F.J. Ager

Cadmium localization and quantification in the plant Arabidopsis thaliana using micro-PIXE

Remediation of metal-contaminated soils and waters poses a challenging problem due to its implications in the environment and the human health. The use of metal-accumulating plants to remove toxic metals, including Cd, from soil and aqueous streams has been proposed as a possible solution to this problem. The process of using plants for environmental restoration is termed phytoremediation. Cd is a particularly favourable target metal for this technology because it is readily transported and accumulated in the shoots of several plant species. This paper investigates the sites of metal localization within Arabidopsis thaliana leaves, when plants are grown in a cadmium-rich environment, by making use of nuclear microscopy techniques. Micro-PIXE, RBS and SEM analyses were performed on the scanning proton microprobe at the CNA in Seville (Spain), showing that cadmium is sequestered within the trichomes on the leaf surface. Additionally, regular PIXE analyses were performed on samples prepared by an acid digestion method in order to assess the metal accumulation of such plants.

Nuclear micro-probe analysis of Arabidopsis thaliana leaves

Phytoremediation is a cost-effective plant-based approach for remediation of soils and waters which takes advantage of the remarkable ability of some plants to concentrate elements and compounds from the environment and to metabolize various molecules in their tissues, such as toxic heavy metals and organic pollutants. Nowadays, phytoremediation technology is becoming of paramount importance when environmental decontamination is concerned, due to the emerging knowledge of its physiological and molecular mechanisms and the new biological and engineering strategies designed to optimize and improve it. In addition, the feasibility of using plants for environmental cleanup has been confirmed by many different trials around the world. Arabidopsis thaliana plants can be used for basic studies to improve the technology on phytoremediation. Making use of nuclear microscopy techniques, in this paper we study leaves of wild type and transgenic A. thaliana plants grown in a cadmium-rich environment under different conditions. Micro-PIXE, RBS and SEM analyses, performed on the scanning proton micro-probe at the CNA in Seville (Spain), prove that cadmium is preferentially sequestered in the central region of epidermal trichome and allow comparing the effects of genetic modifications.

CNA: The first accelerator-based IBA facility in Spain

Abstract The recently created Centro Nacional de Aceleradores (National Center for Accelerators, CNA) in Seville emerges as the first ion beam analysis facility in Spain. The laboratory is based on a 3 MV tandem accelerator model 9SDH-2 of NEC and it is primarily focused on material research and modification by means of IBA techniques: PIXE, RBS, NRA, PIGME and ERDA. The ions are delivered by two ion sources: Alphatross radio-frequency source and SNICS-II sputtering source. The ion beam handling system includes equipment for beam focusing, steering and diagnosis, a 90° analyzing magnet and a seven-port switcher magnet. A system based on magnetic steerers has been installed for high-precision beam energy scanning. In this paper the main elements of the laboratory will be described, focusing on the electronic equipment, detectors and the four beamlines planned for the moment: channeling line, microbeam line, multipurpose vacuum chamber and external microbeam. Moreover, the characteristics of the system as observed until now by means of performance tests, beam energy spread measurements and energy calibration experiments will be summarized.

Influence of preoxidation and annealing treatments on the isothermal oxidation in air at 1173 K of cerium-implanted EN-1.4301 stainless steel

Improvement of the high temperature oxidation behavior of conventional EN-1.4301 (AISI type 304) stainless steel was achieved by implanting cerium ions. Implantation was performed in samples with two different surface treatments: commercial 2B mill finishing and preoxidation in synthetic air. One set of samples was annealed after implantation in order to recover the damage induced in the crystalline structure. Results show that the implantation of Ce greatly improves the oxidation resistance at 1173 K of the EN-1.4301 grade stainless steels and that the annealing treatment after the implantation is beneficial during the subsequent oxidation. Experiments confirm the presence of spinel-type compounds and Cr2O3 and Fe–Cr mixed oxides with high Cr content in the scale, and martensite being the dominating metallic phase. Chromium depletion in the near-surface layers is also described. Results are compared to previously published data on surface modification using La and Ce by pyrolysis of aerosols.

External microbeam set-up at the CNA (Sevilla) and its application to the study of Tartesic jewellery

Abstract A new external microbeam system has been installed recently at the +45° beam line of the 3 MV Pelletron accelerator at the Centro Nacional de Aceleradores (Sevilla, Spain). The facility, based on the system from Oxford Microbeams (OM), includes two sets of slits, a doublet of magnetic quadrupole focusing lenses, a Faraday cup and an accurate positioning device. In addition, a beam profile monitor (BPM) and a quartz viewer have been installed in the line to facilitate the microbeam production. The first PIXE application of the new facility was made in the field of Archaeometry, on the study of Tartesic gold artefacts (700–500 BC, SW of Spain) from Ebora and other archaeological sites. The aim of the analysis was to perform an exhaustive and systematic study about the soldering procedures that were employed by the goldsmiths along the Valley of Guadalquivir River after the Phoenician colonisation.

Thermal and photochemical methods for the preparation of thin films of cermet materials

The synthesis of thin films of Ag-SiO2, Ag-TiO2 and Ag-TiO2-SiO2 cermet materials is described. The preparation method consists in a sol-gel process based in the dip-coating technique to obtain thin films of a composite material containing the oxidized metal and the corresponding ceramic material (TiO2 and/or SiO2). The films, prepared on quartz, were finally heated or irradiated to induce the reduction of the metal and the formation of the cermet materials. An exhaustive characterization of the samples has been carried out by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and Rutherford backscattering. The optical properties of the prepared thin films were determined by UV-VIS absorption spectroscopy and related to the microstructural characteristics of the cermet. Conclusions have been postulated to relate the experimental conditions of the synthesis (thermal or photochemical) to the microstructure and properties of the resulting materials.

Ion beam analysis and alpha spectrometry of sources electrodeposited on several backings

Abstract Alpha sources of several activities were prepared by electrodeposition of natural uranium onto four different backings: stainless steel, Ni, Mo and Ti. The influence of the activity, the type of backing, and the process of heating the source on the energy resolution of the spectra were investigated using alpha spectrometry and Rutherford Backscattering Spectrometry (RBS) techniques. Diffusion profiles of the radioactive deposits in the backings were obtained from RBS and related to the results using alpha spectrometry

Effect of hormone replacement therapy on the elemental contents of uterine tissue

For the past years, different therapies based on steroid hormone supplementation or modulators of estrogen receptors have been used after menopause to prevent or manage osteoporosis. Although these treatments seem to be beneficial, they have some negative effects in the uterus and breast. The objective of this study was to assess variations for the concentrations of K, Ca, Mn, Fe, Cu, Zn, and Se in uterine tissue of Wistar rats. Ovriectomized rats were subjected to estrogen, progesterone, raloxifene, and tibolone supplementation and compared with nonovariectomized control animals. Elemental contents determined by the particle-induced X-ray emission (PIXE) technique revealed major alterations in Fe, Ca, Mn, and Se in the uterus of ovariectomized rats relative to control animals. After ovariectomy, a significant increase in Ca and Fe and a significant decrease in Mn and Se contents were determined in the uterus. For the ovariectomized groups in which animals, received raloxifene, tibolone, estrogen, and estrogen combined with progesterone supplementation, an overall recovery in Mn, Fe, and Se contents was verified. Elemental concentration in the progesterone-supplemented group did not significantly differ from ovariectomized animals receiving placebo. The alterations found for ovariectomized animals receiving placebo and progesterone suggest tissue impairment and trace element imbalance, contrasting with the remaining supplemented groups where an enhancement of tissue activity might justify similar concentration levels relative to controls, because most of the elemental contents altered after ovariectomy.

Elemental composition of sediments determined by TTPIXE

Abstract In this paper, the goodness of the Thick Target Proton Induced X-ray Emission (TTPIXE) technique for the determination of the elemental composition of sediments has been checked through its application to reference sediment samples. The results indicate the suitability of the technique in environmental studies.

Radiological and multi-element analysis of sediments from the Proserpina reservoir (Spain) dating from Roman times

The Proserpina dam was built in Roman times to provide drinking water to Emerita Augusta (todays Mérida in SW Spain). During maintenance work, a sediment core was extracted, offering an excellent opportunity to analyze the historical environmental impacts of the dam and its reservoir over the 2000 years since Roman times. In order to establish an accurate chronology, (14)C ages were determined by accelerator mass spectrometry (AMS). Core samples were assayed for their content in uranium and thorium series isotopes, (40)K, and the anthropogenic radionuclides (137)Cs, (90)Sr, and (239+240)Pu. Potassium-40 presented the highest activity level and was not constant with depth. The uranium and thorium series were generally in equilibrium, suggesting there had been no additional input of natural radionuclides. The presence of (137)Cs was only found in relation with the global fallout in the early 1960s. Multi-element assays were performed using the PIXE and PIGE techniques. Some variations in the multi-element concentrations were observed with depth, but the sediment core could be considered as clean, and no presumptive anthropogenic pollutants were found. Nevertheless, an unusually high Zn content was detected at depths corresponding to pre-Roman times, due to geological anomalies in the area.