Enhancing acid orange II degradation in ozonation processes with CaFe2O4 nanoparticles as a heterogeneous catalyst.

This study used CaFe2O4 nanoparticles as a catalyst for ozonation processes to degrade Acid Orange II (AOII) in aqueous solution. The study compared heterogeneous catalytic ozonation (CaFe2O4/O3) with ozone treatment alone (O3) at different pH values (3-11), catalyst dosages (0.25-2.0 g L-1), and initial AOII concentrations (100-500 mg L-1). The O3 alone and CaFe2O4/O3 systems nearly completely removed AOII's color. In the first 5 min, O3 alone had a color removal efficiency of 75.66%, rising to 92% in 10 min, whereas the CaFe2O4/O3 system had 81.49%, 94%, and 98% after 5, 10, and 20 min, respectively. The O3 and CaFe2O4/O3 systems degrade TOC most efficiently at pH 9 and better with 1.0 g per L CaFe2O4. TOC removal effectiveness reduced from 85% to 62% when the initial AOII concentration increased from 100 to 500 mg L-1. The study of degradation kinetics reveals a pseudo-first-order reaction mechanism significantly as the solution pH increased from 3 to 9. Compared to the O3 alone system, the CaFe2O4/O3 system has higher k values. At pH 9, the k value for the CaFe2O4/O3 system is 1.83 times higher than that of the O3 alone system. Moreover, increasing AOII concentration from 100 mg L-1 to 500 mg L-1 subsequently caused a decline in the k values. The experimental data match pseudo-first-order kinetics, as shown by R2 values of 0.95-0.99. AOII degradation involves absorption, ozone activation, and reactive species production based on the existence of CaO and FeO in the CaFe2O4 nanocatalyst. This catalyst can be effectively recycled multiple times.

Anti-cancer activity of Marsdenialongise A, a new C21 steroidal glycoside isolated from Marsdenia longipes W.T. Wang (Apocynaceae).

C21 steroidal glycosides are a group of natural compounds with biological activities such as anti-cancer, anti-microbial, and anti-viral properties. In this study, we isolated and determined the structure of a new C21 steroidal glycoside, named Marsdenialongise A from Marsdenia longipes W.T. Wang, using nuclear magnetic resonance spectroscopy and mass spectra data. Marsdenialongise A is a derivative of tenacigenin B and was isolated for the first time from a plant. The inhibitory effect of Marsdenialongise A on cancer cells was evaluated through MTT and cell migration assays, cell cycle, and apoptosis analyses. The results of the MTT assay showed that Marsdenialongise A reduces the cell viability of cancer cells, with the AGS cell line being more sensitive than other cell lines, with an IC50 value of 5.69 µM (for 48 h of treatment). Marsdenialongise A also exhibited an ability to prevent the migration of cancer cells in AGS cells. Further analysis using flow cytometry has revealed that Marsdenialongise A is capable of inducing cell cycle arrest and apoptosis. The overexpression of reactive oxygen species (ROS) production induced by Marsdenialongise A can be considered a cause that leads to the influence on the cell cycle and apoptosis of cancer cells. Thus, Marsdenialongise A can be considered a potential anti-cancer agent.

Effects of Autoionizing Resonances on Wave-Packet Dynamics Studied by Time-Resolved Photoelectron Spectroscopy.

We report a combined experimental and theoretical study on the effect of autoionizing resonances in time-resolved photoelectron spectroscopy. The coherent excitation of N_{2} by ∼14.15 eV extreme-ultraviolet photons prepares a superposition of three dominant adjacent vibrational levels (v^{'}=14-16) in the valence b^{'} ^{1}Σ_{u}^{+} state, which are probed by the absorption of two or three near-infrared photons (800 nm). The superposition manifests itself as coherent oscillations in the measured photoelectron spectra. A quantum-mechanical simulation confirms that two autoionizing Rydberg states converging to the excited A ^{2}Π_{u} and B ^{2}Σ_{u}^{+} N_{2}^{+} cores are accessed by the resonant absorption of near-infrared photons. We show that these resonances apply different filters to the observation of the vibrational wave packet, which results in different phases and amplitudes of the oscillating photoelectron signal depending on the nature of the autoionizing resonance. This work clarifies the importance of resonances in time-resolved photoelectron spectroscopy and particularly reveals the phase of vibrational quantum beats as a powerful observable for characterizing the properties of such resonances.

Anti-cancer activity of green synthesized silver nanoparticles using Ardisia gigantifolia leaf extract against gastric cancer cells.

Using extracts from herbs for silver nanoparticle synthesis is attracting attention for its anticancer activity. Ardisia gigantifolia is a herb used in traditional Chinese medicine for treating stomach ailments, and some compounds isolated from this plant exhibit the inhibitory activity against different cancer cells. However, the synthesis of silver nanoparticle using extract of Ardisia gigantiflia leaves and their anti-cancer activity was not reported. In this report, the green synthesized silver nanoparticles using Ardisia gigantiflia extract (Arg-AgNPs) has average diameter of 6 nm with functional groups including O-H, C-H, and CO founded on the surface of these nanoparticles. The viability assays results revealed Arg-AgNPs reduced gastric cancer cell proliferation in a dose-dependent manner, with IC50 values of 1.37 and 0.65 µg/mL for AGS cells and 1.03 and 0.96 µg/mL for MKN45 cells. Arg-AgNPs caused cell cycle arrest at the G0/G1 phase and suppressed cell migration. Additionally, Arg-AgNPs significantly increased the percentage of senescent cells and promoted overproduction of reactive oxygen species (ROS) compared to the control. Thus, this study indicates that Arg-AgNPs can be considered as a promising candidate against human gastric cancer cells.

Odd-even harmonic generation from oriented CO molecules in linearly polarized laser fields and the influence of the dynamic core-electron polarization.

We present a detailed theoretical study of the odd-even harmonics generated from the polar molecule CO by the method based on numerically solving the time-dependent Schrödinger equation within the single-active-electron approximation. First, we reproduce the pure even harmonic generation of CO predicted theoretically by Hu et al. using the time-dependent density functional theory [H. Hu et al., Phys. Rev. Lett., 2017, 119, 173201]. Then, based on the Floquet approach, we are able to attribute this behavior to the half-cycle mirror symmetry of the molecule-field system when the polar molecule is perpendicular to the laser polarization. By numerical simulations, we show that this symmetry is broken at orientation angles other than 90° resulting in the odd-even harmonic generation and a non-trivial even-to-odd harmonics ratio strongly dependent on the molecular orientation. Furthermore, we investigate the influence of the dynamic core-electron polarization (DCeP) on the odd-even behavior near the cutoff of the high-order harmonic spectra. We emphasize that the DCeP effect is noticeable for the odd harmonics only.