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The relation between ductility at high temperature and solid solution in mg alloys

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Journal of magnesium and Alloys 2022年第1期10卷 241-256页

作者： D.F.Shi C.m.Cepeda-Jiménez m.T.Pérez-Prado Im DEA materials Institute C/Eric Ka ridel228906 GetafeMadridSpain Department of materials Science Polytechnic University of Madrid/Universidad Politecnica de MadridE.T.S.de Ingenieros de Caminos28040MadridSpain Department of Physical metallurgy CENIMCSICAv.Gregorio del Amo 828040 MadridSpain

This work investigates the effect of solid solution on ductility and on the activation of individual deformation mechanisms at moderate temperatures and at quasi-static strain rates in mg-Zn and mg-Al alloys. with that aim, four solid solution mg-Zn and mg-Al binary alloy ingots containing 1 and 2 wt.% solute atoms were subjected to hot rolling and subsequent annealing to generate polycrystals with similar average grain size and basal-type texture for each composition. The activity of the different slip systems after tensile testing at 150°C and at 250°C was evaluated in pure mg and in the alloys by EBSD-assisted slip trace analysis. In addition, segregation of Zn and Al atoms at grain boundaries during the thermo-mechanical processing was characterized by HAADF-STEm and EDX. It was found that while the addition of Al and Zn atoms to pure mg does not lead to major changes in the mechanical strength at the investigated temperatures, it does enhance ductility significantly, especially at 250℃. Our results show that this increase in ductility cannot be attributed to a higher activation of non-basal systems in the alloys, as reported earlier, as the incidence of non-basal systems is indeed considerably higher in pure mg. This work suggests, on the contrary, that the ductility increase may be attributed to the presence of a more homogenous basal activity in the alloys due to a lower degree of orientation clustering, to grain boundary solute segregation, and to a higher slip diffusivity at grain interiors.

关键词： magnesium Solute segregation Slip trace analysis Ductility Deformation mechanisms

wandering gravel-bed rivers and high-constructive stable channel sandy fluvial systems in the Ross River area,Yukon Territory,Canada

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Geoscience Frontiers 2011年第3期2卷 277-288页

作者： Darrel G.F.Long Grant w.Lowey Department of Earth Sciences Laurentian UniversitySudburyOntario P3E 2C6Canada Yukon Geological Survey EnergyMines and Resources.Government of YukonP.O.Box 2703(K102)WhitehorseYukon Y1A 2C6Canada

mid-Cretaceous strata within the Tintina Trench, 3 km west of the community of Ross River, contain evidence of deposition in two distinct, alternating, fluvial settings. Coal-bearing, mud-dominated strata are commonly associated with high-constructive sandy channel systems, with extensive overbank, levee and splay deposits. Channels are between 3 and 30 m wide and 0.4-7 m thick. They show repetitive development of side and in-channel bar-forms, as well as up-channel widening of the rivers by selective erosion of associated overbank and levee deposits. Levees extended for several hundred metres away from the channels. In this setting low-angle inclined stratification and epsilon cross stratification may reflect lateral migration of crevasse channels or small streams. The paucity of exposure prevents recognition of the channels as products of multiple channel anastomosed systems or single channel high-constructive systems. Gravel-dominated strata, inter-bedded with, and overlying coal-bearing units, are interpreted as deposits of wandering gravel-bed rivers, with sinuosity approaching 1.4. In most exposures they appear to be dominated by massive and thin planar-bedded granule to small pebble conglomerates, which would traditionally be interpreted as sheet-flood or longitudinal bar deposits of a high-gradient braided stream or alluvial fan. Architectural analysis of exposures in an open-pit shows that the predominance of flat bedding is an artefact of the geometry of the roadside exposures. In the pit the conglomerates are dominated by large scale cross stratification on a scale of 1-5.5 m. These appear to have developed as downstream and lateral accretion elements on side-bars and on in-channel bars in water depths of 2-12 m. Stacking of strata on domed 3rd order surfaces suggests development of longitudinal in-channel bar complexes similar to those observed in parts of the modern Rhone River system. mudstone preserved in some of the channels reflects intervals of ch

关键词： Anastomosing rivers wandering gravel-bedrivers Fluvial architecture Cretaceous Yukon

Rare earth oxides doped NiO/γ-Al_2O_3 catalyst for oxidative dehydrogenation of cyclohexane

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Journal of Rare Earths 2015年第6期33卷 611-618页

作者： Hany m.AbdelD ayem m.Faiz Hesham S.Abdel-Samad Salah A.Hassan Center of Research Excellence in Petroleum Refining & Petrochemicals (CoR E-PRP) King Fahd University of Petroleum & Minerals Chemistry Department College of Science King Faisal University Chemistry Department Faculty of Science Ain Shams University Surface Science Laboratory Physics Department King Fahd University of Petroleum &Minerals Department of Basic Sciences and Technology Community College Taibah University

The effect of rare earth oxides （RE=Ce, La, Gd, and Dy） doping of alumina support in NiO/7-A1203 system was investi- gated on its catalytic performance in oxidative dehydrogenation （ODH） of cyclohexane. The physicochemical properties of various samples were followed up through N2 physisorption, temperature programmed reduction （H2-TPR）, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and potentiometric acid-base titration techniques. In the parent NiO/y-A1203 catalyst, Ni species were found to be strongly interacted with alumina surface. Addition of rare earth dopants to ）＇-A1203 in the catalyst system affected the nickel-alumina interaction and resulted in significant modifications in the catalytic performances in the ODH reaction. The results re- vealed the beneficial role of both La203 and Gd2Os doping in enhancing the ODH catalytic activity and selectivity to cyclohexene. H2-TPR and XPS results indicated that majority of Ni species in NiO/La203 modified T-A1203 were more weakly interacted with La203 and alumina whereas both NiO like species and nickel aluminate were present on the surface. Doping with cerium or dyspro- sium increased the nickel-support interaction and led to a decrease in surface nickel concentration. In case of doping with Ce, surface concentration of cerium oxide was higher than those of the other RE oxides; the doped catalyst reached its steady state activity faster than the other catalysts. The acid-base results suggested that RE metals were interacted most likely with acidic surface hydroxyl groups. The degree of nickel-alumina interaction decreased in the following order： LaAI〉GdAI〉CeAI〉DyA1.

关键词： nickel oxide rare-earth oxides doping Ni-A1203 interaction surface acidity oxidative dehydrogenation cyclohexane rare earths

Sexual dimorphism in cranial shape and size in geomyoid rodents:multivariate and evolutionary perspectives

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Current Zoology 2022年第4期68卷 469-487页

作者： Jonathan J m Calede Andrew Brown Department of Evolution Ecologyand Organismal BiologyThe Ohio State University318 W.12th Ave.300 Aronoff LaboratoryColumbusOH 43210USA The Ohio State University at marion 1459 Mount Vernon AvenueMarionOH 43302USA College of Veterinary medicine Texas A&M University660 Raymond Stotzer PkwyCollege StationTX 77843USA

Geomyoid rodents provide a great study system for the analysis of sexual *** are polygynic and many inhabit harsh arid environments thought to promote sexual *** fact,there has been extensive work published on the sexual size dimorphism of individual populations and species within this rodent ***,little work has been undertaken to assess the evolutionary patterns and processes associated with this sexual *** use multivariate analyses of cranial measurements in a phylogenetic framework to determine the distribution of size and shape dimorphism among geomyoids and test for Rensch’s *** results suggest that sexual dimorphism is more common in geomyids than heteromyids,but it is not in fact *** is evidence for variation in sexual dimorphism across ***,in many taxa,geographic variation appears to overwhelm existing sexual *** find support for the repeated independent evolution of shape and size dimorphism across geomyoid taxa,but we do not find support for an association between size and shape *** is no evidence for Rensch’s rule in geomyoids,whether at the superfamily or family ***,our findings suggest that there is no single explanation for the evolution of sexual dimorphism in geomyoids and that,instead,it is the product of numerous evolutionary *** studies incorporating phylogenetic relationships will be necessary to paint a more complete picture of the evolution of sexual dimorphism in geomyoids.

关键词： Geomyidae Heteromyidae phylogenetic comparative methods morphometrics Rensch’s rule

Oligomeric Acetylenic Sulfides and Platinum (Ⅱ) Complexes

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厦门大学学报（自然科学版） 1999年第S1期38卷 301-301页

作者： Albertw.m.Lee AnissaB.w.Yeung mabelS.m.Yuen DepartmentofChemistry HongKongBaptistUniversityKowloonTongKowloonHongKongDepartmentofChemistryHongKongBaptistUniversityKowloonTongKowloonHongKongDepartmentofChemistryHongKongBaptistUniversityKowloonTongKowloonHongKong

more than a simple egg:Underlying mechanisms of cold tolerance in avian embryos

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Avian Research 2023年第2期14卷 267-280页

作者： Ibrahim m.Ahmad Dongming Li Hebei Key Laboratory of Animal Physiology Biochemistry and Molecular BiologyCollege of Life SciencesHebei Normal UniversityShijiazhuang050024China Hebei Collaborative Innovation Center for Eco-Environment Hebei Normal UniversityShijiazhuang050024China

Avian embryos,which develop within eggs,exhibit remarkable tolerance to extremely low *** being a common trait among all birds,the mechanisms underlying this cold tolerance in avian embryos remain largely *** gain a better understanding of this phenomenon and the coping mechanisms involved,we reviewed the literature on severe cold tolerance in embryos of both wild and domestic *** found that embryos of different bird orders exhibit tolerance to severe cold during their *** response to cold stress,embryos slow down their heartbeat rates and *** severe cold temperatures,embryos can suspend these processes,entering a torpid-like state of cardiac *** compensate for these developmental delays,embryos extend their regular incubation *** on their embryonic age,embryos of all bird species can tolerate acute severe cold regimes;only a few tolerate chronic severe cold *** also discussed various extrinsic and intrinsic factors that affect the tolerance of bird embryos to low temperatures before and after *** tolerance appears to be a heritable trait shared by wild and domestic embryos of all bird classes,regardless of egg size or development(altricial/precocial).Driven by environmental variability,cold tolerance in avian embryos is an optimal physiological and ecological strategy to mitigate the adverse effects of cold conditions on their development in response to fluctuating environmental temperatures.

关键词： Acute cold tolerance Avian embryo Chronic cold tolerance Embryonic development Hatching success Incubation period

Ancient deep roots for mesozoic world-class gold deposits in the north China craton:An integrated genetic perspective

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Geoscience Frontiers 2020年第1期11卷 203-214页

作者： Cheng-Xue Yang m.Santosh School of Earth Sciences and Resources China University of Geosciences(Beijing)Beijing 100083China Department of Earth Sciences University of AdelaideAdelaideSA 5005Australia Key Lab of Submarine Geosciences and Prospecting Techniques Ministry of EducationCollege of Marine GeosciencesOcean University of ChinaQingdao 266100China Yonsei Frontier Lab Yonsei UniversitySeoul 03722Republic of Korea

The North China Craton(NCC)hosts some of the world-class gold deposits that formed more than 2 billion years after the major orogenic cycles and *** diverse models for the genesis of these deposits remain equivocal,and mostly focused on the craton margin examples,although synchronous deposits formed in the interior *** we adopt an integrated geological and geophysical perspective to evaluate the possible factors that contributed to the formation of the major gold deposits in the *** the Archean tectonic framework of the NCC,the locations of the major gold deposits fall within or adjacent to greenstone belts or the margins of *** the Paleoproterozoic framework,they are markedly aligned along two major collisional sutures-the Trans North China Orogen and the Jiao-Liao-Ji *** the mesozoic intrusions hosting these deposits do not carry adequate signals for the source of gold,we explore the deep roots based on available geophysical *** show that the gold deposits are preferentially distributed above zones of uplifted mOHO and shallow LAB corresponding to thinned crust and eroded sub-lithospheric mantle,and that the mineralization is located above regions of high heat flow representing mantle *** NCC was at the center of a multi-convergent regime during the mesozoic which intensely churned the mantle and significantly en riched *** geophysical data on moho and LAB upwarp from the centre towards east of the craton is more consistent with paleo-Pacific slab subduction from the east exerting the dominant control on lithospheric *** on these results,and together with an evaluation of the geochemical and isotopic features of the mesozoic magmatic intrusions hosting the gold mineralization,we propose a genetic model that invokes reworking of ancient Au archives preserved in the lower crust and metasomatised upper mantle and which were generated through multiple subduction,underplating and cumulation ev

关键词： Gold metallogeny Subduction tectonics Lithospheric thinning mantle metasomatism North China craton

Laser-Plasma Interaction in Presence of an Obliquely External magnetic Field:Application to Laser Fusion without Radioactivity

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Communications in Theoretical Physics 2016年第8期65卷 237-243页

作者： m.mobaraki S.Jafari Department of Physics University of Guilan

In this paper, the nonlinear interaction of ultra-high power laser beam with fusion plasma at relativistic regime in the presence of obliquely external magnetic field has been studied. Imposing an external magnetic field on plasma can modify the density profile of the plasma so that the thermal conductivity of electrons reduces which is considered to be the decrease of the threshold energy for ignition. To achieve the fusion of Hydrogen–Boron(HB) fuel,the block acceleration model of plasma is employed. Energy production by HB isotopes can be of interest, since its reaction does not generate radioactive tritium. By using the inhibit factor in the block model acceleration of plasma and maxwell's as well as the momentum transfer equations, the electron density distribution and dielectric permittivity of the plasma medium are obtained. Numerical results indicate that with increasing the intensity of the external magnetic field, the oscillation of the laser magnetic field decreases, while the dielectric permittivity increases. moreover, the amplitude of the electron density becomes highly peaked and the plasma electrons are strongly bunched with increasing the intensity of external magnetic field. Therefore, the magnetized plasma can act as a positive focusing lens to enhance the fusion process. Besides, we find that with increasing θ-angle(from oblique external magnetic field) between 0 and 90°, the dielectric permittivity increases, while for θ between 90° and 180°, the dielectric permittivity decreases with increasing θ.

关键词： laser-plasma interaction external magnetic field laser fusion HB fuel

Integrative Oncology in Australia

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Chinese Journal of Integrative medicine 2011年第4期17卷 246-250页

作者： Daniel weber Janelle m wheat Geoffrey m Currie Faculty of Science Charles Sturt UniversityWagga Wagga Australia Panaxea medicine SydneyAustralia Oncology Section World Federation of Chinese Medical Societies Faculty of Science Charles Sturt UniversityWagga WaggaAustralia Centre for Research in Complex Systems Charles Sturt UniversityWagga WaggaAustralia Australian School of Advanced medicine Macquarie UniversitySydneyAustralia

The use of alternative medicine（Am） in Australia dates back to its earliest times,with the indigenous medicine of the aboriginal peoples and the folk medicine of the early English *** has until recently existed quite separately from western biomedicine（wB） and there has been little integration of the two ***,referred to as complementary medicine（Cm）,there has been a movement over the last 20 years to include Cm in wB mainstream *** degrees of success have been reported but for the discipline of *** oncology（mO） in Australia is demanding Cm provide high levels of evidence for any inclusion in cancer *** are just now the beginnings of this integration, particularly as Cm is now being taught in the public university system to a PhD level as well as the public demand for their medical doctors to communicate with their Cm *** specialists are now open to a dialogue with their Cm counterparts.

关键词： alternative medicine complementary and alternative medicine complementary and integrative therapies complementary medicine medical oncology traditional Chinese medicine traditional complementary medicine western biomedicine