Improved Design of Slope-Shaped Hole-Blocking Layer and Electron-Blocking Layer in AlGaN-Based Near-Ultraviolet Laser Diodes.

The injection and leakage of charge carriers have a significant impact on the optoelectronic performance of GaN-based lasers. In order to improve the limitation of the laser on charge carriers, a slope-shape hole-barrier layer (HBL) and electron-barrier layer (EBL) structure are proposed for near-UV (NUV) GaN-based lasers. We used Crosslight LASTIP for the simulation and theoretical analysis of the energy bands of HBL and EBL. Our simulations suggest that the energy bands of slope-shape HBL and EBL structures are modulated, which could effectively suppress carrier leakage, improve carrier injection efficiency, increase stimulated radiation recombination rate in quantum wells, reduce the threshold current, improve optical field distribution, and, ultimately, improve laser output power. Therefore, using slope-shape HBL and EBL structures can achieve the superior electrical and optical performance of lasers.

Citrinin Monomer and Dimer Derivatives with Antibacterial and Cytotoxic Activities Isolated from the Deep Sea-Derived Fungus Penicillium citrinum NLG-S01-P1.

Two previously unreported citrinin dimer derivatives, penicitol D (1) and 1-epi-citrinin H1 (2), were isolated from the culture of a deep sea-derived fungus Penicillium citrinum NLG-S01-P1, together with 11 biogenetic related compounds (3⁻13). A plausible biogenetic pathway for compounds 2⁻4 was proposed. Their structures, including absolute configurations, were established through analysis of extensive spectroscopic data and time-dependent density functional theory (TD-DFT) ECD calculations. Compounds 1 and 2 showed antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA). Compounds 5 and 10 displayed relatively stronger activities than the other compounds against Vibrio vulnificus and Vibrio campbellii. Compound 1 showed the most potent cytotoxic activity towards the HeLa cell.

Secondary metabolites isolated from the deep sea-derived fungus Aspergillus sydowii C1-S01-A7.

Two novel compounds, 2-hydroxy-6-formyl-vertixanthone (1) and 12-O-acetyl-sydowinin A (2), were obtained from the culture of a deep sea-derived fungus Aspergillus sydowii C1-S01-A7, together with twenty-two known compounds (3-24). Their structures were elucidated based on extensive spectroscopic methods. Compounds 4, 8 and 12 showed antibacterial activities against Vibrio rotiferianus and Vibrio vulnificus. Compounds 1, 2, 7, 8, 11 and 12 exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus. Remarkably, compound 8 displayed selectively cytotoxic activity against A549 and strongest cytotoxic activities for both A549 and HepG2 in comparison to the remaining compounds.

Chlorinated Azaphilone Pigments with Antimicrobial and Cytotoxic Activities Isolated from the Deep Sea Derived Fungus Chaetomium sp. NA-S01-R1.

Four novel compounds, chaephilone C (1), chaetoviridides A-C (2-4), were obtained from the culture of a deep sea derived fungus Chaetomium sp. NA-S01-R1, together with four known compounds-chaetoviridin A (5), chaetoviridine E (6), chaetomugilin D (7) and cochliodone A (8). Their structures, including absolute configurations, were assigned based on NMR, MS and time-dependent density functional theory (TD-DFT) ECD calculations. A plausible biogenetic pathway for compounds 1-3 was proposed. Compounds 2 and 3 exhibited antibacterial activities against Vibrio rotiferianus and Vibrio vulnificus. Compounds 1, 3 and 4 displayed similar anti-methicillin resistant Staphylococcus aureus (anti-MRSA) activities in comparison to chloramphenicol. Compound 2 showed the most potent cytotoxic activities towards the Hep G2 cell and compounds 1 and 3 demonstrated relatively stronger cytotoxic activities than the other compounds against the HeLa cell.