Dominant Wavelength Research Articles

Nanoscale stereometric analysis of polycrystalline PDI8-CN2 thin films on hydrogen-terminated silicon (H-Si) for enhanced surface functionality

In this study, polycrystalline thin films of PDI8-CN2 deposited on hydrogen-terminated silicon (H-Si) were thoroughly examined using atomic force microscopy (AFM). The research focused on characterizing the surface micromorphology through advanced analyses, including contour line plots, Abbott-Firestone curves, furrow depth analysis, texture direction evaluation, power spectral density (PSD), frequency spectrum, fractal analysis, and motif analysis. The contour line plots revealed significant height variations, while the Abbott-Firestone curve mapped the relative proportions of elevated and recessed areas. Furrow depth analysis showed prominent valleys with a mean depth of 7.03 nm. Texture direction analysis indicated an isotropy of 32 %, confirming moderate surface directionality. The PSD analysis revealed a dominant wavelength of 2834 nm, aligning with the roughness features observed. Fractal analysis demonstrated a self-similar surface with a fractal dimension of 2.45. Motif analysis indicated significant contributions of peaks and pits to surface roughness, with peaks having the largest mean area of 0.220 μm2. Statistical parameters, including a root mean square height of 5.02 nm and maximum height of 42.4 nm, confirmed the roughness and height variation. Integrating of these techniques offers a detailed understanding of surface topography, which is essential for optimizing functional properties in material applications. The results provide insight into the structural organization of PDI8-CN2 films, which is important for optimizing their use in organic electronics.

Investigation of tetrazole- and bistetrazole-based lithium salts as colorants in environmentally friendly pyrotechnics

ABSTRACT Due to the harmful effects of chlorinated combustion products and strontium in currently used red-burning pyrotechnics on human health and the environment, new substitutes have to be found. A promising alternative could be using lithium-salts. While it is a literature-known problem that the generation of a lithium-based red flame color is a challenging task due to the diverse requirements of the Li(0) color species, a promising alternative could be using lithium-heterocycle salts. In this context, nitrogen-rich lithium tetrazole and bistetrazole salts, namely, lithium tetrazolate, lithium 5-aminotetrazolate, dilithium 5,5’-bistetrazolate dihydrate and dilithium 5,5’-bis(tetrazolate-1-oxide) have been investigated as potential replacements. To evaluate the performance of the salts a variety of mixtures were prepared and their pyrotechnic parameters were analyzed. Furthermore, application-specific pyrotechnic clusters and parachute flares were produced and these were also tested for burning time, dominant wavelength, spectral purity and luminous intensity. Observations on the use of lithiated nitrogen-rich salts in pyrotechnic mixtures showed a red color impression, indicating the potential of these mixtures. Further research opportunities can be pursued by refining nitrogen-rich compounds.

Physically Structured Variational Inference for Bayesian Full Waveform Inversion

AbstractFull waveform inversion (FWI) creates high resolution models of the Earth's subsurface structures from seismic waveform data. Due to the non‐linearity and non‐uniqueness of FWI problems, finding globally best‐fitting model solutions is not necessarily desirable since they fit noise as well as the desired signal in data. Bayesian FWI calculates a so‐called posterior probability distribution function, which describes all possible model solutions and their uncertainties. In this paper, we solve Bayesian FWI using variational inference, and propose a new methodology called physically structured variational inference, in which a physics‐based structure is imposed on the variational distribution. In a simple example motivated by prior information from imaging inverse problems, we include parameter correlations between pairs of spatial locations within a dominant wavelength of each other, and set other correlations to zero. This makes the method far more efficient compared to other variational methods in terms of both memory requirements and computation, at the cost of some loss of generality in the solution found. We demonstrate the proposed method with a 2D acoustic FWI scenario, and compare the results with those obtained using other methods. This verifies that the method can produce accurate statistical information about the posterior distribution with hugely improved efficiency (in our FWI example, 1 order of magnitude reduction in computation). We further demonstrate that despite the possible reduction in generality of the solution, the posterior uncertainties can be used to solve post‐inversion interrogation problems connected to estimating volumes of subsurface reservoirs and of stored , with minimal bias, creating a highly efficient FWI‐based decision‐making workflow.

Assessment of luminescent features on Sm3+ ions doped LiF assimilated lead-free borate glasses for visible photonic and optoelectronic applications

The distinctive set containing Sm3+ ions doped LiF incorporated Alkaline borate glasses have been synthesised via the melt quenching practice. 59B2O3+20LiF+(20–X)CaCO3+XBaCO3 +1Sm2O3 (where X = 5, 10, 15, 20 wt%) is the composition used for the glass preparation. The effect of samarium ions concentration dependency on the absorption and emission of barium and calcium oxide has been studied through several spectroscopic studies. The current set of glasses is ionic, determined by the bonding value. The hypersensitive absorption transition is found in the visible region of the absorption spectra, and the transition from 6H5/2 to 6P3/2 shows the highest oscillator strength of 14.87 × 10−6. The intensity parameters are denoted by Ωλ (where λ = 2,4,6) are assessed and discussed. The results indicate that Ω4 is higher when compared to the other two parameters. The lower Ω2 values further ensure the ionic nature of the glass samples. Moreover, the intensity parameters are utilised to predict some radiative properties for the lasing potential evaluation, which includes cross-sections of emission (σPE), probability of radiative transition (A), and experimental and radiative lifetime (τexp and τR). The decay profile was monitored for the 4G5/2 state, and consistently non-exponential behaviour was observed in all the glasses. Through the CIE colour chromaticity analysis, the CCT (colour-correlated temperature), dominant wavelength, colour, and purity of the emitted light have been evaluated. Concerning all aspects, the glass with 20 wt% of BaCO3 is found to be fit for photonic and optoelectronic applications.

Study on Synergistic Radiation Yellow Light of Strontium Nitrate/Barium Nitrate-Based Illuminant

ABSTRACT In order to change the problem of a single yellow light color emitted by sodium salt illuminant. Based on the principle of color-light mixing and the mechanism of synergistic radiation of double-dyeing flame agents, four groups of strontium nitrate/barium nitrate-based yellow light illuminant formulations with different ratios were designed, which were calculated and comparatively analyzed by REAL and MATLAB software through experiments. From the experimental results, it can be seen that the virtual main wavelength of strontium nitrate/barium nitrate-based yellow light illuminant was adjusted in the range of 579 nm-591 nm, and the color ranged from light yellow to golden yellow, among which the best formulation was strontium nitrate/barium nitrate/magnesium/worm gum/polyvinyl chloride with the ratio of 50.25/16.25/13.5/2.5/17.5. The oxygen balance of this formulation was −0.130 g-g-1, and the combustion temperature was 2790.88 K. The color light emitters were Sr, SrO, SrOH, SrCl, Ba, BaO, BaOH, BaCl, the color coordinates were (0.5256, 0.3988), the virtual dominant wavelength was 591 nm, the color purity was 0.79, and the luminescence intensity was 247,893.18 cd, and the combustion time was 6.8s.

SPECTROKINETIC INVESTIGATION OF THE PHOTOCHROMIC SYSTEM UNDER CONTINUOUS UV IRRADIANCE USING REFLECTANCE VS. TIME CURVES

The photochromic properties of the dye 5-chloro-1,3,3-trimethylspiro[indoline-2,3'-[3H] naphtho[2,1-b] [1,4]- oxazine] were investigated by exposing it to continuous monochromatic irradiation using 360 nm ultraviolet irradiation using photochromic prints at 293.15  2 K; it undergoes a photocoloration and photodecoloration state, thus following the dynamics of a photochromic cycle of growth and decay phase, respectively. Even if the isolated photo isomeric form of the photochromic dye structure is unavailable, one can quantitatively analyse the photo-induced kinetics of photochromic systems using the raw reflectance data. The quantum colour yield is represented by colour span values [K/S] obtained by converting reflectance data to Kubelka- Munk values. The dynamics of the photoreaction in a photochromic system can be examined by analysing the constants for the rate of colouration and decolouration caused by light. By employing first-order kinetics, the dependent dominant wavelength [max] can be determined by fitting the raw data obtained as a change in reflectance values from the FOTOCHROM3 spectrophotometer. The relationship between the colour span values and the concentration of the photochromic dye employed in the photochromic prints is linear.

Influence of calcination temperature on the 3D nanoscale topography of LaMnO3 thin films: A comprehensive surface analysis

In this paper, we present a comprehensive study on the 3D nanoscale topography of LaMnO3 thin films, focusing on the influence of calcination temperature on surface morphology. The study reveals significant structural, chemical, and morphological changes as a function of the calcination temperature. XRD analysis confirmed the formation of the orthorhombic LaMnO3 structure at 700 °C, 750 °C, and 800 °C, with increasing unit cell volume and crystallite size observed at higher temperatures. FTIR spectra identified characteristic functional groups associated with molecular vibrations, indicating the perovskite structure. SEM imaging showed grain growth with temperature, while EDS analysis confirmed compound formation and substrate interactions. AFM analysis revealed increased surface roughness with temperature, attributed to nucleation and crystal growth. Morphological and microtextural analyses further detailed changes in surface features, peaks, valleys, and voids. Fractal characterization highlighted variations in surface texture with temperature, with a decrease in dominant wavelength indicating changes in microtexture complexity. Overall, the findings provide insights into the temperature-dependent properties of LaMnO3 thin films, essential for optimizing growth conditions and understanding their potential applications in various fields.

Dynamic swarms regulate the morphology and distribution of soft membrane domains.

We study the dynamic structure of lipid domain inclusions embedded within a phase-separated reconstituted lipid bilayer in contact with a swarming flow of gliding filamentous actin. Passive circular domains transition into highly deformed morphologies that continuously elongate, rotate, and pinch off into smaller fragments, leading to a dynamic steady state with ≈23× speedup in the relaxation of the intermediate scattering function compared with passive membrane domains driven by purely thermal forces. To corroborate experimental results, we develop a phase-field model of the lipid domains with two-way coupling to the Toner-Tu equations. We report phase domains that become entrained in the chaotic eddy patterns, with oscillating waves of domains that correlate with the dominant wavelengths of the Toner-Tu flow fields.

Mechanism of rail corrugation formation on metro curves with a type of floating-slab track

ABSTRACT A steel spring floating-slab track (SSFST) capable of mitigating railway-induced vibrations has been widely used in a metro line in Beijing. In sharp curves with radii of less than 500 m, severe corrugation with wavelengths of about 125–200 mm and passing frequencies of 70–80 Hz occurred on low rails. Field measurements and numerical simulations were used to investigate the cause of the corrugation. The results show that the wavelength of corrugation is related to the speed of the vehicle and the corrugation passing frequency is a fixed frequency. The formation of the rail corrugation in the sharp curves does not depend on the torsional and bending resonances of wheelsets and P2 resonance. The wheel–rail vertical fluctuating force at frequencies of 67–75 Hz arises easily under a broadband excitation of the rail irregularity due to the vertical bending of the rail and the floating slab relative to the subgrade. The numerical simulations show that the corrugation with dominant wavelengths of 160–200 mm initiates when the vehicle passes over the irregularity. The simulation results are consistent with the field test results. The corrugation occurs on SSFST as a result of the vertical bending of the entire track, driven by a wavelength-fixing mechanism.

Electrodynamic properties of a rectangular waveguide with a dielectric plate located in the center of its wide wall

A rectangular waveguide with a dielectric plate located in the E-plane is the basic element of devices for microwave heat treatment of sheet materials. In this regard, it is relevant to study the processes of propagation and transformation of electromagnetic waves in such a system. The purpose of the work is to study the influence of the transformation of the electromagnetic field in the air medium of a rectangular waveguide in the zone of propagation of the slow wave H10 on the distribution of electric field energy in the dominant wavelength range and determining the wavelength, at which its maximum value is reached. The range properties of the intrinsic electrodynamic parameters and the field structure of a rectangular waveguide with a dielectric plate located in the E-plane in the middle of its wide wall have been studied. The wavelength at which the maximum energy level of the electric field in the dielectric plate is achieved is determined. The results obtained can be used in the design of microwave heating devices for dielectric materials.

60‐5: Late‐News Paper: External Quantum Efficiency of All InGaN Polychromic MicroLEDs

This paper reports on the performance results including radiance, dominant wavelength, and forward voltage of monolithic MicroLEDs that can emit red, green, and blue light simultaneously and are thus described as polychromic. Further, flip chip devices have been fabricated to facilitate absolute EQE external quantum efficiency (EQE) measurements. The peak EQE for a 20 × 17 µm device are 2.0 % in red, 14.2% in green, and 17.5% in blue.

Illuminating Life Sciences: A Biophysical Guide to the Use of Chromatic and White Light Sources in Photobiology

With the increasing availability of LEDs, researchers in photobiology have easier access to customized light sources. However, the abundance of different light sources poses new challenges for the correct characterization of existing light conditions. The photobiological effect of a light source depends mainly on the number of photons involved and the spectral composition. However, light sources are mainly described by parameters such as radiant flux, dominant or peak wavelength, and correlated color temperature (CCT). Therefore, in this work, chromatic and white light sources were measured for their spectral composition, various characterization parameters were determined, and the resulting photon flux densities were calculated, focusing on dominant versus peak wavelength for chromatic LEDs and the CCT for white LEDs and fluorescent tubes. The use of the dominant wavelength is inappropriate as it is partly outside the actual spectral range. It was also shown that white light sources with the same CCT have significantly different spectral compositions and, therefore, may have different photobiological effects. The results of this work should serve as a basis for life scientists to better compare light sources, to correctly interpret existing parameters, and to describe light conditions in a standardized and comparable way.

Experimental Analysis of the Light Wavelength’s Impact on the Performance of a Silicon Solar Cell

The main aim of this article is to analyse the Si solar cell’s behaviour when it is exposed to light of different colours. An experimental work, with 100 experimental tests, was carried out, using an RGB LED. In order to obtain better fitting of the characteristic curves’ results, we used a novel discrete model, d1MxP. The obtained results showed that all experimental points of the tests were inside the two triangles that connected the three theoretical primary colours and the three experimental primary colours in the chromaticity diagram. With this diagram, the colour purity could be determined, which presented values between 20% and 60%. The primary colours of the three different LEDs of the light source presented a dominant wavelength that corresponded to the peak wavelengths of the light source spectrum, which showed high purity. However, the obtained results show that mixing colours may not lead to an increase in the cell’s output power. Additionally, an increase in the cell’s temperature was observed, due to the surplus absorbed energy, which was converted into heat, being one of the causes of the cell’s efficiency reduction.

Experimental and theoretical analysis of finely bedded porous rock models with internal cracks

The behavior of ultrasonic waves in synthetic rocks consisting of alternating layers of sand-based (porous and permeable) and acrylic (unporous) materials is investigated. Two synthetic layered media are created, one without cracks and the other with parallel cracks in one of the layers, to increase anisotropy and simulate a heterogeneous transversely isotropic medium with a vertical axis of symmetry. Microcomputed tomography is used to obtain images of the samples, which indicate that there are no bubbles present and that the layers are well connected without any gaps or breaks. The experiment uses ultrasonic measurements to determine the propagation of P and S waves, with transducers at frequencies of 100 kHz, 500 kHz, and 1 MHz for traveltime and waveform measurements. These three sources are chosen to verify the effective behavior of the samples, which depends on the relationship between the dominant wavelength of investigation and the layer thickness ([Formula: see text]). The measured velocities are compared with theoretical models based on Backus, Kennett (traditional models), and Backus (modified for cracked media by Schoenberg and Muir’s theory). The main finding is that the cracked medium exhibits at least twice as large a difference in behavior for P- and S-wave vertical velocities as a function of the number of layers compared with the uncracked medium.

Water Colour Changes in High-Elevation Alpine Lakes during 2017–2022: A Case Study of the Upper Orco Valley Catchment

The water resource is severely compromised by climate change, and its availability and quality can no longer be taken for granted, even in places considered pristine, such as mountains. In this study, we evaluated the water colour variability of three artificial mountain lakes located in a relatively small basin (Western Italian Alps) at high elevations, and related this variability to the local climate conditions of the hydrological basin to which they belong. We estimated the dominant wavelength (DW) of lake water from Sentinel-2 acquisitions for the period 2017–2022, performing a chromaticity analysis. We correlated DW with climatic parameters recorded by two automated weather stations. Average DW varies from 497 nm of Serrù Lake and Agnel Lake to 512 nm of Lake Ceresole, where DW varies seasonally (variation of 75–100 nm in one year). During April–July, the DW of Lake Ceresole is significative correlated with air temperatures and snow cover (−0.8 and +0.8, respectively). During August–October, the relationship with temperature decreases to −0.5, and a correlation of 0.5 with the amount of rainfall appears. This work shows that mountain lake waters can exhibit variable quality (expressed here by water colour) in response to meteorological and hydrological conditions and events.

True‐Red InGaN Light‐Emitting Diodes for Display Applications

Red InGaN has attracted much attention recently for micro‐light‐emitting diode (microLED) display applications. However, the consequences of spectral broadening are often overlooked and many of the published spectra do not meet display gamut requirements. Herein, maximizing the red InGaN radiance with a spectrum capable of meeting the digital cinema initiatives‐protocol 3 standard (dominant wavelength of ≈615 nm) is focused on. The maximum radiance for LEDs meeting said requirement is obtained at 20 A cm−2 and corresponds to 4% wall‐plug efficiency (WPE) in large‐area encapsulated devices. The WPE can be increased to 12.5% using epitaxy of lower In concentration driven at 2 A cm−2. Also, data for microLEDs fabricated from similar red InGaN epitaxy are reported. No size dependence of the internal quantum efficiency or spectra is observed down to the smallest sizes studied (≈2 μm). Herein, expertise with red InGaN and nitride tunnel junctions is further leveraged to demonstrate polychromatic microLEDs with independent control of red, green, and blue emission within single pixels of 9 × 12 μm dimensions. These devices are grown in a single growth run on the same sapphire substrate wafer using methods proven in high‐volume epitaxy manufacturing.

Photonic Interpenetrating Polymer Network Fibers Comprising Intertwined Solid-State Cholesteric Liquid Crystal and Polyelectrolyte Networks for Sensor Applications.

Uniform-sized photonic interpenetrating polymer network (IPN) fibers comprising intertwined solid-state cholesteric liquid crystal (CLCsolid) and anionic poly(acrylic acid) (PAA) or cationic poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) networks (photonic IPNPAA or IPNPDMAEMA fibers) were developed for sensor applications. IPNPAA or IPNPDMAEMA fibers with a perfect photonic structure were fabricated inside Teflon tube templates without any treatments for realizing a planar orientation in those fibers. The dominant wavelength of the photonic color from a photograph taken with a cellular phone was used to measure the photonic color change. Photonic IPNPAA fibers treated with KOH (IPNKOH fibers) were used for sensing humidity and divalent metal ions. The linear ranges for relative humidity and Ca2+ detection were 21-92% and 0.5-3.5 mM, and their limits of detection (LODs) were 7.86% and 0.07 mM, respectively. The photonic IPNPAA (or IPNPDMAEMA) fiber immobilized with urease (IPNPAA-urease) (or glucose oxidase (IPNPDMAEMA-GOx)) was used for urea (or glucose) biosensor application. The photonic IPNPAA-urease (or IPNPDMAEMA-GOx) fiber was red-shifted in response to urea (or glucose) in the linear range of 10-60 mM (or 2-16 mM) with an LOD of 2.54 mM (or 0.76 mM). These photonic IPN fibers are promising because of their easy fabrication and miniaturization, battery-free device, cost-effectiveness, and visual detection without using sophisticated analytical instruments. The developed photonic IPN fibers provide new possibilities for the widespread use of photonic sensors in cutting-edge wearable technology and beyond.

Recyclable CS/r‐GO Polymer Nanocomposites: Green Synthesis and Characterizations

The study herein is directed toward the tuning of various properties of recyclable and biocompatible polymer: chitosan (CS) via incorporating the variable wt% of r‐GO in the polymer. The CS/r‐GO polymer nanocomposites (PNCs) are prepared in the form of free‐standing film by solution mixing and casting technique. To search the potential applications, the prepared PNCs are characterized in terms of structural, photoluminescence (PL), surface morphology, optical, and Raman spectra. The crystalline size and microstrain both are enhanced with rise in wt% of r‐GO nanofiller. Raman spectra confirm that as the wt% of r‐GO increases, there is a minor shift toward a smaller wavenumber in the locations of the D, G, and 2D bands, while the intensity ratios ) increase. Field‐emission scanning electron microscopy results are capable of offering details regarding the surface quality for the interface purposes. The characteristic peaks and their broadening in PL spectra, chromaticity coordinates, dominant wavelength, and correlated color temperature are altered with variation of r‐GO wt.%. The optical bandgap, refractive index, and Urbach energy are found to tune with varying the nanofiller wt.%. These results suggest that CS/r‐GO PNC may be the potential candidate for possible application in fabricating the tunable optoelectronic devices.

Research on the Terrain Characteristics of Changbai Mountain and Their Impact on Precipitation and Wind Distribution

The terrain of Changbai Mountain has great influence on the distribution of atmospheric flows and the occurrence and development of precipitation. However, quantitative studies on the real terrain characteristics and the terrain effect on precipitation distribution in this region are scant at present. This study quantitatively analyzes the regional characteristic of topographic perturbations and the relationship between terrain, wind, and precipitation in Changbai Mountain region by using a spectral analysis of the two-dimensional discrete cosine transform. Three domains with relatively heavy summer precipitation are selected as the study region. The results indicate that the overall terrain of the Changbai Mountain region exhibits anisotropic characteristics. The terrain spectra of domain B are less than those of domains A and C across the whole wavelength (λ) bands, indicating that the large-scale topographic perturbations of domain B are relatively weak. The largest topographic spectral peak of domain C shows the most pronounced undulation of terrain among the three domains. The dominant wavelengths of terrain height variance for domains A and C, both close to the respective maximum wavelengths, indicate more prominent large-scale topographic perturbations. For domain A, the variation of the precipitation spectra is consistent with that of the wind spectra at the wavelength bands of λ < 390 km, showing a high correlation between wind field and the occurrence of rainfall. The inverse relationship at larger wavelengths indicates that multiple factors contribute to the occurrence of rainfall. For domain B, there is consistency in the fluctuations of terrain spectra, precipitation spectra, and wind spectra at the wavelength bands of λ < 278.3 km, implying that the smaller-scale terrain has an important effect on the occurrence of summer precipitation. For domain C, the variations of terrain spectra, precipitation spectra, and wind spectra are almost consistent across the whole wavelength bands, indicating that the large-scale terrain and minor terrain both play a crucial role in atmospheric uplift and the occurrence and development of summer rainfall.

Visual stimulus brightness influences the efficiency of attractant-baited traps for catching Drosophila suzukii Matsumura (Diptera: Drosophilidae).

Drosophila suzukii (Matsumura) is an exotic pest of economic importance that affects several soft-skinned fruits in Mexico. Previously, we found that yellow or yellow-green rectangular cards inside a transparent trap baited with attractants improved D. suzukii capture. In this study, we evaluated the influence of rectangular cards with different yellow shades inside a transparent multi-hole trap baited with apple cider vinegar (ACV) on D. suzukii capture in the field. Second, we tested whether ACV-baited traps with cards of other geometric shapes affected D. suzukii catches compared to traps with rectangular cards. Third, we evaluated the effects of commercial lures combined with a more efficient visual stimulus from previous experiments on trapping D. suzukii flies. We found that ACV-baited traps plus a yellow-shaded rectangle card with 67% reflectance at a 549.74 nm dominant wavelength captured more flies than ACV-baited traps with yellow rectangle cards with a higher reflectance. Overall, ACV-baited traps with rectangles and squares caught more flies than did ACV-baited traps without visual stimuli. The traps baited with SuzukiiLURE-Max, ACV and Z-Kinol plus yellow rectangles caught 57, 70 and 101% more flies, respectively, than the traps baited with the lure but without a visual stimulus.