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Studies on glutaraldehyde crosslinked chitosan hydrogel properties for drug delivery systems
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 62, Issue 11 , 2013 , Pages 605-611 ; 00914037 (ISSN) ; Ramazani, S. A. A ; Shafiee, M ; Danaei, M ; Sharif University of Technology
2013
Abstract
Chitosan was crosslinked with different amount of glutaraldehyde to prepare appropriate hydrogels to be used as drug delivery system. The swelling behavior of freeze-dried hydrogels in aqueous media at different temperature and pHs has been examined. The swelling, porosity and biocompatibility behavior of samples were investigated to check effects of polymer/polymer and polymer/drug interactions on these system characteristics. Obtained experimental results illustrates that with increasing crosslinking agent from 0.068 to 0.30, swelling of the prepared samples degrees from 1200% to 600% and pore diameters change from 100 to 500 μm. To investigate systems biocompatibility in gastric...
Exploring of Influence of Boron on Acidity of Organic Functional Groups by DFT Calculation
, M.Sc. Thesis Sharif University of Technology ; Fattahi, Alireza (Supervisor)
Abstract
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...
Study of NxOy Macrocycles Bearing Peripheral Functional Groups as Axial Ligands of Zinc Tetraphenylporphyrin
, M.Sc. Thesis Sharif University of Technology ; Ghanbari, Bahram (Supervisor)
Abstract
In this project, M2 macrocyclic ligand, bearing three pyridine side arms (3p) was synthesized and characterized by employing elemental analysis and 1H NMR, 13C NMR and IR methods. The interaction of 3p with zinc tetraphenylporphyrin was investigated, using fluorescence and UV-vis spectroscopy in solution phase. The observed quenching in the fluorescence spectrum alongside Q band shift in UV-vis spectrum indicate on the interaction of 3p with ZnTPP. The formation constant for these interactions in 1:1 ratio was calculated 10100 M-1, employing fluorescence method. The formation constant was calculated 630 M-1 for 1:2 ratio for 3p:ZnTPP. Having 1:2 ratio 3pZnTPP was also synthesized and...
Experimental Study of Using Cellulosic Compounds in Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Manouchehr (Supervisor) ; Karimi, Afzal (Supervisor) ; Faghihi, Faezeh (Co-Supervisor)
Abstract
Fabrication and characterization of different surface charged cellulose electrospun scaffolds including cellulose acetate, cellulose, carboxymethyl cellulose and quaternary ammonium cationic cellulose for biomedical applications have been reported in this research. We describe preparation of cellulosic nanofibers through the electrospinning following deacetylation cellulose acetate. Moreover, surface modification of electrospun cellulose nanofibers is carried out to obtain carboxymethyl cellulose and quaternized cellulose nanofibers, respectively. At last, the structural, morphological, mechanical, swelling, wettability and the cell culture properties of the scaffolds were analyzed and...
H 2 adsorption mechanism in Mg modified multi-walled carbon nanotubes for hydrogen storage
, Article International Journal of Hydrogen Energy ; Volume 37, Issue 2 , January , 2012 , Pages 1919-1926 ; 03603199 (ISSN) ; Mortazavi, S. Z ; Mirershadi, S ; Golikand, A. N ; Moshfegh, A. Z ; Sharif University of Technology
Abstract
Multi-walled carbon nanotubes (MWCNTs) with diameter of about 50 nm were synthesized using thermal chemical vapor deposition. We have investigated the influence of Mg doping to the MWCNTs on its hydrogen storage property. TEM micrographs showed that Mg was attached to the MWCNTs and discontinuous arrangement of the carbon walls was recognized in the MWCNTs. According to XPS and BET analyses, the surface functional groups and pore size of the Mg-MWCNTs are increased by interactions between the Mg and the MWCNT's outer walls. The electrochemical discharging curves of the MWCNTs and Mg-doped MWCNTs revealed that the hydrogen storage capacity was 363 and 450 mAhg -1, respectively. Volumetric...
Coordination Investigation of Macrocyclic Ligands Tertiary Amine Groups with [60] Fullerene and Cu(II)
, M.Sc. Thesis Sharif University of Technology ; Ghanbari, Bahram (Supervisor)
Abstract
The reaction of O2N2-donor naphthodiazacrown, with salicylaldehyde afforded new O3N2-donor macrocyclic ligands (L1-3naph) mounted with 1,3-diazcyclohexane subring in high yield. The product was characterized by IR, 1HNMR spectroscopy as well as elemental microanalysis and single crystal X-ray studies (just for L3naph). The interactions of [60]fullerene in presence and absence of base, Cu(II), Hg(II) and Zn(II) with L1-3naph were investigated employing fluorescence spectroscopy. The efficient fluorescence quenching of L1-3naph in presence of C60, Cu(II)( L1-2naph) and the fluorescence enhancement in presence of Hg(II) and Zn(II) indicated that the interaction with [60]fullerene Hg(II) and...
Theoretical Investigation of Hydrogen Bonding Effects on Acidity Enhancement of Beta Diketones in Gas and Solution Phase
, M.Sc. Thesis Sharif University of Technology ; Fattahi, Alireza (Supervisor) ; Mahmoodi Hashemi, Mohammad (Supervisor)
Abstract
Hydrogen bonding is an important weak interaction encountered in gas and liquid, as well as solid phase. The hydrogen bond plays a very vital role in many life processes and is one of the most frequently used terms in chemistry and biology. Beta diketones have several applications in organic, inorganic and analytical chemistry. Different substituents can affect the acidity of beta diketones. Investigation have shown that hydroxyl function group can increase the acidity of many organic molecules through interamolecular hydrogen bonding. The goal of this project is to investigate the acidity of hydroxyl containing beta diketones in the gas and solution phase. All the gas phase optimizations...
Accelerated Oil Droplet Separation from Produced Water Using Magnetic Nanoparticles
, M.Sc. Thesis Sharif University of Technology ; Shayegan, Jalaleddin (Supervisor)
Abstract
Removal of petroleum hydrocarbons from water is one of the environmental challenges. In this study the functionalized magnetic nanoparticles (MNPs) was used to remove kerosene oil as contaminants from water. Effective factors on adsorption of oil on MNPs were investigated. Magnetic nanoparticles were synthesized on activated carbon derived from almond shell and after a coating by silica, it Was functionalized by NH2 and COOH functional groups. After preparation of kerosene oil/water stable emulsions by emulsifier, the adsorption capacity of AC@Fe3O4@SiO2-NH2-COOH was evaluated. The adsorbent was characterized by various physicochemical techniques such as transmission electron microscopy,...
Investigation of Chemical Factors Affecting on Supramolecular Chemistry of Gas Hydrate Inhibitors
, M.Sc. Thesis Sharif University of Technology ; Ghanbari, Bahram (Supervisor) ; Taheri Rizi, Zahra (Supervisor)
Abstract
In this research, some inhibitors based on quaternary monoammonium salts and quaternary diammonium salts containing different anions were synthesized to prevent formation of methane gas hydrates, and they were characterized using 1H and 13C NMR spectra, IR spectroscopy, elemental analysis and mass spectrometry. Then, the synthesized compounds were used in an autoclave under 128 bar pressure under controlled isothermal conditions to determine retention time considering displacement amount of the gas hydrate temperature- pressure chart and also to determine subcooling of the samples using HW Hydrate software. According to the results T3, T4 and TBAHF compounds in their pure form, not only...
Extension of linear isotherm regularity to long chain primary, secondary and tertiary alcohols, ketones and 1-carboxylic acids by group contribution method
, Article Fluid Phase Equilibria ; Volume 234, Issue 1-2 , 2005 , Pages 11-21 ; 03783812 (ISSN) ; Kalantar, Z ; Sharif University of Technology
2005
Abstract
In this work, the group contribution approach has been used in combination with the linear isotherm regularity (LIR) equation of state to estimate pvT properties of primary, secondary and tertiary alcohols, ketones and 1-carboxylic acid. In addition, the isothermal compressibility and thermal expansion coefficient of these compounds have been predicted. We assume each of these organic compounds as a hypothetical mixture of methyl, methylene and a functional group, in which the interaction potential of each pair is assumed to be the average effective pair potential. Then, the LIR equation of state (EOS) has been extended to such a hypothetical mixture. Three basic compounds, namely propane,...
Thermal, mechanical and acoustic damping properties of flexible open-cell polyurethane/multi-walled carbon nanotube foams: Effect of surface functionality of nanotubes
, Article Polymer International ; Volume 60, Issue 3 , NOV , 2011 , Pages 475-482 ; 09598103 (ISSN) ; Shojaei, A ; Rashidi, A. M ; Sharif University of Technology
Abstract
This article demonstrates the properties of open-cell flexible polyurethane foams incorporating multi-walled carbon nanotubes. Three different types of highly functionalized nanotubes having carboxyl, hydroxyl and amide functional groups were synthesized. Neat polyurethane foam and three nanocomposite foams filled with 0.1 wt% of treated nanotubes were prepared. It was found that thermal stability, mechanical properties and acoustic damping were improved significantly by incorporation of small amounts of nanotubes. The nanotubes modified with carboxyl groups were found to have much more influence compared to the other two functional groups, possibly due to better interfacial interaction and...
Solvothermal synthesis of CuMS2 (M=A1, In, Fe) nanoparticles and effect of coordinating solvent on the crystalline structure
,
Article
Scientia Iranica
;
Volume 21, Issue 6
,
2014
,
Pages 2468-2478
;
ISSN: 10263098
; Ghasemzadeh, R
; Zad, A. I
; Mirkazemi, S. M
; Masoud, A
;
Sharif University of Technology
Abstract
CuMS2 (M=A1, In, Fe) ternary compounds were synthesized via the facile polyol method in autoclave. Depending on the functional groups of solvent and surfactant, the structure of the nanocrystals can be controlled in the form of wurtzite or chalcopyrite. The chalcopyrite structure was obtained when the precursors solved in the mixture of diethylene glycol, polyethylene glycol 600 and ammonium hydroxide. When the solvent was replaced by ethylene diamine, the wurtzite was obtained along with chalcopyrite (polytypism). The products were characterized by X-Ray Diffraction (XRD) for analysis of structural properties, Transmission Electron Microscopy (TEM) for studying morphological...
Halide (Cl-, Br-, I-) influence on the electronic properties of macrocyclic nickel(II) complexes: Ab-initio DFT study
, Article Journal of the Korean Chemical Society ; Volume 57, Issue 3 , 2013 , Pages 311-315 ; 10172548 (ISSN) ; Akhtari, K ; Hassanzadeh, K ; Piltan, M ; Saaidpour, S ; Abedi, M ; Sharif University of Technology
2013
Abstract
The geometry structures of hexa-coordinated [NiLX]X complexes (X = Cl -, Br-, I-) {L = 8,9,18,19-tetrahydro-7H,17H- dibenzo[f,o] [1,5,9,13]dioxadiaza cyclohexadecine-8,18-diol} are optimized by density functional theory (DFT) using B3LYP/LANL2DZ. The calculated geometric parameters are in good agreement with the corresponding experimental values. Calculation results about these complexes show that dipole moment decreases, and the energy levels of HOMOs descend from iodo-complex to chloro-complex. The energy levels of HOMOs descend gently from iodo-complex to chloro-complex, while the energy levels of LUMOs in the present complexes are almost similar; therefore the energy gapes between HOMOs...
Escherichia coli bacteria reduce graphene oxide to bactericidal graphene in a self-limiting manner
, Article Carbon ; Volume 50, Issue 5 , 2012 , Pages 1853-1860 ; 00086223 (ISSN) ; Ghaderi, E ; Sharif University of Technology
2012
Abstract
Interactions of chemically exfoliated graphene oxide (GO) nanosheets and Escherichia coli bacteria living in mixed-acid fermentation with an anaerobic condition were investigated for different exposure times. X-ray photoelectron spectroscopy showed that as the exposure time increased (from 0 to 48 h), the oxygen-containing functional groups of the GO decreased by ∼60%, indicating a relative chemical reduction of the sheets by interaction with the bacteria. Raman spectroscopy and current-voltage measurement confirmed the reduction of the GO exposed to the bacteria. The reduction was believed to be due to the metabolic activity of the surviving bacteria through their glycolysis process. It was...
Wrapping bacteria by graphene nanosheets for isolation from environment, reactivation by sonication, and inactivation by near-infrared irradiation
, Article Journal of Physical Chemistry B ; Volume 115, Issue 19 , 2011 , Pages 6279-6288 ; 15206106 (ISSN) ; Ghaderi, E ; Esfandiar, A ; Sharif University of Technology
American Chemical Society
2011
Abstract
Bioactivity of Escherichia coli bacteria (as a simple model for microorganisms) and interaction of them with the environment were controlled by their capturing within aggregated graphene nanosheets. The oxygen-containing functional groups of chemically exfoliated single-layer graphene oxide nanosheets were reduced by melatonin as a biocompatible antioxidant. While each one of the graphene (oxide) suspension and melatonin solution did not separately show any considerable inactivation effects on the bacteria, aggregation of the sheets in the melatonin-bacterial suspension resulted in trapping the bacteria within the aggregated sheets, i.e., a kind of inactivation. The bacteria trapped within...
Experimental design for optimizing the corrosion resistance of pulse reverse electrodeposited graphene oxide thin film
, Article Journal of Solid State Electrochemistry ; Volume 19, Issue 5 , May , 2015 , pp 1367–1380 ; 14328488 (ISSN) ; Afshar, A ; Sharif University of Technology
Springer New York LLC
2015
Abstract
In this study, linear polarization resistance (LPR) of pulse reverse electrodeposited graphene oxide (PREGO) coating is optimized by design of experiments approach (central composite design). Pulse current density (i), cathodic (Tc) and anodic (Ta) pulse durations, and total electrodeposition time (Tt) are selected as the substantial factors. The best prediction model proposes a definitive linear relation without any significant interaction of the LPR by analysis of variance. The desirable value of LPR was predicted equal to 5358 Ω cm2, obtaining at the pulse current density of 235.62 mA cm−2, Ta of 7.75 ms, Tc equal to 3.25 ms (f = 100 Hz), and Tt of approximately 225 s. Appearance of the...
Epoxidation of olefins catalyzed by some cis-dioxomolybdenum(VI)-tridentate schiff base complexes with tert-butyl hydroperoxide
, Article Scientia Iranica ; Volume 17, Issue 2 C , 2010 , Pages 131-138 ; 10263098 (ISSN) ; Ghazali Esfahani, S ; Sharif University of Technology
2010
Abstract
Some cis-dioxomolybdenum (VI) complexes with tridentate Schiff base ligands derived from salicylaldehyde and aminophenols, aminoalcohol or o-aminobenzenethiol were examined as catalysts for epoxidation of different aliphatic and aromatic olefins, with tert-butyl hydroperoxide as oxidant. All complexes exhibited high activity and selectivity for epoxidation of aliphatic substrates during a short time period (95% conversion of cyclooctene after 30 min). The epoxide yield increased with the nucleophilic character of olefin. The catalysts activation strongly depends on the reaction temperature and nature of the solvent. Epoxidation of olefins by these catalysts is inhibited by ligands or...
H2S gasochromic effect of mixed ammonium salts of phosphomolybdate nanoparticles synthesized by microwave assisted technique
, Article Sensors and Actuators, B: Chemical ; Volume 237 , 2016 , Pages 715-723 ; 09254005 (ISSN) ; Iraji zad, A ; Tadjarodi, A ; Sharif University of Technology
Elsevier B.V
2016
Abstract
In the present paper, new H2S gasochromic nanomaterial of mixed silver nickel ammonium phosphomolybdate synthesized by microwave assisted technique is reported. The microwave treatment was performed in the solid phase using urea and ammonium nitrate as the promoter and oxidizer agents. The designed process allows rapid synthesis of large amounts of this product in nanosized particulate morphology. Morphological and structural features of the prepared products were studied in detail. Chemical analyses indicated a stoichiometry of (NH4)0.5Ni0.75AgPMo12O40·4H2O revealing a Keggin-type framework with substitution of silver and nickel cations in its secondary structure. A home-made set-up was...
TPU/graphene nanocomposites: effect of graphene functionality on the morphology of separated hard domains in thermoplastic polyurethane
, Article Polymer ; Volume 148 , 18 July , 2018 , Pages 169-180 ; 00323861 (ISSN) ; Pircheraghi, G ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Graphene nanoplatelets with different surface functional groups and polarity were prepared by Hummer's method and electrochemical exfoliation of graphite in two aqueous acids. The XRD, FTIR and sedimentation tests performed to characterize the polarity of the prepared graphenes. The highest polarity was associated with the sample prepared by Hummer's method and the sample synthesized by electrochemical exfoliation in nitric acid medium showed the moderate polarity. Meanwhile, the sample prepared in sulfuric acid medium showed the lowest polarity. Then thermoplastic polyurethane (TPU)/graphene nanocomposite films were fabricated with solvent exchange method. While the dispersion state and...
Stochastic modeling of degradation behavior of hydrogels
, Article Macromolecules ; Volume 51, Issue 11 , 2018 , Pages 3941-3952 ; 00249297 (ISSN) ; Abdekhodaie, M. J ; Chau, Y ; Sharif University of Technology
American Chemical Society
2018
Abstract
We describe here a theoretical framework to model the bulk degradation of hydrogels, which are prepared by chemical cross-linking of pendant functional groups on long polymer chains. The random order of the cleavage of degradable bonds was described by stochastic Monte Carlo simulation. The events of bond cleavage were related to the macroscopic changes of hydrogel by the Bray-Merrill equation. Next, the time for the gel to disintegrate was predicted by considering the relation between the recursive nature in breaking the cross-link nodes and gel-to-sol transition. To start the simulation, initial network properties including the number of active functional groups on the polymer chain and...