Synthesis and anticancer activities of diquinazoline diselenides compounds

A series of novel diquinazoline diselenide compounds was designed and synthesized with substituted 4-chloroquinazoline and sodium diselenide. Their structures were confirmed by IR, 1H NMR, 13C NMR, and elemental analyses.The antitumor activity of the new compounds was evaluated by MTT method. Compound 1a, 1c, 1h and 1i were found to have activities against MDA-MB-435, A549,MDA-MB-231, SiHa, and HeLa cells. Moreover, compared with the commercial anticancer drugs Gefitinib, Oxaliplatin,Taxol, 10-Hydroxycamptothec in, and Epirubicin Hydrochloride,1a exerted better antitumor effects on corresponding cell lines at 10 μM

Synthesis and Antioxidant Activity of Cationic 1,2,3-Triazole Functionalized Starch Derivatives

In this study, starch was chemically modified to improve its antioxidant activity. Five novel cationic 1,2,3-triazole functionalized starch derivatives were synthesized by using "click" reaction and N-alkylation. A convenient method for pre-azidation of starch was developed. The structures of the derivatives were analyzed using FTIR and H-1 NMR. The radicals scavenging abilities of the derivatives against hydroxyl radicals, DPPH radicals, and superoxide radicals were tested in vitro in order to evaluate their antioxidant activity. Results revealed that all the cationic starch derivatives (2a-2e), as well as the precursor starch derivatives (1a-1e), had significantly improved antioxidant activity compared to native starch. In particular, the scavenging ability of the derivatives against superoxide radicals was extremely strong. The improved antioxidant activity benefited from the enhanced solubility and the added positive charges. The biocompatibility of the cationic derivatives was confirmed by the low hemolytic rate (<2%). The obtained derivatives in this study have great potential as antioxidant materials that can be applied in the fields of food and biomedicine

A low phase noise high power Er-fiber frequency comb synchronized to the hydrogen maser clock by harmonic phase locking

We demonstrate a low phase noise all polarization-maintaining (PM) Er-fiber optical frequency comb (OFC) with low phase noise, which is synchronized to the hydrogen maser clock (HMC) using the 18th harmonic of the repetition rate for tight phase locking. The instability of the locked carrier envelope offset frequency is 1.24 × 10−18@1 s, the phase noise of the OFC is −96 dBc/Hz at 1 Hz offset, and the corresponding RMS timing jitter of the repetition rate is 62 fs (1 Hz–1 MHz). The residual frequency instability of the repetition rate (200 MHz) is 1.46 × 10−14@1 s, and the residual phase noise of the OFC normalized to 10 MHz is −138 dBc/Hz at 1 Hz offset and declines to about −160 dBc/Hz at the far-end, much lower than that of the HMC (−122 dBc/Hz at 1 Hz and −156 dBc/Hz at the far-end)

Detection of limited-energy α particles using CR-39 in laser-induced p −11B reaction

Due to the harsh radiation environment produced by strong laser plasma, most of the detectors based on semiconductors cannot perform well. So, it is important to develop new detecting techniques with higher detection thresholds and highly charged particle resolution for investigating nuclear fusion reactions in laser-plasma environments. The Columbia Resin No. 39 (CR-39) detector is mainly sensitive to ions and insensitive to the backgrounds, such as electrons and photons. The detector has been widely used to detect charged particles in laser-plasma environments. In this work, we used a potassium–ethanol–water (PEW) etching solution to reduce the proton sensitivity of CR-39, by raising the detection threshold for the research of laser-induced 11B(p, α)2α reaction. We calibrated the 3–5 MeV α particles in an etching condition of 60°C PEW-25 solution (17% KOH + 25%C2H5OH + 58%H2O) and compared them with the manufacturer’s recommended etching conditions of 6.25 N NaOH aqueous solution at 98°C in our laser-induced nuclear reaction experiment. The results indicate, with the PEW-25 solution, that CR-39 is more suitable to distinguish α tracks from the proton background in our experiment. We also present a method to estimate the minimum detection range of α energy on specific etching conditions in our experiment