Development of a generic assay for the determination of total trihydroxybenzoate derivatives based on gold-luminol chemiluminescence

A selective assay for the determination of one of the most important class of phenolic compounds, namely trihydroxybenzoates (monomeric and polymeric compounds having at least one gallate moiety) based on their enhancing effect on the chemiluminogenic reaction between gold ions and luminol is described for the first time. In the presence of trihydroxybenzoate derivatives, the light emission generated when alkaline luminol is oxidized by gold ions is amplified several orders of magnitude compared to other common phenolic compounds which exhibit minor reactivity or no reactivity at all (e.g. hydroxycinnamates, flavonols, benzenediols). Based on this property, the experimental conditions were optimized in order to enable the determination of total trihydroxybenzoates in complex mixtures without resorting to separation techniques. The method was applied to samples of different composition (teas, herbal infusions and wines) with satisfactory analytical features yielding detection limits at the 10⁻⁷ mol L⁻¹ level, intra-day precision of 3.1%, inter-day precision less than 10% and recoveries between 88.7 and 97.6%. The strengths and weaknesses of the method were identified and discussed in relation to its application in real samples.     

Control of the water adhesion on hydrophobic micropillars by spray coating technique

We present an alternative approach for controlling the water adhesion on solid superhydrophobic surfaces by varying their coverage with a spray coating technique. In particular, micro-, submicro-, and nanorough surfaces were developed starting from photolithographically tailored SU-8 micropillars that were used as substrates for spraying first poly(tetrafluoroethylene) submicrometer particles and subsequently iron oxide nanoparticles. The sprayed particles serve to induce surface submicrometer and nanoscale roughness, rendering the SU-8 patterns superhydrophobic (apparent contact angle values of more than 150°), and also to tune the water adhesion between extreme states, turning the surfaces from “non-sticky” to “sticky” while preserving their superhydrophobicity. The influence of the chemical properties and of the geometrical characteristics of the functionalized surfaces on the wetting properties is discussed within the frame of the theory. This simple method can find various applications in the fabrication of microfluidic devices, smart surfaces, and biotechnological and antifouling materials.     

Chemoselective protection of solid-phase compatible Fmoc-phosphinic building blocks

An efficient four-step synthetic strategy able to fully discriminate hydroxyphosphinyl and carboxylic groups of Fmoc-phosphinic building blocks and related analogues has been developed. The proposed method applies selective acidic removal of the phenacyl (Pac) group from the hydroxyphosphinyl functionality and protection by the 1-adamantyl (Ad) group. Reductive removal of the Pac group from the carboxylic functionality leads to Fmoc-protected phosphinic pseudodipeptidic units suitable for phosphinic peptide and library development using solid-phase peptide synthesis (SPPS).     

Synthesis of oxadiazoloquinoxaline,oxathiadiazoloquinoxaline and oxadiazolobenzothiazine derivatives

Bis‐amidoxime 1 reacts with phosgene, thiophosgene and thionylchloride to give the corresponding bisfused oxadiazolo‐ and oxathiadiazoloquinoxalines 2, 4, 5 along with the unexpected furazano‐derivative 3 , while monoamidoximes 9, 13 by treatment with ethyl chloroformate affords the oxadiazoloquinoxaline and the oxadiazolobenzothiazine derivatives 14, 15 along with the dicarboxylated product 16 .     

Systematic synthesis of heterometallic Ni/Fe/S and Cu/Fe/S clusters with a pentlandite-like M8S6 core

The systematic synthesis of heterometallic Ni/Fe/S and Cu/Fe/S clusters with a M8S6 core structure that resembles that of pentlandite minerals is described. The chemical properties and electronic structures of the new clusters have been investigated and are reported in this communication.     

Regularity of the density of states in the Anderson model on a strip for potentials with singular continuous distributions

We derive regularity properties for the density of states in the Anderson model on a one-dimensional strip for potentials with singular continuous distributions. For example, if the characteristic function is infinitely differentiable with bounded derivatives and together with all its derivatives goes to zero at infinity, we show that the density of states is infinitely differentiable.     

A quasiconcave minimization method for solving linear two-level programs

In this paper the linear two-level problem is considered. The problem is reformulated to an equivalent quasiconcave minimization problem, via a reverse convex transformation. A branch and bound algorithm is developed which takes the specific structure into account and combines an outer approximation technique with a subdivision procedure.     

Weak disorder expansions for the Anderson Model on a one dimensional strip at the center of the band

We study the asymptotic behavior of the averaged diagonal matrix elements of the Greens kernel for the Anderson Model on a one-dimensional strip and for a set of special energies close to the center of the band.     

Editorial: Hierarchical and bilevel programming

Approximately twenty years ago the modern interest for hierarchical programming was initiated by J. Bracken and J.M. McGill [9], [10]. The activities in the field have ever grown lively, both in terms of theoretical developments and terms of the diversity of the applications. The collection of seven papers in this issue covers a diverse number of topics and provides a good picture of recent research activities in the field of bilevel and hierarchical programming. The papers can be roughly divided into three categories; Linear bilevel programming is addressed in the first two papers by Gendreau et al and Moshirvaziri et al; The following three papers by Nicholls, Loridan & Morgan, and Kalashnikov & Kalashnikova are concerned with nonlinear bilevel programming; and, finally, Wen & Lin and Nagase & Aiyoshi address hierarchical decision making issues relating to both biobjective and bilevel programming.