A new theoretical approach to multilayer adsorption of polyatomics Romá, Federico José; Ramirez Pastor, Antonio Jose; Riccardo, Jose Luis The multilayer adsorption isotherms of linear particles (k-mers) on homogeneous surfaces were developed on a generalization in the spirit of the well-known Brunauer-Emmet-Teller's approach. The generalized equation is obtained through an analytical approach that provides the isotherm in the multilayer regime from the isotherm in the monolayer regime. The formalism leads to exact results in one dimension and provides an analytical approximation to study multilayer adsorption on two-dimensional surfaces with different geometries (square, honeycomb and triangular). The entropic effects of the nonspherical character of the adparticles on the determination of the monolayer volume and adsorption energy, are shown and discussed for type II and type III isotherms. Comparison with Monte Carlo simulations in the grand canonical ensemble and experimental adsorption isotherms are used to test the accuracy and reliability of the model. Close agreement between simulated, theoretical and experimental results supports the applicability of the proposed model to describe multilayer adsorption in presence of multisite-occupancy.

Cytotoxic T lymphocyte antigen 4 heterozygous codon 49 A/G dimorphism is associated to latent autoimmune diabetes in adults (LADA) Caputo, Mariela; Cerrone, Gloria Edith; Lopez, Ariel Pablo; Villalba, Anabel; Krochik, Andrea Gabriela; Cédola, Federico Norberto; Targovnik, Hector Manuel; Frechtel, Gustavo Daniel Autoimmune diabetes is an organ specific and multifactorial disorder with a classical onset as insulin dependent diabetes mellitus (IDDM) and with another form of onset as latent autoimmune diabetes in adults (LADA), which has a slower onset and a later progress to insulin dependency as a result of the beta cells destruction. The cytotoxic T lymphocyte-antigen 4 (CTLA4) has been identified as a susceptible marker of the disease; it is considered a down regulator of T cell function, playing a key role in autoimmunity. We analyzed CTLA4 codon 49 A/G polymorphism in 123 IDDM patients, 63 LADA patients and 168 healthy non-diabetic control individuals. The frequency of the heterozygous A/G genotype in LADA patients was significantly increased compared to IDDM patients (55.6 vs. 39.8%, p = 0.0415). There was no statistical significant difference in the distribution of the A/G dimorphism between autoimmune diabetes patients (LADA or IDDM) and non-diabetic control individuals. HLA DQ region is responsible for the genetic susceptibility to autoimmune diabetes in IDDM patients in about 50% and it has a lower effect in genetic susceptibility in LADA patients. Several other genetic loci are needed to develop autoimmune diabetes in adult patients. Therefore, LADA may be the result of a combined minor risk loci effect in a major risk haplotype.

Biocontrol of Bacillus subtilis against Fusarium verticillioides in vitro and at maize root level Cavaglieri, Lilia Reneé; Orlando, Julieta Laura; Rodriguez, Maria Ines; Chulze, Sofia Noemi; Etcheverry, Miriam Graciela Bacillus species as a group offer several advantages over other bacteria for protection against root pathogens because of their ability to form endospores, and because of the broad-spectrum activity of their antibiotics. The objectives of this work were to determine the ability of strains of Bacillus to inhibit Fusarium verticillioides growth and fumonisin B1 accumulation in vitro, and to evaluate the ability of the best bacterium for preventing rhizosphere and endorhizosphere colonization by F. verticillioides. Bacterial populations from the maize rhizoplane were obtained, and the capacity of ten Bacillus strains to inhibit fungal growth and fumonisin B1 accumulation in vitro was assayed. According to these results, B. subtilis CE1 was selected as the best antagonist for testing maize root colonization of F. verticillioides. Bacillus subtilis CE1 at 108 and 107 CFUml-1 inocula was able to reduce rhizoplane and endorhizosphere colonization of F. verticillioides in greenhouse trials. The strain B. subtilis CE1 could be a potential biological control agent against F. verticillioides at the root level.

Pricing of Defaultable Bonds with Log-Normal Spread: Development of the Model and an Application to Argentinean and Brazilian Bonds During the Argentine Crisis Cané de Estrada, Mariano; Cortina, Elsa Aurora; Ferro Fontan, Constantino; Fiori, Javier di In this paper we describe a two-factor model for a defaultable discount bond, assuming log-normal dynamics with bounded volatility for the instantaneous short rate spread. Under some simplified hypothesis, we obtain an explicit barrier-type solution for zero recovery and constant recovery. We also present a numerical application for Argentinean and Brazilian Sovereign Bonds during the default crisis of Argentina.

Dynamic Modelling and Optimisation of Large-Scale Cryogenic Separation Processes Rodriguez, Mariela Alejandra; Bandoni, Jose Alberto; Díaz, María Soledad In this work, the open loop dynamic optimisation of a large-scale natural gas processing plant is performed. A rigorous differential-algebraic equation (DAE) model has been formulated to represent main plant units, such as shell and tube heat exchangers, highpressure separator and demethanizing column. In the shell and tube heat exchangers, the hot stream partially condenses and equations to consider the partial condensation of the fluids have been included. A rigorous index one model for the demethanizing column has been developed. The DAE optimisation problem is solved with a simultaneous approach, in which both state and control variables are discretised and the original DAE optimisation model is transformed into a large-scale nonlinear problem (NLP), which is solved using Sequential Quadratic Programming (SQP) methods. Optimal profiles have been obtained for main operating variables to achieve an enhanced product recovery.

Effect of pretreatments and processing conditions on the chemical, physical, microbiological and sensory characteristics of garlic paste Constenla, Diana Teresita; Lozano, Jorge Enrique The influence of storage temperature of garlic bulb and chemical additives (including ascorbic acid, citric acid and potassium sorbate) on the chemical, physical, microbiological and sensory characteristics of garlic paste was evaluated. Formation of undesirable greenish pigment was avoided by storing fresh garlic bulbs at 25 and 40C. Moreover, heating bulbs to 40C a few minutes before processing facilitated skin removal. Garlic paste was processed, packed and thermally treated at 85C for 5 min. The color of garlic paste was affected by chemical treatment, temperature and storage period. The rate of color difference (ΔE) increase was divided into two linear periods with different slopes. Garlic paste exhibited pseudoplasticity with yield stress and flow adequately described by the Herschel-Bulkley model (r2 > 0.990). Both consistency index and apparent viscosity decreased with increase in temperature.

Boundary element method for J-integral and stress intensity factor computations in three-dimensional interface cracks Ortiz, Jhonny E.; Cisilino, Adrian Pablo A general numerical tool for the analysis of three–dimensional bimaterial interface cracks is presented in this paper. The proposed tool is based on a multidomain formulation of the Boundary Element Method (BEM), with the crack located at the interface of the domain. Mixed mode stress intensity factors are computed along the three-dimensional crack fronts using the Energy Domain Integral (EDI) methodology and decoupled via the Interaction Integral. The capability of the procedure is demonstrated by solving a number of examples. The last of these examples consists in a thick centre cracked panel for which the behaviour of the J-integral and the mixed-mode stress intensity factors along the crack front is studied as a function of the material mismatch.

Allylic alcohol synthesis by gas-phase hydrogen transfer reduction of unsaturated ketones Di Cosimo, Juana Isabel; Acosta, A.; Apesteguia, Carlos Rodolfo The gas-phase hydrogen transfer reduction (HTR) of mesityl oxide (MO) with 2-propanol to selectively obtain allylic alcohols was studied on MgO. MO was converted directly to 4-methyl-3-penten-2ol (UOL1) or isomerised to iso-mesityl oxide (i-MO), which consecutively formed 4-methyl-4-penten-2ol (UOL2). Significant amounts of methyl isobutyl carbinol (MIBC) were also formed by the simultaneous reduction of CC and CO groups of MO. The effect of reaction conditions on catalyst activity and selectivity was determined in order to improve total UOL yield that was about 28% under standard reaction conditions (T = 523 K, 2-propanol/MO = 5, W/FMO0 = 15 g h/mol). Total UOL yield increased continuously with contact time up to 42% but when the 2-propanol/MO ratio was varied, UOL yield reached a maximum at a reactant ratio of about 4. UOL2 yield markedly increased with temperature at expenses of MIBC. The increase of temperature also improved the catalyst stability because suppressed formation of coke intermediates. Regarding the effect of the hydrogen donor, higher total UOL yields were obtained by using secondary alcohols, such as 2-propanol and 2-butanol, than primary (1-propanol) or secondary aryl (1-penylethanol) alcohols.

Additive apoptotic effect of STI571 with the cytoprotective agent amifostine in K-562 cell line Vellón, Luciano; Gonzalez Cid, Marcela Beatriz; de Campos Nebel, Ildefonso Marcelo; Larripa, Irene Beatriz Purpose: To study the apoptotic effect of the 2-phenylaminopyrimidine derivative STI571 in combination with antioxidant agents on K-562 cell line derived from a Philadelphia chromosome-positive chronic myeloid leukemia patient. Materials and methods: K-562 (BCR/ABL+), U-937, and HL60 (BCR/ABL-) leukemic cell lines were incubated with STI571 and the antioxidant agents catalase, glutathione, superoxide dismutase, and amifostine (AMI). Apoptotic effect was analyzed by morphological and flow cytometric criteria. Results: STI571 at concentrations higher than 0.25 μmol L-1 produced apoptosis (P<0.05) in K-562 cells only after treatment for 72 h. At the mentioned concentrations, STI571 also induced an increase in the loss of mitochondrial transmembrane potential from 24.6 to 40%. Combination of STI571 (0.5 μmol L-1) with antioxidant agents showed that the cytoprotective agent AMI (0.75 mg mL-1) produced an additive effect in the proapoptotic activity of STI571 in K-562 cells at nuclear (58.8%±2.0 vs. 28.9%±3.3) and mitochondrial (53.3%±3.6 vs. 29.5%±1.2) levels. Conclusions: Our results show that only AMI in combination with STI571, at submicromolar concentration, has an additive effect in K-562 cell line, and it does not have severe toxic effects on Philadelphia chromosome negative cells. © Springer-Verlag 2005.

Administration of a peptide inhibitor of alpha4-integrin inhibits the development of experimental autoimmune uveitis Martín, Andrea P.; Vieira de Moraes, Luciana; Tadokoro, Carlos E.; Commodaro, Alessandra G.; Urrets Zavalia, Enrique; Rabinovich, Gabriel Adrián; Urrets Zavalía, Julio Alberto; Rizzo, Luiz V.; Serra, Horacio Marcelo Recruitment of lymphocytes into the retina and to the vitreous during the development of experimental autoimmune uveitis (EAU) is governed by factors such as the state of activation of inflammatory cells and the repertoire of adhesion molecules expressed by the local vascular endothelia. alpha4 Integrins and their receptors play an important role during homing of cells to the inflammatory site. In the present study, the effect of alpha4-integrin inhibitor on the development of EAU was investigated.

Acanthagrion hartei sp. nov. from Ecuador (Zygoptera: Coenagrionidae) Muzon, Javier; Lozano, Federico The new sp. is described and illustrated. Holotype: Ecuador, Morona, Santiago prov., Bomboiza, 20-IX-1990, deposited in USNM, Washington. It is assigned to the apicale-group, and differs from the other spp. of that group by characters of the terminalia and genital ligula.

O impacto do rio da Prata no oceano Atlântico Piola, Alberto Ricardo; Möller, Osmar O.; Palma, Elbio Daniel Os habitantes da região costeira que se estende da província de Buenos Aires, na Argentina, a Rio Grande, no sul do Brasil, sabem que a água do mar é quase 10°C mais quente em janeiro que em julho. Um observador mais atento notaria também mudanças de cor na sua superfície em diferentes épocas do ano. Para explicar tais observações, especula-se sobre a existência de freqüentes incursões de água fria oriundas da corrente das Malvinas. Neste artigo são apresentadas evidências que sugerem que as alterações mais importantes ao longo de uma faixa costeira de aproximadamente 1.000 km se devem à influência variável das águas que o rio da Prata derrama no oceano Atlântico.

Antithrombogenic properties of bioconjugate streptokinase-polyglycerol dendrimers Ramos Fernandes, Edson Giuliani; de Queiroz, Alvaro Antonio Alencar; Abraham, Gustavo Abel; San Román, Julio Dendrimers are monodisperse, spherical and hyperbranched synthetic macromolecules with a large number of surface groups that have the potential to act as carriers for drug immobilization by covalent binding or charge transfer complexation. In this work, a bioconjugate of streptokinase and a polyglycerol dendrimer (PGLD) generation 5 was used to obtain fibrinolytic surfaces. The PGLD dendrimer was synthesized by the ring opening polymerization of deprotonated glycidol using polyglycerol as core functionality in a step-growth processes denominated divergent synthesis. The PGLD dendritic structure was confirmed by gel permeation chromatography (GPC), nuclear magnetic resonance (1H-NMR, 13C-NMR) and matrix assisted laser desorption/ionization (MALDI-TOF) techniques. The synthesized dendrimer presented low dispersion in molecular weights (Mw/Mn = 1.05) and a degree of branching of 0.82 which characterize the polymer dendritic structure. The blood compatibility of the bioconjugate PGLD-Sk was evaluated by in vitro assays such as platelet adhesion and thrombus formation. Uncoated polystyrene –microtitre plates (ELISA) was used as reference. The epifluorescence microscopy results indicate that PGLD-Sk coating showed an improved antithrombogenic character relative to the uncoated ELISA plates.

Galectins as immunoregulators during infectious processes: from microbial invasion to the resolution of the disease Rabinovich, Gabriel Adrián; Gruppi, Adriana Recent evidence has implicated galectins, a family of evolutionarily conserved carbohydrate-binding proteins, as regulators of immune cell homeostasis and host-pathogen interactions. Galectins operate at different levels of innate and adaptive immune responses, by modulating cell survival and cell activation or by influencing the Th1/Th2 cytokine balance. Furthermore, galectins may contribute to host-pathogen recognition and may serve as receptors for specific interactions of pathogens with their insect vectors. Here we will explore the influence of galectins in immunological processes relevant to microbial infection and will summarize exciting recent work related to the specific interactions between galectins and their glycoconjugate ligands as critical determinants of pathogen recognition. Understanding the role of galectin-sugar interactions during the course of microbial infections might contribute to defining novel targets for disease prevention and immune intervention.

Compressional and shear wave velocities in uncemented sediment containing gas hydrate Yun, Tae Sup; Francisca, Franco Matias; Santamarina, J. Carlos; Ruppel, Carola The competing hypotheses for gas hydrate formation at the particle scale in sediments describe processes of pore-filling, frame-building, or cementation. New measurements of compressional (VP) and shear wave (VS) velocities in fine-grained sands subjected to low confinement and monitored during formation of tetrahydrofuran hydrate indicate that hydrate nucleates in the pore space (presumably at grain boundaries) and grows with limited impact on the sediment shear stiffness, VP, and VS until crystals begin to interact with the granular skeleton at ∼40% hydrate concentration. VS increases significantly more than VP at higher hydrate concentrations, reflecting larger changes in the specimen's shear stiffness than its bulk stiffness. The results indicate that seismic velocities and/or their ratio (VP/VS) have limited capability for locating hydrate or constraining hydrate concentrations.

Rendimiento de la técnica de enjambrado artificial como alternativa para el control de Loque Americana Albo, Graciela Noemí; Reynaldi, Francisco José; Casanova, Luciana; Dimenna, S. E. La loque americana (LA) una enfermedad causada por la bacteria esporulada Paenibacillus larvae subsp. larvae  que se encuentra ampliamente distribuida tanto a nivel mundial  como en Argentina. Los objetivos del presente trabajo fueron: 1- Evaluar el rendimiento de la técnica de enjambrado artificial en otoño, con y sin el agregado de antibióticos, a través de la medición porcentual de recurrencia de la enfermedad y la muerte de colonias. 2- Determinar el gasto de alimento artificial (energético y proteico) para obtener un  desarrollo satisfactorio del paquete. La técnica de enjambrado artificial sólo resulta exitosa con el uso de antibiítico lueo del paqueteado en colmenas con una infección sobre la cría no mayor a grado 2 y con una población de abejas adultas no inferior a nivel 2. El porcentaje de recurrencia  es del 1%.

Effects of pH and ionic strength on the adsorption of phosphate and arsenate at the goethite-water interface Antelo, Juan; Avena, Marcelo Javier; Fiol, Sarah; López, Rocío; Arce, Florencio The surface properties of a well-crystallized synthetic goethite have been studied by acid-base potentiometric titrations, electrophoresis, and phosphate and arsenate adsorption isotherms at different pH and electrolyte concentrations. The PZC and IEP of the studied goethite were 9.3±0.1 and 9.3±0.2, respectively. Phosphate and arsenate adsorption decrease as the pH increases in either 0.1 or 0.01 M KNO3 solutions. Phosphate adsorption is more sensitive to changes in pH and ionic strength than that of arsenate. The combined effects of pH and ionic strength result in higher phosphate adsorption in acidic media at most ionic strengths, but result in lower phosphate adsorption in basic media and low ionic strengths. The CD-MUSIC model yields rather good fit of the experimental data. For phosphate it was necessary to postulate the presence of three inner-sphere surface complexes (monodentate nonprotonated, bidentate nonprotonated, and bidentate protonated). In contrast, arsenate could be well described by postulating only the presence of the two bidenate species. A small improvement of the arsenate adsorption data could be achieved by assuming the presence of a monodentate protonated species. Model predictions are in agreement with spectroscopic evidence, which suggest, especially for the case of arsenate, that mainly bidentate inner-sphere complexes are formed at the goethite-water interface.

Increased Monooxygenase Activity Associated with Resistance to Permethrin in Pediculus humanus capitis (Anoplura: Pediculidae) from Argentina Gonzalez Audino, Paola Andrea; Barrios, S.; Vassena, Claudia Viviana; Mougabure Cueto, Gastón Adolfo; Zerba, Eduardo Nicolás; Picollo, Maria Ines We studied the profile of permethrin resistance in head lice populations infesting children 6-12 years old in schools and children´s homes in & around Buenos Aires, Argentina. Five permethrin resistant populations with different levels of resistance -Hogar Loyola (HL), Republica de Turquia (RT), Hogar Mitre (HM), Guardia de Honor (GH), Ricardo Guiraldes (RG)- and one susceptible population, Bandera Argentina (BA) were collected. Their level of resistance was evaluated and results showed resistance ratios (RR) of 13 for HL, 16 for RT, 22 for HM, 61 for GH and 69 for RG. In order to elucidate the possible involvement of the cytochrome P450 monooxygenase system in conferring permethrin resistance, ethoxycoumarin-O-deethylase (ECOD) activity was measured in abdomens of individual third instar nymphs and adults using a fluorometric assay.  The ECOD activity was lower in the susceptible BA population (4.7 ng/insect) than in the resistant ones (13.7 ng/insect for RG, 12.3 ng/insect for GH, 8.6 ng/insect for RT, 8.2 ng/insect for HL). ECOD activity was significantly correlated with the level of resistance in the field populations (r= 0.97, p=0.0009) suggesting a role for cytochrome monooxygenase P450 system in permethrin resistance by P. humanus capitis.

Sorghum kernel weight: Growth patterns from different positions within the panicle Gambin, Brenda Laura; Borras, Lucas The influence of genotype and panicle position on sorghum [Sorghum bicolor (L.) Moench] kernel growth is poorly understood. In the present study, sorghum kernel weight (KW) differences during grain filling were analyzed by kernel water relationships previously described in other crops. Eight commercial genotypes differing in KW were used, and KW, water content, kernel volume, kernel moisture content, and kernel density were measured in two positions within the panicle (apical and basal) throughout the grain-filling period. At physiological maturity (PM), KW ranged from 16.5 to 25.1 mg kernel-1, and a significant (p < 0.05) genotype x position interaction was detected. Independently of final KW, apical kernels always exhibited a higher rate (p < 0.001) and a shorter duration of grain filling (p < 0.001) than basal kernels. Maximum water content was related to kernel growth rate but not to final KW. Basal kernels reached maximum kernel volume after attaining maximum water content, with dry matter accumulation affecting kernel volume determination. Kernel density increased with a similar pattern regardless of genotype or panicle position when related to the kernel moisture decline, but at PM, basal kernels were always more dense than apical ones. Differences in the kernel desiccation pattern and in the critical moisture content for biomass accumulation helped explain differences in the grain-filling duration between positions. A general kernel growth curve based on kernel moisture content was impossible to obtain because of the differences in kernel growth patterns within the panicle.

Acerca de la inevitabilidad de la interpretación jurídica Navarro, Pablo Eugenio El objetivo principal de este trabajo es clarificar y refutar la tesis de la indeterminacion interpetativa (TI). Sin embargo, este trabajo no pretende ofrecer un argumento definitivo contra ninguna escuela o doctrina particular, sino que trata de iluminar rasgos del derecho que han sido indebidamente pasados por alto o que han sido descuidados en el debate contemporáneo. En gran medida, TI parece plausible por la ambigüedad sistemática en que son utilizadas algunas de las principales expresiones en cuestión, i.e., ?caso?, ?norma general?, norma ?individual?, etc. Una vez que se despejan las confusiones que subyacen a TI también es posible advertir por qué razón es frecuente considerar imprescindible a la interpretación de las normas jurídicas, y en qué sentido TI es una exageración de otras ideas valiosas para el análisis de la identificación y aplicación del derecho