136 research outputs found

    Isotopic and Microstructural Analyses of Opaque Mineral Assemblages and Their Alteration Products Hosted in a Refractory Inclusion

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    Calcium-aluminum-rich inclusions (CAIs) hosted in primitive meteorites are the oldest solids formed in the Solar System. Some CAIs contain metal nuggets that are complex assemblages of Fe-Ni alloys, along with rare ultra-refractory metals such as platinum group elements (PGEs), and their alteration products such as magnetite, sulfides, and phosphates. Three possible mechanisms proposed to explain the origin of these metal nuggets include condensation in circumstellar settings, condensation in the solar nebula within the CAI-forming region, or crystallization from immiscible metal-silicate melt. However, secondary alteration processes may have also affected some of these assemblages. Additionally, similar metal assemblages observed in chondrules and chondritic matrix indicate that all of these metal nuggets could share common high-temperature origins. These metal assemblages record early Solar System conditions that are reflected in their distinctive chemical composition, mineralogy and microstructures. Here we report a detailed mineralogical, microstructural and oxygen isotopic study of one such metal assemblage hosted in a CAI to understand the physical and chemical settings in which it formed

    Determination of Interface Atomic Structure and Its Impact on Spin Transport Using Z-Contrast Microscopy and Density-Functional Theory

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    We combine Z-contrast scanning transmission electron microscopy with density-functional-theory calculations to determine the atomic structure of the Fe/AlGaAs interface in spin-polarized light-emitting diodes. A 44% increase in spin-injection efficiency occurs after a low-temperature anneal, which produces an ordered, coherent interface consisting of a single atomic plane of alternating Fe and As atoms. First-principles transport calculations indicate that the increase in spin-injection efficiency is due to the abruptness and coherency of the annealed interface.Comment: 16 pages (including cover), 4 figure

    Analisis Pengelolaan Agroforestry Dan Kontribusinya Terhadap Perekonomian Masyarakat

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    Agroforestry is a form of community forestry. Agroforestry management related to the optimization of land use for their daily livesof farmers and in order to conserve natural resources. This study aimed to determine the contribution of agroforestry for house hold incomes in Sitaratoit and Lobulayan Village, Tapanuli Selatan District. The results showed that total community income was Rp. 875.900.000,- per year with details incomes from agroforestry was Rp. 597.000.000,- and income from the outside the utilization of agroforestry products contributed Rp.300.900.000,-. Contribution of agroforestry products for people's income is 63% of total income. Income community outside ofagroforestry such as farmer, trader, public civil servant, pensioner and entrepreneur contribute 37% of total income. This means that agroforestry contributed greatly to the house hold income

    Faktor-faktor yang Mempengaruhi Perilaku Ibu Nifas dalam Mengkonsumsi Tuo Nifarö di Kecamatan Lotu Kabupaten Nias Utara

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    Tuo nifarö istypicalofNiasdrink that contains alcohol that resulted from distillation of cocoa. Tuo nifarö can be utilizedfor many purposes, one of them usedfor post-partum period treatment. The aim of this research is to knowing the determinant of post-partum mother's behavior who consumedtuonfaroin Lotu, District of North Nias. This kind of researchis descriptivequantitative andqualitative approachto completethe required datawith a sample of 52 people. The resultsof research onthe characteristics ofrespondents,59.6% were25-35years and61.5% of respondentshavea loweducation level. 61.5% of post-partummothers have the moderate trust levelson benefit ofconsumingtuo nifarö. In terms ofnormativebelief, theconsumptionof alcoholic beveragessuch astuo nifarö for post-partum mothers is affected bythe role offamiliesand communitiesthatinfluence the post-partum mothersto act. Attitudetowardconsumption of tuo nifarö 53.8% wereatmoderatelevels. In terms ofaction, 55.8% of respondentsconsumealcoholic beveragespostpartum, where82.8% had a loweducational level, 48.3% have the confidenceandgood judgment, and 58.6% at a moderate level, 100% supportedbyfamiliesand89.7% are supportedby the community. 72.4% of respondentshadconsumedblack beer as a substitutefor various reasons. This occasion should be maintained with regard to alcohol content, and health workers need to explore the benefits of taking tuo nifar

    FIB-TEM Investigations of Fe-NI-Sulfides in the CI Chondrites Alais and Orgueil

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    The CI chondrites are primitive meteorites with bulk compositions matching the solar photosphere for all but the lightest elements. They have been extensively aqueously altered, and are composed primarily of fine-grained phyllosilicate matrix material which is host to carbonates, sulfates, sulfides, and minor amounts of olivine and pyroxene. The alteration, while extensive, is heterogeneous. For example, CI-chondrite cubanite and carbonate grains differ on mm to sub-mm scales, demonstrating multiple aqueous episodes. CI-chondrite variability is also evidenced by degree of brecciation, abundance and size of coarse-grained phyllosilicates, olivine and pyroxene abundance, as well as Ni-content and size of sulfide grains. Our previous work revealed Orgueil sulfide grains with variable Ni-contents, metal:S ratios, crystal structures and textures. We continue to explore the variability of CI-chondrite pyrrhotite (Po, (FeNi)1-xS) and pentlandite (Pn, (Fe,Ni)9S8) grains. We investigate the microstructure of sulfides within and among CI-chondrite meteorites in order to place constraints on the conditions under which they formed
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