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21.
Chemical oscillatory behavior in the uncatalyzed bromate oxidation of hydroquinone and nitrophenols is reported. The reaction is strongly inhibited by stirring. Effect of one-electron redox couples (EZ catalysts) on the system is described.
. . - ( EZ) .相似文献
22.
Ritu Pandey Sanjay Chauhan Gauri S. Singhal 《Journal of photochemistry and photobiology. B, Biology》1997,40(3):228-232
The effect of UVB irradiation on the phycobilisomes (PBSs) of Synechococcus sp. PCC 7942 cells was studied. The sucrose density-gradient-isolated PBSs from in vivo UVB-treated (280–320 nm) cells showed a strong decrease in β-phycocyanin (βPC) and -phycocyanin (PC) polypeptides. In addition to a decrease in the linker polypeptides LCM 75 (linker connecting the core to the thylakoid membranes), LR 33 (linker in the rod structure), LRC 31.5 (linker connecting the rod to the core) and LRC 29. In vitro UVB treatment of gradient-isolated intact PBSs for 1 h had no effect on any of the constituent polypeptides, and only after 2 h was a degradation of LCM 75 and LR 33 and a decrease in βPC evident. Further investigation of phycobiliproteins (4 h of UVB irradiation) using polyclonal antibody directed against purified whole PBSs revealed that, in vivo, there was a gradual decline in the levels of LCM 75, LR 33, LRC 31.5, LRC 29, βPC and PC. 相似文献
23.
The electrochemical oxidation of sulphapyridine at a pyrolytic graphite electrode was studied over a wide pH range. Sulphapyridine is oxidized in an irreversible reaction involving two electrons and two protons to give an electroactive product. On the basis of voltammetric, spectral and coulometric studies and product identification, a tentative mechanism is suggested. 相似文献
24.
Nanocrystalline zirconium carbonitride (Zr‐C‐N) and zirconium oxide (ZrO2) films were deposited by chemical vapor deposition (CVD) of zirconium‐tetrakis‐diethylamide (Zr(NEt2)4) and ‐tert‐butyloxide (Zr(OBut)4), respectively. The films were deposited on iron substrates and characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). The Zr‐C‐N films show blue, golden brown or bronze colours, with colour stability depending upon the precursor composition (pure metal amide or mixed with Et2NH). The deposition temperature showed no pronounced effect on the granular morphology of the Zr‐C‐N films. The XRD data of the films correspond to the formation of carbonitride phase whereas the XPS analyses revealed a strong surface oxidation and incorporation of oxygen in the film. The films deposited using a mixture of Zr(NEt2)4 and Et2NH showed higher N content, better adhesion and scratch resistance when compared to films obtained from the CVD of pure Zr(NEt2)4. Subject to the precursor composition and deposition temperature (550‐750 °C), the microhardness values of Zr‐C‐N films were found to be in the range 2.11‐5.65 GPa. For ZrO2 films, morphology and phase composition strongly depend on the deposition temperature. The CVD deposits obtained at 350 °C show tetragonal ZrO2 to be the only crystalline phase. Upon increasing the deposition temperature to 450 °C, a mixture of tetragonal and monoclinic modifications was formed with morphology made up of interwoven elongated grains. At higher temperatures (550 and 650 °C), pure monoclinic phase was obtained with facetted grains and developed texture. 相似文献
25.
Sanjay K Singh 《Journal of organometallic chemistry》2004,689(12):2073-2079
The synthesis and characterization of binuclear ruthenium complexes [{(η6-C6H6)Ru}2(μ-bsh)2] (1), [{(η6-C10H14)Ru}2(μ-bsh)2] (2), [{(η6-C6Me6)Ru}2(μ-bsh)2] (3), and rhodium complex [{(η5-C5Me5)RhCl}2(μ-bsh)] (4) (bsh=N,N′-bis(salicylidine)-hydrazine dianion) are reported. The complexes have been fully characterized by analytical and spectral techniques and unusual coordination mode of the ligand H2bsh has been confirmed by single crystal X-ray analysis of the complex 2. Structural data revealed extensive inter- and intra-molecular C-H?O and C-H?π interactions and involvement of methyl and isopropyl hydrogen from the p-cymene in hydrogen bonding. 相似文献
26.
Madan Mohan Harish C. Khera Shri G. Mittal Anant K. Sirivastava 《Monatshefte für Chemie / Chemical Monthly》1978,109(2):357-368
The complexes of pyridine-2-aldoxime (HPOX) and 6-methylpyridine-2-aldoxime (HMPX) with iron (II) thiocyanate of the type [Fe(L)(NCS)2] (L=HPOX and HMPX) have been prepared and characterized. A study of X-ray, magnetic, vibrational spectra (conventional and far-infrared), electronic spectra andMössbauer spectra has indicated that these complexes have polymeric, pseudo octahedral, coordination geometry with linear bridging thiocyanate ligands. The electronic spectra of mono complexes show a larger, low symmetry, ligand field than that present in [Fe(L)2(NCS)2] complexes. UnperturbedMössbauer spectra show a large quadrupole splitting, E
Q, and smaller isomer shift values in these iron (II) thiocyanate complexes. The magnetically perturbedMössbauer spectra of these iron(II) thiocyanate complexes at room temperature show that the principal component of the electric field gradient tensor is positive and corresponds to ad
xy
(5B2) ground state.With 2 Figures 相似文献
27.
A highly atom-efficient synthetic protocol for hydroarylation of terminal-aryl alkynes and styrene through the regioselective CC bond formation via the electrophilic addition of naphthols and substituted phenols has been developed using alumina-sulfuric acid as a heterogeneous supported solid acid catalyst. This methodology shows excellent regioselectivity and affords the desired product in good to excellent yield. The heterogeneous catalyst can also be recycled efficiently without much loss of activity. 相似文献
28.
The semiquinone radicals produced by one-electron reduction of 9, 10-anthraquinone, 1-amino-9, 10-anthraquinone and 1-hydroxy-9, 10-anthraquinone have been characterized in aqueous-organic mixed solvent comprising of 30.2 mol dm−3 water, 5 mol dm−3 isopropanol and 1 mol dm−3 acetone, using the pulse radiolysis technique. Spectroscopic characteristics, the kinetic parameters of formation and decay and one acid dissociation constants of the semiquinones and one-electron reduction potentials of the quinones have been estimated. The characteristics of the present semiquinone systems have been compared with those of other similar systems. The observed differences in characteristics of the semiquinones due to different substitutions have been analysed. 相似文献
29.
Vaghela SS Jethva AD Gohil MS Subbarayappa A Gour PM Susarla VS Gadde R Ghosh PK 《Annali di chimica》2003,93(9-10):841-848
A textile dye effluent containing chiefly reactive azo dyes has been treated electrochemically for discoloration and COD (chemical oxygen demand) reduction at different current densities, flow rates and dilution. Experiments have been carried out in a thin electrochemical reactor under single pass conditions using a dimensionally stable catalytic anode (DSA) and a stainless steel cathode. 相似文献
30.
Co(acac)2·2H2O efficiently catalyzes SnCl2-mediated Barbier coupling in water between carbonyls, including aromatic, aliphatic and α,β-unsaturated aldehydes, ketones, sugars and allyl bromide to afford the corresponding homoallylic alcohols in high yields. The catalyst was reused for several cycles with consistent activity. 相似文献