نتایج جستجو برای: elemental carbon

تعداد نتایج: 299121  

Journal: :Journal of synchrotron radiation 1998
A Ito K Shinohara Y Mizukami H Nakano K Yada T Uehara T Honda

An X-ray contact microscopy system has been developed for the study of molecular and elemental distributions in biological specimens based on X-ray absorption characteristics. The system consists of a chamber for measuring XANES (X-ray absorption near-edge structure) of biomolecules, and a contact microscopy system for dried specimens with an electronic zooming tube. With this system the elemen...

Journal: :Journal of the Air & Waste Management Association 2010

2009
Aruna Velamakanni K. J. Ganesh Yanwu Zhu Paulo J. Ferreira Rodney S. Ruoff

Catalyst-free growth of boron carbide nanowires is achieved by pyrolysis of diborane and methane at 650–750 -C and around 500 mTorr in a quartz tube furnace. Electron-diffraction analysis using a novel diffraction-scanning transmission electron microscopy (D-STEM) technique indicates that the crystalline nanowires are single-crystal orthorhombic boron carbide. TEM images show that the nanowires...

Journal: :Molecules 2012
Parviz Torabi Javad Azizian Shahab Zomorodbakhsh

We found that elemental iodine and bromine are converted to trihalide nucleophiles (triiodine and tribromide anion, respectively) in the presence of catalytic amounts of meso-tetraphenylporphyrins (H2TPP). Therefore a highly regioselective method for the synthesis of beta-haloalcohols through direct ring opening of epoxides with elemental iodine and bromine in the presence of H2TPPs as new cata...

Karim Zare Mahmood Ghoranneviss Sepideh Sadat Madani

A systematic study was conducted to understand the influences of catalyst combination as Ni-Co NPs on carbon nanotubes (CNTs) grown by Chemical Vapor Deposition (TCVD). The DC-sputtering system was used to prepare Co and Ni-Co thin films on silicon substrate. Ni- Co nanoparticles were used as metal catalyst for growing carbon nanotubes from acetylene (C2H2) gas in 850 ̊ C during 15 min. Carb...

Journal: :Ecology letters 2006
Paul C Frost Jonathan P Benstead Wyatt F Cross Helmut Hillebrand James H Larson Marguerite A Xenopoulos Takehito Yoshida

Inadequate supply of one or more mineral elements can slow the growth of animal consumers and alter their physiology, life history and behaviour. A key concept for understanding nutrient deficiency in animals is the threshold elemental ratio (TER), at which growth limitation switches from one element to another. We used a stoichiometric model that coupled animal bioenergetics and body elemental...

Journal: :Science 1979
J J Griffin E D Goldberg

Carbon particles extracted from sediments collected by box coring from southeastern Lake Michigan were compared with carbon particles extracted from oil, coal, and wood fly ash. Sediments deposited after 1900 contained coal, oil, and wood carbons; older sediments contained only wood carbon.

2009
D. Dissard G. Nehrke G. J. Reichart

Evidence of increasing concentrations of dissolved carbon dioxide, especially in the surface ocean and its associated impacts on calcifying organisms, is accumulating. Among these organisms, benthic and planktonic foraminifera are responsible for a large amount of the globally precipitated calcium carbonate. Hence, their response to an acidifying ocean may have important consequences for future...

2013
Fuwang Zhang Jinsheng Chen Tianxue Qiu Liqian Yin Xiaoqiu Chen Jianshuan Yu

In this study, mass concentrations and chemical compositions of fine particles, mass concentrations of coarse particles, light extinction, and meteorological parameters in the atmosphere of Xiamen were presented and analyzed to study the chemical and optical characteristics of a typical haze episode from Dec 25, 2010 to Jan 1, 2011. The major chemical compositions of PM2.5, such as water solubl...

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