Extended description of tunnel junctions for distributed modeling of concentrator multi-junction solar cells

One of the key components of highly efficient multi-junction concentrator solar cells is the tunnel junction interconnection. In this paper, an improved 3D distributed model is presented that considers real operation regimes in a tunnel junction. This advanced model is able to accurately simulate the operation of the solar cell at high concentraions at which the photogenerated current surpasses the peak current of the tunnel junctionl Simulations of dual-junction solar cells were carried out with the improved model to illustrate its capabilities and the results have been correlated with experimental data reported in the literature. These simulations show that under certain circumstances, the solar cells short circuit current may be slightly higher than the tunnel junction peak current without showing the characteristic dip in the J-V curve. This behavior is caused by the lateral current spreading toward dark regions, which occurs through the anode/p-barrier of the tunnel junction

Realistic performance prediction in nanostructured solar cells as a function of nanostructure dimensionality and density

The behavior of quantum dot, quantum wire, and quantum well InAs/GaAs solar cells is studied with a very simplified model based on experimental results in order to assess their performance as a function of the low bandgap material volume fraction fLOW. The efficiency of structured devices is found to exceed the efficiency of a non-structured GaAs cell, in particular under concentration, when fLOW is high; this condition is easier to achieve with quantum wells. If three different quasi Fermi levels appear with quantum dots the efficiency can be much higher

Molecular basis of the selective binding of MDMA enantiomers to the Alpha4Beta2 nicotinic receptor subtype: synthesis, pharmacological evaluation and mechanistic studies

The α4β2 nicotinic acetylcholine receptor (nAChR) is a molecular target of 3,4-methylenedioxymethamphetamine (MDMA), a synthetic drug also known as ecstasy, and it modulates the MDMA-mediated reinforcing properties. However, the enantioselective preference of the α4β2 nAChR subtype still remains unknown. Since the two enantiomers exhibit different pharmacological profiles and stereoselective metabolism, the aim of this study is to assess a possible difference in the interaction of the MDMA enantiomers with this nAChR subtype. To this end, we report a novel simple, yet highly efficient enantioselective synthesis of the MDMA enantiomers, in which the key step is the diastereoselective reduction of imides derived from optically pure tert-butylsulfinamide. The enantioselective binding to the receptor is examined using [3H]epibatidine in a radioligand assay. Even though the two enantiomers induced a concentration-dependent binding displacement, (S)-MDMA has an inhibition constant 13-fold higher than (R)-MDMA, which shows a Hill's coefficient not significantly different from unity, implying a competitive interaction. Furthermore, when NGF-differentiated PC12 cells were pretreated with the compounds, a significant increase in binding of [3H]epibatidine was found for (R)-MDMA, indicating up-regulation of heteromeric nAChR in the cell surface. Finally, docking and molecular dynamics studies have been used to identify the binding mode of the two enantiomers, which provides a structural basis to justify the differences in affinity from the differential interactions played by the substituents at the stereogenic center of MDMA. The results provide a basis to explore the distinct psychostimulant profiles of the MDMA enantiomers mediated by the α4β2 nAChR subtype

Demonstration of the operation principles of intermediate band solar cells at room temperature

In this work we report, for the first time at room temperature, experimental results that prove, simultaneously in the same device, the two main physical principles involved in the operation of intermediate band solar cells: (1) the production of sub-bandgap photocurrent by two optical transitions through the intermediate band; (2) the generation of an output voltage which is not limited by the photon energy absorption threshold. These principles, which had always required cryogenic temperatures to be evidenced all together, are now demonstrated at room temperature on an intermediate band solar cell based on InAs quantum dots with Al0.3Ga0.7As barriers

Development and RF-Performance of AlGaN/GaN and InAlN/GaN HEMTs on Large-Diameter High-Resistivity Silicon Substrates

A CMOS-compatible industrial processing and RF analysis of 150 mm GaN-on-HR-Si substrates with AlGaN and InAlN barrier is presented. Process development along with transfer to large-wafer scale is shown and some HEMT calibration devices produced on AlGaN/GaN following the aforementioned procedure are characterized in terms of RF-performance by using a set of measured multi-bias S-parameters. An automatic small-signal equivalent circuit extraction strategy for these AlGaN/GaN DUTs is validated and some de-embedded figures of merit are drawn out in order to initially evaluate this promising technology.This work is supported by the I Plan Propio de la Univ. de Málaga (PhD Grant-401), and the European Microwave Association™ by the EuMA Internship Award 2021 edition. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Mujeres en pie de paz: exclusión y memoria de las mujeres víctimas del conflicto armado desde sus territorios

La Constitución de 1991 abrió una oportunidad para que Colombia, luego de diferentes procesos de paz maltrechos, construyera las bases de un contrato social que evitara la exclusión y la desigualdad social, económica y política de una buena parte de la población, sobre todo la campesina. La exclusión y la desigualdad son algunas de las principales causas y orígenes del conflicto colombiano (Alape, 2004; Centro Nacional de Memoria Histórica, 2013), por más de que no exista una única versión sobre cuándo y por qué inició la guerra en Colombia (Comisión Histórica del Conflicto y sus Víctimas [CHCV], 2015). A pesar de que algunos grupos guerrilleros se incorporaron a la vida política institucional y fueron garantes del nuevo pacto social, la nueva Constitución fue una oportunidad perdida. Las desigualdades y la exclusión no cesaron para muchos colombianos y colombianas y el conflicto armado se recrudeció en la última década del siglo XX

Biodegradación de cianuro por Pseudomonas pseudoalcaligenes CECT5344. Análisis proteómico

El cianuro es un compuesto muy tóxico para los seres vivos ya que forma complejos muy estables con metales de transición, esenciales para la función de numerosas proteínas. A pesar de su toxicidad, se han descrito microorganismos que metabolizan cianuro debido a la posesión de estas características: una ruta para su degradación, un sistema de suministro de hierro (sideróforos) y una cadena de transporte de electrones insensible a cianuro. A partir de lodos procedentes del río Guadalquivir se ha aislado una bacteria que degrada cianuro en condiciones alcalinas, se ha identificado como Pseudomonas pseudoalcaligenes y se ha depositado en la colección española de cultivos tipo como CECT5344. El estudio del proteoma de P. pseudoalcaligenes ha permitido la identificación de proteínas relacionadas con resistencia a cianuro, biosíntesis de sideróforos y respuesta a estrés general. Otros estudios permitirán evaluar el uso potencial de la estirpe CECT5344 en la descontaminación de residuos y de zonas contaminadas con cianur

In vitro effect photodynamic therapy with differents photosensitizers on cariogenic microorganisms

Background: Antimicrobial photodynamic therapy has been proposed as an alternative to suppress subgingival species. This results from the balance among Streptococcus sanguis, Streptococcus mutans and Candida albicans in the dental biofilm. Not all the photosensitizers have the same photodynamic effect against the different microorganims. The objective of this study is to compare in vitro the photodynamic effect of methylene blue (MB), rose Bengal (RB) and curcumin (CUR) in combination with white light on the cariogenic microorganism S. mutans, S. sanguis and C. albicans. Results: Photodynamic therapy with MB, RB and CUR inhibited 6 log 10 the growth of both bacteria but at different concentrations: 0.31-0.62 µg/ml and 0.62-1.25 µg/ml RB were needed to photoinactivate S. mutans and S. sanguis, respectively//1.25-2.5 µg/ml MB for both species//whereas higher CUR concentrations (80-160 µg/ml and 160-320 µg/ml) were required to obtain the same reduction in S. mutans and S. sanguis viability respectively. The minimal fungicidal concentration of MB for 5 log10 CFU reduction (4.5 McFarland) was 80-160 µg/ml, whereas for RB it ranged between 320 and 640 µg/ml. For CUR, even the maximum studied concentration (1280 µg/ml) did not reach that inhibition. Incubation time had no effect in all experiments. Conclusions: Photodynamic therapy with RB, MB and CUR and white light is effective in killing S. mutans and S. sanguis strains, although MB and RB are more efficient than CUR. C. albicans required higher concentrations of all photosensitizers to obtain a fungicidal effect, being MB the most efficient and CUR ineffective