G. Moschini

PIGE-PIXE analysis of chewing sticks of pharmacological importance

Abstract PIGE and PIXE techniques were employed for the determination of the major, minor and trace elemental concentrations in chewing sticks of pharmacological importance namely: Butyrospermum paradoxum, Garcinia kola, Distemonanthus benthamianus, Bridelia ferruginea, Anogeissus leiocarpus, Terminalia glaucescens and Fagara rubescens, respectively. The concentration of fluorine which is very important for human dental enamel was specially determined using the 19F(p, p′γ)19F reaction. For decades these chewing sticks when used alone without toothpastes have proven to be very efficient, effective and reliable in cleaning the teeth of many people particularly in Nigeria and some other countries in Africa. The teeth of users are usually very strong, clean, fresh and devoid of germs and caries. Even with the advent of modern toothpastes with special additions of fluorine, the use of these popular and efficient chewing sticks is still unabated. Many people including the elite use them solely, a few others combine their use with modern toothpastes and brush. Proton beams produced by the 7 MV CN and 2.5 MV AN 2000 Van de Graaff accelerators at INFN, Laboratori Nazionali di Legnaro (LNL), Padova, Italy were used for the PIGE and PIXE analysis, respectively. Results of this novel study are presented and discussed.

PIXE micro-beam mapping of metals in human peri-implant tissues

Previous investigations did not agree about the possible presence of titanium and other metals in the tissues around endosteal dental implants and joint prostheses. Indeed, while some authors reported diffusion of metals into the tissues, some others did not find evidence of this phenomenon. In the present study, four dental titanium implants, removed with the surrounding tissues from patients at various time intervals after the insertion, were studied by means of the micro-beam proton-induced X-ray emission (PIXE μ-beam) technique, which draws maps showing the tissue distribution of elements with a detection limit of about 1 ppm. One implant was built in commercially pure titanium, two others in titanium coated with titanium plasma spray, and the fourth in Ti–Al–V alloy. Their composition was confirmed by the PIXE μ-beam analyses. The removed samples were embedded in epoxy and processed with a cutting–grinding appliance, mounted on plastic holders, and ground up to a thickness of about 35 μm. Optical microscope examinations were also carried out, to compare the optical findings with the elemental maps obtained with the PIXE μ-beam. One implant, removed after 70 days because the patient had developed peri-implantitis, had some inflammatory soft tissue attached, with no evidence of metal leakage. The other three implants had been removed after 6, 7 and 9 years of valid clinical service, because of the fracture of the prosthetic abutment or the implant stem. At the optical microscope, all these fixtures were embedded in mature bone. The elemental maps indicated small titanium deposits in about 5% of the bone bordering the implants, while aluminum, when present in the fixture, leaked diffusely into the surrounding bone and vanadium was not found in the tissues. These results suggest that titanium may be found occasionally in peri-implantar tissues, but has very little tendency to spread, while the presence of aluminum in the implant alloy may cause an important leakage of this metal.

Quality control of PIXE and PIGE nuclear analytical techniques in geological and environmental applications

Abstract Several powder standard reference materials (SRM) used mainly in geological and environmental applications have been tested for reliability on miligram scale. Specific experimental conditions such as beam energy and diameter, as well as the matrix composition of the analysed samples, determine a lower limit on the necessary mass for which the SRM must be homogeneous. These mass limits have been determined for specific elements and are compared to the minimal mass required for analysis as specified by the certifying body. Since the accuracy of PIGE analysis is often hindered by the presence of interfering nuclear reactions, this narrows down the useful number of elements for which the SRM is certified.

Metal-ion release from titanium and TiN coated implants in rat bone*☆

Abstract Titanium is a good material for dental and orthopaedic implants, but many authors reported that it releases ions into the surrounding tissues and into the serum. Titanium nitride has good mechanical properties and chemical inertless and may be employed as an implant coating material. In this experiment, pure titanium and SiO 2 coated with TiN implants were inserted in the tibia of rats. After thirty days, the bones were taken and examined by a proton microprobe. TiN-coated implants showed a lower ion release into the bone compared with pure titanium. This suggests that TiN may be a good coating for endosseous implants.

X-ray and gamma spectroscopy of coal and coal ash samples

Abstract Large numbers of trace elements occur in coals used in coal burning power plants. In order to assess the environmental impact of the coal fuel cycle, coal and coal ash samples need to be analyzed for a number of toxic and radioactive elements. In this work we demonstrate the analytical use of X-ray and γ-ray spectroscopies. Concentration levels for a number of trace elements were determined by using X-ray fluorescence (XRF), proton-induced X-ray emission (PIXE), proton induced γ-ray emission (PIGE) and γ-radioactivity spectrometry. Special attention was paid to sample preparation procedures and quality control by analysis of standard reference materials.

Multi-element analysis of biopsy samples

Abstract Trace element analysis of biopsy samples represents a difficult analytical problem because of: a) the small amount of material available for analysis and b) the lack of adequate reference materials for microanalytical investigations. In this report we have evaluated the capabilities of X-ray fluorescence in both standard and total reflection geometry, proton-induced X-ray emission and neutron activation analysis for multi-elemental analysis of biopsy samples.

Evaluation of the Extracellular Water in human body by determination of Br concentration in blood plasma

Abstract Extracellular water (ECW) is a component of body composition and an indicator of nutritional status. Oral bromide can be used for determination of ECW. After drug administration, the variation of bromine concentrations in blood plasma were determined by PIXE, and ECW was calculated. The samples were mixed with graphite, in order to overcome charging problem. Low proton current density was used, in order to avoid loss of bromine.

Project of an advanced ISOL facility for exotic beams at LNL

Abstract In the framework of the European program to define a second generation Radioactive Ion Beam facility, LNL are proposing the construction in the next five–seven years of a specialized national facility for RIB originated by fission fragments produced by secondary neutrons. It consists on a two-accelerator ISOL-type facility to provide intense neutron-rich radioactive ion beams of highest quality, in the range of masses between 80 and 160. The conceptual design is based on a high intensity 50xa0MeV (100xa0kW) proton linac as driver and on the availability of the heavy-ion accelerator ALPI as post accelerator. The estimated neutron yield is 2×1014xa0n/s at 0°, high enough to satisfy the demand for an advanced RIB facility. An intense R&D program on different items is actually in progress in collaboration with other Laboratories and University groups and is moving in a European context.

Neutron activation analysis efficiently measures the concentration of trace elements in endoscopic biopsies from the normal and inflamed human colon

Trace element metabolism is altered in inflammatory bowel disease, but the concentrations of trace elements in the intestinal mucosa have not yet been investigated. We evaluated the trace element profile in human colon and the influence of mucosal inflammation. During colonoscopy, biopsies were taken from the colon of 23 ulcerative colitis patients, 15 of whom had active disease and seven control patients. Zinc, iron, and selenium were successfully assayed by neutron activation analysis in as much tissue as was contained in three perendoscopic colonic biopsies. Patients with ulcerative colitis had significantly lower zinc and selenium tissue concentrations and higher iron concentrations than control patients. Zinc and iron concentrations were even altered more in the presence of active disease. Ulcerative colitis is associated with an impaired metabolism of trace elements, even at the mucosal level. J. Trace Elem. Exp. Med. 10:217–224, 1997.

Assessment of selenium status in biological material

Abstract Selenium is an essential trace element to man. Assessment of the selenium status, including its determination in biological materials, has been improved by the advances in analytical methodology. In this report we present the procedures used for selenium determination in different biological material by using nuclear analytical techniques, in particular PIXE, XRF and NAA. The difficulties associated with quality control of these measurements are discussed in some details. Examples of selenium determination in material are presented.