Historia epidemiológica de la tuberculosis en la Argentina. 1914-1947 Carbonetti, Adrian En el presente trabajo se analiza la mortalidad por tuberculosis en la República Argentina en el período comprendido entre 1914 y 1947. Esta etapa tiene fundamental importancia debido a que en ella se dio el mayor crecimiento de la mortalidad por esta enfermedad (1918) y luego un declive hasta llegar a valores mínimos en 1947. El comportamiento de la tuberculosis es coincidente con el proceso de transición epidemiológica que sufre la población argentina en este período de tiempo. Se analizan las tasas de mortalidad por tuberculosis a lo largo del período, se estudia la mortalidad por esta enfermedad según edad y sexo y se describe el recorrido de la mortalidad según las distintas regiones del territorio nacional.; In the present work the mortality analyzes for tuberculosis in the Republic Argentina in the period understood between 1914 and 1947. This stage has fundamental importance due to the fact that in her one gave the major growth of the mortality for this disease (1918) and then a decline up to coming to minimal values in 1947. The behavior of the tuberculosis is coincidental with the process of epidemiological transition that the Argentine population suffers in this period of time. The rates of mortality are analyzed by tuberculosis throughout the period, the mortality is studied by this disease according to age and sex and the tour of the mortality is described according to the different regions of the national territory.

Eugenia Sacerdote de Lustig: mujeres pioneras de la investigación oncológica Pérgola, Federico En los últimos días de noviembre de 2011, exactamente durante el domingo 27, falleció en Buenos Aires la Dra. Eugenia Sacerdote de Lustig. Murió a los 101 años y la sobrevive su prima hermana, algunos meses mayor, la Dra. Rita Levi Montalcini, premio Nobel de Medicina. Soportó discriminaciones, una de ellas por la mente febril de un dictador de turno de su Italia natal, don Benito Mussolini que fue de tipo racial. La otra que suponemos que la hubo, la de género: era mujer y se “atrevía” a investigar en la década del 40 cuando todo era patrimonio masculino.

De la construcción del conocimiento científico a su enseñanza : distintas explicaciones sobre la estructura del benceno; From scientific knowledge construction to teaching. Several explanations about benzene structure Farré, Andrea Soledad; Lorenzo, Maria Gabriela La revisión de la evolución histórica para representar cierto compuesto, en este caso benceno, pone de manifiesto las diferentes teorías que pugnaron por dar las mejores explicaciones, mostrando una visión dinámica acerca de la construcción del conocimiento científico. Los principales factores que han influido sobre el conocimiento acerca de la estructura del benceno son la composición elemental y el establecimiento de la fórmula empírica, el reconocimiento de isómeros, la reactividad química, la disponibilidad de nuevos dispositivos tecnológicos y las teorías de enlace químico (teoría estructural, teorías atómicas, teoría de enlace de valencia y la teoría de orbitales moleculares). Este trabajo podrá ser de utilidad para la capacitación de profesores y tal vez eche luz sobre algunas dificultades de aprendizaje de los estudiantes. También, resulta un modelo útil para que los profesores puedan desarrollar futuras investigaciones junto con sus estudiantes, incluyendo activamente al conocimiento meta-científico en sus prácticas de aula.; From scientific knowledge construction to teaching. Several explanations about benzene structure. Reviewing the historical development to represent a compound, in this case benzene, displays the different theories that struggled to give the best explanations, showing a dynamic vision for the scientific knowledge construction. The elemental composition and the establishment of the empirical formula, the recognition of isomers, the chemical reactivity, the availability of new technological devices and chemical bond theories (the structural theory, atomic theories, valence bond theory and molecular orbital theory) are the main factors that influenced knowledge about the structure of benzene. This work can be useful in teachers’ training and perhaps enlightens on some students learning difficulties. This also is a useful model for future research that teachers can develop with their students including the meta-scientific knowledge actively in the classroom.

The Development of More Accurate QSAR Techniques Lee, Adam; Mercader, Andrew Gustavo; Castro, Eduardo Alberto; Duchowicz, Pablo Román QSAR is a very effective starting step in the development of compounds for vast numbers of industries. Its scale and importance, especially in the medicinal field means it is a dynamic area to research. The size of QSAR also presents problems; there are many different methods in use for each of the steps in a study, from the descriptors in use, to the type of linear regression to apply to the descriptors. The idea was to put forward models that improved upon the existing methods to such a degree that it could become a universal method for QSAR modelling. This project successfully investigated in detail an improvement to the existing methods to choose the correct number of descriptors to include in the model by using Rloo analysis; this resulted in a simpler model compared to previous methods. K – Means clustering was also investigated as part of a novel, variable independent method. This methodology only uses one descriptor as opposed to general QSAR studies which use several. The results for 12 out of the 14 sets were at least as accurate as the results obtained by existing linear methods. An example using PERM; the Stest obtained using the novel method was 0.46 compared to the Stest of 0.53 obtained by using current linear methods. The simplicity associated with the K - Means clustering method and the fact it shows improved predictive potential could lead to an overhaul of all current, more complicated methods in favour of the simpler K- Means based method.

Mating success depends on rearing substrate in cactophilic Drosophila Hurtado, Juan Pablo; Soto, Eduardo Maria; Orellana, Liliana; Hasson, Esteban Ruben Drosophila buzzatii and D. koepferae coexist in the arid lands of southern South America and exploit different types of cactus as breeding hosts. The former prefers to lay eggs on the rotting pads of prickly pears (genus Opuntia) whereas D. koepferae exhibits greater acceptance for columnar cacti (e. g., Echinopsis terschekii). Here, we demonstrate that the rearing cacti affect male mating success, flies reared in each species' preferred host exhibited enhanced mating success than those raised in secondary hosts. Opuntia sulphurea medium endows D. buzzatii males with greater mating ability while D. koepferae males perform better when flies develop in Echinopsis terschekii. These effects are not mediated through body size, even in D. buzzatii whose body size happens to be affected by the rearing cacti. This scenario, which is consistent with the evolution of host specialization and speciation through sensory drive, emphasizes the importance of habitat isolation in the coexistence of these cactophilic Drosophila.

Neuroprotective effects of human umbilical cord mesenchymal stromal cells in an immunocompetent animal model of Parkinson's disease Mathieu, Patricia Andrea; Roca, Valeria Ines; Gamba, Cecilia; del Pozo, Ana; Pitossi, Fernando Juan Microglial activation in the substantia nigra (SN) is a ubiquitous feature in PD which could mediate toxic effects. Human mesenchymal stromal cells (hMSCs) possess immunomodulatory properties. We evaluated whether the transplantation of hMSCs obtained from umbilical cord had a neuroprotective effect in a not-immunosuppressed rat Parkinson's disease (PD) model. Rats receiving hMSCs in the SN displayed significant preservation in the number of dopaminergic neurons in the SN at 21. days after lesion and an improved performance in behavioral tests compared to control rats. However, no differences in any inflammatory parameter tested were found. These results suggest that grafted hMSCs exert neuroprotection but not neuromodulatory effects on degenerating dopaminergic neurons.

Experimental infection of rabbits (Oryctolagus cuniculus) with Brucella suis biovar 1 isolated from wild hares (Lepus europaeus) Fort, Marcelo; Baldone, Valeria; Fuchs, Lumila Ivana; Giménez, Hugo; Rojas, María; Breccia, Javier Dario; Oyhenart, Jorge Brucella suis biovar 1 is the causative agent of brucellosis in several domestic and wild animals and it is a common agent of human brucellosis. European hares (Lepus europaeus) have been shown to be infected by B. suis biovar 1 and the transmission to other animals has been suggested. In this work, experimental rabbits (Cuniculus orictolagus) were infected with B. suis biovar 1 isolated from wild hares. Infected rabbits showed high serological response in 2 weeks after discharge and typical granulomatous lesions (2. mm diameter) were found in liver, spleen and kidneys after 50 days. B. suis biovar 1 was cultured from the lesion of the organs mentioned above as well as from urine, placenta and fetuses. These data suggest that hares are a potential source for horizontal transmission of B. suis biovar 1 to other mammalians.

Efficient energy transfer via the cyanide bridge in dinuclear complexes containing Ru(ii) polypyridine moieties Cadranel, Alejandro; Alborés, Pablo; Yamazaki, Shiori; Kleiman, Valeria D.; Baraldo Victorica, Luis Mario We report the synthesis, structure and properties of the cyanide-bridged dinuclear complex ions [Ru(L)-(bpy)(μ-NC)M(CN)5]2−/− (L = tpy, 2,2′;6′,2′′-terpyridine, or tpm, tris(1-pyrazolyl)methane, bpy = 2,2′- bipyridine, M = Fe(II), Fe(III), Cr(III)) and the related monomers [Ru(L)(bpy)X]2+ (X = CN− and NCS−).All the monomeric compounds are weak MLCT emitters (λ = 650?715 nm, ϕ ≈ 10−4). In the Fe(II) and Cr(III) dinuclear systems, the cyanide bridge promotes efficient energy transfer between the Ru-centered MLCT state and a Fe(II)- or Cr(III)-centered d?d state, which results either in a complete quenching of luminescence or in a narrow red emission (λ ≈ 820 nm, ϕ ≈ 10−3) respectively. In the case of Fe(III) dinuclear systems, an electron transfer quenching process is also likely to occur.

Global W 2,p estimates for nondivergence elliptic operators with potentials satisfying a reverse Hölder condition Bramanti, M.; Brandolini, L.; Harboure, Eleonor Ofelia; Viviani, Beatriz Eleonora In this article, we give some a priori L p(ℝ n) estimates for elliptic operators in nondivergence form with VMO coefficients and a potential V satisfying an appropriate reverse Hölder condition, generalizing previous results due to Chiarenza-Frasca-Longo to the scope of Schrödinger-type operators. In particular, our class of potentials includes unbounded functions such as nonnegative polynomials. We apply such a priori estimates to derive some global existence and uniqueness results under some additional assumptions on V.

Difficulties of undergraduate students in the organic chemistry laboratory Lorenzo, Maria Gabriela; Reverdito, Ana Maria; Blanco, Mercedes; Salerno, Alejandra In order to study the learning difficulties of university students in the organic chemistry laboratory, a new Model for the Analysis of Experimental Work (MAEW) was developed. This article is organized into three parts: first, a historical look at the role of experimental work in science education, including the purpose of the laboratory class; next, a description of the MAEW; finally, we show how the MAEW can be applied to an actual laboratory class of organic chemistry. An original proposal for the classification of the materials used in an organic chemistry laboratory is also offered.

Nucleophile- or light-induced synthesis of 3-substituted phthalides from 2-formylarylketones Gerbino, Darío César; Augner, Daniel; Slavov, Nikolay; Schmalz, Hans Günther The surprisingly facile conversion (isomerization) of 2-formyl-arylketones into 3-substituted phthalides, as observed for the marine natural product pestalone and its per-O-methylated derivative, was investigated using a series of simple 2-acylbenzaldehydes as substrates. The transformation generally proceeds smoothly in DMSO, either in a Cannizarro-Tishchenko-type reaction under nucleophile catalysis (NaCN) or under photochemical conditions (DMSO, 350 nm). © 2012 American Chemical Society.

Assessment of water quality in temperate-plain streams (Argentina, South America) using a multiple approach; Evaluación de la calidad del agua mediante un enfoque múltiple en arroyos de la llanura templada (Argentina, América del Sur) Ocon, Carolina Silvia; Rodrigues Capitulo, Alberto We assessed the water quality in two pampean lotic systems (Argentina), the Juan Blanco and Buñirigo streams, subjected to different land uses (i. e., the UNESCO Biosphere Nature Reserve versus industry and agriculture, respectively) through measurements of physicochemical data and the structural parameters of the macroinvertebrate assemblages in addition to ecotoxicological analyses. The objective was to identify the degree of ecological impairment in adversely affected areas and the consequent effects on the biota. The results obtained allowed the establishment of different water-quality classes within the study area. According to the indices applied, the downstream zone of the Buñirigo stream was categorized as moderately polluted on the basis of losses of sensitive benthic species or changes in their abundance. Likewise, acute ecotoxicological bioassays demonstrated that the water from this site had lethal effects on Caenis nemoralis (Ephemeroptera: Caenidae) larvae. This sampling point also exhibited relevant physicochemical features, such as high water conductivity and nutrient levels as well as low contents of dissolved oxygen.; Se realizó un estudio de la calidad del agua en dos sistemas lóticos, los arroyos Juan Blanco y Buñirigo (Argentina), sujetos a diferente uso del suelo (el primero se ubica dentro de una reserva de Biosfera de la UNESCO, mientras que el segundo en una zona agrícolo-ganadera e industrial). Se analizaron datos físico-químicos, parámetros estructurales del ensamble de macroinvertebrados y ensayos ecotoxicológicos. El objetivo fue identifi car el grado de deterioro en las áreas afectadas por efl uentes y los consiguientes efectos sobre la biota. Los resultados obtenidos permitieron establecer diferentes clases de calidad del agua dentro de la zona de estudio. De acuerdo a los índices aplicados la cuenca baja del arroyo Buñirigo fue caracterizada como moderadamente contaminada sobre la base de la pérdida de especies bentónicas sensibles o cambios en su abundancia. Del mismo modo, los ensayos ecotoxicológicos agudos demostraron que el agua de este sitio tuvo efectos letales sobre larvas de Caenis nemoralis (Ephemeroptera: Caenidae). Este punto de muestreo también evidenció características físico-químicas desfavorables para la biota, como alta conductividad y niveles de nutrientes, así como bajo contenido de oxígeno.

Ethanol-induced locomotor activity in adolescent rats and the relationship with ethanol-induced conditioned place preference and conditioned taste aversion Acevedo, María Belén; Nizhnikov, Michael; Spear, Norman E.; Molina, Juan Carlos; Pautassi, Ricardo Marcos Adolescent rats exhibit ethanol-induced locomotor activity (LMA), which is considered an index of ethanol's motivational properties likely to predict ethanol self-administration, but few studies have reported or correlated ethanol-induced LMA with conditioned place preference (CPP) by ethanol at this age. The present study assessed age-related differences in ethanol's motor stimulating effects and analyzed the association between ethanol-induced LMA and conventional measures of ethanol-induced reinforcement. Experiment 1 compared ethanol-induced LMA in adolescent and adult rats. Subsequent experiments analyzed ethanol-induced CPP and conditioned taste aversion (CTA) in adolescent rats evaluated for ethanol-induced LMA. Adolescent rats exhibit a robust LMA after high-dose ethanol. Ethanol-induced LMA was fairly similar across adolescents and adults. As expected, adolescents were sensitive to ethanol's aversive reinforcement, but they also exhibited CPP. These measures of ethanol reinforcement, however, were not related to ethanol-induced LMA. Spontaneous LMA in an open field was, however, negatively associated with ethanol-induced CTA.

Thin‐film β‐MoO3 Supported on α‐Fe2O3 as a Shell–Core Catalyst for the Selective Oxidation of Methanol to Formaldehyde Shir, Guojun; Franzke, Thomas; Sanchez, Miguel Dario; Xia, Wei; Weis, Frederik; Seipenbusch, Martin; Kasper, Gerhard; Muhler, Martin β‐MoO3/α‐Fe2O3 catalysts synthesized by chemical vapor deposition exhibit a uniform shell–core structure. The structure of the metastable β‐MoO3 film is retained even after calcination in air at 873 K, owing to strong Mo_O_Fe links at the interface. The shell–core β‐MoO3/α‐Fe2O3 catalysts are much more active than, and comparably selective to, the reference α‐MoO3 catalyst in the selective oxidation of methanol to formaldehyde.

Pollen morphology of the three subgenera of Alnus Leopold, Estella B.; Birkebak, Joshua; Reinink-Smith, Linda; Jayachandar, Anitha P.; Narvaez, Paula Liliana; Zaborac-Reed, Stephanie The three subgenera of alder (Alnusroman Clethropsis and Alnobetula) are taxonomically distinctive, but how does their pollen match up with their gross morphology? This study links pollen characters with the taxonomic divisions of the genus alder based on nrDNA ITS sequence data. The value of the study is in the breadth of the taxonomic coverage of the three subgenera, as the samples per species only range from 1 to 6. From 29 Alnus species, the authors studied pollen from 59 modern reference collections (prepared by acetolysis) and recorded the number and type of apertures (pores), thickness of the arci, pollen size and polar arci. Tallies of the number of pores on the pollen grains in a reference collection typically have a range of ± 1 or 2. Exceptions are presumed hybrid collections in Alnus rugosa with a range of ± 5, which have malformed pollen cells suggesting infertility. The presumed hybrids show a greater range of both pore number and size of pollen grains. The dominant pore number is a key feature that separates the subgenus Alnobetula (= Alnaster) from the other two subgenera by consistently having predominantly 5-, 6- or 7-pored pollen grains, while all other Alnus taxa sampled have pollen with predominantly 4- or 5-pored pollen. The dominant pore number is a consistent feature within the subgenus Alnobetula (10 species), but is inconsistent in 3 out of 16 species of the subgenus Alnus and within the subgenus Clethropsis (3 species). Thickenings of the pore lip, aspidate (protruding) and vestibulate pores are important features of Alnus pollen on a species level. Alnus-like pollen morphology occurs occasionally in certain other betulaceous genera (Betula and Carpinus). Differences in character or thickness of arci (band-like thickenings on the pollen wall between pores) tend to be somewhat consistent within a species and vary within subgenera. Two Alnobetula species in the Alnus viridis complex (Alnus crispa and Alnus sinuata) have arci that are weakly developed or appear as simple folds; walls are fragile and pores are typically less aspidate. Pollen sizes in different species overlap greatly, may be partly influenced by processing methods and do not seem to be generally helpful in characterizing species. Circular doughnut-shaped arci thickenings on the polar area of pollen grains are a common feature (16–40%) in two closely related East Asian taxa of subgenus Alnobetula with large pollen (‘Clade A’: Alnus firma and Alnus sieboldii). These ‘Clade A’ features have been reported from Miocene collections of Alnus pollen from Alaska, and support megafossil evidence in determining the biogeography of this group along the Pacific Rim in the Neogene. The Miocene appearance of subgenus Alnobetula megafossils in both Alaska and Japan can only have occurred via a Bering Land Bridge. This relation is now confirmed by Reinink-Smith's Miocene ‘Clade-A-type’ pollen data of Alaska. These taxa had Pacific Rim distributions, similar fruiting carposamaras and now correspond to a DNA ITS subgroup within Alnobetula. Depending on the geographic location with limited number of local alder species, certain Holocene identifications are possible based on pore structure and arci thickness, e.g. the Alnus crispa-type in eastern Canada and the Alnus sinuata-type in the Pacific northwest.

Environmental pesticide distribution in horticultural and floricultural periurban production units Querejeta, Giselle Andrea; Ramos, Laura Mabel; Flores, Andrea Pamela; Hughes, Enrique Alejandro; Zalts, Anita; Montserrat, Javier Marcelo The environmental pesticide distribution on non-target systems (soil, drift and agricultural plastics) during the application stage in small periurban production units (open field and greenhouses), was studied for various crops (tomato, lettuce, broccoli, strawberry and flowers) using different pesticides (endosulfan, procymidone, chlorothalonil, chlorpyrifos and deltamethrin). In all cases, soil was the most exposed non-target system. For greenhouses, a general pesticide distribution was found of approximately 2/3 for crop, 1/4 for soil and 1/20 for plastic, of the total amount applied. In horticultural open fields, although the distribution was very dependent on the crop size and type, soil was also the most exposed non-target subsystem. Pesticide drift seems not to be significant in these production units, whilst pesticide accumulation on agricultural plastics reached up to 45% of the total applied, for polyethylene mulching in strawberry fields.

Social inequality, environmental justice and water policy In Buenos Aires Merlinsky, Maria Gabriela; Fernandez Bouzo, Maria Soledad; Montera, Carolina; Tobias, Melina Privatisation of potable water and sanitation services in the Metropolitan Area of Buenos Aires during the 1990s led to important consequences in terms of investment and equality in the provision of the services. A new period was started in 2006 with the creation of the State-run company Agua y Saneamientos Argentinos SA, which became responsible for managing the provision of water and sewerage services in the region. Today, the company has to deal with the historical backwardness in terms of investment, the growing pressure from the population demanding access to the services, and the significant inequality of the covered area. On the other hand, due to the public impact of the court case regarding the sanitation of Matanza-Riachuelo basin, different territorial collectives have reformulated their demands for infrastructure works by including environmental terms. Besides, the Supreme Court of Justice has required the joint coordination of the works by Agua y Saneamientos Argentinos SA and the Authority of the basin. This means that water and sanitation management must answer to a great variety of actors and be able to operate in highly conflictive areas while meeting, at the same time, the environmental goals. This article describes the main actors involved in water and sanitation management in the Metropolitan Area of Buenos Aires and their approaches to the new plans of expansion of the services. The focus is to identify the opposing interests in terms of the distribution (which territories are the priority for the expansion of the water and sanitation networks); the implementation timetable (how to define the order of the works); and the emergence of different criteria of social and environmental justice. To this effect, we present an in-depth analysis of interviews to public officers, technicians and representatives of social organisations.

Characterization of novel Trichoderma spp. isolates as a search for effective biocontrollers of fungal diseases of economically important crops in Argentina Consolo, Verónica Fabiana; Monaco, Cecilia Ines; Cordo, Cristina Alicia; Salerno, Graciela Lidia Monoconidial cultures of 33 isolates of Trichoderma from Buenos Aires Province, Argentina were characterized on the basis of twenty eight morphological, physiological and biochemical features. All of them were screened for proteinase, endochitinase and â-1,3 glucanase activity. Universally primed PCR (UP-PCR) and inter-simple sequence repeat (ISSR) techniques were used to examine the genetic variability among isolates, which resulted in 127 bands for the total number of isolates. These results were subjected to numerical analysis revealing 20 haplotypes grouped in five clusters. The ability of Trichoderma isolates to antogonize soil-borne fungal plant pathogens using a dual culture assay was done against five fungal species: Alternaria sp., Bipolaris sorokiniana, Fusarium graminearum, F. solani, and Pyricularia oryzae. The highest inhibition values (85% RI) were obtained against B. sorokiniana and P. oryzae. Three isolates of T. harzianum named as FCCT2, FCCT3 and FCCT9 were capable of causing a high growth inhibition on four of the fungal species assayed, which was in agreement with their higher extracellular hydrolytic activity. Our results suggest that these isolates have the potential to be effective agents for biocontrol of cereal and tomato fungal pathogens.

Bioactive proteins from edible plants of Solanum genus. Ordóñez, Roxana Mabel; Sayago, Jorge Esteban; Zampini, Iris Catiana; Rodriguez, Ivana Fabiola; Cattaneo, Florencia; Isla, Maria Ines Bioactive proteins have been detected in manydifferent food sources. Beyond their nutritionalvalue many of them exhibit functional effects bothon the producing and on the consuming organisms.In recent years it has been recognized that proteinsprovide a rich source of biologically activepeptides. The genus Solanum has a great varietyof edible species that are an important source ofprotein. In this sense, some proteins might beinvolved in the response to wounding in plantdefense mechanisms like patatine and solamarineand snakin 1 and 2 isolated from S. tuberosumtubers and cyphomine isolated from S. betaceumfruits. They have shown in vitro inhibitory actionon hydrolases released by microorganisms involvedin cell wall degradation during the invasion process.They also have in vitro inhibitory effect onphytopathogenic microorganism growth for bothbacteria and fungi. It is thought that these proteinscould be part of the so-called pathogenesis-relatedproteins. As they are also present in edible tissue,these proteins have been studied from a functionalpoint of view. The purified proteins showedantioxidant or antiradical activities by a series ofin vitro tests, including DPPH, ABTS, hydroxyland superoxide radicals scavenging activityassays, anti-human low-density lipoproteinperoxidation tests, protections against hydroxylradical-mediated DNA damages, peroxynitritemediateddihydrorhodamine 123 oxidations andâ-carotene bleaching assay. A non mutagenic effectBioactive proteins from edible plants of Solanum genuswas observed in solamarine and cyphomine;solamarine also showed an antimutagenic effectagainst a direct mutagen. At present, an enzymatichydrolysis process on proteins is being carried outin order to obtain smaller molecules (peptides andfree amino acids) with improved nutritional qualityand safety. Three bioactive peptides (5A, 5C and6C) from potato protein hydrolysate fractions haverecently been isolated and showed antioxidantactivity. Hence, it would be possible to generatenew products and carry out alternative applicationsfor several agricultural and nutritional products.

Chemical Wear of Commercial Magnesia-Carbon Refractory Bricks in Air Camerucci, Maria Andrea; Galliano, Pablo German; Cavalieri, Ana Lia; Tomba Martinez, Analia Gladys In this work, the chemical degradation in air of different commercial MgO-C refractories used in the steelmaking industry was studied. Materials were characterized by mineralogical, microstructural, differential thermal and thermo-gravimetric analyses and measurements of density and porosity. Cylindrical samples were subjected to isothermal treatments at different temperatures and times in air and then, the weight loss and percentage of decarburized area were determined. Moreover, different surface conditionings (protective antioxidant paint and graphite powder muffle) were evaluated in regard to gas attack, and compared with non-conditioned specimens. The obtained results showed differences between the studied refractory materials according to the experimental conditions (temperature and time). At the low temperature regimen, pitch-based refractories exhibited the smallest chemical degradation whereas at high temperature, the material bonded with resin was the most resistant to oxygen chemical attack. The analysis of other phenomena related to microstructural changes helps to achieve a description of thermo-chemical processes occurring in the refractory samples during thermal treatments.