Simulation of an Industrial Packed Column for Reactive Absorption of CO2 Gómez, C.; Borio, Daniel Oscar; Schbib, Noemi Susana − The steady-state simulation of a reactive absorption column is presented. The absorber is used in a large-scale ammonia plant to remove CO2 from the process gas stream. To enhance the absorption process, high pressures and low temperatures are commonly used (T = 45-80 °C, P = 30-40 bar). At the outlet of the absorber, the CO2 content in the process gas must be reduced to less than 500 ppm (dry basis) to avoid an excessive temperature rise in the methanation reactor (downstream of the absorption section). To represent the gas-liquid system, a rigorous mathematical model based on the two-film theory is considered. The heat effects are taken into account. The behaviour of different process variables for a reference operating condition is analyzed. The influence of changes in some operating variables is evaluated.

On-line complexation/cloud point preconcentration for the sensitive determination of dysprosium in urine by flow injection inductively coupled plasma-optical emission spectrometry Ortega, Claudia Alicia; Cerutti, Estela Soledad; Olsina, Roberto Antonio; Silva, María Fernanda; Martinez, Luis Dante An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with ICP-OES was studied. For the preconcentration of dysprosium, a Dy(III)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex was formed on-line at pH 9.22 in the presence of nonionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 30°C in order to promote phase separation, and the surfactant-rich phase was retained in a microcolumn packed with cotton at pH 9.2. The surfactant-rich phase was eluted with 4 mol L-1 nitric acid at a flow rate of 1.5 mL min -1, directly in the nebulizer of the plasma. An enhancement factor of 50 was obtained for the preconcentration of 50 mL of sample solution. The detection limit value for the preconcentration of 50 mL of aqueous solution of Dy was 0.03 μg L-1. The precision for 10 replicate determinations at the 2.0 μg L-1 Dy level was 2.2% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for dysprosium was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 μg L-1. The method was successfully applied to the determination of dysprosium in urine.

Cohomology of split algebras and of trivial extensions Cibils, Claude; Marcos, Eduardo; Redondo, Maria Julia; Solotar, Andrea Leonor We consider associative algebras λ over a field provided with a direct sum decomposition of a two-sided ideal M and a sub-algebra A - examples are provided by trivial extensions or triangular type matrix algebras. In this relative and split setting we describe a long exact sequence computing the Hochschild cohomology of λ. We study the connecting homomorphism using the cup-product and we infer several results, in particular the first Hochschild cohomology group of a trivial extension never vanishes.

Report on the 1st International Workshop of the IUGS Lower Cretaceous Ammonite Working Group, the 'Kilian Group' (Lyon, 11 July 2002) Hoedemaeker, Philip J.; Reboulet, Stéphane; Aguirre-Urreta, Maria Beatriz; Alsen, Peter; Aoutem, Mohamed; Atrops, François; Barragan, Ricardo; González Arreola, Celestina; Klein, Jaap; Lukeneder, Alexander; Ploch, Isabela; Raisossadat, Seyed Naser; Rawson, Peter F.; Ropolo, Pierre; Vasícek, Zdenek; Vermeulen, Jean; Wippich, Max G. E. The Lower Cretaceous Ammonite Working Group forms part of the IUGS Subcommission on Cretaceous Stratigraphy (Peter Rawson, chair) and is the successor of the Lower Cretaceous Cephalopod Team that formed part of IGCP Projects 262 and 362 respectively. The latter team had organized five Workshops (Klein & Hoedemaeker, 1999;Hoedemaeker & Rawson, 2000) and this is the first workshop under the new IUGS umbrella, which was organized by Stéphane Reboulet (Université de Lyon 1) directly after the 3rd French Symposium on Stratigraphy (Lyon, 8–10 July 2002). The workshop was attended by 18 members from 13 countries. The attendants agreed to call the group the ‘Kilian Group' after the famous French palaeontologist W. Kilian.

A prothrombin activator from Bothrops erythromelas (jararaca-da-seca) snake venom: characterization and molecular cloning Silva, Márcia B.; Schattner, Mirta Ana; Ramos, Celso R. R.; Junqueira de Azevedo, Inácio L. M.; Guarnieri, Míriam C.; Lazzari, María Ángela; Sampaio, Claudio A. M.; Pozner, Roberto Gabriel; Ventura, Janaina S.; Ho, Paulo L.; Chudzinski Tavassi, Ana M. A novel prothrombin activator enzyme, which we have named 'berythractivase', was isolated from Bothrops erythromelas (jararaca-da-seca) snake venom. Berythractivase was purified by a single cation-exchange-chromatography step on a Resource S (Amersham Biosciences) column. The overall purification (31-fold) indicates that berythractivase comprises about 5% of the crude venom. It is a single-chain protein with a molecular mass of 78 kDa. SDS/PAGE of prothrombin after activation by berythractivase showed fragment patterns similar to those generated by group A prothrombin activators, which convert prothrombin into meizothrombin, independent of the prothrombinase complex. Chelating agents, such as EDTA and o-phenanthroline, rapidly inhibited the enzymic activity of berythractivase, like a typical metalloproteinase. Human fibrinogen Aα-chain was slowly digested only after longer incubation with berythractivase, and no effect on the β- or γ-chains was observed. Berythractivase was also capable of triggering endothelial proinfiammatory and procoagulant cell responses, von Willebrand factor was released, and the surface expression of both intracellular adhesion molecule-1 and E-selectin was up-regulated by berythractivase in cultured human umbilical-vein endothelial cells. The complete berythractivase cDNA was cloned from a B. erythromelas venom-gland cDNA library. The cDNA sequence possesses 2330 bp and encodes a preproprotein with significant sequence similarity to many other mature metalloproteinases reported from snake venoms. Berythractivase contains metalloproteinase, desintegrin-like and cysteine-rich domains. However, berythractivase did not elicit any haemorrhagic response. These results show that, although the primary structure of berythractivase is related to that of snake-venom haemorrhagic metalloproteinases and functionally similar to group A prothrombin activators, it is a prothrombin activator devoid of haemorrhagic activity. This is a feature not observed for most of the snake venom metalloproteinases, including the group A prothrombin activators.

Propagator matrices as matrices of power's series. II. It's relationship with HF's stability problem and alternative solutions Gómez, Carlos Anselmo; Provasi, Patricio Federico; Aucar, Gustavo Adolfo Some non-singlet quasi-instabilities (QIs) cases that arise in the calculation of NMR-Jparameters are analyzed within response theory. The relationship between ‘very close to zero’ eigenvalues of the principal propagator and the rate of convergency for specific coupling pathways is shown by a power series implemented to calculate the principal propagator matrix. A natural criterion for the analysis of the stability problem emerges from that series. This is more general and accurate compared with previous proposals. Its relationship with π-type molecular orbitals is given. We present an alternative scheme to minimize the effects of non-singlet QIs in such a way that the NMR-J parameters become close to the best theoretical calculations for H2CX (X=CH2, NH and O).

Arginine metabolic pathways involved in the modulation of tumor‐induced angiogenesis by macrophages Davel, Lilia Elena; Jasnis, Maria Adela; de la Torre, Eulalia; Gotoh, Tomomi; Diament, Miriam; Magenta, Gabriela Viviana; Sacerdote de Lustig, Eugenia; Sales, María Elena Neovascularization, an essential step for tumor progression and metastasis development, can be modulated by the presence of macrophages (Mps) in the tumor microenvironment. The ability of Mps to regulate the angiogenicity of the LMM3 tumor cell line was studied. Peritoneal Mps from LMM3 tumor‐bearing mice (TMps) potentiate in vivo LMM3 angiogenicity. These results were confirmed by CD31 immunoblotting assays. The activity of TMps depended on nitric oxide synthase (NOS) and arginase (A) activity. By immunoblotting we evidenced that AI and AII isoforms were up‐regulated in TMps while the inducible and neuronal NOS isoforms were highly expressed in normal Mps. TMps might positively modulate tumor growth by stimulating angiogenic cascade mainly through polyamine synthesis.

Body mass and habitat correlates of song structure in a primitive group of birds Bertelli, Sara Beatriz; Tubaro, Pablo Luis We assessed relationships between acoustic frequency, body mass, and habitat in tinamous. This monophyletic group of primitive birds comprises 47 ground dwelling species whose habitats range from dense humid forest to open grasslands.The relationship between frequency and body mass was found to be negative, while the songs of open habitat species exhibited higher frequencies and a wider bandwidth than the closed-habitat ones. Residual variation in song frequency, after controlling for the effect of body mass and phylogeny, tends to differ among habitats. However, a statistical test of this pattern was not possible because of the existence of only five pairs of sister species differing in habitat. In spite of this, positive contrasts of bandwidth were associated with positive contrasts of habitat, confirming that songs of open-habitat species have a wider bandwidth than those of their more closed habitat relatives.

How reliable could economic Hartree-Fock computations be in studying large, folded peptides? A comparative HF and DFT case study on N- and C-protected aspartic acid Koo, Joseph C.P.; Lam, Janice S.W.; Salpietro, Salvatore J.; Chass, Gregory A.; Enriz, Ricardo Daniel; Torday, Ladislaus L.; Varro, Andras; Papp, Julius Gy. In this study, potential energy hypersurfaces have been generated and analyzed for each of the nine possible backbone (BB) conformations for both the endo and exo forms of N-acetyl-L-aspartic acid N′-methylamide. Ab initio calculations were carried out at RHF/3-21G, RHF/6-31G(d), and B3LYP/6-31G(d) levels for all backbone conformations. The relative energies, as well as stabilization energies exerted by the sidechain (SC) on the backbone, were calculated for all stable conformers. All sidechain-sidechain (HO···O=C), backbone-backbone (N-H⋯O=C), and sidechain-backbone (N-H···O=C; N-H···OH) hydrogen bond interactions were analyzed. The appearance of the traditionally absent αL and εL conformers may be recognized as special geometric orientation which the aspartyl residue manifests during peptide folding or ligand docking in a receptor that contains aspartic acids in its ligand recognition sites. At all three levels of theory, there exists a trend between the hydrogen bond distance and ring size. In addition, strikingly high correlations between the torsional angles (R2 = 0.9937 for RHF/6-31G(d) versus RHF/3-21G; R2 = 0.9967 for B3LYP/6-31G(d) versus RHF/6-31G(d); R2 = 0.9914 for B3LYP/6-31G(d) versus RHF/3-21G) and between the ΔE values in kcal/mol (R2 = 0.9424 for RHF/6-31G(d) versus RHF/3-21G; R2 = 0.9108 for B3LYP/6-31G(d) versus RHF/6-31G(d); R2 = 0.9434 B3LYP/6-31G(d) versus RHF/3-21G) found at the different ab initio levels suggest that calculations carried out at the lower levels (i.e. at RHF/3-21G) are still significant.

Orobothriurus atiquipa, a new bothriurid species (Scorpiones) from Lomas in southern Perú Ochoa, José Antonio; Acosta, Luis Eduardo Orobothriurus atiquipa new species (Scorpiones, Bothriuridae) from Lomas formations in the coastal desert of southern Perú is described and illustrated. This species belongs to the alticola species-group, and within the group, it is closely related to O. alticola (Pocock), O. paessleri (Kraepelin) and O. curvidigitus (Kraepelin). The spine formula (4 + 3) on tarsi III–IV is probably an autapomorphy for the new species. Some features of the habitat (the Lomas formation are green isolates in the coastal desert), as well as a distribution map are provided.

Papel del calcio y de la vitamina D en la salud ósea (Parte I) Sánchez, A.; Puche, R.; Zeni, Susana Noemi; Oliveri, María Beatriz; Galich, Ana María; Maffei, L.; Plantalech, L; Poudes, G.; Bregni, Carlos La osteoporosis, definida como una baja masa ósea y alteraciones de la microarquitectura del hueso que predisponen a las fracturas, es una enfermedad que asume características de pandemia y cuya prevalencia crecerá notoriamente en las próximas décadas en todo el mundo, pero sobre todo en Asia y América Latina. Si bien el desarrollo y el mantenimiento de una masa ósea normal dependen en un 70% de factores genéticos, los factores ambientales (como el ejercicio y la nutrición) son de gran importancia, y pueden modificarse favorablemente a nivel poblacional con apropiadas medidas educativas y culturales. Esta revisión se propone pasar revista al metabolismo del calcio y presentar la evidencia disponible sobre el papel que este nutriente (y la vitamina D, crucial para su correcta disponibilidad) tiene en el desarrollo y mantenimiento de un esqueleto sano; sobre la importancia fisiopatológica de la carencia crónica de calcio en el desarrollo de osteopenia en niños, jóvenes, adultos y viejos; y sobre el efecto beneficioso de la suplementación con calcio (y, a veces, de vitamina D) en la prevención y el tratamiento de la osteoporosis.

Una metáfora del vínculo vasallático: El Libro del Buen Amor Rígano, Mariela Elizabeth El objetivo de este trabajo es analizar el desarrollo metafórico de la relación vasallo-señor en el Libro del Buen Amor. El texto presenta, bajo la apariencia de este vínculo, a) la relación entre los seres humanos y la divinidad, sea esta pagana o cristiana, b) entre diversos animales entre sí y, finalmente, c) entre la personificación de costumbres cristianas (Carnal y Cuaresma) y distintos animales. Consideramos, entonces, que puede resultar particularmente interesante un estudio sobre el empleo de los elementos lingüísticos y paralingüísticos como recurso para caracterizar a los diferentes personajes y sus relaciones jerárquicas, puesto que podría ser un indicador de la difusión que este sistema habría alcanzado en ese momento histórico.Este trabajo se enmarca dentro de los lineamientos de la sociolingüística histórica.; The objective of this paper is to analyse the terms of address, the lexicon and the paralinguistic elements that are used in the Libro del Buen Amor (XIV c.) to present metaphorical the tie between beings of different hierarchy like the relationship between a vassal and a lord. This type of metaphors could be a indicator of the diffusion of the courtesy system in this century.

Stylized Facts of the Gross National Product of Argentina: 1875 - 1999 Abril, Juan Carlos; Blanco, Maria Beatriz The stylized facts of macroeconomic time series can be presented by fitting structural time series models. Within this framework, we study the behaviour of the gross national product of Argentina in the long run and provide a method for modelling this behaviour, which in turn is equivalent to establishing the stylized facts associated with these time series. We analyse the annual data of the gross national product and the gross national product per capita of Argentina from 1875 to 1999. The study of these variables allows, among other things, to know the changes that have been taking place in the economy. The evolution of these variables in time tells us, roughly, if there was progress or not.

Foraging grounds of southern giant petrels (Macronectes giganteus) on the Patagonian shelf Quintana, Flavio Roberto; Dell'arciprete, Olga Patricia During the 1999 and 2000 breeding seasons we used satellite telemetry to track the foraging movements of four southern giant petrels (Macronectes giganteus) nesting on an island off the Argentine coast (45°08′, 66°03′). Three of the four individuals foraged east/southeast of the colony, over the middle continental shelf and the shelf break, between 43° and 51°S. The fourth individual remained in coastal areas to the south and lost the device after 15.5 days at sea. The maximum linear distance from the nest reached during a single foraging trip was 552 km. All birds were able to fly more than 400 km in 1 day, with a maximum of 513 km recorded. The maximum total distance covered in a single foraging trip was 2,540 km. Findings of this study emphasise the importance of the Patagonian continental shelf as foraging grounds for top predators in the South Atlantic Ocean.

Nucleotide sequence of the upstream regulatory region of BoLA-DRB Ripoli, María Verónica; Diaz, Silvina; Peral Garcia, Pilar; Giovambattista, Guillermo The sequence of the proximal upstream regulatory region (URR) of the bovine DRB genes was amplified using oligonucleotide primers designed from the consensus among DRB sequences from different species. The obtained DNA sequence was 234 bp long and composed of highly conserved sequence motifs, showing the same organization as the HLA-DRB, H2-IAb, H2-IEb and ELA-DRB genes. In this paper we report the sequence of the proximal upstream regulatory region (URR) of the bovine DRB genes. These are the first sequence data on the upstream regulatory regions of MHC class II genes in cattle. The reverse oligonucleotide primer (5′-GAGAAATA-CAGACACACCATGC-3′) was designed from the consensus among DRB sequences from different species: BoLA-DRB (accession numbers U77067-68, U78548 and D45357), SLA-DRB (M55165-6), HLA-DRB (S72812 and L07838-40), H2-IEb and H2-IAb (X86151-6). As a forward primer we used the oligonucleotide proposed by Turco et al. (1990) (5′-TGTTTCAGAAAAGGACCTTC-3′), which was designed from the consensus among HLA-DRB sequences corresponding to the promoter region of the DRB genes. A polymerase chain reaction (PCR) was carried out in a total volume of 25 μl comprising 2.5 mM MgCl2 Tris-HCl (pH = 8.4), 50 mM KCl, 100 μM of each dNTP, 0.5 μM of each primer, 1.0 unit Taq polymerase (Gibco BRL, Life-Technologies, Grand Island, NY) and 50-100 ng DNA template. The genomic DNA was extracted from whole blood from one animal of the Saavedreño Creole breed. The amplification profile consisted of 1 min at 94°C, followed by 30 cycles of 45 s at 94°C, 45 s at 55°C and 45 s at 72°C, with a final extension of 3 min at 72°C. The amplification products were cloned into a dT-tailed pGEM-T easy vector (Promega, Madison, WI), and three clones of each PCR product were sequenced on an Applied Biosystems 377 automated sequencer (Bio-Resource Center, Cornell University, Ithaca, NY), using a T7 universal primer. All the sequenced clones exhibited 100% sequence similarity to each other. The nucleotide sequence of the proximal upstream control region of the BoLA-DRB genes (GenBank accession number AY040327) was 234 bp long and composed of highly conserved sequence motifs that included, from the 5′ to the 3′ direction, W, X, Y, CCAAT and TATA-like boxes (Fig. 1), showing the same organization of the conserved regulatory elements as the HLA-DRB, H2-IAb, H2-IEb and ELA-DRB genes (e.g. Louis et al., 1993, 1994; Singal et al., 1993; Singal & Qiu, 1994). Furthermore, the BoLA-DRB URR nucleotide sequence had higher identity with HLA-DRB sequences than with HLA-DQB sequences (data not shown). This suggests that the sequence AY040327 corresponds to a BoLA-DRB promoter. However, we are still unable to assign this sequence to a specific BoLA-DRB gene, as at least three BoLA-DRB genes have been reported to exist (Andersson et al., 1986; Muggli-Cocket & Stone, 1988). BoLA-DRB3 is the most expressed DRB gene in cattle, while DRB1 is expressed at a low level and DRB2 is a pseudogene (Burke et al., 1991).

The Crassispora kosankei-Cystoptychus azcuyi palynozone of the Upper Carboniferous Tupambi Formation, Tarija Basin, northern Argentina Di Pasquo Lartigue, Maria Well-preserved and diverse palynomorph assemblages were recovered from surface and core samples from the middle to upper section of the Tupambi Formation. The latter is the basal unit of the Machareti Group (Upper Carboniferous) of the Tarija Basin, northern Argentina. Assemblages are composed of trilete miospores, one hilate species, monosaccate pollen grains (one species striated), one praecolpate species and green algae (Botryococcus). Two key species are Cystoptychus azcuyi sp. nov. and Crassispora kosankei (Potonié and Kremp) Bharadwaj emend. Smith and Butterworth enable definition of the first palynozone for this basin. The age, as well as the biostratigraphic and paleogeographic significance of the palynoflora is discussed.

Palynological zonation of the Lajas Formation (Middle Jurassic) of the Neuquén Basin, Argentina; Zonación palonológica de la Formación Lajas (Jurásico Medio), Cuenca Neuquina Martinez, Marcelo Adrian En este trabajo es presentada una nueva zonación palinológica para el Jurásico Medio del sector sur de la Cuenca Neuquina, con dos zonas y ocho subzonas creadas en base a esporomorfos y microplanton asociado, con un rango de edad que abarca desde el Aaleniano tardío hasta el Caloviano temprano. La zonación es correlacionada con zonaciones palinológicas previas de la mencionada cuenca. Se menciona el contenido macropaleontológico (principalmente amonites) y micropaleontológico (frecuencias relativas de taxones y grupos supragenéricos); A new palynological zonation for the Middle Jurassic of the southern part of the Neuquén Basin is presented. Two zones and eight subzones based on sporomorphs and associated microplankton of late Aalenian to early Callovian age are defined. These zones are correlated with previous palynological zonations in the Neuquén Basin. The macropaleontologic (mainly ammonites) and micropaleontologic content (relative frequencies of taxa and suprageneric groups) of each depositional sequence previously identified in the study area by other workers are given

Estimation of the plain high-cycle fatigue propagation resistance in steels Chapetti, Mirco Daniel In this work a method to estimate the high cyclic fatigue propagation life of steel specimens under constant loading is presented. This method is based in experimental evidence that the fatigue limit represents the threshold stress for the propagation of nucleated cracks, so that both the fatigue limit and the fatigue resistance depend on the effective resistance of the microstructural barriers that have to be overcome by the nucleated cracks. It is proposed also, that in those cases where the number of cycles that is necessary for the nucleation of the cracks can be neglected, the fatigue crack propagation life can be taken as an estimation of the total fatigue life. The high cycle fatigue propagation life of a structural steel of the type JIS 10C is estimated.

Brief commentary Schattner, Mirta Ana; Lazzari, María Ángela Recently, Tibbles et al. [1] reported that thrombopoietin (TPO) was capable of inducing P-selectin expression independently of calcium movements or platelet aggregation. They also found that leukocyte– platelet aggregates occurred after TPO cell stimulation most probably mediated by P-selection expression. Although they stated that they described a novel role for TPO in platelet function and platelet–leukocyte interactions both activities have been previously described by severalgroups [2–6]. Most of the studies showed that although TPO was not able to induce platelet activation alone it synergized platelet responses, including P-selectin expression, triggered by different agonists.

Reforma a la gestión educativa e identidad profesional de los docentes en Argentina: Estudio de un caso; Educational management reform and professional teacher identity in Argentina: A case study Freytes Frey, Ada Cora Dentro de la reforma educativa argentina, el 3° ciclo de la Educación General Básica (EGB) constituye un aspecto central, ya que plantea importantes quiebres con respecto a la estructura anterior. Este ciclo está integrado por los antiguos 7° grado de la escuela primaria y 1° y 2° año de la secundaria, por lo que implica la convivencia de dos culturas profesionales diferentes: la de los maestros y la de los profesores. A esto se suma la reformulación del rol docente que impulsa la reforma. En este trabajo, se analiza la incidencia de estos procesos en la constitución de la identidad profesional de los docentes del 3° ciclo en la provincia de Buenos Aires. Esto supone una indagación en diversos planos: a) las interpelaciones acerca de la identidad docente presentes en los discursos y lineamientos acerca de la implementación del 3º ciclo de la EGB en dicha provincia; b) los significados y representaciones identitarias que se van constituyendo en las interacciones cotidianas en las escuelas; c) las maneras en que son recibidas y procesadas estas interpelaciones y representaciones por los docentes del 3º ciclo, en un trabajo interpretativo que supone también resistencias y reformulaciones. Este planteo supone un contrapunto entre lo macro -abordado a través del análisis de contenido de ciertos discursos públicos- y lo micro -examinado a través de un estudio de casos múltiples en diversas escuelas bonaerenses-.; Within Argentine educational reform, the 3rd stage of General Basic Education (EGB) is a central aspect, since it involves important differences with regard to the former educative system structure. This stage is composed by the former primary school 7th grade and secondary school 1st and 2nd year. Therefore, it involves the daily interaction of two distinct professional cultures: that of primary and secondary school teachers. In addition, the reform policy promotes a redefinition of teachers’ roles. The paper analyses the impact of this process on the construction of 3rd stage teachers’ professional identity in the Argentine Buenos Aires province. It encompasses different levels of research: a) the interpellations about teaches’ identity found in discourses and political measures regarding the 3rd stage implementation; b) the meanings and representations as to identity constructed during daily interactions in schools; c) the diverse ways these interpellations and representations are received, interpreted and processed by 3rd stage teachers. This approach attempts to explore the macro level through content analysis of public discourses and the micro level through a multiple case study in schools. It also attempts to relate both levels.