Current and future experimental approaches in the study of grape and wine polyphenols interacting gut microbiota

Interactions between polyphenols and gut microbiota are indeed a major issue of current interest in food science research. Knowledge in this subject is progressing as the experimental procedures and analysis techniques do. The aim of this article is to critically review the more leading-edge approaches that have been applied so far in the study of the interactions between grape/wine polyphenols and gut microbiota. This is the case of in vitro dynamic gastrointestinal simulation models that try to mitigate the limitations of simple static models (batch culture fermentations). More complex approaches include the experimentation with animals (mice, rats, pigs, lambs and chicks) and nutritional intervention studies in humans. Main advantages and limitations as well as the most relevant findings achieved by each approach in the study of how grape/wine polyphenols can modulate the composition and/or functionality of gut microbiota, are detailed. Also, common findings obtained by the three approaches (in vitro, animal models and human nutritional interventions) such as the fact that the Firmicutes/Bacteroidetes ratio tends to decrease after the feed/intake/consumption of grape/wine polyphenols are highlighted. Additionally, a nematode (Caenorhabditis elegans) model, previously used for investigating the mechanisms of processes such as aging, neurodegeneration, oxidative stress and inflammation, is presented as an emerging approach for the study of polyphenols interacting gut microbiota. © 2020 Society of Chemical Industry     

Effect of X-rays on poly(vinylidene fluoride) in X-ray photoelectron spectroscopy

The polymer poly(vinylidene fluoride) (PVDF) was irradiated with X-rays produced by a nonmonochromatic (MgKα) source and the structural and electronic PVDF surface modifications were studied by X-ray photoelectron spectroscopy (XPS). Changes in the shape and intensity of the C_1s and F_1s lines show that a PVDF degradation consisting of the polymer defluorination takes place. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2125–2129, 1998     

Isolation of a powerful antioxidant from Olea europaea fruit-mill waste: 3,4-Dihydroxyphenylglycol

Nutritional and antioxidant properties of phenolic compounds are important in relation to human health and palatability of products. 3,4-Dihydroxyphenylglycol (DHPG) is a strong antioxidant found in small amounts in virgin olive oil and table olives, with an antioxidant activity even higher than that of the powerful hydroxytyrosol. The origin of this antioxidant is completely unclear since has never been reported as a free plant metabolite. In this respect possible precursors of DHPG have also been discussed in this study. The presence of soluble compounds that either contain DHPG in their molecular structure or act as substrates for its synthesis has been showed for the first time. The quantities of DHPG recovered in olive drupe tissue by thermal treatment exceed widely the values indicated in the literature, showing the release or formation of additional DHPG from precursors after heating. In addition, DHPG obtained under certain extraction conditions from fresh solid waste of two-phase olive oil extraction systems (alperujo) is its most important phenolic compound. Therefore, the solid olive waste is a good source of this simple monomer phenol. The chemical structure, purity and racemic nature of isolated DHPG were also analysed for the first time by NMR experiments.     

Vertical versus scanning lidar measurements in a horizontally homogeneous atmosphere

This study compares the aerosol backscatter and extinction coefficients retrieved from vertical elastic and Raman channels with those derived from measurements with multiangle elastic channels. Retrievals from simulated vertical signals at 355 nm, 387 nm, 532 nm, and 607 nm are compared with those from multiangle measurements (at 15 elevation angles) at 355 nm and 532 nm. The atmosphere is considered horizontally homogeneously stratified. For the backscatter coefficient, the Raman backscatter solution and the multiangle solution are considered. For the extinction coefficient, retrievals from the Raman channel and multiangle measurements are compared. The comparison shows that in the presence of horizontal homogeneity, multiangle measurements provide more reliable results, especially for the aerosol extinction coefficient. The uncertainty in the measured signals is considered in an alternative approach to quantify the relative error of the retrieved profiles with respect to the models (linear regression between retrieval and model).     

Notes on Rayleigh scattering in lidar signals

Classical and quantum formulations are used to estimate Rayleigh scattering within lidar signals. Within the classical approach, three scenarios are used to characterize atmospheric molecular composition: 2-component atmosphere (N2 and O2), 4-component atmosphere (N2, O2, Ar, and CO2), and 5-component atmosphere (N2, O2, Ar, CO2, and water vapor). First, analysis focuses on Rayleigh scattering, showing the relative difference between the three scenarios within classical approach. The relative difference in molecular scattering between 2(4)-component atmosphere and 5-component atmosphere is below ~1%. The second analysis focuses on the lidar retrieval of aerosol backscatter and extinction coefficients showing the effect of different molecular formulations. A relative difference of ±3% was found between the molecular formulation of 2-component atmosphere and the molecular formulation of 5-component atmosphere. Consideration of the Raman rotational lines blocked by the interference filter is important for the elastic channels, but of little significance in the N2 Raman channel. For lidar retrieval of aerosol profiles, the 5-component approximation is the best when the water vapor profile is known, but 2-component is still adequate and quite accurate when water vapor is only poorly known.     

Simultaneous optical signal-to-noise ratio and differential group delay monitoring based on degree of polarization measurements in optical communications systems

We present a simultaneous optical signal-to-noise ratio (OSNR) and differential group delay (DGD) monitoring method based on degree of polarization (DOP) measurements in optical communications systems. For the first time in the literature (to our best knowledge), the proposed scheme is demonstrated to be able to independently and simultaneously extract OSNR and DGD values from the DOP measurements. This is possible because the OSNR is related to maximum DOP, while DGD is related to the ratio between the maximum and minimum values of DOP. We experimentally measured OSNR and DGD in the ranges from 10 to 30 dB and 0 to 90 ps for a 10 Gb/s non-return-to-zero signal. A theoretical analysis of DOP accuracy needed to measure low values of DGD and high OSNRs is carried out, showing that current polarimeter technology is capable of yielding an OSNR measurement within 1 dB accuracy, for OSNR values up to 34 dB, while DGD error is limited to 1.5% for DGD values above 10 ps. For the first time to our knowledge, the technique was demonstrated to accurately measure first-order polarization mode dispersion (PMD) in the presence of a high value of second-order PMD (as high as 2071 ps(2)).     

Application of corporate social responsibility approach in Bulgaria to support sustainable tourism development

The rapidly developing tourism industry in Bulgaria in the last 15?years, especially at the Black sea coast, contributed to an entire change in the accommodation sector. The growth was due to unseen construction of new accommodation facilities and entire renovation of the existing ones. At the same time the tourism industry suffers from many social problems: lack of staff, shortage of qualified staff especially in the high-star hotels, very high rate of turnover, flow of Bulgarian staff abroad. The bigger mobility of the employees is facilitated by the seasonal character of the industry, knowledge of foreign languages, difference in payments, as well as in the nature of work. Overall, this leads to lost training investments, reduces the incentives for employers to provide training, causes lower quality services in hotels, and finally impacts negatively the competitiveness of the hotel sector in Bulgaria and its sustainable development. The paper presents the practical experience and conclusions from a corporate social responsibility (CSR) assessment in 25 Bulgarian hotels regarding the social issues of the CSR: human resource management, occupational safety and health, human and labour rights, stakeholder and community involvement, customer satisfaction. The most important social problems identified are: deficiency in management skills, deficiency in organised (external) stakeholder dialogue, lack of qualified staff in certain professions, lack of investment in training, high turnover, low motivation, conflicts related to wage levels, overtime, etc. A set of key performance indicators related to social responsibility is suggested and analysed. The benchmarking process is discussed and exemplary benchmarks are quoted. The most frequently proposed measures by the hotel CSR teams to improve the social responsibility in the hotels are reviewed.