Sharif Digital Repository

In the first part of this work, citric acid monomer was selected to produce dendrimer through the divergent method using logical conditions (for controlling its functional groups) on the base of poly (ethylene glycol) as the core. Triblock copolymers (ABA-type) of citric acid and poly (ethylene glycol) (PCA-PEG-PCA) as biocompatible compounds were synthesized in four different molecular weights and applied as nanocarriers. The structure definition of the molecules and nanoparticles were carried out using different spectroscopy methods. Diameter of the synthesized copolymers was investigated using dynamic light scattering (DLS) experiments and transmission electron microscopy (TEM) and it was... 

Acidity values of some compound (e.g., alkanes, alcohols, carboxylic acids and amines) with or without boron substitute have been studied theoretically to evaluate the influence of boron on acidity of organic functional groups. We have derived the unoccupied reactive orbital that show the maximum localization on the boron pπ atomic orbital overlapping with the lone-pair orbital of an electron donor. Localization of unoccupied reactive orbital on the boron pπ atomic and the polarizability of the boron center are two factors which affect acidity values of functional groups. Conformational searching was performed using MM (Molecular Mechanics). The most important conformations were optimized at... 

In this study, a newly designed needle trap device (NTE) containing modified nanosilica as sorbent is used for sampling and preconcentration of some polycyclic aromatic hydrocarbons (PAHs) from headspace of aqueous solutions. An inexpensive modifier, cis-9-octadecenoic acid (oleic acid), which contains a long chain, was used to modify the surface of the nano-scaled silica particles. The hydrophobic interaction between oleic acid and aromatic compounds was the preliminary evidence for extraction of these compounds. After adsorption of selected compounds, thermal desorption was, subsequently, employed to transfer the extracted analytes into a GC–FID. Extraction time and temperature, flow rate... 

This thesis focouses on the preparation and super-swelling behavior of two superabsorbent hydrogel. In the first section, a new superabsorbent hydrogel based on agar was prepared and the effect of the ratio of some components(AA, AAM, MBA, APS and agar) on the swelling capasity of the hydrogel was studied. Maximum water absorbency of the optimized final product was found to be 614.5 g/g in distilled water. The structure of the hydrogel was characterized by FT-IR method and morphology of the samples was examined by scanning electron microscopy(SEM). Swelling behavior properties of optimized hydrogel sample in different swelling medium were investigated. In the second section, we report the... 

Application of nanoparticles in targeted delivery and controlled drug release is recently highly attracted especially in cancer therapy. In this study with the aim of developing a novel drug vector based on metallic nanoparticles, gold nanoparticles with their unique characteristics were used to design a vector for targeted anti-cancer drug delivery to tumor. First, gold nanoparticles were chemically synthesized therough sodium citrate and sodium brohydrate reductions with average diameters of 22 and 11 nm, respectively. Then, the activated poly ethylene glycol (PEG) and activated folic acid were conjugated to the lysine-capped gold nanoparticles. Subsequently, the widely used anticancer... 

We have reported a new and efficient synthesis of a broad spectrum of heterotetracyclic benzoxazocines via unique tandem 1,3-dinucleophilic addition of different bifunctional nucleophiles to quinolinium and isoquinolinium salts. The reaction generally involves the initial addition of nucleophiles to quinolinium salts to form enamine intermediate which can be trapped by intramolecular O/S-alkylation of nucleophiles. This protocol is a very mild and simple method for construction of eight-membered ring in fused heterocycles in a one-step process. We have also developed an efficient asymmetric synthesis of α,β-disubstituted γ-bisalkoxycarbonyl and α, β- disubstituted γ- phosphono sulfonates via... 

This thesis focuses on the preparation and super-swelling behavior of a superabsorbent hydrogel based on natural macro-molecules and loading potassium nitrite as an agro-chemical onto it. 1-In this investigation a new type of superabsorbent hydrogel based on Gelatin and k-Carrageenan was prepared and the effect of the feed ratio of some components (acrylic acid, MBA, APS, and agar) on the swelling capacity of the hydrogel was systematically studied. The structure of the hydrogel optimized final product was found to be 1064 g/g in distilled water. The structure of the hydrogel was characterized by FT_IR method and morphology of the samples was examined by scamming electron microscopy (SEM).... 

Briefly in this thesis, these subjects have been investigated: In recent years, water is used as a solvent instead of an organic solvents have become more and more important due to cheap and environmental consideration. In this context, preparation of quinoxaline, pyrrole, new 1,4-dihydropyridine and reduction of imine to amine with 1,4-dihydropyridine derivatives as the reducing agents with the use of one-pot multicomponent reaction have been reported. The existence of several hydrogen bonding groups (NH) in the new dihydropyridines they acts as biologically active compounds in the forthcoming years. In continuation, oxidation of thiols to disulfides in the presence of NBS and NCS and... 

In recent decade energy crisis causes research on luminescent devises gains special importance. Particularly, hybrid LEDs (organic- nanocrystal) have been studied by a number of researches due to their advantages. Easy fabrication and narrow spectrum of radiation are mentioned as the most important benefits. The emissive layer is the most important part in these diodes which made of semiconductor nanoparticles. There are a variety of chemical methods for synthesis of semiconductor nanoparticles. We focus on aqueous method for nanoparticles synthesis because of its advantages. Alloyed semiconductor nanoparticles of ZnxCd1-xS were selected for this research work. The manifest features of the... 

Poly (vinyl alcohol) (PVA) hydrogel is a biocompatible material, which has been widely applied in drug delivery applications. Microspheres, nanospheres, and other types of particle-based drug delivery vehicles have proven capacity for long-term release. There is growing interest to overcoming the inherent pharmacological limitations of hydrogels by formulating particulate systems into the hydrogel matrix to form new delivery platforms. We here describe a simple composite system based on poly (vinyl alcohol) (PVA) hydrogels containing entrapped drug-loaded poly (lactic acid) (PLA) microspheres for controlled delivery over extended period of time. Gamma-Irradiation and freeze-thawing was... 

Part 1: A novel modified pyrolytic graphite electrode with nanodiamond/graphite was fabricated. The electrochemical response characteristics of the modified electrode toward the epinephrine (EN) and uric acid (UA) are studied by means of cyclic and linear sweep voltammetry. The structural morphology and thickness of the film was characterized by SEM technique.The prepared electrode shows an excellent catalytic activity in the electrochemical oxidation of EN and UA, leading to remarkable enhancements in the corresponding peak currents and lowering the peak potentials. The prepared modified electrode acts as a highly sensitive sensor for simultaneous determination of EN and UA in the presence... 

Hydrogen bond is a type of molecular bonds which occurs between hydrogen and a highly electronegative atom( usually F, N and O) and results to special properties. Polyols and multihydroxyl compounds are among substances which have special properties such as acidity due to the existence of hydrogen bond in their molecular structure. Acidity in these compounds is a result of having stable anions due to intramolecular hydrogen bands. The existence of an electronegative group in addition to hydroxyl groups leads to increase the acidity in these substances. In this project acidities of some polyols and multihydroxyl compounds were calculated in both gas phase and solution phase( DMSO,... 

Selective oxidation of H2S to elemental sulfur in a fixed bed reactor over seven nanocatalysts has been investigated and compared to commercial claus catalyst. Among them, Al2O3-supported sodium oxide nanocatalyst prepared with wet chemical technique and Al2O3 nanocatalyst prepared with spray pyrolysis method were the most active catalysts for selective oxidation of H2S to elemental sulfur. The remaining nanocatalysts were deactivated, mainly due to the interaction with H2S and conversion into sulfides. For synthesis of Al2O3 with spray pyrolysis method we use statistical design of experiments (box-behnken design) in order to screen the effects of significant synthesizing parameters  

Nanosized CdS coupled TiO2 nanocrystals were prepared by a microemulsion-mediated Hydrothermal method at relatively low temperatures. Modification of this nanocomposite with Tyrosine,Phenylalanine,Glysine and Glutamate ,especially Tyrosine resulted in enhanced photocatalytic degradation rate of Nitrobenzene( NB ) compared to using CdS-TiO2 under visible light irradiation. The prepared samples were characterized by BET,SEM, XRD, UV–Vis spectroscopy ,FTIR .It was found which have high surface area about 470 m2 g−1 and mesoporous character with the average pore diameter of 2.8 nm.The results showed this nanocomposite consisted of uniform anatase TiO2 with highly dispersed cubic phase CdS... 

To obtain solutions containing Titanium, leaching of Ilmenite Concentrate of Kahnooj and its Slag by Sulfuric Acid 98% in various Conditions are Studied. Screening tests by Fractional Factorial method were designed, at this step effects of Temperature, Acid Concentration, Particle Size, Solid to liquid Ratio, Time and Stirring Speed were investigated and It was Concluded that Temperature, Time, Acid Concentration and Particle Size were the effective Parameters in both leaching process of Ilmenite and Slag. The Temperature, Time and Acid concentration had positive effect, whereas the Particle Size had negative effect. After screening step, effective parameters were optimized by Rotatable... 

Ternary copper (II) complexes having heterocyclic bases and α-amino acid salicylaldiminates
as models for the type-2 sites in copper oxidases are of great biological importance. Considerable attention has given to mixed ligand complexes due to their antitumore, antimicrobial , inflammatpry , ascorbate oxidase (AO) and dopamine β-hydroxylase(DβH) and radio- imaging properties. With this in mind, new copper (II) complexes including amino acid Schiff base and heterocyclic bases (1,10 phenanthroline and 2, 2 biprydine ) have been synthesized, investigated and characterized by IR, UV-Vis and CHN. In the case of amino acid Schiff-base complexes, the tridentate ONO Schiff base ligand... 

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... 

Mesoporous silica nanoparticles (MSNP) have attracted lots of attentions because of their particular characteristics. Physical characteristics such as structure, morphology, porosity, and size of these nanoparticles have strong impact on their function and it can be conceived a wide range of applications for them by manipulating these characteristics. In this research, monodispersed MSNPs with a controllable size in the range of 50-130 nm and pore size in the range of 4-24 nm were synthesized and positively functionalized in order to develop a carrier for the delivery of nucleic acids (siRNA and pDNA). The MSNPs were synthesized by the template removing method.In this method, sodium... 

In this research, using a hydrochemical model alongside three dominant instabilities of shape, Bjerknes and diffusion, the effect of ambient parameters on the single bubble sonoluminescence (SBSL) in Sulfuric Acid (SA) is studied. The phase diagrams of the bubble in the (R0 − Pa) space are presented, and the parametric dependence of the light intensity is discussed. In a part of this research a hot plasma core is considered at the center of the bubble. The study of ambient temperature shows that in contrast to water, the calculated thermalbremsstrahlung mechanism of light emission at the fixed degassing condition of high SA concentrations shows that with increasing the temperature of aqueous... 

An optimization condition for obtaining Ni-Zn-P electroless alloy coating has been developed. The sulphate bath with sodium hypophosphate as a reducer and sodium citrate and ammonium chloride as complexing agents were used. The effect of variation in the pH level , temperature , time of deposition and reactants concentration on stability of bath, coating composition, microstructure, microhardness and corrosion resistance of coatings was investigated. The composition of coatings was obtained by using the EDAX analysis. To investigate coating morphology, SEM images were taken and to study the corrosion behavior of coatings potentidynamic polarization, Electrochemical Impedance Spectroscopy...