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Formation characterization and rheological properties of zirconia and ceria-stabilized zirconia

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Natural Science 2010年第7期2卷 694-706页

作者： arvind k. nikumbh Parag V. Adhyapak 不详

Zirconia and ceria-stabilized zirconia (12Ce-TZP) were synthesized by the dicarboxylate coprecipitation technique such as fumarate, succinate, tartarate and adipate. The formation of these dicarboxylate precursors was studied by elemental analysis, thermal analysis and infrared spectroscopy. The precursors were further decomposed at 650oC for 2 hours to form respective zirconia and ceria-stabilized zirconia. The composition of these oxides was check.d by Atomic absorption spectrometer and Energy dispersive X-ray analysis. The structural and morphological characterization of these oxides was done by using X-ray diffraction analysis, surface area, scanning electron micrographs and particle size distribution analysis. These properties were found depending to great extent on the nature of the precursors. The zirconia and ceria-stabilized zirconia obtained from adipate precursor were found to be good for slip- casting. The slips (i.e., suspensions) of these oxides with different solid contents were prepared at different pH with distilled water and ethanol as dispersing agents, with and without deflocculant. The suspension rheological flow (i.e., variation of shear stress and viscosity with shear rate) was determined. The minimum viscosities were observed at pH = 10.16 for ZrO2- water and pH = 10.26 for 12Ce–TZP-water system. The slip, green and sedimentation bulk.density were measured.

关键词： Oxides Ceramics Chemical Synthesis Surface Properties

Impedance and ferroelectric properties of Sr^(2+) modified PZT-PMN ceramics

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International Journal of Minerals,Metallurgy and Materials 2014年第6期21卷 595-603页

作者： arvind k.mar S.k.Mishra Research and Technology Development Centre Sharda University Dr. Harisingh Gour University

Sr^2＋ modified polycrystalline PZT-PMN ceramics were synthesized by a semi-wet route. Impedance spectroscopy studies indicate the bulk.and grain boundary effects of PZT-PMN material along with the negative temperature coefficient of resistance. The bulk.conductiv-ity exhibits an Arrhenius-type thermally activated hopping process which is supported by the AC conductivity behavior as a function of fre-quency and temperature. It is observed that the remnant polarization increases with an increase in the Sr2＋content in PZT-PMN.

关键词： piezoelectric ceramics ferroelectric materials ferroelectricity electrochemical properties strontium

Intensification of photocatalytic decomposition of water by ultrasound

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Journal of Energy Chemistry 2018年第4期27卷 1183-1188页

作者： arvind Singh A.S.k.Sinha Department of Chemical Engineering and Technology Indian Institute of Technology (Banaras Hindu University)

Photocatalysis of water with and without ultrasound was studied using rGO supported CdS catalyst utilizing visible light. A higher hydrogen production was observed when ultrasound was used. This is attributed to a faster removal of bubbles of hydrogen from the surface of photocatalyst due to the mechanical energy associated with ultrasound overcoming surface tension. It has been further reported that the rate of hydrogen production decreased with time due to reversible deactivation of catalyst. This has been attributed to decrease in rate of hydrogen desorption with time.

关键词： Hydrogen Photocatalysis Ultrasound k.netics

Effects of Sr^(2+) substitution on the structural, dielectric, and piezoelectric properties of PZT-PMN ceramics

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International Journal of Minerals,Metallurgy and Materials 2014年第2期21卷 175-180页

作者： arvind k.mar S.k. Mishra Research and Technology Development Centre Sharda University

This study described the structural, dielectric, and piezoelectric behavior of Pb1-xSrx[（Zr0.52Ti0.48）0.95（Mn1/3Nb2/3）0.05]O3 ceramics （PSZT-PMN, x=0, 0.025, 0.050, and 0.075）, prepared by a semi-wet route. X-ray diffraction, dielectric, and piezoelectric investigations were carried out to analyze the crystal structure. The relative dielectric constant and dielectric loss were both calculated as the functions of temperature. The room-temperature dielectric constant reaches a maximum for a Sr2＋-modified PZT-PMN ceramic with an x value of 0.050, which corresponds to the morphotropic phase boundary （MPB）. Raman spectroscopy studies also confirm the existence of this MPB for x=0.050. The piezoelectric strain coefficients （d33） value shows a maximum response for this composition. In addition, the phase transition temperature decreases significantly when the Sr2＋concentration increases in the PZT-PMN ceramics.

关键词： ceramic materials strontium substitution structural properties dielectric properties piezoelectricity

Dielectric, piezoelectric, and ferroelectric properties of lanthanum-modified PZTFN ceramics

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International Journal of Minerals,Metallurgy and Materials 2014年第10期21卷 1019-1027页

作者： arvind k.mar S.k.Mishra Research and Technology Development Centre Sharda University Dr. Harisingh Gour University

Specimens of Pb1-1.5xLax（Zr0.53 Ti0.47）1-y-zFeyNb2O3 （x = 0, 0.004, 0.008, 0.012, and 0.016, y = z = 0.01）（PZTFN） ceramics were synthesized by a semi-wet route. In the present study, the effect of La doping was investigated on the structural, microstructural, dielectric, piezoelectric, and ferroelectric properties of the ceramics. The results show that, the tetragonal （space group P4mm） and rhombohedral （space group R3c） phases are observed to coexist in the sample at x = 0.012. Microstructural investigations of all the samples reveal that La doping inhibits grain growth. Doping of La into PZTFN improves the dielectric, ferroelectric, and piezoelectric properties of the ceramics. The hys- teresis loops of all specimens exhibit nonlinear behavior. The dielectric, piezoelectric and ferroelectric properties show a maximum response atx 〉 0.012, which corresponds to the morphotropic phase boundary （MPB）.

关键词： ceramics lanthanum doping dielectric properties piezoelectricity ferroelectricity Rietveld refinement hysteresis loops

Genealogy and phylogeography of Cyprinid fish Labeo rohita （Hamilton, 1822） inferred from ATPase 6 and 8 mitochondrial DNA gene analysis

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Current Zoology 2014年第4期60卷 460-471页

作者： Rupesh k. LUHARIYA k.ldeep k. LAL Rajeev k. SINGH Vindhya MOHINDRA Arti GUPTA Prachi MASIH arvind k. DWIVEDI Rak.i DAS U. k. CHAUHAN J. k. JENA National Bureau ofFish Genetic Resources (ICAR) Lucknow- 226 002 UP India School of Environmental Sciences APS University Rewa- 486 003 MP India

ATPase 6/8 gene （842 bp） of mitochondrial DNA was sequenced in Labeo rohita samples （n = 253） collected from nine rivers belonging to four river basins; Indus, Ganges, Brahmaputra and Mahanadi. Analysis revealed 44 haplotypes with high haplotype diversity （Hd） 0.694 and low nucleotide diversity （π） 0.001. The within population variation was larger （83.44%） than among population differences （16.56%）. The mean Fsv value （0.166; P 〈 0.05） for overall populations revealed moderate level of genetic structuring in the wild L. rohita populations. The haplotype network.presented a single clade for wild L. rohita population, from different rivers. Negative values for Fu＇s index （Fs）, mismatch distribution analysis indicated period of expansion in L. rohita population. The time after recent expansion was estimated for each population, between 0.042 to 0.167 mya. The pattern of Isolation by Distance （IBD） was not significant （r = -0.113, P 〈 0.287）, when all the sampling locations were compared （Mantel test）, however, when an outlier （Indus, Brahmaputra and Mahanadi） was removed from the whole population set, a clear positive correlation between pairwise Fsv and geographic distance （k.） was seen. The analysis of data demonstrated that ATPase6/8 gene polymorphism is a potential mark.r to understand genetic population structure of wild L. rohita existing in different rivers. The study identified population substructure in wild L. rohita with common ancestral origin [Current Zoology 60 （4）： 460--471, 2014].

关键词： Labeo rohita ATPase6/8 mtDNA Polymorphism Genetic Divergence India

Productivity status of traditional agrisilviculture system on northern and southern aspects in mid-hill situation of Garhwal Himalaya,India

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Journal of Forestry Research 2009年第2期20卷 137-143页

作者： arvind Bijalwan Chandra Mohan Sharma V. k. Sah College of Forestry and Environment Allahabad Agricultural Institute- Deemed University Department of Botany H.N.B. Garhwal University Department of Forest Ecology College of Forestry and Hill Agriculture G. B. Pant University of Agriculture and Technology

The productivity of traditional agrisilviculture system(agricultural crops + trees) was investigated in the northern and southern aspects of mid-hill situation in Garhwal Himalaya, Uttarak.and, India during the 2004?2006.A total of 19 tree species were studied in both northern and southern aspects, out of which 17 tree species were selected in northern aspect and 12 tree species in southern aspect for phytosociological characteristic analysis of trees in agrisilvicultural *** most dominant tree species are Grewia optiva, Celtis australis and Melia azedarach and successively grown under traditional agrisilviculture *** results show that the annual productivity of all tree species was 3 775 k.·ha-1·a-1 in northern aspect(site-N) and 3 101 k.·ha-1·a-1 in southern aspect(site-S).*** had the highest productivity in both site-N and site-S among the tree species, followed by ***, Quercus leucotrichophora and *** dominant agricultural crops were Eleusine coracana in summer cereals, Phaseolus vulgaris in summer pulses-oilseeds and Triticum aestivum in the winter season in the *** average biological productivity of agricultural crops in northern aspect was about 16% higher than that in southern aspect under traditional agrisilviculture *** sole agricultural crop productivity(without trees) in northern aspect was also higher than that in southern *** obvious difference in annual productivity of trees and agriculture crops was observed between northern aspect and southern *** overall productivity in traditional agrisilviculture system(crop + tree) was 24%(in northern aspect) and 21%(in southern aspect) higher than that in sole cropping system.

关键词： traditional agrisilviculture system sole agricultural system productivity phytosociology sole crop importance value index

Virtual reality based apps are the future of patient:Counseling

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World Journal of Clinical Cases 2025年第6期13卷 58-60页

作者： Ranjan k.Behera arvind k.Morya Parul C Gupta Arshi Singh Department of Ophthalmology MMIMSR Mullana AmbalaAmbala 133207HaryānaIndia Department of Ophthalmology All India Institute of Medical SciencesHyderabad 508126TelanganaIndia Department of Ophthalmology Post Graduate Institute of Medical Education and ResearchChandigarh 160012PunjabIndia Department of Ophthalmology Guru Nanak Eye CentreNew Delhi 110001New DelhiIndia

The use of virtual reality to educate preoperative patients has a positive impact on nurses as well as patients undergoing *** can help improve patient satisfaction and improve favorable outcomes by reducing patient anxiety and proving adequate k.owledge about the procedure and possible outcomes to the *** also reduces burden on nursing staff and *** and more diverse cohort studies will help us understand the wider application of this tool on the patient *** may be difficult to apply this tool on elderly patients with failing eyesight,multiple physical ***,there may be reduced acceptance of this modality by older nursing staff and practitioners who may prefer the traditional verbal version for *** will benefit from a combined approach of using virtual reality apps with tradition one-on-one counselling to help alleviate patient concerns and improve patient and healthcare professional satisfaction.

关键词： Nurse Patient Virtual reality Counselling Healthcare

Diagenesis,facies and palaeocurrent analysis of Upper Rewa Sandstone around Sagar,Central India

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Journal of Palaeogeography 2023年第4期12卷 546-563页

作者： Gaurav k.Singh Ashish k.Rai arvind k.Singh Department of Applied Geology Dr.Harisingh Gour VishwavidyalayaSagar 470003Madhya PradeshIndia Geological Survey of India ShillongIndia

The stratigraphic surface represented by a major contact between the Archean Bundelk.and Granite and the extensive Proterozoic Vindhyan sediments is a regional basement cover *** crystalline—sedimentary interface reflects an intense weathering of continental crust during marine *** time-transgressive sand deposition events ***,Rewa and Bhander are mainly witnessed during the entire Vindhyan ***,the Upper Rewa Sandstone comprises one of these events in the Vindhyan *** progress has been made in interpreting these sandstones as a function of entirely marine process to a combination of tidal—fluvio—eolian *** the results have so far been attained on the basis of sedimentary facies,provenance,palaeocurrent analysis,and some of petrography.A distinct differentiation between marine and fluvial components of the Upper Rewa Sandstone still remains ***,we use diagenesis as a parameter for the first time along with facies and palaeocurrent analysis to acquire a clear comprehension of marine-and fluvial-dominated *** present study spans 27 square k.lometer area covering 15 stratigraphic sections with a collection of 571directional data from the facies specific sedimentary structures,and 28 samples obtained for the thin section *** lower unit of the Upper Rewa Sandstone shows facies association typical of tidal environment,along with polymodal *** rock. are well sorted and dominantly lithified by authigenic *** development of a complex of syntaxial,passive pore fills,and grain replacive cements reflect normally pressured nature of the lower unit *** upper unit of the Upper Rewa Sandstone however,reveals a facies pattern resembling fluvial processes and unimodal palaeocurrent *** exhibit poor sorting,siliceous,and ferruginous matrix,and development of intense ***,pressure solution is a dominant mode of l

关键词： Palaeocurrent Diagenesis Facies Upper Rewa Sandstone Vindhyan Basin