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Co-,fe-,Ni-doped and co-doped rutile GeO_(2):insights from ab-initio calculations

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Communications in Theoretical Physics 2022年第4期74卷 113-126页

作者： R essajai e Salmani M Bghour A Labrag F Goumrhar M Fahoume H ez-Zahraouy Materials and Subatomic Physics Laboratory Faculty of SciencesIbn Tofail UniversityKenitraMorocco Group of Semiconductors and environmental Sensor Technologies-energy Research Center Faculty of ScienceMohammed V UniversityB.P.1014RabatMorocco Laboratory of Condensed Matter and Interdisciplinary Sciences Department of PhysicsFaculty of SciencesMohammed V UniversityP.O.Box 1014RabatMorocco equipe des Matériaux Supraconducteursàhaute température critique Department of PhysicsIbn Zohr UniversityFaculty of SciencesBP:8106AgadirMorocco Faculty of Applied Sciences Route Nationale N°10 citéAzrouAit MelloulIbn Zohr UniversityAit MelloulIbn Zohr UniversityMorocco Higher school of education and Training of el Jadida(eSeF) Chouaib Doukkali UniversityEl Jadida 24000Morocco Laboratory of Physics of High energy Modeling&Simulations(LPHE-MS)Faculty of SciencesMohammed V University of RabatIbn BatoutaB.P.1014 RabatMorocco Laboratoire des Sciences de l’Ingénieur pour l’energie Ecole Nationale des Sciences Appliquées d’El Jadida(ENSA-J)BP 1166EL Jadida Plateau24002Morocco

Rutile germanium oxide(rutile GeO_(2)),a semiconductor,can act as a half-metallic compound and is a promising material for spintronic and optoelectronic *** were performed using the korringa–kohn–Rostoker(kkR)approach and the coherent potential approximation(CPA),which were further combined with two approximations,the local density approximation(LDA)and the self-interaction corrected LDA approximation(LDA-SIC),to study the electronic structure of bulk rutile GeO_(2) doped and co-doped with three transition-metal impurities:fe,Co,and *** doping value was set to 10%,while the co-doping level was set to 5%for each *** main findings of this work are:(1)a direct ultrawide bandgap of4.80 eV is observed and the rutile GeO_(2) exhibits an N-type semiconducting property.(2)Doped and co-doped GeO_(2) acquire a magnetic behavior and exhibit half-metallicity.(3)The mechanism responsible for these properties is also studied.(4)The critical temperature can reach 334 k when GeO_(2) is doped with fe,while it rises to 398 k when it is co-doped with fe and Co.(5)The spin polarization can be improved by *** can be inferred that rutile GeO_(2) doped or codoped with(Co,fe)transition metals can be considered to be potential candidates for spintronic and optoelectronic applications.

关键词： LDA approximation spintronic Curie temperature spin polarization LDA-SIC approximation rutile germanium oxide

Spatial Variations of Particle-Bound Trace Metals in Ambient Air of Selected Niger Delta Communities of Rivers State, Nigeria

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Journal of environmental Protection 2013年第12期4卷 1502-1509页

作者： Godson R. e. e. Ana Mynepalli k. C. Sridhar Jerome Nriagu Department of environmental Health Sciences Faculty of Public Health University of Ibadan Ibadan Nigeria Department of environmental Health Sciences School of Public Health University of Michigan Ann Arbor USA

The objective of this study was to determine the spatial variation of particle-bound heavy metals in two communities with different industrial status in Nigeria’s Niger Delta Area. Fourteen ambient respirable particulate matter (PM10) samples 7 each from eleme (highly industrialized) and Ahoada east (less industrialized) communities were collected according to standard methods using Anderson High volume sampler. Samples were analyzed for trace metals including fe, Zn, Ni, Cd, and Pb using Atomic Absorption Spectrophotometer. Data were analyzed using descriptive statistics, Man Whitney U test and Spearman Rank Correlation all at P 10 levels were 1.83 times higher at eleme than Ahoada east (P 0.05) and all the values were higher than both the USePA and WHO limits. At eleme spatial variation of PM10 was in the following order: APe5 > APe3 > APe7 > APe1 > APe4 > APe6 > APe2. fe, Zn and Cd were higher at eleme than Ahoada east and the eC/WHO values. Pb was poorly correlated with PM10 (r2 = 0.0819, P > 0.05) at eleme. Communities with higher industrial presence in the Niger Delta are more exposed to particulate burden. Routine monitoring and strict adherence to regulatory limits must be enforced.

关键词： Industrial Pollution Particulate Matter Trace Metals Spatial Variation Niger Delta Communities

Micromagnetic Structure of Co-Rich Amorphous Microwires

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Journal of Materials Science & Technology 2000年第2期16卷 183-185页

作者： e.e.Shalyguina and L.M.Bekoeva (Physical Faculty, Moscow State University, 119899, Moscow, Russia) kyung-Ho Shin (korea Institute of Science & Technology , P.O. Box 131, Cheongryang, Seoul 130-650, korea) Physical Faculty Moscow State University 119899 Moscow Russian Federation korea Institute of Science and Technology Cheongryang Seoul 130-650 P.O. Box 131 South Korea

Results on the magneto-optical investigation of near-surface micromagnetic structure (MMS) of Co69fe4Si12B15 amorphous wires 10～50 μm in diameter are presented. The wires were prepared by the rapid solidification technique. The magnetic field H was applied along or perpendicular to the wire length. By scanning the light spot of 1 μm-diameter along the wire length, distributions of magnetization components (both parallel and perpendicular to the applied magnetic field) and also local hysteresis characteristics of the wires were measured. It was experimentally established that owing to the compressive stresses from quenching coupled with negative magnetostriction of Co-rich amorphous materials, the examined microwires have a circumferential magnetic anisotropy. In consequence, there are the near-surface alternate left- and right-handled circular domains in these samples. The dependencies of the circular domain width on the wire diameter and length were found. It was discovered that in the axial magnetic field local hysteresis loops are unhysteretic. It was proved that in this case the dominant mechanism of the wire magnetization reversal is rotation of local magnetization vectors in circular domains.

关键词： Rich Micromagnetic Structure of Co-Rich Amorphous Microwires MMS

Assessing the utility of dissolved organic matter photoreactivity as a predictor of in situ methylmercury concentration

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Journal of environmental Sciences 2018年第6期30卷 160-168页

作者： Sara J.klapstein Susan e.Ziegler David A.Risk Nelson J.O'Driscoll environmental Science Program Memorial University of Newfoundland Department of earth Sciences St. Francis Xavier University Department of earth and environmental Science Acadia University

Methylmercury（MeHg） bioaccumulation is a growing concern in ecosystems worldwide. The absorption of solar radiation by dissolved organic matter（DOM） and other photoreactive ligands can convert MeHg into less toxic forms of mercury through photodemethylation. In this study, spectral changes and photoreactivity of DOM were measured to assess the potential to control photoreactions and predict in situ MeHg concentration. Water samples collected from a series of lakes in southwestern Nova Scotia in June, August, and September were exposed to controlled ultraviolet-A（UV-A） radiation for up to 24 hr. Dissolved organic matter photoreactivity, measured as the loss of absorbance at 350 nm at constant UV-A irradiation, was positively dependent on the initial DOM concentration in lake waters（r^2=0.94）. This relationship was consistent over time with both DOM concentration and photoreactivity increasing from summer into fall across lakes. Lake in situ MeHg concentration was positively correlated with DOM concentration and likely catchment transport in June（r = 0.77） but not the other sampling months. Despite a consistent seasonal variation in both DOM and fe, and their respective correlations with MeHg, no discernable seasonal trend in MeHg was observed. However, a 3-year dataset from the 6 study lakes revealed a positive correlation between DOM concentration and both fe（r = 0.91） and MeHg concentrations（r = 0.51） suggesting a more dominant landscape mobility control on *** DOM-MeHg relationships observed in these lakes highlights the need to examine DOM photoreactivity controls on MeHg transport and availability in natural waters particularly given future climate perturbations.

关键词： Methylmercury Dissolved organic carbon Photoreactions kejimkujik National Park Freshwater lakes

extensional collapse of the Gondwana orogen: evidence from Cambrian mafic magmatism in the Trivandrum Block, southern India

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Geoscience Frontiers 2019年第1期10卷 263-284页

作者： Qiong-Yan Yang Sohini Ganguly e.Shaji Yunpeng Dong V.Nanda-kumar school of earth Science and Resources China University of Geosciences Department of earth Science Goa University Department of Geology University of Kerala State key Laboratory of Continental Dynamics Department of Geology Northwest University National Center for earth Science Studies Akkulam Trivandrum India

The assembly of Late Neoproterozoice Cambrian supercontinent Gondwana involved prolonged subduction and accretion generating arc magmatic and accretionary complexes, culminating in collision and formation of high grade metamorphic orogens. Here we report evidence for mafic magmatism associated with post-collisional extension from a suite of gabbroic rocks in the Trivandrum Block of southern Indian Gondwana fragment. Our petrological and geochemical data on these gabbroic suite show that they are analogous to high fe tholeiitic basalts with evolution of the parental melts dominantly controlled by fractional crystallization. They display enrichment of LILe and LRee and depletion of HFSe with negative anomalies at Zre Hf and Ti corresponding to subduction zone magmatic regime. The tectonic affinity of the gabbros coupled with their geochemical features endorse a heterogeneous mantle source with collective melt contributions from sub-slab asthenospheric mantle upwelling through slab break-off and arc-related metasomatized mantle wedge, with magma emplacement in subduction to post-collisional intraplate settings. The high Nb contents and positive Nbe Ta anomalies of the rocks are attributed to inflow of asthenospheric melts containing ancient recycled subducted slab components and/or fusion of subducted slab materials owing to upwelling of hot asthenosphere. Zircon grains from the gabbros show magmatic crystallization texture with low U and Pb content. The LA-ICPMS analyses show ^(206) Pb/^(238) U mean ages in the range of 507-494 Ma suggesting Cambrian mafic magmatism. The post-collisional mafic magmatism identified in our study provides new insights into mantle dynamics during the waning stage of the birth of a supercontinent.

关键词： Mafic dykes Geochemistry Zircon Ue Pb geochronology Post-collisional extension Gondwana supercontinent

Technosols Made of Wastes to Improve Physico-Chemical Characteristics of a Copper Mine Soil

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Pedosphere 2013年第1期23卷 1-9页

作者： V.ASeNSIO F.A.VeGA M.L.ANDRADe e.F.COVeLO Department de Bioloxía Vexetal e Ciencia do Solo Facultade de Bioloxia Universidade de VigoLagoas Marcosende 36310 Vigo Pontevedra (Spain)

Mine tailing soils created from the copper extraction in Touro Mine （Northwest Spain） are very degraded both physically and chemically. Three plots in this mine tailing were amended with Technosols in different proportions in each one to know if this mixture improved the physico-chemical characteristics of the mine soil and contaminated it with heavy metals. The Technosols were made of organic wastes, including mussel residues, wood fragments, sewage sludges and paper mill ashes. An unamended area was used as a control soil. Pseudototal and diethylenetriaminepentaacetic acid （DTPA）-extractable contents of A1, Cr, Cu, fe, Mn, Ni, Pb and Zn were determined in soil samples. The untreated soil had significant limitations for vegetation growth. All the Technosols improved the properties of the mine soil by increasing organic carbon and pH value, but they added Ni, Pb or Zn to the soil. It is advisable to check whether the heavy metal concentrations of the wastes are hazardous or not before adding to soils. It is also necessary to study the effect of these wastes over time and in more areas to conclude if they are actually favourable to restore degraded mine soils.

关键词： heavy metals mine tailing vegetation growth waste amendment

Copper Delivery by the Copper Chaperone for Chloroplast and Cytosolic Copper/Zinc- Superoxide Dismutases： Regulation and Unexpected Phenotypes in an Arabidopsis Mutant

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Molecular Plant 2009年第6期2卷 1336-1350页

作者： Christopher M. Cohu Salah e. Abdel-Ghany kathryn A. Gogolin Reynolds Alexander M. Onofrio Jared R. Bodecker Jeffrey A. kimbrel krishna k. Niyogi Marinus Pilon Biology Department Colorado State University Fort Collins CO 80523-1878 USA Department of Plant and Microbial Biology University of California Berkeley CA 94720-3102 USA

Copper （Cu） is an important mineral nutrient found in chloroplasts as a cofactor associated with plastocyanin and Cu/Zn superoxide dismutase （Cu/ZnSOD）. Superoxide dismutases are metallo-enzymes found in most oxygenic organisms with proposed roles in reducing oxidative stress. Several recent studies in Arabidopsis have shown that microRNAs and a SQUAMOSA promoter binding protein-like7 （SPL7） transcription factor function to down-regulate the expression of many Cu-proteins, including Cu/ZnSOD in both plastids and the cytosol, during growth on low Cu. Plants contain the Cu Chaperone for SOD （CCS） that delivers Cu to Cu/ZnSODs, and, in Arabidopsis, both cytosolic and plastidic CCS versions are encoded by one gene. In this study, we demonstrate that Arabiclopsis CCS transcript levels are regulated by Cu, mediated by microRNA 398 that was not previously predicted to target CCS. The microRNA target site is conserved in CCS of Oryza sativa. The data suggest that Cu-regulated microRNAs may have more mRNA targets than was previously predicted. A CCS null mutant has no measurable SOD activity in the chloroplast and cytosol, indicating an absolute requirement for CCS. When the CCS null mutant was grown on high Cu media, it lacked both fe superoxide dismutase （feSOD） and Cu/ZnSOD activity. However, this did not lead to a visual phenotype and no photosynthetic deficiencies were detected, even after high light stress. These results indicate that Cu/ZnSOD is not a pivotal component of the photosynthetic anti-oxidant system during growth in laboratory conditions.

关键词： Chloroplast photosynthesis copper homeostasis superoxide dismutase microRNA.

Modelling a Skin-Pass Rolling Process by Means of Data Mining Techniques and Finite element Method

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Journal of Iron and Steel Research International 2012年第5期19卷 43-49页

作者： R escribano R Lostado F J Martínez-de-Pisón A Pernía e Vergara eDMANS Group Mechanical Engineering Department of the University of La Rioja Logroo 26004 La Rioja Spain

An experience is presented using the finite element method （feM） and data mining （DM） techniques to develop models that can be used to optimieze the skin-pass rolling process based on its operating conditions. A fe model based on a real skin-pass process is built and validated. Based on this model, a group of fe models is simulated with different adjustment parameters and with different materials for the sheet; both variables are chosen from pre-set ranges, From all fe model simulations, a database is generated; this database is made up of the above mentioned adjustment parameters, sheet properties and the variables of the process arising from the simulation of the model. Various types of data mining algorithms are used to develop predictive models for each of the variables of the *** best predictive models can be used to predict experimentally hard-to-measure variables （internal stresses, internal straine, etc.） which are useful in the optimal design of the process or to be applied in real time control systems of a skin-pass process in -plant.

关键词： skin-pass rolling predictive model finite element method data mining

Coat color and its effect on preference for the scent marks of opposite-sex conspecifics in the meadow vole Microtus pennsylvanicus

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Current Zoology 2012年第2期58卷 221-227页

作者： Ashlee A. VAUGHN Antedra A. FINGeR Porshia e. GIBBS mich.e. H. feRkIN Department of Biological Sciences The University of Memphis Memphis TN 38152 USA

Many mammal species can distinguish between opposite-sex conspecifics that differ in a certain trait. In that coat coloration is associated with differences in physiological and behavioral traits, coat color may affect the attractiveness of odor cues produced by conspecifics. Individuals may be able to respond preferentially to conspecifics with a particular coat color. In the present study, we test the hypothesis that scent marks of brown and blond voles differ in their attractiveness to male and fe- male conspecifics. Male voles and brown females did not discriminate between blond- and brown-coated opposite-sex con- specifics suggesting that they are neither selecting potential mates dissociatively nor associatively. However, blond females be- haved as if the scent marks of blond males were more attractive than were the scent marks of brown males. Our data suggest that blond females who are already conspicuous to predators, may select blond males as mates because they do not appreciably in- crease the risk of detection to predators, particularly avian predators. Moreover, because these conspicuous males have survived to mate they may have good genes that reflect their relatively higher quality

关键词： Coat color Meadow vole Odor preference Olfactory communication Scent mark