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61.
62.
K3 [Fe(CN)6] and KFe[Fe(CN)6] are classical coordination compounds. However, the mechanism of decomposition reactions has not been well expounded. The gas products of thermal decomposition were examined by gas chroma tography (GC) , and the structure of the solid products by Mossbauer spectroscopy(MS) and X-ray diffraction(XRD). The findings are explained in terms of the theory of coordination chemistry and a decomposition mechanism is proposed in this study. On the basis of various experimental results, the first stage of the decomposition of K3[Fe(CN)6] in He was found to be the evolution of(CN)2 resulting in the reduction of Fe(Ⅲ)12K3 [Fe(CN)6]→9K4[Fe(CN)6] + Fe2 [Fe(CN)6] + 6 ( CN )For KFe [Fe(CN) 6 ], the first stage of decomposition man be represented as6KFe[Fe(CN)6]→3K2Fe[Fe(CN)6] + 2Fe2[Fe(CN)6 + 3(CN)2At higher temperatures, the decomposition of both K3[Fe(CN)6) andKFe[Fe(CN)6] to form KCN and Fe2C was accomplished by the release of(CN)2 and N2. 相似文献
63.
Density functional theory (DFT) and Monte Carlo (MC) simulation with free energy perturbation (FEP) techniques have been used to study the tautomeric proton transfer reaction of 2-amino-2-oxazoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline in the gas phase and in water. Two reaction pathways were considered: the direct and water-assisted transfers. The optimized structures and thermodynamic properties of stationary points for the title reaction system in the gas phase were calculated at the B3LYP/6-311+G(d, p) level of theory. The potential energy profiles along the minimum energy path in the gas phase and in water were obtained. The study of the solvent effect of water on the proton transfer of 2-amino-2-oxozoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline indicates that water as a solvent is favorable for the water-assisted process and slows down the rate of the direct transfer pathway. 相似文献
64.
65.
Chitosan samples were irradiated by 60Co γ-rays in the presence of hydrogen peroxide with radiation dose from 10 kGy to 100 kGy. The degradation was monitored by gel permeation chromatography (GPC), revealing the existence of a synergetic effect on the degradation. Structures of the degraded products were characterized with Fourier-transform infrared spectra (FT-IR), ultraviolet-visible spectral (UV-vis) analysis, and X-ray diffraction (XRD). Results showed that the crystallinity of chitosan decreases with degradation, and the crystalline state of water-soluble chitosan is entirely different from that of water-insoluble chitosan. An elemental analysis method was employed to investigate changes in the element content of chitosan after degradation. Mechanism of chitosan radiation degradation with and without hydrogen peroxide was also discussed. 相似文献
66.
Ce0.6Zr0.35Y0.05O2和Pr0.6Zr0.35Y0.05O2催化剂表面上CO氧化和18O-16O交换反应的研究 总被引:5,自引:0,他引:5
测定了在Ce0.6Zr0.4O2,Ce0.6Zr0.35Y0.05O2,Pr0.6Zr0.4O2和Pr0.6Zr0.35Y0.05O2 (分别表示为CZ,CYZ,PZ和PYZ)样品表面上的CO氧化反应和18O-16O 同位素交换反应.结果表明: 在CZ和PZ系列固熔中掺杂Y3 离子可以改善晶格氧的迁移速度;PZ和PZY的晶格氧比CZ 和CZY 的晶格氧具有更高的氧化反应活性.其原因是将Y3 掺杂到Ce0.6Zr0.4O2 或Pr0.6Zr0.4O2晶格中,增加了样品的氧空位浓度,从而提高了晶格氧的迁移性质,而PrOx比CeO2具有更低温度的氧化还原性质,因此PZ和PZY的晶格氧比CZ 和CZY 的晶格氧具有更高的氧化反应活性. 相似文献
67.
Mechanical properties of BPDA-ODA polyimide fibers 总被引:1,自引:0,他引:1
An aromatic polyimide was synthesized via a one-step polycondensation reaction between biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-oxydianiline (ODA) in p-chlorophenol. The polyimide (BPDA-ODA) solution dopes were spun into fibers by means of dry-jet wet spinning. The as-spun fibers were drawn and treated in heating tubes for improving the mechanical properties. The thermal treatment on the fibers resulted in a relatively high tensile strength and modulus. Thermal mechanical analysis (TMA) was employed to study the linear coefficient of thermal expansion (CTE). Thermal gravimetry analysis (TGA) spectra showed that the BPDA-ODA fibers possessed an excellent property of thermo-oxidative degradation resistance. The sonic modulus Es of the polyimide fibers was measured. 相似文献
68.
Ultra-long single-crystalline trigonal selenium submicrotubes were synthesized using a facile one-step solution-phase approach with the assistance of nonionic surfactant Polyoxyethylene(20)sorbitan monolaurate (Tween-20), which turned out to be significant for the formation of ultra-long Se submicrotubes. XRD, Raman, SEM, and TEM were adopted to characterize the morphology, structure and phase composition of the as-prepared Se products. It was found that the length of the obtained Se submicrotubes was over 100 microm. By variation of the experimental parameters, the t-Se spheres, nanowires, and broken microtubes can be prepared. The possible growth mechanism of the ultra-long selenium submicrotubes was explained. In addition, we have also demonstrated that the synthesized ultra-long t-Se submicrotubes using the Tween-20-assisted approach can electrochemically charge and discharge with the high capacity of 265 mAh/g (corresponding to 0.97 wt % hydrogen in SWNTs) under normal atmosphere at room temperature. Cyclic voltammetry was adopted to investigate the adsorption-oxidation behavior of ultra-long selenium submicrotubes. It was observed that the morphology of the synthesized selenium products had a remarkable influence on their capacity of electrochemical hydrogen storage. These differences in hydrogen storage capacity are likely due to the size and density of tubes as well as the microcosmic morphology of different Se samples. The as-obtained ultra-long Se submicrotubes are expected to find wide applications in hydrogen storage, high-energy batteries, and optoelectronic, biologic, and catalytic fields as well as in the studies of structure-property relationships. This simple Tween-assisted approach might be extended to the preparations of one-dimensional nanostructures of tellurium and other anisotropic materials. 相似文献
69.
Potentiodynamic deposition of Prussian blue from a solution containing single component of ferricyanide and its mechanism investigation 总被引:1,自引:0,他引:1
Dai?Zhang Kang?Wang Dacheng?Sun Xinghua?XiaEmail author Hongyuan?Chen 《Journal of Solid State Electrochemistry》2003,7(9):561-566
Potentiodynamic techniques were used for the direct electrodeposition of Prussian blue nano-clusters from an acidic solution of ferricyanide. Electrochemical, EQCM, IR, AFM, and UV/vis measurements were carried out to characterize deposited nano-sized Prussian blue and to explore the formation mechanism. Results showed that ferricyanide could partially dissociate to free ferric and cyanide ions. The driving force of this dissociation is the formation of PB and the evolution of HCN. The optimal potential window for the potentiodynamic formation of PB from an acidic solution (pH 1.6) is between –0.5 V and 0.4 V. In addition, the influence of surface adsorption of CN- ions on the formation of PB was discussed.Dedicated to Professor W. Vielstich on the occasion of his 80th birthday. 相似文献
70.
茶叶中三氯螨杀醇残留量的快速HPLC测定法 总被引:3,自引:0,他引:3
用微量化技术处理茶叶样品,样品经石油醚提取、浓硫酸磺化后,用反相液相色谱分离、测定样品处理液中的三氯杀螨醇残留量,234nm检测,外标法定量。测定低限为0.5mg/kg,回收率为91.5%~99.3%,变异系数为1.53%~6.92%之间。 相似文献