On possible release of microbe-containing particulates from a Mars lander spacecraft     

Kenneth Harstad 《Planetary and Space Science》2006,54(3):273-286

Due to possible planet contamination, before Earth-departure, Mars landers and/or rovers are subject to strict requirements on the maximum number of attached spores or particles that carry viable microbes. Estimates of the release rates of these particles on Mars are made considering the three mechanisms of wind shear, collision with suspended dust, and collision with saltating sand particles. The first mechanism is found to apply only to particles of size greater than , the second mechanism has a characteristic particle adhesion half life that is so long as to be of no concern, and the third mechanism is deemed of possible importance, vitally depending on attached particle size and detailed surface characteristics of sand and spacecraft. While not investigated in detail, dust devils are shown to be possible contributors to release of microbe-containing particles.  相似文献   

ICP-MS测定生物样品中的微量金属元素     

王佳丽  李东雷  段英楠 《吉林地质》2007,26(4):69-72

采用SP-60型恒压消解罐消解生物样品,用ICP-MS测定8种金属元素(Mn、Zn、Pb、La、Ce、Mo、Cr和Fe)的质量分数。依据分析结果,比较了消解程序的效果。结果表明,由10.0 mLHNO3对生物样品具有很好的消解能力,各元素的测定值与推荐值相符。  相似文献   

氯化钠盐土壤介电虚部特性的初步研究   总被引：4，自引：0，他引：4  

熊文成  邵芸 《遥感学报》2006,10(2):279-286

含水含盐土壤的介电虚部模型是土壤含水量含盐量的函数。通过一系列关系研究：介电常数虚部ε＂，土壤导电率σa，土壤溶液导电率σw，土壤溶液离子浓度SMv，含盐量S，最终得到介电常数虚部ε＂和土壤含水量Mv。含盐量S的关系，即土壤介电模型。通过微波网络仪，对150组具有不同含水含盐量的土壤，在频率范围0．2-20GHz（频率取样间隔为0．05GHz）进行介电常数测量。在不同频率下，利用这些实测数据通过最佳拟合的方法确定土壤介电模型中的待定参数，从而得到不同频率时土壤介电虚部经验模型。另外，利用吉兰泰地区41个含盐土壤样品进行模型验证，结果表明，模型计算值与测量值高度相关。最后得出：（1）含盐量对介电常数虚部的影响随频率增大而降低；（2）土壤类型和介电常数虚部几乎没有相关性。  相似文献   

The equivalence between different Dark (matter) energy scenarios     

Arbab I. Arbab 《Astrophysics and Space Science》2004,291(2):143-149

We have shown that the phenomenological models with a cosmological constant of the type Λ=β( ) and Λ=3αH ², where R is the scale factor of the universe and H is the Hubble constant, are equivalent to a quintessence model with a scalar (φ) potential of the formV∝φ^-n, n= constant. The equation of state of the cosmic fluid is described by these parameters (α, β, n) only. The equation of state of the cosmic fluid (dark energy) can be determined by any of these parameters. The actual amount of dark energy will define the equation of state of the cosmic fluid.All of the three forms can give rise to cosmic acceleration depending the amount of dark energy in the universe.  相似文献   

埋设地下光缆对武都地电影响的分析   总被引：3，自引：0，他引：3       下载免费PDF全文

高曙德  严正  康好林  苏永刚 《地震工程学报》1999,21(4):433-435

着重探讨武都地电台测区埋设地下光缆后北西道地电阻率测值急剧上升的原因.通过实际观测、理论分析和实验,总结出了这种变化的机制,定量地解释了埋设地下光缆对地电观测的影响,从而为以后判断地电测值变化是干扰还是地震异常提供了依据.  相似文献   

THE INTRINSIC ACIDITY CONSTANTS AND SPECIFIC SURFACE AREA OF MARINE SOLID PARTICLESII. THE RELATIONSHIP BETWEEN THE INTRINSIC ACIDITY CONSTANT AND THE TERNARY SURFACE COMPLEX     

王修林  张正斌  刘莲生 《中国海洋湖沼学报》1992,(1)

This paper deals with the infrared spectra of " amino acid- clay , calcium carbonate and y-AlOOH" and " Cu (II )-clay-amino acid" model systems, and shows that the model of the ternary surface complex is M-OHLCu (L = amino acid) for marine solid particle-Cu (II)-amino acid. Study of the formation mechanism of the ternary surface complex shows that the specific surface area , and especially the intrinsic acidity constant, determine whether the ternary surface complex is easily formed, and that factor, FTSC,quantifies the relationship between the promoting effect of organics on Mt-marine solid particle ion exchange and the intrinsic acidity constant and specific surface area.  相似文献   

Some Homogeneous Bianchi type IX Viscous Fluid Cosmological Models with a Varying Λ     

Anirudh?PradhanEmail author  Sudhir?Kumar?Srivastav  Mahesh?Kumar?Yadav 《Astrophysics and Space Science》2005,298(3):419-432

Some Bianchi type IX viscous fluid cosmological models are investigated. To get a solution, a supplementary condition between metric potentials is used. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density, whereas the coefficient of shear viscosity is considered as proportional to scale of expansion in the model. The cosmological constant Λ is found to be positive and is a decreasing function of time, which is supported by results from recent supernovae observations. Some physical and geometric properties of the models are also discussed.  相似文献   

大气边界层湍流能量交换特征研究进展     

李富余张宏升  陈家宜 《气象科技》2004,32(5):305-310

从一维湍流能量平衡方程出发,回顾了近几十年湍流能量平衡方程中的各项以及Karman常数k的研究成果,总结了大气边界层湍流能量交换特征的研究概况和热点问题,并对今后发展趋势做了展望。实验研究表明,湍流能量平衡方程中的各项在不同条件下有不同的形式;传统的能量产生和耗散的局地平衡假设存在不足,特别是在不稳定条件下,垂直的湍流输运和压力脉动对湍流能量收支起了非常重要的作用。Karman常数与Rossby数和Reynolds数无关,在比较光滑的下垫面上k近似等于040±001。  相似文献   

高精度恒误差数字频率计设计   总被引：2，自引：0，他引：2  

周欣 《南京气象学院学报》2000,23(3):435-439

基于高精度恒误差测频原理,采用Ｌａｔｔｉｃｅ的在系统可编程器件（ｉｓｐＬＳＩ）进行数字频率计设计。结果表明,高精度恒误差测频原理是合理的,并对所采用的高精度恒误差测频原理作了深入的理论分析,给出了依据此原理实现的硬件电路。  相似文献   

川北砂岩-泥岩系混合作用地球化学特征   总被引：1，自引：0，他引：1  

孙书勤  刘峰  王建华 《矿物岩石》2000,20(2):19-22

根据沉积岩混合作用判别原理,应用元素铬－钍判别法,判明川北砂岩－泥岩系为二元混合成因。再根据二元混合元素丰度关系定律,由混合变换式求出丰度关系常数,认为川北砂岩－泥岩系既具有互稀释混合作用,又具有稀释混合作用,进而可以对沉积岩端员物质组成进行估算。  相似文献