检索结果-南通市图书馆

Dehydration at subduction zones and the geochemistry of slab fluids

Science China Earth Sciences 2020年第12期63卷 1925-1937页

作者： wancai li Huaiwei Ni CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei230026China CAS Center for Excellence in Comparative Planetology Hefei230026China

Subducting oceanic slabs undergo metamorphic dehydration with the increase of temperature and pressure during *** is an essential step for element recycling,and slab fluids are critical agents for mediating slab-mantle *** is mainly controlled by the thermal structure of subduction zones and the stability of hydrous *** fore-arc depths,slab dehydration produces aqueous fluid with dissolved salts such as *** subduction proceeds deeper,the content of silicate components *** sub-arc and post-arc depths,a hydrous silicate melt is likely to form,or a supercritical fluid could arise from complete miscibility between silicates and H_(2)*** partitioning of elements between slab fluid and the residual solid rock is controlled by the type of fluid,and generally it is the supercritical fluid that is the most capable of mobilizing trace elements,being an effective carrier even for high field strength *** the chemistry of slab fluids relies on sophisticated integration of experiments,theoretical computation and investigation of natural rock *** contribution focuses on the content and speciation of key volatiles,including carbon,nitrogen and sulfur,in slab fluids as well as important fluid properties such as oxygen fugacity and *** properties of slab fluids show complicated variation under the control of mineral assemblages and T-P *** fluids at great depths of subductions have been inferred to be modestly alkaline and not necessarily very oxidizing as often *** progress in the research of slab dehydration and the chemistry and properties of slab fluids demands urgently the development of innovative experimental and computational technology including in situ analytical methods at high T-P.

关键词： Subduction zone Dehydration Slab fluids Volatiles Oxygen fugacity Acidity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Giant enhancement of photoluminescence quantum yield in 2D perovskite thin microplates by graphene encapsulation

引用

Nano Research 2021年第6期14卷 1980-1984页

作者： wancai li Jiaqi Ma Xue Cheng Dehui li School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan430074China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan430074China

The optoelectronic performances of the layered materials are strongly dependent on the thickness of the samples due to the surface *** the size of the samples decreases to few nanometers,the surface depletion field and surface defect density are prominent arising from the large surface to volume *** instance,thin two-dimensional(2D)organic-inorganic hybrid perovskite microplates usually exhibit a rather low photoluminescence quantum yield(PLQY),owning to the strong surface ***,we report that the PLQY can be enhanced as large as 28 times in(iso-BA)2Pbl4(BA=C4H9NH3)2D perovskite thin microplates encapsulated by graphene,resulting in that the PLQY is more than 18%for the microplate with a thickness of 6.7 nm at 78 *** the thickness of the 2D perovskite microplate increases,the enhancement is gradually reduced and finally *** observation is in striking contrast to that in monolayer transition metal dichalcogenides(TMDs),when the PLQY is quenched by covering a layer of graphene due to the efficient charge *** enhancement of PLQY in 2D perovskites can be mainly ascribed to the reduced quantum confined Stark effect(QCSE)due to the reduced surface depletion field after covering graphene flake,resulting in the enhanced radiative recombination *** findings provide a cost-effective approach to enhance the luminescence,which may pave the way toward high performance light emitting devices based on 2D perovskites.

关键词： two-dimensional perovskite photoluminescence quantum yield quantum confinement surface depletion field

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Methodological progress in trace amounts of structural water in nominally anhydrous minerals

引用

Science China Earth Sciences 2016年第5期59卷 901-909页

作者： SHENG YingMing GONG Bing li wancai XIA Mei CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space Sciences University of Science and Technology of China

In the deep Earth, hydrogen mainly occurs as structural hydroxyl and molecular water in minerals and melts, constituting mobile and immobile aqueous components. Hydrous minerals contain hydrogen which occupies a specific structural position and constitutes an indispensable component of chemical formulae. On the other hand, nominally anhydrous minerals do not contain hydrogen in their chemical formulae, but can host trace amounts of water in structural position and lattice defect. The molecular water may occur in the lattice defect as fluid/melt inclusions in minerals. Even though the water content of nominally anhydrous minerals is very limited generally in the order of ppm(parts per million), they may play a significant role in influencing the physicochemical properties of mineral and rock systems. With the continuous improvement of modern instrumentations, the analytical methodology exhibits trends for higher spatial resolution, lower detection limit and integral multiple methods on the water amount and its isotopic ratio. Among these methods, Fourier transform infrared spectrometry remains the most widely used, while secondary ion mass spectrometry, continuous flow mass spectrometry, elastic recoil detection analysis and Raman spectrometry are promising. This paper provides a brief review on the methodological progress and their applications to the analysis of structural water in nominally anhydrous minerals.

关键词： Nominally anhydrous minerals Water content Structural hydroxyl Molecular water Fourier transform infrared spectrometry

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Surface depletion field in 2D perovskite microplates: Structural phase transition, quantum confinement and Stark effect

引用

Nano Research 2019年第11期12卷 2858-2865页

作者： wancai li Chen Fang Haizhen Wang Shuai Wang Junze li Jiaqi Ma Jun Wang Hongmei Luo Dehui li School of Optical and Electronic Information and Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan430074China Department of Chemical and Materials Engineering New Mexico State UniversityLas CrucesNM88003USA

Surface depletion field would introduce the depletion region near surface and thus could significantly alter the optical,electronic and optoelectronic properties of the materials,especially low-dimensional ***-dimensional(2D)organic—inorganic hybrid perovskites with van der Waals bonds in the out-of-plane direction are expected to have less influence from the surface depletion field;nevertheless,studies on this remain *** we report on how the surface depletion field affects the structural phase transition,quantum confinement and Stark effect in 2D(BA)2PbI4 perovskite microplates by the thickness-,temperature-and power-dependent photoluminescence(PL)*** dependent PL studies suggest that high-temperature phase(HTP)and low-temperature phase(LTP)can coexist in a wider temperature range depending on the thickness of the 2D perovskite *** the decrease of the microplate thickness,the structural phase transition temperature first gradually decreases and then increases below 25 nm,in striking contrast to the conventional size dependent structural phase *** on the thickness evolution of the emission peaks for both high-temperature phase and low-temperature phase,the anomalous size dependent phase transition could probably be ascribed to the surface depletion field and the surface energy difference between *** explanation was further supported by the temperature dependent PL studies of the suspended microplates and encapsulated microplates with graphene and boron nitride *** with the thickness dependent phase transition,the emission energies of free excitons for both HTP and LTP with thickness can be ascribed to the surface depletion induced confinement and Stark effect.

关键词： two-dimensional(2D)perovskite thickness surface depletion field structural phase transition quantum confinement Stark effect

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Optimization and Implementation of the Sobel Edge Detection on Davinci Platform

Optimization and Implementation of the Sobel Edge Detection ...

引用

2013年中国智能自动化学术会议

作者： wancai li Zekun liu Zhiwei Tang The Third Research Institute of Public Security of P.R.C

Sobel is one of the best edge detection ***,it often loses some textural information when complex image is *** paper mainly discusses how to improve the shortcomings of Sobel and optimize the filtering,templates,and noise algorithms for edge *** the optimization, the paper presents the implementation of edge detection on Davinci platform. The algorithm code has been optimized which based on the TMS320DM6446 dual-core *** operations have been split into the shift and add operations through integration algorithm engine which use the DSP’s pipelining *** the test experiment on Davinci platform,it can work *** method can not only provide the possibility of the real-time image processing,but also eliminate the impact of noise,and enhance the detection accuracy.

关键词： Davinci DSP Sobel Image processing Edge detection

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Circularly polarized light emission and detection by chiral inorganic semiconductors

引用

Frontiers of Optoelectronics 2024年第2期17卷 43-49页

作者： Zha li wancai li Dehui li Wei Tang Huageng liang Huaibing Song Chao Chen liang Gao Jiang Tang Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China International Health Care Center National Center for Global Health and MedicineTokyo 162‑8655Japan Hepato‑Biliary‑Pancreatic Surgery Division Department of SurgeryThe University of Tokyo HospitalTokyo 113‑8655Japan Department of Urology Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430074China Faculty of Materials Science and Chemistry China University of GeosciencesWuhan 430074China

Chiral inorganic semiconductors with high dissymmetric factor are highly desirable,but it is generally difficult to induce chiral structure in inorganic semiconductors because of their structure rigidity and *** this study,we introduced chiral ZnO film as hard template to transfer chirality to CsPbBr_(3) film and PbS quantum dots(QDs)for circularly polarized light(CPL)emission and detection,*** prepared CsPbBr_(3)/ZnO thin film exhibited CPL emission at 520 nm and the PbS QDs/ZnO film realized CPL detection at 780 nm,featuring high dissymmetric factor up to around *** electron transition based mechanism is responsible for chirality transfer.

关键词： High dissymmetric factor Circularly polarized light emission Semiconductor Hard template,Chirality

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Formation and evolution of supercritical geofluid

引用

Science China Earth Sciences 2024年

作者： Huaiwei NI Yilin XIAO Xiaolin XIONG Xiandong liU Chunxiao GAO Yixiang CHEN Yunguo li wancai li Xuan GUO Yangyang WANG Dongbo TAN li ZHANG State Key Laboratory of lithospheric and Environmental Coevolution University of Science and Technology of China Deep Space Exploration Laboratory/School of Earth and Space Sciences University of Science and Technology of China Guangzhou Institute of Geochemistry Chinese Academy of Sciences School of Earth Sciences and Engineering Nanjing University State Key Lab of Superhard Materials Jilin University

In this work, we provide a comprehensive review on the formation, evolution, properties, and effects of supercritical geofluid. In Earth's interior, enhanced miscibility between H2O and silicate by the addition of special components or by the increase of pressure and temperature gives rise to supercritical geofluid with a significant amount of both H2O and silicate *** formation of supercritical geofluid in magmatic-hydrothermal systems, typified by pegmatite system, is governed by meltfluid critical curve. The formation of supercritical geofluid in metamorphic systems, typified by subducted slab, is governed by the second critical end point. Experimental results suggest that the presence of boron and fluorine in pegmatite system makes it possible to form supercritical geofluid at crustal depths, but the release of supercritical geofluid from subducted slab is withheld until almost 100 km depth. A major presence of both H2O and depolymerized structural units（monomers, dimers, etc.） endows supercritical geofluid with unique physical properties including low density, low elastic moduli, low viscosity, high diffusivity,and high electrical conductivity. Supercritical geofluid can effectively mobilize a variety of elements even including high field strength elements and heavy rare earth elements. The chemical signatures of supercritical geofluid can be inherited by metasomatized mantle and mantle-derived melts, and this could give an explanation of the oxidation of arc magmas. Phase separation of supercritical geofluid through the mechanism of spinodal decomposition leads to formation of a melt network. Multiphase fluid inclusions recovered from subduction zone rocks and pegmatites are possible relics of supercritical geofluid. Supercritical geofluid can cause electrical anomaly and low seismic velocity near the top of subducted slab, and can be linked with intermediate-focus earthquakes. Supercritical geofluid may have played a crucial role in the formation of pe

关键词：

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

不同功能区林下土壤多环芳烃分布特征及来源分析

引用

森林与环境学报 2020年第2期40卷 140-148页

作者：李万才李吉玫张毓涛师庆东新疆大学资源与环境科学学院新疆乌鲁木齐830046 新疆林业科学院森林生态研究所新疆乌鲁木齐830002 新疆天山森林生态系统国家定位观测研究站新疆乌鲁木齐830063

以乌鲁木齐工业区、交通区、居民区和公园区的林带作为试验采样区,分别从各功能区林带土壤中多环芳烃(PAHs)的含量、组成、污染情况、来源4个方面,分析了土壤中16种PAHs污染特征。结果表明:乌鲁木齐不同功能区林下土壤平均PAHs的含量为(... 详细信息

以乌鲁木齐工业区、交通区、居民区和公园区的林带作为试验采样区,分别从各功能区林带土壤中多环芳烃(PAHs)的含量、组成、污染情况、来源4个方面,分析了土壤中16种PAHs污染特征。结果表明:乌鲁木齐不同功能区林下土壤平均PAHs的含量为(375.76±32.96)ng·g^-1,其中交通区>工业区>居民区>公园区。低环和高环PAHs含量分别占32.02%和67.98%。工业区林带和交通区林带土壤以4环和3环为主,居民区和公园区以5环为主。工业区和交通区林带土壤以轻度污染为主(42.90%和37.50%);而公园区和居民区以轻度污染(60.00%和66.67%)和未污染(40.00%和33.33%)为主。工业区林带土壤组分中占比最高和最低的分别是茚并(1,2,3-cd)芘(IcdP)占16.01%和?(Chr)占0.98%,交通区林带占比最高和最低的分别是荧蒽(Fla)占16.01%和苊(Ace)占0.49%,居民区林带分别是荧蒽(Fla)占15.66%和?(Chr)占0.21%,公园区林带分别是茚并(1,2,3-cd)芘(IcdP)占19.48%和?(Chr)占0.84%。以煤、木、草等生物质燃烧为污染源的样地最多的是公园区;以汽车尾气、石油燃烧为污染源的样地最多的是交通区。各功能区PAHs的来源主要为煤、生物质等的不完全燃烧。

关键词：乌鲁木齐城市森林林带多环芳烃分布特征来源

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

砂岩中绿泥石包膜与岩石润湿性及岩电参数的关系研究

引用

石油物探 2020年第4期59卷 647-654页

作者：张丽华潘保芝王云梅郭宇航李万才王敏吉林大学地球探测科学与技术学院吉林长春130026 中国石油化工股份有限公司东北油气分公司吉林长春130026

对复杂润湿性砂岩储层研究发现,绿泥石包膜的存在会导致岩石润湿性表现为亲油,并且这种润湿性不受洗油洗盐过程的影响。龙凤山地区营城组砂岩中广泛发育自生绿泥石包膜,岩电测量发现,在洗油洗盐后部分岩样的饱和度指数(n)值依然很高,最... 详细信息

对复杂润湿性砂岩储层研究发现,绿泥石包膜的存在会导致岩石润湿性表现为亲油,并且这种润湿性不受洗油洗盐过程的影响。龙凤山地区营城组砂岩中广泛发育自生绿泥石包膜,岩电测量发现,在洗油洗盐后部分岩样的饱和度指数(n)值依然很高,最高达到14.57,同时胶结指数(m)值较低,m与n之间有较好的线性关系。研究认为这种m值偏低、n值偏高的原因是绿泥石包膜改变了岩石的润湿性,从而导致岩电参数的变化。对7块岩样进行了粘土和全岩分析,建立了绿泥石含量与m,n的关系,分析了绿泥石包膜对岩石导电性的影响机制,并从物源上对绿泥石及m,n的平面分布进行了解释。该研究为采用电测井方法评价复杂润湿性储层的含水饱和度提供了岩石物理基础,对岩石导电机制的进一步认识和提高此类砂岩的测井解释精度有一定的参考价值。

关键词：绿泥石包膜润湿性岩电参数平面分布电测井方法营城组砂岩龙凤山

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

BST系列全自动网版印刷机

引用

丝网印刷 2006年第12期 18-20页

作者：李镇炯吴家昌李万才

介绍了一种使用UV油墨的新型全自动网版印刷机,放料、套印、干燥、裁切等工序可联机完成。详细介绍了其工作原理、设备功能及流程控制。

关键词：网印机 UV油墨全自动

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：