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The high acceptor ionization energy and, thus, low carrier concentration in p-type III-nitride have widely been recognized as the bottleneck preventing the development of high-efficiency light-emitting-diodes (LEDs). In this contribution, the influences of 193 nm pulsed laser annealing on the structure, electrical, and optical properties of p-type GaN were systematically analyzed. The hole concentration of p-GaN first increases and then decreases with increasing laser fluence, regardless of post-growth thermal annealing. The effective dopant activation due to laser annealing can be attributed to the dissociation of Mg–H complexes during the treatment. Laser-annealed p-GaN was utilized in a 280 nm deep ultraviolet LED. A maximum of 1.47 times higher wall-plug-efficiency enhancement factor was obtained compared to that without laser annealing, demonstrating that 193 nm laser annealing plays a decisive role in the boosting of quantum efficiency of optoelectronic devices. [ABSTRACT FROM AUTHOR]

Benzo(a)pyrene (BaP) is a representative polycyclic aromatic hydrocarbon (PAH) compound, which has been implicated in cancer initiation and promotion. Although BaP is one of the most extensively studied pollutants, the underlying mechanisms through which BaP affects reactive oxygen species (ROS)/hypoxia-inducible factor 1α (HIF-1α)/heme oxygenase 1(HO-1) signaling during lung or breast carcinogenesis are not yet fully understood. In this study, we analyzed the effects of 0 (control), 1, 5, or 25 µM BaP exposure on A549 and MCF-7 cancer cells, by evaluating cell viability, cell cycle, and regulatory protein expression, metabolic gene expression, and ROS/HIF-1α/HO-1 signaling. Cell viability increased following exposure to 1 and 5 µM BaP in A549 cells but decreased following exposure to all concentrations of BaP in MCF-7 cells. BaP significantly increased the proportions of cells in S and G2/M phases, with concomitant reductions in the proportions of cells in G0/G1 phase, following 5 and 25 µM exposure, which was accompanied by the upregulation of the regulatory proteins cyclin A, cyclin B, cyclin-dependent kinase (CDK)1, and CDK2. The subsequent upregulation of cytochrome p450 (CYP)1A1, CYP1B1, CYP3A4, epoxide hydrolase (EH), aldo-keto reductase (AKRC1) expression, and the attenuation of multi-drug resistance protein 4 (MRP4), glutathione-S-transferase (GST)1A1, and GST1B1 were also observed in both cell lines. Moreover, the induction of ROS and the modulation of HIF-1α and HO-1 were observed after BaP exposure. Taken together, these findings suggest that BaP affects proliferation with reference to metabolic genes and ROS/HIF-1α/HO-1 signaling in A549 and MCF-7 cancer cells. [ABSTRACT FROM AUTHOR]

Objective: Fluoride (F)-releasing restoratives typically are either weak mechanically or release only low levels of F ions. The objectives of this study were to: (1) develop a novel photo-cured nanocomposite with strong mechanical properties and high levels of sustained F ion release via a two-step "co-precipitation + spray-drying" technique to synthesize CaF 2 nanoparticles (nCaF 2 ); and (2) investigate the effect of spray-drying treatment after co-precipitation of nCaF 2 on mechanical properties and F ion release of composite., Methods: Two types of CaF 2 particles were synthesized: A co-precipitation method yielded CaF 2 cp; "co-precipitation + spray-drying" yielded nCaF 2 cpsd. Composites were fabricated with fillers of: (1) 0% CaF 2 + 70% glass; (2) 10% CaF 2 cp + 60% glass; (3) 15% CaF 2 cp + 55% glass; (4) 20% CaF 2 cp + 50% glass; (5) 10% nCaF 2 cpsd + 60% glass; (6) 15% nCaF 2 cpsd + 55% glass; and (7) 20% nCaF 2 cpsd + 50% glass. A commercial F-releasing nanocomposite served as control., Results: The nCaF 2 cpsd had much smaller particle size (median = 32 nm) and narrower distribution (22-57 nm) than CaF 2 cp (median = 5.25 μm, 162 nm-67 μm). The composite containing nCaF 2 cpsd had greater flowability, flexural strength, elastic modulus and hardness than CaF 2 cp composite and commercial control composite. At 84-day immersion in water, the nanocomposites containing 20% nCaF 2 cpsd had 65 times higher cumulative F release, and 77 times greater long-term F-release rate, than commercial control., Conclusions: A novel two-step "co-precipitation + spray-drying" technique of synthesizing nCaF 2 was developed. The photo-cured nanocomposite containing 20% nCaF 2 cpsd possessed strong mechanical properties and excellent long-term F-release ability, and hence is promising for dental restoration applications to inhibit secondary caries., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)