检索结果-南通市图书馆

Journal of Magnesium and Alloys 2024年第5期12卷 1815-1829页

作者： Eunji Song Mohsen Taheri Andani amit misra Department of Materials Science and Engineering University of MichiganAnn ArborMI 48109USA Department of Mechanical Engineering University of MichiganAnn ArborMI 48109USA Department of Mechanical Engineering Texas A&M UniversityCollege StationTX 77843USA

In situ tensile testing in a scanning electron microscope(SEM)in conjunction with high-resolution electron backscatter diffraction(HR-EBSD)under load was used to characterize the evolution of geometrically necessary dislocation(GND)densities at individual grain boundaries as a function of applied strain in a polycrystalline Mg-4Al *** increase in GND density was investigated at plastic strains of 0%,0.6%,2.2%,3.3% from the area including 76 grains and correlated with(i)geometric compatibility between slip systems across grain boundaries,and(ii)plastic *** develop expressions for the grain boundary GND density evolution as a function of plastic strain and plastic incompatibility,from which uniaxial tensile stress-strain response of polycrystalline Mg-4Al are computed and compared with experimental *** findings in this study contribute to understanding the mechanisms governing the strain hardening response of single-phase polycrystalline alloys and more reliable prediction of mechanical behaviors in diverse microstructures.

关键词： Mg-Al alloys Grain boundaries Geometrically necessary dislocations Strain gradient plasticity HR-EBSD

维普期刊数据库

A combined experimental and crystal plasticity study of grain size effects in magnesium alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2023年第12期11卷 4445-4467页

作者： Aaditya Lakshmanan Mohsen Taheri Andani Mohammadreza Yaghoobi John Allison amit misra Veera Sundararaghavan Department of Aerospace Engineering University of MichiganAnn ArborMI48105USA Department of Materials Science and Engineering University of MichiganAnn ArborMI48105USA Department of Mechanical Engineering University of MichiganAnn ArborMI48105USA

This work presents a method to incorporate the micro Hall-Petch equation into the crystal plasticity finite element(CPFE) framework accounting for the microstructural features to understand the coupling between grain size, texture, and loading direction in magnesium *** effect of grain size and texture is accounted for by modifying the slip resistances of individual basal and prismatic systems based on the micro Hall-Petch equation. The modification based on the micro Hall-Petch equation endows every slip system at each microstructural point with a slip system-level grain size and maximum compatibility factor, which are in turn used to modify the slip resistance. While the slip-system level grain size is a measure of the grain size, the maximum compatibility factor encodes the effect of the grain boundary on the slip system resistance modification and is computed based on the Luster-Morris factor. The model is calibrated using experimental stress-strain curves of Mg-4Al samples with three different grain sizes from which the Hall-Petch coefficients are extracted and compared with Hall-Petch coefficients predicted using original parameters from previous work. The predictability of the model is then evaluated for a Mg-4Al sample with different texture and three grain sizes subjected to loading in different directions. The calibrated parameters are then used for some parametric studies to investigate the variation of Hall-Petch slope for different degrees of simulated spread in basal texture,variation of Hall-Petch slope with loading direction relative to basal poles for a microstructure with strong basal texture, and variation of yield strength with change in grain morphology. The proposed approach to incorporate the micro Hall-Petch equation into the CPFE framework provides a foundation to quantitatively model more complicated scenarios of coupling between grain size, texture and loading direction in the plasticity of Mg alloys.

关键词： Hall-Petch Crystal plasticity Grain size Texture Magnesium alloys

维普期刊数据库

Dislocations interaction induced structural instability in intermetallic Al_(2)Cu

在线全文

学校读者我要写书评

暂无评论

npj Computational Materials 2017年第1期3卷 240-246页

作者： Qing Zhou Jian Wang amit misra Ping Huang Fei Wang Kewei Xu State key Laboratory for Mechanical Behavior of Material School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China Mechanical and Materials Engineering University of Nebraska-LincolnLincolnNE 68588USA Department of Materials Science and Engineering University of MichiganAnn ArborMI 48109USA State Key Laboratory for Strength and Vibration of Mechanical Structures School of AerospaceXi’an Jiaotong UniversityXi’an 710049People’s Republic of China

Intermetallic precipitates are widely used to tailor mechanical properties of structural alloys but are often destabilized during plastic *** atomistic simulations,we elucidate structural instability mechanisms of intermetallic precipitates associated with dislocation motion in a model system of Al_(2)*** of non-coplanar dislocation dipoles during plastic deformation results in anomalous reactions-the creation of vacancies accompanied with climb and collective glide of dislocation associated with the dislocation core change and atomic shuffle-accounting for structural instability in intermetallic Al_(2)*** process is profound with decreasing separation of non-coplanar dislocations and increasing temperature and is likely to be operative in other non-cubic intermetallic compounds as well.

关键词： intermetallic deformation structural

A novel approach towards molecular memory device in gate tunable structure of MoS_(2)-graphene

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1期14卷 177-184页

作者： Rahul Tripathi Abha misra Department of Instrumentation and Applied Physics Indian Institute of Sciencey BangaloreKarnataka 560012India

Molecular interaction in two-dimensional(2D)van der Waals(vdW)interfaces has drawn tremendous attention for extraordinary materials *** sensing characteristics of molecular interaction has been exploited extensively to reach the detection limit to a few parts-per-billion(ppb)of molecules and far less attention is given to the evolution of persistent current state due to the molecular *** study focuses on molecular memory operation of MoS_(2)-graphene heterostructure based field effect *** resistance state of the device due to the external perturbation of molecules is tuned to get a nearly relaxation free current state at much lower molecular concentration of 10 ppb tofacilitate non-volatile memory features for molecular memory *** ultrafast switching operation in milli-second order is achieved at room temperature for the fastest recovery obtained sofar in any molecular *** process is co-controlled both by molecular as well as external charge density.

关键词： MoS_(2) graphene field effect transistor molecular memory trap charges

Ileoscopy in patients with ileocolonic tuberculosis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2007年第11期13卷 1723-1727页

作者： SP misra Vatsala misra Manisha Dwivedi Department of Gastroenterology and Pathology Moti Lal Nehru Medical College University of Allahabad Allahabad 211 001 India

AIM: To study the role of retrograde terminal ileoscopy in patients suspected to have ileocolonic tuberculosis. METHODS: A retrospective analysis was performed for patients undergoing colonoscopy for suspected ileocolonic tuberculosis between January 2000 and June 2004, in whom retrograde ileoscopy had been performed. Only patients diagnosed with tuberculosis on the basis of histological findings of either a caseating granuloma or those having non-caseating granuloma or a collection of epithelioid cells at a minimum of one endoscopic lesion (either in the colon or the terminal ileum) on histology with good responses to conventional anti-tuberculous drugs were enrolled for the study. RESULTS: Fifty-three patients were included. The terminal ileum was involved in only 11 patients. Eight of these patients had involvement of the cecum too. Two patients had ileal lesions without cecal involvement; however, lesions were noted in the ascending colon. In one patient the whole colon was normal and only the terminal ileum showed nodularity and ulceration. Histological examination of the ileal biopsies obtained from the ileal lesions showed noncaseating granulomas in five, collection of epithelioid cells in four and nonspecific histology in two patients. Mucosal biopsies obtained from the lesion in the terminal ileum, in the patient in whom mucosal abnormality was observed to be confined to the ileum, showed noncaseating granulomas. In two other patients the ileal biopsies alone showed histological evidence of tuberculosis with biopsies from the colonic lesions showing non-specific inflammatory changes only. CONCLUSION: Retrograde ileoscopy should be performed in all patients undergoing colonoscopy for suspected ileocolonic tuberculosis. In some patients only the terminal ileum may be involved and histological examination may reveal evidence of tuberculosis only from the lesions in the terminal ileum. This approach would lead to additional lesions being picked up andincreasing

关键词： Tuberculosis Ileoscopy Colonoscopy

Surface plasmon oscillations in a semi-bounded semiconductor plasma

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Plasma Science and Technology 2018年第2期20卷 76-81页

作者： M SHAHMANSOURI A P misra Department of Physics Faculty of ScienceArak University Department of Mathematics Siksha BhavanaVisva-Bharati University

We study the dispersion properties of surface plasmon（SP） oscillations in a semi-bounded semiconductor plasma with the effects of the Coulomb exchange（CE） force associated with the spin polarization of electrons and holes as well as the effects of the Fermi degenerate pressure and the quantum Bohm *** from a quantum hydrodynamic model coupled to the Poisson equation,we derive the general dispersion relation for surface plasma *** results in this context are *** dispersion properties of the surface waves are analyzed in some particular cases of interest and the relative influence of the quantum forces on these waves are also studied for a nano-sized Ga As semiconductor *** is found that the CE effects significantly modify the behaviors of the SP *** present results are applicable to understand the propagation characteristics of surface waves in solid density plasmas.

关键词： surface plasmon oscillations semiconductor plasma semi-bounded plasma

维普期刊数据库

Ileoscopy in 39 hematochezia patients with normal colonoscopy

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2006年第19期12卷 3101-3104页

作者： SP misra M Dwivedi V misra Department of Gastroenterology and Pathology Moti Lal Nehru Medical College Allahabad 211001India

AIM： To assess the role of retrograde terminal ileoscopy in hematochezia patients with normal colonoscopy. METHODS： Between January 1997 and March 2005, 39 hematochezia patients （males 36, females 3, mean age 44.7 years） with a reported normal colonoscopy underwent a repeat colonoscopy. After reaching the cecum, attempt was made to localize the ileocecal valve and intubate the terminal ileum. Any abnormality in the mucosa of the terminal ileum was carefully recorded and biopsies were obtained from suspiciouslooking lesions. RESULTS： During the study period there were 39 patients admitted for hematochezia in whom colonoscopy till cecum did not reveal any abnormality. Fulllength colonoscopy till the cecum could be performed in all the patients. The terminal ileum could be intubated in 36 patients. No abnormality was noted in 31 patients. Ileal ulcers were noted in two patients. Noclularity along with ulceration of the ileal mucosa, a Dieulafoy＇s lesion, and an angiomatous malformation were noted in one patient each. Histological examination of the biopsies obtained from the ulcers revealed typical tuberculous lesion in the patient with nodularity and ulceration. One of the patients had typhoid ulcers and another had non-specific ulcers. CONCLUSION： Retrograde terminal ileoscopy gives limited but valuable information, in patients with hematochezia and should be attempted in all such patients.

关键词： Endoscopy Ileum Colon Diagnosis Tuberculosis Ulcer GI bleeding

Endoscopic management of a new entity-plastobezoar:A case report and review of literature

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2006年第41期12卷 6730-6733页

作者： SP misra Manisha Dwivedi Vatsala misra Department of Gastroenterology and Pathology Motilal Nehru Medical College Allahabad 211 001India

Foreign bodies and bezoars are commonly encountered in children. We describe a child aged 11 years who ingested large amounts of plastic material used for knitting chairs and charpoys. The conglomerate of plastic threads, entrapped food material and other debris, formed a huge mass occupying the whole stomach. Chronic irritation of the gastric antral mucosa led to ulceration and formation of hyperplastic polyps. We labeled this new entity as a “plastobezoar”. The entire bezoar could be removed endoscopically.

关键词： Bezoar Stomach Gastric Endoscopy Foreign body Gastric polyps Plastic

Hydrometeorological assessments and suspended sediment delivery from a central Himalayan glacier in the upper Ganga basin

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 Sediment Research 2018年第4期33卷 493-509页

作者： amit Kumar Akshaya Verma Anupam Anand Gokhale Rakesh Bhambri Anshuman misra Shipika Sundriyal Dwarika Prasad Dobhal Naval Kishore Centre for Glaciology Wadia Institute of Himalayan Geology Centre of Advanced Study in Geology Department of Geology Panjab University

Integrated hydrometeorological investigations are not frequently available at a regional scale over a longer time period, especially near the terminus of Indian Himalayan glaciers. An integrated approach to the collection of hydrological data has major advantages for understanding the runoff generation mechanisms at basin scale, particularly when coupled with meteorological observations. The current study involves time series analysis of hydrometeorological records collected near the terminus of the Chorabari Glacier, for four consecutive ablation seasons(June-Sept.) 2009-2012. The analysis shows that variation in rainfall was higher(c= 0.9) at the same elevation over proximal sites, while the intensity of extreme rainfall events was 121-160 mm/d. The diurnal temperature range(DTR) has a tendency to reduce over the ablation season because of the onset of the Indian Summer Monsoon(ISM) and then further increases during the ISM withdrawal indicating humid-temperate conditions. The peak discharge(Qpeak) was found to be higher during July and August. Snow and glacier melt contributed 76% of the total suspended sediment transport during peak ISM months(July and August) reflecting seasonal evolution of the hydrologic conduits. The results indicate that Karakoram and western Himalayan glaciers produce comparatively low sediment yield compared to central Himalayan glaciers. The hydrological variations are depicted through flow duration curves(FDC) for meltwater discharge and sediment load. The flow corresponding to Q, Q, and Q(where Qx is the discharge that is exceeded x percent of the time referred to as % dependability) are 4.2, 3.7, and 2.8 m~3/s; and the corresponding dependability for suspended sediment loads(SSLs) are 409.0, 266.0, and 157.2 t/d, respectively. The daily SSL and discharge(Q) from 2009 to 2012 were used to develop a sediment rating curve(SSL = 39.55 × Q. R~2 = 0.8).Multiple regressions are used to determine the impacts of meteorological parameters on gl

关键词： High elevation meteorology Suspended sediment transport Flow duration curves Multivariate regression Indian summer monsoon

Ileocecal masses in patients with amebic liver abscess:Etiology and management

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2006年第12期12卷 1933-1936页

作者： Sri Prakash misra Vatsala misra Marisha Dwivedi Department of Gastroenterology and Pathology Moti Lal Nehru Medical CollegeAllahabad 211001India

AIM. To assess the causes of ileocecal mass in patients with amebic liver abscess. METHODS： Patients with amebic liver abscess and ileocecal mass were carefully examined and investigated by contrast-enhanced CT scan followed by colonoscopy and histological examination of biopsy materials from lesions during colonoscopy. RESULTS： Ileocecal masses were found in seventeen patients with amebic liver abscess. The cause of the mass was ameboma in 14 patients, cecal tuberculosis in 2 patients and adenocarcinoma of the cecum in 1 patient. Colonic ulcers were noted in five of the six （83%） patients with active diarrhea at presentation. The ileocecal mass in all these patients was ameboma. Ulcers were seen in only one of the 11 （9%） patients without diarrhea. The difference was statistically significant from the group with diarrhea （P〈 0.005）. CONCLUSION： Ileocecal mass is not an uncommon finding in patients with amebic liver abscess. Although, the ileocecal mass is due to ameboma formation in most cases, it should not be assumed that this is the case in all patients. Colonoscopy and histological examination of the target biopsies are mandatory to avoid missing a more sinister lesion.

关键词： Amebiasis Ameboma Colon Colonoscopy Diagnosis