Classification of rotational special Weingarten surfaces of minimal type in {\mathbb{S}^2 \times \mathbb{R}} and {\mathbb{H}^2 \times \mathbb{R}}

In this paper we classify the complete rotational special Weingarten surfaces in ${\mathbb{S}^2 \times \mathbb{R}}$ and ${\mathbb{H}^2 \times \mathbb{R}}$ ; i.e. rotational surfaces in ${\mathbb{S}^2 \times \mathbb{R}}$ and ${\mathbb{H}^2 \times \mathbb{R}}$ whose mean curvature H and extrinsic curvature K _e satisfy H = f(H ² ? K _e ), for some function ${f \in \mathcal{C}^1([0,+\infty))}$ such that f(0) = 0 and 4x(f′(x))² < 1 for any x ≥ 0. Furthermore we show the existence of non-complete examples of such surfaces.     

On the cardinality of Urysohn spaces

Recently, in Cammaroto et al. (2013) [4] we obtained a generalization of the famous inequality established by A.V. Arhangel?ski? in 1969 for Hausdoff spaces. In this paper, following this line of research, we present a common variation of this inequality for Urysohn spaces by developing a Main Theorem for obtaining inequalities. In particular, we extend a 2006 inequality by Hodel for Urysohn spaces. Moreover, this extended inequality is used to analyze a result containing an increasing chain of spaces that satisfies the same cardinality inequality and this new result solves an open problem in Cammaroto et al. (2013) [4] for Urysohn spaces. This general theorem also provides a new cardinal inequality for Hausdorff spaces. The paper is concluded with some open problems.     

Sphaerococcus coronopifolius (Rhodophyta,Gigartinales): a Mediterranean red alga with potential and applications in restoration

Abstract

Experimental studies conducted on some species of Mediterranean red algae allowed to identify Sphaerococcus coronopifolius Stackhouse as a valid alternative to the Pacific alga Gloiopeltis furcata (Postels & Ruprecht) J. Agardh, for the extraction of a material usable as natural consolidant and adhesive in the field of restoration. Promising results have been observed by comparing the extracts obtained from these two algae after the same extraction procedure. Chemical analysis (FTIR) revealed that S. coronopifolius has qualities similar to G. furcata. Even more promising results for S. coronopifolius compared to G. furcata were observed after the analysis of pH and conductivity, and the adhesion tests carried out on both extracts.     

A modular approach to catalyst hydrophobicity for an asymmetric aldol reaction in a biphasic aqueous environment

Catalyst 5, an ion pair consisting of a hydrophilic cation and a lipophilic anion, fulfils the solubility requirements needed to couple efficiency (enantioselectivities and anti-diastereoselectivities up to > or = 99%) and catalyst recyclability in asymmetric aldol reactions under aqueous biphasic conditions.     

Ordered distribution of I and Cl in the low-temperature crystal structure of mutnovskite, Pb4As2S6ICl: An X-ray single-crystal study

To study the temperature-dependent structural changes and to analyze the crystal chemical behavior of the halogens as a function of temperature, a crystal of the recently discovered mineral mutnovskite, ideally Pb₂AsS₃(I,Cl,Br), has been investigated by X-ray single-crystal diffraction methods at 300 and 110 K. At room temperature (RT) mutnovskite was confirmed to possess a centrosymmetric structure-type, space group Pnma, while at low temperature (110 K) it adopts a non-centrosymmetric orthorhombic structure-type, space group Pnm2₁, with a=11.5394(9) Å, b=6.6732(5) Å, c=9.3454(7) Å, V=719.64(9) Å³ and Z=2. Mutnovskite reconverts to the centrosymmetric-type upon returning to RT thus indicating that the phase transition is completely reversible in character. The refinement of the LT-structure leads to a residual factor R=0.0336 for 1827 independent observed reflections [F_o>4σ(F_o)] and 80 variables. The crystal structure of cooled mutnovskite is topologically identical to that observed at RT and the slight structural changes occurring during the phase transition Pnma→Pnm2₁ are mainly restricted to the coordination polyhedra around Pb. The structure solution revealed that I and Cl are ordered into two specific sites. Indeed, the unique mixed (I,Cl) position in the RT-structure (Wyckoff position 4c) transforms into two 2a Wyckoff positions in the LT-structure hosting I and Cl, respectively.     

Cohomology of affine Artin groups and applications

The result of this paper is the determination of the cohomology of Artin groups of type and with non-trivial local coefficients. The main result

is an explicit computation of the cohomology of the Artin group of type with coefficients over the module Here the first standard generators of the group act by -multiplication, while the last one acts by -multiplication. The proof uses some technical results from previous papers plus computations over a suitable spectral sequence. The remaining cases follow from an application of Shapiro's lemma, by considering some well-known inclusions: we obtain the rational cohomology of the Artin group of affine type as well as the cohomology of the classical braid group with coefficients in the -dimensional representation presented in Tong, Yang, and Ma (1996). The topological counterpart is the explicit construction of finite CW-complexes endowed with a free action of the Artin groups, which are known to be spaces in some cases (including finite type groups). Particularly simple formulas for the Euler-characteristic of these orbit spaces are derived.