Sharif Digital Repository

Drying is one of the important downstream processes in the production of biotechnological products. The dryer design for heat-sensitive materials such as proteins requires special process considerations. In this study, a rotary dryer evaluated for drying protein products. The used liquid enzyme as model, a bacterial α-amylase, first, immobilized on sodium sulfate and sodium tripolyphosphate as carriers in a spraying mode and then, the obtained wet solid materials containing the enzyme, dried in a batch dryer. The performance of this dryer investigated to achieve suitable properties such as the enzyme activity and the final moisture content of product by changing the process conditions.... 

In the world today, biological materials widely used are which requires proper packaging, the types of enzymes are used in various industries: food, pharmaceutical, cosmetics. Shelf Life of enzymes Limited and affected by internal and external factors a maximum of one year. Internal factors include water activity, pH, microbial flora, oxidation-reduction potential, chemistry and biochemistry products, product formulation, additives and the reaction with package. External factors such as relative humidity, light, gas atmosphere within the package, the storage conditions and temperature. Water activity and relative humidity are important factors in spoilage. Avoid drying, lipid reaction,... 

In biotechnology processes, in addition of culture media there is a solid phase which dispensed across the system.In most of bioprocesses, first operational unit for downstream treatment is the separation of this particles from fermentation liquor. In contrast with other categories like inorganic chemistry, solid particles in fermentation liquor (which the main part of it is biomass itself) have complicated physical & rheological properties. For example, all of biomass species are hydrophilic and sometimes form colloidal solutions.With this perspective, separation of solid phase from fermentation liquor is a hard challenge in this kind of processes.In this research, with regard of great... 

The outbreak of a type of corona virus in 2019, plunged the world into a huge panic. Businesses entered into an unprecedented recession and economic growth was severely reduced. Millions of people have been infected and unfortunately countless numbers have also lost their lives. This which quickly crossed the borders of countries, proved how much a not-so-deadly infectious disease can affect human life. Another point that was revealed was the importance of epidemiology knowledge. Since the beginning of the outbreak of this disease, scientists in this field have tried to predict the state of the disease in the coming days by presenting models. Many countries formed special working groups to... 

Determining the best location for new wells is a complex problem that depends on reservoir and fluid properties, well and surface equipment specifications, and economic criteria. Various approaches have been proposed for this problem. Among those, direct optimization using the simulator as the evaluation function, although accurate, is in most cases infeasible due to the number of simulations required. This study proposes a hybrid optimization technique (HGA) based on the genetic algorithm (GA) with helper functions based on the polytope algorithm and the neural network. Hybridization of the GA with these helper methods introduces hill-climbing into the stochastic search and also makes use... 

Evidently, environment contamination by water insoluble chemicals present at the industrial wastes could bring about catastrophic consequences to the biosphere. Biological based cleaning technologies are commonly considered as a practical remedy to remove these contaminations. In fact, these techniques are founded on the ability of certain microorganisms to degrade the contaminants. It is crystal clear that the availability of contaminants to the microorganisms is an essential parameter determining the final efficiency of the biodegradation process. In practice, the limited solubility of the contaminants in the aqueous phase leads to mass transfer constraints which consequently, decrease the... 

In this research, an amperometric inhibition biosensor for the detection of cyanide has been fabricated by immobilization of the horseradish peroxidase (HRP) on the surface of glassy carbone electrode (GCE). Chitosan/acrylamide was applied for immobilization of HRP on the working electrode. All electrochemical measurement were carried out with three electrode: Ag/AgCl electrode as reference electrode, GCE as working electrode and platinium electrode as counter electrode which immersed in phosphate buffer solution. The amperometric measurement was done at an applied potential of -100 mV versus Ag/AgCl with a scan rate of 100 mV in the presence of hydroquinone as electron mediator and... 

The main objective of this project is the deposition of photo-catalysts on cement and concrete blocks with an emphasis on commercialization. We started with an extensive study of common methods introduced in previous literature, and conclude with a number of suggestions for industrialization. First, slurry and sol-gel deposition of the photo-catalysts on blocks of type 2 commercial cement which is one of the most used materials in construction of buildings and waste-water treatment plants has been examined to reach a method of sample formation. Due to the simplicity of common methods and low quality of formed samples (less than 5 percent aging efficiency), the obtained experience was used to... 

Presence of heavy metals in industrial waste has always been a serious environmental problem. One of such metals in uranium that is used in important industries such as nuclear industry. Thus, it must be excluded from industrial waste efficiently. This research aimed to study effect of local strain of aspergillus niger in bioabsoprtion of uranium from industrial waste in which good absorption was reached and absorption of local strain was compared with that of control strain obtained from PTCC. Also, local strain was collected from uranium anomalies of Bandar Abbas Mining Site and was used to identify it with reference strains available at NCBI site using PCR and proliferation of part of... 

In this research, the behavior of surfactin at the presence of water, decane, and asphaltene is investigated. Decane is chosen instead of crude oil to simplify the model. In the first chapter, basic molecular structures are introduced. Furthermore, in the second chapter molecular dynamics simulation, as the main tool in these simulations, is introduced. In the third chapter, one of the most important quantities in chemical engineering, diffusion coefficient, is chosen to investigate the efficiency and accuracy of molecular dynamics simulation method to calculate such a quantity and results show that molecular dynamics simulation can present accurate quantities, more accurate than common... 

This project related to gas purification according to difference in the deposition point in the fludized bed.The main reason for choosing fluidized bed is increasing overall heat transfer coefficient compare in to other heat exchangers. Separation process, by cooling the wall causes the self- deposition gas phase shifts to solid phase. Solid formed on the wall, act as an insulating layer and greatly reduces the heat transfer. To solve this problem, the fluidized bed system is offered because fluid particles in addition to remove the insulating layer, improving convection heat transfer coefficient . Laboratory tests show the feasibility of preventing the formation of insulating layer by... 

Many aroma compounds of fruit juice recovered by thermal evaporation and distillation processes can lead to undesirable chemical changes and even their loss. Pervaporation is a promising process for the recovery of volatile organic compounds from their aqueous solutions. In the present work, pervaporation recovery of Ethyl acetate as a model solution of apple juice’s aroma compound was evaluated with polyvinylidene fluoride (PVDF) and ethylvinylacetate (EVA) membranes. For PVDF and PES membranes in the feed concentration of 250-1000 ppm and the operating temperature of 30 ºC, separating factor , respectively, was obtained in the range of 67-70 and 49-53, and also total permeation flux was... 

Microbial electrolysis cell- microbial fuel cell (MFC-MEC) coupled system is one of the novel method, for in-situ utilization from the wastewater and generating electricity and hydrogen simultaneously. In this system, required energy for microbial electrolysis cell supply by electric energy generated in microbial fuel cell. Implementation of this system is complicated, because of its unsteady state nature. In this study, it is demonstrated that the hydrogen production in such an MEC-MFC coupled sustem can be manipulated through adjusting the power input on the MEC. The power input of the MEC is regulated by adding MFCs connected into the circuit in series. When one MFC add to the coupled... 

Recently separation technology has been developed and engineers are trying to find more rapid and more economic ways in order to reach pure materials. One of the most important needs of human being is natural gas which has some impurities. Acid gases such as carbon dioxide and hydrogen sulfide must be separated from methane. This operation is called gas sweetening. Membrane contactors are equipments recently developed and may be used instead of packed towers for gas sweetening in the future. In this project we designed and made a membrane contacting unit to separate carbon dioxide and hydrogen sulfide from methane. This unit lets you to study the effect of many parameters such as gas and... 

In this work, bioleaching was used to extract valuable uranium from a low grade ore. Bioleaching experiments were carried out in batch cultures using a native strain of Acidithiobacillus ferrooxidans. Experiments were conducted to investigate the effects of rotation speed, initial redox potential, initially added Fe concentration, particle size, pH, temperature, pulp density, and culture type. In the shake flask systems, over 99% of the uranium was bioleached in 48 hours at some conditions. Uninoculated flasks gave only around 25% leaching. At each study, uranium and iron concentrations, solution oxidation– reduction potential and pH were measured. The results showed that 150 rpm, d80=100 ... 

In this study three type of nanofiltration membranes were prepared from PVC for water softening; (i) asymmetric PVC nanofiltration membrane, and two different thin film composite (TFC) membranes: (ii) polyamide (PA)/PVC composite membrane (iii) poly vinyl alcohol (PVA)/PVC composite membrane. Asymmetric nanofiltration membranes were prepared by phase inversion. The effect of PVC concentration, solvent (THF) and additive (PVP) on morphology and performance were studied by scanning electron microscopy (SEM) and measuring pure water flux and salt rejection. Increasing PVC concentration decreased pure water flux and increased salt rejection. Adding tetrahydrofuran(THF) decreased the pure water... 

Complex directed networks are widely used in representing, modeling and summarizing various homo and heterogeneous real networks such as protein-protein interactions, social and twitting networks, brain connectomes, chipsets mapping and marketing. While working on undirected networks in the hope for detecting communities or any other static and dynamic structures, has been on agenda of many physician and computer scientists, dealing with directed ones seems more challengeable for quick advances. Availability of theoretical basis especially symmetric adjacency matrix recommends modeling with undirected graphs but we believe that directed graphs are more general and practical to model real... 

Labneh is a semisolid product that is produced by concentrating milk to approximately 23% total solids (wt/vol) by the traditional cloth bag method, ultrafiltration and direct reconstitution. For ultrafiltration membrane processing is carried out either before or immediately after fermentation. The effect of storage time on the flow properties of concentrated yogurt (labneh) was investigated using a rotational viscometer. Experiments were performed at after 0, 2, 5 and 14 days after production. The apparent viscosity of fresh sample was then measured as a function of shear rate. For a given shear rate, the apparent viscosity was measured as a function of shearing time. The increase in the... 

Today, almost all the country's needs in the field of industrial enzymes are met through imports. In this regard, much attention has been paid to the industrial production of various enzymes in the country. The production of recombinant proteins through strain engineering is one of the most important ways to meet this demand due to its many benefits. One of the most important microorganisms that is widely used in the enzyme industry is Bacillus subtilis. Due to its thick peptidoglycan wall, this gram-positive bacterium hardly accepts engineered carriers for genetic modification as hosts. The aim of this study was to evaluate the permeability of the wall and cell membrane of Bacillus subtilis... 

With the increasing emphasis on production of various chemicals by biotechnology industry, the establishment of optimal cell factories for the maximum production of a specific chemical product will be a serious challenge in large-scale production in this industry. Metabolic engineering is a branch of biochemical engineering that has been developed to achieve this and the approaches in it seek to address this challenge. In this study, focusing on increasing production of fatty acids by yeast cells of Saccharomyces cerevisiae, and using a combination of computational and laboratory methods to present a methodology for the optimal design of culture media. Thus, using the constraint-based...