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Preparation of NiFe_2O_4 nanopowder via EDTA precursor and study of its properties

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Particuology 2012年第1期10卷 29-34页

作者： Amit b.Rajput Subhenjit Hazra Niharika b.krishna Pavani Chavali Sneha Datla Narendra Nath Ghosh Nano-Materials Lab Department of Chemistry BITS-Pilani K.K. Birla Goa Campus

An ethylene diamine tetra acetic acid （EDTA） precursor-based chemical method is reported for prepar- ing single-phase nickel ferrite （NiFe204） nanopowder. The synthesized powder was characterized by thermogravimetric analysis, differential scanning calorimetric analysis, X-ray diffraction, particle size analysis and scanning electron microscopy. DC electrical resistivity and magnetic property of the synthesized NiFe204 were measured by using a two-probe method and a vibrating sample magnetometer respectively. The DC resistivity behaviour of the NiFe204 nanopowder was correlated with the change of microstructure, during sintering. This EDTA precursor-based method is capable of producing nanos- tructured single-phase NiFe204 powder at a comparatively low calcination temperature and offers the potential of a simple and cost-effective route, including the preparation of other ferrite nanoparticles.

关键词： Magnetic materialsChemical synthesisX-ray diffractionMagnetic properties

bRUCK FORMULA FOR A PERTURbED LIPSCHITZIAN ITERATION OF LIPSCHITZ PSEUDOCONTRACTIVE MAPS

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Applied Mathematics and Mechanics(English Edition) 2005年第11期26卷 1427-1434页

作者： krishna kumar b. K. Sharma ZHOU Zhe-wei School of Studies in Mathematics Pt. Ravishankar Shukla University Raipur Chhattisgarh-492010 India 不详

The solution to evolution equations has developed an independent theory within nonlinear analysis dealing with the existence and approximation of such solution （ fixed point） of pseudocontractive operators and its variants. The object is to introduce a perturbed iteration method for proving the convergence of sequence of Lipschitzian pseudocontractive mapping using approximate fixed point technique. This iteration can be ued for nonlinear operators which are more general than Lipschitzian pseudocontractive operator and bruck iteration fails for proving their convergence. Our results generalize the results of Chidume and Zegeye.

关键词： pseudocontractive map perturbed Lipschitzian iteration fixed point uniformaly Gateaux differential norm

A threshold voltage model of short-channel fully-depleted recessed-source/drain(Re-S/D) SOI MOSFETs with high-k dielectric

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Chinese Physics b 2015年第10期24卷 604-611页

作者： Gopi krishna Saramekala Sarvesh Dubey Pramod kumar Tiwari Department of Electronics and Communication Engineering National Institute of Technology Shri Ramswaroop Memorial University

In this paper, a surface potential based threshold voltage model of fully-depleted（FD） recessed-source/drain（Re-S/D）silicon-on-insulator（SOI） metal-oxide semiconductor field-effect transistor（MOSFET） is presented while considering the effects of high-k gate-dielectric material induced fringing-field. The two-dimensional（2D） Poisson＇s equation is solved in a channel region in order to obtain the surface potential under the assumption of the parabolic potential profile in the transverse direction of the channel with appropriate boundary conditions. The accuracy of the model is verified by comparing the model＇s results with the 2D simulation results from ATLAS over a wide range of channel lengths and other parameters,including the dielectric constant of gate-dielectric material.

关键词： recessed-source/drain (Re-S/D) high-k gate-material fringing field and SCEs

Design and Robustness Analysis of a Wave-based Controller for Tethered Towing of Defunct Satellites

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IEEE/CAA Journal of Automatica Sinica 2023年第1期10卷 278-280页

作者： Rui Qi Yang Zhang krishna D.kumar the School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China IEEE the Department of Aerospace Engineering Ryerson UniversityToronto M5B 2K3Canada

Dear Editor, A microgravity environment in space, the elasticity of the tether,and complex flexible appendages make the tethered-towing system a nonlinear and underactuated system, which is sensitive and difficult to stabilize. This letter develops a controller based on wave propagation for tethered towing of defunct satellites, and carries out a robustness analysis of the controller via numerical simulation.

关键词： system elasticity letter

Perturbations in Earth’s Atmosphere over An Indian Region during the Total Solar Eclipse on 22 July 2009

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Journal of Meteorological Research 2019年第4期33卷 784-796页

作者： S.b.Surendra PRASAD Vinay kumar K.krishna REDDY S.K.DHAKA Shristy MALIK M.Venkatarami REDDY U.Murali krishna Semi-arid-zone Atmospheric Research Centre(SARC) Department of PhysicsYogi Vemana UniversityKadapaAndhra Pradesh 516003India Radio and Atmospheric Physics Lab Rajdhani CollegeUniversity of DelhiDelhi 110015India Department of Applied Physics Delhi Technical UniversityDelhi 110042India

During a total solar eclipse(TSE)on 22 July 2009,atmospheric perturbations were monitored from the surface to thermosphere to understand TSE’s impact on the meteorological(temperature,relative humidity,wind speed,and wind direction)and chemical(O3 and NOx)parameters around Kadapa(14.28°N,78.42°E),a tropical semi-arid region of *** this purpose,an experiment was conducted at Yogi Vemana University Campus,Kadapa,India,to measure the temperature,wind speed,wind direction,and concentrations of ozone(O3),NO,NO2,and NOx by using the automatic weather station(AWS)and O3 *** the eclipse day(22 July 2009),the surface observations at Kadapa showed a reduction in temperature(about 1.1℃)because of the solar *** of the thermal,dynamical(wind),and chemical parameters on the TSE day with control days[preceding(21 July 2009)and succeeding(23 July 2009)the TSE]illustrated the influence of solar *** the eclipse period,the O3 mixing ratio decreased,while NO2 and NOx increased;however,NO remained *** addition,radio occultation(RO)temperature profiles from Constellation Observing System for Meteorology,Ionosphere,and Climate(COSMIC)/Formosat Satellite Mission(FORMOSAT-3)and Thermosphere,Ionosphere,and Mesosphere Energetics and Dynamics(TIMED)satellites were utilized to understand the impact of TSE on dynamics of the middle and upper atmosphere from tropopause to the *** vertical resolution COSMIC observations revealed that during the solar eclipse,tropopause was cooler with twin peaks(double tropopause).The lower thermosphere between 110 and 130 km became warmer during the TSE,which might be caused by the dynamical response of the atmosphere in this region to the solar *** experimental data have provided very fine-scale variations of the atmospheric parameters both in time and height and also constituted a new set of results on TSE for further research.

关键词： total solar eclipse (TSE) atmospheric perturbations tropopause dynamics COSMIC/FORMOSAT-3satellite radio occultation (RO) observations

Impact of Cyclone Nilam on Tropical Lower Atmospheric Dynamics

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Advances in Atmospheric Sciences 2016年第8期33卷 955-968页

作者： P.VINAY kumar Gopa DUTTA M.V.RATNAM E.krishna b.bAPIRAJU b.Venkateswara RAO Salauddin MOHAMMAD Vignana bharathi Institute of Technology HyderabadTS 501301India National Atmospheric Research Laboratory GadankiAP 517112India Jawaharlal Nehru Technological University HyderabadTS 500085India

A deep depression formed over the bay of bengal on 28 October 2012, and developed into a cyclonic storm. After landfall near the south coast of Chennai, cyclone Nilam moved north-northwestwards. Coordinated experiments were conducted from the Indian stations of Gadanki（13.5？N, 79.2？E） and Hyderabad（17.4？N, 78.5？E） to study the modification of gravity-wave activity and turbulence by cyclone Nilam, using GPS radiosonde and mesosphere–stratosphere–troposphere radar data. The horizontal velocities underwent large changes during the closest approach of the storm to the experimental sites. Hodograph analysis revealed that inertia gravity waves（IGWs） associated with the cyclone changed their directions from northeast（control time） to northwest following the path of the cyclone. The momentum flux of IGWs and short-period gravity waves（1–8 h） enhanced prior to, and during, the passage of the storm（±0.05 m2s-2and ±0.3 m2s-2, respectively）, compared to the flux after its passage. The corresponding body forces underwent similar changes, with values ranging between ±2–4m s-1d-1and ±12–15 m s-1d-1. The turbulence refractivity structure constant（C2n） showed large values below 10 km before the passage of the cyclone when humidity in the region was very high. Turbulence and humidity reduced during the passage of the storm when a turbulent layer at ～17 km became more intense. Turbulence in the lower troposphere and near the tropopause became weak after the passage of the cyclone.

关键词： inertia gravity waves turbulence momentum flux convective process tropical cyclone

Hepatoprotective activity of Hepax-A polyherbal formulation

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Asian Pacific Journal of Tropical biomedicine 2011年第2期1卷 142-146页

作者： VC Devaraj b Gopala krishna GL Viswanatha Jagadish V Kamath Sanjay kumar Department of Pharmacology Krupanidhi College of Pharmacy Department of Pharmacognosy RR College of Pharmacy Department of Pharmacology PES College of Pharmacy

Objective:To evaluate the hepatoprotective potential of Hepax,a polyherbal formulation,against three experimentally induced hepatotoxicity models in ***:Hepatoprotective activity of Hepax was studied against three experimentally induced hepatotoxicity models,namely, carbon tetrachloride(CCl_4),paracetamol and thiocetamide induced hepatotoxicity in rats. Results:Administration of hepatotoxins(CCl_4,paracetamol and thiocetamide) showed significant morphological,biochemical and histological deteriorations in the liver of experimental animals. Pretreatment with Hepax had significant protection against hepatic damage by maintaining the morphological parameters(liver weight and liver weight to organ weight ratio) within normal range and normalizing the elevated levels of biochemical parameters(SGPT,SCOT,ALP and total bilirubin),which were evidently showed in histopathological ***:The Hepax has highly significant hepatoprotective effect at 100 and 200 mg/kg,*** the liver of all the three experimental animal models.

关键词： Hepax Paracetamol CCl_4 Thiocetamide Hepatotoxicity

Effect of Flow Field Geometry on Hydrodynamics of Flow in Redox Flow battery

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Energy Engineering 2022年第1期119卷 201-217页

作者： M.Narendra kumar S.Manoj kumar G.C.Vijayakumar K.Kadirgama M.Samykano krishna Venkatesh H.b.Murlidhara Center for Incubation Innovation Research and Consultancy(CIIRC)Jyothy Institute of TechnologyBangalore560082KarnatakaIndia Department of Mechanical Engineering Jyothy Institute of TechnologyBangalore560082KarnatakaIndia Faculty of Mechanical and Automotive Engineering Technology University Malaysia PahangPahang26600Malaysia Centre for Automotive Engineering Universiti Malaysia PahangPahang26600Malaysia College of Engineering Universiti Malaysia PahangPahang26600Malaysia

This study computationally investigates the hydrodynamics of different serpentine flow field designs for redox flow batteries,which considers the Poiseuille flow in the flow channel and the Darcy flow porous *** Fluid Dynamics(CFD)results of the in-house developed code based on Finite Volume Method(FVM)for conventional serpentine flow field(CSFF)agreed well with those obtained via *** deviation for pressure drop(ΔP)was less than 5.1%for all the flow rates,thus proving the present CFD analysis’s validity on the modified variation of serpentine flow *** serpentine flow field-2(MSFF2)design provided least pressure drop across the channel and maximum velocity penetration across the porous substrate when compared to the other *** increases its wetting ability,which is very important in terms of mass transfer over potential for electrochemical reaction happening in the porous substrate to achieve effective electrochemical cell performance.

关键词： Pressure drop velocity distribution serpentine flow field porous substrate redox flow battery

Post-stroke mRNA expression profile of MMPs:effect of genetic deletion of MMP-12

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Stroke & Vascular Neurology 2018年第3期3卷 153-159页

作者： Koteswara Rao Nalamolu bharath Chelluboina Ian b Magruder Diane N Fru Adithya Mohandass Ishwarya Venkatesh Jeffrey D Klopfenstein David M Pinson krishna M boini krishna kumar Veeravalli Department of Cancer biology and Pharmacology University of Illinois College of MedicinePeoriaIllinoisUSA Department of Neurosurgery University of Illinois College of MedicinePeoriaIllinoisUSA Comprehensive Stroke Center Illinois Neurological InstituteOSF HealthCare SystemSaint Francis Medical CenterPeoriaIllinoisUSA Department of Pathology University of Illinois College of MedicinePeoriaIllinoisUSA Department of Pharmacological and Pharmaceutical Sciences College of PharmacyUniversity of HoustonHoustonTexasUSA Department of Neurology University of Illinois College of MedicinePeoriaIllinoisUSA

background and purpose Recent reports from our laboratory demonstrated the post-ischaemic expression profile of various matrix metalloproteinases(MMPs)in rats and the detrimental role of MMP-12 in post-stroke brain *** hypothesise that the post-stroke dysregulation of MMPs is similar across species and that genetic deletion of MMP-12 would not affect the post-stroke expression of other *** tested our hypothesis by determining the pre-ischaemic and post-ischaemic expression profile of MMPs in wild-type and MMP-12 knockout *** Focal cerebral ischaemia was induced in wildtype and MMP-12 knockout mice by middle cerebral artery occlusion procedure by insertion of a monofilament *** hour after ischaemia,reperfusion was initiated by removing the *** day after reperfusion,ischaemic brain tissues from various groups of mice were collected,and total RNA was isolated and subjected to cDNA synthesis followed by PCR *** Although the post-stroke expression profile of MMPs in the ischaemic brain of mice is different from rats,there is a clear species similarity in the expression of MMP-12,which was found to be predominantly upregulated in both ***,the post-stroke induction or inhibition of various MMPs in MMP-12 knockout mice is different from their respective expression profile in wild-type ***,the brain mRNA expression profile of various MMPs in MMP-12 knockout mice under normal conditions is also different to their expression in wild-type *** In the ischaemic brain,MMP-12 upregulates several fold higher than any other *** derived with the genetic deletion of MMP-12 are constitutive and have altered MMP expression profile both under normal and ischaemic conditions.

关键词： MMPs removing hypothesis