仿生增强制备聚乳酸基骨组织工程复合材料

依据仿生原理制备了纳米羟基磷灰石聚乳酸(nHA-PLA)复合的骨框架材料.此复合材料中的主要成分是纳米羟基磷灰石,纳米相的羟基磷灰石就是天然骨中主要的无机相.在保持高孔隙率(90%)的同时,复合材料的抗压性能达到2.07 MPa,高于单纯的聚乳酸框架材料(为0.89 MPa).分离成骨细胞并在三维框架材料上培养,用扫描电镜进行观察,复合材料具有很好的细胞贴附性能.仿生制备的三维纳米羟基磷灰石聚乳酸复合骨框架材料,无论从结构还是性能上,都是骨组织工程中的优选材料之一.     

基于图像相关法的珊瑚羟基磷灰石材料静态力学性能

通过实验证明引伸计不适于测量珊瑚羟基磷灰骨替代石材料的力学性质之后,采用高分辨率数字图像相关法测量材料的力学性质,得到了珊瑚羟基磷灰石完整的应力-应变曲线;测得弹性模量为(10.91±0.88)GPa,泊松比为0.244±0.025,压缩极限应力为(14.04±2.01)MPa.测试结果表明,珊瑚羟基磷灰骨替代石材料的应力-应变曲线在断裂前呈良好的线性关系.最后讨论了珊瑚羟基磷灰石与骨的力学相容性.     

纳米羟基磷灰石/聚酰胺复合材料的制备及在骨修复中的应用研究

为总结近几年来有关纳米羟基磷灰石/聚酰胺复合物的制备方法以及在骨修复研究上的应用.以纳米羟基磷灰石/聚酰胺为关键词,从各类期刊数据库中检索有关纳米羟基磷灰石/聚合物的制备方法和应用的文献,总共查阅得到文献80篇.结果显示:纳米羟基磷灰石/聚酰胺复合物的制备方法主要有三种,均能制备出生物相容性良好的高韧性复合物,并且纳米羟基磷灰石/聚酰胺复合物在骨修复技术上得到了广泛应用.论述了纳米羟基磷灰石/聚酰胺复合材料的制备方法,以及该复合材料的生物相容性研究和在骨修复临床中的应用进展.     

细菌纤维素组织工程支架的仿生矿化研究

骨骼创伤已经成为当今影响人类健康的一大病症。因此,骨修复材料就成为研究的一大热点。骨组织工程支架作为重要的骨修复材料,可以诱导成骨细胞生长并为新骨生长提供条件。传统的骨组织工程支架包括合成高分子(如聚乳酸、聚乙醇酸等)和天然高分子(如胶原、壳聚糖等)。与传统支架材料相比,细菌纤维素(BC)具有良好的生物相容性、精细的纳米空间三维网络结构,有作为组织工程支架的潜能。通过仿生矿化处理,BC纳米纤维表面可以生长出羟基磷灰石(HA)的晶体颗粒,且HA颗粒均匀覆盖在纳米纤维表面。通过热分析得出,仿生矿化处理会使BC的热稳定性得到一定的提升。     

羟基磷灰石生物陶瓷材料的现状及展望

羟基磷灰石具有生物相容性和生物活性,是较好的生物陶瓷材料,被广泛应用于骨组织的修复与替代技术,现已形成多种制备羟基磷灰石粉末、块体材料及多孔材料的方法。但是,由于材料本身力学性能较差制约了羟基磷灰石的进一步应用,因此提高及制备综合性能优越的生物陶瓷复合材料是当今研究的重心和热点。     

纳米羟基磷灰石对骨相关细胞生物安全性的研究进展

总结近年来国内外纳米羟基磷灰石对于骨相关细胞生物安关于其全性方面的研究概况,包括了纳米羟基磷灰石对骨形成及成骨相关细胞活性的影响2方面。介绍了纳米羟基磷灰石对成骨细胞及基质细胞成骨分化的影响以及在体内骨形成作用及机制,同时总结了纳米羟基磷灰石通过不同浓度、尺寸对细胞活性的影响以及其通过活性氧线粒体途径、溶酶体途径对细胞活性影响的研究进展,并指出该领域尚待解决的问题为纳米羟基磷灰石早日应用于临床骨组织工程领域提供可靠参考.     

羟基磷灰石植入皮下组织不同阶段弹性模量的变化

人造骨替代材料-羟基磷灰石植入体内,随着骨组织和胶原纤维在其孔隙内的生长以及羟基磷灰石的降解,羟基磷灰石的整体弹性模量会逐渐变化.为了确定其植入体内后软组织对弹性模量的影响,将羟基磷灰石试样植入大白鼠的皮下,分别植入20、40、60和80,d时将其取出,采用数字图像相关方法研究纤维组织对人造羟基磷灰石的弹性模量的影响.研究结果显示,羟基磷灰石植入大白鼠皮下20,d时的弹性模量有明显增加,增加幅度为28.83%,之后弹性模量变化幅度变小.分析认为,最初的组织纤维附着在羟基磷灰石的微孔中,起到了增强的作用,之后软组织表面再生长的软组织增强作用会逐渐减弱.     

钛基/涂层型羟基磷灰石功能梯度生物材料研究进展

钛及钛合金是常用的医用生物材料,虽具有良好的生物相容性,但缺乏骨诱导能力,而羟基磷灰石(HA)有良好的生物活性能诱导骨生长,钛基/涂层型HA功能梯度生物材料(FGM)为解决二者的结合提供了新的思路.钛基/涂层型HA FGM其设计主要分为组成成分的梯度设计与孔隙梯度变化2种,通过基体与涂层表面之间形成逐渐过渡的功能梯度,能显著提高材料的机械强度和生物骨诱导能力.概述其设计、制备及性能评价等最新研究,为临床运用提供参考.     

羟基磷灰石基生物材料培养破骨细胞研究现状

骨重建是新骨组织替换旧骨或受损骨的生理过程,在无瘢痕骨愈合和受损骨再生中起着必要的作用。骨重建主要是骨形成细胞如成骨细胞（osteoblast,OB）,骨吸收细胞如破骨细胞（osteoclast,OC）,和巨噬细胞（macrophage,MP）等细胞之间的相互协调活动。OC作为生物体内唯一多核细胞,负责生物体内骨质的脱钙与骨基质的吸收。自然骨具有一定硬度、韧性,良好的生物活性,保证骨重建中细胞的增殖、分化、骨形成或骨再吸收等活性。以羟基磷灰石（hydroxyapatite,HA）为主的磷酸钙（HA-CaPs）是自然骨中矿物质的主要成分,具有优异的生物性能而被广泛应用于骨组织修复领域。总结了HA-CaPs物相成分、表面形貌等对OC等骨吸收细胞增殖、分化和骨吸收活性的影响,并通过OC对于骨修复材料体内吸收机制及细胞活性调控机制等探讨HA-CaPs与细胞间相互关系,以期为磷酸钙人工骨替代材料更加广泛的生物应用作理论参考。     

磷酸钙生物陶瓷涂层制备及其研究进展

羟基磷灰石是哺乳动物体内硬组织的主要无机成分 ,人工合成的羟基磷灰石具有优良的生物相容性和生物活性 但是纯的羟基磷灰石脆性大 ,强度较低 钛及钛合金等医用金属材料具有较好的强度、韧性和优良的加工性能 ,但是生物相容性差 金属基体羟基磷灰石涂层材料兼备金属材料优良的力学性能和生物陶瓷材料的生物特性 ,备受材料领域和医学领域学者的关注 涂层与基体的界面结合强度及涂层材料植入后的稳定性 ,是目前研究的热点和难点 简要评述了羟基磷灰石涂层的制备技术 ,介绍了近年来的研究进展 ,对提高结合强度和植入稳定性的方法进行了归纳     

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