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Geochemical systematics of the Mauranipur-Babina greenstone belt,Bundelkhand craton,central India:Insights on Neoarchean mantle plume-arc accretion and crustal evolution

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Geoscience Frontiers 2018年第3期9卷 769-788页

作者： S.P.Singh k.S.V.Subramanyam c.Manikyamba M.santosh M.Rajanikanta Singh B.chandan kumar Department of Geology Institute of Earth SciencesBundelkhand UniversityJhansiU.P284128India cSIR-National Geophysical Research Institute Uppal RoadHyderabad500007India Department of Earth Sciences University of AdelaideAustralia School of Earth Science&Resources China University of GeosciencesBeijingChina Department of Geology Central University of KeralaKasaragodKerala671316India

The Neoarchean Bundelkhand greenstone sequences at Mauranipur and Babina areas within the Bundelkhand Gneissic complex preserve a variety of magmatic rocks such as komatiitic basalts, basalts,felsic volcanic rocks and high-Mg andesites belonging to the Baragaon, Raspahari and koti *** intrusive and extrusive komatiitic basalts are characterized by low SiO_2(39-53 wt.%), high MgO(18-25 wt.%).moderately high Fe_2O_3(7.1-11.6 wt.%), Al_2O_3(4.5-12.0 wt.%), and TiO_2(0.4-1.23 wt.%)with super to subchondritic(Gd/Yb)N ratios indicating garnet control on the melts. The intrusive komatiitic suite of Ti-enriched and Al-depleted type possesses predominant negative Eu and positive Nb, Ti and Y anomalies. The chemical composition of basalts classifies them into three types with varying SiO_2, TiO_2, MgO, Fe_2O_3, Al_2O_3 and caO. At similar SiO_2 content of type Ⅰ and Ⅲ basalts, the type II basalts show slightly high Al_2O_3 and Fe_2O_3 contents. Significant negative anomalies of Nb, Zr, Hf and Ti, slightly enriched LREE with relatively flat HREE and low ∑REE contents are observed in type Ⅰ and Ⅱ basalts. TypeⅢ basalts show high Zr/Nb ratios(9.8-10.4), TiO_2(1.97-2.04 wt.%), but possess strikingly flat Zr, Hf, Y and Yb and are uncontaminated. Andesites from Agar and koti have high SiO_2(55-64 wt.%), moderate TiO_2(0.4-0.7 wt.%), slightly low Al_2O_3(7-11.9 wt.%), medium to high MgO(3-8 wt.%) and caO contents(10-17 wt.%). Anomalously high cr, co and Ni contents are observed in the koti rhyolites. Tholeiitic to calc alkaline affinity of mafic-felsic volcanic rocks and basalt-andesite dacite-rhyolite differentiation indicate a mature arc and thickened crust during the advanced stage of the evolution of Neoarchean Bundelkhand greenstone belt in a convergent tectonic setting where the melts were derived from partial melting of thick basaltic crust metamorphosed to amphibolite-eclogite facies. The trace element systematics suggest the presence of arc-back arc association w

关键词： Bundelkhand craton Greenstone belts Mantle dynamics Plume-arc accretion Neoarchean crustal evolution

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Geochemical cycling during subduction initiation:Evidence from serpentinized mantle wedge peridotite in the south Andaman ophiolite suite

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Geoscience Frontiers 2018年第6期9卷 1755-1775页

作者： Abhishek Saha M.santosh Sohini Ganguly c.Manikyamba Jyotisankar Ray Jagadish Dutta cSIR-National Institute of Oceanography Dona PaulaGoa 403 004India School of Earth Science and Resources China University of GeosciencesBeijing100083China Department of Earth Sciences University of AdelaideAdelaideSA 5005Australia Department of Earth Science Goa UniversityTaleigao PlateauGoa 403206India cSIR-National Geophysical Research Institute Uppal RoadHyderabad500 007India Department of Geology University of Calcutta35Ballygunge Circular RoadKolkata700 019India

The ophiolite suite from south Andaman Islands forms part of the Tethyan Ophiolite Belt and preserves the remnants of an ideal ophiolite sequence comprising a basal serpentinized and tectonised mantle peridotite followed by ultramafic and mafic cumulate units, basaltic dykes and spilitic pillow basalts interlayered with arkosic wacke. Here, we present new major, trace, rare earth(REE) and platinum group(PGE) element data for serpentinized and metasomatized peridotites(dunites) exposed in south Andaman representing the tectonized mantle section of the ophiolite suite. Geochemical features of the studied rocks, marked by Al_2 O_3/TiO_2 > 23, LILE-LREE enrichment, HFSE depletion, and U-shaped chondrite-normalized REE patterns with(La/Sm)N > 1 and(Gd/Yb)N contributions from boninitic mantle melts. These observations substantiate a subduction initiation process ensued by rapid slab roll-back with extension and seafloor spreading in an intraoceanic fore-arc regime. The boninitic composition of the serpentinized peridotites corroborate fluid and melt interaction with mantle manifested in terms of(i) hydration, metasomatism and serpentinization of depleted, MORB-type, sub-arc wedge mantle residual after repeated melt extraction; and(ii) refertilization of refractory mantle peridotite by boninitic melts derived at the initial stage of intraoceanic subduction. Serpentinized and metasomatized mantle dunites in this study record both MOR and intraoceanic arc signatures collectively suggesting suprasubduction zone affinity. The elevated abundances of Pd(4.4-12.2 ppb) with highΣPPGE/∑IPGE(2-3) and Pd/Ir(2-5.5) ratios are in accordance with extensive melt-rock interaction through percolation of boninitic melts enriched in fluid-fluxed LILE-LREE into the depleted mantle after multiple episodes of melt extraction. The high Pd contents with relatively lower Ir concentrations of the samples are analogous to characteristic PGE signatures of boninitic magmas and might have r

关键词： South Andaman Ophiolite Mantle peridotite Metasomatism Geochemical cycling Subduction initiation

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Effect of chemical composition on zircon radiation damage dating:Implications for low-temperature thermochronology

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Geoscience Frontiers 2023年第6期14卷 368-379页

作者： Mingpu Fan Xiaoming Liu Shengsi Sun Yunpeng Dong John c.Ayers M.santosh State key Laboratory of continental Dynamics Department of GeologyNorthwest UniversityXi’an 710069China Vanderbilt University Department of Earth&Environmental SciencesPMB 3518052301 Vanderbilt PlaceNashvilleTN 37235-1805USA School of Earth Science and Resources China University of GeosciencesBeijing 100083China Department of Earth Science University of AdelaideAdelaideSA 5005Australia Yonsei Frontier Lab Yonsei UniversitySeoul 03722Republic of Korea

Zircon radiation damage dating is a low-temperature thermochronological method that can reveal the cooling histories of magmatic intrusions and discriminate sedimentary provenance in combination with other dating *** method has broad application prospects because of its advantages of nondestructive,high efficiency,and capable of double(or multiple)dating,involving only multiple measurements by Raman spectrometer and laser ablation-inductively coupled plasma-mass ***,several factors,such as zircon chemical composition and the non-uniformity of radiation damage annealing kinetics,can cause poor precision when using this method and thus restricts its wide *** study examined the effect of chemical composition(P,Ti,Dy,Th,U,and Hf)on Raman spectra using synthetic zircon crystals grown in a lithium-molybdate *** results show that the full width at half-maximum(FWHM)of the v_(3)(SiO_(4))band has positive linear correlations with the concentrations of P,Ti,Dy,Th,and U in decreasing order of influence,while the FWHM is unaffected by Hf at concentrationscreases at concentrations>10 wt.%.Furthermore,the Raman shift is negatively correlated with Th,U,and Dy concentrations,positively correlated with Hf,and shows no obvious correlation with Ti and ***,our study shows that chemical composition is a non-ignorable factor for calculating zircon radiation damage age using Raman spectroscopy,especially for zircon with relatively high concentrations of P,rare earth elements(REEs),Th,U,and *** obtained multiple linear regression equation provides a potential means for estimating the FWHM at zero dose and implication for improving the dating precision of this *** addition,the observed effects of REEs,Th,U,and Hf on the Raman shift of the v_(3)(SiO_(4))band indicate that chemical composition in zircon might affect the estimation of the P-T conditions of geological processes when using entrapped zircon inclusions in host mi

关键词： Synthetic zircon Raman spectroscopy chemical composition Radiation damage dating cooling age

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Sapphirine granulites from Panasapattu,Eastern Ghats belt,India:Ultrahigh-temperature metamorphism in a Proterozoic convergent plate margin

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Geoscience Frontiers 2012年第1期3卷 9-31页

作者： c.V.Dharma Rao M.santosh Reia M.chmielowski National Disaster Management Authority Government of India A-1 Safdarjung EnclaveNew DelhiIndia Department of Interdisciplinary Science Faculty of Science Kochi UniversityAkebono-choKochi 780-8520Japan Dipartimento di Scienze della Terra Universita degli Studi di Milano Italy

We report equilibrium sapphirine ＋ quartz assemblage in biotite-orthopyroxene-garnet granulites from a new locality in Panasapattu of Paderu region in the Eastern Ghats granulite belt, which provide new evidence for ultrahigh-temperature （UHT） metamorphism at 1030-1050 ℃ and 10 kbar in this region. The development of migmatitic texture, stabilization of the garnet-orthopyroxene- plagioclase-k-feldspar association, prograde biotite inclusions within garnet and sapphirine as well as sapphirine and cordierite inclusions within garnet in these granulites indicate that the observed peak assemblages probably formed during prograde dehydration melting of a Bt-Sill-Qtz assemblage, and constrain the prograde stage of the p--T path. The core domains of orthopyroxene porphyroblasts have up to w（Al203） 9.6%, which suggest that the temperatures reached up to 1150 ~c suggesting extreme crustal metamorphism. These conditions were also confirmed by the garnet-orthopyroxene thermobar- ometery, which yields a p--T range of 1012--960 ~c and 9.4 kbar. The p--T phase topologies computed using isochemical sections calculated in the model system Na20-caO-k20--FeO-MgO-A1203-SiO2 --H2O （NckFMASH） for metapelites, garnet-free sapphirine granulites and garnet-bearing sapphirine granulites match the melt-bearing assemblages observed in these rocks. Isochemical sections constructed in the NckFMASH system for an average sub-aluminous metapelite bulk composition, and contoured for modal proportions of melt and garnet, as well as for the compositional isopleths of garnet, predict phase and reaction relations that are consistent with those observed in the rocks. Garnet and orthopyroxene contain Ti-rich phlogopite inclusions, suggesting formation by prograde melting reactions at the expense of phlogopite during ultrahigh-temperature conditions. These p--T results underestimate ＇peak＇ condi- tions, in part as a result of the modification of garnet compositions in the domains where some melt was retai

关键词： Panasapattu Eastern Ghats belt Melting Sapphirine + quartz Ultrahigh-temperaturemetamorphism Tectonics

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Antioxidant and antimutagenic activities of bark extract of Terminalia arjuna

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Asian Pacific Journal of Tropical Medicine 2010年第12期3卷 965-970页

作者： Gollapalle Lakshminarayana shastry Viswanatha santosh kumar Vaidya Ramesh c Nandakumar krishnadas Srinath Rangappa Department of Pharmacology PES College of PharmacyBangalore-560050 India Department of Pharmacology St.John's College of PharmacyBangalore-560040 India Department of Pharmacology Manipal College of Pharmaceutical SciencesManipal-576104 India

Objective:The alcoholic extract of stem bark of Terminalia arjuna（ALTA） was screened for antioxidant and antimutagenic（anticlastogenic） ***:Antioxidant property was determined by l,l,Diphynyl,2-Picryl hydrazyl（DPPH） assay,super oxide radical scavenging activity,lipid peroxidation assay and total polyphenolic content was determined by Folin-ciocalteau’s *** activity was evaluated using micronucleus test in mice. Results:The ALTA has shown potent antioxidant activity with Ec50 of 2.491±0.160,50.110±0.150 & 71.000±0.250 in DPPH assay,superoxide radical scavenging activity and lipid peroxidation assay, which is comparable with ascorbic acid with Ec50 of 2.471±0.140,40.500±0.390 and 63.000±0.360 *** micronucleus test,ALTA（100 & 200 mg/kg,p.o.） showed significant reduction in percentage of micronucleus in both polychromatic erythrocytes（PcE） and normochromatie erythrocytes（NcE） and also shown significant reduction in P/N ***:These results suggested that ALTA possess significant antioxidant and antimutagenic activity.

关键词： Terminalia arjuna Antioxidant activity Antimutagenic activity Micronuclease test

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Flow past a bluff body subjected to lower subcritical Reynolds number

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Journal of Ocean Engineering and Science 2020年第2期5卷 173-179页

作者： Pankaj kumar santosh kumar Singh Department of Mechanical Engineering SRM Institute of Science and TechnologyKattankulathur 603203India

The paper aimed to study the flow structure at the wake of the bluff body with altered blockage ratio(BR)keeping the fixed aspect ratio(AR).The study was conducted by a finite volume technique using commercial software *** cFD analysis of the bluff body is mainly subjected to the lower subcritical Reynolds number range(5000 to 15,000)along with blockage ratio as an important *** flow parameters such as drag coefficient,pressure,and kinetic energy variations are analyzed here for the Reynolds number(Re)and *** was observed that at fixed Re,t he drag coefficient(c_(D))increases with an increase in the BR while decrease with increasing Re for a fixed value of BR.

关键词： Blockage ratio Bluff body Drag coefficient Reynolds number

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classical model for diffusion and thermalization of heavy quarks in a hot medium: memory and out-of-equilibrium effects

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chinese Physics c 2019年第9期43卷 90-100页

作者： Marco Ruggieri Marco Frasca santosh kumar Das School of Nuclear Science and Technology Lanzhou University222 South Tianshui RoadLanzhou 730000China Via Erasmo Gattamelata Rome 00176Italy School of Physical Science Indian Institute of Technology GoaPonda-403401GoaIndia

We consider a simple model for the diffusion of heavy quarks in a hot bath,modeling the latter by an ensemble of oscillators distributed according to either a thermal distribution or to an out-of-equilibrium distribution with a saturation *** this model it is easy to introduce memory effects by changing the distribution of oscillators:we model them by introducing a Gaussian distribution,dN/dω,which can be deformed continuously from aδ?function,giving a Markov dissipation,to a broad kernel with *** the equation of motion of the heavy quark in the bath,we remark how dissipation comes out naturally as an effect of the back-reaction of the oscillators on the ***,the exact solution of this equation allows to define the thermalization time as the time necessary to remove any memory of the initial *** find that the broadening of the dissipative kernel,while keeping the coupling fixed,lowers the thermalization *** also derive the fluctuation-dissipation theorem for the bath,and use it to estimate the kinematic regime in which momentum diffusion of the heavy quark dominates over *** find that diffusion is more important as long as k0/E is small,where k0 and E denote the initial energy of the heavy quark and the average energy of the bath,respectively.

关键词： relativistic heavy ion collisions heavy quarks Brownian motion memory effect quark-gluon plasma

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The naked planet Earth:Most essential pre-requisite for the origin and evolution of life

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Geoscience Frontiers 2013年第2期4卷 141-165页

作者： S.Maruyama M.Ikoma H.Genda k.Hirose T.Yokoyama M.santosh Department of Earth and Planetary Sciences Tokyo Institute of Technology2-12-1 OokayamaMeguro-kuTokyo 152-8551Japan Department of Earth and Planetary Science.The University of Tokyo 7-3-1 HongoBunkyo-kuTokyo 113-0033.Japan Department of Earth and Planetary Sciences.Tokyo Institute of Technology 2-12-1 OokayamaMeguro-ku.Tokyo 152-8551Japan School of Earth Sciences and Resources China University of Geosciences(Beijing) Faculty of Science Kochi UniversityKochi 780-8520Japan

Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the *** we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of *** evaluate：（1） the source of nutrients,（2） the chemistry of primordial ocean,（3） the initial mass of ocean,and（4） the size of *** the life-building nutrients,phosphorus and potassium play a key *** three types of rocks can serve as an adequate source of nutrients：（a） continent-forming TTG（granite）,enabling the evolution of primitive life to metazoans;（b） primordial continents carrying anorthosite with kREEP（Potassium,Rare Earth Elements, and Phosphorus） basalts,which is a key to bear life;（c） carbonatite magma,enriched in radiogenic elements such as U and Th,which can cause mutation to speed up evolution and promote the birth of new species in continental rift *** second important factor is ocean *** primordial ocean was extremely acidic（pH = 1-2） and enriched in halogens（cI,F and others）,S,N and metallic elements（cd,cu,Zn,and others）,inhibiting the birth of *** tectonics cleaned up these elements which interfered with *** ocean finally appeared in the Phanerozoic with pH = 7 through extensive interaction with surface continental crust by weathering,erosion and transportation into *** initial ocean mass was also *** birth of life and aftermath of evolution was possible in the habitable zone with 3-5 km deep ocean which was able to supply sufficient nutrients. Without a huge landmass,nutrients cannot be supplied into the ocean only by ridge-hydrothermal circulation in the ***,the size of the planet plays a crucial *** of massive planets is less efficient than smaller ones,so that return-flow of seawater into mantle does not occur until central stars finish their main *** to the suitable size of Earth,the dawn of Phaneroz

关键词： Earth Life Habitable planet Initial ocean mass Metazoan Nutrients

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Retinal structural-vascular-functional relationship using optical coherence tomography and optical coherence tomography -angiography in myopia

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Eye and Vision 2019年第1期6卷 51-62页

作者： Ramesh Venkatesh Shivani Sinha Deepika Gangadharaiah santosh G.k.Gadde Ashwin Mohan Rohit Shetty Naresh kumar Yadav Department of Retina and Vitreous Narayana Nethralaya#121/C1st R BlockChord RoadRajaji NagarBengaluru 560010India. Department of cornea and Refractive surgery Narayana Nethralaya#121/C1st R BlockChord RoadRajaji NagarBengaluru 560010India

Background:To examine the retinal structure–vascular-function relationship using optical coherence tomography(OcT)and optical coherence tomography angiography(OcTA)in ***:This was a prospective cross-sectional study comprising 86 eyes of 45 individuals with varying axial lengths and spherical equivalents and no posterior segment *** eyes underwent optical coherence tomography with the Spectralis SD-OcT and OcTA with RTVue-XR Avanti;*** macular retinal layer thicknesses and flow areas and vessel densities were measured on OcT and OcTA,*** correlations were made between the macular layer thicknesses,flow areas and vessel densities with axial length,spherical equivalent and visual ***:The participants’mean ages were 33.34±14.45 years,mean spherical equivalent refractions were−7.17±5.71 D and axial lengths were 25.95±2.41 *** were significant positive correlations of foveal angle(r=0.757,p=0.001),inner retinal(r=0.764,p=0.001)and outer plexiform layer(r=0.771,p=0.001)thickness on OcT and vessel densities in deep capillary plexus(r=0.313,p=0.003)on OcTA with axial length and negative correlations with spherical equivalents and visual *** negative correlations of outer nuclear layer(r=−0.560,p=0.03)and photoreceptor outer segment layer thickness(r=−0.856,pcT with axial length and positive correlations with spherical equivalents and visual ***:The lateral retinal stretching in myopia could possibly explain the correlation between retinal layer thickness,vascular density and visual acuity in these *** research is required to investigate this.

关键词： Myopia Axial elongation Spherical equivalent OcT Optical coherence tomography angiography Structure Visual acuity

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YFa and analogs:Investigation of opioid receptors in smooth muscle contraction

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World Journal of Gastroenterology 2011年第40期17卷 4523-4531页

作者： krishan kumar Ritika Goyal Annu Mudgal Anita Mohan santosh Pasha Peptide Synthesis Laboratory Institute of Genomics and Integrative Biology Delhi 110007 India University School of Basic and Applied Sciences GGSIP University Sector-16 c Dwarka Delhi 110075 India Department of chemistry Motilal Nehru college University of Delhi Delhi 110021 India

AIM:To study the pharmacological profile and inhibition of smooth muscle contraction by YFa and its analogs in conjunction with their receptor selectivity. METHODS:The effects of YFa and its analogs (D-Ala2) YFa, Y (D-Ala2) GFMkkkFMRF amide and Des-Phe-YGGFMkkkFMR amide in guinea pig ileum (GPI) and mouse vas deferens (MVD) motility were studied using an isolated tissue organ bath system, and morphine and DynA (1-13) served as controls. Acetylcholine was used for muscle stimulation. The observations were validated by specific antagonist pretreatment experiments using naloxonazine, naltrindole and norbinaltor-phimine norBNI. RESULTS:YFa did not demonstrate significant inhibition of GPI muscle contraction as compared with mor-phine (15% vs 62%, P = 0.0002), but moderate inhibition of MVD muscle contraction, indicating the role of κ opioid receptors in the contraction. A moderate inhibition of GPI muscles by (Des-Phe) YFa revealed the role of anti-opiate receptors in the smooth muscle contraction. (D-Ala-2) YFa showed significant inhibition of smooth muscle contraction, indicating the involvement of mainly δ receptors in MVD contraction. These results were supported by specific antagonist pretreatment assays. cONcLUSION:YFa revealed its side-effect-free analgesic properties with regard to arrest of gastroin-testinal transit. The study provides evidences for the involvement of κ and anti-opioid receptors in smooth muscle contraction.

关键词： Opioid receptor Guinea pig ileum Mousevas deferens Smooth muscle contraction Gastrointestinal motility

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