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Relationship between the microstructure and properties of thermomechanically processed Fe-17Mn and Fe-17Mn-3Al steels

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International Journal of Minerals,Metallurgy and Materials 2019年第1期26卷 64-75页

作者： Renuprava Dalai Siddhartha das Karabi das Department of Metallurgical and Materials Engineering Indian Institute of Technology

Two austenitic Mn steels(Fe-17 Mn and Fe-17 Mn-3 Al(wt%, so as the follows)) were subjected to thermomechanical processing(TMP) consisting of forging followed by solutionization and hot rolling. The rolled samples were annealed at 650 and 800°c to relieve the internal stress and to induce recrystallization. The application of TMP and heat treatment to the Fe-17 Mn/Fe-17 Mn-3 Al steels refined the austenite grain size from 169 μm in the as-solutionized state to 9–13 μm, resulting in a substantial increase in hardness from HV 213 to HV 410 for the Fe-17 Mn steel and from HV 210 to HV 387 for the Fe-17 Mn-3 Al steel. The elastic modulus values, as evaluated by the nanoindentation technique, increased from(175 ± 11) to(220 ± 12) gPa and from(163 ± 15) to(205 ± 13) gPa for the Fe-17 Mn and Fe-17 Mn-3 Al steels, respectively. The impact energy of the thermomechanically processed austenitic Mn steels was lower than that of the steels in their as-solutionized state. The addition of Al to the Fe-17 Mn steel decreased the hardness and elastic modulus but increased the impact energy.

关键词： austenitic manganese steel(AMS) thermomechanical processing(TMP) microstructure property hardness elastic modulus

Effect of size on momentum distribution of electrons around vacancies in NiO nanoparticles

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chinese Physics B 2015年第4期24卷 296-299页

作者： Anjan das Atis chandra Mandal P.M.g.Nambissan Department of Physics A.P.C.Roy Government College Department of Physics University of Burdwan Applied Nuclear Physics Division Saha Institute of Nuclear Physics

Very small nickel oxide nanoparticles were prepared by a sol-gel procedure using nickel nitrate hexahydrate and ammonium hydroxide as precursors. The particles are in the range of 5 nm-11 rim. The x-ray diffraction （XRD） crystallography and high resolution transmission electron microscopy （HRTEM） were employed to characterize the samples. They were found to be polycrystalline in nature and fcc （Nacl-type） in structure, with the lattice parameter varying with annealing temperature. HRTEM pictures show that the as-prepared samples are hexagonal in shape. Positron annihilation spectroscopy was used to investigate the Doppler-broadened spectra of the samples. The S and W parameters revealed that the chemical surroundings and momentum distribution of the vacancy clusters vary with crystallite size.

关键词： nanoparticles semiconductor defect cluster positron annihilation sol-gel

Potential therapeutic roles of retinoids for prevention of neuroinflammation and neurodegeneration in Alzheimer’s disease

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Neural Regeneration Research 2019年第11期14卷 1880-1892页

作者： Bhaskar c. das Somsankar dasgupta Swapan K. Ray Department of Medicine Icahn School of Medicine at Mount SinaiNew YorkNYUSA Department of Neuroscience and Regenerative Medicine Institute of Molecular Medicine and GeneticsAugusta UniversityAugustaGAUSA Department of Pathology Microbiologyand ImmunologyUniversity of South Carolina School of MedicineColumbiaSCUSA

All retinoids, which can be natural and synthetic, are chemically related to vitamin A. Both natural and synthetic retinoids use specific nuclear receptors such as retinoic acid receptors and retinoid X receptors to activate specific signaling pathways in the cells. Retinoic acid signaling is extremely important in the central nervous system. Impairment of retinoic acid signaling pathways causes severe pathological processes in the central nervous system, especially in the adult brain. Retinoids have major roles in neural patterning, differentiation, axon outgrowth in normal development, and function of the brain. Impaired retinoic acid signaling results in neuroinflammation, oxidative stress, mitochondrial malfunction, and neurodegeneration leading to progressive Alzheimer’s disease, which is pathologically characterized by extra-neuronal accumulation of amyloid plaques(aggregated amyloid-beta) and intra-neurofibrillary tangles(hyperphosphorylated tau protein) in the temporal lobe of the brain. Alzheimer’s disease is the most common cause of dementia and loss of memory in old adults. Inactive cholinergic neurotransmission is responsible for cognitive deficits in Alzheimer’s disease patients. Deficiency or deprivation of retinoic acid in mice is associated with loss of spatial learning and memory. Retinoids inhibit expression of chemokines and neuroinflammatory cytokines in microglia and astrocytes, which are activated in Alzheimer’s disease. Stimulation of retinoic acid receptors and retinoid X receptors slows down accumulation of amyloids, reduces neurodegeneration, and thereby prevents pathogenesis of Alzheimer’s disease in mice. In this review, we described chemistry and biochemistry of some natural and synthetic retinoids and potentials of retinoids for prevention of neuroinflammation and neurodegeneration in Alzheimer’s disease.

关键词： Alzheimer's disease amyloid plaques neurofibrillary tangles neuroinflammation neurodegeneration retinoids

Electrochemically functionalized graphene as an anti-corrosion reinforcement in cu matrix composite thin films

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International Journal of Minerals,Metallurgy and Materials 2021年第9期28卷 1525-1533页

作者： Akhya kumar Behera Amlan das Sanjeev das Archana Mallik Electrometallurgy and corrosion Laboratory(Research) Department of Metallurgical and Materials EngineeringNational Institute of TechnologyRourkela 769008OdishaIndia Advanced Metal casting Laboratory Department of Metallurgical and Materials EngineeringNational Institute of TechnologyRaipur 492010ChhatisgarhIndia

cu-graphene(gr)composite thin films were prepared by electrodeposition route using in-house synthesized gr *** gr sheets were synthesized by the electrochemical exfoliation route using 1 M HclO4 acid as *** gr sheets were confirmed by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field-emission scanning electron microscopy(FESEM),and transmission electron microscopy(TEM).The(002)plane of gr sheets was observed at 2θof 25.66°.The(002)plane confirmed the crystal structure of car-bon *** stretching vibration of c=c bond at a wavelength of 1577 cm^(−1) and other functional groups of carboxyl and epoxide groups were observed from *** confirmed the transparent structure of gr *** prepared gr sheets were used as reinforcement at con-centrations of 0.1 and 0.3 g/L with a copper matrix to synthesize the cu-gr *** prepared composite thin films were characterized by XRD,SEM,and energy-dispersion spectrometry(EDS)for morphological and analytical *** presence of gr sheets in cu-gr com-posite was confirmed by EDS *** prepared cu-gr nanocomposite thin film showed higher corrosion resistance compared with pure copper thin films in 3.5wt%Nacl,as confirmed by Tafel *** impedance spectroscopy complimented the above results and showed that 0.3 g/L composite film achieved the highest film resistance.

关键词： graphene nanocomposite electrodeposition copper

Synthesis and characterization of lanthanide-doped sodium holmium fluoride nanoparticles for potential application in photothermal therapy

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Frontiers of Materials Science 2019年第4期13卷 389-398页

作者： Kaushik das c.A.KUMAR Leonardo MIRANDOLA Maurizio cHIRIVAJNTERNATI Jharna cHAUDHURI Department of Mechanical Engineering Texas Tech UniversityLubbockTX 79409USA Department of Physics and Astronomy University of Texas at San AntonioSan AntonioTX 78249USA Department of Atomic and Molecular Physics Manipal UniversityManipal 576104KarnatakaIndia Department of Natural and Physical Sciences Northwest Vista College3535 N Ellison DrSan AntonioTX 78251USA Kiromic BioPharma 7707 Fannin St.Suite 140Houston.TX 77054USA Department of gastroenterology Hepatology and NutritionUniversity of Texas MD Anderson Cancer CenterHoustonTX 77030USA Department of Mechanical and Materials Engineering PO Box 751Portland State UniversityPortlandOR 97207-0751USA

Upconversion nanoparticles(Uc NPs)in combination with plasmonic materials have great potential for cancer photothermal ***,sodium holmium fluoride(NaHoF4)is being investigated for luminescence and magnetic resonance imaging(MRI)contrast ***,we present successful synthesis of excellent quality doped NaHoF4 NPs for possible Uc luminescence application and coated for possible photothermal therapy *** NaHoF4 nanocrystals were doped with Yb/Er and coated with gold,gold/silica,silver and polypyrrole(PPy).XRD,XPS and TEM were used to determine structure and morphology of the *** Uc photoluminescence(PL)emission spectra were obtained from the NPs when excited by near-infrared(NIR)light at 980 *** viability and toxicity of the NPs were characterized using pancreatic and ovarian cancer cells with results showing that gold/silica coating produced least toxicity followed by gold coating.

关键词： photothermal therapy upconversion photoluminescence nanoparticle sodium holmium fluoride

Diversity and structural composition of species in dipterocarp forests:a study from Fasiakhali Wildlife Sanctuary, Bangladesh

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Journal of Forestry Research 2018年第5期29卷 1241-1249页

作者： S.c.das M.S.Alam M.A.Hossain Institute of Forestry and Environmental Sciences University of Chittagong

Fasiakhali Wildlife Sanctuary is a protected area composed of tropical remnant rainforest that harbor substantial number of large,old garjan（Dipterocarpus spp.）*** present study assessed composition,structure and diversity of the species in this protected area.A total of 32 trees species were recorded with DBH ≥ 11 cm belonging to 24 genera and 19 *** forest is low in plant diversity as represented by Shannon–Wiener diversity and Simpson Dominance *** turbinatus was the most dominant species with maximum relative density,frequency,dominance,and importance value *** firmum and Tectona grandis followed in terms of *** structural composition indicated higher number of individuals in the medium growth classes（41 to 〈 511 cm DBH and 16–20 m height ranges）,whereas *** was the only species that dominated most of the growth *** stem density in lower growth classes indicated meager recruitment of regeneration which may be due to lower annual precipitation,increased grazing and *** study will help to understand the patterns of tree species composition and diversity in the remnant dipterocarp forests of *** will also contribute to identifying threatened plants to undertake *** based conservation and sustainable management of the Fasiakhali Wildlife Sanctuary.

关键词： Species diversity Structural composition Protected area Importance value index cluster analysis

Left-turn phasing selection considering vehicle to vehicle and vehicle to pedestrian conflicts

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第1期10卷 58-69页

作者： Kakan c.Dey Md Tawhidur Rahman Subasish das Amrit Manova Williams Wadsworth Department of civil and Environmental Engineering West Virginia UniversityMorgantownWV 26506USA AEcOM Technical Services Inc.PhoenixAZ 85020USA Ingram School of Engineering Texas State UniversitySan MarcosTX 78666USA Davenport Engineering CharlotteNC 28273USA

Left-turning vehicle movement at signalized intersections with permissive left-turn phases creates safety concerns due to the higher chance of conflict with opposing-through vehicles and *** this research,a simulation-based study was conducted to evaluate pedestrians’impact on traffic conflicts between left-turning vehicles and opposing-through vehicles(V-V conflicts)as well as traffic conflicts between left-turning vehicles and pedestrians(V-P conflicts)in the permissive left-turn phasing *** with different opposing-through volumes,left-turn volumes,number of opposing-through lanes,and pedestrian volumes were modeled in VISSIM,a traffic *** surrogate safety assessment model(SSAM)was used to estimate the number of V-V and VP *** effect of pedestrian presence on V-V and V-P conflicts was evaluated using simulation scenarios with and without pedestrian *** results revealed that pedestrian presence increased both V-V and V-P *** pedestrian presence increased the total number of traffic conflicts,permissive left-turn phasing processed fewer left-turn vehicles to maintain the same level of intersection safety with pedestrian presence compared to the no-pedestrian *** current left-turn phasing decision guidelines do not consider the impacts of pedestrian presence,this research quantified pedestrian-influenced and pedestrian-involved left-turn traffic conflicts to determine appropriate left-turn signal phasing decisions to ensure safe and efficient crossing of pedestrians and vehicles at signalized *** simulation-based study’s findings can be beneficial in the decision making of left-turn phasing selection as the before-after intersection safety performance analysis by collecting field data often resources intensive.

关键词： V-V conflicts V-P conflicts Left-turn phasing Pedestrian Warrants

Mechanism of cd(II) adsorption by macrofungus Pleurotus platypus

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Journal of Environmental Sciences 2011年第2期23卷 288-293页

作者： R.Vimala Nilanjana das School of Biosciences and Technology VIT University

The mechanism of cd（Ⅱ） uptake by the dead biomass of macrofungus Pleurotus platypus was investigated using different chemical and instrumental techniques. Sequential removal of cell wall components of the biosorbent revealed that structural polysaccharides play a predominant role in the biosorption of cd（Ⅱ）. The adsorption kinetics fitted well with the pseudo second-order model suggested that the adsorption of cd（Ⅱ） on P. platypus involved a chemisorption process. Transmission electron microscopy of the cadmium exposed biomass confirmed the deposition of the metal mainly in the metal loaded biosorbent confirmed the participation of-OH, - the cell wall. Fourier transform infrared spectroscopic analysis of NH and c-O-c groups in the uptake of cd（Ⅱ）. Energy dispersive X-ray analysis of the biosorbent before and after metal uptake revealed that the main mechanism of adsorption was ion-exchange. The effectiveness of cacl2 in the desorption of cadmium perhaps suggested the exchange of ca^2＋ with cd（Ⅱ）.

关键词： biosorption mechanism ion-exchange Pleurotus platypus macrofungus cadmium

Hydromagnetic flow between two porous disks rotating about non-coincident axes

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Acta Mechanica Sinica 2008年第5期24卷 489-496页

作者： M.guria B.K.das R.N.Jana c.Erdem Imrak Department of Applied Mathematics Vidyasagar UniversityMidnapore 721 102West BengalIndia Department of Mechanical Engineering Istanbul Technical UniversityGumussuyuIstanbul 34439Turkey

Hydromagnetic flow between two porous disks rotating with same angular velocity Ω about two noncoincident axes has been studied in the presence of a uniform transverse magnetic field. An exact solution of the governing equations has been obtained in a closed form. It is found that the primary velocity f/Ωl increases and the secondary velocity g/Ωl decreases with increase in either Reynolds number Re or the Hartman number M. It is also found that the torque at the disk η= 0 increases with increase in either M^2 or K^2. On the other hand there is no torque at the disk η= 1 for large M^2 and K^2. The heat transfer characteristic has also been studied on taking viscous and Joule dissipation into account. It is seen that the temperature increases with increase in either M^2 or K^2. It is found that the rate of heat transfer at the disk η= 0 increases with increase in either M or K. On the other hand the rate of heat transfer at the disk η= 1 increases with increase in K but decreases with increase in M.

关键词： Non-coincident Viscous fluid Torque ,Hydromagnetic