Quantification and pharmacokinetics of Taiwanin E methyl ether in rats by liquid chromatography–tandem mass spectrometry

This study firstly describes the development of an accurate and sensitive high‐performance liquid chromatography–tandem mass spectrometry (LC‐MS/MS) assay for the quantification of Taiwanin E methyl ether (TEME) in rat plasma. The assay involved a simple liquid–liquid extraction step with ethyl acetate and a gradient elution using a mobile phase consisting of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid. Chromatographic separation was successfully achieved on an Agilent Zorbax‐C₁₈ column (2.1 × 50 mm, 3.5 µm) with a flow rate of 0.40 mL/min. The multiple reaction monitoring was based on the transitions of m/z = 379.1 → 320.1 for TEME and 386.1 → 122.0 for buspirone (internal standard). The assay was validated to demonstrate the specificity, linearity, recovery, accuracy, precision and stability. The lower limit of quantification was 0.50 ng/mL in 50 μL of rat plasma. The developed and validated method was successfully applied to the quantification and pharmacokinetic study of TEME in rats after intravenous and oral administration of 1.45 mg/kg TEME. The oral absolute bioavailability of TEME was estimated to be 5.85 ± 1.41% with an elimination half‐life value of 2.61 ± 0.55 h, suggesting its poor absorption and/or strong metabolism in vivo. Copyright © 2012 John Wiley & Sons, Ltd.     

Fast analysis of triterpenoids in Ganoderma lucidum spores by ultra‐performance liquid chromatography coupled with triple quadrupole mass spectrometry

A rapid and reliable method was established for simultaneous determination of main triterpenoids in Ganoderma lucidum spores using ultra‐high‐performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC‐TQ‐MS). The established method was validated in terms of linearity, sensitivity, precision, accuracy and stability, and was successfully applied to determine the contents of 10 main triterpenoids in different batches of G. lucidum spores. The analysis results showed that moderate levels of triterpenoids were found in G. lucidum spores. In addition, a MS full scan with a daughter ion scan experiment was performed to identify the potential derivatives of triterpenoids present in G. lucidum spores. As a result, a total of 22 triterpenoids from different G. lucidum spores were unequivocally or tentatively identified via comparisons with authentic standards and literatures. This method provides both qualitative and quantitative results without the need for repetitive UPLC‐MS analyses, thereby increasing efficiency and productivity, making it suitable for high‐throughput applications. Copyright © 2013 John Wiley & Sons, Ltd.     

Binary hairy nanoparticles: Recent progress in theory and simulations

Binary polymer brushes, including mixed homopolymer brushes and diblock copolymer brushes, are an attractive class of environmentally responsive nanostructured materials. Owing to microphase separation of the two chemically distinct components in the brush, multifaceted nanomaterials with functionalized and patterned surfaces can be obtained. This review summarizes recent progress on the theory and simulations related to binary polymer brushes grafted to flat, spherical, and cylindrical substrates, with a focus on patterned morphologies of multifaceted hairy nanoparticles, an intriguing class of hybrid nanostructured particles (e.g., nanospheres and nanorods). In particular, powerful field theory and particle-based simulations suitable for revealing novel structures on these patterned surfaces, including self-consistent field theory and dissipative particle dynamics simulations, are emphasized. The unsolved yet critical issues in this research field, such as dynamic response of binary polymer brushes to environmental stimuli and the hierarchical self-assembly of binary hairy nanoparticles, are briefly discussed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1583–1599     

Characterization of the chemical constituents in Hongjingtian injection by liquid chromatography quadrupole time‐of‐flight mass spectrometry

Hongjingtian injection is made from Rhodiola wallichiana and used in the treatment of stable angina pectoris associated with coronary heart disease. In this study, the chemical constituents in Hongjingtian injection were comprehensively studied using liquid chromatography quadrupole time‐of‐flight mass spectrometry. A total of 49 compounds were identified or assumed, including 10 organic acids, nine phenylethanoids, 10 phenylpropanoids, two flavonoid glycosides, seven monoterpene glycosides, seven octylglycosides and four other types of compounds. The structures of seven compounds were confirmed by comparing their retention times, MS and UV spectra with the corresponding authentic standards. Amongst the 49 compounds, 35 were firstly found in R. wallichiana, while they have been reported in other species of the genus Rhodiola, including Rhodiola crenulata, Rhodiola sacra, Rhodiola rosea and Rhodiola kirilowii. The possible fragmentation pathways in the mass spectrometry of the major types of compounds are proposed and summarized. Our study demonstrates a rapid method for characterizing the chemical constituents present in the Hongjingtian injection, which could also be applied to the identification of chemical constituents in other TCM formulae containing R. wallichiana.     

Graphyne-oxide supported Pd catalyst with ten times higher nitrobenzenes reduction activity than Pd/C

Research on Chemical Intermediates - Upon oxidation, a graphyne-like porous carbon-rich network (GYLPC), which is a two-dimensional carbon material consisting of sp- and sp2-hybridized carbon atoms...     

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.     

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.