Computational insight into asymmetric uranyl‐salophen coordinated with α, β‐unsaturated aldehydes and ketones

The study of the catalytic activity and activation mechanism of asymmetric uranyl‐salophens with α, β‐unsaturated aldehydes or α, β‐unsaturated ketones, is a research hotspot. In this paper, the complexes of the uranyl–salophen(U‐S) modified by unilateral benzene, coordinated with cyclohexenone, cyclopentenone and acrolein, were investigated using density functional theory calculations at the level of B3LYP/6‐311G(d, p) basis set. The results showed that the uranyl‐salophen(U‐S) weakened the large π bond between C = C and C = O of the α, β‐unsaturated aldehydes and ketones, making the unsaturated aldehydes and ketones activated. In addition, the molecular‐recognition selectivity of the asymmetrical uranyl‐salophen for cyclohexenone and cyclopentenone were much higher than for acrolein.     

Electrochemical Tri- and Difluoromethylation-Triggered Cyclization Accompanied by the Oxidative Cleavage of Indole Derivatives

Considering their unique roles in organic synthesis, and pharmaceutical and agrochemical applications, the development of fluoroalkylation, cyclization, and indole oxidative cleavage are important topics. Herein, an unprecedented electrochemical tri- and difluoromethylation/cyclization/indole oxidative cleavage process occurring in an undivided cell is presented. The protocol employs a readily prepared Langlois reagent as the fluoroalkyl source, affording a series of tri- or difluoromethylated 2-(2-acetylphenyl)isoquinoline-1,3-diones in good yields with excellent stereoselectivity. It is worth noting that this new methodology merges the fluoroalkylation/cyclization of N-substituted acrylamide alkenes with the oxidative cleavage of an indole C(2)=C(3) bond under external oxidant-free conditions.     

A Dynamical Phase Transition of Binary Species BECs Mixtures in a Double Well Potential

We investigate the critical behavior in tunneling dynamics of a binary mixture of Bose-Einstein condensates (BECs) trapped in a symmetric double well potential. By gradually increasing the interspecies interaction, we characterize a continuous dynamical phase transition behavior which involves power law scaling. This dynamical phase transition is a consequence of separatrix crossing as we revealed by poincaré section analysis.     

Infrared imaging as a means of visually characterizing the thermoacoustic onset process influenced by a Helmholtz resonator

A Helmholtz resonator can be used as a transmission part to connect the thermoacoustic engine (TE) with its load. However, the resonator can significantly influence the performance of the TE. In order to investigate the impact of a Helmholtz resonator on the onset process of a TE, infrared (IR) imaging is firstly used as a visualization method to characterize the onset mechanism. The influence of dimensions of the Helmholtz resonator on the onset process are analyzed experimentally and theoretically. Results show that the Helmholtz resonator reduces the pressure amplitude at the onset moment and increases the onset temperature of the TE, both of which depend on the acoustic power absorbed from the TE. Onset without a sudden increase of pressure amplitude is observed with the Helmholtz resonator at resonance length. This paper shows that IR imaging is an effective way to characterize the temperature distribution in a TE study.     

LC–MS/MS determination and interaction of the main components from the traditional Chinese drug pair Danshen–Sanqi based on rat intestinal absorption

The Chinese drug pair Danshen (Salvia miltiorrhiza)–Sanqi (Panax ginseng) has been widely used for centuries treating various cardiovascular disorders, among which salvianlic acid B (SAB), ginsenoside Rg₁ (GRg₁), ginsenoside Rb₁ (GRb₁) and notoginsenoside R₁ (NGR₁) were identified as the major components. The present study focused on the interaction between these components based on investigating their intestinal absorption using the Ussing chamber technique. The concentrations of SAB, GRg₁, GRb1 and NGR₁ in the intestinal perfusate were determined by LC–MS/MS method, followed by Q (accumulative quantity) and P_app (apparent permeability). The results showed that all these four main components displayed very low permeabilities, which implied their poor absorption in the rat intestine. The intestinal absorption level of SAB displayed regioselectivity: duodenum < jejunum < ileum. However, there was no significant difference in the absorption of GRg₁ and GRb₁ in the different segments. The Q and P_app values of the four main components were obviously increased in jejunum when co‐administrating Danshen extract with Sanqi extract. In conclusion, compatibility of Danshen and Sanqi could remarkably improve the intestinal absorption level of the main components in the pair. To some extent, this might explain the nature of the compatibility mechanisms of composite formulae in TCMs.     

A group adaptive elastic-net approach for variable selection in high-dimensional linear regression

In practice, predictors possess grouping structures spontaneously. Incorporation of such useful information can improve statistical modeling and inference. In addition, the high-dimensionality often leads to the collinearity problem. The elastic net is an ideal method which is inclined to reflect a grouping effect. In this paper, we consider the problem of group selection and estimation in the sparse linear regression model in which predictors can be grouped. We investigate a group adaptive elastic-net and derive oracle inequalities and model consistency for the cases where group number is larger than the sample size. Oracle property is addressed for the case of the fixed group number. We revise the locally approximated coordinate descent algorithm to make our computation. Simulation and real data studies indicate that the group adaptive elastic-net is an alternative and competitive method for model selection of high-dimensional problems for the cases of group number being larger than the sample size.     

Resolving quantum dots and peptide assembly and disassembly using bending capillary electrophoresis

Despite the numerous techniques developed for the studying nanoparticle and peptide interaction nowadays, sensitive and convenient assay in the process of flow, especially to simulate the self‐assembly of quantum dots (QDs) and peptide inflow in blood vessels, still remains big challenges. Here, we report a novel assay for studying the self‐assembly of QDs and peptide, based on CE using a bending capillary. We demonstrate that the semicircles numbers of the bending capillary affect the self‐assembly kinetics of CdSe/ZnS QDs and ATTO‐D₃LVPRGSGP₉G₂H₆ peptide. Moreover, benefitting from this novel assay, the effect of the position on the self‐assembly has also been realized. More importantly, we also demonstrate that this novel assay can be used for studying the stability of the QDs–peptide complex inflow. We believe that our novel assay proposed in this work could be further used as a general strategy for the studying nanoparticle–biomolecule interaction or biomolecule–biomolecule interaction.     

An LC–MS/MS method for quantification of HR011303, a novel highly selective urate transporter 1 inhibitor in beagle dogs and the application to a pharmacokinetic study

HR011303 is a novel and highly selective urate transporter 1 (URAT1) inhibitor. In this study, a sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for quantification of HR011303 in beagle dog plasma. Plasma samples were pretreated with protein‐precipitation extraction by acetonitrile and added with a trifluoromethyl substituted analog of HR011303 as internal standard. The chromatographic separation was performed on a Shiseido C₁₈ column (100 × 4.6 mm, i.d., 5 μm) by mobile phases consisting of 5 mm ammonium–formic acid (100:0.1) and acetonitrile–formic acid (100:0.1) solutions in gradient elution. The MS detection was conducted in electrospray positive ionization with multiple reactions monitoring at m/z 338 → 240 for HR011303 and m/z 328 → 230 for the internal standard using 25 eV argon gas collision induced dissociation. The established LC–MS/MS method showed good selectivity, sensitivity, precision and accuracy. The plasma pharmacokinetics of HR011303 in beagle dogs following both oral and intravenous administration were then successfully evaluated using this LC–MS/MS method.