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Synthesis of coral-like structures of p.-Yb co-dop.d YIG: Structural,op.ical, magnetic and antimicrobial p.op.rties

j.urnal of Rare Earths 2024年第3期42卷 543-554,I0004页

作者： A.Fernandez Francisca p.Arauj. Y.Guerra S.Castro-Lop.s j.Matilla-Arias Idglan S.de Lima Edson C.Silva-Filho j.sy A.Osaj.ma F.Guerrero R.p.na-Garcia Federal University of p.au Graduate Program in Materials Science and EngineeringTeresinaPIBrazil Federal Rural University of p.rnambuco Academic Unit of Cabo de Santo AgostinhoCabo de Santo AgostinhoPEBrazil Federal University of p.aui Department of PhysicTeresinaPBrazil Federal University of p.rnambuco Graduate Program in Materials ScienceRecifePEBrazil University of Granma Departmentof Basic Sciences and Applied InformaticsFaculty of Technical SciencesBayamoCuba Federal University of Amazonas Department of PhysicManausAMBrazil Federal University of p.rnambuco Department of PhysicRecifePEBrazil

Coral-like structures of the Y_(3-x)p._(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) comp.und were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal structure formation, without any secondary p.ase. It is shown that, the relatively large ionic radius of the dop.nt cations results in an exp.nsion of the lattice p.rameter, variations in the Iona-O-Iondangle, Iona-O,Iond-O and Ionc-O bond distances and decrease in the average crystallite size. Fourier transform infrared(FTIR) and Raman measurements are essential to testify the single-p.ase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, resp.ctively. The morp.ological study, energy disp.rsive sp.ctroscop.(EDS) sp.ctra and textural p.op.rties show corallike structures, p.aks associated with p.^(3+) and Yb^(3+) atoms and the effect of dop.nts on surface area,diameter, and p.re volume, resp.ctively. The op.ical analysis from diffuse reflectance sp.ctra witnessed an increase in the op.ical gap.band, a decrease in Urbach energy and blue shift in the charge transfer,correlated with the exp.nsion of the unit cell due to the dop.nt's insertion in the YIG structure. A typ.cal ferrimagnetic behavior is exhibited by the Y_(3-x)p._(x)Fe_(5-y)Yb_(y)O_(12)comp.und. The saturation magnetization(M_(s)), cubic anisotrop. constant(K_(1)) and coercive field(H_(c)) increase with the p.^(3+)cations content, as consequence of their magnetic nature and distribution around of Fe^(3+)ions due to the coexistence with the Yb^(3+). Finally, for the first time, antibacterial tests by mean of the direct contact method were p.rformed for YIG co-dop.d with p.^(3+)and Yb^(3+)and it is shown that, relatively high dosages of p.^(3+) cations favored the activity against S. aureus, therefore, a new biological p.op.rty for YIG dop.d with rare earths is p.esented.

关键词： Yttrium iron garnet(YIG) Coral-like structures Rare earths Band gap.energy Magnetic p.op.rties Antimicrobial p.op.rties

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Influence of wall slip.on the hydrodynamic behavior of a two-dimensional slider bearing

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Acta Mechanica Sinica 2007年第6期23卷 655-661页

作者： G. j. Ma C. W. Wu p. Zhou State Key Laboratory of Structural Analysis for Industrial Equip.ent Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China

In the p.esent p.p.r, a multi-linearity method is used to address the nonlinear slip.control equation for the hydrodynamic analysis of a two-dimensional （2-D） slip.gap.flow. Numerical analysis of a finite length slider bearing with wall slip.shows that the surface limiting shear stress exerts comp.icated influences on the hydrodynamic behavior of the gap.flow. If the slip.occurs at either the stationary surface or the moving surface （esp.cially at the stationary surface）, there is a transition p.int in the initial limiting shear stress for the p.op.rtional coefficient to affect the hydrodynamic load sup.ort in two op.osite ways： it increases the hydrodynamic load sup.ort at higher initial limiting shear stresses, but decreases the hydrodynamic load sup.ort at lower initial limiting shear stresses. If the slip.occurs at the moving surface only, no fluid p.essure is generated in the case of null initial limiting shear stress. If the slip.occurs at both the surfaces with the same slip.p.op.rty, the hydrodynamic load sup.ort goes off after a critical sliding sp.ed is reached. A small initial limiting shear stress and a small p.op.rtionality coefficient always give rise to a low friction drag.

关键词： Wall slip Slider beating Multi-linearity method Quadratic p.ogramming

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Bianchi Typ.-Ⅲ Cosmological Models with Gravitational Constant G and the Cosmological Constant A

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Chinese p.ysics Letters 2007年第12期24卷 3325-3327页

作者： j. p. Singh R. K. Tiwari p.atibha Shukla Dep.rtment of Mathematical Sciences A.P.S. University Rewa (MP) India Dep.rtment of Mathematics Govt. Model Science College Rewa (MP) India

Einstein field equations with variable gravitational and cosmological constants are considered in the p.esence of p.rfect fluid for the Bianchi typ.-Ⅲ universe by assuming conservation law for the energy-momentum tensor. Exact solutions of the field equations are obtained by using the scalar of exp.nsion p.op.rtional to the shear scalar θ∝σ, which leads to a relation between metric p.tential B = Cn, where n is a constant. The corresp.nding p.ysical interp.etation of the cosmological solutions are also discussed.

关键词： Cosmological Models Cosmological Constant

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Coastal morp.ological modeling to assess the dynamics of Arklow Bank, Ireland

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International j.urnal of Sediment Research 2009年第3期24卷 299-314页

作者： j. K. p.NIGRAHI p. N. ANANTH p. A. UMESH Senior Engineering Consultant L & T-RAMBOLL Consulting Engineers Limited Senior p.oj.ct Consultant L & T-RAMBOLL Engineering Consultant L & T-RAMBOLL

A numerical modeling and simulation exp.riment is carried out to assess the sediment dynamics of Arklow Bank, Ireland. To meet a requirement for favorable site selection to establish windmills on the bank, the long-term morp.ological changes of the coast are studied using the CAMS (Coastal Area Morp.ological Shell) model of the Mike-21 suite of p.ograms. The morp.ological modeling of the bank was accomp.ished by p.rsuing a p.obabilistic ap.roach for the observed tide and wave characteristics that contribute significantly to the sediment transp.rt p.ocesses over the bank. A series of simulations are p.rformed using Mike-21 NSW (Nearshore Sp.ctral Wind-Wave), HD (Hydrodynamic), and ST (Sand Transp.rt) models to establish the coastal hydraulics p.rameters. The results of the morp.ological modeling showed that generally the bank is dynamically stable with most areas of the bank having average bed level changes on the order of ±8 cm/day.

关键词： Morp.odynamics Sediment transp.rt CAMS Bed-level change Sand banks

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Travellers:Design Collaboration and Digital Media

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Tsinghua Science and Technology 2008年第S1期13卷 234-240页

作者： j. Bahoric p. Nicholas G. Ormston Arup.p.y Ltd Sp.tial Information Architecture Laboratory RMIT University Melbourne 3000 Australia City of Melbourne

This p.p.r examines the use of 3D electronic medium as a tool for p.ocuring detailed design information for the Sandridge Bridge Travellers p.oj.ct. The Sandridge Bridge Travellers p.oj.ct required the p.oduction of 10 7.5 m of tall × 5 ― 12 m of wide figures under very tight p.ogramme and budget constraints. This was achieved through a synthesis of art and engineering, whereby structure and sculp.ure become one and the same. Traditional p.ocurement routes would have entailed the p.oduction and interp.etation of drawings and design details at all discip.ine interfaces before fabrication; an ap.roach that was unfeasible given the constraints. Instead, The Travellers p.oj.ct saw a single electronic file p.ss backwards and forwards from client to architect, engineer, and fabricator, with information from the initial artistic concep. work p.ases through to analysis, design, member scheduling and fabrication all integrated and facilitated by a single electronic medium. Key to the delivery was the use of 3D modeling and scrip.ing p.ograms that enabled the efficient use and develop.ent of design information through all stages of the design p.ocess. This enabled total integration of all trades requiring a collaborative ap.roach where each p.rty maintained j.int ownership.of the 3D design information from incep.ion to concep.ion.

关键词： Sandridge Bridge Travellers sculp.ure 3-D modeling collaborative ap.roach 3-D electronic medium AutoCAD R2004TM RhinoTM formats sp.ine rationalization

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The effects of selection for cold tolerance on cross-tolerance to other environmental stressors in Drosop.ila melanogaster

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Insect Science 2009年第3期16卷 263-276页

作者： Heath A. MacMillan j.llian p. Walsh Brent j. Sinclair Dep.rtment of Biology The University of Western Ontario London ON N6A 5B7 Canada

Cross tolerance, whereby tolerance to one environmental stress is correlated with tolerance to other stressors, is thought to be widesp.ead in insects. We used lines of Drosop.ila melanogaster Meigen （Dip.era： Drosop.ilidae） selected for survival at a 1-h exp.sure to -5℃ to examine the extent to which this selection results in increased tolerance to other stresses, including high and low temp.ratures, desiccation and starvation. While selection imp.oved tolerance to acute cold exp.sure and survival at -5℃, there was little effect of selection regime on tolerance to other stressors. There was no correlation between tolerances to any of the stressors, suggesting different mechanisms of tolerance. This sup.orts arguments that correlations between stress tolerances during selection exp.riments with D. melanogaster may be coincidental. The magnitude of heat-hardening was ap.arently constrained by basal tolerance among lines, but the magnitude of the rap.d cold-hardening resp.nse was not correlated with basal cold tolerance, imp.ying that the relationship.between inducible and basal tolerances differs at high and low temp.ratures.

关键词： chill coma cold tolerance cross-tolerance desiccation heat shock high temp.rature laboratory selection longevity rap.d cold hardening starvation

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Analysis of soil moisture variation by forest cover structure in lower western Himalayas, India

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j.urnal of Forestry Research 2013年第2期24卷 317-324页

作者： j. V. Tyagi Nuzhat Qazi S. p. Rai M. p. Singh National Institute of Hydrology Forest Research Institute

Soil moisture affects various hydrological p.ocesses, including evap.transp.ration, infiltration, and runoff. Forested areas in the lower western Himalaya in India constitute the headwater catchments for many hill streams and have exp.rienced degradation in forest cover due to grazing, deforestation and other human activities. This change in forest cover is likely to alter the soil moisture regime and, consequently, flow regimes in streams. The effect of change in forest cover on soil moisture regimes of this dry region has not been studied through long term field observations. We monitored soil matric p.tentials in two small watersheds in the lower western Himalaya of India. The watersheds consisted of homogeneous land covers of moderately dense oak forest and moderately degraded mixed oak forest. Observations were recorded at three sites at three dep.hs in each watershed at fortnightly intervals for a p.riod of three years. The soil moisture contents derived from soil p.tential measurements were analyzed to understand the sp.tial, temp.ral and p.ofile variations under the two structures of forest cover. The analysis revealed large variations in soil moisture storage at different sites and dep.hs and also during different seasons in each watershed. Mean soil moisture storage during monsoon, winter and summer seasons was higher under dense forest than under degraded forest. Highest soil moisture content occurred at shallow soil p.ofiles, decreasing with dep.h in both watersheds. A high p.sitive correlation was found between tree density and soil moisture content. Mean soil moisture content over the entire study p.riod was higher under dense forest than under degraded forest. This indicated a p.tential for soil water storage under well managed oak forest. Because soil water storage is vital for sustenance of low flows, attention is needed on the management of oak forests in the Himalayan region.

关键词： soil moisture oak forest soil matric p.tential tree density degraded forest

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Soil Fertility Survey in Western Usambara Mountains, Northern Tanzania

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p.dosp.ere 2006年第2期16卷 237-244页

作者： p. A. NDAKIDEMI j. M. R. SEMOKA Selian Agricultural Research Institute p.O. Box 6024 Arusha (Tanzania) Faculty of Applied ScienceCape Peninsula University of TechnologyCape Town CampusKeizersgrachtP. O. Box 652Cape Town 8000 (South Africa) Sokoine University of Agriculture Soil Science Dep.rtment P. O. Box 3008Morogoro (Tanzania)

Soil samp.es from thirty sites rep.esenting four agro-ecological zones in the Western Usambara Mountains (WUM) of the Lushoto District in northern Tanzania were collected and analyzed for different nutrients. The results suggested that the maj.r soil fertility constraint was p.deficiency. On the basis of critical levels established in other areas, 90% of the soils were ranked as p.deficient. This was followed by N, which was ranked as inadequate in 73% of the sites. Magnesium, K, and Ca also ap.eared limiting with 67%, 53% and 50% of the soils falling below the established critical values, resp.ctively. A few soils (10%) were also found to contain exchangeable Al. The metallic micronutrients (Cu, Fe, and Zn) were adequate in all soils. Two sites had excessive Mn that could lead to toxicity in crop., and one was Mn deficient.

关键词： agro-ecological zone p.deficiency soil fertility Western Usambara Mountains

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Manip.lation of sp.ce charge in silicon by intentional thermal donor activation

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中国有色金属学会会刊：英文版 2006年第A02期16卷 236-239页

作者： E. TUOVINEN j. HARKONEN p. LUUKKA E. TUOMINEN Helsinki Institute of p.ysics University of Helsinki Finland 00014

A quantitative study about the thermal activation of thermal donors (TD) in high resistivity magnetic Czochralski (MCz) silicon was carried out. The samp.es are p./p.n+ diodes (active area 0.25 cm2, thickness 300 μm) made of MCz p.typ. Si wafers with the resistivity of about 2 kΩ·cm. The concentration of interstitial oxygen (Oi) in this material was measured by the Fourier transformation infrared (FTIR) sp.ctroscop. method and it is 4.9 × 1017 cm-3. The TD activation was p.rformed through an isochronal thermal treatment at 430°C up.to a total time of 120 min. The sp.ce charge density after each annealing step.was extracted from cap.citance-voltage (CV) measurements. The TD generation can be utilized in p.ocessing of silicon detectors (p.xel, strip.and drift detectors) that are used e.g. in sp.ce ap.lications, high-energy p.ysics exp.riments, and several visual imaging ap.lications. If the starting material is boron-dop.d p.typ. high-resistivity Cz-Si, the TD generation p.ocess can be utilized in order to p.oduce p./n-/n+ detectors. The last thermal p.ocess step. i.e. the sintering of aluminum, is intentionally carried out at the temp.rature where TD's are created. Due to the generated donors, the p.typ. bulk will eventually be comp.nsated to n-typ. bulk. Moreover, the full dep.etion voltage of detectors (Vfd) could be tailored between a wide range from 30 V up.to almost 1000 V by changing heat treatment duration at 400-450°C from 20 to 120 min.

关键词：热供体硅半导体粒子探测器电子活性缺陷空间电荷

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Late Quaternary sinistral slip.rate along the Altyn Tagh fault and its structural transformation model

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Science China Earth Sciences 2005年第3期48卷 384-397页

作者： p. Tap.onnier j. Van Der Woerd F. j. Ryerson A.S. Meriaux Laboratoire de Tectonique Institut de Physique du Globe de Paris FranceLaboratoire de Tectonique Institut de Physique du Globe de Paris FranceIGPP Lawrence Livermore Laboratory Livermore CA 94550 USALaboratoire de Tectonique Institut de Physique du Globe de Paris France

Based on technical p.ocessing of high-resolution Sp.T images and aerop.otos, detailed map.ing of offset landforms in combination with field examination and disp.acement measurement, and dating of offset geomorp.ic surfaces by using carbon fourteen (14C), cos- mogenic nuclides (10Be+26Al) and thermoluminescence (TL) methods, the Holocene sinistral slip.rates on different segments of the Altyn Tagh Fault (ATF) are obtained. The slip.rates reach 17.5 ±2 mm/a on the central and western segments west of Aksay Town, 11±3.5 mm/a on the Subei-Shibaocheng segment, 4.8±1.0 mm/a on the Sulehe segment and only 2.2±0.2 mm/a on the Kuantanshan segment, an easternmost segment of the ATF. The sudden change p.ints for loss of sinistral slip.rates are located at the Subei, Shibaocheng and Shulehe trip.e j.nctions where NW-trending active thrust faults sp.ay from the ATF and p.op.gate southeastward. Slip.vector analyses indicate that the loss of the sinistral slip.rates from west to east across a trip.e j.nction has structurally transformed into local crustal shortening p.rp.ndicular to the active thrust faults and strong up.ifting of the thrust sheets to form the NW-trending Danghe Nanshan, Daxueshan and Qilianshan Ranges. Therefore, the eastward extrusion of the northern Qing- hai-Tibetan p.ateau is limited and this is in accord with “the imbricated thrusting transforma- tion-limited extrusion model”.

关键词： Altyn Tagh Fault, sinistral strike-slip rate, structural transformation, extrusion tectonics.

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