RESUMO: Operculina macrocarpa L. Urb é uma espécie conhecida popularmente como batata de purga, uma trepadeira da família Convolvulaceae que possui propriedades medicinais. O cultivo in vitro poderá contribuir para a produção de mudas em larga escala, favorecendo seu processo de comercialização. Assim, este trabalho teve como objetivo ajustar protocolos existentes para o estabelecimento in vitro e avaliar o efeito da interação de reguladores de crescimento sobre a morfogênese in vitro de O. macrocarpa. No processo de estabelecimento in vitro, foram testados: meio de cultura 1x MS sem carvão ativado, meio 1x MS com 1g.L-1 de carvão, meio 1/2x MS (com 50% da concentração de nutrientes) sem carvão e meio 1/2x MS com 1g.L-1 de carvão. Além do carvão ativado, foi testado o efeito do Ácido giberélico (GA3) nas seguintes condições: meio de cultura 1x MS sem GA3, meio 1x MS com 20μM de GA3 e meio 1x MS com 40 μM de GA3. Após o estabelecimentoin vitro, foram realizados ensaios com diferentes reguladores de crescimento. Inicialmente foram avaliadas diferentes concentrações de BAP com três diferentes segmentos da planta (basal, mediana e apical). Em seguida, foram testadas diferentes combinações com ANA x BAP e ANA x KIN. O delineamento experimental foi inteiramente casualizado. Os resultados obtidos permitem afirmar que é possível o estabelecimento e a multiplicação in vitro de O. macrocarpa utilizando a semente e a base do caule, respectivamente, como fonte de explante, em meio MS na presença e ausência de BAP. RESUMO L purga medicinais escala comercialização Assim testados ativado 1g.L1 1gL1 gL 1g.L 1 1g g 1g.L- 12x 2x 50 nutrientes GA (GA3 condições 4 basal, basal (basal apical. apical . apical) seguida KIN casualizado caule respectivamente explante L1 1gL 5 (GA

ABSTRACT: Operculina macrocarpa L. Urb is a species popularly known as purge potato, a climbing plant from the Convolvulaceae family that has medicinal properties. In vitro cultivation could contribute to the production of seedlings on a large scale, favoring its commercialization process. This this study adjusted existing protocols for in vitro establishment and evaluated the effect of the interaction of growth regulators on the in vitro morphogenesis of O. macrocarpa. In the in vitro establishment process, the following were tested: 1x MS medium without activated charcoal, 1x MS medium with 1g.L-1 of charcoal, 1/2x MS medium (with 50% of the nutrient concentration) without charcoal and 1/2x MS medium with 1g.L-1 of charcoal. In addition to activated charcoal, the effect of gibberellic acid (GA3) was tested under the following conditions: 1x MS medium without GA3, 1x MS medium with 20μM of GA3 and 1x MS medium with 40 μM of GA3. After establishment in vitro, trials were carried out with different growth regulators. Initially, different concentrations of BAP were evaluated with 3 different segments of the plant (basal, median and apical). Different combinations of ANA x BAP and ANA x KIN were then tested. The experimental design was entirely randomized. The results obtained showed that it is possible to establish and multiply O. macrocarpa in vitro using the seed and the base of the stem, respectively, as a source of explant, in MS medium in the presence and absence of BAP. ABSTRACT L potato properties scale process O 1g.L1 1gL1 gL 1g.L 1 1g g 1g.L- 12x 2x 50 concentration GA (GA3 conditions 4 Initially basal, basal (basal apical. apical . apical) randomized stem respectively explant L1 1gL 5 (GA

Abstract: In times of constitutional changes -the processes, never ends- it is always necessary to resort to the justifications that support the presence of state elements in the institutional framework. One of the most questioned (especially due to the against majority objection) is the constitutional jurisdiction, that is, the existence of an entity with the power to purge the norms that contravene what is predisposed by the fundamental charter. This questioning is not recent, but it harbors dilemmas such as its existence or the responsibility of who will carry it out. The present work, although it is written by a jurist, tries to bring arguments to the social sciences to reflect about the origin and future of the Constitutional Courts.

Resumen: En tiempos de cambios constitucionales -los procesos, como tales, jamás terminan- siempre es necesario acudir a las justificaciones que sustentan la presencia de las instituciones estatales dentro del andamiaje institucional. Una de las más cuestionadas (especialmente por la objeción contra mayoritaria) es la jurisdicción constitucional, esto es, la existencia de un ente con capacidad de depurar las normas que contravengan lo predispuesto por la carta fundamental. Este cuestionamiento no es reciente, sino que alberga dilemas tales como su existencia o la responsabilidad de quién lo desempeñará. El presente trabajo, si bien es escrito por un jurista, se empeña en dispensar argumentos a las ciencias sociales para reflexionar en torno al origen y futuro de los Tribunales Constitucionales.

RESUMO: Diferentes tratamentos de resfriamento são utilizados antes da estocagem das carnes. O efeito da aspersão de carcaças (SC) na qualidade da carne parece variar. Neste estudo, investigou-se os efeitos da aspersão de carcaças bovinas na perda de peso e na qualidade da carne durante subsequente estocagem. O programa de aspersão testado foi de um tempo total de 2 h, com uma aspersão inicial de 180 s, seguida por ciclos de aspersão de 60 s em intervalos de 540 s. Os cortes comerciais desossados “Peixinho” (IMPS 116B) foram embalados a vácuo e estocados por até 60 dias. Foram avaliadas as perdas por exsudação e cozimento, força de cisalhamento por Warner-Bratzler, cor da carne (CIE L*, a*, b*) e qualidade microbiológica. SC reduziu a perda de peso da carcaça (P < 0,001) em comparação com o resfriamento convencional. No entanto, o tempo de estocagem influenciou a perda por exsudação, por cozimento e força de cisalhamento. Os valores de CIE a* e b* aumentaram (P < 0,05) após 30 dias de maturação em ambos os tratamentos de resfriamento. O crescimento pronunciado de psicrotróficos foi observado durante a estocagem em ambos os tratamentos. Em conclusão, o SC pode ser usado para reduzir as perdas econômicas associadas ao resfriamento da carne, sem afetar os atributos de qualidade da carne.

ABSTRACT: Different chilling treatments are used before meat storage. The effect of spray chilling (SC) on meat quality appears to vary. Here, we investigated the effects of SC on beef carcass weight loss and meat quality during subsequent storage. The 2-h SC program tested involved 180-s initial spraying, followed by 60-s spray cycles at 540-s intervals. Deboned chuck tender (IMPS 116B) beef cuts were vacuum-packaged and stored for up to 60 d. Purge and cooking losses, Warner-Bratzler shear force, meat colour [CIE L*, a*, b*], and microbiological quality were evaluated. SC reduced carcass weight loss (P<0.001) compared with conventional chilling. However, storage time affected the purge and cooking losses, and Warner-Bratzler shear force. CIE a* and b* values increased (P<0.05) after 30-d aging in both chilling treatments. Pronounced psychrotrophic growth was observed during storage after both treatments. In conclusion, SC can be used to reduce the economic losses associated with meat chilling, without affecting meat quality attributes.

ABSTRACT. The study investigated meat quality of bulls fed concentrate feeds and hay. The treatments were hay ad libitum + dried cafeteria leftover 4 kg DM d-1 (D1); hay ad libitum + wheat bran 4 kg DM d-1 (D2); hay ad libitum + 4 maize grain 4 kg DM d-1 (D3); hay ad libitum + mix 4 kg DM d-1 (1:1, wheat bran to maize grain, respectively (D4)); hay ad libitum + scrambled whole groundnut 4 kg DM d-1 (D5); and hay ad libitum + mix of each ingredient 4 kg DM d-1(D6)). Samples from longissimus lumborum muscle were taken in triplicate. Beef from bulls fed D5 had highest (p < 0.05) protein and fat than those fed other treatments. However, bulls finished in D3 had similar fat to those fed with whole ground nut. Highest meat tenderness (p < 0.05) recorded at 24th followed by 16th d than those aged on other periods. Beef from D6 produced lean meat, which is acceptable to consumer and market demand than D3, produced carcass with highest fat coverage This study confirmed that meat from D6 had an acceptable quality attribute suggesting the breed could serve as a potential source in red meat industry.

The aim of this research was the replacement of conventional sample extraction techniques for polycyclic aromatic hydrocarbons (PAH) in tissue samples for a reliable, fast and eco-friendly procedure. The method was developed using a pressurized solvent extraction method and assessing two different standard reference materials (fish and mussel) and freeze-dried and fortified sardine samples (Sardinella sp.). Five different extraction procedures were evaluated and the best performance comprised 1 g of lyophilized tissue, 5 g of deactivated (5%) silica, a dichloromethane:methanol (4:1 v/v) mixture, a temperature of 80 °C, three cycles, 10 min of static time and 90 s of purge time. The method selected following these tests was further validated through the analysis of nine replicates of the National Institute of Standard and Technology (NIST) reference material No. 2976, resulting in an effective recovery of 83 ± 14%. The means and uncertainties attained for each PAH were equivalent to those of the reference material, corroborating the reliability of the developed method. A shorter processing time, less use of solvents and reagents and lower extract manipulation produced an effective method aligned with green-chemistry guidelines.

Resumen Se presenta evidencia de que un láser de helio-neón (He-Ne), que opera en el infrarrojo medio (MIR) a una longitud de onda de 3.39 µm, puede detectar variaciones de la concentración de 1-hexeno en presencia de catalizador sólido. La caracterización in situ y en línea de la concentración de 1-hexeno, un ejemplo de hidrocarburo, es importante para mejorar el entendimiento de la interacción entre la química y la hidrodinámica en procesos de reacción heterogénea. En esta investigación, se diseñó y construyó una unidad downer a escala de laboratorio. El reactor tiene una longitud de 180 cm, un diámetro interno de 1.3 cm y fue fabricado en cuarzo fundido para permitir el paso del rayo láser. El 1-hexeno se dosificó, se vaporizó y se introdujo en el reactor a través de dos entradas ubicadas en un ángulo de 45 grados desde el flujo descendente vertical y 70 cm por debajo de la entrada de un catalizador (0.5 g / s) y un flujo de 0.55 lpm de purga de N2 de arrastre. Un sistema de cinco calentadores, que se puede desplazar en dirección vertical para permitir el paso del rayo láser, garantiza temperaturas de hasta 823 K. Simulaciones de dinámica de fluidos computacional (CFD) de la hidrodinámica del sistema muestra que se alcanza un perfil de temperatura uniforme en la sección de reacción luego de la mezcla del catalizador con la alimentación. La relación estimada de catalizador a aceite y el tiempo en la corriente en los experimentos fueron de 0.4 a 1.3 y 2 s, respectivamente. Después de la corrección de la variación de potencia del láser, los resultados experimentales mostraron una respuesta lineal de la transmisión fraccional con la concentración de 1-hexeno que era independiente de la temperatura en el rango de 373 K a 673 K. Incluso en presencia de catalizador, la absorción de 1-hexeno en la frecuencia del MIR del láser utilizado en los experimentos es lo suficientemente alta como para permitir la detección de 1-hexeno ya que la absorción fraccional es cercana a cero para la longitud del camino de absorción (0.013 m) de estos experimentos y concentraciones de 1-hexeno superiores a 1.254 × 10-5 mol/cm3. La configuración experimental permitió demostrar la capacidad del sistema láser para medir la concentración de 1-hexeno incluso en presencia de un catalizador. Esto indica que es posible su uso para distinguir mejor el efecto de la hidrodinámica de la cinética en procesos de catálisis heterogénea.

Abstract This study provides evidence that a helium-neon (He-Ne) laser operating in the Mid-infrared (MIR) at a wavelength of 3.39 µm can detect variations in 1-hexene concentration in the presence of a solid catalyst. The in-situ and online characterization of the concentration of 1-hexene, as an example of a hydrocarbon, is relevant to enhance the current understanding of the interaction between hydrodynamics and chemistry in different heterogeneous catalytic processes. We designed and built a laboratory-scale downer unit that enabled us to analyze heterogeneous catalytic reactions and provided optical access. The lab-scale reactor was 180-cm long, had an internal diameter of 1.3 cm, and was made of fused quartz to allow the passage of the laser beam. 1-hexene was carefully measured, vaporized, and fed into the reactor through two inlets located at an angle of 45 degrees from the vertical descendent flow and 70 cm below the input of a solid catalyst and a purge flow entraining N2. A system of five heaters, which can be moved in the vertical direction to allow the passage of the laser beam, guaranteed temperatures up to 823 K. Computational Fluid Dynamics (CFD) simulations of the hydrodynamics of the system indicated that a uniform temperature profile in the reaction section was reached after the catalyst and the feed mixed. The estimated catalyst to oil ratio and time on stream in the experiments were, respectively, 0.4 to 1.3 and 2 s. After a correction for laser power drift, the experimental results showed a linear response of the fractional transmission to the 1-hexene concentration that was independent of temperature in the 373 K-673 K range. Even in the presence of a catalyst, the absorption of 1-hexene at the MIR frequency of the laser was high enough to enable the detection of 1-hexene since the fractional absorption of the absorbing path length in these experiments was close to zero (0.013 m) and the 1-hexene concentrations were higher than 1.254 × 10-5 mol/cm3. This result demonstrated the ability of the laser system to measure the concentration of 1-hexene in the presence of a catalyst and indicates that it can be used to better decouple hydrodynamics from kinetics in heterogeneous catalytic processes.

Resumen El artículo tiene como objetivo caracterizar el proceso de construcción histórica del extranjero pernicioso en el periodo que va desde 1894 hasta 1936 con el fin de mostrar como el mecanismo de expulsión fue utilizado como una herramienta política que buscaba controlar y depurar la inmigración en el país. Sobre todo, el texto defiende el argumento de que este mecanismo funcionó contra un segmento especifico de la población, la clase trabajadora, y su puesta en práctica muestra la intención de contener el asociativismo obrero, así como el desarrollo de ideas socialistas consideradas contrarias a la moral costarricense. Para fundamentar este planteamiento, se trabaja con fuentes primarias provenientes del Archivo Nacional de Costa Rica y el Archivo Histórico Nacional de España, seleccionando aquellos expedientes administrativos abiertos por el delito de perturbación de la tranquilidad pública y complementando el análisis con la legislación vigente sobre la temática y la bibliografía sobre conflictividad laboral. El estudio se concentra en las ciudades de San José y Limón por ser aquellas donde se concentran los casos la mayoría de órdenes de expulsión.

Abstract The article aims to characterize the process of historical construction of the pernicious foreigner in the period from 1894 to 1936 in order to show how the mechanism of expulsion was used as a political tool that sought to control and purge immigration in the country. Above all, the text defends that this mechanism worked against a specific segment of the population, the working class, and its implementation shows the intention to contain the worker’s associativism as well as the development of socialist ideas considered contrary to the national morality. To support this approach, the researcher worked with primary sources from the National Archive of Costa Rica and Historic National Archive of Spain, selecting those administrative files opened for the crime of disturbance of public tranquility and complementing the analysis with the current legislation on the subject and the literature on labor disputes. The study focuses on the cities of San José and Limón, which are the cities where the cases that were found are concentrated.

Abstract Objective: To analyze the impact of vacuum-assisted venous drainage (VAVD) on arterial pump flow in a simulated pediatric cardiopulmonary bypass circuit utilizing a centrifugal pump (CP) with an external arterial filter. Methods: The simulation circuit consisted of a Quadrox-I Pediatric oxygenator, a Rotaflow CP (Maquet Cardiopulmonary AG, Rastatt, Germany), and a custom pediatric tubing set primed with Lactated Ringer's solution and packed red blood cells. Venous line pressure, reservoir pressure, and arterial flow were measured with VAVD turned off to record baseline values. Four other conditions were tested with progressively higher vacuum pressures (-20, -40, -60, and -80 mmHg) applied to the baseline cardiotomy pressure. An arterial filter was placed into the circuit and arterial flow was measured with the purge line in both open and closed positions. These trials were repeated at set arterial flow rates of 1500, 2000, and 2500 mL/min. Results: The use of progressively higher vacuum caused a reduction in effective arterial flow from 1490±0.00 to 590±0.00, from 2020±0.01 to 1220±0.00, and from 2490±0.0 to 1830±0.01 mL/min. Effective forward flow decreased with increased levels of VAVD. Conclusion: The use of VAVD reduces arterial flow when a CP is used as the main arterial pump. The reduction in the forward arterial flow increases as the vacuum level increases. The loss of forward flow is further reduced when the arterial filter purge line is kept in the recommended open position. An independent flow probe is essential to monitor pump flow during cardiopulmonary bypass.

ABSTRACT We investigated the ability to predict production performance in Iberian pigs in an extensive production system from measurements of feed efficiency measured intensively. The second objective of this work was to study the relationship between feed efficiency and meat quality (composition, juiciness, tenderness, color, and subcutaneous fatty acid composition) and if cooked and cured quality properties can be predicted by properties in fresh meat. Thirty Iberian sows received successively a restricted diet of concentrate (P1concentrate) and acorns (P2acorn) intensively and an ad libitum diet of acorns supplemented with a restricted amount of concentrate (P3montanera) extensively. Pigs that were more feed efficient on concentrate were less feed efficient on acorns and had higher body weight gain during the montanera . Improved feed efficiency on acorns reduced the concentration of α-linolenic and linoleic fatty acid composition of subcutaneous fat. Faster body weight gain in montanera resulted in a desirable reduction in cooking loss and a reduction in palmitic acid content in subcutaneous fat, and a potentially undesirable reduction in meat redness. Tenderness in cooked or cured loin was not significantly related to tenderness in the raw product. Cooking loss was positively related to purge and centrifugal drip loss and to color coordinates a*24 and b*24 in raw samples. We conclude that feed efficiency and body weight gain may be improved in the traditional Iberian production system, with a positive effect on cooking loss but potentially resulting in paler meat.

Resumen Se realizaron soldaduras TIG en tuberías de acero inoxidable AISI 304 purgadas con argón, con 999, 500, 200, 100, 50, 25 y 10 ppm de oxígeno atmosférico en la cámara de purga para determinar si esto influye en la calidad superficial de la zona afectada por el calor (ZAC) en la parte interna de la tubería. En este estudio se realizaron ensayos mecánicos, análisis metalográfico y morfológico. Se determinó que los niveles de decoloración en la ZAC están directamente influenciados por la cantidad de oxigeno atmosférico presente en la purga, por lo que con cantidades entre 50 a 10 ppm se evidencia decoloraciones de acuerdo a las normas AWS D18.1 y AWS D18.2. Se evidenció buena resistencia en la junta soldada debido a que la falla se da en el metal base y no en la ZAC que no ha tenido influencia de la decoloración superficial que corresponde a 10 ppm.

Abstract TIG welding was performed on AISI 304 stainless steel pipes purged with argon, the amounts of atmospheric oxygen in the purge chamber analyzed in this work were 999, 500, 200, 100, 50, 25 and 10 ppm that used to determine as the amount of oxygen affects the superficial quality of the heat affected zone (HAZ) in the internal part of the pipe. In this study, mechanical tests, metallographic analysis and morphological study were carried out. We determined that the levels of discoloration in the HAZ are directly influenced by the amount of atmospheric oxygen present in the purge, with amounts between 50 to 10 ppm the discoloration is according to AWS D18.1 and AWS D18. 2 standards. While was evidenced good resistance in the welded joint because the failure occurs in the base metal and not in the HAZ which has not influence of surface discoloration corresponding to 10 ppm.

Resumen Objetivo: Evaluar diferentes fuentes de miel en la cría de larvas de Galleria mellonella para la producción masiva de nematodos entomopatógenos. Metodología: Se evaluaron las fuentes azúcar morena, miel de abeja, miel de panela, miel de purga y panela pulverizada en el desarrollo de las larvas de G. mellonella y su costo de producción en las dietas; igualmente se determinaron los ciclos de vida del insecto. Resultados: Las larvas alimentadas con la dieta en la que se utilizó miel de panela y panela pulverizada presentaron un desarrollo similar a las alimentadas con la dieta convencional (miel de abejas); sin embargo, las alimentadas con azúcar morena presentaron menor tiempo de duración del período huevo-adulto (59,5 días) y disminución en el costo de producción (22 % menos) que las alimentadas con la dieta convencional. Conclusión: El azúcar morena se presenta como una alternativa viable para reemplazar la miel de abejas en la dieta convencional, lo que se traduce en menor costo de producción de los nematodos entomopatógenos.

Abstract Objective: To evaluate different sources of honey in the larvae culture of Galleria mellonella for the massive production of entomopathogenic nematodes. Methodology: Brown sugar, honey of bees, raw sugar cane honey, purge honey and powdered raw sugar cane were evaluated for G. mellonella larvae culture as well as their cost in the diets; life cycle of the insect was also determined. Results: Larvae fed with raw sugar cane developed similarly to those who had the conventional diet (honey of bees). However, the period between egg-adult (59.5 days) and the cost of production (22% less) were reduced when brown sugar was used compared to the conventional diet. Conclusion: Brown sugar is a viable alternative to replace honey in conventional diets, which translates into lower production costs of entomopathogenic nematodes.

Under normal circumstances the church would function as an agent of change and transformation, but this article focuses on the church herself that needs radical change if she is to remain relevant in mission and ministry in this current era. Clericalism and the centralisation of hierarchical control can be identified as the root causes of institutional pathology and weakening collegiality. To address clericalism may require the adjustment of seminary training, as in the current system seminarians are nurtured in a sense of separateness, promoting male-ego and feed gender exclusivity and doctrinal self-righteousness. While the seminary was once an instrument of reform in the Catholic Church, established to counter problems such as clerical concubinage and illiteracy, but now it is no longer suitable as it has become the forum that breeds other problems. Priority attention should be paid to purge the church of rampant clericalism, discriminatory scapegoating of gay persons, marginalisation of free thinkers, exclusion of women priests, the perceived moral laxity of family life issues and reception of communion by divorced Catholics without the benefits of annulment. Discrediting the personal authority of the pope is hardly an enlightened option. What ought to be transformed is the centralisation of control and allowing increased localised dominion whereby crises such as sexual abuse scandals could be addressed and solved more speedily and liberally, and limit the need to go to the top for solutions. To wait for centralised, hierarchal structures to deal with urgent issues is not desirable, as speedy accountability is needed to address issues that hurt the church in its entirety.

Resumo Completando um ciclo de seis artigos, este texto apresenta análise descritiva da carreira de Leontiev entre 1936-7, no contexto das profundas transformações causadas pelo Decreto contra a Pedologia de 1936 e subsequente campanha pública contra o legado vigotskiano. Procura delinear o sentido dessa campanha na sinistra conjuntura dos Grandes Expurgos stalinistas e situar o principal texto de crítica de Leontiev a Vigotski. Trata de mudanças teóricas nas obras dos autores em relação com a imposição de um “puro e genuíno” marxismo-leninismo às ciências. Defendo que Leontiev confundiu o problema ontológico e epistemológico sobre a relação consciência-matéria, repercutindo as cisões stalinistas entre ambas. Ao afastar-se do legado de Vigotski, realizou uma inflexão dualista, objetivista e mecanicista no materialismo psicológico vigotskiano.

Abstract Closing out a set of six articles, this text presents a descriptive analysis of Leontiev’s career between 1936-7 in the context of the profound changes caused by the Decree against Pedology and subsequent public campaign against the Vygotskian legacy. This paper seeks to outline the meaning of this campaign within the sinister context of the Soviet Great Purge and place Leontiev’s main critical text of Vygotsky in the context of the enforcement of a “pure and genuine” Marxism-Leninism on the sciences. We claim that Leontiev confused the ontological and epistemological problem of the relationship of consciousness to matter, reflecting the Stalinist divisions between them. When Leontiev moved away from Vygotsky’s legacy, he pursued a dualist, objectivist, and mechanistic inflection of Vygotsky’s psychological materialism.

Abstract: In Ecuador the use of pesticides has been a problem due to the concentrations used are higher than the maximum allowable limits. The agencies that control this type of compounds do not have sophisticated technologies like tandem mass spectrometry or time of flight, and use the same equipment for different analysis. For these reason sometimes two columns are installed simultaneously, which consequently can be a problem with the maximum temperature that can use. The aim of this work was to develop a methodology to quantify 32 organochlorine pesticides by gas chromatography using electron capture detector and mass spectrometry with a low oven temperature. Different conditions of temperature ramp, stationary phase, injector temperature, carrier gas flow, purge flow and injection mode were evaluated. Only injector temperature and carrier gas flow had no effect on the peak area. Using a DB5-ms column and the same temperature ramp, 24 pesticides were separated. Although different oven temperature programs were tested, three pairs of pesticides shared the same elution time, but the identification was achieved using selected ion monitoring mode. The correlation coefficient of the calibration curves was greater than 0,99. The detection limits found were lower than the maximum residue levels allowed.

Resumen: El uso de pesticidas en Ecuador es muy amplio y las concentraciones utilizadas son superiores a los límites máximos permitidos. Las agencias que controlan este tipo de compuestos no cuentan con tecnología sofisticada como tiempo de vuelo, utilizando el mismo equipo para distintos análisis. Por esta razón, en algunos casos dos columnas son instaladas simultáneamente, lo que podría llegar a ser un problema con la temperatura máxima que se puede utilizar. El objetivo de este trabajo fue desarrollar una metodología que permita cuantificar 32 pesticidas organoclorados mediante cromatografía de gases utilizando los detectores de captura de electrones y espectrometría de masas con temperatura reducida. Se evaluaron diferentes condiciones de rampa de temperatura, fase estacionaria, temperatura del inyector, flujo del gas de arrastre, flujo de purga y tipo de inyección. Únicamente la temperatura del inyector y el flujo del gas de arrastre no tuvieron efecto sobre el área de los picos. Empleando la columna DB5-ms y una misma rampa de temperatura, se pudieron separar 24 pesticidas. Pese a que se emplearon distintos gradientes de temperatura, tres pares de pesticidas compartieron el mismo tiempo de retención, pero aplicando el monitoreo de iones seleccionados se logró identificarlos. El coeficiente de determinación de las curvas de calibración fue mayor a 0,99. Los límites de detección encontrados fueron menores a los límites máximos permitidos.

In this article, we examine discourses of entrepreneurship manifest in selected textbooks used in South African primary schools in the postapartheid era. While an attempt was made to purge school textbooks of discriminatory subject matter, the extent to which new powerful discourses have replaced apartheid ideology remains unknown. There is little dispute that school textbook content communicates subliminal messages about the world. Using critical discourse analysis, we reveal constituted and constitutive ideology at work in the textbooks under study. A dominant discourse that emerged was that individuals in society are responsible for their own economic sustainability despite prevailing and historic conditions of oppression and subjugation, and that entrepreneurship is a readily viable way to achieve economic emancipation because it naturally leads to wealth creation. It communicates as a subtle yet deliberate attempt by the state to displace its responsibility for the economic welfare of the individual citizen. The textbooks uncritically legitimate the values of the neoliberal market system. In this paper, we urge the development of a heightened sensitivity when teacher educators, teachers, and learners engage with such ideological persuasions.