“拟双子”阴离子表面活性剂在癸烷/水界面的分子动力学模拟

采用全原子分子动力学模拟方法研究了壬基酚取代的系列烷基磺酸盐表面活性剂在癸烷/水界面的微观聚集行为,通过分析界面厚度、界面生成能和界面张力以及表面活性剂分子与水分子之间的径向分布函数和配位数,讨论了不同磺烷基链长度对壬基酚基取代烷基磺酸盐表面活性剂界面性质的影响.结果表明,磺烷基链长为12时,表面活性剂的界面张力最低,界面厚度和界面生成能最大.     

Preparation and antimicrobial properties of LL‐37 peptide immobilized lignin/caprolactone polymer film

The use of biopolymers has gained priority in tissue engineering and biotechnology, both as dressing material and for enhancing treatment efficiency. There is a demand for new biopolymers designed with protease inhibitors and antimicrobials. LL‐37 is an important antimicrobial peptide in human skin and exhibits a broad spectrum of antimicrobial activity against bacteria, fungi, and viral pathogens. Using lignin which is an abundant carbohydrate polymer in nature and a polyacrylic acid, we prepared a lignin/caprolactone biodegradable film by plastifying caprolactone and polyacyrlic acid. Lignin/caprolactone biodegradable film was activated with CDI and then immobilized LL‐37 peptide. The structure was elucidated in terms of its functional groups by attenuated total reflectance‐fourier transform infrared spectroscopy (ATR‐FTIR), and the morphology of the lignin/caprolactone biodegradable film was characterized by scanning electron microscopy (SEM) before and after the immobilization process. The amount of LL‐37 immobilized was determined by ELISA method. It was found that 97% of LL‐37 peptide was successfully immobilized onto the lignin/caprolactone biodegradable film. Antimicrobial activity was determined in the lignin/caprolactone biodegradable film samples by quantitative antimicrobial activity method. According to the results, LL‐37 immobilized lignin/caprolactone biodegradable film samples were effective on test organisms; Gram‐positive Staphylococcus aureus and Gram‐negative Escherichia coli. In bio‐compatibility assays, the ability to support tissue cell integration was detected by using 3 T3 mouse fibroblasts. Samples were examined under transverse microscope, non‐immobilized sample showed a huge cellular death, whereas LL‐37 immobilized lignin/caprolactone biodegradable film had identical cellular growth with the control group. This dual functional lignin/caprolactone biodegradable film with enhanced antibacterial properties and increased tissue cell compatibility may be used to design new materials for various types of biological applications.     

Improving the Yield and Rate of Acid-Catalyzed Deconstruction of Lignin by Mechanochemical Activation

Lignin is a potential biomass feedstock from plant material, but it is particularly difficult to economically process. Inspired by recent ball-milling results, state-of-the-art quantum mechanochemistry calculations have been performed to isolate and probe the purely mechanochemical stretching effect alone upon acid-catalyzed deconstruction of lignin. Effects upon cleavage of several exemplary simple ethers are examined first, and with low stretching force they all are predicted to cleave substantially faster, allowing for use of milder acids and lower temperatures. Effects upon an experimentally known lignin fragment model (containing the ubiquitous β-O-4 linkage) are next examined; this first required a mechanism refinement (3-step indirect cleavage, 1-step side reaction) and identification of the rate-limiting step under zero-force (thermal) conditions. Mechanochemical activation using very low stretching forces improves at first only yield, by fully shutting off the ring-closure side reaction. At only somewhat larger forces, in stark contrast, a switch in mechanism is found to occur, from 3-step indirect cleavage to the direct cleavage mechanism of simple ethers, finally strongly enhancing the cleavage rate of lignin. It is concluded that mechanochemical activation of the common β-O-4 link in lignin would improve the rate of its acidolysis via a mechanism switch past a low force threshold. Relevance to ball-milling experiments is discussed.     

十二烷基苯磺酸钠增敏乙基紫共振光散射法测定人尿中痕量1-羟基芘

基于乙基紫(EV)与1-羟基芘(1-OHP)反应形成离子缔合物,导致体系的共振光散射(RLS)增强,建立了测定1-OHP的共振光散射法.在pH 8.0Tris-HCl缓冲介质中,最大RLS峰位于396 nm,其强度与1-OHP浓度成线性关系.加入表面活性剂十二烷基苯磺酸钠(SDBS),体系的灵敏度可提高两倍以上.方法的线性范围为4.0～982 μg·L-1,相关系数r=0.999 4,检出限1.2 μg·L-1,相对标准偏差为5.8%～7.9%,平均回收率为94%(n=6).已成功用于人尿中痕量1-OHP的测定,结果满意.     

二氧化氯氧化云杉木质素的光谱研究

采用傅里叶变换红外光谱(FTIR)、紫外-可见光谱(UV-visible)、傅里叶变换拉曼光谱(FT-Raman)以及核磁共振(1H NMR)分析技术对云杉木质素被二氧化氯氧化前后的结构变化进行了研究。当木质素被二氧化氯氧化时,其骨架结构中的芳香环基团被有效地氧化开环。红外光谱显示木质素中的愈疮木基特征峰强度显著降低,紫丁香基苯基以及对羟基苯基特征吸收峰完全消失,在被氧化后的木质素中出现CO 共轭羰基伸缩振动特征峰。紫外光谱显示木质素在被氧化后位于280 nm处的紫外吸收显著降低。1H核磁共振波谱显示,木质素中连接在芳香环侧链的甲氧基数量被氧化后出现显著的降低,同时与苯环相连的脂肪族侧链在后也相应地减少。研究结果说明二氧化氯能有效地氧化木质素中的芳香环,并将其氧化为带有CO基因的粘康酸及其酯类物质或带有醌型基团的物质。     

碱木素的近红外光谱吸收机理的研究

通过碱木素模型物对醌、邻醌和香兰素的溶液在800～900 nm的近红外光谱波段内的吸收谱图的对比发现,对醌和邻醌在此波段产生较强的吸收,而香兰素基本上没有吸收,证明了碱木素的醌型结构在800～900 nm波段内产生特征吸收。对银杏和夹竹桃磨木木素碱处理前后的溶液在800～900 nm波段内的吸光度的差别分析,发现夹竹桃的磨木木素的吸光度的相对变化更大,这是由于夹竹桃磨木木素经碱处理后产生了更多的醌型结构。这也是在硫酸盐法蒸煮过程中在800～900 nm波段内阔叶材的蒸煮液吸光度大于针叶材的蒸煮液吸光度的主要原因。     

模板法合成含镧的层状无机-有机纳米复合材料

以表面活性剂十二烷基磺酸钠为模板制备了含稀土元素La的无机-有机纳米复合材料。通过XRD、SEM、HRTEM、EDX等的表征，证明所得的稀土复合物为层状结构，且十二烷基磺酸钠与La的比例为1∶1。考察了反应温度、反应时间以及原料配比等对复合物结构的影响。     

羟基取代烷基苯磺酸盐界面扩张粘弹性质

研究了2-羟基-3,5-二癸基苯磺酸钠(C10C10OHphSO3Na)表面和正癸烷-水界面上的扩张粘弹性质, 考察了平衡时间对界面性质的影响. 研究结果表明, 羟基取代烷基苯磺酸钠具有十分特异的界面性质, 其扩张模量比一般表面活性剂大一个数量级, 达到平衡的时间较长, 形成的界面膜弹性较大. 界面张力弛豫测定结果表明, 平衡时界面上存在特征时间长达103 s的慢过程. 上述实验结果可能是由于羟基间形成氢键造成的.     

不抑制电导检测的反相高效液相色谱法分析烷基磺酸盐

本工作采用反相高效液相色谱法分析表面活性剂驱油研究中所用C_(10)～C_(16)烷基磷酸盐。用含有低浓度磷酸二氢钠的移动相和电导检测器,不需抑制柱,直接测检洗脱的烷基磺酸盐,方法简单、快速、灵敏。     

铋(Ⅲ)-8-羟基喹哪啶体系极谱行为——表面活性剂增敏机理和分析应用——Ⅱ.铋(Ⅲ)-8-羟基喹哪啶络合物电极反应和十二烷基苯磺酸钠增敏机理

试验表明,铋(Ⅲ)-8-羟基喹哪啶(8-OXQ)络合物(pHll,-0.60V)的峰电流(p)具吸附特性,为准可逆电极反应过程,其电子转移数(n),传递系数(α)及饱和吸附量(Γ_ο)分别为3,0.45,6.5×10~(-12) mol/cm~2。加入十二烷基苯磺酸钠(SDBS)未形成三元络合物,因SDBS的超载强烈吸附,引起诱导吸附,电双层结构激烈变化,而使电流峰形巨变,电流峰高(i_p)增大10余倍。讨论并指出SDBS对Bi(Ⅲ)与8-羟基喹啉(8-OX)及衍生物络合吸附电流增敏或抑制,与试剂组分、结构、解离态及络合物存在状态、电荷数、符号有关。