formation of wet clusters in front of solidifying phase. In fact, local clustering of nanoparticles created highly viscous zones in the vicinity of the solidification front so that the nanoparticles and the liquid-filled spaces between them move as a unified mass. Thus, the van der Waals and drag forces between a nanoparticles cluster and the solidification front were calculated analytically. The new formulae were derived for the critical solidification velocity and critical diameter of the clusters as a function of the melt viscosity, the nanoparticle size, the cluster size, and the nanoparticle volume concentration inside the cluster. The theoretical results showed... | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,626 |
Manipulating the morphology of inorganic nanostructures, such as their chirality and branching structure, has been actively pursued as a means of controlling their electrical, optical and mechanical properties. Notable examples of chiral inorganic nanostructures include carbon nanotubes, gold multishell nanowires, mesoporous nanowires and helical nanowires. Branched nanostructures have also been studied and been shown to have interesting properties for energy harvesting and nanoelectronics. Combining both chiral and branching motifs into nanostructures might provide new materials properties. Here we show a chiral branched PbSe nanowire structure, which is formed by a vapour-liquid-solid branching from a central nanowire with an axial screw dislocation. The chirality is caused by the elastic strain of the axial screw dislocation, which produces a corresponding Eshelby Twist in the nanowires. In addition to opening up new opportunities for tailoring the properties of nanomaterials, these chiral branched nanowires also provide a direct visualization of the Eshelby Twist. | The following article is an edited transcript based on the MRS Medalist presentation given by Charles M. Lieber of Harvard University on December 4, 2002, at the Materials Research Society Fall Meeting in Boston. Lieber received the Medal "for controlled synthesis of nanowire and nanotube materials." This presentation begins with an introduction to the bottom-up paradigm of nanoscience and nanotechnology. The key concepts of this paradigm are explored through studies outlining progress toward meeting the challenge of nanocomputing through the assembly of functional nanowire elements. The richness of the bottom-up paradigm and nanowire building blocks is then illustrated with the development of chemical and biological nanosensors. Finally, the uniqueness of nanowires is exemplified through discussion of the assembly of nanophotonic devices, including the demonstration of multicolor and addressable nanoscale light-emitting diodes, nanowire injection lasers, and assembled arrays of these nanophotonic sources. Challenges and goals for realizing nanotechnologies in the future are discussed in the conclusion. | Blunt trauma abdomen rarely leads to gastrointestinal injury in children and isolated gastric rupture is even rarer presentation. We are reporting a case of isolated gastric rupture after fall from height in a three year old male child. | eng_Latn | 11,627 |
A concept of two steps voltage increasing mode derived from constant voltage mode was developed to fabricate micro-arc oxidation (MAO) coatings on ZK60 Mg alloy. Growth characteristic, microstructure and corrosion resistance of coatings were investigated and compared with the constant voltage mode. An additional and distinguishing stage is found and regarded as a coating regrowth stage playing an important role on coating thickness. Effects of increase value of voltage were also investigated. It shows that rougher and thicker coating is formed for higher value of voltage. And it is more likely to induce destructive arc discharge for excessive increase value, thus leads to a looser and less corrosion resistant coating. The coating formed under two steps voltage-increasing mode of 280-360V exhibits the best corrosion resistance. | The effects of different negative voltages on micro-arc oxidation coating fabricated on ZK60 Mg alloy were investigated under two steps increasing mode of 280-360V. The microstructure, coating thickness and corrosion resistance of coatings were evaluated by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), microscope with super-depth of field and electrochemical impedance spectroscopy (EIS). Current-time responses during MAO process were also analyzed combined with coating characteristic. The results reveal that higher negative voltage helped to develop a compact, smooth, thicker and better corrosion-resistant coating. The coating with maximum thickness of about 20.2μm formed under negative voltage of 20V exhibits higher impedance value and the best corrosion resistance. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,628 |
Nanomaterials offer large reaction surfaces making for high-rate lithium-ion transfer and fewer constraints to avoid fracture. Nevertheless, surface effect arises inevitably due to so high surface-to-volume ratio. Accordingly, the fundamental framework of surface stress is involved to study diffusion-induced stresses within electrode nanoparticles in this work. As simple one-dimension models, solid and hollow nanowire electrode particles are investigated. The results show that surface tensile stress produces compressive stresses through the electrode materials, especially reducing maximum tensile stress, which may become a resistance to brittle fracture. Owing to high special surface area, it is demonstrated that diffusion-induced stresses for hollow materials are largely reduced compared to solid electrode materials. The influences of surface modulus on diffusion-induced stresses are much stronger under generalized plane strain condition in comparison with plane strain condition. Analysis based on the Tr... | This paper presents a comprehensive model coupling the effects of hydrostatic stress, surface/interface stress, phase transformation and the structure of electrodes. First, the governing equation o... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,629 |
Hexagonal boron nitride ( h BN) monolayers have attracted considerable interest as atomically thin sp 2 -hybridized sheets that are readily synthesized on various metal supports. They complement the library of two-dimensional materials including graphene and open perspectives for van der Waals heterostructures. In this review, we discuss the surface science of h BN including its growth, the h BN/metal interface and its application as template for adsorbates. We mainly focus on experimental studies on h BN/metal single crystals under ultra-high vacuum conditions. The interfaces are classified regarding their geometric structure - ranging from planar to strongly corrugated overlayers - and their electronic properties - covering weakly and strongly interacting systems. The main part of this review deals with h BN/metal substrates acting as supports for adsorbates such as individual atoms, metal clusters, organic molecules, metal-organic complexes and networks. We summarize recent surface science studies that reveal the unique role of the h BN/metal interfaces in tailoring characteristic properties of such adsorbates. Central aspects include templating and self-assembly, catalytic activity and on-surface reactions, electronic and magnetic structure. As many of the resulting systems feature superstructures with periodicities in the nanometer range, a length scale also reflecting the size of adsorbates, scanning probe microscopy is one of the most common techniques employed. In short, the goal of this review is to give an overview on the experimental and complementary theoretical studies on h BN templates available to date and to highlight future perspectives. | Near-ambient pressure X-ray photoelectron spectroscopy and scanning tunneling microscopy experiments are performed to study the intercalation of oxygen and nitrogen at different partial gas pressures and different temperatures in the graphene/Ni/Ir(111) system of different morphologies. We performed detailed experiments to investigate the chemical state and topography of graphene, before and after gas intercalation, depending on the amount of pre-intercalated Ni in graphene/Ir(111). It is found that only oxygen can be intercalated under graphene in all considered cases, indicating the role of the intramolecular bonding strength and possibility of gas molecules dissociation on different metallic surfaces on the principal possibility and on the mechanism of intercalation of different species under graphene. | Blunt trauma abdomen rarely leads to gastrointestinal injury in children and isolated gastric rupture is even rarer presentation. We are reporting a case of isolated gastric rupture after fall from height in a three year old male child. | eng_Latn | 11,630 |
Molecular-dynamics simulations were used to investigate the storage capacity of hydrogen in single-walled carbon nanotubes (SWNT's) and the strain of nanotube under the interactions between the stored hydrogen molecules and the SWNT. The storage capacities inside SWNT's increase with the increase of tube diameters. For a SWNT with diameter less than 20 A, the storage capacity depends strongly on the helicity of a the SWNT. The maximal radial strain of SWNT is in the range of 11%-18%, and depends on the helicity of the SWNT. The maximal strain of armchair SWNT's is less than that of zigzag SWNT's. The tensile strengths of SWNT's decrease with increasing diameters, and approach that of graphite (20 GPa) for larger-diameter tubes. | Theoretical (thermodynamic) and experimental backgrounds are considered for developing a much simpler, more technological and effective method (in comparison with the known megabar compression dynamic and static meth- ods) of producing a high-density solid molecular ("reversible") hydrogen carrier by means of hydrogen intercalation (at the cost of the hydrogen association energy) in carbonaceous nanomaterials (between graphane-like layers) at relevant temperatures and pressures. As is shown, one of the processes of chemisorption of hydrogen in carbonaceous nanomateri- als may be related to formation of graphane-like (carbohydride-like) complexes and/or multilayer graphane-like nanos- tructures. In this connection, some aspects of the graphene/graphane problem are considered, as well. By using gravimet- ric and electron microscopy data, the density values (� H = 0.7±0.2 g(H2)/�� 3 (H2), and � *H = 0.28±0.08 g(H2)/�� 3 (system) - the "volumetric" capacity) of the intercalated solid molecular ("reversible") hydrogen (of a high purity) in graphane-like nanofibers ( 15 mass % H2 - the "gravimetric" capacity) have been defined. It is a much more acceptable, safe and effi- cient technology, in comparison with the current technologies of composite vessels with high hydrogen pressure (about 80 MPa) and the current space cryogenic technologies of hydrogen on-board storage in fuel-cell-powered vehicles. It exceeds and/or corresponds to the known U.S. DOE requirements-targets for 2015, with respect to the hydrogen capacities, safety, reversibility and puirity. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,631 |
There is the need for a clear understanding of the transition process and economic development in Ethiopia. The country’s move towards a free market economy will be critically analyzed as an important step to fight poverty. This will also raise the question of what policies need to be changed to make the nation competitive, or what are the steps to be taken to have a successful transition to market driven economy? A case method is taken into consideration to examine various experiences from African and Asian developing nations. The content is examined from leadership perspective and primarily utilizes free market transitional theories. The following factors are carefully examined in the study of transition to market economy: Porter’s Diamond; particularly national competitiveness, the need to promote higher education, and policy changes needed to accommodate this transition process. The transition is important step for the nation’s competitiveness and will impact poverty level. The policy change must be followed by institutional adaptation to support the reform process. It is also clear that success is correlated with leadership and advancing education. In addition, there is weak relation between democracy and success of the transition effort. | The failures of communism outline of a new society the capacity to change how great? relevant analogies in economic history sequencing - shock therapy versus gradualism internal liberalization opening the economy currency reform macroeconomic stabilization privatization. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,632 |
Methods of preparing silicon nitride and materials as powders, and as materials consolidated from the powders, and also as films and coatings, are reviewed. Information on the structure and on the physicochemical properties of silicon nitride materials is analysed and discussed. The bibliography includes 172 references. | A ceramic with dense nanosize structure was obtained by conventional sintering of samples formed from nanosize Si3N4 powder with Al2O3 and Y2O3 additives by cold isostatic pressing. The microstructure and density of the ceramic obtained were investigated. The technological conditions for obtaining silicon nitride ceramic that give the optimal combination of fine-grain submicron structure and high density were determined. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,633 |
Our analysis of the experimental data related to nonphotochemical laser induced nucleation in solutions leads to the inevitable conclusion that the phase transformation is initiated by particles that are metallic in nature. This conclusion appears paradoxical because the final products are dielectric crystals. We show that the experimental results are well accounted for by the theory of electric field induced nucleation of metallic particles that are elongated in the direction of the field. However, new physical and chemical insights are required to understand the structure of the metallic precursor particles and the kinetics of subsequent dielectric crystallization. | We consider the effect of metal electrodes on the polarizability and nucleation of metal phases responsible for the operations of the emerging solid state memory. Our analysis is based on the image charge approach. We find results for point dipoles in static and oscillatory fields as well as an erect cylindrical nucleus near metal surfaces in resistive switching memories. We predict a large increase in polarizability and nucleation rate due to the metal electrode effects. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,634 |
Subwavelength diameter microfiber with carbon nanotube (CNT) cladding attracts wide attention for its significant effect on evanescent coupling and interaction. In this paper, the physical mechanism and spatial expression of the light field near CNT coated microfiber are analyzed by the electromagnetic calculation and mode field analysis experiments. The simulated and experimental results demonstrate that light field distribution along the CNT coated microfiber shows the resonant modes with intensity attenuation locating at ∼0 μm, 1.7 μm, 3.3 μm at the direction of core radius. The investigation about interaction between evanescent wave and CNT films will inspire the future application of CNT films and microfiber based lasers, all-optical switches, wavelength converters, sensors, and other integrated functional photonic devices. | Graphene has been attracting great interest as the basis of novel photonic devices and sensors due to its many unique optical and electric properties that are quite different from conventional film materials. In this paper, we propose and demonstrate a novel hybrid graphene-microfiber waveguide structure and its application to chemical gas sensing for the first time to our knowledge. As the complex refractive index of the extremely thin graphene film (<;1 nm) can be easily modified by chemical gas molecules distributing on its surface, the transverse electric mode surface wave intensity is sensitive to gas concentration. Such an intensity modulation induced by gas molecules can be detected via the coupling of evanescent field between the graphene waveguide and the microfiber. A sensitivity of 0.31 dB/100 ppm and good reversibility are observed experimentally for acetone vapor gas sensing. It is believed that this hybrid waveguide structure could open a new window to realize a variety of graphene-based photonic sensors, for potential applications in the fields of biology, medicine, and chemistry. | Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) are potential materials for the most advanced silicon devices and circuits due to their excellent electrical properties such as high current capacity and tolerance to electromigration. In addition, at high frequencies, these materials exhibit transport behavior which holds promise for applications as on-chip interconnects. | eng_Latn | 11,635 |
The authors report on a new tungsten-hardmask-based diamond dry-etch process for fabricating diamond zone plate lenses with a high aspect ratio. The tungsten hardmask is structured by electron-beam lithography, together with Cl2/O2 and SF6/O2 reactive ion etching in a trilayer resist-chromium-tungsten stack. The underlying diamond is then etched in an O2 plasma. The authors demonstrate excellent-quality diamond gratings with half-pitch down to 80 nm and a height of 2.6 μm, as well as zone plates with a 75 μm diameter and 100 nm outermost zone width. The diffraction efficiency of the zone plates is measured to 14.5% at an 8 keV x-ray energy, and the imaging properties were investigated in a scanning microscope arrangement showing sub-100-nm resolution. The imaging and thermal properties of these lenses make them suitable for use with high-brightness x-ray free-electron laser sources. | Focusing hard x-ray free-electron laser radiation with extremely high fluence sets stringent demands on the x-ray optics. Any material placed in an intense x-ray beam is at risk of being damaged. Therefore, it is crucial to find the damage thresholds for focusing optics. In this paper we report experimental results of exposing tungsten and diamond diffractive optics to a prefocused 8.2 keV free-electron laser beam in order to find damage threshold fluence levels. Tungsten nanostructures were damaged at fluence levels above 500 mJ/cm(2). The damage was of mechanical character, caused by thermal stress variations. Diamond nanostructures were affected at a fluence of 59 000 mJ/cm(2). For fluence levels above this, a significant graphitization process was initiated. Scanning Electron Microscopy (SEM) and µ-Raman analysis were used to analyze exposed nanostructures. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,636 |
Graphene provides a fascinating testbed for new physics and exciting opportunities for future applications based on quantum phenomena. To understand the coherent flow of electrons through a graphene device, we employ a nanoscale probe that can access the relevant length scales--the tip of a liquid-He-cooled scanning probe microscope (SPM) capacitively couples to the graphene device below, creating a movable scatterer for electron waves. At sufficiently low temperatures and small size scales, the diffusive transport of electrons through graphene becomes coherent, leading to universal conductance fluctuations (UCF). By scanning the tip over a device, we map these conductance fluctuations versus scatterer position. We find that the conductance is highly sensitive to the tip position, producing delta G approximately e(2)/h fluctuations when the tip is displaced by a distance comparable to half the Fermi wavelength. These measurements are in good agreement with detailed quantum simulations of the imaging experiment and demonstrate the value of a cooled SPM for probing coherent transport in graphene. | The temperature effect of quantum interference on resistivity is examined in monolayer graphene, with experimental results showing that the amplitude of the conductance fluctuation increases as temperature decreases. We find that this behavior can be attributed to the decrease in the inelastic scattering (dephasing) rate, which enhances the weak localization (WL) correction to resistivity. Following a previous report that explained the relationship between the universal conductance fluctuation (UCF) and WL regarding the gate voltage dependence (Terasawa et al., 2017) [19], we propose that the temperature dependence of the UCF in monolayer graphene can be interpreted by the WL theory. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,637 |
We present a simple yet effective one-step approach with a specially designed substrate holder to synthesize single crystalline ternary CdSxSe1–x nanobelts with uniform chemical stoichiometry and accurately controllable compositions (0 ≤ x ≤ 1). The micromorphologies and detailed structures of these nanobelts were studied by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, micro-Raman spectra, and energy-dispersive X-ray spectroscopy. The elements distribution was explored using elemental mapping. All the characteristic results indicate that the nanobelts exhibit high quality single crystalline wurtzite structure. Photoluminescence spectra obtained from these nanobelts show that the near-band-edge energy can be systematically modulated in the range of 1.73 to 2.44 eV. Functional electrical application of these nanobelts was achieved by a fabricated CdSxSe1–x nanonet-field effect transistor (FET). A lower threshold voltage and a much higher ON–OFF ratio tha... | Arrays of ZnO/CdSSe core/shell nanowires with shells of tunable band gaps represent a class of interesting hybrid nanomaterials with unique optical and photoelectrical properties due to their type II heterojunctions and chemical compositions. In this work, we demonstrate that direct focused laser beam irradiation is able to achieve localized modification of the hybrid structure and chemical composition of the nanowire arrays. As a result, the photoresponsivity of the laser modified hybrid is improved by a factor of ~3. A 3D photodetector with improved performance is demonstrated using laser modified nanowire arrays overlaid with monolayer graphene as the top electrode. Finally, by controlling the power of the scanning focused laser beam, micropatterns with different fluorescence emissions are created on a substrate covered with nanowire arrays. Such a pattern is not apparent when imaged under normal optical microscopy but the pattern becomes readily revealed under fluorescence microscopy i.e. a form of Micro-Steganography is achieved. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,638 |
This paper presents a semi-analytical model (SAM) for three-dimensional frictional magnetoelectroelastic (MEE) contact of two multiferroic bodies, together with a set of effective solution methods. The frequency response functions (FRFs) for the MEE fields in a multiferroic half-space are analytically derived with respect to a unit concentrated normal force, a unit concentrated tangential force, a unit electric charge, and/or a unit magnetic charge, which are then converted into the results of continuous Fourier transforms of the influence coefficients (ICs), followed by the discrete Fourier transforms with a proper aliasing treatment. The conjugate gradient method (CGM) is used to obtain the unknown distributed pressure. Furthermore, the discrete convolution-fast Fourier transform (DC-FFT) algorithm is implemented to calculate the in-plane electric/magnetic potentials and subsurface stresses. The model is implemented to analyze the frictional sliding contact between a half-space and a sphere, and to study the coupled effects of surface electric/magnetic charges and friction on contact behaviors, including pressure, stresses, and electric/magnetic potentials. A sensitivity analysis is also conducted to evaluate the influences of friction and material properties on the contact-induced multifield coupling behaviors. A number of case studies are committed, and the results indicate that electric/magnetic charge densities and the friction coefficient strongly influence the contact pressure, stress, and electric potential. | Author(s): Zhang, Xin; Wang, Q Jane; Harrison, Katharine L; Jungjohann, Katherine; Boyce, Brad L; Roberts, Scott A; Attia, Peter M; Harris, Stephen J | © The Author(s) 2019. Published by ECS. We offer an explanation for how dendrite growth can be inhibited when Li metal pouch cells are subjected to external loads, even for cells using soft, thin separators. We develop a contact mechanics model for tracking Li surface and sub-surface stresses where electrodes have realistically (micron-scale) rough surfaces. Existing models examine a single, micron-scale Li metal protrusion under a fixed local current density that presses more or less conformally against a separator or stiff electrolyte. At the larger, sub-mm scales studied here, contact between the Li metal and the separator is heterogeneous and far from conformal for surfaces with realistic roughness: the load is carried at just the tallest asperities, where stresses reach tens of MPa, while most of the Li surface feels no force at all. Yet, dendrite growth is suppressed over the entire Li surface. To explain this dendrite suppression, our electrochemical/mechanics model suggests that Li avoids plating at the tips of growing Li dendrites if there is sufficient local stress; that local contact stresses there may be high enough to close separator pores so that incremental Li+ ions plate elsewhere; and that creep ensures that Li protrusions are gradually flattened. These mechanisms cannot be captured by single-dendrite-scale analyses. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,639 |
The resulting stationary states and scattering properties of an effective potential brought about by embedding a quantum well in another well are investigated in this work. The composite well system is constructed via a superposition of modified Poeschl - Teller potential wells. The energy spectrum in each composite well is obtained using the shooting method and the transport of a particle above this system is analyzed using the transfer matrix method. It is shown that decreasing the size of the embedded middle well lowers the ground state energy of the well-in-a-well system. Moreover, the bound states increase in number and become more evenly spaced. In addition, the transmission probability of a free particle incident above a composite well is lowest for the system with a large embedded well as compared to well-in-a-well systems of the same depth. Small variations in designed potential wells yield different quantum mechanical features. | Part I: One-Body Problems without Spin. One-Dimensional Problems. Problems of Two or Three Degrees of Freedom without Spherical Symmetry. The Angular Momentum. Potentials of Spherical Symmetry. The Wentzel-Kramers Brillouin (WKB) Approximation. The Magnetic Field.- Part II: Particles with Spin. One-Body Problems. Two-and Three-Body Problems. Many-Body Problems. Few Particles. Very Many Particles: Quantum Statistics. Non-Stationary Problems. The Relativistic Dirac Equation. Radiation Theory. Mathematical Appendix. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,640 |
Progress in electrorheology was reviewed for micro- and nano-suspensions. Characteristics required for the suspensions and related materials were shown. Some proposed models were discussed. Electrically induced microstructures, yielding, and related physical properties were also discussed in terms of theory and experiment. | Electro-rheological (ER) nano-suspensions based on titanium dioxide nano-particles with particle diameter around 400 nm and a chemically modified silicone oil with a viscosity of 0.04 Pa·s were prepared. Microgap flow behavior in the absence of an external electric field and the ER responses were investigated in relation to the microstructure observed in the quiescent state. The effects of the continuous phase of suspending oil and particle volume fraction were reported for the nano-suspensions. For the modified silicone oil-based nano-suspensions of 8.8 and 12 vol %, no plateau stresses were observed, whereas a plateau stress around 5 Pa was found only for the nano-suspension of 20 vol %. On the other hand, the ER effect of the modified silicone oil-based nano-suspension of 20 vol % was comparable to that of the silicone oil-based nano-suspension of 12 vol %. Simultaneous optical observations with the ER effect were also performed for the nano-suspension of 20 vol %. The effects of shear rate and time on the shear stress and flow behavior in the presence (or absence) of the dc electric field were reported, showing unexpected reduction of the ER effect and the shear thinning-like behavior with flow instability at higher shear rates. Possible factors for improving the ER effect were discussed in the present paper. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,641 |
The interfacial thermal resistance (ITR) between a carbon nanotube (CNT) and adjoining carbon, silicon, or copper substrate is investigated through non-equilibrium molecular dynamics simulation (NEMD). The theoretical phonon transmission also is calculated using a simplified form of the diffuse mismatch model (DMM) with direct simulation of the phonon density of states (DOS) under quasi-harmonic approximation. The results of theory and simulation are reported as a function of temperature in order to estimate the importance of anharmonicity and inelastic scattering. At 300K, the thermal conductance of CNT-substrate interfaces is ∼1500 W/mm2 K for diamond carbon, ∼500 W/mm2 K for silicon, and ∼250 W/mm2 K for copper.Copyright © 2009 by ASME | The miniaturization in energy devices and their critical needs for heat dissipation have facilitated research on exceptional thermal properties of novel low-dimensional materials. Current studies demonstrated the main challenge for solving thermal transport issues is the large thermal contact resistance across these low-dimensional material interfaces when they are either bundled together or supported by a substrate. A clear understanding of thermal transport across these atomic interfaces through experimental characterization or numerical simulation is important, but nontrivial. Due to instrumentation limit, only a few thermal characterization methods are applicable. Accordingly, many studies have been conducted by theoretical analysis and molecular dynamics to understand the physical process during this ultra-fast and ultra-small thermal transport. In this review, both experimental work and molecular dynamics studies on atomic-scale thermal contact resistance of low-dimensional materials (from zero- to two-dimensional) are reviewed. Challenges as well as opportunities in the study of thermal transport in atomic-layer structures are outlined. Considering the remarkable complexity of physical/chemical conditions, there is still a large room in understanding fundamentals of energy coupling across these atomic-layer interfaces. | Experimental and theoretical analyses were used to study the effect of thermal contact resistance in two materials, aluminum and graphite. Experimental investigation included the use of a modern laser flash device to measure the effective thermal conductivity of each material for three different cases: in direct contact, with a graphite coating and with a thin sheet of carbon nanotube (CNT) thermal interface material (TIM). For both materials total thermal resistance values were determined corresponding to different cases for same contact pressure. Results showed that the CNT TIM produced the minimum thermal contact resistance. A theoretical study was carried out to compare the experimental results with thermal resistance models from the literature. Based on the surface roughness of the materials tested, two models were used. Both models showed reasonable agreement with the experimental results with an error of less than 6.5 %. The results demonstrate the effectiveness of CNT materials in improving the thermal conductance of contacting surfaces. | eng_Latn | 11,642 |
We report on molecular dynamic calculations of combined tension–torsion of chiral single-wall nanotubes. We work within the framework of objective structures that exploits symmetry groups to enable torsion of chiral nanotubes, in addition to non-equilibrium extension. We apply the method to study the mechanical response and failure of nanotubes of various chiralities. We find that three distinct regimes exist for nanotubes under twist: distorted but unbuckled, reversible torsional buckling and irreversible torsional buckling. When twisted but unbuckled nanotubes are subject to tension, there is minimal change in failure strain, whereas reversibly buckled nanotubes have substantially reduced failure strain and load. We also observe the evolution of the twisting moment during the elongation process while keeping the twist angle fixed. This evolution has two interesting and potentially useful features: first, some nanotubes ‘unbuckle’ in the process of extension, and second, there is a clear correlation between extrema in the evolution of the twisting moment and impending nanotube failure. Given the sensitivity of electrical properties in carbon nanotubes to torsion, and the recent demonstrations of measuring torsion-induced changes, the latter feature suggests the possibility of real-time diagnostics to detect critical mechanical events. | While considerable efforts in the form of (numerical) atomistic simulations have been expended to understand the mechanics of defect formation under applied strain, analogous analytical efforts have been rather few. In this work, based on the physics at the nanoscale, defect nucleation in single-walled carbon nanotubes is studied using both classical continuum field theory as well as gauge field theory of defects. Despite the inherent continuum assumption in our models, reasonably close qualitative and quantitative agreement with existing atomistic simulations is obtained. The latter lends credence to the belief that continuum formulations, with correct incorporation of the relevant physics, can be a powerful and yet simple tool for exploring nanoscale phenomena in carbon nanotubes. The results are more sensitive to chirality than to the size of the nanotubes. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,643 |
An important and so far neglected class of structural elements affecting the overall properties of metal oxide nanopowders are interfaces between individual nanocrystals. In this work, we show experimentally that these defects inside a powder of compressed MgO nanocubes are subject to photoexcitation in the UV light range. In particular, we identify a so far unobserved photoluminescence emission process at 2.5 eV. First-principles calculations of the optical properties of nanocrystal interfaces provide plausible candidates for both light absorbing and emitting sites, which involve different types of interface features. It was found that edge dislocations that arise from interfaces between nanocube edges and terraces induce a significant electrostatic perturbation of the interfacial electronic states. This leads to exciton generation and luminescence at even lower energies than those related to corners and edges of MgO nanocubes. | The nature and magnitude of the optical gaps of rocksalt alkaline earth (MgO, CaO, SrO, MgS, MgSe) and transition metal chalcogenide (CdO, PbS) nanoparticles are studied using time-dependent density functional theory (TD-DFT) calculations on (MX)32 nanoparticles. We demonstrate, just as we previously showed for MgO, that TD-DFT calculations on rocksalt nanoparticles require the use of hybrid exchange-correlation (XC-)functionals with a high percentage of Hartree-Fock like exchange (e.g. BHLYP) or range-separated XC-functionals to circumvent problems related to the description of charge-transfer excitations. Concentrating on the results obtained with TD-BHLYP we show that the optical gap in rocksalt nanoparticles displays a wide range of behavior; ranging from large optical gaps stemming from a localized excitation involving corner atoms in alkaline earth oxides to a delocalized excitation and small optical gaps in the transition metal chalcogenides. Finally, we rationalize this wide range of behaviour in terms of differences in the degree to which the Coulombic interaction between the excited electron and hole is screened in the different nanoparticles, and relate it to the optical dielectric constants of the bulk materials the nanoparticles are made from. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,644 |
Rejecting simplifying notions of globalisation as a macro-economic force, this book provides a grounded picture of the various ways in which people's biographies are tied up with the global cultural economy. The main argument of the book is that the globalisation of lives is experienced by people as the 'extension' of their 'milieux' both spatially and symbolically. | In the context of globalization and European integration, the interplay between social boundaries and territorially defined political borders becomes more complex in that they become increasingly delinked. In some regional settings, this might imply that while the political border is softened, the socio-cultural closure between the border communities becomes even tighter. This article investigates this issue in relation to the German-Polish border region. Looking at the German-Polish twin-city, Guben-Gubin, the first section describes the ways in which cultural closure materializes. Emphasis is given to the link between cultural closure and an increasing alienation of local people from the Europeanized symbolic cross-border politics pursued by the local and regional political elite(s). The second section, however, argues that the "cultural closure" thesis is perhaps too simplistic to grasp the complexity of cross-border interaction of local people. Investigating the cross-border strategies of three milieux, the article concludes that what can be found in a setting like Guben-Gubin is in fact a complex configuration of openings and closures at various spatial and symbolic levels, sometimes taking place simultaneously in one and the same milieu. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,645 |
Grinding, as the last process of most products, directly affect the machining accuracy and surface quality of the product. Multi-parameter input and output and nonlinear mapping between the parameters of the grinding process play the most important part of computer simulation applied to grinding process. In this paper, the theory of computer simulation was introduced and a detail research on status of grinding process model and grinding process simulation system at foreign and domestic were elaborated, focused on the foreign academic research in this area. In the end, the paper presents an outlook of the research of grinding process simulation system. | Materials engineers easily recognize that the conduction of heat within solids is fundamental to understanding and controlling many processes. We could cite numerous examples to emphasize the importance of this topic. Some important applications that fall in this category include estimating heat losses from process equipment, quenching, or cooling operations where the cooling rate of a part actually controls its microstructure and hence its application, and solidification. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,646 |
We investigate one-dimensional aperiodic multilayer microstructures in order to achieve near-total absorptions at preselected wavelengths in a graphene monolayer. The proposed structures are designed using a genetic optimization algorithm coupled to a transfer matrix code. Coupled-mode-theory analysis, consistent with transfer matrix method results, indicates the existence of a critical coupling in the graphene monolayer for perfect absorptions. Our findings show that the near-total-absorption peaks are highly tunable and can be controlled simultaneously or independently in a wide range of wavelengths in the near-infrared and visible ranges. The proposed approach is metal-free, does not require surface texturing or patterning, and can be also applied for other two-dimensional materials. | Graphene has unique properties which make it an ideal material for photonic and optoelectronic devices. However, the low light absorption in monolayer graphene seriously limits its practical applications. In order to greatly enhance the light absorption of graphene, many graphene-based structures have been developed to achieve perfect absorption of incident waves. In this review, we discuss and analyze various types of graphene-based perfect absorption structures in the visible to terahertz band. In particular, we review recent advances and optoelectronic applications of such structures. Indeed, the graphene-based perfect absorption structures offer the promise of solving the key problem which limits the applications of graphene in practical optoelectronic devices. | 134. This article is concerned with the thermodynamic formulation of the Activated Complex Theory (otherwise called Transition State Theory or Absolute Rate Theory). ["Comments by the Editor" incorrectly cites Golden article as being from 1977. It's actually from 1971.] | eng_Latn | 11,647 |
Consumer electronics have increasingly relied on ultra-thin glass screen due to its transparency, scalability, and cost. In particular, display technology relies on integrating light-emitting diodes with display panel as a source for backlighting. In this study, we undertook the challenge of integrating light emitters onto amorphous quartz by demonstrating the direct growth and fabrication of a III-nitride nanowire-based light-emitting diode. The proof-of-concept device exhibits a low turn-on voltage of 2.6 V, on an amorphous quartz substrate. We achieved ~ 40% transparency across the visible wavelength while maintaining electrical conductivity by employing a TiN/Ti interlayer on quartz as a translucent conducting layer. The nanowire-on-quartz LED emits a broad linewidth spectrum of light centered at true yellow color (~ 590 nm), an important wavelength bridging the green-gap in solid-state lighting technology, with significantly less strain and dislocations compared to conventional planar quantum well nitride structures. Our endeavor highlighted the feasibility of fabricating III-nitride optoelectronic device on a scalable amorphous substrate through facile growth and fabrication steps. For practical demonstration, we demonstrated tunable correlated color temperature white light, leveraging on the broadly tunable nanowire spectral characteristics across red-amber-yellow color regime. | The catalyst-free molecular beam epitaxial growth of GaN nanowires and their heterostructures on a SiOx template is studied in detail. It was found that by optimizing the growth temperature, highly uniform and vertically aligned GaN nanowires and InGaN/GaN heterostructures with excellent optical properties can be obtained on a SiOx template in a large-scale. This work provides an entirely new avenue for GaN nanowire based optoelectronic devices. | Let E be an arbitrary directed graph and let K be any field. It is shown that the Leavitt path algebra A of the graph E over the field K is a Zorn ring if and only if the graph E satisfies the Condition (L), that is, every cycle in E has an exit. It is also shown that the Leavitt path algebra A is a weakly regular ring if and only if every homomorphic image of A is a Zorn ring. The corresponding statement for graph C*-algebras is also investigated. | eng_Latn | 11,648 |
We present an algorithm, instantiated in a freeware application called MeanTimes, that permits the parameterized production and transformation of a hierarchy of well-formed rhythms. Each "higher" rhythmic level fills in the gaps of all "lower" levels, and up to six such levels can be simultaneously sounded. MeanTimes has a slider enabling continuous variation of the ratios of the intervals between the beats onsets of the lowest level. This consequently changes-in a straightforward manner-the evenness of this level; it also changes-in a more complex, but still highly patterned manner-the evennesses of all higher levels. This specific parameter, and others used in MeanTimes, are novel: We describe their mathematical formulation, demonstrate their utility for generating rhythms, and show how they differ from those typically used for pitch-based scales. Some of the compositional possibilities continue the tradition of Cowell and Nancarrow, proceeding further into metahuman performance, and have perceptual and cognitive implications that deserve further attention. | In a comprehensive work with important implications for tuning theory and musicology, Easley Blackwood, a distinguished-composer, establishes a mathematical basis for the family of diatonic tunings generated by combinations of perfect fifths and octaves.Originally published in 1986.The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,649 |
This paper predicts the evolution of nanopores during anodic oxidation of aluminum. The theory is based on approximate nonlinear evolution equations of the interfaces, which reproduce all the observed patterns, and using them for stability analysis. The pore structure in the early stages is described by the Damped Kuramoto–Sivashinsky (DKS) equation, which predicts hexagonal patterns with points and line defects, in agreement with experimental observations of the evolving pores. This is the first work to follow pore dynamics. Comparison with asymptotic constant-thickness and -curvature solutions is conducted. | The self-organization of porous nanostructures in anodic metal oxide is consid- ered. A mathematical model which incorporates the chemical reactions at the metal-oxide and oxide-electrolyte interfaces and elastic stress caused by the electrostrictive efiects is de- veloped. It is shown through linear stability analysis, that a short-wave instability exists in certain parameter regimes which can lead to the formation of hexagonally ordered pores observed in anodized aluminum oxide. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,650 |
We study the Rayleigh instability of polystyrene (PS) thin films coated in the nanopores of anodic aluminum oxide (AAO) templates. After thermal annealing, the surface of the PS thin films undulates and the nanostructures transform from nanotubes to Rayleigh-instability-induced nanostructures (short nanorods with encapsulated air bubbles). With longer annealing times, the nanostructures further transform to nanorods with longer lengths. PS samples with two different molecular weights (24 and 100 kg/mol) are used, and their instability transformation processes are compared. The morphology diagrams of the nanostructures at different stages are also constructed to elucidate the mechanism of the morphology transformation. | Rayleigh instabilities in thin polymer films confined within nanoporous alumina membranes were studied. Thin films of poly(methyl methacrylate) (PMMA) were prepared by filling cylindrical nanopores in an anodic aluminum oxide (AAO) membrane with a PMMA solution in chloroform followed by solvent evaporation. When the PMMA nanotubes were annealed above the glass transition temperature (Tg), undulations in the film thickness were observed that were induced by a Rayleigh instability. The amplitude of the undulations increased with time and eventually bridged across the cylindrical nanopore in the AAO membrane, resulting in the formation of polymer nanorods with periodic encapsulated holes. A similar behavior was observed when PMMA films were confined within carbon nanotubes (CNTs). The Rayleigh instabilities in these confined geometries offer a novel means of controlling and fabricating the polymer nanostructures. These compartmentalized nanorods may have potential applications as delivery devices. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,651 |
The 2D janus hybrid (gold NPs/graphene) superstructures were built via a rapid, solventless sputtering method in 10 seconds. The size and morphology of gold NPs can be fine controlled by adjusting the sputtering current and time. The resulting graphene hybrids also enjoyed tunable area density and desirable thermal stability. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | Summary ::: ::: Morphological and molecular genetic analyses of the Aipenser gueldenstaedtii sensu Berg (1934) were accomplished using individuals collected in the southern part of the Caspian Sea. The distribution of specimens in the space of principal components were calculated using 28 morphometric characters. The results demonstrated the absence of separate clusters. Frequency distributions of six of the studied meristic characters were unimodal and did not reveal the existence of morphologically distinguishable forms within the analyzed sample. The molecular genetic analysis on polymorphism, based on D-loop and partial sequences of adjacent tRNA genes (total length about 956 bp) of the same samples demonstrated high homogeneity. Combining the results of morphological and molecular genetic studies of the Aipenser gueldenstaedtii sensu Berg (1934) do not support the validity of the existence of Persian sturgeon as a separate species Acipenser persicus. | eng_Latn | 11,652 |
Crystallisation behaviour of poly (ethylene oxide) (PEO) and isotactic polypropylene (iPP) on graphene surface was investigated by means of polarized microscopy, wide angle X-ray diffraction (WAXD), and Raman techniques. Results indicated that graphene influences the crystallisation and crystal structure of iPP and PEO. WAXD peaks shifting toward lower diffraction angle, i.e. increase in d-pacing, was observed in both PEO and iPP crystallised on the surface of graphene. The change of d-spacing of both PEO and iPP could result from the compressive stress caused by graphene. A shift of 2D band in graphene was observed from Raman spectra. The Raman spectra indicated the big shift in the 2D band is due to the presence of stress induced strain in the polymer attached graphene. The residual stress was generated during crystallization of the polymers on the surface of graphene. Due to the interactions between the graphene and the polymers, the stress was transferred to the graphene which leads to a strain of the graphene. Raman spectra proved the presence of stress generated by the crystallization of the polymers on the surface of graphene. | Nanocomposite strain sensors, particularly those consisting of polymer–graphene composites, are increasingly common and are of great interest in the area of wearable sensors. In such sensors, application of strain yields an increase in resistance due to the effect of deformation on interparticle junctions. Typically, widening of interparticle separation is thought to increase the junction resistance by reducing the probability of tunnelling between conducting particles. However, an alternative approach would be to use piezoresistive fillers, where an applied strain modifies the intrinsic filler resistance and so the overall composite resistance. Such an approach would broaden sensing capabilities, as using negative piezoresistive fillers could yield strain-induced resistance reductions rather than the usual resistance increases. Here, we introduce nanocomposites based on polyethylene oxide (PEO) filled with MoS2 nanosheets. Doping of the MoS2 by the PEO yields nanocomposites which are conductive enough to... | A nonlinear programming approach to the problem of learning in nonparametric and unsupervised environments is put forth in this study. The approach exploits the concept of optimal partitioning of the given data set as the objective of such nonparametric unsupervised learning. This partitioning or clustering is achieved by the application of the recently developed improved flexible polyhedron method (IFPM) to the associated optimization problem. The optimization problem is defined here in terms of a new, conceptually innovative optimality criterion based on intergroup and intragroup distinct scatters. Details of this new approach, a procedure for deriving an initial partition, and application of the algorithm to two numerical examples are presented. | eng_Latn | 11,653 |
The electrical conductance and principal structural and mechanical properties of gold nanowires, exhibiting reversibility in elongation-compression cycles at ambient conditions, were investigated using pin-plate experiments and molecular dynamics simulations. Underlying the reversible nature of the nanowires are their crystalline ordered structure and their atomistic structural transformation mechanisms, involving stages of stress accumulation and stress relief occurring through multiple-glide processes and characterized by a high critical yield stress value. {copyright} {ital 1996 The American Physical Society.} | The article examines the effect of atomic number, temperature and tempering time on microstructure and mechanical of Ni bulk by molecular dynamics simulation and deformation z-axis. Samples Ni with N = 4000, 5324, 6912, and 8788 atoms at 300 K, 6912 atoms at T = 1100, 900, 700, 500, 300 K and 6912 atoms at 900 K after different annealing time. The samples were incubated with the same heating rate . Combined with common neighborhood analysis method shown in sample is always existing four types structure: FCC, HCP, BCC, and Amor. In particular, structural units FCC, HCP and Amor always prevail and BCC are very small and appear only at 300, 500 K with 6912 atoms. When increasing atomic number, lowering temperature or increasing tempering time will facilitate crystallization process leading to increased FCC and HCP units number. The increasing FCC, HCP units number and additional appearance BCC structure led to change microstructure and mechanical of material: When increasing atom, lowering temperature and increasing incubation time lead to an increase in density of atoms that increase mechanical properties of the material. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,654 |
Unlike conventional dry stamp-based printing methodologies, the suggested wet PDMS stamping technique allows for the generation of well-patterned graphene source/drain electrode structures. It is clarified that the electrical characteristics of soluble In–Ga–Zn–O (IGZO) TFTs can be improved effectively by adjusting the work function of transfer-printed graphene electrodes with a simple, facile Au doping technique. By implementing the transfer-printed, Au-doped graphene layers as a source/drain electrode and the newly developed chemical structure-tailored IGZO semiconductors as a soluble channel layer, the high performance graphene/IGZO TFTs are demonstrated with a field-effect mobility of 3.2 cm2 V−1 s−1, which is far superior to the previously reported TFTs employing the printable electrode and a soluble oxide semiconductor. | In this study, a novel method based on the transfer of graphene patterns from a rigid or flexible substrate onto a polymeric film surface via solvent casting was developed. The method involves the creation of predetermined graphene patterns on the substrate, casting a polymer solution, and directly transferring the graphene patterns from the substrate to the surface of the target polymer film via a peeling-off method. The feature sizes of the graphene patterns on the final film can vary from a few micrometers (as low as 5 µm) to few millimeters range. This process, applied at room temperature, eliminates the need for harsh post-processing techniques and enables creation of conductive graphene circuits (sheet resistance: ~0.2 kΩ/sq) with high stability (stable after 100 bending and 24 h washing cycles) on various polymeric flexible substrates. Moreover, this approach allows precise control of the substrate properties such as composition, biodegradability, 3D microstructure, pore size, porosity and mechanical properties using different film formation techniques. This approach can also be used to fabricate flexible biointerfaces to control stem cell behavior, such as differentiation and alignment. Overall, this promising approach provides a facile and low-cost method for the fabrication of flexible and stretchable electronic circuits. | The effect of water exposure on amorphous indium-gallium-zinc oxide (a-IGZO) semiconductors was reported. It was found that water can diffuse in and out of the a-IGZO film, reversibly affecting the transistor properties. Two competing mechanisms depending on the thickness of the active channel were clarified. The electron donation effect caused by water adsorption dominated for the thicker a-IGZO films (⩾100nm), which was manifested in the large negative shift (>14V) of the threshold voltage. However, in the case of the thinner a-IGZO films (⩽70nm), the dominance of the water-induced acceptorlike trap behavior was observed. The direct evidence for this behavior was that the subthreshold swing was greatly deteriorated from 0.18V/decade (before water exposure) to 4.4V/decade (after water exposure) for the thinnest a-IGZO films (30nm). These results can be well explained by the screening effect of the intrinsic bulk traps of the a-IGZO semiconductor. | eng_Latn | 11,655 |
A challenge in organic thermoelectrics is to relate thermoelectric performance of devices to the chemical and electronic structures of organic components inside them on a molecular scale. To this end, a reliable and reproducible platform relevant to molecular-level thermoelectric measurements is essentially needed. This paper shows a new, efficient approach for thermoelectric characterization of a large area of molecular monolayers using liquid eutectic gallium–indium (EGaIn). A cone-shaped EGaIn microelectrode permits access to noninvasive, reversible top-contact formation onto organic surfaces in ambient conditions, high yields of working devices (up to 97%), and thus statistically sufficient thermoelectric data sets (∼6000 data per sample in a few hours). We here estimated thermopowers of EGaIn (3.4 ± 0.1 μV/K) and the Ga2O3 layer (3.4 ± 0.2 μV/K) on the EGaIn conical tip and successfully validated our platform with widely studied molecules, oligophenylenethiolates. Our approach will open the door to t... | As a derivative material of graphene, graphene oxide films hold great promise in thermal management devices. Based on the theory of Fourier formula, we deduce the analytical formula of the thermal conductivity of graphene oxide films. The interlaminar thermal property of graphene oxide films is studied using molecular dynamics simulation. The effect of vacancy defect on the thermal conductance of the interface is considered. The interfacial heat transfer efficiency of graphene oxide films strengthens with the increasing ratio of the vacancy defect. Based on the theoretical model and simulation results, we put forward an optimization model of the graphene oxide film. The optimal structure has the minimum overlap length and the maximum thermal conductivity. An estimated optimal overlap length for the GO (graphene-oxide) films with degree of oxidation 10% and density of vacancy defect 2% is 0.33 μm. Our results can provide effective guidance to the rationally designed defective microstructures on engineering thermal transport processes. | Blunt trauma abdomen rarely leads to gastrointestinal injury in children and isolated gastric rupture is even rarer presentation. We are reporting a case of isolated gastric rupture after fall from height in a three year old male child. | eng_Latn | 11,656 |
The temperature dependence of the saturation magnetization of a series of ionimplanted YIG films is presented. The films were implanted with neon ions at an energy of 450 keV; the dose ranged from 2 to 5*1014 ions/cm2. The experimental data can be described by the molecular field theory showing that the ion-implanted part of the film can be approximated as consisting of two regions each having their own magnetization and Curie temperature. The values of these magnetic parameters vary as a function of dose and differ strongly from the values for pure YIG. | We report that in an in-plane magnetised magnetic film the in-plane direction of a propagating spin wave can be changed by up to 90 degrees using an externally induced magnetic gradient field. We have achieved this result using a reconfigurable, laser-induced magnetisation gradient created in a conversion area, in which the backward volume and surface spin-wave modes coexist at the same frequency. Shape and orientation of the gradient control the conversion efficiency. Experimental data and numerical calculations agree very well. Our findings open the way to magnonic circuits with in-plane steering of the spin-wave modes. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,657 |
Plasmonic properties of metal nanomaterials critically affect on thermal treatments. One of such effects is ‘plasmonic-bleaching’ observed in ‘atom beam co-sputtering’ derived Ag:TiO 2 nanocomposite thin films, when annealed at 450 °C. The origin of bleaching is investigated using glancing angle X-ray diffraction and Rutherford backscattering spectroscopy. The kinetics of Ag nanoparticles during the deposition and after thermal treatment is presented to understand involved host-matrix interactions. Based on Rutherford Materials Program simulation, possible mechanism of bleaching is presented. | A polarization-independent gas sensor based on crescent plasmonic dipole antenna loaded with graphene monolayer is introduced in this paper for environment monitoring applications. Single, dual, and four arms crescent dipoles are designed, analyzed and investigated. The proposed gas sensor has reconfigurable absorption characteristics in the wavelength range from 900 to 1600 nm which covers the different gases responses. A parametric study on the effect of the sensor dimensions and polarization of the illuminated waves on the total absorption of different gases is investigated. A graphene monolayer is used to enhance the gas molecule absorption in its unbiased state. An enhancement of the total absorption cross section (ACS) values for n = 1.4 is 1.028 × 105 nm2 for the unloaded sensor case and is 1.77 × 105 for the graphene loaded sensor case. The unloaded graphene sensor sensitivity is 630 nm/RIU, and for the graphene loaded case is 677.5 nm/RIU. Dual-polarized crescent dipole consists of two orthogonal arms is designed to maintain the same sensitivity for x- and y-polarized E-field illumination. A polarization independent gas sensor consists of four crescents dipole arms rotated with 45° is explained. An enhancement of gas absorption is achieved by using a sensor array of four-arm dipole sensor. Different array sizes loaded with graphene monolayer are investigated. The total ACS peak value is 7.84 × 106 nm2 for 6 × 6 dipole array is obtained. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,658 |
We examine the issue of stability of probability in reasoning about complex systems with uncertainty in structure. Normally, propositions are viewed as probability functions on an abstract random graph where it is implicitly assumed that the nodes of the graph have stable properties. But what if some of the nodes change their characteristics? This is a situation that cannot be covered by abstractions of either static or dynamic sets when these changes take place at regular intervals. We propose the use of sets with elements that change, and modular forms are proposed to account for one type of such change. An expression for the dependence of the mean on the probability of the switching elements has been determined. The system is also analyzed from the perspective of decision between different hypotheses. Such sets are likely to be of use in complex system queries and in analysis of surveys. | Some ideas around 3n+1 iterations.- Analysis of the Collatz graph.- 3-adic averages of counting functions.- An asymptotically homogeneous Markov chain.- Mixing and predecessor density. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,659 |
A review is given of the results of investigations of the channelling of high-energy charged particles in bent single crystals carried out in the last fifteen years. These investigations have given rise to new applications of crystals in the control of high-energy particle beams in modern accelerators: in beam lines, in systems for the extraction of accelerated beams, and in certain experiments. | Beam steering performance of bent silicon crystals irradiated with high-intensity and high-energy protons has been studied. In particular, crystals of the type used for collimation and extraction purposes in the Large Hadron Collider and the Super Proton Synchrotron at CERN have been irradiated at the HiRadMat CERN facility with $$2.5 \times 10^{13}$$ 440 GeV/c protons, with a pulse length of 7.2 $$\upmu $$s. The purpose is to study possible changes in bending angle and channeling efficiency due to thermo-mechanical stresses in case of accidental irradiation during accelerator operations. A comparison between measurements performed before and after the irradiation does not show any appreciable performance reduction in either crystal. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,660 |
Semi-discretization method is expanded to determine the stability charts of NFDE for milling processes including process damping. The method is based on a special kind of discretization technique with respect to the past effect only. The convergence of approximate method is investigated by the example of delayed Mathieu equation, and stability charts of the damped and neutral delayed Mathieu equation for different time-period/time delay ratios are determined. The results show that, semi-discretization method can be employed to predict the stability of milling processes including process damping. | A cooling package for an automobile passenger compartment including a housing which encloses an evaporator core and a motor driven fan having rotatable air outlets to permit alternate horizontal or vertical mounting of the package within the automobile. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,661 |
The scientist‐practitioner philosophy of clinical practice is first placed in its historical context. The history of the scientist‐practitioner stance is marked by an enduring struggle between advocates and opponents of a research-based profession of clinical psychology. The criticisms of the scientist‐practitioner stance are discussed alongside counterarguments in support of that position. Making the conceptual distinction between theoretical preference and philosophical position, three philosophies to underpin clinical psychology are outlined. It is concluded that the fundamental research to decide on the optimum stance for effective practice, and hence to inform training, is sadly lacking. # 1997 by John Wiley & Sons, Ltd. | Sixty-two members of staff from clinical psychology doctoral training programmes across Britain completed a survey about their level of research output, the extent to which they felt this met their own expectations and job requirements, and how it influenced promotion prospects. In addition, they listed perceived barriers to and facilitators of research activity. There was wide variation in research activity, such that many participants had limited or no publications while a smaller proportion had many. Respondents were as, or more, dissatisfied than satisfied with their publications, submissions and grant applications and over half felt that the number of grant applications failed to meet their expectations. Support from and collaboration with colleagues was the main facilitator for research, while a lack of time was viewed as the main barrier. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,662 |
Quantum dots (QDs) integrated 2-dimensional (2D) materials have great potential for photodetector applications due to the excellent light absorption of QDs and ultrafast carrier transportation of 2D materials. However, there is a main issue that prevents efficient carrier transportation and ideal performance of photodetectors: the high interfacial resistance between 2D materials and QDs due to the bad contacts between 2D/0D interface, which makes sluggish carrier transfer from QDs to 2D materials. Here, a sandwich structure (graphene/PbS-QDs/graphene) with seamless 2D/0D contact was fabricated by laser shock imprinting, which opto-mechanically tunes the morphology of 2D materials to perfectly wrap on 0D materials and efficiently collect carriers from the PbS-QDs. It is found that this seamless integrated 2D/0D/2D structure significantly enhanced the carrier transmission, photoresponse gain (by 2×), response time (by 20×), and photoresponse speed (by 13×). The response time (∼30 ms) and Ip/ Id ratio (13.2) are both over 10× better than the reported hybrid graphene photodetectors. This is due to the tight contact and efficient gate-modulated carrier injection from PbS-QDs to graphene. The gate voltage dictates whether electrons or holes dominate the carrier injection from PbS-QDs to graphene. | Hybrid lead chalcogenide (PbE) (E = S, Se) quantum dot (QD)-layered 2D systems are an emerging class of photodetectors with unique potential to expand the range of current technologies and easily integrate into current complementary metal-oxide-semiconductor (CMOS)-compatible architectures. Herein, we review recent advancements in hybrid PbE QD-layered 2D photodetectors and place them in the context of key findings from studies of charge transport in layered 2D materials and QD films that provide lessons to be applied to the hybrid system. Photodetectors utilizing a range of layered 2D materials including graphene and transition metal dichalcogenides sensitized with PbE QDs in various device architectures are presented. Figures of merit such as responsivity (R) and detectivity (D*) are reviewed for a multitude of devices in order to compare detector performance. Finally, a look to the future considers possible avenues for future device development, including potential new materials and device treatment/fabrication options. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,663 |
The arrangement of atoms in an atomically clean (011) iron surface, and the chemisorption of oxygen atoms, and subsequent formation of a discrete thin crystalline oxide film on this surface have been investigated by low-energy electron diffraction (LEED). ::: ::: These data indicated that an atomically clean (011) surface of iron is an unreconstructed surface, in which the surface iron atoms are situated in the same crystal-lattice positions as the iron atoms in an equivalent crystallographic plane lying in the bulk of the crystal. Furthermore, the interplanar spacing between the top several layers of atoms was found to be identical to that in the bulk of the crystal, in agreement with theoretical considerations. When the clean (011) surface was allowed to interact with oxygen in the low-pressure range of about 10−8 Torr, the oxygen atoms sorbed on this surface first were arranged in an ordered, c(2 × 2) 2-dimensional (2D) mesh comprising one quarter of a monolayer of oxygen atoms. With continued exposure to this low oxygen pressure, patterns consistent with two-thirds and finally a “full” monolayer of oxygen coverage were observed. Upon ultra-high-vacuum annealing the oxygen monolayer was believed to reconstruct to form a 3-dimensional (3D) oxide precursor, which contained both oxygen and iron ions in the top layer. After a still greater oxygen exposure in the 10−6 Torr range, at room temperature, a LEED pattern was observed that was consistent with two orientations of a (111) plane of FeO rotated 180° with respect to each other and parallel to the (011) plane of the substrate iron. Since no change in the LEED oxide pattern was observed after an extended period of time at a low-oxygen partial pressure (< 10−13 Torr), it was concluded that this thin oxide film was stable or that it grew as FeO. | Two-dimensional (2D) materials have attracted interest because of their excellent properties and potential applications. A key step in realizing industrial applications is to synthesize wafer-scale single-crystal samples. Until now, single-crystal samples, such as graphene domains up to the centimeter scale, have been synthesized. However, a new challenge is to efficiently characterize large-area samples. Currently, the crystalline characterization of these samples still relies on selected-area electron diffraction (SAED) or low-energy electron diffraction (LEED), which is more suitable for characterizing very small local regions. This paper presents a highly efficient characterization technique that adopts a low-energy electrostatically focused electron gun and a super-aligned carbon nanotube (SACNT) film sample support. It allows rapid crystalline characterization of large-area graphene through a single photograph of a transmission-diffracted image at a large beam size. Additionally, the low-energy electron beam enables the observation of a unique diffraction pattern of adsorbates on the suspended graphene at room temperature. This work presents a simple and convenient method for characterizing the macroscopic structures of 2D materials, and the instrument we constructed allows the study of the weak interaction with 2D materials. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,664 |
We investigate electrical conduction and breakdown behavior of 3D nano-carbon-stacked multilayer graphene (s-MLG) system with complete interlayer decoupling. The s-MLG is prepared by transferring and stacking large-area CVD-grown graphene monolayers, followed by wire patterning and plasma etching. Raman spectroscopy was used to confirm the layer number. The D-band peak indicates low defect level in the samples. Electrical current stressing induced doping is performed to shift the charge-neutrality Dirac point and decrease the graphene/metal contact resistance, improving the overall electrical conduction. Breakdown experiments show the current-carrying capacity of s-MLG is largely enhanced as compared with that of monolayer graphene. | The diffusion processes and kinetic barriers of individual carbon adatoms and clusters on graphene surfaces are investigated to provide fundamental understanding of the physics governing epitaxial growth of multilayer graphene. It is found that individual carbon adatoms form bonds with the underlying graphene whereas the interaction between graphene and carbon clusters, consisting of 6 atoms or more, is very weak being van der Waals in nature. Therefore, small carbon clusters are quite mobile on the graphene surfaces and the diffusion barrier is negligibly small (∼6 meV). This suggests the feasibility of high-quality graphene epitaxial growth at very low growth temperatures with small carbon clusters (e.g., hexagons) as carbon source. We propose that the growth mode is totally different from 3-dimensional bulk materials with the surface mobility of carbon hexagons being the highest over graphene surfaces that gradually decreases with further increase in cluster size. | Adenomyoepithelioma is thought to be a low-grade malignancy, and cases showing malignant behavior are rare. | eng_Latn | 11,665 |
CONTENTS 1. Introduction 455 2. Formation of Statistical System in the Process of Fast-hadron Collision 460 3. Fundamental Formulas of the Statistical Theory of Multiple Generation 464 4. Characteristics of the Multiple Generation Process (Comparison with Experiment) 465 5. Statistical Large-angle Scattering 474 6. Fundamental Problems of Statistical Theory. Dynamics and "True Statistics" 479 7. Conclusion 480 Supplement. Statistical Model with Lorentz-invariant Phase Volume 481 Cited literature 481 | I describe studies done by the theory group of Lebedev Physical Institute in Moscow and point out the cross-influence of some of our work with that of Rolf Hagedorn, and show how this research continued and evolved up to the present. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,666 |
In this article, we attempted a study on field effect transport characteristics of graphene flakes. These graphene flakes were exfoliated by mechanical peeling-off technique and the electrical contacts were patterned by photo-lithographic method. Graphene devices have shown better transfer characteristics which was obtained even in low-voltage (< 5 V). Back-gated graphene transistors were patterned on oxidized silicon wafers. A clear n-type to p-type transition at Dirac point and higher electron drain-current modulation in positive back-gate field with current minimum (the Dirac point) were observed at V(GS) = -1.7 V. The carrier mobility was determined from the measured transconductance. The transconductance of the graphene transistors was observed as high as 18.6 microS with a channel length of 68 microm. A maximum electron mobility of 1870 +/- 143 cm2/V x s and hole mobility of 1050 +/- 35 cm2/V x s were achieved at a drain bias 2.1 V which are comparatively higher values among reported for mechanically exfoliated graphene using lithographic method. The fabricated devices also sustained with high-current density for 40 hr in continuous operation without any change in device resistance, which could be applied for robust wiring applications. | We study the impact of hot-carrier degradation (HCD) on the performance of graphene field-effect transistors (GFETs) for different polarities of HC and bias stress. Our results show that the impact of HCD consists in a change of both charged defect density and carrier mobility. At the same time, the mobility degradation agrees with an attractive/repulsive scattering asymmetry and can be understood based on the analysis of the defect density variation. | The oxidative polymorphism of debrisoquine (DBQ) has been determined in 89 patients with colo-rectal cancer and in 556 normal control subjects. Four patients and 34 controls, with a metabolic ratio >12.6, were classified as poor metabolisers of DBQ (n.s.). | eng_Latn | 11,667 |
Waviness is invariably present in vertically-aligned Carbon Nanotubes (CNTs) regardless of how controlled the fabrication process is. This study, using experiments and models, shows that such inherent waviness is the main mechanism by which the effective modulus of CNTs is reduced by several orders of magnitude. At this time, most studies have shown that the compliant mechanical response of the CNT forests under compressive loading is due to bending and buckling of CNTs as well as the variation of CNT density throughout the forest height. Subjecting CNT forests to tensile loads as well as to compressive loads, it is shown here that the high compliance of CNT forests is due to the inherent waviness of individual CNTs, and not necessarily due to bending and buckling of CNTs. The experimental findings are also supported through analytical models and numerical models that show that the CNT wavy geometry causes the CNTs to have 4–5 orders of magnitude greater compliance than a straight CNT. | Stretchable and transparent electrodes have been developed for applications in flexible and wearable electronics. For customer-oriented practical applications, the electrical and optical properties of stretchable electrodes should be independent of the directions of the applied stress, and such electrodes are called omnidirectionally stretchable electrodes. Herein, we report a simple and cost-effective approach for the fabrication of omnidirectionally stretchable and transparent graphene electrodes with mechanical durability and performance reliability. The use of a Fresnel lens-patterned electrode allows multilayered graphene sheets to achieve a concentric circular wavy structure, which is capable of sustaining tensile strains in all directions. The as-prepared electrodes exhibit high optical transparency, low sheet resistance, and reliable electrical performances under various deformation (e.g., bending, stretching, folding, and buckling) conditions. Furthermore, computer simulations have also been carr... | Floating catalyst chemical vapor deposition uniquely generates aligned carbon nanotube (CNT) textiles with individual CNT lengths magnitudes longer than competing processes, though hindered by impurities and intrinsic/extrinsic defects. We present a photonic-based post-process, particularly suited for these textiles, that selectively removes defective CNTs and other carbons not forming a threshold thermal pathway. In this method, a large diameter laser beam rasters across the surface of a partly aligned CNT textile in air, suspended from its ends. This results in brilliant, localized oxidation, where remaining material is an optically transparent film comprised of few-walled CNTs with profound and unique improvement in microstructure alignment and crystallinity. Raman spectroscopy shows substantial D peak suppression while preserving radial breathing modes. This increases the undoped, specific electrical conductivity at least an order of magnitude to beyond that of single-crystal graphite. Cryogenic conductivity measurements indicate intrinsic transport enhancement, opposed to simply removing nonconductive carbons/residual catalyst. | eng_Latn | 11,668 |
In this work, we provide some novel analytic and finite element solutions to the Euler–Bernoulli equation for graphene beams. Comparisons of the solutions and error analysis are demonstrated. | We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The force-displacement behavior is interpreted within a framework of nonlinear elastic stress-strain response, and yields second- and third-order elastic stiffnesses of 340 newtons per meter (N m –1 ) and –690 Nm –1 , respectively. The breaking strength is 42 N m –1 and represents the intrinsic strength of a defect-free sheet. These quantities correspond to a Young9s modulus of E = 1.0 terapascals, third-order elastic stiffness of D = –2.0 terapascals, and intrinsic strength of σ int = 130 gigapascals for bulk graphite. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 11,669 |
The mechanisms leading to initiation of electrical breakdown in geometrically identical argon-filled tubes at different pressures were investigated by the memory curves. It was shown that the positive ions and metastable states, remaining from the previous discharge, have the dominant role in the initiation of breakdown in early and late afterglow periods, respectively. Contributions to the breakdown of gamma photons from radioactive sources (60Co) and cosmic rays were also analyzed. | The connection between nonhomogeneities of the electric field and the value of the breakdown voltage [direct current (dc), pulls] in gases (N/sub 2/, SF/sub 6/) under low pressure and small inter-electrode gap was investigated in this paper. The obtained results show that the values of the breakdown voltages for nonhomogenous fields are considerably higher than the values for homogenous fields. It was also established that there is some disagreement between experimentally and theoretically (numerically) obtained values of the dc breakdown voltages for nonhomogenous fields. These results could be explained by the small distance effect and by the combination of the gas and vacuum breakdown mechanisms. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,670 |
We have studied the influence of SiO2 and TiO2 dielectric layers on the atomic intermixing of InxGa1−xAs/InP quantum well structures using the impurity-free vacancy disordering technique. Photoluminescence results revealed that an enhancement of interdiffusion was obtained when the samples were capped with SiO2. Although TiO2 layers were able to suppress the interdiffusion in the InGaAs/InP system, the suppression was not significant compared to the AlGaAs/GaAs system. Based on a fitting procedure that was deconvoluted from the photoluminescence spectra as well as a theoretical modeling, the electron–heavy hole and electron–light hole transitions were identified, and a ratio of the group V to the group III diffusion coefficients (k) was obtained. The k ratio of the InGaAs/InP samples capped with SiO2 is relatively larger than that of samples capped with TiO2 layers. | We increased the Al content in the single quantum well InGaP/InAlGaP laser by strain-induced quantum well intermixing, and obtained a considerable enhancement (close to ten-fold increase) in the photoluminescence (PL) intensity. Among the annealing process investigated, we achieved lasing at 638 nm in conjunction with reduction in the lasing threshold current by close to 500 mA in a moderately intermixed laser. Lasing in orange color, as well as spontaneous emission in the yellow and green color regime, were also achieved by extending the annealing conditions. The significance of the current work became apparent when one considers that achieving these tunable wavelengths by increasing the Al content in quantum wells during epitaxy growth leads to severe lattice-mismatch and poor material quality. Hence, our Al "drive-in" intermixing process is a viable approach for forming Al-rich InAlGaP quantum well, which is essential for realizing efficient optoelectronic devices in the "green-yellow-orange gap". | Composites consisting of graphene nanosheets (GNSs) decorated with amorphous TiO 2 thin films were synthesized by an atomic layer deposition (ALD) technique. It was revealed that the TiO 2 thin films were uniformly deposited onto the worm-like GNSs. When used as anode materials in lithium ion batteries (LIBs), the TiO 2 –GNS composites deliver a stable capacity of ~ 140 mAh g − 1 after 100 cycles at a specific current of 100 mA g − 1 as well as superior rate capability, accounting for a sustainable 95 mAh g − 1 capacity at a specific current of 1200 mA g − 1 . It is believed that the remarkable electrochemical performance lied in the unique features of the composites, i.e., the amorphous nature of the TiO 2 films and the large surface area of GNSs. The former rendered short Li + diffusion pathways in TiO 2 thin film, while the latter offered excellent electronic conductivity as well as a large intimate contact area between the electrolyte and TiO 2 . This work laid a venue for designing new electrodes for high-performance LIBs. | eng_Latn | 11,671 |
A theoretical study based on first-principles calculations about the interaction and diffusion of Ni atoms on pristine graphene and graphene with a single vacancy is presented. In the first case, we explored the structural changes due to the adsorption of Ni on graphene and the effects on the electronic structure. In the case of graphene with a vacancy, we analyzed the impact of the adsorbed Ni atom on the distortion of the graphene structure and how it depends on the distance from the graphene defect. In the analysis, we observed the changes in the electron localization function and the charge density. By knowing the interaction map of Ni with graphene, and the structural changes of the network, we performed energy barrier calculations within the climbing image nudged elastic band methodology to study the nickel diffusion. Finally, we explored how the vacancy and structural distortions affect the minimum energy paths and the saddle points for nickel moving away, around, and towards the vacancy. | The problem of finding minimum energy paths and, in particular, saddle points on high dimensional potential energy surfaces is discussed. Several different methods are reviewed and their efficiency compared on a test problem involving conformational transitions in an island of adatoms on a crystal surface. The focus is entirely on methods that only require the potential energy and its first derivative with respect to the atom coordinates. Such methods can be applied, for example, in plane wave based Density Functional Theory calculations, and the computational effort typically scales well with system size. When the final state of the transition is known, both the initial and final coordinates of the atoms can be used as boundary conditions in the search. Methods of this type include the Nudged Elastic Band, Ridge, Conjugate Peak Refinement, Drag method and the method of Dewar, Healy and Stewart. When only the initial state is known, the problem is more challenging and the search for the saddle point represents also a search for the optimal transition mechanism. We discuss a recently proposed method that can be used in such cases, the Dimer method. | The self-healing mechanism of radiation-induced defects in nickel–graphene nanocomposite is investigated by atomistic simulations. Compared with pure nickel, nickel–graphene nanocomposite has less defects remained in the bulk region after collision cascades, illustrating self-healing performance. Nickel–graphene interfaces (NGIs) serve as sinks for radiation-induced defects and preferentially trap interstitials over vacancies. Energetic and kinetic calculations reveal that the defect formation energy and diffusion barrier are reduced in the vicinity of NGIs, and the reduction are pronounced for interstitials. When NGIs are loaded with interstitials, their segregation ability on radiation-induced defects improves significantly, and the radiation-induced defects near the NGIs diffuse more easily. Especially, the vacancies (or interstitials) near the NGIs tend to annihilate (or aggregate) with the interstitials trapped at the NGIs, which only happens at the interstitial-loaded side of NGIs. Therefore, nickel–graphene nanocomposite exhibits excellent radiation tolerance and shows promise as a structural material for advanced nuclear reactors due to its NGIs with the energetic and kinetic driving forces acting on radiation-induced defects. | eng_Latn | 11,672 |
In this paper, functionalized single walled carbon nanotubes (FSWCNTs) were suspended in Ethylene Glycol (EG) at different volume fractions. A KD2 pro thermal conductivity meter was used to measure the thermal conductivity in the temperature range from 30 to 50 °C. Nanofluids were prepared in solid volume fraction of 0.02, 0.05, 0.075, 0.1, 0.25, 0.5 and, 0.75%. Experimental results revealed that the thermal conductivity of the nanofluid is a non-linear function of temperature and SWCNTs volume fraction in the range of this investigation. Thermal conductivity increases with temperature and nanoparticles volume fraction as usual for this type of nanofluid. Maximum increment in thermal conductivity of the nanofluids was found to be about 45% at 0.75 vol fractions loading at 50 °C. Finally, a new correlation based on artificial neural network (ANN) approach has been proposed for SWCNT-EG thermal conductivity in terms of nanoparticles volume fraction and temperature using the experimental data. Used ANN approach has estimated the experimental values of thermal conductivity with the absolute average relative deviation lower than 0.9%, mean square error of 3.67 × 10 −5 and regression coefficient of 0.9989. Comparison between the suggested techniques with various used correlation in the literatures established that the ANN approach is better to other presented methods and therefore can be proposed as a useful means for predicting of the nanofluids thermal conductivity. | Nanofluids have attracted the attention of researchers in recent years considerably. Due to the increasing number of articles on nanofluids, they need to be reviewed. Thermal conductivity is one of the most important properties of nanofluids. There are many methods for preparing nanoparticles and nanofluids that are used by numerous researchers in their experimental studies. There are also several different approaches to measure nanoparticles thermal conductivity (NPTC). In this article, the methods for preparing nanoparticles are discussed. Further, nanofluid preparation methods are studied. Subsequently, the papers in which NPTC has been considered are briefly reviewed and some explanations are provided for hybrid nanofluids. Finally, a variety of methods for measuring NPTC are considered. In existing methods, the hot-wire method is the most widely used, and most researchers have employed this method to measure the NPTC. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,673 |
Edge-dependent electronic properties of graphene nanoribbons (GNRs) have attracted intense interests. To fully understand the electronic properties of GNRs, the combination of precise structural characterization and electronic property measurement is essential. For this purpose, two experimental techniques using free-standing GNR devices have been developed, which leads to the simultaneous characterization of electronic properties and structures of GNRs. Free-standing graphene has been sculpted by a focused electron beam in transmission electron microscope (TEM) and then purified and narrowed by Joule heating down to several nanometer width. Structure-dependent electronic properties are observed in TEM, and significant increase in sheet resistance and semiconducting behavior become more salient as the width of GNR decreases. The narrowest GNR width we obtained with the present method is about 1.6 nm with a large transport gap of 400 meV. | We report the etching of and electronic transport in nanoribbons of graphene sandwiched between atomically flat hexagonal boron nitride (h-BN). The etching of ribbons of varying width was achieved with a focused beam of 30 keV He+ ions. Using in-situ electrical measurements, we established a critical dose of 7000 ions nm−2 for creating a 10 nm wide insulating barrier between a nanoribbon and the rest of the encapsulated graphene. Subsequently, we measured the transport properties of the ion-beam etched graphene nanoribbons. Conductance measurements at 4 K show an energy gap, that increases with decreasing ribbon width. The narrowest ribbons show a weak dependence of the conductance on the Fermi energy. Furthermore, we observed power-law scaling in the measured current-voltage (I-V) curves, indicating that the conductance in the helium-ion-beam etched encapsulated graphene nanoribbons is governed by Coulomb blockade. | Blunt trauma abdomen rarely leads to gastrointestinal injury in children and isolated gastric rupture is even rarer presentation. We are reporting a case of isolated gastric rupture after fall from height in a three year old male child. | eng_Latn | 11,674 |
In this paper, the H ∞ state estimation problem for networked systems with Markov interval delay characteristic is investigated. A Markov chain is introduced to describe the delayed networked systems, considering the difficulty of obtaining the ideal knowledge of all transition probabilities, and a Markovian jump systems model with partially unknown transition probabilities is established. Based on the obtained new model, by utilizing observer as state estimation generator, the addressed state estimation problem is converted into H ∞ attenuation problem. Then, with the help of stochastic Lyapunov-Krasovskii functional approach, the sufficient condition for the desired mode-dependent observer is constructed in terms of linear matrix inequalities, which depend on not only delay interval but also partially known transition probabilities. The effectiveness of the proposed method is demonstrated by simulation example. | This paper focuses on stability and stabilization for a class of continuous-time Markovian jump systems with partial information on transition probability. The free-connection weighting matrix method is proposed to obtain a less conservative stability criterion of Markovian jump systems with partly unknown transition probability or completely unknown transition probability. As a result, a sufficient condition for the state feedback controller design is derived in terms of linear matrix inequalities. Finally, numerical examples are given to illustrate the effectiveness and the merits of the proposed method. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,675 |
We report the structural and optical properties of Au nanoparticles embedded in a silica matrix synthesized by atom beam co-sputtering. The presence of surface plasmon resonant absorption indicates the formation of Au nanoparticles. Transmission electron microscopy (TEM) studies show the presence of Au nanoparticles with an average size ranging from ~1.8 to 5.4 nm with narrow size distributions depending on the relative areas of Au and SiO2. We discuss the process of nucleation and growth of Au nanoparticles in the nanocomposite films formed by co-sputtering. The present method of nanoparticle synthesis is compared with other ion beam based techniques such as ion implantation and ion beam mixing. Preliminary experiments for the detection of human ovarian cancer cells using these Au nanoparticles are described. | Chemotherapy, the most commonly used therapeutic method for cancer, has the inherent constraint of low bioavailability. A number of physical cancer therapeutic treatments like radiation, ultrasound, photo-acoustic/photo thermal, microwave therapies are based on locating the afflicted sites with the help of imaging, but the serious drawbacks of these treatment options are that they damage the neighboring normal tissues and/or induce undesired cancer metastasis. In addition, these methods of treatment are very expensive and not in the reach of a common man especially in the developing countries. Therefore, innovative, less invasive and cost effective treatment methods with the help of less toxic drugs have been sought for treating cancer. In this work, photo-catalytic method of killing cancer cells, using the nanostructured silver loaded tungsten oxide (Ag/WO3) as photo-catalysts, in conjunction with broadband UV radiation is presented. Ag/WO3with two different mass ratios of Ag and WO3 (1% Ag/WO3 and 3% Ag/WO3) were synthesized, characterized and these nanostructured materials served as photo-catalysts in the process of killing cancer cells by photo-catalytic method. The advantage of loading Ag in WO3 is quite evident from the observed increase in the photo-catalytic killing of the HeLa cells. This photo-catalytic enhancement was effectively caused by the development of Schottky junction between Ag in WO3, which led to a substantial inhibition of photo-generated charge recombination and also by the stimulation of surface plasmon resonance in silver nanoparticles, which led to the enhanced visible light absorption by the material. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,676 |
In this work, we present a recursive Green’s function method to calculate electronic transport of armchair graphene nanoribbon (AGNR) and zigzag graphene nanoribbons (ZGNRs) quantum wires with randomly adsorption of monatomic gas molecules, which attached to two semi-infinite metallic leads. This model reduces numerical calculations time and enables us to use Green’s function method to investigate transport in a supperlattice device. The calculations based on the Landauer-type formula within the tight-binding approximation, which the recursive Green’s function method is used to solve inhomogeneous differential equations. The effects of monatomic gas molecules adsorption on electronic conductance properties are studied for various length and wide size of wire. Our numerical results show that the transport properties are strongly affected by the quantum interference effect, the lead interface geometry to the device and also adsorption of gas molecules on GNR sheets. By controlling the type of contact and wire geometry, this kind of system can explain the antiresonance states at the Fermi energy. The results can be used to control and engineer the graphene-based systems. | 539 ABSTRACT: Disordered T-shaped graphene nanodevice (TGN) was designed and studied in this paper. We demonstrated the intrinsic transport properties of the TGN by using Landauer approach. Knowing the transmission probability of an electron the current through the system is obtained using Landauer-Buttiker formalism. The effects of single disorder on conductance, current and on the transport length scales are studied using tight-binding model. It is demonstrated that the transport property of the TGN depends sensitively on the disorder positions. However, the current slightly depends on the disorder sites, but strongly depends on the geometry of TGN under small bias voltage. The mean free path in the system is reduced when the strength of disorder is sufficiently high and the mean free path patterns are found to strongly depend on the disorder position. Also observe that the current basically decreases with the stem height increase. We have found that zigzag graphene nanoribbons can be used as metal leads when we build graphene nanodevice based electronic devices. | Blunt trauma abdomen rarely leads to gastrointestinal injury in children and isolated gastric rupture is even rarer presentation. We are reporting a case of isolated gastric rupture after fall from height in a three year old male child. | eng_Latn | 11,677 |
Microstructural evolutions during annealing of a plastically deformed AISI 304 stainless steel were investigated. Three distinct stages were identified for the reversion of strain-induced martensite to austenite, which were followed by the recrystallization of the retained austenite phase and overall grain growth. It was shown that the primary recrystallization of the retained austenite postpones the formation of an equiaxed microstructure, which coincides with the coarsening of the very fine reversed grains. The latter can effectively impair the usefulness of this thermomechanical treatment for grain refinement at both high and low annealing temperatures. The final grain growth stage, however, was found to be significant at high annealing temperatures, which makes it difficult to control the reversion annealing process for enhancement of mechanical properties. Conclusively, this work unravels the important microstructural evolution stages during reversion annealing and can shed light on the requirements and limitations of this efficient grain refining approach. | Diffraction Geometry and the X-Ray Powder Diffractometer.- The TEM and Its Optics.- Scattering.- Inelastic Electron Scattering and Spectroscopy.- Diffraction from Crystals.- Electron Diffraction and Crystallography.- Diffraction Contrast in TEM Images.- Diffraction Lineshapes.- Patterson Functions and Diffuse Scattering.- High Resolution TEM Imaging.- Dynamical Theory.- Appendix. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,678 |
A theoretical study is presented of the effect of misfit strain on the transition from step flow to island nucleation dominated epitaxial layer growth on a vicinal surface. The analysis generalizes a set of reaction‐diffusion equations used for homoepitaxy to include the fact that heteroepitaxial strain changes the Arrhenius barrier for diffusion and promotes the detachment of atoms from the edge of strained terraces and islands. The first effect is equivalent to changing the deposition flux; the latter can drive the system into a new layer growth mode characterized by moving steps that engulf very many very small islands. Experiments to test these predictions are suggested. | Large-scale growth of single crystals on graphene can be useful for the development of 3D/2D or 2D/2D heterostructures. Here, through careful control of growth kinetics, the authors perform multiple cycles of direct growth/transfer of high-quality single-crystal GaN, using a single graphene/SiC substrate. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 11,679 |
The dependence of field emission properties of titanium dioxide (TiO2) nanotubes (NTs) has been studied as a function of NT diameter (D) and height (h), which varied in the ranges 18–500 nm and 500–12 000 nm, respectively. The studies showed a strong dependence of the field emission on these parameters. With an increase of NT diameter, the field enhancement factor increased monotonically from 120 to 3800; the current density also increased until D = 320 (current density ~ 3.8 mA cm − 2), with subsequent decrease for larger diameters. The field emission properties initially improved with NT height until h = 5 µm, and later remained unchanged with further increases in h. | TiO2 nanowires with rutile structures on a SiO2/Si substrate were grown by thermal evaporation. A field-emission property of the low turn-on field was reduced to 3.5 and 2.6 V/μm under UVA in 10 min and UVC in 25 min. The wavelength of UVC was higher than the TiO2 band-gap, so the electrons more easily tunneled to the vacuum level and generated excess heat that lowered the turn-on field emission from under UVA. The work function of samples that had been exposed to UVA for 10 min and UVC for 25 min were reduced to 3.10 and 2.02 eV, respectively. | We demonstrate the use of nanoimprint lithography as an alternative low-cost fabrication route for the production of ordered arrays of individual carbon nanotube field emitters. A high emission site density of 4×105cm−2 was observed and is well within the specification of the cathode for a field emission display. The measured field enhancement values from the geometry of the nanotubes were in reasonable agreement with the values obtained through electrical measurements. We also show that the distribution of the field enhancement factor is Gaussian, indicative of the presence of well ordered arrays of carbon nanotube field emitters. | eng_Latn | 11,680 |
3D fluorescence microscopy of living organisms has increasingly become an essential and powerful tool in biomedical research and diagnosis. An exploding amount of imaging data has been collected, whereas efficient and effective computational tools to extract information from them are still lagging behind. This is largely due to the challenges in analyzing biological data. Interesting biological structures are not only small, but are often morphologically irregular and highly dynamic. Although tracking cells in live organisms has been studied for years, existing tracking methods for cells are not effective in tracking subcellular structures, such as protein complexes, which feature in continuous morphological changes including split and merge, in addition to fast migration and complex motion. In this paper, we first define the problem of multi-object portion tracking to model the protein object tracking process. A multi-object tracking method with portion matching is proposed based on 3D segmentation results. The proposed method distills deep feature maps from deep networks, then recognizes and matches object portions using an extended search. Experimental results confirm that the proposed method achieves 2.96% higher on consistent tracking accuracy and 35.48% higher on event identification accuracy than the state-of-art methods. | For the past 25 years NIH Image and ImageJ software have been pioneers as open tools for the analysis of scientific images. We discuss the origins, challenges and solutions of these two programs, and how their history can serve to advise and inform other software projects. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 11,681 |
Control of adsorbates and conduction on CVD-grown diamond surface, using scanning probe microscope | Nanofabrication on a hydrogen-terminated diamond surface is performed by controlling surface adsorbates, using a scanning probe microscope (SPM) technique. Insulated areas are successfully obtained by changing hydrogen termination to oxygen termination. The Auger electron spectrum (AES) indicated the presence of oxygen adsorbed on the modified surface area. A small isolated conductive area is fabricated, and using this structure, a metal–insulator–metal (MIM) diode-like I–V characteristic is observed. Anodic oxidation using the surface water is also suggested for our experimental results. | The XY model with quenched random disorder is studied numerically at T ¼ 0 by a defect scaling method as a model of a disordered superconductor. In 3D we find that, in the absence of screening, a vortex glass phase exists at low T for large disorder in 3D with stiffness exponent h �þ 0:31 and with finite screening and in 2D this phase does not exist. For weak disorder, a superconducting phase exists which we identify as a Bragg glass. In the presence of screened vortex– vortex interactions, the vortex glass does not exist but the Bragg glass does. 2004 Elsevier B.V. All rights reserved. | eng_Latn | 11,682 |
Revealing two-competing processes in carrier dynamics of single-walled carbon nanotube films | Abstract Ultrafast time-resolved optical transmission in single-walled carbon nanotubes was measured as a function of pump fluence at a temperature of 200 K employing degenerate pump–probe experiment. We observed a relaxation dynamics with two components characterized by 0.1 and 1 ps, respectively. The signal amplitude of the slow component also shows a crossover from negative to positive when the pump fluence decreased. It is suggested that the fast component is related to the intraband relaxation and the slow component is attributed to two-competing processes. | Based on geologic features of the West Roadway of Guhanshan Coal Mine, late-model double-deck double-bend space net-crust bracket, which is composed of three-case-bar and three-arch, is designed. After spraying, the loading-carrying structure is formed, and the structure has good plasticity, that is, it can bear great rock pressure. Good support results have been achieved on the spot. | eng_Latn | 11,683 |
The Thermoelectric Properties of PbTe Doped with Na and PbI2 Elements | In this study, the PbTe samples doped with PbI2 or Na were prepared using powder metallurgical techniques. The preparation procedures were optimized by the experimental results with respect to powder particle size, compaction pressure, and influence of sintering parameters. The power factor profiles of the PbTe samples with different dopant concentration at about 100°C to 250°C were calculated from the measured values of the Seebeck coefficient and the electrical of the samples. The research interpretation to the thermoelectric properties had been transformed by means of the different dopant concentration indeed. The power factor of the N-type samples was better than the P-type samples. For optimization of the power factors presented in the measurements temperature range, the optimized dopant concentration of PbI2 is 0.05 at% and of Na is 0.50 at% respectively. | Abstract In recent years, various doping methods for epitaxial graphene have been demonstrated through atom substitution and adsorption. Here we observe by angle-resolved photoemission spectroscopy (ARPES) a coupling-induced Dirac cone renormalization when depositing small amounts of Ti onto epitaxial graphene on SiC. We obtain a remarkably high doping efficiency and a readily tunable carrier velocity simply by changing the amount of deposited Ti. First-principles theoretical calculations show that a strong lateral (non-vertical) orbital coupling leads to an efficient doping of graphene by hybridizing the 2pz orbital of graphene and the 3d orbitals of the Ti adsorbate, which attached on graphene without creating any trap/scattering states. This Ti-induced hybridization is adsorbate-specific and has major consequences for efficient doping as well as applications towards adsorbate-induced modification of carrier transport in graphene. | eng_Latn | 11,684 |
Revealing attractive electron-electron interaction in a quantum dot by full counting statistics | Recent experiments [Nature 521, 196 (2015) and Nat. Commun. 8, 395 (2017)] have presented evidence for electron pairing in a quantum dot beyond the su- perconducting regime. Here, we show that the impact of an attractive electron-electron interaction on the full counting statistics of electron transfer through a quantum dot is qualitatively different from the case of a repulsive interaction. In particular, the sign of higher-order (generalized) factorial cumulants reveals more pronounced correlations, which even survive in the limit of fast spin relaxation. | Abstract In recent years, various doping methods for epitaxial graphene have been demonstrated through atom substitution and adsorption. Here we observe by angle-resolved photoemission spectroscopy (ARPES) a coupling-induced Dirac cone renormalization when depositing small amounts of Ti onto epitaxial graphene on SiC. We obtain a remarkably high doping efficiency and a readily tunable carrier velocity simply by changing the amount of deposited Ti. First-principles theoretical calculations show that a strong lateral (non-vertical) orbital coupling leads to an efficient doping of graphene by hybridizing the 2pz orbital of graphene and the 3d orbitals of the Ti adsorbate, which attached on graphene without creating any trap/scattering states. This Ti-induced hybridization is adsorbate-specific and has major consequences for efficient doping as well as applications towards adsorbate-induced modification of carrier transport in graphene. | eng_Latn | 11,685 |
Interaction of the Important Species HNO and HFSO2 in the Atmosphere: Theoretical Study of the NOH and SOH Blue-Shifted Hydrogen Bonds | Ab initio molecular orbital and density functional theory (dft) in conjunction with different basis sets calculations were performed to study the n-h center dot center dot center dot o and s-h center dot center dot center dot o blue-shifted h-bonds in the hno center dot center dot center dot hfso2 complex. the geometric structures, vibrational frequencies, and interaction energies were calculated by both standard and cp-corrected methods. natural bond orbital (nbo) analysis was used to investigate the origin of blue-shifted h-bonds, showing that the decrease in the sigma*(n-h) and sigma*(s-h) is due to the electron density redistribution effect. the structure reorganization effect on the blue-shifted hydrogen bonds was discussed in detail. (c) 2006 wiley periodicals, inc. | The treatment of graphene oxide (GO) with potassium thioacetate followed by an aqueous work-up yields a new material via the ring-opening of the epoxide groups. The new material is a thiol-functionalized GO (GO-SH) which is able to undergo further functionalization. Reaction with butyl bromide gives another new material, GO-SBu, which shows significantly enhanced thermal stability compared to both GO and GO-SH. The thiol-functionalized GO material showed a high affinity for gold, as demonstrated by the selective deposition of a high density of gold nanoparticles. | eng_Latn | 11,686 |
A novel and simple coplanar waveguide-fed planar monopole antenna for ultra-wideband applications | In this paper, a novel and simple CPW-fed planar monopole antenna is presented for UWB application. The antenna is fabricated on inexpensive FR4 substrate and fed by 50? CPW on the same layer. Measured data show that the antenna provides an impedance bandwidth of about 8GHz for the return loss less than 10dB. It is also observed that the radiation patterns are nearly omni-directional over the entire frequency range. Details of the proposed antenna are presented, and simulated results are presented and discussed. | Abstract We propose a new model which simulates the motion of free electrons in graphene by the evolution of strings on manifolds. In this model, molecules which constitute sheets of graphene are polygonal point-like structures which build ( N + 1 ) -dimensional manifolds. By breaking the gravitational-analogue symmetry of graphene sheets, we show that two separated child sheets and a Chern–Simons bridge are produced giving rise to a wormhole. In this structure, free electrons are transmitted from one child sheet to the other producing superconductivity. An analogue between “effective gravitons” and “Cooper pairs” is found. In principle, this phenomenology provides the possibility to construct superconductor structures by using the analogue of cosmological models. | eng_Latn | 11,687 |
Increased attractive forces between electrodes in an electric discharge | It has been shown that attractive forces exists in an electric discharge that are caused by the discharge itself. The increased attraction between the electrodes of the discharge is ascribed to the charges on the electrodes, and charges of opposite polarity electrons and ions which continuously approach the electrodes. An application of this effect is that of maintaining the discharge. This can overcome the risk of rupture of discharges that occurs in many cases. In a maintained discharge, the springy electrode is so arranged that it will keep it in constant position by the attractive forces originating in the discharge. | The magnetic effects in ferromagnetic graphene basically depend on the principle of exchange interaction when ferromagntism is induced by depositing an insulator layer on graphene. Here we deal with the consequences of non-uniformity in the exchange coupling strength of the ferromagnetic graphene. We discuss how the in- homogeneity in the coordinate and momentum of the exchange vector field can provide interesting results in the conductivity analysis of the ferromagnetic graphene. Our analysis is based on the Kubo formalism of quantum transport. | eng_Latn | 11,688 |
Multiband low profile Modified Inverted-FL strip antenna for 5.2/5.8 GHz WLAN and 5.5 GHz WiMAX applications in laptop computer | This paper contains a multiband low profile Modified Inverted-FL (IFL) strip antenna for 5.2/5.8 GHz WLAN and 5.5 GHz WiMAX operations in a laptop computer. The simulation results are analyzed by means of Numerical Electromagnetic Code-2 (4NEC2) software. This antenna covers −10 dB return loss bandwidth of 900 MHz (5150 MHz ∼6050 MHz). The antenna provides very high peak gains with lower gain variation in its operating bands. The antenna has suitable omnidirectional radiation characteristics. The dimension of the antenna is 16×18.5 mm2, which is very compact in size. So, this low profile antenna is promising to be embedded within the different portable devices employing WiMAX and WLAN applications. | We demonstrate snake-like motion of graphene nanoribbons atop graphene and hexagonal boron nitride (h-BN) substrates using fully atomistic nonequilibrium molecular dynamics simulations. The sliding dynamics of the edge-pulled nanoribbons is found to be determined by the interplay between in-plane ribbon elasticity and interfacial lattice mismatch. This results in an unusual dependence of the friction-force on the ribbon’s length, exhibiting an initial linear rise that levels-off above a junction-dependent threshold value dictated by the pre-slip stress distribution within the slider. As part of this letter, we present the LAMMPS implementation of the registry-dependent interlayer potentials for graphene, h-BN, and their heterojunctions that were used herein, which provides enhanced performance and accuracy. | eng_Latn | 11,689 |
Edge-reflection phase directed plasmonic resonances on graphene nano-structures. | The phase of graphene plasmon upon edge-reflection plays a crucial role on determining the spectral properties of graphene structures. In this article, by using the full-wave simulation, we demonstrate that the mid-infrared graphene plasmons are nearly totally reflected at the boundary together with a phase jump of approximately 0.27π, regardless of the environments surrounding it. Appling this phase pickup, a Fabry-Perot model is formulated that can predict accurately the resonant wavelengths of graphene nano-ribbons. Furthermore, we find that the magnitude of the phase jump will either increase or reduce when two neighboring coplanar graphene sheets couple with each other. This could be used to explain the red-shift of resonant wavelength of periodic ribbon arrays with respect to an isolated ribbon. We provide a straightforward way to uncover the phase jump of graphene plasmons that would be helpful for designing and engineering graphene resonators and waveguides as well as their associated applications. | Abstract We have studied GaAs1−xBix (up to x∼3%) using Raman scattering with two different polarization configurations. Two Bi-induced phonon modes are observed at ∼186 cm−1 and ∼214 cm−1 with increasing Raman intensity as the Bi concentration increases. By comparing Raman selection rules for the observed Bi-induced phonon modes with those for the substitutional N vibrational mode (GaN mode) in GaAsN, the phonon mode at ∼214 cm−1 is identified as originating from substitutional Bi at the As site in GaAsBi. | eng_Latn | 11,690 |
Excellent dielectric properties of Polyvinylidene fluoride composites based on sandwich structured MnO2/graphene nanosheets/MnO2 | Abstract MnO 2 /graphene nanosheets/MnO 2 (MGM) is fabricated by a facile and effective ethanol-assisted graphene-sacrifice reduction method. The morphology and structure of the MGM are examined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The MGM is used as a dielectric filler to prepare MGM/Polyvinylidene composites by solution casting and hot pressing. The MGM/Polyvinylidene composites exhibit excellent dielectric properties (dielectric constant is 2360, dielectric loss is 2.0) near the percolation threshold at 1 kHz which are better than that of most carbon/polymer composites. The excellent dielectric properties originate from the poor conductive MnO 2 layers which not only ensure good dispersion of graphene nanosheets in the Polyvinylidene fluoride but also act as inter-particle barriers to prevent direct contact of the graphene nanosheets. | The diffuse mismatch model (DMM) is one of the most widely implemented models for predicting thermal boundary conductance at interfaces where phonons dominate interfacial thermal transport. In the original presentation of the DMM, the materials comprising the interface were described as Debye solids. Such a treatment, while accurate in the low temperature regime for which the model was originally intended, is less accurate at higher temperatures. Here, the DMM is reformulated such that, in place of Debye dispersion, the materials on either side of the interface are described by an isotropic dispersion obtained from exact phonon dispersion diagrams in the [100] crystallographic direction. This reformulated model is applied to three interfaces of interest: Cr–Si, Cu–Ge, and Ge–Si. It is found that Debye dispersion leads to substantially higher predictions of thermal boundary conductance. Additionally, it is shown that optical phonons play a significant role in interfacial thermal transport, a notion not pre... | eng_Latn | 11,691 |
Electrochemical Mechanism for Fullerene Formation in Plasma Arcs | During the synthesis of fullerenes by dc plasma arcs, it has been found that the anodic graphite rod consistently burns up, while the cathodic graphite rod grows slag at its end. Further investigations revealed that the anodic and cathodic graphite rods p | Abstract Thanks to their high hydrogen permeability, vanadium based alloys can be a valuable and sustainable alternative to palladium alloys, commonly employed in commercial membranes for hydrogen purification/separation. In this work, the unprecedented deposition of micrometric vanadium-based multilayers and their investigation as hydrogen selective membranes have been reported. In particular, this work describes the use of High Power Impulse Magnetron Sputtering, a technique easily scalable also for complex geometries, for the deposition of dense and crystalline Pd/V93Pd7/Pd multilayers with total thickness | eng_Latn | 11,692 |
Origin of metazoan adhesion molecules and adhesion receptors as deduced from cDNA analyses in the marine sponge Geodia cydonium: a review | The phylogenetic relationships of the kingdom Animalia (Metazoa) have long been questioned. Whether the lowest eukaryotic multicellular organisms, the metazoan phylum Porifera (sponges), independently evolved multicellularity from a separate protist lineage (polyphyly of animals) or whether they were derived from the same protist group as the other animal phyla (monophyly) remains unclear. Analyses of the genes that are typical for multicellularity, e.g. those coding for adhesion molecules (galectin) and adhesion receptors (receptor tyrosine kinase, integrin receptor, receptors featuring scavenger receptor cysteine-rich domains) or elements involved in signal transduction pathways (G-proteins, Ser/Thr protein kinases), especially from the marine sponge Geodia cydonium, indicate that all animals, including sponges, are of monophyletic origin. | The results of the theoretical investigation of the curvature influence of the strained graphene nanoribbon on its sensory ::: properties are presented in the given work. The attachment mechanisms of hydrogen atoms to the plane and the wavelike ::: graphene nanoribbon are studied by the tight-binding method. For the first time it was established, that the sensory ::: properties of nanoribbon improve with increase of the surface curvature. It was revealed, that the potential well depth of ::: interaction of the curved graphene with hydrogen atom is greater than the planar graphene. It was established, that the ::: difference of the potential minima of the C-H interaction energy increases exponentially with the curvature increase. | eng_Latn | 11,693 |
Electron Screening in 7Be + p --> 8B + photon reaction | We evaluate the effect of screening by bound electron in (7Be,e) + p --> (8B,e) + photon transition in the framework of the adiabatic representation of the three particle problem. Comparison with two approaches (united nucleus and static) is presented. We discuss possible applications of this effect both for Solar Neutrinos and low energy fusion experiments. | Abstract The possibilities of diamond-like carbon film applications for protection and stabilization of selenium-containing photoreceptors in electrophotography have been studied experimentally. We have determined the optimal conditions for deposition of diamond-like a-C:H films as well as their thickness at which the electrophotographic characteristics and the printing quality are not deteriorated as compared with control samples of a-Se. The effect of amorphous phase stabilization in the selenium photoreceptors when depositing the a-C:H layer has been revealed. The service life of copying cylinders with a protective a-C:H coating increases by a factor of 2–3. | eng_Latn | 11,694 |
Patterning monolayer graphene with zigzag edges on hexagonal boron nitride by anisotropic etching | Graphene nanostructures are potential building blocks for nanoelectronic and spintronic devices. However, the production of monolayer graphene nanostructures with well-defined zigzag edges remains a challenge. In this paper, we report the patterning of monolayer graphene nanostructures with zigzag edges on hexagonal boron nitride (h-BN) substrates by an anisotropic etching technique. We found that hydrogen plasma etching of monolayer graphene on h-BN is highly anisotropic due to the inert and ultra-flat nature of the h-BN surface, resulting in zigzag edge formation. The as-fabricated zigzag-edged monolayer graphene nanoribbons (Z-GNRs) with widths below 30 nm show high carrier mobility and width-dependent energy gaps at liquid helium temperature. These high quality Z-GNRs are thus ideal structures for exploring their valleytronic or spintronic properties. | Genetic simulated annealing algorithm coupled with niche is applied to search rock slope's critical slip surface in this study.Based on the slope structural plane simulation,the genetic simulated annealing algorithm coupled with niche can search the critical slip composed of the joints and rock-bridges.Compared with other intelligent algorithms,it has the merit of faster convergence rates and can find all extremes in a short time without strict requests for parameters. | eng_Latn | 11,695 |
Single electron tunneling as a possible conduction mechanism in diamond like carbon film | Nonlinear current voltage characteristics and in some cases also step like characteristics were observed in diamond like carbon films. We suggest that the transport mechanism is tunneling between conducting nanoparticles in the films and the observation of step like structures is a manifestation of Coulomb blockade found for the first time in these films. We point out that the origin of similar current voltage characteristics observed in other carbon structures can be also Coulomb blockade phenomenon. | We examine the influence of Ni impurity in cuprates on the distribution of hole carriers by performing numerically exact diagonalization calculations for a model consisting of $\text{Cu}\text{ }3d$, $\text{Ni}\text{ }3d$, and $\text{O}\text{ }2p$ orbitals. Using realistic parameters for the system, we find that a hole is predominantly bound to $\text{O}\text{ }2p$ orbitals around the Ni impurity forming the Zhang-Rice doublet. This imposes strong restrictions on modeling Ni-substituted cuprates. We propose a resonant inelastic x-ray scattering experiment for $\text{Ni}\text{ }K$ edge to confirm hole binding around the Ni impurity. | eng_Latn | 11,696 |
Structural ordering of diamond like carbon films by applied electric field | Diamond like carbon films deposited by RF magnetron sputter deposition technique contain both SP2 and SP3 hybridized carbons. These films are structurally disordered and inhomogeneous. By the application of electric field across the film, these films are transformed to a more orderly structured diamond like carbon, bringing homogenity in the film. This transformation has resulted in the increase of the reflectivity of the metal(Aluminum), which is used as one of the electrodes for applying the electric field, by 5 times. | A recently presented dynamic model concerning the electronically induced crystallographic transition is solved rigorously with higher-order terms in the distortion operator also taken into account. | eng_Latn | 11,697 |
Dual Counterion Systems of Carboxylated Nanocellulose Films with Tunable Mechanical, Hydrophilic, and Gas-Barrier Properties | Aqueous dispersions of C6-carboxylated cellulose nanofibrils with sodium counterions (CNF-COONa) and CNFs with tetraethylammonium counterions (CNF-COONEt4) were mixed at various weight ratios. Transparent, flexible CNF-COONa/NEt4 films were prepared by casting and drying aqueous mixtures with various Na/NEt4 molar ratios as dual counterion systems. The film density, Young’s modulus, and tensile strength decreased linearly with increasing molar ratio of the bulky NEt4 counterion. The film hydrophilicity was controlled by varying the Na/NEt4 molar ratio. The oxygen and water vapor permeabilities also increased with increasing molar ratio of bulky NEt4 counterions. The mechanical, hydrophilic, and gas-barrier properties were tuned by controlling the Na/NEt4 molar ratios of CNF films containing dual counterions. The results of model experiments using tetra(n-butyl)ammonium hydroxide indicated that the Na and quaternary alkylammonium counterions were homogeneously distributed among the carboxylated CNF element... | Abstract This research is focused on the effects of nonlinear terms on the dynamical behavior of graphene reinforced laminated composite plates. Firstly, the governing equations of the graphene reinforced composite thin plate subjected to transverse excitations are derived by using the Hamilton's principle and the von Karman deformation theory. Then numerical method is applied to investigate the nonlinear behaviors of graphene reinforced composite plates. Bifurcation diagram, waveform and phase portrait are demonstrated to analyze the nonlinear dynamics of the graphene reinforced laminated composite plates. Furthermore, the effects of nonlinear terms on the dynamical behavior are discussed in detail, where both the stronger and weaker nonlinear characteristics of lower modes of the plate are presented. Moreover, some interesting phenomena are obtained in numerical simulation. | eng_Latn | 11,698 |
Interpretation of dynamical diffuse scattering of fast electrons in rutile | An Einstein model for thermal diffuse scattering is extended to a fully dynamical n-beam Bloch-wave treatment, where explicit account is taken of the scattering site symmetry from individual atoms. Dynamical effects in this model are related to orientation-dependent fluctuations in current density on localized scattering centres within the crystal, yielding excess or deficit Kikuchi bands. Calculated diffuse scattering distributions are compared with experimental observations from rutile (TiO2). The predicted diffuse distribution for scattering from oxygen sites correlates reasonably well with experiment, implying a relatively weak contribution for (localized) thermal diffuse scattering of fast electrons from titanium sites. | We present the design for the chalcogenide nanofiber coated with a thin finite tellurite cladding. The effects of the thickness of the tellurite coating on the dispersion and the nonlinearity of the nanofiber are studied. | eng_Latn | 11,699 |
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