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Acta Geologica Sinica(English Edition) 2014年第1期88卷 213-225页

作者： Durbar RAY Dalayya KOTA Pranab das L.Surya Prakash v.D.KHEDEKAR Anil L.PAROPKARI Abhay v.MUDHOLKAR CSIR-National Institute of Oceanography Indian School of Mines

An extinct hydrothermal barite-silica chimney from the Franklin Seamount of the Woodlark Basin, in the southwestern Pacific Ocean, was investigated for mineral distribution and geochemical composition. Six layers on either side of the orifice of a chimney show significant disparity in color, mineral assemblage and major element composition. Electron microscope（SEM） images reveal that the peripheral wall of the chimney is composed of colloform silica, suggesting that incipient precipitation of silica-saturated hydrothermal fluid initiated the development of the chimney wall. Intermediate layers, between the exterior wall and the inner fluid-orifice, dominate with barite and sulfides. Low Sr-to-Ba ratios（SrO/BaO = 0.015–0.017） indicate restricted fluid-seawater mixing, which causes relatively high-temperature formation of the intermediate layers. Whereas the innermost layer bordering the chimney orifice is characterized by more silica and a higher Sr-to-Ba ratio（SrO/BaO = 0.023）, could have formed due to a paragenetic shift from a high-temperature active phase to a cooler waning stage of formation. A paragenetic shift is also probably responsible for the change in mineral formation mechanism that resulted in the textural variation of barite and colloform silica developed during different growth phases of this barite-silica chimney.

关键词： mineralogy oceanography geochemistry Franklin seamount barite-silica chimney

Multifunctional applications of gadolinium-doped cerium oxide(Ce_(1-x)Gd_(x)O_(2-■))ceramics:A review

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Journal of Rare Earths 2024年第10期42卷 1817-1834页

作者： Subhadip das Rakesh Bhaskar Kannan Badri Narayanan Department of Ceramic Engineering National Institute of Technology RourkelaOdisha769008India School of Chemical Engineering Yeungnam University280 Daehak-Ro Gyeongsan Gyngbuk38541Republic of Korea

Cerium oxide(CeO_(2)),or ceria,and its doped derivatives have been extensively studied for several decades and are well-known oxides valued for their unique structural properties and wide range of *** materials play a crucial role in sustainable development within *** modification through de fect e ngineering of the highly stable cubic fluorite phase enhances the versatility of this doped ceria to a new *** the numerous dopants of the CeO_(2)matrix,ceria doped with gadolinium(Gd),known as Ce_(1-x)Gd_(x)O_(2-■)(CGO),is gaining popularity due to its *** introduction of defect-induced vacancies in the oxygen sublattice(v_(o))and a change in the average valence of cerium(Ce^(3+)/Ce^(4+))are primarily responsible for the improved performance compared to pristine CeO_(2).These materials are currently undergoing intensive research for potential use as electrolytes in intermediate-temperature solid oxide fuel cells(IT-SOFCs)and dense oxygen-permeable membranes(OPMs).Additionally,they are being commercially utilized for power generation and oxygen *** materials are also attracting significant attention in various fields such as optics,photocatalysis,electrostriction,spintronics,gas sensing,electrocatalysis,and biomedical *** review paper aims to compile the latest contributions to CGO materials and comprehensively cover their various application *** crystal structure,defect equilibrium in Gd^(3+)-doped CeO_(2),the origin of multifunctionality,and the prospects of these materials are also exclusively discussed.

关键词： Gadolinium-doped CeO_(2) Rare earths Photo/electrocatalysts Gas sensors Spintronics Biomedicine

Identification of parameter to assess cracking resistance of asphalt mixtures subjected to aging and moisture conditioning

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第2期9卷 293-304页

作者： Bhaskar Pratim das Anjan Kumar Siddagangaiah Department of Civil Engineering Indian Institute of Technology GuwahatiGuiuahati 781039India

This study comprehensively evaluated different parameters based on tensile strength testing to assess the cracking resistance of asphalt mixtures subjected to aging and moisture *** this purpose,two sources of aggregates were selected to produce hot and warm mix asphalt *** mixtures were subjected to short term and long term aging,three levels of moisture conditioning(freeze thaw cycles),and tested at two temperatures(15℃and 25℃).The load-displacement data was used to determine the fracture work density,fracture energy,toughness index,cracking resistance index,cracking tolerance index,and rate dependent cracking *** was noticed that moisture conditioning increased the variability of the different *** cracking tolerance index and rate dependent cracking index parameter had a much higher coefficient of variation(Co v)with a maximum value close to 50%.Indirect tensile strength,fracture energy,and fracture work density appropriately captured the effect of moisture on cracking resistance of *** cracking resistance index,cracking tolerance index,and rate dependent cracking index increased with an increase in the moisture conditioning *** Statistical analysis showed that tensile strength,fracture work density,and fracture energy were significantly influenced by different aging and moisture conditions *** energy showed better association with fatigue life of asphalt mixtures subjected to three freeze-thaw cycles compared to tensile ***,the fatigue life prediction models showed that both indirect tensile strength and fracture energy significantly influence the fatigue life of asphalt mixtures subjected to aging and moisture conditioning.

关键词： Cracking resistance Aging Moisture Warm mix additive Fatigue life

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A HWRF-POM-TC coupled model forecast performance over North Indian Ocean: vSCS TITLI & vSCS LUBAN

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Tropical Cyclone Research and Review 2021年第1期10卷 54-70页

作者： Akhil Srivastava v.S.Prasad Ananda Kumar das Arun Sharma India Meteorological Department Ministry of Earth SciencesGovernment of IndiaNew-DelhiIndia National Center for Medium Range Weather Forecasting Ministry of Earth SciencesGovernment of IndiaUttar PradeshIndia

The HWRF-POM-TC coupled model is run operationally at India Meteorological Department(IMD).This study is first attempt to assess the IMD’s operational HWRF-POM-TC(Atmosphere-Ocean)coupled model forecast performance over North Indian Ocean(NIO).The two cyclonic storms one each in Arabian Sea and Bay of Bengal were *** them,vSCS LUBAN formed over Arabian Sea(AS)and was followed by the formation of vSCS TITLI over Bay of Bengal(Bo B).It constituted a rare case whereby two vSCS have formed in the north Indian Ocean(NIO)*** HWRF-POM-TC modeling system,which was developed at National Centers for Environmental Prediction(NCEP)based on Nonhydrostatic Mesoscale Model(NMM)dynamic core,was customized for NIO *** the two storms,vSCS LUBAN&vSCS TITLI,28 and 15 consecutive 6-hourly HWRF model runs were *** HWRF-POM-TC coupled model showed great skill in forecasting of Track and Intensity for examined *** result shows that the model predicted the intensification and landfall of vSCS Luban&Titli in agreement with the best track data as made available by Cyclone Warning Division(CWD),India Meteorological Department which is also recognized as Regional Specialized Meteorological Center(RSMC)by WMO for NIO.

关键词： Ocean coupled hurricane WRF POM-TC HWRF-POM-TC

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

Revealing the nature of optical activity in carbon dots produced from different chiral precursor molecules

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Light(Science & Applications) 2022年第5期11卷 855-867页

作者： Ananya das Evgeny v.Kundelev Anna A.vedernikova Sergei A.Cherevkov Denis v.Danilov Aleksandra v.Koroleva Evgeniy v.Zhizhin Anton N.Tsypkin Aleksandr P.Litvin Alexander v.Baranov Anatoly v.Fedorov Elena v.Ushakova Andrey L.Rogach Center of Information Optical Technologies ITMO UniversitySaint Petersburg 197101Russia Research Park Saint Petersburg State UniversitySaint Petersburg 199034Russia Laboratory of Femtosecond Optics and Femtotechnology ITMO UniversitySaint Petersburg 197101Russia Laboratory of Quantum Processes and Measurements ITMO UniversitySaint Petersburg 197101Russia Department of Materials Science and Engineering and Centre for Functional Photonics(CFP)City University of Hong KongKowloonHong Kong SAR 999077China Shenzhen Research Institute City University of Hong KongShenzhen 518057China

Carbon dots(CDs)are light-emitting nanoparticles that show great promise for applications in biology and medicine due to the ease of fabrication,biocompatibility,and attractive optical *** chirality,on the other hand,is an intrinsic feature inherent in many objects in nature,and it can play an important role in the formation of artificial complexes based on CDs that are implemented for enantiomer recognition,site-specific bonding,*** employed a one-step hydrothermal synthesis to produce chiral CDs from the commonly used precursors citric acid and ethylenediamine together with a set of different chiral precursors,namely,L-isomers of cysteine,glutathione,phenylglycine,and *** resulting CDs consisted of O,N-doped(and also S-doped,in some cases)carbonized cores with surfaces rich in amide and hydroxyl groups;they exhibited high photoluminescence quantum yields reaching 57%,chiral optical signals in the Uv and visible spectral regions,and two-photon *** signals of CDs were rather complex and originated from a combination of the chiral precursors attached to the CD surface,hybridization of lower-energy levels of chiral chromophores formed within CDs,and intrinsic chirality of the CD *** DFT analysis,we showed how incorporation of the chiral precursors at the optical centers induced a strong response in their circular dichroism *** optical characteristics of these CDs,which can easily be dispersed in solvents of different polarities,remained stable during pH changes in the environment and after Uv exposure for more than 400 min,which opens a wide range of bio-applications.

关键词： properties chiral carbon

Sb_(2)Te_(3)/graphite nanocomposite: A comprehensive study of thermal conductivity

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Journal of Materiomics 2021年第3期7卷 545-555页

作者： Subarna das P.Singha v.A.Kulbachinskii v.G.Kytin Gangadhar das S.Janaky A.K.Deb Sudip Mukherjee A.Maignan S.Hebert R.Daou Chandrabhas Narayana S.Bandyopadhyay Aritra Banerjee Department of Physics University of Calcutta92 A P C RoadKolkata700009India Laboratoire de Cristallographie et Sciences des Materiaux(CRISMAT) Normandie UniversiteUMR6508 CNRSENSICAENUNICAEN14000CaenFrance Department of Low Temperature Physics and Superconductivity Physics FacultyM.V.Lomonosov Moscow State University119991MoscowRussia Moscow Institute of Physics and Technology 141700DolgoprudnyMoscow RegionRussia Chemistry and Physics of Materials Unit Jawaharlal Nehru Centre for Advanced Scientific ResearchJakkur P.OBangalore560064India Department of Physics Raiganj UniversityUttar DinajpurWest Bengal733134India UGC-DAE Consortium for Scientific Research Mumbai CentreR-5 ShedBARC CampusTrombayMumbai400008India Center for Research in Nanoscience and Nanotechnology University of CalcuttaJD-2Sector-IIISaltlakeKolkata700106India

Thermoelectric performance largely depends on the reduction of lattice thermal conductivity(kL).The study of the thermal conductivity(k)of a Sb_(2)Te_(3)/graphite nanocomposite system demonstrates-40%reduction in kL with graphite incorporation.A plausible explanation of intrinsic low kL observed in Sb_(2)Te_(3) based system is presented by modeling experimental specific heat(Cp)*** spectroscopy measurement combined to X-Ray diffraction data confirms the presence of graphite as separate phase in the composite *** is found that phonon scattering dominates heat transport mechanism in the nanostructured Sb_(2)Te_(3)/graphite *** reduction in kL is accomplished by intensifying scattering rate of phonons via various *** introduces effective scattering sources,i.e.,defects of different dimensionalities in synthesized nanocomposite ***,graphite mediates phonon-phonon coupling and enhances lattice anharmonicity,which causes an intrinsic scattering of phonons with all frequencies in the Sb_(2)Te_(3)/graphite nanocomposite *** density and phonon anharmonicity of the synthesized samples are estimated from in depth analysis of temperature dependent synchrotron powder diffraction and Raman spectroscopic *** value as low as 0.8 W m1 K1 at 300 K,achieved with graphite dispersion in Sb_(2)Te_(3) based composite system makes the present comprehensive study an interesting concept to be developed in thermoelectric materials.

关键词： Thermoelectric systems Thermal conductivity Phonons X-ray powder diffraction Raman spectroscopy Specific heat measurements

Distance signless Laplacian eigenvalues of graphs

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Frontiers of Mathematics in China 2019年第4期14卷 693-713页

作者： Kinkar Chandra das Huiqiu LIN Jiming GUO Department of Mathematics Sungkyunkwan University Suwon 16419 Republic of Korea Department of Mat hematics East China University of Science and Technology Shanghai 200237 China

Suppose that the vertex set of a graph G is v(G) ={v1,v2,...,vn}.The transmission Tr(vi) (or Di) of vertex vi is defined to be the sum of distances from vi to all other *** Tr(G) be the n × n diagonal matrix with its (i,i)-entry equal to TrG(vi).The distance signless Laplacian spectral radius of a connected graph G is the spectral radius of the distance signless Laplacian matrix of G,defined as L(G) =Tr(G) + D(G),where D(G) is the distance matrix of *** this paper,we give a lower bound on the distance signless Laplacian spectral radius of graphs and characterize graphs for which these bounds are best *** obtain a lower bound on the second largest distance signless Laplacian eigenvalue of ***,we present lower bounds on the spread of distance signless Laplacian matrix of graphs and trees,and characterize extremal graphs.

关键词： Graph distance signless Laplacian spectral radius second largest eigenvalue of distance signless Laplacian matrix spread

A new parametrization of dark energy equation of state leading to double exponential potential

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Research in Astronomy and Astrophysics 2018年第11期18卷 1-10页

作者： Sudipta das Abdulla Al Mamon Manisha Banerjee Department of Physics Visva-Bharati Department of Mathematics Jadavpur University

We show that a phenomenological form of energy density for the scalar field can provide the required transition from decelerated(q > 0) to accelerated expansion(q < 0) phase of the *** have used the latest type Ia sup... 详细信息

We show that a phenomenological form of energy density for the scalar field can provide the required transition from decelerated(q > 0) to accelerated expansion(q ve used the latest type Ia supernova(SNIa) and Hubble parameter datasets to constrain the model parameters. The best fit values obtained from those datasets are then applied to reconstruct ωφ(z), the equation of state parameter for the scalar field. The results show that the reconstructed forms of q(z) and ωφ(z) do not differ much from the standard ΛCDM value at the current epoch. Finally, the functional form of the relevant potential v(φ) is derived by a parametric reconstruction. The corresponding v(φ)comes out to be a double exponential potential, which has a number of cosmological ***, we have also studied the effect of this particular scalar field dark energy sector on the evolution of matter overdensities.

关键词： cosmic acceleration quintessence field dark energy density perturbation

Magnesium oxide(MgO)nanoadsorbents in wastewater treatment:A comprehensive review

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Journal of Magnesium and Alloys 2024年第5期12卷 1709-1773页

作者： H.C.S.Perera v.Gurunanthanan Anoop Singh M.M.M.G.P.G.Mantilaka G.das Sandeep Arya Department of Physics Khalifa UniversityAbu Dhabi12788United Arab Emirates Postgraduate Institute of Science University of PeradeniyaPeradeniyaSri Lanka Department of Humanities and Sciences Guru Nanak Institutions Technical CampusIbrahimpatnamHyderabad501506India Centre for Global Health Research Saveetha Medical College and HospitalsSaveetha Institute of Medical and Technical SciencesChennai602105Tamil NaduIndia Department of Physics University of JammuJammu and Kashmir180006India

Wastewater contamination by heavy metals and synthetic dyes presents a significant environmental challenge,necessitating effective and sustainable separation *** review article provides a detailed examination of magnesium oxide(MgO)nanoparticles as an innovative nanoadsorbent for wastewater treatment,with a specific focus on heavy metal and dye *** review comprehensively explores various aspects of MgO nanoparticles,including their structural characteristics and synthesis *** article delves into the morphology and crystallographic arrangement of MgO nanoparticles,offering insights into their structural *** the complexity of adsorption processes,the review identifies and analyzes parameters influencing the adsorption efficiency of MgO nanoparticles,such as temperature,pH,contact time,initial concentration,and co-existing *** interplay between these parameters and the adsorption capability of MgO nanoparticles emphasizes the importance of optimizing operational ***,the review assesses various synthesis methods for MgO nanoparticles,including sol-gel,hydrothermal,precipitation,green synthesis,solvothermal,and template-assisted *** discusses the advantages,limitations,and resulting nanoparticle characteristics of each method,enabling readers to grasp the implications of synthesis processes on adsorption *** comprehensive review consolidates current insights into the effectiveness of MgO nanoparticles as a potent nanoadsorbent for removing heavy metals and dyes from wastewater covering a wide spectrum of aspects related to MgO ***,there is a need to investigate the use of MgO in the treatment of actual wastewater or river water,in order to leverage its cost-effectiveness and high efficiency for practical water treatment applications in real-time.

关键词： MgO nanoparticles Nanoadsorbent Wastewater treatment Heavy metals Dye separation Adsorption Synthesis methods