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《中国洗涤用品工业》2018,(4)
正(上接2018年第2期第63页)15温和度评估方法研究人员开发了体外各种蛋白质变性实验来预测表面活性剂对眼睛和皮肤刺激性情况(Paye,1999)。玉米醇溶蛋白(Zein)测试是一种广泛应用的体内筛选方法,用于评价局部对表面活性剂的容忍度。玉米醇溶蛋白可从玉米和角蛋白中获取。该实验方法是由Gotte发明的(Gotte,1966),是基于玉米蛋白的溶解性,该蛋白一般不溶于水,除非蛋白变性。在常温下将该蛋白与表面活性剂溶液 相似文献
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为了进一步提高玉米醇溶蛋白膜作为生物可降解材料的机械力学性能,改善其柔韧性和耐水性,研究了不同增塑剂(油酸、硬脂酸、聚乙二醇400)对玉米醇溶蛋白成膜性能的影响。对各种改性增塑蛋白膜的质构分析、表面结构观察和热力学分析的结果表明:添加3%(体积分数)的油酸可使膜的抗拉强度提高30%、伸长率提高20倍,柔韧性大为提高,吸水率降低2倍以上,而且膜的表面结构更加光滑。 相似文献
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利用鞘氨醇杆菌(Sphingobium sp.)对硝酸氧化的低阶煤进行降解,并利用紫外-可见分光光度计、气相色谱-质谱联用仪和红外光谱仪对生物降解过程中煤与降解液的化学组成以及降解产物的有机组分进行表征,对生物降解效果和降解机理进行分析。结果表明:鞘氨醇杆菌对煤的降解率达到32%,降解过程中降解液pH值不断升高,最高达到9.0;鞘氨醇杆菌的胞外液对煤具有显著的降解作用,且胞外液对煤的降解率与初始pH值密切相关;高温加热后的胞外液对煤的降解效果明显降低。红外光谱分析结果显示,经鞘氨醇杆菌降解后煤中的羧基官能团和硝基官能团含量明显降低;气相色谱-质谱联用分析结果显示,降解产物主要含有羧酸、醇、醛、酚和杂环类化合物,其中脂肪酸含量最多。鞘氨醇杆菌可通过产生胞外酶和碱性物质对义马低阶煤进行高效降解,降解产物中含有丰富的脂肪酸,经生物降解后煤中氧含量明显降低。 相似文献
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为了提高壳聚糖/玉米醇溶蛋白膜的机械性能,将壳聚糖液与玉米醇溶蛋白液共混,向其中加入0%、15%、30%、45%(w/w)的油酸改性,研究膜液的粒径、zeta电位、静态和动态流变特性;然后,分析油酸添加量对膜阻隔性能,机械性能和相容性的影响。结果表明:添加油酸后,膜液体系粒径增大、分散均匀,添加30%油酸的膜液分散性更好,PDI为0.34,粒径为1307.5nm。随着油酸含量增大,膜液粘度减小,流动指数增大,弹性模量和粘性模量增加。OA-30膜机械性能较好,抗拉强度达到36.37MPa,断裂延伸率达到22.32%。膜的阻隔性增强,水蒸气、氧气透过率分别降低了44.21%和66.52%。复合膜中壳聚糖与玉米醇溶蛋白分子相容性好,表面光滑平整。综上所述,油酸改性改善了壳聚糖/玉米醇溶蛋白复合膜性能。 相似文献
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为提高阿维菌素叶面沉积率及其抗紫外分解性能,本文设计构建了叶面亲和的纳米载体。通过自由基聚合将聚二甲基二烯丙基氯化铵(PDMDAAC)改性玉米醇溶蛋白(Zein),得到表面携带正电荷的改性玉米醇溶蛋白,并将其用于负载阿维菌素。采用红外光谱(FTIR)、扫描电镜(SEM)等手段对改性产物结构和形貌进行表征。通过反溶剂沉淀法制备了平均粒径为64.92nm的载药纳米粒子,载体对阿维菌素的包封率为(34.75±0.18)%。与植物表面的静电作用提升了纳米粒子悬浮液在植物表面的润湿性能,接触角大小随PDMDAAC接枝量增大而降低,由77.38°减小到64.60°;叶面滞留量可达33.69mg/cm2。改性玉米醇溶蛋白对阿维菌素的包覆提升了其抗紫外性能,半衰期由15min延长至40min,且阿维菌素的释放速率可通过PDMDAAC接枝率进行调控。 相似文献
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美国农业研究服务( ARS)东方研究中心已开发出一种用玉米廉价生产可以生物降解的保护性涂层的方法。生产的原料是玉米醇溶蛋白——一种在玉米谷粒中发现的蛋白质。涂层的主要用在涂敷糖果和水果(用于延长存放期),取代石蜡涂层用于纸张。与蜡不同的是,该涂层可以用酶脱除,使纸张易于回收利用。使用时,先溶解在乙醇溶液中,然后喷雾,这样玉米醇溶蛋白对纸张具有“极好”的粘着性。玉米醇溶蛋白是一种湿法粉碎得到的产品,目前以玉米面筋面为原料限量生产。 美国开发出用玉米生产涂层的工艺@郑元昌 相似文献
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将农药降解酶与多元醇类保护剂、生物防腐剂和缓冲剂等原料按照一定比例混合,制备成为农药降解酶制剂。气相色谱检测结果表明:用该农药降解酶制剂浸泡果蔬10min,其对两种目标农药对硫磷和毒死蜱的降解率分别达到了99.9%和68.3%。该农药降解酶制剂在25℃条件下密封放置12个月,酶活性损失率仅为8.91%,表现出良好的酶活稳定性。该农药降解酶制剂可以有效降解果蔬表面农药残留,具有降解效率高、安全、使用方便等特点,可以有效保障食品安全,具有广阔的市场前景。 相似文献
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CdSe量子棒是一种具有良好光学特性的半导体纳米材料,不同长径比的量子棒可应用于光电材料及器件制备。采用高温油相合成法制备CdSe量子棒,在只改变前体反应时间的前提下,探究其对于CdSe量子棒长径比的变化机理并对其光学特性进行对比分析。实验结果表明CdSe量子棒随着反应时间的增长粒径增大并且发射峰的峰位产生了红移的现象。通过透射电子显微镜表征后发现量子棒随着前体反应时间的增加长度逐渐变长,长径比逐渐变大。因此可以用该方法可以控制量子棒的生长。 相似文献
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《国际聚合物材料杂志》2012,61(8):587-595
The in-vitro degradation behavior of poly(glycolic acid) (PGA) rods and the composite rods containing poly(L-lactic acid) (PLLA) were investigated via mass loss, pH value change, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Since the degradation rate of PLLA is lower than that of PGA, PLLA/PGA composite rods exhibit a slower degradation rate in comparison with PGA. This finding indicated that it was possible to control the degradation rate of the composites by changing their composition. This result indicates that this kind of composite biomaterial may be applicable to devices for the need of prolonged degradation. 相似文献
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Edible zein-based films containing lysozyme(LY) and ascorbic acid(AA) were developed in the presence of polyethylene glycol 400(PEG 400), the combined effects of LY and AA on the microstructure, mechanical properties and release properties of developed zein films were investigated in detail. The results of microstructure characterization indicated that zein-based films became compact and smooth, and LY aggregates were well distributed in the zein matrix because of the simultaneous addition of LY and AA. The results of mechanical tests showed that because of the synergistic effects of LY and AA on zein film, elongation at break of zein-based film could be up to 138%, which was 34.5 times higher than that of zein control film. LY release tests showed that when the concentration of AA was less than 3.1 mg·cm~(-2), the release rate of LY significantly decreased by 33.7%, and the total release increased by 80.6%. While the release profiles of AA showed that the release rate and total release of AA from the films containing LY increased by approximately 68.9% and 61.7% than the films without LY. Good antioxidant and sustained antimicrobial activities were found for the developed zein films. 相似文献
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Tanta-Verona Nicolescu Walid Meouche Catherine Branger André Margaillan Andrei Sarbu Dan Donescu 《Journal of Polymer Research》2012,19(12):1-12
Copolymers of (D,L-lactide-random-ε-caprolactone)-block-poly(ethylene glycol)-block-(D,L-lactide-random-ε-caprolactone) (PLECs) were synthesized with varied D,L-lactide (LA) content and different molecular weights (20 and 50 kDa). Polymer ratios, particularly the content of LA, had significant effect on the release of trypan blue. A lower trypan blue release rate was observed from monolithic rods composed of PLECs with higher CL/LA ratio. High LA content in polymer rod led to increase of the hydrophilicity of the polymer rod and the decrease of CL content resulted in the increase of the hydrophilicity of PLECs and hydrolysis rate. Spin-coating technique was employed to coat PCL-b-PEG-b-PCL membrane on PLEC rod with controlled thickness. Results showed that membrane encased rods can produce different release pattern including delayed release, zero-ordered release and burst release depending on the types of inner rod and membrane. Results for this study indicated that PLEC rods could provide the zero-order release profile of highly water-soluble molecules. Moreover, the longer lag phase was observed at higher thickness. These results suggest that these polymer rods were potential drug delivery systems that can provide controlled drug release profiles. 相似文献
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分别采用2种酸1种醇和2种醇1种酸分别对聚丁酸丁二醇酯(PBS)改性,合成了不同化学结构的共聚酯聚(丁二酸丁二醇酯-co-己二酸丁二醇酯)(PBSA)和聚(丁二酸丁二醇-co-丁二酸己二醇酯)(PBSH),并在磷酸缓冲液以它们为底物在磷酸缓冲液中,研究了对脂肪酶N435降解反应感受性的异同。采用质量损失率和凝胶渗透色谱评价了降解前后共聚酯相对分子质量的变化;广角X衍射仪和热重分析仪分析了酶降解前后共聚酯结晶度和热性质的变化;偏光显微镜对降解后的材料进行了形貌观测。结果表明,相比于PBS,PBSA和PBSH对脂肪酶的感受性有很大提高,24 h后降解率分别达到90 %和60 %以上,并且PBSA降解速率比PBSH快;降解后两种共聚酯相对分子质量变化不大,但相对分子量分布系数变宽,结晶度增大;降解3 d后PBSA的热稳定性降低,而PBSH的热稳定性提高。 相似文献
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Microwave-Assisted Synthesis of Titania Nanocubes, Nanospheres and Nanorods for Photocatalytic Dye Degradation 总被引:1,自引:0,他引:1
T. Suprabha Haizel G. Roy Jesty Thomas K. Praveen Kumar Suresh Mathew 《Nanoscale research letters》2009,4(2):144-152
TiO2 nanostructures with fascinating morphologies like cubes, spheres, and rods were synthesized by a simple microwave irradiation
technique. Tuning of different morphologies was achieved by changing the pH and the nature of the medium or the precipitating
agent. As-synthesized titania nanostructures were characterized by X-ray diffraction (XRD), UV–visible spectroscopy, infrared
spectroscopy (IR), BET surface area, photoluminescence (PL), scanning electron microscopy (SEM) and transmission electron
microscopy (TEM), and atomic force microscopy (AFM) techniques. Photocatalytic dye degradation studies were conducted using
methylene blue under ultraviolet light irradiation. Dye degradation ability for nanocubes was found to be superior to the
spheres and the rods and can be attributed to the observed high surface area of nanocubes. As-synthesized titania nanostructures
have shown higher photocatalytic activity than the commercial photocatalyst Degussa P25 TiO2. 相似文献
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以聚丁二酸丁二酯(PBS)薄片为降解底物,利用角质酶对其进行降解研究,考察PBS的酶促降解行为。利用扫描电子显微镜、差示扫描量热仪和热重分析仪等方法对降解前后的PBS薄片进行了表征分析,并进一步采用质谱仪对降解产物进行分析。结果表明,在酶浓度2.5 U/mL、反应温度37 ℃以及pH 7.4的条件下,经16 h降解PBS薄片的降解率可达93.88 %,在降解时间为2 h时有最大降解速率32.97 μg/cm2·h;PBS薄片有片层脱落降解的现象,促进了角质酶的降解作用;随降解时间的延长,PBS相对结晶度逐渐降低,热稳性也呈现下降趋势;PBS被降解成单体或寡聚物。 相似文献
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以钛酸四丁酯为前驱体,冰醋酸为水解抑制剂,采用溶胶-凝胶法制备纳米TiO2/CNTs复合催化剂。测定复合催化剂对不同浓度茜素红溶液的光降解活性,并对光催化降解动力学进行研究。结果表明,在CNTs负载质量分数7.5%、焙烧温度450 ℃和焙烧时间3.5 h条件下制备的TiO2/CNTs复合催化剂光催化活性得到提升。相同条件下,TiO2/CNTs对150 mg·L-1茜素红溶液的最终降解率达67%,而TiO2的最终降解率只有56%。复合催化剂光催化活性提升的原因是CNTs负载后光催化粒子在紫外光照射下生成更多的氢氧根活性自由基。光催化降解动力学符合Langmuir-Hinshelwood方程,催化剂对污染物的表观吸附是整个反应的“瓶颈”。随着反应浓度的增大,光催化降解反应的反应级数由一级反应逐渐下降为零级反应。 相似文献