Evaluation of measurement uncertainty in EA–IRMS: for determination of δ 13C value and C-4 plant sugar content in adulterated honey

In this study, the method for determining the stable carbon isotope ratio value was validated. Measurement uncertainty of stable carbon isotope ratio value of whole honey and its extracted protein derived from repeatability, reference gas, reference standards and calibration curve was calculated by applying the “bottom-up” approach according to Eurachem/CITAC guide. The expanded uncertainties for all results ranged from 0.14 to 0.19 ‰, with most of them between 0.15 and 0.16 ‰ (the coverage factor k = 2, the level of confidence p is approximately 95 %). The percentage contribution of each source to the relative combined uncertainty was calculated. The data indicated that calibration curves have more contribution to the relative combined uncertainty than repeatability and reference standards. On the other hand, the measurement uncertainty of C-4 sugar content in honey was estimated. Based on these results, 58 honey samples, such as acacia, chaste, Northeast China black bee, flowers and jujube honey, have been gathered to determine the C-4 plant sugar content adulteration in honey by elemental analyzer with an isotope ratio mass spectrometer. It can be found that all honey samples were not adulterated by C-4 plant sugar.     

聚芳醚酮树脂的分子设计与合成及性能

聚芳醚酮树脂是20世纪发展起来的重要特种工程塑料.因其优良的耐热、耐腐蚀、耐摩擦及生物相容性好等特点,在国防军工、武器装备、航空航天、电子、汽车、机械、石油工业、核能及理疗卫生等高技术领有广泛的应用.此类材料大都采用双酚单体和双氟单体通过A2+B2型亲核缩聚反应制备.这类聚合物的分子结构对材料的性能影响较大,一般情况下分子链由醚、酮、苯三元规整结构构成时,聚合物为半结晶态;然而,当分子结构中存在侧基或其他非规整结构往往破坏聚合物的结晶结构,聚合物呈现无定型态.半结晶聚芳醚酮聚合物具有非常优异的耐热、耐化学稳定性一般作为结构型材料使用;无定型聚芳醚酮具有良好的加工性能,并且可进行一些功能化成为一类优异的功能型材料.本文从结构与性能关系出发,介绍了聚芳醚酮树脂种类,聚芳醚酮树脂的发展历程及合成方法;探讨了聚芳醚酮材料结构与性能关系;总结了功能性聚芳醚酮材料的前沿进展;最后结合实际展望了聚芳醚酮的应用发展方向.     

A green strategy for lithium isotopes separation by using mesoporous silica materials doped with ionic liquids and benzo-15-crown-5

Three new mesoporous silica materials IL15SGs (HF15SG, TF15SG and DF15SG) doped with benzo-15-crown-5 and imidazolium based ionic liquids (C₈mim⁺PF₆ ^?, C₈mim⁺BF₄ ^? or C₈mim⁺NTf ₂ ^? ) have been prepared by a simple approach to separating lithium isotopes. The formed mesoporous structures of silica gels have been confirmed by transmission electron microscopy image and N₂ gas adsorption–desorption isotherm. Imidazolium ionic liquids acted as templates to prepare mesoporous materials, additives to stabilize extractant within silica gel, and synergetic agents to separate the lithium isotopes. Factors such as lithium salt concentration, initial pH, counter anion of lithium salt, extraction time, and temperature on the lithium isotopes separation were examined. Under optimized conditions, the extraction efficiency of HF15SG, TF15SG and DF15SG were found to be 11.43, 10.59 and 13.07 %, respectively. The heavier isotope ⁷Li was concentrated in the solution phase while the lighter isotope ⁶Li was enriched in the gel phase. The solid–liquid extraction maximum single-stage isotopes separation factor of ⁶Li–⁷Li in the solid–liquid extraction was up to 1.046 ± 0.002. X-ray crystal structure analysis indicated that the lithium salt was extracted into the solid phase with crown ether forming [(Li_0.5)₂(B15)₂(H₂O)]⁺ complexes. IL15SGs were also easily regenerated by stripping with 20 mmol L^?1 HCl and reused in the consecutive removal of lithium ion in five cycles.     

Metabolism of synthetic cannabinoids PB-22 and its 5-fluoro analog, 5F-PB-22, by human hepatocyte incubation and high-resolution mass spectrometry

Background

PB-22 (1-pentyl-8-quinolinyl ester-1H-indole-3-carboxylic acid) and 5F-PB-22 (1-(5-fluoropentyl)-8-quinolinyl ester-1H-indole-3-carboxylic acid) are new synthetic cannabinoids with a quinoline substructure and the first marketed substances with an ester bond linkage. No human metabolism data are currently available, making it difficult to document PB-22 and 5F-PB-22 intake from urine analysis, and complicating assessment of the drugs’ pharmacodynamic and toxicological properties.

Methods

We incubated 10 μmol/l PB-22 and 5F-PB-22 with pooled cryopreserved human hepatocytes up to 3 h and analyzed samples on a TripleTOF 5600+ high-resolution mass spectrometer. Data were acquired via TOF scan, followed by information-dependent acquisition triggered product ion scans with mass defect filtering (MDF). The accurate mass full scan MS and MS/MS metabolite datasets were analyzed with multiple data processing techniques, including MDF, neutral loss and product ion filtering.

Results

The predominant metabolic pathway for PB-22 and 5F-PB-22 was ester hydrolysis yielding a wide variety of (5-fluoro)pentylindole-3-carboxylic acid metabolites. Twenty metabolites for PB-22 and 22 metabolites for 5F-PB-22 were identified, with the majority generated by oxidation with or without glucuronidation. For 5F-PB-22, oxidative defluorination occurred forming PB-22 metabolites. Both compounds underwent epoxide formation followed by internal hydrolysis and also produced a cysteine conjugate.

Conclusion

Human hepatic metabolic profiles were generated for PB-22 and 5F-PB-22. Pentylindole-3-carboxylic acid, hydroxypentyl-PB-22 and PB-22 pentanoic acid for PB-22, and 5′-fluoropentylindole-3-carboxylic acid, PB-22 pentanoic acid and the hydroxy-5F-PB-22 metabolite with oxidation at the quinoline system for 5F-PB-22 are likely the best targets to incorporate into analytical methods for urine to document PB-22 and 5F-PB-22 intake.

Validation of an LC-MS/MS method for the quantitative determination of a novel fungicide: pyraoxystrobin in rat plasma and its application to a toxicokinetics study

A simple, sensitive, and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for determination of pyraoxystrobin in rat plasma and applied to a toxicokinetics study. The separation was performed by gradient elution on a Luna 5 μ C18 (2) 100 Å column (50?×?4.6 mm I.D., 5 μm) with mobile phase: water (0.1 % formic acid, v/v)/acetonitrile (0.1 % formic acid, v/v), followed by quantification with a mass detector in multiple reaction monitoring (MRM) mode using ESI as an interface. The calibration curve was linear over a concentration range of 1.00–200 ng/mL. The recovery for pyraoxystrobin ranged from 101.4 to 108.2 %. The intraday bias and precision ranged from ?9.3 to 8.1 % and from 0.7 to 8.4 %, respectively, and the interday bias and precision ranged from ?0.3 to 4.0 % and from 4.4 to 7.2 %, respectively. The toxicokinetics of pyraoxystrobin after single 100 and 1,000 mg/kg oral doses were studied in rats. Figure

The chromatogram of pyraoxystrobin highest calibration standard (ULOQ) extract.     

GPCR A2A AR腺苷受体蛋白的激动剂结合及其诱导的蛋白活性开关构象变化

运用分子动力学模拟,研究了腺苷酸（激动剂）与A2AAR腺苷受体蛋白的相互作用和配体结合诱导的蛋白动力学变化．识别了与腺苷酸结合力强于0．5kcal／mol的关键基团：A63^2．61,I66^2．64,V84^3.32,L85^3.33,T88^3.36,F168^5.29,M177^5.38,L249^6.51,H250^6.52和N253^6.55,观察到腺苷酸没有与L167^5.28相互作用,这一结果支持了L167^5.28是抑制剂特异性结合位点,不与激动剂结合．未结合配体（激动剂或抑制剂）的单体A2AAR和腺苷酸结合后的A2AAR在构象上有三个不同功能性开关．腺苷酸结合可以诱导A2AAR腺苷受体蛋白的构象调整,使得三个功能性开关器件的构象与单体A2AAR不同．     

Energetic Salts Based on an Oxygen‐Containing Cation: 2,4‐Diamino‐1,3,5‐triazine‐6‐one

A family of energetic salts with high thermal stability and low impact sensitivity based on an oxygen‐containing cation, 2,4‐diamino‐1,3,5‐triazine‐6‐one, were synthesized and fully characterized by IR and multinuclear (¹H, ¹³C) NMR spectroscopy, elemental analysis, and differential scanning calorimetry. Insights into their sensitivities towards impact, friction, and electrostatics were gained by submitting the materials to standard tests. The structures of 2,4‐diamino‐1,3,5‐triazine‐6‐one nitrate, 2,4‐diamino‐1,3,5‐triazine‐6‐one sulfate, 2,4‐diamino‐1,3,5‐triazine‐6‐one perchlorate, 2,4‐diamino‐1,3,5‐triazine‐6‐one 5‐nitrotetrazolate were determined by single‐crystal X‐ray diffraction; their densities are 1.691, 1.776, 1.854, and 1.636 g cm^?3, respectively. Most of the salts decompose at temperatures over 180 °C; in particular, the salts 2,4‐diamino‐1,3,5‐triazine‐6‐one nitrate and 2,4‐diamino‐1,3,5‐triazine‐6‐one perchlorate, which decompose at 303.3 and 336.4 °C, respectively, are fairly stable. Furthermore, most of the salts exhibit excellent impact sensitivities (>40 J), friction sensitivities (>360 N), and are insensitive to electrostatics. The measured densities of these energetic salts range from 1.64 to 2.01 g cm^?3. The detonation pressure values calculated for these salts range from 14.6 to 29.2 GPa, and the detonation velocities range from 6536 to 8275 m s^?1; these values make the salts potential candidates for thermally stable and insensitive energetic materials.     

Raman spectroscopy measurement of levofloxacin lactate in blood using an optical fiber nano‐probe

Liquid chromatography and mass spectrometry were time‐consuming and expensive as the main methods for the drug analysis at present, and the samples must be pretreated. The Raman spectroscopy measurement methods were fast and simple, so the Raman spectroscopy methods for the drug analysis were explored in this paper. An optical fiber nano‐probe coated with gold nanoparticles was fabricated and used with surface‐enhanced Raman spectroscopy (SERS) to measure levofloxacin lactate. The resulting SERS spectra of levofloxacin lactate in mouse blood that was detected by the optical fiber nano‐probe clearly showed the characteristic wave numbers of levofloxacin lactate, indicating that optical fiber nano‐probes can be used with spectral techniques to analyze drugs in vitro or potentially even in vivo. Copyright © 2015 John Wiley & Sons, Ltd.     

The Comparative Study of Reaction Mechanisms and Catalytic Performances of Cu–SSZ-13 and Fe–SSZ-13 for the NH3-SCR Reaction

Catalysis Surveys from Asia - The catalytic performances and mechanism differences of model catalysts Cu–SSZ-13 and Fe–SSZ-13 with similar metal content and Si/Al ratio were compared....     

Sigma-1 Receptor Agonist TS-157 Improves Motor Functional Recovery by Promoting Neurite Outgrowth and pERK in Rats with Focal Cerebral Ischemia

Sigma-1 (σ-1) receptor agonists are considered as potential treatment for stroke. TS-157 is an alkoxyisoxazole-based σ-1 receptor agonist previously discovered in our group. The present study describes TS-157 profile in a battery of tests for cerebral ischemia. Initial evaluation demonstrated the compound’s safety profile and blood–brain barrier permeability, as well as its ability to induce neurite outgrowth in vitro. The neurite outgrowth was shown to be mediated via σ-1 receptor agonism and involves upregulation of ERK phosphorylation (pERK). In particular, TS-157 also significantly accelerated the recovery of motor function in rats with transient middle cerebral artery occlusion (tMCAO). Overall, the results herein support the notion that σ-1 receptor agonists are potential therapeutics for stroke and further animal efficacy studies are warranted.