On the origin of negative target currents during laser ablation of polyethylene

The exposure of a target to a focused laser beam results in the occurrence of a time-varying current between the target itself and the grounded vacuum chamber. This current is composed by three distinct phases, namely the ignition phase, in which the laser pulse drives the electron emission, while electrons coming from the ground through the target holder balance the positive charge generated on the target. The active phase appears at post-pulse times and it is characterized by the presence of peaked structures in the time-resolved current, representing characteristics of the target composition. Lastly, the afterglow phase is determined by a current of electrons flowing from the target to the ground. During the active phase of the target current resulting from polymers ablation with an UV KrF laser, negative target current peaks are observed, whose origin is still unknown. We investigate the dependence of these current structures on the dimensions of the target, using ultra-high molecular weight polyethylene disks of different thickness

The restoration of the Colosso di Barletta: EDXRF analysis

The Colosso di Barletta is an imposing outdoor bronze statue, dating back the V century, located near the Basilica of “Santo Sepolcro” in Barletta (Apulia, Southern Italy). The monument underwent a structural restoration in 1981, during which the Central Institute of Restoration in Rome performed cleaning treatments and consolidation of the patinas. Currently, the Laboratory of Archaeometry of the University of Salento is carrying on a campaign of non-destructive and in situ measurements by using energy dispersion X-ray fluorescence (EDXRF) in order to assess the chemical composition of the alloy and to study its patinas

An estimate of the current risk of transmitting blood-borne infections through blood transfusion in Italy

We conducted a retrospective cohort study to estimate the incidence of major blood-borne agents among Italian blood donors and calculated the risk of infection among blood recipients using the 'incidence/window period model'. The study was conducted among 46 180 blood donors enrolled in six blood centres between 1994 and 1999. During follow-up, seven new infections were confirmed: three donors seroconverted for anti-human immunodeficiency virus (HIV); two for anti-hepatitis C virus (HCV); and two showed hepatitis B surface antigen (HBsAg) reactivity; no cases of syphilis were observed. The incidence rates per 100 000 person/years were: 4.06 (95% CI: 0.82-11.85) for HIV; 2.41 (95% CI: 0.29-8.70) for HCV; and 2.70 (95% CI: 0.32-9.77) for HBsAg; the incidence for total hepatitis B virus (HBV) infection was 9.77 per 100 000 person/years (95% CI: 1.16-35.36). The estimated risk of an infectious blood unit not being detected was: 2.45 (95% CI: 0.13-12.33) per 1 million units for HIV; 4.35 (95% CI: 0.30-22.39) for HCV; and 15.78 (95% CI: 1.16-84.23) for HBV. Overall, an estimated 22.58 per 1 million units are infected. In Italy, the risk of transfusion-transmitted infections is low and is similar to that in other western countries. The introduction of new more sensitive screening tests could reduce the residual risk of transfusion-transmitted infection by 40-80%

Environmental effects on immune system and allergy.

Incidence and severity of allergic diseases of the upper and lower airwys has been increasing throughout this century. The hallmark of these disorders is increased IgE production. Many epoidemiological studies have provided indirect evidence for an increased incidence of asthma and atopy linked to airborne pollution in developed countries. In order to better understand the complex interaction(s) between pollution and allergic diseases, we suggest to consider four fundamentl mechanisms. 1. Increased concentration of airborne allergens in urban areas and workplaces. 2) Adjuvant effect. 3) Xenobiotic interaction(s) with immune system. 4) Effects of pollutants on target organs. In conclusion, although epidemiological and laboratory studies show contrasting results, there is evidence that xenobiotics are involved in the pathogenesis of allergic diseases through specific and non-specific mechanisms

non-metallic armour prior to the first world war

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