Advantages of using a modified orthogonal sampling configuration originally designed for LC-ESI-MS to couple CE and MS for the determination of antioxidant phenolic compounds found in virgin olive oil

A ThermoFinnigan sheath liquid flow capillary electrophoresis-mass spectrometry system designed for coupling via a co-axial interface was coupled through an adapted via an alternative, commercially available interface for orthogonal sampling. The affordable, reversible structural alterations made in the commercial LC-MS interface resulted in improved analytical performance.The results of a conventional capillary electrophoresis (CE) method using a commercial co-axial source to determine antioxidant phenolic acids present in virgin olive oil, were compared with those obtained by using a modified orthogonal sampling position. In both cases, separations were done using a 10 mM ammonium acetate/ammonium hydroxide buffer solution at pH 10.0 and a constant applied voltage of 25 kV. The operating variables for the mass spectrometry interface were re-optimized for the modified orthogonal orientation. This allowed the sheath liquid, sheath gas flow rates and capillary voltage to be lowered with respect to the co-axial coupling configuration. In addition, the orthogonal sampling position provided a higher selectivity by effect of ion sampling excluding larger droplets—with an increased momentum along the axis—which were drained through the sink at the bottom of the ion source. Also, the new configuration facilitated sample ionization, improved electrospray stability and led to stronger signals as a result.The new system was validated in terms of precision (repeatability), linearity, and limits of detection and quantification. A comparison of the validation data with the results previously obtained by using a commercial co-axial configuration revealed the adapted orthogonal sampling position to provide better repeatability in both migration times and relative peak areas (<1% and 7% respectively with n = 15 replicates), a good linear range (with levels in the microgram-per-litre region) and lower limits of detection—especially for the compounds detected with the lowest sensitivity when co-axial ESI was used, as HFA, GEN, FER and VAN finding LOD among 24-3.0 μg L⁻¹ respectively.     

~(12)CO_2/~(13)CO_2体系中碳同位素的显微激光拉曼光谱研究

采用自行设计的装置制备了一系列不同比例的12CO2/13 CO2混合物,对混合物样品进行显微激光拉曼测试,获得CO2气体碳同位素分子的拉曼特征峰。对实验数据分析发现,12CO2的摩尔分数[x(12CO2)]与12CO2/13 CO2混合物中拉曼特征峰峰面积比之间存在数学关系式。根据拟合的关系式,利用显微激光拉曼光谱可以预测CO2气体碳同位素的组成,并为以后预测单个流体包裹体中12CO2的摩尔分数奠定了理论基础。     

Solvation of amino acid residues in water and urea-water mixtures: Volumes and heat capacities of 20 amino acids in water and in 8 molar urea at 25°C

The limiting partial molar volumes V ^o and heat capacities C _p ^o of 20 amino acids have been determined in water and in 8 molar urea at 25.0°C using flow calorimetry and flow densimetry. The side chain contributions to V ^o and C _p ^o were obtained as the difference between the properties of the various amino acids and those of glycine, both in water and in 8M urea. The solvent accessible surface area of the amino acid residues were obtained using a method developed by Hermann, and the total surface areas were separated into their hydrophobic A _Hb and hydrophilic components. In water, C _p ^o values for the various residues C _p ^o (R) were found well correlated with A _Hb , though much less so in the urea solution. Hence, C _p ^o (R) values, in water yield a good estimate of side chain hydrophobicity, but the (waterurea) transfer heat capacities appear strongly affected by specific solvation effects in the urea solution.Presented at the sixth Italian meeting on Calorimetry and Thermal Analysis (AICAT) held in Naples, December 4–7, 1984.     

Generalized area operators on L^p（R^n）

We introduce the generalized area operators by using nonnegative measures defined on upper half-spaces R＋^n＋1. The characterization of the boundedness and compactness of the generalized area operator from LP（]Rn） to Lq（IRn） is investigated in terms of s-Carleson measures with 1 〈 p, q 〈 ＋∞. In the case of p = q = 1, the weak type estimate is also obtained.     

Grandes deviations des diffusions sur les espaces de besov-orlicz et application

Dans cet article nous demontrons le principe de grandes déviations de Freidlin et Wentzeii pour les diffusions suivant la topologie de l'espace de Besov-Orlicz. Nous étendons ainsi le résultat de Ben Arous et Ledoux [3] concernant le cas höldérien et celui de Roynetie [16] tiaitant le cas du mouvement brownien en norrne de Besov Comme application on établit la loi fonctionnelle du Logarithme itéré de Strassen pour l'aire de Lévy en norme de Besov-Orlicz. Cette loi est plus fine que celle obtenue par N'zi et Eddahbi [14] avec la norme Hölderienne

In this paper, we prove a Freidlin-Wentzell large deviations principle in Besov-Orlicz space for diffusion processes. Our result is an extension of that of Ben-Arous and Ledoux [3] who have treated the Hölder norm case and that of Roynette [16] who have considered Brownian motion in Besov space. As an application, we establish a Strassen's law of the iterated logarithm for Lévy's area process. This law is more sharper than the one in Hölder norm obtained by N'zi and Eddahbi [14]     

从圆内接三角形面积想到的

首先证明了正三角形的外接椭圆中面积最小的是一个圆.进而用初等方法证明了二维情形的F.John定理.     

Bootstrap for estimating the MSE of the Spatial EBLUP

This work assumes that the small area quantities of interest follow a Fay–Herriot model with spatially correlated random area effects. Under this model, parametric and nonparametric bootstrap procedures are proposed for estimating the mean squared error of the empirical best linear unbiased predictor (EBLUP). A simulation study based on the Italian Agriculture Census 2000 compares bootstrap and analytical estimates of the MSE and studies their robustness to non-normality. Results indicate lower bias for the non-parametric bootstrap under specific departures from normality.      

Commutators of Littlewood-Paley Operators on Herz Spaces with Variable Exponent

Let ? ∈ L~2(S~(n-1)) be homogeneous function of degree zero and b be BMO functions. In this paper, we obtain some boundedness of the Littlewood-Paley Operators and their higher-order commutators on Herz spaces with variable exponent.     

Analysis of ray tube area in geometrical shock dynamics

We provide a rigorous analysis of structure of a ray tube in geometrical shock dynamics. Our aim is to shed more lights on the cross-sectional area function of a ray tube. We have shown that for a given ray tube and a given initial value of cross-sectional area, then its cross-sectional area can be determined uniquely everywhere. We give a definition of cross-sectional area of a ray tube in precise mathematical terms and from that we derive a set of relations, each describing the cross-sectional area for an arbitrary ray tube in geometrical shock dynamics. We have shown that from our results one can deduce Whitham’s area function relation as a partial differential equation from our general formulations. Some applications are discussed.