A two-temperature (2-T) model for tungsten inert gas (TIG) welding process is developed to investigate the arc phenomena of the pure argon and helium plasmas. The model considers the energy ...conservations of the heavy particles and the electrons separately. Compared with the 1-T model, the 2-T model obtains the plasma shapes more similar to the arc appearances. Furthermore, the heavy particle temperature of the 2-T model shows good agreement with the experimental results. For a pure helium arc, the electron temperature is much higher than the heavy particle temperature, whereas both temperatures are almost identical for a pure argon arc. Thermal non-equilibrium of a pure helium arc is discussed in terms of the energy exchange between heavy particles and electrons. It is found that ions and atoms of a pure helium arc cannot exchange their energy sufficiently with electrons because the plasma has a small number of electrons and consequently the collision rate between plasma species is relatively low. The simulation results show that when a welding current is lower, thermal non-equilibrium of an arc plasma is stronger. In a low welding current condition, not only the pure helium arc but also the pure argon arc shows thermal non-equilibrium.
Extending the limit of charge-carrier mobility in semiconductors has been a long-standing pursuit in material science and its applications. Herein, we investigate the electron mobility via cyclotron ...resonance in undoped diamond under continuous-wave photoexcitation, whereby the density of charge carriers can be reduced to 10 8 cm −3 or 1/10 of the previous detection limit K. Konishi et al., Appl. Phys. Lett. 117, 212102 (2020) . For low-density electrons, which obviate the effects of carrier-carrier scattering as a broadening mechanism, we observe an extraordinarily narrow cyclotron resonance spectrum. After correcting for the microwave power broadening, the highest intrinsic mobility value of 100×10 6 cm 2 V −1 s −1 is obtained at 3 K, which is a 16-fold increase of the mobility compared with the previous record in diamond. Our result is beneficial for the design and application of diamond radiation detectors implemented for their practical use at cryogenic temperatures.
We examine the mechanism responsible for the optical activity of a two-dimensional array of gold nanostructures with no mirror symmetry on a dielectric substrate. Measurements with different incident ...angles, polarizations and sample orientations allow us to reveal that observed polarization effect is enhanced by surface plasmon resonance. By performing numerical simulation with rigorous diffraction theory we also show that the grating chirality can be described in terms of the non-coplanarity of the electric field vectors at the front (air-metal) and back (substrate-metal) sides of the grating layer.
We present observations of SCP 06F6, an unusual optical transient discovered during the Hubble Space Telescope Cluster Supernova Survey. The transient brightened over a period of ~100 days, reached a ...peak magnitude of ~ 21.0 in both i 775 and z 850, and then declined over a similar timescale. There is no host galaxy or progenitor star detected at the location of the transient to a 3 sigma upper limit of i 775 >= 26.4 and z 850 >= 26.1, giving a corresponding lower limit on the flux increase of a factor of ~ 120. Multiple spectra show five broad absorption bands between 4100 A and 6500 A, and a mostly featureless continuum longward of 6500 A. The shape of the light curve is inconsistent with microlensing. The transient's spectrum, in addition to being inconsistent with all known supernova types, does not match any spectrum in the Sloan Digital Sky Survey database. We suggest that the transient may be one of a new class.
The ferromagnetic state of the spin-polarized ferromagnet La1−xSrxMnO3 is stabilized in the metallic region by strong coupling between localized spins in the t2g orbital and conduction electrons in ...the eg orbital. We prepared polycrystalline La1−xSrxMnO3 films (x = 0.15, 0.25, or 0.30) by deposition on an oxidized Si substrate. The three types of La1−xSrxMnO3 films were in the ferromagnetic rhombohedral phase, and their Curie temperatures, TC, evaluated from the midpoint of ac magnetization, were 305 K, 335 K, and 338 K, respectively. By applying expansion-mode acoustic vibration to the crystal structure of La1−xSrxMnO3, we observed a remarkable decrease (as large as 70 K) in TC. The applied structural perturbation causes a decrease in the possibility of conduction electron hopping and an increase in the Jahn–Teller distortion. The former is more effective for decreasing TC than the latter.
Since the best chemotherapy regimen for each patient with advanced gastric cancer is uncertain, we aimed to identify molecular prognostic or predictive biomarkers from biopsy specimens in JCOG9912, a ...randomized phase III trial for advanced gastric cancer.
Endoscopic biopsy specimens from primary lesions were collected in 445 of 704 randomized patients in JCOG9912. We measured the mRNA expression of excision repair cross-complementing group 1 (ERCC1), thymidylate synthase, dihydropyrimidine dehydrogenase, and five other genes, then, categorized them into low and high groups relative to the median, and examined whether gene expression was associated with efficacy end point.
Multivariate analyses showed that high ERCC1 expression HR 1.37; 95% confidence interval (CI) 1.08–1.75; P = 0.010, performance status ≥1 (HR 1.45; 95% CI 1.13–1.86; P = 0.004), and number of metastatic sites ≥2 (HR 1.66; 95% CI 1.28–1.86; P < 0.001) were associated with a poor prognosis, and recurrent disease (versus unresectable; HR 0.75; 95% CI 0.56–1.00; P = 0.049) was associated with a favorable prognosis. None of these molecular factors were a predictive marker for choosing irinotecan plus cisplatin or 5-fluorouracil rather than S-1.
These correlative analyses suggest that ERCC1 is an independent prognostic factor for overall survival in the first-line treatment of gastric cancer.
C000000062, www.umin.ac.jp.
In this study, a bacteria detection apparatus based on dielectrophoretic impedance measurement (DEPIM) method was demonstrated for rapid evaluation of oral hygiene. The authors integrated a micro ...electrode chip on which bacteria were captured by dielectrophoresis (DEP), an AC voltage source to induce DEP force, and an impedance measurement circuit to a portable instrument that enables rapid and automated oral bacterial inspection in hospitals and clinics. Special considerations have been made on effects of high electrical conductivity of oral samples on DEP force and DEPIM results. It was shown experimentally and theoretically that using a higher electric field frequency for the DEP bacteria trap and the impedance measurement could realise DEPIM application to bacteria inspection from oral samples with higher conductivity. Based on these investigations, the authors optimised the frequency condition of the DEPIM suitable for inspecting an oral sample along with the design and development of a portable DEPIM apparatus for on-site inspection of oral bacteria. Under the optimised frequency condition, DEPIM results were in good agreement with the conventional culture method showing significant applicability of the DEPIM apparatus for practical rapid oral bacteria inspection.
We report the results of an experimental study on the focusing of broadband terahertz (THz) radiation using lenses and Fresnel zone plates. The obtained data are compared with the results of ...numerical simulations. It is shown that the use of lenses for focusing THz radiation can lead to the appearance of a ring structure in the spatial distributions of its intensity. The use of Fresnel zone plates allows the spatial distribution of the THz radiation intensity to be varied at selected frequencies of the spectrum.
We have analysed multiband light curves of 328 intermediate-redshift (0.05 less than or equal to z < 0.24) Type Ia supernovae (SNe Ia) observed by the Sloan Digital Sky Survey-II Supernova Survey. ...The multiband light curves were parametrized by using the multiband stretch method, which can simply parametrize light-curve shapes and peak brightness without dust extinction models. We found that most of the SNe Ia that appeared in red host galaxies (u - r > 2.5) do not have a broad light-curve width and the SNe Ia that appeared in blue host galaxies (u - r < 2.0) have a variety of light-curve widths. The Kolmogorov-Smirnov test shows that the colour distribution of SNe Ia appearing in red/blue host galaxies is different (a significance level of 99.9 per cent). We also investigate the extinction law of host galaxy dust. As a result, we find that the value of R sub( v) derived from SNe Ia with medium light-curve widths is consistent with the standard Galactic value, whereas the value of R sub( v) derived from SNe Ia that appear in red host galaxies becomes significantly smaller. These results indicate that there may be two types of SNe Ia with different intrinsic colours, and that they are obscured by host galaxy dust with two different properties.
PDF
