利用谱睿(Pre)在线样品前处理技术检测高碳酸盐基体中阴离子

利用戴安公司全新的谱睿(Pre)在线样品前处理技术,开发了一种柱前在线去除高碳酸盐基体中碳酸盐的方法,解决了以往高碳酸盐基体对其他阴离子测定的影响问题。利用该方法对钢铁洗涤液碳酸钠溶液、固体碳酸钠试剂、商品化碳酸钠淋洗液浓缩液等不同类型的样品分别进行了检测。选择的色谱条件为高容量氢氧化物选择性IonPac AS15阴离子交换色谱柱,淋洗液自动发生装置在线产生KOH进行梯度淋洗,抑制电导检测。该方法在常规离子色谱基础上增加一个输液泵、一个六通阀和一个在线二氧化碳去除器(CRD),提出了不使用浓缩柱作为前处理设备与离子色谱主机之间的接口,而采用大定量环,选取合适的时间窗口这一先进理念。该方法可实现5000 mg/L碳酸盐溶液的在线去除,同时检测出浓度低于50μg/L的氯离子、硝酸根离子、硫酸根离子等阴离子。采用外标法和外延法进行定量,标准曲线线性较好,标准加入回收率为92%~108%。方法具有操作简单、可重复性强、方法新颖等特点,并解决了碳酸根离子对其他阴离子的测定干扰这一离子色谱技术难题。     

波长色散X射线荧光光谱法同时测定钨精矿中主次量组分

建立了采用波长色散X射线荧光光谱测定钨精矿中三氧化钨、锰、铁、氧化钙、二氧化硅、锡、钼、铜、铋、铅、锑、锌、镉、铬等14个主次量组分的方法。采用四硼酸钠和四硼酸锂混合熔剂熔融制样,以高纯物质人工配制校准标准样品,公共背景法进行背景校正,采用可变理论α影响系数法校正基体效应。方法的准确性、精密度达到了传统分析方法的要求,分析时间大大缩短,具有较好的实用价值。     

从江翁浪地区蚀变岩型金矿床常量元素及稀土元素迁移规律研究

根据野外对从江翁浪地区蚀变岩型金矿床内岩石变形特点的分析,在典型剖面中划分出了3个不同的构造变形带,即简单变形带(未蚀变带)、复杂透镜体带(强蚀变带)和叠加透镜体带(弱蚀变带).不同构造带中Au的含量不同,其特点为:复杂透镜体带＞叠加透镜体带＞简单变形带,即Au在构造变形强烈的区域富集.对3个变形带内的常量元素迁移规律和稀土元素特征进行了探讨:①常量元素的迁移规律明显,从叠加透镜体带和复杂透镜体带到简单变形带,明显带出的主要成分为SiO2、MnO、K2O、FeO、TiO2,说明引起蚀变的流体中富含SiO2、MnO等;而P2O5、Fe2O3、MgO、Na2O、CaO等成分明显带入,说明矿化作用导致P2O5、Fe2O3等向矿体迁移富集.②简单变形带的稀土元素总量高于叠加透镜体带和复杂透镜体带,稀土元素配分曲线为右倾型,轻稀土元素富集.δEu都小于1以及δCe都大于1,说明该矿区的成矿环境为氧化性质环境.该矿床样品的稀土元素配分曲线图显示出,大部分矿体和围岩的曲线以及石英脉的曲线与辉绿岩的曲线基本相同,说明矿体的成矿物质大部分来源于深部;矿体与围岩有小部分曲线趋于相同,可认为矿体的成矿物质有小部分来自于围岩.最后,对金的富集机制进行了简要的论讨,认为元素在成矿过程中的迁移能力受到动力变形机制以及元素自身离子半径的影响.     

测绘专业“面向对象程序设计”课程教学实践与思考

根据"面向对象程序设计"课程的特点,探讨该课程在测绘专业课程体系中的定位、传统教学内容与教学方法存在的问题。结合多年科研及教学实践经验,从实际出发,优化、整合教学内容,改进教学方法,取得较好的教学效果,对测绘专业"面向对象程序设计"课程教学改革具有重要的实践意义。     

陕北地区植被治理与退化对一次区域降水过程影响的数值模拟

针对陕北地区一次区域性降雨个例 ,运用中尺度模式MM5V3 5进行了陕北地区植被治理和退化的敏感性试验。结果表明 ,植被生态治理后 ,能够使区域的平均降水量增加 ,使地表净盈余水分 7 6% ;植被退化使降水量减少 ,地表亏失水分 3 6%。植被变化对降水的影响有热力和动力两方面原因 :一方面 ,植被改善后 ,地气之间的热通量增大 ,地表对大气的增温作用增强 ,使低层大气更趋于不稳定 ;另一方面 ,植被改善增大了地表的非均一性 ,能够激发出一定强度的局地次级环流叠加于天气尺度系统上。这两种作用 ,使系统加深并发展 ,增加到达地面的降水量。植被退化则产生与上述相反的作用 ,导致局地降雨量的减小 ,使地面进一步干旱化。     

Electrostatic ion-cyclotron waves in a plasma with heavy negative ions

Results of a laboratory study of electrostatic ion-cyclotron (EIC) waves in a plasma containing K⁺ (39 amu) positive ions, electrons and C₇F₁₄⁻ (350 amu) negative ions are presented. Excitation of the fundamental and higher harmonic light and heavy ion EIC modes was observed. The presence of heavy negative ions in the plasma has a significant effect on the excitation of the light ion EIC modes. The results may be relevant to the understanding of plasma wave properties in plasmas containing negative ions, such as those found in the Earth's ionosphere, the solar system, and, in particular, near Saturn's moon Titan, where an abundance of heavy negative ion species has recently been discovered [Coates, et al., 2007. Discovery of heavy negative ions in Titan's ionosphere. Geophys. Res. Lett. 34, L22103].     

Effects of sand-mulch thickness on soil evaporation during the freeze–thaw period

Control of evaporation from seasonally frozen soil is an important method for alleviating water shortages in arid and semi-arid areas. To investigate the inhibition of soil evaporation by sand and the major factors that influence soil evaporation, a series of field experiments with five sand-mulch thicknesses (0 cm, bare soil [BS], 1 cm [T1], 2 cm [T2], 3 cm [T3] and 4 cm [T4], with an average diameter of 1 mm) were conducted during the freeze–thaw period in Northern China. Soil evaporation characteristics in the three freeze–thaw stages were revealed and the major factors influencing soil evaporation were analysed using grey correlation analysis. The results showed that the cumulative soil evaporation decreased with increasing sand-mulch thickness during the freeze–thaw period, and only small differences in soil evaporation were observed between the T3 and T4 treatments. The reduction in soil evaporation under different sand-mulch thicknesses was 19.2–62.6% in the unstable freezing stage (P1), 2.0–28.3% in the stable freezing stage (P2) and 4.8–20.4% in the thawing stage (P3). In P1, solar radiation was a major factor influencing soil evaporation in all treatments and vapour pressure was a major factor in the sand-mulch treatments, and the influence of relative humidity on soil evaporation decreased in the T4 treatment. During the coldest P2, solar radiation was lowest so that relative humidity and wind speed became the more dominant influence factors on soil evaporation in all treatments, and surface soil water content was a major factor in the sand-mulch treatments. In P3, average air temperature and solar radiation were major factor influencing soil evaporation in all treatments and vapour pressure was a major factor in the BS and T1 treatments, whereas water surface evaporation was the major factor in the T2, T3 and T4 treatments. The results suggest that the addition of sand mulch in agricultural fields may be a beneficial practice to reduce water stress in arid and semi-arid areas.     

Spatio‐temporal patterns of major ions in urban stormwater under cold climate

Multiple natural and anthropogenic factors affect urban water chemistry. However, little is known about the abundance or temporal variation of major ions in urban runoff. This study explores the spatio‐temporal variation of major dissolved ions (Na, K, Ca, Mg, Cl, NO₃, and SO₄) and total dissolved solids (TDS) in cold climate urban stormwater. Three watersheds with varying degrees of urban land use intensity and imperviousness (from 36% to 66%) in Helsinki, Finland, were continuously monitored for 5 years using an automated sampling procedure to obtain stormwater discharge and ion concentrations and, thus, loadings. High‐resolution datasets, including long‐term continuous discharge, both measured and simulated (using Storm Water Management Model), and automatic water quality sampling enabled the accurate calculation of loads of ions and TDS. Water quality was related to explanatory watershed characteristics (e.g., watershed physiography and sampling time) using hierarchical clustering, nonmetric multidimensional scaling, and hierarchical partitioning methods. Urban land use contributed to increased ion concentrations and loads year‐round. This study highlights how stormwater ion concentrations are elevated across seasons, indicating chronic pollution phenomena. The greatest loads occurred during summer (except for Na and Cl), while the highest variation in loads was observed in autumn. Significant clusters among ions were found in the hierarchical cluster analysis, suggesting similar temporal patterns and sources for the ions in each cluster. The importance of land use was evident, though in the most urbanized watershed, concentrations were not linked to any of the investigated watershed characteristics. Based on our results, only Na and Cl are manageable by alternative winter road antiskid practices, whereas other ions resulted from diffuse pollution sources, being therefore more difficult to control. Finally, this study contributes to an increased understanding of the temporal and spatial patterns of ions in stormwater and highlights the need for consistent time series data for ion monitoring under cold climatic conditions in order to enable reliable estimates of their loads to adjacent water bodies. Finally, year‐round stormwater treatment is highly recommended.     

Macroscale and mesoscale analysis of concrete as a multiphase material for biological shields against nuclear radiation

The overall thermo‐hygro‐mechanical behavior of concrete is to be investigated, because its bearing capacity is required together with its shielding properties, specifically when concrete structures are exposed to high‐energy neutron fluxes, which represent the next generation facilities designed for the production of high energy radioactive ion beams in physics research. Irradiation in the form of either fast and thermal neutrons, primary gamma rays or gamma rays produced as a result of neutron capture, are learnt to affect concrete as well as neutron fluences of the order of 10¹⁹ n/cm² and gamma radiation doses of 10¹⁰ rad seem to become critical for concrete strength. The collection of data on concrete samples, variously exposed to neutron radiation, has allowed for defining a law for radiation damage within the FEM research code NEWCON3D, assessing the 3D coupled thermo‐hygro‐mechanical behavior of concrete, modeled as a multiphase porous medium, both at the macroscale and the mesoscale level. The required damage law is thought to be a function of the neutron flux impinging the concrete shielding wall, and a good estimate of this quantity has been provided by means of a Monte Carlo code developed by CERN and the National Institute of Nuclear Physics of Milan, Italy; this code handles radiation transport calculations and represents at this day one of the most reliable procedures for dealing with the interaction of radiation and matter. The suggested procedure for the radiation damage evaluation has allowed for discussing on differences between mesolevel and macrolevel approaches. Stochastic contour maps of the expected radiation field, properly interfaced with the numerical FE code, have allowed for obtaining a more precise evaluation of the radiation damage front as well as its evolution in time. Copyright © 2013 John Wiley & Sons, Ltd.     

非测绘专业摄影测量学教学方法探讨

摄影测量学是测绘专业的一门核心课程,也是土地资源管理、GIS等非测绘专业的一门重要选修课.但由于其理论极为抽象、逻辑非常严密,且涉及大量的数学公式推导,学生容易产生畏难心理.本文主要针对非测绘专业的摄影测量学教学方法问题,从教学内容的优化、教学方法的改进和教学实践的强化等方面进行了探讨.