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1.
Martín-Matute B Bogár K Edin M Kaynak FB Bäckvall JE 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(20):5832-5842
A range of ruthenium cyclopentadienyl (Cp) complexes have been prepared and used for isomerization of allylic alcohols to the corresponding saturated carbonyl compounds. Complexes bearing CO ligands show higher activity than those with PPh3 ligands. The isomerization rate is highly affected by the substituents on the Cp ring. Tetra(phenyl)methyl-substituted catalysts rapidly isomerize allylic alcohols under very mild reaction conditions (ambient temperature) with short reaction times. Substituted allylic alcohols have been isomerized by employing Ru-Cp complexes. A study of the isomerization catalyzed by [Ru(Ph5Cp)(CO)2H] (14) indicates that the isomerization catalyzed by ruthenium hydrides partly follows a different mechanism than that of ruthenium halides activated by KOtBu. Furthermore, the lack of ketone exchange when the isomerization was performed in the presence of an unsaturated ketone (1 equiv), different from that obtained by dehydrogenation of the starting allylic alcohol, supports a mechanism in which the isomerization takes place within the coordination sphere of the ruthenium catalyst. 相似文献
2.
Turan Ozturk Andrey S. Klymchenko Sule Oncul Sule Taskiran F. Betul Kaynak Alexander P. Demchenko 《Tetrahedron》2007,63(41):10290-10299
Nine new 3-hydroxyflavone derivatives as fluorescent molecular sensors having two well-separated emission bands were synthesized. These sensors can occupy well-determined locations and orientations in macromolecular ensembles, such as micelles due to their finely-tuned designs. These polarity-sensitive dyes can incorporate into the anhydrous hydrophobic core of aqueous micelles. 相似文献
3.
We show that the ground state energy is bounded from below when there are infinitely many attractive delta function potentials placed in arbitrary locations, while all being separated at least by a minimum distance, on two dimensional non-compact manifold. To facilitate the reading of the paper, we first present the arguments in the setting of Cartan–Hadamard manifolds and then subsequently discuss the general case. For this purpose, we employ the heat kernel techniques as well as some comparison theorems of Riemannian geometry, thus generalizing the arguments in the flat case following the approach presented in Albeverio et al. (2004). 相似文献
4.
Ayşegül Kahraman Gökay Kaynak Gizem Akkaya Orhan Gürler Sezai Yalçın 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):1057-1066
Activity concentrations of gross-β, naturally occurring 226Ra, 232Th, 210Pb, 7Be and anthropogenic 137Cs in epiphytic lichens collected from Uluda? Mountain are presented and discussed with the aim of evaluating potential usability of lichens as a biomonitor. The activity concentrations of gross-β, 137Cs, 40K, 226Ra, 232Th, 210Pb and 7Be in the lichen samples were found to be in the range of 177–707, 4.05–94.26, 86–211, below detection limit (BDL)—19.2, BDL—14.0, 229–872, and 72.1–220.7 Bq kg?1 in dry weight, respectively. 137Cs content in collected epiphytic lichens was in descending order: Parmelia sulcata > Lobaria pulmonaria > Pseudevernia furfuracea > Usnea filipendula. The best biomonitor for 137Cs among the lichen species used in this study was determined as Parmelia sulcata. Pearson’s correlation coefficient was calculated between 137Cs and 40K activity concentrations using a statistical package program (SPSS ver. 17.0) and a negative correlation value (R = ?0,323, p = 0,222) was obtained. The highest 226Ra and 232Th activity concentrations were found in Bo?azova Yaylas? which has a geological structure including granitic rocks. It was found that 137Cs and 7Be activity concentrations in species demonstrated an inverse behaviour. The effect of mean annual precipitation and temperature on 7Be activity concentration was determined using multi regression analysis. Also, correlations between the 137Cs and 7Be, and 40K and 7Be were investigated. 相似文献
5.
JPC – Journal of Planar Chromatography – Modern TLC - A thin-layer chromatographic method with densitometric UV detection at 286 nm after ethyl acetate extraction is described for... 相似文献
6.
F. Betül Kaynak Süheyla
zbey Turan
ztürk Erdal Erta 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1125-1126
The title compound, C17H10S4, has two independent molecules in the asymmetric unit. In both molecules, the fused heterocycle is almost planar and the phenyl groups make dihedral angles of 42.88 (9) and 52.79 (8)° with the fused heterocycle in one molecule, and angles of 40.62 (9) and 52.28 (8)° in the other. The crystal packing is governed by short intermolecular S?S interactions, the shortest contact being 3.333 (1) Å. 相似文献
7.
Yalcin S Gurler O Akar UT Incirci F Kaynak G Gundogdu O 《Isotopes in environmental and health studies》2011,47(4):438-445
Concentration of (222)Rn was determined in selected natural spring and tap water samples collected during spring and summer seasons from Kastamonu, Turkey. The aim of this work was to produce a map of the radon concentrations in water sources of the province and to determine any potential radiological risk for the local population. Radon measurements were performed by an AlphaGUARD radon gas analyser. The average radon concentrations were found to vary from 0.39±0.02 to 12.73±0.39?Bq?l(-1) for natural springs and from 0.36±0.04 to 9.29±0.45?Bq?l(-1) for tap water in spring, from 0.50±0.09 to 19.21±1.00?Bq?l(-1) for natural springs and from 0.31±0.03 to 13.14±0.38?Bq?l(-1) for tap water in summer. Furthermore, the results are compared with international recommendations and concentrations reported for other countries. Doses resulting from the consumption of these waters were calculated. The effective dose equivalents due to the intake of the (222)Rn present in these waters are expected to range from 0.93 to 32.54?μSv?y(-1) in summer and from 0.80 to 49.09?μSv?y(-1) in spring. 相似文献
8.
Nihat Ali IsitmanCevdet Kaynak 《Polymer Degradation and Stability》2011,96(12):2284-2289
This study describes the mechanism of flammability reduction in flame-retarded polymer matrix organo-montmorillonite reinforced nanocomposites. Morphologies of untested polymer nanocomposites and char residues formed by combustion in the mass loss calorimeter are characterized by XRD and TEM techniques. It is postulated that a combination of well-dispersed montmorillonite platelets and flame retardants in the polymer matrix provides nano-structured char formation. Initial montmorillonite dispersion in flame-retarded nanocomposites is found to be a major controlling factor on formed char nanostructures. An initially intercalated structure is invariantly converted to complete montmorillonite collapse whereas an initially exfoliated structure transforms to nano-structured chars demonstrating retained exfoliation or a new state of intercalation via incomplete collapse of montmorillonite layers. It is proposed that nano-structured char formation is the effective mechanism of flammability reduction, i.e. reduction in rate of heat release during combustion, in flame-retarded polymer nanocomposites. 相似文献
9.
Sezai Yalcin Orhan Gurler Urkiye Tarim Akar Fulya Incirci Gokay Kaynak Ozcan Gundogdu 《Isotopes in environmental and health studies》2013,49(4):438-445
Concentration of 222Rn was determined in selected natural spring and tap water samples collected during spring and summer seasons from Kastamonu, Turkey. The aim of this work was to produce a map of the radon concentrations in water sources of the province and to determine any potential radiological risk for the local population. Radon measurements were performed by an AlphaGUARD radon gas analyser. The average radon concentrations were found to vary from 0.39±0.02 to 12.73±0.39 Bq l?1 for natural springs and from 0.36±0.04 to 9.29±0.45 Bq l?1 for tap water in spring, from 0.50±0.09 to 19.21±1.00 Bq l?1 for natural springs and from 0.31±0.03 to 13.14±0.38 Bq l?1 for tap water in summer. Furthermore, the results are compared with international recommendations and concentrations reported for other countries. Doses resulting from the consumption of these waters were calculated. The effective dose equivalents due to the intake of the 222Rn present in these waters are expected to range from 0.93 to 32.54 μSv y?1 in summer and from 0.80 to 49.09 μSv y?1 in spring. 相似文献
10.
Photoelectric absorption is an interaction in which an incoming gamma ray virtually transfers all of its energy to an atomic electron, usually the most tightly bound K-shell electron of an atom. This paper uses the Win XCOM computer code as a reference base. We found analytical photoelectric attenuation coefficients for researchers using the Monte Carlo simulation program for Z∈ [1; 100] and E∈[10 keV; 3 MeV]. We define a photoelectric effect operator and coefficient operators and a series for photoelectric absorption. We have calculated two polynomial coefficient operators for use with XCOM for photoelectric absorption. We determined 14 energies and atomic number limits for elements, and we find that they are accurate limits of photoelectric absorption for fitting with XCOM. 相似文献