نتایج جستجو برای: mineral transformation
تعداد نتایج: 286226 فیلتر نتایج به سال:
Anatase-to-rutile phase transformation was studied in milled and unmilled samples. Ball milling was carried out in two types of ball mills, planetary and tumbler, with a ball-to-powder ratio of 40:1 over 2-48 hours. First, the unmilled samples were heated in the furnace at various temperatures for different periods of time. The results revealed that the anatase-to-rutile transformation comple...
The formation conditions, solubility and stability of monohydrocalcite (MHC, CaCO3·H2O), as well as sorption behaviors of toxic anions on MHC, are reviewed to evaluate MHC as a remediation material for hazardous oxyanions. MHC is a rare mineral in geological settings that occurs in recent sediments in saline lakes. Water temperature does not seem to be an important factor for MHC formation. The...
plant tissue culture techniques are used as basic requirement of common plant transformation systems. in most cases of plant transformation, a reproducible regeneration protocol is the limiting step due to long time lasting, specialized facilities and well experienced persons. furthermore, tissue culture procedures induce somaclonal variation among regenerated transgenic plants. therefore, rece...
Mercury (Hg) is a toxic heavy metal that poses significant environmental and human health risks. Soils and sediments, where Hg can exist as the Hg sulfide mineral metacinnabar (β-HgS), represent major Hg reservoirs in aquatic environments. Metacinnabar has historically been considered a sink for Hg in all but severely acidic environments, and thus disregarded as a potential source of Hg back to...
We have studied the syn-kinematic very low-grade metamorphism in a polyphase Variscan deformed region using X-ray diffraction techniques. Two phases of regional metamorphism are related to their respective episodes of penetrative deformation in the southern Central Iberian Zone. The data obtained suggest that the rocks did not reach metamorphic equilibrium, but strain favoured the progress of m...
Numerous works have shown that the mineral composition of plants is influenced by the element levels in the ground, by fertilization methods, by the physiological aspects typical of the species from which they are produced, as well as by the technological conditions of production when it deals of transformation alimentary products. Therefore the multielement content method represents a valid to...
Magnetotactic bacteria are aquatic microorganisms that intracellularly mineralize ferrimagnetic nanoparticles enabling the cells to align with the geomagnetic field. The bacteria produce a magnetic mineral of species-specific phase (magnetite Fe(II)Fe(III)2O4 or greigite Fe(II)Fe(III)2S4), size, morphology and particle assembly. Several species produce crystals of unusual elongated particle sha...
Underground coal gasification (UCG) is a promising option for the recovery of low-rank and inaccessible coal resources. Detailed mineralogical information is essential to understand underground reaction conditions far from the surface and optimize the operation parameters during the UCG process. It is also significant in identifying the environmental effects of UCG residue. In this paper, with ...
background: the purpose of this study was to evaluate long-term changes in bone density profile among survivors of childhood acute lymphoblastic leukemia. patients and methods: this was a 5 year prospective study comprised of thirty-one survivors of childhood acute lymphoblastic leukemia with a mean age of 11.8 (4.6) years, who completed therapy at least 1 year previously (according to the all-...
A new acidophilic iron-oxidizing strain (C25) belonging to the novel genus Acidithrix was isolated from pelagic iron-rich aggregates ('iron snow') collected below the redoxcline of an acidic lignite mine lake. Strain C25 catalysed the oxidation of ferrous iron [Fe(II)] under oxic conditions at 25 °C at a rate of 3.8 mM Fe(II) day(-1) in synthetic medium and 3.0 mM Fe(II) day(-1) in sterilized l...
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