Faculty Opinions recommendation of Modified DNA analogues that sense light exposure with color changes.

ABSTRACTThis paper describes the five-year Lightfastness Correlation Project that I am conducting in sixteen institutions in the US and Western Europe, with the support of the Samuel H. Kress Foundation.Dr. Robert L. Feller, a scientist at the National Gallery of Art, published several papers in the 1970s in which he speculated that a certain duration of time could be correlated, in a general way, to the color changes noted in the Blue Wool Textile Fading Cards. Museums use the cards as inexpensive dosimeters, put somewhere in a gallery along with the art. Enough is known about their behavior to have confidence in their ability to indicate when it is time to remove an object from exhibition.The Blue Wools are also used in two Standards developed by ASTM International’s Subcommittee D01.57 on Artists’ Paints and Related Materials. ASTM D 5383 and ASTM D 5398 are simple lightfastness test methods. In them, the Blue Wool cards are exposed to natural daylight along with any colored material, and are used to tell the artist when it’s time to stop the test and as a rating device.Another ASTM Standard from D01.57, ASTM D4303, uses instruments to control the accumulated amount of natural daylight, or simulated daylight in a xenon arc light exposure machine. It also uses a spectrophotometer to calculate the color change that can occur in a test sample, expressed in CIE L*a*b*. There is also a standard formula for calculating color change that results in a single number, expressed as Delta E, or ∆E.The ∆E number is used by ASTM D01.57 to assign lightfastness ratings to artists’ coloring materials covered by its Specifications for various products. Initial development of the ASTM methods began in 1977; we have 33 years of data that confirms the worth of the methods used in our testing.What is the relationship between the results of Blue Wool testing and the results using D01.57’s technical ∆Es? This is a fundamental question we have yet to thoroughly examine. We have begun to work on the problem, using accelerated natural and artificial light sources as in ASTM D 4303. But no one has ever tried to compare the results of these two test methods in a museum environment, over an extended period of real time.“The Lightfastness Correlation Project” ends in August 2011, and a final scientific report will be submitted to the sponsor, The Samuel H. Kress Foundation, in September 2011.

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The effects of ultraviolet and visible light on common furs: Color changes, photooxidation and the use of Tinuvin 292 as a photoprotectant

Collection Forum ◽

10.14351/0831-4985-30.1.15 ◽

2016 ◽

Vol 30 (1-2) ◽

pp. 15-33

Author(s):

Corina E. Rogge ◽

Anya Shullman

Keyword(s):

Visible Light ◽

Uv Radiation ◽

Light Exposure ◽

Mechanical Damage ◽

Attenuated Total Reflectance ◽

Preventative Treatment ◽

Total Reflectance ◽

B Values ◽

Color Changes ◽

Induced Changes

Abstract In order to determine the light sensitivities of commonly encountered furs, 17 furs from 12 species were exposed to 1.97 Mlx hours of light from a xenon arc lamp, filtered either to simulate window-filtered daylight or to remove all ultraviolet (UV) radiation. Comparison with coexposed Blue Wools showed that most samples were relatively lightfast (Blue Wool 5 or better), with darker specimens being more lightfast. Examination of the Commission internationale de l'éclairage (CIE) L*a*b* values revealed fading but also other changes: some furs darkened, and other experienced changes in b* values. Removal of UV radiation prevented darkening and usually decreased the magnitude of ΔE76 but did not prevent color changes, and one species exhibited greater change under visible light. Changes in color were accompanied by photooxidation of the keratin of all species as assessed by attenuated total reflectance infrared spectroscopy; the extent of photooxidation was decreased by filtering out UV radiation. Pre-exposure treatment with a spray application of a 1% solution of Tinuvin 292, a hindered amine light stabilizer, offered some protection against both UV and visible light-induced changes. Tinuvin 292 pre-exposure also helped prevent keratin photooxidation and light-induced mechanical damage and thus may be an appropriate preventative treatment when light exposure is unavoidable.

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Colored Paints Containing NIR-Reflective Pigments Exposed to Accelerated Ultraviolet Radiation Aging with Possible Application as Roof Coatings

Coatings ◽

10.3390/coatings10111135 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1135

Author(s):

Stefano Rossi ◽

Hampus Lindmark ◽

Michele Fedel

Keyword(s):

Near Infrared ◽

Light Exposure ◽

Maximum Temperature ◽

Potential Candidate ◽

Light Spectrum ◽

Ir Camera ◽

Color Changes ◽

The Difference ◽

Steel Panels ◽

The Stability

This study aims to evaluate the difference in thermal behavior among paints with the presence of traditional and NIR pigments by means of a simple and cheap laboratory-scale test. Considering these goals, the thermal and esthetical properties of two different cool coatings were assessed, highlighting their positive and limited aspects. Two different complex near-infrared inorganic reflective (NIR) pigments with yellow and black respectably colors were mixed in an acrylic waterborne copolymer binder. The paint formulations were applied on steel panels. The thermal performance of the coatings was investigated in the NIR-region of the light spectrum by exposing the samples to an IR-lamp. The outer and inner surface temperatures of the painted panels were recorded using thermocouples and an IR camera. The samples were aged by artificial UV-B light exposure. Color and specular gloss changes at different exposure times were evaluated. The behavior of the cool coatings was compared with that of conventional coatings with similar color characteristics. The black cool coating achieved a maximum temperature decrease, compared to the conventional black one, of approximately 12 °C. The stability for the cool coatings was very similar to that of the conventional coating, indicating that black pigment could be a potential candidate for cool-coating applications. The yellow cool coatings did not show a significant decrease in temperature compared to the conventional paint. The gloss and color changes resulted as influenced by the types and amount of pigments.

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Comparison on the Aging of Woods Exposed to Natural Sunlight and Artificial Xenon Light

Polymers ◽

10.3390/polym11040709 ◽

2019 ◽

Vol 11 (4) ◽

pp. 709 ◽

Cited By ~ 2

Author(s):

Ru Liu ◽

Hanwen Zhu ◽

Kang Li ◽

Zhong Yang

Keyword(s):

Color Change ◽

Light Exposure ◽

Early Stage ◽

Tectona Grandis ◽

Sunlight Exposure ◽

Light Sources ◽

Natural Sunlight ◽

Color Changes ◽

Xenon Light ◽

Aging Stage

To investigate the relationship between sunlight and artificial light sources on the weathering of wood, three woods, namely, Tectona grandis L.F. (teak), Stereospermum colais (mabberley), and Dicorynia guianensis (basralocus), were tested under natural sunlight for 733 days and artificial xenon light for 180 h, respectively. A comparison between sunlight and artificial xenon light was made based on surface color changes at various intervals. The results showed that the woods suffered from more severe aging in the artificial xenon light exposure than that in the natural sunlight exposure. At the early stage of exposure, very good relationships were found between 70 days under natural sunlight weathering and 60 h under artificial xenon light weathering. Compared with natural sunlight, about a 30 times faster aging process was identified in the artificial xenon light. However, the linear relationship vanished at the later aging stage. It was found that the color change fluctuated in natural sunlight, while it increased steadily in artificial xenon light. The wood species affected the aging of woods. In natural sunlight exposure, the color change decreased in the order of mabberley > teak > basralocus, while in artificial xenon light exposure, color change decreased in the order of mabberley > basralocus > teak due to the easier volatilization of extractives in artificial xenon light than in natural sunlight.

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Photostabilizers performance on the surface analysis of green composites

Polymers and Polymer Composites ◽

10.1177/0967391120901620 ◽

2020 ◽

Vol 29 (1) ◽

pp. 57-64

Author(s):

Hasret Ece Sönmez ◽

Mehmet Safa Bodur ◽

Alper Adrian Baysan ◽

Mustafa Bakkal ◽

Ersin Serhatli

Keyword(s):

Surface Analysis ◽

Color Change ◽

Uv Light ◽

Light Exposure ◽

Accelerated Weathering ◽

Reinforced Composites ◽

Color Changes ◽

Photodegradation Mechanism ◽

Ldpe Composites

In this work, various stabilizers have been introduced to prevent or delay degradation due to ultraviolet (UV) light exposure to prolong the service life of cotton fiber-reinforced composites. The effect of various additives like hindered amine light stabilizer, UV absorber (UVA), and antioxidant as photostabilizers of CF/low-density polyethylene (CF/LDPE) composites was compared. We showed how they influence to delay or eliminate the photodegradation of CF/LDPE subjected accelerated weathering. Surface analysis was performed by Fourier transform infrared spectroscopy and color measurements. The results showed us the insight of the photodegradation mechanism of weathered CF/LDPE composites undergoing photooxidative reactions which causes a loss surface quality such as micro-cracking and color change. Among the stabilizers, UVA was found to be the most effective to delay some color changes in long term.

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Effects of Changes in Colored Light on Brain and Calf Muscle Blood Concentration and Oxygenation

The Scientific World JOURNAL ◽

10.1100/tsw.2011.118 ◽

2011 ◽

Vol 11 ◽

pp. 1216-1225

Author(s):

J. Weinzirl ◽

M. Wolf ◽

P. Heusser ◽

M. Nelle ◽

U. Wolf

Keyword(s):

Blue Light ◽

Blood Volume ◽

Near Infrared ◽

Light Exposure ◽

Red Light ◽

Light Therapy ◽

Calf Muscle ◽

Sequential Order ◽

Color Changes ◽

The Brain

Color light therapy is a therapeutic method in complementary medicine. In color therapy, light of two contrasting colors is often applied in a sequential order. The aim of this study was to investigate possible physiological effects, i.e., changes in the blood volume and oxygenation in the brain and calf muscle of healthy subjects who were exposed to red and blue light in sequential order. The hypothesis was that if a subject is first exposed to blue and then red light, the effect of the red light will be enhanced due to the contrastingly different characteristics of the two colors. The same was expected for blue light, if first exposing a subject to red and then to blue light. Twelve healthy volunteers (six male, six female) were measured twice on two different days by near-infrared spectroscopy during exposure to colored light. Two sequences of colored light were applied in a controlled, randomized, crossover design: first blue, then red, and vice versa. For the brain and muscle, the results showed no significant differences in blood volume and oxygenation between the two sequences, and a high interindividual physiological variability. Thus, the hypothesis had to be rejected. Comparing these data to results from a previous study, where subjects were exposed to blue and red light without sequential color changes, shows that the results of the current study appear to be similar to those of red light exposure. This may indicate that the exposure to red light was preponderant and thus effects of blue light were outweighed.

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Exploring the Potentialities of Photoinduced Glycation to Steer Protein Functionalities: The Study Case of Freeze-Dried Egg White Proteins/Carbohydrates Mixtures

Foods ◽

10.3390/foods10010026 ◽

2020 ◽

Vol 10 (1) ◽

pp. 26

Author(s):

Lara Manzocco ◽

Stella Plazzotta ◽

Sonia Calligaris

Keyword(s):

Particle Size ◽

Foam Stability ◽

Light Exposure ◽

Critical Concentration ◽

Fold Increase ◽

Egg White ◽

Color Changes ◽

Freeze Dried ◽

Egg White Proteins ◽

Uv C

The capacity of UV-C light to induce glycation and modify functional properties of systems containing freeze-dried egg white proteins and carbohydrates with increasing molecular weight (i.e., glucose, maltose, trehalose and maltodextrin) was studied. Color changes induced by light exposure were taken as typical indicators of glycation. Samples were then analyzed for selected physical (critical concentration, particle size and viscosity), chemical (ovalbumin content) and technofunctional properties (gelling temperature and foaming capacity). The presence of sugars during exposure to UV-C light promoted intense browning and decreased ovalbumin content by circa 30%. Concomitantly, up to a 3-fold increase in critical concentration of the aqueous suspensions of the irradiated protein-carbohydrate powders and changes in particle size were detected. These modifications were consistent with the development of non-enzymatic browning reactions upon UV-C light irradiation. Photoinduced glycation was associated to a decrease in viscosity, a tendency to form gel at temperature lower by up to 8 °C and a better capacity of foam stabilization. The intensity of these changes seems to be affected by the nature of the carbohydrates reacting with proteins, with longer carbohydrates able to produce systems with higher foam stability capacity.

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