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Effect of high anodic polarization on the passive layer properties of superduplex stainless steel friction stir welds at different chloride electrolyte pH values and temperatures

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International Journal of minerals,metallurgy and materials 2019年第6期26卷 710-721页

作者： L.A.Santa-Cruz G.machado A.A.Vicente t.f.C.Hermenegildo t.f.A.Santos Department of mechanical Engineering Universidade Federal de PernambucoAv.da Arquiteturas/n50740-550RecifePEBrazil Center of nanotechnology Centro de Tecnologias Estratégicas do NordesteCETENERecifePEBrazil Department of Chemical Engineering Universidade de Sao PauloSao PauloSPBrazil

the conditions used for friction stir welding of duplex stainless steels determine the resulting mechanical and corrosion performance of the *** study investigates the corrosion resistance of UnS S32750 and S32760 superduplex stainless steels(SDSSs)joined by friction stir welding,employing cyclic polarization,mott–Schottky,and microscopy techniques for *** microscopy images indicated the presence of a deleterious intermetallic phase after electrolytic etching of S32760,as well as decreased corrosion *** presence of molybdenum in the steels promoted better passive behavior at low *** mott–Schottky curves revealed p-n heterojunction behavior of the passive *** acquired after the polarization test by scanning electron microscopy showed higher passivation propensity with increases of temperature and pH.

关键词： superduplex stainless steel friction stir welding corrosion resistance cyclic polarization mott–Schottky

Evolving role of endoscopy in inflammatory bowel disease:Going beyond diagnosis

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World Journal of Gastroenterology 2021年第20期27卷 2521-2530页

作者： Paulina núñez f noa Krugliak Cleveland Rodrigo Quera David t Rubin Department of Gastroenterology Inflammatory Bowel Disease ProgramClinica Universidad de los AndesSantiago 7620157RMChile Department of Gastroenterology Hospital San Juan de DiosSantiago 8350488RMChile University of Chicago medicine Inflammatory Bowel Disease Center ChicagoIL 60637United States

Inflammatory bowel disease,encompassing Crohn’s disease(CD)and ulcerative colitis,are chronic immune-mediated inflammatory bowel diseases(IBD)that primarily affect the gastrointestinal tract with periods of activity and *** body of evidence exist to strengthen the prognostic role of endoscopic evaluation for both disease activity and severity and it remains the gold standard for the assessment of mucosal *** healing has been associated with improved clinical outcomes with prolonged remission,decreased hospitalization,IBD-related surgeries and colorectal cancer ***,endoscopic objectives in IBD have been incorporated as part of standard *** the known increased risk of colorectal cancer in IBD,although prevention strategies continue to develop,regular surveillance for early detection of neoplasia continue to be paramount in IBD patients’*** is thanks to evolving technology and visualization techniques that surveillance strategies are continuously *** endoscopic options in IBD have also been expanding,from surgery sparing therapies such as balloon dilation of fibrostenotic strictures in CD to endoscopic mucosal resection of neoplastic *** this review article,we discuss the current evidence on the use of endoscopy as part of standard of care of IBD,its role in surveillance of neoplasia,and the role of interventional endoscopic therapies.

关键词： Inflammatory bowel disease Endoscopy Crohn’s disease Ulcerative colitis therapeutic endoscopy Surveillance

mobility of large clusters on a semiconductor surface:Kinetic monte Carlo simulation results

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Chinese Physics B 2016年第1期25卷 580-584页

作者： m Esen A t ttizemen m Ozdemir Vocational School of Adana Cukurova UniversityAdana O1160Turkey Department of Science and mathematics Education Faculty of EducationCumhuriyet UniversitySivas 58140Turkey Department of Physics Cukurova UniversityAdana 01330Turkey

the mobility of clusters on a semiconductor surface for various values of cluster size is studied as a function of temperature by kinetic monte Carlo method. the cluster resides on the surface of a square grid. Kinetic processes such as the diffusion of single particles on the surface, their attachment and detachment to/from clusters, diffusion of particles along cluster edges are considered. the clusters considered in this study consist of 150-6000 atoms per cluster on average. A statistical probability of motion to each direction is assigned to each particle where a particle with four nearest neighbors is assumed to be immobile. the mobility of a cluster is found from the root mean square displacement of the center of mass of the cluster as a function of time. It is found that the diffusion coefficient of clusters goes as D = A（t）na where n is the average number of particles in the cluster, A（t） is a temperature-dependent constant and a is a parameter with a value of about -0.64 〈 a 〈 -0.75. the value of a is found to be independent of cluster sizes and temperature values （170-220 K） considered in this study. As the diffusion along the perimeter of the cluster becomes prohibitive, the exponent approaches a value of -0.5. the diffusion coefficient is found to change by one order of magnitude as a function of cluster size.

关键词： diffusion constant cluster mobility monte Carlo method

Sintering formation of Low temperature Phase mnBi and Its Disordering in mechanical milling

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Journal of materials Science & technology 1996年第5期12卷 335-341页

作者： Yin, fX Gu, nJ Shigematsu, t nakanishi, n KOnAn UnIV FAC SCIDEPT CHEMKOBE 658JAPAN

With X-ray diffraction and DSC analysis, it is found that 4 cycles of sintering at 593 K are necessary for the complete production of the low-temperature phase (LtP) mnBi. the c/a of the fabricated LtP mnBi is 1.4286. metastable phase mnBip formed in primary sintering stage of LtP mnBi has the similar crystal structure and lattice constant with the quenched high-temperature phase (HtP) mn1.08Bi. the structural differences between mnBip phase and mn1.08Bi phase are discussed. the LtP mnBi phase is unstable for strong mechanical milling as Bi appears after milling over 7200 s in the present milling condition. Strains caused by the mechanical attrition are difficult to accumulate in the mnBi crystals, and the crystal size of the milled mnBi is only 30 nm before the presence of grains coalescence. the whole milling process can be classified into 3 stages indicated by the structural changes. Based on the structural parameter calculation, the changes of atomic configurations in every stage have been discussed. the existence of Bi equivalent vacancy site is considered to play an important role in the disordering processes of mn and Bi atoms.

关键词： Binary alloys

Plinthite and Its Associated Evolutionary forms in Soils and Landscapes:A Review

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Pedosphere 2014年第2期24卷 153-166页

作者： P.n.EZE t.K.UDEIGWE m.E.mEADOWS Department of Environmental & Geographical Science University of Cape Town Department of Plant and Soil Science Texas Tech University

At elevated temperature regimes and abundant precipitation, mobilization and accretion of weathered iron oxides are promoted especially in a reduced environments in the tropics. this may lead to the formation of plinthite, which hardens irreversibly upon repeated wetting and drying to form petroplinthite. the need for this review stems from the seemingly dearth of information on the subject and a need to clarify different terms used in describing plinthite. We review various research works on plinthite and its associated pedogenic forms in the tropics. furthermore, we proffer recommendations as to the most appropriate land use management practices that could help minimise the environmental and agronomic problems associated with plinthite and its related pedogenic forms. Parent material, temperature, seasonality and geomorphology are critical factors that influence soil water regime which in turn affect the pedogenesis of plinthite. Soil pH and mineralogy are additional factors that could also promote plinthite formation. fossil plinthic soils are potential proxies for palaeoenvironmental reconstruction. measures used in the management of plinthic soils include mechanically breaking the hardpans and the use of organic and inorganic amendments to modify the structure and chemistry of the soils. Avoidance of practices that would predispose soils to erosion would also prevent plinthization. We call for the relinquishment of the term ＂[aterite＂ which is a generm term for all forms of iron oxide-enriched earthy materials as used for plinthite. Plinthic horizon should also be incorporated into the United States Department of Agriculture Soil taxonomy in view of its growing importance in soils.

关键词： agronomy pedogenesis petroplinthite soil taxonomy tropics

Some studies of the interaction between two two-level atoms and SU(1,1) quantum systems

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Chinese Physics B 2018年第10期27卷 116-122页

作者： t m El-Shahat m Kh Ismail faculty of Science Al-Azhar University. Assiut 71524 Egypt

Herein, we present an approach to look for the best phenomenon to measure quantum correlation. the system of two isolated qubits each interacting with a single-mode cavity was theoretically created to study the quantum correlation. Some of the phenomena, such as the quantum discord and concurrence, were generated through such a system. the influences of initial state purity, qubit motion, and detuning parameters were discussed for the phenomena. these parameters for a specific value show that the behavior of phenomena are analogous. It is interesting to mention that some values of detuning undergo a sudden death of phenomena, and the quantum discord still captures the qubits quantum correlation. We predict that the quantum discord may be a better measure of quantum correlation than concurrence.

关键词： an isolated atom with a cavity SU (1,1) quantum discord concurrence

Delay-dependent Robust Stabilization and H_∞ Control for Uncertain Stochastic t-S fuzzy Systems with Discrete Interval and Distributed time-varying Delays

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International Journal of Automation and computing 2013年第1期10卷 18-31页

作者： P.Balasubramaniam t.Senthilkumar Department of mathematics Gandhigram Rural University

In this paper, delay-dependent robust stabilization and H∞ control for uncertain stochastic takagi-Sugeno （t-S） fuzzy systems with discrete interval and distributed time-varying delays are discussed. the purpose of the robust stochastic stabilization problem is to design a memoryless state feedback controller such that the closed-loop system is mean-square asymptotically stable for all admissible uncertainties. In the robust H∞ control problem, in addition to the mean-square asymptotic stability requirement, a prescribed H∞ performance is required to be achieved. Sufficient conditions for the solvability of these problems are proposed in terms of a set of linear matrix inequalities （LmIs） and solving these LmIs, a desired controller can be obtained. finally, two numerical examples are given to illustrate the effectiveness and less conservativeness of our results over the existing ones.

关键词： Robust stability robust H∞ control stochastic fuzzy systems distributed delay linear matrix inequality (LmI)

Extraction of the defect density of states in microcrystalline silicon from experimental results and simulation studies

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Journal of Semiconductors 2015年第9期36卷 15-19页

作者： t.tibermacine A.merazga m.Ledra n.Ouhabab Laboratory of metallic and Semi-conducting materials University of Biskra Physics Department Faculty of ScienceTaif University

the constant photocurrent method in the ac-mode （ac-CPm） is used to determine the defect density of states （DOS） in hydrogenated microcrystalline silicon （μc-Si：H） prepared by very high frequency plasma-enhanced chemical vapor deposition （VHf-PECVD）. the absorption coefficient spectrum （ac-α （h v））, is measured under ac- CPm conditions at 60 Hz. the measured ac-α（hv） is converted by the CPm spectroscopy into a DOS distribution covering a portion in the lower energy range of occupied states. We have found that the density of valence band- tail states falls exponentially towards the gap with a typical band-tail width of 63 meV. Independently, computer simulations of the ac-CPm are developed using a DOS model that is consistent with the measured ac-α（hv） in the present work and a previously measured transient photocurrent （tPC） for the same material. the DOS distribution model suggested by the measurements in the lower and in the upper part of the energy-gap, as well as by the numerical modelling in the middle part of the energy-gap, coincide reasonably well with the real DOS distribution in hydrogenated microcrystalline silicon because the computed ac-α（h v） is found to agree satisfactorily with the measured ac-α （h v）.

关键词： constant photocurrent method optical absorption spectrum micro-crystalline silicon defect densityof states

A comprehensive review of significant researches on content based indexing and retrieval of visual information

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frontiers of Computer Science 2013年第5期7卷 782-799页

作者： R. PRIYA t. n. SHAnmUGAm Department of mathematics Anna University-Chennai Chennai 600 025 India

Developments in multimedia technologies have paved way for the storage of huge collections of video doc- uments on computer systems. It is essential to design tools for content-based access to the documents, so as to allow an efficient exploitation of these collections. Content based anal- ysis provides a flexible and powerful way to access video data when compared with the other traditional video analysis tech- niques. the area of content based video indexing and retrieval （CBVIR）, focusing on automating the indexing, retrieval and management of video, has attracted extensive research in the last decade. CBVIR is a lively area of research with endur- ing acknowledgments from several domains. Herein a vital assessment of contemporary researches associated with the content-based indexing and retrieval of visual information. In this paper, we present an extensive review of significant researches on CBV1R. Concise description of content based video analysis along with the techniques associated with the content based video indexing and retrieval is presented.

关键词： nultimedia information content based video retrieval (CBVR) content based video indexing and retrieval (CBVIR) shot segmentation object segmentation feature extraction indexing motion estimation querying key frame retrieval and indexing.