Sharif Digital Repository

In this study, the synthesis and characterization of a novel nano-porous superabsorbent hydrogel with high water swelling capacity is described. A nano-porous hydrogel was prepared by employing (2-dimethylaminoethyl) methacrylate (PDMAEMA) as a pH sensitive monomer and sodium alginate (SA) as a water soluble polysaccharide under γ-ray irradiation. The polymerization reaction was performed at room temperature in the absence of chemically toxic crosslinking agent and initiators. The interactive parameters including biopolymer backbone concentration, monomer concentration and γ-irradiation dose were selected as major factors in the synthesis of superabsorbent and three levels for each factor... 

Desalting plants are often installed in crude oil production units in order to remove water-soluble salts from an oil stream. Experiments in both the laboratory and field have shown the desalting process parameters to be very complicated. This research reflects the results of a study conducted regarding the impact of operational desalting parameters, including the effects of temperature, injected chemicals and the pH of the crude oil associated water, on an electrostatic desalter on one of the oil platforms owned by the Iranian Oil Offshore Company in the Persian Gulf. The temperature range applied was between 98 to 133 °C, at which the effects on water and oil density as well as salt... 

The solubility of sulfur dioxide (SO2) and carbon dioxide (CO2) at P = 1 bar in a series of imidazolium-based room-temperature ionic liquids (RTILs) is calculated by Monte Carlo simulation in NPT ensemble using the OPLS-UA force field and Widom particle insertion method. The studied ILs were 1-butyl-3-methylimidazolium ([bmim]+) tetrafluoroborate ([BF4]-), [bmim]+ hexafluorophosphate ([PF 6]-), [bmim]+ bromide ([Br]-), [bmim]+ nitrate ([NO3]-), [bmim]+ bis-(trifluoromethyl) sulfonylimide ([Tf2N]-), and 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]). To validate the simulations, the liquid density of studied ILs and the solubility of CO2 in [bmim][PF6] was compared with... 

Iron oxide nanoparticles, γ-Fe2O3NP, were deposited onto the surface of multi-walled carbon nanotubes and CNT/γ-Fe2O3NP hybrid nanomaterials were obtained. Then linear-dendritic ABA type block copolymers consisting of polyethylene glycol as B block and poly(citric acid) as A block, PCA-PEG-PCA, were synthesized and cisplatin (cis-diamminedichloroplatinum (CDDP) - a platinum-based chemotherapy drug) was conjugated with their carboxyl functional groups and CDDP/PCA-PEG-PCA anticancer prodrugs were prepared. Noncovalent interactions between CDDP/PCA-PEG-PCA anticancer prodrugs and CNT/γ-Fe2O3NP hybrid nanomaterials led to CDDP/PCA-PEG-PCA/CNT/γ-Fe2O3NP drug delivery systems. There are several... 

The synthesis of a new drug delivery system based on hybrid nanomaterials containing a β-CD core and hyperbranched PG is described. Conjugating PG branches onto β-CD not only increases its water solubility but also affects its host/guest properties deeply. It can form molecular inclusion complexes with small hydrophobic guest molecules such as ferrocene or FITC with reasonable release. In addition, the achievable payloads are significantly higher as for carriers such as hyperbranched PGs. Short-term in vitro cytotoxicity and hemocompatibility tests on L929 cell lines show that the hybrid nanomaterial is highly biocompatible. Due to their outstanding properties, β-CD-g-PG hybrid nanomaterials... 

There are increasing evidences that adjusting the chemistry of the injecting water improves the oil recovery efficiency. However, the underlying mechanisms for this technique which is referred to as "smart waterflood" have not yet been thoroughly understood. It is needed to explore the role of individual ions through set of different tests, to find the right mechanisms behind "smart waterflood". This study is focused on the fluid/solid (carbonate) interactions through systematic wettability measurement. Contact angle measurements accompanied by spontaneous imbibition tests were employed to determine the role of individual monovalent and divalent ions in wettability alteration process by... 

The bioconversion of abundant and renewable cellulosic biomass into ethanol as an alternative to petroleum is gaining importance due to the realization of diminishing natural oil and gas resources. Agricultural and foresty plant residues are an abundant and renewable source of sugar substrates that could be fermented to ethanol. A thermochemical treatment of biomass in which both cellulose and hemicellulose are hydrolyzed to soluble sugar is necessary before yeast fermentation. After thermochemical treatment, cellulase enzymes must be introduced in the system to hydrolyze any remaining cellulose. The simultaneous saccharification and fermentation (SSF), is a method which converts... 

Homopolymer hydrogel of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and its nanocomposite counterpart were prepared to study their swelling properties. The hydrogels showed ability to absorb and retain electrolytes as well as binary mixtures of water and organic solvents (i.e., methanol, ethanol, acetone, ethylene glycol (EG), polyethylene glycol, N-methyl-2-pyrrolidone (NMP), and dimethylsulfoxide (DMSO). The nanocomposite gel exhibited lower swelling in all solvent compositions in comparison with non-composite gel. Unlike conventional acrylic acid-based hydrogels, the poly(AMPS) gels showed superabsorbing capacity in pure ethanol, methanol, EG, DMSO and NMP. Meanwhile, swelling... 

In this study, degradation of trichloroethylene (TCE), a chlorinated hydrocarbon, using starch supported Fe/Ni nanoparticles was investigated. The scanning electron microscope images showed applying water soluble starch as a stabilizer for the Fe/Ni nanoparticles tended to reduce agglomeration and discrete particle. Also the mean particle diameter reduced from about 70 nm (unsupported Fe/Ni nanoparticle) to about 30 nm. Effects of three key independent operating parameters including initial TCE concentration (10.0-300.0 mg L-1), initial pH (4.00-10.00) and Fe0 dosage (0.10-2.00) g L-1 on TCE dechlorination efficiency in 1 hour were analysed by employing response surface methodology (RSM).... 

In recent years miscellaneous smart micro/nanosystems that respond to various exogenous/endogenous stimuli including temperature, magnetic/electric field, mechanical force, ultrasound/light irradiation, redox potentials, and biomolecule concentration have been developed for targeted delivery and release of encapsulated therapeutic agents such as drugs, genes, proteins, and metal ions specifically at their required site of action. Owing to physiological differences between malignant and normal cells, or between tumors and normal tissues, pH-sensitive nanosystems represent promising smart delivery vehicles for transport and delivery of anticancer agents. Furthermore, pH-sensitive systems... 

New dual light/temperature-responsive nanocarriers were synthesized using bimetallic plasmonic Au-Ag and Ag-Au nanoparticles (NPs) as cores of vehicles which subsequently functionalized with an upper critical solubility temperature–based poly acrylamide-co-acrylonitrile using reversible addition-fragmentation chain transfer for spatiotemporally controlled chemo-photothermal synergistic cancer therapy. The bimetallic cores were assigned to sense wavelengths close to the localized surface plasmon resonance of monometallic NP shell to produce heat which not only can increase the surrounding temperature over the upper critical solubility temperature of polymer to open its valves and promote drug... 

Comprehensive structural/molecular simulations have been undertaken to study the poly(benzimidazoles) (PBI) membrane combined with four different nano-oxide materials (ZnO, Al2O3, SiO2 and TiO2) for purification and production of hydrogen from natural gases. Composite membranes were built with different amounts of nano-oxide materials to investigate the influence of nano-oxide content on the PBI membrane performance. Several structural characterizations such as FFV, WAXD and also a thermal one (glass transition temperature) were done to study the structural properties of all simulated membrane cells. Moreover, MSD and adsorption isotherms tasks were used to estimate the diffusivity and... 

Deep wells suffer from the instability and disintegration of natural polymers and other commonly used additives under high pressure and high temperature condition. As a result, serious problems such as hydraulic loss, stuck pipe, and high torque and drag are expected to take place which leads to a dramatic increase in cost and time. This study presents the functionality of a novel synthetic based acrylamide-styrene copolymer (SBASC) as a supersede additive for water-based drilling mud. First, the SBASC was synthesized using an emulsion polymerization process and its particle morphological and polymer chain structural properties were determined by Field Emission Scanning Electron Microscopy... 

Unique physiochemical and biological properties of nanofibers along with the choice of a wide variety of materials for both fabrication and tunable release patterns make nanofibers an ideal option for drug delivery. Loading antibacterial agents into nanofibers has attracted great deal of attention. Whilst there are several studies focusing on applying new generations of antibacterial materials, antibiotics are still the gold standard in clinical applications. Therefore, we aimed at introducing antibiotic-loaded nanofiber substrates with potential for topical skin delivery applications, reduced consumption of antibiotics and increased storage time. We applied Amoxicillin (AMX) as a model drug... 

Objective(s): Bioresorbable scaffolds have been advocated as the new generation in interventional cardiology because they could provide temporary scaffolds and then disappear with resorption. Although, the available stents in clinical trials exhibited biosafety, efficacy, no death, and no apparent thrombosis, Mg-substrate degradation on drug release has not been investigated. Materials and Methods: Therefore, more research has been needed to legitimize the replacement of current stents with Mg-based stents. UV-Vis spectrophotometer, scanning electron microscope (SEM), X-ray diffraction (XRD), pH measurement, H2 evolution, and corrosion tests determined the change in hybrid properties and... 

Because of the recent frequent observations of major dust storms in southwestern cities in Iran such as Ahvaz, and the importance of the ionic composition of particulate matters regarding their health effects, source apportionment, etc., the present work was conducted aiming at characterizing the ionic composition of total suspended particles (TSP) and particles on the order of ∼10 μm or less (PM10) during dust storms in Ahvaz in April-September 2010. TSP and PM10 samples were collected and their ionic compositions were determined using an ion chromatography. Mean concentrations of TSP and PM10 were 1,481.5 and 1,072.9 μg/m 3, respectively. Particle concentrations during the Middle Eastern... 

Integrally skinned asymmetric membranes for the separation of O 2 and N 2 were fabricated by the phase inversion technique from polysulfone, polyetherimide, and polyimide. Two types of surface modifying macromolecules (SMMs) including hydrophilic SMM (LSMM) and charged SMM (cSMM) were synthesized and blended with the casting solution to modify the membrane surface. The cast film was then immersed in the first coagulant alcohol (methanol, ethanol, or isopropanol) for a predetermined period, before being immersed in the second coagulant (water). The SMMs used in these experiments were laboratory synthesized by the two-step process of polyurethane prepolymer synthesis and end capping, before... 

Equations of state based on the statistical associating fluid theory for potentials of variable range (SAFT-VR) and the perturbed chain statistical associating fluid theory (PC-SAFT) have been used to model the PVT behavior of ionic liquids and the solubility of H2S in six imidazolium-based ionic liquids. The studied systems included [bmim][PF6], [hmim][PF6], [bmim][BF4], [hmim][BF4], [bmim][NTF2] and [hmim][NTF2] at various temperatures and pressures.For pure components, parameters of the models have been obtained by fitting the models to experimental data on liquid densities; the average relative deviation between the calculated and experimental densities for ionic liquids is less than... 

Background: The bio-oxidation of ferrous iron is a potential industrial process in the regeneration of ferric iron and the removal of H2S in combustible gases. Bio-oxidation of ferrous iron may be an alternative method of producing ferric sulfate, which is a reagent used for removal of H2S from biogas, tail gas and in the pulp and paper industry. For practical use of this process, this study evaluated the optimal pH and initial ferric concentration. pH control looks like a key factor as it acts both on growth rate and on solubility ofmaterials in the system. Results: Process variables such as pH and amount of initial ferrous ions on oxidation by A. ferrooxidans and the effects of process... 

The potential of electrospun cellulose acetate/chitosan/single walled carbon nanotubes/ferrite/titanium dioxide (CA/chitosan/SWCNT/Fe3O4/TiO2) nanofibers was investigated for the removal of Cr(VI), As(V), Methylene blue and Congo red from aqueous solutions via the adsorption and photocatalytic reduction processes. The properties of synthesized SWCNT/Fe3O4/TiO2 and fibers were characterized using TEM, SEM, FTIR, XRD, TGA and BET analysis. In adsorption process, the influence of adsorbent type including SWCNT to Fe3O4 ratio, TiO2 to SWCNT/Fe3O4 ratio and SWCNT/Fe3O4/TiO2 concentration as well as the adsorption parameters including pH, contact time, and initial concentration of adsorbates on...