Francesco Negro

Hepatitis delta virus heterogeneity : a study by immunofluorescence

Hepatitis delta virus (HDV)-RNA shows a microheterogeneity at nucleotide 1015 resulting in the production of two co-terminal forms of the HDV-associated antigen (HDAg), referred to as p24 and p27. In vitro experiments have shown that p24 is localized within the nucleolus, while p27 expression is probably confined to the nucleoplasm. The sequential appearance of these two proteins may play a role in the HDV-induced cell damage. We have examined 12 formalin-fixed human liver biopsies taken at different phases of the natural course of HDV infection. Specimens were assayed for HDAg by direct immunofluorescence with a human IgG reactive towards both p24 and p27. Positive cells were then examined for cytopathological features after hematoxylin/eosin staining. All biopsies contained intranuclear HDAg. However, three different patterns of fluorescence were seen: (1) nucleolar with weak nucleoplasmic; (2) homogeneous nucleoplasmic with negative nucleolus; (3) intense fluorescence diffuse to the whole nucleus. Pattern 1 was found in 15-50% of positive nuclei of all samples, irrespective of the phase of infection, while the remaining positive nuclei mostly showed another pattern (2) of fluorescence. Neither pattern was associated with cytoplasmic eosinophilia. Degenerated hepatocytes, when infected (5%), showed pattern 3 of HDAg fluorescence but were mostly negative for HDV. Therefore, the intranuclear distribution of HDAg, as assayed in vivo, does not seem to correlate with peculiar phases of HDV infection. Different phases of the viral life style, instead, are asynchronously represented within each liver sample.(ABSTRACT TRUNCATED AT 250 WORDS)

Wettability and Color Change of Thermally Treated Poplar OSB after Accelerated Weathering Test

Oriented strand board (OSB) panels are widely marketed for several applications, from 13 building to packaging. The manufacturing of poplar OSB started recently in Northern Italy 14 representing a relevant innovation in the sector since this product is usually made of coniferous 15 wood. The thermal treatment is widely used for reducing the hygroscopicity of wood-based 16 products, nonetheless it influences the mechanical behavior and degrades the main components of 17 wood, which can affect their finishing. Therefore, it is important to know the properties of the 18 treated surfaces. To this purpose, in this study a lot of OSB panels, made of poplar wood, 15 mm 19 thick and with a density of 590 kg/m3, were thermally treated under vacuum conditions at 190 °C 20 for 2 h and then subjected to accelerated weathering. The changes in color and in wettability due to 21 treatment and accelerated weathering were studied. The thermal treatment determined a 22 significant darkening of the color; the accelerated weathering darkened the untreated surfaces and, 23 on the opposite, lightened the thermo-treated surfaces. The wettability decreased after thermal 24 treatment and increased after weathering, more evidently in treated panels. Overall, this study 25 improves the knowledge about the behavior of the surface of thermo-treated poplar OSB, which is 26 relevant for the industrial coating of this product. 27

An innovative composite plywood for the acoustic improvement of small closed spaces

Abstract Poor acoustics is a common problem in many small closed rooms such as offices or dining rooms. Sound absorbing panels used as wall or ceiling coverings can be a remedy. In the present paper, the sound absorption properties of a composite made of two plywood skins bonded to an inner honeycomb core of plywood cells, designed by the authors in a previous study, were improved by drilling the surfaces. The holes communicate with the void cells of the core, activating the Helmholtz resonance effect. The acoustic behavior of small specimens and final-size samples are described, which were also tested in a reverberation chamber and in a real dining room. The developed lightweight composite plywood achieved αmax 0.90 values (maximal sound absorption coefficients) around 400 Hz, i.e. in the low frequency range, resulting in being well suited for various acoustic improvements.