Revisiting reef models in the Oligocene of northern Italy (Venetian Southern Alps)

The lower Oligocene coral communities and reefs exposed in the Lessini Shelf of northern Italy may record one of the oldest well-developed barrier reef/lagoon systems of the Cenozoic. However, the rimmed-shelf interpretation has been repeatedly challenged in favour of a ramp model with scattered corals. Based upon a re-analysis of selected localities in the Lessini Shelf, we here provide support for the barrier reef model based on four key observations: 1) systematic changes of coral growth-forms from branching in the proximal areas to massive at the platform margin; 2) a progressive increase of the hydrodynamic energy from the proximal belt towards the more distal environments in the Berici Hills; 3) the occurrence of shallow-water, euphotic conditions throughout the whole depositional system; and 4) the presence of restricted circulation in the proximal environments during sea-level lowstands, with lack of coral colonies. These features, together with the evidence of coral frameworks located on the southeastern edge of the Lessini Shelf, substantiate the occurrence of a reef-rimmed margin. The reefal rim acted as an efficient barrier, with the formation of a landward, wide lagoon protected from the action of waves and currents

Development of 3D-DDTC pixel detectors for the ATLAS upgrade

We report on the development of n-on-p, 3D Double-Side Double Type Column (3D-DDTC) pixel detectors fabricated at FBK-irst (Trento, Italy) and oriented to the ATLAS upgrade. The considered fabrication technology is simpler than that required for full 3D detectors with active edge, but the detector efficiency and radiation hardness critically depend on the columnar electrode overlap and should be carefully evaluated. The first assemblies of these sensors (featuring 2, 3, or 4 columns per pixel) with the ATLAS FEI3 read-out chip have been tested in laboratory. Selected results from the electrical and functional characterization with radioactive sources are here discussed.Comment: 20 pages, 14 figures, presented at 7th International "Hiroshima" Symposium on Development and Applications of Semiconductor Tracking Devices International Conference Center Hiroshima, Japan, Aug. 29-Sep.1, 200

Biodurability and release of metals during the dissolution of chrysotile, crocidolite and fibrous erionite

Background: The mechanisms by which mineral fibers induce adverse effects in vivo are still not well understood. The mechanisms of fiber dissolution in the lungs and subsequent release of metals in the extracellular/intracellular environment must be taken into account. Aim: For the first time, the kinetics of release of metals during the acellular in vitro dissolution of chrysotile, crocidolite and fibrous erionite were determined. Methods: In vitro acellular dissolution of chrysotile, crocidolite, and fibrous erionite-Na was conducted using a solution mimicking the phagolysosome environment active during the phagocytosis process (pH=4.5, at 37 °C). The kinetics of release of a representative selection of metals were determined over a period of three months. Results: Despite the fact that the difference in Fe content between chrysotile and crocidolite is one order of magnitude, the much faster dissolution rate of chrysotile compared to crocidolite prompts greater release of available active surface Fe in the first weeks of the dissolution experiment and comparable amounts after 90 d. Such active iron may promote the formation of toxic hydroxyl radicals. The fast release of metals like Cr, Ni and Mn from chrysotile is also a source of concern whereas the release of V in solution is negligible. Conclusion: Because chrysotile undergoes fast dissolution with respect to crocidolite and fibrous erionite, it behaves like a carrier that releases its metals’ cargo in the lung environment, mimicking the phenomenon that explains the toxicity of nanoparticles. Hence, the toxicity paradigm of a non biodurable fiber like chrysotile should also take into account the release of toxic metals in the intracellular/extracellular medium during the rapid dissolution process

Synchrotron Nano-Diffraction Study of Thermally Treated Asbestos Tremolite from Val d’Ala, Turin (Italy)

Nowadays, due to the adverse health effects associated with exposure to asbestos, its removal and thermal inertization has become one of the most promising ways for reducing waste risk management. Despite all the advances in structure analysis of fibers and characterization, some problems still remain that are very hard to solve. One challenge is the structure analysis of natural micro-and nano-crystalline samples, which do not form crystals large enough for single-crystal X-ray diffraction (SC-XRD), and their analysis is often hampered by reflection overlap and the coexistence of multiple fibres linked together. In this paper, we have used nano-focused synchrotron X-rays to refine the crystal structure of a micrometric tremolite fibres from Val d’Ala, Turin (Italy) after various heat treatment. The structure of the original fibre and after heating to 800◦C show minor differences, while the fibre that was heated at 1000◦C is recrystallized into pyroxene phases and cristobalite

Mineral Fibres and Asbestos Bodies in Human Lung Tissue: A Case Study

One of the open questions regarding the asbestos problem is the fate of the mineral fibres in the body once inhaled and deposited in the deep respiratory system. In this context, the present paper reports the results of an electron microscopy study of both mineral fibres and asbestos bodies found in the lung tissue of a patient who died of malignant mesothelioma due to past occupational exposure. In concert with previous in vivo animal studies, our data provide evidence that amphibole asbestos fibres are durable in the lungs, whereas chrysotile fibres are transformed into a silica-rich product, which can be easily cleared. Amphibole fibres recovered from samples of tissue of the deceased display a high degree of crystallinity but also show a very thin amorphous layer on their surface; 31% of the fibres are coated with asbestos bodies consisting of a mixture of ferroproteins (mainly ferritin). Here, we propose an improved model for the coating process. Formation of a coating on the fibres is a defence mechanism against fibres that are longer than 10 µm and thinner than 0.5 µm, which macrophages cannot engulf. The mature asbestos bodies show signs of degradation, and the iron stored in ferritin may be released and potentially increase oxidative stress in the lung tissue

Emission of fibres and atmospheric pollutants from the thermal treatment of asbestos containing waste (ACW)

Asbestos containing materials (ACMs) are currently landfilled or encapsulated, but this may lead to the release of fibres in the environment. Hence, the destruction of asbestos containing waste (ACW) is now regarded as a preferable option. Thermal treatments based on chrysotile and amphibole asbestos dehydroxylation and recrystallization are being successfully developed for this purpose. This study investigates the emission of asbestos fibres from a prototype for asbestos treatment. Other atmospheric pollutants measured include carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), volatile organic compounds (VOCs), heavy metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) dioxins and furans (PCDD/Fs). Both cement-asbestos and ACM containing polyurethane were tested. No asbestos fibres were found, neither in the emission nor in the solid residue. The concentration of NOx, SO2 and heavy metals are comparable with municipal solid waste incinerators (MSWI) and cement plants. PAHs, BTEX (benzene, toluene, ethylbenzene, xylenes) and styrene are higher in the presence of polyurethane. The presence of polyvinyl chloride (PVC) in the coating of asbestos cement can increase the emission of halogenated VOCs, PCBs and PCDD/Fs. Our results confirm that asbestos inertisation is a safe process for the environment and human health, and economically competitive with landfills

In vitro toxicity of fibrous glaucophane

The health hazard represented by the exposure to asbestos may also concern other minerals with asbestos-like crystal habit. One of these potentially hazardous minerals is fibrous glaucophane. Fibrous glaucophane is a major component of blueschist rocks of California (USA) currently mined for construction purposes. Dust generated by the excavation activities might potentially expose workers and the general public. The aim of this study was to determine whether fibrous glaucophane induces in vitro toxicity effects on lung cells by assessing the biological responses of cultured human pleural mesothelial cells (Met-5A) and THP-1 derived macrophages exposed for 24h and 48h to glaucophane fibres. Crocidolite asbestos was tested for comparison. The experimental configuration of the in vitro tests included a cell culture without fibres (i.e., control), cell cultures treated with 50g/mL (i.e., 15.6g/cm2) of crocidolite fibres and 25-50-100g/mL (i.e., 7.8-15.6-31.2g/cm2) of glaucophane fibres. Results showed that fibrous glaucophane may induce a decrease in cell viability and an increase in extra-cellular lactate dehydrogenase release in the tested cell cultures in a concentration dependent mode. Moreover, it was found that fibrous glaucophane has a potency to cause oxidative stress. The biological reactivity of fibrous glaucophane confirms that this mineral fibre is a toxic agent and, although it apparently induces lower toxic effects compared to crocidolite, exposure to its fibre may be responsible for the development of lung diseases in exposed unprotected workers and population

Indagine sui livelli ematici e tissutali di Se, Zn e Cu in pazienti con patologia neoplastica.

n

Studio caso-controllo dei tassi di Selenio (Se) nel sangue e nei tessuti di soggetti sani o affetti da tumore

n