Mn-doped ZnO nanocrystals embedded in Al2O3: structural and electrical properties

We report on the structural and electrical properties of Mn-doped ZnO/Al(2)O(3) nanostructures produced by the pulsed laser deposition technique. Grazing incidence small angle x-ray scattering (GISAXS) and Rutherford backscattering spectrometry revealed the multilayered structure in as-deposited samples. Annealing of the nanostructures was shown to promote the formation of nanocrystals embedded in the Al(2)O(3) matrix, as was evidenced by GISAXS and high resolution transmission microscopy. Particle-induced x-ray emission analysis showed a doping of 8 at.% Mn in ZnO. Grazing incidence x-ray diffraction and Raman spectroscopy demonstrated that the nanocrystals have the pure wurtzite ZnMnO crystalline phase. Resonant Raman scattering displayed an increase of intensity of the 1LO mode as well as broadening of the 2LO mode related to the size effect. Capacitance-voltage measurements showed carrier retention with a voltage shift higher than those reported for similar systems.     

Experimental Validation of Fuzzy Logic Based Routing Algorithm for Wireless Sensor Network Applied to Indoor Environments

Wireless Personal Communications - This paper focuses on the experimental validation of the Fuzzy Logic Based Routing Algorithm (FLBRA) proposed for wireless sensor networks which operates in...     

Residues of persistent organochlorine contaminants in southern elephant seals (Mirounga leonina) from Elephant Island, Antarctica

Contamination of blubber tissues by organochlorine pesticides (OC) and PCBs was assessed in female and male pups and juveniles, as well as in adult females and subdominant adult males of the Southern elephant seal, Mirounga leonina, from Elephant Island in the Antarctic Peninsula. All residues of persistent organochlorine contaminants analyzed were found in blubber samples, except for beta-HCH, endosulfan II, endrin, heptachlor, and aldrin. The relative concentrations of the analytes detected were sigmaDDT > sigmaPCB > sigmachlordane > mirex > dieldrin > HCB> sigmaendosulfan > methoxychlor > sigmaHCHs > other OC pesticides. OC and PCBs concentrations were 1 or 2 orders of magnitude lower than those found in pinnipeds from northern hemisphere. The ratio sigmaDDT/sigmaPCB was higher in southern elephant seals. The relative importance of some OC residues indicates that pesticides used either currently or in the recent past in countries in the southern hemisphere are the sources of contamination in the Antarctic region. Data showed that concentrations of contaminants generally increased from pups < juveniles < adults and suggested that pups accumulated contaminants through transfer from the mother seals via transplacental and lactational routes.     

Analysis of arsenic, lead and cadmium in wines from the Canary Islands, Spain, by ICP/MS.

Because of their high toxicity, arsenic, lead and cadmium need to be quantified in food and beverages. For the first time, in this study the content of arsenic, lead and cadmium was investigated in 152 wine samples from the Canary Islands, Spain, belonging to eight Denominations of Origin (DO) and four islands by inductively coupled plasma mass spectrometry (ICP-MS). The ranges of concentration found were 0.58-8.45 microg l(-1) for arsenic, 0.20-1.73 microg l(-1) for cadmium and 3.89-159.5 microg l(-1) for lead, and the mean content was 3.13, 0.63 and 28.74 microg l(-1), respectively. None of the wines contained levels above the limits set by the International Office of Vine and Wine (OIV), and thus did not pose a health hazard. Significant differences in mean content of those elements between harvest, type of wine, islands and DO were observed.     

Technological Evaluation of Aqueous Enteric Coating Systems with and Without insoluble Additives

The most recent dispersible enteric polymers such as AQUATERIC, HPMCP HP 55 F, EUDRAGIT L 100 55 and cellulose acetate phthalate (micronized in our laboratory), were evaluated on two different physical and chemical substrates (soluble and insoluble). Four standard formulations were used with and without the most common solid additives such as talc and titanium dioxide.

A good distribution of all coatings was obtained on the both substrates previously studied.

The mechanical properties and the dissolution profile of gastric resistance showed clearly that the methacrylic copolymer-based product is a good alternative to esther celluloses manufactured with the most modern technologies.     

Formation of calcium plumbate: Kinetics and mechanism of reaction

In the presence of excess air the kinetics of reaction between CaO and PbO to form calcium plumbate are governed by the diffusion process described by Jander's kinetic model. The energy of activation of the process, as calculated from the Arrhenius equation, is 50 kcal/mol. In an air and nitrogen atmosphere (ratio 1:16) the reaction rate is 4–5 times slower. It has been shown that formation of calcium plumbate from pure CaO and PbO takes place between 600–800° without formation of intermediate compounds. From the results obtained it is deduced that the mechanism of formation consists of two main stages–diffusion between the CaO and PbO, substantially due to the more diffusible PbO, and chemical reaction in the presence of O₂.