نتایج جستجو برای: pumice stone
تعداد نتایج: 26206 فیلتر نتایج به سال:
Calcium aluminate cements (CACs) are a group of rapid-hardening hydraulic binders with higher aluminum composition and lower ecological footprint compared to their ordinary Portland cement (CEM) counterparts. CACs commonly known have thermo-durability properties but previously been observed experience major strength loss over time when exposed thermal humidity conditions due the chemical conver...
The geometry of mesoscopic single and multiple layer folds in rhyolitic obsidian ̄ows is investigated. Folds are composed of obsidian embedded in a matrix of pumice. Folds form by buckling processes as indicated by discontinuous deformation between obsidian and pumice layers and by the geometries of wavetrains. Buckling occurs through a continuum of styles controlled largely by the thickness ra...
Wastewater treatment of some heavy metals was carried out by synthetic zeolite P1, which was prepared by alkaline hydrothermal treatment of the pumice. Both of the pumice raw materials and synthetic zeolite were investigated for their chemical phase composition, physical properties, and microstructure. The adsorption behavior of Na-zeolite P1 with respect to Co(+2), Cu(+2), Fe(+2), and Cd(+2) h...
Microcystins (MCs) are among the most prevalent and potent of the cyanobacterial toxins (cyanotoxins) and their potential occurrence in waters required for drinking has prompted investigations into remedial water treatments for their removal. We have investigated the suitability of local pumice, as a possible low-cost material for environmental application for the removal of cyanotoxins. Adsorp...
The 2012 submarine eruption of Havre volcano in the Kermadec arc, New Zealand, is the largest deep-ocean eruption in history and one of very few recorded submarine eruptions involving rhyolite magma. It was recognized from a gigantic 400-km2 pumice raft seen in satellite imagery, but the complexity of this event was concealed beneath the sea surface. Mapping, observations, and sampling by subme...
Pumice and the Moringa oleifera (MO) seed were investigated as alternative natural materials for drinking water treatment based on problems identified at the Stretta Vaudetto water treatment plant in Eritrea. Lab and pilot scale studies showed that pumice was a suitable alternative material for dual media filtration. Conversion of the sand filters at Stretta Vaudetto to pumice-sand media would ...
BACKGROUND The objective was to perform a comparative analysis of the effect of acid etching on enamel roughness between pumiced and non-pumiced teeth. MATERIALS AND METHODS The sample was composed of 32 dental surfaces divided into two groups: Group 1-16 surfaces having received pumice prophylaxis; and Group 2-16 surfaces not having received pumice prophylaxis. The teeth were kept in saline ...
abstract: the present study is an attempt to find out cultural exophoric references in iranian high-school elt textbooks and touch stone series to compare the frequency of occurrence of such references in these books. the purpose is to find out which of the series of the books under investigation impose a greater referential burden on efl learners as far as their reading comprehension of the ...
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