نتایج جستجو برای: element boron
تعداد نتایج: 221337 فیلتر نتایج به سال:
using principle of minimum total potential energy approach in conjunction with rayleigh-ritz method, the electro-thermo-mechanical axial buckling behavior of piezoelectric polymeric cylindrical shell reinforced with double-walled boron-nitride nanotube (dwbnnt) is investigated. coupling between electrical and mechanical fields are considered according to a re...
Borocaptate sodium (Na2B12H11SH) is a potentially useful compound for boron neutron capture therapy of intracranial tumors. Tumor and normal tissue boron concentrations were evaluated in 30 dogs with naturally occurring intracranial tumors after i.v. borocaptate sodium infusion (55 mg boron/kg). Postmortem tissue boron concentrations were measured for three postinfusion time periods (2, 6, and ...
We have observed the B I λ 2497 Å line to derive the boron abundances of two very metal-poor stars selected to help in tracing the origin and evolution of this element in the early Galaxy: BD +23◦3130 and HD 84937. The observations were conducted using the Goddard High Resolution Spectrograph on board the Hubble Space Telescope. A very detailed abundance analysis via spectral synthesis has been...
BACKGROUND Some studies have linked colorectal cancer to metal exposure. AIMS Our objective was to evaluate the element distribution in colorectal adenocarcinoma biopsies, adjacent non-tumour tissues, and healthy controls. METHODS The study is a case-control study which compared the element distribution in colon biopsies from two groups of patients: with colorectal cancer (2 types of sample...
Boron is a widely occurring element in minerals found in the earth’s crust. It is the 51 most common element found in the earth’s crust and is found at an average concentration of 8 mg/kg (approximately 0.0008%). It is found in the environment primarily combined with oxygen in compounds called borates. Common borate compounds include boric acid, salts of boric acid (e.g., sodium tetraborates, w...
We report on the structural and electronic properties and chemical bonding in a series of lithium and gold alloyed boron oxide clusters: B2O3(-), LiB2O3(-), AuB2O3(-), and LiAuB2O3(-). The clusters have been produced by laser vaporization and characterized using photoelectron spectroscopy, in combination with the Coalescence Kick and Basin Hopping global-minimum searches and density-functional ...
It was recently proposed that boron might be the most important nutrient structuring tree species distributions in tropical forests. Here we combine observational and experimental studies to test this hypothesis for lowland tropical forests of Panama. Plant-available boron is uniformly low in tropical forest soils of Panama and is not significantly associated with any of the > 500 species in a ...
introduction: boron possesses widespread properties and is important for human and animal nutrition. since boron is rapidly bioavailable, the objective of the present study was to determine whether acute (hourly or daily), and weekly supplementationcould have any significant biological effects on the synthesis of steroids as well as inflammatory biomarkers. methods: eight male volunteers partic...
New and exciting developments in boron research in the past few years greatly contributed to better understanding of the role of boron in plants. Purification and identification of the first boron-polyol transport molecules resolved much of the controversy about boron phloem mobility. Isolation and characterization of the boron-polysaccharide complex from cell walls provided the first direct ev...
Its low weight, high melting point, and large degree of hardness make elemental boron a technologically interesting material. The large number of allotropes, mostly containing over a hundred atoms in the unit cell, and their difficult characterization challenge both experimentalists and theoreticians. Even the ground state of this element is still under discussion. For over 30 years, scientists...
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