Thermodynamic Studies of Bi-Univalent Electrolytes. VI. Thermodynamics of Cadmium Acetate from E. M. F. and Calorimetric Measurements

E. M. F. of the Cell, Cd-Hg (2-phase)/CdAc₂(m), Hg₂Ac₂(s)/Hg was measured at 20°, 25°, 30° and 40°C. The standard e. m. f. of the cell, Cd/CdAc₃(m), Hg₂Ac₂(c)/Hg was evaluated as E°=1.1500?11.09×10^?4T+1.06×10^?8T² The thermodynamic data of the reaction, Cd(c) + Hg₂Ac₂(c)=2Hg(l)+Cd⁺⁺(aq)+2Ac^?(aq) at 25°C were estimated as ΔF°=?42,139, ΔH°=?48,698 cal mole^?1 and ΔS°=?22.0 cal deg^?1 mole^?1 at 25°C. The thermodynamic data for the formation of Hg₂Ac₂(s) were evaluated as ΔF_f°=?202.3, ΔH_f°=?154.5 Kcal mole^?1 and S°=72.9 cal deg^?1 mole^?1. From measurements of the heats of solution of CdAc₂·2H₂O in aqueous solution, the relative partial molal enthalpies of cadmium acetate in aqueous solution were estimated.     

Optical properties of ZnO and ZnO:In nanorods assembled by sol-gel method

Self-assembled zinc oxide (ZnO) and indium-doping zinc oxide (ZnO:In) nanorod thin films were synthesized on quartz substrates without catalyst in aqueous solution by sol-gel method. The samples were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), Raman-scattering spectroscopy, room-temperature photoluminescence (PL) spectra, and temperature-dependent PL spectra measurements. XRD and Raman spectra illustrated that there were no single In2O3 phase in ZnO lattice after indium doping. The PL spectra of ZnO showed a strong UV emission band located at 394 nm and a very weak visible emission associated with deep-level defects. Indium incorporation induced the shift of optical band gap, quenching of the near-band-edge photoluminescence and enhanced LO mode multiphonon resonant Raman scattering in ZnO crystals at different temperatures. Abnormal temperature dependence of UV emission integrated intensity of ZnO and ZnO:In samples is observed. The local state emission peak of ZnO:In samples at 3.37 eV is observed in low-temperature PL spectra. The near-band-edge emission peak at room temperature was a mixture of excitons and impurity-related transitions for both of two samples.     

Mild hydrothermal synthesis and magnetic properties of the manganates Pr1−xCaxMnO3

The calcium-doped manganates, Pr_1−xCa_xMnO₃ (x=0.39, 0.46, 0.70, 0.76), were synthesized as cube-shaped crystalline phases under mild hydrothermal conditions for the first time. The crystals could be grown in one step from solutions of metal salts and potassium hydroxide at temperatures ∼240 °C, and found to adopt perovskite-like structure (space group Pbnm). Samples were characterized by powder X-ray diffraction, scanning electron microscopy, inductively coupled plasma analysis and variable temperature dc/ac magnetic susceptibility. The studies indicate that formation of the materials is dependent on the alkalinity and composition of the initial reaction mixtures. The magnetic properties show spin-glass-like behavior due to competing ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions in Pr_1−xCa_xMnO₃ with x=0.39, 0.46.     

纳米分辨率的三维形貌检测仪

从光干涉方式，瞳窗关系和光源带宽等基本关系出发，利用空间不变系统理论解析了相移显微干涉检测系统中衍射效应的影响。为了减小横向分辨率对纵向分辨率的影响，利用相关信息提取或数字滤波的方法，获得了纳米分辨率的三维形貌。     

Laser-assisted electron capture by a fast proton from a hydrogen atom

The first Born approximation is used to study the laser-assisted electron capture by a fast proton from a hydrogen atom. The laser modification on differential cross section peaks sharply in the forward direction. With the impact energy increasing, the change in integral cross section becomes notable. The more intense the laser, the greater the cross section is; the lower the frequency, the greater the cross section.     

An Infrared Investigation of Hydrogen-Bonded Liquids

This is an experimental study of the hydrogen-bonded butanediols. Infrared spectra of those butanediols were recorded for pure liquid and vapor phase. Although those molecules do not have any symmetry, with the aid of normal coordinate analysis of n-butane, assignments have been made for all observed infrared frequencies.     

Study on the Tautomer Interconversion of 3-Oxo Pentanoate During Gas Chromatography

Enol and keto tautomers of methyl 3-oxo pentanoate could be separated on a HP-5 capillary column. The chromatographic peaks were identified by examining characteristic mass ions arose from the corresponding enol and keto molecular ions. The study showed that the area percentage of enol tautomer is a function of temperature of the column. Treating the column as a reactor, the energy of activation for the on-column tautomerization could be extracted (35.1 kJ mol⁻¹) by monitoring the loss of the enol tautomer, because the reaction is found to obey pseudo first-order kinetics. The enthalpy and the entropy changes (ΔH = −3.98 kJ mol⁻¹, ΔS = −7.89 J K⁻¹mol⁻¹) for the enol-to-keto reaction in the stationary phase were also obtained.     

High-voltage capillary zone electrophoresis of red blood cells

The high-voltage wide-bore capillary zone electrophoresis of red blood cells was investigated. The reproducibility of the retention time (electrophoretic mobility) is excellent and the differentiation among various species is good. The peaks in the electropherogram describe the distribution of the size and/or surface charge of the cells and are therefore broad. The relationship between the peak height and the number of cells injected is good, with linear correlation coefficients better than 0.98. Details of the preparation of cell suspensions and support electrolytes are given, which is essential for obtaining reproducible results. The inner surface of FEP capillary tubing is degraded by the application of high voltage and a pause is necessary between successive experiments if good and reproducible peak shapes are to be obtained. The length of the pause increases with the number of experiments made, and finally the tubing becomes useless. Inspection of the inner surface by X-ray photoelectron spectroscopy showed the breakdown of CHF bonds, but the actual mechanism is not known.     

Theoretical investigation of the mechanisms of reaction of NCN with NO and NS

Quantum-chemical calculations were performed on the mechanisms of reaction of NCN with NO and NS. Possible mechanisms were classified according to four pathways yielding products in the following four possible groups: N2O/N2S + CN, N2 + NCO/NCS, N2 + CNO/CNS, and CNN + NO/NS, labeled in order from p1/p1s to p4/p4s. The local structures, transition structures, and potential-energy surfaces with respect to the reaction coordinates are calculated, and the barriers are compared. In the NCN + NO reaction, out of several adduct structures, only the nitroso adduct NCNNO lies lower in energy than the reactants, by 21.89 kcal/mol; that adduct undergoes rapid transformation into the products, in agreement with experimental observation. For the NS counterpart, both thionitroso NCNNS and thiazyl NCNSN adducts have energies much lower than those of the reactants, by 43 and 29 kcal/mol, respectively, and a five-membered-ring NCNNS (having an energy lower than those of the reactants by 36 kcal/mol) acts as a bridge in connecting these two adducts. The net energy barriers leading to product channels other than p4s are negative for the NS reaction, whereas those for the NO analogue are all positive. The channel leading to p1 (N2O + CN) has the lowest energy (3.81 kcal/mol), whereas the channels leading to p2 (N2 + NCO) and p2s (N2 + NCS) are the most exothermic (100.94 and 107.38 kcal/mol, respectively).     

Theoretical Study of Weakly Bound Dimers between Hydrogen Fluoride and Some Polar Molecules

Weakly bound linear and bent dimers, FH—X (where X = CO, OC, CNH, NCH, N₂O and ON₂), are investigated using the DFT B3LYP and ab initio MP2 methods with the same basis sets (6–311++G(3df,2pd)). The strengths of the H—C or H—N H‐bonds in dimers FH—CO, FH—CNH, and FH—N₂O are compared with those of the H—O or H—N H‐bonds in dimers FH—OC, FH—NCH, and FH—ON₂. The results obtained for the H‐bond distances, the elongation effect of the HF bond, the red shift of the HF stretching frequency, and the energy difference between the dimer and the charge transfer reveal that the H‐bonds of the first group of dimers are stronger than those of the second. The Gibbs energies calculated for the six dimer formations indicate that the weakly bound dimers are unstable at room temperature (T = 298 K) (FH—X's → FH + X's, ΔG < 0).