ABSTRACT
The aim of this work was to relate the contribution of mine-derived airborne particulate matter to Ca, Fe, Mn and S content and distribution in Punctelia hypoleucites transplanted to Bajo de la Alumbrera, an important open-pit mine in Catamarca, Argentina. Lichen samples were transplanted to four monitoring sites: two sites inside the mine perimeter and two sites outside the mine. After three months, elemental distribution in samples was analyzed by microparticle-induced X-ray emission (microPIXE), and elemental concentration was determined by specific techniques: Ca and Fe by instrumental neutron activation analysis, Mn by inductively coupled plasma atomic emission spectrometry and S by a turbidimetric method. A differential distribution of S and Ca in thalli transplanted in-mine sites was detected compared to that of samples transplanted outside-mine sites. An overlap of Fe and S in the upper cortex of the apothecium section was observed, leading to infer a mineral association of both elements. Similar association was observed for Ca and S. In addition to these results, the significantly higher concentration detected for S and Mn in in-mine site samples suggests a contribution of Fe, S, Ca and Mn of mining origin to the content and distribution of these elements in P. hypoleucites. MicroPIXE complemented with Mössbauer spectroscopy analysis determined the presence of pyrite particles together with other iron-bearing minerals displaying different degrees of oxidation. These results point to a mining origin of the airborne particulate matter trapped by the lichen thalli transplanted to Bajo de la Alumbrera. These findings indicate that P. Hypoleucites acts as an excellent air quality biomonitor in the Bajo de la Alumbrera mine area.
Subject(s)
Lichens , Parmeliaceae , Particulate Matter/analysis , Lichens/chemistry , Argentina , Minerals/analysis , Environmental Monitoring/methodsABSTRACT
AIM: This work aims at giving an updated report of the worldwide status of Accelerator-Based BNCT (AB-BNCT). BACKGROUND: There is a generalized perception that the availability of accelerators installed in hospitals, as neutron sources, may be crucial for the advancement of BNCT. Accordingly, in recent years a significant effort has started to develop such machines. MATERIALS AND METHODS: A variety of possible charged-particle induced nuclear reactions and the characteristics of the resulting neutron spectra are discussed along with the worldwide activity in suitable accelerator development. RESULTS: Endothermic (7)Li(p,n)(7)Be and (9)Be(p,n)(9)B and exothermic (9)Be(d,n)(10)B are compared. In addition to having much better thermo-mechanical properties than Li, Be as a target leads to stable products. This is a significant advantage for a hospital-based facility. (9)Be(p,n)(9)B needs at least 4-5 MeV bombarding energy to have a sufficient yield, while (9)Be(d,n)(10)B can be utilized at about 1.4 MeV, implying the smallest possible accelerator. This reaction operating with a thin target can produce a sufficiently soft spectrum to be viable for AB-BNCT. The machines considered are electrostatic single ended or tandem accelerators or radiofrequency quadrupoles plus drift tube Linacs. CONCLUSIONS: (7)Li(p,n)(7)Be provides one of the best solutions for the production of epithermal neutron beams for deep-seated tumors. However, a Li-based target poses significant technological challenges. Hence, Be has been considered as an alternative target, both in combination with (p,n) and (d,n) reactions. (9)Be(d,n)(10)B at 1.4 MeV, with a thin target has been shown to be a realistic option for the treatment of deep-seated lesions.
ABSTRACT
La exposición de hembras de sapo Buffo arerarum a aguas del río Reconquista (Provincia de Buenos Aires, Argentina) conduce a la acumulación de zinc (Zn) en sus ovarios. Las hembras tratadas de esta forma son capaces de ovular cuando son inyectadas con macerado de hipófisis, al igual que hembras controles. Los ovocitos obtenidos de hembras tratadas son capaces de fertilizar y desarrollar normalmente hasta el estadío de gástrula, mientras que presentan un 27 por ciento de inhibición del desarrollo embrionario a partir del estadío denominado respuesta muscular. In vivo la microinyección de Zn en ovocitos controles simultáneamente con [U-14C] Glucosa evidenció disminución en la síntesis de glucógeno y en la oxidación de la glucosa a través de la vía de las pentosas. La actividad de la enzima glucosa-6-fosfato deshidrogenasa en ausencia de agregado de Zn fue de 371,8 x 10 -3 U/ml.min. La enzima fue inhibida en vitro por el metal en forma dependiente de la concentración. Utilizando una concentración igual a 1,53mM de Zn, similar a la incorporada en ovario y a la microinyectada en los ensayos con glucosa radiactiva, se alcanzó un 62 por ciento de la máxima inhibición correspondiente a 3mM de Zn (248,7x10-3U/ml.min). Estos resultados concuerdan con un efecto inhibitorio del Zn sobre el desarrollo embrionario, mediado probablemente por una deficiente producción de NADPH, ribosa-5 fosfato y ATP en los ovocitos.
