检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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(pid 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

Diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Animal Science and Biotechnology 2024年第2期15卷 733-748页

作者： Jianmin Chai Caleb p.Weiss paul A.Beck Wei Zhao Ying Li Jiangchao Zhao Guangdong provincial Key Laboratory of Animal Molecular Design and precise Breeding College of Life Science and EngineeringFoshan UniversityFoshanChina Division of Agriculture Department of Animal ScienceUniversity of ArkansasFayettevilleARUSA Department of Animal and Food Sciences Oklahoma State UniversityStillwaterOKUSA Institute of Feed Research of Chinese Academy of Agricultural Sciences Key Laboratory of Feed Biotechnology of the Ministry of Agriculture and Rural AffairsBeijing 100193China

Background Stocker cattle diet and management influence beef cattle performance during the finishing stage,but knowledge of the dynamics of the rumen microbiome associated with the host are lacking.A longitudinal study was conducted to determine how the feeding strategy from the stocker to the finishing stages of production affects the temporal dynamics of rumen *** the stocker phase,either dry hay or wheat pasture were provided,and three levels of monensin were *** calves were then transported to a feedlot and received similar finishing diets with or without *** microbial samples were collected on d 0,28,85 during the stocker stage(S0,S28 and S85)and d 0,14,28,56,30 d before slaughter and the end of the trial during the finishing stage(F0,F14,F28,F56,pre-Ba,and Final).The V4 region of the bacterial 16S rRNA gene of 263 rumen samples was *** Higher alpha diversity,including the number of observed bacterial features and the Shannon index,was observed in the stocker phase compared to the finishing *** bacterial amplicon sequence variants(ASVs)differentiating different sampling time points were *** treatments during the stocker stage temporally impact the dynamics of rumen *** example,shared bacteria,including Bacteroidales(ASV19)and Streptococcus infantarius(ASV94),were significantly higher in hay rumen on S28,S85,and F0,while Bacteroidaceae(ASV11)and Limivicinus(ASV15)were more abundant in *** affected rumen microbial composition at a specific *** to feedlot significantly influenced microbiome structure and diversity in hay-fed *** taxa associated with body weight were classified,and core microbiotas interacted with each other during the *** In summary,the temporal dynamics of the rumen microbiome in cattle at the stocker and finishing stage are influenced by multiple factors of the feeding *** at the stocker phase may t

关键词： Beef cattle Diet Feedlot phase Monensin Next-generation sequencing Rumen microbiota Stocker

post-fire recovery of puya raimondii, vegetation and birds in the puna of Huascarán National park, perú

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2024年第1期21卷 20-32页

作者： Mery L.SUNI Giovana p.VADILLO César ARANA Enoc JARA-pENA Letty SALINAS M.Estela pONCE paul M.RAMSAY plant physiology Laboratory Faculty of Biological SciencesUniversidad Nacional Mayor de San MarcosLima 15081Peru Natural History Museum Universidad Nacional Mayor de San MarcosLima 15072Peru Applied phytology Laboratory Faculty of Biological SciencesUniversidad Nacional Mayor de San MarcosLima 15081Peru Department of Statistics Faculty of Mathematical SciencesUniversidad Nacional Mayor de San MarcosLima 15081Peru Department of Chemical and Biological Sciences Universidad de las Américas PueblaSan Andrés Cholula CP Cholula CP 72810Mexico

A large fire of 233 ha in Huascarán National park in peru provided an opportunity to compare plant and bird responses in burned and nearby unburned zones of the puna. Heights and live diameters of flagship puya raimondii rosettes(assigned to four broad developmental phases), plant communities(66 species in 24 families and nine growth forms) and bird communities(77 species in six trophic guilds) were monitored after the fire. Although no mortality was observed, puya raimondii plants were affected by the fire, losing approximately 60% of their photosynthetic area across all developmental phases, but recovered quickly during the first two years after fire. The comparison of puya rosette recovery after fire was complicated by the changes in live rosette diameter for unburned plants, which showed plasticity of photosynthetic area linked to seasonal and annual fluctuations in precipitation in this relatively dry environment(decreased by 26% for mature adult plants over the study period). Fire caused an immediate change in the density, biomass and composition of vegetation. Although the species present remained similar, their abundances changed significantly immediately after the fire, with notable reductions in dominant tussock grasses. This provided opportunities for other plants, resulting in higher postfire diversity of plant species, genera, families and growth forms. In turn, the changes in vegetation after fire affected the composition of birds according to their trophic guild. Granivores largely disappeared,generalists were mostly unaffected, and other guilds showed a more complex response. As the vegetation recovered, most displaced birds returned within approximately one year.

关键词： Burning plant biomass Trophic guilds Andes Giant rosette plants

Exploring innovative synthetic solutions for advanced polymer-based electrochromic energy storage devices:phenoxazine as a promising chromophore

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第4期91卷 433-452页

作者： Catalin-paul Constantin Mihaela Balan-porcarasu Gabriela Lisa “petru poni”Institute of Macromolecular Chemistry Electroactive Polymers&Plasmochemistry Laboratory41A Grigore Ghica Voda AlleyIasi 700487Romania “Gh.Asachi”Technical University Iasi Faculty of Chemical EngineeringBd.Mangeron 71Iasi 700050Romania

The current investigation offers an innovative synthetic solution regarding electrochromic(EC)and energy storage applications by exploring phenoxazine(pOZ)***,three pOZ-based polymers(polyimide,polyazomethine,and polyamide)were synthesized to ascertain the superior *** polyamide exhibited remarkable attributes,including high redox stability during 500 repetitive CVs,optical contrast of 61.98%,rapid response times of 1.02 and 1.38 s for coloring and bleaching,EC efficiency of 280 cm^(2)C^(-1).and decays of the optical density and EC efficiency of only 12.18%and 6.23%after 1000 ***,the energy storage performance of polyamide pA was tested,for which the following parameters were obtained:74.7 F g^(-1)(CV,scan rate of 10 mV s^(-1))and 118 F g^(-1)(GCD,charging current of 0.1 A g^(-1)).Then,the polyamide was tested in EES devices,which yielded the following EC parameters:an optical contrast of 62.15%,response times of 9.24 and 5.01 s for coloring and bleaching,EC efficiency of 178 cm^(2)C^(-1),and moderate decays of 20.25%and 23.24%for the optical density and EC efficiency after 500 *** energy storage performance included a capacitance of 106 F g^(-1)(CV,scan rate of 0.1 mV s^(-1))and 9.23 F g^(-1)(GCD,charging current of 0.1 A g^(-1)),capacitance decay of 11.9%after500 cycles,and 1.7 V retention after 2 ***,two EES devices connected in series powered a 3 V LED for almost 30 s.

关键词： polymers phenoxazine Electrochromic Energy storage Electrochromi cenergy storage devices

The penetration depth of atomic radicals in tubes with catalytic surface properties

在线全文

学校读者我要写书评

暂无评论

plasma Science and Technology 2024年第7期26卷 157-164页

作者： Domen paul Miran MOZETIC Rok ZApLOTNIK Alenka VESEL Gregor pRIMC Denis DONLAGIC Jozef Stefan Institute Jamova Cesta 39Ljubljana 1000Slovenia Jozef Stefan International postgraduate School Jamova Cesta 39Ljubljana 1000Slovenia Faculty of Electrical Engineering and Computer Science University of MariborKoroska Cesta 46Maribor 2000Slovenia

Catalysis of molecular radicals is often performed in interesting experimental *** possible configuration is tubular *** radicals are introduced into the tubes on one side,and stable molecules are exhausted on the other *** penetration depth of radicals depends on numerous parameters,so it is not always feasible to calculate *** article presents systematic measurements of the penetration depth of oxygen atoms along tubes made from nickel,cobalt,and *** source of O atoms was a surfatron-type microwave *** initial density of O atoms depended on the gas flow and was 0.7×10^(21)m^(-3),2.4×10^(21)m^(-3),and 4.2×10^(21)m^(-3)at the flow rates of 50,300,and 600 sccm,and pressures of 10,35,and 60 pa,*** gas temperature remained at room temperature throughout the *** dissociation fraction decreased exponentially along the length of the tubes in all *** penetration depths for well-oxidized nickel were 1.2,1.7,and 2.4 cm,*** cobalt,they were slightly lower at 1.0,1.3,and 1.6 cm,respectively,while for copper,they were 1.1,1.3,and 1.7 cm,*** results were explained by gas dynamics and heterogeneous surface *** data are useful in any attempt to estimate the loss of molecular fragments along tubes,which serve as catalysts for the association of various radicals to stable molecules.

关键词： oxygen plasma penetration depth catalysis heterogeneous surface recombination atom loss

Inpatient management of iron deficiency anemia in pediatric patients with inflammatory bowel disease: A single center experience

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical pediatrics 2024年第1期13卷 107-117页

作者： Krishanth Manokaran Jonathan Spaan Giulio Cataldo Christopher Lyons paul D Mitchell Tatyana Sare LoriA Zimmerman paul A Rufo Center for Inflammatory Bowel Disease Boston Children's HospitalBostonMA 02115United States Institutional Centers for Clinical and Translational Research Boston Children's HospitalBostonMA 02115United States

BACKGROUND Screening for iron deficiency anemia(IDA)is important in managing pediatric patients with inflammatory bowel disease(IBD).Concerns related to adverse reactions may contribute to a reluctance to prescribe intravenous(IV)iron to treat IDA in this *** To track the efficacy and safety of IV iron therapy in treating IDA in pediatric IBD patients admitted to our *** A longitudinal observational cohort study was performed on 236 consecutive pediatric patients admitted to our tertiary IBD care center between September 2017 and December 2019.92 patients met study criteria for IDA,of which 57 received IV iron,17 received oral iron,and 18 were discharged prior to receiving iron *** patients treated with IV iron during their hospitalization experienced a significant increase of 1.9(±0.2)g/dL in mean(±SE)hemoglobin(Hb)concentration by the first ambulatory follow-up,compared to patients who received oral iron 0.8(±0.3)g/dL or no iron 0.8(±0.3)g/dL(p=0.03).One out of 57(1.8%)patients that received IV iron therapy experienced an adverse *** Our findings demonstrate that treatment with IV iron therapy is safe and efficacious in improving Hb and iron levels in pediatric patients with IDA and active IBD.

关键词： Iron deficiency anemia pediatric inflammatory bowel disease Intravenous iron therapy Inflammatory bowel disease

Understanding the catalysis of chromium trioxide added magnesium hydride for hydrogen storage and Li ion battery applications

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第3期12卷 1117-1130页

作者： D.pukazhselvan IhsanÇaha Catarina de Lemos Sergey M.Mikhalev Francis Leonard Deepak Duncan paul Fagg Department of Mechanical Engineering TEMA-Centre for Mechanical Technology and AutomationUniversity of AveiroAveiro 3810-193Portugal LASI-Intelligent Systems Associate Laboratory Guimarães 4800-058Portugal Nanostructured Materials Group International Iberian Nanotechnology Laboratory(INL)Avenida Mestre Jose VeigaBraga 4715-330Portugal

This study explores how the chemical interaction between magnesium hydride(MgH_(2))and the additive CrO_(3) influences the hydrogen/lithium storage characteristics of MgH_(2).We have observed that a 5 wt.%CrO_(3) additive reduces the dehydrogenation activation energy of MgH_(2) by 68 kJ/mol and lowers the required dehydrogenation temperature by 80℃.CrO_(3) added MgH_(2) was also tested as an anode in an Li ion battery,and it is possible to deliver over 90%of the total theoretical capacity(2038 mAh/g).Evidence for improved reversibility in the battery reaction is found only after the incorporation of additives with MgH_(2).In depth characterization study by X-ray diffraction(XRD)technique provides convincing evidence that the CrO_(3) additive interacts with MgH_(2) and produces Cr/MgO *** free energy analyses confirm the thermodynamic feasibility of conversion from MgH_(2)/CrO_(3) to MgO/Cr,which is well supported by the identification of Cr(0)in the powder by X ray photoelectron spectroscopy(XpS)*** high resolution transmission electron microscopy(HRTEM)and energy dispersive spectroscopy(EDS)we found evidence for the presence of 5 nm size Cr nanocrystals on the surface of MgO rock salt *** is also convincing ground to consider that MgO rock salt accommodates Cr in the *** observations support the argument that creation of active metal–metal dissolved rock salt oxide interface may be vital for improving the reactivity of MgH_(2),both for the improved storage of hydrogen and lithium.

关键词： Hydrogen storage Rechargeable batteries Binary hydrides Metal oxides Catalytic mechanism.

中国锂动力电池产业链污染调查评估及风险管控

在线全文

学校读者我要写书评

暂无评论

环境污染与防治 2024年第3期46卷 387-391,399页

作者：李媛时进钢陈楠张明博 paul p.J.Gaffney 生态环境部环境发展中心北京100029 中国科学院地理科学与资源研究所北京100101

在碳达峰、碳中和目标指引下,新能源汽车产业带动锂动力电池迅猛发展,锂动力电池全产业链包括上游锂资源开发利用与锂盐生产、中游锂动力电池原材料生产与锂动力电池制造、下游锂动力电池的回收与利用,其生产过程均对生态环境产生不同... 详细信息

在碳达峰、碳中和目标指引下,新能源汽车产业带动锂动力电池迅猛发展,锂动力电池全产业链包括上游锂资源开发利用与锂盐生产、中游锂动力电池原材料生产与锂动力电池制造、下游锂动力电池的回收与利用,其生产过程均对生态环境产生不同程度的影响。基于全国环境影响评价管理信息平台相关数据及产业链产排污特征分析,研究指出中国锂动力电池产业发展面临的环境风险,并提出针对性的建议。结果表明,上游锂资源扩产面临较大的生态环境风险,锂盐生产或影响区域环境空气质量;中游锂动力电池生产过程涉及多种重金属与有机物,存在环境风险;下游回收利用现状不容乐观;建议从环境准入、排污许可、企业环境主体责任等方面入手,加强全产业链的环境风险管控。

关键词：锂动力电池全产业链产污特征生态环境风险环境管理

Nonlinear Study on the Mechanical performance of Built-Up Cold-Formed Steel Concrete-Filled Columns under Compression

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第6期139卷 3435-3465页

作者： Oulfa Harrat Yazid Hadidane S.M.Anas Nadhim Hamah Sor Ahmed Farouk Deifalla paul O.Awoyera Nadia Gouider Civil Engineering Laboratory Faculty of TechnologyDepartment of Civil EngineeringBadji Mokhtar-Annaba UniversityP.O.Box 12Annaba23000Algeria Department of Civil Engineering Faculty of Engineering and TechnologyJamia Millia Islamia(A Central University)New Delhi110025India Civil Engineering Department University of GarmianKalar46021Iraq Department of Civil Engineering Harran UniversitySanliurfa63510Turkey Structural Engineering and Construction Management Department Future University in EgyptNew Cairo11835Egypt Department of Civil Engineering Covenant UniversityOta112233Nigeria

Given their numerous functional and architectural benefits,such as improved bearing capacity and increased resistance to elastic instability modes,cold-formed steel(CFS)built-up sections have become increasingly developed and used in recent years,particularly in the construction *** paper presents an analytical and numerical study of assembled CFS two single channel-shaped columns with different slenderness and configurations(backto-back,face-to-face,and box).These columns were joined by double-row rivets for the back-to-back and box configurations,whereas they were welded together for the face-to-face *** built-up columns were filled with ordinary concrete of good *** element models were applied,using ABAQUS software,to assess mechanical performance and study the influence of assembly techniques on the behavior of cold-formed columns under axial *** approaches based on Eurocode 3 and Eurocode 4 recommendations for un-filled and concrete-filled columns respectively were followed for the numerical analysis,and concrete confinement effects were also considered per American Concrete Institute(ACI)standards for face-to-face and box *** obtained results indicated a good correlation between the numerical results and the proposed analytical methodology which did not exceed 8%.The failure modes showed that the columns failed due to instabilities such as local and global buckling.

关键词： Cold-formed steel built-up sections slenderness rivets welded axial compression analytical approaches confinement buckling