Detection of phosphorylation states by intermolecular sensitization of lanthanide-peptide conjugates

The luminescence of a designed peptide equipped with a coordinatively-unsaturated lanthanide complex is modulated by the phosphorylation state of a serine residue in the sequence. While the phosphorylated state is weakly emissive, even in the presence of an external antenna, removal of the phosphate allows coordination of the sensitizer to the metal, yielding a highly emissive supramolecular complex.     

Preliminary attempt to follow the enthalpy of an enzymatic reaction by ab initio computations: Catalytic action of papain

A new theoretical approach to study the enthalpy variations occurring during an enzymatic reaction is presented. The structural modifications of the enzyme–substrate complex along the reaction path are distinguished as macro- and microdeformations. Macrodeformations, which concern primarily the approach of the substrate to the enzyme and the release of the reaction products and arise from nonbonded interactions, are treated with an empirical method for computing the energy of a macromolecule. Microdeformations, which are local displacements driven by variations of the electronic structure and its energy and involve only a limited portion of the complex, are treated with the ab initio SCF-LCAO-MO method. The reaction path is idealized as a sequence of major steps: at each step, first the empirical program REFINE is used to calculate the geometry of the system for that step, then the energy of an appropriate subsystem is computed ab initio with the program IBMOL, using the geometry provided by REFINE and applying small concerted atomic displacements. Thus along the entire reaction path one can obtain an energy profile computed with the ab initio method and compatible with the structure of the whole complex. This approach was applied here to the first steps of the reaction of proteolysis catalyzed by papain. The formation of an ion pair ImH⁺ …S^? between the side chains of residues His-159 and Cys-25 was examined in detail. The results show that the instability of the ion pair decreases by ? 11.5 kcal/mol when the interactions with residues Asn-175 and Ala- 160 are taken into account; the instability is further decreased by ?2 kcal/mol after a partial geometry optimization. The energies of the noncovalent enzyme–substrate complex and of the tetrahedral intermediate were computed, considering N-methyl acetamide (NMA) as model substrate and representing papain with the residues Cys-25, His-159, Gln-19, and Ala-160. The interaction energy of the noncovalent complex is -3.8 kcal/mol, compared to the value of +7.4 kcal/mol for the CH₃S^? -NMA complex. The tetrahedral intermediate is found to be less stable than the noncovalent complex by 27 and 38.5 kcal/mol, respectively, for the papain–NMA and the CH₃S^? -NMA systems. While these rather large energy differences are possibly due to the incorrect geometry of the tetrahedral intermediate and optimization of the structure is required, it appears that the interactions with the various protein residues represent a very important stabilization factor, which lowers the onthalpy variations during the reaction.     

Comparative study of chained systems theory and fuzzy logic as a solution for the nonlinear lateral control of a road vehicle

This paper presents a comparative study of different lateral controllers applied to the autonomous steering of automobiles. The nonlinear nature of vehicle dynamics makes it a challenging problem in the Intelligent Transportation Systems (ITS) field, as long as a stable, accurate controller is compulsorily needed in order to ensure safety during navigation. The problem has been tackled under two different approaches. The first one is based on chained systems theory, while the second controller relies on fuzzy logic. A comparative analysis has been carried out based on the results achieved in practical trials. Real tests were conducted using a DGPS-driven electric Citroen Berlingo in a private test circuit located at the Industrial Automation Institute of the CSIC (Arganda del Rey, Madrid). The final results and conclusions are presented.     

Sobre la necesidad de controlar el error de discretización de elementos finitos en optimización de forma estructural con algoritmos evolutivos

This work analyzes the influence of the discretization error contained in the Finite Element (FE) analyses of each design configuration proposed by the structural shape optimization algorithms over the behavior of the algorithm. The paper clearly shows that if FE analyses are not accurate enough, the final solution provided by the optimization algorithm will neither be optimal nor satisfy the constraints. The need for the use of adaptive FE analysis techniques in shape optimum design will be shown. The paper proposes the combination of two strategies to reduce the computational cost related to the use of mesh adaptivity in evolutionary optimization algorithms: (a) the use of the algorithm described by Bugeda et al. [1] which reduces the computational cost associated to the adaptive FE analysis of each geometrical configuration and, (b) the successive increase of the required accuracy of the FE analyses in order to obtain a considerable reduction of the computational cost in the early stages of the optimization process.     

Nonlinear eigenvalues for anisotropic quasilinear degenerate elliptic equations

We consider the Dirichlet problem for a class of anisotropic degenerate elliptic equations.     

Molecular Dipole Evaluation Using Monolayer Films: Can Computations Link Theory with Experiments?

A novel computational approach is presented for the determination of the effective electrical dipole of amphiphile molecules in monolayers at the air‐water interface (Langmuir films). Results from ab initio computations on model compounds, combined with molecular mechanics simulations of the associated films are consistent with experimentally determined dipole data. Though presently at its preliminary stage, this method may prove helpful in elucidating structural features that are not otherwise experimentally accessible.     

PANI-CSA: An Easy Method to Avoid ITO Photolithography in PLED Manufacturing

In order to optimize polymer light emitting diode (PLED) performances, devices with holes injected through an Indium Tin Oxide (ITO) / Polyaniline (PANI) electrode into the polymer are much more efficient than devices fabricated with the anode made only by ITO. We demonstrated that by using doped PANI as hole injection layer in a polymer light emitting diode the manufacturing process can become simpler. Indeed, the pattern of conductive layer can be produced without ITO photolithography by UV exposition. As hole transporter layer, Poly(N-vinylcarbazole) (PVK) was spin coated over the doped PANI layer and a layer of tris (8-hydroxy) quinoline aluminum (Alq₃) was then thermally evaporated so as to form the electron transport layer. To complete the device structure, Aluminum contacts were deposited onto the organic layers by vacuum evaporation at low pressure. The layers were characterized by X-ray small-angle diffraction, IR Raman and UV-Vis spectroscopies. Devices without PANI and with PANI as HIL were studied.