Visibility of durable fluorescent materials for signing applications

Increasing visual complexity in the roadway environment is making the task of driving a greater challenge for the motorist. Recent advances make it possible to produce fluorescent retroreflective materials suitable for long-term outdoor signing applications. This article presents the results of a field study investigating the relative advantage of fluorescent colors over standard colors for detection, color recognition, and conspicuity against a complex dark background. These fluorescent retroreflective materials are detected with higher frequency, and recognized with greater accuracy at further distances than the corresponding standard highway colors. They also have greater attention-getting properties (more conspicuous) during daylight than the corresponding standard highway colors. The luminance contrast ratio of the sample to the camouflage background appears to correlate with the visibility/conspicuity results obtained in this study, particularly within a given color series. © 1995 John Wiley & Sons, Inc.     

Interior and exterior daylight illuminants for the colorimetry of fluorescent materials

The difficulties in simulating CIE Standard Illuminant D₆₅ are considered and an interior daylight illuminant is described, Illuminant ID₆₅, representing exterior daylight attenuated by average window glass. The benefits of Illuminant ID₆₅ are that it represents the daylight source which most commonly occurs in the viewing of critically coloured merchandise, and that it can be practically simulated using a filtered tungsten-halogen source. Its applicability to measurements, particularly to the assessment of fluorescent samples, is considered. The results of measurements on the two common classes of fluorescent samples are discussed and indicate that an Illuminant ID₆₅ simulator can be used validly for the measurement of fluorescent materials, even including materials intended specifically for exterior use.     

Simulation of daylight for viewing and measuring color

For convenience and reproducibility, daylight is artificially simulated for viewing and measuring colors. Daylight has been standardized in a way that is impractical. the evaluation of fluorescent materials requires simulation of the ultraviolet component of daylight or daylight through a window. Sources for viewing are assessed by spectroradiometry and standard computations. Sources for spectrophotometry may be tested the same way or by measuring radiance factors of fluorescent standards. Better manufacturing methods have improved glass filters. A new filter design method takes account of the spatiospectral nature of the source and affords many degrees of freedom.     

Practical method for measuring printed colors on FWA‐treated paper

The virtual fluorescent standard (VFS) method is a new approximation method for the practical measurement of the colorimetric properties of an object treated with fluorescent whitening agent (FWA). The essential requirement of the VFS method is that the bi‐spectral characteristics of the VFS must be similar in curve shape to those of the object to be measured. In the case of an object printed on an FWA‐treated substrate, the bi‐spectral characteristics will vary depending on not only the substrate but also the printed ink films. In this study, two simplified VFS methods, one using the bi‐spectral characteristics of the substrate and the other using those of typical paper as the VFS instead of those similar to each object, were evaluated. The evaluation was performed using two instrument models for the VFS method with the different illuminations with five sets of 13 samples printed in different colors by five different printer/paper combinations. In this evaluation, the total spectral radiance factor of each sample was obtained by simulated measurement, that is, it was calculated based on the bi‐spectral radiance factor of the sample and the spectral power distributions of the light source of the instrument. The total spectral radiance factor of each sample under D50 obtained using both VFS models and CIE L*a*b* values derived therefrom were compared with those by the reference model with ideal D50 illumination. Although the samples are limited, the results shows that both simplified VFS methods remarkably reduce the errors due to fluorescence when compared to the conventional method. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2012     

Optimization of a spectrally tunable LED daylight simulator

Daylight simulators (i.e., D50, D55, D65, and D75 simulators) play an important role for industrial applications, such as surface color industry, recipe formulation, and graphic arts industry. Conventional light sources, including xenon lamps, tungsten‐halogen lamps, and fluorescent lamps, have been used as daylight simulators. In this article, a genetic algorithm is employed to investigate optimized channels for each daylight simulator. It is found that at least six LED channels are required to produce high quality daylight simulators in terms of the CIE Metamerism Indices. Furthermore, it is possible to create a spectrally tunable daylight simulator using six LED channels with wavelengths of 357, 420, 474, 533, 595, and 660 nm. This wavelength combination with appropriate intensity combinations can produce D50, D55, D65, and D75 simulators with good performance, in terms of the CIE Metamerism Indices. The color appearance of various color samples or objects under such a daylight simulator is found to be very similar to those under a corresponding daylight illuminant. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 419–423, 2017     

Measurement and assessment of substrates containing fluorescent whitening agents

White, as a color sensation, can be determined by colorimetric methods of measurement. With other than colorimetric methods, no satisfactory correlation between measured value and visual assessment can be expected. The contribution of hue, saturation and luminosity to the degree of whiteness as found by six formulas widely used in industry was analyzed and the results were plotted in the form of a graph. An easy-to-use nomogram for whiteness determination was developed, based on the CIE 1931 2°-color system. Another nomogram is presented which provides an easy means to determine the hue of a sample treated with fluorescent whiteining agents (FWAs). The new whiteness determination is based on the measurement of true tristimulus values for fluorescent samples using the new International Commission on Illumination standard illuminant D 65. The magnitude of the just perceptible difference in whiteness was determined in a panel test using 11 samples and 22 observers. The results were evaluated statistically. Pending standardization of an illuminant, not only for colorimetric measurements, but also for visual assessment of white samples containing FWAs, it would scarcely seem possible to arrive at a more accurate determination of degrees of whiteness. All visual rankings of fluorescent white substrates are widely scattered around a mean value for the different phases of natural daylight. The relative energy emitted by artificial daylight lamps in the near UV region is insufficient in many cases. Xenon lamps are quite satisfactory for instrumental evaluation. In an internationally approved system, with a known hue preference, it would be possible to compare an objective measured value with each subjective result obtained by visual evaluation.     

Colorimetry of durable fluorescent retroreflective materials

The development of durable daylight fluorescent retroreflective sheetings has led us to investigate some of the factors that influence color measurement of these materials. the colorimetry of retroreflective materials is particularly sensitive to measurement geometry. the added aspect of fluorescence increases the spectral uncertainties, making appearance measurements even more difficult. the visual properties used to describe fluorescent retroreflective materials should include chromaticity, lightness, peak spectral radiance factor, nighttime color, and color stability on exposure. A number of test methods exist for these measurements; however, practical experience in applying these methods to fluorescent materials shows significant variation in the resulting measured values. Colorimetric measurements on commercial instruments using 45/0 (0/45) geometry, a simulated D65 illuminant, and the CIE 2° standard observer yield results that are inadequate for precise quality control of durable fluorescent retroreflective materials. the uncertainty can be reduced by the use of transfer standards, provided that the standard is similar to the sample in both hue and fluorescent emission. Ultimately, the wide availability of commercial 2-monochromator spectrocolorimeters will be required. © 1995 John Wiley & Sons, Inc.     

Optimization of a spectrally tunable daylight simulator using four quantum dot light-emitting diodes for visual appraisal of color

An optimization model for luminous efficacy of a spectrally tunable light-emitting diode (LED) daylight simulator under constraint of metamerism index was developed. It was first reported that the optimal spectrally tunable LED daylight simulator of AA grade for D50, D55, D65, and D75 standard illuminants could consist of two quantum dot-integrated LEDs (QDLEDs) with the ultraviolet chip and two other QDLEDs with the blue chip. The optimized spectral parameters of each QDLED, as well as photometric and colorimetric performances of D50, D55, D65, and D75 daylight simulators, were obtained by maximizing luminous efficacy under the metamerism index for both a visible and ultraviolet range less than 0.25. The limit luminous efficacies of four daylight simulators using four QDLEDs under the ideal case will reach 181 lm/W to 205 lm/luminous efficacies with a radiant efficiency of both the ultraviolet and blue chips of 60%, as well as a quantum efficiency of a quantum dots layer of 90%, will reach 100 lm/W to 112 lm/W.     

Total Acid Number Determination of Biodiesel and Biodiesel Blends

The repeatability and accuracy of the total acid number (TAN) measurement for soy oil-based biodiesel–diesel blends using the ASTM D664 method was studied. ASTM D664 is the standard reference method for measuring the acid number of both biodiesel and petroleum-derived diesel, which specifies procedures for the determination of acidic components in biodiesel and diesel, and claims good repeatability and mediocre reproducibility during application, but cites no information on accuracy. However, the accuracy of this method is very important for setting the specifications for biodiesel blends, especially for B20 (a mixture composed of 20% biodiesel with 80% diesel) because of its wide commercial production. The accuracy of ASTM D664 was measured to be within 4.13% for B20 in the acid number range of 0.123–0.332 mg KOH/g. The maximum repeatability was approximately 5.21% at an acid number of 0.123 mg KOH/g. Within the ASTM D6751-07b specification for TAN (0.5 mg KOH/g), good accuracy and repeatability were also obtained. Accuracy specification and electrode operation suggestions for ASTM D664 are also given.     

Repeatability,reproducibility, and accuracy of a novel pushbroom hyperspectral system

This study analyzes the repeatability, reproducibility and accuracy of a new hyperspectral system based on a pushbroom sensor as a means of measuring spectral features and color of materials and objects. The hyperspectral system consisted of a CCD camera, a spectrograph and an objective lens. An additional linear moving system allowed the mechanical scanning of the complete scene. A uniform overhead luminaire with daylight configuration was used to irradiate the scene using d:45 geometry. We followed the guidelines of the ASTM E2214‐08 Standard Practice for Specifying and Verifying the Performance of Color‐Measuring Instruments that define the standards and latest multidimensional procedures. The results obtained are analyzed in‐depth and compared to those recently reported by other authors for spectrophotometers and multispectral systems. It can be concluded that hyperspectral systems are reliable and can be used in the industry to perform spectral and color readings with a high spatial resolution. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 549–558, 2014     

新型5-羧基-磺酸基罗丹明的微波合成及对蛋白质的标记作用

利用微波加热技术,以2-磺基-4-羧基苯甲醛和N,N-二烷基-3-氨基酚为原料,在空气气氛中,合成了3种结构新颖的反应性荧光染料———5-羧基-磺基罗丹明类化合物。通过荧光光谱的测定,对5-羧基-磺酸基罗丹明-链霉亲和素复合物与TAMRA和Texas Red-链霉亲和素复合物的荧光强度进行对比分析。结果发现,5-羧基-磺基罗丹明类化合物与链霉亲和素共价结合后,产生强荧光,比目前常用的荧光标记染料更适宜用于标记蛋白质。     

Thermochromism of fluorescent colors

Fluorescence (sometimes called rapid luminescence or just luminescence) has been scientifically studied for 150 years. Recent advances in daylight simulators, ultraviolet filters, and measurement devices (for example, advances in the commercial two‐monochromator measurement devices) have made it possible to study this phenomenon more accurately. Many factors affect the color of a fluorescent object. One of these factors is the temperature of the sample. It is known that, for example, the reflectance of the nonfluorescent ceramic color reference tiles used for calibration of colorimeters and spectrophotometers is temperature dependent. This phenomenon is called thermochromism, which means a reversible change of a color of the sample as a function of temperature. The phenomenon can also be detected in fluorescent colors, although fluorescent samples show quite different thermochromic properties that have not been extensively studied and are partly unknown. In this article we first discuss the thermochromism of nonfluorescent samples. We consider the meaning of thermochromism for fluorescent color measurements. Novel experimental data are provided and the temperature‐dependent changes in samples' radiance spectra are analyzed and proven to be significant. In some fluorescent samples the thermochromic changes can be as high as 4 times the thermochromic changes in some nonfluorescent samples in the same temperature scale (e.g., red fluorescent paint sample versus red ceramic sample, with equivalent temperature changes). In addition, a two‐component thermochromic model is introduced to discuss the phenomenon of thermochromism more closely. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 163–171, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20104     

Lightfastness of pigmented handmade papers

Artists are making pigmented handmade papers in increasing numbers to be certain that the color of the paper is lightfast. The lightfastness of handmade papers colored with commonly used pigments was tested. Three methods were used: (1) exposure to a measured 1260 MJ/m² outdoors to the sun under glass; (2) exposure in the laboratory to daylight fluorescent lamps; and (3) exposure in a window monitored by Blue Wools. Burnt umber and the yellow and red iron oxides were lightfast as expected. Excellent, or sufficiently lightfast, were Pigment Yellow 65 and the lightfast form of Pigment Yellow 74, the phthalocyanine blue and green, ultramarine blue, and the Quinacridone reds if used in sufficiem strength. If the Quinacridones were weaker they were classified as Good in lightfastness along with Pigment Yellow 97. Classified as Fair were the higher-strength form of Pigment Yellow 74 and the naphthol red with AS-D coupling. Unsatisfactory, or fugitive, were the lithol and toluidine reds, weaker use of the higher-strength form of Pigment Yellow 74, and an unidentified organic yellow pigment.     

A VISUAL APPROACH TO CONTROLLING METAMERISM

Although it is emphasized that the proper practical approach to minimizing metamerism in industrial coloring processes is through spectrophotometry, rules are developed for selecting and, if necessary, blending colorants to control metamerism through a purely visual approach. Examples are taken from the vinyl plastics industry, and it is assumed that the match is to be made with a black, a white, and two chromatic pigments. With the approximate hues of all available chromatic pigments marked on a simple hue circle, a trial match to the standard is made. Rules are developed and illustrated for altering the selection of chromatic pigments to reduce metamerism, based on the change in color of the trial match relative to that of the standard as the light source is changed from daylight to tungsten or fluorescent light. With practice, compositions which are good visual matches to the standard in all three sources can be obtained.     

Evaluation of methods for verifying the performance of color‐measuring instruments. Part I: Repeatability

A recent ASTM specification (ASTM E2214‐02) was created to standardize the terminology and procedures used to evaluate color measuring instruments. This specification addresses the need for uniformity among the manufacturers of such instruments when quantifying the performance of their products. The scope of E2214 is necessarily large, covering the procedures required to compare instruments for a variety of metrics, all of which are important to their overall performance. In this work, we will focus on one aspect of the instrument evaluation: repeatability performance. We will present repeatability results from a long‐term study of twelve commercial spectrophotometers. Comparisons will be made between traditional color difference metrics and the more complex multidimensional methods specified in E2214. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 166–175, 2007     

Prediction of emission spectra of fluorescence materials using principal component analysis

Fluorescent materials are now a critical field of research due to their unique excitation and emission properties that can be tailored to specific fluorescence detection technologies. In this work, a procedure is described to approximate the emission spectral data of fluorescent materials of different types from their excitation spectral data using principal component analysis (PCA) technique. First, PCA as a statistical and mathematical method was used to reconstruct the excitation and emission spectra of training dataset and then, the approximation was accomplished by multiple linear regression (MLR).The performance of obtained function was examined on testing dataset. Afterward, CIE tristimulus values of the fluorescent samples were calculated based on ASTM, E2152–12 standard test method. The colorimetric accuracy was then evaluated by calculating the geometric differences in CIE tristimulus values X, Y, and Z for the 1964 standard colorimetric observer under illuminant D65. The obtained results show a good curve fit between the actual emission spectra and recovered emission spectra. In addition, based on cumulative variance and root mean square (RMS), eight principal components were selected as optimum number of principal components for prediction of emission spectra data. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 16–21, 2016     

A poly(alkylsulfany)thiophene functionalized with carboxylic groups

Different routes, based on the Stille coupling, to the obtainment of a polythiophene bearing a carboxyhexylsulfanyl chain every two thiophene rings (PTCOOH) are here reported and discussed. Two PTCOOHs with different chain lengths were obtained: the shorter by hydrolysis of a polymeric ester precursor and the longer by direct Stille coupling from suitable monomers. They possess similar electrochemical properties but behave differently when aggregation and fluorescence are concerned. The PTCOOH obtained by hydrolysis is found to be fluorescent in a good solvent such as THF, and its fluorescence quantum yield decreases as the extent of aggregation increases. The polymer obtained by direct Stille coupling is less fluorescent, consistently with its proneness to aggregate. The PTCOOH obtained by hydrolysis is therefore more promising in view of the build-up of solid-state devices with exploitable fluorescence properties.     

Calorimetric thermal conductivity measurement for high-temperature materials

A K1952 instrument has been upgraded to determine the thermal conductivities of materials by the GOST 12170 stationary method. The application of that method has been extended to the determination of thermal conductivity for industrial forms of refractory materials and for research in material science, design, and thermal insulation calculation. The K1952 system has been used in testing standard specimens. It has been confirmed that the parameter measurements conform to the technical documentation for standard specimens. A certificate has been obtained to confirm the type of means of measurement RU. E.32.001.A No. 30197, which was issued by the Federal agency on technical regulation and metrology. Translated from Novye Ogneupory, No. 2, pp. 47 – 49, February, 2009.     

基于氮掺杂碳量子点的荧光微球制备和Fe3+检测

分别以尿素、氨水、二乙烯三胺、多乙烯多胺为氮源,绿色廉价的白菜为碳源,采用水热法合成氮掺杂的蓝色荧光碳量子点,结果表明多乙烯多胺氮掺杂碳量子点（NCDs）荧光量子产率最高为53.3%。然后将NCDs作为荧光探针应用于荧光微球制备和Fe³⁺检测方面,以三聚氰胺甲醛（MF）为载体,合成了氨基化MF荧光微球;基于Fe³⁺对NCDs良好的荧光猝灭效应,建立了一种荧光测定Fe³⁺的方法,并对NCDs和MF荧光微球的结构和性能进行表征。结果表明,NCDs的荧光性能得到了显著的改善;MF荧光微球单分散性好、荧光性能好且稳定,在生物医学领域方面有重要的应用价值;NCDs对Fe³⁺具有单一选择性,Fe³⁺浓度在0~2μmol/L内与NCDs的荧光猝灭程度呈良好的线性关系（R²=0.9945）,检出限为0.035μmol/L。将该体系应用于实际水样中Fe³⁺的测定,相对标准偏差（RSD,n=6）在1.42%~3.02%内,加标回收率在98.7%~104.5%之间。该体系对Fe³⁺检测灵敏性好、选择性高以及抗干扰性强,在离子分析检测方面有潜在的应用前景。     

Red fluorescent protein variants with incorporated non-natural amino acid analogues

Fluorescent proteins are important tools in biotechnology applications and biosensing. DsRed, a red fluorescent protein, has expanded the colors of fluorescent proteins beyond the more commonly used green fluorescent protein. Many genetic modifications have been performed on DsRed to overcome some of its drawbacks. These primarily focused on overcoming the oligomerization detrimental to DsRed activity, and the parasitic green fluorescence caused by the immature chromophore. One such variant, DsRed-monomer, has minimal green fluorescence and no oligomerization. A few traditional mutagenesis studies have been done with DsRed and its mutants to shift the fluorescence wavelengths creating additions to the pallet of fluorescent protein colors. We have explored incorporation of non-natural amino acid analogues into DsRed-Monomer, obtaining variants with differing emission properties. In this work, two such analogues of tyrosine have been incorporated into DsRed-Monomer: 3-amino-l-tyrosine and 3-fluoro-l-tyrosine. Tyrosine analogues were chosen due to the role of tyrosine in the formation and structure of the protein's chromophore. The variants obtained in our study showed altered emission wavelengths and spectral characteristics. Our study demonstrates that incorporation of non-natural analogues into DsRed-Monomer is a viable approach to alter the spectral characteristics of the protein. We envision that this study will open up the door to non-natural mutagenesis studies with red fluorescent proteins and its mutants.