نتایج جستجو برای: boron toxicity

تعداد نتایج: 135738  

2007
S. Mahabir M. R. Spitz S. L. Barrera Y. Q. Dong C. Eastham M. R. Forman

Hormone replacement therapy (HRT) may reduce lung cancer risk. Dietary boron may have actions similar to those of HRT; however, no previous study has reported the associations between dietary boron intake and lung cancer risk or the joint effects of boron intake and HRT use on lung cancer risk. The authors examined the associations between boron intake and the joint effects of boron intake and ...

2017
Akira Yoshinari Junpei Takano

Boron is an essential element for plants but is toxic in excess. Therefore, plants must adapt to both limiting and excess boron conditions for normal growth. Boron transport in plants is primarily based on three transport mechanisms across the plasma membrane: passive diffusion of boric acid, facilitated diffusion of boric acid via channels, and export of borate anion via transporters. Under bo...

Journal: :Plant physiology 1977
E H Birnbaum W M Dugger B C Beasley

Cotton (Gossypium hirsutum L.) ovules grown in a defined nutrient medium undergo normal morphogenesis, including fiber production. In identical medium lacking boron, ovules callus and accumulate brown substances. Boron deficiency-like symptoms were induced by 6-azauracil and 6-azauridine in ovules growing in boron-sufficient media. Other nucleoside base analogs either reduced or had no effect o...

Journal: :American journal of epidemiology 2008
S Mahabir M R Spitz S L Barrera Y Q Dong C Eastham M R Forman

Hormone replacement therapy (HRT) may reduce lung cancer risk. Dietary boron may have actions similar to those of HRT; however, no previous study has reported the associations between dietary boron intake and lung cancer risk or the joint effects of boron intake and HRT use on lung cancer risk. The authors examined the associations between boron intake and the joint effects of boron intake and ...

2016
Umit B. Demirci Philippe Miele Pascal G. Yot

The boron (Z = 5) element is unique. Boron-based (nano-)materials are equally unique. Accordingly, the present special issue is dedicated to crystalline boron-based (nano-)materials and gathers a series of nine review and research articles dealing with different boron-based compounds. Boranes, borohydrides, polyhedral boranes and carboranes, boronate anions/ligands, boron nitride (hexagonal str...

Journal: :Nature communications 2014
Yongji Gong Gang Shi Zhuhua Zhang Wu Zhou Jeil Jung Weilu Gao Lulu Ma Yang Yang Shubin Yang Ge You Robert Vajtai Qianfan Xu Allan H MacDonald Boris I Yakobson Jun Lou Zheng Liu Pulickel M Ajayan

Graphene and hexagonal boron nitride are typical conductor and insulator, respectively, while their hybrids hexagonal boron carbonitride are promising as a semiconductor. Here we demonstrate a direct chemical conversion reaction, which systematically converts the hexagonal carbon lattice of graphene to boron nitride, making it possible to produce uniform boron nitride and boron carbonitride str...

Journal: :Journal of computational chemistry 2008
Florian Janetzko Thomas Bredow Gerald Geudtner Andreas M. Köster

Boron-doped bulk diamond and the boron-doped hydrogen terminated (001) surface of diamond were investigated using the cyclic cluster model. Structure and stability of the hydrogen-terminated (001) surface were calculated and compared with experimental and other theoretical results from the literature. Boron-doping was modeled by substitution of a carbon atom by a boron atom in different positio...

Journal: :Molecules 2010
Yinghuai Zhu Xiao Siwei John A Maguire Narayan S Hosmane

This review covers the application of cycloaddition reactions in forming the boron-containing compounds such as symmetric star-shaped boron-enriched dendritic molecules, nano-structured boron materials and aromatic boronic esters. The resulting boron compounds are potentially important reagents for both materials science and medical applications such as in boron neutron capture therapy (BNCT) i...

2013
Yafang Xue Qian Liu Guanjie He Kaibing Xu Lin Jiang Xianghua Hu Junqing Hu

The insulator characteristic of hexagonal boron nitride limits its applications in microelectronics. In this paper, the fluorinated hexagonal boron nitride nanosheets were prepared by doping fluorine into the boron nitride nanosheets exfoliated from the bulk boron nitride in isopropanol via a facile chemical solution method with fluoboric acid; interestingly, these boron nitride nanosheets demo...

2005
Rolf L. Romer Anette Meixner

The isotopic analysis of boron from material that carries only trace amounts of boron requires low boron blank levels. Large efforts are taken to keep blank levels low by purifying reagents. We performed exposure experiments and determined procedure blanks before and after the air-handling system was modified from silicate glass filters to polyethylene/polystyrole and active carbon filters. Our...

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