Sharif Digital Repository

polyamides have found great attractions in wide variety of applications due to their desirable mechanical and tribological properties and appropriate processability. Pure polymers are not suitable for this kind of application due to their low mechanical strength. High strength materials are needed for abrasive applications. Polytetrafluoroethylene (PTFE) is one of the most popular materials for abrasive applications. In this study the effect of PTFE and surface modification on PA/PTFE composite properties is investigated. duo to modification of PTFE powder, PTFE is exposed to sodium naphtalenide (Na/naphtha) etchant so as to deflurinate the surface for obtaining carbonyl, carboxyl and... 

This study focused on the tolerance of fungi strains including Aspergillus niger, Aspergillus foetidus and Penicillium for different metals (Ni, Co, Mo, V, Mn, Mg, Fe, W and Zn ). Then Aspergillus niger was exposed to mixture of Mo, V and Mn (at a mass ratio of 1:2:6 as approximately present in the spent refinery processing catalyst). The degree of tolerance was measured from the growth rate in the presence of various metals and compared to a control which contained no metals. Effect of type of strains, type of metal and metal concentration on adaptive tolerance of fungus was evaluated. Adaptation experiments with single metals showed Aspergillus niger tolerated up to 1000 mg/l Ni, Zn, 1500... 

Acidophilic microorganisms such as Thiobacillus ferrooxidans have the capability to carry out process of biorecovery of heavy metals. Its principle is the microbial production of the sulphuric acid and simultaneous recovery of metals. Acidithiobacillus ferrooxidans derives the energy for their metabolism from ferrous iron oxidation process which can be affected by the presence of heavy metals in the medium. In this study the ability of Acidithiobacillus ferrooxidans, on the biorecovery of heavy metals in shake flask has been investigated The adaptation of the Acidithiobacillus ferrooxidans to a kind of heavy metal such as Nickel, Cobalt, Vanadium, Molybdenum, Tungsten and the mixture of the... 

During oil refinement, solid catalysts which contain metals such as aluminum, tungstan, molybdenum and nickel are highly used. Following several times reductions and re-applications, their activity potentiality is decreased in a such a way that they can not be re-used., as a result of which they are treated as solid waste. Based on natural potentiality, microorganisms are defined as convertibles of solid compounds to extractive forms and soluble materials. This project aims at finding other factors that have more impact on biological extraction and determining optimal conditions for biological extraction in order to reach maximum extraction efficiency within discontinuous conditions. The... 

Bio-desulfurization is the sulfur removal process from organosulfur compounds by the action of microorganisms (which are capable of removing sulfur). Too many studies have been carried out in the use of biocatalysts for BDS process. In this project, we have used data obtained from a previous experiment in which a trickle bed reactor (diameter: 0.066 m, height: 0.6 m) and a Rhodococcus sp. 12891 starin immobilized on bed particles are used to produce diesel with low sulfur content. Sulfur concentration of inlet diesel is between 200ppm to 540 ppm. parameters of process are recycle Ratio , volumetric flow rate and sulfur content of inlet diesel.
A mathematical model for trickle bed... 

In this project, energy in form of electricity and hydrogen was produced in microbial fuel cell and microbial electrolysis cell respectively. For reducing costs, a stainless steel mesh with graphite coating was used as anode electode. Also for increasing efficiency, anode was positioned in cells in a spiral mode. Efficiency of cells was investigated in batch and continuous mode. In this research, dairy wastewater was used as substrate.This wastewater not only has severe emissions, but also is high energy content. In the field of dairy wastewater treatment and hydrogen production in an microbial electrolysis cell wasn’t observed any article.At the first, wastewater was treated in two... 

This study is a report on the fabrication of a novel single-chamber micro-structure microbial fuel cell consisting of spiral anode chamber. A 3×3 cm plexiglass plate with 1 mm thickness was used as main body. A spiral microchannel (1 mm in width and 226 mm in length) was cut using a laser beam as an anodic compartment. Two types of microbial fuel cells with the same anode electrode (stainless steel mesh) and different cathode electrodes (stainless steel mesh and carbon cloth) were constructed in order to investigate the effect of cathode electrode material on microbial fuel cell performance. In both batch and continuous mode, higher power density was obtained by microbial fuel cell with... 

Accumulation of electronic wastes in the environment is one of the recent ecological problems. This type of wastes contain metallic and non-metallic elements which can contaminate the environment. On the other hand due to the high volume of precious and basic metals within e-waste, it could be considered as a secondary resource. Bioleaching is a suitable method for the recovery of metals from e-waste which, on the contrary to the conventional recycling methods in the industry, is both economically and ecologically efficient. The aim of this research is the isolation of native micro-organism and evaluating its ability in recovering copper from a mixture of computer, cellphone, fax and copy... 

In this research, different methods of coating polyaniline on the anode electrode and its performance in a microbial fuel cell, and a chemical method for making polyaniline / graphene catalyst on a cathode electrode and its performance in microbial electrolysis cell electrode were investigated. There are two main goals in this study. First, the production of polyaniline and the comparison of the surface morphology of this fiber with other forms of polyaniline on the surface of the electrode and its effect on the performance of the microbial fuel cell and the second, the production of polyaniline / graphene catalyst in the cathode electrode and its comparison with the platinum catalyst in the... 

Among all electornical wastes, printed circuit boards (PCBs) of mobile phones and computers has more share than other e-wastes. E-wastes contains toxic and maybe worthable metals like copper, nickel, gold, silvet and etc. In this project, ability of Penicillin Simplicissimum in bio-leaching of copper and nickle in mobile phones PCBs, is studied. Daily production of this kind of e-wastes, requires an industrialized and economical method to help the environment. At the first step of this project, the fungi was adapted to e-waste. Then, optimization of pH and number of spores in inoculum of bioleaching by Penicillin Simplicissimum in non-conventional mediums (sugar, cheese water and molasses)... 

Polychlorinated biphenyls are a group of hydrocarbons that are composed of two benzene rings and chlorine admixture on it. Due to their special properties, these materials were added to oils for years to improve their properties. These compounds have many industrial applications in various industries, such as the production of fluorescent lamps, adhesives, dyes, and especially as a cooling and insulating liquid as the Askarel oil in power transformers. Due to the properties of these compounds, which include stability and bioaccumulation in fatty tissues, the wide use of these substances causes environmental contamination and leads to a variety of cancerous diseases. Among the cleaning... 

Given the complex structure of electronic waste and the difficulty of recycling it by traditional methods, the focus is mainly on biohydrometallurgy method, and in particular on bioleaching. To recover metals, various microorganisms are utilized in this method. In light of previous studies, cyanogenic bacteria have been widely used for the extraction of basic and precious metals. Among the species, indigenous microorganisms have a higher ability to resist toxic environments in the bioleaching of metals due to their adaptation by rapid changes in their metabolic system over time. The main objective of this study is to isolate indigenous microorganisms from electronic waste landfill for their... 

The presence of highly toxic cyanides in the effluent of coke oven of steel industries is considered as a critical problem. Owing to high levels of toxicity, control and removal of cyanide are of great importance in this industry. Biological removal of cyanides by indigenous microorganisms offers inexpensive, safe and environmentally compatible option in comparison with chemical and physical methods. The present study primarily focused on the isolation and purification of the microorganisms which utilize cyanide as the sole source of Nitrogen in alkaline conditions. The isolated bacterial strains were investigated through variety of bacteriological and biochemical reactions as well as... 

Microbial fuel cell is one of the new technologies in the field of power generation from the organic energy resource. The fuel cell system in a process similar to chemical fuel cell generate electrical energy through oxidation of organic composition by uses of electrogenic microorganisms as biocatalyst. In this study the main object is providing a comprehensive mathematical model for the fuel cell system in micro-liter size. To achieve this purpose, we start to investigate properties of fuel cell system in this size. And according to the geometry of system we choose chemotactic equation for estimating hydrodynamic behavior of microorganism and using combination of conductive base and... 

The first attempt of this study was theoretical and experimental investigations of bioelectrochemical processes in microfluidic systems. Besides, novel applications of this technology as a powerful platform for maximum usage of bioenergy were introduced. The feasibility of a microfluidic microbial fuel cell (MFC) as an efficient power generator for production of bioelectricity for implantable medical devices (IMDs) and fabrication of microfluidic microbial electrolysis cell (MEC) for hydrogen medicine were investigated. For the glucose-fed microfluidic MFC, the maximum power density of 5.2 µW cm-2 obtained in this study is 13 fold greater than the power density reported previously for... 

The most important desire of all researchers in food industry is decreasing the contamination of foods and increasing their shelf life. Due to harmfulness of chemical preservatives their use has been limited and therefore natural antimicrobials have been demanded. Recently spices have been noticed as natural antimicrobial agents. Sumac is a kind of spice which has antibacterial and antioxidant activities.The aim of this project is to investigate effects of water and alcoholic extracts of Iranian red sumac comparatively on three gram positive bacteria (Bacillus coagulans , Bacillus subtilis, Staphylococcus aureus) and one gram negative (Escherichia coli) by well and disk diffusion method.... 

With the current demands in alternative methods of energy production and increased utilization of existing energy sources, microbial fuel cells have become an important field of research. In a microbial fuel cell, organic and inorganic compounds can be oxidized by microbial catabolism at the anode to generate direct electricity. A kind of microbial fuel cell (MFC) is sediment microbial fuel cell (SMFC) consists of an anode electrode embedded in the anaerobic sediment and a cathode electrode suspended in the overlying aerobic water. microorganisms produce electrons by oxidation of organic or inorganic compounds in the sediment at anode electrode, while oxygen is reduced in the water by... 

Microcarriers (MCs) are an attractive technology with various applications in tissue engineering. In this study, chitosan/gelatin MCs were fabricated with blends of different ratio of chitosan/gelatin, by using a setup containing high voltage electrostatic field and syringe pump. Optimization of blend ratio, voltage and syringe pump flow carried out by the “Design expert” software leads to fabrication of MCs with constant diameter while having various elasticity. Mechanical strength and elasticity of MCs were determined. Human umbilical cord mesenchymal stem cells (hUCMSCs) were cultured on MCs dynamically by using mini-rocher in an incubator. Cells adhesion on MCs were successfully shown by... 

In this study, simultaneous production of bioelectricity and algal biomass, wastewater treatment and carbon dioxide capturing in an Algal-Cathode Photosynthetic Microbial Fuel Cell has been evaluated. The performance of the system under different light intensity (3500, 5000, 7000 and 10000 lux) and also different light:dark regime (24:00, 12:12 and 8:16 hour) has been studied. The results show that, light intensity has direct effects on performance of Photosynthetic Microbial Fuel Cell (PMFC) with changing dissolved oxygen in biological cathode. So, the PMFC can reach power density of 125.96 mW/m3 with optimized light intensity of 5000 lux and simultaneously columbic efficiency and COD...