Cationic poly(methacryl oxyethyl trimethylammonium) and its poly(ethylene glycol)‐grafted analogue as capillary coating materials in electrophoresis

Cationic polyelectrolytes were synthesized and used as semipermanent coating materials for capillaries in electrophoresis. The polyelectrolytes used were a homopolymer of poly(methacryl oxyethyl trimethylammonium chloride) (PMOTAC) and its poly(ethylene glycol) (PEG)‐grafted analogue. Two PMOTAC polyelectrolytes, with molar masses of 85,000 and 300,000 g/mol, and PEG‐grafted PMOTAC with a molar mass of 280,000 g/mol were synthesized and then characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. Attachment of the polyelectrolytes to the wall of the fused silica capillary for electrophoresis caused the electroosmotic flow (EOF) to reverse. The polyelectrolyte coatings were tested over the pH range 2–11 at different buffer ionic strengths, and the most stable and strongest anodic EOFs were obtained at acidic pH values with low ionic strength buffers. Between runs the capillary is merely rinsed for 2 or 3 min with the background electrolyte solution. With the PMOTAC coatings at pH values ≤5, the RSDs of the EOFs were less than 2.9% after 60 injections. The effects of the molar mass of the polycation and of PEGylation of PMOTAC on the interactions between the polycations and basic proteins were studied at acidic pH values. The differences in the effective electrophoretic mobilities, resolution values, and plate numbers of the proteins with the different coatings were due to the EOF, as demonstrated through calculations of reduced mobilities, relative resolution values, and relative plate numbers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2655–2663, 2007     

Periodic behavior of the stochastic Brusselator in the mean-field limit

Summary We prove a propagation of chaos result for the mean-field limit of a model for a trimolecular chemical reaction called Brusselator. Then we show that the pair of nonlinear (i.e. law-dependent) stochastic differential equations describing the evolution of the concentration of the molecules at a given site in the mean field limit has a solution with a periodic law (in t). Finally we identify the limit and establish a central limit theorem for the periodic law in the case where the noise tends to zero.Part of this work was performed while on leave at the Department of Mathematics and Statistics, Carleton University, Ottawa, Canada and supported by NSERC operating grants of M. Csörgö and D. Dawson     

Beiträge zur Massenspektrometrie der Gelsemium-Alkaloide

Zusammenfassung Von den Nebenalkaloiden vonGelsemium sempervirens (L.) Ait. konnte eine Verbindung, zunächst als Gelsemium-Alkaloid A bezeichnet, in reiner Form dargestellt und ihre Konstitution als N-1-Methoxygelsemin aufgeklärt werden. Für die Strukturermittlung erwies sich die Massenspektrometrie als besonders wertvoll. Die Massenspektren einiger Gelsemiumalkaloide sind wiedergegeben, die Fragmentierung dieser Verbindungen wird diskutiert.Au\erdem wurde eine größere Anzahl neuer Basen in kleiner Menge nachgewiesen.

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Contributions to mass-spectrometry of gelsemium-alkaloids (The structure of gelsemium-alkaloid A)

From the minor alkaloids ofGelsemium sempervirens (L.) Ait., one compound, preliminary designated as Gelsemiumalkaloid A, could be isolated and was identified as N-1-Methoxy-gelsemine. For the structure-elucidation mass-spectrometry has been proven to be of great value. Mass spectra of some Gelsemium-alkaloids are reported and the fragmentation of these compounds is discussed.There were further detected a quantity of new alkaloids in small amounts.

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Mit 7 Abbildungen

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Anmerkung bei der Korrektur (23.10.1972): Während der Drucklegung dieser Arbeit erschien eine Publikation vonE. Wenkert u. Mitarb. [Exper.28, 377 (1972)], in der die Struktur des Gelsevirins als N-1-Methoxy-gelsemin angegeben wird; somit ist Gelsemium-Alkaloid A offensichtlich mit Gelsevirin identisch. Eine solche Identifizierung was uns nicht möglich, da einerseits kein authentisches Präparat von Dr.Marion verfügbar was (Brief von Dr.Edwards, Ottawa, vom 21.6.1971) und andrerseits die wenigen, bisher veröffentlichten Daten über Gelsevirin hierfür nicht ausreichen.     

A sugar's choice: coordination to a mononuclear or a dinuclear copper(II) complex?

We proposed a decisive role of the number of metal ions at the sugar binding site for carbohydrate-coordinating copper(II) complexes. To verify this hypothesis, we studied the binding of the representatively chosen carbohydrates D-ribose (7), D-mannose (8), D-glucose (9), and D-maltose (10) to structurally related mono- and dinuclear copper(II) complexes in alkaline solution. All carbohydrates coordinate to the metal complexes in a 1:1 molar ratio. Coordination of 7 or 8 to the dinuclear copper(II) complex 1 is about 0.5 order of magnitude stronger than the complex formation with related mononuclear complexes. On contrast, 9, which is an epimer of 8, coordinates stronger to either one of the mononuclear copper(II) complexes in alkaline aqueous solution.     

Mikroreflexionsmessungen zur Untersuchung dünner Oberflächenschichten

Zusammenfassung Es wird eine einfache optische Methode zur Dickenbestimmung dünner Oberflächenfilme beschrieben, die sich besonders zur Untersuchung von Korrosionsschichten eignet.

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Investigation of thin corrosion layers by microreflexion measurement

A simple optical method for the determination of thin surface films is described. It is especially suitable for the thin corrosion layer investigation.

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Meinem verehrten Lehrer, Prof. Dr.H. Nowotny, gewidmet.     

Über assoziierte lineare und lokalkonvexe Topologien

Certain properties E of linear topological or locally convex spaces induce a functor in the corresponding category, which assigns to every space (X,F) an associated topologyF ^E. The well-known notions of the coarsest barrelled topology stronger than a given locally convex topology or of the strongest locally convex topology weaker than a given linear topology are examples of this concept. In the first two parts of this paper we consider the problem, whether the above functors commute with other processes, such as forming products, linear and locally convex direct sums, inductive limits and completions. With help of two technical lemmas we prove in the third part, that every separated locally convex space is a quotient of a complete locally convex space, in which every bounded set has a finite dimensional linear span. This sharpens results of Y. Kōmura [12], M. Valdivia [18] and W.J. Wilbur [20].     

Evaluation of aortic stenosis severity using 4D flow jet shear layer detection for the measurement of valve effective orifice area

Aims

The objective of this study was to evaluate the potential of 4D flow MRI to assess valve effective orifice area (EOA) in patients with aortic stenosis as determined by the jet shear layer detection (JSLD) method.

Methods and Results

An in-vitro stenosis phantom was used for validation and in-vivo imaging was performed in 10 healthy controls and 40 patients with aortic stenosis. EOA was calculated by the JSLD method using standard 2D phase contrast MRI (PC-MRI) and 4D flow MRI measurements (EOA_JSLD-2D and EOA_JSLD-4D, respectively). As a reference standard, the continuity equation was used to calculate EOA (EOA_CE) with the 2D PC-MRI velocity field and compared to the EOA_JSLD measurements. The in-vitro results exhibited excellent agreement between flow theory (EOA = 0.78 cm²) and experimental measurement (EOA_JSLD-4D = 0.78 ± 0.01 cm²) for peak velocities ranging from 0.9 to 3.7 m/s. In-vivo results showed good correlation and agreement between EOA_JSLD-2D and EOA_CE (r = 0.91, p < 0.001; bias: − 0.01 ± 0.38 cm²; agreement limits: 0.75 to − 0.77 cm²), and between EOA_JSLD-4D and EOA_CE (r = 0.95, p < 0.001; bias: − 0.09 ± 0.26 cm²; limits: 0.43 to − 0.62 cm²).

Conclusion

This study demonstrates the feasibility of measuring EOA_JSLD using 4D flow MRI. The technique allows for optimization of the EOA measurement position by visualizing the 3D vena contracta, and avoids potential sources of EOA_CE measurement variability.     

Relating field theories via stochastic quantization

This note aims to subsume several apparently unrelated models under a common framework. Several examples of well-known quantum field theories are listed which are connected via stochastic quantization. We highlight the fact that the quantization method used to obtain the quantum crystal is a discrete analog of stochastic quantization. This model is of interest for string theory, since the (classical) melting crystal corner is related to the topological A-model. We outline several ideas for interpreting the quantum crystal on the string theory side of the correspondence, exploring interpretations in the Wheeler–De Witt framework and in terms of a non-Lorentz invariant limit of topological M-theory.     

Silica‐Coating of Hematite Nanoparticles Using Reactive Water‐Soluble Polyalkoxysiloxanes

In this article, we report on a new one‐step synthetic route to obtain multi‐functional silica‐coated hematite particles using a water‐based surfactant‐free technology. The synthesis and properties of uniform silica‐coated hematite particles with adjustable size, morphology, and silica shell thickness are discussed in detail. The developed method allows simultaneous formation of the silica shell around hematite core and incorporation of reactive groups on the surface of core–shell nanoparticles. Vinyl groups are introduced to the silica surface at once by pre‐functionalization of a water‐soluble hyperbranched polyalkoxysiloxanes with active double bonds. The reactivity of these surface‐immobilized vinyl groups is demonstrated by covalent attachment of rhodamine B using a thiol‐en click reaction.