Obtención de microestructuras de grano ultrafino en aleaciones de aluminio mediante extrusión en canal angular (ECAE)

Al 5083 samples have been subjected to 90º equal-channel angular extrusion (ECAE) at 270ºC. After ECAE, the microhardness was measured and the texture for the plane perpendicular to the extrusion direction was analysed by X-Rays and EBSD. The microstructure was characterized by optical microscopy and EBSD. As deformation accumulates the hardness increases until it reaches saturation at an effective strain of about ε∼4. With regard to the texture, it has been shown that a high density of {111} planes are oriented parallel to the shear plane of the last pass.<br><br>Varias muestras de aluminio 5083 se han sometido a extrusiones en canal angular de 90º a 270ºC. A continuación se midieron las durezas de las muestras obtenidas y se caracterizó la textura en el plano perpendicular a la dirección de extrusión mediante Rayos-X y difracción de electrones retrodispersados (EBSD). La caracterización microestructural se hizo mediante microscopio óptico y EBSD. Se ha observado que la dureza aumenta sensiblemente con el grado de deformación y que alcanza un nivel máximo de saturación a partir de ε∼4. En cuanto a la textura, se observa que los planos {111} tienden a orientarse paralelos al plano de la última cortadura

A theoretical study of the mechanism of rearrangement of dihydropyrimidines into pyrroles

Pyrimidines, pyrroles, cycloreversion,CO extrusion, Two possible mechanisms for the transformation of a 1,4-dihydropyrrolo[3,2-b]pyrrole derivative into a tetrasubstituted pyrrole have been studied theoretically and one of them has been found in reasonable accord with the experimental data. This mechanismis part of the very rare example of rearrangement of dihydropyrimidines into pyrroles

Unusual Complexes of P(CH)3 with FH, ClH, and ClF

© 2020 by the authors.Ab initio MP2/aug’-cc-pVTZ calculations have been performed to determine the structures and binding energies of complexes formed by phosphatetrahedrane, P(CH)3, and HF, HCl, and ClF. Four types of complexes exist on the potential energy surfaces. Isomers A form at the P atom near the end of a P-C bond, B at a C-C bond, C at the centroid of the C-C-C ring along the C3 symmetry axis, and D at the P atom along the C3 symmetry axis. Complexes A and B are stabilized by hydrogen bonds when FH and ClH are the acids, and by halogen bonds when ClF is the acid. In isomers C, the dipole moments of the two monomers are favorably aligned but in D the alignment is unfavorable. For each of the monomers, the binding energies of the complexes decrease in the order A > B > C > D. The most stabilizing Symmetry Adapted Perturbation Theory (SAPT) binding energy component for the A and B isomers is the electrostatic interaction, while the dispersion interaction is the most stabilizing term for C and D. The barriers to converting one isomer to another are significantly higher for the A isomers compared to B. Equation of motion coupled cluster singles and doubles (EOM-CCSD) intermolecular coupling constants J(X-C) are small for both B and C isomers. J(X-P) values are larger and positive in the A isomers, negative in the B isomers, and have their largest positive values in the D isomers. Intramolecular coupling constants 1J(P-C) experience little change upon complex formation, except in the halogen-bonded complex FCl:P(CH3) AThis work was carried out with financial support from the Ministerio de Ciencia, Innovación y Universidades of Spain (Project No. PGC2018–094644-B-C22) and Comunidad Autónoma de Madrid (P2018/EMT–4329 AIRTEC-CM)

How Aromatic Fluorination Exchanges the Interaction Role of Pyridine with Carbonyl Compounds: The Formaldehyde Adduct

The rotational spectrum of the weakly bound complex pentafluoropyridine⋅⋅⋅formaldehyde has been investigated using Fourier transform microwave spectroscopy. From the analysis of the rotational parameters of the parent species and of the 13C and 15N isotopologues, the structural arrangement of the adduct has been unambiguously established. The full ring fluorination of pyridine has a dramatic effect on its binding properties: It alters the electron density distribution at the π-cloud of pyridine creating a π-hole and changing its electron donor-acceptor capabilities. In the complex, formaldehyde lies above the aromatic ring with one of the oxygen lone pairs, as conventionally envisaged, pointing toward its centre. This lone pair⋅⋅⋅π-hole interaction, reinforced by a weak C−H⋅⋅⋅N interaction, indicates an exchange of the electron-acceptor roles of both molecules when compared to the pyridine⋅⋅⋅formaldehyde adduct. Tunnelling doublets due to the internal rotation of formaldehyde have also been observed and analysed leading to a discussion on the competition between lone pair⋅⋅⋅π-hole and π⋅⋅⋅π stacking interactions

Prescripción inducida en atención primaria de la Comarca Bilbao

ObjetivosPrincipales: conocer la proporción de prescripción inducida (PI) en Comarca Bilbao y su procedencia, la proporción de gasto correspondiente a la PI, la proporción de PI en los principales grupos terapéuticos, la actitud del médico de atención primaria ante la prescripción solicitada y su influencia en el gasto, la proporción de desacuerdo con dicha prescripción y los motivos de desacuerdo, y la proporción con informe del especialista. Secundarios: conocer la proporción de PI en los demás grupos terapéuticos, en fármacos VINE, EFG y en los de nula o baja mejora terapéutica.Diseño.Estudio transversal, descriptivoEmplazamientoAtención primariaParticipantesFármacos financiables prescritos por y/o solicitados a los médicos de familia de EAP.Resultados principalesSe estudiaron 7.922 fármacos. Tipo de prescripción: PI, 48,3% (IC del 95%, 47,2–49,4); del médico de atención primaria (PRO), 50,6% (IC del 95%, 49,5–51,7); desconocida, 1,1% (IC del 95%, 0,9–1,3). Procedencia principal: especialista público (72,2%), especialista privado (16,6%). Un 62,5% del gasto correspondió a la PI. En el grupo terapéutico más prescrito, sistema nervioso central (24,2%), PI, 39,8%; PRO, 58,9%; en aparato cardiovascular (19,1%), PI, 56,2%, PRO, 43,1%. Se prescribió el fármaco solicitado en un 98,4% de los casos, se cambio en el 1,2% y se suprimió en un 0,4%. Proporción de desacuerdo, 11%; motivos de desacuerdo, no hay necesidad de tratar (23,9%), grupo terapéutico (34,4%), principio activo (13,2%), marca comercial (28,5%). Hubo informe de especialista en un 62,4% de los casos.ConclusionesSe detecta una proporción considerable de prescripción no atribuible a atención primaria y una proporción importante de fármacos que el médico de primaria prescribe sin estar de acuerdo. Sería necesario un sistema que permitiera separar el gasto por niveles, así como mejorar la comunicación entre éstos.ObjectivesMain objetives: to know the proportion of induced prescription (IP) in Area Bilbao and its source, the proportion of cost IP accounts for, the proportion of IP in the main therapeutic groups, the attitude of GP when requested for prescription and its influence on cost, the proportion of disagreement with requested prescription, the reasons for disagreement, and the proportion with letter from specialist. Secondary objectives: to know the proportion of IP in the remaining therapeutic groups, in drugs of low clinical value, in generic drugs and in new drugs with low or no therapeutic improvement.DesignA descriptive cross-sectional study.SettingPrimary health care.ParticipantsDrugs prescribable under National Health Service prescribed by and/or requested to GPs.Main results7.922 drugs were analysed. Type of prescription: IP, 48.3% (95% CI, 47.2–49.4); GP prescription (GPP), 50.6% (95% CI, 49.5–51.7); unknown source, 1,1% (95% CI, 0.9–1.3). Main source, public specialist (72.2%), private specialist (16.6%). IP accounted for 62.5% of cost. In the most prescribed therapeutic group, central nervous system (24.2%), IP, 39.8%; GPP, 58.9%; in cardiovascular system (19.1%), IP, 56.2%; GPP, 43.1%. 98.4% of requested prescription was actually prescribed, 1.2% was changed and 0.4%, suppressed. Proportion of disagreement, 11%; reasons for disagreement, no need for medical treatment (23.9%), therapeutic group (34.4%), active ingredient (13.2%), brand name (28.5%). There was a 62.4% with letter from specialist.ConclusionsPrimary care is not accountable for a substantial proportion of prescription. GP prescribes a considerable proportion of drugs without agreement. It would be necessary a system that allows to separate the cost by care levels and also improve their communication

A multiscale material model for metallic powder compaction during hot isostatic pressing

The prediction of the distortions during Near-Net-Shape Hot Isostatic Pressing (NNS-HIP) is an intrinsic multiscale problem where the local interactions among particles determine the macroscopic distortions taking place during the sintering and densification of a component. In this work, a multiscale approach is proposed to solve this problem. In particular, a viscoplastic constitutive model capable of predicting macroscopic contractions during a HIP process with high accuracy has been developed, implemented and validated. The macroscopic model incorporates the mechanical behaviour predicted at the meso-scale by means of multiple-particle finite element models (MP-FEM) of an agglomerate of powder particles. The model is validated through the prediction of distortions during HIP of a full scale industrial case. It is concluded that adding the microscopic information of the HIP process to simulate the contractions at the macroscopic level results in a considerable improvement of the accuracy of the predictions

An Exploration of the Ozone Dimer Potential Energy Surface

The (O3)2 dimer potential energy surface is thoroughly explored at the ab initio CCSD(T) computational level. Five minima are characterized with binding energies between 0.35 and 2.24 kcal/mol. The most stable may be characterized as slipped parallel, with the two O3 monomers situated in parallel planes. Partitioning of the interaction energy points to dispersion and exchange as the prime contributors to the stability, with varying contributions from electrostatic energy, which is repulsive in one case. Atoms in Molecules analysis of the wavefunction presents specific O⋯O bonding interactions, whose number is related to the overall stability of each dimer. All internal vibrational frequencies are shifted to the red by dimerization, particularly the antisymmetric stretching mode whose shift is as high as 111 cm−1. In addition to the five minima, 11 higher-order stationary points are identified

Synthesis, Cell-Surface Binding, and Cellular Uptake of Fluorescently Labeled Glucose−DNA Conjugates with Different Carbohydrate Presentation

8 páginas, 5 figurasOligonucleotide conjugates carrying carbohydrates at the 5′-end have been prepared. Glucose, fucose, and saccharides containing glucose at the nonreducing end were attached to DNA strands using the classical phosphoramidite chemistry. Two types of spacers and a dendron scaffold helped to obtain a diversity of sugar presentations in the DNA conjugates. Cellular surface adsorption and cellular uptake of carbohydrate oligonucleotide antisense sequences were measured using flow cytometric analysis. Conjugates with the glucose moiety linked through long spacers (15 to 18 atom distances) were internalized better than those with short linkers (4 atom distance) and than DNA control strands without sugar modification. Conjugates with tetravalent presentation of glucose did not improve cell uptake.This work was supported by Consejo Superior de Investigaciones Científicas (PIF06-045); Spanish Ministry of Science (grants BFU2007-63287, BFU2007-62062, CTQ2006-01123,CTQ2009-13705), Generalitat de Catalunya (2009/SGR/208),and Instituto de Salud Carlos III (CIBER-BNN, CB06_01_0019). RL thanks CSIC for a JAE contract.Peer reviewe

Digital image correlation after focused ion beam micro-slit drilling: A new technique for measuring residual stresses in hardmetal components at local scale

A new method has been developed for measuring residual stresses at the surface of hardmetal components with higher spatial resolution than standard X-ray diffraction methods. It is based on measuring the surface displacements produced when stresses are partially released by machining a thin slit perpendicularly to the tested surface. Slit machining is carried out by focused ion beam (FIB). Measurement of the displacement fields around the FIB slit are performed by applying an advanced digital image correlation algorithm based on Fourier analysis with sub-pixel resolution. This method compares SEM images of the same area of the hardmetal surface before and after slitting. The method has been successfully applied to as-ground and femto-laser textured surfaces showing good correlation with the standard sin2 ψ XRD technique. It is concluded that texturing induced by laser pulses in the femtoseconds regime is not perfectly adiabatic, since residual stresses are reduced by 15