La máquina de escribir : Manual de producción de textos. Libros I y II. Colección Libros de Cátedra, Edulp

Los profesores del Liceo “Víctor Mercante” sabemos que escribir es una tarea habitual para nuestros alumnos. Ellos son nuestros primeros destinatarios. Y lo son por cuestiones pragmáticas: a diario se les solicita que resuelvan consignas de evaluaciones, que brinden definiciones, realicen resúmenes, produzcan relatos de ficción, presenten cartas, formulen reseñas e informes. Se trata de prácticas que dan cuenta de un trabajo intelectual cuya complejidad va in crescendo conforme avanza su formación y que, aún en los primeros años del Ciclo Básico, supone pensar en un destinatario, analizar lo que otros han dicho sobre un tema, establecer relaciones lógicas y semánticas en el interior del propio texto y entre textos diversos y, en paralelo, constituirse en un observador agudo y analítico que pueda tomar distancia de posturas personales, considerar el tema dentro de un marco o sistema conceptual más amplio y fundamentar sus aserciones. Ahora bien, ¿tenemos siempre la certeza de que los alumnos conocen los alcances de estos verbos? ¿Cuánto saben nuestros estudiantes de las particularidades genéricas de los textos de circulación escolar? ¿Cuánto tiempo dedicamos los docentes –de las diversas disciplinas– a la alfabetización en la especificidad de los géneros escolares? Suele ocurrir que, si bien somos conscientes de que la alfabetización en las formas de la escritura académica escolar es un objetivo didáctico central de la escuela secundaria, los profesores damos por sentado que los estudiantes conocen cuáles son las particularidades de los géneros escolares que les solicitamos a diario. Los autores de La máquina de escribir. Manual de producción de textos intentamos desandar el camino al que conduce ese presupuesto ya que consideramos que la escritura no es una experiencia natural sino que es el resultado de prácticas sistemáticas, continuas y complejas que requieren de una instrucción adecuada llevada a cabo en las escuelas que son, ni más ni menos, las instituciones pensadas para tal fin.Liceo "Víctor Mercante

The Third Fermi Large Area Telescope Catalog of Gamma-ray Pulsars

We present 294 pulsars found in GeV data from the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. Another 33 millisecond pulsars (MSPs) discovered in deep radio searches of LAT sources will likely reveal pulsations once phase-connected rotation ephemerides are achieved. A further dozen optical and/or X-ray binary systems co-located with LAT sources also likely harbor gamma-ray MSPs. This catalog thus reports roughly 340 gamma-ray pulsars and candidates, 10% of all known pulsars, compared to $\leq 11$ known before Fermi. Half of the gamma-ray pulsars are young. Of these, the half that are undetected in radio have a broader Galactic latitude distribution than the young radio-loud pulsars. The others are MSPs, with 6 undetected in radio. Overall, >235 are bright enough above 50 MeV to fit the pulse profile, the energy spectrum, or both. For the common two-peaked profiles, the gamma-ray peak closest to the magnetic pole crossing generally has a softer spectrum. The spectral energy distributions tend to narrow as the spindown power $\dot E$ decreases to its observed minimum near $10^{33}$ erg s$^{-1}$, approaching the shape for synchrotron radiation from monoenergetic electrons. We calculate gamma-ray luminosities when distances are available. Our all-sky gamma-ray sensitivity map is useful for population syntheses. The electronic catalog version provides gamma-ray pulsar ephemerides, properties and fit results to guide and be compared with modeling results.Comment: 142 pages. Accepted by the Astrophysical Journal Supplemen

Copernicus Ocean State Report, issue 6

The 6th issue of the Copernicus OSR incorporates a large range of topics for the blue, white and green ocean for all European regional seas, and the global ocean over 1993–2020 with a special focus on 2020

Structural characterization of protein isolates obtained from chia (Salvia hispanica L.) seeds

Chia protein isolates (CPI) were obtained through isoelectric precipitation under two different conditions in order to compare their structural properties. Extraction was carried out at pH 10 or 12, whereas precipitation pH was fixed at 4.5. Samples were named as CPI10 or CPI12, according to their extraction pH (10 or 12, respectively). The recovery of chia proteins was higher when the extraction was carried out at pH 12 (17% for CPI12 and 13% for CPI10); however, CPI12 protein content (775g/kg) was slightly lower than CPI10 protein content (782g/kg). Both samples showed similar SDS-PAGE pattern. Protein dispersions of both isolates led to highly stabilized particles due to their negative ζ potential (around -54 mV). CPI10 has a higher proportion of small particles in suspension, revealed by a lower d3,2 value. Spectroscopic techniques showed that CPI10 presented higher content of β-helix than CPI12, resulting in higher thermal stability. This observation was supported by FT-IR spectroscopy since CPI10 presented less unordered structure than CPI12. The energy of endotherms obtained in CPI12 was considerably lower than in CPI10. Extraction at higher alkaline conditions led to a more denatured protein conformation with a higher content of random structure (18.1% for CPI10 and 22.9% for CPI12).Fil: López, Débora Natalia. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Fisicoquímica; Argentina.Fil: López, Débora Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Ingrassia, Romina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Fisicoquímica; Argentina.Fil: Ingrassia, Romina. Universidad Nacional de Rosario. Facultad de Ciencias Veterinarias; Argentina.Fil: Busti, Pablo Andrés. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Tecnología de los Alimentos; Argentina.Fil: Julia, Bonino. Pontificia Universidad Católica Argentina. Facultad de Química e Ingeniería del Rosario; Argentina.Fil: Delgado, Juan Francisco. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina.Fil: Delgado, Juan Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Wagner, Jorge Ricardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina.Fil: Wagner, Jorge Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Boeris, Valeria. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Fisicoquímica; Argentina.Fil: Boeris, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Boeris, Valeria. Pontificia Universidad Católica Argentina. Facultad de Química e Ingeniería del Rosario; Argentina.Fil: Spelzini, Darío. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Fisicoquímica; Argentina.Fil: Spelzini, Darío. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Spelzini, Darío. Pontificia Universidad Católica Argentina. Facultad de Química e Ingeniería del Rosario; Argentina

The residue 179 is involved in product specificity of the Bacillus circulans DF 9R cyclodextrin glycosyltransferase

Cyclodextrin glycosyltransferases (CGTases) are important enzymes in biotechnology because of their ability to produce cyclodextrin (CD) mixtures from starch whose relative composition depends on enzyme source. A multiple alignment of 46 CGTases and Shannon entropy analysis allowed us to find differences and similarities that could be related to product specificity. Interestingly, position 179 has Gly in all the CGTases except in that from Bacillus circulans DF 9R which possesses Gln. The absence of a side chain at that position has been considered as a strong requirement for substrate binding and cyclization process. Therefore, we constructed two mutants of this enzyme, Q179L and Q179G. The activity and kinetic parameters of Q179G remained unchanged while the Q179L mutant showed a different CDs ratio, a lower catalytic efficiency, and a decreased ability to convert starch into CDs. We show that position 179 is involved in CGTase product specificity and must be occupied by Gly—without a side chain—or by amino acid residues able to interact with the substrate through hydrogen bonds in a way that the cyclization process occurs efficiently. These findings are also explained on the basis of a structural model.Universidad Nacional de Luján; Universidad de Buenos Aires; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Peer reviewe

The residue 179 is involved in product specificity of the Bacillus circulans DF 9R cyclodextrin glycosyltransferase

Cyclodextrin glycosyltransferases (CGTases) are important enzymes in biotechnology because of their ability to produce cyclodextrin (CD) mixtures from starch whose relative composition depends on enzyme source. A multiple alignment of 46 CGTases and Shannon entropy analysis allowed us to find differences and similarities that could be related to product specificity. Interestingly, position 179 has Gly in all the CGTases except in that from Bacillus circulans DF 9R which possesses Gln. The absence of a side chain at that position has been considered as a strong requirement for substrate binding and cyclization process. Therefore, we constructed two mutants of this enzyme, Q179L and Q179G. The activity and kinetic parameters of Q179G remained unchanged while the Q179L mutant showed a different CDs ratio, a lower catalytic efficiency, and a decreased ability to convert starch into CDs. We show that position 179 is involved in CGTase product specificity and must be occupied by Gly—without a side chain—or by amino acid residues able to interact with the substrate through hydrogen bonds in a way that the cyclization process occurs efficiently. These findings are also explained on the basis of a structural model.This work was supported by grants from the Universidad Nacional de Luján, Universidad de Buenos Aires, and the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). AJD, CMB, and MBJB are career members of CONICET.Peer reviewe

Synthesis of Monoglycerides by Esterification of Oleic Acid with Glycerol in Heterogeneous Catalytic Process Using Tin-Organic Framework Catalyst

Selective synthesis of monoglycerides by esterification of glycerol with fatty acids is a difficult reaction because of immiscibility of reagents and the formation of di- and tri-glyceride by-products. In this work a heterogeneous catalytic process was conceived in which the reactant mixture was homogenized using tert-butanol solvent. Candidate catalysts were screened in the reaction of oleic acid with glycerol. While under such reaction conditions zeolites were rather inactive, metal-organic frameworks and, especially, tin-organic frameworks were found promising. A tin-organic framework (Sn-EOF) was most active and achieved ≥98 % monoglyceride selectivity at 40 % conversion in catalyzing esterification of oleic acid with glycerol at a low reaction temperature of 150 C. Leaching of tin from Sn-EOF catalyst was suppressed by limiting the amount of oleic acid in the starting mixture. Characterization of the acid sites of Sn-EOF by pyridine-chemisorption and FTIR revealed Lewis acidity to be responsible for the catalytic activity. © 2013 Springer Science+Business Media New York.status: publishe

Synthesis of Monoglycerides by Esterification of Oleic Acid with Glycerol in Heterogeneous Catalytic Process Using Tin-Organic Framework Catalyst

INGENIERIE+TLE:DFASelective synthesis of monoglycerides by esterification of glycerol with fatty acids is a difficult reaction because of immiscibility of reagents and the formation of di- and tri-glyceride by-products. In this work a heterogeneous catalytic process was conceived in which the reactant mixture was homogenized using tert-butanol solvent. Candidate catalysts were screened in the reaction of oleic acid with glycerol. While under such reaction conditions zeolites were rather inactive, metal-organic frameworks and, especially, tin-organic frameworks were found promising. A tin-organic framework (Sn-EOF) was most active and achieved a parts per thousand yen98 % monoglyceride selectivity at 40 % conversion in catalyzing esterification of oleic acid with glycerol at a low reaction temperature of 150 A degrees C. Leaching of tin from Sn-EOF catalyst was suppressed by limiting the amount of oleic acid in the starting mixture. Characterization of the acid sites of Sn-EOF by pyridine-chemisorption and FTIR revealed Lewis acidity to be responsible for the catalytic activity

Caracterización fisicoquímica de aislados de proteínas vegetales

Resumen: Las proteínas vegetales constituyen una fuente de nutrientes e ingredientes funcionales de interés y presentan amplia versatilidad en cuanto a sus características fisicoquímicas. La quinua y la chía han sido reconocidas debido a su alto contenido de proteínas y su apropiado balance de aminoácidos. Se prepararon aislados de proteínas de quinua y de chía por extracción alcalina seguida de precipitación en medio levemente ácido. Se optimizaron las condiciones de obtención de los aislados: la relación materia prima/solvente, el pH de extracción y el pH de precipitación. Se determinó el contenido de estructura secundaria de las proteínas y el potencial de los aislados proteicos en suspensión. Se estudió el proceso de agregación ácida de las proteínas vegetales estudiadas mediante turbidimetría. Se determinó la capacidad del aislado de proteína de quinua de inhibir parcialmente el pardeamiento enzimático en banana.Abstract: Vegetable proteins have wide versatility in their physico-chemical characteristics and constitute an interesting source of nutrients and functional ingredients. Quinoa and chia have been recognized because of their high protein content and their appropriate amino acid balance. Quinoa and chia protein isolates were prepared by alkaline extraction followed by precipitation in mild acid medium. Conditions of isolates obtainment were optimized: raw material / solvent ratio, pH of extraction and pH of precipitation. Secondary structure content of the proteins and - potential of the protein isolates in suspension were determined. Acid aggregation process of these proteins was studied by turbidimetry. Ability of the quinoa protein isolate to partially inhibit enzymatic browning in banana was determined