Growth of Nitrogen-Doped MgxZn1−xO for Use in Visible Rejection Photodetectors

A. Nakamura,T. Aoshima,T. Hayashi,S. Gangil,J. Temmyo,A. Navarro,J. Pereiro,E. Munoz 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

Improvement in the Schottky behavior of metal (Au) contacts with Mg0.01Zn0.99O and Mg0.01Zn0.99O:N thin films were observed by treating the films with hydrogen peroxide (H2O2) (dipping of samples in H2O2 at 100 ℃ for 3 min). Contacts formed on untreated film showed Ohmic behavior in the current-voltage (I-V ) measurements. The H2O2 treatment led to a smooth surface morphology for the films and resulted in Schottky contact of Au fabricated on the treated films with barrier heights of 0.82 ∽ 0.85 eV. The absolute current density at a reverse bias of 3 V was 1 ∽ 6 × 10−6 A/cm2 for Au contacts on H2O2-treated films. The treated films showed lower electron concentration than the untreated films due to removal of the relatively high conducting top layers of the thin films. A metal-semiconductor-metal (MSM) detector was fabricated using a Mg0.05Zn0.95O:N film and was characterized for its spectral response.

Growth of $GdVO_4$ composite single-crystal rods by the double-die edge-defined film-fed growth technique

Furukawa, Y.,Matsukura, M.,Nakamura, O.,Miyamoto, A. The Korea Association of Crystal Growth 2008 韓國結晶成長學會誌 Vol.18 No.1

The growth of composite-structured Nd:$GdVO_4$ single crystal rods by the double die EFG method is reported. Two crucibles are combined with an outer and inner die for ascending of different melt. The composite-structured Nd:$GdVO_4$ single crystal rods with a length of 50 mm and an outer diameter of 5 mm including of inner Nd-doped core region with diameter 3 mm were grown successfully. Nd distribution in the, radial direction has graded profile from result of EPMA. Absorption coefficient in the core region at 808 nm was $42cm^{-1}$. Finally, we demonstrated the laser oscillation using our composite crystal and 2-W output was obtained.

Growth of GdVO4 composite single-crystal rods by the double-die edge-defined film-fed growth technique

Y. Furukawa,M. Matsukura,O. Nakamura,A. Miyamoto 한국결정성장학회 2008 韓國結晶成長學會誌 Vol.18 No.1

The growth of composite-structured Nd : GdVO4 single crystal rods by the double die EFG method is reported. Two crucibles are combined with an outer and inner die for ascending of different melt. The composite-structured Nd : GdVO4 single crystal rods with a length of 50 mm and an outer diameter of 5 mm including of inner Nd-doped core region with diameter 3 mm were grown successfully. Nd distribution in the radial direction has graded profile from result of EPMA. Absorption coefficient in the core region at 808 nm was 42 cm−1 . Finally, we demonstrated the laser oscillation using our composite crystal and 2-W output was obtained.

Phase Diagram and Transport Properties of Y1−xNdxCo2 Pseudo-binary Alloys

A. T. Burkov,M. Takeda,A. Teruya,S. Watanabe,Y. Hiranaka,A. Nakamura,M. Hedo,T. Nakama,K. Yagasaki,Y. Takaesu,K. Uchima,Y. Uwatoko 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12

The electrical resistivity and the thermopower S of pseudo-binary Y1−xNdxCo2 alloys have beenmeasured at temperatures from 2 to 300 K under pressures up to 3.5 GPa. NdCo2 is a ferromagnetwith a Curie temperature TC of 98 K. In the ferromagnetic phase, it undergoes a 4f spin-reorientationtransition at TR = 40 K. At this transition, the easy direction of 4f magnetization is changed from[100] at temperatures above TR to [110] below TR. The system phase diagram TC(x, P) and TR(x, P)is inferred from the temperature dependencies of the electrical resistivity and the thermopower. The Curie temperature of the alloys, TC decreases with decreasing Nd concentration x and vanishesaround xc = 0.3. Above xc, the Curie temperature decreases with increasing pressure. The spinreorientationtemperature weakly depends on the composition and on the pressure until it mergeswith TC. There is a large region of the phase diagram, partly overlapping with the ferromagneticphase, where the cobalt 3d electron system is non-uniformly magnetized due to spatial fluctuationsof the 4f-3d exchange field related to a random distribution of Nd 4f magnetic moments over the Rsublattice. In this region, large static 3d magnetic fluctuations govern the electronic transport.

Characterization of an Intense Laser-Produced Preformed Plasma for Proton Generation

A Sagisaka,A. Noda,A. Fukumi,A. Yogo,A. S. Pirozhkov,H. Daido,K. Nemoto,K. Ogura,M. Nishiuchi,M. Mori,M. Kado,S. Orimo,S. Nakamura,T. Nayuki,T. Shirai,T. Fujii,Y. Oishi,Y. Hayashi,Y. Iwashita,Z. Li 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.I

High-energy protons are generated with a 3-μm-thick tantalum target irradiated with a highintensity laser under the preformed plasma condition. We observe the electron density distributions of preformed plasmas with two-color probe beams as interferometers. The preformed plasma at the front side of the target is generated by pre-pulses of a high-intensity Ti:sapphire laser. In this preformed plasma condition, the maximum proton enegy is 900 keV. The half angle of the generated proton beam (>500 keV) is about 10.

Anti-inflammatory effects of methyl ursolate obtained from a chemically derived crude extract of apple peels: potential use in rheumatoid arthritis

Tatiana A. Pa´dua,Bianca S. S. C. de Abreu,Thadeu E. M. M. Costa,Marcos J. Nakamura,Lı´gia M. M,Antonio C. Siani,Elaine C. Rosas 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.11

Ursolic acid (UA), a pentacyclic triterpene acidfound in apple peels (Malus domestica, Borkh, Rosaceae),has a large spectrum of pharmacological effects. However,the vegetal matrix usually produces highly viscous andpoorly soluble extracts that hamper the isolation of thiscompound. To overcome this problem, the crude EtOH–AcOEt extract of commercial apple peels was exhaustivelytreated with diazomethane, after which methyl ursolate(MU) was purified by column chromatography and characterizedspectrometrically. The anti-inflammatory effectsof UA and MU (50 mg/kg) were analyzed by zymosaninducedpaw edema, pleurisy and in an experimentalarthritis model. After 4 h of treatment with UA and MU,paw edema was reduced by 46 and 44 %, respectively. Both UA and MU inhibited protein extravasation into thethoracic cavity; tibio-femoral edema by 40 and 48 %,respectively; and leukocyte influx into the synovial cavityafter 6 h by 52 and 73 %, respectively. Additionally, bothUA and MU decreased the levels of mediators related tosynovial inflammation, such as KC/CXCL-1 levels by 95and 90 %, TNF-a levels by 76 and 71 %, and IL-1b levelsby 57 and 53 %, respectively. Both the compounds wereequally effective when assayed in different inflammatorymodels, including experimental arthritis. Hence, MU maybe considered to be a useful anti-inflammatory derivative toovercome the inherent poor solubility of UA for formulatingpharmaceutical products.

Boolean Approach to Dichotomic Quantum Measurement Theories

K. Nagata,T. Nakamura,J. Batle,S. Abdalla,A. Farouk 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.3

Recently, a new measurement theory based on truth values was proposed by Nagata and Nakamura [Int. J. Theor. Phys. 55, 3616 (2016)], that is, a theory where the results of measurements are either 0 or 1. The standard measurement theory accepts a hidden variable model for a single Pauli observable. Hence, we can introduce a classical probability space for the measurement theory in this particular case. Additionally, we discuss in the present contribution the fact that projective measurement theories (the results of which are either +1 or −1) imply the Bell, Kochen, and Specker (BKS) paradox for a single Pauli observable. To justify our assertion, we present the BKS theorem in almost all the two-dimensional states by using a projective measurement theory. As an example, we present the BKS theorem in two-dimensions with white noise. Our discussion provides new insight into the quantum measurement problem by using this measurement theory based on the truth values.

Effect of Partial Magnetic Order on Resistivity and Thermopower of Ho(Co1−xAlx)2 Alloys

T. Nakama,C. Zukeran,A. Nakamura,A. Teruya,S. Hirakawa,S. Watanabe,Y. Hiranaka,M. Takeda,M. Hedo,K. Yagasaki,Y. Takaesu,K. Uchima,A. T. Burkov 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3

The electrical resistivity and the thermopower S of Ho(Co1−xAlx)2 alloys (x = 0 to 0.2) weremeasured at temperatures from 2 K to 300 K in magnetic fields up to 10 T. While (T) and S(T)of pure HoCo2 reveal abrupt changes at the magnetic ordering temperature TC, indicating a firstordertransition, the temperature variations of both properties across the ordering temperature inHo(Co1−xAlx)2 alloys clearly show that the type of magnetic transition changes under substitutionof Al for Co from first order to second order around x 0.06. (T) of the Al-substituted samples (x= 0.15 and 0.2) has a very unusual variation at temperatures below TC: in contrast to the expectedand usually-observed decrease of (T), the resistivity of Ho(Co1−xAlx)2 alloys (x = 0.15 and 0.2)increases at temperatures below TC. Moreover, the magnetoresistance of these alloys is positivearound TC; this is also in a sharp contrast to the usually observed negative magnetoresistance. We show that the anomalous resistivity and magnetoresistance in these alloys are related to themetamagnetic instability of the Co 3d subsystem and to the fluctuating local magnetic susceptibilitydue to atomic substitution. Due to this fluctuating local magnetic susceptibility, the uniformexchange field of 4f moments induces a non-uniform polarization of the 3d system, with staticspatial fluctuations of the local magnetization. This static magnetic disorder gives an additionalcontribution (m) to the electrical resistance in the alloys at temperatures below TC. The degreeof this disorder changes with decreasing temperature, resulting in specific variation of m withtemperature.

Neutron occupancy of the 0 _{d 5 / 2} orbital and the N = 16 shell closure in ²⁴O

Tshoo, K.,Satou, Y.,Bertulani, C.A.,Bhang, H.,Choi, S.,Nakamura, T.,Kondo, Y.,Deguchi, S.,Kawada, Y.,Nakayama, Y.,Tanaka, K.N.,Tanaka, N.,Togano, Y.,Kobayashi, N.,Aoi, N.,Ishihara, M.,Motobayashi, T. Elsevier 2014 Physics letters: B Vol.739 No.-

<P><B>Abstract</B></P> <P>One-neutron knockout from <SUP>24</SUP>O leading to the first excited state in <SUP>23</SUP>O has been measured for a proton target at a beam energy of 62 MeV/nucleon. The decay energy spectrum of the neutron unbound state of <SUP>23</SUP>O was reconstructed from the measured four momenta of the <SUP>22</SUP>O fragment and emitted neutron. A sharp peak was found at <SUB> E decay </SUB> = 50 ± 3 keV , corresponding to an excited state in <SUP>23</SUP>O at 2.78 ± 0.11 MeV , as observed in previous measurements. The longitudinal momentum distribution for this state was consistent with <I>d</I>-wave neutron knockout, providing support for a <SUP> J π </SUP> assignment of 5 / <SUP> 2 + </SUP> . The associated spectroscopic factor was deduced to be <SUP> C 2 </SUP> S ( 0 <SUB> d 5 / 2 </SUB> ) = 4.1 ± 0.4 by comparing the measured cross section ( σ − 1 n exp = 61 ± 6 mb ) with a distorted wave impulse approximation calculation. Such a large occupancy for the neutron 0 <SUB> d 5 / 2 </SUB> orbital is in line with the N = 16 shell closure in <SUP>24</SUP>O.</P>

Quick Detection of Firefly Luciferase Gene Expression in Live Developing Bovine Embryos by Photoncounting

Nakamura, A.,Okumura, J.,Muramatsu, T. Asian Australasian Association of Animal Productio 1998 Animal Bioscience Vol.11 No.5

The present study was designed, fIrst to develop the new methodology to measure the bioluminescence activity easily in live developing bovine embryos by photoncounting, and secondly to compare the expression efficiency of four luciferase reporter genes in bovine embryos at four- to 16-cell stages. In experiment 1, equimolar pSVlacZ and pSVEluc were microinjected into the pronucleus of fertilized bovine oocytes. At 2 days after micro injection, bioluminescence activity of these embryos was measured by photoncounting with a luminometer for 1 min, and lacZ gene expression in the same embryos was assayed by X-gal staining. All the luciferase-positive oocytes showed some bacterial ${\beta}$-galactosidase activity irrespective of the intensity. In experiment 2, four firefly luciferase genes (pTKEluc, pTK6WEluc, pSVEluc and pMiwluc) were introduced by micro injection, and the injected embryos were cultured for the following 2 days. Detection of the luciferase gene expression was done by photoncounting at 5 to 55 min. Over the measurement period, the luciferase activity was almost constant irrespective of the transgenes microinjected. The luciferase activity and expression efficiency at 2 days after microinjection were not significantly affected by the difference in the microinjected transgenes. The present results demonstrated that the bioluminescence activity in live developing bovine embryos could be measured quickly by photoncounting.