Quantitative Radar REMPI measurements of methyl radicals in flames at atmospheric pressure

Spatially resolved quantitative measurements of methyl radicals (CH₃) in CH₄/air flames at atmospheric pressure have been achieved using coherent microwave Rayleigh scattering from Resonance enhanced multi-photon ionization, Radar REMPI. Relative direct measurements of the methyl radicals were conducted by Radar REMPI via the two-photon resonance of the $ 3p^{2} A_{2}^{\prime \prime } 0_{0}^{0} $ state and subsequent one-photon ionization. Due to the proximity of the argon resonance state of 2s ²2p ⁵4f [7/2, J = 4](4+1 REMPI by 332.5 nm) with the CH₃ state of $ 3p^{2} A_{2}^{\prime \prime } 0_{0}^{0} $ (2+1 REMPI by 333.6 nm), in situ calibration with argon was performed to quantify the absolute concentration of CH₃. The REMPI cross sections of CH₃ and argon were calculated based on time-dependent quantum perturbation theory. The measured CH₃ concentration in CH₄/air flames was in good agreement with numerical simulations performed using detailed chemical kinetics. The Radar REMPI method has shown great flexibility for spatial scanning, large signal-to-noise ratio for measurements at atmospheric pressures, and significant potential to be straightforwardly generalized for the quantitative measurements of other radicals and intermediate species in practical and relevant combustion environments.     

Poly(cyclotriphosphazene-co-phloroglucinol)PCPP as a solid phase extractant for preconcentrative separation of uranium(VI) from aqueous solution

Poly(cyclotriphosphazene-co-phloroglucinol) (PCPP) microspheres, a new solid phase extraction for extracting uranium(VI), synthesized via one-pot precipitation copolymerization. The PCPP microspheres were characterized by FT-IR, SEM/EDS, zeta potential and N₂ adsorption/desorption isotherms. Through the extraction experiment to evaluate the extraction behavior of the PCPP microspheres for uranium(VI). The extractant can achieve the optimal effect under the conditions of contact time with 60 min, pH = 3.5, initial concentration 100 mg L⁻¹ and extractant dosage 0.70 g L⁻¹. The extraction behavior obeyed with the pseudo second-order model and Langmuir isotherm model.

     

An ultraperformance liquid chromatography–tandem mass spectrometry method for determination of anastrozole in human plasma and its application to a pharmacokinetic study

A fast, selective and sensitive ultraperformance liquid chromatography–tandem mass spectrometry method was developed for determination and pharmacokinetic study of anastrozole in human plasma. Plasma sample pretreatment involved a one‐step extraction with diethyl ether of 500 µL plasma. The chromatographic separation was carried out on an Acquity UPLC^TM BEH C₁₈ column with a mobile phase consisting of methanol–10 mmol/L ammonium acetate (75:25, v/v) at a flow rate of 0.30 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring via electrospray ionization source with positive mode. A high throughput was achieved with a run time of 1.5 min per sample. The standard curve for anastrozole was linear (r² ≥ 0.99) over the concentration range of 0.0550–27.5 ng/mL with a lower limit of quantification of 0.0550 ng/mL. The intra‐ and inter‐day precision (relative standard deviation) values were not higher than 14% and the accuracy (relative error) was within ±3.2% at three quality control levels. This simple, fast and highly sensitive method was fully validated and successfully applied to a clinical pharmacokinetic study of anastrozole in healthy volunteers after oral administration. Copyright © 2010 John Wiley & Sons, Ltd.     

Development and validation of a hydrophilic interaction ultra‐high‐performance liquid chromatography–tandem mass spectrometry method for rapid simultaneous determination of 19 free amino acids in rat plasma and urine

Determination of amino acids in biofluids is a challenging task because of difficulties deriving from their high polarity and matrix interference. A simple, reliable and high‐throughput hydrophilic interaction UHPLC–MS/MS method was developed and validated for the rapid simultaneous determination of 19 free amino acids in rat plasma and urine samples in this paper. Hydrophilic method with a Waters Acquity UPLC BEH Amide column (100 × 2.1 mm,1.7 μm) was used with a gradient mobile phase system of acetonitrile and water both containing 0.2% formic acid. The analysis was performed on a positive electrospray ionization mass spectrometer via multiple reaction monitoring. Samples of 10 μL plasma and 50 μL urine were spiked with three deuterated internal standards, pretreated with 250 μL acetonitrile for one‐step protein precipitation and a final dilution of urine samples. Good linearities (r > 0.99) were obtained for all of the analytes with the lower limit of quantification from 0.1 to 1.2 μg/mL. The relative standard deviation of the intra‐day and inter‐day precisions were within 15.0% and the accuracy ranged from ?12.8 to 12.7%. The hydrophilic interaction UHPLC–MS/MS method was rapid, accurate and high‐throughput and exhibited better chromatography behaviors than the regular RPLC methods. It was further successfully applied to detect 19 free amino acids in biological matrix.     

Design,Synthesis and Activities of Aziridine Derivatives of N5-Methyltetrahydrofolate Against Methionine Synthase

Aziridine derivatives of N⁵-methyltetrahydrofolate were designed and synthesized based on the mechanism of methionine synthase, and their biological activities were investigated as well. The aziridine derivatives 1 and 6 exhibited superior inhibitory activities(IC₅₀: 5.05 and 4.15 μmol/L, respectively) compared to the corresponding chain analogue 4(IC₅₀=24.42 μmol/L). The results suggest that the aziridine derivatives can get potential activities against nucleophilic methionine synthase.     

A solution for cyclic scheduling of multi-hoists without overlapping

In this paper, we study the cyclic scheduling problem for electroplating lines where products are loaded into the system at one end and unloaded at the other end. The electroplating jobs must be processed within a given time window in each tank. There is no buffer between tanks. Two hoists sharing a common track are used to move products between the tanks in the production line. The objective is to minimize the production cycle time through scheduling hoist moves. A solution procedure is proposed in this study. The production line is first divided into two non-overlapping zones with a hoist assigned to each zone. Then a mixed integer linear programming model is developed for scheduling hoist moves. Computational results on a benchmark example problem are given in the paper to demonstrate the application of the proposed method.     

吡啶吡唑基配体C8-BPP对硝酸溶液中Am3+和Eu3+的萃取

合成了吡啶吡唑基配体C8-BPP[2,6-bis（5-（n-octyl）-1H-pyrazol-3-yl）pyridine],并采用红外光谱、核磁共振波谱、质谱等手段对其进行了表征.以正十二烷为稀释剂,2-溴己酸为协萃剂,研究了C8-BPP从HNO₃溶液中萃取Am³⁺和Eu³⁺的行为.重点考察了萃取时间、酸度和萃取剂浓度等对分配比D和分离因子SF_Am/Eu的影响.在HNO₃浓度为0.2~1.0 mol/L时,C8-BPP萃取Am³⁺和Eu³⁺的D值随HNO₃浓度增加而减小,SF_Am/Eu值先增大后减小;HNO₃浓度为0.5 mol/L时,SF_Am/Eu达到55.随着配体浓度的增加,C8-BPP萃取Am³⁺和Eu³⁺的D值均增加,SF_Am/Eu值缓慢减小,但仍在40以上.斜率分析表明,C8-BPP萃取Am³⁺和Eu³⁺均形成了1： 1型的萃合物.还采用紫外滴定、高分辨质谱、红外光谱、拉曼光谱和时间分辨荧光光谱等方法研究了C8-BPP与Eu³⁺的配位化学行为,并得到了配合物的组成和稳定常数.     

具有精确色散性的非线性波浪数学模型

以完全非线性的自由表面边界条件为基础,以波面升高\eta和自由表面速度势\phi _\eta为待求变量,建立了新的波浪方程．方程在色散性上是完全精确的,非线性近似至三阶．与缓坡方程相比较,两者都具有精确的色散性,但该方程属于非线性模型,可模拟波浪的非线性效应,且适用于不规则波．方程的特点是属于微分-积分方程,对如何处理方程中积分项进行了讨论,并数值模拟了不同周期的线性波和二阶Stokes波,也模拟了波群的非线性演化,以对模型进行验证．