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

In the current paper, finite element method is employed for numerical simulations and the study of influential parameters on elastic modulus of polymer-matrix nano-composites. Effects of different key parameters including particle elastic modulus, interphase elastic modulus, matrix elastic modulus, interphase thickness and particle volume fraction on total elastic modulus of nano-composite materials are observed in order to shed some light on experimental parameters that are difficult to measure. To this end, a three phase (i.e. particle, interphase and matrix) unit cell is modelled and results compare with previously introduced theoretical model. It is found that interphase parameters such as elastic modulus and thickness strongly influences the elastic properties of the nano-composite and cannot be neglected.

Nano structured materials have wide range of applications due to their interesting size-dependent chemical and physical properties compared to particles of size in the range of micrometer. Copper oxide nano materials are of interest on account of their potential uses in many technological fields. In this study CuO nanoparticles were synthesized via simple sol gel method using basic CuSO4 as wet chemically synthesized precursor and NaOH as stabilizing agent. Samples were characterized by X-ray diffraction (XRD), Infrared spectrum (IR), and Scanning electron microscope (SEM).We studied the antibacterial activity of this CuO nanoparticles against Gram-positive and Gram-negative bacterial strains. Using this method, CuO nanoparticles could be synthesized without using organic solvent, expensive raw materials and complicated equipments. Besides simplicity, the advantage of producing nanoparticles by this method is that it is easeful, flexible, fast, cost effective, and pollution free.

Metal nanoshells consists of a dielectric core surrounded by a thin noble metal shell, possess unique optical properties, which render nanoshells attractive for use in different technologies. This paper reports a facile method for growth of small gold nanoparticles on the functionalized surface of larger silica nanoparticles. Mono-dispersed silica particles and gold nanoparticles were prepared by the chemical reduction method. The size of the shell nanoseeds could be altered by repeating the stage of reducing HAuCl4 on Au/APTES/silica particles, and the time for which they react. The nanocore-shell particles prepared were studied using transmission electron microscopy (TEM), UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and PL spectrophotometer. The TEM images indicated that by growing gold nanoseeds over the silica cores a red shift in the maximum absorbance of UV-Visible spectroscopy is observed. Furthermore, a remarkable intensification happens in the PL spectra of silica@Au NPs in comparison with that of bare silica NPs. But, the existence of gold nanoseeds on the silica particles surfaces does not change the PL spectra peaks of these nanoparticles.

Synthesis, identification and thermal behavior studies of nanoparticles cobalt (II) bromide has been studied in this research. Cobalt (II) bromide was synthesized by planetary high-energy ball mill. The general formula of this compound is CoBr2.6H2O. The synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy and also Size and structure of synthesized nanoparticles were studied by analyzing X-ray diffraction and morphology of surface and structure of synthesized nanoparticles were studied by scanning electron microscopy. This compound has many applications in mineral synthesis as a catalyst. The nanoparticles of CoBr2.6H2O synthesized with smaller size of 35 nm, and its SEM images show that the morphology of particles surface is as like as layer. Also, the thermal behavior of these nanoparticles is considered by using of DTA /TGA thermal analysis.

The aim of the present study was to develop Exemestane loaded polymeric nanoparticles for improved oral bioavailability of Exemestane. Exemestane loaded nanoparticles were prepared by solvent displacement method with Eudragit RL 100 and Eudragit L 100 as polymers and Pluronic Ò F-68 as surfactant. The influence of various formulation factors (drug: polymer ratio and concentration of surfactant) on particle size, size distribution, zeta potential, encapsulation efficiency, in vitro drug release were investigated. The mean particle size of optimized formulations F5 and F13 were found to be 98.19nm and 48.16nm respectively. Zeta potential of optimized formulations F5 and F13 were found to be+22mV and -25mV respectively. Fourier Transform Infrared Spectroscopy (FT-IR) study indicated that, there was no interaction between drug and polymers. Scanning electron microscopy (SEM) study revealed spherical morphology of the developed NPs. The results of the present investigation indicate that the formulations F5 and F13 can be considered as best among various formulations with respect to particle size, entrapment efficiency and in-vitro drug release. In conclusion, this study indicates the capability of Eudragit nanoparticles in enhancing the oral bioavailability of exemestane.

The aims of the study were to investigate the effect of poly (e-caprolactone) (PCL) and nano- SiO2 within the thermoplastic starch (TPS) blends on the rate and extent of starch enzymatic hydrolysis using enzymes α-amylase and amyloglucosidase. The results of this study have revealed that blends with nano-SiO2 content at 6 wt% exhibited a significantly reduced rate and extent of starch hydrolysis. The results suggest that this may have been attributed to interactions between starch and nano- SiO2 that further prevented enzymatic attack on the remaining starch phases within the blend. The total solids that remained after 6000 min were 52 wt. % (TPS: PCL); 59 wt.% (TPS: PCL: 2% nano-SiO2); 64 wt.% (TPS: PCL: 4% nano-SiO2); 67 wt.% (TPS: PCL: 6% nano-SiO2). The rate of glucose production from each nanocomposite substrates was most rapid for the substrate without nano- SiO2 and decreased with the addition of nano- SiO2, for TPS: PCL blend (374 mg/ml.h), 246 mg/ml.h (TPS: PCL: 2% nano- SiO2), 217 mg/ml.h (TPS: PCL: 4% nano- SiO2) and 199 mg/ml.h for (TPS: PCL: 6% nano- SiO2). Enzymatic degradation behaviour of TPS: PCL: nano- SiO2 was based on the determinations of Water resistance, Weight loss and the Reducing sugars.

Cadmium Oxide (CdO) nanoparticles were prepared by precipitation method using Cadmium acetate and ammonia solution. Presence of chemical species, were verified by Fourier Transform Infra Red (FTIR) Spectrum. From X-Ray Diffraction (XRD) spectrum the particle size, d-spacing value and structure of the nanoparticle were analysed. Size of the nanoparticles and the elemental composition were detected by using Scanning Electron Microscope (SEM) with Energy Dispersive X-Ray Analysis (EDAX). The optical band gap of CdO nanoparticles has been determined by using UltraViolet-Visible (UV-Vis) absorption spectroscopy. The antimicrobial activities of different concentration of the CdO nanoparticles were tested by treating E.coli cultures with CdO nanoparticles. Cadmium Oxide nanoparticles show effective antimicrobial activity. Different organisms were used to observe the zone of inhibition of CdO nanoparticles.

Automotive and aerospace industries are required to light materials which have high properties. This causes to reduce production cost and fuel consumption. One of these advanced materials that have been attracted at these decades is particulate metal matrix nanocomposites. These materials have a combination of ductile matrix alloy properties and ceramic reinforcement nanoparticles. Powder metallurgy is one of the significant methods to fabricate this kind of materials. In this research, aluminum alloy matrix nanocomposites reinforced with 1.5, 2.5, 3.5, 5, and 10 Vol. % TiB2 nanoparticles were fabricated via powder metallurgy method. Fabrication was performed at two different sintering temperatures, viz.650 and 680oC. Optimum amount of reinforcement and sintering temperature was determined by evaluating density and microstructural studies of nanocomposites. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis illustrated that distribution of nano TiB2 particles in aluminum matrix is suitable. Also, density results showed that with increasing the TiB2 volume percent, density of composites increases.

In study, spherical Silver nanoparticles (SNPs) were synthesized by chemical reduction method from a metal precursor silver nitrate in presence of an anionic surfactant and strong reducing agent. In this experimental work, SNPs are synthesized in presence of different concentration of stabilizing agent and effect of stabilizing agent on size distribution of SNPs have been observed. Further antibacterial activities of the SNPs prepared under different concentration of sodium lauryl sulphate (SDS) carried out on gram negative and gram positive bacteria showed that as concentration of sodium lauryl sulphate increases antibacterial activity decreases.

Biosynthesis of silver nanoparticles with small size and biostability is very important and used in various biomedical applications. In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Olea europaea (Oe) and its antibacterial activity. UV–visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35 min of reaction time. The synthesized Ag-NPs were characterized by a peak at 449 nm in the UV–visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 34 nm size. The XRD peaks at 38o, 44o, 64o and 77o can be indexed to the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) Bragg’s reflections of cubic structure of metallic silver, respectively. The results confirmed that the (Oe) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods.

In this paper, we used tetranuclear copper (II) Schiff base complexes, [Cu4 (m-sal2hn) (m-N3) 2 (N3) 2] (1) and [Cu4 (m-salophen) (m1, 1-N3) 2 (N3) 2] (2), as new precursor in solid-state thermal decomposition for the synthesis of CuO nanoparticles. The crystallinity, purity and morphology of the CuO nanoparticles were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM).