Sharif Digital Repository

The influences of hydroxyl functional group (-OH) on the thermodynamic and structural properties of ionic liquids (ILs) composed of 1-(2-Hydroxyethyl)-3-methyl imidazolium ([C2OHmim](+)) cation and the six different conventional anions, including [Cl](-), [NO3](-), [BF4](-), [PF6](-), [TfO](-), and [Tf2N](-) have been extensively investigated using classical molecular dynamics (MD) simulations combined with ab initio calculations over a wide range of temperature (298-550 K). The volumetric thermodynamic properties, enthalpy of vaporization, cohesive energy density, Hildebrand solubility parameter, and heat capacity at constant pressure were estimated at desired temperature. The simulated... 

The microscopic features of binary solvent systems formed by molecular solvents (methanol, ethanol, 2-methylpropan-2-ol, water, pyridine, acetonitrile, 1-propanol, 2-propanol, dimethylformamide) and the ionic liquid ([bmim]BF4) as cosolvent were used to select mixed solvents with particular characteristics. Molecular-microscopic solvent parameters corresponding to these binary mixtures were utilised to study the kinetics of the nucleophilic substitution reaction between 2-chloro-3,5-dinitropyridine and aniline to investigate and compare the effects of the solvents on a model chemical reaction. For these mixtures, the solvation behaviour is dominated by both the dipolarity/ polarisability and... 

Rate constants, k A, for the aromatic nucleophilic substitution reaction of 2-chloro-3,5-dinitropyridine with aniline were determined in different compositions of 2-propanol mixed with hexane, benzene, and 2-methylpropan-2-ol and 1-ethyl-3-methylimidazolium ethylsulfate ([Emim][EtSO4]) with dimethyl sulfoxide at 25°C. The obtained rate constants of the reaction in pure solvents are in the following order: 2-methylpropan-2-ol > dimethyl sulfoxide > 2-propanol > hexane > benzene > [Emim][EtSO4]. Molecularmicroscopic solvent parameters corresponding to the selected binary mixtures were utilized to study the kinetics of a nucleophilic substitution reaction in order to investigate and compare the... 

Mordenite (MOR) nanocrystals were synthesized using the hydrothermal method. Sol–gel and deposition methods were utilized to modify the zeolite surface with TiO2 and then AgBr or AgCl particles. Photocatalysts were characterized by using X-ray diffraction, Brunauer–Emmett–Teller (BET), and scanning electron microscopy techniques. Activity was evaluated by photodegradation of Acid Blue 92 as an azo dye. The effect of silver halide deposition on the photocatalytic behavior of the prepared nanocomposites was studied under both ultraviolet (UV) and visible light, and the results were compared. The results showed that AgCl/TiO2/MOR was more active under UV, while with visible source,... 

Photocatalytic reduction of p-nitrochlorobenzene was studied over aluminosilicate-based AgBr and AgBr-TiO2 photocatalysts which were prepared and characterized. The photoreaction was performed in the presence of LiBH4, which is a strong reducing agent, in the solution medium. A new mechanism is proposed for reduction of p-nitrochlorobenzene under photocatalytic conditions. The effect of pH, illumination source, LiBH4 concentration, temperature, catalyst dosage, and alcoholic scavengers was also studied. The results showed that the best efficiency was obtained over Ag/AgBr/TiO2/aluminosilicates at natural pH under UV light. We observed that the reaction yield was affected by changing the... 

Selective oxidations of alkenes were investigated using molecular oxygen in aqueous solution under mild conditions. Colloidal gold nanoparticles are particularly versatile catalysts for oxidation reaction with exceptionally high efficiency and significant selectivity. Gold nanorods (Au NRs) exhibited a slightly enhanced activity compare to gold nanospheres  

Structural and intermolecular interactions of solvatochromic probes 4-nitroaniline, 4-nitroanisole, and Reichardt’s dye were investigated in the binary mixtures of 2-hydroxy ethylammonium formate as an ionic liquid with N,N-dimethyl formamide, dimethyl amine, and dimethyl sulfoxide. Solvatochromic parameters (ETN, normalized polarity parameter; π*, dipolarity/polarizability; β, hydrogen-bond acceptor basicity; α, hydrogen -bond donor acidity) were determined in ionic liquid mixtures at 25 °C using UV−vis spectroscopy. ETN parameters obtained from absorbance of Reichardt’s dye within various mixtures of ionic liquid were observed to be higher than predicted values from ideal additive... 

Solute-solvent and solvent-solvent interactions were investigated for binary mixtures of an ionic liquid (IL) 2-hydroxy ethylammonium formate as with methanol, ethylene glycol and glycerol. The physicochemical properties of the solvent mixtures at 25 °C, over the whole range of mole fractions, were determined using solvatochromic probes. High normal polarity ( ENT ) in the alcohol-rich region confirms solute-solvent interactions in this medium. Dipolarity/polarizability (π ∗) show a different trend to ENT with a positive deviation from ideal behavior in IL-glycerol mixtures. However, these deviations for other solvent mixtures are insignificant. Contrary to what is observed for ENT and π ∗,... 

Structural and molecular-microscopic properties of the solvatochromic probes 4-nitroaniline, 4-nitroanisole, and Reichardt’s dye were investigated in binary mixtures of ethylammonium propionate with methanol, ethanol, 1-propanol and 2-propanol. Solvatochromic parameters (α, hydrogen-bond donor acidity; β, hydrogen-bond acceptor basicity; π*, dipolarity/polarizability; ENT , normalized polarity parameter) in different binary mixtures of ionic liquid with molecular solvents were determined with UV–Vis spectroscopy. The ENT parameters show nearly ideal trends in all solvent mixtures, but the other parameters show different behavior in the mixtures. The π* parameters show a negative deviation... 

The mechanism of selectivity in ion channels is still an open question in biology for more than half a century. Here, we suggest that quantum interference can be a solution to explain the selectivity mechanism in ion channels since interference happens between similar ions through the same size of ion channels. In this paper, we simulate two neighboring ion channels on a cell membrane with the famous double-slit experiment in physics to investigate whether there is any possibility of matter-wave interference of ions via movement through ion channels. Our obtained decoherence timescales indicate that the quantum states of ions can only survive for short times, i.e. ∼100 picoseconds in each... 

Time-cost trade-off problems (TCT) are well-known in project management contents. This approach normally applied for scheduling of a project especially where the project should be completed under pre-determined deadline. This paper aims to extend time-cost trade-off (TCT) problems in order to provide a well-organized mechanism for both scheduling and rescheduling processes of a project. The proposed mechanism includes project scheduling which concerns with the TCT problem, monitoring of project performance during execution phase using earned value management (EVM), and also predicting project future performance through statistical modeling. Once the predicted values of project performance... 

This work aims to compare results of dissipating and pure dephasing single-qubit probes in characterizing the cutoff frequency of a harmonic reservoir Ohmic spectral density. In particular, we proved that a dissipating single-qubit improves the estimation precision of the cutoff frequency estimator. The information backflow and outflow of the dissipating and the dephasing single-qubit are compared. The relation between the quantum Fisher information and the information outflow and backflow of the probe is obtained. The results show that difference between the values of information outflow and backflow of a dissipating single-qubit is larger than a dephasing single-qubit. So, a single-qubit... 

Ant colony optimization (ACO) is a well-known metaheuristic in which a colony of artificial ants cooperate in exploring good solutions to a combinatorial optimization problem. In this paper, an ACO algorithm is presented for the graph coloring problem. This ACO algorithm conforms to max-min ant system structure and exploits a local search heuristic to improve its performance. Experimental results on DIMACS test instances show improvements over existing ACO algorithms of the graph coloring problem  

The behaviour of solvatochromic absorbance probes (4-nitroaniline, 4-nitroanisole, and Reichardt's dye) within binary mixtures of polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether (Triton X-100 or TX-100)/organic solvents (2-propanol, hexanol, butyl acetate, THF, toluene, and p-xylene) was extensively explored by using solvatochromism and the quantum theory of atoms in molecules (QTAIM). To be more precise, the polarity parameters, ET N, and Kamlet-Taft parameters, such as the hydrogen bond donor ability (HBD) (α), hydrogen bond acceptor ability (HBA) (β), and dipolarity/polarizability (π∗), have been investigated in selected mixtures at 298 K. All binary mixtures exhibit complex... 

The key element of a spoken dialogue system is a spoken language understanding (SLU) unit. Hidden Vector State (HVS) is one of the most popular statistical approaches employed to implement the SLU unit. This paper presents a two-step approach for Persian language understanding. First, a goal detector is used to identify the main goal of the input utterance. Second, after restricting the search space for semantic tagging, an extended hidden vector state (EHVS) parser is used to extract the remaining semantics in each subspace. This will mainly improve the performance of semantic tagger, while reducing the model complexity and training time. Moreover, the need for large amount of data will be... 

XFe2O4 magnetic nanoparticles (X = Mn, Fe, Co, Ni, and Zn) were prepared by using two methods: coprecipitation and hydrothermal. The synthesized nanoparticles were compared according to the separation in an external magnetic field and finally, the hydrothermal method was specified as a better synthesis method. The magnetic nanoparticles were characterized by physico-chemical analysis methods such as Vibrating Sample Magnetometer (VSM), X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), nitrogen adsorption-adsorption isotherm and Transmission Electron Microscopy (TEM). Magnetic properties of synthesized nanoparticles were studied by ab-initio theoretical methods to... 

In this paper, we propose an optimized parameter selection procedure for rainbow table Time Memory Trade-Off (TMTO) attack with sequential online search. Unlike previous works that mainly deal with minimizing required memory in the rainbow table TMTO attack we simultaneously focus on the required memory and online search time. Our parameter selection technique is optimized regarding the minimization of the required memory subject to a certain success probability and a maximum online search time. Obtained results are two compact mathematical expressions for determining rainbow table TMTO attack parameters, number and length of chains. The application of our optimized parameter selection...