移动式多级分离计量装置方案设计

针对油田传统的计量方式不能满足油田生产测试过程中各井的产量测试,特别是几乎不可能同步测试、记录功图测试阶段的产油气量,难以在较宽的计量范围内实现精确计量要求的现状,设计了移动式多级分离计量装置的方案.介绍了移动式多级分离计量装置的结构、原理、主要技术指标、系统的组成、技术关键和需要在设计中重点考虑的几个问题.着重阐述了设计过程中在以往的技术和经验的基础上开发和采用了高效气-液旋流分离技术、高效多级液-液旋流分离技术、破乳技术、多次沉降分离提高纯油计量精度技术、计量分离器的排液技术和最佳流量计的选择标准等几项关键技术,并对如何破除混合液中的乳化水以增强分离效果,以及在串联旋流器时应重点考虑以底流还是溢流为主的参数控制方式等问题做了研究.     

Degenerative process and cell death in salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged female exposed to the acaricide permethrin

Ticks are ectoparasites of great medical and veterinary importance around the world and synthetic chemicals such as permethrin have been used for their control. This study provides a cytochemistry analysis of both degenerative and cell death processes in salivary glands of the brown dog tick Rhipicephalus sanguineus semi-engorged females exposed to 206, 1,031, and 2,062 ppm of permethrin. The results presented herein demonstrate that permethrin is a potent chemical acaricide that would act on the glandular tissue's morphophysiology in this tick species by eliciting severe changes in the acinus shape, intense vacuolation of the acinar cells' cytoplasm, marked glandular tissue disorganization, culminating in an advanced degenerative stage with consequent formation of many apoptotic bodies (cell death). In addition, permethrin induced major changes in the acinar cells' nucleus, such as a change both in its shape and size, chromatin marginalization, nuclear fragmentation, and appearance of picnotic nuclei, especially when the highest concentrations of the product were used. Thus, permethrin induced early degeneration of this tissue characterized by significant changes in the structure of acinar cells and production of enzymes related to the cell death process, in addition to interfering directly in the genetic material of these cells.     

工业机器人轨迹规划研究现状综述

凭借良好的环境适应性、高效率、高生产质量以及7×24工作模式,工业机器人广泛地应用于喷涂、焊接、码垛、搬运等自动化生产中.轨迹规划是工业机器人完成作业任务运动控制的基础,直接决定了机器人工作质量.为了全面了解轨迹规划现有研究方法,首先阐述了轨迹规划的基本流程,根据轨迹规划的原理不同对现有轨迹规划方法进行了分类,并分别对各种插补曲线函数、最优轨迹规划以及求解算法的性能特点进行了详细的分析与总结.最后对轨迹规划在插补曲线构造和求解算法方面的现存问题做出了分析和讨论,并展望了轨迹规划的发展趋势.     

Oestrogen's masculine side: mediation of mating in male mice

This review focuses on the role of oestrogen in male sexual behaviour using oestrogen receptor alpha and beta knockout (ERalphaKO and ERbetaKO) mouse models. ERbetaKO mice are capable of mating and producing offspring, whereas ERalphaKO mice are unable to do either. When ERalphaKO males are treated with testosterone or dihydrotestosterone (DHT), < 50% display mounting behaviour, few intromit and none ejaculate. However, concurrent treatment with testosterone and a dopamine agonist instates masculine sexual behaviour in both male and female ERalphaKO mice. Dopamine content in the preoptic area and associated regions is not affected by oestrogen receptor alpha gene disruption. However, expression of neuronal nitric oxide synthase immunoreactivity is severely reduced in ERalphaKO males compared with wild-type males. These findings, together with studies conducted in aromatase knockout mice, are at odds with the dogma that oestrogen is required during development for expression of male sexual behaviour in adults. However, they do support a role for oestrogens, mediated by oestrogen receptor alpha, in regulation and production of neuronal nitric oxide synthase, which in turn may control dopamine agonist release. As has been shown in male rats, in mice dopamine agonist release is likely to be an essential component of the neural pathway that mediates male sexual behaviour.     

Partial replacement of forage with nonforage fiber sources in lactating cow diets. I. Performance and health

Seventy-eight Holsteins were fed for 112 d to evaluate performance and health responses to diets varying in source and concentration of fiber. Three diets based on different carbohydrate feeding strategies were formulated. These diets contained low concentrations of forage and neutral detergent fiber (NDF) (12.6% forage NDF, 19.5% total NDF), adequate NDF and forage (20% forage NDF, 24.8% total NDF), or low forage with additional NDF from cereal byproducts (12.7% forage NDF, 33.4% total NDF). Responses to sodium bicarbonate supplementation (0 or 0.8% of diet DM) were evaluated for each carbohydrate strategy, and bicarbonate improved performance on all diets. Eight cows were used concurrently in a Latin square experiment to evaluate the linearity of milk fat concentration response to increasing concentrations of byproduct NDF in low-forage diets. Considering both trials, cereal byproduct NDF was only 27% as effective as NDF from alfalfa silage in eliciting a milk fat concentration response, which was less than predicted from previous experiments. This difference was not because of the short duration of previous experiments nor because of nonlinearity in the response to byproduct NDF. Low-forage diets fed for 112 d did not result in major health disorders for midlactation cows. However, several indicators suggested that cows fed low-forage, high-NDF diets might be less susceptible to ruminal acidosis than those fed diets containing low forage and low NDF, especially during times of dietary transition. Although the effective fiber value in various feeds is variable and difficult to quantify, the value of byproduct fiber needs to be considered when balancing the carbohydrate fraction of dairy rations.     

Elastic laser light scattering by GaAs surfaces

Angle-resolved scattering (ARS) intensities were measured in the backscattering hemisphere for the (1 0 0) and (1 1 1) faces of GaAs single crystals. Three epitaxial layers were deposited onto the GaAs (1 0 0) single-crystalline wafers. The laser elastic light scattering shows the presence of a regular surface microrelief whose orientation corresponds to the crystallographic axes in the surface plane. We studied the statistical properties of this microrelief and determined the parameters that characterize the surface. We propose to use the ARS ratio for two wavelengths (in our case, 632.8 and 441.6 nm) to determine the topographical properties of scattering and to study crystal surface defects.     

Effect of inoculum size, relative humidity, storage temperature, and ripening stage on the attachment of Salmonella Montevideo to tomatoes and tomatillos

The influence of inoculum populations and environmental factors on attachment of Salmonella Montevideo to the surface of tomatoes and tomatillos was evaluated. To study the effect of inoculum size, red, ripe tomatoes were spot-inoculated with bacterial suspensions (10(5) and 10(8) CFU/fruit) and stored at 22 degrees C under 100% relative humidity. The effects of temperature (12, 22, and 30 degrees C) and relative humidity (75, 85, and 97%) on attachment of the pathogen (10(7) CFU/fruit) to tomatoes (red and green) and ripe tomatillos were also evaluated. Inoculated fruits were stored for 90 min at all combinations of temperature and relative humidity, and after rinsing with water, the number of cells attached to the surface was determined. Salmonella Montevideo attached to the surface of tomatoes within 90 min. A direct correlation between the number of attached cells and the population in the inoculum was observed. The percentage of cells that attached immediately after inoculation was approximately 0.3% for the three test products. After storage for 90 min at various temperature and relative humidity conditions, the number of adhering cells ranged from 4.0 to 5.4 log CFU/fruit (1.2% of inoculum). Both the type of product and the temperature/relative humidity combination had a significant (P < 0.05) effect on attachment of Salmonella Montevideo to the surfaces of tomatoes and tomatillos. Scanning electron micrographs of the cuticles of inoculated washed tomatoes and tomatillos revealed typical skin cell patterns, and only a few randomly dispersed Salmonella Montevideo were observed. Deposition of Salmonella Montevideo on the surface of tomatoes and tomatillos could result in attachment and subsequent colonization under suitable conditions.     

Effects of (+/-)-idazoxan alone and in combination with L-DOPA methyl ester in MPTP-induced hemiparkinsonian monkeys

The effects of a combination of the alpha2-adrenergic receptor antagonist (+/-)-idazoxan with L-DOPA methyl ester were examined in three of four female adult monkeys (Macaca nemestrina) rendered hemiparkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). (+/-)-Idazoxan (0.16, 0.63, and 1.0 mg/kg) was given i.m. 10 min before L-DOPA methyl ester (12.5 mg/kg). (+/-)-Idazoxan reduced the maximum peak of contralateral circling elicited during the first hour following injection of L-DOPA methyl ester, but prolonged the duration of the circling response up to 50% (p < 0.05). The data support a role for alpha2-adrenergic receptor mechanisms in modulating the effects of L-DOPA on nigrostriatal dopamine function in the MPTP monkey model of hemiparkinsonism.     

Optical tests of nanoengineered liquid mirrors

We describe a new technology for the fabrication of inexpensive high-quality mirrors. We begin by chemically producing a large number of metallic nanoparticles coated with organic ligands. The partides are then spread on a liquid substrate where they self-assemble to give optical quality reflective surfaces. Since liquid surface can be modified by a variety of means (e.g., rotation, electromagnetic fields), this opens the possibility of making a new class of versatile and inexpensive optical elements that can have complex shapes and that can be modified within short time scales. Interferommetric measurements show optical quality surfaces. We have obtained reflectivity curves that show 80% peak reflectivities. We are confident that we can improve the reflectivity curves because theoretical models predict higher values. We expect nanoengineered liquid mirrors to be useful for scientific and engineering applications. The technology is interesting for large optics, such as large rotating parabolic mirrors, because of its low cost. Furthermore, because the surfaces of of ferrofluids can be shaped with magnetic fields, one can generate complex, time-varying surfaces that are difficult to make with conventional techniques.