Development and Optimisation of HILIC-LC-MS Method for Determination of Carbohydrates in Fermentation Samples

Saccharides are the most common carbon source for Streptococcus thermophilus, which is a widely used bacterium in the production of fermented dairy products. The performance of the strain is influenced by the consumption of different saccharides during fermentation. Therefore, a precise measurement of the concentrations of saccharides in the fermentation media is essential. An 18-min long method with limits of quantitation in the range of 0.159–0.704 mg/L and with ¹³C labelled internal standards employing hydrophilic interaction chromatography coupled to mass spectrometric detection-(HILIC-LC-MS) allowed for simultaneous quantification of five saccharides: fructose, glucose, galactose, sucrose, and lactose in the fermentation samples. The method included a four-step sample preparation protocol, which could be easily applied to high-throughput analysis. The developed method was validated and applied to the fermentation samples produced by Streptococcus thermophilus.     

In situ control of surface molecular order in liquid crystals using a localised polymer network and its application to electro-optical devices

A liquid crystal (LC) alignment technique has been developed that allows local control of the polar pretilt angle over the range of 0–90°. This was achieved through the formation of a polymer network localised in the vicinity of the LC cell substrates. The network was formed as a result of in situ UV-induced polymerisation of a photo-reactive monomer added at concentrations of 0.5–1%. Localisation of the polymer network at the LC–substrate boundary was achieved by the application of a high voltage before polymerisation. The resultant pretilt angle was determined by the voltage applied during the polymerisation and/or the duration of the voltage application before the polymerisation step. The desired pretilt angle could be set over a small area of the sample, which allows the fabrication of LC devices with spatially variable optical retardation. Using this method we fabricated a converging lens, a bi-prism, and a phase diffraction grating with resolution greater than 50 lines mm^?1.     

标准元素分析方法的变更及其性能的改进

本文详细地论述了标准元素分析方法的变更及其性能的改进。     

Exponentially Small Splitting of Separatrices Under Fast Quasiperiodic Forcing

We consider fast quasiperiodic perturbations with two frequencies (1/ɛ,γ/$epsiv;) of a pendulum, where γ is the golden mean number. The complete system has a two-dimensional invariant torus in a neighbourhood of the saddle point. We study the splitting of the three-dimensional invariant manifolds associated to this torus. Provided that the perturbation amplitude is small enough with respect to ɛ, and some of its Fourier coefficients (the ones associated to Fibonacci numbers), are separated from zero, it is proved that the invariant manifolds split and that the value of the splitting, which turns out to be exponentially small with respect to ɛ, is correctly predicted by the Melnikov function. Received: 19 February 1996 / Accepted: 14 February 1997     

Abstract theory of universal series and an application to Dirichlet series

We present an abstract theory of universal series; in particular, we give a necessary and sufficient condition for the existence of universal series of a certain type. Most of the known results can be proved or strengthened by using this condition. We also obtain new results, for example, related to universal Dirichlet series. To cite this article: V. Nestoridis, C. Papadimitropoulos, C. R. Acad. Sci. Paris, Ser. I 341 (2005).     

Extensions of the disc algebra and of Mergelyanʼs theorem

We investigate the uniform limits of the set of polynomials on the closed unit disc $\overline{D}$ with respect to the chordal metric χ. More generally, we examine analogous questions replacing $\mathbb{C}\cup \{\infty \}$ by other metrizable compactifications of $\mathbb{C}$.     

68Zn isotope exchange experiments reveal an unusual kinetic lability of the metal ions in the di-zinc form of IMP-1 metallo-beta-lactamase

The apparently paradoxical behaviour of facile exchange (kinetic lability) of tightly bound (thermodynamic stability) zinc ions in the enzyme IMP-1 metallo-beta-lactamase with Zn-68 and cadmium ions, as indicated by in-torch vaporization inductively-coupled plasma mass spectrometry (ITV-ICP-MS) and electrospray-ionization mass spectrometry (ESI-MS), is consistent with the involvement of a third metal ion in promoting Lewis acid/base type exchange processes.     

Universal Taylor series have a strong form of universality

We prove that a function f holomorphic in a simply connected domain Ω whose Taylor series at ξ ∈ Ω is universal with respect to overconvergence automatically has a strong kind of universality: its expansion in Faber series corresponding to any connected compact set Γ ⊂ Ω with connected is universal, and we may take a supremum over all such Γ’s in a compact set. The topology used here is the Carathéodory topology. This answers a question of Mayenberger and Müller. This research is co-funded by the European Social Fund and National Resources-(EPEAEK II) PYTHAGORASII.