Development of a prestressed and precast concrete segmental lining

Prestressed & precast concrete segmental lining (P&PCSL) is used for shield tunnels. Its primary feature is that it integrates segments into one ring by introducing prestress in the tunnel circumferential and longitudinal directions. Introducing prestress enables the elimination of bolt joints and reduces the volume of reinforcement, thus reducing the manufacturing cost of precast concrete segments. It also enables quality improvement and labor saving in lining and provides greater adaptability for tunnels with large diameter, where deformation due to dead load is a problem. The P&PCSL has been implemented in three construction projects after undergoing various performance tests and workability verification tests.     

Relationship between apatite-forming ability and mechanical properties of bioactive PMMA-based bone cement modified with calcium salts and alkoxysilane

Polymethylmethacrylate (PMMA)-based bone cement is used for the fixation of artificial joints in orthopaedics. However, the fixation is liable to loosen in the body, because the cement does not bond to living bone. So-called bioactive ceramics bond directly to living bone through the apatite layer formed on their surfaces in the body. We previously revealed that modification using γ-methacryloxypropyltrimethoxysilane (MPS) and water-soluble calcium salts such as calcium acetate and calcium hydroxide was effective for providing the PMMA-based bone cement with apatite-forming ability in a simulated body fluid (SBF, Kokubo solution) that closely reproduces the body environment. However, the effect of the chemical reaction forming the apatite on the mechanical properties of the cements has not been clarified. The present work aimed to investigate this issue from the viewpoint of the interface structure between the apatite and the cement. The surface of the cement modified with calcium acetate and MPS was fully covered with newly formed apatite after soaking in Kokubo solution within 7 days, while half of the surface area of the cement modified with calcium hydroxide and MPS was covered with the apatite. The bending strength of the modified cements decreased after soaking in Kokubo solution. Porous structure was observed in the region about 50–100 μm in depth from the top surface because of release of the Ca²⁺ ions by both modified cements after soaking in Kokubo solution. The decrease in bending strength of the modified cements could be attributed to the formation of the pores. In addition, the pores on the top surfaces of the cements were filled with the newly formed apatite. The apatite formation would be effective not only for bioactivity but also for decreasing the reduction of mechanical strength.     

A flow method with photocatalytic oxidation of dissolved organic matter using a solid-phase (TiO2) reactor followed by amperometric detection of consumed oxygen

A photocatalytic sensor for the determination of chemical oxygen demand (COD) using titanium dioxide, based on the use of a pair of oxygen electrodes and flow injection analysis, is described. The measuring principle is based on the direct determination of the oxygen concentration change resulting from photocataltic oxidation of organic compounds. One of the two oxygen electrodes, the reference oxygen electrode, was utilized to measure the reference signal responding only to oxygen present in the injected samples. Oxygen consumption due to the TiO2-catalyzed photochemical oxidation of organic compounds in samples was monitored with the working oxygen electrode. The COD value of this sensor was calculated as the difference of the currents at reference and working oxygen electrodes, respectively. The operation characteristics of the sensor are demonstrated using artificially treated wastewater as a substrate. The sensor was also applied to the determination of COD in real water samples from dam reservoirs (n = 20) all over Japan. The results were in good agreement with those from the conventional COD methods (i.e., permanganate and dichromate methods).     

Resonance Effect on the Tunneling Reaction: H+H2→H2+H in Solid Hydrogen

The tunneling abstraction reaction: H+H₂H₂+H in -irradiated solid hydrogen has been studied using electron spin resonance (ESR) and electron-nuclear double resonance (ENDOR) spectroscopy and gas-chromatography. The rate constant for the tunneling reaction in solid hydrogen was found to decrease with the increase in the concentration of ortho-H₂ molecules in solid hydrogen. We concluded that the decrease in the rate constant is due to the energy level mismatching between reactant species of H+H₂ trapped and product species of H₂+H trapped in the reverse induced by inhomogeneous intermolecular interactions between ortho-H² molecules in solid hydrogen. This result indicates that resonance effects play an important role in tunneling reactions in solids.     

Effect of rapid sample cooling on efficiency of multiple impurity-atom doping

Shallow and efficient doping of wide band-gap semiconductors has remained one of yet unresolved problems to date. A possible solution to this problem is doping with complexes of a few impurity atoms at a quasi-equilibrium state, which is introduced by controlled cooling of a sample after doping. In this work, (1) we first define a global and quasi-equilibria of our interest based on a simple thermodynamic model for a doped crystal, and then (2) we discuss how the cooling rate affects the probability of impurity-complex formation at a quasi-equilibrium as defined. Our main message is that one should design impurity complexes as small in size as possible which have as large a binding energy as possible. This is a required condition for complex designs when it is difficult to tune the cooling rate.     

Expression of functional tissue factor on small vesicles of lipopolysaccharide-stimulated human vascular endothelial cells

An autopsy case of Sj?gren-Larsson syndrome (SLS), an 8-year-old boy, is presented with neuropathological investigations. Widespread deposition of 2 different types of unusual substances, stained lightly or strongly with periodic acid Schiff (PAS) was most conspicuous in this case. The first type of them, lightly stained with PAS at room temperature, was widely distributed in the central nervous system (CNS): the white matter of cerebrum and brainstem, subpial and subependymal glial layers, subpial space, perivascular space of small blood vessels, and their adjacent nervous tissue. The second type, strongly stained with PAS, small round or ellipsoid bodies, was found in the subpial, subependymal and perivascular glial layers. The first type of PAS-positive substances might be fatty alcohols or their metabolites, and the second type, some degraded products of lipids in astrocytic processes. Lipofuscin-like substances were accumulated in perivascular macrophages located around small blood vessels. Spheroid bodies (axonal swellings) were frequently observed in relay nuclei: lateral geniculate body (LGB), pontine nuclei, inferior olivary nuclei, posterior funicular nuclei, or cerebellar dentate nuclei. A lot of PAS-positive fine granules were contained in a spheroid body of LGB. Scarcity of myelinated nerve fibers was recognized in the cerebral and cerebellar white matter and the corticospinal tracts of spinal cord. Focal cortical dysgenesis, resembling that of unlayered polymicrogyria, was observed in bilateral insular cortices. Further histochemical studies are needed to explore the exact pathogenesis, but widespread deposition of PAS-positive substances in CNS may support the supposition that SLS is one of congenital errors of lipid metabolism.     

Nanofabrication of magnetic tunnel junctions by using side-edge thin film deposition

Nanostructured double ferromagnetic tunnel junctions (MTJs) are indispensable for investigation of spin-dependent single-electron transport at low temperature. A new fabrication process that enables us to reduce the size of MTJs down to nanometer scale by using the side edge of a patterned film were developed. The multilayers of MTJ partially replaced by thick Al₂O₃/Cu double layer were prepared by using electron beam lithography and lift-off, then Pt film was vacuum-evaporated onto the side edge of Al₂O₃/Cu film, which masked MTJ during following Ar ion milling. As a result, the double MTJs with the dimension of 10 nm £ 10 mm were formed beneath the Pt film. The large tunnel magnetoresistive ratio of 35% and symmetrical I–V characteristics were obtained at room temperature.     

Cytokine gene expression after allogeneic bone marrow transplantation

Cytokines produced by T lymphocytes, monocytes/macrophages, and fibroblasts play a central role in the immune response and in the development of graft-versus-host disease (GVHD). Also, it has been reported that dysregulated production of cytokines maybe the primary mediator of clinical manifestation of acute GVHD. Regarding cytokine gene expression after human allogeneic bone marrow transplantation (allo BMT), we have demonstrated increased IL-1 beta, IL-6, and TNF-alpha mRNA expression in peripheral blood mononuclear cells during the development of acute and chronic GVHD and that the degree of the increase was dependent on the severity of the disease. Furthermore, overexpression of these cytokine mRNAs could be detected before the clinical manifestations of GVHD developed. In contrast, IL-2 mRNA expression was not detected in peripheral blood mononuclear cells in GVHD patients. On the other hand, we have reported that increased mRNA expression and protein product of IL-2 and IFN-gamma were evident in the mixed lymphocyte culture of the cases who developed severe lethal transplantation-related complications. Therefore, the detection of increased IL-2 and IFN-gamma gene expression in MLC appeared to be useful for predicting transplantation-related complications in BMT patients. Furthermore, we found increased IL-2 receptor alpha subunit mRNA expression in the peripheral blood mononuclear cells during GVHD. These findings may indicate the important role of inflammatory cytokines such as IL-1 beta, IL-6 and TNF-alpha in the development of the clinical manifestation of GVHD and also may be indicative of the important role of IL-2 and the IL-2 receptor in allo response perhaps mainly as an autocrine effect.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anti‐Sway Crane Control Considering Wind Disturbance and Container Mass

A method for estimating the sway angle using an observer has already been proposed. The state observer estimates the sway angle accurately and must use the detected sway angle value. However, the estimated sway angle has an error owing to rope length error, friction force, and wind. Moreover, the container mass cannot be determined, and therefore the observer parameter is not suitable. We already proposed robust antisway control for overcoming rope length error without adding a new sensor. Further, we designed a friction disturbance observer to cancel out the influence of the friction force. In this paper, we first propose a container mass estimation method when a crane system performs rolling up control. The observer parameter can be selected using the estimated mass value. Second, in crane parallel shift control, we propose a robust antisway control even when there is a wind disturbance. We design a wind disturbance observer and propose a wind disturbance estimator to separate the friction observer output from the wind disturbance observer output. We confirm through experiments that the proposed method can reduce vibration.     

MHz-driven snubberless zero-current soft-switching high step-up DC-DC converter with a multi-resonant tank

A novel high step-up DC-DC converter suitable for the power interface of fuel cells (FC) is presented in this paper. The proposed converter features a multi-resonant tank for achieving high-step up ratio under zero current soft switching (ZCS) without any snubber circuits. The simple and minimized-component topology is beneficial for megahertz driving of gallium nitride (GaN) power transistors with effective reductions of switching loss, electromagnetic emission interference (EMI) noise, and ripple-free DC input current. Mode-transitional power stages are described in detail, following that the high step-up principle is revealed by means of frequency-domain analysis. The essential performances of the proposed circuit topology are demonstrated by simulation and experiment of 1.8 MHz-120W prototype whereby effectiveness of the snubberless and multi-resonant topology are verified from the practical point of view.