Validation of a new sampler for radon gas measurements in surface water

Radon gas (Rn-222) in water poses health risks due to radiation exposure, yet it's also an important tracer for studying natural systems. Sampling procedures for Rn-222 analysis are very sensitive to potential losses of the gas to the atmosphere. It requires a well-defined and properly validated protocol to ensure accuracy and reliability. A novel sampler was developed to collect surface water from a distance (e.g. from bridges), addressing logistic challenges posed by topography. The sampler, manually operated, ensures precise depth-specific sampling throughout the water column. A three-stage validation process (technical performance test, uncertainty estimations and preliminary test) was followed to validate the protocol. • The comparison of the technical procedure for analysis and measurement through Liquid Scintillation Counting is statistically robust (one-way ANOVA p-value = 0.96). • For the protocol proposed for Rn-222 determination, the estimated sampling and measurement uncertainties (k = 2) are respectively 5% and 15%. These are compatible with the literature and the laboratory's precision. • Preliminary tests, with meaningful patterns identified and possibly related to the river's hydrodynamics, revealed a very reliable protocol, even in low Rn-222 concentrations.Therefore, the sampler has demonstrated a good analytical reproducibility and was considered validated for Rn-222 determination in surface waters

The SÃo Pedro do Sul Granite (Central Portugal):An HHP Th-rich Rock of the Hesperian Massif

A high heat producing granite pluton has been investigated with the aims of quantifying the budget of heat producing elements and understanding its petrogenesis. The granite produces three times more heat than typical two-mica granites of this region (about 11.2 μWm-3), due mainly to very high Th (average 120 ppm). The pluton has a high abundance of accessory phases and we model about 51 % of the Th to reside in monazite. the remainder probably present largely in thorite. Fission track methods indicate that U is also concentrated in accessory phases, and at least one major phase (probably K-feldspar). Actinide enrichment correlates well with enrichment in the REE and Zr, and we attribute this to the accumulation of accessory mineral phases, although the mechanism is not clear. Combined whole rock major oxide, trace element and oxygen isotope data for the São Pedro do Sul granite (central Portugal) indicate derivation of the parental magma from a metasedimentary source.</p

The SÃo Pedro do Sul Granite (Central Portugal):An HHP Th-rich Rock of the Hesperian Massif

A high heat producing granite pluton has been investigated with the aims of quantifying the budget of heat producing elements and understanding its petrogenesis. The granite produces three times more heat than typical two-mica granites of this region (about 11.2 μWm-3), due mainly to very high Th (average 120 ppm). The pluton has a high abundance of accessory phases and we model about 51 % of the Th to reside in monazite. the remainder probably present largely in thorite. Fission track methods indicate that U is also concentrated in accessory phases, and at least one major phase (probably K-feldspar). Actinide enrichment correlates well with enrichment in the REE and Zr, and we attribute this to the accumulation of accessory mineral phases, although the mechanism is not clear. Combined whole rock major oxide, trace element and oxygen isotope data for the São Pedro do Sul granite (central Portugal) indicate derivation of the parental magma from a metasedimentary source.</p

Antioxidant effect of naturally occurring xanthines on the oxidative damage of DNA bases

The repair of the oxidised radicals of adenine and guanosine by several naturally occurring xanthines was studied. Each pair of DNA purine/xanthine was made to react with the sulphate radical and the decrease of the concentration of both compounds was measured by HPLC as a function of irradiation time. The results show that xanthine efficiently prevents the oxidation of the two DNA purines. Theophyline and paraxanthine repair the oxidised radical of adenine but not the one from guanosine. Theobromine and caffeine do not show any protecting effect. An order of the oxidation potentials of all the purines studied is proposed

Urban Groundwater Processes and Anthropogenic Interactions (Porto Region, NW Portugal)

Groundwater in fissured rocks is one of the most important reserves of available fresh water, and urbanization applies an extremely complex pressure which puts this natural resource at risk. Two-thirds of Portugal is composed of fissured aquifers. In this context, the Porto urban region is the second biggest metropolitan area in mainland Portugal. In this study, a multidisciplinary approach was developed, using hydrogeological GIS-based mapping and modeling, combining hydrogeochemical, isotopic, and hydrodynamical data. In addition, an urban infiltration potential index (IPI-Urban) was outlined with the combination of several thematic layers. Hydrogeochemical signatures are mainly Cl-Na to Cl-SO4-Na, being dependent on the geographic proximity of this region to the ocean, and on anthropogenic and agricultural contamination processes, namely fertilizers, sewage, as well as animal and human wastes. Isotopic signatures characterize a meteoric origin for groundwater, with shallow flow paths and short residence times. Pumping tests revealed a semi- to confined system, with low long-term well capacities (<1 L/s), low transmissivities (<4 m2/day), and low storage coefficients (<10−2). The IPI-Urban index showed a low groundwater infiltration potential, which was enhanced by urban hydraulic and sanitation features. This study assessed the major hydrogeological processes and their dynamics, therefore, contributing to a better knowledge of sustainable urban groundwater systems in fractured mediaThis work was partially financed by FEDER-EU COMPETE Funds and the Portuguese Foundation for the Science and Technology, FCT (UID/GEO/04035/2020, UID/Multi/00611/2020, and GroundUrban project POCI/CTE-GEX/59081/2004), and by the Labcarga|ISEP re-equipment program (IPP-ISEP|PAD’2007/08). The research was also funded by a doctoral scholarship from the Portuguese Foundation for Science and Technology (FCT) to L. Freitas (SFRH/BD/117927/2016). P.M. Carreira acknowledges the FCT support through the FCT-UIDB/04349/2020 project and J.M. Marques recognizes the FCT support through the UID/ECI/04028/2020 project.info:eu-repo/semantics/publishedVersio

Cryptococcus neoformans isolados de pacientes com AIDS

Criptococose é considerada a infecção fúngica sistêmica oportunista mais comum em pacientes com AIDS. Nestes pacientes tem predominado como agente etiológico Cryptococcus neoformans var. neoformans, e muito raramente relata-se C. neoformans var. gattiii, mesmo nas regiões onde se verifica a sua prevalência. Foram estudados 50 pacientes com lesões de criptococose meningoencefálica associada com AIDS. Os isolados foram identificados através de características microscópicas e macroscópicas exibidas em meios de ágar Sabouraud, ágar niger e Christensen. As variedades de C. neoformans foram determinadas pela reação de coloração obtida em meio de L-canavanina glicina-azul de bromotimol (CGB). Em todos os pacientes examinados foram isolados C. neoformans, sendo identificados C. neoformans var. neoformans em 47 isolados e C. neoformans var. gattii em 3. Os resultados encontrados mostram que a criptococose em pacientes com AIDS pode também ser causada por C. neoformans var. gatti, apesar de haver predominância de C. neoformans var neoformans nesta população