An Au-nanoparticle decorated Sr0·76Ce0·16WO4 photocatalyst for H2 evolution under visible-light irradiation

Photocatalytic production of H₂ from water based on semiconductors is a process without the consumption of fossil energy. The development of ideal photocatalyst is a challenge that limited the application of photocatalytic technology. Here, we report a stable Sr_0·76Ce_0·16WO₄ photocatalyst for H₂ evolution under visible-light irradiation, which was synthesized via a simple high-temperature solid-state method. The composition and crystal structure of this photocatalyst was identified by X-ray Diffraction, transmission electron microscope, and X-ray photoelectron spectroscopy. The scanning electron microscopy image indicates the sample compose of micrometer particles. The bandgap of the compound was estimated to be 3.18 eV, which is significantly smaller than that of pristine SrWO₄ (4.87 eV) by the incorporation of Ce³⁺. In this experiment, the nanosized Au cocatalyst was loaded on the photocatalyst via the photodeposition method to improve the photocatalytic performances. Photocatalytic experiments revealed that photocatalytic H₂ evolution rates of Sr_0·76Ce_0·16WO₄-1.5Au sample are 45.5 μmol/h/g and 28.7 μmol/h/g in 5 vol% triethanolamine aqueous solution under simulated sunlight and visible-light irradiation, respectively, which are 1.44 times and 4.63 times higher than the cocatalysts-free one. Moreover, the apparent quantum yield of Sr_0·76Ce_0·16WO₄-1.5Au is 0.09% at 450 nm.     

纯铜深层渗铝固溶时效的组织及性能

为了提高冶金设备用铜质传热零部件的耐磨性和抗氧化性能,对纯铜进行了925℃深层渗铝12h 925℃固溶1.5h 300℃时效处理3 h,研究了其金相组织特征及其耐磨性和抗热疲劳性能.试验结果表明:处理后试样表层组织主要由β'相组成,与纯铜试样相比,其磨粒磨损抗力和粘着磨损抗力分别是纯铜的2.12倍和22.59倍,930℃循环加热冷却250次后,其热疲劳质量损失率仅为纯铜的9%.     

The blend modification of EVA-150/ starch and controlled-release of imazethapyr

The EVA-150 and starch were extruded by extruding press and the bio-degradation composite material was prepared to use as the controlled-release matrix of imazethapyr. The compatibility and crystallinity of EVA-150/starch blending were analyzed by SEM and DSC, and the controlled-released performance of imazethapyr in the carriers was also investigated by UV analysis. The results show that EVA-150/starch composite matrix has the obvious controlled-released function and the release rates of imazethapyr all exceed 50% in the environment of pH4, pH7, or pH9 after nine days. Supported by the Enterprise Postdoctoral Fund of Liaoning Province(BSH2005921077)     

Distribution of SiCp in Al and Al-Cu Alloy Centrifugally Cast with Electromagnetic Stirring

The SiCp/(AI-Cu) alloy and pure Al matrix composites have been prepared by the centrifugal casting with electromagnetic stirring. There are two particle-depleted zones formed in the samples without electromagnetic stirring. Electromagnetic stirring may result in a homogeneous distribution of fine SiC particles in the AI-Cu alloy, whereas it has little effect on the segregation in pure Al matrix. The results also show that the particle segregation is influenced by particle size and the coarse particles are more readily segregated than the fine ones.     

电磁振荡对铝硅合金凝固组织的影响

研究了直流磁场与交流电同时作用下的Al-Si过共晶合金的凝固组织的变化.试验结果表明,电磁振荡可明显细化合金的宏观组织和显徽组织,随着电磁压力的增加,宏观晶粒尺寸逐渐减小,并且共晶硅相间距减小.     

喷射沉积Al-17Si-5Fe-2Mn-2Ni-3.5Cu-1Mg-1V合金的组织及性能

采用喷射沉积快速凝固技术制备了Al-17Si-5Fe-2Mn-2Ni-3.5Cu-1Mg-1V合金,利用金相、X射线衍射和SEM等测试方法分析了合金的组织特征、热稳定性及力学性能。结果表明：喷射沉积合金的组织由大量弥散分布的粒状相、少量块状相和共晶基体组成。挤压态合金经300℃不同时间加热后,初晶Si相没有明显的粗化,热稳定性良好;合金经热挤压后,室温极限拉强度达232.2 MPa,经T6热处理后极限抗拉强度提高了17%,达271.3 MPa。     

手性烯唑醇为活性组分的杀菌聚合物的合成

以杀菌剂烯唑醇（Ⅰ）为底物，（-）-孟氧基乙酸为拆分试剂进行手性拆分，得到具有高杀菌活性的（R）-（E）-1-（2，4-二氯苯基）-2-（1，2，4-三唑-1-基）-4，4-二甲基-1-戊烯-3-醇（Ⅱ）。Ⅱ与丙烯酰氯反应生成了具有生物活性的可聚合单体（R）-（E）-1-（2，4-二氯苯基）-2-（1，2，4-三唑-1-基）-4，4-二甲基-1-戊烯-3-醇丙烯酸酯（Ⅲ），Ⅲ经自聚或与丙烯酸或甲基丙烯酸甲酯共聚制得了杀菌聚合物（Ⅳ，Ⅴ，Ⅵ），并进行聚合物活性组分的水解释放实验。总体上，在碱性介质中聚合物的活性组分水解释放速率大于在中性或弱酸性介质中的。Ⅳ和Ⅵ活性组分水解释放速率很低，而聚合物Ⅴ，随时间的延长，有大量的活性组分释出，初始释出质量浓度也较高，符合农用杀菌剂的速效性和持效性的要求，有实用意义。     

The double torsion loading configuration for fracture propagation: an improved methodology for the load-relaxation at constant displacement

For most materials the dynamics of subcritical crack propagation during stress-corrosion can be described uniquely by a relationship between the mode-I stress intensity factor K_I and the crack velocity v that generally has the form of a power law. In last 30 years, the double-torsion load-relaxation test has shown to be the most reliable method for measuring such a relation. The standard analysis, developed by Evans (J Mater Sci 1972;7:1137–46), is based on an analytical approxatimation that fails to accurately describe the specimen compliance outside a narrow region in the center of the specimen. This paper deals with the implications on data inversion of the exhaustive three-dimensional finite-element analysis recently performed by Ciccotti (J Am Ceram Soc 2000, in press) on double-torsion specimens. The results are presented in terms of corrective coefficients to the classical analytical approximation. A full methodology is developed for the numerical implementation of such corrections. By numerically simulating some relaxation tests, the classical analysis based on the analytical approximation is shown to generally underestimate the stress-corrosion index up to 30% even if the most conservative operational constraints are satisfied. On the contrary, the operational constraints can be comfortably relaxed as a consequence of the capability of correcting the finite size effects in relation to the different experimental parameters.     

Photostability of phenothiazinyl-substituted ethylenes

Photostability of phenothiazinyl-substituted ethylenes in both solution and in solid state (thin films) was investigated as a function of UV exposure time. Fluorescence intensity and spectral variation measurements in the presence and absence of ambient air were used to determine the effect of oxygen on the degradation of the compounds. The observed reduction in the fluorescence efficiency of air-saturated solutions and thin films subjected to UV was attributed to permanent photo-oxidative degradation. Photostability was higher in the cases of molecules that contained two bulky phenothiazinyl groups as compared to those containing only one phenothiazinyl group and a smaller phenyl substituent. Fully reversible fluorescence intensity decay in the degassed phenothiazine solutions was attributed to photo-isomerization, whereas the partially reversible changes in fluorescence intensity that were observed for films in the absence of air were ascribed to both photoexcited carrier capture by deep-traps acting as exciton quenching centres and degradation imparted by UV-induced bond scission.     

Novel organic–inorganic poly (3,4-ethylenedioxythiophene) based nanohybrid materials for rechargeable lithium batteries and supercapacitors

Synthesis and characterization of poly (3,4-ethylenedioxythiophene) (PEDOT) interleaved between the layers of crystalline oxides of V and Mo is discussed with special emphasis on their application potential as electrodes for rechargeable Li batteries and supercapacitors. The expansion of the interlayer spacing of crystalline oxides (for example, V₂O₅ causes expansion from 0.43 to 1.41 nm) is consistent with a random layer stacking structure. These hybrid nanocomposites when coupled with a large-area Li foil electrode in 1 M LiClO₄ in a mixture of ethylene and dimethylcarbonate (1:1, v/v), give enhanced discharge capacity compared to pristine oxides. For example a discharge capacity of ∼350 mAh g⁻¹, in the potential range 4.2–2.1 V (versus Li⁺/Li) is obtained for PEDOT–V₂O₅ hybrid which is significantly large compared to that for simple Li-intercalated V₂O_5. The improvement of electrochemical performance compared with that of pristine oxides is attributed to higher electric conductivity, enhanced bi-dimensionality and increased structural disorder. Although these conducting polymer-oxide hybrids delivered more than 300 mAh g⁻¹ in the potential range 1.3–4.3 V, their cycle life needs further improvements to realize their commercial potential. Similarly, the double layer capacitance of MoO₃ increases from ∼40 mF g⁻¹ to ∼300 F g⁻¹ after PEDOT incorporation in the interlayer gap of MoO₃ under similar experimental conditions and the nanocomposite displays intriguing effects with respect to electrochemical Li⁺ insertion. The PEDOT–MoO₃ nanocomposite appears to be a promising electrode material for non-aqueous type supercapacitors.