牡丹花水提液清除羟自由基及抑制酪氨酸酶活性的研究

采用水提法提取牡丹花制得牡丹花水提液,以Fenton反应产生羟自由基,比色法检测牡丹花水提液清除羟自由基的能力,分别以L-酪氨酸和L-多巴为底物,在30℃,p H=6.8的磷酸盐缓冲体系中测定牡丹花水提液对酪氨酸酶单酚酶活性和二酚酶活性的抑制效应。实验结果表明,牡丹花水提液可有效清除羟自由基,牡丹花水提液质量浓度为1.00 g·L-1时,自由基清除率达91.67%;牡丹花水提液对酪氨酸酶单酚酶和二酚酶活性均有良好抑制作用,其IC50分别为0.015和0.210 g·L-1。牡丹花水提液对二酚酶的抑制作用表现为非竞争性抑制,米氏常数(Km)为0.4 mmol·L-1。     

迷迭香、柠檬草、薄荷水提液清除羟自由基能力的研究

采用水提法提取迷迭香、柠檬草及薄荷叶片中成分制得水提液。以Fenton反应产生羟自由基,用分光光度法测定3种植物水提取液对羟自由基的清除作用。结果表明,迷迭香水提液、柠檬草水提液和薄荷水提取液对羟自由基均有显著清除作用,其中薄荷水提液的清除作用最强。含120 mg活性物的薄荷水提液样品的自由基清除率达95.66%。     

三种云南产鲜花醇提液对ABTS自由基的清除作用

以3种常见食用花卉(玫瑰花、菊花、茉莉花)为原材料,经乙醇浸提得鲜花醇提液,考察了鲜花醇提液对ABTS自由基的清除作用。结果表明,浓度为2.5mg·mL~(-1)时,玫瑰花、菊花和茉莉花醇提液对ABTS自由基的清除率分别为80.61%、93.90%和83.71%,对ABTS自由基的半数抑制浓度(IC50值)分别为1.15mg·mL~(-1)、1.02mg·mL~(-1)和1.21mg·mL~(-1),其中菊花醇提液清除ABTS自由基的能力最强。食用玫瑰花、菊花、茉莉花醇提液均对ABTS自由基具有较强的清除作用,可作为天然抗氧化剂加以开发。为开发和利用云南鲜花资源作为天然高效食品抗氧化剂提供了理论依据。     

桑白皮水提物美白机制研究

酪氨酸酶催化氧化酪氨酸的过程中需要超氧阴离子自由基的参与,通过研究桑白皮水提物的抗超氧阴离子和抑制酪氨酸酶的能力,综合评定了桑白皮水提物的美白效果;通过Lineweaver-Burk双倒数作图法确定了桑白皮水提物抑制酪氨酸酶的机制类型.实验结果显示,桑白皮水提物清除超氧阴离子自由基的能力是维生素C的1.22倍,IC50值为6.15 mg/mL;桑白皮水提物抑制蘑菇酪氨酸酶单酚酶、二酚酶的能力分别是维生素C的0.85倍和1.68倍,其抑制二酚酶的IC50值为1.53 mg/mL;桑白皮水提物属混合型抑制剂,抑制常数(KI,KIS)分别为4.34 mg/mL和23.26 mg/mL.这些数据表明,桑白皮水提物具有良好的清除超氧阴离子自由基能力以及抑制酪氨酸酶能力.     

7种云南可食用昆虫醇提液对ABTS+自由基清除作用

本文研究7种云南常见可食用昆虫对ABTS+自由基的清除作用.采用超声破壁技术提取制备7种可食用昆虫的乙醇提取物,研究加热对可食用昆虫ABTS+自由基清除能力的影响.通过线性拟合计算获得ABTS+自由基清除的半数抑制浓度IC50值.结果 表明:所测7种可食用昆虫中ABTS+自由基清除能力最强的为金蝉,最弱的为虾巴虫.7种...     

对羟基肉桂酸抑制酪氨酸酶活性的动力学研究

采用酶动力学方法研究了对羟基肉桂酸对酪氨酸酶单酚酶和二酚酶活力的抑制效应。结果表明,对羟基肉桂酸对酪氨酸酶单酚酶和二酚酶活性均有抑制作用,导致单酚酶活力和二酚酶活力下降50%的对羟基肉桂酸浓度约分别为0.12 mmol/L和0.50 mmol/L。对羟基肉桂酸能明显延长单酚酶的迟滞时间,0.2 mmol/L对羟基肉桂酸能使迟滞时间由1.1 min延长至6.2 min。对羟基肉桂酸对二酚酶的抑制作用为混合型抑制,对游离酶的抑制常数和对酶-底物络合物的抑制常数分别为0.29 mmol/L和0.60 mmol/L。     

枸杞水提物在膏霜化妆品中的应用研究

采用清除羟自由基法检测了枸杞等植物活性成分的抗氧化能力。结果显示,枸杞水提物具有很好的清除羟自由基的效果,枸杞水提物溶液在质量分数为6%时,对羟自由基的清除率达到78.77%。将枸杞水提物溶液添加到膏霜化妆品配方中,评价枸杞水提物在化妆品中的应用效果。结果表明,含枸杞水提物的护肤霜具有保湿、美白、增强皮肤弹性的作用,且对皮肤安全、无刺激性。     

睡莲花提取物对酪氨酸酶的抑制作用及其动力学研究

采用紫外分光光度计测定多巴醌,得到了睡莲花提取物对酪氨酸酶的抑制率;以L-酪氨酸为底物,采用酶动力学的方法研究了睡莲花提取物对酪氨酸酶单酚酶活性的抑制作用及抑制机制。结果表明,睡莲花提取物对酪氨酸酶具有明显抑制作用,其中30%乙醇洗脱部位抑制效果最好,其对酪氨酸酶单酚酶活性的抑制作用表现为可逆反竞争型抑制;50%乙醇洗脱部位对酪氨酸酶单酚酶活性的抑制作用表现为可逆性抑制,低浓度时为混合型,高浓度时为竞争型。     

水溶性高分子纸塑胶的研制

介绍了一种丙烯酸酯 -醋酸乙烯共聚乳液胶粘剂的制备方法 ,该胶粘剂适用于塑料瓶贴标及纸塑复合 ,具有干燥速度快 ,水溶性等特点 ,适用于机械化操作     

水溶性聚酯合成及其溶解特性研究

研究了SIPM用量和聚合反应条件对酯交换反应速度、产物分子质量的影响,考察了合成产物的结构和碱溶解特性。结果表明:SIPM用量增加,酯交换反应速度下降,当SIPM质量分数由8%增加到12%时,反应速度明显下降,产物分子质量随聚合反应体系余压减小和SIPM用量降低而增大,得到的水溶性聚酯有很好的碱可溶性,减量率随NaOH浓度增加,碱解时间延长,温度提高而增大。     

水溶性酚醛树脂制备超级电容器用活性炭

以苯酚和甲醛为原料,氢氧化钠为催化剂,采用两步碱催化合成工艺,制备了水溶性酚醛树脂前驱体。使前驱体在高温下炭化,制备出以介孔为主的活性炭。将活性炭在2.5 mol•L^-1 HNO₃溶液中进行活化后得到产品。所得产品的物理性质用红外光谱（IR）、扫描电镜（SEM）和比表面（BET）测试进行表征。结果显示活化后活性炭比表面积略有下降,平均孔径变宽,但因活化增加了活性炭含氧官能团的含量,使得活性炭表面有效比表面积增加。电化学测试结果表明活化后的活性炭电极比容量增加,达到250 F•g^-1。     

糖蜜酒精发酵浓缩液生产螯合水溶肥技术研究与应用前景

介绍在糖蜜酒精发酵浓缩液(MAWC)中添加适量中微量元素喷雾干燥制螯合水溶肥的方法,分析其应用前景。针对国内大量糖蜜酒精发酵液处理给制糖企业及环境带来的压力,应用MAWC生产螯合水溶肥可使企业、生态环境、社会多方受益。     

Evidence of gel effect and living free radicals in particles: Soap-free emulsion polymerization of styrene by using 2,2'-azobis(isobutyronitrile)

Batch, in situ seeded and stepwise dosing monomer, and normal seeded soap-free emulsion polymerizations (SFEP) of styrene were carried out by using the oil-soluble 2,2′-azobis(isobutyronitrile) as initiator. Gel permeation chromatography (GPC) and scanning electron microscopy were employed to characterize the experimental results. Typical auto-accelerative effect in the bulk free-radical polymerization was also observed in the macro-kinetics of batch SFEP at 60 and 65°C. Flat-roof GPC curves appeared at the post-auto-acceleration. In addition, $$ in particles exhibited a positive relationship with the size of particles. The bigger size the larger $$. In the in situ seeded polymerization, the flat-roof GPC curves of seed turned into the asymmetric Gaussian type exhibiting the great increase of the fraction of larger $$ with the sequential addition of styrene. In addition, the number of seeds was kept constant throughout the polymerization. It indicated that the free radicals were generated and confined in the growing particles. In the normal seeded polymerization, $$ showed a strong dependence on the average assigned amount of St per seed particle. The more monomers per seed particle the larger $$ was gained. Based on these results, it was postulated that the free radicals were living due to the gel effect occurring in particles, namely that the free radicals were segregated by the dry polymer chains. The kinetics model was also given based on the microdroplets theory.     

帆布-聚氨酯泡沫粘合用交联型聚丙烯酸酯水溶胶的研究

用半连续法合成了一种帆布-聚氨酯泡沫粘合用交联型聚丙烯酸酯水溶胶,讨论了交联单体用量及配比、外加交联剂的用量及固化温度等因素对胶黏剂性能的影响。研究表明交联单体用量约为4.0%,制得的胶黏剂性能优良,若外加千分之四的交联剂,在110℃下烘干固化,可显著提高该胶黏剂的耐水性。     

The importance of electrode material in environmental electrochemistry: Formation and reactivity of free hydroxyl radicals on boron-doped diamond electrodes

A model describing the hydroxyl radical (HO) concentration profile at the boron-doped diamond (BDD) electrode, in the presence and absence of organic compounds, is presented. It is shown that this profile depends strongly on the reaction rate constant between the HO and the organic compound. Furthermore, it is shown that the presence of organics affects the current-potential (I-V) curves. In fact, the higher the reaction rate between organics and HO, the higher is the shift of the I-V curves toward lower potential with respect to oxygen evolution. Supposing that water discharge to free hydroxyl radicals on BDD is governed by Nernst equation, this shift of the I-V curves toward lower potentials has been calculated and compared with the experimental data obtained on BDD using two model compounds: methanol and formic acid.     

Multivariate model for the prediction of soluble condensed tannins in crude extracts of polyphenols from canola and rapeseed hulls

The feasibility of using ultraviolet spectrophotometry to develop multivariate models for prediction of soluble condensed tannins (SCT) content in crude polyphenols extracts from canola and rapeseed hulls was investigated. The polyphenols were extracted from hulls using 70% (vol/vol) aqueous acetone. Partial least squares regression was used to correlate the spectral data of the crude polyphenols in methanol between 265–295 nm with the SCT content in hulls. Both the proanthocyanidin (P) and the vanillin (V) assays were used to provide reference data for creating the models. The predictive ability of the models is good, as indicated by the RPD values [the ratio of the standard deviation of data to the standard error of calibration (SEC) of above 5. Additionally, the SEC values suggest that P is superior to V in predicting the SCT content of hulls using this method.     

Phase equilibrium data on carbon dioxide hydrate in the presence of electrolytes,water soluble polymers and montmorillonite

Equilibrium formation conditions for carbon dioxide hydrate were measured in pure water and in aqueous polymer and electrolyte solutions. The solutions that were used include: polyethylene oxide, partially (10 and 90 percent) hydrolyzed polyacrylamide, sodium chloride and calcium chloride. Experiments with solutions containing both electrolyte and polymers were also performed. It was found that the electrolytes exhibited a substantial inhibiting effect whereas the polymers only slightly altered the equilibrium hydrate formation conditions. The measured equilibrium formation pressures were compared with the predictions from existing hydrate equilibria methods and were found to be in good agreement. The effect of montmorillonite was also studied and it was found that it did not affect the equilibrium hydrate formation conditions. A total of 101 experimental measurements are reported.