Microwave photonic signal generation in an optically injected discrete mode semiconductor laser

This article belongs to the Special Issue Microwave Photonics Applications.In this paper, microwave photonic signal generation based on the period-one dynamic of optically injected discrete mode (DM) semiconductor lasers has been experimentally demonstrated and numerically simulated. The results show that the frequency of the generated microwave increases linearly with the frequency detuning or optical injection ratio. In addition, a single optical feedback loop is sufficient to reduce the microwave linewidth without significantly deteriorating side mode suppression. The simulation results using a model considering the nonlinear dependencies of the carrier recombination agree well with the experimental results, which indicates that the nonlinear carrier recombination effect is important in determining the nonlinear dynamics of optically injected DM lasers.This research was funded in part by the DESTINI project (2017/COL/007) funded by the ERDF under the SMART Expertise scheme; in part by the DSP Centre (82085) funded by the ERDF through the Welsh Government; and in part by Ministerio de Ciencia e Innovación, Spain, under grant RTI2018-094118-B-C22 MCIN/AEI/FEDER, UE.Peer reviewe

Alpha-lipoic acid induces apoptosis in hepatoma cells via the PTEN/Akt pathway

AbstractWe report here that alpha-lipoic acid (α-LA), a naturally-occurring antioxidant, scavenges reactive oxygen species (ROS) followed by an increase in apoptosis of human hepatoma cells. Apoptosis induced by α-LA was dependent upon the activation of the caspase cascade and the mitochondrial death pathway. α-LA induced increases in caspase-9 and caspase-3 but had no significant effect on caspase-8 activity. Apoptosis induced by α-LA was found to be mediated through the tensin homologue deleted on chromosome 10 (PTEN)/Akt pathway. Prior to cell apoptosis, PTEN was activated and its downstream target Akt was inhibited. Our findings indicate that increasing ROS scavenging could be a therapeutic strategy to treat cancer

2-Cyano-N,N-dimethyl­acetamide

In the crystal structure of the title compound, C5H8N2O, mol­ecules are linked by weak C—H⋯O hydrogen bonds, forming a three-dimensional network

Intramolecular π Stacking in Cationic Iridium(III) Complexes with Phenyl-Functionalized Cyclometalated Ligands: Synthesis, Structure, Photophysical Properties, and Theoretical Studies

The syntheses of two new heteroleptic cationic iridium complexes containing 2,6-diphenylpyridine (Hdppy) and 2,4,6-triphenylpyridine (Htppy) as the cyclometalated ligands, namely, [Ir(dppy)2phen]PF6 (1, phen = 1,10-phenanthroline) and [Ir(tppy)2phen]PF6 (2), are described. The X-ray crystal structure of 2 reveals a distorted octahedral geometry around the Ir center and close intramolecular face-to-face π–π stacking interactions between the pendant phenyl rings at the 2-position of the cyclometalated ligands and the NN ancillary ligand. This represents a new π–π stacking mode in charged Ir complexes. Complexes 1 and 2 are green photoemitters: their photophysical and electrochemical properties are interpreted with the assistance of density functional theory (DFT) calculations. These calculations also establish that the observed intramolecular interactions cannot effectively prevent the lengthening of the Ir–N bonds of the complexes in their metal-centered (3MC) states. Complexes 1 and 2 do not emit light in light-emitting electrochemical cells (LECs) under conditions in which the model compound [Ir(ppy)2phen]PF6 (3) emits strongly. This is explained by degradation reactions of the 3MC state of 1 and 2 under the applied bias during LEC operation facilitated by the enhanced distortions in the geometry of the complexes. These observations have important implications for the future design of complexes for LEC applications

Protection effect of Emodin pretreatment on intestinal I-RI damage of intestinal mucosa in ratsa

AbstractObjectiveTo tinvestigate the protective effect and mechanism of emodin pretreatment on intestinal mucosa of rats with intestinal ischemia-reperfusion injury.MethodsA total of 50 SD rats were randomly divided into control group, model group, emodin groups of low, medium and high dose, with 10 in each group. Ischemia-reperfusion injury (I-RI) mode was established by using noninvasive clamp on superior mesentericartery (SMA). Control group and model group were pretreated with 0.5% sodium carboxymethyl cellulose solution lavage 2 h before operation, emodin groups of low, medium and high dose were given emodin lavage with 20, 40, 60 mg/kg pretreatment, femoral venous blood before the lavage pretreatment (T0) and 1 h ischemia (T1), and inferior vena venous blood after 1 h of reperfusion (T2) were extracted from each group of rats for detection of serum level of intestinal fatty acid binding protein (I-FABP), tumor necrosis factor (TNF-α), endotoxin, interleukin 6 (IL-6), and the content of diamine oxidase (DAO); After model establishment, the rats were sacrificed, intestine homogenate was prepared by using blind intestinal tissue to detect intestinal tissue myeloperoxidase (MPO), malondialdehyde (MDA) and superoxide dismutase (SOD) levels. And upper small intestine tissue was retrieved, followed by fixation and conventional HE staining to observe intestinal tissue morphology under light microscopy.ResultsIn emodin groups of low, medium and high dose at T1 and T2, I-FABP, TNF-α, endotoxin, IL-6 and DAO level were significantly lower than that of model group (P<0.05); in emodin group of low, medium and high dose, MPO and MDA content in intestinal tissue homogenate was significantly lower than that in model group (P<0.05), SOD level was significantly higher than that of model group (P<0.05). Intestinal damage of emodin low, medium and high dose groups were significantly lighter than model group.ConclusionsEmodin pretreatment has certain protective effect on intestinal mucosa in ischemia reperfusion injury