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Search Results: 1 - 10 of 138577 matches for " K. Akitsu "
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Material Conformity and Bactericidal Characteristics of High-Density Ozone Disinfection in Vinyl Polysiloxane Impression and PMMA Dentistry Fillings  [PDF]
Hiroshi Ohkawa, Tetsuya Akitsu
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.67035

Disinfection was investigated in high-density ozone produced by dielectric barrier discharge under atmospheric pressure. Disinfection was studied on three-dimensional carriers made of hydrophilic vinyl-polysiloxane impression material and granular acrylic resin used for oral surgery. Experimental results indicate disinfection of spore-forming bacteria: Geobacillus stearothermophilus and Bacillus atrophaeus, and selected species of opportunistic pathogens: Aspergillus niger, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Candida albicans.

Simultaneous Multimode Oscillation of Stress-Compensated Cut Quartz Resonator with Narrow-Band Wide Variable-Range Quartz Crystal Oscillator  [PDF]
Tomio Sato, Tetsuya Akitsu
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.613088
Abstract: A multimode-quartz-crystal oscillator was developed to excite stable dual-mode resonance at different frequencies: The oscillation of the 3rd harmonic resonance of the principle C-mode and an additional resonance B-mode of SC-cut crystal. Harmonic combinations of the 3rd and fundamental mode of B-mode with the 3rd harmonics of C-mode are demonstrated. The measurement of the temperature dependence of the oscillation frequency is demonstrated along with the stability determined by root Allan variance. Dependence on the open conductance of the active circuit and the dependence on the coupling capacitors are discussed.
Strip casting using a single roll caster equipped with a scraper
T. Haga,K. Akitsu,K. Kamakura,S. Kumai
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: Purpose: Purpose of this paper is to investigate the ability of a single roll caster equipped with a scraper. The purpose of the development of the single roll caster equipped with a scraper is casting of the strip without centre line segregation and porosity and with sound free solidified surface. The single roll caster can cast the strip without the centre segregation and porosity. However, the conditions of the free solidified surface and the thickness distribution are not sound. The scraper was adopted in order to improve the free solidified surface. Investigation of the effect of the scraper and the properties of the roll cast strip is the purpose of this paper.Design/methodology/approach: A scraper was developed to improve the free solidified surface condition. The scraper scribed the semisolid metal on the free solidified surface to make the free solidified surface flat. The scraper was made from mild-steel-plate, and it was coated by the insulator sheet of 2 mm-thick. The scraper was pushed to free solidified surface by the constant load.Findings: The scraper was very useful to improve the free solidified surface. AA5182 aluminium alloy strip could be cast at the speed up to 40 m/min. There was no centre segregation and porosity. There was no difference between the roll contact surface and the scribed surface. The mechanical properties of the roll cast strip were as same as those of strip made from D.C. cast slab. Hi-content Al-Mg alloy like Al-10 mass%Mg, which cannot be cast into the strip by the twin roll caster without centre segregation, could be cast into the strip without defect.Research limitations/implications: Metal which was investigated was only aluminium alloy. It is not clear that this process is useful to other alloys like steel, copper et. al.Practical implications: This process may be able to be used instead of the D.C. casting and the twin roll casting. Especially, this caster is useful the strip casting of the Al-Mg alloy.Originality/value: The single roll caster equipped with a scraper is original development. This caster may be useful for aluminium and magnesium sheet making companies.
Compatibility of the Active Inductance Double Resonance Quartz Oscillator with Q-MEMS Temperature Sensor  [PDF]
Tetsuya Akitsu, Akira Kudo, Tomio Sato
Engineering (ENG) , 2015, DOI: 10.4236/eng.2015.72005
Abstract: Low-frequency double-resonance quartz crystal oscillator circuit was developed with active inductance aiming the quick start-up in the intermittent operation on the sensor circuit and DC isolation using a Q-MEMS sensing crystal HTS-206. Allan standard deviation indicated 5 × 1012, showing short range stability of the sensor circuit sufficient for the ubiquitous environmental sen sor network.
Start-Up Acceleration of Quartz Crystal Oscillator Using Active Inductance Double Resonance and Embedded Triggering Circuit  [PDF]
Tomio Sato, Akira Kudo, Tetsuya Akitsu
Journal of Sensor Technology (JST) , 2015, DOI: 10.4236/jst.2015.51003
Abstract: Low-frequency double-resonance quartz crystal oscillator was developed with active inductance circuit aiming the start-up of stable oscillation of tuning fork-type quartz crystal resonator at 32.768 kHz within 0.37 ms. The initial oscillation is triggered by a part of crystal oscillator forming a CR oscillator. The negative resistance ranges to 4 MΩ at gmf of 4.1 μA/V. In a limited frequency range, the circuit shows negative reactance Ccci = -3.4 pF equivalent to inductance Lcc = 9.8 H. The Allan standard deviation indicated 10-11 to 10-10, showing high stability comparable to general quartz crystal oscillator.
Observation of Long-Range Vicinal Effect in Chiral Cu(II)-Cr(VI) or Cu(II)-W(VI) Bimetallic Coordination Polymers
Naoshi Hayashi,Takashiro Akitsu
Polymers , 2011, DOI: 10.3390/polym3031029
Abstract: We have prepared some diastereomers of [CuL 2][M 2O 7] (L is 1,2-diaminocyclohexane and its derivatives; M = Cr and W) bimetallic coordination polymers and confirmed their structural similarity and inner electronic states by means of XRD and XAS, respectively. For the first time, we have successfully observed distant vicinal effect of which the chiral source is only chiral organic ligands of [CuL 2] 2+ moieties (acting as ligand complex), while probe bands for solid state CD spectra are charge transfer (CT) bands of [M 2O 7] 2? moieties (achiral complex) with the d 0 electronic configuration. The new concept (interpretation) of this observation will be important for supramolecular chirality of coordination polymers built by ligand complexes.
Takashiro Akitsu,Yuki Endo
Acta Crystallographica Section E , 2009, DOI: 10.1107/s160053680900885x
Abstract: The title compound, [CuPd(CN)4(C4H12N2)2]n, consists of one-dimensional chains. The Cu and Pd atoms are both located on centers of symmetry in an alternating array of [Cu(N-Eten)2]2+ (N-Eten = N-ethylethylenediamine) and [Pd(CN)4]2 units. The Pd—C distances of 1.991 (3) and 1.992 (3) are intermediate values compared with the analogous NiII and PtII complexes [Akitsu & Einaga (2007). Inorg. Chim. Acta, 360, 497–505]. Due to Jahn–Teller effects, the axial Cu—N bond distance of 2.548 (2) is noticeably longer than the equatorial distances [Cu—NH2 = 2.007 (2) and Cu—NHC2H5 = 2.050 (2) ]. There are interchain hybrogen bonds, with N(—H)...N = 3.099(4) .
Some Hybrid Systems of Chiral Schiff Base Zn(II) Complexes and Photochromic Spiropyrans for Environmental Ion Sensing  [PDF]
Takatomo Miura, Takashi Onodera, Shinya Endo, Atsuo Yamazaki, Takashiro Akitsu
American Journal of Analytical Chemistry (AJAC) , 2014, DOI: 10.4236/ajac.2014.512084
Abstract: This is a review article including our recent results and some previous photo functional hybrid system having potential applications for environmental ion sensing. We have prepared several new and known chiral Schiff base Zn(II) complexes and measured (and also calculated) absorption and fluorescence spectra for sole complexes. After assembling hybrid systems with 1,3,3-trime- thylindolino-6’-nitrobenzopyrylospiran (SP) in methanol solutions, we measured spectral changes before and after alternate irradiation of UV and visible light. Intensity of fluorescence spectra for pale yellow Zn(II) complexes (λem = 450 nm, λex = 270 and 360 nm) was quenched by colorless SP (λem = 533 nm, λex = 612 nm). After UV light irradiation to form purple merocyanine (MC), photoisomerization resulted in changes of the intensity of absorption spectra as well as fluorescence spectra. Thus the hybrid systems could successfully act as molecular logic circuit by input (excitation by light) and output (intensity of fluorescence peaks). Moreover, we investigated concentration dependence of doped Zn(II) and Cu(II) ions to confirm quenching of intensity of fluorescence peaks by Zn(II) and Cu(II) MC complexes for metal ion sensing in solutions.
Environmental Dependence of Artifact CD Peaks of Chiral Schiff Base 3d-4f Complexes in Soft Mater PMMA Matrix
Yu Okamoto,Keisuke Nidaira,Takashiro Akitsu
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12106966
Abstract: Four chiral Schiff base binuclear 3d-4f complexes (NdNi, NdCu, GdNi, and GdCu) have been prepared and characterized by means of electronic and CD spectra, IR spectra, magnetic measurements, and X-ray crystallography (NdNi). A so-called artifact peak of solid state CD spectra, which was characteristic of oriented molecules without free molecular rotation, appeared at about 470 nm. Magnetic data of the complexes in the solid state (powder) and in PMMA cast films or solutions indicated that only GdCu preserved molecular structures in various matrixes of soft maters. For the first time, we have used the changes of intensity of artifact CD peaks to detect properties of environmental (media solid state (KBr pellets), PMMA cast films, concentration dependence of PMMA in acetone solutions, and pure acetone solution) for chiral 3d-4f complexes (GdCu). Rigid matrix keeping anisotropic orientation exhibited a decrease in the intensity of the artifact CD peak toward negative values. The present results suggest that solid state artifact CD peaks can be affected by environmental viscosity of a soft mater matrix.
Yoshikazu Aritake,Yoshimasa Watanabe,Takashiro Akitsu
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810007762
Abstract: The title chiral photochromic Schiff base compound, C21H19N3O, was synthesized from (R)-1-phenylethylamine and the salicylaldehyde of an azobenzene derivative. The molecule corresponds to the phenol–imine tautomer, the C=N and N—C bond distances being 1.279 (3) and 1.477 (3) , respectively. An intramolecular O—H...N hydrogen bond occurs. The diazenyl group adopts a trans form with an N=N distance of 1.243 (3) .
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