Restrained Domination in Claw-Free Graphs with Minimum Degree at Least Two

Let G = (V, E) be a graph. A set \({S\subseteq V}\) is a restrained dominating set if every vertex in V ? S is adjacent to a vertex in S and to a vertex in V ? S. The restrained domination number of G, denoted γ _r (G), is the smallest cardinality of a restrained dominating set of G. We will show that if G is claw-free with minimum degree at least two and \({G\notin \{C_{4},C_{5},C_{7},C_{8},C_{11},C_{14},C_{17}\}}\) , then \({\gamma_{r}(G)\leq \frac{2n}{5}.}\)     

Blood Compatibility of Multilayered Polyelectrolyte Films Containing Immobilized Gold Nanoparticles

Surface material functionalization including layer‐by‐layer (LbL) polyelectrolyte films with incorporated nanoparticles is a growing field with a wide range of biomedical applications: drug reservoirs, medical devices, or tissue engineering. In parallel, gold nanoparticles (AuNPs) can be grafted by drugs and sensitive molecules using simple protocols. This study shows that AuNP behavior is modified when they are entrapped into three partner LbL films in comparison to the colloidal solution. A polycationic (polyallylamine hydrochloride (PAH)) and a polyanionic (polyacrylic acid (PAA)) polymer is used to build films based on three cycles ((PAH/AuNP/PAA)₃). To investigate the interaction with biomolecules and cells, three different films are developed changing the outer layer (either PAH or AuNP or PAA) with the same number of AuNP deposit. The best biocompatibility is observed with a polyacrylic acid outer layer. Due to the high capacity of drug grafting on gold nanoparticles, the results seem promising for the development of nanostructured biomedical devices.     

Mild, base-free copper-catalyzed N-arylations of heterocycles using potassium aryltrifluoroborates in water under air

An economic, mild and efficient copper-catalyzed methodology for the N-arylation of heterocycles was optimized using potassium aryltrifluoroborates in water.     

Upconversion luminescence dynamics of Er-doped fluoride crystals for optical converters

Erbium (Er)-doped fluoride crystals (YLF, BYF, CaF₂, etc.) are well-known as active media for solid-state lasers emitting in IR and VIS spectral domains, and as materials for efficient near-IR to VIS upconversion. In this paper, we report on the study of conversion of IR light from an ～1.5 μm spectral region to an ～1 μm spectral domain in low-phonon RE-doped fluoride crystals CaF₂ (RE=Er³⁺ Yb³⁺). Energy transfer processes taking place at selective pulsed and CW laser excitation are investigated experimentally. It is shown that in the CaF₂:RE crystals efficient conversion of IR radiation from the ～1.5 μm region to the ～1 μm region occurs, and these crystals are perspective for using in spectral converters for enhancing solar cell efficiency.     

Relation entre structure et conductivite ionique basse temperature de Ag3PO4

The ionic conductivity of Ag₃PO₄ versus the temperature was determined. The cristal structure was reinvestigated at different temperatures (170 K, 290 K and 570 K) showing a normal increase of the unit cell with the temperature but a contraction of PO₄ tetraedra. This leads to Ag-0 bonds somewhat looser and too more space for the Ag⁺ cation to move.     

Flow-injection determination of nitrate in natural waters with copper- and copperised cadmium tubes in the reaction manifold system

Summary An automated method for the determination of nitrate-nitrogen in surface, ground and domestic water based on flow-injection spectrophotometry is described. Nitrate is reduced to nitrite with a copperised cadmium tube in the reaction manifold. Nitrite is diazotised with sulphanilamide and the product is coupled with N-(1-naphthyl)ethylenediammonium dichloride to form a highly coloured azo dye, which is measured at 520 nm. A copper tube, incorporated into the reaction manifold before the copperised cadmium tube not only improves accuracy in the long run, but also extended the lifetime of the copperised cadmium tube. The sampling rate is 50 samples per hour. The method is suitable for the determination of nitrate-nitrogen with a coefficient of variation of better than 1.5%.

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Fließinjektionsbestimmung von Nitrat in natürlichen Wässern mit Hilfe von Cu- und Cu/Cd-Röhren im Reaktionssystem

Zusammenfassung Ein automatisiertes Verfahren zur Bestimmung von Nitrat-Stickstoff in Oberflächen-, Grund- und Leitungswasser mit Hilfe der Fließinjektions-Spektral-photometrie wird beschrieben. Dabei wird Nitrat im Reaktionssystem in einer verkupferten Cadmiumröhre zu Nitrit reduziert; das Nitrit wird mit Sulfanilamid diazotiert und mit N-(1-Naphthyl)-ethylendiammoniumdichlorid zu einem intensiv gefärbten Azofarbstoff gekoppelt, der bei 520 nm gemessen wird. Eine Kupferröhre, die vor die verkupferte Cadmiumröhre im Reaktionssystem geschaltet wird, verbessert die Genauigkeit und verlängert die Lebensdauer der Cu/ Cd-Röhre. Je Stunde werden 50 Proben verarbeitet. Das Verfahren ist zur Nitratstickstoff-Bestimmung mit einem Variationskoeffizienten besser als 1,5% geeignet.

     

Uniqueness of the iterative solution of the optimized effective potential equation

The optimized effective potential (OEP) equation can be used in a numerically efficient self-consistent form to solve for the density functional exchange and correlation potentials, as shown in a recent paper of Kummel and Perdew [Phys. Rev. Lett. 90, 43004 (2003)]. The uniqueness of an iterative solution of the OEP equation has not yet been adequately addressed. In this paper, it is shown that no nonconstant multiplicative potentials that can contaminate an iterative solution of the OEP equation exist and, hence, that formally the exact exchange-correlation potential determined form of the OEP equation is unique to within a constant.