A new calibration method for measuring acoustic transfer matrixes with flow and application to an automotive compressor

A new method for measuring acoustic transfer matrixes with flow has been developed. It is based on two-load technique. Great improvements were obtained on specific calibration of the connections. We present here the calibration principles and validation. Measurements of basic resonating systems, first without flow then with flow up to Mach 0.2 clearly validated the accuracy of the technique, even under extreme flow conditions.     

光谱法研究埃洛石纳米管与溶菌酶间的相互作用

以溶菌酶作为模型蛋白,主要利用光谱法研究了埃洛石纳米管与溶菌酶之间的相互作用。荧光光谱结果表明向溶菌酶体系中加入埃洛石纳米管会出现荧光猝灭现象,猝灭机理符合静态猝灭规律。共振光散射强度的增加可能与埃洛石纳米管-溶菌酶复合物的形成而导致的分子尺寸的增加有关,这与紫外-可见吸收光谱的变化和静态猝灭机理相一致。同步荧光光谱分析表明两者之间的相互作用可能发生在色氨酸所处位置附近,作用过程使溶菌酶的二级结构发生变化,分子链错误折叠,加入浓度为100mg/L和200mg/L的埃洛石纳米管时,通过圆二色谱数据计算出分别导致α-螺旋的含量降低3.28%和6.89%。     

探索金鱼图的奇优美性

给出了奇优美图和二分奇优美图的概念,并定义了金鱼图,证明了在鱼头为不同图形的情况下,金鱼图仍然是奇优美的,且是二分奇优美的.还证明了:对一个奇优美图H和一棵二分奇优美树T,用一条边连接T的一个顶点和H的标号基点u_0后所得到的金鱼图仍是奇优美图.     

Simultaneous extraction and determination of various pesticides in environmental waters

A simple and rapid method was developed for the simultaneous analysis of nine different pesticides in water samples by gas chromatography with mass spectrometry. A number of parameters that may affect the recovery of pesticides, such as the type of solid‐phase extraction cartridge, eluting solvent in single or combination and their volumes, and water pH value were investigated. It showed that three solid‐phase extraction cartridges (Strata‐X, Oasis HLB, and ENVI‐18) produced the greatest recovery while ethyl acetate/dichloromethane/acetone (45:10:45, 12 mL) followed by dichloromethane (6 mL) was efficient in eluting target pesticides from solid‐phase extraction cartridges. Different water pH values (4–9) did not show a significant effect on the pesticides recovery. The optimized method was verified by performing spiking experiments with a series of concentrations (0.002–10 μg/L) in waters, with good linearity, recovery, and reproducibility for most compounds. The limit of detection and limit of quantification of this optimized method were 0.01–2.01 and 0.02–6.71 ng/L, respectively, much lower than the European Union environmental quality standard for the pesticides (0.1 μg/L) in waters. The proposed method was further validated by participation in an interlaboratory trial. It was then subsequently applied to river waters from north‐east Scotland, UK, for the determination of the target pesticides.     

The influence of porosity of ammonium perchlorate (AP) on the thermomechanical and thermal properties of the AP/polyvinylchloride (PVC) composite propellants

The influence of porous ammonium perchlorate (P_OAP) on the thermomechanical and combustion behavior of solid rocket propellants based on polyvinylchloride binder has been investigated. Differential scanning calorimetry, differential thermogravimetry, dynamic mechanical thermal analysis, and scanning electronic microscopy measurements were used for thermomechanical and thermal decomposition properties assessment. The results obtained indicate that lower glass transitions of the propellants and catalytic effect of combustion are obtained with P_OAP.     

存在初始分布时自缩合乙烯基聚合体系的统计理论

本文利用生成函数方法对存在初始分布的自缩合乙烯基聚合反应体系进行研究．首先在任意初始分布情形下,构造并通过反应体系的微分动力学方程导出对应的生成函数．进一步分别考察了均一初始分布和混合初始分布两种情形,利用生成函数获得反应体系的数均、重均和Z-均聚合度以及多分散指数等物理量．研究结果表明,利用生成函数方法不仅可以给出超支化高分子的数量分布函数,而且可以使平均高分子物理量的计算大为简化．同时发现,反应体系的统计特征与初始分布密切相关,相应的结果可为进一步研究分批投料、多组分及非等活性等更加复杂的自缩合乙烯基反应体系提供可能的基础．     

Proton beam generation by ultra-high intensity laser–solid interaction

We report on some recent experimental results on proton production from ultra-intense laser pulse interaction with thin aluminium and plastic foil targets. These results were obtained at Laboratoire d'Optique Appliquée with the 100 TW ‘salle jaune’ laser system, delivering 35 fs laser pulses at 0.8 μm, reaching a maximum intensity on target of a few 10¹⁹ W/cm².

In such extreme interaction conditions, an intense and collimated relativistic electron current is injected from the plasma created on the laser focal spot into the cold interior of the target. Its transport through dense matter, ruled by both collisions and self-induced (electro-magnetic) field effects, is the driving mechanism for proton acceleration from the rear side of thin foils: when reaching and leaving the foil rear-side, the fast electrons create a large charge separation and a huge electrostatic field with a maximum value of few TV/m, capable of accelerating protons.

A parametric study as a function of the laser driver and target parameters indicates an optimal value for target thickness, which strongly depends on the laser prepulse duration. In our experiments, we did irradiate targets of various materials (CH, Al, Au) changing the prepulse duration by using fast Pockels cells in the laser chain. CR-39 nuclear track detectors with Al filters of different thickness and a Thomson parabola were used to detect proton generation. The best results were obtained for 2 μm Al targets, leading to the generation of proton energies with energies up to 12 MeV.     

Zirconia-supported phosphotungstic acid as catalyst for alkylation of phenol with benzyl alcohol

The liquid-phase alkylation of phenol with benzyl alcohol was carried out using zirconia-supported phosphotungstic acid (PTA) as catalyst. The catalysts with different PTA loadings (5–20 wt.% calcined at 750 °C) and calcination temperature (15 wt.% calcined from 650 to 850 °C) were prepared and characterized by ³¹P MAS NMR and FT-IR pyridine adsorption spectroscopy. The catalyst with optimum PTA loading (15%) and calcination temperature (750 °C) was prepared in different solvents. ³¹P MAS NMR spectra of the catalysts showed two types of phosphorous species, one is the Keggin unit and the other is the decomposition product of PTA and the relative amount of each depends on PTA loading, calcination temperature and the solvent used for the catalyst preparation. The catalysts with 15% PTA on zirconia calcined at 750 °C showed the highest Brönsted acidity. At 130 °C and phenol/benzyl alcohol molar ratio of 2 (time, 1 h), the most active catalyst, 15% PTA calcined at 750 °C gave 98% benzyl alcohol conversion with 83% benzyl phenol selectivity.     

Decomposition of 3′‐azido‐2′,3′‐dideoxythymidine 5′‐monophosphate (AZTMP) prodrugs in biological media studied by on‐line solid‐phase extraction coupled to liquid chromatography mass spectrometry

Using a column‐switching HPLC method previously described, we studied the behavior of some mononucleotide prodrugs (pronucleotides) of 3′‐azido‐2′,3′‐dideoxythymidine in various biological media. From UV data, this method allowed quantification of transient metabolites resulting from prodrug bioconversion. The kinetic data related to the successive steps were calculated according to pseudo‐first‐order kinetic models and optimized using mono‐ or poly‐exponential regressions. Various metabolites were identified by co‐injection with authentic samples and/or ESI‐MS coupling. The results led us to propose, for each considered pronucleotide, a global decomposition pathway ending in the selective delivery of the corresponding mononucleotide. Associated to the determination of other parameters (lipophilicity, aqueous solubility), the present study contributes to the search of suitable pharmacological properties for further in vivo evaluations. Copyright © 2009 John Wiley & Sons, Ltd.     

WINDOWS环境下输入法编程技术

本文论述了中文WINDOWS系统下输入法编程技术的基本原理、相关技术及其实现的方法.