Ester-functionalized poly(3-alkylthiophene) copolymers: Synthesis,physicochemical characterization and performance in bulk heterojunction organic solar cells

The introduction of functional moieties in the donor polymer (side chains) offers a potential pathway toward selective modification of the nanomorphology of conjugated polymer:fullerene active layer blends applied in bulk heterojunction organic photovoltaics, pursuing morphology control and solar cell stability. For this purpose, two types of poly(3-alkylthiophene) random copolymers, incorporating different amounts (10/30/50%) of ester-functionalized side chains, were efficiently synthesized using the Rieke method. The solar cell performance of the functionalized copolymers was evaluated and compared to the pristine P3HT:PCBM system. It was observed that the physicochemical and opto-electronic characteristics of the polythiophene donor material can be modified to a certain extent via copolymerization without (too much) jeopardizing the OPV efficiency, as far as the functionalized side chains are introduced in a moderate ratio (<30%) and that preference is given to side chains with a small molar volume. A range of complementary techniques – UV–Vis spectroscopy, (modulated temperature) differential scanning calorimetry, transmission electron microscopy and X-ray diffraction analysis – indicated that variations in polymer crystallinity, while maintaining a high level of regioregularity, are probably the main factor responsible for the observed differences.     

Effect of peclet parameters of reacting components on their concentrations in consecutive reaction

The method of using two indicators with different molecular diffusion coefficients has been suggested, which allows one to estimate the dependence of the structure of flows and Peclet number of reacting components vs. the hydrodynamic mode of their flow in reactors. The mathematical model has been considered at various Peclet parameters on reacting components for the first-order consecutive reaction with new boundary conditions and the results of calculations have been compared with a standard one-parameter model.     

Measuring institutional research productivity for the life sciences: the importance of accounting for the order of authors in the byline

Accurate measurement of institutional research productivity should account for the real contribution of the research staff to the output produced in collaboration with other organizations. In the framework of bibliometric measurement, this implies accounting for both the number of co-authors and each individual’s real contribution to scientific publications. Common practice in the life sciences is to indicate such contribution through the order of author names in the byline. In this work, we measure the distortion introduced to university-level bibliometric productivity rankings when the number of co-authors or their position in the byline is ignored. The field of observation consists of all Italian universities active in the life sciences (Biology and Medicine). The analysis is based on the research output of the university staff over the period 2004–2008. Based on the results, we recommend against the use of bibliometric indicators that ignore co-authorship and real contribution of each author to research outputs.     

The stretch zone of automotive steel sheets

The paper deals with an experimental determination of the stretch zone dimensions in the notch tip in thin steel sheets. The stretch zone dimensions depend on steel grade, on the rolling direction as well as on the loading rate. Stretch zones were observed and measured on three steel grades. Fracture area and stretch zones were analysed by SEM. Stable crack growth was monitored by videoextensometry techniques on CT (Compact Tension) specimens. Specimens were loaded under two loading rates by eccentric tension, whereby the deformation in the notch surrounding area was recorded using a non-contact measurement–videoextensometry technique. Linear relation between the stretch zone dimensions was determined.     

Structured estimation of tire forces and the ground slope using SM observers

In agricultural context, the principal cause of serious accidents for all-terrain vehicles(ATVs) is rollover. The most important parameters related to this risk is the ground slope. In this paper, we propose a structured observer to estimate the system states and the longitudinal tire forces using only wheel angular velocities measurement. The robust estimation is based on a second order sliding mode observer. This estimation is then used to build up a ground slope estimation. The algorithm is composed by two cascaded estimators. This structured estimation is then applied to the model of an agricultural vehicle G7(GregoireTM) integrated in the driving simulation environment SCANeRTM-Studio.     

Shaking Table Test and Analysis of Reinforced Concrete Frame with Steel Shear Wall with Circular Opening and Slit Damper

International Journal of Steel Structures - Earthquakes of 5.8 and 5.4 Richter scale recently occurred one after another in Korea, changing the Korean peninsula from an earthquake safe zone but...     

Effectiveness and Physical Characteristics of Machining Fluid

The effectiveness of four water-based machining fluids is studied as a function of their physical properties. Mathematical formulas are derived for optimal selection of machining fluids.