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Additive friction stir deposition of AZ31B magnesium alloy

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Journal of Magnesium and Alloys 2022年第9期10卷 2404-2420页

作者： Sameehan S.Joshi Shreyash M.Patil Sangram mazumder Shashank Sharma Daniel A.Riley Shelden Dowden Rajarshi Banerjee Narendra B.Dahotre Department of Materials Science and Engineering University of North Texas3940 N Elm StDentonTX 76207USA Center for Agile and Adaptive Additive Manufacturing University of North Texas3940 N Elm StDentonTX 76207USA

The current work explored additive friction stir deposition of AZ31B magnesium alloy with the aid of MELD?***31B magnesium bar stock was fed through a hollow friction stir tool rotating at constant velocity of 400 rpm and translating at linear velocity varied from 4.2 to 6.3 mm/s.A single wall consisting of five layers with each layer of 140×40×1 mm^(3)dimensions was deposited under each processing ***,phase,and crystallographic texture evolutions as a function of additive friction stir deposition parameters were studied with the aid of scanning electron microscopy including electron back scatter diffraction and X-ray *** feed material and additively produced samples consisted of theα-Mg *** additively produced samples exhibited a refined grain structure compared to the feed *** feed material appeared to have a weak basal texture,while the additively produced samples experienced a strengthening of this basal *** additively produced samples showed a marginally higher hardness compared to the feed *** current work provided a pathway for solid state additive manufacturing of Mg suitable for structural applications such as automotive components and consumable biomedical implants.

关键词： Additive friction stir deposition Magnesium alloys Additive manufacturing Thermomechanical processing Materials processing Solid state additive manufacturing

Fabrication and characterization of a GaN/(4H)SiC vertical pn power diode using direct and interfaced epitaxial-growth approaches

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Journal of Semiconductors 2013年第4期34卷 20-23页

作者： Bose Srikanta mazumder S K Laboratory for Energy and Switching-Electronics Systems Department of Electrical and Computer EngineeringUniversity of Illinois at ChicagoChicagoIL:60607USA

We report the fabrication and characterization of a vertical pn power diode which is realized using two separate epitaxial-growth mechanisms：（a） p-GaN over p-（4H）SiC, and （b） p-GaN over n-（4H）SiC with A1N as the interface layer. In all of the cases, n＋-doped （4H）SiC serves as the cathode substrate. Pd（200 A）/Au（10000 A） is used for the anode contact while Ni（1000A） is used for the bottom cathode contact. The measured forward drop of the pn diode with A1N as the interface material is found to be around 5.1 V; whereas, it is 3 V for the other sample structure. The measured reverse-blocking voltage is found to be greater than 200 V.

关键词： GaN (4H)SiC vertical pn power diode power electronics

Preparation,crystallization,microstructure and dielectric properties of lead bismuth titanate borosilicate glass ceramics

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Journal of Advanced Ceramics 2014年第3期3卷 194-206页

作者： Chandkiram RGAUTAM Abhishek MADHESHIYA Ranabrata mazumder Advanced Glass and Glass Ceramic Research Laboratory Department of PhysicsUniversity of LucknowLucknow 226007India Department of Ceramic Engineering National Institute of TechnologyRouerkela 769008India

Various bulk and transparent glasses were prepared by rapid melt quenching technique in the glass system 55[(Pb_(x)Bi_(1-x))TiO_(3)]-44[2Si_(O)2B_(2)O_(3)]-La2O3(x=0-0.7).The X-ray diffraction(XRD)studies of the glass samples confirmed the amorphous *** differential thermal analyses(DTA)were carried out from room temperature to 900℃with a heating rate of 10℃/*** DTA patterns of the samples showed one or more exothermic sharp peaks shifting towards lower temperature side with increasing concentration of bismuth oxide(BiO).On the basis of DTA results,the solid solution of bismuth titanum oxide(Bi_(2)Ti_(2)O_(7))/lead bismuth titanium oxide(Pb3Bi4Ti6O21)was precipitated in borosilicate glassy matrix as a major *** glasses were subjected to 4 h and 8 h heat treatment schedules to convert into glass *** analysis of these glass ceramic samples showed that the major crystalline phase of the entire glass ceramic samples with 0≤x≤0.5 is found to have cubic crystal structure,while it is tetragonal for glass ceramic sample with x=*** scanning electron microscopy(SEM)micrographs indicated the uniform distribution of Bi_(2)Ti_(2)O_(7)and Pb3Bi4Ti6O21 crystallites in the glassy matrix.

关键词： lead bismuth titanate differential thermal analysis(DTA) crystallization scanning electron microscopy(SEM) dielectric behavior

Thermal conductivity of dense hcp iron:Direct measurements using laser heated diamond anvil cell

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Geoscience Frontiers 2020年第5期11卷 1755-1761页

作者： Pinku Saha Aritra mazumder Goutam Dev Mukherjee National Centre for High Pressure Studies Department of Physical SciencesIndian Institute of Science Education and Research KolkataMohanpur CampusMohanpur741246NadiaWest BengalIndia

Thermal conductivity(k)of iron is measured up to about 134 *** measurements are carried out using the single sided laser heated diamond anvil cell,where the power absorbed by a Fe metal foil at hotspot is calculated using a novel thermodynamical *** conductivity of fee(γ)-Fe increases up to a pressure of about46 *** find thermal conductivity values in the range of 70-80 Wm-1K-1(with an uncertainty of 40%),almost constant with pressure,in the hcp(e)phase of *** attribute the pressure independent k above 46 GPa to the strong electronic correlation effects driven by the electronic topological transition(ETT).We predict a value of thermal conductivity ofε-Fe of about 40±16 Wm-1K-1 at the outer core of Earth.

关键词： Laser heated diamond anvil cell Thermal conductivity High pressure effects Geodynamo

Biological, chemical and pharmacological aspects of Madhuca longifolia

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Asian Pacific Journal of Tropical Medicine 2018年第1期11卷 9-14页

作者： Dhruv Jha Papiya Mitra mazumder Birla Institute of Technology

Madhuca longifolia(M. longifolia) is also known as Mahua belonging to the family sapoteace family. M. longifolia is used in traditional and folklore system of medicine widely across India, Nepal, and Sri Lanka for its various pharmacological properties as in snake bites and in diabetes. Phytochemicals studies documented the different bioactive constituents, namely,glycosides, flavonoids, terpenes and saponins. The pharmacological studies proved that it possess wide range of biological activities such as antiulcer, antiinflammatory, antioxidant and antidiabetic activities. The toxicity studies reveal its non-toxic effect even at larger *** M. longifolia can be considered as a therapeutic agent for specific diseases. Scientific investigation on various isolated bioactive components and its efficacy on diseases proved the future usefulness of different species of Madhuca. This review summarizes the phytochemical,pharmacological, medicinal and non-medicinal uses of M. longifolia. Further exploration on *** for its therapeutic potential is however required for depth traditional knowledge.

关键词： Madhuca longifolia Phytochemistry Phatmacology Medicinal and non-medical uses

Immunomodulatory and anticancer activity of Bombax ceiba Linn leaf extract

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Asian Pacific Journal of Tropical Biomedicine 2020年第9期10卷 426-432页

作者： Neelima Sharma Sneha Kispotta Papiya Mitra mazumder Department of Pharmaceutical Sciences&Technology Birla Institute of TechnologyMesraRanchiIndia

Objective:To evaluate the immunomodulatory and anticancer activity of the methanolic extract of Bombax ceiba leaves in vitro and in ***:The antioxidant property of methanolic extract of Bombax ceiba leaves was determined by measuring hydrogen peroxide scavenging and DPPH scavenging *** effect on cellular immunity in vivo was determined by measuring neutrophil adhesion,carbon clearance,sheep red blood cell induced DTH response and cyclophosphamide-induced *** vitro anticancer activity was evaluated on human leukaemia cell line(HL-60)by MTT assay,caspase-3 activity,and cell cycle ***:The methanolic extract of Bombax ceiba leaves showed antioxidant activity and significantly increased neutrophil adhesion,carbon clearance from blood,DTH response and cyclophosphamideinduced *** MTT assay showed a significant increase in the death of HL-60 cell line.A rise in caspase-3 activity and sub-G1 population in the presence of methanolic extract of Bombax ceiba leaves was ***:The methanolic extract of leaves of Bombax ceiba L possesses anticancer activity,immunomodulatory activity,and antioxidant properties,proving its therapeutic usefulness in the treatment of immuno-compromised diseases and cancers.

关键词： Anticancer Antioxidative Bombax ceiba Immunomodulatory

Bed roughness and grain sorting-an experimental study over fine to medium sand beds

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International Journal of Sediment Research 2017年第3期32卷 384-400页

作者： Barendra Purkait Dipanjan Das Majumdar Rajat mazumder Geological Studies Unit Indian Statistical Institute Department of Geology University of Calcutta Department of Remote Sensing& GIS Vidyasagar University School of Biology Earth and Environmental Sciences University of New South Wales Dept. of Applied Geology Faculty of Engineering and Science Curtin University malaysia

The relation between grain-size distribution of the bed and in suspension was critically examined under a uniform flow velocity of 50 cm/s over two beds: one of mainly fine sands and the other of medium sands. Two sections-one 2.85 m downstream and the other 6.35 m downstream in the experimental channel-were selected for sampling to study the grain-sorting pattern in the vertical direction along the direction of transport. The shape and type of the grain-size distribution pattern were critically studied with height above the bed. The change in the distribution pattern has been attributed to the change of local bed roughness causing scouring against the protruded relatively coarse grains on the bed. Such trends are important to predict the nature of river bed topography. The sand of Bed-1 initially exhibits a log-skew-Laplace distribution at different heights of suspension. The distribution pattern, however,changes but this changing pattern is not consistent along the upstream side. For Bed-2, which initially exhibits a log-normal distribution, the same pattern persists from the height of suspension at 5 cm up to20 cm. Such consistency in log-normality is also observed at the downstream points of measurement. It is generally expected that the mean grain-size would reduce with increases of suspension height but the results of the experiments, in some occasions, differ significantly from the gradual fining upward *** result has been attributed to local changes of bed roughness arising from the protruded relatively coarse grains causing eddies, scouring, and turbulent phenomena which moves coarse particles higher in suspension adding a coarse tail to the distribution increasing the mean grain-size.

关键词： Flume experiments Suspension height Uniform flow velocity Bed roughness Grain-size distribution Bed scouring Turbulent flow

Contribution of β-phenethylamine, a component of chocolate and wine, to dopaminergic neurodegeneration: implications for the pathogenesis of Parkinson's disease

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Neuroscience Bulletin 2013年第5期29卷 655-660页

作者： Anupom Borah Rajib Paul Muhammed Khairujjaman mazumder Nivedita Bhattacharjee Department of Life Science and Bioinformatics Assam University

While the cause of dopaminergic neuronal cell death in Parkinson＇s disease（PD）is not yet understood,many endogenous molecules have been implicated in its pathogenesis.β-phenethylamine（β-PEA）,a component of various food items including chocolate and wine,is an endogenous molecule produced from phenylalanine in the *** has been reported recently that long-term administration ofβ-PEA in rodents causes neurochemical and behavioral alterations similar to that produced by parkinsonian *** toxicity ofβ-PEA has been linked to the production of hydroxyl radical（.OH）and the generation of oxidative stress in dopaminergic areas of the brain,and this may be mediated by inhibition of mitochondrial *** significant observation is that administration ofβ-PEA to rodents reduces striatal dopamine content and induces movement disorders similar to those of parkinsonian ***,no reports are available on the extent of dopaminergic neuronal cell death after administration ofβ-*** on the literature,we set out to establishβ-PEA as an endogenous molecule that potentially contributes to the progressive development of *** sequence of molecular events that could be responsible for dopaminergic neuronal cell death in PD by consumption ofβ-PEA-containing foods is proposed ***,long-term over-consumption of food items containingβ-PEA could be a neurological risk factor having significant pathological consequences.

关键词： oxidative stress hydroxyl radical mitochondrial complex-I α-synuclein Lewy body ubiquitinproteasome system

Contributions of burst-sweep cycles to Reynolds shear stress over fluvial obstacle marks generated in a laboratory flume

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International Journal of Sediment Research 2012年第3期27卷 378-387页

作者： H.MAITY B.S.mazumder Fluvial Mechanics Laboratory Physics and Applied Mathematics UnitIndian Statistical Institute

This paper investigates the phenomena of turbulent bursting events,and to make a comparative study among the events in the scour geometry developed by short circular cylinders of fixed length with different diameters placed on the sand bed transverse to the *** distributions of turbulent kinetic energy(TKE),turbulent diffusion in both longitudinal and vertical directions at different locations of scour marks,and the contributions of burst-sweep cycles to the Reynolds shear stress are presented.

关键词： Scour marks TKE Turbulent diffusion Reynolds stress Bursting events