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Silver artefacts and particularly ancient silver artefacts present the serious problem of the black look due to ambient contamination. The black colour is the consequence of the layer forming on the surface made of acanthite and jalpaite, both compounds are sulphur composts. Recently UV laser cleaning technique has demonstrated to be very promising in processing of cultural artefacts. To operate on artefacts without to contaminate the bulk, first we determined the laser fluence threshold of the bulk, second we controlled the surface compounds and at the end we operated the laser irradiation. In this work we utilised certified silver and silver/copper samples in order to perform preliminary studies. The threshold fluence we found were 780 and 510 mJ/cm2 for the Ag pure and for the Ag/Cu alloy, respectively. The jalpaite concentration on Ag/Cu sample increased after the laser dose of 25 J/cm2, while for higher laser dose its value lowered pointing out that complex processes take part during the laser application. As a successful of our studies we applied the technique on a Carlino coin made of silver coined in 1689 under King Carlo II. The analyses were performed by two different techniques able to find the percentage of elements and the chemical compounds; the EDXRF and the XRD. We found that the sulphur concentration decreased on laser dose. Operating on the coin up to a dose of 280 J/cm2 the sulphur concentration deceases up to 20 %, while the coin look becomes clear just after a 50 J/cm2.

Results about the efficiency of the laser cleaning on the reduction of corrosion products from the surface of ancient coins are reported. In this work an ancient copper coin datable from 1500 to 1600 A.D. and a UV excimer laser were utilized. The goal of this work consists to study the potentiality of UV laser treatment in the reduction of the chlorine concentration on the coin surface which is the main responsible of the corrosion processes of the ancient coins. We used Energy Dispersive X-Ray Fluorescence (EDXRF) and X-Ray Diffraction (XRD) techniques to estimate the chemical composition of the coin surface, before and after UV excimer laser cleaning. In particular, we measured the chlorine, copper and calcium concentrations. We found that a radiation dose of about 19 J/cm 2 was able to reduce the chlorine concentration from 2.3 % w/w to 0.6 % w/w without damaging the metal bulk. Keywords: ancient coins; patina ; copper chlorides; laser cleaning; EDXRF portable apparatus

PTS, PM10 and PM2.5 samples have been collected at a rural site of south-east Italy (40 degrees 20' 13" N; 18 degrees 6' 47" E) from June to October, 2004 to investigate natural and anthropogenic contributions on particulate matter and heavy metal mass concentrations. It is shown that sharp-peak particulate-matter concentrations have been recorded during most African dust outbreaks occurred over south-east Italy. In particular, PM10 concentrations exceeding the 24-hour limit value of 50 microg/m3 have been monitored during dust events. Al, Cd, Cr, Cu, Fe, Mn, V, Ni, Pb, and Zn metal concentrations have been evaluated by an inductively coupled plasma atomic emission spectrometer and Al mass concentrations >500 ng/m3 have been observed in PTS and PM10 samples during the advection of African dust particles. Accordingly to geochemical calculations Al, Fe, and Mn, have a significant crustal origin while, Cd, Cu, Pb, and Zn are of anthropogenic origin. Moreover, Fe resulted predominant in the coarse particle fraction, while Ni, Pb, V, and Zn were predominant in the fine particle fraction. It is also shown that Cd, Mn, Ni, Pb, and V concentrations never exceeded guide and/or limit values recommended by the World Health Organization and the European Council Directives.

We present some preliminary results relevant to the ability of the purple non-sulphur bacterium Rhodobacter sphaeroides strain R26.1 to sequester heavy metals from contaminated growth media. The microorganism was chosen because of its significant tolerance to relatively high concentrations of the investigated ions Ni2+, Co2+, CrO4(2-), and MoO4(2-). In this paper the optimized conditions for the bacterial growth and the sample preparation used to infer the ability of the microorganism to cope with metal pollutants are presented. Elemental analysis has been performed by inductively coupled plasma atomic emission spectrometry previous mineralization of samples by a microwave system.

In this work we report the preliminary experimental results on the selective ablation of sulphur in ancient stones. The sulphur concentration was reduced after laser action. For this goal an excimer laser operating at 308 nm wavelength and time duration of 20 ns was used. In order to estimate the sulphur concentration before and after laser cleaning, a portable apparatus for energy-dispersive X-ray fluorescence (EDXRF) was utilised. The processed sample were characterized by an initial sulphur concentration of 2.8% w/w. After the laser treatment, sulphur concentration decreased after a total deposited energy of about 30 J/cm 2 up to 1.2% w/w value. Due to the porosity of the stone, in fact, it is difficult to eliminate completely the S presence in the composition of the stones. It was also observed that after a few laser shots the initial black area of the stone became white showing in this way the great potential of the laser action on the cleaning process of the pietra leccese.

We report here the results about the sulphur concentration in ancient stones and its removal after the application of UV laser action. A portable apparatus for energy-dispersive X-ray fluorescence (EDXRF) was utilised to measure the sulphur concentration before and after laser cleansing. After laser application the sulphur concentration decrased to 1.2% w/w whilst the initial value was 2.8% w/w. The laser energy density was about 1 J/cm2 and the efficient shot number was approximately 30 with a rate of 1Hz.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

As is well known from literature, the grinding process, which is an unavoidable step in sample preparation, may strongly modify the physical properties of chrysotile through amorphisation. The aim of this work is to establish the proper milling time to apply to the samples before an accurate X-ray powder diffraction quantitative analysis. We have used the RIR (reference intensity ratio) analytical method, based on the measurement of the ratio I/Is between the intensity of the strongest line of an analyte and the intensity of the analytical peak of a standard material, when they are thoroughly mixed 50:50 by weight. We have studied how the RIR value changes as a function of the milling time of the sample and how the accuracy of this quantitative method is affected.