Theoretical investigation of nitric oxide interaction with aluminum phthalocyanine

Nitric oxide (NO) is an extremely toxic compound formed during combustion, predominantly at high temperatures, and it is among the most important atmospheric pollutants. However, this compound has interesting biological activities, since it can control important biological processes in living organisms. With the aim of developing new materials that can be used as selective chemical sensors or as biomedical NO delivery agents we carried out a quantum mechanical study of the interaction of NO with aluminum phthalocyanine (AlPc) at B3LYP/6-31G* level. The calculation results show clearly that the complexation of NO with AlPc depends on the latter's oxidation state. NO is more strongly bonded to AlPc in the reduced state (-33.77 kcal/mol) than in the oxidized state (-4.96 kcal/mol). By applying the Fukui function and analysis of the Frontier molecular orbital, it was possible to explain the situation within which nitric oxide interacts with AlPc.     

Pressure-induced changes on the optical properties and microstructure of silica-gel matrices doped with rhodamine 6G

Sol–gel method and high-pressure technique were associated to produce silica compacts with low porosity and doped with rhodamine 6G (R6G). Acid catalyzed solutions of tetraethyl orthosilicate mixed with dye previously dissolved in ethanol were used for the synthesis of doped silica gel. The monolith obtained was comminuted and the powder was compacted between 3.0 and 7.7 GPa, at room temperature, using a toroidal-type high-pressure chamber. Excitation–emission fluorescence spectroscopy was used to investigate the optical properties of R6G embedded in the closed pores of the silica matrix. Measurements of surface areas and pore size distribution for the powders and compacts, using the N₂ isotherms were performed, showing a great reduction in surface area and porosity, after compaction. The dye entrapped in the compacted silica maintains its optical properties similar to that in ethanolic solutions, meaning that the dye is dispersed in a molecular level. Additionally, these samples are optically transparent, hard and resistant to dye leaching and to chemical attacks, being a promising material to be used in optical devices.     

Influence of erbia or europia doping on crystal structure and microstructure of ceria–zirconia (CZ) solid solutions

In this study we have prepared three zirconia–ceria compositions, namely 12, 50 and 80 mole% CeO₂. Along with each pure ceria–zirconia composition we have prepared two parallel erbia- or europia-doped materials in which 0.5 mole% of each of the two starting oxides is replaced by 1 mole erbia or europia.     

Raman investigation of the ageing of Ni-BaTiO<Subscript>3</Subscript> multilayer ceramic capacitors

Ni-BaTiO₃ multilayer ceramic capacitors (MLCC) have been aged at 121 °C and 100% Relative Humidity for 2,600 h. Raman and energy dispersive spectral measurements have been made on both aged and unaged samples. Raman spectra indicate the presence of a coating of substoichiometric SnO _x (1 < x < 2) in the aged samples. Morphological and elemental changes occurring in the MLCC were examined by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Preliminary, frequency dependent dielectric measurements indicate that ageing causes a substantial decrease (about 50%) of the capacitance, even if only surfaces are affected by the ageing phenomenon.     

Estimate of aflatoxin M1 exposure in milk and occurrence in Brazil

The presence of aflatoxin M₁ (AFM₁) was investigated in 125 samples of powdered milk, pasteurized milk and ultra high treated (UHT) milk in the city of São Paulo, and estimates of AFM₁ intake were assessed. The samples were analysed using an immunoaffinity column for cleanup and a HPLC-FLD for determining AFM₁. The quantification limit was 10 ng/kg. AFM₁ was found in 119 (95.2%) at levels ranging from 10 to 200 ng/kg with mean concentration of 31 ng/kg. The average daily intake estimated for AFM₁ was 1 ng/kg bw per day for children and 0.188 ng/kg bw per day for adults.     

Nanometer sized polymer based Schottky junctions

The aim of this work was to realize and characterize rectifying junctions with nanometer thickness based on conducting polymers. Various monolayer films were deposited onto different flat graphite electrodes in order to obtain the Schottky interfaces. The second electrical contact was realized by approaching the monolayer film with sharp tip electrode at nanometric distances, in order to create tunneling barriers. A couple of hundred of junctions were realized following this procedure. The investigated junctions have shown rectifying behavior on the current/voltage characteristics in the 96% of the cases. The analysis of the current/voltage characteristics revealed the typical behavior of Schottky barriers. The ideality factor and the Schottky barrier of the junctions were calculated. Moreover, a linear relationship between the threshold voltage and the tunneling barrier width was revealed. In our knowledge, this is the first report of a Schottky junction realized with a monolayer of polymer film.     

Digitizing Human Behavior with Wireless Sensors in Biogas 2020 Technological Business Model Innovation Challenges

Wireless Personal Communications - The ability to develop innovative Business Models (BMs) with high speed and good Return of Investment has become the cornerstone for the competitiveness of many...     

Effect of the chemical composition of the Sv-08G2S welding wire on the impact toughness of deposited metal

The calculated values of the impact toughness of Mesnager specimens at +20, ?40 and ?60 °C for the sorbite-like metal, deposited in CO₂ with Sv-08G2S wire and similar wires produced by different manufacturers, are presented. The effect of the chemical elements present in the Sv-08G2S wire on the impact toughness of the deposited metal is presented. It is shown that Sv-08G2S welding wire has a considerable reserve to increase the impact toughness of the deposited metal as a result of the optimization of the chemical composition.     

Kinetic behavior of sunflower oil pyrolysis over mesoporous materials

Mesoporous materials type MCM-41 and AlMCM-41 were synthesized by the hydrothermal method and characterized by X-ray diffraction and nitrogen adsorption. Analyses have showed that the hexagonal structures of the materials were preserved and the template completely removed. In this work, the degradation of pure sunflower oil and mixed with mesoporous materials were evaluated. A kinetic study of the oil degradation was performed by thermal analysis under heating rates of 5, 10 and 20 °C min⁻¹ using the model-free kinetic in order to determine the kinetic parameters for this process. From this method, the obtained values of apparent activation energy for sunflower oil/AlMCM-41 was of 167 kJ mol^− 1.