scholarly journals Nanoparticles and nanofluids in “water–rock” interactions

2019 ◽  
Vol 64 (4) ◽  
pp. 343-355
Author(s):  
V. A. Alekseyev
Keyword(s):  
Natural Waters ◽  
Energy Conditions ◽  
Geochemical Processes ◽  
Gas Migration ◽  
Pressure Surface ◽  
Inner Pressure ◽  
Change Behavior ◽  
Main Development ◽  
Formation And Evolution ◽  
Small Content

A brief review of published papers was done in nanogeochemistry, a new field of geochemistry in which particles and fluids of small size (<100 nm) were investigated. They are different in properties from their larger analogs because of the greater contributions of their surface energy. Conditions, forms, and mechanisms of their formation and evolution were considered. Examples of size dependencies of nanoparticle and nanofluid properties (solubility and stability, melting temperature, inner pressure, surface charge and sorption, rates of evaporation, chemical reactions, and transport) were shown. Different influence of convex and concave surface on properties was noted. Widespread distribution of nanoparticles and nanofluids in nature provides their influence on various geochemical processes. Nanoparticles sorbs heavy metals and are the main form of their transport in natural waters. Nanofluids (nanopors) control the processes of diagenesis, metasomatic substitution and weathering, gas migration in shales. Even with a small content, nanoparticles can change behavior of macro systems dramatically. The main development directions of nanogeochemistry were summarized.

scholarly journals Exact Relativistic Magnetized Haloes around Rotating Disks

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Antonio C. Gutiérrez-Piñeres ◽  
Abraão J. S. Capistrano
Keyword(s):  
Charged Particle ◽  
Energy Momentum Tensor ◽  
Rotating Disk ◽  
Momentum Tensor ◽  
Energy Conditions ◽  
Rotating Disks ◽  
Relativistic Model ◽  
Asymptotically Flat ◽  
Relativistic Treatment ◽  
Formation And Evolution

The study of the dynamics of magnetic fields in galaxies is one of important problems in formation and evolution of galaxies. In this paper, we present the exact relativistic treatment of a rotating disk surrounded by a magnetized material halo. The features of the halo and disk are described by the distributional energy-momentum tensor of a general fluid in canonical form. All the relevant quantities and the metric and electromagnetic potentials are exactly determined by an arbitrary harmonic function only. For instance, the generalized Kuzmin-disk potential is used. The particular class of solutions obtained is asymptotically flat and satisfies all the energy conditions. Moreover, the motion of a charged particle on the halo is described. As far as we know, this is the first relativistic model describing analytically the magnetized halo of a rotating disk.

scholarly journals Tungsten Accumulation in Hot Spring Sediments Resulting from Preferred Sorption of Aqueous Polytungstates to Goethite

2021 ◽  
Vol 18 (23) ◽  
pp. 12629
Author(s):  
Qian Zhao ◽  
Qinghai Guo ◽  
Li Luo ◽  
Ketao Yan
Keyword(s):  
Laboratory Experiments ◽  
Natural Waters ◽  
Hot Springs ◽  
Hot Spring ◽  
Geochemical Processes ◽  
Geothermal Systems ◽  
Geothermal Waters ◽  
Acidic Conditions ◽  
Outflow Channel ◽  
Iron Bearing

Geothermal waters usually have elevated tungsten concentrations, making geothermal systems important sources of tungsten in the environment. To study the transport of tungsten in hot springs to hot spring sediment, which is one of the key processes for the release of geothermally derived tungsten to the surface environment, geochemical investigations of the hot springs and their corresponding sediments in Rehai (a representative hydrothermal area in southwestern China) and systematic laboratory experiments of tungstate and polytungstate adsorption onto typical iron-bearing minerals in hot spring sediments (i.e., pyrite and goethite) were conducted. The results demonstrate that considerable tungsten concentrations (i.e., not much less than 10 µg/L), formation of polytungstates under acidic conditions, and enrichment of iron oxide minerals represented by goethite are the prerequisites for extreme enrichment of tungsten in hot spring sediments (e.g., 991 µg/g in the ZZQ spring outflow channel). The absence of any of these conditions would weaken the immobilization of aqueous tungsten and result in higher mobility of tungsten in the hot springs and its further transport downstream, possibly polluting the other natural waters in and around Rehai that serve as local drinking water sources. This study provides an insight for identifying the key geochemical processes controlling the transport and fate of undesirable elements (in this case, tungsten) in geothermal systems.

scholarly journals The use of geochemical ratios in groundwater quality assessment: the case of the Thriassion Plain, Attica, Greece

2019 ◽  
Vol 55 (1) ◽  
pp. 223
Author(s):  
Panayota Makri ◽  
Dimitrios Hermides ◽  
Maria Psychogiou ◽  
Aikaterini Ermidou
Keyword(s):  
Groundwater Quality ◽  
Natural Waters ◽  
Groundwater Salinity ◽  
Geochemical Processes ◽  
Fresh Groundwater ◽  
Water Interaction ◽  
Clay Deposits ◽  
Rock Water Interaction ◽  
Groundwater Samples ◽  
Chadha’S Diagram

This paper is an effort to assess the groundwater quality and the geochemical processes mainly using the Chadha’s diagram which classifies natural waters and documents the Piper and extended Durov diagrams. Chadha’s diagram is a useful tool to interpret groundwater geochemical processes because it is produced by simple spreadsheets excel files. The example of hydrochemical analyses were given from groundwater samples of the Thriassion Plain. To attend our objective, 38 groundwater samples were collected. Hydrochemical sections, XY diagrams, distribution maps of ionic ratios as well as the Gibbs diagrams were used to identify origin of salinity and the hydrogeochemical processes that have taken place. The Gibbs diagrams have shown that evapotranspiration (ET) and rock-water interaction play an important role to the increase of groundwater salinity. The interpretation of Chadha diagram highlights that the stratigraphic factors and especially the clay strata occurrence have isolated fresh groundwater from seawater. The abundant occurrence of clay deposits to the depth of the plain work as barriers to direct seawater intrusion. Good quality groundwater identified confirms the important role of clay strata. Reverse cation exchange, is the predominant geochemical process in the Thriassion Plain aquifers, whereas evapotranspiration (ET) and rock-water interaction play an important role to the increase of groundwater salinity.

Techniques for preparing the Lolium perenne coleorhiza for scanning electron microscope evaluation

1992 ◽  
Vol 50 (1) ◽  
pp. 766-767
Author(s):  
Susan B.G. Debaene ◽  
John S. Gardner ◽  
Phil S. Allen
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Lolium Perenne ◽  
Morphological Study ◽  
Root Hairs ◽  
Inner Pressure ◽  
Water Potentials ◽  
Radicle Emergence ◽  
Standard Fixation ◽  
Scanning Electron

The coleorhiza is a nonvascular sheath that encloses the embryonic radicle in Poaceae, and is generally the first tissue to emerge during germination. Delicate hairlike extensions develop from some coleorhiza cells prior to radicle emergence. Similar to root hairs, coleorhiza hairs are extremely sensitive to desiccation and are damaged by exposure to negative water potentials. The coleorhiza of Lolium perenne is somewhat spherical when first visible, after which a knob forms at a right angle to the caryopsis due to inner pressure from the elongating radicle. This knob increases in length until the radicle finally punctures the coleorhiza. Standard fixation procedures cause severe desiccation of coleorhiza cells and hairs, making morphological study of the coleorhiza difficult. This study was conducted to determine a more successful process for coleorhiza preservation.

AFM study of the dynamics of α-alumina surface faceting during high-temperature processing

1995 ◽  
Vol 53 ◽  
pp. 334-335 ◽  
Author(s):  
Michael W. Bench ◽  
Jason R. Heffelfinger ◽  
C. Barry Carter
Keyword(s):  
High Temperature ◽  
Thin Foil ◽  
Sem Analysis ◽  
Conductive Coatings ◽  
Force Microscopy ◽  
Minimal Sample ◽  
Atomic Force ◽  
Formation And Evolution ◽  
High Temperature Processing ◽  
Nominal Surface

To gain a better understanding of the surface faceting that occurs in α-alumina during high temperature processing, atomic force microscopy (AFM) studies have been performed to follow the formation and evolution of the facets. AFM was chosen because it allows for analysis of topographical details down to the atomic level with minimal sample preparation. This is in contrast to SEM analysis, which typically requires the application of conductive coatings that can alter the surface between subsequent heat treatments. Similar experiments have been performed in the TEM; however, due to thin foil and hole edge effects the results may not be representative of the behavior of bulk surfaces.The AFM studies were performed on a Digital Instruments Nanoscope III using microfabricated Si3N4 cantilevers. All images were recorded in air with a nominal applied force of 10-15 nN. The alumina samples were prepared from pre-polished single crystals with (0001), , and nominal surface orientations.

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