Impact of composition and morphology on the optical properties of Si-NC/P3HT thin films processed from solution

Blends of Si nanocrystals (Si-NCs) and organic semiconductors are promising materials for new optical and electronic devices processed from solutions. Here, we study how the optical properties of composite films containing Si-NCs and the organic semiconductor poly(3-hexylthiophene) (P3HT) are influenced by the composition and morphology resulting from different solution-processing parameters and different solvents used dichlorobenzene vs. chloroform). The optical spectra of the hybrid films are described using a simple phenomenological model, with which we can discern the contribution of each material in the films to the optical properties. From this analysis, we obtain quantitative information about the composition and morphology of the hybrid nanostructured films, which otherwise would be obtained from more demanding microscopy and spectroscopy techniques. For the case of the Si-NC/P3HT blend, we find that in films deposited from dichlorobenzene solutions the Si-NCs contribute sizably to light absorption.     

Histone deacetylase inhibitors: structure-based modeling and isoform-selectivity prediction

An enhanced version of comparative binding energy (COMBINE) analysis, named COMBINEr, based on both ligand-based and structure-based alignments has been used to build several 3-D QSAR models for the eleven human zinc-based histone deacetylases (HDACs). When faced with an abundance of data from diverse structure-activity sources, choosing the best paradigm for an integrative analysis is difficult. A common example from studies on enzyme-inhibitors is the abundance of crystal structures characterized by diverse ligands complexed with different enzyme isoforms. A novel comprehensive tool for data mining on such inhomogeneous set of structure-activity data was developed based on the original approach of Ortiz, Gago, and Wade, and applied to predict HDAC inhibitors' isoform selectivity. The COMBINEr approach (apart from the AMBER programs) has been developed to use only software freely available to academics.     

Deposition of Polyacrylic Acid Films by Means of an Atmospheric Pressure Dielectric Barrier Discharge

The present work describes the plasma polymerisation of acrylic acid at atmospheric pressure. The influence of two operating parameters (monomer concentration and discharge power) on the properties of the deposited films is investigated. Results show that at a monomer concentration of 2.5 ppm and a discharge power of 9.5 W, the monomer is only slightly fragmented leading to a high amount of carboxylic acid groups on the deposited films. In contrast, when monomer concentration is decreased or discharge power increased, the incidence of monomer fragmentation processes is higher, leading to a lower amount of carboxylic acid groups on the films. This behaviour can be explained by a higher energy amount available per monomer molecule at low monomer concentrations and high discharge powers and a higher flux of positive ions attacking the surface at high discharge powers. Taking into account these results, it can be concluded that the deposition parameters should be carefully selected in order to preserve the stability of the monomer and thus obtain coatings with high carboxylic acid densities.     

Application of the mutual-interaction method to a class of two-scatterer systems: I. Two discrete scatterers

In a recent paper we developed a formalism that fully accommodates the mutual interactions among scatterers separable by parallel planes. The total fields propagating away from these planes are the unknowns of a system of difference equations. Each scatterer is characterized by a scattering function that expresses the scattered wave amplitude as a function of the incident and scattered wavevectors for a unit-amplitude plane wave scattered from the object in isolation. This function can be derived completely from the scattered far field with the help of analytic continuation. For a two-scatterer system the mutual-interaction equations reduce to a single Fredholm integral equation of the second kind. It turns out that analytic solutions are tractable for those scattering functions that are Dirac deltas or a sum of products of separable functions of the incident and scattered wavevectors. Scattering functions for planes and isotropic scatterers, as well as electric and magnetic dipoles all possess this property and are considered. The exact scattering functions agree with results obtained by analytic continuation. This paper consists of two parts. Part I derives analytic solutions for two discrete scatterers (isotropic scatterers. electric dipoles, magnetic dipoles). Part II is devoted to scattering from an object (isotropic or dipole scatterer) near an interface separating two semi-infinite uniforn-media. Because the results in this paper are exact, the effects of near-field interactions can be assessed. The forms of the scattering solutions can be adapted to objects that are both radiating and scattering.     

Liquid-crystalline quinoline derivatives

A number of novel liquid crystals have been synthesized. 2-Phenylquinolines with alkyl or alkoxyl substituents in positions 6 and 4' show a texture typical of nematic mesophases and are characterized by a greater thermal stability than Schiff bases bearing the same substituents. The possibility of lowering the melting temperatures by means of eutectic mixtures is discussed.     

Reaction of 2-arylazo-2, 5-dimethyl-3(2H)-furanones with ammonia. Preparation of β-acetyl-β-(3-amino-2-butenoyl) arylhydrazines.

Ring opening of 2-arylazo-2,5-dimethyl-3(2H)-furanones ($\text{1a–d}$) with ammonia leads to previously unknown β-acetyl-β-(3-amino-2-butenoyl)arylhydrazines ($\text{3a–d}$). The reaction mechanism is discussed.     

Molecular dynamics simulation on devitrification: isothermal devitrification and thermodynamics of PbF2 glasses

The vitrification and devitrification features of lead fluoride are investigated by means of molecular dynamic simulations. The influence of heating rate on the devitrification temperature as well as the dependence of the glass properties on its thermal history, i.e., the cooling rate employed, is identified. As expected, different glasses are obtained when the cooling rates differ. Diffusion coefficient analysis during heating of glass and crystal, indicates that the presence of defects on the glassy matrix favors the transition processes from the ionic to a superionic state, with high mobility of fluorine atoms, responsible for the high anionic conduction of lead fluoride. Nonisothermal and isothermal devitrification processes are simulated in glasses obtained at different cooling rates and structural organizations occurring during the heat treatments are clearly observed. When a fast cooling rate is employed during the glass formation, the devitrification of a single crystal (limited by the cell dimensions) is observed, while the glass obtained with slower cooling rate, allowing relaxations and organization of various regions on the glass bulk during the cooling process, devitrifies in more than one crystalline plane.     

Trust and relational capital

Trust can be viewed at the same time as an instrument both for an agent selecting the right partners in order to achieve its own goals, and for an agent of being selected from other potential partners in order to establish with them a cooperation/collaboration and to take advantage from the accumulated trust. In this paper we will analyze trust as the agents’ relational capital. Starting from the classical dependence network with potential partners, we introduce the analysis of what it means for an agent to be trusted and how this condition could be strategically used from it for achieving its own goals, that is, why it represents a form of power. The idea of taking another agent’s point of view is especially important if we consider the amount of studies in social science that connect trust with social capital related issues. Although there is a big interest in literature about ‘social capital’ and its powerful effects on the wellbeing of both societies and individuals, often it is not clear enough what is it the object under analysis. Individual trust capital (relational capital) and collective trust capital not only should be disentangled, but their relations are quite complicated and even conflicting. To overcome this gap, we propose a study that first attempts to understand what trust is as capital of individuals. In which sense “trust” is a capital. How this capital is built, managed and saved. In particular, how this capital is the result of the others’ beliefs and goals. Then we aim to analytically study the cognitive dynamics of this object.