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Geochemistry and mineralogy of beach sediments in the northern Gulf of Mexico,Tamaulipas state,Mexico:implication for provenance

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Journal of Palaeogeography 2024年第3期13卷 375-400页

作者： Mayank Shukla sanjeet k.verma Mayla A.Ramos-Vázquez John S.Armstrong-Altrin karla R.Hernández-Martínez Sumit Mishra Vivek P.Malviya Héctor Hernández-Mendoza Posgrado de la Division de Geociencias Aplicadas Instituto Potosino de Investigacion Científica y Tecnologica(IPICYT)Camino a la Presa San José2055San Luis Potosí78216Mexico Division de Geociencias Aplicadas Instituto Potosino de Investigación Científica y Tecnologica(IPICYT)Camino a la Presa San Jose 2055San Luis Potosí78216Mexico Universidad Nacional Autonoma de México Instituto de Ciencias del Mar y LimnologíaUnidad de ProcesosOceanicos y CosterosCiudad UniversitariaCiudad de México 04510Mexico Department of Marine Sciences Bharathidasan UniversityTiruchirappalli620024Tamil NaduIndia Instituto de Geociencias Universidad Nacional Autonoma de MéxicoBoulevard Juriquilla 300176230JuriquillaQueretaroMexico Department of Applied Geology Dr.Harisingh Gour Central UniversitySagar470002Madhya PradeshIndia Instituto de Investigacion de Zonas Desérticas Universidad Autònoma de San Luis PotosíAltair 200CP 78377San LuisS.L.P.Mexico Universidad del Centro de Mexico Capitán Caldera 75CP 78250San LuisS.L.P.Mexico

Geochemical and mineralogical studies were performed in the La Pesca(LP)and Tesoro Altamira(TA)beach sediments,located in the Tamaulipas state,northern Gulf of *** main aim of this study is to infer the weathering history and provenance and to discriminate the tectonic environment of the beach *** sediments are composed of quartz with small amounts of accessory minerals such as plagioclase,calcite,orthoclase,microcline,and *** beach sediments are classified as fine-grained and very well sorted,however LP has coarse skewed and leptokurtic sediments,whereas TA has fine-skewed and very leptokurtic *** chemical index of weathering(CIW’)indicates intense weathering in the source *** quartz grain microtextures in the LP and TA are classified into mechanical,chemical,and mechanical/chemical *** features such as fractures,pits,percussion marks,abrasion fatigue,and V-shaped marks favor high-energy littoral,fluvial,subaqueous-marine,and aeolian *** chemical features indicate solution pits and crystalline overgrowth,which suggests a silica saturated marine *** mechanical/chemical features display adhering particles and elongated depressions suggest formation in a sub-aqueous nearshore marine *** and trace elements-based provenance discrimination diagrams indicate a felsic source derived from the Mesa Central(MC),Sierra Madre Oriental(SMOr)and Oaxaquia *** major and trace element concentrations imply a passive margin setting for the northern Gulf of Mexico,which is consistent with the general geology.

关键词： Beach sediments Geochemistry Mineralogy Provenance Tamaulipas Tectonic setting

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Tectonic Implications of the Combined Use of Tectonomagmatic Geochemical Discrimination Diagrams and Indicators of Magma Flow Sense in Mafic Dykes

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Acta Geologica Sinica(English Edition) 2016年第S1期90卷 39-页

作者： Elson P.OLIVEIRA sanjeet k.verma Department of Geology University of Campinas División de Geociencias Aplicadas Instituto Potosino de Investigación Científica y Tecnológica

Geochemistry is a powerful tool to help characterize the tectonic setting of igneous rocks ***,when continental mafic dykes and flood basalts are the target most of the proposed geochemical discrimination diagrams fai... 详细信息

关键词： In Tectonic Implications of the Combined Use of Tectonomagmatic Geochemical Discrimination Diagrams and Indicators of Magma Flow Sense in Mafic Dykes

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Analysis of Security Vulnerabilities and Countermeasures of Ethernet Passive Optical Network(EPON)

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China Communications 2007年第3期4卷 17-29页

作者： Stamatios V.kartalopoulos Pramode k.verma School of Electrical and Computer Engineering Telecommunications Systems Program University of Oklahoma-Tulsa Tulsa Ok 74135 USA

Ethernet-based Passive Optical Network(EPON) is considered a very promising solution for the first mile problem of the next generation *** to its particular characteristic of shared media structure,EPON suffers many security vulnerabilities. Communication security must be guaranteed when EPON is applied in *** paper gives a general introduction to the EPON system,analyzes the potential threats and attacks pertaining to the EPON system,and presents effective countermea-sures against these threats and attacks with emphasis on the authentication protocols and key distribution.

关键词： EPON security vulnerabilities attacks countermeasures authentication protocols key distribution

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The tumor suppressor RASSF1A is a novel effector of small G protein Rap1A

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Protein & Cell 2011年第3期2卷 237-249页

作者： Sunil k.verma Trivadi S.Ganesan Uday kishore Peter J.Parker Department of Medical Oncology Medical Sciences DivisionThe University of OxfordOxford OX39DUUK Ovarian Cancer Group CRUK Molecular Oncology LaboratoriesWeatherall Institute of Molecular MedicineJohn Radcliffe HospitalHeadingtonOxford OX39DSUK Protein Phosphorylation Laboratory London Research InstituteCRUK Lincoln's Inn Fields Laboratories44 Lincoln's Inn FieldsLondon WC2A 3PXUK kings College London The Division of Cancer StudiesSection of Cancer Cell Biology and Imaging2nd FloorNew Hunt's HouseGuy's HospitalSt Thomas StreetLondon SE11ULUK Current address:Center for Cellular and Molecular Biology Uppal RoadHyderabad 500007India Current address:Cancer Institute&Institute of Molecular Medicine Amrita Institute of Medical SciencesElamakkara P.O.KochiKerala 682026India Center for Infection Immunity and Disease MechanismsBiosciencesSchool of Health Sciences and Social CareBrunel UniversityUxbridge UB83PHWest LondonUK

Rap1A is a small G protein implicated in a spectrum of biological processes such as cell proliferation,adhesion,differentiation,and *** downstream effectors through which Rap1A mediates its diverse effects are largely *** we show that Rap1A,but not the related small G proteins Rap2 or Ras,binds the tumor suppressor Ras association domain family 1A(RASSF1A)in a manner that is regulated by phosphorylation of *** with Rap1A is shown to influence the effect of RASSF1A on microtubule behavior.

关键词： RASSF1A Rap1A microtubule vimentin protein-protein interaction

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Bianchi-Type VI_(0) Bulk Viscous Fluid Models with Variable Gravitational and Cosmological Constants

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Applied Mathematics 2011年第3期2卷 348-354页

作者： Manoj k.verma Shri Ram Department of Applied Mathematics Institute of TechnologyBanaras Hindu UniversityVaranasiIndia

This paper deals with Bianchi type VI0 anisotropic cosmological models filled with a bulk viscous cosmic fluid in the presence of time-varying gravitational and cosmological constant. Physically realistic solutions of Einstein's field equations are obtained by assuming the conditions 1) the expansion scalar is proportional to shear scalar 2) the coefficient of the bulk viscosity is a power function of the energy density and 3) the cosmic fluid obeys the barotropic equation of state. We observe that the corresponding models retain the well established features of the standard cosmology and in addition, are in accordance with recent type Ia supernovae observations. Physical behaviours of the cosmological models are also discussed.

关键词： Bianchi VI0 Cosmology Bulk viscosity Variable G and A

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A Network Based Authentication Scheme for VoIP

A Network Based Authentication Scheme for VoIP

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2006 10th International Conference on Communication Technology（ICCT 2006）

作者： Pramode k.verma School of Electrical and Computer Engineering University of OklahomaTulsa OK USA

This paper presents a VoIP networking solution that incorporates network-based authentication as an inherent feature. The authentication feature that we propose introduces a range of flexibilities not available in the PSTN. Since most calls will likely terminate on the network of another service provider, we also present a mechanism using which networks can mutually authenticate each other to afford the possibility of authentication across networks.

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Preparation by chemical co-precipitation, spectral and electrical characteristics of neodymium orthophosphate nanoparticles

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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

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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

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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

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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)

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