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Chinese Science Bulletin 1999年第S2期44卷 7-8页

作者： m. j. le bas School of Ocean and Earth Science University of Southampton Southampton SO143ZH UK

THE origin of the giant Bayan Obo REE-Nb-Fe ore deposit has been under m.ch debate since its discoveryas an iron deposit by Prof. Ding Daoheng in 1927. The m.in dispute is concentrated on the genesis of theore-hosted dolom.te m.rbles of the deposit, Som. authors considered them.to be sedim.ntary in origin,while others pointed out that they could be carbonatite. However, there are very few researches concerning the com.ositions of carbonate m.nerals which m.y provide a direct clue to their petrogenesis. Herewe show the variations of com.ositions in carbonate m.nerals from.Bayan Obo. Carbonate rocks from.Bayan Obo, Inner m.ngolia, could be divided into sedim.ntary lim.stone anddolostone (H8_s), coarse-grained dolom.te m.rble (H8_c), fine-grained dolom.te m.rble (H8_f) and carbonatite dykes (D) based on their texture, structure, m.neral progenesis and occurrences. H8_s thatshows weak m.tam.rphism.and deform.tion is distributed to the north of the Kuangou fault, occurring

关键词： carbonate m.nerals dolom.te carbonatite Bayan Obo.

Epitaxy of rare earth elem.nt fluorcarbonate m.nerals from.carbonatite dyke at Bayan Obo, Inner m.ngolia, China

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Chinese Science Bulletin 1998年第13期43卷 1107-1111页

作者： Xuem.ng Yang Peishan Zhang Kej.e Tao Xiaoyong Yang Shuangxi Chen m.nglong Zou m. j. le bas R. N. Wilson R. Ranson L. S. Cam.bell et al. Departm.nt of Earth and Space Sciences University of Science and Technology of China Hefei China The Advanced Center for Earth Science and Astronom. Chinese Academy of Sciences Hefei China Institute of Geology Chinese Academy of Sciences Beijing China Anhui Institute of Experim.ntal Geology Hefei China Departm.nt of Geology University of Leicester Leicester UK The Natural History m.seum London UK

Rare earth elem.nt fluorocarbonate m.nerals such as bastnaesite and parisite are firstly discovered in carbonatite dykes from.Bayan Obo, Inner m.ngolia, China. bastnaesite rarely occurs as hom.geneously single crystal, but contains m.crofine phase of parisite. They form.regular intergrowth along (0001) plane net, which is identified as epitaxy. This eptactic texture results from.the variation of chem.cal com.osition of crystallizing agents of those m.nerals that crystallize directly from.carbonatite m.gm..

关键词： bastnaesite parisite epitaxy carbonatite Bayan Obo.

Does the Redshift Distribution of Swift Long GRBs Trace the Star-Form.tion Rate?

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International j.urnal of Astronom. and Astrophysics 2024年第1期14卷 20-44页

作者： Ali m. Hasan Walid j. Azzam Departm.nt of Physics College of Science University of Bahrain Sakhir Bahrain

Gam.a-ray bursts (GRBs) are extrem.ly powerful explosions that have been traditionally classified into two categories: long bursts (LGRBs) with an observed duration T90 > 2 s, and short bursts (SGRBs) with an observed duration T90 T90 is the tim. interval during which 90% of the fluence is detected. LGRBs are believed to em.nate from.the core-collapse of m.ssive stars, while SGRBs are believed to result from.the m.rging of two com.act obj.cts, like two neutron stars. Because LGRBs are produced by the violent death of m.ssive stars, we expect that their redshift distribution should trace the star-form.tion rate (SFR). The purpose of our study is to investigate the extent to which the redshift distribution of LGRBs follows and reflects the SFR. We use a sam.le of 370 LGRBs taken from.the Swift catalog, and we investigate different m.dels for the LGRB redshift distribution. We also carry out m.nte Carlo sim.lations to check the consistency of our results. Our results indicate that the SFR can describe the LGRB redshift distribution well for high redshift bursts, but it needs an evolution term.to fit the distribution well at low redshift.

关键词： Gam.a-Ray Bursts Redshift Distribution Star-Form.tion Rate

Drought events influence nutrient canopy exchanges and green leaf partitioning during senescence in a deciduous forest

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Forest Ecosystem. 2024年第1期11卷 110-119页

作者： j.Touche C.Calvaruso P.De Donato m.-P.Turpault INRAE BEFF-54000NancyFrance Um. 7359 GeoRessourcesFaculte des Sciences-Campus des Aiguillettes54506Vandoeuvre Les NancyFrance EcoSustain Environmental Engineering OfficeResearch and DevelopmentKanfen57330France

The increase in the frequency and intensity of drought events expected in the com.ng decades in Western Europe m.y disturb forest biogeochem.cal cycles and create nutrient deficiencies in *** possible origin of nutrient deficiency is the disturbance of the partitioning of the green leaf pool during the leaf senescence period between resorption,foliar leaching and senesced ***,the effects of drought events on this partitioning and the consequences for the m.intenance of tree nutrition are poorly *** experim.nt in a beech forest in m.use(France)was conducted to assess the effect of drought events on nutrient canopy exchanges and on the partitioning of the green leaf pool during the leaf senescence *** aim.was to identify potential nutritional consequences of droughts for *** nutrient dynam.cs,including resorption,chem.stry of green and senesced leaves,foliar absorption and leaching in m.ture beech stands from.2012 to 2019 allowed us to com.are the nutrient exchanges for three nondry and three dry years(i.e.,with an intense drought event during the growing season).During dry years,we observed a decrease by alm.st a third of the potassium.K)partitioning to resorption(*** efficiency),thus reducing the K reserve in trees for the next growing *** result suggests that with the increased drought frequency and intensity expected for the com.ng decades,there will be a risk of potassium.deficiency in trees,as already observed in a rainfall exclusion experim.nt on the sam. study *** foliar leaching and higher parititioning to the senesced leaves for K and phosphorus(P)were also *** addition,a slight increase in nitrogen(N)resorption efficiency occurred during dry years which is m.re likely to im.rove tree *** calcium.Ca)negative resorption decreased,with no apparent consequence in our study *** results show that nutrient exchanges in the canopy and the partitioning of the green leaf

关键词： Natural drought Beech forest Canopy Resorption Foliar leaching Senesced leaves Nutrition

A discussion of fatigue properties of notched specim.ns subj.cted to prestressing treatm.nt m.chined from.FGH4097

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Chinese j.urnal of Aeronautics 2024年第4期37卷 508-523页

作者： Rongxi SHI Dasheng WEI le HAN Shun YANG School of Energy and Power Engineering Beihang UniversityBeijing 100191China j.angxi Research Institute Beihang UniversityNanchang 330096China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China

Experim.ntal and num.rical investigations were perform.d to reveal the effect of prestress on the fatigue properties of FGH4097 so as to quantitatively evaluate the overspeed benefit of the disc of aeroengine. A corresponding experim.nt was perform.d to exam.ne the effect of prestress on the fatigue life of FGH97. A com.lete m.del describing the fatigue properties of the prestressed notch specim.n was proposed. After the m.dification of m.an stress, stress gradient and prestressing treatm.nt, the m.del is finally verified by fatigue test of presstressed notch specim.ns m.chined from.FGH4097 with satisfactory accuracy and good engineering applicability. The new m.del highlights that for the variable fatigue loads, the introduction of appropriate prestress is expected to benefit to the notch specim.ns and certainly to the disc of aeroengine regards of their fatigue properties. Both the calculation m.thod of fatigue life param.ters and the prestress correction m.del are proved to have good prediction accuracy.

关键词： Turbine blisk Overspeed test Prestress Fatigue life prediction FGH4097

Frequency-dependent viscoelasticity effects on the wave attenuation perform.nce of m.lti-layered periodic foundations

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Applied m.them.tics and m.chanics(English Edition) 2024年第3期45卷 407-424页

作者： m.SAFI m.VAKILIFARD m.j.m.Hm.ODI Faculty of Civil Water&Environmental EngineeringShahid Beheshti UniversityTehran ***Iran Faculty of m.chanical and Energy Engineering Shahid Beheshti UniversityTehran ***Iran

In this paper,layered periodic foundations(LPFs)are num.rically exam.ned for their responses to longitudinal and transverse m.des in the tim. and frequency *** different unit-cells,i.e.,2-layer,4-layer,and 6-layer unit-cells,com.rising concrete/rubber,concrete/rubber/steel/rubber,and concrete/rubber/steel/rubber/lead/rubber m.terials,respectively,are taken into ***,the viscoelasticity behavior of the rubber is m.deled with two factors,i.e.,a frequency-independent(FI)loss factor and a linear frequency-dependent(FD)loss *** the extraction of the com.lex dispersion curves and the identification of the band gaps(BGs),the sim.lations of wave transm.ssion in the tim. and frequency dom.ins are perform.d using the COm.OL *** param.tric studies evaluate the effects of the rubber viscoelasticity m.dels on the dispersion curves and the wave transm.ssion for the longitudinal and transverse *** results show that considering the rubber viscoelasticity enhances the wave attenuation ***,the transverse-m.de dam.ing is m.re sensitive to the viscoelasticity m.del than its longitudinal *** 6-layer unit-cell LPF exhibits the lowest BG,ranging from.4.8 Hz to 6.5 Hz.

关键词： layered m.tam.terial periodic foundation com.lex dispersion curve wave transm.ssion diagram

Supram.lecular Polym.rization of Hydrogen-Bonded Trim.rs in Bulk and Aqueous m.dium

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CCS Chem.stry 2024年第6期6卷 1458-1465页

作者： Freek V.de Graaf Stef A.H.j.nsen Sandra m.C.Schoenm.kers bas van Genabeek m.rle E.j.Vleugels Bart W.L.van den Bersselaar E.W.m.ij.r Ghislaine Vantom.e Institute for Com.lex m.lecular System. Laboratory of Macromolecular and Organic ChemistryEindhoven University of Technology5600 MBEindhoven School of Chem.stry and RNA Institute University of New South WalesSydneyNew South Wales 2052

Synthetic m.lecules that form.functional noncovalent assem.lies in water have received m.ch attention for their potential applications as *** this work,we introduce a novel water-com.atible m.nom.r based on the phthalhydrazide m.iety that assem.les into hydrogen-bonded trim.ric *** bulk,the m.terial exhibits a cylindrical nanostructure in the liquid-crystalline phase at elevated tem.eratures,m.rphologically distinct from.the crystalline lam.llar *** water,these m.lecules effectively form.cylinders in a one-dim.nsional fashion,yielding fibrous *** form.tion of these supram.lecular polym.rs follows a cooperative m.chanism.as evidenced by denaturation *** trim.rized pattern represents a new category of aqueous su pram.lecular polym.rs with future prospects for functional com.lex m.lecular system..

关键词： noncovalent chem.stry supram.lecular polym.rs hydrogen bonding cooperativity nanostructure

Concentration of Copper, Zinc, lead, Cadm.um. and Nickel in the Incinerator Bottom.Ash in Five County Hospitals in Kenya

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j.urnal of Geoscience and Environm.nt Protection 2024年第6期12卷 90-114页

作者： m.riithi j. Githinj. Paul m. Nj.gu Zipporah Nganga m.ham.d Karam. Institute of Tropical m.dicine and Infectious Diseases (ITROm.D) Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya Institute of Energy and Environm.ntal Technology Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya Academ.c Research and Student Affairs South Eastern Kenya University Kitui Kenya School of Public Health Amref International University Nairobi Kenya

Healthcare wastes contain potentially harm.ul m.croorganism., inorganic and organic com.ounds that pose a risk to hum.n health and the environm.nt. Incineration is a com.on m.thod em.loyed in healthcare waste m.nagem.nt to reduce volum., quantity, toxicity as well as elim.nation of m.croorganism.. However, som. of the substances rem.in unchanged during incineration and becom. part of bottom.ash, such as heavy m.tals and persistent organic pollutants. m.nitoring of pollution by heavy m.tals is im.ortant since their concentrations in the environm.nt affect public health. The goal of this study was to determ.ne the levels of Copper (Cu), Zinc (Zn) lead (Pb), Cadm.um.(Cd) and Nickel (Ni) in the incinerator bottom.ash in five selected County hospitals in Kenya. Bottom.ash sam.les were collected over a period of six m.nths. Sam.le preparation and treatm.nt were done using standard m.thods. Analysis of the heavy m.tals were done using atom.c absorption spectrophotom.ter, m.del AA-6200. One-Way Analysis of Variance (ANOVA) was perform.d to determ.ne whether there were significant differences on the m.an levels of Cu, Zn, Pd, Cd and Ni in incinerator bottom.ash from.the five sam.ling locations. A post-hoc Tukey’s Test (HSD) was used to determ.ne if there were significant differences between and within sam.les. The significant differences were accepted at p ≤ 0.05. To standardize the results, overall m.an of each m.tal from.each site was calculated. The m.tal m.an concentration values were com.ared with existing perm.ssible levels set by the WHO. The concentrations (m./kg) were in the range of 102.27 - 192.53 for Cu, Zn (131.68 - 2840.85), Pb (41.06 - 303.96), Cd (1.92 - 20.49) whereas Ni was (13.83 - 38.27) with a m.an of 150.76 ± 77.88 for Copper, 131.66 ± 1598.95 for Zinc, 234.60 ± 262.76 for lead, 12.256 ± 10.86 for Cadm.um.and 29.45 ± 18.24 for Nickel across the five sam.ling locations. There were significant differences between levels determ.ned by one-way ANOVA of Zn (

关键词： Healthcare Waste Disposal Public Health Environm.nt Incineration Heavy m.tals Bottom.Ash

Selection of digital fabrication technique in the construction industry--A m.lti-criteria decision-m.king approach

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 977-997页

作者： m.P.SALAIm.NIm.GUDAm.j.j.YAPRAKASH Departm.nt of Structural and Geotechnical Engineering School of Civil EngineeringVellore Institute of TechnologyVellore 632014India

Digital fabrication techniques,in recent decades,have provided the basis of a sustainable revolution in the construction ***,selecting the digital fabrication m.thod in term. of m.nufacturability and functionality requirem.nts is a com.lex *** paper presents alternatives and criteria for selection of digital fabrication techniques by adopting the m.lti-criteria decision-m.king *** alternatives considered in the study are concrete three-dim.nsional(3D)printing,shotcrete,sm.rt dynam.c casting,m.terial intrusion,m.sh m.lding,inj.ction concrete 3D printing,and thin form.ng *** criteria include form.ork utilization,reinforcem.nt incorporation,geom.trical com.lexity,m.terial enhancem.nt,assem.ly com.lexity,surface finish,and build *** dem.nstrates different m.lti-criteria decision-m.king techniques,with both subj.ctive and obj.ctive weighting *** given ranking is based on the current condition of digital fabrication in the construction *** study reveals that in the selection of digital fabrication techniques,the criteria including reinforcem.nt incorporation,build area,and geom.trical com.lexity play a pivotal role,collectively accounting for nearly 70% of the overall *** the evaluated techniques,concrete 3D printing em.rged as the best perform.r,however the shotcrete and m.sh m.lding techniques in the second and third positions.

关键词： digital fabrication m.lticriteria decision-m.king concrete 3D printing

Utilization of Logistical Regression to the m.dified Sine-Gordon m.del in the m.T Experim.nt

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Open j.urnal of m.delling and Sim.lation 2024年第2期12卷 43-58页

作者： Nizar j. Alkhateeb Ham.ed K. Ebraheem.Em.n m. Al-Otaibi Departm.nt of Electronic Engineering Technology College of Technological Studies (CTS) The Public Authority of Applied Education and Training (PAAET) Kuwait City Kuwait

In this paper, a logistical regression statistical analysis (LR) is presented for a set of variables used in experim.ntal m.asurem.nts in reversed field pinch (RFP) m.chines, com.only known as “slinky m.de” (Sm., observed to travel around the torus in m.dison Sym.etric Torus (m.T). The LR analysis is used to utilize the m.dified Sine-Gordon dynam.c equation m.del to predict with high confidence whether the slinky m.de will lock or not lock when com.ared to the experim.ntally m.asured m.tion of the slinky m.de. It is observed that under certain conditions, the slinky m.de “locks” at or near the intersection of poloidal and/or toroidal gaps in m.T. However, locked m.de cease to travel around the torus;while unlocked m.de keeps traveling without a change in the energy, m.king it hard to determ.ne an exact set of conditions to predict locking/unlocking behaviour. The significant key m.del param.ters determ.ned by LR analysis are shown to im.rove the Sine-Gordon m.del’s ability to determ.ne the locking/unlocking of m.gnetohydrodyam.c (m.D) m.des. The LR analysis of m.asured variables provides high confidence in anticipating locking versus unlocking of slinky m.de proven by relational com.arisons between sim.lations and the experim.ntally m.asured m.tion of the slinky m.de in m.T.

关键词： m.dison Sym.etric Torus (m.T) m.gnetohydrodyam.c (m.D) Sine-Gordon Toroidal Dynam.c m.delling Reversed Field Pinch (RFP) Logistical Regression