Mediator and catalytic effects of porphyrin modified electrodes on redox LB films

In this work, the mediator and/or catalytic properties of modified ITO electrodes by oxidative electrodeposition of Ni-porphyrins have been analyzed. Thus, monolayers containing viologen or azobenzene derivatives, have been transferred onto the porphyrin modified electrodes by using the Langmuir-Blodgett (LB) technique. Following, the redox processes of these compounds forming the LB films and deposited on the modified electrode and the bare ITO have been investigated.The obtained results reveal not only the excellent mediator character of the porphyrinic electrodeposit throughout the viologen redox processes, but also its the catalytic action over the azobenzene kinetics. Specifically, for the last case, the NiTMPyP films accelerate the azobenzene kinetics up to 100 times with respect to those results obtained in absence of porphyrin.     

Selective separation of yttrium from rare earth elements by ion interaction chromatography. Analytical and larger scale applications

ABSTRACT

New ion interaction chromatographic (IIC) method employing Kromasil 100 C₁₈ column and tetra-n-butylammonium hydroxide (TBAOH) as an ion interaction reagent (IIR) is able to separate yttrium from Rare Earth Elements (REE) as anionic complexes with nitrilotriacetic acid (NTA). New method for the chromatographic determination of Y in REE mixture was devised and validated by the analysis of the certified reference material (CRM). Potential possibilities of the new chromatographic system for larger scale applications including macro-micro events were demonstrated.     

Pathways for fatty acid elongation and desaturation in Neurospora crassa

Neurospora crassa incorporated exogenous deuterated palmitate (16∶0) and ¹⁴C-labeled oleate (18∶1^Δ9) into cell lipids. Of the exogenous 18∶1^Δ9 incorporated, 59% was desaturated to 18∶2^Δ9,12 and 18∶3^Δ9,12,15. Of the exogenous 16∶0 incorporated, 20% was elongated to 18∶0, while 37% was elongated and desaturated into 18∶1^Δ9, 18∶2^Δ9,12, and 18∶3^Δ9,12,15. The mass of unsaturated fatty acids in phospholipid and triacylglycerol is 12 times greater than the mass of 18∶0. Deuterium label incorporation in unsaturated fatty acids is only twofold greater than in 18∶0, indicating a sixfold preferential use of 16∶0 for saturated fatty acid synthesis. These results indicate that the release of 16∶0 from fatty acid synthase is a key control point that influences fatty acid composition in Neurospora.     

The Torque Transmission Capabilities of the Adhesively-Bonded Tubular Single Lap Joint and the Double Lap Joint

With the wide application of fiber-reinforced composite materials in aircraft, space structures and robot arms, the design and manufacture of composite joints have become a very important research area because they are often the weakest areas in composite structures.

In this paper, the stress and torque transmission capabilities of the adhesively-bonded tubular single lap joint and the double lap joint were experimentally tested. In order to compare the experimental results with the calculated results, the stress and torque transmission capabilities were analyzed by the 3-dimensional finite element method taking into consideration the nonlinear properties of the adhesive.

From the experiments it was found that the torque transmission capabilities of the adhesively-bonded double lap joint was 2.7 times as large as that of the single lap joint. Also, it was found that the fatigue limit of the double lap joint was 16 times as large as that of the single lap joint.     

Simple approach for the plasma treatment of polymeric membranes and investigation of the aging effect

The modification of the surface characteristics after treatment with plasma in polymeric materials, such as the aging phenomenon, calls the attention of research in the area of nonthermal plasma technology. In this work, a direct treatment with dielectric-barrier discharge plasma was used on the surfaces of ultrafiltration membranes. The measurements of the contact angle with water, attenuated total reflectance accessory, zeta potential, atomic force microscopy and scanning electron microscopy-MEV were performed on the surfaces to verify changes after plasma treatment and to understand the occurrence and timing of the plasma aging effect. In the analysis of the membrane performance, hydraulic permeation and protein retention tests were performed. The results showed an improvement in wettability and hydrophilic properties in the post-treated membranes. The study of reversibility/aging of the post-plasma surface is important for research that deals with the modification of polymeric membranes. Changes in surface morphology, topography and wettability of the membranes were observed up to seven days after treatment, with a tendency to return to the initial characteristics of the membranes.     

Studies concerning the effect of nitrogen on the oxidation behavior of TiAl-based intermetallics at 900°C

The oxidation behavior of the titanium aluminides Ti-50Al and Ti-48Al-5Nb has been investigated in Ar+20%O₂ and in air at 900°C. Thermogravimetric studies in combination with structural analyses using optical metallography, SEM/EDX and X-ray diffraction show a marked influence of nitrogen on the composition and growth rate of the oxide scales. For a more detailed study concerning the effect of nitrogen on the scale-growth kinetics, thermogravimetrical analyses were carried out during which the gas atmosphere was changed from air to Ar–O₂, and vice versa, without intermediate cooling of the specimen. The results show, that nitrogen adversely affects the formation of the initially formed alumina scale and that it enhances the growth rate of the rapidly growing Ti-rich oxide. This effect was observed in both alloys investigated, although the thermogravimetric results at first sight indicated an opposite effect for the Nb-containing alloy. This apparent contradiction is caused by internal oxidation which occurs in this alloy during exposure in Ar–O₂.     

Effect of surface condition on the oxidation behaviour of MCrAlY coatings

Coatings of the MCrAlY type (M = Ni, Co) are commonly used as overlay coatings and as bond coats (BC's) for ceramic thermal barrier coatings (TBC's) in industrial gas turbines. During high temperature service the MCrAlY coatings form aluminium based surface oxide scales. The technologically most relevant properties of the oxide scales, growth rate and adherence do not only depend on the exact MCrAlY composition but also on the surface condition after coating manufacturing. Depending on the coating manufacturing process, the MCrAlY surfaces may substantially differ in roughness. In addition the coatings may be subjected to surface treatments (e.g. shot peening, grinding or smoothening prior to deposition of TBC). In the present work the effect of the surface roughness commonly prevailing in the case of vacuum plasma sprayed MCrAlY coatings on the morphology and composition of the alumina scales formed during high-temperature oxidation was studied. For this purpose free standing coatings with rough and polished surfaces were oxidised in the temperature range from 800 to 1100 °C with exposure times up to 1000 h. The surface scale composition and morphology were analysed by optical metallography and SEM. Fluorescence spectroscopy was used for stress measurements in the oxide scales. It has been found that the oxide scales formed on rough surfaces of MCrAlY coatings have an intrinsically different morphology and growth rate compared to those formed on the flat ground surfaces.     

Pre-annealing effect of electroless Ni−B deposit as a diffusion barrier for electroplated Cu electrodes

Ni−B film of 1 μm thickness was electrolessly deposited on an electroplated Cu bus electrode. The film, which encapsulates the Cu bus electrodes, prevents Cu oxidation and serves as a diffusion barrier against Cu contamination of the transparent dielectric layer in a plasma display during the firing process at 580 °C. The microstructure of theas-deposited barrier film was amorphous phase and crystallized to Ni and Ni₃B after annealing at 300 °C. The good barrier properties observed here can be explained by Ni₃B precipitates at the grain boundaries acting as a fast diffusion path via pre-annealing at 300 °C before the firing process at 580 °C.     

Flexible multibody simulation using hybrid integration scheme

One issue in the dynamic simulation of flexible multibody system is poor computation efficiency, which is due to high frequency components in the solution associated with a deformable body. Standard explicit numerical methods should take very small time steps in order to satisfy the absolute stability condition for the high frequency components and, in turn, the computational efficiency deteriorates. In this study, a hybrid integration scheme is applied to solve the equations of motion of a flexible multibody system for achieving better computational efficiency. The computation times and simulation results are compared between the hybrid scheme and conventional methods. The results demonstrate that the efficiency of a flexible multibody simulation can be improved by using the hybrid scheme.     

Gaming Social Capital: Exploring Civic Value in Multiplayer Video Games

Recent research suggests that social interactions in video games may lead to the development of community bonding and prosocial attitudes. Building on this line of research, a national survey of U.S. adults finds that gamers who develop ties with a community of fellow gamers possess gaming social capital, a new gaming‐related community construct that is shown to be a positive antecedent in predicting both face‐to‐face social capital and civic participation.