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Stability constants of the Li+, Na+, H3O+, NH4+, Ag+, and K+ complexes of the cone conformer of tetraethyl p-tert-butyltetrathiacalix[4]arene tetraacetate in nitrobenzene saturated with water
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AbstractFrom extraction experiments in the two-phase water-nitrobenzene system and γ-activity measurements, the stability constants of the tetraethyl p-tert-butyltetrathiacalix[4]arene tetraacetate (cone)·M + complexes (M + = Li + , H 3 O + , NH 4 + , Ag + , or K + ) were determined in water-saturated nitrobenzene. It was found that these constants increase in the cation order NH 4 + < K + < H 3 O + < Ag + < Li + < Na + .Graphical Abstract[IMAGE]
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Three photolabile analogs of substrates of methionyl-tRNA synthetase were synthesized. In one, the 4-thiouridine at the 8 position of E. coli tRNAfMet was alkylated with [14C]p-azidobromoacetanilide. In the second, [14C]p-azidobenzoic acid hydrazide was condensed with the 3'-terminal dialdehyde of periodate-oxidized Escherichia coli tRNAfMet. The modified tRNAs could be purified by chromatography on benzoylated DEAE-cellulose. The third photolabile compound was [3H]methioninyl-8-azido-adenosine 5'-phosphate, an analog of the methionyl adenylate intermediate in the aminoacylation reaction. Irradiation of each of these compounds in the presence of equimolar amounts of E. coli methionyl-tRNA synthetase of micrometer concentrations gave 5-15% crosslinking.
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eng_Latn
| 31,400 |
Dimethyldioxirane epoxidation of benzofurans: reversible thermal and photochemical valence isomerization between benzofuran epoxides, quinone methides, and benzoxetenes
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Low-temperature oxidation of the four possible regioisomeric methoxy-substituted benzofurans 1 by dimethyldioxirane afforded the rather labile epoxides 2, which are in equilibrium with their equally labile quinone methides 3 through reversible valence isomerization. Photochemical cyclization of the latter afforded the hitherto unknown benzoxetenes 4, which are sufficiently persistent at subambient temperatures to permit spectral characterization. The labile oxetenes 4 slowly revert to the same equilibrium mixtures of the epoxides 2 and quinone methides 3 as are obtained in the dioxirane epoxidation of the benzofurans 1
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1. The syntheses and properties of 7-acetoxymethylbenz[a]anthracene 5,6-oxide, 7-hydroxymethylbenz[a]anthracene 5,6-oxide and trans-5,6-dihydro-5,6-dihydroxy-7-hydroxymethylbenz[a]anthracene are described.2. 7-Hydroxymethylbenz[a]anthracene 5,6-oxide was converted by rat-liver microsomal preparations and homogenates into trans-5,6-dihydro-5,6-dihydroxy-7-hydroxymethylbenz[a]anthracene and by rat-liver soluble fraction and glutathione, or by rat-liver homogenates, into a glutathione conjugate. Small amounts of 5-hydroxy-7-hydroxymethylbenz[a]anthracene were sometimes formed in these incubations, probably by a non-enzymic reaction.3. 7-Hydroxymethylbenz[a]anthracene was metabolized by rat liver microsomes into a number of products including the trans-5,6-dihydrodiol. This product was not detected when the hydroxymethyl derivative was incubated with rat liver homogenate.4. 7-Hydroxymethylbenz[a]anthracene 5,6-oxide was less efficient in alkylating 4-(p-nitrobenzyl)pyridine than 7-methylbenz[a]anthracene 5,6-...
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eng_Latn
| 31,401 |
Electrochemical lithium doping of a pentacene molecule semiconductor
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Li-doped pentacene has been developed by using an electrochemical approach; that is, constant-potential electrolysis. Li-doped pentacene was characterized by Raman spectrometry and x-ray diffraction measurements. Lithium doping introduces a modification of the C–H vibrational modes located at the end of pentacene molecules. A low doping level has been observed for electrochemical synthesis of Li-doped pentacene, and lithium species are supposed to be intercalated between the two-dimensional pentacene layers. The lithium-doped pentacene exhibits a conductivity of ∼6×10−3Scm−1.
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The present invention is directed to phosphatidylinositol or lysophosphatidylinositol concentration indicators relates to efficacy evaluation method of a medicament having a therapeutic or prophylactic effect for a disease EL activity is associated. Further, the present invention relates to a kit for use in screening methods and method of the EL active inhibitors using phosphatidylinositol.
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eng_Latn
| 31,402 |
Medicinal gold compounds form tight adducts with the copper chaperone Atox-1: biological and pharmacological implications
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Based on ESI-MS measurements, we show here that some representative cytotoxic gold(III) compounds produce stable adducts upon reaction with the copper chaperone Atox-1; notably, such adducts contain gold in the oxidation state +1. These findings are of interest to understand the intracellular metabolism of medicinal gold species and to develop new potent inhibitors of the copper trafficking system.
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Abstract Five hypoeutectoid CuGa alloys that undergo a massive transformation on cooling have been investigated by electron microscopy. It is shown that in addition to dislocations and stacking faults the massive phases contain areas of highly striated regions and that these regions may consist of a duplex structure involving f.c.c. and h.c.p. phases. The possibility that this structure is produced by growth or by a martensitic mechanism is discussed. Some details are given also of the f.c.c. structure that is produced by deformation and annealing of of the equilibrium h.c.p. phase.
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eng_Latn
| 31,403 |
Stereoselective reduction of aromatic ketones by a new ketoreductase from Pichia glucozyma
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A new NADPH-dependent benzil reductase (KRED1-Pglu) was identified from the genome of the non-conventional yeast Pichia glucozyma CBS 5766 and overexpressed in E. coli. The new protein was characterised and reaction parameters were optimised for the enantioselective reduction of benzil to (S)-benzoin. A thorough study of the substrate range of KRED1-Pglu was conducted; in contrast to most other known ketoreductases, KRED1-Pglu prefers space-demanding substrates, which are often converted with high stereoselectivity. A molecular modelling study was carried out for understanding the structural determinants involved in the stereorecognition experimentally observed and unpredictable on the basis of steric properties of the substrates. As a result, a new useful catalyst was identified, enabling the enantioselective preparation of different aromatic alcohols and hydroxyketones.
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1. ::: ::: The kinetics of the phototransformation of sterically hindered phenol inorganic solvents was investigated. The singlet state is the photochemically active state. The phenol is consumed according to a first-order law. The quantum yields of the phototransformation for the investigated phenol in various solvents amount to ∼ 10−2−10−3. ::: ::: ::: ::: ::: 2. ::: ::: It was found that the phototransformation of phenol is accelerated in alcohols, and this was explained by chemical reaction of the singlet excited molecules of the phenol with oxygen. ::: ::: ::: ::: ::: 3. ::: ::: In a frozen (77°K) solution the phototransformation of sterically hindered phenol occurs by a two-quantum mechanism.
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eng_Latn
| 31,404 |
[Determination of chlorhexidine acetate in disinfectant by high performance liquid chromatography].
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A high performance liquid chromatography(HPLC) was described for the determination of chlorhexidine acetate in disinfectant on a C18 column using acetonitrile-0.02 mol/L potassium dihydrogen phosphate solution(pH2.5) (40:60) as mobile phase. The regression equation was linear when the chlorhexidine acetate concentration was lower than 1.00 g/L. The detection limit was 8 mg/L. The precision was less than 4.0% and the recovery varied from 99.8% to 115.2%. The method was more sensitive, rapid and simple than other HPLC methods, and the characteristic of low disturbance makes it especially important for the assay of chlorhexidine acetate in compound disinfectant comparing with titrimetry and UV spectrophotometry.
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Abstract Palladium catalysts supported on Cs 2.5 H 0.5 PW 12 O 40 -incorporated MCF silica (Pd/CsPW-MCF- X ( X = 14.3, 21.8, 28.1, 33.4, and 38.0)) were prepared with a variation of Cs 2.5 H 0.5 PW 12 O 40 content ( X , wt.%). The prepared catalysts were then applied to the direct synthesis of hydrogen peroxide from hydrogen and oxygen. Selectivity for hydrogen peroxide and yield for hydrogen peroxide over Pd/CsPW-MCF- X catalysts showed volcano-shaped curves with respect to Cs 2.5 H 0.5 PW 12 O 40 content. Acidity of the catalysts also showed a volcano-shaped trend with respect to Cs 2.5 H 0.5 PW 12 O 40 content. It was revealed that yield for hydrogen peroxide increased with increasing acidity of Pd/CsPW-MCF- X catalyst. Pd/CsPW-MCF- X efficiently served as an alternate acid source and as an active metal catalyst in the direct synthesis of hydrogen peroxide from hydrogen and oxygen.
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eng_Latn
| 31,405 |
The influence of L-4-oxalysine on carbon tetrachloride-induced changes in drug-metabolizing enzyme activity of mouse liver.
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1. Carbon tetrachloride (0.2 ml/kg) and L-4-oxalysine (200 mg/kg per day for two days) were administered to male mice separately, and together, and the liver drug-metabolizing parameters measured. 2. Carbon tetrachloride alone depleted hepatic microsomal protein content by 50% and cytosolic sulphydryl compounds by 90%; oxalysine alone had no effect. 3. Microsomal cytochrome P-450 was decreased by 60%, cytochrome b5 by 30%, ethylmorphine N-demethylation by 50% and 7-ethyoxycoumarin O-deethylation by 80% following carbon tetrachloride administration; oxalysine had no effect on these losses. 4. After administration of carbon tetrachloride, cytosolic glutathione S-transferase activity was decreased by 16%; this effect was not seen when oxalysine and carbon tetrachloride were given together. Oxalysine alone slightly increased this enzyme activity.
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A new combined approach of using layered double hydroxides (LDHs) for both environmental remediation and the derived material as heterogeneous catalyst for selective oxidation is presented. A series of CoAl LDHs with carbonate or nitrate anion in the interlayers was synthesized by two different methods, namely, constant-pH precipitation using NaOH as precipitating agent and homogeneous precipitation by hexamine hydrolysis. The samples were optimized for chromate removal and an uptake of 45 mg Cr/g was obtained for CoAl2-N (CoAl-LDH with Co/Al atomic ratio of 2 and nitrate as interlayer anion by constant-pH precipitation) which was significantly higher than its corresponding carbonate sample that showed 15 mg Cr/g. The thus derived materials after uptake of chromate were explored for solvent free selective oxidation of benzyl alcohol using tert-butyl hydroperoxide as oxidant at room temperature. Among the catalysts screened, CoAl2-N sample after chromate uptake gave 23% conversion with 100% selectivity for...
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eng_Latn
| 31,406 |
Beyond the Dimer and Trimer: Tetraspiro[2.1.25.1.29.1.213.13] hexadecane‐1,3,5,7‐tetraone—the Cyclic Tetramer of Carbonylcyclopropane
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Tetraspiro[2.1.2(5).1.2(9).1.2(13).1(3)]hexadecane-1,3,5,7-tetraone 4, a unique tetraketone containing a cyclooctane core and four spiroannelated cyclopropane moieties, represents the previously unknown cyclotetramer of carbonylcyclopropane. For this purpose oxidation of the parent polyspirocyclic hydrocarbon was examined under various oxidative conditions, and the reactivity of oxidants towards methylene groups of the eight-membered cycle, activated by adjacent spirocyclopropane rings, was evaluated and contrasted. Whereas the treatment of tetraspirohexadecane with ozone resulted in monooxidation, its reaction with methyl(trifluoromethyl)dioxirane afforded the product of four-fold oxidation, triketoalcohol 10. Subsequent oxidation of the latter with Dess-Martin periodinane gave the target tetraketone 4.
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The major product channels identified in the unimolecular decompositions of C3H+6⋅C3H6 and c‐C3H+6⋅c‐C3H6 in the total energy [neutral (C3H6)2 or (c‐C3H6)2 heat of formation plus excitation energy] range of ∼230–450 kcal/mol are C3H+7+C3H5, C4H+7+C2H5, C4H+8+C2H4, and C5H+9+CH3. The measured appearance energy for C4H+7(9.54±0.04 eV) from (C3H6)2 is equal to the thermochemical threshold for the formation of C4H+7+C2H5 from (C3H6)2, indicating that the exit potential energy barrier for the ion–molecule reaction C3H+6+C3H6→C4H+7+C2H5 is negligible. There is evidence that the formations of C4H+7+C2H4+H from (C3H6)+2 and (c‐C3H6)+2 also proceed with high probabilities when they are energetically allowed. The variations of the relative abundances for C4H+7,C4H+8, and C5H+9 from (C3H6)+2 and (c‐C3H6)+2 as a function of ionizing photon energy are in qualitative agreement, suggesting that (C3H6)+2 and (c‐C3H6)+2 rearrange to similar C6H+12 isomers prior to fragmentation. The fact that C6H+11 is found to be a prima...
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eng_Latn
| 31,407 |
[(Z)‐2‐(3‐Methyl‐1,2,4‐oxadiazol‐5‐yl)‐2‐(1‐naphthyl)ethenylamino]formaldehyde oxime 1,4‐dioxane hemisolvate
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In the asymmetric unit of the title compound, C16H14N4O2·0.5C4H8O2, there are two crystallographically independent oxime molecules and one solvent molecule. Each oxime molecule has intramolecular N—H⋯O and N—H⋯N hydrogen bonds, which make the non-H atoms approximately coplanar except for the naphthyl groups. The two independent molecules are connected to each other by O—H⋯N hydrogen bonds, forming a dimer. Dimers are linked into a layer through C—H⋯O, C—H⋯N and C—H⋯π interactions. There is π-stacking of approximately parallel oxadiazole rings, with a centroid–centroid distance of 3.6234 (9) A and a dihedral angle of 8.90 (6)°. Dioxane C and H atoms are disordered over two sites each, with occupancy factors of ca 0.78:0.22.
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Thermal decomposition of hexamethyldisilane (HMDS) was studied from room temperature to 1310 K using flash pyrolysis vacuum ultraviolet single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS). Decomposition pathways of HMDS and initial reaction intermediates were also investigated using density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. Unimolecular decomposition reactions of HMDS involving Si-Si and Si-C bond cleavage, as well as decomposition producing Me4Si and Me2Si: via a three-centered elimination, were determined as the initiation reactions. Me3SiSi(Me)2∙, Me4Si, Me3Si∙ and :SiMe2 were major products of the initiation reactions. These initial products were apt to decompose by homolytic reactions. Me2Si=CH2, :SiMe2, and other silene/silylene intermediates preferred decomposing through molecular eliminations. Both homolytic and molecular elimination reactions are important in the pyrolysis of HMDS.
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eng_Latn
| 31,408 |
Finite-range DWBA calculations of the (6Li,d) reaction using an antisymmetrized 6Li wavefunction
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Abstract The ( 6 Li,d) reaction is well described by finite-range DWBA calculations that use 6 Li and deuteron optical model parameters that fit elastic scattering when an antisymmetrized 6 Li wavefunction is used.
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The cell-permeable anthracene analog diethyl-3-3'-(9,10-anthracenediyl)bis acrylate (DADB) was recently identified as a highly selective probe for singlet oxygen ((1)O(2)). Now, we show that DADB can be used to monitor (1)O(2) formation in cell culture during photodynamic therapy. An atypical property of DADB is that fluorescence emission is decreased upon oxidation. Using photosensitizers that target specific organelles, we determined that DADB could detect (1)O(2) whether formed in ER, mitochondria or lysosomes. DADB fluorescence was not, however, significantly altered when the photosensitizing agent was the palladium bacteriopheophorbide termed WST11, an agent reported to produce mainly oxygen radicals upon irradiation in an aqueous environment, whereas singlet oxygen was formed in organic solvents.
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eng_Latn
| 31,409 |
A new inorganic 2D framework based on Bi-bismuth-capping Keggin polyoxometalate with photodegradation and selective absorption of organic dyes
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A new purely inorganic 2D framework, {PMo12O40Bi2(H2O)2}·4H2O(1), was synthesized under solvothermal condition and characterized by infrared(IR) spectroscopy, thermal gravimetric analysis, UV-Vis spectroscopy, powder X-ray diffraction and single-crystal X-ray diffraction. Structural analysis reveals that compound 1 consists of Keggin unit {PMo12O40} with two bismuth atoms capping two opposite pits, leading to the bi-bismuth-capping Keggin polyoxometalate. Compound 1 not only displays excellent photodegradation activity for methyl orange(MO), but also has a high absorption capacity for rhodamine B(RhB) and methylene blue(MB). Moreover, compound 1 is extremely stable and easily separated from the reaction system for reuse.
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An analysis of results of treatment of patients with diffuse peritonitis has shown that the syndrome of polyorganic insufficiency is found in 24.2% of cases. A system of score screening assessment of severity of the course of polyorganic insufficiency syndrome has been developed. The dynamics of indicators of intoxication and oxygen metabolism was used for comparison of efficiency of hemosorption and biohemosorption. Conclusions are made that hemocarbosorption is preferable at the first phase of the syndrome of polyorganic insufficiency while biohemosorption--at the second phase of polyorganic insufficiency.
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eng_Latn
| 31,410 |
The structure and chemistry of leucodrin
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A novel oxidation procedure for cleaving glycol groups has been applied to leucodrin aryl methyl ether, to yield norleucodrinic acid aryl methyl ether. The study of derivatives of this product allows the derivation of the structure of leucodrin; the stability of the nor-derivative towards alkaline hydrogen peroxide is demonstrated. The cleavage of an intermediate α-keto-acid with periodic acid is substantiated.
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Related Article: Qing-Zhu Zeng, Jian Ouyang, Shuo Zhang, Lei Zhang|2017|Eur.J.Pharm.Sci.|102|140|doi:10.1016/j.ejps.2017.02.035
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eng_Latn
| 31,411 |
Fluorinated analogues of lipidic dialkynylcarbinol pharmacophores: synthesis and cytotoxicity in HCT116 cancer cells
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Lipidic alkynylcarbinols (LACs) have been identified as potential antitumor compounds, and a thorough understanding of their pharmacophoric environment is now required to elucidate their biological mode of action. In the dialkynylcarbinol (DAC) series, a specific study of the pharmacophore potential has been undertaken by focusing on the synthesis of three fluorinated derivatives followed by their biological evaluation. This work highlights the requirement of an electron-rich secondary carbinol center as a key structure for cytotoxicity in HCT116 cells.
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The trianion of C60 reacts readily with the ::: commonly used electrochemical solvent dichloromethane to form ::: methanofullerenes of the type ::: C60>(CH2)n, signaling a ::: cautionary warning against the use of this solvent for electrochemical ::: studies of fullerenes and opening up a new synthetic avenue for these ::: adducts.
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eng_Latn
| 31,412 |
XPS study of the nitrides, oxides and oxynitrides of titanium
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Abstract X-ray photoelectron spectroscopy is employed for the study of compositions and electronic-structure peculiarities of the powder-like titanium oxynitrides, including the compositions TiN0.96 and TiO1.03. The corresponding spectra from the core electron level and valence bands are obtained and interpreted. The conclusion is drawn that the anomalous concentration dependences of the properties of TiNTiO system solid solutions are associated with the corresponding changes of the electron-energy spectrum.
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Abstract The human promyelocytic leukemia cell line HL60 can be induced to differentiate into mature granulocytes by exposure to dimethyl sulfoxide. During differentiation a phospholipase activity, which releases arachidonic acid from membrane phospholipids, is expressed. Similarly, fatty acid cyclo-oxygenase activity increases 10-fold. In addition, there is a 40-fold increase in chemotactic formyl peptide receptor binding and a dramatic increase in glucose oxidation via the hexosemonophosphate shunt. The addition of indomethacin, a potent cyclo-oxygenase inhibitor, to the culture medium reduced the cyclo-oxygenase activity of HL60 cells exposed to dimethyl sulfoxide by 97%. However, the presence of indomethacin did not block the dimethyl sulfoxide induced increases in chemotactic formyl peptide receptor binding and hexosemonophosphate shunt activity.
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eng_Latn
| 31,413 |
Silver(I) sulfate coordination polymers with 4,4′-bipyridazine and pyridazino[4,5-d]pyridazine
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Poly[[μ4-4,4′-bipyridazine-μ5-sulfato-disilver(I)] monohydrate], {[Ag2(SO4)(C8H6N4)]·H2O}n, (I), and poly[[aqua-μ4-pyridazino[4,5-d]pyridazine-μ3-sulfato-disilver(I)] monohydrate], {[Ag2(SO4)(C6H4N4)(H2O)]·H2O}n, (II), possess three- and two-dimensional polymeric structures, respectively, supported by N-tetradentate coordination of the organic ligands [Ag—N = 2.208 (3)–2.384 (3) A] and O-pentadentate coordination of the sulfate anions [Ag—O = 2.284 (3)–2.700 (2) A]. Compound (I) is the first structurally examined complex of the new ligand 4,4′-bipyridazine; it is based upon unprecedented centrosymmetric silver–pyridazine tetramers with tetrahedral AgN2O2 and trigonal–bipyramidal AgN2O3 coordination of two independent AgI ions. Compound (II) adopts a typical dimeric silver–pyridazine motif incorporating two kinds of square-pyramidal AgN2O3 AgI ions. The structure exhibits short anion–π interactions involving noncoordinated sulfate O atoms [O⋯π = 3.041 (3) A].
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Aryl groups bound to the meso positions of porphyrins often react with neighboring groups, in particular s-acyl groups to give highly diversified monomeric and dimeric new functionalized porphyrins. The products, whose meso-aryl ring approaches coplanarity with the porphyrin macrocycle, show large shifts of UV-visible absorption bands and various potentialities for building external chelating moieties and assembling oligoporphyrins.
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eng_Latn
| 31,414 |
Trials of Class Experiments on Energy of Light Using Photocatalyst
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We performed a trial of experiments using photocatalytic reaction in advanced course in college of technology. Using titania, the following experiments were carried out ; decomposition of methylene blue solution, water droplet, fouling and mold preventions. From the results of a student questionnaire, about 90% of the students understood the theory of photocatalytic reaction, about 70-90% were interested in each experiment, and about 80% wanted to utilize the photocatalyst in their daily life. After the experiment, the students investigated the technology and products of the photocatalyst, and also discussed future applications.
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Abstract Bernthsen reaction has been carried out under microwave irradiation in the presence of p-TSA (10 mol%) as catalyst in a solventless reaction to provide 9-substituted acridines. In the present report, time economy and better yields as compared to conventional Bernthsen reaction are described.
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eng_Latn
| 31,415 |
Synthesis, antitumor evaluation and DNA photocleaving activity of novel methylthiazonaphthalimides with aminoalkyl side chains
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Abstract A series of methylthiazonaphthalimides was synthesized and quantitatively evaluated as efficient DNA intercalators, antitumor agents and DNA photocleavers. A 1 showed both efficient antitumor activities against cell lines of A549 and P388 with IC 50 of 82.8 and 31 nM, respectively. A 3 was the strongest antitumor agent against A549 with the IC 50 of 20.8 nM. A 2 , the most efficient DNA intercalator, was found to be the strongest DNA photocleaver via superoxide anion. An explanation was given for the disaccord between antitumor and DNA photocleaving activities.
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A study was carried out on the separation of active anthraquinone ingredient in Chinese rhubarb using High-Speed Countercurrent Chromatography with acid-base accommodationt. Trifluoroacetic acid (TFA) was used as the retaining acid and ammonia liquor as the eluent base. The solvent system was n-hexane-acetic ester-methanol-water (ratio by volume was 9 ∶1 ∶5 ∶5). The separative product was confirmed as five pure anthraquinone of Chinese rhubarb by High Performance Liquid Chromatography (HPLC).
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eng_Latn
| 31,416 |
Reaction of esters of N-butyl-N-isobutenylamido- and bis(N-butyl-N-isobutenylamido)phosphorus acids with oxygen and halogen-containing compounds
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1. ::: ::: Dialkyl N-butyl-N-isobutenylamidophosphites are readily oxidized by oxygen, react with methyl iodide to form the corresponding methyl phosphonates, and react with acetyl chloride to give a dialkyl chlorophosphite and N-butyl-N-isobutenylacetamide. ::: ::: ::: ::: ::: 2. ::: ::: Ethyl and triethylsilyl bis (N-butyl-N-isobutenylamido)phosphites react with carbon tetrachloride to form bis(N-butyl-N-isobutenylamido)chlorophosphate and 1,1,1-trichloropropane and trimethyltrichloromethylsilane, respectively.
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A generalized model that describes apparently “non-Nernstian” equilibrium responses of ionophore-based ion-selective electrodes (ISEs) is presented. It is formulated for primary and secondary ions of any charges that enter the membrane phase and independently form complexes with the ionophore, respectively. Equations for the phase boundary potential model were solved numerically to obtain whole response curves as a function of the sample activity of the primary ion, and analytical solutions could be obtained for apparently non-Nernstian response sections in these response curves. Ionophore-based ISEs can give three types of apparently non-Nernstian equilibrium responses, i.e., apparently “super-Nernstian”, “inverted-Nernstian”, and “sub-Nernstian” responses. The values of the response slopes depend on the charge numbers of the primary and secondary ions and on the stoichiometries of their complexes with the ionophore. The theoretical predictions for super-Nernstian responses agree well with the experiment...
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eng_Latn
| 31,417 |
Photolysis of metribuzin in oxygenated aqueous solutions
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Abstract The photochemical behaviour of metribuzin [4-amino-6-(1.1-dimethylethyl)-3-methylthio-1.2.4-triazin-5(4H)-one] and its known metabolites desaminometribuzin (DA), diketometribuzin (DK) and desaminodiketometribuzin (DADK) was investigated in aqueous oxygenated solutions at various pH values. The photochemical degradation of metribuzin over time and the formation and further fate of DA, DK and DADK were elucited. Both side-chain degradation and ring opening were detected as a result of photolysis. Six unknown metabolites as a result of side-chain degradation, including 6-azauracile, 6-azathymine and 4-aminosubstituted derivatives, were identified as very stable photodegradation products. Furthermore, some inorganic and organic ionic compounds were detected such as monocarboxylic, dicarboxylic and ketocarboxylic acids formed by side-chain degradation and ring cleavage.
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In this paper, 8 thiosemicarbazones and 12 transition metal complexes thereof have been synthesized and tested for bacteriostatic activity against five kinds of bacteria. The results show that hetero atom or substitution group in the o-position of the aryl ring to the carbonyl group in the aldehyde or ketone is essential to the bacteriostatic activity of the thiosemicarbazones, and different mechanisms of inhibition are followed by thiosemicarbazones and their complexes. The complexes displayed activity superior to the thiosemicarbazones.
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eng_Latn
| 31,418 |
Photocatalytic Overall Water Splitting on RuO2-loaded Sm3+-doped CeO2 with Heterogenous Doping Structure
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Photocatalytic overall water splitting into hydrogen and oxygen on RuO2-loaded Sm3+-doped CeO2 was examined. Pure CeO2 showed a negligible small activity, however Sm3+ doped CeO2 with heterogeneous...
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PURPOSE: To efficiently resolve a 2,2-dimethylcyclopropanecarboxylic acid. CONSTITUTION: The enantiomers of 2,2-dimethylcyclopropanecarboxylic acid are separated by salt formation with an optically active 1-(3-methoxyphenyl)- ethylamine, fractional crystallization of the diastereomeric salts and subsequent decomposition of the salts with a strong acid. COPYRIGHT: (C)1995,JPO
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eng_Latn
| 31,419 |
DFT characterization on the effect of redox-inactive cation Ca2+ on water oxidation by CoII-based cuboidal catalyst
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Abstract The activity of the biomimetic CoII-based cuboidal water oxidation catalyst (WOC) [CoII4(hmp)4(μ-OAc)2(μ2-OAc)2(H2O)] ([CoII4O4]) and its Ca2+-substitute [CoII3CaO4] were theoretically investigated to evaluate the effect of redox-inactive Ca2+ on water oxidation by CoII-based cuboidal catalyst. Compared with [CoII4O4], the smaller redox potential of [CoII3CaO4] results in the more efficient oxidation-equivalents accumulation for water oxidation. By contrast, the water oxidation by [CoII3CaO4] is identified to be more thermodynamically superior than that for [CoII4O4]. The energy barrier of key O O bond formation step in water oxidation by [CoII3CaO4] is 22.0 kcal/mol and lower than that found for [CoII4O4] (25.0 kcal/mol).
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PURPOSE: To obtain a reagent, having a short activation time and exhibiting high sensitivity to individual factors of coagulation cascade, while facilitating the handling by adding a mixture of sulfatides and solid activator, preferably kaolin. CONSTITUTION: A reagent contains a mixture of sulfatides, solid activator and a phospholipid. A short activation time when sulfatides is used for activating XII factor is not increased substantially, when sulfatides is used together with kaolin. Consequently, an operation with short incubation time, which is practical for routine inspection, can be realized using this reagent. By using an initiator for an activated thromdoplastin time (aPTT) reagent, the advantages of individual activators are combined, without combining the disadvantages thereof.
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eng_Latn
| 31,420 |
Stimuli‐Responsive Circularly Polarized Organic Ultralong Room Temperature Phosphorescence
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Purely organic room temperature phosphorescence (RTP) and ultralong RTP (OURTP) materials have attracted much attention recently, but it is challenging to integrate circularly polarized luminescence (CPL) to RTP/OURTP. Here, we show a strategy to realize CPL-active OURTP (CP-OURTP) by bonding achiral phosphor directly to the chiral center of an ester chain and this flexible chiral chain engineering enables efficient chirality transfer to carbazole aggregates, resulting in strong CP-OURTP with lifetime over 0.6 s and dissymmetry factor of 2.3×10 -3 after the conformation regulation upon photo-activation. Thus realized CP-OURTP is quite stable at room temperature but can be deactivated quickly at 50 o C to CP-RTP with high CPL stability during the photo-activation/thermal-deactivation cycles. Based on this extraordinary photo/thermal-responsive and highly reversible CP-OURTP/RTP, a CPL-featured lifetime-encrypted combinational logic device has been successfully established.
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Abstract : The objectives of this report are 1. Production of an antiserum against melanopsin, a putative circadian photoreceptor, permitting analysis of its expression pattern in mammalian retina. 2. Heterologous expression of melanopsin using recombinant baculovirus for a first characterization of its biochemical properties.
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eng_Latn
| 31,421 |
Indirect Evidence for the Biosynthesis of (1S,2S)‐1,2‐Epoxypropylphosphonic Acid as a Co‐Metabolite of Fosfomycin [(1R,2S)‐1,2‐Epoxypropylphosphonic Acid] by Streptomyces fradiae
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Treatment of the culture broth of fosfomycin (1) producing Streptomyces fradae with ammonia gives 2−3% of the C-1 epimeric compound 5, as well as the known (1R,2R)-2-amino-1-hydroxypropylphosphonic acid (3) derived from fosfomycin. The configuration of 5 was determined by capillary electrophoresis employing a quinine carbamate-type chiral selector and by synthesis from a monoprotected 1,2-dihydroxypropylphosphonate of known absolute configuration. It is postulated that (1S,2R)-2-amino-1-hydroxypropylphosphonic acid (5) is derived by ring opening of a trans-epoxide, formed as a co-metabolite of fosfomycin (cis-epoxide), with ammonia. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)
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Preparation of a series of dissociatively stable Pt(tripod)PR/sub 3/ complexes where tripod = CH/sub 3/C(CH/sub 2/PPh/sub 2/)/sub 3/ and PR/sub 3/ = PMe/sub 2/Ph, PMePh/sub 2/, PPh/sub 3/, P(4FC/sub 6/H/sub 4/)/sub 3/, P(3,5(CF/sub 3/)/sub 2/C/sub 6/H/sub 3/)/sub 3/, P(CH/sub 2/CH/sub 2/CN)/sub 3/, P(OMe)Ph/sub 2/, P(OMe)/sub 2/Ph, P(OMe)/sub 3/, P(POh)/sub 3/, and P(OCH/sub 2/CF/sub 3/)/sub 3/ are reported. /sup 195/Pt(/sup 1/H) and /sup 31/P(/sup 1/H) NMR data are also included. These data have expanded the data base available for the platinum (0) complexes and facilitated the drawing of empirical relationships from the platinum chemical shifts and platinum-phosphorus coupling constants. 29 refs., 1 fig., 1 tab.
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eng_Latn
| 31,422 |
Conformational studies of peptides derived by the enzymic hydrolysis of a gamma-type gliadin.
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The secondary structures of γ 44 gliadin and peptides derived from it by enzymic hydrolysis were studied by circular dichroism spectroscopy. Two peptides, obtained by chymotryptic cleavage, broadly corresponding to the proline-rich repetitive N-terminal domain and to the proline-poor non-repetitive C-terminal domain respectively, were studied in detail. A cryogenic solvent system, ethanediol : water (2:1 v/v), was used to determine the cd spectra of the protein and peptides at temperatures down to − 100°C. The proline-rich repetitive peptide showed a spectrum typical of βI/III reverse turns at high-temperature, but a spectrum similar to that of the poly- L -proline II helix at −100 °C. The proline-poor non-repetitive peptide, however, showed an α-helical-type cd spectrum over the temperature range studied. The results are discussed in relation to the conformations of γ-gliadins.
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Conventional methods require elevated temperatures in order to dissociate high-energy nitrogen bonds in precursor molecules such as ammonia or hydrazine used for nitride film growth. We report enhanced photodissociation of surface-absorbed hydrazine (N2H4) molecules at low temperature by using ultraviolet surface plasmons to concentrate the exciting radiation. Plasmonic nanostructured aluminum substrates were designed to provide resonant near field concentration at λ = 248 nm (5 eV), corresponding to the maximum optical cross section for hydrogen abstraction from N2H4. We employed nanoimprint lithography to fabricate 1 mm × 1 mm arrays of the resonant plasmonic structures, and ultraviolet reflectance spectroscopy confirmed resonant extinction at 248 nm. Hydrazine was cryogenically adsorbed to the plasmonic substrate in a low-pressure ambient, and 5 eV surface plasmons were resonantly excited using a pulsed KrF laser. Mass spectrometry was used to characterize the photodissociation products and indicated a...
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eng_Latn
| 31,423 |
Electrochemical and infrared spectroscopic study of the self-assembled monolayer of a cyano-bridged dimeric triruthenium complex on gold surface
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Abstract A new cyano-bridged dimeric oxo-centered triruthenium complex [{Ru 3 (μ 3 -O)(μ-CH 3 COO) 6 (py) 2 }(μ-CN){Ru 3 (μ 3 -O)(μ-CH 3 COO) 6 (py)(L py-SS )}] + (py = pyridine, L py-SS = (C 5 H 4 N–CH 2 NHC(O)(CH 2 ) 4 CH(CH 2 ) 2 SS) ([ 1 ] + ) has been prepared, characterized, and confined on an Au(1 1 1) surface to form self-assembled monolayers (SAMs) ( 1/Au ). The redox and IR spectroscopic properties observed for the discrete ions are essentially preserved in its SAMs. The molecules of SAMs 1/Au stand up with the cyano groups tilted to the gold surface. The electronic structures of 1/Au in different oxidation states have been studied by in situ infrared spectroscopy monitoring the stretching modes of the cyano group. The extent of cyano-mediated electronic communications between two triruthenium units in the SAMs has been successfully tuned by simply changing the electrolyte solutions from 0.1 M n -Bu 4 NPF 6 –CH 2 Cl 2 to aqueous 0.1 M HClO 4 .
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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
| 31,424 |
Synthesis of 5-alkylated barbituric acids and 3-alkylated indoles via microwave-assisted three-component reactions in solvent-free conditions using Hantzsch 1,4-dihydropyridines as reducing agents
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Reaction of barbituric acids with aldehydes and dihydropyridines in one pot under microwave (MW) irradiation in the absence of solvent, affords 55–82% of the 5-benzylated barbituric acids. Use of alkyl nitriles or barbituric acids with indole-3-aldehyde and dihydropyridine (DHP) afforded 3-alkylated indoles in 57–76 % yield. In each case DHPs are converted to pyridines.
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The active-site CXXC motif of thiol:disulfide oxidoreductases is essential for their catalysis of redox reactions. Changing the XX residues can perturb the reduction potential of the active-site disulfide bond of the Escherichia coli enzymes thioredoxin (Trx; CGPC) and DsbA (CPHC). The reduction potential is correlated with the acidity of the N-terminal cysteine residue of the CXXC motif. As the pKa is lowered, the disulfide bond becomes more easy to reduce. A change in pKa can account fully for a change in reduction potential in well-characterized CXXC motifs of DsbA but not of Trx. Formal analysis of the Nernst equation reveals that reduction potential contains both pH-dependent and pH-independent components. Indeed, the difference between the reduction potentials of wild-type Trx and wild-type DsbA cannot be explained solely by differences in thiol pKa values. Structural data for thiol:disulfide oxidoreductases reveal no single factor that determines the pH-independent component of the reduction potent...
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eng_Latn
| 31,425 |
Meso-meso Linked Diporphyrins from 5,10,15-Trisubstituted Porphyrins
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Meso-meso coupled diporphyrins were prepared from 5,10,15-trisubstituted zinc-porphyrins in high yields upon treatment with AgPF6 alone or with AgPF6 and I2.
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Energy minimization techniques are used in conjunction with the results of small molecule crystallographic studies on relevant compounds to propose structural models for photodamaged DNAs. Specifically, we present models both for a DNA molecule containing a psoralen photo-crosslink and for a DNA molecule containing a thymine photodimer. In both models, significant distortions of the nucleic acid helix are observed, including kinking and unwinding at the damage site and numerous changes in the backbone torsion angles relative to their standard conformations. Both the torsion angle geometries and the energetics of the models are presented in detail.
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eng_Latn
| 31,426 |
Electron Paramagnetic Resonance Studies of Photoselected Triplet Molecules. I. Phenoxazine
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Paramagnetic resonance of the phosphorescent triplet state was carried out for phenoxazine molecules in rigid glasses at 77°K. The line shapes, in Δm=2 and Δm=1 regions, depend upon the incident light polarization. With complementary results from mixed crystals of diphenylphenoxazine, it was possible to relate the principal‐axis system of the tensor describing the zero‐field splitting to the molecular‐axis system. The zero‐field energy levels of the triplet state are of the same order of magnitude as those of aromatic molecules.Selective excitation of the families of molecules corresponding to stationary values of the resonance field showed that:(1) the resonant triplet state is mainly populated via one singlet—singlet transition S1←S0,(2) the dipolar electric transition moment of this excitation is approximately parallel to the nitrogen—oxygen axis of the phenoxazine molecule.Different aspects of photoselection of magnetoselected phosphorescent molecules are discussed.
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The third of three volumes based on the 2nd Pan-Pacific Conference on Pesticide Chemistry, this book examines metabolism and residue analysis methods of environmental pesticides.
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eng_Latn
| 31,427 |
2-[(E)-(2-Chlorophenyl)iminomethyl]-6-methylphenol
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The title compound, C(14)H(12)ClNO, a Schiff base derived from 3-methyl-salicyl-aldehyde, crystallizes in the phenol-imine tautomeric form with an E conformation for the imine functionality. The mol-ecule is not planar, the dihedral angle between the aromatic rings being 36.38 (5)°. The hy-droxy H atom is involved in a strong intra-molecular O-H⋯N hydrogen bond, generating an S(6) ring.
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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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eng_Latn
| 31,428 |
Erythropoietin Reduces Post-PCI Arrhythmias in Patients With ST-elevation Myocardial Infarction
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Background: ::: Arrhythmia is the foremost cause of sudden death after myocardial infarction (MI). Animal models have recently shown that erythropoietin (EPO) can reduce the incidence of arrhythmia after MI.
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The 2,6-Bis(imino)-Pyridyl Ligands iron-based catalysts supported on SiO2 were prepared.The catalytic activity and selectivity of the system in ethylene oligomerization were studied under different supported temperature,reaction pressures,the amount of catalysts and propylene.The results showed that low supported temperature is good to catalytic activities.The activity cycle increased and polymerization temperature was stable,and ethylene conversion of unit cocatalyst methylaluminoxane(MAO) increased when using section pressure mode.But the selectivities of α-olefins almost invariant.The activities calculated by unit MAO increased after SiO2-supported.With the increase of catalysts,the ethylene conversion of unit MAO increases.The activities decrease when adding propylene and more low-molecular-weight products were produced.
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kor_Hang
| 31,429 |
The Preparation amd Reaction of Dianions Derived from M-Mquoauctl Acetamides
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Abstract During a study of varistions in the side-chain moiety of 9-phenanthry alkanolamipes of importance for the current antinalarial program, it became necesary to develop a simple method for the preparation of N-aono- alkylated propanolanines 1
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A method for the analysis of benzoic acid and salicylic acid mixtures is presented. The procedure is based upon the differential titration of the acids in dimethyl form-amide as solvent with sodium methoxide as titrant. Ointments containing the acid mixture are analyzed. Quantitative results are reported.
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eng_Latn
| 31,430 |
Structures of naphthoquinones produced by the fungus, Fusarium sp., and their biological activity toward pollen germination
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From an unidentified Fusarium sp., eight substances possessing a 1,4-naphthoquinone skeleton were isolated (F2~F9) and their structures were elucidated from the physical and chemical evidence. The effect of these compounds together with 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone and 5,8-dihydroxy-1,4-naphthoquinone on the pollen germination of Pinus thunbergii Pari was examined. 5,8-Dihydroxy-1,4-naphthoquinone showed marked inhibitory activity.
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Abstract A new luminescent compound Ni4(tpt)4(m-bdc)4·H2O (1) (tpt = tris(4-pyridyl)triazine, m-H2bdc = m-benzenedicarboxylic acid) was successfully synthesized by hydrothermal method, and characterized using single-crystal X-ray diffraction, PXRD, TG analysis and IR. 1 possesses a four-connected three-dimensional (3D) topological network with the Schlafli symbols of {65⋅8}. 1 not only has excellent thermal and chemical stability, but also is a dual-functional luminescent sensor with high selectivity and sensitivity for detection of picric acid (PA) and chromate (CrO42−) anions in water via the luminescent quenching. And the sensing mechanism for the quenching process was discussed in detail. Moreover, 1 can be regenerated by a fast and simple method in detecting PA and CrO42−, showing excellent recyclability after the sensing experiment.
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eng_Latn
| 31,431 |
Studies of molybdena-alumina catalysts: XVIII. Lanthanum-Modified supports
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Abstract A series of modified γ-alumina supports, to which 2–20% lanthanum was added, served as supports to prepare catalysts containing 6% Mo. The supports and catalysts were characterized, in the oxide and/or sulfide states, by XRD, ESCA, infrared spectroscopy, chernisorption Of CO 2 , and catalytic activity for thiophene hydrodesulfurization and hexene hydrogenation. The results showed evidence for strong interaction between the alumina and the lanthana, the latter forming a monomolecular overlayer on the alumina surface. At high La content, some La underwent sulfiding. The Mo interacted with the La-OH groups during calcination, forming essentially monolayer slabs of Mo-sulfide after sulfiding. Catalytic activities slightly decreased then increased with La loading, the latter being more pronounced for hydrogenation. Correlation of activities with NO adsorption from infrared measurements were interpretated in terms of a support effect of La on the Mo-sulfide active sites.
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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
| 31,432 |
The rhodium catalyzed three-component reaction of diazoacetates, titanium(IV) alkoxides and aldehydes
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The rhodium(II)-catalyzed three-component reaction of diazoacetates, titanium alkoxides and aldehydes is shown to give α-alkoxyl-β-hydroxyl acid derivatives; the novel C–C bond formation reaction is proposed to occur through oxonium ylides derived from diazo compounds and titanium alkoxides, and followed by intermolecular trapping by aldehydes.
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Abstract [Tc v O 2 (tn) 2 ]I (tn = trimethylenediamine) was prepared form direct reduction of TcO 4 − with dithionite in presence of the ligand. The crystal structure of [TcO 2 (tn) 2 ]I·H 2 O was determined from X-ray data. It consists on a squashed octahedron with TcO bond legnths of 1.784 and 1.754 A conforming a TcO 2 + core. The amines lie in the equatorial plane, almost perpendicular to the core. Conformational analyses of several analogous trans -M v dioxo complexes (M = Tc, Re) was performed by molecular mechanics and semiempirical calculations. Energy differences between possible conformers are low. Therefore, a mixture of different conformers is expected to be found in solution.
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eng_Latn
| 31,433 |
Controlling Co-support interaction in Co/MWCNTs catalysts and catalytic performance for hydrogen production via NH3 decomposition
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Abstract The influence of thermal treatment in hydrogen and nitrogen atmosphere of Co precursors in Co/MWCNTs system on the catalyst structure and catalytic activities in NH 3 decomposition were studied. The cobalt-support interaction in cobalt supported on MWCNTs was controlled by varying the temperature of thermal treatment of Co precursor and reaction media. Due to the interaction of cobalt species with multi wall carbon nanotubes (MWCNTs), the Co/MWCNTs catalysts after pretreatment in nitrogen exhibited higher catalytic activity for NH 3 decomposition comparing to that observed after hydrogen pretreatment of the sample. Cobalt dispersion in MWCNTs-supported catalysts was found to be a function of thermal pretreatment temperatures. The studied samples were characterized by X-ray diffraction, HRTEM, thermo gravimetric analysis, temperature programmed reduction and temperature programmed desorption
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A hypothesis that low molecular weight aromatic compounds, which occur naturally in the soil, may act as alternative substrates or inducers for the 2,4-dichlorophenoxyacetate (2,4-D) degrading enzyme system of an Arthrobacter sp. and maintain this enzyme system in the absence of 2,4-D, was examined experimentally. In a nonmanometric resting cell experiment, the 2,4-D adapted Arthrobacter sp. rapidly degraded 6 of the 12 aromatic compounds tested, and these 6 compounds were tested further with 2 additional aromatic compounds in manometric experiments with 2,4-D grown and citrate-grown cells. Homogentisic acid and catechol were oxidized more rapidly by 2,4-D grown cells than by cells grown on citrate medium. Thus, these two compounds could serve as alternative substrates for the 2,4-D degrading enzyme system of the Arthrobacter sp. In further manometric experiments, the 2,4-D degrading enzyme system in cells adapted to 2,4-dichlorophenol, catechol, or sodium benzoate was not induced.
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eng_Latn
| 31,434 |
Substitution Reactions on Iodine and Bromine: Mechanisms for Facile Halogenations of Heterocycles
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Gas-phase techniques were used to examine the halogenation of deprotonated heterocycles by perfluoroaryl and perfluoroalkyl halides. The results indicate that SN2@Br and SN2@I reactions can be very facile and are effective means of halogenating heterocycles. 2-Iodoheptafluoropropane is exceptionally selective for SN2@I reactions with yields upward of 90%. The results also provide evidence counter to the recent suggestion that t-butoxide-induced halogenations of heterocycles proceed via a radical mechanism.
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A ring-expanded bryostatin analogue was synthesized by utilizing a Ru-catalyzed tandem tetrahydropyran formation, a Pd-catalyzed tandem dihydropyran formation, and a ring-closing metathesis (RCM) as key steps. The analogue possesses potent antitumor activity against the NCI-ADR cancer cell line with an IC50 of 123 nM.
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eng_Latn
| 31,435 |
Polarity-Reversal-Catalyzed Hydrostannylation Reactions: Benzeneselenol-Mediated Homolytic Hydrostannylation of Electron-Rich Olefins
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Addition of 10 mol-% of diphenyl diselenide to hydrostannylation reactions involving electron-rich olefins results in a dramatic improvement in yield. For example, reaction of α-{[(tert-butyl)dimethylsilyl]oxy}styrene (1) with triphenylstannane (2a; 1.1 equiv.) in the presence of PhSeSePh and 2,2′-azobis[2-methylpropanenitrile] (AIBN) affords {2-{[(tert-butyl)dimethylsilyl]oxy}-2-phenylethyl}triphenylstannane (3a) in 95% yield after 2 h. This reaction presumably benefits, by the increased rate of H-atom transfer, from the in situ generated polarity-reversal catalyst, benzeneselenol.
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Abstract The production of zinc atoms in multiphoton dissociation of zinc dialkyls is probed via the resonance-enhanced multiphoton ionization technique. Asymmetric power-dependent broadening of resonant line profiles is observed. The dependence of resonant zinc ion yield is analyzed as a function of wavelength and intensity of laser field. Evidence is obtained that the dissociative production of ground state zinc atoms is suppressed with increasing laser intensity.
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eng_Latn
| 31,436 |
Modeling the Bacterial Photosynthetic Reaction Center. 2. A Combined Quantum Mechanical/Molecular Mechanical Study of the Structure of the Cofactors in the Reaction Centers of Purple Bacteria
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Ab initio and other computational studies of bacterial reaction center cofactors are usually performed using the observed (low-resolution) X-ray structures. Unfortunately, these geometries are necessarily approximate and this can have dramatic influences on calculated properties. For example, the calculated energies of the four bacteriochlorophylls in Rhodobacter sphaeroides vary by over 160 kcal mol-1. To overcome this problem, a combined quantum mechanical/molecular mechanical (QM/MM) method is employed to optimize the structure of the special pair and other cofactors in the photosynthetic reaction centers of Rhodopseudomonas viridis and Rhodobacter sphaeroides, while a purely MM model is used to refine the structure of the remaining protein environment. Specifically, the QM/MM optimizations are performed using a semiempirical AM1-based formalism. After relaxation, the energies of the bacteriochlorophylls differ by only typical conformer relative energies, ca. 5 kcal mol-1. Another example of improved c...
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Rat, mouse, rabbit, and guinea pig liver microsomes were prepared, using the calcium-aggregation method. The mean specific spectral cytochrome P450 content obtained for rat, mouse, rabbit, and guinea pig liver microsomes were 0.547, 0.394, 0.677, and 0.378 nmol cytochrome P450/mg protein, respectively. All the microsomal samples showed the ability to biotransform p-nitrophenol to p-nitrocatechol. The mean rate of formation of p-nitrocatechol by rat, mouse, rabbit, and guinea pig liver microsomes was 0.272, 0.247, 0.497 and 0.424 nmole/min/nmole cytochrome 450, respectively. This method circumvents the need of an ultracentrifuge for isolation of microsomes, by the conventional differential centrifugation method.
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eng_Latn
| 31,437 |
Epoxidation of Alkenes with O2 Catalyzed by EuCl3 under Ambient Conditions
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EuCl3 dissolved in a mixture of propanoic acid and 1,2-dichloroethane catalyzed the epoxidation of 1-hexene (81.4% selectivity, 5.34% yield for 1 h) with O2 in the presence of Zn powder at 40 °C. The epoxidation was also catalyzed by LaCl3 (0.75% yield) and SmCl3 (0.57% yield), but CeCl3 (0.08% yield) was inactive. Epoxidations of styrene and cyclohexene were also promoted by the EuCl3-catalytic system.
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Abstract Photo-excitation processes were investigated in chlorophyll solutions by irradiation with UV light sources. Photo-excited bulk effects during the bleaching experiments were diagnosed. The optical diagnostic was expressed by a Beer–Lambert matrix formulation and applied to the experimental results. The chromophores evaluated optical cross-section was 10 −15 cm 2 and the optical absorption coefficient dynamic variation was fitted to a simple reaction rate model. The bleaching rates were expressed by this model and fitted to the experimental data.
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eng_Latn
| 31,438 |
Recent Advances in Diagnosis and Treatment of Secondary Hemophagocytic Lymphohistiocytosis
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Hemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal syndrome. It is associated with uncontrolled proliferation of activated lymphocytes and macrophages which secrete great amounts of inflammatory cytokines. Despite progress in diagnosis and treatment, severe HLH still has a high mortality rate. HLH is classified as two subgroups: primary HLH and secondary HLH. Secondary HLH is involved in severe infections, malignancies and autoimmune diseases. This review seeks to update readers on current status and research progress related to this uncommon but life-threatening disease.
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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
| 31,439 |
Synthesis of 5-Formyl-2′-Deoxycytidine and its Monophosphate
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An efficient method for the synthesis of 5-formyl-2′-deoxycytidine and its monophosphate has been developed.
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The major product channels identified in the unimolecular decompositions of C3H+6⋅C3H6 and c‐C3H+6⋅c‐C3H6 in the total energy [neutral (C3H6)2 or (c‐C3H6)2 heat of formation plus excitation energy] range of ∼230–450 kcal/mol are C3H+7+C3H5, C4H+7+C2H5, C4H+8+C2H4, and C5H+9+CH3. The measured appearance energy for C4H+7(9.54±0.04 eV) from (C3H6)2 is equal to the thermochemical threshold for the formation of C4H+7+C2H5 from (C3H6)2, indicating that the exit potential energy barrier for the ion–molecule reaction C3H+6+C3H6→C4H+7+C2H5 is negligible. There is evidence that the formations of C4H+7+C2H4+H from (C3H6)+2 and (c‐C3H6)+2 also proceed with high probabilities when they are energetically allowed. The variations of the relative abundances for C4H+7,C4H+8, and C5H+9 from (C3H6)+2 and (c‐C3H6)+2 as a function of ionizing photon energy are in qualitative agreement, suggesting that (C3H6)+2 and (c‐C3H6)+2 rearrange to similar C6H+12 isomers prior to fragmentation. The fact that C6H+11 is found to be a prima...
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eng_Latn
| 31,440 |
Devise, Synthesis and Evaluation of Antimicrobial activities of Novel 8-imino Chromone Derivatives by Physicochemical Approach
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A series of novel 7-Hydroxy-3-methyl-2-phenyl-8(imino) chromone compounds 4(a-p) were prepared by reacting 8- formyl-7-hydroxy-3-methyl-2-phenyl- chromones with selected amines. The amines were so selected, which facilitate the comprehend survey of the Structure-Activity Relationships. This was accompanied with the reckoning of Lipophilicity (log P), Molar refractive index and molecular weight of the synthesized compounds. All these new compounds were characterized by 1H-NMR, 13C-NMR and Mass spectrometry. The synthesized compounds were screened for in-vitro antimicrobial activities. The Antagonist effects of the different substituent of novel compounds on the antimicrobial activity were discussed. Lead like /drug like qualities of the new compounds was devised by quantitative characterization of the compounds with their computed physicochemical properties.
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Abstract The present paper deals with a further development of the method of calculating nuclear and electron spin polarization based on the Green function formalism specifying the character of the relative motion in a pair of radical centers. In the first approximation with respect to the exchange interaction influence the calculations of the desired quantities are reduced to matrix operations. A theory of chemical polarization of electrons serves to illustrate the method. Calculations of this effect in micellar radical pairs are performed. It is shown that quantum oscillations are possible here depending on the magnitude of the external magnetic field induction.
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eng_Latn
| 31,441 |
A stereoselective synthesis of a 2-functionalized-methyl-1β-methylcarbapenem key intermediate via decarboxylation
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An efficient synthesis of a key intermediate 2a for the synthesis of 2-functionalized methyl-1β-methylcarbapenem antibiotics 1 has been realized via a stereoselective decarboxylation reaction.
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A simple, inexpensive approach is proposed for enhancing the durability of automotive proton exchange membrane fuel cells by selective promotion of the hydrogen oxidation reaction (HOR) and suppression of the oxygen reduction reaction (ORR) at the anode in startup/shutdown events. Dodecanethiol forms a self-assembled monolayer (SAM) on the surface of Pt particles, thus decreasing the number of Pt ensemble sites. Interestingly, by controlling the dodecanethiol concentration during SAM formation, the number of ensemble sites can be precisely optimized such that it is sufficient for the HOR but insufficient for the ORR. Thus, a Pt surface with an SAM of dodecanethiol clearly effects HOR-selective electrocatalysis. Clear HOR selectivity is demonstrated in unit cell tests with the actual membrane electrode assembly, as well as in an electrochemical three-electrode setup with a thin-film rotating disk electrode configuration.
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eng_Latn
| 31,442 |
The fate of 4-cyano-N, N-dimethylaniline in rats; a novel involvement of glutathione in the metabolism of anilines
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1. 4-Cyano-N, N-dimethylaniline (CDA), when administered to rats as a single oral dose (18.5 mg/kg), was rapidly absorbed and eliminated as a mixture of metabolites in the urine (86% dose after 24 h).2. Residues in tissues after 48 h, expressed as μg equiv. of CDA, were: liver, 0.35; kidney, 0.28; testes, 0-08; fat, 006; bone marrow, 0.15 and blood, 0.32.3. Absorption, metabolism and elimination following four consecutive daily doses of CDA (65 mg/kg) were similar to those at the lower dose.4. The major metabolite was 2-amino-5-cyanophenyl sulphate with its mono- and di-N-methyl analogues as minor metabolites. 4-Cyanoaniline, its N-acetyl derivative and an unstable derivative were also found as metabolites.5. Three sulphur-containing metabolites with methylsulphinyl-, methylsulphonyl-, and N-acetylcysteinyl-groups attached to the C2 atom of an N-acetyl group were identified, the latter accounting for 10.3% and 41% of the low and high doses, respectively.6. The sulphur-containing metabolites indicate the i...
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Recently, there has been an increase in research relating to the search for new optoelectronic materials for photovoltaic devices and light-emitting diodes. This research focuses on developing materials that not only possess the required optoelectronic properties (high absorption, efficient photon emission, and high charge-carrier mobilities) but are also solution-processable, which can reduce fabrication costs. Ternary ionic crystal structures, such as lead-halide perovskites, have emerged as a class of such suitable materials. However, the most promising structures, which exhibit the highest device efficiencies, rely on toxic lead as a cationic species, thereby hindering commercial application. Here, we synthesize and characterize CsCuCl3 and Cs2CuCl4 nanocrystals. These nanocrystals exhibit bright broad band green emission from copper defects when excited below 300 nm. We show that by employing a variety of ratios of coordinating solvents during synthesis, we can tailor the morphology of the nanopartic...
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eng_Latn
| 31,443 |
Unprecedented (μ-1,1-Peroxo)diferric Structure for the Ambiphilic Orange Peroxo Intermediate of the Nonheme N-Oxygenase CmlI
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The final step in the biosynthesis of the antibiotic chloramphenicol is the oxidation of an aryl-amine substrate to an aryl-nitro product catalyzed by the N-oxygenase CmlI in three two-electron steps. The CmlI active site contains a diiron cluster ligated by three histidine and four glutamate residues and activates dioxygen to perform its role in the biosynthetic pathway. It was previously shown that the active oxidant used by CmlI to facilitate this chemistry is a peroxo-diferric intermediate (CmlIP). Spectroscopic characterization demonstrated that the peroxo binding geometry of CmlIP is not consistent with the μ-1,2 mode commonly observed in nonheme diiron systems. Its geometry was tentatively assigned as μ–η2:η1 based on comparison with resonance Raman (rR) features of mixed-metal model complexes in the absence of appropriate diiron models. Here, X-ray absorption spectroscopy (XAS) and rR studies have been used to establish a refined structure for the diferric cluster of CmlIP. The rR experiments carr...
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It is both an [18]trannulene and a [60]fullerene. It is aromatic and a hexa-substituted benzene. It is formed by the first proven example of an SN 2' reaction in a fullerene. It is intensely colored and stable. It is C60 F15 [CBr(CO2 Et)2 ]3 , the first example of a new class of fullerene derivatives (see Schlegel diagram).
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eng_Latn
| 31,444 |
Proton-induced generation of remote N-heterocyclic carbene-Ru complexes.
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The proton-induced Ru-C bond variation, which was previously found to be relevant in the water oxidation, has been investigated by using cyclometalated ruthenium complexes with three phenanthroline (phen) isomers. The designed complexes, [Ru(bpy)2 (1,5-phen)](+) ([2](+)), [Ru(bpy)2 (1,6-phen)](+) ([3](+)), and [Ru(bpy)2 (1,7-phen)](+) ([4](+)) were newly synthesized and their structural and electronic properties were analyzed by various spectroscopy and theoretical protocols. Protonation of [4](+) triggered profound electronic structural change to form remote N-heterocyclic carbene (rNHC), whereas protonation of [2](+) and [3](+) did not affect their structures. It was found that changes in the electronic structure of phen beyond classical resonance forms control the rNHC behavior. The present study provides new insights into the ligand design of related ruthenium catalysts.
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We report a patient with an overlap of relapsing polychondritis and Behcet disease whose cartilaginous inflammation and genital lesions were refractory to corticosteroids and immunosuppressants, but fully remitted with the tumor necrosis factor-alpha inhibitor, infliximab. We believe this case represents the first report of a response to a tumor necrosis factor inhibitor in a patient with mouth and genital ulcerations with inflamed cartilage syndrome.
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eng_Latn
| 31,445 |
A bifunctional chiral [2]catenane based on 1,1′-binaphthyl-phosphates
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A novel [2]catenane was synthesised by ring-closing metathesis from a Ca-bisphosphate template. The resulting interlocked structure features two chiral 1,1′-binaphthyl-phosphates, leading to a bifunctional catenane structure. Initial binding studies point at the applicability of such mechanically interlocked bisphosphates as artificial receptors for dicationic guest molecules.
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Cascade reactions are an emerging technology in organic chemistry, introducing elegance and efficiency to synthetic strategies. This Review provides an overview of the novel and recent achievements in cascade processes catalyzed by bionanostructures. The examples here selected demonstrate the advances related to the application of heterogeneous nanocatalysts—nanostructures and biomolecules combined by different manner—in efficient cascade processes. Metallic nanoparticles supported on biomolecules, multienzymatic systems or bionanohybrid structures with multicatalytic activities (containing both organometallic and biocatalytic activity) were selectively and efficiently used alone or in cooperative fashion. This Review highlights examples of efficient and interesting catalytic cascade processes in organic chemistry, ultrasensitive biosensing, or energy storage and conversion, underscoring their tremendous future potential in chemical synthesis.
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eng_Latn
| 31,446 |
Optical activity in a non-enantiomorphous crystal of class \overline{4}: CdGa2S4
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Optical activity has been observed for the first time in a crystal of the non-enantiomorphous class \bar 4 CdGa2S4 is optically isotropic at 4872 A (20°C) and this allows observation of optical rotation for propagation in directions away from the c axis. The magnitude of the optical rotatory power is 17.3 deg.mm−1 along (100) and 11.6 deg.mm−1 along (110). The form of the optical rotatory power for general directions in the (001) plane has the predicted symmetry, showing positive and negative lobes. The refractive indices and birefringence are temperature-dependent and the point of isotropy shifts from 4825 A at 0°C to 5780 A at 400°C.
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The cell-permeable anthracene analog diethyl-3-3'-(9,10-anthracenediyl)bis acrylate (DADB) was recently identified as a highly selective probe for singlet oxygen ((1)O(2)). Now, we show that DADB can be used to monitor (1)O(2) formation in cell culture during photodynamic therapy. An atypical property of DADB is that fluorescence emission is decreased upon oxidation. Using photosensitizers that target specific organelles, we determined that DADB could detect (1)O(2) whether formed in ER, mitochondria or lysosomes. DADB fluorescence was not, however, significantly altered when the photosensitizing agent was the palladium bacteriopheophorbide termed WST11, an agent reported to produce mainly oxygen radicals upon irradiation in an aqueous environment, whereas singlet oxygen was formed in organic solvents.
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eng_Latn
| 31,447 |
Redifferentiation therapy of differentiated thyroid carcinoma with retinoic acid: basics and first clinical results.
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Retinoic acids (RA) regulate growth and differentiation of normal epithelial tissue. They have been employed in anticancer treatment and showed positive effects in hematopoetic and various epithelial tumors. Experimental data with follicular thyroid tumor cells showed strong evidence of induction of differentiated cell function and antiproliferative effects. Based on these data a consecutive series of 10 patients with advanced thyroid carcinoma were treated with 13-cis-retinoic acid (Roaccutan) 1.5 mg/kg body weight for six weeks. Follow-up demonstrated renewed uptake of radioiodine in 4 of 10 patients allowing performance of further radioiodine therapy. Reduction in tumor size due to antiproliferative effects of RA could not yet be verified.
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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
| 31,448 |
Organic radical-ion salts as selective electrochemical sensors
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Abstract A series of semiconducting organic radical-ion salts has been studied with regard to the potential use of such compounds in solid-state ion-selective electrodes. Improvements in working activity ranges and selectivities were obtained in comparison with previously investigated salts of TCNQ; excellent calibration graphs were obtained for lead(II), copper([I) and tctraphenylarsonium ions.
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Living in an oxygenated environment has required the evolution of effective cellular strategies to detect and detoxify metabolites of molecular oxygen known as reactive oxygen species. Here we review evidence that the appropriate and inappropriate production of oxidants, together with the ability of organisms to respond to oxidative stress, is intricately connected to ageing and life span.
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eng_Latn
| 31,449 |
Photophysics of manisyl-substituted 2-pyridin-2-yl-1,10-phenanthrolines. Dual emission dependent on structure and solvent
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Systematic variation of the substitution pattern of 2-pyridin-2-yl-1,10-phenanthrolines with 4-methoxy-2,6-dimethylphenyl (manisyl) groups α, β, and γ to the nitrogen atoms results in a 3 × 3 array of pyridyl-phenanthrolines displaying low to high quantum yields (Φf = 0.03–0.60). Photophysical studies elucidated a duality of emissive states: a weakly emissive, locally excited state, similar to the 1π,π* state of phenanthroline; and a strongly emissive, charge-transfer state, dependent on manisyl regiochemistry and solvent polarity. Ab initio calculations underscore the similarities in the electronic structures of phenanthroline and pyridyl-phenanthrolines rather than between terpyridine and pyridyl-phenanthroline.
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Aryl groups bound to the meso positions of porphyrins often react with neighboring groups, in particular s-acyl groups to give highly diversified monomeric and dimeric new functionalized porphyrins. The products, whose meso-aryl ring approaches coplanarity with the porphyrin macrocycle, show large shifts of UV-visible absorption bands and various potentialities for building external chelating moieties and assembling oligoporphyrins.
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eng_Latn
| 31,450 |
Aerobic Oxidation of Biomass-Derived 5-(Hydroxymethyl)furfural into 2,5-Diformylfuran Catalyzed by the Trimetallic Mixed Oxide (Co–Ce–Ru)
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The paper deals with oxidation of the biomass-derived model molecule 5-(hydroxymethyl)furfural (HMF) catalyzed by the trimetallic mixed oxide RuCo(OH)2CeO2. The catalyst RuCo(OH)2CeO2 was prepared through alkali hydrolysis of RuCl3, Co(NO3)2, and Ce(NO3)2 and characterized by X-ray diffraction and transmission electron microscopy techniques. RuCo(OH)2CeO2 showed high catalytic activity for aerobic oxidation of HMF under mild conditions (in the case of atmospheric oxygen pressure). Various reaction parameters such as the reaction temperature, catalyst amount, solvent, and oxidant were explored. Results demonstrated that the oxidant and solvent showed a remarkable effect on the aerobic oxidation of HMF to 2,5-diformylfuran (DFF). Under optimal conditions, DFF was obtained in a high yield of 82.6% with HMF conversion of 96.5% after 12 h at 120 °C. More importantly, the catalyst could be reused several times without significant loss of its catalytic activity.
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Objective To design and synthesis novel triazole antifungal derivatives and study the antifungal activity.Methods All the target compounds were prepared from 1,3- difluorobenzene via click reaction;The antibacterial activities of the title compounds were determined with broth dilution method.Results Twelve compounds were synthesized and characterized by 1H NMR and MS.All the title compounds exhibited potent antifungal activities against nearly all fungi tested.Conclusion The electronic effects of the substituents affected the activity of compounds,specifically the electron- donating groups.
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eng_Latn
| 31,451 |
The Compressibilities of Certain Molten Alkali Silicates and Borates
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The compressibilities of the systems Na/sub 2/O-SiO/sub 2/, K/sub 2/OSiO/ sub 2/, and Li/sub 2/O- B/sub 2/O/sub 3/ were measured. The measurements lend support to a model of the liquids containing SiO/sub 2/" iceburgs" at low M/sub 2/ O content and discrete Si or B containlng oxy-anions at high M/sub 2/O concentrations. (auth)
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This paper describes the synthesis and in vitro antimalarial activity against a P. falciparum 3D7 strain of some new 1-aryl-3-substituted propanol derivatives. Twelve of the tested compounds showed an IC50 lower than 1 μM. These compounds were also tested for cytotoxicity in murine J774 macrophages. The most active compounds were evaluated for in vivo activity against P. berghei in a 4-day suppressive test. Compound 12 inhibited more than 50% of parasite growth at a dose of 50 mg/kg/day. In addition, an FBIT test was performed to measure the ability to inhibit ferriprotoporphyrin biocrystallization. This data indicates that 1-aryl-3-substituted propanol derivatives hold promise as a new therapeutic option for the treatment of malaria.
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eng_Latn
| 31,452 |
HRRP-ATR Method Utilizing Polarization Information
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A voting HRRP-ATR scheme based on fully polarization information is presented in this paper.Ex perimented results show that the proposed approach outperforms the single polar-ization based method.
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The FTIR spectra of uracil and thymine were studied at different concentrations in pure Ar matrices as well as in H2O or HCl doped Ar matrices. The spectral results suggest the presence of open dimers in associated uracil and thymine. The structure of heterodimers of uracils with H2O and HCl is discussed.
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eng_Latn
| 31,453 |
The reaction of 2,4-diethoxycarbonyl-5-hydroxy-5-methyl-3-phenylcyclohexanone with 2,4-dinitrophenylhydrazine
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The reactions of one racemate of 2,4-diethoxycarbonyl-5-hydroxy-5-methyl-3-phenylcyclohexanone with 2,4-dinitrophenylhydrazine have been reinvestigated.
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The major product channels identified in the unimolecular decompositions of C3H+6⋅C3H6 and c‐C3H+6⋅c‐C3H6 in the total energy [neutral (C3H6)2 or (c‐C3H6)2 heat of formation plus excitation energy] range of ∼230–450 kcal/mol are C3H+7+C3H5, C4H+7+C2H5, C4H+8+C2H4, and C5H+9+CH3. The measured appearance energy for C4H+7(9.54±0.04 eV) from (C3H6)2 is equal to the thermochemical threshold for the formation of C4H+7+C2H5 from (C3H6)2, indicating that the exit potential energy barrier for the ion–molecule reaction C3H+6+C3H6→C4H+7+C2H5 is negligible. There is evidence that the formations of C4H+7+C2H4+H from (C3H6)+2 and (c‐C3H6)+2 also proceed with high probabilities when they are energetically allowed. The variations of the relative abundances for C4H+7,C4H+8, and C5H+9 from (C3H6)+2 and (c‐C3H6)+2 as a function of ionizing photon energy are in qualitative agreement, suggesting that (C3H6)+2 and (c‐C3H6)+2 rearrange to similar C6H+12 isomers prior to fragmentation. The fact that C6H+11 is found to be a prima...
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eng_Latn
| 31,454 |
Clinical significance of combined detection of three indicators on type 2 diabetes mellitus patients with coronary heart disease
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Objective To investigate the clinical value of hemoglobin A1c(HbA1C),high sensitivity C-reactive protein(hs-CRP) and D-Dimer levels in type 2 diabetes mellitus(T2DM)patients with coronary heart disease.Methods HbA1C,hs-CRP and D-dimer levels were measured in T2DM patients with CHD(n=61),T2DM patients without CHD(n=82) as well as 85 healthy people.Results The levels of HbA1C,hs-CRP and D-Dimer gradually increased in healthy control group,T2DM patient group and T2DM with CHD patient group(P0.01,P0.05),and there were positive relations among HbA1C,hs-CRP and D-dimer in T2DM and T2DM with CHD patient groups(P0.05).Conclusion Integrated detection of HbA1C,hs-CRP and D-dimer levels are associated with T2DM patients with coronary heart disease.Monitoring those levels might be helpful for the surveillance and outcome prediction.
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Abstract A summary of recent developments in the study of the reactions of tertiary amines with triosmium cluster complexes is presented. The relationships between iminium ion ligands, dimethylaminocarbene ligands and dimethylaminocarbyne ligands in several series of triosmium carbonyl cluster complexes are described. The transformations are dominated by binuclear CH activation processes. Novel ligand coordination modes were characterized by crystallographic methods.
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eng_Latn
| 31,455 |
A Review of H2CO 6cm Masers in the Galaxy
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We present a review of the field of formaldehyde (H 2 CO) 6cm masers in the Galaxy. Previous to our ongoing work, H 2 CO 6cm masers had been detected in the Galaxy only toward three regions: NGC7538 IRS1, Sgr B2, and G29.96–0.02. Current efforts by our group using the Very Large Array, Arecibo, and the Green Bank Telescope have resulted in the detection of four new H 2 CO 6cm maser regions. We discuss the characteristics of the known H 2 CO masers and the association of H 2 CO 6cm masers with very young regions of massive star formation. We also review the current ideas on the pumping mechanism for H 2 CO 6cm masers.
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The mechanochemical technique of ball milling has been applied to the asymmetric opening of meso-anhydrides, mediated by the cinchona alkaloid quinidine. A simple workup procedure affords the products, optically active dicarboxylic acid monoesters, in high yields, with up to 64% ee. With most substrates no column chromatography was needed. A range of various alcohols, as well as anhydrides, reacted well thus demonstrating the scope of this methodology. Even mixtures of purely solid components react, and no solvent is required (except during the workup). The possible use of almost equimolar amounts of starting materials significantly simplifies the product isolation compared to the standard solution reaction.
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eng_Latn
| 31,456 |
Chemoselective Activation of Aldimine in Preference to Aldehyde by the Combination of BF3•OEt2 and Water: Novel Catalyst for the Mannich-type Reaction
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Reported herein are that catalytic amount of conventional Lewis acids activated aldimines in preference to aldehydes, and addition of water to BF3•OEt2 accelerated the Mannich-type reaction significantly to afford β-amino carbonyl compounds in high yields.
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Bismuth donors ion-implanted in $^{28}$Si and $^\text{nat}$Si are studied using magnetic resonance spectroscopy based on spin dependent recombination. The hyperfine clock transition, at which the linewidth is significantly narrowed, is observed for the bismuth donors. The experimental results are modeled quantitatively by molecular orbital theory for a coupled pair consisting of a bismuth donor and a spin dependent recombination readout center, including the effect of hyperfine and Zeeman interactions.
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eng_Latn
| 31,457 |
Ask the experts: future of the pharmaceutical industry. Interview by Future Medicinal Chemistry.
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The pharmaceutical industry is facing numerous, well-documented challenges - from the effects of patent expirations to high attrition rates in the drug-development pipeline. Future Medicinal Chemistry has invited a group of leaders from academia and industry to express their views on where the industry is heading and speculate as to what role medicinal chemists will play in the future.
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Abstract Measurements of the atomic hydrogen fluorescence (Lyα) yield important information on the dissociation behavior of molecular hydrogen under photon impact. Under certain assumptions the dissociation cross section of the molecule can be deduced from such experiments. By applying an appropriate electric field in the observation region those dissociations leading to the formation of metastable hydrogen atoms can be quantitatively determined. This information opens the possibility to describe the predissociation of the excited H2-molecules in the C-, D-and B″-states. The experiments show that the excited molecules in these particular states dissociate into H(1S) and H(2S) by configuration interaction with the B′-state.
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eng_Latn
| 31,458 |
Protection against peroxynitrite reactions by flavonoids.
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Peroxynitrite is believed to contribute to pathogenesis of various diseases. Search for drugs and nutraceuticals able to limit peroxynitrite reactions is thus of interest. This study aimed to compare the capacity of 16 flavonoids and several other compounds present in food to prevent peroxynitrite reactions in three different test systems, based on fluorescein bleaching, tyrosine nitration and serum albumin thiol oxidation. The sequence of protective capacity of the antioxidants was different in various systems. Correlation analysis revealed that the hydroxyl group at the R'4 position of the flavonoids contributes significantly to prevention of fluorescein bleaching, R3-OH is important for prevention of thiol oxidation while R5-OH and R'3-OH are significant in prevention of tyrosine nitration. The total number of hydroxyl groups correlated with the ability of flavonoids to prevent oxidation reactions and the presence of vicinal hydroxyl groups correlated with flavonoid reactivity in all systems used.
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Abstract The salts of the new types M2[UO2F2(C2O4)], M4[UO2F2(C2O4)2] and M2[(UO2)2F4(C2O4)] (where M = potassium and rubidium) have been prepared by mixing saturated solutions of H[UO2F3]·H2O with alkali metal oxalate solutions in cold in different mole ratios. Molecular conductances of the salt solutions indicate that the ions are decomposed in dilute solution to a great extent. The complexes are also completely decomposed on passing their solutions through a column of cation exchange resin in hydrogen form. The IR spectra of the salts of [UO2F2(C2O4)]2− and [UO2F2(C2O4)2]4− indicate that oxalate is acting as a normal chelating agent, while the spectra of the salts of [(UO2)2F4(C2O4)]2− support that the ion contains bridged oxalate group. The lattice parameters of the three potassium salts have been reported.
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eng_Latn
| 31,459 |
Circulating immune complexes in renal transplant patients.
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Circulating immune complexes (CIC) were found in 12% of sera from 56 patients before renal allotransplantation. No relationship was found between the presence of CIC before transplantation and the 6 months graft survival. CIC were detected in serial blood samples obtained from 8 out of 30 patients (27%) during the first 6 weeks after transplantation. No relationship was found between CIC and acute rejection episodes. In 3 patients CIC were associated with acute infections. Thus the appearance of CIC shortly after renal transplantation may be an indicator of infection rather than rejection. CIC were detected in 32% of 50 renal transplant recipients who had functioning grafts for more than one year. No association was found between CIC and decreasing graft function, blood pressure or the recipient's original disease. CIC were frequently detected in patients with proteinuria above 3 g/24 hr suggesting a role of CIC in some cases of late renal graft failure.
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Abstract Literature sources on metal-organic materials encapsulating versatile porphyrinoids and heme enzymes have been discussed in this review. General fundamentals and structural and chemical requisites of these architectures are discussed in introduction followed by historical perspectives of the initial composites. We have categorized the structural aspects of this class of compounds according to the host and guest skeletons as well as encapsulating strategies in a sequential manner. Heme mimetic, as well as some novel applications of the materials including oxidation, electron transfer, carbene transfer and bio-molecule sensing, are then discussed and compared with each other and their homogeneous analogues based on mechanistic similarities, wherever possible.
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eng_Latn
| 31,460 |
Chemistry at High Dilution: Dinuclear 99 m Tc Complexes
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The formation of di- or polynuclear complexes at nanomolar concentrations is generally too slow to be observed with Tc-99m. It is reported in this communication that an appropriate choice of potentially bridging ligands, herein thiols HS-R, accelerates the dimerization reaction to an extent that dinuclear complexes are formed at very high dilution. The dinuclear nature of [Tc-99m(2)(mu(2)-SR)(3)(CO)(6)](-) is shown by chromatographic comparison, not only with its rhenium homologue as commonly done, but also with the true Tc-99 analogue.
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Objective To preliminarily investigate the conditions of the performance of chlorine dioxide generator for drinking water disinfection and know the overall situation of the industry.Methods From 2007 to 2008,6 companies'products were chosen for this investigation according to certain rules,and their performance indicators,such as chlorine dioxide output and conversion rate were tested by using the Five-step iodimetry method.Results On-site generating technology was commonly used,and the average conversion rate of the compound type generator was 57.06%,and the pure type generator was 84.78%.Conclusion The conversion rate of the pure type generator is better than the compound type,and the newly invented pure type generator has much better performance and lower disinfection cost.
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eng_Latn
| 31,461 |
Adsorption and Desorption of Electroactive Self-Assembled Thiolate Monolayers on Gold
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The influence of different chemical pretreatments on the formation and electrochemistry of self-assembled mixed monolayers of 11-(ferrocenylcarbonyloxy)undecanethiol and n-decanethiol was examined using cyclic voltammetry (CV) and X-ray Photoelectron Spectroscopy (XPS). The “hot-etched” pretreated surface yields mixed monolayers with higher surface coverages of the electroactive thiol than a “cold-etched” surface. It is proposed that the former surface presents a greater percentage of higher energy binding sites than the latter surface. The higher stability of these sites for the ferrocenylalkanethiolate is confirmed by desorption experiments in ethanol. The electroactive species are shown to be in dynamic adsorption/desorption equilibrium with the ethanol solution, which helps to explain a number of important properties.
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Understanding how small molecules interact with DNA is essential since it underlies a multitude of pathological conditions and therapeutic interventions. Many different intercalator compounds have been studied because of their activity as mutagens or drugs, but little is known regarding their interaction with nucleosomes, the protein-packaged form of DNA in cells. Here, using crystallographic methods and molecular dynamics simulations, we discovered that adducts formed by [(η(6) -THA)Ru(ethylenediamine)Cl][PF6 ] (THA=5,8,9,10-tetrahydroanthracene; RAED-THA-Cl[PF6 ]) in the nucleosome comprise a novel one-stranded intercalation and DNA distortion mode. Conversely, the THA group in fact remains solvent exposed and does not disrupt base stacking in RAED-THA adducts on B-form DNA. This newly observed DNA binding mode and topology dependence may actually be prevalent and should be considered when studying covalently binding intercalating compounds.
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eng_Latn
| 31,462 |
Mechanism of coal macromolecular acid doping polyaniline
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Coal was used as organic solid acid to dope PAn in this article. The temperature and pH value was measured when the reaction proceeded, and the structure of products was analyzed by FITR. We find that there are strong physical and chemical actions between coal and PAn. The polymerization mechanism is related with the coal content in Coal/PAn system. And the conductive mechanism of Coal/PAn was also suggested. The results show that Coal/PAn composite has good conductivity.
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Recent development of synthetic studies on novel marine alkaloids, haouamine A and B, is described. Haouamines have attracted considerable attention of synthetic chemists because of their unique structure and selective activity against human colon carcinoma cell line HT-29, however, only two groups have so far reported successful formation of their highly strained 3-aza-[7]-paracyclophane core. This review focuses on synthetic efforts to construct the core skeleton of haouamines reported by Baran and Wipf.
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eng_Latn
| 31,463 |
2D FT-ICR MS of Calmodulin: A Top-Down and Bottom-Up Approach
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Two-dimensional Fourier transform ion cyclotron resonance mass spectrometry (2D FT-ICR MS) allows data-independent fragmentation of all ions in a sample and correlation of fragment ions to their precursors through the modulation of precursor ion cyclotron radii prior to fragmentation. Previous results show that implementation of 2D FT-ICR MS with infrared multi-photon dissociation (IRMPD) and electron capture dissociation (ECD) has turned this method into a useful analytical tool. In this work, IRMPD tandem mass spectrometry of calmodulin (CaM) has been performed both in one-dimensional and two-dimensional FT-ICR MS using a top-down and bottom-up approach. 2D IRMPD FT-ICR MS is used to achieve extensive inter-residue bond cleavage and assignment for CaM, using its unique features for fragment identification in a less time- and sample-consuming experiment than doing the same thing using sequential MS/MS experiments.
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To the Editor: We read with interest the article by Lopez et al.1 They compared the effects of AMG 641 with calcitriol (CT) or paricalcitol (PC) alone, and the combination of the calcimimetic with either CT or PC. We have really found the paper interesting, but would like to raise some points of discussion.
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kor_Hang
| 31,464 |
Study on optical nonlinearities of porphyrin covalently functionalized single-wall carbon nanotubes
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We studied nonlinear absorption of three kinds of porphyrin covalently functionalized SWNTs using Z-scan technique with nanosecond pulses at 440 nm, 460nm, 480nm, 500nm, and 532nm. The large enhancement of nonlinear absorption in porphyrin covalently functionalized SWNTs were found at 532 nm. This nonlinear behavior of SWNTs has been shown to arise from strong nonlinear scattering, and porphyrin exhibits strong reverse saturable absorption at 532 nm. The porphyrins covalently functionalized SWNTs offer superior performance to the individual SWNTs and porphyrins by combination of nonlinear mechanism and the photoinduced electron or energy transfer between porphyrin moiety and SWNTs.
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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
| 31,465 |
Rate Enhancement of the Radical 1,2-Acyloxy Shift (Surzur-Tanner Rearrangement) by Complexation with Lewis Acids
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New prospects for synthetic applications are offered by the 1,2-acyloxy shift of β-(acyloxy)alkyl radicals, which proceeds with high yields under Lewis acidic conditions [Eq. (1)]. With the exception of cyclizations, this is the first Lewis acid mediated acceleration of a radical rearrangement.
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Removal of 137Cs+, one of the most hazardous radionuclides, from nuclear waste, is a challenging task because it requires simultaneously high capacity and high selectivity. Chalcogenides offer a great opportunity to design and create high-performance 137Cs+ absorbents. We report a new material (InSnOS) with facile ion-exchange properties. The anionic framework is based on corner-shared pseudo-T4 supertetrahedral oxysulfide [In8Sn12O10S34]16– clusters, resulting in the formula [In8Sn12O10S32]12–. The crystal structure features the interpenetration of two independent oxysulfide cluster frameworks which create pincer cavities based on sulfur atoms that prove highly effective for capturing Cs+ ions. The binding mode of the Cs+ ions by the material was determined by a single crystal structure refinement of a fully ion-exchanged single crystal. The structure determinations show that the small pores created by the two interpenetrating frameworks are the optimal size for capturing Cs+. This advantage makes the ma...
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eng_Latn
| 31,466 |
Octahedral clusters in molybdenum(II) and rhenium(III) chalcohalide chemistry
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Abstract A number of molybdenum(II) or rhenium(III) octahedral cluster compounds, mainly in chalcohalide solid state chemistry, are reported. As shown by single-crystal structure determinations, all these compounds contain (Me 6 L 8 i )L 6 a units which progressively condense when halogen ligands are substituted by chalcogen ligands according to Schafer's scheme. The physical properties are discussed in relation to the crystal structures and to electronic band structures determined by recent theoretical calculations.
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Carotenoids are widely distributed in extremophiles. Among these organisms especially C30 and C50 carotenoids are found. Here, we describe the structure and function of carotenoids in halophiles with focus on the moderately halophilic bacterium Halobacillus halophilus. H. halophilus produces an unusual C30 carotenoid. The structure was solved by HR-MS and NMR analyses as methyl glucosyl-3,4-dehydro-apo-8 -lycopenoate. Six genes could be identified that are involved in the biosynthesis of carotenoids. Together with the structural analyses of intermediates of methyl glucosyl-3,4-dehydro-apo-8 -lycopenoate produced by a pigment mutant a putative and unique biosynthesis pathway could be postulated. The isolated carotenoid and its intermediates showed a high antioxidative activity and also the protective function of these pigments could be demonstrated for H. halophilus.
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eng_Latn
| 31,467 |
Carbonyl halides of the Group VI transition metals. XIII. Diiodotetracarbonyls of molybdenum and tungsten and some of their derivatives
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Diiodotetracarbonyls of molybdenum and tungsten(II) have been prepared for the first time by the direct interaction of the parent hexacarbonyls with iodine at room temperature under the influence of ultraviolet radiation. Reaction of the iodocarbonyls with donor ligands such as triphenylphosphine, triphenylarsine, and triphenylstibine generally gives neutral substitution products, but the reaction between the molybdenum compound and triphenylphosphine yielded the previously reported triphenylphosphonium salt of the triiodotricarbonyl(triphenylphosphine)-molybdate(II) ion. Diiodotricarbonylbis(triphenylphosphine)tungsten(II) loses carbon monoxide on heating under vacuum to give the corresponding blue dicarbonyl compound. The dicarbonyl dissolved in dichloromethane readily absorbs carbon monoxide to reform the tricarbonyl and the compounds therefore represent a further carbon monoxide carrying system.
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The properties of the adenosine triphosphatase activity associated with tightly coupled, time-stable mung bean (Phaseolus aureus Roxb.) mitochondria resemble those of intact animal mitochondria. Induction of adenosine triphosphatase activity by 2,4-dinitrophenol was inhibited by oligomycin, oxidizable substrates, and high concentrations of sucrose. Upon sonication, high rates of endogenous adenosine triphosphate hydrolysis resulted, an absolute requirement for Mg(2+) was manifested, stimulation by 2,4-dinitrophenol and inhibition by sucrose were eliminated, but sensitivity to oligomycin was retained.
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eng_Latn
| 31,468 |
Fully Oriented Bilirubin Oxidase on Porphyrin-Functionalized Carbon Nanotube Electrodes for Electrocatalytic Oxygen Reduction
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The efficient immobilization and orientation of bilirubin oxidase from Myrothecium verrucaria on multi-walled carbon nanotube electrodes by using π-stacked porphyrins as a direct electron-transfer promoter is reported. By comparing the use of different types of porphyrin, the rational effect of the porphyrin structure on both the immobilization and orientation of the enzyme is demonstrated. The best performances were obtained for protoporphyrin IX, which is the natural precursor of bilirubin. These electrodes exhibit full orientation of the enzyme, as confirmed by the observable non-catalytic redox system corresponding to the T1 copper center associated with pure Nernstian electrocatalytic behavior with high catalytic currents of almost 5 mA cm−2 at neutral pH.
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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
| 31,469 |
Effect of intramolecular hydrogen-bond on the DNA-binding and photocleavage properties of polypyridyl cobalt(III) complexes
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Abstract Two polypyridyl cobalt(III) complexes containing intramolecular hydrogen-bond [Co(phen) 2 HPIP] 3+ (HPIP=2-(2-hydroxyphenyl)imidazo[4,5- f ][1,10]phenanthroline) and [Co(phen) 2 HNAIP] 3+ (HNAIP=2-(2-hydroxy-l-naphthyl)imidazo[4,5- f ][1,10]phenanthroline) have been synthesized and characterized by UV–Vis, EA and MS spectra. Binding of both complexes with calf thymus DNA has been investigated by cyclic voltammetry, absorption spectroscopy, luminescence titration, viscosity measurements and DNA cleavage assay. The results suggested that the complex [Co(phen) 2 HPIP] 3+ bound to CT DNA by intercalation via HPIP into the base pairs of DNA, while [Co(phen) 2 HNAIP] 3+ bound with DNA by partial intercalating the ligand HNAIP. In addition, both complexes have been found to promote the single-stranded cleavage of plasmid pBR 322 DNA upon irradiation, and [Co(phen) 2 HPIP] 3+ exhibited the higher cleaving efficiency.
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SummaryThe metabolism of betahistine, demethylbetahistine and 2-(2-hydroxy-ethyl) pyridine in the rabbit leads to the urinary excretion of acidic metabolities, including 2-pyridylacetate, which is excreted in part as N-2-pyridylacetylglycine. Other unidentified Koenig-positive compounds were in the acidic fraction.
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eng_Latn
| 31,470 |
Synthesis and Scavenging Hydroxyl Radical Activity of Feruloyl Piperidine Compounds
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Objective: To synthesize two feruloyl piperidine compounds,and to exploit the ability of the compounds to sca-venge hydroxyl radical(·OH).Methods:Ferulic acid and its analog were acetylated to protect phenolic hydroxyl,then reacted with piperidine,and removed the acetyl to synthesize feruloyl piperidine compounds.The ability of the target compounds to scavenge ·OH was measured by ferrosin-Fe2+ oxidation method.Results:Under the experimental condition,two feruloyl piperidine compounds showed strong activity to scavenge ·OH.Conclusion:The ·OH scavenging activity of the two compounds is as efficient as Vitamin C,and deserves further research.
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The compounds reduced are given in the table in order of increasing empirical formulas. Compounds with the same empirical formula are arranged in order of increasing number of rings in the molecule, and compounds with the same number of rings in order of increasing number of substituents. In the case of complex reaction products, the structural formula is given only for that part of the molecule in which changes took place during Birch reduction. Tetrahydrofuran used as an auxiliary solvent is denoted in the table by THF.
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eng_Latn
| 31,471 |
An efficient synthesis of fluorine-containing substituted spiro[piperidine-4,4′-pyrano[3,2-c]quinoline]-3′-carbonitrile by nonconventional methods
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Abstract A series of fluorine-containing substituted spiro[piperidine-4,4′-pyrano[3,2-c]quinolines] were synthesized through a rapid one-pot multi-component reaction under microwave irradiation and sonication. The method has the advantages of excellent yields (80–96%) and short reaction time (3–10 min). We provide a series of fluorinated quinoline derivatives interesting for biological screening tests.
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An original system combining both X-Ray Diffraction and diffuse reflectance infrared Fourier transform spectroscopy was developed with the aim to characterize Fischer-Tropsch catalysts in relevant reaction conditions. The catalytic properties of a model PtCo/silica catalyst tested with this prototype have shown to be in the same range of those obtained in similar conditions with classical fixed-bed reactors. No bulk cobalt oxidation nor sintering were observed on operando XRD patterns. The formation of linear carbonyls and adsorbed hydrocarbons species at the surface of the catalyst was observed on operando DRIFT spectra. The surface of the catalyst was also suspected to be covered with carbon species inducing unfavorable changes in selectivity.
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eng_Latn
| 31,472 |
2-Methoxy-N′-(2-methoxybenzylidene)benzohydrazide
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The title Schiff base compound, C16H16N2O3, was derived from the condensation of 2-methoxybenzaldehyde with 2-methoxybenzohydrazide in an ethanol solution. The dihedral angle between the two aromatic rings is 87.5 (3)°. In the crystal structure, the molecules are linked into chains running parallel to the a axis by intermolecular N—H⋯O hydrogen bonds.
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Thermal decomposition of hexamethyldisilane (HMDS) was studied from room temperature to 1310 K using flash pyrolysis vacuum ultraviolet single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS). Decomposition pathways of HMDS and initial reaction intermediates were also investigated using density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. Unimolecular decomposition reactions of HMDS involving Si-Si and Si-C bond cleavage, as well as decomposition producing Me4Si and Me2Si: via a three-centered elimination, were determined as the initiation reactions. Me3SiSi(Me)2∙, Me4Si, Me3Si∙ and :SiMe2 were major products of the initiation reactions. These initial products were apt to decompose by homolytic reactions. Me2Si=CH2, :SiMe2, and other silene/silylene intermediates preferred decomposing through molecular eliminations. Both homolytic and molecular elimination reactions are important in the pyrolysis of HMDS.
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deu_Latn
| 31,473 |
Stereochemistry of the hydrogen transfer to NAD catalyzed by (S)alanine dehydrogenase from Bacillus subtilis.
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The stereochemistry of the hydrogen transfer to NAD catalyzed by (S)alanine dehydrogenase [ (S)alanine: NAD oxidoreductase (EC 1.4.1.1) ] from B. subtilis was investigated. The label at C-2 of (S) [2,3--3H] alanine was enzymatically transferred to NAD, and the [4--3H]NADH produced isolated and the stereochemistry at C-4 investigated. It was found that the label was exclusively located at the (R) position which indicates that (S)alanine dehydrogenase is an A-type enzyme. This result was confirmed in an alternate way by reducing enzymatically [4--3H]NAD with non labeled (S)alanine and (S)alanine dehydrogenase and investigating the stereochemistry of the ]4--3H]NADH produced. As expected, the label was now exclusively located at the (S) position. This proves that (S)alanine dehydrogenase isolated from B. subtilis should be classified as an A-enzyme with regard to the stereochemistry of the hydrogen transfer to NAD.
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Aldehydes are widespread environmental and industrial compounds, able to stimulate a range of adverse health effects (e.g., general toxicity, allergenic reactions, mutagenicity, and carcinogenicity). We have previously presented quantitative structure-activity relationships (QSARs) for the genotoxicity of simple and alpha,beta-unsaturated aliphatic aldehydes. In this study, we show that the QSAR models are able to correctly predict--based only on the knowledge of the chemical structure--the genotoxicity of other aldehydes, not considered in the development phase of the models. This adds confidence to the reliability of our QSAR models as tools for the theoretical assessment of the genotoxic hazard posed by aldehydes. The analysis of SOS Chromotest induction ability and the ease of formation of DNA adducts by the aldehydes provided further mechanistic insights.
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eng_Latn
| 31,474 |
Hybridization of Alternating Cationic/Anionic Oligonucleotides to RNA Segments
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Abstract It is shown that oligonucleotide analogues containing alternating phosphodiester groups and cationic groups linked to phosphorus through an amidate bond hybridize to complementary RNA segments. An improved synthetic procedure for the alternating compounds is also described.
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Abstract Allylic oxidation of cycloolefins was carried out over Ag-VPO catalyst using tert-butyl hydroperoxide (TBHP) as oxidant in argon atmosphere, under our reaction conditions, attack of the activated C–H bonds was preferred instead of the epoxidation of C=C bond and corresponding α, β-enones were obtained as the main products. It is a high yielding, safe and eco-friendly method.
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eng_Latn
| 31,475 |
Transformation of arylamines into direct-acting mutagens by reaction with nitrite.
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Arylamines including aniline (I), 1-naphthylamine (II), 2-naphthylamine (III), 2-aminofluorene (IV), 1-aminoanthracene (V) and 1-aminopyrene (VI) were treated with 4 equivalent amounts of nitrite at pH3 and 37 degrees C for 4 h. The reaction mixtures of I, IV, V and VI showed mutagenicity to Salmonella typhimurium TA98 and TA100 strains without metabolic activation. The numbers of His+ revertant colonies to TA98 strain were 110/0.05 mumole I, 970/0.055 mumole IV, 620/0.10 mumole V and 870/0.02 mumole VI. These arylamines were converted into mutagens with diazoquinone, diazonium and nitro functions depending on their structures. The mutagen from I was p-diazoquinone (I2). The mutagen from IV was highly unstable fluorene-2-diazonium salt (IV1). The mutagens from V were N3O3-introduced anthracene (V1-1) and 1-nitroanthracene (V2), and those from VI were unidentified nitro-introduced compound (VI1) and 1-nitropyrene (VI2).
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Abstract Identification of surface species by IR spectroscopy is often based on common knowledge, with a clear risk of misassignment. Combining density functional theory (DFT) and IR reflection absorption spectroscopy (IRAS), we investigated surface nitrate formation on BaO/Al 2 O 3 thin films. We found that it is not possible to identify coordination geometries of nitrates based solely on their vibrational frequencies. For metal-supported thin films, however, differences in polarization of the NO stretching modes facilitate unambiguous identification. In contrast to traditional assignments, we show that both bridging and monodentate nitrates are formed on BaO, whereas on Al 2 O 3 bridging nitrates dominate.
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eng_Latn
| 31,476 |
Anesthesia in a child with homozygous porphobilinogen deaminase deficiency: a severe form of acute intermittent porphyria.
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We report a case history of the anesthetic management of a child with a severe form of acute intermittent porphyria (AIP). AIP is an autosomal dominant condition with incomplete penetrance, caused by deficiency of porphobilinogen deaminase, an enzyme found in the synthetic pathway for heme. Anesthesia and surgery may present many precipitants for a potentially fatal acute porphyric attack. These include fasting, dehydration, stress, infection and drugs. Here, we describe the safe use of sevoflurane in the maintenance of anesthesia. Its relative insolubility and low metabolism suggest that sevoflurane may be a reasonable agent for anesthesia in the porphyric patient.
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Post-synthetic exchange (PSE) and defect engineering have emerged as powerful techniques for tuning the properties and introducing novel functionality to metal organic frameworks (MOFs). Growing evidence suggests that each technique plays a key role in the mechanism of the other: linker coordination chemistry is pivotal to defective frameworks, while defect sites can help initiate PSE. Here, the intersection of these approaches is explored by exchanging an MOF with linkers already present within the framework. Post-synthetic annealing (PSA) modifies an MOF’s properties by redistributing the framework’s mixture of bound linker/modulator species. Using changes to the polymer-additive interactions in poly-1-trimethylsilyl-1-propyne nanocomposites observed through aging, we demonstrate that PSA causes one linker species to preferentially accumulate on the MOF’s crystal surface. Reaction conditions are shown to affect molecular composition of the resulting annealed UiO-66 MOFs, a finding explained through esta...
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eng_Latn
| 31,477 |
Decarboxylative Cross-Electrophile Coupling of N-Hydroxyphthalimide Esters with Aryl Iodides
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A new method for the decarboxylative coupling of alkyl N-hydroxyphthalimide esters (NHP esters) with aryl iodides is presented. In contrast to previous studies that form alkyl radicals from carboxylic acid derivatives, no photocatalyst, light, or arylmetal reagent is needed, only nickel and a reducing agent (Zn). Methyl, primary, and secondary alkyl groups can all be coupled in good yield (77% ave yield). One coupling with an acid chloride is also presented. Stoichiometric reactions of (dtbbpy)Ni(2-tolyl)I with an NHP ester show for the first time that arylnickel(II) complexes can directly react with NHP esters to form alkylated arenes.
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We attempt quantitative implementation of a previous suggestion that asymmetric charge neutralization of DNA phosphate groups may provide part of the driving force for nucleosome folding. Polyelectrolyte theory can be used to estimate the effective compressive force acting along the length of one side of the DNA surface when a fraction of the phosphate groups are neutralized by histones bound to that side. A standard engineering formula then relates the force to the bending amplitude caused by it. Calculated bending amplitudes are consistent with the curvature of nucleosomal DNA and the overall extent of charge neutralization by the histones. The relation of the model to various aspects of nucleosome folding, including the detailed path of core-particle DNA, is discussed. Several other DNA-protein complexes are listed as examples of possible asymmetric charge-induced bending.
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eng_Latn
| 31,478 |
X-Ray crystallographic characterization of the uranium–carbon σ-bond in tricyclopentadienylphenylethynyluranium(IV)
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The single-crystal X-ray diffraction study of (C5H5)3UCCPh has shown the uranium–carbon σ-bond to be significantly shorter than the uranium–η-C5H5 carbon lengths.
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AbstractThe effect of uric acid as a photoprotective agent for various solutions of FD&C Blue No. 2 was investivated. Due to the poor aqueous solubility of uric acid, solutions were made in glycerin, triethanolamine and N/5 NaOH. Uric acid in glycerin or triethanolamine was found to enhance the photostability of the dye solutions. The higher the concentration of uric acid in triethanolamine, the greater was the photoprotective action of uric acid. Increasing the amount of glycerin in solution resulted in acceleration of the rate of fading of the color presumably due to dielectric constant effect. The photoprotective action of uric acid was found to be influenced by the pH of the medium and its buffer species.
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eng_Latn
| 31,479 |
Analogs of methionyl-tRNA synthetase substrates containing photolabile groups.
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Three photolabile analogs of substrates of methionyl-tRNA synthetase were synthesized. In one, the 4-thiouridine at the 8 position of E. coli tRNAfMet was alkylated with [14C]p-azidobromoacetanilide. In the second, [14C]p-azidobenzoic acid hydrazide was condensed with the 3'-terminal dialdehyde of periodate-oxidized Escherichia coli tRNAfMet. The modified tRNAs could be purified by chromatography on benzoylated DEAE-cellulose. The third photolabile compound was [3H]methioninyl-8-azido-adenosine 5'-phosphate, an analog of the methionyl adenylate intermediate in the aminoacylation reaction. Irradiation of each of these compounds in the presence of equimolar amounts of E. coli methionyl-tRNA synthetase of micrometer concentrations gave 5-15% crosslinking.
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Preparation of a series of dissociatively stable Pt(tripod)PR/sub 3/ complexes where tripod = CH/sub 3/C(CH/sub 2/PPh/sub 2/)/sub 3/ and PR/sub 3/ = PMe/sub 2/Ph, PMePh/sub 2/, PPh/sub 3/, P(4FC/sub 6/H/sub 4/)/sub 3/, P(3,5(CF/sub 3/)/sub 2/C/sub 6/H/sub 3/)/sub 3/, P(CH/sub 2/CH/sub 2/CN)/sub 3/, P(OMe)Ph/sub 2/, P(OMe)/sub 2/Ph, P(OMe)/sub 3/, P(POh)/sub 3/, and P(OCH/sub 2/CF/sub 3/)/sub 3/ are reported. /sup 195/Pt(/sup 1/H) and /sup 31/P(/sup 1/H) NMR data are also included. These data have expanded the data base available for the platinum (0) complexes and facilitated the drawing of empirical relationships from the platinum chemical shifts and platinum-phosphorus coupling constants. 29 refs., 1 fig., 1 tab.
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eng_Latn
| 31,480 |
Efficient Gas-Sensing for Formaldehyde with 3D Hierarchical Co3O4 Derived from Co5-Based MOF Microcrystals
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Detecting formaldehyde at low operating temperature and maintaining long-term stability are of great significance. In this work, a hierarchical Co3O4 nanostructure has been fabricated by calcining Co5-based metal–organic framework (MOF) microcrystals. Co3O4-350 particles were used for efficient gas-sensing for the detecting of formaldehyde vapor at lower working temperature (170 °C), low detection limit of 10 ppm, and long-term stability (30 days), which not only is the optimal value among all reported pure Co3O4 sensing materials for the detection of formaldehyde but also is superior to that of majority of Co3O4-based composites. Such extraordinarily efficient properties might be resulted from hierarchically structures, larger surface area and unique pore structure. This strategy is further confirmed that MOFs, especially Co-clusters MOFs, could be used as precursor to synthesize 3D nanostructure metal oxide materials with high-performance, which possess high porosity and more active sites and shorter io...
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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
| 31,481 |
Chemo- and regioselective synthesis of alkyl-3-thiazoline carboxylates
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Abstract The synthesis of a series of allyl substituted 3-thiazoline-carboxylates was carried out from the corresponding thiazolidines, by a MnO 2 -mediated oxidation reaction under mild conditions. The reaction was chemoselective towards the amine–imine oxidation and was also regioselective, affording the unsaturation at the 3-position of the heterocycle.
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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
| 31,482 |
Laser-induced fluorescence of long chain molecular (C_6H_(10)O_5)_n
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The long chain molecule (C6H10O5)n is excited by 1.06?m high power picosecond laser pulse chain. The molecule absorbs two photons, and the peak wavelength of the fluorescence spectrum is at 5600 A. The polarization characteristics of the spectrum and the dependence of luminescence intensity on the excited intensity are measured.
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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
| 31,483 |
Phenyl Derivative of Iron 5,10,15-Tritolylcorrole
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The phenyl–iron complex of 5,10,15-tritolylcorrole was prepared by reaction of the starting chloro–iron complex with phenylmagnesium bromide in dichloromethane. The organometallic complex was fully characterized by a combination of spectroscopic methods, X-ray crystallography, and density functional theory (DFT) calculations. All of these techniques support the description of the electronic structure of this phenyl–iron derivative as a low-spin iron(IV) coordinated to a closed-shell corrolate trianion and to a phenyl monoanion. Complete assignments of the 1H and 13C NMR spectra of the phenyl–iron derivative and the starting chloro–iron complex were performed on the basis of the NMR spectra of the regioselectively β-substituted bromo derivatives and the DFT calculations.
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The Co(III) → Co(II) reduction reaction was studied by means of a high temperature Gouy magnetic susceptibility apparatus for the complexes: [Co(NH3)6]X3 (X Cl, Br, I, and NO3), [Co(NH3)6]2(SO4)3·2·5H2O, [Co(NH3)5H2O]X3 (X Cl, Br, I, and NO3), [Co(NH3)5X]X2 (X Cl, Br, I, and NO3), and [Co(NH3)5X]Y2 (X and Y may be Cl, Br and I). Minimum reduction temperatures were in the 100–200° temperature range with most of them in the 150–200° range. The curves for [Co(NH3)5Br]I2 and [Co(NH3)5Cl]I2 had a pronounced break at 193 and 185°, respectively. Two possible reduction mechanisms are indicated for these two complexes.
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eng_Latn
| 31,484 |
Electrocatalytic reduction of molecular oxygen using non-planar cobalt tetrakis-(4-sulfonatophenyl)-β-octabromoporphyrin
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Synthesis of a new water soluble porphyrin, cobalt(II) tetrakis-(4-sulfonatophenyl)-β-octabromoporphyrin (Br8TPPS)Co and catalytic reduction of molecular oxygen to hydrogen peroxide using this porphyrin is described. The investigated porphyrin is highly non-planar and water soluble due to the presence of eight bromides on the β-pyrrole positions and four negative charges of the sulfonatophenyl groups on the meso positions. The first reversible reduction of (Br8TPPS)CoII is diffusion controlled one-electron transfer, located at E12 = − 0.59V vs. Ag|AgCl in a pH 8.9 solution and leads to the formation of a stable [(Br8TPPS)CoI]−. The synthesized cobalt(II) porphyrin binds dioxygen and catalytically reduces it to peroxide with an over voltage for dioxygen reduction of nearly 250 mV. Cyclic and rotating ring-disc voltammetric techniques are used to examine the mechanistic aspects of the catalytic process.
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The investigations of recent progress in the fields of design and synthesis of supramolecular coordination compounds,as well as their applications,are reviewed in the text.As new potential functional materials, supramolecular coordination compounds containing thiosemicarbazide have been synthesized via molecular design and spontaneous assembly,and their composition-structure-nonlinearity relationships are discussed in this thesis.All the achievements for our research work have been carried out in order to design and synthesize new functional complex with novel structure effectively.
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eng_Latn
| 31,485 |
Design, synthesis, antinociceptive, and anti-inflammatory properties of thiazolopyrimidine derivatives
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Ten 2-(substituted benzylidene)-7-(4-chlorophenyl)-5-(furan-2-yl)-2H-thiazolo[3,2-a]pyrimidin-3(7H)-one derivatives were synthesized and evaluated. A series of heterocyclic, 2-(substituted benzylidene)-7-(4-chlorophenyl)-5-(furan-2-yl)-2H-thiazolo[3,2-a]pyrimidin-3(7H)-one were synthesized by reaction of 7-(4-chloro phenyl)-5-(furan-2-yl)-2H-thiazolo[3,2-a]pyrimidin-3(7H)-one with appropriately substituted aldehydes in the presence of anhydrous sodium acetate and glacial acetic acid. The antinociceptive activity was evaluated by tail-flick technique, anti-inflammatory activity was evaluated by carrageenan-induced paw edema test and their ulcerogenicity index was determined. The para-substituted methyl, hydroxy, fluoro, chloro, bromo, and nitro derivatives showed significant antinociceptive and anti-inflammatory activities. The detailed synthesis, spectroscopic data, and pharmacological screening of the synthesized compounds were reported.
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1. ::: ::: On the basis of obtained kinetic and thermodynamic parameters of the reaction of the reversible recombination of the 2-(4′-dimethylaminophenyl)indan-1,3-dionyl radical, it is established that the most dominating influence on the rate of this reaction is nonspecific solvation. ::: ::: ::: ::: ::: 2. ::: ::: Values of rate constants of the recombination of the 2-(4′-diphenylaminophenyl)indan-1,3-dionyl radical has a V-shaped dependence on the parameter ET, Strong solvation of this radical in chloroform converts the recombination reaction from a diffusion-controlled range to a kinetic range.
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eng_Latn
| 31,486 |
The gene coding for the α1 subunit of the skeletal dihydropyridine receptor (Cchl1a3=mdg) maps to mouse Chromosome 1 and human 1q32
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Using both chromosomal in situ hybridization and molecular techniques, we report the genetic localization of the gene coding for the alpha 1 subunit of the skeletal slow Ca2+ current channel/DHP receptor gene (Cchl1a3) on human Chromosome (Chr) 1 (1q31-1q32 region) and on mouse Chr 1 (region (F-G)). On the basis of single-strand conformation polymorphism (SSCP-PCR) analysis in an interspecific backcross, we have determined that the Cchl1a3 = mdg (muscular dysgenesis) locus is very closely linked to the myogenin (Myog) locus.
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The inhibition of methyltransferases is currently of high interest, particularly in the areas of microbial infection and cell proliferation, as there have been serious attempts to develop novel anti-microbial agents. In the present investigation, a series of 11 S-adenosyl-$L$-homocysteine analogues have been synthesized and effect of these analogues on DNA methylation catalyzed by DNA methyltransferases was studied. It was found that, while $5^{\prime}$-S-(propionic acid)$5^{\prime}$-deoxy-9-($1^{\prime}$-\beta-$D$-ribofuranosyl)1,3-dideazaadenine was an activator of EcoP15I and HhaI DNA methyltransferases, $5^{\prime}$-S-(propionic acid)$5^{\prime}$-deoxy-9-($1^{\prime}$-\beta-dribofuranosyl)adenine inhibited the methyltransferases in a non-competitive manner. An understanding of the binding of analogues to DNA methyltransferases will greatly assist the design of novel anti-microbial compounds.
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eng_Latn
| 31,487 |
Linear free energy relationships in the thiophen series. Part 2. The kinetics of the reactions of some 2-bromo-3-nitro-5-X-thiophens with substituted anilines in methanol
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The rate constants for the reactions of 2-bromo-3-nitro-5-X-thiophens (X = H, Br, CONH2, CO2Me, Ac, SO2Me, CN, or NO2) with some substituted anilines YC6H4NH2(Y =p-OMe, p-Me, H, m-Cl, or p-CO2Me) have been measured in methanol at various temperatures. The sensitivity parameters, ρ(Y) and β(X), obtained from Hammett and Bronsted correlations are practically independent of the reactivity of the starting system. The relevance of these results to the reactivity–selectivity principle is discussed.
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A ring-expanded bryostatin analogue was synthesized by utilizing a Ru-catalyzed tandem tetrahydropyran formation, a Pd-catalyzed tandem dihydropyran formation, and a ring-closing metathesis (RCM) as key steps. The analogue possesses potent antitumor activity against the NCI-ADR cancer cell line with an IC50 of 123 nM.
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eng_Latn
| 31,488 |
Towards Cellular Activation of an Artificial Metalloenzyme: Development of an Artificial Zymogen
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Regulation of enzymatic activity is essential for living organisms. Nowadays, with the emergence of synthetic biology, there is a rising interest in placing the activity of synthetic catalysts under the control of a cell. This short review aims at summarizing the regulation strategies developed to date, and at presenting the development of an artificial zymogen, which is upregulated by a natural protease. In our view, this constitutes a first step towards the cellular control of the activity of an artificial metalloenzyme.
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Features of the interaction with DNA of photoactivable aryl azides having various substituents in the aromatic ring have been studied. The nature of the interaction with DNA and the degree of its modification depend substantially on the nature of these substituents. The results obtained can be used for obtaining DNA probes bearing various marker groups.
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eng_Latn
| 31,489 |
Carotenoid hydroxylation – P450 finally!
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Cytochrome P450 monooxygenases are involved in the biosynthesis of various compounds in plants such as phenylpropanoids, lipids and phytohormones. Hydroxylation of the carotenoid e-ring is an essential reaction for the formation of lutein, the most abundant carotenoid in photosynthetic tissues. Recently, Li Tian and colleagues reported that a new P450 is responsible for this reaction. This discovery not only adds to the list of various functions of plant cytochrome P450s but also identifies one of the missing pieces of the puzzle of carotenoid biosynthesis.
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Abstract Radiation processing is an area of vigorous activity in today's India. With the indigenous expertise in Co source and irradiator technology, potentially promising applications such as sustained drug delivery systems, vulcanization of natural rubber latex (RVNRL), and degradation of polytetrafluoroethylene (PTFE) are presently investigated. Over the last four years, technologies for RVNRL and PTFE degradation have been scaled upto pilot scale operations, while radiation polymerized polymer systems have been developed for controlled release of certain drugs. With the commissioning of the 2 MeV EB machine in late 1988, a few EB based processes have also been commercially exploited. The paper briefly reviews these and presents the significant results obtained.
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eng_Latn
| 31,490 |
RESEARCH ON THE INFLUENCE OF THE NATURE OF THE LIGAND ON THE STEREOCHEMISTRY TRY OF THE NICKEL (II) AND OTHER 1ST ROW TRANSITION METAL COMPLEXES WITH SCHIFF BASES.
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Abstract : The solid and liquid state steric configurations of several bis-(N-alkylsalicylaldimino)-nickel (II) complexes were examined spectrophotometrically and by magnetic and dielectric polarization measurements. It was found that the n-propyl derivatives are planar, the t-butyl derivatives pseudo-tetrahedral, and the secalkyl derivatives either planar or pseudo-tetrahedral. Thermochemical, electronic, and steric implications are discussed. R-N-salicylaldimine-cobalt(III) complexes were found to exist in the trans-octahedral configuration only.
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Two Tn917-generated bacitracin deficient mutants of Bacillus licheniformis were isolated. Southern blot analysis of chromosomal DNA extracted from both insertional mutants showed that Tn917 inserted in the vicinity of the gene coding for the enzyme BA2 of the bacitracin synthetase enzyme complex. Measurements of bacitracin synthetase activity in cell-free extracts and positive hybridization signals in the vicinity of the BA2 gene indicate that in both bacitracin deficient mutants Tn917 could be inserted in the BA1 gene or in segments involved in regulation. Thus, it could be possible that the genes for bacitracin synthetase are clustered in the B. licheniformis genome.
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yue_Hant
| 31,491 |
Synthetic control of excited-state properties in ligand-bridged complexes of rhenium(I). Intramolecular energy transfer by an electron-transfer/energy-transfer cascade
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In the series of complexes [(4,4'-(X) 2 -2,2'-bpy)(CO) 3 Re I (4,4'-bpy)Re I (CO) 3 (4,4'-(Y) 2 -2,2'-bpy)] 2+ (X, Y=H, CH 3 , NH 2 , CO 2 Et), the ultimate site of the excited electron following metal-to-ligand charge-transfer (MLCT) excitation has been studied by transient absorbance and emission spectroscopies in polar organic solvents. The electron-donating groups NH 2 and Me increase the energy of the π* levels of the 2,2'-bpy ligand. They lead to localization of the excited electron on the bridging 4,4'-bpy ligand, as shown by the appearance of an absorption feature in CH 3 CN in transient absorbance difference spectra
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Abstract The feasibility of making analytical atomic spectrometry measurements by inductively coupled plasma-Fourier transform spectrometry (ICP-FTS) is demonstrated. Analytical working curves and detection limits are presented for Al, Ni, Fe and Ca. The effects of sample matrix composition on detection limits for analytical ICP-FTS are investigated. It is shown that a multiplex disadvantage may occur in the case of a spectral bandpass encompassing stroog emission lines of a matrix element. A “worse case” example of this problem is presented. Possible approaches to overcoming the multiplex disadvantage in analytical ICP-FTS and some ideal criteria for ICP-FTS instrumentation are presented.
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eng_Latn
| 31,492 |
The investigation of transcriptional repression mediated by ZEB2 in canine invasive micropapillary carcinoma in mammary gland
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Centro de Aquisicao e Processamento de Imagens” (CAPI- ICB/UFMG) for ::: providing the microscopes to immunofluorescence evaluations.
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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
| 31,493 |
Ligand-to-ligand charge transfer in Mo(diphos)(CO)(NO)(dtc) with diphos=1,2-bis(diphenylphosphino)ethane and dtc−=dimethyldithiocarbamate. Spectroscopy and photochemistry
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Abstract The complex Mo 0 (diphos)(CO)(NO)(dtc) with diphos=1,2-bis(diphenylphosphino)ethane and dtc − =dimethyldithiocarbamate shows a longest-wavelength absorption at λ max =520 nm which is assigned to a (dtc − → NO + ) ligand-to-ligand charge transfer (LLCT) transition. LLCT excitation leads to the release of NO and dtc which form a blue species ( λ max =690 nm). The photolysis proceeds with φ =0.018 at λ irr =546 nm.
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This paper proposes a simple duty cycle modulated direct torque control (DDTC) for permanent magnet synchronous motors (PMSMs). DDTC sequentially output an active vector and a zero vector during each control period. The duty cycle of active vector is obtained using a duty cycle generator according to the torque error, which can avoid the complex calculation process associated with conventional DDTC. Simulation and experimental results are presented to validate the effectiveness of proposed DDTC. Furthermore, the comparative evaluation of proposed DDTC and conventional DDTC is conducted to verify the superiority of proposed DDTC.
|
eng_Latn
| 31,494 |
[Protection of hepatocyte growth factor against carbon tetrachloride injury in primary rat hepatocyte culture].
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The protective effect of recombinant human hepatocyte growth factor (r-hHGF) against carbon tetrachloride (CCl4) injury in cultured rat hepatocytes was investigated. It was found that r-hHGF had cytoprotective effect on hepatocytes anainst CCl4 poisoning. Pretreatment with r-hHGF significantly increased the viability of cultured hepatocytes, reduced the leakage of intracellular alanine transaminase and potassium into the culture medium, as compared with the CCl4 group. The results suggest that r-hHGF may protect hepatocytes against CCl4 injury through lessening the severity of membrane lesion, preventing intracellular alanine transaminase and potassium leakage and sustaining the integrity of hepatocyte membrane.
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This work deals with the analysis of the performance and emissions of ethanol HCCI/PSCCI engines by means of a Dynamic Adaptive Chemistry (DAC) technique. The implementation of such a technique provides a reduction of the computational cost of the simulations without compromising the reliability of the results. Very accurate results, in terms of pressure and heat release rate profiles and CO, CO2 and UHC emissions, are obtained with ethanol as the only species for the DRGEP graph search both with the charge uniformly distributed in the combustion chamber and by directly injecting liquid fuel in the same chamber. The global speed up of DAC simulations is twice with respect to a full mechanism which consists of 57 species and 288 reactions and a further increase is expected when DAC is compared to very detailed kinetics.Copyright © 2012 by ASME
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eng_Latn
| 31,495 |
N-terminal acetylation of the nascent chains of α-crystallin
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Summary Labeling of a cell-free extract derived from eye lens tissue with ( 35 S) Met-tRNA fMet results in α-crystallin polypeptides which bear acetyl-( 35 S)methionine in N-terminal position. An attempt has been made to determine the exact moment of acetylation. For that purpose peptidyl-tRNAs were isolated in a one-step procedure which is based on a specially designed sucrose gradient referred to as strip-gradient. Separation of the nascent chains has been carried out according to their molecular weights. Our previous suggestion that N-terminal acetylation takes place while the peptide is still on the ribosome was confirmed. It is demonstrated that acetylation starts when the polypeptide chain is about 25 amino acids long and is virtually completed when the chains have reached a length of about 50 amino acids. Acetyl-CoA appears to deliver the acetyl group for the N-terminal acetylation.
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1. ::: ::: The photoelectronic spectra of the molecules of some cyclopropyl-substituted butadienes were obtained and interpreted. ::: ::: ::: ::: ::: 2. ::: ::: The processes of the formation of negative ions in dissociative capture of electrons by the molecules of these compounds were studied. The effect of the cyclopropyl groups is primarily manifested by destabilization of the molecular negative ion with respect to self-splitting of the electron.
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eng_Latn
| 31,496 |
Synthesis and Cytotoxicities of Royleanone Derivatives
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Carnosic acid was used as starting material to synthesize royleanone derivatives featured C11–C14 para quinone. The importance of C-20 group of royleanone derivatives was verified by the cytotoxicity assay of royleanonic acid, miltionone I and deoxyneocrptotanshinone. Following our synthetic route, 15 amide derivatives were synthesized and 8 compounds exhibited moderate cytotoxic activities against three human cancer lines in vitro.
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Approximate expressions for the NMR spin relaxation rate constant in the rotating frame of reference R 1ρ are derived for two-site chemical exchange by consideration of the evolution of the average density operator using the stochastic Liouville equation. R 1ρ is obtained as a linearized approximation to the largest (least negative) eigenvalue of the matrix describing the evolution of the average density operator in the long-term limit. The expressions obtained are more accurate than existing expressions when exchange is not fast and the populations of the exchanging sites are close to equal. The new expressions for R 1ρ facilitate the interpretation of chemical exchange phenomena in proteins and other biological macromolecules.
|
eng_Latn
| 31,497 |
Phosphine-catalyzed cage carbon functionalization of o-carborane: facile synthesis of alkenylcarboranes
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A phosphine-catalyzed alkenylation reaction of o-carborane with electron-deficient alkynes at the C–H vertex of the o-carborane cage has been developed, which led to the preparation of a series of 1-alkenyl-o-carboranes in moderate to very good yields with excellent regio- and stereoselectivity. This highly efficient and simple method represents the first example of organophosphine catalyzed C–H functionalization of o-carborane.
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Rat, mouse, rabbit, and guinea pig liver microsomes were prepared, using the calcium-aggregation method. The mean specific spectral cytochrome P450 content obtained for rat, mouse, rabbit, and guinea pig liver microsomes were 0.547, 0.394, 0.677, and 0.378 nmol cytochrome P450/mg protein, respectively. All the microsomal samples showed the ability to biotransform p-nitrophenol to p-nitrocatechol. The mean rate of formation of p-nitrocatechol by rat, mouse, rabbit, and guinea pig liver microsomes was 0.272, 0.247, 0.497 and 0.424 nmole/min/nmole cytochrome 450, respectively. This method circumvents the need of an ultracentrifuge for isolation of microsomes, by the conventional differential centrifugation method.
|
eng_Latn
| 31,498 |
An Improved Mass Spectrometer Ion Source
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Modifications of an electron impact ion source for a 60° mass spectrometer are described. The changes consist of (1) an almost completely enclosed ionization region which greatly reduces the contribution of ions from thermal decomposition products on the filament and reduces the contribution of background peaks and (2) a built‐in aligned and stronger magnetic field which eliminates source magnet adjustment, collimates the electron beam better and permits the use of a higher repeller voltage thereby increasing the collection efficiency for ions with initial kinetic energy. The performance of the source is described.
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Abstract Three novel molecules were designed and synthesized based on a known compound 9,10-di(naphthalen-2-yl)anthracene (MADN). To broaden the π-conjugated system, three units with different electronegativity were introduced and connected to the C-2 position of MADN by vinyl unit. The Suzuki reaction, the Wittig reaction, and the Heck reaction were employed to synthesize these compounds. MADN is a well-known anthracene derivative which has been widely used as blue emitter. All these results indicate that these novel MADN derivatives could be some kind of potential materials for OLEDs.
|
kor_Hang
| 31,499 |
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