Uso de analogías adecuadas como recurso didáctico para la comprensión de los fenómenos electroquímicos en el nivel universitario inicial

In this paper, we propose a complementary strategy to introduce electrochemical cells in introductory courses of chemistry. Frequently some of the concepts related to electrochemical processes, such as electric work, reversible and irreversible changes, maximum work and differences and similarities between galvanic and electrolytic cells among others, are poorly developed in this kind of courses. We propose, for the introductory treatment of these concepts, an analogy between isothermal expansion of a perfect gas and an electrochemical process. The analogy is qualitatively and quantitatively discussed

Chemical evolution of 26^{26}Al and 60^{60}Fe in the Milky Way

We present theoretical mass estimates of $^{26}$Al and $^{60}$Fe throughout the Galaxy, performed with a numerical chemical evolution model including detailed nucleosynthesis prescriptions for both stable and radioactive nuclides. We compared the results for several sets of stellar yields taken from the literature, either for massive, low and intermediate mass stars, nova systems (only for $^{26}$Al) and supernovae Type Ia, and then computed the total masses of $^{26}$Al and $^{60}$Fe in the Galaxy. In particular, we have studied the bulge and the disc of the Galaxy in a galactocentric radius range between 0 and 22 kpc. We have assumed that the bulge (between 0 and 2 kpc) evolved quickly suffering a strong burst of star formation, while the disc formed more slowly and inside-out, in agreement with previous works, which reproduced the majority of observational constraints. We have compared our results with the $^{26}$Al mass observed by the $\gamma$-ray surveys COMPTEL and INTEGRAL, in order to select the best model. Concerning $^{60}$Fe, for which we do not have any observed mass value, we have just predicted its mass to provide a theoretical prediction to be confirmed or disproved by future observations. We have found that low and intermediate mass stars as well as Type Ia supernovae contribute negligibly to the two isotopes, while massive stars are the dominant source. The contribution from novae is, however, necessary to reproduce the observed mass of $^{26}$Al, and this is a new result. Our best model predicts $2.12$ M$_{\odot}$ of $^{26}$Al, in agreement with observations, while for $^{60}$Fe our best mass estimate is around $\sim 1.05$ M$_{\odot}$. We have also predicted the present rate of injection of $^{26}$Al and $^{60}$Fe in the Galaxy and compared it with previous results, and we have predicted a larger present time injection rate along the disc, relative to previous works.Comment: 10 pages, 6 figure

Numerical Modelling and Simulation Optimization of Geothermal Reservoirs Using the Tough2 Family of Codes

In order to improve the reservoir engineering activities and, in particular, to optimize numerical modelling and simulation of geothermal reservoirs using the TOUGH family of codes, it has been decided to use the software T2Well for the interpretation of well-tests, coupling T2Well with the equation of state module EWASG, which describes the typical thermodynamic condition in high enthalpy geothermal reservoirs. T2Well-EWASG has been coupled and tested through the typical process of verification and validation. The application of T2Well-EWASG for the interpretation of well-tests related to the slim hole WW-01 drilled in the Wotten Waven Field (Commonwealth of Dominica) proves that it can be used as a tool for integrated interpretation of surface and downhole measurements collected during the performance of production tests in geothermal wells. The strength of this tool is that it allows to reduce the different possible solutions (in terms of reservoir characterization) within an acceptable error, by allowing the interpretation of surface and downhole measurements in conjunction, instead of separately. From this point of view T2Well-EWASG can effectively be used as a tool which allows an improvement of reservoir engineering activities. Finally, the huge amount of data managed during these activities has permitted to test and project the improvement of pre- and post- processing tools specific for TOUGH2 created by the geothermal research group of DICAM. In particular, the pre- and post-processing tools have been validated with a case study dealing with the migration of non-condensable gases in deep sedimentary formation

Exploring genetic diversity in an Italian horse native breed to develop strategies for preservation and management

Genetic diversity is a key factor for both adaptation and response to selection. The loss of genetic diversity causes a decrease in individual fitness, and it has a dramatically negative effect on population lifespan in the long term. This study aimed at exploring the genetic diversity at pedigree level of the Bardigiano horse breed, which is a native breed from Italy shaped for living in rural areas. In 1977, the Bardigiano studbook was founded to preserve the breed and for improving its use for riding and draft purposes. Pedigree data contained 9,469 horses, of which 3,416 were alive. Demographic and genetic parameters were estimated on subpopulations to evaluate potential genetic diversity differences among breeding and nonbreeding animals, and animals showing different breeding values (EBVs) for an index combining 18 conformation traits. Throughout the studied period, inbreeding steadily increased, reaching in the last birth year cohort a mean value equal to 0.10. The rate of inbreeding per generation, assuming a mean generation interval of 8.74 years, was equal to 1.64%. Moreover, significant differences on both average relatedness and inbreeding among horses with high and low EBVs were shown. Our study unravelled the state of genetic diversity in the Bardigiano breed, highlighting that breeding strategies for optimizing the contribution of breeding animals in the coming generations are needed to ensure long‐term survival of the Bardigiano horse breed

TOUGH2Viewer tutorial

TOUGH2Viewer is a Java program capable of displaying unstructured (Voronoi complying) grids, locally refined and structured grids (complying with the MESHMAKER iTOUGH2 format). In particular, TOUGH2Viewer allows to navigate through a 3D grid compatible with the iTOUGH2 data file format and see: (1) the thermodynamic variables and the material (namely, petrophysical properties) of each block; (2) maps of isovalues (2D) of all thermodynamic variables; (3) isosurfaces (3D) of all thermodynamic variables; (4) flows of mass and heat between blocks; (5) spatial profiles of thermodynamic variables, of a selected set of blocks, long a Cartesian directions; (6) time plot of thermodynamic variables of a selected block. All commands to manage a 3D visualization (zooming, pan, rotations) are CAD complying

Genetic Diversity and Signatures of Selection in a Native Italian Horse Breed Based on SNP Data

Horses are nowadays mainly used for sport and leisure activities, and several local breeds, traditionally used in agriculture, have been exposed to a dramatic loss in population size and genetic diversity. The loss of genetic diversity negatively impacts individual fitness and reduces the potential long-term survivability of a breed. Recent advances in molecular biology and bioinformatics have allowed researchers to explore biodiversity one step further. This study aimed to evaluate the loss of genetic variability and identify genomic regions under selection pressure in the Bardigiano breed based on GGP Equine70k SNP data. The effective population size based on Linkage Disequilibrium (Ne) was equal to 39 horses, and it showed a decline over time. The average inbreeding based on runs of homozygosity (ROH) was equal to 0.17 (SD = 0.03). The majority of the ROH were relatively short (91% were ≤ 2Mbp long), highlighting the occurrence of older inbreeding, rather than a more recent occurrence. A total of eight ROH islands, shared among more than 70% of the Bardigiano horses, were found. Four of them mapped to known quantitative trait loci related to morphological traits (e.g., body size and coat color) and disease susceptibility. This study provided the first genome-wide scan of genetic diversity and selection signatures in an Italian native horse breed

Chemical evolution of 26Al and 60Fe in the Milky Way

We present theoretical mass estimates of 26Al and 60Fe throughout the Galaxy, performed with a numerical chemical evolution model including detailed nucleosynthesis prescriptions for stable and radioactive nuclides. We compared the results for several sets of stellar yields taken from the literature, for massive, low and intermediate mass stars, nova systems (only for 26Al) and supernovae Type Ia. We then computed the total masses of 26Al and 60Fe in the Galaxy. We studied the bulge and the disc of the Galaxy in a Galactocentric radius range of 0-22 kpc. We assumed that the bulge region (within 2 kpc) evolved quickly suffering a strong star formation burst, while the disc formed more slowly and inside-out. We compared our results with the 26Al mass observed by the gamma-ray surveys COMPTEL and INTEGRAL to select the best model. Concerning 60Fe, we do not have any observed mass value so we just performed a theoretical prediction for future observations. In conclusion, low, intermediate mass stars, and Type Ia supernovae contribute negligibly to the two isotopes, while massive stars are the dominant source. The nova contribution is, however, necessary to reproduce the observations of 26Al. Our best model predicts 2.12 M⊙ of 26Al, in agreement with observations, while for 60Fe our best mass estimate is ~1.05 M⊙. We also predicted the present injection rate of 26Al and 60Fe in the Galaxy and compared it with previous results, and we found a larger present time injection rate along the disc

Addition of aromatic nucleophiles to a C=N double bond of 1,2,5-thiadiazole 1,1-dioxide

A new synthesis of 3,4-diphenyl-4-aryl-1,2,5-thiadiazolines 1,1-dioxide through the addition of aromatic derivatives to 1,2,5-thiadiazole 1,1-dioxide is presented. Anhydrous AlCl3 is used as catalyst.Facultad de Ciencias Exacta

Controlling Dynamic DNA Reactions at the Surface of Single-Walled Carbon Nanotube Electrodes to Design Hybridization Platforms with a Specific Amperometric Readout

: Carbon nanotube (CNT)-based electrodes are cheap, highly performing, and robust platforms for the fabrication of electrochemical sensors. Engineering programmable DNA nanotechnologies on the CNT surface can support the construction of new electrochemical DNA sensors providing an amperometric output in response to biomolecular recognition. This is a significant challenge, since it requires gaining control of specific hybridization processes and functional DNA systems at the interface, while limiting DNA physisorption on the electrode surface, which contributes to nonspecific signal. In this study, we provide design rules to program dynamic DNA structures at the surface of single-walled carbon nanotubes electrodes, showing that specific DNA interactions can be monitored through measurement of the current signal provided by redox-tagged DNA strands. We propose the use of pyrene as a backfilling agent to reduce nonspecific adsorption of reporter DNA strands and demonstrate the controlled formation of DNA duplexes on the electrode surface, which we then apply in the design and conduction of programmable DNA strand displacement reactions. Expanding on this aspect, we report the development of novel amperometric hybridization platforms based on artificial DNA structures templated by the small molecule melamine. These platforms enable dynamic strand exchange reactions orthogonal to conventional toehold-mediated strand displacement and may support new strategies in electrochemical sensing of biomolecular targets, combining the physicochemical properties of nanostructured carbon-based materials with programmable nucleic acid hybridization

Evidência de infecção intra-uterina por Mycobacterium avium subsp. paratuberculosis usando Multiple-Locus Variable-number tandem-repeat Analysis:: primeiro relato na Argentina

Uma novilha prenha em estado clínico avançado de paratuberculose foi observada em um rebanho bovino na Argentina. O animal foi eutanasiado e foram colhidas amostras dos seus órgãos e dos órgãos feto as quais foram cultivadas para bacteriologia em meio específico. Os tecidos foram examinados por histopatologia (coloração de hematoxilina-eosina e Ziehl-Neelsen). Na histopatologia das amostras colhidas da novilha foram observadas lesões compatíveis com paratuberculose e a coloração de Ziehl-Neelsen revelou a presença de bacilos álcool-ácido resistentes, nos tecidos fetais não foram observadas lesões, porém a coloração de Ziehl-Neelsen revelou a presença de bacilos álcool-ácido resistentes. Após o crescimento em meio específico, as colônias foram positivas para o teste IS900-PCR nos tecidos de ambos, vaca e feto, confirmando a presença de Mycobacterium avium subsp. paratuberculosis. Por fim, os isolados foram tipados por Multiple-Locus Variable-number tandem-repeat Analysis, confirmando a relação epidemiológicaentre eles. Este estudo relata a primeira detecção de Mycobacterium avium subsp. paratuberculosis na Argentina em que houve o compartilhamento de um tipo idêntico de MLVA em uma vaca prenhe e no seu feto. Os resultados deste estudo são consistentes com relatos anteriores e destacam a transmissão intra-uterina de Mycobacterium avium subsp. paratuberculosis como importante fonte de infecção nos rebanhos de bovinos.A pregnant heifer with an advanced clinical stage of paratuberculosis was reported in a herd in Argentina. Thus, the animal was euthanized and samples of organs of the cow and its fetus was taken and cultured for bacteriology in specific medium. Tissues were analyzed by histopathology (hematoxylin-eosin and Ziehl-Neelsen staining). Histopathological analysis of the cow’s samples revealed the presence of lesions consistent with paratuberculosis, and Ziehl-Neelsen staining revealed the presence of acid-fast bacilli, whereas the fetal tissues showed absence of lesions but the presence of acid-fast bacilli by Ziehl-Neelsen staining. After growing in specific medium, colonies in tissues from both cow and fetus were positive for IS900-PCR, confirming the presence of Mycobacterium avium subsp. paratuberculosis (MAP). Finally, the isolates were typed by Multiple-Locus Variable-number tandem-repeat Analysis (MLVA), which confirmedthe epidemiological link between them. This study is the first in Argentina to report the detection of MAP that shares an identical MLVA type in a pregnant cow and its fetus. The results of this study are consistent with previous reports and highlight the intra-uterine transmission of MAP as an important source of infection within herds