نتایج جستجو برای: mineral surface

تعداد نتایج: 696324  

2007
Charles S. Zender

This proposal outlines a program of scientific research and educational development focused on mineral dust aerosol, atmospheric chemistry, and curricular use of satellite data. Mineral dust impacts the chemical composition of the atmosphere by providing a surface for heterogeneous chemistry, and for light scattering and absorption at photolytic wavelengths. We propose to assess the current and...

2004
Andrew R. Zimmerman Keith W. Goyne Jon Chorover Sridhar Komarneni Susan L. Brantley

The ‘‘mesopore protection hypothesis’’ [Chem. Geol. 114 (1994) 347; Geochim. Cosmochim. Acta 58 (1994) 1271] proposes that organic matter (OM) may be protected from enzymatic degradation by sequestration within mineral mesopores (2–50 nm diameter). This hypothesis is a leading, though controversial, theory in explaining both the preservation of some extremely labile OM compounds and observed co...

Journal: :iranian red crescent medical journal 0
marjan kouhnavard diabetes research center, endocrinology and metabolism clinical sciences institute, tehran university of medical sciences , tehran, ir iran; endocrinology and metabolism research center, endocrinology and metabolism research institute, tehran university of medical sciences, tehran , ir iran ensieh nasli esfahani diabetes research center, endocrinology and metabolism clinical sciences institute, tehran university of medical sciences , tehran, ir iran; endocrinology and metabolism research center, endocrinology and metabolism research institute, tehran university of medical sciences, tehran , ir iran mohammad montazeri young researchers club, babol branch, babol, ir iran seyed jafar hashemian diabetes research center, endocrinology and metabolism clinical sciences institute, tehran university of medical sciences , tehran, ir iran; endocrinology and metabolism research center, endocrinology and metabolism research institute, tehran university of medical sciences, tehran , ir iran; diabetes research center, endocrinology and metabolism clinical sciences institute, tehran university of medical sciences , tehran, ir iran. tel: +98-2188220037, fax: +98-2188220052 mitra mehrazma oncopathology research center, iran university of medical sciences, tehran, ir iran bagher larijani endocrinology and metabolism research center, endocrinology and metabolism research institute, tehran university of medical sciences, tehran , ir iran

background: revealing data on the role of vitamin d and calcium supplementation in bone health has led some to suggest that vitamin d and calcium treatment could also play a role in protecting bone against microgravity-induced mineral loss. objectives: the aim of the present study was to investigate the effects of vitamin d and calcium administration on microscopic and densitometric changes of ...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2007
Christopher Oze Dennis K Bird Scott Fendorf

Naturally occurring Cr(VI) has recently been reported in ground and surface waters. Rock strata rich in Cr(III)-bearing minerals, in particular chromite, are universally found in these areas that occur near convergent plate margins. Here we report experiments demonstrating accelerated dissolution of chromite and subsequent oxidation of Cr(III) to aqueous Cr(VI) in the presence of birnessite, a ...

2005
P. BALÁŽ

Base metal sulphides are an important source of various metals. They are typically intergrowth and due to the complex nature of their ores, the hydrometallurgical technique is the very convenient way of extracting the desired component. If it is possible to extract the metal from an ore selectively, the subsequent processing steps become less complicated. Mechanical activation seems to be a fav...

فاتحی مرجی, محمد , مرشدی, امین حسین , کوهساری, امیر حسین ,

Hardness of a mineral is one of its important physical properties and several methods have been presented for its determination. Mohs hardness determination is the most versatile method by which the mineral hardness is determined somewhat qualitatively with respect to another mineral and has no unit. In this paper, because of the need to measure the mineral hardness more accurately and give a m...

2010
YAN-JIE TANG HONG-FU ZHANG JI-FENG YING

Lithium isotopes have many advantageous characteristics as geochemical tracers for a wide range of geological processes, covering fluid/melt-mineral interactions from the Earth’s surface to the mantle. The latest developments in Li isotope geochemistry, in terms of measuring techniques, major geochemical reservoirs, the contrasting behaviors during near-surface weathering, and crust/ mantle cyc...

2013
Kaliyamoorthy Jayakumar Cheruth Abdul Jaleel

A study was carried out to understand the mineral constituent variations under cobalt treatment in Vigna mungo (L.) Hepper. The experiments were conducted in earthen pots and lined the inner surface with polythene sheet. Each pot contains 3 kg of air dried soil. Blackgram plants were raised in these pots containing soils amended with different concentrations of cobalt (0, 50, 100, 150, 200 and ...

2009
M. A. Velbel

Introduction: Orbiter and lander/rover studies of Mars' surface have identified and provided preliminary characterization of surficial materials including igne-ous and sedimentary rocks, possible volcaniclas-tic/pyroclastic rocks, and unconsolidated sediment. Some surfaces expose unaltered anhydrous silicates (militating against extensive interactions with water), but most results (including st...

2011
Daniel Gantenbein Joachim Schoelkopf Peter Matthews Patrick A.C. Gane

a r t i c l e i n f o Mineral particles are used in many industrial applications as fillers, in coatings, as ad-and absorbers or in catalysis. In these manifold fields the particle size and shape control the final performance and properties of the minerals. Much has been published using different techniques to describe the aspect ratio of platy particles. This study describes a simple method to...

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