Noble gas anions: a theoretical investigation of FNgBN- (Ng = He-Xe)

Noble gas anions of general formula FNgBN- (Ng = He-Xe) have been investigated by MP2, coupled-cluster, and multireference-CI calculations with correlation-consistent basis sets. These species reside in deep wells on the singlet potential energy surface and are thermodynamically stable with respect to the loss of F, F-, BN, and BN-. They are unstable with respect to Ng + FBN-, but at least for Ng = Ar, Kr, and Xe, the involved energy barriers are high enough to suggest their conceivable existence as metastable species. The stability of FNgBN- arises from the strong F--stabilization of the elusive NgBN. The character of the boron-noble gas bond passes from purely ionic for FHeBN- and FNeBN- to covalent for FXeBN-.     

Foliations by stationary disks of almost complex domains

We study the problem of existence of stationary disks for domains in almost complex manifolds. As a consequence of our results, we prove that any almost complex domain which is a small deformation of a strictly linearly convex domain D⊂Cn with standard complex structure admits a singular foliation by stationary disks passing through any given internal point. Similar results are given for foliations by stationary disks through a given boundary point.     

Proton spin lattice relaxation times in biological tissues Water and lipid role

Abstract

The multiphase model of water present in biological tissues derives mainly from the N.M.R. observation of a fraction of non-freezing water in biological tissues which is attributable to the water bound to macromolecules. Studies of this problem rule out completely the lipids as the source of the NMR signal. Our studies on nuclear spin lattice relaxation times of human and animal tissues have been made to understand if other contributions to the N.M.R. signal are present in addition to that coming from the water protons. We have measured directly by the N.M.R. method the relative water and lipid content and the relaxation time T ₁ as a function of the water content which was varied by controlled dehydration. The results show clearly that lipids contribute actively to the N.M.R. signal and the fast relaxation time T ₁ which is of the order of 100 ms in all biological tissues is related to the lipids. In view of these experimental observations we think that it is opportune to reconsider critically all the determinations of the ‘bound water’ made by the freezing procedure with the N.M.R. technique, and dedicate more attention to the lipids of biological membranes.     

Nanoparticle microinjection and Raman spectroscopy as tools for nanotoxicology studies

Microinjection techniques and Raman spectroscopy have been combined to provide a new methodology to investigate the cytotoxic effects due to the interaction of nanomaterials with cells. In the present work, this novel technique has been used to investigate the effects of Ag and Fe(3)O(4) nanoparticles on Hela cells. The nanoparticles are microinjected inside the cells and these latter ones are probed by means of Raman spectroscopy after a short incubation time, in order to highlight the first and impulsive mechanisms developed by the cells to counteract the presence of the nanoparticles. The results put in evidence a different behaviour of the cells treated with nanoparticles in comparison with the control cells; these differences are supposed to be generated by an emerging oxidative stress due to the nanoparticles. The achieved results demonstrate the suitability of the proposed method as a new tool for nanotoxicity studies.     

Connections between Size Functions and Critical Points

A mathematical approach to the concept of shape of a submanifold ℳ︁ of a Euclidean space had previously been given by means of ‘measuring functions’ (e.g. diameter or volume) and of the derived ‘size functions’. This paper relates the study and the computation of any such size function to the structure of critical points of the associated measuring function.     

Geometrical shape comparison by size theory

Size Theory allows us to compare shapes of topological spaces and manifolds with respect to properties described by real functions. The main tools used in Size Theory are some pseudo-distances measuring the minimal changes of these real functions under the action of homeomorphisms. This method can be adapted to several different definitions of shape without changing its geometrical-topological framework. Some new results about this approach to shape comparison are illustrated. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Loss of ellipticity in additive logarithmic finite strain plasticity and related results on Hencky-type energies

The aim of this paper is to present some results regarding the Legendre-Hadamard ellipticity and loss of ellipticity of some energies depending on the logarithmic strain tensor. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

New Poincaré-type inequalities

We present some Poincaré-type inequalities for quadratic matrix fields with applications e.g. in gradient plasticity or fluid dynamics. In particular, applications to the pseudostress–velocity formulation of the stationary Stokes problem and to infinitesimal gradient plasticity are discussed.