The National University of Cuyo is the largest center of higher education in the province of Mendoza, Argentina.As of 2005, the university had 12 academic schools in the city of Mendoza and a delegation in the city of San Rafael , in addition to the Balseiro Institute, which is the most developed institute of Physics research in Argentina, located in the city of San Carlos de Bariloche . It includes the University Technological Institute which offers technical education in four other cities in Mendoza province. Moreover, UNCuyo is also devoted to improving education due to having 7 other buildings working as High Schools: C.U.C. Escuela de Comercio Martín Zapata Liceo Agrícola Escuela del Magisterio Colegio de Gral. Alvear. D.A.D Escuela Carmen Vera Arenas Wikipedia.
News Article | March 4, 2016
One of the main reasons for limiting the operating lifetimes of nuclear reactors is that metals exposed to the strong radiation environment near the reactor core become porous and brittle, which can lead to cracking and failure. Now, a team of researchers at MIT and elsewhere has found that, at least in some reactors, adding a tiny quantity of carbon nanotubes to the metal can dramatically slow this breakdown process. For now, the method has only proved effective for aluminum, which limits its applications to the lower-temperature environments found in research reactors. But the team says the method may also be usable in the higher-temperature alloys used in commercial reactors. The findings are described in the journal Nano Energy, in a paper by MIT Professor Ju Li, postdocs Kang Pyo So and Mingda Li, research scientist Akihiro Kushima, and 10 others at MIT, Texas A&M University, and universities in South Korea, Chile, and Argentina. Aluminum is currently used in not only research reactor components but also nuclear batteries and spacecraft, and it has been proposed as material for storage containers for nuclear waste. So, improving its operating lifetime could have significant benefits, says Ju Li, who is the Battelle Energy Alliance Professor of Nuclear Science and Engineering and a professor of materials science and engineering. The metal with carbon nanotubes uniformly dispersed inside “is designed to mitigate radiation damage” for long periods without degrading, says Kang Pyo So. Helium from radiation transmutation takes up residence inside metals and causes the material to become riddled with tiny bubbles along grain boundaries and progressively more brittle, the researchers explain. The nanotubes, despite only making up a small fraction of the volume — less than 2 percent — can form a percolating, one-dimensional transport network, to provide pathways for the helium to leak back out instead of being trapped within the metal, where it could continue to do damage. Testing showed that after exposure to radiation, the carbon nanotubes within the metal can be chemically altered to carbides, but they still retain their slender shape, “almost like insects trapped in amber,” Ju Li says. “It’s quite amazing — you don’t see a blob; they retain their morphology. It’s still one-dimensional.” The huge total interfacial area of these 1-D nanostructures provides a way for radiation-induced point defects to recombine in the metal, alleviating a process that also leads to embrittlement. The researchers showed that the 1-D structure was able to survive up to 70 DPA of radiation damage. (DPA is a unit that refers to how many times, on average, every atom in the crystal lattice is knocked out of its site by radiation, so 70 DPA means a lot of radiation damage.) After radiation exposure, Ju Li says, “we see pores in the control sample, but no pores” in the new material, “and mechanical data shows it has much less embrittlement.” For a given amount of exposure to radiation, the tests have shown the amount of embrittlement is reduced about five to tenfold. The new material needs only tiny quantities of carbon nanotubes (CNTs) — about 1 percent by weight added to the metal — and these are inexpensive to produce and process, the team says. The composite can be manufactured at low cost by common industrial methods and is already being produced by the ton by manufacturers in Korea, for the automotive industry. Even before exposure to radiation, the addition of this small amount of nanotubes improves the strength of the material by 50 percent and also improves its tensile ductility — its ability to deform without breaking — the team says. “This is a proof of principle,” says Kang Pyo So. While the material used for testing was aluminum, the team plans to run similar tests with zirconium, a metal widely used for high-temperature reactor applications such as the cladding of nuclear fuel pellets. “We think this is a generic property of metal-CNT systems,” he says. “This is a development of considerable significance for nuclear materials science, where composites — particularly oxide dispersion-strengthened steels — have long been considered promising candidate materials for applications involving high temperature and high irradiation dose,” says Sergei Dudarev, a professor of materials science at Oxford University in the U.K., who was not involved in this work. Dudarev adds that this new composite material “proves remarkably stable under prolonged irradiation, indicating that the material is able to self-recover and partially retain its original properties after exposure to high irradiation dose at room temperature. The fact that the new material can be produced at relatively low cost is also an advantage.” Sergei Kucheyev, a physicist at the Lawrence Livermore National Laboratory who also was not involved in this research, says, “These results could have important technological implications. They also point to our still-limited understanding of the physics of radiation defects at interfaces in technologically relevant regimes.” The team also included researchers Sangtae Kim, Yang Yang, and Ziqiang Wang at MIT; Di Chen and Shao Lin at Texas A&M University; Jong Gil Park and Young Hee Lee at the Institute for Basic Science in South Korea; Rafael Gonzalez and Miguel Kiwi at the University of Chile; and Eduardo Bringa at the National University of Cuyo, in Argentina. The work was supported by the U.S. Department of Energy and the National Research Foundation of Korea.
Inis Biotech Llc, Conicet and National University of Cuyo | Date: 2015-04-07
Process for obtaining lithium compounds and intermediate compounds, comprising the following steps: a) contacting aluminosilicate particles, for example -spodumene, with at least one fluorine compound, for example HF, NaF or others; b) stirring the mixture increasing the temperature until reaching an appropriate temperature; c) carrying out at least a precipitation and filtration process of the mixture of step b), and, d) recovering the lithium compound. The process may comprise using HF at a concentration between 5 and 30% v/v or NaF at a concentration between 5 and 30% w/v; a solid/liquid ratio of step a) between 0.9 and 14.4% w/v; a particle size of between 29 and 200 m. The final lithium product of the process may be lithium carbonate or lithium fluoride.
Mestre M.B.,National University of Cuyo |
Colombo M.I.,National University of Cuyo
PLoS Pathogens | Year: 2012
Staphylococcus aureus is a microorganism that causes serious diseases in the human being. This microorganism is able to escape the phagolysosomal pathway, increasing intracellular bacterial survival and killing the eukaryotic host cell to spread the infection. One of the key features of S. aureus infection is the production of a series of virulence factors, including secreted enzymes and toxins. We have shown that the pore-forming toxin α-hemolysin (Hla) is the S. aureus-secreted factor responsible for the activation of the autophagic pathway and that this response occurs through a PI3K/Beclin1-independent form. In the present report we demonstrate that cAMP has a key role in the regulation of this autophagic response. Our results indicate that cAMP is able to inhibit the autophagy induced by Hla and that PKA, the classical cAMP effector, does not participate in this regulation. We present evidence that EPAC and Rap2b, through calpain activation, are the proteins involved in the regulation of Hla-induced autophagy. Similar results were obtained in cells infected with different S. aureus strains. Interestingly, in this report we show, for the first time to our knowledge, that both EPAC and Rap2b are recruited to the S. aureus-containing phagosome. We believe that our findings have important implications in understanding innate immune processes involved in intracellular pathogen invasion of the host cell. © 2012 Mestre, Colombo.
Vazquez-Prieto M.A.,National University of Cuyo |
Miatello R.M.,National University of Cuyo
Molecular Aspects of Medicine | Year: 2010
Epidemiological studies have shown an inverse relationship between consumption of fruits and vegetables and the risk of cardiovascular disease. Phytochemicals are non-nutritional chemical compounds found in small quantities in fruits and vegetables with known health benefits. Among them, organosulfides are present mainly in garlic and onion characterized by their antioxidant and anti-inflammatory properties, and isothiocyanates in cruciferous vegetables have anticarcinogenic effects in experimental models. In this review, we are focusing on the main biological studies regarding the beneficial effect of organosulfur compounds on their protection against cardiovascular disease. © 2010 Elsevier Ltd.
Tomes C.N.,National University of Cuyo
Biochemical Journal | Year: 2015
Exocytosis is a highly regulated process that consists of multiple functionally, kinetically and/or morphologically definable stages such as recruitment, targeting, tethering and docking of secretory vesicles with the plasma membrane, priming of the fusion machinery and calcium-triggered membrane fusion. After fusion, the membrane around the secretory vesicle is incorporated into the plasma membrane and the granule releases its contents. The proteins involved in these processes belong to several highly conserved families: Rab GTPases, SNAREs (soluble NSF-attachment protein receptors), α-SNAP (α-NSF attachment protein), NSF (N-ethylmaleimide-sensitive factor), Munc13 and -18, complexins and synaptotagmins. In the present article, the molecules of exocytosis are reviewed, using human sperm as a model system. Sperm exocytosis is driven by isoforms of the same proteinaceous fusion machinery mentioned above, with their functions orchestrated in a hierarchically organized and unidirectional signalling cascade. In addition to the universal exocytosis regulator calcium, this cascade includes other second messengers such as diacylglycerol, inositol 1,4,5-trisphosphate and cAMP, as well as the enzymes that synthesize them and their target proteins. Of special interest is the cAMP-binding protein Epac (exchange protein directly activated by cAMP) due in part to its enzymatic activity towards Rap. The activation of Epac and Rap leads to a highly localized calcium signal which, together with assembly of the SNARE complex, governs the final stages of exocytosis. The source of this releasable calcium is the secretory granule itself. © The Authors Journal compilation © 2015 Biochemical Society.
Felix L.A.,National University of Cuyo
Nanotechnology | Year: 2012
The transport properties of ultra-thin SrTiO(3) (STO) layers grown over YBa(2)Cu(3)O(7) electrodes were studied by conductive atomic force microscopy at the nano-scale. A very good control of the barrier thickness was achieved during the deposition process. A phenomenological approach was used to obtain critical parameters regarding the structural and electrical properties of the system. The STO layers present an energy barrier of 0.9 eV and an attenuation length of 0.23 nm, indicating very good insulating properties for the development of high-quality Josephson junctions.
Vazquez C.L.,National University of Cuyo |
Colombo M.I.,National University of Cuyo
Cell Death and Differentiation | Year: 2010
Coxiella burnetii is the etiological agent of the human disease, Q fever, and is an obligate intracellular bacterium that invades and multiplies in a vacuole with lysosomal characteristics. We have previously shown that Coxiella interacts with the autophagic pathway as a strategy for its survival and replication. In addition, recent studies have shown that Coxiella exerts anti-apoptotic activity to maintain the host cell viability, thus generating a persistent infection. In the present report, we have explored the role of Beclin 1 and Bcl-2 in C. burnetii infection to elucidate how this bacterium modulates autophagy and apoptosis to its own benefit. Beclin 1, a Bcl-2 interacting protein, is required for autophagy. In this study, we show that Beclin 1 is recruited to the Coxiella-membrane vacuole, favoring its development and bacterial replication. In contrast, the anti-apoptotic protein Bcl-2 alters the normal development of the Coxiella-replicative compartment, in spite of also being recruited to the vacuole membrane. Furthermore, both vacuole development and the anti-apoptotic effect of C. burnetii are affected by Beclin 1 depletion and by the expression of a Beclin 1 mutant defective in Bcl-2 binding. Overall, these findings indicate that C. burnetii infection modulates autophagy and apoptotic pathways through Beclin 1/Bcl-2 interplay to establish a successful infection in the host cell. © 2010 Macmillan Publishers Limited. All rights reserved.
Renna N.F.,National University of Cuyo
Mediators of inflammation | Year: 2013
The objective of this work was to demonstrate the role of COX-2 enzyme at the vascular in experimental model of metabolic syndrome. SHR male WKY rats were employed; they were distributed in 8 groups (n = 8 each): control (W); W + L: WKY rats receiving 20 mg/kg of lumiracoxib by intraesophageal administration; SHR; SHR + L: SHR + 20 mg/kg of lumiracoxib by intraesophageal administration; Fructose-Fed Rats (FFR): WKY rats receiving 10% (w/v) fructose solution in drinking water during all 12 weeks; FFR + L: FFR + 20 mg/kg of lumiracoxib by intraesophageal administration; Fructose-Fed Hypertensive Rats (FFHR): SHR receiving 10% (w/v) fructose solution in drinking water during all 12 weeks; and FFHR + L: FFHR + 20 mg/kg of lumiracoxib by intraesophageal administration. Metabolic variables, blood pressure, morphometric variables, and oxidative stress variables were evaluated; also MMP-2 and MMP-9 (collagenases), VCAM-1, and NF- κ B by Westernblot or IFI were evaluated. FFHR presented all variables of metabolic syndrome; there was also an increase in oxidative stress variables; vascular remodeling and left ventricular hypertrophy were evidenced along with a significant increase in the expression of the mentioned proinflammatory molecules and increased activity and expression of collagenase. Lumiracoxib was able to reverse vascular remodeling changes and inflammation, demonstrating the involvement of COX-2 in the pathophysiology of vascular remodeling in this experimental model.
Ambrosini D.,National University of Cuyo
Engineering Structures | Year: 2010
Regularly, new theories and approaches about thin walled beams are presented in the literature and different comparisons are performed between them. However, in most cases, it is notable the lack of experimental data, particularly about nonsymmetrical thin walled beams, which are essential to compare the results in order to obtain reliable conclusions about the accuracy and applicability of these theories. In this paper, an experimental study about natural frequencies of doubly unsymmetrical thin walled and open cross-section beams is presented. Then, the main objective of this paper is to provide experimental data that can be used for checking the accuracy and reliability of different theories and approaches.Moreover, a theoretical-numerical model developed by the author, which is based on Vlasov's theory of thin walled beams, is applied to the actual tested beams. The results obtained with this theory are compared with the experimental ones and with those obtained with a FEM code. © 2010 Elsevier Ltd.
Curadelli O.,National University of Cuyo
Journal of Constructional Steel Research | Year: 2013
Seismic performance of cylindrical liquid storage tanks base-isolated by bilinear bearings is investigated. The paper displays a stochastic parametrical study in which three design parameters, namely isolation period, yield strength and viscous damping ratio, characterizing the isolation system are taken into consideration. The earthquake excitation, modeled as a stationary random process, is characterized by a power spectral density function calculated via a compatible seismic design spectrum. The stochastic response of the base-isolated cylindrical tanks is obtained by the convolution between the frequency response function of the system and the input power spectrum. To determine effective damping and stiffness coefficients corresponding to the equivalent linear system a statistical linearization scheme was used. For the purpose of evaluating the seismic behavior under different conditions, two liquid levels (aspect ratios) and soil types (soft and stiff soil) were considered. Thus, the study demonstrates the influence of each characteristic parameter of the isolation system and soil conditions on the response of cylindrical base-isolated tanks and principally allows visualizing the seismic performance that can be achieved through the selection of those parameters under certain soil conditions. Further, it is confirmed that soft soil conditions amplify the overall response of the system specially the base and sloshing displacements, as well as the normalized base shear to a lesser extent. © 2013 Elsevier Ltd.