Setting the basis for the interpretation of temperature first order reversal curve (TFORC) distributions of magnetocaloric materials

First Order Reversal Curve (FORC) distributions of magnetic materials are a well-known tool to extract information about hysteresis sources and magnetic interactions, or to fingerprint them. Recently, a temperature variant of this analysis technique (Temperature-FORC, TFORC) has been used for the analysis of the thermal hysteresis associated with first-order magnetocaloric materials. However, the theory supporting the interpretation of the diagrams is still lacking, limiting TFORC to a fingerprinting technique so far. This work is a first approach to correlate the modeling of first-order phase transitions, using the Bean–Rodbell model combined with a phenomenological transformation mechanism, with the features observed in experimental TFORC distributions of magnetocaloric materials. The different characteristics of the transformations, e.g., transition temperatures, symmetry, temperature range, etc., are correlated to distinct features of the distributions. We show a catalogue of characteristic TFORC distributions for magnetocaloric materials that exhibit some of the features observed experimentally.Army Research Laboratory W911NF-19-2-021

Reversibility of the Magnetocaloric Effect in the Bean-Rodbell Model

The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η≈1.3−1.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones.Universidad de Sevilla US-1260179Junta de Andalucía P18-RT-746Army Research Laboratory W911NF192021

Initiation codon selection is accomplished by a scanning mechanism without crucial initiation factors in sindbis virus subgenomic mRNA

© 2014 Garcia-Moreno et al. Translation initiation of alphavirus subgenomic mRNA (sgmRNA) can occur in the absence of several initiation factors (eIFs) in infected cells; however, the precise translation mechanism is still poorly understood. In this study, we have examined the mechanism of initiation and AUG selection in Sindbis virus (SINV) sgmRNA. Our present findings suggest that sgmRNA is translated via a scanning mechanism, since the presence of a hairpin structure before the initiation codon hampers protein synthesis directed by this mRNA. In addition, translation is partially recovered when an in-frame AUG codon is placed upstream of this hairpin. This scanning process takes place without the participation of eIF4A and active eIF2. These results, combined with our findings through modifying the SINV sgmRNA leader sequence, do not support the possibility of a direct initiation from the start codon without previous scanning, or a shunting mechanism. Moreover, studies carried out with sgmRNAs containing two alternative AUG codons within a good context for translation reveal differences in AUG selection which are dependent on the cellular context and the phosphorylation state of eIF2α. Thus, initiation at the additional AUG is strictly dependent on active eIF2, whereas the genuine AUG codon can start translation following eIF2α inactivation. Collectively, our results suggest that SINV sgmRNA is translated by a scanning mechanism without the potential participation of crucial eIFs. A model is presented that explains the mechanism of initiation of mRNAs bearing two alternative initiation codons.Ministerio de Economía y Competitividad, Spain) grant BFU2012-31861. M.G.-M. is holder of a FPI (Formación de Personal Investigador) fellowship. The Institutional Grant awarded to the Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM) by the Fundación Ramón Areces is acknowledged.Peer Reviewe

Inhibition of host protein synthesis by Sindbis virus: Correlation with viral RNA replication and release of nuclear proteins to the cytoplasm

© 2014 John Wiley & Sons Ltd. Infection of mammalian cells by Sindbis virus (SINV) profoundly blocks cellular mRNA translation. Experimental evidence points to viral non-structural proteins (nsPs), in particular nsP2, as the mediator of this inhibition. However, individual expression of nsP1, nsP2, nsP3 or nsP1-4 does not block cellular protein synthesis in BHK cells. Trans-complementation of a defective SINV replicon lacking most of the coding region for nsPs by the co-expression of nsP1-4 propitiates viral RNA replication at low levels, and inhibition of cellular translation is not observed. Exit of nuclear proteins including T-cell intracellular antigen and polypyrimidine tract-binding protein is clearly detected in SINV-infected cells, but not upon the expression of nsPs, even when the defective replicon was complemented. Analysis of a SINV variant with a point mutation in nsP2, exhibiting defects in the shut-off of host protein synthesis, indicates that both viral RNA replication and the release of nuclear proteins to the cytoplasm are greatly inhibited. Furthermore, nucleoside analogues that inhibit cellular and viral RNA synthesis impede the blockade of host mRNA translation, in addition to the release of nuclear proteins. Prevention of the shut-off of host mRNA translation by nucleoside analogues is not due to the inhibition of eIF2α phosphorylation, as this prevention is also observed in PKR-/- mouse embryonic fibroblasts that do not phosphorylate eIF2α after SINV infection. Collectively, our observations are consistent with the concept that for the inhibition of cellular protein synthesis to occur, viral RNA replication must take place at control levels, leading to the release of nuclear proteins to the cytoplasm.DGICYT (Dirección General de Investigación Científica y Técnica. Ministerio de Economía y Competitividad, Spain) grant (BFU2012-31861). Fundación Ramón ArecesPeer Reviewe

Influence of Thermal and Magnetic History on Direct DTad Measurements of Ni49+xMn36-xIn15 Heusler Alloys

In the present work, using Heusler Ni49+xMn36-xIn15 (with x = 0 and 0.5) alloys, it is shown that the choice of the appropriate measurement protocol (erasing the prior state of the sample in between experiments) in DTad first shot characterization is crucial for obtaining reliable results. Unlike indirect measurements, for which incorrect protocols produce overestimates of the characteristics of the material, erroneous direct measurements underestimate DTad in the region close to its first order phase transition. The error in DTad is found to be dependent on the temperature step used, being up to ~40% underestimation, including a slight shift in its peak temperature.AEI/FEDER-UE (project MAT-2016-77265-R)US Army Research Laboratory W911NF-19-2-021

Sobre el número de módulos fotovoltaicos en serie para aplicaciones de riego

En sistemas de riego fotovoltaico la tensión mínima en el bus de continua del variador de frecuencia (VF) es impuesta por la tensión necesaria a la entrada de la moto-bomba. Así, siempre que esta tensión es más grande que la tensión del punto de máxima potencia del generador fotovoltaico parte de la energía que este podría entregar no se utiliza. El objetivo de este trabajo es estudiar estas pérdidas para 20, 21 y 22 módulos en serie (para módulos de 60 células en serie). Se puede concluir que si no hay caídas de tensión entre el VF y la moto-bomba las pérdidas son depreciables. Sin embargo, el aumento de estas pérdidas lleva a un incremento del porcentaje de pérdidas en energía fotovoltaica. Además, se verifica un aumento de las pérdidas con el incremento de la temperatura de célula

Numerical Thermo-Mechanical Modelling Of Stress Fields and Residual Constraints in Metallic Targets Subject To Laser Shock Processing

In the analysis of the thermomechanical behaviour of the target material subject to Laser Shock Processing (LSP), most of the simplified models used for the analysis of its residual shocked state rely on rather simple estimations or material response equations that rarely take into account a detailed description of the material subject to a simultaneous dynamic compression and either deformation-induced or plasma-driven thermal heating. The calculational system developed by the authors (SHOCKLAS) includes a coupled analysis of the pressure wave applied to the target material as a result of the plasma buildup following laser interaction and the shock wave propagation into the solid material with specific consideration of the material response to thermal and mechanical alterations induced by the propagating wave itself (i.e. effects as elastic-plastic deformation, changes in elastic constants, etc.). The model is applicable to the typical behaviour shown by the different materials through their dynamic strain-stress relations. In the present paper, the key features and several typical results of the developed SHOCKLAS calculational system are presented. In particular, the application of the model to the realistic simulation (full 3D dependence, non linear material behaviour, thermal and mechanical effects, treatment over extended surfaces) of LSP treatments in the experimental conditions of the irradiation facility used by the authors is presente

Scientific and Technological Issues on the Application of High Intensity Lasers to Material Properties Modification: The case of Laser Shock Processing of Metallic Alloys

Laser Shock Processing (LSP) has been practically demonstrated as a technique allowing the effective induction of residual stresses fields in metallic materials allowing a high degree of surface material protection. Experimental results obtained with commercial Q-switched lasers prove complete feasibility at laboratory scale. Depending on initial material mechanicla properties, the remaining residual stresses fields can can reach depths and maximun values providing an effectively enhanced behaviour of materials against fatigue crack propagation, abrasive wear, chemical corrosion and other failure conditions. This makes the technique specially suitable and competitive with presently use techniques for the treatment of heavy duty components in the aeronautical, nuclear an automotive industries. However, according to the inherent difficulty for prediction of the shock waves generation (plasma) and evolution in treatedmaterials, the practical implementation of LSP processes needs an effective predictive assessment capability. A physically comprehensive calculational tool (SHOCKLAS) has been developed able to sistematically study LSP processe

Aplicación clínica de la técnica percutánea en la tenosinovitis estenosante de los flexores de la mano

Producción CientíficaLa tenosinovitis estenosante de los flexores de la mano es una patología que conduce al bloqueo de la polea de flexión proximal del dedo. Aunque el tratamiento inicial es conservador, si éste no es efectivo, está indicado el tratamiento quirúrgico mediante liberación abierta o percutánea. Material y método: Estudio descriptivo retrospectivo de 116 pacientes intervenidos de dedo en resorte en el HCUV (enero 2005- diciembre 2007), seguimiento medio 36 meses. Análisis de datos con el 91% de los pacientes (105 pacientes) con un total de 182 dedos afectos realizando comparación de ambas técnicas. Resultados: Edad media varones 53.70 años y la de las mujeres 53.95. El 34% de las manos intervenidas no presentan otras patologías asociadas. Primer dedo más afectado, seguido del tercero y cuarto. Se realizó técnica percutánea en el 42% de los pacientes, abierta en el 53% y ambas en el 5% del total. Destacan los problemas con la cicatriz en la tenolisis abierta. Técnica percutánea permite reincorporación a la vida laboral 8 días antes. Discusión: La liberación percutánea de la polea A1 es una alternativa a la liberación abierta por su bajo coste y por permitir una rápida reincorporación del paciente a su vida laboral. Gracias a estudios experimentales en cadáver, se obtienen referencias topográficas que aportan mayor seguridad, permitiendo ampliar el uso de esta técnica que ha demostrado grandes ventajas en el ámbito socio-económico y labora