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Colour Differences (colour + difference)

Distribution by Scientific Domains

Chemistry	42%
Medical Sciences	26%
Life Sciences	26%

Selected Abstracts

Tristimulus algorithm of colour matching for precoloured fibre blends based on the Stearns,Noechel model

COLORATION TECHNOLOGY, Issue 2 2006
L I Rong
Prediction of the formula for matching a given colour standard by blending predyed fibres is of considerable importance to the textile industry. This kind of formulation lacks a computer-aided tool to assist colourists to find a good recipe to reproduce a target colour. In this study a tristimulus colour-matching algorithm based on the Stearns,Noechel model is proposed. This algorithm was run to predict recipes for 54 viscose blends. Colour differences between the original blend samples and the blend samples prepared according to the matched recipes were measured and expressed in CIELab 1976 units (D65 illuminant and 10° standard observer). Used in the classical way, in which the parameter M (the empirical constant in the Stearns,Noechel model) equals 0.09, the maximum colour difference is 2.16 CIELab units. The average computed colour difference is 0.69 CIELab units. It is demonstrated that the algorithm can be used in colour matching of fibre blends. A new method to acquire the set of M values is proposed in this study. [source]

The optimization of the extrusion process when using maize flour with a modified amino acid profile for making tortillas

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2006
Jorge Milán-Carrillo
Summary Maize with a modified amino acid profile, i.e. greater amounts of lysine and tryptophan than normal, is known as ,quality protein maize' (QPM). The objective of this work was to find the best combination of extrusion process variables to produce QPM flour for making tortillas. QPM grits were mixed with lime and water and had a moisture content of 28%. The single screw extruder operation conditions were selected from factorial combination of three process variables: extrusion temperature (ET, 70,100 °C), lime concentration (LC, 0.1,0.3% of the maize weight) and screw velocity (SV, 80,250 rpm). Response surface methodology was used as an optimization technique. In vitro protein digestibility (PD); total colour difference (,E) of the flours, and tortilla puffing (TP) were chosen as response variables. A graphical method was used to obtain maximum PD, TP and minimum ,E. The optimum combination of process variables was: ET = 85 °C/LC = 0.21%(w/w)/SV = 240 rpm. Tortillas from QPM flour had similar chemical composition, physicochemical and sensory properties to tortillas from commercial nixtamalized maize flour; however, the former had the highest (P , 0.05) available lysine content and were therefore better nutritionally. [source]

The effects of polishing and bleaching on the colour of discoloured teeth in vivo

JOURNAL OF ORAL REHABILITATION, Issue 11 2001
T. Nakamura
Bleaching is an effective method for restoring the colour of discoloured vital teeth. Power bleaching, in particular, in which a bleaching solution containing 35% hydrogen peroxide is activated by a strong light source using a plasma arc, makes it possible to bleach teeth effectively in a short time. The purpose of this study was to determine how polishing or power bleaching the tooth surface affects tooth colour. The subjects selected were patients who had slightly discoloured teeth. The colour of precisely identified sites on six anterior teeth was measured before treatment, after polishing and after bleaching, to ascertain changes in colour. The measurements revealed that tooth colour changes slightly after polishing, but it shows a much greater change after bleaching, and that the post-bleaching change in tooth colour was caused both by elevation of lightness and reduction of yellowness. They also revealed that the colour difference between pre-treatment and post-bleaching does not depend on the type of tooth. These results suggested that power bleaching is an effective technique for improving slightly discoloured vital teeth, regardless of the type of tooth. [source]

A response surface methodology approach to optimise pretreatments to prevent enzymatic browning in potato (Solanum tuberosum L) cubes

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2002
C Reyes-Moreno
Abstract The objective of this work was to find the best combinations of ascorbic acid concentration/soaking time (Pretreatment 1), 4-hexylresorcinol concentration/soaking time (Pretreatment 2) and ascorbic acid concentration,4-hexylresorcinol concentration/soaking time (Pretreatment 3) to prevent the development of enzymatic browning in raw potato cubes (10,mm,×,10,mm,×,10,mm). Potato variety Alpha was used as study model because of its low susceptibility to enzymatic browning. Response surface methodology was applied in all pretreatments on two response variables (Hunter L value and total colour difference) to find the best conditions for carrying out the pretreatments. The various pretreatments had variation levels for ascorbic acid (AA) concentration (1 and 3) and 4-hexylresorcinol (4HR) concentration (2 and 3) of 1,4 and 0.04,0.20,g,l,1 respectively; in all pretreatments the variation level for soaking time was 3,6,h. A central composite experimental design with two factors at five levels was used. Predictive models for Hunter L value and total colour difference were developed as a function of process or independent variables. The optimisation technique was applied to obtain maximum Hunter L values and minimum values of total colour difference. Surface superposition of these variables allowed identification of the best combinations of process variables for each pretreatment as (1) 2.9,g,l,1 AA/4.8,h, (2) 0.04,g,l,1 4HR/2.6,h and (3) 2.42,g,l,1 AA,0.15,g,l,1 4HR/5.41,h. © 2001 Society of Chemical Industry [source]

The effect of texture on the pass/fail colour tolerances of injection-molded plastics

COLOR RESEARCH & APPLICATION, Issue 1 2007
Ingrid Ariño
Abstract The effect of surface texture on the pass/fail colour tolerance region was estimated using acrylonitrile,butadiene,styrene injection-molded plaques in three different colours and with different surface textures. Variations in the measured colour coordinates due to differences in texture for three selected colours were observed using the specular component excluded mode (SCE) of the spectrophotometer. Such variations could not, however, be clearly distinguished in the specular component included mode. The colour tolerance regions were assessed through a combination of colour measurement and a psychometric study involving 35 observers. The limits of acceptance of colour differences varied substantially with the surface texture. In some cases, the observers accepted a larger colour difference for the textured than for the smooth surface, whereas in other cases, the reverse situation was noted. Thus, no general conclusion regarding the influence of texture on the tolerance region can be drawn, since the acceptable differences were colour- and/or surface texture-dependent. In the case of textured surfaces, measurements made in the SCE mode of the spectrophotometer appear to be more meaningful for assessing perceived colour differences and tolerance regions. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 47,54, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20284 [source]

Tristimulus algorithm of colour matching for precoloured fibre blends based on the Stearns,Noechel model

Correlated morphological and colour differences among females of the damselfly Ischnura elegans

ECOLOGICAL ENTOMOLOGY, Issue 3 2009
JESSICA K. ABBOTT
Abstract 1.,The female-limited colour polymorphic damselfly Ischnura elegans has proven to be an interesting study organism both as an example of female sexual polymorphism, and in the context of the evolution of colour polymorphism, as a model of speciation processes. 2.,Previous research suggests the existence of correlations between colour morph and other phenotypic traits, and the different female morphs in I. elegans may be pursuing alternative phenotypically integrated strategies. However, previous research on morphological differences in southern Swedish individuals of this species was only carried out on laboratory-raised offspring from a single population, leaving open the question of how widespread such differences are. 3.,The present study therefore analysed multi-generational data from 12 populations, investigating morphological differences between the female morphs in the field, differences in the pattern of phenotypic integration between morphs, and quantified selection on morphological traits. 4.,It was found that consistent morphological differences indeed existed between the morphs across populations, confirming that the previously observed differences were not simply a laboratory artefact. It was also found, somewhat surprisingly, that despite the existence of sexual dimorphism in body size and shape, patterns of phenotypic integration differed most between the morphs and not between the sexes. Finally, linear selection gradients showed that female morphology affected fecundity differently between the morphs. 5.,We discuss the relevance of these results to the male mimicry hypothesis and to the existence of potential ecological differences between the morphs. [source]

Iridescent hindwing patches in the Pipevine Swallowtail: differences in dorsal and ventral surfaces relate to signal function and context

FUNCTIONAL ECOLOGY, Issue 4 2010
Ronald L. Rutowski
Summary 1.,Iridescent colour signals are directional but, like diffusely reflected colours, vary within and among species in ways that may be adaptations to specific types of receivers in specific light environments. 2.,The hindwings of pipevine swallowtail butterflies exhibit brilliant blue and iridescent colour patches on the ventral surface in both sexes and on the dorsal wing surface in males. Evidence suggests that the ventral iridescent blue is a component of the warning coloration of this distasteful species, while the dorsal blue iridescent wing area is a sexual signal. Given differences in the function and ecological context of signal production, we analysed reflectance spectra from the iridescent blue areas of both field-caught and laboratory-reared animals to test several predictions about the iridescent colour patches on these wing surfaces. 3.,The ventral blue patches in the warning coloration of males and females should be most visible early and late in the day, due to wing orientation relative to sun angle. We therefore predicted that these iridescent colour patches would be brighter and of longer wavelengths than the male dorsal blue patch displayed during midday courtships. The prediction about reflectance intensity was supported but the prediction about hue was not. 4.,We predicted that the sexually selected dorsal hindwing iridescence of males would be more variable among individuals and condition dependent than the naturally selected ventral iridescent colour patches. To assess variation and condition dependence, laboratory-reared and field-captured individuals were compared. The prediction about variation was not supported, but only the dorsal wing surfaces showed evidence of being condition dependent. 5.,We investigated whether development of dorsal and ventral blue iridescence was coupled by determining correlations in colour properties between the wing surfaces. Our finding of positive correlations indicated a potential developmental constraint in the evolution of colour differences between the two wing surfaces. 6.,Results of this study suggest that some properties of iridescent coloration on the hindwing of the pipevine swallowtail (especially intensity) may have been fine-tuned by evolution in response to prevailing ambient light conditions and viewing perspectives that differ among types of signal receivers. [source]

Interspecific variation in plumage colour among birds: species recognition or light environment?

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2002
Melinda K. McNaught
Abstract The traditional explanation for interspecific plumage colour variation in birds is that colour differences between species are adaptations to minimize the risk of hybridization. Under this explanation, colour differences between closely related species of birds represent reproductive character displacement. An alternative explanation is that interspecific variation in plumage colour is an adaptive response to variation in light environments across habitats. Under this explanation, differences in colour between closely related species are a product of selection on signal efficiency. We use a comparative approach to examine these two hypotheses, testing the effects of sympatry and habitat use, respectively, on divergence in male plumage colour. Contrary to the prediction of the Species Isolation Hypothesis, we find no evidence that sympatric pairs of species are consistently more divergent in coloration than are allopatric pairs of species. However, in agreement with the Light Environment Hypothesis, we find significant associations between plumage coloration and habitat use. All of these results remain qualitatively unchanged irrespective of the statistical methodology used to compare reflectance spectra, the body regions used in the analyses, or the exclusion of areas of plumage not used in sexual displays. Our results suggest that, in general, interspecific variation in plumage colour among birds is more strongly influenced by the signalling environment than by the risk of hybridization. [source]

In vivo spectroradiometric evaluation of colour matching errors among five shade guides

JOURNAL OF ORAL REHABILITATION, Issue 1 2009
Q. LI
Summary, The purpose of this study was to evaluate the colour errors of visual shade selection by five different shade guides. The maxillary left central incisors of sixty participants were visually evaluated by two groups of prosthodontists, with different clinical experience. The shade selection results were recorded and the most selected tab was determined as the resultant shade for each tooth. If totally different opinions were obtained, consensus was needed to determine the resultant shade among the observers. The colour distributions (L*, a* and b*) of each tooth and shade tab were measured using a spectroradiometer. The coverage errors (CEs) of each shade guide and colour differences (,E values) between a tooth and the selected shade tabs were calculated. Two-way anova and Tukey's post hoc analysis were used to evaluate the differences of CE and ,E values among shade guides and clinical experience (, = 0·05). Coverage errors and ,E values in all of the five shade guide systems were all beyond the clinical threshold of 3·3 units. The consensus led to a better colour matching than that of the single decision group in Vitapan 3D-Master and Shofu NCC shade guides. A significant difference (P < 0·001) was found among ,E values of the shade guide system and clinical experience. In conclusion, all five of the shade guide systems used did not achieve clinically compatible shade matching. However, the Vitapan 3D Master shade guide system resulted in the lowest CEs and ,E values. Consensus could be helpful in enhancing the aesthetic results using Vitapan 3D Master and Shofu NCC shade guides. [source]

Translucency of glass-fibre-reinforced composite materials

JOURNAL OF ORAL REHABILITATION, Issue 8 2004
T. Nakamura
summary, The purpose of this study was to examine the translucency of glass-fibre-reinforced composite framework materials. Vectris and FibreKor, as well as an experimental material, were the glass-fibre-reinforced framework materials used. Targis, Sculpture and Estenia were the types of particulate filler composites veneered onto frameworks. Specimens were fabricated from each material, 0·5 and 1·0 mm thick. In addition, laminate specimens, 1·5 mm thick, were fabricated. The translucency of each specimen was evaluated by determining its contrast ratio. The laminate specimens were examined for colour differences. The experimental framework material was more translucent than the enamel composite when it was not coloured, and was nearly as translucent as the dentine composite when coloured. The commercial tooth-coloured framework materials were nearly as translucent as the dentine composite. It was found that it was possible to reproduce the same colour as the veneering dentine composite, when the framework thickness was 0·5 mm, except in the case of FibreKor. Within the limitations of this study, tooth-coloured, glass-fibre-reinforced framework materials are nearly as translucent as the veneering dentine composite, but these materials affect the colour of the prosthesis if the thickness of the framework material is increased beyond a certain point. [source]

Changes in surface roughness and colour stability of soft denture lining materials caused by denture cleansers

JOURNAL OF ORAL REHABILITATION, Issue 2 2003
C. Jin
summary, Soft denture lining materials were immersed into solutions of denture cleansers for 8 h at room temperature, and immersed into distilled water for the remainder of the 24-h period at 37 °C. Surface roughness of the soft denture lining materials was measured by contact type surface roughness instrument. For the colour stability test, soft denture lining materials were immersed in the denture cleansers as described above for 180 days. Finally, the colour changes of each material were quantitatively measured by a photometrical instrument to obtain the colour differences between newly processed specimen and immersed specimens (P < 0·01). An autopolymerizing silicone material, Evatouch, exhibited severe changes in surface roughness by all denture cleanser, and the generic material GC Denture Relining showed the minimal changes. Severe colour changes were also observed with some liner and cleanser combinations (P < 0·01). Except for Evatouth, the four silicone soft liners were more stable in surface roughness and in colour change than the two acrylic soft liners. One autopolymerizing silicone (GC denture relining) and one heat curing silicone (Molloplast B) demonstrated the best stability. [source]

Erythema measurements may allow early diagnosis of diabetes mellitus in adult psoriatics

JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 3 2003
O Avci
ABSTRACT Background ,We have observed that the erythema in subjects with psoriasis vulgaris associated with non-insulin-dependent diabetes mellitus (NIDDM) presents a mostly deep-red to purple hue instead of the typical pink to red tones. We carried out a descriptive clinical study, including 141 patients with psoriasis vulgaris to quantify these colour differences. Methods, Mean erythema index values were established for the psoriatic plaques of adult subjects using an optoelectronic method. Non-diabetic psoriatics underwent an oral glucose tolerance test (OGTT), and based on the results of the oral OGTTs, the subjects were divided into three groups: 18 psoriatics with NIDDM, 16 psoriatics with impaired glucose tolerance (IGT) and 107 psoriatics with normal glucose tolerance. The mean erythema index value was calculated for each group and the findings were compared. Results, The differences in the erythema were found to be highly significant between the group of subjects with psoriasis having normal glucose tolerance and both those with IGT and those with NIDDM (P < 0.01 and P < 0.01). The differences in the erythema were also highly significant between the psoriatic group with normal glucose tolerance and the group of 34 psoriatics with IGT and NIDDM all together (P < 0.01). Conclusions, Individuation of the various hues of erythema in psoriatics by careful dermatological examination or routine measurements of lesional erythema may alert the physician to possible IGT in the presenting subject, and this may affect disease severity. [source]

A Subaru/Suprime-Cam wide-field survey of globular cluster populations around M87 , I. Observation, data analysis and luminosity function

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006
Naoyuki Tamura
ABSTRACT In this paper and a companion paper, we report on a wide-field imaging survey of the globular cluster (GC) populations around M87 carried out with Suprime-Cam on the 8.2-m Subaru telescope. Here, we describe the observations, data reduction and data analysis, and present luminosity functions of GC populations around M87 and NGC 4552, another luminous Virgo elliptical in our survey field. The imaging data were taken in the B, V and I bands with a sky coverage of extending from the M87 centre out to ,0.5 Mpc. GC candidates were selected by applying a colour criterion on the B,V and V,I diagram to unresolved objects, which greatly reduces contamination. The data from control fields taken with Subaru/Suprime-Cam were also analysed for subtraction of contamination in the GC sample. These control field data are compatible with those in the M87 field in terms of the filter set (BVI), limiting magnitudes and image quality, which minimize the possibility of introducing any systematic errors into the subtractive correction. We investigate GC luminosity functions (GCLFs) at distances , 10 arcmin (,45 kpc) from the host galaxy centre in detail. By fitting Gaussians to the GCLFs, the V -band turnover magnitude (VTO) is estimated to be 23.62 ± 0.06 and 23.56 ± 0.20 mag for the GC population in M87 and NGC 4552, respectively. The GCLF is found to be a function of GC colour; VTO of the red GC subpopulation (V,I > 1.1) is fainter than that of the blue GC subpopulation (V,I, 1.1) in both M87 and NGC 4552, as expected if the colour differences are primarily due to a metallicity effect, and the mass functions of the two subpopulations are similar. The radial dependence of the GCLF is also investigated for the GC population in M87. The GCLF of each subpopulation at 1 ,R, 5 arcmin is compared to that at 5 ,R, 10 arcmin, but no significant trend with distance is found in the shape of the GCLF. We also estimate GC-specific frequencies (SN) for M87 and NGC 4552. The SN of the M87 GC population is estimated to be 12.5 ± 0.8 within 25 arcmin. The SN value of the NGC 4552 GC population is estimated to be 5.0 ± 0.6 within 10 arcmin. [source]

Plumage colour mutations and melanins in the feathers of the Japanese quail: a first comparison

ANIMAL GENETICS, Issue 6 2009
F. Minvielle
Summary The absorbance of melanin content from dorsal feathers was compared between wild-type Japanese quail and nine other quail plumage colours determined by single mutations in one of seven genes: extended brown (MC1R), yellow (ASIP), silver (MITF), lavender (MLPH), roux (TYRP1), imperfect albinism (SLC45A2) and rusty. As compared with wild-type quail, all mutations but extended brown decreased total melanins. The largest decrease was observed in quail with one of the dilution mutations at TYRP1, MLPH or SLCA45A2. No difference in eumelanins was found between the 10 plumage colours. Despite visible colour differences, homozygous and heterozygous mutants at MITF, or the two imperfect albino (white) and cinnamon (pale yellow) alleles at SLC45A2, could not be differentiated on the basis of melanins. In contrast, the two white phenotypes caused by mutations at MITF and SLC45A2, or the two reddish plumage colours caused by the roux and rusty non-allelic mutations had different total melanin contents. The results showed that rusty was not likely to be a dilution mutation. [source]

Effects of genetics and light environment on colour expression in threespine sticklebacks

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2008
EVA LEWANDOWSKI
The genetic basis of traits that are under sexual selection and that are involved in recognizing conspecific mates is poorly known, even in systems in which the phenotypic basis of these traits has been well studied. In the present study, we investigate genetic and environmental influences on nuptial colour, which plays important roles in sexual selection and sexual isolation in species pairs of limnetic and benthic threespine sticklebacks (Gasterosteus aculeatus species complex). Previous work demonstrated that colour differences among species correlate to differences in the ambient light prevalent in their mating habitat. Red fish are found in clear water and black fish in red-shifted habitats. We used a paternal half-sib split-clutch design to investigate the genetic and environmental basis of nuptial colour. We found genetic differences between a red and a black stickleback population in the expression of both red and black nuptial colour. In addition, the light environment influenced colour expression, and genotype by environment interactions were also present. We found evidence for both phenotypic and genetic correlations between our colour traits; some of these correlations are in opposite directions for our red and black populations. These results suggest that both genetic change and phenotypic plasticity underlie the correlation of male colour with light environment. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 663,673. [source]

The effect of texture on the pass/fail colour tolerances of injection-molded plastics

The surface polymerising of fluoromonomer and the shade-darkening effect on dyed polyester microfibre fabric

COLORATION TECHNOLOGY, Issue 5 2007
Kongliang Xie
The surface polymerising of fluoromonomer on dyed polyester microfibre fabric is investigated. The shade-darkening effect of perfluoropolyester acrylate polymer is discussed by colour yield, reflectance spectrum and the colour differences. The surface polymerising of fluoromonomer on dyed polyester microfibre fabric had an excellent shade-darkening effect. After surface polymerising, the dyed fabrics had no significant effect on washing and wet rubbing fastness. [source]