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

Two dimensional LiMgAs; a novel Topological Quantum Catalyst for Hydrogen Evolution Reaction

Quantum materials such as Topological Insulators (TI) have been promising due to diverse applications of their robust surface/edge states in the bulk (3D) and two-dimensional (2D) regime. Such conducting surface states in 3D systems, host "\textit{electron bath}" which are known to facilitate catalysis. However, the analogous effects in 2D scenarios wherein, conducting helical edge states giving rise to Fermionic accumulation has been scarcely addressed. Using density functional theory based \textit{first-principles} calculations, we demonstrate that, the conducting edge states in 2D TI such as LiMgAs can be exploited to facilitate excellent catalytic response towards Hydrogen evolution reactions. The Gibbs free energy in such cases was found to be as low as $-$0.02 eV which is quite superior as compared to other materials reported in literature. The concept presented herein can be extended to other well known 2D TI and used to realise novel topological quantum catalysts for ultra-high performance and efficient catalytic applications.Comment: 5 pages, 4 figure

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

PROPERTIES OF DIAMOND-LIKE CARBON COATINGS DEPOSITED ON CoCrMo ALLOYS

This paper presents results of the structure analysis and tribological testing of a-C:H type diamond-like carbon (DLC) coatings produced by the Plasma Assisted Chemical Vapour Deposition (PACVD) technology on CoCrMo specimens. The DLC coating structure was studied by observing the surface topography using a scanning electron microscope (SEM) in the SE and STEM modes and a profilometer. Raman spectroscopy provided information on hybridized covalent bonds. The structural analysis involved observing the cross-sections of the coatings using a scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS) to determine the concentration and distribution of the constituent elements in the coating. Wear resistance was studied by applying a T-17 pin-on-plate tribological system: a polymeric pin made of ultra-high-molecular-weight polyethylene (UHMWPE) and a CoCrMo plate with a DLC coating. The testing was conducted under friction conditions using Ringer’s solution as a lubricant. The test results showed that the application of DLC coatings definitely improves the serviceability of a surface

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

Design and Fabrication of TiO₂/Lignocellulosic Carbon Materials:Relevance of Low-temperature Sonocrystallization to Photocatalysts Performance

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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

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Here we present a formal description of Biremis panamae Barka, Witkowski et Weisenborn sp. nov., which was isolated from the marine littoral environment of the Pacific Ocean coast of Panama. The description is based on morphology (light and electron microscopy) and the rbcL, psbC and SSU sequences of one clone of this species. The new species is included in Biremis due to its morphological features; i.e. two marginal rows of foramina, chambered striae, and girdle composed of numerous punctate copulae. The new species also possesses a striated valve face which is not seen in most known representatives of marine littoral Biremis species. In this study we also present the relationship of Biremis to other taxa using morphology, DNA sequence data and observations of auxosporulation. Our results based on these three sources point to an evolutionary relationship between Biremis, Neidium and Scoliopleura. The unusual silicified incunabular caps present in them are known otherwise only in Muelleria, which is probably related to the Neidiaceae and Scoliotropidaceae. We also discuss the relationship between Biremis and the recently described Labellicula and Olifantiella