Organic Solar Cells: Problems and Perspectives

For photovoltaic cells to convert solar into electric energy is probably the most interesting research challenge nowadays. A good efficiency of these devices has been obtained by using inorganic semiconductor materials. On the other hand, manufacture processes are very expensive in terms of both materials and techniques. For this reason organic-based photovoltaic (OPV) cells are attracting the general attention because of the possible realization of more economical devices. Organic materials are abundant and easily handling. Unfortunately OPV cells efficiency is significantly lower than that of inorganic-based devices, representing a big point of weakness at the present. This is mainly due to the fact that organic semiconductors have a much higher band gap with respect to inorganic semiconductors. In addition, OPV cells are very susceptible to oxygen and water. In this paper we will describe some of the different approaches to the understanding and improving of organic photovoltaic devices

Ecophysiological response of Sorghum halepense populations to reduced rates of nicosulfuron

The control and regrowth after nicosulfuron reduced rate treatment of Johnsongrass (Sorghum halepense L. Pers.) populations, from seven Argentinean locations, were evaluated in pot experiments to assess if differential performance could limit the design and implementation of integrated weed management programs. Populations from humid regions registered a higher sensibility to reduced rates of nicosulfuron than populations from subhumid regions. This effect was visualised in the values of regression coefficient of the non-linear models (relating fresh weight to nicosulfuron rate), and in the time needed to obtain a 50% reduction of photosynthesis rate and stomatal conductance. The least leaf CO2 exchange of subhumid populations could result in a lower foliar absorption and translocation of nicosulfuron, thus producing less control and increasing their ability to sprout and produce new aerial biomass. The three populations from subhumid regions, with less sensibility to nicosulfuron rates, presented substantial difference in fresh weight, total rhizome length and number of rhizome nodes, when they were evaluated 20 week after treatment. In consequence, a substantial Johnsongrass re-infestation could occur, if rates below one-half of nicosulfuron labeled rate were used to control Johnsongrass in subhumid regions.Foram conduzidos experimentos sob condições controladas, a fim de se investigar os efeitos de doses reduzidas de nicosulfuron, no controle e rebrota de populações de capim massambará (Sorghum halepense), de sete localidades da Argentina, visando programas de manejo integrado. As populações das regiões úmidas registraram maior sensibilidade a doses reduzidas de nicosulfuron, em relação àquelas das regiões subúmidas.\nEsse efeito foi observado nos valores do coeficiente de regressão, das curvas de dose-resposta de modelo loglogístico, que relacionam a biomassa fresca com doses de nicosulfuron; tal efeito foi observado também no tempo necessário para se obter 50% da redução da fotossíntese e da condutância estomática. O menor intercâmbio de CO2, obtido nessas populações subúmidas, pode ter contribuído para a absorção e translocação mais baixa do nicosulfuron, tendo produzido menor controle e, conseqüentemente, tendo aumentado sua capacidade de rebrotar e produzir nova biomassa aérea ao final do ciclo. As três populações das regiões subúmidas, com menor sensibilidade ao nicosulfuron, apresentaram uma diferença substancial na biomassa fresca, no comprimento total e no número de nódulos dos rizomas, quando foram avaliadas vinte semanas após o tratamento com herbicida. Os resultados obtidos sugerem que se forem usadas doses de nicosulfuron menores do que as recomendadas, pode ocorrer uma severa rebrota do capim massambará em regiões subúmidas

Photocatalytic inactivation of Escherichia coli bacteria in water using low pressure plasma deposited TiO2 cellulose fabric

Fabrics obtained from cellulose spinning, extracted from Spanish broom, were coated with TiO2 film, through the low pressure plasma sputtering technique, in order to get antibacterial activity. The obtained fabrics were used for the photocatalytic degradation of Escherichia coli, by irradiation with UV-light emitting diodes (UV-LED), in a batch photocatalytic reactor. Before and after functionalization treatments, cellulosic substrates were chemically characterized by X-ray photoelectron spectroscopy (XPS) analyses. Water Contact Angle (WCA) measurements allowed obtaining information about the hydrophilicity of the materials, while their antibacterial efficiency was determined at several initial concentrations (from 103 up to 108 CFU mL−1) of bacteria in distilled water, bottled water and synthetic wastewater. It was found that photocatalytic reactions were capable of achieving up to 100% bacterial inactivation in 1 h of treatment, following a pseudo-first order kinetic model. No bacterial regrowth was observed after photocatalytic treatments in almost all experimental conditions. In contrast, during photolytic treatment (i.e. in the absence of the TiO2 coated fabrics) bacteria recovered their initial concentration after 3 h in the dark. Finally, the reusability of the plasma modified fibers to inactivate bacteria was studied

Resposta ecofisiológica de populações de Sorghum halepense a doses reduzidas de nicosulfuron

The control and regrowth after nicosulfuron reduced rate treatment of Johnsongrass (Sorghum halepense L. Pers.) populations, from seven Argentinean locations, were evaluated in pot experiments to assess if differential performance could limit the design and implementation of integrated weed management programs. Populations from humid regions registered a higher sensibility to reduced rates of nicosulfuron than populations from subhumid regions. This effect was visualised in the values of regression coefficient of the non-linear models (relating fresh weight to nicosulfuron rate), and in the time needed to obtain a 50% reduction of photosynthesis rate and stomatal conductance. The least leaf CO2 exchange of subhumid populations could result in a lower foliar absorption and translocation of nicosulfuron, thus producing less control and increasing their ability to sprout and produce new aerial biomass. The three populations from subhumid regions, with less sensibility to nicosulfuron rates, presented substantial difference in fresh weight, total rhizome length and number of rhizome nodes, when they were evaluated 20 week after treatment. In consequence, a substantial Johnsongrass re-infestation could occur, if rates below one-half of nicosulfuron labeled rate were used to control Johnsongrass in subhumid regions.Foram conduzidos experimentos sob condições controladas, a fim de se investigar os efeitos de doses reduzidas de nicosulfuron, no controle e rebrota de populações de capim massambará (Sorghum halepense), de sete localidades da Argentina, visando programas de manejo integrado. As populações das regiões úmidas registraram maior sensibilidade a doses reduzidas de nicosulfuron, em relação àquelas das regiões subúmidas. Esse efeito foi observado nos valores do coeficiente de regressão, das curvas de dose-resposta de modelo loglogístico, que relacionam a biomassa fresca com doses de nicosulfuron; tal efeito foi observado também no tempo necessário para se obter 50% da redução da fotossíntese e da condutância estomática. O menor intercâmbio de CO2, obtido nessas populações subúmidas, pode ter contribuído para a absorção e translocação mais baixa do nicosulfuron, tendo produzido menor controle e, conseqüentemente, tendo aumentado sua capacidade de rebrotar e produzir nova biomassa aérea ao final do ciclo. As três populações das regiões subúmidas, com menor sensibilidade ao nicosulfuron, apresentaram uma diferença substancial na biomassa fresca, no comprimento total e no número de nódulos dos rizomas, quando foram avaliadas vinte semanas após o tratamento com herbicida. Os resultados obtidos sugerem que se forem usadas doses de nicosulfuron menores do que as recomendadas, pode ocorrer uma severa rebrota do capim massambará em regiões subúmidas.Facultad de Ciencias Agrarias y Forestale

Resposta ecofisiológica de populações de Sorghum halepense a doses reduzidas de nicosulfuron

The control and regrowth after nicosulfuron reduced rate treatment of Johnsongrass (Sorghum halepense L. Pers.) populations, from seven Argentinean locations, were evaluated in pot experiments to assess if differential performance could limit the design and implementation of integrated weed management programs. Populations from humid regions registered a higher sensibility to reduced rates of nicosulfuron than populations from subhumid regions. This effect was visualised in the values of regression coefficient of the non-linear models (relating fresh weight to nicosulfuron rate), and in the time needed to obtain a 50% reduction of photosynthesis rate and stomatal conductance. The least leaf CO2 exchange of subhumid populations could result in a lower foliar absorption and translocation of nicosulfuron, thus producing less control and increasing their ability to sprout and produce new aerial biomass. The three populations from subhumid regions, with less sensibility to nicosulfuron rates, presented substantial difference in fresh weight, total rhizome length and number of rhizome nodes, when they were evaluated 20 week after treatment. In consequence, a substantial Johnsongrass re-infestation could occur, if rates below one-half of nicosulfuron labeled rate were used to control Johnsongrass in subhumid regions.Foram conduzidos experimentos sob condições controladas, a fim de se investigar os efeitos de doses reduzidas de nicosulfuron, no controle e rebrota de populações de capim massambará (Sorghum halepense), de sete localidades da Argentina, visando programas de manejo integrado. As populações das regiões úmidas registraram maior sensibilidade a doses reduzidas de nicosulfuron, em relação àquelas das regiões subúmidas. Esse efeito foi observado nos valores do coeficiente de regressão, das curvas de dose-resposta de modelo loglogístico, que relacionam a biomassa fresca com doses de nicosulfuron; tal efeito foi observado também no tempo necessário para se obter 50% da redução da fotossíntese e da condutância estomática. O menor intercâmbio de CO2, obtido nessas populações subúmidas, pode ter contribuído para a absorção e translocação mais baixa do nicosulfuron, tendo produzido menor controle e, conseqüentemente, tendo aumentado sua capacidade de rebrotar e produzir nova biomassa aérea ao final do ciclo. As três populações das regiões subúmidas, com menor sensibilidade ao nicosulfuron, apresentaram uma diferença substancial na biomassa fresca, no comprimento total e no número de nódulos dos rizomas, quando foram avaliadas vinte semanas após o tratamento com herbicida. Os resultados obtidos sugerem que se forem usadas doses de nicosulfuron menores do que as recomendadas, pode ocorrer uma severa rebrota do capim massambará em regiões subúmidas.Facultad de Ciencias Agrarias y Forestale

Disinfestazione di manufatti lignei da parassiti larvali mediante tecniche da vuoto

Wooden artifacts are subject to being heavily damaged by the attack of worms which develop in the wood through the eggs deposited by adult pests before their final transformation into flying insects. Among the most dangerous species are xylophagous (wood-boring) insects, whose larvae are responsible for one of the most efficient wood-destroying mechanisms in wooden cultural heritage. Their elimination has always been a huge problem for the conservation of wood. In this work, we present the experimentation of a simple vacuum technique to disinfest wood from the larval Hylotrupes bajolus. We will also introduce the possibility of treating large-sized wooden artifacts by means of a special vacuum chamber.I manufatti lignei sono soggetti ad essere fortemente danneggiati dall’attacco di parassiti che, nella loro forma adulta, prolificano nel legno depositando le loro uova. Tra le specie più pericolose ci sono gli insetti xilofagi, le cui larve sono responsabili di uno dei più efficaci meccanismi di degradazione dei manufatti artistici lignei. La loro eliminazione, da sempre, costituisce un problema enorme per lo stato di conservazione del legno. In questo lavoro, viene presentata la sperimentazione di una nuova semplice tecnica da vuoto per la disinfestazione del legno da parte del Hylotrupes bajulus nella sua forma larvale. Viene inoltre presentata la possibilità di trattare manufatti lignei di grandi dimensioni per mezzo di una speciale camera da vuoto

A vertical-mode decomposition to investigate low-frequency internal motion across the Atlantic at 26° N

Hydrographic data from full-depth moorings maintained by the Rapid/\-MOCHA project and spanning the Atlantic at 26° N are decomposed into vertical modes in order to give a dynamical framework for interpreting the observed fluctuations. Vertical modes at each mooring are fit to pressure perturbations using a Gauss-Markov inversion. Away from boundaries, the vertical structure is almost entirely described by the first baroclinic mode, as confirmed by high correlation between the original signal and reconstructions using only the first baroclinic mode. These first baroclinic motions are also highly coherent with altimetric sea surface height (SSH). Within a Rossby radius (45 km) of the western and eastern boundaries, however, the decomposition contains significant variance at higher modes, and there is a corresponding decrease in the agreement between SSH and either the original signal or the first baroclinic mode reconstruction. Compared to the full transport signal, transport fluctuations described by the first baroclinic mode represent <25 km of the variance within 10 km of the western boundary, in contrast to 60 km at other locations. This decrease occurs within a Rossby radius of the western boundary. At the eastern boundary, a linear combination of many baroclinic modes is required to explain the observed vertical density profile of the seasonal cycle, a result that is consistent with an oceanic response to wind-forcing being trapped to the eastern boundary