Optical modelling of a layered photovoltaic device with a polyfluorene derivative/fullerene as the active layer

Here we report on optical modelling of organic photovoltaic devices having a layered geometry, with polyfluorene-copolymer as the active material and C₆₀ as the acceptor. Thin film theory in a matrix formalism enables analysis of the impact of reflection and interference on the optical electric field. The model allows us to predict an optimal C₆₀ thickness where concern has been taken for light being both polychromatic and distributed according to solar irradiation. Fundamental for light–matter interaction is the dielectric function. We have extracted it for two variants of a new polyfluorene copolymer, PFDTBT, from UV via visible to the nearest infrared, using spectroscopic ellipsometry (SE). n is found to be relatively high with a max-value above 2.1. The process of spin coating induces anisotropy in the polymer film.     

Crystallization of Nano‐Calcium Carbonate: The Influence of Process Parameters

Precipitated calcium carbonate was synthesized by carbonation of calcium hydroxide in the presence and absence of ultrasound (conventional stirring) at atmospheric as well as at elevated pressures and different initial concentrations of Ca(OH)₂. Spherical morphology of the formed calcite was favored at high Ca(OH)₂ concentrations and low CO₂ pressures. The presence of ultrasound did not show any influence on the reaction rate in case of efficient mixing. A small increase of the reaction rate was observed at lower CO₂ pressures. Elevated pressures in combination with ultrasound did not lead to notable changes of reaction rate or particle morphology.     

Populationsbilanzmodellierung mit einem Mehrphasen‐CFD‐Code und vergleichende Visualisierung

The Euler‐Euler multiphase approach multiphaseEulerFoam is extended by implementation of several population balance models to describe the variation of the dispersed phase bubble size. The different models are compared with each other and with experimental data. A new approach is developed, which allows, in addition to the representation of the bubble size, an accurate visualization of the bubble shape based on the Eötvös and Reynolds number as well as position probability and number of bubbles and therefore simplifies the comparison between simulation and experiment.     

Cytotoxic effects of extract of Acmella oleraceae (Jambú) in Rhipicephalus microplus females ticks

The present study analyzed the effects of different concentrations of the hexane extract of A. oleraceae (HEAO) (Jambú) on the germ cells of semi‐engorged Rhipicephalus microplus female ticks, through a morpho‐histological study, evaluating the effectiveness of the extract in the genesis of the individuals. To perform this analysis, 100 semi‐engorged females were divided into five groups with 20 individuals each: groups I and II, respectively constituted by distilled water control and 50% ethanol + 1% DMSO, and groups III, IV, and V constituted by treatment with HEAO in the concentrations of 12.5, 25.0 and 50.0 mg/mL, respectively. All the ticks were immersed in the different concentrations of the extract or in distilled water for 5 minutes, dried and conditioned in BOD incubator for 7 days. The individuals of the treatment groups revealed the action of this extract showing alterations in the germ cells of the females from the different groups when compared with those from the groups I and II (control groups). These alterations were mainly related to the size and shape of the oocytes; number of yolk granules; presence, number, size and location of vacuoles in the cytoplasm of all the germ cells; and the presence of nuclear alterations in these cells as well. Thus, it was demonstrated that the concentrations of HEAO affected the germ cells of R. microplus ticks. The effects of the extract are similar to those caused by renowned and efficient chemical products used to control these ticks. Microsc. Res. Tech. 79:744–753, 2016. © 2016 Wiley Periodicals, Inc.     

Cytotoxic effects of permethrin on mouse liver and spleen cells

This study analyzed the histopathological and histochemical effects of different dosages of permethrin on liver and spleen cells of mice, in order to evaluate the toxic potential of this substance and the possible impairments that this chemical causes in different tissues of nontarget organisms (laboratorial conditions). The results showed that permethrin caused severe alterations in the liver cells, reducing the size of the nuclei and causing hydropic degeneration of the hepatocytes, in addition to stimulating the proliferation of Kupffer cells, altered the amount of proteins, polysaccharides, lipids, and vacuoles in the cytoplasm of the hepatocytes and congested the hepatic capillaries. As for the spleen of the treated mice, no alterations were observed in the morphology in relation to the control group, what would suggest that the spleen would continue performing its functions, without suffering morphological alterations even in the presence of the toxic agent.     

Influencing hardness and wear during the dynamic tempered microinjection molding process by considering isothermal holding time

For semicrystalline thermoplastic parts it is well known that increasing isothermal holding temperature can affect inner component properties, respectively, crystalline structure (e.g., morphology, degree of crystallization, crystal modification, etc.) and, therefore, resulting global component properties such as hardness and wear. Nevertheless, in literature there is no explicit focus on the effect of isothermal holding time during dynamically tempered injection molding process. In this article, semicrystalline microcomponents have been injection molded by varying isothermal holding time within the material's crystallization temperature area. As materials, POM‐C, as a material with relatively high crystallization kinetic, and PA 12, as a material with medium crystallization kinetic, were used. To evaluate the effects on hardness and wear, nanoindentation measurements as well as pin‐on‐disc wear tests were performed. Results show that for fast crystallizing POM‐C an isothermal holding step has no significant influence on inner component and resulting global component properties. For slower crystallizing PA 12, however, the morphology and the degree of crystallization could be influenced and, as a result, hardness could be increased by 21% while wear could be reduced by 30%. POLYM. ENG. SCI., 57:121–128, 2017. © 2016 Society of Plastics Engineers     

Nanostructured Antimony‐Doped Tin Oxide Layers with Tunable Pore Architectures as Versatile Transparent Current Collectors for Biophotovoltaics

Nanostructured transparent conducting oxide (TCO) layers gain increasing importance as high surface area electrodes enabling incorporation of functional redox species with high loading. The fabrication of porous TCO films, namely, antimony‐doped tin oxide (ATO), is reported using the self‐assembly of preformed ATO nanocrystals with poly(ethylene oxide‐b‐hexyl acrylate) (PEO‐b‐PHA) block copolymer. The high molar mass of the polymer and tunable solution processing conditions enable the fabrication of TCO electrodes with pore sizes ranging from mesopores to macropores. Particularly notable is access to uniform macroporous films with a nominal pore size of around 80 nm, which is difficult to obtain by other techniques. The combination of tunable porosity with a large conducting interface makes the obtained layers versatile current collectors with adjustable performance. While all the obtained electrodes incorporate a large amount of small redox molecules such as molybdenum polyoxometalate, only the electrodes with sufficiently large macropores are able to accommodate high amounts of bulky photoactive photosystem I (PSI) protein complexes. The 11‐fold enhancement of the current response of PSI modified macroporous ATO electrodes compared to PSI on planar indium tin oxide (ITO), makes this type of electrodes promising candidates for the development of biohybrid devices.     

Speedy component resolution: an improved tool for processing diffusion-ordered spectroscopy data

Diffusion-based NMR techniques (e.g., diffusion-ordered spectroscopy, DOSY), which can be used to distinguish between the signals of different components of a mixture, are steadily gaining in popularity. When processing data from a DOSY experiment it is often desirable to reconstruct the spectra of individual components; here, multivariate methods that take advantage of the covariance between the resonances of a given component can often be advantageous. This paper presents a minor variation on the established CORE method, speedy component resolution (SCORE), that gives a major improvement in performance. In common with CORE it can use any experimental sampling scheme and is adaptable to different experimental decay shapes, but unlike CORE it is very fast and relatively insensitive to starting guesses. The method is demonstrated on a mixture of quinine, geraniol, and camphene in deuteriated methanol, where all four component spectra can be extracted in less than 15 s.