Y. Suzuki

National Institute of Public Health, Saitama, Saitama, Japan

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Publications (68)39.65 Total impact


  • No preview · Article · Oct 2015 · ECS Transactions
  • T. Ito · Y. Suzuki · A. Koike · Y. Neo · H. Mimura · T. Aoki
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    ABSTRACT: To investigate mechanisms of the polarization phenomena in the CdTe radiation detectors, we used optical laser pulses for carrier generation and detected the electrical response from the CdTe detectors as a function of carrier-generation position in the detector. Temporal change of the internal electric field at defined position in the CdTe detector can be directly observed by the laser pulse measurements. Detectors measured in this study were Schottky-type CdTe detectors with a thickness of 0.5 mm and a size of 2 × 1 mm2. Laser light from laser diode with a wavelength of 850 nm were modulated to pulses by using pulse generator and were irradiated to the cleaved side surface of the CdTe detectors. The incident pulse power was 10 nW, which correspond to one photon energy of γ-lay with a energy of several tens of keV. Time traces of output voltage amplified by preamplifier were measured by oscilloscope as a function of time after applying bias voltage. Pulse height and rise-up time was obtained from the time trace of the output voltage. The pulse height was decreased and the rise-up time was increased as a function of the time. Rate of these changes are larger at cathode side than anode side. Depletion layer in the detector is assumed to be shrunk and internal electric field in cathode side is decreased with time. The change of internal electric field is considered to be caused by carrier accumulation to deep acceptor level.
    No preview · Article · Jan 2013
  • T. Ito · Y. Suzuki · A. Koike · H. Mori · Y. Neo · H. Mimura · T. Aoki
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    ABSTRACT: To investigate temporal change of the output signal from the CdTe detectors, optical laser pulses was used for carrier generation. Electrical responses from the CdTe detectors were detected as a function of generated carrier density and applied bias voltage. Temporal change of the internal electric field at defined position in the CdTe detector can be directly observed by the laser pulse measurements. Laser pulses were irradiated to the center of the cleaved side surface of the CdTe detectors. Time traces of output voltage amplified by charge-sensitive preamplifier were measured by oscilloscope as a function of time after applying bias voltage. The pulse height was decreased and the rise-up time was increased as a function of the time. Rate of these changes were increase with decreasing the applied bias voltage and with increasing incident laser power, which corresponds to carrier density generated in the detector. It is concerned that the distribution of the depletion layer are modified and the electric field at the center of the detector are decreased with the time under bias voltage by the polarization phenomena.
    No preview · Conference Paper · Jan 2012
  • Y Suzuki · M Katoh · J Sato · M Morokuma · M A Hosoi · C Ohkubo
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    ABSTRACT: This study explored the pressure pain threshold (PPT) of the mucosa after tooth extraction. The PPTs of the wounded mucosa of eight volunteer subjects were observed at 7, 30, and 90 days after tooth extraction. The PPTs at 30 days and 90 days were approximately two and three times higher respectively, than those at 7 days. As time passed, the values for the PPTs after tooth extraction increased in all regions. At 90 days after tooth extraction, the PPTs are about 97% recovered compared to the PPTs of the contralateral points.
    No preview · Article · Dec 2011 · The European journal of prosthodontics and restorative dentistry
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    ABSTRACT: The experiment exposing the millimeter-wave (MMWs) is performed to investigate the relation between the temperature elevation at the ocular tissue and MMW exposure. The temperature and velocity distributions in front part of the eye are simultaneously measured by using Micro-Encapsulated Thermo-chromic Liquid Crystal and Fluoroptic Thermometer. It is found that the flowing patterns of aqueous humor depend on the incident power density, and these patterns affect the heat transport mechanism.
    Full-text · Conference Paper · Sep 2011
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    ABSTRACT: To evaluate biological effects of intermediate frequency magnetic fields (IF-MFs), we developed an exposure system for in vitro study. This system is able to generate up to 3.9mT, 21kHz IF-MF under controlled culture condition. Toxicity and effect on frequency of micronucleus in CHL/IU cells by exposure to IF-MFs were investigated. As the results, we have not observed any significant effects by exposure to 21 kHz, up to 3.9 mT IF-MF in both experiment. This suggests that IF-MF is unlikely to cause adverse biological effects.
    Full-text · Conference Paper · Sep 2011
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    ABSTRACT: Since the opportunities that people are exposed to intermediate frequency (IF) magnetic fields (MF) are increasing, the health risk assessment of IF-MF has now become important. Because there have been few studies about long-term exposure to IF-MF with high magnetic flux density, we have developed a new apparatus capable of IF-MF exposure up to 3.9 mT for in vitro study. In this study, we found out that IF-MF did not affect both cell growth and mutagenicity using the mammalian cell line CHO-K1 and its DNA repair deficient derivatives.
    Full-text · Conference Paper · Sep 2011
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    ABSTRACT: The acute ocular injury threshold of 76 GHz band millimeter wave (MMW) exposure was investigated using an in vivo rabbit model. Pigmented rabbits were exposed unilaterally to 200, 100, 75, 50, 10 mW/cm<sup>2</sup> 76 GHz band MMW for 6 min with a lens antenna. Corneal opacity, epithelial injury, miosis, and ocular inflammation were present up to 2-3 days after exposure at a dose of 200 mW/cm<sup>2</sup>. No ocular changes other than reversible corneal epithelial injury were seen following exposure at 100 and 75 mW/cm<sup>2</sup>. There were no ocular changes after exposure at doses of 50 or 10 mW/cm<sup>2</sup>. Six-minute exposure to 76 GHz 10 mW/cm<sup>2</sup> did not induce any detectable ocular tissue damage.
    Full-text · Conference Paper · Sep 2011
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    ABSTRACT: 2and 64×48 μm 2 , respectively, and the estimated roughness values were 0.51 and 0.29 nm (rms) for the AFM and interferometer observations, respectively. We did not observe any crosshatch pattern, as seen in previous work using the Ge condensation method. The degradation of surface roughness during RTA was very small, indicating the suppression of surface roughening by the capping SiO2 layer during RTA. Figure 2 shows the x-ray reciprocal space maps (XRSMs) around the 224 Bragg reflection of the SOI layers for the samples with Ge/SOI layers with thicknesses of 35/57 and 35/22 nm. The SOI structure of the starting material was formed by a layer transfer technique, and a slight unintentional misorientation was present between the SOI layer and Si substrate, so that the reflection of the substrate was shifted from that of the SOI layer as shown in Fig. 2(a). The reflection of the SiGe layer was observed on the dashed line denoted as 'relaxed' in the figure and is located near the midpoint between the SOI reflection and that calculated for the fully relaxed Ge crystal. These results indicate the epitaxial growth of a single-crystalline fully relaxed SiGe layer on the SOI substrate. The Ge concentration is estimated to be 54% from the center
    No preview · Article · Jan 2011
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    ABSTRACT: Due to the lack of the science based evidences, we explored short term exposure effects of intermediate frequency of magnetic fields (IF-MF) to the experimental animals. Male Sprague-Dawley rats (6-7 week old) were divided into 4 groups; cage-control, sham, 2 mT and 3.8 mT exposure group, respectively. IF-MF at 21 kHz was exposed to the animals under fixed conditions in an acrylic holder. Exposure was done at 1hour/day for 3 consecutive days. On the 4th day following the exposure, biochemical and hematological parameters in the blood were analyzed. We also examined the effects to the immunological functions such as cytotoxic activity and phagocytotic activity. Results indicate that there is no effects to these parameters, even high magnetic flux density (3.8 mT; 141 times higher than the reference level to general public of ICNIRP guideline 2010) was exposed to the animals.
    No preview · Conference Paper · Jan 2011
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    ABSTRACT: This study prospectively evaluated the clinical performance of computer-assisted design and computer-assisted manufacturing (CAD/CAM)-generated In-Ceram Alumina core crowns in Japanese patients for up to 5 years. A total of 101 In-Ceram crowns with aluminium copings fabricated using the GN-I system were placed in Japanese patients. The crowns were evaluated using a California Dental Association (CDA) quality assessment system at baseline and at all follow-up examinations. Gingival condition was assessed using plaque and bleeding scores. The survival of anterior and posterior crowns was analysed according to the Kaplan-Meier method. The scores of gingival condition were compared between restored crowns and contralateral teeth using a t-test. During the observation period, six crowns were lost to follow-up. Five crowns were fractured from the copings and removed, and four crowns were removed for other reasons. Chipping within the porcelain was detected in three crowns, which were then polished. The cumulative survival rates after 60 months were 96·9% for anterior crowns and 87·7% for posterior ones, and there were no significant differences between anterior and posterior crowns. According to the CDA criteria, most of the crowns were rated as satisfactory during the observation period. There were significant differences in soft tissue conditions between In-Ceram crowns and control teeth at 2- and 5-year examinations. Despite the five fractures from copings, In-Ceram Alumina crowns with copings fabricated using the CAD/CAM (GN-I system) for replacing both anterior and posterior teeth showed predictable results during a 5-year observation period.
    No preview · Article · Dec 2010 · Journal of Oral Rehabilitation
  • S. Kogure · K. Wada · Y. Suzuki
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    ABSTRACT: This paper presents an alternating magnetic-field generator at 20 kHz for biological research using a single phase inverter and a series LC resonant circuit. Both single coil and multiple coil magnetic-field generators are designed and their effectiveness is confirmed by analytical and experimental results. These results demonstrate that the magnetic-field generator can produce 8 mT at a frequency of 20 kHz at the midpoint of the single-coil with low distortion of magnetic flux waveform. Additionally, the multiple-coil magnetic-field generator produces the distribution of uniform magnetic flux over a larger volume than the single-coil magnetic-field generator.
    No preview · Conference Paper · Oct 2009
  • H. SHIMPO · T. OSADA · N. KAMADA · Y. SUZUKI · C. OHKUBO · T. HOSOI
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    ABSTRACT: Objectives: Currently, stainless steel is being used to manufacture several types of dental reinforcing wires. The effectiveness of these materials depends on the bond strength between the denture acrylic resin and the wire. In this study, the shear bond strengths of denture acrylic resin and stainless steel were evaluated using four metal primers. Methods: The surface of commercially stainless steel plates (10 mm in diam. and 2.5 mm in thickness) were blasted with 50 mm alumina particles (0.48 MPa). Four adhesive primers [Alloy primer (Kurare, Japan), Metal primer II (GC, Japan), Metafast (San medical Japan), and Metal link (Shofu, Japan)] were applied to the blasted surface using a brush-on technique. An auto-polymerized polymethyl methacrylate denture base resin (ParaXpress, Heraeus Kulzer) was poured into a Teflon ring (a 3.0 mm circular hole) on the primed surface and polymerized according to the manufacturer's instructions. As a control, bonding specimens without priming were also prepared. After storing in distilled water for 48 hours, the shear bond strengths were measured on an autography (Instron 5565) at a crosshead speed of 0.5 mm/min. Obtained data (n=5) were analyzed using a one-way ANOVA and Tukey's Multiple Comparison Test (a=0.05). Result: The highest bond strengths were obtained with the Alloy primer (23.8 MPa) followed by Metal link (20.0 MPa), Metafast (17.3 MPa), Metal primer II (12.2 MPa), and the control (5.3 MPa). The Alloy primer exhibited significantly higher strengths than Metafast, Metal primer II, and the control (p> 0.05). Conclusion: The primed specimens significantly improved the bond strengths of denture acrylic resin to stainless steel. When stainless steel reinforcement wires are used for acrylic dentures, an Alloy primer should be applied. This research was partially supported by a research grant from the Japan Dental Association.
    No preview · Conference Paper · Apr 2009
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    ABSTRACT: Objectives: When damaged dentures are repaired, a reinforcing wire is frequently embedded in and around the broken parts to prevent further damage. Reinforcing stainless steel wires have recently become commercially available and they are used instead of cobalt-chromium alloy ones. This study assessed the bending strengths of a repaired denture base with stainless steel wires. Methods: Acrylic resin plates (2.5 x 10.0 x 65.0 mm, ParaXpress, Heraeus Kulzer) were fabricated and cut for making half-sized plates (2.5 x 10.0 x 31.5 mm). Paired cut plates were assembled while keeping a repair space of 2.0 mm in a jig; the plates were attached with three auto-polymerized resins [Unifast III (GC, Japan), Unifast Trad (GC), and Provinice (Shofu, Japan)] using a brush-on technique. The reinforcing stainless steel wires (semicircle of 2.0 mm in diameter, Yamahachi, Japan) were embedded so that they were vertically positioned to the joining surface. Before embedding, the wires were sandblasted with 50 mm alumina particles, and an Alloy Primer (Kurare, Japan) was applied on them. As controls, specimens were prepared without the wire and original resin plates. After the specimens had been stored in distilled water for 48 hours, the bending strengths were measured using the tree-point bending test (supporting lengths 30.0 mm) using autography (Instron 5565). The data were analyzed using a one-way ANOVA/ Tukey's Multiple Comparison Test (a=0.05). Result: There were no significant differences in the repaired resins (p> 0.05). Specimens with reinforcing wires showed a significantly greater bending strength than those without them (p< 0.05). Conclusion: The bending strengths of the repaired denture base with reinforcing wires using Unifast Trad were comparable to those of an undamaged denture base. Reinforcing wires should be embedded to prevent a repaired denture from becoming damaged again. Partially supported by a research grant from the Japan Dental Association.
    No preview · Conference Paper · Apr 2009
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    ABSTRACT: Objectives: To prevent breakage in acrylic dentures, reinforcing wires are frequently embedded in the denture base, particularly, in parts that are mechanically weak. Currently, several types of stainless steel wire have become commercially available and are being used to replace those made of Cobalt-chromium alloy. In this study, the effectiveness of using stainless steel reinforcing wires with acrylic resins in denture bases was evaluated. Methods: Three 18-8 stainless steel wires [a semicircle of 1.4 mm, 1.6 mm, or 2.0 mm diam. (Yamahachi, Japan)], twisted wires [2.0 mm (Dentsply Sankin, Japan)], two 18-8 stainless steel bending bars [Lingual bar and Palatal bar (Dentsply Sankin)], and a Co-Cr clasp wire [1.2 mm diam. (Dentsply Sankin)] were used as reinforcing wires. All wires were sandblasted with 50m m Al2O3 particles, and the Alloy Primer (Kuraray, Japan) was applied on their surfaces. Acrylic resin plates [2.5 x 10.0 x 65.0 mm, ParaXpress (Heraeus Kulzer, Germany)] were fabricated by embedding the wires. As a control, resin plates were prepared without the wire. After the specimens were stored in distilled water for 48 hours, the bending strengths were measured by a simple bending test using autography (Instron 5565). The data (n=5) were analyzed using a one-way ANOVA/ Tukey's Multiple Comparison Test (a=0.05). Result: The bending strengths of the Palatal bar and Lingual bar were the highest among those of all specimens tested (p<0.05). Reinforcing wires, including twisted wire, showed significantly higher strengths than the control (p< 0.05). Of the semicircle wires, the 2.0 mm wire exhibited the greatest strengths (p< 0.05). Conclusion: Excluding two bars, the 2.0 mm semicircle of stainless steel wire exhibited the highest strength. In view of both ease of handling and reinforcing effectiveness, the 2.0 mm semicircle of stainless steel wire might be recommended for fabricating the unbreakable acrylic denture.
    No preview · Conference Paper · Apr 2009
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    ABSTRACT: Objectives: Denture bases without a framework have less bending strength than those with framework; as a result, acrylic dentures frequently fail. The use of stainless steel reinforcing wire is an effective means of increasing the bending strength of dentures. This study evaluated the bending strengths of acrylic resins used in denture bases with stainless steel wires. Method: Three denture base resins using different polymerization methods [a pour-type resin, Palapress vario #1 PINK (Heraeus, Germany); a heat polymerization resin, Acron #3 PINK (GC, Japan); a microwave-curing-type resin, Acron MC #3 PINK (GC)] were used in this study. After the stainless steel wires [semicircle of 2.0 mm in diameter, (Yamahachi, Japan)] were sandblasted with 50 mm Al2O3 powder, the Alloy Primer (Kuraray Medical, Japan) was applied on their surfaces. Resin plates (2.5 x 10.0 x 65.0 mm) with and without embedded wires were fabricated with three resins using a stainless steel jig according to the manufacturer's instructions. After the specimens were stored in distilled water for 48 hours, the bending strengths (crosshead speed: 2 mm/min) were measured with a three-point bending test using autography (Instron 5565, Instron, Japan). The data (n=5) were analyzed by an ANOVA/Tukey's test (a=0.05). Results: The bending strengths [N, Mean(SD)] of specimens with and without wires were: Palapress vario, 53.35(3.20) and 37.56(4.85); Acron, 52.27(9.51) and 34.42(2.39); and Acron MC: 63.65(13.47) and 42.86(4.49). There were no significant differences in the three resins either with or without wires (p>0.05). In all denture base resins, specimens with wires had significantly greater bending strengths than those without them (p<0.05). Conclusion: Irrespective of the polymerization methods, the bending strengths of denture base resins were increased by the use of reinforcement wires. To prevent damage to acrylic dentures, reinforcement wires should be used in the weakest parts of the denture bases.
    No preview · Conference Paper · Apr 2009
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    ABSTRACT: We report on an electronic structure study of a quasi-two-dimensional Co oxide Ca3Co4O9 with Ca2CoO3 rocksalt layers and CoO2 triangular lattice layers by means of x-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), configuration-interaction calculation on a CoO6 cluster model, and unrestricted Hartree-Fock calculation on a multiband d-p model. The Co 2p XPS spectrum shows that the Co valence of the rocksalt layer is similar to that of the triangular lattice layer. The cluster-model analysis of the Co 2p XPS spectrum indicates that the Co sites of the rocksalt and triangular lattice layers commonly have charge-transfer energy Δ of ∼1.0 eV, d-d Coulomb interaction U of ∼6.5 eV, and transfer integral (pdσ) of ∼−2.3 eV. The Co 3d t2g peak in the valence-band XPS spectrum remains sharp even above the spin-state transition temperature at ∼380 K, indicating that the spin-state transition is different from the low-spin to intermediate-spin or high-spin transitions in perovskite LaCoO3. The line shape of the UPS spectrum near the Fermi level can be reproduced by the combination of unrestricted Hartree-Fock results for the charge-ordered insulating (COI) and paramagnetic metallic (PM) states. The analysis shows that the phase separation between the COI and PM states plays important roles in Ca3Co4O9.
    No preview · Article · Dec 2008 · Physical review. B, Condensed matter
  • T. Chikuma · K. Shiba · K. Makita · Y. Suzuki · T. Ohami · N. Baba
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    ABSTRACT: We have developed a 43-Gb/s differential receiver module for RZ-DPSK. A wide bandwidth of 42 GHz and a high transimpedance gain of 58 dBOmega were achieved.
    No preview · Article · Jan 2008
  • M. Hatatani · Y. Suzuki · N. Miyamoto
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    ABSTRACT: Current perpendicular to plane (CPP)-type heads having various magnetic shield shapes were fabricated, and their medium signal-to-noise ratios (SNRs) and micro-track profiles (MTPs) were measured. To find out how to improve the sharpness of an MTP, we calculated the relationship between a magnetic read width (MRW) and a magnetic shield shape and a shield-to-shield gap spacing (Gs). In our calculation based on the reciprocity principle, a nonuniform magnetic potential reflecting the sensitivity in the free layer was introduced to give a precise MTP. The calculation indicates that a narrow Gs and a parallel shield are effective in obtaining a sharper MTP. The calculation results were also confirmed by experimental data. Measurement using a perpendicular medium shows that the medium SNR gets higher as the MTP becomes sharper. Thus, CPP-type heads with a sharp MTP have an advantage in getting good SNR performance
    No preview · Article · Jul 2007 · IEEE Transactions on Magnetics
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    ABSTRACT: We demonstrate 30-Gb/s transmission using 1.1 μm-range VCSELs based on InGaAs/GaAs quantum wells, back-illuminated InGaAs PDs, and TIAs (InP-HBT). Error-free 30-Gbps transmission with 100 m-MMFs (GI32) is achieved for the first time.
    No preview · Conference Paper · Jun 2007

Publication Stats

487 Citations
39.65 Total Impact Points

Institutions

  • 2011
    • National Institute of Public Health
      Saitama, Saitama, Japan
    • Osaka University
      • Graduate School of Engineering
      Suika, Ōsaka, Japan
  • 2003-2011
    • Tokyo Metropolitan University
      • Department of Electrical and Electronic Engineering
      Edo, Tōkyō, Japan
  • 2001-2010
    • Tsurumi University
      • Department of Removable Prosthodontics
      Yokohama, Kanagawa, Japan
  • 2003-2008
    • Tohoku University
      • • Department of Applied Physics
      • • Research Institute of Electrical Communication
      Sendai, Kagoshima-ken, Japan
  • 2004
    • Hirosaki University
      • School of Health Sciences
      Khirosaki, Aomori, Japan
    • RIKEN
      Вако, Saitama, Japan
  • 1998-2004
    • NEC Corporation
      Edo, Tōkyō, Japan
  • 1999-2001
    • The Jikei University School of Medicine
      • Department of Public Health and Environmental Medicine
      Edo, Tokyo, Japan
    • University of Tsukuba
      Tsukuba, Ibaraki, Japan