Preparation and characterization of acrylic acid/itaconic acid hydrogel coatings containing silver nanoparticles

Hydrogel silver nanocomposites have been used in applications with excellent antibacterial performance. Acrylic acid (AA)/itaconic acid (IA) hydrogels silver nanocomposites were prepared and applied as a coating on a textile substrate. Hydrogel matrices were synthesized first by the polymerization of an AA/IA aqueous (80/20 v/v) solution and mixed with 2‐2‐azobis(2‐methylpropionamide) diclorohydrate and N,N′‐methylene bisacrylamide until the hydrogel was formed. Silver nanoparticles were generated throughout the hydrogel networks with an in situ method via the incorporation of the silver ions and subsequent reduction with sodium borohydride. Cotton (C) and cotton/polyester (CP) textile fibers were then coated with these hydrogel silver nanocomposites. The influence of these nanocomposite hydrogels on the properties of the textile fiber were investigated by infrared spectroscopy (attenuated total reflectance), scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and antibacterial tests against Pseudomona aeruginosa and Staphylococcus aureus. The better conditions, in which no serious aggregation of the silver nanoparticles occurred, were determined. It was proven that the textiles coated with hydrogels containing nanosilver had an excellent antibacterial abilities. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2713–2721, 2013     

PIFA input bandwidth enhancement by changing feed plate silhouette

2.45 GHz planar inverted-F antenna (PIFA) designs mounted on a 100 mm square ground plane are examined with regard to the feed-element shape influence on the input bandwidth (BW). While the traditional wire-fed PIFA has a BW from about 4 to 12%, the novel PIFAs with diverse feed plates (triangular, bi-triangular, rectangular, rounded-rectangular and U-strip) are designs capable of a much broader BW, between 18 and 25% for some configurations.     

Shrinkage reduction and morphological characterization of PP reinforced with glass fiber and nanoclay using functionalized PP as compatibilizer

This work presents results of shrinkage and structure characteristics of reinforced PP using combinations of glass fiber and nanoclay with functionalized PP as compatibilizer during injection molding. Shrinkage, warpage and structure characteristics of clay-fiber reinforced nanocomposites using PP grafted with 2-[2- (Dimethylamino) ethoxy] ethanol (DMAE) to obtain PPgDMAE as compatibilizer, were analyzed. The glass fiber-nanoclay combinations decrease the PP shrinkage as well as the warpage tendency. Functionalized PP facilitates glass fiber and clay dispersion and intercalation. The crystallization temperature, Tc, increases slightly with respect to pure PP and the degree of crystallinity, Xc, was reduced with the clay content.     

Ozone for Microalgae Biomass Harvesting from Wastewater

The use of ozone has been investigated as a harvesting technique (ozone-flotation) for microalgae recovery from wastewater. This document summarizes the most outstanding results achieved to date by our working group, including the ozone effect on the lipid and fatty acid methyl ester (FAME) content. Additionally, the effect of the initial concentration of microalgal biomass on ozone-flotation was investigated using microalgae Scenedesmus sp. cultured in wastewater. Ozone-flotation required specific conditions to separate biomass from wastewater, depending on the type of microalgae strain, culture (single or mixed) and concentration. The effect of ozone-treatment improved lipid extractability and increased degree of FAME saturation.     

Simulation design of electrical capacitance tomography sensors

The resolution and sensing field of electrical capacitance tomography sensors depends upon the configuration of their electrodes and guards, so optimum design is essential in order to provide improved response. Simulations in 2D and 3D are performed based on the finite element method to study the influence of the electrode, guard size and screen arrangement on the sensor characteristics and the reconstructed image     

A Comparison of the Effects of Pulsed Electric Field and Thermal Treatments on Grape Juice

The work was aimed at comparing the effect of pulsed electric field (PEF) and thermal technologies on physical, chemical, microbiological, and nutritional properties of freshly squeezed grape juice of different varieties when they are applied using continuous flow systems. It has been evidenced that grape variety is a factor to be taken into account when comparing the processing effects of PEF and heat treatments. Nevertheless, results of general and specific microbial populations were not affected by it and followed a very similar trend with each processing treatment. Soluble solids, pH, acidity, and the electrical conductivity of grape juice were not affected by PEF processing. On average, PEF treatment reduced the radical scavenging activity a 9% in front of the 13% of the heat treatment whereas both treatments halved the protein content. Data of vitamin C, total polyphenol, cinnamic acid, free catechin and non-flavonoid content were not enough to show differences between both treatments. However, all these nutritionally related properties share the same behaviour, PEF processing yielded milder values than heat processed samples. Information comparing PEF and thermal processes on food products help to clarify the advantages and disadvantages of each technology even though the disparity in development and use of each one.     

Effect of kaolin nanofiller and processing conditions on the structure,morphology, and biofilm development of polylactic acid

The effect of high energy ball milling, HEBM, and the presence of kaolin on the structure, morphology, and biofilm development of polylactic acid, PLA, were studied. Biofilm development was evaluated in terms of structural and/or morphological variations so as the sole presence of kaolin. Composites based on PLA filled with kaolin were prepared by HEBM followed by hot pressing to obtain films. Structure was studied by X‐ray diffraction and Fourier transformed infrared spectroscopy whereas morphology was inspected by scanning electron microscopy and atomic force microscopy. To study biofilm development on the surface of these materials, Pseudomonas fluorescens B52 were used. The shear forces from the milling process favor kaolin dispersion within the PLA. Longer milling times and cryogenic conditions improve clay dispersion. Subsequent hot pressing process enhances the most ordered structure of PLA (α‐phase) which is also favored with previous milling at longer times and under cryogenic conditions. Changes in P. fluorescens biofilm development are mainly due to modifications of surface properties induced by structural variations, being the most ordered structures those which better support bacterial adhesion and proliferation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42676.     

Multimode Si-wire waveguides for integrated optical delay lines

A delay line of multimode Si-wire waveguide folded with 45deg mirror bends is described. A 17 cm waveguide with a core size of 1times3 mum² was integrated in an area of 0.85 mm². The waveguide generated a constant group delay of 2 ns in the entire C-band with a typical optical loss of 14 dB. It also exhibited an error-free operation for 10 Gbit/s optical data signals.