Optical Quantities Research Articles

Evaluating the Effects of BSA-Coated Gold Nanorods on Cell Migration Potential and Inflammatory Mediators in Human Dermal Fibroblasts.

Albumin-coated gold nanoparticles display potential biomedical applications, including cancer research, infection treatment, and wound healing; however, elucidating their interaction with normal cells remains an area with limited exploration. In this study, gold nanorods (GNR) were prepared and coated with bovine serum albumin (BSA) to produce GNR-BSA. The functionalized nanoparticles were characterized based on their optical absorption spectra, morphology, surface charge, and quantity of attached protein. The interaction between GNR-BSA and BSA with normal cells was investigated using human dermal fibroblasts. The cytotoxicity test indicated cell viability between ~63-95% for GNR-BSA over concentrations from 30.0 to 0.47 μg/mL and ~85-98% for BSA over concentrations from 4.0 to 0.0625 mg/mL. The impact of the GNR-BSA and BSA on cell migration potential and wound healing was assessed using scratch assay, and the modulation of cytokine release was explored by quantifying a panel of cytokines using Multiplex technology. The results indicated that GNR-BSA, at 10 μg/mL, delayed the cell migration and wound healing 24 h post-treatment compared to the BSA or the control group with an average wound closure percentage of 6% and 16% at 6 and 24 h post-treatment, respectively. Multiplex analysis revealed that while GNR-BSA reduced the release of the pro-inflammatory marker IL-12 from the activated fibroblasts 24 h post-treatment, they significantly reduced the release of IL-8 (p < 0.001), and CCL2 (p < 0.01), which are crucial for the inflammation response, cell adhesion, proliferation, migration, and angiogenesis. Although GNR-BSA exhibited relatively high cell viability towards human dermal fibroblasts and promising therapeutic applications, toxicity aspects related to cell motility and migration must be considered.

DETERMINING THE DENSITY AND MOLAR MASS OF AIR IN A HOME EXPERIMENT

Formulation of the problem. Experimental research is an integral part of physics education. During distance learning, students can carry out hands-on experiments only at home. Modern smartphones, equipped with various sensors, offer significant capabilities for this purpose. The literature offers quite extensive descriptions of experiments aimed at determining mechanical, acoustic, and optical quantities using smartphones. At the same time, insufficient attention has been paid to determining gas parameters that can be measured using the pressure sensor embedded in smartphones. Therefore, the relevant task is to develop a methodology for experimenting to determine the density of air and its molar mass at home using a pressure sensor. Materials and methods. To achieve the objective of the study, we used the analysis of the curriculum of the course "General Physics for Bachelor of Engineering", a review of the methodological instructions for performing laboratory work in the section "Molecular Physics and Thermodynamics" of the physics course of technical universities, a review of the literature on the topic of the study, and an analysis of the results of student research on the dependence of air pressure on altitude. We also surveyed students about the possibility of conducting the research at home and their interest in conducting other experiments using a smartphone. Results. The methodology for determining the density and molar mass of air was developed based on the results of a study of the pressure-height dependence. It is shown that it is necessary to perform statistical processing of experimental data to estimate the sought quantities. The experimental results allowed us to obtain values of density and molar mass of air that show a good correlation with the tabulated values. Conclusions. Studying the pressure-altitude relationship using a smartphone and the PhyPhox application allows for fairly accurate calculations of air density and molar mass. According to the survey results, students responded positively to conducting home experiments using smartphones.

Tuning optical properties of palgraphyne under biaxial mechanical strain: A density functional theory investigation

Palgraphyne is a two-dimensional material of carbon atoms with sp2 and sp hybridization. The influence of the biaxial mechanical strain on its optical properties is studied based on density functional theory calculations. It is observed that palgraphyne exhibits anisotropic behavior for photons with parallel and perpendicular polarizations. The dielectric constant of palgraphyne is higher than graphene. It has been found that biaxial tensile and compressive strains lead to an increase and decrease in the dielectric constant, respectively. The absorption spectra of palgraphyne sheet across the infrared to ultraviolet regions suggest that it has the potential to be a valuable material for utilization as absorber. Additionally, the reflection and transmission constants indicate that the sheet displays high transparency specially in the ultraviolet region. The peaks of optical quantities including dielectric constant, absorption coefficient, optical coefficient, reflection and transmission constants are moved to lower and higher energies under tensile and compressive strains, respectively. The anticipated results could make palgraphyne a candidate for optoelectronic applications.

Mean force emission theory for classical bremsstrahlung in strongly coupled plasmas

This work presents mean force emission theory, which extends the classical theory of bremsstrahlung emission to strongly coupled plasmas. In the high-frequency limit, the theory reduces to solving for the electron trajectory during a binary collision, but where the electron–ion interactions occur through the potential of mean force. In the low-frequency limit, it uses an autocorrelation formalism that captures effects of multiple collisions and strongly correlated motion. The predictions are benchmarked by comparison with first-principles classical molecular dynamics simulations of a fully ionized hydrogen plasma in which all interactions are repulsive. The comparison shows good agreement up to Coulomb coupling strengths of Γ∼30. The theory improves upon traditional models by including strong coupling effects and systematically including the effect of multiple collisions. Furthermore, mean force emission theory provides evidence that the Drude correction factor commonly used in quantum calculations of optical quantities may not be adequate at strong coupling.

Planckian behavior of cuprates at the pseudogap critical point simulated via flat electron-boson spectral density

Planckian behavior has been recently observed in La1·76Sr0·24CuO4 at the pseudogap critical point. The Planckian behavior takes place in an intriguing quantum metallic state at a quantum critical point. Here, the Planckian behavior was simulated with an energy-independent (or flat) and weakly temperature-dependent electron-boson spectral density (EBSD) function by using a generalized Allen's (Shulga's) formula. We obtained various optical quantities from the flat EBSD function, such as the optical scattering rate, the optical effective mass, and the optical conductivity. These quantities are well fitted with the recently observed Planckian behavior. Fermi-liquid behavior was also simulated with an energy-linear and temperature-independent EBSD function. The EBSD functions agree well with the overall doping- and temperature-dependent trends of the EBSD function obtained from the optically measured spectra of cuprate systems, which can be crucial for understanding the microscopic electron-pairing mechanism for high-Tc superconductivity in cuprates.

DFT studies of 2D materials inspired by Lie algebras

Inspired by the root systems of Lie algebras of rank 2, we propose a mathematical method to engineer new 2D materials with double periodic structures tessellating the plane. Concretely, we investigate two geometries relaying on squares and hexagons exhibiting the D 4 × D 4 and D 6 × D 6 dihedral group invariances, respectively. Due to lack of empirical verifications of such double configurations, we provide a numerical investigation by help of the open source quantum espresso. Motivated by hybrid structures of the graphene, the silicene, and the germanene, we investigate two models involving the D 4 × D 4 and D 6 × D 6 dihedral symmetries which we refer to as Si4Ge4 and Si6C6 compounds, respectively. For simplicities, we study only the opto-electronic physical properties by applying an electromagnetic source propagating in linear and isotropic mediums. Among others, we find that such 2D materials exhibit metallic behaviors with certain optical features. Precisely, we compute and discuss the relavant optical quantities including the dielectric function, the absorption spectra, the refractive index, and the reflectivity. We believe that the Lie algebra inspiration of such 2D material studies, via density functional theory techniques, could open new roads to think about higher dimensional cases.

Study on sound transmission characteristics and positioning strategy of gas insulated transmission line shell

Gas insulated transmission line (GIL) is widely used for large-capacity power transmission in complex environment, and has the characteristics of long distance and totally enclosed structure. When the insulation fault occurs inside GIL, its metal shell structure makes it more difficult to monitor through optical, electrical and other physical quantities. Considering the rapidity and accuracy of positioning, the propagation of sound waves along the GIL sheath is a commonly used method in GIL on-site PD testing and running state online monitoring for fault positioning. This paper establishes a high-pressure GIL acoustic propagation simulation model based on pipe acoustics theory, analyzes the frequency dispersion and mode distribution of acoustic waves along the GIL shell, determines an appropriate fault location strategy based on the propagation velocity and attenuation of the selected acoustic wave mode, and carries out experiments to verify it. The results of the research show that the low order bending wave F(1,1) propagated along the GIL shell has good positioning characteristics, and the propagation velocity conforms to the dispersion curve distribution. By taking into account the attenuation and delay of the acoustic wave passing through epoxy insulators or expansion joints in the fault localization strategy, the localization accuracy can be improved by 60%. And this positioning strategy was verified to be effective in the GIL insulation fault localization test conducted in the field.

Investigating the optical translucency of Spectralon using BSSRDF measurements.

Translucent materials have the property of reflecting light beyond the illumination point due to subsurface light propagation in the material. These reflectance properties can be characterized using the bidirectional scattering-surface reflectance distribution function (BSSRDF), a radiometric quantity that is a function of spatial, angular, spectral, and polarization parameters. At very small scales, we have observed that Spectralon, a commercial material widely used as a diffuse reflectance calibration standard, can be regarded as translucent. This can generate measurement errors and limit Spectralon's reliability as a calibration artefact for instruments that measure optical quantities on very small surfaces. To characterize the translucent properties of Spectralon, we have measured its BSSRDF using an experimental setup based on a goniospectrophotometer with a spatial scanning system for detection. In the present study, we show that Spectralon cannot be considered an opaque material at small scales (below 1mm). For instrument measuring on small areas, Spectralon can be used for calibration only when the illumination area and the observation area differ by more than 1mm in radius.

Underwater Small Target Detection Based on YOLOX Combined with MobileViT and Double Coordinate Attention

The underwater imaging environment is complex, and the application of conventional target detection algorithms to the underwater environment has yet to provide satisfactory results. Therefore, underwater optical image target detection remains one of the most challenging tasks involved with neighborhood-based techniques in the field of computer vision. Small underwater targets, dispersion, and sources of distortion (such as sediment and particles) often render neighborhood-based techniques insufficient, as existing target detection algorithms primarily focus on improving detection accuracy and enhancing algorithm complexity and computing power. However, excessive extraction of deep-level features leads to the loss of small targets and decrease in detection accuracy. Moreover, most underwater optical image target detection is performed by underwater unmanned platforms, which have a high demand of algorithm lightweight requirements due to the limited computing power of the underwater unmanned platform with the mobile vision processing platform. In order to meet the lightweight requirements of the underwater unmanned platform without affecting the detection accuracy of the target, we propose an underwater target detection model based on mobile vision transformer (MobileViT) and YOLOX, and we design a new coordinate attention (CA) mechanism named a double CA (DCA) mechanism. This model utilizes MobileViT as the algorithm backbone network, improving the global feature extraction ability of the algorithm and reducing the amount of algorithm parameters. The double CA (DCA) mechanism can improve the extraction of shallow features as well as the detection accuracy, even for difficult targets, using a minimum of parameters. Research validated in the Underwater Robot Professional Contest 2020 (URPC2020) dataset revealed that this method has an average accuracy rate of 72.00%. In addition, YOLOX’s ability to compress the model parameters by 49.6% efficiently achieves a balance between underwater optical image detection accuracy and parameter quantity. Compared with the existing algorithm, the proposed algorithm can carry on the underwater unmanned platform better.

Extreme Refractive-, Diffractive- and Hybrid-Hyperchromats: Minimizing the Equivalent Abbe Number of a Two-Lens System

This work provides a comprehensive analysis of the maximum chromatic axial split of two-element hyperchromats, with the distance between the two lenses being a key variable. Purely refractive and diffractive systems are considered, as well as hybrid layouts combining refractive and diffractive elements. In order to achieve extreme chromatic axial splitting and accordingly a minimum equivalent Abbe number for lens combinations, a three-step procedure was used. In the first paraxial step, purely optical quantities such as focal lengths of the lenses, inter-lens distances and dispersion properties of the lenses were investigated. In the second step, which also takes place in the paraxial domain, additional geometric boundary conditions such as the radii, diameters and thicknesses of the lenses are taken into account. The results of this step serve as an input for the final optimization using optical design software, which derives practical solutions for minimum equivalent Abbe numbers with diffraction-limited image quality. As a significant result, the comparison with directly cemented lens doublets shows that the introduction of a distance between the elements allows for a much stronger chromatic decomposition for refractive, diffractive and also hybrid combinations. Quantitatively, the minimum equivalent Abbe number for refractive systems is reduced from 2.5 (without spacing) to 1.79 (with spacing). For hybrid combinations, a corresponding reduction from 0.4 to 0.29 is achieved.

NMPC-based visual path following control with variable perception horizon

AbstractFor greater autonomy of visual control-based solutions, especially applied to mobile robots, it is necessary to consider the existence of unevenness in the navigation surface, an intrinsic characteristic of several real applications. In general, depth information is essential for navigating three-dimensional environments and for the consistent parameter calibration of the visual models. This work proposes a new solution, including depth information in the visual path-following (VPF) problem, which allows the variation of the perception horizon at runtime while forcing the coupling between optical and geometric quantities. A new NMPC (nonlinear model predictive control) framework considering the addition of a new input to an original solution for the constrained VPF-NMPC allows the maintenance of low computational complexity. Experimental results in an outdoor environment with a medium-sized commercial robot demonstrate the correctness of the proposal.

Group refractive index via auto-differentiation and neural networks

In this article, using principles of automatic differentiation, we demonstrate a generic deep learning representation of group refractive index for photonic channel waveguides. It enables evaluation of group refractive indices in a split of second, without any traditional numerical calculations. Traditionally, the group refractive index is calculated by a repetition of the optical mode calculations via a parametric wavelength sweep of finite difference (or element) calculations. To the direct contrary, in this work, we show that the group refractive index can be quasi-instantaneously obtained from the auto-gradients of the neural networks that models the effective refractive index. We embed the wavelength dependence of the effective index in the deep learning model by applying the scaling property of the Maxwell’s equations and this eliminates the problems caused by the curse of dimensionality. This work portrays a very clear illustration on how physics-based derived optical quantities can be calculated instantly from the underlying deep learning models of the parent quantities using automatic differentiation.

An Aero-Optical Effect Analysis Method in Hypersonic Turbulence Based on Photon Monte Carlo Simulation

Aero-optical effects caused by hypersonic turbulence will affect the accuracy of optical sensors on aircraft. Traditional analysis methods, which do not consider absorption and scattering effects, cannot easily be used to completely describe the transmission process of light in hypersonic turbulence. In this paper, an aero-optical effect analysis method based on photon Monte Carlo simulation (MC-AOEA) was proposed to explain the distortion characteristics of aero-optical effects from the perspective of photon statistics. The energy distribution of photons in the transmission process was determined by taking a photon packet as a unit, and the microscopic statistics of the photon dissipation energy for all photon packets were calculated. The effectiveness of this method was verified by comparing the photon statistical parameters with the traditional optical distortion physical quantities. MC-AOEA was used to analyze the distortion of aero-optical effects at different altitudes and speeds. Additionally, the simulation results showed that, with the reduction in flight altitude and the enhancement of speed, the distortion of aero-optical effects was aggravated, and the energy loss was more serious, which provides a reference for the evaluation of aero-optical effect errors.

First-principles prediction of asymmetric electronic structures, optoelectronic features, and efficiency for Sb2S3, Tl2S, TlSbS2, and TlSb3S5 compounds

In this study, the density functional theory calculations were used to calculate the electronic structures and optical properties of binary and ternary antimony chalcogenide compounds Sb2S3, Tl2S, TlSbS2, and TlSb3S5. The band structures and density of states have shown that the asymmetric densities in Sb2S3, TlSbS2, and TlSb3S5 compounds are due to the presence of 5s states of antimony-Sb. This asymmetric density is affected by the increase in the energy of the 3p valence state of the S element. The fundamental bandgaps were calculated, which revealed a direct semiconductor character in the middle of the Brillouin zone for TlSb3S5, whereas Sb2S3, Tl2S, and TlSbS2 exhibited an indirect semiconductor behavior. In addition, the changes in various optical quantities as a function of wavelength were also calculated and discussed to determine the optoelectronic efficiency of the studied compounds.

Optical characterization of inhomogeneous thin films with randomly rough boundaries exhibiting wide intervals of spatial frequencies.

Results concerning the optical characterization of two inhomogeneous polymer-like thin films deposited by the plasma enhanced chemical vapor deposition onto silicon single crystal substrates are presented. One of these films is deposited onto a smooth silicon surface while the latter film is deposited on a randomly rough silicon surface with a wide interval of spatial frequencies. A combination of variable-angle spectroscopic ellipsometry and spectroscopic reflectometry applied at near-normal incidence are utilized for characterizing both the films. An inhomogeneity of the films is described by the method based on multiple-beam interference of light and method replacing inhomogeneous thin films by multilayer systems. Homogeneous transition layers between the films and substrates are considered. The Campi-Coriasso dispersion model is used to express spectral dependencies of the optical constants of the polymer-like films and transition layers. A combination of the scalar diffraction theory and Rayleigh-Rice theory is used to include boundary roughness into formulae for the optical quantities of the rough polymer-like film. Within the optical characterization, the spectral dependencies of the optical constants at the upper and lower boundaries of both the polymer-like films are determined together with their thickness values and profiles of the optical constants. Roughness parameters are determined for the rough film. The values of the roughness parameters are confirmed by atomic force microscopy. Moreover, the optical constants and thicknesses of both the transition layers are determined. A discussion of the achieved results for both the polymer-like films and transition layers is performed.

Optical transmission quality and radiation protection relevance of TeO2-ZnO-Yb2O3-ZnCl glass system

Tellurite glasses are known to present attributes which makes them attractive for optical and radiation shielding functions. This study presents the optical and γ-radiation absorption quantities of (89-x)TeO2 -xZnCl-10ZnO-Yb2O3 (for 0 ≤ x ≤ 30 mol. % in steps of 10 mol. % and coded as TZZCY1-TZZCY4 accordingly). The optical characteristics of the glasses were determined through the estimation and analysis of optical quantities such as the molar volume, molar refractivity, molar polarizability, reflection-loss, optical-transmission, metallization-criterion, static dielectric constant and the optical dielectric constant. The mass attenuation coefficient MAC of the glasses was estimated for energy E in the range 0.015≤E≤15 MeV through XCOM computation and photon transmission simulation by PHITS. The gamma ray shielding competence of the glasses was analysed through the computed mass attenuation coefficient, the linear attenuation coefficient, effective atomic number, mean free path, and half-value layer HVL. The molar refractivity, molar polarizability, reflection loss, static dielectric constant, and optical dielectric constant, all decline with increase in ZnCl2 content of the glasses while the optical transmission and metallization criterion increases. The addition and increase in the proportion of ZnCl2 compromised the photon-absorption ability of the TZZCY glasses although the optical transparency of the glasses was improved.

Influence of temperature and hydrostatic pressure on the nonlinear optical properties in a GaAs/GaAlAs Kratzer-Fues confined quantum well

The investigation of the comprehensive influence of temperature and hydrostatic pressure on the nonlinear optical absorption coefficients(OACs), optical rectification(OR), second harmonic generation(SHG) and third harmonic generation(THG) in a Kratzer-Fues confined quantum well(QW) is carried out by means of the effective-mass approximation and density matrix formalism. The findings indicate that the nonlinear optical properties(OACs, OR, SHG, THG) are significantly different in response to temperature and hydrostatic pressure. Simultaneously, we find that the effects of temperature and hydrostatic pressure on the nonlinear OACs, OR, SHG and THG in this system are more pronounced. So the magnitude and the red and blue shift in the position of the OACs, OR, SHG and THG can be adjusted by changing the strength of the temperature and hydrostatic pressure, thus promoting the development of the optical modulators and miscellaneous device applications based on the nonlinear properties. • The OACs, OR, SHG and THG in Kratzer-Fues QW are studied. • We obtain the energy eigenvalues and eigenfunctions via the fine difference method. • The effect of P and T on these important optical quantity are also studied. • Nanostructures possess considerably different behaviors under P and T.

Mechanical, optical, and gamma-attenuation properties of a newly developed tellurite glass system

ObjectiveThis study presents an experimental evaluation of the optical properties of a newly developed 75TeO2-5Na2O-(20-x)BaO-xTiO2 (with x = 0; 5; 10; 15) glass system. Moreover, we examine the mechanical and gamma attenuation features of the studied glasses. MethodThe glasses were prepared by the melt and rapid quench method; gamma attenuation coefficients were obtained through FLUKA simulations and XCOM computations; UV-Vis data were used to estimate the optical parameters of the glasses; while the mechanical quantities were estimated theoretically. ResultsThe optical, mechanical, and gamma radiation absorption quantities showed fluctuations as the chemical composition of the glasses changed. The refractive index changes from 2.35 to 2.43 while the optical bandgap and transmission declines from 3.20 eV and 72% to 2.88 eV and 70% respectively as the molar concentration of TiO2 changes from 0−15 mol%. The computed Young’s, bulk, shear, and longitudinal modulus increased from 210.31 to 256.53, 126 – 158.92, 91.90 – 111.33, and 249.11 – 307.35 GPa respectively for increasing TiO2 content. The calculated gamma radiation shielding parameters shielding effectiveness of the glasses narrowly trend in the order of TNB-Ti00 > TNB-Ti05 > TNB-Ti10 > TNB-Ti15. ConclusionCompared to conventional glass shields and shielding concrete, the present glasses are superior. The optical, mechanical, and shielding qualities of the investigated glass system reveal their huge potentials in optical and structural shielding applications in radiation facilities.

Inducing robustness and plausibility in deep learning optical 3D printer models.

Optical 3D printer models characterize multimaterial 3D printers by predicting optical or visual quantities from material arrangements or tonal values. Their accuracy and robustness to noisy training data are crucial for 3D printed appearance reproduction. In our recent paper [Opt. Express29, 615 (2021)10.1364/OE.410796], we have proposed a pure deep learning (PDL) optical model and a training strategy achieving high accuracy with a moderate number of training samples. Since the PDL model is essentially a black-box without considering any physical grounding, it is sensitive to outliers or noise of the training data and tends to create physically-implausible tonal-to-optical relationships. In this paper, we propose a methodology to narrow down the degrees-of-freedom of deep-learning based optical printer models by inducing physically plausible constraints and smoothness. Our methodology does not need any additional printed samples for training. We use this approach to introduce the robust plausible deep learning (RPDL) optical printer model enhancing robustness to erroneous and noisy training data as well as physical plausibility of the PDL model for selected tonal-to-optical monotonicity relationships. Our experiments on four state-of-the-art multimaterial 3D printers show that the RPDL model not only almost always corrects implausible tonal-to-optical relationships, but also ensures significantly smoother predictions, without sacrificing accuracy. On small training data, it even outperforms the PDL model in accuracy by up to 8% indicating a better generalization ability.

Active Opto-Magnetic Biosensing with Silicon Microring Resonators.

Integrated optical biosensors are gaining increasing attention for their exploitation in lab-on-chip platforms. The standard detection method is based on the measurement of the shift of some optical quantity induced by the immobilization of target molecules at the surface of an integrated optical element upon biomolecular recognition. However, this requires the acquisition of said quantity over the whole hybridization process, which can take hours, during which any external perturbation (e.g., temperature and mechanical instability) can seriously affect the measurement and contribute to a sizeable percentage of invalid tests. Here, we present a different assay concept, named Opto-Magnetic biosensing, allowing us to optically measure off-line (i.e., post hybridization) tiny variations of the effective refractive index seen by microring resonators upon immobilization of magnetic nanoparticles labelling target molecules. Bound magnetic nanoparticles are driven in oscillation by an external AC magnetic field and the corresponding modulation of the microring transfer function, due to the effective refractive index dependence on the position of the particles above the ring, is recorded using a lock-in technique. For a model system of DNA biomolecular recognition we reached a lowest detected concentration on the order of 10 m, and data analysis shows an expected effective refractive index variation limit of detection of RIU, in a measurement time of just a few seconds.