In this work, a novel and simple bone morphogenetic protein (BMP)-2 carrier is developed, which enables localized and controlled release of BMP-2 and facilitates bone regeneration. BMP-2 is localized in the gelatin methacrylate (GelMA) micropatterns on hydrophilic semi-permeable membrane (SNM), and its controlled release is regulated by the concentration of GelMA hydrogel and BMP-2. The controlled release of BMP-2 is verified using computational analysis and quantified using fluorescein isothiocyanate-bovine serum albumin (FITC-BSA) diffusion model. The osteogenic differentiation of osteosarcoma MG-63 cells is manipulated by localized and controlled BMP-2 release. The calcium deposits are significantly higher and the actin skeletal networks are denser in MG-63 cells cultured in the BMP-2immobilized GelMA micropattern than in the absence of BMP-2. The proposed BMP-2 carrier is expected to not only act as a barrier membrane that can prevent invasion of connective tissue during bone regeneration, but also as a carrier capable of localizing and controlling the release of BMP-2 due to GelMA micropatterning on SNM. This approach can be extensively applied to tissue engineering, including the localization and encapsulation of cells or drugs.

STATEMENT OF PROBLEMUse of custom tray and tray adhesive is clinically recommended for elastomeric impression material. However there is not clear mention of drying time of tray adhesive in achieving appropriate bonding strength of tray material and impression material.PURPOSEThis study is to investigate an appropriate drying time of tray adhesives by evaluating tensile bonding strength between two types of polyvinylsiloxane impression materials and resin tray, according to various drying time intervals of tray adhesives, and with different manufacturing company combination of impression material and tray adhesive.MATERIAL AND METHODSAdhesives used in this study were Silfix (Dentsply Caulk, Milford, Del, USA) and VPS Tray Adhesive (3M ESPE, Seefeld, Germany) and impression materials were Aquasil Ultra (monophase regular set, Dentsply Caulk, Milford, Del, USA) and Imprint II Garant (regular body, 3M ESPE, Seefeld, Germany). They were used combinations from the same manufacture and exchanged combinations of the two. The drying time was designed to air dry, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. Total 240 of test specimens were prepared by auto-polymerizing tray material (Instant Tray Mix, Lang, Wheeling, Il, USA) with 10 specimens in each group. The specimens were placed in the Universal Testing machine (Instron, model 3366, Instron Corp, University avenue, Nowood, MA, USA) to perform the tensile test (cross head speed 5 mm/min). The statistically efficient drying time was evaluated through ANOVA and Scheffe test. All the tests were performed at 95% confidence level.RESULTSThe results revealed that at least 10 minutes is needed for Silfix-Aquasil, and 15 minutes for VPS Tray Adhesive-Imprint II, to attain an appropriate tensile bonding strength. VPS Tray Adhesive-Imprint II had a superior tensile bonding strength when compared to Silfix-Aquasil over 15 minutes. Silfix-Aquasil had a superior bonding strength to VPS Tray Adhesive-Aquasil, and VPS Tray Adhesive-Imprint II had a superior tensile bonding strength to Silfix-Imprint II at all drying periods.CONCLUSIONSignificant increase in tensile bonding strength with Silfix-Aquasil and VPS Tray adhesive-Imprint II combination until 10 and 15 minutes respectively. Tray adhesive-impression material combination from the same company presented higher tensile bonding strength at all drying time intervals than when using tray adhesive-impression material of different manufactures.

Nobody doubts that the high area density recording and miniaturization of the devices in the data storage are in the general trend. What matters now is how to compact the data in a small area and how to decrease the device size. For the last decade, a lot of researchers engaged in the optical memory have expected the near®eld recording (NFR) technology to be able to bring the remarkable results. However, they have been confronted with many obstacles including heat, contamination, dynamics of optical head in the unsealed environment, etc. In this paper, we propose the new concept of a solid immersion lens (SIL) with a potential to be able to resolve the critical issues on the way to the commercialization of the high areal density optical recording using the near®eld recording technology. IntroductionThere are two ways to increase the recording density of the optical data storage. The ®rst method is to reduce the wavelength k in proportion to the spot size of the beam, and the second way is to increase the numerical aperture (NA) in inverse proportion to the spot size. The use of the shorter wavelength (green or blue light sources) can be considered as a relatively simple method. The present optical disc drive (ODD) technology based on far-®eld recording in which the focused beam size is limited by diffraction can not generate the small spot enough to satisfy the next generation optical storage with ultra high areal density. Motivated by the achievement of the advanced optical data storage device for the high density, the research groups and industries have considered the near-®eld recording (NFR) technique as a key method because the near-®eld recording can circumvent the far-®eld diffraction limit. In the early 1990s, Mans®eld and Kino developed a new microscope by replacing a liquid immersion lens with a solid immersion lens (Mans®eld and Kino, 1990). A few years later, they proposed the application of the SIL to the optical storage system to improve the transverse resolution of a conventional pickup head by placing a perfect hemisphere glass lens, namely SIL, between the objective and the disc (Mans®eld et al., 1993). In this system, the collimated beam passes through the objective lens which lets the beam pass perpendicularly into the surface of the SIL without refraction (see Fig. 1). To achieve even higher areal density, the study of a super-hemispherical SIL with a higher NA than a hemispherical one was presented by Ichimura from SONY, Hayashi and Kino from Stanford University (Ichimura et al., 1997). In the super-hemispherical SIL system the beam from the objective lens converges at a point distant (r/n) from the center of the SIL and the NA eff of the objective is increased by the refractive index of itself squared. However, the NA eff of the object is limited by the fact that rays below the plane tangential to the curvature cannot enter the SIL (see Fig. 2). The recent paper reported the heat and contamination issues of the conventional solid immersion lens in the shape of a sphere. The heat from the su...