The aim of this study was to investigate the effect of coating Populus nigra with silica nanoparticles on some performance parameters. Wood samples of P. nigrawere were coated with a combination of silica nanoparticles (3%, 5% and 7%) and zycosil by spin coating method and the obtained results were compared with controls of A. alba and P. nigra. Structural properties of wood samples were investigated by SEM and FTIR tests. Performance properties of wood samples, including water absorption, contact angle and density were investigated. The results showed formation bonds between silica nanoparticles and zycosil. Coating wood samples with silica nanoparticles in the concentrations of 5% and 7% in combination with zycosil decreased water absorption compared to P. nigra control (P<0. 05). The wood samples coated with nanosilica and zycosil had a higher contact angle and density compared to P. nigracontrol (P<0. 05).

In this study, the performance of direct absorption solar collector is experimentally investigated using Fe3O4/Silica hybrid nanofluid based on deionized water. First, stability of prepared nanofluids is considered using spectral absorbency method. Then, spectrophotometry method is used for measuring optical properties of nanofluids. A prototype of this new type of collector was built with applicability for solar water heating systems. The procedure of EN 12975-2 standard was used for testing the thermal performance of the collector. Results show that collector efficiency is enhanced by nanofluid concentration, so that collector maximum efficiency is 73.9%, 79.8% and 83.7%using nanofluid with concentration of 500 ppm, 1000 ppm and 2000 ppm, respec/tively. This vaule is 63% using the base fluid as working fluid. Regarding very low volume fractions of nanofluids used in direct absorption solar collectors, the viscosity of the base fluid experience insignificant increase, therefore, pumping power will not increase significsantly. Such increase in efficiency show that direct absorption solar collector performance using hybrid nanofluid is much better than that of using the water at the same operating conditions. Application of stable hybrid nanofluid results in higher conversion efficiency of solar energy to useful energy.

Introduction: Dimensional changes in acrylic patterns during laboratory process to fabricate casting are an important issue which could lead to many clinical consequences. Microleakage, lack of retention and fitness are few of problems which could be predicted in the case of dimensional changes in acrylic patterns. So, investigating the factors which could minimize the dimensional change is necessary. This study compares how different proportions of silica-sol and distilled water affect the dimensional changes in castings.Methods: This study was an experimental study wherein 30 specimens of acrylic patterns (Duralay) with similar dimensions were prepared and equally divided in five different groups and studied. Using extensiometer digital machine, the acrylic patterns were measured at three portions (length, coronal diameter and apical diameter) with accuracy of 10 microns.Results: 1- The mean average of casting post length compared to changed acrylic patterns was statistically significant in pure distilled water group only.2- The mean average of changes in casting coronal diameter did not demonstrate any significant differences compared to acrylic patterns.3- The mean average of changes in casting post apical diameter compared to acrylic patterns using pure distilled water was significant.Conclusion: Because the least value in dimensional change was seen in 2/1, 3/1 ratio of silica-sol and distilled water, these ratios are recommended in fabrication of casting posts in order to have maximum accuracy and minimum micro leakage while building crowns and bridges.

Occupational exposure to heavy metals, organic solvents and silica is associated with a variety of renal manifestations. Improved understanding of occupational renal disease provides insight into environmental renal disease, improving knowledge of disease pathogenesis. Silica (SiO2) is an abundant mineral found in sand, rock, and soil. Workers exposed to silica include sandblasters, miners, quarry workers, masons, ceramic workers and glass manufacturers. Newcases of silicosisper year have been estimated in the USto be 3600-7300. Exposure to silica has been associated with tubulointerstitial disease, immune-mediated multisystem disease, chronic kidney disease and end-stage renal disease. A rare syndrome of painful, nodular skin lesions has been described in dialysis patients with excessive levels of silicon. Balkan endemic nephropathy is postulated to be due to chronic intoxication with drinking water polluted by silicates released during soil erosion. The mechanism of silica nephrotoxicity is thought to be through direct nephrotoxicity, as well as silica-induced autoimmune diseases such as scleroderma and systemic lupus erythematosus. The renal histopathology varies from focal to crescentic and necrotizing glomerulonephritis with aneurysm formation suggestive of polyarteritis nodosa. The treatment for silica nephrotoxicity is non-specific and depends on the mechanism and stage of the disease. It is quite clear that further research is needed, particularly to elucidate the pathogenesis of silica nephropathy. Considering the importance of diagnosing exposure-related renal disease at early stages, it is imperative to obtain a thorough occupational history in all patients with renal disease, with particular emphasis on exposure to silica, heavy metals, and solvents.

Recycling and reusing of catalyst is an important factor to produce capable and low cast catalysts. Silica coated magnetic nanoparticles (Fe3O4/SiO2) were synthesized via a simple sol-gel method with the aid of sonication. Fe3O4 nanoparticles. After that a layer of TiO2 was constricted by hydrolyze and condensation of Teteranormalbuthyltitanate to produce Fe3O4/SiO2/TiO2 nanocompsite. As-synthesized nanparticles were characterized with X-Ray powder Diffraction, Fourier-Transform-Infrarotspektrometer, Transition Electron Microscopy and Scanning Electron Microscopy. In this study, a new kind of Fe3O4/SiO2/TiO2 photocatalyst was prepared with the purpose of using light and inhibiting the recombination of electrons and holes. In situ treatment of Rhdamine B in water was performed using this Fe3O4/SiO2/TiO2 photocatalyst. The purpose of this research was to provide a new method and the basic data for the removal of organic pollutants in water. Fe3O4/SiO2/ TiO2 nanocomposite showed enhanced photocatalytic properties as evidenced by the enhanced photodegradation of Rhodamine B under ultra violet light irradiation.