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21.
We develop the quantization of topological solitons (vortices) in three-dimensional quantum field theory, in terms of the Euclidean region functional integral. We analyze in some detail the vortices of the abelian Higgs model. If a Chern-Simons term is added to the action, the vortices turn out to be anyons, i.e. particles with arbitrary real spin and intermediate () statistics. Localization properties of the interpolating field, scattering theory and spin-statistics connection of anyons are discussed. Such analysis might be relevant in connection with the fractional quantum Hall effect and two-dimensional models of HighT
csuperconductors. 相似文献
22.
23.
Claudio Albanese Jürg Fröhlich Thomas Spencer 《Communications in Mathematical Physics》1988,119(4):677-699
This is our second paper devoted to the study of some non-linear Schrödinger equations with random potential. We study the non-linear eigenvalue problems corresponding to these equations. We exhibit a countable family of eigenfunctions corresponding to simple eigenvalues densely embedded in the band tails. Contrary to our results in the first paper, the results established in the present paper hold for an arbitrary strength of the non-linear (cubic) term in the non-linear Schrödinger equation. 相似文献
24.
Monot Frédéric Benoit Yves Ballerini Daniel Vandecasteele Jean-Paul 《Applied biochemistry and biotechnology》1990,(1):375-386
Utilization of lipases for synthesis of esters of hydrophilic polyols has been investigated. The choice of a suitable solvent
is crucial in this type of reaction. An interesting case is fatty acid esters from neopentylpolyols, such as trimethylolpropane,
which are of great interest as high temperature lubricants. Enzymatic synthesis of trimethylolpropane tricaprylate was studied
as an alternative to chemical manufacturing. Triester production occurred only if the water produced by esterification was
continuously removed from the medium. In these condition, kinetics of appearance and transformation of mono-, di- and triesters
were determined in order to define optimal conditions. 相似文献
25.
Martinho M Banse F Bartoli JF Mattioli TA Battioni P Horner O Bourcier S Girerd JJ 《Inorganic chemistry》2005,44(25):9592-9596
The green complex S=1 [(TPEN)FeO]2+ [TPEN=N,N,N',N'-tetrakis(2-pyridylmethyl)ethane-1,2-diamine] has been obtained by treating the [(TPEN)Fe]2+ precursor with meta-chloroperoxybenzoic acid (m-CPBA). This high-valent complex belongs to the emerging family of synthetic models of Fe(IV)=O intermediates invoked during the catalytic cycle of biological systems. This complex exhibits spectroscopic characteristics that are similar to those of other models reported recently with a similar amine/pyridine environment. Thanks to its relative stability, vibrational data in solution have been obtained by Fourier transform infrared. A comparison of the Fe=O and Fe=(18)O wavenumbers reveals that the Fe-oxo vibration is not a pure one. The ability of the green complex to oxidize small organic molecules has been studied. Mixtures of oxygenated products derived from two- or four-electron oxidations are obtained. The reactivity of this [FeO]2+ complex is then not straightforward, and different mechanisms may be involved. 相似文献
26.
Summary NAD(P)H fluorescence emission spectra are recorded from single living cells, by a recently developed multichannel microspectrofluorometric technique, in correlation with the intracellular microelectrophoretic addition of substrate (i. e., glucose-6-P). These spectra may be used as a reference basis in establishing the critical parameters to be followed when the same studies are extended to a variety of cells, submitted to various drug effects or physical treatments. The sum-spectra corresponding to channel by channel (wavelength by wavelength) summation of spectra obtained from various cells within a series, before and after addition of substrate, and their difference spectrum may be normalized and evaluated comparatively. The NAD(P)H emission maximum prior to addition of substrate seems to present a mixture of dehydrogenase-bound and free coenzyme. There is a suggestion that immediately after substrate, i. e., at 5 sec, an increase in free NADH is first observed. While the overall changes in fluorescence intensity associated with substrate are quite large (50–150% increase), the counts (i. e., an expression of photons) associated with shifts in the emission maximum (free vs. bound NAD(P)H changes) are at times barely above noise. Rapid microspectrofluorometry provides in principle the most direct approach for the identification of coenzyme bound to various dehydrogenases in single living cells, but further improvements in spectral resolution and signal-to-noise ratio are required, for a better definition of the spectral shifts which may be observed.
Zusammenfassung Mit Hilfe einer kürzlich entwickelten Mehrkanal-Mikrospektrofluorometer-Methode wurden von einzelnen lebenden Zellen nach intrazellulär mikroelektrophoretischer Substratzugabe (z. B. Glucose-6-P) NAD(P)H Fluoreszenz-Emissionsspektren aufgenommen. Diese Spektren können als Vergleichsbasis bei der Festsetzung der entscheidenden Parameter verwendet werden, wenn die gleichen Untersuchungen auf eine Reihe von Zellen ausgedehnt werden sollen, die verschiedenen Medikamenteffekten oder physikalischer Behandlung ausgesetzt werden. Die Summenspektren, die der kanalmäßigen (wellenlängenmäßigen) Summierung der Spektren von verschiedenen Zellen innerhalb einer Serie, vor und nach Substratzugabe entsprechen, sowie ihre Differenzspektren können normalisiert und vergleichsweise ausgewertet werden. Das NAD(P)H-Emissionsmaximum vor der Substratzugabe scheint ein Gemisch von freiem und dehydrogenasegebundenem Coenzym darzustellen. Unmittelbar nach Substratzugabe (d. h. nach 5 sec) ist ein Anstieg an freiem NADH das erste Mal zu beobachten. Während die mit dem Substrat einhergehenden Gesamtveränderungen der Fluoreszenzintensität recht groß sind (50–150% Anstieg), sind die Impulse (als Effekt der Photonen), die mit einer Verschiebung im Emissionsmaximum verbunden sind (Veränderungen von freiem und gebundenem NAD(P)H) zu manchen Zeiten kaum höher als das Rauschen. Die rasche Mikrospektrofluorometrie stellt im Prinzip die direkteste Methode zur Identifizierung von Coenzymen dar, die an verschiedenen Dehydrogenasen in einzelnen lebenden Zellen gebunden sind. Weitere Verbesserungen der Spektralauflösung und der Empfindlichkeit (signal-to-noise ratio) sind notwendig, um die Spektralverschiebungen, die beobachtet werden, besser auswerten zu können.相似文献
27.
A facile synthesis of 2-formyl-1,8-naphthalenediol is reported. Its potential as a general precursor for the preparation of unsymmetrical multidentate chelating ligand systems based on 1,8-naphthalenediol is demonstrated by the synthesis of the dinucleating ligand L(4-)(H(4)L=N,N'-bis(2-(1,8-naphthalenediol)methylidene)propylenediamine). Reaction of H(4) L with copper acetate results in the formation of the unsymmetrical dinuclear Cu(II) complex [LCu(2)](3), which has been structurally characterized by single-crystal X-ray diffraction. One Cu(II) ion is coordinated by a N(2)O(2) compartment of L(4-) and the other Cu(II) ion is coordinated by an O(4) compartment of L(4-) while they are bridged by two aryloxide functions of L(4-). A dimerization of two molecules of 3 to a tetranuclear entity 3(2) occurs through formation of weak apical Cu--O interactions. Analysis of the temperature dependent magnetic susceptibility measurements (2--290 K) established a strong intradimer exchange coupling J(12)=-371 cm(-1). This strong superexchange interaction fits nicely in a magneto-structural correlation which has been established for dinuclear bis(phenoxide)-bridged Cu(II) complexes demonstrating the electronic equivalence of the aryloxides of a phenol and 1,8-naphthalenediol. 相似文献
28.
29.
Summary A reversed-phase high-performance liquid chromatographic (RP-HPLC) method with UV detection (270 nm) for the determination of nitrite as its pentafluorobenzyl derivative with and without ion-pair extraction is described. Ion-pair extraction of nitrite from aqueous solutions was performed by using a 1 mol/l solution of the liquid ion exchanger methyltrioctylammonium chloride in toluene. The residue of the ion-pair extraction or an aliquot of an aqueous nitrite solution or of a biological fluid (100 l) were treated with 400 l of acetone and 10 l of pentafluorobenzyl bromide. Nitrite was converted into its pentafluorobenzyl derivative by heating at 50°C for 90 min. After evaporation of acetone the aqueous phases were diluted with 100 to 400 l of methanol, and up to 100 l were injected into the RP-HPLC system. The method allows accurate analysis of nitrite in the presence of nitrate directly in aqueous solutions and biological fluids in concentrations down to 2.0 mg/l. The method is also applicable to the determination of nitrate following its reduction to nitrite by cadmium. 相似文献
30.
Hemmerlé J Roucoules V Fleith G Nardin M Ball V Lavalle P Marie P Voegel JC Schaaf P 《Langmuir : the ACS journal of surfaces and colloids》2005,21(23):10328-10331
Mechanically responsive surfaces that allow to switch reversibly from a hydrophobic to a hydrophilic substrate are reported. The surfaces are constituted of polyelectrolyte multilayers deposited on modified charged silicone sheets. n bilayers of poly(allylamine)-Nafion (PAH-Naf) and m bilayers of poly(allylamine)-poly(acrylic acid) (PAH-PAA) composed the multilayers. A (PAH-Naf)(n) film possesses a water contact angle of around 105 degrees, whereas the contact angle of a (PAH-Naf)(4)-(PAH-PAA)(m) multilayer is around 50 degrees. When such a film with m < 5 and terminated by PAA is stretched out, its water contact angle increases up to around 100 degrees. Successive elongation/retraction cycles allow the water contact angle to alternate reversibly between 100 and 57 degrees indicating the reversible mechanical responsive nature of the film. 相似文献