A quarter century of wine pigment discovery

The red grape berry pigments, anthocyanins, were characterized in the early 20th century, but investigations of wine pigments were stymied during that era. The question of their identity was a major challenge for wine chemists. A number of techniques showed that the pigments were polymeric in nature. Some structures were postulated by mid-century based on reactions between anthocyanins and condensed tannin, and later postulated wine pigments were observed in model reactions. Some related compounds were then observed in wine. By the end of the 20th century, the ionization of non-volatiles for mass spectrometry opened the door to these compounds. In addition, a new class of compounds was observed, the pyranoanthocyanins, a product of fermentation and aging metabolites with anthocyanins. These compounds possess the pigment stability to SO₂ and pH change that is characteristic of aged red wine. Aging experiments show a dynamic situation with shifts in the population of pigment classes over time. The very large number of diverse pigments explains why it has been so difficult to answer the century-old question of the structure of wine pigments. Our current understanding is founded on the use of mass spectral analysis using electrospray and related ionization techniques over the last 25 years. Future progress will rely on more sophisticated analysis of this very complex mixture of substances. © 2019 Society of Chemical Industry     

Search for high-performance probe-fed stacked patches using optimization

High-performance circular probe-fed stacked patch antenna designs are explored through the use of numerical optimization. New trends are sought to aid understanding and to suggest novel solutions. We describe the optimization technique, present a new design trend relating efficiency and bandwidth to the choice of substrate dielectric, and propose and demonstrate a novel, optimized antenna achieving 33% bandwidth whilst maintaining greater than 80% surface wave efficiency.     

Isolation and characteristics of a protein-polysaccharide complex, secreted by Bifidobacterium adolescentis

Although self-help/mutual-help groups, like Alcoholics Anonymous, are important factors in the recovery of many chemically dependent individuals, the large dropout rates from such groups and the awareness that many who drop out do not return to dependent behavior raises interesting questions about other paths to sustained abstinence and recovery. Current emphasis on treatment outcome studies provides a means for researching factors in both those who recover with and without the assistance of self-help/mutual-help groups. The authors suggest some questions which might be investigated.     

Scan performance of infinite arrays of microstrip patch elementsloaded with varactor diodes

The analysis and scanning characteristics of an infinite array of rectangular microstrip patches each loaded with a varactor diode is presented. The analysis is based on full-wave moment method theory and uses attachment modes to accurately model the current through the feed and the diode. The effect of the biased varactor diode on the scan performance is presented, and it is shown that the impedance mismatch caused by a scan blindness can be eliminated. Other characteristics are also given such as: the active element gain, the efficiency of each loaded microstrip element, and the level of cross polarization generated by the loading of the patch. The effect of the diode biasing level as well as the position of the diode on each radiating element on these scan characteristics is also considered     

Small microstrip patch antenna

A novel small microstrip patch antenna is presented. The probe-fed circular microstrip patch incorporates a single shorting post which significantly reduces the overall size of the antenna. Experimental and theoretical impedance behaviour and radiation characteristics of the modified patch are given. Very good agreement between experiment and theory was achieved     

Factors affecting contrasting results between self-reported and performance-based levels of physical limitation

Molecular electrostatic potential (MEP) maps of certain 3-methoxy flavone derivatives having different anti-picornavirus activities have been studied. Geometries of the molecules were optimised and charge distributions computed using the AM1 molecular orbital method. Hybridization displacement charges (HDC) were combined with the L?wdin charge distributions to compute the MEP maps. Reliability of the method of computing MEP maps was tested by studying certain other molecules for which ab initio MEP results are available. The anti-picornavirus activities of the flavones have been shown to be related with negative MEP values in two regions, one near the 3-methoxy group and another in a diagonally opposite region near the substituent attached to the C7 atom of the molecules.