Evaluación de estructuras patrimoniales de hormigón armado afectadas por corrosión por cloruro en la provincia de Buenos Aires

La presencia de cloruro en el hormigón es un factor desencadenante del proceso de corrosión de armaduras. Diversas causas pueden concurrir para que se alcance el contenido límite de cloruro que despasiva al acero empotrado. Entre ellas las características del hormigón de recubrimiento, la agresividad del medio, la calidad constructiva, y los materiales empleados. En este trabajo se presenta una revisión de los parámetros ambientales, locales y de los materiales que deben tenerse en cuenta al momento de evaluar una estructura respecto a la corrosión por cloruro. Se incluyen metodologías y técnicas de evaluación, y su aplicación en estructuras de hormigón armado construidas en la Provincia de Buenos Aires, Argentina, durante el siglo XX y pertenecientes al patrimonio moderno. Se realizaron relevamientos in situ, mediciones in situ de parámetros de corrosión y extracción de muestras para su evaluación en laboratorio. Los resultados mostraron patologías por corrosión de armaduras vinculadas a la falta de mantenimiento preventivo, falta de control de materiales y ejecución durante la construcción y/o reparación de las estructuras analizadas. Como requerimiento para las reparaciones de este tipo de estructuras se incluyen especialmente las consideraciones del medio circundante.Tópico 6: Patrimonio Urbano de los siglos XVIII al XX. Técnicas de Limpieza y de Conservación

Influence of TiO2 nanometric filler on the behaviour of a composite membrane for applications in direct methanol fuel cells

Composite Nafion membranes containing various amounts of TiO2 (3 wt%, 5 wt% and 10 wt%) were investigated for operation in high temperature Direct Methanol Fuel Cells (DMFCs). Maximum power density of 350 mW cm -2 was achieved in the presence of oxygen feed at 145°C for the composite membranes containing 3-5 wt% TiO2; whereas, the maximum power density with air feed was about 210 mW cm-2. Moreover, an investigation of the influence of titanium oxide particle size on the electrochemical behaviour of the composite membranes for high temperature operation has been carried out. The DMFC performance increases as the mean particle size of the TiO2 filler decreases. This indicates an influence of the filler morphology on the electrochemical properties of the composite membranes. © J. New. Mat. Electrochem. Systems

Arcobacter spp. in raw milk from vending machines in Piedmont and occurrence of virulence genes in isolates

Arcobacter spp. has been recognized as an emerging foodborne pathogen and a hazard to human health. In the dairy chain, it has been isolated from different sources, nevertheless data on Arcobacter occurrence in raw milk provided by vending machines are few. This study aimed to identify potentially pathogenic Arcobacter spp. in raw milk intended for human consumption sold through vending machines located in Piedmont. In an 8-month period, 37 raw milk samples were collected from 24 dairy farms: 12 (32,4%) were collected directly in farm from bulk tank milk and 25 (67,6%) from vending machines. Eight (21,6%) out of the 37 milk samples and 7 (29,2%) out of the 24 dairy farms were positive for Arcobacter spp. by culture examination. Four (16%) out of the 25 samples from vending machines and 4 (33,3%) out of the 12 samples from bulk tank milk were positive. All 8 isolates were identified as A. butzleri both by MALDI-TOF MS and multiplex end-point PCR. According to the detection of virulence genes, a total of four Patho-types were highlighted: 5 isolates in P-type 1 and only one isolate for each of the P-types 2-3-4. A. butzleri isolates carrying encoding virulence factors genes were isolated from raw milk intended for human consumption: these findings strengthen the compulsory consumption after boiling as required by current legislation and suggest the need of enlarging the analytical investigations to other microorganisms not yet included in the food safety criteria

A novel synthetic approach of cerium oxide nanoparticles with improved biomedical activity

Cerium oxide nanoparticles (CNPs) are novel synthetic antioxidant agents proposed for treating oxidative stress-related diseases. The synthesis of high-quality CNPs for biomedical applications remains a challenging task. A major concern for a safe use of CNPs as pharmacological agents is their tendency to agglomerate. Herein we present a simple direct precipitation approach, exploiting ethylene glycol as synthesis co-factor, to synthesize at room temperature nanocrystalline sub-10 nm CNPs, followed by a surface silanization approach to improve nanoparticle dispersibility in biological fluids. CNPs were characterized using transmission electron microscopy (TEM) observations, X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (H-1-NMR) spectroscopy, dynamic light scattering (DLS) and zeta potential measurements. CNP redox activity was studied in abiotic systems using electron spin resonance (ESR) measurements, and in vitro on human cell models. In-situ silanization improved CNP colloidal stability, in comparison with non-functionalized particles, and allowed at the same time improving their original biological activity, yielding thus functionalized CNPs suitable for biomedical applications

Estudio e investigaciones realizadas en el LEMIT sobre materiales empleados en edificios históricos

Cuando se abordan problemas de restauración, reparación y conservación de edificios y construcciones de valor histórico se debe realizar, antes de iniciar las tareas de puesta en valor, un estudio integral de las causales que han provocado los deterioros. Esta situación es de primordial importancia, ya que si no se eliminan las causales, rápidamente reaparecen los signos externos de las alteraciones. Sin embargo, muchas de las alteraciones y/o deterioros de las construcciones de valor patrimonial y/o de los materiales que las constituyen se deben, con exclusividad, al pasaje del tiempo (vida en servicio de la construcción). Los materiales empleados en la construcción experimentan procesos de deterioro por reacciones físico, químicas o físico-químicas entre el material y los agentes agresivos o el originado por el crecimiento de microorganismos, en particular algas en sectores húmedos y sombríos y/o líquenes o plantas mayores como por ejemplo helechos. En este trabajo se presentan investigaciones y estudios de distintos materiales constituyentes de construcciones de valor patrimonial, en particular, se analizan ladrillos cerámicos comunes, mezclas de asiento, morteros internos y externos, tejas y materiales de revestimiento (cerámicos, pinturas y papel). Estos estudios fueron realizados para la caracterización de los materiales y/o para disponer de información técnica para su restauración o reemplazo. En todos los casos, se informan las técnicas de caracterización mecánica, física y química empleadas para su evaluación. En algunos casos, se realizan estudios de difracción de rayos X, microscopia electrónica de barrido (SEM), cortes petrográficos, análisis en lupa microscópica y microscopio petrográfico. Además, se han aplicado técnicas para determinar color y rugosidad

Comparative Safety of Originator and Biosimilar Epoetin Alfa Drugs: An Observational Prospective Multicenter Study

Background: Erythropoiesis-stimulating agents (ESAs) are biological molecules approved for the treatment of anemia associated with chronic renal failure. Biosimilars were licensed for use in Europe in 2007. Aim: This study aimed to compare the safety profile of biosimilars with respect to the reference product in a nephrology setting. Methods: A prospective study was conducted in four Italian regions between 1 October 2013 and 30 June 2015. The study population included patients aged 65 18 years undergoing hemodialysis and treated with epoetins as per the clinical practice of the participating centers. The two comparison cohorts included patients treated with either an originator or a biosimilar epoetin alfa. Each patient was followed up until occurrence of any safety outcome of interest (grouped into three major categories), switch to a different ESA product, transplant or peritoneal dialysis, death, or end of the study period, whichever came first. Results: Overall, 867 subjects were included in the study (originator: N = 423; biosimilar: N = 444). Biosimilar users were older than originator users (median age of 76 vs 64 years, respectively), more frequently affected by arrhythmia (29.3 vs 22.5%), and less frequently candidates for transplantation (3.8 vs 18.2%). Cox-regression analysis showed no increase in risk of safety outcomes in biosimilar users, even after adjusting for confounding factors: 1.0 (95% confidence interval [CI] 0.7\u20131.3) for any outcomes; 1.1 (95% CI 0.7\u20131.8) for problems related to dialysis device; 0.9 (95% CI 0.6\u20131.5) for cardio- and cerebro-vascular conditions; 0.9 (95% CI 0.6\u20131.5) for infections. Conclusion: This study confirms the comparable safety profiles of originator and biosimilar epoetin alfa drugs when used in patients receiving dialysis

Non-adenine based purines accelerate wound healing

Wound healing is a complex sequence of cellular and molecular processes that involves multiple cell types and biochemical mediators. Several growth factors have been identified that regulate tissue repair, including the neurotrophin nerve growth factor (NGF). As non-adenine based purines (NABPs) are known to promote cell proliferation and the release of growth factors, we investigated whether NABPs had an effect on wound healing. Full-thickness, excisional wound healing in healthy BALB/c mice was significantly accelerated by daily topical application of NABPs such as guanosine (50% closure by days 2.5′.8). Co-treatment of wounds with guanosine plus anti-NGF reversed the guanosine-promoted acceleration of wound healing, indicating that this effect of guanosine is mediated, at least in part, by NGF. Selective inhibitors of the NGF-inducible serine/threonine protein kinase (protein kinase N), such as 6-methylmercaptopurine riboside abolished the acceleration of wound healing caused by guanosine, confirming that activation of this enzyme is required for this effect of guanosine. Treatment of genetically diabetic BKS.Cg-m+/+lepr db mice, which display impaired wound healing, with guanosine led to accelerated healing of skin wounds (25% closure by days 2.8′.0). These results provide further confirmation that the NABP-mediated acceleration of cutaneous wound healing is mediated via an NGF-dependent mechanism. Thus, NABPs may offer an alternative and viable approach for the treatment of wounds in a clinical setting

Cerium Oxide Nanoparticles Protect Cardiac Progenitor Cells from Oxidative Stress

Cardiac progenitor cells (CPCs) are a promising autologous source of cells for cardiac regenerative medicine. However, CPC culture in vitro requires the presence of microenvironmental conditions (a complex array of bioactive substance concentration, mechanostructural factors, and physicochemical factors) closely mimicking the natural cell surrounding in vivo, including the capability to uphold reactive oxygen species (ROS) within physiological levels in vitro. Cerium oxide nanoparticles (nanoceria) are redox-active and could represent a potent tool to control the oxidative stress in isolated CPCs. Here, we report that 24 h exposure to 5, 10, and 50 !g/mL of nanoceria did not a!ect cell growth and function in cardiac progenitor cells, while being able to protect CPCs from H2O2-induced cytotoxicity for at least 7 days, indicating that nanoceria in an e!ective antioxidant. Therefore, these "ndings con"rm the great potential of nanoceria for controlling ROS-induced cell damage

Rough Fibrils Provide a Toughening Mechanism in Biological Fibers

Spider silk is a fascinating natural composite material. Its combination of strength and toughness is unrivalled in nature, and as a result, it has gained considerable interest from the medical, physics, and materials communities. Most of this attention has focused on the one to tens of nanometer scale: predominantly the primary (peptide sequences) and secondary (β sheets, helices, and amorphous domains) structure, with some insights into tertiary structure (the arrangement of these secondary structures) to describe the origins of the mechanical and biological performance. Starting with spider silk, and relating our findings to collagen fibrils, we describe toughening mechanisms at the hundreds of nanometer scale, namely, the fibril morphology and its consequences for mechanical behavior and the dissipation of energy. Under normal conditions, this morphology creates a nonslip fibril kinematics, restricting shearing between fibrils, yet allowing controlled local slipping under high shear stress, dissipating energy without bulk fracturing. This mechanism provides a relatively simple target for biomimicry and, thus, can potentially be used to increase fracture resistance in synthetic materials