Screening of glycoside isomers in P. scrophulariiflora using ionic liquid‐based ultrasonic‐assisted extraction and ultra‐performance liquid chromatography/electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

A powerful ionic liquid‐based ultrasonic‐assisted extraction (ILUAE) method combined with ultra‐performance liquid chromatography coupled to electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (UPLC/ESI‐QTOFMSⁿ) was employed in the rapid simultaneous screening of iridoid glycosides, phenylethanoid glycosides, and cucurbitacin glycosides from P. scrophulariiflora. The ILUAE procedure was optimized over several ultrasonic parameters, including the ultrasonic power, concentration of the ionic liquid, and solid–liquid ratio. A comparison with conventional heat‐reflux extraction and regular UAE demonstrated that the optimized approach yielded a high extraction efficiency (Picroside I, 2.84%; Picroside II, 3.57%; 6‐O‐E‐feruloyl catalpol, 2.20%) within a short extraction time of 30 min. Negative ion mode ESI‐QTOFMS² analysis of the fragmentation reactions of the [M–H]^– ions was conducted to characterize the diagnostic ions related to the glycosyl moieties, aglycone units, and the type and substituted position of the ester groups. Interestingly, the positional isomers of the iridoid glycosides could be easily discriminated based on the characteristic ions. A total of 15 glycosides, including three groups of iridoid glycoside isomers and two groups of phenylethanoid glycoside isomers, were conveniently identified within 13.5 min. Moreover, 6'‐O‐vanilloyl catalpol was identified in P. scrophulariiflora for the first time. The method developed here was further validated by measuring the recovery, correlation coefficient (R²), and reproducibility (RSD, n = 5) of three iridoid glycosides: 89.60%–109.02%, 0.9991–0.9998, and 0.93%–1.44%, respectively. This study demonstrated the capabilities of ILUAE combined with UPLC/ESI‐QTOFMSⁿ for the rapid screening of glycosides in P. scrophulariiflora. This method offers an approach to similar studies on other natural plants. Copyright © 2012 John Wiley & Sons, Ltd.     

Investigation of capacitance storage and cyclic voltammetry for the electrochemical oxidation of phenol on iridium and lead oxide electrodes

Journal of Solid State Electrochemistry - The capacitance storage and cyclic voltammetry (CV) of electrochemical oxidation of phenol were investigated using IrO2–Ta2O5/Ti and β-PbO2/Ti...     

On the kačanov method for a quasi-newtonian flow problem 1

The Ka?anov method is an iteration method for solving nonlinear Problems. In this paper, we apply the Ka?anov method to solve the problem of quasi-Newtonian flow obeying the Carreau law. The emphasis of the paper is the derivation of a posteriori error estimate for Ka?anov iterates. A numerical example shows the efficiency of the error estimate.     

Synthesis and Structure Determination of SCM-15: A 3D Large Pore Zeolite with Interconnected Straight 12×12×10-Ring Channels

A new germanosilicate zeolite named SCM-15 (Sinopec Composite Material No. 15), the first zeolite containing a 3-dimensional (3D) channel system with interconnected 12-, 12-, and 10-ring channels (pore sizes: 6.1×7.2, 6.1×7.4, and 5.2×5.9 Å), has been synthesized using neutral 4-pyrrolidinopyridine as organic structure-directing agents (OSDAs). Its structure has been determined by combining single-crystal electron diffraction (SCED) and synchrotron powder X-ray diffraction (SPXD) data. The unique open framework structure of SCM-15 is related to that of FOS-5 ( BEC ), ITQ-7 ( ISV ), PKU-16 ( POS ), ITQ-26 ( IWS ), ITQ-21, Beta polymorph B, and SU-78B, since all these framework structures can be constructed from similar chains which are connected through shared 4-ring or double 4-ring (d4r) units. Based on this relation, six topologically reasonable 3D large or extra-large pore hypothetical zeolites are predicted.     

Nucleophilic Aromatic Substitution of Unactivated Aryl Fluorides with Primary Aliphatic Amines by Organic Photoredox Catalysis

In this work, a mild and transition-metal-free approach for the nucleophilic aromatic substitution (S_NAr) of unactivated fluoroarenes with primary aliphatic amines to form aromatic amines is reported. This reaction is facilitated by the formation of cationic fluoroarene radical intermediates in the presence of an acridinium-based organic photocatalyst under blue-light irradiation. Various electron-rich and electron-neutral fluoroarenes are competent electrophiles for this transformation. A wide range of primary aliphatic amines, including amino acid esters, dipeptides, and linear and branched amines are suitable nucleophiles. The synthetic utility of this protocol is demonstrated by the late-stage functionalization of several complex drug molecules.     

Dependence of dielectric,ferroelectric, and piezoelectric properties on crystalline properties of p(VDF‐co‐TrFE) copolymers

Thermal processing at various temperatures has been used to fabricate poly(vinylidene fluoride‐co‐trifluoroethylene) [P(VDF‐co‐TrFE)] films with varied crystalline properties in an attempt to improve their piezoelectric properties. Although the dielectric constant of the films annealed at higher temperature is smaller than that of cooled and quenched ones, it has been shown that the annealed films possess larger crystallinity and stacked lamellar crystal grain size. The ferroelectric domains deriving from crystal region in all the samples are effectively improved by hot polarization. As a result, the remnant polarizations (P_r) and coercive electric field (E_c) of the corresponding films are improved at a low frequency due to the response of dipoles in crystal phase, and the largest piezoelectric constant in the longitudinal thickness mode (d₃₃=?25 pC/N) is obtained in an annealed copolymer film. The results illustrate improving the crystal structure of P(VDF‐co‐TrFE) is an effective way to realize high electromechanical properties, which provides broadly applied scenery for this kind of copolymer in piezoelectric components. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

低钾血症对颅脑创伤患者预后的影响

目的 探讨低钾血症在颅脑创伤患者中的发病情况及其与预后的关系。方法 2010 年6月至2013 年6 月共有168 例住院期间出现低钾血症且年龄≥18 岁的颅脑创伤患者纳入研究。依据低钾血症严重程度的不同,将患者分成轻度组（3.00mmol/L≤血钾＜3.50mmol/L）、中度组（2.50mmol/L≤血钾＜3.00mmol/L）和重度组（血钾＜2.50mmol/L）,各组均采用患者血钾的最低值进行数据分析。高钠血症和低磷血症分别被定义为血钠＞147.00mmol/L 和血磷＜0.80mmol/L。结果 受试患者的血钾在1.10~3.40mmol/L,平均2.90mmol/L。当血钾出现最低值时,与其余两组比较,重度组患者具有更高的血钠和更低的血磷水平（均P＜0.01）。与轻度组（10.5%）或中度组（25.7%）相比,重度组患者的病死率（82.1%）显著上升（均P＜0.01）。多变量逻辑回归分析结果显示,低格拉斯哥昏迷评分（OR=1.28,95%CI=1.12~1.42,P＜0.01）、低血钾（OR=5.57,95%CI=2.76~10.93,P＜0.01）、低血磷（OR=2.76,95%CI=1.11~7.25,P＜0.01）以及高血尿素氮（OR=1.16,95%CI=1.07~1.24,P＜0.01）是导致患者死亡的独立危险因素。结论 颅脑创伤患者是出现低钾血症的高危人群,重度低钾血症的患者更容易合并高钠血症和低磷血症。重度低钾血症和低磷血症是颅脑创伤患者死亡的独立危险因素。