نتایج جستجو برای: element boron

تعداد نتایج: 221337  

Journal: :journal of nanostructures 2012
a. ghorbanpour arani s. shams s. amir z. khoddami maraghi

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...

Journal: :Cancer research 1994
S L Kraft P R Gavin C W Leathers C E DeHaan W F Bauer D L Miller R V Dorn M L Griebenow

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 ...

1998
Ramón J. Garćıa López David L. Lambert Bengt Edvardsson Bengt Gustafsson Dan Kiselman Rafael Rebolo

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...

Journal: :Digestive and liver disease : official journal of the Italian Society of Gastroenterology and the Italian Association for the Study of the Liver 2015
Leslie Rinaldi Gabriele Barabino Jean-Philippe Klein Dimitrios Bitounis Jérémie Pourchez Valérie Forest Delphine Boudard Lara Leclerc Gwendoline Sarry Xavier Roblin Michèle Cottier Jean-Marc Phelip

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...

2010

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...

Journal: :Physical chemistry chemical physics : PCCP 2014
Wen-Juan Tian Hong-Guang Xu Xiang-Yu Kong Qiang Chen Wei-Jun Zheng Hua-Jin Zhai Si-Dian Li

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 ...

Journal: :The New phytologist 2017
Benjamin L Turner Paul-Camilo Zalamea Richard Condit Klaus Winter S Joseph Wright James W Dalling

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 ...

Journal: :physiology and pharmacology 0
mohammad reza naghii tehran- iran mahmood mofid ali reza asgari mahdi hedayati maryam sadat daneshpour

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...

Journal: :Annual review of plant physiology and plant molecular biology 1998
Dale G. Blevins Krystyna M. Lukaszewski

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...

Journal: :Journal of the American Chemical Society 2007
Michiel J van Setten Matthé A Uijttewaal Gilles A de Wijs Robert A de Groot

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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