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101.
102.
Monika Skowron Robert Zakrzewski Witold Ciesielski 《Journal of Analytical Chemistry》2016,71(8):808-813
A sensitive and convenient method for sphingomyelin determination was developed based on thinlayer chromatography (TLC) and image-processing analysis. The mobile phase composition, detection and quantification conditions were systematically investigated through several trials. The molybdenum blue reaction allowed specific detection of the phospholipid with a high sensitivity and a wide linear range. Digital images of TLC plate chromatograms were captured with flatbed scanner and converted into peak chromatograms using TLSee® software and quantitative analysis was conducted. The linearity, sensitivity, accuracy and precision of the system were evaluated. The limits of detection and quantification were 0.5 and 1.7 μg/spot, respectively. Separation of the mixture consisting of sphingomyelin, phosphatidylcholine, and phosphatidylethanolamine was also carried out. 相似文献
103.
Laxman Mainali Jason W. Sidabras Theodore G. Camenisch Joseph J. Ratke Marija Raguz James S. Hyde Witold K. Subczynski 《Applied magnetic resonance》2014,45(12):1343-1358
Spin-label W-band (94 GHz) electron paramagnetic resonance (EPR) with a five-loop–four-gap resonator (LGR) was successfully applied to study membrane properties (Mainali et al. J Magn Reson 226:35–44, 2013). In that study, samples were equilibrated with the selected gas mixture outside the resonator in a sample volume ~100 times larger than the sensitive volume of the LGR and transferred to the resonator in a quartz capillary. A seven-loop–six-gap W-band resonator has been developed. This resonator permits measurements on aqueous samples of 150 nL volume positioned in a polytetrafluoroethylene (PTFE) gas permeable sample tube. Samples can be promptly deoxygenated or equilibrated with an air/nitrogen mixture inside the resonator, which is significant in saturation-recovery measurements and in spin-label oximetry. This approach was tested for lens lipid membranes derived from lipids extracted from two porcine lenses (single donor). Profiles of membrane fluidity and the oxygen transport parameter were obtained from saturation-recovery EPR using phospholipid analog spin-labels. Cholesterol analog spin-labels allowed discrimination of the cholesterol bilayer domain and acquisition of oxygen transport parameter profiles across this domain. Results were compared with those obtained previously for membranes derived from a pool of 100 lenses. Results demonstrate that EPR at W-band can be successfully used to study aqueous biological samples of small volume under controlled oxygen concentration. 相似文献
104.
Generalized Fourier transformation between the position and the momentum representation of a quantum state is constructed in a coordinate independent way. The only ingredient of this construction is the symplectic (canonical) geometry of the phase-space: no linear structure is necessary. It is shown that the “fractional Fourier transform” provides a simple example of this construction. As an application of this technique we show that for any linear Hamiltonian system, its quantum dynamics can be obtained exactly as the lift of the corresponding classical dynamics by means of the above transformation. Moreover, it can be deduced from the free quantum evolution. This way new, unknown symmetries of the Schrödinger equation can be constructed. It is also argued that the above construction defines in a natural way a connection in the bundle of quantum states, with the base space describing all their possible representations. The non-flatness of this connection would be responsible for the non-existence of a quantum representation of the complete algebra of classical observables. 相似文献
105.
106.
Xin Wang Xiaodong Liu Witold PedryczXiaolei Zhu Guangfei Hu 《European Journal of Operational Research》2012,218(1):202-210
In this paper, we propose a novel method to mine association rules for classification problems namely AFSRC (AFS association rules for classification) realized in the framework of the axiomatic fuzzy set (AFS) theory. This model provides a simple and efficient rule generation mechanism. It can also retain meaningful rules for imbalanced classes by fuzzifying the concept of the class support of a rule. In addition, AFSRC can handle different data types occurring simultaneously. Furthermore, the new model can produce membership functions automatically by processing available data. An extensive suite of experiments are reported which offer a comprehensive comparison of the performance of the method with the performance of some other methods available in the literature. The experimental result shows that AFSRC outperforms most of other methods when being quantified in terms of accuracy and interpretability. AFSRC forms a classifier with high accuracy and more interpretable rule base of smaller size while retaining a sound balance between these two characteristics. 相似文献
107.
Niko Guskos Spiros Glenis Janusz Typek Grzegorz Zolnierkiewicz Pawel Berczynski Kamil Wardal Aleksander Guskos Daniel Sibera Dariusz Moszyński Witold Lojkowski Urszula Narkiewicz 《Central European Journal of Physics》2012,10(2):470-477
Fine particles of ZnFe2O4 were synthesized by a wet chemical method in the (80 wt.% Fe2O3 + 20 wt.% ZnO) system. The morphological and structural properties of the mixed system were investigated by scanning electron microscopy, X-ray diffraction, inductively coupled plasma atomic emission, and X-ray photoelectron spectroscopy. The major phase was determined to be the ZnFe2O4 spinel with particle size of 11 nm. The magnetic properties of the material were investigated by ferromagnetic resonance (FMR) in the temperature range from liquid helium to room temperature. A very intense, asymmetric FMR signal from ZnFe2O4 nanoparticles was recorded, which has been analyzed in terms of two Callen-lineshape lines. Temperature dependence of the FMR parameters was obtained from fitting the experimental lines with two component lines. Analysis of the FMR spectra in terms of two separate components indicates the presence of strongly anisotropic magnetic interactions. 相似文献
108.
Władysław Piotrowski Koen Lodefier Slawomir Kubacki Witold Elsner Erik Dick 《Flow, Turbulence and Combustion》2008,81(3):369-394
The present paper evaluates two unsteady transition modelling approaches: the prescribed unsteady intermittency method PUIM,
developed at Cambridge University and the dynamic unsteady intermittency method developed at Ghent University. The methods
are validated against experimental data for the N3-60 steam turbine stator profile for steady and for unsteady inlet flow
conditions. The characteristic features of the test case are moderately high Reynolds number and high inlet turbulence intensity,
which causes bypass transition. The tested models rely both on the intermittency parameter and are unsteady approaches. In
the prescribed method, the time-dependent intermittency distribution is obtained from integral relations. In the dynamic method,
the intermittency distribution follows from time-dependent differential equations. For unsteady computations, self-similar
wake profiles are prescribed at the inlet of the computational domain. Joint validation of the prescribed and the dynamic
unsteady intermittency models against experimental data shows that both methods are able to reproduce the global features
of the periodical evolution of the boundary layer under the influence of a periodically impinging wake. The overall quality
of the dynamic method is better than that of the prescribed method. 相似文献
109.
110.
Sergio Albeverio Jens-Erik Fenstad Raphael Høegh-Krohn Witold Karwowski Tom Lindstrøm 《Physics letters. A》1984,104(8):396-400
We discuss hamiltonians in L2(Rd, dx) of the form H = ?Δ + V, with V a potential supported by a zero measure set C. In particular if C is a path of a brownian motion b such that V(x) = ∫01λ(x, ω)δ(x-b(s, ω)) ds, we show that H exists as a nontrivial, self-adjoint, lower bounded perturbation of ?Δ when d ?5. We must choose λ to be an infinitesimal, negative function for d = 4,5, but for d ? 3 any bounded real-valued function λ will do. The connection with Edward's model of polymers as well as with quantum fields of the ?d4-type is also discussed. The proofs use methods of nonstandard analysis. 相似文献