Sharif Digital Repository

Silica gel-confined ionic liquid (IL) is a class of heterogeneous catalysts with broad catalytic applications. Leaching of the IL from the surface of the support is the major drawback of these catalysts, which reduce the catalyst efficiency during the chemical reactions. To investigate the effect of the hydrogen bonding on the leaching phenomena, the interaction between the 1-ethyl-3-methylimidazolium-based IL with various anions (Cl-, Br-, HSO4 -, NO3 -, BF 4 -, and PF6 -) and the surface of the silica gel were studied using density functional theory. Hence, a hydroxylated cage-like cluster of silica gel, Si4O6(OH), was selected to mimic the surface. The values of ÎEinteraction show that... 

A new and efficient synthesis of pyrimido[4,5-d]pyrimidine-2,4-dione derivatives through the reaction of 6-aminouracils and N,N′-bis(arylmethylidene) arylmethane in the presence of molecular iodine as a readily available and feasible catalyst  

Functionally-graded NiO-8. mol % YSZ composite films were prepared by a controlled voltage-decay electophoretic deposition (EPD) process. The films consisted of three layers with varying NiO concentrations and porosities. Effects of different parameters including the type of the organic media, solid concentration, NiO:YSZ ratio, and iodine on the stability of EPD suspensions and deposition kinetics were studied. A stable NiO-YSZ suspension was attained in isopropanol with NiO-YSZ ratio of 60:40 and iodine concentration of 0.5. mM. The composite film contained varying NiO concentration from 46. wt.% near the substrate to 32. wt.% close to the electrolyte with 42. wt% NiO in the intermediate... 

Gold nanorods (GNRs) can be used in various biomedical applications; however, very little is known about their in vivo tissue distribution by radiolabeling. Here, we have developed a rapid and simple method with high yield and without disturbing their optical properties for radiolabeling of gold rods with iodine-131 in order to track in vivo tissue uptake of GNRs after systemic administration by biodistribution analysis and γ-imaging. Following intravenous injection into rat, PEGylated GNRs have much longer blood circulation times. We have developed a rapid and simple method for radiolabeling of gold rods with iodine-131 in order to track in vivo tissue uptake of gold nanorods after systemic... 

Two types of gold ores were subjected to iodide/iodine leaching at room temperature. The effects of three factors, including ore type (a carbonaceous and an oxide gold ores), iodide/iodine concentration, and the presence of oxygen in solution on gold leaching performance were investigated. The carbonaceous ore showed only 20% gold extraction into the solution; since gold-iodide complexes would readily adsorb on organic matter. In contrast, gold extraction from the oxide ore in a solution containing 20 g/L iodide and 4 g/L iodine reached 77% in 6 h and 89% in 24 h. With iodate as the oxidant, no gold could be leached in 48 hours. When the iodate was partially converted to iodine by adding HCl... 

Platinum extraction from spent reforming catalysts in iodine solutions under atmospheric pressure and at temperatures up to 95°C was previously investigated in our group. In this system, platinum is oxidized from the spent catalyst with tri-iodide. In some of the experiments, it was observed that platinum extraction peaked and then decreased. This indicates that a precipitation reaction slowly occurs that removes the dissolved Pt ions from the solution. Power-law rate equation for the Pt extraction to PtI6 2- and the precipitation of the dissolved platinum to PtI 4(s) was implemented to model the experimental Pt extraction data. The activation energies for the platinum dissolution reaction... 

The current study is aimed at comparison of adsorption behaviors of silica-supported Cu nanoparticles (Si-N-Cu) and micrometric copper powder (Mi-Cu) for uptake of iodine vapor. The Si-N-Cu was synthesized by the decomposition of aqueous Cu(NO3)2 solution at supercritical condition, followed by reduction of the sample by H 2-N2 mixture. The Si-N-Cu sample with 29.4 nm Cu particles adsorbed 95% of I2 at partial pressure 10-5 bar in 1 h, while the 1 μm Mi-Cu adsorbed 51% of iodine in 6 h, indicating higher yield and faster kinetics of the nanometric sample. Theoretical analysis revealed the existence of a strong thermodynamic size effect in the Cu-I2 reaction system, so that molar |ΔG| for 2... 

Various methods, such as those developed by the Medical Internal Radiation Dosimetry (MIRD) Committee of the Society of Nuclear Medicine or employing dose point kernels, have been applied to the radiation dosimetry of 131I radionuclide therapy. However, studies have not shown a strong relationship between tumour absorbed dose and its overall therapeutic response, probably due in part to inaccuracies in activity and dose estimation. In the current study, the GATE Monte Carlo computer code was used to facilitate voxel-level radiation dosimetry for organ activities measured in an . 131I-treated thyroid cancer patient. This approach allows incorporation of the size, shape and composition of... 

Two types of gold ores were subjected to iodide/iodine leaching at room temperature. The effects of three factors, including ore type (a carbonaceous and an oxide gold ores), iodide/iodine concentration, and the presence of oxygen in solution on gold leaching performance were investigated. The carbonaceous ore showed only 20% gold extraction, since gold-iodide complexes readily adsorb on organic matter. In contrast, gold extraction from the oxide ore in a solution containing 20 g/L iodide and 4 g/L iodine reached 77% in 6 h and 89% in 24 h. With iodate as the oxidant, no gold could be leached in 48 h. When the iodate was partially converted to iodine by adding HCl to the solution, gold... 

Vertical copper oxide nanoflakes were synthesized on a Cu foil through oxidation in alkaline conditions. X-ray photoelectron spectroscopy showed that after exposing the nanoflakes to an Escherichia coli bacterial suspension, the outermost surface of the nanoflakes was chemically reduced through the glycolysis process of the bacteria. Current-voltage (I-V) characteristics of the nanoflakes (measured perpendicular to surface of the Cu foil by using conductive atomic force microscopy) indicated that electrical resistivity of the nanoflakes increased about one order of magnitude after exposure to the bacterial suspension. The nanoflakes reduced by the bacterial suspension could also be... 

In the present work the production of biodiesel using bitter almond oil (BAO) in a potassium hydroxide catalyzed transesterification reaction was investigated. The BAO was obtained from resources available in Iran and its physical and chemical properties including iodine value, acid value, density, kinematic viscosity, fatty acid composition and mean molecular weight were specified. The low acid value of BAO (0.24. mg. KOH/g) indicated that the pretreatment of raw oil with acid was not required. The fatty acid content analysis confirmed that the contribution of unsaturated fatty acids in the BAO is high (84.7. wt.%). Effect of different parameters including methanol to oil molar ratio (3-11.... 

Electrophoretic technique was used to deposit micro- and nano-sized aluminum nitride coatings on stainless steel surfaces by using a well-dispersed stable suspension produced by addition of AlN powder plus a small amount of iodine to ethanol. Parabolic regime governed the deposition. Electrophoretic deposition for 240 s at 100 V resulted in formation of a uniformly dense film on the top, but a porous inhomogeneous layer at the bottom. This was attributed to fast deposition of coarse particles and/or agglomerates at large electric fields. After drying, micro-sized particles led to a uniform crack-free interface while nano-particles resulted in fragmented non-cohesive layers. Weight loss... 

Watermelon seed oil characteristics were evaluated to determine whether this oil could be exploited as an edible oil. Hexane extraction of watermelon seeds produced yields of 50% (w/w) oil. The refractive index, saponification and iodine value were 1.4712 (at 25 °C), 200 mg KOH/g and 156 g I/100 g, respectively. The acid and peroxide values were 2.4 mg KOH/g and 3.24 mequiv/kg, respectively. The induction time of the oil was also 5.14 h at 110 °C, which was measured for the first time. Total unsaturation contents of the oil was 81.6%, with linoleic acid (18:2) being the dominant fatty acid (68.3%). Considering that the watermelon seed oil was highly unsaturated, the relatively high induction... 

Effective masses are calculated for a large variety of perovskites of the form ABX3 differing in chemical composition (A= Na, Li, Cs; B = Pb, Sn; X= Cl, Br, I) and crystal structure. In addition, the effects of some defects and dopants are assessed. We show that the effective masses are highly correlated with the energies of the valence-band maximum, conduction-band minimum, and band gap. Using the k·p theory for the bottom of the conduction band and a tight-binding model for the top of the valence band, this trend can be rationalized in terms of the orbital overlap between halide and metal (B cation). Most of the compounds studied in this work are good charge-carrier transporters, where the... 

The compatibility of atomic layer deposition directly onto the mixed halide perovskite formamidinium lead iodide:methylammonium lead bromide (CH(NH2)2, CH3NH3)Pb(I,Br)3 (FAPbI3:MAPbBr3) perovskite films is investigated by exposing the perovskite films to the full or partial atomic layer deposition processes for the electron selective layer candidates ZnO and SnOx. Exposing the samples to the heat, the vacuum, and even the counter reactant of H2O of the atomic layer deposition processes does not appear to alter the perovskite films in terms of crystallinity, but the choice of metal precursor is found to be critical. The Zn precursor Zn(C2H5)2 either by itself or in combination with H2O during... 

Effective masses are calculated for a large variety of perovskites of the form ABX3 differing in chemical composition (A= Na, Li, Cs; B = Pb, Sn; X= Cl, Br, I) and crystal structure. In addition, the effects of some defects and dopants are assessed. We show that the effective masses are highly correlated with the energies of the valence-band maximum, conduction-band minimum, and band gap. Using the k·p theory for the bottom of the conduction band and a tight-binding model for the top of the valence band, this trend can be rationalized in terms of the orbital overlap between halide and metal (B cation). Most of the compounds studied in this work are good charge-carrier transporters, where the...