Multi‐Use NBD‐Based Tetra‐amino Macrocycle: Fluorescent Probe for Metals and Anions and Live Cell Marker

Ligand L (4‐(7‐nitrobenzo[1,2,5]oxadiazole‐4‐yl)‐1,7‐dimethyl‐1,4,7,10‐tetra‐azacyclododecane) is a versatile fluorescent sensor useful for Cu^II, Zn^II and Cd^II metal detection, as a building block of fluorescent metallo‐receptor for halide detection, and as an organelle marker inside live cells. Ligand L undergoes a chelation‐enhanced fluorescence (CHEF) effect upon metal coordination in acetonitrile solution. In all three complexes investigated the metal cation is coordinatively unsaturated; thus, it can bind secondary ligands as anionic species. The crystal structure of [Zn L Cl](ClO₄) is discussed. Cu^II and Zn^II complexes are quenched upon halide interaction, whereas the [Cd L ]²⁺ species behaves as an OFF–ON sensor for halide anions in acetonitrile solution. The mechanism of the fluorescence response in the presence of the anion depends on the nature of the metal ion employed and has been studied by spectroscopic methods, such as NMR spectroscopy, UV/Vis and fluorescence techniques and by computational methods. Subcellular localization experiments performed on HeLa cells show that L mainly localizes in spot‐like structures in a polarized portion of the cytosol that is occupied by the Golgi apparatus to give a green fluorescence signal.     

On independent varieties and some related notions

We investigate the relation of independence between varieties, as well as a generalisation of such which we call strict quasi-independence. Concerning the former notion, we specify a procedure for constructing an independent companion of a given solvable subvariety of a congruence modular variety; we show that joins of independent varieties inherit Mal’cev properties from the joinands; we investigate independence in 3- and 4-permutable varieties; we provide a more economical axiomatisation for the join of two independent varieties than the ones available in the literature. We also explore the latter notion, showing inter alia that joins of strictly quasi-independent varieties inherit the congruence extension property and the strong amalgamation property from the joinands, and conversely. An application section investigates independent varieties of Boolean algebras with operators (in particular, Akishev and Goldblatt’s bounded monadic algebras) and of groups. In particular, a complete characterisation of independent varieties of groups is given.     

Carbonylation of styrenes catalyzed by bioxazoline Pd(II) complexes: mechanism of enantioselectivity

Preliminary studies of the elementary steps involved in the reaction of a chiral methyl carbonyl bioxazoline Pd(II) complex with aromatic olefins and CO have allowed development of a new enantioselective catalytic carbonylation process, leading to γ-ketoester derivatives with high yield and good enantiomeric excess. The intermediate palladacycle complexes have been isolated and characterized by NMR spectroscopy and X-ray diffraction. Factors that govern the stereoselectivity of the olefin carbonylation process are discussed.     

Unitary representations of groups,continuity and spectrum

Let \({\mathcal{L}(H)}\) be the algebra of all bounded operators in a Hilbert space H, \({\theta : G \rightarrow \mathcal{L}(H)}\) denotes a strongly continuous unitary representation of a locally compact and second countable group G in H, σ(θ(g)) the spectrum of θ(g) and Conv(S) the convex hull of any subset S in a vector space. We prove here that θ is uniformly continuous if and only if \({\{g\in G/0\notin {\rm Conv}(\sigma(\theta(g)))\}}\) is non-meager.     

Lattice-theoretic properties of algebras of logic

In the theory of lattice-ordered groups, there are interesting examples of properties — such as projectability — that are defined in terms of the overall structure of the lattice-ordered group, but are entirely determined by the underlying lattice structure. In this paper, we explore the extent to which projectability is a lattice-theoretic property for more general classes of algebras of logic. For a class of integral residuated lattices that includes Heyting algebras and semi-linear residuated lattices, we prove that a member of such is projectable iff the order dual of each subinterval [a,1]$[a,1]$ is a Stone lattice. We also show that an integral GMV algebra is projectable iff it can be endowed with a positive Gödel implication. In particular, a ΨMV or an MV algebra is projectable iff it can be endowed with a Gödel implication. Moreover, those projectable involutive residuated lattices that admit a Gödel implication are investigated as a variety in the expanded signature. We establish that this variety is generated by its totally ordered members and is a discriminator variety.     

Mesophase structure of low‐wetting liquid crystalline polyacrylates with new perfluoroalkyl benzoate side groups

The synthesis, thermal behavior, bulk microstructure, and wettability of new polyacrylates carrying spaced 4‐perfluorohexylpropyl benzoate and 4‐perfluorooctylpropyl benzoate units in the side groups were investigated. X‐ray diffraction analysis proved the formation of different smectic mesophases (SmI₂, SmF₂, and SmC₂) and the evolution of their structures and lattice parameters with temperature. The mesophase polymorphic behavior depended on the length of the perfluorinated chain segment in the repeat unit. The electron density profiles along the smectic layer normal were drawn and provided a deeper insight into the packing of the side chains in a tilted, double layer structure. Thin polymer films were cast from solution, and their low wettability was established by measurements of contact angles with different probing liquids. We suggest that the hydrophobicity and lipophobicity of the films are enhanced by the mesophase surface structure which is mediated by the high‐order, mesophase bulk structure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4128–4139, 2010     

Almost global existence for solutions of a nonlinear fourth order hyperbolic equation

We study the long time existence of the solutions of the Cauchy problem for a class of nonlinear fourth order hyperbolic equations, in which the principal part is given by the composition of two waves operators with different propagation speeds. The presence of these two speeds makes this problem essentially different from the correspondent one for the second order wave equation. In fact, in the present case, we cannot apply the approach of S. Klainerman, based on the invariance of the D'Alembertian operator under the complete Lorentz group. Furthermore, even the alternative method used by F. John and S. Klainerman, only for the wave equation in three space dimensions, does not seem directly applicable. Nevertheless, thanks to the special structure of the equations, we are able to show the almost global existence of the solutions to the related Cauchy problem. Received December 29, 1995