On symmetry groups of quasicrystals

A relationship between two types of symmetry groups of quasicrystals in the cut-andproject model is studied.     

Mössbauer Investigation of the Itinerant Magnets U(Ga0.98Sn0.02)3 and CeFe2

The theoretical predictions that UGa₃ and CeFe₂ should be regarded as itinerant magnets stimulated new investigations. In this paper we focus on Mössbauer measurements aimed to characterize their magnetic properties. We show that the analysis of the transferred hyperfine interactions at the ¹¹⁹Sn nuclei in U(Ga_0.98Sn_0.02)₃, a type II antiferromagnet, provides direct information on the f-p hybridization and allows to determine the orientation of the U moments. The study of CeFe₂ demonstrates that the intrinsic ferromagnetism coexists with short range antiferromagnetic correlations. The instability of the ferromagnetic state is illustrated by doping CeFe₂ with a small amount of Co and by application of pressure on pure CeFe₂. Our results will be discussed in connection with neutron and synchrotron experiments.     

High‐spin states in tetrahedral X4 clusters (X = H,Li, Na,K)

The high‐spin electronic states for lithium, sodium, and potassium four‐atom clusters were studied. In particular, we performed coupled cluster geometry optimization of the quintet state in tetrahedral geometry. The quintet state of these systems is characterized by having all the valence electron unpaired, giving rise to the so‐called no‐pair bonding. Single‐point full configuration interaction computations on the equilibrium geometries for the various clusters are also presented. The analysis of the valence orbitals in a localized representation confirms the importance of the p atomic orbitals to explain this unusual type of bond. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Fuzzy relation equations theory as a basis of fuzzy modelling: An overview

We give a wide overview on the applications of fuzzy relation equations theory to decision-making processes, to the construction of preference relations and to Knowledge Engineering, mainly fuzzy control and fuzzy pattern recognition. General theoretical results and methodological aspects are pointed out.     

Determination of diphenhydramine hydrochloride by flow injection with bromophenol blue and turbidimetric measurement

The study of a number of diphenhydramine-dye systems was carried out in order to determine the most suitable precipitate for the turbidimetric determination of diphenhydramine using flow injection (FI). The reagent selected was Bromophenol Blue. The chemical and FI variables were optimised. The calibration graph was linear over the concentration range 50-230 p.p.m. of diphenhydramine hydrochloride. A number of interfering substances were also investigated.     

Homotopical linking and Morse index estimates in min-max theorems

The authors extend some well-known Morse estimates for critical points of saddle point type to some linking conditions recently considered in the literature. Applications are given for multiplicity results in PDE and existence of subharmonic solutions for a class of conservative ODE. Research supported by Program STRIDE (contract STRDA/C/CEN/531/92) and EC (contract ERBCHRXCT940555).