Development of Phonon Dynamics Measurement System by MIR- FEL and Pico-second Laser

FEL2015, Daejeon, Republic of KoreaCoherent control of a lattice vibration in bulk solid (mode-selective phonon excitation: MSPE) is one of the attractive methods in the solid state physics because it becomes a powerful tool for the study of ultrafast lattice dynamics (e.g. electron-phonon interaction and phonon-phonon interaction). Not only for that, MSPE can control electronic, magnetic, and structural phases of materials. In 2013, we have directly demonstrated MSPE of a bulk material with MIR-FEL (KU-FEL) by anti-Stokes Raman scattering spectroscopy. For the next step, we are starting a phonon dynamics measurement to investigate the difference of physical property between thermally excited phonon (phonon of equilibrium state) and optically excited phonon (phonon of non-equilibrium state) by time-resolved method in combination with a pico-second VIS laser. By using pico-second laser, we also expect to perform the anti-Stokes hyper-Raman scattering spectroscopy to extend MSPE method to the phonon mode which has Raman inactive . As the first step, we have commissioned the time-resolved phonon measurement system and started measurement on 6H-SiC. In this conference, we will present the outline of measurement system, and experimental results

1-Year Results of the ZEPHYR Registry (Zilver PTX for the Femoral Artery and Proximal Popliteal Artery) Predictors of Restenosis

AbstractObjectivesThis study sought to assess the rate and predictors of 1-year restenosis after drug-eluting stent implantation for femoropopliteal (FP) lesions in patients with peripheral arterial disease.BackgroundZilver PTX, a paclitaxel-eluting stent for FP lesions, provides superior outcomes to angioplasty and bare-metal stents in clinical trials. However, its real-world outcomes and the associated features remain unclear.MethodsThis was a prospective multicenter study enrolling 831 FP lesions (797 limbs, 690 patients) treated by Zilver PTX implantation. The primary endpoint was 1-year restenosis. Secondary endpoints included major adverse limb event and stent thrombosis.ResultsMean lesion length was 17 ± 10 cm. One-year restenosis, major adverse limb event, and stent thrombosis rates were 37%, 22%, and 2%, respectively. The generalized linear mixed model showed that lesion length ≥16 cm assessed by angiography and distal external elastic membrane area ≤27 mm2 and minimum stent area ≤12 mm2 assessed by intravascular ultrasound were independent risk factors for restenosis. One-year restenosis rates were 15% in cases with none of these risk factors and 50% in those with ≥2 risk factors.ConclusionsThe current study demonstrated 1-year real-world outcomes after drug-eluting stent treatment for FP lesions, including challenging ones in clinical practice. Lesion length, external elastic membrane area, and minimum stent area were independent predictors for restenosis. (Zilver PTX for the Femoral Artery and Proximal Popliteal Artery—Prospective Multicenter Registry [ZEPHYR]; UMIN000008433

Electroanalytical overview: The electroanalytical detection of theophylline

In this overview, we explore the electroanalytical determination of theophylline. Theophylline finds use as a bronchodilator for treating diseases such as asthma and chronic obstructive pulmonary disease (COPD). There is a need to measure the concentration of theophylline in pharmaceuticals for QA/QC purposes as well as in plasma samples to ensure the doses of theophylline are at the correct therapeutic levels. If the concentration levels of theophylline deviate from the therapeutic levels (10–20 µg/mL for asthma), then patients can experience adverse effects. As such, there is a desire to progress from traditional laboratory based techniques to portable rapid testing. In this overview, we review the endeavours directed to the development of theophylline electroanalytical sensors, noting current and future trends

“Pseudo aortoiliac bifurcation” leading to significant plaque shifting in the endovascular treatment of an aortoiliac bifurcation lesion: a case report

Abstract Background Plaque shifting is a serious complication of endovascular treatment (EVT) for aortoiliac bifurcation lesions. It is challenging to predict the occurrence of unfavorable plaque shifting correctly. Case presentation We report the case of an 88-year-old Japanese woman who experienced constant pain at rest in her left leg. The ankle-brachial pressure index of her left leg was 0.57. Computed tomography (CT) angiography revealed severe stenosis of the left common iliac artery (CIA) and total occlusion of the left external iliac artery (EIA). We diagnosed the patient with acute exacerbation of a chronic limb ischemia and administered endovascular treatment (EVT) to treat the left CIA and EIA. The results of initial angiography agreed with those of CT angiography. After placing a self-expandable stent for the left CIA lesion, significant unfavorable plaque shifting occurred. From a comparison between pre- and post-stenting angiography, we realized that the plaque protrusion into the terminal aorta had formed a “pseudo aortoiliac bifurcation” that was situated more proximally compared to the true bifurcation. We had incorrectly assessed the height of the aortoiliac bifurcation and exact plaque position and had underestimated the risk of plaque shifting because of this misunderstanding. The patient ultimately developed fatal cholesterol embolization after EVT. Conclusions Plaque protrusion into the terminal aorta can form a “pseudo aortoiliac bifurcation”, causing the wrong estimation of the height of the aortoiliac bifurcation; “angiographically”, the highest point is not always the true bifurcation. Careful assessment of initial angiography to detect the true aortoiliac bifurcation and exact plaque position is essential to avoid unfavorable plaque shifting

Mode-selective phonon excitation in gallium nitride using mid-infrared free-electron laser

The single-phonon mode was selectively excited in a solid-state sample. A mid-infrared free-electron laser, which was tuned to the target phonon mode, was irradiated onto a crystal cooled to a cryogenic temperature, where modes other than the intended excitation were suppressed. An A 1(LO) vibrational mode excitation on GaN(0001) face was demonstrated. Anti-Stokes Raman scattering was used to observe the excited vibrational mode, and the appearance and disappearance of the scattering band at the target wavenumber were confirmed to correspond to on and off switching of the pump free-electron laser and were fixed to the sample vibrational mode. The sum-frequency generation signals of the pump and probe lasers overlapped the Raman signals and followed the wavenumber shift of the pump laser

Two-photon selective excitation of phonon-mode in diamond using mid-infrared free-electron laser

Two-photon selective excitation of an infrared (IR)-inactive phonon mode by a mid-infrared tunable free-electron laser (FEL) was accomplished. The mode-selective phonon excitation of IR-active mode by one-photon excitation using FEL (Yoshida et al. (2013) [20]) was extended to the IR-inactive mode excitation. The T2g optical phonon mode in single-crystal diamond at 1, 332cm−1 was selected, and the FEL photon energy corresponding to the oscillation wavelength was tuned to the half of the target phonon energy. The successful mode excitation was confirmed by anti-Stokes Raman scattering signal of T2g for the sample at cryogenic temperature, where all other modes were suppressed. The signal was observed at T2g phonon energy with red-shift of the peak to 1, 306cm−1, which was accompanied by surface damage induced by intense laser irradiations

Experimental demonstration of mode-selective phonon excitation of 6H-SiC by a mid-infrared laser with anti-Stokes Raman scattering spectroscopy

中赤外レーザーを用いた格子振動の選択励起を世界で初めて直接観測 -原子の振動を光で自在に操作-. 京都大学プレスリリース. 2013-11-29.Mode-selective phonon excitation by a mid-infrared laser (MIR-FEL) is demonstrated via anti-Stokes Raman scattering measurements of 6H-silicon carbide (SiC). Irradiation of SiC with MIR-FEL and a Nd-YAG laser at 14 K produced a peak where the Raman shift corresponds to a photon energy of 119 meV (10.4 μm). This phenomenon is induced by mode-selective phonon excitation through the irradiation of MIR-FEL, whose photon energy corresponds to the photon-absorption of a particular phonon mode