Experimental test of a trace formula for two-dimensional dielectric resonators

Resonance spectra of two-dimensional dielectric microwave resonators of circular and square shapes have been measured. The deduced length spectra of periodic orbits were analyzed and a trace formula for dielectric resonators recently proposed by Bogomolny et al. [Phys. Rev. E 78, 056202 (2008)] was tested. The observed deviations between the experimental length spectra and the predictions of the trace formula are attributed to a large number of missing resonances in the measured spectra. We show that by taking into account the systematics of observed and missing resonances the experimental length spectra are fully understood. In particular, a connection between the most long-lived resonances and certain periodic orbits is established experimentally.Comment: 14 pages, 12 figures, 1 tabl

Modulating the bitterness of Empeltre olive oil by partitioning polyphenols between oil and water phases: Effect on quality and shelf life

Bitterness is a positive sensorial attribute of olive oil that mainly depends on phenol concentration. However, excessive bitterness may be unpleasant for consumers. The aim of this investigation was to evaluate if partitioning polyphenols between oil and water phases could modulate the bitterness of an Empeltre olive oil containing a phenolic concentration higher than the typical content for this olive oil variety. The linear relationship observed between the percentage of oil in the extraction system and the percentage of phenols removed from the oil permitted estimating the olive oil-to-water ratio required to reduce the concentration of phenols for a given value in order to modulate Empeltre olive oil bitterness. Olive oils after liquid–liquid extraction did not develop any negative sensory attributes, and their physicochemical parameters were not substantially affected. Liquid–liquid extraction using water as a solvent is a procedure capable of effectively reducing the total phenol compounds of Empeltre extra virgin olive oil and, as a consequence, of reducing its bitterness intensity without affecting the highest commercial category determined by the parameters legally established by European Community regulations just after extraction and during nine months of storage

Potential of a new strain of Bacillus amyloliquefaciens BUZ-14 as a biocontrol agent of postharvest fruit diseases

The biocontrol potential of the Bacillus amyloliquefaciens strain BUZ-14 was tested against the main postharvest diseases of orange, apple, grape and stone fruit. After characterizing the temperature and pH growth curves of strain BUZ-14, its in vitro antifungal activity was determined against Botrytis cinerea, Monilinia fructicola, M. laxa, Penicillium digitatum, P. expansum and P. italicum. Subsequently, in vivo activity was tested against these pathogens by treating fruit with cells, endospores and cell-free supernatants. The in vitro results showed that BUZ-14 inhibited the growth of all the pathogens tested corresponding to the least susceptible species, P. italicum, and the most susceptible, M. laxa. In vivo tests corroborated these results as most of the treatments decreased the incidence of brown rot in stone fruit from 100% to 0%, establishing 107 CFU mL-1 as the minimum inhibitory concentration. For the Penicillium species a preventive treatment inhibited P. digitatum and P. italicum growth in oranges and reduced P. expansum incidence in apples from 100% to 20%. Finally, it has been demonstrated that BUZ-14 was able to survive and to control brown rot in peaches stored at cool temperatures, making it a very suitable biocontrol agent for application during the post-harvest storage and marketing of horticultural products

The evolution of Arbequina olive oil quality during ripening in a commercial super-high density orchard in north-east Spain

The objective of this work was to follow the maturity of the olives in a commercial Arbequina super-high density orchard and to study the evolution of the olive oil quality. For this objective, the physicochemical, nutritional and sensory parameters were studied. The free acidity was found to be similar during ripening whereas the peroxide index and K232, K270 decreased. The total phenol content and oxidative stability showed a similar trend. First, it increased and then decreased. alpha-tocopherol, saturated fatty acid and pungency decreased. The polyunsaturated content increased while the MUFAS/PUFAS ratio decreased. In 2010, the crop maturity was quicker, and the maturity indexes were higher than in the 2009 crop for the same picking date. Even in the same orchard, the maturity is changing in each crop season. For this reason, it is necessary to choose the optimal harvesting date

Self-Tuning PID controller for autonomous car tracking in urban traffic

In this paper an on line self-tuned PID controller is proposed for the control of a car whose goal is to follow another one, at distances and speeds typical in urban traffic. The bestknown tuning mechanism is perhaps the MIT rule, due to its ease of implementation. However, as it is well known, this method does not guarantee the stability of the system, providing good results only for constant or slowly varying reference signals and in the absence of noise, which are unrealistic conditions. When the reference input varies with an appreciable rate or in presence of noise, eventually it could result in system instability. In this paper an alternative method is proposed that significantly improves the robustness of the system for varying inputs or in the presence of noise, as demonstrated by simulation

Changes in the Physicochemical and Nutritional Parameters of Picual and Arbequina Olive Oils during Frying

Deep fat frying is an important cooking process in Mediterranean countries. Olive oil is a very convenient fat to use for this culinary purpose. The chemical composition of olive oils differs from edible oils in terms of fatty acid and antioxidant compounds that gives olive oil its greater stability. The aim of this work was to describe the stability of Picual and Arbequina olive oil during deep frying of frozen potatoes in comparison with high oleic sunflower oil. Changes in different physicochemical and nutritional parameters were studied during frying. Picual olive oil had a higher stability in comparison with high oleic sunflower oil and Arbequina olive oil. Picual olive oil is very suitable for frying because it is able to undergo the greatest number of frying cycles without exceeding the limits allowed by regulations. This behavior is due to its phenolic content, the lower loss in tocopherol and better stability. Practical Applications: The information gained from this research could be very appropriate for consumers and for the industry to know which variety of olive oil is more suitable for frying longer frying cycles without exceeding the limits allowed by regulation and remain in good quality

Effect of modified atmosphere packaging (MAP) and UC-C irradiation on postharvest quality of red raspberries

Red raspberries (Rubus idaeus L.) are highly appreciated by consumers. However, their postharvest shelf life scarcely exceeds 5 d under the refrigeration temperatures usually applied during commercialization, due to their high susceptibility to dehydration, softening and rot incidence. Thus, the objective of this study was to investigate the ability of UV-C radiation (UV1: 2 kJ m-2 and UV2: 4 kJ m-2 ), passive modified atmosphere packaging (MAP) with transmission rates (TR) for O2 and CO2 of 1805 mL d-1 and 1570 mL d-1 (MAP1), and 902 mL d-1 and 785 mL d-1 (MAP2), respectively, and the combination of both technologies to prolong raspberries’ shelf life at 6¿ C. Their influence on respiration, physicochemical parameters, and microbiological and nutritional quality was assessed during 12 d of storage. The combination of 4 kJ m-2 UV-C radiation and a packaging film with O2 and CO2 transmission rates of 902 mL d-1 and 785 mL d-1, respectively, produced a synergistic effect against rot development, delaying senescence of the fruit. The UV2MAP2 and MAP2 samples only showed 1.66% rot incidence after 8 d of storage. The UV2MAP2 samples also had higher bioactive content (1.76 g kg-1 of gallic acid equivalents (GAE), 1.08 g kg-1 of catechin equivalents (CE) and 0.32 g kg-1 of cyanidin 3-O-glucoside equivalents (CGE)) than the control samples at the end of their shelf life. Moreover, the mass loss was minimal (0.56%), and fruit color and firmness were maintained during shelf life. However, the rest of the batches were not suitable for commercialization after 4 d due to excessive mold development. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Efficiency of the cathode protection inthe sports crafts, fishing and cabotage boats

This paper studies the efficiency of sacrificial anodes in nautical engineering, marine and maritime. The anode design, quality manufacturing process and proper installation are critical processes for maximum protection of equipment and vessels. The damage, which causes corrosion, can be reduced; can even be avoided by protection methods economically profitable. The predictable future savings will come by the correct use of the current state of knowledge. This acquired knowledge is not always used rationally despite the great progress and current knowledge we have about the physical-chemical corrosion phenomena. Aspects relating to the assembly, distribution and support must be optimized for optimum performance and facilities are properly protected. Determine guidelines to consider in the design of the equipment (compatibility and incompatibility of the materials), the manufacturing quality of the elements to prevent galvanic corrosion, as in the embodiment of different patterns of maintenance in the case of pleasure craft, fishing boats and coastal represent very substantial costs and losses of the life of the vessels and their vital components.Postprint (published version