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An elastic layer fabricated by photo-crosslinked polyurethane (PU) is introduced for the first time for dental composite restoration. The introduction of this layer can effectively inhibit water permeation through the dental adhesive layer to the resin composites for its perfect hydrophobic property and its excellent elastic property. The results show that only minimum microleakage was observed in the experimental group (composite restoration with elastic layer), while significant microleakage was observed in the control group. This new concept based on this elastic layer is first presented for the first time in the composite restoration field. This study may shift the future research focus from increasing the mechanical properties of dental resin composites to an alternative solution for limited restoration lifetime based on the use of an elastic layer intermediate between the composite adhesive and the dental tissue.

A new and effective organic-inorganic hybrid hydrophilic anti-fog coating was proposed and prepared. As is well-known, the presence of an inorganic component typically decreases the hydrophilicity and transparency of the coating. To solve this problem, we used polyethylene glycol with two different molecular weights to modify the si-lane coupling agent and mixed it with hydrophilic copolymer to form coating formulas. We coated these formulas on polycarbonate(PC) substrates to measure the anti-fogging properties via contact angle and anti-fogging tests, com-pared their transparency properties using UV-Vis spectra and evaluated the hardness using a pencil hardness tester. The results demonstrate that the molecular weight of PEG has a strong influence on the properties of the anti-fog coatings. After the corresponding optimization, we manufactured an excellent anti-fog coating. In addition to good adhesion and hardness, the coating also exhibited excellent mechanical properties, optical transparency and perfect anti-fogging performance.

Some important parameters are optimized for a 9?9 polymer arrayed waveguide grating multiplexer around the central wavelength of 1.55??m with the wavelength spacing of 1.6?nm. These parameters include the thickness and width of the guide core, diffraction order, pitch of adjacent waveguides, path length difference of adjacent arrayed waveguides, focal length of slab waveguides, free spectral range, the number of input/output channels and the number of arrayed waveguides. Finally, a schematic waveguide layout of this device is presented, which contains 2 slabs, 9 input and 9 output channels, and 91 arrayed waveguides.

There is considerable interest in the effect of high energy radiation on triblock copolymer, SBS. Basheer and Dole have done some works about that(Basheer and Dole, 1982). In this paper, we study the effects of radiation crosslinking on the structure and mechanical properties of SBS, about which there have been no reports up to now. The following scientific problems are discussed: The variation of glass transition temperatures with dose; The effects of the ratio of B/S on the gel content; Mechanical properties of the irradiated samples.