A purely instrumental neutron activation analysis method, using high resolution gamma-ray spectrometry with intrinsic Ge and
Ge(Li) detectors, has been used for the analysis of trace elements in copper concentrate samples. Seven rare earth elements
and eight other trace elements were determined with good precision. Standard rocks were also analyzed to check the analytical
procedure, and the results obtained are in good agreement with literature values.
Authors:E. Cortés, N. Gras, L. Muñoz and V. Cassorla
Seven trace elements were determined in milk formulas, powder milk and infant food. Instrumental neutron activation analysis
was used for the analysis of Fe, Zn, Co, Cr and Rb, while As and Cu content was determined using radiochemical neutron activation
analysis. Differences were found in the trace element content of foods of the same type. Milk formulas are comparable with
human milk according to the results obtained for the elements analyzed. The samples of powder cow's milk presented similar
concentrations of the elements studied. Liver with vegetables was found to have the highest Cu content. A meal prepared at
home, made of beef and fresh vegetables showed a higher trace element content than its similar commercial one. An estimation
of the daily intake of the elements analyzed was made and compared with minimum recommended daily ingestion.
Authors:S. Krishnan, E. Cortés, V. Cassorla, L. Muñoz and N. Gras
Mercury pollution in the industrial environment of Chile has been studied using hair as a monitor. Data from samples representing people living in the non-polluted and also from the polluted areas show that, hair is an effective and convenient indicator of environmental mercury pollution in Chile. A major source of mercury pollution and its transport is contaminated water. Hair is found to concentrate mercury from water to an extent of 80 to 500 fold increase in hair concentration. This absorption occurs in a contact time of 24 h and thus provides a means of treating mercury containing water to reduce the mercury to acceptable levels. The capacity of hair for this purpose is about 0.2% which means that, with a kilogram of hair /valued at less than 25 cents/ nearly 20.000 litres of contaminated water /at 0.1 ppm mercury/ can be treated. This is an inexpensive and convenient alternative to conventional ion-exchange processes which are generally very expensive, particularly for developing countries.
Authors:I. Sayago, M. Fernández, J. Fontecha, M. Horrillo, A. Seral-Ascaso, R. Garriga and E. Muñoz
Carbon nanotube (CNT) networks offer fascinating opportunities as active layers for gas sensor devices. We here review our work on the use of CNT fi lms prepared by airbrush spraying as sensitive layers in resistive sensor devices for gas detection. The sensor fi lms were fabricated by airbrushing nanotube dispersions on alumina substrates. Networks of different CNT materials were tested as active sensing element sensors for the detection of pollutant gases (H2, NO2, octane, toluene, NH3). Our results indicate that the CNT structure and chemical functionalization affect both the CNT entanglement within the airbrushed networks and their gas sensing performance. Thus, highly sensitive NO2 and H2 resistive sensors were fabricated out of networks of carboxylic acid functionalized double-walled carbon nanotubes and Pd-functionalized single-walled carbon nanotubes, respectively. Issues related to gas sensing mechanisms of the tested resistive sensors, and device performance dependence upon the sensor operation temperature are also discussed here. All tested resistive sensors provided negligible responses to interfering gases such as NH3, toluene and octane. CNT-based gas sensors made by other fi lm preparation techniques are also reviewed, and their gas sensor performance is compared to those reported here.
Authors:P. Gómez-Ochoa, F. Miana-Mena, M. Muñoz, M. Gascón, J. Castillo, E. Cativiela and F. Gómez
Pluripotent stem cells (PSCs), already described in human beings, are fibroblast-like cells that exhibit a CD34 marker specific for haematopoietic stem cells. In this work we have demonstrated the presence of PSCs in the peripheral blood of pigs, a species frequently used in transplantation studies as an animal model for human diseases. Differentiation into haematopoietic colonies (granulomacrophagic colonies, erythroid colonies and mixed colonies) has been carried out with the peripheral blood of adult and newborn pigs, using solely human commercial media. Peripheral blood mononuclear cells (PBMNCs) were cultured in semisolid methylcellulose based media enriched with recombinant human cytokines, achieving granulomacrophagic-colony forming unit (GM-CFU) and mixed-colony forming unit (Mix-CFU) growth with erythroblastic lineage proliferation in the presence of erythropoietin (Epo). In all the samples CFU growth was associated with the presence of recombinant human cytokine. No evidence of proliferation in control plates without cytokines was found. From liquid medium culture, a population of macrophages and CD34+ fibroblast like cells were retrieved 21 days after sowing. These findings allow us to think about the direct application of this simple and standardised method in several work fields such as the study of pharmacological effects of many drugs over the haematopoietic line and in the study of new strategies in cellular therapy for some human diseases.