脂溶性儿茶素类化合物的制备研究进展

儿茶素类化合物是一类具有多种生理活性的多酚类抗氧化剂,本文综述了国内外利用分子修饰法制备脂溶性儿茶素类化合物的进展。化学法主要利用酰氯在化学催化剂作用下反应制备脂溶性儿茶素,但是酰化反应发生的位点有所不同,总的来说酰基供体碳链长度一般大于等于8;酶法主要利用脂肪酶使脂肪酸或脂肪酸酯通过直接酯化或酯交换反应制备脂溶性儿茶素,在儿茶素及其化合物上键合烷基,由此提高了儿茶素类化合物在油脂体系中的溶解度,拓展了其应用领域。     

有机氟改性丙烯酸酯树脂研究新进展

综述了有机氟改性丙烯酸酯树脂的化学改性制备方法(如常规乳液聚合、核壳乳液聚合和无皂乳液聚合等)及其研究新进展,总结了有机氟改性丙烯酸酯树脂在外墙涂料、防腐防污涂料等领域的应用现状,并展望了该研究领域的发展前景。     

Approach to disrupting thick intermetallic compound interfacial layer in friction stir brazing (FSB) of Al/Cu plates

Friction stir brazing (FSB) was developed for dissimilar joining to overcome the problems associated with friction stir lap welding (e.g. pin wear, narrow bonded area, hook defect) by metallurgical reaction instead of plastic flow. To enhance the thermomechanical effect of the rotating shoulder, a pin free tool with a large shoulder of 30 mm diameter was used in FSB of 5 mm thick Al/Cu plates in stepped lap configuration with Zn braze. Compared to the case using common tool of 20 mm diameter, it was found that although the intermetallic compound (IMC) layer grew thickly, it was disrupted into particles, and end crack within thick IMC layer was eliminated. As a result, the joint fractured not along interface and the fracture load increased by as much as 2271 N. This work proposed an approach to disrupting continuous IMC into particles by enhancing the mechanical effect of rotating shoulder.     

Effect of surface-mannose modification on aerosolized liposomal delivery to alveolar macrophages

Purpose: The effect of surface-mannose modification on aerosolized liposomal delivery to alveolar macrophages (AMs) was evaluated in vitro and in vivo. Method: 4-Aminophenyl-α-D-mannopyranoside (Man) was used for surface-mannose modification, and mannosylated liposomes with various mannosylation rates (particle size: 1000 nm) were prepared. Results: In the in vitro uptake experiments, the uptake of mannosylated liposomes by AMs was increased with the increase in the mannosylation rate over the range 2.4–9.1 mol% Man and became constant at over 9.1%. Thus, the most efficient mannosylation rate was 9.1 mol% Man. Furthermore, free mannose inhibited the uptake of mannosylated liposomes by AMs. This indicates that the uptake mechanism of mannosylated liposomes by AMs is mannose receptor-mediated endocytosis. In the in vivo animal experiments, the mannosylated liposomes (mannosylation rate, 9.1 mol% Man) were more efficiently delivered to AMs after pulmonary aerosolization to rats than nonmodified liposomes and did not harm lung tissues. Conclusion: These results indicate that surface-mannose modification is useful for efficient aerosolized liposomal delivery to AMs.     

Physicochemical properties of pine-derived bio-chars modified by metal oxides and their performance in the removal of NO

Pine-derived bio-chars have been prepared at different temperatures with and without KOH chemical activation. Three metal oxides (V₂O₅, MnO and CuO) were loaded on this chars by incipient-wetness impregnation method respectively. Pine wood pellets were characterized by thermogravimetric, and pine-chars samples were characterized by SEM-EDS, XRD, N₂ physisorption and FTIR. Activity test for the selective catalytic reduction of NO with NH₃ was also carried out in dry simulated flue gas at fixed temperature 160 °C. The results show that pretreatment with KOH and carbonization at 600 °C seems to be the best method for pine-chars preparation. Active metal oxides are well distributed on the surface of carbon support and are partly reduced by carbon during preparation. The mesopores disappear in V- and Mn-containing samples, and V-addition could decrease the amount of micropores as well. At the fixed temperature 160 °C, the active metal oxides have an order of CuO > V₂O₅ >> MnO_x >> Non-modified sample on the NO reduction activity. Pine-chars modified by CuO seems to be the best option in this research.     

Synthesis of new green-emitting KBa1−xScSi3O9:Eu2+x phosphors for white LEDs

New green-emitting KBa_1−xScSi₃O₉:Eu²⁺_x phosphors for white LEDs were synthesized by a conventional solid-state reaction method. The obtained KBa_1−xScSi₃O₉:Eu²⁺_x phosphors show the strong broad optical absorption band from UV to blue light region and exhibit broad green emission with a peak at 521 nm under excitation at 405 nm due to the allowed 4f⁶5d¹−4f⁷ transition of Eu²⁺. Optimization of Eu²⁺ concentration resulted in the highest green emission peak intensity was obtained at the composition of KBa_0.94ScSi₃O₉:Eu²⁺_0.06, and the relative emission intensity of this phosphor was 32% of that of a commercial YAG:Ce³⁺ phosphor.     

Improving the reliability of metallic structures in service in the conditions with low climatic temperatures by efficient application of advanced methods of modification of the zone of the welded joint

The concept of investigations carried out to increase the reliability of metallic structures designed for operation in the conditions of low climatic temperatures is described. The worldwide tendencies in the investigation of the processes of the formation and fracture of materials and components at low climatic temperatures are analysed. The main methodological approaches, directed at ensuring high parameters of the service reliability of structures in low carbon, low alloy steels are outlined. The experimental data obtained in this area are analysed. The directions for further experimental and theoretical studies are indicated.     

3种脂溶性酚类对紫苏籽油的抗氧化作用研究

采用Schaal烘箱法,以过氧化值和α-亚麻酸含量为指标,比较了3种脂溶性酚类及人工合成抗氧化剂对紫苏籽油的抗氧化效果。结果表明,当抗氧化剂添加量为100 mg/kg时,基于过氧化值的抗氧化效果为香芹酚百里香酚、丁香酚BHT、BHA。低添加量抗氧化剂(1~100 mg/kg)紫苏籽油中α-亚麻酸含量均高于不添加抗氧化剂的处理组。香芹酚的最适添加量为5 mg/kg,α-亚麻酸含量为6.399 mg/g,与4℃保存的紫苏籽油含量相近;BHT的最适添加量为50 mg/kg,α-亚麻酸含量为6.987 mg/g,高于4℃保存的紫苏籽油;分别添加100 mg/kg的香芹酚与100 mg/kg的BHT的紫苏籽油中α-亚麻酸含量相近,说明二者抗氧化能力相当。研究结果证实了香芹酚、百里香酚、丁香酚对紫苏籽油具有较好的抗氧化作用,为安全高效的天然酚类抗氧化剂的筛选及其在油脂食品中的应用提供理论参考。