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81.
Formation of N-phenyl substituted hydroxamic acids in the reaction of formaldehyde with substituted mtrosobenzene is strongly catalysed by Fe3+ ions, which stabilize the transition state for the rate-controlling proton transfer from the carbon of nitrosocarbinolic cation intermediate leading to the product, hydroxamic acid 相似文献
82.
Geiger CA Alekseev E Lazic B Fisch M Armbruster T Langner R Fechtelkord M Kim N Pettke T Weppner W 《Inorganic chemistry》2011,50(3):1089-1097
Recent research has shown that certain Li-oxide garnets with high mechanical, thermal, chemical, and electrochemical stability are excellent fast Li-ion conductors. However, the detailed crystal chemistry of Li-oxide garnets is not well understood, nor is the relationship between crystal chemistry and conduction behavior. An investigation was undertaken to understand the crystal chemical and structural properties, as well as the stability relations, of Li(7)La(3)Zr(2)O(12) garnet, which is the best conducting Li-oxide garnet discovered to date. Two different sintering methods produced Li-oxide garnet but with slightly different compositions and different grain sizes. The first sintering method, involving ceramic crucibles in initial synthesis steps and later sealed Pt capsules, produced single crystals up to roughly 100 μm in size. Electron microprobe and laser ablation inductively coupled plasma mass spectrometry (ICP-MS) measurements show small amounts of Al in the garnet, probably originating from the crucibles. The crystal structure of this phase was determined using X-ray single-crystal diffraction every 100 K from 100 K up to 500 K. The crystals are cubic with space group Ia3?d at all temperatures. The atomic displacement parameters and Li-site occupancies were measured. Li atoms could be located on at least two structural sites that are partially occupied, while other Li atoms in the structure appear to be delocalized. (27)Al NMR spectra show two main resonances that are interpreted as indicating that minor Al occurs on the two different Li sites. Li NMR spectra show a single narrow resonance at 1.2-1.3 ppm indicating fast Li-ion diffusion at room temperature. The chemical shift value indicates that the Li atoms spend most of their time at the tetrahedrally coordinated C (24d) site. The second synthesis method, using solely Pt crucibles during sintering, produced fine-grained Li(7)La(3)Zr(2)O(12) crystals. This material was studied by X-ray powder diffraction at different temperatures between 25 and 200 °C. This phase is tetragonal at room temperature and undergoes a phase transition to a cubic phase between 100 and 150 °C. Cubic "Li(7)La(3)Zr(2)O(12)" may be stabilized at ambient conditions relative to its slightly less conducting tetragonal modification via small amounts of Al(3+). Several crystal chemical properties appear to promote the high Li-ion conductivity in cubic Al-containing Li(7)La(3)Zr(2)O(12). They are (i) isotropic three-dimensional Li-diffusion pathways, (ii) closely spaced Li sites and Li delocalization that allow for easy and fast Li diffusion, and (iii) low occupancies at the Li sites, which may also be enhanced by the heterovalent substitution Al(3+) ? 3Li. 相似文献
83.
We introduce a generated Choquet integral with respect to absolutely monotone and sign stable set functions. Another type of integrals defined with respect to such a set function is obtained as a limit of an appropriate sequence of generated Choquet integrals. 相似文献
84.
85.
Liquid chromatography/tandem mass spectrometry for simultaneous determination of undeclared corticosteroids in cosmetic creams
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86.
Biljana Dekić Vidoslav Dekić Niko Radulović Rastko Vukićević Radosav Palić 《Chemical Papers》2010,64(3):354-359
A series of new coumarin derivatives has been synthesized by condensation of 4-chloro-3-nitrocoumarin and the appropriate
arylamine and sulfonamide in ethyl acetate in the presence of triethylamine. The synthesized compounds were screened for their
in vitro antimicrobial activity against thirteen strains of bacteria and three fungal/yeast strains using disk diffusion assays.
They were shown to possess a wide range of activities from almost completely inactive compounds to medium active ones. (4-[(5-Chloropyridin-2-yl)amino]-3-nitro-2H-chromen-2-one) showed similar activity against Klebsiella pneumoniae as tetracycline. 相似文献
87.
88.
Mike Lange Kiwon Ok Geoffrey D. Shimberg Biljana Bursac Lajos Mark Ivana Ivanovi‐Burmazovi Sarah L. J. Michel Milos R. Filipovic 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(24):8081-8085
H2S is a gaseous signaling molecule that modifies cysteine residues in proteins to form persulfides (P‐SSH). One family of proteins modified by H2S are zinc finger (ZF) proteins, which contain multiple zinc‐coordinating cysteine residues. Herein, we report the reactivity of H2S with a ZF protein called tristetraprolin (TTP). Rapid persulfidation leading to complete thiol oxidation of TTP mediated by H2S was observed by low‐temperature ESI‐MS and fluorescence spectroscopy. Persulfidation of TTP required O2 , which reacts with H2S to form superoxide, as detected by ESI‐MS, a hydroethidine fluorescence assay, and EPR spin trapping. H2S was observed to inhibit TTP function (binding to TNFα mRNA) by an in vitro fluorescence anisotropy assay and to modulate TNFα in vivo. H2S was unreactive towards TTP when the protein was bound to RNA, thus suggesting a protective effect of RNA. 相似文献
89.
Rate coefficients of the title reaction have been measured in a high‐temperature photochemistry (HTP) reactor using Ar as the bath gas. H atoms were generated by flash photolysis of NH3 and their relative concentrations were monitored by resonance fluorescence. The data are best fitted by k(295–905 K) = 6.5 × 10?34 (T/K)0.206 exp(780K T) cm6 molecule?2 s?1, with ±2σ precision values varying from 16 to 36% and corresponding suggested accuracy levels of 29–42%. Using a literature value for the relative collision efficiencies of N2 and Ar indicates that for N2 as the third body the above rate coefficient expression should be multiplied by 1.6. This leads to good agreement with two recent near 1000 K measurements. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 374–380, 2003 相似文献
90.
Doković DD Bulatović VM Bozić BD Kataranovski MV Zrakić TM Kovacević NN 《Chemical & pharmaceutical bulletin》2004,52(7):853-854
3,5-Nonadiyne, in vitro, selectively inhibits endogenous nitric oxide release (IC(50)=6.7+/-0.8 microM) by rat peritoneal macrophages at doses that do not inhibit T cell proliferation. 3,5-Nonadiyne was isolated from root essential oil of Cachrys ferulacea (L.) CALESTANI, synonym Prangos ferulacea (L.) LINDLEY, obtained by hydrodistillation and spectrometricaly identified unambiguously. 相似文献