Experimental and predicted excess molar enthalpies of some working pairs for absorption cycles

In this work, the measured excess molar enthalpies of absorption heat pump working pairs (refrigerant + absorbent), viz. water + mono-, di- and tri-ethylene glycol, water + glycerol, and ethanol + di- and tri-ethylene glycol mixtures are presented at 298.15 K and ambient pressure using a Setaram Calvet C80 calorimeter. The experimental results are represented and correlated by a Redlich–Kister type equation. Modeling of the excess enthalpies has been performed using the UNIFAC molecular group-contribution method, and UNIQUAC Gibbs energy model. In addition, the data and results are used to predict the Gibbs energy of all binary systems. This allows a preliminary evaluation of the suitability of the binary systems as heat pump working pairs.     

甘油对酪蛋白酸钠光谱性质的影响

酪蛋白酸钠(sodium caseinate, SC)所制的可食食品包装膜能有效延缓食品中水份的迁移和扩散以及阻止氧气的氧化等从而对食品起到很好地保鲜和保护作用, 由于酪蛋白亲水性较强, 使其所制膜阻水性和机械性能均较差, 甘油(glycerol, G)作为添加剂可以增强酪蛋白酸钠膜的韧性和阻水性, 为进一步阐明G和SC之间的作用方式及对酪蛋白酸钠结构产生的影响, 本实验利用荧光光谱、傅里叶红外光谱和紫外光谱特性对它们的作用方式进行了研究。结果表明: G的加入可以使SC的荧光强度降低, 由荧光强度变化速率和甘油的浓度的双对数回归曲线得出了G和SC的结合常数为1.127×103 L·mol-1和结合位点数为1.161, 得出G和SC分子之间结合方式为弱化学键;虽然添加G前后SC的红外光谱的吸收峰几乎相同, 但吸收强度存在较大差异, 说明SC二级结构受到了影响, 使得β折叠β-转角结构减少, α螺旋、无规则卷曲、结构显著增多, 以及分子间氢键加强;分析紫外光谱得出, G的加入没有改变SC肽键的结构, 而是与SC以非共价键的方式结合形成分子质量更大的聚合物并使吸收峰值强度下降。该研究从分子的角度揭示了G和SC分子间的作用方式。     

SECM Studies on the Electrocatalytic Oxidation of Glycerol at Copper Electrodes in Alkaline Medium

This study aims at analyzing the reaction mechanism of the electrooxidation of glycerol at copper surfaces in NaOH solutions using Scanning Electrochemical Microscopy (SECM) in the substrate generation/tip collection (SG/TC) mode. Experiments showed the dependence of the current at the tip on the distance between generator and tip, as well as on the concentration of the NaOH solution. The current at the tip decreased significantly after addition of glycerol, as a result of the competition between diffusion of the free‐soluble Cu(III) species and its consumption during the diffusion in the solution. The determination of the analyte in a castor biodiesel sample employing a single copper microelectrode was carried out.     

Multiporous Carbon Encapsulated Ni Nanoparticles Promoting Glycerol Valorisation towards Hydrogenation against Rearrangement†

A dual‐templating method was used to synthesize a series of hierarchical carbon supports containing different proportions of spherical macropores (ca. 200 nm in diameter) and mesoporous channels (ca. 4 nm in diameter). These and some other conventional carbon materials were subsequently impregnated with Ni and tested for the conversion of glycerol. The hierarchical catalysts exhibited a significantly higher conversion (96%) and selectivity (77%) to 1,2‐propanediol, and the specificity selectivity coefficient (6.1) towards 1,2‐propanediol against lactic acid was three times higher than that observed over a conventional Ni/C_micro catalyst (2.1). The enhanced performance of these materials, compared with the Ni nanoparticles supported on conventional carbon supports, was attributed to their high surface areas (> 1110 m²?g^?1) and large pore volumes (ca. 0.4 cm³?g^?1) permitting greater accessibility of substrate and/or intermediates to Ni active sites. Given that the concentration of accessible Ni sites in these materials is higher, a competitive benzilic‐acid‐rearrangement reaction to produce lactic acid was suppressed, leading to an enhanced hydrogenation selectivity to 1,2‐propanediol. This study evidences the potential benefits, which can be established from utilizing hierarchical support materials in the valorization of biomass.     

Preparation of a novel biodegradable film by co-fermentation of straw and shrimp shell with Aureobasidium pullulans and Photobacterium sp. LYM-1

The green and high-value recycling of shrimp shell and straw remains a worldwide problem. This study aimed to investigate the potential utilization of a fermentation broth (FB) which contains shrimp shell and straw as a new source for preparation of biodegradable films. Aureobasidium pullulans and Photobacterium sp. LYM-1 were used in the fermentation. The cellulase activity was 115.92 U/mL and chitinase activity was 17.89 U/mL in FB. The polysaccharides concentration in FB was 1.05 mg/mL after 7 days of fermentation. An eco-friendly PVA-reinforced FB biodegradable film (FBBF) was successfully prepared and the effect of different plasticizers and surfactants on the mechanical, structural, and impermeability properties of the film was determined. The formation of new bonds between PVA and FB was proved by FTIR spectroscopy. The FBBF containing 0.25 % (w/v) glycerol and 0.01 % (v/v) tween-20 showed better strength properties. Elongation and water-swelling properties were highly improved by adding 0.2 % (m/v) citric acid. According to FE-SEM images, the smooth and tight surface of citric acid added FBBF was observed. Interestingly, the FBBF film showed good heat/moisture capacity, antifungal, and degradation properties. This report reveals a new green, and high-value recycling of straw and shrimp shell by the co-fermentation with A. pullulans and Photobacterium sp. LYM-1. It is also a novel way for the preparation of biodegradable film.     

液滴在超疏水植物叶面的沉积：实验和分子动力学模拟

农药液滴在靶标植物叶面的动态沉积对于提高农药利用率具有重要的意义,特别是在超疏水植物叶面的动态沉积。在本文中,我们利用生物基表面活性剂和甘油之间的氢键作用来增强液滴在超疏水植物叶面的有效沉积。在较低浓度的山梨醇-烷基胺表面活性剂溶液中,添加0.001%的甘油,可有效抑制液滴在不同超疏水/疏水植物叶片表面的弹跳和飞溅行为。结果表明,甘油的加入并没有显著改变山梨醇-烷基胺表面活性剂溶液的表面张力、粘度和聚集体的形态。核磁共振波谱(DOSY)显示,甘油加速了山梨醇-烷基胺表面活性剂分子的扩散速度。利用分子动力学模拟,对山梨醇-烷基胺表面活性剂/甘油体系的能量演化及表面活性剂相对于固体表面距离的分布进行了研究。这项目工作不仅为抑制液滴在植物叶面的弹跳飞溅提供了一种建设性的方法,而且为选择农用表面活性剂提供了理论基础。     

丙烯醇反马氏水合制备1,3-丙二醇

1,3-丙二醇具有很高的经济价值,是合成纤维聚对苯二甲酸丙二酯的重要原料。基于甘油甲酸介入法获得的丙烯醇作为平台分子,通过丙烯醇与TiCl4-NaBH4反应,首次实现常温常压下1,3-丙二醇的制备, 为1,3-丙二醇的合成提供了一条新的路径。在最优条件下,1,3-丙二醇的产率68.73%,推测反应机理为：TiCl4和NaBH4发生反应,生成中间体 “BH3”,进而实现了丙烯醇反马氏水合制备1,3-丙二醇。     

甘油骨架上含芳硒基的替加氟硫代磷脂缀合物的合成及生物活性

以O-(2-邻苯二甲酰亚氨基)乙基-1,3,2-二氧磷杂环戊烷硫代磷酸酯1及2-邻苯二甲酰亚氨基乙醇环甘油硫代磷脂缀合物2为模型,研究开环反应的条件.结果表明,在室温下,甲醇对化合物1中1,3,2-二氧磷杂环戊烷中的磷原子的亲核进攻,生成O-甲基-O-羟乙基-O-(2-邻苯二甲酰亚氨基)乙基硫代磷酸酯3,但是在此条件下,甲醇与化合物2不反应.在室温下,以异丙醇作溶剂,苯硒酚与化合物2不反应.在氢氧化钾存在下,以异丙醇/水作溶剂(体积比20:1),在室温下,硒酚可以有效地进攻中化合物2中1,3,2-二氧磷杂环戊烷中的碳原子生成相应的开环产物.按照这一反应条件,顺利实现了硒酚对N¹-(2-呋喃基)-N³-羟烷基-5-氟脲嘧啶硫代环甘油磷脂缀合物的亲核开环,生成甘油骨架的端碳原子上带有芳硒基新颖的磷脂核苷缀合物.对开环反应的机理进行了探讨.体外细胞毒性试验结果表明:产物对膀胱癌细胞T-24、胃癌细胞BGC-823的恶性增殖抑制效果优于替加氟;但对正常肝上皮细胞毒性也大于替加氟.     

光学活性C3合成子的不对称合成及应用

叙述了光学活性甘油醇及其衍生物等手性Ｃ３合成的合成方法,以及这些手性化合物在不对称有机合成中的应用,参考文献２４篇。     

铯钨青铜的合成及其对甘油脱水制丙烯醛的催化性能

以仲钨酸铵、硝酸铯为原料,乙二胺四乙酸(EDTA)为模板剂和还原剂,采用水热法合成了铯钨青铜,考察了EDTA用量、水热前驱液浓度、铯钨比等条件对水热产物组成及形貌的影响,并以所得产物为催化剂在固定床反应器中进行甘油脱水制丙烯醛的反应研究,发现铯含量对催化性能有较大影响,在Cs/W摩尔比为0. 2∶1时催化性能最好,甘油转化率达到81. 3%,丙烯醛的选择性达到92. 9%。