Study on the Kink Angle of Multiwall Carbon Nanotubes

自从碳纳米管被发现以来，人们便一直关注这个纳米尺度管的特性。对纳米碳管特性的研究主要在电磁性能、力学性能、热学性能、光学性能、储氢特性和电化学性能等方面。由于碳纳米管具有以上的特性，人们开始探索在实际商业制品中如何应用它们。碳纳米管分为多壁碳纳米管和单壁碳纳米管。碳纳米管的结构多样，实验观察到十二边形的环状多壁碳纳米管，每次碳管弯曲的角度为30度。对碳管弯曲角度的研究，前人提出了两种模型，一种是五边形－七边形对模型，另一种是应用分子动力学模拟的方法。这两种模型仅限于解释单壁碳纳米管的弯曲。由于多壁碳纳米管各层并不具有同步性，因此这两个模型不能用来解释十二边形的环状碳管。本文将应用弹性理论，引进...Since carbon nanotubes was discovered, much attention has been paid to the characteristics of these nano scale tubes. Most of investigation on carbon nanotubes center on electromagnetic, mechanical, thermal, optical, hydrogen-enclosed and electrochemical properties and their potential applications. Carbon nanotubes are categorized into single-wall carbon nanotubes and multiwall carbon nanotub...学位：理学硕士院系专业：物理与机电工程学院物理学系_理论物理学号：20022400

Phase transition and wetting behavior of liquid crystal cell under magnetic field with the substrate coupling

液晶在界面的锚泊能量最早由Rapini和Papoular于1969提出以简单唯象公 式1/2Wsin2ϕ表示，在接下来很长一段时间这个公式作为基本的锚泊能被广泛应 用于液晶相关的研究中，但是后来人们发现这个公式只能用于方位角形变很小的情 况，当方位角的形变不能忽略时，RP公式表示的锚泊能与实验上得到的结果差异较 大，于是有人提出对RP公式进行修正，但是这些修正的公式都缺少理论上的证明， 一直到最近由Fukuda从理论上计算推到得到新的锚泊能公式，我们称之为Fukuda锚 泊能，这个锚泊能也得到了实验的证明。 本文研究的是厚度有限的液晶盒模型，液晶盒具有两个相同的界面，并...Anchoring energy of liquid crystals at substrates was first expressed phenomenologically by RP form and had been widely used in the liquid crystal study involving surface interaction for a long time, but later on the deviation of theoretical prediction given by RP from experimental results was found. Further studies showed that it is due to the azimuthal distortion, which can not be neglected. Som...学位：理学博士院系专业：物理与机电工程学院_理论物理学号：1982008015049

The Phase Transition of Nematic Liquid Crystal Cells Bounded by Surfactant-Laden Interfaces

National Science Foundation of China [50873083, 10974162]Taking into account the surface-coupling strength effect, we discuss the phase transitions of a finite thickness cell bounded by surfactant-laden interfaces in a magnetic field perpendicular to the substrate and it is compared with that of a semi-infinite system. It is found that the larger the thickness, the closer the three-dimensional phase transition surface of the finite system to that of the semi-infinite one. The simulation also shows that when a magnetic field is applied to a nematic semi-infinite sample, an orientational phase transition first takes place close to the interface and then extends to the inner space as the temperature increases

Screening,Fermentation Condition and Enzyme Characterization of Multicomponent Enzymes Producing Pseudomonas sp.NJ197

从南极普利兹湾深海沉积物中筛选到一株同时产多种冷适应酶的菌株NJ197,细菌学形态鉴定及16S rDNA序列分析表明,该菌株属于假单胞菌属(Pseudomonas).生长特性研究表明,该菌株属于耐冷菌,其最适生长温度为5~15℃.NJ197菌株能利用多种单一的碳、氮源产酶,最适产酶温度为20℃,最高产酶温度为30℃.粗酶液经硫酸铵盐析、DEAE cellulose-52柱层析初步分离纯化后进行酶学性质的研究.该菌株所分泌复合酶中脂肪酶和淀粉酶的活力最高,它们的最适作用温度分别为30℃和35℃,最适pH值分别为9.0和9.5,对热敏感,是典型的碱性冷适应复合酶.Ca2+、Mn2+、Cu2+、Co2+、Fe3+对该复合酶有较为明显的激活作用,而Zn2+、Hg2+、Rb2+、Cd2+、EDTA则能抑制酶活.其中脂肪酶能在高浓度的SDS、CHAPS等变性剂中表现出较好的稳定性.图5表2参21A strain NJ197, producing cold-adapted complex enzyme, was isolated fromdeep sea sediment of the Prydz Bay, Antarctic. The morphological identification and 16S rDNA sequence analysis showed that it belonged to genus Pseudomonas. The optimal growth temperature of the Pseudomonas sp. NJ197 was 5~15 ℃, indicating that it was a psychro- tolerant bacterium. The strain could use various single carbonaceous and nitrogenous substances to produce complex enzyme. Its optimal and highest temperatures for enzyme production were 20 ℃ and 30 ℃, respectively. The enzyme purification was performed by ammonium sulfate fractionation and anion exchange chromatography with DEAE cellulose-52. The activities of lipase and amylase were the strongest among the complex enzymes produced by Pseudomonas sp. NJ197, and the both were sensitive to high temperature. The optimal temperature and pH value for the lipase activity were 30 ℃ and 9.0, while those for the amylase activity were 35 ℃ and 9.5, respectively. The results indicated that they were typical alkaline cold-adapted enzymes, whose activities were stimulated by Ca~ 2+ , Mn~ 2+ , Cu~ 2+ , Co~ 2+ and Fe~ 3+ , and inhibited by Zn~ 2+ , Hg~ 2+ , Rb~ 2+ , Cd~ 2+ and EDTA. The cold-adapted lipase showed better resistance to inactivation of 1 detergents, such as SDS and CHAPS. Fig 5 , Tab 2, Ref 21国家自然科学青年基金(No.40406029)资助~

Screening and molecular identification of cold-active chitinase-producing bacteria from Antarctica

从南极普里兹湾深海底泥样品中分离得到一批嗜冷细菌,对这些嗜冷细菌进行了产几丁质酶菌株的筛选,对其中一株具有较高产酶活性的菌株AC167所分泌的几丁质酶进行了性质分析,并通过16S rDNA序列分析进行了菌株的分子鉴定。该菌株最适生长温度为10℃,最高生长温度为25℃,是典型的嗜冷菌,经16S rDNA序列比较及系统发育分析鉴定为假单胞菌属(Pseudomonas)。该菌株只在低于25℃的条件下分泌几丁质酶,酶的最适反应温度为30°C,属于低温酶。An amount of psychrophilic bacteria was isolated from deep sea sediment collected from Prydz Bay,Antarctica.The strain AC167,which showed high cold-active chitinase activity,was screened from these bacteria.It was identified as a Pseudomonas species by 16S rDNA sequence comparison.The optimal and highest temperatures for the growth of Pseudomonas strain AC167 were 10℃ and 25℃ respectively,indicating that it was a typical psychrophilic bacterium.The chitinase produced by Pseudomonas strain AC167 belonged to cold-active enzyme because it was most active at 30℃ and was secreted only at temperatures under 25℃.国家自然科学青年基金资助项目(4406029);; 国家海洋局青年基金资助项目(98310

Dynamics of a Magnetic Nanowire in Twisted Nematic Liquid Crystal

液晶中的纳米颗粒悬浮体系由于其独特的性质引起了极大的关注.采用保角变换法和等效电容法,对悬浮于扭曲型向列相液晶盒中的磁性纳米金属丝在外加恒定磁场下的动态响应行为进行了研究,并将理论计算结果与实验结果作比较.通过比较发现,理论计算结果与实验结果符合得很好.Systems of nanoparticles suspended in liquid crystal have raised great interest because of their unique property and the potential as novel materials.The dynamic behaviors of a nickel nanowire suspended in a twisted nematic liquid crystal cell under constant magnetic field are analyzed,using the methods of equivalent capacitance and conformal mapping.A comparison with experiments shows that our calculation agrees well with the experimental results.国家自然科学基金项目(50873083;10974162

微型流化床反应分析仪中煤半焦水蒸气气化反应特性

制备了在液氮中急速冷却和在氩气中自然冷却的两种半焦，采用扫描电镜（SEM）、N2吸附仪、红外光谱分析仪（FTIR）、X射线衍射仪（xRD）等方法系统比较了两种半焦的结构，并利用中国科学院过程工程研究所研发的微型流化床等温反应分析仪（MFBRA）研究包括动力学在内的水蒸气气化反应特性。研究发现：急速冷却半焦（Char-Q）具有更大的比表面积和更小的平均孔径，而自然冷却半焦（Char-S）的石墨化程度更高。在MFBRA中进行的气化反应结果揭示了Char-Q具有更快的反应速率。且比较通过等转化率法算出的活化能发现：Char-S水蒸气气化反应的活化能更大。利用MFBRA不仅求得了半焦水蒸气气化的总C转化的反应活化能（总体动力学），而且获得了生成各气体组分的反应（实际上为多个反应构成的体系）的活化能，实现了半焦水蒸气气化反应分析。因此，选择Char-Q作为分析试样更能反映真实热态半焦的气化行为，而MFBRA为深入研究涉及水蒸气参与的微分反应特性提供了有效的仪器与方法

微型流化床反应分析仪中煤半焦水蒸气气化反应特性

制备了在液氮中急速冷却和在氩气中自然冷却的两种半焦，采用扫描电镜（SEM）、N2吸附仪、红外光谱分析仪（FTIR）、X射线衍射仪（xRD）等方法系统比较了两种半焦的结构，并利用中国科学院过程工程研究所研发的微型流化床等温反应分析仪（MFBRA）研究包括动力学在内的水蒸气气化反应特性。研究发现：急速冷却半焦（Char-Q）具有更大的比表面积和更小的平均孔径，而自然冷却半焦（Char-S）的石墨化程度更高。在MFBRA中进行的气化反应结果揭示了Char-Q具有更快的反应速率。且比较通过等转化率法算出的活化能发现：Char-S水蒸气气化反应的活化能更大。利用MFBRA不仅求得了半焦水蒸气气化的总C转化的反应活化能（总体动力学），而且获得了生成各气体组分的反应（实际上为多个反应构成的体系）的活化能，实现了半焦水蒸气气化反应分析。因此，选择Char-Q作为分析试样更能反映真实热态半焦的气化行为，而MFBRA为深入研究涉及水蒸气参与的微分反应特性提供了有效的仪器与方法

licoo2电池正极三维微结构的montecarlo重构及特征化

对复合电极介观微结构采用实验以及数值方法进行重构是开发锂离子电池孔尺度模型的基础和前提。本文采用Monte Carlo方法重构了LiCoO_2电池正极的三维微结构, 重构单元的特征尺寸为纳米量级, 从而得到了明确区分活性材料、固体添加物以及孔相(电解液)的微结构, 随后对重构电极进行了特征化分析, 得到了微结构的连通性、比表面积等特征信息, 并采用D3Q15 LBM模型计算了重构电极的有效热导率、电解液(或固相)的有效传输系数, 电解液或固相的扭曲率。重建电极与实际电极的孔隙率、组分体积分数、相关函数等重要统计特性相一致。LB数值结果说明了有效传输参数与电极微构型的密切相关性