Publicaciones No Afiliadas

Objetivo: indagar desde un enfoque histórico en las formas de representación de la memoria reciente desde cuatro sitios vinculados a la represión política durante la dictadura cívico-militar (1973-1990) en la ciudad de Concepción-Chile: la Catedral de Concepción, el Estadio Municipal “Ester Roa Rebolledo”, el Memorial “Homenaje a los estudiantes detenidos desaparecidos” y el “Cuartel Bahamondes”. El nexo entre memoria y territorio se aborda desde el supuesto que éste último configura diferentes formas de memoria extrapolables a otros territorios. Método: Cualitativo documental, que considera investigación de archivos, análisis de fuentes primarias y secundarias escritas e imágenes fotográficas. Resultados: la Catedral y el Memorial se configuran como sitios de memoria por cuanto promueven formas de memoria éticas, políticas y religiosas. En cambio, el Estadio Municipal corresponde a un lugar de memoria invisibilizado, y en el caso del Cuartel, su condición de lugar intencionadamente negado dificulta su reconocimiento como sitio de memoria. Conclusiones: La memoria histórica reciente vinculada a los espacios configura una variada cartografía que abarca dimensiones éticas, estéticas, religiosas y políticas.

Este artículo propone una interpretación polisémica de lo político, atendiendo a un acontecimiento inédito en la historia de Chile, ocurrido durante la dictadura cívico militar (1973 – 1990), a saber, la inmolación de Sebastián Acevedo. Para ello, se realiza un análisis desde la filosofía contemporánea que considera los aportes de Arendt, Foucault, Agamben, entre otros. El principal supuesto es que, en este caso, lo político restaura el ejercicio de la ciudadanía que se configura en la relación coexistente entre los diversos sentidos interpretables desde el acontecimiento. La metodología considera el análisis de fuentes secundarias escritas de tipo académicas y de medios de comunicación de la época. La principal conclusión alude a que los significados vinculados con la palabra, el cuerpo y la violencia promueven la reinscripción de los aspectos políticos en condiciones de excepcionalidad jurídica y violencia de Estado.

Environmental pollution including mutagens from wastewater effluents and discontinuity by man-made barriers are considered typical anthropogenic pressures on microevolutionary processes that are responsible for the loss of biodiversity in aquatic ecosystems. Here, we tested for the effects of wastewater treatment plants (WWTPs), weirs and other stressors on the invertebrate species Gammarus pulex at the population genetic level combining evolutionary ecotoxicology, body burden analysis and testing for exposure to mutagens. Exposure to chemical pollution alone and in combination with the presence of weirs resulted in a depression of allelic richness in native G. pulex populations. Our results suggest that the input of a mutagenic effluent from a WWTP resulted in a strong increase in private alleles over the affected populations. In addition, the presence of weirs along the river disrupted the migration across the river and thus the gene flow between G. pulex upstream and downstream. This study provides strong evidence that the assessment of genetic variation including private alleles together with the contamination of mutagenic and nonmutagenic chemical pollution offers new insights into the regulation of genetic population structure and highlights the relevance of emerging anthropogenic pressures at the genetic level.

We present the whole mitochondrial genome for Galaxias platei, a freshwater fish widely distributed throughout the Patagonian Andes, and compare it with the mitochondrial genome of three congeneric species. The position of G. platei in the phylogenetic reconstruction differs from that shown by earlier studies using multiple markers. We discuss the results in terms of the phylogenetic position of G. platei and the use of whole mitochondrial genomes versus specific regions of multiple organelles.

It is well documented that hydropower plants can affect the dynamics of fish populations through landscape alterations and the creation of new barriers. Less emphasis has been placed on the examination of the genetic consequences for fish populations of the construction of dams. The relatively few studies that focus on genetics often do not consider colonization history and even fewer tend to use this information for conservation purposes. As a case study, we used a 3-pronged approach to study the influence of historical processes, contemporary landscape features, and potential future anthropogenic changes in landscape on the genetic diversity of a fish metapopulation. Our goal was to identify the metapopulation's main attributes, detect priority areas for conservation, and assess the consequences of the construction of hydropower plants for the persistence of the metapopulation. We used microsatellite markers and coalescent approaches to examine historical colonization processes, traditional population genetics, and simulations of future populations under alternate scenarios of population size reduction and gene flow. Historical gene flow appeared to have declined relatively recently and contemporary populations appeared highly susceptible to changes in landscape. Gene flow is critical for population persistence. We found that hydropower plants could lead to a rapid reduction in number of alleles and to population extirpation 50–80 years after their construction. More generally, our 3-pronged approach for the analyses of empirical genetic data can provide policy makers with information on the potential impacts of landscape changes and thus lead to more robust conservation efforts.

Agricultural and urban land use has dramatically increased over the last century and one consequence is the release of anthropogenic chemicals into aquatic ecosystems. One of the rarely studied consequences is the effect of land use change on internal concentrations of organic micropollutants (OMPs) in aquatic invertebrates and its effects on their genotype diversity. Here, we applied population genetic and internal concentrations of OMPs analyses to determine evolutionary implications of chemical pollution on Gammarus pulex populations from a natural and two agricultural streams. Along 14 consecutive months sampled, 26 different OMPs were quantified in G. pulex extracts with the highest number, concentration, and toxic pressure in the anthropogenically stressed stream ecosystems. Our results indicate distinct internal OMP profiles and changes in both genetic variation and genetic structure in streams affected by anthropogenic activity. Genetic variation was attributed to chemical pollution whereas changes in the genetic structure were attributed to environmental disturbances, such as changes in discharge in the impacted stream ecosystems, which worked both independently and in tandem. Finally, we conclude that human-impacted streams are subjected to severe alterations in their population genetic patterns compared to nonimpacted stream ecosystems.

In this paper, we will study the reactivity along with substituent changes in the OH insertion reaction in copper carbenoids. To this end, we have used M06-2X functional with cc-pVDZ for light atoms and LanL2DZ for copper. We have studied the IRC insertion profiles and analysed reactivity indexes such as electrophilicity (ω) and pKa calculations. We have found that with R1 substitutions phenyl group, R2 substitutions amide group lower the reaction barrier considerably. Concerning the substrate reactions, the most favoured substituent is NO2 in para position.

A large set of intramolecular aminoborane-based FLPs was studied employing density functional theory in the H2 activation process to analyze how the acidity and basicity of boron and nitrogen atoms, respectively, affect the reversibility of the process. Three different linkers were employed, keeping the C–C nature in the connection between both Lewis centers: –CH2–CH2–, –CH[double bond, length as m-dash]CH–, and –C6H4–. The results show that significant differences in the Gibbs free energy of the process are found by considering all the combinations of substituents. Of the 75 systems studied, only 9 showed the ability to carry out the process reversibly (ΔGH2 in the range of −3.5 to 2.0 kcal mol−1), where combinations of alkyl/aryl or aryl/alkyl in boron/nitrogen generate systems capable of reaching reversibility. If the alkyl/alkyl or aryl/aryl combination is employed, highly exergonic (non-reversible H2 activation) and endergonic (unfeasible H2 activation) reactions are found, respectively. No appreciable differences in the linker were found, allowing us to continue the analysis with the most entropically favorable linker, the –C6H4– linker. From this, 25 different FLP systems of type 2-[bis(X)boryl]-(Y)aniline (X: H, CF3, C6F5, PFtB, FMes and Y: H, CH3, t-but, Ph, Mes) can be formed. By analyzing the electronic properties of each system, we have found that the condensed-to-boron electrophilicity index ωB+ is inversely related to the ΔGH2. Interestingly, two relationships were found; the first is for alkyl groups (Y: CH3 and t-but) and the second for aryl groups (Y: H, Ph, and Mes), which is intimately related to the proton affinity of each aniline. In addition, it is quite interesting when the frustration degree, given by B⋯N distance dB–N, is brought together with ωB+, since the Image ID:d3sc03992g-t1.gif quotient has unit energy/length corresponding to unit force; concomitantly, a measure of the FLP strength in H–H bond activation can be defined. With this finding, a rational design of this kind of FLP can be performed by analyzing the acidity of boron through condensed-to-boron electrophilicity and knowing the nature of the substituent of nitrogen according to whether the Y is alkyl or aryl, optimizing the H2 reversible activation in a rational way, which is crucial to improve the catalytic performance.

A deeper computational mechanistic study of an environmentally friendly metal-free CO2 reduction process towards obtaining methanol is presented, employing a previously tested kind of intramolecular frustrated Lewis pair (2-[bis(R)boryl]-N,N-dimethylaniline) as the catalyst and H2 as the reducing agent. The Lewis acid strength of the electrophilic boron atom was adjusted to facilitate hydride release by changing the R group, using electron-donating groups (EDGs) based on methylated aryls (Mes and Mes′) and electron-withdrawing groups (EWGs) based on fluorinated alkyls (CF3 and PFtB) and aryls (FMes and C6F5), to analyse its effect on both the H2 splitting and CO2 hydrogenation processes. The acidity of boron was measured from the local electrophilicity index obtained using conceptual density functional theory, where an excellent correlation with the Gibbs free energy of the H2 splitting process was found (R2 = 0.95), indicating that the higher the acid power of boron is, the more exergonic the H2 activation process is. The reversibility of H2 activation directly impacts the CO2 and formic acid hydrogenations, where the less exergonic the H2 splitting process is, the lower the activation energies for these hydrogenation processes are. To obtain methanol at the end, methanediol dehydration forming formaldehyde is crucial, because methanediol has a high energetic barrier, hindering the catalytic cycle from being more efficient. Conversely, formaldehyde can be easily hydrogenated to methanol in the same way as CO2 and formic acid. Finally, the catalytic activity in each case was analysed in terms of the energetic span model, where the local electrophilicity index condensed on boron shows a good linear correlation with the logarithm of the relative turnover frequency (R2 = 0.91), indicating that this reactivity index can be employed to guide the design of optimal catalytic systems to increase its catalytic activity, opening new routes directing future experiments in the field.

The mechanistic paradigm in which the Schmittel cyclization transitions from one-step to stepwise has been investigated through the stabilization of a full hidden intermediate in the framework of the Diabatic Model of Intermediate Stabilization. Hidden intermediate activation was studied in silico employing quasi-classical trajectories and the Electron Localization Function. The stabilization of hidden intermediates achieved by substituting enyne–allenes with cyano and nitro groups generates the appearance of a partially hidden and an explicit intermediate, leading to one-step asynchronous biradical and stepwise biradical/zwitterionic mechanisms, respectively. The mechanistic feature associated with the activation level of the hidden intermediate arises from the Thornton effect and non-RRKM dynamics, where in the case of the CN-substituted system, despite having a single transition state, 54% of the effective trajectories remain in the intermediate zone after 540 fs, indicating that a mixture of mechanisms is observed.