Multilayer formation via spinodal decomposition in TiO2-VO2 epitaxial films on sapphire substrates

We present multilayer formation via spinodal decomposition in rutile TiO₂-VO₂ (TVO) epitaxial films on sapphire substrates. (001)- and (101)-oriented TVO solid-solution films are grown epitaxially on TiO₂/Al₂O₃ using a pulsed laser deposition technique and annealed inside the spinodal region. X-ray diffraction measurements and scanning transmission electron microscopy (STEM) observations show that the films are phase-separated along the [001] direction and lamellar structures are formed in a parallel or slanted direction to the sapphire substrates depending on the film orientation. The results indicate the multilayer formation via spinodal decomposition in the TVO films. STEM investigations also reveal a relatively high Ti concentration in the decomposed phases, reflecting the influence of lattice deformation on the phase decomposition in the films. Our work shows that spinodal decomposition is a promising approach for the formation of a multilayer structure in TVO films and helps deepen understanding the spinodal decomposition in TVO system.     

Experimental and simulation studies on intermittent aeration in an oxidation ditch

The simultaneous removal of nitrogen and organic substances can be enhanced by establishing an anoxic stage through intermittent aeration in the oxidation ditch system. In this study, investigations on substrate removal and the optimal operating conditions of a laboratory-scale oxidation ditch system with intermittent aeration were carried out using synthetic wastewater. Up to 96% of the carbonaceous substances and 93% of total nitrogen were removed. A theoretical model developed for this system gave good agreement with the experimental data.     

Precision control of radical polymerization via transition metal catalysis: from dormant species to designed catalysts for precision functional polymers

In the past decade, living radical polymerization has provided one of the most versatile methods to precisely construct designed polymer architectures with complexity and polar functionality. This process takes advantage of carbon-radical intermediates, which tolerate a variety of functional groups in monomers and reaction media. "Transition metal-catalyzed living radical polymerization", one of these living systems, has widely been employed for precision polymer synthesis. Not only can this process produce well-defined functional polymers, but it can also generate hybrids or conjugates with other (often biological) materials. Metal-catalyzed systems retain the advantages of conventional radical polymerization but distinguish themselves through a catalytic reversible halogen exchange equilibrium: the growing radical exists alongside a dormant speciesa covalent precursor capped with a terminal halogen from an initiator. The catalyst dictates the selectivity, exchange rate, and control over the polymerization. This Account provides an updated overview of our group's efforts in transition metal-catalyzed living radical polymerization with specific emphasis on the design of metal catalysts and the resulting precision polymer syntheses. With increasing use of the living processes as convenient tools for materials synthesis, researchers are currently seeking more active and versatile metal catalysts that are tolerant to functional groups. Such catalysts would enable a wider range of applications and target products, would have low metal content, could be readily removed from products, and would allow recycling. Since we first developed the "transition metal-catalyzed living radical polymerization" with RuCl 2(PPh 3) 3, FeCl 2(PPh 3) 2, and NiBr 2(PPh 3) 2, we have strived to systematically design metal catalysts to meet these new demands. For example, we have enhanced catalytic activity and control through several modifications: electron-donating or resonance-enhancing groups, moderate bulkiness, heterochelation via a ligand, and halogen-donor additives. For some catalysts, the use of amphiphilic and polymeric ligands allow efficient recovery of catalysts and convenient use in aqueous media. We have also used ligand design (phosphines) and other methods to improve the thermal stability of iron- and nickel-based catalysts and their tolerance to functional groups.     

Space change behavior in full scale ±250 kV dc XLPE cables

Space charge in full size ±250 kV dc cables was measured using a pulse-electroacoustic method. Two newly developed types of dc XLPE cables with 20 mm thick insulation were subjected to measurements at a dc voltage of 500 kV, keeping the conductor temperature either at room temperature or at 85°C. Qualitative analyses of the space charge distribution and the quantitative analysis of the electric fields in the vicinity of semicon interfaces were made. It was shown that the field in the vicinity of the inner semiconductor tends to increase by 10 to 40% when the polarity of the applied voltage was switched, in the case when the conductor was kept at 85°C. However, the distortion of the electric field was significantly smaller than that expected with conventional XLPE cables. As a result, dc cables are considered to have stable dc characteristics from the viewpoint of space charge behavior. © 1998 Scripta Technica, Electr Eng Jpn, 124(2): 16–28, 1998     

Evaluation of poly(3-hexylthiophene)/polymeric insulator interface by charge modulation spectroscopy technique

We have investigated the sub-band gap states behaviors in P3HT MIS diodes and P3HT Schottky diode by the combination of C–V characteristics and the charge modulation spectroscopy (CMS) measurements. Single-layered heat-treated P3HT film sandwiched by ITO and Al electrodes behaves as a dielectric film, whereas it behaves as Schottky diode when oxygen molecules were doped. The thickness of depletion layer at Al/P3HT interface is controlled by external voltage, and there are two peaks at around 1.3 eV and 1.95 eV in CMS curves. On the other hand, P3HT MIS diodes deposited on polymeric gate insulators have three peaks in CMS curves at around 1.3, 1.6 and 1.95 eV respectively in accumulation. The first peak observed was attributed to the optical transition of polarons in isolated (1D) P3HT chain, and it was related to the field effect mobility and conjugation length in lamellae chains. The second peak observed was attributed to the optical transition of delocalized polarons in π-stacked (2D) P3HT chains, and the peak intensity became strong for highly crystallized P3HT film. The third peak was attributed to the deeply trapped charges in amorphous P3HT region, respectively.     

Hierarchical structures hydrogel evaporator and superhydrophilic water collect device for efficient solar steam evaporation

Efficient light absorption and trapping are of vital importance for the solar water evaporation by hydrogel-based photothermal conversion materials.Conventional strategies are focused on the development of the composition and structure of the hydrogers internal network.In our point of view,the importance of the surface structure of hydrogel has usually been underestimated or ignored.Here inspired by the excellent absorbance and water transportation ability of biological surface structure,the hierarchical structured hydrogel evaporators(HSEs)increased the light absorption,trapping,water transportation and water-air interface,which is the beneficial photothermal conversion and water evaporation.The HSEs showed a rapid evaporation rate of 1.77 kg·m^-2·h^-1at about 92%energy efficiency under one sun(1 kW·m^-2).Furthermore,the superhydrophilic window device was used in this work to collect the condensed water,which avoids the light-blocking caused by the water mist formed by the small droplets and the problem of the droplets stick on the device dropping back to the bulk water.Integrated with the excellent photothermal conversion hydrogel and superhydrophilic window equipment,this work provides efficient evaporation and desalination of hydrogel-based solar evaporators in practical large-scale applications.     

Determination of humic substances in deep groundwater from sedimentary formations by the carbon concentration-based DAX-8 resin isolation technique

ABSTRACT

Concentrations of humic substance (HS) in deep groundwater from sedimentary formations were determined by the carbon concentration-based DAX-8 resin isolation technique. The groundwater samples were collected from test galleries at depths of 140, 250 and 350 m at the Horonobe Underground Research Laboratory (URL) in Hokkaido, and two observation wells with different depths of 560 and 1050 m in Niigata, Japan. The analytical condition was optimized for the groundwater samples with a high salinity and a high concentration of dissolved organic matters (DOMs). The analytical results showed that the HS concentrations varied from 7.8 to 23.5 mg-C dm^?3, depending on the depth and the area. The HS proportions to DOM (%HS) were evaluated to be 58 – 67% and slightly decreased in the deeper groundwater. The regression analysis showed that the HS concentrations are positively correlated with the DOM concentrations. In addition, the low deviation of the %HS values from the slope in the regression equation indicated that the slight variation of %HS can be trivial in the prediction of the concentration of HS. In previous studies, HS concentrations in the groundwater had been determined with a large uncertainty and potential usage of the regression equation for the prediction had not been elucidated. Therefore, the results in this study can provide useful information on the HS concentration and its prediction from the DOM concentration in deep groundwater from sedimentary formations.     

Development of a new method for joint damping identification in a bolted lap joint

Mechanical joints have considerable effects on dynamic behaviour of machine tools; thus, joint damping identification is important in studying the dynamics of mechanical structures. Due to the difficulties in analysis of microslip friction, the experimental prediction of microslip joint dynamics is of great importance. In this study, a new experimental approach is proposed to determine the damping of bolted lap joints. Because of the complex nature of the mechanical joints, the lap joint is isolated through the addition of a mechanical resonator, which consists of a lumped mass and spring, to the bolted structure. The frequency response function (FRF) of this system is used for joint damping identification. This approach is used for bolted structures under both translational and torsional excitations and overcomes difficulties associated with slip boundaries identification in the joint interface. The method is verified by comparing the obtained results with those of the hysteresis loop approach.     

Amino acid sequence requirement for efficient incorporation of glycosylphosphatidylinositol-associated proteins into the cell wall of Saccharomyces cerevisiae

During cell wall biogenesis in Saccharomyces cerevisiae, some glycosylphosphatidylinositol (GPI)-attached proteins are detached from GPI moieties and bound to beta-1,6-glucan of the cell wall. The amino acid sequence requirement for the incorporation of GPI-attached proteins into the cell wall was studied by using reporter fusion proteins. Only the short omega-minus region composed of five amino acids, which is located upstream of the omega site for GPI attachment, determined the cellular localization of the GPI-associated proteins. Within the omega-minus region, amino acid residues at the omega-4 or -5 and omega-2 sites were important for the cell wall incorporation. Yap3p, a well characterized GPI-anchored plasma membrane aspartic protease, was localized in the cell wall when the omega-minus region was mutated to sequences containing Val or Ile at the omega-4 or -5 site and Val or Tyr at the omega-2 site.     

Clinical analysis of small-sized peripheral lung cancer

OBJECTIVE: In Japan, with the initiation of the lung cancer screening program, small-sized peripheral lung cancer in which the diameter is 2 cm or less has been increasing. The purpose of this study is to determine the clinicopathologic behavior of small-sized lung cancer. METHODS: Four hundred ninety-six patients with cT1 N0, peripheral, resected non-small-cell lung cancer, who were operated on between 1980 and 1996, were selected, grouped by tumor diameter or histologic type, and then analyzed for clinicopathologic behavior. On the basis of measured diameter roentgenographically, the patients were divided into two groups; group c-S with lesions 2 cm or less in diameter and group c-L with lesions 2.1 to 3 cm in diameter. RESULTS: Lymph node metastasis was recognized in 18% of group c-S, in 23% of group c-L, and in 21% for the entire clinical group. The rate of those with the progressive state was 19% in group c-S and 26% in group c-L. The 5-year survival was 79.5% in group c-S and 69.3% in group c-L (i.e., there was a significant difference between the two groups). CONCLUSION: Compared with the patients with lesions 2.1 to 3 cm in diameter, the patients with small-sized lung cancer had a milder progressive state and a better prognosis.