Sizing the length of surface breaking cracks using vibrothermography

Ultrasound excited thermography is used to determine the length of vertical surface breaking cracks. Two methods are proposed based on the analysis of the maximum temperature reached along the line containing the crack and the time at which the maximum temperature occurs. It is shown that, for short bursts, the full width at half maximum of the maximum temperature curve provides the crack length, and that the time at which the maximum temperature occurs increases beyond the crack tip. The range of application of the methods is analysed and the validity is checked taking data on samples containing artificial calibrated cracks.This work has been supported by Ministerio de Economía y Competitividad (DPI2016-77719-R, AEI/FEDER, UE), by Gobierno Vasco (PIBA2018/15) and by Universidad del País Vasco UPV/EHU (GIU16/33)

Lamivudine-resistant HBV strain rtM204V/I in acute hepatitis B

AIMS: To detect HBV rtM204V/I lamivudine-resistant strains in serum of patients with acute hepatitis B and to assess their biological and clinical significance. METHODS: Eighty HBV DNA-positive patients with symptomatic acute hepatitis B observed from 1999 to 2010 were enrolled. A plasma sample obtained at the first observation was tested for HBV mutants in the polymerase region by direct sequencing; the antiviral drug-resistant rtM204V/I mutations, the most frequent HBV mutants in Italy, were also sought by the more sensitive allele-specific polymerase chain reaction (PCR). RESULTS: No HBV mutation associated with resistance to nucleos(t)ide analogues was identified by direct sequencing, whereas allele-specific PCR identified HBV strains carrying the substitution rtM204V/I in 11 (13.7%) patients. Compared with those with the HBV wild strain, patients with rtM204V/I more frequently showed severe acute hepatitis B (36.4% vs 8.7%; p < 0.05) and lower values of serum HBV DNA (1.77 × 10(6) ± 4.76 × 10(6) vs. 1.68 × 10(8) ± 5.46 × 10(8)). In addition, a multivariate analysis identified the presence of a pre-existing HCV chronic infection as independently associated with severe acute hepatitis B (p < 0.05). CONCLUSIONS: HBV rtM204V/I lamivudine-resistant strains were detected in serum of 11 (13.7%) patients with acute hepatitis B by allele-specific polymerase chain reaction. The frequent association of rtM204V/I with a more severe acute hepatitis B and with a lower viral load may suggest that greater and/or more prolonged immune pressure might have induced their selection