Fitoestabilización de metales pesados en sedimentos costeros asistida por bacterias rizosféricas

El problema de la contaminación ambiental por metales pesados se está convirtiendo cada vez más en un asunto de interés global debido al incremento de la industrialización y la alteración de los ciclos biogeoquímicos naturales. Estuarios y costas son particularmente ecosistemas particularmente amenazados. En el estuario de Odiel (SW España), tanto las corrientes naturales como las causas antropogénicas son responsables de altos contenidos de metales en los sedimentos. Sus altas concentraciones de sales son adecuadas para el crecimiento de plantas halófilas, como las especies del género Spartina, que poseen alta capacidad para la acumulación de metales, lo que las convierte en candidatas idóneas para procesos de fitoestabilización. El objetivo principal de este trabajo fue el aislamiento y caracterización de bacterias rizosféricas con el fin de proponer un inoculante autóctono adecuado con potencial para la fitorremediación de marismas contaminadas del Odiel. Las cepas Gram-negativas Pantoea agglomerans RSO6 y RSO7 junto con la cepa Gram-positiva Bacillus aryabhattai RSO25, fueron previamente seleccionadas de entre 25 bacterias autóctonas aisladas de la rizósfera de Spartina maritima. El criterio de selección se basó en características como: resistencia a metales pesados, bioacumulación, propiedades promotoras del crecimiento de plantas (PGP) y capacidad de formar biofilms. Para testar las propiedades promotoras del crecimiento vegetal, se utilizó como planta modelo Spartina densiflora, la cual, si bien es una planta invasora, está ampliamente naturalizada en las marismas del Tinto-Odiel y muestra una gran capacidad de acumular metales en la raíz y el rizosedimento. Las cepas RSO6 y RSO7 mejoraron la germinación de semillas de Spartina densiflora en un 250% en sedimentos contaminados, mientras que RSO25 aumentó en un 300%, con respecto a controles no inoculados. El consorcio bacteriano no consiguió una mayor mejora. Las tres cepas, particularmente las Gram-negativas, promovieron el crecimiento de las plantas y mitigaron el estrés metálico como se pudo apreciar en los parámetros fisiológicos tales como funcionalidad del aparato fotosintético (PSII) y el mantenimiento del equilibrio de nutrientes. En cuanto a la absorción de metales, mientras que las bacterias Gram-negativas no afectaron significativamente la acumulación de metal en los tejidos vegetales, la cepa Gram-positiva aumentó la acumulación de metal sólo en las raíces, sin carga adicional a los brotes. Nuestros resultados confirman la posibilidad de modular el crecimiento de las plantas y la acumulación de metales en sedimentos contaminados tras la inoculación con bacterias seleccionadas, así como la idoneidad de las interacciones halófilas-rizobacterias como una herramienta biotecnológica para propósitos de fitostabilización, evitando así el riesgo de translocación de metales hacia la parte aérea y su entrada a la cadena alimenticia.The problem of environmental pollution by heavy metals is increasingly becoming a matter of global concern due to increased industrialization and alteration of natural biogeochemical cycles. Estuaries and coasts are particularly threatened ecosystems. In the estuary of Odiel (SW Spain), both natural currents and anthropogenic causes are responsible for high metal contents in the sediments. The high concentration of salt in the estuary make it suitable for the growth of halophilic plants, such as species of the genus Spartina, which possess a high capacity for the accumulation of metals and it is considered as an appropriate candidate for phytostabilization processes. The main objective of this work was the isolation and characterization of bacteria from the rhizosphere of Spartina plants, in order to propose a suitable native inoculant with potential for the phytoremediation of contaminated marshes of Odiel. The Gram-negative strains Pantoea agglomerans RSO6 and RSO7 together with the Gram-positive strain Bacillus aryabhattai RSO25 were previously selected from 25 autochthonous bacteria isolated from the rhizosphere of Spartina maritima. The selection criterion was based on characteristics such as: heavy metal resistance, bioaccumulation, plant growth promoting properties (PGP) and ability to form biofilms. In order to test the plant growth promoter properties, Spartina densiflora was used as a model plant, which, although it is an invasive plant, is widely naturalized in the Tinto-Odiel marshes and shows a great capacity to accumulate metals in the root and the rhizosediment. RSO6 and RSO7 strains improved seed germination of Spartina densiflora by 250% in contaminated sediments, while RSO25 increased by 300%, compared to uninoculated controls. The bacterial consortium did not achieve further improvement. The three strains, particularly Gram-negative, promoted plant growth and mitigated metal stress as could be seen in physiological parameters such as functionality of the photosynthetic apparatus (PSII) and maintenance of nutrient balance. Regarding the uptake of metals, while Gram-negative bacteria did not significantly affect metal accumulation in plant tissues, the Gram-positive strain increased metal accumulation only in the roots, with no additional loading to the shoots. Our results confirm the possibility of modulating plant growth and accumulation of metals in contaminated sediments after inoculation with selected bacteria, as well as the suitability of halophilic-rhizobacterial interactions as a biotechnological tool for phytostabilization purposes, thus avoiding the risk of translocation of metals to the aerial part of the plants and their entry into the food chain

Radio over fiber: An alternative broadband network technology for Iot

Wireless broadband access networks have been positioning themselves as a good solution for manufacturers and users of IoT (internet of things) devices, due mainly to the high data transfer rate required over terminal devices without restriction of information format. In this work, a review of two Radio over Fiber strategies is presented. Both have excellent performance and even offer the possibility to extend wireless area coverage where mobile networks do not reach or the 802.11 network presents issues. Radio Frequency over Fiber (RFoF) and intermediate Frequency over Fiber (IFoF) are two transmission strategies compatible with the required new broadband services and both play a key role in the design of the next generation integrated optical–wireless networks, such as 5G and Satcom networks, including on RAU (Remote Antenna Unit) new functionalities to improve their physical dimensions, employing a microelectronic layout over nanometric technologies

CMOS linear laser driver for intermediate frequency over fiber (IFoF) links

The main objective of the proposed linear laser driver (LLD) is to reduce signal distortion in an analog direct modulation laser configuration used for intermediate frequency over fiber links. This work draws on an open-loop configuration featuring two differential pair blocks in a cascade arrangement to achieve a bandwidth measurement of 415 MHz at the half-power point, a total harmonic distortion of 4.57% for a fundamental frequency of 100 MHz, and an amplitude of 100 mVpp. The LLD provides a gain of 12.3 dB for a differential output and an output impedance of 46 Ω. The design, layout, and integration correspond to the process design kit for TSMC 65-nm CMOS technology. Experimental results show the advantage over other previously reported laser drivers

Laser driver design in 65-nm CMOS technology for IFoF optical links

Broadband mobile networks have experimented an accelerated growth in the passed five decades culminating this development with 5G networks. This evolution demands an efficient and not expensive solution for optical-wireless front-end. Thus, information delivered by mobile stations is repeated over a Distributed Antenna System (DAS), where Remote Antenna Unit (RAU) integer optical and wireless modules. A non-linear response from light source means a major problem for an analog signal in comparison with digital one. The main problem with non linearity is signal dispersion giving as result alteration of signal shape form. In this direction there are some options from IC electronic design to interact with optical source, first the use of a linear drive circuit that delivers a certain amount of electric current for a voltage input signal, the second option is the use of pre-distortion or post-distortion electronic blocks to guarantee a lineal response from optical source. This work supposes a first approach and design of a linear laser driver in 65-nm CMOS technology that includes layout design

Laser driver design in 65-nm CMOS technology for IFoF optical links

Broadband mobile networks have experimented an accelerated growth in the passed five decades culminating this development with 5G networks. This evolution demands an efficient and not expensive solution for optical-wireless front-end. Thus, information delivered by mobile stations is repeated over a Distributed Antenna System (DAS), where Remote Antenna Unit (RAU) integer optical and wireless modules. A non-linear response from light source means a major problem for an analog signal in comparison with digital one. The main problem with non linearity is signal dispersion giving as result alteration of signal shape form. In this direction there are some options from IC electronic design to interact with optical source, first the use of a linear drive circuit that delivers a certain amount of electric current for a voltage input signal, the second option is the use of pre-distortion or post-distortion electronic blocks to guarantee a lineal response from optical source. This work supposes a first approach and design of a linear laser driver in 65-nm CMOS technology that includes layout design

Generación de una tensión de polarización variable para la compensación de efectos de proceso en LNA sin inductores

This work presents and evaluates different alternatives to implement a bias circuit that compensates for variations in the manufacturing process in a low noise amplifier (LNA) based on a common gate stage with transconductance enhancement. The study covers three topologies and a comparison and verification is made through corner analysis and Monte Carlo.Este trabajo presenta y evalúa diferentes alternativas para implementar un circuito de polarización que compense las variaciones del proceso de fabricación en un amplificador de bajo ruido (LNA) basado en una etapa puerta común con realce de transconductancia. El estudio cubre tres topologías y se efectúa una comparativa y comprobación mediante análisis de corners y Monte Carlo

Radio over Fiber: An Alternative Broadband Network Technology for IoT

Wireless broadband access networks have been positioning themselves as a good solution for manufacturers and users of IoT (internet of things) devices, due mainly to the high data transfer rate required over terminal devices without restriction of information format. In this work, a review of two Radio over Fiber strategies is presented. Both have excellent performance and even offer the possibility to extend wireless area coverage where mobile networks do not reach, or the 802.11 network presents issues. Radio Frequency over Fiber (RFoF) and intermediate Frequency over Fiber (IFoF) are two transmission strategies compatible with the required new broadband services and both play a key role in the design of the next generation integrated optical–wireless networks, such as 5G and Satcom networks, including on RAU (Remote Antenna Unit) new functionalities to improve their physical dimensions, employing a microelectronic layout over nanometric technologies

Metodología de diseño de LNA de banda ancha robustos frente a variaciones de proceso

Los amplificadores de bajo ruido requieren cumplir unas especificaciones de diseño muy estrictas. Esto hace delicado y tedioso su diseño, especialmente si se desea garantizar su robustez al sufrir las variaciones de proceso. Para solventarlo, este trabajo presenta una metodología de optimización

Metodología de diseño de LNA de banda ancha robustos frente a variaciones de proceso

Los amplificadores de bajo ruido requieren cumplir unas especificaciones de diseño muy estrictas. Esto hace delicado y tedioso su diseño, especialmente si se desea garantizar su robustez al sufrir las variaciones de proceso. Para solventarlo, este trabajo presenta una metodología de optimización