نتایج جستجو برای: boron
تعداد نتایج: 18025 فیلتر نتایج به سال:
Various types of zero, one, and two-dimensional boron nanomaterials such as nanoclusters, nanowires, nanotubes, nanobelts, nanoribbons, nanosheets, and monolayer crystalline sheets named borophene have been experimentally synthesized and identified in the last 20 years. Owing to their low dimensionality, boron nanomaterials have different bonding configurations from those of three-dimensional b...
Boron is a trace mineral which is found in highest amounts in fruits, vegetables, nuts, and legumes. Although it has not been demonstrated unequivocally to be an essential nutrient for humans, increasing evidence indicates that boron deficiency and supplementation exert measurable biological effects. Boron has been shown to impact mineral metabolism, brain function and performance, and selected...
We use scanning tunneling microscopy and X-ray spectroscopy to characterize the atomic and electronic structure of boron-doped and nitrogen-doped graphene created by chemical vapor deposition on copper substrates. Microscopic measurements show that boron, like nitrogen, incorporates into the carbon lattice primarily in the graphitic form and contributes ~0.5 carriers into the graphene sheet per...
Lettuce, which is being grown in ever increasing quantities, suffers from a number of nutritional disorders which have been the subject of considerable speculation and study. Much of the difficulty with lettuce is evidently the result of the type of forcinig culture which is used to obtain the most firm and succulent heads. Among the micro-nutrient elements, boron has been given considerable at...
Reversible, heterolytic addition of H2 across an iron-boron bond in a ferraboratrane with formal hydride transfer to the boron gives iron-borohydrido-hydride complexes. These compounds catalyze the hydrogenation of alkenes and alkynes to the respective alkanes. Notably, the boron is capable of acting as a shuttle for hydride transfer to substrates. The results are interesting in the context of ...
The effect which nitrogen has upon boron diffusion through oxynitride gate dielectrics has been studied with secondary ion mass spectroscopy of polycrystalline silicon–oxynitride–silicon structures, and with x-ray photoelectron spectroscopy of silicon–boron–oxynitride–silicon structures. These studies show that the indiffusion of boron results in removal of nitrogen from the oxynitride. This in...
The elements carbon and boron uniquely form extensive series of compounds with hydrogen; hydrocarbons and boron hydrides. In comparison to carbon, which forms various chainor ring-like structures, boron, an electron deficient element, forms quasi-aromatic clusters architecturally derivable from a twelve-vertex icosahedral unit. Herein, we focus on a comparison of hydrocarbon and boron hydride b...
Plants need essential nutrients for their growth and development. Iron and boron are micronutrients that are needed by plants in very small concentrations. This study was conducted as a pot experiment to investigate the effect of iron and boron on Achillea millefolium in a factorial randomized complete design with three replications. Iron at three levels (0, 5 and 20 μM) and boron at three leve...
INTRODUCTION Complexes containing metal-boron bonds are relatively new to organometallic chemistry. Just over 20 years ago, the first crystallographically characterized complexes containing a transition metal-boron bond were reported. Boron is typically encountered in the +3 oxidation state, and boron species commonly serve as Lewis acids via their vacant p-orbital. Indeed, metal borane complex...
Boron is an essential plant micronutrient that is involved in the cell wall and membrane structure and functioinig. Boron is often found in high concentrations in association with agriculture in arid and semi-arid regions. In order to investigate the effect of zinc sulfate on some morphological, physiological and biochemical characteristics of two grapvine cultivars under toxicity of boron, a ...
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