نتایج جستجو برای: boron impurity

تعداد نتایج: 27799  

Journal: :The Journal of chemical physics 2013
Haigang Lu Si-Dian Li

Using the first principle methods, we proposed a series of three-chain boron cages B6n+14 (n = 1-12) which are mainly built by fusing three boron semi-double-rings. Their simple geometric structures (approximate D3 or C3 symmetry) facilitate their bottom-up syntheses from the hexagonal B7 and the double-chain boron clusters, such as B2, B4, B6, B8H2, B10H2, B12H2, and the double ring B20. The s...

Journal: :Plant physiology 1965
L S Albert

Boron is recognize(d as an essential micronutrient for higher plants, but the precise role of this element in plant growth and development is not clear. In Gaugh and Dugger's (3) comprehensive review they presented and discussed a wide spectrum of proposed roles and effects of boron on higher plants. From their own work and their interpretative review of the literature they concluded that "boro...

2003
J CUEVAS

We analyze the influence of an impurity in the evolution of moving discrete breathers in a Klein–Gordon chain with non-weak nonlinearity. Three different behaviours can be observed when moving breathers interact with the impurity: they pass through the impurity continuing their direction of movement; they are reflected by the impurity; they are trapped by the impurity, giving rise to chaotic br...

2012
Balasubramanian Satheesh Kondayampettai K. Sree Ganesh Dhandayutham Saravanan

An unknown impurity formed during stability sample analysis by a gradient reversed phase ultra-high pressure liquid chromatography (UHPLC) of varenicline tablets at 0.2% level. A simple isocratic preparative method was developed to isolate the unknown impurity with 20 min run time. This unknown impurity was identified and characterized by using spectroscopic techniques. Based on the spectral da...

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...

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