繁殖期雌雄同体虾夷扇贝生殖腺组织学观察

历时3年,采用Bouin's液固定和常规组织切片技术,对照雌性和雄性生殖腺组织结构,研究了繁殖期雌雄同体生殖腺组织的结构特点及形成原因.结果显示:虾夷扇贝雌雄同体的存在与海区养殖环境有关,山东烟台养殖海区的雌雄同体比例高达19.2％.雌雄同体两性生殖腺滤泡发育不同步且间隔不分明,2-3月份部分雌性生殖腺中出现迅速增殖的雄性生殖细胞或滤泡,成为雌性为主的雌雄同体;4月份随着雌雄生殖腺滤泡的共同生长和部分排放,形成以雄性生殖腺为主或雌雄相间的雌雄同体.雌性转化为雄性是主要性逆转方向,229只虾夷扇贝中仅1例推测为雄性向雌性逆转,有些个体存在雌雄两种生殖细胞同时成熟和排放的现象,是否存在两种性别均衡发育有待进一步研究.     

阴道毛滴虫细胞结构、细胞化学与功能关系的电镜研究

阴道毛滴虫的电镜细胞化学反应显示有丰富内质网、发达高尔基体与完善溶酶体系统,缺乏线粒体,但有功能近似氢化酶体,它们分别与合成和加工水解酶等、消化被吞噬物及提供能量需要相适应。虫体粘附、吞噬与消化男女性生殖泌尿道上细胞和精子的超微结构观察表明,其多形性伪足、细胞衣、细胞骨架和溶酶体在此过程中起重要作用;吞噬方式有蚕食与吞食二种。探讨虫体超微结构水平致病机制,认为释放溶酶体水解酶与吞噬作用及伪足机械作用等直接因素,可损伤生殖泌尿器官上皮细胞;重症患者最终可能导致不育(孕)症。药物作用机制的电镜观察表明,洁尔阴最初破坏细胞膜,而替硝唑抑制蛋白质合成及细胞分裂,提示两药配合杀虫将高效、快速。     

细胞冻融策略优化及设备研究进展

低温冷冻保存是细胞治疗、辅助生殖等生物医学应用的使能技术之一.冷冻和复苏过程中,胞内外冰晶的形成和生长会对细胞产生损伤;其中,升降温速率又与冰晶的形成、生长有密切关系.本文在阐述程序化慢速冷冻和玻璃化快速冷冻两种细胞冻存方式及冷冻损伤两因素假说的基础上,对细胞特性、细胞外环境和升降温策略三个影响细胞冻存效果的要素进行分...     

液相和AlN-多型体对α-Sialon形貌的影响

本文通过SEM等手段研究了热压条件下不同液相量(＜12.5wt%)和AlN-多型体(＜10wt%)对α-Sialon形貌的影响.结果表明,液相量增加可以促使α-Sialon晶粒在一定程度上发育成长颗粒.AlN-多型体的添加使α-Sialon更容易按照其本征特性发育成具有较大长径比的细颗粒.α-Sialon晶粒的生长主要由界面反应控制,但组份对原料的溶解和扩散速率的影响也会影响到α-Sialon的结晶动力学,从而形成其不同的晶粒形貌.     

单增李斯特菌生态行为模型构建及机制研究进展

目的 探究食品中的单增李斯特菌随食品链相关条件的变化而发生的"生长-失活-再生长"生态行为规律.方法 以热加工为失活条件,综述单增李斯特菌生态行为的影响因素、模型构建和相关机制.结果 单增李斯特菌在"生长-失活"过程中,细胞的历史生长条件会对其失活特性产生影响,在"失活-再生长"过程中,细胞的历史生理状态会影响其修复再生长的延滞期.结论 食品链中细菌的生长和失活是连续的过程,有必要研究在连续的环境条件变化过程中细胞的生态行为,以期为食品风险评估和食品安全防控提供支持.     

再生强化技术在重油催化裂化装置中的应用

为了提高催化裂化再生器再生效率,减少助燃剂的用量,提出在催化裂化再生器内设置中国石油大学(北京)开发的Crosser格栅。Crosser格栅上有多个平行流道,每个流道设置一系列倾斜的导流叶片,相邻流道导流叶片的倾角相反。通过格栅对再生器内气泡的破碎,来减小气泡相和乳化相之间的传质阻力,同时抑制催化裂颗粒的轴向返混,进而提高再生器的再生效率。在一套年处理量为220万t的大型催化裂化再生器考察了Crosser格栅对其再生效果的影响。应用效果表明,在同等再生负荷下,格栅的使用强化了再生效果:催化剂的含碳量由0. 103%(质量分数)下降至0. 059%以下;稀密相温差由28. 6℃降低到17. 6℃;助燃剂用量减少了32. 9%;稀密相温度的径向方差减少约50%。     

SiC纤维表面C涂层的制备及介电性能研究

采用化学气相沉积(CVD)法,在SiC纤维表面沉积了100nm厚的C涂层,研究了制备温度对C涂层微观结构、单丝纤维体电导率及纤维编制体介电性能的影响.采用SEM和RAM显微技术(Raman microscopy)对C涂层的表面形貌和微观结构进行分析.结果表明:保持C涂层厚度一致,当沉积温度由800℃升到900℃后,C涂层的石墨化程度提高,晶粒变大,SiC纤维单丝体电导率由0.745Ω~(-1)·cm~(-1)升到6.289Ω~(-1)·cm~(-1);SiC纤维编制体的复介电常数实部由90升到132,介电损耗由0.95升到1.14,其中虚部由87升到150.实部增大与载流子浓度增大有关,虚部增大与材料漏导电有关.认为这是SiC纤维表面沉积的C层使纤维电导率增大所致.直流电导损耗足其主要损耗机制.     

热蒸发锌粉法制备半导体氧化锌纳米线的研究

采用热蒸发锌(Zn)粉的方法,制备出高产量的由半导体氧化锌纳米线组成的蒲公英花状和四角锥状纳米结构.利用SEM、TEM和X射线衍射对产物的形貌及结构进行了分析.结果表明,所生成的是具有六方结构的单晶ZnO纳米线.纳米线长约5-10μm,根部直径较粗,约110-120nm;梢部较细,约25-30nm,其生长机制为气-固(VS)机制.     

牙齿组织工程研究近况

牙齿组织工程学是指利用体外和体内培养的手段从单细胞获得整个牙齿的组织工程手段.其关键之处是获得具有较强生长和分化能力的种子细胞、优选较为适宜的支架材料,以及构建有较强再生能力的细胞-支架复合体.     

Color indicator of cuprate superconductivity observed by polarized light microscopy

A common mineralogical technique for identifying individual crystals in a heterogeneous, polycrystalline sample involves the observation at room temperature of their colors in reflected polarized light (colors of polarization). Here we present the observation that a brownish yellow (golden) color of polarization is not only characteristic of the YBa₂Cu₃O₇ superconductor, but of the cuprate superconductors in general and is correlated with the occurrence of superconductivity.     

Failure Investigation on Inducer Blades of Locomotive Turbocharger

Damage to varying degrees including fracture, cracking, and scraping occurred on inducer blades used in a locomotive turbocharger which had run for 3626 km. The blade fracture was formed by the propagation of axial and radial cracks forming an L-shape. Fractography investigation indicates that the axial fracture mode of the blade was by fatigue. The radial fracture was formed by one instantaneous crack. A strike dent was present on the leading edge of the fractured blade and this dent became the initiation site of fatigue crack. Failure of other blades was subsequent to the original fracture.     

基于叶尖定时技术的叶轮叶片动态监测研究现状

叶轮作为旋转机械的核心部件之一,在复杂恶劣的工况中容易使叶片产生振动,进而引发疲劳断裂等失效形式,因此对叶片振动进行状态监测具有重要意义。非接触式的叶尖定时技术具有同时监测整级叶片的优势,为叶片振动及损伤诊断提供了有效方式。本文从叶尖定时传感、叶片振动及损伤监测等三个方面对国内外研究现状进行综述,总结了当前研究中存在的不足,并就叶尖定时技术及叶片健康监测的发展方向进行了展望。     

叶片局部损伤对大型水平轴风力机静动态特性影响的仿真分析

基于参数化整机模型研究风力机的静态和动态特性,以及叶片局部损伤对单叶片和整机的静动态特性影响规律,揭示叶片局部损伤与这些特性的关系。使用ANSYS的APDL语言,实现MW级水平轴风力机复合材料叶片的参数化建模;采用公共几何元素、连接单元和自由度耦合等方法,组建包含叶片、轮毂、塔架等部件的整机有限元模型。计算分析了重力、离心力和风压力共同作用下正常整机和包含叶片局部损伤的整机在迎风位置时的静态响应。比较了正常和损伤状态下根部固定单叶片和装入整机中叶片的动态应变响应。研究表明:对根部固定的单叶片,风轮面内的动态应变响应随迎风面损伤程度的增大而减小;对整机中的叶片,垂直风轮面的动态应变响应随迎风面损伤程度的增大而增大。研究方法和结论对大型水平轴风力机叶片损伤的在线监测具有重要 意义。     

Failure of a low pressure turbine rotor blade of an aeroengine

During a test run of an aeroengine, a low-pressure turbine rotor blade had failed. The turbine blades were made of Ni-base superalloy of CM 247 LC grade and fabricated by DS investment casting. The blades were coated with platinum aluminide. Investigation revealed that the blade had failed by fatigue. It was concluded that the coating on the blade had developed cracks due to excessive bending/vibration, which in turn propagated by fatigue leading to the failure.     

Comparative analysis of steady state heat transfer in a TBC and functionally graded air cooled gas turbine blade

Internal cooling passages and thermal barrier coatings (TBCs) are presently used to control metal temperatures in gas turbine blades. Functionally graded materials (FGMs), which are typically mixtures of ceramic and metal, have been proposed for use in turbine blades because they possess smooth property gradients thereby rendering them more durable under thermal loads. In the present work, a functionally graded model of an air-cooled turbine blade with airfoil geometry conforming to the NACA0012 is developed which is then used in a finite element algorithm to obtain a non-linear steady state solution to the heat equation for the blade under convection and radiation boundary conditions. The effects of external gas temperature, coolant temperature, surface emissivity changes and different average ceramic/metal content of the blade on the temperature distributions are examined. Simulations are also carried out to compare cooling effectiveness of functionally graded blades with that of blades having TBC. The results highlight the effect of including radiation in the simulation and also indicate that external gas temperature influences the blade heat transfer more strongly. It is also seen that graded blades with about 70% ceramic content can deliver better cooling effectiveness than conventional blades with TBC.     

Generating vivid colors on red-green-blue-white electonic-paper display

Color characteristics of an RGBW (red, green, blue, white) electrophoretic display (EPD) prototype developed by Samsung Electronics are analyzed. EPD shows strong crosstalk between subpixels because of both the fringe field between subpixels and the scattering phenomena at the display surface. An RGB-to-RGBW color-decomposition algorithm optimized to EPD characteristics is developed that compensates for color deterioration due to the fringe field and scattering phenomena. For the four-color-decomposition algorithm, white is added to the primary colors to enhance the reflectance of the vivid colors while minimizing chroma loss. The psychophysical experimental result shows that images rendered with the algorithms developed in this study are preferred more than 90% of the time over those rendered with algorithms from previous studies. This research proves that, in spite of the limited physical property of EPD, the color quality can be improved dramatically through the use of well-designed color-rendering algorithms.     

浅谈航空发动机叶片几何参数测试计量保障体系

对航空发动机叶片几何参数进行了定义和分类,基于叶片几何参数精密测量的重要性、型面参数测量的复杂性和叶片几何参数测量评价的现状,详细介绍了航空发动机叶片几何参数测试计量保障体系构建的需求,提出建立覆盖航空发动机叶片几何参数的测试计量保障体系,并对该体系的内涵和架构思路进行了阐述,为航空发动机装备叶片零部件数字化设计制造、...     

Flexible Blade‐Coated Multicolor Polymer Light‐Emitting Diodes for Optoelectronic Sensors

A method to print two materials of different functionality during the same printing step is presented. In printed electronics, devices are built layer by layer and conventionally only one type of material is deposited in one pass. Here, the challenges involving printing of two emissive materials to form polymer light‐emitting diodes (PLEDs) that emit light of different wavelengths without any significant changes in the device characteristics are described. The surface‐energy‐patterning technique is utilized to print materials in regions of interest. This technique proves beneficial in reducing the amount of ink used during blade coating and improving the reproducibility of printed films. A variety of colors (green, red, and near‐infrared) are demonstrated and characterized. This is the first known attempt to print multiple materials by blade coating. These devices are further used in conjunction with a commercially available photodiode to perform blood oxygenation measurements on the wrist, where common accessories are worn. Prior to actual application, the threshold conditions for each color are discussed, in order to acquire a stable and reproducible photoplethysmogram (PPG) signal. Finally, based on the conditions, PPG and oxygenation measurements are successfully performed on the wrist with green and red PLEDs.     

Failure Analysis of High-Pressure Compressor Blade in an Aero Gas Turbine Engine

Failure of high-pressure compressor rotor blade in an aero gas turbine engine is analyzed to determine its root cause. Forensic and metallurgical investigations are carried out on the blade and failed parts. The failure of the platform ladder is found to the first in the chain of events that led to the compressor blade failure. The mode of failure in the blade is found to be fatigue and has originated from the damaged region on the leading edge caused by dislodgement of platform ladder. The failure has caused extensive damages in high-pressure compressor module and also in downstream turbine blades as a secondary effect.