High frequency in-core acousto-optic modulation of a suspended core optical fibre

The confinement of high frequency acoustic waves inside a suspended core fibre (SCF) is numerically investigated for the first time. A 500 μm long acoustic cavity, based on a four-hole SCF, is designed, simulated and evaluated by using the finite element method. The cavity is acoustically excited in the frequency range of 50 - 56 MHz and the induced displacements are integrated along the fibre. A standard single mode fibre is simulated under the same conditions for comparison. The results show strong Lamb acoustic modes oscillating in the silica bridges and overlapping in the SCF core at the resonance of 52.84 MHz. The induced displacement achieves a maximum in the core centre decaying to an almost null value in the cladding. The acoustic wave concentration in the SCF core is 13 times higher compared to the standard fibre, indicating a promising solution to overcome the frequency limitation of the current all-fibre acousto-optic devices. The modulation efficiency is increased without reducing the fibre diameter, making the devices more stable, fast and suitable to modulate all-fibre lasers

Degradation of oligomeric procyanidins and anthocyanins in a Tinta Roriz red wine during maturation

A young red Tinta Roriz wine was stored for three months at different temperatures (12, 22, 32, 42 degrees C) under anaerobic conditions and after adjusting the SO2 to 0, 50, 100 mg/l. Changes in wine phenolic composition, especially the procyanidins and anthocyanins were measured using HPLC reverse phase. Dimeric (B1, B2, B3, B4), galloylated dimeric (B1-3-O-gallate, B2-3O-gallate, B2-3'-O-gallate) and trimeric procyanidins (C1, T2) were quantified during the maturation of the red wine, and their losses were found to be logarithmic with time. Temperature exerts a marked influence on the progressive degradation of procyanidins, while the presence of SO, slows down the degradation. Comparing their activation energies the dimer procyanidins B1, B2 and B3 appear to be more stable to degradation while trimer T2 and B2-3-O-gallate are most reactive. Concerning the anthocyanins, the acylated monoglucosides degrade faster than the other monoglucosides and the p-coumaric acid acylated pigments disappear faster than the acetic acid acylated pigments

Novel memory-based sensory approach to assess large-scale typicality: the case of mainland Portugal red wines

Twenty professional wine experts were asked to describe their prototypical construct of a representative young red wine from each of the 12 Protected Geographical Indications (PGI) of mainland Portugal. No samples were assessed; the experiment was based on memory alone by completion of 12 extended self-reported sensory questionnaires. Four large-scale areas were differentiated, the typicality being statistically validated and described from a sensory standpoint. Alcohol, acidity, bitterness, and astringency were cross-linked; the respective variations were correlated with published literature and expressed as key factors for the regional macroscale area differentiation. Bitterness and astringency were found to be sensory different and related on a geographical scale, as bitterness was primarily affected by inland/coastal influence; while astringency confirmed its customary north/south dependence that finding is to be considered a new understanding. Moreover, with the proposed methodology, it was possible to achieve a novel nationwide sensory characterization of PGIs, overcoming present day limitations on macroscale sensory research and sample representativeness. Results by uncalibrated prototypical memory assessment of single PGI Beira Atlântico were compared with the outcome of calibrated wine sampling assessment by local experts, using the same sensory questionnaire, and were found significantly correlated. The need for a calibration stage was found uneven regarding the overall group of scrutinized wine descriptors

Evolution of proanthocyanidins in bunch stems during berry development (Vitis vinifera L.)

Proanthocyanidins from bunch stems of two red varieties (Castelao Frances and Touriga Francesa) and one white variety (Viosinho)(Vitis vinifera L,) harvested in 1998, were separated into monomers (catechins), oligomers (degree of polymerization ranging from 2 to 12-15) and polymers (degree of polymerization >12-15), and then quantified during grape development (40 d before veraison until ripening). In addition, low molecular weight catechins [(+)-catechin and (-)-epicatechin], dimeric procyanidins (B1, B2, B3, B4), galloylated dimeric procyanidins (B13-0-gallate, B2-3-0-gallate, B2-3'-0-gallate), and trimeric procyanidins (C1, T2) from grape stems were quantified by HPLC, At harvest the polymeric fraction was the most abundant (28.0 - 35.8 mg . g-1 stem). For the three grape varieties, the content of catechins, oligomeric and polymeric fractions decreased during berry development mainly after veraison, Crape stems are also an important source of proanthocyanidins in the grape cluster when compared to the flavanol content in seeds. From an industrial point of view, stems seem to be an important source of proanthocyanidins for potential use as nutriceutical, enological products, chemical standards or even in winemaking to regulate flavanol composition in wine.

Evolution of anthocyanins during grape maturation of two varieties (Vitis vinifera L.), Castelao Frances and Touriga Francesa

Research Not

An analysis of the potentialities of portuguese vernacular architecture to improve energy efficiency

Vernacular architecture is characterised by a type of formal expression that has been developed in response to a number of factors â climatic, lithologic, cultural and economic â characterising the local area or region. In its various forms, a range of techniques has been employed in different regions to mitigate the effects of climate. Despite the fact that Portugal is a small country, it has a territory full of contrasts, which gave origin to many different architectural manifestations. The approaches adopted in the design and construction of vernacular buildings have the potential for further development and could be adapted in response to contemporary needs. In the future, a blend of tradition and modernity should be aimed at in order to develop a new form of aesthetics and functional construction. Portuguese vernacular architecture is associated with a fund of valuable knowledge that should be studied and aligned with the principles of sustainability. In this paper, is presented the climatic contrast between the northern and southern parts of Portugal and the relation with the purpose of different passive solar techniques used in vernacular architecture to provide comfort. The focus is on the effectiveness of passive cooling techniques (e.g. high thermal inertia, the use of light colours and patios), and the findings of a case study in which the thermal performance during the summer of a vernacular residential building located in the south of Portugal are presented. In the context of the current global drive for clean energy and sustainable buildings, much can be learned from a review of past experience in order to provide an understanding of such forms of construction, which are an intrinsic feature of specific places and have evolved over time in the face of a lack of resources

Procyanidin composition of Chardonnay, Mauzac and Grenache blanc grapes

Dimer procyanidins, galloylated or not, and trimers were analysed in three white grape varieties: Chardonnay, Mauzac and Grenache blanc. Procyanidins were extracted from the different components of the grape cluster (seeds, stems, skins and pulps) and then quantified by HPLC. Procyanidin B1 is the major component in stems and skins while procyanidin B2 is the major component in seeds

Dimer and trimer procyanidins in Carignan and Mourvèdre grapes and red wines

Dimer procyanidins, galloylated or not, and trimers were analysed in the red grapes Carignan and Mourvedre. Procyanidins were extracted from the various parts of the grape bunch and then quantified by HPLC. In Carignan and Mourvedre grapes, procyanidin B2 was the major component in seeds, whereas procyanidin B1 was the major component in stems and skins. Trimeric procyanidins were also present in grapes in larger amounts. Various red wines were produced from Carignan and Mourvedre grapes, using different winemaking procedures: entire crushed harvest, destemmed harvest, carbonic maceration and heating of the harvest. Entire crushed harvest gave red wines with the highest levels of procyanidins. An important release of procyanidins, especially procyanidin B1 from skins and stems, when present, occurred.Procyanidines dimères et trimères des raisins et vins rouges de Carignan et MourvèdreDes procyanidines dimères galloylées et non-galloylées, et trimères sont dosées dans deux cépages rouges: Carignan et Mourvèdre. Les procyanidines sont extraites des différentes parties de la grappe puis quantifiées par CLHP en phase inverse. Dans le raisin de Carignan et de Mourvedre, la procyanidine B2 est la plus abondante dans les pepins, tandis que la procyanidine B1 est la plus abondante dans les rafles et pellicules. Les procyanidines trimères sont aussi présentes en quantités importantes. Différents vins rouges ont été élabores à partir des cépages Carignan et Mourvèdre, en utilisant plusieurs téchniques de vinification: vendange foulée; vendange éraflée, macération carbonique et le chauffage de la vendange. Les quantités les plus abondantes de procyanidines sont obtenues dans des vins issus d'une vendange entière et foulée

Research Note: Effect of Light Quality on Fruit Growth, Composition and the Sensory Impact of the Wines

The stage at which grapes are harvested has an influence on the aromatic and phenolic composition of the berries and the resulting wines. The aim of this study was to evaluate wines harvested sequentially as outlined in the berry sugar accumulation model. Two vintages and treatments in which the light qualityand quantity were altered at the fruit zone were compared. In 2010/2011, the grapes were harvested at two ripening stages after the sugar loading plateau was reached, namely the “fresh fruit” stage (20-25 days afterwards) and “pre-mature” stage (at approximately 35 days). In the 2011/2012 season, grapes were harvested 45 days after the sugar loading plateau was reached (the “mature fruit” stage). Vegetative aromas were synonymous with the “fresh fruit” stage in 2010/2011, while the 2011/2012 wines from the “mature fruit” harvest date were characterized by raisin, prune and spicy aromas. In both seasons, the control treatments were rated more intense in ‘satin in the mouth’ in and after expectoration. Wines in which the UV-B radiation was excluded during berry growth were rated the highest in the mouthfeel attribute ‘coarseness’ in both treatment seasons. Wines were analyzed chemically for phenolic content using HPLC, and sensorial using descriptive analysis with a trained panel. In the leaf removal treatments,higher acidity content enhanced the perception of astringency in the wine. Wines were analyzed chemically for phenolic content using HPLC and sensorial using descriptive analysis with a trained panel. Overall, the data showed that grape composition was altered by varying light quality, within a season, but seasonalvariation overrode treatment effects. Flavonol concentration in 2011/2012 wine was higher in the exposed leaf removal treatment compared to the other treatments. High light intensities in 2011/2012 season increased anthocyanin concentration in the wine.. This study emphasizes the importance of the quality and quantity of light on the composition and quality of wines, and presents new findings regarding sensory attributes associated with harvesting at different ripening stages.

Detailed spatial-spectral numerical characterization of axially symmetric broadband ultrasonic resonances in standard optical fibers

Standard single mode optical fibers (SMFs) have been widely employed to generate and measure ultrasonic signals in remarkable applications. In particular, optoacoustic fiber sensors provide unique features for microscale high resolution ultrasound imaging in biomedicine. However, at specific resonance frequencies, SMFs work as acoustic filters inducing relevant geometrical attenuation bands higher than 10 dB, which limit the sensors’ sensitivity and frequency operation, causing image distortions and artifacts. We have numerically demonstrated high frequency axially symmetric ultrasonic resonances inside an optical fiber for the first time. The propagation of resonant axially symmetric acoustic modes along 1 cm fiber is investigated by means of 2D and 3D finite element techniques up to 80 MHz. The dispersion of the modes and induced beatlengths are characterized from the complex multimode interference with the 2D Fourier transform. The simulated spectra are validated with the renowned Pochhammer-Chree analytical equations. The frequency response of the acoustically induced strains in the fiber core is evaluated, and important acoustic parameters relevant for the modulation of phase, wavelength and power in optical fibers and diffractive gratings are derived and discussed. The results show that these resonances are strongly dependent on the modal beatlengths. Solutions to improve the operation of fiber-based devices are proposed, pointing out new alternatives to advance broadband optoacoustic sensors and monolithic acousto-optic modulators