检索结果-南通市图书馆

Geoscience Frontiers 2019年第4期10卷 1359-1370页

作者： Bulusu sreenivas sukanta Dey Y.J. Bhaskar Rao T. vijaya kumar e.v.s.s.k. babu Ian s. Williams CsIR-National Geophysical Research Institute Hyderabad 500007India Department of earth sciences Indian Institute of Science Education and ResearchKolkata 741246India Research school of earth sciences The Australian National UniversityCanberra 2601Australia

The dominant geodynamic processes that underpin the formation and evolution of earth’s early crust remain enigmatic calling for new information from less studied ancient cratonic ***,we present U-Pb ages and Hf isotopic compositions of detrital zircon grains from^2.9 Ga old quartzites and magmatic zircon from a 3.505 Ga old dacite from the Iron Ore Group of the singhbhum craton,eastern *** detrital zircon grains range in age between 3.95 Ga and 2.91 *** with the recently reported Hadean,eoarchean xenocrystic(up to 4.24 Ga)and modem detritus zircon grains from the singhbhum craton,our results suggest that the eoarchean detrital zircons represent crust generated by recycling of Hadean felsic crust formed at^4.3-4.2 Ga and^3.95 *** observe a prominent shift in Hf isotope compositions at^3.6-3.5 Ga towards super-chondritic values,which signify an increased role for depleted mantle and the relevance of plate *** Paleo-,Mesoarchean zircon Hf isotopic record in the craton indicates crust generation involving the role of both depleted and enriched mantle *** infer a short-lived suprasubduction setting around^3.6-3.5 Ga followed by mantle plume activity during the Paleo-,Mesoarchean crust formation in the singhbhum *** singhbhum craton provides an additional repository for earth’s oldest materials.

关键词： U-Pb zircon ages Hf isotopes singhbhum craton Hadean eoarchean Geodynamics

Application of Response surface Methodolody to Prediction of Dilution in Plasma Transferred Arc Hardfacing of stainless steel on Carbon steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and steel Research International 2009年第1期16卷 44-53页

作者： v Balasubramanian A k Lakshminarayanan R varahamoorthy s babu Centre for Materials Joining and Research (CeMAJOR) Department of Manufacturing EngineeringAnnamalai UniversityAnnamalai Nagar 608002Tamil NaduIndia

The application of response surface methodology was highlighted to predict and optimize the percentage of dilution of iron-based hardfaced surface produced by the PTA （plasma tratisferred arc welding） process. The experiments were conducted based on five-factor five-level central composite rotatable design with full replication technique and a mathematical model was developed using response surface methodology. Furthermore, the response surface methodology was also used to optimize the process parameters that yielded the lowest percentage of dilution.

关键词： plasma transferred arc hardfacing dilution response surface methodology

New Data on the Mineralogy of Chromite from the Nuggihalli schist Belt,Western Dharwar Craton,karnataka,India:Petrogenetic Implications

在线全文

学校读者我要写书评

暂无评论

Acta Geologica sinica(english edition) 2011年第1期85卷 107-115页

作者： Perumala v.s.RAJU elapavalooru v.s.s.k.babu Roland k.W.MeRkLe National Geophysical Research Institute Hyderabad India(Council of Scientific and Industrial Research) Department of Geology University of Pretoria PretoriaSouth Africa

The occurrence of rhythmic layering of chromite and host serpentinites in the deformed layered igneous complexes has been noticed in the Nuggihalli schist belt （NsB） in the western Dharwar craton, karnataka, south India. For this study, the chromitite rock samples were collected from Jambur, Tagadur, Bhakatarhalli, Ranganbetta and Byrapur in the NsB. Petrography and ore microscopic studies on chromite show intense cataclasis and alteration to ferritchromite. The ferritchromite compositions are characterized by higher Cr number （Cr/[Cr＋AI]）（0.68-0.98） and lower Mg number （Mg/[Mg＋Fe]）（0.33-0.82） ratios in ferritchromite compared to that of parent chromite. The formation process for the ferritchromite is thought to be related to the exchange of Mg, AI, Cr, and Fe between the chromite, surrounding silicates （serpentines, chlorites）, and fluid during serpentinization.

关键词： chromite ferritchromite Nuggihalli schist belt Dharwar Craton India

Grain to outcrop-scale frozen moments of dynamic magma mixing in the syenite magma chamber,Yelagiri Alkaline Complex,south India

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2014年第6期5卷 801-820页

作者： M.L.Renjith s.N.Charan D.v.subbarao e.v.s.s.k.babu v.B.Rajashekhar Marine and Coastal survey Division Geological Survey of IndiaCochin 682037India Geochemistry Division CSIR-National Geophysical Research InstituteHyderabad 500007India New Zealand Petroleum and Minerals Wellington 6037New Zealand

Magma mixing process is unusual in the petrogenesis of felsic rocks associated with alkaline complex worldwide. Here we present a rare example of magma mixing in syenite from the Yelagiri Alkaline Complex, south India. Yelagiri syenite is a reversely zoned massif with shoshonitic (Na2O t k2O?5e 10 wt.%, Na2O/k2O ? 0.5e2, TiO2etaluminous character. systematic modal variation of plagioclase (An11e16 Ab82e88), k-feldspar (Or27e95 Ab5e61), diopside (en34e40Fs11e18Wo46e49), biotite, and Ca-amphibole (edenite) build up three syenite facies within it and imply the role of in-situ fractional crystallization (FC). evidences such as (1) disequilibrium micro-textures in feldspars, (2) microgranular mafic enclaves (MMe) and (3) synplutonic dykes signify mixing of shoshonitic mafic magma (MgO ? 4e 5 wt.%, siO2 ? 54e59 wt.%, k2O/Na2O ? 0.4e0.9) with syenite. Molecular-scale mixing of mafic magma resulted disequilibrium growth of feldspars in syenite. Physical entity of mafic magma preserved as MMe due to high thermal-rheological contrast with syenite magma show various hybridization through chemical exchange, mechanical dilution enhanced by chaotic advection and phenocryst migration. In synplutonic dykes, disaggregation and mixing of mafic magma was confined within the conduit of injec-tion. Major-oxides mass balance test quantified that approximately 0.6 portions of mafic magma had interacted with most evolved syenite magma and generated most hybridized MMe and dyke samples. It is unique that all the rock types (syenite, MMe and synplutonic dykes) share similar shoshonitic and met-aluminous character;mineral chemistry, Ree content, coherent geochemical variation in Harker diagram suggest that mixing of magma between similar composition. Outcrop-scale features of crystal accumu-lation and flow fabrics also significant along with MMe and synplutonic dykes in syenite suggesting that Yelagiri syenite magma chamber had evolved through multiple physical processes like

关键词： Magma mixing Disequilibrium textures Petrology synplutonic dykes Geodynamics

structural evolution-enabled BiFeO3 modulated by strontium doping with enhanced dielectric,optical and superparamagnetic properties by a modified sol-gel method

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2023年第3期32卷 521-530页

作者： sharon v s veena Gopalan e Malini k A Department of Physics vimala College Thrissur-9 KeralaIndia

Multiferroic(BFO)nanoparticles doped with strontium with the general formula Bi1-xsrx FeO3(x=0,0.3,0.5,0.7)were synthesized using a modified sol-gel auto-combustion *** structural,electrical,optical,and magnetic properties of the samples are *** structural analysis,carried out using the x-ray powder diffraction technique,shows a structural transition from rhombohedral(R-3c)to cubic(Pm-3m)for the doping amount of strontium(sr)equal to x=*** analysis of the prepared samples were carried out using scanning electron microscopy(seM).Frequency-dependent dielectric constant and ac conductivity were *** doped samples,with improved dielectric properties,can be used to fabricate different optoelectronic *** dielectric dispersion and broad relaxation were exhibited by all the ***–Cole plots were employed as an effective tool to study the dispersion parameters,namely,the optical dielectric constant,static dielectric constant,relaxation time,and spreading *** activation energy was calculated from the relaxation peaks and Cole–Cole plots,which were found to be compatible with each *** bandgap of the samples was calculated using diffuse reflectance spectral(DRs)*** and strong photoluminescence in the IR region was observed in the samples,similar to ZnO,which was reported for the first ***-temperature and low-temperature magnetization studies point towards the superparamagnetic nature of the samples,with an improvement in magnetic properties with *** antiferromagnetic behavior of bulk bismuth ferrite transforms to superparamagnetic in nature for both pure and sr-substituted bismuth ferrite nanoparticles due to the close dimensions of crystallite size with magnetic domains leading to the break-down of the frustrated spin cycloidal moment.

关键词： multiferroics sol-gel process x-ray spectra optical and dielectric properties

Fluoride contamination in groundwater:A global review of the status,processes,challenges,and remedial measures

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2024年第2期15卷 1-29页

作者： e.shaji k.v.sarath M.santosh P.k.krishnaprasad B.k.Arya Manisha s.babu Department of Geology University of KeralaKariavattom CampusThiruvananthapuramKerala 695581India school of earth sciences and Resources China University of Geosciences(Beijing)29 Xueyuan RoadBeijing 100083China Department of earth science University of AdelaideAdelaideSA 5005Australia Department of Geology Central University of KeralaTejaswini HillsPeriyeKasaragodKerala 671316India

Groundwater pollution by fluoride is one of the prime concerns of the world population due to its toxicity,which results in adverse health *** this paper,we review the current scenario of the fluoride contamination of groundwater in various countries across the globe and its impact on human *** the last decade,several newly affected regions have been reported all over the world,with more than 100 countries affected by fluoride contamination in groundwater(concentration exceeding the acceptable limit of 1.5 mg/L defined by the World Health Organization).Fluoride poisoning is mainly due to the unsupervised ingestion of products for dental and oral hygiene and over-fluoridated drinking *** is estimated that more than 200 million people from different countries are affected by fluoriderelated groundwater issues and health *** highest among these are from the countries in Africa(38),Asia(28),and europe(24),followed by countries like south America(5),North America(3),and Australia(2).The source of fluoride in drinking water is primarily geogenic,together with forage,grasses and grains,tea,and anthropogenic *** countries affected were correlated with climatic zones and geological factors to gain insights into geospatial *** analyses show that most of the fluoride pollution-prone zones are located in high-grade metamorphic terranes with granitoid or alkaline intrusions,geothermal hot springs,and volcanic regions with arid or semi-arid climatic *** study also finds that children across the globe are more vulnerable than adults to fluoride *** review finds that,although there are efficient fluoride removal techniques,including filters with next-generation nanomaterials,to date,there has not been a single technique developed that can claim to be a practically robust solution for fluoride removal from drinking ***,we suggest developing next-generation filters that can retain essential miner

关键词： Fluoride Groundwater Water contamination WHO standards Climate zones Remediation sustainable Development Goals

Optimizing pulsed current gas tungsten arc welding parameters of AA6061 aluminium alloy using Hooke and Jeeves algorithm

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2008年第5期18卷 1028-1036页

作者： s.babu T.seNTHIL kUMAR v.BALAsUBRAMANIAN Centre for Materials Joining Research (CeMAJOR) Department of Manufacturing EngineeringAnnamalai UniversityAnnamalai Nagar-608 002Tamil NaduIndia Department of Automobile Technology Bharathidasan Institute of TechnologyAnna UniversityTiruchirappalli-620 016Tamil NaduIndia

Though the preferred welding process to weld aluminium alloy is frequently constant current gas tungsten arc welding (CCGTAW),it resulted in grain coarsening at the fusion zone and heat affected zone(HAZ).Hence,pulsed current gas tungsten arc welding(PCGTAW) was performed,to yield finer fusion zone grains,which leads to higher strength of AA6061 (Al-Mg-si) aluminium alloy *** order to determine the most influential control factors which will yield minimum fusion zone grain size and maximum tensile strength of the joints,the traditional Hooke and Jeeves pattern search method was *** experiments were carried out based on central composite design with 31 runs and an algorithm was developed to optimize the fusion zone grain size and the tensile strength of pulsed current gas tungsten arc welded AA6061 aluminium alloy *** results indicate that the peak current (Ip) and base current (IB) are the most significant parameters,to decide the fusion zone grain size and the tensile strength of the AA6061 aluminum alloy joints.

关键词：脉冲电流钨电极惰性气体保护焊铝合金颗粒尺寸

Petrogenesis of carbonatitic lamproitic dykes from sidhi gneissic complex,Central India

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2018年第2期9卷 531-547页

作者： M.satyanarayanan D.v.subba Rao M.L.Renjith s.P.singh e.v.s.s.k.babu M.M.korakoppa CsIR-National Geophysical Research Institute Hyderabad 500007India Geological survey of India Hyderabad 500068India Department of Geology Bundelkhand UniversityJhansi 284128India NCeGR Geological Survey of IndiaBengaluru 560070India

Petrographic, mineral chemical and whole-rock geochemical characteristics of two newly discovered lamproitic dykes(Dyke 1 and Dyke 2) from the sidhi Gneissic Complex(sGC), Central India are presented here. Both these dykes have almost similar sequence of mineral-textural patterns indicative of:(1) an early cumulate forming event in a deeper magma chamber where megacrystic/large size phenocrysts of phlogopites have crystallized along with subordinate amount of olivine and clinopyroxene;(2) crystallization at shallow crustal levels promoted fine-grained phlogopite, k-feldspar, calcite and Fe-Ti oxides in the groundmass;(3) dyke emplacement related quench texture(plumose k-feldspar, acicular phlogopites) and finally(4) post emplacement autometasomatism by hydrothermal fluids which percolated as micro-veins and altered the mafic phases. Phlogopite phenocrysts often display resorption textures together with growth zoning indicating that during their crystallization equilibrium at the crystal-melt interface fluctuated multiple times probably due to incremental addition or chaotic dynamic self mixing of the lamproitic magma. Carbonate aggregates as late stage melt segregation are common in both these dykes, however their micro-xenolithic forms suggest that assimilation with a plutonic carbonatite body also played a key role in enhancing the carbonatitic nature of these dykes. Geochemically both dykes are ultrapotassic(k_2 O/Na_2 O: 3.0-9.4) with low CaO, Al_2 O_3 and Na_2 O content and high siO_2(53.3-55.6 wt.%)and k_2 O/Al_2 O_3 ratio(0.51-0.89) characterizing them as high-silica lamproites. Inspite of these similarities, many other features indicate that both these dykes have evolved independently from two distinct magmas. In dyke 1, phlogopite composition has evolved towards the minette trend(Al-enrichment) from a differentiated parental magma having low MgO, Ni and Cr content; whereas in dyke 2, phlogopite composition shows an evolutionary affinity towards the lamproit

关键词： Lamproite Phlogopite Carbonate aggregates Metasomatized mantle sidhi Gneissic Complex Central India

Fluid-driven Hydrovolcanic Activity along Fracture Zones and near seamounts:evidence from Deep-sea Fe-rich spherules,Central Indian Ocean Basin

在线全文

学校读者我要写书评

暂无评论

Acta Geologica sinica(english edition) 2021年第5期95卷 1591-1603页

作者： Ankeeta AMONkAR sridhar D.IYeR elapavalooru v.s.s.k.babu Natarajan sHAILAJHA Areef sARDAR s.MANJU CsIR-National Institute of Oceanography Dona PaulaGoa 403004India Marine science School of EarthOcean and Atmospheric SciencesGoa UniversityGoa 403206India Formerly with CsIR-National Institute of Oceanography Dona PaulaGoa 403004India CsIR-National Geophysical Research Institute HyderabadTelangana 500007India Department of earth science Pondicherry UniversityPondicherry 605014India

An insight on occurrence of Fe-rich spherules from the Central Indian Ocean Basin(CIOB)provides an understanding of their distribution at a water depth of>5,000 *** the present study,Fe-rich spherules are identified to occur in two different sediment types(i.e.,siliceous and pelagic)and tectonic settings(*** seamounts and fracture zones).These are single spheres or aggregates,of different sizes(63 to 390μm)and show textural variability(smooth/quenched,brickwork,corkscrew,interlocking and dendritic).A comparative study based on physical morphology and chemical composition suggests a common mechanism of *** association of spherules with fracture zones(FZ)and seamounts signifies that morpho-tectonic features play an important role in fluid-driven *** on the evidence and geologic conditions existing in the basin,we conclude that molten fuel-coolant interaction(MFCI)coupled with submarine hydrothermal exhalations could be an ideal mechanism for the formation of spherules and *** accretion of the spherules on the surface sediments could be a result of recent volcanic phenomena,while those occurring at different depths(280-355,and 460-475 cm-bsf)within the sediment core indicate two different *** study provides a global implication in understanding fluid-driven magmatism in a deep-sea intraplate environment.

关键词： Fe-rich spherules deep-sea sediments hydrovolcanic activity CIOB

emission colour tuning in kLnF_(4):Yb^(3+),er^(3+)/Ho^(3+)phosphor

在线全文

学校读者我要写书评

暂无评论

Journal of Rare earths 2024年第1期42卷 57-65,I0002页

作者： Janani k Gayathri e vijayatha v Ramasubramanian s Thiyagarajan P Department of science and Humanities Nehru Institute of TechnologyKaliapuramThirumalayampalayamCoimbatoreIndia Department of sciences Amrita School of Physical SciencesAmrita Vishwa VidyapeethamCoimbatoreIndia Department of Physics Anna UniversityChennaiIndia

kLnF_(4):Yb^(3+),er^(3+)/Ho^(3+)(Ln=Y,Yb,Gd)phosphors were prepared by solid-state reaction *** each of the Yb^(3+)/er^(3+)and Yb^(3+)/Ho^(3+)co-doped phosphors independently,phase confirmation and morphological examination were accomplished using the X-ray diffraction technique and scanning electron microscope analysis.X-ray photoelectron spectroscopy analysis shows the charge state and existence of lanthanides and *** luminescence emissions of green and red colour were detected for the synthesized *** changes in the upconverted emission intensities and colour output pertaining to the change of the lanthanide host matrix along with dopants were investigated for the prepared *** the upconversion luminescence,erbium-doped samples exhibit a predominance of red emission while holmium-doped samples display a prevalence of green *** rare-earth er/Ho doped kYbF4shows strong red emission compared to other ***_(4):Yb,er/Ho exhibits relatively significant green upconve rsion emissions,while Yb,er-doped kGdF_(4)host displays a 10-fold increase in green/red emission ratio with an increase in the input power of 20-780 *** photoluminescence studies and decay curve analysis were carried out using Uv light excitation for the developed phosphors.A higher lifetime of 2.2 ms was measured for the downshifting red emission in the Ho doped kYbF_(4)*** study suggests a potential for colour tunability in the upconversion and downshifting emissions through host modifications to the fluoride phosphor.

关键词： Rare earths energy transfer upconversion Downshifting Colour coordinates