Insights into the high-pressure behaviour of solid bromine from hybrid DFT calculations

Understanding the properties of molecular solids at high pressure is a key element in the development of new solid-state theories. However, the most commonly used generalized-gradient approximation (GGA) of the density functional theory (DFT) often fails to correctly describe the behavior of these systems at high pressure. Here we utilize the hybrid DFT approach to model the properties of elemental bromine at high pressure. The calculations reproduce in very good agreement with experiment the properties of the molecular phase I (Cmca symmetry) and its pressure-induced transition into the non-molecular phase II (Immm). The experimentally yet unobserved transition into phase III (I4/mmm) is predicted to occur at 128 GPa, followed by subsequent formation of an fcc lattice at 188 GPa. Analysis of the structure and electronic properties of the modelled phases indicates that the molecular Cmca phase becomes metallic just at the borderline of its stability, and that both Immm and I4/mmm phases are metallic and quasi-2D. Finally, we show that the incommensurate phases of bromine postulated from experiment are transient species which can be viewed as intermediates in the dissociation process occurring at the boundary of the transition from phase I to phase II

Hydroxyapatite Nanopowder Synthesis with a Programmed Resorption Rate

A microwave, solvothermal synthesis of hydroxyapatite (HAp) nanopowder with a programmed material resorption rate was developed. The aqueous reaction solution was heated by a microwave radiation field with high energy density. The measurements included powder X-ray diffraction (PXRD) and the density, specific surface area (SSA), and chemical composition as specified by the inductively coupled plasma optical emission spectrometry technique (ICP-OES). The morphology and structure were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A degradation test in accordance with norm ISO 10993-4 was conducted. The developed method enables control of the average grain size and chemical composition of the obtained HAp nanoparticles by regulating the microwave radiation time. As a consequence, it allows programming of the material degradation rate and makes possible an adjustment of the material activity in a human body to meet individual resorption rate needs. The authors synthesized a pure, fully crystalline hexagonal hydroxyapatite nanopowder with a specific surface area from 60 to almost 240 m2/g, a Ca/P molar ratio in the range of 1.57–1.67, and an average grain size from 6 nm to over 30 nm. A 28-day degradation test indicated that the material solubility ranged from 4 to 20 mg/dm3

Laser and electron beam additive manufacturing methods of fabricating titanium bone implants

Additive Manufacturing (AM) methods are generally used to produce an early sample or near net-shape elements based on three-dimensional geometrical modules. To date, publications on AM of metal implants have mainly focused on knee and hip replacements or bone scaffolds for tissue engineering. The direct fabrication of metallic implants can be achieved by methods, such as Selective Laser Melting (SLM) or Electron Beam Melting (EBM). This work compares the SLM and EBM methods used in the fabrication of titanium bone implants by analyzing the microstructure, mechanical properties and cytotoxicity. The SLM process was conducted in an environmental chamber using 0.4–0.6 vol % of oxygen to enhance the mechanical properties of a Ti-6Al-4V alloy. SLM processed material had high anisotropy of mechanical properties and superior UTS (1246–1421 MPa) when compared to the EBM (972–976 MPa) and the wrought material (933–942 MPa). The microstructure and phase composition depended on the used fabrication method. The AM methods caused the formation of long epitaxial grains of the prior phase. The equilibrium phases ( + ) and non-equilibrium ’ martensite was obtained after EBM and SLM, respectively. Although it was found that the heat transfer that occurs during the layer by layer generation of the component caused aluminum content deviations, neither methods generated any cytotoxic effects. Furthermore, in contrast to SLM, the EBM fabricated material met the ASTMF136 standard for surgical implant applications.peer-reviewe

EX-POST EVALUATION OF THE DIRECT ACTIONS OF THE JOINT RESEARCH CENTRE UNDER THE SEVENTH FRAMEWORK PROGRAMMES 2007-2013

The ex-post evaluation in this report provides the independent assessment requested in the Council Decisions concerning the specific programmes to be carried out by means of direct actions by the Joint Research Centre implementing the Seventh Framework Programmes (2007-2013) of the European Community and of the European Atomic Energy Community (Euratom). The evaluation has been conducted by a panel of independent external experts under the chairmanship of Professor Patrick Cunningham. In this report the Panel concludes positively on the effectiveness of the JRC as the Commission’s science service in support of Euratom and EU policies. It also concludes that the JRC has a respectable scientific performance in its areas of competence. In particular, the JRC standard is high as regards the scientific quality and impact of its publications. Besides a number of recommendations for incremental improvement of the JRC the Panel also flags two issues with a view to transformative change of the JRC. To begin with the JRC should establish a long-term strategy before the mid-term evaluation of the Horizon 2020 framework programme in 2017. As the JRC further develops its function as scientific service of the Commission, there is a need to address the JRC’s governance as well as its interaction with the scientific community in the Member States. In light of this the Commission should task a Group of eminent personalities to put forward options for JRC governance, adapted to its functions of the future. These include scientific support, research, scientific advice, and knowledge management in partnership with the Member StatesJRC.ADV02-Adviser for Evaluation and Scientific Integrit

EX-POST EVALUATION OF THE DIRECT ACTIONS OF THE JOINT RESEARCH CENTRE UNDER THE SEVENTH FRAMEWORK PROGRAMMES 2007-2013

The ex-post evaluation in this report provides the independent assessment requested in the Council Decisions concerning the specific programmes to be carried out by means of direct actions by the Joint Research Centre implementing the Seventh Framework Programmes (2007-2013) of the European Community and of the European Atomic Energy Community (Euratom). The evaluation has been conducted by a panel of independent external experts under the chairmanship of Professor Patrick Cunningham. In this report the Panel concludes positively on the effectiveness of the JRC as the Commission’s science service in support of Euratom and EU policies. It also concludes that the JRC has a respectable scientific performance in its areas of competence. In particular, the JRC standard is high as regards the scientific quality and impact of its publications. Besides a number of recommendations for incremental improvement of the JRC the Panel also flags two issues with a view to transformative change of the JRC. To begin with the JRC should establish a long-term strategy before the mid-term evaluation of the Horizon 2020 framework programme in 2017. As the JRC further develops its function as scientific service of the Commission, there is a need to address the JRC’s governance as well as its interaction with the scientific community in the Member States. In light of this the Commission should task a Group of eminent personalities to put forward options for JRC governance, adapted to its functions of the future. These include scientific support, research, scientific advice, and knowledge management in partnership with the Member StatesJRC.ADV02-Adviser for Evaluation and Scientific Integrit

Comparative Laser Spectroscopy Diagnostics for Ancient Metallic Artefacts Exposed to Environmental Pollution

Metal artworks are subjected to corrosion and oxidation processes due to reactive agents present in the air, water and in the ground that these objects have been in contact with for hundreds of years. This is the case for archaeological metals that are recovered from excavation sites, as well as artefacts exposed to polluted air. Stabilization of the conservation state of these objects needs precise diagnostics of the accrued surface layers and identification of original, historical materials before further protective treatments, including safe laser cleaning of unwanted layers. This paper presents analyses of the chemical composition and stratigraphy of corrosion products with the use of laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy. The discussion of the results is supported by material studies (SEM-EDS, XRF, ion-analyses). The tests were performed on several samples taken from original objects, including copper roofing from Wilanów Palace in Warsaw and Karol Poznański Palace in ŁódŸ, bronze decorative figures from the Wilanów Palace gardens, and four archaeological examples of old jewellery (different copper alloys). Work has been performed as a part of the MATLAS project in the frames of EEA and Norway Grants (www.matlas.eu) and the results enable the comparison of the methodology and to elaborate the joint diagnostic procedures of the three project partner independent laboratories

Ab Initio Based Modelling of Diffusion and Phase Stability of Alloys

abstractEN: In this chapter, we present the basic principles and methods for modelling of diffusion and phase stability of alloys using ab-initio methods. We review briefly first-principles methods and their most important approximations. The direct and approximated methods of prediction of migration energies are shown both for pure metals and for alloys. The cluster expansion method is described in more detail. We show that it can be applied to understand interactions in the alloys, to generate the representative structures of alloys and to predict migration barriers in alloys. We describe the methods to compute the effective cluster interactions and to assess the accuracy of the model. Finally, we present the examples of Monte Carlo simulations with parameters obtained from cluster expansion method. We show that the ordering in alloys can be predicted by the calculations of Warren-Cowley parameters. We investigate also the role of entropy in the stability of alloys at elevated temperatures.score: 0collation: 1-2

Electron Microscopy Characterization of the High Temperature Degradation of the Aluminide Layer on Turbine Blades Made of a Nickel Superalloy

The effects of exposure to overheating (temperature above 1000 °C) on the degradation (modification) of layers of coatings (coatings based on aluminum) of uncooled polycrystalline rotor blades of aircraft turbine jet engines were investigated under laboratory conditions. In order to determine the nature of the changes as well as the structural changes in the various zones, a multi-factor analysis of the layers of the coating, including the observation of the surface of the blades, using, among others, electron microscopy, structural tests, surface morphology, and chemical composition testing, was carried out. As a result of the possibility of strengthening the physical foundations of the non-destructive testing of blades, the undertaken research mainly focused on the characteristics of the changes occurring in the outermost layers of the coatings. The obtained results indicate the structural degradation of the coatings, particularly the unfavorable changes, become visible after heating to 1050 °C. The main, strongly interacting, negative phenomena include pore formation, external diffusion of Fe and Cr to the surface, and the formation and subsequent thickening of Fe-Cr particles on the surface of the alumina layer