Unique features of the basal cells of human prostate epithelium

The prostate gland is globally composed of epithelium and stroma. The epithelium plays an important role in the development of both benign and malignant disorders while the stroma is involved in benign prostatic hyperplasia. While the prostatic epithelium of the majority of laboratory animals is well recognized as a pseudostratified columnar, the classification of the human prostatic epithelium is controversial. Moreover, the role of the basal cells of the human prostatic epithelium is still uncertain. These cells have been described as undifferentiated cells, precursors of luminal cells, reserve and myoepithelial cells. The objective of the present study was to assess the similarities and/or differences between the epithelium of the human prostate and that of other laboratory animals and thus derive information about the potential functions of basal cells in the human prostate. In the human, basal cells form a continuous layer of cells resting on the basement membrane and upon which rests a layer of luminal cells. This results in a stratified columnar epithelium of two layers of cells, unlike the sporadic appearance of basal cells observed in other species where it results in a pseudostratified epithelium. In addition, the ratio of basal to luminal cells in the human is about 1:1, while the average ratio in the other animal species examined is about 1:7. Furthermore, the gap junctional proteins connexin 26 and 43, are present between basal and luminal cells in the human, thus suggesting that these cells communicate directly with each other. In addition, the ultrastructure of the human basal cells shows morphological evidence of differentiated but not of undifferentiated cells. Moreover, the presence of junction-like structures between adjacent basal cells suggests that these cells form a blood-prostate barrier. In this way, basal cells could prevent substances derived from the blood from directly coming in contact with the luminal cells. Human basal cells could thus regulate functions of the luminal cells by being part of a two-cell mechanism somewhat analogous to thecal and granulosa cells in the ovary.     

咽颌运动模式仿生胸鳍的建模及试验研究

从咽颌运动模式鱼类胸鳍的骨骼结构和神经肌肉控制机理出发,充分发挥导边鳍条和后缘边鳍条的引导作用,设计一套新型的柔性仿生胸鳍,建立此仿生胸鳍的样机及其运动学和动力学模型。并对仿生胸鳍的推进运动进行了仿真分析和试验研究。将上述仿生胸鳍推进运动的仿真结果、试验结果以及实际胸鳍推进运动的观测结果进行了比较研究可以看出,所建立的仿生胸鳍数学模型是合理、有效的,能够较好地仿真仿生胸鳍的推进运动,同时从中也可以看出,所建立的胸鳍仿生机构能够较好地模拟鱼类胸鳍的推进运动。     

齿形几何参数对直通篦齿封严泄漏特性的影响

建立不同封严间隙、齿高、齿距、齿宽、齿数等几何参数的直通篦齿模型,通过数值方法分析不同气动参数(进出口落压比)条件下几何参数变化对其泄漏特性的影响。结果表明,流量系数随落压比的增大而增大,随着封严间隙、齿宽的增大而增大,随着齿高、齿距、齿数的增大而减小。5个几何参数中,封严间隙对流量系数的影响最大,其次为齿数、齿距、齿高、齿宽。利用最小二乘法拟合得到流量系数与几何参数及气动参数的准则关系式,拟合公式计算结果与数值模拟结果吻合较好,可用于篦齿的工程设计计算。     

散热器空气侧百叶窗翅片结构参数优化

对散热器空气侧的百叶窗翅片建立三维流固耦合的模型,运用Laminar方法进行数值模拟,结果表明传热与压降特性与实验关联式吻合较好,模型得以验证;为进一步阐明汽车内散热器空气侧的强化传热翅片的性能,分别考察了不同的翅片高度、窗翅高度、翅片厚度和翅片节距等结构参数对传热系数和压降的影响,得到了一组综合性能较好的百叶窗翅片结构参数。     

Morphology of olfactory epithelium in humans and other vertebrates.

Human olfactory epithelium is similar in organization and cell morphology to that of most vertebrate species. The epithelium has a pseudostratified columnar organization and consists of olfactory neurons, supporting and basal cells. Near the mucosal surface there are also microvillar cells. These cells have neuron-like features and may be chemoreceptors. Human olfactory epithelium is not a uniform sensory sheet. Patches of non-sensory tissue often appear in what was thought to be a purely olfactory region. The significance of these patches has not been determined, but they could reflect exposure to environment agents or changes that occur during the normal aging process. In order to better understand the human olfactory system, further knowledge of the normal structure is necessary. This review addresses the morphology of the human olfactory epithelium and the remarkable plasticity of the vertebrate olfactory system.     

Experimental study on the characteristics of longitudinal fin air-heating vaporizers in different seasons

Air-heating vaporizers are usually used to regasify LNG at satellite areas because of the small demand for natural gas there. The common type of air heating vaporizer which exists in the market is the longitudinally finned type with 8 fins, 50mm fin length and 2mm fin thickness. To contribute in developing an efficient air-heating vaporizer, experiment on finned type air-heating vaporizer using 8 fins, 50mm fin length with 2mm fin thickness (8fin50le)-which exist in the market-and 4 fins, 75mm fin length with 2mm fin thickness (4fin75le), which is proposed, were conducted. Then, both types of vaporizers are compared. The experiments were conducted in one hour by varying the ambient condition and the length of the vaporizer. The ambient air was controlled so that it has the same condition (same temperature, humidity and air velocity) with air condition in every season available and the length was varied 4000mm, 6000mm and 8000mm for each type of vaporizer. Additional experiment with longer duration, i.e., 4 hours and in a single room condition was conducted to validate the previous result. In this experiment, the main aspects in analyzing the characteristics of the air heating vaporizer are the inlet-outlet enthalpy difference and the outlet temperature of the working fluid. LN₂ is used to substitute LNG for safety reasons. The results show that the characteristics of the finned type 4fin75le vaporizer are comparable to the finned type 8fin50le vaporizer.     

水冷盘式制动器散热结构优化

为提高水冷盘式制动器散热性能,基于强化对流传热原理,通过添加扰流柱对制动器散热结构进行优化,设计了4种扰流柱散热结构,运用CFD方法模拟制动盘流固耦合传热过程,采用Fluent软件进行热流固耦合仿真计算,获得制动盘温度特性和换热特性以及流动阻力特性,并使用综合性能评价因子对不同扰流柱散热结构进行评价。结果表明:通过在安装盘水槽内添加扰流柱可以有效地提高水冷盘式制动器的散热效果;在相同的工作条件下,正三角形扰流柱散热结构的盘面温度最低,平均努塞尔数与流动阻力最高,其综合散热性能较圆形、椭圆形以及水滴形扰流柱散热结构分别提高了3.4%,2.4%和4.4%,较无扰流柱散热结构提高了6.7%,正三角形扰流柱散热结构具有更好的综合散热性能。研究结果为水冷盘式制动器散热结构的优化设计提供了参考。     

Structural changes and cell properties of human ovarian surface epithelium in ovarian pathophysiology

The surface epithelial cells of the ovary, which are modified peritoneal cells, form a single, focally pseudostratified layer. The Müllerian ducts differentiate after invagination of the coelomic mesothelium over the gonadal ridges during the 6th week of embryonic life. On the basis of the embryologically putative Müllerian potential of this epithelium, endometriosis can be explained by coelomic metaplasia from the peritoneum, including ovarian surface epithelium. Some pelvic endometriosis specimens have shown that epithelial cells on the ovary or pelvis are serially changed to endometriotic gland cells. Immunohistochemistry as well as scanning electron microscopy also reinforce the light-microscopical findings. A three-dimensional culture system demonstrated that human ovarian surface epithelial cells exhibited a glandular-stromal structure when they were cocultured with endometrial stromal cells in an estrogen-rich environment. Ovarian carcinomas in the epithelial-stromal category are thought to arise from the surface epithelium and its inclusions. The ovarian surface epithelium is physiologically involved in follicular rupture, oocyte release, and the subsequent repair of follicle wall during reproductive age. Simultaneously, ovulation may cause a loss of integrity of the surface epithelium, followed by accumulation of multiple mutations. The cortical invagination, surface stromal proliferation, and Müllerian differentiation of these cells are likely not to be an early step in the cancer development. However, the inclusion cysts are closely related with carcinogenesis because they are significantly more common in ovaries contralateral to those containing epithelial cancers than in control ovaries. As an in vitro study, ovarian carcinoma cell lines were established from simian virus 40 large T antigen-transformed human surface epithelial cells of the ovary. Further investigations of these cell lines may lead to insights into the preneoplastic and early stages of carcinomas. To clarify the pathogenesis of endometriosis and epithelial ovarian cancer, specifically designed studies of ovarian surface epithelium are required.     

Optimization of a reversed trapezoidal fin using a 2-D analytic method

A reversed trapezoidal fin with variable fin base thickness is optimized based on the fixed fin volume by using a two-dimensional analytic method. The variation of temperature along the normalized Y position at the fin tip is presented. For fixed fin volumes, the maximum heat loss, the corresponding optimum fin effectiveness, fin base height and fin tip length as a function of the fin base thickness, fin shape factor and the fin volume are presented. One of the results shows that both the optimum heat loss and the optimum fin length increase with the increase of the value of fin shape factor.     

锯齿形翅片散热器风冷性能试验研究

文中从试验的角度研究了锯齿形翅片散热器的风冷性能。锯齿形翅片散热器具有结构复杂、不易仿真实施的特点。文中系统介绍了锯齿形风冷散热器的典型结构形式以及风冷性能测试系统原理、性能和测试分析结果,从试验实测的角度研究了锯齿形翅片散热器的应用选型及其与散热量、风量、风压等的关系,分析了翅片参数(翅高、翅宽、翅片节距)对散热性能的影响,对电子产品散热的风冷设计具有较高的参考价值。     

Multiphoton microscopic imaging of adipose tissue based on second-harmonic generation and two-photon excited fluorescence

The fresh adipose tissue was investigated by the use of multiphoton microscopy (MPM) based on two-photon excited fluorescence and second-harmonic generation (SHG). Microstructure of collagen and adipose cells in the adipose tissue is clearly imaged at a subcellular level with the excitation light wavelengths of 850 and 730 nm, respectively. The emission spectrum of collagen SHG signal and NADH and FAD fluorescence signal can also be obtained, which can be used to quantify the content of collagen and adipose cells and reflect the degree of pathological changes when comparing normal tissue with abnormal adipose tissue in the same condition. The results indicate that MPM has the potential to be applied to investigate the adipose tissue and can be used in the research field of lipid and connective tissues.     

The blood-testis barrier and Sertoli cell junctions: structural considerations.

In this review, a few well-established axioms have been challenged while others were viewed from a new perspective. The extensive literature on the blood-testis barrier has been scrutinized to help probe its mechanics and hopefully to promote understanding of the constant adaptation of the barrier function to germ cell development. Our principal conclusions are as follows: (1) Although the barrier zonule is topographically located at the base of the seminiferous epithelium it actually encircles the apex of the Sertoli cell. Consequently the long irregular processes specialized in holding and shaping the developing germ cells should be considered as apical appendages analogous to microvilli. (2) The development of the barrier zonule does not coincide with the appearance of a particular class of germ cells. (3) The barrier compartmentalizes the epithelium into only two cellular compartments: basal and lumenal. (4) Although the blood-testis barrier does sequester germ cells usually considered antigenic, immunoregulator factors other than the physical barrier seem to be involved in preventing autoimmune orchitis. (5) Structurally, a Sertoli cell junctional complex is composed of occluding, gap, close, and adhering junctions. The Sertoli cell membrane segments facing germ cells are presumably included in the continuum of the Sertoli cell junctional complex that extends all over the lateral and apical Sertoli cell membranes. (6) The modulation (i.e., formation and dismantling) of the junctions in a baso-apical direction is characteristic of the seminiferous epithelium and may be dictated by germ cell differentiation. The formation of tubulobulbar complexes and the following internalization of junction vesicles conceivably represent sequential steps of a single intricate junction elimination process that involves junction membrane segments from different cell types as part of a continual cell membrane recycling system. (7) The preferential association of junctional particles with one or the other fracture-face reflect a response to various stimuli including seasonal breeding. Changes in the affinity of the particles are generally coincidental with cytoskeletal changes. However, changes in the cytoskeleton are not necessarily accompanied by permeability changes. The number of strands seems to reflect neither the junctional permeability nor the transepithelial resistance. The diverse orientation of the strands seems to be related to the plasticity of the Sertoli cell occluding zonule. (8) Cooperation between all constituents (Sertoli cells, myoid cells, cell substratum, and germ cells) of the epithelium seems essential for the barrier zonule to function in synchrony with the germ cell differentiation.(ABSTRACT TRUNCATED AT 400 WORDS)     

A Comparison of Four Solution Methods for the Analysis of a Trapezoidal Fin

A comparison is made of the temperature profile and the heat loss from a trapezoidal fin using four methods. These four methods are the one- and two-dimensional analytical, the two-dimensional finite difference and a two-dimensional modified finite difference method. The two-dimensional analytical method was arbitrarily chosen as the reference. The non-dimensional fin length is restricted to be less than 2 to prevent errors which might occur due to large values of Δx in the finite difference methods. The values of the Biot number range from 0.01 to 1.0 while the thermal conductivity of the fin and fin’s convection coefficients are assumed constant. The results show that (1) in the view of the heat loss from the trapezoidal fin, all four methods can be used to obtain the solutions within 3% with each other for the given range of Biot number and the non-dimensional fin length, (2) for the non-dimensional temperature, the one-dimensional analytical method does not produce good results as compared to the other three methods when the Biot number is 1.0, and (3) by using a two-dimensional modified finite difference method instead of the two-dimensional finite difference method, the relative difference in the heat loss as compared to a two-dimensional analytical method is reduced considerably.     

Choroid plexus: target for polypeptides and site of their synthesis

Choroid plexus (CP) is an important target organ for polypeptides. The fenestrated phenotype of choroidal endothelium facilitates the penetration of blood-borne polypeptides across the capillary walls. Thus, both circulating and cerebrospinal fluid (CSF)-borne polypeptides can reach their receptors on choroidal epithelium. Several polypeptides have been demonstrated to regulate CSF formation by controlling blood flow to choroid plexus and/or the activity of ion transport in choroidal epithelium. However, many ligand-receptor interactions occurring in the CP are not involved in the regulation of fluid secretion. Increasing evidence suggests that the choroidal epithelium plays an important role in hormonal signaling via a receptor-mediated transport into the brain (e.g., leptin) and helps to clear certain CSF-borne polypeptides (e.g., soluble amyloid beta-protein). Thus, impaired choroidal transport or insufficient clearance of polypeptides may contribute to pathogenesis of systemic or central nervous system (CNS) disorders, such as obesity or Alzheimer's disease. CP epithelium is not only a target but is also a source of neuropeptides, growth factors, and cytokines in the CNS. These polypeptides following their release into the CSF may exert distal, endocrine-like effects on target cells in the brain due to bulk flow of this fluid. Distinct temporal patterns of choroidal expression of several polypeptides are observed during brain development and in various CNS disorders, including traumatic brain injury and ischemia. Therefore, it is proposed that the CP plays an integral role not only in normal brain functioning, but also in the recovery from the injury. This review attempts to critically analyze the available data to support the above hypothesis.     

Optimization of a rectangular profile annular fin based on fixed fin height

The optimum performance and fin length of a rectangular profile annular fin are presented using a variations separation method. For fixed fin height, the optimum fin length and efficiency are arbitrarily defined as those for which the heat loss is in the range between 90% and 99% of the maximum heat loss. The maximum heat loss, the maximum effectiveness, the minimum fin resistance, the optimum fin length and the optimum efficiency are presented as a function of the inside fluid convection characteristic number, fin base thickness, fin height and ambient convection characteristic number. One of the results shows that the optimum fin length decreases almost linearly with the increase of the fin base thickness.     

Optimal architecture of heat generating pieces in a fin

This paper documents the optimal architecture of heat generating pieces connected to and cooled in a circular-shaped fin. Relying on the constructal theory, the optimal distribution of multiple heat sources is obtained by minimizing the thermal resistance of the fin. Since the heat sources are contemplated as electronic devices with uniform heat generation, the minimization of the thermal resistance is indicated by minimization of the hot spot (peak) temperature. Temperature fields in the fin and in the heat sources are calculated using a finite elements approach of MATLAB PDE toolbox. Comparison among the considered configurations reveals that the regular configurations of the heat sources commonly used in cooling industry are not optimal and must be avoided. Optimal configurations such as triangular arrangement of heat sources are proposed to replace the unfavorable configurations.     

基于ICEPAK仿真的散热器结构热设计研究

文中利用ICEPAK软件对多密度高功率芯片散热器结构进行了热设计研究。研究确立了影响翅片散热器散热性能的关键尺寸设计参数,如基板厚度、翅片高度、翅片厚度和翅片间距等,并得出了各尺寸设计参数对其散热效果的影响趋势,确定了散热器结构的最佳布局方案。此外,研究还建立了最佳布局的散热器结构实物并进行了高低温试验以模拟其高温散热情况。通过实验数据对比发现,仿真计算结果与实际较为吻合,进而验证了ICEPAK软件在电子设备散热设计方面的准确性与可靠性。     

Comparison of performances of the various shapes of asymmetric fins

A comparison between the heat loss of the asymmetric triangular fin and the asymmetric trapezoidal fins which have various slopes of the fin’s upper lateral side is performed. The relation between the slope factor of the fin and the non-dimensional fin length for equal amount of heat loss is shown. Further, the relation between the Biot number and the non-dimensional fin length for equal amount of heat loss is given. For these analyses, a forced analytic method is used. In particular, the same equation is used for both the asymmetric triangular fin and the asymmetric trapezoidal fins just by adjusting the value of the slope factor. It is shown that this equation can also be applied to a rectangular fin with very good accuracy. The base temperature, thermal conductivity of fin’s material and the heat transfer coefficient are assumed constant.     

欠驱动柔性胸鳍仿生设计及仿真

为了进一步提高咽颌运动模式鱼类胸鳍仿生机构的性能,以实际鱼类胸鳍的结构和驱动控制机理为基础,采用欠驱动技术设计了一套新型的柔性胸鳍仿生机构,建立其运动学和动力学模型,并采用Matlab对其性能进行了仿真分析。从仿真结果来看,所建立的新型柔性胸鳍仿生机构及其运动学、动力学模型是合理、有效的。它不但能够较好的模拟胸鳍的各种操纵运动,而且减少了驱动装置的数量,降低了系统的复杂性。从而为深入研究鱼类胸鳍的推进机理和新型水下操纵工具的设计提供了一定的基础和保障。     

鲤鱼尾鳍瞬时三维形态测量

提出了鱼在自由游动状态下尾鳍实时三维形貌的测量方法。将影栅云纹投射在鲤鱼尾鳍表面,产生包含三维形态信息的云纹,由高速摄像机采集瞬时序列变形条纹,运用傅立叶变换轮廓术对序列图像进行处理,并将相位解包裹方法用于动态过程瞬时三维相位场的相位展开中,重建了鲤鱼尾鳍自由游动的瞬时三维形态,再现了尾鳍的连续摆动过程。