نتایج جستجو برای: silica boron

تعداد نتایج: 55027  

2012

Boron minerals are very useful for various industrial activities, such as glass industry and detergent industry, due to its mechanical and chemical properties. During the production of boron compounds, many of these are introduced into the environment in the form of waste. Boron is also an important micro nutrient for the plants to vegetate but if it exists in high concentrations, it could have...

2017
Sylvain Jacques Alain Guette Xavier Bourrat Francis Langlais Claude Guimon Christine Labrugère

Pyrocarbon materials containing various amounts of boron have been prepared by LPCVD from BCl3–C3H8–H2 precursor mixtures. The growth rate is increased with respect to pure pyrocarbon deposition. By increasing BCl3 / (C3H8 + BCl3) ratio up to 85%, the incorporation of boron can reach 33 at.%. A small amount of boron (e.g. 8 at.%) highly enhances the anisotropy of pyrocarbon, as evidenced by opt...

Journal: :Environmental Health Perspectives 1994
H R Massie

Total boron concentrations in Drosophila changed during development and aging. The highest concentration of boron was found during the egg stage, followed by a decline during the larval stages. Newly emerged flies contained 35.5 ppm boron. During the adult stage the boron concentration increased by 52% by 9 weeks of age. Adding excess dietary boron during the adult stage decreased the median li...

Journal: :Chemical reviews 2010
Nadia Balucani Fangtong Zhang Ralf I Kaiser

The chemical reactivity of atomic boron, B(Pj), with inorganic and organic molecules is a fascinating subject of research from the experimental1-35 and theoretical viewpoints.29,30,36-46 Atomic boron resides in the same row as carbon, nitrogen, and oxygen.47 Although the reaction dynamics and kinetics of the latter elements (C, N, O) have been studied in depth,48-53 an investigation of elementa...

Journal: :Environmental Health Perspectives 1994
J G Penland

Although the trace element boron has yet to be recognized as an essential nutrient for humans, recent data from animal and human studies suggest that boron may be important for mineral metabolism and membrane function. To investigate further the functional role of boron, brain electrophysiology and cognitive performance were assessed in response to dietary manipulation of boron (approximately 0...

Journal: :Chemical science 2015
Frédéric A Perras William C Ewing Theresa Dellermann Julian Böhnke Stefan Ullrich Thomas Schäfer Holger Braunschweig David L Bryce

There is currently tremendous interest in the previously documented example of a stable species exhibiting a boron-boron triple bond (Science, 2012, 336, 1420). Notably, it has recently been stated using arguments based on force constants that this diboryne may not, in reality, feature a boron-boron triple bond. Here, we use advanced solid-state NMR and computational methodology in order to dir...

2005
Anastassia N. Alexandrova Alexander I. Boldyrev Hua-Jin Zhai Lai-Sheng Wang

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...

Journal: :journal of agricultural science and technology 0
m. brdar-jokanović institute of field and vegetable crops, maksima gorkog 30, 21000 novi sad, serbia. m. zorić institute of field and vegetable crops, maksima gorkog 30, 21000 novi sad, serbia. a. kondić-špika institute of field and vegetable crops, maksima gorkog 30, 21000 novi sad, serbia. i. maksimović faculty of agriculture, university of novi sad, trg dositeja obradovića 8, 21000 novi sad, serbia. b. kobiljski biogranum, research and development center, toplice milana 20, 21000 novi sad, serbia. m. kraljević-balalić faculty of agriculture, university of novi sad, trg dositeja obradovića 8, 21000 novi sad, serbia.

this study was aimed to assess the effects of excess boron on 59 genetically divergent wheat accessions and to identify those with high and stable yields under a range of soil boron concentrations. the second aim was to test the applicability of a laboratory technique performed at juvenile stages of development in estimating field boron tolerance. the study comprised a control and three boron t...

2004
H. A. W. El Mubarek J. M Bonar G. D. Dilliway P. Ashburn A. F. Willoughby P. L. F. Hemment

This paper investigates how the thermal diffusion of boron in silicon is influenced by a high energy fluorine implant with a dose in the range 531014–2.331015 cm−2. Secondary Ion Mass Spectroscopy (SIMS) profiles of boron marker layers are presented for different fluorine doses and compared with fluorine profiles to establish the conditions under which thermal boron diffusion is suppressed. The...

Journal: :Environmental Health Perspectives 1994
R E Newnham

Since 1963, evidence has accumulated that suggests boron is a safe and effective treatment for some forms of arthritis. The initial evidence was that boron supplementation alleviated arthritic pain and discomfort of the author. This was followed by findings from numerous other observations epidemiologic and controlled animal and human experiments. These findings included a) analytical evidence ...

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