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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(rwhelming 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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Soil security and global food security

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Frontiers of Agricultural Science and Engineering 2024年第2期11卷 297-302页

作者： david r.MONTGOMErY Department of Earth and Space Sciences University of Washington townSeattleWA 98105USA

Over the course of the postglacial period has managed to add degrade a substantial portion of the world's potential agricultural land. The soil loss and degradation that has repeatedly impacted regional societies around the world resulted from agricultural practices that increased the physical loss of soil(erosion), reduced soil organic matter, changed p H(acidification) or salinity,and disrupted or altered communities of soil life. In the coming century, as continued soil degradation threatens global food security while the global population keeps rising it is imperative that farmers develop and adopt soilhealth building(regenerative) practices to solve a problem that has plagued societies throughout history. Growing evidence suggests that agricultural systems that combine cover crops, reduced tillage, and diverse crop rotations can reduce erosion, enhance soil health and rebuild soil organic matter to cultivate beneficial soil life and harvest both economic and environmental benefits. In the coming post-oil world, global food security would benefit from a global effort to promote soil restoration to help addresses the challenge of sustainably feeding the world, increase soil-based carbon sequestration,protect on-farm biodiversity and reduce off-farm water pollution. because soil security sets a solid foundation for global food security, agricultural policies and subsidies should be reformed to encourage farmers to adopt regenerative,soil-building practices.

关键词： Agriculture soil security food security regenerative

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Hybrid LES/rANS Simulations of Compressible Flow in a Linear Cascade of Flat blade Profiles

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Journal of Thermal Science 2024年第5期33卷 1839-1850页

作者： Jaromír PrIHODA Petr STrAKA david SIMUrDA Petr SIDLOF Jan LEPICOVSKY Institute of Thermomechanics of the Czech Academy of Sciences Dolejskova 1402/518200 Prague 5Czech Republic Aerospace research and Test Centre Beranovych 13019905 PragueCzech Republic Technical University of Liberec Faculty of MechatronicsStudentska 246117 Liberec 1Czech Republic

The paper reports on 3D numerical simulations of unsteady compressible airflow in a blade cascade consisting of flat profiles using a hybrid LES/rANS approach including a transition *** a first step towards simulation of blade flutter in turbomachinery,various incidence angle offsets of the middle blade were *** simulations were run for the flow regime characterized by outlet isentropic Mach number M_(is)=0.5and zero *** results of the LES/rANS simulations(pressure and Mach number distributions)were compared to a baseline rANS model,and to experimental data measured in a high-speed wind *** numerical results show that both methods overpredict flow separation taking place at the leading *** this regard,the hybrid LES/rANS method does not provide superior results compared to the traditional rANS ***,the LES/rANS results also capture vortex shedding from the blunt trailing *** frequency of the trailing edge vortex shedding in CFD simulations matches perfectly the spectral peak recorded during wind tunnel measurements.

关键词： numerical simulation blade cascade hybrid LES/rANS

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Thermal conductivity suppression in uranium-doped thorium dioxide due to phonon-spin interactions

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Journal of Materiomics 2024年第3期10卷 709-715页

作者： Zilong Hua Saqeeb Adnan Amey r.Khanolkar Karl rickert david b.Turner Timothy A.Prusnick J.Matthew Mann david H.Hurley Marat Khafizov Cody A.Dennett Materials Science and Engineering Department Idaho National LaboratoryIdaho FallsID83415USA Department of Mechanical and Aerospace Engineering The Ohio State UniversityColumbusOH43210USA Kbr DaytonOH45431USA Azimuth Corporation FairbornOH45324USA Air Force research Laboratory Wright-Patterson AFBOH45433USA Department of Nuclear Science and Engineering Massachusetts Institute of TechnologyCambridgeMA02139USA

In this work,impact of low level of uranium(U)atom substitution on thermal conductivity of thorium dioxide(ThO_(2))is ***_(2)is an electronic insulator with a wide optical band-gap and no unpaired electrons whose thermal transport is governed by phonons.U-substitution introduces unpaired f-electrons resulting in paramagnetic behavior of UeThO_(2)at room temperature,which significantly suppresses its thermal conductivity.A single crystal of UeThO_(2)with graded composition of U is grown using a hydrothermal synthesis method,and thermal conductivity measurements are performed in re-gions with uniform composition of U at levels of 0%,6%,9%and 16%.Measured thermal conductivity profiles over 77e300 K temperature range are analyzed using an analytical expression for phonon-mediated thermal transport based on Klemens-Callaway *** dependent thermal con-ductivity is found to deviate significantly from the rayleigh scattering trend expected for a simple substitutional point defect with a small perturbation to mass and interatomic *** the resonant scattering term,observed large suppression of thermal conductivity at low temperatures can be closely ***,the extracted phonon-spin coupling constants imply a nonlinear relation of phonon-spin interaction intensity with respect to U doping *** study reveals how phonon-spin scattering contributed by unpaired f-electrons in U atoms influences thermal transport in the UeThO_(2)system.

关键词： Phonon-spin interactions Thermal conductivity UdThO_(2)system

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Temporal variability and sources of PFAS in the rio Grande,New Mexico through an arid urban area using multiple tracers and highfrequency sampling

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Emerging Contaminants 2024年第3期10卷 205-220页

作者： Kimberly r.beisner rebecca E.Travis david A.Alvarez Larry b.barber Jacob A.Fleck Jeramy r.Jasmann U.S.Geological Survey 6700 Edith Blvd NEAlbuquerqueNM87113USA U.S.Geological Survey 4200 New Haven RoadColumbiaMO65201USA U.S.Geological Survey 3215 Marine St.BoulderCO80303USA U.S.Geological Survey 6000 J St.Placer Hall.SacramentoCA95819USA

Per-and polyfluoroalkyl substances(PFAS)are ubiquitous in the environment but sources are not well defined for temporal and spatial aspects within an urban environment,and especially for an arid urban environment subject to seasonal short term high-intensity precipitation events.A focused diel sampling was conducted in the summer of 2021 to assess the temporal and spatial variability of PFAS in the rio Grande near Albuquerque,New Mexico and showed an order of magnitude increase of PFAS as it flows through the Albuquerque urban *** samples were collected at two different locations on the rio Grande in addition to wastewater treatment plant(WWTP)effluent that discharges directly to the rio Grande between the sampling ***-term high-intensity precipitation events occurred during the study period and mobilized PFAS from urban *** organic matter composed of tryptophan-like organic substances and refined fuel and fuel byproducts,characteristic of an urban signature,were also related to the precipitation *** PFAS in discharge from the WWTP was consistent over a 24-h period with slight differences in some *** presence on the rio Grande downstream of the WWTP was evidenced by a gadolinium anomaly as well as increases in several other trace elements,total dissolved nitrogen,and fluorescence indicators,in addition to *** varied depending on source contribution,where urban runoff was associated with PFOA,PFOS,and PFbA,whereas PFHxA and PFPeA were associated with wastewater *** addition,passive polar organic chemical integrative samplers(POCIS)using hydrophilic-lipid balance(HLb)sorption media were deployed for a month at two locations on the rio Grande to assess longer term PFAS *** POCIS results show some compounds(PFPeA and PFHpA)were greater than the average concentration from discrete samples,whereas other compounds(PFHxA,PFOA,PFDA,and PFNA)were lower in the POCIS,and PFOS was very simila

关键词： wastewater rio runoff

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A metabolic signalling role for arginine in liver cancer

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Life Metabolism 2024年第1期3卷 1-3页

作者： david Sokolov Lucas b.Sullivan Human biology Division Fred Hutchinson Cancer CenterSeattleWA 98109United States

In addition to their canonical roles in biosynthetic pathways,metabolites can be active participants in oncogenic signal-ling,but our understanding of these signalling mechanisms is *** a recent article published in Cell,Mossmann et *** a novel signalling role for accumulated arginine in hepato-cellular carcinoma(HCC)mediated by the rNA splicing factor and transcriptional modifier rNA-binding protein 39(rbM39).

关键词： incomplete cancer

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Single-atom Pt on carbon nanotubes for selective electrocatalysis

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Carbon Energy 2024年第1期6卷 63-71页

作者： Samuel S.Hardisty Xiaoqian Lin Anthony r.J.Kucernak david Zitoun Department of Chemistry Bar Ilan Institute of Nanotechnology and Advanced Materials(BINA)Bar Ilan UniversityRamat GanIsrael Department of Chemistry Molecular Science Research HubImperial College LondonLondonUK

Utilizing supported single atoms as catalysts presents an opportunity to reduce the usage of critical raw materials such as platinum,which are essential for electrochemical reactions such as hydrogen oxidation reaction(HOr).Herein,we describe the synthesis of a Pt single electrocatalyst inside single-walled carbon nanotubes(SWCNTs)via a redox *** via electron microscopy,X-ray photoelectron microscopy,and X-ray absorption spectroscopy show the single-atom nature of the *** electrochemical behavior of the sample to hydrogen and oxygen was investigated using the advanced floating electrode technique,which minimizes mass transport limitations and gives a thorough insight into the activity of the *** single-atom samples showed higher HOr activity than state-of-the-art 30%Pt/C while almost no oxygen reduction reaction activity in the proton exchange membrane fuel cell operating *** selective activity toward HOr arose as the main fingerprint of the catalyst confinement in the SWCNTs.

关键词： confinement electrocatalysis hydrogen platinum single atom catalysts

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Liver abnormalities following SArS-CoV 2 infection in children 1 to 10 years of age

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Family Medicine and Community Health 2024年第1期12卷 28-35页

作者： Pauline Terebuh Veronica r Olaker Ellen K Kendall david C Kaelber rong Xu Pamela b Davis Center for Artificial Intelligence in Drug Discovery Case Western Reserve UniversityClevelandOHUSA The Center for Clinical Informatics research and Education The MetroHealth SystemClevelandOHUSA Department of Medicine PediatricsDepartment of Population and Quantitative Health SciencesCase Western Reserve UniversityClevelandOHUSA Center for Community Health Integration Case Western Reserve UniversityClevelandOHUSA

Objective beginning in October 2021 in the USA and elsewhere,cases of severe paediatric hepatitis of unknown aetiology were identified in young *** the adenovirus and adenovirus-associated virus have emerged as leading aetiological suspects,we attempted to investigate a potential role for SArS-CoV 2 in the development of subsequent liver *** We conducted a study using retrospective cohorts of deidentified,aggregated data from the electronic health records of over 100 million patients contributed by US healthcare *** Compared with propensity score matched children with other respiratory infections,children aged 1-10 years with COVID-19 had a higher risk of elevated transaminases(Hr(95%CI)2.16(1.74 to 2.69))or total bilirubin(Hr(95%CI)3.02(1.91 to 4.78)),or new diagnoses of liver diseases(Hr(95%CI)1.67(1.21 to 2.30))from 1 to 6 months after *** with pre-existing liver abnormalities,liver abnormalities surrounding acute infection,younger age(1-4 years)or illness requiring hospitalisation all had similarly elevated *** who developed liver abnormalities following COVID-19 had more pre-existing conditions than those who developed abnormalities following other *** These results indicate that SArS-CoV 2 may prime the patient for subsequent development of liver infections or non-infectious liver *** rare(~1 in 1000),SArS-CoV 2 is a risk for subsequent abnormalities in liver function or the diagnosis of diseases of the liver.

关键词： elevated diagnosis subsequent

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Probing the bardeen-Kiselev black hole with the cosmological constant caused by Einstein equations coupled with nonlinear electrodynamics using quasinormal modes and greybody bounds

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Communications in Theoretical Physics 2024年第6期76卷 102-119页

作者： S r Wu b Q Wang Z W Long College of Physics Guizhou UniversityGuiyang 550025China College Pharmacy Guizhou University of Traditional Chinese MedicineGuiyang 550025China

In this work,we investigate a static and spherically symmetric bardeen-Kiselev black hole(bH)with the cosmological constant,which is a solution of the Einstein-non-linear Maxwell field *** compute the quasinormal frequencies for the bardeen-Kiselev bH with the cosmological constant due to electromagnetic and gravitational *** varying the bH parameters,we discuss the behavior of both real and imaginary parts of the bH quasinormal frequencies and compare these frequencies with the reissner-Nordström-de Sitter bH surrounded by quintessence(rN-dSQ).Interestingly,it is shown that the responses of the bardeen-Kiselev bH with the cosmological constant and the rN-dSQ under electromagnetic perturbations are different when the charge parameter q,the state parameter w and the normalization factor c are varied;however,for the gravitational perturbations,the responses of the bardeen-Kiselev bH with the cosmological constant and the rN-dSQ are different only when the charge parameter q is ***,compared with the gravitational perturbations,the electromagnetic perturbations can be used to understand nonlinear and linear electromagnetic fields in curved spacetime *** interesting observation is that,due to the presence of Kiselev quintessence,the electromagnetic perturbations around the bardeen-Kiselev bH with the cosmological constant damps faster and oscillates slowly;for the gravitational perturbations,the quasinormal mode decays slowly and oscillates *** also study the reflection and transmission coefficients along with the absorption cross section in the bardeen-Kiselev bH with the cosmological constant;it is shown that the transmission coefficients will increase due to the presence of Kiselev quintessence.

关键词： quasinormal modes greybody factors bardeen-Kiselev black hole with cosmological constant

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rational molecular design of efficient yellow-red dendrimer TADF for solution-processed OLEDs: a combined effect of substitution position and strength of the donors

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Science China Chemistry 2024年第5期67卷 1613-1623页

作者： Changfeng Si Dianming Sun Tomas Matulaitis david b.Cordes Alexandra M.Z.Slawin Eli Zysman-Colman Organic Semiconductor Centre EaStCHEM School of ChemistryUniversity of St AndrewsSt AndrewsKY169STUK

The development of high-performance solution-processed red organic light-emitting diodes(OLEDs) remains a challenge,particularly in terms of maintaining efficiency at high luminance. Here, we designed and synthesized four novel orange-red thermally activated delayed fluorescence(TADF) dendrimers that are solution-processable: 2GCz bP, 2DPACz bP, 2FbP2GCz and 2FbP2DPACz. We systematically investigated the effect of substitution position and strength of donors on the optoelectronic properties. The reverse intersystem crossing rate constant(krISC) of the emitters having donors substituted at positions 11and 12 of the dibenzo[a,c]phenazine(bP) is more than 10-times faster than that of compounds substituted having donors substituted at positions 3 and 6. Compound 2DPACz bP, containing stronger donors than 2GCz bP, exhibits a red-shifted emission and smaller singlet-triplet energy splitting, ΔE_(ST), of 0.01 e V. The solution-processed OLED with 10 wt% 2DPACz bP doped in m CP emitted at 640 nm and showed a maximum external quantum efficiency(EQE_(max)) of 7.8%, which was effectively maintained out to a luminance of 1,000 cd m-2. Such a device's performance at relevant display luminance is among the highest for solution-processed red TADF OLEDs. The efficiency of the devices was improved significantly by using 4Cz IPN as an assistant dopant in a hyperfluorescence(HF) configuration, where the 2DPACz bP HF device shows an EQEmaxof 20.0% at λEL of 605 nm and remains high at 11.8% at a luminance of 1,000 cd m-2, which makes this device one of the highest efficiency orange-to-red HF SP-OLEDs to date.

关键词： thermally activated delayed fluorescence solution-processing red OLEDs dibenzo[a,c]phenazine dendrimers

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