Molecularly imprinted polymers on the surface of silica microspheres via sol‐gel method for the selective extraction of streptomycin in aqueous samples

Streptomycin‐imprinted silica microspheres were prepared by combining a surface molecular‐imprinting technique with the sol‐gel method. A mixture of tetrahydrofuran, ethanol, and water (6:1:1, v/v/v) was selected as dispersing solvent while 3‐aminopropyltriethoxysilane and triethoxyphenylsilane acted as functional monomers, and tetraethyl orthosilicate as a cross‐linker. Characterization of the molecularly imprinted polymers was conducted using scanning electron microscope and dynamic binding experiments. As compared to the nonimprinted polymers, the imprinted polymers exhibited a higher degree of saturated adsorption volume up to 26.3 mg/g, and better selectivity even in an aqueous solution with interfering compounds, including dihydrostreptomycin, neomycin, and tetracycline. The adsorption ability and selectivity were observed to be influenced by the mole ratio of 3‐aminopropyltriethoxysilane and triethoxyphenylsilane. Feasibility of the polymers to be used for actual application was also evaluated with spiked samples, indicating great potential for large‐scale applications. Moreover, the streptomycin‐imprinted polymers can be repeatedly used for 12 cycles without losing original performance, which is beneficial for commercial use.     

Pt/CexZr1-xO2 催化剂在含硫合成气中催化水煤气变换反应活性

 采用浸渍法制备了 Pt/Ce_xZr_1-xO₂ 催化剂, 通过 X 射线衍射和程序升温还原等方法对催化剂进行了表征, 并在固定床反应器中评价了催化剂在合成气和含硫合成气中的水煤气变换活性. 结果表明, 铈锆固溶体的氧化还原能力强于 CeO₂, Zr 的掺杂明显改善了 CeO₂ 的孔道结构, 其担载的 Pt 催化剂具有更高的金属分散度, 因而活性更高. 两种催化剂在含硫合成气中的催化活性较无硫合成气中的均有所降低, 且 H₂S 浓度越大, 催化剂活性下降越多, 但这种因吸附硫而引起的失活是可逆的, 即催化剂重新暴露在无 H₂S 重整气的还原性气氛下活性能基本恢复.     

O-羧甲基壳聚糖纳米微粒制备及对Ni~(2+)吸附研究

将壳聚糖与氯乙酸反应,通过控制反应条件制备了取代度为0.71的O-羧甲基壳聚糖,将改性后的O-羧甲基壳聚糖与多聚磷酸钠反应,制备了粒径分布在370-710nm的O-羧甲基壳聚糖纳米微粒,透射电镜观察表明该微粒呈球状,平均粒径为450nm.在此基础上研究了O-羧甲基壳聚糖纳米微粒对工业电镀镍废水Ni~(2+)吸附性能,考察了溶液pH、Ni~(2+)起始浓度、平衡吸附时间、粒径等因素的影响,结果表明:O-羧甲基壳聚糖微粒最佳吸附条件是Ni~(2+)溶液pH为8.0、Ni~(2+)溶液起始浓度为33.28mg/ml、平衡吸附时间为0.5h、粒径较小的O-羧甲基壳聚糖纳米微粒对Ni~(2+)的吸附量要大于粒径较大的吸附量.     

仪器定量分析中几个问题的探讨

详细介绍了分析方法的评价指标,包括检出限、测定限、灵敏度、精密度、准确度、动态范围和线性范围、抗干扰能力等,单因素优化方法与加标回收实验评定测定结果准确度的可靠性,并就分析工作中遇到的一些实际问题进行了讨论.     

基于透明质酸构筑的药物递送载体及其应用

传统纳米药物控释载体主要通过细胞胞吞作用实现药物递送,其主要过程为被动靶向机制,因此会影响纳米载体在肿瘤组织的富集和治疗效果.近年来生物大分子透明质酸因其优异的水溶性、生物相容性、可降解性和肿瘤靶向性备受科研工作者青睐,已被广泛用于药物控释载体的构筑中,并成为靶向肿瘤治疗纳米载体领域的研究热点.本文根据透明质酸基纳米载...     

Modeling of reinitiation ability of polymer brushes grown by surface‐initiated photoiniferter‐mediated photopolymerization

A kinetic model developed to investigate surface‐initiated photoiniferter‐mediated photopolymerization (SI‐PMP) and parameterized using experimental thickness data from SI‐PMP of methyl methacrylate is used to examine chain extension by reinitiation. Specifically, the effects of light intensity, concentration of an added deactivator, tetraethylthiuram disulfide (TED), and initial photoiniferter (PI) concentration on the reinitiation ability of surface‐tethered PMMA layers is examined in detail. The simulations show that while increases in [TED] and decreases in light intensity affect overall rates of PMMA layer growth in a similar fashion, their effect on reinitiation ability of PMMA layers is significantly different: reinitiation ability increases with increasing [TED] but it is not improved by decreases in light intensity. Simulations also suggest that polymer layers synthesized in the presence of TED have a greater tendency to form surface‐tethered block copolymers upon reinitiation compared with polymer layers synthesized without TED and at lower light intensity. While both [PI] and [TED] affect the reinitiation ability, the effect of [TED] on reinitiation ability is identical at a given [TED]/[PI] ratio for all PI and TED concentrations tested. These findings obtained from the rate‐based model are instrumental in delineating strategies for creating tethered block copolymer layers or mixed brushes by SI‐PMP. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1586–1593, 2010     

Pd-Si binary bulk metallic glass

Pd_80+x Si_20−x (x = 0, 1, and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content, the glass transition temperature T _g, the initial crystallization temperature T _x and the onset crystallization temperature T _p of Pd-Si binary glassy alloys increase. Moreover, the supercooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability, which can be greatly improved by fluxing treatment. Supported by the National Basic Research Program of China (Grant No. 2007CB613905) and the National Natural Science Foundation of China (Grant Nos. 50671050 and 50431030)     

A functionalized dianthryl tetraaza macrocycle having the recognizing and switching ability

The synthesized macrocycle L is the novel fluorescent receptor having the switching ability by the external stimuli as well as having the recognizing ability of various metal ions. In particular, this macrocycle L shows the possibility of the selectivity of metal ions even in the same charge ions of a different metal, and the values of association constant (M⁻¹) of that for metal ions are consistent with the tendency of increasing charge number of metal ion. In addition, the values of quantum yield (Φ_F) of metal complexes of macrocycle L were ranged from 0.021 to 0.111 enough to recognize the metal ions in macrocycle L. We know from the fluorescent pH titration of macrocycle L by acid/base that the change of fluorescence intersects at about pH=5.     

Study of Oxidation-Reduction Properties and NO-Donor Ability of Dienediamines in the Indole, Pyrrole, and Thiophene Series

We have conducted an electrochemical study of the oxidation-reduction properties of synthesized dienediamines: derivatives of indole, pyrrole, and thiophene. We have established that reduction of the indicated compounds occurs with successive transfer of two electrons, the first transfer being reversible. We consider the effect of structural factors and the nature of the heterocycle on the ease of reduction of the given compounds. We present the results of an initial study of the NO-donor ability of the compounds upon oxidation.