Crystallization of Arthrobacter sp. strain 1C N-(1-D-carboxyethyl)-L-norvaline dehydrogenase and its complex with NAD+

The novel NAD+-linked opine dehydrogenase from a soil isolate Arthrobacter sp. strain 1C belongs to an enzyme superfamily whose members exhibit quite diverse substrate specificites. Crystals of this opine dehydrogenase, obtained in the presence or absence of co-factor and substrates, have been shown to diffract to beyond 1.8 ? resolution. X-ray precession photographs have established that the crystals belong to space group P21212, with cell parameters a = 104.9, b = 80.0, c = 45.5 ? and a single subunit in the asymmetric unit. The elucidation of the three-dimensional structure of this enzyme will provide a structural framework for this novel class of dehydrogenases to enable a comparison to be made with other enzyme families and also as the basis for mutagenesis experiments directed towards the production of natural and synthetic opine-type compounds containing two chiral centres.     

Trimethoxysilylpolymethacrylate as new material for stone conservation. Porosimetric and colorimetric investigations

Aimed to obtain new materials for the conservation of stone substrates, we report here on the synthesis of a polymer which has been obtained by inducing polymerization on a methacrylate monomer functionalized by alchoxysilane groups. Two lithotypes, the Comiso calcarenite and Mistretta quartzite, stones largely used in artworks of north-eastern Sicily, were treated with the above polymer and its conserving efficacy evaluated in terms of porosimetric features, hydric properties and appearance. The collected data were compared to those provided, under the same experimental conditions, by an ethylmethacrylate/methylmethacrylate copolymer and an alkylalchoxysilane, products widely employed in the protection of stones. Experiments aimed to test the durability of the above polymer against UV artificial ageing are also reported.     

How to embed three-dimensional flexible electrodes in microfluidic devices for cell culture applications

This communication describes a simple, rapid and cost effective method of embedding a conductive and flexible material within microfluidic devices as a means to realize uniform electric fields within cellular microenvironments. Fluidic channels and electrodes are fabricated by traditional soft-lithography in conjunction with chemical etching of PDMS. Devices can be deformable (thus allowing for a combination of electro-mechanical stimulation), they are made from inexpensive materials and easily assembled by hand; this method is thus accessible to a wide range of laboratories and budgets.     

Projections of Gibbs States for Hölder Potentials

We give a short proof that the projection of a Gibbs state for a Hölder continuous potential on a mixing shift of finite type under a 1-block fiber-wise mixing factor map has a Hölder continuous g function. This improves a number of previous results. The key insight in the proof is to realize the measure of a cylinder set in terms of positive operators and use cone techniques.     

Synthesis and reactivity of formamidinato rhodium(I) complexes

The syntheses of [Rh(diol)(formamidine)]₂ complexes (diol  cycloocta-1,5-diene (1); diol  norbornadiene (2); formamidine  N,N′-di-p-tolylformamidine) are reported. These complexes are dimeric and contain the bridging formamidino ligand. They react with CO, dppe and PPh₃ with displacement of the diene ligand to yield the known [Rh(CO)₂(formamidine)]₂, [Rh(dppe)₂]⁺ and [Rh(PPh₃)₂(formamidine)], respectively; the last complex, in which the formamidine acts as a chelating ligand, was isolated only as the O₂ adduct. With HCl or HBF₄ aqueous 1 and 2 do not form hydrides but instead the formamidino cation [p-tolyl-NHCHNHtolyl-p]⁺ and the complexes [Rh(diol)X]₂ (X  Cl, F); a possible scheme for the reaction with HCl is proposed. The [Rh(C₈H₁₂)(formamidine)]₂ complex reacts with heterocumulenes as CS₂, SO₂, PhNCS and PhNCO with diene displacement; the only product isolated was [Rh(CS₂)₂(formamidine], to which a polymeric structure is assigned.     

The mechanism of formation of π-allyl complexes: The reaction of PdCl2−4 with isoprene in methanol

A kinetic study of the reaction between PdCl^2?₄ and isoprene is described. The results are interpreted in terms of the formation of two π-complexes between palladium(II) and isoprene, one having only one double bond coordinated to the metal, the other being a chelated diene compound. Nucleophilic attack of solvent methanol on these intermediate complexes gives the methoxy π-allyl complex.     

Redox-active dirhodium(II,II) species covalently entrapped into a methylmethacrylate backbone

A novel class of polymers was obtained by insertion of dirhodium(II,II) metal systems into a methacrylate backbone; the synthesis was realized by free radical polymerization of an appropriate methacrylate-functionalized dirhodium polymer precursor, namely [Rh2(form)2(MA-COO)2](form =N,N'-di-p-tolylformamidinate)(MA-COO = 2-(methacroyloxy)ethyl-phthalate), with methylmethacrylate (MMA); the new copolymers, in solution, show reversible CO-absorption, connected to the axial reactivity of dirhodium(II,II) species.     

Computable error bounds for pointwise derivatives of a Neumann problem

In this paper we discuss the recovery of derivatives and thecomputation of rigorous and useful upper bounds for the pointwiseerror in the recovered derivatives, for finite element approximationsof the Laplace equation with Neumann boundary conditions, especiallyat points close to or on a smooth, curved boundary. We analyzethe dipole image technique for the case of curved boundaries,and show how to compute reliable recovered derivatives and errorbounds even in the limiting case of points lying on the curvedboundary. Numerical experiments show reasonably tight errorbounds for points both close to and away from a curved boundary.     

Die Anwendung der Dynamischen Optimierung bei der Sozial-Sanitären Bezirkseinteilung

Zusammenfassung Nach einer kurzen Analyse des Problems der optimalen Aufteilung eines geographischen Gebietes in sozial-sanitäre Bezirke wird in der vorliegenden Arbeit für die Lösung eines solchen Problems ein Modell dynamischer Programmierung verwendet. Es werden dann zwei Algorithmen vorgeschlagen: der erste, der von der territorialen Einheit ausgeht, soll die zulässigen sozial-sanitären Bezirke unter Berücksichtigung der Faktoren Nähe, Dichte und begrenzter Bevölke-rungsunterschied ermitteln; der zweite errechnet jene Gesamtheit der zulässigen Bezirke, die, jede territoriale Einheit nur einmal deckend, eine Zielfunktion auf ein Minimum reduziert, die das Gleichgewicht zwischen Angebot und Nachfrage der sozial-sanitären Dienste jedes Bezirks garantiert und erlaubt, die maximale Geschlossenheit der Bezirke zu erreichen. Schließlich wurde das vorgeschlagene Verfahren bei der optimalen Aufteilung eines unterregionalen Gebietes des sizilianischen Territoriums in sozial-sanitären Bezirke angewendet.

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Summary In this work, after a short analysis of the optimal division of a geographical area in the socio-sanitary districts a dynamic programming model is used for the solution of such problem. Therefore, two algorithms are suggested: the former, starting from the territorial units, is used to generate the admissible socio-sanitary districts, considering the adjacency, compactness and population limited deviation ties. The latter specifies the set of the admissible districts which, covering only once each territorial unit, minimizes the objective-function, which warrants a balance between supply and demand of socio-sanitary services in every district and permits to pursue the best compactness of the districts themselves. Finally, the suggested procedure is applied in the optimal division of a sub-regional area of the sicilian territory in the socio-sanitary districts.

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Die Arbeit wurde mit dem Beitrag des Nationalen Rats für Forschung von Italien erstellt.