Using density-functional theory, we computed all the independent elastic constants of coesite, a high-pressure polymorph of silica, as functions of pressure up to 15 GPa. The results are in good agreement with experimental measurements under ambient conditions. Also, the predicted pressure-dependent elastic properties are consistent with x-ray data in the literature concerning lattice strains a...

Silica aerogels are porous and extremely lightweight nano-materials shows interesting properties. These materials, because of biocompatibility, non-harmful to the body and special physical characteristics such as large surface area and low density have great potential for use in a drug delivery system (DDS). The focus of this study is the evaluation of the effects of silica aerogels on improvin...

Polymorphism, which describes the occurrence of different lattice structures in a crystalline material, is a critical phenomenon in materials science and condensed matter physics. Recently, configuration disorder was compositionally engineered into single lattices, leading to the discovery of high-entropy alloys and high-entropy oxides. For these novel entropy-stabilized forms of crystalline ma...

Silica-clad optical fibers comprising a core of crystalline germanium were drawn using a molten core technique. With respect to previous fibers drawn using a borosilicate cladding, the present fibers exhibit negligible oxygen despite being fabricated at more than twice the melting point of the germanium. The counterintuitive result of less oxygen when the fiber is drawn at a higher temperatures...

Amorphous intermediate phases are vital precursors in the crystallization of many biogenic minerals. While inherent short-range orders have been found in amorphous calcium carbonates (ACCs) relating to different crystalline forms, it has never been clarified experimentally whether such orders already exist in very small clusters less than 2 nm in size. Here, we studied the stability and structu...

This study investigated occupational exposure to silica dust of 48 workers in stone cutting, glass making, ceramic, and sand blasting plants in the north of Iran. Samples were collected from the breathing zone using a personal sampling pump and a size-selective cyclone. Sample filters and blanks were analysed using infrared spectroscopy. The mean sampling period was 4.83 h. Mean exposure of wor...

The extra demand imposed upon the Libyan health services during and after the Libyan revolution in 2011 led the ailing health systems to collapse. To start the planning process to re-engineer the health sector, the Libyan Ministry of Health in collaboration with the World Health Organisation (WHO) and other international experts in the field sponsored the National Health Systems Conference in T...

PURPOSE There is a substantial body of research that utilizes saliva cortisol levels to examine wartime stress; however, there is a paucity of literature that utilizes hair cortisol levels, which allows for long-term assessment of chronic stress, to investigate the stress of war. The present study aimed to evaluate changes in hair cortisol concentrations before, during, and after the 2011 Libya...

A quantitative determinants-of-exposure analysis of respirable crystalline silica (RCS) levels in the construction industry was performed using a database compiled from an extensive literature review. Statistical models were developed to predict work-shift exposure levels by trade. Monte Carlo simulation was used to recreate exposures derived from summarized measurements which were combined wit...

During the last few decades most developing countries have experienced a rapid growth in population which has resulted in a rapid urbanisation in the form of an expansion of existing towns, coupled with an increasing dependence upon developed countries for implementation of new housing programmes. The purpose of this study is to point out the problems of public housing, to identify the relation...