Synthesis and characterization of hydrophilic nanocomposite coating on glass substrate

Hydrophilic coatings based on 3‐glicidoxy propyl trimethoxy silane (GPTMS) and polyethylene glycol (PEG) were prepared with the incorporation of tetramethoxysilane (TMOS) and silica nanoparticle colloidal suspension by a sol–gel process. Characterization of the coatings has been performed by Fourier Transform Infrared (FTIR) and Attenuated Total Reflectance Infrared (ATR‐IR) techniques. Morphological properties were characterized by Scanning Electron Microscopy (SEM). The distribution of Si atoms in the hybrid system was obtained by Si mapping. The particle size in sol solution of the coating was measured by light scattering analyzer. Optical properties were characterized by using UV–vis spectrophotometer. The hydrophilicity of the coating was determined by contact angle measurements, and also the results have been confirmed by surface energy and water uptake investigations. The obtained results indicate that the surfactants affected the contact angles remarkably but did not change the transparency. It has been found that applying silica nano particles leads to coatings with different properties than those using TMOS, while siloxane contents were the same in these two set of coatings. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5322–5329, 2006     

Pressurized fluid extraction for quantitative recovery of aflatoxins B1 and B2 from pistachio

A pressurized fluid extraction method for the extraction of aflatoxins B₁ and B₂ from contaminated pistachio samples was developed using a modified supercritical fluid extractor. The parameters of temperature, pressure, and flow rate of the solvent were optimized for the extraction process. The pressure variation in the range of (10–100) bar had an insignificant effect on the aflatoxins extraction yield. Solution of 80% (v/v) methanol in water as the extraction solvent at flow rate of 0.5 mL/min and temperatures of higher than 80 °C were obtained for efficient extraction of aflatoxins B₁ and B₂ from spiked and naturally contaminated pistachio samples. The developed method in comparison with the AOAC method offered the repeatability (RSD) of 13.5% and 12%, respectively, while the extraction yield or recovery of the analytes was about 20% higher corresponding to those obtained with the AOAC method. The higher recovery of the developed method was validated by HPLC analysis and it was also applied to the peanut samples analysis.     

Effects of structural variables on AUL and rheological behavior of SAP gels

The swelling properties of superabsorbent polymers (SAPs) under real conditions are extremely important for selecting the material suitable for a given application, e.g. feminine napkin or agriculture. This new practical research represents deeper synthetic and physicochemical studies on the structure–property relation in acrylic SAP hydrogels and composites. Thus, the values of saline‐absorbency under load (AUL; a measurable simulation of the real circumstances of SAP applications, at pressures 0.3–0.9 psi) were measured for the SAP or SAP composite samples prepared under different conditions, i.e. type and content of crosslinker, type and concentration of initiator, percentage of inorganic filler (kaolin), and type and percentage of porosity generators. The samples were subsequently used to determine the rheological and morphological characteristics. Dynamic storage modulus (G′) measurements were carried out at constant strain in a wide range of frequency. Linear correlations were frequently found to be active between AUL and G′ data over the rubber‐elastic plateau. Thus, for a given SAP: AUL = k_totalG′ + C. The coefficient k total is a function of (nature and content of crosslinker, initiator, inorganic component, particle morphology, etc.). Therefore, the easily measured AUL values could be simply correlated to the main synthesis variables and molecular structure of SAP gels through a rheological material function (G′). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Consolidation of nano-crystalline copper powder by cold and hot pressing

This paper investigates preparation of bulk nano-structured Cu through cold and hot pressing. In particular, the effects of different consolidation parameters, such as temperature and pressure, on the properties of bulk nano-structured samples were studied. Microstructure, density, hardness, and electrical conductivity showed strong dependence on the consolidation parameters. All results were compared with those for micron-size Cu powder. Relatively fully dense compacts with minimal grain growth up to 57 nm, maximum hardness of 83 Vickers, and electrical resistivity of 1.93 × 10⁻⁸ Ωm could be achieved.     

Experimental simulation of personal dosimetry in production of medical radioisotopes by research reactor

Due to their work conditions, research reactor personnel are exposed to ionising nuclear radiations. Because the absorbed dose values are different for different tissues due to variations in sensitivity, in this work personal dosimetry has been performed under normal working conditions at anatomical locations relevant to more sensitive tissues as well as for the whole body by employing a Rando phantom and thermoluminescent dosemeters (TLDs). Fifty-two TLDs-100H were positioned at high-risk organ locations such as the thyroid, eyes as well as the left breast, which was used to assess the whole-body dose in order to study the absorbed doses originating from selected locations in the vicinity of the reactor. The results have employed the tissue weighting factors based on International Commission on Radiological Protection ICRP 103 and ICRP 60 and the measured results were below the dose limits recommended by ICRP. The mean effective dose rates calculated from ICRP 103 were the following: whole body, 30.64-6.44 μSv h(-1); thyroid, 1.22-0.23 μSv h(-1); prostate, 0.085-0.045 μSv h(-1); gonads, 1.00-0.51 μSv h(-1); breast, 3.68-0.77 μSv h(-1); and eyes, 33.74-7.01 μSv h(-1).     

Design a 10 kJ IS Mather Type Plasma Focus for Solid Target Activation to Produce Short-Lived Radioisotopes 12C(d,n)13N

A 10 kJ (15 kV, 88 μF) IS (Iranian Sun) Mather type plasma focus device has been studied to determine the activity of a compound exogenous carbon solid target through ¹²C(d,n)¹³N nuclear reaction. The produced ¹³N is a short-lived radioisotope with a half-life of 9.97 min and threshold energy of 0.28 MeV. The results indicate that energetic deuterons impinging on the solid target can produce yield of $ \langle y\rangle $  = 6.7 × 10^?5 with an activity of A = 6.8 × 10⁴ Bq for one plasma focus shut and A _ν  = 4 × 10⁵ Bq for 6 shut per mint when the projectile maximum deuterons energy is E _max = 3 MeV.     

Preparation and mechanical properties of SiC-reinforced Al6061 composite by mechanical alloying

In this paper, an Al6061–10 wt% SiC composite was prepared using the mechanical alloying route. The morphology and the structure of the prepared powder, which change with milling time, were evaluated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, respectively. Moreover, the relationships among the stages of mechanical alloying (MA), relative density and hardness of both pressed and hot extruded materials were investigated. The morphological evolutions showed that relatively equiaxed powders could be synthesized after 9 h of milling. The evolution of relative density and hardness with milling time is due to the morphological and microstructural changes imposed on the composite powder. High-relative densities are typical of the hot extruded samples. The effect of mechanical alloying process on hardness is more significant compared to reinforcement particles. The aging behaviors of the mechanically alloyed, commercially mixed and unreinforced Al6061 were compared. The results showed that MA composites exhibit no aging-hardenability.     

Nanostructure silver-doped zinc oxide films coating on glass prepared by sol–gel and photochemical deposition process: Application for removal of mercaptan

Silver-doped zinc oxide (SDZO) films have been grown on glass substrate by a novel combination of sol–gel and photochemical deposition processes (SGPD). The effect of sintering on structural, electrical and optical properties was investigated. The films were characterized by UV–vis absorption spectroscopy (UV–vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The result of X-ray photoelectron spectroscopy (XPS) revealed that the binding energy of Ag 3d_5/2 for SDZO shifts remarkably to the lower binding energy compared to the pure metallic Ag due to the interaction between silver and zinc oxide. The XRD spectra of the SDZO films indicate that silver was incorporated in the hexagonal crystal structure of zinc oxide. SEM micrographs show the uniform distribution of spherical grains of about 73 nm grain size for the pure zinc oxide thin films. The results indicated that silver doping photochemical deposition was a feasible method to tune the optical properties of zinc oxide nanostructures. SDZO films coated on glass were applied for the photodegradation of mercaptan in water. SDZO films were applied for degradation of mercaptobenzoxazole which reduced the mercaptan concentration to more than 98%.     

Influence of Al2O3 nanoparticles on solubility extension of Cr in Cu by mechanical alloying

In this study, the effect of the presence of Al₂O₃ nanoparticles during mechanical alloying on the extension of Cr solid solubility in Cu was investigated. The lattice parameter, dislocation density and crystallite size were evaluated by the X-ray diffraction technique. Also, the microstructure was characterized by scanning electron microscopy and transmission electron microscopy. The final product was a nanocrystalline and supersaturated Cu–Cr solid solution with a mean crystallite size ranging from 8 to 19 nm depending on the composition. The Gibbs free energy changes in these systems due to the dislocation density and crystallite size variations during milling were calculated. It was found that the presence of Al₂O₃ nanoparticles was beneficial to the process, and this was particularly related to its significant contribution to the increase of strain part of Gibbs free energy changes.