973 resultados para 700


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Kunyushan composite granite pluton is located in northeast part of the Sulu UHP collisional belt, Jiaodong peninsula, eastern China. It is regarded as the boundary of the Jiaodong block and the Sulu UHP collisional belt. The body is unique in the Dabieshan-Sulu UHP collisional orogen for its feature of multiple intrusions of diverse types granitoid rocks in a long span after UHP the collision between the North China and the Yangtze plates in late Triassic. It can be grouped into four series on the basis of petrology and petrochemistry. They are mid-K calc-alkaline granitoids, strongly peraluminous granites, high-K calc-alkaline granitoids and syenitic granite of shoshonitic series. In this thesis, the later three types of rocks are investigated geochronologically in detail. The grain zircon U-Pb isotope dilution dating technique has been employed in this study. Zircon morphology are presented and discussion on the chemical and physical conditions of the granite formation have been carried out in addtion. Strongly peraluminous granites comprises foliated monzogranite and garnet bearing leucogranite. They occupy more than half of the area of the Kunyushan composite body. Three zircon samples of foliated monzogranites have been analyzed, they yield lower intercept ages mainly in the range of 140-150 Ma. The formation of these rocks was likely to be at 700-600 ℃, implied by zircon morphology. Two zircon samples of the garnet bearing leucogranite yield lower intercept ages from 130 Ma to 140 Ma. Zircon morphology indicate that the liquidus temperature of the magma was about 750 °C. Syenitic granite of shoshonitic series occur in the north central part of the body, and the volume is quite small contrast to other types. One zircon sample was chosen from this rock, and yield lower intercept age of 121+1.8/-2.1 Ma. Zircon morphology indicate that the liquidus temperature of this rock is up to 900 °C, which is much higher than others'. High-K calc-alkaline granitoids can be divided into two types on the basis of rock texture and structure. One is Kf-porphyritic monzogranite. It's outcrop is quite small. Zircon ages of one sample constrain the emplacement of this rock at about 112 Ma. The other is medium-grain to coarse-grain monzogranite. Zircons from it yield lower intercept age of 100.5+2.9/-4.6 Ma. The variation of zircon morphology suggest that these two monzogranites were outcomes of a single magma at different stage. The former emplaced earlier than the latter. The liquidus temperature of the magma was about 800 ℃ Inherited zircon is ubiquitous in the Kunyushan composite body. Most of the samples yield upper intercept ages of late Proterozoic. It was considered that only the Yangtze plate underwent a crustal growth during late Proterozoic among the two plates which involved into the UHP collision. Inherited zircon of about 200 Ma can also be observed in strongly peraluminous and high-K calc-alkaline granitoids. Two samples out of eight yield upper intercept ages of Achaean.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Superfine mineral materials are mainly resulted from the pulverization of natural mineral resources, and are a type of new materials that can replace traditional materials and enjoy the most extensive application and the highest degree of consumption in the present day market. As a result, superfine mineral materials have a very broad and promising prospect in terms of market potential. Superfine pulverization technology is the only way for the in-depth processing of most of the traditional materials, and is also one of the major means for which mineral materials can realize their application. China is rich in natural resources such as heavy calcite, kaolin, wollastonite, etc., which enjoy a very wide market of application in paper making, rubber, plastics, painting, coating, medicine, environment-friendly recycle paper and fine chemical industries, for example. However, because the processing of these resources is generally at the low level, economic benefit and scale for the processing of these resources have not been realized to their full potential even up to now. Big difference in product indices and superfine processing equipment and technologies between China and advanced western countries still exists. Based on resource assessment and market potential analysis, an in-depth study was carried out in this paper about the superfine pulverization technology and superfine pulverized mineral materials from the point of mineralogical features, determination of processing technologies, analytical methods and applications, by utilizing a variety of modern analytical methods in mineralogy, superfine pulverization technology, macromolecular chemistry, material science and physical chemistry together with computer technology and so on. The focus was placed on the innovative study about the in-depth processing technology and the processing apparatus for kaolin and heavy calcite as well as the application of superfine products. The main contents and the major achievements of this study are listed as follows: 1. Superfine pulverization processing of mineral materials shall be integrated with the study of their crystal structures and chemical composition. And special attention shall be put on the post-processing technologies, rather than on the indices for particle size, of these materials, based on their fields of application. Both technical feasibility and economic feasibility shall be taken into account for the study about superfine pulverization technologies, since these two kinds of feasibilities serve as the premise for the industrialized application of superfine pulverized mineral materials. Based on this principle, preposed chemical treatment method, technology of synchronized superfine pulverization and gradation, processing technology and apparatus of integrated modification and depolymerization were utilized in this study, and narrow distribution in terms of particle size, good dispersibility, good application effects, low consumption as well as high effectiveness of superfine products were achieved in this study. Heavy calcite and kaolin are two kinds of superfine mineral materials that enjoy the highest consumption in the industry. Heavy calcite is mainly applied in paper making, coating and plastics industries, the hard kaolin in northern China is mainly used in macromolecular materials and chemical industries, while the soft kaolin in southern China is mainly used for paper making. On the other hand, superfine pulverized heavy calcite and kaolin can both be used as the functional additives to cement, a kind of material that enjoys the biggest consumption in the world. A variety of analytical methods and instruments such as transmission and scanning electron microscopy, X-ray diffraction analysis, infrared analysis, laser particle size analysis and so on were applied for the elucidation of the properties and the mechanisms for the functions of superfine mineral materials as used in plastics and high-performance cement. Detection of superfine mineral materials is closely related to the post-processing and application of these materials. Traditional detection and analytical methods for superfine mineral materials include optical microscopy, infrared spectral analysis and a series of microbeam techniques such as transmission and scanning electron microscopy, X-ray diffraction analysis, and so on. In addition to these traditional methods, super-weak luminescent photon detection technology of high precision, high sensitivity and high signal to noise ratio was also utilized by the author for the first time in the study of superfine mineral materials, in an attempt to explore a completely new method and means for the study of the characterization of superfine materials. The experimental results are really exciting! The innovation of this study is represented in the following aspects: 1. In this study, preposed chemical treatment method, technology of synchronized superfine pulverization and gradation, processing technology and apparatus of integrated modification and depolymerization were utilized in an innovative way, and narrow distribution in terms of particle size, good dispersibility, good application effects, low consumption as well as high effectiveness of superfine products were achieved in the industrialized production process*. Moreover, a new modification technology and related directions for producing the chemicals were invented, and the modification technology was even awarded a patent. 2. The detection technology of super-weak luminescent photon of high precision, high sensitivity and high signal to noise ratio was utilized for the first time in this study to explore the superfine mineral materials, and the experimental results can be compared with those acquired with scanning electron microscopy and has demonstrated its unique advantages. It can be expected that further study may possibly help to result in a completely new method and means for the characterization of superfine materials. 3. During the heating of kaolinite and its decomposition into pianlinite, the diffraction peaks disappear gradually. First comes the disappearance of the reflection of the basal plane (001), and then comes the slow disappearance of the (hkl) diffraction peaks. And this was first discovered during the experiments by the author, and it has never before reported by other scholars. 4. The first discovery of the functions that superfine mineral materials can be used as dispersants in plastics, and the first discovery of the comprehensive functions that superfine mineral materials can also be used as activators, water-reducing agents and aggregates in high-performance cement were made in this study, together with a detailed discussion. This study was jointly supported by two key grants from Guangdong Province for Scientific and Technological Research in the 10th Five-year Plan Period (1,200,000 yuan for Preparation technology, apparatus and post-processing research by using sub-micron superfine pulverization machinery method, and 300,000 yuan for Method and instruments for biological photon technology in the characterization of nanometer materials), and two grants from Guangdong Province for 100 projects for scientific and technological innovation (700,000 yuan for Pilot experimentation of superfine and modified heavy calcite used in paper-making, rubber and plastics industry, and 400,000 yuan for Study of superfine, modified wollastonite of large length-to-diameter ratio).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在密闭体系中, 400~700℃和1~3 GPa的条件下进行了褐煤加水的模拟实验, 分析了实验产物中芳烃的演化特征, 并讨论了高压高温对有机质的演化的影响. 实验结果表明, 高压抑制了液态烃的裂解, 压力升高有利于有机质降解产物的环化、聚合和芳构化; 温度升高, 芳烃的成熟度增加, 压力增加会抑制或延迟油气的生成和有机质成熟, 并且温度越低, 抑制作用越明显. 高压对有机质热演化的影响是非线性的. 该研究结果不仅加深了对俯冲带地幔有机质稳定性的认 识, 而且对认识深层油气成藏及保存也有启示意义.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在密闭体系中压力高达3 GPa, 温度高达700℃的条件下进行了褐煤加水的模拟实验, 分析了实验产物中的烷烃生物标志化合物的变化规律, 并讨论了高压高温对有机质演化的影响. 实验结果表明, 高压抑制了液态烃的生成, 使高峰值后移; 相同压力条件下, 温度升高有利于有机质的成熟演化; 压力增加会抑制或延迟油气的生成和有机质成熟. 高碳数烷烃在地幔高压力条件下仍可以存在, 这不仅突破了“生油窗”的传统概念, 而且还加深了在异常高压高温区寻找油带富集区的认识.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

文章应用三维荧光光谱技术对洱海沉积物孔隙水中的溶解有机质进行了研究。结果表明,所有样品均含有4个明显的荧光峰,其中A和C为类腐殖酸荧光,B和D为类蛋白荧光。荧光强度在沉积物-水界面特别强,在1cm处急剧下降,之后随着沉积深度呈上升趋势。孔隙水溶解有机质均具有强的类蛋白荧光,揭示了溶解有机质中含有大量色氨酸、酪氨酸等芳环结构的类蛋白物质,并且在早期成岩过程中随着沉积深度呈积累趋势;类蛋白荧光与类腐殖酸荧光之间具有一定的相关关系,r(A,C)值在0.94-1.79之间,随着沉积深度逐渐下降,r(D,B)值在0.9-1.75之间,与r(A,C)值极为接近,且随着沉积深度有着类似的变化趋势,说明在洱海沉积物孔隙

Relevância:

10.00% 10.00%

Publicador:

Resumo:

中国南方早震旦世大塘坡期锰矿的形成一直存在热水成因、生物成因、或化学成因的争议。本文通过对贵州松桃早震旦世大塘坡期锰矿的碳、硫同位素和藻类化石的研究,认为早震旦世大塘坡期锰矿的成因是在700-695Ma全球性Sturtian冰期后,由于大气中含有很高的CO2与海洋中的Ca2+, Mn2+反应,造成大量CaCO3和MnCO3快速沉淀,形成“碳酸盐岩帽”(碳酸锰)所致。同时,对大塘坡组藻类化石研究表明,在含锰矿的层位,藻类化石很少,而锰矿层上下,微体藻类化石都很丰富,这说明锰矿成矿与藻类关系并不那么密切。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

云南省大红山铁铜矿床位于康滇地轴南端西缘,介于红河深断裂与绿汁江深断裂所夹持的滇中台坳内,赋存于中元古代大红山群海相火山喷流-沉积岩系中,是我国典型的火山岩型块状硫化物(VHMS)矿床之一。该矿床包括一系列与火山喷发-岩浆侵入活动相关但成因有一定差别的矿床,被统称为“大红山式”铁铜矿床。该矿床经济价值巨大,铁、铜储量均达超大型矿床规模,但其研究程度较低,多停留在矿区地质特征层面上,地球化学研究较为薄弱。本次工作系统地研究了大红山层状铜矿床中各类岩石的岩相学特征,对特征矿物做了电子探针定性和定量分析,挑选火山质岩石中锆石做定年分析,系统分析了岩石的主量元素和微量元素,测定了硫化物的硫和铅同位素,并选取了与富集型硫化物相关的石英脉矿物和碳酸盐矿物分别做流体包裹体和碳、氧同位素研究。论文取得的主要认识如下: 1.红山群曼岗河组火山喷流-沉积年代约为1687±8Ma,即形成于早-中元古代,因此不可能遭受如前人所说的吕梁运动改造作用。在700 ~ 800Ma左右,即晋宁运动期本区遭受了强烈的变质变形以及流体蚀变改造作用。 2.层状铜矿中岩石类型主要为黑云母片岩、白云石钠长石岩和白云石大理岩。黑云母片岩中主要矿物为黑云母、钠长石、铁白云石和石榴子石;白云石钠长石岩中主要矿物为钠长石、铁白云石、石榴子石及少量的黑云母;白云石大理岩中主要矿物为铁白云石,含少量的钠长石和黑云母。岩石原岩恢复表明,三类岩石原岩为火山物质、泥质沉积物和喷流热水沉积混合组成,其中黑云母片岩以泥质为主,包含火山质物质和喷流热水沉积物质;白云石钠长石岩以火山物质和喷流热水为主,含少量的泥质;白云石大理岩以热水喷流沉积为主。 3.本区至少遭受过三期变质作用:区域高温变质作用、流体蚀变改造作用和变形变质作用。区域高温变质作用变质温度最高可达可达660℃,主要集中在600 ~ 630℃之间,形成压力约为4.9 ~ 5.0Kbar。三期变质改造使原岩发生了绿帘-角闪岩相的变质作用,变质过程中,稀土元素(特别是轻稀土元素)和部分高场强元素发生了迁移;流体蚀变改造富集了早期的贫铜矿胚,使之形成工业矿床。 4.硫化物硫同位素研究显示,其δ34S值为-0.6 ~ +10.9‰,主要集中在+5.0 ~ +10.9‰之间。这一组成表明富集型硫化物大体继承了早期硫化物硫源特征,并在改造过程中富集重硫。早期硫化物硫源主要来自岩浆硫和海水无机还原硫。硫化物铅同位素范围为:206Pb/204Pb= 18.985 ~ 23.318,均值为21.222;207Pb/204Pb=15.581 ~ 15.904,均值为15.747;208Pb/204Pb=39.803 ~ 45.652,均值为42.540。显然,本区硫化物具有极高含量的放射性成因铅,部分放射性成因铅含量稍低的样品与前人所圈定的改造型矿床的硫化物铅同位素范围较为吻合。分析认为,本区硫化物铅同位素代表了两种不同铅源的混合,即早期硫化物的普通铅和围岩中的放射性成因铅。硫铅同位素示踪以及矿相学研究表明,本区早期铜质来源于海底火山喷流-沉积,而晚期富集型铜矿铜质继承了早期铜质,同时也不排除晚期流体中所带来的铜质。 5.流体包裹体研究表明,本区改造型流体中包括三种流体体系:①中-低盐度H2O-NaCl±KCl±FeCl3 ±CaCl2流体,盐度范围为0.53 ~ 24.59 % NaCl equiv.,密度为0.80 ~ 1.16 g/cm3;②高盐度高密度H2O-NaCl±CaCl2流体,盐度为31.2 ~ >59.76% NaCl equiv,密度为1.14 ~ 1.45 g/cm3;③纯液相CO2流体,流体密度为0.77 ~ 1.09 g/cm3。流体包裹体均一温度在100 ~ 456℃之间,主要集中在150 ~ 260℃和260 ~ 456℃两个温度区间。方解石碳、氧同位素范围分别为-5.6 ~ -3.1‰和12.4 ~ 15.5‰。综合分析表明,流体主要来自海底下伏岩浆房的出溶或喷流的高温高盐度流体,部分与海水混合。流体在热液改造过程中活化富集了早期硫化物,经过短距搬运而沉积形成了晚期富集型硫化物。 6.本次研究确定该矿床的成矿机制为:早-中元古代,本区的陆内裂谷作用为火山喷发提供了构造条件,海底火山喷流-沉积形成了早期的贫铜矿胚。元古代末期,本区遭受了强烈的区域变质、变形和流体蚀变改造作用,使原先的贫铜矿胚得到活化富集,形成了工业矿床。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

拉拉铜矿床位于扬子地块西缘的康滇隆起中段,赋存于经历变质的古元古代河口群海相火山-沉积岩系中,是我国重要的受变质热液叠加或改造的火山成因块状硫化物矿床(VHMS)之一,也是四川省最大的铜矿生产基地。本论文以该矿床为研究对象,在系统整理前人资料的基础上,进行了深入细致的野外地质考察和系统采样,选取代表性样品,运用电子探针分析技术、元素地球化学、同位素地球化学(Rb-Sr、Sm-Nd、S)、锆石U-Pb定年等方法手段,对矿区新元古代大规模区域变质作用的变质条件、变质原岩、广泛分布于矿区多个赋矿层位的辉长辉绿岩脉、岩石及矿石性质、硫源、成矿时代等主要岩石学及矿床学问题进行了系统研究,并结合前人研究成果,探讨了矿床的成因机制。论文主要取得以下几点认识: (1)矿区变质火山岩的成岩年龄为1695±20Ma,岩浆在上升侵位的过程中捕获了古元古代早期地壳物质,后期变质改造的时代约为700-800Ma。 (2)基于石榴石黑云母片岩中石榴石黑云母矿物对的电子探针分析数据,利用石榴石-黑云母地质温度计和多硅白云母地质压力计确定了矿区新元古代大规模区域变质作用的变质条件:变质温度为530-580℃,变质压力上限为0.66-0.76GPa,对应于高绿片岩相。 (3)矿区出露的岩石类型以云母片岩类和钠长岩类岩石为主,二者共同构成了矿区的围岩及赋矿岩石,通过对代表性样品的元素地球化学、同位素地球化学研究,采用DF函数判别法、(Al/3-K)-(Al/3-Na)图解法、La/Yb-TR图解法,并结合岩矿鉴定及结构构造特征,恢复了矿区的变质原岩。其中,矿区的云母片岩类样品的变质原岩为沉积岩,以页岩为主,主要来自大陆岛弧及上地壳物质的风化;而钠长岩类样品的变质原岩为火山岩,源自富集地幔,包括“右倾型”钠长岩和“平坦型”钠长岩,前者为分离结晶作用早期并经历一定程度地壳混染的产物,后者主要形成于分离结晶作用晚期,Nb、Ta、Zr、Hf、P、Ti等达到饱和并以副矿物晶出。 (4)综合矿区变质沉积岩及变质火山岩的构造环境判别结果,确定了二者形成于大陆岛弧的弧后盆地环境。 (5)通过对矿区变质火山岩性质、形成机制及硫同位素研究,讨论了矿床中成矿元素可能的富集机制,即地幔中大量的亲铜元素及硫元素进入母岩浆并随之上升形成区域分布的火山岩,为矿床的形成提供了必要条件。 (6)侵入河口群地层并广泛出露于矿区多个赋矿层位的辉长辉绿岩脉的化学成分与板内碱性玄武岩类似且形成于大陆裂谷环境下的类似OIB源区,是高温地幔柱部分熔融的产物,幔源岩浆在上升侵位过程中受到了地壳物质尤其是上地壳物质较小程度的混染,表明新元古代Rodinia超大陆裂解对拉拉地区的成矿作用有重要影响。 (7)拉拉铜矿床主要存在两个成矿期次,即火山喷气-沉积成矿期(1700 Ma左右)和变质热液成矿期(700-800Ma)。矿区主要存在两种类型矿石,即条纹、条带状矿石和块状、浸染状矿石,前者主要赋存于变质火山岩中,可能形成于火山喷气-沉积成矿期,后者主要赋存于变质沉积岩中,可能为变质热液成矿期的产物。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文通过辉长岩在高温、高压下的进变质作用过程的模拟,实现了辉长岩向榴辉岩的转变。在800,2.5Gpa以下,辉长岩生成了石榴石+辉石+长石±尖晶石的矿物组合,在800,2.5Gpa以上,辉长岩则生成石榴+辉石石英的榴辉岩组合。辉长岩向榴辉岩转变过程中存在一个过渡带,过渡带主要的特征是:随压力升高,石榴石逐渐增加,而斜长石逐渐减少。生成的石榴石中,镁铝榴石分子含量随压力的增大而增加,其成因分类属于地幔成因;生成的单斜辉石主要为富镁普通辉石,辉石中硬玉的含量较低。将实验结果与大别山榴辉岩形成条件相比,可以证实:1.大别山榴辉岩形成的温、压条件是在700-900 ℃,2.5Gpa以上;2.大别山柯石英榴辉岩的形成深度至少在80km以上。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本论文选取了斜长角闪岩和榴辉岩作为实验样品,在压力为1.0-3.0 GPa和温度为室温-1300 ℃的条件下,进行了弹性纵波速度和弹性波衰减的实验研究。实验是在YJ-3000吨压力机上进行的,利用超声脉冲透射的方法,首次获得了在压力大于1.0GPa和温度高于800 ℃的条件下的岩石的声波衰减及其各向异性的实验数据。取得如下主要结论:1.榴辉岩的Vp值随压力的升高而增大,在P < 2.0GPa时,上升的速率较快,表明微裂隙逐渐闭合;当P > 2.0GPa时,上升的速率变慢,且表现出很好的线性趋势,这时测得的纵波速度表明了榴辉岩本征的纵波速度,这与前人的实验结果相同。斜长角闪岩的Vp值随压力的变化与榴辉岩的变化相似,不同的是斜长角闪岩的微裂隙闭合压力为1.5GPa。榴辉岩的Vp的Av_p(%)随压力的升高基本保持不变,而斜长角闪岩的Av_p(%)随压力的升高逐渐增大。2.榴辉岩和斜长角闪岩在1.0-3.0 GPa压力下的Vp值随温度的升高而降低,但Vp值在不同的温度阶段,不同的方向上降低的速率和形式不同。如在1.0GPa压力下,当温度小于500 ℃时,Vp值下降较快,说明温度对纵波速度的影响较小;当T > 500 ℃时,Vp值下降的缓慢,说明榴辉岩内部可能发生了结构和应力状态的变化。斜长角闪岩在升温的初始阶段,Vp缓慢下降,并表现出很好的线性趋势。当T > 647 ℃时,Vp下降的速率增大,线性趋势也较好,当T > 1051 ℃时,Vp下降的速率又变小,且比初始时下降的速率要小。榴辉岩Vp的Av_p(%)值随温度的升高而下降,在不同的压力上其下降的速率不同。如在1.0GPa条件下,Av_p(%)随温度的升高而快速下降;在3.0GPa条件下,Av_p(%)值随温度下降缓慢。而斜长角闪岩的Vp的Av_p(%)随温度的变化较复杂,如在1.0GPa条件下,当T < 647 ℃时,Av_p(%)值随温度的升高缓慢增加,当T > 647 ℃时,Av_p(%)值快速增大,当温度达到922 ℃时,Av_p(%)上升到最大值,此后又随温度而减小。3.榴辉岩和斜长角闪岩的弹性波的Q值随压力的升高而增大,其增大的速率和幅度与Vp值的增大形式相同。榴辉岩的Q值的A_Q(%)随压力而升高,而斜长角闪岩的Q值的A_Q(%)随压力基本保持不变。4.榴辉岩和斜长角闪岩的弹性波的Q值随温度的升高而降低,在不同的压力下其降低的速率不同。如在1.0GPa压力下,Q值降低的速率较大;3.0GPa压力下,当T < 300 ℃时,榴辉岩的Q值快速下降,随后下降的幅度减慢,当T > 700 ℃时,榴辉岩的Q值很低,且减小的幅度很小。斜长角闪岩的Q值随温度的变化在1.0-3.0GPa条件下,Q值很小的幅度和趋势相似:当T < 647 ℃时,Q值下降的缓慢,当647 ℃ < T < 1051 ℃时,Q值快速下降,随后下降速率又变小。榴辉岩Q值的A_Q(%)随温度的升高而降低,在1.0和2.0GPa压力下降低较快;3.0GPa压力下A_Q(%)降低较缓慢。斜长角闪岩Q值的A_Q(%)随温度的升高开始缓慢降低,当647 ℃ < T < 105l ℃时,A_Q(%)快速增大,当T > 105l ℃时,A_Q(%)又降低。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

由于对人体健康的危害,氡越来越受到世界各国的广泛关注。经济的发展,使我国地下公共场所大量涌现,但其空气中氡浓度的大规模调查及系统研究还属空白。本论文采取瞬时法(美国SUN公司的1027型连续测氰仪)与累积法(CR一39SSNTD)相结合的测量方法,对我国23个城市的地下工程进行了为期一年的监测,获得了实测数据700多个。在监测的同时,收集了每个测点的各种相关情况资料。论文以内蒙古自治区的呼和浩特、包头、集宁、鄂尔多斯四个城市为例,从环境地球化学角度出发,在研究了各个测点的各种情况之后,探讨了氧在不同类型工程和不同城市的浓度规律。对长期有人在内工作的地下工程内氛所致工作人员的有效剂量当量进行了估算。最后对氨异常的测点进行了原因分析,并提出了地下工程内氰污染的治理和防范措施。本次研究主要得出以下结论:1、地下工程中氰浓度的季节变化规律为:从总平均值看,夏高冬低。与前人对坑道的调查结果一致,与地上氨浓度的变化规律相反。从两季浓度差来看,两季浓度差从大到小依次为:隧道类工程)单建式铜室类工程>结建式嗣室类工程。2、总体来看内蒙三类工程的氰浓度值:隧道类工程)结建式铜室类工程)单建式铜室类工程。不管是单季还是年平均值,各城市三类工程的氧浓度都遵循隧道类.工程远大于结建式铜室工程和单建式铜室工程的规律。通过对结建式桐室工程和单建式铜室工程的对比分析,发现在地下工程内工程上部有无建筑物阻隔,并不是影响氨浓度高低的重要因素,即氰的纵向扩散作用小于横向扩散作用。3、呼和浩特、包头、集宁、鄂尔多斯四个城市的氛浓度年平均值分别为:190Bq/m3、700Bq/m3、190Bq/m3、270Bq/m3。去掉仅有一季结果的侧点值,包头、鄂尔多斯的氨浓度年平均值为:62oBq/m3、250Bq/m3。呼和浩特、包头、集宁、鄂尔多斯四个城市的氛浓度单季值的范围分别为:31-830Bq/m3、57-3500Bq/m3、26一65oBq/m,、64一69OBq/m',;年平均值的范围分别为:39一580Bq/m:'、94一210oBq/m:,、35-460Bq/m3、110-390Bq/m3。呼和浩特、包头、集宁、鄂尔多斯四个城市分别有30.0%、44.4%、33.3%、50.0%的工程年平均氧浓度在200Bq/时以上。四个城市氦浓度的普遍水平:包头)鄂尔多斯)集宁)呼和浩特。4、对所有单建式铜室类地下工程和结建式铜室类工程内工作人员所受剂量当量进行了估算。单建式地下工程内工作人员所受剂量当量的范围是1.247mSv-6.SOgmsv,平均值是2.610Sv。结建式地下工程内工作人员所受剂量当量的范围是1.195Sv-8.531mSv,平均值是2.572mSv。两类地下工程内工作人员所受氨照射剂量当量都很高,有一半的工程剂量当量是地面上公众人员剂量当量0.924mSv的两倍以上。5、不管是从浓度角度还是从剂量估算角度分析,地下工程内的氛水平都比较偏高,需要采取一定防护措施,对现有状况进行改善。6、通风是地下工程防治氡污染最简便易行、见效最快的措施。使用防氡涂料是最经济的措施。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A newly developed polymer coil shrinking theory is described and compared with the existing entangled solution theory to explain electrophoretic migration behaviour of DNA in hydroxypropylmethylcellulose (HPMC) polymer solution in buffer containing 100 mM tris(hydroxymethyl)aminomethane 100 mM boric acid, 2 mm ethylenediaminetetraacetic acid at pH 8.3. The polymer coil shrinking theory gave a better model to explain the results obtained. The polymer coil shrinking concentration, C-s, was found to be 0.305% and the uniform entangled concentration, C+, 0.806%. The existence of three regions (the dilute, semidilute, and concentrated solution) at different polymer concentrations enables a better understanding of the system to guide the selection of the best conditions to separate DNA fragments. For separating large fragments (700/800 bp), dilute solutions (HPMC < 0.3%) should be used to achieve a short migration time (10 min). For small fragments (200/300 bp), concentrated solutions are preferred to obtain constant resolution and uniform separation. The best resolution is 0.6% HPMC due to a combined interaction of the polymer coils and the entangled structure. The possibility of DNA separation in semidilute solution is often neglected and the present results indicate that this region has a promising potential for analytical separation of DNA fragments.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

An industrial scale dehydration process based on hollow fiber membranes for lowering the dew point of natural gas is described in this paper. A pilot test with the feed flux scale of 12x10(4) Nm(3)/d was carried out. Dew points of -8 degreesC-13 degreesC at a gas transport pressure in the pipeline of 4.6M Pa and methane recovery of more than 98% were attained. The water vapor content of the product gas could be maintained around 0.01 vol% during a continuous run of about 700 hours. The effects of feed flux and operation pressure on methane recovery and water vapor content were also investigated. Additionally, some auxiliary technologies, such as a full-time engine using natural gas as fuel and the utilization of vent gas in the process, are also discussed. A small amount of the vent gas from the system was used as a fuel for an engine to drive vacuum pumps, and the heat expelled from the engine was used to warm up the natural gas feed. The whole system can be operated in a self-sustainable manner from an energy point of view, and has a relatively high efficiency in the utilization of natural gas.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Oxygen spillover and back spillover on Pt/TiO2 catalysts have been studied by a potential dynamic sweep method. The characteristics of I-V profiles of Pt/TiO2 electrodes in the three potential sweep regions are different from those of Pt and TiO2 electrodes. The catalytic role of Pt/TiO2 in oxygen spillover and back spillover is identified. It decreases, and the electrochemical oxygen adsorption (or desorption) increases with elevating temperature of hydrogen post-treatment of Pt/TiO2; to a certain extent (hydrogen post-treatment of Pt/TiO2 at 700 degrees C), the control step of oxygen electrode process (anodic oxidation or cathodic reduction) changes from oxygen diffusion to electrochemical oxygen adsorption or desorption, respectively. Increasing the amount of Pt supported on TiO2 enhances the processes of oxygen spillover and back spillover. (C) 1999 Elsevier Science B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

According to the influential dual-route model of reading (Coltheart, Rastle et al. 2001), there are two routes to access the meaning of visual words: one directly by orthography (orthography-semantic) and the other indirectly via the phonology (phonology-semantic). Because of the dramatic difference between written Chinese and alphabetical languages, it is still on debate whether Chinese readers have the same semantic activation processes as readers of alphabetical languages. In this study, the semantic activation processes in alphabetical German and logographic Chinese were compared. Since the N450 for incongruent color words in the Stroop tasks was induced by the semantic conflict between the meaning of the incongruent color words and color naming, this component could be taken as an index for semantic activation of incongruent color words in Stroop tasks. Two cross-script Stroop experiments were adopted to investigate the semantic activation processes in Chinese and German. The first experiment focused on the the role of phonology, while the second one focused on the realative importance of orthography. Cultural differences in cognitive processing between individuals in western and eastern countries have been found (Nisbett & Miyamoto, 2005). In order to exclude potential differences in basic cognitive processes like visual discrimination capabilities during reading, a visual Oddball experiment with non-lexical materials was conducted with all participants. However, as indicated by the P300 elicited by deviant stimuli in both groups, no group difference was observed. In the first Stroop experiments, color words (e.g., “green”), color-word associates (e.g., “grass”), and homophones of color words were used. These words were embedded into color patches with either congruent color (e.g. word “green” in green color patch) or incongruent colors (e.g. word “green” in either red or yellow or blue color patch). The key point is to observe whether homophones in both languages could induce similar behavioral and ERP Stroop effects to that induced by color words. It was also interesting to observe to which extent the N450 was related to the semantic conflicts. Nineteen Chinese adult readers and twenty German adult readers were asked to respond to the back color of these words in the Stroop experiment in their native languages by pressing the corresponding keys. In the behavioral data, incongruent conditions (incongruent color words, incongruent color-word associates, incongruent homophones) had significantly longer reaction times as compared to corresponding congruent conditions. All incongruent conditions in the Geman group elicited an N450 in the 400 to 500 ms time window. In the Chinese group, the N450 in the same time window was also observed for the incongruent color words and incongruent color-word associates. These results indicated that the N450 was very sensitive to semantic conflict-even words with semantic association to colors (e.g. “grass”) could elicite similar N450. However, the N450 was absent for incongruent homophones of color words in the Chinese group. Instead, in a later time window (600-800 ms), incongruent homophones elicited a positivity over left posterior regions as compared to congruent homophones. Similar positivity was also observed for color words in the 700 to 1000 ms time window in the Chinese group and 600 to 1000 ms time window for incongruent color words and homophones in the Geman group. These results indicate that phonology plays an important role in Geman semantic activation processes, but not in Chinese. In the second Stroop experiment, color words and pseudowords which had similiar visual shape to color words in both languages were used as materials. Another group of eighteen Chinese and twenty Germans were involved in the Stroop experiment in their native languages.The ERPs were recorded during their performance. In the behavioral data, strong and comparable Stroop effects (as counted by substract the reaction times in the congruent conditions from reaction times in the incongruent conditions) were observed. In the ERP data, both incongruent color words and incongruent pseudowords elicited an N450 over the whole brain scalp in both groups. These results indicated that orthography played an equally important role in semantic activation processes in both languages. The results of the two Stroop experiments support the view that the semantic activation process in Chiense readers differs significantly from that in German readers. The former rely mainly on the direct route (orthography-semantic), while the latter use both direct route and incirect route (phonology-semantic). These findings also indicate that the characteritics of different languages shape the semantic activation processes.