Chemical characterization and reactivity of iron chelator-treated amphibole asbestos.

Iron in amphibole asbestos is implicated in the pathogenicity of inhaled fibers. Evidence includes the observation that iron chelators can suppress fiber-induced tissue damage. This is believed to occur via the diminished production of fiber-associated reactive oxygen species. The purpose of this study was to explore possible mechanisms for the reduction of fiber toxicity by iron chelator treatments. We studied changes in the amount and the oxidation states of bulk and surface iron in crocidolite and amosite asbestos that were treated with iron-chelating desferrioxamine, ferrozine, sodium ascorbate, and phosphate buffer solutions. The results have been compared with the ability of the fibers to produce free radicals and decompose hydrogen peroxide in a cell-free system in vitro. We found that chelators can affect the amount of iron at the surface of the asbestos fibers and its valence, and that they can modify the chemical reactivity of these surfaces. However, we found no obvious or direct correlations between fiber reactivity and the amount of iron removed, the amount of iron at the fiber surface, or the oxidation state of surface iron. Our results suggest that surface Fe3+ ions may play a role in fiber-related carboxylate radical formation, and that desferrioxamine and phosphate groups detected at treated fiber surfaces may play a role in diminishing and enhancing, respectively, fiber redox activity. It is proposed that iron mobility in the silicate structure may play a larger role in the chemical reactivity of asbestos than previously assumed

Optical properties of MgH2 measured in situ in a novel gas cell for ellipsometry/spectrophotometry

The dielectric properties of alpha-MgH2 are investigated in the photon energy range between 1 and 6.5 eV. For this purpose, a novel sample configuration and experimental setup are developed that allow both optical transmission and ellipsometric measurements of a transparent thin film in equilibrium with hydrogen. We show that alpha-MgH2 is a transparent, colour neutral insulator with a band gap of 5.6 +/- 0.1 eV. It has an intrinsic transparency of about 80% over the whole visible spectrum. The dielectric function found in this work confirms very recent band structure calculations using the GW approximation by Alford and Chou [J.A. Alford and M.Y. Chou (unpublished)]. As Pd is used as a cap layer we report also the optical properties of PdHx thin films.Comment: REVTeX4, 15 pages, 12 figures, 5 table

Toward 100 Gbps wireless networks enabled by millimeter wave traveling wave tubes

New generation networks for 5G need a breakthrough to support the unstoppable increase of internet traffic. Millimeter waves offer multi-GHz bandwidth for multigigabit per second data rate. For the full exploitation of the millimeter wave spectrum, due to the high atmosphere attenuation, high transmission power is needed, not available by solid state devices. Traveling wave tubes are the only enabling devices to create ultracapacity layers to distribute data with data rate at fiber level over wide areas. This paper presents the aims of a new European Commission Horizon 2020 project, ULTRAWAVE, to create for the first time a data layer with area capacity toward 100 Gbps/km2, combining D-band and G-band internet distribution enabled by millimeter wave traveling wave tubes

D-band point to multi-point deployment with G-band transport

The first Point to MultiPoint wireless system at D-band has been designed and is in advanced development. The European Commission H2020 ULTRAWAVE "Ultra capacity wireless layer beyond 100 GHz based on millimeter wave Traveling Wave Tubes"project aims to respond to the demand of high capacity at level of tens of Gigabit per second, in urban areas, where fiber backhaul is not economically viable and high density small cell architectures are deployed. A transmission hub powered by a novel D-band TWTs will feed a number of terminals arbitrarily allocated in the corresponding area sector. This paper illustrates the main characteristics, advantages and networking aspects and provide a summary of the latest results of the ULTRAWAVE project

‘Demand pull’ government policies to support Product-Service System activity: the case of Energy Service Companies (ESCos) in the UK

Product-Service Systems (PSSs) constitute a family of service-based business models designed to satisfy our societal needs in an economically and environmentally sustainable manner. To date however PSS application has remained niche due to a variety of critical barriers. This paper explores how ‘demand pull’ national government policies could support PSS activity by addressing these barriers and cultivating market demand. Lessons are drawn from a case study of how regulatory, economic incentive, informative and procurement policies have supported Energy Service Company (ESCo) activity in the UK; a sub-set of the PSS family focused on energy service provision. Subsequently five policy recommendations are presented to support PSS activity: (1) balancing economic incentives and regulatory disincentives; (2) promoting indirect policy support; (3) redesigning existing market structures; (4) promoting locally-led PSS activity; and (5) creating stable policy frameworks. The paper warns however that national government policy cannot easily address all PSS barriers, such as customer preferences, international developments, technological progress and inherent business model weaknesses, pointing to the need for other complementary solutions. Furthermore, other governance actors beside national government could also implement PSS supporting policies

The 2017 Terahertz Science and Technology Roadmap

Science and technologies based on terahertz frequency electromagnetic radiation (100GHz-30THz) have developed rapidly over the last 30 years. For most of the 20th century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to “real world” applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2016, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 17 sections that cover most of the key areas of THz Science and Technology. We hope that The 2016 Roadmap on THz Science and Technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies