Regional Integration in West Africa - Are Countries Diverging?

The author examines reasons for divergence of GDP per capita among the members of ECOWAS, a RIA in West Africa of 15 members. Also, WAEMU, another RIA in West Africa, is analyzed although to a smaller extent than ECOWAS. Mainly consequences of trade diversion and agglomeration effects are considered. An analysis of the dispersion of GDP per capita between the members is carried out to find evidence for the predicted divergence among the members. The author concludes that there are reasons to believe that regional integration in West Africa is causing divergence of GDP per capita. However, since intra-community trade constitutes only a minor share of total trade of the members of ECOWAS, it is difficult to assess the effects of regional integration

Селянознавчі дослідження в контексті формування концепції Української революції 1917-1921 рр.

У статті визначені структурні складові розробки селянознавчої проблематики в контексті формування наукової концепції історії Української революції 1917-1921 рр

Three-hour blood culture detection of Streptococcus pneumoniae

Autore

Intermodulation electrostatic force microscopy for imaging surface photo-voltage

We demonstrate an alternative to Kelvin Probe Force Microscopy for imaging surface potential. The open-loop, single-pass technique applies a low-frequency AC voltage to the atomic force microscopy tip while driving the cantilever near its resonance frequency. Frequency mixing due to the nonlinear capacitance gives intermodulation products of the two drive frequencies near the cantilever resonance, where they are measured with high signal to noise ratio. Analysis of this intermodulation response allows for quantitative reconstruction of the contact potential difference. We derive the theory of the method, validate it with numerical simulation and a control experiment, and we demonstrate its utility for fast imaging of the surface photo-voltage on an organic photo-voltaic material.Comment: 4 pages, 3 figures, peer-reviewed, preprin

Trapping light with micro lenses in thin film organic photovoltaic cells.

We demonstrate a novel light trapping configuration based on an array of micro lenses in conjunction with a self aligned array of micro apertures located in a highly reflecting mirror. When locating the light trapping element, that displays strong directional asymmetric transmission, in front of thin film organic photovoltaic cells, an increase in cell absorption is obtained. By recycling reflected photons that otherwise would be lost, thinner films with more beneficial electrical properties can effectively be deployed. The light trapping element enhances the absorption rate of the solar cell and increases the photocurrent by as much as 25%. (C) 2008 Optical Society of Americ

Organic solar cells based on non-fullerene acceptors.

Organic solar cells (OSCs) have been dominated by donor:acceptor blends based on fullerene acceptors for over two decades. This situation has changed recently, with non-fullerene (NF) OSCs developing very quickly. The power conversion efficiencies of NF OSCs have now reached a value of over 13%, which is higher than the best fullerene-based OSCs. NF acceptors show great tunability in absorption spectra and electron energy levels, providing a wide range of new opportunities. The coexistence of low voltage losses and high current generation indicates that new regimes of device physics and photophysics are reached in these systems. This Review highlights these opportunities made possible by NF acceptors, and also discuss the challenges facing the development of NF OSCs for practical applications

Morphology, Temperature, and Field Dependence of Charge Separation in High-Efficiency Solar Cells Based on Alternating Polyquinoxaline Copolymer

Charge separation and recombination are key processes determining the performance of organic optoelectronic devices. Here we combine photoluminescence and photovoltaic characterisation of organic solar cell devices with ultrafast multi-pulse photocurrent spectroscopy to investigate charge generation mechanisms in the organic photovoltaic devices based on a blend of an alternating polyquinoxaline copolymer with fullerene. The combined use of these techniques enables the determination of the contributions of geminate and bimolecular processes to the solar cell performance. We observe that charge separation is not a temperature-activated process in the studied materials. At the same time, the generation of free charges shows a clear external-field and morphology dependence. This indicates that the critical step of charge separation involves the non-equilibrium state that is formed at early times after photoexcitation, when the polaronic localisation is not yet complete. This work reveals new aspects of molecular level charge dynamics in the organic light-conversion systems.We thank Maxim Pschenichnikov for useful discussions, and Ergang Wang for providing TQ1. This work was supported by the Netherlands Organization for Scientific Research (NWO) through the “Stichting voor Fundamenteel Onderzoek der Materie” (FOM). A.A.B. also acknowledges a VENI grant from NWO. A.A.B. is currently a Royal Society University Research Fellow. Photovoltaics research at Linköping was supported by the Swedish Research Council (VR), the European Commission Marie Skłodowska-Curie actions, the Swedish Energy Agency, and the Knut and Alice Wallenberg foundation (KAW).This is the author accepted manuscript. The final version is available from the American Chemical Society via http://dx.doi.org/10.1021/acs.jpcc.5b1080

Charge Carrier Extraction by Linearly Increasing Voltage:Analytic framework and ambipolar transients

Up to now the basic theoretical description of charge extraction by linearly increasing voltage (CELIV) is solved for a low conductivity approximation only. Here we present the full analytical solution, thus generalize the theoretical framework for this method. We compare the analytical solution and the approximated theory, showing that especially for typical organic solar cell materials the latter approach has a very limited validity. Photo-CELIV measurements on poly(3-hexyl thiophene-2,5-diyl):[6,6]-phenyl-C61 butyric acid methyl ester based solar cells were then evaluated by fitting the current transients to the analytical solution. We found that the fit results are in a very good agreement with the experimental observations, if ambipolar transport is taken into account, the origin of which we will discuss. Furthermore we present parametric equations for the mobility and the charge carrier density, which can be applied over the entire experimental range of parameters.Comment: 8 pages, 5 figure

Психолого-педагогічні умови формування просоціальної поведінки у дітей молодшого шкільного віку

(uk) У статті формування просоціальної поведінки розглядається як керована соціалізація особистості, проаналізовані передумови розгляду питання щодо стадіальності становлення просоціальної поведінки в онтогенезі. Обґрунтовані та систематизовані психолого-педагогічні умови, що прискорюють процес формування суспільно корисної поведінки в молодшому шкільному віці.(ru) В статье формирования просоциального поведения рассматривается как управляемая социализация личности, проанализированы предпосылки рассмотрения вопроса о стадиальности становления просоциального поведения в онтогенезе. Обоснованы и систематизированы психолого-педагогические условия, которые могут ускорить процес формирования общественно полезного поведения в младшем школьном возрасте