سال:1392 | دوره: | شماره: |تعداد مقالات:8

Red-emitting Eu3+-doped indium gallium zinc oxide (IGZO) transparent thin films were fabricated using sol–gel method under UV (254-nm irradiation) in nitrogen atmosphere (inside the glove box) and thermally annealed at 500oC for 1 h. Structure, morphology, composition, and optical properties of the materials were examined using X-ray diffraction analysis, scanning electron microscope, X-ray photoelectron spectroscopy, and photoluminescence, respectively.

Size reduction of the catalyst increases the surface area, and hence, the catalytic activity is also increased. The decrease in temperature of decomposition of ammonium perchlorate in the presence of nano-copper oxide and nano-ferric oxide is investigated within the scope of this study. Different mixes of ammonium perchlorate with nano-ferric oxide and nano-copper oxide were prepared. Differential scanning calorimetry test results show that addition of nanometer-sized ferric oxide and copper oxide leads to a significant decrease in higher decomposition temperature of ammonium perchlorate. The most significant decrease in the decomposition temperature was observed in the presence of 3% of nano-copper oxide.

Nanostructured metal-organic hybrid materials composed of nickel (II), copper (II), and zinc (II) metal ions and p-phenylenediamine (PPD) as the organic ligand were synthesized in aqueous medium at room temperature. The synthesized compounds were characterized by elemental analyses, powder X-ray diffraction (PXRD) spectra, Fourier transform infrared spectra, nuclear magnetic resonance (1H NMR) spectra, electronic spectra, scanning electron microscopy, N2 adsorption-desorption isotherm, and dynamic light scattering studies. N2 adsorption-desorption isotherm of copper (II) -PPD compound confirmed that it has mesoporous structure as it exhibits type-IV reversible isotherm with H1 hysterisis. Steep adsorption indicated that the mesopores possessing it are of uniform order. Barrett-Joyner- Halenda model showed an average pore diameter of 5.2 nm. The PXRD patterns of all the three compounds are identical and showed well-defined and highly intense diffraction peaks, thereby suggesting their nature as crystalline. The broadness of the diffraction peaks indicated that the particles are of nanometer dimensions.

Extracting pure fullerene (C60) from fullerene soot was accomplished in two steps. In the first step, extraction was carried out using a Soxhlet extractor. Different solvents, such as toluene, were used in this method. In this process, light and heavy fullerenes were separated from impurities such as soot and other compounds. The applied fullerene soot was produced using an electric arc method, and the obtained purity was close to 7%. In the next step, fullerene C60 can be separated from other fullerenes (particularly C70) by column chromatography. The stationary phase in the chromatography column contained a mixture of activated carbon, silica gel, and celite, and in order to achieve a high efficiency for separation, the column was filled with a combination of these compounds. Organic solvents such as chlorobenzene and 1, 2-dichlorobenzene were used as the mobile phase. Several experiments were designed and conducted to obtain optimal conditions, and consequently, the fullerene C60 was purified with proper efficiency. In this method, parameters including efficiency, low cost, and simplicity are of great importance in the aim of obtaining an optimized method. As a result, a suitable method with low cost and high efficiency was used in this research.

The activity of two surface-enhanced Raman scattering (SERS) substrates was investigated using neodymium oxide (Nd2O3) molecules. Colloidal silver solution, containing nano-sized silver particles and silver-coated filter papers were used as the SERS substrates. In order to characterize the substrates, ultraviolet–visible spectroscopy, dynamic light scattering, and scanning electron microscopy were used. Subsequently, gain enhancement factors were calculated from the measured spectra to monitor the change in effectiveness of the SERS substrates under prolonged storage time. Experimental results show that for enhancing the Raman signal, the activity of two fabricated substrates is very effective.

Visible-light-activated Cr2O3/SnO2 nanocomposite photocatalyst was prepared by coprecipitation method and characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption-desorption measurement, and UV–vis diffuse reflectance spectroscopy. The results show that phase composition, crystallite size, Brunauer-Emmett-Teller surface area, and optical absorption of samples varied significantly with the heat treatment temperatures. The Cr2O3/SnO2 photocatalyst (the molar ratio Cr to Sn is 1: 2) calcined at 400oC for 2 h exhibited maximum photocatalytic activity because it has a smaller particle size of 10.05 nm and a higher surface area of 38.75 m2/g. Under visible-light (l>400 nm) irradiation, the degradation rate of Rhodamine B reached 98.0% in 60 min, which is about 3.5 times higher than that of the standard P25 photocatalyst.

In the present study, an attempt has been made to impart antimicrobial finishing to the cellulose fabric using nano silver solution at various concentrations (5, 10, 15, 20 and 25 ml) and an eco-friendly crosslinking agent by the exhaustion technique. Curing conditions were varied, keeping curing temperatures at 110oC and 100oC and curing times to 1 and 2 min. To assess the quality of the finished fabric, various properties such as washing fastness and zone of inhibition were studied. The zones of inhibition have been studied using Escherichia coli bacteria to determine antimicrobial activity of the fabric; the surface characteristics of these fabrics have been studied by scanning electron microscopy (SEM).In the case of the treated commercial cotton fabric product, the zones of inhibition are at a minimum of 14 mm and a maximum of 18 mm for Gram-negative bacteria. SEM study and antibacterial tests of the silver-finished fabrics indicated that, generally, silver nanoparticles were well dispersed on the fabric surface. Antibacterial test was used to estimate the biological activity of the treated fabrics, and Gram-negative bacteria (Escherichia coli) were used for this purpose. The washing fastness of finished textiles was investigated in terms of ISO 105 CO3-1982 standard. The results obtained proved the good and long-lasting bacteriostatic efficacy of silver nanoparticles applied during the finishing of cotton and viscose.

The synthesis of metal nanoparticles using algae has been unexplored, but it is a more biocompatible method than the other biological methods. Metal nanoparticle synthesis using algae extract shows rapid and non-toxic process which resulted to nano sizes having the greatest potential for biomedical applications. In this investigation, we studied the green synthesis of gold nanoparticles using the algae extract of Turbinaria conoides. Green synthesis of gold nanoparticles was preliminarily confirmed by color changing from yellow to dark pink in the reaction mixture, and the broad surface plasmon resonance band was centered at 520 to 525 nm which indicates polydispersed nanoparticles. Transmission electron microscopy and selected-area electron diffraction analysis show the morphology and crystalline structure of synthesized gold nanoparticles with the size range of 6 to 10 nm. The four strong diffraction peaks were observed by X-ray diffraction; it confirmed the crystalline nature of synthesized gold nanoparticles. The carboxylic, amine, and polyphenolic groups were associated with the algae-assisted synthesized gold nanoparticles which was confirmed using Fourier transform-infrared spectroscopy. This study eliminates the use of chemical substances as reducing and stabilizing agent. Because it has natural several constituents which are fucoidan and polyphenolic substances, it does a dual function as both reducing and stabilizing agent for nanoparticles. Thus, algae-mediated synthesis process of biomedically valuable gold nanoparticles is a one-spot, facile, convenient, large-scaled, and eco-friendly method.