Previously, we found that osteogenic responses to zirconia co-doped with niobium oxide (Nb ) are comparable with responses to titanium, which is widely used as a dental implant material. The present study aimed to evaluate the in vitro osteogenic potential of hydroxyapatite (HA)-coated zirconia by an aerosol deposition method for improved osseointegration. Surface analysis by scanning electron microscopy and x-ray diffraction proved that a thin as-deposited HA film on zirconia showed a shallow, regular, crater-like surface. Deposition of dense and uniform HA films was measured by SEM, and the contact angle test demonstrated improved wettability of the HA-coated surface. Confocal laser scanning microscopy indicated that MC3T3-E1 pre-osteoblast attachment did not differ notably between the titanium and zirconia surfaces; however, cells on the HA-coated zirconia exhibited a lower proliferation than those on the uncoated zirconia late in the culture. Nevertheless, ALP, alizarin red S staining, and bone marker gene expression analysis indicated good osteogenic responses on HA-coated zirconia. Our results suggest that HA-coating by aerosol deposition improves the quality of surface modification and is favorable to osteogenesis.

Magneto-/electro-chromatic reflective color tunability is confirmed using hydrophobic surface modified magnetite nanoparticles. The optical reflective color spectra and color gamut demonstrate the promising applications in reflective displays.

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A Fabry-Pérot cavity (FPC) array antenna providing both very high gain and circularly-polarised (CP) behaviour is proposed. To increase antenna gain and to obtain the CP characteristic, a superstrate is introduced above 2 × 2 feeding microstrip patch antennas (MPAs), which converts linearly-polarised (LP) incident waves to CP waves. Input phase difference between MPAs is designed to be exactly 90°to generate the high-quality CP characteristic in cooperation with the superstrate. By using the FPC, very high gain can be obtained with only a small number of feeders, which also provides another advantage of low mutual coupling among the neighbouring MPAs. Although the proposed antenna is very simple in its structure, it readily provides very high gain, high-quality CP property and very low axial ratio in a wide frequency range, which are great advantages compared with conventional CP antennas.Introduction: Various approaches have been proposed to improve the antenna gain and axial ratio (AR) of circularly-polarised (CP) antennas fed by single or multiple microstrip patch antennas (MPAs) [1][2][3][4][5]. A technique providing sequentially rotating phase values into each MPA has also been used to improve AR bandwidth, polarisation purity and symmetry in radiation patterns [2][3][4][5]. However, the conventional sequential rotation technique requires an array construction consisting of a large number of patch antennas, which increases not only the complexity in antenna design, but feed loss causing degradation of overall antenna efficiency.In this Letter, we present a high gain Fabry-Pérot cavity (FPC) antenna for a wireless local area network (WLAN) (5.15-5.35 GHz) application, which can radiate CP waves with a fairly low AR property. Compared with conventional CP array antennas, our antenna has some advantages such as high gain, simple feeding networks and excellent CP quality. By using an FPC technique, we can obtain very high gain with the help of only 2 × 2 arrays of simple linearly-polarised (LP) rectangular MPAs. Owing to a large separation distance among neighbouring antennas, the mutual coupling effect is much less than that in the conventional arrays. To verify our design approach, our theoretical prediction is compared with simulations using CST Microwave Studio. Good agreement between the predicted and measured data shows the validity and usefulness of our approach.

A suitable classification of variable stars is an important task for understanding galaxy structure and evaluating stellar evolution. Most traditional approaches for classification have used various features of variable stars such as period, amplitude, color index, and Fourier coefficients. Recently, by focusing only on the light curve shape, Deb and Singh proposed a classification method based on multivariate principal component analysis (PCA). They applied the PCA method to light curves and compared its results with those obtained by Fourier coefficients. In this article, we propose a new procedure based on the thick-pen transform for obtaining accurate information on the light curve shape as well as for improving the accuracy of classification. The proposed method is applied to the data sets of variable stars from the Stellar Astrophysics and Research on Exoplanets (STARE) project and a small number of stars from Massive Compact Halo Objects (MACHO).

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We propose new and practical design methods of a low-profile and high-gain leaky wave antenna (LWA). Based on a required dispersion relationship, we suggest appropriate equivalent transmission line models representing a unit cell of the LWA, which determines a specific frequency of maximum radiation together with optimal circuit values essential for maximum gain at a boresight direction. According to the equivalent model approach, we can design overall structure of the high-gain LWA very easily and accurately. In addition, we also propose a novel way of deriving dual-band resonance from a simple single-band-resonating LWA by means of an electromagnetic band gap (EBG) structure. In order to make the LWA resonate at two different frequencies, we intentionally introduce a propagation stop band into an existing one pass band by inserting an EBG structure. By doing so, we can obtain two new specific conditions resulting in maximum radiation toward a boresight direction at the two resonant frequencies locating on both sides of the inserted stop band. All experimental results show good agreement with theoretical predictions, which proves the validity and effectiveness of our approaches.

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