Thermoelectric properties of Co, Ir, and Os-Doped FeSi Alloys: Evidence for Strong Electron-Phonon Coupling

The effects of various transition metal dopants on the electrical and thermal transport properties of Fe1-xMxSi alloys (M= Co, Ir, Os) are reported. The maximum thermoelectric figure of merit ZTmax is improved from 0.007 at 60 K for pure FeSi to ZT = 0.08 at 100 K for 4% Ir doping. A comparison of the thermal conductivity data among Os, Ir and Co doped alloys indicates strong electron-phonon coupling in this compound. Because of this interaction, the common approximation of dividing the total thermal conductivity into independent electronic and lattice components ({\kappa}Total = {\kappa}electronic + {\kappa}lattice) fails for these alloys. The effects of grain size on thermoelectric properties of Fe0.96Ir0.04Si alloys are also reported. The thermal conductivity can be lowered by about 50% with little or no effect on the electrical resistivity or Seebeck coefficient. This results in ZTmax = 0.125 at 100 K, still about a factor of five too low for solid-state refrigeration applications

Partial cross sections for dissociative electron attachment to tetrahydrofuran reveal a dynamics-driven rich fragmentation pattern

We report partial absolute cross sections for dissociative electron attachment (DEA) to tetrahydrofuran C₄H₈O. The high sensitivity of the present setup, quantitative DEA spectrometer with time-of-flight analyzer, led to identification of a number of previously unreported fragments (CH₂⁻, OH⁻, CHO⁻, C₄H₅O⁻, C₃H₃⁻) thus revealing complex dissociation dynamics of the involved resonant states. The chemical composition of fragment anions was assigned by experiments with completely deuterated tetrahydrofuran. We also show that the dominant heavy anionic fragment with m/z = 41 is C₃H₅⁻ anion rather than C₂HO⁻ as reported in the previous studies, in spite of the fact that formation of the latter one is energetically more favorable. The dynamics on the resonant state is thus more decisive for the reaction outcome than the asymptotic energetics. The assignment of resonances and their dynamic pathways is discussed by using comparison with recent complementary experiments that characterize electronic states of neutral and ionic tetrahydrofuran

Effect of Corrosion on the Low-cycle Fatigue Strength of Steels used in Frequent Start-up Power Generation Steam Turbine

AbstractThe practical importance of fatigue failure in steam turbine materials has directed many experimental research towards assessing the physical reason for material sensitivity to corrosion fatigue and providing design rules for engineers. Metallic materials used in steam turbine are exposed to cyclic loading at high temperature and steam environment, during their service life. In this study, an original fatigue testing setup was developed to investigate the effect of aqueous solutions and temperature on the fatigue strength on the martensitic stainless steel X19CrMoVNbN11-1 used for rotating blades and (ii) a cast G17CrMoV5-10 steel used for casing. Fatigue tests were carried out in two environments: (i) in air at 90°C and (ii) in distilled water at 90°C (pH = 7.2 and 02 = 3 ppm) at a loading frequency of 1Hz. Internal and surface crack initiation are observed in air at 90°C, whereas in purified water at 90°C, the crack initiated in the surface at corrosion defects. The decrease observed in the corrosion fatigue strength of specimens was more important at high plastic strain level of that on similar specimens tested in air. Based on fractography analysis, fatigue crack initiation mechanisms in air and in distilled water were identified. Two different scenarios for fatigue damage depending on the microstructure are proposed and will be discussed in this paper

Phonon anharmonicity and negative thermal expansion in SnSe

The anharmonic phonon properties of SnSe in the Pnma phase were investigated with a combination of experiments and first-principles simulations. Using inelastic neutron scattering (INS) and nuclear resonant inelastic X-ray scattering (NRIXS), we have measured the phonon dispersions and density of states (DOS) and their temperature dependence, which revealed a strong, inhomogeneous shift and broadening of the spectrum on warming. First-principles simulations were performed to rationalize these measurements, and to explain the previously reported anisotropic thermal expansion, in particular the negative thermal expansion within the Sn-Se bilayers. Including the anisotropic strain dependence of the phonon free energy, in addition to the electronic ground state energy, is essential to reproduce the negative thermal expansion. From the phonon DOS obtained with INS and additional calorimetry measurements, we quantify the harmonic, dilational, and anharmonic components of the phonon entropy, heat capacity, and free energy. The origin of the anharmonic phonon thermodynamics is linked to the electronic structure.Comment: 14 pages, 12 figure

Audio-visual fine-tuning of audio-only ASR models

Audio-visual automatic speech recognition (AV-ASR) models are very effective at reducing word error rates on noisy speech, but require large amounts of transcribed AV training data. Recently, audio-visual self-supervised learning (SSL) approaches have been developed to reduce this dependence on transcribed AV data, but these methods are quite complex and computationally expensive. In this work, we propose replacing these expensive AV-SSL methods with a simple and fast \textit{audio-only} SSL method, and then performing AV supervised fine-tuning. We show that this approach is competitive with state-of-the-art (SOTA) AV-SSL methods on the LRS3-TED benchmark task (within 0.5% absolute WER), while being dramatically simpler and more efficient (12-30x faster to pre-train). Furthermore, we show we can extend this approach to convert a SOTA audio-only ASR model into an AV model. By doing so, we match SOTA AV-SSL results, even though no AV data was used during pre-training

Evaluation of a Method of Estimating Agricultural Chemical Use

This research evaluated the validity of an economic-based measure of agricultural chemical use on specific crop types. Estimated chemical use measures, reported in a budget planning document prepared collaboratively with input from farmers, vendors, researchers, and representatives from numerous agricultural agencies, were compared to chemical use measures collected through face-to-face interviews with local farmers regarding their actual chemical application practices over the past growing season. A rural agricultural-based county in Mississippi, USA, was the study area for this project. The measures of comparison were the estimated and actual ounces of individual fungicides, herbicides, and insecticides used per acre on corn, rice, soybean, wheat, and cotton fields, and the estimated and actual total chemical load, which is the sum of all fungicides, herbicides and insecticides used on the various crops. To obtain information regarding crop type and area of cultivated land, contemporary satellite images, overlaid with property maps, were plotted and provided for the farmers to identify their crop types and delineate their crop boundaries. The crop boundaries were digitized, and a GIS database was developed containing data for crop types, amounts of cultivated land, and chemical types and quantities used. Outcomes of this research could assist in studies requiring agricultural chemical data by using estimates generated by the USDA and other agricultural agencies as an alternative to primary data collection

Slipped capital femoral epiphysis management and the arthroscope

BACKGROUND: In situ pinning of slipped capital femoral epiphysis (SCFE) results in various degrees of deformity of the femoral head-neck junction. Repetitive trauma from cam-type femoroacetabular impingement (FAI) can lead to labral tears and injury to the articular cartilage causing loss of function. Arthroscopic osteoplasty is an alternative to open procedure and to Southwick/Imhäuser-type osteotomies in symptomatic selected cases. SURGICAL TECHNIQUE: The amount of bone to be resected has to be carefully planned pre-operatively. Only gentle traction is applied on a well-padded perineal support. A spherical burr is used to gradually resect the prominence. Intra-operative fluoroscopy is very useful when checking adequate reshaping of the head-neck junction is obtained. RESULTS: Arthroscopy often reveals acetabular cartilage lesions, labrum hyperhemia and fraying which rarely require repair. Arthroscopic osteoplasty provides satisfactory pain relief and, to a lesser extent, restores hip internal rotation. CONCLUSION: Arthroscopic osteoplasty is more technically and time-demanding in post SCFE than idiopathic FAI. It requires strong arthroscopic skills and experience in hip arthroscopy. It stands as a reasonable alternative to open procedure or flexion osteotomies in symptomatic FAI post mild to moderate SCFE. It provides pain relief and to a lesser extent restores internal rotation of the hip

Nanocapillary sampling coupled to liquid chromatography mass spectrometry delivers single cell drug measurement and lipid fingerprints

This work describes the development of a new approach to measure drug levels and lipid fingerprints in single living mammalian cells. Nanocapillary sampling is an approach that enables the selection and isolation of single living cells under microscope observation. Here, live single cell nanocapillary sampling is coupled to liquid chromatography for the first time. This allows molecular species to be separated prior to ionisation and improves measurement precision of drug analytes. The efficiency of transferring analytes from the sampling capillary into a vial was optimised in this work. The analysis was carried out using standard flow liquid chromatography coupled to widely available mass spectrometry instrumentation, highlighting opportunities for widespread adoption. The method was applied to 30 living cells, revealing cell-to-cell heterogeneity in the uptake of different antibiotics. Using this system, we detected 14-158 lipid features per single cell, revealing the association between bedaquiline uptake and lipid fingerprints