An AlGaN ultraviolet-B laser diode at 298 nm was realized at room temperature using pulse operation. The laser diode has a lattice-relaxed Al0.6Ga0.4N layer from the underlying AlN/sapphire template and a composition-graded p-AlGaN cladding layer. The multimodal laser spectrum with proper polarization properties at 298 nm was obtained over the threshold current at 0.90 A corresponding to 67 kA cm–2. By broadening the width of the p-electrode to 11.5 μm, the threshold current density decreased to 41 kA cm–2.
Summary. Background: An increased level of obesity-induced plasma plasminogen activator inhibitor-1 (PAI-1) is considered a risk factor for cardiovascular disease. Aim: The present study investigates whether the circadian clock component CLOCK is involved in obesity-induced PAI-1 elevation. Methods: We examined plasma PAI-1 and mRNA expression levels in tissues from leptin-deficient obese and diabetic ob/ob mice lacking functional CLOCK protein. Results: Our results demonstrated that plasma PAI-1 levels were augmented in a circadian manner in accordance with the mRNA expression levels in ob/ob mice. Surprisingly, a Clock mutation normalized the plasma PAI-1 concentrations in accordance with the mRNA levels in the heart, lung and liver of ob/ob mice, but significantly increased PAI-1 mRNA levels in adipose tissue by inducing adipocyte hypertrophy in ob/ob mice. The Clock mutation also normalized tissue PAI-1 antigen levels in the liver but not in the adipose tissue of ob/ob mice. Conclusion: These observations suggest that CLOCK is involved in obesity-induced disordered fibrinolysis by regulating PAI-1 gene expression in a tissue-dependent manner. Furthermore, it appears that obesity-induced PAI-1 production in adipose tissue is not closely related to systemic PAI-1 increases in vivo.
In nonpolar polymers, positronium (Ps) is dominantly formed by fast intraspur reactions of the energetic positron, but its formation is partially contributed by recombination of weakly bound Mott-Wannier-like positron-electron pairs and is susceptible to electric field and positron irradiation induced perturbations. The average initial energy of para-Ps (p-Ps) formed by recombination is found to be about half the energy of ordinary p-Ps dominantly formed by the fast intraspur reactions.
Aluminum gallium nitride (AlGaN)-based ultraviolet-B band laser diodes (LDs) with a p-type AlGaN cladding layer using polarization doping were fabricated on lattice-relaxed Al0.6Ga0.4N/AlN/sapphire. The threshold current density Jth and lasing wavelength of this LD were 25 kA cm−2 and 298 nm, respectively. The internal loss (αi) was estimated by means of a variable stripe length method using optical excitation. The αi value of this LD was relatively low (i.e. <10 cm−1), thus suggesting that the device is characterized by both, proper light confinement and low internal loss.
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