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Defect mediated losses and degradation of perovskite solar cells:Origin impacts and reliable characterization techniques

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Journal of Energy Chemistry 2024年第7期94卷 217-253页

作者： Himangshu Baishy Ramkrishna Das Adhikari Mayur Jagdishbhai Patel Deepak Yadav Tapashi sarmah Mizanur Alam Manab Kalita Parameswar Krishnan lyer Centre for Nanotechnology Indian Institute of Technology GuwahatiGuwahati 781039AssamIndia Department of Chemistry Indian Institute ofTechnology GuwahatGuwahati739AssamIndi

The rapid advancement of halide-based hybrid perovskite materials has garnered significant research attention,particularly in the domain of photovoltaic *** to their exceptional optoelec-tronic properties,they demonstrated power conversion efficiency(PcE)of over 25%in single junction solar *** the notable progress in PCE over the past decade,the inherent high defect density pre-senting in perovskite materials gives rise to several loss mechanisms and associated ion migration in per-ovskite solar cells(PsCs)during operational *** factors collectively contribute to a significant stability challenge in PsCs,placing their longevity far behind for *** numerous reports have explored defects,ion migration,and their impacts on device performance,a com-prehensive correlation between the types of defects and the degradation kinetics of perovskite materials and PsCs has been *** this context,this review aims to provide a comprehensive overview of the origins of defects and ion migration,emphasizing their correlation with the degradation kinetics of per-ovskite materials and PsCs,leveraging reliable characterization ***,these charac-terization techniques are intended to comprehend loss mechanisms by different passivation approaches to enhance the durability and PCE of PSCs.

关键词： Perovskite solar cells Defects lon migration Degradation Stability

Geochemical and petrological studies of high sulfur coal and overburden from Makum 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 Monikankana Saikia Sarat Phukan K.S.V.Subramanyam Ajit Singh Prasenjit Saikia Binoy K.Saikia 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 Makum coalfield,the physico-chemical,geochemical,and petrological characteristics of the coal and overburden(OB)samples collected from the Makum 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 kinetics 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 kinetics.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

Elastoplastic analysis of AA7075-O aluminum sheet by hybrid micro-scale representative volume element modeling with really-distributed particles and in-situ SEM experimental testing

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Journal of Materials Science & Technology 2022年第28期123卷 201-221页

作者： Qingping Sun Shahryar Asqardoust Abhishek sarmah Mukesh K.Jain College of Aerospace and Civil Engineering Harbin Engineering UniversityHarbin 150001China Department of Mechanical Engineering McMaster UniversityHamiltonON L8S4L7Canada

This paper addresses the challenge of reconstructing randomly distributed second-phase particlestrengthened microstructure of AA7075-O aluminum sheet material for computational *** particle characteristics in 3D space were obtained from focused ion beam and scanning electron microscopy(FIB-SEM)and SEM-based Electron Backscatter Diffraction/Energy Dispersive X-ray Spectrometry(EBSD/EDS)techniques.A theoretical framework for analysis of elastic-plastic deformation of such3D microstructures is ***-induced shear band formation,void initiation,growth and linkage at large plastic strains during uniaxial tensile loading were investigated based on reconstructed 3D representative volume element(RVE)models with real-distribution of particles and the results compared with experimental ***-situ SEM interrupted tension tests along transverse direction(TD)and rolling direction(RD),employing microscopic-digital image correlation(μ-DIC)technique,were carried out to investigate slip bands,micro-voids formation and obtain microstructural strain *** resulting local strain maps were analyzed in relation to the experimentally observed plastic flow localization,failure modes and local stress maps from simulations of RVE *** influences of particle size,shape,orientation,volume fraction as well as matrix-particle interface properties on local plastic deformation,global stress-strain/strain-hardening curves and interfacial failure mechanisms were studied based on 3D RVE *** possible,the model results were compared with in-situ tensile test *** general,good agreement was observed,indicating that the real 3D microstructure-based RVE models can accurately predict the plastic deformation and interfacial failure evolution in AA7075-O aluminum sheet.

关键词： Representative volume element AA7075-O aluminum sheet In-situ SEM Microscopic-digital image correlation(μ-DIC) Elastoplastic behavior

Survey of methods and principles in three-dimensional reconstruction from two-dimensional medical images

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Visual Computing for Industry,Biomedicine,and Art 2023年第1期6卷 199-217页

作者： Mriganka sarmah Arambam Neelima Heisnam Rohen Singh Department of Computer Science and Engineering National Institute of TechnologyNagaland 797103India Department of Information Technology Nagaland UniversityNagaland 797112India

Three-dimensional(3D)reconstruction of human organs has gained attention in recent years due to advances in the Internet and graphics processing *** the coming years,most patient care will shift toward this new ***,development of fast and accurate 3D models from medical images or a set of medical scans remains a daunting task due to the number of pre-processing steps involved,most of which are dependent on human *** this review,a survey of pre-processing steps was conducted,and reconstruction techniques for several organs in medical diagnosis were *** methods and principles related to 3D reconstruction were *** usefulness of 3D reconstruction of organs in medical diagnosis was also highlighted.

关键词： Three-dimensional reconstruction Human organ Medical images

Serrated flow accompanied with dynamic type transition of the Portevin-Le Chatelier effect in austenitic stainless steel

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Journal of Materials Science & Technology 2023年第2期133卷 154-164页

作者： Seung-Yong Lee Sita Chettri Ritupan sarmah Chikako Takushima Jun-ichi Hamada Nobuo Nakada Department of Materials Science and Engineering Tokyo Institute of Technology4259 Nagatsuta-choMidori-kuYokohama-shiKanagawa-ken 226-8503Japan Department of Physics Tezpur UniversityNappamTezpur 784028India Research and Development Center Nippon Steel Stainless Steel CorporationHikari 743-8550Japan

In order to further understand high-temperature deformation behavior and its-related mechanical prop-erties,the Portevin-Le Chatelier(PLC)effect in an Fe-19Cr-13Ni-0.2C austenitic stainless steel was in-vestigated using high-temperature digital image correlation(DIC)*** the tensile testing at temperatures from 473 to 623 K,different types of serrated flow appeared even at a constant applied strain rate,and the type transition took place dynamically in a certain order with deformation *** analysis revealed that the dynamic type transition of the serrated flow obeys the PLC band propagation behavior,and that the transition of the PLC band propagation behavior could be attributed to the PLC band nucleation *** modeling also proved that the nucleation manner of PLC band nu-cleation is determined by the spatial-temporal coupling effect.

关键词： Dynamic strain aging(DSA) Austenitic stainless steel(γ-STS) Portevin-Le Chatelier(PLC)effect Digital image correlation(DIC) Local strain distribution

Dynamical study of a predator-prey system with Michaelis-Menten type predator-harvesting

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生物数学学报:英文版 2023年第8期16卷 121-153页

作者： Ankur Jyoti Kashyap Quanxin Zhu Hemanta Kumar sarmah Debasish Bhattacharjee Department of Mathematics Gauhati University AssamIndia Department of Mathematics Assam Royal Global University GuwahatiIndia School of Mathematical Sciences and Statistics Hunan Normal University Changsha410081P.R.China Sajkashyap.maths@***

The predation process plays a significant role in advancing life evolution and the maintenance of ecological balance and *** cooperation in predators is one of the most remarkable features of the predation process,which benefits the predators by developing fear upon their *** study investigates the dynamical behavior of a modified LV-type predator-prey system with Michaelis-Menten-type harvesting of predators where predators adopt cooperation strategy during *** ecologically feasible steady states of the system and their asymptotic stabilities are *** local codimension one bifurcations,***,saddle-node and Hopf bifurcations,that emerge in the system are *** approach is utilized to show the appearance of transcritical bifurcation and saddle-node bifurcation.A backward Hopfbifurcation is detected when the harvesting effort is increased,which destabilizes the system by generating periodic *** stability nature of the Hopf-bifurcating periodic orbits is determined by computing the first Lyapunov *** analyses revealed that above a threshold value of the harvesting effort promotes the coexistence of both *** periodic solutions of the system are also observed when the conversion efficiency rate or the hunting cooperation rate is *** have also explored codimension two bifurcations *** generalized Hopf and the Bogdanov-Takens bifurcation exhibit by the *** visualize the dynamical behavior of the system,numerical simulations are conducted using an ecologically plausible parameter *** existence of the bionomic equilibrium of the model is ***,an optimal harvesting policy for the proposed model is derived by considering harvesting effort as a control parameter with the help of Pontryagins maximum principle.

关键词： Hunting cooperation Michaelis-Menten-type harvesting transcritical and saddle-node bifurcation Hopf bifurcation optimal harvesting policy

Evaluating mechanism and inconsistencies in hydraulic conductivity of unsaturated soil using newly proposed biochar conductivity factor

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Biochar 2023年第1期5卷 585-602页

作者： Ankit Garg Hong-Hu Zhu Ajit K.sarmah Guoxiong Mei Vinay Kumar Gadi Department of Civil and Environmental Engineering Shantou UniversityShantouChina Southwest University of Science and Technology MianyangSichuanChina School of Earth Sciences and Engineering Nanjing UniversityNanjingChina Department of Civil and Environmental Engineering University of AucklandAuckland 1142New Zealand Ocean College Zhejiang UniversityHangzhouChina School of Engineering Cardiff UniversityCardiff CF243AAUK

In the past few decades,numerous studies have been conducted to promote the use of biochar as a soil amendment and most recently,for compacted geo-engineered *** general,the definite trends of biochar effects on water retention and fertility of soils have been ***,the biochar effects on hydraulic conductivity,particularly unsaturated hydraulic conductivity of soil-biochar mix remain unclear,making it difficult to understand water seepage in both agricultural and geo-engineered infrastructures in semi-arid *** study examines the unsaturated hydraulic conductivity function derived based on the measurements of soil water characteristic curves of soil with biochar contents of 0%,5%and 10%.A new parameter“biochar conductivity factor(BCF)”is proposed to evaluate the inconsistency in reported biochar effects on soil hydraulic conductivity and to interpret it from various mechanisms(inter-and intra-pore space filling,cracking,aggregation,bio-film formation and piping/internal erosion).The impact of biochar content on unsaturated hydraulic conductivity appears to reduce as the soil becomes drier with minimal effect in residual *** comparison of near-saturated hydraulic conductivity with test results in the literature showed that the BCF is generally higher for smaller ratio of sand to fine content(clay and silt).Moreover,the particle size of biochar may have significant influence on soil *** scope of research has been highlighted with respect to biochar production for its applications in agriculture and geo-environmental *** term effects such as root decay and growth,aggregation and nutrient supply need to be considered.

关键词： Biochar conductivity factor(BCF) Unsaturated hydraulic conductivity Soil water characteristic curve(SWCC) Pyrolysis process

Spectroscopic Investigation of Black Pepper （Piper nigrum L.）

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Journal of Physical Science and Application 2011年第2期1卷 118-123页

作者： sarmah Pathak Jumisree Gohain Barua Anurup Department of Physics Gauhati University Guwahati 781014 India

Black pepper （Piper nigrum L.） is an extensively used medicinal plant in Ayurvedic medicine since ancient times. Here we present Fourier transform infrared （FT-IR） and Fourier transform Raman （FT-Raman） spectra of black pepper powder, which reveal the presence of some specific functional groups, attributed to the different vibrational bands present. Through the assignment of the vibrational bands, black pepper is shown to have enough carboxyl dimer character, a feature that could make it effective in the treatment of the deadly disease vitiligo. Mineral composition reported with the help of XRF spectra strengthens this.

关键词： Black pepper FT-IR spectrum FT-Raman spectrum XRF spectrum vitiligo.

Investigation of Polyaniline Thin Film and Schottky Junction with Aluminium for Electrical and Optical Characterization

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Materials Sciences and Applications 2011年第8期2卷 1022-1026页

作者： Pronob Jyoti Saikia Pratap Chandra sarmah Department of Electronics North-East Institute of Science and Technology Jorhat Assam India

Polyaniline Powdered sample was chemically synthesized using aniline and doped with HCl. Ultra thin film and Schottky junction with Al metal have been fabricated from this powdered sample Ultrathin film of polyaniline shows amorphous nature of the film. Two activation energies of these films at two different temperatures regions within 25-120oC have been observed. Schottky Junction with Al meal shows that the diode ideality factor is much higher than unity. Barrier height of this Schottky junction is estimated to be around 0.61eV. C-V plot of the junction indicates that the carrier concentration is about 1015cm-3. There are various factors found to affect the junction to deviate from ideal Schottky behaviour.

关键词： Aniline Activation Energy Diode Ideality Factor Barrier Height