The local ultraconvergence of high‐order finite element method for second‐order elliptic problems with constant coefficients over a rectangular partition

In this article, we will discuss the local ultraconvergence of high‐degree finite element method based on a rectangular partition for the second‐degree elliptic problem with constant coefficients in Ω ? ?² , u( y ) = 0 on ?Ω . Based on suitable regularity, ultraconvergence of the displacement of the extrapolated kth (k ≥ 3) degree finite element solution has been obtained by an extrapolation technique. Finally, numerical experiments are applied to demonstrate our theoretical findings.     

Comparative pharmacokinetic study of four major bioactive components after oral administration of Zhi‐Zi‐Hou‐Po decoction in normal and corticosterone‐induced depressive rats

A highly selective and efficient LC–MS/MS method was developed to determine the plasma concentration of magnolol, hesperidin, neohesperidin and geniposide following oral administration of Zhi‐Zi‐Hou‐Po decoction in normal and depressed rats. Plasma samples were pretreated by protein precipitation with methanol. Chromatographic separation was performed on an XTerra^® MS C₁₈ column using a gradient elution with a mobile phase composed of acetonitrile–0.1% aqueous formic acid. The proposed method was validated to be specific, accurate and precise for the analytes determination in plasma samples. The calibration curves displayed good linearity over definite concentration ranges for the analytes. The intra‐ and inter‐day precision of the proposed method at three different levels were all within <11.13% and the relative errors ranged from ?8.46 to 8.93%. The recovery of the four compounds ranged from 82.72 to 89.08% and no apparent matrix effect was observed during sample analysis. After full validation, the established method was successfully applied for comparing the pharmacokinetics of four components between normal and depressed rats. The results showed that the AUC and C_max of four analytes in depressed rats were significantly different from those in normal rats and might provide helpful information to guide the clinical use of Zhi‐Zi‐Hou‐Po to treat depression.     

时间延迟扩散-波动分数阶微分方程有限差分方法

本文提出求解时间延迟扩散-波动分数阶微分方程有限差分方法，方程中对时间的一阶导函数用α阶（0 < α < 1） Caputo分数阶导数代替.文章中利用Lubich线性多步法对分数阶微分进行差分离散，且文章利用分段区间证明该方法是稳定的，且利用数值实验加以验证.     

Investigation of the interaction between protein and europium doped polymer

The interactions between bovine serum albumin (BSA) and polymer (poly (METAC-co-NIPAm-co-Eu(AA)3Phen), PMNEu) containing rare earth element (Europium) were detailedly investigated by both of experimental techniques, such as fluorescence spectroscopic analysis, zeta-potential characterization, hydrodynamic size measurements and transmission electron microscopy (TEM) observation, and theoretical calculations. As a result, we concluded that PMNEu could interact with BSA through electrostatic force and quench the fluorescence of BSA, which was regarded as the static quenching mechanism. In addition, the binding constant and binding sites number of BSA with PMNEu were calculated, and the distance between PMNEu and BSA was also estimated to be 1.9?nm based on Föster’s theory. Furthermore, the two fluorescence peaks of PMNEu at 594?nm and 618?nm were detected, and the density of them increased with the more BSA being added to couple with PMNEu. Additionally, The zeta-potential results confirmed the electrostatic interaction mode between BSA and PMNEu, which was concluded with the previous thermodynamic analysis. At last, the results from the hydrodynamic size measurement had a good agreement with those from the TEM observation about the structure and size variation during the complexation of PMNEu with different concentrations of BSA.     

Pharmacokinetic analysis of plasma bicyclol by liquid chromatography–tandem mass spectrometry

Bicyclol is a synthetic drug widely used to treat chronic hepatitis B. This study aimed to develop a selective, sensitive and high‐throughput liquid chromatography–tandem mass spectrometric method for the detection of bicyclol in human plasma. Bicyclol was detected using a multiple reaction monitoring mode, with ammonium adduct ions (m/z 408.2) as the precursor ion and the [M‐CH₃]⁺ ion (m/z 373.1) subjected to demethylation as the product ion. Chromatographic separation was achieved using a Zobax Eclipse XDB‐C₁₈ column with a gradient elution and a mobile phase of 2 mm ammonium formate and acetonitrile. Bicyclol was extracted from plasma matrix by precipitation. A linear detection response was obtained for bicyclol ranging from 0.500 to 240 ng/mL, and the lower limit of quantification was 0.500 ng/mL. The intra‐ and inter‐day precisions were all ≤7.4%, and the accuracies were within ±6.0%. The extraction recovery was >95.9%, and the matrix effects were between 96.0% and 108%. Bicyclol was found to be unstable in human plasma at room temperature, but the degradation was minimized by conducting sample collection and preparation in an ice bath. The validated method was successfully applied to investigate the pharmacokinetics of bicyclol tablets in six healthy Chinese volunteers.     

Rapid quantitative analysis of etoricoxib in human plasma by UPLC‐MS/MS and application to a pharmacokinetic study in Chinese healthy volunteers

A selective and sensitive liquid chromatography–tandem mass spectrometry method was developed for simultaneous determination of etoricoxib in human plasma. Chromatography was performed on an Acquity UPLC HSS T3 column (1.8 μm, 50 × 2.1 mm), with a flow rate of 0.600 mL/min, using a gradient elution with acetonitrile and water which contained 2 mm ammonium acetate as the mobile phase. Detection was carried out on Triple QuadTM 5500 mass spectrometer under positive‐ion multiple reaction monitoring mode. The respective mass transitions used for quantification of etoricoxib and etoricoxib‐d3 were m/z 359.0 → 280.1 and m/z 362.0 → 280.2. Calibration curves were linear over the concentration range of 5–5000 ng/mL. The validated method was applied in the pharmacokinetic study of etoricoxib in Chinese healthy volunteers under fed and fasted conditions. After a single oral dose of 120 mg, the main pharmacokinetic parameters of etoricoxib in fasted and fed groups were respectively as follows: peak concentration, 2364.78 ± 538.01 and 1874.55 ± 367.90 ng/mL; area under the concentration–time curve from 0 to 120 h, 44,605.53 ± 15,266.66 and 43,516.33 ± 12,425.91 ng h/mL; time to peak concentration, 2.00 and 2.50 h; and half‐life, 24.08 ± 10.06 and 23.64± 6.72 h. High‐fat food significantly reduced the peak concentration of etoricoxib (p = 0.001) but had no effect on the area under the concentration–time curve.     

Effect of quality control on the proliferation of the extract from Taraxacum mongolicum Hand.‐Mazz. in Lactobacillus plantarum

In recent years, the fingerprint of high‐performance liquid chromatography has been extensively applied in the identification and quality control of traditional Chinese medicine. It can be a potential protocol for assessing the authenticity, stability and consistency of traditional Chinese medicine and guaranteeing the expected biological activity. In this paper, a method using high‐performance liquid chromatography to identify and control the quality of the extract of Taraxacum mongolicum Hand.‐Mazz. (TME) was established. With this method, the correlation coefficients of the similarity of 10 batches were ≥0.994. The TME displayed a steady proliferative effect in Lactobacillus plantarum. In brief, this study successfully built a reliable, simple and efficient method to control and confirm the quality and the stability of biological activity of the TME.     

AgAlSe2晶体高压相变的第一性原理研究

基于密度泛函理论,采用广义梯度近似法,研究了黄铜矿结构AgAlSe₂在高压下的晶体结构、晶格动力学稳定性与电子结构.结果显示:在0 GPa时AgAlSe₂的晶格参数与实验值吻合,在13.9 GPa附近,质量密度、Se-Ag键长、Se-Al键长、晶格常数a突然增大,相对晶胞体积V/V₀、晶格常数c突然减小,声子谱出现虚频,结构变得不稳定,带隙发生突变,数值呈减小趋势.表明AgAlSe₂晶体在13.9 GPa附近发生结构相变.该研究为AgAlSe₂晶体在理论上所能承受的高压提供信息支撑.     

Stable Heterometallic Cluster‐Based Organic Framework Catalysts for Artificial Photosynthesis

A series of stable heterometallic Fe₂M cluster‐based MOFs ( NNU‐31‐M , M=Co, Ni, Zn) photocatalysts are presented. They can achieve the overall conversion of CO₂ and H₂O into HCOOH and O₂ without the assistance of additional sacrificial agent and photosensitizer. The heterometallic cluster units and photosensitive ligands excited by visible light generate separated electrons and holes. Then, low‐valent metal M accepts electrons to reduce CO₂, and high‐valent Fe uses holes to oxidize H₂O. This is the first MOF photocatalyst system to finish artificial photosynthetic full reaction. It is noted that NNU‐31‐Zn exhibits the highest HCOOH yield of 26.3 μmol g^?1 h^?1 (selectivity of ca. 100 %). Furthermore, the DFT calculations based on crystal structures demonstrate the photocatalytic reaction mechanism. This work proposes a new strategy for how to design crystalline photocatalyst to realize artificial photosynthetic overall reaction.