Monitoring degradation mechanisms in PTB7:PC71BM photovoltaic cells by means of impedance spectroscopy

© 2016. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/We have used impedance spectroscopy technique to monitor degradation mechanisms in organic solar cells based on a blend of PTB7:PC71BM. We have measured the impedance of the cell on a periodical basis for almost four months, and experimental data have been modeled using three different circuits. The evolution of the circuital parameters gives information about the device dynamical mechanisms. We have observed at high voltages a low frequency feature that is more pronounced along days of measurement. This low frequency arc has been associated to charge accumulation that is related to a worsening of charge extraction through the contacts. The simultaneous increase of recombination and low frequency resistances at high voltages (around V-oc) results in a decrease of the fill factor and therefore of the efficiency.Peer ReviewedPostprint (author's final draft

Towards more circular office fit-outs: a socio-technical descriptive framework of office fit-out processes

Ethyl (S)-3-hydroxybutyrate ((S)-E3HB) is naturally found as part of kiwi fruit aroma and is an important precursor for the production of several pharmaceuticals. (S)-E3HB can be produced in a whole cell biotransformation process from Ethylacetoacetate (EAA) using the yeast Saccharomyces cerevisiae. One way of improving the sustainability of such processes may be their integration into novel biorefinery concepts, which requires research to characterize the process and the byproduct formation. In this study it could be shown that (S)-E3HB biocatalysis with S. cerevisiae can be performed under anaerobic conditions with production rates between 4.0 × 10-3 and 2.5 × 10-2 g(S)-E3HB gbiomass -1 h-1 which are similar to the rates in conventional aerobic processes. The byproduct spectrum allows for the integration of the new anaerobic biotransformation process into a recently invented biorefinery concept in which the side product CO2 is further utilized to produce methane

Buenas prácticas ganaderas en hatos lecheros de Santa Rosa de Cabal, Risaralda, Colombia

The objective of the present study was to analyze the degree of compliance of these practices, by evaluation of 99 variables in 21 productive systems in Santa Rosa de Cabal, Risaralda. Only one of the farms complied with the 48 fundamental criteria required and, the degree of compliance of major and minor criteria was insufficient. Only 8 of the farms are certified as free of brucellosis and tuberculosis. The best performing areas are animal welfare (81%) and those related to the milking routine (79.1%); On the other hand, the most deficient were the control of veterinary drugs and agricultural products (5.8%), as well as the conditions of the cooling tank (32.6%). Through a Multiple Correspondence Analysis, a significant association was found between variables involved with the guarantee in the safety of the milk, regarding the operation, cleaning and disinfection of equipment that guarantee an adequate temperature. There was also an association between variables involved in the milking procedure and hygienic conditions during the milking procedure, involving both the operator and the animal. A lack of training and awareness about the importance of compliance with many of these criteria was found, this is a fundamental tool to obtain a diagnosis of the current sanitary status, and in which it may be necessary to take into account other variables, not included in the current checklist, for a later implementation and follow-up to improvement plans of the productive systems.El objetivo del presente trabajo fue analizar el grado de cumplimiento de BPG, mediante la evaluación de 99 variables en 21 sistemas productivos del municipio de Santa Rosa de Cabal, Risaralda. Solo uno de los predios cumplió con los 48 criterios fundamentales exigidos y en general, el grado de cumplimiento de criterios mayores y menores fue insuficiente. Solo 8 de los hatos están certificados como libres de brucelosis y tuberculosis. Las áreas de mejor desempeño son el bienestar animal (81%) y las relacionadas con la rutina de ordeño (79,1%); en cambio, las mas deficientes fueron el control de medicamentos veterinarios e insumos agropecuarios (5,8%), así como las condiciones del tanque de enfriamiento (32,6%). Mediante un Análisis de Correspondencia múltiple, se encontró asociación significativa entre variables que tienen que ver con la garantía en la inocuidad de la leche, en lo referente a la operación, limpieza y desinfección de equipos que garanticen una temperatura adecuada. También hubo asociación entre variables que tienen que ver con el procedimiento de ordeño y condiciones de higiene durante la faena, que involucran tanto al operario, como al animal. Se evidencia falta de capacitación y concientización acerca de la importancia del cumplimiento de muchos criterios de BPG, que es una herramienta fundamental para obtener un diagnostico del estado actual del hato, y en la cual posiblemente sea necesario tener en cuenta otras variables, no incluidas en la lista de verificación actual, para una posterior implementación y seguimiento a planes de mejoramiento de los sistemas productivos

Mejoramiento del porcentaje de proteina en maiz para ensilaje con el aumento y parcializaci 3n de la fertilizacion nitrogenada

In clay soils with poor drainage two trials were carried out with the objective of determining the effect of nitrogen application on maize (Zea mays L.) for silage on forage yield and protein content. In Trial 1, the treatments were two corn silage hybrids of different growing periods, SX-43 and INIA-150, sown at 90.000 plants ha-1 and four N rates: 0, 100, 200 and 400 kg N ha-1. In Trial 2, the treatments were two N rates: 200 and 400 kg of N ha-1, and three forms of N application: a) 1/2 at sowing + 1/2 at 30 cm plant height; b) 1/3 at sowing + 1/3 at 30 cm plant height + 1/3 at 60 cm plant height; and c) 1/4 at sowing + 1/4 at 30 cm plant height + 1/4 at 60 cm plant height +1/4 at flowering. One treatment was without N. In Trial 1 N application increased DM yield (P < 0.05), but no significant response was observed with N rates between 100 and 400 kg N ha-1, due to soil limitations. Forage production and protein percentage increased significantly with N application. In Trial 2, DM production in corn silage increased with higher N rates (P < 0.05). Forage protein percentage was increased by higher N rates and partitioning of the application. On increasing the partitioning of N from two to four applications, protein percentage of forage was increased by 23 and 37% for 200 and 400 kg of N ha-1, respectively.En suelos arcillosos de mal drenaje se realizaron dos ensayos con el objetivo de determinar la respuesta de ma\uedz (Zea mays L.) para ensilaje a la aplicaci\uf3n de N en el rendimiento y contenido de prote\uedna del forraje. En el Ensayo 1 los tratamientos correspondieron a dos h\uedbridos de ma\uedz para ensilaje de distinta precocidad, SX-43 e INIA-150, sembrados con una poblaci\uf3n de 90.000 plantas ha-1 y cuatro dosis de N: 0, 100, 200 y 400 kg N ha-1. En el Ensayo 2, los tratamientos fueron dos dosis de N: 200 y 400 kg N ha-1, y tres formas de aplicaci\uf3n de nitr\uf3geno: a) 1/2 a la siembra + 1/2 a 30 cm de altura de las plantas; b) 1/3 a la siembra + 1/3 a 30 cm de altura de las plantas + 1/3 a 60 cm de altura de plantas; y c) 1/4 a la siembra + 1/4 a 30 cm de altura de las plantas + 1/4 a 60 cm de altura de plantas +1/4 en floraci\uf3n. Adem\ue1s se incluy\uf3 un tratamiento sin aplicaci\uf3n de N. En el Ensayo 1, la aplicaci\uf3n de N aument\uf3 el rendimiento de MS (P < 0,05), sin embargo no hubo respuesta significativa entre 100 y 400 kg de N, debido a limitantes de suelo. La producci\uf3n y el porcentaje de prote\uedna del forraje aument\uf3 significativamente con la aplicaci\uf3n de N. En el Ensayo 2, la producci\uf3n de MS en el ma\uedz aument\uf3 con la aplicaci\uf3n de N (P < 0,05). El porcentaje de prote\uedna del forraje se increment\uf3 con mayores dosis de N y su parcializaci\uf3n. Al aumentar la parcializaci\uf3n del N de 2 a 4 aplicaciones se increment\uf3 el tenor proteico del forraje en 23 y 37 % para las dosis de 200 y 400 kg N ha-1, respectivamente

Small Unmanned Aerial Vehicles (Micro-UAVs, Drones) in Plant Ecology

Premise of the study: Low-elevation surveys with small aerial drones (micro–unmanned aerial vehicles [UAVs]) may be used for a wide variety of applications in plant ecology, including mapping vegetation over small- to medium-sized regions. We provide an overview of methods and procedures for conducting surveys and illustrate some of these applications. Methods: Aerial images were obtained by flying a small drone along transects over the area of interest. Images were used to create a composite image (orthomosaic) and a digital surface model (DSM). Vegetation classification was conducted manually and using an automated routine. Coverage of an individual species was estimated from aerial images. Results: We created a vegetation map for the entire region from the orthomosaic and DSM, and mapped the density of one species. Comparison of our manual and automated habitat classification confirmed that our mapping methods were accurate. A species with high contrast to the background matrix allowed adequate estimate of its coverage. Discussion: The example surveys demonstrate that small aerial drones are capable of gathering large amounts of information on the distribution of vegetation and individual species with minimal impact to sensitive habitats. Low-elevation aerial surveys have potential for a wide range of applications in plant ecology

Mutations in LAMB2 causing a severe form of synaptic congenital myasthenic syndrome

BackgroundWe describe a severe form of congenital myasthenic syndrome (CMS) associated with congenital nephrosis and ocular malformations caused by two truncating mutations in the gene encoding the laminin beta2 subunit (LAMB2).Methods and resultsMutational analysis in the affected patient, who has a history of a serious untoward reaction to treatment with acetylcholinesterase inhibition, revealed two frame-shifting heteroallelic mutations, a maternally inherited 1478delG and a paternally inherited 4804delC. An anconeus muscle biopsy demonstrated a profound distortion of the architecture and function of the neuromuscular junction, which was strikingly similar to that seen in mice lacking laminin beta2 subunit. The findings included: pronounced reduction of the axon terminal size with encasement of the nerve endings by Schwann cells, severe widening of the primary synaptic cleft and invasion of the synaptic space by the processes of Schwann cells, and moderate simplification of postsynaptic folds and intact expression of the endplate acetylcholinesterase. The endplate potential quantal content was notably reduced, while the frequencies and amplitudes of miniature endplate potentials were only moderately diminished and the decay phases of miniature endplate potentials were normal. Western blot analysis of muscle and kidney tissue and immunohistochemistry of kidney tissue showed no laminin beta2 expression.ConclusionThis case, which represents a new type of synaptic CMS, exemplifies the wide variability of phenotypes associated with LAMB2 mutations and underscores the fundamental role that laminin beta2 plays in the development of the human neuromuscular junction

Mapping grain boundary heterogeneity at the nanoscale in a positive temperature coefficient of resistivity ceramic

Despite being of wide commercial use in devices, the orders of magnitude increase in resistance that can be seen in some semiconducting BaTiO3-based ceramics, on heating through the Curie temperature (TC), is far from well understood. Current understanding of the behavior hinges on the role of grain boundary resistance that can be modified by polarization discontinuities which develop in the ferroelectric state. However, direct nanoscale resistance mapping to verify this model has rarely been attempted, and the potential approach to engineer polarization states at the grain boundaries, that could lead to optimized positive temperature coefficient (PTC) behavior, is strongly underdeveloped. Here we present direct visualization and nanoscale mapping in a commercially optimized BaTiO3-PbTiO3-CaTiO3 PTC ceramic using Kelvin probe force microscopy, which shows that, even in the low resistance ferroelectric state, the potential drop at grain boundaries is significantly greater than in grain interiors. Aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy reveal new evidence of Pb-rich grain boundaries symptomatic of a higher net polarization normal to the grain boundaries compared to the purer grain interiors. These results validate the critical link between optimized PTC performance and higher local polarization at grain boundaries in this specific ceramic system and suggest a novel route towards engineering devices where an interface layer of higher spontaneous polarization could lead to enhanced PTC functionality