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Interaction between forced and chatter vibrations through flank-workpiece interference
No full textIn this paper, the interaction between forced and chatter vibrations through flank-workpiece interference is studied. The effect of the well-known process damping, which occurs due to the contact between the flank face and the workpiece, on the chatter stability has been studied broadly. However, this contact should occur by forced vibration also, which has not been studied much in the literature. Due to this contact, forced vibration should suppress chatter, and vice versa; interaction should occur. A model is constructed to evaluate this interaction, and the interactive effects are clarified through simulations and experiments.journal articl
Semiconductor-Type Gas Sensors Based on Surface-Modified Iron Oxide Nanoparticles for ppb-Level Detection of Acetone
No full textVolatile organic compounds (VOCs) at parts-per-billion (ppb) concentrations in biological gases, such as human breath and skin emissions, are recognized as potential disease biomarkers. As a result, biological gas analysis has attracted considerable attention as a noninvasive approach for disease screening. The purpose of this study was to propose a method to prepare a gas sensor that is capable of detecting VOCs at ppb levels by realizing the high specific surface area of a gas-sensitive layer. Iron oxide nanoparticles modified with 3,4-dihydroxyphenylacetic acid were drop-cast onto an alumina substrate with platinum electrodes to prepare the gas-sensitive layer of the gas sensor. The resistivity of the gas-sensitive layer was measured at 230 °C under dry air with and without VOC gases. The response value was calculated as Ra/Rg, where Ra is the resistance in dry air and Rg is the resistance with VOC gases. The modified nanoparticles exhibited response values of 7.8 and 9.0 for 100 ppb of acetone and acetaldehyde, respectively, substantially higher than those of unmodified iron oxide nanoparticles, which showed responses of 3.0 and 3.1. Scanning electron microscopy and nitrogen adsorption–desorption isotherm analyses revealed that the surface-modified nanoparticles possessed a high specific surface area with numerous pores possibly because the increased interparticle affinity between iron oxide nanoparticles was modified with bifunctional organic molecules. These structural features likely enhanced gas interaction, contributing to the improved sensor response compared to the unmodified counterparts. This study would contribute to screening for diseases such as diabetes with the same ease as breath alcohol testing.journal articl
Attenuation of Weak Spherical Shock Waves in an Accelerating Flow
Get PDFThis study reports experimental investigations of a weak spherical shock wave propagating into an accelerating flow induced by a fan. Pressure measurements are conducted for shock waves propagating in both a static fluid and an accelerating flow, and comparisons reveal the influence of the accelerating flow on shock wave properties. The pressure jump of the shock wave is reduced after propagation in the accelerating flow, indicating attenuation of the shock wave. Greater attenuation is observed with increasing longitudinal velocity gradient in the shock propagation direction, corresponding to higher acceleration. When the velocity gradient becomes sufficiently large, the pressure jump is no longer identifiable, implying the disappearance of the shock wave. This attenuation is consistent with the one-dimensional model of a shock wave crossing a surface with an infinitely large velocity gradient, as the experimental conditions approach those of the model with increasing gradient. The attenuation does not affect the fluctuating behavior of the pressure jump. Additionally, the histogram of pressure jumps suggests that attenuation occurs for all shock waves propagating in the accelerating flow. The present experimental results support the shock wave attenuation predicted by the one-dimensional model, offering new insights into shock wave propagation in non-uniform flows.journal articl
Broken time-reversal symmetry detected by point-contact spectroscopy of superconducting Pd-doped CaAgP
Get PDFThe appearance of broken time-reversal symmetry (TRS) in superconducting states is an intriguing issue in solid-state physics because of the incompatibility of the spontaneous magnetic field and the Meissner effect. We identify broken TRS in Pd-doped CaAgP (CaAg0.9Pd0.1P ) by point-contact spectroscpy through the magnetic-field response of conductance spectra. CaAg0.9Pd0.1P is a nodal-line semi-metal with exotic electronic states such as drumhead surface states and surface superconductivity. Tunneling conductance spectra acquired at the side surfaces of CaAg0.9Pd0.1P under an applied magnetic field exhibit broad zero-bias peaks with small asymmetric structures. Surprisingly, the asymmetric structures are reversed exactly by flipping the field direction. On the basis of an analysis which stands on the formula of tunneling junctions for unconventional superconductors, these results are consistent with the pair potential of the superconductivity breaks with the TRS and is strongly coupled to an external magnetic field. We reveal the novel character of superconducting nodal-line semi-metals by developing the TRS sensitivity of point-contact spectroscopy. Our results serve as an exploration of broken TRS in superconducting states realized in topological materials.journal articl
Multicenter randomized phase III study of high-dose therapy with autologous stem cell transplantation versus observation for patients with newly diagnosed peripheral T-cell lymphoma who achieved complete metabolic response after induction therapy (JCOG2210, TRANSFER study)
Get PDFPatients with peripheral T-cell lymphoma demonstrated a poor prognosis after obtaining a complete response with induction treatment compared to those with B-cell lymphoma. Once it relapsed, curative treatment is frequently limited to invasive treatments with significant treatment-related mortality, including allogeneic stem cell transplantation. The limitations of these treatment choices indicate the necessity for developing optimal consolidation therapies to prevent relapse. This multicenter randomized phase III trial aims to confirm the superiority of the high-dose therapy with autologous stem cell transplantation over observation alone in terms of progression-free survival for patients with newly diagnosed peripheral T-cell lymphoma who achieved complete metabolic response after induction therapy. A total of 140 patients from 52 hospitals will be enrolled in Japan over 5.5 years. This trial is registered in the Japan Registry of Clinical Trials as jRCTs031240169 (https://jrct.niph.go.jp/latest-detail/jRCTs031240169).Online Published: 19 October 2024journal articl
