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

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(g 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

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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

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Exact solutions for magnetohydrodynamic nanofluids flow and heat transfer over a permeable axisymmetric radially stretching/shrinking sheet

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Chinese physics B 2024年第2期33卷 108-114页

作者： U.S.Mahabaleshwar g.p.Vanitha L.M.pérez Emad H.Aly I.pop Department of Studies in Mathematics Davangere UniversityShivagangothriDavangereIndia Departamento de F´ısica FACIUniversidad de Tarapac´aCasilla 7DAricaChile Department of Mathematics Faculty of EducationAin Shams UniversityRoxyCairoEgypt Department of Mathematics Babes-Bolyai University400084 Cluj-NapocaRomania

We report on the magnetohydrodynamic impact on the axisymmetric flow of Al_(2)O_(3)/Cu nanoparticles suspended in H_(2)O past a stretched/shrinked *** the use of partial differential equations and the corresponding thermophysical characteristics of nanoparticles,the physical flow process is *** resultant nonlinear system of partial differential equations is converted into a system of ordinary differential equations using the suitable similarity *** transformed differential equations are solved *** of the magnetic parameter,solid volume fraction and stretching/shrinking parameter on momentum and temperature distribution have been analyzed and interpreted *** skin friction and Nusselt number were also *** addition,existence of dual solution was deduced for the shrinking sheet and unique solution for the stretching ***,Al_(2)O_(3)/H_(2)O nanofluid flow has better thermal conductivity on comparing with Cu/H_(2)O ***,it was found that the first solutions of the stream are stable and physically realizable,whereas those of the second ones are unstable.

关键词： magnetohydrodynamic nanofluid stretching/shrinking sheet axisymmetric flow analytical solution suction/injection

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performances of fissured red sandstone after thermal treatment with constant-amplitude and low-cycle impacts

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Journal of Rock Mechanics and geotechnical Engineering 2024年第2期16卷 561-587页

作者： Yongjun Chen Tubing Yin p.g.Ranjith Xibing Li Qiang Li Dengdeng Zhuang School of Resources and Safety Engineering Central South UniversityChangsha410083China Department of Civil Engineering Monash UniversityMelbourne3800Australia Oulu Mining School University of OuluOuluFI-90014Finland

In the engineering practices,it is increasingly common to encounter fractured rocks perturbed by temperatures and frequent dynamic *** this paper,the dynamic behaviors and fracture characteristics of red sandstone considering temperatures(25℃,200℃,400℃,600℃,and 800℃)and fissure angles(0°,30°,60°,and 90°)were evaluated under constant-amplitude and low-cycle(CALC)impacts actuated by a modified split Hopkinson pressure bar(SHpB)***,fracture morphology and second-order statistics within the grey-level co-occurrence matrix(gLCM)were examined using scanning electron microscopy(SEM).Meanwhile,the deep analysis and discussion of the mechanical response were conducted through the synchronous thermal analyzer(STA)test,numerical simulations,one-dimensional stress wave theory,and material *** multiple regression models between response variables and interactive effects of independent variables were established using the response surface method(RSM).The results demonstrate the fatigue strength and life diminish as temperatures rise and increase with increasing fissure angles,while the strain rate exhibits an inverse ***,the peak stress intensification and strain rate softening observed during CALC impact exhibit greater prominence at increased fissure *** failure is dominated by tensile damage with concise evolution paths and intergranular cracks as well as the compressor-crushed zone which may affect the failure mode after 400℃.The second-order statistics of gLCM in SEM images exhibit a considerable dependence on the ***,thermal damage dominated by thermal properties controls the material structure and wave impedance and eventually affects the incident wave *** tensile wave reflected from the fissure surface is the inherent mechanism responsible for the angle effect exhibited by the fatigue strength and ***,the peak stress intensification and strain rate softening during impact are determ

关键词： Red sandstone Temperature Fissure Constant-amplitude and low-cycle(CALC) impact Fatigue failure Response surface method(RSM)

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Management of Acute Malnutrition in Children Aged 0 to 24 Months Boulbinet Health Center

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Open Journal of pediatrics 2024年第1期14卷 122-131页

作者： Mohamed Lamine Diallo Mamadou ciré Barry M’mah Aminata Bangoura Louis philippe Diffo Mamadouba Bangoura Fatoumata Sacko Telly Sy pediatric Urgencies Donka National Hospital Conakry Guinea pediatric Department Ignace Deen National Hospital Conakry Guinea Institute of Nutrition and Child Health (INSE) Conakry Guinea Boulbinet Health Center Conakry Guine gynecology-Obstetrics Department H&#244pital National Ignace Deen Conakry Guinea

Introduction: Malnutrition is a pathological state resulting from the relative deficiency or excess of one or more essential nutrients, whether manifested clinically or detected only by biochemical, anthropometric or physiological analyses. The overall objective was to assess the quality of management of acute malnutrition in children aged 0 - 24 months at the Boulbinet health center. Methodology: This was a prospective descriptive study lasting six (06) months from May 5 to October 5, 2018. The study included all children aged 0 to 24 months. Results: Acute malnutrition in children aged 0 - 24 months accounted for 2.11% of cases. The sex ratio was 1.41 in favor of males. The mean age of our patients was 5 months 7 days, with extremes of 1 month and 6 months. The majority came from Ra toma (40.24%). Exclusive breastfeeding was most common (54.02%). The main clinical signs were: pallor 49.42%, diarrhea 46.67, oral lesions37.96%. SAM represented 89.66% and MAM 10.34%. Most associated pathologies: anemia 49.42% and oral candidiasis 37.93%. In terms of outcome, we recorded 56.32% cures, 20.69% deaths, 18.39% dropouts and 4.60% cures. Conclusion: Improving the quality of care for malnourished children aged 0 - 24 months requires raising awareness among mothers and the general public of the consequences of malnutrition.

关键词： Management Acute Malnutrition Center Boulbinet

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Optimization of chemistry and process parameters for control of intermetallic formation in Mg sludges

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Journal of Magnesium and Alloys 2024年第4期12卷 1431-1448页

作者： Y.Fu g.g.Wang A.Hu Y.Li K.B.Thacker J.p.Weiler H.Hu Department of Mechanical Automotive and Materials EngineeringUniversity of Windsor401 Sunset AveWindsorOntario N9B 3P4Canada global Technology Centre Meridian Lightweight Technologies25 MacNab AveStrathroyOntario N7G 4H6Canada

Intermetallic formation in sludge during magnesium(Mg)melting,holding and high pressure die casting practices is a very important ***,very often it is overlooked by academia,original equipment manufacturers(OEM),metal ingot producers and even die *** aim of this study was to minimize the intermetallic formation in Mg sludge via the optimization of the chemistry and process *** Al8Mn5 intermetallic particles were identified by the microstructure analysis based on the Al and Mn *** design of experiment(DOE)technique,Taguchi method,was employed to minimize the intermetallic formation in the sludge of Mg alloys with various chemical compositions of Al,Mn,Fe,and different process parameters,holding temperature and holding *** sludge yield(SY)and intermetallic size(IS)was selected as two *** optimum combination of the levels in terms of minimizing the intermetallic formation were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,690℃ for the holding temperature and holding at 30 mins for the holding time,*** best combination for smallest intermetallic size were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,630℃ for the holding temperature and holding at 60 mins for the holding time,*** groups of sludge factors,Chemical Sludge(CSF),physical Sludge(pSF)and Comprehensive Sludge Factors(and CpSF)were established for prediction of sludge yields and intermetallic sizes in Al-containing Mg *** CpSF with five independent variables including both chemical elements and process parameters gave high accuracy in prediction,as the prediction of the pSF with only the two processing parameters of the melt holding temperature and time showed a relatively large deviation from the experimental *** Chemical Sludge Factor was primarily designed for small ingot producers and die casters with a limited melting and holding capacity,of which process parameters could be fixed *** physical Sludge Factor could be used f

关键词： Magnesium sludge Al-Mn intermetallic Optimization Taguchi method Sludge factor Chemical composition process parameter

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Tensile deformation of fine-grained Mg at 4K,78K and 298K

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Journal of Magnesium and Alloys 2024年第6期12卷 2534-2556页

作者： M.Walag A.Kula p.Noga T.Tokarski g.Cios M.Niewczas AgH University of Krakow Faculty of Non-Ferrous MetalsKrakowPoland AgH University of Krakow Academic Centre for Materials and NanotechnologyKrakowPoland Materials Science and Engineering McMaster UniversityHamiltonCanada

The impact of grain size,ranging from 0.9μm to 9μm,on the mechanical properties of commercially pure Mg is investigated at temperatures of 4K,78K,and *** mechanisms governing plastic flow are influenced by both grain size and *** 4K and 78K,dominant deformation modes in Mg involve dislocation glide and extension twinning,regardless of grain *** interactions between basal and non-basal dislocations and dislocations with grain boundaries promote an unusually high rate of work hardening in the plastic regime,leading to premature *** yield stress follows the Hall-petch relationshipσ_(y)∼k/√d,with the slope k increasing with decreasing *** 298K,in addition to dislocation glide and twinning,grain boundary sliding(gBS)becomes significant in samples with grain sizes below 3μm,considerably enhancing the material’s *** activation provides an additional recovery mechanism for dislocations accumulating at grain boundaries,facilitating their absorption during sliding and *** ofσrelationship suggests that the basal slip is the dominant dislocation mode in Mg at *** grain size suppresses dislocation activity and twinning and increases gBS,resulting in lowerandσ*** conventional deformation modes coupled with enhanced gBS yields stress softening,breaking down the Hall-petch relationship in Mg below 3μm grain size,leading to an inverse Hall-petch *** work reports new data on the strength,ductility,work hardening and fracture behaviour,and their variations with Mg grain size across different temperature regimes.

关键词： polycrystalline Mg Mechanical properties Deformation mechanisms Work-hardening Texture evolution Cryogenic temperatures Hall-petch relationship

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The initial stages of Li_(2)O_(2) formation during oxygen reduction reaction in Li-O_(2) batteries:The significance of Li_(2)O_(2) in charge-transfer reactions within devices

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Journal of Energy Chemistry 2024年第1期88卷 223-231,I0006页

作者： Daniela M.Josepetti Bianca p.Sousa Simone A.J.Rodrigues Renato g.Freitas gustavo Doubek Advanced Energy Storage Division LABCenter for Innovation on New EnergiesSchool of Chemical EngineeringUniversity of CampinasAv Albert Einstein 50013083-852CampinasSPBrazil Institute of physics&Department of Chemistry Laboratory of Computational MaterialsFederal University of Mato Grosso78060-900CuiabáMTBrazil

Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion ***,this theoretical characteristic has not yet been converted into a real device with high *** with air contamination,metallic lithium reactivity,and complex discharge and charge reactions are the main issues for this technology.A fast and reversible oxygen reduction reaction(ORR)is crucial for good performance of secondary batteries',but the partial knowledge of its mechanisms,especially when devices are concerned,hinders further *** this perspective,the present work uses operando Raman experiments and electrochemical impedance spectroscopy(EIS)to assess the first stages of the discharge processes in porous carbon electrodes,following their changes cycle by cycle at initial operation.A growth kinetic formation of the discharge product signal(Li_(2)O_(2))was observed with operando Raman,indicating a first-order reaction and enabling an analysis by a microkinetic *** solution mechanism in the evaluated system was ascribed for an equivalent circuit with three time *** the time constant for the anode interface reveals to remain relatively constant after the first discharge,its surface seemed to be more *** model indicated that the reaction occurs at the Li_(2)O_(2) surface,decreasing the associated resistance during the initial discharge ***,the growth of Li_(2)O_(2) forms a hetero-phase between Li_(2)O_(2)/electrolyte,while creating a more compact and homogeneous on the Li_(2)O_(2)/cathode *** methodology here described thus offers a way of directly probing changes in surface chemistry evolution during cycling from a device through EIS analysis.

关键词： Li-O_(2)battery Operando Raman analysis Equivalent circuit modeling Time-constant distribution

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Radioisotope production using lasers:From basic science to applications

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Matter and Radiation at Extremes 2024年第3期9卷 31-44页

作者： M.R.D.Rodrigues A.Bonasera M.Scisciò J.A.pérez-Hernández M.Ehret F.Filippi p.L.Andreoli M.Huault H.Larreur D.Singappuli D.Molloy D.Raffestin M.Alonzo g.g.Rapisarda D.Lattuada g.L.guardo C.Verona Fe.Consoli g.petringa A.McNamee M.La Cognata S.palmerini T.Carriere M.Cipriani g.Di giorgio g.Cristofari R.De Angelis g.a.p.cir.one D.Margarone L.giuffrida D.Batani p.Nicolai K.Batani R.Lera L.Volpe D.giulietti S.Agarwal M.Krupka S.Singh Fa.Consoli Cyclotron Institute Texas A&M UniversityCollege StationTexas 77840USA Laboratori Nazionali del Sud Istituto Nazionale di Fisica Nucleare(LNS-INFN)CataniaItaly ENEA Fusion and Technologies for Nuclear Safety and Security Department-CFrascatiItaly Centro de Láseres pulsados(clpu) VillamayorSpain Universidad de Salamanca SalamancaSpain Centre Lasers Intenses et Applications(CELIA) Universitéde BordeauxCNRSCEATalenceFrance HB11 Energy Holdings pty FreshwaterNew South WalesAustralia School of Mathematics and physics Queen’s University BelfastBelfastUnited Kingdom Dipartimento di Fisica e Astronomia“E.Majorana ”Università di CataniaCataniaItaly Facoltàdi Ingegneria e Architettura Universitàdegli Studi di Enna“Kore”EnnaItaly Dipartimento di Ingegneria Industriale Universitàdi Roma“Tor Vergata”RomaItaly Dipartimento di Fisica e geologia Universitàdegli Studi di PerugiaPerugiaItaly Istituto Nazionale di Fisica Nucleare Sezione di PerugiaPerugiaItaly ELI Beamlines Facility the Extreme Light Infrastructure ERICDolni BrezanyCzech Republic ETSIA Universidad Politécnica de MadridMadridSpain Dipartimento Fisica “E.Fermi”Universitàdi Pisa and INFNPisaItaly FZU–Institute of physics of Czech Academy of Sciences PragueCzech Republic Institute of plasma physics of Czech Academy of Sciences PragueCzech Republic

The discovery of chirped pulse amplification has led to great improvements in laser technology,enabling energetic laser beams to be compressed to pulse durations of tens of femtoseconds and focused to a few *** with energies of tens of MeV can be accelerated using,for instance,target normal sheath acceleration and focused on secondary *** such conditions,nuclear reactions can occur,with the production of radioisotopes suitable for medical *** use of high-repetition lasers to produce such isotopes is competitive with conventional methods mostly based on *** this paper,we study the production of^(67)Cu,^(63)Zn,^(18)F,and^(11)C,which are currently used in positron emission tomography and other *** the same time,we study the reactions^(10)B(p,α)^(7)Be and^(70)Zn(p,4n)^(67)ga to put further constraints on the proton distributions at different angles,as well as the reaction^(11)B(p,α)^(8)Be relevant for energy *** experiment was performed at the 1 pW laser facility at VegaⅢin Salamanca,*** distributions of radioisotopes in the forward(with respect to the laser direction)and backward directions were measured using a high purity germanium *** results are in reasonable agreement with numerical estimates obtained following the approach of Kimura and Bonasera[*** ***.,Sect.A 637,164–170(2011)].

关键词： purity estimates backward

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Challenges and opportunities in the production of magnesium parts by directed energy deposition processes

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Journal of Magnesium and Alloys 2024年第5期12卷 1663-1686页

作者： gürel Cama Ali günen Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Mechanical Engineering31200˙Iskenderun-HatayTurkey Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Metallurgy and Materials Engineering31200 Iskenderun-HatayTurkey

Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aerospace,automotive,and other transport ***,their widespread application is hindered by their low formability at room temperature due to limited slip *** Mg-alloys have low mechanical properties due to the presence of casting defects such as porosity and anisotropy in addition to the high *** casting methods benefit from established process optimization techniques for these problems,additive manufacturing methods are increasingly replacing casting methods in Mg alloys as they provide more precise control over the microstructure and allow specific grain orientations,potentially enabling easier optimization of anisotropy properties in certain *** metal additive manufacturing(MAM)technology also results in some manufacturing defects such as inhomogeneous microstructural evolution and porosity and additively manufactured Mg alloy parts exhibit lower properties than the wrought parts,they in general exhibit superior properties than the cast ***,MAM is a promising technique to produce Mg alloy *** energy deposition processes,particularly wire arc directed energy deposition(WA-DED),have emerged as an advantageous additive manufacturing(AM)technique for metallic materials including magnesium alloys,offering advantages such as high deposition rates,improved material efficiency,and reduced production costs compared to subtractive ***,the inherent challenges associated with magnesium,such as its high reactivity and susceptibility to oxidation,pose unique hurdles in the application of this *** review paper delves into the progress made in the application of DED technology to Mg-alloys,its challenges,and ***,the predominant imperfections,notably inhomo

关键词： Additive manufacturing DED processes Arc-DED Wire arc additive manufacturing(WAAM) 3-D printing High deposition rate

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