The National University of the Littoral is a university in Argentina. It is based in Santa Fe, the capital of the province of the same name, and it has colleges and other academic facilities in Esperanza, Reconquista and Gálvez, also in Santa Fe Province. Wikipedia.
Gutkind G.O.,University of Buenos Aires |
Di Conza J.,National University of Litoral |
Power P.,University of Buenos Aires |
Radice M.,University of Buenos Aires
Current Pharmaceutical Design | Year: 2013
Early after the introduction of the first (narrow spectrum) penicillins into clinical use, penicillinase-producing staphylococci replaced (worldwide) the previously susceptible microorganisms. Similarly, the extensive use of broad-spectrum, orally administered β- lactams (like ampicillin, amoxicillin or cefalexin) provided a favorable scenario for the selection of gram-negative microorganisms producing broad spectrum β-lactamases almost 45 years ago. These microorganisms could be controlled by the introduction of the so called "extended spectrum cephalosporins". However, overuse of these drugs resulted, after a few years, in the emergence of extended-spectrum β-lactamases (ESBLs) through point mutations in the existing broad-spectrum β-lactamases, such as TEM and SHV enzymes. Overuse of extended-spectrum β-lactams also gave rise to chromosomal mutations in regulatory genes which resulted in the overproduction of chromosomal AmpC genes, and, in other regions of the world, in the explosive emergence of other ESBL families, like the CTX-Ms. Carbapenems remained active on microorganisms harboring these extended-spectrum β-lactamases, while both carbapenems and fourth generation cephalosporins remained active towards those with derepressed (or the more recent plasmidic) AmpCs. However, microorganisms countered this assault by the emergence of the so called carbapenemases (both serine- and metallo- enzymes) which, in some cases, are actually capable of hydrolyzing almost all β-lactams including the carbapenems. Although all these enzyme families (some of them represented by hundreds of members) are for sure pre-dating the antibiotic era in environmental and clinically significant microorganisms, it was the misuse of these antibiotics that drove their evolution. This paper describes in detail each major class of β-lactamase including epidemiology, genetic, and biochemical evaluations. © 2013 Bentham Science Publishers.
Sanchez Reinoso C.R.,National University of Litoral |
Sanchez Reinoso C.R.,Institute of Technological Development for the Chemical Industry INTEC |
Sanchez Reinoso C.R.,National University of Catamarca |
Milone D.H.,National University of Litoral |
Buitrago R.H.,Institute of Technological Development for the Chemical Industry INTEC
Applied Energy | Year: 2013
The increase in the power of photovoltaic systems involves a significant grow in the number of modules that make them up. The known problems caused by the shading are not usually taken into account in the design of a photovoltaic central away from urban environments. The aims of this study are to obtain a model for simulation of photovoltaic plants, representing the array under different conditions of dynamic shading, and to investigate its effects on configurations of modules array and converters. Performance measures are also discussed in order to find those most suitable for plants comparison in this context. Analyzing the efficiency of the maximum power point tracker and the inverter under different conditions of dynamic shading, using one or more inverters, a better performance is generally achieved by reducing the number of modules in series and by increasing the number of those in parallel. But the parallel connections are only suitable in certain conditions and the optimal number of parallels cannot be established trivially. The results show that the operating conditions determine the most efficient connection scheme with partial shading by using central inverter. Without using an optimization algorithm, we achieve results with central inverters not far from using microinverters. These results indicate that using the proposed simulator and an optimization algorithm, it can be optimize the complete system energy and take advantage of lower costs of central inverters for large photovoltaic plants. © 2012 Elsevier Ltd.
Guerrero M.,University of Bologna |
Ruther N.,Norwegian University of Science and Technology |
Szupiany R.N.,National University of Litoral
Flow Measurement and Instrumentation | Year: 2012
The aim of this paper is to validate a method of investigating the grain size distribution of suspended sediments using acoustic Doppler current profilers (ADCPs) and to compare different calibration strategies of the ADCP backscattering power, which can be correlated with the concentration of corresponding sediments. Over the last two decades, the methods for suspended sediment investigation using the backscattering power of ADCPs have been gaining increasing acceptance within the river engineering community. This acceptance is due to acoustic backscattering providing the opportunity to indirectly quantify suspended sediment by non-intrusive measurements with high temporal and spatial resolution. We have already presented the method using two ADCPs working at different frequencies (600 and 1200 kHz) on the same water column to profile the concentration and grain size in the Paraná River (Argentina). The present work, as a complement to the Paraná application, demonstrates the reliability of the method by a laboratory validation of monitored concentrations and known grain size distributions. The context of our research is introduced in a discussion of the topic of river sediment transport measurement using ADCPs. Then, the underwater acoustic physics is briefly presented with a focus on acoustic backscattering (ABS) methods for the estimation of suspended sediment grain size. The laboratory tests, which were conducted at the sediment tower-mixing facility using four different known distributions of sand in the range 50-700μm, are described in detail to demonstrate the reliability of the ABS methods and to justify the adopted experimental strategies to overcome undesired air bubble interference with the ABS due to injected sand. © 2011 Elsevier Ltd.
Antico A.,National University of Litoral |
Krohling D.M.,National University of Litoral
Geophysical Research Letters | Year: 2011
A link between climate and the motion of the Sun around the barycenter of the solar system has been suggested, mostly on the basis of interannual cycles observed in climatological data from the Northern Hemisphere. This study provides empirical evidence for a connection between this solar motion and discharge of the Paran River, which has the second largest drainage basin of South America. Solar motion is described here by the absolute value of the time derivative of solar angular momentum (τ). For the time period 1904-2008, the time evolution of both τ and river discharge is dominated by cycles with periods between 7 and 9 yr. Within this frequency band, a statistically significant anticorrelation is found between τ and river discharge with minima of τ coinciding with increased river discharge. Copyright 2011 by the American Geophysical Union.
Ojeda G.N.,National University of Litoral
Genetics and molecular research : GMR | Year: 2012
Sometimes, commercial products obtained from wild animals are sold as if they were from domestic animals and vice versa. At this point of the productive chain, legal control of possible wildlife products is difficult. Common in the commerce of northern Argentina, skins of two wild species, the carpincho and the collared peccary, look very similar to each other and to those of the domestic pig; it is extremely difficult to differentiate them after they have been tanned. Because there was no an adequate methodology to discriminate between leather of these three species, we developed a new methodology of DNA extraction from skin and leather. This new method involves digesting a leather sample using proteinase K, followed by precipitation of proteins with 5 M NaCl, cleaning with absolute isopropanol and DNA precipitation with 70% ethanol. DNA is hydrated in Tris-EDTA buffer. This protocol provided good-quality DNA suitable for analysis with molecular markers. This new protocol has potential for use in identifying leather products of these species using molecular markers based on RAPDs.
Escandar G.M.,National University of Rosario |
Goicoechea H.C.,National University of Litoral |
Munoz de la Pena A.,University of Extremadura |
Olivieri A.C.,National University of Rosario
Analytica Chimica Acta | Year: 2014
An introduction to multi-way calibration based on second- and higher-order data generation and processing is provided, with emphasis on practical experimental aspects. After a discussion concerning a proper nomenclature scheme, a suitable classification of the obtainable data, and the general features of the available algorithms and their underlying models, a series of examples is discussed in detail, with the purpose of illustrating the great potentiality of the field for the analytical community. Emphasis is directed toward the most popular multi-way data, i.e., second-order or matrix data, which can be conveniently measured in a variety of instruments. Third-order data are being increasingly studied and are also discussed, along with the less explored field of fourth-order data. The estimation of figures of merit, which analysts need to report during method development, is now sufficiently mature to be provided for the general audience. © 2013 Elsevier B.V.
Guerrero M.,University of Bologna |
Szupiany R.N.,National University of Litoral |
Latosinski F.,National University of Litoral
Journal of Hydraulic Research | Year: 2013
A method of using two acoustic Doppler current profilers operating at different frequencies and employed at the same measuring vertical to sample a profile of suspended sediment concentration has been previously applied in the Parana River (Argentina) but has not been validated by direct sediment samples. The present work fills this gap by reporting new field data and comparing them with acoustically inferred sediment concentrations. The agreement between directly measured sediment concentrations and grain sizes with corresponding estimates from an employed backscatter model was found to be good (squared correlation coefficients are 0.9 and 0.8, and mean deviations are 14 and 6%, respectively). The interrelations between flow velocity and suspended sediment concentration at fixed locations and in a moving mode along a river cross-section have been also investigated. Observed events of bed sediment re-suspension were found to be highly correlated with fluctuations of the vertical flow velocity, with a 100-150s quasi-periodicity. The size of re-suspension plumes was increasing from the channel thalweg to the low-submerged bar areas. © 2013 © 2013 International Association for Hydro-Environment Engineering and Research.
Orihuela S.,National University of Litoral
Cartographic Journal | Year: 2016
The Lagrange projection represents conformally the terrestrial globe within a circle. This is achieved by compressing the latitude and longitude and by applying the new coordinates into the equatorial stereographic projection. The same concept can be generalized to any conformal projection, although the application of this technique to other analytical functions is less known. In this work, the general Lambert–Lagrange projection formula is proposed and the application of the modified coordinates is discussed on projections: stereographic, conformal conic and Gauss–Schreiber. In general, the results are merely a curiosity, except for the case of Gauss–Schreiber, where the use of coordinates with altered scale can be applied in the optimization of conformal projections. © 2016, © The British Cartographic Society 2016.
D'Alessandro M.E.,National University of Litoral |
Chicco A.,National University of Litoral |
Lombardo Y.B.,National University of Litoral
Prostaglandins Leukotrienes and Essential Fatty Acids | Year: 2013
The role and underlying mechanisms by which n-3 polyunsaturated fatty acids (PUFA) prevent/reverse SRD-induced insulin resistance (IR) in the muscle are not completely understood. Therefore, we examined: triglyceride, diacylglycerol, PKCθ, Glut-4, enzymatic hexokinase activity, IRS-1 protein mass level, and fatty acid composition of muscle phospholipids. Rats were fed a SRD during 6 months. Thereafter, half the animals continued with SRD up to 8 months; the other half was fed a SRD in which CO (8%. wt/wt) was replaced by FO (7%+1% CO) for 2 months. Results were compared with those obtained in rats fed a control diet (CD). In SRD-fed rats, FO oil normalized/improved lipid storage and PKCθ protein mass level. Effects of insulin were comparable with those of CD-fed rats. FO reversed impaired glucose phosphorylation, IRS-1, and, under insulin stimulation, Glut-4 protein mass level. FO normalized insulin resistance and increased n-3 PUFAs in muscle phospholipids. © 2012 Elsevier Ltd.
Rossi A.S.,National University of Litoral
The British journal of nutrition | Year: 2013
The present study analyses the effect of dietary chia seed rich in n-3 α-linolenic acid on the mechanisms underlying dyslipidaemia and liver steatosis developed in rats fed a sucrose-rich diet (SRD) for either 3 weeks or 5 months. The key hepatic enzyme activities such as fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), glucose-6-phosphate dehydrogenase (G-6-PDH), carnitine palmitoyltransferase-1 (CPT-1) and fatty acid oxidase (FAO) involved in lipid metabolism and the protein mass levels of sterol regulatory element-binding protein-1 (SREBP-1) and PPARα were studied. (1) For 3 weeks, Wistar rats were fed either a SRD with 11 % of maize oil (MO) as dietary fat or a SRD in which chia seed replaced MO (SRD+Chia). (2) A second group of rats were fed a SRD for 3 months. Afterwards, half the rats continued with the SRD while for the other half, MO was replaced by chia for 2 months (SRD+Chia). In a control group, maize starch replaced sucrose. Liver TAG and the aforementioned parameters were analysed in all groups. The replacement of MO by chia in the SRD prevented (3 weeks) or improved/normalised (5 months) increases in dyslipidaemia, liver TAG, FAS, ACC and G-6-PDH activities, and increased FAO and CPT-1 activities. Protein levels of PPARα increased, and the increased mature form of SREBP-1 protein levels in the SRD was normalised by chia in both protocols (1 and 2). The present study provides new data regarding some key mechanisms related to the fate of hepatic fatty acid metabolism that seem to be involved in the effect of dietary chia seed in preventing and normalising/improving dyslipidaemia and liver steatosis in an insulin-resistant rat model.