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Geochemical and petrological studies of high sulfur coal and overburden from Mak.m coalfield (Northeast India) towards understanding and mitigation of acid mine drainage

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International Journal of Coal Science & Technology 2024年第1期11卷 133-147页

作者： Angana Mahanta Debashis Sarmah Nilotpol Bhuyan Monik.nk.na Saik.a Sarat Phuk.n k.S.V.Subramanyam ajit Singh Prasenjit Saik.a Binoy k.Saik.a Coal and Energy Division CSIR-North East Institute of Science and TechnologyJorhatAssam785006India Academy of Scientific&Innovative Research(AcSIR) Ghaziabad201002India Department of Geological Sciences Gauhati UniversityGuwahatiAssam781014India Geochemistry Division CSIR-National Geophysical Research InstituteUppal RoadHyderabad500007India

Opencast coal mining produces trash of soil and rock.containing various minerals,that are usually dumped nearby the abandoned sites which causes severe environmental concern including the production of acid mine drainage(AMD)through oxidation pyrite *** current study entailed assessing the potential production of AMD from an opencast coal mining region in Northeast part of *** order to have a comprehensive overview of the AMD problem in Mak.m coalfield,the physico-chemical,geochemical,and petrological characteristics of the coal and overburden(OB)samples collected from the Mak.m coalfield(Northeast India)were thoroughly *** maceral compositions reveal that coal features all three groups of macerals(liptinite,vitrinite,and inertinite),with a high concentration of liptinite indicating the coal of perhydrous,thereby rendering it more ***(FeS_(2))oxidation k.netics were studied by conducting the aqueous leaching experiments of coal and(OB)samples to interpret the chemical weathering under controlled laboratory conditions of various temperature and time periods,and to replicate the actual mine site *** coupled plasma-optical emission spectroscopy(ICP-OES)was operated to detect the disposal of some precarious elements from coal and OB samples to the leachates during our controlled leaching *** Rare earth element(REE)enrichment in the samples shows the anthropogenic incorporation of the REE in the coal and *** experiments reveal the change in conductivity,acid producing tendency,total dissolved solid(TDS),total Iron(Fe)and dissolved Sulfate(SO_(4)^(2−))ions on progress of the leaching ***,the discharge of FeS_(2) via atmospheric oxidation in laboratory condition undergoes a significant growth with the rise of temperature of the reaction systems in the environment and follows pseudo first order k.netics.A bio-remediative strategies is also reported in this paper to mitigate AMD water by

关键词： Opencast mining Pyrite oxidation Coal geochemistry Coal petrology Rare earth elements AMD remediation

Cardiovascular risk.factors among older persons with cognitive frailty in middle income country

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World Journal of Clinical Cases 2024年第17期12卷 3076-3085页

作者： Azianah Mohamad Ibrahim Devinder k.ur ajit Singh Arimi Fitri Mat Ludin Noor Ibrahim Mohamed Sak.an Nurul Fatin Malek.Rivan Suzana Shahar Centre for Healthy Ageing and Wellness Faculty of Health SciencesUniversiti Kebangsaan MalaysiaWilayah Persekutuan Kuala Lumpur 50300Malaysia Basic Medical Sciences University of CyberjayaSelangor Darul EhsanMalaysia 63000Malaysia

BACk.ROUND Cognitive frailty,characterized by the coexistence of cognitive impairment and physical frailty,represents a multifaceted challenge in the aging *** role of cardiovascular risk.factors in this complex interplay is not yet fully *** To investigate the relationships between cardiovascular risk.factors and older persons with cognitive frailty by pooling data from two cohorts of studies in *** A comprehensive approach was employed,with a total of 512 communitydwelling older persons aged 60 years and above,involving two cohorts of older persons from previous *** related to cardiovascular risk.,namely sociodemographic factors,and cardiovascular risk.factors,including hypertension,diabetes,hypercholesterolemia,anthropometric characteristics and biochemical profiles,were pooled for *** frailty was defined based on the Clinical Dementia Rating scale and Fried frailty *** risk.was determined using Framingham risk.*** analyses were conducted using SPSS version *** Of the study participants,46.3%exhibited cognitive *** risk.factors including hypertension(OR:1.60;95%CI:1.12-2.30),low fat-free mass(OR:0.96;95%CI:0.94-0.98),high percentage body fat(OR:1.04;95%CI:1.02-1.06),high waist circumference(OR:1.02;95%CI:1.01-1.04),high fasting blood glucose(OR:1.64;95%CI:1.11-2.43),high Framingham risk.score(OR:1.65;95%CI:1.17-2.31),together with sociodemographic factors,i.e.,being single(OR 3.38;95%CI:2.26-5.05)and low household income(OR 2.18;95%CI:1.44-3.30)were found to be associated with cognitive *** Cardiovascular-risk.specific risk.factors and sociodemographic factors were associated with risk.of cognitive frailty,a prodromal stage of *** identification and management of cardiovascular risk.factors,particularly among specific group of the population might mitigate the risk.of cognitive frailty,hence preventing dementia.

关键词： Cognitive frailty Older persons Cardiovascular risk.factors Frailty Mild cognitive impairment

Corrosion Study of Base Material and Welds of a Ni-Cr-Mo-W Alloy

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Acta Metallurgica Sinica(English Letters) 2017年第4期30卷 326-332页

作者： ajit Mishra Haynes International Inc. 1020 West Park AvenueKokomo IN 46904 USA

Alloys containing chromium （Cr） and molybdenum （Mo）, as the major alloying elements, are widely used in various industries where the material experiences corrosive environments. Chromium （Cr）, when added in an optimum amount, forms a Cr203 passive film which protects the underlying metal in aggressive solutions. Molybdenum （Mo） forms its oxides in the low pH solutions, thus, enhances the uniform corrosion resistance of an alloy in reducing acids and assists in inhibition to localized corrosion. Minor alloying elements, lik. tungsten （W） and copper （Cu）, also improve the overall corrosion resistance of an alloy in specific solutions. In the present study, corrosion resistance behavior of commercial iron- based alloys （316L SS, 254 SMO and 20Cb3） and nick.l-based alloys （Mone1400, Alloy 625 and C-276） was studied in the acidic solutions. While the corrosion behavior of wrought alloys has been widely studied, there is little to no information on the corrosion performance of their welds, typically being the weak.regions for corrosion initiation and propagation. Therefore, an attempt was undertak.n to investigate the uniform and localized corrosion performance of base metal, simulated heat-affected zone and all-weld-metal samples of a Ni-Cr-Mo-W alloy, C-276. The study was conducted in aggressive acidic solutions. Various corrosion and surface analytical techniques were utilized to analyze the results.

关键词： Iron-chromium-molybdenum Nick.l-chromium-molybdenum-tungsten All-weld-metal Heat-affected-zone Acids Acidified ferric chloride Potentiodynamic Scanning electronmicroscopy (SEM)

Performance of Corrosion-Resistant Alloys in Concentrated Acids

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Acta Metallurgica Sinica(English Letters) 2017年第4期30卷 306-318页

作者： ajit Mishra Research and Technology Haynes International 1020 ParkAve Kokomo IN 46902 USA

Nick.l alloys containing optimum amounts of chromium （Cr）, molybdenum （Mo） and tungsten （W） are widely used in the chemical processing industries due to their tolerance to both oxidizing and reducing conditions. Unlik. stainless steel （SS）, Ni-Cr-Mo （W） alloys exhibit remark.bly high uniform corrosion resistance in major concentrated acids, lik. hydrochloric acid （HC1） and sulfuric acid （H2SO4）. A higher uniform corrosion resistance of Ni-Cr-Mo （W） alloys, compared to other alloys, in concentrated acids can be attributed to the formation of protective oxide film of Mo and W in reducing acids, and Cr oxide film in oxidizing solutions. The localized corrosion resistance of Ni-Cr-Mo （W） alloys, containing high amount Cr as well as Mo （or Mo ＋ W）, is also significantly higher than that of other commercially available alloys. The present study investigates the role of alloying elements, in nick.l alloys, to uniform corrosion resistance in concentrated acids （HC1, HC1 ＋ oxidizing impurities and H2SO4） and localized corrosion performance in chloride-rich environments using ASTM G-48 test methodology. The corrosion tests were conducted on various alloys, and the results were analyzed using weight loss technique and electrochemical techniques, in conjunction with surface char- acterization tools.

关键词： Nick.l-chromium-molybdenum-tungsten Corrosion-resistant alloys Reducing acid Oxidants Localized corrosion Surface characterization

Graphene-induced Pd nanodendrites： A high performance hybrid nanoelectrocatalyst

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Nano Research 2013年第9期6卷 635-643页

作者： Subash Chandra Sahu Aneeya k. Samantarat ajit Dash R. R. Juluri Ranjan k. Sahu B. k. Mishra Bik.sh k.mar Jena (1~3) Colloids & Materials Chemistry CSIR-Institute of Minerals and Materials Technology Bhubaneswar-7S I013 India Institute of Physics Bhubaneswar-751005 India Materials Science and Technology Division National Metallurgical Laboratory Jamshedpur-831007 India

A facile and green approach has been developed for the in situ synthesis of hybrid nanomaterials based on dendrite-shaped Pd nanostructures supported on graphene （RG）. The as-synthesized hybrid nanomaterials （RG-PdnDs） have been thoroughly characterized by high resolution transmission electron microscopy, X-ray photoelectron spectroscop）~ atomic force microscop）~ Raman spectroscopy and electrochemical techniques. The mechanism of formation of such dendrite- shaped Pd nanostructures on the graphene support has been elucidated using transmission electron microscopy （TEM） measurements. The RG induces the formation of, and plays a decisive role in shaping, the dendrite morphology of Pd nanostructures on its surface. Cyclic voltammetry and chronoamperometry techniques have been employed to evaluate the electrochemical performance of RG-PdnDs towards oxidation of methanol. The electrochemical （EC） activities of RG-PdnDs are compared with graphene-supported spherical-shaped Pd nanostructures, Pd nanodendrites alone and a commercial available Pd/C counterpart. The combined effect of the graphene support and the dendrite morphology of RG-PdnDs triggers the high electrocatalytic activity and results in robust tolerance to CO poisoning.

关键词： nanodendrites reduced graphene methanol oxidation surface poisoning

Effect of ultrasonic assisted sintering on mechanical properties and degradation behaviour of Mg15Nb3Zn1Ca biomaterial

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Journal of Magnesium and Alloys 2021年第6期9卷 1989-2008页

作者： ajit k.mar Pulak.M Pandey Department of Mechanical Engineering Indian Institute of TechnologyDelhiNew Delhi 110016India

The present work.investigates the effect of ultrasonic power(%)and the time of ultrasonic vibration on the sintered density and ultimate compressive strength(UCS)of Mg15Nb3Zn1Ca fabricated using ultrasonic assisted conventional sintering(UACS).The customized UACS setup was designed and manufactured to conduct the experimentations.A customized ultrasonic stepped horn assembly was used for providing vibrations to the sample during ***,to evaluate the efficacy of ultrasonic vibration parameters,the developed setup was used to sinter Mg15Nb3Zn1Ca composite *** study unveiled an increased sintered density and UCS of the fabricated sample by the increase in ultrasonic power(%).Moreover,a decrease in sintered density and UCS was observed with an increase in the time of ultrasonic vibration beyond a certain *** sintered with the assistance of ultrasonic vibration at 100%ultrasonic power,and 20 min of ultrasonic vibration resulted in a sintered density of 1.928±0.062 g·cm^(-3)and UCS of 234.9±12.3 *** obtained mechanical properties of the fabricated sample were comparable to the properties of cortical *** surface morphology and elemental compositions of samples fabricated using UACS declared a fair dispersion of reinforcement in the matrix containing merely the source *** results of corrosion test have showed that the assistance of ultrasonic vibration suppressed the degradation behaviour of the sintered sample after performing electrochemical study of samples using 3-electorde cell ***15Nb3Zn1Ca fabricated using UACS showed a 50.18%and 9.08%of reduction in corrosion rate over conventionally sintered pure Mg and Mg15Nb3Zn1Ca *** addition,electrochemical impedance spectroscopy(EIS)results indicated an enhanced corrosion resistance of the Mg15Nb3Zn1Ca composite material when fabricated at 100%of ultrasonic power with 20 min of vibration *** from that,electrochemical equivalent circuits also result

关键词： Ultrasonic assisted sintering Magnesium Corrosion EIS Mechanical properties

Variability in physical properties of plantation-grown progenies of Melia composita and determination of a k.ln-drying schedule

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Journal of Forestry Research 2018年第5期29卷 1435-1442页

作者： Shailendra k.mar Bhushan U.k.lk.r ajit k.Mishra Susanta k.Jena Forest Products Division Forest Research Institute

Plantation-grown progenies of Melia composita *** studied for variability in several physical properties： density,radial and tangential shrink.ge,longitudinal permeability of heartwood and ***,flat-sawn plank. from each of the progeny were subjected to a quick.drying test for determination of k.lndrying *** mean density of the species was 0.39 g cm^（-3） and the wood may be categorized as light *** radial shrink.ge（%） for the species was 2.8% with progeny-wise variation in radial shrink.ge from 1.56 to 4.11%.Mean tangential shrink.ge（%） for the species was 5.54% with progeny-wise variation in tangential shrink.ge from 3.69 to 7.71%.The resultant tangentialradial shrink.ge ratio was 1.98（less than two）,which suggests that the wood is relatively stable with respect to drying *** sapwood and heartwood longitudinal permeability of the species were 3.38 and 2.02 Darcy,*** longitudinal permeability of sapwood and heartwood indicate better drying and preservative properties of the *** quick.drying test method suggests that the species is less susceptible to drying *** the test,only moderate check. and crack. were observed.A tentative k.ln-drying schedule was recommended based on these results.

关键词： Melia composita Willd. Density Radial and tangential shrink.ge Longitudinal permeability Quick.rying test k.ln-drying schedule

Examining the policy-practice gap-The issue of crop burning induced Particulate Matter pollution in Northwest India

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Ecosystem Health and Sustainability 2020年第1期6卷 282-297,281页

作者： Leena ajit k.ushal Economics Management Development Institute GurgaonGurugramIndia

The study examine the efficacy of government policy interventions initiated since 2014 to curb FCRB in NW Indian states and the related air pollution in Delhi-NCR during *** regression analysis suggests an increase in PM2.5 of~69μg/m3/1000 surge in *** retrieved data suggest an overall declining trend of~1606 and~4308 fire counts per year across NW states during October-November *** monthly PM2.5 concentrations in New Delhi exhibits a decline of~2.18μg/m3 and~5.17μg/m3 per year over the same *** an overall increase of~17.6%rice productivity,a noted decrease in fire activity over the period is an encouraging move,lik.ly a result of some control imposed by authorities on *** to a significant~35.5%rise in wheat productivity,data records rising trend in wheat residue burning activities in April(~1298/year)and May(~2402/year)but do not trigger extreme pollution due to difference in intensity of fires across harvesting seasons and relatively weak.northwesterly wind ***,the overall high PM2.5 levels in October-November and April-May compared to NAAQS 24-hour average of 60μg/m3,disproves the overall efficacy of government policies to curb FCRB and related air pollution in IGP region.

关键词： Field crop residue burning(FCRB) emissions particulate matter mitigation India government interventions

DEM simulation of polydisperse systems of particles in a fluidized bed

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Particuology 2009年第1期7卷 9-18页

作者： Nobuyuk. Tagami ajit Mujumdar Masayuk. Horio Bio Applications and Systems Engineering Tokyo University of Agriculture & TechnologyNaka-choKoganei-shiTokyo 184-8588Japan

Numerical simulations based on three-dimensional discrete element model （DEM） are conducted for mono-disperse, binary and ternary systems of particles in a fluidized bed. Fluid drag force acting on each particle depending on its size and relative velocity is assigned. The drag coefficient corresponding to Ergun＇s correlation is applied to the system of fluidized bed with particle size ratios of 1：1 for the mono-disperse system, 1：1.2, 1：1.4 and 1：2 for the binary system and 1：1.33：2 for the ternary system by k.eping total volume and surface area of the particles constant. Results indicated that a reasonable estimation of drag force based on individual particle diameters as compared to that of the mean diameter of the particles is achieved in the fluid cells. The total translational k.netic energy of the particles is found to increase as the particle size ratio increases, suggesting an enhanced momentum transfer in polydisperse particle systems. Systems with wide particle size distribution exhibited higher particle velocities around bubbles, resulting in faster bubble growth and its subsequent rise through the fluidized bed.

关键词： Discrete element method Fluid drag force Fluidized bed Particle size distribution