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31.
βbc-Nickel hydroxide exhibit non-uniform broadening reflections in their PXRD pattern due to the presence of structural disorder.
βbc-Nickel hydroxide electrodes with smaller crystallite size and structural disorder reversibly exchanges 0.9e/Ni. Co/Zn/Ca/Cd-substituted
βbc-nickel hydroxide samples also display non-uniform broadening of reflections in their powder X-ray diffraction patterns with
smaller crystallite size and exchanges 0.7–0.8e/Ni. Hydrothermal treatment of βbc-nickel hydroxide slurry at 170 °C results in an ordering of reflections in their powder X-ray diffraction pattern with an
increased crystallite size. Crystalline β-nickel hydroxide electrode reversibly exchanges 0.3–0.4e/Ni. Hydrothermal-treated
Co/Zn/Ca/Cd-substituted βbc-nickel hydroxide slurries at 170 °C display sharp reflections with similar crystallite size and electrochemical activities
as that of crystalline β-nickel hydroxide. This clearly demonstrates that partial substitution of Co/Zn/Ca/Cd in the nickel
hydroxide matrix does not show any dramatic improvement in their electrochemical activity at 25–30 °C. Structural disordered
material with smaller crystallite size delivers electrochemical activity close to theoretical capacity. 相似文献
32.
33.
Different hydrates of calcium oxalate have been electrodeposited by electrogeneration of acid at the anode from an EDTA-stabilized calcium nitrate bath containing dissolved oxalate ions. The deposition is controlled by varying the bath pH, temperature, and current density. Formation of metastable CaC2O4·2H2O is favored at high current densities at ambient temperature, whereas the thermodynamically stable CaC2O4·H2O is formed at elevated bath temperatures. Both the polymorphs show oriented growth with respect to the substrate normal under different deposition conditions. 相似文献
34.
Lubna N Kamath G Potoff JJ Rai N Siepmann JI 《The journal of physical chemistry. B》2005,109(50):24100-24107
An extension of the transferable potentials for phase equilibria united-atom (TraPPE-UA) force field to thiol, sulfide, and disulfide functionalities and thiophene is presented. In the TraPPE-UA force field, nonbonded interactions are governed by a Lennard-Jones plus fixed point charge functional form. Partial charges are determined through a CHELPG analysis of electrostatic potential energy surfaces derived from ab initio calculations at the HF/6-31g+(d,p) level. The Lennard-Jones well depth and size parameters for four new interaction sites, S (thiols), S(sulfides), S(disulfides), and S(thiophene), were determined by fitting simulation data to pure-component vapor-equilibrium data for methanethiol, dimethyl sulfide, dimethyl disulfide, and thiophene, respectively. Configurational-bias Monte Carlo simulations in the grand canonical ensemble combined with histogram-reweighting methods were used to calculate the vapor-liquid coexistence curves for methanethiol, ethanethiol, 2-methyl-1-propanethiol, 2-methyl-2-propanethiol, 2-butanethiol, pentanethiol, octanethiol, dimethyl sulfide, diethyl sulfide, ethylmethyl sulfide, dimethyl disulfide, diethyl disulfide, and thiophene. Excellent agreement with experiment is achieved, with unsigned errors of less than 1% for saturated liquid densities and less than 3% for critical temperatures. The normal boiling points were predicted to within 1% of experiment in most cases, although for certain molecules (pentanethiol) deviations as large as 5% were found. Additional calculations were performed to determine the pressure-composition behavior of ethanethiol+n-butane at 373.15 K and the temperature-composition behavior of 1-propanethiol+n-hexane at 1.01 bar. In each case, a good reproduction of experimental vapor-liquid equilibrium separation factors is achieved; both of the coexistence curves are somewhat shifted because of overprediction of the pure-component vapor pressures. 相似文献
35.
Summary: The effects of copolymer sequence distribution on the dynamics of a copolymer in a homopolymer matrix are studied using computer simulations within the framework of the bond‐fluctuation model on blends containing low concentrations (10%) of copolymers dispersed in a homopolymer matrix. The sequence distribution of the two copolymer components was changed while maintaining the overall copolymer composition at 50/50. Our results indicate that copolymers with disordered sequence distributions exhibit dynamics that are faster than that of a homopolymer melt, while those with ordered sequence distributions exhibit a tendency to form aggregates that lead to slower dynamics as well as phase separation. Analysis of the structure suggests that copolymers with an alternating sequence distribution form large aggregates that are short‐lived, while diblocks form permanent micelle‐like structures. Analysis of the local composition around a copolymer molecule indicates that aggregation between copolymer chains has a direct impact on the local composition. This in turn has a significant impact on system dynamics. Our results indicate that the dynamics of random, random‐blocky, and alternating copolymers are nearly identical and are faster than that of a homopolymer melt. However, alternating copolymers form aggregates and hence are not uniformly distributed throughout the matrix phase. Thus, alternating copolymers are at a disadvantage in their ability to be effective compatibilizers. From a dynamic perspective, copolymers with random and random‐blocky copolymers seem to be ideal compatibilizers since they are distributed uniformly throughout the system and move rapidly through the matrix phase.
36.
Y B S R Prasad V K Senecha H C Pant M P Kamath G S Solanki P K Tripathi A P Kulkarni S Gupta R Pareek A S Joshi N Sreedhar Sameer Nigam C P Navathe 《Pramana》2000,55(5-6):797-802
The x-ray emission from slab targets of copper irradiated by Nd:glass laser (1.054 μm, 5 and 15 ns) at intensities between 1012 and 1011W/cm2 has been studied. The x-ray emissions were monitored with the help of high quantum efficiency x-ray silicon photo diodes
and vacuum photo diodes, all covered with aluminium filters of different thickness. The x-ray intensity vs the laser intensity
has a scaling factor of (1.2–1.92). The relative x-ray conversion efficiency follows an empirical relationship which is in
close agreement with the one reported by Babonneau et al. The ion velocities were monitored using Langmuir probes placed at different angles and radial distances from the target
position. The variation of the ion velocity with the laser intensity follows a scaling of the form Φ
β
where β ∼0.22 which is in good agreement with the reported scaling factor values. The results on the x-ray emission from Cu plasma
are reported. 相似文献
37.
Abstract We present the results of high-pressure, high-temperature studies on xerogel gamma alumina which is made up of nanocrystalline alumina and an amorphous phase. Not many studies of this type have been reported on xerogel materials. At about 5 GPa and 1400°C, the xerogel alumina transforms into a polymorphic mixture containing α Al2O3, B Al2O3 and C Al2O3 where the last two phases have B Ln2O3 and C Ln2O3 type structures respectively. Here Ln stands for the rare earths. The xerogel alumina containing 1 wt.% Cr2O3 under these conditions transforms into a polymorphic mixture containing Al2O3, k' Al2O3 and H Al2O3 where H Al2O3 has the H Ln2O3 type structure. For the first time, the observation of rare earth sesquioxide structures of alumina is reported. At about 5 GPa at 27°C, the xerogel aluminal transforms to an amorphous phase. The results are discussed using the free energy diagram for xerogels proposed by R. Roy (J. Amer. Cer. Soc., 52, 344, 1969; 67, 468, 1984). 相似文献
38.
Srikanth S. Kamath 《Journal of Dispersion Science and Technology》2013,34(9):1304-1310
A spray drying technique was applied to prepare composite microparticles of a water-insoluble herbicide, atrazine(AT) and a water-soluble herbicide 2,4-dichloro phenoxy acetic acid (2,4-D) for the purpose of improving the water solubility of AT. A homogenous mixture of an ethanol solution of AT and an aqueous 2,4-D solution at different ratios were spray dried using a laboratory scale spray drier. Quantitative elemental analysis suggested that the AT/2,4-D ratio in each composite microparticle was nearly the same as the desired formulation ratio. The resulting samples were characterized by powder x-ray diffractometry (XRD), differential scanning calorimetry (DSC), Fourier transform infra red (FT-IR) and scanning electron microscopy (SEM). It was found that the crystallinity of AT and 2,4-D were maintained in the composite particles. Moreover, the release of AT from dissolved composite microparticles was markedly improved because of an increase in the effective surface area following rapid dissolution of 2, 4 D. Hence, this study shows that it is possible to prepare AT-2,4-D composite microparticles using a laboratory scale spray drier and that this can improve the ability of AT to dissolve in water. 相似文献
39.
M. Kamath J. O. Lim K. G. Chittibabu R. Sarma J. Kumar K. A. Marx 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):493-502
Abstract Copolymers of 3-substituted thiophenes have been synthesized by organosynthetic routes. The chemical synthesis of the copolymer was carried out by dehydrogenation of 3-hexylthiophene and 3-methanolthiophene. Attachment of biotin to the resulting copolymer, poly(3-hexylthiophene-co-3-methanolthiophene) [PMHT], is accomplished by room temperature esterification using N,N-dicyclohexylcarbodiimide (DCC) and 4-pyrrolidinopyridine as catalyst. The resulting copolymers have well-defined chemical and electronic structures and molecular weights. The biotinylated copolymer forms a stable monolayer at the air-water interface due to the polar groups along the polymer backbone. 相似文献
40.
Based on XPS and UVPS studies, it is shown that oxygen is preferentially adsorbed molecularly in the singlet state on Cu and Ag surfaces containing presorbed chlorine. Adsorption of chlorine on Cu and Ag surfaces containing presorbed atomic oxygen causes a disappearance of the oxygen. Extended Hückel calculations predict the observed behaviour. 相似文献