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651.
S. N. Lea 《The European physical journal. Special topics》2008,163(1):37-53
Comparisons between frequency standards based on optical and microwave transitionsin atoms and ions currently provide the
most stringent laboratory limitson present-day local variation of the fundamental constants.This paper discusses the sensitivity
of these frequency standards to variation ofthe electromagnetic and strong interactions, summarises the constraints onvariation
of these interactions which can be obtained from currently-available data, and discusses the magnitude of improvements in
these limits which is anticipated fromexperiments currently underway. 相似文献
652.
C. Lea 《Fresenius' Journal of Analytical Chemistry》1875,14(1):370
Ohne Zusammenfassung 相似文献
653.
C. Lea 《Fresenius' Journal of Analytical Chemistry》1878,17(1):367
Ohne Zusammenfassung 相似文献
654.
Alan L. Carey Adam Rennie Aleksandr Sedaev Fyodor Sukochev 《Journal of Functional Analysis》2007,249(2):253-283
We obtain general theorems which enable the calculation of the Dixmier trace in terms of the asymptotics of the zeta function and of the trace of the heat semigroup. We prove our results in a general semi-finite von Neumann algebra. We find for p>1 that the asymptotics of the zeta function determines an ideal strictly larger than Lp,∞ on which the Dixmier trace may be defined. We also establish stronger versions of other results on Dixmier traces and zeta functions. 相似文献
655.
Carey Lea 《Fresenius' Journal of Analytical Chemistry》1874,13(1):453
Ohne Zusammenfassung 相似文献
656.
We study both the continuous model and the discrete model of the quantum Hall effect (QHE) on the hyperbolic plane in the presence of disorder, extending the results of an earlier paper. Here we model impurities, that is we consider the effect of a random or almost periodic potential as opposed to just periodic potentials. The Hall conductance is identified as a geometric invariant associated to an algebra of observables, which has plateaus at gaps in extended states of the Hamiltonian. We use the Fredholm modules defined in Comm. Math. Phys. 190 (1998), 629–673, to prove the integrality of the Hall conductance in this case. We also prove that there are always only a finite number of gaps in extended states of any random discrete Hamiltonian. 相似文献
657.
Bernhard Felver David C. King Simon C. Lea Gareth J. Price A. Damien Walmsley 《Ultrasonics sonochemistry》2009,16(5):692-697
Ultrasonic scalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the scaler. The vibratory motion of three designs of scaler tip in a water bath has been characterised by laser vibrometry, and compared with the spatial distribution of cavitation around the scaler tips observed using sonochemiluminescence from a luminol solution. The type of cavitation was confirmed by acoustic emission analysed by a ‘Cavimeter’ supplied by NPL. A node/antinode vibration pattern was observed, with the maximum displacement of each type of tip occurring at the free end. High levels of cavitation activity occurred in areas surrounding the vibration antinodes, although minimal levels were observed at the free end of the tip. There was also good correlation between vibration amplitude and sonochemiluminescence at other points along the scaler tip. ‘Cavimeter’ analysis correlated well with luminol observations, suggesting the presence of primarily transient cavitation. 相似文献
658.
In this paper, we develop differential twisted K-theory and define a twisted Chern character on twisted K-theory which depends on a choice of connection and curving on the twisting gerbe. We also establish the general Riemann–Roch theorem in twisted K-theory and find some applications in the study of twisted K-theory of compact simple Lie groups. 相似文献
659.
An electrospray ionization mass spectrometric (ESI-MS) determination of glutathione (GSH), a sulfur-containing tripeptide (gamma-Glu-Cys-Gly) with regulation and detoxication functions in metabolisms of most living organisms, from nanomolar to micromolar levels is described. A hydrophilic interaction chromatography (HILIC) with an isocratic elution using a mobile phase containing acetonitrile and an aqueous 0.00005% solution of trifluoroacetic acid (60/40%, v/v) was applied for the separation of GSH. The peptide detection was achieved in the presence of L-ascorbic acid which significantly enhanced the signal intensity of the molecular ion GSH [M+H]+ (m/z 308). The calibration curve was linear (R2=0.9995) in the concentration range from 2 nM to 10 microM with a detection limit (LOD, S/N=3) of 0.5 nM. The excellent detection limit, and the excellent selectivity and high reproducibility of this method enabled determination of GSH in a single plant somatic embryo of a Norway spruce (Picea abies). The average amount of GSH in the single somatic embryos (n=18) was 9 pmol per embryo. Owing to our results, it can be supposed that the proposed HILIC/ESI-MS analysis might be used for GSH determination in microscopic cell structures and in single cell analyses. 相似文献
660.
Hill JP Schumacher AL D'Souza F Labuta J Redshaw C Elsegood MR Aoyagi M Nakanishi T Ariga K 《Inorganic chemistry》2006,45(20):8288-8296
5,10,15,20-Tetrakis-3,5-di-tert-butyl-4-oxocyclohexadienylidene porphyrinogen and its di-N-benzylated derivative are solvatochromic dyes capable of binding anionic species. The influence of solvent polarity and hydrogen bonding on their electronic absorption spectra was observed. Hydrogen bonding by the porphyrinogen amine protons of acetone solvent molecules could be observed in the solid state. The acetone solvate of N21N23-dibenzyl-5,10,15,20-tetrakis-3,5-di-tert-butyl-4-oxocyclohexadienylidene porphyrinogen crystallized under anhydrous conditions in the space group P with cell dimensions a = 12.1693(11) A, b = 17.5849(13) A, c = 21.0965(17) A, alpha = 69.870(4) degrees , beta = 78.140(4) degrees , gamma = 82.865(5) degrees . These porphyrinogens are capable of binding a variety of anions and can be used to distinguish fluoride chromogenically from the other halide anions. Solvatochromism was combined with anion binding in an attempt to provide more selective tests for anions. The anion binding properties were investigated using UV/vis spectrophotometry and 1H NMR spectroscopy. 相似文献