Chromatic Characteristics Research Articles

Er3+-doped SiO2-based glasses – An exploration of structural, visible, chromatic, and NIR fluorescence characteristics

SiO2-based glasses doped with 1 mol% Er3+ were fabricated via melt-quench process and their structural and visible and NIR (near-infrared) fluorescence features have been investigated. Calculated Judd–Ofelt (J–O) intensity parameters that were deduced from absorption spectra are applied to reckon different radiative factors. Visible emission spectra and decay profiles (for 4S3/2 → 4I15/2 transition) were registered upon λexci.= 379 nm. CIE (Commission International de I'Eclairage), CCT (correlated color temperature), and CP (color purity) values were evaluated from the emission spectra. Also, a NIR luminescence band (4I13/2 → 4I15/2 transition) was identified by 980 nm LD (laser diode). Later, emission cross-section [(σemi) stimulated, (σMemi) from Mccumber theory] values were computed for observed NIR emission. Highest σemi and gain bandwidth (σemi × ∆λeff) were obtained to be 9.18×10−21 cm2 and 517×10−28 cm3 accordingly for 4I13/2 → 4I15/2 transition.

Data-Driven Convolutional Model for Digital Color Image Demosaicing

Modern digital cameras use specific arrangement of Color Filter Array to sample light wavelength corresponding to visible colors. The most common Color Filter Array is the Bayer filter that samples only one color per pixel. To recover the full resolution image, an interpolation algorithm can be used. This process is called demosaicing and it is one of the first processing stages of a digital imaging pipeline. We introduce a novel data-driven model for demosaicing that takes into account the different requirements for reconstruction of the image Luma and Chrominance channels. The final model is a parallel composition of two reconstruction networks with individual architecture and trained with distinct loss functions. In order to solve the overfitting problem, we prepared a dataset that contains groups of patches that share common chromatic and spectral characteristics. We reported the reconstruction error on noise-free images and measured the effect of random noise and quantization noise in the demosaicing reconstruction. To test our model performance, we implemented the network on NVIDIA Jetson Nano, obtaining an end-to-end running time of less than one second for a full frame 12 MPixel image.

Micro-oxygenation level as a key to explain the variation in the colour and chemical composition of wine spirits aged with chestnut wood staves

A deep knowledge of oxygenation level effect on wine spirits' ageing is imperative to understand ageing chemistry and to select the most suitable technological option towards quality and sustainability. Following two articles on the same trial, this work focused on colour, total phenolic index (TPI) and basic chemical characteristics of a wine spirit aged in 50 L demijohns with chestnut wood staves together with three micro-oxygenation (MOX) levels. Chromatic characteristics and TPI were monitored over time (8–365 days) while sensory colour, alcoholic strength, acidity, pH and dry extract were assessed at the end of ageing. Results showed that stronger oxygenation promoted significantly faster colour evolution (lower lightness, higher chroma, red, yellow and brown hues) and higher TPI than mild and intermediate oxygenation until 60 days, probably by favouring the leaching of outer wood layers and extraction/degradation of tannins. No significant differences were found between these ageing modalities at 365 days. Outcomes suggest that the stronger MOX is the most suitable modality in terms of quality and sustainability. Significant differences between wine spirits resulting from MOX and control modality (slower colour evolution, lower TPI and dry extract) confirms the oxygen pivotal role in wine spirit's ageing, particularly in the colour evolution.

Revisiting the use of pectinases in enology: A role beyond facilitating phenolic grape extraction

With the objective of improving both the extraction of phenolic compounds from grapes and their maintenance in the final wine, we compared the effect of favoring phenolic extraction with a pectolytic-based maceration enzyme with that of favoring both phenolic extraction and the partial elimination of the suspended material using a pectolytic-based clarification enzyme. The phenolic composition of the final wines and those adsorbed to the precipitated lees were analyzed. Both enzymes increased wine color intensity and phenolic content, but the best results were observed when the clarification enzyme was used. This enzyme generated the largest losses of phenolics bound to precipitated lees. However, this resulted in a positive effect, the precipitation of lees rich in phenolic compounds probably created a pronounced gradient of phenolic compounds from grapes to must/wine and better chromatic characteristics in the final wine, compared with the wine made using a traditional maceration enzyme.

Combination of methods as alternative to maintain the physical-chemical properties and microbiological content of hass avocado pulp during storage

Avocado is a fruit with great nutritional value; however, it is highly perishable, reaching in Colombia around 40% postharvest losses. The evaluation of using non-conventional technologies to process fruits and vegetables, like ultraviolet light irradiation, use of antioxidant solutions, and packaging in modified atmospheres constitute an alternative to lengthen the shelf life of perishable foods.This research evaluated irradiation at three times, reaching up different irradiation levels, all of them below the maximum permitted for fruits and vegetables. The pH and total soluble solids content of the samples showed variations due to storage at 4 °C, without being affected by the application of ultraviolet light. The chromatic characteristics showed important variations due to maturation and senescence processes in fruits. Application of the highest dose evaluated (20.32 kJ * m−2) in combination with antioxidant solution had the best results on texture and color. Likewise, greater reduction was observed in the fruit's initial microbial load and inhibition of its development during the storage time. Samples with UV treatment and packaged in modified atmosphere had the best behavior in chromatic parameters (L*, a*, b*) and soluble solid content (°Brix). Using combined mechanisms contributes to extending the shelf life of perishable foods, representing an alternative to generate added value to the crop and diminish losses in its postharvest.

Reducing the Negative Effect on White Wine Chromatic Characteristics Due to the Oxygen Exposure during Transportation by the Deoxygenation Process.

In white wine production, a great effort is made to avoid extensive contact with oxygen, which might adversely affect color and aroma. In this work, the impact of bulk transportation on white wine oxygen uptake and the effect of deoxygenation on white wine dissolved oxygen levels, as well on the phenolic composition and chromatic characteristics of white wines stored for nine months, were studied. Transportation increased the white wine dissolved oxygen content (117 and 181% in the wines studied) that increased the free sulfur dioxide loss during storage. Moreover, deoxygenation of white wines reduced the increase in the yellow color of white wines during storage, probably related to the higher levels of free sulfur dioxide that remain in these wines during storage. Furthermore, the amount of wine phenolics also have a decisive influence on wine color characteristics evolution, with increased levels of total phenolic compounds increasing the variation in the b *(measure of yellowness) values of the wines after nine months of storage. Results show the negative impact of bulk transportation on white wine color characteristics; however, wine deoxygenation is a good practice to minimize those aspects, preserving color characteristics.

Quality, Nutritional, Volatile and Sensory Profiles and Consumer Acceptance of Fondillón, a Sustainable European Protected Wine

Sustainable irrigation strategies in Southeast Spain (one of the most arid regions in Europe) are essential to fight against desertification and climate change mitigation. In this way, Fondillón production is based on rain-based vineyards, over-ripe Monastrell grapes, and non-alcohol fortification. Thus, Fondillón is a naturally sweet red wine, protected within the Alicante Denomination of Origin, recognized by the European Union in its E-bachus database. The study aim was to evaluate the effect of the aging (solera factor) on Fondillón: (i) basic enological parameters (e.g., total, and volatile acidity), (ii) chromatic characteristics, (iii) antioxidant activity (ABTS•+, FRAP and DPPH•), (iv) total contents of condensed tannins and anthocyanins, (v) volatile composition, (vi) sensory profile, and (vii) overall liking. Experimental data proved that the wine (1960 solera) with the highest total contents of condensed tannins and anthocyanins and total antioxidant activity was the most liked by Spanish consumers. Experimental results clearly established a positive relationship among Fondillón chemical composition, its antioxidant activity, and overall consumer liking. Exceptional harvest with grapes having extremely high antioxidant power (e.g., 1960 solera) will result, even more than 50 years later, in high quality wines with high consumer acceptance and a high monetary worth.

Sea Buckthorn Leaf Powders: The Impact of Cultivar and Drying Mode on Antioxidant, Phytochemical, and Chromatic Profile of Valuable Resource.

Sea buckthorn (Hippophae rhamnoides L. (HR)) leaf powders are the underutilized, promising resource of valuable compounds. Genotype and processing methods are key factors in the preparation of homogenous, stable, and quantified ingredients. The aim of this study was to evaluate the phenolic, triterpenic, antioxidant profiles, carotenoid and chlorophyll content, and chromatic characteristics of convection-dried and freeze-dried HR leaf powders obtained from ten different female cultivars, namely ‘Avgustinka’, ‘Botaniceskaja Liubitelskaja’, ‘Botaniceskaja’, ‘Hibrid Percika’, ‘Julia’, ‘Nivelena’, ‘Otradnaja’, ‘Podarok Sadu’, ‘Trofimovskaja’, and ‘Vorobjovskaja’. The chromatic characteristics were determined using the CIELAB scale. The phytochemical profiles were determined using HPLC-PDA (high performance liquid chromatography with photodiode array detector) analysis; spectrophotometric assays and antioxidant activities were investigated using ABTS (2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) and FRAP (ferric ion reducing antioxidant power) assays. The sea buckthorn leaf powders had a yellowish-green appearance. The drying mode had a significant impact on the total antioxidant activity, chlorophyll content, and chromatic characteristics of the samples; the freeze-dried samples were superior in antioxidant activity, chlorophyll, carotenoid content, and chromatic profile, compared to convection-dried leaf powder samples. The determined triterpenic and phenolic profiles strongly depend on the cultivar, and the drying technique had no impact on qualitative and quantitative composition. Catechin, epigallocatechin, procyanidin B3, ursolic acid, α-amyrin, and β-sitosterol could be used as quantitative markers in the phenolic and triterpenic profiles. The cultivars ‘Avgustinka’, ‘Nivelena’, and ‘Botaniceskaja’ were superior to other tested cultivars, with the phytochemical composition and antioxidant activity.

Non-destructive assessment of quality parameters of white button mushrooms (Agaricus bisporus) using image processing techniques.

Considering that appearance of white button mushroom (WBM) as the trigger for registering its quality, this study was aimed at analyzing the visual cues by the application of image processing tools. While L-a-b colour space and skewness was used for estimating chromatic and morphological characteristics; onset of discolouration of WBM was predicted by hyperspectral image analysis. Undamaged (UD) and damaged (D) mushrooms were stored under refrigerated conditions (3-5°C and 90% Rh). RGB and hyperspectral images were acquired on alternate storage days 1, 3, 5, 7 and 9. Weight loss, texture and moisture content of stored mushrooms were also recorded during the storage period. Colour changes in stored UD and D were found to be in b (21.55) and a (2399) value, respectively. Browning index in D was 83-212% higher than UD mushrooms across the storage period. Weight and firmness losses in D were higher by 65.9 and 31.4%, respectively than UD. Morphological characteristic in terms of aspect ratio and roundness were not found to vary significantly over the storage period for both UD and D mushrooms. Chemometrics revealed that multiplicative scatter correction was the best pre-processing tool and that onset on discolouration is conspicuous in the spectral region of 520-800nm. k-NN fared better than PLS-DA for correct classification (100%) of UD and D mushrooms.

Effect of Barrel-to-Barrel Variation on Color and Phenolic Composition of a Red Wine.

Tangible variation of sensory characteristics is often observed in wine aged in similar barrels. Barrel-to-barrel variation in barrel-aged wines was investigated in respect of the most important phenolic compounds of oenological interest. A red wine was aged in 49 medium-toasted oak (Quercus petraea) barrels, from four cooperages, for 12 months. The resulting wines were evaluated for chromatic characteristics, anthocyanin-related parameters, total phenols, flavonoids and non-flavonoids phenols, flavanol monomers, and oligomeric and polymeric proanthocyanidins. PCA and ANOVA were applied to investigate the relationships between barrels and to assess cooperage and individual barrel effect. Three cooperages influenced the wine similarly during aging. Anthocyanin-related parameters showed the highest variation, 25–37%, other phenolics varied 3–8.5%, and with two exceptions, chromatic characteristics changed 1.7–3%. The relationship between the number of barrels and the expected variation for each analytical parameter was calculated, as reference for future measurements involving barrel lots, either in wine production or experimental design.

Enhancement of anthocyanin and chromatic profiles in 'Cabernet Sauvignon' (Vitis vinifera L.) by foliar nitrogen fertilizer during veraison.

The influence of foliar nitrogen fertilizer during veraison (FNFV) on anthocyanin accumulation and chromatic characteristics of 'Cabernet Sauvignon' grapes over two seasons was investigated. Urea and phenylalanine fertilizers (TU and TP, respectively) and a control were sprayed three times at veraison. In 2018, TU displayed a significant enhancement in total individual anthocyanin content and a* and Cab * profiles. In 2019, FNAV significantly improved the content of total non-acylated, acylated anthocyanin and total individual anthocyanin, and the profiles of L*, a* and Cab *, except a* in TU. The whole process from phenylalanine variation to anthocyanin accumulation in grape skins was analyzed. On the whole, after the first FNFV to harvest, the increase in phenylalanine metabolism, abscisic acid content, effects of PAL (Phenylalanine ammonia lyase), UFGT (UDP glucose-flavonoid 3-O-glucosyltransferase) and transcript concentrations of VvPAL and VvUFGT involved in anthocyanin biosynthesis were also strong evidence explaining the increased anthocyanin and chromatic profiles in 2019. Overall, FNFV for nitrogen-deficient grapevines could significantly improve grape color, especially in the 2019 veraison with a proper climate. © 2021 Society of Chemical Industry.

Digitized optofluidic element and its application to tristate lens for presbyopia correction

Current optofluidic devices are analog focus-tunable elements with a continually varying focus between foci. An innovative digitized optofluidic element was developed to enable fast switching between the foci. The operation involves an internally placed elastic membrane of changing shape between the refractive and diffractive forms with a tiny amount of fluid transfer by a micro-actuator. This allows for switching the digitized optofluidic element between the refractive and diffractive states of the preset optical powers. A multimodal relief surface design was used in the diffractive state to manage the diffractive grooves and improve the chromatic characteristics. We applied finite element analysis to establish the membrane mechanical properties. The proof-of-concept prototypes were made using material bonding fabrication processes and were used to demonstrate an elastic membrane shape change between the refractive and diffractive forms for switching between the corresponding optical states. The design of the digitized optofluidic element allowed for bistate or tristate switching by a single actuator. The switchable element can be fairly thin, enabling conversion of a fixed lens into a dynamic lens switchable between two or three foci. The application of the tristate design to eyewear for presbyopia correction is discussed.

The Management of Dissolved Oxygen by a Polypropylene Hollow Fiber Membrane Contactor Affects Wine Aging.

Background: Numerous oenological practices can cause an excess of dissolved oxygen in wine, thus determining sensory and chromatic defects in the short- to long-term. Hence, it is necessary to manage the excess of oxygen before bottling. Methods: In this study, the management of the dissolved oxygen content by a polypropylene hollow fiber membrane contactor apparatus was performed in two wines from different grape varieties (Aglianico and Falanghina). The wines were analyzed after an 11-month aging. Anthocyanins and acetaldehyde content were evaluated by HPLC. In addition, other phenolic compounds and chromatic characteristics were analyzed by spectrophotometric methods. NMR and HR ESIMS analyses were conducted to evaluate the amount of pyranoanthocyanins and polymeric pigments. Results: After 11 months of aging, in both wines a decrease of free and total SO2 with respect to initial values was detected. In the wines with the highest dissolved oxygen levels, a more remarkable loss was observed. No significant differences in terms of color parameters were detected. In red wine with the highest oxygen content, a massive formation of polymeric pigments and BSA reactive tannins was observed, as opposed to wines with lower oxygen levels. Conclusion: The study demonstrated that the membrane contactor can prove a successful tool to manage dissolved oxygen in wines as to prevent their oxidative spoilage.

Impact of micro-oxygenation timing and rate of addition on color stabilization and chromatic characteristics of cabernet sauvignon wines

The presented study evaluated anthocyanins, anthocyanin-derived pigments and chromatic characteristics of six micro-oxygenation treatments resulting from applying oxygen at different times and rates. Oxygen was applied before malolactic fermentation (MLF) at a rate of zero or 20 mg O2/L/month and after MLF at rates of zero, 4.5 or 9 mg O2/L/month. LC-MS analysis after 6 months of bottle aging indicated that the formation of anthocyanin-derived compounds was related to the acetaldehyde (ACH) levels. When observing an increase in the level of ACH, formation of compounds was enhanced in which ACH was involved as B-type vitisins. Otherwise, where ACH was not involved, compounds as A-type vitisins, pinotins and direct adducts, were formed. Although the wine was filtered after MLF, only a marginal increase in the ACH concentration was observed during post-MLF MOX. This increase occurred only in wines that had previously received pre-MLF MOX. When MOX was applied at both moments and highest rates, wines produced a higher yellow color component (b*) and hue (hab) than the rest of the wines. These CIELab parameters were highly correlated with flavanyl-pyranoanthocyanins. These results suggest that in order to stabilize wine color, it is recommended to apply MOX before and after MLF.

Photoluminescence, optical transition properties and temperature-induced shift of charge transfer band and temperature sensing property of GdNbTiO6: Sm3+ phosphors

GdNbTiO6: Sm3+ phosphors with various Sm3+ concentrations were prepared via a high temperature solid-state reaction method. The crystal structure of the samples was characterized by means of X-ray diffraction (XRD) and the as-prepared samples were confirmed to be orthorhombic phase GdNbTiO6. Photoluminescence properties were investigated by measuring the concentration- and temperature-dependent photoluminescence spectra. Concentration-dependent luminescence quenching and luminescent thermal quenching behaviors were observed and they were respectively ascribed to the electric dipole-dipole interaction between Sm3+ ions and the cooperation of energy transfer and crossover process. The chromatic characteristics were found to be dependent on the excitation wavelength and Sm3+ concentration. In addition, temperature-induced redshift of charge transfer band of GdNbTiO6 host was found in temperature-dependent excitation spectra and the opposite variations of different excitation peaks were utilized for optical thermometry. Finally, the optical transition property was studied on the basis of the diffuse reflectance spectra and Judd-Ofelt (J-O) theory, meanwhile, its accuracy was evaluated by the result of emission spectra.

Efficiency of carboxymethylcellulose in red wine tartaric stability: Effect on wine phenolic composition, chromatic characteristics and colouring matter stability

In this work, the effect of carboxymethylcellulose structural features on the efficiency to prevent potassium hydrogen tartrate precipitation in red wines and on the phenolic composition, chromatic characteristics and colouring matter stability was studied. The degree of substitution of carboxymethylcellulose was important for its efficiency in highly unstable wines. Application of carboxymethylcellulose doesn’t result in a significant change in the phenolic, monomeric anthocyanin composition, colour intensity, and chromatic characteristics of red wines. Sensory analysis also showed that carboxymethylcellulose doesn’t have a significant impact on wine sensory attributes. Carboxymethylcellulose doesn’t decrease the colouring matter stability. The use of turbidity for evaluating the colouring matter stability of wines has severe drawbacks as the turbidity value measured might not be related to the amount of suspended material. Therefore, the application of carboxymethylcellulose in red wines is efficient in increasing tartaric stability without impacting on the phenolic composition, sensory characteristics, and colouring matter stability.

Surface Discharge Status Diagnosis Based on Optical Image Chromaticity Coordinates

The physical and chemical processes of surface discharge are more complicated than other discharge forms due to the influence of gas composition and dielectric properties. Spectral diagnosis can be used to analyze the main species in the discharge process. However, the chromaticity characteristics are the comprehensive representation of all emission spectra. This article presents a new method to diagnose the state of surface discharge using chromaticity coordinates in color space. It is observed that the chromaticity coordinates slide along a straight line between the equal energy white point and a specific spectral color with the development of surface discharge. The relative position of the chromaticity coordinates on the line indicates the different states of the surface discharge. The slope of the line is affected by the material characteristics while external factors such as the camera's exposure time and the color of materials have no effect on it. It is found that the slope of the chromaticity coordinate curve has a fixed range, which means that there exists a specific color space of surface discharge. Finally, the effects of the ambient noise are corrected. This method uses the chromaticity coordinates in a long time scale to diagnose the microscopic process of surface discharge and it can be extended to other state diagnoses of partial discharge phenomena. From the point of view of potential application, this method also provides a new simple method to meet the requirement of long time scale state monitoring in industrial application.

Single-Shot Through-Focus Image Acquisition and Phase Retrieval From Chromatic Aberration and Multi-Angle Illumination

Phase recovery from a stack of through-focus intensity images is an effective non-interference quantitative phase imaging strategy. Nevertheless, the implementations of these methods are expensive and time-consuming because the distance between each through-focus plane has to be guaranteed by precision mechanical moving devices, and the multiple images must be acquired sequentially. In this article, we propose a single-shot through-focus intensity image stack acquisition strategy without any precision movement. Isolated LED units are used to illuminate the sample in different colors from different angles. Due to the chromatic aberration characteristics of the objective, the color-channel defocus images on the theoretical imaging plane are mutually laterally shifted. By calculating the shift amount of each sub-image area in each color channel, the distances between each through-focus image can be obtained, which is a critical parameter in transport of intensity equation (TIE) and alternating projection (AP). Lastly, AP is used to recover the phase distribution and realize the 3D localization of different defocus distances of the sample under test as an example. Both simulation and experiments are conducted to verify the feasibility of the proposed method.

Recent development of coloring alloys

In this study, we systematically reviewed the strategy of the tailoring intrinsic color characteristics of chromatic and achromatic metallic materials. Its scientific contribution involves defining and expanding the range of coloration of metallic materials, including single-phase solid-solution alloys and multiphase alloys that includes specific phases with chromatic colors. In chromatic single-phase alloys, the modulation of optical properties depends on the transition energy of the solid solution phase. The additional alloying elements significantly influence the optical properties, i.e., the reflectivity in the visible spectrum, by varying the transition energy of the solid solution phase. Another coloring alloy design strategy varies and realizes the intrinsic color based on the multiphase system. In particular, the microstructural design based on the multiphase forming alloy system, including the chromatic coloring phase, effectively improves the chromaticity of the alloys by blending effect from the constitutive phases. A methodological framework is subsequently suggested to realize chromatic characteristics based on the juxtaposition method. The novel alloy design method using the juxtaposition method can be considered an important strategy for developing novel coloring alloys with high chromatic color durability from achromatic metallic materials.

Accelerating Aging of White and Red Wines by the Application of Hydrostatic High Pressure and Maceration with Holm Oak (Quercus ilex) Chips. Influence on Physicochemical and Sensory Characteristics.

Background: The use of holm oak (Quercus ilex) chips as a potential alternative wood and the application of hydrostatic high pressure (HHP) as an alternative technique to accelerate the release to the wine of wood-related compounds within a short processing time were evaluated. Methods: Five treatments were investigated: (i) bottling without any treatment (B); (ii) and (iii) bottling after maceration (5 g/L) of holm oak chips with HHP treatments (400 MPa, 5 and 30 min) (HHP5, HHP30); (iv) bottling after maceration during 45 days with chips (M), and; (v) maceration in tanks without chips (T). The effects of treatments on general parameters, polyphenols, color, and sensorial characteristics of red and white wines were investigated over 180 days. Results: HHP5, HHP30, and M increased the polyphenols content, thus modified the chromatic characteristics regarding B and M treatments of white wines, also the tasters differentiated HHP5, HHP30, and M from B and T. However, these effects were not observed in red wines. Thus, the effect of the wood depends on the type of wine in which it is used. Conclusions: This research contributes to better knowledge about these chips as a new alternative wood species and the use of HHP as a useful technology to accelerate the aging of wines.