The role of extracellular DNA in uranium precipitation and biomineralisation.

Bacterial extra polymeric substances (EPS) have been associated with the extracellular precipitation of uranium. Here we report findings on the biomineralisation of uranium, with extracellular DNA (eDNA) used as a model biomolecule representative of EPS. The complexation and precipitation of eDNA with uranium were investigated as a function of pH, ionic strength and varying concentrations of reactants. The role of phosphate moieties in the biomineralisation mechanism was studied by enzymatically releasing phosphate (ePO4) from eDNA compared to abiotic phosphate (aPO4). The eDNA-uranium precipitates and uranium minerals obtained were characterised by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FT-IR) spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-Ray analysis (SEM-EDX), X-Ray Powder Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). ATR-FT-IR showed that at pH 5, the eDNA-uranium precipitation mechanism was predominantly mediated by interactions with phosphate moieties from eDNA. At pH 2, the uranium interactions with eDNA occur mainly through phosphate. The solubility equilibrium was dependent on pH with the formation of precipitate reduced as the pH increased. The XRD data confirmed the formation of a uranium phosphate precipitate when synthesised using ePO4. XPS and SEM-EDX studies showed the incorporation of carbon and nitrogen groups from the enzymatic orthophosphate hydrolysis on the obtained precipitated. These results suggested that the removal of uranium from solution occurs via two mechanisms: complexation by eDNA molecules and precipitation of a uranium phosphate mineral of the type (UO2HPO4)·xH2O by enzymatic orthophosphate hydrolysis. This demonstrated that eDNA from bacterial EPS is a key contributor to uranium biomineralisation

Reconsidering prenatal screening: an empirical-ethical approach to understand moral dilemmas as a question of personal preferences

In contrast to most Western countries, routine offer of prenatal screening is considered problematic in the Netherlands. The main argument against offering it to every pregnant woman is that women would be brought into a moral dilemma when deciding whether to use screening or not. This paper explores whether the active offer of a prenatal screening test indeed confronts women with a moral dilemma. A qualitative study was developed, based on a randomised controlled trial that aimed to assess the decision-making process of women when confronted with a test offer. A sample of 59 women was interviewed about the different factors balanced in decision-making. Participants felt themselves caught between a need for knowledge and their unwillingness to take on responsibility. Conflict was reported between wishes, preferences and ethical views regarding parenthood; however, women did not seem to be caught in a choice between two or more ethical principles. Participants balanced the interests of the family against that of the fetus in line with their values and their personal circumstances. Therefore, we conclude that they are not so much faced with an ethical dilemma as conflicting interests. We propose that caregivers should provide the opportunity for the woman to discuss her wishes and doubts to facilitate her decision. This approach would help women to assess the meaning of testing within their parental duties towards their unborn child and their current offsprin

“También / tampoco: marcadores de modalidad deóntica”

This article is an investigation into the modal significance of the discourse markers también/tampoco in Spanish conversational discourse. The analysis highlights their function as deontic modal particles. We also illustrate how these particles can assume diverse values related to verbal politeness. The comparison between Spanish and Italian reveals interesting similarities and differences between tampoco and the presuppositional particle mica

Limits on excited tau leptons masses from leptonic tau decays

We study the effects induced by excited leptons on the leptonic tau decay at one loop level. Using a general effective lagrangian approach to describe the couplings of the excited leptons, we compute their contributions to the leptonic decays and use the current experimental values of the branching ratios to put limits on the mass of excited states and the substructure scale.Comment: 10 pages, 6 figures, to be published in Phys. Rev.

Dipolar origin of the gas-liquid coexistence of the hard-core 1:1 electrolyte model

We present a systematic study of the effect of the ion pairing on the gas-liquid phase transition of hard-core 1:1 electrolyte models. We study a class of dipolar dimer models that depend on a parameter R_c, the maximum separation between the ions that compose the dimer. This parameter can vary from sigma_{+/-} that corresponds to the tightly tethered dipolar dimer model, to R_c --> infinity, that corresponds to the Stillinger-Lovett description of the free ion system. The coexistence curve and critical point parameters are obtained as a function of R_c by grand canonical Monte Carlo techniques. Our results show that this dependence is smooth but non-monotonic and converges asymptotically towards the free ion case for relatively small values of R_c. This fact allows us to describe the gas-liquid transition in the free ion model as a transition between two dimerized fluid phases. The role of the unpaired ions can be considered as a perturbation of this picture.Comment: 16 pages, 13 figures, submitted to Physical Review

Rapid diagnosis of human brucellosis by SYBR Green I-based real-time PCR assay and melting curve analysis in serum samples

SUMMARYThe aim of this study was to develop a LightCycler-based real-time PCR (LC-PCR) assay and to evaluate its diagnostic use for the detection of Brucella DNA in serum samples. Following amplification of a 223-bp gene sequence encoding an immunogenetic membrane protein (BCSP31) specific for the Brucella genus, melting curve and DNA sequencing analysis was performed to verify the specificity of the PCR products. The intra- and inter-assay variation coefficients were 1.3% and 6.4%, respectively, and the detection limit was 5 fg of Brucella DNA (one genome equivalent). After optimisation of the PCR assay conditions, a standard curve was obtained with a linear range (correlation coefficient = 0.99) over seven orders of magnitude from 107 to 10 fg of Brucella DNA. The LC-PCR assay was found to be 91.9% sensitive and 95.4% specific when tested with 65 negative control samples and 62 serum samples from 60 consecutive patients with active brucellosis. The assay is reproducible, easily standardised, minimises the risk of infection in laboratory workers, and has a total processing time of < 2 h. It could therefore form a promising and practical approach for the rapid diagnosis of human brucellosis

Una aproximación hacia la equidad en las penas en materia de niños, niñas y adolescentes imputados por la ley penal en Mendoza

Desde la presente investigación se trató de corroborar la medida en la que los factores de riesgo asociados a la deprivación socio-cultural en los menores, inciden en la comisión de delitos graves. Con este propósito, en la primer etapa del trabajo, se analizó la totalidad de casos en los que menores de entre 16 y 18 años de edad, cometieron homicidios en la provincia de Mendoza, entre los años 2003 y 2007. En una segunda etapa de trabajo, se analizó también, una muestra de casos con características similares, pero esta vez, de jóvenes que cometieron el delito de abuso sexual.