Sharif Digital Repository

QSAR studies play an important role in drug design and lead optimization by developing a mathematical relationship between the chemical structures of compounds and their biological activities.By using such an approach one could predict the activities of newly designed compounds before a decision is made whether these compounds should be really synthesized or tested. The main aim of the present work was to develop a QSAR model for predicting the inhibitory activity of acetyl CoA carboxylase (ACC)derivatives as anti-diabetic inhibitors. Since variable selection is a critical step in every QSAR study, four different algorithms, based on Monte Carlo cross-validation techniques, were... 

Electrocatalytic oxidation of L-ascorbic acid (L-AA) on silver electrode in alkaline solutions was studied employing cyclic voltammetry, chronoamperometry and impedance spectroscopy techniques. In comparison to Pt, the onset potential for L-AA electro-oxidation process on Ag, in a solution containg 0.02 M L-AA and 0.5 M NaOH, was 0.1 V more negative. Also, L-AA oxidation current increased more than 900% at -0.26 V/SCE. According to voltammety and impedance spectropy findings, although hydroxide anion presence was vital for L-AA oxidation to occur, at potentials more positive than -0.2 V/SCE, hydroxide ion tends to inhibit the oxidation process. Studies on the L-AA oxidation process on Ag in... 

Schiff bases are used as prevalent ligands in coordination chemistry and are prepared easily. Their application as mild inhibitory agents for prevention of various steel’s corrosion in acidic solution has been proved. When their structure is altered, multi-purpose application for them is found. This property has led to a motive for research and study. In this study, electronic properties of a group of Schiff bases are investigated. The goal of this study is using quantum mechanics (QM) as a tool for specifying electronic properties of some of these bases. With respect to QM calculation which is done by density functional theory (DFT), their properties as inhibitory agents are studied. First,... 

Nowdays, it has been shown that protein misfolding is involved in more than forty diseases including Alzheimer’s and Parkinson’s. Alzheimer’s disease is one of the most common neurodegenerative diseases that disrupts brain function. The main cause of this illness is due to formation of extracellular amyloid plaque from a 42-amino acid-peptide called amyloid beta. Amyloidosis is caused by missfolding of peptides and proteins mainly because of physical and chemical changes in biomolecule or their environment.
Therefore, in this dissertation, using synthetic and recombinant abeta peptide, kinetic of amyloidosis was examined. Ultrasmall peptides (three-amino acid), containing branched chain... 

Alzheimer’s disease (AD) is the most common type of dementia in the elderly. The neuropathology and treatment of AD is not precisely determined yet, but according to the pathological studies, AD is associated with presence of toxic soluble oligomers and insoluble senile plaques formed by amyloidosis of Amyloid Beta (Aβ) in neocortical region of brain. An attractive therapeutic approach to treat AD is to identify small ligands that are capable of binding to critical residues in order to inhibit or reverse Aβ amyloidosis process as source of neurotoxicity. In this area, therapeutic efforts designed various organic agents and most of them focused on the N-terminal sequence of Aβ. The aim of... 

In this study, pitting corrosion of 304, 316 and 316L stainless steels in 3.5% NaCl solution at different temperatures (25, 40, and 70°C), were studied by electrochemical methods such as Cyclic Potentiodynamic Polarization, Electrochemical Impedance Spectroscopy and Immersion tests. Also, the effects of different concentrations of polyethyleneimine with two molecular weights (2000 and 60000 g/mol) on pitting corrosion of these steels were investigated. Finally, the adsorption behavior of inhibitors on surface of alloys was investigated by Atomic Force Microscopy (AFM) and Attenuated Total Reflectance Fourier transform spectroscopy (ATR-FTIR). It was found that both inhibitors prevent... 

Bioorthogonal chemistry defines any reaction, inside or outside the living systems, without interfering with native chemical processes and 3dimensional structure of proteins. In these types of reactions water is the sole solvent; a neutral pH is required; the temperature must be up to 40 oC. The kinetics of reactions must be on the hour scale and the nontoxic reagents with low concentration must be used. One of the simplest methods of visualizing protein molecule is covalent attachment of fluorescein to protein. In this work several fluorescent compounds were synthesized. These novel compounds include acylchloride fluorescein, N-hydroxysuccinimide fluorescein, thiophenol fluorescein, and... 

According to the importance of conversion and transmission of energy, and introduction of hydrate formation process as an alternative method, in this study, the nano-graphene oxide is used to increase the rate if methane gas hydrates formation. The experiments were performed at different concentrations of 30 to 70 ppm and the results were compared with pure water. The effect of temperature and pressure on hydrate formation at temperatures of 1 and 2˚C and pressures of 48 and 53 bar were studied. And it was found that nano-graphene oxide can be used to accelerate the methane hydrates formation. The effect of ultrasonic on methane hydrate formation has been studied that it was found that the... 

In recent years, nanodiamond (ND) has been used as reinforcement in polymeric nanocomposites in order to improve mechanical properties, thermal conductivity, etc. The surface of nanodiamond has several functional groups which make it appropriate adsorbent. In this study, nanodiamond was modified with dodecylamine corrosion inhibitor and was utilized (1wt %) in epoxy based nanocomposite. Fourier transform infrared spectroscopy (FTIR) analysis was used to confirm the surface modification of Nanodiamond. In order to estimate the loading amount of corrosion inhibitor, thermogravimetric analysis was investigated. FE-SEM analysis demonstrated nanoparticle dispersibility in epoxy matrix. Regarding... 

In this study, the effects of different corrosion inhibitors on the corrosion of aluminum alloy which is used in the cooling systems of automotive industries were investigated. Also a comparison between the corrosion behaviour of the mentioned aluminum alloy with and without any galvanic connection to 5 different metals consist of solder, stainless steel, mild steel, brass and copper was done. The corrosion rate became more by establishing galvanic coupling. The base solution was ethylene glycol and water which is the base part of all antifreeze compounds. The tests were done at high temperature about 88ºC. Two different industrial corrosion inhibitors were examined in these conditions.... 

Today, the process of corrosion and compensation of minor injuries, without the need for tracing or any other physical interference, has become one of the subjects of interest to researchers. Inhibitors have been considered as one of the anti-corrosion agents. In this research, safflower extract as a green inhibitor in sodium chloride corrosive environment was used to evaluate the rate of corrosion of mild steel. Also the MoS2 nanoparticles were used as carrier of this green inhibitore in the epoxy coating to allow the activation of the coating in a scratched state in sodium chloride solution of 3.5%. In the first step, the extract of the safflower was prepared to reach the best part of this... 

Inappropriate performance of the air-cooled condensers in the process industry will make the flow out of the air cooler not fully condensate and its pressure is greater than the design value. This will lead to product loss and safety issues. In this study, factors affecting the performance of air cooler and various solutions to solve these problems have been identified. As a case study, the first distillation tower of the Ali Siana Petrochemical Complex, which disrupts its function in some months of the year, has been investigated. Aspen Hysys process simulation software simulates the naphtha splitter unit and the Aspen Exchangers Design & Rating software simulates the air cooled condesor... 

Scale deposition is one of the reasons of formation damage during water injection process. This phenomenon often ocuures when two incompatible waters that interact chemically and precipitate minerals, mix within the reservoir. A typical example is sea water, with high concentration of sulfate ion and formation water, with high concentrations of calcium and/or barium ions. Mixing of these waters, therefore, can cause precipitation of calcium sulfate and/or barium sulfate. This study was conducted to investigate the permeability reduction caused by deposition of calcium and barium sulfates in carbonate cores from mixing of injected sea water and formation water in two flow rates and two... 

Matrix acidizing treatment are performed to enhance the permeability of oil and gas formations by removing pore plug. Numerous additives have been introduced to aid the penetration of the acid or to perform other important tasks. To be able to pump the reactive fluid from the surface through the tubing and into the formation, corrosion inhibitors usually is necessary to protect the metal from attack by the fluid itself. In this work the Henna extract introduced as a pre flush additive and corrosion inhibitor in acidizing operation. It also enters the formation and effect on the matrix permeability and acidizing performance. The effect of Henna extract on permeability of rock will be... 

In this study thermodynamics and kinetics effects of two ionic liquids (ILs) on the formation and dissociation of methane and carbon dioxide hydrates were investigated. The ILs used in this study are 1-butyle-3-metylimidazolium tetrafluoroborate, [Bmim][BF4], and 1-butyle-3-metylimidazolium methyl sulfate, [Bmim][MS]. At the first step of experimental section, the tetrahydrofuran (THF) was used in atmospheric pressure. The structure of THF hydrate is similar to natural gas hydrate; therefore it is used as a model for studying the properties and investigation of inhibitors effects on gas hydrates. In order to consider the effects of foregoing ILs on the formation and dissociation of gas... 

Prevalence of Multiple Drug Resistant Tuberculosis and use of Yersinia-Pestis in bioterrorism warrants synthesis of new antimicrobial agents. Although Pyrazoline derivatives were first synthesized as antimicrobial drugs, but they also had Mono Amine Oxidase inhibitory effects. In this Quantitative Structure – Activity Relationship (QSAR) study, MAO-I activity of pyrazoline derivatives were evaluated. By applying semi-empirical quantum calculations at AM1 level, optimum 3D geometry of 32 molecules were obtained.After descriptor generation, Principal Component Analysis (PCA) was performed to fiind out 5 outliers. After omitting outliers and sorting molecules according to IC50 values, Stepwise... 

Butadiene is one of the most widely used materials in the Iran polymer industry. In order to use this material in the first step, the inhibitor must be separated. Consequently, at the start of the project, the separation of Tert butylcatechol inhibitors from butadiene was studied by the adsorption process on active alumina. The results of the condensed butadiene gas chromatography–mass spectrometry test indicate that, by using the active alumina as an adsorbent, the tert butylcatechol will be removed completely. In the next step, 1,3 butadiene, acrylonitrile, acrylic acid acid terpolymer, which one of its applications is manufacturing of artificial teeth, was synthesized by emulsion... 

Asphaltene precipitation and deposition are sources of a number of problems for petroleum industry. Thus, solving the problem of precipitation and deposition is very important. In order to measure deposition level, study of other asphaltene flocculation is vital; since there is a time interval between precipitation and deposition. Use of chemical inhibitors is one of the best methods for prevention of asphaltene precipitation that could postpone precipitation point and prevent formation of huge flocculations. In this study, effects of asphaltene flocculation size on deposition with or without using inhibitors were investigated. In this regard, QCM was used for measuring the amount of... 

At the molecular level, proteins control almost all the biochemical reactions in the cells. In order for proteins to function, they must be able to fold into their unique 3D structure. Deformation of protein structure due to some environmental phenomena such as pH, high temperature, and stress may cause unfolding of proteins and finally result in formation of protein fibrils called "amyloid". Amyloid has been found in a number of human diseases such as Alzheimer, type II diabetes, and Parkinson. Recently pyridazine has been under spotlight due to its unique chemical properties such as high dipole moment and higher solubility in biological solvents. In this study, we aim at using a... 

The corrosion rate of steel (EN 10130 DC-04) in the presence of oleuropein in aqueous corrosive solutions (of different concentrations in 1M and 0.5M hydrochloric acid and also 3.5% sodium chloride) evaluated and results was shown that oleuropein can protect steel surfaces and it acts as good inhibitor. This means that the observations of linear polarization and weight loss experiments showed inhibitor efficiency more than 97% in acidic corrosive medium and above 74% for aqueous solution of 3.5% sodium chloride. Adding oleuropein at different concentrations (i.e. 300 ppm, 700 ppm, and 1000 ppm) to three different types of polymeric paint structures (nitrocellulose alkyd base, acrylic base,...