Más allá del productivismo capitalista: eficiencia y agricultura familiar en la reactualización de viejos debates teóricos de los estudios agrarios

En las discusiones históricas sobre el desarrollo agrario la agricultura actual ha sido imaginada por muchos como un sector moderno, con explotaciones homogéneas, grandes escalas de producción, uso intensivo de los insumos y una gran mecanización. Sobre esa misma línea argumentativa es que la desaparición de la pequeña producción fue predicada por décadas. Sin embargo el pequeño productor sigue ahí, para algunos resistiendo y adaptándose a un medio capitalista que lo agrede y busca subsumirlo; para otros representando la semilla de una forma alternativa de desarrollo. Este trabajo estudia la influencia que tuvo el concepto de eficiencia en este contexto y al mismo tiempo cuestiona la forma de utilizarlo y la validez de los resultados encontrados. Se señala que existieron ciertas limitaciones en la forma de abordar el tema, fundamentalmente basadas en la falta de evidencia empírica y en la forma en la que el concepto fue utilizado.In historical discussions about agricultural development, current agriculture has been imagined by many as a modern sector with homogeneous farms, large scales of production, intensive use of inputs and high mechanization. In the same line of argument, the disappearance of small production has been predicted for decades. However, small producers are still there, for some resisting and adapting to a capitalist environment that seeks to subsume and assault them, and for others representing the seed of an alternative form of development. This paper aims to study the influence of the efficiency concept in this context and at the same time question the validity of the findings. It emphasizes that there were some limitations in the way of addressing the issue, mainly based on the lack of empirical evidence and the way in which the concept was used.Fil: Rodriguez Sperat, Ramiro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Santiago del Estero. Facultad de Humanidades, Ciencias Sociales y de la Salud. Instituto de Estudios para el Desarrollo Social; ArgentinaFil: Jara, Cristian Emanuel. Universidad Nacional de Santiago del Estero. Facultad de Humanidades, Ciencias Sociales y de la Salud. Instituto de Estudios para el Desarrollo Social; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

High temperature treatments of porous activated carbon

The use of biomass waste for the preparation of activated carbon is of great industrial interest for reducing costs and increasing the sustainability, especially in the field of energy storage. A high temperature treatment is required to obtain a more ordered carbon material, thus increasing its conductivity. However, this high temperature treatment entails as a disadvantage a significant reduction in porosity. Therefore, a method to prepare activated carbons with a high porosity development as well as high conductivity could be of great interest for many applications. The aim of this work is to analyze the possible influence of phosphorus compounds on the physical-chemical properties of different carbon materials thermally treated at relatively high temperatures (1600 ºC). With this goal, it has been prepared activated carbons from different precursors (olive stone, lignin and hemp) and different conformations (powder, fibers and monoliths) by physical and chemical activation, with CO2 and H3PO4, respectively. Once the different activated carbon materials were prepared, they were thermally treated at 1600 ºC under inert atmosphere. The different samples were characterized by N2 and CO2 adsorption at 77 and 273 K, respectively, XPS, XRD and Raman techniques. The oxidation resistance was also evaluated in a thermogravimetric balance. High temperature treatments of activated carbon without the presence of P surface groups produced an important contraction of the porosity (from 900 to 150 m2 g-1). However, temperature treatments of phosphorus-activated carbon allowed for preparing carbon materials with a relatively high structural order and a well-developed porosity (c.a. 1100 m2 g-1), with a significant contribution of mesoporosity. These results suggest that these P-surface groups are responsible for the low contraction observed for the porous structure, avoiding, in a large extent, its collapse.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MINECO (CTQ2015-68654-R). MINECO (PTA2015-11464-I)

Methanol dehydration on carbon-based acid catalysts

Methanol dehydration to produce dimethyl ether (DME) is an interesting process for the chemical industry since DME is an important intermediate and a promising clean alternative fuel for diesel engines. Pure or modified γ-aluminas (γ-Al2O3) and zeolites are often used as catalysts for this reaction. However, these materials usually yield non desirable hydrocarbons and undergo fast deactivation. In this work, we study the catalytic conversion of methanol over an acid carbon catalyst obtained by chemical activation of olive stone with H3PO4. A significant amount of phosphorus remains over the catalyst surface after the activation process, mostly in form of C-O-PO3 and C-PO3 groups, which provide the carbon a relatively high surface acidity and oxidation resistance. Methanol decomposition on this catalyst yields selectivities to DME higher than 82% at 623K and methanol conversion of 34%, under the operating conditions studied. The activated carbon catalytic activity and stability, under inert and oxidant atmospheres, as well as different regeneration procedures, were studied. In the absence of oxygen, the catalyst suffers a progressive deactivation by coke deposition on the active acid sites (Fig. 1). The presence of oxygen modifies the carbon surface chemistry, probably through oxygen spillover on the catalyst surface, where the availability of labile oxygen avoids catalyst deactivation. A reaction mechanism has been proposed where methanol dehydration seems to proceed through an Eley-Rideal mechanism, which assumes the adsorption of water and oxygen spillover on the acid active sites, avoiding coke deposition

Modification of the morphology, porosity and surface chemistry of lignin-based electrospun carbon materials

Lignin is a biopolymer that can be found as the main component of plants. It is obtained as a coproduct in the papermaking and biofuel industries. Owing to its high carbon and aromatic content, high availability and reduced cost, it is an excellent precursor for the preparation of highly valued carbon materials. Electrospinning is a suitable top-down technique for the preparation of polymeric fibers using high voltage electrical fields and polymer solutions of proper viscosity and conductivity. Organosolv lignins, which are extracted from lignocellulosic biomass using organic solvents, are soluble in ethanol, obtaining a solution that matches the requirement of the electrospinning process. In this way, it is possible to produce lignin-based porous carbon fibers using a coaxial electrospinning device [1]. This contribution summarizes our findings about the preparation of carbon materials with different morphologies and composition by processing lignin using electrohydrodynamic forces. Lignin spheres, beaded fibers, straight fibers, beaded tubes and straight tubes are obtained by using coaxial and triaxial spinnerets that allows the electrospinning of two or three different solutions at once [1], Fig. 1. Thermal stabilization in air is needed in order to avoid melting of lignin fibers during carbonization. Stabilization times of 48-96 hours are usually required in this step, decreasing the sustainability of the production process. Phosphoric acid can be added in small amounts in the lignin solution, shortening the time for achieve a successful thermostabilization of the fiber [2]. The carbonized materials show narrow microporosity and large surface area values (SBET from 600 to 1000 m2g-1) and additional pore size and volume can be developed by controlled gasification.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. This work was supported by the Spanish Ministry of Economy and Competitiveness and FEDER (CTQ-2015-68654-R)

A Case of Cannabis Smoking Induced Leukocytosis

Background: Leukocytosis relates to infections, malignancies, stress response, and multiple intoxicants. Like other intoxicants, cannabis smoking can result in a persistent leukocytosis. Here we report a case of cannabis-induced leukocytosis. Case Presentation: A 20-year-old Hispanic female with a history of anxiety disorder presented with 3-days of nausea, vomiting, and colicky abdominal pain. She endorsed heavy marijuana smoking as self-medication and compulsive hot showers for symptom relief. She was admitted for oral intake intolerance, concerning for cannabis hyperemesis syndrome. Her history demonstrated multiple admission for cannabis hyperemesis syndrome during which she demonstrated a leukocytosis which improved with abstinence of marijuana. Her prior hematology workup was unremarkable. Upon admission, vital signs and physical exam were normal. Labs were significant for a neutrophil predominant (77.2%) leukocytosis (WBC: 26.2). The infectious workup including chest x-ray, urinalysis, blood cultures and inflammatory markers were unremarkable. Peripheral smear revealed a neutrophilic leukocytosis without blasts or immature cells attributable to inflammation. Off antibiotics her leukocytosis improved, her recovery was uneventful, and was discharged home. Conclusion: A neutrophil predominant leukocytosis can relate to heavy marijuana smoke inhalation. It has been suggested that pro-inflammatory chemicals and systemic inflammation generated from smoking marijuana cause these hematologic changes. Our case emphasizes considering heavy cannabis use among the differential for leukocytosis and recommending cannabis abstinence once other etiologies are ruled out

Valoração de uma experiência de intervenção com tecnologias socialmente apropriadas em Santiago del Estero (Argentina)

En el marco de las discusiones sobre el cambio tecnológico, las tecnologías socialmente apropiadas surgieron como una alternativa al modelo de transferencia modernizante que predominó durante muchos años en Latinoamérica. Sin embargo, a pesar del tiempo transcurrido desde su creación conceptual, no es sencillo encontrar estudios que valoren procesos de intervención realizados con este tipo de abordaje. Este trabajo busca aproximarse al tema mediante el análisis de una experiencia de estercolado de cultivos prediales con estiércol de cabra, en Santiago del Estero (Argentina). A pesar de contar con un diseño socialmente apropiado a priori, la tecnología no fue replicada por todos los experimentadores. Para abordarlo, se utilizó un enfoque cuantitativo y cualitativo de dos etapas: en la primera se prestó atención a las variables de estructura de cada experimentador y se hizo una correlación con las ocasiones en las que reiteró la práctica, y en la segunda se analizó el funcionamiento predial, mediante estudios de caso. Los resultados indican que una estructura predial determinada no garantizó un resultado en lo que se refiere a la adopción de una tecnología socialmente apropiada, así como que el funcionamiento predial y la estrategia de sobrevivencia de cada familia otorgaron al predio una dinámica propia, que muchas veces resultó determinante en el momento de adoptar la propuesta. Además, en la experiencia estudiada, no resultó suficiente diseñar la tecnología empleando recursos con control local ni presentar una única propuesta para la totalidad de los experimentadores. Los múltiples ajustes utilizados por los productores sugieren investigar los procesos de innovación local.In previous discussions about technological change, appropriate technologies emerged as one of the alternatives to the modernizing technology transfer model that prevailed for many years in Latin America. However, despite the time elapsed since its conceptual creation, it is not easy to find studies assessing interventions carried out with this type of approach. This paper addresses this subject by analyzing a technology transfer experience using goat manure as a fertilizer for household crops in Santiago del Estero (Argentina). Despite having an appropriate a priori design, the technology was not replicated by all the experimenters. A quantitative and qualitative two-stage approach was used to address it: the first approach explored structure variables used by each experimenter and correlated these with the times that he/she repeated the practice; and in the second one, an analysis of the farm operations through casestudies was carried out. The results indicate that a particular farm structure did not guarantee a result in terms of adoption of an appropriate technology,and that the operation and the survival strategy (or peasant strategy) of each family gave the farm an individual dynamic that often was decisive inadopting the proposal. In addition, at least for the current experience, technology design using locally controlled resources and the presentationof a unique proposal for all the experimenters was not enough. The multiple adjustments used by peasants suggest the need to investigate local innovation processes.Fil: Díaz, Juan Pablo. Universidad Nacional de Santiago del Estero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodriguez Sperat, Ramiro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Estudios para el Desarrollo Social. - Universidad Nacional de Santiago del Estero. Facultad de Humanidades Ciencias Sociales y de la Salud. Instituto de Estudios para el Desarrollo Social; ArgentinaFil: Paz, Raul Gustavo. Universidad Nacional de Santiago del Estero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Playing with your mind

A Brain-Computer Interface (BCI) is a communication system between the brainand a machine like a computer. Some BCI systems have been used to help people withdisabilities and sometimes, with entertainment purposes. In this paper, a BCI-game system is developed. It allows controlling the altitude of a ball inside of a glass pipe according to mental concentration level, which is measured on EEG signals of the user. The system is automatically adjusted to each user, hence, it is not needed any calibration step. Ten subjects participated in the experiments. They achieved effective control of the ball in a few minutes, demonstratingthe feasibility of the BCI-game system.Fil: Rodriguez, Mauro. Universidad Nacional de San Juan. Facultad de Ingeniería. Departamento de Electrónica y Automática. Gabinete de Tecnología Médica; ArgentinaFil: Gimenez, Ramiro. Universidad Nacional de San Juan. Facultad de Ingeniería. Departamento de Electrónica y Automática. Gabinete de Tecnología Médica; ArgentinaFil: Diez, Pablo Federico. Universidad Nacional de San Juan. Facultad de Ingeniería. Departamento de Electrónica y Automática. Gabinete de Tecnología Médica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Avila Perona, Enrique Mario. Universidad Nacional de San Juan. Facultad de Ingeniería. Departamento de Electrónica y Automática. Gabinete de Tecnología Médica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Laciar Leber, Eric. Universidad Nacional de San Juan. Facultad de Ingeniería. Departamento de Electrónica y Automática. Gabinete de Tecnología Médica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Orosco, Lorena Liliana. Universidad Nacional de San Juan. Facultad de Ingeniería. Departamento de Electrónica y Automática. Gabinete de Tecnología Médica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garces, Agustina. Universidad Nacional de San Juan. Facultad de Ingeniería. Departamento de Electrónica y Automática. Gabinete de Tecnología Médica; Argentin

One-pot synthesis of lignin-based electrospun oxygen reduction reaction electrocatalysts

Owing to their adequate combination of high surface area, electrical conductivity and electrochemical resistance, carbon fibers has been used for a long time as a catalyst supports and gas diffusion layers in the electrodes of fuel cells. However, the use of high amounts of noble metals in the cathode is hampering the commercial utilization of fuel cells. We have recently demonstrated that the electrospinning of lignin, a widely available and non-expensive biopolymer, allows the production of porous carbon cloths, which have been already utilized as electrodes for methanol oxidation and supercapacitors. In this work, we propose the electrospinning of lignin and noble/non-noble metal precursors for one-pot production of ORR catalysts. Fe, Co, Pd and Pt salts have been incorporated onto lignin-ethanol solutions and have been electrospun in microsized, metal-decorated lignin fibers. The stabilization and carbonization of these fibers have produced carbon electrodes with supported metallic nanoparticles up to 10 % wt. loading, avoiding the use of further impregnation steps. In addition, the incorporation of metal precursors in the lignin solution enhances the development of mesoporosity in the resulting carbon fibers, a desirable feature for increasing mass transfer rate when used as electrocatalyst, without compromising their electrical conductivity. The electrochemical characterization has confirmed that these carbon cloths are promising ORR catalysts that could be useful for the reducing the amount of noble metals in the electrodes or for allowing the use of non-noble metals as catalysts.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MINECO/FEDER CTQ2015-68654-R MINECO/FEDER CTQ2015-66080-R MINECO PTA2015-11464-

Incidencia de la aceleración de piso en el diseño de los elementos no estructurales en un edificio de 13 niveles estructurado con sistema DUAL

En el presente trabajo realizado se propuso determinar de la aceleración de piso mediante el análisis modal espectral de un edificio multifamiliar de trece pisos en los que se incluyó el cuarto de máquinas y la caja del ascensor el cual tiene como sistema resistente a cargas horizontales a un sistema dual, muy utilizado en el diseño de edificios en el Perú y otros países del mundo en donde se presentan actividad sísmica muy frecuente. El edificio ubicado en la calle Dean Saavedra 368- Trujillo. Con la finalidad de determinar las fuerzas que actúan sobre los elementos no estructurales, es decir los muros de tabiquería, y verificar cuales son los más vulnerables ante la acción sísmica Como primer desarrollo en el análisis estructural se efectuó un diseño mediante un modelo 3d, el mismo que fue sometido a cargas de gravedad y sismo, con la finalidad de obtener los valores de fuerza última requeridos para el diseño según las especificaciones de la norma peruana vigente de los elementos no estructurales, además de sustentar el diseño de cada uno de los elementos que forman parte de la edificación y poder estudiar la incidencia de la aceleración de piso en cada uno de ellos. Para el desarrollo de este proyecto se basó como base los anteriores estudios realizados a fin de poder tener un sustento tanto con los antecedentes como normativos en los cuales se emplearon las siguientes normas del Reglamento Nacional de Edificaciones . Norma E.020 Cargas. Norma E.030 Diseño sismorresistente 2016. Norma E.060 Concreto armado. Norma E.070 Albañileria.In the present work, the determination of the floor acceleration was proposed by means of the spectral modal analysis of a multifamily building of floors of the thirteen in which the machine room and the elevator box were included, which has as horizontal system a horizontal load A dual system, widely used in the design of buildings in Peru and other countries in the world where very frequent seismic activity occurs. The building located at Dean Street Saavedra 368- Trujillo. In order to determine the forces acting on the nonstructural elements, the walls of partition, and the verification of which are the most vulnerable to the seismic action As a first development in the structural analysis a design was carried out using a 3d model, the same one that was subjected to loads of gravity and earthquake, in order to obtain the values of the last force required for the design according to the specifications of the Peruvian standard of non-structural elements, besides supporting the design of each of the elements that are part of the building and the ability to study the incidence of acceleration of floor in each one of them. For the development of this project was based on the previous studies made in order to be able to have a support as much as the antecedents as normative in which the last norms of the National Building Regulations were used. Standard E.020 charges. Standard E.030 EQRD 2016. Standard E.060 reinforced concrete. Standard E.070 masonry.Tesi