Fabrication and electrical properties of sintered bodies composed of Mn(1.75-1.25X)Co2.5XNi1.25(1−X)O4 (0 ≤ X ≤ 0.6) with a cubic spinel structure

Takashi Yokoyama,Masaru Nakamura,Junichi Tatami,Toru Wakihara,Takeshi Meguro 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.5

Preparation of cubic spinel-type oxides, Mn(1.75−1.25X)Co2.5XNi1.25(1−X)O4 (0 ≤X≤ 0.6), and their electrical properties were investigated. The starting oxides, containing metals with a prescribed molar ratio, were heated to 1400℃ and held for 3 h in argon. The sintered bodies were cooled to 800 oC and then oxidized for 48 h in air to convert them into a cubic spinel structure. The electrical conductivities of the sintered bodies were confirmed to increase exponentially with an increase in the temperature, indicating that they have intrinsic NTC thermistor characteristics. In the region of 0 ≤ X≤ 0.4, the electrical conductivity increased with an increase in X and decreased with an increase in X in the region of 0.4 < X ≤ 0.6. The concentration of Mn4+ in the octahedral sites of the spinel structure was considered to be larger than that of Mn3+ because the sintered bodies were n-type semiconducting. The electrical conduction of the oxides prepared in this study was concluded to be controlled by a small polaron hopping mechanism. Preparation of cubic spinel-type oxides, Mn(1.75−1.25X)Co2.5XNi1.25(1−X)O4 (0 ≤X≤ 0.6), and their electrical properties were investigated. The starting oxides, containing metals with a prescribed molar ratio, were heated to 1400℃ and held for 3 h in argon. The sintered bodies were cooled to 800 oC and then oxidized for 48 h in air to convert them into a cubic spinel structure. The electrical conductivities of the sintered bodies were confirmed to increase exponentially with an increase in the temperature, indicating that they have intrinsic NTC thermistor characteristics. In the region of 0 ≤ X≤ 0.4, the electrical conductivity increased with an increase in X and decreased with an increase in X in the region of 0.4 < X ≤ 0.6. The concentration of Mn4+ in the octahedral sites of the spinel structure was considered to be larger than that of Mn3+ because the sintered bodies were n-type semiconducting. The electrical conduction of the oxides prepared in this study was concluded to be controlled by a small polaron hopping mechanism.

Preparation and electrical properties of sintered bodies composed of Mn(1 + 0.5X) FeNi(1-0.5X)O4 (0 ≤ X ≤ 1.00) with cubic spinel structure

Takashi Yokoyama 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.5

The preparation and electrical properties of sintered bodies consisting of monophase cubic spinel oxides, Mn(1 + 0.5X)FeNi(1-0.5X)O4 (0 ≤ X ≤ 1.00), were investigated. Sintered bodies composed of monophase cubic spinel structure were prepared through heat treatment at 1000 o C for oxidization after sintering at 1400 o C in Ar. The required time for oxidization exceeded 48 h for specimens with X = 0 to 0.375 and more than 96 h for those with X = 0.50 to 1.00. Electrical conduction (σ) and Seebeck potential (Qe) were measured using rectangular bars cut from sintered pellets. The electrical characteristics were determined based on the change of cation distribution related to the disproportionation of Mn ions. We concluded that the electrical conduction of sintered bodies is controlled by a small polaron hopping mechanism.

Chromium(IV)–Peroxo Complex Formation and Its Nitric Oxide Dioxygenase Reactivity

Yokoyama, Atsutoshi,Han, Jung Eun,Cho, Jaeheung,Kubo, Minoru,Ogura, Takashi,Siegler, Maxime A.,Karlin, Kenneth D.,Nam, Wonwoo American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.37

<P>The O<SUB>2</SUB> and NO reactivity of a Cr(II) complex bearing a 12-membered tetraazamacrocyclic <I>N</I>-tetramethylated cyclam (TMC) ligand, [Cr<SUP>II</SUP>(12-TMC)(Cl)]<SUP>+</SUP> (<B>1</B>), and the NO reactivity of its peroxo derivative, [Cr<SUP>IV</SUP>(12-TMC)(O<SUB>2</SUB>)(Cl)]<SUP>+</SUP> (<B>2</B>), are described. By contrast to the previously reported Cr(III)–superoxo complex, [Cr<SUP>III</SUP>(14-TMC)(O<SUB>2</SUB>)(Cl)]<SUP>+</SUP>, the Cr(IV)–peroxo complex <B>2</B> is formed in the reaction of <B>1</B> and O<SUB>2</SUB>. Full spectroscopic and X-ray analysis revealed that <B>2</B> possesses side-on η<SUP>2</SUP>-peroxo ligation. The quantitative reaction of <B>2</B> with NO affords a reduction in Cr oxidation state, producing a Cr(III)–nitrato complex, [Cr<SUP>III</SUP>(12-TMC)(NO<SUB>3</SUB>)(Cl)]<SUP>+</SUP> (<B>3</B>). The latter is suggested to form via a Cr(III)–peroxynitrite intermediate. [Cr<SUP>II</SUP>(12-TMC)(NO)(Cl)]<SUP>+</SUP> (<B>4</B>), a Cr(II)–nitrosyl complex derived from <B>1</B> and NO, could also be synthesized; however, it does not react with O<SUB>2</SUB>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-37/ja307384e/production/images/medium/ja-2012-07384e_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja307384e'>ACS Electronic Supporting Info</A></P>

Japan and U. K. Collaboration for Mutsu Bay sea surface temperature validation experiment by satellite data

Yokoyama, Ryuzo,Tamba, Sumio,Soma, Takashi,Jones, David Llewellyn,Parkes, Isabelle,Dunlon, Craig 대한원격탐사학회 1996 International Symposium on Remote Sensing Vol.12 No.1

The first Mutsu Bay Sea Surface Temperature Validation Experiment (MUBEX'95), which is joint research and observation experiment together with United Kingdom and Japan, has performed during the period 20th July to 27th August 1995 in Mutsu Bay, northern Honshu, Japan. The joint validation experiment has been planned to continue during three years from 1995. The stated objectives of MUBEX'95 are: (1). To validate the sea surface temperature (SST) observations made by four satellite radiometer systems, which are ERS-1/ATSR-1, ERS-2/ATSR-2, NOAA-12/AVHRR and NOAA-14lAVHRR, (2). To investigate the surface fluxes of heat and momentum and other processes thought to define the radiometric signal measured by infrared radiometry, (3). To investigate the sub pixel temperature and variability of the radiometric SST with reference to the SST at depth.

Sea skin temperature behavior based on thermal infrared camera data during MUBEX observation campaign

Yokoyama, Ryuzo,Tamba, Sumio,Souma, Takashi 대한원격탐사학회 1997 International Symposium on Remote Sensing Vol.13 No.1

MUBEX (MUtsu Bay sea surface temperature validation EXperiment) is a Japan-UK joint research project for accuracy validation of sea surface temperature observed by satellite and investigating into the physical behavior of heat exchange at the ocean surface. In MUBEX observation campaign, sea skin temperature was extensively observed by a thermal infrared camera (TIC). The total number of the image collected in the MUBEX/96 campaign was about 50,000 frames, which provided various aspects of sea skin temperature behaviorism. The distribution pattern of sea skin temperature changes depending upon sun shine, cloud and wind. In this paper, we will introduce the outline of MUBEX and describes the results of early stage of TIC image analyses concerned with sea skin temperature observation.

Endoscopic treatment or balloon-occluded retrograde transvenous obliteration is safe for patients with esophageal/gastric varices in Child-Pugh class C end-stage liver cirrhosis

Keiji Yokoyama,Ryo Yamauchi,Kumiko Shibata,Hiromi Fukuda,Hideo Kunimoto,Kazuhide Takata,Takashi Tanaka,Shinjiro Inomata,Daisuke Morihara,Yasuaki Takeyama,Satoshi Shakado,Shotaro Sakisaka 대한간학회 2019 Clinical and Molecular Hepatology(대한간학회지) Vol.25 No.2

Background/Aims: There is a controversy about the availability of invasive treatment for esophageal/gastric varices in patients with Child-Pugh class C (CP-C) end-stage liver cirrhosis (LC). We have evaluated the validity of invasive treatment with CP-C end-stage LC patients. Methods: The study enrolled 51 patients with CP-C end-stage LC who had undergone invasive treatment. The treatment modalities included endoscopic variceal ligation in 22 patients, endoscopic injection sclerotherapy in 17 patients, and balloon-occluded retrograde transvenous obliteration (BRTO) in 12 patients. We have investigated the overall survival (OS) rates and risk factors that contributed to death within one year after treatment. Results: The OS rate in all patients at one, three, and five years was 72.6%, 30.2%, and 15.1%, respectively. The OS rate in patients who received endoscopic treatment and the BRTO group at one, three, and five years was 67.6%, 28.2% and 14.1% and 90.0%, 36.0% and 18.0%, respectively. The average of Child-Pugh scores (CPS) from before treatment to one month after variceal treatment significantly improved from 10.53 to 10.02 (P=0.003). Three significant factors that contributed to death within one year after treatment included the presence of bleeding varices, high CPS (≥11), and high serum total bilirubin levels (≥4.0 mg/dL). Conclusions: The study demonstrated that patients with a CPS of up to 10 and less than 4.0 mg/dL of serum total bilirubin levels may not have a negative impact on prognosis after invasive treatment for esophageal/gastric varices despite their CP-C end-stage LC.

Photochemistry of <i>Acetabularia</i> RhodopsinII from a Marine Plant, <i>Acetabularia acetabulum</i>

Kikukawa, Takashi,Shimono, Kazumi,Tamogami, Jun,Miyauchi, Seiji,Kim, So Young,Kimura-Someya, Tomomi,Shirouzu, Mikako,Jung, Kwang-Hwan,Yokoyama, Shigeyuki,Kamo, Naoki American ChemicalSociety 2011 Biochemistry Vol.50 No.41

<P><I>Acetabularia</I> rhodopsins are the firstmicrobialrhodopsins discovered in a marine plant organism, <I>Acetabulariaacetabulum</I>. Previously, we expressed <I>Acetabularia</I> rhodopsin II (ARII) by a cell-free system from one of two opsingenes in <I>A. acetabulum</I> cDNA and showed that ARIIis a light-driven proton pump [Wada, T., et al. (2011) <I>J.Mol. Biol.</I><I>411</I>, 986–998]. In thisstudy, the photochemistry of ARII was examined using the flash-photolysistechnique, and data were analyzed using a sequential irreversiblemodel. Five photochemically defined intermediates (P<SUB><I>i</I></SUB>) were sufficient to simulate the data. Noticeably, both P<SUB>3</SUB> and P<SUB>4</SUB> contain an equilibrium mixture of M, N,and O. Using a transparent indium tin oxide electrode, the photoinducedproton transfer was measured over a wide pH range. Analysis of thepH-dependent proton transfer allowed estimation of the p<I>K</I><SUB>a</SUB> values of some amino acid residues. The estimated valueswere 2.6, 5.9 (or 6.3), 8.4, 9.3, 10.5, and 11.3. These values wereassigned as the p<I>K</I><SUB>a</SUB> of Asp81 (Asp85<SUP>BR</SUP>) in the dark, Asp92 (Asp96<SUP>BR</SUP>) at N, Glu199 (Glu204<SUP>BR</SUP>) at M, Glu199 in the dark, an undetermined proton-releasingresidue at the release, and the pH to start denaturation, respectively.Following this analysis, the proton transfer of ARII is discussed.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bichaw/2011/bichaw.2011.50.issue-41/bi2009932/production/images/medium/bi-2011-009932_0006.gif'></P>

Perioperative airway management of a patient with Beckwith-Wiedemann syndrome

Tsukamoto, Masanori,Hitosugi, Takashi,Yokoyama, Takeshi The Korean Dental Society of Anesthsiology 2016 Journal of Dental Anesthesia and Pain Medicine Vol.16 No.4

Airway obstruction in pediatric patients always poses a challenge for anesthesiologists. Beckwith-Wiedemann syndrome causes various abnormalities such as macroglossia and omphalocele. Patients with these abnormalities often need corrective surgeries. Management of difficult airway caused by conditions such as macroglossia in patients with this syndrome could be challenging. We encountered a case of difficult airway in an infant with Beckwith-Wiedemann syndrome. It was predicted that macroglossia might cause difficult ventilation, intubation, and extubation. Preoperative assessment and preparations for difficult airway should be considered.

Flexible laryngeal mask airway management for dental treatment cases associated with difficult intubation

Tsukamoto, Masanori,Hitosugi, Takashi,Yokoyama, Takeshi The Korean Dental Society of Anesthsiology 2017 Journal of Dental Anesthesia and Pain Medicine Vol.17 No.1

Nasotracheal intubation is generally a useful maxillofacial surgery that provides good surgical access for intraoral procedures. When nasotracheal intubation is difficult, laryngeal mask airway (LMA) insertion can be performed, and the flexible $LMA^{TM}$ (FLMA) is also useful for anesthetic management. However, the FLMA provides limited access to the mouth, which restricts the insertion of instrumentation and confines the surgical field available. Here, we present our experience using the FLMA airway management for dental treatment cases involving difficulty with intubation.

Body composition and hemodynamic changes in patients with special needs

Tsukamoto, Masanori,Hitosugi, Takashi,Esaki, Kanako,Yokoyama, Takeshi The Korean Dental Society of Anesthsiology 2016 Journal of Dental Anesthesia and Pain Medicine Vol.16 No.3

Background: Some patients with special needs exhibit intellectual disability, including deficits in cognitive skills and decreased quality of life. The purpose of this study was to retrospectively compare changes in body composition and hemodynamics during general anesthesia in patients with and without special needs. Methods: The backgrounds of patients who underwent oral maxillofacial surgery under general anesthesia were recorded from medical records. Intracellular water (ICW), extracellular water (ECW), stroke volume variation (SVV), and heart rate (HR) were recorded for 3 h after the start of anesthesia. Categorical data were compared using an unpaired t-test, and a P-value of less than 0.05 was regarded as significant. Numerical data were compared using the Bonferroni correction, and a P-value of less than 0.0125 was regarded as significant. Results: A total of 21 patients were included in the study: 10 patients without special needs (non-S-group) and 11 patients with special needs (S-group). There were no significant differences in patients' backgrounds, except with regard to height (P = 0.03). In both groups, ICW and ECW were maintained, although they were lower in the S-group compared to the non-S-group. SVV was maintained in both groups, although it was higher in the S-group than the non-S-group. HR was significantly lower in the S-group 1 h after induction of anesthesia (P < 0.003). Conclusions: Changes in hemodynamics due to body fluid imbalance should be monitored during general anesthesia, especially for patients with special needs.