共查询到20条相似文献，搜索用时 437 毫秒
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综述了玉米芯中木聚糖提取工艺的研究现状。不同的研究结果表明,不同条件下玉米芯中木聚糖的提取率各有差异。多数情况下,传统的碱法提取和蒸煮法提取等工艺中,木聚糖的提取率在18％-28％之间;采用微波辅助法,木聚糖的提取率可达3％左右。比较微波辅助提取与常规法提取可以看出,两者的木聚糖提取率相差不大。但微波辅助能够大大缩短提取时间,降低提取温度,使木聚糖提取过程更容易。 相似文献
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目的 :探讨氦氖激光对 Na Cl溶液、葡萄糖溶液粘度的影响。方法 :以特定的激光强度、经不同的照射时间处理溶液 ,用奥氏粘度计测定溶液的粘度。结果 :激光对蒸馏水和 Na Cl溶液粘度无明显影响 ,激光使葡萄糖溶液粘度比对照组降低 ,但差异不显著 ( P>0 .0 5 )。结论 :氦氖激光对葡萄糖溶液粘度有一定的影响。 相似文献
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《华夏星火》1997,(5)
几丁质又名壳多糖、甲壳质、甲壳素。昆虫、甲壳类(虾、蟹)等动物的外骨骼主要由壳多糖与碳酸钙组成,在虾壳等软壳中,含几丁质15％～40％,碳酸钙30％～40％;在蟹壳类等硬壳中,含几丁质15％～20％,碳酸钙约75％;蛆壳是纯度极好的几丁质含量达95％以上;一些霉菌的细咆壁成分中,也有几丁质。壳多糖是N-乙酰-2-氨基葡萄糖以β—1,4苷键连接而成的多糖,基本结构单位是壳二糖单位。在通常的条件下,几丁质不能被生物降解,不溶于水和稀酸,也不溶于一般的有机溶剂。将甲壳用碱脱去乙酰基后,就生成几丁质。食品工业及水产加工地区有大量虾皮、蟹壳等下脚料,可以利用来提取几 相似文献
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目的 :探讨氦氖激光对蒸馏水、自来水粘度的影响。方法 :以特定的激光强度、经不同的照射时间处理溶液 ,用奥氏粘度计测定溶液的粘度。结果 :氦氖激光对自来水粘度的影响随照射时间的不同呈双向结果 ,照射时间在 1 0 min以内粘度低于对照组 ,差异显著 ( p<0 .0 5 ) ,照射时间超过 1 0 min,粘度高于对照组 ,差异显著 ( p<0 .0 5 ) ,对蒸馏水粘度无明显影响。结论 :氦氖激光对自来水粘度有一定的影响。 相似文献
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针对当前稀溶液流经毛细管使溶液中分子吸附在管壁上,导致稀溶液粘度测量准确度不高,从而影响毛细管两端不同压强差对稀溶液粘度测量影响分析准确性,提出一种基于哈根-泊肃叶定律的毛细管两端不同压强差对稀溶液粘度测量的影响分析方法,以毛细管粘度计非计时刻度线区的液位检测信息为先验知识,利用罗曼诺夫斯基准则,确定毛细管粘度计非计时刻度线区向计时刻度线区过渡的特征点,并利用模糊判决调整液位检测电压的采样时间间隔,并以此特征点作为拟合起点,对采集到的数据进行预处理,保证分析的准确性。在此基础上,利用哈根-泊肃叶定律,根据稀溶液流过时间测定之前和之后纯溶剂在乌氏粘度计中流过的时间,证明稀溶液粘度测量过程中,分子会吸附在毛细管的管壁上,吸附层厚度与分子量无关,从而对稀溶液粘度进行计算,实验结果表明,所提方法能够准确对稀溶液粘度进行测量,测量的精确度较高,能够准确分析出毛细管两端不同压强差与稀溶液粘度之间关系。 相似文献
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均相和非均相高级氧化技术处理水中有机污染物的研究 总被引：1，自引：0，他引：1
以UV/H2O2均相高级氧化技术及TiO2光电催化非均相氧化技术为例,选择硝基苯、4-硝基苯酚、喹啉和活性艳橙K-R等为目标化合物,对高级氧化技术处理水中有机污染物进行了研究.研究表明,UV/H2O2体系中产生的·OH是硝基苯、4-硝基苯酚和喹啉降解的直接原因,有机物的降解可用准一级动力学进行很好的描述.系统研究了溶液pH值、氧化剂浓度及水体中存在的常见无机阴离子如HCO-3、NO-3、Cl-等对有机物降解的影响;探讨了各有机物的降解途径.建立了一种新的三维光电填充床催化反应器,结果表明,三维电极的使用,可以显著提高有机物的光催化氧化效率.外加电压和溶液中NaCl对活性艳橙K-R和喹啉的氧化起着促进作用;同时还研究了溶液酸度条件、空气流速及氧气对光电催化的影响. 相似文献
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D-氨基葡萄糖盐酸盐和壳聚糖都为甲壳素的衍生物，两者具有良好的相容性，并且D-氨基葡萄糖盐酸盐具有抗炎、抗反应性等作用，通过两者共混期望减少膜植入后引起的炎症。实验表明，加入D-氨基葡萄糖盐酸盐后的壳聚糖基膜的降解速度大大提高，比壳聚糖／明胶膜的降解要快。 相似文献
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壳聚糖固定化血红蛋白氧载体的制备和性能研究 总被引：1，自引：0，他引：1
以固定化血红蛋白为核心的氧载体研究，有望为航空航天、水下作业以及好氧生物发酵工业等领域提供有效的供氧体系。以猪血红蛋白（pHb）和壳聚糖微粒为氧载体制备的基本原料，采用戊二醛活化将pHb共价固定在壳聚糖微粒上，构成pHb氧载体。研究了活化条件与载体表面醛基形成量及蛋白固定量之间的相互关系，对固定化反应进行了优化。在5％戊二醛浓度下活化反应8h，获得pHb最大固定量约800mg/g，即每克截体固定800mg pHb。从pHb氧载体的氧释放曲线可知，氧释放效率可达40％左右。该氧载体的结合稳定性较好。 相似文献
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壳聚糖三维材料的制备及其应用研究进展 总被引：1，自引：0，他引：1
在生物材料的研究领域中,有关壳聚糖材料的制备与应用研究越来越受到重视,由于壳聚糖特殊的结构与性能导致壳聚糖三维材料的制备极其困难。本文着重介绍近年来壳聚糖三维材料制备研究的进展,重点是为三维壳聚糖无机复合材料、三维壳聚糖磁性功能材料、三维壳聚糖增强材料、三维壳聚糖仿生材料以及三维壳聚糖组织工程支架材料的研究进展及各材料的性能与应用方向;展望了壳聚糖三维材料的发展前景,特别是提高壳聚糖三维材料的力学性能以及在人体内环境下力学性能的耐衰减能力,在生物可降解骨折内固定材料与生物可降解骨组织工程的应用上起着决定作用,将是未来几年壳聚糖三维材料研究的重点和突破口。 相似文献
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The successful encapsulation of human hepatocellular carcinoma (HepG2) cells would greatly assist a broad range of applications in tissue engineering. Due to the harsh conditions during standard chitosan fiber fabrication processes, encapsulation of HepG2 cells in chitosan fibers has been challenging. Here, we describe the successful wet-spinning of chitosan-alginate fibers using a coaxial flow microfluidic chip. We determined the optimal mixing conditions for generating chitosan-alginate fibers, including a 1:5 ratio of 2% (w∕w) water-soluble chitosan (WSC) solution to 2% (w∕w) alginate solution. Ratio including higher than 2% (w∕w) WSC solution increased aggregation throughout the mixture. By suspending cells in the WSC-alginate solution, we successfully fabricated HepG2 cell-laden fibers. The encapsulated HepG2 cells in the chitosan-alginate fibers were more viable than cells encapsulated in pure alginate fibers, suggesting that cross-linked chitosan provides a better environment for HepG2 cells than alginate alone. In addition, we found that the adhesion of HepG2 cells on the chitosan-alginate fiber is much better than that on the alginate fibers. 相似文献
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以改性壳聚糖分子为基体,采用分子印迹技术合成了对有机磷农药久效磷有选择性的聚合物,并得到了相应的标准曲线。 相似文献
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以壳聚糖为母体,合成了携带β-环糊精侧基的壳聚糖大分子主体化合物(CDCS).通过红外光谱、X-射线衍射和浓硫酸降解等方法对CDCS进行了表征;并利用X-射线衍射和紫外-可见吸收光谱等分析方法研究了CDCS分别与二茂铁和二茂铁苯酮酸的主客体相互作用.结果表明,带有二茂铁基团的客体与壳聚糖主体化合物侧链上固载的环糊精主体确实发生了主客体相互作用. 相似文献
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二元驱地面工艺的核心技术是控制聚合物溶液的粘度损失率,粘度损失率增加会导致驱油效果下降,同时增加运行成本。通过对二元驱地面工程配注水质的筛选和优化,采用软化工艺去除水中的铁离子、钙离子和镁离子,减少上述离子对聚合物的化学剪切,可以有效降低二元驱注入体系的粘损,提高注入体系粘度。 相似文献
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Particle focusing is an essential step in a wide range of applications such as cell counting and sorting. Recently, viscoelastic particle focusing, which exploits the spatially non-uniform viscoelastic properties of a polymer solution under Poiseuille flow, has attracted much attention because the particles are focused along the channel centerline without any external force. Lateral particle migration in polymer solutions in square channels has been studied due to its practical importance in lab-on-a-chip applications. However, there are still many questions about how the rheological properties of the medium alter the equilibrium particle positions and about the flow rate ranges for particle focusing. In this study, we investigated lateral particle migration in a viscoelastic flow of DNA solution in a square microchannel. The elastic property is relevant due to the long relaxation time of a DNA molecule, even when the DNA concentration is extremely low. Further, the shear viscosity of the solution is essentially constant irrespective of shear rate. Our current results demonstrate that the particles migrate toward the channel centerline and the four corners of a square channel in the dilute DNA solution when the inertia is negligible (elasticity-dominant flow). As the flow rate increases, the multiple equilibrium particle positions are reduced to a single file along the channel centerline, due to the elasto-inertial particle focusing mechanism. The current results support that elasto-inertial particle focusing mechanism is a universal phenomenon in a viscoelastic fluid with constant shear viscosity (Boger fluid). Also, the effective flow rate ranges for three-dimensional particle focusing in the DNA solution were significantly higher and wider than those for the previous synthetic polymer solution case, which facilitates high throughput analysis of particulate systems. In addition, we demonstrated that the DNA solution can be applied to focus a wide range of particle sizes in a single channel and also align red blood cells without any significant deformation. 相似文献
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The present work aims to study the effects of the blood-microstructure on the electrical conduction from two different but correlated properties: Electrical and mechanical (viscosity), and to derive useful parameters for the evaluation of electrical conduction as a function of the blood viscosity. ac-conductivity and dielectric constant of normal and diabetic blood are measured in the frequency range 10 kHz–1 MHz at the room temperature. An empirical relation relating the resistivity and viscosity of the blood has been presented. The results show that a microfluidic device is a viable and simple solution for determination of electrical and rheological behaviors of blood samples. 相似文献
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In this article, the authors present the fabrication of an enzyme-entrapped alginate hollow fiber using a microfluidic device. Further use of enzyme-entrapped alginate hollow fibers as a biocatalytic microchemical reactor for chemical synthesis is also deliberated in this article. To ensure that there is no enzyme leaching from the fiber, fiber surfaces were coated with chitosan. To confine the mobility of reactants and products within the porous hollow fibers the entire fibers were embedded into a transparent polydimethylsiloxane (PDMS) matrix which also works as a support matrix. A vanadium-containing bromoperoxidase enzyme isolated from Corallina confusa was used as a model enzyme to demonstrate the use of these alginate hollow-fiber reactors in bromo-oxidation of phenol red to bromophenol blue at different dye flow rates. Stability of the entrapped enzyme at different temperatures and the effect of the chitosan coating on the reaction conversion were also studied. It was observed that molecules as big as 27 kDa can be retained in the matrix after coating with chitosan while molecules with molecular-weight of around 378 Da can still diffuse in and out of the matrix. The kinetic conversion rate in this microfluidic bioreactor was more than 41-fold faster when compared with the standard test-tube procedure. 相似文献