Influence of culture media on the physical and chemical properties of Ag–TiCN coatings

The aim of this study was to verify the possible physical and chemical changes that may occur on the surface of Ag–TiCN coatings after exposure to the culture media used in microbiological and cytotoxic assays, respectively tryptic soy broth (TSB) and Dulbecco's modified eagle's medium (DMEM). After sample immersion for 24 h in the media, analyses were performed by glow discharge optical emission spectroscopy discharge radiation (GDOES), Rutherford backscattering spectroscopy (RBS) and x-ray photoelectron spectroscopy (XPS). The results of GDOES profile, RBS and XPS spectra, of samples immersed in TSB, demonstrated the formation of a thin layer of carbon, oxygen and nitrogen that could be due to the presence of proteins in TSB. After 24 h of immersion in DMEM, the results showed the formation of a thin layer of calcium phosphates on the surface, since the coatings displayed a highly oxidized surface in which calcium and phosphorus were detected. All these results suggested that the formation of a layer on the coating surface prevented the release of silver ions in concentrations that allow antibacterial activity.IC acknowledges the financial support of FCT-Fundacao para a Ciencia e a Tecnologia through the grant SFRH/BD/67022/2009. REG acknowledges support from Ramon y Cajal programme (RyC2007-0026). This research is sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividade and by national funds through FCT-Fundacao para a Ciencia e a Tecnologia in the framework of the Strategic Projects PESTC/FIS/UI607/2011, PEST-C/EME/UI0285/2011, PTDC/CTM/102853/2008.The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the Project 'BioHealth-Biotechnology and Bioengineering approaches to improve health quality', Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. The authors also thank the project 'Consolidating Research Expertise and Resources on Cellular and Molecular Biotechnology at CEB/IBB', Ref. FCOMP-01-0124-FEDER-027462

Model-Driven Performance Prediction of Systems of Systems

International audienceSystems of Systems exhibit characteristics that pose difficulty in modelling and predicting their overall performance capabilities, including the presence of operational independence, emergent behaviour, and evolutionary development. When considering Systems of Systems within the autonomous defence systems context, these aspects become increasingly critical, as performance constraints are typically driven by hard constraints on space, weight and power. System execution modelling languages and tools permit early prediction of the performance of model-driven systems, however the focus to date has been on understanding the performance of a model rather than determining if it meets performance requirements, and only subsequently carrying out analysis to reveal the causes of any requirement violations. Such an analysis is even more difficult when applied to several systems cooperating to achieve a common goal - a System of Systems (SoS). The successful integration of systems within a SoS context has been identified as one of the most substantial challenges facing military systems development [2]. Accordingly, there is a critical need to understand the non-functional aspects of the SoS (such as quality of service, power, size, cost and scalable management of communications), and to explore how these non-functional aspects evolve under new conditions and deployment scenarios. It is crucial that we develop methodologies for modelling and understanding non-functional properties early in the development and integration cycle to better inform our understanding of the impact of emergent behaviour and evolution within the SoS. We propose an integrated approach to performance prediction of model-driven real time embedded defence systems and systems of systems [1]. Our architectural prototyping system supports a scenario-driven experimental platform for evaluating model suitability within a set of deployment and real-time performance constraints. We present an overview of our performance prediction system, demonstrating the integration of modelling, execution and performance analysis, and discuss a case study to illustrate our approach. Our work employs state-of-the-art model-driven engineering techniques to facilitate SoS performance prediction and analysis at design time, either before the SoS is built and deployed, or during its lifetime when required to evolve. Our model-driven performance prediction platform supports a scenario-driven experimental environment for evaluating a SoS within the context of a specific deployment (modelling geographical distribution) and integration constraints. The main contributions of our work are: (a) a modeling methodology that captures diverse perspectives of the performance modeling of Systems of Systems; (b) a performance analysis engine that captures metrics associated with these perspectives and (c) a case study showing the performance evaluaton of a system of systems and its evolution as a result of the performance analysis. We discuss how our approach to modelling supports the specific characteristics of an SoS, and illustrate this through a case study, based on a "Blue Ocean" scenario, demonstrating how we may obtain performance predictions within a SoS with emergent and evolutionary properties. Within the context of our environment, we define models for the individual systems within our System of Systems, defined for representative workload to predict execution costs, i.e. CPU, memory usage and network usage, within a generic situation. Our modelling environment supports the generation of executable forms of these models, which may then be executed above realistic deployment scenarios in order to obtain predictions of System of System performance

Synthesis and characterisation of a new composite aluminosilicate bioceramic

Vanea E, Tamasan M, Albon C, Simon V. Synthesis and characterisation of a new composite aluminosilicate bioceramic. Journal of Non-Crystalline Solids. 2011;357(22-23):3791-3796.Sol-gel derived 60SiO(2).20Al(2)O(3).10Fe(2)O(3).10Dy(2)O(3) (mol%) glass and vitro-ceramic samples obtained after high temperature treatment were investigated with respect to structure, magnetic behaviour, response to simulated body fluid (SBF) and bovine serum albumin (BSA). After heat treatment, the iron preponderantly crystallises as magnetite and hematite. The field-dependent magnetisation measurements support a soft ferrimagnetic, nearly superparamagnetic behaviour. After soaking in SFB/BSA solutions, the analysis of the outermost surface layer by X-ray photoelectron spectroscopy shows the attachment of the protein and the self-assembly of a calcium containing phase. (C) 2011 Elsevier B.V. All rights reserved

Dispersion and Functionalization of Nanoparticles synthesized by Gas Aggregation Source: Opening new Routes toward the Fabrication of Nanoparticles for Biomedicine

The need to find new nanoparticles for biomedical applications is pushing the limits of the fabrication methods. New techniques with versatilities beyond the extended chemical routes can provide new insight in the field. In particular, gas aggregation sources offer the possibility to fabricate nanoparticles with controlled size, composition, and structure out of thermodynamics. In this context, the milestone is the optimization of the dispersion and functionalization processes of nanoparticles once fabricated by these routes as they are generated in the gas phase and deposited on substrates in vacuum or ultra-high vacuum conditions. In the present work we propose a fabrication route in ultra-high vacuum that is compatible with the subsequent dispersion and functionalization of nanoparticles in aqueous media and, which is more remarkable, in one single step. In particular, we will present the fabrication of nanoparticles with a sputter gas aggregation source using a FeB target and their further dispersion and functionalization with polyethyleneglycol (PEG). Characterization of these nanoparticles is carried out before and after PEG functionalization. During functionalization, significant boron dissolution occurs, which facilitates nanoparticle dispersion in the aqueous solution. The use of different complementary techniques allows us to prove the PEG attachment onto the surface of the nanoparticles, creating a shell to make them biocompatible. The result is the formation of nanoparticles with a structure mainly composed by a metallic Fe core and an iron oxide shell, surrounded by a second PEG shell dispersed in aqueous solution. Relaxivity measurements of these PEG-functionalized nanoparticles assessed their effectiveness as contrast agents for magnetic resonance imaging (MRI) analysis. Therefore, this new fabrication route is a reliable alternative for the synthesis of nanoparticles for biomedicine.This work was supported by the European ERC-2013-SyG 610256 NANOCOSMOS and FET Graphene Flagship and by the Spanish Ministerio de Ciencia e Innovación under projects MAT2014-59772-C2-2-P, MAT2011-29194-C02-02, and CSD2007-00041 (NANOSELECT). B.O. acknowledges financial support from the Sectorial Operational Program for Human Resources Development 2007-2013, cofinanced by the European Social Fund, under project no. POSDRU/107/1.5/S/76841 with the title “Modern Doctoral Studies: Internationalization and Interdisciplinary”. L.M. and E.R. acknowledge the Consejo Superior de Investigaciones Científicas (PIE 201160E085). Dr. L. Gutierrez is gratefully acknowledged for critical reading of the manuscript