Search

We show theoretically and experimentally how a flat-top second-order response can be achieved with a self-coupled single add-drop ring resonator based on two couplers with different splitting ratios. The resulting device is a 1x1 filter, reflecting light back in the input waveguide at resonating wavelengths in the passbands, and transmitting light in the output waveguide at all other non-resonating wavelengths. Different implementations of the filter have been designed and fabricated on a micron-scale silicon photonics platform. They are based on compact Euler bends - either U-bends or L-bends - and Multi-Mode Interferometers as splitters for the ring resonators. Different finesse values have been achieved by using either 50:50 MMIs in conjunction with 85:15 MMIs or 85:15 MMIs in conjunction with 95:05 double MMIs. Unlike ordinary lowest order directional couplers, the MMIs couple most of the power in the cross-port which make them particularly suitable for the topology of the self-coupled ring, which would otherwise require a waveguide crossing. Experimental results are presented, showing good agreement with simulations. The proposed devices can find applications as wavelength-selective reflectors for relatively broad-band lasers or used as 2x2 add-drop filters when two exact replicas of the device are placed on the arms of a Mach-Zehnder interferometer., 9 pages, 17 references, 12 figures

In this work a new energy deposition treatment for the Serpent 2 Monte Carlo transport code is introduced. The treatment is implemented as a set of energy deposition modes, each of which offers a different combination of accuracy and required computational time. The most accurate mode uses the coupled neutron-photon transport available in Serpent 2. In addition to the new modes, a few other improvements such as a new energy deposition detector response was developed. The energy deposition treatment is demonstrated with simple LWR and LFR assembly level test cases. In the LWR cases the results are compared with MCNP6 on a high-level and a good agreement is achieved. In the LFR case differences in the energy deposition estimates of the different modes are highlighted. Based on the test cases, problems in the energy deposition data with ENDF/B-VII.1 and ENDF/B-VIII.0 are presented. Finally, future work concerning energy deposition capabilities of Serpent 2 are briefly discussed.

Selected set of samples from JET ITER-Like Wall (JET-ILW) divertor tiles exposed in 2015-2016 has been analysed using Thermal Desorption Spectrometry (TDS). The deuterium (D) amounts obtained with TDS were compared with Nuclear Reaction Analysis (NRA). The highest amount of D was found on the top part of inner divertor which has regions with the thickest deposited layers as for divertor tiles removed in 2014. This area resides deep in the scrape-off layer and plasma configurations for the second (ILW-2, 2013-2014) and the third (ILW-3, 2015-2016) JET-ILW campaigns were similar. Agreement between TDS and NRA is good on the apron of Tile 1 and on the upper vertical region whereas on the lower vertical region of Tile 1 the NRA results are clearly smaller than the TDS results. Inner divertor Tile 3 has somewhat less D than Tiles 0 and 1, and the D amount decreases towards the lower part of the tile. The D retention at the divertor inner and outer corner regions is not symmetric as there is more D retention poloidally at the inner than at the outer divertor corner. In most cases the TDS spectra for the ILW-3 samples are different from the corresponding ILW-2 spectra because HD and D-2 release occurs at higher temperatures than from the ILW-2 samples indicating that the low energy traps have been emptied during the plasma operations and that D is either in the energetically deep traps or located deeper in the sample. For complete list of authors see http://dx.doi.org/10.1016/j.nme.2019.03.012

Photodeposition has been demonstrated to be a reliable tool for the growth of co-catalyst nanoparticles on titanium dioxide. The current state of investigation on the technique, however, lacks a comprehensive study on the collective influence of different process parameters, preferring to confront the effect of a single parameter at a time. This paper presents a parametric study on photodeposition of platinum nanoparticles from liquid precursors on ALD-grown titanium dioxide, applicable to the fabrication of photocatalytic composite materials. In the described process, a systematic and rigorous statistical analysis of the photodeposition parameters is conducted, assessing the influential parameters that control and predict the size, density and loading of the deposited nanoparticles. The results are assessed by scanning electron microscopy, statistical analysis of micrographs, and X-ray photoelectron spectroscopy. This confirms the simplicity and the viability of photodeposition as a method for the self-assembly of metal nanoparticles from liquid precursors and provides all-round insight on the role of parameters such as the concentration of sacrificial reagents, the presence of H 2SO 4, and the concentration of the precursor solution, in the chemical and structural properties of the deposited nanoparticles.

The NEREID project (“NanoElectronics Roadmap for Europe: Identification and Dissemination”) is dedicated to mapping the future of European Nanoelectronics. NEREID’s objective is to develop a medium and long term roadmap for the European nanoelectronics industry, starting from the needs of applications to address societal challenges and leveraging the strengths of the European eco-system. The roadmap will also identify promising novel nanoelectronic technologies, based on the advanced concepts developed by Research Centres and Universities, as well as identification of potential bottlenecks along the innovation (value) chain. Industry applications include Energy, Automotive, Medical/Life Science, Security, loT, Mobile Convergence and Digital Manufacturing. The NEREID roadmap covers Advanced Logic and Connectivity, Functional Diversification (Smart Sensors, Smart Energy and Energy for Autonomous Systems), Beyond-CMOS, Heterogeneous Integration and System Design as well as Equipment, Materials and Manufacturing Science. This article gives an overview of the roadmap’s structure and content., Thanks are extended to the support of the EU, which has been funded the NEREID project as a Cooperation and Support action for three years from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 685559.

The main funding for the FinEstBeAMS beamline has been obtained from the European Union through the European Regional Development Fund (project “Estonian beamline to MAX-IV synchrotron”, granted to the University of Tartu) and from the Academy of Finland through the Finnish Research Infrastructure funding projects ( FIRI2010 , FIRI2013 , FIRI2014 ). The authors also acknowledge the funding contributions of the University of Oulu , University of Turku , Tampere University of Technology , the Estonian Research Council ( IUT 2-25 , IUT 2-26 , PRG-111 ), as well as the Estonian Centre of Excellence in Research “Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics” TK141 (2014-2020.4.01.15-0011). The strategic funding of Finnish FIMAX consortium coordinating university , University of Oulu , for beamline personnel is also acknowledged. The authors thank the MAX IV Laboratory for financial and infrastructural support as well as for assistance during the construction of the FinEstBeaMS beamline., FinEstBeAMS is a new materials science beamline at the 1.5 GeV storage ring of the MAX IV Laboratory in Lund, Sweden. It has been built based on grazing incidence monochromatization of synchrotron light, which allows to cover a remarkably wide excitation energy range from ultraviolet to soft x-rays (4.5–1450 eV). A new mobile luminescence spectroscopy end station has been commissioned with design benefitting from the advantages of a high flux elliptically polarizing undulator light source. We report on the design of the luminescence end station, its technical realization and performance achieved so far. Special attention is paid to the experimental challenges for luminescence spectroscopy under grazing incidence excitation conditions. The first luminescence results obtained demonstrate a reliable performance of the advanced setup at FinEstBeAMS., Eesti Teadusagentuur IUT 2-25,PRG-111,IUT 2-26; European Commission; University of Tartu; Academy of Finland FIRI2010,FIRI2013,FIRI2014; Tampereen Teknillinen Yliopisto; Turun Yliopisto; European Regional Development Fund; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

This paper describes the simplified model for burnup-induced fuel rod deformations occurring during base irradiation period, from manufacturing to the beginning of the transient. Model is intended to be used together with a codes that are used for analysis of whole core and plant transients. Model consist of thermal and mechanical parts. Due to the high conductance approximation for the gap conductance, the thermal part of the model can be solved independently from the mechanical model. In this way the use of iterative solvers is avoided and model is simple to implement. Model is verified against FRAPCON simulations and has been integrated to the reactor dynamics code HEXTRAN, in which it provides initial data for fuel behavior module FINIX for transient simulation. Effect of burnup initialization on simulation of reactor transients has been demonstrated with the reactor dynamics code HEXTRAN that uses FINIX as a fuel behavior module.

Corrosion, wear and tribocorrosion behaviours of leaded tin bronze were examined in simulated seawater using alumina counterbody for tribological contact. Active dissolution of alloy and corrosion product development on surfaces were the dominant corrosion mechanisms. Tribological contact with counterbody removed majority of the products, thus contributing to active dissolution of freshly exposed surface. This wear-induced corrosion mechanism contributed to 45% and 60% of total material losses at the two highest potentials, 50 mV and 250 mV vs. Ag/AgCl. Pure wear of alloy occurred in the form of abrasive wear. At anodic potentials under tribological contact, corrosion raised the friction coefficient as compared to pure wear and increased wear of the alloy. These results are presented and discussed in this paper.

Post-irradiation examination (PIE) in the form of transmission electron microscopy (TEM) was used to characterize the microstructure of several specimens of Zircaloy-2 and Zircaloy-2 plus 1% Nb that had previously underwent in-pile creep testing in the HALDEN reactor. The purpose of the examination was to explore a microstructural basis for an apparent substantially increased rate of hardening over that observed with similar materials in the higher fast-flux environments of the ATR or HFIR, and to investigate the increased creep strength exhibited by the Nb-containing alloy relative to pure Zircaloy-2. The analysis of irradiation-induced defects indicated a higher than expected density, which was consistent with the observed high hardening rate. Modeling based on mean field rate theory suggests the lower neutron flux in the HALDEN reactor results in a higher fraction of irradiation-induced defects being available for sink (loop) nucleation and growth.

Erosion, transport and deposition of wall impurities are major concerns in future magnetic fusion devices, both from the perspective of the fusion plasma and the machine wall. An extensive study on molybdenum transport and deposition performed in the TEXTOR tokamak yielded a detailed deposition map that is ideal for benchmark deposition studies. A qualitative benchmark is attempted in this article with the ASCOT code. We set up a full 3D model of the TEXTOR tokamak and studied the influence of different physical mechanisms and their strengths on molybdenum deposition patterns on the simulated plasma-facing components: atomic processes, Coulomb collisions, scrape-off layer (SOL) profiles, source distribution, marker starting energy, radial electric field strength, SOL flow and toroidal plasma rotation. The outcome comprises 13 simulations, each with 100,000 markers. The findings are: • Toroidal plasma movement, either within the LCFS or as SOL flow, is negligible. • SOL profile and marker starting energy have modest impact on deposition. • Source distribution has a large impact in combination with radial electric field profiles. • The E ⇀ × B ⇀ drift has the highest impact on the deposition profiles.

—Volt-ampere characteristics of narrow superconducting titanum wires have been studied experimentally. The narrowest specimens measured by means of high-resistance contacts have revealed a behavior nontrivial for superconductors: the Coulomb blockade. The Coulomb gap size correlates with the frequency of quantum phase slips. The observation confirms the identity of quantum dynamics of charge in the Josephson junctions and in the quasi-one-dimensional superconducting channels in the regime of quantum fluctuations of the order parameter.

In this paper, we present an effective emitter passivation scheme using SiO2/Al2O3/SiNx stacks. Our study shows that SiO2/Al2O3/SiNx stacks can well passivate both p+ and n+ emitters due to an excellent chemical passivation combined with a weak field-effect passivation. Good quality boron and phosphorus emitters were achieved over a broad emitter-doping range, as demonstrated by post-fired emitter saturation current of 20 and 30 fA cm−2, respectively. Based on the results obtained with SiO2/Al2O3/SiNx emitter passivation, we present an industrial roadmap for a p-PERT bifacial cell structure. Using this roadmap, we demonstrate industrial p-PERT bifacial cells with front side efficiency of 20.5%, rear side efficiency of 19.8% (bifaciality factor BF = 0.98) for rear textured cells and 17.5% (BF = 0.85) for rear planar cells. In particular, the cells with bifacial SiO2/Al2O3/SiNx passivation on both p+ and n+ emitters also demonstrate promising performance and a simplified cell process. The results show that SiO2/Al2O3/SiNx emitter passivation scheme is a promising candidate for photovoltaic industry.

Authors kindly acknowledge to the Estonian Research Council ( PUT1096 , IUT2-25 , PUT735 ), the Estonian Centre of Excellence in Research project “Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics (TK141), and the financial support of HZB. We are grateful to the staff of BESSY II for the assistance and co-operation during the synchrotron-based measurements., Here we are reporting solvothermal synthesis derived diluted magnetic and plasmonic Co-Ga co-doped ZnO nanocrystals with high magnetization values (from 1.02 to 4.88 emu/g) at room temperature. Co-Ga co-doped ZnO nanocrystals show up to 2 fold increase in saturation magnetization compared to Co doped ZnO nanocrystals at the same Co concentration, with the observed room temperature magnetization higher than previously reported values for multifunctional magnetic and plasmonic nanocrystals, and the effect of Ga suggesting some role of the correspondingly introduced itinerant charge. While at the lowest Ga content the nanoparticles appear homogeneously doped, we note that already a moderate Ga content of several percent triggers a fraction of Co to segregate in metallic form in the bulk of the nanoparticles. However, the amount of segregated Co is not sufficient to account for the total effect, whereas a dominating contribution to the observed magnetism has to be related to itinerant charge mediated exchange interactions., Eesti Teadusagentuur IUT2-25,PUT1096,PUT735; Estonian Centre of Excellence in Research TK141; HZB; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

International audience; The strain rate history dependency of Hadfield steel is investigated by numerical modeling. A crystal plasticity model is employed to study the effect of strain rate jump/drop on the material's strain hardening and twinning propensity. Single crystal orientations are first examined to assess the importance of the strain rate and its history effects. Then a representative 3D microstructure aggregate is used to investigate the effects of strain rate history in a polycrystalline structure. It was found that strain rate affects the evolution of deformation twins in the microstructure, generating a strain rate history dependent deformation and hardening response. A Hadfield steel used in mineral crushing conditions is also characterized to provide details of the deformation and hardening behavior of the material under realistic low/high strain rate loading conditions. The importance of strain rate changes to strengthening and increasing the hardness of the polycrystal microstructure is discussed and considered from the wear resistance point of view.

To simplify the solution of electromagnetic problems with wire media samples, it is reasonable to treat them as the samples of a homogeneous material without spatial dispersion. The account of spatial dispersion implies additional boundary conditions and makes the solution of boundary problems difficult especially if the sample is not an infinitely extended layer. Moreover, for a novel type of wire media – arrays of randomly tilted wires – a spatially dispersive model has not been developed. Here, we introduce a simplistic heuristic model of wire media samples shaped as bricks. Our model covers WM of both regularly and irregularly stretched wires.

Phase field (PF) models are one of the most popular methods for simulating solidification microstructures due to their fundamental connections to the physics of phase transformations. However, these methods are numerically very stiff due to the multiple length scales in a solidifying material, from the nanoscopic solid-liquid interface, to dendritic structures on the order of hundreds of microns. While this problem can be greatly alleviated by thin-interface analytical treatments of the PF equations, additional numerical methods are required to explore experimentally relevant sample sizes and times scales. It was shown about 18 years ago that the use of dynamic adaptive mesh refinement (AMR) can alleviate this problem by exploiting the simple fact that the majority of the solidification kinetics occur at the solid-liquid interface, which scales with a lower dimensionality than the embedding system itself. AMR methods, together with asymptotic analysis, nowadays provide one of the most efficient numerical strategies for self-consistent quantitative PF modelling of solidification microstructure processes. This paper highlights the latest developments in the AMR technique for 3D modelling of solidification using classical phase field equations. This includes a move away from finite element techniques to faster finite differencing through the use of dynamic mini-meshes which are each associated with each node of a 3D Octree data structure, and distributed MPI parallelism that uses a new communication algorithm to decompose a 3D domain into multiple adaptive meshes that are spawned on separate cores. The numerical technique is discussed, followed by demonstrations of the new AMR algorithm on select benchmark solidification problems, as well as some illustrations of multi-phase modelling using a recently developed multi-order parameter phase field model.

An innovative method to filter gaseous iodine based on a wet electrostatic precipitator (WESP) was developed and tested. It is characterized by an ozone feed located before the WESP inlet to oxidize gaseous iodine into iodine oxide particles. Tests were carried out with titanium dioxide particles, first, and then with gaseous molecular iodine (I2) and methyl iodide (CH3I). The applied electric voltage between the electrodes, the total flow rate inside the WESP, and the injection of water droplets before the WESP were varied. The filtration efficiency based on the number of particles was calculated from ELPI and CPC measurements at the inlet and the outlet of the WESP. To determine the mass filtration efficiency for iodine, ICP-MS analyses were performed. Once the operation parameters were optimised for the tested conditions, the WESP ensured a mass filtration efficiency of 99.9% and a particle number based filtration efficiency up to 99.9% against molecular iodine. The efficiency for the filtration of methyl iodide was not as high. The filtration efficiency data are presented covering the particle size range of 0.04–2 µm.

In this paper, a new simulation technique which can include microstructural inhomogeneity of particulate reinforced composites is proposed to accurately study deformation pattern and damage mechanism in these composites. Three dimensional microstructures constructed from XCT images incorporated into finite element modeling codes with minimal approximation to capture the effects of cluster size, local volume fraction of particles in the cluster and the distance between clusters as relevant statistical quantities describing the microstructural inhomogeneity of particulate reinforced composites. A quantitative parameter as degree of clustering is defined to consider particle clustering effect. The results indicate that the damage growth rate of composite with higher degree of clustering is significantly higher than those composites with lower degree of clustering. It is found that for region with higher degree of clustering and bigger size of clusters, the von Mises stress is higher at the same loading conditionand the growth rate of plastic flow is considerably higher than the other region with lower degree of clustering. Moreover, the dislocation description of deformation in two-phase materials rationalize particle clustering effect on the yield behavior of the particulate reinforced composites and the flow stress in these composites. The macroscopic stresses that lead to the initial yielding in the matrix decrease when clusters closely proximate with bigger size and higher degree of clustering.

Ferroelectric tunnel junctions (FTJs) are promising candidates for nonvolatile memories and memristor-based computing circuits. Thus far, most research has focused on FTJs with a perovskite oxide ferroelectric tunnel barrier. As the need for high-temperature epitaxial film growth challenges the technological application of such inorganic junctions, more easily processable organic ferroelectrics can serve as alternative if large tunneling electroresistance (TER) and good switching durability would persist. This study reports on the performance of FTJs with a spin-coated ferroelectric P(VDF-TrFE) copolymer tunnel barrier. The use of three different bottom electrodes, indium tin oxide (ITO), La0.67Sr0.33MnO3, (LSMO), and Nb-doped SrTiO3 (STO) are compared and it is shown that the polarity and magnitude of the TER effect depend on their conductivity. The largest TER of up to 107% at room temperature is measured on FTJs with a semiconducting Nb-doped STO electrode. This large switching effect is attributed to the formation of an extra barrier over the space charge region in the substrate. The organic FTJs exhibit good resistance retention and switching endurance up to 380 K, which is just below the ferroelectric Curie temperature of the P(VDF-TrFE) barrier.

We present the effect of miscut angle of SiC substrates on N-polar AlN growth. The N-polar AlN layers were grown on C-face 4H-SiC substrates with a miscut towards 〈1¯100〉 by metal-organic vapor phase epitaxy (MOVPE). The optimal V/III ratios for high-quality AlN growth on 1° and 4° miscut substrates were found to be 20,000 and 1000, respectively. MOVPE grown N-polar AlN layer without hexagonal hillocks or step bunching was achieved using a 4H-SiC substrate with an intentional miscut of 1° towards 〈1¯100〉. The 200-nm-thick AlN layer exhibited X-ray rocking curve full width half maximums of 203 arcsec and 389 arcsec for (0 0 2) and (1 0 2) reflections, respectively. The root mean square roughness was 0.4 nm for a 2 μm×2μm atomic force microscope scan., Academy of Finland (grant 297916), Aalto University Science and Technology, Japan Society for the Promotion of Science. Grant-in-Aid for Scientific Research (Grant no. 16H06424), Japan Society for the Promotion of Science. Grant-in-Aid for Scientific Research (Grant no. 17K14110)

This paper presents a new direct electron transfer based-miniaturized glucose/oxygen enzymatic fuel cell (EFC) whose operating ability has been tested in real saliva samples. The bioanode and biocathode are a graphene working electrode and a graphite counter electrode localized on the same screen printed electrode (SPE) modified with poly(vinyl alcohol) N-methyl-4(4′-formylstyryl)pyridinium methosulfate acetal (PVA-SbQ)/cellobiose dehydrogenase from Corynascus Thermophilus (CtCDH) C291Y/AuNPs and with Trametes Hirsuta laccase (ThLac)/AuNPs, respectively. In order to optimize the bioanode, several CDH immobilization procedures were adopted, such as drop-casting, use of Nafion membrane or PVA-SbQ photopolymer. The photopolymer showed the best performance in terms of stability and reliability. As biocathode a partially optimized laccase electrode was employed with the variant that the used nanomaterials allowed to reduce the overpotential of O2/H2O redox reaction catalyzed by Trametes Hirsuta Laccase (ThLac), drop-casted onto the gold nanoparticles (AuNPs) modified SPE. The performances of bioanode and biocathode were tested separately, initially immobilizing the two enzymes onto separated graphene SPEs. An efficient direct electron transfer was achieved for both elements, obtaining an apparent heterogeneous electron transfer rate constant (ks) of 0.99 ± 0.05 s−1 for CtCDH C291Y and 5.60 ± 0.05 s−1 for ThLac. Both electrodes were then assembled in a two compartment EFC obtaining a maximal power output of 5.16 ± 0.15 μW cm−2 at a cell voltage of 0.58 V and an open circuit voltage (OCV) of 0.74 V. Successively, the bioanode and biocathode were assembled in a non-compartmentalized EFC and a remarkable 50% decrease of the maximum power output at the value of 2.15 ± 0.12 μW cm−2 at cell voltage of 0.48 V and an OCV of 0.62 V at pH 6.5 was registered. In order to reduce the cell dimensions in view of its possible integration in biomedical devices, the bioanode and biocaythode were realized by immobilization of both enzymes onto the same SPE. The so miniaturized EFC delivered a maximal power output of 1.57 ± 0.07 μW cm2 and 1.10 ± 0.12 μW cm−2 with an OCV of 0.58 V and 0.41 V in a 100 μM glucose solution and in human saliva, respectively.

Ammonia pretreatment greatly improves enzymatic hydrolysis of grass biomass, but is reported to be ineffective for hardwood biomass. Here, we examined the effectiveness of ammonia pretreatment of biomass from six hardwood species with different contents of xylan and lignin. Ammonia pretreatment greatly improved enzymatic hydrolysis of polysaccharides in birch and willow, but was less effective for acacia, eucalyptus, and poplar. The effectiveness of ammonia pretreatment increased with xylan content but decreased with lignin content of the hardwood species. By adding a recombinant xylanase to the commercial enzyme digestion cocktail, the yield of enzymatic hydrolysis of ammonia-pretreated birch biomass was improved to a similar level to that obtained with grass biomass. Our results indicate that enzymatic hydrolysis of biomass from hardwood species having a relatively high xylan/lignin ratio can be achieved with a xylanase-enriched enzyme cocktail after ammonia pretreatment.

We demonstrate integrated silicon-on-insulator (SOI) spiral waveguides with record-high 2.6-ns/mm2 on-chip delay efficiency performing as delay bank stage in variable optical delay buffering and time-slot interchanger applications with 10-Gb/s optical packets. The micro-scale SOI chip comprises three integrated waveguide delay elements of different lengths, providing variable delays of 6.5, 11.3, and 17.2 ns, respectively. Utilizing two semiconductor optical amplifier Mach-Zehnder interferometer wavelength converters and on-chip packet delay, error-free on-chip variable delay buffering from 6.5 to 17.2 ns and successful time-slot interchanging for 10-Gb/s optical packets are presented.

Methods based on X-ray tomography are developed to study the relevant statistical quantities describing the microstructural inhomogeneity of particulate reinforced composites. The developed methods are applied in estimating microstructural inhomogeneity parameters of composites containing metallic glass particles in metal matrix, extruded in varying pressure loads. This study indicates that the critical characteristics with regard to the effect of particle clustering are cluster size and shape, local volume fraction of particles in the cluster and the distance between clusters. The results demonstrate that the spatial distribution of reinforcement is very uneven and the amount of particle clustering varies with amount of reinforcement. Moreover, X-ray nanotomography was used to investigate the structure of individual clusters and the results suggest that high extrusion load may cause break-up of individual particle clusters so that their shape changes from solid and spherical to broken and ellipsoidal.

—A scanning probe microscopy method that allows one to measure Young’s modulus of thin and flexible nanowires is developed, which consists in measuring the deflection profiles under conditions of precise force control. This method can be applied to any thin and flexible one-dimensional or two-dimensional object. Using this approach, Young’s moduli of thin InP conical nanowires with the wurtzite and zincblende structures are measured. It is found that nanowires with the pure wurtzite structure have a higher value of Young’s modulus than the nanowires containing alternating wurtzite–zincblende phases.

Single crystals of oxygen-free copper oriented to easy glide of dislocations were tensile tested in order to study the hydrogen effects on the strain localisation in the form of slip bands appearin...

Calculations on the global energy consumption due to friction and wear in the mineral mining industry are presented. For the first time, the impact of wear is also included in more detailed calculations in order to show its enormous tribological and economic impacts on this industry. A large variety of mining equipment used for the extraction, haulage and beneficiation of underground mining, surface mining and mineral processing were analysed. Coefficients of friction and wear rates of moving mechanical assemblies were estimated based on available information in literature in four general cases: (1) a global average mine in use today, (2) a mine with today's best commercial technology, (3) a mine with today's most advanced technology based upon the adaptation of the latest R&D achievements, and (4) a mine with best futuristic technology forecasted in the next 10 years. The following conclusions were reached: • Total energy consumption of global mining activities, including both mineral and rock mining, is estimated to be 6.2% of the total global energy consumption. About 40% of the consumed energy in mineral mining (equalling to 4.6 EJ annually on global scale) is used for overcoming friction. In addition, 2 EJ is used to remanufacture and replace worn out parts and reserve and stock up spare parts and equipment needed due to wear failures. The largest energy consuming mining actions are grinding (32%), haulage (24%), ventilation (9%) and digging (8%). • Friction and wear is annually resulting in 970 million tonnes of CO2 emissions worldwide in mineral mining (accounting for 2.7% of world CO2 emissions). • The total estimated economic losses resulting from friction and wear in mineral mining are in total 210,000 million Euros annually distributed as 40% for overcoming friction, 27% for production of replacement parts and spare equipment, 26% for maintenance work, and 7% for lost production. • By taking advantage of new technology for friction reduction and wear protection in mineral mining equipment, friction and wear losses could potentially be reduced by 15% in the short term (10 years) and by 30% in the long term (20 years). In the short term this would annually equal worldwide savings of 31,100 million euros, 280 TWh energy consumption and a CO2 emission reduction of 145 million tonnes. In the long term, the annual benefit would be 62,200 million euros, 550 TWh less energy consumption, and a CO2 emission reduction of 290 million tonnes. Potential new remedies to reduce friction and wear in mining include the development and uses of new materials, especially materials with improved strength and hardness properties, more effective surface treatments, high-performance surface coatings, new lubricants and lubricant additives, and new designs of moving parts and surfaces of e.g. liners, blades, plates, shields, shovels, jaws, chambers, tires, seals, bearings, gearboxes, engines, conveyor belts, pumps, fans, hoppers and feeders. acceptedVersion

The current–voltage characteristics of superconductor–insulator–semiconductor (S1–I–S2) tunnel junctions, where superconducting electrode S2 is a thin nanowire, are studied experimentally. The observed blurring of the gap singularities is interpreted as a manifestation of the order parameter quantum fluctuations. We propose a model taking into account the broadening of the density of states due to the interaction of electrons with the Mooij–Schön plasmon mode emerging in a quasi-one-dimensional superconducting channel in the regime of quantum fluctuations of the order parameter. The model gives results that are in a reasonable qualitative agreement with the experimental data.

The P91 steel is widely used in high temperature components of power plants, and it is a candidate material for Gen-IV reactors. The P91 steel has relatively attractive mechanical and physical properties combined with resistance to stress corrosion cracking in water-steam environments. This study aimed to explore the combined cyclic, creep and relaxation behaviour of P91 material. Uniaxial specimens were subjected to cyclic loadings with periodic forward creep or relaxation at peak stress. The results indicate that prior creep or intermediate relaxation periods up to 72 h will influence the subsequent cyclic softening of P91, but do not significantly reduce the cyclic life. In contrast, prior cycling has a detrimental effect on the subsequent creep life. A simplified creep-fatigue model is shown to predict life better than usual code-based approaches. Improved verification of all models would benefit from the availability of more extensive long-term data on P91 steel.

International audience; The hardening and deformation characteristics of Hadfield microstructure are studied to investigate the effect of microstucture to the material behavior. A crystal plasticity model including dislocation slip and deformation twinning is employed. The role of deformation twinning to the overall strain hardening of the material is evaluated for two different grain structures. Large compressive strains are applied on 3D microstructural aggregates representing the uniform and non-uniform grain structures of Hadfield steels. The grain structure has an effect on the strain hardening rate as well as on the overall hardening capability of the microstructure. A major reason causing the difference in strain hardening arises from the different twin volume fraction evolution influenced by intra-grain and inter-grain interactions. A mixture of large and small grains was found to be more favorable for twinning and thus resulting in a greater hardening capability than uniform grain size.

Laser induced breakdown spectroscopy (LIBS) has been applied to study ITER-relevant coatings with different surface morphology and crystallinity. LIBS elemental depth profiles were compared with those obtained by secondary ion mass spectrometry (SIMS). Depending on surface morphology and crystallinity, the laser ablation rate of the coatings changed by an order of magnitude, the highest ablation rate had samples prepared by thermoionic vacuum discharge. The inclusion of aluminum (proxy for beryllium) increased the ablation rate by a factor of>6. In addition, for W-Al coatings the ablation was non-stoichiometric.

Nanostructured zinc oxide, ZnO, films feature attractive functional properties, but their long-term stability needs further investigation. Here, ZnO thin films with well-aligned rod-like structure were grown on stainless steel substrate. The long-term chemical stability of the ZnO films was investigated in solutions with varying pH values (3 − 11) to enhance knowledge about the durability of films in acidic and basic environments. The solubility and stability of the films in the solutions were investigated using atomic absorption spectrophotometry, scanning electron microscopy imaging and energy-dispersive X-ray spectroscopy analyses, as well as by monitoring changes in water contact angle of the films and in the pH values of the solutions. The ZnO film was found to be most stable at highest pH value, with the amount of dissolved zinc being lowest among the studied pH values and the changes observed with other characterization methods being minor compared to the samples immersed to other solutions. At the lowest pH, the film was removed rapidly from the substrate by dissolution. In solutions featuring pH values 5 and 9, the measured pH was unstable and changed constantly until it reached the value 7.2–7.6, i.e., until the equilibrium of different chemical species in the solution was achieved. These results are presented and discussed in this paper from the viewpoint of applicability of the ZnO films.

Rising computational capabilities have allowed for the possibility of more complex thermal hydraulic safety codes. One of these branches of advancement is to start using three dimensional solvers in system codes instead of one dimensional. CATHARE-2 already included a 3D module, but within the EDF and CEA NEPTUNE project started in 2001 the 3D solver, as a part of CATHARE-3, has been modified to be more versatile and at the same time faster. Moving from one dimensional solvers to three dimensional poses issues due to the added degrees of freedom. In a 3D solver terms describing turbulence appear in the equations due to the time and space averaging inherent to the field equations which need to be taken into account. Within the NURESAFE program turbulence models have been added to the 3D module of CATHARE-3. In this paper the sensitivity of simulation results to the different turbulence models and level of detail in meshing have been studied. For this purpose simulations of boil-up and reflooding experiments performed at the PERICLES 2D facility were carried out. The results show that the turbulence models do cause change in the results. With sub channel level meshing they are visible, while with channel level meshing turbulence modelling has minimal effect.

Continuous-energy Monte Carlo reactor physics code Serpent 2 was used to model the critical steady state conditions measured in V-1000 zero-power critical facility at Kurchatov Institute (KI), Moscow in 1990–1992. The Serpent 2 results were compared to measurements and Serpent 2 was used to generate group constants for reactor dynamics code HEXTRAN. The results of a HEXTRAN calculation of the steady state were compared to Serpent 2. The relative power density distribution of the SERPENT2 calculations compared with the measurements was within the statistical accuracy. The comparison of HEXTRAN and Serpent 2 node-wise relative power density distributions showed an accuracy of ±10%.

Jarosite is a typical stream of zinc refineries, with high production rates and possible release of metal-contaminated seepage waters during long-term storage in respective disposal sites. Jarosite contains remarkable concentrations of valuable metals, like several weight percentages of zinc and lead, in addition to lower concentrations of copper, silver, germanium, gallium and indium. In this study, jarosite was treated with reductive and oxidative bioleaching for valuable metals recovery. The reductive bioleaching was seen to enhance iron liberation, by transforming the dissolved Fe(III) to Fe(II), while in the oxidative bioleaching iron liberation was lower. Zinc, copper, indium, gallium and germanium dissolution rates were rather identical with both methods. In reactor experiments, the zinc and copper yields were higher than in flask experiments resulting at best in the leaching yield of 35% and 38% for zinc and copper, respectively. Indium and gallium yields were between 5-8%, but approximately 40% of germanium was leached.

A new technique for measuring the number of single walled carbon nanotubes (SWCNTs) and their concentration in a carbon nanotube layer is developed in this work. It is based on the G peak intensity of the Raman spectrum, together with precise mass and optical absorbance measurements. The dependence of the number of the carbon nanotubes on the phonon scattering intensity is observed. This method opens an opportunity for the quantitative mapping of sp 2 carbon atom distribution in the SWCNT layers with a resolution limited by the focused laser spot size.

Hydrophobins are surface-active proteins that form a hydrophobic, water-repelling film around aerial fungal structures. They have a compact, particle-like structure, in which hydrophilic and hydrophobic regions are spatially, separated. This surface property renders them amphiphilic and is reminiscent of synthetic Janus particles. Here we report surface-specific chiral and nonchiral vibrational sum-frequency generation spectroscopy (VSFG) measurements of hydrophobins adsorbed to their natural place of action, the air-water interface. We observe that hydrophobin molecules undergo a reversible-change in orientation (tilt) at the interface when the pH is varied. We explain this local orientation toggle from the modification of the interprotein interactions and the interaction of hydrophobin with the water solvent, following the pH-induced change of the charge state of particular amino acids.

Orbit following Monte Carlo code (ASCOT) calculations of neutral beam (NB) induced torque, current and heating have been performed for a selected set of plasma scenarios to optimise the neutral beam injection system for the proposed high magnetic field spherical tokamak ST40. It is found that there are strong variations especially in the current drive efficiency and in the toroidal torque depending on the NB alignment and injection energy. The optimal alignments as well as the optimal injection energy depend both on the scenario and whether the current drive or the toroidal torque is to be maximised. Due to the relatively small calculated current drive efficiency (0.05–0.2 MA/MW) we find that for the studied scenarios a relatively central low field side (LFS) deposition below midplane provides the best overall performance still at a tolerable shine through power.

11 pags., 11 figs., 3 tabs., app. -- OCIS codes: (290.1483) BSDF, BRDF, and BTDF; (120.1840) Densitometers, reflectometers; (120.5700) Reflection., The field of spectral radiance factor (SRF) measurements has seen growing interest in recent years. Scale conformity has so far only been established between the national metrology institutes (NMIs) of Germany and the USA. This study aims at a bigger, multilateral scale comparison. For this purpose, a total of six NMIs participated in a scale comparison of goniospectrophotometers based on neutral and colored diffusely reflecting ceramics samples. In addition, two universities, providing a home-built gonioreflectometer and two widely used commercially available color measurement instruments, respectively, were involved. The wavelength range of the scale comparison covers the visible wavelength range from 380 nm to 780 nm. Results indicate systematic issues and that the uncertainty evaluation of the NMIs requires further work; although for the greatest part of the covered spectral range the agreement is good., This work has been realized within the European Metrology Research Program (EMRP) project JRPIND52. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. We thank the European Commission and EURAMET e.V. for financial support.

The sorption of water into the paperboard exposes a container to reversible and irreversible deformations under relative humidity variations. In this study, an elasto-plastic material model is used to demonstrate how through-thickness dry solids content gradients can generate permanent in-plane strains in paperboard. The measurements presented in this paper indicate that in consecutive loading-unloading cycles, the yield stress either remains roughly constant or decreases, and an additional permanent set of strain is obtained even when the maximum tension of repetitions stays constant. Two modified approaches concerning elasto-plastic hardening behavior based on the measurements of this work and the observations of previous studies are introduced. The simulated results exhibit some shared features of the frequently observed shrinkage behavior of paperboard exposed to cyclic relative humidity changes. The results suggest that with the use of a suitable hardening approach, the plastic deformations arising from through-thickness dry solids content gradients may be considered as a time-independent component for simulations of phenomena such as moisture-accelerated creep and release of dried-in stresses. peerReviewed

Ruthenium is a semi-volatile element originating as a fission product in nuclear reactors that can be released in case of a severe nuclear accident. In this work, the impact of atmosphere composition on the transport of ruthenium through the primary circuit was examined. The effects of silver nanoparticles representing aerosols and NO2 gas as a product of air radiolysis were studied. Quantification of ruthenium transported both as gas and aerosol was performed. Chemical composition of ruthenium species was evaluated. The transport of gaseous ruthenium through the facility increased significantly when NO2 gas was fed into the atmosphere. When both silver aerosols and NO2 were fed into the atmosphere, the transport of ruthenium in gaseous and aerosol forms was promoted. It was concluded that the composition of atmosphere in the primary circuit will have a notable effect on the speciation of ruthenium transported into the containment building during a severe accident and thus on the potential radioactive release to the environment.

Copper specimens were exposed to oxygen-deficient artificial groundwater in the presence and absence of micro-organisms enriched from the deep bedrock of the planned nuclear waste repository site at Olkiluoto island on the western coast of Finland. During the exposure periods of 4 and 10 months, the copper specimens were subjected to electrochemical measurements. The biofilm developed on the specimens and the water used in the exposures were subjected to microbiological analyses. Changes in the water chemistry were also determined and surfaces of the copper specimens were characterized with respect to the morphology and composition of the formed corrosion products. The results showed that under biotic conditions, redox of the water and open circuit potential (OCP) of the copper specimens were generally negative and resulted in the build-up of a copper sulphide, Cu2S, layer due to the activity of sulphate-reducing bacteria (SRB) that were included in the system. In the 4-month test, the electrochemical behaviour of the specimens changed during the exposure and alphaproteobactria Rhizobiales were the dominant bacterial group in the biofilm where the highest corrosion rate was observed. In the 10-month test, however, deltaproteobacteria SRB flourished and the initial electrochemical behaviour and the low corrosion rate of the copper were retained until the end of the test period. Under abiotic conditions, the positive water redox potential and specimen OCP correlated with the formation of copper oxide, Cu2O. Furthermore, in the absence of SRB, Cu2O provided slightly inferior protection against corrosion compared to that by Cu2S in the presence of SRB. The obtained results show that the presence of microorganisms may enhance the passivity of copper. In addition, the identification of key microbial species, such as SRB thriving on copper for long time periods, is important for successful prediction of the behaviour of copper.