نتایج جستجو برای: elemental carbon
تعداد نتایج: 299121 فیلتر نتایج به سال:
Our understanding of elemental cycling in the ocean, its mechanisms and implications for ecology and climate, has undergone revolutionary change since the previous SCOPE volume was published in 1983 (Bolin and Cook 1983). The most notable of the advances in ocean biogeochemistry concern the role of the oceans in the global carbon cycle (Hanson, Ducklow, and Field 2000) and recognition of iron a...
This paper investigates the reactivity of elemental carbon films deposited from the vapor phase with Fe and Ni substrates at room temperature. X-ray photoelectron spectroscopy (XPS) measurements are presented as a method for evaluating kinetic reaction data. Carbon films are deposited on different surface orientations representing geometries from a dense atom packing as in fcc (111) to an open ...
A novel sulfur nanocomposite was fabricated based on graphitic mesoporous carbon.The graphitic mesoporous carbon was synthesized using sucrose as carbon precursor, nano CaCO3 as a hard template and nickel nitrate as graphitization catalyst. The structural properties of the prepared material were characterized using powder X-Ray Diffraction (XRD), N2-adsorption/de...
We have measured spectral albedo, as well as ancillary parameters, of seasonal European Arctic snow at Sodankylä, Finland (6722 N, 2639 E). The springtime intensive melt period was observed during the Snow Reflectance Transition Experiment (SNORTEX) in April 2009. The upwelling and downwelling spectral irradiance, measured at 290–550 nm with a double monochromator spectroradiometer, revealed al...
Elucidation of the chemical logic of life is one of the grand challenges in biology, and essential to the progress of the upcoming field of synthetic biology. Treatment of microbial cells explicitly as a "chemical" species in controlled reaction (growth) environments has allowed fascinating discoveries of elemental formulae of a few species that have guided the modern views on compositions of a...
Aerosols have both direct and indirect effects on climate. The direct effect is characterized by a particle’s ability to scatter and absorb radiation. These particles can also nucleate cloud droplets. Once activated, these cloud condensation nuclei (CCN) can go on to form clouds, which also scatter and absorb radiation (the indirect aerosol effect). Changing aerosol size and chemistry will affe...
In autumn 2017, an experiment was conducted for the reduction of carbon monoxide (CO) emissions commissioned by Holmen Paper Braviken, one of the world’s most production-efficient paper mills. Digitalization has increased in recent years, which has resulted in a decreased demand for graphic paper. The goal of finding cost-reducing solutions in the manufacturing process has been increased in Hol...
Fine roots constitute a significant source of plant productivity and litter turnover across terrestrial ecosystems, but less is known about the quantitative and qualitative profile of phenolic compounds within the fine-root architecture, which could regulate the potential contribution of plant roots to the soil organic matter pool. To understand the linkage between traditional macro-elemental a...
A small spirillum, designated 5175, was isolated from an anaerobic enrichment culture for Desulfuromonas in which the major medium constituents were acetate and elemental sulfur. The organisms grew only under anaerobic or microaerophilic conditions. Elemental sulfur was formed anaerobically in a malate-sulfide medium, and cell densities of 10(8) cells/ml were obtained. Hydrogen and formate were...
Health risk assessments of particulate matter less than 2.5 μm in diameter (PM(2.5)) often assume that all constituents of PM(2.5) are equally toxic. While investigators in previous epidemiologic studies have evaluated health risks from various PM(2.5) constituents, few have conducted the analyses needed to directly inform risk assessments. In this study, the authors performed a literature revi...
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