Determination of the strain generated in InAs/InP quantum wires: prediction of nucleation sites

The compositional distribution in a self-assembled InAs(P) quantum wire grown by molecular beam epitaxy on an InP(001) substrate has been determined by electron energy loss spectrum imaging. We have determined the strain and stress fields generated in and around this wire capped with a 5?nm InP layer by finite element calculations using as input the compositional map experimentally obtained. Preferential sites for nucleation of wires grown on the surface of this InP capping layer are predicted, based on chemical potential minimization, from the determined strain and stress fields on this surface. The determined preferential sites for wire nucleation agree with their experimentally measured locations. The method used in this paper, which combines electron energy loss spectroscopy, high-resolution Z contrast imaging, and elastic theory finite element calculations, is believed to be a valuable technique of wide applicability for predicting the preferential nucleation sites of epitaxial self-assembled nano-objects.     

Conductivity enhancement of carbon nanotube and nanofiber-based polymer nanocomposites by melt annealing

The addition of multi-walled carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs) to polymeric melts offers a convenient route to obtain highly conductive plastics. However, when these materials are melt processed, their conductivity can be lost. Here, it is shown that conductivities can be recovered through melt annealing at temperatures above the polymer's glass transition temperature (T_g). We demonstrate these results for both MWCNT and CNF-based composites in polystyrene (PS). The mechanism behind the conductivity increase is elucidated through modeling. It involves a transition from aligned, unconnected particles prior to annealing to an interconnected network after annealing through viscoelastic relaxation of the polymer. Such re-arrangement is directly visualized for the case of the CNF-based composites using confocal microscopy. The annealing-induced increase in particle connectivity is also reflected in dynamic rheological measurements on both MWCNT and CNF composites as an increase in their elastic moduli at low frequencies.     

Temperature Control of a Thermal Plasma Torch with Inductive Coupling Using the Arduino Board

Plasma torch is a device that transforms electrical energy into heat carried by a gas and its safe operation is necessary to control her temperature. This paper presents the use of the Arduino board in temperature control of a plasma torch through fuzzy control. The plasma torch of this project was built so that a flow of water can circulate through your body, allowing its cooling. The cooling system mounted consists of one radiator, one expansion vase, one water pump and one temperature sensor. The heated water coming the plasma torch is passed by the temperature sensor. This is converted in a voltage and read by an analog input port of the Arduino. This processes the information received and makes the decision to turn on/off the radiator fan and/or powered the frequency inverter water pump to control the temperature. The graph of the fuzzy control showed an oscillation between 104 °F to 122 °F around the chosen reference 113 °F. The results show that it is possible to control the temperature of a plasma torch using the Arduino board and fuzzy logic.     

Influence of ouabain of electrolyte and water transport in the rabbit ileum and colon in vitro and in vivo.

We studied the influence of the Na(+)-K+ pump inhibitor ouabain on water and electrolyte transport in the rabbit distal ileum and proximal colon in vitro and in vivo. Under in vitro conditions, ouabain markedly reduced the absorption of water, sodium, chloride and bicarbonate, and reduced potassium secretion in both the ileum and the colon. In vivo results were similar but less marked than those obtained in vitro, with significant differences only at the level of the distal ileum.     

Ceramic pigments based on chromium doped alkaline earth titanates

In this paper M(Ti_1?xCr_x)O₃ with M=Mg, Ca, Sr, Ba and x=0.01, 0.03, 0.05, 0.1 compositions have been prepared by solid state reaction in order to analyze their reactivity, structure, limit of solid solution, stability and pigmenting properties in conventional ceramic glazes. Cr–MgTiO₃ crystallizes magnesium ilmenite MgTiO₃ (SG=R-3) with residual MgCr₂O₄ spinel that inhibits the Cr entrance in solid solution and do not show pigmenting properties. Cr–CaTiO₃ crystallizes orthorhombic perovskite (SG=Pbnm) pink solid solutions associated to Cr⁴⁺–Ti⁴⁺ substitutions which above x=0.03 unstabilizes in glazes and produce light green shades. Cr–SrTiO₃ crystallizes ideal cubic perovskite (SG=Pm3m) pink solid solutions that unstabilizes in glazes above x=0.01. Finally Cr–BaTiO₃ crystallizes tetragonal perovskite (SG=P4mn) with residual peaks of BaCrO₄ at x=0.1 showing pink solid solutions until x=0.05 that unstabilizes in glazes above x=0.03. All powders show aggregates (between 2–10 μm of size) of fine particles (between 200–1000 nm).     

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     

Comparative Study of Micro- and Nano-structured Coatings for High-Temperature Oxidation in Steam Atmospheres

For many high-temperature applications, coatings are applied in order to protect structural materials against a wide range of different environments: oxidation, metal dusting, sulphidation, molten salts, steam, etc. The resistance achieved by the use of different kind of coatings, such as functionally graded material coatings, has been optimized with the latest designs. In the case of supercritical steam turbines, many attempts have been made in terms of micro-structural coatings design, mainly based on aluminides, and other diffusion coating systems in order to consider alternatives, nano-structured coatings based on Cr and Al compositions and deposited by a physical vapor deposition technique, were assessed to high-temperature oxidation resistance in steam environments. The oxidation kinetics where analyzed for up to 2,000 h at 650 °C by means of gravimetric measurements. The evaporation behavior was also analyzed by thermogravimetric-mass spectrometry. Excellent results where observed for some of the nano-structured coatings tested. Those results where compared to results obtained for micro-structured coatings. Based on that comparison, it was deduced that the nano-structured coatings have a potential application as protective systems in high-temperature steam environments.     

Induction of Vesicle Formation by Exposing Apple Tissue to Vacuum Impregnation

This paper demonstrates that vacuum impregnation of mature apple tissue in the presence of different sugars results in the formation of membrane vesicles inside the cells. Vesiculation is regarded to be a metabolic consequence of the impregnation process. Vesiculation is shown when the endocytic marker FM4-64 was impregnated into the apple tissue together with the sugar solutions. Vesicles were formed at the plasma membrane already 30 min after impregnation and remained inside the cells for at least 24 h, a metabolic process that was inhibited in the presence of chloroquine, a specific endosomic inhibitor. This phenomenon was not dependent on the osmotic strength when sucrose was used for impregnation. However, the vesiculation drastically dropped when a hypertonic trehalose solution was impregnated. We suggest that the impregnated sugars may not totally remain in the extracellular space between the cells, as normally believed, but at least a fraction might be incorporated into the cells.     

Processing influence on dielectric,mechanical, and electrical properties of reduced graphene oxide–TPU nanocomposites

Two different reduced graphene oxides (rGOs) with similar concentration of oxygen and defects and differences in exfoliation were prepared to produce the rGO/thermoplastic polyurethane nanocomposites by solution blending (SB) and melt compounding (MC). Morphology, electrical, and dielectric properties were studied. Large agglomerates have been observed for the composites produced by SB and discrete and low agglomerated rGO particles in the case on the composites produced by MC. These morphological differences justify the observations in hardness, electrical conductivity, and even in the dielectric properties. The composites do not follow Jonscher's universal power law (UPL) and a linear trend between UPL factors (Log A vs n) has been observed for composites produced by SB, however, no trend is observed in the composites produced by MC, being the first time observed. Differences in the tunneling effect and breakage of H-bonds within the polymer can be suggested from the dielectric relaxation characterization. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47220.