Improvement of the Pd/Al2O3 Catalyst by the Control of the Sol-Gel Preparative Parameters

In this work, the metal dispersion of the Pd/Al₂O₃ catalyst prepared by sol-gel method is improved by an adequate optimisation of the preparative variables. First, the gelation temperature and the ageing time are selected, in order to avoid the reduction of the metal precursor (palladium acetylacetonate, Pd(acac)₂) by the solvent (sec-butanol, sB). The metal sintering effect on the catalysts treated in oxygen at 500°C is then minimized when the alumina pore size is controlled by the variation of the alumium alkoxide (AsB) concentration and the acetic acid amount ([AcA]/[AsB]). The appearance of new palladium particles on the alumina surface and the matching between the particle diameters and the pore sizes were also effective for the metallic surface area improvement on the samples treated in oxygen at 800°C. Compared to the reference catalysts, the higher metal dispersion obtained on the sol-gel ones was the determinant factor for their higher catalytic activity in methane combustion.     

An Arithmetic Reduction of Finite Rank 3 Geometries with Linear Spaces as Plane Residues and with Dual Linear Spaces as Point Residues

Let be a rank three incidence geometry of points, lines and planes whose planes are linear spaces and whose point residues are dual linear spaces (notice that we do not require anything on the line residues). We assume that the residual linear spaces of belong to a natural class of finite linear spaces, namely those linear spaces whose full automorphism group acts flag-transitively and whose orders are polynomial functions of some prime number. This class consists of six families of linear spaces. In the amalgamation of two such linear spaces imposes an equality on their orders leading, in particular, to a series of diophantine equations, the solutions of which provide a reduction theorem on the possible amalgams of linear spaces that can occur in .We prove that one of the following holds (up to a permutation of the words point and plane):A) the planes of and the dual of the point residues belong to the same family and have the same orders,B) the diagram of is in one of six families,C) the diagram of belongs to a list of seven sporadic cases.Finally, we consider the particular case where the line residues of are generalized digons.     

Intermolecular contact interactions and their temperature dependence

A model, based on inverse gas chromatography experiments, has been developed for intermolecular interaction and its temperature dependence. The model ascribes to each substance a four-component solubility parameter; the four components reflect the van der Waals, polar, electron donor, and electron acceptor interactive properties. Their values depend on temperature in the same manner as does the cohesive energy. The latter was found to depend only on the critical temperature, the acentric factor, and the reduced temperature. The model was used for evaluation of the solubility parameters from polymer-solvent interaction coefficients and their temperature dependence with high accuracy. For binary solventsolvent mixtures, the free energy of mixing and its temperature dependence, as well as enthalpy of mixing can be derived from this model with a good accuracy.     

Site-specific detection of S-nitrosylated PKB alpha/Akt1 from rat soleus muscle using CapLC-Q-TOF(micro) mass spectrometry

Protein Kinase Balpha(PKBalpha, or Akt1) is believed to play a crucial role in programmed cell death, cancer progression and the insulin-signaling cascade. The protein is activated by phosphorylation at multiple sites and subsequently phosphorylates and activates eNOS. Free cysteine residues of the protein may capture reactive, endogenously produced nitric oxide (NO) as S-nitrosothiols. Site-specific detection of S-nitrosylated cysteine residues, usually at low stoichiometry, has been a major challenge in proteomic research largely due to the lack of mass marker for S-nitrosothiols that are very labile under physiologic conditions. In this report we describe a sensitive and specific MS method for detection of S-nitrosothiols in PKB alpha/Akt1 in rat soleus muscle. PKB alpha/Akt1 was isolated by immunoprecipitation and 2D-gel electrophoresis, subjected to in-gel tryptic digestion, and cysteinyl nitrosothiols were reacted with iodoacetic acids [2-C(12)/C(13) = 50/50] under ascorbate reduction conditions. This resulted in the production of relatively stable carboxymethylcysteine (CMC) immonium ions (m/z 134.019 and m/z 135.019) within a narrow argon collision energy (CE = 30 +/- 5 V) in the high MS noise region. In addition, free and disulfide-linked cysteine residues were converted to carboxyamidomethylcysteines (CAM). Tryptic S-nitrosylated parent ion was detected with a mass accuracy of 50 mDa for the two CMC immonium ions at the triggered elution time during capillary liquid chromatography (LC) separation. A peptide containing Cys(296) was discriminated from four co-eluting tryptic peptides under lock mass conditions (m/z 785.8426). S-nitrosothiol in the tryptic peptide, ITDFGLBKEGIK (B: CAM, [M + 2H](2+) = 690.86, Found: 690.83), is believed to be present at a very low level, since the threshold for the CMC immonium trigger ions was set at 3 counts/s in the MS survey. The high levels of NO that are produced under stress conditions may result in increased S-nitrosylation of Cys(296) which blocks disulfide bond formation between Cys(296) and Cys(310) and suppresses the biological effects of PKB alpha/Akt1. With the procedures developed here, this process can be studied under physiological and pathological conditions.     

Volumetric studies and thermodynamics of viscous flow of hydroxamic acids in acetone + water solvent at temperatures 303.15 and 313.15 K

Densities ρ and viscosities η of two hydroxamic acids, N-phenyl-2-chlorobenzo- and N-o-tolyl-4-chlorobenzo-, have been determined as a function of their concentration in aqueous acetone solution at temperatures 303.15 and 313.15 K. Apparent molar volumes, standard-state partial molar volumes and relative viscosities have been calculated. The viscosity data have been analyzed using Jones-Dole equation. The activation thermodynamic parameters of viscous flow have been evaluated using Feakins equation. These were obtained to throw light on the mechanism of viscous flow. Thermodynamic interactions in solutions have been studied in terms of a number of excess functions calculated from the experimental data. The effect of hydroxamic acid concentration and temperature on these parameters has been discussed. The results were interpreted in the light of solute-solvent interactions in aquo-organic media.     

Coupled-column liquid chromatography method with photochemically induced derivatization for the direct determination of benzoylureas in vegetables

The coupled-column (LC-LC) system, consisting of a first column packed with internal surface reversed phase (ISRP) (50 x 4.6mm ID) and a Chrompack C18 (100 x 4.6 mm ID) as second column, allowed the simultaneous determination of five benzoylurea insecticides in dichloromethane (CH2Cl2) extracts of vegetable samples without any clean-up step. This system was combined with a photochemically induced fluorescence (PIF) post-column derivatization in order to provide strongly fluorescent photoproducts from the non-fluorescent benzoylureas. Limits of detection ranged from 0.21 to 0.98 microg L(-1) of pesticide (equivalent to 0.14-0.65 microg kg(-1) in vegetable samples) and limits of determination ranged from 4.0 to 10.0 microg L(-1) (equivalent to 2.7-6.7 microg kg(-1)). Linearity of the method was established between 2 and 1800 microg L(-1), depending upon the compound. Validation of the total method was performed by randomly analyzing recoveries of four vegetable samples (aubergine, cucumber, green bean, and tomato) spiked at two levels of concentration (10.0 and 33.3 microg kg(-1)). The combination of the LC-LC system with PIF detection provides a sensitive, selective, and rapid method for the determination of pesticides in vegetable samples at levels lower than the maximum residue levels (MRLs) established for these compounds by Spanish legislation.     

稀土元素在钢中的热力学参数及应用

综合报道了通过采用几种不同的高温金属溶液实验方法，研究所得到的稀土元素在金属溶液冶炼温度范围内分别与硫、氧、氧 硫、碳、氮、低熔点铜、磷、钛、铌、钒等重要元素相互作用规律及有关的一系列热力学参数和温度函数式，并简要地讨论了这些热力学参数在含稀土钢中的应用。     

Evaluation of the limit of performance of an analytical method based on a statistical calculation of its critical concentrations according to ISO standard 11843: Application to routine control of banned veterinary drug residues in food according to European Decision 657/2002/EC

Traceability of the measurement of analytical parameters capable of evaluating the performance of methods is an important concept for the assessment of quality for the routine control, especially for residue monitoring of non-authorized medicinal substances in food from animal origin. The European Decision no. 657/2002/EC recommends to calculate two statistical limits, CCα and CCβ, which allow to evaluate the critical concentrations above which the method reliably distinguish and quantify a substance taking into account the variability of the method and the statistical risk to take a wrong decision. The calculation, which can be derived from the ISO standard no. 11843 is applied on a routine basis. An example displays a very simple way for evaluating the performance of an LC-MSMS method which has been validated a few years ago and is qualified onto a Micromass Quattro LCZ tandem mass spectrometer to monitor and confirm the nitrofuran metabolite residues in food from animal origin. Community Reference Laboratory for Antimicrobial Veterinary Drug Residue Control in Food from Animal Origin     

将A-L理论推广到无限维李代数

为使由Alhassid与Levine所提出的动力学李代数方法（简称A－L理论）能适用于更多的散射体系，在h(∞)中引入了有效集合C（有限维）的概念．按照微扰理论的意义，C中的代数元所对应的群参量是较低次微扰的结果，而不属于C的代数元所对应的群参量则相当于较高次做扰所产生的修正结果．因此可以近似地利用C来代替h(∞)．这样，不仅简化了计算程序并且对于很多具有现实意义的散射过程的计算成为可能．     

The effect of injection procedures on efficiency in micellar electrokinetic capillary chromatography

Summary Micellar electrokinetic capillary chromatography (MECC) involves the application of a high voltage (10–30 KV) across a capillary column (75μm i.d.) which is filled with a solution containing micelles. The mobile phase in this work consisted of sodium dodecyl sulfate in an aqueous borate/phosphate buffer system. Injection parameters in MECC were investigated to minimize the contribution to band-broadening resulting from the injection process. Efficiencies as high as 240,000 theoretical plates/meter are reported.