On Fabry P\'erot Etalon based Instruments. I. The Isotropic Case

Here we assess the spectral and imaging properties of Fabry P\'erot etalons when located in solar magnetographs. We discuss the chosen configuration (collimated or telecentric) for both ideal and real cases. For the real cases, we focus on the effects caused by the polychromatic illumination of the filter by the irregularities in the optical thickness of the etalon and by deviations from the ideal illumination in both setups. We first review the general properties of Fabry P\'erots and we then address the different sources of degradation of the spectral transmission profile. We review and extend the general treatment of defects followed by different authors. We discuss the differences between the point spread functions (PSFs) of the collimated and telecentric configurations for both monochromatic and (real) quasi-monochromatic illumination of the etalon. The PSF corresponding to collimated mounts is shown to have a better performance, although it varies from point to point due to an apodization of the image inherent to this configuration. This is in contrast to the (perfect) telecentric case, where the PSF remains constant but produces artificial velocities and magnetic field signals because of its strong spectral dependence. We find that the unavoidable presence of imperfections in the telecentrism produces a decrease of flux of photons and a shift, a broadening and a loss of symmetrization of both the spectral and PSF profiles over the field of view, thus compromising their advantages over the collimated configuration. We evaluate these effects for different apertures of the incident beam.Comment: 20 pages 22 figures 2 Appendice

The European Solar Telescope

The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l'Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems

The European Solar Telescope

The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l’Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems

Use of a palladium catalyst to improve the capacity of activated carbon to absorb ethylene, and its effect on tomato ripening

The aims of this work were to study the ethylene adsorption capacity of different types and masses of activated carbon, to predict the performance of the ethylene adsorption process, to improve the removal of ethylene by impregnating granular activated carbon (GAC) with palladium, and to analyse the effect of this product on the removal of ethylene released from tomatoes. In an in vitro system, both GAC and powdered activated carbon (PAC) effectively absorbed exogenous ethylene; GAC was the most effective. Maximum adsorption was achieved with carbon masses of 1.25 g L-1 or greater. The best model describing the adsorption of ethylene by GAC was the Langmuir isotherm. To increase ethylene removal, a system involving an adsorbent (GAC) and a catalyst (1% palladium) was developed. This was tested in an in vivo experiment involving the removal of ethylene produced by three tomato cultivars inside sealed jars. Ethylene removal led to a delay in tomato ripening; smaller changes in fruit firmness and colour were observed compared to controls. This system could provide a useful way of eliminating ethylene from storage areas and thus maintaining tomato fruit quality, which can be negatively affected by ethylen

On Fabry-P\'erot etalon-based instruments. IV. Analytical formulation of telecentric etalons

Fabry-P\'erot etalons illuminated with collimated beams have been characterized analytically in detail since their invention. Meanwhile, most of the features of etalons located in telecentric planes have been studied only numerically, despite the wide use of this configuration in astrophysical instrumentation over decades. In this work we present analytical expressions for the transmitted electric field and its derivatives that are valid for etalons placed in slow telecentric beams, like the ones commonly employed in solar instruments. We use the derivatives to infer the sensitivity of the electric field to variations in the optical thickness for different reflectivities and apertures of the incident beam and we compare them to the collimated case. This allows us to estimate the wavefront degradation produced by roughness errors on the surfaces of the Fabry-P\'erot and to establish the maximum allowed RMS value of the cavity irregularities across the footprint of the incident beam on the etalon that ensures diffraction-limited performance. We also evaluate the wavefront degradation intrinsic to these mounts, which is produced only by the finite aperture of the beam and that must be added to the one produced by defects. Finally, we discuss the differences in performance of telecentric and collimated etalon-based instruments and we generalize our formulation to anisotropic etalons.Comment: 10 pages, 7 figure

Structural basis of the inhibition of GH1 β-glucosidases by multivalent pyrrolidine iminosugars

10 pags., 6 figs., 1 tab.The synthesis of multivalent pyrrolidine iminosugars via CuAAC click reaction between different pyrrolidine-azide derivatives and tri- or hexavalent alkynyl scaffolds is reported. The new multimeric compounds, together with the monomeric reference, were evaluated as inhibitors against two homologous GH1 β-glucosidases (BglA and BglB from Paenibacillus polymyxa). The multivalent inhibitors containing an aromatic moiety in the linker between the pyrrolidine and the scaffold inhibited the octameric BglA (µM range) but did not show affinity against the monomeric BglB, despite the similarity between the active site of both enzymes. A modest multivalent effect (rp/n = 12) was detected for the hexavalent inhibitor 12. Structural analysis of the complexes between the monomeric and the trimeric iminosugar inhibitors (4 and 10) and BglA showed the insertion of the inhibitors at the active site of BglA, confirming a competitive mode of inhibition as indicated by enzyme kinetics. Additionally, structural comparison of the BglA/4 complex with the reported BglB/2F-glucose complex illustrates the key determinants responsible for the inhibitory effect and explains the reasons of the inhibition of BglA and the no inhibition of BglB. Potential inhibition of other β-glucosidases with therapeutic relevance is discussed under the light of these observations.This work was supported by the Spanish Ministry of Economyand Competitiveness (CTQ2016-77270-R, BIO2016-76601-C3-3-R,AGL2016-75245-R), the Junta de Andalucía (FQM-345), MIUR-Italy(“Progetto Dipartimenti di Eccellenza 2018-2022” allocated toDepartment of Chemistry “Ugo Schiff”) and Ente Cassa di Risparmio di Firenze (grant n°. 2016/0845). M. Martínez-Bailén acknowledges theSpanish government for a FPU fellowship. We thank CITIUS-Universityof Seville (MS and NMR facilities) and the Synchrotron RadiationSource at Alba (Barcelona, Spain) for assistance at BL13-XALOCbeamlin

Structure-based identification and biological characterization of new NAPRT inhibitors

NAPRT, the rate-limiting enzyme of the Preiss–Handler NAD biosynthetic pathway, has emerged as a key biomarker for the clinical success of NAMPT inhibitors in cancer treatment. Previous studies found that high protein levels of NAPRT conferred resistance to NAMPT inhibition in several tumor types whereas the simultaneous blockade of NAMPT and NAPRT results in marked anti-tumor effects. While research has mainly focused on NAMPT inhibitors, the few available NAPRT inhibitors (NAPRTi) have a low affinity for the enzyme and have been scarcely characterized. In this work, a collection of diverse compounds was screened in silico against the NAPRT structure, and the selected hits were tested through cell-based assays in the NAPRT-proficient OVCAR-5 ovarian cell line and on the recombinant hNAPRT. We found different chemotypes that efficiently inhibit the enzyme in the micromolar range concentration and for which direct engagement with the target was verified by differential scanning fluorimetry. Of note, the therapeutic potential of these compounds was evidenced by a synergistic interaction between the NAMPT inhibitor FK866 and the new NAPRTi in terms of decreasing OVCAR-5 intracellular NAD levels and cell viability. For example, compound IM29 can potentiate the effect of FK866 of more than two-fold in reducing intracellular NAD levels. These results pave the way for the development of a new generation of human NAPRTi with anticancer activity

Multivariable time-dependent analysis of the impact of azacitidine in patients with lower-risk myelodysplastic syndrome and unfavorable specific lower-risk score

Scoring systems for lower-risk myelodysplastic syndrome (LR-MDS) recognize patients with a poorer than expected outcome. This study retrospectively analyzes the role of azacitidine in LR-MDS with adverse risk score and compared to an historical cohort treated with best supportive care or erythropoiesis-stimulating agents. Overall response to AZA was 40%. One and 2-year probabilities of survival were 62% and 45% for AZA vs. 25% and 11% (P=10(-4)). In a multivariable time-dependent analysis, response to AZA (CR/PR/HI) was associated with an improved survival (HR=0.234, 95% CI, 0.063-0.0863; P=0.029). Thrombocytopenia (<50 × 10(9)L(-1)) is confirmed as an adverse parameter in LR-MDS (HR=1.649, 95% CI, 1.012-2.687; P=0.045)