Simultaneous enantioselective determination of omeprazole,rabeprazole, lansoprazole,and pantoprazole enantiomers in human plasma by chiral liquid chromatography–tandem mass spectrometry

Proton pump inhibitors, including omeprazole, rabeprazole, lansoprazole, and pantoprazole, achieved simultaneous enantioselective determination in the human plasma by chiral liquid chromatography–tandem mass spectrometry. The four corresponding stable isotope‐labeled proton pump inhibitors were adopted as the internal standards. Each enantiomer and the internal standards were extracted with acetonitrile containing 0.1% ammonia, then separated with a Chiralpak IC column (5 µm, 4.6 mm × 150 mm) within 10 min. The mobile phase was composed of acetonitrile–ammonium acetate (10 mM) containing 0.2% acetic acid (50:50, v/v). To quantify all enantiomers, an API 4000 tandem mass spectrometer was used, and multiple reaction monitoring transitions were performed on m/z 360.1→242.1, 384.1→200.1, 370.1→252.1, and 346.1→198.1, respectively. No significant matrix effect was observed for all analytes. The calibration curve for all enantiomers were linear from 1.25 to 2500 ng/mL. The precisions for intra‐ and inter‐run were < 14.2%, and the accuracy fell in the interval of –5.3 to 8.1%. Stability of samples was confirmed under the storage and processing conditions. The developed method was also suitable for separation and determination of ilaprazole enantiomers. The validated method combining the equilibrium dialysis method was applied to the protein binding ratio studies of four pairs proton pump inhibitor enantiomers in human plasma.     

Photocatalysis: an overview of recent developments and technological advancements

Photocatalysis,which is the catalyzation of redox reactions via the use of energy obtained from light sources,is a topic that has garnered a lot of attention in recent years as a means of addressing the environmental and economic issues plaguing society today.Of particular interest are photosynthesis can potentially mimic a variety of vital reactions,many of which hold the key to develop sustainable energy economy.In light of this,many of the technological and procedural advancements that have recently occurred in the field are discussed in this review,namely those linked to:(1)photocatalysts made from metal oxides,nitride,and sulfides;(2)photocatalysis via polymeric carbon nitride(PCN);and(3)general advances and mechanistic insights related to TiO2-based catalysts.The challenges and opportunities that have arisen over the past few years are discussed in detail.Basic concepts and experimental procedures which could be useful for eventually overcoming the problems associated with photocatalysis are presented herein.     

Tuning Magnetic Anisotropy in a Class of Co(II) Bis(hexafluoroacetylacetonate) Complexes

Tuning the magnetic anisotropy of metal ions remains highly interesting in the design of improved single‐molecule magnets (SMMs). We herein report synthetic, structural, magnetic, and computational studies of four mononuclear Co^II complexes, namely [Co(hfac)₂(MeCN)₂] ( 1 ), [Co(hfac)₂(Spy)₂] ( 2 ), [Co(hfac)₂(MBIm)₂] ( 3 ), and [Co(hfac)₂(DMF)₂] ( 4 ) (MeCN=acetonitrile, hfac=hexafluoroacetylacetone, Spy=4‐styrylpyridine, MbIm=5,6‐dimethylbenzimidazole, DMF=N,N‐dimethylformamide), with distorted octahedral geometry constructed from hexafluoroacetylacetone (hfac) and various axial ligands. By a building block approach, complexes 2 – 4 were synthesized by recrystallization of the starting material of 1 from various ligands containing solution. Magnetic and theoretical studies reveal that 1 – 4 possess large positive D values and relative small E parameters, indicating easy‐plane magnetic anisotropy with significant rhombic anisotropy in 1 – 4 . Dynamic alternative current (ac) magnetic susceptibility measurements indicate that these complexes exhibit slow magnetic relaxation under external fields, suggesting field‐induced single‐ion magnets (SIMs) of 1 – 4 . These results provide a promising platform to achieve fine tuning of magnetic anisotropy through varying the axial ligands based on Co(II) bis(hexafluoroacetylacetonate) complexes.     

阻尼对空爆荷载等效静载动力系数的影响

为考查阻尼参数对空爆荷载等效静载动力系数的影响,理论推导了空爆荷载下结构等效单自由体系弹塑性位移解及延性比解,设计并计算了阻尼比0.000 1～0.1、延性比1～4的20种典型工况的动力系数,并与现行抗爆设计规范动力系数公式结果进行了对比。结果表明:阻尼比小于0.000 1时可基本代表无阻尼状态,阻尼比0.01的动力系数比无阻尼的最大降低幅度为2.08%,数值差异很小,因此阻尼比为0.01以内时,可忽略阻尼对动力系数的影响;阻尼比0.05的动力系数比无阻尼的降低幅度约9.92%,数值差异较大,认为阻尼比0.05以上时将具有明显的经济效益;现行设计规范动力系数更适用于柔性结构体系,运用于刚性结构抗爆设计时,计算误差较大,对阻尼比较小的结构设计更不利。     

Time‐dependent Density Functional Theory Study on the Hydrogen‐bonded Dimers Formed by Gauche‐1PA and Trans‐1PA

Three hydrogen bonding complexes of the gauche‐1PA dimer (GG), trans‐1PA dimer (TT) and mixed dimer (GT) have been calculated for the geometry conformations and excited‐state energies. The electron distribution at the site of C‐O of H‐donor moiety in HOMO transfers to the direction of O‐H of H‐acceptor moiety in LUMO. The hydrogen bond between two 1PAs is the bridge of the intermolecular charge transfer. By the Zhao and Han's excited‐state hydrogen bonding dynamics rule, the first excited‐state hydrogen bonding change has been discussed without optimizing the excited‐state geometry conformations. According to the distinct difference between GT and GG (TT), we concluded that two gauche‐1PA monomers of one dimer are transformed at the same time to two trans‐1PA monomers.     

Some exact solutions to the inhomogeneous higher-order nonlinear Schrodinger equation by a direct method

By symbolic computation and a direct method, this paper presents some exact analytical solutions of the one-dimensional generalized inhomogeneous higher-order nonlinear Schrodinger equation with variable coefficients, which include bright solitons, dark solitons, combined solitary wave solutions, dromions, dispersion-managed solitons, etc. The abundant structure of these solutions are shown by some interesting figures with computer simulation.     

Existence Results for Impulsive Neutral Stochastic Functional Integro-Differential Equations with Infinite Delays

In this paper, we prove the existence of mild solutions for a class of impulsive neutral stochastic functional integro-differential equations with infinite delays in an abstract space by means of the Krasnoselskii-Schaefer type fixed point theorem.     

Preliminary study on aerosol particle addition calibration method for on-line quantitative analysis of airborne radioactive particles with ICP-MS

An ambient aerosol concentration enrichment system coupled with ICP-MS for real-time monitoring of airborne radioactive particles is now under development. ICP-MS is very sensitive to sample introduction conditions, so it is necessary to develop an easy-use calibration method for on-line quantitative analysis in field application. In this paper, a calibration method using standard solution instead of monodisperse particles was established and validated preliminarily. First of all, four parameters for the method were determined experimentally, including: uptake flow rate and nebulisation efficiency of the Microconcentric nebuliser, nebulisation/transport efficiency of Aridus Desolvating Sample Introduction System, and Relative Sensitivity Factor between ¹⁵⁹?Tb and ¹⁷⁴?Yb. Then, monodisperse terbium nitrate particles were generated by a commercial Vibrating Orifice Aerosol Generator. Continuous aerosols of ytterbium nitrate droplets were nebulised from standard solution. They were mixed together, desolvated through the membrane dryer and introduced into ICP-MS for on-line analysis of terbium nitrate particles. The air sampled from nuclear environment was also introduced into ICP-MS to investigate the effect of flow rate on instrument responses. Finally, atom numbers of ¹⁵⁹?Tb in discrete terbium nitrate particles were determined using the calibration method and compared to the calculated value. Results show that when air flow rate increase from 10?mL?min^?1 to 100?mL?min^?1, the ratio of ¹⁵⁹?Tb ion count to ¹⁷⁴?Yb ion intensity keeps constant although instrument sensitivity decreases by a factor of 25. The relative standard deviation of ¹⁵⁹?Tb atom number measured is better than 18%. The discrepancy with the calculated value could be attributed to the over-estimation of atom number in the particles generated by VOAG because there was some liquid leakage in the VOAG.