Comparison of Thin Films of Titanium Dioxide Deposited by Sputtering and Sol–Gel Methods for Waveguiding Applications

Semiconductors - In this work, TiO2 thin films were deposited onto glass substrate by two different techniques: sol–gel dip-coating (SG) and reactive DC magnetron sputtering (Sput). The...     

Preparation of chitosan‐g‐poly(acrylamide)/montmorillonite superabsorbent polymer composites: Studies on swelling,thermal, and antibacterial properties

Superabsorbent composites based on chitosan‐g‐poly(acrylamide) and montorillonite (CTS‐g‐PAAm/MMT) were synthesized through in situ radical polymerization by grafting of crosslinked acrylamide onto chitosan backbone in presence of MMT at different contents. The formation of the grafted network was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetery (DSC). The obtained porous structure was observed by scanning electron microscope (SEM). The presence of clay and its interaction with chitosan‐g‐poly(acrylamide) (CTS‐g‐PAAm) matrix was evidenced by ATR‐FTIR analysis. The morphology was investigated by both X‐ray diffraction (XRD) and SEM analyses. It was suggested the formation of mostly exfoliated structures with more porous structures. Besides, the thermal stability of these composites, observed by TGA analysis, was slightly affected by the clay loading as compared to the matrix. These hydrogel composites were also hydrolyzed to achieve anionic hydrogels with ampholytic properties. Swelling behaviors were examined in doubly distilled water, 0.9 wt % NaCl solution and buffer solutions. The water absorbency of all superabsorbent composites was enhanced by adding clay, where the maximum was reached at 5 wt % of MMT. Their hydrolysis has not only greatly optimized their absorption capacity but also improved their swelling rate and salt‐resistant ability. The hydrolyzed superabsorbent showed better pH‐sensitivity than the unhydrolyzed counterparts. The results of the antibacterial activity of these superabsorbents composites against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), assayed by the inhibitory zone tests, have showed moderate inhibition of the bacteria growth. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39747.     

N-3 Polyunsaturated Fatty Acids Modulate In-Vitro T Cell Function in Type I Diabetic Patients

In this work, we assessed the in-vitro effects of eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3) (final concentration, 15 microM) on T cell blastogenesis, interleukin-2 and -4 (IL-2, IL-4) secretion, fatty acid composition and intracellular oxidative status in type I diabetic patients with or without complications. Con A stimulated lymphocyte proliferation, glucose uptake, intracellular reduced glutathione levels and catalase activity were lower in diabetics as compared to controls, regardless to the presence of complications. EPA and DHA diminished T-lymphocyte proliferation and IL-2 production but enhanced IL-4 secretion in both diabetic and control groups. No changes in the levels of reduced glutathione and in the activities of catalase and SOD were observed in control T cells cultured in the presence of EPA and DHA. However, in diabetic patients, addition of n-3 PUFA to culture induced an increase in T cell levels of reduced glutathione and hydroperoxide, and in activities of catalase and SOD. Low levels of arachidonic acid (C20:4n-6) were found in plasma membrane phospholipids of lymphocytes from diabetic patients compared to controls. Incubation of lymphocytes with EPA and DHA was associated with an incorporation of these fatty acids in membrane phospholipids. In conclusion, the beneficial effects of n-3 PUFA on T cell functions in type I diabetes could be attributed to their suppressive action and modulation of cytokine secretion, and to the improvement of intracellular oxidative status.     

Prediction parameters of dimensioning of insulators under non-uniform contaminated conditions by multiple regression analysis

Surface tracking on solid insulators is one of the most severe breakdown mechanisms. Accurate assessment of real insulation conditions can be achieved by using the statistical techniques that assist the measurement and monitoring of contamination severity, flashover voltage and leakage current.To address the uncertainties that surround the exact physical mechanisms underlying the mathematical models, it has been shown that it is possible to include in the assessment of insulator performance contamination accumulation that is predicted by using a short historical of chemical components and atmospheric conditions. The results from this work are useful to predict the contamination severity, flashover voltage as a function of contamination severity, leakage current as a function of applied voltage, arc length and contamination severity, and especially to predict the flashover current.     

Transfer of Phenolic Compounds from Olive Mill Wastewater to Olive Cake Oil

The transfer of the phenolic compounds from olive mill wastewater (OMW) to oil extracted under microwave from olive cake (OC) was carried out by using the following operations: mixing of the olive mill wastewater with the olive cake, drying of the mixture and recovery by solvent of the olive cake oil enriched by phenolic compounds. In the first part of this work, we made a screening design using a Hadamard matrix to quickly locate the factors influencing the process. Among five potentially influential parameters, we found that only three were actually active (OMW/OC ratio noted R, mixing velocity of mixture Vm and mixing time Tm). In the second part, fractional factorial design (2^5?1) was performed to evaluate the effects of five variables (three of them being selected by screening with exposition time Te and radiation power P) and their eventual interactions. The p value (p < 0.05) indicated that R, P,Te, Vm and Tm had significant effects on the response followed by the interaction effects between R‐P, P‐Te, R‐Vm, Te‐Vm, Te‐Tm, and Vm‐Tm. Under optimal conditions, the addition of OMW to OC increased the phenolic compounds content in the oil from 0.04 ± 0.01 to 0.13 ± 0.02 g/L.     

Effect of Cobalt and Nickel Doping on Structural and Magnetic Properties of Iron Oxide Nanoparticles

Two series samples of Iron Oxide nanoparticles doped with nickel and cobalt with different doping values (x?=?0.01; 0.03; 0.05 and 0.07), were successfully synthesized by using sol–gel method, and then they were characterized by X-ray diffraction, scanning electron and vibrating sample magnetometer (VSM). X-ray diffraction analysis of two series samples showed the formation α-Fe₂O₃ nanoparticles, accompanied by two phases iron spinels, CoFe₂O₄ and NiFe₂O₄. In addition, the variations in grain size were observed for both two series. The observation by scanning electron microscopy reveals a change in the morphology of the grains of all the samples doped, which confirm the cobalt and nickel effect on the morphology of iron oxide nanoparticles. Magnetic measurements which were measured by VSM showed significant magnetic parameters such as coercivity and magnetization besides the ferromagnetic behavior of both two series doped with Cobalt and Nickel.

     

Synthesis and characterisation of highly dispersed Ni/SiO2 catalysts prepared by gas-phase impregnation/decomposition (GPI/D) of a Ni(II) β-diketonate precursor complex

Silica-supported nickel catalysts have been prepared by a solventless technique involving the deposition of the [Ni(tmen)(acac)₂] precursor from the gas phase. According to UV–vis and IR spectroscopy and to elemental analysis, the initial deposition step results in the grafting of Ni(II) complexes on silanol groups to give predominantly [Ni(acac)₂ (Si-OH)₂]⁰ monomeric inner-sphere complexes, with elimination of the neutral (tmen) ligands into the gas phase. Subsequent thermal treatments in oxidising atmospheres causes an oxidative decomposition of the (acac) ligands without nickel desorption or coalescence into oxide crystallites. The ensuing coordinatively unsaturated Ni(II) centres are reduced to Ni(0) by flowing hydrogen at low temperatures (300 °C), yielding nanosized Ni particles as evidenced by TEM and O₂ titration. Thus, the gas-phase deposition technique represents an interesting alternative to conventional wet deposition procedures since it allows one to obtain well-dispersed supported nickel catalysts by reduction at low-temperatures.     

Manganese concentrations in the soil and air in the vicinity of a closed manganese alloy production plant

In Montreal (Canada), the mean annual atmospheric Mn concentrations between 1981 and 1990 were stable, followed by a decrease of almost 50% from 1990 to 1992. The reason for such a decrease in Mn is probably the shutdown of a large manganese alloy production plant in Beauharnois, approximately 25 km from Montreal. The objective of this study is to assess the level of air and soil contamination by Mn in the vicinity of this ferroalloy plant more than 10 years after its closure. Air and soil were sampled over 5 days at two and three sites, respectively. Site 1 was located 10 m NE of the closed plant, in the direction of the prevailing SW-NE winds. Sites 2 and 3 were at 50 and 800 m SE from the plant. Air samples were collected in order to determine total (MnT) and respirable (MnR). Soil samples were taken in the surface and subsurface strata. The results show that site 1 is extremely polluted with a mean Mn concentration in surface strata of 2,66,000+/-45,000 ppm and 2,83,000+/-23,000 ppm in the subsurface strata, while the average MnT and MnR are 21.9+/-13.7 and 3.5+/-3.9 microg/m(3), respectively. The explanation for this contamination is direct deposition on the soil of solid Mn-rich residue and atmospheric erosion of Mn particles. The situation should be remediated by the public authority with high priority.     

Combined Post-harvest Treatments for Improving Quality and Extending Shelf-Life of Minimally Processed Broccoli Florets (<Emphasis Type="Italic">Brassica oleracea var. italica</Emphasis>)

Broccoli is an important source of many nutritional and bioactive compounds. However, its shelf-life is very short due to physicochemical losses and microbiological degradation. This study was undertaken to implement treatments that could improve the quality of ready-to-eat (RTE) broccoli during storage by evaluating the effect of pre-treatment with calcium chloride (CaCl₂) and alginate coating on the physicochemical and microbial properties of RTE broccoli. Broccoli florets were pre-treated with three different concentrations of CaCl₂ (1, 2.5, and 4 g L^?1), then coated with an alginate formulation (13 g L^?1) and stored at 4 °C for 24 days. Texture, color, weight loss, respiration rate, and total mesophilic flora (TMF) counts were evaluated at days 0, 3, 7, 14, and 24 of storage. The obtained results in this study showed that combining pre-treatment with calcium and alginate coating led to reducing the weight loss and respiration rate of broccoli, maintaining its color and texture as well as extending its shelf-life by 6 days. These results not only allowed reducing post-harvest losses resulting in the loss of the product but also have a major impact on the environment and resources involved in the production process.     

Determination of phenolic compounds of ‘Sikitita’ olive leaves by HPLC-DAD-TOF-MS. Comparison with its parents ‘Arbequina’ and ‘Picual’ olive leaves

‘Sikitita’ is a new olive cultivar developed in Spain by crossing the cultivars ‘Picual’ and ‘Arbequina’. The phenolic fraction of olive leaves (Olea europaea L.), is purported to have good anti-oxidative properties which help to prevent several health problems. To our knowledge, no studies are available on the phenolic fraction of ‘Sikitita’ olive leaves or any other new cultivar developed from breeding. Thus, the identification and quantification of the phenolic fraction of ‘Sikitita’ olive leaves by HPLC-DAD-MS were studied and compared with those of its parent cultivars. The three cultivars were grown under the same agronomic and environmental conditions in the same orchard. The quantification was performed using HPLC-DAD, whereas qualitative data were acquired using HPLC-MS. It was thus possible to identify 30 different compounds, two of which have been tentatively characterized for the first time in olive leaves of Spanish cultivars. Significant differences between cultivars were observed for almost all the compounds. Results for ‘Sikitita’ olive leaves presented a higher degree of similarity with respect to ‘Picual’ than to ‘Arbequina’. Further work will monitor the time course of phenolic compounds over the growth period.