Vibrating reed study of the flux line dynamics of κ-(ET)2Cu[N(CN)2]Br

Vibrating reed measurements were performed on single-crystal samples ofκ-(ET)₂- Cu[N(CN)₂]Br in an applied magnetic fieldH oriented either parallel (“longitudinal”) or perpendicular (“transverse”) to the highly conducting ac-plane. Field-cooling data taken for the longitudinal orientation andH<0.7 T revealed a peak with a low-temperature shoulder in the reed dissipation 1/Q located at temperatureT _Q below the superconducting transition temperatureT _c (≈11.6 forH=0). The shoulder disappeared nearH≈0.7 T, accompanied by an abrupt change in the slope ofT _Q (H), corresponding to a similar change in the slope of the upper critical magnetic fieldH _c2 measured by Kwoket al. The existence of the shoulder in the dissipation peak bears on a number of current explanations for the exotic superconducting properties ofκ-(ET)₂Cu[N(CN)₂]Br.T _Q data taken for the transverse orientation fell far below estimates ofH _c2., indicating the existence of a substantial region of flux line (FL) mobility belowH _c2(T). The location of a peak in NMR relaxation observed by De Sotoet al. lies close toT _Q for the transverse orientation.     

New patents of the “West Siberian Iron and Steel Works” Joint Stock Company

News in Science and Engineering

New patents of the West Siberian Iron and Steel Works Joint Stock Company     

Excellent Specific Mechanical and Electrical Properties of Anisotropic Freeze-Cast Native and Carbonized Bacterial Cellulose-Alginate Foams

Native and carbonized freeze-cast bacterial cellulose-alginate (BC-ALG) foams possess an ice-templated honeycomb-like architecture with remarkable properties. Their unique pore morphology consists of two levels of porosity: 20–50 µm diameter pores between, and 0.01–10 µm diameter pores within the cell-walls. The mechanical properties of the BC-ALG foams, a Young's modulus of up to 646.2 ± 90.4 kPa and a compressive yield strength of up to 37.1 ± 7.9 kPa, are high for their density and scale as predicted by the Gibson–Ashby model for cellular materials. Carbonizing the BC-ALG foams in an inert atmosphere at 1000–1200 °C in a second processing step, both pore morphology and mechanical properties of the BC-ALG remain well preserved with specific mechanical properties that are higher than those reported in the literature for similar foams. Also the electrical conductivity of the BC-ALG foams is high at 1.68 ± 0.04 S cm^?1 at a density of only 0.055 g cm^?3, and is found to increase with density as predicted, and as a function of the degree of carbonization determined by both carbonization temperature and atmosphere. The property profile makes freeze-cast BC-ALG foams and their carbonized foams attractive for energy applications and as a sorbent.     

Electrocatalytic applications of platinum-decorated TiO<Subscript>2</Subscript> nanotubes prepared by a fully wet-chemical synthesis

Pt-decorated \(\hbox {TiO}_{2}\) nanotubes Pt@TiO₂ are prepared only by applying a set of facile wet-chemical redox reactions to ion track-etched polycarbonate templates. First, a homogeneous layer of Pt nanoparticles is deposited onto the complex template surface by reducing potassium tetrachloroplatinate with absorbed dimethylaminoborane. Second, the template is coated with a conformal \(\hbox {TiO}_{2}\) layer, using a chemical bath deposition reaction based on titanium(III) chloride. After the removal of the template, the rutile-type \(\hbox {TiO}_{2}\) nanotubes remain decorated with Pt nanoparticles and nanoparticle-clusters on their outside. During the process, neither vacuum techniques nor external current sources or addition of heat are employed. The crystallinity, composition, and morphology of the composite nanotubes are analysed by X-ray diffraction, scanning and transmission electron microscopy as well as by energy-dispersive X-ray spectroscopy. Finally, the obtained materials are examplarily applied in the electrooxidation of ethanol and formic acid, and their performances have been evaluated. Compared to conventional carbon black-supported Pt nanoparticles, the Pt@TiO₂ nanotubes show higher reaction rates. Mass activities of 2.36 \(\hbox {A}\hbox { mg}_{\rm Pt}^{-1}\hbox { cm}^{-2}\) are reached in ethanol oxidation and 7.56 \(\hbox {A}\hbox { mg}_{\rm Pt}^{-1}\hbox { cm}^{-2}\) in the formic acid oxidation. The present structures are able to exploit the synergy of Pt and \(\hbox {TiO}_{2}\) with a bifunctional mechanism to result in powerful but easy-to-fabricate catalyst structures. They represent an easily producible type of composite nanostructures which can be applied in various fields such as in catalytics and sensor technology.     

The First European Parabolic Flight Campaign with the Airbus A310 ZERO-G

Aircraft parabolic flights repetitively provide up to 23 seconds of reduced gravity during ballistic flight manoeuvres. Parabolic flights are used to conduct short microgravity investigations in Physical and Life Sciences and in Technology, to test instrumentation prior to space flights and to train astronauts before a space mission. The use of parabolic flights is complementary to other microgravity carriers (drop towers, sounding rockets), and preparatory to manned space missions on board the International Space Station and other manned spacecraft, such as Shenzhou and the future Chinese Space Station. After 17 years of using the Airbus A300 ZERO-G, the French company Novespace, a subsidiary of the ’Centre National d’Etudes Spatiales’ (CNES, French Space Agency), based in Bordeaux, France, purchased a new aircraft, an Airbus A310, to perform parabolic flights for microgravity research in Europe. Since April 2015, the European Space Agency (ESA), CNES and the ‘Deutsches Zentrum für Luft- und Raumfahrt e.V.’ (DLR, the German Aerospace Center) use this new aircraft, the Airbus A310 ZERO-G, for research experiments in microgravity. The first campaign was a Cooperative campaign shared by the three agencies, followed by respectively a CNES, an ESA and a DLR campaign. This paper presents the new Airbus A310 ZERO-G and its main characteristics and interfaces for scientific experiments. The experiments conducted during the first European campaign are presented.     

Phase transformations during processing and in vitro degradation of porous calcium polyphosphates

A 2-Step sinter/anneal treatment has been reported previously for forming porous CPP as biodegradable bone substitutes [9]. During the 2-Step annealing treatment, the heat treatment used strongly affected the rate of CPP degradation in vitro. In the present study, x-ray diffraction and ³¹P solid state nuclear magnetic resonance were used to determine the phases that formed using different heat treating processes. The effect of in vitro degradation (in PBS at 37 °C, pH 7.1 or 4.5) was also studied. During CPP preparation, β-CPP and γ-CPP were identified in powders formed from a calcium monobasic monohydrate precursor after an initial calcining treatment (10 h at 500 °C). Melting of this CPP powder (at 1100 °C), quenching and grinding formed amorphous CPP powders. Annealing powders at 585 °C (Step-1) resulted in rapid sintering to form amorphous porous CPP. Continued annealing to 650 °C resulted in crystallization to form a multi-phase structure of β-CPP primarily plus lesser amounts of α-CPP, calcium ultra-phosphates and retained amorphous CPP. Annealing above 720 °C and up to 950 °C transformed this to β-CPP phase. In vitro degradation of the 585 °C (Step-1 only) and 650 °C Step-2 annealed multi-phase samples occurred significantly faster than the β-CPP samples formed by Step-2 annealing at or above 720 °C. This faster degradation was attributable to preferential degradation of thermodynamically less stable phases that formed in samples annealed at 650 °C (i.e. α-phase, ultra-phosphate and amorphous CPP). Degradation in lower pH solutions significantly increased degradation rates of the 585 and 650 °C annealed samples but had no significant effect on the β-CPP samples.     

Understanding the Influence of User Participation and Involvement on System Success – a Systematic Mapping Study

User participation and involvement in software development are considered to be essential for a successful software system. Three research areas, human aspects of software engineering, requirements engineering, and information systems, study these topics from various perspectives. We think it is important to analyze user participation and involvement in software engineering comprehensively to encourage further research in this area. We investigate the evidence on effects of user participation and involvement on system success and we explore which methods are available in literature. A systematic mapping study was conducted. The systematic search yielded 3,698 hits, from which we identified 289 unique papers. These papers were reviewed by the first author based on inclusion and exclusion criteria. The second author validated the selection of papers by reviewing the reasons for exclusion and inclusion and the corresponding papers on a sample base. 58 of the 289 papers were selected (22 statistical survey and meta-study papers and 36 methods papers). Based on the empirical evidence of the surveys and meta-studies, we developed a meta-analysis of structural equation models. This overview demonstrates that most papers showed positive correlations between aspects of development processes (including user participation) and human aspects (including user involvement) and system success. The analysis of the proposed solutions from the method papers revealed a wide variety of user participation and involvement practices for most activities within software development.     

The warning glove – Development and evaluation of a multimodal action-specific warning prototype

This paper has two objectives: first, to introduce the concept of multimodal action-specific warnings and its prototypic realization in the form of a warning glove and second, to present the main findings of a user study that was conducted to test the warning glove against a conventional warning system. Regarding the first goal, the combination of multimodality and action-specificity was implemented by attaching electronic actuators on a right-handed glove for transmitting visual, auditory and tactile feedback. For the second objective, a user study was conducted to test the hypothesis that the warning glove is capable of obtaining faster responses and to determine the perceptions of the users regarding the appropriateness of the warning glove. The results confirmed the assumption of faster response times and participants perceived the warning glove to be ‘fairly appropriate’. These results warrant further development of this multimodal action-specific warning glove.     

Flow phenomena in the exit zone of a circulating fluidized bed

An experimental investigation of the gas and solids flow in a pilot-scale circulating fluidized bed (CFB) cold model with two different abrupt exit configurations (L-shape and extended top) has been carried out. Measurements of axial pressure profiles, high-speed video images of the flow phenomena at the wall as well as local optical probe measurements inside the exit zone are presented. Contrary to published results obtained in bench-scale CFB risers the axial profiles of the apparent solids volume concentration obtained by pressure measurements showed no indication of an increased solids hold-up in the vicinity of the exit, which confirms the conclusion by Pugsley et al. (Can. J. Chem. Eng. 75 (1997) 1001) that this is a scale effect. The local probe measurements showed the well-known core–annulus flow structure prevailing until the riser top. In the vicinity of the exit this flow structure is superimposed by a strong horizontal velocity component directed to the exit duct. In comparison to the conventional L-shaped abrupt exit the extended top does not increase the solids inventory in the riser.