生物医用聚乳酸纤维增强壳聚糖棒材

利用原位沉析法制备了聚乳酸纤维/壳聚糖复合棒材,对复合棒材的微观形貌、力学性能进行了表征.有机聚乳酸纤维和有机壳聚糖基体具有良好的相容性,纤维表面还会因氢键等作用和基体产生物理吸附及一定的分子链缠结,SEM结果表明,纤维与基体间形成了良好的界面作用.复合棒材因聚乳酸纤维的加入有效地提高了弯曲强度和模量.当添加8%(质量分数)11 mm长的纤维时,复合材料弯曲强度达到108.9 MPa,比壳聚糖提高了54.9%,复合棒材弯曲模量达到4.74 GPa,比壳聚糖提高了170.9%.聚乳酸纤维和壳聚糖均具有良好的生物相容性和可降解性,这种复合材料在可吸收内固定材料方面将具有广阔的用途.     

pH敏感型聚乙烯醇/壳聚糖互穿网络水凝胶的溶胀及载药释药性能研究

以聚乙烯醇(PVA)和壳聚糖(CS)为原料,采用物理交联与化学交联相结合的工艺,即通过循环冷冻—解冻法结合京尼平交联法,制备了具有互穿网络结构(IPN)的PVA/CS复合水凝胶,研究了pH值对其溶胀率的影响;选用氯霉素为模型药物,探讨了PVA/CS水凝胶在模拟胃液(SGF)和模拟肠液(SIF)中的载药、释药性能.结果表明,PVA/CS IPN水凝胶在酸性条件下具有较高的溶胀率,而在碱性条件下,溶胀率较小;其载药量、释药量都随着复合水凝胶中PVA含量的增大而增大;且在SGF中的药物释放率高于SIF的释放率;在SGF中的药物释放速率随着组分中PVA含量的增加而增大.     

羟丙基壳聚糖-聚乙烯醇凝胶的制备与释药性能

以羟丙基壳聚糖和聚乙烯醇为原料,制备羟丙基壳聚糖-聚乙烯醇互穿网络水凝胶并研究其药物释放性能.考察羟丙基壳聚糖质量浓度、聚乙烯醇与羟丙基壳聚糖质量比、交联剂用量等因素对羟丙基壳聚糖-聚乙烯醇互穿网络水凝胶溶胀性能的影响;测定凝胶对温度和pH的敏感性;以利巴韦林为模型研究凝胶对药物的释放性能.结果表明:该水凝胶具有良好的溶胀性、温度及pH敏感性,对利巴韦林有一定的缓释作用,可望用于新型的药物载体.     

壳聚糖缓释微囊的研制及性能初探

应用悬浮交联法制备壳聚糖微胶囊,并研究不同反应条件对药物包封率、微囊溶胀度及释放性能的影响。结果表明,壳聚糖浓度在1.5%-3.0%范围内,随其浓度的增高,药物包封率增大,微囊溶胀度增大,在水中的动态释放速率降低;戊二醛的用量越多,药物包封率越大,溶胀度越小,在水中的释放率越小;药物/壳聚糖用量比增大,包封率降低,释放率增大,而微囊的溶胀度几乎不受影响。     

N-琥珀酰壳聚糖的合成及其物理化学的性能

利用壳聚糖和琥珀酸酐反应合成了N-琥珀酰壳聚糖,1H NMR分析表明通过反应可在壳聚糖的侧氨基引入亲水性的羧基,增加琥珀酸酐/氨基的摩尔投料比或者选择分子质量较小的壳聚糖,有利于提高N-琥珀酰壳聚糖的琥珀酰化度.等电点分析结果表明,壳聚糖分子质量越小,N-琥珀酰壳聚糖的等电点pI值越低.溶解度分析结果表明,N-琥珀酰壳聚糖的亲水性得到明显改善,在中性条件下表现出微弱的溶解性,但在酸性和碱性条件下均表现出良好的溶解性,此性质对其在生物医学和药物载体方面的应用具有重要的意义.     

氟苯尼考/壳聚糖纳米微球的制备及其缓释性能

以三聚磷酸钠为交联剂,采用离子交联法制备了氟苯尼考/壳聚糖纳米微球,用激光粒度分析仪、扫描电镜表征了该纳米微球的微观结构和形态,并通过Zeta电位和红外光谱分析该载药纳米微球的形成机理.结果显示:当氟苯尼考与壳聚糖的质量分数为3∶5、壳聚糖与三聚磷酸钠的质量分数为5∶1时,氟苯尼考/壳聚糖纳米微球对氟苯尼考有较大的包封率(64.5%)和载药量(44.0%),并具有较好的缓释性能(45.5 h内释放79.2%),作为氟苯尼考的缓释剂型是可行的.药物释放曲线符合一级动力学方程.     

生物纳米薄膜的制备及其AFM表征

生物纳米薄膜的制备与表征对功能性有机化合物的实用化起着非常重要的作用.本文主要介绍利用分子自组装、LB技术以及将旋涂技术与AFM针尖操控相结合的方法分别制备的黄原胶、硬脂酸和壳聚糖纳米生物薄膜及其AFM表征结果.AFM测试显示,黄原胶分子在分子间协同作用下可以形成具有网状结构薄膜,NaCl盐溶液浓度和浸泡时间等可以调控在硬脂酸LB膜上所蚀刻孔径的大小.同时,AFM形貌表征与其操控技术的联用,不仅得到了薄膜表面的实时形貌,而且制备出具有纳米级厚度的超薄壳聚糖纳米膜.这些研究不仅为生物纳米薄膜的制备与表征提供了新型的方法及思路,而且可以进一步推动纳米薄膜在多种领域内的发展与应用.     

过硫酸盐缓释材料研发及其对水中环丙沙星的氧化

为了在一定周期内连续稳定地释放氧化剂，采用环境友好的膨润土和聚乳酸作为原料，通过造粒结合包膜的方法制备了一种新型的过硫酸盐缓释材料(CRPM).研究表明：CRPM的释放规律符合零级动力学特征，表明该材料可稳定释放过硫酸盐.通过改变致孔剂NaCl含量、颗粒尺寸和包膜层数可以调控CRPM的释放速率.该材料的过硫酸盐释放半减期在4～1 613 d,可以满足不同污染修复周期的需求.通过Fe²⁺活化CRPM降解水中的环丙沙星(CIP),当CIP的浓度较低时，去除率相对较高.5次循环氧化CIP的去除率比较稳定，说明CRPM可以稳定地释放过硫酸盐.通过傅里叶变换衰减全反射红外光谱法和差示扫描量热法表征说明，在氧化过程中聚乳酸包膜层的化学结构和热稳定性并未发生显著变化，具有比较好的稳定性.     

热激活延迟荧光材料的光致发光研究

为了能够进一步理解分子结构和分子之间相互作用对热激活延迟荧光(Thermally activated delayed fluorescence,TADF)材料光物理过程的影响,该文研究了TADF材料2,4,5,6-四(9-咔唑基)-间苯二腈(2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene,4Cz IPN)和2,3,5,6-四(3,6-二苯基-9-咔唑基)-对苯二腈(2,3,5,6-tetrakis(3,6-diphenylcarbazol-9-yl)-1,4-dicyanobenzene,4Cz TPN-Ph)薄膜在不同温度下的发光光谱。发现对于4Cz IPN薄膜,在280 K附近,随着温度的增加,发光强度有反常增加的现象,该现象被归因于4Cz IPN分子之间的相互作用在该温度下变弱。同时,在分子结构稍有不同的4Cz TPN-Ph中,没有观察到类似现象。研究结果表明:分子结构可以用来调控薄膜中分子相互作用对发光过程的影响,从而进一步提高有机发光二极管的效率。     

用于食品保鲜包装的聚乳酸透气膜研究

制备了聚乳酸透气膜,并研究了其用于猪肉包装的保鲜效果.采用非溶剂致相分离法制备聚乳酸膜,通过添加N-甲基吡咯烷酮,使得薄膜具备多孔结构.对薄膜的透光率进行了测试,利用扫描电镜和红外光谱仪对薄膜的微观结构和基团组成进行了表征.实验发现,聚乳酸多孔膜扫描电镜图与聚乳酸纯膜相比,薄膜内部具有均匀的多孔结构.从红外光谱图中可以看出,添加了N-甲基吡咯烷酮的薄膜与聚乳酸纯膜的吸收峰没有明显的差别,说明N-甲基吡咯烷酮在后续操作中从薄膜中分离出来,形成孔洞后并不会影响聚乳酸膜本身结构.在薄膜用于新鲜猪肉的包装中,通过聚乳酸透气膜的包装,猪肉的保质期得到了延长.与保鲜袋、保鲜膜、聚乳酸纯膜包装的猪肉相比,聚乳酸透气膜能有效延长猪肉保质期2～3 d.     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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