Magnesium-based nanocomposites: A review from mechanical, creep and fatigue properties

The addition of nanoscale additions to magnesium (Mg) based alloys can boost mechanical characteristics without noticeably decreasing ductility. Since Mg is the lightest structural material, the Mg-based nanocomposites (NCs) with improved mechanical properties are appealing materials for lightweight structural applications. In contrast to conventional Mg-based composites, the incorporation of nano-sized reinforcing particles noticeably boosts the strength of Mg-based nanocomposites without significantly reducing the formability. The present article reviews Mg-based metal matrix nanocomposites (MMNCs) with metallic and ceramic additions, fabricated via both solid-based (sintering and powder metallurgy) and liquid-based (disintegrated melt deposition) technologies. It also reviews strengthening models and mechanisms that have been proposed to explain the improved mechanical characteristics of Mg-based alloys and nanocomposites. Further, synergistic strengthening mechanisms in Mg matrix nanocomposites and the dominant equations for quantitatively predicting mechanical properties are provided. Furthermore, this study offers an overview of the creep and fatigue behavior of Mg-based alloys and nanocomposites using both traditional (uniaxial) and depth-sensing indentation techniques. The potential applications of magnesium-based alloys and nanocomposites are also surveyed

Voltammetric aptasensors for protein disease biomarkers detection: a review

"Available online 24 May 2016"An electrochemical aptasensor is a compact analytical device where the bioreceptor (aptamer) is coupled to a transducer surface to convert a biological interaction into a measurable signal (current) that can be easily processed, recorded and displayed. Since the discovery of the Systematic Evolution of Ligands by Enrichment (SELEX) methodology, the selection of aptamers and their application as bioreceptors has become a promising tool in the design of electrochemical aptasensors. Aptamers present several advantages that highlight their usefulness as bioreceptors such as chemical stability, cost effectiveness and ease of modification towards detection and immobilization at different transducer surfaces. In this review, a special emphasis is given to the potential use of electrochemical aptasensors for the detection of protein disease biomarkers using voltammetry techniques. Methods for the immobilization of aptamers onto electrode surfaces are discussed, as well as different electrochemical strategies that can be used for the design of aptasensors.The authors acknowledge the financial support from the Strategic funding of UID/BIO/04469/2013 unit, from Project POCI-01-0145- FEDER-006984 – Associate Laboratory LSRE-LCM funded by FEDER funds through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT - Fundação para a Ciência e a Tecnologia and project ref. RECI/BBB-EBI/ 0179/2012 (project number FCOMP-01-0124-FEDER-027462) and S. Meirinhos's doctoral grant (ref SFRH/BD/65021/2009) funded by Fundação para a Ciência e a Tecnologia

Synthesis, characterization and metal ion detection of novel fluoroionophores based on heterocyclic substituted alanines

The synthesis of new fluorescent probes containing the thiophene and benzoxazole moieties combined with an alanine residue is described. The resulting highly fluorescent heterocyclic alanine derivatives respond via a quenching effect, with paramagnetic Cu(II) and Ni(II) metal ions and with diamagnetic Hg(II), as shown by the absorption and steady-state fluorescence spectroscopy studies. The formation of mononuclear or dinuclear metal complexes was postulated based on the presence of the free carboxylic acid as binding site and also with the interaction with the donor atoms in the chromophore. Interaction with other important biological metal ions such as Zn(II), Ca(II) and Na(I) was also explored.Foundation for Science and Technology (Portugal) for financial support through Centro de Química (UM) and REQUIMTE (UNL) through project PTDC/QUI/66250/2006 and PhD grant to E. Oliveira (SFRH/BD/35905/2007)info:eu-repo/semantics/publishedVersio

Thermal decomposition kinetics of the antiparkinson drug “entacapone” under isothermal and non-isothermal conditions

© 2017 Akadémiai Kiadó, Budapest, Hungary The thermal decomposition kinetics of entacapone (ENT) have been investigated via thermogravimetric analysis under non-isothermal and isothermal conditions which provide useful stability information for their processing in the pharmaceutical industry and also for predicting shelf life and suitable storage conditions. The determination of the kinetic parameters for the decomposition process under non-isothermal conditions in a nitrogen atmosphere at four heating rates (5, 10, 15, and 20 °C min −1 ) was performed. Kinetic parameters of the decomposition process for ENT were calculated through Friedman, Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Li–Tang methods. This work demonstrates that the activation energies calculated from the decomposition reactions by different methods are consistent with each other. Moreover, the thermodynamic functions of the decomposition reaction were also calculated