Sharif Digital Repository

In this paper, the dissolution and mobilization of non-aqueous phase liquid (NAPL) blobs in the Surfactant-Enhanced Aquifer Remediation (SEAR) process were upscaled using dynamic pore network modeling (PNM) of three-dimensional and unstructured networks. We considered corner flow and micro-flow mechanisms including snap-off and piston-like movement for two-phase flow. Moreover, NAPL entrapment and remobilization were evaluated using force analysis to develop the capillary desaturation curve (CDC) and predict the onset of remobilization. The corner diffusion mechanism was also applied in the modeling of interphase mass transfer to represent NAPL dissolution as the dominant mass transfer... 

Rhamnolipids are the most common biosurfactants and P. aeruginosa strains are the most frequently studied microorganisms for the production of rhamnolipids. Eco-friendly advantages and promising applications of rhamnolipids in various industries are the major reasons for pursuing the economic production of these biosurfactants. This study shows that cultivation of P. aeruginosa MR01 in medium contained inexpensive soybean oil refinery wastes which exhibited similar levels and homologues of rhamnolipids. Mass spectrometry indicated that the Rha-C10-C10 and Rha-Rha-C10-C10 constitute the main rhamnolipids in different cultures of MR01 including one of oil carbon source analogues. Moreover,... 

This investigation is conducted on one of the southern Iranian oil fields, which experiences a fault on its gas cap. Therefore, no traditional gas injection and normal water injection for pressure maintenance is suggested. The target is set to inject special compatible and proper type of chemicals in each single well to avoid the pressure increase for the risk of oil and gas spill. Two different sources of aqueous phases, namely formation brine and sea water were used to find the effects of different brine composition on the main mechanisms of releasing the trapped oil, interfacial tension (IFT) and wettability alteration. The obtained results reveal that both the ionic liquid (IL) based... 

This study aims to design photo-triggered micelles by using a natural base polymer. Chitosan was functionalized with thiourea, and in the next step, it was modified by grafting poly(L-lactide), poly(N-isopropylacrylamide), and poly(acrylamide) in determined ratio to form thermo-sensitive micelles. The sulfur content of chitosan@thiourea was measured about 2%. Grafting of polymers on chitosan was characterized by FT-IR and NMR techniques. The critical micellar concentration was measured by using photo luminescence spectroscopy. The size and surface morphology experiments revealed that average size of micelles is about 14 nm, and the length and width of GNRs are about 65 and 19 nm,... 

This research aims to propose a thermodynamic model for predicting asphaltene precipitation upon diluting a crude oil with a paraffinic solvent. To this end, a thorough mathematical formulation was carried out to derive a novel micellization model based on the associative properties of asphaltenic compounds. It was assumed that asphaltenes exist in the oil both as monomeric molecules and aggregated cores; with stabilization latter by attachment of resin on its periphery. The aggregation equilibrium was established by taking into account asphaltene's lyophobic tendency, heat of resin adsorption, and interfacial tension between micelle and oil media which is the main driving factor... 

This review highlights using nanotechnology in increasing the bioavailability of AP (Apigenin) to enhance its therapeutic efficacy in breast cancer treatment. Breast cancer is one of the most leading causes of cancer death in women both in developed and developing countries. According to several epidemiological and clinical trial studies that indicate progestin-stimulated breast cancer in post-menopausal women; it is necessary to determine compounds to suppress or attenuate the tumor-promoting effects of progestins in breast cells. For this purpose, using the natural anti-progestins, including AP compared with the chemical ones could be significantly effective due to the lack of toxicities... 

Throughout the world, cancer is one of the main causes of mortality, threatening the public health in many countries. As a result, cancer therapy researchers are paying increasing attention to biocompatible targeted drug delivery systems. Nanocarriers and co-delivery of active drugs is emerging as an essential research field for improving therapeutic efficiency. Although nutraceuticals are now being used to prevent and treat chronic illnesses such as cancers, some have shown limitations concerning solubility, bioavailability, and biodegradability. This review explores different types of nanostructures that can be used as drug delivery systems for curcumin, a biologically active polyphenol... 

Background: Smart stimulus-responsive nanocarriers represent a rapidly growing class of drug-delivery systems for cancer and other diseases. Objective: The alterations of redox potential between the intracellular environment and the extracellular space have been widely utilized as a trigger for delivery of therapeutic agents by smart stimulus-responsive nanocarriers. We set out to review the scientific literature. Method: Published papers between 1980 and the present day were surveyed. Results: The advantages of redox-activated smart delivery of drugs, genes, and imaging agents include: the amplitude of the redox-responsive signal; the simple chemical features needed to trigger the... 

The critical micelle concentration (CMC) of a set of 30 alkyltrimethylammonium [RN+(R′)3X-] and alkylpyridinium salts [RN+φX-] was related to topological, electronic, and molecular structure parameters using a stepwise regression method. Among different models obtained, two equations were selected as the best and their specifications are given. The statistics for these models together with the crossvalidation results indicate the capability of both models to predict the CMC of cationic surfactants. The results obtained for alkyltrimethylammonium salts indicate that geometric characteristics such as volume of the tail of the molecule, maximum distance between the atoms, and surface area play... 

Catecholamine neurotransmitters, specifically, dopamine (DA), epinephrine (EP), and norepinephrine (NE), are known as substantial indicators of various neurological diseases. Developing rapid detection methods capable of simultaneously screening their concentrations is highly desired for early clinical diagnosis of such diseases. To this aim, we have designed an optical sensor array using three fluorescent dyes with distinct emission bands and have monitored variations in their emission profiles upon the addition of DA, EP, and NE in the presence of gold ions. Because of the different reducing power of catecholamines, differently sized gold nanoparticles (GNPs) with different levels of... 

In this paper, the performance of three imidazolium-based ionic liquids (ILs) including 1-hexyl-3-methylimidazolium chloride ([HMIM][Cl] or IL6), 1-octyl-3-methylimidazolium chloride ([OMIM][Cl] or IL8), and 1- dodecyl-3-methylimidazolium chloride ([DMIM][Cl] or IL12) in reducing the interfacial tension (IFT) between crude oil and IL solutions was analyzed for the first time under a wide range of salinities (1000 to 195 476 ppm) at a reservoir temperature of 80 °C. The purpose was to microscopically analyze the occurring phenomenon at the fluid-fluid interface to determine the mechanism leading to oil extraction and to address the existing ambiguities in the literature concerning the... 

The oxidation-reduction (redox)–responsive micelle system is based on a diselenide-containing triblock copolymer, poly(ε-caprolactone)-bis(diselenide-methoxy poly(ethylene glycol)/poly(ethylene glycol)-folate) [PCL-(SeSe-mPEG/PEG-FA)2]. This has helped in the development of tumor-targeted delivery for hydrophobic anticancer drugs. The diselenide bond, as a redox-sensitive linkage, was designed in such a manner that it is located at the hydrophilic–hydrophobic hinge to allow complete collapse of the micelle and thus efficient drug release in redox environments. The amphiphilic block copolymers self-assembled into micelles at concentrations higher than the critical micelle concentration (CMC)... 

A fundamental chemical enhanced oil recovery (EOR) process is surfactant flooding in which the key mechanism is to reduce interfacial tension between oil and the displacing fluid and hence mobilizing the trapped oil. Surfactant loss by adsorption is one of the most important criteria that governs the economics of the surfactant flooding methods. In addition to this, detrimental effects and high price of currently used surfactants cause EOR process so expensive and unfeasible. This study is aimed to introduce a novel kind of plant based surfactant which is extracted from Zizyphus Spina-Christi tree. In addition, equilibrium adsorption behavior of this novel biosurfactant in aqueous solution... 

In this paper, the well-known effective medium approximation (EMA) and coupled dipole approximation (CDA) methods are employed to study the optical properties of a metal nanoparticle-block copolymer (MNP-BCP) nanocomposite. This approach is applied to study a system consisting of small gold spherical nanoparticles randomly distributed in the cylindrical micelles of a di-BCP. At first, the EMA method is used to obtain the effective dielectric function of a semi-metallic cylinder. Then, the extinction spectrum of the hexagonal 2D-array of semi-metallic cylinders is obtained by the CDA method. This procedure makes it possible to study simultaneously both the electromagnetic extinction of MNPs... 

A simple, rapid and sensitive method based on microextraction in packed syringe (MEPS), in combination with gas chromatography-mass spectrometry (GC-MS) was developed. Polyaniline (PANI) nanowires network was synthesized and used as sorbent of MEPS for the multiresidue determination of selected analytes from triazine, organochlrorine and organophosphorous pesticides in aqueous samples. The PANI nanowires network was prepared using soft template technique and its characterization was studied by scanning electron microscopy (SEM). The presence of micelles in this methodology showed to be an important parameter in shaping the growing polymer. Hexadecyltrimethylammonium bromide (HTAB) was used... 

A novel method based on microextraction in packed syringe (MEPS), as a sample preparation technique in combination with gas chromatography-mass spectrometry (GC-MS) was developed using a polypyrrole (PPy) nanowires network as the extracting medium. The PPy nanowires network was prepared using a soft template technique and its characterization was studied by scanning electron microscopy (SEM). The use of micelles in this methodology has an important role in the shape of the growing polymer. The pyrrole monomer was introduced into cetyltrimethylammonium bromide (CTAB) micelles and this has led to the formation of nanowires with diameters ranging from 30 to 60 nm. The bulk PPy prepared without... 

Molecular dynamics simulations are performed to obtain insight into the structural properties of hydrated Nafion using the sandwich model of the polymer membrane. It is shown that a larger distance between the sulfonate groups of a chain leads to the polymer forming a better inverted micelles structure. Water- and hydronium-polymer interfaces are investigated. Comparing our results with others indicates that, from the perspective of distance, the formation of shells of water and hydronium ions is independent of the model and monomer type, but depends on both if the coordination number is considered. The behaviour of water molecules and hydronium ions is also studied dynamically. Our survey... 

Effects of initiator and surfactant concentrations and temperature on styrene conversion and polymer particle size distribution (PSD) in a batch emulsion polymerization are investigated through simulation and experimental studies. The detailed model based on population balance (zero-one model), accounting for nucleation, growth and coagulation phenomena has been used for prediction of particle size distribution. In checking the effect of initiator concentration on final PSD, it was noticed that when critical micelle concentration (CMC) is kept constant, the model cannot predict PSD very well. Thus, a correlation for calculating critical micelle concentration has been proposed and... 

Core-shell iron-gold (Fe@Au) nanoparticles were synthesized by a facile reverse micelle procedure and the effect of water to surfactant molar ratio (w) on the size, size distribution and magnetic properties of the nanoparticles was studied. MTT assay was utilized to evaluate the cell toxicity of the nanoparticles. To functionalize the particles for MRI imaging and targeted drug delivery, the particles were coated by polyglycerol through capping with thiol followed by polymerization of glycidol. The characteristics of the particles were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometere (VSM), UV-visible spectroscopy, and Fourier... 

In this research, we report a magnetic pH-sensitive polymeric micelle designed for hydrophobic drug carrier in cancer treatment. This carrier was prepared by self-assembly of biodegradable triblock copolymer PEG-PCL-PEG coated on oleate-modified magnetic nanoparticles. The amphiphilic triblock copolymer was synthesized via reaction between the aldehyde group from the hydrophilic component with the amine group of the hydrophobic component. The resulting Schiff base linkage was sensitive to pH. The structure of nanocarrier was characterized by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR). Morphology and size of the magnetic...