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51.
Teobald Kupka Hong Ming Lin Leszek Stobiski Cheng‐Han Chen Wei‐Jen Liou Roman Wrzalik Zygmunt Flisak 《Journal of Raman spectroscopy : JRS》2010,41(6):651-658
An attempt to explain the origin of the vivid red color in precious pink and red corals was undertaken. Raman and IR spectroscopies were applied to characterize white, pink and red corals. The position of the Raman signal near 1500 cm−1 of some corals and pearls was associated by several authors with the presence of the mixture of all‐trans‐polyenic pigments, containing 6–16 conjugated CC bonds or β‐carotenoids. This hypothesis was examined theoretically by performing extensive B3LYP‐DFT calculations of vibrational spectra of the model polyenic compounds. The B3LYP/6‐311++G** predicted positions of the dominating Raman mode depend on the number of CC units (Cn parameter) and can be accurately predicted for larger systems from a simple nonlinear fit. The DFT‐predicted Raman activities of these modes are extremely sensitive to Cn, and sharply increase with the number of double bonds. This implies a presence of only—two to three polyenes differing slightly in the number of CC units as the source of color in pink and red corals. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
52.
Daria L. Melnikova Zilya F. Badrieva Mikhail A. Kostin Corina Maller Monika Stas Aneta Buczek Malgorzata A. Broda Teobald Kupka Anne-Marie Kelterer Peter M. Tolstoy Vladimir D. Skirda 《Molecules (Basel, Switzerland)》2020,25(23)
In this work, the nuclear magnetic resonance (NMR) and IR spectroscopic markers of the complexation between 5-fluorouracil (5-FU) and β-cyclodextrin (β-CD) in solid state and in aqueous solution are investigated. In the attenuated total reflectance(ATR) spectra of 5-FU/β-CD products obtained by physical mixing, kneading and co-precipitation, we have identified the two most promising marker bands that could be used to detect complex formations: the C=O and C-F stretching bands of 5-FU that experience a blue shift by ca. 8 and 2 cm−1 upon complexation. The aqueous solutions were studied by NMR spectroscopy. As routine NMR spectra did not show any signs of complexation, we have analyzed the diffusion attenuation of spin–echo signals and the dependence of the population factor of slowly diffusing components on the diffusion time (diffusion NMR of pulsed-field gradient (PFG) NMR). The analysis has revealed that, at each moment, ~60% of 5-FU molecules form a complex with β-CD and its lifetime is ca. 13.5 ms. It is likely to be an inclusion complex, judging from the independence of the diffusion coefficient of β-CD on complexation. The obtained results could be important for future attempts of finding better methods of targeted anticancer drug delivery. 相似文献
53.
H. Román-Flores Y. Chalco-Cano G.N. Silva Ji?í Kupka 《Chaos, solitons, and fractals》2011,44(11):990-994
Let (X, d) be a compact metric space and f : X → X a continuous function. Consider the hyperspace (K(X),H) of all nonempty compact subsets of X endowed with the Hausdorff metric induced by d, and let (F(X),d∞) be the metric space of all nonempty compact fuzzy set on X equipped with the supremum metric d∞ which is calculated as the supremum of the Hausdorff distances of the corresponding level sets. If is the natural extension of f to (K(X),H) and is the Zadeh’s extension of f to (F(X),d∞), then the aim of this paper is to study the dynamics of and when f is turbulent (erratic, respectively). 相似文献
54.
Kupka T Stachów M Nieradka M Kaminsky J Pluta T Sauer SP 《Magnetic resonance in chemistry : MRC》2011,49(5):231-236
It is shown that a linear correlation exists between nuclear shielding constants for nine small inorganic and organic molecules (N(2), CO, CO(2), NH(3), CH(4), C(2)H(2), C(2)H(4), C(2)H(6) and C(6)H(6)) calculated with 47 methods (42 DFT methods, RHF, MP2, SOPPA, SOPPA(CCSD), CCSD(T)) and the aug-cc-pVTZ-J basis set and corresponding complete basis set results, estimated from calculations with the family of polarization-consistent pcS-n basis sets. This implies that the remaining basis set error of the aug-cc-pVTZ-J basis set is very similar in DFT and CCSD(T) calculations. As the aug-cc-pVTZ-J basis set is significantly smaller, CCSD(T)/aug-cc-pVTZ-J calculations allow in combination with affordable DFT/pcS-n complete basis set calculations the prediction of nuclear shieldings at the CCSD(T) level of nearly similar accuracy as those, obtained by fitting results obtained from computationally demanding pcS-n calculations at the CCSD(T) limit. A significant saving of computational efforts can thus be achieved by scaling inexpensive CCSD(T)/aug-cc-pVTZ-J calculations of nuclear isotropic shieldings with affordable DFT complete basis set limit corrections. 相似文献
55.
R. Russow H.-J. Kupka A. Götz B. Apelt 《Isotopes in environmental and health studies》2013,49(4):215-225
Abstract The standard method for determining the 15N abundance of total dissolved nitrogen (TDN) in aqueous samples (e.g., soil leachate, sewage, urine) is currently Kjeldahl digestion followed by steam distillation or diffusion to isolate the ammonium, and then 15N measurement using IRMS. However, this technique is both time-consuming and laborious. One way of overcoming these disadvantages could be to couple a TOC analyser to determine the TDN with a sufficient quadrupole MS to determine the 15N abundance. The highTOC analyser (Elementar Analysensysteme Hanau, Germany), which catalytically oxidises the sample's total nitrogen with a high, constant yield to nitrogen monoxide (NO), appeared particularly suitable. The quadrupole-MS ESD 100 (InProcess Instruments Bremen, Germany) proved to be a suitable mass spectrometer for the 15N determination of NO. This combination of instruments was found to provide a workable method in numerous measurements of standard and actual samples. The detection limit concerning the N amount required per analysis is 2 μg, corresponding to an N concentration of 0.7mg/l in a maximum sample volume of 3ml. Depending on the N concentration, 15N abundances starting from 0.5 at.% can be measured with the required precision of better than 3% (simple standard deviation). For example, measuring the abundance of 0.5 at.% requires about 50 μg N, whereas for 1 at.% or more only about 5 μg N is needed per analysis. 相似文献
56.
H. Kupka 《Molecular physics》2013,111(3):685-693
A general method for calculating the overall shape of the spectrum of vibronic induced transitions in transition-metal ion systems is developed. The vibronic structure is expressed in terms of a weighted sum of medium induced lorentzian lines located at the frequencies of the fundamental odd vibrations of the complex. Each of these lines is followed by a series of vibronic lines assigned to the combination frequencies with one or more even vibrations. The relative intensities of these combination lines are determined by the values of an intramolecular distribution which includes both the effects of geometry and frequency changes of the modes involved in the transition. Values of the linear and the quadratic parameter for the molecule can be estimated from a fit to the experimental spectra. 相似文献
57.
Radula-Janik Klaudia Kupka Teobald Ejsmont Krzysztof Daszkiewicz Zdzisław Sauer Stephan P. A. 《Structural chemistry》2016,27(1):199-207
Structural Chemistry - The first report on crystal and molecular structure of 3,6-diiodo-9-ethyl-9H-carbazole is presented. Experimental room-temperature X-ray and 13C chemical shift studies were... 相似文献
58.
Teobald Kupka Elżbieta Chełmecka Karol Pasterny Michał Stachów Leszek Stobiński 《Magnetic resonance in chemistry : MRC》2012,50(2):142-151
Linearly conjugated benzene rings (acenes), belt‐shaped molecules (cyclic acenes), and models of single‐walled carbon nanotubes (SWCNTs) with one carboxylic group at the open end were fully optimized at the B3LYP/6‐31G* level of theory. These models were selected to obtain some insight into the nuclear isotropic changes resulting from systematically increasing the basic building units of open‐tip‐monocarboxylated SWCNTs. In addition, the position of radial breathing mode (RBM), empirically correlated with the SWCNT diameter, was directly related with the radius of model cyclic acene rings. A regular convergence of selected structural, NMR, and Raman parameters with the molecular system size increase was observed, and a simple two‐parameter mathematical formula enabled their estimation in infinity. The predicted 13C NMR chemical shifts of carbon atoms close to the substituted rim of carboxylated models of zigzag (4,0) SWCNTs differed significantly from the pristine nanotubes. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
59.
Bose-Einstein condensation of magnons in superfluid 3He-B is experimentally manifested by various states where coherent spin precession is established spontaneously, even in nonhomogeneous magnetic fields. Once such a condensate with coherent spin precession is created, it occupies the state with minimal energy, the ground state. The application of an additional magnetic field to that condensate may cause its deflection from the energy minimum and the condensate responds by creating collective gapless oscillations known as Goldstone modes. This Letter reports the experimental observation of a new (non-)Goldstone mode, which can be viewed as an additional NMR mode of condensed magnons in a rotating frame of reference. 相似文献
60.
The non-monotonous course of electroluminescent emission as a function of frequency with relative maxima for 16 KHz and 25 KHz is found experimentally. The phenomenon measured was expounded as electroluminescent resonance (Harman G. G.: J. Electrochem. Soc.104 (1957), 114C.) and its theory is presented.The measurements were performed in the Department of Physics of the Institute of Mechanical and Textile Engineering in Liberec. 相似文献