Control de Robots Móviles con Incertidumbres Dinámicas usando Redes de Base Radial Rossomando, Francisco Guido; Soria, Carlos Miguel; Carelli Albarracin, Ricardo Oscar En este trabajo se presenta un control de seguimiento de trayectorias de robots móviles. La estructura de control propuesta combina un modelo de linealización por realimentación basado en el modelo cinemático nominal, y una red neuronal directa para el control dinámico adaptable. La dinámica del robot es aprendida por una red neuronal basadas en funciones de base radial (RN-FBR) en un circuito de realimentación adaptable, ajustando el peso y las funciones de base radial. Se muestra un análisis de estabilidad del sistema de neuro-control adaptable. Se comprueba que los errores de control están limitados en función de la aproximación de error de la RN-FBR, la cual se comprueba con resultados experimentales.

Estudio observacional naturalistico sobre la efectividad del tratamiento farmacológico en una cohorte de pacientes con demencia tipo Alzheimer; Naturalist observational study on effectiveness of drug treatment of a cohort of patients with Alzheimer type dementia Rojas, Galeno; Bartoloni, Leonardo Carlos; Serrano, Cecilia Mariela; Dillon, Carol; Allegri, Ricardo Francisco Introduction: Naturalistic studies in clinical practice present great utility to guide the decision making and allow to corroborate the experimental findings of clinical trials. In Argentine, there are not published data of this type of studies in Alzheimer's Disease (DTA) with cholinesterase inhibitors. Objective: To evaluate effectiveness of treatment with donepezil patients with DTA mild degree in clinical practice. Materials and methods: Observational study, not controlled and longitudinal of 24 weeks of follow up in the Laboratory of Memory of the Zubizarreta Hospital. Were selected patients treated with donepezil with diagnosis of probable or possible mild DTA according to DSM IV and NINCDS-ADRDA criteria. The global, cognitive and behavioural domains were evaluated and Caregiver Burden. Results: Were selected for the analysis 38 patients whose completed the follow up, They were 63,15% (n=24) probable DTA and 36,84% (n=14) DTA with vascular component. At the end of the follow up a significant change in memory, visuespacial skills and language was demonstrated. Significance in global, behavioural and Caregiver Burden was not demonstrated nor activities of daily life. A 10% presented improvement of 2 points in MMSE (50% stayed stable, 39% deteriorated) to the 6 months. The parkinsonism risk was duplicated at the end of the study. Conclusion: In this work, a smaller group of patients with mild DTA responded favorably to donepezil in cognitive domain.Half of the patients stayed stable in their MMSE.

Integrable systems and Poisson-Lie T-duality: A finite dimensional example Capriotti, Santiago; Montani, Hugo Santos We study the deep connection between integrable models and Poisson-Lie T-duality working on a finite dimensional example constructed on SL(2,C) and its Iwasawa factors SU(2) and B. We shown the way in which the Adler-Kostant-Symes theory and collective dynamics combine to solve the equivalent systems by solving the factorization problem of an exponential curve in SL(2,C). It is shown that the Toda system embraces the dynamics of the systems on SU(2) and B.

Proteomic profile regulated by the anticancer peptide CIGB-300 in non-small cell lung cancer (NSCLC) cells Rodríguez Ulloa, Arielis; Ramos, Yassel; Gil, Jeovanis; Perera, Yasser; Castellanos Serra, Lila; García, Yairet; Betancourt, Lázaro; Besada, Vladimir; González, Luis J.; Fernández De Cossio, Jorge; Sanchez, Aniel; Serrano, Joem M.; Farina, Hernán Gabriel; Alonso, Daniel Fernando; Acevedo, Boris E.; Padrón, Gabriel; Musacchio, Alexis; Perea, Silvio E. CIGB-300 is a proapoptotic peptide-based drug that abrogates the CK2-mediated phosphorylation. This peptide has antineoplastic effect on lung cancer cells in vitro and in vivo. To understand the mechanisms involved on such anticancer activity, the NCI-H125 cell line proteomic profile after short-term incubation (45 min) with CIGB-300 was investigated. As determined by 2-DE or 2D-LC-MS/MS, 137 proteins changed their abundances more than 2-fold in response to the CIGB-300 treatment. The expression levels of proteins related to ribosome biogenesis, metastasis, cell survival and proliferation, apoptosis, and drug resistance were significantly modulated by the presence of CIGB-300. The protein translation process was the most affected (23% of the identified proteins). From the proteome analysis of the NCI-H125 cell line, novel potentialities for CIGB-300 as anticancer agent were evidenced.

Changes in topsoil bulk density after grazing crop residues under no-till farming Fernández, Patricia Lilia; Alvarez, Carina Rosa; Schindler, Valeria; Taboada, Miguel Angel The grazing of crop residues during the winter in integrated crop-livestock systems can either increase soil bulk density (BD) by compaction or decrease BD by swelling, as a function of gravimetric soil water content (GW) during grazing. A field experiment was conducted from 2005 to 2008 to evaluate the BD response to grazing in a no-till silty loam soil (Typic Argiudoll) of the Pampas region of Argentina. Soil BD (core method), GW data and the calculated air volume (AV) were obtained from the 0-50mm and 50-100mm layers at different sampling times from ungrazed and grazed treatments. Over most of the study period (2006 through 2008) soil BD showed little impact from grazing, with minimal temporal variation (1.32-1.46Mgm-3). This stable behavior was ascribed to low rainfall and relatively low GW values at the time when soil was trampled by livestock and routinely trafficked by machinery. Soil BD in the upper (0-50mm) layer was significantly (p<0.001) lower at the beginning of the study (2005 to early 2006), when the rainfall was higher (as was soil GW) during transit periods. Lower BD was not due to soil swelling but to air that was trapped by kneading in response to transit of livestock and machinery. Fitted straight lines indicated that this process became particularly prominent when GW was >330gkg-1 in the ungrazed treatment and GW was >240gkg-1 in the grazed treatments. Grazing accentuated the soil kneading process that promoted air entrapment. Our results suggest in this no-tilled silt loam soil that winter grazing of crop residues caused no deterioration of topsoil porosity in the no-tilled silty loam soil.

La sexualidad en la red de los discursos mediáticos: Una lectura de la construcción de la educación sexual en la prensa argentina Boccardi, Facundo Gustavo La implementación de la educación sexual en las escuelas emerge como tema de la agenda mediática de la prensa argentina a comienzos del 2004. En este artículo, se recurre a los aportes teóricos de Michel Foucault y Judith Butler sobre la sexualidad para abordar los procedimientos discursivos de la prensa argentina en la construcción de la educación sexual como objeto.; The implementation of sex education in schools comes out as a topic for the media agenda of the press in Argentina in early 2004. In this paper, we use the theoretical contributions of Michel Foucault and Judith Butler on sexuality to address the discursive procedures of the press in Argentina in the construction of sex education as an object.

Experimental investigations on flashing-induced instabilities in one and two-parallel channels: A comparative study Marcel, Christian Pablo; Rohde, Martin; Van Der Hagen, Tim H. J. J. In this investigation, experiments conducted in a natural circulation test facility at low power and low pressure conditions, in the one single and two-parallel channels configuration are presented and discussed in detail. The novel manner of visualizing the results allowed characterizing the facility at any time and position which helped to thoroughly understand the instability mechanisms. Different modes were observed for each configuration. In the case of having two-parallel channels, four different behaviors have been observed: stable flow circulation, periodic high subcooling oscillations, a-periodical oscillations and out-of-phase periodical oscillations. In addition, stability maps were constructed in order to clarify the region in which each mode is dominant. The results obtained from both the one and two-parallel channels configurations are thus analyzed and compared. As a result, some similarities have been observed between the intermittent flow oscillations found in the single channel experiments and the high subcooling oscillations found in the two-parallel channels experiments. Moreover, similarities have also been found between the sinusoidal flow oscillations existing in the single channel experiments and the out-of-phase oscillations from the two-parallel channels experiments. The experiments presented in this work can be used to benchmark numerical codes and modeling techniques developed to study the start-up of natural circulation BWRs.

Infraestructura Ferroviaria y Ciudad. Modalidades urbanísticas de resolución de sus vínculos en la historia urbana de Santa Fe. Saus, María Alejandra Interpretaciones recientes abonan matices locales en la apropiación de ideas sobre la ciudad. Por ello es posible afirmar que el urbanismo en Argentina se constituyó por sucesivas mutaciones, delineándose como disciplina autónoma alrededor de 1910. A partir de entonces se perfiló una tradición unitaria, a pesar de los variados nombres que recibió durante el siglo XX. Tales denominaciones manifiestan modos de legitimación de una disciplina que se nutrió de los saberes de diversas ciencias. Sin embargo, las coyunturas históricas establecen quiebres epistemológicos, siendo un indicador de los mismos el abordaje de la inserción ferroviaria en la ciudad. Si el siglo XIX abrazó al ferrocarril como sinónimo de progreso, el urbanismo segregó las infraestructuras para liberar a la ciudad de un obstáculo. Recientemente, la reconversión de áreas ferroviarias por su valor cultural e histórico, vuelve a revelar cómo estas prácticas resuelven en idiomas diversos el diálogo histórico entre infraestructura y ciudad.

An Improved Control Strategy for Hybrid Wind Farms Leon, Enrique Andres; Mauricio, Juan Manuel; Gomez-Exposito, Antonio; Solsona, Jorge Alberto This paper addresses the control requirements of hybrid wind farms, comprising a relatively large number of conventional Induction Machines (IM) along with one or very few Permanent Magnet Synchronous Machines (PMSM), capable of compensating the reactive power demanded by the IMs during faulty conditions as well as attenuating the active power variations due to wind gusts. Based on the superposition theorem and the feedback linearization technique, a controller is designed to independently regulate the positive and negative sequence currents of the PMSM Voltage Source Converters (VSC), overcoming several drawbacks of existing approaches in the presence of unbalanced voltages. In the proposed scheme, the grid-side VSC currents are controlled in order to improve the ride-through capability of IMs, so that the whole wind farm can fulfill demanding grid codes in absence of extra equipment, such as STATCOMs. As shownby the test results, combining IM-based wind farms with PMSMs accomplishes several relevant goals: delivering the reactive power consumption of the IMs, increasing the rated active power of the installation and smoothing mechanical power oscillations.

El Plan del 80 en Santa Fe: regionalización tardía ante la suburbanización inminente Rausch, Gisela Ariana Se intenta una aproximación al Plan Urbano de 1980 de la ciudad de Santa Fe, el cual puede ubicarse dentro de la serie de planes con voluntad de regionalización, que tuvieron lugar en parte de Argentina entre las décadas del 40 y el 60. De publicación tardía, durante el gobierno de facto de 1976-1983, el Plan se alineaba con lo que se dio en llamar planificación integral. El abordaje del Plan tiene como objetivo principal volver la mirada hacia una herramienta de actuación urbana en la que por primera vez en la historia urbanística local se menciona la ocupación de las áreas periféricas de la ciudad. Cuestión que en los últimos años, frente el desborde suburbano que muchas ciudades intermedias argentinas han sufrido a partir de los 70, y en particular, frente al problema hídrico recurrente en Santa Fe, por la ocupación del valle del Paraná, continúa en mesa de debate.

Dieta de Lontra longicaudis (Carnivora, Mustelidae) en el Parque Nacional El Rey (Salta, Argentina) y su comparación con otras poblaciones de la cuenca del Paraná Chemes, Silvina Beatriz; Giraudo, Alejandro Raul; Gil Carbó, Guillermo Se analizó la dieta de Lontra longicaudis en el Parque Nacional El Rey, en la eco-región de las Yungas, noroeste argentino. Se compararon estos datos con los de poblaciones previamente estudiadas en la laguna Iberá (Esteros del Iberá) y en el río Iguazú (Selva paranaense) en el nordeste argentino. Se analizaron 130 heces colectadas en 37 sitios evaluando porcentaje de ocurrencia, frecuencia relativa, importancia relativa porcentual y diversidad de Levins. Se comparó con otras poblaciones mediante el índice de similitud porcentual, re-muestreo por bootstrap y análisis no paramétricos. De un total de 623 presas, Peces, Insectos y Crustáceos fueron más frecuentes que Anfibios, Moluscos, Reptiles y Mamíferos. La mayoría de las presas fueron organismos bentónicos. Nuestros resultados fueron más similares a uno de los estudios del Iberá. Otros dos estudios, del Iberá y del Iguazú, publicados por el mismo autor, fueron más semejantes entre sí. La adaptabilidad trófica de L. longicaudis a diferencias en disponibilidad y variación temporal de las presas o los sesgos metodológicos entre autores, podrían ser causas de las diferencias en las dietas de las poblaciones estudiadas en la cuenca del Paraná.

Orthogonally additive holomorphic functions of bounded type over C(K) Carando, Daniel Germán; Lassalle, Silvia Beatriz; Zalduendo, Ignacio Martin It is known that all k-homogeneous orthogonally additive polynomials P over C(K) are of the form P(x)= ∫Kxkdμ. Thus, x → xk factors all orthogonally additive polynomials through some linear form μ. We show that no such linearization is possible without homogeneity. However, we also show that every orthogonally additive holomorphic function of bounded type f over C(K) is of the form f(x)=∫Kh(x)dμ for some μ and holomorphic h : C (K) → L1(μ) of bounded type.

Chemoprophylactic activity of flubendazole in cystic echinococcosis Ceballos, Laura; Elissondo, María Celina; Sanchez Bruni, Sergio Fabian; Confalonieri, Alejandra; Denegri, Guillermo Maria; Alvarez, Luis Ignacio; Lanusse, Carlos Edmundo Background: Cystic echinococcosis (CE) is an important public health problem worldwide. Flubendazole, administered in tablets, has shown poor in vivo efficacy against CE in humans. However, flubendazole prepared as a solution caused a marked reduction in hydatid cysts developed in mice. The goal of the current work was to compare the chemoprophylactic effect of flubendazole formulated either as a hydroxypropyl-β-cyclodextrin solution or as a carboxymethylcellulose suspension in secondary CE in mice. Methods: Balb/C mice were infected with Echinococcus granulosus protoscoleces. One day after infection, the animals were allocated into 3 different experimental groups: unmedicated control and treated at the time point of infection with flubendazole either prepared as a solution or suspension given twice a day during 15 days. Six months after infection, the animals were sacrificed to collect and weight parasitic cysts. Cyst samples recovered from infected mice of each experimental group were prepared for both scanning and transmission electron microscopy. Results: Both flubendazole formul tions induced a significant reduction in cyst weight compared to the cysts recovered from the unmedicated control animals. Both formulations showed similar flubendazole-induced ultrastructural morphological changes. Conclusion: Flubendazole offers a great potential to become a drug of choice in the preventive treatment of cystic echinococcosis.

Total ozone and equatorial zonal wind Zossi Artigas, Marta Maria; Fernandez de Campra, Patricia Spatial correlations between total column ozone observed by TOMS and equatorial zonal winds from 1979 to 2003 have been assessed. Four months and three different altitude levels have been analyzed: January and July (solstice months), April and October (equinoctial months), and 10, 30 and 50. hPa. The results are different for the months and altitudes considered. The highest correlations values appear in tropical zone at 30. hPa. The Brewer-Dobson circulation plays a key role in regulating the abundance of ozone, influenced by the quasi-biennial oscillation (QBO) circulation. Since the Brewer-Dobson is a slow circulation, correlations considering lags between one and 12 months were estimated. In this case, the highest correlations values are moving to subtropical latitudes at winter hemisphere, with different behaviors for three altitude levels considered.

Entomofauna asociada a garbanzo en el noroeste de Córdoba (Argentina); Entomofauna associated to chickpea in northwest of Cordoba (Argentina) Avalos, S.; Mazzuferi, V.; Fichetti, P.; Berta, Dominga Carolina; Carreras, J El garbanzo es un cultivo que se desarrolla en invierno. Entre los factores bióticos que limitan su producción se señalan a los insectos. El objetivo de este trabajo fue determinar las especies y abundancia de insectos fitófagos y sus enemigos naturales, asociados a dos cultivares de garbanzo (Chañaritos S156 y Norteño) en el noroeste de Córdoba. Durante 2006-2007, desde julio a noviembre se recolectaron manualmente los insectos presentes en sus diferentes estados de desarrollo en 30 plantas de cada cultivar tomadas al azar, y hojas con síntomas de moscas minadoras. A partir de la cría de insectos fitófagos se obtuvieron parasitoides. Se determinaron 15 especies de fitófagos y nueve de enemigos naturales. Las comunidades de insectos en ambas cultivares se hallaron dominadas por Lepidoptera, siendo Heliothis virescens la especie más abundante. Se registraron cinco especies de áfidos (Hemiptera) destacándose por su abundancia Acyrtosiphon pisum, cuatro especies de Thysanoptera que constituyen la primera cita sobre garbanzo y Liriomyza sp. (Diptera: Agromyzidae) en hojas minadas. Entre los predadores se encontraron Coccinellidae (Coleoptera) y Reduviidae (Hemiptera). Los parasitoides Hymenoptera Ichneumonidae y Chalcididae emergieron de H. virescens; Braconidae de áfidos; Eulophidae de Liriomyza sp. y Scelionidae de huevos de chinches. Por la etapa del cultivo en que se encuentra, daño directo y abundancia H. virescens sería la especie más perjudicial en la zona de estudio. Deben profundizarse las investigaciones referentes al rol como plagas potenciales de las principales especies de fitófagos y la incidencia de sus controladores naturales.; The chickpea is a crop that grows in winter. Among the biotic factors that limit the production are the insects. The aim of this work was to determine the species and abundance of insect herbivores and its associated natural enemies to cultivars of chickpea (Chañaritos S156 and Norteño) in the northwest of Cordoba. During 2006-2007, from July to November, insects in different states of development were collected manually in thirty plants of each cultivar that were chosen, as well as leave with symptoms of leafminers. From the breading of insect herbivores, specimens of parasitoids were obtained. Fifteen species of herbivores and nine of natural enemies associated to them were determined. The communities of insects in both cultivars were dominated by Lepidoptera, being Heliothis virescens the most abundant species. Five species of aphids (Hemiptera) were collected and Acyrtosiphon pisum was the most abundant, four registered species of Thysanoptera constitute the first appointment on the chickpea and Liriomyza sp. (Diptera: Agromyzidae) in leaves mined. The predators were Coccinellidae (Coleoptera) and Reduviidae (Hemiptera). Parasitoids Hymenoptera: Ichneumonidae and Chalcididae emerged from H. virescens; Braconidae of aphids; Eulophidae of Liriomyza sp. and Scelionidae of eggs of bugs. Because the stage of the crop in which they are, direct damage and abundance H. virescens could be the most detrimental species in the zone of study. The research of the role of the potential pests of the main phytophagous insect species and the incidence of their natural enemies should be developed.

Manuscritos desde el dolor: ser mujer y marginal en una comunidad judía Cohen, Elisa Beatriz En Argentina los grupos migratorios judíos llegados desde finales del siglo XIX intentaron fuertemente integrarse al medio, destacando especialmente sus aportes positivos. La trata de blancas organizada por la organización judía Tzwí Migdal salpicaba la credibilidad comunitaria, de allí la necesidad de su erradicación. Este artículo estudia el discurso de una de esas mujeres, preservado porque al haber sido asesinada, el hecho derivó en la organización de un expediente penal. Aparecen allí dos cartas encontradas en la misma escena del crimen en las que es posible observar que su condición de mujer inmoral no obstaculiza el despliegue de un interior profundamente humano. De esta manera, estudiamos el discurso y el lenguaje y aplicamos herramientas que nos permiten avizorar el mundo interior de la marginación, la soledad y el desamparo.

Hydraulic parameters and longitudinal distribution of macroinvertebrates in a subtropical andean basin; Parámetros hidráulicos y distribución longitudinal de macroinvertebrados en una cuenca andina subtropical; Parâmetros hidráulicos e de macroinvertebrados distribuição longitudinal em uma bacia andina subtropical Mesa, Leticia Mariana Se estudió la influencia de variables hidráulicas, de sustrato y variables físico-químicas sobre la distribución espacial de ensambles de macroinvertebrados en once rápidos de una cuenca subtropical andina del noroeste de Argentina. Variables hidráulicas complejas (velocidad de fricción, rugosidad de la velocidad fricción, número de Reynolds, número limitante de Reynolds, fuerza de fricción), rugosidad de sustrato, y variables físico-químicas (temperatura del agua, conductividad y pH) fueron utilizadas en virtud de identificar aquellas significativamente relacionadas con la distribución de la comunidad de macroinvertebrados. La temperatura del agua, la conductividad y el pH presentaron valores más altos en los sitios de menor altitud, mientras que la rugosidad del sustrato, la velocidad y fuerza de fricción fueron mayores en los sitios de más altos. La abundancia total de macroinvertebrados fue mayor en los sitios de menor altitud, mientras que la diversidad de invertebrados disminuyó desde sitios superiores hacia los inferiores. Los cambios longitudinales en la hidráulica, rugosidad del sustrato y conductividad representan los factores de mayor incidencia en la distribución de los invertebrados bentónicos de la cuenca del Río Lules.; A influência de variáveis hidráulicas, substrato e variáveis físico-químicas sobre a distribuição espacial das assembléias de macroinvertebrados foi investigada em onze rápido do um bacia hidrográfica subtropical Andina do noroeste da Argentina. Variáveis hidráulicas complexas (velocidade de fricção, rugosidade da velocidade de fricção, número de Reynolds, número de Reynolds limitando e força de fricção), rugosidade do substrato, rugosidade relativa e variáveis físico-químicas (temperatura, condutividade e pH) foram utilizados com o objetivo de identificar aqueles significativamente relacionadas com a distribuição da comunidade de macroinvertebrados. A temperatura da água, condutividade e pH apresentaram os maiores valores em sitios de baixa altitude, enquanto a rugosidade do substrato, a velocidade de fricção e força fricção foram maiores nos locais de maior altitude. A abundância total de macroinvertebrados foi maior em locais mais baixa altitude, enquanto a diversidade de invertebrados diminuiu de superior para os locais mais baixos. Alterações longitudinais na hidráulica, rugosidade do substrato e condutividade são importantes fatores ao longo do qual a comunidade bentônica Río Lules bacia é distribuído.; The influence of hydraulic, substratum and physicochemical variables on the spatial distribution of macroinvertebrate assemblages was analyzed in eleven riffles in a subtropical Andean basin of Northwestern Argentina. Complex hydraulic variables (shear velocity, roughness shear velocity, inferred boundary Reynolds number, Reynolds number, Froude number, shear stress), substrate roughness, relative roughness, and physicochemical variables (water temperature, conductivity and pH) were used in order to identify those significantly related with the distribution of macroinvertebrate assemblages. Water temperature, conductivity and pH were significantly higher in lower altitude sites, whereas substrate roughness, shear velocity and shear stress increased in upper sites. Total macroinvertebrate abundance was higher in lower reaches, whereas invertebrate diversity decreased from upper to lower sites. Longitudinal changes in hydraulic variables, substrate roughness and conductivity represent the major factors affecting the benthic invertebrates distribution of Lules River basin.

Next-generation biofuels: Survey of emerging technologies and sustainability issues Zinoviev, Sergey; Müller-Langer, Franziska; Das, Piyali; Bertero, Nicolas Maximiliano; Fornasiero, Paolo; Kaltschmitt, Martin; Centi, Gabriele; Miertus, Stanislav Next-generation biofuels, such as cellulosic bioethanol, biomethane from waste, synthetic biofuels obtained via gasification of biomass, biohydrogen, and others, are currently at the center of the attention of technologists and policy makers in search of the more sustainable biofuel of tomorrow. To set realistic targets for future biofuel options, it is important to assess their sustainability according to technical, economical, and environmental measures. With this aim, the review presents a comprehensive overview of the chemistry basis and of the technology related aspects of next generation biofuel production, as well as it addresses related economic issues and environmental implications. Opportunities and limits are discussed in terms of technical applicability of existing and emerging technology options to bio-waste feedstock, and further development forecasts are made based on the existing social-economic and market situation, feedstock potentials, and other global aspects. As the latter ones are concerned, the emphasis is placed on the opportunities and challenges of developing countries in adoption of this new industry.An overview of technical aspects of production technologies for next-generation biofuel is presented. Complemented with their related economical and environmental assessment results, an insight into the sustainability of the technologies, and an analysis of the opportunities and limits of future development, is given. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Screening of optimal pretreatment and reaction conditions for the isomerization-cracking of long paraffins over Pt/WO3-ZrO2 catalysts Busto, Mariana; Grau, Javier Mario; Vera, Carlos Roman Pretreatment and reaction conditions for the isomerization-cracking of long paraffins over commercial Pt/WO3-ZrO2 catalysts were screened. Optimal conditions were seeked for the production of short, high octane branched paraffins for the gasoline pool. n-C16 was used as a model molecule. The reaction over the acidic catalyst was used to adjust the size of the molecules to the boiling range of gasolines and to add branching in order to increase the octane number of the product. These adjustments had to be done while minimizing the production of light gases and getting a stable activity level. With respect to the pretreatment it was confirmed that the best calcination temperature of the tungstate oxoanion promoted hydroxides was 800 °C. Optimality was mostly related to the activity level. The optimum temperature coincides with the appearance of small WO3 crystallites which are thought to be center for creation of Brönsted acid sites in the presence of platinum and hydrogen. Regarding the reaction conditions, increasing temperature values augmented the conversion but also increased the cracking. Therefore optimum values were found at moderate temperature given the high reactivity of the feed. Space velocity values were analyzed with attention to the liquid C5+ yield, the selectivity to branched isomers and the stability of the catalysts. Best yields to branched naphtha products were obtained with Pt/WO3-ZrO2 at WHSV = 18 h-1. The catalyst coking rate was a function of the H2/hydrocarbon ratio. A value of 6 was enough to attain a stable conversion value on Pt/WO 3-ZrO2. The values of liquid yield as a function of pressure displayed a volcano pattern that was rationalized in terms of a non-classical bifunctional mechanism of reaction. High pressure values increased the concentration of Brönsted acid sites and hence the activity. Too high pressures enhanced hydrocracking and decreased the liquid yield. The results indicate that in general terms Pt/WO3-ZrO2 at moderate reaction conditions transforms a paraffinic heavy cut into a branched isomerizate that can be added to the gasoline pool to improve the quality properties. It was however found that under some conditions the octane gain is inversely proportional to the yield of light gases indicating that a high RON isomerizate can only be got at the expense of the liquid yield.

Screening of optimal pretreatment and reaction conditions for the isomerization-cracking of long paraffins over Pt/WO3–ZrO2 catalysts Busto, Mariana; Grau, Javier Mario; Vera, Carlos Roman Pretreatment and reaction conditions for the isomerization-cracking of long paraffins over commercial Pt/WO3-ZrO2 catalysts were screened. Optimal conditions were seeked for the production of short, high octane branched paraffins for the gasoline pool. n-C16 was used as a model molecule. The reaction over the acidic catalyst was used to adjust the size of the molecules to the boiling range of gasolines and to add branching in order to increase the octane number of the product. These adjustments had to be done while minimizing the production of light gases and getting a stable activity level. With respect to the pretreatment it was confirmed that the best calcination temperature of the tungstate oxoanion promoted hydroxides was 800 °C. Optimality was mostly related to the activity level. The optimum temperature coincides with the appearance of small WO3 crystallites which are thought to be center for creation of Brönsted acid sites in the presence of platinum and hydrogen. Regarding the reaction conditions, increasing temperature values augmented the conversion but also increased the cracking. Therefore optimum values were found at moderate temperature given the high reactivity of the feed. Space velocity values were analyzed with attention to the liquid C5+ yield, the selectivity to branched isomers and the stability of the catalysts. Best yields to branched naphtha products were obtained with Pt/WO3-ZrO2 at WHSV = 18 h-1. The catalyst coking rate was a function of the H2/hydrocarbon ratio. A value of 6 was enough to attain a stable conversion value on Pt/WO 3-ZrO2. The values of liquid yield as a function of pressure displayed a volcano pattern that was rationalized in terms of a non-classical bifunctional mechanism of reaction. High pressure values increased the concentration of Brönsted acid sites and hence the activity. Too high pressures enhanced hydrocracking and decreased the liquid yield. The results indicate that in general terms Pt/WO3-ZrO2 at moderate reaction conditions transforms a paraffinic heavy cut into a branched isomerizate that can be added to the gasoline pool to improve the quality properties. It was however found that under some conditions the octane gain is inversely proportional to the yield of light gases indicating that a high RON isomerizate can only be got at the expense of the liquid yield.