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Heterogeneous Catalysis with Metal-Containing Crystalline Porous Materials:Element-and Site-Specific Insights

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CCS Chemistry 2024年第5期6卷 1110-1129页

作者： Yan Li Andrew g.walsh Peng Zhang Tianjun Zhang State Key Laboratory of New Pharmaceutical Preparations and Excipients College of Chemistry and Materials ScienceHebei UniversityBaoding 071002 department of Chemistry Dalhousie UniversityHalifaxNova Scotia B3H 4R2

Metal-containing crystalline porous materials(CPMs)are gaining popularity in heterogeneous catalysis because of their highly crystalline and porous systems,and their excellent chemical *** of the metal species and framework structure permits them to have greater activity,selectivity,and stability over other *** in-depth understanding of the complex nature of metal active sites in CPMs is essential for revealing the structure-performance relationships and directing the rational design of such *** to conventional characterization techniques,the rapid development of X-ray absorption spectroscopy(XAS)has provided element-and site-specific deep insights into the electronic and structural information of metal species in *** such,this review begins by summarizing novel XAS techniques and analysis methods in accurately obtaining such ***,the combination of XAS with other high-level characterization methods into disclosing the configuration of active sites in metalcontaining CPMs is ***,the utilization of theory-assisted XAS data analysis in examining complex metal-containing CPM catalysts is ***,advanced in-situ/operando XAS studies into revealing the working sites in metal-containing CPMs under catalytic conditions are *** conclude by outlining the future challenges and prospects of XAS measurements,data analyses,and in-situ/operando setups in advancing the study of metal-in-CPM catalysts.

关键词： X-ray absorption spectroscopy in-situ metal species crystalline porous materials heterogeneous catalysis

Exploring one material for dual applications:A red-emitting Mg_(2)geO_(4):Eu^(3+)nanophosphor for future generation energy efficient WLEds and dosimetric applications

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Journal of Rare Earths 2024年第10期42卷 1835-1845页

作者： Akshay Arjun g.P.darshan S.C.Sharma H.Nagabhushana d.V.Sunitha H.b.Premkumar department of Physics Faculty of Mathematical and Physical SciencesM.S.Ramaiah University of Applied SciencesBengaluru560054India Honorary Professor of Law and Forensic Materials Jain UniversityBengaluru560069India C.N.R.Rao Centre for Advanced Materials Tumkur UniversityTumkur572103India School of Applied Sciences(Physics) REVA UniversityBengaluru560064India

The envisaged design and developme nt of individual mate rials to excavate a broader spectrum of desired properties and offer multiple applications are highly *** this in mind,a series of forsterite-structured Mg_(2)geO_(4):Eu^(3+)(1 mol%-9 mol%)nanophosphors was synthesized via a solution combustion method using oxalyl dihydrazide as a *** X-ray diffraction patterns confirm the orthorhombic crystal system with a Puma space *** results clearly show irregularly shaped cluster-like structures with aggregation of the *** diffuse reflectance spectra,the optical energy band gap of the Mg_2geO_4:Eu^(3+)(1 mol%-9 mol%)nanophosphors was estimated and obtained to be~4.12-4.32 *** photoluminescence emission spectra exhibit intense peaks at~579,589,610,661,and 707 nm,which are due to characteristic~5d_(0)→~7F_(0),~5d_(0)→~7F_(1),~5do→~7F_(2),~5d_(0)→~7F_(3)and~5d_(0)→~7F_(4)transitions of Eu^(3+)ions,*** Commission International de L'Eclairage color coordinates are gradually tuned from pale red(0.5980,0.4012)to a pure red(0.6385,0.3611)*** glow peaks showcase excellent super-linear response at low doses ofγ-irradiations,indicating that the prepared phosphor can be used in thermoluminescent personal dosimetry which is a biological tissue *** aforementioned results demonstrate that the prepared Mg_2geO_4:Eu^(3+)(1 mol%-9 mol%)nanophosphors are considered an excellent candidate for dual applications,i.e.,red component in future generation white-light-emitting diodes(WLEds)and personal dosimetric applications.

关键词： Nanophosphors Photoluminescence Thermoluminescence dosimetry Photometric properties Rare earths

Excellent photoluminescence and electrochemical properties of Sm^(3+) doped Ca_(2)MgSi_(2)O_(7) nanophosphor:display and electrochemical sensor applications

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Journal of Rare Earths 2024年第6期42卷 1046-1055,I0002页

作者： R.b.basavaraj K.Sureshkumar d.P.Aarti M.b.Madhusudana Reddy g.Nagaraju T.Ramakrishnappa g.R.Navyashree K.R.Venkatesha babu K.S.Hemalatha department of Physics BMS Institute of Technology and ManagementBangalore560064India department of Chemistry BMS Institute of Technology and ManagementBangalore560064India department of Chemistry School of Applied SciencesREVA UniversityBangalore560064India Energy Materials ResearchLaboratory Department of ChemistrySiddaganga Institute of TechnologyTumakuru57203KarnatakaIndia School of Physical Sciences REVA UniversityBangalore560057Indi department of Physics Govt.Science CollegeBengaluru560001India department of Physics Maharani Science College for WomenMaharani Cluster UniversityBengaluru560001India

A series of orange-red light emitting Ca_(2)MgSi_(2)O_(7):Sm^(3+)nanopowders were fabricated via low-cost ecofriendly green combustion technique using Aloe vera gel as *** phase purity of the samples were confirmed by the powder X-ray diffraction(PXRd)*** single-phase tetragonal structure is observed from the PXRd results with no additional impurity *** band gap energy of the fabricated powders was estimated by diffuse reflectance spectra(dRS)and is found to be in the range of 4.01-5.98 eV.A high resolution scanning electron microscope(SEM)was used to study the morphological behaviour of the ***-like structures are observed from the SEM *** particle size was evaluated by transmission electron microscopy(TEM)and is found to be~50 *** interplanar distance is found to be 0.53 *** properties were systematically studied in *** phosphors are successfully excited at 403 nm NUV light,producing reddish-orange characteristic *** emission peaks are centered at 558(^(4)g_(5/2)→^(6)H_(5/2)),607(^(4)g_(5/2)→^(6)H_(7/2))and 645 nm(^(4)g_(5/2)→^(6)H_(9/2)),*** the observed peaks the red emanation(^(4)g_(5/2)→^(6)H_(7/2))is stronger than the orange emission(^(4)g_(5/2)→^(6)H_(5/2))in the current *** photoluminescent concentration quenching is noticed above 5 mol%Sm^(3+)ion doping *** dipole-dipole interaction resulting in cross relaxation is found to be the principal cause of concentration quenching *** color features such as Commission Internationale de I’Eclairage(CIE)and correlated color temperature(CCT)were studied in *** optimized chromaticity coordinates were estimated to be(0.6363,0.3632),which fall in the reddish-orange *** average CCT value obtained is 3362 *** average color purity is found to be~82%.Sm^(3+)incorporated Ca_(2)MgSi_(2)O_(7) samples are possible contender for single white light generation commercial candidates owing to

关键词： green combustion Photoluminescence Orange-red emission Color purity Sensors Rare earths

Study of hybrid nanofluid flow in a stationary cone-disk system with temperature-dependent fluid properties

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 677-694页

作者： A.S.JOHN b.MAHANTHESH g.LORENZINI Center for Mathematical Needs Department of MathematicsCHRIST(Deemed to be University)Karnataka 560029India School of Mathematical and Statistical Sciences The University of Texas Rio Grande ValleyTexas 78539U.S.A. department of Engineering and Architecture University of ParmaParma 43124Italy

Cone-disk systems find frequent use such as conical diffusers,medical devices,various rheometric,and viscosimetry *** this study,we investigate the three-dimensional flow of a water-based Ag-Mg O hybrid nanofluid in a static cone-disk system while considering temperature-dependent fluid *** the variable fluid properties affect the dynamics and heat transfer features is studied by Reynolds's linearized model for variable viscosity and Chiam's model for variable thermal *** single-phase nanofluid model is utilized to describe convective heat transfer in hybrid nanofluids,incorporating the experimental *** model is developed as a coupled system of convective-diffusion equations,encompassing the conservation of momentum and the conservation of thermal energy,in conjunction with an incompressibility condition.A self-similar model is developed by the Lie-group scaling transformations,and the subsequent self-similar equations are then solved *** influence of variable fluid parameters on both swirling and non-swirling flow cases is ***,the Nusselt number for the disk surface is *** is found that an increase in the temperature-dependent viscosity parameter enhances heat transfer characteristics in the static cone-disk system,while the thermal conductivity parameter has the opposite effect.

关键词： hybrid nanofluid cone-disk system laminar flow variable fluid property Nusselt number

Optimal Control of Service Rates of discrete-Time(s,Q)Queueing-Inventory Systems with Finite buffer

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Journal of Systems Science and Systems Engineering 2024年第3期33卷 261-280页

作者： L.Iniya b.Sivakumar g.Arivarignan School of Mathematics Madurai Kamaraj UniversityMaduraiTamilnaduIndia department of Statistics Manonmaniam Sundaranar UniversityTirunelveliTamilnaduIndia

This article,we develop an optimal policy to control the service rate of a discrete time queueing-inventory system with finite *** customers arrive according to a bernoulli process and the service time for the customers are *** the buffer size attains its maximum,any arriving new customers are considered to be *** customers are served one by one according to FCFS rule and each customers request random number of *** inventory is replenished according to a(s,Q)inventory policy with geometric lead *** main objectives of this article are to determine the service rates to be employed at each slot so that the long run expected cost rate is minimized for fixed inventory level and fixed buffer size and to minimize the expected waiting time for a fixed inventory level and fixed buffer *** problems are modelled as Markov decision *** establish the existence of a stationary policy and employ linear programming method to find the optimal service *** provide some numerical examples to illustrate the behaviour of the model.

关键词： Queueing-inventory system discrete time batch demand-Markov decision process

The great catastrophe: causes of the Permo-Triassic marine mass extinction

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National Science Review 2024年第1期11卷 37-50页

作者： Paul b.Wignall david P.g.bond School of Earth & Environment University of Leeds School of Environmental Sciences University of Hull

The marine losses during the Permo-Triassic mass extinction were the worst ever experienced. All groups were badly affected, especially amongst the benthos(e.g. brachiopods, corals, bryozoans, foraminifers,ostracods). Planktonic populations underwent a fundamental change with eukaryotic algae being replaced by nitrogen-fixing bacteria, green-sulphur bacteria, sulphate-reducing bacteria and prasinophytes. detailed studies of boundary sections, especially those in South China, have resolved the crisis to a ～55 kyr interval straddling the Permo-Triassic boundary. Many of the losses occur at the beginning and end of this interval painting a picture of a two-phase extinction. Improved knowledge of the extinction has been supported by numerous geochemical studies that allow diverse proposed extinction mechanisms to be studied. A transition from oxygenated to anoxic-euxinic conditions is seen in most sections globally, although the intensity and timing shows regional variability. decreased ocean ventilation coincides with rapidly rising temperatures and many extinction scenarios attribute the losses to both anoxia and high *** kill mechanisms include ocean acidification for which there is conflicting support from geochemical proxies and, even less likely, siltation(burial under a massive influx of terrigenous sediment) which lacks substantive sedimentological evidence. The ultimate driver of the catastrophic changes at the end of the Permian was likely Siberian Trap eruptions and their associated carbon dioxide emissions with consequences such as warming, ocean stagnation and acidification. Volcanic winter episodes stemming from Siberian volcanism have also been linked to the crisis, but the short-term nature of these episodes(decades) and the overwhelming evidence for rapid warming during the crisis makes this an unlikely cause. Finally, whilst the extinction is well studied in equatorial latitudes, a different history is found in northern boreal latitudes

关键词： ocean anoxia ocean acidification siltation productivity collapse volcanic winter

Effect of Al_(2)O_(3)on the Mechanical Properties of(b_(4)C+Al_(2)O_(3))/Al Neutron Absorbing Materials

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1411-1420页

作者： J.X.Cai b.M.Shi N.Li Y.Liu Z.g.Zhang Y.N.Zan Q.Z.Wang b.L.Xiao Z.Y.Ma Shi‑Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Nuclear Equipment division Beijing Institute of Nuclear EngineeringChina Nuclear Power Engineering Co.Ltd.Beijing 100840China department of Materials Science School of Mechanical EngineeringShenyang UniversityShenyang 110044China

b_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear *** order to improve the high-temperature mechanical properties of b_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder *** this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(b_(4)C+Al_(2)O_(3))/Al *** was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high *** the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased *** finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional b_(4)C/Al composites.

关键词： Al matrix composites Neutron absorbing materials (b_(4)C+Al_(2)O_(3))/Al composites High-temperature strength

Assessing the biennial conference on science and technology(bICOST IX)2023 technical output on renewable energy,energy storage,and green hydrogen in line with UN Sdg commitments

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Clean Energy 2024年第2期8卷 85-88页

作者： S.K.b.d.Silva K.g.d.Piyumali Rasitha Thilini Suranjana Perera K.d.K.g.Kaluarachchi Thilini Munagamage R.M.R.Ahammed C.S.P.Piyankarage Seyed Shahmy Veranja Karunaratne National Science and Technology Commission of Sri Lanka ColomboSri Lanka Sri Lanka Technological Campus(SLTC) PadukkaSri Lanka University of Peradeniya PeradeniyaSri Lanka

The development,production and utilization of renewable energy,energy storage and green hydrogen and the associated technologies in Sri Lanka have great potential to contribute to the United Nations’Sustainable development goals(Sdgs).The island aims to achieve 70%electricity generation from renewable energy sources by 2030(within the target of 40%utilization of renewable energy sources for the entire energy generation of the country by 2030).The power sector has to invest US$11 billion from 2023 to 2030 to contribute to reaching this *** commentary aims to provide a critical perspective on the recommendations of the report from the National Science and Technology Commission’s 9th biennial conference in 2023 on science and technology,the sub-thematic technical report on clean energy,energy storage and green hydrogen in line with the Sdgs in the Sri Lankan *** technical report provides insightful recommendations for Sri Lanka’s energy sector under three main sections:renewable energy,energy storage and green ***,it explores the potential of various renewable energy sources,energy storage systems and green hydrogen as sustainable solutions to address the country’s energy challenges while emphasizing the spillover effects of them,which could contribute to the enterprise’s job creation and uplift the economy.

关键词： renewable energy energy storage green hydrogen sustainable development goals Sri Lanka social economic environmental sustainable affordable

Atomistic Investigation of Shock-Induced Amorphization within Micro-shear bands in Hexagonal Close-Packed Titanium

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Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1590-1600页

作者： Z.C.Meng K.g.Wang T.Ali d.Li C.g.bai d.S.Xu S.J.Li A.H.Feng g.J.Cao J.H.Yao Q.b.Fan H.Wang R.Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Interdisciplinary Centre for Additive Manufacturing(ICAM) School of Materials and ChemistryUniversity of Shanghai for Science and TechnologyShanghai 200093China School of Materials Science and Engineering Tongji UniversityShanghai 201804China Key Laboratory for Light-Weight Materials Nanjing Tech UniversityNanjing 210009China National Key Laboratory of Science and Technology on Materials Under Shock and Impact School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China beijing Institute of Technology Chongqing Innovation Center Chongqing 401135China

The mechanical response of a single crystal titanium sample against(0001)α surface impact was investigated using molecular dynamics ***,non-uniform plastic deformation was observed in the *** high strain rates,amorphization occurred near the edge of the contact region where severe shear strain induced a large number of stacking faults(SFs)and *** contrast,the central part of the contact region underwent less deformation with significantly fewer ***,instead of amorphization by consuming SFs and dislocations,there was a gradual increase in the density of dislocations and SFs during the process of *** local amorphous regions eventually grew into shear bands.

关键词： Shock compression Amorphization Shear band Titanium Molecular dynamics