Carboxymethylcellulose/polyaniline blends. Synthesis and properties

Summary Polyaniline (PANI) as one of the conducting polymers focuses intensive research on both scientific and practical field. There are quite a lot of known hybrid materials of PANI and other polymer systems with various synthetic polymers, which results in blends with various properties. The presented research covers the blends of polyaniline with semisynthetic (carboxymethyl) cellulose (CMC). The system could lead to a new antielectrostatic material with interesting properties and seems to be applicable as an additive for packaging in both food and non-food industry. The final material was obtained using both protonated (HCl) and deprotonated form of polyaniline in its semi-oxidized form of leucoemeraldine. Blending consisted in obtaining of thin layer by slow evaporation of the solvent from a mixture of PANI and CMC. For the main investigation atomic force microscopy (AFM) in non-contact mode was used, which gave the topological information about the surface and also some structural information about the material. The described process seems to be very interesting as a route for obtaining a new hybrid natural/synthetic material with very interesting properties and a potential for application.     

Dependability issues in visual–haptic interfaces

Dependability of a system is commonly referred to its reliability, its availability and its maintenability (RAM), but when this concept is applied to user interfaces there is no common agreement on what aspects of user–system interaction are related to a satisfactory RAM level for the whole system. In particular, when dealing with haptic systems, interface dependability may become a crucial issue in medical and in military domains when life-critical systems are to be manipulated or where costly remote control operations are to be performed, like in industrial processes control or in aerospace/automotive engineering and manufacturing. This paper discusses the role of dependability in haptic user interfaces, aiming to the definition of a framework for the assessment of the usability and dependability properties of haptic systems and their possible correlations. The research is based on the analysis of a visual–haptic-based simulator targeted to maintenance activity training for aerospace industry which is taken as a case study. As a result, we propose a novel framework able to collect and then process relevant interaction data during the execution of haptic tasks, enabling to analyze dependability vs. usability correlations.     

Fusing Landsat and MODIS data to retrieve multispectral information from fire-affected areas over tropical savannah environments in the Brazilian Amazon

ABSTRACT

In this study, the combination of surface reflectance products from Terra- Moderate Resolution Imaging Spectroradiometer and Landsat-Enhanced Thematic Mapper Plus sensors are explored through the Flexible Spatiotemporal DAta Fusion (FSDAF) algorithm within the framework of forest fire studies over tropical savannah environments. Thus, 60 fusion-derived images were generated from four spectral bands [red, near-infrared, shortwave infrared (SWIR₁ and SWIR₂)] and six spectral indices [normalized difference vegetation index, normalized difference moisture index, global environment monitoring index, soil-adjusted vegetation index, normalized burn ratio (NBR), and differenced normalized burn ratio (dNBR)] over two selected study sites. For all fusion processes performed, the actual Landsat images for the corresponding dates are available, which supports validation of the blended images. Additionally, integration of blended spectral indices in the immediate post-fire evaluation and the generation of fire severity were analysed. The blended bands presented correlation and Structure Similarity Index Measure (SSIM) values that were consistently higher than 0.819 and root mean square error values of less than 0.027, which confirms good accuracy levels obtained from the model. Similar correlation and SSIM accuracy levels were observed in the blended indices assessment for both study sites, which enables its values to be well-integrated for an analysis of the immediately post-fire date. However, the fire severity mapping from fused images needs to be carefully implemented since the dNBR index is generally less accurate than other blended indices. FSDAF fusion proved to be a useful alternative to retrieving multispectral information from savannah environments affected by fires.     

Rheological and thermal properties of polypropylene blends based in a low molecular weight EVA

Blends of polypropylene (PP) and poly(ethylene-co-vinyl acetate) (EVA) having a PP/EVA viscosity ratio of 240 were prepared by melt mixing. EVA concentration varies from 2 to 26 wt%. All blends display two-phase structure with quasi-spherical EVA domains evenly distributed in the PP matrix. The diameter of the domains increases with EVA concentration from about 0.4 to 6 μm. Each component crystallizes separately. The melting temperature of PP phase is no noticeably affected by the presence of EVA while the crystallization one gradually increases by 4°C. The dynamic moduli of the blends are well predicted by the emulsion model of Palierne, revealing that the system PP/EVA has a very small interfacial tension. The thermal degradation behavior of the blends, determined by thermogravimetry, shows that the deacylation process in EVA is not affected by the presence of PP while the beginning of the degradation process of PP is increased by up to 20°C due to the presence of EVA. This effect goes along with an increment in the maximum degradation rate of PP.     

Catalytic Performance of Ce1−x Ni x O2 Catalysts for Propane Oxidative Steam Reforming

The model, proposed by Peskov et al. (Catal Today 105:223, 2005) to describe kinetic oscillations observed in the N₂O + H₂ reaction on Ir(110), is used to illustrate the effect of periodic perturbation of the reactant pressures on oscillations. The attention is focused on the conversion of natural period-1 oscillations to period-1 oscillations with the imposed frequency. For this conversion, simultaneous perturbation of both reactant pressures is found to be much more efficient compared to perturbation of one of the pressures.     

LaCoO3 nanosystems by a hybrid CVD/sol-gel approach

LaCoO3 nanosystems are receiving increasing attention for the development of innovative fuel cells and heterogeneous catalysts. In this report, we describe the synthesis of nanophasic LaCoO3 thin films by a hybrid chemical vapor deposition (CVD)/sol-gel (SG) approach. The adopted strategy consists in the CVD of La-O-based systems on SG cobalt oxide xerogels CoOx(OH)y at temperatures as low as 200 degrees C and in the subsequent thermal treatment in air (400-800 degrees C, 2-8 h). In this context, particular attention is devoted to achieving an intimate La/Co intermixing already in the as-prepared systems, in order to favor reactions yielding a single La-Co-O phase with uniform composition. The obtained results point out to the formation of pure and structurally homogeneous LaCoO3 nanosystems after annealing at 700 degrees C, 2 h, with a typical grain-like morphology. More severe thermal treatment resulted in the thermal decomposition of LaCoO3 nanocrystallites.     

Characterization of the catalytic films formed on stainless steel anodes employed for the electrochemical treatment of cuprocyanide wastewaters

Surface composition changes at stainless steel anodes in an electrochemical reactor applied for the electrochemical treatment of cuprocyanide-containing wastewaters operating under different hydrodynamic conditions were investigated. Under highly alkaline conditions in situ generation of a surface film on the anode with catalytic properties towards cyanide electrolysis was observed. X-ray photoelectron spectroscopy (XPS) results demonstrated that only copper oxi-hydroxide compounds constitute the surface film developed on the stainless steel anodes, as no traces of N- and C-containing compounds were observed. The collected XPS spectra revealed relevant details concerning the oxidation states of copper in the film, and the products Cu2O, CuO and Cu(OH)2 were identified on the surface of the anodes. However, the quantitative proportions of the individual products differ and depend on the type of mixing employed during reactor operation.