Alkalimetalle

Ohne Zusammenfassung     

Lower bounds for the energy of digraphs

The energy of a digraph D is defined as , where z₁,…,z_n are the eigenvalues of D. In this article we find lower bounds for the energy of digraphs in terms of the number of closed walks of length 2, extending in this way the result obtained by Caporossi et al. [G. Caporossi, D. Cvetkovi?, I. Gutman, P. Hansen, Variable neighborhood search for extremal graphs. 2. Finding graphs with extremal energy, J. Chem. Inf. Comput. Sci. 39 (1999) 984-996]: for all graphs G with m edges. Also, we study digraphs with three eigenvalues.     

Novel photosensitive properties of gadolinium–lead germanate glasses

Glasses of the system xGd₂O₃ · (100 ? x)[7GeO₂ · 3PbO] with 0 ≤ x ≤ 40 mol% were prepared using the melt quenching method. Lead germanate glasses are particularly interesting in the context of the germanate anomaly. In this paper, we investigate changes in the coordination number of germanium in gadolinium–lead germanate glasses using molar volume analysis, density measurements, FTIR and UV–VIS spectroscopy, and density functional theory (DFT). Despite some inconsistencies, the coordination change model remains the currently accepted model for the anomalous behaviour of lead germanate glasses. Based on these experimental results, we propose the following mechanism for the germanate anomaly. (i) The low thermodynamic stability of the [GeO₆] structural unit and the occupation of interstices of larger dimensions (the six-coordinated interstices of the [PbO₆] structural units) in the lead germanate network yield [GeO₅] structural units with higher thermodynamic stability and larger ionic radii. (ii) Not linked to the terminal oxygens of the [GeO₅] structural units and with the formation of smaller network cavities of the lead germanate glass, links are required with [GeO₄] tetrahedra for stabilization, generating the formation of three-membered rings of [GeO₄] tetrahedral structural units.     

CXCL10 blockade protects mice from cyclophosphamide-induced cystitis

Background  

Alterations in serum CXCR3 ligand levels were examined in interstitial cystitis (IC) patients; similar expression patterns in serum as well as CXCR3, CXCR3 ligands, and cytokines expressed by peripheral and local leukocyte subpopulations were characterized during cyclophosphamide (CYP)-induced acute cystitis in mice.     

GC‐FID determination and pharmacokinetic studies of oleanolic acid in human serum

Analytical interest of OA determination in human serum has increased owing to the increasing interest in pharmaceutical research by pharmaceutical properties. A simple, specific, precise and accurate GC method with flame ionization detector (FID) developed and validated for the determination of oleanolic acid (OA) in human serum (HS). To an aliquot of HS, internal standard was added and a combination of liquid–liquid extraction with a mixture of diethyl ether‐isopropyl alcohol, filtration and consecutive GC resulted in separation and quantification of OA. The organic phase was analyzed using a GC system equipped with a 30 × 0.25 mm i.d. Rtx‐65TG capillary column and FID detection. Total chromatographic time was 10 min and no interfering peaks from endogenous components in blank serum were observed. The OA/internal standard peak area ratio was linearly fitted to the OA concentration (r = 0.992) over the range 10–1500 ng/mL. The mean serum extraction recovery of OA was 96.7 ± 1.0% and the lower limit of quantification based on 5 mL of serum was 10.7 ng/mL. The intra‐day coefficient of variation ranged from 1.3 to 3.6% and inter‐day varied from 1.4 to 4.5%. The developed method was used to study the pharmacokinetics of OA after oral administration in humans. The assay was simple, sensitive, precise and accurate for the use in the study of the mechanisms of absorption and distribution of OA in humans. Copyright © 2015 John Wiley & Sons, Ltd.     

Relationships between structure, retention and biological activity of some Schiff base ligands and their complexes

The lipophilicity of a series of Schiff base ligands and their complexes with nickel(II) and copper(II) has been determined by reversed-phase thin-layer chromatography using binary dioxane-water mobile phase. Chelate ligands were prepared by condensation of diamine and the corresponding beta-diketone. Copper(II) and nickel(II) complexes with chelate ligands containing ethane-1,2-diamine or propane-1,2-diamine as the amine part and pentane-2,4-dione and/or 1-phenylbutane-1,3-dione, pentane-2,4-dione and/or 1,1,1-trifluoropentane-2,4-dione, or 1,1,1-trifluoropentane-2,4-dione and/or 1-phenylbutane-1,3-dione as the beta-diketone part were synthesized. Some of investigated compounds were screened for their in vitro antifungal activity against Sacharomyces cerevisiae and antibacterial activity against Escherichia coli. Chromatographically obtained lipophilicity parameters were correlated both with calculated n-octanol-water partition coefficient C log P and antimicrobial activities. Satisfactory correlations were obtained. Chromatographic data proved to be reliable parameters for describing the lipophilic properties of the investigated compounds. Additionally, the principal components analysis was performed on the data chromatographically obtained. This statistical method was useful for distinguishing compounds and objective comparison of their lipophilicity parameters.     

Surface tension modelling of liquid Cd–Sn–Zn alloys

The thermodynamic model in conjunction with Butler equation and the geometric models were used for the surface tension calculation of Cd–Sn–Zn liquid alloys. Good agreement was found between the experimental data for limiting binaries and model calculations performed with Butler model. In the case of ternary alloys, the surface tension variation with Cd content is better reproduced in the case of alloys lying on vertical sections defined by high Sn to Zn molar fraction ratio. The calculated surface tension is in relatively good agreement with the available experimental data. In addition, the surface segregation of liquid ternary Cd–Sn–Zn and constituent binaries has also been calculated.     

Electrochemical behavior and antioxidant activity of tetradentate Schiff bases and their copper(II) complexes

This study describes the effects of the substituents on electrochemical behavior and antioxidant activity of the six tetradentate Schiff bases, containing ethane-1,2-diamine or propane-1,2-diamine as the amine part and pentane-2,4-dione and/or 1-phenylbutane-1,3-dione as ??-diketone, and corresponding copper(II) complexes. Cyclic voltammograms of these compounds were recorded in dimethylsulfoxide and 0.1?M sodium perchlorate as supporting electrolyte with glassy carbon as working electrode at different scan rates. The voltammograms of Schiff bases alone showed only one irreversible peak. Voltammograms recorded for complexes showed the presence of quasi-reversible processes taking place at the metal center and reversible process at the ligand part. Both steric and inductive effects of substituents and structure of imine bridge of Schiff base ligands as well as complexes were discussed. These effects appear relevant for the antioxidant activity. Antioxidant activity of the investigated compounds expressed as Trolox equivalent antioxidant capacity is also discussed. The electrochemical behavior showed a high correlation with the antioxidant activity for investigated compounds.     

In vitro inhibitory activity of essential oil vapors against Ascosphaera apis

This work evaluates the in vitro inhibitory activity of 70 essential oils (EOs) in the vapor phase for the control of Chalkbrood disease caused by Ascosphaera apis Maassen ex Claussen (Olive et Spiltoir). Two wild strains isolated from infected honey bee colonies together with one standard collection strain were tested by the microatmosphere method. From 70 EOs, 39 exhibited an antifungal effect against A. apis standard and wild strains. The greatest antifungal action was observed for EO vapors from Armoracia rusticana, followed by Thymus vulgaris, Cymbopogon flexosus, Origanum vulgare and Allium sativum. An investigation of chemical composition by GC-MS revealed, that the most active EOs contained allyl isothiocyanate, citral, carvacrol and diallyl sulfides as the main constituents. The chemical composition plays a key role, as activities of different EOs from the same botanical species were different according to their composition.