Effects of Genetic, Pre- and Post-Harvest Factors on Phenolic Content and Antioxidant Capacity of White Asparagus Spears

The effects of genetic, pre-harvest (season of harvest, spear diameter, spear portion and spear tip color) and post-harvest factors (storage and domestic preparation practices, e.g., peeling and cooking) on total phenolic, flavonoid and ascorbic acid content of white asparagus spears and their correlation with antioxidant capacity (DPPH and FRAP) were studied. Results showed that genetic material was important for the total phenolic content but not season of harvest, spear diameter or storage. Violet spear tips and apical spear portions showed the largest amount of total phenolics. Peeling did not affect total phenolics in fresh asparagus, whereas it reduced their content in stored asparagus, while cooking resulted in an increase in both fresh and stored asparagus. However, the soluble extract of total phenolics and flavonoids were minor and the missing significance of phenolics and flavonoids in antioxidant capacity of white asparagus spears depends on these small amounts.     

Endogenous microflora in turbid virgin olive oils and the physicochemical characteristics of these oils

Cloudy olive oil, the fresh olive juice, is an intermediate form before full precipitation of freshly produced olive oil. Some consumers prefer it because they consider it as more natural and less processed. The cloudy form can persist for several months. The oil is a sort of dispersion/suspension system which can be also described as a micro‐emulsion/suspension. Water micro‐droplets were found to have a size ranging from 1 to 5 µm. Cloudiness is due to the low water content and the presence of natural emulsifiers in the oil. The suspension is formed by solid particles (5–60 µm) deriving from the olive fruit. They are present in small amounts (12–460 mg/kg oil). In the newly produced olive oil, containing 0.17–0.49% water, a number of microorganisms of different types (bacteria, yeasts, moulds) were found to survive, but at very low concentrations (<3 log cfu/mL oil). They originate from the exterior of the fruit (epiphytic microflora) and their presence is considered natural. Their enzyme activities do not seem to affect the quality of the final product.     

Correction to: Classifying MOOC forum posts using corpora semantic similarities: a study on transferability across different courses

Neural Computing and Applications - A correction to this paper has been published: https://doi.org/10.1007/s00521-021-05904-z     

Segregation and conformational transitions in triblock copolymers in dilute solution: 3. Viscometric investigations in solvent mixtures

Viscometric measurements were carried out on a triblock copolymer PMMA/PS/PMMA at two temperatures in two binary solvent mixtures, in order to establish to what extent segregation between the two kinds of blocks is maintained as the composition of the solvent mixture i.e. its preferential affinity to one of the blocks, changes. From the variation of the limiting viscosity number of the polymer versus composition of the solvent mixture, taking into account the corresponding plots for the two homopolymers, it was established: that at relatively low temperature the molecular dimensions of the block copolymer are very close to those calculated neglecting the heterocontact interactions, i.e. assuming segregation, and that at higher temperatures the dimensions observed for the block copolymer are higher than the values calculated by assuming segregation, thus showing that the heterocontacts exert some influence, inducing the chain to expand. A comparison with a PS/PMMA random copolymer of the same composition showed, however, that in the same solvent mixtures the number of heterocontacts was far lower in the case of the block copolymer than in the case of the random copolymer, even at elevated temperatures.     

GaAs MMIC reliability studies

Three types of GaAs monolithic microwave integrated circuits (MMICs) were RF high temperature accelerated life tested to determine the median time before failure (MTBF). Life testing was performed under the d.c. bias conditions and RF input power levels the MMICs would be expected to use under actual operating conditions. the accelleration condition was to raise the base-plate temperature high enough to result in degradation in approximately 1000 hours at the highest test temperature. Because the MMICs were designed for power applications, the input signal level was large enough to cause approximately 1 dB compression. Device failure was defined as a 20 per cent decrease in output power as measured at 125°C, or room temperature when the temperature control system was turned off. Under these conditions the MTBF extrapolated to a channel temperature of 125°C varied between 8 × 10³ hours and 2 × 10⁵ hours depending on the MMIC type. The primary failure mode appeared to be surface leakage currents under the passivation layer.     

Cold storage,reconditioning potential and chip processing quality of spring potato (Solanum tuberosum L. cv. Hermes) tubers in response to differential nitrogen fertilisation

BACKGROUND: Crop management has been implicated in tuber sugar accumulation and potato processing quality. However, reports on potato postharvest behaviour, tuber composition and processing quality in response to crop nitrogen (N) fertilisation have been sparse and inconclusive. In this study, chipping potato cv. Hermes was treated with four preplanting N rates (0, 100, 200 and 300 kg ha^?1) to evaluate the effect of N fertilisation on sugar accumulation profiles and processing quality at harvest, after cold storage at 4.5 °C for up to 200 days and after reconditioning at 16 °C for 10–30 days. RESULTS: Preharvest leaf petiole analysis and tuber nitrate analysis at harvest confirmed crop response to N rates. At harvest, tuber specific gravity decreased marginally beyond 200 kg N ha^?1. Chip colour as well as tuber sucrose and reducing sugar (RS) content was unaffected by N fertilisation rate. During cold storage and reconditioning, tuber fresh weight loss and sprout growth were unaffected by N rate, while its effect on tuber sugar levels was either statistically or practically insignificant. Tuber sucrose and RS contents correlated highly with chip colour (r = ? 0.729, P <0.001 and r = ?0.791, P <0.001 respectively). Importantly, postharvest chip colour was also unaffected by N rate, though it declined markedly with the onset of cold storage and improved significantly throughout reconditioning. Differences in chip colour between years were limited but potentially critical in meeting the commercial standard. CONCLUSION: Completion of physiological crop senescence of the spring potato crop under Mediterranean climatic conditions seems to mitigate the potential interference of preplanting N fertilisation with tuber maturation and subsequently cold storage performance, reconditioning potential and processing quality. Copyright © 2009 Society of Chemical Industry     

Biochemistry of hydrogen metabolism in Chlamydomonas reinhardtii wild type and a Rubisco-less mutant

Sulfate nutrient-deprivation in Chlamydomonas reinhardtii   brings about prompt degradation of Rubisco and a concomitant substantial accumulation of starch. These changes precede hydrogen (_H2${\mathrm{H}}_2$) photoevolution by the cells. The cause-and-effect relationship between Rubisco loss, starch accumulation and subsequent _H2${\mathrm{H}}_2$-photoevolution in C. reinhardtii, and the role of illumination for these changes to occur, was investigated in this work. A Rubisco-less and acetate-requiring mutant of C. reinhardtii   (CC2653) was employed as a tool in this investigation and compared to the wild type (WT) in terms of protein and starch metabolic flux and _H2${\mathrm{H}}_2$-evolution upon sulfur deprivation. Results showed a prompt Rubisco degradation and concomitant 10-fold starch accumulation in the WT in the light, which was completed within 48 h of S-deprivation. This was followed by a regulated starch degradation and concomitant _H2${\mathrm{H}}_2$-photoevolution, which lasted for up to 120 h in S-deprivation. This massive flux of primary metabolites (protein and starch) did not occur in the dark in the WT, suggesting a strictly light-dependent and integrated process in metabolite rearrangement and _H2${\mathrm{H}}_2$-photoevolution in C. reinhardtii  . The Rubisco-less CC2653 mutant failed to accumulate starch upon S-deprivation in the light or dark and also failed to evolve _H2${\mathrm{H}}_2$ gas. These results suggested a temporal cause-and-effect relationship between the light-dependent catabolism of Rubisco and starch accumulation, and the subsequent ability of the cell to perform a light-dependent starch degradation and _H2${\mathrm{H}}_2$-photoevolution. The regulated starch breakdown in the light apparently provides the endogenous substrate that supports _H2${\mathrm{H}}_2$-evolution, both by feeding electrons into the plastoquinone pool in chloroplasts, and indirectly by sustaining mitochondrial respiration for the maintenance of anaerobiosis in the cell.     

A nomogram method for estimating the energy produced by wind turbine generators

A simple nomogram is constructed to estimate the power generated by a wind turbine generator (WTG) operated at near maximum efficiency using optimum tip-speed ratio between cut-in and rated wind speed, and at constant power using optimum pitch control between rated and cut-out wind speed. The nomogram is based on information that is readily available for commercial WTGs as well as some simple statistical quantities for the wind at the site. When the wind speed is described by a Weibull distribution, the power of a WTG is estimated in terms of three generalized non-dimensional parameters. When a Rayleigh distribution is employed only two parameters are necessary. A second nomogram is also developed for those less common cases where a small correction of the results of the first nomogram is needed. A mathematical analysis is presented which allows for the construction of single chart nomograms without sacrificing the necessary accuracy. Two application examples demonstrate the degree of accuracy achieved by the nomograms and the advantages they offer for parametric analyses as regards convenience and labor.     

Caricature generation utilizing the notion of anti-face

The production of caricatures is a particularly interesting field of art, because it aims to highlight the very essence of a given face. Caricature generation systems traditionally rely on two approaches: they either follow extracted rules through learning algorithms, or follow rules that were directly programmed by experts. This paper attempts to reduce the reliance on heuristic methods, by proposing a novel method that provides a set of well-defined rules, which can be put to use for the purpose of caricature generation. The method is based on the notion of anti-face in conjunction with unbiased distortions. In addition, we indicate the usefulness of the anti-face as a means to perceive, for our own sake, the degree to which our face seems peculiar to others. Finally, we deploy a reverse variant of the method in order to attain beautification.

     

Diacetoxyiodobenzene and bis(trifluoroacetoxy)iodobenzene as photoinitiators for cationic polymerisations

Summary It is shown that i-butyl vinyl ether, tetrahydrofuran, epichlorhydrin and cyclohexene oxide, which undergo typically cationic polymerisation, are polymerised by UV-irradiation in the presence of diacetoxyiodobenzene or bis(trifluoroacetoxy)iodobenzene.