Optimización de un medio de cultivo para la germinación in vitro de semillas de Drosera capensis

En el presente trabajo se desarrolló un protocolo la germinación in vitro de Drosera Capensis género monotípico de planta carnívora en la familia Droseraceae, del cual tambien proviene la Dionaea Muscipula. Drosera capensis var. alba (Droseraceae) comúnmente conocido como rocío del sol (Fig. 1 ) es una planta nativa carnívora a Ciudad del Cabo en Sudáfrica. Drosera capensis L. (Droseraceae) es una pequeña especie formadora de rosetas nativa de la región del Cabo de Sudáfrica, y ha sido colocada fillogenéticamente dentro del subgénero Drosera sección Drosera (Rivadavia et al., 2003). Una población de D. capensis fue reportada recientemente como naturalizada a un pequeño arroyo dentro del Parque Nacional Real, bioregión de la costa central, Nueva Gales del Sur (Jobson 1954). Esta especie es comúnmente cultivada por entusiastas de plantas carnívoras y está disponible para su compra en muchos viveros de plantas . En Nueva Zelanda, esta especie ®gura como especie invasora (Heenan et al., 2004, NPPA 2008). También se registra como una mala hierba naturalizada en California (Estados Unidos de América) (GCW 2007, USDA 2012). Debido a su popularidad la demanda de estas plantas va en aumento sin embargo tienen fama de ser difíciles de cultivar. Por lo que el cultivo de tejidos vegetales por medio de la técnica de micropropagación podría se perfila a ser la manera por la cual podría obtenerse un mayor número de ejemplares en menor tiempo y sin necesidad de tener semillas. En el presente trabajo el objetivo principal es optimizar un medio de cultivo para la germinación de esta especie obteniendo resultados muy favorables. Se utilizaron semillas de plantas provenientes de los invernaderos de Ecovoraz. Posteriormente para el medio de cultivo se tomó como base el medio Murashige and Sook el cual se modificaron la concentración de micronutrientes y macronutrientes por lo que se realizaron soluciones Stock, y se utilizaron a una concentración al 50%,100%,125 y 150% . El medio de cultivo fue complementado con Ácido Giberèlico 3 0.25gr/L, 0.50gr/L, 0.75gr/L y 1gr/L. Obteniendo como resultado en el que la concentración de sales al 50% se obtuvo un promedio de 63 semillas germinadas, la concentración del 100% se obtuvo un promedio de 93semillas germinadas, mientras que en la concentración de nutrientes del 125% se obtuvo un promedio de 76 semillas germinadas, y en la concentración de 150% se obtuvo un promedio de 80 semillas terminadas. Por lo cual protocolo para establecer un mayor número de brotes es la concentración del 100 % de sales MS adicionando 1.5mg de Acido Giberelico

Finite control set model predictive control for a three-phase shunt active power filter with a kalman filter-based estimation

In this paper, the finite control set model predictive control is combined with the vector operation technique to be applied in the control of a three-phase active power filter. Typically, in the finite control set technique applied to three-phase power converters, eight different vectors are considered in order to obtain the optimum control signal by minimizing a cost function. On the other hand, the vector operation technique is based on dividing the grid voltage period into six different regions. The main advantage of combining both techniques is that for each region the number of possible voltage vectors to be considered can be reduced to a half, thus reducing the computational load employed by the control algorithm. Besides, in each region, only two phase-legs are switching at high frequency while the remaining phase-leg is maintained to a constant dc-voltage value during this interval. Accordingly, a reduction of the switching losses is obtained. Unlike the typical model predictive control methods which make use of the discrete differential equations of the converter, this method considers a Kalman filter in order to improve the behavior of the closed-loop system in noisy environments. Selected experimental results are exposed in order the demonstrate the validity of the control proposalPostprint (published version

A flexible experimental laboratory for distributed generation networks based on power inverters

In the recently deregulated electricity market, distributed generation based on renewable sources is becoming more and more relevant. In this area, two main distributed scenarios are focusing the attention of recent research: grid-connected mode, where the generation sources are connected to a grid mainly supplied by big power plants, and islanded mode, where the distributed sources, energy storage devices, and loads compose an autonomous entity that in its general form can be named a microgrid. To conduct a successful research in these two scenarios, it is essential to have a flexible experimental setup. This work deals with the description of a real laboratory setup composed of four nodes that can emulate both scenarios of a distributed generation network. A comprehensive description of the hardware and software setup will be done, focusing especially in the dual-core DSP used for control purposes, which is next to the industry standards and able to emulate real complexities. A complete experimental section will show the main features of the system.Peer ReviewedPostprint (published version

Receding-horizon model predictive control for a three-phase VSI with an LCL filter

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a Continuous Control Set Model Predictive Control with receding horizon for a threephase voltage source inverter with LCL filter, using a reduced model of the converter. The main advantages of using this reduced model is that an active damping can be achieved while the computational burden is reduced. Besides, in order to eliminate the model uncertainties, and also to achieve a zero steady state error, the proposed converter model includes an embedded integrator. Regarding the control scheme, a Kalman filter is used in order to estimate the three-phase currents without oscillation. The objective is to find the control signals vector that minimizes the error between the current and its reference. It is important to remark that the control signals obtained fromthe cost function can be used directly in a space vector modulator, without the use of additional controllers such as proportionalintegral or proportional-resonant. Compared with the Finite Control Set Model Predictive Control, the proposedmethod operates at fixed switching frequency without using any restriction in the cost function. Simulation and experimental results show that this proposalworks correctly even in case of grid harmonics and voltage sags.Peer ReviewedPostprint (author's final draft

Positive and Negative Sequence Control Strategies to Maximize the Voltage Support in Resistive-Inductive Grids During Grid Faults

Grid faults are one of the most severe perturbations in power systems. During these extreme disturbances, the reliability of the grid is compromised and the risk of a power outage is increased. To prevent this issue, distributed generation inverters can help the grid by supporting the grid voltages. Voltage support mainly depends on two constraints: the amount of injected current and the grid impedance. This paper proposes a voltage support control scheme that joins these two features. Hence, the control strategy injects the maximum rated current of the inverter. Thus, the inverter takes advantage of the distributed capacities and operates safely during voltage sags. Also, the controller selects the appropriate power references depending on the resistive-inductive grid impedance. Therefore the grid can be better supported since the voltage at the point of common coupling is improved. Several voltage objectives, which cannot be achieved together, are developed and discussed in detail. These objectives are threefold: a) to maximize the positive sequence voltage, b) to minimize the negative sequence voltage, and c) to maximize the difference between positive and negative sequence voltages. A mathematical optimal solution is obtained for each objective function. Experimental results are presented to validate the theoretical solutions.Postprint (author's final draft

Voltage support experimental analysis of a low-voltage ride-through strategy applied to grid-connected distributed inverters

In recent decades, different control strategies have been designed for the increasing integration of distributed generation systems. These systems, most of them based on renewable energies, use electronic converters to exchange power with the grid. Capabilities such as low-voltage ride-through and reactive current injection have been experimentally explored and reported in many research papers with a single inverter; however, these capabilities have not been examined in depth in a scenario with multiple inverters connected to the grid. Only few simulation works that include certain methods of reactive power control to solve overvoltage issues in low voltage grids can be found in the literature. Therefore, the overall objective of the work presented in this paper is to provide an experimental analysis of a low-voltage ride-through strategy applied to distributed power generation systems to help support the grid during voltage sags. The amount of reactive power will depend on the capability of each inverter and the amount of generated active power. The obtained experimental results demonstrate that, depending on the configuration of distributed generation, diverse inverters could have different control strategies. In the same way, the discussion of these results shows that the present object of study is of great interest for future research.Peer ReviewedPostprint (published version

Inmunoexpresión de enzimas antioxidantes en embriones de rata en cultivo en presencia de una elevada concentración de glucosa y poliaminas

La diabetes mellitus complicada con gestación produce malformaciones, retraso del desarrollo y pérdida de gestación. La glucosa es el teratógeno principal, posiblemente por un mecanismo mediado por aumento del estrés oxidativo. Las poliaminas espermidina y espermina revierten casi completamente los efectos dismorfogénicos que la glucosa causa, sin cambio aparente en la actividad de enzimas depuradoras. El presente estudio se realizó para tratar de dilucidar cambios en la inmunoexpresión de las enzimas antioxidantes por efecto de glucosa y poliaminas. Se cultivaron embriones postimplantacionales de rata en presencia de glucosa con o sin poliaminas, y se recuperaron para ser cortados al micrótomo de rotación; las laminillas fueron sometidas a inmunohistoquímica para las enzimas catalasa, SOD-1 y SOD-2, y se observaron al microscopio. Los resultados indican que puede haber cambio en la inmunoexpresión de las enzimas depuradoras de radicales libres durante la dismorfogénesis embrionaria, y que las poliaminas pueden evitar parcialmente estos efectos.Diabetes mellitus plus gestation produces malformations, delay of development and loss of pregnancy. Apparently, glucose is the main teratogen, possibly by a mechanism mediated by increased oxidative stress. The polyamines spermidine and spermine almost completely reversed the dysmorphogenic effects of glucose without change in the activity of scavenging enzymes. The present study was carried out to try to elucidate the changes in immunoexpression of enzymes by effect of glucose and polyamines. Postimplantational rat embryos were incubated in the presence of glucose with or without polyamines, and were recovered, fixed, dehydrated, and sectioned in a rotation microtome; the sections were subjected to immunohistochemistry for catalase, SOD-1 and SOD-2, and were observed under the microscope. The results indicate that there may be change in the immunexpression of these enzymes during the embryo dysmorphogenesis, and polyamines could partially prevent these effects

Salud de los trabajadores

Actividad física y su relación con los factores de riesgo cardiovascular de carteros chilenosAnálisis de resultados: riesgos psicosociales en el trabajo Suceso-Istas 21 en Cesfam QuellónAusentismo laboral por enfermedades oftalmológicas, Chile 2009Brote de diarreas por norovirus, posterremoto-tsunami, Constitución, Región del MauleCalidad de vida en profesionales de la salud pública chilenaCaracterización del reposo laboral en personal del SSMN durante el primer semestre de 2010Concentración de nicotina en pelo en trabajadores no fumadores expuestos a humo de tabaco ambientalCondiciones de trabajo y bienestar/malestar docente en profesores de enseñanza media de SantiagoDisfunción auditiva inducida por exposición a xilenoErgonomía aplicada al estudio del síndrome de dolor lumbar en el trabajoEstimación de la frecuencia de factores de riesgo cardiovascular en trabajadores de una empresa mineraExposición a plaguicidas inhibidores de la acetilcolinesterasa en Colombia, 2006-2009Factores de riesgo y daños de salud en conductores de una empresa peruana de transporte terrestre, 2009Las consecuencias de la cultura en salud y seguridad ocupacional en una empresa mineraPercepción de cambios en la práctica médica y estrategias de afrontamientoPercepción de la calidad de vida en la Universidad del BiobíoPesos máximos aceptables para tareas de levantamiento manual de carga en población laboral femeninaRiesgo coronario en trabajadores mineros según la función de Framingham adaptada para la población chilenaTrastornos emocionales y riesgo cardiovascular en trabajadores de la salu

Avoiding overvoltage problems in three-phase distributed-generation systems during unbalanced voltage sags

This paper is a postprint of a paper submitted to and accepted for publication in IET Power Electronics and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at the IET Digital Library.During voltage sags, distributed generation systems must fulfil specific grid-code requirements for reactive current injection. This ancillary service can produce overvoltage problems in networks operating in unbalanced conditions when the amplitude of one of the phase voltages is higher than the others and a balanced reactive current is injected through large grid impedance. This study proposes a control scheme to avoid these overvoltage problems, thus reducing the risk of cascade disconnection that this incident may produce. The derivation of the control scheme starts from the flexible oscillating-power control, introduces the necessary modifications so that this control meets the grid-code requirements for current injection and combines it with a slope voltage control to achieve a good voltage regulation. A theoretical analysis is included to determine the expressions that quantify the voltage support characteristics of the proposal. Finally, selected experimental results are reported to validate the characteristics of the proposed control.Peer Reviewe