مسعود فرجی

A microbial fuel cell (MFC) is a device that converts chemical energy into electrical energy through the catalytic processes of microorganisms. In this study, a graphite-based flexible film was obtained by adding of zinc powder to a mixture of multi walled carbon nanotubes-graphite powder-polyvinyl chloride (PVC) and then selectively replacing of palladium (Pd) with Zn in a solution containing PdCl2. Surface morphology studies showed that the flexible film has a porous structure, where palladium and carbon nanotubes as uniform conduction channels are present in composite of the film. Electrochemical studies also showed that porous Pd/MWCNTs-Graphite-PVC film as a cathode in MFC at 22-ohm resistance has a current density and power density of 568 mA/m2 and 18500 µW/m2, respectively (compared to 191 mA/m2 and 810 µW/m2 for Pt foil), showing excellent electrochemical activity of the modified film for O2 reduction. Improved electrocatalytic behavior of the modified film can be attributed to porous structure of film and synergistic effect between CNTs and palladium. The method presented in this research can be employed as a favorite method for preparing of suitable electrocatalysts based on commercial graphite powder in the microbial fuel cells.

A microbial fuel cell (MFC) is a device that converts chemical energy into electrical energy through the catalytic processes of microorganisms. In this study, flexible and porous WO3/CNTs-Graphite-PVC film was fabricated through uniform adding of Zn powder into matrix of carbon nanotubes-graphite- Polyvinyl Chloride) PVC (film followed by selective dissolving of Zn from the film structure in acidic solution and finally electrodeposition of WO3 (Tungsten trioxide) into previously porous CNTs-Graphite-PVC film. Surface morphology studies showed that the flexible film has rough and porous structure and carbon nanotubes are uniformly present as electron conduction channels within the composite film. Studies also showed that porous WO3/MWCNTs-Graphite-PVC film as a bioanode in MFC at resistance of 1000 ohms and current density of 900 mA/m2 has a power density of 324 mW/m2. The method presented in this research can be used as a suitable method for preparing of suitable electrocatalysts based on commercial graphite powder in microbial fuel cells.

A novel kind of AgNPs-MWCNTs/TiO2 nanotubes/Ti electrocatalyst for the electrocatalytic oxidation of glycerol was fabricated via electrodeposition of Ag nanoparticles and functionalized multi walled carbon nanotubes on previously formed TiO2 nanotubes/Ti electrode. The morphology studies showed that AgNPs-MWCNTs nanocomposites have dendritic structures, where Ag nanoparticles are uniformly dispersed on the surface of MWCNTs. Electrochemical investigation exhibited that the AgNPs-MWCNTs/TiO2NTs/Ti show much higher peak current density and lower charge transfer resistance towards the glycerol oxidation than AgNPs/TiO2NTs/Ti electrode, indicating good electrocatalytic performance and kinetic reversibility of the AgNPs-MWCNTs/TiO2NTs/Ti electrocatalysts. The improved electrocatalytic activity of modified electrode is originated from the synergetic effect of AgNPs-MWCNTs, the unique nanostructure and large surface area which can provide more active sites to catalyze the glycerol oxidation.

WO3-NPs/TiO2NTs/Ti plates with high surface area and good catalytic characteristics were fabricated by electrochemical loading of WO3 nanoparticels onto the previously formed highly oriented TiO2 nanotubes/Ti plates. These plates were characterized by X-ray diffraction, electrochemical impedance spectroscopy, scanning electron microscopy and UV–visible spectroscopy. The morphological studies showed that the WO3 nanoparticels has been uniformly deposited onto the TiO2 nanotubes. The modified plates efficiently catalyzed the activation of H2O2 to generate hydroxyl radicals, causing the fast degradation of methylene blue (MB) at room temperature. Almost complete oxidative degradation of MB was obtained after 60 min in presence of H2O2 as a green oxidant. The high activity of the WO3-NPs/TiO2-nanotube/Ti plate was attributed to excellent mesoporous properties of the TiO2-nanotube/Ti plate as substrate and nano size of the WO3 with more surface sites exposed for dye degradation reaction. Furthermore, the WO3-NPs/TiO2-NTs/Ti plates are reasonably stable and could be recycled for several runs.

Co3O4/MWCNT/TiO2NTs/Ti electrodes were prepared by Electrdeposition of Multe-Walled Carbon Nano Tubes-Co3O4 nanocomposite onto previously formed TiO2 nanotubes. Microstructure studies show that Co3O4/MWCNT having high surface area has been deposited onto the TiO2NTs arrays. The capacitive behavior of the new electrode was investigated by cyclic voltammetry (CV), charge–discharge test and electrochemical impedance analysis (EIS). The electrochemical data demonstrated that the electrodes displayed high specific capacitance compared to Co3O4/TiO2NTs/Ti. The EIS studies showed that MWCNTs in the nanocomposite can significantly improve the parameters effectively influencing the capacitive behavior such as ohmic resistance (Rs), charge transfer resistance (Rct) and faradaic pseudocapacitance element (CPE).

Liquid curd is one of the milk byproducts and a rich source of protein among the food products. So it is a suitable environment for the growth and reproduction of different microorganisms. According to the harmful effects of chemical preservatives, the need for studies on antimicrobial effects of natural preservatives on the growth of microorganisms in food and laboratory models are growing.
This study includes extraction and determination of chemical composition of shallot (Allium Hirtifolium) and evaluation of their antibacterial effects against Staphylococcus aureus and Clostridium botulinum. First liquid curds containing 0.5%, 0.75%, 1% and 2% shallots extract were prepared. Then each sample was contaminated individually with Staphylococcus aureus (107 cfu/ml) and Clostridium botulinum (107 cfu/ml) and stored at 4ºC refrigerator for 21 days. Sampling of curd took place on day zero, seven, fourteen and twenty-one.
The results of this study showed that the pH of liquid curd was considerably reduced during the storage time. Also the population of Staphylococcus aureus decreased more quickly than Clostridium botulinum. After 21 days of storage, there was no sign of survival of Staphylococcus aureus.
The sample containing 1% shallot (Allium Hirtifolium) extract was preferred in both terms of reducing microbial growth and suitable sensory properties.
as the sample with 25% triticale flour 0.6% tragacanth gum.
Replacing 25% of wheat flour with triticale flour, (Sanabad varieties) is recommended as the first edible cultivars in bread production in Iran with gum tragacanth at 0.6 % for strengthening and improvements of the gluten network in bread.

Simulation of fluid flow within tunnel is an appropriate and relatively cheap way to investigate the spreading of the pollutants and the efficiency of tunnel ventilation system. In this research, the tunnel of Tehran-Tabriz line is studied from this aspect. This tunnel is 8 km long and 32 m width, and the locmomotive ER24PC passes from it. Ventilation of this tunnel is of great importance because of considerable length of the tunnel with 4 parallel lines in urban area and because of passage of the old diesel locomotives through it. Fluent software is used for numerical analysis and modeling of a length of 200 m of the tunnel. The species of each gases in combustion product mixture of ER24PC locomotive are obtained using emission standard EU III A. The molar ratio of pollutants in the exhaust of the locomotive is calculated using equilibrium equation of combustion, and then, is entered to the non-premixed combustion toolbox of the software to specify the volume fraction. In the critical case, two trains with a speed of 50 km/hr moving toward each other in the parallel lines are considered. The simulation is carried out by using dynamic mesh and UDF motion code. The simulation is validated by experimental work reported in references. The performance of ventilation system, temperature distribution along the tunnel and the effect of the motion of the train on spreading pollutants are investigated.
Summary In this study, simulation of moving ER24PC (Siemens) locomotive in three dimensional (3D ) mode is made by using dynamic mesh in the Fluent software. The modeling of moving locomotives is a new idea in the field of tunnel ventilation. Thus, the distribution of outlet pollutants is investigated in both length and cross sections of the tunnel due to the motion of the train, and also, the effect of the motion of the train on spreading CO and Nox is investigated.
Introduction Ventilation of tunnels is important in two applications of traffic and fire mode. In recent years, some disasters due to tunnel firing, for example in Baku or Daegu metro, have occurred that show the importance of fire and smoke ventilation in tunnels. The initiation of fire in tunnel produces a huge amount of smoke, which moves to the ceiling due to the buoyancy effect, and spread out in both sides. The task of tunnel ventilation system in this critical mode is to push the smoke into one side, and make a safe passage for passenger escape or rescue team.
Methodology and Approaches In this study, locomotive emissions are simulated as a moving point and as a result, pollutants spread in 3D space. The combustion products of the locomotive are obtained by considering the MTU engine exhaust emissions and using Emission standard EU III A. The volume fraction of each pollutant is calculated from the equilibrium equation of combustion and is entered into the non-premixed combustion toolbox of the Fluent software. The moving train is modeled using dynamic mesh and employing UDF motion code. The velocity of the trian is considered to be 50 km/hr and two crossings against train are considered as a critical mode.
Results and Conclusions In the case of no forced ventilation in tunnels, it can be seen that the motion of trains induces air flow passing above the train that causes the spread of smoke behind of the train. The maximum temperature and concentrations of pollutants happen above the chimney of the locomotive, and decrease toward the start point of motion. The temperature and concentration values of pollutants in the tunnel cross-section are independent when the incoming trains are at the near wall line or center line. The results also show that the concentrations of toxic gases from the ER24PC locomotive do not reach to the critical values as long as the locomotive in the tunnel is moved.