RESUMO
Spatial-frequency domain imaging (SFDI) has been developed as an emerging modality for detecting early-stage bruises of fruits, such as apples, due to its unique advantage of a depth-resolved imaging feature. This paper presents theoretical and experimental analyses to determine the light penetration depth in apple tissues under spatially modulated illumination. Simulation and practical experiments were then carried out to explore the maximum light penetration depths in 'Golden Delicious' apples. Then, apple experiments for early-stage bruise detection using the estimated reduced scattering coefficient mapping were conducted to validate the results of light penetration depths. The results showed that the simulations produced comparable or a little larger light penetration depth in apple tissues (~2.2 mm) than the practical experiment (~1.8 mm or ~2.3 mm). Apple peel further decreased the light penetration depth due to the high absorption properties of pigment contents. Apple bruises located beneath the surface peel with the depth of about 0-1.2 mm could be effectively detected by the SFDI technique. This study, to our knowledge, made the first effort to investigate the light penetration depth in apple tissues by SFDI, which would provide useful information for enhanced detection of early-stage apple bruising by selecting the appropriate spatial frequency.
RESUMO
This work presents the results from a series of bistatic sea surface scattering experiments conducted in shallow water using a parametric acoustic array as a source and a receiver comprising a horizontal linear array. The experiments measured scattering at three frequencies (4, 8, and 15 kHz) and at three incident grazing angles (13º, 20º, and 30º). The measurements were made over a 5 day period during which a variety of environmental conditions were encountered. This paper provides an outline of the experiments and presents some results for the forward scattering strength. The results show that the wave direction has a significant effect on the surface forward scattering. At each incident grazing angle, the fluctuations of scattering strength due to environmental conditions decreases as the frequency increases.
RESUMO
Resistant HCV variants carrying NS5B S282T mutation confer reduced sensitivity to sofosbuvir, the sole marketed NS5B polymerase inhibitor. On the basis of the finding that 2'-α-F-2'-ß-C-methylcytidine 5'-triphosphate (8) was more potent than sofosbuvir's active metabolite on inhibition of both wild-type and S282T mutant polymerase, a dual-prodrug approach has been established. Twenty-nine phosphoramidates with N4-modified cytosine were designed, synthesized, and evaluated for anti-HCV activity. The results showed that compounds 4c-4e and 4m (EC50 = 0.19-0.25 µM) exhibited comparable potency to that of sofosbuvir (EC50 = 0.15 µM) on inhibition of wild-type replicons. Notably, 4c (EC50 = 0.366 µM) was 1.5-fold more potent than sofosbuvir (EC50 = 0.589 µM) on inhibition of S282T mutant replicons. In vitro metabolic studies disclosed the possible metabolic pathways of 4c. The toxicity study results indicated a good safety profile of 4c. Together, 4c-4e and 4m hold promise for drug development for the treatment of HCV infection, especially the resistant variants with NS5B S282T mutation.
