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981.
Yajing Yin Ping Wu Yafen Lü Pan Du Yanmao Shi Chenxin Cai 《Journal of Solid State Electrochemistry》2007,11(3):390-397
A single-walled carbon nanotube (SWNT)-modified electrode was fabricated and characterized by SEM and ac impedance techniques.
The direct electrochemistry of cytochrome c (Cyt c), which was adsorbed on the surface of the SWNT, was studied by cyclic voltammetry. The results from cyclic voltammetry and
infrared spectroscopy indicated that Cyt c remained in its original structure and did not undergo structural change after its immobilization on the SWNT. Further results
demonstrated that the SWNT had promotional effects on the direct electron transfer of Cyt c and also indicated that the immobilized Cyt c retained its electrocatalytic activity to the reduction of H2O2. This modified electrode might be used in development of new biosensors and the biofuel cells. 相似文献
982.
Emission and absorption polarization spectra as well as emission lifetimes between room temperature and 5 °K have been measured of [Cr urea6]X3 single crystals, where X stands for ClO
4
–
, J–, NO
3
–
, Br–, Cl–, F–, and X3 for JSO
4
3–
. The strong temperature dependence of the fluorescence/phosphorescence-ratios, and of the emission lifetimes is discussed. The differences between the spectra as well as the emission lifetimes of the various salts can be attributed to an anion dependent trigonal perturbation.
Die Autoren danken dem Verband der Chemischen Industrie für finanzielle Unterstützung dieser Arbeit. 相似文献
983.
Functionally substituted triorganotin halides V–IX of type R2Sn(X)(CH2)2P(O)PhR′ (R = Me, t-Bu; Rt? = OEt, t-Bu; X = Cl, Br) have been synthesized by halogen cleavage of the corresponding tetraorganotin compounds R2R2Sn(CH2)2P(O)PhR′ (R2 = Me or Ph), I–IV. The solid state structure of Me2Sn (Br) (CH2)2P(O)PhBu-t (IX), determined by X-ray diffraction, shows a distorted trigonal-bipyramidal structure at the tin atom, with intramolecular coordination of the PO group. Spectroscopic data are in agreement with such a structure in solution for compounds V–IX. Upon varying the temperature, concentration or solvent in solutions of compounds V–IX a stereoisomerization is observed. On the basis of NMR 1H, 13C, 31P, 119Sn), IR and conductivity studies, it is suggested that this stereoisomerization involves a hexacoordinated transition state at the tin atom. 相似文献
984.
Kaljurand I Kütt A Sooväli L Rodima T Mäemets V Leito I Koppel IA 《The Journal of organic chemistry》2005,70(3):1019-1028
The earlier compiled self-consistent spectrophotometric basicity scale in acetonitrile (AN) was expanded to range from 3.8 to 32.0 pK(a) units, that is 28 orders of magnitude. Altogether 54 new relative basicity measurements (DeltapK(a) measurements) were carried out and 37 new compounds were introduced to the scale (it now includes altogether 89 bases). The relative basicity of any two bases in the scale can be obtained by combining at least two independent sets of measurements. Multiple overlapping measurements make the results more reliable. The overall consistency (as defined earlier) of the measurements is s = 0.03 pK(a) units. Thorough analysis of all of our experimental data (DeltapK(a) values of this and earlier works) and experimental pK(a) data in AN available in the literature (works from the groups of Coetzee and Padmanabhan, Kolthoff and Chantooni, Jr., the Schwesinger group, Bren' et al. and some others, altogether 19 papers) was carried out. On the basis of this analysis the anchor point of the scale-pyridine-was shifted upward by 0.20 pK(a) units thereby also revising the absolute pK(a) values of all the bases on the scale. This way very good agreement between our relative data and the absolute pK(a) values of the abovementioned authors was obtained. The revised basicity scale was interconnected with the earlier published self-consistent acidity scale by DeltapK(a) measurements between acids and bases. The rms deviation between the directly measured DeltapK(a) values and the absolute pK(a) values of the compounds was 0.10 pK(a) units. 相似文献
985.
The synthesis of CF(3)OC(O)OOC(O)F is accomplished by the photolysis of a mixture of (CF(3)CO)(2)O, FC(O)C(O)F, CO, and O(2) at -15 degrees C using a low-pressure mercury lamp. The new peroxide is obtained in pure form in low yield after repeated trap-to-trap condensation and is characterized by NMR, IR, Raman, and UV spectroscopy. Geometrical parameters were studied by ab initio methods [B3LYP/6-311+G(d)]. At room temperature, CF(3)OC(O)OOC(O)F is stable for many days in the liquid or gaseous state. The melting point is -87 degrees C, and the boiling point is extrapolated to 45 degrees C from the vapor pressure curve log p = 8.384 - 1715/T (p/mbar, T/K). A possible mechanism for the formation of CF(3)OC(O)OOC(O)F is discussed, and its properties are compared with those of related compounds. 相似文献
986.
Nuray Ulusoy Muammer Kiraz Ömer Küçükbasmacı 《Monatshefte für Chemie / Chemical Monthly》2002,133(10):1305-1315
Summary. New 4-alkyl/aryl-1-((6-(4-bromophenyl)-imidazo[2,1-b]thiazol-3-yl)-acetyl)-3-thiosemicarbazides and 3-alkyl/aryl-2-(((6-(4-bromophenyl)-imidazo[2,1-b]thiazol-3-yl)-acetyl)-hydrazono)-4-thiazolidinones were synthesized from 6-(4-bromophenyl)-imidazo[2,1-b]thiazole-3-acetic acid hydrazide. Their structures were elucidated by elemental analyses and spectroscopic data. All compounds
were tested for antibacterial and antifungal activities. The antimicrobial activities of the compounds were assessed by the
microbroth dilution technique. The compounds were also evaluated for antituberculosis activity against Mycobacterium tuberculosis H37Rv (ATCC 27294); they exhibited varying degrees of inhibition in the in vitro primary screening at 6.25 μg · cm−3. The most active compound was 3-(4-nitrophenyl)-2-(((6-(4-bromophenyl)-imidazo[2,1-b]thiazol-3-yl)-acetyl)-hydrazono)-4-thiazolidinone.
Corresponding author. E-mail: nurayulusoy@yahoo.com
Received December 10, 2001. Accepted (revised) March 1, 2002 相似文献
987.
MacArthur R Sazinsky MH Kühne H Whittington DA Lippard SJ Brudvig GW 《Journal of the American Chemical Society》2002,124(45):13392-13393
Spin-labeled Cys89 of the soluble methane monooxygenase regulatory protein (MMOB) from Methylococcus capsulatus (Bath) binds within 15 +/- 4 A of the hydroxylase (MMOH) diiron center, placing the MMOB docking site in the MMOH "canyon" region on iron-coordinating helices E and F of the alpha-subunit. 相似文献
988.
H. Göktürk C. Eylem S. Hatipoĝlu H. N. Erten 《Journal of Radioanalytical and Nuclear Chemistry》1995,198(2):449-456
The sorption behavior of strontium and barium on kaolinite, bentonite and chlorite-illite mixed clay was studied by radioanalytical techniques using the batch method.90Sr (29.1 y) and133Ba (10.5 y) were used as radiotracers. Characterization of the solid matrices was done by FTIR and XRD spectrometries and specific surface area measurements. Synthetic groundwater was used as the aqueous phase. The variation of the distribution ratioR
d, as a function of metal ion loading was examined. The sorption isotherms were fitted to various isotherm models. The sorption energies were calculated to be in the range of 8–10 kJ/mol suggesting an ion exchange type of sorption mechanism. In detailed experiments, chlorite-illite mixed clay was first presaturated with K+, Sr2+, Ca2+ and Al3+ ions, respectively, prior to sorption studies with Ba2+ ions. The results of Ca2+ pretreated chlorite-illite were very similar to those of natural chlorite-illite, suggesting that the Ba2+ ion exchanges primarily with the Ca2+ ion on the clay minerals. 相似文献
989.
Hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) are two non-reducible cross-links of mature collagen which are formed by a sequence of post-translational modifications. HP is a derivative of three residues of hydroxylysine and is present in almost all mature tissues (e.g., tendons, vessel walls, cartilage, teeth and bone). LP is a derivative of two residues of hydroxylysine and one residue of lysine and is present only in dentine and bone. Neither cross-link is found in normal human skin. HP and LP were purified from commercially available bone gelatine (“ossein hydrolysate”) by preparative reversed-phase HPLC and the degree of purity was verified by amino acid determination ( > 98% dry mass). Hydroxylysylpyridinoline and lysylpyridinoline are promising markers in urine of collagen resorption because their levels in urine should reflect only the breakdown of collagen fibres of skeletal tissues. The two components were used as external standards and the determination of HP and LP in urine provides a good means for the specific evaluation of pathological conditions associated with increased bone resorption, e.g., high turnover post-menopausal osteoporosis. 相似文献
990.
Deacon GB Evans DJ Junk PC Lork E Mews R Zemva B 《Dalton transactions (Cambridge, England : 2003)》2005,(13):2237-2238
Addition of 15-crown-5 to [GdF(AsF6)2], both dissolved in liquid SO2, and crystallisation at -30 degrees C has led to the isolation of the tetranuclear ionic complex [Gd4F7(15-crown-5)4][AsF6]5.6 SO2 which is stable up to--10 degrees C where SO2 loss leads to loss of crystallinity. 相似文献