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Parity-Controlled Self-Assembly of Supramolecular Helices in a Gold(I)–Copper(II) Coordination System with Penicillamine and Bis(diphenylphosphino)alkane
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A unique gold(I)–copper(II) 1D polymeric system, [Cu{Au2(LCn)(pen)2}] (LCn = Ph2P(CH2)nPPh2 (n = 3, 4, and 5); H2pen: penicillamine), which involves three types of helices (single-stranded homochir...
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We propose a pilot-based coding (PBC) scheme for lossless bit rate reduction of parametric stereo (PS) in enhanced aacPlus. It uses PBC in addition to the existing frequency and time differential coding to encode and decode PS parameter indexes. We also design optimal Huffman codebooks (HCBs) for PBC in the proposed scheme. Experiments show that the proposed scheme is superior to the original coding scheme, where both the new coding structure and the optimal HCBs contribute to the bit rate reduction.
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eng_Latn
| 31,600 |
Metal triflates and tetrafluoroborates as water-tolerant Lewis acids for cationic polymerization in aqueous media
|
Metal triflates or tetrafluoroborates, such as Zn(OTf)2, Cu(OTf)2, Sn(OTf)2, and Zn(BF4)2 (OTf = −OSO2CF3), were employed as water-tolerant Lewis acids for the emulsion cationic polymerization of p-methoxystyrene (pMOS) in heterogeneous aqueous media. All these metal compounds, in addition to rare earth metal triflates such as Yb(OTf)3 already reported by us, induced the polymerization of pMOS in conjunction with the pMOS−HCl adduct (1) (initiator) and dodecyltrimethylammonium chloride (surfactant) at 30 °C in water. The pMOS polymerization was controlled, where the molecular weights of the polymer increased with monomer conversion and the molecular weight distributions were relatively narrow (Mw/Mn ∼ 1.4). 1H NMR analysis of the obtained polymers showed that the chlorine atom originating from 1 was attached to the growing polymer terminal. In addition, the water tolerance of these catalysts was confirmed by 19F NMR analysis. Thus, the emulsion cationic polymerization proceeds via reversible activation of...
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A fluorometric enzyme assay was developed to evaluate the ability of a variety of compounds to bind to and/or inhibit pyroglutamyl aminopeptidase I. Among these compounds were a series of chloromethyl ketone analogues of thyrotropin releasing hormone (TRH) which had previously been shown to possess TRH-like activity in the central nervous system and have now been found to be good inhibitors of pyroglutamyl aminopeptidase. Thus, it is suggested that the observed TRH-like CNS activity could derive indirectly from inhibition of endogenous TRH degradation by pyroglutamyl aminopeptidase I.
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eng_Latn
| 31,601 |
Study of the thermo-oxidative stability and antioxidant effectiveness of bisphenols of different structure
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The thermo-oxidative stability and antioxidant effectiveness of bisphenols obtained by the condensation of 2-tert-butyl-4-methylphenol with C 1 -C 5 aldehydes of aliphatic series have been studied for the first time. It has been established that these features of synthesized bisphenols depend on the structure of the hydrocarbon bridge between the phenyl groups, and their oxidation proceeds according to the laws governing the process of liquid-phase oxidation. It has been shown that the degradation of the investigated series of bisphenols is described by a kinetic equation with an order of the reaction of 1.25n and E a = 74.4 kJ/mole.
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The size effect on thermal conductivity of free standing wires with square cross-section is investigated. The thermal conductivity is calculated using the Boltzmann transport equation (BTE). A simple expression for the reduction in conductivity due to the increase of boundary scattering is presented. The thermal conductivity of the wires is found to decrease rapidly below the bulk values. This decrease in square wires is smaller than that which occurs in a film with out-of-plane heat flux. The values of thermal conductivities deduced from our calculation agree well with the experimental data of sodium wires.
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eng_Latn
| 31,602 |
Inhibitor protection of steels in acid and neutral media by the derivatives of 2-mercaptobenzimidazole
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We study the anticorrosion properties of newly synthesized derivatives of 2-mercaptobenzimidazole and the efficiency of their action in compositions based on the wastes of production of ɛ-caprolactam at the Chernihiv “Khimvolokno” Open Joint-Stock Company. A conclusion is made that these compounds can be used as corrosion inhibitors for 20 steel placed in acid and neutral media. The efficiency of application of protective compositions based on the wastes of production of ɛ-caprolactam with admixtures of the derivatives of 2-mercaptobenzimidazole is demonstrated for working media with pH 1–6.5.
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Abstract Asymmetric total synthesis of small ring macrolide stagonolide-E has been described in this communication. The main highlight of our synthetic strategy is the application of ME-DKR (metal enzyme combo dynamic kinetic resolution) reaction, asymmetric reduction with Noyori’s BINAL-H reagent system, stereoselective cross metathesis, and RCM (ring closing metathesis) reaction at a late stage enables us to achieve the synthesis of the target molecule in an efficient way.
|
eng_Latn
| 31,603 |
Synthesis of chiral γ -sultams through intramolecular reductive amination with sulfonylcarbamate as N- source
|
Abstract An efficient and enantioselective palladium-catalyzed intramolecular asymmetric reductive amination with sulfonylcarbamates as N -sources was reported, providing a facile and general access to the chiral γ -sultam derivatives with up to 97% of enantioselectivity. This tandem process avoids additional deprotection manipulation and arduous isolation of the N -sulfonyl-imine intermediates.
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Organic contamination adsorbed on 200 mm silicon wafers was characterized using various analytical techniques. Surface hydrophobicity, apparent optical thickness and electrical surface charge are used to characterize the silicon surface state. They only give information on total organic contamination. MIR-FTIR is very sensitive for detecting CH2 and CH3 contained in organics on silicon wafers. TOF-SIMS is quite sensitive and enables some of the organics to be recognized by identifying the molecule fragments. TDGC-MS is the most relevant technique to identify organic contamination on silicon wafers as extensive identification libraries exist.
|
eng_Latn
| 31,604 |
Effect of σ,π conjugation on199Hg chemical shifts
|
The199Hg NMR spectra of compounds of the type HgCC=C and HgCC=0 have been studied and it has been shown that C-Hg/ π conjugation produces a sharp increase in the shielding of the mercury nucleus.
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A variety of push–pull type organic dyes are facilely synthesized through the most atom-economical C–H/C–H dehydrogenative coupling reactions. After comprehensive synthetic optimizations, a broad substrate scope is achieved and functional groups, such as ester, ketone, nitrile, nitro, and triazene are well tolerated. The sensitive aldehyde group required for the conversion into anchoring groups for DSSCs applications is also compatible under present oxidant-containing reaction conditions. Based on this optimum C–H/C–H coupling approach, three new organic sensitizers are readily prepared and submitted to solar cell device fabrications, giving the power conversion efficiency (PCE) up to 4.85%. This work constitutes the first example that connects high atom-efficiency C–H/C–H green catalysis with dye-sensitized solar cell applications.
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eng_Latn
| 31,605 |
Hydroxy-Substituted Polycyclic Aromatic Hydrocarbon Ions as Sources of CO and HCO in the Interstellar Medium
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Tandem mass spectrometry was used to explore the trends in the unimolecular fragmentation of the ionized hydroxy-substituted polycyclic aromatic hydrocarbons 1-naphthol, 9-hydroxyphenanthrene and 1-hydroxypyrene. The main dissociation reactions across all ring systems were CO- and HCO-loss, with ionized 1-naphthol also losing H atoms. Both ionized 1-naphthol and 9-hydroxyphenanthrene displayed the sequential loss of C2H2 and C4H2 from the [M-HCO]+ ions, reminiscent of unsubstituted PAH ions. CO-loss is slightly favored for 1-naphthol and 9-hydroxyphenanthrene at low collision energy, but less so for 1-hydroxypyrene. Reaction mechanisms for HCO- and CO-losses from 1-hydroxypyrene were derived from CCSD/6-31G(d)//B3-LYP/6-31G(d) calculations. The CO-loss mechanism is dominated by two transition states, TS-A governing a 1,3-H shift in the molecular ion, and TS-C which governs a ring-closing step to form a five-member ring in the product ion. HCO-loss occurs over a much flatter potential energy surface with t...
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In search of protective antigens which can be used in a vaccine to prevent Helicobacter pylori infection, we report on the identification of four genes, hopV, hopW, hopX and hopY, and the characterization of the corresponding proteins which belong to the H. pylori outer membrane protein (Hop) family containing 32 homologous members, some of which were shown to function as porins. Sequence analysis of 16 different H. pylori strains revealed that the proteins HopV, HopW, HopX and HopY are highly conserved. Localization of HopV, HopW, HopX and HopY at the surface of the bacteria was investigated by immunofluorescence. Using a planar lipid bilayer system the proteins HopV and HopX were shown to form pores with single-channel conductances of 1.4 and 3.0 nS, respectively.
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eng_Latn
| 31,606 |
New variation on a theme: structure and mechanism of action of hydrolytic antibody 7F11, an aspartate rich relation of catalytic antibodies 17E8 and 29G11
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Abstract A computer model, based on homology, of the catalytic antibody 7F11 that catalyses the decomposition of the benzoate ester of a dioxetane resulting in chemiluminescence is reported. Antibody 7F11 has 89% identity in the V L domain, and 72% identity in the V H domain with hydrolytic antibodies 17E8 and 29G11 previously reported by Scanlan et al. These were also raised against a phosphonate containing hapten. The antigen-binding site of antibody 7F11 whilst similar to that of 17E8 has aspartic acids at positions 33H and 35H, reminiscent in position of the catalytic residues found in aspartate proteinases such as pepsin. AutoDock 3.0 has been used to identify the best binding mode for the hapten. Molecular dynamic simulations have also been undertaken to examine any major conformational changes induced by hapten binding. A mechanism for benzoate ester hydrolysis involving the aspartic acid side-chains is proposed. Construction of a single-chain variable fragment (scFv) of 7F11 is also reported.
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4 analogs of naturally occurring gallotannins have been synthesized upon acylation of sucrose by 2, 3, 6 and 8 galloyl groups. In a simple test using the DPPH radical, the antioxidant activity of such esters appears proportional to the number of the galloyl units. ::: ::: Sucrose derivatives bearing 2, 3, 6 and 8 galloyl groups have been synthesized and tested for antioxidant activity. ::: Download full-size image
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eng_Latn
| 31,607 |
Synthesis and biological evaluation of 2-(4-methylsulfonyl phenyl) indole derivatives: multi-target compounds with dual antimicrobial and anti-inflammatory activities
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Three series of 2-(4-methylsulfonylphenyl) indole derivatives have been designed and synthesized. The synthesized compounds were assessed for their antimicrobial, COX inhibitory and anti-inflammatory activities. Compound 7g was identified to be the most potent antibacterial candidate against strains of MRSA, E. coli, K. pneumoniae, P. aeruginosa, and A. baumannii, respectively, with safe therapeutic dose. Compounds 7a–k, 8a–c, and 9a–c showed good anti-inflammatory activity with excessive selectivity towards COX-2 in comparison with reference drugs indomethacin and celecoxib. Compounds 9a–c were found to release moderate amounts of NO to decrease the side effects associated with selective COX-2 inhibitors. A molecular modeling study for compounds 7b, 7h, and 7i into COX-2 active site was correlated with the results of in vitro COX-2 inhibition assays.
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Abstract Heparin and dextran sulphate (DS) enhanced the thrombin/antithrombin III (AT III) reaction by stoichiometric binding to the enzyme in the absence of chloride ions. This binding and the tight association of heparin with the trhombin residue in its complex with AT III was demonstrated by a gel permeation chromatographic technique. Since the catalytic ability of heparin was superior to that of DS, loose association of the sulphated polysaccharides with thrombin was essential for their catalytic action.
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eng_Latn
| 31,608 |
An effective scalar magnetic interaction for resonantly trapped atoms
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Atoms can be trapped using a combination of static and rotating magnetic fields. A theoretical analysis is performed of a rotating polarization axis that is used to eliminate regions of zero coupling. A similar result is found using linear polarization, but in the case of circular polarization no orientational dependence in the coupling remains when on resonance.
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Using the ADAPT and CHEMLAB-II systems for structure-activity analysis, computer-calculated electronic properties of molecules were used to derive structure-activity relationships for predicting the mutagenicity of a set of substituted acridines in strain TA1537 of the Ames Salmonella assay. A collection of 40 acridines, with a variety of substituents, was examined. A set of 4 electronic descriptors was found which could be used to correctly classify all but two of the compounds as mutagenic or nonmutagenic. A negative correlation was found between the sum of the Hammett aromatic substituent parameters and the level of mutagenicity of the structures, expressed as log(number of revertants/plate + 1) at a 20-micrograms dose. This correlation, however, was not high enough to allow precise estimation of the mutagenicity values.
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eng_Latn
| 31,609 |
Preparation and characterization of Phthalocyanine Blue encapsulated with silane coupling agent for blue light curable inkjet printing of textiles
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Abstract A novel reactive organic pigment complex was prepared by 3-(Trimethoxysilyl) propyl methacrylate encapsulated on the surface of the organic pigment. The preparation conditions of the reactive organic pigment complex were optimized and the properties were characterized by FT-IR, DLS and UV–vis. The reactive organic pigment complex was used in blue-light curable pigment inks. The results showed that the photo-polymerization performance of the novel blue light curable pigment ink system was markedly increased in comparison with conventional pigment-based ink systems. The physical shielding effect of pigment particles on photo-polymerization performance can be reduced by increasing the photoinitiator concentration and irradiation intensities. The colorfastness to crocking of printed fabric was remarkably improved. However, the particle size of reactive organic pigment complex was slightly increased.
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From a physiological point of view, a close correlation has been suggested between the induction of embryogenesis, i.e. morphological differentiation, and that of anthocyanln synthesis, i.e. metabolic differentiation. I established a carrot suspension culture system in which anthocyanin synthesis and embryogenesis could be induced in the same culture and studled their relations. The results suggested that induction of anthocyanin and that of cell division, or undifferentiated growth, were the alter natures regulated by 2, 4-dichlorophenoxyacetic acid (2, 4-D). The activities of phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) were found to play key roles in the regulation of anthocyanin synthesis by 2, 4-D. PAL and CHS genes and their transcripts were analyzed in detail, which indicated that there are two PAL genes in carrot, one being transiently and rapidly activated by stress, and the other being specifically induced during the 2, 4-D regulated anthocyanin synthesis.
|
eng_Latn
| 31,610 |
Structures of 1,4,13,16-Tetraoxa-7,10-dithia[16](1,1′)ruthenocenophane and Its 1:2 HgCl2Complex
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The reaction of 1,1′-bis(6-chloro-1,4-dioxahexyl)ruthenocene with disodium 1,2-ethanedithiolate gave 1,4,13,16-tetraoxa-7,9-dithia[16](1,1′)ruthenocenophane (5) in 63% yield. The reaction of 5 with HgCl2 in acetonitrile gave a 1: 2 complex (6) in 47% yield. The crystal structure of complex 6 and its metal free ligand 5 were determined by an X-ray method. Crystal data: 5, triclinic, a=11.128(2), b=12.720(2), c=10.196(2)A, α=113.55(1), β=64.13(1), γ=122.01(1)°, U=1074.1 A3. P\bar1, Z=2, Dc=1.54 Mg m−3, μ(Mo Kα)=9 mm−1. R=0.028. 6, triclinic, a=16.595(4), b=12.645(3), c=7.401(1)A, α=104.92(1), β=92.37(1), γ=69.38(2)°, U=1402.4A3, P\bar1, Z=2, Dc=2.46 Mg m−3, μ(Mo Kα)=12.2 mm−1, R=0.081. The X-ray analysis of 6 revealed that one Hg atom was bonded to the Ru atom of the ruthenocene nucleus with a distorted trigonal-planar configuration and another Hg atom was bonded to the two sulfur atoms of the macrocycle. This result is completely different from that obtained regarding complex 4,7,10,13-tetraoxa-1,16-dithia...
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A double-blind randomized study of ten patients compared Hexabrix 32% to Renografin-60 in TMJ arthrography. Equivalent volumes of contrast material were injected under fluoroscopic observation, with film quality and patient subjective response graded independently by three radiologists. In immediate arthrogram quality, Hexabrix was rated excellent; Renografin-60 was rated good. For 10-minute radiographs, Hexabrix had a good to excellent rating; Renografin-60 rated fair to good in image quality. Significantly less pain was experienced with Hexabrix.
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eng_Latn
| 31,611 |
Photochemistry of the o-nitrobenzyl system in solution: effects of distance and geometrical constraint on the hydrogen transfer mechanism in the excited state
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Two rigid nitrobenzene derivatives, 5-nitro-1,2,3,4-tetrahydro-1,4-methanonaphthalene (6), and 5-nitro-1,2,3,4-tetra-hydro-1,4-ethanonaphthalene (7), have been synthesized and studied by picosecond flash absorption spectroscopy, steady-state irradiation, and MMX molecular mechanics calculations. Transients with lifetimes of 770 and 410 ps have been detected and assigned to the excited triplet states of 6 and 7, respectively. Consistent with prediction, the o-quinonoid intermediate is not detected in the time domain between the laser excitation and the end of decay of the triplet state. Intramolecular abstraction of the bridgehead benzylic hydrogen by the cited triplet state proceeds with relative rates of 1:125 for 6 and 7, respectively. Since structural constraints prohibit the formation of an orthoquinonoid intermediate in these systems, formation of the usual nitrosoalcohol 13 represents the first substantiation of the biradical route to product (3′ → 4, Scheme 1). Absorption of the intermediate triple...
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Development of methods of pollution prevention is a strategic orientation for environmental protection. This paper describes studies on waste minimization in benzaldehyde production by using indirect electrochemical oxidation of toluene instead of the seriously polluting traditional chemical process. The new technology developed eliminates the discharge of wastewater by recycling the reactive solution and gives a higher yield of benzaldehyde.
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eng_Latn
| 31,612 |
Presence of a histidine at the active site of the neutral endopeptidase-24.11.
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Diethylpyrocarbonate treatment of the neutral endopeptidase (EC 3.4.24.11) inhibits both catalytic activity and binding of the inhibitor [3H]-N(R,S)-3-hydroxyaminocarbonyl-2-benzyl-1-oxopropyl]-glycine. The loss of activity can be reversed by hydroxylamine and almost completely prevented by the competitive inhibitor phenylalanyl-leucine suggesting the presence, as in thermolysin, of a histidine residue at the active site. Butanedione treatment also reduces both catalytic activity and [3H] inhibitor binding. Phenylalanyl-leucine completely protects from the butanedione induced loss of activity, providing further evidence for an essential arginine at the active site. In contrast, the tyrosine modifying agent N-acetylimidazole has no apparent effect on enzyme activity.
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In this letter, we report the singlet ground state structure of the full carotenoid peridinin by means of variational Monte Carlo (VMC) calculations. The VMC relaxed geometry has an average bond length alternation of 0.1165(10) Å, larger than the values obtained by DFT (PBE, B3LYP, and CAM-B3LYP) and shorter than that calculated at the Hartree-Fock (HF) level. TDDFT and EOM-CCSD calculations on a reduced peridinin model confirm the HOMO-LUMO major contribution of the Bu(+)-like (S2) bright excited state. Many Body Green's Function Theory (MBGFT) calculations of the vertical excitation energy of the Bu(+)-like state for the VMC structure (VMC/MBGFT) provide an excitation energy of 2.62 eV, in agreement with experimental results in n-hexane (2.72 eV). The dependence of the excitation energy on the bond length alternation in the MBGFT and TDDFT calculations with different functionals is discussed.
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eng_Latn
| 31,613 |
(2Z,3Z)-Quinoxaline-2,3(1H,4H)-dione dioxime
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The asymmetric unit of the title compound, C8H8N4O2, contains one half-molecule; a twofold rotation axis bisects the molecule. An intramolecular N—H⋯O hydrogen bond results in the formation of a five-membered ring, which displays an envelope conformation. In the crystal structure, intermolecular O—H⋯N hydrogen bonds link the molecules.
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In this paper, we reviewed the degradation factors of diazinon which was known to be easily degraded by soil microorganisms and lost of its activity. Under submerged soil condition, the contribution of microorganisms to diazinon degradation was about 40% and these microorganisms preferred soil humus as substrates to diazinon itself. The effect of monooxygenase activity in submerged soil was more important than esterase activity on diazinon degradation and these enzymes were inhibited by several chemicals such as piperonyl butoxide(PBO), EPN and tricyclazole. From these results, new formulation type of diazinon (PBO and triphenyl phosphate were added to commercial diazinon formulation by 0.1% respectively.) and diazinon mixture formulation (diazinon was mixed with EPN, tricyclazole and carbofuran in equal amount) were prepared. The new formulation type of diazinon showed better insecticidal activity by 12% and more delayed diazinon degradation in ten days than commercial diazinon.
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hrv_Latn
| 31,614 |
43Ca NMR studies of Ca2+-Tetrahymena calmodulin complexes
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43Ca NMR spectra of Ca2+-Tetrahymena calmodulin(Tet. CaM.) complexes have been observed under various conditions. Off-rate of Ca2+ from Tet. CaM. is estimated to be approx. 2.7 × 103 s−1 under a certain assumption. Relaxation rates of 43Ca NMR of Ca2+-Tet. CaM. are remarkably increased(by one order in magnitude) by adding trifluoperazine(TFP), a potent calmodulin antagonist. Relaxation parameters estimated suggest that Ca2+ mobility is reduced by the TFP binding. A stoichiometry of TFP is two moles per Tet. CaM. molecule. The relaxation rates of 43Ca NMR signals are increased by adding excessive Mg2+ to the Ca2+-Tet. CaM. solutions. The addition of Mg2+ to the Ca2+-Tet. CaM. complex decreases apparent pKa value of the complex as well.
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Abstract A low frequency noise and charge carrier transport mechanisms were investigated on tantalum capacitors made by various producers. The model of Ta–Ta 2 O 5 –MnO 2 MIS structure was used to give physical interpretation of I – V characteristics in normal and reverse modes. The noise in time and frequency domain was examined and noise sources were identified. We evaluated correlation between leakage current and noise spectral density and discussed corresponding quality and reliability indicators.
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eng_Latn
| 31,615 |
Discovery of benzophosphadiazine drug candidate IDX375: A novel hepatitis C allosteric NS5B RdRp inhibitor.
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Abstract Hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase (RdRp) plays a central role in virus replication. NS5B has no functional equivalent in mammalian cells, and as a consequence is an attractive target for selective inhibition. This paper describes the discovery of a novel family of HCV NS5B non-nucleoside inhibitors inspired by the bioisosterism between sulfonamide and phosphonamide. Systematic structural optimization in this new series led to the identification of IDX375, a potent non-nucleoside inhibitor that is selective for genotypes 1a and 1b. The structure and binding domain of IDX375 were confirmed by X-ray co-crystalisation study.
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Abstract The mechanisms for the insertion of alkylidenecarbenes into O H bond of water have been investigated with B3LYP/6-311G(d,p) method. The XYC C + H 2 O (XYC C: H 2 C C, HFC C, HClC C, HBrC C, H(CH 3 )C C, F 2 C C, Cl 2 C C, Br 2 C C, (CH 3 ) 2 C C) system is the subject of the present study. According to our model calculations these insertion reactions can yield vinyl alcohol products and for a given single substituted alkylidenecarbene will yield cis–trans -isomer mixtures. Moreover the reactivity of alkylidenecarbene decreases in the order: HFC C > HClC C > HBrC C > H(CH 3 )C C > H 2 C C. The same phenomenon can be found in double substituted alkylidenecarbene, that is, F 2 C C > Cl 2 C C > Br 2 C C > (CH 3 ) 2 C C > H 2 C C. Our theoretical findings suggest that the singlet–triplet splitting (Δ E ST ) of the XYC C species can be used as a guide to predict its activity for insertion reactions.
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eng_Latn
| 31,616 |
Effects of alkali-heat treatment on β-melanocyte-stimulating hormone
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Abstract Prolongation of the activity of β-melanocyte-stimulating hormone is produced by heating in 0.1 N NaOH at 100 °C. for 10 minutes. Zone electrophoresis on starch and countercurrent distribution have been employed to demonstrate the multiplicity of the products formed. Chemical and microbiological amino acid analyses of the major product(s) resolved by electrophoresis indicate that the following has taken place: ( 1 ) conversion of arginine to ornithine; ( 2 ) cleavage of a gly.ser. peptide bond with loss of the C-terminal pentapeptide ser.pro.pro.lys.asp; and ( 3 ) extensive racemization of arginine, histidine, methionine, and phenylalanine. Consideration of these findings and those obtained with other melanocyte-stimulating hormones and synthetic peptides, indicates that racemization alone is sufficient to explain the prolongation phenomenon.
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Various condensation products were obtained by the reaction between pyruvic acid and urea. They are 5-hydroxy-5-methyl-hydantoin, homoallantoin, homoallantoic acid, and dipyruvic triureide. 5-Methylene-hydantoin was prepared from some of these compounds, or directly from pyruvic acid and urea, by reactions in organic acid. The most convenient method was the dehydration of 5-hydroxy-5-methyl-hydantoin, which is a new compound melting at 166°C. 5-Methylene-hydantoin, m. p. 214°C, is a new monomer of the vinylidene type which polymerizes easily by means of a free radical mechanism. 3-Methyl-5-methylene-hydantoin was also prepared from 5-hydroxy-5-methyl-hydantoin through its 3-methyl derivative.
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eng_Latn
| 31,617 |
Persistent Radical Pairs Between N‐Substituted Naphthalimide and Carbanion Exhibit pKa‐Dependent UV‐vis Absorption
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A new strategy is devised for estimating and screening pK a values among different carbon acids under ambient conditions via the UV-vis absorption spectrum of persistent radical pairs (PRPs), which are generated from an N -substituted naphthalimide (NNI) derivative in the presence of various carbanions in organic solutions. The electron paramagnetic resonance (EPR) spectroscopy is used to examine the presence of radicals. Unexpectedly, it was discovered that the UV-vis spectrum of PRPs reveals a distinct linear relationship between the PRP absorption and the pK a value of a corresponding carbon acid, which is likely due to the energy difference among different RPRs. The finding may offer organic chemists an alternative reference to conduct carbanion-mediated reactions in various organic solutions.
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The formula for correction for reabsorption in the case of a plane-parallel luminophor excited and observed from one side is presented in a form convenient for computation. This form clearly shows the effect on the reabsorption correction of changing the parameters of the experiment.
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eng_Latn
| 31,618 |
New NMR evidence on the uranylcitrate complexes
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Abstract A 1 H and 13 C NMR study of the complexation of citric acid to uranyl ion is reported over a wide pH range (1.3–10.3). At least six complexes are formed. Structures are proposed for four of them; in particular one of the complexes dominant at high pH values seems to be a cyclic trimer (3:2).
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Abstract A novel protecting group for the 2′-hydroxyl of ribonucleosides, p -nitrobenzyloxymethyl, is used in the rapid solid phase synthesis of the oligonucleotide U(U) 11 U; it can be readily removed from the oligomer product by treatment with tetrabutylammonium fluoride.
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eng_Latn
| 31,619 |
58-82 GHz 4: 1 dynamic frequency divider using 100 nm metamorphic enhancement HEMT technology
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The design and performance of a dynamic divider by four based on a 100 nm metamorphic enhancement HEMT technology operating in the range 58 to 82 GHz is presented. To the knowledge of the authors, this is the highest operation frequency obtained for a dynamic divider based on HEMT technology. The complete circuit has a power consumption of approximately 500 mW for a supply voltage of -3.5 V The input signal is single-ended. The output driver is able to drive a 50 /spl Omega/ external load.
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Abstract Octasubstituted phthalocyanine derivatives have been synthesized and characterized. The mesophases were studied by optical microscopy, differential scanning calorimetry and small angle X-ray diffraction. For the 2-ethyl-hexyloxy-derivative, three transitions are observed at 170°C, 223°C and 270°C. In the latter temperature range, X-ray diffraction indicates the presence of a nematic phase which shows homeotropic orientation on untreated surfaces of a glass slide.
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eng_Latn
| 31,620 |
Analysis of Chlorinated Paraffins in Environmental Matrices: The Ultimate Challenge for the Analytical Chemist
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Commercial chlorinated paraffins (CPs) are derived from the free radical chlorination of n-alkane mixtures. Starting mixtures used in the synthesis fall into three categories: C10–C13 (short); C14–C17 (medium) and C20–C30 (long). This results in complex mixtures containing significant numbers of constitutional and optical isomers. It is this complexity that makes analysis of CPs extremely challenging. Modern analytical methods employ either single or multi-dimensional gas chromatography coupled to mass spectrometric detectors operated in the negative ion mode. This chapter discusses the advances that have been made in the analysis of CPs in environmental samples with a focus on modern analytical techniques.
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Chemosensory devices with self organized structures and artificial receptors are developed for a wide field of applications. Supramolecular hosts, highly ordered liquid crystal phases and even Langmuir Blodgett films are promising recognition elements. Cage compounds such as tert- butyl-calix[n]arene show high preorganization due to their rigid walls and form highly symmetrical cavities suitable for host guest inclusion of analytes. Disturbance of the highly ordered cholesteric and nematic phases influences the optical and dielectric properties of these materials.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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eng_Latn
| 31,621 |
Toosendanin increases free-Ca(2+) concentration in NG108-15 cells via L-type Ca(2+) channels.
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AIM: ::: To examine if toosendanin (TSN) affects intracellular free-Ca(2+) concentration ([Ca(2+)](i)) in neuroblastoma pluglioma hybrid cells (NG108-15 cells). ::: METHODS: ::: The [Ca(2+)](i) was determined by laser-scanning confocal microscopic imaging technique in which Fluo-3 was used as Ca(2+) indicator. ::: RESULTS: ::: TSN induced an increase in resting [Ca(2+)](i) and in high K(+)-evoked Ca(2+) transient in differentiated NG108-15 cells. The TSN-induced increase in [Ca(2+)](i) was dose-dependent and disappeared in CdCl(2-), nifedipine-containing or Ca(2+)-free solution, and appeared after washing out the Ca(2+) channel blockers or adding Ca(2+). ::: CONCLUSION: ::: TSN increased [Ca(2+)](i) in differentiated NG108-15 cells. The [Ca(2+)](i) enhancement was due to the influx of extracellular Ca(2+) and related to L-type Ca(2+) channels.
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Abstract This review deals with the reaction mechanisms of polyaminecarboxylate complexes of different transition metals such as Fe, Mn, Ni, and Ru. Three types of chemical processes are treated, viz. water-exchange reactions, the binding of NO, and the activation of peroxides. In each case, the nature of the polyaminecarboxylate chelate and its influence on the underlying reaction mechanism are considered. In general, the complexes are either six- or seven-coordinate and all contain a coordinated water molecule. The lability of the latter is controlled by the nature of the polyaminecarboxylate chelate and the oxidation state of the metal ion. The binding of NO and the activation of peroxide are in turn controlled by the lability of the coordinated water molecule that is displaced during the interaction with these small molecules.
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eng_Latn
| 31,622 |
Physiological responses to d-fenfluramine and ipsapirone challenge correlate with indices of aggression in males with personality disorder
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Hormonal responses to challenge with the 5-HT2A/2C probe d-fenfluramine and hormonal and thermal responses to challenge with the 5-HT1A probe ipsapirone were correlated with self-report and historical assessments of aggression in a pilot sample of eight male personality-disordered individuals. Prolactin responses to d-fenfluramine and cortisol responses to ipsapirone challenge were inversely correlated with self-reported assaultiveness. Thermal responses to ipsapirone were inversely correlated with a historical assessment of aggression. Since none of these physiological indices of 5-HT system function were intercorrelated, it is possible that simultaneous assessment of these 5-HT indices may yield a more comprehensive assessment of the relationship between central 5-HT system function and aggressive behavior in humans. Language: en
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FIELD: chemistry. SUBSTANCE: invention relates to a method of producing 1-[bis(4-fluorophenyl)methyl]-4-[(2E)-3-phenylprop-2-ene-1-yl]piperazine (flunarizine). Core of invention is that flunarizine is obtained form a Fe-catalyzed combination of 1-[bis(4-fluorophenyl)methyl]-4-[(2E)-3-chloroprop-2-ene-1-yl]piperazine obtained by allylation of 1-[bis(4-fluorophenyl)methyl]piperazine with industrially available (E)-1,3-dichloropropene with phenylmagnesium-halogenide in an aprotic solvent in an inert gas atmosphere in presence of an iron salt. EFFECT: high output of flunarizine (up to 89 %), reduced cost of the process and lower toxicity of the catalyst. 5 cl, 5 ex
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eng_Latn
| 31,623 |
Restoration of descriptive inorganic chemistry
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This author breaks down the problem causing the difficulty to reinstate descriptive chemistry into the curriculum.
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A conjugated linear molecule 3 of nanometric size containing ::: two diruthenium units as redox active linkers has been synthesised; its ::: electrochemical properties indicate molecular wire-type delocalization.
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eng_Latn
| 31,624 |
Four Polyoxonibate-Based Inorganic–Organic Hybrids Assembly from Bicapped Heteropolyoxonibate with Effective Antitumor Activity
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Four novel heteropolyoxonibate-based inorganic–organic hybrids {Cu(en)2}6{GeNb12VIV2O42}·20H2O (1), {Cu(en)2}3K2Na4{GeNb12VIV2O42}·23H2O (2), {Cu(en)2}6{SiNb12VIV2O42}·18H2O (3), and {Cu(en)2}3K2Na4{SiNb12VIV2O42}·19H2O (4) (en = ethanediamine), composed of polyoxoanions [TNb12O40]16– (T = Si and Ge) and [Cu(en)2]2+ building blocks, were successfully synthesized under hydrothermal conditions by reaction of K7HNb6O19·13H2O, Cu(Ac)2·3H2O, Na2VO3, Na2SiO3, or GeO2 and en molecules. Polyoxoanion [TNb12VIV2O42]12– (T = Si and Ge) can be best described as a α-Keggin core [TNb12O40] with two [VO] units capping on its two “opened windows”. Compounds 1 and 3 are both composed of the bicapped heteropolyoxonibate core surrounded by a shell consisting of twelve [Cu(en)2]2+ groups, which represent a promising structural model toward core–shell nanostructures. Compounds 2 and 4 are also composed of a bicapped polyoxoanion [TNb12VIV2O42]12– (T = Si, Ge) decorated by three metal–organic fragments [Cu(en)2]2+, forming a t...
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In this letter, we report the singlet ground state structure of the full carotenoid peridinin by means of variational Monte Carlo (VMC) calculations. The VMC relaxed geometry has an average bond length alternation of 0.1165(10) Å, larger than the values obtained by DFT (PBE, B3LYP, and CAM-B3LYP) and shorter than that calculated at the Hartree-Fock (HF) level. TDDFT and EOM-CCSD calculations on a reduced peridinin model confirm the HOMO-LUMO major contribution of the Bu(+)-like (S2) bright excited state. Many Body Green's Function Theory (MBGFT) calculations of the vertical excitation energy of the Bu(+)-like state for the VMC structure (VMC/MBGFT) provide an excitation energy of 2.62 eV, in agreement with experimental results in n-hexane (2.72 eV). The dependence of the excitation energy on the bond length alternation in the MBGFT and TDDFT calculations with different functionals is discussed.
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eng_Latn
| 31,625 |
Effect of perindopril on left ventricular diastolic function in rat hearts with cardiac failure induced by myocardial infarction
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WC observed the effect of Perindopril (Per) on left ventricular diastolic function in rat hearts with cardiac failure induced by myocardial infarction (MI). The decrease of left ventricular end-diastolic pressure, the increase of- dP/ dtmax and the shortening of time constant of isovolumic pressure falling( T)as well as the weight losses of heart and lung were observed in the Per-treated rats as compared with the control rats.The increase of activity of superoxid dismutase (SOD) and the decrease of levels of malon-dialdehyde (MDA)and Ca2+ in heart tissue were abc observed in the Per-treated rats.The results mentioned above indicate that Per possesses a protective effect on left ventricular dlastolic function after MI and that its effect may be related to the protection of the activity of SOD and the diminution of lipid peroxidation and overload calcuim
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We demonstrated synthetically that the eight-membered heterocycles 2,6,9-triazabicyclo[3.3.1]nonanes and 1,5-diazacyclooctanes are the initial and exclusive products of the reaction, through an imino [4+4] cycloaddition, of biologically relevant amines with acrolein. The stabilities of the aminoacetals within the eight-membered heterocycles determined whether the product was subsequently transformed gradually into the 3-formyl-3,4-dehydropiperidine (FDP), which is widely used as an oxidative stress marker. The reactivity profiles discovered in this study suggested that some of the imino [4+4] cycloaddition products are reactive intermediates of FDP and contribute to the mechanisms underlying the oxidative stress response to acrolein.
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eng_Latn
| 31,626 |
Method of producing flunarizine
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FIELD: chemistry. SUBSTANCE: invention relates to a method of producing 1-[bis(4-fluorophenyl)methyl]-4-[(2E)-3-phenylprop-2-ene-1-yl]piperazine (flunarizine). Core of invention is that flunarizine is obtained form a Fe-catalyzed combination of 1-[bis(4-fluorophenyl)methyl]-4-[(2E)-3-chloroprop-2-ene-1-yl]piperazine obtained by allylation of 1-[bis(4-fluorophenyl)methyl]piperazine with industrially available (E)-1,3-dichloropropene with phenylmagnesium-halogenide in an aprotic solvent in an inert gas atmosphere in presence of an iron salt. EFFECT: high output of flunarizine (up to 89 %), reduced cost of the process and lower toxicity of the catalyst. 5 cl, 5 ex
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One way to increase efficiency and reduce pollution in transport and energetic domain is designing fuel injectors with better atomization. In this work, experiments were performed on a prefilming airblast atomizer often used in gas turbine engines. For this purpose, a new injector was designed to visualize the prefilming zone and the primary atomization together. The flow configuration corresponds to an annular liquid film sheared by inner high velocity airflows. High speed Shadowgraphy was used to observe film and spray, liquid film frequency, wave velocity and wave deformation, primary breakup regime. Finally, a link between liquid film and the primary atomization are shown first qualitatively and after quantitatively.
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eng_Latn
| 31,627 |
Dynamics of spin-polarized photoelectrons in rubidium-tetrahydrofuran solutions
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We present a Fourier transform EPR study of photoexcited rubidium-tetrahydrofuran solutions (Rb/THF), in the absence and presence of the complexing chelate 222 cryptand (Kp), Rb/THF/Kp. The temporal behavior of the EPR signals is interpreted in terms of two components participating in the complex processe, i.e., the spin-polarized photoelectrons and the solvated electrons that are coupled to the alkali-metal cations and, when present, to the cryptand molecules. The spin polarization mechanism is due to the radical pair mechanism, which is induced by charge transfer to solvent as a result of the photoabsorption
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Abstract Exposure of the dorsal skin of hairless mice to the light of a germicidal lamp under standardized conditions produces reproducible, time-dependent increases of putrescine and spermidine concentrations, and a decrease of spermine levels, concomitant with the increase of the rate of DNa synthesis. Systemic or topical treatment of the animals with α-difluoromethylornithine, an enzyme-activated irreversible inhibitor of ornithine decarboxylase, completely prevents the uv light-induced rapid formation of putrescine, and diminishes the enhancement of polyamine turnover rates. A significant effect of the drug on the rate of DNA synthesis could not be shown. The model is suitable for the study of interrelations between polyamine metabolism and cell proliferation and for the screening of compounds designed as inhibitors of polyamine biosynthesis.
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eng_Latn
| 31,628 |
Synthesis of new metalloporphyrin triads: efficient and versatile tripod optical sensor for the detection of amines.
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Zinc and manganese complexes of porphyrin triads have been synthesized and are shown to be efficient as highly sensitive and selective tripod optical sensors for amines at the picomolar level.
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Methionyl tRNA acylated within mitochondria isolated from mouse liver, has been resolved into four species by RPC-5 chromatography. All four elute prior to the three cytoplasmic methionyl tRNA species. Of the four species, two are formylated. These results suggest that iso-accepting species of met-tRNAmet exist in mouse liver mitochondria.
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eng_Latn
| 31,629 |
Cyclization of 2′-hydroxychalcones to flavones using ammonium iodide as an iodine source: An eco-friendly approach
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Ammonium iodide on exposure to air decomposes to ammonia and iodine. The in situ generated iodine was used for the cyclization of 2'-hydro- xychalcones to the corresponding flavones under solvent-free conditions in good to excellent yields. This method could serve as an attractive alternative to the existing methods for synthesis of flavones and the use of toxic molecular iodine is avoided.
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The first far infrared intermolecular vibration–rotation spectrum of the ternary van der Waals cluster has been measured near 39.5 cm−1 and assigned to an a‐type ∑ bending vibration of Ar2HCl. Spectra of both chlorine isotopes were observed and nuclear quadrupole hyperfine structure was resolved. Values of the fitted constants (rotational constants, hyperfine projections) evidence large amplitude out‐of‐plane motion, and demonstrate the sensitivity of spectroscopic observables to the three body forces operative in the Ar2HCl system. Spectroscopic predictions calculated by Hutson et al. from pairwise‐additive and ‘‘three‐body’’ corrected potential energy surfaces [J. Chem. Phys. 90, 1337 (1989)] are compared to experimental results.
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eng_Latn
| 31,630 |
Synthesis of Catechins via Thiourea/AuCl3-Catalyzed Cycloalkylation of Aryl Epoxides
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A diversity-oriented approach for the synthesis of structurally diverse catechins was achieved in good yields via thiourea/AuCl3/AgOTf-catalyzed annulations of aryl epoxides under mild conditions. This new protocol provides a highly efficient entry to a library of catechins-derived natural products, notably anti-HIV agent 8-C-ascorbyl-(−)-epigallocatechin.
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Abstract Treatment of [Ru(acac)3] (acac−=acetylacetonate) with (2,4,5-Me3C6H2)MgBr, followed by column chromatography in air, afforded the homoleptic tetraaryl-ruthenium(IV) complex [Ru(2,4,5-Me3C6H2)4] (1) in moderate yield. The product was characterized by proton NMR spectroscopy and microanalyses. Its crystal structure has also been established by X-ray crystallography.
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eng_Latn
| 31,631 |
The method for fluorinating the compound
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Quaternary ammonium cyanide and at least one chloro, bromo, sulfonyl or nitro group is substituted, the combination aryl or heteroaryl substrate, the combination thereby generating a mixture, the mixture and hexafluorobenzene, by the fact that thereby generates a fluorinated substrate, a method for preparing a fluorinated aryl or heteroaryl substrate.
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Recent advances in nanotechnology have opened a lot of new possibilities for nanomaterials application in wide variety of industrial, pharmaceutical, medicinal and environmental applications. This review aims to description of various Fourier Transform Infrared (FTIR)-based spectroscopic techniques suitable to characterize (i) different types of nanomaterials and (ii) various macroscopic samples at their nanoscale. In the introductory section, nanomaterials are classified according to their crucial properties, i.e. chemical composition, size and surface morphology. Application of traditional FTIR techniques, such as Attenuated Total Reflection (ATR), Diffuse Reflection (DRIFT) and infrared micro (spectro)scopy, for characterization of nanomaterials and nanostructures is compared with novel optical nanoscopic techniques derived from scanning probe microscopy which enable to overcome the diffraction limit and to characterize nanomaterials at molecular scale.
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eng_Latn
| 31,632 |
Why Dissolved Organic Matter Enhances Photodegradation of Methylmercury
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Methylmercury (MeHg) is known to degrade photochemically, but it remains unclear what roles naturally dissolved organic matter (DOM) and complexing organic ligands play in MeHg photodegradation. Here we investigate the rates and mechanisms of MeHg photodegradation using DOM with varying oxidation states and origins as well as organic ligands with known molecular structures. All DOM and organic ligands increased the rate of MeHg photodegradation under solar irradiation, but the first-order rate constants varied depending on the oxidation state of DOM and the type and concentration of the ligands. Reduced DOM photochemically degraded MeHg 3 times faster than oxidized DOM. Compounds containing both thiol and aromatic moieties within the same molecule (e.g., thiosalicylate and reduced DOM) increased MeHg photodegradation rates far more than those containing only aromatics or thiols (e.g., salicylate or glutathione, or their combinations). The mechanism is attributed in part to strong binding between MeHg and ...
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Abstract A convenient microwave-assisted methodology is developed for the generation of 5-chloro-3-(dimethylamino)pyrazin-2(1H)-ones. The method entails a chemoselective desulfitative removal of a phenylthioether bond upon DMF/H2O treatment in the presence of sodium carbonate, yielding the desired compounds in 73–96%.
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eng_Latn
| 31,633 |
ChemInform Abstract: Copper-Catalyzed Skeletal Rearrangements of O-Propargylic Oximes via Cleavage of a Carbon-Oxygen Bond
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Review: [recent developments in copper-catalyzed skeletal 2,3-rearrangement reactions of O-propargylic oximes to form four-membered cyclic nitrones, pyridine N-oxides, and amidodienes via N-allenylnitrone intermediates; 32 refs.
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The present invention provides a process for the preparation of an enriched carboxylic acid compositions produced by the method of composition of the carboxylic acid is included in contact with the enrichment feed in the enrichment zone. The present invention is then to remove the catalyst from the carboxylic acid composition to a method and that the resulting composition for the preparation of a catalyst removal composition.
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eng_Latn
| 31,634 |
Exercise and diet induced weight loss improves measures of oxidative stress and insulin sensitivity in adults with characteristics of the metabolic syndrome
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Obesity and insulin resistance (IR) increase the risk for coronary heart disease; however, much of this risk is not attributable to traditional risk factors. We sought to determine whether weight loss associated with supervised aerobic exercise beneficially alters biomarkers of oxidative stress and whether these alterations are associated with improvements in measures of insulin resistance. Twenty-five sedentary and overweight to obese [body mass index (BMI) = 33.0 ± 0.8 kg/m2] individuals, with characteristics of the metabolic syndrome, participated in a 4- to 7-mo weight loss program that consisted of energy restriction (reduced by ∼500 kcal/day) and supervised aerobic exercise (5 days/wk, 45 min/day at 60% Vo2 max; ∼375 kcal/day). IR and insulin sensitivity were assessed by the calculation of the homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI), respectively. Oxidative stress was assessed by oxidized LDL (oxLDL), myeloperoxidase (MPO), and low- and high- de...
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We have carried out molecular dynamics (MD) simulations and free energy calculations on the α-subtype of the human estrogen receptor ligand-binding domain (ERα LBD) complexed with a number of known agonists and putative xenoestrogens. Our dynamical simulations of ligand−receptor complexes underscore the highly structured nature of the complex and offer some interesting insights into the structure−activity relationship (SAR) for these ligands. With traditional thermodynamic integration (TI) calculations, we calculate relative binding free energies for three known agonists, in good agreement with experimental values. The sheer number of possible xenoestrogenic compounds makes an approach using traditional free energy calculations unfeasible. Instead, we have made use of a single-step perturbation methodology that allows the calculation of relative free energies for a large number of related polyaromatic hydrocarbons (PAHs) from a single simulation. Our results show good (maximum deviation 3.3 kJ mol-1) agre...
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eng_Latn
| 31,635 |
A green protocol for one-pot three-component synthesis of α-amino phosphonates catalyzed by succinic acid
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A simple, efficient, and general method has been developed for the one-pot, three-component synthesis of a-amino phosphonates from a condensation reaction of trialkyl phosphite, aldehydes, and amines in the presence of a catalytic amount of succinic acid (8.5 mol %) (for the first time) under solvent-free conditions. The advantages of this protocol are excellent yields, short reaction time, mild reaction conditions, higher availability, low costs, more environmentally friendly, lack of need for column chromatography and simple work-up procedure.
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The present paper is devoted to the investigation of spontaneous peroxy fragmentation of poly-peptide chains using human serum albumin as a model. The chain radical mechanism of this reaction hasbeen proposed. It has been shown that the chain process is initiated by the interaction of ionogenic peptidegroups with the dissolved oxygen.
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eng_Latn
| 31,636 |
Combinational biosynthesis of a fluorescent cyanobacterial holo-α-allophycocyanin in Escherichia coli
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Allophycocyanin ( APC) is a phycobiliprotein with various biological and pharmacological properties. An expression vector containing five essential genes in charge of biosynthesis of cyanobacterial APC holo-alpha subunit ( holo- ApcA) was constructed, resulting in over- expression of a fluorescent holo- ApcA in E. coli. After being cultured for 16 h, the dry cell density reached 22.5 gl(-1), and the expression of holo- HT- ApcA was up to 1 gl(-1) broth. The recombinant protein showed similar spectral features to native APC.
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Objective: To design a new synthetic technology of the anti-malarial drug lumefantrine.Methods: Industrial fluorine was used as starting material.In the presence of manganese dioxide and using glacial acetic acid as solvent,inletting hydrogen chloride gas and 2,7-dichlorofluorene were produced.Then,using anhydrous AlCl3 as catalyst,2,7-dichlorofluorene reacted with chloracetyl chloride to produce 2,7-dichloro-4-chloracetyl fluorene.Finally,the "one-pot reaction" was used for the reduction,amination and condensation reaction to obtain lumefantrine.Results and Conclusion: The total yield of this technology was over 40% based on fluorene,its processing steps were less than those of previous technologies,and the operation was simple.Thus,the new method is much more advanced and the new process route is much more suitable for industrial production.
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eng_Latn
| 31,637 |
Study on Bleach Process of Ethoxylated Lauryl Alcohol Sulfates
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Sodium hypochlorite and hydrogen peroxide are widely used in the manufacture of Ethoxylated Lauryl Alcohol Sulfates,in order to improve color quality of the product.This article discusses the dosage of both bleacher in AES with different alkyl chain structure,as well as the effect of bleach process on the product quality and performance.
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Electrocatalytic formal [2+2] cycloadditions between anodically activated enyloxy benzene and alkenes have been accomplished in a lithium perchlorate/nitromethane electrolyte solution. The enyloxy benzene moiety of these electrolytic substrates played an important role in the formation of a radical cation that could accept nucleophilic alkenes, followed by intramolecular electron transfer between the cyclobutane and phenyl ether moieties of the intermediates.
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eng_Latn
| 31,638 |
Nonlinear optical properties of 2,4,5-Trimethoxy-4-nitrochalcone: observation of two-photon-induced excited-state nonlinearities.
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We report experimental investigations of optical nonlinearities and nonlinear dynamics in acetone solution of 2,4,5-Trimethoxy-4- nitrochalcone. By performing Z-scans with femtosecond laser pulses at low excitation intensity, two-photon absorption (2PA) and third-order nonlinear refraction are measured. As laser excitation intensity exceeds a critical value, however, the interplay between third- and fifth-order nonlinearities is observed. It is also confirmed that fifth-order processes mainly originate from 2PA-induced excited-state nonlinearities by conducting femtosecond time-resolved degenerate pump-probe measurements. All the nonlinear parameters are determined unambiguously in the near infrared region of the 2PA cross-section, second-order hyperpolarizability, excited-state absorption cross-section, excited-state refraction cross-section, lifetime of excited states induced by 2PA, and critical population of the excited states in 2,4,5-Trimethoxy-4-nitrochalcone molecule.
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Refrigeration of the volatile oil of Nigella sativa L. seeds eventuates in a crystalline substance. The chemical structure of the compound was drawn from its chemical behaviour, as well as from its UV, IR, PMR and mass spectral data. The compound was found to be thymohydroquinone: confirmation of the structure was established via the preparation of its corresponding diacetate ester. The compound was found to have high antimicrobial effect against gram positive microorganisms
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eng_Latn
| 31,639 |
Binding of Translationally Controlled Tumour Protein to the N-Terminal Domain of HDM2 Is Inhibited by Nutlin-3
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Translationally Controlled Tumour Protein (TCTP), a highly conserved protein present in all eukaryotic organisms, has a number of intracellular and extracellular functions including an anti-apoptotic role. TCTP was recently shown to interact with both p53 and HDM2, inhibiting auto-ubiquitination of the latter and thereby promoting p53 degradation. In this study, we further investigated the interaction between TCTP and HDM2, mapping the reciprocal binding sites of TCTP and HDM2. TCTP primarily interacts with the N-terminal, p53-binding region of HDM2 through its highly basic domain 2. Furthermore, we discovered that Nutlin-3, a small molecule known to promote apoptosis and cell cycle arrest by blocking binding between HDM2 and p53, has a similar inhibitory effect on the interaction of HDM2 and TCTP. This result may provide an additional explanation of how Nutlin-derived compounds currently in clinical trials function to promote apoptosis in cancer cells.
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Abstract First principles calculations were carried out to study the stability and hydrogen adsorption properties of Mg/TiMn 2 interface. The surface stability and hydrogen adsorption of TiMn 2 were explored. The Mn terminated (001) is the most stable surface among the considered surfaces of TiMn 2 and TiMn 2 surface shows better hydrogen adsorption ability than the pure Mg surface. Two models coupling the Mg(0001) surface and the TiMn 2 (001) surface with different terminations were constructed to explore the Mg/TiMn 2 interface. The Mg(0001)/Mn terminated TiMn 2 (001) with interface is much more stable than that of Ti terminated system. These two interfaces both show good hydrogen adsorption ability, in which the Mn terminated interface shows − 1.62 eV of hydrogen adsorption energy. The electronic structures of the considered systems are evaluated. The negative adsorption energies of hydrogen on the surface and interface systems are further explained by the analysis of the density of states.
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eng_Latn
| 31,640 |
Electron transfer to the binuclear center in cytochrome oxidase: catalytic significance and evidence for an additional intermediate.
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We have followed, by transient kinetics, the reduction of cytochrome a3 in the presence of carbon monoxide under different experimental conditions. We have observed that the internal electron transfer rate accounts for the turnover number, and both display the same pH and temperature dependence [pKa = 7.4 and activation energy (Ea) = 14.7 +/- 0.1 kcal/mol]. Moreover, comparison of the time course of cytochrome c oxidation and cytochrome a3 reduction indicates that two electrons are transferred internally and with different rates to the oxygen-binding site. A kinetic model based on sequential internal electron transfer pathways, describing quantitatively the experimental data, is presented and discussed.
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In this article we are discussing the nature and mechanism of the huge ::: amount of heat generation in Megawatts Energy Catalyzers (E-cat) of Andrea ::: Rossi that are able to change the energetics of our civilization in general. ::: These processes are new effects of Unitary Quantum Theory and do not relate to ::: either chemical or nuclear reactions or phase transfer.
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eng_Latn
| 31,641 |
Selective Alpha-2 (α2) Receptor Agonists: Their Pharmacological Profile and Role in Therapeutics
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Alpha-2 (α2) adrenergic receptors mediate many of the physiological actions of the endogenous catecholamines adrenaline and noradrenaline, and are targets of several therapeutic agents. Selective α2 receptor agonists are currently used as antihypertensives and as adjuncts to anaesthesia, as spinal analgesics, and to treat opioid, nicotine and alcohol dependence and withdrawal in human beings. Characterisation of different sub-types of α2 receptors and recent advances in the field of drug development has helped to tap this barren field. This article is an effort to summarise these selective α2 receptor agonists and to discuss their role in therapeutics.
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We report on active control of the femtosecond photodissociation and ionization reactions of iron pentacarbonyl, Fe(CO)5, in the gas phase. The spectral phase of femtosecond laser pulses is modified in a pulse shaper, employing a learning evolutionary algorithm. Direct feedback from the experiment is used to iteratively improve the laser pulse shape according to a given optimization problem. This many-parameter optimization is compared with one-parameter control schemes and found to be more versatile, because it can sample a much more general search space. Information about the underlying reaction mechanism can be extracted from the results of the automated optimization. It is further shown that second-harmonic generation (SHG) can be used at the output of a 800 nm pulse shaper to implement 400 nm excitation experiments. The optimization procedure not simply increases the SHG efficiency but optimizes the objective given for the combined system of SHG and Fe(CO)5 photochemistry. The importance of the choic...
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eng_Latn
| 31,642 |
Photocatalytic Reduction of Artificial and Natural Nucleotide Co-factors with a Chlorophyll-Like Tin-Dihydroporphyrin Sensitizer
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An efficient photocatalytic two-electron reduction and protonation of nicotine amide adenine dinucleotide (NAD+), as well as the synthetic nucleotide co-factor analogue N-benzyl-3-carbamoyl-pyridinium (BNAD+), powered by photons in the long-wavelength region of visible light (λirr > 610 nm), is demonstrated for the first time. This functional artificial photosynthetic counterpart of the complete energy-trapping and solar-to-fuel conversion primary processes occurring in natural photosystem I (PS I) is achieved with a robust water-soluble tin(IV) complex of meso-tetrakis(N-methylpyridinium)-chlorin acting as the light-harvesting sensitizer (threshold wavelength of λthr = 660 nm). In buffered aqueous solution, this chlorophyll-like compound photocatalytically recycles a rhodium hydride complex of the type [Cp*Rh(bpy)H]+, which is able to mediate regioselective hydride transfer processes. Different one- and two-electron donors are tested for the reductive quenching of the irradiated tin complex to initiate t...
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The paper reviews the development of catalytic spectrophotometric determination of nitrite, including the indicator reaction, detection limit, linear range and applications of the methods. It also puts forward the developing orientation for a high sensibility analytical method.94 references are cited.
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eng_Latn
| 31,643 |
Amantadine inhibits hepatitis A virus internal ribosomal entry site-mediated translation in human hepatoma cells.
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The effect of six drugs (amantadine, glycyrrhizin, ribavirin, ursodeoxycholic acid, alcohol, and IFN) on HAV RNA translation from the HAV internal ribosomal entry site (IRES) was investigated using a bicistronic reporter construct containing HAV IRES as intragenic spacer. Huh-7 cells and derivatives were transfected with in vitro transcripts, and the reporter gene activity was determined. IFN suppressed both cap-dependent and HAV IRES-dependent translation, while amantadine specifically inhibited HAV IRES-dependent translation. In contrast to IFN, by reporter assay, amantadine did not activate the interferon-stimulated response element (ISRE) or interferon gamma-activated sequence (GAS)-associated pathways. Immunoblot analysis revealed that amantadine had no effect on PKR and on IFN-regulatory factor-1 (IRF-1) expression. These findings demonstrated a novel antiviral effect of amantadine against HAV with or without HCV infection.
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We explore the protonation states of benzohydroxamic acid adsorbates bound to the {101} facet of TiO2 anatase by using a combination of density functional theory, simulations of UV–vis spectra based on a tight-binding Hamiltonian, and direct comparisons to experimental measurements. We find that the characteristic red-shifted spectrum of nonmethylated, relative to the methylated, hydroxamic acids can only be explained by proposing a monodeprotonated monodentate mode as the main adsorption mode. The reported analysis suggests a simple, yet general, spectroscopic method based on UV–vis absorption measurements and tight-binding calculations for inferring changes of pKa of molecular adsorbates interacting with semiconductor electrode surfaces.
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eng_Latn
| 31,644 |
Antioxidant Activity of 3 -Methylthiopropylamine Hydrochloride
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Antioxidant activities of various amino acids and some of their related substances on the autoxidation of sodium lenolenate in aqueous system were examined by TBA method. As the results, 3-methylthiopropylamine hydrochloride (MTPA) was found to be most effective in antioxidant activity among the substances tested. Also, it was an unique characteristic of MTPA that it was quite soluble in organic solvents, fats and oils as well as in water. At a temperature of less than 100°C, MTPA was quite stable in aqueous solution over whole pH range. Acute toxicity test of MTPA by oral administration of mice has indicated that LD50 of MTPA was 4.5 g per kg.
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Multifunctional-material-integrated various properties have been an attractive research field. In spite of persistent explorations into such materials, the conditions of coexistence are still confused. Organic–inorganic hybrid compounds are appropratie for designing these materials because of both their rich properties and flexible compositions. Here, a perovskite-type organic–inorganic hybrid compound, (Hmpy)MnCl3 (1; Hmpy = N-methylpyrrolidinium), with temperature, light, and electric stimuli-response characteristics has been rationally designed and synthesized. This hybrid compound shows a dielectric anomaly, a broad dielectric dispersion of the temperature range from 296 to 400 K, and brilliant red fluorescence at 632 nm with a high quantum yield of 54.54% under UV excitation. The coexistence of temperature, optical, and electric multiple stimuli-response properties in 1 demonstrates that our finding has a profound influence on the further exploration of the novel multifunctional materials.
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eng_Latn
| 31,645 |
Catalytic Conversion of Ethanol to n-Butanol Using Ruthenium P–N Ligand Complexes
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We report several ruthenium catalysts incorporating mixed donor phosphine-amine ligands for the upgrade of ethanol to the advanced biofuel n-butanol, which show high selectivity (≥90%) at good (up to 31%) conversion. In situ formation of catalysts from mixtures of [RuCl2(η6-p-cymene)]2 and 2-(diphenylphosphino)ethylamine (1) shows enhanced activity at initial water concentrations higher than those of our previously reported diphosphine systems. Preliminary mechanistic studies (electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy) suggest the possibility of ligand-assisted proton transfer in some derivatives.
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Abstract The processes occurring during electron irradiation of cis-polybutadiene have been investigated. The concentration of unsaturated bonds decays during irradiation with the formation of intermolecular crosslinks, intramolecular cyclic structures and polyene groups. The decay processes can be described by equations which approximate to first order kinetics. Rate constants for the decay processes have been estimated from the experimental data.
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eng_Latn
| 31,646 |
Histone deacetylase inhibitor valproic acid suppresses the growth and increases the androgen responsiveness of prostate cancer cells.
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We identified the molecular target by histone deacetylase (HDAC) inhibitors for exploring their potential prostate cancer (PCa) therapy. Upon HDAC inhibitors-treatment, LNCaP cell growth was suppressed, correlating with increased cellular prostatic acid phosphatase (cPAcP) expression, an authentic protein tyrosine phosphatase. In those cells, ErbB-2 was dephosphorylated, histone H3/H4 acetylation and methylation increased and cyclin proteins decreased. In PAcP shRNA-transfected C-81 cells, valproic acid (VPA) efficacy of growth suppression was diminished. Further, VPA pre-treatment enhanced androgen responsiveness of C-81, C4-2 and MDA PCa2b-AI cells. Thus, cPAcP expression is involved in growth suppression by HDAC inhibitors in PCa cells, and VPA pre-treatments increase androgen responsiveness.
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Electronic and geometric structures at the water-amorphous silica nanoparticle (NP) interface are determined as a function of suspension pH using a combination of X-ray photoelelectron spectroscopy (XPS) from a liquid microjet, solid-state nuclear magnetic resonance (NMR), and density functional theory (DFT). We provide direct spectroscopic evidence of the existence of (de)protonated silanol groups at the liquid–NP interface and give a microscopic description of the interface structure. The (de)protonated silanol groups, ≡Si–OH2+ and ═Si–(OH)(OH2+) in acidic suspension and ≡Si–O– and ═Si–(OH)(O–) in basic, give rise to well-resolved peaks in the Si 2p spectra that allow their identification and subsequent assignment by DFT. The change in surface potential at the silica NP surface as a function of pH can be directly measured by XPS and allows for an estimate of the fraction of silanol groups that become (de)protonated at the pH of the experiments. In agreement with DFT calculations, NMR is unable to direct...
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eng_Latn
| 31,647 |
SYNTHESES OF 2,6-DIMETHYLANILINE
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Six synthetic routes of 2,6-dimethylaniline are reviewed. Theirreaction conditions, yields and limitations are given.
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The degradation products of diclofenac in aqueous dosage form in accelerated storage conditions were characterized by electrospray ionization-ion trap mass spectrometry (ESI-MS). Liquid chromatography (LC)-MS analyses revealed the presence of three degradation products. ESI-MS(n) spectra were used to study diclofenac fragmentation in detail and to characterize the structures of degradation products. A previously described degradation product, formed by a cyclization reaction of diclofenac producing the indolinone derivative, was found. As any hydroxylated product was found, no oxidation seems to occur in the dosage form used. On the contrary, two degradates have been detected and identified, leading to a primary alcohol structure or an aldehyde function in place of the acetate group of diclofenac.
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yue_Hant
| 31,648 |
Photochemical study of the interaction of phenothiazine derivatives with spin labelled lecithin multibilayers.
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Abstract Nitroxide free radicals are destroyed by ultraviolet irradiation in the presence of phenothiazine derivatives. This property has been used in order to determine the type of interaction of these drugs with spin-labelled lecithin multibilayers. Kinetic measurements of the spin label signal decay under irradiation have shown that chlorpromazine and perphenazine are preferentially located in the polar part of the bilayer, whereas promethazine and oxidized derivatives of chlorpromazine are found principally in the hydrophobic part.
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Introduction Poly(3-alkylthiophenes) (P3ATs), as a new kind of soluble, fusible and processable conductive polymers, have attracted a great interest and much attention of chemists and physicists[1,2]. It has been widely accepted that P3ATs can form similar layered structures with alkyl side chains being oriented in the lateral a-axis direction[3-6]. Moreover, when the number of the carbon atoms in the alkyl side chains is more than 10, some orderly arrangements of the side chains will occur between the layers[4].
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eng_Latn
| 31,649 |
Microalbuminuria in Type 2 Diabetic Patients: A Cross-Sectional Study of Frequency, Sex Distribution and Relation to Hypertension
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We studied 112 type 2 diabetic patients. Fourteen patients had frank proteinuria, and 37 of the remaining 98 had microalbuminuria which was more frequent in men than in women (P<0·02). Hypertension was found in 47 of the patients, equally distributed between sexes. Male diabetics with microalbuminuria had higher systolic blood pressure than diabetics without microalbuminuria (P<0·02). Body mass index was higher in both sexes with hypertension compared to patients without hypertension. In the hypertensive men plasma C-peptide values were higher compared to patients without hypertension (P<0·01) irrespective of the presence of microalbuminuria. A positive correlation between blood pressure and C-peptide was found (P<0·01) in the men. We suggest that gender should be taken into account in the analysis and interpretation of microalbuminuria in type 2 diabetes.
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Abstract Amino modified SBA-15 (SBA-NH 2 ) was used to immobilize vanadyl (VO 2+ ) and cupric (Cu 2+ ) ions, giving SBA-NH 2 -VO 2+ and SBA-NH 2 -Cu 2+ catalysts, respectively, and the as-prepared catalysts were characterized by XRD, XPS, TEM and Nitrogen adsorption–desorption technologies. The catalytic performance of the SBA-NH 2 -VO 2+ catalysts for the oxidation of HMF can be enhanced by the use of SBA-NH 2 -Cu 2+ as the co-catalyst. Several important reaction parameters were investigated, and it was found that the reaction solvent showed a great effect on the oxidation of HMF. The highest HMF conversion and product selectivity were obtained in aromatic solvents. The highest HMF conversion reached 98.8% at 110 °C in 4-chlorotoluene, affording DFF and 2,5-furandicarboxylic acid (FDCA) with yields of 28.9% and 62.7%, respectively. More importantly, the catalysts could be recycled and showed no significant decrease of their catalytic activities.
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eng_Latn
| 31,650 |
A new route to peroxynitrite: a role for xanthine oxidoreductase
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Peroxynitrite, a potent oxidising, nitrating and hydroxylating agent, results from the reaction of nitric oxide with superoxide. We show that peroxynitrite can be produced by the action of a single enzyme, xanthine oxidoreductase (XOR), in the presence of inorganic nitrite, molecular oxygen and a reducing agent, such as pterin. The effects of oxygen concentration on peroxynitrite production have been examined. The physiologically predominant dehydrogenase form of the enzyme is more effective than the oxidase form under aerobic conditions. It is proposed that XOR-derived peroxynitrite fulfils a bactericidal role in milk and in the digestive tract.
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From the 1H and 13C NMR spectra of angularly condensed triazolobenzothiazine derivatives it was established that these compounds can be classified into two conformation types, depending on the substituents. The 10-methyl-3-carbethoxy derivatives are cis-anellated, conformationally flexible systems, where one of the aromatic hydrogens (H-9) and one of the methoxy substituents (8-OMe) of the benzothiazine skeleton on the one hand, and the 1-aryl ring on the other, lie close to each other in the preferred conformer. By assuming this conformation, the molecules avoid the steric hindrance of the 10-Me and 1-aryl groups. All compounds unsubstituted on the angular C-10 atom, and the 3-aryl-substituted derivatives of the 10-Me analogues, occur in a different conformation, containing the 1-aryl ring well removed from H-9 and the 8-OMe group.
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eng_Latn
| 31,651 |
CNDO can be used for both closed shell molecules , where the electrons are fully paired in molecular orbitals and open shell molecules , which are radicals with unpaired electrons .
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CNDO can be used for closed shell molecules , where the electrons are fully paired in molecular orbitals .
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The evidence consists of feather impressions , or convincing skeletal or chemical evidence . Skeletal evidence would be the presence of quill knobs ( the anchor points for wing feathers on the forelimb ) or a pygostyle ( the fused vertebrae at the tail tip which often supports large feathers ) .
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eng_Latn
| 31,652 |
It is produced with high efficiency by reducing sodium chlorate in a strong acid solution with a suitable reducing agent such as methanol , hydrogen peroxide , hydrochloric acid or sulfur dioxide .
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Methanol ( an alcohol ) , sulfur dioxide ( a gas made by burning sulfur ) , hydrochloric acid ( a common acid ) , or hydrogen peroxide can be used .
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Cyclopropylcarbinyl cations can be studied by NMR : In the NMR spectrum of a dimethyl derivative , two nonequivalent signals are found for the two methyl groups indicating that the molecular conformation of this cation not perpendicular ( as in A ) but is bisected ( as in B ) with the empty p-orbital and the cyclopropyl ring system in the same plane : In terms of bent bond theory , this preference is explained by assuming favorable orbital overlap between the filled cyclopropane bent bonds and the empty p-orbital .
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eng_Latn
| 31,653 |
What does organocopper compounds reactions toward oxygen form?
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Compounds that contain a carbon-copper bond are known as organocopper compounds. They are very reactive towards oxygen to form copper(I) oxide and have many uses in chemistry. They are synthesized by treating copper(I) compounds with Grignard reagents, terminal alkynes or organolithium reagents; in particular, the last reaction described produces a Gilman reagent. These can undergo substitution with alkyl halides to form coupling products; as such, they are important in the field of organic synthesis. Copper(I) acetylide is highly shock-sensitive but is an intermediate in reactions such as the Cadiot-Chodkiewicz coupling and the Sonogashira coupling. Conjugate addition to enones and carbocupration of alkynes can also be achieved with organocopper compounds. Copper(I) forms a variety of weak complexes with alkenes and carbon monoxide, especially in the presence of amine ligands.
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Even interpreting the hydrogen data (including safety data) is confounded by a number of phenomena. Many physical and chemical properties of hydrogen depend on the parahydrogen/orthohydrogen ratio (it often takes days or weeks at a given temperature to reach the equilibrium ratio, for which the data is usually given). Hydrogen detonation parameters, such as critical detonation pressure and temperature, strongly depend on the container geometry.
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eng_Latn
| 31,654 |
Using the \chemfig package to draw inorganic compounds I'm trying to draw a similar molecule as the picture below using the \chemfig package, but don't really know where to start. How would I do it?
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Counter ions and charge of a complex how can I add the charge and the counter ions to my complex? I'm using chemfig. \schemestart \chemname{\chemleft[\chemfig{Ni (<:[1]OH_2) (-[2]OH_2) (<:[3]OH_2) (<[5]OH_2) (-[6]OH_2) (<[7]OH_2) }\chemright]}{\ce{[Ni(OH2)6]Cl2}} \schemestop Thanks!
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How to add a gif file to my LaTeX file? Related: I have an image file -- a gif file, which is the graph of a function. How do I add it to a LaTeX file? Will it come out OK in the subsequent pdf file?
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eng_Latn
| 31,655 |
How many hours did you guys spend doing homework or studying for that class? How many other classes did you take during the same semester you were taking O. chem? Thanks!
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For every one hour of class, 3 hours of study is recommended. If you want succeed Organic, try this time table. Lab will take 3 hours in class. To write the report 6 to seven hours will need to take place.\nTake General Chem at the same time, many things overlap.\nThen take 2 classes that are not BIO or MATH.
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To visualize (C6H5)2CHBr, you have to identify the "side groups". Obvious Br is one side group and so is one H. Then you have two phenyl side groups so that leaves you that carbon to build on. The molecule one carbon bound to two phenyl groups, one hydrogen and one bromine, each with a single bond.\n\nOK, let's build on that. You are now going to react it with ethanol and you want to know what mechanism to expect. Since Teach didn't show you the products, you're going to have to think about this one. First, analyze what type of molecules you have. The first molecule we spoke of, what type of carbon is the main carbon (primary, secondary, tertiary)? What type of reaction (Sn1 or E1) does that type of carbon favor? How about the ethanol?\n\nActually, the alpha carbon in ethanol, being a primary carbon, would favor Sn2 but that's not an option. OH is an awful leaving group and alkanes don't like to carry a charge. So we can rule the carbon out.\n\nThe problem must revolve around diphenylmethylbromide. Having two phenyls would stabilize a positive charge fairly well and that is the first step for both E1 and Sn1 mechanisms. So, which one is it? The big giveaway is that En reactions are called elimination for a reason. They lose a pair of substituents to form a double or triple bond, always a higher order bond. Can there be any higher order bonds formed in this molecule? How about Sn1, then? That would result in (C6H5)2CH(OC2H5) + HBr. Is this more likely than elimination? Would this be endothermic or exothermic?\n\nThat's as much as I'm going to do. The rest is for you, as you only really needed to know the structure of the first molecule. But I hope this helps you understand what you are doing.\n\nGood luck.
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eng_Latn
| 31,656 |
Please outline for me the chemical shift patterns of all the protons in NMR spectrum of SALICYLIC ACID. Thanks!
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Below is the spectrum for acetasalicylic acid. There will only be a small difference between the chemicals shifts in the aromatic hydrogens between the two compounds. Also, you will obviously not have the singlet from the 3 methyl hydrogens.\n\nThe second link shows the spectrum in methanol, but its kinda hard to see.
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[osdn developer] September 19, 2002 \n... that has been written for the Mnet project is a file-sharing application which ... sid=02/09/18/0459236 I have just submitted a patch that allows for the color ...mail-archive.com/[email protected]/msg00095.html - 59k - Cached - More from this site \nTry this site and see if it offers what you need.
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eng_Latn
| 31,657 |
PubChem Substance and Compound databases
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PubChem: a public information system for analyzing bioactivities of small molecules
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General Stability of Stepwise Waveform of an Adiabatic Charge Recycling Circuit With Any Circuit Topology
|
yue_Hant
| 31,658 |
An efficient representation for irradiance environment maps
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Applications of irradiance tensors to the simulation of non-Lambertian phenomena
|
Immunomodulatory Properties of Defensins and Cathelicidins
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eng_Latn
| 31,659 |
Waveform design for QAM-FBMC systems
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5GNOW: non-orthogonal, asynchronous waveforms for future mobile applications
|
Antioxidant activity and phenolic compounds of 112 traditional Chinese medicinal plants associated with anticancer
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eng_Latn
| 31,660 |
what does iodoform test indicate
|
Iodoform Reaction. The iodoform test indicates the presence of an aldehyde or ketone in which one of the groups directly attached to the carbonyl carbon is a methyl group. Such a ketone is called a methyl ketone. In the iodoform test, the unknown is allowed to react with a mixture of iodine and base.Hydrogens alpha to a carbonyl group are acidic and will react with base to form the anion, which then reacts with iodine to form an alpha-iodo ketone.uch a ketone is called a methyl ketone. In the iodoform test, the unknown is allowed to react with a mixture of iodine and base. Hydrogens alpha to a carbonyl group are acidic and will react with base to form the anion, which then reacts with iodine to form an alpha-iodo ketone.
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The iodoform test or iodoform reaction is a qualitative chemical test for the detection of ketones and aldehydes carrying an alpha methyl group. The reagents are iodine and sodium hydroxide.Only methyl ketones, or alcohols with the feature: CH3CH(OH)-R may undergo this reaction.The iodoform test or reaction is a chemical reaction where iodoform (CHI3) is produced by the multiple halogenation of a methyl ketone (a molecule containing the R-CO-CH3 group) in the presence of a base. R may be H, alkyl or aryl.
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eng_Latn
| 31,661 |
define thiols
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Thiol with a blue-highlighted sulfhydryl group. In organic chemistry, a thiol (/ËθaɪËÉËl/ , /ËθaɪËÉl/) is an organosulfur compound that contains a carbon-bonded sulfhydryl (âCâSH or RâSH) group (where R represents an alkane, alkene, or other carbon-containing group of atoms).
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Cysteine contains a free thiol group, which is more nucleophilic than amines and is generally the most reactive functional group in a protein. Thiols, unlike most amines, are generally reactive at neutral pH, and therefore can be coupled to other molecules selectively in the presence of amines (Equation 2). This selectivity makes the thiol group the linker of choice for coupling proteins.
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eng_Latn
| 31,662 |
is nonyl phenol svhc
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53 6 CONCLUSIONS ON THE SVHC PROPERTIES 6.1 PBT, vPvB assessment Not assessed for the identification of this substance as SVHC in accordance with Article 57(f). 6.2 CMR assessment Not assessed for the identification of this substance as SVHC in accordance with Article 57(f).ue to the even slower degradation of 4-nonylphenol compared to 4-NP1-2EO (DegT50 46.2 days (primary degradation) to no elimination after 703 day in anaerobic freshwater sediment-depending on linear or branched isomers), it can be assumed that the formation of 4-nonylphenol exceeds its degradation.
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It is not to be confused with carbonic acid. Phenol, also known as carbolic acid, is an aromatic organic compound with the molecular formula C6H5OH. It is a white crystalline solid that is volatile. The molecule consists of a phenyl group (âC6H5) bonded to a hydroxyl group (âOH). It is mildly acidic and requires careful handling due to its propensity to cause chemical burns. Phenol was first extracted from coal tar, but today is produced on a large scale (about 7 billion kg/year) from petroleum.
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eng_Latn
| 31,663 |
is polyaniline properties
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This interest is due to the rediscovery of high electrical conductivity. Amongst the family of conducting polymers and organic semiconductors, polyaniline has many attractive processing properties. Because of its rich chemistry, polyaniline is one of the most studied conducting polymers of the past 50 years.he emeraldine (n = m = 0.5) form of polyaniline, often referred to as emeraldine base (EB), is neutral, if doped (protonated) it is called emeraldine salt (ES), with the imine nitrogens protonated by an acid. Protonation helps to delocalize the otherwise trapped diiminoquinone-diaminobenzene state.
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Rating Newest Oldest. Best Answer: Polygenic Inheritance: Human skin color is a good example of polygenic (multiple gene) inheritance. Assume that three dominant capital letter genes (A, B and C) control dark pigmentation because more melanin is produced.
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eng_Latn
| 31,664 |
what is hydrodehalogenation
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The stabilizing effects of this interaction. can produce highly inert compounds, which can pose a problem for waste management. Hydrodehalogenation is. a sub-field of hydrogenation chemistry where a halogen is effectively replaced with hydrogen and has. significant applications in many of the same areas as basic hydrogenation. -Conclude systematic survey of reduction in simple aromatic halides.
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Palladium-catalyzed hydrodehalogenation of aryl halides using paraformaldehyde as the hydride source: high-throughput screening by paper-based colorimetric iodide sensor.
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eng_Latn
| 31,665 |
aminophenol definition
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p- aminophenol. /p- ami·no·phe·nol/ (-fe´nol) a dye intermediate and photographic developer and the parent compound of acetaminophen; it is a potent allergen that causes dermatitis, asthma, and methemoglobinemia. Want to thank TFD for its existence?
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p-HOC6H4NO2 A phenol in which an amino (âNH2) group is located on the benzene ring of carbon atoms para (p) to the hydroxyl (âOH) group; used as a photographic developer and as an intermediate in dye manufacture. the Para isomer of aminophenol. White crystals, melting point 186°C. The structure of Para-aminophenol is.
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eng_Latn
| 31,666 |
is iodine monochloride a compound
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Iodine monochloride is the chemical compound with the formula ICl. It is a red-brown compound that melts near room temperature. Because of the difference in the electronegativity of iodine and chlorine, ICl is highly polar and behaves as a source of I+. »
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Iodine Monochloride Avail from us a sophisticated range of Iodine Monochloride, that are widely used as an iodinating agents and in Wijs' solution to determine iodine numbers. These compounds proves a useful reagent in organic synthesis and is widely used as a source of electrophilic iodine in the synthesis of certain aromatic iodides. Further, IMC are generally red-brown compound that melts near room temperature and find wide applications in various chemical industries. more..
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eng_Latn
| 31,667 |
what are amines found in
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Importance in Food [edit]. Biogenic amines can be found in all foods containing proteins or free amino acids and are found in a wide range of food products including fish products, meat products, dairy products, wine, beer, vegetables, fruits, nuts and chocolate.iogenic amines are organic bases with low molecular weight and are synthesized by microbial, vegetable and animal metabolisms. In food and beverages they are formed by the enzymes of raw material or are generated by microbial decarboxylation of amino acids.
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The black lines where it has rested on the grill will contain heterocyclic amines. Heterocyclic amines are a group of chemical compounds, many of which can be formed during cooking. They are found in meats that are cooked to the well done stage, in pan drippings and in meat surfaces that show a brown or black crust.
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eng_Latn
| 31,668 |
what is oxalic water
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Oxalic acid. Oxalic acid, also called Ethanedioic Acid, a colourless, crystalline, toxic organic compound belonging to the family of carboxylic acids. Oxalic acid is widely used as an acid rinse in laundries, where it is effective in removing rust and ink stains because it converts most insoluble iron compounds into a soluble complex ion.
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Oxalate occurs in many plants, where it is synthesized by the incomplete oxidation of carbohydrates. Oxalate-rich plants include fat hen (lamb's quarters), sorrel, and several Oxalis species. The root and/or leaves of rhubarb and buckwheat are high in oxalic acid.xalate, the conjugate base of oxalic acid, is an excellent ligand for metal ions. It usually binds as a bidentate ligand forming a 5-membered MnO 2 C 2 ring. An illustrative complex is potassium ferrioxalate, K 3 [Fe(C 2 O 4) 3 ].
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eng_Latn
| 31,669 |
what are acid anhydrides
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From Wikipedia, the free encyclopedia. Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH 3 CO) 2 O. Commonly abbreviated Ac 2 O, it is the simplest isolable anhydride of a carboxylic acid and is widely used as a reagent in organic synthesis.ike most acid anhydrides, the carbonyl carbon of acetic anhydride is a potent electrophile as the leaving group for each carbonyl carbon (a carboxylate) is a good electron-withdrawing group.
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An introduction to acid anhydrides including a general look at their reactivity. Reactions of acid anhydrides with oxygen compounds. . . The reactions of acid anhydrides with water, alcohols and phenols (including the manufacture of aspirin). Reactions of acid anhydrides with nitrogen compounds. . .The reactions of acid anhydrides with ammonia and primary amines. Go to menu of other organic compounds. . .Go to Main Menu. . .he reactions of acid anhydrides with water, alcohols and phenols (including the manufacture of aspirin). Reactions of acid anhydrides with nitrogen compounds. . . The reactions of acid anhydrides with ammonia and primary amines.
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eng_Latn
| 31,670 |
Stable photoinduced charge separation in heptacene
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Heptacene, generated in inert gas matrices by photobisdecarbonylation of a bridged α-diketone precursor, undergoes ionization into radical anion and radical cation upon UV irradiation.
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By means of single crystal X-ray analysis of dendranthemoside A pentaacetate, the absolute configuration of the asymmetric center at the 9-position was determined to be R. The configurations of three other positions, which had been determined to be 3S, 5R and 6S by application of β-D-glucosylation induced shift trends, were verified.
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eng_Latn
| 31,671 |
Large Highly Modular Narrow Gap Electrolytic Flow cell and Application in Dehydrogenative Cross-Coupling of Phenols
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The successive scale-up of electrochemical reactions is crucial with regards to the implementation of technical electro-organic syntheses. Therefore, we developed a scalable modular parallel plate electrochemical flow cell. One distinctive feature of this flow cell is that the temperature of the electrodes can be easily controlled from the back side via an external cooling circuit. That enables a high reproducibility of electrochemical conversions. By keeping the gap between the electrodes narrow, small amounts or no supporting electrolyte is required. The practicability and performance of the novel flow cell was validated by three different anodic phenol-phenol cross-couplings as test reactions.
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This paper presents a novel p tubular linear generator (PMTLG) buoy sy convert the linear motion of the ocean wav energy. The design incorporates no working water airgap bearing surface integration betw components. The internal generator design w addition to the system integration with the bu the linear test bed performance results.
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eng_Latn
| 31,672 |
Inorganic bromine compounds adopt a variety of oxidation states from − 1 to +7 .
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Bromine forms compounds in many oxidation states : -1 , +1 , +3 , +5 , and ( sometimes ) +7 .
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Ross Brann , a professor of Judeo-Islamic classes at Cornell University in Ithaca , stated that Wikipedia is without a way to expertly review , saying , `` They could make up your life if they wanted to . ''
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eng_Latn
| 31,673 |
Arsine reacts with mercury ( II ) bromide : The white mercury ( II ) bromide will turn yellow , brown , or black if arsenic is present in the sample .
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The arsenic is reacted with hydrogen to make arsine , which reacts with mercury ( II ) bromide to turn it yellow or brown .
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Urey speculated that the early terrestrial atmosphere was probably composed of ammonia , methane and hydrogen ; it was one of his Chicago graduate students , Stanley L. Miller , who showed that , if such a mixture be exposed to electric sparks and to water , it can interact to produce amino acids , commonly called the `` building blocks of life '' ( see Miller-Urey experiment ) .
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eng_Latn
| 31,674 |
Halide compounds are known for both oxidation states .
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Tin forms chemical compounds in two oxidation states : +2 and +4 .
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[ 8 ] Hale was homeschooled .
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eng_Latn
| 31,675 |
Statistical universals reveal the structures and functions of human music
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Universal Recognition of Three Basic Emotions in Music
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Synergistic effects in La/N codoped TiO2 anatase (101) surface correlated with enhanced visible-light photocatalytic activity.
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eng_Latn
| 31,676 |
can an oxidative state be a fraction
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exists and is an alternate of . No. it can't be fractional. However you can get fractional answers uch as Fe in Fe3O4 where the average oxidation state is 2.666.... You need to know something about the structure that will tell you what oxidation numbers of the Fe in this case two Fe with +3 and one Fe with +2 in each formula unit. No. it can't be fractional. <br /><br /> However you can get fractional answers uch as Fe in Fe3O4 where the average oxidation state is 2.666.... You need to know something about the structure that will tell you what oxidation numbers of the Fe in this case two Fe with +3 and one Fe with +2 in each formula unit.
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Related to cytochromes: cytochrome oxidase, ferredoxin, Cytochrome P450, Electron transport chain cytochromes heme-containing proteins in the electron transport chain that can be alternately in an oxidized or reduced state. See also oxidative phosphorylation.
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eng_Latn
| 31,677 |
Resolution of nodulocystic acne with oral dapsone.
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Severe Nodulocystic Acne not Responding to Isotretinoin Therapy Successfully Treated with Oral Dapsone
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Severe Nodulocystic Acne not Responding to Isotretinoin Therapy Successfully Treated with Oral Dapsone
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eng_Latn
| 31,678 |
Which graft is better for an acl reconstruction?
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What is the best graft for ACL reconstruction?
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What are the best treatment for acne?
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eng_Latn
| 31,679 |
benefits of zinc for acne
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Why zinc works for acne is still unclear but zinc may have the power to: 1 Help kill the acne-causing bacteria P. acnes. 2 Reduce the redness and inflammation of acne lesions. 3 Decrease skin oil production.
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Zinc deficiency is caused by inadequate intake or absorption, increased zinc excretion, or increased bodily need for zinc. Zinc deficiency symptoms include growth and development problems, hair loss, diarrhea, impotence, eye and skin conditions, and loss of appetite.inc taken by mouth or applied to the skin seems to be a safe and effective treatment for acne. However, some results are conflicting, and many studies used combination treatments. More research on the effects of zinc alone are needed.
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eng_Latn
| 31,680 |
Home remedy to clear acne quickly?
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Natural home remedies for clear skin?
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How do you get rid of your viruses?
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eng_Latn
| 31,681 |
How do you pop a pimple gently?
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What do you do if you cant pop a pimple?
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What do you do if you cant pop a pimple?
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eng_Latn
| 31,682 |
How does your ear pop?
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Does popping your ears have consequences?
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What do you do if you cant pop a pimple?
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eng_Latn
| 31,683 |
How do you completely clear acne?
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Can female cum clear your acne?
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Natural home remedies for clear skin?
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eng_Latn
| 31,684 |
Does poping pimples make more pimples?
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Does popping a pimple make more come up?
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What do you do if you cant pop a pimple?
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eng_Latn
| 31,685 |
Who to get rid of a pimple in three days?
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What is aquick way to get rid of a pimple?
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What if you never masturbate and never have a wet dream at age 13?
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eng_Latn
| 31,686 |
How d you get rid of bacteria?
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Does bacteria get rid of wastes?
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What is aquick way to get rid of a pimple?
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eng_Latn
| 31,687 |
How tighten loose skin under my neck?
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How do you tighten loose skin on the face?
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How do you tighten loose skin on the face?
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eng_Latn
| 31,688 |
Does putting toothpaste on acne help cure it fast?
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Is toothpaste a cure for acne?
|
Is toothpaste a cure for acne?
|
eng_Latn
| 31,689 |
Will this product be work on chest acne as well or just for back?
|
Seems to work better at clearing spots on my chest than back. The few acne spots I had on my chest have faded away.
|
I'm not sure, I'm sorry. I wish I could answer that. It's worth a try though! Consult a dermatologist first though and check to see what he/she says. Good luck!
|
eng_Latn
| 31,690 |
Is this product okay to use on the face or would it be too think/clog the pores?
|
I had this product for a long time. It works great for my face. I definitely think it's okay to use. Never had problems using it.
|
I have not had a problem yet and I have had this on my counter for 3.5 months.
|
eng_Latn
| 31,691 |
How do you apply it? all over your face or?
|
I just apply a thin layer over problem areas after I wash my face. This has nothing to do with this product, but check out: thelovevitamin.com. If you're suffering from acne, she has great advice. Good luck!
|
I've been using mine morning and evening for about 2 months and I have about half a bottle left. I would say 3-6 months.
|
eng_Latn
| 31,692 |
How do I get rid of pimples permanently?
|
How do I get rid of scalp acne?
|
How do I quit smoking cigarettes forever? Any easiest way?
|
eng_Latn
| 31,693 |
How do I get rid of acne on nose?
|
How do I get rid of acne on my nose?
|
What are some natural remedies for a flawless skin (no pores/no zits/etc.) that actually work?
|
eng_Latn
| 31,694 |
Is there a cure for acne? Why or why not?
|
Why haven't we found a cure to acne?
|
How do I get rid of a zit on my ear?
|
eng_Latn
| 31,695 |
What products should I use to get rid of acne quickly?
|
How do I get rid of scalp acne?
|
How can I remove black spots on my face?
|
eng_Latn
| 31,696 |
How can I get rid of acne and scars?
|
"How do I get rid of acne and acne…?
|
How do you lose belly fat?
|
eng_Latn
| 31,697 |
How can I get rid of the visible pores on my nose?
|
How do you get rid of visible pores on your nose?
|
How do I unpop a clogged ear?
|
eng_Latn
| 31,698 |
Which is the best treatment for vitiligo?
|
What is the best treatment of vitiligo?
|
How did you get rid of acne scars on face?
|
eng_Latn
| 31,699 |
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