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61.
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63.
S.S. Joshi 《Applied Surface Science》2006,252(24):8539-8543
In the present work, for the first time, heterojunction has been fabricated using electrochemically deposited isotype p-selenium-p-polyaniline from a single solution bath. The structural characterization of selenium and polyaniline thin film was carried out using XRD technique. Polyaniline exhibited amorphous structure while selenium offered monoclinic (β) phase. The junction was formed by electrodepositing polyaniline over selenium film and heating at 423 K. The current density versus voltage (J-V) plot showed the formation of a junction with ideality factor of 1.16. From J-V characteristics at different temperatures, static resistance (Rs), dynamic resistance (Rd), and rectification ratio of diodes were determined. Heat treatment above 448 K caused junction breakdown. 相似文献
64.
akir Aydoan Mustafa Salam Abdulmecit Türüt 《Journal of Polymer Science.Polymer Physics》2006,44(11):1572-1579
The polypyrrole/p‐InP structure has been fabricated by the electrochemical polymerization of the organic polypyrrole onto the p‐InP substrate. The current–voltage (I–V), capacitance–voltage (C–V), and capacitance–frequency (C–f) characteristics of the PPy/p‐InP structure have been determined at room temperature. The structure showed nonideal I–V behavior with the ideality factor and the barrier height 1.48 and 0.69 eV respectively. C–f measurements of the structure have been carried out using the Schottky capacitance spectroscopy technique and it has been seen that there is a good agreement between the experimental and theoretical values. Also, it has been seen that capacitance almost show a plateau up to a certain value of frequency, after which, the capacitance decreases. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the p‐InP that can follow the a.c. signal. The interface state density Nss and relaxation time τ of the structure were determined from C–f characteristics. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1572–1579, 2006 相似文献
65.
Both homogeneous and asymmetric polyethersulfone (PES) membranes were prepared by solvent casting. The sorption and permeation behavior of CO2, O2, and N2 using these two kinds of cast PES membranes and commercially available homogeneous PES film was investigated to extract the pressure dependence of gas permeability and the permselectivity for CO2 relative to N2, and to confirm the validity of the working assumption that a skin layer in an asymmetric membrane can be essentially replaced by a thick homogeneous dense membrane. The pressure dependence of the mean permeability coefficient to CO2 in homogeneous membranes obeys the dual-mode mobility model. The ideal separation factor for CO2 relative to N2 at an upstream pressure of 0.5 MPa attains ca. 40, while the permeability to CO2 is about 2.7 Barrer at the same upstream pressure. The same separation factor in asymmetric membranes amounts to 35. The diffusion behavior for the skin layer in an asymmetric membrane with a thin skin layer can be simulated approximately by that in a homogeneous dense membrane. © 1993 John Wiley & Sons, Inc. 相似文献
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67.
Yosihiko Ogata 《Annals of the Institute of Statistical Mathematics》1990,42(3):403-433
This paper describes a method for an objective selection of the optimal prior distribution, or for adjusting its hyper-parameter, among the competing priors for a variety of Bayesian models. In order to implement this method, the integration of very high dimensional functions is required to get the normalizing constants of the posterior and even of the prior distribution. The logarithm of the high dimensional integral is reduced to the one-dimensional integration of a cerain function with respect to the scalar parameter over the range of the unit interval. Having decided the prior, the Bayes estimate or the posterior mean is used mainly here in addition to the posterior mode. All of these are based on the simulation of Gibbs distributions such as Metropolis' Monte Carlo algorithm. The improvement of the integration's accuracy is substantial in comparison with the conventional crude Monte Carlo integration. In the present method, we have essentially no practical restrictions in modeling the prior and the likelihood. Illustrative artificial data of the lattice system are given to show the practicability of the present procedure. 相似文献
68.
We carried out molecular dynamics simulations of a Lorentz gas, consisting of a lone hydrogen molecule moving in a sea of stationary argon atoms. A Lennard-Jones form was assumed for the H2-Ar potential. The calculations were performed at a reduced temperatureK
* =kT/H
2–Ar = 4.64 and at reduced densities
*=
Ar
Ar
3
in the range 0.074–0.414. The placement of Ar atoms was assumed to be random rather than dictated by equilibrium considerations. We followed the trajectories of many H2 molecules, each of which is assigned in turn a velocity given by the Maxwell-Boltzmann distribution at the temperature of the simulation. Solving the equations of motion classically, we obtained the translational part of the incoherent dynamic structure factor for the H2 molecule,S
tr(q, ). This was convoluted with the rotational structure factorS
rot(q, ) calculated assuming unhindered rotation to obtain the total structure factorS(q, ). Our results agree well with experimental data on this function obtained by Egelstaffet al. At the highest density (
*=0.414) we studied the dependence ofS(q, ) on system size (number of Ar atoms), number of H2 molecules for which trajectories are generated, and the length of time over which these trajectories are followed. 相似文献
69.
70.
因子分析—伏安法同时测定波峰重叠的混合物组份 总被引:3,自引:1,他引:3
本文将目标因子分析用于伏安分析法同时测定波峰重叠的混合物组份。用此法对Pb(Ⅱ)、Tl(I)混合体系的导数脉冲伏安重叠峰数据进行解析,获得了较理想的结果。 相似文献