سال:1393 | دوره: | شماره: |تعداد مقالات:11

In the present study, Fe3O4 super paramagnetic nanoparticles were synthesized via co-precipitation of Fe3+ and Fe2+ chloride salts in the presence of ammonia Solution. The product was characterized by Fourier Transform Infrared spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), and zeta-potential particle size distributing methods. The synthetic procedure of nano iron oxides were optimized using modern statistical optimization methods. A major bottleneck of common optimization protocols is the variation of just one factor at each trial. In modern optimization protocols (experimental design) a combination of factor levels is considered. In the present study, response surface method (RSM) was applied to optimize the synthetic approach towards Fe3O4 nanoparticles. Results indicated the importance of acidity and ferric ion amount in achieving desired Fe3O4 nanoparticles.

In the present study, an attempt was made to develop galactosylated albumin nanoparticles of Cimetidine for treatment of Acetaminophen induced hepatotoxicity. By developing the galactosylated nanoparticulated delivery of Cimetidine the required action of drug at the target site i.e at liver can be provided. The advantage of targeting helps to reduce the systemic side effects which may be occur due to the distribution of the drug to the other organs and thus helps in maintain the required concentration of drug at the desired site. The use of cimetidine to treat Acetaminophen induced hepatotoxicity was based on the observation that it would lead to the competitive inhibition of the enzyme CYP 450 2E1 and reduce the acetaminophen metabolism to N-acetyl-p-benzoquinoneimine (NAPQI), a highly reactive, electrophilic molecule. Thus, it might be useful in treatment of Acetaminophen induced hepatotoxicity. The galactosylated albumin nanoparticles were prepared for the selective delivery of an, Cimetidine to the asialoglycoprotein receptor (ASGP-R) which is particularly presents on mammilla in hepatocytes. The albumin nanoparticles (NPs) were prepared by using desolvation method and efficiently conjugated with galactose. Various parameters such as particle size, % entrapment efficiency and drug loading efficiency, percentage yield, in vitro drug release, were determined. The size of nanoparticles (both plain and coated NPs) was found to be in range of 200-250 nm, and maximum drug payload was found to be 19.08%±1.10. The maximum drug content was found to be 30.80%±0.3 and 27.09%±0.5 respectively in plain and galactose coated nanoparticles while the maximum entrapment efficiency was found to be 90.68%±0.5 and 91.75%±0.59 in plain and coated nanoparticles. It was also found that coating of nanoparticles increases the size of nanoparticles.

Polyacrylonitril (PAN) -supported chitosan (CS) nanocomposite membranes were prepared by cross-linking the CS with 3-aminopropyl-triethoxysilane (APTEOS) via sol-gel method. Pervaporative performances of the CS-SiO2/PAN membrane for dehydration of aqueous alcohol solutions were investigated. From SEM cross-sectional images of the membrane, the spongy pores and the finger-like pores were found in cortex and intermediate layer. The PAN microporous substrate and the top layer were about 100 and 7.4 mm thick, respectively. The separation factor and permeation flux of the synthesized CS/PAN and CS-SiO2/PAN membranes indicated that introducing 5% of nanosilica to skin layer of the composite membrane improved its pervaporative properties. At 30oC, a separation factor of 20.03 and 34.25 were achieved for CS/PAN and CS-SiO2/PAN membranes, respectively.

We report the synthesized and preparation of graphene oxide (GO) nanocomposite functionalized with polyvinyl alcohol (PVA) with different concentration of graphene oxide 0, 1, 1.5, 2, 2.5, 3, 3.5 and 4% weight. This synthesized confirmed by FT-IR. The electrical conductivity of the all nanocomposite was measured at 25oC for all samples and the resulted showed electrical conductivity was increased with increasing % weight graphene in nanocomposite.

In Hard Disk Drives (HDD), it is necessary to decrease the Flying Height (FH) between the head and the disk (currently, FH is around 3-5 nm) so as to increase recording densities. Retaining the solid lubricant has become a difficult proposition owing to intermittent contact between the surfaces. ZTMD and Z are used as solid lubricant to lubricate these interfaces. In this paper, the behavior of the binary mixture lubricant such as ZTMD & Z is modeled and analyzed using Molecular Dynamics (MD) simulation with the help of GROMACS software. It can be observed from simulation studies that ZTMD has poor replenishment performance although it possesses good retention properties. Addition of Z molecules improves replenishment performance of whole system. When ZTMD molecules alone are modeled, final structure attains stable state only at -4800 kJmol-1. After the addition of Z molecules, final structure (ZTMD+Z) attains more stable state at -6950 kJ mol-1. When compared to ZTMD, binary mixture lubricants (ZTMD+Z) are considered as more stable and for use in HDDs for their efficient operation.

The continuous development of global economy with decreasing in available hydrocarbon sources and increasing discovery and extraction costs due to decrease in-situ oil and gas reservoir, displays the necessity of using new techniques for the improve rate of penetration and productivity in well. Nanotechnology has already contributed significantly to technological advances in the energy industries. Nanotechnology has the potential to introduce revolutionary change in drilling industry. Nanotechnology produces nanomaterials with many attractive properties, which can play an important role in intensifying mud cake quality, reducing friction, eliminating differential pipe sticking, maintaining borehole stability, protecting reservoir, and enhancing oil and gas recovery. Nano fluids can be designed by adding nano-sized particles in low volumetric fractions to a fluid. The nano particles modify the fluid properties, and suspensions of nano-sized particles can provide numerous advantages.This paper presents an extensive literature review of assessing the applications of nanomaterials in drilling and drilling fluids, and evaluates the potential technical benefits that these nanomaterials might provide to petroleum development and production.

The electronic conductance at zero temperature through a quantum wire with side-connected asymmetric quantum ring (as a scatter system) is theoretically studied using the non-interacting Hamiltonian Anderson tunneling method. In this paper we concentrate on the configuration of the quantum dot rings. We show that the asymmetric structure of QD-scatter system strongly influences the amplitude and spectrum of electron transport characteristics through a quantum wire. We find that the unbalanced number of quantum dots in two rings rather increases the anti-resonant in quantum wire conductance than balances the number of quantum dots rings. Also changing the distance between quantum dot rings influences the amplitude of resonant peaks in the QW conductance spectrum. The proposed asymmetric quantum ring scatter system idea in this paper opens a new insight on the designing of nano structure quantum wire for a given electrical conductance.

ZnO thin films with preferred orientation along the (002) plane were prepared onto the glass substrates by the sol-gel spin coating method for different post- annealing temperatures. The XRD study confirms that the thin films grown by this method have good crystalline hexagonal wurtzite structure. The optical band gap of the samples was determined from UV-visible spectra. It is found that the size of the ZnO grains increase and the optical band gap of the films decrease as the annealing temperature increases from 350oC to 550oC. The transmittance of the film in the visible range was about 75%, 85% and 65% for 350oC, 450oC and 550oC annealed samples respectively. SEM images of the films show worm shaped structures at 350°C and distinct grains in films annealed above 350oC. Photoluminescence spectral study reveals that all the samples exhibit violet luminescence. The resistivity of the ZnO films found to reduce drastically from mega ohm to ohm range as a result of further vacuum annealing treatment of samples. The variation of electrical resistivity with respect to intensity of UV illumination over the samples has been reported.

In this paper, a modified sol-gel method using peroxotitanic acid sol (PTA) was applied for the preparation of TiO2 nanostructured thin films on glass plates. The peroxotitanic acid sol was synthesized using titanium isopropoxide, isopropylalchol, H2O and hydrogen peroxide. TiO2 films were then calcined at 500oC and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results showed that increasing the number of coated layers would lead to the formation of anatase phase at high level. Addition of Polyethylene Glycol (PEG) on the PTA sol could cause uniform coating without any cracks. The photocatalytic performance of the obtained films was investigated by the photodegradation measurements of Reactive Red 222 (RR222) in a batch reactor. For further investigations the effect of some parameters such as initial RR222 concentration, pH value, hydrogen peroxide addition and temperature on the photocatalytic performance of TiO2 thin films was studies as the important factors. Kinetic study results of this reaction represented that it obeys of was pseudo-first-order model. The degradation of RR22 was enhanced by the addition of optimum amount of hydrogen peroxide. This is due to the increasing amount of the radical hydroxyls.

ZnO nanorod was prepared by microwave assisted method. The crystal structure of the nano powders were confirmed by X-Ray diffraction analysis and the mean particle size was estimated by the Scherrer, s formula. The surface morphology of the nano particles were analyzed by using SEM. The absorption spectrum of the material in the UV-Vis range was recorded. The energy band gap of the material was obtained from the absorption wavelength of the UV-Vis spectrum. The short emission wavelength of the material was confirmed by using Photoluminescence studies. The effects of frequency on the dielectric behaviour and ac electrical conductivity have been studied.

Two-component reaction of 2-aminobenzophenones with acetylenic esters in the presence of g-Al2O3 and Cu/ZnO as suitable heterogeneous catalysts has been studied. Nano γ-Al2O3 and Cu/ZnO showed high activities when used as surface catalysts for the synthesis of quinoline derivatives. After completion of the reaction, the catalyst was recovered and reused several times under the same reaction conditions.