城市居民中暑流行病学特征及其与气象因子的关系

利用武汉市1994～2000、2002～2005年共11年1 231个中暑病例资料和逐日相关气象资料,采取有关统计学方法,对该市居民中暑流行病学特征及其与气象因子的关系进行了分析。结果表明,一年之中,中暑主要发生在6～9月,以7月中、下旬和8月上旬中暑患者最多;一天之中,中暑主要发生在09～20时,10～11时、14～15时为中暑发生高峰期;当气温在34.5～36.5℃、相对湿度在55%～60%之间时,中暑患者相对集中。     

微波消解-氢化物发生原子荧光光谱法测定粉煤灰中的硒

粉煤灰中含有的硒元素较高,有综合利用价值.由于基体的复杂性,并未形成成熟可靠的测定技术.本文参考煤炭样品和土壤样品中硒的原子荧光光谱分析方法,采用氢化物发生-原子荧光光谱法测定粉煤灰中的硒.样品经氢氟酸-硝酸-双氧水体系微波消解得到清亮、透明的消解液,消解液经浓盐酸还原后,加入三价铁盐消除共存元素的干扰,所加的铁盐量不干扰硒的测定.方法检出限为0.020 μg/g;平行测定5份粉煤灰样品,相对标准偏差低于4.2％;加标回收率为94.0％～105.0％.应用建立的方法对煤飞灰标准物质进行分析,测定值与标准值基本相符;对不同地区的实际粉煤灰样品进行分析,证实方法可靠,可用于粉煤灰中硒元素的测定.     

Retrieval of the Change of Precipitable Water Vapor by GPS Technique

The feasibility of GPS precipitable water vapor (PWV) is discussed based on the comparison of Radiosonde and GPS PWV where the correlation coefficient is 0.94 and the RMS is 4.0 mm. PWV change in the C...     

基于VRMap平台上的电子沙盘研制

通过与国内外数字沙盘制作方式及功能的比较，详细介绍了数字沙盘研究方面的一些方法，并以中原油田数字沙盘的研制为例，选择北京灵图公司的VRMap2．3软件作为平台制作中原油田数字沙盘，为油田开发提供基本资料。     

Rank statistical analysis of nickel sulphide resources of the Norseman-Wiluna Greenstone Belt,Western Australia

Estimating the undiscovered mineral resources of a terrane is a challenging, yet essential, task in mineral exploration. We apply Zipf’s law rank statistical analysis to estimate the undiscovered nickel sulphide resources in the Norseman-Wiluna Greenstone Belt, Western Australia. The analysis suggests that about 3.0 to 10.0 Mt of nickel sulphide resources are yet to be discovered in this belt, compared to the currently known total nickel sulphide endowment of 10.8 Mt. This undiscovered nickel sulphide endowment is likely to be hosted by incompletely delineated deposits and undiscovered deposits in less explored komatiites in the belt. Using the more detailed data subset of the Kambalda domain, this study manipulates Zipf’s law to estimate the sizes of undiscovered deposits, in addition to the domain’s total nickel sulphide endowment estimate. Importantly, regression analysis shows that the gradient of the line of best fit through the logarithmic rank-size plot for the detailed Kambalda data subset is −1. This gradient, which is the key Zipf’s law constant k, has the value of −0.92 for the Norseman-Wiluna Greenstone Belt which is collectively less mature than the Kambalda domain. This result corroborates the use of k = −1 in Zipf’s law predictive analyses of mineral resources for deposit populations for which the value of k = −1 has not yet been attained due to exploration immaturity.     

The Metastable Phase Equilibria of the MeX-MgCl_2-H_2O Systems

正1 Introduction The Pingluoba brine,which characterized as high concentration with sodium,potassium,boron,lithium,and rubidium,possess great development value.The main composition of the brine can be summarized to the     

Characterization,dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(Pb<Subscript>x</Subscript>Ca<Subscript>1−x</Subscript>)<Subscript>5</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>OH] at 25 °C and pH 2–9

Background

The interaction between Ca-HAP and Pb²⁺ solution can result in the formation of a hydroxyapatite–hydroxypyromorphite solid solution [(Pb_xCa_1?x)₅(PO₄)₃(OH)], which can greatly affect the transport and distribution of toxic Pb in water, rock and soil. Therefore, it’s necessary to know the physicochemical properties of (Pb_xCa_1?x)₅(PO₄)₃(OH), predominantly its thermodynamic solubility and stability in aqueous solution. Nevertheless, no experiment on the dissolution and related thermodynamic data has been reported.

Results

Dissolution of the hydroxypyromorphite–hydroxyapatite solid solution [(Pb_xCa_1?x)₅(PO₄)₃(OH)] in aqueous solution at 25 °C was experimentally studied. The aqueous concentrations were greatly affected by the Pb/(Pb + Ca) molar ratios (X_Pb) of the solids. For the solids with high X_Pb [(Pb_0.89Ca_0.11)₅(PO₄)₃OH], the aqueous Pb²⁺ concentrations increased rapidly with time and reached a peak value after 240–720 h dissolution, and then decreased gradually and reached a stable state after 5040 h dissolution. For the solids with low X_Pb (0.00–0.80), the aqueous Pb²⁺ concentrations increased quickly with time and reached a peak value after 1–12 h dissolution, and then decreased gradually and attained a stable state after 720–2160 h dissolution.

Conclusions

The dissolution process of the solids with high X_Pb (0.89–1.00) was different from that of the solids with low X_Pb (0.00–0.80). The average K _sp values were estimated to be 10^?80.77±0.20 (10^?80.57–10^?80.96) for hydroxypyromorphite [Pb₅(PO₄)₃OH] and 10^?58.38±0.07 (10^?58.31–10^?58.46) for calcium hydroxyapatite [Ca₅(PO₄)₃OH]. The Gibbs free energies of formation (ΔG _f ^o ) were determined to be ?3796.71 and ?6314.63 kJ/mol, respectively. The solubility decreased with the increasing Pb/(Pb + Ca) molar ratios (X_Pb) of (Pb_xCa_1?x)₅(PO₄)₃(OH). For the dissolution at 25 °C with an initial pH of 2.00, the experimental data plotted on the Lippmann diagram showed that the solid solution (Pb_xCa_1?x)₅(PO₄)₃(OH) dissolved stoichiometrically at the early stage of dissolution and moved gradually up to the Lippmann solutus curve and the saturation curve for Pb₅(PO₄)₃OH, and then the data points moved along the Lippmann solutus curve from right to left. The Pb-rich (Pb_xCa_1?x)₅(PO₄)₃(OH) was in equilibrium with the Ca-rich aqueous solution.

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Graphical abstractLippmann diagrams for dissolution of the hydroxypyromorphite–hydroxyapatite solid solution [(Pb_xCa_1?x)₅(PO₄)₃OH] at 25??C and an initial pH of 2.00.

     

船闸泄水作用下引航道中动水冲沙规律

结合工程实际,研究利用船闸泄水进行下游引航道清淤,对减少清淤成本、提高通航效率有着重要的工程价值。建立枢纽及船闸下游引航道的二维水沙数学模型,采用已有模型试验对水流场和泥沙场进行验证。研究引航道及口门区的泥沙淤积规律,在此基础上,分析船闸输水系统的水力特性,研究了不同冲刷流量、冲刷时间和初始淤积厚度下引航道及口门区的冲刷效果,得出船闸泄水量与引航道及口门区最大淤积厚度的关系。结果表明,在同一初始淤积地形和冲刷流量下,引航道及口门区的最大淤积厚度与冲刷时间呈线性变化,冲刷流量越大,泥沙厚度下降的斜率越大。淤积厚度低于一定值后,随冲刷时间的增加,冲刷效果开始减弱。     

Optimal Energy Growth in Current Sheets

In this article, we investigate the possibility of transient growth in the linear perturbation of current sheets. The resistive magnetohydrodynamics operator for a background field consisting of a current sheet is non-normal, meaning that associated eigenvalues and eigenmodes can be very sensitive to perturbation. In a linear stability analysis of a tearing current sheet, we show that modes that are damped as \(t\rightarrow \infty \) can produce transient energy growth, contributing faster growth rates and higher energy attainment (within a fixed finite time) than the unstable tearing mode found from normal-mode analysis. We determine the transient growth for tearing-stable and tearing-unstable regimes and discuss the consequences of our results for processes in the solar atmosphere, such as flares and coronal heating. Our results have significant potential impact on how fast current sheets can be disrupted. In particular, transient energy growth due to (asymptotically) damped modes may lead to accelerated current sheet thinning and, hence, a faster onset of the plasmoid instability, compared to the rate determined by the tearing mode alone.     

利用盐湖常见元素的助烧结作用绿色制备氧化镁及磷酸镁水泥

低活性氧化镁是制备磷酸镁水泥(MPC)的关键原材料。现行低活性氧化镁的生产方式导致了制备MPC具有能耗高和成本高的缺点,不利于其推广应用。利用盐湖中常见元素如B,Na、K和Cl的助烧结作用,在≤1 200℃煅烧盐湖提锂镁渣、外掺B的轻烧镁粉和水氯镁石的热解产物制备低活性氧化镁。介绍了低活性氧化镁的粒径、比表面积、孔隙率、化学组成、矿物组成和形貌等物理特征,以及低活性氧化镁制备MPC的凝结时间、水化产物、微观结构、抗压强度、体积稳定性等凝结硬化性能,并分析了烧结温度对低活性氧化镁的理化性能及MPC的凝结硬化性能的影响。相比现有技术,利用盐湖共存元素的助烧结作用可将氧化镁的烧结温度由1 500～1 800℃降低到1 200℃以下,有利于实现低活性氧化镁及MPC的低能耗、低成本绿色制备,促进MPC的推广应用。