نتایج جستجو برای: hydrothermal conditions
تعداد نتایج: 862579 فیلتر نتایج به سال:
Introduction: Impact events locally increase the temperature of a planetary crust, initiating hydrother-mal activity if water or ice is present. Impact-induced hydrothermal activity is responsible for mineralogical-ly and morphologically modifying many terrestrial craters [e.g., 1], and has been suggested for Martian craters [2, 3]. Present-day subsurface ice has been inferred at high latitudes...
Biodiesel has become an attractive fuel recently, because it is renewable, non-toxic, biodegradable, environmentally friendly, etc. With the increase in the production of biodiesel, the problem of disposing crude glycerol, which is produced as main by-product from biodiesel process such as transesterification, has been raised. Therefore, we have been developing a new green technology-Hydrotherm...
Two mesostructured MCM-41 silicas that differ dramatically in hydrothermal stability have been examined by (29)Si MAS NMR spectroscopy and pair distribution function (PDF) analysis of synchrotron X-ray scattering data. The less stable mesostructure assembled from sodium silicate and the substantially more stable derivative made from fumed silica possess equivalent local framework wall structure...
Subseafloor mixing of reduced hydrothermal fluids with seawater is believed to provide the energy and substrates needed to support deep chemolithoautotrophic life in the hydrated oceanic mantle (i.e., serpentinite). However, geosphere-biosphere interactions in serpentinite-hosted subseafloor mixing zones remain poorly constrained. Here we examine fossil microbial communities and fluid mixing pr...
The mechanism of C-H activation in selective oxidation reactions of short-chain alkane molecules over transition metal oxides is critically affected by the balance of acid-base and redox sites at the surface of the catalyst. Using the example of manganese tungstate we discuss how the relative abundance of these sites can be controlled via synthetic techniques. Phase-pure catalysts composed of t...
up to now, lots of materials such as active carbon, iron, manganese, zirconium, and metal oxides have been widely used for removal of dyes from contaminated water. among these, ferrite nanoparticle is an interesting magnetic material due to its moderate saturation magnetization, excellent chemical stability and mechanical hardness. graphene, a new class of 2d carbonaceous material with atom thi...
Thermodynamic modelling of organic synthesis has largely been focused on deep-sea hydrothermal systems. When seawater mixes with hydrothermal fluids, redox gradients are established that serve as potential energy sources for the formation of organic compounds and biomolecules from inorganic starting materials. This energetic drive, which varies substantially depending on the type of host rock, ...
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