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Strong light fields have created opportunities to tailor novel functionalities of solids1,2,3,4,5. Floquet–Bloch states can form under periodic driving of electrons and enable exotic quantum phases6,7,8,9,10,11,12,13,14,15. On subcycle timescales, lightwaves can simultaneously drive intraband currents16,17,18,19,20,21,22,23,24,25,26,27,28,29 and interband transitions18,19,30,31, which enable high-harmonic generation16,18,19,21,22,25,28,29,30 and pave the way towards ultrafast electronics. Yet, the interplay of intraband and interband excitations and their relation to Floquet physics have been key open questions as dynamical aspects of Floquet states have remained elusive. Here we provide this link by visualizing the ultrafast build-up of Floquet–Bloch bands with time-resolved and angle-resolved photoemission spectroscopy. We drive surface states on a topological insulator32,33 with mid-infrared fields—strong enough for high-harmonic generation—and directly monitor the transient band structure with subcycle time resolution. Starting with strong intraband currents, we observe how Floquet sidebands emerge within a single optical cycle; intraband acceleration simultaneously proceeds in multiple sidebands until high-energy electrons scatter into bulk states and dissipation destroys the Floquet bands. Quantum non-equilibrium calculations explain the simultaneous occurrence of Floquet states with intraband and interband dynamics. Our joint experiment and theory study provides a direct time-domain view of Floquet physics and explores the fundamental frontiers of ultrafast band-structure engineering.

We here report the results of a mitral valve transcriptome study designed to identify genes and molecular pathways involved in development of myxomatous mitral valve disease (MMVD) in dogs. The study is focused on a cohort of elderly age-matched dogs (n=34, age ~10 years) from a single breed – Cavalier King Charles Spaniels – with a high incidence of MMVD. The cohort comprises 19 dogs (10♀, 9♂) without MMVD, or with early stages of MMVD, and 15 dogs (6♀, 9♂) with congestive heart failure caused by MMVD. I.e. we compare gene expression in breed and age matched groups of dogs, which only differ with respect to severity of disease. We identify 56 genes, which are differentially expressed between the two groups. In this list of genes, we confirm an enrichment of genes related to the TNFβ signaling pathway, extracellular matrix organization, vascular development, and endothelium damage, which also have been identified in previous studies. However, the genes with the greatest difference in expression between the two groups are CNTN3 and MYH1. Both genes encode proteins, which are predicted to have an effect on the contractile activity of myocardial cells, which in turn may have an effect on valvular performance and hemodynamics across the mitral valve. This may result in shear forces with impact on MMVD progression.

Discrete Element Method (DEM) simulations are carried out to investigate the packing structure of the vibrated mono-sized and polydisperse particle assemblies in slender prismatic containers. Quantities like void fraction distributions, coordination number distribution, Voronoi packing fraction distributions were analyzed. DEM simulations show excellent agreement with the experimental data. The transient response of the packing structure during the vibration of mono-sized spheres reveals that the crystallization starts at the walls. The packing structure's crystallinity enhances during vibration, increasing the packing density of the assembly. Vertical vibration is found to be more effective compared to lateral vibration. The packing structure is found to be independent of the container's orientation during the filling process. The influence of the ratio of the container dimensions to mean particle diameter (X/dm) and polydispersity (λ) on the packing structure is analyzed. The results showed that the increase of X/dm ratio or λ, increases the random arrangement of particles.

We study ultrafast population dynamics in the topological surface state of Sb$_2$Te$_3$ in two-dimensional momentum space with time- and angle-resolved two-photon photoemission. Linear polarized mid-infrared pump pulses are used to permit a direct optical excitation across the Dirac point. We show that this resonant excitation is strongly enhanced within the Dirac cone along three of the six $\bar{\Gamma}$-$\bar{M}$ directions and results in a macroscopic photocurrent when the plane of incidence is aligned along a $\bar{\Gamma}$-$\bar{K}$ direction. Our experimental approach makes it possible to disentangle the decay of transiently excited population and photocurent by elastic and inelastic electron scattering within the full Dirac cone in unprecedented detail. This is utilized to show that doping of Sb$_2$Te$_3$ by vanadium atoms strongly enhances inelastic electron scattering to lower energies, but only scarcely affects elastic scattering around the Dirac cone., Comment: 9 pages, 4 figures

In diesem Artikel soll die Relevanz seltener Erkrankungen mit ihren schmerztherapeutischen Besonderheiten verdeutlicht werden. Dazu werden vier seltene Erkrankungen, (Hamophilie, Morbus Fabry, Dermatomyositis und fazioskapulohumerale Muskeldystrophie [FSHD]) exemplarisch vorgestellt und grundlegende Aspekte der jeweils anzuwendenden Schmerztherapien erlautert. Die Erkrankungen wurden so gewahlt, dass beispielhaft eine Schmerztherapie entsprechend einem adaptierten WHO-Stufenschema (Hamophilie), eine sehr komplexe, aber relativ gut etablierte Schmerztherapie (M. Fabry) und zwei weniger etablierte Schmerztherapien nach sehr individuellen Schemata vorgestellt werden (Dermatomyositis, FSHD).

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Lightwave electronics has pushed the control of condensed matter to unprecedented time scales. By harnessing the carrier wave of intense light pulses as an alternating voltage [1] – [12] , electrons can be driven faster than a cycle of light, opening up a fascinating quantum world full of promise for future quantum technologies.

The ability to detect and selectively identify trace amounts of metal ions is of major importance for drinking water identification and biological studies. Herein, we report a series of water-soluble Schiff-base ligands capable of being fluorescent and colorimetric sensors for metal ions. Upon coordination of the metal ion to the ligand, quenching of fluorescence is observed, typically in a 1:1 ratio. The selectivity of metal ions Cu2+, Ni2+, Cr3+, and Co2+ is exhibited via fluorescence quenching accompanied by colorimetric changes, whereas that of Ag+ and Co2+ is observed through colorimetric changes alone. Additionally, pH sensing studies were performed for the potential use of these ligands in biological applications.

The science guiding the EUREC4A campaign and its measurements is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC4A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC4A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement.

How fast is the charge transfer between two layers of transition metal dichalcogenides and where does it take place in momentum space? Two-photon photoemission using high-harmonic probe pulses can answer this question, as the authors demonstrate here for the topmost layers of MoS${}_{2}$. By tuning pump pulses below the topmost-layer gap, they excite electrons in deeper layers and probe only the topmost layer. GW-based tight-binding calculations support the experimental findings and explain why the electron transfer takes place at $\overline{\mathrm{\ensuremath{\Sigma}}}$.

In this article we address the relevance of rare diseases and their peculiarities with respect to pain therapy. Towards this end, four rare diseases (hemophilia, Morbus Fabry, dermatomyositis, and facioscapulohumeral dystrophy (FSHD)) will be presented and fundamental aspects of their pain therapies described. The diseases were chosen to showcase a pain therapy based on the WHO-step-by-step plan (hemophilia), a complex but established pain therapy (M. Fabry), and two less well established, individually adapted pain therapies (dermatomyositis, FSHD).

Myoclonus is a sudden and brief involuntary muscle contraction presenting with jerk-like movements that can occasionally involve the trunk muscles or the diaphragm as in the case of spinal myoclonus1. We here present an unusual case with unilateral diaphragmatic myoclonus owing to electrode dislocation of an implantable cardioverter defibrillator.

Basic physics places limits on the mechanics involved in shaking a baby. Fundamental definitions and practical limitations are used to compare shaking with car crashes and low-level falls. First-order mathematical considerations applied to a 6-month-old infant determine an angular velocity limit for head rotation around 75 rad/s and maximum angular acceleration less than 1600 rad/s2 without impact. By comparison, results from a low-level fall of 0.76 m (30 inches) yield values of 83 rad/s and 13,000 rad/s2 in a practical worst-case scenario.

As conventional electronics approaches its ultimate limits, novel concepts of fast quantum control have been sought after. Lightwave electronics – the foundation of attosecond science – has opened a new arena by utilizing the oscillating carrier wave of intense light pulses to control electrons faster than a cycle of light. We employ atomically strong terahertz electromagnetic pulses to accelerate electrons through the entire Brillouin zone of solids, drive quasiparticle collisions, and generate high-harmonic radiation as well as high-order sidebands. The unique band structures of topological insulators allow for all-ballistic and quasi-relativistic acceleration of Dirac quasiparticles over distances as large as 0.5 μm. In monolayers of transition metal dichalcogenides, we switch the electrons’ valley pseudospin, opening the door to subcycle valleytronics. Finally, we show that lightwave electronics can be combined with ultimate atomic spatial resolution in state-selective ultrafast scanning tunneling microscopy.

Utilizing the carrier wave of terahertz pulses, we drive all-ballistic Dirac currents on topological insulators and control the valley pseudospin in monolayer WSe2. Antenna-enhanced single-cycle terahertz pulses ballistically switch the antiferromagnetic spin order in TmFeO3.

We observe terahertz-driven all-ballistic Dirac currents on the topological insulator Bi2Te3 and subcycle switching of the valley pseudospin in monolayer WSe2. The results encourage practical electronic and valleytronic devices operating at optical clock rates.

Harnessing the carrier wave of light as an alternating-current bias may enable electronics at optical clock rates1. Lightwave-driven currents have been assumed to be essential for high-harmonic generation in solids2-6, charge transport in nanostructures7,8, attosecond-streaking experiments9-16 and atomic-resolution ultrafast microscopy17,18. However, in conventional semiconductors and dielectrics, the finite effective mass and ultrafast scattering of electrons limit their ballistic excursion and velocity. The Dirac-like, quasi-relativistic band structure of topological insulators19-29 may allow these constraints to be lifted and may thus open a new era of lightwave electronics. To understand the associated, complex motion of electrons, comprehensive experimental access to carrier-wave-driven currents is crucial. Here we report angle-resolved photoemission spectroscopy with subcycle time resolution that enables us to observe directly how the carrier wave of a terahertz light pulse accelerates Dirac fermions in the band structure of the topological surface state of Bi2Te3. While terahertz streaking of photoemitted electrons traces the electromagnetic field at the surface, the acceleration of Dirac states leads to a strong redistribution of electrons in momentum space. The inertia-free surface currents are protected by spin-momentum locking and reach peak densities as large as two amps per centimetre, with ballistic mean free paths of several hundreds of nanometres, opening up a realistic parameter space for all-coherent lightwave-driven electronic devices. Furthermore, our subcycle-resolution analysis of the band structure may greatly improve our understanding of electron dynamics and strong-field interaction in solids.

The Dirac-cone surface states of topological insulators are characterized by a chiral spin texture in k-space with the electron spin locked to its parallel momentum. Mid-infrared pump pulses can induce spin-polarized photocurrents in such a topological surface state by optical transitions between the occupied and unoccupied part of the Dirac cone. We monitor the ultrafast dynamics of the corresponding asymmetric electron population in momentum space directly by time- and angle-resolved two-photon photoemission (2PPE). The elastic scattering times of 2.5 ps deduced for Sb2Te3 corresponds to a mean-fee path of 0.75 μm in real space.

We present energy-momentum mapping of surface Dirac photocurrent in the topological insulator Sb$_2$Te$_3$ by means of time- and angle-resolved two-photon photoemission spectroscopy combined with polarization-variable mid-infrared pulse laser. It is demonstrated that the direct optical transition from the occupied to the unoccupied part of the surface Dirac-cone permits the linear and circular photogalvanic effect which thereby enables us to coherently control the surface electric-current by laser polarization. Moreover, the surface current mapping directly visualizes ultrafast current dynamics in the Dirac cone in the time domain. We unravel the ultrafast intraband relaxation dynamics of the inelastic scattering and momentum scattering separately. Our observations pave the pathway for coherent optical control over surface Dirac electrons in topological insulators.

Quantum anomalous Hall effect (QAHE) is a key phenomenon for low power-consumption device applications owing to its dissipationless spin-polarized and quantized current in the absence of an external magnetic field. However, the recorded working temperature of the QAHE is still very low. Here we systematically investigate the magnetic dopants induced modifications from the view points of magnetic, structural and electronic properties and the ultrafast carrier dynamics in a series of V-doped Sb2Te3 samples of composition Sb2−x V x Te3 with x = 0, 0.015 and 0.03. Element specific x-ray magnetic circular dichroism signifies that the ferromagnetism of V-doped Sb2Te3 is governed by the p–d hybridization between the host carrier and the magnetic dopant. Time- and angle-resolved photoemission spectroscopy excited with mid-infrared pulses has revealed that the V impurity induced states underlying the topological surface state (TSS) add scattering channels that significantly shorten the duration of transient surface electrons down to the 100 fs scale. This is in a sharp contrast to the prolonged duration reported for pristine samples though the TSS is located inside the bulk energy gap of the host in either magnetic or non-magnetic cases. It implies the presence of a mobility gap in the bulk energy gap region of the host material that would work toward the robust QAHE. Our findings shed light on the material design for low-energy-consuming device applications.

We combine tunable midinfrared (mid-IR) pump pulses with time- and angle-resolved two-photon photoemission to study ultrafast photoexcitation of the topological surface state (TSS) of Sb_{2}Te_{3}. It is revealed that mid-IR pulses permit a direct excitation from the occupied to the unoccupied part of the TSS across the Dirac point. The novel optical coupling induces asymmetric transient populations of the TSS at ±k_{∥}, which reflects a macroscopic photoexcited electric surface current. By observing the decay of the asymmetric population, we directly investigate the dynamics of the long-lived photocurrent in the time domain. Our discovery promises important advantages of photoexcitation by mid-IR pulses for spintronic applications.

This article reviews the research on ceramic tritium breeding materials and the development of these materials, which aims at providing the tritium required for the deuterium–tritium fuel cycle in magnetic fusion reactors. In particular, the performance of various oxides of lithium is discussed. Currently, much of the ceramic breeder research and development is focused on lithium orthosilicate and metatitanate systems in the form of pebble beds. This chapter reviews design requirements, manufacturing routes, pebble and pebble-bed thermomechanics, tritium production and release properties, neutron-irradiation behavior, chemistry, and modeling. Ongoing work is summarized and the outlook for further work, including test programs in International Thermonuclear Experimental Reactor (ITER), is provided.

We report on the direct mapping of electron transfer in the momentum space of bulk MoS$_2$ by means of time- and angle-resolved two-photon photoemission with a high-harmonic probe. For this purpose, we have combined a high-repetition rate high-harmonic source with tunable femtosecond pump pulses and a 3D ($k_x, k_y, E$) electron spectrometer. We show that optical excitation slightly above the A exciton resonance results in an immediate occupation of the conduction band at $\overline{K}$ followed by an ultrafast transfer ($< 50$~fs) to the conduction band minimum at $\overline{\Sigma}$. Both signals, at $\overline{K}$ and $\overline{\Sigma}$, do not vanish over the observed period of 400~fs. The technique described here enables direct access to the charge transfer dynamics in $k$-space and allows the study of decay times and decay channels in various systems with dependence on the excess energy or helicity of the excitation., Comment: 11 pages, 4 figures

The wide-angle light scattering (WALS) approach has been utilized for the measurement of soot aggregate sizes (radii of gyration) in flames on a single-shot basis. Key elements are a pulsed laser and an ellipsoidal mirror, which images the light scattered within a plane onto an intensified CCD camera, thus allowing for an instantaneous acquisition of a full scattering diagram with high resolution. Results for a laminar premixed flame exhibit good agreement with averaged data and demonstrate the feasibility of the method. The applicability of the technique to unsteady combustion processes is demonstrated by measuring aggregate sizes in a weakly turbulent jet-diffusion flame. In both cases light scattering results are verified by data obtained from electron microscopy analysis of sampled soot.

The European Space Research and Technology Center ESTEC, ESA’s premises in Noordwijk, The Netherlands, has a long lasting cooperation with the ZARM-FAB (Centre of Applied Space Technology and Microgravity—Drop Tower Operation and Service Company) in Bremen on the utilization of the Drop Tower for ground-based microgravity research and space hardware development studies. During the period January 2000 to December 2011 ESA will have procured in total some 840 drops addressing a variety of scientific and technological disciplines. The experiments are usually carried out in campaigns of 15 to 20 drops each, with an annual average of about 5 campaigns. The cooperation agreement between ESA and the ZARM-FAB includes experiment preparation advice by ZARM’s experts, the integration of the hardware into the drop capsule, dedicated safety reviews, the execution of the drop or catapult experiments, the post-flight payload de-integration as well as the handover of acquired data to the experimenters. The experiment hardware itself is provided by the scientists or has to be procured from sources outside of ESA’s drop tower utilization contract. ESA appreciates the cooperation of the ZARM-FAB in Bremen whose drop- and catapult facility provides excellent microgravity quality, is operated by a highly competent, flexible and extremely supportive expert team, allows campaign integration at relatively short notice throughout the entire year, offers real-time experiment operations and immediately after each drop delivers experiment results and provides on-site hardware modification possibilities.

The current study investigated the predictive validity of several popular risk-related assessment instruments with respect to seclusion. The Hare Psychopathy Checklist-Revised (PCL-R; Hare, 2003), Version 2 of the HCR-20 (HCR-20; Webster, Douglas, Eaves, & Hart, 1997), the Violence Risk Appraisal Guide (VRAG; Harris, Rice, & Quinsey, 1998), and the Level of Service Inventory-Revised (LSI-R; Andrews & Bonta, 1995) were coded from institutional files for a sample of 130 patients from a medium-secure forensic inpatient unit. Seclusion was indexed in terms of total number of seclusions during a period of two years and total time spent in seclusion. ROC analyses indicated that all instruments had small to moderate and significant predictive validity with respect to frequency of seclusion, but were less strongly predictive of duration of seclusion. Overall, Factor 2 of the PCL-R was the best predictor of seclusion. Implications for practice and the necessity for future and local research are discussed.

In HCPB blankets, pebble beds are composed of nearly spherical particles in the state of random closed packing. The packing structure is important to understand responses of pebble beds, e.g., mechanical stresses and effective thermal conductivity. In this paper, an algorithm for random close packing of polydisperse particles is presented which can be used for arbitrary pebble bed containing geometries. The microstructure of a packed bed in both the bulk and near-wall regions can be determined. Computer-generated samples are compared to recent X-ray tomography results of non-compressed pebble beds, including the packing factors and coordination number. Moreover, initial configurations obtained by this method can be used in discrete element simulations of random configurations of pebbles to investigate the overall behaviour of pebble beds under fusion-relevant conditions.

An analytical tool to monitor the arrangement of pebbles in a pebble bed as well as the morphology of gas bubbles in as fabricated and neutron irradiated beryllium pebbles is presented. The context of this study is the Helium Cooled Pebble Bed (HPCB) blanket design for the forthcoming generation of fusion reactors. The thermal-mechanical behavior of pebble beds is a basic issue for the HPCB. It depends strongly on the configuration of the pebbles in the bed, and in particular on the number of contacts between pebbles, and between pebbles and the blanket walls. The related contact surfaces play also a major role. The knowledge on the inner structure of the pebbles is required since during the life cycle of a power reactor helium and tritium bubbles are produced inside the beryllium pebbles and the tritium build-up can be in excess of several kilograms, being thereby a key safety issue. All the non-destructive analyses are based on 3D computer aided microtomography using a very powerful synchrotron radiation x-ray source with high spatial resolution. The data analysis relies on a topological operator called filtered medial line applied to the entire data volumes and the related graph representation. By this technique the number of contacts between the pebbles in pebble packs and their angular distribution are obtained, as well as the corresponding contact surfaces. The evaluation of bubble sizes and densities in single pebbles, the assessment of the pore channel network topology, the 3D reconstruction of the fraction of interconnected bubble porosity, and the open-to-closed-porosity ratio are among the most interesting findings.

Micronutrients play an important role in function and health maintenance for the eye. Especially lutein, zeaxanthin and omega-3 fatty acids perform remarkable functions: lutein together with zeaxanthin forms the macular pigment, these carotenoids filter out the damaging blue light component from the sunlight as well as the ultraviolet light which leads to improved contrast sensitivity and less problems with screen glare. Furthermore, the macular pigment has antioxidant and anti-inflammatory effects. The omega-3 fatty acids also possess anti-inflammatory effects and, when converted into neuroprotectin, they protect against oxidative induced apoptosis in the retina. They are also responsible for the fluidity and supply to the photoreceptor membrane. These properties are important for the prevention and treatment of degenerative eye diseases like age-related macular degeneration. However, older people are often not sufficiently supplied of micronutrients in their diet. Because the supply of nutrients can hardly be achieved by dietary change, the additional intake in the form of food supplements is useful in this age group. Scientific studies have shown the positive effects of supplementation with micronutrients such as lutein/zeaxanthin, vitamin C, vitamin E, zinc and omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid (DHA and EPA). Currently available nutritional products are based in part on the ingredients of the ARED study (Age Related Eye Disease Study). According to more recent studies formulations containing lutein and omega-3 fatty acids in physiologically meaningful doses without additional beta-carotene should be preferred. 10 to 20 mg of lutein and zeaxanthin represent a safe daily dose Regarding to the context above, beta-carotene in high doses plays a minor role to the eye and is especially critical for the health of smokers. This paper summarises the functions of the presented micronutrients in the eye and can assist ophthalmologists in advising their patients.

A novel set-up for the experimental determination of aggregate morphology in combustion processes based on elastic light scattering has been designed and realized. A key feature of this wide-angle light scattering (WALS) approach is an ellipsoidal mirror which is used to collect scattered light over a wide angular range of about 10–170°. The set-up employs a cw solid-state laser as light source and an intensified CCD-camera as detector. By means of the mirror the scattered light is imaged onto the detector allowing for a simultaneous acquisition of a full scattering diagram with a high angular resolution of about 0.6°. To demonstrate the performance of the approach, measurements for various sooting flames produced by premixed combustion in a flat flame burner were carried out, where the burner was operated with different equivalence ratios and fuels. It is shown that radii of gyration of soot particles may efficiently be obtained from an analysis of the scattering diagrams.

The combination of laser-induced incandescence and elastic light scattering has been further developed to allow for a quantitative two-dimensional determination of characteristic properties of soot aggregates, namely radius of gyration R g and number N p of primary particles per aggregate. In demonstrating the principle of the method, we have in a first approach approximated the particle ensemble as monodisperse and used a structure factor with an exponential cut-off function. Nonetheless, experiments performed on a laminar premixed ethene flame demonstrate basically good agreement with observations from literature and data from electron microscopy on thermophoretically obtained samples.

We combine tunable midinfrared (mid-IR) pump pulses with time- and angle-resolved two-photon photoemission to study ultrafast photoexcitation of the topological surface state (TSS) of Sb_{2}Te_{3}. It is revealed that mid-IR pulses permit a direct excitation from the occupied to the unoccupied part of the TSS across the Dirac point. The novel optical coupling induces asymmetric transient populations of the TSS at ±k_{∥}, which reflects a macroscopic photoexcited electric surface current. By observing the decay of the asymmetric population, we directly investigate the dynamics of the long-lived photocurrent in the time domain. Our discovery promises important advantages of photoexcitation by mid-IR pulses for spintronic applications.

Prions induce lethal neurodegeneration and consist of PrPSc, an aggregated conformer of the cellular prion protein PrPC. Antibody-derived ligands to the globular domain of PrPC (collectively termed GDL) are also neurotoxic. Here we show that GDL and prion infections activate the same pathways. Firstly, both GDL and prion infection of cerebellar organotypic cultured slices (COCS) induced the production of reactive oxygen species (ROS). Accordingly, ROS scavenging, which counteracts GDL toxicity in vitro and in vivo, prolonged the lifespan of prion-infected mice and protected prion-infected COCS from neurodegeneration. Instead, neither glutamate receptor antagonists nor inhibitors of endoplasmic reticulum calcium channels abolished neurotoxicity in either model. Secondly, antibodies against the flexible tail (FT) of PrPC reduced neurotoxicity in both GDL-exposed and prion-infected COCS, suggesting that the FT executes toxicity in both paradigms. Thirdly, the PERK pathway of the unfolded protein response was activated in both models. Finally, 80% of transcriptionally downregulated genes overlapped between prion-infected and GDL-treated COCS. We conclude that GDL mimic the interaction of PrPSc with PrPC, thereby triggering the downstream events characteristic of prion infection. © 2015 Herrmann et al.

Uncertainties in modeling heat conduction in connection with the application of laser-induced incandescence (LII) to primary particle sizing are discussed. Comparing two models widely used in this context, namely those of Fuchs [(1963). On the stationary charge distribution on aerosol particles in a bipolar ionic atmosphere. Pure and Applied Geophysics 56, 185–193] and McCoy/Cha [(1974). Transport phenomena in the rarefied gas transition regime. Chemical Engineering Science 29, 381–388], it is demonstrated that arising differences may be accounted for by the choice of a proper “effective” thermal accommodation coefficient α eff . In experiments on a large number of carbon blacks an overally good agreement between LII results and specified values for particle sizes based on electron-microscopy (EM) is obtained with a choice of α eff = 0.25 (based on the McCoy/Cha-model). As aggregate size is expected to influence heat transfer from primary particles, the experimental data are analyzed by a model for an effective heat transfer surface of fractal aggregates. Based on values for the average number of primary particles per aggregate as derived from photocentrifuge measurements the data yield an extrapolated value for the physical accommodation coefficient for isolated particles of α 1 = 0.43 .

In the helium-cooled lithium lead (HCLL) blanket, liquid metal circulation is primarily required for tritium removal. Larger flow rates are desirable in order to keep the tritium permeation losses low. Because of electrically conducting structures, pressure drop becomes already large at small flow rates. Moreover, tritium permeation depends sensitively on velocity distributions in the ducts; MHD issues are, therefore, also relevant for the HCLL. In the paper, first the MHD specific flow features of the HCLL blanket are outlined and the status of pressure drop assessments is reported. Then, results of analyses are presented for velocity distributions influenced by flow coupling effect and thermal convection flows.

Thermal stresses occurring during operation of helium-cooled pebble bed blankets will cause pebble deformations which increase the pebble bed thermal conductivity due to an increase of contact surfaces between the pebbles. The dependence of the thermal conductivity from pebble bed strain is generally determined in test set-ups where only global quantities (uniaxial stress, strain and temperature) are measured. For the understanding of heat transfer mechanisms, the knowledge of the topology of the pebble beds (number of pebble contacts with other pebbles or walls, corresponding contact zones, angular distribution of contacts on the pebbles) is of great interest. Experiments were performed where, first, pebble beds were uniaxially compressed to different strain levels. For better measurement accuracy, spherical 3.5 or 5 mm aluminium pebbles were used instead of blanket relevant 1 mm beryllium pebbles. Then, the topological quantities were determined by two methods: A) In the European Synchrotron Radiation Facility (ESRF) Grenoble, a special microtomography experimental set-up was used allowing the computer aided reconstruction of 3D images of pebbles within the pebble beds. By post-processing the data, both radial and axial void fraction distributions were determined as well as the topological quantities. B) In the Forschungszentrum Karlsruhe (FZK), the pebbles were chemically coloured in the compressed state in order to increase the optical contrast. Optical microscopy was then used to determine pebble contact numbers and contact surfaces. Results from both methods complement one another very well due to specific experimental limitations of both techniques.