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Keywords = wavelength blueshift

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16 pages, 1420 KiB  
Article
Light-Driven Quantum Dot Dialogues: Oscillatory Photoluminescence in Langmuir–Blodgett Films
by Tefera Entele Tesema
Nanomaterials 2025, 15(14), 1113; https://doi.org/10.3390/nano15141113 - 18 Jul 2025
Viewed by 315
Abstract
This study explores the optical properties of a close-packed monolayer composed of core/shell-alloyed CdSeS/ZnS quantum dots (QDs) of two different sizes and compositions. The monolayers were self-assembled in a stacked configuration at the water/air interface using Langmuir–Blodgett (LB) techniques. Under continuous 532 nm [...] Read more.
This study explores the optical properties of a close-packed monolayer composed of core/shell-alloyed CdSeS/ZnS quantum dots (QDs) of two different sizes and compositions. The monolayers were self-assembled in a stacked configuration at the water/air interface using Langmuir–Blodgett (LB) techniques. Under continuous 532 nm laser illumination on the red absorption edge of the blue-emitting smaller QDs (QD450), the red-emitting larger QDs (QD645) exhibited oscillatory temporal dynamics in their photoluminescence (PL), characterized by a pronounced blueshift in the emission peak wavelength and an abrupt decrease in peak intensity. Conversely, excitation by a 405 nm laser on the blue absorption edge induced a drastic redshift in the emission wavelength over time. These significant shifts in emission spectra are attributed to photon- and anisotropic-strain-assisted interlayer atom transfer. The findings provide new insights into strain-driven atomic rearrangements and their impact on the photophysical behavior of QD systems. Full article
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10 pages, 1703 KiB  
Article
The Performance Degradation of Red, Green, and Blue Micro-LEDs Under High-Temperature Electrical Stress
by Changdong Tong, Yu Liu, Quan Deng, Li Pan, Guolong Chen, Yijun Lu, Tingzhu Wu, Zhong Chen and Weijie Guo
Crystals 2025, 15(7), 604; https://doi.org/10.3390/cryst15070604 - 27 Jun 2025
Viewed by 338
Abstract
In this work, the degradation in luminous characteristics of red, green, and blue (RGB) micro-LEDs (10 µm × 10 µm) under electrical stress at 360 K has been investigated. After 280 h of aging, the AlGaInP-based red micro-LEDs exhibit a 31.7% reduction in [...] Read more.
In this work, the degradation in luminous characteristics of red, green, and blue (RGB) micro-LEDs (10 µm × 10 µm) under electrical stress at 360 K has been investigated. After 280 h of aging, the AlGaInP-based red micro-LEDs exhibit a 31.7% reduction in maximum external quantum efficiency, which is significantly greater than the reductions observed in InGaN-based green and blue micro-LEDs. Specifically, the peak wavelength redshift by 0.6 nm, and blueshift 1.0 nm, and 0.5 nm for RGB micro-LEDs, respectively. The color purity of green and blue micro-LEDs decreases by 3.6% and 0.7%, respectively, resulting in a 7% reduction in color gamut. Full article
(This article belongs to the Special Issue II-VI and III-V Semiconductors for Optoelectronic Devices)
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22 pages, 2988 KiB  
Article
Assessment of pH-Induced Conformational Changes in Whey Protein Isolate–Dextran Conjugate Using Spectral Technology
by Qingyuan Dai, Huiqin Wang, Xiuling Zhu, Polyanna Silveira Hornung, Yuru Zhang, Wenxuan Hu, Anqi Lin, Anyi Yao and Trust Beta
Foods 2025, 14(11), 1952; https://doi.org/10.3390/foods14111952 - 30 May 2025
Viewed by 663
Abstract
The functional properties of proteins are closely related to their structure and conformation. The effects of glycosylation and pH on the structural and conformational changes in whey protein isolate (WPI) were investigated using multispectral technology. More and higher-molecular-weight molecules of WPI–dextran conjugates (WDCs) [...] Read more.
The functional properties of proteins are closely related to their structure and conformation. The effects of glycosylation and pH on the structural and conformational changes in whey protein isolate (WPI) were investigated using multispectral technology. More and higher-molecular-weight molecules of WPI–dextran conjugates (WDCs) with increased degrees of glycosylation (DGs) in SDS-PAGE occurred at the expense of band intensities of α-lactalbumin, β-lactoglobulin, and bovine serum albumin. The higher wavenumber shift in FTIR peaks of WPI after glycosylation in the Amide I, II, and III regions and the decrease in its intensity occurred. The maximum absorption wavelength (λmax) of UV-Vis spectra of WPI before and after glycosylation in the range of 260–290 nm showed no significant difference in a pH range of 2.0–10.0. Moreover, the UV-Vis absorption intensities of WDCs at λmax around 278 nm were highly and positively correlated with their DGs. The λmax and intensities of total intrinsic fluorescence spectra of Tyr and Trp residues in WDCs with an increase in DGs had an obvious redshift and decrease, respectively. Although the intensities of synchronous fluorescence spectra of individual Tyr or Trp residues in WDCs with an increase in DGs also gradually decreased, the λmax of the former and latter had a blueshift and redshift, respectively. UV-Vis absorption and fluorescence spectroscopies indicated that the changes in the λmax and intensity of WPI were closely related to the protonation states of carbonyl groups and free amino groups and the degree of glycosylation. This work may be beneficial for understanding the structural and conformational changes in proteins by measuring the microenvironment around Tyr and/or Trp residues in proteins using UV-Vis absorption and synchronous fluorescence spectroscopies, providing a promising technique for quantitatively monitoring the degree of glycosylation (DG) in a rapid and practical way without any chemical reagents using UV-Vis absorption spectroscopy. Full article
(This article belongs to the Section Food Engineering and Technology)
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38 pages, 1810 KiB  
Article
Symmetric Responses to Diet by Plumage Carotenoids in Violet-Sensitive Piciform–Coraciiform Birds
by Robert Bleiweiss
Diversity 2025, 17(6), 379; https://doi.org/10.3390/d17060379 - 27 May 2025
Viewed by 663
Abstract
Biological studies on symmetry can be expanded to consider red (longer wavelengths) and blue (shorter wavelengths) shifts as antisymmetries (opposite-pattern symmetries), which may arise from similar underlying causes (invariant process symmetries). In this context, classic shift asymmetries of redder plumage in response to [...] Read more.
Biological studies on symmetry can be expanded to consider red (longer wavelengths) and blue (shorter wavelengths) shifts as antisymmetries (opposite-pattern symmetries), which may arise from similar underlying causes (invariant process symmetries). In this context, classic shift asymmetries of redder plumage in response to higher dietary carotenoids appear conceptually incomplete, as potential blue-shifted counterparts were not considered. A latent symmetric response is highlighted by recent evidence showing that the maximum absorbance bands of various colorful plumage pigments are red-shifted in birds with ultraviolet-sensitive (UVS) color vision but blue-shifted in those with violet-sensitive (VS) color vision. Blue-shifted responses to increased dietary carotenoid contents may also be underestimated, as relevant studies have focused on species-rich but uniformly UVS Passerida passerines. This study explored the relationship between pattern–process symmetries and diets of VS Piciformes–Coraciiformes by gauging the responses of their plumage reflectance to a modified diet index (Dietc), where the overall rank carotenoid contents of food items were weight-averaged by three levels of importance in a species’ diet. In the case of both sexes, the main long-wavelength reflectance band for the three carotenoid-based pigment classes defined the same graded series of blue shifts in response to higher Dietc. Yellow showed a strong absolute (negative slope) blue shift, orange showed a weaker absolute blue shift, and red exhibited only a blue shift (flat, non-significant slope) relative to absolute red shifts (positive slope). The secondary shorter-wavelength reflectance band was also unresponsive to Dietc in the VS Piciformes–Coraciiformes (relative blue shift) compared with earlier evidence for it decreasing (absolute red shift) at higher Dietc in UVS species. Results for the intervening minimum reflectance (maximum absorbance) band were intermediate between those for the other reflectance bands. No pigment class monopolized lower or higher Dietc, but red was less variable overall. Phylogenetic independence, sexually similar responses, and specimen preservation reinforced characterizations. A review of avian perceptual studies suggested that VS models discriminate yellows and oranges extremely well, consistent with the importance of the corresponding carotenoids as Dietc indicators. Both UVS and VS species appear to produce putatively more costly and possibly beneficial carotenoid metabolites and/or concentrations in response to higher Dietc, supporting underlying invariant processes in relation to carotenoid limitations and honest signaling despite opposite plumage shifts and their different chemical bases. In symmetry parlance, pigment classes (red) or wavebands (short) that lack responses to Dietc suggest broken pattern and process symmetry. The biology of VS Piciformes–Coraciiformes may favor such exceptions owing to selection for visual resemblance and tuning specializations, although universal constraints on physical and chemical properties of (particularly red) carotenoids may favor certain functional tendencies. Thus, symmetry principles organize carotenoid diversity into a simplified and predictive framework linked to color vision. Full article
(This article belongs to the Collection Feature Papers in Animal Diversity)
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13 pages, 5460 KiB  
Article
Dynamic Plasmonic Coupling in Gold Nanosphere Oligomers: Mechanically Tuned Red and Blue Shifts for SERS/SEF
by István Tóth and Cosmin Farcău
Biosensors 2025, 15(3), 181; https://doi.org/10.3390/bios15030181 - 13 Mar 2025
Viewed by 777
Abstract
Controlling the surface plasmon resonances of metal nanostructures is crucial for advancing numerous high-sensitivity optical (bio)sensing applications. Furthermore, dynamically adjusting these resonances enables real-time tuning of the spectrum of enhanced electromagnetic fields in the near field, thereby regulating the optical interactions between molecules [...] Read more.
Controlling the surface plasmon resonances of metal nanostructures is crucial for advancing numerous high-sensitivity optical (bio)sensing applications. Furthermore, dynamically adjusting these resonances enables real-time tuning of the spectrum of enhanced electromagnetic fields in the near field, thereby regulating the optical interactions between molecules and the metal surface. In this study, we investigate the plasmonic behavior of linear oligomers composed of gold nanospheres using finite-difference time-domain electromagnetic simulations. The extinction spectra of linear arrangements such as dimers, trimers, and quadrumers are obtained for different sphere sizes, interparticle gaps, and polarization of the incident light. In view of (bio)sensing applications based on plasmon-enhanced optical spectroscopy such as surface-enhanced Raman/fluorescence (SERS/SEF), the sensitivity of various coupled plasmon modes to the variation of the interparticle gap is evaluated. The achievement of both red-shifting and blue-shifting plasmon modes offers ways to mechanically control the optical response of the linear oligomers in real-time and design new optical sensing protocols. Based on these findings, both an approach for trapping molecules into SERS hotspots and an approach for dual-mode SERS/SEF using a single excitation wavelength are proposed, contributing to the future development of (bio)sensing protocols. Full article
(This article belongs to the Special Issue Surface-Enhanced Raman Scattering in Biosensing Applications)
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23 pages, 8456 KiB  
Article
Dual pH- and Temperature-Responsive Performance and Cytotoxicity of N-Isopropylacrylamide and Acrylic Acid Functionalized Bimodal Mesoporous Silicas with Core–Shell Structure and Fluorescent Feature for Hela Cell
by Huijie Ge, Xiaoli Wang, Shiyang Bai, Yuhua Bi, Fei Liu, Jihong Sun, Wenliang Fu and Donggang Xu
Pharmaceutics 2025, 17(2), 206; https://doi.org/10.3390/pharmaceutics17020206 - 6 Feb 2025
Viewed by 884
Abstract
Background: Polymer-coated mesoporous silica nanoparticles have attracted immense research interest in stimuli-responsive drug delivery systems due to their drug-releasing ability on demand at specific sites in response to external or internal signals. However, the relationships between the coated-copolymer encapsulation and drug delivery performance [...] Read more.
Background: Polymer-coated mesoporous silica nanoparticles have attracted immense research interest in stimuli-responsive drug delivery systems due to their drug-releasing ability on demand at specific sites in response to external or internal signals. However, the relationships between the coated-copolymer encapsulation and drug delivery performance in the hybrid nanocomposites was rarely reported. Therefore, the main objectives of the present work are to explore the cell uptake, cellular internalization, cytotoxicity, and hemolysis performance of the fluorescent hybrid materials with different polymer-encapsulated amounts. Methods: Using (2-(2-aminoethyl)-6-(dimethylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione)-doped poly[(N-isopropylacrylamide)-co-(acrylic acid)] (PAN) as a shell and bimodal mesoporous silicas (BMMs) as a core, the dual pH- and temperature-responsive mesoporous PAN@M-BMMs with the fluorescent performances were synthesized via a radical polymerization approach. The effects of the PAN-coated thicknesses on their physicochemical properties and structural features were demonstrated via XRD and SAXS patterns, SEM and TEM images, FT-IR spectra, and TG analysis. Their mass fractal (Dm) evolutions were elucidated on the basis of the SAXS patterns and fluorescence spectra. Results: The Dm values increased from 2.74 to 2.87 with an increase of the PAN-coated amount from 17 to 26.5% along with the particle size from 76.1 to 85.6 nm and blue-shifting of their fluorescent emission wavelength from 470 to 444 nm. Meanwhile, the PAN@M-BMMs exhibited a high ibuprofen (IBU) loading capacity (13.8%) and strong dual pH-/temperature-responsive drug-releasing performances (83.1%) at pH 7.4 and 25 °C, as comparison with that (17.9%) at pH 2.0 and 37 °C. The simulated results confirmed that the adsorption energy decreased from −67.18 kJ/mol for pure BMMs to −116.76 kJ/mol for PAN@M-BMMs, indicating the PAN-grafting on the surfaces of the BMMs core was beneficial to improve its IBU-adsorption capacity. Its uptake in the HeLa cell line was performed via microplate readers, confocal microscopy, flow cytometry, and ICP measurement, showing a low cytotoxicity at a concentration up to 100 µg/mL. Specially, P0.2AN@M-BMMs had a superior cellular uptake and fluorescence properties via the time-dependent uptake experiments, and exhibited the highest silicon content via the cellular internalization analysis, as compared to other carriers. Hemolysis tests confirmed the hemolysis rates below 5%. Conclusions: These demonstrations verified that PAN@M-BMMs should be a promising biomedical application prospect. Full article
(This article belongs to the Section Drug Delivery and Controlled Release)
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16 pages, 3849 KiB  
Article
Fabrication of Anthocyanidin-Encapsulated Polyvinyl Alcohol Nanofibrous Membrane for Smart Packaging
by Maryam Aldoghaim, Jabrah Alkorbi, Salhah D. Al-Qahtani and Ghadah M. Al-Senani
Nanomaterials 2024, 14(21), 1701; https://doi.org/10.3390/nano14211701 - 24 Oct 2024
Viewed by 1230
Abstract
Smart colorimetric packaging has been an important method to protect human health from external hazardous agents. However, the currently available colorimetric detectors use synthetic dye probes, which are costly, toxic, difficult to prepare, and non-biodegradable. Herein, an environmentally friendly cellulose nanocrystal (CNC)-supported polyvinyl [...] Read more.
Smart colorimetric packaging has been an important method to protect human health from external hazardous agents. However, the currently available colorimetric detectors use synthetic dye probes, which are costly, toxic, difficult to prepare, and non-biodegradable. Herein, an environmentally friendly cellulose nanocrystal (CNC)-supported polyvinyl alcohol (PVA) nanofibrous membrane was developed for the colorimetric monitoring of food spoilage. Anthocyanidin (ACY) is a naturally occurring spectroscopic probe that was isolated from pomegranate (Punica granatum L.). By encapsulating the anthocyanin probe in electrospun polyvinyl alcohol fibers in the presence of a mordant (M), M/ACY nanoparticles were generated. After exposure to rotten shrimp, an investigation on the colorimetric changes from purple to green for the smart nanofibrous fabric was conducted using the coloration parameters and absorbance spectra. In response to increasing the length of exposure to rotten shrimp, the absorption spectra of the anthocyanin-encapsulated nanofibrous membrane showed a wavelength blueshift from 580 nm to 412 nm. CNC displayed a diameter of 12–17 nm. The nanoparticle diameter of M/ACY was monitored in the range of 8–13 nm, and the nanofiber diameter was shown in the range of 70–135 nm. Slight changes in comfort properties were monitored after encapsulating M/ACY in the nanofibrous fabric. Full article
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17 pages, 2171 KiB  
Article
Changes in Texture and Collagen Properties of Pork Skin during Salt–Enzyme–Alkali Tenderization Treatment
by Qiang Zou, Yuyou Chen, Yudie Liu, Linghui Luo, Yuhan Zheng, Guilian Ran and Dayu Liu
Foods 2024, 13(20), 3264; https://doi.org/10.3390/foods13203264 - 14 Oct 2024
Cited by 1 | Viewed by 3146
Abstract
The effects of salt–enzyme–alkali progressive tenderization treatments on porcine cortical conformation and collagen properties were investigated, and their effectiveness and mechanisms were analyzed. The tenderization treatment comprised three treatment stages: CaCl2 (25 °C/0–30 min), papain (35 °C/30–78 min), and Na2CO [...] Read more.
The effects of salt–enzyme–alkali progressive tenderization treatments on porcine cortical conformation and collagen properties were investigated, and their effectiveness and mechanisms were analyzed. The tenderization treatment comprised three treatment stages: CaCl2 (25 °C/0–30 min), papain (35 °C/30–78 min), and Na2CO3 (25 °C/78–120 min). The textural, microscopic, and collagenous properties (content, solubility, and structure) of pork skin were determined at the 0th, 30th, 60th, 90th, and 120th min of the treatment process. The results showed that the shear force, hardness, and chewability of the skin decreased significantly (p < 0.05), and the elasticity exhibited a gradual increase with the progression of tenderization. The content and solubility of collagen showed no significant change at the CaCl2 treatment stage. However, the soluble collagen content increased, the insoluble collagen content decreased, and the collagen solubility increased by 18.04% during the subsequent treatment with papain and Na2CO3. Meanwhile, the scanning electron microscopy results revealed that the regular, wavy structure of the pig skin collagen fibers gradually disappeared during the CaCl2 treatment stage, the overall structure revealed expansion, and the surface microscopic pores gradually increased during the papain and Na2CO3 treatment stages. The findings of the Fourier transform infrared spectroscopy analysis indicated that the hydrogen bonding interactions between the collagen molecules and the C=O, N-H and C-N bonds in the subunit structure of collagen were substantially altered during treatment and that the breakage of amino acid chains and reduction in structural ordering became more pronounced with prolonged treatment. In the tertiary structure, the maximum emission wavelength was blue-shifted and then red-shifted, and the fluorescence intensity was gradually weakened. The surface hydrophobicity was slowly increased. The salt–enzyme–alkali tenderization treatment considerably improved the physical properties and texture of edible pork skins by dissolving collagen fibers and destroying the structure of collagen and its interaction force. Full article
(This article belongs to the Section Meat)
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30 pages, 6944 KiB  
Review
Modeling Electronic and Optical Properties of InAs/InP Quantum Dots
by Fujuan Huang, Gaowen Chen and Xiupu Zhang
Photonics 2024, 11(8), 749; https://doi.org/10.3390/photonics11080749 - 10 Aug 2024
Viewed by 2209
Abstract
A theoretical investigation of electronic properties of self-assembled InAs/InP quantum dots (QDs) is presented, utilizing a novel two-step modeling approach derived from a double-capping procedure following QD growth processes, a method pioneered in this study. The electronic band structure of the QD is [...] Read more.
A theoretical investigation of electronic properties of self-assembled InAs/InP quantum dots (QDs) is presented, utilizing a novel two-step modeling approach derived from a double-capping procedure following QD growth processes, a method pioneered in this study. The electronic band structure of the QD is calculated by the newly established accurate two-step method, i.e., the improved strain-dependent, eight-band k p method. The impact of various QD structural parameters (e.g., height, diameter, material composition, sublayer, and inter-layer spacer) on electronic states’ distribution and transition energies is investigated. Analysis of carrier dynamics within QDs includes intraband and interband transitions. The calculation of the carrier transitions between two atomic states, providing insights into optical gain or loss within QDs, is in terms of dipole matrix element, momentum matrix element, and oscillation strength, etc. In addition, the time-domain, traveling-wave method (i.e., rate equations coupled with traveling-wave equations) is used to investigate the optical properties of QD-based lasers. Several optical properties of the QD-based lasers are investigated, such as polarization, gain bandwidth, two-state lasing, etc. Based on the aforementioned method, our key findings include the optimization of carrier non-radiative intraband relaxation through sublayer manipulation, wavelength control through emission blue-shifting and gain bandwidth via variation of sublayer, polarization control of QDs photoluminescence via excited states’ transitions, and the enhancement of two-state lasing in InAs/InP QD lasers by thin inter-layer spacers. This review offers comprehensive insights into QDs electronic band structures and carrier dynamics, providing valuable guidance for optimizing QD-based lasers and their potential designs. Full article
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11 pages, 7295 KiB  
Communication
Phenyl Derivatives Modulate the Luminescent Properties and Stability of CzBTM-Type Radicals
by Quanquan Gou, Jiahao Guan, Lintao Zhang and Xin Ai
Molecules 2024, 29(12), 2900; https://doi.org/10.3390/molecules29122900 - 18 Jun 2024
Cited by 4 | Viewed by 1479
Abstract
The distinctive electron structures of luminescent radicals offer considerable potential for a diverse array of applications. Up to now, the luminescent properties of radicals have been modulated through the introduction of electron-donating substituents, predominantly derivatives of carbazole and polyaromatic amines with more and [...] Read more.
The distinctive electron structures of luminescent radicals offer considerable potential for a diverse array of applications. Up to now, the luminescent properties of radicals have been modulated through the introduction of electron-donating substituents, predominantly derivatives of carbazole and polyaromatic amines with more and more complicated structures and redshifted luminescent spectra. Herein, four kinds of (N-carbazolyl)bis(2,4,6-tirchlorophenyl)-methyl (CzBTM) radicals, Ph2CzBTM, Mes2CzBTM, Ph2PyIDBTM, and Mes2PyIDBTM, were synthesized and characterized by introducing simple phenyl and 2,4,6-trimethylphenyl groups to CzBTM and PyIDBTM. These radicals exhibit rare blueshifted emission spectra compared to their parent radicals. Furthermore, modifications to CzBTM significantly enhanced the photoluminescence quantum yields (PLQYs), with a highest PLQY of 21% for Mes2CzBTM among CzBTM-type radicals. Additionally, the molecular structures, photophysical properties of molecular orbitals, and stability of the four radicals were systematically investigated. This study provides a novel strategy for tuning the luminescent color of radicals to shorter wavelengths and improving thermostability. Full article
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13 pages, 3449 KiB  
Article
(1E)-1,2-Diaryldiazene Derivatives Containing a Donor–π-Acceptor-Type Tolane Skeleton as Smectic Liquid–Crystalline Dyes
by Shigeyuki Yamada, Keigo Yoshida, Yuto Eguchi, Mitsuo Hara, Motohiro Yasui and Tsutomu Konno
Compounds 2024, 4(2), 288-300; https://doi.org/10.3390/compounds4020015 - 17 Apr 2024
Cited by 2 | Viewed by 1632
Abstract
Considerable attention has been paid to (1E)-1,2-diaryldiazenes (azo dyes) possessing liquid–crystalline (LC) and optical properties because they can switch color through thermal phase transitions and photoisomerizations. Although multifunctional molecules with both LC and fluorescent properties based on a donor–π-acceptor (D-π-A)-type tolane [...] Read more.
Considerable attention has been paid to (1E)-1,2-diaryldiazenes (azo dyes) possessing liquid–crystalline (LC) and optical properties because they can switch color through thermal phase transitions and photoisomerizations. Although multifunctional molecules with both LC and fluorescent properties based on a donor–π-acceptor (D-π-A)-type tolane skeleton have been developed, functional molecules possessing LC and dye properties have not yet been developed. Therefore, this study proposes to develop LC dyes consisting of (1E)-1,2-diaryldiazenes with a D–π-A-type tolane skeleton as the aryl moiety. The (1E)-1,2-diaryldiazene derivatives exhibited a smectic phase, regardless of the flexible-chain structure, whereas the melting temperature was significantly increased by introducing fluoroalkyl moieties into the flexible chain. Evaluation of the optical properties revealed that compounds with decyloxy chains exhibited an orange color, whereas compounds with semifluoroalkoxy chains absorbed at a slightly blue-shifted wavelength, which resulted in a pale orange color. The thermal phase transition caused a slight color change accompanied by a change in the absorption properties, photoisomerization-induced shrinkage, and partial disappearance of the LC domain. These results indicate that (1E)-1,2-diaryldiazenes with a D–π-A-type tolane skeleton can function as thermo- or photoresponsive dyes and are applicable to smart windows and in photolithography. Full article
(This article belongs to the Special Issue Feature Papers in Compounds (2024))
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14 pages, 7329 KiB  
Article
Effects of Ferric Ions on Cellulose Nanocrystalline-Based Chiral Nematic Film and Its Applications
by Shuaiqi Wang, Bingqun Lin, Yihan Zeng and Mingzhu Pan
Polymers 2024, 16(3), 399; https://doi.org/10.3390/polym16030399 - 31 Jan 2024
Cited by 3 | Viewed by 1876
Abstract
Chiral nematic materials have been attracting attention in fields of advanced functional applications due to their unique iridescent colors and tunable helical structure. A precisely decreased pitch is of importance for construction and applications of chiral nematic materials; however, it remains a huge [...] Read more.
Chiral nematic materials have been attracting attention in fields of advanced functional applications due to their unique iridescent colors and tunable helical structure. A precisely decreased pitch is of importance for construction and applications of chiral nematic materials; however, it remains a huge challenge. Herein, cellulose nanocrystal (CNC) is selected as a constructed matrix for chiral nematic films, and ferric chloride (FeCl3) is used as a modification agent. We investigate the effects of the ferric ion loads on the helical structure and optical characteristics of iridescent film. Subsequently, the influence of ferric ions on the assembly process of CNC liquid crystal and the regulation of the structure color of self-assembled monolayers are discussed. Therefore, the CNC/FeCl3 chiral nematic films showed a blueshifted structural color from orange to blue, which highlights a simple route to achieve the regulation of decreased pitch. Further, we have applied this CNC/FeCl3 chiral nematic film for benzene gas detection. The sensing performance shows that the CNC/FeCl3 chiral nematic film reacts to benzene gas, which can be merged into the nematic layer of the CNC and trigger the iron ions chelated on the CNC, consequently arousing the redshift of the reflected wavelength and the effective colorimetric transition. This CNC/FeCl3 chiral nematic film is anticipated to boost a new gas sensing mechanism for faster and more effective in-situ qualitative investigations. Full article
(This article belongs to the Section Polymer Membranes and Films)
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17 pages, 1409 KiB  
Article
Parallel Losses of Blue Opsin Correlate with Compensatory Neofunctionalization of UV-Opsin Gene Duplicates in Aphids and Planthoppers
by Markus Friedrich
Insects 2023, 14(9), 774; https://doi.org/10.3390/insects14090774 - 20 Sep 2023
Cited by 3 | Viewed by 1632
Abstract
Expanding on previous efforts to survey the visual opsin repertoires of the Hemiptera, this study confirms that homologs of the UV- and LW-opsin subfamilies are conserved in all Hemiptera, while the B-opsin subfamily is missing from the Heteroptera and subgroups of the Sternorrhyncha [...] Read more.
Expanding on previous efforts to survey the visual opsin repertoires of the Hemiptera, this study confirms that homologs of the UV- and LW-opsin subfamilies are conserved in all Hemiptera, while the B-opsin subfamily is missing from the Heteroptera and subgroups of the Sternorrhyncha and Auchenorrhyncha, i.e., aphids (Aphidoidea) and planthoppers (Fulgoroidea), respectively. Unlike in the Heteroptera, which are characterized by multiple independent expansions of the LW-opsin subfamily, the lack of B-opsin correlates with the presence of tandem-duplicated UV-opsins in aphids and planthoppers. Available data on organismal wavelength sensitivities and retinal gene expression patterns lead to the conclusion that, in both groups, one UV-opsin paralog shifted from ancestral UV peak sensitivity to derived blue sensitivity, likely compensating for the lost B-opsin. Two parallel bona fide tuning site substitutions compare to 18 non-corresponding amino acid replacements in the blue-shifted UV-opsin paralogs of aphids and planthoppers. Most notably, while the aphid blue-shifted UV-opsin clade is characterized by a replacement substitution at one of the best-documented UV/blue tuning sites (Rhodopsin site 90), the planthopper blue-shifted UV-opsin paralogs retained the ancestral lysine at this position. Combined, the new findings identify aphid and planthopper UV-opsins as a new valuable data sample for studying adaptive opsin evolution. Full article
(This article belongs to the Section Insect Molecular Biology and Genomics)
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11 pages, 4490 KiB  
Article
Effects of Thermal-Strain-Induced Atomic Intermixing on the Interfacial and Photoluminescence Properties of InGaAs/AlGaAs Multiple Quantum Wells
by Zhi Yang, Shuai Zhang, Shufang Ma, Yu Shi, Qingming Liu, Xiaodong Hao, Lin Shang, Bin Han, Bocang Qiu and Bingshe Xu
Materials 2023, 16(17), 6068; https://doi.org/10.3390/ma16176068 - 4 Sep 2023
Cited by 4 | Viewed by 2073
Abstract
Quantum-well intermixing (QWI) technology is commonly considered as an effective methodology to tune the post-growth bandgap energy of semiconductor composites for electronic applications in diode lasers and photonic integrated devices. However, the specific influencing mechanism of the interfacial strain introduced by the dielectric-layer-modulated [...] Read more.
Quantum-well intermixing (QWI) technology is commonly considered as an effective methodology to tune the post-growth bandgap energy of semiconductor composites for electronic applications in diode lasers and photonic integrated devices. However, the specific influencing mechanism of the interfacial strain introduced by the dielectric-layer-modulated multiple quantum well (MQW) structures on the photoluminescence (PL) property and interfacial quality still remains unclear. Therefore, in the present study, different thicknesses of SiO2-layer samples were coated and then annealed under high temperature to introduce interfacial strain and enhance atomic interdiffusion at the barrier–well interfaces. Based on the optical and microstructural experimental test results, it was found that the SiO2 capping thickness played a positive role in driving the blueshift of the PL peak, leading to a widely tunable PL emission for post-growth MQWs. After annealing, the blueshift in the InGaAs/AlGaAs MQW structures was found to increase with increased thickness of the SiO2 layer, and the largest blueshift of 30 eV was obtained in the sample covered with a 600 nm thick SiO2 layer that was annealed at 850 °C for 180 s. Additionally, significant well-width fluctuations were observed at the MQW interface after intermixing, due to the interfacial strain introduced by the thermal mismatch between SiO2 and GaAs, which enhanced the inhomogeneous diffusion rate of interfacial atoms. Thus, it can be demonstrated that the introduction of appropriate interfacial strain in the QWI process is of great significance for the regulation of MQW band structure as well as the control of interfacial quality. Full article
(This article belongs to the Topic Electronic and Optical Properties of Nanostructures)
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15 pages, 4368 KiB  
Article
A Polarity-Sensitive Far-Red Fluorescent Probe for Glucose Sensing through Skin
by Lydia Colvin, Dandan Tu, Darin Dunlap, Alberto Rios and Gerard Coté
Biosensors 2023, 13(8), 788; https://doi.org/10.3390/bios13080788 - 4 Aug 2023
Cited by 5 | Viewed by 3376
Abstract
The field of glucose biosensors for diabetes management has been of great interest over the past 60 years. Continuous glucose monitoring (CGM) is important to continuously track the glucose level to provide better management of the disease. Concanavalin A (ConA) can reversibly bind [...] Read more.
The field of glucose biosensors for diabetes management has been of great interest over the past 60 years. Continuous glucose monitoring (CGM) is important to continuously track the glucose level to provide better management of the disease. Concanavalin A (ConA) can reversibly bind to glucose and mannose molecules and form a glucose biosensor via competitive binding. Here, we developed a glucose biosensor using ConA and a fluorescent probe, which generated a fluorescent intensity change based on solvatochromism, the reversible change in the emission spectrum dependent on the polarity of the solvent. The direction in which the wavelength shifts as the solvent polarity increases can be defined as positive (red-shift), negative (blue-shift), or a combination of the two, referred to as reverse. To translate this biosensor to a subcutaneously implanted format, Cyanine 5.5 (Cy5.5)-labeled small mannose molecules were used, which allows for the far-red excitation wavelength range to increase the skin penetration depth of the light source and returned emission. Three Cy5.5-labeled small mannose molecules were synthesized and compared when used as the competing ligand in the competitive binding biosensor. We explored the polarity-sensitive nature of the competing ligands and examined the biosensor’s glucose response. Cy5.5-mannotetraose performed best as a biosensor, allowing for the detection of glucose from 25 to 400 mg/dL. Thus, this assay is responsive to glucose within the physiologic range when its concentration is increased to levels needed for an implantable design. The biosensor response is not statistically different when placed under different skin pigmentations when comparing the percent increase in fluorescence intensity. This shows the ability of the biosensor to produce a repeatable signal across the physiologic range for subcutaneous glucose monitoring under various skin tones. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors and Chemical Sensors)
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