三嗪类光生酸剂的合成及性能表征

以2-甲基-4,6-双（三氯甲基）-1,3,5-三嗪为原料,与取代的芳香醛类化合物经过缩合反应制备了四种三嗪类光生酸剂,其结构经1HNMRI、R等分析确认,同时对其基本物性、紫外吸收性能及在405、365nm光源下的光分解及产酸性能进行了研究。结果表明,四种三嗪类光生酸剂都有较高的热稳定性和在常用有机溶剂中有较好的溶解性。在405nm光源曝光下2-（9-蒽乙烯基）-4,6-双（三氯甲基）-1,3,5-三嗪（PAG4）的分解和产酸量子产率达到分别为10%和9%,为四者中最高;2-（4-羟基苯乙烯基）-4,6-双（三氯甲基）-1,3,5-三嗪（PAG2）几乎不分解也不产酸。在365nm光源下四种光生酸剂的分解及产酸量子产率均很低。     

罗丹明B作为试踪剂在测试光生酸剂产酸中的应用

采用一种在树脂膜中测试光生酸剂产酸量的方法,测试了膜中光生酸剂的产酸率.以罗丹明B为试踪剂,在酸性条件下罗丹明B的紫外吸收随酸浓度而变化,通过其紫外吸光度的改变来反映酸度的变化.用紫外分光光度计分别测量盐酸、三氟甲磺酸在不同浓度时罗丹明B特征吸收的变化,选取酸浓度与罗丹明的特征吸收的变化量呈线性关系的线段部分作为标准工作曲线.根据标准工作曲线及推导出的公式,通过计算就可以得出光生酸剂曝光产生的酸量.     

含光生酸酚醛树脂CTP版材成像体系研究

为了研究一种有望应用于计算机直接制版（computer-to-plate,CTP）的光敏成像版材配方,先以对甲酚和甲醛为原料合成一种交联剂,利用IR、TG进行结构表征;将它和一种线性酚醛树脂配制成涂膜液,其中分别掺加2种三嗪类光生酸剂,通过曝光、烤版、显影研究成像过程,并利用膜厚变化和表面特性变化研究成像性能。     

光皮木瓜总酸浸提和测定

通过酸碱滴定法定量，研究了光皮木瓜总酸乙醇浸提工艺。在单因素实验基础上采用L9（3^4）正交试验设计，考察了浸提时间、浸提温度、料液比、乙醇浓度等因素对光皮木瓜总酸浸提率的影响。研究结果表明，在60％乙醇中浸提温度为40℃，浸提时间为40min，料液比1：8时效果最好，总酸量为2．36mmol·g^-1．     

分光光度法测定胭脂红酸的研究

建立了分光光度法检测胭脂红酸的方法。结果表明,pH4．0浓度为1．0mol／L的磷酸钠缓冲液较适宜作胭脂红酸的溶解剂,胭脂红酸在1．251xg／mL～160μg／mL的浓度范围内的吸光度值线性相关系数达0．9997,方法回收率为104％～110％,平均相对标准偏差为0．78％－2．13％。     

辣椒粉乳酸发酵产酸条件的研究

肯定了辣椒粉乳酸发酵的可能性，揭示了发酵的适宜条件：接种量３．９０×１０９个乳酸菌／７ｇ辣椒粉，温度２５～３１℃，糖／料１：２７５。     

辣椒粉乳酸发酵产酸条件的研究

肯定了辣椒粉乳酸发酵的可能性，揭示了发酵的适宜条件：接种量３．９０×１０９个乳酸菌／７ｇ辣椒粉，温度２５～３１℃，糖／料１：２．７５。     

分光光度法测定毛酸浆果中总黄酮含量的研究

探讨建立分光光度法测定毛酸浆中的总黄酮含量的方法,通过考察显色剂用量以及加入显色剂后放置时间对毛酸浆总黄酮测定的影响,采用单因素和正交试验优化硝酸铝-亚硝酸钠比色法测定毛酸浆果中总黄酮的含量。结果表明,毛酸浆中总黄酮含量测定的最佳的条件为:5%Na NO2溶液0.8 m L,混匀放置2 min后,加10%Al(NO3)3溶液0.8 m L,混匀,继续加4%Na OH溶液6 m L,定容混匀后立即在335 nm下测其吸光度。在此条件下,芦丁标准溶液在0~0.002 4 mg/m L范围内与吸光度值间的回归方程y=289.02x+0.008,R2=0.999 5。该测定方法的平均加标回收率为100.83%,稳定性、精密度以及回收率的相对标准偏差(RSD)分别为0.34%,0.29%和2.91%。该方法简便、快速、准确,可以用于毛酸浆果汁中总黄酮含量的测定。     

Study on extraction efficiency of natural antioxidant in coffee by capillary electrophoresis with amperometric detection

Capillary electrophoresis with amperometric detection (CE-AD) has been used for the determination of catechin, rutin, ferulic acid, o-dihydroxybenzene, chlorogenic acid, caffeic acid, gallic acid, and protocatechuic acid in coffee. Comparison of extraction efficiency of antioxidants using different polar solvents was also conducted by this method. Effects of several important factors including the acidity and concentration of running buffer, separation voltage, and working electrode potential, were evaluated to obtain the optimum analysis conditions. The working electrode was a 300 um carbon disc electrode at an applied potential of +0.95 V (vs. saturated calomel reference electrode). Under the optimum conditions, the analytes can be well separated within 26 min in a 75 cm length fused-silica capillary (i.d. 2.5 × 10⁻⁵ m). The current response was linear over three orders of magnitude with detection limits (S/N = 3) ranging from 6.0 × 10⁻⁸ to 3.6 × 10⁻⁷ g/mL for all analytes.     

气相色谱法测定食品中山梨酸、苯甲酸方法

通过对液态、固液混合态食品前处理方法的改进,用气相色谱法快速测定山梨酸、苯甲酸的含量。样品酸化后用乙醚提取,直接取上清液进样分析,使用美国安捷伦公司6890型气相色谱仪,氢火焰离子化检测器(FID)和DB-FFAP123-3233色谱柱(30m×320μm)1h内可测得两种防腐剂的平均回收率为99.82%(n=6),平均相对标准偏差为1.265%,检测限为1mg/kg。     

固态发酵酒醅中微生物群落的分析鉴定方法浅析

白酒固态发酵环境开放,多种微生物共同作用以决定白酒的香型及好坏.对固态发酵中微生物群落的分析可以进一步了解白酒的形成过程,微生物的分离鉴定方法就显得尤为重要.该文主要介绍了固态发酵酒醅中微生物的主要分离鉴定方法,论述其原理并讨论各自的优缺点.     

食品反式脂肪酸检测方法研究进展

反式脂肪酸是一种具有反式构型不饱和脂肪酸,来源较为广泛;最近流行病学调查研究表明,反式脂肪酸对人体健康有很大危害,因此,世界粮农组织和世界卫生组织提出食品中反式脂肪酸含量应低于4%,欧洲各国也限定食品中反式脂肪酸含量。该文介绍近年国外反式脂肪酸检测方法研究进展,为我国反式脂肪酸检测提供参考。     

两种胡桃醌脂质体包封率测定方法研究

目的:建立两种胡桃醌脂质体包封率的测定方法,并对测定结果进行比较。方法:分别采用透析法和葡聚糖凝胶色谱柱法对脂质体中的游离药物进行分离,然后使用紫外分光光度计对脂质体包封的药物进行测定进而计算包封率。结果:透析法透析14h达到稳定;葡聚糖凝胶色谱柱法在30min内即将游离药物与脂质体进行有效的分离。胡桃醌测定波长为425nm,在0.005~0.04mg/m L的浓度范围内,线性关系良好,经回收率实验、精密度及重现性实验证实两种方法可行。结论:对比两种方法可知透析法耗时较长测定的包封率值偏低,葡聚糖凝胶色谱柱法测定所需时间更短,更便捷,测出的包封率更接近真实值。      

Effects of reduced dietary protein and supplemental rumen-protected essential amino acids on the nitrogen efficiency of dairy cows

When fed to meet the metabolizable protein requirements of the National Research Council, dairy cows consume an excess of N, resulting in approximately 75% of dietary N being lost to the environment as urine and feces. Reductions in environmental N release could be attained through an improvement in N efficiency. The objective of this study was to determine if the predicted reduction in milk yield associated with feeding a low-protein diet to lactating dairy cows could be avoided by dietary supplementation with 1 or more ruminally protected (RP) AA. Fourteen multiparous and 10 primiparous Holstein cows, and 24 multiparous Holstein × Jersey crossbred cows were used in a Youden square design consisting of 8 treatments and 3 periods. The 8 dietary treatments were (1) a standard diet containing 17% crude protein [CP; positive control (PC)], (2) a 15% CP diet [negative control (NC)], (3) NC plus RP Met (+M), (4) NC plus RP Lys (+K), (5) NC plus RP Leu (+L), (6) NC plus RP Met and Lys (+MK), (7) NC plus RP Met and Leu (+ML), and (8) NC plus RP Met, Lys, and Leu (+MKL). Dry matter intake was not affected by treatment. Crude protein intake was lower for NC and RP AA treatments compared with the PC treatment. No detrimental effect was detected of the low-CP diet alone or in combination with AA supplementation on milk and fat yield. However, milk protein yield decreased for NC and +MKL diets, and lactose yield decreased for the +MKL compared with the PC diet. Milk urea N concentrations were lower for all diets, suggesting that greater N efficiency was achieved by feeding the low-protein diet. Minimal effects of treatments on arterial plasma essential AA concentrations were detected, with only Ile and Val being significantly lower in the NC than in the PC diet. Phosphorylation ratios of signaling proteins known to regulate mRNA translation were not affected by treatments. This study highlights the limitations of requirement models aggregated at the protein level and the use of fixed postabsorptive efficiency to calculate milk protein requirements. Milk protein synthesis regulation by signaling pathways in vivo is still poorly understood.     

脂质体的制备方法及其比较

近年来,脂质体的研究是一个十分活跃的领域.由于脂质体的良好靶向性以及其长期有效等优点,它将被越来越广泛地应用于日用、生物医学等领域.以纯的磷脂为原料,选择性地采用手摇振荡法、超声法、乙醚注入法进行脂质体的制备,并对其制备效果进行了分析及比较.     

共轭亚油酸分析方法的研究进展

共轭亚油酸由含有共轭双键的亚油酸的位置和几何异构体组成,具有多种生理活性作用.综述了共轭亚油酸分析方法的研究进展,包括气相色谱、银离子高效液相色谱、气-质联用和高效毛细管电泳.选择可靠的分析方法是共轭亚油酸研究的关键.     

阿魏酸及其烷基酯在水包油乳液中抗氧化效率的假相模型解释

阿魏酸(FA)分别与乙醇、正丁醇、正辛醇和正十二醇进行直接酯化得到了4种FA烷基酯。用DPPH(1,1-二苯基-2-苦肼基自由基)法和史卡尔(Schaal)烘箱试验法分别测定了FA及其烷基酯在均相甲醇溶液和油水体积比为28的水包菜籽油乳液中的抗氧化效率。结果发现:FA在甲醇溶液中的抗氧化效率最高,其DPPH自由基清除能力为0.967mmol Trolox/mol。FA辛酯在乳液中的抗氧化效率最高,在乳化剂体积分数为1.0%下,添加了FA辛酯的乳液的共轭二烯值达到1所用的时间和p-茴香胺值达到6所用的时间分别为51,40d。用假相动力学模型测定了FA及其烷基酯在乳液界面的质量分数,结果表明,FA辛酯在乳液中的抗氧化效率最高是由于其在乳液界面的质量分数最高的缘故。