Early phase laser induced plasma diagnostics and mass removal during single-pulse laser ablation of silicon

The electron number density and temperature during the early phase (<300 ns) of laser-induced plasmas from silicon using a 266-nm, 3-ns Nd:YAG laser were deduced via spectroscopic methods. These parameters were measured as a function of delay time vs. irradiance in the range of 2–80 GW/cm², and compared with crater volume measurements. A dramatic change in plasma characteristics (electron number density, temperature, and degree of ionization) as well as a sharp increase of mass removal was observed when the irradiance was increased beyond a threshold of 20 GW/cm². Possible mechanisms such as inverse bremsstrahlung and self-regulation were used to describe these data in the low irradiance region. Laser self-focusing and critical temperature are discussed to explain the dramatic changes after the irradiance reaches the threshold.     

Adsorptive property of Cu2+–ZnO/cetylpyridinium–montmorillonite complexes for pathogenic bacterium in vitro

Cu²⁺–ZnO/cetylpyridinium–montmorillonite (Cu²⁺–ZnO/CP–MMT) complexes were prepared using montmorillonite (MMT), Cu²⁺, Zn²⁺, and cetylpyridinium (CP). The goal was to assess comparatively the adsorption properties of Cu²⁺–ZnO/CP–MMT in vitro using pathogenic Escherichia coli. The results showed that Cu²⁺–ZnO/CP–MMT adsorbed significantly (P < 0.05) more E. coli compared with the parent clay. The adsorption process of bacterial cells occurring on the modified MMT surface reached equilibrium after 90 min. The percentages of E. coli adsorbed onto the surfaces of Cu²⁺–ZnO/CP–MMT and MMT in adsorption equilibrium were 84.66% and 47.01%, respectively. Adsorption data from the bacteria-clay systems followed the Langmuir and Freundlich isotherms, but not the BET isotherm. Adsorption of E. coli in acidic medium was higher than in alkaline medium. The extent of bacteria adsorption onto the modified MMT increased with decreasing ionic strength, and with increasing temperature. The processes of E. coli adsorption onto the tested adsorbents were endothermic and spontaneous at the experimental temperature. The mechanism of adsorption of bacteria on Cu²⁺–ZnO/CP–MMT may involve enhanced hydrophobicity and the reversal of surface charge from negative to positive.     

球面卷积算子的饱和阶

本文给出了确定球面卷积算子饱和阶的一般方法并举例说明了它的应用．     

手性4-膦酸二酯基-3-卤-2(5H)-呋喃酮的合成与结构

手性呋喃酮1a-1b与亚磷酸三酯2a-2b通过串联的不对称Michael加成/分子内Michalis-Arbazov重排反应,得到了含磷官能团的新手性化合物,5-(S)-(l-孟氧基)-4-膦酸二酯基-3-卤素-2(5H)-呋喃酮4a-4d。该反应具有条件温和,产率高(86%-95%),光学纯度单一(d.e.≥98%)的特点。通过元素分析,IR,UV,^1HNMR,^1^3CNMR,MS,[α]~D^2^0波谱分析数据以及X射线四圆衍射数据确定了它们的化学结构和绝对构型。     

AEO-9体系溶致液晶性能及其组成方程

以非离子表面活性剂十二烷基醇聚氧乙烯醚(AEO-9)/正丁醇/正辛烷/水组成的四元体系为研究对象,绘制了拟三元相图。在液晶区选取样品点,拍摄纹理照片,并结合^2HNMR谱图确定了液晶类型其中主要是状液晶。利用小角X射线衍射测定了层状液晶的层间距d,得到层间距d和液晶含水量的关系。根据层状液晶结构的特点,推导出层状液晶组成方程,并对本体系进行了验证。结果表明,根据议程计算出的液晶区域的开头和位置与实验测得的相图中液晶的开头和位置基本相同,为实际应用提供了依据。     

A study of the effects of process variables on the synthesis of PZT thin films by the pyrosol process

We investigated the feasability of elaboration by the pyrosol process, on various substrates, of PZT (52/48) ferroelectric phases in thin film configuration. Changes in the deposition process, such as the introduction of multilayer techniques, as well as exand in-situ post-depositional annealing treatments, were applied in order to evaluate their impact on the composition, surface morphology and crystallinity. Under certain conditions, the perovskite phase was found to comprise up to 80% of the crystalline material in films elaborated with an in-situ annealing treatment. The primary competing phase in impure deposits was lead oxide.     

Quasi-solid medium for photoinduced charge separation

New quasi-solid was proposed as a medium for photoinduced charge separation. Photoinduced charge separation and hydrogen production with the new quasi-solid medium using polysaccharide has been investigated. The new medium is a quasi-solid polysaccharide containing a large quantity of water. This medium is tight and elastic solid, obtained by cooling an aqueous solution of a polysaccharide (agarose or κ-carrageenan in this paper) to room temperature after it was dissolved in water by heating. When the quasi-solid (agarose or κ-carrageenan) involving sacrificial electron donor ethylenediaminetetraacetate (EDTA), tris(2,2′-bipyridine)ruthenium complex ([Ru(bpy)₃]²⁺) and methylviologen (MV²⁺) was irradiated with visible light, methylviologen cation radical (MV⁺) was formed. The formation rate of methylviologen cation radical in an agarose solid was faster than that in a κ-carrageenan one. Photoinduced hydrogen production was achieved with this system containing additionally proton reduction catalyst such as platinum black (Pt black), platinum oxide (PtO₂), and ruthenium oxide (RuO₂). The characteristics of this solid medium for photochemical reactions were discussed.     

Rheological properties of styrene–butadiene rubber filled with electron beam modified surface treated dual phase fillers

The rheological properties of styrene–butadiene rubber (SBR) loaded with dual phase filler were measured using Monsanto Processability Tester (MPT) at three different temperatures (100°C, 110°C and 130°C) and four different shear rates (61.3, 306.3, 613, and 1004.5 s⁻¹). The effect of electron beam modification of dual phase filler in absence and presence of trimethylol propane triacrylate (TMPTA) or triethoxysilylpropyltetrasulphide (Si-69) on melt flow properties of SBR was also studied. The viscosity of all the systems decreases with shear rate indicating their pseudoplastic or shear thinning nature. The higher shear viscosity for the SBR loaded with the electron beam modified filler is explained in terms of variation in structure of the filler upon electron beam irradiation. Die swell of the modified filler loaded SBR is slightly higher than that of the unmodified filler loaded rubber, which is explained by calculating normal stress difference for the systems. Activation energy of the modified filler loaded SBR systems is also slightly higher than that of the control filler loaded SBR system.