نتایج جستجو برای: gypsum block
تعداد نتایج: 162098 فیلتر نتایج به سال:
Gypsiferous soils, as the most characteristic soil in arid and semi-arid regions, are widespread in Isfahan Province. The north-west region of Isfahan is a closed basin and is surrounded by geologic formations. This area is a part of Zayandehrood watershed. The origin of gypsum in this area was investigated in this study. Considering the geologic distribution of gypsum, twenty-two locations, su...
Applications of animal manures have increased soil test P values in many parts of the USA and thus increased the risk that soil P will be transferred to surface water and decrease water quality. To continue farming these areas, landowners need tools to reduce the risk of P losses. A field experiment was conducted near Kurten, TX, on a Zulch fine sandy loam (thermic Udertic Paleustalfs) with Bra...
The formation pathways of gypsum remain uncertain. Here, using truly in situ and fast time-resolved small-angle X-ray scattering, we quantify the four-stage solution-based nucleation and growth of gypsum (CaSO4·2H2O), an important mineral phase on Earth and Mars. The reaction starts through the fast formation of well-defined, primary species of <3 nm in length (stage I), followed in stage II by...
Abstract—In this study, the feasibility of incorporating ceramic waste from bricks (perforated brick and double hollow brick) and extruded polystyrene (XPS) waste, is analysed. Results show that it is possible to incorporate up to 25% of ceramic waste and 4% of XPS waste over the weight of gypsum in a gypsum matrix. Furthermore, with the addition of ceramic waste an 8% of surface hardness incre...
The aim of our study was to investigate how exposure to heavy metal-rich waters from gypsum mining affects the morphology and levels of primary DNA damage in Gammarus balcanicus. Chemical analysis revealed increased concentrations of metals in water and sediment collected at a site impacted by gypsum mine wastewaters. The specimens also showed elevated total tissue metal levels when compared wi...
A 3-D (3-dimensional) numerical modeling approach to analyze the coupling of mineral scale, concentration polarization and permeate flux was developed and demonstrated for a gypsum membrane scaling test in a plate-and-frame RO membrane module geometry. The impact of concentration polarization on mineral gypsum scaling, and in turn the impact of mineral scale on the concentration polarization fi...
We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we...
Reclamation of sodic soils has traditionally been undertaken using calculation of gypsum or Ca requirement assuming 100% exchange efficiency and neglect of the contribution of calcium carbonate in the profile. The UNSATCHEM model is reviewed and then evaluated for its ability to predict field reclamation of a sodic saline soil. The 40-ha field site was initially at an electrical conductivity (E...
Microbes in Haughton Crater Sulfates: Impact craters are of high interest in planetary exploration because they are viewed as possible sites for evidence of life [1]. Hydrothermal systems in craters are particularly regarded as sites where primitive life could evolve. Evidence from the Miocene Haughton impact structure shows that crater hydrothermal deposits may also be a preferred site for sub...
PURPOSE The study aimed to identify the accuracy and reproducibility of preparations made by gypsum materials of various colors using quantitative and semi-quantitative three-dimensional (3D) approach. MATERIALS AND METHODS A titanium maxillary first molar preparation was created as reference dataset (REF). Silicone impressions were duplicated from REF and randomized into 6 groups (n=8). Gyps...
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