THERMODYNAMIC STUDY ON ADSORPTION OF AROMATIC SULFONIC ACIDS ONTO MACROPOROUS WEAK BASE ANION EXCHANGER FROM AQUEOUS SOLUTIONS

 The adsorption equilibrium isotherms of three aromatic sulfonic acid compounds, 2-naphthalenesulfonic acid, p-toluenesulfonic acid and p-chlorobenzenesulfonic acid, from aqueous solutions by macroporous weak base anion exchanger within the temperature range of 293 K-313 K were obtained. Several isotherm equations were correlated with the equilibrium data, and the experimental data was found to fit the three-parameter Redlich-Peterson equation best within the entire range of concentrations. The study showed that the hydrophobicity of solute has distinct influence on adsorption capacity of the anion exchanger for the aromatic sulfonic acid. Moreover, estimations of the isosteric enthalpy, free energy,and entropy change of adsorption were also reported. The positive isosteric enthalpy and entropy change for adsorption indicate an endothermic and entropy driven process in the present study.     

多壁碳纳米管对沙林的敏感性研究

自碳纳米管被发现以来,由于其具有许多独特的电学、磁学、力学和气敏特性而引起了人们广泛的关注,在结构增强、纳米电子器件、场发射、储氢、传感器等众多领域具有非常广阔的应用前景,成为当前研究的热点之一[1,2].近年来,随着碳纳米管在传感器特别是气体检测领域研究的不断深入,碳纳米管为敏感材料的传感器已成功应用于对O2、NO2、NH3、H2等气体的检测研究[3],其中对NO2的检测可达到10×10-9(φ),但尚未见碳纳米管用于毒剂检测的报道.本文以碳纳米管作为石英晶体微天平膜材料,研究了碳纳米管的化学修饰方法及其对检测沙林的影响,结果表明经强酸加热氧化的碳纳米管对沙林响应大、解吸快、重复性好,可以作为传感器检测沙林的膜材料.该研究为碳纳米管在化学毒剂中的应用奠定了基础.     

Study of urinary nucleosides as biological marker in cancer patients analyzed by micellar electrokinetic capillary chromatography

Thirteen normal and modified nucleosides, primarily degradation products of transfer ribonucleic acid (tRNA), were evaluated as potential tumor markers for cancer patients. Their urinary concentrations were determined by means of micellar electrokinetic capillary chromatography (MEKC) in the urine from 54 healthy adults and 70 cancer patients, then quantitatively expressed as a function of creatinine excretion. It was found that urinary nucleosides for cancer patients were on the average significantly higher than those for healthy controls, however, no significant differences were found between male and female or between different ages. Based on 13 urinary nucleoside concentrations, principal component analysis (PCA) could be used to classify 72% of cancer patients from the healthy controls. The present study shows that the precise measurement of urinary nucleosides by MEKC in combining with PCA technique may provide a clinically useful approach for diagnosis of cancer.     

环境和生物样品中铂族金属的分析研究进展

评述了近年来环境和生物样品中痕量铂族金属的分析研究进展，重点介绍了样品的预处理和分离富集技术以及检测手段等。     

新型紫外衍生试剂用于D-氨基酸的毛细管电泳分离

采用一种新型紫外衍生试剂对乙酰氨基苯磺酰氟(PAABS-F)作为柱前衍生试剂,成功地对19种标准D-氨基酸和甘氨酸进行了衍生和毛细管电泳分离。详细研究了各种分离条件对毛细管电泳分离的影响。实验结果表明:采用20 mmol/L硼砂(pH 9.3),126 mmol/L十二烷基硫酸钠,8 mmol/Lβ-环糊精和20mmol/L NaC l时分离结果最佳,16 m in内实现了20种氨基酸的基线分离。     

小波包去噪信号的分形特征

将分形理论与小波包滤波相结合，用盒维数的大小来评判信号曲线的滤波情况。随着小波包分解尺度的增大，滤波后信号曲线的盒维数逐渐减小，并最后趋于稳定值。因此可以根据盒维数-分解尺度曲线来选择最佳分解尺度。对仿真含噪信号进行了滤波实验，结果表明：即使在信噪比低至0．5时仍能得到较好的结果，并且该法用于毛细管电泳实验数据的处理结果同样令人满意。     

超声条件下溶胶-凝胶法制备CaSiO3:(Pb,Mn)发光材料的研究

采用溶胶-凝胶法并辅以超声技术制备了CaSiO3: (Pb,Mn)发光材料,对合成物运用荧光光谱、DTA-TG、XRD、FTIR、TEM等手段进行了表征.研究了制备时的物料配比、超声时间及焙烧温度对样品发光强度的影响,找到了最佳的合成条件.结果表明,所得样品其荧光强度约为高温固相法样品的2倍,平均粒径则降低约300 nm.     

Study of the interaction of Zn^2＋ with Aβ（10-21） by fluorescamine assay

Zinc may play a role as a co-factor in the pathogenesis of Alzheimer's disease(AD)through influencing the conformation and neurotoxicity of amyloidβ-protein(Aβ).Using the fluorescamine assay,we show for the first time that Zn~(2 )induced Aβ(10-21) aggregate in a concentration-dependent manner.These results indicate that Aβ(10-21)can be used as an in vitro model in Zn~(2 )- induced Aβaggregation and that the region 10-21 to be the minimal fragment of zinc-binding domain of full length Aβ(1-42).     

Using NaCl particles as porogen to prepare a highly adsorbent chitosan membranes

Macroporous chitosan membranes were prepared by using NaCl particles porogen and genipin as cross-linking agent. For characterization and sorption behavior comparison, other genipin cross-linked chitosan membranes were prepared by either freeze drying or by using silica particles as porogen. The mean pore diameter, the porosity, the crystallinity index (CrI) as well as the effect of the drying procedures of these chitosan membranes were examined. NaCl reduced the CrI of the chitosan membrane. The oven drying (OD) procedure decreased the mean pore diameter, the porosity, and increased the CrI of the chitosan membranes when compared with the vacuum drying (VD) procedure. The heat treatment of chitosan membrane in aqueous NaOH to attract silica porogen increased the CrI of the membrane. Under the same conditions, the membranes prepared with NaCl had better sorption performance on RR 189 and Cu²⁺ than other membranes. The maximum sorption capacity (q_e) reached 1836.17 mg RR 189/g chitosan and 151.98 mg Cu²⁺/g chitosan. The pore diameter (d_pore) of the membranes was much larger than the diameter of the adsorbate molecules (d_adsorbate), such that the ratio of d_pore/d_adsorbate had little influence on q_e. The porosity and the amorphous extent of the membranes were almost the same on q_e. When using tyrosinase catalyzing, the hydrocaffeic acid (HCA) grafted on the NaCl treated chitosan membrane was almost 10 times more than on chitosan beads. The chitosan membrane prepared with NaCl can be used as a good adsorbent with high loading capacity for implanting molecules (such as ligands, enzymes, etc.) on.