Au@SiO_2中空微球的制备及催化性能

以天然高分子阿拉伯树胶(AG)为还原剂和稳定剂制备了金纳米粒子;将含有金纳米粒子(Au NPs)、阿拉伯树胶和氨水的溶液滴加到乙醇中形成AG-Au NPs复合胶团;利用正硅酸乙酯水解,在AG-Au NPs表面包覆二氧化硅壳层;通过简单水洗的方法得到了金纳米粒子@二氧化硅(Au@SiO_2)中空微球.采用透射电子显微镜(TEM)、X射线衍射仪(XRD)和氮气吸附实验等对Au@SiO_2中空微球进行表征.通过设计对比实验,证实阿拉伯树胶在中空结构形成过程中起到模板剂的作用.催化性能测试结果表明,所制备的Au@SiO_2中空微球在硼氢化钠还原亚甲基蓝的反应中表现出良好的催化活性和重复使用性.     

Rheological properties of water-soluble cross-linked xanthan gum

Water-soluble crossslinked xanthan gum (CXG) was prepared from xanthan gum (XG) and epichlorohydrin under alkaline condition by ethanol solvent method. Rheological properties and heat resistance performance of different concentrations of aqueous XG and CXG solutions were investigated. The results showed that the apparent viscosity of 4 g · L^?1 CXG solution was 2.57 times that of 4 g · L^?1 XG solution. The storage modulus G′ and the loss modulus G″ of CXG solutions were greater than those of XG solutions, and viscoelastic and thixotropic properties were more significant in CXG solutions. At 80°C, these two solutions were sheared at 170 s^?1 for 90 minutes, the reserved viscosity was 32.30 and 62.15 mPa · s for XG and CXG solutions, respectively. The heat resistance performance of CXG solution was better than that of XG solution. Nonlinear co-rotational Jeffreys model could be applied to describe the flow curves of XG and CXG solutions correctly, and the calculated values were in good agreement with the experimental data.     

An Injectable System for Local and Sustained Release of Antimicrobial Agents in the Periodontal Pocket

Periodontitis treatments usually require local administration of antimicrobial drugs with the aim to reduce the bacterial load inside the periodontal pocket. Effective pharmaceutical treatments may require sustained local drug release for several days in the site of interest. Currently available solutions are still not able to fulfill the clinical need for high‐quality treatments, mainly in terms of release profiles and patients' comfort. This work aims to fill this gap through the development of an in situ gelling system, capable to achieve controlled and sustained release of antimicrobial agents for medium‐to‐long‐term treatments. The system is composed of micrometer‐sized β‐cyclodextrin‐based hydrogel (bCD‐Jef‐MPs), featured by a strong hydrophilic character, suspended in a synthetic block‐co‐polymer solution (Poloxamer 407), which is capable to undergo rapid thermally induced sol–gel phase transition at body temperature. The chemical structure of bCD‐Jef‐MPs was confirmed by cross‐correlating data from Fourier transform infrared (FTIR) spectroscopy, swelling test, and degradation kinetics. The thermally induced sol–gel phase transition is demonstrated by rheometric tests. The effectiveness of the described system to achieve sustained release of antimicrobial agents is demonstrated in vitro, using chlorhexidine digluconate as a drug model. The results achieved in this work disclose the potential of the mentioned system in effectively treating periodontitis lesions.

     

葡萄糖接枝瓜尔胶的合成及表征

本文在研究1,6-脱水葡萄糖均聚的基础上,提出了一种用1,6-脱水葡萄糖对瓜尔胶进行绿色化改性的新方法,并通过核磁对瓜尔胶的葡萄糖接枝产物进行表征,发现随着1,6-脱水葡萄糖与瓜尔胶质量比的增加,产物的葡萄糖摩尔取代度逐渐增大,当1,6-脱水葡萄糖与瓜尔胶质量比为3:1时,共聚产物的摩尔取代度可达0.6.1,6-脱水葡...     

Synthesis and characterization of phenolic‐type beads by dispersion polymerization of 2‐phenoxyethanol with formaldehyde using gum acacia powder as stabilizer

In this study, we report the preparation of phenolic beads (PB) via a novel dispersion polymerization of 2‐phenoxyethanol (PE) and formaldehyde, in which gum acacia powder (GAP), formic acid, and sulfuric acid are employed as the steric stabilizer, the reaction medium and the catalyst, respectively. The effects of a variety of reaction parameters, including the stabilizer concentration, the agitation rate, the polymerization temperature, the molar ratio of formaldehyde to 2‐phenoxyethanol (F/P) and the amount of sulfuric acid, on the particle size and size distribution (PDI) as well as particle morphology have been investigated. Particularly, phenolic beads of a size 565 µm as well as a narrow particle size distribution (PDI = 1.153) have been prepared under the following conditions: the stabilizer concentration 2.5%, the agitation rate 700 rpm, the polymerization temperature 60°C, the molar F/P ratio 3:1, and the amount of catalyst 8 ml. In addition, a mechanism for the particle formation in dispersion polymerization of PE and formaldehyde has also been proposed. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of surfactant on porosity and swelling behaviors of guar gum-g-poly(sodium acrylate-co-styrene)/attapulgite superabsorbent hydrogels

Novel fast-swelling porous guar gum-g-poly(sodium acrylate-co-styrene)/attapulgite (GG-g-P(NaA-co-St)/APT) superabsorbent hydrogels were prepared by simultaneous free-radical graft copolymerization reaction of guar gum (GG), partially neutralized AA (NaA), styrene (St) and attapulgite (APT) using N,N'-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution and the surfactant self-assembling templating pore-forming technique. Fourier transform infrared (FTIR) spectroscopy confirmed that the surfactant could be removed from the final hydrogel product by methanol/water (8:1, v/v) washing process and the surfactant only act as micelle template to form pores. The effect of surfactant type on the porous microstructure of the hydrogel was assessed by field emission scanning electron microscope (FESEM). It was shown that incorporation of proper amount of anionic surfactant sodium n-dodecyl sulfate (SDS) in the gelling process of the hydrogel can obviously enhance the swelling capacity and initial swelling rate. The salt-sensitivity of the SDS-added hydrogel in distilled water and 15 mmol/L NaCl, CaCl(2) solution or 15 mmol/L NaCl and CaCl(2) solution was investigated, and it was found that the swelling-deswelling capability is quite reversible. A similar reproducible on-off switching behavior was observed in the 1 mmol/L solution of phosphate buffer at pH 2.1 and 7.4.     

新疆油田玛湖地层水配制有机硼胍胶压裂液的应用研究

新疆油田玛湖区块地层水矿化度高且含高价金属离子,对使用该区块地层水配制有机硼胍胶压裂液的性能造成了不利影响。针对玛湖地区地层水配制有机硼胍胶压裂液时,溶胀时间久、交联冻胶热稳定性差的问题,本文借助化学屏蔽技术,根据屏蔽剂工作原理,结合水中金属离子含量,推导出了屏蔽剂合理加量的计算公式,通过热稳定性能测试,确定出了适用于玛湖地层水配制有机硼胍胶压裂液的屏蔽剂AH-1,在此基础,对玛湖地层水配制的有机硼胍胶压裂液性能进行了评价,结果表明：屏蔽剂AH-1的加入可使玛湖地层水配制的压裂液的剪切黏度维持在220mPa?s左右,且其溶胀性能、破胶性能均满足行业标准,现场试验取得了良好的应用效果,为玛湖油田的开发提供了资源保障。     

Encapsulation and survival of a chondrocyte cell line within xanthan gum derivative

A chemical derivative of xanthan gum polysaccharide is investigated as a new artificial matrix for the encapsulation of chondrocytic cells. Toward this goal, a novel micro-droplet generator is developed to produce microcapsules. Microcapsules with an average diameter of 500 μm, smooth surface, and homogeneous size distribution are obtained. ATDC5 cells encapsulated in carboxymethyl xanthan (CMX) microcapsules remain viable and are observed to proliferate for prolonged culture periods with enhanced metabolic activity. Furthermore, retention of the chondrogenic phenotype is exhibited by the cells within CMX, suggesting the ability of this material to be applied in cell-delivery therapies.     

基于超声波辅助法的杜仲籽蛋白提取工艺优化

采用单因素和正交试验方法对超声波辅助提取杜仲籽蛋白工艺进行了优化.先选取料液比、超声时间、超声温度、浸提pH值等条件对杜仲籽蛋白的提取工艺进行单因素实验,采用L9(34)正交试验确定本工艺最佳条件.实验结果表明,在超声波辅助提取杜仲籽蛋白最佳工艺条件（料液比为1∶25,超声时间为30 min,超声温度为50 ℃,浸提pH值为10.0）下,杜仲籽蛋白提取率为77.03%.     

甘蔗糖蜜发酵产黄原胶优良菌株的选育

黄原胶是由野油菜黄单胞菌发酵生产的重要的商业微生物多糖产品,实验通过微波诱变处理保藏菌株,筛选到一株能以甘蔗糖蜜为碳源发酵生产黄原胶的优良正突变株X12,实验结果表明：在初步确定的实验条件下,该菌株发酵生产黄原胶的产量达22.14 g/L,是未诱变菌株20183的1.53倍,传代实验表明,突变菌株X12的黄原胶产量及性状无大变化,遗传性状稳定。