Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Sulfur has many redox states and is a major metabolite in suboxic and anaerobic environments including, but not restricted to, marine and marginal marine sediments, the water column of oxygen minimum zones, salt marshes and oil wells. Microbially mediated redox cycling of sulfur typically comprises dissimilatory sulfate reduction (MSR), sulfide reoxidation, disproportionation and the oxidation and reduction of sulfur redox intermediates. These processes contribute to the degradation of organic matter, link the cycles of sulfur and carbon, control the production and consumption of methane and are critical for the long term budget of O2 in the atmosphere. Microbial and abiotic processes at redox interfaces also connect the sulfur cycle to the redox cycles of nitrogen, iron and other elements, producing distinctive geochemical and molecular signatures. Studies that couple microbiology with stable isotope geochemistry have informed interpretations of microbial sulfur cycling in modern and past environments. Laboratory-based studies and models of MSR have sought to understand the physiological and environmental controls of the magnitude of sulfur isotope fractionation. The fractionations of stable sulfur and oxygen isotopes during MSR are also used to track enzymatic activity during MSR and processes that oxidize sulfide in the presence of environmental oxidants. Outstanding questions in the field concern the importance of oxidative processes within the natural environment, the delivery of oxidants and carbon sources to the zones of sulfate reduction and the ability to detect or reconstruct oxidative processes from the chemical, isotopic, metagenomic, transcriptomic, proteomic and metabolomics profiles in the environment. Recent studies have emphasized the complex connections between sulfur and methane, iron, nitrogen and other elements. These links may involve the redox cycling of species that occur at concentrations difficult to detect by standard geochemical techniques or that are cycled at very rapid rates (cryptic cycles). Of particular interest is the use of isotope geochemistry to quantify links among various electron acceptors, including sulfate, ferric iron, and nitrate, during the anaerobic methane oxidation. For example, recent geochemical measurements have hinted that microbial sulfate reduction coupled to organic matter oxidation is mechanistically different to when sulfate reduction is coupled to methane oxidation. Recent studies have also suggested a possible contribution of a number of previously uncultured microbial groups in sulfur cycling in sulfidic environments, inspiring further studies of these organisms and their partnerships in anaerobic environments. This Research Topic highlights studies of microbial interactions, processes and communities that couple the sulfur cycle to the cycles of other elements in aphotic environments.

issimilatory sulfate reduction (MSR) --- subsurface sulfur cycle --- sulfur

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Sulfur dioxide. --- Sulfur compounds. --- Sulphur compounds --- Chemicals --- Sulfurous anhydride --- Sulphur dioxide --- Sulfur oxides

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

An attractive simplification of PEM-FC systems operated with natural gas would be the use of a sulfur tolerant reforming catalyst, but such a catalyst has not been available thus far. In this work it is demonstrated that a tailor made rhodium catalyst retains useful activity for typical sulfur levels in the feed. A brief economic comparison showed however that this alternative process is still less economical than the traditional process employing removal of sulfur components by adsorption.

natural gas --- reforming --- fuel cells --- sulfur --- hydrogen

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

This volume on iron-sulfur proteins includes chapters that describe the initial discovery of iron-sulfur proteins in the 1960's to elucidation of the roles of iron sulfur clusters as prosthetic groups of enzymes, such as the citric acid cycle enzyme, aconitase, and numerous other proteins, ranging from nitrogenase to DNA repair proteins. The capacity of iron sulfur clusters to accept and delocalize single electrons is explained by basic chemical principles, which illustrate why iron sulfur proteins are uniquely suitable for electron transport and other activities. Techniques used for detection and stabilization of iron-sulfur clusters, including EPR and Mossbauer spectroscopies, are discussed because they are important for characterizing unrecognized and elusive iron sulfur proteins. Recent insights into how nitrogenase works have arisen from multiple advances, described here, including studies of high-resolution crystal structures. Numerous chapters discuss how microbes, plants, and animals synthesize these complex prosthetic groups, and why it is important to understand the chemistry and biogenesis of iron sulfur proteins. In addition to their vital importance in mitochondrial respiration, numerous iron sulfur proteins are important in maintenance of DNA integrity. Multiple rare human diseases with different clinical presentations are caused by mutations of genes in the iron sulfur cluster biogenesis pathway. Understanding iron sulfur proteins is important for understanding a rapidly expanding group of metabolic pathways important in all kingdoms of life, and for understanding processes ranging from nitrogen fixation to human disease.

Iron-sulfur proteins. --- Iron sulphur proteins --- Sulfur-iron proteins --- Iron proteins --- Organosulfur compounds

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Utilization of high sulfur coals is becoming increasingly difficult in view of tighter environmental regulations being imposed around the world. To meet the challenge of utilizing high sulfur coals without damaging the environment, many scientists and engineers around the world are engaged in developing novel technologies. In the U.S.A. alone, the federal government has spent about five billion dollars to achieve that goal. This conference, like its predecessors, emphasizes desulfurization with papers on physical and chemical cleaning as well as post-treatment and fluid-bed combustion technolo

Coal --- Caustobioliths --- Fossil fuels --- Sulfur content --- Desulfurization --- Environmental aspects