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A free-energy functional is presented to explicitly take into account pair correlations between molecules in inhomogeneous fluids. The framework of classical density functional theory (DFT) is used to describe the variation in the density of molecules interacting through a Mie (generalized Lennard-Jones) potential. Grand Canonical Monte Carlo simulations are performed for the systems to validate the new functional. The statistical associating fluid theory developed for Mie fluids (SAFT-VR Mie) is selected as a reference for the homogeneous bulk limit of the DFT and is applied here to systems of spherical non-associating particles. The importance of a correct description of the pair correlations for a reliable representation of the free energy in the development of the equation of state is duly noted. Following the Barker–Henderson high-temperature expansion, an analogous formulation is proposed from the general DFT formalism to develop an inhomogeneous equivalent of the SAFT-VR Mie free energy as a functional of the one-body density. In order to make use of this new functional in adsorption studies, a non-local version of the DFT is considered, with specific weighted densities describing the effects of neighboring molecules. The computation of these quantities is possible in three-dimensional space for any pore geometry with repulsive or attractive walls. We showcase examples to validate the new functional, revealing a very good agreement with molecular simulation. The new SAFT-DFT approach is well-adapted to describe realistic complex fluids. [ABSTRACT FROM AUTHOR]

Colloidal suspensions made of smart core–shell structures are of current interest in many fields. Their properties come from the possibility of varying the core and shell materials for modifying the composite particles' chemical, biological, and optical properties. These particles are formed with a material with a constant refractive index core and a shell with a refractive index decaying until it matches the solvent refractive index. Poly(N-IsoPropyl AcrylaMide) (PNIPAM) is a typical example of materials forming shells. In this report, we present how to apply Mie scattering theory to predict and understand the static light scattering of large nonhomogeneous colloidal particles with spherical symmetry whose size is comparable with or larger than the light wavelength used for developing scattering experiments, where the Rayleigh–Gans–Debye approximation is not valid. Here, the refractive index decay was approximated by a Gaussian RI profile numerically evaluated through a multilayer sphere. We calculated the form factor functions of suspensions of PNIPAM microgels previously reported and core–shell suspensions made of polystyrene/PNIPAM at 20 and 40 °C synthesized by us. In all the cases, our method succeeded in providing the scattering intensity as a function of the angle. The software for using the numerical method is fairly straightforward and is accessible as an open-source code. The results can not only help predict and understand the photonic properties of microgels with large core–shell structures but also for any particle with a refractive index distribution with spherical symmetry, as in the case of microgels with super chaotropic agents, hollow microgels, or microparticles. [ABSTRACT FROM AUTHOR]

The optical behavior of the square lattices of the hemispherical nanovoids on the surface of the high-refractive-index all-dielectric slabs in the visible range is studied numerically using gallium phosphide as an example. There exist Fano resonances for these metasurfaces for a limited range of thicknesses. The Fano resonances are caused by the interference between the Mie-type scattering resonances of surface pattern elements and the Fabry–Pérot modes of the slabs. The maximum enhancements of the optical Kerr nonlinearity with respect to the bulk material are revealed at the Fano resonances, in particular, for the thinnest nanostructures. Interestingly, no positive correlation between the quality factor and the enhancement of the optical Kerr effect of the metasurface at the Fano resonances is observed. [ABSTRACT FROM AUTHOR]

Dispersant is critical in the ceramic vat photopolymerization (VP) due to its decisive impact on ceramic particle dispersion and suspension stability. However, the mechanisms by which dispersants influence photopolymerization of suspension remain underexplored. In this paper, the effects of the dispersants' refractive index and absorption coefficient on the light intensity distribution within suspension was investigated using a finite element method (FEM) simulation. The results indicate that the absorption coefficient is the primary influencing factor; as the absorption coefficient increases, the light transmittance of the suspension significantly decreases. Additionally, the photopolymerization performances of Al 2 O 3 ceramic suspensions formulated with different dispersants were investigated. We found the mechanisms by which dispersants influence photopolymerization behavior: by affecting light absorption through absorption coefficient and by directly impacting the polymerization reaction through functional groups. The study successfully achieved VP 3D printing of high-precision ceramic architectures with micron-sized features via dispersant optimization. This paper provided a new insight into optimizing fabricating resolution in ceramics VP 3D printing. [ABSTRACT FROM AUTHOR]

Achieving strong circularly polarized luminescence (CPL) responses in chiral inorganic materials is a challenge. Our study reports a synthesis of bismuth bromide oxybate-based inorganic nanomaterials that have been modified with chiral sugar alcohols (D/L-BYE) co-doped with Er3+ and Yb3+. Chiral molecules are used as inducers to preferentially grow the materials towards specific chirality. The Er3+, Yb3+ co-doped chiral sugar alcohol modified BiOBr has stronger luminescence intensity of up-conversion and the near-infrared second region (NIR II) under the excitation of 980 nm. It has been demonstrated that the enhancement of near-infrared and visible luminescence is attributable to electromagnetic field-induced acceleration of radiative excursion and Mie scattering effects. The study proposes a novel approach to simultaneously enhance the up/down conversion luminescence of chiral inorganic nanomaterials doped with rare earth ions. Meanwhile, this material exhibits strong circularly polarized luminescence properties in the visible range, which has great application potential in chiral optics and other fields. [ABSTRACT FROM AUTHOR]

This study explores a combined strategy of Raman and reflectance spectroscopy for quantifying liver fat content and fat droplet size, crucial in assessing donor livers. By using Monte Carlo simulations and experimental setups with oil‐in‐water phantoms, our findings indicate that Raman scattering can solely differentiate between varying fat contents. At the same time, reflectance intensity is influenced by both fat content and oil droplet size, with a more pronounced sensitivity to fat droplet size. This study demonstrates the efficacy of combined Raman and reflectance spectroscopy in assessing liver steatosis and fat droplet size, potentially aiding in assessing donor livers for transplantation. [ABSTRACT FROM AUTHOR]

Structural dyeing has attracted much attention due to its advantages such as environmental friendliness, vivid color, and resistance to fading. Herein, we propose an alternative strategy for fabric coloring based on Cu2O microspheres. The strong Mie scattering effect of Cu2O microspheres enables the creation of vibrant structural colors on fabric surfaces. These colors are visually striking and can potentially be adjusted by tuning the diameter of the microspheres. Importantly, the Cu2O spheres were firmly bonded to the fabrics by using the industrial adhesive PDMS, and the Cu2O structural color fabrics exhibited excellent color fastness to washing, rubbing, and bending. Cu2O structural color fabrics also demonstrated excellent antimicrobial properties against bacteria such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The bactericidal rates of Cu2O structural color textiles after washing for E. coli and S. aureus reached 92.40% and 94.53%, respectively. This innovative approach not only addresses environmental concerns associated with traditional dyeing processes but also enhances fabric properties by introducing vibrant structural colors and antimicrobial functionality. [ABSTRACT FROM AUTHOR]

Colloidal Cu2O nanoparticles can exhibit both photocatalytic activity under visible light illumination and resonant Mie scattering, but, for their practical application, they have to be immobilized on a substrate. Butterfly wings, with complex hierarchical photonic nanoarchitectures, constitute a promising substrate for the immobilization of nanoparticles and for the tuning of their optical properties. The native wax layer covering the wing scales of Polyommatus icarus butterflies was removed by simple ethanol pretreatment prior to the deposition of Cu2O nanoparticles, which allowed reproducible deposition on the dorsal blue wing scale nanoarchitectures via drop casting. The samples were investigated by optical and electron microscopy, attenuated total reflectance infrared spectroscopy, UV–visible spectrophotometry, microspectrophotometry, and hyperspectral spectrophotometry. It was found that the Cu2O nanoparticles integrated well into the photonic nanoarchitecture of the P. icarus wing scales, they exhibited Mie resonance on the glass slides, and the spectral signature of this resonance was absent on Si(100). A novel bio-nanohybrid photonic nanoarchitecture was produced in which the spectral properties of the butterfly wings were tuned by the Cu2O nanoparticles and their backscattering due to the Mie resonance was suppressed despite the low refractive index of the chitinous substrate. [ABSTRACT FROM AUTHOR]

In non-invasive blood glucose measurement, the sensitivity of glucose-induced optical signals within human tissue is a crucial reference point. This study evaluates the sensitivity of glucose-induced diffuse reflectance in the 1000–1700 nm range. A key factor in understanding this sensitivity is the rate at which the scattering coefficient changes due to glucose, as it is significantly higher than in non-living media and predominantly influences the diffuse light signal level when blood glucose levels change. The study measured and calculated the changes in the scattering coefficient at 1314 nm, a wavelength chosen for its minimal interference from glucose absorption and other bodily constituents. Based on the Mie scattering theory and the results at 1314 nm, the changes in the scattering coefficient within the 1000–1700 nm range were estimated. Subsequently, the sensitivity of the glucose signal across this range was determined through Monte Carlo (MC) simulations. The findings from 25 human trials indicate that the measured sensitivities at five other typical wavelengths within this band generally align with the sensitivities calculated using the aforementioned method. This research can guide the identification of blood glucose signals and the selection of wavelengths for non-invasive blood glucose measurements. [ABSTRACT FROM AUTHOR]

We present Subaru/SCExAO + CHARIS broad-band (JHK) integral field spectroscopy of HD 34700 A in polarized light. CHARIS has the unique ability to obtain polarized integral field images at 22 wavelength channels in broad-band, as the incoming light is first split into different polarization states before passing though the lenslet array. We recover the transition disc around HD 34700 A in multiband polarized light in our data. We combine our polarized intensity data with previous total intensity data to examine the scattering profiles, scattering phase functions and polarized fraction of the disc at multiple wavelengths. We also carry out three-dimensional Monte Carlo radiative transfer simulations of the disc using mcfost , and make qualitative comparisons between our models and data to constrain dust grain properties. We find that in addition to micron-sized dust grains, a population of submicron grains is needed to match the surface brightness in polarized light and polarized fraction. This could indicate the existence of a population of small grains in the disc, or it could be caused by Mie theory simulations using additional small grains to compensate for submicron structures of real dust aggregates. We find models that match the polarized fraction of the data but the models do not apply strong constraints on the dust grain type or compositions. We find no models that can match all observed properties of the disc. More detailed modelling using realistic dust aggregates with irregular surfaces and complex structures is required to further constrain the dust properties. [ABSTRACT FROM AUTHOR]

Due to the fact that the vibration and pure rotational Raman signals collected by the temperature and humidity profile lidar were 3–4 orders of magnitude weaker than the Mie scattering signal, they were susceptible to electronic and white noise interference, which seriously affected the system signal-to-noise ratio. In this paper, an improved VMD-WT filtering method was adopted to extract effective signals and denoise. The processing outcome of several filtering algorithms was evaluated, and noisy signals were simulated to confirm the algorithm's efficacy. Based on the quantitative computation of evaluation indicators, such as signal-to-noise ratio, root mean square error, and correlation, the improved VMD-WT algorithm had more significant advantages in indicators such as signal-to-noise ratio. In order to further verify the robustness and adaptability of the proposed algorithm, experimental analysis of the filtering algorithm was conducted on the continuously collected temperature and humidity measured signals. The results demonstrated that the algorithm not only improved the detection range of lidar and suppressed high-altitude noise effectively, but also performed well in processing strong interference signals, like clouds, which led to a significant improvement in the atmospheric optical parameter inversion results. Furthermore, pseudo-color images of aerosols, temperature, and humidity changes over time and space have been used to further illustrate the algorithm's dependability and wide range of potential uses. [ABSTRACT FROM AUTHOR]

Significance: Developing stable, robust, and affordable tissue-mimicking phantoms is a prerequisite for any new clinical application within biomedical optics. To this end, a thorough understanding of the phantom structure and optical properties is paramount. Aim: We characterized the structural and optical properties of PlatSil SiliGlass phantoms using experimental and numerical approaches to examine the effects of phantom microstructure on their overall optical properties. Approach: We employed scanning electron microscope (SEM), hyperspectral imaging (HSI), and spectroscopy in combination with Mie theory modeling and inverse Monte Carlo to investigate the relationship between phantom constituent and overall phantom optical properties. Results: SEM revealed that microspheres had a broad range of sizes with average (13.47 ± 5.98) μm and were also aggregated, which may affect overall optical properties and warrants careful preparation to minimize these effects. Spectroscopy was used to measure pigment and SiliGlass absorption coefficient in the VIS-NIR range. Size distribution was used to calculate scattering coefficients and observe the impact of phantom microstructure on scattering properties. The results were surmised in an inverse problem solution that enabled absolute determination of component volume fractions that agree with values obtained during preparation and explained experimentally observed spectral features. HSI microscopy revealed pronounced single-scattering effects that agree with single-scattering events. Conclusions: We show that knowledge of phantom microstructure enables absolute measurements of phantom constitution without prior calibration. Further, we show a connection across different length scales where knowledge of precise phantom component constitution can help understand macroscopically observable optical properties. [ABSTRACT FROM AUTHOR]

The present study addresses advanced monitoring techniques for particles and airborne molecular contaminants (AMCs) in cleanroom environments, which are crucial for ensuring the integrity of semiconductor manufacturing processes. We focus on quantifying particle levels and a representative AMC, hydrogen chloride (HCl), having known detrimental effects on equipment longevity, product yield, and human health. We have developed a compact laser sensor based on open-path cavity ring-down spectroscopy (CRDS) using a 1742 nm near-infrared diode laser source. The sensor enables the high-sensitivity detection of HCl through absorption by the 2-0 vibrational band with an Allan deviation of 0.15 parts per billion (ppb) over 15 min. For quantifying particle number concentrations, we examine various detection methods based on statistical analyses of Mie scattering-induced ring-down time fluctuations. We find that the ring-down distributions' 3rd and 4th standard moments allow particle detection at densities as low as ~105 m−3 (diameter > 1 μm). These findings provide a basis for the future development of compact cleanroom monitoring instrumentation for wafer-level monitoring for both AMC and particles, including mobile platforms. [ABSTRACT FROM AUTHOR]

The characteristics of subvisible particles (SbVPs) are critical quality attributes of injectable and ophthalmic solutions in pharmaceutical manufacturing. However, current compendial SbVP testing methods, namely the light obstruction method and the microscopic particle count method, are destructive and wasteful of target samples. In this study, we present the development of a non-destructive SbVP analyzer aiming to analyze SbVPs directly in drug product (DP) containers while keeping the samples intact. Custom sample housings are developed and incorporated into the analyzer to reduce optical aberrations introduced by the curvature of typical pharmaceutical DP sample containers. The analyzer integrates a light-sheet microscope structure and models the side scattering event from a particle with Mie scattering theory with refractive indices as prior information. Equivalent spherical particle size under assigned refractive index values is estimated, and the particle concentration is determined based on the number of scattering events and the volume sampled by the light sheet. The resulting analyzer's capability and performance to non-destructively analyze SbVPs in DP containers were evaluated using a series of polystyrene bead suspensions in ISO 2R and 6R vials. Our results and analysis show the particle analyzer is capable of directly detecting SbVPs from intact DP containers, sorting SbVPs into commonly used size bins (e.g. ≥ 2 µm, ≥ 5 µm, ≥ 10 µm, and ≥ 25 µm), and reliably quantifying SbVPs in the concentration range of 4.6e2 to 5.0e5 particle/mL with a margin of ± 15 % error based on a 90 % confidence interval. [ABSTRACT FROM AUTHOR]

We present laboratory measurements of angular light scattering intensity for aerosolized, micron-sized, irregularly shaped aluminum oxide (Al2O3) abrasive powders with different grit sizes. The measurements were carried out with the scattering angle ranging from 0.32° to 177.6°. First, we demonstrate that the light scattering inferred diameters were in good agreement with the intensity-weighted mean sizes and discuss the importance of intensity-weighted size distributions. Second, the wide range of scattering angles motivated us to visualize the same scattering intensity data with three methods: (a) logarithmically versus linear scattering angle θ, (b) logarithmically versus the logarithmic magnitude of the scattering wave vector q for forward scattering, the method of Q − space analysis, and (c) logarithmically (last ≈ 20 degrees of θ) versus linear phase angle (180° - θ). The combination of these viewpoints yields a comprehensive description of the scattering that corresponds to dividing angular scattering into three regimes: forward−, side–, and back − scattering. The light scattering measurements were compared to the Mie scattering calculated for homogenous, spherical particles with the same volume-equivalent size distribution as that of the Al2O3 particles determined with an aerodynamic particle sizer. Experimental and Mie-theory results were well-matched in the forward regime which is clearly shown in Q − space but showed a poor matching in the side and backscattering regimes, as displayed in θ− and (180°- θ) space, respectively. [ABSTRACT FROM AUTHOR]

With the aid of 3D full‐field finite difference time–domain simulations, model configurations for CsPbI3$\left(\text{CsPbI}\right)_{3}$ thin‐film solar cell devices that include periodically arranged TiO2$\left(\text{TiO}\right)_{2}$ microspheres, exhibiting resonating whispering gallery modes (WGMs), are proposed. The TiO2$\left(\text{TiO}\right)_{2}$ microspheres present, either immersed in perovskite or coated with perovskite layer, between the electron‐ and hole‐transport layers show enhanced current‐conversion efficiency. The presence of WGMs lead to enhancement in the absorption of CsPbI3$\left(\text{CsPbI}\right)_{3}$ layer. The incoming electromagnetic wave couples with TiO2$\left(\text{TiO}\right)_{2}$ microsphere and forms confined resonating modes. Different designs are examined for deciding the appropriate position of WGM exhibiting spheres with respect to thin‐film perovskite solar cell (PSC) featuring back reflector and optimized antireflectance coating. Since the incoupling element is lossless, energy stored in microspheres is absorbed efficiently by the underlying active material. This directly contributes to the increment in the current density of the solar cell. Thus, the devices show a higher current density of 23.62 mA cm−1, while that in planar solar cell device shows current density of 13.68 mA cm−1, for the same thickness of perovskite layer. This leads to more than 70% enhancement in the short‐circuit current density than the conventional PSCs device of similar size. [ABSTRACT FROM AUTHOR]

In this work we present a formalism based on scalar Green's functions to deal with electromagnetic scattering problems. Although the formulations of the Mie theory and Born approximations in terms of electromagnetic scattering are well known and relevant, they have certain disadvantages: complexity, computational time, few symmetries, etc. Therefore, the study with scalar Green's functions allows dealing with these problems with greater simplicity and efficiency. However, the information provided by the vector formulation is sacrificed. Nevertheless, different cases of electromagnetic scattering of dielectric media with different dimensions, geometries and refractive indices will be presented. Thus, we will be able to verify the capacity of this scalar method in predicting light-scattering problems. [ABSTRACT FROM AUTHOR]

Since the 1920s, the Enskog solutions to the Boltzmann equation have provided a route to predicting the transport properties of dilute gas mixtures. At higher densities, predictions have been limited to gases of hard spheres. In this work, we present a revised Enskog theory for multicomponent mixtures of Mie fluids, where the Barker–Henderson perturbation theory is used to calculate the radial distribution function at contact. With parameters of the Mie-potentials regressed to equilibrium properties, the theory is fully predictive for transport properties. The presented framework offers a link between the Mie potential and transport properties at elevated densities, giving accurate predictions for real fluids. For mixtures of noble gases, diffusion coefficients from experiments are reproduced within ±4%. For hydrogen, the predicted self-diffusion coefficient is within 10% of experimental data up to 200 MPa and at temperatures above 171 K. Binary diffusion coefficients of the CO2/CH4 mixture from simulations are reproduced within 20% at pressures up to 14.7 MPa. Except for xenon in the vicinity of the critical point, the thermal conductivity of noble gases and their mixtures is reproduced within 10% of the experimental data. For other molecules than noble gases, the temperature dependence of the thermal conductivity is under-predicted, while the density dependence appears to be correctly predicted. Predictions of the viscosity are within ±10% of the experimental data for methane, nitrogen, and argon up to 300 bar, for temperatures ranging from 233 to 523 K. At pressures up to 500 bar and temperatures from 200 to 800 K, the predictions are within ±15% of the most accurate correlation for the viscosity of air. Comparing the theory to an extensive set of measurements of thermal diffusion ratios, we find that 49% of the model predictions are within ±20% of the reported measurements. The predicted thermal diffusion factor differs by less than 15% from the simulation results of Lennard-Jones mixtures, even at densities well exceeding the critical density. [ABSTRACT FROM AUTHOR]

We develop a physically based equation of state that describes Mie ν-6 fluids with an accuracy comparable to that of state-of-the-art empirical models. The equation of state is developed within the framework of the uv-theory [T. van Westen and J. Gross, J. Chem. Phys. 155, 244501 (2021)], which is modified by incorporating the third virial coefficient B3 in the low-density description of the model. The new model interpolates between a first-order Weeks–Chandler–Andersen (WCA) perturbation theory at high densities and a modified first-order WCA theory that recovers the virial expansion up to B3 at low densities. A new algebraic equation for the third virial coefficient of Mie ν-6 fluids is developed—other inputs are taken from previous work. Predicted thermodynamic properties and phase equilibria are compared to a comprehensive database of molecular simulation results from the literature, including Mie fluids of repulsive exponents 9 ≤ ν ≤ 48. The new equation of state is applicable to states with densities up to ρ * ( T * ) ⪅ 1.1 + 0.12 T * and temperatures T* > 0.3. For the Lennard-Jones fluid (ν = 12), the performance of the model is comparable to that of the best empirical equations of state available. As compared to empirical models, the physical basis of the new model provides several advantages, however: (1) the new model is applicable to Mie fluids of repulsive exponents 9 ≤ ν ≤ 48 instead of only ν = 12, (2) the model leads to a better description of the meta-stable and unstable region (which is important for describing interfacial properties by classical density functional theory), and (3) being a first-order perturbation theory, the new model (potentially) allows an easier and more rigorous extension to non-spherical (chain) fluids and mixtures. [ABSTRACT FROM AUTHOR]

Overshadowed by the electric dipole ones, the magnetic dipole transitions of a quantum emitter are hard to probe. This can be remedied by using pure magnetic hotspots, which host strong magnetic but quite weak electric fields in a subwavelength region. Utilizing the multiparticle Mie theory, we demonstrate pure magnetic hotspots via hollow silicon nanoparticles arranged in a ring configuration and illuminated by Bessel cylindrical vector beams. Normalized local field admittances of about 10 5 – 10 7 and magnetic field enhancements of about 10–30 are achievable. Moreover, the peak of the magnetic field enhancement can be shifted about 370 nm via the hollow size. In other words, the pure magnetic hotspot can be optimized for a particular magnetic dipole transition. [ABSTRACT FROM AUTHOR]

The light absorption enhancement (Eabs) of black carbon (BC) coated with non‐BC materials is crucial in the assessment of radiative forcing, yet its evolution during photochemical aging of plumes from biomass burning, the globe's largest source of BC, remains poorly understood. In this study, plumes from open burning of corn straw were introduced into a smog chamber to explore the evolution of Eabs during photochemical aging. The light absorption of BC was measured with and without coating materials by using a thermodenuder, while the size distributions of aerosols and composition of BC coating materials were also monitored. Eabs was found to increase initially, and then decrease with an overall downward trend. The lensing effect dominated in Eabs at 520 nm, with an estimated contribution percentages of 47.5%–94.5%, which is far greater than light absorption of coated brown carbon (BrC). The effects of thickening and chemical composition changes of the coating materials on Eabs were evaluated through comparing measured Eabs with that calculated by the Mie theory. After OH exposure of 1 × 1010 molecules cm−3 s, the thickening of coating materials led to an Eabs increase by 3.2% ± 1.6%, while the chemical composition changes or photobleaching induced an Eabs decrease by 4.7% ± 0.6%. Simple forcing estimates indicate that coated BC aerosols exhibit warming effects that were reduced after aging. The oxidation of light‐absorbing CxHy compounds, such as polycyclic aromatic hydrocarbons (PAHs), to CxHyO and CxHyO>1 compounds in coating materials may be responsible for the photobleaching of coated BrC. Plain Language Summary: Understanding how black carbon (BC) coated with non‐BC materials affects light absorption is crucial for assessing its impact on the Earth's climate. However, there is limited knowledge about how this process changes when BC, particularly from biomass burning, is exposed to light. Biomass burning is a significant global source of BC. This study investigated the changes in light absorption of BC from burning corn straw as it aged in a controlled environment. We measured the light absorption of BC with and without its coating materials. Our results showed that the main cause of increased light absorption was the lensing effect of the coating materials, which was more significant than the light absorption by the coating materials themselves. We also discovered that as the coating materials thickened, BC absorbed more light. However, changes in the chemical composition of the coating materials led to a decrease in total absorption. These findings suggest that while coated BC initially has a warming effect on the climate, this effect diminished as the BC ages. The decrease is likely due to the breakdown of light‐absorbing compounds in the coating materials, such as polycyclic aromatic hydrocarbons (PAHs). Key Points: Photochemical evolution of light absorption enhancement (Eabs) of black carbon from corn straw burning was studied in a chamberAfter an initial increase Eabs decreased and then remained unchanged during photochemical agingThe photobleaching impacted more on Eabs than the thickening of coating aerosols during photochemical aging [ABSTRACT FROM AUTHOR]

Electrochromic materials (ECMs), the colors of which can be electrically modulated by small driving voltages with a unique open‐circuit memory effect, are in great demand in various application fields. However, traditional ECMs exhibit a narrow modulation range of color gamut under the electric stimulus, owing to the monotonous chemical coloration in an absorption manner. Multicolor ECMs with optical nanostructures can greatly extend the color gamut by incorporating complex optical interactions such as interference and diffraction. Mie scatterer nanospheres (MSNSs) are a kind of nanospheres with unique optical structures that can simply exhibit and change vivid structural colors by adjusting their diameters. Herein, this work reports multicolor ECMs based on MSNSs with polymer shells of poly‐3,4‐ethylenedioxythiophene (PEDOT) and poly‐pyrrole (PPY). They possess a superior optical modulation capability with a wide color gamut, a fast response rate, a visible‐angle‐independence, etc. Additionally, a nano‐dispersion strategy is used to prepare mixed electrochromic pigments with a nanoscale uniformity, further broadening the color gamut tunability. Simulations in wave optics and Mie scattering theory are conducted to unveil the multicolor modulation mechanism, demonstrating the interactions of MSNSs with incident lights. This work provides a feasible approach for fabricating multicolor ECMs with more application potential. [ABSTRACT FROM AUTHOR]

In the context of autonomous driving, the augmentation of existing data through simulations provides an elegant solution to the challenge of capturing the full range of adverse weather conditions in training datasets. However, existing physics-based augmentation models typically rely on single scattering approximations to predict light propagation under unfavorable conditions, such as fog. This can prevent the reproduction of important signal characteristics encountered in a real-world environment. Consequently, in this work, Monte Carlo simulations are employed to assess the relevance of multiple-scattered light to the detected LiDAR signal in different types of fog, with scattering phase functions calculated from Mie theory considering real particle size distributions. Bidirectional path tracing is used within the self-developed GPU-accelerated Monte Carlo software to compensate for the unfavorable photon statistics associated with the limited detection aperture of the LiDAR geometry. To validate the Monte Carlo software, an analytical solution of the radiative transfer equation for the time-resolved radiance in terms of scattering orders is derived, thereby providing an explicit representation of the double-scattered contributions. The results of the simulations demonstrate that the shape of the detected signal can be significantly impacted by multiple-scattered light, depending on LiDAR geometry and visibility. In particular, double-scattered light can dominate the overall signal at low visibilities. This indicates that considering higher scattering orders is essential for improving AI-based perception models. [ABSTRACT FROM AUTHOR]

This study presents the hygroscopic properties of aerosols from the Arctic free troposphere by means of contemporary lidar and radiosonde observations only. It investigates the period from the Arctic Haze in spring towards the summer season in 2021. Therefore, a one-parameter growth curve model is applied to lidar data from the Koldewey Aerosol Raman Lidar (AWIPEV in Ny-Ålesund, Svalbard) and simultaneous radiosonde measurements. Hygroscopic growth depends on different factors like aerosol diameter and chemical composition. To detangle this dependency, three trends in hygroscopicity are additionally investigated by classifying the aerosol first by its dry color ratio, and then by its season and altitude. Generally, we found a complex altitude dependence with the least hygroscopic particles in the middle of the troposphere. The most hygroscopic aerosol is located in the upper free troposphere. A hypothesis based on prior lifting of the particles is given. The expected trend with aerosol diameter is not observed, which draws attention to the complex dependence of hygroscopic growth on geographical region and altitude, and to the development of backscatter with the aerosol size itself. In a seasonal overview, two different modes of stronger or weaker hygroscopic particles are additionally observed. Furthermore, two special days are discussed using the Mie theory. They show, on the one hand, the complexity of analyzing hygroscopic growth by means of lidar data, but on the other hand, they demonstrate that it is in fact measurable with this approach. For these two case studies, we calculated that the aerosol effective radius increased from 0.16 μ m (dry) to 0.18 μ m (wet) and from 0.28 μ m to 0.32 μ m for the second case. [ABSTRACT FROM AUTHOR]

Due to the influence of geometric factors, the temperature and humidity profile of lidar's near-field signal was warped when sensing the air environment. In order to perform geometric factor correction on near-field signals, this article proposes different correction solutions for the Mie and Raman scattering channels. Here, the Mie scattering channel used the Raman method to invert the aerosol backscatter coefficient and correct the extinction coefficient in the transition zone. The geometric factor was the ratio of the measured signal to the forward-computed vibration Raman scattering signal. The aerosol optical characteristics were reversed using the corrected echo signal, and the US standard atmospheric model was added to the missing signal in the blind zone, reflecting the aerosol evolution process. The stability and dependability of the proposed algorithm were validated by the consistency between the visibility provided by the Environmental Protection Agency and the visibility acquired via lidar retrieval data. The near-field humidity data were supplemented by the interpolation method in the Raman scattering channel to reflect the water vapor transfer process in the temporal dimension. The measured transmittance curve of the filter, the theoretical normalized spectrum, and the sounding data were used to compute the delay geometric factor. The temperature was retrieved and the near-field signal distortion issue was resolved by applying the corrected quotient of the temperature channel. The proposed algorithm exhibited robustness and universality, enhancing the system's detection accuracy compared to the temperature and humidity data constantly recorded by the probes in the meteorological gradient tower, which have a high correlation with the lidar observation data. The comparison between lidar data and instrument monitoring data showed that the proposed algorithm could effectively correct distorted echo signals in the transition zone, which was of great value for promoting the application of lidar in the meteorological monitoring of the urban canopy layer. [ABSTRACT FROM AUTHOR]

Prospects for the application of orbital lidars for the detection of gas leaks from spacecrafts are investigated. The optical characteristics of the main light-scattering components – molecules and atoms of gases, are estimated at altitudes of 100–600 km from the Earth surface. It is shown that an orbital lidar with modern technical parameters can reliably detect signals from dispersed gas leak components at distances from several tens to one hundred meters from the spacecraft. [ABSTRACT FROM AUTHOR]

Nanoscale particles described by Mie resonance in the UV–vis–NIR region are in high demand for optical applications. Controlling the shape and size of these particles is essential, as it results in the ability to control the wavelength of the Mie resonance peak. In this work, we study the extensive scattering properties of gadolinium niobate particles with complex bar- and cube-like shapes in the UV–vis–NIR region. We perform our experimental analysis by characterizing the morphology and extinction spectra, and our theoretical study by implementing a Mie scattering model for a distribution of spherical particles. We can accurately model the size distribution and extinction spectra of complex shaped particles and isolate the contribution of aggregates to the extinction spectra. We can separate the contributions of dipoles, quadrupoles, and octupoles to the Mie resonances for their respective electric and magnetic parts. Our results show that we can tune the broad Mie resonance peak in the extinction spectra by the nanoscale properties of our system. This behavior can aid in the design of lasing and luminescence-enhanced systems. These dielectric gadolinium niobate submicron particles are excellent candidates for light manipulation on the nanoscale. [ABSTRACT FROM AUTHOR]

Range-resolved CH4 concentration measurement is important prior data for atmospheric physical and chemical models. Ground-based differential absorption lidar (DIAL) can measure the vertical distribution of CH4 concentration in the atmosphere. The traditional method uses lidar observational data and the lidar equation to calculate profiles, but the inversion accuracy is greatly affected by noise. Although some denoising methods can improve accuracy at low altitudes, the low signal-to-noise ratio caused by the effect of aerosol Mie scattering and lower aerosol concentrations at high altitudes cannot be solved. Here, an improved cubic smoothing spline fitting CH4 concentration profile inversion method is proposed to address this challenge. By adding a penalty term of the second derivative of the conventional cubic spline function to the objective function, this penalty term acts to smooth the fitting, allowing the fitting function to avoid necessarily passing through those noisy sampling points. This avoids the large fluctuations caused by noisy sampling points, effectively suppresses noise, captures signals with lower noise levels, and thereby enhances the inversion accuracy of the profiles. Simulations and case studies demonstrated the superiority of the proposed method. Compared with the traditional method, cubic smoothing spline fitting can reduce the mean error of the whole CH4 profile by 85.54%. The standard deviation of CH4 concentration retrieved is 3.59 ppb–90.29 ppb and 0.01 ppb–6.75 ppb smaller than the traditional method and Chebyshev fitting, respectively. Three real cases also indicate that the CH4 concentration retrieved by cubic smoothing spline fitting is more consistent with in-situ measurements. In addition, long-term DIAL observations have also revealed notable diurnal and seasonal trends in CH4 concentration at observation sites. [ABSTRACT FROM AUTHOR]

Recently, CNN-based all-in-one image enhancement methods have been proposed to solve multiple image degradation tasks. However, these CNN-based methods usually have two limitations. One limitation is that they usually design a specific encoder for each image enhancement task, lacking of a unified and simple framework. The other limitation is that they can not effectively capture global image degradation information, as use of the CNN-based encoders has a limited local receptive field. In this work, we propose a TransEncoder-based All-in-one Image Enhancement Network (TAENet), with a single encoder and a decoder, for simultaneously handling multiple image enhancement tasks. Specifically, we propose a Transformer-based Encoder (TransEncoder), which introduces instance normalization to transformer for color recovery. The TransEncoder model global degradation information by using the transformer's global self-attention mechanism. Additionally, inspired by the Mie scattering model, we propose a novel depth loss function for perceiving image depth information by minimizing the depth difference between the enhanced image and the ground-truth, thus further improving model performance. Moreover, a novel contrastive loss is introduced to strengthen task-generalization performance by enhancing the model's representation capability. Experiments show that the TAENet outperforms 24 state-of-the-art methods on image dehazing, image deraining, and low-light image enhancement. [ABSTRACT FROM AUTHOR]

The K3LuSi2O7 phosphor doping Eu2+ rare-earth ions (KLS:Eu) was reported to possess broad emission band from near-ultraviolet to nearinfrared. Additionally, this phosphor showed a wide absorption band of 250-600 nm, allowing it to be excited by blue-light chip of 460 nm, making it one of the suitable phosphor materials for a light emitting diode (LED). Besides, the scattering particle material CaCO3 is incorporated into the yellow phosphor layer to serve the scattering-enhancement purpose. The combination of both materials aims at accomplishing improvements in performance of commercial LED package. The concentration of KLS:Eu is constant while that of CaCO3 is modified. As a result, the scattering factor is regulated and become the key factor influencing the optical outputs of the simulated LED. The increasing CaCO3 concentration enhances the phosphor scattering efficiency of light, helping to improve the lumen output and colortemperature consistency of the LED. However, the color rendering performance declines as a function of the CaCO3 growing amount, despite the presence of a KLS:Eu phosphor layer. Further works should be done to optimize the application of KLS:Eu in cooperation with scattering particles for a higher-quality LED device. [ABSTRACT FROM AUTHOR]

Under the synergistic effect of Mie scattering and dimethyl sulfoxide (DMSO) ligand modification, a novel linear variable PbS-DMSO filter obtained by regulating the quantity and spacing of PbS-DMSO nanoparticles exhibits continuous variable filtering capability in the wide spectral range of 500-1100 nm, with significant slope and cutoff depth of filtering. The surface modification of PbS quantum dots (QDs) with DMSO drastically enhances the light absorption, thereby increasing the cutoff depth and slope of filtering. Moreover, the modification of PbS QDs with DMSO also results in the aggregation of PbS QDs into nanoparticles with an average diameter of ∼100 nm, providing conditions for the generation of the Mie scattering effect. Based on the Mie scattering effect, by regulating the quantity and spacing of PbS-DMSO nanoparticles, not only can the absorption characteristics of PbS-DMSO nanoparticles be further enhanced to improve the cutoff depth and slope of filtering but also the absorption wavelength range can be well adjusted to achieve arbitrary adjustment of the filtering spectral range. Combined with an image sensor, the spectral reconstruction ability of the linear variable PbS-DMSO filter is further demonstrated, which provides a research idea for breaking through the limitation of the number of sampling points in traditional array QD filters. [ABSTRACT FROM AUTHOR]

Winter continues to witness numerous automobile accidents attributed to graupel and hail precipitation in Japan. Detecting these weather phenomena using radar technology holds promise for reducing the impact of such accidents and improving road maintenance operations. Weather radars operating at different frequencies, such as C- and X-band, prove effective in graupel detection by analyzing variations in backscattered signals within the same radar volume. When particle diameters exceed 5 mm, the study of Mie scattering characteristics across different melting ratios reveals insights. The dual frequency ratio (DFR) shows potential for graupel detection. The DFR presents wider variations with ten-times difference in melting ratios with increased density, offering opportunities for precise detection. Additionally, the DFR amplitude rises with temperature changes. However, for hydrometeor diameters below approximately 3 mm, and within the Rayleigh region, the DFR exhibits minimal fluctuations. Hence, this technique is best suited for diameters exceeding 3 mm for optimal efficacy. Additionally, a "detection alert" for graupel/hail has been proposed. Based on this alert, and with realistic rain/graupel size distributions, graupel/hail can be detected with an approximate probability of 70%. [ABSTRACT FROM AUTHOR]

The role of various light scattering phenomena in aesthetics and clinical practice is explored in this review. Four main types of light scattering, Tyndall, Rayleigh, Mie, and Raman, are discussed. Each type is explained in terms of its physical principles and its applications in aesthetic medicine. Tyndall scattering is relevant in understanding the blue appearance of certain dermal fillers. Rayleigh scattering contributes to skin tone perception and plays a role in certain laser treatments. Mie scattering is important in laser hair removal and the appearance of skin conditions like melasma. Raman scattering, while primarily used in research, shows promise for non‐invasive skin analysis, personalized skincare, treatment monitoring, and early skin cancer detection. It is important to understand these scattering phenomena for optimizing light‐based aesthetic procedures and developing effective treatments. Properly applying the appropriate scattering theory based on relative particle size is crucial in clinical aesthetic practice. [ABSTRACT FROM AUTHOR]

Aquasols produced by exploding copper wires represent complex systems in which identifying individual colloidal components poses challenges due to broad and multimodal size distributions and varying shares among oxidation states. To evaluate the reproducibility of copper wire explosion, the size distribution of metallic and oxidized colloidal components within the 10–300 nm diameter range was assessed. Classification of each individual particle into bins according to size and chemical composition was accomplished by reconstructing the recorded optical extinction spectra of three sols produced under identical conditions as the weighted sum of the extinction spectra of individual copper and copper-oxide particles, computed using Mie theory. Our spectrophotometry-based component analysis revealed differences in particle number concentrations of the mainly oxidized nanoparticles, corresponding to deviations observed in the ultraviolet portion of the extinction spectra. Notable uniformity was observed, however, in the number of metallic fine particles, consistent with agreement in spectral features in the visible range. Regarding mass concentration, practically no differences were observed among the three samples, with nano-to-fine ratios of copper particles agreeing within 0.45%. Despite the complex processes during explosion leading to limited reproducibility in the ratio of different copper oxidation states, very good reproducibility (54.2 ± 0.7%) was found when comparing the total copper content of the samples to the mass of the exploded copper wire. [ABSTRACT FROM AUTHOR]

Nanomechanical resonators provide a versatile platform for nanoscale mass sensing and force microscopy, as well as for enhancing light‐matter interaction offering unique functionality for optomechanical applications. In this way, discovering new approaches for coupling light with the mechanical degrees of freedom opens the strong desire paths for further developing of nanomechanical technology. Here, the parametric optothermal modulation of hybrid nanomechanical systems consisting of carbon nanowire with a silicon nanoparticle on its top, is reported. The mechanism of the modulation is based on the periodic optical heating of the nanowire and further modulation of the elasticity parameters. Utilizing the silicon nanoparticle provides additional functionality owing to optical absorption enhanced with Mie resonance and the unique feature of optical Raman thermometry enabling optical monitoring of local temperature. It is shown that the parametric mechanism of modulation allows for a significant increase of the optomechanical coupling strength. [ABSTRACT FROM AUTHOR]

Passive daytime radiative cooling has emerged as a promising green technology for the thermal management of buildings, vehicles, textiles, and electronics. Typically, both high solar reflectance and high thermal emissivity are prerequisites to achieve sufficient daytime cooling. However, colored radiative cooling materials are facing the dilemma of introducing visible light absorption, leading to challenges in balancing cooling and aesthetic demands. Here, three colored bilayer radiative cooling coatings, each comprised of a white base layer and a colored top layer with fluorescence enhancement are fabricated. Three phosphors (Sr2Si5N8:Eu2+, Y3Al5O12:Ce3+, and (Ba,Sr)SiO4:Eu2+) are employed with respective photoluminescence quantum yields (PLQYs) of 81%, 95.8%, and 91.0% as the colored pigment in the top layer. To mitigate the contradiction between coloration and solar reflectance, SiO2 microspheres are introduced into the top layer and utilize their Mie‐resonance‐based multiple scattering to increase the photoluminescent (PL) properties of the phosphors, which jointly boosts the effective solar reflectance (ESR) of the top layer. As a result, the three bilayer coatings exhibit soft colors while achieving subambient cooling with temperature drops of up to 1.5 °C. This fluorescence‐enhancement strategy may pave the way for preparing highly efficient radiative cooling coatings with tunable colors. [ABSTRACT FROM AUTHOR]

Methylene blue dye, being toxic, carcinogenic and non-biodegradable, poses a serious threat for human health and environmental safety. The effective and time-saving removal of such industrial dye necessitates the use of innovative technologies such as silver nanoparticle-based catalysis. Utilizing a pulsed Nd:YAG laser operating at the second harmonic generation of 532 nm with 2.6 J energy per pulse and 10 ns pulse duration, Ag nanoparticles were synthesized via an eco-friendly method with sodium dodecyl sulphate (SDS) as a capping agent. Different exposure times (15, 30, and 45 min) resulted in varying nanoparticle sizes. Characterization was achieved through UV–Vis absorption spectroscopy, scanning electron microscopy (SEM) imaging, and energy dispersive X-ray (EDX). Lorentzian fitting was used to model nanoparticle size, aligning well with SEM results. Mie's theory was applied to evaluate the absorption, scattering, and extinction cross-sectional area spectra. EDX revealed increasing Ag and carbon content with exposure time. The SDS-caped AgNPs nanoparticles were tested as catalyst for methylene blue degradation, achieving up to 92.5% removal in just 12 min with a rate constant of 0.2626 min−1, suggesting efficient and time-saving catalyst compared to previously reported Ag-based nanocatalysts. [ABSTRACT FROM AUTHOR]

To maintain a comfortable indoor living environment in low latitude or tropical regions, humans consume significant amounts of electrical energy in air conditioning, leading to substantial CO2 emissions. Passive daytime radiative cooling (PDRC) allows objects to cool down during the daytime without any energy consumption by dissipating heat through the atmospheric transparency window (8−13 µm) to outer space, which has garnered significant attention. However, the practical applications of common PDRC materials are hindered by their poor optical selectivity and high‐reflective silver backing. Additionally, the availability of artificial photon emitters with complex structures and excellent performance is also limited by their high cost. Herein, a novel multilayer prismatic photonic metamaterial film without any silver reflector, easily scalable and produced by a roll‐to‐roll method is demonstrated, which exhibits ≈96.4% sunlight reflectance (0.3−2.5 µm) and ≈97.2% emissivity in mid‐infrared (IR) (8−13 µm). At an average solar intensity of ≈920 W m−2, it is on average 6.8 °C below ambient temperature during the day and theoretically yields a radiative cooling power of 88.9 W m−2. Furthermore, the film exhibits excellent hydrophobicity, superior flexibility, and robust mechanical strength, providing an attractive and viable pathway for practical applications addressing the pressing challenges of climate and energy issues. [ABSTRACT FROM AUTHOR]

The scattering of x linearly polarized non-diffracting Lommel beam by a perfect electromagnetic conductor (PEMC) sphere is analyzed within the generalized Lorenz–Mie theory (GLMT) framework. The electromagnetic fields of the incident Lommel beams are expressed by employing spherical vector wave functions (SVWFs) and beam shape coefficients (BSCs). These BSCs are mainly considered in the expression of shaped beams in the GLMT with slight beam axicon angle. The scattered electromagnetic fields are constructed using unknown scattering field coefficients (SFCs) and SVWFs. These undetermined SFCs are calculated employing boundary conditions (BCs) at the PEMC surface. The expressions of the far-region/far-zone scattering intensity (FSI) are given and computed. The influences of Lommel beam configuration parameters like as beam order, beam half cone angle, beam asymmetry parameter, beam center coordinates positions, and PEMC sphere size parameter in addition to PEMC scalar admittance on the FSI are analyzed and discussed. The experience of this research work will be quite helpful in analyzing optical radiation force and torque, electromagnetic scattering, light manipulation, antenna engineering domain, optical tweezers, particle interaction, and trapping. Moreover, findings of the study can also be extended to study the interaction between the non-diffracting Lommel beam and the metamaterial structures. [ABSTRACT FROM AUTHOR]

Purpose: Recent numerical and empirical results proved that high permittivity materials (HPM) used in pads placed near the subject or directly integrated with coils can increase the SNR and reduce the specific absorption rate (SAR) in MRI. In this paper, we propose an analytical investigation of the effect on the magnetic field distribution of a layer of HPM surrounding an anatomy‐mimicking cylindrical sample. Methods: The study is based on a reformulation of the Mie scattering for cylindrical geometry, following an approach recently introduced for spherical samples. The total field in each medium is decomposed in terms of inward and outward electromagnetic waves, and the fields are expressed as series of cylindrical harmonics, whose coefficients can be interpreted as classical reflection and transmission coefficients. Results: Our new formulation allows a quantitative evaluation of the effect of the HPM layer for varying permittivity and thickness, and it provides an intuitive understanding of such effect in terms of propagation and scattering of the RF field. Conclusion: We show how HPM can filter out the modes that only contribute to the noise or RF power deposition, resulting in higher SNR or lower SAR, respectively. Our proposed framework provides physical insight on how to properly design HPM for MRI applications. [ABSTRACT FROM AUTHOR]

Conjugated polymer (CP) based microspheres of very high definition and outstanding photonic and luminescent properties are prepared by a technique based on slow solvent‐controlled diffusion into micelles formed by the surfactant cetyl(trimethyl)ammonium bromide (CTAB). Poly[(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl)‐alt‐(benzo[2,1,3]thiadiazol‐4,8‐diyl)] (F8BT) and mixtures of F8BT with poly[2‐methoxy‐5‐(2'‐ethylhexyloxy)‐1,4‐phenylene vinylene (MEH‐PPV) are used for this purpose. Microspheres with diameters between 1 and 10 µm are obtained and structural characterization by AFM and SEM demonstrate good sphericity and low surface roughness. Correspondingly, spontaneous emission of the spheres exhibits Mie resonances of high quality factor (Q > 1800), appropriately reproduced employing standard Mie theory. Upon pumping the microspheres with a pulsed Nd:YAG laser operating at 355 nm lasing at low threshold fluences (≈ 4 µJ cm−2) is obtained with instrumentally limited linewidths corresponding to Q > 18000. Lasing in microspheres composed of blends of both CPs coupled by Förster resonant energy transfer (FRET), on the other hand, is observed at extremely low threshold fluences down to ≈ 0.5 µJ cm−2. Spherical structures based on appropriate blends of CPs are therefore promising candidates in the search for low‐threshold organic microlasers excited by light‐emitting diodes or diode lasers or for ultrasensitive optical sensing. [ABSTRACT FROM AUTHOR]

Accurate marine wind detection under all-weather conditions is crucial for maritime activities. The joint detection of lidar and radar is supposed to be a potential way to carry out the all-weather sensing of wind. However, their performance analysis has not been well studied, particularly in the far sea area, where the wind-tracing particles are quite different from those inland. Based on the particle distributions above the sea surface under different weather conditions, this study investigated the scattering and attenuation effects of lidar and radar waves in open sea areas with the Mie theory and T-matrix method. Then, the maximum detection range and velocity accuracies of lidar/radar were comprehensively analyzed based on detection principles to optimize the combination of lidar and radar. According to the simulation results, it was difficult to maintain the detection capability of a single lidar/radar under all-weather conditions, and 1.55 μ m lidar and W-band radar presented a promising joint detection scheme, as they exhibited optimal weather adaptability in clear sky and precipitation conditions, respectively. [ABSTRACT FROM AUTHOR]

Radiative cooling textiles hold promise for achieving personal thermal comfort under increasing global temperature. However, urban areas have heat island effects that largely diminish the effectiveness of cooling textiles as wearable fabrics because they absorb emitted radiation from the ground and nearby buildings. We developed a mid-infrared spectrally selective hierarchical fabric (SSHF) with emissivity greatly dominant in the atmospheric transmission window through molecular design, minimizing the net heat gain from the surroundings. The SSHF features a high solar spectrum reflectivity of 0.97 owing to strong Mie scattering from the nano-micro hybrid fibrous structure. The SSHF is 2.3°C cooler than a solar-reflecting broadband emitter when placed vertically in simulated outdoor urban scenarios during the day and also has excellent wearable properties. [ABSTRACT FROM AUTHOR]

Optical nonreciprocity is manifested as a difference in the transmission of light for the opposite directions of excitation. Nonreciprocal optics is traditionally realized with relatively bulky components such as optical isolators based on the Faraday rotation, hindering the miniaturization and integration of optical systems. Here we demonstrate free-space nonreciprocal transmission through a metasurface comprised of a two-dimensional array of nanoresonators made of silicon hybridized with vanadium dioxide (VO2). This effect arises from the magneto-electric coupling between Mie modes supported by the resonator. Nonreciprocal response of the nanoresonators occurs without the need for external bias; instead, reciprocity is broken by the incident light triggering the VO2 phase transition for only one direction of incidence. Nonreciprocal transmission is broadband covering over 100 nm in the telecommunication range in the vicinity of λ = 1.5 µm. Each nanoresonator unit cell occupies only ~0.1 λ3 in volume, with the metasurface thickness measuring about half-a-micron. Our self-biased nanoresonators exhibit nonreciprocity down to very low levels of intensity on the order of 150 W/cm2 or a µW per nanoresonator. We estimate picosecond-scale transmission fall times and sub-microsecond scale transmission rise. Our demonstration brings low-power, broadband and bias-free optical nonreciprocity to the nanoscale. Here the authors develop a subwavelength nonreciprocal optical component harnessing the effect is thermal phase transition of VO2 boosted by the Mie resonant response of the dielectric meta-surface. [ABSTRACT FROM AUTHOR]

We report a structure of silicon eccentric shell particles array, fabricated by the SiO2 particles monolayer array assisted deposition of amorphous Si, for high-efficiency light confinement. The SiO2 particles monolayer array is tailored to regulate its interparticle distance, followed by silicon film deposition to obtain silicon eccentric shell arrays with positive and negative off-center distance e. We studied the Mie resonances of silicon solid sphere, concentric shell, eccentric shell and observed that the eccentric shell with positive off-center e supports superior light confinement because of the enhanced Mie magnetic resonances. Spectroscopic measurements and finite difference time domain simulations were conducted to examine the optical performance of the eccentric shell particles array. Results show that the Mie magnetic resonance wavelength can be easily regulated by the size of the inner void of the silicon shell to realize tunable enhanced light confinement. It was found silicon shell with D = 460/520 nm offered high enhanced light absorption efficiency at wavelength of λ = 830 nm, almost beyond the bandgap of the amorphous silicon. [ABSTRACT FROM AUTHOR]

We present a goniometer designed for capturing spectral and angular-resolved data from scattering and absorbing media. The experimental apparatus is complemented by a comprehensive Monte Carlo simulation, meticulously replicating the radiative transport processes within the instrument's optical components and simulating scattering and absorption across arbitrary volumes. Consequently, we were able to construct a precise digital replica, or "twin", of the experimental setup. This digital counterpart enabled us to tackle the inverse problem of deducing optical parameters such as absorption and scattering coefficients, along with the scattering anisotropy factor from measurements. We achieved this by fitting Monte Carlo simulations to our goniometric measurements using a Levenberg–Marquardt algorithm. Validation of our approach was performed using polystyrene particles, characterized by Mie scattering, supplemented by a theoretical analysis of algorithmic convergence. Ultimately, we demonstrate strong agreement between optical parameters derived using our novel methodology and those obtained via established measurement protocols. [ABSTRACT FROM AUTHOR]

Stress whitening is a milky-white appearance occurring in a variety of polymers during the mechanical loading and plastic deformation. The current research examines the pattern of stress whitening occurrence including the onset and the progress in polypropylene by conducting gray scale, blush measurements and microscopic studies during tensile tests. Histograms of digital image processing in deformed zone showed that the distribution of the gray-level data points changed from a (a) narrow to (b) an extended with tail distribution, followed by (c) growth of a second peak with time which indicates that stress whitening intensification occurs gradually and generally through the deformation region. It means that whitening consists of whitening intensity enhancement and spread of whitened zone. Microscopic evaluations also showed that at regions close to the neck, the spherulitic structures are ruined and changed to fibrillar structures by deformation development. As a result, the origin of stress whitening from two distinct resources, (a) defects including micro-voids and voids such as craze, semi-craze or crack structures (occurring close to and far from the neck areas) and (b) orientations of fibrillar structures (occurring in the neck area), were considered completely. Moreover, it was shown that increasing the strain rate in tensile test leads to formation of more visible whitened area within the plastically deformed zone. This is the consequence of further growth of micro-voids at higher strain rates. At last, the agreement between these observations and the Mie scattering concept is discussed. [ABSTRACT FROM AUTHOR]

The combustor employed in small and medium-sized turboshaft engines is characterized by a small flame tube height and a large distance between adjacent burners, rendering it challenging to ignition. Moreover, the process of spray ignition exhibits complexity and needs further investigation. This study will delve into the performances of spray atomization and spark ignition within an annular combustor. Our objective is to thoroughly elucidate the interplay among atomization characteristics and flame propagation, seeking to shed some light on the fundamental mechanisms underlying flame dynamics from the perspective of timescales during the light-round processes. Planar Mie scattering and high-speed imaging technologies are employed to capture droplet distribution and time-resolved flame images, respectively. We have developed an algorithm capable of precisely tracking the flame front, enabling us to map out the trajectories of flame propagation. An analysis of transient flames reveals that the movement of leading points can be elucidated by the characteristics of the flow field and the distribution of the spray. It is demonstrated that the velocity of the flame front is affected by factors such as the pressure drop, equivalence ratio, and the distance between adjacent burners. Through an analysis of numerous spark events, this work identifies three distinctive flame propagation patterns: swirling-entrainment, archlike-entrainment, and another archlike-entrainment pattern. It is noted that these patterns exhibit variations by alterations in pressure drop and equivalence ratio. [ABSTRACT FROM AUTHOR]

We discuss the possibility of self-hybridisation in high-index dielectric nanoparticles, where Mie modes of electric or magnetic type can couple to the interband transitions of the material, leading to spectral anticrossings. Starting with an idealised system described by moderately high constant permittivity with a narrow Lorentzian, in which self-hybridisation is visible for both plane-wave and electron-beam excitation, we embark on a quest for realistic systems where this effect should be visible. We explore a variety of spherical particles made of traditional semiconductors such as Si, GaAs, and GaP. With the effect hardly discernible, we identify two major causes hindering observation of self-hybridisation: the very broad spectral fingerprints of interband transitions in most candidate materials, and the significant overlap between electric and magnetic Mie modes in nanospheres. We thus depart from the spherical shape, and show that interband–Mie hybridisation is indeed feasible in the example of GaAs cylinders, even with a simple plane-wave source. This so-far unreported kind of polariton has to be considered when interpreting experimental spectra of Mie-resonant nanoparticles and assigning modal characters to specific features. On the other hand, it has the potential to be useful for the characterisation of the optical properties of dielectric materials, through control of the hybridisation strength via nanoparticle size and shape, and for applications that exploit Mie resonances in metamaterials, highly-directional antennas, or photovoltaics. [ABSTRACT FROM AUTHOR]

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