نتایج جستجو برای: boron rich mineral
تعداد نتایج: 239662 فیلتر نتایج به سال:
200 years of research with carbon-rich molecules have shaped the development of modern chemistry. Research pertaining to the chemistry of boron-rich species has historically trailed behind its more distinguished neighbor (carbon) in the periodic table. Notably, a potentially rich and, in many cases, unmatched field of coordination chemistry using boronrich clusters remains fundamentally underde...
An interesting feature of elemental boron and boron compounds is the occurrence of highly symmetric icosahedral clusters. The rich chemistry of boron is also dominated by three-dimensional cage structures. Despite its proximity to carbon in the periodic table, elemental boron clusters have been scarcely studied experimentally and their structures and chemical bonding have not been fully elucida...
almabulage complex is located in the north of asadabad city, northwestern hamedan province, in sanandaj-sirjan structural zone. the complex includes several types of low-grade metamorphosed rocks with various protoliths as well as two intrusion having different chemical compositions of synogranite and gabbro. the synogranite intrusion rock has perthite and granophyric co-growths textures and au...
This thesis is a theoretical study of configurational disorder in icosahedral boronrich solids, in particular boron carbide, including also the development of a methodological framework for treating configurational disorder in such materials, namely superatom-special quasirandom structure (SA-SQS). In terms of its practical implementations, the SA-SQS method is demonstrated to be capable of eff...
The effects of boron supplementation on blood and urinary minerals were studied in female college students--17 athletes and 11 sedentary controls--over a one-year period. The athletes had lower percent body fat and higher aerobic capacities than sedentary controls. Athletic subjects consumed more boron in their normal diets than sedentary subjects; all other dietary measures were similar betwee...
Young Valencia orange trees were grown for three years in large outdoor sand cultures on complete nutrient solu tions that varied differentially only in the amount of boron. Three rates of boron were applied to single-tree plots. The plots were replicated four times. No difference in tree size resulted from the differential treatments. Rather large differences in the boron content of the leaves...
Olivine is one of the major crystals in ultrabasic rocks of Piranshahr Ophiolitic Complex. This mineral occurs as anhedral with cracks and fractures. Commonly, olivine is altered to serpentine along the fractures and rims. In some cases, serpentine crosscut the olivine. According to BSE images and mineral chemistry studies of olivine, the secondary iron- rich olivines occur at the rim of primar...
The effect of divacancies on the stability, structural and electronic properties of carbon and boron nitride nanotubes is studied using the ab initio density functional method. V(B)B(N) is more stable in the boron-rich and less stable in the nitrogen-rich growth conditions, and V(N)N(B) is more stable in the nitrogen-rich than in the boron-rich conditions. We find that stoichiometric defects V(...
A synthetic methodology is developed to generate boron rich aromatic small molecules based on benzene and pyrene moieties for the detection of thermal neutrons. The prepared aromatic compounds have a relatively high boron content up to 7.4 wt%, which is important for application in neutron detection as (10)B (20% of natural abundance boron) has a large neutron induced reaction cross-section. Th...
Small boron clusters as individual species in the gas phase are reviewed. While the family of known boron compounds is rich and diverse, a large body of hitherto unknown chemistry of boron has been recently identified. Free boron clusters have been recently characterized using photoelectron spectroscopy and ab initio calculations, which have established the planar or quasi-planar shapes of smal...
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