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.     

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.     

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.     

Fingerprint analysis of Flos Lonicerae japonicae using binary HPLC profiling

Binary chromatographic profiling was employed in fingerprint analysis of Flos Lonicerae japonicae, the flower bud of Lonicera japonica Thunb. Standardized procedures were used to develop the profiling for both aqueous and ethanolic extracts. Other species in the previous Chinese Pharmacopoeia and some in folk remedy were successfully differentiated from L. japonica Thunb. by hierarchiral cluster analysis of the chromatographic profiles. Correlation analysis showed that six chromatographic peaks in ethanolic extract were positively correlated with in vitro bacteriostasis activity. Two standard fingerprints were developed with 10 genuine samples of L. japonica Thunb. Similarity analysis with a limited number of samples showed a fair consistence in the chromatographic profiling of L. japonica Thunb. from various sources and two harvests, and significant differences from other species. Combination use of the two fingerprints demonstrated confirmative identification and quality assessment of Flos Lonicerae japonicae.     

Stochastic lot-sizing problem with deterministic demands and Wagner-Whitin costs

In this paper, we consider a two-stage stochastic uncapacitated lot-sizing problem with deterministic demands and Wagner-Whitin costs. We develop an extended formulation in the higher dimensional space that provides integral solutions by showing that its constraint matrix is totally unimodular. We also provide the integral polyhedron of the problem in the original space by projecting the extended formulation to the original space.     

Synthesis of glycerol carbonate with high surface area ZrO2–KOH catalyst

High surface area ZrO₂–KOH sample was prepared and used the catalyst for the synthesis of glycerol carbonate (GC) from dimethyl carbonate (DMC) and glycerol. The structure properties of ZrO₂–KOH were characterized by XRD, BET, CO₂-TPD, XPS, and ICP-OES. It was found that the strong basicity of ZrO₂–KOH might be attributed to the oxygen vacancies as well as the big surface area. Experiments were developed to evaluate the effects of catalysis loading, proportion of reactants, temperature and reaction time on the conversion of glycerol to GC. The consequences showed that ZrO₂–KOH was a highly efficient basic catalyst for synthesis of GC from glycerol. The catalytic performance of ZrO₂–KOH is much better than that of ZrO₂–KOH–CP, ZrO₂–NH₄OH, and some reported heterogeneous catalysts. And the higher performance of ZrO₂–KOH was ascribed to the strong basicity. 99.43% conversion was obtained in a particular situation of catalyst/glycerol weight ratio of 3 wt%, DMC/glycerol molar ratio of 3:1, reaction temperature of 80 °C, and reaction time of 2 h. The plausible reaction mechanism for the transesterification on the strong basic active sites was discussed.

     

LPA-MNI: An Improved Label Propagation Algorithm Based on Modularity and Node Importance for Community Detection

Community detection is of great significance in understanding the structure of the network. Label propagation algorithm (LPA) is a classical and effective method, but it has the problems of randomness and instability. An improved label propagation algorithm named LPA-MNI is proposed in this study by combining the modularity function and node importance with the original LPA. LPA-MNI first identify the initial communities according to the value of modularity. Subsequently, the label propagation is used to cluster the remaining nodes that have not been assigned to initial communities. Meanwhile, node importance is used to improve the node order of label updating and the mechanism of label selecting when multiple labels are contained by the maximum number of nodes. Extensive experiments are performed on twelve real-world networks and eight groups of synthetic networks, and the results show that LPA-MNI has better accuracy, higher modularity, and more reasonable community numbers when compared with other six algorithms. In addition, LPA-MNI is shown to be more robust than the traditional LPA algorithm.     

海岸碎波拍的计算

研究了一维碎波拍的计算方法．波浪控制方程由欧拉方程在短波周期上平均而得到．为了考虑低频波浪在海岸上的破碎，采用了ＷＡＦ（ＷｅｉｇｈｔｅｄＡｖｅｒａｇｅＦｌｕｘ）方法求解长波方程．对由辐射应力和海底摩擦力引起的方程非齐次项采用了时间算子分裂法进行了处理，并对由此产生的误差进行了修正．计算了单色波和双色波垂直入射海岸的情况，并与实验结果进行了对比．