Yellow Chromophore Research Articles

Blue-Light Filtering Monofocal Intraocular Lenses: A Study on Optical Function and Tolerance to Misalignment.

To investigate the optical performance and tolerance to misalignment of blue-light filtering monofocal intraocular lenses (IOLs). The optical properties of two monofocal IOLs featuring yellow chromophores, CT Lucia 621 PY (Carl Zeiss Meditec AG) and Clareon CNA0T0 (Alcon Laboratories, Inc), were assessed in monochromatic and polychromatic light while introducing spherical aberration (SA). Optical quality metrics derived from the modulation transfer function were assessed after optimal IOL centration at 3- and 4.5-mm pupils. In addition, each IOL's tolerance to misalignment was examined by inducing up to 1 mm of decentration and the effect of tilting it by 5 degrees at 3 mm. The IOLs' resolution and contrast, while tested using a 3-mm aperture and an SA-neutral corneal model, indicated the CT Lucia 621 PY had a slightly higher modulation transfer function (MTF) at 50 lp/mm than the CNA0T0 under monochromatic conditions (0.77 vs 0.69). On introducing SA with (0.49 vs 0.40) and without (0.75 vs. 0.70) chromatic aberration, the CT Lucia 621 PY maintained its minimally better performance. When assessed with a 4.5-mm aperture in monochromatic light, the CT Lucia 621 PY displayed improved MTF with aberration-free cornea (0.71 vs 0.40) but performed worse after introducing SA (0.44 vs 0.62). However, both lenses achieved comparable MTF values under spherical and chromatic aberrations (0.28 vs 0.27). The IOL misalignment test revealed a better tolerance to tilt and decentration of the CT Lucia 621 PY across all conditions. The CT Lucia 621 PY and CNA0T0 showed similar optical quality in different situations, with equal simulated distance visual acuity for both models. However, the CT Lucia 621 PY's aspheric design offers an advantage when dealing with often imperfect physiological conditions, displaying a more robust performance under tilt and decentration. [J Refract Surg. 2024;40(2):e79-e88.].

Solar cell UV‐induced degradation or module discolouration: Between the devil and the deep yellow sea

AbstractFor decades, photovoltaic (PV) module yellowing caused by UV exposure has been observed on solar arrays in operation. More than an aesthetic inconvenience, this phenomenon can severely impair module performance and promote other degradation mechanisms by undermining the photoprotection provided by encapsulation. To understand how this reaction may affect current encapsulation materials, silicon heterojunction (SHJ) monocell modules with either UV‐cut or UV‐transparent commercial encapsulants were aged under UV irradiation and examined by visual inspection, fluorescence imaging and flash tests. Despite the photoprotection they provide, only the encapsulants that were stabilised by UV absorbers underwent discolouration. On the one hand, UV absorber photodegradation is responsible for the formation of yellow chromophores that affect light transmission to the cell, which could cause net decrease in the photogenerated current high as 4% after 4200 h of accelerated UV ageing. On the other hand, UV‐induced degradation of SHJ solar cells only accounts for a lower photogenerated current loss (3%), in contrast with previous observations in the literature. According to the behaviour of the current encapsulation formulation, the stability of UV absorbing additives has to be improved to ensure the durability of the device over 30 years.

Sleep Deprivation Increases Facial Skin Yellowness.

Sleep shortage is a major concern in modern life and induces various psycho-physical disorders, including skin problems. In cosmeceutics, females are aware that sleep deprivation worsens their facial skin tone. Here, we measured the effects of sleep deprivation on facial skin yellowness and examined yellow chromophores, such as bilirubin and carotenoids, in blood serum as potential causes of yellowness. Total sleep deprivation (0 h sleep overnight, N = 28) and repeated partial sleep deprivation (4 h sleep for 5 consecutive days, N = 10) induced significant increases in facial skin yellowness. The higher yellowness was sustained even after both sleep deprivation types stopped. However, circulating levels of yellow chromophores were unchanged in the total sleep deprivation study. Neither circulating interleukin-6 nor urinary biopyrrin levels were affected by total sleep deprivation, suggesting that apparent oxidative stress in the body was not detected in the present total deprivation protocol. Facial redness was affected by neither total nor repeated partial sleep deprivation. Therefore, blood circulation may play a limited role in elevated yellowness. In conclusion, facial skin yellowness was indeed increased by sleep deprivation in our clinical studies. Local in situ skin-derived factors, rather than systemic chromophore change, may contribute to the sleep deprivation-induced elevation of facial skin yellowness.

Eco-friendly dual-chromophore functionalized polyvinylamine derivatives for clean and sustainable coloration of cotton fabric

To solve the challenges of dyeing wastewater pollution and the shortage of reactive green dyes with a single structure, the development of recoverable and recyclable green dye for cotton is urgent and crucial. In this work, a series of novel eco-friendly dual-chromophore functionalized polyvinylamine derivatives (GCPDs) were prepared by grafting yellow and blue chromophores onto polyvinylamine. The grafted polyvinylamine was used as pH-sensitive macromolecular colorants for clean and sustainable coloration of cotton fabric. The pH sensitivity, zeta potential, and dissociation behavior of the GCPDs were studied. The results revealed that GCPDs were sensible to pH, with an isoelectric point ranging from 8.5 to 10.0. When the pH of their solution was below 10, they formed aggregates due to strong electrostatic interactions. Compared with ordinary polyampholytes, the aggregation of GCPDs still occurred when the pH value of their solution deviated from the isoelectric point due to the presence of aromatic rings in their structure. The inner part of the cotton yarns colored with GCPDs was fixed with green color, indicating that GCPDs can be uniformly distributed in cotton fabric. Compared with conventional single-structure reactive green dyes, the color shade of the cotton dyed with GCPDs can be controlled by varying the types and molar ratios of the blue and yellow chromophores in their structure. CIELab values showed that a* value of the dyed cotton ranged from −26.065 to −12.548, while b* value shifted from 2.092 to 20.178. The fixation efficiency of the GCPDs on cotton was greater than 97% when a cross-linking agent was used. GCPDs can be recovered from dying residue, with a recovery rate of >98%. The cotton dyed with GCPDs exhibited rubbing and wash fastness grades of 3–4 and 5, respectively. The dyeing properties of recycled GCPDs were identical to those of the original GCPDs. Therefore, this study provides insight into the development of recyclable and reusable dyes for a clean and sustainable coloration of cotton fabric.

A Potential Role of Keratinocyte-Derived Bilirubin in Human Skin Yellowness and Its Amelioration by Sucrose Laurate/Dilaurate.

Sallow and/or dull skin appearance is greatly attributable to the yellow components of skin tone. Bilirubin is a yellow chromophore known to be made in the liver and/or spleen and is transported throughout the body via the blood stream. Recent publications suggest bilirubin may be synthesized in other cells/organs, including the skin. We found human keratinocytes express the transcripts involved in bilirubin biosynthesis. In parallel, we also found human keratinocytes could indeed synthesize bilirubin in monolayer keratinocytes and in a 3D human skin-equivalent model. The synthesized amount was substantial enough to contribute to skin yellowness. In addition, oxidative stress enhanced bilirubin production. Using UnaG, a protein that forms a fluorescent species upon binding to bilirubin, we also visualized the intracellular expression of bilirubin in keratinocytes. Finally, we screened a compound library and discovered that the sucrose laurate/dilaurate (SDL) combination significantly reduced bilirubin levels, as well as bilirubin-mediated yellowness. In conclusion, bilirubin is indeed synthesized in epidermal keratinocytes and can be upregulated by oxidative stress, which could contribute to chronic or transient yellow skin tone appearance. Application of SDL diminishes bilirubin generation and may be a potential solution to mitigate yellowish and/or dull skin appearance.

The Influence of Intraocular Lenses (IOLs) on the Properties of Filters Protecting Human Eyes against Optical Radiation in the Work Environment.

Under the specific illumination conditions of many workplaces, e.g., in the metallurgical industry, decreased lighting may impair workers’ vision and, as a result, their productivity. Spectrophotometric tests of two types of protective optical filters (welding filters and infrared protection filters), two types of intraocular lenses (IOLs with and without yellow chromophore), and filter-IOL systems were carried out. In spectrophotometric studies, the spectral characteristics of transmission and the coefficients for the assessment of light transmission were determined. This study explores the relationship between the eye protection levels offered by filters and the use of intraocular lenses (IOLs), and especially those containing a yellow chromophore which may lower the luminous transmittance of protective filters. In our previous works, we studied a large number of optical protective filters and many factors influencing their performance. A review of the literature has shown the absence of prior research on the subject. For this purpose, transmittance reduction factors were defined for the evaluation of the filter-IOL system. The spectral characteristics of luminous transmittance for the tested IOLs indicate a significant decrease of transmittance for those with yellow chromophore within the range up to approx. 475 nm, as compared to IOLs without chromophore. The main objective of this study was to determine whether people with IOLs need different protective filters against harmful optical radiation as well as whether IOLs may change the required category of protective filters. The key finding is that while the use of IOLs in conjunction with protective filters does change the light transmission coefficient, it does not affect the filter protection levels. The transmittance reduction factors were similar (0.95 to 0.99 relative units) for all filter-IOL systems irrespective of the presence or absence of yellow chromophore. It must be said clearly that, in reference to the requirements specified in the standards, IOLs did not affect the filter protection levels. This means that the quality of vision did not change significantly when using the analyzed filters and IOLs.

Spectroscopic and Crystal-Chemical Features of Sodalite-Group Minerals from Gem Lazurite Deposits

Five samples of differently colored sodalite-group minerals from gem lazurite deposits were studied by means of electron microprobe and wet chemical analyses, infrared, Raman, electron spin resonance (ESR) and UV-Visible spectroscopy, and X-ray diffraction. Various extra-framework components (SO42−, S2− and Cl− anions, S3•−, S2•− and SO3•− radical anions, H2O, CO2, COS, cis- as well as trans- or gauche-S4 neutral molecules have been identified. It is shown that S3•− and S4 are the main blue and purple chromophores, respectively, whereas the S2•− yellow chromophore and SO3•− blue chromophore play a subordinate role. X-ray diffraction patterns of all samples of sodalite-group minerals from lazurite deposits studied in this work contain superstructure reflections which indicate different kinds of incommensurate modulation of the structures.

Geometric and electronic structure probed along the isomerisation coordinate of a photoactive yellow protein chromophore

Understanding the connection between the motion of the nuclei in a molecule and the rearrangement of its electrons lies at the heart of chemistry. While many experimental methods have been developed to probe either the electronic or the nuclear structure on the timescale of atomic motion, very few have been able to capture both these changes in concert. Here, we use time-resolved photoelectron imaging to probe the isomerisation coordinate on the excited state of an isolated model chromophore anion of the photoactive yellow protein. By probing both the electronic structure changes as well as nuclear dynamics, we are able to uniquely measure isomerisation about a specific bond. Our results demonstrate that the photoelectron signal dispersed in time, energy and angle combined with calculations can track the evolution of both electronic and geometric structure along the adiabatic state, which in turn defines that chemical transformation.

An XPS study into sulphur speciation in blue and green ultramarine

A number of ultramarine paint samples were analysed by Raman spectroscopy and X-ray photoelectron spectroscopy to determine the binding energies of the S3.− (blue) and S2.− (yellow) radical anions responsible for the pigment colour. The two sulphur radicals (chromophores) have well assigned Raman signals, however, no previous XPS study has been able to observe both radicals in natural or synthesised blue ultramarine samples and assign binding energies. This study focused on the analysis of synthetic ultramarine samples, which have a higher chromophore concentration than natural pigments, and on the comparison of blue and green shades, as green pigments have a higher quantity of the yellow chromophore. XPS spectra from six blue and three green paints were processed and found to contain sulphide, sulphite, sulphate and two unassigned signals at 162.9 and 163.8 eV. The ratio of these two signals varied between blue and green samples. Raman spectra of the samples were measured and the ratio of the blue versus yellow signals at 549 cm−1 and 580 cm−1 calculated. Comparison of the Raman and XPS data sets found good agreement between signal ratios when the 162.9 eV XPS signal was assigned to the yellow and the 163.8 eV signal was assigned to the blue chromophore.

Thermal yellowing and photobleaching of automotive topcoats

Thermal yellowing and photobleaching are common problems that are seen to some extent in all automotive topcoat systems today. These effects can cause difficulties in the matching of light colors in the assembly plant and then later upon delivery to the customer. Current literature offers no clear mechanism for the thermal yellowing and photobleaching. Based on observed formulation dependencies, a mechanism is proposed based on oxidation of amine compounds. We constructed a model in vitro system using a hydroperoxide to thermally oxidize amines in solution. In this system, a series of amines were tested and both yellowing and photobleaching were reproduced. Loss of basicity confirmed that amine oxidation occurred under these conditions. Both the location of the UV absorption peak and strong amine structure dependence indicate nitrone formation as the yellow chromophore.

Associated depression in pseudophakic patients with intraocular lens with and without chromophore.

BackgroundWith aging, the crystalline lens turns yellowish, which increases the absorption of wavelengths in the blue electromagnetic spectrum, reducing their photoreception in the retina. Since these wavelengths are the main stimulus in the regulation of the circadian rhythm, progressive reduction in their transmission is associated with chronic sleep disturbances and depression in elderly patients. Cataract extraction improves circadian photoreception at any age. However, lenses that block blue waves have 27% to 38% less melatonin suppression than lenses that block only ultraviolet (UV) rays.PurposeTo assess the depression symptoms in subjects who have had bilateral phacoemul-sification and intraocular lens (IOL) implants, one group with yellow chromophore IOLs and the other group with transparent IOLs were compared.SettingAssociation to Prevent Blindness in Mexico (APEC), Hospital “Dr Luis Sánchez Bulnes”.DesignThis was an observational, cross-sectional, and single-center study.Materials and methodsTwenty-six subjects between 60 and 80 years of age, with a history of bilateral phacoemulsification and placement of the same type of IOL in both eyes from 4 to 12 months prior to the study, who attended the follow-up visits and agreed to participate in this study, and provided signed informed consent were included in the study. They were asked to answer the short version of the 15-item Geriatric Depression Scale.ResultsThe average age of the study participants was 72.5±5.94 years. The group without chromophore included 46.1% (n=12) of the patients and the group with chromophore included 53.9% (n=14) of the patients (P=0.088).ConclusionIn the group of patients with IOLs that block the passage of blue light, the depression rate was 21.4%, a rate similar to that observed in the elderly population, whereas no patients in the group with transparent IOLs had depression.

Light transmission through intraocular lenses with or without yellow chromophore (blue light filter) and its potential influence on functional vision in everyday environmental conditions

In this research the factors used to evaluate the light transmission through two types of acrylic hydrophobic intraocular lenses, one that contained yellow chromophore that blocks blue light transmission and the other which did not contain that filter, were defined according to various light condition, e.g., daylight and at night. The potential influence of light transmission trough intraocular lenses with or without yellow chromophore on functional vision in everyday environmental conditions was analysed.

신규 Phthaloperinone 색소의 합성과 특성에 대한 연구

New series of phthaloperinone dyes were synthesized by the condensation reaction between tetrachloro-phthalic anhydride, 2,3-naphthalene dicarboxylic anhydride and o-phenylenediamine, 1,8-diaminonaphthalene, 1,2-diaminoanthraquinone. These dyes absorb at around 370-490nm. It was found that introduction of naphthalene and anthraquinone moiety on the perinone system produces a large bathochromic shift of 100nm. The synthesized dye 7 containing anthraquinone moiety in perinone chromophoric system exhibited superior heat stability and bright color as yellow chromophore. New dye 7 have been investigated in terms of interacting with volatile organic compound(VOC) <TEX>$EtNH_2$</TEX>. The sensing behaviour of the dye 7 toward <TEX>$EtNH_2$</TEX> was studied by UV-vis absorption spectroscopy. Sensing mechanism of dye 7 to <TEX>$EtNH_2$</TEX> was supported by theoretical calculations based on DFT method.

The influence of the exposure conditions on the chemical and physical changes of polyester–urethane coatings during photodegradation

The influence of the conditions of artificial degradation experiments on the photodegradation process of polyester–urethane clearcoats has been studied by comparing three types of exposure experiments with different conditions regarding the spectral power distribution (SPD), the exposure atmosphere (aerobic and anaerobic) and the presence of water. The presence of short wavelengths (λ < 295 nm) in the SPD largely influences the depth-inhomogeneity of degradation with respect to the optical properties and the chemical composition of the coating. The availability of oxygen in the exposure atmosphere determines the degradation pathway that is followed, such as to what extent the photo-oxidative breakage of urethane bonds or the formation of yellow chromophores due to aromatic crosslinking reactions occurs. Indentations at the surfaces of virgin and degraded coatings showed an increase in Young's modulus and hardness when degraded under aerobic conditions, while degradation under anaerobic conditions did not lead to significant changes. The presence of water is responsible for increasing the surface roughness of the coating during degradation, which directly influences the coating's gloss retention. Several time-independent correlations between the changes in chemical, optical and mechanical properties of coatings resulting from different exposure experiments have been established.

Yellowing and bleaching of grey hair caused by photo and thermal degradation

Yellowing is an undesirable phenomenon that is common in people with white and grey hair. Because white hair has no melanin, the pigment responsible for hair colour, the effects of photodegradation are more visible in this type of hair. The origin of yellowing and its relation to photodegradation processes are not properly established, and many questions remain open in this field. In this work, the photodegradation of grey hair was investigated as a function of the wavelength of incident radiation, and its ultrastructure was determined, always comparing the results obtained for the white and black fibres present in grey hair with the results of white wool.The results presented herein indicate that the photobehaviour of grey hair irradiated with a mercury lamp or with solar radiation is dependent on the wavelength range of the incident radiation and on the initial shade of yellow in the sample. Two types of grey hair were used: (1) blended grey hair (more yellow) and (2) grey hair from a single-donor (less yellow). After exposure to a full-spectrum mercury lamp for 200h, the blended white hair turned less yellow (the yellow–blue difference, Db* becomes negative, Db*=−6), whereas the white hair from the single-donor turned slightly yellower (Db*=2). In contrast, VIS+IR irradiation resulted in bleaching in both types of hair, whereas a thermal treatment (at 81°C) caused yellowing of both types of hair, resulting in a Db*=3 for blended white hair and Db*=9 for single-donor hair. The identity of the yellow chromophores was investigated by UV–Vis spectroscopy. The results obtained with this technique were contradictory, however, and it was not possible to obtain a simple correlation between the sample shade of yellow and the absorption spectra. In addition, the results are discussed in terms of the morphology differences between the pigmented and non-pigmented parts of grey hair, the yellowing and bleaching effects of grey hair, and the occurrence of dark-follow reactions.

Elimination of Redundant and Stop Codons during the Chemical Synthesis of Degenerate Oligonucleotides. Combinatorial Testing on the Chromophore Region of the Red Fluorescent Protein mKate

Although some strategies have been reported for the elimination of stop and redundant codons during the chemical synthesis of degenerate oligonucleotides, incorporating an expensive cocktail of 20 trimer-phosphoramidites is currently a commonly employed and straightforward approach. As an alternative option, we describe here a cheaper strategy based on standard monomer-phosphoramidites and a simplified resin-splitting procedure. The accurate division of the resin, containing the growing oligonucleotide, into four columns represents the key step in this approach. The synthesis of the degenerate codon NDT in column 1, loaded with 60% of the resin, produces 12 codons, while a degenerate codon VMA in column 2, loaded with 30% of the resin, produces 6 codons. Codons ATG and TGG, independently synthesized in columns 3 and 4, respectively, and loaded with 5% each, completes the 20 different codons. The experimental frequency of each mutant codon in the library was assessed by randomizing 12 contiguous codons that encode for amino acids located in the chromophore region of the enhanced red fluorescent protein mKate-S158A. Furthermore, randomization of three contiguous codons that encode for the amino acids Phe62, Met63, and Tyr64, which are equivalent to Phe64, Ser65, and Tyr66 in GFP, gave rise to some red and golden yellow fluorescent mutants displaying interesting phenotypes and spectroscopic properties. The absorption and emission spectra of two of these mutants also suggested that the complete maturation of the red and golden yellow chromophores in mKate proceeds via the formation of a green-type chromophore and a cyan-type chromophore, respectively.

Ultraviolet-resonance femtosecond stimulated Raman study of the initial events in photoreceptor chromophore

Newly-developed ultraviolet-resonance femtosecond stimulated-Raman spectroscopy was utilized to study the initial structural evolution of photoactive yellow protein chromophore in solution. The obtained spectra changed drastically within 1 ps, demonstrating rapid in-plane deformations of the chromophore.

Diffuse reflectance spectroscopy of fibrous proteins

UV-visible diffuse reflectance (DR) spectra of the fibrous proteins wool and feather keratin, silk fibroin and bovine skin collagen are presented. Natural wool contains much higher levels of visible chromophores across the whole visible range (700-400nm) than the other proteins and only those above 450nm are effectively removed by bleaching. Both oxidative and reductive bleaching are inefficient for removing yellow chromophores (450-400nm absorbers) from wool. The DR spectra of the four UV-absorbing amino acids tryptophan, tyrosine, cystine and phenylalanine were recorded as finely ground powders. In contrast to their UV-visible spectra in aqueous solution where tryptophan and tyrosine are the major UV absorbing species, surprisingly the disulphide chromophore of solid cystine has the strongest UV absorbance measured using the DR remission function F(R)(∞). The DR spectra of unpigmented feather and wool keratin appear to be dominated by cystine absorption near 290nm, whereas silk fibroin appears similar to tyrosine. Because cystine has a flat reflectance spectrum in the visible region from 700 to 400nm and the powder therefore appears white, cystine absorption does not contribute to the cream colour of wool despite the high concentration of cystine residues near the cuticle surface. The disulphide absorption of solid L: -cystine in the DR spectrum at 290nm is significantly red shifted by ~40nm relative to its wavelength in solution, whereas homocystine and lipoic acid showed smaller red shifts of 20nm. The large red shift observed for cystine and the large difference in intensity of absorption in its UV-visible and DR spectra may be due to differences in the dihedral angle between the crystalline solid and the solvated molecules in solution.

Facile synthesis and characterization of novel coronene chromophores and their application to LCD color filters

New coronene derivatives, diphenylcoronene tetracarboxdiimide and monophenylbenzoperylene tetracarboxdiimide, were synthesized from N,N′-bis(2,6-diisopropylphenyl)-1,7-dibromoperylene-3,4,9,10-tetracarboxdiimide via a one-step reaction. The suggested synthetic route is the simplest and most economical among the methods to extend the aromatic systems along the short molecular axis of perylene. The synthesized molecules exhibited superior stability and color strength as yellow chromophores. They were characterized by significant hypsochromic shifts of the absorption compared to perylene tetracarboxdiimide and high fluorescence quantum yields.

Formula omitted] radicals in ε-cages of cancrinite and zeolite L: Spectroscopic and magnetic resonance studies

Spectroscopic methods such as UV–Vis, Raman, ESR and electron spin echo were applied for characterization of polysulfide chromophore thermally formed in cancrinite and zeolite L containing ε-cages in their structures. The UV–Vis and Raman spectra indicated predominant contribution of oligosulfides S n (with n = 2–4) in samples prepared at 650 °C from mixtures of medium alkalinity. Estimated number of S 3 - (blue chromophore) was two orders of magnitude lower (∼3 × 10 16 radicals/g) than in pigments with sodalite or zeolite A structures where it is located in β-cages. The number of S 2 - (yellow chromophore) was even smaller. The continuous ESR and pulse ESR measurements at room temperature and at 10 K indicated that most (>90%) of S 3 - radicals are localized inside ε-cages and remaining ones exhibit free reorientations. The localization in the ε-cages well explains a shift of ESR g-factors compared to that observed for radicals localized in β-cages as well as different dynamical behavior of radical molecules i.e. reorientations around c-axis instead of spatial reorientations existing in β-cages at room temperature.