Mechanisms for photon sorting based on slit-groove arrays

Mechanisms for one-dimensional photon sorting are theoretically studied in the framework of a couple mode method. The considered system is a nanopatterned structure composed of two different pixels drilled on the surface of a thin gold layer. Each pixel consists of a slit-groove array designed to squeeze a large fraction of the incident light into the central slit. The Double-Pixel is optimized to resolve two different frequencies in the near infrared. This system shows a high transmission efficiency and a small crosstalk. Its response is found to strongly depend on the effective area shared by overlapping pixels. Three different regimes for the process of photon sorting are identified and the main physical trends underneath in such regimes are unveiled. Optimal efficiencies for the photon sorting are obtained for a moderate number of grooves that overlap with grooves of the neighbor pixel. Results could be applied to optical and infrared detectors.Comment: 12 pages, 4 figure

Transmittance of a subwavelength aperture flanked by a finite groove array \\ placed near the focus of a conventional lens

One-dimensional light harvesting structures illuminated by a conventional lens are studied in this paper. Our theoretical study shows that high transmission efficiencies are obtained when the structure is placed near the focal plane of the lens. The considered structure is a finite slit-groove array (SGA) with a given number of grooves that are symmetrically distributed with respect to a central slit. The SGA is nano-patterned on an opaque metallic film. It is found that a total transmittance of 80% is achieved even for a single slit when (i) Fabry-Perot like modes are excited inside the slit and (ii) the effective cross section of the aperture becomes of the order of the full width at half maximum of the incident beam. A further enhancement of 8% is produced by the groove array. The optimal geometry for the groove array consists of a moderate number of grooves ($\geq 4$) at either side of the slit, separated by a distance of half the incident wavelength $\lambda$. Grooves should be deeper (with depth $\geq \lambda/4$) than those typically reported for plane wave illumination in order to increase their individual scattering cross section.Comment: 7 pages, 6 figure

Thioredoxin dependent changes in the redox states of FurA from Anabaena sp. PCC7120

FurA is a multifunctional regulator in cyanobacteria that contains five cysteines, four of them arranged into two CXXC motifs. Lack of a structural zinc ion enables FurA to develop disulfide reductase activity. In vivo, FurA displays several redox isoforms, and the oxidation state of its cysteines determines its activity as regulator and its ability to bind different metabolites. Because of the relationship between FurA and the control of genes involved in oxidative stress defense and photosynthetic metabolism, we sought to investigate the role of type m thioredoxin TrxA as a potential redox partner mediating dithiol-disulfide exchange reactions necessary to facilitate the interaction of FurA with its different ligands. Both in vitro cross-linking assays and in vivo two-hybrid studies confirmed the interaction between FurA and TrxA. Light to dark transitions resulted in reversible oxidation of a fraction of the regulator present in Anabaena sp. PCC7120. Reconstitution of an electron transport chain using E. coli NADPH-thioredoxin-reductase followed by alkylation of FurA reduced cysteines evidenced the ability of TrxA to reduce FurA. Furthermore, the use of site-directed mutants allowed us to propose a plausible mechanism for FurA reduction. These results point to TrxA as one of the redox partners that modulates FurA performance

Contributions on lindane degradation by Microcystis aeruginosa PCC 7806

Cyanobacteria are able to tolerate, and even metabolize, moderate doses of organochlorine pesticides, such as lindane (¿-hexachlorocyclohexane), one of the most persistent and widely used in recent decades. Previous work showed that Microcystis aeruginosa PCC 7806 degrades lindane and that, in the presence of the pesticide, microcystin synthesis is enhanced. In this work, using in silico approaches, we have identified in M. aeruginosa putative homologues of the lin genes, involved in lindane degradation in Sphingobium japonicum UT26S. Real-time RT-PCR assays showed that the putative linC gene was induced in the presence of 7 mg/L of lindane. Additionally, prxA, encoding a peroxiredoxin, and involved in oxidative stress response, was also induced when lindane was present. Taking into account these results, M. aeruginosa PCC 7806 may degrade lindane through a metabolic pathway involving a putative 2, 5-dichloro-2, 5-cyclohexadiene-1, 4-diol dehydrogenase encoded by a linC homologue. However, the low similarity of the other potential lin homologues suggest the existence of an alternative pathway different to that of heterotrophic microorganisms such as S. japonicum

Biobanco: Herramienta fundamental para la investigación biomédica actual

Biomedical research aimed at the preservation of health and disease management requires nowadays a bidirectional and articulated collaboration between basic and clinical work, which has generated a new trend called translational research. This type of research is based on the ability to provide timely, relevant, effective and personalized healthcare, for which biological samples, and associated clinical information are required, while ensuring safety, quality and confidentiality for donors. In order to promote translational research and the application of the advances in knowledge and technology from research and innovation, the support of accessible infrastructure is required to facilitate the rapid experimental demonstration of a hypothesis or testing a previously simulated model. Among the diverse biomedical and healthcare existing platforms, the Biobanks, in their various forms constitute one of the most attractive platforms contributing to establish bridges between the basic and clinical research with the clinical practice. The need for human biological samples of high quality, and at the same time, the obligation to preserve the rights of donors, has raised the Biobanks’ management to the scientific and technical category, with the added particular complexity of involving multiple aspects including scientific, ethical, legal, and social factors. This series of articles that will be published in different issues of the magazine in 2016, aims to make a critical review of the most relevant aspects regarding the management of Biobanks for research, and to propose a series of guidelines for the management of human biological material as developed by the program Cardiecol.La investigación biomédica enfocada a la preservación de la salud y manejo de la enfermedad requiere hoy del trabajo articulado bidireccional entre básicos y clínicos, lo cual ha generado una nueva tendencia, denominada investigación traslacional. Este tipo de investigación se fundamenta en poder brindar una atención en salud oportuna, pertinente, eficaz y personalizada, para lo cual se requieren muestras biológicas e información clínica asociada, garantizando a su vez seguridad, calidad y confidencialidad para los donantes. Promover la investigación traslacional y la aplicación de los avances del conocimiento y de la tecnología derivados de la investigación y la innovación, requiere del apoyo de infraestructuras de fácil acceso que faciliten la rápida demostración experimental de una hipótesis o la comprobación de un modelo simulado previamente. Dentro de las diversas plataformas biomédicas y de salud existentes, los Biobancos, en sus diferentes modalidades, se constituyen en una de las más atractivas plataformas a la hora de contribuir a establecer puentes entre la investigación básica y clínica, con la práctica asistencial. La necesidad de contar con muestras biológicas humanas de alta calidad y, al mismo tiempo, la obligación de preservar los derechos de los donantes, ha elevado la gestión de los Biobancos a la categoría de disciplina científico-técnica, con una complejidad particular que involucra múltiples aspectos entre los cuales se incluyen aspectos científicos, técnicos, éticos, jurídicos y sociales. Esta serie de artículos, que serán publicados en los diferentes números de la revista durante el 2016, tienen como objetivo hacer una revisión crítica de los aspectos más relevantes en torno a la gestión de los Biobancos con fines de investigación y proponer una serie de guías de manejo del material biológico humano a conservar las cuales se han desarrollado en el marco del Programa Cardiecol

Biobanco: Herramienta fundamental para la investigación biomédica actual

Biomedical research aimed at the preservation of health and disease management requires nowadays a bidirectional and articulated collaboration between basic and clinical work, which has generated a new trend called translational research. This type of research is based on the ability to provide timely, relevant, effective and personalized healthcare, for which biological samples, and associated clinical information are required, while ensuring safety, quality and confidentiality for donors. In order to promote translational research and the application of the advances in knowledge and technology from research and innovation, the support of accessible infrastructure is required to facilitate the rapid experimental demonstration of a hypothesis or testing a previously simulated model. Among the diverse biomedical and healthcare existing platforms, the Biobanks, in their various forms constitute one of the most attractive platforms contributing to establish bridges between the basic and clinical research with the clinical practice. The need for human biological samples of high quality, and at the same time, the obligation to preserve the rights of donors, has raised the Biobanks’ management to the scientific and technical category, with the added particular complexity of involving multiple aspects including scientific, ethical, legal, and social factors. This series of articles that will be published in different issues of the magazine in 2016, aims to make a critical review of the most relevant aspects regarding the management of Biobanks for research, and to propose a series of guidelines for the management of human biological material as developed by the program Cardiecol.La investigación biomédica enfocada a la preservación de la salud y manejo de la enfermedad requiere hoy del trabajo articulado bidireccional entre básicos y clínicos, lo cual ha generado una nueva tendencia, denominada investigación traslacional. Este tipo de investigación se fundamenta en poder brindar una atención en salud oportuna, pertinente, eficaz y personalizada, para lo cual se requieren muestras biológicas e información clínica asociada, garantizando a su vez seguridad, calidad y confidencialidad para los donantes. Promover la investigación traslacional y la aplicación de los avances del conocimiento y de la tecnología derivados de la investigación y la innovación, requiere del apoyo de infraestructuras de fácil acceso que faciliten la rápida demostración experimental de una hipótesis o la comprobación de un modelo simulado previamente. Dentro de las diversas plataformas biomédicas y de salud existentes, los Biobancos, en sus diferentes modalidades, se constituyen en una de las más atractivas plataformas a la hora de contribuir a establecer puentes entre la investigación básica y clínica, con la práctica asistencial. La necesidad de contar con muestras biológicas humanas de alta calidad y, al mismo tiempo, la obligación de preservar los derechos de los donantes, ha elevado la gestión de los Biobancos a la categoría de disciplina científico-técnica, con una complejidad particular que involucra múltiples aspectos entre los cuales se incluyen aspectos científicos, técnicos, éticos, jurídicos y sociales. Esta serie de artículos, que serán publicados en los diferentes números de la revista durante el 2016, tienen como objetivo hacer una revisión crítica de los aspectos más relevantes en torno a la gestión de los Biobancos con fines de investigación y proponer una serie de guías de manejo del material biológico humano a conservar las cuales se han desarrollado en el marco del Programa Cardiecol

Optimal light harvesting structures at optical and infrared frequencies

One-dimensional light harvesting structures with a realistic geometry nano-patterned on an opaque metallic film are optimized to render high transmission efficiencies at optical and infrared frequencies. Simple design rules are developed for the particular case of a slit-groove array with a given number of grooves that are symmetrically distributed with respect to a central slit. These rules take advantage of the hybridization of Fabry-Perot modes in the slit and surface modes of the corrugated metal surface. Same design rules apply for optical and infrared frequencies. The parameter space of the groove array is also examined with a conjugate gradient optimization algorithm that used as a seed the geometries optimized following physical intuition. Both uniform and nonuniform groove arrays are considered. The largest transmission enhancement, with respect to a uniform array, is obtained for a chirped groove profile. Such enhancement is a function of the wavelength. It decreases from 39% in the optical part of the spectrum to 15% at the long wavelength infrared.Comment: 13 pages, 5 figure

Responses of Anabaena sp. PCC7120 to lindane: Physiological effects and differential expression of potential lin genes

Abstract Lindane (γ‐HCH) is an organochlorine pesticide that causes huge environmental concerns worldwide due to its recalcitrance and toxicity. The use of the cyanobacterium Anabaena sp. PCC 7120 in aquatic lindane bioremediation has been suggested but information relative to this process is scarce. In the present work, data relative to the growth, pigment composition, photosynthetic/respiration rate, and oxidative stress response of Anabaena sp. PCC 7120 in the presence of lindane at its solubility limit in water are shown. In addition, lindane degradation experiments revealed almost a total disappearance of lindane in the supernatants of Anabaena sp. PCC 7120 culture after 6 days of incubation. The diminishing in lindane concentration was in concordance with an increase in the levels of trichlorobenzene inside the cells. Furthermore, to identify potential orthologs of the linA, linB, linC, linD, linE, and linR genes from Sphingomonas paucimobilis B90A in Anabaena sp. PCC 7120, a whole genome screening was performed allowing the identification of five putative lin orthologs (all1353 and all0193 putative orthologs of linB, all3836 putative orthologs of linC, and all0352 and alr0353 putative orthologs of linE and linR, respectively) which could be involved in the lindane degradation pathway. Differential expression analysis of these genes in the presence of lindane revealed strong upregulation of one of the potential lin genes of Anabaena sp. PCC 7120