检索结果-南通市图书馆

Inter-facet composition modulation of III-nitride nanowires over pyramid textured Si substrates by stationary molecular beam epitaxy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

nano Research 2021年第5期14卷 1502-1511页

作者： Peng wang Hedong Chen Hao wang Dan.wang Changkun Song Xingyu wang Hongjie Yin Lujia Rao Guofu Zhou richard nötzel Guangdong Provincial Key Laboratory of Optical Information Materials and Technology South China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou510006China national Center for International Research on Green Optoelectronics South China Normal UniversityGuangzhou510006China Department of Physics Xiamen UniversityXiamen361005China Analysis&Testing Center South China Normal UniversityGuangzhou510631China Academy of Shenzhen Guohua Optoelectronics Shenzhen518110China

InGan nanowires (nWs) are grown on pyramid textured Si substrates by stationary plasma-assisted molecular beam epitaxy (PA-MBE). The incidence angles of the highly directional source beams vary for different pyramid facets, inducing a distinct inter-facet modulation of the In content of the InGan nWs, which is verified by spatial element distribution analysis. The resulting multi-wavelength emission is confirmed by photoluminescence (PL) and cathodoluminescence (CL). Pure Gan phase formation dominates on certain facets, which is attributed to extreme local growth conditions, such as low active n flux. On the same facets, InGan nWs exhibit a morphology change close to the pyramid ridge, indicating inter-facet atom migration. This cross-talk effect due to inter-facet atom migration is verified by a decrease of the inter-facet In content modulation amplitude with shrinking pyramid size. A detailed analysis of the In content variation across individual pyramid facets and element distribution line profiles reveals that the cross-talk effect originates mainly from the inter-facet atom migration over the convex pyramid ridge facet boundaries rather than the concave base line facet boundaries. This is understood by first-principles calculations showing that the pyramid baseline facet boundary acts as an energy barrier for atom migration, which is much higher than that of the ridge facet boundary. The influence of the growth temperature on the inter-facet In content modulation is also presented. This work gives deep insight into the composition modulation for the realization of multi-color light-emitting devices based on the monolithic growth of InGan nWs on pyramid textured Si substrates.

关键词： pyramid textured Si substrate composition modulation III-nitride nanowire molecular beam epitaxy stationary growth cross talk

Inn/InGan quantum dot electrochemical devices:new solutions for energy and health

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

national Science Review 2017年第2期4卷 184-195页

作者： richard ntzel South China Academy of Advanced Optoelectronics South China Normal University L-nESS and Dipartimento di Scienza dei Materiali Università di Milano-Bicocca

A review is given of the exceptional electrochemical performance of epitaxial Inn/InGan quantum dots(QDs) as photoelectrodes for solar hydrogen generation by water spliting, as biosensor transducers and as anion-selective electrodes, and they are also evaluated as supercapacitor electrodes. he performance is benchmarked against the best performances of other reported materials and nanostructures. A model based on the unique interplay of surface and quantum properties is put forward to understand the boost of catalytic activity and anion selectivity interlinking quantum nanostructure physics with electrochemistry and catalysis. Of equal impact is the direct growth on cheap Si substrates without any bufer layers, allowing novel device designs and integration with Si technology. his makes the Inn/InGan QDs viable, opening up new application ields for Ⅲ-nitride semiconductors.

关键词： quantum dot solar hydrogen biosensor ion-selective electrode supercapacitor Inn InGan

Treatability aspects of urban stormwater stressors

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2012年第5期6卷 631-637页

作者： Anthony n. TAFURI richard FIELD national Risk Management Research Laboratory Water Supply and Water Resources Division Urban Watershed Management Branch U.S. Environmental Protection Agency Edison NJ 08837-3679 USA

Pollution from diffuse sources （pollution from contaminants picked up and carried into surface waters by stormwater runoff） has been identified as a significant source of water quality problems in the U.S. scientists and engineers continue to seek solutions that will allow them to optimize existing technologies and develop new ones that will provide the best possible protection to people, wildlife, and the environment. This paper addresses the various pollutants or stressors in urban stormwater, including flow （shear force）, pathogens, suspended solids/sediment, toxicants （organic and metals）, nutrients, oxygen demanding substances, and coarse solids. A broad overview of the pollutants removed and the removal mechanisms by and of conventional best management practices （BMPs） is also presented. The principal treatment mechanisms of conventional wet ponds, vegetative swales/ buffer strips, and wetlands are sedimentation and filtration. These mechanisms have the capability to remove sig- nificant amounts of suspended solids or particulate matter and are a vital component of strategies to reduce pollutant loads to receiving waters. In addition, because most of the nation＇s receiving water violations are caused by pathogen indicator bacteria, it is of utmost importance that research efforts address this problem. Further research is also needed on the treatment of emerging contaminants in BMPs and on the costs and affects of maintenance and maintenance schedules on the long-term performance of BMPs.

关键词： stormwater wet weather flow urban runoff

Telecentres in Mountain Regions-A Peruvian Case Study of the Impact of Information and Communication Technologies on Remoteness and Exclusion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2009年第4期6卷 320-330页

作者： richard Heeks Laura León Kanashiro Centre for Development Informatics Arthur Lewis BuildingUniversity of Manchester

Communities in developing country mountain areas,in part due to their remoteness,find themselves excluded from social,political and economic systems; and excluded from access to resources. This paper aims to study the impact of information and communication technologies (ICTs) on remoteness and exclusion. It utilises two models - the resource movement framework,and the "information chain" - to analyse a telecentre in one district of mountainous Huancavelica,Peru's poorest region,set in the high Andes. It finds ICTs enabling new and positive resource flows for the two key user groups:teenaged school students and young farmers. These help to maintain social networks. They also support information searches that have improved agricultural practice where other information chain resources have been available. But non-use and ineffective use of the telecentre are found where information chain resources are lacking. ICTs have some impacts on intangible elements of remoteness. In this particular example,they also offer access to some previously-excluded resources. But they have not really addressed the systematic exclusions faced by mountain communities. And they so far appear to be a technology of inequality; favouring those residents who begin with better resource *** paper concludes by offering some recommendations for mountain ICT project practice.

关键词： Exclusion Telecentre Information and communication technologies (ICTs) new technology Andes Peru

Trees of Panama: A complete checklist with every geographic range

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2020年第3期7卷 526-538页

作者： richard Condit Salomón Aguilar Rolando Pérez Morton Arboretum 4100 Illinois Rte.53Lisle60532ILUSA Smithsonian Tropical Research Institute Panama CityPanama

Background Central America is one of the most diverse floristic provinces in the world,but comprehensive plant lists for the region are incomplete and need frequent *** geographic ranges of individual species are seldom *** detailed forest inventory plots of Panama thus lack a global geographic *** order to provide one,we assembled a thoroughly vetted checklist of all tree species of Panama,along with an estimate of each one’s range size based on published specimen *** 1)Panama has 3043 tree species in 141 families and 752 genera;57.6%were≥10 m tall and 16.9%were 3-5 m tall.2)The widest ranges were>1.5×107 km2,covering the entire neotropics and reaching>30∘latitude;12.4%of the species had ranges exceeding 107 *** median range was 6.9×105 km2.3)At the other extreme,16.2%of the species had a rangen suggesting endangered status.4)Range size increased with a tree species’height and varied significantly among families.5)Tree census plots,where we mapped and measured all individuals,captured 27.5%of the tree species,but a biased selection relative to range size;only 4.5%of the species in plots had rangesnama,based on rigorous criteria aimed at matching plot censuses,is 20%larger than *** recording species’maximum heights,we allow comparisons with other regions based on matching definitions,and the range sizes provide a quantitative basis for assessing extinction *** next goal is to merge population density from plot censuses to add rigor to predictions of extinction risk of poorly-studied tropical tree species.

关键词： red Trees of Panama A complete checklist with every geographic range

From 2-dimensional to 3-dimensional: Overcoming dilemmas in intestinal mucosal interpretation

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2019年第20期25卷 2402-2415页

作者： richard PG Charlesworth Michael n Marsh School of Science and Technology University of New EnglandArmidaleNSW 2351Australia Wolfson College University of OxfordOxford OX2 6UDUnited Kingdom

The purpose of this review is to provide a definitive account of small intestinal mucosal structure and interpretation. The coeliac lesion has been well known, but not well described to date and this review aims to identify the interpretative difficulties which have arisen over time with the histological assessment of coeliac disease. In early coeliac interpretation, there were significant inaccuracies, particularly surrounding intraepithelial lymphocyte counts and the degree of villous flattening which occurred in the tissue. Many of these interpretive pitfalls are still encountered today, increasing the potential for diagnostic errors. These difficulties are mostly due to the fact that stained 2-dimensional sections can never truly represent the 3-dimensional framework of the intestinal tissue under investigation. Therefore, this review offers a critical account occasioned by these 2-dimensional interpretative errors and which, in our opinion, should in general be jettisoned. As a result, we leave a framework regarding the true 3-dimensional knowledge of mucosal structure accrued over the 70-year period of study, and one which is available for future reference.

关键词： Coeliac disease Histology Diagnosis 2-dimensional 3-dimensional

Long-term economic sensitivity analysis of light duty underground mining vehicles by power source

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2017年第3期27卷 567-571页

作者： Schatz richard S. nieto Antonio Lvov Serguei n. The EMS Energy Institute College of Earth and Mineral Engineering The Pennsylvania State University State College PA 16802 USA Department of Energy and Mineral Engineering College of Earth and Mineral Engineering The Pennsylvania State University State College PA 16802 USA Department of Materials Science and Engineering College of Earth and Mineral Engineering The Pennsylvania State University State College PA 16802 USA

LHD's are expensive vehicles; therefore, it is important to accurately define the financial consequences associated with the investment of purchasing the mining equipment. This study concentrates on longterm incremental and sensitivity analysis to determine whether it is feasible to incorporate current battery technology into these machines. When revenue was taken into account, decreasing the amount of haulage in battery operated equipment by 5% or 200 kg per h amounts to a $4.0 × 10~4 loss of profit per year. On average it was found that using battery operated equipment generated $9.5 × 10~4 more in income annually, reducing the payback period from seven to two years to pay back the additional $1.0 × 10~5 investment of buying battery powered equipment over cheaper diesel equipment. Due to the estimated 5% increase in capital, it was observed that electric vehicles must possess a lifetime that is a minimum of one year longer than that of diesel equipment.

关键词： Sensitivity analysis Underground mining vehicles Battery power Battery mining equipment Economic evaluation

Varicella zoster meningitis complicating combined anti-tumor necrosis factor and corticosteroid therapy in Crohn's disease

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2013年第21期19卷 3347-3351页

作者： Christopher Ma Brennan Walters richard n Fedorak Division of Gastroenterology University of AlbertaEdmontonAL T6G 2X8Canada

Opportunistic viral infections are a well-recognized complication of anti-tumor necrosis factor (TnF) therapy for inflammatory bowel disease (IBD). Cases of severe or atypical varicella zoster virus infection, both primary and latent reactivation, have been described in association with immunosuppression of Crohn's disease (CD) patients. However, central nervous system varicella zoster virus infections have been rarely described, and there are no previous reports of varicella zoster virus meningitis associated with anti-TnF therapy among the CD population. Here, we present the case of a 40-year-old male with severe ileocecal-CD who developed a reactivation of dermatomal herpes zoster after treatment with prednisone and adalimumab. The reactivation presented as debilitating varicella zoster virus meningitis, which was not completely resolved despite aggressive antiviral therapy with prolonged intravenous acyclovir and subsequent oral valacyclovir. This is the first reported case of opportunistic central nervous system varicella zoster infection complicating anti-TnF therapy in the CD population. This paper also reviews the literature on varicella zoster virus infections of immunosuppressed IBD patients and the importance of vaccination prior to initiation of anti-TnF therapy.

关键词： Varicella zoster virus Meningitis Crohn’s disease Adalimumab Infliximab corticosteroids Antitumor necrosis factor

novel design concepts for network intrusion systems based on dendritic cells processes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University 2013年第8期20卷 2175-2185页

作者： richard M R 谭冠政 OnGALO P n F CHERUIYOT W School of Information Science and Engineering Central South University

An abstraction and an investigation to the worth of dendritic cells (DCs) ability to collect, process and present antigens are presented. Computationally, this ability is shown to provide a feature reduction mechanism that could be used to reduce the complexity of a search space, a mechanism for development of highly specialized detector sets as well as a selective mechanism used in directing subsets of detectors to be activated when certain danger signals are present. It is shown that DCs, primed by different danger signals, provide a basis for different anomaly detection pathways. Different antigen-peptides are developed based on different danger signals present, and these peptides are presented to different adaptive layer detectors that correspond to the given danger signal. Experiments are then undertaken that compare current approaches, where a full antigen structure and the whole repertoire of detectors are used, with the proposed approach. Experiment results indicate that such an approach is feasible and can help reduce the complexity of the problem by significant levels. It also improves the efficiency of the system, given that only a subset of detectors are involved during the detection process. Having several different sets of detectors increases the robustness of the resulting system. Detectors developed based on peptides are also highly discriminative, which reduces the false positives rates, making the approach feasible for a real time environment.

关键词： artificial immune systems network intrusion detection anomaly detection feature reduction negative selectionalgorithm danger model