High temperature resistance studies of thin nickel foils exposed to hydrogen and oxygen

Resistance measurements were performed on thin nickel foils exposed to argon-oxygen gas mixtures at elevated temperatures. The resistance initially increased very rapidly then at oxygen pressures less than 0.08 atm, the resistance change decreased substantially before slowly increasing. At higher oxygen pressures no decrease in the resistance change occurred. These results are interpreted in light of hydrogen-oxygen-nickel interactions which occur as a result of hydrogen dissolution in nickel prior to oxidation The hydrogen originates from long-term hydrogen anneals prior to the oxidation.     

Solubility and diffusivity of organotin stabilizers in non-plasticized PVC

The kinetics of diffusion and equilibrium concentration of ten organotin stabilizers have been studied, at 100°, in non-plasticized PVC. The solvating role of the ester groups, especially when they are intramolecularly coordinated to the tin atom, is clearly indicated. No correlation has been found between the penetrant molar volume and its diffusivity, which seems largely governed by the polymer stabilizer interaction.     

Dipropylacetamide and diethylacetamide conformations in chloroform solutions as observed from lanthanide induced NMR shifts

The conformation of diethylacetamide, (C₂H₅)₂ CHCONH₂, and dipropylacetamide, (C₃H₇)₃ CHCONH₂, in solution in CDCl₃, are studied from NMR spectra observed in the presence of europium and ytterbium chelates, Eu (fod)₃ and Yb (fod)₃. The ¹H and ¹³C induced shifts are interpreted using classical energy calculations, they are found to reflect a mixture of two or three conformations. The crystalline conformation observed in derivatives of these compounds is found to be identical to the most probable one in solution.     

Non-Newtonian fluid flow around a Y-shaped fin embedded in a square cavity

Journal of Thermal Analysis and Calorimetry - This study investigates the free convection of Casson fluid inside a square cavity with intruded Y-shaped fin at the bottom surface. The Casson fluid...     

压缩双裂纹和单裂纹圆孔板应力强度因子公式

从理论模型和数值分析上澄清了国外文献关于压缩双裂纹圆孔板(double cleavage drilled compression,DCDC) 的应力强度因子不同的公式引起的混淆. 证明Plaisted 等用修正压缩无限大板中圆孔双边裂纹的解和欧拉-伯努利梁理论得到的DCDC 应力强度因子公式都存在推导和原理性的失误. 指出Jenne 等推导的公式形式过于复杂不便使用, 而He 等的公式适用范围偏小. 通过拟合有限元法宽范围数值计算结果导出DCDC 的应力强度因子的新公式, 该公式形式简单, 对无量纲裂纹长度和无量纲板宽度适用范围较大, 最大误差是7%. 此外, 还对新提出的压缩单裂纹圆孔板(single cleavage drilled compression, SCDC)做了分析, 首次得到的SCDC应力强度因子公式的最大误差是5%. 给出的2 个公式可分别用于脆性材料DCDC 或SCDC 试样的断裂韧度测试.     

Sonochemical fabrication of edible fragrant antimicrobial nano coating on textiles and polypropylene cups

We report on a simple and effective ultrasound-assisted deposition of vanillin nanoparticles (∼50 nm in size), raspberry ketone (RK) nanoparticles (∼40 nm in size) and camphor nanoparticles (width ∼30 nm, length ∼40 nm in size) on textiles and on polypropylene surfaces. The excellent antibacterial and antifungal activity of the fragrant coatings on cotton bandages, and polypropylene surface against Escherichia coli (E. coli), Salmonella paratyphi A (S. paratyphi A) and the yeast Candida albicans (C. albicans) cultures was demonstrated. It is worth pointing out that these fragrant materials are edible, making them very useful for packaging. The mechanism of the edible fragrant coating formation and adhesion to the textile was discussed, and finally an up-scaling of the sonochemical process for textile coating was carried out.     

Discrete simulation and micromechanical analysis of two-dimensional saturated granular media

In this study, a novel approach to incorporate the pore water pressure in the discrete element method (DEM) to comprehensively model saturated granular media was developed. A numerical model was constructed based on the DEM by implanting additional routines in the basic DEM code; pore water pressure calculations were used with a two-dimensional (2D) model to simulate the undrained behavior of saturated granular media. This model coupled the interaction of solid particles and the pore fluid in saturated granular media. Finally, several 2D undrained shear tests were simulated. The test results showed that the model could predict the response of the saturated granular soil to shear loading. The effect of initial compaction was investigated. Biaxial tests on dense and loose specimens were conducted, and the effect of the initial density on the change in shear strength and the volume change of the system was investigated. The overall behavior of loose and dense specimens was phenomenologically similar to the real granular material. Constant volume tests were simulated, and the results were compared to those from the coupled model. Induced anisotropy was micromechanically investigated by studying the contact force orientation. The change in anisotropy depended on the modeling scheme. However, the overall responses of the media obtained using the coupled and constant volume methods were similar.     

α-Metallated vinyl carbanionoids: III. Reactions of α-triorganostannylvinyllithiums with group IVB organometallic halides: Formation of α-trimethylplumbylvinyllithiums

Reactions of α-stannylvinyllithiums RR′CC(Li)SnMe₃ with halides Me₃MCl (M = Si, Ge, Pb) give the corresponding mixed bis(trimethylmetal)alkenes RR′CC(SnMe₃)₃. With two equivalents of methyllithium and trimethyllead chloride, RR′CC(SnMe₃)₂ can be converted to RR′CC(PbMe₃)₂. The latter, as well as RR′CC(SnMe₃)PbMe₃, undergoes transmetallation with methyllithium to give α-plumbylvinyllithiums RR′CC(Li)PbMe₃ which are more stable and apparently less basic than the corresponding α-stannyl anions.Multinuclear NMR data for the anionic species are presented and discussed.     

Photoresponse of a miniaturized metal film bolometer to ultrashort mid- and far-infrared laser pulses

We report on an investigation of a photoresponse induced in a novel, miniaturized low-noise metal resistor film bolometer when irradiated by ultrashort laser pulses (duration 100 ps to 200 ns) with wavelengths covering the mid- and far-infrared spectral ranges. Successful operation at room temperature was achieved and almost constant detectivity was found over the whole frequency range investigated (15–1100 cm⁻¹). The minimum detectable laser pulse energy was determined to be about 0.6 μ J (with an electronic bandwidth of 1 kHz). This high detectivity and the miniaturized dimensions afford the possibility of building detector arrays applicable in mid- and far-infrared spectroscopy.