Surface of room temperature ionic liquid [bmim][PF6] studied by polarization- and experimental configuration-dependent sum frequency generation vibrational spectroscopy

Understanding and control of the surface properties such as molecular orientations are of great importance in numerous applications of ionic liquids. However, there remain discrepancies among the previous experimental and theoretical studies on the surface orientation and structures of room temperature ionic liquids(RTIL) systems. In this article, the orientation of 1-butyl-3-methylimidazolium([bmin]) cation at the air/liquid interface of a characteristic RTIL, 1-butyl-3-methylimidazolium hexafluorophosphate([bmim][PF6]), was investigated by the sum frequency generation vibrational spectroscopy(SFG-VS). Detailed polarization and experimental configuration analyses of the SFG-VS spectra showed the possibility of a small spectral splitting in the CH3 symmetric stretching region, which can be further attributed to the probable existence of multiple orientations for the interfacial [bmim] cations. In addition, the(N)–CH3 vibrations were absent, ruling out the prediction by several recent molecular dynamics simulations which state that portions of the [bmim] cations orient with a standing-up(N)–CH3 group at the ionic liquid surface. Hence, new realistic theoretical models have to be developed to reflect the complex nature of the ionic liquid surface.     

Two homosecoiridoids from the fl ower buds of Lonicera japonica

Two new homosecoiridoids, named loniaceticiridoside (1) and lonimalondialiridoside (2), were isolated from an aqueous extract of the flower buds of Lonicera japonica. Their structures including the absolute configuration were determined by extensive spectroscopic studies, especially by 2D NMR and CD data analysis. A proposed biosynthetic pathway and preliminary investigations of the biological activity of compounds 1 and 2 are also discussed.     

Implementing a Two-Photon Three-Degrees-of-Freedom Hyper-Parallel Controlled Phase Flip Gate Through Cavity-Assisted Interactions

Hyper-parallel quantum information processing is a promising and beneficial research field. Herein, a method to implement a hyper-parallel controlled-phase-flip (hyper-CPF) gate for frequency-, spatial-, and time-bin-encoded qubits by coupling flying photons to trapped nitrogen vacancy (NV) defect centers is presented. The scheme, which differs from their conventional parallel counterparts, is specifically advantageous in decreasing against the dissipate noise, increasing the quantum channel capacity, and reducing the quantum resource overhead. The gate qubits with frequency, spatial, and time-bin degrees of freedom (DOF) are immune to quantum decoherence in optical fibers, whereas the polarization photons are easily disturbed by the ambient noise.     

Dynamic Variation of Excitonic Coupling in Excited Bilayer Graphene Quantum Dots?

The intermolecular interaction determines the photophysical properties of the organic aggregates, which are critical to the performance of organic photovoltaics. Here, excitonic coupling, an important intermolecular interaction in organic aggregates, between the π-stacking graphene quantum dots is studied by using transient absorption spectroscopy. We find that the spectral evolution of the ground state bleach arises from the dynamic variation of the excitonic coupling in the excited π-stacks. According to the spectral simulations, we demonstrate that the kinetics of the vibronic peak can be exploited as a probe to measure the dynamics of excitonic coupling in the excited π-stacks.     

Fractional damping enhances chaos in the nonlinear Helmholtz oscillator

Nonlinear Dynamics - The main purpose of this paper is to study both the underdamped and the overdamped dynamics of the nonlinear Helmholtz oscillator with a fractional-order damping. For that...     

A novel LC–MS/MS method for the determination of ziritaxestat in rat plasma and its pharmacokinetic study

Ziritaxestat is a first-in-class autotoxin inhibitor. The purpose of this study was to develop a liquid chromatography/electrospray ionization tandem mass spectrometric (LC–MS/MS) method for the determination of ziritaxestat in rat plasma. The plasma sample was deproteinated using acetonitrile and then separated on an Acquity BEH C₁₈ column with water containing 0.1% formic acid and acetonitrile as mobile phase, which was delivered at 0.4 ml/min. Ziritaxestat and the internal standard (crizotinib) were quantitatively monitored with precursor-to-product transitions of m/z 589.3 > 262.2 and m/z 450.1 > 260.2, respectively. The total running time was 2.5 min. The method showed excellent linearity over the concentration range 0.5–2000 ng/ml, with correlation coefficient >0.9987. The extraction recovery was >82.09% and the matrix effect was not significant. Inter- and intra-day precisions (RSD) were <11.20% and accuracies were in the range of −8.50–7.45%. Ziritaxestat was demonstrated to be stable in rat plasma under the tested conditions. The validated LC–MS/MS method was successfully applied to study the pharmacokinetic profiles of ziritaxestat in rat plasma after intravenous and oral administration. Pharmacokinetic results demonstrated that ziritaxestat displayed a short half-life (~3 h) and low bioavailability (20.52%).     

Comparative absorption kinetics of seven active ingredients of Eucommia ulmoides extracts by intestinal in situ circulatory perfusion in normal and spontaneous hypertensive rats

Eucommia ulmoides Oliv. (E. ulmoides) is a valuable and nourishing medicinal herb in China that has been used in the treatment of hypertension. Given the fact that most traditional Chinese medicine is mainly used to treat disease, investigating the pharmacokinetics of traditional Chinese medicines in the pathological state is more useful than that in the normal state. However, the differences in the absorption kinetics of active ingredients of E. ulmoides extract between pathological and physiological conditions have not been reported. Therefore, in this study, the rat intestinal in situ circulatory perfusion model was used to investigate the differences in absorption kinetics of seven active ingredients of E. ulmoides extract in normal and spontaneously hypertensive rats, namely, genipinic acid, protocatechuic acid, neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, (+)-pinoresinol di-O-β-D -glucopyranoside and (+)-pinoresinol 4′-O-β-D -glucopyranoside. Our results indicate that the pathological state of spontaneous hypertension may change the absorption of active components of E. ulmoides extracts, and these findings may provide a reference for improving the rational use of E. ulmoides in the clinic.