n/a

The isoconversional methods (Friedman (FR), Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS)) were applied for evaluating the dependencies of the activation energy (E) on the mass loss (Δm) corresponding to the non-isothermal decomposition of two Zn acetate-based gel precursors for ZnO thin films whose preparation differs by the drying temperature of the liquid sol-precursor (125°C for sample A, and 150°C for sample B). Although both investigated samples exhibit similar decomposition steps, strong differences between E vs. Δm curves as well as among the characteristic parameters of the decomposition steps, directly evaluated from TG, DTG and DTA curves, were put in evidence. © 2007 Springer Science+Business Media LLC.

Here we describe an innovative optoelectronic platform which enables the specific detection of unamplified nucleic acid sequences with the integration of oligonucleotide-derivatized gold nanoparticles, a colour sensor and a light emission source for a colorimetric detection method. This new low cost, fast and simple optoelectronic platform permits detection of less than 1 picomole quantities of nucleic acid without target or signal amplification. ©2007 IEEE.

n/a

In this paper we review the different relativistic and QED contributions to energies, ionic radii, transition probabilities and Landé g-factors in super-heavy elements, with the help of the MultiConfiguration Dirac-Fock method (MCDF). The effects of taking into account the Breit interaction to all orders by including it in the self-consistent field process are demonstrated. State of the art radiative corrections are included in the calculation and discussed. We also study the non-relativistic limit of MCDF calculation and find that the non-relativistic offset can be unexpectedly large.

In this paper we review the different relativistic and QED contributions to energies, ionic radii, transition probabilities and Landé g-factors in super-heavy elements, with the help of the MultiConfiguration Dirac-Fock method (MCDF). The effects of taking into account the Breit interaction to all orders by including it in the self-consistent field process are demonstrated. State of the art radiative corrections are included in the calculation and discussed. We also study the non-relativistic limit of MCDF calculation and find that the non-relativistic offset can be unexpectedly large.Topical Issue on the Atomic Properties of the Heaviest Elements

The transition probabilities of Kα hypersatellite lines and energy shifts with respect to the corresponding diagram lines are computed using the Dirac–Fock model for several values of atomic number Z throughout the periodic table. The influence of the Breit interaction on the Kα₁^h/Kα₂^h line intensity ratio, Kα₁^h and Kα₂^h line energy shifts and Kα₁^h to Kα₂^h line energy splitting is evaluated. Double-K shell hole threshold values for selected elements with 23 ⩽Z⩽ 30, calculated within the same approach, are compared with available experimental results.

The transition probabilities of K&alpha; hypersatellite lines and energy shifts with respect to the corresponding diagram lines are computed using the Dirac&ndash;Fock model for several values of atomic number <I>Z</I> throughout the periodic table. The influence of the Breit interaction on the K&alpha;<SUB>1</SUB><SUP>h</SUP>/K&alpha;<SUB>2</SUB><SUP>h</SUP> line intensity ratio, K&alpha;<SUB>1</SUB><SUP>h</SUP> and K&alpha;<SUB>2</SUB><SUP>h</SUP> line energy shifts and K&alpha;<SUB>1</SUB><SUP>h</SUP> to K&alpha;<SUB>2</SUB><SUP>h</SUP> line energy splitting is evaluated. Double-K shell hole threshold values for selected elements with 23 &les;<I>Z</I>&les; 30, calculated within the same approach, are compared with available experimental results.

Cross-linked polyethylene (XLPE) is currently widely used as an insulating material for power cables due to its good physical properties, however when in use it undergoes an electrical ageing process. Its ability to trap electric charge can give rise to space charge accumulation in the bulk of the polymer and produce localised electric stresses that can lead to cable failure, since the electric field will be increased above the design stress in some regions favouring the initiation of degradation there. In this work the PEA (pulsed electro-acoustic) method was used to compare the charge dynamics in three samples (XLPE cable peelings) aged in different ways (electrothermally in the laboratory, field aged in service and thermally aged in the laboratory). Very different transient behavior was found depending upon the ageing history. This is related to differences in the migration of chemical species in the insulation layer, which are known to act as charge traps. All materials showed heterocharge peaks when the space charge reached stability, the magnitude of which seems to be related to the severity of the ageing.

n/a

n/a

n/a

n/a

We describe a detailed study of scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS) analysis to study composition and structure of 500nm thick polycrystalline GaN samples. The films have been deposited by cyclic-pulsed laser deposition (cyclic-PLD) with a Nd:YAG nanosecond pulsed laser at 1064nm. SEM pictures of the GaN layers revealed a structure composed of grains with typical dimensions of 200nm. Coalescence of the grains was more evident for a 1 mu m thick sample. EDS mapping of the GaN layer was performed for Ga, N, O, and Al and could be related with the corresponding SEM scan. Both EDS and XPS composition analyses pointed to a Ga rich (or N deficient) GaN layer. (c) 2007 Elsevier Ltd. All rights reserved.

The possibility of preparation of ophthalmic drug delivery systems using compressed anti-solvent technology was evaluated. Eudragit RS 100 and RL 100 were used as drug carriers, acetazolamide was the model drug processed. Compressed anti-solvent experiments were carried out as a semi-continuous or a batch operation from a liquid solution of polymer(s) + solute dissolved in acetone. Both techniques allowed the recovery of composite particles, but the semi-continuous operation yielded smaller and less aggregated populations than the batch operation. The release behaviour of acetazolamide from the prepared microparticles was studied and most products exhibited a slower release than the single drug. Moreover, the release could be controlled to some extent by varying the ratio of the two Eudragit used in the formulation and by selecting one or the other anti-solvent technique. Simple diffusion models satisfactorily described the release profiles. Composites specifically produced by semi-continuous technique have a drug release rate controlled by a diffusion mechanism, whereas for composites produced by the batch operation, the polymer swelling also contributes to the overall transport mechanism. © 2006 Elsevier B.V. All rights reserved.

The possibility of preparation of ophthalmic drug delivery systems using compressed anti-solvent technology was evaluated. Eudragit RS 100 and RL 100 were used as drug carriers, acetazolamide was the model drug processed. Compressed anti-solvent experiments were carried out as a semi-continuous or a batch operation from a liquid solution of polymer(s) + solute dissolved in acetone. Both techniques allowed the recovery of composite particles, but the semi-continuous operation yielded smaller and less aggregated populations than the batch operation. The release behaviour of acetazolamide from the prepared microparticles was studied and most products exhibited a slower release than the single drug. Moreover, the release could be controlled to some extent by varying the ratio of the two Eudragit used in the formulation and by selecting one or the other anti-solvent technique. Simple diffusion models satisfactorily described the release profiles. Composites specifically produced by semi-continuous technique have a drug release rate controlled by a diffusion mechanism, whereas for composites produced by the batch operation, the polymer swelling also contributes to the overall transport mechanism. © 2006 Elsevier B.V. All rights reserved.

Supercritical fluid impregnation was tested to prepare a new ophthalmic drug delivery device. Poly(methylmethacrylate-co-ethylhexylacrylate-co-ethyleneglycoldimethacr ylate), P(MMA-EHA-EGDMA) has been proposed by Mariz [M. Mariz, Preparação de uma lente intra-ocular dotada de um sistema de libertação controlada de fármaco, Master Thesis, Universidade de Coimbra, 1999] as a promising matrix to be used for intraocular delivery of anti-inflammatory drugs used in eye surgery. This matrix was successfully impregnated with flurbiprofen, a non-steroidal anti-inflammatory agent. The success of the impregnation was evaluated by scanning electron microscopy (SEM) analysis and also by in vitro drug release studies. The effect of some operating parameters was evaluated, namely, pressure and contact time. The operating pressure will influence both the solubility of the drug in the supercritical fluid but also the sorption degree of the polymeric matrix in the presence of carbon dioxide. The solubility of the drug in carbon dioxide and the sorption degree are reported in previous studies. A comparison between the batch and the semi-continuous impregnation process is also presented. The supercritical fluid impregnation proved to be feasible for the preparation of a new ophthalmic drug delivery system. The drug release profiles suggest that the drug can be released up to three months, which is a major advantage for the prevention of the inflammatory response after ophthalmic surgery. © 2007 Elsevier B.V. All rights reserved.

n/a

Algunos de los fenómenos donde el concepto de “globalización” es aplicado incluyen la internacionalización de los mercados, la globalización de la cultura, el dominio político hegemónico del mundo por algunos estados poderosos, o grupos de estados, el poder creciente de organismos supranacionales, y el desarrollo de una división global de trabajo. De acuerdo con Radice, la globalización é generalmente definida como “un proceso a través de lo cual una proporción creciente de transacciones económicas, sociales e culturales ocurre directamente o indirectamente entre partners de países distintos” (Radice, 2004: 154). Un ponto de partida para entender la división global del trabajo debe ser la investigación de los modos como las empresas se reestructuran, una vez que son los actores-llave en la decisión sobre que trabajo debe ser encontrado y donde. Las “cadenas de valor” descriven cada etapa en el proceso productivo de un producto o un servicio final. La palabra “valor” en la frase “cadena de valor” dice respecto al valor añadido. Cada etapa en la cadena de valor implica recibir inputs, procesarlos, y entonces pasarlos a la unidad siguiente en la cadena, con el valor que está sendo adicionado no proceso. As unidades separadas da cadena de valor pueden estar dentro da misma empresa (in-house) o en distintas empresas (outsourced). Similarmente pueden estar en un mismo local, o en otra localización. La normalización de muchos procesos del negocio, combinada con la digitalización da información y el desarrollo de redes de telecomunicaciones de elevada capacidad ha tornado posible el trabajo tele-mediado, pudiendo este ser externalizado y/o re-localizado, conduciendo à introducción de una división de trabajo internacional no trabajo de procesamiento de información. Esta comunicación presentará algunos resultados derivados do proyecto europeo WORKS, donde son estudiados casos portugueses de empresas que justamente se integran en

n/a

Sauropod dinosaurs were the largest animals ever to inhabit the land, with truly gigantic forms in at least three lineages1, 2, 3. Small species with an adult body mass less than five tonnes are very rare4, 5, and small sauropod bones generally represent juveniles. Here we describe a new diminutive species of basal macronarian sauropod, Europasaurus holgeri gen. et sp. nov., and on the basis of bone histology we show it to have been a dwarf species. The fossils, including excellent skull material, come from Kimmeridgian marine beds of northern Germany6, 7, and record more than 11 individuals of sauropods 1.7 to 6.2 m in total body length. Morphological overlap between partial skeletons and isolated bones links all material to the same new taxon. Cortical histology of femora and tibiae indicates that size differences within the specimens are due to different ontogenetic stages, from juveniles to fully grown individuals. The little dinosaurs must have lived on one of the large islands around the Lower Saxony basin8. Comparison with the long-bone histology of large-bodied sauropods suggests that the island dwarf species evolved through a decrease in growth rate from its larger ancestor.

n/a

n/a

n/a