Sequences,claws and cyclability of graphs

A subset S of vertices of a graph G is called cyclable in G if there is in G some cycle containing all the vertices of S. We give two results on the cyclability of a vertex subset in graphs, one of which is related to “hamiltonian-nice-sequence” conditions and the other of which is related to “claw-free” conditions. They imply many known results on hamiltonian graph theory. Moreover, the analogous results related to the hamilton-connectivity or to the existence of dominating cycle are also given. © 1996 John Wiley & Sons, Inc.     

The Soave,Twu and Boston–Mathias alpha functions in cubic equations of state. Part II. Modeling of thermodynamic properties of pure compounds

Cubic equations of state (EoS) are commonly used for industrial applications, due to their simplicity in predicting pure compound and mixture thermodynamic properties in vapor and liquid phases. The accuracy of their predictions mainly depends on the choice of the attractive term a(T) and numerous models were developed in literature for this purpose. Among them, the Soave and the Twu models have acquired a wide popularity, as well as the Boston–Mathias model commonly used for supercritical applications. However, most of the works concerned with the comparison of literature attractive terms only focuses on the representation of pure component saturation properties. In particular, the analysis of the respective influence of the EoS and the first and second derivatives of the alpha function on the modeling of enthalpies and heat capacities with respect to temperature and pressure, especially in the supercritical range, was never reported in literature. This is precisely the purpose of the present study.     

Investigating cellular signaling reactions in single attoliter vesicles

Understanding cellular signaling mediated by cell surface receptors is key to modern biomedical research and drug development. The discovery of a growing number of potential molecular targets and therapeutic compounds requires downscaling and accelerated functional screening. Receptor-mediated cellular responses are typically investigated on single cells or cell populations. Here, we show how to monitor cellular signaling reactions at a yet unreached miniaturization level. On the basis of our observations, cytochalasin induces mammalian cells to extrude from their plasma membrane submicrometer-sized native vesicles. They comprise functional cell surface receptors correctly exposing their extracellular ligand binding sites on the outer vesicle surface and retaining cytosolic proteins in the vesicle interior. As a prototypical example, ligand binding to the ionotropic 5-HT(3) receptor and subsequent transmembrane Ca(2+) signaling were monitored in single attoliter vesicles. Thus, native vesicles are the smallest autonomous containers capable of performing cellular signaling reactions under physiological conditions. Because a single cell delivers about 50 native vesicles, which can be isolated and addressed as individuals, our concept allows multiple functional analyses of individual cells having a limited availability and opens new vistas for miniaturized bioanalytics.     

Determination of 226Ra in solid samples of few milligrams after mineralisation and measurement by solid scintillation

A protocol is proposed for the measurement of ²²⁶Ra on 150 mg of solid sample without radiochemistry. To evaluate the performance of this method, standard samples were used and the results were in good agreement with reference values. The detection limit obtained is about 130 Bq kg⁻¹ (dry weight) without mineralised solution concentration by evaporation. A concentration of the solution by 4 and/or an increase of sample mass by 4 in the case of microwave digestion system, allows achieving a detection limit of 30 Bq kg⁻¹ (dry weight) and thus measuring ²²⁶Ra in most soils. This method could also be used for NORM sites on soil and sediment samples.

     

Neighborhood unions and extremal spanning trees

We generalize a known sufficient condition for the traceability of a graph to a condition for the existence of a spanning tree with a bounded number of leaves. Both of the conditions involve neighborhood unions. Further, we present two results on spanning spiders (trees with a single branching vertex). We pose a number of open questions concerning extremal spanning trees.     

One-pot synthesis of 1-hydroxymethylene-1,1-bisphosphonate partial esters

A selective one-pot procedure of synthesis of 1-hydroxymethylene-1,1-bisphosphonic partial trimethylesters and P,P-, P,P′-diesters was described.