نتایج جستجو برای: polymorph crystalline silica
تعداد نتایج: 77663 فیلتر نتایج به سال:
The metastable ilmenite polymorph of NaNbO(3), instead of the expected perovskite polymorph, may be prepared directly in one step under mild hydrothermal conditions by lowering pH and using close to stoichiometric amounts of metal precursors; in situ energy-dispersive X-ray diffraction shows that crystallisation occurs rapidly via a sequence of intermediate crystalline phases.
Calcium carbonate is the most abundant biomineral and a compound of great industrial importance. Its precipitation from solution has been studied extensively and was often shown to proceed via distinct intermediate phases, which undergo sequential transformations before eventually yielding the stable crystalline polymorph, calcite. In the present work, we have investigated the crystallisation o...
Enzymatic hydrolysis of non-dried and dried cellulose samples having various particles size, degree of polymerization, porosity, crystalline polymorph, and content of non-crystalline domains has been studied. Regression analysis was carried out to determine contribution of various structural features of cellulose samples to their hydrolysability. It was found that particle size, degree of polym...
Background and aims: The term "crystalline silica", refers to crystallized form of SiO2 and quartz, as the most abundant compound in earth crust.I It can cause silicosis and lung cancer following inhalation of large doses in course of occupational exposure. Silica exposure is unavoidable during demolition of buildings and therefore it can lead to many problems for demolition workers’ health. ...
Objectives: This study aimed to assess exposure to crystalline silica and its relation with risk of pulmonary functional disorders among workers of a cement industry in Saveh, Iran.Methods: In this cross-sectional study, 62 samples of respirable dust were collected from breathing zone of workers in different sections of a 4-years-old cement factory in 2011. Determination ofrespirable dust conce...
X-ray in situ studies in electrically and laser-heated diamond anvil cells (DACs) at pressures over 80 GPa and temperatures above 2500 K were used to determine stable silica phase at extreme conditions. We demonstrate that so far unidenti®ed phases obtained on the compression of a-cristobalite, new dense silica polymorph in the Martian Shergotty meteorite, and controversial post-stishovite phas...
Evidence that crystalline silica is associated with an increased rate of lung cancer led the International Agency for Research on Cancer to conclude in 1997 that crystalline silica is a known human carcinogen. In Israel too, crystalline silica is considered as such. The decision raised a debate in the scientific arena, and a few scientists have questioned the basis upon which causality was dete...
Urogenital myiasis caused by Psychoda spp. involving human are very rare and present with unusual symptoms. Larvae belonging to Psychoda sp. (Diptera: Psychodidae) were found in the urogenital tract of a 9-year-old girl, who lives in Tajoura, Libya, and had suffered from genital pruritus and moving larvae in urine. This is the first record of such case in Libya.
1 The Faculty of Medical Sciences, University of Kragujevac, Kragujevac, Serbia, 2 Department of Health Services Research, CAPHRI, Faculty of Health, Medicine and Life Sciences, Maastricht University Medical Centre, Maastricht University, Maastricht, Netherlands, 3 Top Institute Evidence-Based Education Research (TIER), Maastricht University, Maastricht, Netherlands, 4 Faculty of Social and Pol...
Many drugs exist in crystalline solid form due to reasons of stability and ease of handling during the various stages of drug development. Crystalline solids can exist in the form of polymorphs, solvates or hydrates. Phase transitions such as polymorph inter-conversion, formation of hydrates, desolvation of solvates, and conversion of the crystalline to amorphous form may occur during various p...
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