微量气体大小球三步同位素稀释质谱法理论探讨与实验模型设计

提出了一种适用于微量气体定量分析的大小球三步同位素稀释质谱法 ,并给出其实验模型和不确定度理论分析结果。通过引入三步稀释过程 ,不涉及稀释剂的纯度、丰度、添加质量等方面的数据 ,仅需测定各步稀释剂质量之比 ,在其中的两步反稀释过程中使用了基标准纯物质 ,从而使微量气体的定量分析结果可溯源至基标准纯物质。该方法解决了已有同位素稀释质谱法在微量气体定量分析中的难题。

基于PLC的机械手分拣大小球系统设计

机械手能够部分地代替人的劳动并能达到生产工艺的要求,遵循一定的程序、时间和位置来完成工件的传送,还能大大地改善 工人的劳动条件,加快实现工业生产机械化和自动化的步伐。

自动分拣大小球控制系统的设计

为了顺利分拣出流水线生产的产品,而设计了PLC控制的自动分拣大小球系统。该系统能够通过PLC控制两台电动机的正反转,分别实现机械臂的上、下、左、右运行,从而完成了机械臂从原点的下行、判断、抓取、上行、摆动、存放、复位等一系列动作。首先介绍系统的功能及原理,接下来对系统的主电路及软硬件进行详细介绍。最后仿真结果表明:本文设计的大小球分拣控制系统具备智能化程度高、安全可靠、灵活方便等优点。

基于PLC的分拣控制系统项目教学研究

大小球分拣控制是"可编程控制器原理及应用"课程中的一个重要教学任务,通过学习此项目,使学生掌握顺序功能图及顺序控制指令,掌握使用顺序功能图法设计系统程序。在教学过程中,让学生作为主体,以工作过程为引导,采取项目教学模式培养学生在信号与机电控制系统设计以及设备维修等岗位的工作能力。

机械手分选大、小球的PLC控制

在当前的机械行业工作中,机械手能遵循一定的生产工艺要求和工作方式来完成工件的分选及传递,但在实际使用中经常会遇到有多种机械手的工作选择方式,比如:手动、自动、单周期、单步、回原点等。这种情况经常使一些编程者头疼,甚至不知该从何入手。通过机械手分选大、小球的PLC控制,详细介绍了IST指令的特点和应用。它与STL指令一起使用,专门用来设置具有多种工作方式的控制系统的初始状态和设置有关的特殊辅助继电器的状态,可以大大简化复杂的顺序控制程序的设计工作。

Recharge and Groundwater Quality of an Alluvial Aquifer： Case of the City of N＇djamena （Chad）

Isotopic tracers and water quality indicators （TDS （Total Dissolved Solid）, Cl^- and NO3^-contents） were used to characterize the recharge and control of the quality of groundwater in the alluvial aquifer beneath of the N＇djamena city. For this study, a total of 92 waters samples were taken and this included 67 wells, 21 pumps and 4 surface waters. Some groundwater has 6180 and 62H values close to those of the city of N＇djamena and/or the Chad river rains. However, all sampled points are below the Global Meteoric Water Line reflecting their evaporated characters. The interpretation of the isotopic tracers highlights that the recharge of the analyzed ground waters may result from two major mechanisms： （1） direct infiltration of local precipitation; （2） lateral inflow of river waters. The upper aquifer is the most vulnerable to pollution, especially during the recharge period. This pollution is due to the leaching of soils during the rainy season and the rise of the groundwater level which accompanies the overflowing of the Chad and causes the leaching of the polluted horizons of the unsaturated zone. In contrast, the lower aquifer has acceptable concentrations of solutes.

Expression of estrogen receptor (ER) -α and -βtranscripts in the neonatal and adult rat cerebral cortex, cerebellum, and olfactory bulb

In the present study expression of estrogen receptor subtype -alpha (ERalpha) and -beta (ERbeta) in the cerebral cortex, cerebellum, and olfactory bulb was investigated and compared between neonatal (1 to approximately 3-days-old) and adult (250 to approximately 350 g) rats, using reverse transcription-polymerase chain reaction (RT-PCR). No ERalpha transcripts were detectable in the adult cerebellum and olfactory bulb, whereas very weak expression of ERalpha was present in the adult cerebral cortex. No significant difference in ERbeta transcripts was detectable between the neonatal and adult rats. While transcripts for both ER subtypes were co-expressed in these brain areas of neonatal rats, although ERalpha expression was significantly weaker than ERbeta. Even in the cerebral cortex known to contain both ER subtypes in adult rats, ERalpha transcripts in neonatal rats were much higher than in adult. These observations provide evidence for the existence of different expression patterns of ERalpha/ERbeta transcripts in these three brain areas between the neonatal and adult rats, suggesting that each ER subtype may play a distinct role in the regulation of differentiation, development, and functions of the brain by estrogen.

Variations of the Atlantic and Pacific Blocking Anticyclones and Their Correlation in the Northern Hemisphere

Blocking is a large-scale, mid-latitude atmospheric anticyclone that splits the westerly into two jets and has a profound effect on local and regional climates. This study examined the seasonal, interannual, and decadal variability of the Atlantic and Pacific blocking anticyclones in the Northern Hemisphere based on the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis data between 1958 and 1999. The preferred blocking region during these forty-two years was located over the Atlantic. Most blocking anticyclones over the Atlantic occurred in spring, while most of those over the Pacific occurred in winter. Similar two-to four-year and eleven-year oscillations were found for both the Atlantic and Pacific blocks by using wavelet analysis. The dominant mode for the Pacific blocks is decadal variation, while for the Atlantic blocks the predominant one is interannual variation with a period of about three years. The frequencies of the Pacific and Atlantic blocks varied almost in phase on interannual time scales except during the period of 1965-1977, and frequencies were out of phase on decadal time scale throughout the forty-two years.

Distribution of Origanum vulgare L. and Population Dynamics During the Last Decade in Armenia

This paper examines the distribution and structure of populations of a medicinal and culinary herb native to Armenia. As one of the first countries to join the Convention on Biological Diversity （CBD）, Armenia has a strong interest in assessing the biodiversity of its native flora and identifying threats to the conservation of these species, particularly those with economic value. Only limited information, however, is available at this time on the genetic biodiversity, population location, structure and size, and conservation status of most of these species. This paper reports the results of five consecutive years of field studies conducted in Armenia to 1） re-locate native populations of the important medicinal and culinary herb, Origanum vulgare L., 2） locate new populations, and 3） assess the growth pattern and dynamics of the populations. The quadrat sampling technique was used to identify key elements that determined population size and abundance. GPS maps of present and past population distributions were created. Particular habitat and environmental factors were identified as crucial to predicting the future conditions of these populations under the impact of global climate change. The research provides a baseline dataset that can be used for the development of further conservation strategies of this important medicinal and culinary species in Armenia.

Anti-infectious efficacy of essential oil from Caoguo(Fructus Tsaoko)

OBJECTIVE: To evaluate the anti-infectious efficacy of essential oil extracted from Caoguo(Fructus Tsaoko).METHODS: Minimum inhibitory concentrations(MICs) against clinical isolates of three extracts andthe essential oil from Caoguo(Fructus Tsaoko) were determined by the agar dilution method. The anti-infectious efficacy of the essential oil was evaluated using a mouse peritonitis model which was infected with Staphylococcus aureus or Escherichia coli. The chemical components of the essential oil were identified.RESULTS: The results showed that the essential oil exhibited strong antibacterial activity in vitro, with MICs ranging from 22.49 to 1438.91 μg/m L. The results of in vivo anti-infectious efficacy showed that the Caoguo(Fructus Tsaoko) essential oil can protect the mice from Staphylococcus aureus or Escherichia coli infection. The compositions of the essential oil and relative component percentages were examined. A total of 32 compounds, were identified. The major compounds of essential oil were 1,8-cineole(25.92%) and geraniol(13.69%).CONCLUSION: Our findings suggest that Caoguo(Fructus Tsaoko) essential oil has broad-spectrum antibacterial properties. It warrants further investigation as an antibacterial agent targeting some bacterium with multi-drug resistance.