a new polymorph crystalline silica composition having uniform pore dimensions were synthesized by calcining a crystalline hydrated alkyl-ammonium silicate. the pore dimensions approximately were 6 angstrom for silicalite-1 and 11 angstrom for silicalite-2 units. the silicalite-1 was prepared hydrothermally at a ph of about 10 from a reaction mixture consist of water, amorphous silica and a quat...

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background: the term crystallized silica refers to the crystallized form of sio 2 and quartz, the most frequency composition in the earth’s crust that can cause silicosis and lung cancer through occupational exposure and inhalation of its large quantities. methods: occupational exposure of workers in pakdasht, iran, in 2011 was investigated in four different casting processes in small foundries...

an aqueous extract of pimpinella anisum was used for green synthesis of silver nanoparticles by bio reduction of an aqueous solution of silver nitrate. silver nanoparticles were characterized by uv–vis spectrometry, fourier transform infrared spectroscopy (ftir), x-ray diffraction (xrd) analysis, scanning electron microscopy (sem) and energy-dispersive x-ray analysis (edax). the increase in abs...

We argue that the current ethical and regulatory framework for permissible risk levels in pediatric research can be helpfully understood in terms of children's moral right to adequate protection from harm. Our analysis provides a rationale for what we propose as the highest level of permissible risk in pediatric research without the prospect of direct benefit: what we call "relatively minor" ri...

Clinical research has demonstrated the the continuous decline of the contrast sensitivity with age results from increasing spherical aberration of the human crystalline lens. Replacing the crystalline lens with appropriate modeled pseudophakic lens can provide superior contrast sensitivity and functional vision. As advances in the technology allow cataract and refractive surgeons to address hig...