Developmental changes in the ultrastructure of the Sauromatum guttatum (Araceae) mitochondria

Electron microscopic studies show that the electron density of the mitochondria of the thermogenic appendix of Sauromatum guttatum inflorescences changes during development. Two to 3 days before heat-production, the mitochondria accumulate osmiophilic, electron-dense material between the inner and outer membranes. During heat-production and the release of volatiles compounds the osmiophilic material disappears from the inter membrane space. Deposits with the same electron density are also found in the endoplasmic reticulum. It is concluded that the mitochondria may also have the capacity to accumulate that material in the inter membrane space.     

非酶糖基化致衰老小鼠肝脏超微结构改变的研究

非酶糖基化和氧化反应是羰基毒化衰老学说的基本内容,已成为21世纪衰老理论与应用研究的热点。已有许多报道非酶糖基化反应产生的高级糖基化终末产物(advanced glycation endproducts,AGE)与机体正常老化以及糖尿病、阿尔茨海默病等老年性疾病发生有关。而且证明D-半乳糖致急性衰老也     

Microscopy and microanalysis study of the indium (In) behavior in the intestinal mucosa, the liver, the kidney and the testicle

Several studies have demonstrated that In used in medicine has several impacts on organs like spleen and lungs after its systemic administration. In the present study, ultrastructural and microanalytical methods were used to investigate the impact of the presence of this element in the intestinal mucosa, the liver, the kidney and the testicle after its administration in two ways. After intraperitoneal administration, In was selectively concentrated in the lysosomes of hepatocytes, of tubular proximal convoluted cells and of Sertoli and Leydig cells. After intragastric administration, ultrastructural study showed that this element was concentrated in the lysosomes of duodenal enterocytes. Microanalytical methods showed that In was precipitated in those organelles in the form of insoluble phosphate salts. Similarly to other studies, it seemed that since In is a foreign element for the organism, it was precipitated in lysosomes, very probably due to the activity of an intralysosomal enzyme the acid phosphatase, to avoid its invasion to organism via the blood. This mechanism of precipitation of the mineral elements is of great interest in the process of defensive reaction of the organism against intoxication by foreign elements.     

Analytical expressions for tunnel currents in metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) structures in a two-band model

A new closed-form approximation for the tunnel current in MIM and MIS structures is derived assuming a general E-k relationship and barrier shape. An upper limit for the error involved in this approximation is estimated. The existing closed-form expressions for the tunnel currents are discussed and their limitations are exposed.     

稀土元素钕对油菜超微结构的影响

电镜观察表明：低浓度的钕对完全营养培养的油菜顶叶叶尖细胞的叶绿体片层结构有明赤的改善作用,而高浓度的钕会引起结构损坏。适当浓度的钕能对缺钙油菜苗受损的细胞有修复作用,这表明钕有部分替代钙的作用。钕对油菜主根根尖细胞的作用与对顶叶叶尖细胞作用类似,但对根细胞超微结构影响更为明显。     

两种小菜蛾寄生蜂毒液器官超微结构的比较

应用超薄切片和电镜技术，观察比较了两种小菜蛾的内寄生蜂——小菜蛾盘绒茧蜂和半闭弯尾姬蜂毒液器官的形态结构。两种蜂的毒液器官均由一个毒囊和两条毒腺组成，但毒腺与毒囊的连接位点不同，毒腺分别接于毒囊的基部和顶端。它们的毒腺均由分泌细胞、退化的外胚层细胞和环腔的内膜三层结构构成，分泌细胞内含司分泌毒液的囊状细胞器及大量的内质网、线粒体、高尔基体、溶酶体和液泡。半闭弯尾姬蜂的分泌细胞内有分支的细胞核。小菜蛾盘绒茧蜂的毒囊由肌肉鞘和扁平细胞层构成，内膜呈波浪状内突并沿囊腔有几丁质增厚；半闭弯尾姬蜂的毒囊由肌肉鞘、分泌细胞和扁平细胞三层构成，分泌细胞基部内陷成一系列大的突起，这些结构与雌蜂的分泌和排出毒液的行为密切相关。在衰老的小菜蛾盘绒茧蜂的腺细胞中还存在大量的髓样体。本文就两种寄生蜂毒液器官的生物学、细胞生理学及相关的分类进化的意义进行了讨论。     

Eye ultrastructure in the pollen-feeding beetle, Xanthochroa luteipennis (Coleoptera: Cucujiformia: Oedemeridae)

The pollen-consuming beetle Xanthochroa luteipennis, which belongs to the family Oedemeridae, possesses a nearly spherical eye of approximately 400 microm in diameter. The eye contains 750-800, mostly hexagonal ommatidia, which are of the acone apposition type and have an open rhabdom. A well-developed pupil mechanism controls the light flux to the rhabdom. The pupil is formed with the help of screening pigment translocations, involving primary and secondary (accessory) pigment cells. Cross-sections of rhabdoms reveal that they are developed as ring-like structures, made up of the rhabdomeres of six retinula cells, surrounding a rod-like inner column of two fused rhabdomeres. Rhabdoms of ommatidia in the middle of the eye differ somewhat from those in more peripheral areas. In the former the central rhabdom is circular in cross-section, while in the latter it is spindle-shaped. The rhabdom organization in combination with the distal pupil mechanism is seen as an adaptation to maximize photon capture under a variety of ambient light intensities, for Oedemerid beetles are commonly active during the day as well as the night.     

漩涡征在新生儿肠旋转不良诊断中的作用探讨

目的：分析漩涡征在诊断新生儿肠旋转不良有无合并中肠扭转的意义。方法：应用超声检查肠系膜上动脉和肠系膜上静脉的关系来明确有无漩涡征的存在。结果：所有患儿超声检查有漩涡征,于术证实为肠旋转不良伴有中肠扭转,39例患儿均存活,无严重术后并发症的发生,1例全中肠坏死,放弃治疗。结论：腹部超声检查漩涡征的仔在对先天性肠旋转不良有无合并中肠扭转有临床意义。     

Thru characteristics of a coaxial gap (FDTD model and measurements)

Thru characteristics of a coaxial cable interrupted by a small gap are modeled and measured. Finite-difference time-domain (FDTD) modeling is applied in cylindrical coordinates to semirigid coaxial cable and to the intervening gap material. Both dispersive and nondispersive gap materials are investigated. Gap loss and phase shift are accurately predicted by this two-dimensional model which accounts for TEM and TM modes in the gap and coaxial apertures. An application of the model is to establish reference data for thin sample permittivity or moisture measurements     

纳米氧化锌对鲤鱼鳃显微和超微结构的影响

采用光镜和透射电镜技术,探讨了不同浓度纳米氧化锌暴露对鲤鱼幼鱼鳃显微和超微结构的影响.暴露组纳米氧化锌浓度分别为5、10、20、50、100 mg·L-1,同时设对照组,连续暴露21d,取鳃制备切片,进行光镜和透射电镜观察.结果表明,21d后纳米氧化锌暴露组鲤鱼鱼鳃部均有不同程度的损伤,石蜡切片上可观察到暴露组鱼鳃上皮...     

Potential and current density distributions of cranialelectrotherapy stimulation (CES) in a four-concentric-spheres model

Cranial electrotherapy stimulation (CES) has been successfully used for treatment of many psychiatric diseases. Its noninvasive nature is its major advantage over other forms of treatments such as drugs. It is postulated that the low electric current of CES causes the release of neurotransmitters. However, the current pathways have not been extensively investigated. In this paper, analytical and numerical methods are used to determine the distribution of potential and current density in a four zone concentric spheres model of the human head when excited by two electrodes diametrically opposite to each other. Because of the azimuthal symmetry, which is assumed in this study, a two-dimensional (2-D) finite difference approximation is derived in the spherical grid. The current density distribution is projected around the center of the model, where the thalamus is modeled as a concentric sphere. All dimensions and electrical properties of the model are adapted from clinical data. Results of this simulation indicate that, in contrast to previous beliefs, a small fraction of the CES current does reach the thalamic area and may facilitate the release of neurotransmitters     

Research of low-frequency model of a low noise microwave frequency (phase) detector

The analysis of a low frequency model of an original microwave frequency (phase) detector with amplitude modulator, shift generator and subtracting unit is performed and the results of experimental research are presented. This research leads to a conclusion on the possibility of suppressing the most intensive phase noise at the output of the considered frequency (phase) detector.     

A plasticity-based model of material removal in chemical-mechanicalpolishing (CMP)

It is well known that the chemical reaction between an oxide layer and a water-based slurry produces a softer hydroxylated interface layer. During chemical-mechanical polishing (CMP), it is assumed that material removal occurs by the plastic deformation of this interface layer. In this paper, the behavior of the hydroxylated layer is modeled as a perfectly plastic, material, and a mechanistic model for material removal rate (MRR) in CMP is developed. The deformation profile of the soft pad is approximated as the bending of a thin elastic beam. In addition to the dependence of MRR on pressure and relative velocity, the proposed plasticity-based model is also capable of delineating the effects of pad and slurry properties. The plasticity-based model is utilized to explore the effects of various design parameters (e.g., abrasive shape, size and concentration, and pad stiffness) on the MRR. Model predictions are compared with existing experimental observations from glass polishing, lapping, and CMP     

Analytical model of busy channel multiple access (BCMA) for packetradio networks in a local environment

The performance obtainable with busy-channel multiple access (BCMA) techniques is analytically defined in the context of multichannel local radio networks. Network behavior is characterized in terms of throughput and transmission delay when a single radiofrequency channel is shared among many users, thought to be within the range of a central station, suitably located in the local area. The analytical model is based on a suitable Markov model for the generic terminal, and it is assumed that the traffic presented to the common channel conforms to a Poisson distribution. An analytical evaluation of throughput as a function of offered traffic and average transmission delay is presented. The numerical results obtained are for a particular case of BCMA, the well-known busy-tone multiple access (BTMA). In this example, the analytical model proposed allows fast performance evaluation and suitable comparison with CSMA and ALOHA protocol techniques and evaluation of the capture effect     

SiC单晶片化学机械抛光工艺参数模型的研究

Firstly, this paper presents an orthogonal test of six factors and five levels, called the chemical mechanical polishing （CMP） process parameters experiment, for determining the best process parameters and ranking the influencing factors from primary to secondary. The three most important factors are the polishing pressure, the polishing liquid concentration and the relative velocity ratio of polishing disk to polishing carrier. Then, based on this analysis, the three factors and three levels of the quadratic orthogonal regression test are put forward. A math- ematical model impacting the surface roughness has also been set up. Finally, this work has achieved a polished wafer, whose material removal rate （MRR） is in the range of 70-90 nm/h and the surface roughness （Ra） is between 0.3 nm and 0.5 nm.     

(SPACE) distribution and measurement of laboratory and office spacecosts: a financial model

Space Plan Allocation of Costs Equitably (SPACE) is a financial model the authors have developed to identify total operating costs across a corporate or university research and development (R&D) center as a function of space. Because certain kinds of spaces, such as cleanrooms, wet chemistry, physics laboratories and computer centers, cost significantly more to construct and operate and need more infrastructure support than offices or electronic laboratories, one cannot use a flat dollars-per-square-foot charge or a flat dollars-per-person charge and be equitable and accurate in the reflection of costs. The goal of the authors' model is to determine the total cost associated with supporting various technologies used in each class of space. The model can be used to allocate and charge for services as a function of space, and it can also be used to size and benchmark facilities and services organizations. This concept of cost allocations can be used for any type of complex, from office tower to manufacturing and development (M&D) to marketing and sales (M&S)     

Analytical model for high-performance shallow-junction-welltransistor (SJET) with a fully depleted channel structure

An analytical model for a very-shallow-junction-well transistor (SJET) is described. Solving the one-dimensional Poisson equation at the channel region, it was found that the channel depletion-layer charge can be reduced by extending the p-n junction depletion layer width between the well region and the substrate in the SJET. Therefore, in the SJET, the p-well thickness and the substrate bias are very important factors for realizing its high performance. According to this model, larger carrier mobility in the inversion layer and smaller subthreshold swing can be realized in the SJET compared to a conventional MOSFET. Moreover, by controlling the electron injection from the inversion layer to the substrate at high substrate bias, a vertical operating mode in the SJET (VSJET) can also be realized     

广义非局域非线性薛定谔模型的自相似解

在获得一个含变化3-5阶非线性、弱非局域性、增益及非线性增益的广义薛定谔方程的自相似解的基础上,采用数值方法研究了解的稳定性. 结果表明,在同时具有或没有非局域性和5阶非线性的介质中可以形成与传播自相似波; 而且当相位参数远离 时,非局域度和累积衍射将极大影响自相似波的稳定性.     

超宽带基于分组碰撞的多用户干扰模型在ad-hoc网络中的应用

在多用户UWB(超宽带)系统中,为了减小MUI(多用户干扰),提出了一种基于分组碰撞的多用户干扰(PC)模型.这种模型相比较SGA(标准高斯)模型,更适用于用户数量较少,传输速率较低,存在主导地位的干扰时,例如考虑异步网络:ad-hoc网络,更适用于采用PC模型.     

The use of a PID controller to model vecuronium pharmacokineticsand pharmacodynamics during liver transplantation

A four-phase proportional-integral-derivative (PID) controller was evaluated under the extremely unstable conditions of liver transplantation. Vecuronium was delivered to achieve 80%-90% neuromuscular blockade as measured by electromyogram (EMG). The first two controller phases delivered boluses and a constant infusion calculated to rapidly achieve setpoint, followed by a proportional-derivative (PD) phase at 35% from setpoint, and PID within 10% of the setpoint. During liver transplantation, the sources of system instability included large blood losses, temperature changes, and loss of hepatic drug metabolism during removal and replacement. During prolonged surgery, and when blood losses were not severe, the EMG remained within 10% of setpoint. Controller performance was more variable during system instability. Plasma sampling and two-compartment modeling of the infusion and response with a weighting factor for blood loss allowed estimation of the sources and degree of instability for improved design of future controllers