基于空化辐射噪声的检测方法实验研究

空化空蚀严重影响水利设备的正常工作和使用寿命,为此本文研究了基于水听器信号的水泵空化检测方法,从空化噪声辐射基本特性出发,分析并选取强度、脉冲以及频谱结构等特征参数组成最优分类特征向量,使其既有较强的稳定性,也有较好的灵敏度。以此特征向量训练获得的支持向量机(SVM)分类器进行水泵空化状态识别准确率平均能有99.6%。检测其他结构水泵的空化,识别准确率也在96.5%以上。在较高环境噪声单一能量特征无法识别的情况下,依然有较好的识别准确率。表明该方法对不同结构的水泵及较高环境噪声具有一定的鲁棒性,有较好的应用价值。     

指数型谐振管内非线性声场的模拟研究

采用气体动理学方法模拟研究五种不同驱动强度下,=0的圆直热声谐振管和=2 2的指数型热声谐振管内的非线性声场特征。研究发现:指数型管能抑制激波及声饱和现象,但管内会出现尖峰现象。尖峰处的压力波形发生了畸变;它们是非线性的能量传递与各种耗散的竞争过程中产生的不同形态的波特征;当活塞驱动位移幅值400μm时,指数型管内压力振幅增长速度明显下降。     

High‐speed countercurrent chromatography isolation of flavans from Ixeris chinensis and their identification by NMR spectroscopy

High‐speed countercurrent chromatography, combined with macroporous resin chromatography were applied to the separation and purification of flavans from Ixeris chinensis. Four flavans, namely, 5‐methoxy‐7,4′‐dihydroxyflavan‐3‐ol ( 1 ), 5,7‐dimethoxy‐4′‐hydroxyflavan‐3‐ol ( 2 ), 5,7‐dimethoxy‐4′‐hydroxyflavan ( 3 ), and 5,7‐dimethoxy‐8‐methyl‐4′‐hydroxyflavan ( 4 ), were obtained from I. chinensis for the first time. Their chemical structural identification was carried out by spectroscopic methods, including 1D and 2D NMR spectroscopy. Amounts of 13.2 mg of compound 1 , 6.4 mg of compound 2 , 5.8 mg of compound 3 , and 14.5 mg of compound 4 were separated from 120 mg 75% ethanol fraction. The purities of 1 – 4 were 99.1, 99.2, 97.3, and 98.6 %, respectively.     

过硫酸铵引发衣康酸与苎麻纤维接枝共聚反应的研究

以过硫酸铵为引发剂,使衣康酸与苎麻纤维接枝共聚,对反应条件进行了探讨,并对接枝纤维对金属离子的吸附性能进行了初步研究. 结果表明,在过硫酸铵浓度3×10- 2 m ol/L、衣康酸浓度1.80 m ol/L、外加酸浓度1.0 m ol/L、50℃下反应72 h,接枝率较高;经衣康酸接枝的苎麻纤维具有一定的离子吸附能力.     

Ionic liquid‐based microwave‐assisted extraction for the determination of flavonoid glycosides in pigeon pea leaves by high‐performance liquid chromatography‐diode array detector with pentafluorophenyl column

In this study, an ionic liquid‐based microwave‐assisted extraction (ILMAE) followed by high‐performance liquid chromatograph y ‐diode array detector with a pentafluorophenyl column for the extraction and quantification of eight flavonoid glycosides in pigeon pea leaves is described. Compared with conventional extraction methods, ILMAE is a more effective and environment friendly method for the extraction of nature compounds from herbal plants. Nine different types of ionic liquids with different cations and anions were investigated. The results suggested that varying the anion and cation had significant effects on the extraction of flavonoid glycosides, and 1.0 M 1‐butyl‐3‐methylimidazolium bromide ([C4MIM]Br) solution was selected as solvent. In addition, the extraction procedures were also optimized using a series of single‐factor experiments. The optimum parameters were obtained as follows: extraction temperature 60°C, liquid–solid ratio 20:1 mL/g and extraction time 13 min. Moreover, an HPLC method using pentafluorophenyl column was established and validated. Good linearity was observed with the regression coefficients (r²) more than 0.999. The limit of detection (LODs) (S/N = 3) and limit of quantification (LOQs) (S/N = 10) for the components were less than 0.41 and 1.47 μg/mL, respectively. The inter‐ and intraday precisions that were used to evaluate the reproducibility and relative standard deviation (RSD) values were less than 4.57%. The recoveries were between 97.26 and 102.69%. The method was successfully used for the analysis of samples of pigeon pea leaves. In conclusion, the developed ILMAE‐HPLC‐diode array detector using pentafluorophenyl column method can be applied for quality control of pigeon pea leaves and related medicinal products.     

Spectral method for vorticity‐stream function form of Navier–Stokes equations with slip boundary conditions

In this paper, we propose a spectral method for the vorticity‐stream function form of the Navier–Stokes equations with slip boundary conditions. The numerical solutions fulfill the incompressibility and the physical boundary conditions automatically. The stability and convergence of the proposed methods are proven. Numeric results demonstrate the efficiency of suggested algorithm. Copyright © 2011 John Wiley & Sons, Ltd.     

Asymmetrically Functionalized,Four‐Armed,Poly(ethylene glycol) Compounds for Construction of Chemically Functionalizable Non‐Biofouling Surfaces

Asymmetrically functionalized, four‐armed, Tween 20 derivatives that formed stable monomolecular films on solid substrates were designed and synthesized. Thiol‐modified Tween 20 was used for forming self‐assembled monolayers (SAMs) on gold, and maleimide‐modified Tween 20 was introduced onto SiO₂ surfaces with SAMs of (3‐mercaptopropyl)trimethoxysilane through Michael addition. These structurally modified Tween 20 compounds gave the original characteristics of Tween 20, non‐biofouling (from ethylene glycol groups) and functionalizable (from OH groups) properties, to each substrate. The non‐biofouling properties of the Tween 20‐coated gold and SiO₂ surfaces were investigated by surface plasmon resonance spectroscopy and ellipsometry, and these surfaces showed strong resistance against nonspecific adsorption of proteins. In addition, the biospecific binding of streptavidin was achieved after coupling of (+)‐biotinyl‐3,6,9‐trioxaundecanediamine onto the non‐biofouling surfaces through amide‐bond formation.     

荧光法研究司帕沙星与白蛋白的作用

本文用荧光光谱法、分光光度法研究了水溶液中喹诺酮类药物司帕沙星与牛血清白蛋白 (BSA)、鸡蛋白 (CEA)的相互作用 ,求得它们间的结合常数为K鸡 =8 2 9× 10 6,K牛 =4 41× 10 7;结合位点数分别为n鸡=0 5 88,n牛 =0 793,并根据F rster非辐射能量转移机制 ,测定了司帕沙星与两种血清白蛋白相互结合时其给体 受体间距离 (R鸡 =1 99nm ,R牛 =2 0 9nm)和能量转移效率 (E鸡 =0 76 6 ,E牛 =0 714)。实验表明 ,随着温度升高 ,BSA及CEA的猝灭曲线斜率降低 ,证实了司帕沙星与BSA和CEA的相互结合作用为单一的静态猝灭过程 ,其作用机制属能量转移机制。通过两种血清白蛋白与抗菌药物司帕沙星结合反应 ,探讨了药物司帕沙星在生物体内与蛋白质的相互作用的生物学效应及其作用机理。     

石墨炉原子吸收光谱法测定中成药中砷,铅

本文以HNO3 HClO4 为氧化剂 ,压力消解处理样品 ,氯化钯作测砷基体改进剂 ,磷酸氢二铵作测铅基体改进剂 ,考察了基体改进剂用量、灰化温度、原子化温度以及干扰元素对测定的影响 ,在最佳测定条件下 ,用石墨炉原子吸收光谱法测定了中成药中砷和铅 ,砷和铅测试结果分别为 :线性范围为 0～ 30 0ng·mL-1和 0～ 80ng·mL-1,检测限 3 75ng·mL-1和 1 8ng·mL-1,灵敏度 9 3ng·mL-1和 2 6ng·mL-1,平均回收率 95 7%和99 6 %。方法简单 ,灵敏度高 ,重现性好。     

白光LED面阵及其主要参数指标

本文主要利用白光LED单管制备了白光LED面阵,将制备的白光LED面阵与日亚公司的同类产品进行了对比。研究了不同电流条件下,亮度、流明效率、色坐标和显色指数的变化。