Log-polynomial period functions for nondiscrete Hecke groups

Existence of automorphic integrals associated with nondiscrete Hecke groups will be considered. Multiplier systems for some of these groups will be discussed.

     

Electrical properties of purified solar grade silicon substrates using a combination of porous silicon and SiCl4

This work investigates the photo-thermal treatment of solar grade (SG) silicon to reduce impurities to a low level suitable for high efficiency low-cost solar cells application. It describes experiment carried out by using a tungsten lamps furnace (rapid thermal processing, RTP) to purify solar grade silicon wafers using a combination of porous silicon (PS) and silicon tetrachloride. This process enables to attract the impurities towards the porous layer where they react with SiCl₄ to form metallic chlorides. The gettering effect was studied using the Hall Effect and the Van Der Pauw methods to measure the resistivity, the majority carrier concentration and mobility. We have obtained a significant improvement of the majority carrier mobility after such thermo-chemical treatment. The gettering efficiency is also evaluated by the relative increase of the minority carrier diffusion length L, measured by the light beam induced current (LBIC) technique.     

Effect of carriers localized in clusters on optical properties of In0.21Ga0.79As/GaAs multiple quantum wells

In_0.21Ga_0.79As multiple quantum wells MQW, with different well thickness L, are grown on [001] and [113] A GaAs growth directions by molecular beam epitaxy MBE. An asymmetric photoluminescence PL line shape denoted LE_A and LE_B in the lower energies side has been observed in both structures. These emissions of deep localized states can be related to the energy potential modulation associated to Indium cluster formation. Temperature dependence of photoluminescence properties has been reported. Localized state ensemble LSE model has investigated atypical behaviors of PL peak energies and the full width at half maximum FWHM of both emissions. These abnormal behaviors are explained by carriers captured by localized recombination centers. Competition processes between localized and delocalized excitons have been occurred to interpret the PL properties. The degree of localization induced by quantum-dot-like states and critical temperatures between different temperatures regions increase as far as away [001] growth direction.     

Potassium cerium(III) bis­(sulfate) monohydrate,KCe(SO4)2·H2O

The crystal structure of potassium cerium(III) bis­(sulfate) monohydrate, KCe(SO₄)₂·H₂O, is built up from irregular independent SO₄ tetra­hedra, CeO₉ polyhedra in the form of distorted tricapped trigonal prisms and K⁺ ions. Hydrogen bonding between the free water mol­ecule and sulfate groups supplement the ionic bonds characteristic of the rest of the structure.     

Combined Effect of Dissipation and Thermal Mixed State on Entanglement in the Dispersive Limit

We investigate the entanglement in the interacting system of a single mode thermal field and a single qubit with dissipation in the dispersive limit. The influence of initial temperature of thermal field and atoms on the entanglement is then examined.     

The dynamic behavior of MEMS arch resonators actuated electrically

In this paper, we investigate the dynamic behavior of clamped-clamped micromachined arches when actuated by a small DC electrostatic load superimposed to an AC harmonic load. A Galerkin-based reduced-order model is derived and utilized to simulate the static behavior and the eigenvalue problem under the DC load actuation. The natural frequencies and mode shapes of the arch are calculated for various values of DC voltages and initial rises. In addition, the dynamic behavior of the arch under the actuation of a DC load superimposed to an AC harmonic load is investigated. A perturbation method, the method of multiple scales, is used to obtain analytically the forced vibration response of the arch due to DC and small AC loads. Results of the perturbation method are compared with those obtained by numerically integrating the reduced-order model equations. The non-linear resonance frequency and the effective non-linearity of the arch are calculated as a function of the initial rise and the DC and AC loads. The results show locally softening-type behavior for the resonance frequency for all DC and AC loads as well as the initial rise of the arch.     

Elastoplastic analysis of soil-structures strengthened by two-directional reinforcements using a multiphase approach

A multiphase model for assessing the macroscopic behavior of earth structures reinforced by two-dimensional inclusions in the context of elastoplasticity is presented and incorporated into a finite element based numerical tool with an appropriate return mapping algorithm. The obtained numerical tool is applied to the stability analysis of an axisymmetric reinforced soil-structure and a parametric study is then considered for different interaction conditions between the soil and the reinforcing membranes, corresponding to a perfect bonding assumption, a perfectly smooth interface and an intermediate case. The stability factors quantified by this study for the different cases are then compared to those obtained by a yield design analysis.     

多孔聚苯醚的合成及气体储存

通过厄尔曼缩合反应合成了一种具有dia-c5 拓扑结构的多孔聚苯醚JUC-Z6, 并对其结构进行了表征. 结果表明, 该化合物具有高热稳定性(214℃ 失重5%), 高化学稳定性、 高BET比表面积(192 m²/g)及窄孔径分布(1.36 nm). 低压气体吸附测试结果表明, JUC-Z6在多孔材料中具有较高的吸附焓(氢气4.1 kJ/mol, 二氧化碳33.7 kJ/mol, 甲烷4.1 kJ/mol).     

Theoretical Density Functional Theory insights into the nature of chalcogen bonding between CX2 (X = S,Se, Te) and diazine from monomer to supramolecular complexes

Chalcogen bonding is a noncovalent interaction, highly similar to halogen and hydrogen bonding, occurring between a chalcogen atom and a nucleophilic region. Two density functional theory (DFT) approaches B3LY-D3 and B97-D3 were performed on a series of complexes formed between CX₂ (X = S, Se, Te) and diazine (pyridazine, pyrimidine and pyrazine). Chalcogen atoms prefer interacting with the lone pair of a nitrogen atom rather than with the π-cloud of an aromatic ring. CTe₂ and CSe₂ form a stronger chalcogen bond than CS₂. The electrostatic potential of CX₂ (X = S, Se and Te) reveals the presence of two equivalent σ-holes, one on each chalcogen atom. These CX₂ molecules interact with diazine giving rise to supramolecular interactions. Wiberg bond index and second-order perturbation theory analysis in NBO were performed to better understand the nature of the chalcogen bond interaction.     

Impregnated Sulfur in Carbonized Nitrogen-containing Porous Organic Frameworks as Cathode with High Rate Performance and Long Cycle Life for Lithium-sulfur Batteries

The undesirable cycling performance caused by soluble poly sulfides shuttling between anode and cathode has been considered as the main challenge that has hindered its practical applications for lithium-sulfiir(Li-S) batteries. To solve tliis issue effectively, a nitrogen-containing porous carbon, namely JUC-Z2-900,developed from a porous organic framework, namely JUC-Z2, bearing a high surface area(805 m^2/g),small pore size(0.5 mil) and nitrogen doping(2.15%, mass fraction), has been used as a host material for Li-S batteries. The micropores of JUC-Z2-900 can confine the smaller sulfur molecules S2-4, which can essentially alleviate the critical problem of poly sulfide dissolution.Furthermore, nitrogen-containing JUC-Z2-900 can promote chemical adsorption of sulfur. The above two factors can improve the electrochemical performance of Li-S batteries effectively. To compare the eftects of sulfur contents and melt-difiusion strategy in JUC-Z2-900/S composites, a series of JUC-Z2-900/S composites was synthesized and tlieir electrochemical perfbnnances were explored, indicating good rate performance and excellent cycling stability of the composites contributed by both appropriate mass percentage of sulfiir and its confinement in the micropores.