By fixing charged colloidal crystals in a poly(acrylamide) hydrogel matrix, we fabricated photonic crystals whose diffraction peak wavelengths were tunable by applying mechanical stress. The reflection spectrum for a single crystal grain was measured by applying microspectroscopy under compression. The photonic band gap wavelength shifted linearly and reversibly over almost the entire visible light wavelength region (460-810 nm).
In the in vitro evaluation of Sun Protection Factor (SPF), the photostability of the ultraviolet (UV) filters can have a major impact, especially for high-SPF formulations, but is generally not taken into consideration. In this study, we present a UV transmission spectrum measurement system utilizing a high-sensitivity UV photomultiplier tube with concomitant evaluation of photostability. We have developed an algorithm to estimate SPF in vitro by converting the amount of UV light transmission through the sunscreen layer into cumulative relative erythema effectiveness to obtain one minimal erythema dose. Thus, the algorithm uses the same endpoint as in vivo SPF methods, but with a photomultiplier tube as the detector instead of skin. The values obtained showed an excellent correlation with in vivo SPF values, even for high-SPF sunscreens exceeding SPF 50. This method should be suitable as an in vitro SPF testing method for regulatory purposes.
Integrated four-channel all-fiber upconversion single-photon-detector with adjustable efficiency and dark count Abstract. Quantum cryptography can provide unconditional secure communication between two authorized parties based on the basic principles of quantum mechanics. However, imperfect practical conditions limit its transmission distance and communication speed. Here, we implemented the differential phase shift (DPS) quantum key distribution (QKD) with an up-conversion-assisted hybrid photon detector (HPD) and achieved a 1.3 Mbits per second secure key rate over a 10 km fiber, which is tolerant against photon number splitting (PNS) attack, general collective attacks on individual photons and any other known sequential unambiguous state discrimination (USD) attacks.
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