A vertex coloring of a graph G is an assignment of colors to the vertices of G so that every two adjacent vertices of G have different colors. A coloring related property of a graphs is also an assignment of colors or labels to the vertices of a graph, in which the process of labeling is done according to an extra condition. A set S of vertices of a graph G is a dominating set in G if every vertex outside of S is adjacent to at least one vertex belonging to S. A domination parameter of G is related to those structures of a graph that satisfy some domination property together with other conditions on the vertices of G. In this article we study several mathematical properties related to coloring, domination and location of corona graphs. We investigate the distance-k colorings of corona graphs. Particularly, we obtain tight bounds for the distance-2 chromatic number and distance-3 chromatic number of corona graphs, through some relationships between the distance-k chromatic number of corona graphs and the distance-k chromatic number of its factors. Moreover, we give the exact value of the distance-k chromatic number of the corona of a path and an arbitrary graph. On the other hand, we obtain bounds for the Roman dominating number and the locating–domination number of corona graphs. We give closed formulaes for the k-domination number, the distance-k domination number, the independence domination number, the domatic number and the idomatic number of corona graphs. 相似文献
Accreditation and Quality Assurance - Enabling the possibility of “tracing” the route of a food product is a legal requirement for all participants of the food chain. It allows... 相似文献
This paper describes a miniaturized multisensor platform (MP-ISES) consisting of electrodes: a reference one (RE) and ion-selective electrodes (ISEs) for monitoring Na+, K+, Ca2+, Mg2+, Cl−, and SCN− ions and pH in human saliva. Gold electrode surface was modified by deposition of two layers: electrosynthesized PEDOT:PSS forming an intermediate layer, and ion-selective membrane. The developed ISEs were characterized by a wide linear range and sensitivity consistent with the Nernst model. The entire MP-ISEs are characterized by satisfactory metrological parameters demonstrating their applicability in biomedical research, in particular in measurements concerning determination of ionic profiles of saliva. Saliva samples of 18 volunteers aged from 20 to 26 participating in a month experiment had been daily collected and investigated using the MP-ISEs assigned individually to each person. Personalized profiles of ions (ionograms) in saliva, such as Na+, K+, Ca2+, Mg2+, Cl−, SCN−, and H+, were obtained.
The properties of both Cu2+ and Cu+ ions in zeolite CuY were followed with NO and CO as probe molecules. Cu2+ was found to be located in SII, SII*, and SIII sites, whereas Cu+ was found in SII and SII* sites. The fine analysis of the spectra of Cu2+-NO and Cu+-CO adducts suggests that both in SII and in SII* sites two kinds of Cu cations exist. They differ in the positive charge, which may be related to the varying numbers of AlO4− in close proximity. The experiments of NO and CO adsorption and desorption evidenced that both Cu2+ and Cu+ sites of highest positive charge bind probe molecules most strongly but activate them to a lesser extent than the Cu sites of lowest positive charge. The experiments of reduction with hydrogen evidenced that the Cu ions of higher positive charge are first reduced by hydrogen. On the other hand, Cu sites of the lowest positive charge are first oxidized by oxygen. The experiments with CuNaY zeolites of various Cu contents suggest that the first introduced Cu (at low Cu contents) created Cu+, which was the most neutralized by framework oxygens. Such Cu cations are the most stabilized by framework oxygens. 相似文献
Despite many advances in therapy, glioblastoma (GB) is still characterized by its poor prognosis. The main reason for this is unsuccessful treatment, which slightly extends the duration of remission; thus, new regimens are needed. One of many types of chemotherapeutics that are being investigated in this field is topoisomerase inhibitors, mainly in combination therapy with other drugs. On the other hand, the search for new anti-cancer substances continues. Neobavaisoflavone (NBIF) is a natural compound isolated from Psoralea corylifolia L., which possesses anti-oxidant, anti-inflammatory, and anti-cancer properties. The aim of this study was to evaluate the effect of NBIF in human U-87 MG glioblastoma cells in comparison to normal human NHA astrocytes, and to examine if it influences the activity of irinotecan, etoposide, and doxorubicin in this in vitro model. We demonstrated that NBIF decreases U-87 MG cells viability in a dose-dependent manner. Furthermore, we found that it inhibits cell growth and causes glutathione (GSH) depletion more intensely in U-87 MG cells than in astrocytes. This study also provides, for the first time, evidence of the potentialization of the doxorubicin effect by NBIF, which was shown by the reduction in the viability in U-87 MG cells. 相似文献
An efficient, versatile, enantioselective synthesis of 1,3-disubstituted and 1,3,6-trisubstituted 5-methylidenedihydrouracils applying Horner-Wadsworth Emmons methodology was developed. Starting 1,3-disubstituted 5-diethoxyphosphoryluracils were subjected to reduction of the double bond or addition of various Grignard reagents and obtained Horner-Wadsworth Emmons reagents were used for the olefination of formaldehyde. Enantioselective synthesis of 1,3,6-trisubstituted 5-methylidenedihydrouracils was accomplished by introducing (R,R)- or (S,S)-di(1-phenylethylamino)phosphoryl groups as chiral auxiliary. Additions of Grignard reagents in the presence of these groups were highly and complimentary diastereoselective (de?~?80%). Further separation of the diastereomeric mixtures by column chromatography enabled synthesis of (R)- and (S)-1,3,6-trisubstituted-5-methylidenedihydrouracils with ee?≥?98%. Furthermore, absolute configuration of the adducts and final products was established using single crystal X-ray analysis. Stereochemical course of the addition reactions is also discussed. 相似文献
A large-scale synthesis of known Ru olefin metathesis catalyst VII featuring an unsymmetrical N-heterocyclic carbene (NHC) ligand with one 2,5-diisopropylphenyl (DIPP) and one thiophenylmethylene N-substituent is reported. The optimised procedure does not require column chromatography in any step and allows for preparation of up to 0.5 kg batches of the catalyst from simple precursors. The application profile of the obtained catalyst was studied in environmentally friendly dimethyl carbonate (DMC). Although VII exhibited low efficiency in cross-metathesis (CM) with electron-deficient partners, good to excellent results were noted for substrates featuring easy to isomerise C−C double bonds. This includes polyfunctional substrates of medicinal chemistry interest, such as analogues of psychoactive 5F-PB-22 and NM-2201 and two PDE5 inhibitors—Sildenafil and Vardenafil. Finally, a larger scale ring-closing metathesis (RCM) of a Vardenafil derivative was conducted in DMC, allowing for straightforward isolation of the expected product (23 g) in high yield and with low Ru contamination level (7.7 ppm). 相似文献
The main goal of the present density functional theory calculations is a comparative study of NO, O2, ${{\rm NO}_{2}^{-}}$ , and H2O binding to different forms of cob(II)alamins and cob(III)alamins. The comparison of binding energies of small ligands enables one to draw conclusions regarding the stability of the studied derivatives of cobalamins as well as to define the preferred form of cobalamin for each ligand. Ligands such as NO and O2 favor cob(II)alamins, while H2O and ${{\rm NO}_{2}^{-}}$ cob(III)alamins. The obtained results are confronted with available experimental data. Finally, our findings allow one to divide the studied small ligands into two groups: NO and O2 for which the coordination to cobalamins significantly weakens their internal bonds, and ${{\rm NO}_{2}^{-}}$ and H2O for which the effect is not observed. 相似文献