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Search Results: 1 - 10 of 2176 matches for " Makoto Hibino "
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Effect of Nitrite Ions on Steel Corrosion Induced by Chloride or Sulfate Ions
Zhonglu Cao,Makoto Hibino,Hiroki Goda
International Journal of Corrosion , 2013, DOI: 10.1155/2013/853730
Abstract: The influence of nitrite concentration on the corrosion of steel immersed in three simulated pH environments containing chloride ions or sulfate ions has been investigated by comparing and analyzing the change of half-cell potential, the change of threshold level of or , the change of threshold level of / or / mole ratio, and the changes of anodic/cathodic polarization curves and Stern-Geary constant . The corrosivity of chloride ions against sulfate ions also has been discussed in pH 12.6, pH 10.3, and pH 8.1 environments containing 0, 0.053, and 0.2?mol/L , respectively. 1. Introduction The corrosion of reinforcing steel in concrete has become one of the most severe deterioration mechanisms in concrete structures. It is generally accepted that due to the high alkalinity of cement hydration products, a protective layer of iron oxides is formed on the surface of steel, which provides adequate corrosion resistance. However, with the penetration of chloride, sulfate, and carbon dioxide and the appearance of concrete cracking, this protective layer becomes unstable and corrosion initials. As one of the methods is to prevent steel corrosion, nitrite-based corrosion inhibitors, irrespective of being directly added into concrete during the mixing process or penetrating into concrete by the surface-applied remedial treatment, have been widely investigated in chloride-contaminated concrete [1–3], carbonated concrete [4–6], and cracked concrete [7, 8], and their inhibiting efficiencies also have been checked in simulated concrete pore solution, such as in highly alkaline solution [9–12], carbonated solution [12–14], and neutral and acid solution [12, 15]. Most of these results confirm the effectiveness of nitrite in increasing the chloride threshold level, delaying the onset of corrosion, and reducing the corrosion rate once the corrosion was initiated, but there is no general consensus on the / mole ratio above that the preservation of the passive state can be ensured; suggested values for this threshold range from 0.11 to 1.0 in concrete and from 0.07 to greater than 2 in simulated pore solution. This difference in the threshold level of / mole ratio obtained from various literatures might be due to the way of determining the concentrations of chloride and nitrite in concrete (free ions and total ions, etc.), the different qualities of mortar and concrete used in the experiments, the different components of simulated pore solution, and the different surface topographies and compositions of the steel. Comparing and analyzing these literatures, the authors find
Effect of Water-Cement Ratio on the Macrocell Polarization Behavior of Reinforcing Steel
Zhonglu Cao,Makoto Hibino,Hiroki Goda
Journal of Engineering , 2014, DOI: 10.1155/2014/925410
Abstract: The effect of water-cement ratio on the macrocell polarization behavior of reinforcing steel embedded in cement mortars was investigated by comparing and analyzing the macrocell polarization ratios and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was also analyzed, and the mechanism of macrocell polarization affected by water-cement ratio was proposed. The results indicated that the water-cement ratios had little impact on the macrocell polarization ratios of cathode and anode. The lower water-cement ratio could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the cathode and anode. 1. Introduction The water-cement ratio (W/C ratio) is one of the important parameters affecting the long-term properties of reinforced concrete. For cement pastes hydrated to the same degree, as the water-cement ratio decreases, the permeability of reinforced concrete decreases as well. The permeability of reinforced concrete is a critical factor limiting the penetration of chloride and the diffusion of carbon dioxide, oxygen, and other aggressive agents and therefore plays an important role in controlling the microcell and macrocell corrosion behaviors of reinforcing steel. According to the study of Arya and Vassie [1], for the same area ratio of cathode to anode, a lower water-cement ratio, and hence lower permeability, could decrease the macrocell current flowing between cathodic steel and anodic steel. This lower current obtained from the lower permeability mix could probably be explained by the higher resistance of concrete and the lower transport rate of oxygen and ferrous ions, producing restrictions to the cathode and anode reaction kinetics. Similar results could be confirmed by the study of Vedalakshmi et al. [2], Hansson et al. [3], and Ohno et al. [4–7]. The results of Raupach [8] indicated that a reduction of the water-cement ratio from 0.6 to 0.5 yielded a further reduction in steel mass loss in the crack zone. This influence was especially pronounced after 24 weeks and then became much smaller after one year, which might be explained by the fact that the period up to depassivation was prolonged by a reduction of the water-cement ratio. However, after the onset of corrosion, the water-cement ratio had only a negligible influence. All these studies as mentioned above only investigated the effect of water-cement ratio on the magnitude of macrocell current and did not
Hydrogen storage with titanium-functionalized graphene
Torge Mashoff,Makoto Takamura,Shinichi Tanabe,Hiroki Hibino,Fabio Beltram,Stefan Heun
Physics , 2013, DOI: 10.1063/1.4812830
Abstract: We report on hydrogen adsorption and desorption on titanium-covered graphene in order to test theoretical proposals to use of graphene functionalized with metal atoms for hydrogen storage. At room temperature titanium islands grow with an average diameter of about 10 nm. Samples were then loaded with hydrogen, and its desorption kinetics was studied by thermal desorption spectroscopy. We observe the desorption of hydrogen in the temperature range between 400K and 700 K. Our results demonstrate the stability of hydrogen binding at room temperature and show that hydrogen desorbs at moderate temperatures in line with what required for practical hydrogen-storage applications.
Correlation between morphology and transport properties of quasi-free-standing monolayer graphene
Yuya Murata,Torge Mashoff,Makoto Takamura,Shinichi Tanabe,Hiroki Hibino,Fabio Beltram,Stefan Heun
Physics , 2014, DOI: 10.1063/1.4902988
Abstract: We investigate the morphology of quasi-free-standing monolayer graphene (QFMLG) formed at several temperatures by hydrogen intercalation and discuss its relationship with transport properties. Features corresponding to incomplete hydrogen intercalation at the graphene-substrate interface are observed by scanning tunneling microscopy on QFMLG formed at 600 and 800{\deg}C. They contribute to carrier scattering as charged impurities. Voids in the SiC substrate and wrinkling of graphene appear at 1000{\deg}C, and they decrease the carrier mobility significantly.
Tuning of quantum interference in top-gated graphene on SiC
Andrea Iagallo,Shinichi Tanabe,Stefano Roddaro,Makoto Takamura,Hiroki Hibino,Stefan Heun
Physics , 2013, DOI: 10.1103/PhysRevB.88.235406
Abstract: We report on quantum-interference measurements in top-gated Hall bars of monolayer graphene epitaxially grown on the Si face of SiC, in which the transition from negative to positive magnetoresistance was achieved varying temperature and charge density. We perform a systematic study of the quantum corrections to the magnetoresistance due to quantum interference of quasiparticles and electron-electron interaction. We analyze the contribution of the different scattering mechanisms affecting the magnetotransport in the $-2.0 \times 10^{10}$ cm$^{-2}$ to $3.75 \times 10^{11}$ cm$^{-2}$ density region and find a significant influence of the charge density on the intravalley scattering time. Furthermore, we observe a modulation of the electron-electron interaction with charge density not accounted for by present theory. Our results clarify the role of quantum transport in SiC-based devices, which will be relevant in the development of a graphene-based technology for coherent electronics.
Bilayer-induced asymmetric quantum Hall effect in epitaxial graphene
Andrea Iagallo,Shinichi Tanabe,Stefano Roddaro,Makoto Takamura,Yoshiaki Sekine,Hiroki Hibino,Vaidotas Miseikis,Camilla Coletti,Vincenzo Piazza,Fabio Beltram,Stefan Heun
Physics , 2014, DOI: 10.1088/0268-1242/30/5/055007
Abstract: The transport properties of epitaxial graphene on SiC(0001) at quantizing magnetic fields are investigated. Devices patterned perpendicularly to SiC terraces clearly exhibit bilayer inclusions distributed along the substrate step edges. We show that the transport properties in the quantum Hall regime are heavily affected by the presence of bilayer inclusions, and observe a significant departure from the conventional quantum Hall characteristics. A quantitative model involving enhanced inter-channel scattering mediated by the presence of bilayer inclusions is presented that successfully explains the observed symmetry properties.
A novel third complement component C3 gene of Ciona intestinalis expressed in the endoderm at the early developmental stages
T Hibino,M Nonaka
Invertebrate Survival Journal , 2013,
Abstract: The third complement component (C3) in ascidian was reported to function as an opsonin to enhance phagocytosis and as a chemotactic factor for phagocytes, indicating that ascidian C3 works in mesodermal cavity as a humoral factor like vertebrate C3s. In the basal Eumetazoa, Cnidaria lacking mesodermal tissues, C3 was reported to work in an endodermal cavity. Evolution of structure and function of C3 is still to be clarified. Here we report the identification of the third C3 gene, CiC3-3, in the genome of an ascidian, Ciona intestinalis. Phylogenetic analysis using the entire amino acid sequences of Eumetazoan C3s indicated that CiC3-3 possess a closer relationship to vertebrate C3, C4 and C5 than other ascidian C3s. Although CiC3-3 retained the α-β processing site and 6 cysteine residues in the C3a region, it lacked the intra-molecular thioester bond and the catalytic histidine residue. Instead, CiC3-3 had a unique insertion of about 70 residues long Lys/Arg-rich sequence. CiC3-3 was expressed highly in the embryonic stages, but little in the adult in contradistinction to CiC3-1 and CiC3-2. The expression of CiC3-3 in early embryonic stages was restricted to endoderm similar to cnidarian C3s. Thus, the ascidian complement system could represent a unique evolutionary stage sharing a primitive endodermal function with Cnidaria, and newly developed humoral function with vertebrates.
Ultra-High Molecular Weight Polyethylene Tape Applied for Distal Humeral Condyle Fracture around Total Elbow Arthroplasty in Patients with Rheumatoid Arthritis: Report of Two Cases  [PDF]
Norio Yamamoto, Mitsuhiko Takahashi, Naohito Hibino, Koichi Sairyo
Open Journal of Orthopedics (OJO) , 2015, DOI: 10.4236/ojo.2015.59038
Abstract: Managing fractures of distal humerus in patients with rheumatoid arthritis (RA) is technically challenging. Total elbow arthroplasty (TEA) is one of the treatment options for these fractures. While elbow motion is largely regained by TEA, comminuted condyle fragments are often ignored. Although numerous approaches for repair of condylar fragments around TEA are described, any universal fixation strategy for these fractures has not been established. This report describes, for the first time, application of an ultra-high molecular weight polyethylene (UHMWPE) tape for the treatment of distal humerus fracture in 2 patients with rheumatic elbow arthropathy. The post-operative clinical courses were good. Radiographs showed bony union of the condylar fragments without loosening in two cases. Because of its flat configuration, softness, and flexibility, UHMWPE tape is a promising material for stabilizing fracture of the distal humerus associated with TEA.
Transcutaneous Electrical Nerve Stimulation on the PC-5 and PC-6 Points Alleviated Hypotension after Epidural Anaesthesia, Depending on the Stimulus Frequency
Young-Chang P. Arai,Akihiro Ito,Kenji Ohshima,Soki Hibino,Sinnosuke Niwa,Jun Kawanishi,Hiroki Numanami,Yoshikazu Sakakima,Shouji Mizuno,Yusuke Tawada,Yuki Maruyama,Jun Sato,Makoto Nishihara,Shinsuke Inoue,Takahiro Ushida
Evidence-Based Complementary and Alternative Medicine , 2012, DOI: 10.1155/2012/727121
Abstract: Neuraxial blockade causes arterial hypotension. Transcutaneous electrical nerve stimulation (TENS) at the Neiguan (PC-6) and Jianshi (PC-5) reduces the severity of hypotension after spinal anaesthesia, but did not clarify the optimal stimulus frequency. We hypothesized that the stimulus frequency of TENS at the PC-6 and PC-5 points would influence the severity of hypotension after epidural anaesthesia. 65 ASA I or II male patients presenting for inguinal hernia repair were randomized to five groups: the control group received no treatment; the 2 Hz, 10 Hz, 20 Hz, and 40 Hz groups received TENS at a frequency of 2 Hz, 10 Hz, 20 Hz, and 40 Hz, respectively. The lowest SBP was significantly higher in the 40 Hz group [the control, 84 (74–110) mmHg; the 2 Hz, 96 (62–116) mmHg; the 10 Hz, 100 (68–110) mmHg; the 20 Hz, 96 (64–115) mmHg; the 40 Hz, 104 (75–140) mmHg: =0.004]. Significantly less patients experienced hypotension in the 40 Hz group [the control, 78%; the 2 Hz, 43%; the 10 Hz, 38%; the 20 Hz, 38%; the 40 Hz, 8%: =0.008]. TENS on the PC-6 and PC-5 points reduced the severity and incidence of hypotension after epidural anaesthesia, depending on the stimulus frequency.
On Canard Homoclinic of a Liénard Perturbation System  [PDF]
Makoto Hayashi
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.210170
Abstract: The classification on the orbits of some Liénard perturbation system with several parameters, which is relation to the example in [1] or [2], is discussed. The conditions for the parameters in order that the system has a unique limit cycle, homoclinic orbits, canards or the unique equilibrium point is globally asymptotic stable are given. The methods in our previous papers are used for the proofs.
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