含能五唑离子盐的能量性能预估

为了在同一水平上比较含能五唑离子盐的密度、生成热、爆速和爆压,采用密度泛函理论,对近两年合成的五大类16个非金属N_5~ˉ离子盐进行了研究。结果表明在MP2/6-311++G(d,p)理论水平上,根据Born-Haber能量循环计算的五唑离子盐的生成热为95.2～1362.0 k J·mol~(-1),三唑类N_5~ˉ离子盐的平均生成热最高。这些五唑离子盐的密度为1.395～1.650 g·cm~(-3)(298.15 K),远远低于理论预测的全氮化合物的密度。通过Kamlet-Jacobs公式计算的爆速和爆压结果与EXPLO5的计算结果吻合良好,大部分五唑含能离子盐的爆速为6500～8000 m·s~(-1);爆压为15～26 GPa,低于RDX的爆速和爆压。N_5~ˉ的缩二胍盐、羟胺盐和肼盐的理论爆轰性能突出,它们的爆速(8622～9032 m·s~(-1))与RDX持平或者略高,爆压(29.5～32.3 GPa)均低于RDX,并未展现出全氮阴离子衍生物的明显优势,也远未达到对它们超高能量的预期。     

废涂布纸回用过程中胶黏物的分析和控制

以真空镀铝原纸为原料制备废涂布纸浆,通过SEM、红外光谱、电荷需求量等表征手段,研究了大胶黏物、微胶黏物和DCS(溶解和胶体物质)的来源、形态、成分、阴离子垃圾贡献率。结果表明,丁苯胶乳是胶黏物的主要来源,大胶黏物包覆颜料形成大胶黏物混合物,碳酸钙对微胶黏物吸附沉积,而DCS稳定分散于白水中,具有最大的阴离子垃圾贡献率。大胶黏物可通过纸张抄造脱离白水,而微胶黏物和DCS可通过添加0.2%用量的阳离子聚乙烯亚胺进行控制,具有较好的效果。     

猪血多肽亚铁螯合盐的体外抗氧化作用研究

研究了猪血多肽亚铁螯合盐对超氧阴离子自由基（O2-·）和过氧化氢（H2O2）的清除作用,并比较了维生素C、猪血多肽亚铁和猪血多肽对二者的清除能力。实验结果表明:猪血多肽亚铁螯合盐能清除超氧阴离子自由基（O2-·）和过氧化氢（H2O2）,维生素C、猪血多肽亚铁和猪血多肽这三种物质对超氧阴离子自由基（O2-·）和过氧化氢（H2O2）清除能力的强弱顺序为维生素C>猪血多肽亚铁>猪血多肽,故猪血多肽亚铁螯合盐具有较强的清除超氧阴离子自由基（O2-·）和过氧化氢（H2O2）的能力。      

叶酸的提取及抗氧化性研究

研究果蔬中叶酸的最佳提取条件及叶酸的抗氧化活性.以油菜,香菇,香蕉为原料,以提取温度、提取剂的浓度、提取时间为因素进行正交试验,确定最佳提取条件,用荧光光度法测定叶酸含量.采用Fenton体系、邻苯三酚自氧化体系,分别研究不同浓度的叶酸对羟自由基( ·OH)和超氧自由基(O2-·)的清除效果.结果表明果蔬中叶酸的最佳提...     

Studies on antioxidant activities of mucuna seed (Mucuna pruriens var utilis) extract and various non‐protein amino/imino acids through in vitro models

The antioxidant activities of a methanolic extract of mucuna beans (Mucuna pruriens var utilis) and several non‐protein amino/imino acids, namely L ‐3,4‐dihydroxyphenylalanine (L ‐dopa), L ‐3‐carboxy‐6,7‐dihydroxy‐1,2,3,4‐tetrahydroisoquinoline (compound I), (?)‐1‐methyl‐3‐carboxy‐6,7‐dihydroxy‐1,2,3,4‐tetrahydroisoquinoline (compound II) and 5‐hydroxytryptophan (5‐HTP), were evaluated. By virtue of their hydrogen‐donating ability, all the tested compounds and the mucuna seed extract showed excellent reducing power, with the highest values being recorded for L ‐dopa in a dose‐dependent manner. Similarly, as compared with synthetic antioxidants (BHT and BHA) and quercetin, all the tested compounds and the seed extract were found to be more potent in free radical‐scavenging activity (P < 0.05) against α,α‐diphenyl‐β‐picrylhydrazyl (DPPH^?) radicals. Hydroxyl radicals (OH^?) and superoxide anion radicals (O₂^??) were effectively scavenged by the tested compounds, with the exception that no scavenging activity of 5‐HTP was observed on (O₂^??) up to a concentration of 2 mg ml^?1, as was also the case for BHA. Among the tested non‐protein amino/imino acids and seed extract the highest peroxidation‐inhibiting activity (95%) was recorded for 5‐HTP. On the other hand, in the linoleic acid/β‐carotene‐bleaching system, L ‐dopa, compound I and compound II acted as pro‐oxidants, whereas the seed extract showed only weak antioxidant activity as in the linoleic acid emulsion system. Copyright © 2003 Society of Chemical Industry     

Preparation of eicosapentaenoic acid concentrates from sardine oil by Bacillus circulans lipase

An extracellular lipase derived from Bacillus circulans, isolated from marine macroalga, Turbinaraia conoides, was used to prepare n-3 polyunsaturated fatty acid (PUFA) concentrates from sardine oil triglycerides. The enzyme was purified 132-fold with specific activity of 386 LU/mg. The purified lipase was able to enrich sardine oil with 37.7 ± 1.98% 20:5n-3 and 5.11 ± 0.14% 18:3n-3 in the triglyceride fraction after 3 h of hydrolysis. Lower hydrophobic constants of n-3 fatty acids (18:3n-3_logP = 5.65; 20:5n-3_logP = 5.85, respectively) than n-6 (20:4n-6_logP = 6.16) resulted in higher hydrolytic resistance of the former toward lipase, leading to their enrichment in the triglyceride fraction. Lipase-catalysed hydrolysis of sardine oil for 3 h, followed by urea complexation, provided free fatty acids containing 51.3 ± 4.65% 20:5n-3. The purified methyl ester of 20:5n-3 (68.29 ± 2.15%) from the urea concentrate was attained by chromatography on argentated neutral alumina.     

板栗壳棕色素对活性氧自由基的清除作用

从清除羟基自由基和超氧阴离子自由基、抗脂质过氧化以及还原能力等方面对板栗壳棕色素的抗活性氧自由基进行了试验研究和评价,结果表明:板栗壳棕色素对 Fenton 反应产生的羟基自由基和光照核黄素产生的超氧阴离子自由基均具有较强清除作用.对脂质过氧化过程中产生的脂自由基和脂过氧化自由基有明显的抑制作用.且在试验浓度范围内,其最大清除率或抑制率分别可达到 83.0%、82.1%和 88.5%.表明板栗壳棕色素是一种优良的天然抗氧化剂和自由基清除剂.     

内乳化防离子水性聚氨酯皮革涂饰剂的研究进展

本文综述了内乳化阴离子水性聚氨酯皮革涂饰剂的性能特点,制备方法和原理以及国内外近期研究进展,指出水性聚氨酯皮革涂饰剂的发展趋势为,单一型向复合型,多功能涂饰剂发展,单组分向双组分涂饰剂过渡,双组分水性聚氨酯及改性水性聚氨酯皮革涂饰剂是近期研究的重点和热点。     

Fractionation of lipids and purification of γ-linolenic acid (GLA) from Spirulinaplatensis

The microalgae, Spirulinaplatensis, is an excellent source of γ-linolenic acid (GLA), an essential polyunsaturated fatty acid and a potent nutraceutical. The fatty acid composition of S.platensis ARM 740 was determined after transmethylation by gas chromatography (GC). Lipid fractionation was achieved on silica gel column chromatography and preparative TLC. Neutral lipids, glycolipids and phospholipids accounted for 77.0%, 15.6% and 7.4%, respectively, of the total lipid fraction. S.platensis ARM 740 was found to contain 94% of the total GLA in the glycolipid fraction. Attempts were made to purify GLA methyl ester by using urea to form inclusion complexes with the saturated and the less unsaturated FAMEs (fatty acid methyl esters), which enhanced the purity of GLA methyl ester to 84%. A further approach to isolate GLA methyl ester with higher purity involved the use of argentated silica gel chromatography. An initial PUFA concentration step frequently adopted by most researchers to increase GLA purity was not necessary in the isolation of GLA from S.platensis. A GLA methyl ester with a purity of >96% and a recovery of 66% was obtained. Purity of the isolated GLA methyl ester was confirmed by GC and IR analysis with respect to authentic standard.     

再生纸浆用阴离子分散松香施胶剂的制备

对天然松香进行强化和酯化改性,确定了再生纸浆用的松香的最佳加成量和酯化度。以常压逆转乳化法制备了阴离子分散松香胶,对乳化剂的选择和配比、用量及转相高速搅拌时间进行了研究,测定了松香胶的乳液性质和施胶效果。