Folate-targeted optical and magnetic resonance dualmodality PCL-<Emphasis Type="Italic">b</Emphasis>-PEG micelles for tumor imaging

A biodegradable tumor targeting nano-probe based on poly（ε-caprolactone）-b-poly（ethylene glycol）block copolymer（PCL-b-PEG）micelle functionalized with a magnetic resonance imaging（MRI）contrast agent diethylenetriaminepentaacetic acid-gadolinium(DTPA-Gd³⁺)on the shell and a near-infrared（NIR）dye in the core for magnetic resonance and optical dual-modality imaging was prepared.The longitudinal relaxivity（r₁）of the PCL-b-PEG-DTPA -Gd³⁺micelle was 13.4（mmol/L）^-1s^-1,three folds of that of DTPA-Gd³⁺,and higher than that of many polymeric contrast agents with similar structures.The in vivo optical imaging of a nude mouse bearing xenografted breast tumor showed that the dual-modality micelle preferentially accumulated in the tumor via the folic acid-mediated active targeting and the passive accumulation by the enhanced permeability and retention（EPR）effect.The results indicated that the dualmodality micelle is a promising nano-probe for cancer detection and diagnosis.     

固相微萃取高效液相色谱法测定食品中己烯雌酚

建立了固相微萃取(SPME)-高效液相色谱(HPLC)联用测定食品中己烯雌酚(DES)的方法.考察了萃取纤维头、萃取时间、解吸时间和盐的添加对萃取效果的影响.在此基础上,采用正交试验,以解析液组成、萃取液pH和搅拌速度为3因素筛选出了最佳固相微萃取条件.该分析方法的线性范围为0.02 ～2.0μg/ml,工作曲线线性良...     

Structure and wettability relationship of coelectrospun poly (L‐lactic acid)/gelatin composite fibrous mats

Coelectrospun polylactide(PLA)/gelatin (GE) composite fibrous matrixes have been identified to exhibit much improved performances compared to the respective components; however, the reasons for their water contact angles decreasing to zero at proper PLA/GE ratios remain unclear. To get a deep understanding of the phenomenon, PLA and GE were coelectrospun with different PLA/GE ratios in this study. Although the resulting composite fibers were homogeneous in appearance, they were detected different microscopic structures by transmission electron mircroscope (TEM) and via morphological observations after selective removal of either PLA or GE component. Together with the results of degradation study in phosphate buffered solution, a kind of cocontinuous phase separation microstructure could be identified for the PLA(50 wt%)/GE(50 wt%) composite fibers, which also showed the water contact angle of 0°. This value was far lower than those of electrospun PLA (～123°) and GE (～42°) fibrous matrixes. The X‐ray photoelectron spectrometry (XPS) data revealed that the polar side groups of protein macromolecules have moved toward composite fiber surface with solvent evaporation during electrospinning, due to the hydrophobic interaction between PLA and GE. Then the excellent hydrophilicity of PLA(50 wt%)/GE(50 wt%) composite fibers could be suggested as the consequence of: (1) the cocontinuous phase separation structure could provide more interface and void for water molecules penetrating; and (2) the accumulation of polar groups on composite fiber surface significantly increased the surface wettability. Copyright © 2010 John Wiley & Sons, Ltd.     

Perchlorate removal by granular activated carbon coated with cetyltrimethyl ammonium bromide

In this study, granular activated carbon (GAC) coated with cetyltrimethyl ammonium bromide (CTAB) (GAC-CTAB) was synthesized to remove perchlorate from water via adsorption. Laboratory-scale batch experiments were performed to study the factors affecting the perchlorate adsorption by GAC-CTAB, including the CTAB content and solution pH, and explore the mechanisms behind the adsorption phenomenon. The novel GAC-CTAB material was characterized by scanning electron microscopy (SEM), zeta potential measurement and Brunauer-Emmett-Teller (BET) analysis. The characterization tests showed that CTAB was deposited on the GAC surface, pH(pzc) of the material was between 2.0 and 3.0, and the BET specific surface area was reduced from 925 to 729 m(2)/g with the increasing CTAB content from 0 to 0.034 mmol CTAB/g GAC. The adsorption process was better described by a pseudo-second-order kinetics model and the Freundlich adsorption model. The CTAB content and solution pH significantly influenced the kinetics and chemical equilibrium of the adsorption. When the CTAB content was increased from 0.0.023 to 0.135 mmol CTAB/g GAC, the K in the Freundlich adsorption isotherm increased from 0.071 to 0.19 mmol/g. The optimal adsorption typically occurred at pH 2-3, close to the pH(pzc) of the solution. Finally, the mechanisms for the adsorption of perchlorate on GAC-CTAB were associated with surface complexation, electrostatic interaction and ion exchange.     

差压变送器在监测系统中的应用及故障处理

简单介绍了差压变送器的工作原理,设计出一套采集系统,利用北京鼎升力创R8000系列模块和差压传感器的配合来完成对数据的采集。并对R8000系列模块、差压变送器、引压管、变频干扰等在使用过程中的常见故障进行分析,提出解决方法。     

An on-line remote supervisory system for microparticles based on image analysis

A new on-line remote particle analysis system based on image processing has been developed to measure microparticles. The system is composed of particle collector sensor (PCS), particle image sensor (PIS), image remote transmit module and image processing system. Then some details of image processing are discussed. The main advantage of this system is more convenient in particle sample collection and particle image acquisition. The particle size can be obtained using the system with a deviation abot less than 1 mm, and the particle number can be obtained without deviation. The developed system is also convenient and versatile for other analyses of microparticle for academic and industrial application.     

Potential Hydrothermal-Humification of Vegetable Wastes by Steam Explosion and Structural Characteristics of Humified Fractions

In this work, steam explosion (SE) was exploited as a potential hydrothermal-humification process of vegetable wastes to deconstruct their structure and accelerate their decomposition to prepare humified substances. Results indicated that the SE process led to the removal of hemicellulose, re-condensation of lignin, degradation of the cellulosic amorphous region, and the enhancement of thermal stability of broccoli wastes, which provided transformable substrates and a thermal-acidic reaction environment for humification. After SE treatment, total humic substances (HS), humic acids (HA_s), and fulvic acids (FA_s) contents of broccoli samples accounted for up to 198.3 g/kg, 42.3 g/kg, and 166.6 g/kg, and their purification were also facilitated. With the increment of SE severity, structural characteristics of HA_s presented the loss of aliphatic compounds, carbohydrates, and carboxylic acids and the enrichment of aromatic structures and N-containing groups. Lignin substructures were proved to be the predominant aromatic structures and gluconoxylans were the main carbohydrates associated with lignin in HA_s, both of their signals were enhanced by SE. Above results suggested that SE could promote the decomposition of easily biodegradable matters and further polycondensation, aromatization, and nitrogen-fixation reactions during humification, which were conducive to the formation of HA_s.     

风机封闭系统内噪声模拟分析

风机系统工作时的一个突出问题是其进风口和出风口产生的噪声。由于风机流场非常复杂,以及实验成本、实验条件限制,基于计算流体力学（Computational Fluid Dynamics, CFD）的理论逐渐成为风机噪声估计的重要方法。本文拟通过对由风机及其冷却系统构成的封闭系统进行数值建模和仿真,判断出风机主要气动噪声源的位置和种类,为处于封闭系统内的风机的噪声大小预测,提供一个可供参考的信息。结果表明：风机出口腔体内部非定常压力波动强度最大。     

一类具有Markov性质的混沌系统的构造

本文构造了一类具有Markov性质的分段扩张线性映射, 计算表明其具有正的李雅普诺夫指数. 通过理论分析, 证明了其极限分布是均匀分布, 并给出了其最小周期的计算公式. 通过分析符号熵测度应用于此系统时的具体涵义, 指出该系统的复杂度与系统的最小周期之间存在着矛盾关系, 说明了此系统具有可控的复杂度并给出了其复杂度随系统参数变化时的理论极限公式. 通过统计测试和复杂度测试表明, 此系统产生的混沌序列服从均匀分布, 而通过参数的调整该系统的符号熵可以接近其理论极限, 而与Logistic映射和斜帐篷映射的基于近似熵和符号熵的对比实验可知, 本文所提系统具有更高的复杂度, 并有更长的最小周期. 这表明此系统比较适合用于构造保密通信系统. 关键词： 混沌 Markov性质 复杂度 均匀分布     

高压下β-FeOOH纳米固体结构转变的研究

 以化学水解法合成的β-FeOOH纳米微粉（平均粒径在12 nm左右）为原料，分别在0.0~4.5 GPa和200~350 ℃的压力和温度范围进行冷压和热压处理。实验结果表明，冷压对β-FeOOH纳米固体的结构没有明显影响，但却使它的热致相变（从β-FeOOH相到α-Fe₂O₃相）温度从常压下的203.8 ℃提高到4.5 GPa压力下的274 ℃，接近常规体相材料的相变温度。而在一定的热压条件处理下，首次发现了从β-FeOOH相到α-FeOOH相的结构转变，并在4.5 GPa、200 ℃的热压条件下得到了转变过程中的一个新的亚稳相。从压力和温度对纳米微粒的作用角度，对上述实验结果进行了讨论。