Oxime palladacycles revisited: stone-stable complexes nonetheless very active catalysts

Our review critically presents the main achievements, advantages, and limitations of oxime palladacycles as high-turnover catalysts for Heck, as well as homo- and cross-coupling reactions such as Suzuki-Miyaura, Stille, Ullmann-type, Cassar-Heck-Sonogashira, sila-Sonogashira, Glaser-type, Hiyama, and alkoxycarbonylation reactions. New developments in this area are reviewed from a mechanistic and synthetic point of view. The role of oxime palladacycles as a source of highly active zero-valent palladium species is also discussed.     

Slab Percolation and Phase Transitions for the Ising Model

We prove, using the random-cluster model, a strict inequality between site percolation and magnetization in the region of phase transition for the d-dimensional Ising model, thus improving a result of [5]. We extend this result also at the case of two plane lattices (slabs) and give a characterization of phase transition in this case. The general case of N slabs, with N an arbitrary positive integer, is partially solved and it is used to show that this characterization holds in the case of three slabs with periodic boundary conditions. AMS classification: 60K35, 82B20, 82A25     

Multivariate statistical tools applied to the characterization of the proteomic profiles of two human lymphoma cell lines by two-dimensional gel electrophoresis

Mantle cell lymphoma (MCL) cell lines have been difficult to generate, since only few have been described so far and even fewer have been thoroughly characterized. Among them, there is only one cell line, called GRANTA-519, which is well established and universally adopted for most lymphoma studies. We succeeded in establishing a new MCL cell line, called MAVER-1, from a leukemic MCL, and performed a thorough phenotypical, cytogenetical and molecular characterization of the cell line. In the present report, the phenotypic expression of GRANTA-519 and MAVER-1 cell lines has been compared and evaluated by a proteomic approach, exploiting 2-D map analysis. By univariate statistical analysis (Student's t-test, as commonly used in most commercial software packages), most of the protein spots were found to be identical between the two cell lines. Thirty spots were found to be unique for the GRANTA-519, whereas another 11 polypeptides appeared to be expressed only by the MAVER-1 cell line. A number of these spots could be identified by MS. These data were confirmed and expanded by multivariate statistical tools (principal component analysis and soft-independent model of class analogy) that allowed identification of a larger number of differently expressed spots. Multivariate statistical tools have the advantage of reducing the risk of false positives and of identifying spots that are significantly altered in terms of correlated expression rather than absolute expression values. It is thus suggested that, in future work in differential proteomic profiling, both univariate and multivariate statistical tools should be adopted.     

Novel miscible blends of poly(p-dioxanone) with poly(vinyl phenol)

Poly(p-dioxanone) (PPDO) has been blended with poly(vinyl phenol) (PVPh) and the PPDO/PVPh blends have been investigated using DSC, FTIR and POM. According to the single T_g criterion, miscibility has been found in the whole composition range for the blends obtained by solvent casting from dioxane solutions. The dependence of the T_g on composition shows negative deviation from the Fox equation. The interaction parameter, obtained from melting point depression analysis, χ₁₂ = ?1.0, confirms a thermodynamically miscible blend. Specific interactions have been analyzed by FTIR. The OH stretching region of PVPh indicates that upon addition of PPDO the hydroxyl–hydroxyl autoassociation interactions are mainly replaced by hydroxyl–carbonyl interassociation contacts, in detrimental of the possible hydroxyl–ether interactions. The carbonyl stretching region of pure PPDO is sensitive to intramolecular ether-ester interactions occurring in the oxyethanoate structures (–O–CH₂–CO–O–) present along the PPDO chain. The –O–CH₂–CO–O– structure presents only two minimum energy conformations, trans and cis, resulting in two different absorptions in the CO stretching region located respectively at about 1757 and 1732 cm^?1. Blending with PVPh promotes two new contributions red shifted by about 23 cm^?1 relative to the “free” CO components. Finally, POM analysis shows that the addition of PVPh to PPDO significantly decreases the crystallization rate of PPDO.     

Nanocharacterization techniques for investigating the durability of wood coatings

Nanocharacterization techniques such as nanoindentation and atomic force microscopy were used to investigate the exterior durability of waterborne coatings improved with inorganic nanosized UV-absorbers. Nanocomposite coatings for exterior uses of wood were formulated with different type of nanoparticles and their performance was evaluated trough artificial aging. Nanoindentation in continuous stiffness mode was used to demonstrate the changes of hardness and Young’s modulus of the coatings after accelerated weathering. The degradation mechanism of the surface coatings was investigated with atomic force microscopy that has provided valuable information on the morphological and microstructural changes of the surface coatings with the artificial aging. Additionally, the glass transition temperature and optical appearance changes were reported. The results obtained have shown that the nanoindentation technique in conjunction with atomic force microscopy can be satisfactorily used for durability investigation and service life prediction of nanocomposite coatings for wood.     

Metal-assisted ring-closing/opening process of a chiral tetrahydroquinazoline

The ring-chain tautomerism of a 2-aryl-1,2,3,4-tetrahydroquinazoline has been exploited to induce reversible changes in the aminal-imine equilibrium, as desired, by coordination of a suitable metal ion. This process was studied by NMR and UV-vis spectroscopies, X-ray crystallography, and molecular modeling approach. The results obtained show that the imine H(2)L(i) undergoes a selective ring-closing reaction upon complexation with Ni(2+). As a result, complexes of the type Ni(HL(a))(2) are obtained, whose chirality arises from the chiral ligand H(2)L(a) and the helicity of the structure. Hence, helical enantiomers form the following racemates: [Δ-C(R,R)N(S,S),Λ-C(S,S)N(R,R)]-Ni(HL(a))(2)·2HOAc and [Δ,Λ-C(S,R)N(R,S)]-Ni(HL(a))(2)·4MeOH. In contrast to the situation observed for Ni(2+), the cyclic tautomer of the ligand, H(2)L(a), undergoes a selective ring-opening reaction upon complex formation with Pd(2+), ultimately yielding Pd(HL(i))(2)·MeOH, in which the open-chain imine ligand is bidentate through the N,O donor set of the quinoline residue. Density functional theory calculations were conducted to provide insight into the different behavior of both coordinated metals (Ni(2+) and Pd(2+)) and to propose a mechanism for the metal-assisted opening/closing reaction of the tetrahydroquinazoline ring.     

The first steps of the Li‐B‐H cluster formation

We have theoretically investigated the formation of Li:B:H clusters from standard reactants in gas phase. Molecular electronic structure computations as well as Born‐Oppenheimer molecular dynamics have been carried out to investigate the early stages of the formation of Li:B:H clusters. We describe the thermochemical properties of the different possible reactions and the first stable structures that could initiate the growing process. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Numerical Solutions of Matrix Differential Models Using Higher-Order Matrix Splines

This paper deals with the construction of approximate solution of first-order matrix linear differential equations using higher-order matrix splines. An estimation of the approximation error, an algorithm for its implementation and some illustrative examples are included.     

Bounds on the crossing resolution of complete geometric graphs

The crossing resolution of a geometric graph is the minimum crossing angle at which any two edges cross each other. In this paper, we present upper and lower bounds to the crossing resolution of the complete geometric graphs.     

Properties of uncharged water-soluble tetra(ω-methoxypolyethyleneoxy)phthalocyanine free base: Viable switching of the optical response by means of H3O+ ions

An uncharged water-soluble tetra (ω-methoxypolyethyleneoxy)phthalocyanine was characterized by MALDI-TOF mass spectrometry, UV–vis and luminescence measurements. The polyether substituents render water soluble this uncharged phthalocyanine. Relevant changes are observed in emission measurements upon protonation. The phthalocyanine free base and its protonated forms can be switched alternating H₃O⁺ and OH^? ions as inputs, being the intensity of the luminescence spectra the output. Binary codes 1 or 0 can be assigned to the high luminescent phthalocyanine free base state or to the low luminescent protonated state, respectively. The read-out procedure is fast and the system is reversible. In addition, the exploiting of the luminescent properties of the present water soluble phthalocyanine could be of relevance also for biological applications (photosensitizers for the photodynamic therapy).