原子尺度摩擦行为的分子动力学模拟

应用大规模分子动力学方法,模拟了具有原子级光滑和原子级粗糙形貌的刚性球形探头与弹性平面基体的干摩擦行为,研究了无/有粘附条件下的载荷与摩擦力、载荷与真实接触面积,以及摩擦力与真实接触面积之间的关系,对纳米尺度下的摩擦行为规律进行了分析.几种系统的真实接触面积-载荷关系都与相应的连续力学接触模型定性的一致,它们分别是Hertz光滑表面接触模型、Greenwood-Williamson粗糙表面接触模型和Mau-gis Dugdale粘着接触模型.无论是由光滑表面还是粗糙表面构成的摩擦系统,在无粘附条件下摩擦力与载荷成正比,而摩擦力与真实接触面积之间没有一个简单的关系;在粘附条件下摩擦力与真实接触面积成正比,而摩擦力与载荷之间表现为Maugis Dugdale模型预测的亚线性关系.研究表明,当表面作用从无粘附到粘附时,控制摩擦力的决定因素从载荷转变为接触面积,摩擦行为从载荷控制摩擦转变为粘着控制摩擦.     

“聚龙一号”装置上磁驱动铝飞片实验的数值模拟

采用二维磁驱动数值模拟程序MDSC2,对大电流脉冲装置聚龙一号上的151发次磁驱动370 m厚铝飞片实验、164发次磁驱动330 m厚铝飞片实验进行了数值模拟和分析。数值模拟表明：370 m厚铝飞片和330 m厚铝飞片的磁驱动过程中, VISAR测量的速度不是飞片自由面的速度,而是飞片中邻近自由面最近的固体反射面的速度。这是由于磁驱动飞片发射过程中,飞片自由面部分被烧蚀,密度低于固体密度状态,而飞片自由面和加载面中间的飞片还保持固体密度状态。VISAR测量的激光将穿过自由面的低于固体密度状态的飞片部分,到达飞片自由面最近的固体密度位置再反射回去,获得这一位置的飞片速度。数值模拟的飞片固体反射面速度历史和VISAR测量的速度历史相吻合。     

X箍缩三维数值模拟

利用FOI-PERFECT程序对X箍缩进行了3D数值模拟研究,给出了X箍缩的物理图像和动力学过程,探讨了Z箍缩中出现磁重联的可能性,并指出如果双丝Z箍缩中能够出现磁重联,那么X箍缩是更有利于磁重联出现的位形,并且,X箍缩中出现多重X射线暴的一个可能原因是z轴上多个位置出现磁重联。     

Theoretical Investigating Mechanisms of Drug-Resistance Generated by Mutation-Induced Changes in Influenza Viruses

Influenza A (A/H\begin{document}$ x $\end{document}N\begin{document}$ y $\end{document}) is a significant public health concern due to its high infectiousness and mortality. Neuraminidase, which interacts with sialic acid (SIA) in host cells, has become an essential target since its highly conserved catalytic center structure, while resistance mutations have already generated. Here, a detailed investigation of the drug resistance mechanism caused by mutations was performed for subtype N9 (A/H7N9). Molecular dynamics simulation and alanine-scanning-interaction-entropy method (ASIE) were used to explore the critical differences between N9 and Zanamivir (ZMR) before and after R294K mutation. The results showed that the mutation caused the hydrogen bond between Arg294 and ZMR to break, then the hydrogen bonding network was disrupted, leading to weakened binding ability and resistance. While in wild type (A/H7N9\begin{document}$ ^{ \rm{WT}} $\end{document}), this hydrogen bond was initially stable. Meanwhile, N9 derived from A/H11N9 was obtained as an R292K mutation. Then the relative binding free energy of N9 with five inhibitors (SIA, DAN, ZMR, G28, and G39) was predicted, basically consistent with experimental values, indicating that the calculated results were reliable by ASIE. In addition, Arg292 and Tyr406 were hot spots in the A/H11N9\begin{document}$ ^{ \rm{WT}} $\end{document}-drugs. However, Lys292 was not observed as a favorable contributing residue in A/H11N9\begin{document}$ ^{ \rm{R292K}} $\end{document}, which may promote resistance. In comparison, Tyr406 remained the hotspot feature when SIA, ZMR, and G28 binding to A/H11N9\begin{document}$ ^{ \rm{R292K}} $\end{document}. Combining the two groups, we speculate that the resistance was mainly caused by the disruption of the hydrogen bonding network and the transformation of hotspots. This study could guide novel drug delivery of drug-resistant mutations in the treatment of A/H\begin{document}$ x $\end{document}N9.     

气相色谱与串联质谱联用检测血清中脱氢表雄酮

在晚期前列腺癌雄激素全阻断治疗最终导致前列腺癌雄激素非依赖性的转变过程中,肾上腺分泌脱氢表雄酮(DHEA)被认为是重要的诱因。本研究主要利用睾丸摘除(去势)大鼠模型,对血清中DHEA浓度进行测定。采用了气相色谱与串联质谱联用(GC-MS/MS)技术,建立了高灵敏度的测定大鼠血清中脱氢表雄酮(DHEA)的方法。样品经过甲醇沉蛋白,而后固相萃取提取血清中微量的DHEA,通过七氟丁酸酐(HF-BA)衍生,采用GC-MS/MS测定。对固相萃取条件、衍生化条件以及质谱测定条件进行优化。DHEA在0.1~100μg/L范围内线性良好,相关系数r为0.9996;在2~50μg/L浓度范围内,加标回收率在99%~106%之间;相对标准偏差小于5%。本方法灵敏度高,选择性好,可满足临床对于血清样品中DHEA的测定要求。对去势大鼠血清中DHEA测定结果表明,去势后DHEA明显上升。     

基于地震波形分类的三角洲储层刻画与应用——以西湖凹陷J气田为例

西湖凹陷J气田是东海主要产量贡献的油气田之一,随着开发生产的深入,主力气井E开始见水,逐渐停产,对气田油气产量带来了较大影响,急需对储层展布范围及水体能量进行分析。以精细岩心观察描述为基础,根据岩石类型、沉积构造、沉积旋回及测录井资料,对研究区内平湖组沉积环境及相类型进行了分析,在此基础上对研究区主力层P7开展了基于地震波形分类的精细地震解释,识别并统计了3类地震波形分类标志,通过地震正演技术,初步验证了解释成果的可靠性;结合现代沉积模式,对P7层储层平面展布进行了刻画。研究表明：研究区主要发育3个三角洲朵叶体,据此计算P7气藏的水体倍数约20倍,主要来水方向为北偏东方向,更新后的油藏数值拟合效果较好,对研究区出水井治理及挖潜具有重要指导意义。     

醋酸调质钙基吸收剂的循环碳酸化特性

提出了采用醋酸溶液调质石灰石和白云石的方法来提高它们在循环煅烧-碳酸化过反应过程中吸收CO2的能力.在不同反应条件下分别研究了石灰石和白云石的醋酸化产物醋酸钙和醋酸钙镁在循环煅烧-碳酸化过程中的碳酸化转化率.结果表明:碳酸化温度在600～700℃时,醋酸钙和醋酸钙镁的转化率分别明显高于石灰石和白云石,经过15次循环和20次循环后其碳酸化转化率分别可达0.54和0.6.当煅烧温度从920℃增加到1 050℃时,醋酸钙和醋酸钙镁转化率和抗烧结性能明显优于石灰石和白云石.随着碳酸化气氛中CO2浓度的增加,醋酸钙和醋酸钙镁转化率的增量小于石灰石和白云石.存在最佳的粒径范围使醋酸钙和醋酸钙镁的碳酸化能力最大.虽然醋酸钙镁的碳酸化转化率高于醋酸钙,但单位质量煅烧后的醋酸钙的CO2吸收量大于醋酸钙镁.     

氟喹诺酮类化合物及其衍生物构效关系研究

利用分和学ＭＭＰＭ和量子化学ＣＮＤＯ／２方法对一系列氟喹诺酮类化合物分子进行计算,并由所计算的微观参数结合宏观疏水参数与活性指标进行多元逐步回归处理,建立了相关性很好的Ｈａｎｓｃｈ回归方程,根据回归方程,对影响抑菌活性的主要因素作了讨论。     

凸曲面平头立铣刀刀位轨迹的计算方法

采用球面刀在三坐标数控机床上加工具有凸曲面工位的零部件时，往往会导致几何形状误差，对此，运用点涉法原理，推导出在凸曲面上确定平头立铣刀五轴和三轴数控联动加工刀位轨迹的计算方法。     

Structure Refinement of the Icosahedral AIPdMn Quasicrystal Using Quantitative CBED

The atomic structure of the pcrfect AIPdMn icosahedral phase has been studied on a single crystal specimen by quantitative convergent beam electron diffraction (QCBED) technique in combination with describing the shape of atomic surface by symmetry adapted series of surface harmonics. The spherical model was used as the starting model for the refinement. By fitting the calculated electron diffraction intensities to the experimental line scan profile, the coefficients in the surface harmonics expansion of the boundaries of atomic surface are refined. The refined parameters show that the fluctuations of the external boundary of atomic surface for Pd at n0 can be as large as 0.2 nm. The boundaries of atomic surfaces for Mn show little fluctuation. In the present model. the number of unphysically short interatomic distances is significantly reduced in comparison with the spherical model.