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Journal of Rare Earths 2015年第5期33卷 535-544页

作者： Seema verma K.K.Bamzai Crystal Growth and Material Research Laboratory Department of Physics & Electronics University of Jammu

Nanoparticles of neodymium orthophosphate （NdPO4） were prepared through a facile wet co-precipitation technique. The X-ray diffraction （XRD） studies revealed the material belonging to monoclinic monazite phase with crystallite size of 30.8 nm. Scanning electron microscopic studies showed that the material was composed of a large number of agglomerated spherical particles having grain size of 92 nm. Thermogravimetric analysis suggested that the structural phase transition was seen above 800 °C. The spectroscopic investigations were carried out using Fourier transform infrared spectroscopy （FTIR）. UV-VIS-NIR ab-sorption spectrophotometer showed various transitions from the ground state 4I9/2 to various excited states within the 4f shell and the optical band gap came out to be 3.3 eV. The dielectric constant （ε′）, dielectric loss （tanδ） and ac conductivity ln（σac） were measured in the frequency range of 5 kHz to 1 MHz and in the temperature range of 40 to 500 °C. The dielectric measurement suggested that there was a shift in the value of transition temperature （Tc）, thereby indicating relaxor behaviour of the material. The activation energy value decreased with increase in frequency, thereby suggesting the role of mixed ionic-polaronic conduc-tivity.

关键词： nanoparticles spectroscopic dielectric properties rare earths

CaCO_3/TiO_2 Nanoparticles Based Dye Sensitized Solar Cell

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Journal of Materials Science & Technology 2014年第4期30卷 328-334页

作者： Manveen Kaur N.K.verma Nano Research Lab School of Physics and Materials ScienceThapar University

In this communication, the synthesis and structural, morphological, optical, and photo-electrochemical properties of TiO2 and CaCO3/TiO2 nanoparticles as well as their applications in dye sensitized solar cells （DSSCs）, have been reported. In an X-ray diffraction pattern of CaCO3/TiO2 nanoparticles, the peak at 29.41 ° of CaCO3 has been detected, demonstrating its coating on the surface of TiO2, which is further verified using high resolution-transmission electron microscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. The strong quenching in photoluminescence emission, in the case of CaCO3/TiO2 nanoparticles, has been attributed to the decrease in recombination rate of photo-generated electron-hole pairs. In the case of UV-visible reflectance spectra, the absorption edge for CaCO3/TiO2 nanoparticles has slightly been found to be blue-shifted as compared to bare TiO2 nanoparticles, which corresponds to an increase in energy band gap of the former. The dye desorption studies reveal that CaCO3/TiO2 electrodes adsorbed more dye than the bare TiO2 electrode. CaCO3/TiO2 based DSSC show improved photo- electrochemical properties compared to the bare TiO2 based DSSC as CaCO3 coating on mi02 forms an energy barrier, and, consequently suppressing the charge recombination, and, thus, improving the overall energy conversion efficiency （η） from 0.46% to 1.44% under the illumination of simulated light of 100 mW/cm2.

关键词： Dye sensitized solar cells (DSSCs) TiO2 nanoparticles CaCO3 Coating Recombination

Synthesis,Characterization and Biocompatibility of Potassium Ferrite Nanoparticles

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Journal of Materials Science & Technology 2014年第1期30卷 30-36页

作者： Lavanya Khanna N.K.verma Nano Research Lab School of Physics and Materials ScienceThapar University

In the present study, morphology, size distribution, structure, biocompatibility and magnetic properties of potassium ferrite nanoparticles （KFeO2 NPs）, synthesized by conventional sol-gel method have been reported. The formation of spherical nanoparticles with orthorhombic structure has been confirmed by scanning electron microscopy and X-ray diffraction. The particle size, as obtained by transmission electron microscopy has been found to be in the range of 4-7 nm. Further, the size distribution has been scrutinized using Analyse-it software, where a platykurtic feature in the size distribution was observed. Fourier transform-infrared spectroscopy and thermogravimetric analysis showed the formation of metal （Fe, K） bonds at Neel temperature of 337℃. Vibrating sample magnetometer analysis revealed the superparamagnetic behaviour of the synthesized KFeO2 NPs, with saturation magnetization of 25.72 emu/g. In vitro cytotoxicity test, using MTTassay, on T cell lines （Jurkat cells） showed that KFeO2 NPs are biocompatible at a particle concentration of 100μg/ml.

关键词： Potassium ferrite nanoparticles Magnetic nanoparticles Superparamagnetic behaviour Biocompatibility Cytotoxicity

A Cooperative Approach of Frequency Regulation Through Virtual Inertia Control and Enhancement of Low Voltage Ride-through in DFIG-based Wind Farm

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Journal of Modern Power Systems and Clean Energy 2022年第6期10卷 1519-1530页

作者： Preeti verma Seethalekshmi K. Bharti Dwivedi Department of Electrical Engineering Institute of Engineering and TechnologyLucknow 226021Uttar PradeshIndiawhich is a constituent institute of Dr.A.P.J.Abdul Kalam Technical UniversityLucknowUttar Pradesh(U.P.)India IEEE

Doubly-fed induction generator(DFIG)-based wind farms(WFs)are interfaced with power electronic *** interfaces are attributed to the low inertia generated in the WFs under high penetration and that becomes prevalent in a fault ***,transient stability enhancement along with frequency stability in DFIG-based WFs is a major concern in the present *** this paper,a cooperative approach consisting of virtual inertia control(VIC)and a modified grid-side converter(GSC)approach for low voltage ride-through(LVRT)is proposed to achieve fault ride-through(FRT)capabilities as per the grid code requirements(GCRs)while providing frequency support to the grid through a synthetic *** proposed approach provides LVRT and reactive power compensation in the *** participation of the VIC in a rotor-side converter(RSC)provides frequency support to the DFIG-based *** combined approach supports active power compensation and provides sufficient kinetic energy support to the system in a contingency *** studies are carried out in MATLAB/Simulink environment for symmetrical and unsymmetrical *** superiority of the proposed scheme is demonstrated through analysis of the performance of the scheme and that of a series resonance bridge-type fault current limiter(SR-BFCL).

关键词： Virtual inertia controller(VIC) doubly-fed induction generator(DFIG) fault ride-through(FRT)capability wind farm(WF) fault current limiter(FCL)

Endosulfan-mediated Biochemical Changes in the Freshwater Fish Clarias batrachus

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Biomedical and Environmental Sciences 2004年第1期17卷 47-56页

作者： G.TRIPATHI PRIYANKA verma Department of Zoology J.N.V.UniversityJodhpur-342001IndiaDepartment of ZoologyJ.N.V.UniversityJodhpur-342001India

Objective Endosulfan is an extremely toxic organochlorine pesticide to aquatic organisms which might be hampering fish health through impairment of metabolism sometimes leading to death. So an experimental protocol was designed to look at endosulfan effects on a number of selected biochemical endpoints as well as to develop a mechanistic understanding of biochemical effects of endosulfan in freshwater fish. Methods The adult freshwater catfish Clarias batrachus were collected and acclimatized to laboratory condition for two weeks prior to experimentation. The toxicity bioassay test of commercial grade endosulfan (35% EC) was conducted for 21 days to determine its initial lethal concentration. The fish were exposed to sublethal concentration of endosulfan (0.06 mg/L) for 21 days. Pesticide - withdrawal experiments were also performed to study recovery. Protein synthesis inhibitors were injected to know the possible mechanism of recovery. The specimens of C. batrachus were sacrificed and brain, liver and caudal white skeletal muscle were removed. Tissues were homogenized and fractions were obtained by differential centrifugation. The activities of citrate synthase (CS), glucose 6-phosphate dehydrogenase (G6-PDH) and lactate dehydrogease (LDH) were assayed spectrophotometrically. Similarly, DNA, RNA and protein content were measured as per standard procedure. Results The exposure of sublethal concentration of endosulfan decreased the activity of citrate synthase (CS) and glucose 6-phosphate dehydrogenase (G6-PDH) in the brain, liver and skeletal muscle of the freshwater catfish, C. batrachus. The brain lactate dehydrogenase (LDH) activity was also reduced in response to endosulfan toxicity. The maximum reduction in activities of these enzyme was 34%-43%. Withdrawal of endosulfan restored the enzyme activity to control level in all the three tissues. The recovery in enzyme activity appears to be due to dissociation of endosulfan or its metabolite(s) from the enzyme mole

关键词： Catfish Endosulfan CS G6-PDH LDH DNA RNA RNA/DNA ratio and protein

Lossy mode resonance-based uniform core tapered fiber optic sensor for sensitivity enhancement

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Communications in Theoretical Physics 2020年第9期72卷 104-110页

作者： Vikas Keshav Walia R K verma Department of Physics Central University of RajasthanNH-8 BandarsindriAjmer-305817RajasthanIndia Department of Physics DAV UniversityJalandhar-144012PunjabIndia

A lossy mode resonance(LMR)-supported fiber optic sensor in which a uniform fiber core is placed among two identical tapered regions, is investigated numerically. Indium tin oxide(ITO)and aluminum-doped zinc oxide(AZO) are considered as LMR active materials used to excite several lossy modes and gold and silver are used as surface plasmon resonance(SPR) active materials. In this probe design, a central uniform core coated with ITO/AZO is the active sensing region, whereas tapered regions are meant for bringing the incident angle close to the critical angle. The sensitivity of the present fiber optic bio-sensor is evaluated for first two LMRs utilizing both ITO and AZO separately, along with its variation with the taper ratio(TR). For ITO, the maximum sensitivity values are observed to be 18.425 μm RIU^(-1)(refractive index unit)and 0.825 μm RIU^(-1), corresponding to the first and second LMRs, respectively, at a TR of 1.6 and for AZO, equivalent values are 0.79 μm RIU^(-1) and 0.35 μm RIU^(-1), respectively, at a TR of2.0. The results illustrate that the first LMR is more sensitive than the second LMR and the ITOcoated probe possesses greater sensitivity than the AZO-coated probe for both LMRs. Similarly,for the fiber optic SPR sensor, the maximum value of sensitivity is 5.6425 μm RIU^(-1), in the case of gold and 5.0615 μm RIU^(-1) in the case of silver, at a TR of 1.6. Hence, the result shows that the sensor with the present fiber optic probe design has around a 3-fold enhancement in sensitivity compared with conventional SPR sensors. This study will have applications in many sensing schemes where the requirement of large sensitivity is vital.

关键词： fiber optic sensors lossy modes surface plasmons indium tin oxide aluminum-doped zinc oxide sensitivity

Genotoxicity of vegetables irrigated by industrial wastewater

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Journal of Environmental Sciences 2006年第5期18卷 964-968页

作者： Nupur Mathur Pradeep Bhatnagar Hemraj verma Environmental Molecular Microbiology Unit Department of Zoology University of Rajasthan Jaipur 302004 India.

Wastewater effluents from textile dyeing and printing industries of Sanganer are discharged directly, without any treatment, into Amani Shah Nallah drainage. The drainage water takes the dissolved toxicants to flora and fauna, including crops and seasonal vegetables, being grown in the land adjoining the Nallah drainage. Thus mutagenic potential of vegetables irrigated by the water of Amani Shah Nallah drainage was investigated in the present study. The vegetables irrigated by ground water from Sanganer have also been analyzed to determine possible adverse effects of these wastewater effluents on aqua duct.

关键词： sanganer textile wastewaters mutagenicity vegetables Salmonella typhimurium: microsome bioassay

Evaluation of groundwater quality using pollution index of groundwater(PIG) and non-carcinogenic health risk assessment in part of the Gangetic Basin

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Acta Geochimica 2021年第3期40卷 419-440页

作者： Apoorv verma N.B.Singh Environmental Science and Engineering Civil Engineering DepartmentInstitute of Engineering and TechnologyDr.A.P.J.Abdul Kalam Technical UniversityLucknow 226021India Harcourt Butler Technical University Kanpur 208002India

The aim of this study was to evaluate groundwater fitness for domestic and irrigational use in Unnao district of Uttar Pradesh,*** this study,block wise(n=16)groundwater samples were collected,and measured parameters were analyzed using the pollution index of groundwater(PIG),various irrigational indices,and graphical *** results of this study suggested that most of the parameters were within the prescribed limits of WHO and BIS,excluding F-(0.4 to 2.6 mg L^(-1))and Fe^(2+)(0.1 to 1.7 mg L^(-1)).Concentrations of total dissolved solids(TDS)were exceeded the desirable limit(>500 mg L^(-1))in 43.75%of samples at some *** Gibbs plot revealed that groundwater chemistry was governed by rock-water interaction in the region,especially silicate *** Piper plot suggested that Ca^(2+)-HCO3-is dominant hydrochemical facies in the area followed by mixed Ca^(2+)-Na^(+)-HCO_(3)^(-)type,Na^(+)-Cl^(-)type,and Na^(+)-HCO_(3)^(-)*** evaluation revealed that the contribution of F-and Fe2+in groundwater degradation is high in comparison to other elements in the region,about 18.75%samples showed low pollution,while about 6.25%samples shows moderate pollution,and 6.25%samples reflected high *** human health risk(HHR)assessment finding suggested that children(mean:1.36)are more vulnerable than adults(mean:1.01).Sodium absorption ration(SAR),Residual sodium carbonate(RSC),and Permeability index(PI)indicated that most of the groundwater was suitable for irrigation,whereas,Magnesium hazard ration(MHR)and Potential salinity(PS)indices suggested that only 37.5%and 56.25%of the samples were suitable for irrigational use,*** regional study would help in decision making for stakeholders and relevant authorities in the execution of groundwater management and remediation plans in the area.

关键词： Groundwater Pollution index of groundwater Irrigational indices Silicate weathering Human health risk

Axially Oriented Structured Porous Layers for Heat Transfer Enhancement in a Solar Receiver Tube

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Journal of Thermal Science 2021年第5期30卷 1643-1657页

作者： DAS Shefali verma Neha PATHAK Manabendra BHATTACHARYYA Suvanjan Department of Mechanical Engineering Indian Institute of Technology PatnaPatna801103BiharIndia Department of Mechanical Engineering BITS-PilaniPilani333031RajasthanIndia

The present work reports a numerical investigation of heat transfer and pressure drop characteristics in a solar receiver tube with different shaped porous media for laminar and low Reynolds number turbulent flow *** simulations have been performed with finite volume-based code ANSYS(v-2017)for different shapes of porous layers axially oriented in the *** plain-shaped porous medium fitted up to 50%of the tube shows better performance than other-shaped porous *** have also been performed for axially oriented structured porous media with different *** oriented structured porous medium develops a lateral flow disturbance enhancing the intermixing of the liquid and porous medium at their *** porous medium with a 3-crest configuration shows the best heat transfer performance among all the shapes of porous *** offers a maximum of 148%heat transfer enhancement compared to a half-filled plain porous layer,whereas it reports a maximum of 564%enhancement compared to the flow without a porous *** lateral flow tendency or the swirling effect helps better heat transfer performance in the axially oriented structured porous *** evaluation criterion(PEC)in all types of porous media is more in the transitional flow regime than in the laminar and turbulent flow *** the same operating conditions,the maximum value of the PEC in the present work is 120%higher than the maximum value of PEC for other-shaped porous media reported in the *** for Nusselt number have been developed for both laminar and turbulent flow regimes for three crests shaped porous medium.

关键词： porous medium structured porous layer heat transfer enhancement pressure drop performance evaluation criterion

A comprehensive review on energy storage in hybrid electric vehicle

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Journal of Traffic and Transportation Engineering(English Edition) 2021年第5期8卷 621-637页

作者： Shrey verma Shubham Mishra Ambar Gaur Subhankar Chowdhury Subhashree Mohapatra Gaurav Dwivedi Puneet verma Energy Centre Maulana Azad National Institute of TechnologyBhopal 462007India School of Earth and Atmospheric Sciences Queensland University of TechnologyBrisbane 4001Australia

The sharp inclination in the emissions from conventional vehicles contribute to a significant increase in environmental issues,besides the energy crises and low conversion efficiency leads to the evolution of electric vehicles(EV).Hybrid electric vehicles(HEV) have efficient fuel economy and reduce the overall running cost,but the ultimate goal is to shift completely to the pure electric *** this,the main obstruction of HEV is energy storage *** EV requires high specific power(W/kg) and high specific energy(W$h/kg) to increase the distance travelled and reduce the time required for *** main focus of this paper is on the energy sources as these are the main components in EVs towards making them eco-friendly and *** topologies of EV technology such as HEVs,plug-in HEVs,and many more have been *** topologies of EVs are based on the diverse combination of batteries,fuel cells,super-capacitor,flywheels,regenerative braking systems,which are used as energy sources and energy storage devices.

关键词： Electric vehicle Energy storage Battery electric vehicle Hybrid electric vehicles