Screening of antioxidant properties of the apple juice using the front-face synchronous fluorescence and chemometrics

Fluorescence spectroscopy is gaining increasing attention in food analysis due to its higher sensitivity and selectivity as compared to other spectroscopic techniques. Synchronous scanning fluorescence technique is particularly useful in studies of multi-fluorophoric food samples, providing a further improvement of selectivity by reduction in the spectral overlapping and suppressing light-scattering interferences. Presently, we study the feasibility of the prediction of the total phenolics, flavonoids, and antioxidant capacity using front-face synchronous fluorescence spectra of apple juices. Commercial apple juices from different product ranges were studied. Principal component analysis (PCA) applied to the unfolded synchronous fluorescence spectra was used to compare the fluorescence of the entire sample set. The regression analysis was performed using partial least squares (PLS1 and PLS2) methods on the unfolded total synchronous and on the single-offset synchronous fluorescence spectra. The best calibration models for all of the studied parameters were obtained using the PLS1 method for the single-offset synchronous spectra. The models for the prediction of the total flavonoid content had the best performance; the optimal model was obtained for the analysis of the synchronous fluorescence spectra at Delta lambda = 110 nm (R (2) = 0.870, residual predictive deviation (RPD) = 2.7). The optimal calibration models for the prediction of the total phenolic content (Delta lambda = 80 nm, R (2) = 0.766, RPD = 2.0) and the total antioxidant capacity (Delta lambda = 70 nm, R (2) = 0.787, RPD = 2.1) had only an approximate predictive ability. These results demonstrate that synchronous fluorescence could be a useful tool in fast semi-quantitative screening for the antioxidant properties of the apple juices.info:eu-repo/semantics/publishedVersio

Moving in the anthropocene: global reductions in terrestrial mammalian movements

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission

Light Emission from CdS Quantum Dots Stabilized by Sugars

CdS nanoparticles were successfully synthesized using starch, amylopectin and maltodextrin, as a capping agent. Optical properties of the final products have been investigated by photoluminescence spectroscopy and Raman scattering. The atomic force microscopy gave a particle of an average size of approximately 6 nm. Our research reveals that all prepared sugar-quantum dot aqueous solutions were stable against precipitation during the time of their investigation and kept their stability for several months after it

Probing behavior of Aphis fabae and Myzus persicae on three species of grapevines with analysis of grapevine leaf anatomy and allelochemicals

AbstractThe peach-potato aphid Myzus persicae (Sulzer) and the black bean aphid Aphis fabae Scopoli are polyphagous and cosmopolitan hemipterans, therefore they can infest grapevines in all areas of cultivation. Electrical Penetration Graph (EPG) technique was applied to monitor the probing behavior of A. fabae and M. persicae on Vitis amurensis Rupr., Vitis riparia Michaux, and Vitis vinifera L. The content of major flavonoids and stilbenoids in grapevine leaves and epidermal thickness, distance between abaxial leaf surface and phloem, and the simulated shortest pathway from epidermis to phloem that might have affected aphid probing were also analyzed. Aphid probing was limited mainly to non-vascular tissues on the three studied grapevine species. Phloem phase occurred in 32%, 14%, and 6% of A. fabae and in 76%, 39%, and 74% of M. persicae on V. amurensis, V. riparia and V. vinifera, respectively. Phloem phase consisted of only salivation into sieve elements and lasted less than 2.5 minutes on average in all aphids. The time to reach the first phloem phase on grapevines was 5.0 hours in A. fabae and 2.6–3.6 hours in M. persicae. Of the analyzed flavonoids, catechin, epicatechin, and quercetin occurred in all grapevine species, while rutin – in V. amurensis and V. riparia and isorhamnetin only in V. amurensis. Of the analyzed stilbenoids, piceid occurred in all grapevines, resveratrol in V. amurensis and V. vinifera, and ε-viniferin only in V. vinifera. Aphid behavior demonstrated that V. amurensis, V. riparia and V. vinifera are not attractive host plants to A. fabae and M. persicae. It is likely that the content of flavonoids and stilbenoids contributes to the limited susceptibility of the three grapevine species to A. fabae and M. persicae, while the observed slight differences in the anatomical structure of the leaves seem not significant in this context

Brown Bear (Ursus arctos; Eurasia)

The brown bear and cave bear (Ursus spelaeus) diverged in Eurasia approximately 1.2-1.4 million years ago (Loreille et al. 2001) and brown bears subsequently inhabited most of the continent. Here we review how climatic fluctuations during and after the Pleistocene shaped the genetic relationships within Eurasian brown bears, especially focusing on the effects of the Last Glacial Maximum (LGM, 26-19,000 years ago), when most of northern Eurasia was covered with continental ice sheets (Saarma et al. 2007)