Cutting process for aluminum foam fabricated by sintering and dissolution process

In this study, a cutting process using a milling machine for Al foam with and without remaining NaCl fabricated by a sintering and dissolution process was proposed. By comparing the surface pore structures of the Al foam after the cutting process, the possibility of cutting Al foam using a milling machine while retaining its pore structures was investigated. Although some flashes were observed around the pores, most of the pores remained at the cutting surface and retained their shape. Therefore, it was found that Al foam can be cut using a milling machine without fracturing its pore structures at the surface by retaining the NaCl spacers. Namely, NaCl, which was used as spacers to generate pores in Al, can also have the role of strengthening Al foam during the cutting process.     

High‐Performance Long‐Term‐Stable Dopant‐Free Perovskite Solar Cells and Additive‐Free Organic Solar Cells by Employing Newly Designed Multirole π‐Conjugated Polymers

Perovskite solar cells (PSCs) and organic solar cells (OSCs) are promising renewable light‐harvesting technologies with high performance, but the utilization of hazardous dopants and high boiling additives is harmful to all forms of life and the environment. Herein, new multirole π‐conjugated polymers (P1–P3) are developed via a rational design approach through theoretical hindsight, further successfully subjecting them into dopant‐free PSCs as hole‐transporting materials and additive‐free OSCs as photoactive donors, respectively. Especially, P3‐based PSCs and OSCs not only show high power conversion efficiencies of 17.28% and 8.26%, but also display an excellent ambient stability up to 30 d (for PSCs only), owing to their inherent superior optoelectronic properties in their pristine form. Overall, the rational approach promises to support the development of environmentally and economically sustainable PSCs and OSCs.     

Surface modification of titanium by hydrothermal treatment in Mg-containing solution and early osteoblast responses

Surface modification on titanium was carried out in order to improve its bioactivity. Pure titanium was hydrothermally treated in distilled water and 0.1 M MgCl₂ solutions at 200°C for 24 h. Surface morphology, roughness, wettability and chemical composition were characterized before and after treatment. Bovine serum albumin was used as model to study protein adsorption. MC3T3-E1 cells were cultured and initial cell attachment, morphology, proliferation were evaluated. After hydrothermal treatment, nano-sized precipitations were observed and samples showed superhydrophilicity. Magnesium (Mg) was immobilized into titanium surface by hydrothermal treatment. Protein adsorption was significantly increased on Mg-containing samples. Cell attachment was improved and cell spreading was enhanced on Mg-containing samples compared with untreated or those treated in distilled water. Increased early cellular attachment on the MgTi surface resulted in subsequent increase of number of proliferated cells. Hydrothermal treatment in MgCl₂ solution was expected to be an effective method to fabricate titanium implant with good bioactivity.     

Cross-sectional monitoring of resin impregnation using an area-sensor array in an RTM process

It is difficult to visualize the flow in the cross-section direction, and most conventional methods for monitoring resin flow are limited to the in-plane direction. This study investigates the monitoring of the cross-section of resin impregnation using an area-sensor array during a resin transfer molding (RTM) process. The area-sensor array is mounted on a thin polyimide film that is integrated with the inter-digital electrode array and associated wiring, and forms the bottom layer of the stacked composite laminates. Each area-sensor is square-shaped and measures the capacitance and electrical resistance of the sensor region. First, we constructed the equivalent electrical circuit model of in-plane and out-of-plane impregnation. Using this model, we proposed a method to identify the flow direction and the ratio of the impregnation thickness by measuring the electrical capacitance and resistance. The validity of the model was confirmed by comparison with the experimental results. To demonstrate the applicability of the proposed method, the area-sensor array was applied to monitoring the resin injection through-thickness to the glass fabric laminates. As a result, the cross-section of the impregnated area could be estimated and the estimated area provided a good match to the actual impregnated area.     

Laminar and blazed type holographic gratings for a versatile soft x-ray spectrograph attached to an electron microscope and their evaluation in the 50-200 eV range

Laminar and blazed type holographic varied-line-spacing spherical gratings for use in a versatile soft x-ray flat-field spectrograph attached to an electron microscope are designed, fabricated, and evaluated. The absolute diffraction efficiencies of laminar (or blazed) master and replica gratings at 86.00° incidence evaluated by synchrotron radiation show over 5% (or 8%) in the 50-200 eV range with the maxima of 22% (or 26%-27%). Also the resolving power evaluated by a laser produced plasma source is in excess of 700 at the energy near the K emission spectrum of lithium (~55 eV) for all gratings. Moreover, the K emission spectrum of metallic Li with high spectral resolution is successfully observed with the spectrograph attached to a transmission electron microscope.     

Electrochemical Characterization of a Porous Pt Nanoparticle ＂Nanocube-Mosaic＂ Prepared by a Modified Polyol Method with HCI Addition

Porous and single crystalline platinum (Pt) nanoparticles (NPs) have been successfully synthesized by reduction of H₂PtCl₆·6H₂O and then investigated by optical spectroscopy and transmission electron microscopy. H₂PtCl₆·6H₂O was reduced using ethylene glycol in the presence of polyvinylpyrrolidone under highly acidic conditions (pH < 1) to form single crystalline Pt particles about 5 nm in size. These particles were then stacked via {100} facets, forming 50-nm length porous nanocubes with a mosaic structure. The porous Pt NPs exhibited excellent catalytic properties for methanol oxidation. In particular, the electrochemical surface area was ∼63 m²/g, five times higher than that for non-porous Pt NPs prepared using a conventional method. We suggest that the high catalytic activity of porous Pt NPs is due to a combination of the crystalline structure having exposed {100} facets and a porous morphology.      

Low-loss high-silica single-mode channel waveguides

Low-loss high-silica single-mode channel optical waveguides of 0.1 dB/cm have been fabricated on crystal silicon substrates with fibre coupling losses of less than 0.05 dB by flame hydrolysis deposition and reactive ion etching. Directional couplers have also been fabricated with excess loss of 0.5 dB by this waveguide fabrication technique.     

Analytic Self-Consistent Condensates in Quasi-1D Superfluid Fermi Gases in the Andreev Approximation

We present an analytic method to approach Eilenberger equation and the associated Bogoliubov–de Gennes equation for quasi-1D fermionic gases. The problem of finding self-consistent inhomogeneous condensates is reduced to solving a certain class of nonlinear Schrödinger equations, whose most general solitonic solution is indeed available. Previously known solutions can be retrieved by taking appropriate limits in the parameters. The applicability of the method extends to systems with population imbalance and subject to external potential. In particular we show that fermionic zero-modes are robust against population imbalance.