The multiwavelength excitation (MWE) method for measuring the colorimetric properties of fluorescent whitening agent (FWA)-treated specimens illuminated by a standard daylight illuminant computationally approximates not the spectral power distribution (SPD) of the illuminant but the luminescent SPD excited thereby by a weighted sum of the luminescent SPDs excited by a few different narrow-band illuminations. The weights are optimized for the actual SPDs of those illuminations and the bispectral luminescent radiance factors of typical FWA-treated paper specimens. Since the latter is invariant among instruments once provided as the common numerical data, the variations of the narrow-band SPDs give major impacts to the reproducibility of this method. The weights optimized for the varied SPDs, however, mitigate the impacts. For investigating how they impact, one basic illumination system and its 16 simple variation systems were built virtually. The basic system consists of three narrow-band LEDs and one blue-excited white LED, whereas the individual simple variation system has either the peak wavelength or spectral width of one of the four LEDs (including the blue LED in the white LED) varied. With those systems, seven FWA-treated papers with the known bispectral radiance factors were measured computationally by simulating the procedure of the MWE method. The differences in the colorimetric values measured with the simple variation systems from those with the basic system are far below the just noticeable difference, which indicates that the MWE method can be a practical solution for better reproducibility in measuring FWA-treated papers.

Measurements by spectrophotometers more or less suffer from heterochromatic stray light generated in their spectrometers. It is divided into near-band and off-band stray lights. While the former appears near the spectral band of the incident flux, the latter distributes broadly across the whole range and is far more problematic from colorimetric point of view. This article presents a practical method for correcting off-band stray light in dual-channel array spectrographs often built in modern spectrophotometers. Unlike most correction methods using a line spread function, the presented method estimates the distribution of off-band stray light across the array as the product of a device-specific stray light distribution and a total stray light intensity. The latter depends on both the spectral power distribution of an incident flux and a device-specific rate of change from the incident flux to the off-band stray light. For further simplification, the method replaces wavelengths by several bands dividing the visible range owing to the moderate spectral dependence of the above rate of change. With those simplifications, the method is practical, effective, and robust enough to work in an inexpensive hand-held spectrophotometer with the compact spectrograph which often suffers from off-band stray light. The performance of the method was evaluated with two dual-channel array spectrographs with and without 2nd-order-rejection filter. Specimen lights incident through ten different glass filters were measured and the errors caused by off-band stray light in the pixel outputs from the array were successfully corrected by the method. (C) 2016 Wiley Periodicals, Inc.

Colorimetric properties of fluorescent materials depend on the SPD of the illumination. That is why most standards for evaluating them specify the illuminations, which are often hard-to-realize daylight illuminants. The presented method using commercially available LEDs enables accurate enough colorimetric measurements of FWA-treated papers or prints on them illuminated by the specified illuminant. The total spectral radiance factor of a fluorescent specimen, from which most colorimetric values are derived, consists of the luminescent spectral radiance factor and the spectral reflectance factor. This method separately estimates those of FWA-treated paper to add up to the total spectral radiance factor. The luminescent spectral radiance factor is obtained by estimating the SPD of luminescence excited by the specified illuminant as the weighted sum of the multiple SPDs of luminescence excited by the respective narrow band LED emissions at different wavelengths. The LEDs and their weights are determined optimally for generally used papers. The spectral reflectance factor is derived from the estimated SPD of the radiation with fluorescence excluded from the paper illuminated by visible illumination. The method was applied with five different illumination systems each using two or three narrow band LEDs in the excitation range. They were evaluated by measuring the total spectral radiance factors by D50 of seven FWA-treated papers and CMYK prints on four papers. The derived colorimetric values were compared to the respective references by the ideal D50.

Numerical corrections of colorimetric errors caused by positioning error and irregular geometry in multiangle measurements of gonio-apparent coatings are presented. These corrections use a model function approximating the gonio-reflection characteristics of the coating to convert the angular displacement due to those geometric errors to reflectance factor errors to be corrected as well as to estimate the angular displacement conversely from the reflectance factors. The performance of these corrections was evaluated for 11 different gonio-apparent coatings using a multiangle geometry conforming to ASTM E2539 consisting of eight subgeometries to which artificial displacements were applied so as to present typical positioning errors or irregular geometries. The results show that both corrections significantly reduce the colorimetric errors for all specimens in all subgeometries sensitive to geometric errors. (c) 2015 Wiley Periodicals, Inc. Col Res Appl, 2015

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 there-from 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. (C) 2011 Wiley Periodicals, Inc. Col Res Appl, 37, 168-175, 2012; Published online 13 July 2011 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/col.20677

In animal models of degenerative lumbar disease, inducible nitric oxide synthase (iNOS) is expressed in macrophages and Schwann cells following compression of the cauda equina. We previously reported that NO metabolites (nitrite plus nitrate: [NOx]) in the cerebrospinal fluid (CSF) correlate with postoperative pain relief in patients with degenerative lumbar disease and with neurologic recovery rate postoperatively or after conservative treatment in patients with spinal cord injury. The objective of the present study was to examine the relationship between [NOx] and neurologic severity, and recovery in degenerative cervical and lumbar diseases. Two hundred fifty-seven cases, including 85 patients with cervical compression myelopathy (CCM), 25 with cervical disc herniation (CDH), 70 with lumbar canal stenosis (LCS), and 77 with lumbar disc herniation (LDH), were examined. The CSF [NOx] was measured using the Griess method. Severity of neurologic impairment and clinical recovery was assessed using the Japanese Orthopedic Association score and Hirabayashi’s method. [NOx] in CCM and LCS, but not CDH and LDH groups, was significantly higher than that in controls, and correlated with postoperative recovery rates, but not with preoperative neurologic severity. [NOx] significantly correlated with neurologic recovery following surgery for CCM and LCS.