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Structural and micro structural studies of PbO-doped SnO_2 sensor for detection of methanol, propanol and acetone

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Journal of Natural Gas Chemistry 2011年第2期20卷 179-183页

作者： J. k. srivastava Preeti Pandey V. N. Mishra r. Dwivedi Center for research in Microelectronics Department of Electronics Engineering Institute of Technology Banaras Hindu University

In the present work the structural information of PbO-doped SnO2 thick film sensor has been investigated with X-ray diffractometer （XrD） and scanning electron microscope （SEM）. Initially, SnO2 powder was derived using sol-gel process and was subsequently doped with PbO and ground up to nanosized particles. A suitable gas sensor structure was fabricated on 1′′×1′′ alumina substrate using thick film technology. The necessary paste for screen printing was also developed. SEM results showed sol-gel derived powder gets more agglomerated in the thick film form. The sensitivity of the sensor has been investigated at different temperatures （150 ？C？350 ？C） upon exposure to methanol, propanol and acetone, yielding a maximum at 250 ？C for acetone with 1 wt% PbO-doping while at 350 ？C for propanol with 3 wt% PbO-doping of the sensor. The reduction of particle size to nanometers （validated through XrD） leads to a dramatic improvement in sensitivity of sensors for the chosen organic vapors. The results also correlate well with the microstructural properties of the material and the dopant.

关键词： gas sensor nanosized SnO2 Sol-gel thick film

Long-term impact of artificial intelligence on colorectal adenoma detection in high-risk colonoscopy

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World Journal of Gastrointestinal Endoscopy 2024年第6期16卷 335-342页

作者： kenneth W Chow Matthew T Bell Nicholas Cumpian Maryanne Amour ryan H Hsu Viktor E Eysselein Neetika srivastava Michael W Fleischman Sofiya reicher Department of Medicine Harbor-UCLA Medical CenterTorranceCA 90502United States Department of Bioengineering Jacobs School of EngineeringUniversity of CaliforniaSan DiegoLa JollaCA 92093United States Department of Gastroenterology Harbor-UCLA Medical CenterTorranceCA 90502United States

BACkGrOUND Improved adenoma detection rate(ADr)has been demonstrated with artificial intelligence(AI)-assisted ***,data on the real-world appli-cation of AI and its effect on colorectal cancer(CrC)screening outcomes is *** To analyze the long-term impact of AI on a diverse at-risk patient population undergoing diagnostic colonoscopy for positive CrC screening tests or *** AI software(GI Genius,Medtronic)was implemented into the standard proced-ure protocol in November *** was collected on patient demographics,procedure indication,polyp size,location,and *** screening outcomes were evaluated before and at different intervals after AI introduction with one year of *** We evaluated 1008 colonoscopies(278 pre-AI,255 early post-AI,285 established post-AI,and 190 late post-AI).The ADr was 38.1%pre-AI,42.0%early post-AI(P=0.77),40.0%established post-AI(P=0.44),and 39.5%late post-AI(P=0.77).There were no significant differences in polyp detection rate(PDr,baseline 59.7%),advanced ADr(baseline 16.2%),and non-neoplastic PDr(baseline 30.0%)before and after AI *** In patients with an increased pre-test probability of having an abnormal colonoscopy,the current generation of AI did not yield enhanced CrC screening metrics over high-quality *** the potential of AI in colonoscopy is undisputed,current AI technology may not universally elevate screening metrics across all situations and patient *** studies that analyze different AI systems across various patient populations are needed to determine the most effective role of AI in optimizing CrC screening in clinical practice.

关键词： Artificial intelligence Colonoscopy Adenoma detection rate Screening Colorectal adenoma

Controlling Diffusion by Varying Width of Layers in Nano Channel

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Nano-Micro Letters 2012年第3期4卷 154-157页

作者： Ishu Goyal Sunita srivastava k.Tankeshwar Department of Physics Panjab University Computer Centre Panjab University

Diffusive dynamics of fluid forming layers of high and low density regions in a nanochannel has been *** coefficient in direction parallel and perpendicular to the confining wall has been found to show behaviour which is not observed in micro channel or bulk *** behaviour of diffusion is found to be controlled by the width of layers formed in nanochannel due to wall and particle *** is an important result as width of layers and hence flow of fluid inside nano pores/tube can be controlled by an external source.

关键词： Nanochannel Layer Diffusion

Compositionally Graded Microstructure for Ag-Fe Nanoparticles

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Nano-Micro Letters 2012年第3期4卷 172-175页

作者： Chandan srivastava k.V.L.Sushma Department of Materials Engineering Indian Institute of Science

Ag-Fe nanoparticles with a highly Ag rich average composition were synthesized by the sonochemical ***-iron system exhibits a wide miscibility gap in the bulk ***,a graded compositional profile along the nanoparticle radius was *** at and near the surface of the nanoparticle contained both Ag and Fe *** composition got relatively deficient Fe towards the center of the particle with particle core made up of pure *** of Ag and Fe is confirmed by the absence of diffraction signal corresponding to pure Fe phase and presence of a paramagnetic phase in nanoparticles containing a diamagnetic(Ag)and ferromagnetic(Fe)elements.

关键词： Nanoparticles Electron Microscopy Ag-Fe Miscibility gap Solid solution Microstructure

Legumes from the Paleocene sediments of India and their ecological significance

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Plant Diversity 2023年第2期45卷 199-210页

作者： Harshita Bhatia Gaurav srivastava r.C.Mehrotra Birbal Sahni Institute of Palaeosciences 53 University RoadLucknow 226007India Academy of Scientific and Innovative research(AcSIr) Ghaziabad 201002India

During the early Paleogene,greenhouse gases created warm global *** warm climates redistributed the habitat of marine and terrestrial biota *** the ecology of biotas under extremely warm climates is important to decipher their behavior in future climate *** we report two new legume fossils(Leguminocarpum meghalayensis Bhatia,srivastava et Mehrotra ***.,and Parvileguminophyllum damalgiriensis Bhatia,srivastava et Mehrotra ***.) from the late Paleocene sediments of Tura Formation of Meghalaya,northeast ***,the Paleocene legume fossil records indicate that legumes most likely immigrated to India from Africa via the Ladakh-kohistan Arc during the early ***,previously reconstructed climate data from the Tura Formation indicate that legumes were well adapted to a warm seasonal climate with monsoon rains.

关键词： Fabaceae Global warming Fruits Damalgiri Tura rhynchosia

Seasonal Inhomogeneity of Soot Particles over the Central Indo-Gangetic Plains,India:Influence of Meteorology

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Journal of Meteorological research 2015年第6期29卷 935-949页

作者： SINGH B.P. TIWArI S. HOPkE Philip k. SINGH r.S. BISHT D.S. srivastava A.k. SINGH r.k. DUMkA U.C. SINGH A.k. rAI B.N. srivastava Manoj k. Department of Geophysics Banaras Hindu University Indian Institute of Tropical Meteorology(New Delhi Branch) Clarkson University Department of Chemical Engineering Banaras Hindu University Aryabhatta research Institute of Observational Sciences Department of Physics Banaras Hindu University

Black carbon（BC） particles play a unique and important role in earth’s climate *** was measured（in-situ） in the central part of the Indo-Gangetic Plains（IGP） at Varanasi,which is a highly populated and polluted region due to its topography and extensive emission *** annual mean BC mass concentration was 8.92 ± 7.0 μg m-3,with 34%of samples exceeding the average ***,BC was highest during the post-monsoon and winter periods（approximately 18 μg m-3） and lower in the premonsoon/monsoon seasons（approximately 6 μg m-3）.The highest frequency（approximately 46%） observed for BC mass was in the interval from 5 to 10 μg ***,during the post-monsoon season,the most common values（approximately 23%） were between 20 and 25 μg *** nighttime concentrations of BC were approximately twice as much as the daytime values because of lower boundary layer heights at *** Angstrom exponent was significantly positively correlated（0.55） with ground-level BC concentrations,indicating the impact of BC on the columnar aerosol *** estimated mean absorption Angstrom exponent was 1.02 ± 0.08 μg m-3,indicating that the major source of BC was from fossil fuel *** negative correlations between BC mass and meteorological parameters indicate a pronounced effect of atmospheric dynamics on the BC mass in this *** highest mean BC mass concentration（18.1 ± 6.9 μg m-3） as a function of wind speed was under calm wind conditions（38%of the time）.

关键词： black carbon Indo-Gangetic Plains absorption Angstr(o|¨)m exponent biomass fossil fuel

review of near-shore satellite derived bathymetry: Classification and account of five decades of coastal bathymetry research

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Journal of Ocean Engineering and Science 2021年第4期6卷 340-359页

作者： Mohammad Ashphaq Pankaj k srivastava D Mitra National Hydrographic Office DehradunIndia University of Petroleum&Energy Studies(UPES) DehradunIndia Indian Institute of remote Sensing DehradunIndia

The number of civilian,commercial and military applications are dependant on accurate knowledge of bathymetry of coastal ***,hydrographic surveying methods are used for bathymetric surveys carried by ship-based acoustic systems,but needs highcost *** technology has provided a cost-effective alternate means for charting near shore and inaccessible *** optical satellite data have capabilities to offer alternate solution in near-shore region,which has been researched for past 50 years,using evolving algorithms to estimate Satellite Derived Bathymetry(SDB).However,there is no agreement on use of terms like approach,model,method and techniques,which have been used varyingly and interchangeably as per context of SDB *** paper suggests a classification scheme for SDB algorithms which is also applicable to other Marine remote Sensing *** this paper,based on literature available on SDB for the past five decades,an insight on SDB classification has been offered grounded in research *** SDB approaches,models,methods and techniques have been elaborated with chronological development,along with SDB studies based on them,their accuracy and errors in SDB *** have suggested a matrix of prerequisite satellite data,in-situ data resolution,methods and algorithms of SDB based on level of accuracy needs to be achieved,which will guide future researchers to select one as per their context of research.

关键词： Satellite derived bathymetry Hydrography Bio-optical model Physio-optical model

Application of IITM-rANS3D to free-fall water entry of prismatic and non-prismatic finite wedges

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水动力学研究与进展B辑:英文版 2023年第3期35卷 417-430页

作者： Shaswat Saincher kshitij srivastava r.Vijayakumar V.Sriram Center for Maritime Experiments to Maritime Experience(ME2ME) Indian Institute of Technology MadrasChennaiIndia Department of Ocean Engineering Indian Institute of Technology MadrasChennaiIndia

High-speed watercraft and ships undergo coupled motions which make the front portion of the hull exit and violently re-enter *** induces short-term slamming loads that may compromise the structural integrity of the *** slamming of the bow can be modeled as straight wedges of different deadrise angles(DrAs)falling into water from different *** advent of computational fluid dynamics has allowed the problem of wedge-slamming to be simulated using the full Navier-Stokes equations thus complementing the pioneering studies based on ***,most researchers are opting to use commercial software to simulate the wedge-impact problem as it allows access to overset meshing algorithms which are robust in modeling the wedge as a moving *** boundary methods(EBMs)offer some advantages over overset meshing in that the mesh only needs to be generated once and Cartesian mesh-based solvers can be ***,the application of EBMs to wedge-impact has been limited in the literature and merits further *** this context,we investigate the applicability of the fast-fictitious-domain(FFD)based embedded boundary treatment to simulate the violent water-entry of *** extend our in-house Navier-Stokes model IITM-rANS3D to handle floating bodies through integration of a rigid-body dynamics solver and an algorithm to embed three-dimensional stereolithography(STL)geometries as solids over a Cartesian *** proposed algorithm is extensively benchmarked against variable DrA wedge-slamming experiments reported in the literature as well as constant DrA wedge-slamming experiments performed *** good agreement is reported in terms of the time-history of hydrodynamic impact pressures measured at various locations on the hull as well as the wedge motion responses thus demonstrating the suitability of FFD for simulating the coupled hydrodynamics of slamming for simplified hull geometries.

关键词： Wedge water entry slamming fast-fictitious-domain IITM-rANS3D experiments

radiation Losses in the Microwave X Band in Al-Cr Substituted Y-Type Hexaferrites

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Chinese Physics Letters 2017年第4期34卷 35-38页

作者： D.Basandrai r.k.Bedi A.Dhami J.Sharma S.B.Narang k.Pubby A.k.srivastava research Scholar Department of Physics I. K. Gujral Punjab Technical University Jalandhar India Department of Physics Lovely Professional University Phagwara India principal Satyam Institute of Engineering & Technology Amritsar India Department of Electronic Technology Guru Nanak Dev University Amritsar India

We present a study on radiation losses in the microwave X band in Al-Cr substituted Y-type hexaferrites, namely Ba2Mg2Alx/2Crx/2Fe12-xO22 （x = 0, 0.5 and 1.0）. The study is performed by means of a vector network analyzer, Fourier transform infrared spectroscopy, a vibrating sample magnetometer and x-ray powder diffraction. Ba2Mg2Fe12O22 hexaferrite shows radiation loss of -37.25dB （99.999% loss） at frequency 9.81 GHz, which can be attributed to its high value of saturation magnetization, i.e., 22.08emu/g. Moreover, we obtain that magnetic properties have strong influence on the radiation losses.

关键词： Ba Al radiation Losses in the Microwave X Band in Al-Cr Substituted Y-Type Hexaferrites Cr