Sharif Digital Repository

The air cathode of li-air batteries plays a pivotal role in the overall performance of Li-air batteries. Graphene-based cathodes have been investigated as cathode catalysts for lithium-air batteries due to their extraordinary potential for accelerating and facilitating oxygen reduction reaction (ORR).In this study graphene oxide have been synthesized via modified Hummers’ method. Consequently, the as obtained graphene oxide have been reduced using chemical, electrochemical, and hydrothermal methods. Results of elechtrochemical evaluations demonstrate that the graphene oxide reduced via hydrothermal method possesses the most positive ORR onset potential (+0.55V vs SHE) among the other samples... 

Despite the increase in the number of cardiovascular diseases worldwide, the number of new drugs to treat these diseases has been decreasing in the last decade. Current preclinical drug evaluation strategies, which use cell cultures and oversimplified animal models, cannot meet the growing demand for new and effective drugs. In the last decade, the development of microfluidic bioreactors and organ-on-chip systems to improve the drug screening process has been increasing significantly. These systems have shown many advantages over previous preclinical models. Despite all these advantages, keeping the oxygen concentration at the optimal physiological level in microfluidic systems has its own... 

Designing a system based on 2 to 5 MeV electron accelerators for X radiation of urban waste.Nowadays , the use of ionizing radiation in two cases of treatment and removal of contaminants in the waste including; 1) Pathological hospital waste 2) leachate from buried urban waste, which is studied and examined in this project. Buried urban wastes begin to break down under aerobic and anaerobic processes, and as long as the materials are not changed into sustainable materials, these processes will continue and results in landfill gas and leachate. Gas is produce due to anaerobic processes and leachate which is produced through water infiltration (atmospheric precipitation) in the landfill or... 

The effect of the combination of MBR and MBBR systems to enhance the efficiency of water treatment plants has been studied. In this study, by embedding a UASB reactor in the presence of packing, as anoxic, two MBBR reactors as a single aerobic treatment and a MBR reactor once with and once without packing as the final purification tried to remove pollutants from artificial drainage and extend the life of the membrane system is designed to convey the wastewater treatment and irrigation is its quality standards functionality and the quality of its wastewater treatment standards for agricultural irrigation. Studied pollutants include COD, ammonia, nitrate, nitrite and phosphate. membrane... 

Pharmaceutical waste has attracted considerable attention, in the Past two decades. These pollutants had not previously been detected in the environment. In fact, the concentration of pharmaceuticals became a matter of concern after the increase in the production and consumption of drugs. Nowadays, considering their higher consumption and more developed detection technologies, they are found in waste water, treated water, rivers, etc. The purpose of this research is to study treatment of a Synthetic waste water contaminated by Diclofenac and Ibuprofen in a Moving Bed Biofilm Reactor. An aerobic Moving Bed Biofilm Reactor (MBBR) with the volume of 8.5 liters and Kaldness packing filling ratio... 

Biological treatment is an essential part of wastewater treatment. One of the major problems of the biological treatment systems is a solid separation. Filamentous bulking is a type of solid separation problem that settled sludge volume and the turbidity of the effluent will be increase in bulking condition. The presence of excessive Filamentous bacteria causes filamentous bulking. In this thesis, filamentous bulking were studied to understand this phenomena better and tried to control that with the different methods. This research was conducted in laboratory scale Sequencing Batch Reactor (SBR), conventional activated sludge and conventional activated sludge with anaerobic selector with... 

The main objective of this research was to evaluate the application of a new strain of Brevundimonas naejangsanensis which is newly identified sulfate-reducing bacteria (SRB), in bioremediation. A laboratory scale packed bed reactor (PBR) was fabricated and operated to study the new bacteria’s feasibility on SO_4^(2-) reduction. The reactor was packed with polyurethane foam cubes and operated under different feeding and operating conditions of HRT, COD/SO_4^(2-) ratio and salinity. A maximum SO_4^(2-) reduction of 73.6% was achieved in the PBR when operated at an HRT of 12 h with SO_4^(2-) concentration of 670 mg/L, COD/SO_4^(2-) ratio of 1 and salinity of 3%. The results show that this... 

Treatment of Wastewater of textile industries has been always challenging due to the high organic matter which is a suitable substrate for the growth of microorganisms. Also, discharge of wastewater into the open water causes water adsorbing more sunlight, raising water temperature and therefor decreasing dissolved oxygen. In addition, the acidity of wastewater decreases the quality of agricultural soil. Among wastewater treatment methods, biological methods are cheaper, environment friendly, and produce less by product. Among all the microorganism responsible for biological treatment, fungi and enzymes are more applicable. Especially white-rot fungi are the most effective microorganism to... 

The use of nanocarriers has been recently considered for targeted drug delivery. In the targeted drug delivery systems, drug is directed to the target tissue and its adverse effects are reduced on the healthy tissues. Graphene oxide and hollow mesoporous carbon nanospheres are two types of the most interesting carbon-based nanocarriers because of their unique properties. Aim of the thesis has been the synthesis of the nanocarriers based-on graphene oxide and hollow mesoporous carbon nanospheres and their surface modifications by magnetic polyamidoamine dendrimer and oxygen-rich polymers such as poly(epichlorohydrin) and hyperbranched polyglycerol. These modifications result in higher... 

The development of alternative energy sources is a prominent area of scientific research. Hydrogen, with its exceptional energy density, has emerged as a particularly promising candidate among these new energy sources. An effective technique for generating hydrogen is through the electrochemical process of water splitting. To enhance this process, it is crucial to investigate the development of electrocatalysts with high electrocatalytic activity. Among the potential options, sulfides of transition metals show promise. An essential difficulty in electrochemical water splitting is the development of a bifunctional catalyst that is both active and stable for both the hydrogen evolution... 

In this study, electrochemical oxygen reduction reaction (ORR) was studied on Cu, Pd, Rh, Pd-Cu and Rh-Cu alloys in alkaline solution. Pd-Cu and Rh-Cu alloys were prepared by electrochemical methods. On copper electrode it is found that direct oxygen reduction is accompanied by the electrochemical reductions of copper oxides. Also, mechanism and kinetics of reaction change as the amount of copper oxides increase on the surface. For electrodeposited alloys, it is indicated that the reactivity of Pd-Cu and Rh-Cu alloys toward oxygen reduction is higher than pure Pd and pure Rh. The maximum reactivity among Pd-Cu alloys is related to the sample with 24.5% copper content while the maximum... 

The bronchial tree consists of two main parts: conducting airways and respiratory airways. Parametric Lindenmayer System (L-System) has been used for modeling of the structure. The conducting airways are divided into two parts: central region consisting of trachea up to segmental bronchi and bronchioles located in the bronchopulmonary segments. The boundary of these segments has been found by image processing techniques. Stochastic Parametric L-system has been used for modeling of acinar region. To find the characteristic properties of conducting airways and respiratory bronchioles, an intelligent method has been developed. The parameters of the model are either age dependent or... 

Water is one of the world’s most valuable resources, yet it is under constant threat due to climate change, explosive population growth, and waste. One of the most promising efforts to stem the global water crisis is river contaminated, water reclamation and reuse. This study was carried out to investigate in the water quality “S. H. C.” using treatment techniques. Research project was to check out which method give maximum removal of TOC, COD and coliform, fecal coliform and TSS where this parameters exceeded the permissible limits and therefore “S. H. C.” water was contaminated by these parameters. After carrying out the study more from 8 month on water treatment "S. H. C." we get the... 

This study deals with the treatment of medium density fiberboard (MDF) effluent aiming at the removal of TSS, COD, BOD and Turbidity by means of soil aquifer treatment (SAT). Removal of parameters were evaluated during transport of MDF effluent under unsaturated flow conditions in 1-m soil (sandy-clay soil) depth. The experimental results showed that the new process with SAT to be very effective. The TSS, COD, BOD and turbidity removal average was about 99%, 30%, 89 and 98.5% at the optimum operation condition, respectively. The SAT should be added before the UASB in order to achieve high removal rate of COD and BOD. The UASB (concentration sludge 40000 mg/l) after SAT treatment MDF... 

Importance: Age related cataract is the major cause of blindness worldwide.in recent years several studies has been done with the aim of understanding the cataract process, but no attempts has been done for simulation and study of the vitreous aging and its effect on cataract.
Objective: To investigation and determination of effective mechanism for increasing oxygen in vitreous humor and simulation the oxygen tension changes with vitreous degeneration with age or vitrectomy.Methods: Effects of changes in chemical composition of vitreous humor with age or vitrectomy on oxygen solubility is studied by thermodynamic relations. The posterior segment of the eye is modeled using transport... 

Electrocoagulation is one of the new methods for water and wastewater treatment that is carried out by electrical current. This method is easily applicable to a variety of wastewater. it is highly efficient in organic matter removal and other toxic are and dangerous pollutants.
This study dealt with diesel and COD removal by Electrocoagulation method. Energy consumption, electricity consumption, and the amount of sludge produced by this method was evaluated. Experiments were conducted in a 2 L reactor, consisting aluminum and iron electrodes.The distance between anode and cathode was 5 cm. To evaluate the efficiency of electrocoagulation method, parameters including: pH, time,... 

Organ-on-chip microfluidic devices create a three-dimensional and dynamic model that allows researchers to model diseases and test different drug candidates. In this regard, using a lung-on-a-chip microfluidic device, Covid-19 disease was numerically modeled. Initially, the distribution of oxygen concentration in the blood and respiratory membrane in the healthy state; when the respiratory membrane is the only barrier between air and blood; was found and observed that in this case, the length that the blood had to travel to reach full saturation was the same in the alveolar capillaries and the lung-on-a-chip microdevice. Then, to simulate the different phases of the disease, the formation of... 

In this study, chitosan-based nanoparticles were prepared due to their biocompatibility, availability, high loading capacity of drug, stimulus responsive behavior and the presence of active functional groups. Chitosan was chemically functionalized with reactive oxygen species (ROS)-responsive moiety to respond to the oxidative stess and endosomal pH in nerve injuries. To prepare nanoparticles, functinalized chitosan ionically gelated with pH-responsive polyanions with ROS-scavenging properties such as polyacrylic acid and hyaluronic acid. Then, pH- and ROS-responsive nanoparticles were used for selective transfection into reactive astrocytes and axonal regeneration in spinal cord injuries.... 

In this research the performance of the Moving Bed Biofilm Rector (MBBR) in different amounts of dissolved oxygen (DO) was investigated. Reactor with a useful volume of 15 liters was used in this study. In order to obtain optimum oxygen concentration, stayed at 6, 10 and 15 hours, and at different levels of dissolved oxygen in the range 0.5 -6 mg/lit, the amount of organic material was removed respectively. Also, in two different aeration intensity of 3.5 and 5.5 liters per minute at different values of e% (percentage of filling of media) the mass transfer coefficient values were obtained. When the aeration intensity increases from 3.5 to 5.5 liters per minute, and the percentage of 40%... 

Anzali wetland, in the Caspian Sea, northern Iranian province of Gilan, ranges from fresh near the tributary streams to brackish near the mouth into the harbor and the sea. Anzali wetland has faced with the serious levels of eutrophication because on the other hand, the lagoon has decreased in size during current century, to less than a quarter of its former extent and on the other hand, this wetland is faced with entering a huge amount of nutrient elements due to human activities in its watershed. Discharge of industrial wastewater, animal wastes, timber harvesting and the most important entering, rice farms irrigated wastewater are of the considerable causes of eutrophication in wetland....