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espanolEste articulo reporta la sintesis y caracterizacion de Bi1-xLuxFeO3 (x = 0.00, 0.02 and 0.04) producido por reaccion de estado solido, con el fin de evaluar la influencia del cation lutecio sobre las propiedades estructurales y magneticas de la ferrita de bismuto (BiFeO3). Las muestras fueron caracterizadas por difraccion de rayos X (DRX), microscopia electronica de barrido (MEB), espectroscopia de energia dispersiva de rayos X (EDX) y analisis magnetico por medio de magnetometria de muestra vibrante (VSM) en un rango de temperatura de 50 a 320 K. Los resultados obtenidos permitieron confirman la formacion de materiales cristalinos de estructura romboedrica, grupo espacial R3c (161), de morfologia definida y tamanos de particula entre 2.25 y 4.50 μm. La insercion de Lu3+ en la estructura provoco un aumento en la magnetizacion, la pureza de BiFeO3 y una disminucion en la temperatura de sintesis en comparacion con lo reportado en la literatura EnglishThis paper reports the synthesis and characterization of Bi1-xLuxFeO3 (x = 0.00, 0.02 and 0.04) produced by solid-state reaction, in order to evaluate the influence of lutetium on the structural and magnetic properties of bismuth ferrite (BiFeO3). The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and magnetic analysis by vibrating sample magnetometer (VSM) in temperature range from 50 to 320 K. The obtained results allowed to confirm the formation of crystalline materials of rhombohedral structure, space-group R3c (161), with defined morphology and particle sizes between 2.25 and 4.5 μm. The Lu3+ insertion in structure generated an increasing in magnetization, purity of BiFeO3 and a decrease in the synthesis temperature compared with the reported in the literature

The effects of application of bovine urine on biomass and nitrogen (N) accumulation in 3 tropical grasses (Urochloa decumbens cv. Basilisk, U. humidicola cv. Humidicola and Megathyrsus maximus cv. Mombasa), and on available N concentrations in soil (NH4+-N, NO3--N) were studied using a randomized complete block design with 3 replicates. There were significant interactions between species and urine application over time in terms of herbage accumulation and N concentration (P

To establish the relationship between the intensity of the green color of leaves and their crude protein (CP) concentration in Urochloa brizantha, U. decumbens and U. humidicola pastures in the Piedemonte Llanero, Colombia, the leaf chlorophyll concentration was measured (in SPAD units), classified based on the Munsell color chart and compared with the leaf CP concentration determined by the Kjeldahl method. The regression analysis between chlorophyll and CP concentrations showed coefficients of determination (r2) between 0.76 and 0.88. While collection of additional data will allow colorimetric charts based on the Munsell color chart to be developed which can be used to predict CP levels for each of these species, the relationships generated can be used to develop recommendations to assist farmers in the region in their decisions on use and fertilizing of these pastures.

Several applications need a high power, high output voltage ac/dc converter. The structure includes a dc/dc resonant stage, which is fed from a three-phase line. Due to standards, rectified dc input voltage varies largely from 400 to 750 V affecting the adversely overall design and current levels. In fact, losses in the inverter become unbearable if both switching frequency and transferred power are desired beyond a certain level. In those cases, it is necessary to connect several switches in parallel. As an alternative, the new switches can configure a new modular structure instead, adding more flexibility in the control to compensate input voltage variations. As a result, the required circulating current is reduced to a half, with benefits in total power losses. Moreover, the nature of the topology allows a reconfiguration of the resonant net (LCC) for low power, reducing even further the minimum circulating current under those conditions (fluoroscopy, for instance). In this paper, the new multilevel resonant topology is mathematically modeled and proposed for radiography and fluoroscopy. An example illustrates the design procedure for a given application at 100 kW, 50–150 kV.

Este manual sintetiza recomendaciones, consideraciones y conceptos técnicos para la multiplicación de semilla del cultivar Veranera, conservando sus cuatro atributos de calidad: genética, física, fisiológica y sanitaria. Esta información se pone a disposición de agricultores, asistentes técnicos y personas relacionadas con el sector agropecuario de la región que estén interesados en la propagación de este cultivar como una opción nutricional para sus sistemas productivos. Las recomendaciones técnicas descritas en este manual favorecen y dinamizan la producción de semilla de calidad y contribuyen significativamente al sistema de producción de leguminosas forrajeras para los Llanos Orientales de Colombia.

An A. nidulans strain with a pyridoxine marker was used for continuous production of aryl alcohol oxidase (AAO) in a trickle bed reactor (TBR). Modified medium with reduced zinc, no copper, and 5 g/L ascorbic acid that reduced melanin production and increased AAO productivity under growth limited conditions was used. Two air flow rates, 0.11 L/min (0.1 vvm) and 1.1 L/min (1.0 vvm) were tested. More melanin formation and reduced protein productivity were observed with air flow rate of 1.1 L/min. Three random packings were used as support for the fungus inside the TBR column, two of which were hydrophobic and one which was hydrophilic, and three different dilution rates were tested. The use of GEA BCN 030 hydrophobic packing resulted in greater AAO yield and productivity than the other packings. Increasing dilution rates favored melanin formation and citric, lactic and succinic acid accumulation, which decreased AAO yield and productivity.

The hybrid gasification-syngas fermentation platform can produce more bioethanol utilizing all biomass components compared to the biochemical conversion technology. Syngas fermentation operates at mild temperatures and pressures and avoids using expensive pretreatment processes and enzymes. This study presents a new process simulation model developed with Aspen Plus® of a biorefinery based on a hybrid conversion technology for the production of anhydrous ethanol using 1200tons per day (wb) of switchgrass. The simulation model consists of three modules: gasification, fermentation, and product recovery. The results revealed a potential production of about 36.5million gallons of anhydrous ethanol per year. Sensitivity analyses were also performed to investigate the effects of gasification and fermentation parameters that are keys for the development of an efficient process in terms of energy conservation and ethanol production.

The present study evaluated butanol production from switchgrass based on hydrothermolysis pretreatment. The inhibitors present in the hydrolyzates were measured. Results showed poor butanol production (1g/L) with non-detoxified hydrolyzate. However, adjusting the pH of the non-detoxified hydrolyzate to 6 and adding 4 g/L CaCO3 increased butanol formation to about 6g/L. There was about 1g/L soluble lignin content (SLC), and various levels of furanic and phenolic compounds found in the non-detoxified hydrolyzate. Detoxification of hydrolyzates with activated carbon increased the butanol titer to 11 g/L with a total acetone, butanol and ethanol (ABE) concentration of 17 g/L. These results show the potential of butanol production from hydrothermolysis pretreated switchgrass.

Eastern redcedar is an invasive softwood species in Oklahoma and across grasslands in the Central Plains of the United States and potential feedstock for butanol production. Butanol has higher energy content than ethanol and can be upgraded to jet and diesel fuels. The objective of this study was to develop a process for production of butanol from redcedar. Results showed that Clostridium acetobutylicum ATCC 824 and Clostridium beijerinckii NCIMB 8052 did not grow in fermentation medium with citrate buffer. However, both strains grew in the medium with acetate buffer, resulting in 3–4 g/L greater butanol than without acetate. Detoxification of redcedar hydrolyzate was required to increase butanol concentration from 1 to 13 g/L. Hydrolyzate was detoxified by activated carbon to remove inhibitors. Fermentations in detoxified redcedar hydrolyzate reached 13 g/L butanol and 19 g/L total ABE, comparable to glucose control. This shows the potential for redcedar use in butanol production.

An Aspergillus nidulans cell factory was genetically engineered to produce an aryl alcohol oxidase (AAO). The cell factory initiated production of melanin when growth-limited conditions were established using stationary plates and shaken flasks. This phenomenon was more pronounced when the strain was cultured in a trickle bed reactor (TBR). This study investigated different approaches to reduce melanin formation in fungal mycelia and liquid medium in order to increase the enzyme production yield. Removal of copper from the medium recipe reduced melanin formation in agar cultures and increased enzyme activities by 48% in agitated liquid cultures. Copper has been reported as a key element for tyrosinase, an enzyme responsible for melanin production. Ascorbic acid (0.44 g/L) stopped melanin accumulation, did not affect growth parameters and resulted in AAO activity that was more than two-fold greater than a control treatment with no ascorbic acid.

We study organisational forms in conflict-ridden zones of rural Colombia and analyse the impact of violence and subjective perceptions of insecurity on the choice of organisational modes. Based on ...

Power supplies for medical X-ray applications must be designed to operate under very different conditions. The converter must be designed to deliver the maximum required power, which usually results in poor efficiency at low power levels. A new multilevel structure is proposed to minimize this problem. It is based on the series-parallel resonant topology (LCC) where a new auxiliary transformer has been added.

In this paper a mathematical model for a resonant multilevel converter is presented. The topology has been conceived to be used in X-ray power supplies. The power stage has been designed to minimize the resonant current throughout the input voltage range: 400V to 750V. The inverter stage is based on the series-parallel resonant topology, LCC, to include the parasitic elements of the step-up transformer. However, the introduction of an additional magnetic coupling provides a way to modify the reactive elements depending on the output power.

Aryl alcohol oxidase (MtGloA) is an enzyme that belongs to the ligninolytic consortium and can play an important role in the bioenergy industry. This study investigated production of an MtGloA client enzyme by a mutant strain of Aspergillus nidulans unable to synthesize its own pyridoxine. Pyridoxine limitation can be used to control cell growth, diverting substrate to protein production. In agitated culture, enzyme production was similar when using media with 1 mg/L and without pyridoxine (26.64 ± 6.14 U/mg mycelia and 26.14 ± 8.39 U/mg mycelia using media with and without pyridoxine, respectively). However, the treatment lacking pyridoxine had to be supplemented with pyridoxine after 156 h of fermentation to sustain continued enzyme production. Use of extremely diluted pyridoxine levels allowed reduced fungal growth while maintaining steady enzyme production. Concentrations of 9 and 13.5 µg/L pyridoxine allowed MtGloA production with a growth rate of only 5% of that observed when using the standard 1 mg/L pyridoxine media.

Subjective well-being (SWB), the evaluation that people carry out of their lives, has been proposed as an alternative measure of tracking the development of communities instead of economic growth. As part of a more general research question, in which we tested the impact of subjective insecurity on the choice of hybrid organizational modes, we hypothesized that subjective insecurity does negatively correlate with SWB and that subjective and objective insecurities are not significantly correlated. Subjective insecurity consisted of three items: perceptions of political, economic, and communitarian insecurity. We proposed that the relationship between insecurity and SWB is moderated by the level of social capital found in the region. Social capital was defined as interpersonal trust as well as the frequency of participation of producers in voluntary associations. We used multiple and multilevel regression models to test the hypotheses. Based on a survey of 742 rural producers in five conflicted areas, we found that the perceptions of insecurity do correlate significantly (negatively) with levels of SWB and we also found a significant contribution of social capital to levels of SWB. Significant correlations between demographic variables and SWB corroborated results of previous research. These results have important implications for public policy and future research.

Abstract. This article examines how the European Union (EU) has contributed to Security Sector Reform (SSR) in Georgia. SSR is a relatively new concept, which aims at creating a secure environment that is linked with democratic norms and institutions and which encompasses all the sectors and actors related to a state’s security and not only defence or intelligence forces. The European Security Strategy (ESS) identifies SSR as one of the main new possible missions of the EU’s foreign policy. Looking at the diverse EU programmes undertaken in Georgia and norms transference, the paper evaluates to what degree the EU has contributed to Georgian SSR, especially since the 2003 Rose Revolution. It is argued that in SSR the EU acts mainly as a ‘transmission belt’ of international norms and through bilateral ad hoc programmes. These results also show how the EU has increased its profile as a security provider, especially in the support of Georgian border management, and how the EU can become a security provider in areas of soft security such as judicial and law enforcement or police reform.

Se diseñó y desarrolló una herramienta informática (Manejo Experto de praderas: MEP-2) para simular el comportamiento de las gramíneas tropicales frente al pastoreo con bovinos y para establecer los períodos de uso y recuperación de las praderas, en función de la producción de biomasa comestible, su calidad y consumo por parte de los animales. Así mismo, MEP-2® incorpora variables de calidad del forrraje y de distensión del rumen, de acuerdo con un modelo de simulación de consumo de materia seca (MS) simple y de fácil implementación. EI sistema fue estructurado previamente en hoja de cálculo y posteriormente trasladado a Visual Basic 6™; la información de identificación de la finca, tipo de ganado, especies de pastos y sistema de pastoreo se almacenó en formato Access™. El programa consta de seis ventanas que se abren secuencialmente una vez se diligencia la información solicitada: dos ventanas corresponden a la evaluación de la disponibilidad de forraje según el tipo de gramínea: erecta o postrada. Otras dos ventanas registran información de la finca y las praderas con sus características individuales. De las dos ventanas finales, una corresponde a los resultados de la simulación y la otra a su interpretación, además de algunas recomendaciones generales. El propósito de la herramienta es proporcionar a ganaderos y asistentes técnicos un sistema objetivo para la toma de decisiones en el manejo de las praderas contribuyendo de esta manera a su sostenibilidad y a una mayor eficiencia de los animales.

Se evaluó un programa de computador diseñado para predecir la utilización de praderas con bovinos bajo diferentes sistemas de pastoreo en distintos escenarios y regiones de Colombia y se compararon las predicciones de disponibilidad de biomasa, tiempos de pastoreo y de recuperación contra los datos observados en cada una de las fincas. Se incluyeron una finca en el Valle del Cesar con vacas doble propósito secas bajo pastoreo rotacional en praderas de pasto Guinea, una finca en el Piedemonte del Meta con novillos de ceba bajo pastoreo alterno de Brachiaria decumbens, una finca en el Magdalena Medio santandereano con novillos de ceba en pastoreo rotacional de Brachiaria humidícola y una finca en la Sabana de Bogotá con vacas de ordeño bajo pastoreo de Kikuyo-Ryegrass en franjas de un día. En cada una de las fincas se evaluaron dos rotaciones completas en cada época climática (sequía, lluvias). El análisis de las predicciones contra las observaciones en las variables días de ocupación, descanso y disponibilidad de forraje, se realizó mediante una comparación de medias con prueba de "t" (a de 5%). El consumo animal de MS predicho por el programa se analizó en relación con variables de calidad del forraje: proteína cruda, digestibilidad y Fibra en Detergente Neutro, mediante regresión lineal simple, encontrándose una correlación media para las tres variables con el consumo. Se concluye que el programa de simulación ayuda a la toma de decisiones sobre manejo de praderas, con mayor precisión durante la época de lluvias, mientras que Para la época seca/ los resultados deben tomarse con precaución realizando una evaluación o aforo de las praderas cuidadosa.

This study investigated the effect of two wood zones (sapwood versus heartwood) and size reduction techniques [Crumbles® (Crumbles® is a registered trademark of Forest Concepts, LLC, Auburn, WA, USA) particles versus ground particles] on wood glucan-to-ethanol yield after acid bisulfite pretreatment and simultaneous saccharification and fermentation (SSF) of Eastern redcedar. SSFs were conducted at 8% solids loading ( w / w dry basis) using Accellerase® 1500 at a loading of 46 FPU/g glucan and Saccharomyces cerevisiae D 5 A for ethanol fermentation. The size reduction technique had no effect on ethanol yield. However, sapwood glucan-to-ethanol yields were significantly greater than heartwood yields. The highest wood glucan-to-ethanol yield of 187 L/dry Mg (95% of theoretical) was achieved with sapwood crumbled particles in 240 h. Ground sapwood, crumbled heartwood and ground heartwood achieved ethanol yields of 89%, 81% and 80% of theoretical in 240 h, respectively. Preliminary mass balances showed 100% glucan recovery with crumbled sapwood and extensive (72%) delignification.

El aprendizaje organizacional es relevante en el contexto actual de la economía global, dado que las organizaciones cambian y se transforman a gran velocidad. Bajo estas condiciones, se ha dicho que sólo alcanzarán el éxito las empresas que de UII modo consistente sean capaces de aprender más rápido y mejor que sus competidoras, sea que creen un nuevo conocimiento o lo adquieran del entorno y que al difundirlo en su interior, lo incorporen rápidamente a las nuevas tecnologías .ti productos, reto que también enfrentan las organizaciones públicas. Bajo esta perspectiva se inicia una descripción de las características del aprendizaje organizacional en las entidades públicas del orden nacional en el Departamento de Bolívar, estableciendo los factores que afectan dicho aprendizaje y el conocimiento y análisis de sus causas e impactos relevantes en dichas instituciones. Al final se presentan las conclusiones generales y algunas propuestas para su mejoramiento.Palabras Clave: Aprendizaje Organizacional, Gestión Del Conocimiento, Sector Público, Factores Impulsores, Barreras, Formación y Desarrollo, Servidor Público, Competencias.