Peak Wavelength Value Research Articles

Influence of Peak Wavelengths on Properties of Mixed-LED White-Light Sources

The purpose of this investigation is to quantify the influence of the peak wavelength shifts in commercially available LEDs on the characteristics of the mixed-LED white-light sources. For this purpose, a tetrachromatic spectrum was optimized and then subjected to deviations in the peak wavelengths. A total of 882 combinations of peak wavelength values were evaluated, and the results are reported in terms of correlated colour temperature, colour-rendering properties, and radiant luminous efficacy. The results show that there can be significant changes in the characteristics of the source under these conditions. Such changes are highly likely to present problems when dealing with applications where an effective and accurate white-light source is important.

Identifying Modulators of Protein−Protein Interactions Using Photonic Crystal Biosensors

Inhibitors and activators of protein-protein interactions are valuable as biological probes and medicinal agents but are often difficult to identify. Herein we describe a high-throughput assay, based upon photonic crystal (PC) biosensors, for the identification of modulators of protein-protein interactions. Through the use of a d-biotin-tris-NTA (BTN) hybrid compound, any His6-tagged protein can be immobilized on the surface of a PC biosensor. Binding of the bound protein to its cognate partner is detected via a shift in the peak wavelength value. We demonstrate this assay with three protein-protein pairs (caspase-9-XIAP, caspase-7-XIAP, FKBP12-FRB) and their small molecule modulators.

Compact wavelength detection system incorporating a guided-mode resonance filter

The authors demonstrate a compact system for the detection of the peak wavelength value emitted by a light source. The system is composed of only two components, a graded-wavelength guided-mode resonance filter placed before a charge-coupled device sensor array. The filter provides a spatially resolved transmission minimum, the position of which is controlled by the wavelength of the incoming light. The sensor array collects the spatially resolved transmitted intensity and the wavelength is determined by recording the position of the transmission minimum along its length. Using this technique, wavelength changes as small as 0.011nm can be detected.

Silicon-Crystal Determination of the Absolute Scale of X-Ray Wavelengths

In a recent evaluation of the atomic constants, the value of Avogadro's number is $N=6.02252\ifmmode\times\else\texttimes\fi{}{10}^{23}{(\mathrm{g}\mathrm{mole})}^{\ensuremath{-}1}\ifmmode\pm\else\textpm\fi{}11$ ppm (probable error). Measurements on the atomic weight of silicon give $A=28.0857\ifmmode\pm\else\textpm\fi{}10$ ppm. Precision measurements of the density of silicon combined with the above values in the Bragg equation $a={(\frac{\mathrm{fA}}{\ensuremath{\rho}N})}^{\frac{1}{3}}$ result in an absolute grating constant of high precision. X-ray diffraction measurements with the same crystal yield the grating constant in x units; thus the conversion factor from x units to cm can be evaluated. X-ray and density measurements have been made on 17 selected silicon crystals from four different sources. The statistical error in the measurement of the densities of the 17 crystals was \ifmmode\pm\else\textpm\fi{}0.4 ppm. To obtain the absolute density error, a 3 ppm probable error in the density of water must be added, giving a total error of \ifmmode\pm\else\textpm\fi{}3.1 ppm. The measured densities of two of the 17 crystals differed from the average by more than 3 $\ensuremath{\sigma}$, probably indicating a difference in the density of the crystals. The x-ray diffraction measurements were made with a double-crystal spectrometer using the copper $K{\ensuremath{\alpha}}_{1}$ and $K{\ensuremath{\alpha}}_{2}$ lines. The wavelengths in angstroms were evaluated from the Bragg law for each of the 17 crystals and for the ${\ensuremath{\alpha}}_{1}$ and ${\ensuremath{\alpha}}_{2}$ lines. The average wavelengths were Cu $K{\ensuremath{\alpha}}_{1}=1.540563 \AA{}\ifmmode\pm\else\textpm\fi{}5$ ppm, and Cu $K{\ensuremath{\alpha}}_{2}=1.544390 \AA{}\ifmmode\pm\else\textpm\fi{}5$ ppm. Taking the peak wavelength values of 1537.400 xu\ifmmode\pm\else\textpm\fi{}1 ppm for the Cu $K{\ensuremath{\alpha}}_{1}$ and 1541.219 xu\ifmmode\pm\else\textpm\fi{}6.5 ppm for the Cu $K{\ensuremath{\alpha}}_{2}$ lines yields a wavelength conversion factor from angstrom to thousand x units of $\ensuremath{\Lambda}=1.002057 \AA{}/\mathrm{kxu}\ifmmode\pm\else\textpm\fi{}5$ ppm. Recalculation of the best measurements in the literature with current values of the atomic weights gave values which agree with the present work within probable errors. Plane-ruled-grating measurements of x-ray wavelengths yield a value of $\ensuremath{\Lambda}=1.00203\ifmmode\pm\else\textpm\fi{}30$ ppm, which is lower than the above values, but the probable errors overlap.