Surface modification of vitreoretinal surgical instruments with layer-by-layer films

Commercially available vitreoretinal surgical forceps were modified with layer‐by‐layer (LbL) films designed to render them the ability to specifically adhere human the inner limiting membrane. Surgical forceps with two different geometries were etched, polished, and silanized before deposition of the films composed of poly (allylamine hydrochloride), poly (styrene sulfonate), and cationic gold nanoparticles. Stability and integrity of the LbL films was scrutinized by exposing the modified forceps to commercial disinfectant Cidex‐OPA and then placing the instruments in a physiological‐like HEPES buffer (pH 7.4, 5 mM, 154 mM NaCl). Surface topography analysis with scanning electron microscopy revealed that the geometry of the surgical instrument may affect the integrity of the film. Analysis of the HEPES buffer with inductively coupled plasma mass spectrometry demonstrated that gold nanoparticles did not leach from the LbL film after 60 min. SCANNING 33:397–401, 2011. © 2011 Wiley Periodicals, Inc.     

An objective method for measuring fluorescence of individual sperm cells labelled with 1-anilinonaphthalene-8-sulphonate (ANS) by means of photomicrography and densitometry

A method is presented for measuring the degree of fluorescence of sperm cells labelled with 1-anilinonaphthalene-8-sulphonate (ANS). Labelled spermatozoa were subjected to incident-light u.v. illumination and the fluorescent image was photographed. Densitometry of the photographic film yielded values for individual sperm heads, and the mean value for ten cells formed the unit of data for parametric statistical analysis. The method is both objective and precise, and was used to distinguish between treatments applied to the spermatozoa. It is believed that the method has a wide application as an inexpensive means of fluorimetry.     

Ultrastructure of bovine sperm chromatin

Mammalian semen chromatin comprises DNA, protamine, and, at lower levels, other proteins. This constitution confers intense compaction to the chromatin, helping to protect the DNA and causing the head of the sperm to be very small, facilitating the safe transport of its genetic contents. It is known that changes in the sperm chromatin compaction lead to fertility problems in bulls, justifying studies of this structure. Although there are theoretical models of sperm chromatin because of its high compaction, there is no morphological evidence of such models. The aim of this study was to demonstrate the ultrastructure of bovine sperm chromatin in an attempt to corroborate the theoretical chromatin models existing today. The isolated bull sperm heads had their chromatin partially unpacked by chemical treatment using sodium dodecyl sulfate (SDS) and dithiothreitol (DTT) and were then embedded in Epon resin. Using an ultramicrotome, ultrathin sections were obtained, which were contrasted with uranyl acetate and lead citrate, and then viewed under transmission electron microscopy. The methodology used allowed the visualization of toroidal structures interconnected by a filamentous nuclear matrix, which is entirely consistent with the most current theoretical models. Microsc. Res. Tech. 78:1117–1120, 2015. © 2015 Wiley Periodicals, Inc.     

Investigation of fading and recovery of fluorescence intensity at 73·5 K

Fading and recovery of Af-feulgen stained sperm heads are investigated at 73·5 K. The fast fluorescence signals are measured and stored by two coupled transient recorders. 100% recovery was reached after a dark time of 3 s. This shows that the photodecomposition is mainly caused by change of the probability density of energy level and not by destruction of the chromophore groups. The recovery effect allows measurement of the fluorescence intensity of the same sample more than 50 times. Therefore the unaffected spectrum can be measured directly, provided that between the short-term measurements at constant wavelength an appropriate dark phase has been put into operation.     

Interactions of sperm perinuclear theca with the oocyte: implications for oocyte activation,anti-polyspermy defense,and assisted reproduction

Perinuclear theca (PT) is the cytoskeletal coat of mammalian sperm nucleus that is removed from the sperm head at fertilization. PT harbors the sperm borne, oocyte-activating factor (SOAF), a yet-to-be-characterized substance responsible for triggering the signaling cascade of oocyte activation, thought to be dependent on intra-oocyte calcium release. The present article reviews the current knowledge on the biogenesis and molecular composition of sperm PT. Possible functions of sperm PT during natural and assisted fertilization, and in the initiation of embryonic development are discussed. Furthermore, evidence is provided that SOAF is transferred from the sperm PT to oocyte cytoplasm through the internalization and rapid solubilization of the post-acrosomal PT. It is shown that during natural fertilization the sperm PT dissolves in the oocyte cytoplasm concomitantly with sperm nuclear decondensation and the initiation of pronuclear development. SOAF activity is preserved in the differentially extracted sperm heads only if the integrity of PT is maintained. After intracytoplasmic sperm injection (ICSI), activation occurs only in those oocytes in which the injected spermatozoon displays complete or partial dissolution of PT. In the latter case, the residual PT of the sub-acrosomal and/or post-acrosomal sperm region may persist on the apical surface of the sperm nucleus/male pronucleus and may cause a delay or arrest of zygotic development. We propose that the sperm PT harbors SOAF in the post-acrosomal sheath, as this is the first part of the sperm cytosol to enter the oocyte cytoplasm and its disassembly appears sufficient to initiate the early events of oocyte activation. Dissolution of the sub-acrosomal part of the PT, on the other hand, appears necessary to insure complete DNA decondensation in the internalized sperm nucleus and initiate DNA synthesis of both pronuclei. The release of the SOAF from the sperm head into oocyte cytoplasm at fertilization ultimately leads to the activation of oocyte mechanism including the completion of the meiotic cell cycle, pronuclear development and anti-polyspermy defense.     

Morphology of mammalian sperm membranes during differentiation,maturation, and capacitation

The mammalian spermatozoon is a highly polarized cell whose surface membrane can be divided into five functionally, structurally, and biochemically distinct domains. These domains are formed during spermatogenesis, continue to be modified during passage through the epididymis, and are further refined in the female reproductive tract. The integrity of these domains appears to be necessary for the sperm to perform its function—fusion with the egg and subsequent fertilization. The domains can be identified morphologically by their surface contours and texture, the content, distribution, and organization of intramembranous particles after freeze-fracture, and by the density of surface and cytoplasmic electron-dense coatings in thin sections. By using a variety of labels that stain carbohydrates (lectins), lipids (filipin and polymyxin B), and monoclonal antibodies to specific membrane constituents, the biochemical composition of these contiguous membrane regions has also been partly elucidated. We review here what is known about the structure, composition, and behavior of each membrane domain in the mature sperm and include some information regarding domain formation during spermatogenesis. The sperm is an excellent model system to study the creation and maintenance of cell polarity, granule exocytosis, and fertilization. Hopefully this review will provide impetus for future studies aimed more directly at addressing the relationship of its morphology to its functions.     

基矛NIOS Ⅱ的数据采集系统

NIOS Ⅱ是Altera公司推出的第二代IP软核处理器,它与其他IP核构成了SOPC系统的主要部分。用户可以通过自定义逻辑的方法在SOPC设计中添加自己开发的IP核,使设计简单高效。本文利用FPGA中内嵌的NIOS Ⅱ处理器设计了一种数据采集系统。通过FPGA内部自带的双口RAM IP核和乒乓操作,实现数据的缓存。利用NIOS Ⅱ嵌入式软核实现缓存数据的读取、存储和传输。缓存数据的读取采用自定义组件的方式实现。该系统避免了控制单元与时序单元的分立设计,简化了电路,增强了可靠性,具有较好的可移植性。经试验验证,该系统能够较好地实现数据的采集,运行效果良好。     

金属结合硫蛋白在TRIS-醋酸缓冲

金属硫蛋白（metallothionein,&n     

Elman神经网络的红外地球敏感器实时故障诊断

以卫星姿控系统实时仿真信号为诊断依据,设计故障检测Elman神经网络及故障判决,实现系统正常与非正常状态的区分并获取故障发生时刻。提出了基于改进梯度更新策略的故障隔离Elman神经网络方法,对故障时刻点之后时域信号进行故障模式匹配,进一步实现系统故障隔离。运用某卫星姿态控制系统进行在线故障诊断试验的结果表明,本文方法具有较好的实时有效性、输出耦合诊断性能、时域信号诊断泛化性和网络收敛性。     

多孔层的孔隙特性和各向异性对燃料电池瞬态性能的影响

燃料电池(Fuelcell,FC)与外部环境之间的传热和多孔层的传质均会影响FC内的水热气电状态,进而影响到催化层的电化学反应速率,从而显著影响其瞬态性能(Transient performance,TSP)。多孔层的孔隙特性和各向异性是影响其传热传质能力的关键因素,充分认识其对FC-TSP的影响规律,对于优化车载FC动力源的负载响应有重要意义。为此,综合考虑FC与外部环境动态热交换,内部水热气电等各物理性质的空间动态分布以及气、液和溶解相等多相时变转化关系,建立FC多相三维瞬态传质传热数值模型,以分析多孔层非均质性质对动态过程的影响。进一步,以电流密度的阶跃变化模拟动态负载,分析FC的电压,膜的水含量和温度,微孔层|催化层界面的氧浓度。结果表明,多孔层的孔径大小和分布及各向异性对FC的TSP有明显影响。另外,不同热条件对FC的内部物理量分布的影响较对TSP的影响更为显著。     

Telnet在8位机上的实现

嵌入式系统与以太网互联是近几年来的一个热点。由于16位和32位机的资源相对丰富,上网方案相对成熟,都是基于大内存容量的协议栈。但是,在8位低端处理器上网方案中,要移植这些协议栈就不太现实。本文讨论了uIP协议栈在8位机上的应用,并且成功建立了一个稳定的网络Telnet服务器,实现了对系统的远程监控。     

Heads you win,tails you lose: filtration processing for the microscopical examination of sperm heads

The sperm head plays a key role in many fertilisation events and determining the precise location of molecules within the head region is important in mechanistically dissecting the fertilisation process. Such molecules may be present in low copy number and many sperm head profiles must be examined to localise them to particular subcellular structures with confidence. Filtration has traditionally been used for the purpose of concentrating biological material, such as free‐living cells, spores, and subcellular fractions, and little attempt has been made to extend the procedure to encompass the entire processing schedule, mainly due to the incompatibility of intermediate dehydrating solvents with membrane filters. The novel and simple technique of filtration processing that we describe produced a dense mat of cells, with several sperm heads being visible in coronal orientation in a high‐power field at the light microscopic level, and allowed positive immunocytochemical staining to be identified with confidence. This new technique exploits the low viscosity of LR White acrylic resin to allow the entire processing procedure to be undertaken in the filtration apparatus. In contrast, conventional techniques for preparing free‐living cells, namely pre‐embedding in a supportive matrix prior to processing, and centrifugation at each stage of the processing procedure, proved suboptimal, partly due to the final concentration that could be achieved, but mainly due to the random orientation of cells that these techniques afforded.     

Structure, heterologous expression, and adhesive properties of the P(0)-like myelin glycoprotein IP1 of trout CNS

The IP1 protein of trout CNS myelin as well as an IP1/P(0) chimeric protein were stably expressed in CHO cells. Successful targeting of the recombinant proteins to the membrane surface was verified by immunofluorescence staining. Full-length expression of IP1 could be confirmed by Western blot analysis of proteins extracted from stably transfected CHO-cells. The adhesive properties of IP1 were studied by an in vitro aggregation assay in which microscopic examination was combined with electronic particle counting. While IP1 conveyed only a weak increase in cell aggregation of transfected CHO cells, the IP1/P0 chimera was much more effective. In the presence of specific antibodies, cell aggregation was strongly reduced. The adhesive properties of P(0)-like proteins are discussed considering recent crystallographic data on the atomic structure of the extracellular domain of mammalian P(0).     

Seasonal variations in the heterologous binding of viscacha spermatozoa. A scanning electron microscope study.

Seasonal changes in the reproductive activity of the adult male viscacha (Lagostomus maximus maximus) were investigated during the annual reproductive cycle. Assays of heterologous in vitro binding between compatible gametes were used to evaluate the ability of viscacha spermatozoa to achieve primary binding during its annual reproductive cycle. Sperm were collected by mincing cauda epididymis in HECM-3 medium and the sperm concentration and motility were evaluated. Cumulus-free and zona-free oocytes obtained from superovulated hamsters were inseminated in vitro with capacitated sperm suspensions, incubated at 37 degrees C, 5% CO2 for 3 h, and then processed for studies by scanning electronic microscopy. Statistical analysis was used to compare the quantitative differences. The number of spermatozoa significantly decreases during the regression period, while sperm motility was progressive speed in both periods. During the active period elevated sperm binding to cumulus-free and zona-free oocytes was observed, while the binding during the regression period decreased drastically. In both periods, oocyte microvilli covered sperm heads and tails. These results suggest that the ability of viscacha spermatozoa to participate in gamete recognition is profoundly affected. This would likely be related to different functional stages of the spermatozoa and their epididymal microenvironment during the annual reproductive cycle of viscacha.     

空冷器板翅式传热元件翅片高度的优化计算

为了探究板翅式传热元件翅片高度对传热、压降的影响,以某装置冷却项目为工程实例,采用板翅式空冷器进行设计,应用数学解析方法,经计算比较,翅片高度为14 mm时,单台设备的传热系数与换热面积的乘积达到最大,节省投资;翅片高度为22 mm时,单台设备的空气侧单位压降的总传热系数最大,操作费用较低。翅片高度的选取需综合考虑初期设备投资和后期操作费用的关系。     

Invited article: millimeter-wave bolometer array receiver for the Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument

The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the Sunyaev-Zel'dovich effect from the 12 m APEX telescope on the Atacama plateau in Chile. The receiver contains a focal plane of 280 superconducting transition-edge sensor (TES) bolometers instrumented with a frequency-domain multiplexed readout system. The bolometers are cooled to 280 mK via a three-stage helium sorption refrigerator and a mechanical pulse-tube cooler. Three warm mirrors, two 4 K lenses, and a horn array couple the TES bolometers to the telescope. APEX-SZ observes in a single frequency band at 150 GHz with 1' angular resolution and a 22' field-of-view, all well suited for cluster mapping. The APEX-SZ receiver has played a key role in the introduction of several new technologies including TES bolometers, the frequency-domain multiplexed readout, and the use of a pulse-tube cooler with bolometers. As a result of these new technologies, the instrument has a higher instantaneous sensitivity and covers a larger field-of-view than earlier generations of Sunyaev-Zel'dovich instruments. The TES bolometers have a median sensitivity of 890 μK(CMB)√s (NEy of 3.5 × 10(-4) √s). We have also demonstrated upgraded detectors with improved sensitivity of 530 μK(CMB)√s (NEy of 2.2 × 10(-4) √s). Since its commissioning in April 2007, APEX-SZ has been used to map 48 clusters. We describe the design of the receiver and its performance when installed on the APEX telescope.     

Impacts of inflow conditions on the measurement stability of a turbulence-mitigation based liquid concentration detection system

Liquid concentration plays an important role in many industrial processes. We designed a concentration detection system based on the principle of differential pressure, and introduced a turbulence elimination structure (TES) to improve the internal flow field. In order to explore the influence mechanism of the internal flow field on the detection, two models were used for numerical simulation under different working conditions. The results show that TES can effectively restrain the velocity fluctuation and turbulence intensity change of the flow field in the observation trough, thus forming a good measurement environment. The experimental results show that the measurement signal of the model with TES is more stable, and a stable detection area is formed between sensor 1 and sensor 3, which can be used for efficient detection of the sensor system. For the model with TES, the optimal speed range of 0.3–0.8 m/s was determined through experiments.     

A hip joint simulator study using new and physiologically scratched femoral heads with ultra-high molecular weight polyethylene acetabular cups

This study validates a hip joint simulator configuration as compared with other machines and clinical wear rates using smooth metal and ceramic femoral heads and ultra-high molecular weight polyethylene (UHMWPE) acetabular cups. Secondly the wear rate of UHMWPE cups is measured in the simulator with deliberately scratched cobalt-chrome heads to represent the type of mild and severe scratch damage found on retrieved heads. Finally, the scratching processes are described and the resulting scratches compared with those found in retrieved cobalt-chrome heads. For smooth cobalt-chrome and zirconia heads the wear rates were found to be statistically similar to other simulator machines and within the normal range found from clinical studies. An increased wear rate was found with cobalt-chrome heads scratched using either the diamond stylus or the bead cobalt-chrome but the greatest increase was with the diamond scratched heads which generated scratches of similar dimensions to those on retrieved heads. A greater than twofold increase in wear rate is reported for these heads when compared with smooth heads. This increased wear rate is, however, still within the limits of data from clinical wear studies.     

Gamete interactions and the fate of sperm organelles in fertilized echinoderm eggs

Investigations of gamete fusion, sperm entry and the fate of the sperm nucleus, plasma membrane, mitochondrion, and axonemal complex in fertilized echinoderm eggs are reviewed. The timing of gamete fusion with respect to the onset of electrical activity characteristic of the activated egg and the affects of fixation conditions on the stability of fusing membranes are discussed. Observations from investigations using cationized ferritin labeled gametes and immunogold cytochemistry to demonstrate the mixing of sperm plasma membrane components within the egg plasma membrane, in particular along the surface of the fertilization cone, are compared with results from studies in somatic cells. Transformations of the sperm nucleus into a male pronucleus, consisting of sperm nuclear envelope breakdown, chromatin dispersion, and formation of a pronuclear envelope, are correlated with recent biochemical observation of similar processes in other cellular systems. Fates of the sperm mitochondrion and axonemal complex are examined.     

Improved preservation of the ram spermatozoan plasma membrane using betaine in the primary fixative

Improved preservation of ram spermatozoa was obtained by filtration onto a Millipore filter followed by fixation in a fixative containing 23 m m betaine, which raised fixative osmolality only slightly. In samples fixed in control preparations with betaine omitted the plasma membrane had a ruffled appearance, while the betaine-containing fixative gave the plasma membrane a smooth contour which closely followed underlying structures.
Betaine is known to function as an osmoprotectant in other situations, and may protect the cells from osmotic damage during the initial stages of fixation.