波德代公羊繁殖性能的季节变化

以从新西兰首次引入的波德代成年公羊为研究对象 ,对其繁殖性能进行了为期一年的试验研究。结果表明 ,波德代羊射精量 (mL)在 11月份最高 (1 81) ,5月份最低 (1 2 9) ;秋季低 (1 4 1) ,冬季高 (1 6 1)。原精活率最低值和最高值分别出现在 5月份 (0 70 )和 1月份 (0 79) ,夏季较低 (0 70 ) ,冬季较高 (0 77) ;最低、最高原精密度 (亿个 /mL)分别在 5月份 (2 7 2 0 )和 3月份 (42 6 0 ) ;冬季密度高 (40 37) ,夏季密度低 (35 5 7)。畸形率在 10月份最低 (8 94 % ) ,5月份最高 (18 0 5 % ) ;春季高(14 99% ) ,秋季低 (10 4 6 % )。冻精解冻活率最高值都在 9月份 ,最低值在 5月份。春季制作的冻精解冻活率低 ,秋季制作的冻精解冻活率则较高 ;性反应时间最高值都出现在春季。精清中睾酮含量(pg/mL)最高、最低值分别在 8月份 (2 2 17 7)和 10月份 (331 2 ) ;夏季低 (45 1 6 ) ,冬季高 (15 10 3)。

人手指柔性触觉感知的记忆特性

触觉再现技术是当前虚拟现实和远程操作机器人领域的前沿,而柔性触觉则是其重要的研究内容。触觉再现接口的设计需要充分研究人手的触觉感知特性。本文在柔性触觉装置上研究了人手指柔性触觉记忆特性。先通过回忆性实验确定人手指的柔性触觉记忆容量,在记忆容量范围内又进行了再认性实验,对人手指的柔性触觉记忆反应时间进行分析。本实验方法简单有效,得出的结论不仅可以用来改进触觉再现装置的设计,而且为触觉再现技术的研究提供了生理学依据。

Effects of acute aerobic exercise on response preparation in a Go/No Go Task in children with ADHD:An ERP study

Purpose： The purpose of this study was to investigate the impact of acute exercise on reaction time and response preparation during a Go/No Go Task in children with attention deficit hyperactivity disorder （ADHD）. Methods： Nineteen children with ADHD （aged between 8 and 12 years old） undertook a 30-min intervention that consisted of treadmill running or video-watching presented in a counterbalanced order on different days. A Go/No Go Task was administrated after exercise or video-watching. Results： The results indicated a shorter reaction time and smaller contingent negative variation （CNV） 2 amplitude following exercise relative to the video-watching. For event related potential （ERP） analyses, greater CNV l and CNV 2 amplitudes in response to No Go stimuli in com- parison to Go stimuli was observed in the video-watching session only. Conclusion： These findings suggest that acute exercise may benefit children with ADHD by developing appropriate response preparation, particularly in maintaining a stable motor preparatory set prior to performing the given task.

Catalytic synthesis of perfluorolyethers

Perfluorolyether is characterized by highly chemical inertness, oxidative stability, anticorrosion as well as radiation resistance. It can be used as lubricant especially in harsh environmental conditions. In this work, hexafluoropylene oxide was catalytically polymerized at low temperature using the methods of anionic polymerization, and perfluorolyethers were obtained with number-average degree of polymerization more than 15. CsF and RbF were used as catalysts and their catalytic activities were investigated. Experimental results show that perfluorolyethers with number-average molar masses up to 3 000 g/mol could be obtained using the two kinds of catalysts, respectively. As compared to CsF, the number-average degree of polymerization is higher and the relative molecular mass distribution interval is narrower when RbF is used as catalyst. The effect of factors such as impurities＇ content, reaction temperature and reaction time on the number-average degree of polymerization was also investigated. It is found that low impurities＇ content and low temperature are beneficial to the generation of high number-average degree of perfluorolyethers. The optimization reaction time is 24 h, and fiarther increase of reaction time does not significantly affect the average relative molecular mass. The product was characterized by IR, 19F NMR and GC-MS, and the catalytic mechanism was analyzed finally.

An 8-week reactive balance training program in older healthy adults： A preliminary investigation

Background： This preliminary study examined the effects of an 8-week supervised reactive balance training program on reaction time （RT） and foot speed, static balance and balance confidence in healthy older adults compared to an exercise control group. Methods： Twenty-five older adults were randomly assigned to a reactive balance training group （QuickBoard; n = 12; 71.0 ± 8.6 years） or a stationary cycling group （control; n = 13; 70.2 ± 6.0 years）. Both groups were tested for foot RT foot speed, static balance, and balance confidence at baseline, 4-week, 8-week, and 4-week follow-up. Results： Results indicated significant improvements in QuickBoard foot RT and speed in both groups with greater improvements in the QuickBoard group. However, no group difference was found in static balance performance. Conclusion： Although the improvements in RT and foot speed may be beneficial for fall and trip prevention, the implications of the current findings for trio avoidance and oerformance of daily tasks are unclear.

Silver Nanoparticles Synthesized by Laser Ablation in Acetone： Influence of Ablation Time and Their Reactivity with Oxygen in the Air

In this work, a method is proposed to control silver nanoparticle dimensions produced by laser ablation varying the ablation time and introducing a sonication phase between ablation and the successive deposition on the substrate. The absorption spectra during laser ablation show a main band, which identifies the dimensions of main particles. The appearance of secondary bands indicates the beginning of an aggregation process with the formation of a small concentration of particles which are spheroid in shape. SEM （secondary electron microscope） images of particle produced with different ablation times confirm the results of absorption measurements. X-ray photoelectron spectroscopy and cathodo-luminescence spectroscopy indicate a high reactivity of the nanoparticles deposited on a substrate. They react with oxygen in the air forming an oxide layer which reveals a luminescence in the blue region.

DMAc used as a reducer for preparation of spherical silver nanoparticles with high dispersion

A silver nanoparticle(Ag NP) with good monodispersity was produced by a convenient method for reducing of Ag NO3 with N, N-dimethylacetamide in the presence of polyvinyl pyrrolidone(PVP) as the surface modification agent. The shape and size of the Ag NP with reaction time were taken as variables. The surface plasmon band transition was monitored with reaction mixture time at different temperatures. The Ag NP crystallinity increases with the reaction time, and the reduction efficiency is very low when Ag NP solution is dealt at room temperature even after two days, while it is greatly improved at 160 °C only for 25 min. Ag NP modified by the as-synthesized PVP has a face-centered cubic crystalline structure, in which Ag NP could develop into a spherical morphology with a very narrow size distribution of 2-11 nm. The preparation provides a new reducing agent to form Ag NP with simpler operation and shorter time.

Airborne Pollen Grains Of Afyon, Turkey

The airborne pollen grains of Afyon have been studied for a two_year period (1999-2000) with a Durham sampler. A total of 14 367 pollen grains belonging to 40 taxa have been identified and recorded with some unidentified ones. Of them, 6 732 were identified in 1999 and 7 635 in 2000. Of the total pollen grains, 69.67% were arboreal, 26.64% non_arboreal and 3.68 % unidentified. The majority of the investigated pollen grains were from Pinus, Gramineae, Cupressaceae, Platanus , Chenopodiaceae/Amaranthaceae, Quercus, Ailanthus, Moraceae, Juglans , Salix, Cedrus and Rosaceae. The highest level of pollen grains was in May.

Where are the limits of the effects of exercise intensity on cognitive control?

Purpose： This study aimed to investigate whether workload intensity modulates exercise-induced effect on reaction time （RT） performances, and more specifically to clarify whether cognitive control that plays a crucial role in rapid decision making is altered. Methods： Fourteen participants performed a Simon Task while cycling 20 min at a light （first ventilatory threshold, VT~ - 20%）, moderate （VTI）, or very hard （VTj ＋ 20%） level of exercise. Results： After 15 min of cycling, RTs are faster than during the first 5 min of exercise. This benefit does not fluctuate with the intensity of exercise and enlarges as RT lengthens. Despite a numerical difference suggesting a greater facilitation during moderate exercise （-16 ms） than during a light exercise （-10 ms）, the benefit is not statistically different. Interestingly, we did not observe any signs of worsening on RT or on accuracy during very hard exercise. Conclusion： Cognitive control is extremely robust and appears not to be affected by the intensity of exercise. The selective inhibition and the between-trials adjustments are effective from the beginning to the end of exercise, regardless of the workload output.

Characteristics of gas explosion flow fields in complex pipelines

The explosion flow field in five straight pipes with different diameters and one bending pipe selected from a domestic coal mine are studied by the method of numerical simulation. And the results show that,both in the straight and bending pipes, the pressure wave and velocity wave are accelerated by the rising of reaction rate. As the explosion progressed, with the temperature reaching approximately 3000 K, only one pressure wave and one reaction rate wave were observed, while several velocity waves were found.The larger diameter presented the highest relative pressure as well as the largest velocity increase and subsequent decrease inside the tube. The bent pipes caused both turbulence and kinetic energy to increase, resulting in the acceleration of the reaction rate. The burning time was 7.4% shorter than the burning time observed for the straight pipe. Based on these results, designing one explosion resistance device, and in the practical engineering applications, it was to be proved to meet the security requirements fully.

TanDEM-X Autonomous Formation Flying System： Flight Results

The TanDEM-X mission is a scientific and commercial Earth observation mission comprising two satellites flying in close formation. The formation maintenance can be advantageously performed by an onboard autonomous system, which reduces the operational efforts, provides a shorter reaction time in case of contingencies and increases the control performance. The TanDEM-X Autonomous Formation Flying （TAFF） system has been developed for this purpose and is intended to replace the ground-based formation keeping activities during routine operations. TAFF has been activated for the first time in October 2010 for commissioning, during which the autonomous usage of thrusters was prohibited. Afterwards, a closed-loop campaign was successfully conducted in March 2011, demonstrating the capability of TAFF to maintain autonomously the formation. After a brief technical description of the system, the paper presents the key results gained during the commissioning phase and the closed-loop campaign,

Kinetic Dependences of Two-Stage Dilute Acid and Enzyme Hydrolysis of Paulownia tomentosa

The sugars potential ofPaulownia tomentosa is estimated by dilute acid pretreatment and cellulase hydrolysis. The kinetics of dilute （1%） sulfuric acid hydrolysis is studied at temperatures of 100 ℃, 120 ℃ and 130 ℃, while the kinetics of the subsequent enzyme hydrolysis is examined at a temperature of 50 ℃ and reaction time varied from 60 to 300 min using cellulase complex NS 50013 and β-glucosidase N S 50010. The reducing sugars formation is modeled as a pseudo-homogeneous first order reaction in view of the kinetics of dilute sulfuric acid hydrolysis. The results obtained indicate that the reaction proceeds in an energetically homogeneous system （E = const） providing identical accessibility of the reagent to the hydrolyzing sites （A = const）. The enzyme hydrolysis kinetics follows heterogeneous catalytic mechanism. The process is described by an exponential kinetic equation, which is well recognised in case of processes on uniformly inhomogeneous surfaces. The current rate decreases significantly probably because of exhaustion of the available active sites on the surface and steric hindrances due to the presence of lignin. This investigation provides information of importance for the fermentation step of the bio-ethanol production process.

Observation of mitochondrial activity based on temporal and spatial pH variations measured by near-field fluorescent ratiometry

A novel method combining dual wavelength fluorescent ratiometry with scanning near-field optical microscopy (SNOM) is proposed and developed to measure the concentration and distribution of protons in the vicinity of biological samples. This method involves immersing mitochondria in a pH-sensitive fluorescent dye solution instead of injecting the dye into the surface of the mitochondrial membrane. It uses a dual emission pH-sensitive dye and SNOM with a thermally pulled and metal-coated optical fiber probe to improve the spatial resolution. The time dependence of the fluorescence intensity ratio (FIR) under acid addition and the response of mitochondria to nutritional supplementation were studied by using this method. Activation of mitochondria and a distance-dependent delay in the FIR response were observed. The results confirmed that mitochondrial activity could be observed by using this method.

Application of Kinetic Models in Describing Soil Potassium Release Characteristics and Their Correlations with Potassium Extracted by Chemical Methods

Potassium （K） release characteristics in soil play a significant role in supplying available K. Information on K-release characteristics in soils of central Iran is limited. The objectives of this study were to determine K release characteristics and correlations of K release rate constants with K extracted by different chemical methods in surface soils of ten calcareous soils of central Iran. The kinetics of K release in the soils was determined by successive extraction with 0.01 mol L-1 CaC12 in a period of 2-2017 h at 25±1℃. Soil K was extracted by distilled water, 0.5 mol L-1 MgNO3, 0.002 mol L-1 SrC12, 0.1 mol L-1 BaC12, 0.01 mol L-1 CaC12, 1 mol L-1 NaC1, 1 mol L-1 boiling HNO3, 1 mol L-1 NH4OAC, Mehlich 1, 0.002 mol L-1 SrC12 ＋ 0.05 mol L-1 citric acid, and ammonium bicarbonate-diethylenetriamine pentaacetic acid （AB-DTPA）. A plot of cumulative amounts of K released showed a discontinuity in slope at 168 h. Thus, two equations were applied to two segments of the total reaction time （2-168 and 168-2 017 h）. Cumulative amounts of K released ranged from 55 to 299 mg kg-1 in 2-168 h and from 44 to 119 mg kg-1 in 168-2 017 h. Release kinetics of K in the two time segments conformed fairly well to parabolic diffusion, simplified Elovich, and power function models. There was a wide variation in the K release rate constants. Increasingly higher average concentrations of soil K were extracted by distilled water, Mehlich 1, SrC12, CaC12, SrC12 ＋ citric acid, AB-DTPA, MgNO3, NaCI, NH4OAc, BaCI2, and HNO3. Potassium release rate constants were significantly correlated with K extracted. The results of this study showed that information obtained from mathematical modeling in two reaction time segments can help to estimate the K-supplying power of soils.

B cells biology in systemic lupus erythematosus—from bench to bedside

Systemic lupus erythematosus(SLE) is a debilitating autoimmune disease that can involve multi-organs. B cells play a central role in the immunopathogenesis via antibody-dependent and antibody-independent ways. Excessive autoantibodies production, hyperresponsiveness and prolonged survival of autoreactive B cells are characteristics of SLE. In this article, mechanisms of self-tolerance loss of B cells and promising B cell-targeting therapies in lupus are reviewed and discussed.

Do females influence paternal responsiveness in male prairie voles Microtus ochrogaster by increasing the salience of infant odors？

Male prairie voles become more responsive to infants following cohabitation with a female. Exposure to female sen- sory cues prior to offspring birth may influence male paternal tendencies by modifying his response to infant odors in particular or to odors in general. To test these hypotheses, males were housed with an unfamiliar female or a same-sex sibling for 13 days then examined for their response towards either live infants or infant-like inanimate objects covered with one of three odors： wa- ter, infant, sub-adult. We recorded the number of males that retrieved and manipulated the infants or odor-covered objects and measured the frequency and duration of time males spent attending to them or engaged in other non-social activities. Fe- male-Cohabited males approached the container holding infant-odor covered objects faster than Male-Cohabited males, but showed no differences in time spent manipulating those objects. Males in both groups spent more time manipulating live infants than odor-covered objects. However, Female-Cohabited subjects were more likely to manipulate odor-covered objects as well as live infants than Male-Cohabited subjects. Additionally, the frequency of self-grooming in Female-Cohabited males was higher for water-covered objects compared to Male-Cohabited males. In presence of water and live infants, Female-Cohabited males groomed themselves with greater frequency than in presence of infant odor or sub-adult odor. The data suggest that female cues increase the male＇s sensitivity to infant odors and enhance the salience of non-social odors.

Formation of time patterns in a diffusive plant-herbivore system with toxin-determined functional response

In this paper, we consider a diffusive plant-herbivore system with the toxin-determined functional response and subject to the homogeneous Neumann boundary conditions on the bounded one-dimensional spatial domain. The impacts of diffusion on the dynamical behaviors are investigated and it is found that although the appearance of diffusion does not affect the stability of constant steady states, it can lead to the occurrence of Hopf bifurcation of spatially inhomogeneous periodic solutions at the constant positive steady state. The conclusions show that the occurrence of spatial diffusion can induce more complex dynamical behaviors.