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At least 19 recordsLinked to original sources
PubMed1999

Color stability and colorant effect on maxillofacial elastomers. Part III: weathering effect on color.

STATEMENT OF PROBLEM: Maxillofacial prostheses are serviceable for approximately 6 months, after which they need to be refabricated because of the deterioration of color and physical properties. PURPOSE: This third article in a 3-part series evaluated the color stability of commonly used colorant-elastomer combinations as a result of exposure to weathering. METHODS AND MATERIAL: Fifteen specimens were fabricated for each of the 3 elastomers (Silastic medical adhesive type A, Silastic 4-4210, and Silicone A-2186) and 6 colorants (dry earth pigments, rayon fiber flocking, artist's oil paints, kaolin, liquid cosmetics, and no colorant) for a total of 270 specimens (18 groups of 15 specimens). The 15 specimens of each elastomer-colorant combination were separated into 3 test condition groups (control, time passage, and natural weathering) of 5 specimens per test condition group. Control specimens were evaluated within 1 month of fabrication. The time passage group was sealed in glass containers and kept in the dark for 6 months before testing. The natural weathering groups were placed on the roof of the dental school for 6 months and exposed to sunlight and weathering. Color and optical density data for each elastomer-colorant combination were subjected to a 1-way analysis of variance to examine effects among test conditions (control, time passage, and weathering). When significant differences were observed, the Student-Newman-Keuls multiple range test was performed to identify differences in elastomer-colorant combinations among each test condition at a significance level of .05. RESULTS: Changes in color, as a result of weathering, were noted in many of the colorant-elastomer combinations. Also, color change occurred not only to the colored, but also to uncolored materials over time without exposure to weathering. CONCLUSION: Clinically, the addition of colorants could have a stabilizing effect on the elastomer color when it is exposed to weathering.

Analysis of Variance↗
PubMed1975

Measurement of surface color and color difference of tablet colorants by tristimulus colorimetry.

The surface color of a series of color dispersions containing from one to three FD&C or D&C dyes suspended in a sucrose syrup was examined using tristimulus colorimetry. CIE (x, y) and Hunter (a, b) chromaticity data, determined directly from an integrating sphere colorimeter or from reflectance spectra and suitable calculations, were used to order materials by color on expanded chromaticity diagrams. Color difference was evaluated quantitatively from Hunter (a, b) data using the Judd color difference formula. Quality control specifications were established either by defining areas of acceptable color by applying limits to the chromaticity coordinates of color standards or by requiring the Judd color difference to be less than a specific number of National Bureau of Standards standard units. This method eliminates the subjective character of color evaluation and permits the quantitation of visual color difference. These differences can be used, in conjunction with defined color standards, to develop color specifications for tablet colorants, finished tablets, and liquid and cream pharmaceutical preparations.

Color↗
PubMed1975

The color of gingiva studied by visual color matching. Part II. Kind, location, and personal difference in color of gingiva.

A replica of natural gingival color can be fabricated in a prosthesis. A precise record of gingival color helps to follow-up oral and systemic diseases. A healthy gingival color according to the "Periodontal Workshop Committee I" is 'pink' but no indication is given for color variations by age or position. For more precise definition, therefore, gingival color was examined in the maxillary and mandibular anterior regions by visual color matching using standard color chips after Munsell's system. Gingival color was measured in 60 subjects, in 18 locations around the anterior teeth. 1. The gingival color varies in Hue from 10 RP to 2.5 YR, being mainly between 2.5 R and 5 R; in Value from 4 to 8, maximum between 6 and 7.5; and in Chroma from 1.5 to 7, mainly from 4 to 5. 2. No difference in gingival color is recognized between the male and female, or between left and right sides of the jaw. 3. Gingival color varies with the position of papillary, marginal, and attached gingivae, and the parts corresponding to different teeth have different colors. 4. The gingival color of young persons, differs markedly from that of older people. In all the parts, red Hue is more tinged with purple in the old than in the young; Value is higher in the young; and Chroma is higher in the old.

Adolescent↗
PubMed1999

Color discrimination, color naming and color preferences in 80-year olds.

The aim of the present study was to investigate color discrimination, color naming and color preference in a random sample of 80-year-old men and women. Knowledge of color perception in old age can be of value when using color contrast, cues and codes in the environment to promote orientation and function. The color naming test indicated that the colors white, black, yellow, red, blue and green promoted recognition to the highest degree among all subjects. A gender-related difference, in favor of women, occurred in naming five of the mixed colors. Women also used more varied color names than men. Color discrimination was easier in the red and yellow area than in the blue and green area. This result correlates positively with visual function on far sight, and negatively with diagnosis of a cataract. The preference order for seven colors put blue, green and red at the top, and brown at the bottom, hence agreeing with earlier studies, and indicating that the preference order for colors remains relatively stable also in old age. This result should be considered when designing environments for old people.

Aged↗
PubMed1975

The color of gingiva studied by visual color matching. Part I. Experimental studies on the discrimination threshold for color difference and effect of training.

As a preliminary experiment on the gingival color indicated by Munsell system, the makings or the qualities for color sensation of the individual were checked with regard to (1) discrimination threshold for color difference with certain color range of gingiva (paired difference test for color comparison) and (2) promotion of memorial power by training (test for memory color). A total of 20 males and females (20-30 years old) participated in this preliminary study as experimental subjects and the following results were obtained: (1) the average color discrimination threshold for color difference among subject trained for color memory is 0.8 Lab. (Hunter), and is assumed to be greater in the actual colorimetry of gingiva, (2) the similarity of discrimination is more frequent among the subjects trained for color memory than among those who were not trained, and (3) training for color memory is found to be effective in promoting the ability for color discrimination.

Adult↗
PubMed2001

Specific screening for color precursors and colorants in beet and cane sugar liquors in relation to model colorants using spectrofluorometry evaluated by HPLC and multiway data analysis.

A comparison was made of the fluorophores in beet thick juice and cane final evaporator syrup, which are comparable in the production of cane and beet sugar; that is, both represent the final stage of syrup concentration prior to crystallization of sugar. To further elucidate the nature of the color components in cane and beet syrup, a series of model colorants was also prepared, consisting of mildly alkaline-degraded fructose and glucose and two Maillard type colorants, glucose--glycine and glucose--lysine. Fluorescence excitation--emission landscapes resolved into individual fluorescent components with PARAFAC modeling were used as a screening method for colorants, and the method was validated with size exclusion chromatography using a diode array UV--vis detector. Fluorophores from the model colorants were mainly located at visible wavelengths. An overall similarity in chromatograms and absorption spectra of the four model colorant samples indicated that the formation of darker color was the distinguishing characteristic, rather than different reaction products. The fluorophores obtained from the beet and cane syrups consisted of color precursor amino acids in the UV wavelength region. Tryptophan was found in both beet and cane syrups. Tyrosine as a fluorophore was resolved in only beet syrup, reflecting the higher levels of amino acids in beet processing. In the visible wavelength region, cane syrup colorant fluorophores were situated at higher wavelengths than those of beet syrup, indicating formation of darker colorants. A higher level of invert sugar in cane processing compared to beet processing was suggested as a possible explanation for the darker colorants.

Carbohydrates↗
PubMed1999

Color spaces of color-normal and color-abnormal observers reconstructed from response times and dissimilarity ratings.

With multidimensional scaling analysis, color spaces were reconstructed from reaction times (RTs) required to make same-different judgements of pairs of 15 equiluminant colors and from dissimilarity ratings between them. In addition to normal trichromats, observers with red-green color deficiency were tested. Two main purposes were served by this study: (1) to compare spatial representations of colors derived from discriminative RTs with those derived from dissimilarity measures and (2) to examine whether the task may selectively affect the dimension reflecting, in color-abnormal spaces, the deficient red-green mechanism. Contradicting our hypothesis of lower dimensionality of RT spaces, as compared with rating spaces, no consistent differences in solution dimensionality were found. However, configurations derived from the two measures diverged. The rating procedure yielded the most logical results for recovering color space. The RT configuration revealed contraction in the tritanopic direction, indicating longer color processing when the short-wavelength mechanism is involved, and in addition, for color-abnormal observers, clustering in the protanopic and deuteranopic directions, indicating even longer processing by the deficient red-green mechanism. This finding implies that RTs are suitable for detecting temporal differences in color processing but, for that very same reason, rather ill-suited for reconstructing color spaces.

Adult↗
PubMed1995

[Study on color misnaming among the congenital color vision anomalous--Part 1. The tendency in color misnomer].

I report the hue and the color misnomers of 16 subjects with protanopia (color misnomers: 500) and 66 subjects of deutanopia (color misnomers: 2,056), and the color misnomers used by over 10 subjects each and their numbers. Green was the most frequent misnomer, followed by grey, yellow-green, purple, and brown. The deutanopia patients frequently used the Munsell color notation RP for grey. Many of the subjects who misnamed 11 times or more failed the Panel D-15 test. They were diagnosed as having strong color anomaly in the Ohkuma isochromatic plates and in the Tokyo Medical College isochromatic plates. The misnomers were most frequent among the neighboring hues. The severer the anomaly, the further the separation from the test color, and then the misnomers crossed the achromatic confusion line. Judging from the misnomer variation, the color sense of color anomaly does not necessarily seem to be constant. Moreover, liaison was noticed among red, brown, green, or occasionally purple in terms of misnaming pattern. Grey and pink were also linked in misnaming. Lightness was considered to play a strong role in these confusions.

Adolescent↗
PubMed1995

[Study on color misnaming among the congenital color vision anomalous--Part 2. Lightness and saturation of color misnomers].

I analysed the misnamed colors reported previously by plotting them on the value and chroma diagram. The study included at least 3 subjects for protanopia and at least 5 subjects for deutanopia on the same misnomer applied to one test color. The test colors were expressed by the Munsell color notation system. Deutanopia: High lightness value group (value 5 or more); Gr and lightly saturated G-->pink (test color-->misnomer), intermediately saturated YR and Y-->yellowish green, GY-->skin color, highly saturated GY-->orange, RP-->grey in wide range, lightly or intermediately saturated BG-->grey in many cases. Low lightness value group (value 4 or less); Gr-->green, lightly saturated Br-->green, intermediately saturated YR, GY, G and RP-->red, highly saturated R-->brown, YR-->green, intermediately saturated BG and B-->purple, intermediately saturated PB and P-->blue. Protanopia: RP-->red, PB-->purple, P-->pink, low lightness value lightly saturated BG-->black (this pattern was different from deutanopia), GY-->skin color (this pattern was shifted to the lightly saturated area), YR, Y-->green (more frequent in protanopia). YR, Y-->yellowgreen (more frequent in deutanopia). On the warm color side low sensitivity was anticipated not only for R but also for YR, Y, and GY. This anticipation will be substantiated by increasing the test subjects.

Color↗
PubMed1975

Prehatch color stimulation effects on color pecking preferences and color discrimination learning in white leghorn chicks.

Four experiments assessed the effects of stimulating chick embryos with colored light at 2 intensity levels. Both posthatch color pecking preferences (Experiments 1 and 2) and color discrimination learning (Experiments 3 and 4) were unaffected. These results affirm and extend a prior finding of no pre- and posthatch colored light stimulation effect on posthatch color preferences in ducklings. The color pecking preferences found replicated prior findings with chicks. However, they differed from the approach color preferences observed in color discrimination learning.

Animals↗
PubMed1999

Color stability and colorant effect on maxillofacial elastomers. Part I: colorant effect on physical properties.

STATEMENT OF PROBLEM: The average clinical life span of a maxillofacial prosthesis is approximately 6 months, at which point it needs to be refabricated, mainly because of degradation of the color and physical properties of the prosthesis. PURPOSE: This first part of a 3-part study evaluated the effect of coloring agents on the physical properties of maxillofacial elastomers. METHODS AND MATERIAL: Five dumbbell-shaped and 5 trouser-shaped specimens were fabricated for each of the combinations of the 3 elastomers (Silastic medical adhesive type A, Silastic 4-4210, and Silicone A-2186) and 6 colorants (dry earth pigments, rayon fiber flocking, artist's oil paints, kaolin, liquid cosmetics, and no-colorants), for a total of 180 specimens. Evaluations of hardness and tear strength were made with the trouser-shaped specimens. Evaluations of the ultimate tensile strength and the percentage elongation were made with the dumbbell-shaped specimens. A within elastomer analysis compared the 6 colorants using a 1-way analysis of variance for each of the 4 physical properties. When significant differences were observed, the Student-Newman-Keuls multiple range test was used to identify differences between groups at a significance level of.05. RESULTS: Physical properties of maxillofacial elastomers were changed by the incorporation of coloring agents. Dry earth pigments, kaolin, and rayon flocking acted as a solid filler without bonding to the Silicone, and artists' oils and liquid cosmetics acted as a liquid phase without bonding to the silicone matrix. CONCLUSION: No clearly superior colorant-elastomer combination was demonstrated in all the tests in this study.

Analysis of Variance↗
PubMedDate not supplied

Using a computer color-matching system in color reproduction of porcelain restorations. Part 2: Color reproduction of stratiform-layered porcelain samples.

Computer color matching is an excellent method for reproducing certain colors of various objects using a spectrophotometer and a computer. In this study the authors attempted to reproduce the color of layered porcelain samples according to the computer color-matching formulation, wherein a computer color-matched sample is made and compared with the target sample. The color differences between the computer color-matched samples (opaque/dentin and opaque/dentin/enamel) and the target samples approximated 1.0, and the samples were indistinguishable by visual observation. The spectral reflectance curves were also very similar.

Computer-Aided Design↗
PubMed1995

[Study on color misnaming among the congenital color vision anomalous--Part 3. Color misnomers and collation].

The test colors misnamed were grouped into two in their collation, i.e., R-G and BG-RP. Isochromatic collation was found in 75% of the subjects with normal color vision, 38.3% of those with protanopia, and 33% of those with deutanopia. In the hue collation isochromatic collation was seen most frequently, followed by neighborhood color collation. The more the misnomers, the further separated the hue collation, then the misnaming territory enlarged crossing over the achromatic confusion line, and the collation territory enlarged. The lightness collation was about equal between subjects with abnormal color vision and normal subjects. The former were inferior to the latter by 2% (deutan) and 4% (protan) in isosaturation collation. When the misnomer crossed the isochromatic line or collated near the white point, the date were analysed according to the color cunfusion theory. The subjects with abnormal color vision showed hue collation inferior to that of normal subjects, but they responded with twice the accuracy in the isochromatic collation than the misnomer collation, and the collation territory was narrow and simple.

Adult↗
PubMed1988

Categorical color perception: influence of cultural factors on the differentiation of primary and derived basic color terms in color naming by Japanese children.

Color naming tests with Japanese children (age 12-15) in Yonezawa, Tokyo and Düsseldorf (Germany) demonstrate that the primary basic color terms based on Hering's opponent color scheme are not influenced by the increasing Western cultural influence from Yonezawa to Tokyo and to Düsseldorf. The derived color terms for brown, orange and pink hues do appear to be influenced, however. The results support and extend the findings of Uchikawa and Boynton (1987). They verify the hypothesis that the psycholinguistics of color naming are based on a universal neurobiology of human color vision.

Adolescent↗
PubMed1958

Color defect and color theory; studies of normal and colorblind persons, including a subject color-blind in one eye but not in the other.

It is important to find answers to two questions concerning the visual discriminations of dichromatic persons, especially deuteranopes: (i) Do such persons show a loss of sensitivity to various wavelengths of the spectrum as compared with normal subjects? (ii) What colors do they see? A number of experiments were performed on the first question. First, luminosity curves were determined on three groups of subjects, consisting respectively of five protanopes, six deuteranopes, and seven normal individuals. As compared with normal subjects, protanopes show a loss of luminosity in the red, whereas deuteranopes show a loss in the blue-to-green region of the spectrum (See 10). Second, we examined the luminosity curves of a subject whose right eye is classifiable (on the basis of color-mixture determinations) as normal and whose left eye is classifiable as dichromatic. (The hue discrimination curve for her dichromatic eye seemed comparable to the curve of the usual deuteranope except in the violet, where it manifested relatively good discrimination.) The luminosity function for this subject's dichromatic eye, determined by data on threshold and flicker, exhibits the same type of luminosity loss in the blue and green regions of the spectrum as was shown by our group of six deuteranopes. Only unilaterally dichromatic subjects can tell us how colors seen by a dichromatic eye appear to a normal eye. In the color-blind eye, our unilaterally dichromatic subject sees wavelengths below and above her neutral ("grey") point (which occurs at 502 mmicro) as, respectively, a blue equivalent to about 470 mmicro and a yellow equivalent to about 570 mmicro in her normal eye. The results on (i) luminosity loss and (ii) the seeing of wavelengths above 502 mmicro as yellow are considered theoretically. The seeing of yellow by deuteranopes and protanopes may be accounted for by an idea based on Leber-Fick transmation theory. It is proposed that the characteristic sensitivities of the red and green receptors become similar while no change takes place in their central brain connections. Losses may be introduced into the transformed sensitivity curves to indicate appropriate degrees of luminosity deficit for deuteranopes and protanopes.

Color↗
PubMed1989

Partial color constancy of isolated surface colors examined by a color-naming method.

Color samples selected from the OSA Uniform Color Scales set were viewed without any surround. Separate light sources were used to illuminate the samples and to control the state of adaptation of the subject, thereby separating two factors that are normally confounded. A color-naming procedure was used to assess shifts in color appearance produced by altering the spectral distributions of one or both light sources. The results confirm that chromatic adaptation, when it is the only factor operating, can mediate partial color constancy.

Color Perception↗
PubMed1992

Influence of the Coanda effect on color Doppler jet area and color encoding. In vitro studies using color Doppler flow mapping.

We studied surface adherence and its effects on color Doppler jet areas and color encoding in an in vitro model with a noncompliant receiving chamber into which a steady flow jet was directed parallel to either a straight or a curved surface adjacent to and 4 mm away from the inflow orifice (1.50 mm2) with the control condition being a free jet matched for flow rates and driving pressures. Jets were imaged perpendicular to the plane of the surface, the plane in which most clinical images of jet-surface interactions are obtained. Ten different flow rates ranging from 0.13 to 0.30 l/min were used. Surface-adherent jet areas were smaller than control jets for every driving pressure-volume combination (paired t test, p less than 0.01). Computer analysis of color Doppler images showed more green and blue (reverse flow) pixels on the surface side of the adherent jets than the control jets (p less than 0.05), suggesting that viscous energy loss and flow deceleration and reversal play a role in the jet-surface interaction. Analysis of variance demonstrated that linear regression slopes of flow rate versus jet area for surface jets were lower (slopes, 11-21 cm2/l/min; r = 0.95-0.97) than those for the control (slope, 33 cm2/l/min; r = 0.97) (p less than 0.0001). Surface adherence (Coanda effect) influences jet size and color encoding, causing smaller color Doppler jet areas and greater variance and reverse velocity encoding.

Coronary Circulation↗