Corrosion behavior of thermoelectric clathrates α- and β-Eu8Ga16−xGe30+x in air

The corrosion of thermoelectric clathrates α- and β-Eu₈Ga_16−xGe_30+x is studied under static air (DSC/TG) up to 650 °C. Oxidation product layers with thicknesses of 10.5 μm (α-Eu₈Ga_16−xGe_30+x) and 4.5 μm (β-Eu₈Ga_16−xGe_30+x) are formed. The oxidation begins at 360 and 380 °C, respectively. XRD pattern of the β-Eu₈Ga_16−xGe_30+x oxidized layer shows Ge and four Eu₂O₃ reflections; while α-Eu₈Ga_16−xGe_30+x data (sample crushed and grinded) shows α-Eu₈Ga_16−xGe_30+x reflections (majority phase), two EuGa_2±xGe_4?x strongest reflections and Ge (minority phases). These results indicate the amount of oxides is very small or they are amorphous. High temperature powder XRD measurements on α-Eu₈Ga_16−xGe_30+x under air confirm the oxidation onset temperature determined in DSC studies.     

Multi-agent quality of experience control

International Journal of Control, Automation and Systems - In the framework of the Future Internet, the aim of the Quality of Experience (QoE) Control functionalities is to track the personalized...     

Software corrections of vocal disorders

We discuss how vocal disorders can be post-corrected via a simple nonlinear noise reduction scheme. This work is motivated by the need of a better understanding of voice dysfunctions. This would entail a 2-fold advantage for affected patients: Physicians can perform better surgical interventions and on the other hand researchers can try to build up devices that can help to improve voice quality, i.e. in a phone conversation, avoiding any surgical treatment. As a first step, a proper signal classification is performed, through the idea of geometric signal separation in a feature space. Then through the analysis of the different regions populated by the samples coming from healthy people and from patients affected by T1A glottis cancer, one is able to understand which kind of interventions are necessary in order to correct the illness, i.e. to move the corresponding feature vector from the sick region to the healthy one. We discuss such a filter and show its performance.     

Double dispatch in C++

Double dispatch is the ability to dynamically select a method not only according to the run‐time type of the receiver (single dispatch), but also according to the run‐time type of the argument. This mechanism unleashes the power of dynamic binding in object‐oriented languages, so enhancing re‐usability and separation of responsibilities. However, many mainstream languages, such as, e.g., C++ and Java, do not provide it, resorting only to single dispatch. In this paper we propose an extension of C++ (also applicable to other object‐oriented languages) that enables double dispatch as a language feature. This yields dynamic overloading and covariant specialization of methods. We define a translation from the new constructs to standard C++ and we present the preprocessor implementing this translation, called doublecpp . The translated code enjoys static type safety and implements the semantics of double dispatch by using only standard mechanisms of static overloading and dynamic binding, with minimal impact on the performance of the program. Copyright © 2006 John Wiley & Sons, Ltd.     

Quantitative Assessment of a Peer-to-peer Cooperative Infrastructure Using Stochastic Well-Formed Nets

Traditional support tools for software engineers, normally based on a client-server architecture, are unsuitable to deal with the new issues emerging from the current (and future) cooperative work scenarios (where connectivity is intrinsically transient, the number of interacting partners dynamically changes, etc.). This paper presents a quantitative assessment of a fully decentralized, peer-to-peer, cooperative infrastructure. Stochastic Well-Formed Nets (SWNs) modelling the new peer-to-peer architecture, and a traditional (client-server) one, are developed and analysed: we used SWNs for their ability to directly exploit the symmetries intrinsically present in the modelled systems, thus greatly reducing the complexity of the analysis. The main goal is to compare the impact of the two alternative protocols on the collaborative work. Together with the performance figures of interest, methodological issues concerning the choice of the most appropriate model abstraction level, the adoption of a compositional modelling approach, and the management of the model complexity are also discussed.     

Biosensors based on membrane-bound enzymes immobilized in a 5-(octyldithio)-2-nitrobenzoic acid layer on gold electrodes

Gold electrodes were modified through chemisorption of 5-(octyldithio)-2-nitrobenzoic acid (ODTNB). ODTNB includes a long chain in a short-length thio acid, providing a heterogeneous-like alkanethiol layer after adsorption on gold electrodes. Membrane-bound enzymes, in particular D-fructose dehydrogenase (FDH), D-gluconate dehydrogenase (GADH), and L-lactic dehydrogenase (cytochrome b2) (Cyb2), were immobilized onto ODTNB-modified gold electrodes simply by adsorption. The short-length thio acid may provide electrostatic interactions with enzyme surface charges, while the alkanethiolate enables hydrophobic interaction with the largely lipophilic, membrane-bound enzymes. The immobilization of FDH, GADH, and Cyb2 onto ODTNB-modified gold surfaces has been studied with the quartz crystal microbalance (QCM). Spectrophotometric and electrochemical assays indicate that the immobilized enzyme retains its enzymatic activity after immobilization onto the ODTNB-modified gold surface. The amount of immobilized (and active) enzyme was estimated from QCM to be of the order of 2.5 x 10(-12)-5.3 x 10(-12) mol x cm(-2). A fructose biosensor was developed, making use of a gold surface modified with ODTNB and fructose dehydrogenase, employing hydroxymethylferrocene as a mediator in solution. Calibration curves exhibited a linear relation between the biosensor response and the substrate concentration up to 0.7 mM. Statistical analysis gave an excellent linear correlation (r = 0.9993) and a sensitivity of 6.1 mM(-1) fructose. The biosensor shows a significant stable catalytic current for at least 25 days.     

Peer reviewed: genetic engineering: the frontier of bioremediation

New molecular tools and an improved understanding of biodegradative processes are slowly increasing prospects for successful technology deployment.     

Dithiobissuccinimidyl propionate as an anchor for assembling peroxidases at electrodes surfaces and its application in a H2O2 biosensor

Exposure of gold surfaces to solutions of dithiobis N-succinimidyl propionate (DTSP) gives rise to the modification of the surface with N-succinimidyl-3-thiopropionate (NSTP) which can, in turn, react with amino groups allowing for the covalent immobilization of enzymes such as horseradish peroxidase (HRP). The coverage of NSTP has been estimated to be of the order of 1.3 x 10(-10) from the charge consumed during its reductive desorption. The binding reaction of HRP with NSTP modified gold surfaces has been studied with the quartz crystal microbalance, and the results suggest that the immobilization process involves two steps in which the first (faster) appears to correspond to the rapid incorporation of the enzyme whereas the second is likely due to the slow incorporation of additional enzyme and/or reorganization of the immobilized layer. Spectrophotometric and electrochemical assays indicate that the immobilized HRP retains its enzymatic activity after immobilization onto the DTSP modified gold surface. The amount of immobilized (and active) HRP was estimated from QCM and spectrophotometric measurements to be of the order of 1.5 x 10(-11) mol/cm2. A peroxide biosensor was developed making use of a gold surface modified with DTSP and HRP employing Os and Ru complexes of 1,10-phenanthroline 5,6-dione (phen-dione) of the type [M(phendione)x(L)3-x]+2 (where L = 1,10-phenanthroline or 2,2'-bipyridine, x = 1-3) as mediators with the quinone moieties being the active component. The efficiency of the mediators increased with increasing number of phendione ligands.     

Septo-optic dysplasia: report of 6 patients studied with MR and discussion on its pathogenesis

OBJECTIVE: Septo-optic dysplasia, which consists of the association of the hypoplasia of the optic nerves and the agenesis of the septum pellucidum, is frequently associated with deficiency of hypothalamic releasing factors. In Magnetic Resonance (MR) of these patients, anomalies in the form and size of the pituitary stalk, adenohypophysis and neurohypophysis are found. Some cases show schizencephaly and it has been proposed as an added component of the syndrome by some authors. This fact has been refuted by others. PATIENTS AND METHODS: We present the clinical and neuroanatomic revision of six children with septo-optic dysplasia studied by MR imaging over the last five years in our Department of Neuropediatrics. The aim was, that through the neuroembryological discussion of the morphopathological aspects of the patients, to determine the malformation and the time in which the injury, which was the underlying cause, occurred. RESULTS: From the six cases, in two only disruptive signs were evident with the optic nerves being affected asymmetrically, disruption of the corpus callosum, falx cerebri indemnity and effects in the cortex conformation. This was opposed to the dysgenic features in the other four cases which had no disruptive features. CONCLUSIONS: Our findings suggest that this entity could be the result of at least two different pathogenic processes, that is, a minor form of holoprosencephaly (dysgenesis) or a disruption which, therefore, occurs later in gestation.