γ-聚谷氨酸的絮凝活性研究

利用枯草芽孢杆菌通过发酵生产得到γ-聚谷氨酸,再经过提取纯化得到纯品.γ-聚谷氨酸作为一种新型的微生物絮凝剂,具有用量少、无污染等优点.通过研究表明,最佳絮凝介质为1g/L的高岭土溶液,γ-聚谷氨酸的浓度为0.2 g/L时絮凝活性最好,最佳絮凝条件为自然pH值和室温,最佳的助凝离子是Cu2+,当Cu2+的浓度为0.2 mol/L时助凝效果最好,此外γ-PGA比聚丙烯酰胺具有更好的絮凝活性,对花园土的絮凝率能达到32.1%.     

生物降解型聚谷氨酸的研究进展

新型生物可降解高分子材料聚谷氨酸(Polyglutamic acid,PGA)及其衍生物作为药物载体的应用研究近年来颇受医学界和生物界的关注。聚谷氨酸是由L-谷氨酸,或D-谷氨酸通过肽键结合而形成的一种多肽高分子。这种高分子在自然界或人体内可以生物降解成内源物质谷氨酸Glu,不易产生积蓄和毒副作用。它的分子链上具有较多的侧链羧基(—COOH),易于和一些药物结合生成稳定的复合物,是一种理想的体内可生物降解的医药用高分子材料。近年来,经大量研究,人们认定,聚谷氨酸及其衍生物作为一种新型缓/控释给药系统,它具有事先设计给药剂量,控制药物释放的时间,以及降低药物毒性等优点。本文对聚谷氨酸的制备及在各领域的应用作了总结和评述,并对其应用前景作了进一步展望。     

聚乙二醇-聚乳酸-聚谷氨酸苄酯共聚物的合成

利用乳酸和γ-谷氨酸苄酯分别合成了乳酸氧酸酐(LacOCA)和谷氨酸苄酯氮酸酐(BLG-NCA),然后在室温下用二甲氨基吡啶(DMAP)催化LacOCA、BLG-NCA和聚乙二醇单甲醚(MPEG)开环聚合,合成聚乙二醇-聚乳酸-聚谷氨酸苄酯的三元共聚物,用核磁、GPC等方法对共聚物进行了表征.该聚合物综合了聚醚、聚酯、聚氨基酸的性能,改善了聚氨基酸的溶解性.为聚酯-聚醚-聚氨基酸共聚物的合成提供一种新思路.     

两种聚多肽材料的合成及其结晶结构研究

本文利用L-谷氨酸苄酯和L-赖氨酸苄酯分别与三光气反应合成N-羧基- L-谷氨酸g-苄酯环内酸酐(NCA)和N-羧基-L-赖氨酸g-苄酯环内酸酐,用三乙胺作为引发剂,引发NCA进行开环聚合,合成了聚谷氨酸苄酯与聚谷氨酸赖氨酸苄酯共聚物。利用核磁共振仪 (1H-NMR)、傅里叶变换红外光谱(FTIR)、凝胶渗透色谱(GPC)及X射线衍射仪(1D-WAXD)等方法对单体、聚合物的分子结构以及结晶性能进行了表征。     

一种新型生物高分子材料的研究与探索

本文系统地介绍了新型生物可降解高分子材料--γ-聚谷氨酸的性质及其研究进展.同时针对国内γ-聚谷氨酸生产成本高及发酵中试放大难的问题,介绍了本研究所如何实现微生物发酵工业化生产γ-聚谷氨酸.在最优发酵条件下,分析了200L规模下γ-聚谷氨酸的发酵过程.     

聚谷氨酸及其衍生物在新型药物传输系统中的应用

聚谷氨酸是生物可降解的高分子材料,作为新型药物载体具有广泛的用途。综述了聚谷氨酸及其衍生物在改善药物的水溶性、降低毒性、控制药物释放以及提高药物靶向性等方面的研究,为药物新剂型的开发提供参考。     

添加剂对聚谷氨酸-明胶生物胶胶凝和组织粘附性的影响

考察不同添加剂对水溶性碳化二亚胺(WSC)交联的γ聚谷氨酸-明胶生物胶胶凝和组织粘附性的影响。通过添加不同浓度的添加剂,测定γ-聚谷氨酸-明胶生物胶胶凝时间和组织粘连强度。结果表明尿素是一个能够防止明胶和γ-聚谷氨酸混合水溶液自发物理胶凝的理想添加剂,添加适量的尿素,不会改变WSC交联的γ-聚谷氨酸-明胶生物胶的胶凝和组织粘附性。     

超声波在γ-聚谷氨酸发酵工艺中的应用

考察了枯草杆菌液体发酵过程中施加超声波刺激对γ-聚谷氨酸合成的影响,并对超声波辅助水提法提取固体基质中γ-聚谷氨酸的效果进行了研究。结果表明,超声波在适当条件下刺激枯草杆菌,对其液体发酵合成γ-聚谷氨酸有明显促进作用。当枯草杆菌培养12 h后,在37℃、50W超声功率下连续辐照1 h,γ-聚谷氨酸产量提高了24.76%。超声波辅助提取γ-聚谷氨酸的提取率比常规工艺提高30%以上。优化的超声提取工艺条件为:超声波功率40 W,温度为70℃下浸提30 min。     

γ-聚谷氨酸降解影响因素及其生物降解性能的研究

为开发制备低相对分子质量γ-聚谷氨酸的最佳方法，在不同温度、pH值条件下水解γ-聚谷氨酸，利用凝肢色谱法测定不同水解时间的相对分子质量，实验表明：高温和偏酸或偏碱环境均有利于γ-聚谷氨酸的降解，最优的降解条件为低pH的酸性环境下高温加热；采用TOC法研究γ-聚谷氨酸的生物降解性能，其10d降解率在30％以上，28 d降解率在70％以上，参照OECD 301标准，属于易生物降解高分子聚合物。     

聚电解质复合物对苹果汁澄清效果的研究

研究了壳聚糖-聚谷氨酸聚电解质复合物对苹果汁饮料澄清体系的影响.针对壳聚糖-聚谷氨酸聚电解质复合物进行表征,分别采用单因素和正交试验设计分析对果汁澄清工艺进行优化,通过透光率的大小,评估壳聚糖-聚谷氨酸复合物对苹果汁澄清的影响程度.研究结果表明,苹果汁的最佳澄清工艺为反应温度50℃,聚合物添加量2. 0 mL,絮凝时间30 min.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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