Optical Stability Research Articles

Optical analysis of transesterification reaction assisted by ultrasound

Ultrasound can be used during the biodiesel production reaction, aiming to increase the efficiency of the reaction, as well as reduce the catalyst and alcohol content, facilitating the purification process and minimizing environmental impacts in the production of this biofuel. This work evaluated by optical means the influence of the use of ultrasound on the reaction dynamics of transesterification under different catalyst contents. Tests were conducted using a Langevin-type transducer (40 kHz x 20.5 W) to convert 270 mL of soybean oil per batch. Previous tests in the reactor used showed intense cavitation activity resulting in mass loss of up to 27.3% in erosion tests on aluminum foil. Optical transmittance and ester content evaluation analyzes of the samples showed that ultrasound was able to increase the conversion rate and reduce the optical stabilization time (up to 9.9%), suggesting a shorter reaction time, especially for lower ester contents. catalyst.

Hydroxypropyl Cellulose-Based Meter-Long Structurally Colored Fibers for Advanced Fabrics.

Structurally colored fibers are attractive alternatives to chemically colored fibers due to their rich optical properties, color stability, and environmental friendliness. However, the fabrication of structurally colored fibers using cost-effective raw materials with the possibility to scale up remains challenging. Here, a simple and scalable approach is developed to fabricate continuous meter-long structurally colored fibers exhibiting brilliant structural colors across the visible spectrum and helix orientation-dependent polarization states. The fibers are fabricated by extrusion of concentrated aqueous solutions of chemically crosslinked hydroxypropyl cellulose (HPC). The wavelengths and polarization states can be tuned by solution concentration, relaxation time, and collector's surface energy. The HPC-based structurally colored fibers display excellent optical stability to mechanical straining, repeated drying/water impregnation, and prolonged heating at 150°C. It is demonstrated that the HPC-based structurally colored fibers can be woven into structurally colored fabrics with wavelength- and polarization-coded optical patterns. The current work presents a strategy to tune the chiral nematic order, which constitutes an important step toward mass production of structurally colored fibers with stable and rich optical properties using easily available raw materials.

Rational design and synthesis of pyrrolo-pyridine dinitrile dyes with strong dual-state emission

In recent years, there has been a growing focus on organic dual-state emission (DSE) materials that demonstrate robust luminescence in both solid and solution states. Nevertheless, in the solid state, π-π stacking between organic molecules often results in pronounced luminescence quenching, posing a significant challenge for the design and synthesis of organic DSE materials. In this work, a pyrrolo-pyridine dinitrile (PPDN) dye was synthesized from commercially available 2-heteroaryl acetonitriles and classical diketopyrrolopyrrole (DPP) dye via a two-step process. Due to its special "J"-shaped planar conjugate structure, the PPDN dye has strong DSE performance, high molar extinction coefficients (ε), large Stokes shifts, and excellent optical and thermal stability. It also has aniline vision detection capability, which is useful in the field of security displays and anti-counterfeiting.

Double Layer SiO2-Coated Water-Stable Halide Perovskite as a Promising Antimicrobial Photocatalyst under Visible Light.

Halide perovskite nanocrystals (HPNCs) have emerged as promising materials for various light harvesting applications due to their exceptional optical and electronic properties. However, their inherent instability in water and biological fluids has limited their use as photocatalysts in the aqueous phase. In this study, we present highly water-stable SiO2-coated HPNCs as efficient photocatalysts for antimicrobial applications. The double SiO2 layer coating method confers long-term structural and optical stability to HPNCs in water, while the in situ synthesis of lead- and bismuth-based perovskite NCs into the SiO2 shell enhances their versatility and tunability. We demonstrate that the substantial generation of singlet oxygen via energy transfer from HPNCs enables efficient photoinduced antibacterial efficacy under aqueous conditions. More than 90% of Escherichia coli was inactivated under mild visible light irradiation for 6 h. The excellent photocatalytic antibacterial performance suggests that SiO2-coated HPNCs hold great potential for various aqueous phase photocatalytic applications.

Toward Water-Resistant, Tunable Perovskite Absorbers Using Peptide Hydrogel Additives.

In recent years, hydrogels have been demonstrated as simple and cheap additives to improve the optical properties and material stability of organometal halide perovskites (OHPs), with most research centered on the use of hydrophilic, petrochemical-derived polymers. Here, we investigate the role of a peptide hydrogel in passivating defect sites and improving the stability of methylammonium lead iodide (MAPI, CH3NH3PbI3) using closely controlled, in situ X-ray photoelectron spectroscopy (XPS) techniques under realistic pressures. Optical measurements reveal that a reduction in the density of defect sites is achieved by incorporating peptide into the precursor solution during the conventional one-step MAPI fabrication approach. Increasing the concentration of peptide is shown to reduce the MAPI crystallite size, attributed to a reduction in hydrogel pore size, and a concomitant increase in the optical bandgap is shown to be consistent with that expected due to quantum size effects. Encapsulation of MAPI crystallites is further evidenced by XPS quantification, which demonstrates that the surface stoichiometry differs little from the expected nominal values for a homogeneously mixed system. In situ XPS demonstrates that thermally induced degradation in a vacuum is reduced by the inclusion of peptide, and near-ambient pressure XPS (NAP-XPS) reveals that this enhancement is partially retained at 9 mbar water vapor pressure, with a reduced loss of methylammonium (MA+) from the surface following heating achieved using 3 wt % peptide loading. A maximum power conversion efficiency (PCE) of 16.6% was achieved with a peptide loading of 3 wt %, compared with 15.9% from a 0 wt % device, the former maintaining 81% of its best efficiency over 480 h storage at 35% relative humidity (RH), compared with 48% maintained by a 0 wt % device.

Advancements in Polymer Biomaterials as Scaffolds for Corneal Endothelium Tissue Engineering

Corneal endothelial dysfunction is a leading cause of vision loss globally, frequently requiring corneal transplantation. However, the limited availability of donor tissues, particularly in developing countries, has spurred on the exploration of tissue engineering strategies, with a focus on polymer biomaterials as scaffolds for corneal endotlhelium regeneration. This review provides a comprehensive overview of the advancements in polymer biomaterials, focusing on their role in supporting the growth, differentiation, and functional maintenance of human corneal endothelial cells (CECs). Key properties of scaffold materials, including optical clarity, biocompatibility, biodegradability, mechanical stability, permeability, and surface wettability, are discussed in detail. The review also explores the latest innovations in micro- and nano-topological morphologies, fabrication techniques such as electrospinning and 3D/4D bioprinting, and the integration of drug delivery systems into scaffolds. Despite significant progress, challenges remain in translating these technologies to clinical applications. Future directions for research are highlighted, including the need for improved biomaterial combinations, a deeper understanding of CEC biology, and the development of scalable manufacturing processes. This review aims to serve as a resource for researchers and clinician–scientists seeking to advance the field of corneal endothelium tissue engineering.

Synthesis of Montmorillonite-Silica Nanocomposite Using Millet Husk and Montmorillonite Clay and Optimization of Adsorption Parameters for Congo Red Dye Adsorption

Dyes are substances that, when applied to a substrate provides color by a process that alters, at least temporarily, any crystal structure of the colored substances The discharge of these effluents into the receiving environments results in hazardous health problems as most of these dyes have carcinogenic effects on the living organisms. Generally, dyes are classified into three categories: a) anionic: direct, acid, and reactive dyes; b) cationic: basic dyes; and c) non-ionic: disperse dyes. The chromophores in anionic and non-ionic dyes mostly consist of azo groups or anthraquinone types. However, Congo red, are difficult to biodegrade due to their complex aromatic structures, which provide them with physico-chemical, thermal, and optical stability. This study is aimed at synthesizing Montmorillonite-silica nanocomposite, a cost effective adsorbent from millet husk and Montmorillonite-clay with the determination of its optimum adsorption parameters for Congo Red Dye adsorption. Here, synthesis of Montmorillonite-silica nanocomposite and optimization parameters were carried out using standard procedures. The unbiased result demonstrated that the percentage yield was found to be 94.51 %. The optimum adsorption parameters studied were adsorbent dose, adsorbate concentration, pH and Kinetics studies. The optimum adsorption parameters were found to be 8.0 g/L, 2.0 mg/L, 8 and 30 minutes, respectively. Hence, the synthesized Montmorillonite-silica nanocomposite obtained from montmorillonite clay and millet husk ash can serve as a cost-effective adsorbent for the removal of Congo Red Dye from waste waters.

Efficient Blue Emission in Organic–Inorganic Metal Halide (TEA)2InCl5 Triggered by Bi3+‐Doping

AbstractLead‐free 0D In‐based organic–inorganic metal halides (OIMHs) have attracted tremendous attention because of their nontoxicity, environmental stability, and excellent photoluminescence properties. However, it remains controversial and unclear whether the luminous division exists in ns2 doping In‐based materials, as the majority of In‐based materials are considered non‐luminous. Herein, a series of Bi3+‐doped (TEA)2InCl5 (TEA = tetraethylammonium) crystals are synthesized and it is determined that the blue emission stemmed from Bi ions. Remarkably, the photoluminescence quantum yield (PLQY) of the blue emission at 469 nm reached 69.69% under 371 nm excitation, exceeding those of previously reported Bi3+‐doped OIMHs. In addition, pristine and Bi3+‐doped compounds exhibited excellent structure and optical stability under humid conditions. This study provides new insights into the photoluminescence properties of In‐based OIMHs, especially regarding the high‐efficiency emission of Bi3+‐doped materials.

Structural Modifications due to Bi-Doping in MAPbBr3 Single Crystals and Their Impact on Electronic Transport and Stability.

Doping strategy in lead halide perovskites is essential to enhance its optoelectrical properties and expand the potential applications. In this work, the mechanisms, for how dopants affect the overall structural, optical, electrical, and chemical properties and stability of lead halide perovskite materials, are investigated. This is done by specifically considering various bismuth (Bi)doping concentrations in MAPbBr3 single crystals grown using the inverse temperature crystallization method. The resultant doped single crystals exhibit a saturation point when Bi concentration exceeds 0.063% which is considered an optimum doping point. The highest thermal stability is also achieved at this doping concentration among the doped single crystals. This study clearly identifies how Bi doping affects the properties of MAPbBr3 and extends to consider stability, which has not been fully considered for MA-based perovskites previously. This will provide a clear understanding of evaluating doped perovskite materials for enhanced material properties, device performance, and stability.

Advancements in Optical Resonator Stability: Principles, Technologies, and Applications

This paper provides an overview of the study of optical resonant cavity stability, focusing on the relevant principles, key technological advances, and applications of optical resonant cavities in a variety of high-precision measurement techniques and modern science and technology. Firstly, the vibration characteristics, thermal noise, and temperature characteristics of the reference cavity are presented. Subsequently, the report extensively discusses the advances in key technologies such as mechanical vibration isolation, thermal noise control, and resistance to temperature fluctuations. These advances not only contribute to the development of theory but also provide innovative solutions for practical applications. Typical applications of optical cavities in areas such as laser gyroscopes, high-precision measurements, and gravitational wave detection are also discussed. Future research directions are envisioned, emphasising the importance of novel material applications, advanced vibration isolation technologies, intelligent temperature control systems, multifunctional integrated optical resonator design, and deepening theoretical models and numerical simulations.

Influence of UV irradiation on the luminescence properties of CsPbBr3 perovskite quantum dots and CsPbBr3 perovskite quantum dots/PVDF composite film—for white LED application

Perovskite quantum dots (QDs) have been widely investigated for their excellent properties such as high color purity in displays, tunable emission wavelength, and high photoluminescence quantum yield. For device applications, improving the stability is an area of interest. In this study, the effects of UV irradiation on the structural and luminescence properties of CsPbBr3 perovskite quantum dots (CPB QDs) excited at 365 nm were investigated. To overcome the effects of UV irradiation, a CPB QDs/PVDF composite flexible film was prepared. It exhibits high structural and optical stability under UV irradiation and emits a highly intense green color. The emission wavelength and intensity were observed for three years, and the stability of the temperature-dependent emission intensity up to 400 K has been reported. In addition, it is stable in water. A white LED, fabricated by integrating a blue LED with CPB QDs/PVDF composite film and red phosphor, produces bright natural white light [(CIE x, CIE y) = (0.3704, 0.3611), and CCT = 4177 K] with a color gamut area coverage of 86.4% of the standard NTSC (1953) color space.&#xD.

Systematic optimization of UCNPs-LFA for Helicobacter pylori nucleic acid detection at point-of-care.

Helicobacter pylori (Hp) prevail globally as the primary cause of gastritis, gastric ulcer, and potential gastric cancer, highlighting the need for rapid and precise point-of-care (POC) detection of Hp nucleic acid. Upconversion nanoparticle-based lateral flow assay (UCNPs-LFA) exhibit great potential in POC detection, due to their high optical stability and absence of background fluorescence. However, insufficient sensitivity for nucleic acid detection remains a key challenge. This study systematically optimizes UCNPs-LFA by focusing on target capture, signal transduction, signal separation, and signal analysis, to enhance its detection capabilities for Hp nucleic acid. The optimized UCNPs-LFA platform features a significantly decreased detection limit, a broadened detection range, and high reliability. Results demonstrate that the limit of detection (LOD) is 25 fM, a 105-fold improvement over the initial platform. This systematic optimization strategy is versatile and can be applied to optimize other nanoparticle-based LFAs.

Isolation of Single Donors in ZnO.

The shallow donor in zinc oxide (ZnO) is a promising semiconductor spin qubit with optical access. Single indium donors are isolated in a commercial ZnO substrate using plasma focused ion beam (PFIB) milling. Quantum emitters are identified optically by spatial and frequency filtering. The indium donor assignment is based on the optical bound exciton transition energy and magnetic dependence. The emission stability of these single donors in terms of both intensity and frequency, alongside their transition linewidths less than twice the lifetime limit, highlight the promise of single In donors as optically accessible spin qubits. The optical stability of single donors after FIB fabrication is promising for optical device integration required for scalable quantum technologies based on single donors in direct band gap semiconductors.

Boron Nitride‐Supported Fluorescein Isothiocyanate for Improving Optical Performance and Stability

AbstractOrganic luminogens play an indispensable role in optoelectronic devices, yet there is a pressing need to address their aggregation‐caused quenching (ACQ) and stability. Here we designed and prepared multilayered boron nitride nanosheets/fluorescein isothiocyanate (MBNNSs/FITC) composite phosphors with tunable photoluminescence by controlling the FITC content and annealing temperature. The research results indicate that MBNNSs/FITC with low or high loading of FITC is not conducive to enhancing the emission intensity of FITC, which can be attributed to the fact that low loading leads to a decrease in the content of fluorescent groups, while high loading promotes intermolecular aggregation of FITC dyes. Interestingly, the emission intensity of FITC in MBNNSs/FITC‐6 composite phosphors can be further enhanced by annealing treatment (200 °C), which can be ascribed to the suppression of the ACQ and effective energy transfer from the MBNNSs to the FITC. Moreover, the resultant composite phosphor displays outstanding thermal stability, remarkable photo stability and exceptional water‐resistance. This work provides a new design space for the development of non‐rare‐earth fluorescent materials using organic fluorescent dyes.

A Study of the Optical Properties and Stability of Cs0.33WO3 with Different Particle Sizes for Energy-Efficient Window Films in Building Glazing

Cs0.33WO3 (CWO) is a widely used inorganic material in window films and glass coatings, known for its excellent near-infrared radiation (NIR) blocking property and high visible light transmittance (Tvis). However, the stability of NIR blocking and the optical properties of CWO in the process of application is an urgent and important problem, because significant changes in optical results can impact the related products, such as window films, glass coatings, and so on. In this paper, the particle sizes and optical properties of CWO are tested to study the light stability and their relative relations. The results indicate that CWO particle sizes between 130 nm and 100 nm (D90, the point where 90% of the particles have a diameter smaller than the specified value) exhibit high stability in terms of NIR blocking and visible light transmittance (Tvis). CWO particles with D90 < 100 nm experience a greater reduction in NIR blocking, though this ability significantly recovers upon exposure to sunlight, making these coatings particularly suitable for use in tropical and subtropical climates.

Spectral multiplexing based on multi-distance lensless imaging.

We have demonstrated the capability of spectral multiplexing in multi-distance diffractive imaging, enabling the reconstruction of samples with diverse spectral responses. While previous methods such as ptychography utilize redundancy in radial diffraction data to achieve information multiplexing, they typically require capturing a substantial amount of diffraction data. In contrast, our approach effectively harnesses the redundancy information in axial diffraction data. This significantly reduces the amount of diffraction data required and relaxes the stringent requirements on optical path stability.

Metal-free carbon-dots nanozyme with oxidase-like activity as photocatalysts for highly efficient detection/reduction of Cr(VI) and antibacterial application

Wastewater containing Cr(VI) and bacteria indicated significant challenges and threats to public health and ecological environments. Hence, it is necessary to construct novel method for detecting and treatment such wastewater. Non-metal-doped carbon dots nanozyme (TA-CDs) were effectively synthesized by one-pot hydrothermal method utilizing tartaric acid (TA) and L-tryptophan (L-trp) as ingredients. TA-CDs revealed excellent water solubility, optical stability, and biocompatibility. Particularly noteworthy, TA-CDs (150 μg/mL) exhibited outstanding light-responsive oxidase-like activity, efficiently generating e-, O2∙- and CO2∙-. Furthermore, TA-CDs illustrated an exceptional linear relationship with Cr(VI) in an extensive detection range and low detection limits (0.51 μM), as well as high selectivity and anti-interference properties. Simultaneously, TA-CDs also demonstrated significant photocatalytic activity, achieving approximately 70.26 % reduction in 40 mg/L Cr(VI) and realized excellent antimicrobial performance (inhibition rates of 97.18 % and 82.67 % against E. coli and S. aureus, respectively). In short, this research not only provided a multifunctional carbon-dots nanoenzyme for recognition, photoreduction of Cr(VI), and photodynamic antibacterial application, but also offered novel strategy and methodology for detection and treatment of water containing heavy metals and microorganisms.

Microfluidics and Nanofluidics in Strong Light-Matter Coupling Systems.

The combination of micro- or nanofluidics and strong light-matter coupling has gained much interest in the past decade, which has led to the development of advanced systems and devices with numerous potential applications in different fields, such as chemistry, biosensing, and material science. Strong light-matter coupling is achieved by placing a dipole (e.g., an atom or a molecule) into a confined electromagnetic field, with molecular transitions being in resonance with the field and the coupling strength exceeding the average dissipation rate. Despite intense research and encouraging results in this field, some challenges still need to be overcome, related to the fabrication of nano- and microscale optical cavities, stability, scaling up and production, sensitivity, signal-to-noise ratio, and real-time control and monitoring. The goal of this paper is to summarize recent developments in micro- and nanofluidic systems employing strong light-matter coupling. An overview of various methods and techniques used to achieve strong light-matter coupling in micro- or nanofluidic systems is presented, preceded by a brief outline of the fundamentals of strong light-matter coupling and optofluidics operating in the strong coupling regime. The potential applications of these integrated systems in sensing, optofluidics, and quantum technologies are explored. The challenges and prospects in this rapidly developing field are discussed.

Focus control of a concave–convex ultrasonic gel lens in the radial direction

Optical image stabilization (OIS) systems maintain the three-dimensional focal position of a lens through mechanical actuation systems. This paper examines an optical lens for OIS that utilizes ultrasound vibration to alter the focal position, not only in the depth direction but also in the radial direction. The lens has a simple structure with no mechanical moving parts and consists of an ultrasound transducer divided into four pieces, a glass disk, and a transparent viscoelastic gel film that functions as a lens. The acoustic radiation force generated by the resonant flexural vibration of the glass disk can alter the surface profile of the gel film, allowing for a variable-focus function. The concave and convex lenses can be interchanged using two resonant vibration modes: the standing-wave mode, in which the vibration loop appears at the center, and the traveling-wave mode, in which the vibration node appears at the center. The positions of ultrasound vibrations on the lens can be controlled in a two-dimensional plane by adjusting the driving amplitudes of each channel, thereby achieving focus control in the radial direction. The focusing characteristics of the lens are evaluated through ray-tracing simulation.

A smartphone sensing fluorescent detection of mercury ion based on silicon quantum dots in environment water

Mercury ion (Hg2+) pose a significant hazard to the natural environment. Conventional techniques like Inductively coupled plasma mass spectrometry, X-ray absorption spectroscopy, among others, pose some disadvantages as they demand a lot of money, need trained employees, and cannot provide on-site detection in real-time. A smartphone sensing technique based on silicon quantum dots (Si-QDs) was presented to detect Hg2+ in the environment without the usage of sophisticated equipment. Meanwhile, the technology was built by utilizing a smartphone to capture gray values of fluorescent images of the Si-QDs-Hg2+ system. Microwave-assisted Si-QDs with tiny particle size, high fluorescence, and good optical stability were created. The fluorescence of the Si-QDs was gradually quenched by raising the Hg2+ concentration from 0.5 μmol/L to 5.0 μmol/L for fluorescent detection with a detection limit of 28 nmol/L. The 94.8–97.1 % recovery demonstrated the viability of the Si-QDs approach for detecting Hg2+. Meanwhile, a smartphone sensing strategy was built by recording the gray value of the fluorescent images of the Si-QDs-Hg2+ systems using a smartphone, and the detection limit of the established approach was 3 nmol/L. The accuracy and reliability of the smartphone strategy were verified with the recovery rates of 80.3–92.5 % in tap water and 87.6–109 % in river water. Electron transfer quenching mechanism between Si-QDs and Hg2+ was evidenced by ultraviolet–visible spectroscopy, fluorescent decay curves, cyclic voltammetry, and Zeta potential. Finally, the suggested approach was used to detect Hg2+ in water samples from various environments.