Extraction methods of red blood cell membrane proteins for Multidimensional Protein Identification Technology (MudPIT) analysis

Since red blood cells (RBCs) lack nuclei and organelles, cell membrane is their main load-bearing component and, according to a dynamic interaction with the cytoskeleton compartment, plays a pivotal role in their functioning. Even if erythrocyte membranes are available in large quantities, the low abundance and the hydrophobic nature of cell membrane proteins complicate their purification and detection by conventional 2D gel-based proteomic approaches. So, in order to increase the efficiency of RBC membrane proteome identification, here we took advantage of a simple and reproducible membrane sub-fractionation method coupled to Multidimensional Protein Identification Technology (MudPIT). In addition, the adoption of a stringent RBC filtration strategy from the whole blood, permitted to remove exhaustively contaminants, such as platelets and white blood cells, and to identify a total of 275 proteins in the three RBC membrane fractions collected and analysed. Finally, by means of software for the elaboration of the great quantity of data obtained and programs for statistical analysis and protein classification, it was possible to determine the validity of the entire system workflow and to assign the proper sub-cellular localization and function for the greatest number of the identified proteins.     

KAM for quasi-linear and fully nonlinear forced perturbations of Airy equation

We prove the existence of small amplitude quasi-periodic solutions for quasi-linear and fully nonlinear forced perturbations of the linear Airy equation. For Hamiltonian or reversible nonlinearities we also prove their linear stability. The key analysis concerns the reducibility of the linearized operator at an approximate solution, which provides a sharp asymptotic expansion of its eigenvalues. For quasi-linear perturbations this cannot be directly obtained by a KAM iteration. Hence we first perform a regularization procedure, which conjugates the linearized operator to an operator with constant coefficients plus a bounded remainder. These transformations are obtained by changes of variables induced by diffeomorphisms of the torus and pseudo-differential operators. At this point we implement a Nash–Moser iteration (with second order Melnikov non-resonance conditions) which completes the reduction to constant coefficients.     

On families of quadratic surfaces having fixed intersections with two hyperplanes

We investigate families of quadrics all of which have the same intersection with two given hyperplanes. The cases when the two hyperplanes are parallel and when they are nonparallel are discussed. We show that these families can be described with only one parameter and describe how the quadrics are transformed as the parameter changes. This research was motivated by an application in mixed integer conic optimization. In that application, we aimed to characterize the convex hull of the union of the intersections of an ellipsoid with two half-spaces arising from the imposition of a linear disjunction.     

Dithioether ligands containing a 2,6‐disubstituted pyridine linker with two thioether‐heterocycle arms

The structure of 2,6‐bis(2‐pyridyltsulfanylmethyl)pyridine (pytmp), (I), C₁₇H₁₅N₃S₂, presents a twisted conformation, with the three planar moieties almost perpendicular to each other. The structures of two related derivatives, namely 2,6‐bis(6‐methyl‐2‐pyridylsulfanylmethyl)pyridine (mpytmp), (II), C₁₉H₁₉N₃S₂, and 2,6‐bis(4‐methyl‐2‐pyrimidylsulfanylmethyl)pyridine (mprtmp) n‐pentane hemisolvate, (III), C₁₇H₁₇N₅S₂·0.5C₅H₁₂, present extended planar fragments with just one quasi‐perpendicular arylsulfanylmethyl side arm, such that the molecules are folded in an L‐shaped conformation. All three conformations appear different from those adopted by similar compounds, demonstrating the great flexibility of such species, although such differences in conformational behaviour might drive specific coordination modes.     

A new family of heavy transition metal coordination compounds and its application,I. Design,synthesis and characterization of volatile organohafnium precursors

The first three representatives of a new family of volatile organohafnium compounds suitable as metallo-organic chemical vapour deposition precursors were synthesized. A combination of cyclopentadienyl and alkoxo-ligands with a bicyclo[2.2.1]heptanc framework was used. Volatility at relatively low temperatures for hafnium compounds was found and the precursors were characterized by elemental analysis and spectroscopic methods (IR, ¹H and ¹³C NMR, mass spectrometry and mass-analysed ion kinetic energy spectroscopy). The outlook for use in hafnium functional materials synthesis was derived from the fragmentation data.     

Operators which have a closed quasi-nilpotent part

We find several conditions for the quasi-nilpotent part of a bounded operator acting on a Banach space to be closed. Most of these conditions are established for semi-Fredholm operators or, more generally, for operators which admit a generalized Kato decomposition. For these operators the property of having a closed quasi-nilpotent part is related to the so-called single valued extension property.

     

Ordinary differential operators in Hilbert spaces and Fredholm pairs

Let be a path of bounded operators on a real Hilbert space, hyperbolic at . We study the Fredholm theory of the operator . We relate the Fredholm property of to the stable and unstable linear spaces of the associated system . Several examples are included to point out the differences with respect to the finite dimensional case, in particular concerning the role of the spectral flow. We define a general class of paths A for which many properties typical of the finite dimensional framework still hold. Our motivation is to develop the linear theory which is necessary for the set-up of Morse homology on Hilbert manifolds. Received: 9 March 2001; in final form: 1 March 2002 / Published online: 2 December 2002