Large-area, wide-angle, spectrally selective plasmonic absorber

A simple metamaterial-based wide-angle plasmonic absorber is introduced, fabricated, and experimentally characterized using angle-resolved infrared spectroscopy. The metamaterials are prepared by nano-imprint lithography, an attractive low-cost technology for making large-area samples. The matching of the metamaterial's impedance to that of vacuum is responsible for the observed spectrally selective "perfect" absorption of infrared light. The impedance is theoretically calculated in the single-resonance approximation, and the responsible resonance is identified as a short-range surface plasmon. The spectral position of the absorption peak (which is as high as 95%) is experimentally shown to be controlled by the metamaterial's dimensions. The persistence of "perfect" absorption with variable metamaterial parameters is theoretically explained. The wide-angle nature of the absorber can be utilized for sub-diffraction-scale infrared pixels exhibiting spectrally selective absorption/emissivity.Comment: 7 pages, 6 figures, submitted to Phys. Rev.

Probing Kinetic Mechanisms of Protein Function and Folding with Time-Resolved Natural and Magnetic Chiroptical Spectroscopies

Recent and ongoing developments in time-resolved spectroscopy have made it possible to monitor circular dichroism, magnetic circular dichroism, optical rotatory dispersion, and magnetic optical rotatory dispersion with nanosecond time resolution. These techniques have been applied to determine structural changes associated with the function of several proteins as well as to determine the nature of early events in protein folding. These studies have required new approaches in triggering protein reactions as well as the development of time-resolved techniques for polarization spectroscopies with sufficient time resolution and sensitivity to probe protein structural changes

The Melt Heat Treatment and the Structural Changes in ZhS6U and Inconel 718

One of the most curious phenomena observed in metal melts is the temperature-induced liquid-liquid structural changes. As a result of the thermal treatment lead to LLT, a more equilibrium and micro-uniform melt consisting of atomic associations is formed. In nickel alloy melts, the changes that have occurred are irreversible and have a significant effect on the formation of the final structure and the mechanical properties of the metal in the solid state after its crystallization. In addition, they are the starting point for the scientific substantiation of new technological modes of smelting and heat treatment of alloys, which further improve their operational properties, as well as reduce metallurgical defects and production waste, and rational use of expensive ligands. All this in general will lead to a significant increase in the performance of melts and metal products. Our work is devoted to the experimental confirmation of the LLT transition in two common nickel-based alloys by a non-invasive electromagnetic method. © Published under licence by IOP Publishing Ltd

The forward problem of spectral reflection prediction: Mutual match between framework selection and the training set volume

Novel technology of the color reproduction is closely related to a variety of color prediction techniques. Along with the deterministic models, those based on the use of artificial neural networks have recently begun to appear. An important problem in the application of a neural network approach is the choice of the training set and network training algorithms. In our work, we describe the results of a computational experiment where various configurations of the artificial neural networks along the different volumes of training subsamples were simultaneously determined providing a satisfactory accuracy of the spectral reflection prediction. The results show that each subsample might be mapped to a particular network configuration. © 2020 American Institute of Physics Inc.. All rights reserved

Variation of quadrupole splitting in modified oxyhemoglobin: A Mössbauer effect study

Human adult hemoglobin modified by both pyridoxal-5′-phosphate and glutaraldehyde in the oxy-form was studied by Mössbauer spectroscopy. Mössbauer spectra were measured at 87 and 295 K (hemoglobin in lyophilized form) and at 87 K (hemoglobin in frozen solution). The values of the quadrupole splitting for modified oxyhemoglobin were found to be lower then those of oxyhemoglobin without modifications in lyophilized form and frozen solution, respectively. The Mössbauer spectra of modified oxyhemoglobin were also analyzed in terms of the heme iron inequivalence in α- and β-subunits of the tetramer. Differences of the tendencies of temperature dependencies of quadrupole splitting for modified and non-modified oxyhemoglobin in lyophilized form were shown. Key words: Hemoglobin; Mössbauer Spectroscopy; Quadrupole Spitting.This work was supported in part by the Russian Foundation for Basic Research (grant # 97-04-49482)

The inverse problem of spectral reflection prediction: Problems of framework selection

Digital image processing requires substantial computations for characterization. It is since the reliable color reproduction can be achieved by establishing the correspondence between the spectral reflectance of the printed surface and the amounts of deposited inks. The processing is implemented by using different mathematical models. Most of the color prediction models engage some mathematical techniques to predict spectral reflectance for a mixture of colorants that are characterized by absorption and scattering during the light propagation. However, few attempts were made to make a model for prediction the colorants values based on an observing spectrum. This work is devoted to application of artificial neural network approach for solving the inverse problem of spectral reflection prediction. This task has been considered unsolvable as it involves solving a system of the linear differential equations, in which the number of unknowns exceeds the number of equations. Our attempt is based on the assumption that the prediction of the initial colorants from spectral data is possible by analogy with the work of the color perception system in humans. The aim of our study is to offer an approach to the framework selection. The model is built in Matlab and shows satisfactory prediction accuracy. © 2020 American Institute of Physics Inc.. All rights reserved

Determining the ideal initial printing colorants in electrophotography by the discrete gradation trajectories

The accuracy and repeatability of the color reproduction in print is determined by the fine-tuning of the tone reproduction curves of the basic printing colorants (most often this is CMYK). However, the diversity of manufacturers of printing equipment and dyes introduces an element of significant uncertainty about color uniformity. In addition, the traditional approach does not take into account the effect of hue change when applying the original dyes, as well as the nonlinearity of the hue rise in high- and low-density areas. Determining the color of base colorants that produces the most uniform tone change is an important engineering challenge. Previously, there was no scientific basis for such calculations. We recently proposed an alternative color correction model based on gradation trajectories as an analogue of gradation curves in the CIE Lab space. We have also described the extension of the approach to double color overlay (gradation surfaces) and its analytical and discrete implications. The trajectories are the geodetic lines on gradation surfaces. In this paper, we propose using the gradation trajectories to determine “ideal” or “true” initial printing dyes for electrophotography. To simplify calculations, natural color discretization in digital printing is used. © 2022 John Wiley & Sons, Ltd.Wake Forest University, WFUSupport for this research was provided by the Babcock Graduate School of Management, Wake Forest University; Rutgers Business School – Newark and New Brunswick, Rutgers University; and the Jones Graduate School of Management, Rice University. Helpful comments on earlier versions of this chapter were provided by Jack Brittain, Margaret Duval, Reuben McDaniel, Tim Ruefli, John Slocum, Kathie Sutcliffe, and Doug Wholey

Mathematics and practice of color space invariants by the example of determining the gray balance for a digital printing system

In modern printing, a large number of tasks are associated with the mutual transformation of color spaces. In particular, the most common pair of hardware-dependent color spaces is RGB and CMYK, the mutual transformation of colors in which is ambiguous, which creates significant problems in color reproduction. To solve this problem, we propose using color space invariants — gradation trajectories and gradation surfaces, which are analogs of gradation curves for initial col-orants and their binary overlays, constructed in the absolute color space of the CIE Lab. Invariants are introduced on the basis of the mathematical apparatus of the differential geometry of spatial curves and surfaces. Practical application of color space invariants involves certain difficulties associated with their complex analytical description; moreover, for most practical problems, the high accuracy of the model is redundant. For the practical application of invariants, we propose a simpler approach using natural color sampling in digital printing systems. As an example, the procedure for determining the gray balance for an electrophotographic printing press is given. © 2020, Institution of Russian Academy of Sciences. All rights reserved