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11.
12.
A. Perjéssy H. K. Al‐Amood G. F. Fadhil N. Prónayová 《Journal of Physical Organic Chemistry》2011,24(2):140-146
A series of substituted chlorinated chalcones namely, 3‐(2,4‐dichlorophenyl)‐1‐(4′‐X‐phenyl)‐2‐propen‐1‐one, have been synthesized, X being H, NH2, OMe, Me, F, Cl, CO2Et, CN, and NO2. Dual substituent parameter (DSP) models of 13C NMR chemical shift (CS) have revealed that π‐polarization concept could be utilized to explain the reverse field effect at CO, the enhanced substituent field effect at CO, C‐2, and C‐5, and the decreased sensitivity of substituent field effect at C‐6. Chlorine atoms dipole direction at the benzylidene ring either enhances or reduces substituent effect depending on how they couple with the substituent dipole at the probe site. The correlation of 13C NMR CS of C‐2, C‐5, and C‐6 with σ and σ indicates that chlorine atoms in the benzylidine ring deplete the ring from charges. Both MSP of Hammett and DSP of Taft 13C NMR CS models give similar trends of substituent effects at C‐2, C‐5, and C‐6. However, the former fail to give a significant correlation for CO and C‐6 13C NMR CS. MSP of σq and DSP of Taft and Reynolds models significantly correlated 13C NMR CS of Cβ. MSP of σq fails to correlate C‐1′ 13C NMR CS. Investigation of 13C NMR CS of non‐chlorinated chalcones series: 3‐phenyl‐1‐(4′‐X‐phenyl)‐2‐propen‐1‐one has revealed similar trends of substituent effects as in the chlorinated chalcones series for C‐1′, CO, Cα, and Cβ. In contrast, the substituent effect of the non‐chlorinated chalcone series at C‐2, C‐5, and C‐6 did not correlate with any substituent constant. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
13.
In fields such as food and nutrition science or plant physiology, interest in untargeted profiling of flavonoids continues to expand. The group of flavonoids encompasses several thousands of chemically distinguishable compounds, among which are a number of isobaric compounds with the same elemental composition. Thus, the mass spectrometric identification of these compounds is challenging, especially when reference standards are not available to support their identification. Many different types of isomers of flavonoid glycoconjugates are known, i.e. compounds that differ in their glycosylation position, glycan sequence or type of interglycosidic linkage. This work focuses on the mass spectrometric identification of flavonoid glycoconjugate isomers possessing the same glycan mass and differing only in their aglycone core. A non‐targeted HPLC‐ESI‐MS/MS profiling method using a triple quadrupole MS is presented herein, which utilizes in‐source fragmentation and a pseudo‐MS3 approach for the selective analysis of flavonoid glycoconjugates with isomeric/isobaric aglycones. A selective MRM‐based identification of the in‐source formed isobaric aglycone fragments was established. Additionally, utilizing the precursor scanning capability of the employed triple quadrupole instrument, the developed method enabled the determination of the molecular weight of the studied intact flavonoid glycoconjugate. The versatility of the method was proven with various types of flavonoid aglycones, i.e. anthocyanins, flavonols, flavones, flavanones and isoflavones, along with their representative glycoconjugates. The developed method was also successfully applied to a commercially available sour cherry sample, in which 16 different glycoconjugates of pelargonidin, genistein, cyanidin, kaempferol and quercetin could be tentatively identified, including a number of compounds containing isomeric/isobaric aglycones. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
14.
Istvá n Juhá sz Peter Nyikos Zoltá n Szentmikló ssy 《Proceedings of the American Mathematical Society》2005,133(9):2741-2750
We give restrictions on the cardinality of compact Hausdorff homogeneous spaces that do not use other cardinal invariants, but rather covering and separation properties. In particular, we show that it is consistent that every hereditarily normal homogeneous compactum is of cardinality . We introduce property wD(), intermediate between the properties of being weakly -collectionwise Hausdorff and strongly -collectionwise Hausdorff, and show that if is a compact Hausdorff homogeneous space in which every subspace has property wD( ), then is countably tight and hence of cardinality . As a corollary, it is consistent that such a space is first countable and hence of cardinality . A number of related results are shown and open problems presented.
15.
A. Perjéssy 《Tetrahedron》1973,29(20):3207-3212
The use of the improved Seth-Paul-Van Duyse equation (SPVDE) provides a new statistically significant method for determination of transmissive factors of polar effects for various bridge groups. The method was applied to the CO stretching frequencies of s-cis and s-trans conformers of 98 R1CHCHCOR2 compounds. The transmissive factors for CHCH group in both conformations s-cis and s-trans have been calculated with an accuracy about of one order higher than found by using the methods described earlier. The applicability of the improved SPVDE to the 137 CO stretching frequencies of various R1CHCHCOR2 compounds has been proved. 相似文献
16.
Es wurde festgestell, daβ Silberionen an mit wasserstoffgesättigten Platimpulver sich abschieden und die maximal abgeschiedence Menge im Salpeterāure-Konzentrationsbereich 5 n – 0,0001 n die der Monoshcict entsprechende Menge nicht erreicht. Die Meβergebnisse bezüglich der Konzentrationsabhängigkeit der Abscheidung scheinen formell die Langmuirsche Gleichung zu erfūllen, doch zeigen die aus dieser Gleichung berechneten Tσ - Werte eine pH-Abhāngigkeit und stimmen mit der BET-Ober-fläche nicht überein. Die spontne Abscheidung von Silber an Platinpulver kann für die Abtennung von radioaktiven Silber-Isotopen angewandt werden. 相似文献
17.
The distance function \({\varrho(p, q) ({\rm or} d(p, q))}\) of a distance space (general metric space) is not differentiable in general. We investigate such distance spaces over \({\mathbb{R}^n}\), whose distance functions are differentiable like in case of Finsler spaces. These spaces have several good properties, yet they are not Finsler spaces (which are special distance spaces). They are situated between general metric spaces (distance spaces) and Finsler spaces. We will investigate such curves of differentiable distance spaces, which possess the same properties as geodesics do in Finsler spaces. So these curves can be considered as forerunners of Finsler geodesics. They are in greater plenitude than Finsler geodesics, but they become geodesics in a Finsler space. We show some properties of these curves, as well as some relations between differentiable distance spaces and Finsler spaces. We arrive to these curves and to our results by using distance spheres, and using no variational calculus. We often apply direct geometric considerations. 相似文献
18.
T.?S.?Biró G.?Purcsel K.?ürm?ssy 《The European Physical Journal A - Hadrons and Nuclei》2009,40(3):325-340
We review the idea of generating non-extensive stationary distributions based on aaabstract composition rules of the subsystem
energies, in particular the parton cascade method, using a Boltzmann equation with relativistic kinematics and modified two-body
energy composition rules. The thermodynamical behavior of such model systems is investigated. As an application hadronic spectra
with power law tails are analyzed in the framework of a quark coalescence model.
This paper is part of the Topical Issue Statistical Power Law Tails in High-Energy Phenomena. 相似文献
19.
Alexander Perjssy Du
an Loos Erkki Kolehmainen Pavol Hrn
iar 《Journal of organometallic chemistry》1999,590(2):1-264
The IR, 13C- and 17O-NMR spectral characteristics of the Cr(CO)3 group in a series of eight chromium, tricarbonyl[3-[(η6-aryl)methylene]-Z-1(3H)-isobenzofuranones] were correlated mutually as well as with theoretical data obtained by optimized MMX force-field and EHT calculations. The net charges on the carbon and oxygen atoms of the CO group and their differences were found as the most appropriate quantitative characteristics for the electronic properties of the Cr(CO)3 group. Using the results of the previously reported linear correlations, the electron-withdrawing effect of the PhCr(CO)3 moiety, weakened by the back-donation effect, was estimated as σ0.45 on the scale of Hammett substituent constants. 相似文献
20.
Mössbauer investigations were carried out on low carbon steels containing 12–13.5% Cr and 3–5% Ni in order to get information about the reason of cracking and fracture which take place during the use of turbine blade wheels. The quantity of retained austenite determined from the Mössbauer spectra of steels was low (<1%) in the cracked and fractured basic materials. Comparing this value with those being considerable in quenched (≈11%) as well as in annealed state (≈5%) of the same sample, we can conclude that the transformation of the austenite taking place during the working of turbine blade wheel can be associated with the cracking and the fracture. We found an anomalous increase of the quantity of the austenite in steel samples (quenched from different temperature between 700 and 1000 °C and aged at 450–600 °C) aged again at 450–550 °C. On the basis of the evaluation of Mössbauer spectra of the steels, information can be obtained about the changes in the concentration of alloying elements being in martensite at the various heat treatments. 相似文献