同步辐射软X射线吸收谱与发射谱测定天然针铁矿能带结构     

丁聪  李艳  李岩  鲁安怀 《岩石矿物学杂志》2016,35(2):349-354

天然半导体矿物由于成分、缺陷复杂,传统测试方法如紫外可见漫反射等难以准确测定其禁带宽度.本文以针铁矿为例,通过第一性原理计算得到纯针铁矿及掺Al针铁矿的电子结构.计算结果显示,纯针铁矿导带底与价带顶均由Fe3d与O2p轨道组成,而当含杂质Al时,Al2p与O2p发生杂化参与了价带组成.在此基础上,利用同步辐射X射线氧的K边吸收谱与发射谱对纯针铁矿及天然针铁矿的能带结构进行了测定.结果表明,天然含Al的针铁矿禁带宽度为2.30eV,小于纯针铁矿(2.57eV).本研究提供了一种测定天然氧化物矿物禁带宽度的新方法,为深入研究天然半导体可见光催化活性产生机制提供了理论依据.  相似文献   

Numerical implementation of the installation/mooring line and application to analyzing comprehensive anchor behaviors     

《Applied Ocean Research》2016

With the application of innovative anchor concepts and advanced technologies in deepwater moorings, anchor behaviors in the seabed are becoming more complicated and pose a great challenge to the analytical methods. In the present work, a large deformation finite element (FE) analysis employing the coupled Eulerian–Lagrangian technique is performed to simulate the installation/mooring line, and then is applied to analyzing comprehensive anchor behaviors in the seabed. By connecting cylindrical units with each other using connector elements, the installation/mooring line is constructed. With the constructed installation/mooring line, FE simulations are carried out to investigate comprehensive anchor behaviors in the seabed, including long-distance penetration of drag anchors, keying of suction embedded plate anchors and non-catastrophic behavior of gravity-installed anchors. Through comparative studies, the accuracy of the proposed method is well examined. A parametric study is also undertaken to quantify the effects of the frictional coefficient, initial embedment depth, and soil weight on the profile of the embedded anchor line and the shackle load. The present work demonstrates that the proposed FE model, which incorporates the installation/mooring line and the anchor, is effective in analyzing the comprehensive anchor behaviors in the seabed.  相似文献   

固相吸附毒素跟踪技术(SPATT)在浙江南麂海域的应用     

渠佩佩  杨晶晶  徐轶肖  高寒  佟蒙蒙 《海洋与湖沼》2016,47(4):795-803

浙江南麂岛海域是我国近岸贝类的重点养殖区,近年来一直遭受脂溶性贝类毒素(lipophilic shellfish toxins,LSTs)的污染,威胁着人类健康。为了建立有效的食品安全预警方法,本研究利用固相吸附毒素跟踪技术(solid phase adsorption toxin tracking,SPATT)在该海域进行了为期一年的野外监测和LSTs毒素分析。结果表明:7种LSTs毒素在SPATT(DIAION?HP20)中被检出,分别是大田软海绵酸(okadaic acid,OA)、鳍藻毒素-1(dinophysistoxin-1,DTX-1)、虾夷扇贝毒素(yessotoxin,YTX)及其衍生物homo YTX、扇贝毒素-2(pectenotoxin-2,PTX-2)及其衍生物7-epi-PTX2sa和环亚胺毒素(gymnodimine,GYM);有8种毒素在厚壳贻贝(Mytilus galloprovincialis)中被检出,分别是OA、DTX1、homo YTX、PTX2、7-epi-PTX2sa、GYM、原多甲藻酸贝类毒素-3(azaspiracid-3,AZA-3)和虾夷扇贝毒素衍生物45-OH-homo YTX。整体而言,SPATT(HP20)中吸附的毒素种类与贝肉中监测出的毒素种类大体上一致,且两者间OA、DTX1和PTX2的浓度在时间上具有较好的相关性,可见SPATT(HP20)对这些LSTs毒素具有较高的灵敏度,有望作为水体中LSTs毒素的预警监测材料。南麂岛海域LSTs分布特征明显,夏季最高,其次是春秋季,冬季最低,其中2014年夏季贝肉中OA毒素含量高达77.19ng/g贝肉,超出国家限量标准(45ng/g贝肉)比例达11.76%,为浙江南麂海域贻贝的食用安全带来隐患。  相似文献   

Linking foraging behavior and diet in a diving seabird          下载免费PDF全文

Sabrina Harris  Flavio Quintana  Javier Ciancio  Luciana Riccialdelli  Andrea Raya Rey 《Marine Ecology》2016,37(2):419-432

Foraging behavior and diet of breeding seabirds may be analysed simultaneously with the combined use of remote sensing devices and stable isotope analysis. Imperial shag, Phalacrocorax atriceps, breeding at Punta León colony, Argentina, were equipped with global positioning system (GPS) loggers to record foraging trips and blood samples were taken after removal of the devices in order to analyse their nitrogen and carbon stable isotope composition in whole blood and plasma. Whole blood was correlated to plasma isotopic composition for each individual (n = 35), linking diet in the short and medium term. Sexes did not differ in isotopic signatures. The maximum distance reached and the total number of dives that individuals made on two consecutive foraging trips were correlated to their plasma nitrogen isotopic signature. Individuals that went further from the colony and dived fewer times presented more positive signatures, indicative of benthic prey consumption (e.g. Raneya brasiliensis). Diet was predominantly benthic with some individuals incorporating pelagic prey (Engraulis anchoita) and even cephalopods (Octopus tehuelchus). Within breeding pairs (n = 9), different combinations of foraging and prey preferences were observed. Estimated trophic levels of these individuals were similar to those of the same species in other colonies further south along the Patagonian coast.  相似文献   

Microstructural characteristics of the Whitby Mudstone Formation (UK)     

《Marine and Petroleum Geology》2016

When trying to improve gas productivity from unconventional sources a first aim is to understand gas storage and gas flow potential through the rock by investigating the microstructure, mineralogy and matrix porosity of unfractured shale. The porosity and mineralogy of the Mulgrave Shale member of the Whitby Mudstone Formation (UK) were characterized using a combination of microscopy, X-ray diffraction and gas adsorption methods on samples collected from outcrops. The Whitby Mudstone is an analogue for the Dutch Posidonia Shale which is a possible unconventional source for gas. The Mulgrave shale member of the Whitby Mudstone Formation can microstructurally be subdivided into a fossil rich (>15%) upper half and a sub-mm mineralogically laminated lower half. All clasts are embedded within a fine-grained matrix (all grains < 2 μm) implying that any possible flow of gas will depend on the porosity and the pore network present within this matrix. The visible SEM porosity (pore diameter > 100 nm) is in the order of 0.5–2.5% and shows a non-connected pore network in 2D. Gas adsorption (N2, Ar, He) porosity (pore diameters down to 2 nm) has been measured to be 0.3–7%. Overall more than 40% of the visible porosity is present within the matrix. Comparing the Whitby Mudstone Formation to other (producing) gas shales shows that the rock plots in the low porosity and high clay mineral content range, which could imply that Whitby Mudstone shales could be less favourable to mechanical fracturing than other gas shales. Estimated permeability indicates values in the micro-to nano-darcy range.  相似文献   

Study of Influence of Regional Geodynamic Background on Strata Behaviors in China's Tongxin Mine          下载免费PDF全文

Ying Chen  Hongwei Zhang  Bin Yu  Zhijie Zhu  Wenda Wu  Yunpeng Li 《Resource Geology》2016,66(1):1-11

Strata behaviors are mainly affected by regional geodynamic background. The influence of rock mass stress and energy distribution on strata behaviors in the Tongxin mine is studied in terms of regional tectonic movement, seismic activity and tectonic stress field. The results show that the extrusion lifting movement of Kouquan fault adjacent to the Tongxin mine results in the stress concentration in the rock of the Carboniferous coal bed and accumulation of a large amount of elastic energy and forms structural background of Tongxin mine. Due to various seismic activities in the mine area, the strain energy is known to reach much higher levels, up to 0.5×10⁸ J^1/2. Since the stratigraphic structure is sensitive to the mining operation, the strain energy could cause strong strata behaviors. A special geological structure model of the Tongxin mine is established based on the geodynamic division method. The distribution of regional structure stress field is determined by the rock mass stress analysis system. Based on this model, Tongxin mine is divided into five areas with high stress, eight areas with low stress and eight areas with gradient stress. The strong strata behaviors mostly occur in high stress areas. These results could provide guidance to predict the strength of regional or mine pressure and control strata behavior in different areas.  相似文献   

深部地质钻探钻柱失效行为分析          下载免费PDF全文

王志刚  梁健  刘秀美 《探矿工程》2018,45(12):28-31,46

国家的“三深一土”规划确定全面开展深地探测,而在深地探测中钻柱是最重要的连接纽带,其长期在充满钻井液的井眼内工作,受力十分复杂,且受腐蚀、磨损、温度等影响,极易发生钻柱失效事故,造成重大经济损失。研究发现,振动是引起钻柱失效的主要原因,但是深部地质钻探中除了振动引起钻柱失效外,还包括钻柱质量因素、人为因素、钻井质量、套管下入因素、测斜因素以及钻井液因素引起的钻柱失效,本文针对这些影响因素提出了对应的预防措施。同时随着地质钻探井深的不断加深,地质钻探钻柱动力学研究会变得越来越重要,这就需要地质钻探人员在充分考虑地质钻探钻柱失效影响因素的前提下,加大对地质钻探钻柱动力学的研究,以更好地保证深部地质钻探的顺利进行。  相似文献   

斑岩型钼矿床研究进展与问题   总被引：1，自引：0，他引：1  

曹冲  申萍 《地质论评》2018,64(2):477-497

本文在简要介绍全球重要成矿带斑岩型钼矿床品位、储量、时空分布以及构造背景的基础上,着重归纳了斑岩型钼矿床中Mo在岩浆—热液演化过程中的地球化学行为特征以及Mo在成矿流体中的迁移与沉淀机制两个方面的研究进展。取得了以下认识:形成斑岩型钼矿床成矿岩浆氧逸度(f_(O2))变化范围较大,但一般大于铁橄榄石—磁铁矿—石英(FMQ)缓冲体系。斑岩钼矿床形成的主要受岩浆房的大小,大体积的岩浆流体能否高效聚集到浅部岩株或岩脉,岩浆中的挥发分(例如F)含量等因素的控制,但与成矿花岗岩和出溶流体中Mo的含量高低无直接关系。成矿流体的氧逸度与p H降低对辉钼矿沉淀具有关键作用。除此之外,温度与盐度降低对辉钼矿沉淀也有重要作用。流体的多阶段沸腾可能对提高Mo品位具有重要意义。此外,应加强岩浆结晶分异过程、岩浆热液转化过程Mo的地球化学行为研究。  相似文献   

高温与冻融循环对水热炭和生物炭吸附污染物的影响     

关俊杰  刘雨嫣  刘思源  陈家玮 《现代地质》2021,35(4):931-939

将农林废弃物通过不同碳化方式制备成水热炭或生物炭,用于土壤改良和环境污染修复,是当前研究和应用的热点领域。由于受到不同自然条件的长期影响,如环境温度变化,水热炭和生物炭会发生老化作用,从而影响其对污染物的吸附能力,因此,评估老化作用对碳化材料吸附能力的影响是一个重要的科学问题。采用高温和冻融循环2种加速老化方式模拟自然界中的温度变化,对稻壳和玉米秸秆水热炭、生物炭进行老化培养,通过元素分析仪、傅里叶红外光谱分析仪、扫描电子显微镜等手段对老化前后水热炭、生物炭样品的物化性质进行分析,通过批实验对比研究2种新鲜炭材料对Cd(II)及莠去津的吸附能力及吸附稳定性,并研究了30、60、90次老化循环后生物炭和水热炭吸附能力的变化。结果表明,生物炭对Cd(II)和莠去津有良好的吸附稳定性,而水热炭对莠去津的吸附稳定性较差。2种老化作用均使水热炭、生物炭表面含氧官能团增加,从而增强了水热炭、生物炭对Cd(II)和莠去津的吸附能力。在高温和冻融环境中,随着老化时间的持续,生物炭比水热炭更容易受到环境的影响。研究相关成果对于水热炭和生物炭合理应用于不同环境的污染修复具有试验参考价值。  相似文献   

搬迁农户生计策略与土地利用行为耦合协调度分析--以贵州省习水县为例     

杨林  汪磊 《上海国土资源》2021,(1):58-62,83

易地扶贫搬迁改变了搬迁农户生计策略,同时影响了其土地利用行为,二者之间的耦合协调度直接影响着农户的可持续生计。本文以贵州省习水县易地搬迁农户调研数据为基础,构建以农户生计策略和土地利用行为为子系统的耦合协调度模型,分析2个子系统之间的耦合关系和耦合协调关系。研究表明:纯农型农户、农兼型农户、兼农型农户生计策略与土地利用行为之间的耦合度值介于0.4~0.5之间,水平较低,处于拮抗状态;不同类型农户生计策略与土地利用行为系统耦合协调度值均处于0.39~0.49之间,处于濒临失调阶段,存在较大优化空间;传统的农业生产形式对于改善农户生计无明显效果,引导农户向专业农业型农户转变对于促进移民安置区“人地系统”协调发展大有裨益。研究结果可为农户生计与土地利用的可持续发展提供理论依据。  相似文献