Measurement of radium and thorium isotopes in environmental samples by alpha-spectrometry

The final publication is available at Springer via http://dx.doi.org/10.1007/BF02035979[EN] A new method for the determination of low-level radium and thorium isotopes in environmental samples by α-spectrometry is described. Thorium and radium isotopes were chemically separated from the same sample, by using the same tracer (229Th). Two different ways were explored for the concentration process in water samples, obtaining a chemical yield for Ra isotopes between 70–90% in both cases using KMnO4 as carrier and BaCl2 and FeCl3, respectively. The method can also be directly applied for uranium measurements, but in this case there is a limitation on the range of uranium isotopes that can be analyzed.One of us (M.J.R.A.) is grateful to Institución Valenciana de Estudios e Investigación, Spain (IVEI) for fellowshipRodríguez Álvarez, MJ.; Sánchez, F. (1995). Measurement of radium and thorium isotopes in environmental samples by alpha-spectrometry. Journal of Radioanalytical and Nuclear Chemistry. 191(1):3-13. doi:10.1007/BF02035979S3131911W.H.O. Method of Radiochemical Analysis, Univ. of Tokio, Intern. edition, 23 (1967) 117.T. OKUBO, M. SAKANOUE, Geochem. J., 9 (1975) 221.TJOE-PA LIM, N. K. DAVE, N. R. CLOUTIER, Appl. Radiat. Isot., 40 (1989) 63.G. J. HANCOCK, P. MARTIN, Appl. Radiat. Isot., 42 (1991) 63.M. KOIDE, K. W. BRULAND, Anal. Chim. Acta, 75 (1975) 1.K. J. ODELL, Proc. 4th Symp. on the Determination of Radionuclides in Environmental and Biological Materials, April 1983, Ed-Rd Press, London.L. HALLSTADIUS, Nucl. Instrum. Methods Phys. Res., 223 (1984) 266.Radionuclide Transformations, Annals of the ICRP, ICRP Publication 38, Pergamon Press, Vol. 11, 1983, p. 13.M. J. RODRÍGUEZ-ALVAREZ, F. SÁNCHEZ, E. NAVARRO, Proc. 3rd Inter. Summer School, Huelva Spain, M. GARCÍA-LEÓN and G. MADURGA (Eds), World Scientific, Singapore, 1994.M. J. RODRÍGUEZ-ALVAREZ, F. SÁNCHEZ, J. Radioanal. Nucl. Chem., 190 (1995) 123.C. W. SILL, Anal. Chem., 49 (1977) 618.J. L. GASCÓN MURILLO, PhD Thesis, University of Zaragoza, Spain, 1990.M. C. MORÓN, A. MARTINEZ-AGUIRRE, M. GARCÍA-LEÓN, Intern. Conf. on Environmental Radioactivity in the Mediterranean Area, Barcelona, 10–13 May 1988. SNE-ENS, Barcelona, 1988, p. 111.M. YAMAMOTO, K. KOMURA, K. UENO, Radiochim. Acta, 46 (1989) 137.R. GARCÍA-TENORIO, M. GARCÍA-LEÓN, G. MADURGA, C. PIAZZA, Anal. Física B, 82 (1986) 238

Effect of cooling rate during solidification on the hard phases of M23C6-type of cast CoCrMo alloy

Microstructural morphology of CoCrMo alloy by control of the cooling rate during the solidification was investigated. Samples were obtained using both an induction furnace for slow cooling rate and electric arc furnace for fast cooling rate. Microstructural characterizations were performed with metallographic techniques. It was found that the difference between the formation temperature of hard secondary phases of M23C6-type carbides determine the reduction of carbide size by increasing the cooling rate

Resource use efficiency is affected by phytoplankton community changes and geochemical shifts over time in a coastal upwelling area (NE Atlantic).

abstractTime series records are crucial to understand the dynamical processes that occur within phytoplankton communities. This is even more important in the context of the current global change that is already forcing alterations of unprecedented nature and might have unknown consequences for multiple ecosystem processes. Here we present time series analyses of the biogeochemical trends that occurred in the shelf of the Galician coast (station 2 off A Coruña, NE Atlantic) since late 1980s. Upwelling strength and sea temperature in the area have not changed substantially during the last decades. However, while nitrate fertilization from upwelled waters has remained relatively stable, phosphate concentration has increased leading to a negative trend in the N:P ratio. Those trends have impacted the phytoplankton resource use efficiency jointly with the evenness of the community. Phytoplankton used resources more efficiently at higher values of upwelling strength and at lower values of nutrient concentration and evenness. Phytoplankton communities that were more even had higher dinoflagellate diversity contrasting to dominance of diatoms that used resources more efficiently. Moreover, variability in resource use efficiency increased with evenness.IEO (RADIALES-11

Pulsational frequencies of the eclipsing delta-Scuti star HD 172189

The eclipsing delta-Scuti star HD 172189 is a probable member of the open cluster IC 4756 and a promising candidate target for the CoRoT mission. The detection of pulsation modes is the first step in the asteroseismological study of the star. Further, the calculation of the orbital parameters of the binary system allows us to make a dynamical determination of the mass of the star, which works as an important constraint to test and calibrate the asteroseismological models. From a detailed frequency analysis of 210 hours of photometric data of HD 172189 obtained from the STEPHI XIII campaign we have identified six pulsation frequencies with a confidence level of 99% and a seventh with a 65% confidence level in the range between 100-300 uHz. In addiction, three eclipses were observed during the campaign, allowing us to improve the determination of the orbital period of the system.Comment: 6 pages, 7 figure

The Allergenic Structure of the Thaumatinlike Protein Ole e 13 Is Degraded by Processing of Raw Olive Fruits

Background: The thaumatin-like protein (TLP) Ole e 13 in raw olive fruit is responsible for occupational allergy in olive oil mill workers. However,these workers do not experience allergic symptoms after ingestion of edible olive.Objectives: To analyze the presence of IgE-reactive TLP in raw and edible olive fruit and to assess the allergenic potency of both sources.Methods: The content of TLP in raw and edible olive fruit protein extracts was analyzed using immunoblotting with sera from allergic patients and with olive TLP–specific IgG. The structural and immunological stability of TLP were assayed using immunoblotting after treatment of both raw olive and purified TLP with 0.25 M NaOH solution for 24 hours. Olive pollen extract was investigated by immunoblotting for TLP content. Results: The TLP contained in raw olive fruit was not present in edible olives as a result of maceration before human consumption. No TLP was detected in olive pollen using specific IgG or sera from patients allergic to olive fruit. Sera from patients allergic to olive pollen did not react with purified TLP. Conclusions: IgE-reactive TLP is not present in edible olive, thus explaining the low number of patients allergic to this highly consumed fruit. Patients allergic to olive pollen are not sensitized to TLP and, therefore, not expected to be at risk of food allergy to olive fruit or TLP plant source

The field high-amplitude SX Phe variable BL Cam: results from a multisite photometric campaign. II. Evidence of a binary - possibly triple - system

Short-period high-amplitude pulsating stars of Population I ($\delta$ Sct stars) and II (SX Phe variables) exist in the lower part of the classical (Cepheid) instability strip. Most of them have very simple pulsational behaviours, only one or two radial modes being excited. Nevertheless, BL Cam is a unique object among them, being an extreme metal-deficient field high-amplitude SX Phe variable with a large number of frequencies. Based on a frequency analysis, a pulsational interpretation was previously given. aims heading (mandatory) We attempt to interpret the long-term behaviour of the residuals that were not taken into account in the previous Observed-Calculated (O-C) short-term analyses. methods heading (mandatory) An investigation of the O-C times has been carried out, using a data set based on the previous published times of light maxima, largely enriched by those obtained during an intensive multisite photometric campaign of BL Cam lasting several months. results heading (mandatory) In addition to a positive (161 $\pm$ 3) x 10$^{-9}$ yr$^{-1}$ secular relative increase in the main pulsation period of BL Cam, we detected in the O-C data short- (144.2 d) and long-term ($\sim$ 3400 d) variations, both incompatible with a scenario of stellar evolution. conclusions heading (mandatory) Interpreted as a light travel-time effect, the short-term O-C variation is indicative of a massive stellar component (0.46 to 1 M_{\sun}) with a short period orbit (144.2 d), within a distance of 0.7 AU from the primary. More observations are needed to confirm the long-term O-C variations: if they were also to be caused by a light travel-time effect, they could be interpreted in terms of a third component, in this case probably a brown dwarf star ($\geq$ 0.03 \ M_{\sun}), orbiting in $\sim$ 3400 d at a distance of 4.5 AU from the primary.Comment: 7 pages, 5 figures, accepted for publication in A&

Absence of Face-specific Cortical Activity in the Complete Absence of Awareness: Converging Evidence from Functional Magnetic Resonance Imaging and Event-related Potentials

In this study, we explored the neural correlates of perceptual awareness during a masked face detection task. To assess awareness more precisely than in previous studies, participants employed a 4-point scale to rate subjective visibility. An event-related fMRI and a high-density ERP study were carried out. Imaging data showed that conscious face detection was linked to activation of fusiform and occipital face areas. Frontal and parietal regions, including the pre-SMA, inferior frontal sulcus, anterior insula/frontal operculum, and intraparietal sulcus, also responded strongly when faces were consciously perceived. In contrast, no brain area showed face-selective activity when participants reported no impression of a face. ERP results showed that conscious face detection was associated with enhanced N170 and also with the presence of a second negativity around 300 msec and a slow positivity around 415 msec. Again, face-related activity was absent when faces were not consciously perceived. We suggest that, under conditions of backward masking, ventral stream and fronto-parietal regions show similar, strong links of face-related activity to conscious perception and stress the importance of a detailed assessment of awareness to examine activity related to unseen stimulus events