The ability of certain dyestuffs to change colour in a predictable and reversible way with the change in temperature is a property that can be well utilized in smart textiles. Accurate and repeatable ...determination of the chromatic response of the dye stuff and as an extension of the textile material dyed using these dyes in a significant step towards developing such smart textiles. In this regard the current research project proposes a method for investigating the thermochromic properties of textiles using a custom made testing setup, that includes a digitally controlled heating and cooling equipment as well as a set up to obtain the chromatic response of the textiles every 0.5 °C. Moreover, the proposed set up allows for the investigation of heating/ cooling cycling of the specimens, to confirm the repeatability of the chromatic response of the specimens.
The photodegradation of white spruce by artificial ageing was studied by several techniques: colourimetry, FTIR-ATR and FT-Raman spectroscopy. Samples were exposed at a xenon lamp for 2000h. Two ...distinct colour changes were found by colourimetric analysis, yellowing and silvering. These colour modifications indicate the formation of chromophoric structures which supports previous FTIR-ATR experiments. The degradation of lignin to generate the first chromophoric group for yellowing and then the appearance of surface layer cellulose. New carbonyl compounds conjugated with double bond at 1615cm−1 are probably the second chromophoric group. The crystallinity index was also calculated and showed an increase of cellulose crystallinity by prior degradation of amorphous cellulose. The FT-Raman analysis confirms the wood sensitivity to photodegradation but the most remarkable results is the increase of fluorescence as a function of time. In softwood lignin, the compound able to produce fluorescence is a free rotating 5–5′ linkage of one biphenyl structure. At native state these linkages are not free rotating, this phenomenon means the release of 5–5′ linkage of lignin structure by cleavage of both α carbon linkages (Norrish type I reaction). These data confirm also the photosensitivity of α and β carbon in lignin and the resistance of 5–5′ linkages.
•A colour and FTIR-ATR spectroscopy were used for wood photodegradation.•A new way for monitoring wood photodegradation is proposed.•First used of Raman spectroscopy for wood photodegradation characterization.•A local lignin sensitivity is found and a mechanism of degradation is proposed.
•Protein content of industrial guar meal fractions are in the range of 32–52%.•Trypsin inhibitor content was found to be negligible in industrial guar meal.•Saponin, tannin, and phytate were present ...in all the tested fractions.•Heat treatments were effective in partial removal of antinutritional factors.
Proximate composition analysis and antinutritional factor composition of different fractions of industrial guar meal: raw churi (IRC), heated churi (IHC), final churi (IFC) and guar korma (IGK) were studied and compared. Protein content was found to be very high in IGK (52.7%) when compared to the churi fractions (32–33%) and the trypsin inhibitor activities were found to be negligible in all the fractions (0.58–1.8mg/g). Single fraction (IGK) was selected for further studies, based on the protein content. The antinutritional factors of selected fractions were significantly reduced by different heat treatments. Heat treatments significantly increased the water absorbing capacity of IGK, but reduced the nitrogen solubility, emulsifying and foaming capacity. Highest L∗ value was observed for boiled IGK, highest a∗ and b∗ values for roasted IGK, during colour measurement. FTIR spectral analysis revealed the presence several aromatic groups in IGK and slight modifications in the molecular structure during heat treatments.
•Natural dye extracted from sawdust of Pterocarpus indicus Willd. using ultrasound.•Dyeing and mordanting parameters were optimized.•Pretreatment of cotton and silk improved colour depth, fastness ...and UV protection.•Timber industry waste can be upcycled as a resource for natural dye.
Exploitation of synthetic dyes in a variety of manufacturing sectors including textiles poses serious problems to the environment. Natural dyes are becoming vital alternatives to toxic synthetic dyes, however, with limitations such as availability and process standardization. Herein, we explore the dyeing potential of a sawdust, Pterocarpus indicus Willd., which is widely available as a waste from timber industry in South Asia and other parts of the world. Ultrasound assisted extraction method was carried out to extract natural dye from the sawdust. The extract was used to dye cotton and silk fabrics using various metallic and natural mordants such as alum, stannous chloride, copper sulphate, gallnut, pomegranate rind and gooseberry and the process was optimized. The effect of different pretreatments such as chitosan and myrobalan on dyeing fabrics was also studied. Colour properties of the naturally dyed fabrics such as colour strength, colour co-ordinates and various fastness were assessed. The natural mordants such as gallnut, pomegranate rind and gooseberry provided comparable fastness property to metallic mordants, thereby suggesting the use of the extracted dye with natural mordants for exclusive eco-friendly dyeing. We also demonstrate that chitosan and myrobalan pretreatments significantly enhance the colour strength, colour fastness and UV protection properties of naturally colored cotton and silk fabrics. Overall, the results suggest copper sulphate mordanting with chitosan pretreatment and stannous chloride mordanting with myrobalan pretreatment as the best combination for cotton and silk fabrics, respectively considering the color fastness and UV protection properties. The results provide ample scope for the upcycling of timber industry waste into a natural dye for eco-friendly coloration of fabrics.
Digital photography and spectrometry are widely used for colour measurement, but both methods have a number of advantages and disadvantages. Comparative studies can help determine the most ...appropriate method for quantifying animal colour perception, but few have attempted to compare them based on colour model conversion. Here we compare colour measurements from digital photography and spectrometry in a controlled standard experimental environment using the three-dimensional colour space model CIE
L
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a
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b
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which is designed to approximate colour perception in humans and assess the repeatability and agreement of the two methods. For digital photography, we first extracted
RGB
values from each colour patch and transferred these to
L
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values using colour model conversion. For spectrometry, we measured the spectral reflectance (
SR
) value and subsequently transferred
SR
values to
L
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a
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b
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values. Using a consensus of correlation analysis, intraclass correlation coefficients, concordance correlation coefficients, and Bland-Altman analysis, we found that although spectrometry showed a slightly higher repeatability than photography, both methods were highly repeatable and showed a strong agreement. Furthermore, we used Bland-Altman analysis to derive the limits of agreement, which can be used as criteria for identifying when photography and spectrometry could be as a suitable alternative for measuring colour perception in humans and other trichromatic species. We suggest that our workflow offers a practical and logical approach that could improve how we currently study colour perception in trichromats.
Significance statement
Measuring colour efficiently and accurately is necessary for investigating the evolutionary biology of colour perception in animals. Digital photography and spectrometry are two methods widely used for colour measurement, but there are benefits and limitations to using either method. Comparative studies based on colour model conversion are therefore critical for helping researchers determine which method is most appropriate. Here we test the repeatability and agreement of the two measuring methods using standard colour patches, as a comparative case study of broader interest in measuring colour perception in humans and similar primates. Our results demonstrate that both methods are highly repeatable, and the two methods may be used interchangeably to measure colour perception in humans under experimental conditions.
Summary
Quantitative measurements of colour, pattern and morphology are vital to a growing range of disciplines. Digital cameras are readily available and already widely used for making these ...measurements, having numerous advantages over other techniques, such as spectrometry. However, off‐the‐shelf consumer cameras are designed to produce images for human viewing, meaning that their uncalibrated photographs cannot be used for making reliable, quantitative measurements. Many studies still fail to appreciate this, and of those scientists who are aware of such issues, many are hindered by a lack of usable tools for making objective measurements from photographs.
We have developed an image processing toolbox that generates images that are linear with respect to radiance from the RAW files of numerous camera brands and can combine image channels from multispectral cameras, including additional ultraviolet photographs. Images are then normalised using one or more grey standards to control for lighting conditions. This enables objective measures of reflectance and colour using a wide range of consumer cameras. Furthermore, if the camera's spectral sensitivities are known, the software can convert images to correspond to the visual system (cone‐catch values) of a wide range of animals, enabling human and non‐human visual systems to be modelled. The toolbox also provides image analysis tools that can extract luminance (lightness), colour and pattern information. Furthermore, all processing is performed on 32‐bit floating point images rather than commonly used 8‐bit images. This increases precision and reduces the likelihood of data loss through rounding error or saturation of pixels, while also facilitating the measurement of objects with shiny or fluorescent properties.
All cameras tested using this software were found to demonstrate a linear response within each image and across a range of exposure times. Cone‐catch mapping functions were highly robust, converting images to several animal visual systems and yielding data that agreed closely with spectrometer‐based estimates.
Our imaging toolbox is freely available as an addition to the open source ImageJ software. We believe that it will considerably enhance the appropriate use of digital cameras across multiple areas of biology, in particular researchers aiming to quantify animal and plant visual signals.
Identifying colour from a distance is challenging due to the external noise associated with the measurement process. The present study focuses on developing a colour measuring system and a novel ...Multi-target Regression (MTR) model for accurate colour measurement from distance. Herein, a novel MTR method, referred as Multi-Objective Stacked Regression (MOSR) is proposed. The core idea behind MOSR is based on stacking as an ensemble approach with multi-objective evolutionary learning using NSGA-II. A multi-objective optimization approach is used for selecting base learners that maximises prediction accuracy while minimising ensemble complexity, which is further compared with six state-of-the-art methods over the colour dataset. Classification and regression tree (CART), Random Forest (RF) and Support Vector Machine (SVM) were used as regressor algorithms. MOSR outperformed all compared methods with the highest coefficient of determination values for all three targets of the colour dataset. Rigorous comparison with state-of-the-art methods over 18 benchmarked datasets showed MOSR outperformed in 15 datasets when CART was used as a regressor algorithm and 11 datasets when RF and SVM were used as regressor algorithms. The MOSR method was statistically superior to compared methods and can be effectively used to measure accurate colour values in the distance-based colour measuring device.
To be effective, animal colour signals must attract attention—and therefore need to be conspicuous. To understand the signal function, it is useful to evaluate their conspicuousness to relevant ...viewers under various environmental conditions, including when visual scenes are cluttered by objects of varying colour. A widely used metric of colour difference (Δ
S
) is based on the receptor noise limited (RNL) model, which was originally proposed to determine when two similar colours appear different from one another, termed the discrimination threshold (or just noticeable difference). Estimates of the perceptual distances between colours that exceed this threshold—termed ‘suprathreshold’ colour differences—often assume that a colour's conspicuousness scales linearly with colour distance, and that this scale is independent of the direction in colour space. Currently, there is little behavioural evidence to support these assumptions. This study evaluated the relationship between Δ
S
and conspicuousness in suprathreshold colours using an Ishihara-style test with a coral reef fish,
Rhinecanthus aculeatus
. As our measure of conspicuousness, we tested whether fish, when presented with two colourful targets, preferred to peck at the one with a greater Δ
S
from the average distractor colour. We found the relationship between Δ
S
and conspicuousness followed a sigmoidal function, with high Δ
S
colours perceived as equally conspicuous. We found that the relationship between Δ
S
and conspicuousness varied across colour space (i.e. for different hues). The sigmoidal detectability curve was little affected by colour variation in the background or when colour distance was calculated using a model that does not incorporate receptor noise. These results suggest that the RNL model may provide accurate estimates for perceptual distance for small suprathreshold distance colours, even in complex viewing environments, but must be used with caution with perceptual distances exceeding 10 Δ
S
.
Using digital photography to study animal coloration STEVENS, MARTIN; PÁRRAGA, C. ALEJANDRO; CUTHILL, INNES C. ...
Biological journal of the Linnean Society,
February 2007, 20070201, Letnik:
90, Številka:
2
Journal Article
Objectives
In systematically healthy patients with an implant‐supported fixed restoration (P), what is the influence of thin (E) as compared to thick (C) peri‐implant soft tissues on aesthetic ...outcomes (O)?
Methods
Following an a priori protocol, a literature search of six databases was conducted up to August 2020 to identify prospective/retrospective clinical studies on healthy patients with an implant‐supported fixed reconstruction. Measurement of the buccal soft tissue thickness and an aesthetic outcome was a prerequisite, and sites presenting with a buccal soft tissue thickness of <2 mm or shimmering of a periodontal probe were categorized as a thin phenotype. After study selection, data extraction, and risk of bias assessment, random‐effects meta‐analysis of Mean Differences (MD) or Odds Ratios (OR) with their corresponding 95% Confidence Intervals (CI) were conducted, followed by sensitivity analyses and assessment of the quality of evidence.
Results
Thirty‐four unique studies reporting on 1508 patients with 1606 sites were included (9 randomized controlled trials, one controlled trial, 10 prospective cohort studies, 8 cross‐sectional studies, and 6 retrospective cohort studies). The mean difference of the pink aesthetic score (PES) after the follow‐up was not significantly different between thin (<2.0 mm) or thick soft tissues (≥2.0 mm) or phenotypes (12 studies; MD = 0.15; 95% CI = −0.24, 0.53; p = .46). PES changes during the follow‐up, however, were significantly in favour of thick soft tissues (≥2.0 mm) or phenotypes (p = .05). An increased mean mucosal thickness was associated with an increased papilla index (5 studies; MD = 0.5; 95% CI = 0.1, 0.3; p = .002) and an increase in papilla presence (5 studies; OR = 1.6; 95% CI = 1.0, 2.3; p = .03). Thin soft tissues were associated with more recession, −0.62 mm (4 studies; 95% CI = −1.06, −0.18; p = .006). Patient‐reported outcome measures (patient satisfaction) were in favour of thick soft tissues −2.33 (6 studies; 95% CI = −4.70, 0.04; p = .05). However, the quality of evidence was very low in all instances due to the inclusion of non‐randomized studies, high risk of bias and residual confounding.
Conclusion
Within the limitations of the present study (weak study designs and various soft tissue measurements or time‐points), it can be concluded that increased soft tissue thickness at implant sites was associated with more favourable aesthetic outcomes.
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