Weak lensing of large scale structure in the presence of screening

A number of alternatives to general relativity exhibit gravitational screening in the non-linear regime of structure formation. We describe a set of algorithms that can produce weak lensing maps of large scale structure in such theories and can be used to generate mock surveys for cosmological analysis. By analysing a few basic statistics we indicate how these alternatives can be distinguished from general relativity with future weak lensing surveys.Comment: 25 pages, 7 figures, accepted by JCAP. v2: references updat

Spectroscopic and interferometric signatures of magnetospheric accretion in young stars

Methods. We use the code MCFOST to solve the non-LTE problem of line formation in non-axisymmetric accreting magnetospheres. We compute the Br{\gamma} line profile originating from accretion columns for models with different magnetic obliquities. We also derive monochromatic synthetic images of the Br{\gamma} line emitting region across the line profile. This spectral line is a prime diagnostics of magnetospheric accretion in young stars and is accessible with the long baseline near-infrared interferometer GRAVITY installed at the ESO Very Large Telescope Interferometer. Results. We derive Br{\gamma} line profiles as a function of rotational phase and compute interferometric observables, visibilities and phases, from synthetic images. The line profile shape is modulated along the rotational cycle, exhibiting inverse P Cygni profiles at the time the accretion shock faces the observer. The size of the line's emission region decreases as the magnetic obliquity increases, which is reflected in a lower line flux. We apply interferometric models to the synthetic visibilities in order to derive the size of the line-emitting region. We find the derived interferometric size to be more compact than the actual size of the magnetosphere, ranging from 50 to 90\% of the truncation radius. Additionally, we show that the rotation of the non-axisymmetric magnetosphere is recovered from the rotational modulation of the Br{\gamma}-to-continuum photo-centre shifts, as measured by the differential phase of interferometric visibilities

Air-Stable Benzimidazoline n-Type Dopants for Conductive Host Materials with Low Electron Affinities

Nowadays a growing interest is devoted to molecular reductants for solution-processable organic semiconductors such as organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), thermoelectric generators (TEGs), organic field-effect transistors (OFETs), and circuitry in which they can increase the conductivity, reduce bulk ohmic losses and/or decrease carrier-injection barriers.[1] They can also modulate the work function (WF) of inorganic electrode materials and push the performance of inverted perovskite solar cell by boosting the conductivity of PCBM type ETMs. However, the availability of high-performance and airstable solution-processable n-doped materials remains limited, primarily due to the low electron affinity of n-type materials that strongly restricts the n-doping level. Benzimidazoline-based reductants (Figure1) have recently emerged as efficient and air-stable n-type dopants in electron transporting materials (ETMs) to increase electrical conductivities.[2] Hence we designed and synthesized a series of Benzimidazoline based compounds as air-stable n-dopants and their doping abilities have been surveyed by analysing the electron conductivity trend of organic semiconductors. Moreover an in-depth study of their electrochemical characteristics have been carried out and their molecular orbital energy levels investigated. The most efficient n-doping molecules are intended to largescale, printed electronics for energy-harvesting and storage applications

Second Order Nonlinear Optical Properties of 4-Styrylpyridines Axially Coordinated to A4 ZnII Porphyrins: A Comparative Experimental and Theoretical Investigation

In this research, two 4-styrylpyridines carrying an acceptor \u2013NO2 (L1) or a donor \u2013NMe2 group (L2) were axially coordinated to A4 ZnII porphyrins displaying in 5,10,15,20 meso position aryl moieties with remarkable electron withdrawing properties (pentafluorophenyl (TFP)), and with moderate to strong electron donor properties (phenyl (TPP) < 3,5-di-tert-butylphenyl (TBP) < bis(4-tert-butylphenyl)aniline) (TNP)). The second order nonlinear optical (NLO) properties of the resulting complexes were measured in CHCl3 solution by the Electric-Field-Induced Second Harmonic generation technique, and the quadratic hyperpolarizabilities \u3b2\u3bb were compared to the Density Functional Theory (DFT)-calculated scalar quantities \u3b2||. Our combined experimental and theoretical approach shows that different interactions are involved in the NLO response of L1- and L2-substituted A4 ZnII porphyrins, suggesting a role of backdonation-type mechanisms in the determination of the negative sign of Electric-Field-Induced Second Harmonic generation (EFISH) \u3b2\u3bb, and a not negligible third order contribution for L1-carrying complexes

Capping agent effect on Pd-supported nanoparticles in the hydrogenation of furfural

The catalytic performance of a series of 1 wt % Pd/C catalysts prepared by the sol-immobilization method has been studied in the liquid-phase hydrogenation of furfural. The temperature range studied was 25\u201375 \ub0C, keeping the H2 pressure constant at 5 bar. The effect of the catalyst preparation using different capping agents containing oxygen or nitrogen groups was assessed. Polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and poly (diallyldimethylammonium chloride) (PDDA) were chosen. The catalysts were characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The characterization data suggest that the different capping agents affected the initial activity of the catalysts by adjusting the available Pd surface sites, without producing a significant change in the Pd particle size. The different activity of the three catalysts followed the trend: PdPVA/C > PdPDDA/C > PdPVP/C. In terms of selectivity to furfuryl alcohol, the opposite trend has been observed: PdPVP/C > PdPDDA/C > PdPVA/C. The different reactivity has been ascribed to the different shielding effect of the three ligands used; they influence the adsorption of the reactant on Pd active sites

An improved synthesis, crystal structures, and metallochromism of salts of [Ru(tolyl-terpy)(CN)(3)](-)

The previously reported complex [Ru(ttpy)(CN)(3)] [ttpy = 4'(p-tolyl)-2,2':6',2"-terpyridine] is conveniently synthesised by reaction of ttpy with Ru(dmso)(4)Cl-2 to give [Ru(ttpy)(dmso)Cl-2], which reacts in turn with KCN in aqueous ethanol to afford [Ru(ttpy)(CN)(3)] which was isolated and crystallographically characterised as both its (PPN)(+) and K+ salts. The K+ salt contains clusters containing three complex anions and three K+ cations connected by end-on and side-on cyanide ligation to the K+ ions. The solution speciation behaviour of [Ru(ttpy)(CN)(3)] was investigated with both Zn2+ and K+ salts in MeCN, a solvent sufficiently non-competitive to allow the added metal cations to associate with the complex anion via the externally-directed cyanide lone pairs. UV-Vis spectroscopic titration of (PPN)[Ru(ttpy)(CN)(3)] with Zn(ClO4)(2) showed a blue shift of 2900 cm (1) in the (MLCT)-M-1 absorption manifold due to the ` metallochromism' effect; a series of distinct binding events could be discerned corresponding to formation of 4:1, 1:1 and then 1:3 anion: cation adducts, all with high formation constants, as the titration proceeded. In contrast titration of (PPN)[Ru(ttpy)(CN)(3)] with the more weakly Lewis-acidic KPF6 resulted in a much smaller blue-shift of the 1MLCT absorptions, and the titration data corresponded to formation of 1:1 and then 2: 1 cation: anion adducts with weaker stepwise association constants of the order of 10(4) and then 10(3) M (1). Although association of [Ru(ttpy)(CN)(3)] resulted in a blue-shift of the (MLCT)-M-1 absorptions, the luminescence was steadily quenched, as raising the (MLCT)-M-3 level makes radiationless decay via a lowlying (MC)-M-3 state possible. (C) 2010 Elsevier B. V. All rights reserved

Efficient sunlight harvesting by A4 b-pyrrolic substituted ZnII porphyrins : a mini-review

Dye-Sensitized Solar Cells (DSSCs) are a highly promising alternative to conventional photovoltaic silicon-based devices, due to the potential low cost and the interesting conversion efficiencies. A key-role is played by the dye, and porphyrin sensitizers have drawn great interest because of their excellent light harvesting properties mimicking photosynthesis. Indeed, porphyrins are characterized by strong electronic absorption bands in the visible region up to the near infrared and by long-lived \u3c0* singlet excited states. Moreover, the presence of four meso and eight \u3b2-pyrrolic positions allows a fine tuning of their photoelectrochemical properties through structural modification. Trans-A2BC push-pull ZnII porphyrins, characterized by a strong and directional electron excitation process along the push-pull system, have been extensively investigated. On the other hand, A4 \u3b2-pyrrolic substituted tetraaryl ZnII porphyrins, which incorporate a tetraaryl porphyrinic core as a starting material, have received lower attention, even if they are synthetically more attractive and show several advantages such as a more sterically hindered architecture and enhanced solubility in most common organic solvents. The present contribution intends to review the most prominent A4 \u3b2-substituted ZnII porphyrins reported in the literature so far for application in DSSCs, focusing on the strategies employed to enhance the light harvesting capability of the dye and on a comparison with meso-substituted analogs

Machine learning aplicado a remote sensing: aplicaciones en gobernanza digital para el desarrollo sustentable

El presente trabajo muestra las problemáticas abordadas mediante tecnologías de Machine Learning aplicadas a Remote Sensing, las que pueden servir de soporte a la gobernanza digital para el desarrollo sustentable. Para ello se realiza una revisión bibliográfica de la utilización de estas dos tecnologías con el fin de mostrar cuáles son los avances alcanzados en el área, en qué se está trabajando y cuáles son las aplicaciones relacionadas con la gobernanza electrónica para el desarrollo sustentable.Trabajo presentado por el Instituto de Investigación y Transferencia en Tecnología (ITT