نتایج جستجو برای: boron impurity
تعداد نتایج: 27799 فیلتر نتایج به سال:
As attractive analogue of graphene, boron monolayers have been theoretically predicted. However, due to electron deficiency of boron atom, synthesizing boron monolayer is very challenging in experiments. Using first-principles calculations, we explore stability and growth mechanism of various boron sheets on Cu(111) substrate. The monotonic decrease of formation energy of boron cluster B(N) wit...
In this letter we extend previously established results for nested carbon nanocones to both nested boron nitride and carbon-boron nitride nanocones. Based purely on mechanical principles and classical mathematical modelling techniques, we determine the energetically favourable structures for nested boron nitride and carbon-boron nitride nanocones. While only three apex angles for boron nitride ...
changes of major wall polysaccharides and glycoproteins of tobacco cells in response to excess boron
effects of excess concentrations of boron on major cell wall components of tobacco cells(nicotiana tabacum l. cv. burley 21) were studied. pectin, xyloglucan, hydroxyproline-richglycoproteins (extensin), and arabinogalactan proteins were characterized. results showedthat increased boron supply resulted in significant decrease in cell and cell wall dry weights.also, high concentrations of boron ...
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...
The application of boron neutron capture therapy to rheumatoid arthritis requires the selective delivery of the boron-10 isotope to the synovitic tissue. The use of liposomes as a boron delivery method has been explored through the measurement of the time course biodistribution of boron in rats with collagen-induced arthritis (CIA). Small unilamellar vesicles were composed of a 1:1 mixture of d...
Boron is an essential mineral nutrient for higher plant growth and development. However, excessive amounts of boron can be toxic. Here, we report on the characterization of an Arabidopsis mutant, shb1 (sensitive to high-level of boron 1), which exhibits hypersensitivity to excessive boron in roots. Positional cloning demonstrated that the shb1 mutant bears a point mutation in a gene encoding a ...
The functional properties of the Saccharomyces cerevisiae bicarbonate transporter homolog Bor1p (YNL275wp) were characterized by measuring boron (H(3)BO(3)), Na(+), and Cl(-) fluxes. Neither Na(+) nor Cl(-) appears to be a transported substrate for Bor1p. Uphill efflux of boron mediated by Bor1p was demonstrated directly by loading cells with boron and resuspending in a low-boron medium. Cells ...
We present exact analytical calculations of scanning tunneling currents in locally disordered graphene using a multimode description of the microscope tip. Analytical expressions for the local density of states (LDOS) are given for energies beyond the Dirac cone approximation. We show that the LDOS at the A and B sublattices of graphene are out of phase by π implying that the averaged LDOS, as ...
For over twenty years boron has been of interest to investigators confirming the safety and essentiality of the element in humans. Fruits, vegetables, nuts, and pulses are natural sources of boron in the diet which world wide averages about 1-3 mg daily for most adults. In boron-rich regions of Turkey drinking water sources with 29 mg boron/liter are consumed without harmful effects. The Europe...
Recent work on atomic-precision dopant incorporation technologies has led to the creation of both boron and aluminum δ-doped layers in silicon with densities above solid solubility limit. We use density functional theory predict band structure effective mass values such δ layers, first modeling them as ordered supercells. Structural relaxation is found have a significant impact impurity energie...
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