Physicochemical, Water Vapor Barrier and Mechanical Properties of Corn Starch and Chitosan Composite Films Garcia, Maria Alejandra; Pinotti, Adriana Noemi; Zaritzky, Noemi Elisabet Biodegradable flexible films were developed from corn starch (CS) and chitosan (CH); their microstructure, mechanical and barrier properties were evaluated. Chitosan and starch blend filmogenic suspensions showed a pseudoplastic behavior, similar to that of chitosan solutions. Smooth surfaces, homogeneous and compact film structures were observed from microstructure studies using scanning electron microscopy (SEM). The addition of glycerol reduced film opacity and increased film solubility of both CS and composite CS‐CH films. Water vapor permeability values of composite CS‐CH films plasticized with glycerol ranged between 3.76 and 4.54× 10−11 g s−1 m−1 Pa−1, lower than those of the single component films. CS‐CH films were resistant and their flexibility increased with glycerol addition. Tensile strength values of CS‐CH films were comparable to those of low‐density and high‐density polyethylenes but lower than that obtained for cellophane, however, composite biodegradable films showed lower elongation at break values than the synthetic commercial ones. In conclusion, CS‐CH films can be described as biofilms with a homogeneous matrix, stable structure and interesting water barrier and mechanical properties, with great possibilities of utilization, and with the advantage of biodegradability.

Shooting control in Eucalyptus Grandis x E. urophylla hybrid: Comparative effects of 28-homocastasterone and a 5α-monofluoro derivative Pereira Netto, Adaucto B.; Carvalho Oliveira, M.M.C.; Ramirez, Javier Alberto; Galagovsky, Lydia Raquel 28-Homocastasterone (28-HCTS), a brassinosteroid, was used to treat in vitro-grown shoots of a hybrid between Eucalyptus grandis and E. urophylla. Treated shoots showed enhanced elongation and formation of new main shoots (the shoots originating directly from the initial explant) at low doses. Coincidently, there was reduced elongation and formation of primary lateral shoots (shoots originating from the main shoot). However, a 5α-monofluoro derivative of 28-HCTS (5F-HCTS) was unable to either stimulate elongation or formation of new main shoots, although it did stimulate elongation of primary lateral shoots. In conclusion, it is quite apparent that exogenously supplied brassinosteroids are able to change shooting patterns in Eucalyptus. These findings have practical biotechnological applications, for example on the improvement of micropropagation techniques for clonal propagation of woody angiosperms. © Springer Science+Business Media B.V. 2006.

Xylene isomerization in a membrane reactor. Part I: The synthesis of MFI membranes for the p-xylene separation Tarditi, Ana Maria; Irusta, Silvia; Lombardo, Eduardo Agustin The synthesis and characterization of silicalite and ZSM-5 films supported on porous SS tubes are described. Composite membranes were used to separate xylene isomers between 150 and 400 °C. Permeation measurements of the individual isomers and the ternary mixture were performed at each temperature within this interval. N2 permeation measurements together with SEM observations were used to determine whether or not cracks and/or pinholes developed after exposure to the xylene isomers at high temperature. The ZSM-5 membrane was superior to the silicalite one because of its higher permeance flux (1.16 × 10-5 mol s-1 m-2), separation factors (p/o 4.4), and up to 400 °C stability.

Selective migration and engraftment of bone marrow mesenchymal stem cells in rat lumbar dorsal root ganglia after sciatic nerve constriction Coronel, Maria Florencia; Musolino, Patricia Leonor; Villar, Marcelo José Bone marrow mesenchymal stem cells (MSCs) preferentially migrate to the injured hemisphere when administered intravenously to rats with traumatic or ischemic brain injuries. In this study, we have investigated the localization of MSCs injected into the lumbar-4 dorsal root ganglion (L4-DRG) of rats with a sciatic nerve single ligature nerve constriction (SLNC). MSCs were isolated by their adherence to plastic, cultured until confluence and labelled with Hoechst. Animals with a unilateral injection of MSCs were subjected to an ipsilateral, bilateral or contralateral SLNC. After 9 days, they were perfused and the lumbar DRGs were dissected out, cut in a cryostat and observed with a fluorescence microscope. Large numbers of Hoechst-positive cells were observed in the injected L4-DRG, distributed around primary afferent neurons, resembling the anatomical localization of glial cells. In animals with an ipsilateral SLNC, some cells were detected in the ipsilateral L3, L5 or L6-DRGs but not in the contralateral ganglia. In animals with a bilateral lesion, MSCs migrated to both the ipsilateral and contralateral DRGs whereas in animals with a contralateral ligature, MSCs migrated to the contralateral DRGs. These results suggest that MSCs preferentially engraft in DRGs hosting primary sensory neurons affected by a lesion of their peripheral branches. Further studies should be carried out in order to elucidate the molecular mechanisms involved in this migration and homing, in order to evaluate the possible use of MSCs as a new therapeutic strategy for the treatment of peripheral nerve neuropathies.

Photoinduced electron-transfer α-deoxygenation of aldonolactones. Efficient synthesis of 2-deoxy-d-arabino-hexono-1,4-lactone Bordoni, Andrea Veronica; Muchnik, Rosa; Marino, María Carla A photoinduced electron-transfer (PET) reaction was used for the deoxygenation at C-2 of aldonolactones derivatized as 2-O-[3-(trifluoromethyl)benzoyl] or benzoyl esters. By irradiation of different D-galactono- and D-glucono-1,4-derivatives, with a 450 W lamp, using 9-methylcarbazole as photosensitizer, the corresponding 2-deoxy-D-lyxo- and 2-deoxy-D-arabino-hexono-1,4-lactones were efficiently obtained.O-[3-(trifluoromethyl)benzoyl] or benzoyl esters. By irradiation of different D-galactono- and D-glucono-1,4-derivatives, with a 450 W lamp, using 9-methylcarbazole as photosensitizer, the corresponding 2-deoxy-D-lyxo- and 2-deoxy-D-arabino-hexono-1,4-lactones were efficiently obtained.D-lyxo- and 2-deoxy-D-arabino-hexono-1,4-lactones were efficiently obtained.

Sex-related differences in the gastrointestinal disposition of ivermectin in the rat: P-glycoprotein involvement and itraconazole modulation Lifschitz, Adrian Luis; Ballent, Mariana; Virkel, Guillermo Leon; Sallovitz, Juan Manuel; Lanusse, Carlos Edmundo Ivermectin (IVM), a macrocyclic lactone used as antiparasite agent, has been reported as a P‐glycoprotein (P‐gp) substrate. The participation of P‐gp in the IVM excretion process has been previously demonstrated. Sex‐related differences in the kinetic behaviour of some macrocyclic lactone compounds have been observed. The aim of this work was to characterize in‐vivo the comparative gastrointestinal disposition of IVM in male and female rats. The sex‐related influence on the itraconazole (ITZ) modulation of P‐gp‐mediated IVM intestinal transport was also assessed. Sixty Wistar rats (30 male, 30 female) received IVM alone or co‐administered with ITZ. Rats were killed between 6 and 72h after treatment and blood, gastrointestinal tissues and lumen contents were collected. IVM concentrations were determined by high performance liquid chromatography. Substantial sex‐related differences in the IVM disposition kinetics were observed. Higher IVM systemic availability was observed in female rats. The ITZ‐mediated modulation of the IVM disposition kinetics had a differential impact between male and female rats. Co‐administration with ITZ resulted in a marked increase in the IVM concentrations in the wall tissue from different portions of the gastrointestinal tract of male rats. The presence of ITZ induced drastic sex‐related changes on the P‐gp‐mediated IVM gastrointestinal disposition.

Age and growth in Odontocymbiola magellanica (Gastropoda: Volutidae) from Golfo Nuevo, Patagonia, Argentina Bigatti, Gregorio; Penchaszadeh, Pablo Enrique; Cledón, Maximiliano Growth, age and somatic production of the benthic predator Odontocymbiola magellanica were studied in Golfo Nuevo (42S 65W), on the South American Atlantic shelf. Stable oxygen isotope ratios confirmed semiannual formation of internal and external shell growth marks. Mean shell length (SL) of females was 115 and 112 mm for males, while population modal shell-free wet mass (SFWM) was 62.8 g. A Gompertz growth function (SL¥ = 200 mm, K = 0.197, t0 = 5.486) fitted 113 pairs of size-at-age data (12 shells) best. O. magellanica is a long-lived species, reaching up to 20 years of age. The maximum individual somatic production of 29.3 g SFWM per year is attained at 145 mm SL, which corresponds to about 12 years of age. The life span of this volutid seems to be twice compared with other large gastropods. O. magellanica is a valuable and exploitable resource regarding its large size and somatic production, but on the other hand, its slow growth, late maturity and direct development makes it extremely vulnerable to overexploitation.Growth, age and somatic production of the benthic predator Odontocymbiola magellanica were studied in Golfo Nuevo (42S 65W), on the South American Atlantic shelf. Stable oxygen isotope ratios confirmed semiannual formation of internal and external shell growth marks. Mean shell length (SL) of females was 115 and 112 mm for males, while population modal shell-free wet mass (SFWM) was 62.8 g. A Gompertz growth function (SL¥ = 200 mm, K = 0.197, t0 = 5.486) fitted 113 pairs of size-at-age data (12 shells) best. O. magellanica is a long-lived species, reaching up to 20 years of age. The maximum individual somatic production of 29.3 g SFWM per year is attained at 145 mm SL, which corresponds to about 12 years of age. The life span of this volutid seems to be twice compared with other large gastropods. O. magellanica is a valuable and exploitable resource regarding its large size and somatic production, but on the other hand, its slow growth, late maturity and direct development makes it extremely vulnerable to overexploitation.

Kinetics of phosphate adsorption on goethite: Comparing batch adsorption and ATR-IR measurements Luengo, Carina Vanesa; Brigante, Maximiliano Eduardo; Antelo, Juan; Avena, Marcelo Javier The adsorption kinetics of phosphate on goethite has been studied by batch adsorption experiments and by in situ ATR-IR spectroscopy at different pH, initial phosphate concentrations and stirring rates. Batch adsorption results are very similar to those reported by several authors, and show a rather fast initial adsorption taking place in a few minutes followed by a slower process taking place in days or weeks. The adsorption kinetics could be also monitored by integrating the phosphate signals obtained in ATR-IR experiments, and a very good agreement between both techniques was found. At pH 4.5 two surface complexes, the bidentate nonprotonated (FeO)2PO2 and the bidentate protonated (FeO)2(OH)PO complexes, are formed at the surface. There are small changes in the relative concentrations of these species as the reaction proceeds, and they seem to evolve in time rather independently. At pH 7.5 and 9 the dominating surface species is (FeO)2PO2, which is accompanied by an extra unidentified species at low concentration. They also seem to evolve independently as the reaction proceeds. The results are consistent with a mechanism that involve a fast adsorption followed by a slow diffusion into pores, and are not consistent with surface precipitation of iron phosphate.

Non-interacting dimer kinetics in hypercubic lattices Costanza, Gregorio José; Manzi, Sergio Javier; Pereyra, Victor Daniel The exact formulation of the kinetic of dimer in hypercubic lattices is developed in the framework of the kinetic lattice gas model. The so-called local evolution rules are used to obtain the hierarchy of equation of motion for the correlation functions where processes like adsorption and desorption are included. The hierarchy of equations are truncated using a mean field (m, n) closures which allows the analytical treatment of the system. A general expression for non-interacting dimer isotherm and two particle correlation functions are obtained in hypercubic lattices.

Photoisomerization of Azobenzenes and Spirocompounds in Nematic and in Twisted Nematic Liquid Crystals Bossi, Mariano Luis; Murgida, Daniel Horacio; Aramendia, Pedro Francisco Samples of a nematic mixture of ZLI1132 and of a twisted nematic mixture composed of ZLI1132 and chiral inductor S811, including 1%-10% (w/w) 4-N,N-dimethylaminoazobenzene (DAB), (4′-nitro)-4-N,Ndimethylaminoazobenzene (NDAB), spiropyran (SP), or spirooxazine (SO) were irradiated to produce the photochromic transformation of the dopant. The changes in the system were monitored by time-resolved transmission spectroscopy, time-resolved birefringence, or polarized Raman scattering. The medium sensitivity of the kinetics and spectroscopy of some of the probes was used to derive information on polarity of the medium. In the systems studied, apart from the changes in absorption spectrum, great changes in birefringence can be photoinduced and the order of the nematic phase can be changed in either direction, depending on the dopant. The open form of SP can discriminate orientation polarity. Although the polarity parallel to the mesogenic director is similar to that for acetone, the perpendicular orientation has a polarity similar to acetonitrile. In agreement with this observation, the kinetics of the Z f E isomerization of NDAB, oriented parallel to the mesogenic director, also experiences a polarity similar to that for acetone. The decay rate constant of the open form of SP displays a linear relationship between its Arrhenius parameters, which is universal in a great variety of homogeneous solvents, solvent mixtures, and liquid crystals, therefore validating the hypothesis that the same type of transformation is observed in all these cases, namely, the decay of the open form monomer. The dopants used have been proven to be adequate probes of bulklike properties in locally heterogeneous systems as liquid crystals.

Sea quark polarization and semi-inclusive DIS data Jiang, X.; Navarro, Gabriela Alejandra; Sassot, Rodolfo We investigate the potential impact of forthcoming Jefferson Lab semi-inclusive polarized deep inelastic scattering proton measurements in the determination of the sea quark polarization in the nucleons by means of a next to leading order global QCD analysis. Specifically, we estimate the resulting improvement in the constraints on polarized parton densities for different flavors, which is found to be significant for up and strange quarks, and the correlation between remaining uncertainty ranges for each of the parton species.

Spin-charge separation and topological phase transitions in Aharonov-Bohm rings of interacting electrons Normand, B.; Hallberg, Karen Astrid; Aligia, Armando Ángel; Kampf, A. P. We investigate the properties of strongly correlated electronic models on a flux-threaded ring connected to semi-infinite free-electron leads. The interference pattern of such an Aharonov-Bohm ring shows sharp dips at certain flux values, determined by the filling, which are a consequence of spin-charge separation in a nanoscopic system. The conductance through such a molecule or nanodevice is related directly to its spectroscopic properties, opening new experimental possibilities for probing the phenomenology of strongly interacting systems. As a further example, for a ring described by the half-filled ionic Hubbard model we show that the weight of the first conductance peak as a function of gate voltage or external flux allows one to identify the topological charge transition between a correlated insulator and a band insulator.

High level expression of bioactive recombinant human growth hormone in the milk of a cloned transgenic cow Salamone, Daniel Felipe; Barañao, Jose Lino Salvador; Santos, Claudio; Bussmann, Leonardo Edmundo; Artuso, Jorge; Werning, Carlos; Prync, Aida; Carbonetto, Cesar; Dabsys, Susana; Munar, Carlos; Salaberry R; Berra, Guillermo; Berra, Ignacio; Fernández, Nahuel; Papouchado, Mariana; Foti, Marcelo; Judewicz, Norberto; Mujica, Ignacio; Muñoz, Luciana; Fernandez Alvarez, Silvina; González, Eliseo; Zimmermann, Juan; Criscuolo, Marcelo; Melo, Carlos Transgenic farm animals have been proposed as an alternative to current bioreactors for large scale production of biopharmaceuticals. However, the efficiency of both methods in the production of the same protein has not yet been established. Here we report the production of recombinant human growth hormone (hGH) in the milk of a cloned transgenic cow at levels of up to 5 g l(-1). The hormone is identical to that currently produced by expression in E. coli. In addition, the hematological and somatometric parameters of the cloned transgenic cow are within the normal range for the breed and it is fertile and capable of producing normal offspring. These results demonstrate that transgenic cattle can be used as a cost-effective alternative for the production of this hormone.

24-hour rhythms of splenic mitogenic responses, lymphocyte subset populations and interferon γ release after calorie restriction or social isolation of rats Cano, Pilar; Cardinali, Daniel Pedro; Fernández, Pilar; Reyes Toso, Carlos Felipe To assess the effect of calorie restriction equivalent to a 66% food restriction or social isolation on splenic immune responses, calorie-restricted five week-old male Wistar rats, pair fed controls individually caged and pair fed controls caged in groups, were studied for four weeks. Calorie restricted and isolated rats showed increased splenic concanavalin A response with peak activity during the activity span. Mean 24 h values of splenic lipopolysaccharide response decreased in isolated rats compared to grouped rats. The highest values of T cells occurred in calorie restricted rats and those of B cells in isolated rats. Mean values of splenic CD4+ and CD8+ cells augmented in isolated or calorie restricted groups. The highest in vitro interferon-gamma production occurred in the isolated group and the lowest in the grouped rats, the differences among groups being significant. Both experimental procedures generally disrupted 24-h rhythmicity of splenic immune parameters. Mean values of plasma corticosterone were higher in calorie restricted rats than in isolated rats and both differed significantly from grouped rats. The results indicate that either calorie restriction or social isolation augmented cell-mediated immunity in rat spleen.

PROPAT: A study to improve the quality and reduce the cost of diabetes care Gagliardino, Juan Jose; Olivera, E.; Etchegoyen, Graciela Susana; Guidi, Mabel Leticia; Caporale, J. E.; Martella, A.; De La Hera, M.; Siri, F.; Bonelli, P. Objective: In PROPAT we implemented an integrated approach to diabetes care designed to improve the quality and reduce the cost of care. Study design and methods: PROPAT was a case-control study matching patients by age and gender (diabetes:control ratio 1:2) within IOMA, a public employment-based health maintenance organization (HMO) of the Province of Buenos Aires, Argentina. Costs were evaluated using prevalence data from an HMO perspective. We currently report clinical and biochemical data and costs from the first 297 patients enrolled who completed 1 year in PROPAT, and compare them with those derived from control patients. Results: All recommended practices recorded as care provided at baseline increased significantly 1 year after implementing PROPAT, with a parallel significant improvement in several clinical and biochemical parameters, and markedly lower total annual per capita costs. Conclusions: These results demonstrate that the implementation of a comprehensive diabetes care program can simultaneously improve quality while reducing costs.

Preferencia alimentaria de arañas Misumenops pallidus (Araneae: Thomisidae) sobre potenciales insectos presa de cultivos de alfalfa; Feeding preferences of the spider Misumenops pallidus (Araneae: Thomisidae) on potential prey insects from alfalfa crops Cheli, German Horacio; Armendano, Andrea Viviana; Gonzalez, Alda Feeding preferences of the spider Misumenops pallidus (Araneae: Thomisidae) on potential prey insects from alfalfa crops. The spider Misumenops pallidus (Thomisidae) is commonly found in alfalfa crops. We studied its predatory preferences on potential insect prey, particularly regarding agroecosystems pests. Two kinds of tests were done under normal laboratory conditions: simultaneous presentation of prey (n= 215) and alternative prey test (n= 45). The spiders preferred insects that were mobile, small, without defensive glands and with thin exoskeletons. According to the amount of prey consumed, we established four predation levels: high (> 55%, on adult Drosophila melanogaster flies); intermediate (30% -55% on the defoliator larvae of Rachiplusia nu and adult heteropterans: Horciasinus argentinus and Halticus spegazzinii); and low (10%- 30% on the chrysomelids Colapsis sp. and Diabrotica speciosa). The pentatomid Piezodorus guildinii, the curculionid Naupactus sp. and the aphid Acyrthosiphom pisum were not accepted as food. Once the spider captured a prey item it did not accept another, independently of prey item species (82% of trials).

Antimicrobial activity of glycosidase inhibitory protein isolated from Cyphomandra betacea Sendt. fruit Ordóñez, Roxana Mabel; Ordóñez, Adriana; Sayago, Jorge Esteban; Nieva Moreno, María Inés; Isla, Maria Ines Broad-spectrum antimicrobial activity of an invertase inhibitory protein (IIP) isolated from Cyphomandra betacea ripe fruits is documented. Minimal inhibitory concentration (MIC) values were determined by agar macrodilution and broth microdilution assays. This IIP inhibited the growth of xylophagous and phytopatogenic fungi (Ganoderma applanatum, Schizophyllum commune, Lenzites elegans, Pycnoporus sanguineous, Penicillium notatum, Aspergillus niger, Phomopsis sojae and Fusarium mango) and phytopathogenic bacteria (Xanthomonas campestris pvar vesicatoria CECT 792, Pseudomonas solanacearum CECT 125, Pseudomonas corrugata CECT 124, Pseudomonas syringae pv. syringae and Erwinia carotovora var carotovora). The IIP concentration required to completely inhibit the growth of all studied fungi ranged from 7.8 to 62.5 μg/ml. Phytopatogenic bacteria were the most sensitive, with MIC values between 7.8 and 31.25 μg/ml. Antifungal and antibacterial activities can be associated with their ability to inhibit hydrolytic enzymes. Our results indicate the possible participation of IIP in the plant defense mechanism and its potential application as a biocontrol agent against phytopathogenic fungi and bacteria. © 2005 Elsevier Inc. All rights reserved.

A rare endemic land-snail from Argentina: Plagiodontes rocae Doering 1881 (Gastropoda: Orthalicidae: Odontostominae) Piza, Julia; Ghezzi, Natalia S; Cazzaniga, Néstor Jorge Plagiodontes rocae Doering 1881 is a strictly endemic species from the Paleozoic mountains of southern Buenos Aires province (Argentina). Its identity has been never controversial, but its description and discrimination from related species was still incomplete. A quantitative analysis of its measurements was advisable to locate the species in the frame of a morphological re-analysis of all species in genus Plagiodontes Doering1876. In this study, Protoconch sculpture is illustrated by SEM micrographs to rectify previous descriptions. Shell measurements and angles are studied by Multivariate Discriminant Analysis to discriminate it from other small-sized species. Genital anatomy of P. rocae is described for the first time, its quantitative data being discriminated by multivariate methods from those of the only co-existing Odontostominae, i.e., Plagiodontes pat-agonicus.; Plagiodontes rocae Doering 1881 ist eine endemische Art des paläozoischen Berglandes im Süden der Provinz Buenos Aires, Argentinien. Ihr Status als eigenständige Art ist nie in Frage gestellt worden, doch ist ihre Beschreibung und Differenzierung von nahestehenden Arten nicht abgeschlossen. Im Rahmen der Revision aller Plagiodontes-Arten, die wir derzeit durchführen, ist daher eine morphometrische Analyse angebracht, um die Art korrekt einzuordnen. Die Skulptur des Embryonalgehäuses wird mittels SEM-Mikrographie dargestellt. Gehäusemaße und -winkel werden mit Hilfe der Multivariaten Diskriminanzanalyse mit denen anderer kleingehäusiger Arten verglichen. Die Genitalanatomie von P. rocae wird hier zum ersten Mal beschrieben; ihre morphometrischen Daten werden mit Hilfe der Multivarianzanalyse mit P. patagonicus, des einzigen sympatrischen Vertreters der Odontostominae, verglichen.

Los cerraminetos verticales en tierra y su eficiencia economico-tecnologico-termico-energetica Garzon, Beatriz Silvia Se describe la adecuación bioambiental de las soluciones autóctonas de disposiciones tecnológicas de cerramientos verticales y las características económico-tecnológico-constructivas, consumo energético de producción, y la determinación de la eficiencia ecológica-térmico-energética de las alternativas planteadas(mampostería de adobe y paneles de madera, caña y barro), la verificación según normas de comportamiento térmico y su comparación con relación a los sistemas tecnológicos convencionales con los cuales se resuelven, en la mayoría de los casos, las viviendas de interés social, planteadas para estas comunidades desde otros sectores (oficial, privado, etc.).

Fully differential cross sections for C6+ single ionization of helium: The role of nucleus-nucleus interaction Ciappina, Marcelo Fabián; Cravero, Walter Ruben In this work, we present fully differential cross section (FDCS) calculations using distorted wave theories for helium single ionization by 2 MeV amu-1 C6+ ions. We study the influence of internuclear interaction on low-energy electron emission in the scattering plane. It is shown that by incorporating an internuclear effective charge which depends on the collision momentum transfer and taking into account its interplay with passive electron screening we obtain better agreement with experiments in most cases under consideration. Comparisons are made with absolute experimental measurements and with other theories. We found that for ejected-electron momentum similar to transferred momentum, internuclear potential effects have little contribution to FDCSs.