Sharif Digital Repository

Yttrium Aluminum Garnet powders possessing controlled size distribution has found applications in production of transparent ceramics, phosphors, laser host materials and composites. Sol-Gel Combustion process is one of the versatile methods to produce nanometeric garnet powders. This procedure is based on combustion of a concentrated gel of metal salts and fuel in an exothermic reaction which leads to nanoparticles formation. pH value of solution and employed fuel system strongly affect production quality and single phase nanopowder can be synthesized by well monitoring these parameters. In this study nanocrystalline Yttrium Aluminum Garnet powders was Synthesized via sol-gel combustion... 

TiO2 is one of the most frequently used photocatalyst materials. Porous TiO2 nanostructure has drawn much attention recently due to high decomposition rate of organic pollutants. In this thesis, TiO2 nanoparticles were synthesized via sol-gel method and were coated on cotton and jute fiber separately; besides, the impregnated fibers were heat treated to eliminate cellulose. Titanium tetraisopropoxide (TTIP) was used as a precursor and two solutions, acidic and alcoholic, were used as the primary solutions for synthesis. In acidic solution, the crystalline phase and size distribution of TiO2 nanoparticles were evaluated with changing pH.Then, the appropriate pH was chosen for coating. In... 

In this project, function of anaerobic digestion of organic waste in liquid phase and treating the following sewage in biologic tower(trickling filter) has been investigated in an experimental process. Solid waste were supplied from sharif university restaurant and after weighting and classification is added to tanks which filled by 40% sludge and 60% water. For controlling the function of biologic tower, a control reactor were used. Retention time for digestion of solid waste is 40 day. First solid loading was 500g and 75g organic waste in main & control reactor equal to 5(kg solid waste)/( m^3.reactor.day) 1.3(kg TS)/( m^3.reactor.day) and were doubled in second loading. It seems that... 

Combustion synthesis is the best and most effective method for producing ceramic nano-composites which is also a simple and economic way of producing very fine powders with high purity. In this method, a series of combustion reactions named aqueous combustion analysis are used for producing single-phase and nano-composite products ,in which the heat produced in reactions are used for completing the phase . several chemical substances such as glycine ,urea ,ammonium acetate and others are used as combustion agents. In order to obtain optimized nano fuel, we produced alumina powder with multiple combustion percentages and composition of 25%moli ammonium acetate (AA) with 75%moli urea was... 

Proteins are of fundamental importance for life on Earth and participate in virtually every process within cells. The function of a protein depends on its three dimensional structure. If this is disrupted, the protein loses its biological activity. In addition to temperature, pressure and ionic strength, pH is also an important factor that affects the configuration of proteins. Proteins contain acidic and basic residues. Variations in pH lead to changes in distribution of atomic charge, which in turn affect the stability and function of proteins. Protein folding occurs in a specific pH range, a deviation from which may facilitate misfolding or Amyloid aggregation. It is therefore necessary... 

Particle reinforced aluminum matrix composites have considerable attraction in automotive and aerospace industries due to their special properties as light weight, high ratio of strength/density, improved elastic modulus, low coefficient of thermal expansion and high wear and corrosion resistance. Among the production processes of metal matrix composites, accumulative roll bonding process has particular importance due to producing ultrafine grained composite sheets. However, uncontrolled and undesired agglomeration of particles is the main problem in producing these composites. In this research, the Al2O3 and SiC nanoparticles were electrostatically stabilized against agglomeration by... 

Microbial electrolysis cell is a novel technology for hydrogen production. The biggest challenges for this new technology are low rate of hydrogen production and high investment cost.
In this research, catholite condition was investigated for increasing the rate of hydrogen production. Low price stainless steel was used as cathode electrod. The microbial electrolysis cell operated applying 1.3 v external voltage. Basic pH was found to be the best condition for maximum rate of hydrogen production, where the average rate of hydrogen production was 100.006 1.866 L/m3.d. However, the hydrogen production rate for the acidic and neutral cathodic condition, were 92.89 1.13 and 91.845 1.485... 

In this research, we have studied optimization of culture medium and process factors for high alkaline protease production from Bacillus subtilis ATCC 6633 for detergent usage. Five parameter soy bean meal, initial pH, agitation rate, MgSO4, CaCl2 were selected for more studies. At first, one-factor-at-a-time method was applied to investigate effect of each factor separately. Then, optimum condition for maximum protease production was achieved using Minitab software Box-benhnken procedure. According to results, high protease production was seen in soy bean meal, 35 (g/L); MgSO4, 1 (g/L); CaCl2 , 1.5 (g/L); initial pH, 7; agitation rate, 150; inoculum ratio, 12% (v/v). The activity of the...