Circular dichroism and thermal melting differentiation of Hoechst 33258 binding to the curved (A(4)T(4)) and straight (T(4)A(4)) DNA sequences

The ability of the B-DNA minor groove ligand Hoechst 33258 to discriminate between prototype curved and straight duplex DNA sequences was investigated by circular dichroism (CD) titrations at the wavelengths of absorbance of the ligand. The sequences were studied either within the framework of the ligated decamers (CA(4)T(4)G)(n) and (CT(4)A(4)G)(n), or within that of the single dodecamers GCA(4)T(4)GC and GCT(4)A(4)GC, to confirm and extend our earlier results based on fluorescence titrations of ligated decamers. A unique, strong binding site is invariantly present in both sequence units. The binding affinity of the drug for the site in the curved A(4)T(4) sequence was found 3- to 4-fold higher compared to the straight sequence. All these features hold true irrespective of the sequence framework, thus confirming that they reflect specific properties of the binding to the two sequences. Ligand binding increases the thermal stability of straight and curved duplex dodecamers to the same extent, thus maintaining the melting temperature differential between the two sequences. However, the different melting patterns and the difference between [total ligand]: [site] ratios needed for site saturation in the two duplexes are in agreement with the difference between binding constants derived from CD measurements, (C) 2002 Elsevier Science B.V. All rights reserved

Hydraulic and mechanical behaviour of cement-bentonite mixtures containing HYPER clay: impact of sulfate attack

Cemented clays are regularly employed as cut-off walls to isolate polluted soils or in ground improvement technologies. The objective of this research was to evaluate the performance of a polymer-treated bentonite (HYPER clay) and its impact on hydraulic and mechanical properties of cement-bentonite (CB) mixtures in contact with sulfates. In this research, bender elements were installed in a hydraulic conductivity cell, to simultaneously monitor the small-strain shear modulus (G(0)) and the hydraulic conductivity (k) of cement-bentonite mixtures. Initially, during permeation with deionized water, an increase of G0 with time was observed, due to cement hydration (hardening). Conversely, after prolonged permeation with sulfates, a decrease of G0 and a gradual increase of k are expected due to degradation of the cemented material. Preliminary results show that k of mixtures containing untreated bentonite increases due to contact with sulfates; conversely, k of mixtures containing HYPER clay remains unaffected. The stiffness modulus G0 was not significantly affected after a sulfate contact period of about 100 days in none of the cement-bentonite mixtures. More extensive monitoring is required for evaluating long-term mechanical degradation. These observations suggest that the use of polymer-treated bentonites could improve the resistance of cement-bentonite mixtures to sulfate attack maintaining a low hydraulic conductivity

Effects of cold conditions on the growth rates of a subtropical conifer

Araucaria angustifolia is an endangered species that occurs in the high and cold regions of southern Brazil. This species has economic importance due to its wood and seeds, as well as playing a fundamental ecological role for the southern fauna and flora. Climate change can affect its distributional area and conservation, making it urgent to investigate the effect of climate on its development. The objective of our study was to investigate how growth rates of A. angustifolia vary in relation to interannual precipitation, temperature, frost and snowfall events. For this purpose, we used two samples obtained from each of 33 individual trees from a forest fragment on the Santa Catarina plateau, Brazil. Classical dendrochronological methods were applied for the preparation and dating of the samples. The tree rings were measured using specialized software. Superposed Epoch analysis was used to test the snow accumulation events. The climatic variables were tested by means of a correlation analysis. The Superposed Epoch analysis was used to test the snow accumulation events. Our results indicate that the species shows significant sensitivity to the climate, with the maximum and minimum absolute temperatures respectively correlated with positive and negative growth rates. Snowfall also reduced growth of A. angustifolia. Overall, extreme cold events are threats to the conservation of the species.Fil: Scipioni, Marcelo Callegari. Universidade Federal de Santa Catarina; BrasilFil: Fontana, Claudia. Universidade de Sao Paulo; BrasilFil: Morales Oliveira, Juliano. Universidad de Vale do Rio dos Sinos; BrasilFil: Santini Junior, Luiz. Universidad Mayor; ChileFil: Roig Junent, Fidel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina. Universidad Mayor; ChileFil: Tomazello Filho, Mario. Universidade de Sao Paulo; Brasi

Trauma- and stressor-related disorders in survivors from a shipwreck: a short report on forensic implications

On January 2012 the Costa Concordia cruise ship sank after hitting an underwater rock off Isola del Giglio, in Tuscany, this resulting in a number of deaths and injuries. After the disaster, several survivors developed psychological disturbances. This led to medico-legal evaluations aimed at assessing the psychiatric sequelae of the accident in order to quantify the permanent biological impairment and the related compensations. In the present manuscript we provide an overview of the results of clinical and medico-legal evaluations performed between 2013 and 2019 on 177 survivors complaining psychological disturbances. The most frequently diagnosed condition was Post-Traumatic Stress Disorder (PTSD; n=90), followed by Acute Stress Disorder (n=37), Adjustment Disorders (n=29) and Generalized Anxiety Disorder (n=5). The results of such evaluations are consistent with evidence indicating the risk of developing PTSD and other trauma- and stressor-related disorders among disaster survivors; further, they highlight the potential relevance in the forensic context of individual elements increasing or decreasing the possibility to develop PTSD among subjects exposed to similar life threatening experiences

Hydraulic and mechanical behaviour of cement-bentonite mixtures containing HYPER clay: impact of sulfate attack

Cemented clays are regularly employed as cut-off walls to isolate polluted soils or in ground improvement technologies. The objective of this research was to evaluate the performance of a polymer-treated bentonite (HYPER clay) and its impact on hydraulic and mechanical properties of cement-bentonite (CB) mixtures in contact with sulfates. In this research, bender elements were installed in a hydraulic conductivity cell, to simultaneously monitor the small- strain shear modulus (G0) and the hydraulic conductivity (k) of cement-bentonite mixtures. Initially, during permeation with deionized water, an increase of G0 with time was observed, due to cement hydration (hardening). Conversely, after prolonged permeation with sulfates, a decrease of G0 and a gradual increase of k are expected due to degradation of the cemented material. Preliminary results show that k of mixtures containing untreated bentonite increases due to contact with sulfates; conversely, k of mixtures containing HYPER clay remains unaffected. The stiffness modulus G0 was not significantly affected after a sulfate contact period of about 100 days in none of the cement-bentonite mixtures. More extensive monitoring is required for evaluating long-term mechanical degradation. These observations suggest that the use of polymer-treated bentonites could improve the resistance of cement-bentonite mixtures to sulfate attack maintaining a low hydraulic conductivity