分子模拟探究EO-PO共聚物影响添加剂界面膜的机制

采用全原子分子动力学模拟方法研究破乳剂EO-PO (环氧乙烷-环氧丙烷共聚物)和二苯胺抗氧剂(DPA)、磷酸胺盐极压抗磨剂(PN)、硫化烯烃极压抗磨剂(S4)、金属缓蚀剂(T561)等润滑油添加剂在正辛烷/水体系的微观聚集行为，通过分析界面形态、密度分布、界面厚度、径向分布函数、氢键能等，探究EO-PO分子和各添加剂分子在油水界面的行为。结果表明：各添加剂分子均在油水界面形成对应的界面膜，使得油水混合乳状液相较于单一的油水体系更为稳定，表明各添加剂在作为功能添加剂的同时也起到了一定的乳化作用；EO-PO分子较添加剂分子具有更强的亲水性，可以在界面上顶替添加剂分子与水相互作用，从而达到破坏界面膜的稳定性，使得油相和水相完全分开的效果，因此对于油水乳化液，EO-PO分子具有很明显的破乳作用；在含有不同添加剂的各体系中，EO-PO分子与水有不同程度的相互作用，其中在含有PN和DPA分子的体系中，EO-PO分子对其界面膜破坏较大，破乳效果较佳。     

分子动力学模拟巴氏合金界面磁性液体润滑行为

磁性液体因其顺磁可控的流变特性,可满足极端工况对滑动轴承润滑油膜稳定性不断提高的要求,在轴承润滑方面具有良好的应用前景。为探究磁性液体微观润滑机制,采用分子动力学模拟方法构建和优化巴氏合金界面磁性液体润滑的微观模型,并根据实际工况进行限制性剪切模拟,研究温度和剪切速度对PAO6基磁性液体在巴氏合金界面润滑行为的影响;通过分析滑动过程中相对浓度分布、温度分布、速度分布、均方位移和界面吸附能等参数的变化,从分子层面揭示磁性液体微观润滑的作用机制。结果表明：PAO6基磁性液体具有良好的扩散性和散热性,可以粘附在巴氏合金摩擦界面起到很好的承载和减磨作用;在高温和高剪切速度下,磁性液体润滑膜仍呈现出良好的稳定性,磁性颗粒具有良好的扩散能力。研究结果有助于完善纳米薄膜润滑理论,对磁性液体的工程应用具有现实指导意义。     

SPC、SPC/E和TIP3P模型水的结构和性质

本文采用分子动力学方法分别计算了SPC、SPC/E和TIP3P水的密度、自扩散系数等热力学性质。通过对径向分布函数的分析发现,三种模型水的g(r)没有明显的差异,且温度越低,径向分布函数的峰值越大,说明水分子的结构越明显,分子间的氢键越强,分子极性也越大。     

汽轮机油乳化与破乳机制

研究抗磨汽轮机油中各种添加剂对体系连续相黏度和表界面性能的影响。结果表明,各种添加剂对连续相黏度没有明显影响;防锈剂大大降低了体系的界面张力,是引起体系乳化的主要原因;破乳剂显示出的表面活性更强,能进一步降低体系的界面张力,使体系的乳状液稳定性变差,发生破乳化;破乳剂降低界面张力的能力越强,其破乳化性能越好。     

惯性和滑移对弹性金属塑料轴承的影响研究

从连续性方程和Navier-Stokes方程出发,推导出在圆柱坐标系中考虑了界面滑移和流体惯性影响的雷诺方程。通过数值计算,考察了界面滑移和流体惯性对弹性金属塑料径向滑动轴承水膜压力和承载能力的影响程度。计算结果表明：界面滑移将降低水膜压力和承载能力,流体惯性力的存在略微增大了水膜压力和承载能力;随偏心率的增大,界面滑移对水膜压力和承载能力的影响程度增大。
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Cl-离子作用于镁表面的腐蚀特性研究

本文用微观方法研究了Cl~-离子作用于镁表面的腐蚀特性,建立了反应模型,用微观的方法研究了Cl~-离子的加入镁表面的均方分布函数和镁原子和氧原子之间的径向分布函数。结果表明:随着Cl~-离子的加入,会破坏水分子的稳定结构,加快了镁表面与水中的氧原子的反应,从而使镁表面的腐蚀速率不断增大。     

电子封装中超声波线焊机理的分子动力学模拟研究

通过对超声波线焊中的界面接触,以及拉脱实验中的界面分离现象进行分子动力学模拟,从微观角度探讨了超声波线焊的机理。由于实际焊接区域处于平面应变的受力状态,模拟时建立两维的原子模型,采用Sutton-Chen势能函数描述金原子之间的相互作用。模拟结果表明,超声波线焊时由于金线与焊盘之间的紧密接触,产生强大的原子间作用力,从而导致牢固的界面键合,这是超声波线焊的微观机理。将有限元分析和分子动力学模拟相结合,可以计算超声波线焊的界面焊接强度,其结果与拉脱实验相符合。     

推进剂界面脱黏的有限元分析

采用黏结界面单元对推进剂的界面脱黏过程进行模拟,通过分析发现,由于推进剂内各组分的材料属性不同,受载条件下推进剂的应力应变分布很不均匀,基体变形大,颗粒变形小。推进剂黏结界面颗粒大小、取向以及相互之间的靠近程度对应力应变分布的影响较大,粒径越大,对应力应变分布的影响越大。应力集中首先出现在大颗粒周围,随着载荷的增加,大颗粒对应力应变分布的影响增大;并且界面脱黏位置受颗粒之间的影响较大,颗粒之间的相互作用影响了推进剂中微观损伤的演化,大颗粒之间的相互影响较大。     

舰船用水润滑轴承微观界面润滑机理研究

针对水润滑轴承微观界面润滑状态和润滑机理存在的不清楚、不明朗等问题,开展微凹痕对轴承微观界面润滑机理影响的研究。在建立单一微凹痕内部流体动力学模型的基础上,研究微凹痕内部涡流结构变化特性,分析微凹痕内部流场动力学特征,讨论形貌特征参数与润滑性能的变化规律,证明流体动力学特性随表面形貌的演化规律,验证微凹痕对轴承微观界面润滑机理的影响规律,从而提出微尺度下水润滑轴承润滑理论,并从微观层面探究粗糙峰与轴承润滑状态转变之间的关系,进而提出判断润滑状态转变的微观尺度标准。结果表明,微动压效应、微空化效应、微惯性效应三者共同构成水润滑轴承微观界面的润滑机理,大量微凹痕累积进而可以增强轴承承载能力、降低摩擦功耗。     

自适应参数驱动的装配界面形状主动设计方法

应力分布均匀程度是衡量精密机电产品装配精度和性能稳定性的重要指标,均匀的应力分布也是当前精密机电产品装配过程所追求的目标之一。形状设计是改善装配界面接触应力分布的重要途径,针对当前基于应力分布的装配界面形状主动设计方法中初始参数取值难以确定,且相关参数对优化过程计算效率、数值计算稳定性影响较大的问题,提出了一种根据优化过程中接触应力分布均匀程度变化信息来调节优化参数的自适应参数计算方法。并以典型单螺栓连接结构为设计对象,对比了采用自适应参数设计方法与采用固定参数设计方法分别进行装配界面形状主动设计后的结果。理论分析结果表明：该方法可以很好地解决基于应力分布的装配界面形状主动设计方法中初始参数难以确定的问题,同时提高了优化效果、计算效率和优化过程中的数值计算稳定性。     

Virus present in the reproductive tract of asymptomatic drones of honey bee (Apis mellifera l.), and possible infection of queen during mating

Virus particles and viral inclusions were detected by transmission electron microscopy examination of sections of the seminal vesicles and mucus gland of asymptomatic young drones from colonies of Apis mellifera lightly infested by Varroa mite. In the mucus gland the infection was found in the muscular sheath and epithelium, while in the seminal vesicle in cells of the outer serosa. Isolated viral particles were also observed in the hemolymph occupying the intercellular spaces of the muscular sheath fibers. In the muscle the virus appeared as polygonal crystalloid inclusions, while in the epithelium mainly inside cytoplasmic vesicles. The infected cells apparently are not damaged. The virus particles are present in the hemolymph and forming more mature structures, as crystalloids, in the muscle. This suggests that the virus is liberated in the body fluid and infects the tissues penetrating the cells through endocytosis. The presence of virus in mucus gland epithelial vesicles raise the possibility of its transference to the gland secretion and therefore, to the semen.     

Ultrastructure of Tracheal Surface Liquid: Low-Temperature Scanning Electron Microscopy

A layer of liquid lines the airways in the lung. Previous microscopic studies have suggested that it is in two phases, with a mucous gel lying above a periciliary sol. However, shrinkage artifacts due to chemical fixation, dehydration, and drying have prevented reliable estimates of the depth of these layers. To avoid such problems, we have studied the surface liquid of bovine trachea by low-temperature scanning electron microscopy (LTSEM). A polished copper probe cooled to liquid nitrogen temperature was applied to the mucosal surface of sheets of excised tracheal epithelium to effect rapid freezing of surface liquid. Tissue sheets were then mounted in an LTSEM (AMRay 1000A with Biochamber) which maintains samples at -180°C with a Joule-Thompson refrigerator built into the stage. Tissues were fractured at right angles to the epithelial surface, coated with gold, and viewed, all at 10^?5 to 10^?6 torr without transfer through air. The sample was stable under the electron beam at accelerating voltages up to 20 kV. Epithelial features (nuclei, cilia, microvilli, mucous granules) were well preserved. The mucosal surface of the cells was covered with material on the order of 8 μm in depth. The mucous gel and periciliary sol could be seen as distinct layers and could be distinguished by the size and pattern of ice crystal voids generated by radiant-etching of the fractured surface of the sample.     

Scanning electron microscopic and histological studies of the buccal cavity of a phytoplanktivorous small freshwater fish,Amblypharyngodon mola

The electron microscopic and histological studies of the buccal‐cavity of herbivorous fish Mola (Amblypharyngodon mola) were performed. The studies revealed that the architectures of the buccal cavity of A. mola support the herbivory nature of the fish. Both the upper and lower jaws of the fish are rich in mucus glands, unculi, and microridges. The presence of papillae like taste buds in the lower jaw of A. mola indicates the mechanosensory role of the lower jaw during gustation. These features directly support a gustatory feeding behavior associated with filter feeding in this small freshwater fish.     

GPIB接口控制器的研究

介绍了基于TNT4882的GPIB接口控制器的设计方案,阐述了GPIB接口规范及其接口专用芯片TNT4882的功能,给出了GPIB接口电路及其软件控制流程.该GPIB接口控制电路可移植性强,为仪器仪表的远程控制和资源共享提供了有力的媒介.     

Toward an optimized strategy of using various airway mucus clearance techniques to treat critically ill COVID-19 patients

Coronavirus disease 2019 (COVID-19) caused by acute respiratory syndrome coronavirus 2 (SARS-Cov-2) is still threatening the human life and society throughout the world. For those critically ill patients, mechanical ventilation (MV) is essential to provide life support during treatment. However, both the virus infection and MV disrupt the balance between secretion and elimination of airway mucus and lead to mucus accumulation in the lung. Postmortem examination verified that the lungs in patients died of COVID-19 are indeed filled with sticky mucus, suggesting a great need to improve airway mucus clearance in critically ill COVID-19 patients. Therefore, it may be helpful to comprehensively review the current understanding regarding the changes of biochemical and rheological features of airway mucus associated with the disease, as well as the physiological principles and algorithm to decide airway clearance techniques suitable for the critically ill COVID-19 patients. Based on these considerations, optimized strategies may be developed to eliminate the airway mucus accumulated in the airways of critically ill COVID-19 patients.     

新一代战斗机显控界面布局设计研究

随着科学技术的进步,飞行员与战斗机的交互也越来越复杂,其生理负荷和心理负担在某些情况下已经超过了飞行员生理和心理的限度,对战斗机和飞行员的安全产生了诸多不确定因素。文中以大屏幕显控界面为设计环境,针对现代复杂的战斗机交互界面问题归纳总结了战斗机驾驶舱显控界面适用的设计准则,以生态界面理论为依据抽象分析战斗机显控系统层级...     

Occurrence, distribution, and localisation of metals in cnidarians

The Cnidaria are simple organisms that have remarkable physiological features susceptible to microscopic investigation. As a group they produce cnidae, the most complex intracellular organelles known, form symbioses with a range of unicellular algae, contain mucocytes that account for a very substantial fraction of their body mass, and form complex skeletal structures of calcium carbonate. This review summarises contributions dealing with the distribution and localisation of metals of physiological and pathological importance within soft tissues and skeletons. Whilst there have been detailed studies of microscale metal distribution, using X-ray microanalysis, in the stinging organelles or cnidocysts and in mucocytes, other cells such as symbiotic algae and the epithelial cells have received little attention. In the skeleton-producing scleractinian corals X-ray microanalysis has provided tenuous, but persistent, evidence of Ca associated with intracellular vesicles or granules in the skeletogenic epithelium, even though the investigations were technically limited. These observations may be germane to the intriguing and intransigent problem of the mechanism of coral calcification. Metal localisation in coral skeleton at the resolution of annual growth rings has been concerned with the validity of Sr/Ca and Mg/Ca ratios as thermometers for paleoclimatic studies. It is not clear whether these ratios are influenced primarily by environmental or biological parameters. Microscale analyses by X-ray microanalysis and ion microprobe indicate a much greater variability of metal ratios which suggests biological control of metal deposition. New data are provided on the elemental composition, measured by X-ray microanalysis, of cells and cell compartments in the coral Galaxea fascicularis and zooxanthellae in the anemone Aiptasia sp. New information is also presented on changing Ca/Sr ratios at the skeletal interface in Galaxea fascicularis.     

不同螺纹下微型机器人的无损伤驱动方法

研究一种利用螺旋旋转产生牵引力的微型机器人驱动机构。详细分析计算了微型机器人在采用矩形和梯形圆柱螺旋时的轴向摩擦牵引力和最小粘液膜厚度。通过对比两种螺纹下微型机器人的运动特性参数，得到了微型机器人的优化结构参数。     

MATLAB＋FPGA的红外图像处理与接收

本设计作为红外模拟靶标系统的一部分。主要实现基于MAT-LAB红外图像的读取与灰度值转化。并将图像灰度值通过串口发送给FPGA控制系统,对数据传输速率要求不高,传输距离也不要求很长。但传输数据要求准确可靠。     

电站冷凝器用钛钢复合板结合界面均匀性研究

采用高低爆速炸药分段式铺药的方式对钛/钢复合管板进行爆炸焊接.对爆炸复合法制备的电站冷凝器用29 m2、材料为Gr.2/Gr.70的管板结合界面的微观组织和力学性能进行了分析,结果表明,采用2250～2300 m/s的高低爆速和分段布药工艺制备的大面积钛/钢复合板,在无损检测时无杂波,结合界面均匀,力学性能符合ASTM...