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Objective Cochlear implants (CIs) provide access to the auditory world for deaf individuals. We investigated whether CIs enforce attentional alterations of auditory cortical processing in post-lingually deafened CI users compared to normal-hearing (NH) controls. Methods Event-related potentials (ERPs) were recorded in 40 post-lingually deafened CI users and in a group of 40 NH controls using an auditory three-stimulus oddball task, which included frequent standard tones (Standards) and infrequent deviant tones (Targets), as well as infrequently occurring unique sounds (Novels). Participants were exposed twice to the three-stimulus oddball task, once under the instruction to ignore the stimuli (ignore condition), and once under the instruction to respond to infrequently occurring deviant tones (attend condition). Results The allocation of attention to auditory oddball stimuli exerted stronger effects on N1 amplitudes at posterior electrodes in response to Standards and to Targets in CI users than in NH controls. Other ERP amplitudes showed similar attentional modulations in both groups (P2 in response to Standards, N2 in response to Targets and Novels, P3 in response to Targets). We also observed a statistical trend for an attenuated attentional modulation of Novelty P3 amplitudes in CI users compared to NH controls. Conclusions ERP correlates of enhanced CI-mediated auditory attention are confined to the latency range of the auditory N1, suggesting that enhanced attentional modulation during auditory stimulus discrimination occurs primarily in associative auditory cortices of CI users. Significance The present ERP data support the hypothesis of attentional alterations of auditory cortical processing in CI users. These findings may be of clinical relevance for the CI rehabilitation.

Pure phase NbFeSb1-xSnx (where x = 0, 0.04, 0.08, 0.12, 0.16) half-Heusler samples were prepared by direct mechanical alloying followed by spark plasma sintering. The results showed that the substitution of Sb by Sn can effectively enhance the peak figure of merit (ZT) to 0.55 at 923 K in NbFeSb0.88Sn0.12 through optimized carrier concentration. To further reduce the lattice thermal conductivity (κL), we substituted Nb by Hf to enhance the point defect scattering of phonon transport. A maximum reduction of ~80% in κL was observed in Nb0.8Hf0.2FeSb0.88Sn0.12 when compared to undoped NbFeSb at 573 K. We realized a minimum κL of ~2.96 W m−1 K−1 at 673 K and a peak ZT of ~0.82 at 973 K for Nb0.88Hf0.12FeSb0.88Sn0.12.

We present thermal expansion studies on single-crystalline LaFe 1 - x Co x AsO with doping levels of x = 0, 0.026, and 0.034, and on BaFe 2 As 2 . Anomalies in the thermal expansion coefficient α enable reading off the structural and magnetic transition temperatures T S and T N . The evolution of the orthorhombic distortion at T S is illustrated by length changes of the a- and b-axes and the experimentally determined orthorhombicity δ . The results are compared to BaFe2As2. Finally, the electronic phase diagram is discussed.

The ternary iron arsenide compound BaFe2As2 exhibits a structural phase transition from tetragonal to orthorhombic at a temperature of about 140 K. The twin lamellae arising below this transition temperature were studied in undoped single crystalline bulk and epitaxial thin film samples using electron backscatter diffraction in a scanning electron microscope equipped with a helium cryostat. Applying this technique on bulk single crystals a characteristic twin lamella size in the range of 0.1 μm up to a few μm was observed. In contrast, in epitaxially strained thin films the phase transition is not observed at temperatures above 19 K.

Organophosphorus compounds have a wide range of reactivity depending on the coordination and oxidation state of the P atom. Due to their toxicity, certain organophosphonates are used as pesticides, herbicides, and, notoriously, as chemical nerve agents. The organophosphonate decomposition mechanism depends strongly on the substrate material, which motivates careful analysis of a range of potential materials for decontamination and sensing applications. Here, we present a study of the decomposition of dimethyl methylphosphonate (DMMP), a simulant molecule for the nerve agent sarin, on polycrystalline cuprous oxide surfaces (Cu2O). We use ambient pressure X-ray photoelectron spectroscopy (APXPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to monitor the pressure-dependent surface chemistry during exposure to DMMP vapor. At room temperature, we observe extensive degradation of DMMP, which includes the formation of reduced P products on the sample surface. We identify five unique P-containing species in the P 2p APXPS spectra, including atomic P and a surface-bound phosphinate [O PH(OCH3)O Cu]. We propose a DMMP decomposition pathway whereby accumulation of this phosphinate species leads to an autocatalytic reaction on the Cu2O surface which yields reduced P species. After DMMP exposure, heating the Cu2O sample to 265 °C leads to complete removal of all carbonaceous species and accumulation of a phosphate layer with stoichiometry similar to P2O5. These results introduce a new mechanism of room-temperature DMMP decomposition on metal oxides, which could be leveraged for the design of tailored metal oxide materials for catalyzing organophosphonate decomposition.

The laser-diode-heated floating-zone (LDFZ) is a new variant of the floating-zone (FZ) technique where the molten-zone is established using a set of horizontal laser beams. Unlike a conventional mirror-type FZ, the non-divergent property of the laser beam in LDFZ allows for the growth of high melting temperature refractory materials comprising volatile components. The compound ErVO3 not only has a high melting temperature (∼2100 °C), it also contains volatile V2O3 as one of the components. We show here that large (cm-size) and high-quality crystals of ErVO3 can be obtained with relative ease using the LDFZ technique. In contrast, using the conventional FZ technique, an excessive evaporation of V2O3 from the molten-zone and the feed-rod led to discontinuation of growth within a short time; and the resulting boule, about 2 cm long, was essentially polycrystalline with tiny (less than 1 mm in size) crystals embedded in it. The high-quality of the LDFZ-grown crystal boule is inferred using optical and electron microscopies, Laue backscattering and neutron diffraction techniques. Magnetic susceptibility, neutron diffraction and specific heat measurements on the grown crystal confirmed the presence of orbital ordering at TOO = 195 K, V3+ spin ordering at TM1 = 110 K, simultaneous spin and orbital ordering at TM2 = 58 K, and the long-range ordering of the Er moments near 2.5 K. Our work establishes a relatively straightforward method of growing large crystals of the RVO3 family of compounds. The method can be extended to other high melting temperature refractory materials with volatile components.

We investigated the physicochemical surface properties of different highly aligned nitrogen-doped multi-walled carbon nanotube (N-MWCNT) carpets, synthesized using toluene/pyrazine, toluene/benzylamine and acetonitrile via a sublimation-based chemical vapor deposition (SCVD) method at 760{\deg}C. The surfaces of the N-MWCNT carpets synthesized using toluene/pyrazine and toluene/benzylamine were very hydrophobic. In contrast, we observed a complete wetting of the N-MWCNT carpets synthesized using acetonitrile. The difference in the wetting behavior of these N-MWCNT carpets is the main focus in this study and was not investigated before. Here, we show that not only the presence or concentration of nitrogen inside the carbon lattice, but especially it's kind of incorporation have an important influence on the surface polarity., Comment: preprint, 19 pages, 4 Figures

The length of multi-walled carbon nanotubes (MWCNT) has a particular relevance for a wide range of application. To that end, in an aerosol assisted chemical vapour deposition process MWCNT carpets with different heights were synthesized on an oxidized silicon substrate by using ferrocene as Fe-catalyst precursor and some hydrocarbons with different hybridization state. By variation of the synthesis temperature from 600 °C up to 900 °C, for every used hydrocarbon different carpet heights were measured depending on the temperature. Cyclohexane generated the highest MWCNT carpets and for all carbon precursor the maximum carpet height was measured at 850 °C. To elucidate this, the thermal decomposition of the used hydrocarbons was discussed and the corresponding main decomposition products methane, ethene and benzene were identified. Subsequently, these substances were directly used in a second chemical vapour deposition equipment to simulate the growth mechanism by the intermediate carbon precursors. It was found, that with comparable content of carbon in the gas phase, ethene is much higher efficient for growing high MWCNT carpets than methane. Moreover, benzene was figured out to be also an adequate carbon precursor under specific gas phase conditions, explaining the carpet heights when using toluene and xylene.

Co2CrAl is predicted as a promising candidate for half-metallic ferromagnetism. Unfortunately, synthesis of the stoichiometric composition is a challenge as the samples prepared so far using various techniques suffer from formation of secondary phases and consequently anomalous physical properties. Off-stoichiometric compounds have been explored as a possible approach to avoid the secondary phase precipitation. The Co 2 Cr 0.8 Al 1.2 , Co 2 Cr 0.6 Al 1.4 and Co 2 Cr 0.4 Al 1.6 compositions were synthesized using Floating Zone (FZ) technique as they melt incongruently. The secondary phase fraction was reduced as Cr was partially substituted by Al. FZ-grown Co 2 Cr 0.4 Al 1.6 was obtained as a single phase, signifying that the composition is out of the two-phase region. Furthermore, combining the data with an earlier work on annealing of spinodally decomposed samples, valuable insight into the extent of immiscibility was obtained.

We have studied the superconducting spin-valve effect in a F1/F2/S heterostructure containing a Heusler alloy layer standing for an F2 layer. The Heusler alloy layer was grown at the substrate temperature T sub = 300 K . According to our previous data in such preparation conditions this layer is a weak ferromagnet. For the samples with the Heusler layer thickness d Heusler = 1 and 4 nm the full switching between the normal and superconducting states is realized with the dominant aid of the long-range triplet component of the superconducting pair condensate which occurs at the perpendicular mutual orientation of magnetizations.

Annealing and functionalization of carbon nanotube yarns (CNYs) is a prospective way of increasing the electrical conductivity of this material. We show a novel way, the simultaneous annealing and instant coating of the CNY by its resistance-heating in atmospheres of hydrocarbons. This method is capable to preserve the lightweight properties of CNYs and increase the electrical conductivity. It could be raised by a factor of 2 through carbon deposition onto the yarns and the carbon nanotubes (CNTs) inside the yarn structure. By resistance-heating over a multistep process the conductivity could be even increased by a factor of 2.2. Comparison of annealing under atmosphere of different hydrocarbons and at different temperatures reveals the influence of resistance-heating on the structure of CNY.