3D打印工艺参数对组织工程支架微观结构的影响研究

挤出式3D打印是制备组织工程支架的重要技术手段之一.一个性能良好的组织工程支架必须具备小孔隙、高孔隙率的内部微观结构.针对挤出式3D打印支架成形动态过程,建立了打印材料成形过程热-力耦合动力学模型,并通过数值模拟研究了主要打印工艺参数对支架成形的孔隙尺寸、材料重熔特性的影响.结果表明,支架的孔隙尺寸随打印时间间隔和材料粘度的增大而增大,但随基板温度的升高而降低;支架重熔度与孔隙尺寸变化趋势相反;其中材料粘度的变化对成形支架的孔隙尺寸和重熔度的影响最为明显.     

基于活塞挤出的组织工程支架低温沉积制造工艺

生物材料及其成形工艺对组织工程支架的性能有重要影响。快速成形(RP)工艺可实现个性化制造和可控的材料、结构组成,因此在组织工程中得到广泛应用。该文设计开发基于活塞挤出的材料喷头,对挤出工艺进行探讨与研究,提出采用压力自释放方案解决其流涎问题,并将其应用于低温沉积制造(LDM)工艺。实验表明,基于活塞挤出的LDM工艺可以成形组织工程支架,并且具有广泛的材料适应性,可成形多种生物材料,尤其可成形其他RP工艺难于成形的胶原材料。     

离心喷射沉积钛铝金属间化合物的研究进展

回顾了采用离心喷射沉积成形技术制备Ti- 48Al- 2Mn - 2Nb金属间化合物的基本特征、组织结构、力学性能等以及制备工艺和组织结构对TiAl基合金力学行为特征的影响的主要研究结果 .结果表明 ,通过离心喷射沉积成形技术制备的TiAl基合金达到目前国内外较先进的性能水平     

基于活塞挤出的组织工程支架低温沉积制造工艺

快速成形(RP)工艺可实现个性化制造和可控的材料、结构组成,因此在组织工程中得到广泛应用。该文设计开发基于活塞挤出的材料喷头,对挤出工艺进行探讨与研究,提出采用压力自释放方案解决其流涎问题,并将其应用于低温沉积制造(LDM)工艺。实验表明,基于活塞挤出的LDM工艺可以成形组织工程支架,并且具有广泛的材料适应性,可成形多种生物材料,尤其可成形其他RP工艺难于成形的胶原材料。     

PLLA/TCP复合骨组织载体框架的低温挤出成形

为制备骨组织工程的细胞与因子的三维载体框架,提出了聚左旋乳酸/磷酸三钙(PLLA/TCP)复合材料快速成形的低温挤出成形工艺,研究了此工艺制备骨组织载体框架的设备与工艺过程。分析了制备的载体框架的孔隙结构、孔隙率、力学性能,并通过犬桡骨20mm节段性缺损的修复实验分析了制备的载体框架的生物相容性、体内降解性能和骨传导性能。制备的载体框架具有良好的综合性能,可以作为骨组织再生修复的载体框架。     

选区激光熔化铜合金纳米力学性能实验研究

针对选区激光熔化铜合金成形微观力学性能,采用正交实验设计方法,研究了不同工艺参数(激光功率、扫描速度、扫描间距)对成形样件纳米压痕硬度的影响.通过方差分析,得出了不同工艺参数对其纳米硬度影响程度,从而为选区激光熔化成形工艺提高零件表面微观力学性能提供理论指导.     

骨组织工程聚左旋乳酸多孔框架快速成形研究

为制备用于骨组织工程的细胞载体框架结构 ,对快速成形技术制备聚左旋乳酸多孔框架结构的若干基础问题进行了研究。提出了聚左旋乳酸快速成形的精密挤出成形工艺 ,研究了此工艺制备多孔框架结构的设备与工艺过程 ,分析了制备的多孔框架结构应用于组织工程人工骨的可行性。制备的多孔框架结构具有合适的分子量、孔隙结构、孔隙率、机械强度和生物降解性能 ,可以用作骨组织工程的组织再生框架结构     

金属橡胶辊压成形工艺及力学性能关联分析

针对新型辊压和传统冲压两种成形工艺制备薄壁平板状金属橡胶的微观结构和力学性能差异性,利用ABAQUS软件对成形过程进行有限元仿真,预测了两种金属橡胶内部细观结构的变形特征,验证了金属橡胶力学性能与结构的关联性,并确定了辊压优选参数。试验结果表明,不同成形工艺过程影响金属橡胶内部螺旋丝的钩连和接触形式,辊压比冲压得到的试样的刚度明显更低,但对金属橡胶的宏观损耗因子影响并不大;辊压时采用多道次、小压下量可以提高金属橡胶的阻尼性能,辊压速度和进料方向对金属橡胶的力学性能影响不明显。本研究工作为辊压成形制备金属橡胶的工艺设计及工程化应用提供了参考价值。     

CPP/PLLA软骨组织工程支架复合材料降解性能研究

采用溶媒浇铸/粒子滤取技术与气体发泡相结合的方法制备出CPP/PLLA软骨组织工程支架复合材料,测试了该支架复合材料的物理力学性能和降解性能.研究结果表明,CPP/PLLA软骨组织工程支架复合材料具有适宜的孔隙率,良好的降解性能和物理力学性能,以及三维连通、微孔、网状微观结构.因此,该复合材料有望成为软骨组织工程支架材料之一.     

组织工程多孔管状支架的低温挤出成形

聚乙二醇/聚对苯二甲酸丁二醇酯(PEG/PBT)-1,4二氧六环溶液体系在温度低于20℃时可变成凝胶态。将数字挤压/喷射技术与热致相分离技术结合,提出了一种新型多孔管状支架成形技术——低温挤出成形技术。构建了基于该技术的成形平台,研究了成形温度对支架宏观形貌、孔隙率、力学性能等的影响。该技术成形的支架孔隙率最高可达95%,微孔尺寸分布为35~48μm,支架弹性模量为61.9~106 kPa。人类颌下腺细胞种植实验表明:支架具有良好的细胞亲和性,在涎腺组织工程中具有良好的应用前景。     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

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.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to