Quantifying the role of interfacial width on intermolecular charge recombination in block copolymer photovoltaics

Block copolymers have the potential to control the interfacial and mesoscopic structure in the active layer of organic photovoltaics and consequently enhance device performance beyond systems which rely on physical mixtures. When utilized as the active layer, poly(3‐hexylthiophene‐2,5‐diyl)‐block‐poly((9,9‐bis‐(2‐octyldodecyl)fluorene‐2,7‐diyl)‐alt‐(4,7‐di(thiophene‐2‐yl)?2,1,3‐benzothiadiazole)?5′,5″‐diyl) donor–acceptor block copolymers have recently demonstrated 3% power conversion efficiencies in devices. Nevertheless, the role of the interfacial structure on charge transfer processes remains unclear. Using density functional theory, we examined charge transfer rate constants in model interfaces of donor–acceptor block copolymers. Our results demonstrate that intermolecular charge recombination can depend on the interfacial breadth, where sharp interfaces (ca. 1 nm) suppress intermolecular charge recombination by orders of magnitude. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1224–1230     

A method based on PSO and granular computing of linguistic information to solve group decision making problems defined in heterogeneous contexts

Group decision making is a type of decision problem in which multiple experts acting collectively, analyze problems, evaluate alternatives, and select a solution from a collection of alternatives. As the natural language is the standard representation of those concepts that humans use for communication, it seems natural that they use words (linguistic terms) instead of numerical values to provide their opinions. However, while linguistic information is readily available, it is not operational and thus it has to be made usable though expressing it in terms of information granules. To do so, Granular Computing, which has emerged as a unified and coherent framework of designing, processing, and interpretation of information granules, can be used. The aim of this paper is to present an information granulation of the linguistic information used in group decision making problems defined in heterogeneous contexts, i.e., where the experts have associated importance degrees reflecting their ability to handle the problem. The granulation of the linguistic terms is formulated as an optimization problem, solved by using the particle swarm optimization, in which a performance index is maximized by a suitable mapping of the linguistic terms on information granules formalized as sets. This performance index is expressed as a weighted aggregation of the individual consistency achieved by each expert.     

Transesterification of ethyl butyrate with methanol using MgO/CaO catalysts

A series of mixtures of MgO/CaO with different Mg/Ca molar ratios (between 3 and 15), as well as the corresponding pure oxides, was prepared by the coprecipitation method in a basic medium and subsequent calcination. Their textural and structural characterization was carried out by using XRD, FT-IR, SEM and N₂ sorption at 77 K. The alkalinity was studied by CO₂-TPD and catalytic decomposition of 2-propanol. The MgCa oxides obtained after calcination at 1073 K exhibit X-ray diffraction patterns with clearly visible signals corresponding to crystalline CaO and MgO. Textural properties are improved by the presence of Mg, with the porosity increased and the particle sizes decreased with respect to pure CaO. FT-IR spectroscopy reveals the presence of surface carbonate. These catalysts are active in the transesterification of ethyl butyrate with methanol at 333 K and atmospheric pressure, a model reaction to evaluate the potential of these basic catalysts in triglycerides transesterification for biodiesel production. The highest activity was found for a Mg:Ca molar ratio of 3, with conversion close to 60%, whereas MgO was inactive. Moreover, lixiviation of the active phase was not observed thus excluding the contribution of the homogeneous catalysis to the studied transesterification process.     

Truncating and chamfering diagrams of regular polyhedra

Truncating the vertex and chamfering the edges of a polyhedron is the classic way to obtain Archimedean polyhedra taking a Platonic solid as the starting point. We have considered the set of polyhedra obtained by this method and have found singular diagrams that show a special relation between these Archimedean polyhedra.     

Structural, Spectroscopic, and Thermal Behaviour of Bis -(thiosaccharinate)-aqua-cadmium(II)

 The crystal structure of the title complex, [Cd(tsac)₂(H₂O)], has been determined by single crystal X-ray diffraction methods. It crystallizes in the monoclinic space group C2/c (a = 12.236(3), b = 8.919(3), c = 16.655(3) ?, β = 96.18(2)°, Z = 4). The molecular structure was solved from 1705 independent reflections with I > σ(I) and refined to R ₁ = 0.0489. Infrared and Raman spectra of the complex were recorded and are briefly discussed. Its thermal behaviour was investigated by thermogravimetry and differential thermal analysis.