Calcination temperature optimization,energy transfer mechanism and fluorescence temperature dependence of KLa(MoO4)2:Eu3+ phosphors

The optimum calcination temperature for KLa(MoO₄)₂:Eu³⁺ phosphor was confirmed to be 1000 °C via checking the XRD patterns, SEM images and fluorescence spectra for the samples derived from solid state reaction. The energy transfer behavior between Eu³⁺ ions was studied. It was found that electric dipole–dipole interaction is responsible for the fluorescence quenching of ⁵D₂ and ⁵D₁ levels, but exchange interaction is in charge of ⁵D₀ fluorescence quenching. It was also observed that color coordinates of the studied phosphor can be tuned when the doping concentration is relatively low. The fluorescence thermal quenching process was investigated. It was found the thermal quenching followed well crossover model. Judd–Ofelt parameters of Eu³⁺ in KLa(MoO₄)₂ were obtained, and the optical transition properties were further discussed.     

Substrate effect on the electronic structure in GaxIn1−xAsySb1−y/GaSb and GaxIn1−xAsySb1−y/InAs

We present a theoretical study of the substrate effect on electronic structure in cubic Ga_xIn_1−xAs_ySb_1−y lattice-matched to GaSb and InAs. Our calculations are based on the empirical pseudopotential formalism within the virtual crystal approximation where the effect of disorder is taken into account. We show that the electronic band structure of the quaternary alloy Ga_xIn_1−xAs_ySb_1−y is altered by the change of substrate for the entire range of alloy compositions x. Moreover, we find that at Ga concentrations (x≤0.8), the ionicity is less important when Ga_xIn_1−xAs_ySb_1−y is lattice-matched to GaSb instead of InAs. The information will be useful for the choice of substrate in the composition range 0–1 and hence for the determination of the lattice-matching conditions for Ga_xIn_1−xAs_ySb_1−y quaternary materials.     

Phase equilibria of long-chain polyunsaturated fish oil fatty acid ethyl esters and carbon dioxide,ethane, or ethylene at reduced gas temperatures of 1.03 and 1.13

Phase equilibria of a mixture of long-chain polyunsaturated fish oil fatty acid ethyl esters (FAEEs) with carbon dioxide were measured at 313.2 and 343.2 K, with ethane at 314.0 and 344.6 K, and with ethylene at 290.9 and 318.6 K. The temperatures correspond to reduced gas temperatures of approximately 1.03 and 1.13. The experimental pressures range from 1.6 to 25 MPa. The FAEE mixture is rich in eicosapentaenoic acid ethyl ester (EPA, 52.5 wt.%), and docosahexaenoic acid ethyl ester (DHA, 36.1 wt.%), and a total of 10 components were identified. The experimental temperatures, pressures, solubilities, mass fractions, and calculated equilibrium ratios are reported in tables and graphs. The mass fractions and the equilibrium ratios are reported on a solvent-free basis.     

A subjective and objective integrated approach to determine attribute weights

This paper proposes an integrated approach to determine attribute weights in the multiple attribute decision making (MADM) problems. The approach makes use of the subjective information provided by a decision maker and the objective information to form a two-objective programming model. Thus the resultant attribute weights and rankings of alternatives reflect both the subjective considerations of a decision maker (DM) and the objective information. An example is used to illustrate the applicability of the proposed approach.     

Analysis of compressive failure of layered materials by kink band broadening

Failure by steady state kink band broadening in uni-directional fibre composites or layered materials is analysed. An incremental scheme for calculation of kink band broadening stresses and lock-up conditions in the band for arbitrary material behaviour is presented. The method is illustrated by material data which are representative for polymer matrix composites for which experimental work exists.     

Synthesis of Sm2Co17 alloy nanoparticles by mechanochemical processing

Sm₂Co₁₇ alloy nanoparticles of 10–250 nm in size were prepared by mechanochemical processing involving the co-reduction of Sm₂O₃ and CoO with Ca. The crystal structure of the nano-sized Sm₂Co₁₇ particles was mainly of the ordered Th₂Zn₁₇-type. When embedded in the CaO matrix the Sm₂Co₁₇ nanoparticles exhibited a high coercivity of 14.2 kOe. The CaO by-product could be removed by a carefully controlled washing process without significant oxidation of the ultrafine alloy particles. After washing, the cold-pressed powder exhibited a coercivity value of 11.8 kOe and a maximum magnetization of 92.0 emu/g under an applied field of 50 kOe.     

On the Dromion Interaction of the JMKP Equation: Equipotential Plots

The dromion interaction of the (3+1)-dimensional conditional integrable model, Jimbo-Miwa-Kadomtsev-Petviashvilli (JMKP) system, is re-studied by means of the equipotential surface plots. The result shows that the interaction among dromions of the JMKP system is elastic which corrects the conclusion of our previous paper (J. Math. Phys. 38 (1997) 3123). firtherrnore, the interaction is also irrotational. That is to say, there are not exchanges of any physical quantities like energy, momentum and angular momentum.     

Syntheses,Structures and Photocurrent Response Properties of Two Crystals Based on Tetrathiafulvalene Derivatives

In this paper, two compounds [Zn_2~(2+)(2,6-bis(4'-pyridyl)-TTF)(TPA)_2~(2-)](1) and [Cd~(2+)(2,6(7)-bis(4'-pyridyl)-TTF)(TPA)~(2-)(H_2O)_2](TTF = tetrathiafulvalene, TPA = terephthalic acid)(2) were synthesized by using solvothermal method and characterized by single-crystal X-ray. The purity of the two compounds was confirmed by their PXRD data. We also tested the photocurrent responses of these two compounds, and found they could generate photocurrent signal when exposed to light, but the photocurrent intensity of compound 2 is significantly greater than that of 1. From the crystal structure analysis, the possible reason for this phenomenon is that 2 has a more compact ligand arrangement than 1, leading to a higher carrier density and easier excitation.     

足球运动员服用螺旋藻对体成分、下肢爆发力以及有氧功能的影响

为了探究口服螺旋藻补剂对足球运动员体成分、下肢爆发力以及身体有氧功能的影响,用随机双盲对照实验,将20名男性足球运动员随机选出10名分配至螺旋藻组(SP组),另10名分配至安慰剂组(PB组).在训练前和为期8周训练后分别采集受试者体成分、下肢爆发力及身体有氧能力等数据,采用重复测量方差分析研究组内数据的前后差异.结果表明:8周实验结束后,PB组受试者右下肢肌肉量、纵跳高度、红细胞平均体积显著上升(P<0.05),平均血红蛋白浓度显著下降(P<0.05),其余指标变化不显著(P>0.05). SP组受试者的肌肉量、左上肢肌肉量及右下肢肌肉量、纵跳高度、纵跳最大加速度、纵跳平均输出功率、纵跳总最大功率均显著上升(P<0.05),其他指标前后无显著差异(P>0.05).表明8周螺旋藻补剂的摄入抑制了足球运动员训练氧化应激引起的负面效应,对训练适应有积极作用.     

PBAT/PVA复合材料发泡行为及抗收缩性能研究

为提高聚己二酸丁二醇酯-对苯二甲酸丁二醇酯(PBAT)发泡材料的抗收缩性,用热塑性加工的方法制备PBAT/聚乙烯醇(PVA)复合材料,并采用超临界二氧化碳技术制备发泡材料.探讨了PVA含量、发泡温度以及压力对泡孔形貌的影响.流变性能、动态力学分析的结果表明, PVA的加入改善了PBAT熔体的黏弹性,提高了其熔体强度,增强了复合材料的发泡能力.研究结果表明, PVA的加入可提高PBAT的发泡温度,降低发泡材料的收缩率.当PVA含量为10%时,可将发泡温度提高至105℃,稳定体积膨胀率为15倍,体积收缩率仅有1.25%;而此时PBAT的体积膨胀率只有7倍,体积收缩率却达到了78.83%.