Extracting long-lasting performance from electronic devices and improving their reliability through effective heat management requires good thermal conductors. Taking both three- and four-phonon ...scattering as well as electron-phonon and isotope scattering into account, we predict that semimetallic θ-phase tantalum nitride (θ-TaN) has an ultrahigh thermal conductivity (κ), of 995 and 820 W m^{-1} K^{-1} at room temperature along the a and c axes, respectively. Phonons are found to be the main heat carriers, and the high κ hinges on a particular combination of factors: weak electron-phonon scattering, low isotopic mass disorder, and a large frequency gap between acoustic and optical phonon modes that, together with acoustic bunching, impedes three-phonon processes. On the other hand, four-phonon scattering is found to be significant. This study provides new insight into heat conduction in semimetallic solids and extends the search for high-κ materials into the realms of semimetals and noncubic crystal structures.
The effect of substituting linkers with electron-donating moieties for part of the conventional ones on the melting and glass transition behaviours of ZIF-62 was investigated by calorimetry and X-ray ...diffraction. Specifically, substituting 5,6-dimethylbenzimidazole for benzimidazole in ZIF-62 increases both
T
m
and
T
g
. The structural origin of this effect was explained.
The effect of substituting linkers with electron-donating moieties for part of the conventional ones on the melting and glass transition behaviours of ZIF-62 was investigated by calorimetry and X-ray diffraction.
Differences in fundamental frequency (F0) or pitch between competing voices facilitate our ability to segregate a target voice from interferers, thereby enhancing speech intelligibility. Although ...lower-numbered harmonics elicit a stronger and more accurate pitch sensation than higher-numbered harmonics, it is unclear whether the stronger pitch leads to an increased benefit of pitch differences when segregating competing talkers. To answer this question, sentence recognition was tested in young normal-hearing listeners in the presence of a single competing talker. The stimuli were presented in a broadband condition or were highpass or lowpass filtered to manipulate the pitch accuracy of the voicing, while maintaining roughly equal speech intelligibility in the highpass and lowpass regions. Performance was measured with average F0 differences (ΔF0) between the target and single-talker masker of 0, 2, and 4 semitones. Pitch discrimination abilities were also measured to confirm that the lowpass-filtered stimuli elicited greater pitch accuracy than the highpass-filtered stimuli. No interaction was found between filter type and ΔF0 in the sentence recognition task, suggesting little or no effect of harmonic rank or pitch accuracy on the ability to use F0 to segregate natural voices, even when the average ΔF0 is relatively small. The results suggest that listeners are able to obtain some benefit of pitch differences between competing voices, even when pitch salience and accuracy is low.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize ...the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2–7 m, while providing data at sub-mm to mm scales. We report on SuperCam’s science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data.
The mechanisms causing the reduction in lattice thermal conductivity in highly P- and B-doped Si are looked into in detail. Scattering rates of phonons by point defects, as well as by electrons, are ...calculated from first principles. Lattice thermal conductivities are calculated considering these scattering mechanisms both individually and together. It is found that at low carrier concentrations and temperatures phonon scattering by electrons is dominant and can reproduce the experimental thermal conductivity reduction. However, at higher doping concentrations the scattering rates of phonons by point defects dominate the ones by electrons except for the lowest phonon frequencies. Consequently, phonon scattering by point defects contributes substantially to the thermal conductivity reduction in Si at defect concentrations above 10
19
cm
−3
even at room temperature. Only when, phonon scattering by both point defects and electrons are taken into account, excellent agreement is obtained with the experimental values at all temperatures.
Successful prediction of thermal conductivity of highly-doped Si, revealing the importance of phonon scattering by electrons as well as point defects.
Knowledge of the effect of plant secondary compounds (PSCs) on belowground interactions in the more diffuse community of species living outside the rhizosphere is sparse compared with what we know ...about how PSCs affect aboveground interactions. We illustrate here that PSCs from foliar tissue, root exudates, and leaf litter effectively influence such belowground plant–plant, plant–microorganism, and plant–soil invertebrate interactions. Climatic factors can induce PSC production and select for different plant chemical types. Therefore, climate change can alter both quantitative and qualitative PSC production, and how these compounds move in the soil. This can change the soil chemical environment, with cascading effects on both the ecology and evolution of belowground species interactions and, ultimately, soil functioning.
Plants produce a high diversity of secondary compounds that are released to their surroundings.The role of PSCs on aboveground interactions has been well studied, but less is known about the role of PSCs in mediating and determining the outcome of belowground interactions, especially interactions beyond the rhizosphere.PSCs enter the soil directly by excretion from belowground plant organs or indirectly by washing from the canopy and leaching from litter.Leaching of PSCs creates a heterogeneous soil chemical environment and mediates plant–plant interactions, plant–microbiome associations, and plant–soil invertebrate relationships. This also affects and shapes the diffuse community of species living in soil further away from the rhizosphere.Climate change can substantially alter the quantitative and qualitative production of PSCs released to the soil, which may change belowground species interactions and affect species composition, richness, and, ultimately, soil functioning.
We present a NuSTAR and XMM–Newton monitoring campaign in 2014/2015 of the Compton-thick Seyfert 2 galaxy, NGC 1068. During the 2014 August observation, we detect with NuSTAR a flux excess above ...20 keV (32 ± 6 per cent) with respect to the 2012 December observation and to a later observation performed in 2015 February. We do not detect any spectral variation below 10 keV in the XMM–Newton data. The transient excess can be explained by a temporary decrease of the column density of the obscuring material along the line of sight (from N
H ≃ 1025 cm−2 to N
H = 6.7 ± 1.0 × 1024 cm−2), which allows us for the first time to unveil the direct nuclear radiation of the buried active galactic nucleus in NGC 1068 and to infer an intrinsic 2–10 keV luminosity L
$_{\rm X}=7^{+7}_{-4} \times 10^{43}$
erg s−1.
The baculovirus expression system was found to be efficient at expressing the 3D, the 3AB and the 3ABC non-structural proteins (NSP) of foot-and-mouth disease virus (FMDV) as antigens recognised by ...immune sera in ELISA. ELISA's using 3D, 3AB and 3ABC detected antibodies from day 8 and 10 after experimental infection of susceptible cattle and sheep and cattle remained seropositive for more than 395 days. The ELISA's detected antibodies against any of the seven serotypes of FMDV. The 3D ELISA was specific and precise and as sensitive as established ELISA's which measure antibody to structural proteins. The assay may be used as a resource saving alternative to established ELISA's for the detection of antibodies against any of the seven serotypes. The 3AB and the 3ABC ELISA were also specific and precise. FMDV infected cattle could be differentiated from those that had been merely vaccinated as they gave a positive result in both the 3AB and the 3ABC ELISA's. Two cattle that had been both vaccinated and infected also gave positive results in both tests, suggesting that the 3AB and 3ABC ELISA's, but not the 3D ELISA might represent a reliable means of detecting infection in a vaccinated population.
BoltzTraP2 is a software package for calculating a smoothed Fourier expression of periodic functions and the Onsager transport coefficients for extended systems using the linearized Boltzmann ...transport equation. It uses only the band and k-dependent quasi-particle energies, as well as the intra-band optical matrix elements and scattering rates, as input. The code can be used via a command-line interface and/or as a Python module. It is tested and illustrated on a simple parabolic band example as well as silicon. The positive Seebeck coefficient of lithium is reproduced in an example of going beyond the constant relaxation time approximation.
Program Title:BoltzTraP2
Program Files doi:http://dx.doi.org/10.17632/bzb9byx8g8.1
Licensing provisions: GPLv3
Programming language: Python and C++
External routines/libraries: NumPy, SciPy, Matplotlib, spglib, ase, fftw, VTK, netCDF4, Eigen
Nature of problem: Calculating the transport coefficients using the linearized Boltzmann transport equation within the relaxation time approximation.
Solution method: Smoothed Fourier interpolation
Titanium dioxide (TiO₂) has a number of uses in catalysis, photochemistry, and sensing that are linked to the reducibility of the oxide. Usually, bridging oxygen (Obr) vacancies are assumed to cause ...the Ti3d defect state in the band gap of rutile TiO₂(110). From high-resolution scanning tunneling microscopy and photoelectron spectroscopy measurements, we propose that Ti interstitials in the near-surface region may be largely responsible for the defect state in the band gap. We argue that these donor-specific sites play a key role in and may dictate the ensuing surface chemistry, such as providing the electronic charge required for O₂ adsorption and dissociation. Specifically, we identified a second O₂ dissociation channel that occurs within the Ti troughs in addition to the O₂ dissociation channel in Obr vacancies. Comprehensive density functional theory calculations support these experimental observations.
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