Modal analysis of the 0th order nulled phase masks

A simple modal analysis (MA) method to explain the diffraction process of 0th order nulled phase mask is presented. In MA, multiple reflections of the grating modes at grating interfaces are considered by introducing equivalent Fresnel coefficients. Analytical expressions of the diffraction efficiencies and modal guidelines for the 0th order nulled phase grating design are also presented. The phase mask structure, which comprises a high-index contrast HfO 2 grating and a fused-silica substrate, is optimized using rigorous coupled-wave analysis around the 800-nm wavelength, after which the modal guideline for cancellation of the 0th order in a phase mask is verified. The proposed MA method illustrates the inherent physical mechanism of multiple reflections of the grating modes in the diffraction process, which can help to analyze and design both low-contrast and high-contrast gratings.     

Comparison of oxidation polymerization methods of thiophene in aqueous medium and its mechanism

Precipitation method of oxidation polymerization for preparing polythiophene was carried out as well as dispersion and emulsion methods in aqueous medium by using (NH₄)₂S₂O₈ and CuCl₂ as the oxidant and catalyst, respectively. In precipitation method, ethanol was served as an auxiliary solvent to water. The effective conjugated length (ECL) of the obtained polythiophene was demonstrated to be evaluated by the UV absorption spectrum. The ECL of the polythiophene gradually increases with the rise of the content of ethanol in the mixed solvent in precipitation polymerization, and it was higher comparing to the ECL of the product prepared by aqueous dispersion or emulsion method. An electron transition mechanism of the oxidation polymerization of thiophene was suggested.     

Distribution of rare earth elements in the estuarine and coastal sediments of the Daliao River System, China

The Daliao River System (DRS) estuary in Liaodong Bay features a highly industrial, urbanized, and agricultural catchment. The objective of this study was to determine the content, behavior, and distribution of the rare earth elements (REEs) in the estuarine and coastal sediments. To this end, 35 sediment samples were collected from the estuarine and coastal area and analyzed for REEs, Fe, Al, and Mn. The mean concentrations in mg kg^?1 of the sediments were 33.4 (La), 64.1 (Ce), 7.9 (Pr), 29.0 (Nd), 5.4 (Sm), 1.2 (Eu), 4.2 (Gd), 0.78 (Tb), 4.0 (Dy), 0.84 (Ho), 2.3 (Er), 0.40 (Tm), 2.3 (Yb), and 0.37 (Lu). The REE concentrations in the sediments were significantly correlated with one another (r ²  = 0.959–0.988) and the concentrations of Fe, Al, and Mn (r ²  = 0.768–0.870). The total concentration ∑REE ranged from 73.5 to 203.5 mg kg^?1, with an average of 156.0 mg kg^?1 being observed, and generally higher in the estuarine sediments than in the coastal sediments, most likely due to the salt-induced coagulation of river colloids and subsequently their accumulation at the estuarine bottom. The ratio of light REEs (∑LREE) to heavy REEs (∑HREE) was 9.4. Chondrite-normalized REE distributions were observed to be similar for the estuarine and coastal sediments, riverine suspended particles, and watershed soils of the DRS with higher LRRE enrichment than HREE and greater Eu depletion than Ce depletion. These results demonstrate that neither geochemical processes that carry soils to estuarine sediments nor long-term industrial and agricultural activities alter the distribution or fractionation of the REEs in the study area.     

A Novel Multifunctional α-Amylase from the Thermophilic Fungus Malbranchea cinnamomea: Biochemical Characterization and Three-Dimensional Structure

A novel α-amylase (McAmyA) from the thermophilic fungus, Malbranchea cinnamomea was purified, characterized and crystallized in the present study. McAmyA was purified to apparent homogeneity with a molecular mass of 60.3 kDa on SDS-PAGE. The enzyme exhibited maximal activity at pH 6.5 and was stable within pH 5.0–10.0. It was most active at 65 °C and was stable up to 50 °C. McAmyA was capable of hydrolyzing amylose, starch, amylopectin, pullulan, cyclodextrins and maltooligosaccharides. The full-length cDNA of an α-amylase gene (McAmyA) from the strain was cloned. McAmyA consisted of a 1,476-bp open reading frame encoding 492 amino acids. It displayed the highest amino acid sequence homology (less than 60 %) with the reported α-amylases. The crystal structure of McAmyA was solved at a resolution of 2.25 Å (PDB code 3VM7). The overall structure of McAmyA reveals three domains with ten α helices and 14 β strands, and the putative catalytic residues are positioned at domain A with somewhat different secondary structural circumstances compared with typical α-amylases.     

梁的载荷、内力微分关系推导方法的改进

在推导梁截面上的剪力、弯矩与分布载荷集度之间的关系时, 流行的《材料力学》教材 采用的推导过程在数学上失于严密. 根据导数定义和洛必达(L'Hospital)法则(或积分中 值定理)给出了逻辑严密的推导.     

Mie散射系数计算方法的研究

介绍一种计算Mie散射系数的新方法，给出计算实例。     

基于朗伯定律重建光学三角法测位移原理公式

利用朗伯定律重构了光学三角法测位移的原理公式，与用几何光学原理建立的公式进行了比较。利用新公式对影响光学三角法漂移精度的主要误差因素进行了深入的分析，给出了实验结果，并提出了减小和校正误差的方法。     

Theoretical study on photophysical properties of phenolpyridyl boron complexes

Organoboron complexes have potential application in organic light-emitting devices (OLEDs). Our group has synthesized four phenolpyridyl boron complexes (Inorg. Chem. 2006, 45, 2788), which can function as an electron transport materials (ETM), white and blue emitters, and exhibit high efficiency and stability. To reveal the relationship between the properties and structures of these functional materials, theoretical analysis of spectral properties and electronic structures of these complexes was systematically characterized with the B3LYP and 6-31G* basis set. The calculated absorption and emission spectra of these systems are in good agreement with the experimental ones. It is clear seen that these transitions are charge transferred along 2,6-bis(2-hydroxyphenyl)pyridyl boron moiety, and the contribution of boron atom in these compounds to the main transition orbitals is vanishingly small. The substitution of methyl and methoxyl for hydrogen does not change the absorption wavelengths and transition natures, but influences the radioactive efficiencies and electron transport properties, which are observed and discussed in detail. Furthermore, large red shifts of fluorescence are caused by replacing the hydrogen with CN or NO2 groups, which indicates that they are potential candidates as green-light-emitting materials. These results are favorable to further understanding the photophysical properties of this kind of complexes.     

随机激励下用子结构法分析圆柱-圆板减振器

提出了用子结构法分析一种边疆体减振器－－圆柱－圆板减振器，仿真结果表明，在不同地震波作用下，圆柱－圆板减振器都可以有较好的减振效果，克服了常见的弹簧－质量模型在不同地震波作用下减振效果变化大的缺点。