dispersion by semiconductor devices based on the electron energy bandgap-the forbidden energies separating allowed energy bands. An example of photonic crystals with simple periodic arrays formed from dielectric spheres is shown in Figure 1. According to Bragg's equation, [3] the wavelength of the photons scattered from the crystal lattice can be calculated by the following formula (Equation (1)where d is the diameter of the sphere, m is the Bragg reflection order, and θ is the angle between the normal and incident light. The value of n a is defined as the weighted sum of sphere portion refractive indices and the gap portion (Equation (2)) [3] ∑ φ = n n i i a 2 2(2)where n is the refractive index of different components inside photonic crystals and φ i is the volume fraction of each i portion. For the close-packed structure, φ i of the sphere portion is 0.74. Photon propagation can be precisely controlled by designing a photonic crystal with a specific photonic bandgap. Hence, a future trend in the design of photonic crystals may lie in the modification and realization of spontaneous emission by light emitters integrated with these crystals. [4][5][6] Spontaneous emission refers to an optical process in which a quantum mechanical system in an excited state returns to a lower-energy or ground state and releases energy in the form of a photon. The quantum system could be an atom, molecule or nanocrystal. The photoluminescence (PL) produced by spontaneous emission plays a crucial role in conventional modern technologies used in daily lives, such as television screens (cathode ray tubes), plasma display panels, and fluorescence tubes.While spontaneous emission has enabled the progress of several technologies, uncontrolled spontaneous emission can limit the performance of photonic devices in many applications. One such limitation in device performance in light-emitting diodes (LEDs) occurs when an excessive number of photons generated from spontaneous emission are confined or trapped within the device. This shortcoming is also observed in laser operation when photon emission fails to couple with lasing processes, resulting in energy loss and noise in the signal output. Consequently, precise control over the propagation of spontaneous emission is critical. Due to their ability to manipulate light The modulation of luminescence is essential because unwanted spontaneousemission modes have a negative effect on the performance of luminescencebased photonic devices. Photonic crystals are promising materials for the control of light emission because of the variation in the local density of optical modes within them. They have been widely investigated for the manipulation of the emission intensity and lifetime of light emitters. Several groups have achieved greatly enhanced emission by depositing emitters on the surface of photonic crystals. Herein, the different modulating effects of photonic crystal dimensions, light-emitter positions, photonic crystal structure type, and the refractive index of photonic crystal building bl...

Sleep deprivation negatively influences all aspects of health. Oxidative stress and inflammatory responses induced by sleep deprivation participate in its adverse effects but the regulatory mechanisms to counteract them remain poorly understood. In mice subjected to sleep deprivation for 7 days, we found activation of microglia and astrocyte accompanied by down-regulation of α7 nicotinic acetylcholine receptor (α7-nAChR) and reduced activation of downstream PI3K/AKT/GSK-3β. These changes occurred with an increase of pro-inflammatory factors, together with reduced levels of anti-inflammatory factors, transcriptor Nrf-2, and anti-oxidant enzyme HO-1. Administration of an α7-nAChR agonist PHA-543613 induced activation of PI3K/AKT/GSK-3β, and reversed changes in pro-inflammatory and anti-inflammatory factors, Nrf-2 and HO-1. These results suggest that stimulation of α7-nAChR reduce neuroinflammation and oxidative stress after chronic sleep deprivation.

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Photonic crystals (PCs) have long been considered effective for tuning upconversion luminescence due to their photonic band gap (PBG) and the redistribution of density of optical states (DOS). Although the emission intensity can be changed obviously by the PC effect, rarely an obvious lifetime change consistent with theory is observed due to the low refractive index of PS or SiO spheres in the commonly used PCs. Herein, CdS/NaYF:Yb,Er composite PCs with a high refractive index contrast are fabricated in one step with upconversion nanoparticles filled inside CdS PCs. When the upconversion emission peak lies at the edge of the PBGs of the composite PCs, a dramatic decrease in lifetime by 28% and 41% is observed for the green and red emissions, respectively. At the same time, obvious emission intensity enhancements are also observed. In contrast, PS PCs with a low refractive index contrast show a slight effect on the lifetime of upconversion luminescence with their emission peak at the edge of the PBGs. Our results agree well with theory and prove that a sufficiently large refractive index contrast is necessary for PCs to dramatically tune the luminescence lifetime and intensity simultaneously.