Effect of strong magnetic field on chemical potential and electron capture in magnetar     

高杰  罗志全  刘伟伟  李港 《海洋学报(英文版)》2010,29(9)

The chemical potential of electrons in a strong magnetic field is investigated. It is shown that the magnetic field has only a slight effect on electron chemical potential when B<10¹¹ T, but electron chemical potential will decrease greatly when B>10¹¹ T. The effects of a strong magnetic field on electron capture rates for ⁶⁰Fe are discussed, and the result shows that the electron capture sharply decreases because of the strong magnetic field.  相似文献   

连云港临洪河口水体中重金属的化学形态与分布特征研究   总被引：1，自引：0，他引：1  

李玉  李谷祺  冯志华 《海洋科学》2010,34(10):33-37

对连云港海域临洪河口水体中重金属元素Cu,Zn,Pb,Cd的主要存在形态及悬浮颗粒态重金属元素的赋存形态进行了分析。结果表明:悬浮态重金属Cu,Zn,Pb,Cd的含量在调查海域内空间分布基本均衡,Zn、Cu、Cd主要以溶解态形式存在,而Pb则主要以颗粒态形式存在。对悬浮态重金属元素的赋存形态分析表明,Cu主要富集在有机-硫化物态、Zn主要富集在残渣态、Pb主要富集在铁锰氧化物态和碳酸盐结合态、Cd主要富集在可交换态和碳酸盐结合态。  相似文献   

Seasonal controls on stream chemical export across diverse coastal watersheds in the USA     

Janet Barco  Stephanie Gunawan  Terri S. Hogue 《水文研究》2013,27(10):1440-1453

The current study focuses on understanding key factors controlling geochemical export in eight diverse coastal watersheds at seasonal and annual time scales. Geochemical, atmospheric and hydrologic data across a range of hydro‐climatic regimes and varying land uses were investigated and relationships analysed. A hyperbolic dilution model was fitted for each watershed system to evaluate discharge–concentration relationships. Nitrate concentration effects were observed in watersheds exposed to high atmospheric deposition rates as well as agricultural watersheds, whereas urban watersheds showed nitrate dilution effects. Dilution patterns were observed for calcium, magnesium and sulfate for almost all watersheds. Seasonal loads for almost all constituents were noted to be mainly driven by hydrologic seasonality, but are also dependent on inputs (atmospheric deposition and land use sources). Understanding the primary controls on hydro‐chemical interactions is critical for developing and refining predictive water quality models, especially in coastal watersheds where sensitive downstream ecosystems act as receiving waters for upstream pollutant loads. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Geodynamic modelling of the Century deposit,Mt Isa Province,Queensland     

A. Ord  B. E. Hobbs  Y. Zhang  G. C. Broadbent  M. Brown  G. Willetts 《Australian Journal of Earth Sciences》2013,60(6):1011-1039

This paper is concerned with an example of quantitative modelling of orebody formation as a guide to reducing the risk for future mineral exploration. Specifically, the paper presents a detailed 3–D numerical model for the formation of the Century zinc deposit in northern Queensland. The model couples fluid flow with deformation, thermal transport and chemical reactions. The emphasis of the study is a systems approach where the holistic mineralising system is considered rather than concentrating solely on the mineral deposit. In so doing the complete plumbing system for mineralisation is considered with a view to specifying the critical conditions responsible for the ore deposit occurring where it does and having the size and metal grades that are observed. The numerical model is based on detailed geological, tectonic, isotopic and mineralogical data collected over the past 20 years. The conclusions are that the Century zinc deposit is located where it is because of the following factors: (i) a thermal anomaly is associated with the Termite Range Fault due to advection of heat from depth by fluid flow up the Termite Range Fault; (ii) bedding‐plane fissility in the shale rocks hosting the Century zinc deposit has controlled the wavelength and nature of D₁ folding in the vicinity of the deposit and has also controlled increases in permeability due to hydrofracture of the shales; such hydrofracture is also associated with the production of hydrocarbons as these shales passed through the ‘oil‐window’; (iii) Pb–Zn leached from crustal rocks in the stratigraphic column migrated up along faults normal to the Termite Range Fault driven by topographic relief associated with inversion at the end of the Isan Orogeny; these fluids mixed with H₂S derived at depth moving up the Termite Range Fault to mix with the crustal fluids to precipitate Pb–Zn in a plume downstream from the point of mixing. Critical factors to be used as exploration guides are high temperatures, carbonaceous fissile shales now folded into relatively tight D₁ folds, fault‐controlled plumbing systems that enable fluid mixing, depletion of metals upstream of the deposit and,in particular,a very wide Fe‐depletion halo upstream of the deposit.  相似文献   

P–T–t evidence for mechanisms of vertical tectonic motion in a contractional orogen: north-western US and Canadian Cordillera     

Whitney  Miller  & Paterson 《Journal of Metamorphic Geology》1999,17(1):75-90

The >1800 km long Coast Mountains–North Cascades orogen of the Canadian Cordillera and north-western US developed as a continental magmatic arc. Metamorphic rocks in the orogen contain widespread evidence for burial of supracrustal rocks to depths of c. 40 km, followed by nearly isothermal decompression to depths of <10 km. Near many shallowly-emplaced, mid-Cretaceous plutons, low-pressure contact metamorphic effects were overprinted by high-pressure regional metamorphic minerals and textures, as evidenced by kyanite±staurolite pseudomorphs after andalusite in metapelitic rocks. Therefore, near-pluton rocks record the loading history of the orogen. Metapelitic rocks not associated with plutons only preserve evidence for high-pressure conditions and/or high-temperature decompression, as indicated, for example, by sillimanite and cordierite after kyanite and garnet, respectively. Petrological evidence for burial and decompression is therefore recorded in different rocks. Various regions of the orogen differ in timing of metamorphism, the overall shape of P–T paths and the relative timing and regional extent of the high-pressure event, but most of these data and observations are consistent with thrusting and/or pure shear thickening as primary loading mechanisms throughout the orogen, as opposed to magma-dominated loading. This interpretation is further supported by comparison with thermal models, which demonstrate that the P–T paths are consistent with simultaneous thrusting and folding at a high initial geothermal gradient (35–40 °C km^?1) in much of the orogen. A high geothermal gradient supports tectonic models invoking intra-arc contraction and suggests that magmatism played an important role in regional temperature-time paths. This tectonic-thermal history may be typical of other contractional orogens and illustrates the importance of large vertical displacement of crust in magmatic arcs.  相似文献   

海绵内生真菌胞外多糖理化性质及自由基清除活性研究     

陈荫  郭守东  徐健  陈艳丽  李红燕  齐晓辉  毛文君 《中国海洋大学学报(自然科学版)》2010,40(5)

从1株海绵内生真菌(Alternaria sp.)链格孢菌的发酵液中提取胞外多糖,对其进行Q Sepharose FF离子交换色谱分离纯化,得到2个组分JJY-W和JJY-S。运用各种化学方法及波谱方法对JJY-W和JJY-S的理化性质及结构进行分析,并对多糖清除自由基活性进行了评价。结果表明,JJY-W和JJY-S的分子量分别为1.4KD和1.8KD;JJY-W以半乳糖、葡萄糖为主,含有少量甘露糖,摩尔比为:甘露糖∶葡萄糖∶半乳糖=1∶2.5∶11。JJY-S以甘露糖、葡萄糖为主,含有少量半乳糖,摩尔比为:甘露糖∶葡萄糖∶半乳糖=3∶2∶1。JJY-W总糖含量为46.3%,未检测出糖醛酸,蛋白含量为2%。JJY-S总糖含量为52%,糖醛酸含量为6.1%,蛋白含量为14%。活性分析表明,2种多糖均具有一定的体外抗氧化活性,并随着浓度的增加清除自由基能力均增强,JJY-W清除DPPH自由基的活性要强于JJY-S,而JJY-S清除OH.自由基的活性要强于JJY-W。  相似文献   

泉州湾表层沉积物元素特征及其地球化学意义     

官宝聪  雷怀彦  林炳煌  柳浩然  史跃中  林建宁 《台湾海峡》2010,29(1):58-65

根据2008年泉州湾调查采集的样品，测定了泉州湾表层沉积物中常量元素和微量元素的含量，采用相关分析和因子分析进行元素组合特征的研究，讨论了它们的分布趋势、相互关系和主要来源，并探讨了其地球化学意义．元素相关分析结果表明，泉州湾表层沉积物常量元素与微量元素含量的相关性明显，表层沉积物成分以SiO2和Al2O3为主，其含量的最高值分别达78．39％和22．02％（m／m），其中SiO2与大部分常量元素、微量元素的含量呈负相关，而Fe2O3、MgO、Cu、Co、Ni、Rb、Pb与Al2O3含量之间呈强正相关．元素因子分析表明，泉州湾表层沉积物的物质来源主要有陆源和生物源2种，以陆源的为主．  相似文献   

A numerical study of mechanical behavior of a cement paste under mechanical loading and chemical leaching          下载免费PDF全文

Y. Jia  H.B. Bian  S.Y. Xie  N. Burlion  J.F. Shao 《国际地质力学数值与分析法杂志》2017,41(18):1848-1869

Based on relevant experimental data of a petroleum cement paste under mechanical loading and chemical leaching, an elastic‐plastic model is first proposed by taking into account plastic shearing and pore collapse. The degradation of mechanical properties induced by the chemical leaching is characterized by a chemical damage variable which is defined as the increase of porosity. Both elastic and plastic properties of the cement paste are affected by the chemical damage. The proposed model is calibrated from and applied to describe mechanical responses in triaxial compression tests respectively on sound and fully leached samples. In the second part, a phenomenological chemical model is defined to establish the relationship between porosity change and calcium dissolution process. The dissolution kinetics is governed by a diffusion law taking into account the variation of diffusion coefficient with calcium concentration. The chemical model is coupled with the mechanical model, and both are applied to describe mechanical response of cement paste samples subjected to progressive chemical leaching and compressive stresses. Comparisons between experimental data and numerical results are presented.  相似文献   

环境风险应急管理决策支持系统的设计与实现   总被引：1，自引：0，他引：1  

陈波  葛永慧 《测绘工程》2010,19(5):67-70

针对典型煤化工产业聚集区(太原市晋源区)环境风险应急管理决策支持系统的建立,进行系统功能结构划分和详细设计,并利用ArcGIS Server二次开发,实现在Web环境下地物空间信息的完整表达,地理信息的定位查询,应急救援资源的分类查询和对风险源的实时监控,完成最短路径查询、最邻近设施选择、救援服务区确定等空间分析功能,形成完整的应急响应机制,为应急管理决策提供有力依据。  相似文献   

旧石器遗址强烈化学风化沉积物细粒混合矿物的光释光信号特征及其测年应用     

黄先可  罗泊宁  周力平 《第四纪研究》2019,39(2):438-447

从湖南省北部赤山岛枫树嘴旧石器遗址剖面第2、第3和第4考古层位采集的3个沉积物样品中提取的细粒混合矿物,尝试对其红外释光(IRSL)信号进行研究。实验表明,虽然长石IRSL信号很弱,但仍可以测得信噪比足够高的红外激发后高温红外激发释光(post-IR IRSL)信号。与此同时,样品存在明显的红外激发后蓝光释光(post-IR OSL)信号,并且样品的IRSL与post-IR OSL信号均以快组分为主,这为该地区沉积物利用长石光释光信号定年提供了新的可能。鉴于长石IRSL信号较弱,根据剂量恢复实验结果,本研究采用post-IR IRSL SAR法(50℃红外激发后270℃高温红外激发,pIRIR270℃)进行等效剂量测量,同时也应用post-IR OSL SAR法定年进行比较。实验结果表明,细粒混合矿物的pIRIR270℃等效剂量分别为418.8±13.2 Gy、562.3±18.2 Gy和694.8±17.9 Gy,相对应的post-IR OSL SAR等效剂量结果为345.0±29.4 Gy、409.6±33.7 Gy和424.7±32.2 Gy。假设强烈化学风化未对沉积物的剂量率造成很大影响,基于长石pIRIR270℃信号的释光年龄为89±6 ka、118±8 ka和152±9 ka,比前人所得的石英OSL SAR法年龄老30%~55%(约20~55 ka)。通过对比不同测量条件下获得的等效剂量值来评估长石IRSL信号是否存在晒退问题,没有发现长石post-IR IRSL信号存在晒退不完全的证据。根据本研究post-IR IRSL SAR法测年结果,赤山岛枫树嘴旧石器遗址似阿舍利技术类型的石器出现在倒数第二次冰期(MIS 6)后期至末次间冰期(MIS 5)前期,比湖南道县福岩洞现代人类牙齿化石年龄(80~120 ka)稍老。作为似阿舍利技术石器制造者的赤山岛古人与福岩洞现代人的关系将是我国旧石器时代考古学和古人类学研究的一个重要课题。  相似文献