Sharif Digital Repository

Polychlorinated Biphenyls are a class of organic compounds that are composed of two biphenyl rings attached by 1-10 chlorine atoms. Due to their specific properties, such as physical and chemical stability, flame resistance, and dielectric properties, these compounds are used as dielectric liquids, heat-exchange fluids, hydraulic liquids, plastifiers, and especially as Askarel oil in power plant transformer. Because of their high persistency in the environment, high toxicity, and bioaccumulation in the adipose tissue of humans and animals, their production is banned in most countries, and their use has been limited. There are different methods for detoxification of these compounds, and in... 

Intelligent transportation systems (ITS), refers to systems in which various types of data receiving and processing operations of traffic and transportation, as well as management and control, are used by automated and intelligent tools and by using modern electronic and control platforms along with the relevant planning. In intelligent transportation systems, new communication, electronic and optical technologies along with computer technologies, mechanical equipment, etc. are used for data retrieval and data mining that the required data is usually received and collected automatically and instantaneous, integrated and simultaneous access to the data set of the transportation network makes... 

Levofloxacin has been widely used in recent years as an antibiotic in the treatment of various bacterial infections. This drug compound is known as a newly emerging contaminant. In this study, the degradation of this pollutant has been investigated using advanced oxidation processes, biological process, and a combination of advanced oxidation-biological processes. In order to evaluate the degradation of levofloxacin with advanced oxidation processes, an electrochemical process was used. Advanced oxidation processes were carried out to optimize initial concentration parameters of the contaminant (5-15 milligrams per liter), electrolyte concentration (2.5-10 grams per liter), and current... 

Statistics show that plastic production in the world is increasing, with 335 million tonnes in 2016 reaching 367 million tonnes in 2020. Since the presence of plastics in the dimensions of micro and nano, especially in aquatic environments can have adverse effects on human health and other living organisms, it has raised major environmental concerns. Therefore, it is necessary to think of measures to remove them and develop efficient methods for eliminating and decomposing microplastics. Recently, the advanced oxidation processes have attracted much attention because of the ability to eliminate recalcitrant compounds. In this study, electrochemical techniques and Fenton-based techniques for... 

Land subsidence is a gradual settling or sudden sinking of the land surface from changes that take place underground. There are different causes of land subsidence; most notably, groundwater overdraft and severe weather conditions. Subsidence of the land surface due to ground water overdraft is caused by an increase in the intergranular pressure in unconsolidated aquifers, which results in a loss of buoyancy of solid particles in the zone dewatered by the falling water table and accordingly compaction of the aquifer. In this study, an experimental approach was developed to examine applicability of Microbially induced carbonate precipitation (MICP) for land subsidence control under... 

In recent years, the biodegradation of micro-contaminants using enzymes has attracted the attention of many researchers in the field of environment and health. Micro- and nano-scale environments play an important role in enzymatic catalysis that directly affects the activity and stability of enzymes. Therefore, setting a nanoscale environment for enzymes is very important, especially in liquids with undesirable properties (such as pH, temperature, toxicity, etc.) in this work, a method proposed in which the pH and the substrate concentration are regulated for enzymatic catalysis using a metal-organic framework, consisting of Glucose Oxidase (GOx) and Horseradish Peroxidase (HRP) immobilized... 

One of the major environmental problems in recent years is the presence of micropollutants that cause many problems for the environment and living organisms. Diclofenac is one of the micropollutants and endocrine disruptors. Conventional treatment methods do not have the ability to effectively remove pharmaceutical pollutants and micro-pollutants, and finding a suitable approach to remove these pollutants is of great importance. In recent years, biological methods such as the use of enzymes and molds have received attention, but due to the relative removal of pollutants, these methods have been combined with membrane technology to improve the level of pollutant removal and increase the... 

This thesis has developed a novel platform for digital dentistry which facilitates the interoperability among different digital components and improves digital workflow in a collaborative environment. The platform is inspired by the cloud manufacturing paradigm for enabling the interoperability and collaboration management and also applies the DICOM standard to improve the integration for the coordination among the different stakeholders for better sharing of their resources while they are geographically distributed. The paper has proposed the application of the PACS concept to include design, implant planning, process planning and production workstations. The paper has conducted a... 

Providing a precise estimation of the position of a moving element is one of the requirements of many position control systems. Resolvers, as electromagnetic sensors, are one of the most suitable options for use in harsh environments with high thermal and mechanical stresses and high contamination. Although resolvers are the most reliable solution for sensitive applications in stressful environments, they are less accurate in normal operating conditions than optical encoders. In this regard, many efforts have been made to reduce the estimated position. Most of the studies have focused on modifying the electronic converter structure, which is responsible for processing the output signals of... 

Microbially-induced calcium carbonate precipitation is a low-cost, environmentally friendly, novel ground improvement technique that has received much attention in recent years. Most studies on biological soil stabilization have investigated the mechanical and hydraulic behavior of soils in dry and saturated conditions. However, the behavior of soils stabilized by this method in the unsaturated state should be of immense concern through the extent of unsaturated soils in nature. Therefore, this study aims to investigate the effects of microbially-induced calcium carbonate precipitation on the soil-water retention curve and changes of small strain shear modulus of unsaturated cemented and... 

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... 

Contaminants in drinking water, including microbial contaminants, have a great impact on the health of people in the community and can seriously threaten public health. In recent years, diseases caused by pathogenic bacteria due to the consumption of contaminated water have led to many deaths. As a result, water treatment has been one of the most important human concerns. Among the new water treatment technologies, metal-organic(MOF) frameworks are a new generation of porous materials that have properties such as high surface area, water stability and functionality due to their dual structure. As a result, they are widely used today in various scientific fields, including water purification.... 

This thesis is divided into three parts: In part I, interactions of neutral and anionic forms of histidine with coinage metal nano clusters M3 (M = Au, Ag and Cu) are investigated. Results demonstrate that nonconventional M…H-O hydrogen bonds and M-X bonds (X = N, O) play stabilization roles in interactions of histidine and metal nano clusters. Presence of negative charge in ligand leads to increase of binding energy of complexes. In the next step, the effects of coinage metal nano clusters on the gas-phase acidity of weak organic acid (histidine) have been explored. The acidity of isolated histidine is compared with the acidity of its Au3–, Ag3– and Cu3–complexed species. Moreover, pKa... 

In recent years, non-biodegradable microplastics (MPs), which cause a lot of pollution in the environment, have become a major concern worldwide. Due to their small size and large surface area, these plastic particles have a great ability to be absorbed into biological cells. Due to their hydrophobic surface, these particles have the ability to absorb pollutants such as heavy metals, toxic medicinal substances, softeners, etc. Microplastics are usually persistent in the environment, allowing them to be transported along the food chain. Research on the degradation of microplastics is focused on biological and non-biological approaches. To date, microorganisms such as algae, fungi, and... 

A system of electrospun scaffold containing drug-loaded chitosan nanoparticles was introduced for using in spinal cord tissue engineering. In spinal cord injury treatment, the formation of glial scar after injury which contains proteoglycans and activate glial cells should be avoided. In this study, the release of Dexamethasone sodium phosphate (DEXP) as a steroid anti-inflammatory agent from electrospun nanofiber composite containing chitosan nanoparticles was investigated. DEXP is believed to act through its glucocorticoid receptors found in most neurons and glial cells. These receptors’ pathways are involved in the inhibition of astrocyte proliferation and microglial activation.... 

Recently Infrared imaging has been very much considered for its applications.and because the infrared wavelengths are harmless, considered in medical and industrial applications. the imaging system examined in this thesis is passive and the object's own radiation is received by a single-pixel detector, these images are taken by two superconducting sensors and a pyroelectric Sensor. the purpose of this thesis is to improve the quality of images And reconstruction for the resulting images and if possible, optimize the system. to improve this system, various work has been proposed and done. including parabolic mirror distortion survey available in the system and compensated for it, take a... 

This thesis is divided into three parts: In part I, conformational properties of neutral, anionic, cationic and zwitterionic forms of glutathione tripeptide were investigated by means of DFT-B3LYP method with 6-31+G (d,p) basis set. Results show that glutathione is a very flexible molecule and its conformational energy landscape is strongly influenced by forming intramolecular hydrogen bond and its charge. Conformation of each amino acid in glutathione tripeptide depends on its orientation within the peptide sequence in addition to the conformation of other amino acids within the chain. Investigation of intramolecular hydrogen bonds in these conformers by means of AIM analysis demonstrates... 

Acidizing is the most widely performed job to remove the formation damage, and enhance the oil recovery. Different models have been introduced to design the optimized condition for acidizing. However, none of them are able to predict the optimum injection flow rate in the actual application. As a result, Calcite cores are extracted from reservoirs for conducting experiments and modifying the present models. Nevertheless, acidizing is an intrusive technique destroying the costly extracted cores. Thus, there is a need to construct calcite cores of various porosities and permeabilities to take advantage of them in acidizing modelling.Microbially induced calcite precipitation is a well-known... 

To develop a novel cell culture method for enhancement of bone marrow stromal cell growth and infiltration into the 3d electrospun PCL-based scaffold, we utilized the RPM system to simulate microgravity. In current study, six different scaffolds are produced using the electrospinningelectrospraying technique. These scaffolds are compared based on their structural (average diameter and SEM micrographs), mechanical (Tensile strength, elongation and wettability) and biological (Biodegradability, bioactivity, biocompatibility, cell adhesion, cell infiltration and antibacterial quality) characteristics. It is noted that the porous nano-hydroxyapatite/titanium hydroxide/polycaprolactone...