نتایج جستجو برای: earth cation

تعداد نتایج: 148521  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - پژوهشکده علوم 1388

heteropoly acids (hpa) and their salts have advantages as catalysts which make them both economically and environmentally attractive, strong br?nsted acidity, exhibiting fast reversible multi-electron redox transformations under rather mild conditions, very high solubility in polar solvents, fairly high thermal stability in the solid states, and efficient oxidizing ability, so that they are imp...

Journal: :Minerals 2023

China, Vietnam, Brazil, and Russia have the largest deposits of rare earths. However, in recent works, occurrence light earth elements has been demonstrated an exhalative sedimentary type mineral (SEDEX) Mexico, with adequate Ce Nd contents. Additionally, it is this that used to study cation exchange capacity non-metallic minerals organic materials, such as bentonite, diatomite, eggshell. To ca...

2009
Michael D. Richardson R.Keith Warner Nancy A. Wolf Greg C. Jones

A field study was designed to study several inorganic soil amendments as a substitute for sand in the top-dressing of an aerified, sandbased putting green. Several forms of natural zeolites, calcined clays, and diatomaceous earth were blended with sand and used to backfill aerification holes on a sand-based putting green. Several of these amendments enhanced turfgrass recovery and quality in th...

2007
O. CorsoN

In order to better understand magma evolution at depth in the Earth, partition coefficients between low-Ca pyroxene and melt have been experimentally determined at 15 and 20 kbar. Results indicate that partitioning of Sc, Yb, and Ca is little afected by pressure but Al partitioning increases significantly. We conclude that the unique dependence of Al partitioning on pressure results from the st...

2010
Koichiro Umemoto Renata M. Wentzcovitch

We present a systematic density-functional study of phase relations in three 4d-transition-metal sesquioxides: Y2O3, Rh2O3, and In2O3. Y2O3 and In2O3 undergo pressure-induced transitions to phases with larger cation coordination number (from 6 to 7) at low pressures. However, this does not occur in Rh2O3 at least up to *300 GPa. This cannot be explained by usual arguments based on ionic-radii r...

Journal: :Dalton transactions 2006
De-Liang Long Oliver Brücher Carsten Streb Leroy Cronin

A range of complexes based on the high-nuclearity [W36] isopolyoxotungstate cluster, [H12W36O120]12-, with a triangular topology has been isolated by using the organic cation, protonated triethanolamine. In analogy to an 18-crown-6 crown ether with six oxygen donors on a ring, the cluster can form alkali and alkaline earth metal complexes [M within W36] (M = K+, Rb+, Cs+, NH4+, Sr2+ and Ba2+, 1...

Journal: :Journal of the American Chemical Society 2004
Anja-Verena Mudring John D Corbett

Theoretical reasons for metallic behavior among diverse Zintl phases have generally not been pursued at an advanced level. Here, the electronic structure of Ca5Ge3 (Cr5B3 type), which can be formulated (Ca+2)5(Ge2-6)Ge-4 in oxidation states, has been explored comparatively by means of semiempirical and first-principles density functional methods. The FP-APW calculations show that alkaline-earth...

2013
Anthony M. T. Bell C. Michael B. Henderson

The fresnoite-type compound Sr2TiO(Si2O7), distrontium oxidotitanium disilicate, has been prepared by high-temperature solid-state synthesis. The results of a Rietveld refinement study, based on high-resolution synchrotron X-ray powder diffraction data, show that the title compound crystallizes in the space group P4bm and adopts the structure of other fresnoite-type mineral samples with general...

2004
B. Janoszka U. Błaszczyk D. Bodzek

An analytical scheme developed for determination of PAH and aminoazaarenes has been applied to the analysis of aza-PAH formed in thermally treated high-protein food. The clean-up procedure, which was based on tandem solid-phase extraction (SPE) on columns filled with Extrelut diatomaceous earth and with cation exchanger (propylsulphonic acid, PRS), enabled selective isolation of carcinogenic az...

2003

Over the past fiscal year, our investigations of phase composition, cation disorder, and texture quality of coated-conductor embodiments by Raman microscopy methods have been conducted with three objectives in mind: (1) developing an improved understanding of the methodology itself (e.g., in terms of how Raman excitation/configuration parameters influence the observations), (2) investigating sy...

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