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It is known that rare-earth-based pyrochlore oxide may accommodate the well-defined two-in-two-out spin ice state with its tetrahedral unit. Low-energy excitation is argued to favor the highly concerned monopole state which attracts essential attention. However, such an excitation cannot be directly tracked and imaged using advanced characterizations, raising challenges to our understanding of the physics of monopoles. In this work, we propose an improved two-dimensional artificial spin ice structure on the Shastry–Sutherland lattice to restore the degeneracy of realistic pyrochlore systems. Such a structure avoids the deficiency of inequivalent nearest and next-nearest exchanges in the planar quadrate unit, which, however, is equivalent to the tetrahedral unit of realistic pyrochlore oxides. Therefore, this spin ice model restores state degeneracy that is lost in conventional planar artificial spin ice structures, representing an improved simulator of real spin ice systems. Our careful investigations of such improved structures reveal the rich physics of spin ice excitations, including the phase diagram, which allows different ordered phases and interesting critical phase transitions between spin ice phase I and phase II. Energy spectrum analysis suggests that restoration of state degeneracy substantially reduces monopole excitation energy, resulting in a striking monopole emergency at the critical point. Furthermore, the emergent spin dimer phase in this improved model allows high-density monopole excitations and exhibits high-correlated monopole fluid states. [ABSTRACT FROM AUTHOR]

Purpose: To investigate how well an implant stability quotient (ISQ) represents resonance frequency. Materials and Methods: Benchtop experiments on standardized samples that replicated a mandibular premolar site were conducted to correlate an ISQ value and a resonance frequency to synthetic bone density and an incremental insertion torque; then, a frequency spectrum analysis was performed to check the validity of the resonance frequency analysis (RFA). Brånemark Mk III implants (4 × 11.5 mm; Nobel Biocare) were placed in Sawbones test models of five different densities (40, 30, 40/20, 20, and 15 PCF). An incremental insertion torque was recorded during implant placement. To perform stability measurements, the test models were partially clamped in a vise (unclamped volume: 10 × 20 × 34 mm). A MulTipeg (Integration Diagnostics) was attached to the implants, and a Penguin (Integration Diagnostics) RFA measured ISQ. Simultaneously, the MulTipeg motion was monitored via a laser Doppler vibrometer and processed by a spectrum analyzer to obtain the resonance frequency. Tightness of the clamp was adjusted to vary the resonance frequency. A statistical analysis produced a linear correlation coefficient (R) among the measured ISQ, resonance frequency, and incremental insertion torque. Results: The resonance frequency had high correlation to the incremental insertion torque (R = 0.978), confirming the validity of using RFA for this study. Measured ISQ data were scattered and had low correlation to the resonance frequency (R = 0.214) and the incremental insertion torque (R = 0.386). The spectrum analysis revealed the simultaneous presence of multiple resonance frequencies. Conclusions: For the designed benchtop tests, resonance frequency does indicate implant stability in view of Sawbones density and incremental insertion torque. However, ISQ measurements do not correlate to the resonance frequency and may not reflect the stability when multiple resonance frequencies are present simultaneously. [ABSTRACT FROM AUTHOR]

In this study, the influence of ceramic shield characteristics, including thickness and geometry, on the transmission spectrum and electron density measurements of a ceramic shield cutoff probe (CSC) was investigated to measure high-density or process plasma. Through electromagnetic simulations and circuit modeling, we examined the measurement characteristics of the CSC based on different ceramic shield geometries. When the ceramic shield is sufficiently thin, it does not affect the CSC wave transmission characteristics. However, for a thick ceramic shield, a cutoff frequency shift of up to 3% toward the lower side can occur. This shift is attributed to the electrical properties of the ceramic material, which can function as a parasitic capacitor. In addition, when fabricating a CSC, depending on the shape of the ceramic shield or the method used to couple it with the CSC body, a cutoff frequency shift can occur toward the lower side. The simulation results were validated through experiments, revealing a cutoff frequency shift toward the lower side of up to 18.0% in the simulations and up to 11.6% in the experiments. The findings of this study could assist in high-density or processing plasma measurements using cutoff probes. [ABSTRACT FROM AUTHOR]

The gas-phase rotational spectrum from 8 to 750 GHz and the high-resolution infrared (IR) spectrum of pyridazine (o-C4H4N2) have been analyzed for the ground and four lowest-energy vibrationally excited states. A combined global fit of the rotational and IR data has been obtained using a sextic, centrifugally distorted-rotor Hamiltonian with Coriolis coupling between appropriate states. Coriolis coupling has been addressed in the two lowest-energy coupled dyads (ν16, ν13 and ν24, ν9). Utilizing the Coriolis coupling between the vibrational states of each dyad and the analysis of the IR spectrum for ν16 and ν9, we have determined precise band origins for each of these fundamental states: ν16 (B1) = 361.213 292 7 (17) cm−1, ν13 (A2) = 361.284 082 4 (17) cm−1, ν24 (B2) = 618.969 096 (26) cm−1, and ν9 (A1) = 664.723 378 4 (27) cm−1. Notably, the energy separation in the ν16-ν13 Coriolis-coupled dyad is one of the smallest spectroscopically measured energy separations between vibrational states: 2122.222 (72) MHz or 0.070 789 7 (24) cm−1. Despite ν13 being IR inactive and ν24 having an impractically low-intensity IR intensity, the band origins of all four vibrational states were measured, showcasing the power of combining the data provided by millimeter-wave and high-resolution IR spectra. Additionally, the spectra of pyridazine-dx isotopologues generated for a previous semi-experimental equilibrium structure (reSE) determination allowed us to analyze the two lowest-energy vibrational states of pyridazine for all nine pyridazine-dx isotopologues. Coriolis-coupling terms have been measured for analogous vibrational states across seven isotopologues, both enabling their comparison and providing a new benchmark for computational chemistry. [ABSTRACT FROM AUTHOR]

A high-resolution absorption spectrum of the S1–S0 transition of free-base phthalocyanine was observed and analyzed with improved reliability. The spectrum, with a partially resolved rotational structure, was obtained by using the buffer-gas cooling technique and a single-mode tunable laser. Our new analysis reveals that the S 1 ← S 0 0 0 0 band belongs to the a-type transition, where the electronic transition moment aligns parallel to the NH–HN direction, allowing the assignment of the S1 state to 1B3u. These results agree with a prior study using supersonic expansion and are well supported by theoretical calculations. Interestingly, the rotational constant B in the S1 state, which is often smaller than that in the ground state for typical molecules, was found to be slightly larger than that in the S01Ag state. This suggests a change in the character of π bonds with the electronic excitation. [ABSTRACT FROM AUTHOR]

Small extracellular vesicles (sEVs) are cell-released vesicles ranging from 30-150nm in size. They have garnered increasing attention because of their potential for both the diagnosis and treatment of disease. The diversity of sEVs derives from their biological composition and cargo content. Currently, the isolation of sEV subpopulations is primarily based on bio-physical and affinity-based approaches. Since a standardized definition for sEV subpopulations is yet to be fully established, it is important to further investigate the correlation between the biomolecular composition of sEVs and their physical properties. In this study, we employed a platform combining single-vesicle surface-enhanced Raman spectroscopy (SERS) and machine learning to examine individual sEVs isolated by size-exclusion chromatography (SEC). The biomolecular composition of each vesicle examined was reflected by its corresponding SERS spectral features (biomolecular "fingerprints"), with their roots in the composition of their collective Raman-active bonds. Origins of the SERS spectral features were validated through a comparative analysis between SERS and mass spectrometry (MS). SERS fingerprinting of individual vesicles was effective in overcoming the challenges posed by EV population averaging, allowing for the possibility of analyzing the variations in biomolecular composition between the vesicles of similar and/or different sizes. Using this approach, we uncovered that each of the size-based fractions of sEVs contained particles with predominantly similar SERS spectral features. Indeed, more than 84% of the vesicles residing within a particular group were clearly distinguishable from that of the other EV sub-populations, despite some spectral variations within each sub-population. Our results suggest the possibility that size-based EV fractionation methods produce samples where similarly eluted sEVs are correlated with their respective biochemical contents, as reflected by their SERS spectra. Our findings therefore highlight the possibility that the biogenesis and respective biological functionalities of the various sEV fractions may be inherently different.

Lipids play crucial roles in many biological processes. Mapping spatial distributions and examining the metabolic dynamics of different lipid subtypes in cells and tissues are critical to better understanding their roles in aging and diseases. Commonly used imaging methods (such as mass spectrometry-based, fluorescence labeling, conventional optical imaging) can disrupt the native environment of cells/tissues, have limited spatial or spectral resolution, or cannot distinguish different lipid subtypes. Here we present a hyperspectral imaging platform that integrates a Penalized Reference Matching algorithm with Stimulated Raman Scattering (PRM-SRS) microscopy. Using this platform, we visualize and identify high density lipoprotein particles in human kidney, a high cholesterol to phosphatidylethanolamine ratio inside granule cells of mouse hippocampus, and subcellular distributions of sphingosine and cardiolipin in human brain. Our PRM-SRS displays unique advantages of enhanced chemical specificity, subcellular resolution, and fast data processing in distinguishing lipid subtypes in different organs and species.

The study aimed to develop a potential biomaterial for neuroregeneration by the electrospinning of the biocompatible polymer polyvinylidene fluoride (PVDF) with innovative functionalized boron nitride quantum dots (F-BNQDs) synthesized via green chemistry using the amino acid taurine as a functionalization. The F-BNQDs were characterized and were found to be 16-21 nm in diameter, showed good photoluminescent characteristics, and their elemental composition was confirmed by x-ray photoelectron spectroscopy, Fourier-transform infrared (FTIR), and ultraviolet spectroscopy. The PVDF with F-BNQDs was prepared at three different concentrations, and the resulting electrospun fibers were characterized by scanning electron microscopy, FTIR, thermogravimetric analysis, contact angle, biodegradation, water uptake, Schwann cell cytotoxicity, and cell behavior studies. The results of the study showed that the addition of F-BNQDs to PVDF resulted in enhanced mechanical properties, decreased contact angle, increased degradability, and water uptake. The lactate dehydrogenase assay revealed that 5% BN-PVDF had the lowest cytotoxicity. Fluroscent 4',6-diamidino-2-phenylindole (DAPI) staining showed that the increase in F-BNQD concentration up to 5% BN-PVDF enhanced cell behavior on the electrospun fibers. Therefore, the study concluded that 5% BN-PVDF would be suitable for further testing as a potential biomaterial for neuroregeneration in vivo. Highlights * Functionalized boron nitride quantum dots (F-BNQDs) were prepared using amino acid taurine. * The F-BNQDs were characterized and electrospun with polyvinylidene fluoride (PVDF). * The incorporation of F-BNQDs to PVDF has enhanced its physicochemical properties. * All samples showed a single [beta]phase PVDF. * Schwann cells showed excellent compatibility and cell adhesion on F-BNQDs/PVDF. KEYWORDS electrospinning, functionalized boron nitride quantum dots, PVDF, Schwann cells, taurine, 1 | INTRODUCTION Peripheral nerve injuries have the potential to cause total transection of the nerve, necessitating surgical intervention to enable the regrowth of axons from the injured site to [...]

The preparation of fused silica glass with microstructural patterns has attracted considerable interest, and the process chain of using nano-silica powders mixed with organic polymers to prepare composites for molding, degreasing, and sintering provides a good solution. However, the potential negative effects of organic residues cannot be avoided. In this study, a pattern stencil replication method with silica gel using high-purity quartz fibers as reinforcement is proposed for preparing micropatterned fused silica glass. The microscopic morphology and mechanical properties before and after silica gel drying and the optical properties of fused silica glass obtained by sintering were evaluated via transmission electron microscopy), three-point bending strength test, scanning electron microscopy, X-ray diffraction spectrum analysis, ultraviolet–visible and infrared measurements. The results showed that quartz fiber as a reinforcer could shorten the drying time of the gel and did not degrade the quality of the fused silica glass obtained by sintering. Laser confocal test results showed that microlens arrays were generated by template replication, demonstrating the feasibility of molding fused silica lens arrays with small feature sizes and providing new ideas for the preparation of bulk fused silica glass or micropatterned glass. [ABSTRACT FROM AUTHOR]

We consider the global well-posedness and decay rates for solutions of 3D incompressible micropolar equation in the critical Besov space. Spectrum analysis allows us to find not only parabolic behaviors of solutions, but also damping effect of angular velocity in the low frequencies. Based on this observation, we establish the global well-posedness with more general regularity on the initial data. The approach concerns large time behaviors is so-called the Gevrey method which bases on the parabolic mechanics of the micropolar system. This method enables us even to derive decay of arbitrary higher order derivatives by transforming it into the control of the radius of analyticity under a particular regularity. To bound the growth of the radius of analyticity in general L p Besov spaces, we shall develop some new techniques concern Gevrey estimates, especially an extended Coifman-Meyer theory, to cover those endpoint Lebesgue framework. [ABSTRACT FROM AUTHOR]

The technology of p-type transparent semiconductors is utilized in various fields, and enhancing their performance holds industrial significance. Thus, improving the versatility and efficiency of the p-type transparent conducting oxides (TCO) has become critical for the semiconductor industries and technologies. To be used as hole carrier layes in optoelectronic devices, this study aimed to modify the physical features of nickel oxide (NiO) through a doping approach which may broaden and strengthen the usage of NiO. A cost-effective ultrasonic pyrolysis spray technique was employed for pure and lead (Pb) doped nickel oxide thin film production. The influence of the lead concentration on optical, structural, and morphological traits of the NiO nanostructures was examined via various analyses, including energy-dispersive X-ray spectroscopy (EDAX), scanning electron microscopy (SEM), Photoluminescence, UV–visible spectroscopy, X-Ray Diffraction, and Raman spectroscopy, were utilized to investigate the optical and structural characteristics of these films. In correlation, the X-Ray Diffraction results indicated that the Pb doping induced strain and altered lattice parameters of the grown nanostructures while the cubic phase of NiO maintained. The crystallite size of NiO samples ranged from 31.49 nm to 18.75 nm based on Pb doping concentration which was notably influenced by species and doping content. The UV–vis measurements demonstrated that optical parameters, such as optical band gap, were sensitive to Pb doping ratios. The Raman spectrum analysis confirmed the successful incorporation of Pb ions into NiO. Additionally, the intensity of the PL spectra decreased with increasing Pb content, offering potential applications as window layers in solar cells, smart windows, and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

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Background: Studying the composition rules and evolution mechanisms of genome sequences are core issues in the post-genomic era, and k-mer spectrum analysis of genome sequences is an effective means to solve this problem. Result: We divided total 8-mers of genome sequences into 16 kinds of XY-type due to XY dinucleotides number in 8-mers. Previous works explored that the independent unimodal distributions observed only in three CG-type 8-mer spectra, while non-CG type 8-mer spectra have not the universal phenomenon from prokaryotes to eukaryotes. On this basis, we analyzed the distribution variation of non-CG type 8-mer spectra across 889 animal genome sequences. Following the evolutionary order of animals from primitive to more complex, we found that the spectrum distributions gradually transition from unimodal to tri-modal. The relative distance from the average frequency of each non-CG type 8-mers to the center frequency is different within a species and among different species. For the 8-mers contain CG dinucleotides, we further divided these into 16 subsets, where each 8-mer contains both CG and XY dinucleotides, called XY1_CG1 subsets. We found that the separability values of XY1_CG1 spectra are closely related to the evolution and specificity of animals. Considering the constraint of Chargaff's second parity rule, we finally obtained 10 separability values as the feature set to characterize the evolution state of genome sequences. In order to verify the rationality of the feature set, we used 14 common classification algorithms to perform binary classification tests. The results showed that the accuracy (Acc) ranged between 98.70% and 83.88% among birds, other vertebrates and mammals. Conclusion: We proposed a credible feature set to characterizes the evolution state of genomes and obtained satisfied results by the feature set on large scale classification of animals. [ABSTRACT FROM AUTHOR]

AbstractPurposeMethodsResultsConclusionsThis comprehensive review is designed to elucidate the transformative role and multifaceted applications of ocular hydrogels in contemporary ophthalmic therapeutic strategies, with a particular emphasis on their capability to revolutionize drug delivery mechanisms and optimize patient outcomes.A systematic and structured methodology is employed, initiating with a succinct exploration of prevalent ocular pathologies and delineating the corresponding therapeutic agents. This serves as a precursor for an extensive examination of the diverse methodologies and fabrication techniques integral to the design, development, and application of hydrogels specifically tailored for ophthalmic pharmaceutical delivery. The review further scrutinizes the pivotal manufacturing processes that significantly influence hydrogel efficacy and delves into an analysis of the current spectrum of hydrogel-centric ocular formulations.The review yields illuminating insights into the escalating prominence of ocular hydrogels within the medical community, substantiated by a plethora of ongoing clinical investigations. It reveals the dynamic and perpetually evolving nature of hydrogel research and underscores the extensive applicability and intricate progression of transposing biologics-loaded hydrogels from theoretical frameworks to practical clinical applications.This review accentuates the immense potential and promising future of ocular hydrogels in the realm of ophthalmic care. It not only serves as a comprehensive guide but also as a catalyst for recognizing the transformative potential of hydrogels in augmenting drug delivery mechanisms and enhancing patient outcomes. Furthermore, it draws attention to the inherent challenges and considerations that necessitate careful navigation by researchers and clinicians in this progressive field. [ABSTRACT FROM AUTHOR]

ABSTRACT Bi‐based organic halides have attracted widespread attention as potential substitutes for lead‐based organic halide perovskites and have been explored and applied in many optoelectronic devices. The rational design of organic Bi‐based halides is a popular research topic. In this work, we used benzylammonium (BA) cations to synthesize BA3Bi2I9 (BBI) perovskite material and FA3Bi2I9 (FBI, FA [formamidinium]) as control. We observe that the benzene rings in BA cations overlap with each other due to the benzene rings Π‐Π conjugation in the crystal structure of BBI, which exhibits large interplanar spacing due to large BA ions. BBI has preferential orientation along the (020) crystal plane. Due to conjugation, scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) mapping images indicate that the surface of the BBI thin film is smoother and more uniform than that of the FBI thin film. We fabricated the device by growing thin films of BBI and FBI on ITO interdigital electrodes. The photodetector based on BBI SC exhibits stability and regularity with turning on/off of the light at different intensities (10, 20, 30, and 40 W m−2) and wavelengths (386, 397, 405, and 433 nm). The ultraviolet–visible (UV–vis) absorption and reflection spectrum analysis shows that BBI has a slightly wider bandgap than FBI. This study can provide some ideas for the design Π‐Π conjugation in organic metal halides. [ABSTRACT FROM AUTHOR]

Bimetallic single‐atom‐dimer (SAD) with unique electronic structures and adsorption properties presents exceptional catalytic performance owing to atomic‐level synergistic effects from direct bonding between different metal atoms. However, inherent characteristics of substrate present great challenges in their synthesis and mechanism investigation. Herein, a unique phosphorus modified atomic layer deposition (P‐ALD) strategy is designed to synthesize P‐anchored Pt–W dimers, overcoming substrate limitation (Pt1W1–P/C). Motivated introduction of atomic P site via ALD can effectively anchor one‐to‐one AB bimetallic dimer structure on various substrates, confirmed by X‐ray absorption spectroscopy (XAS). Density functional theory reveals an interatomic synergistic adsorption mechanism, with W as primary hydrogen adsorption site extending to Pt, optimizing hydrogen coverage, leading to 60‐fold increase in mass activity compared to commercial Pt/C in both acidic and alkaline electrolytes. Anion exchange membrane water electrolyzer with ultra‐low loading Pt1W1–P/C (50 µgPt cm−2) catalyst operates durability at 1000 mA cm−2 for 550 h with ultra‐low degradation of 38 µV h−1. Operando XAS confirms hydrogen adsorption pathway between atoms and remarkable self‐healing ability of P–Pt–W–O sites under all‐pH conditions. These findings extend the application domain of SAD to catalytic manufacturing methods and aid in designing advanced materials with multi‐atomic active sites. [ABSTRACT FROM AUTHOR]

There are great challenges in the field of natural product isolation and purification and in the pharmacological study of oligosaccharide monomers. And these isolation and purification processes are still universal problems in the study of natural products (NPs), traditional Chinese medicine (TCM), omics, etc. The same polymer-modified materials designed for the special separation of oligosaccharides, named Sil-epoxy-PEI and Sil-chloropropyl-PEI, were synthesized via two different methods and characterized by scanning electron microscopy combined with energy spectrum analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential as well as surface area analysis, etc. Several nucleotide/nucleoside molecules with different polarities and selectivities were successfully isolated in our laboratory using stainless-steel columns filled with the synthesized material. In addition, the separation of saccharide probes and oligosaccharides mixtures in water extracts of Morinda officinalis were compared in HILIC mode. The results showed that the resolution of separations for the representative analytes of the Sil-epoxy-PEI column was higher than for the Sil-chloropropyl-PEI column, and the developed stationary phase exhibited improved performance compared to hydrothermal carbon, amide columns and other HILIC materials previously reported. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to investigate the effects of Zinc toxicity when fishes are exposed in a controlled environment using two-dimensional correlation spectral analysis. This analysis is superior as subtle spectral changes induced by an external perturbation are not readily noticeable in conventional one-dimensional spectra. A higher decrease in protein and carbohydrates and a lesser decrease in lipids (20%–28%) against the control sample occurs due to Zn toxicity. The lowest value of the bioconcentration factor for Zn shows carbohydrate utilization, which was resolved well in our two-dimensional spectral analysis. Synchronous maps show the predominant changes in protein (1668 cm−1), phospholipids (1771 cm−1), and fatty acids (1707 cm−1). The asynchronous two-dimensional spectra show alteration in phosphodiester stretching of glycogen followed by Amide I. In addition, we explored the importance of principal component analysis coupled two-dimensional spectra analysis which shows weak amide III protein changes. The hetero asynchronous shows well-resolved cross peaks of +(1047, 1389), resulting in improved resolution. The study helps in understanding biomolecular changes of muscle tissues of G. affinis under Zn toxicity using two-dimensional correlation infrared spectral analysis. [ABSTRACT FROM AUTHOR]

Assembly errors can lead to the eccentricity of rotors, further resulting in angular misalignment of rotors and inducing some secondary misalignments, such as the angular misalignment of gears and tilt misalignment of the inner ring of bearings (TMIRB). Ultimately, these misalignments can lead to rubbing faults. However, these misalignments have not raised significant concern, this article investigates their influence on the vibration responses of a dual-rotor-gear-bearing system with rubbing. First, a finite element model (FEM) of the system is built by using an in-house beam element code, and the nonlinear force model of the bearing is established based on the Hertz contact theory. Then, a new model to simulate angular misalignment of gears is proposed by changing the time-varying meshing stiffness (TVMS). Furthermore, the nonlinear dynamic characteristics of the system are investigated in detail under different misalignment angles and rotating speeds, and some interesting conclusions are summarized as follows. Specifically, analyses of the spectrum cascade of radial and axial responses reveal the presence of rich multi-time frequencies and combined frequencies. Moreover, as the misalignment angle increases, the system experiences partial rubbing, the rotating speed threshold (RST) corresponding to initial rubbing decreases, and the mesh stiffness of gears decreases. In summary, the proposed model and the results of the analysis offer valuable insights into the vibration characteristics of such systems and these findings can be instrumental in optimizing their design and operation. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to compare the aging behavior of water-based coatings and solvent-based coatings in sulfuric acid environments and to discuss the related mechanism. Design/methodology/approach: A sulfuric acid solution with a concentration of 5 Wt.% was selected for immersion test at 23°C. The failure behavior of the coating was studied by combining the transformation rules of the macroscopic morphology and basic properties with the results of electrochemical impedance spectrum analysis. Findings: The results showed that the surface smoothness of the water-based coating was lower than that of the solvent-based coating. The glossiness, thickness and hardness of the water-based coating exhibited more significant changes. The electrochemical test also indicated that the water-based coating was infiltrated by a large number of corrosive media, which may have induced corrosion under the coating. In contrast, the solvent-based coating showed good shielding properties, but the adhesion was seriously affected by the corrosive medium. Originality/value: This work clarified the difference of failure behavior and mechanism between water-based coatings and solvent-based coatings in acidic environment and provided a theoretical basis for the selection and mechanism research of anticorrosive coatings. [ABSTRACT FROM AUTHOR]

Two series of vanillin derivatives containing 1,3,4-oxadiazole and 1,3-thiazolidin-4-one scaffolds were prepared and evaluated for their antifungal activity. The results revealed that compounds 6j (29.73 μg/ml) and 7a (38.15 μg/ml) displayed excellent inhibitory activity against the spore of Fusarium solani. The inhibitory activity of compound 7d (10.53 μg/ml) against the spore of Alternaria solani was more than 42-fold that of vanillin. Compound 7a (37.54 μg/ml) showed better antifungal activity against the spore of B. cinerea than positive controls. The cytotoxicity assay confirmed that compounds 6k, 7a, and 7d showed good selectivity and less toxicity to normal mammalian cells. [ABSTRACT FROM AUTHOR]

Investigation of the fruits of Rhododendron molle G. Don led to the isolation of three new grayanane-type diterpenoids, rhodomolleins LIV-LVI (1-3). The structures and absolute configurations of new compounds were fully elucidated by spectroscopic analysis and single-crystal X-ray diffraction, including HRESIMS, 1 D and 2 D NMR data. Compounds 1-3 were evaluated for analgesic activities utilizing an acetic acid-induced writhing test in mice. Compound 1 showed a significant antinociceptive effect with writhe inhibition rates of 72.9% and 100% at doses of 6 mg/kg and 20 mg/kg in mice, respectively. The binding mode of 1 to N-ethylmaleimide-sensitive factor (NSF, PDB: 6IP2) was explored by molecular docking, indicating the presence of hydrogen bond interactions which account for its analgesic activity. [ABSTRACT FROM AUTHOR]

Based on the major components in the leaves, the ashwagandha has been found to exist in several chemotypic forms in India. From the leaves of various accessions of Withania somnifera, which were maintained in our institute, three new steroids namely, 4-acetoxy-20β-hydroxy-1-oxo-witha-2,5,24-trienolide (7), 24,25-dihydro-14α-hydroxy withanolide D (9), 5α,6β,17α,27-tetrahydroxy-1-oxo-witha-2,24-dienolide (12) together with thirteen known withanolides were identified by spectroscopic methods. From the roots and stem of one accession and leaves of another, a new alkyl ester glucoside (4) has also been isolated. The new withanolides 7, 9 and 12 have been tentatively named as withanolide 135 A, withanolide 135B and withanolide 108, respectively. [ABSTRACT FROM AUTHOR]

Aim: To investigate the effects of high‐intensity interval training (HIIT) on periodontitis (PD) progression and behavioural outcomes. Materials and Methods: Forty‐eight Wistar rats were divided into four groups: non‐trained (NT); non‐trained with PD; HIIT with PD; and HIIT. The HIIT protocol, involving daily treadmill sessions, spanned 8 weeks, with PD induced by ligature after the 6th week. Behavioural tests were conducted to assess anxiety and memory. Post euthanasia, we evaluated the systemic inflammatory profile and oxidative stress markers in the hippocampus and amygdala. A morphological evaluation and elemental composition analysis of the mandibular alveolar bone were performed. Results: PD exacerbated alveolar bone level, bone surface damage and alterations in calcium and phosphorus percentages on the bone surface (p <.05), while HIIT attenuated these changes (p <.05). HIIT improved systemic inflammatory markers altered by PD (tumour necrosis factor [TNF]‐α, interleukin [IL]‐10, TNF‐α/IL‐10 and IL‐1β/IL‐10 ratios, p <.05). PD animals exhibited lower total antioxidant capacity and levels of thiobarbituric acid reactive substances in the amygdala and hippocampus, respectively (p <.05). HIIT maintained these parameters at levels similar to those in NT animals. HIIT improved anxiety and memory outcomes altered by PD (p <.05). Conclusions: HIIT attenuates systemic inflammation, anxiety and memory outcomes promoted by PD. [ABSTRACT FROM AUTHOR]

The composition of gamma-ray burst (GRB) jets remained a mystery until recently. In practice, we usually characterize the magnetization of the GRB jets (σ 0) through the ratio between the Poynting flux and matter (baryonic) flux. With the increasing value of σ 0, magnetic energy gradually takes on a dominant role in the acceleration and energy dissipation of the jet, causing the proportion of thermal component in the prompt-emission spectrum of GRBs to gradually decrease or even be completely suppressed. In this work, we conducted an extensive analysis of the time-resolved spectrum for all Fermi GRBs with known redshift, and we diagnose σ 0 for each time bin by contrasting the thermal and nonthermal radiation components. Our results suggest that most GRB jets should contain a significant magnetic energy component, likely with magnetization factors σ 0 ≥ 10. The value of σ 0 seems to vary significantly within the same GRB. Future studies with more samples, especially those with lower-energy spectral information coverage, will further verify our results. [ABSTRACT FROM AUTHOR]

Based on the major components in the leaves, the ashwagandha has been found to exist in several chemotypic forms in India. From the leaves of various accessions of Withania somnifera, which were maintained in our institute, three new steroids namely, 4-acetoxy-20β-hydroxy-1-oxo-witha-2,5,24-trienolide (7), 24,25-dihydro-14α-hydroxy withanolide D (9), 5α,6β,17α,27-tetrahydroxy-1-oxo-witha-2,24-dienolide (12) together with thirteen known withanolides were identified by spectroscopic methods. From the roots and stem of one accession and leaves of another, a new alkyl ester glucoside (4) has also been isolated. The new withanolides 7, 9 and 12 have been tentatively named as withanolide 135 A, withanolide 135B and withanolide 108, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT Silicon nanopowders with nitrogen heterocyclic carbene (NHC) and butyl as stabilizing ligands were synthesized by bottom‐up chemical methods. Transmission electron microscopy (TEM) was used to obtain nanoparticle size distribution with 1.8–2.5‐nm average diameter. Optical characteristics (photoluminescence [PL] and infrared [IR] absorption spectra) of samples were investigated as fabricated and on different steps of irradiation by high‐energy 22.5‐MeV protons. The PL spectral changes are slightly different for two cases, but in general, we can see a decrease in luminescence amplitude with fluence growth up to 4·1014 cm−2, mainly for NHC‐stabilized nanosilicon. Main mechanisms of radiation‐induced changes in nanosilicon sample optical properties are discussed by the joint use of PL and IR spectra analysis. [ABSTRACT FROM AUTHOR]

A robust method for determining the electron temperature and density of atmospheric-pressure non-equilibrium argon plasmas is reported. The methodology is based on the analysis of the continuum and line spectra of the plasma. Assuming that the electron energy distribution function (EEDF) is expressed as a two-temperature generalized EEDF (GEEDF), the gamma value of the GEEDF is determined through a grid search of the continuum spectrum analysis given by the bremsstrahlung process, which minimizes the mean-squared logarithmic error (MSLE). In addition, the relationship between the gamma value and the electron temperature and density is determined. Utilizing this relationship, the electron temperature and density are determined by minimizing the MSLE between the excited-state densities obtained from the line spectrum analysis and numerically calculated using the collisional-radiative model. This methodology yielded results that satisfied both continuum and line spectrum analyses. In addition, the same analysis was conducted either by continuum spectrum analysis or by line spectrum alone to compare the results. [ABSTRACT FROM AUTHOR]

A multi‐object silicon photonic spectrometer with N input ports is proposed and realized by integrating a multi‐channel passband optical filter (POF), a tunable narrow‐band optical filter as well as a calibration‐free N × 1 Mach–Zehnder switch (MZS) array. Here, the multi‐channel POF consisting of a multimode waveguide grating (MWG) and a mode (de)multiplexer is used to achieve a broadened working window and an enhanced dynamic range for the present spectrometer, while the narrow‐band optical filter is realized with a thermally‐tunable Euler micro‐ring resonator (EMR) for achieving a very high spectral resolution. The introduction of the N × 1 MZS enables the time‐division‐multiplexed (TDM) spectrum analysis for multiple objects. In this paper, a multi‐object silicon photonic spectrometer with 16 input ports is demonstrated with an on‐chip loss of less than 3 dB and inter‐channel crosstalk as low as −25 dB. This multi‐object spectrometer can be used to analyze the spectra of 16 objects one by one by setting the 16 × 1 MZS, the resolution is as high as 50 pm, and the working window is ≈84 nm. [ABSTRACT FROM AUTHOR]

Electrical impedance dermography (EID), based on electrical impedance spectroscopy, is a specific technique for the evaluation of skin disorders that relies upon the application and measurement of painless, alternating electrical current. EID assesses pathological changes to the normal composition and architecture of the skin that influence the flow of electrical current, including changes associated with inflammation, keratinocyte and melanocyte carcinogenesis, and scarring. Assessing the electrical properties of the skin across a range of frequencies and in multiple directions of current flow can provide diagnostic information to aid in the identification of pathologic skin conditions. EID holds the promise of serving as a diagnostic biomarker and potential to be used in skin cancer detection and staging. EID may also be useful as a biomarker in monitoring effectiveness of treatment in individual patients and in therapeutic research. This review highlights ongoing efforts to improve mechanistic understanding of skin electrical changes, study of EID in a variety of clinical contexts, and further refine the technology to find greater clinical use in dermatology and dermatologic research. [ABSTRACT FROM AUTHOR]

Multistimuli‐responsive color‐changing materials have potential applications in areas such as chemical sensing and anti‐counterfeiting. In this work, a fluoro‐phenyl‐acetyl‐substituted viologen derivative (FPAV·Cl2) is synthesized, which can form a supramolecular inclusion complex with cucurbit[7]uril (Q[7]) via self‐assembly. Significantly, the resulting inclusion complex FPAV2+@Q[7] in the solid‐state exhibits visual color changes in response to multiple external stimuli including light, heat, and vapors of ammonia and organic amines. The electron spin resonance (ESR) and ultraviolet–visible (UV–vis) spectra analysis reveals that the photochromic, thermochromic, and vapochromic behavior of FPAV2+@Q[7] is due to the generation of FPAV+• free radicals resulting from electron transfer. Furthermore, in the solid‐state, FPAV2+@Q[7] shows controllable fluorescence regulated by its chromic process. Based on the multi stimuli‐responsive color‐changes and fluorescence properties of FPAV2+@Q[7], its practical applications in erasable inkless printing, multiple anti‐counterfeiting processes, visible ammonia/organic amines detection, and information encryption are demonstrated. The supramolecular strategy of encapsulating viologen derivatives into macrocycles provides a general method for fabricating multi stimuli‐responsive chromic materials with multiple practical applications. [ABSTRACT FROM AUTHOR]

• 27-day variations of GCR flux according to measurements of AMS-02 and others. • Parameterization of the amplitude-energy spectrum of variations. • Consequences of the force-field model for short-term modulation. This work presents the results of the analysis of 27-day variations in the flux of galactic protons registered by STEREO, SOHO, and AMS-02 in 2015–2016. We calculate variations' amplitude using several different approaches and propose a description of its energy dependence in the range of magnetic rigidity from approximately 0.3 to 100 GV. We also analyse variations of the solar modulation potential, which is the only parameter of force-field model, and consider the possibility of describing the 27-day variations of galactic cosmic rays within the framework of this model. It is shown that rigidity dependence of the 27-day variations amplitude cannot be properly described using this simple approximation. [ABSTRACT FROM AUTHOR]

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New strategies for converting signals between optical and microwave domains could play a pivotal role in advancing both classical and quantum technologies. Traditional approaches to optical-to-microwave transduction typically perturb or destroy the information encoded on intensity of the light field, eliminating the possibility for further processing or distribution of these signals. In this paper, we introduce an optical-to-microwave conversion method that allows for both detection and spectral analysis of microwave photonic signals without degradation of their information content. This functionality is demonstrated using an optomechanical waveguide integrated with a piezoelectric transducer. Efficient electromechanical and optomechanical coupling within this system permits bidirectional optical-to-microwave conversion with a quantum efficiency of up to −54.16 dB. Leveraging the preservation of the optical field envelope in intramodal Brillouin scattering, we demonstrate a multi-channel microwave photonic filter by transmitting an optical signal through a series of electro-optomechanical waveguide segments, each with distinct resonance frequencies. Such electro-optomechanical systems could offer flexible strategies for remote sensing, channelization, and spectrum analysis in microwave photonics. The authors showcase an optical-to-microwave conversion method using an optomechanical waveguide integrated with a piezoelectric transducer. The presented system allows bidirectional optical-to-microwave conversion with a quantum efficiency of up to—54.16 dB. [ABSTRACT FROM AUTHOR]

Structure elucidation is a stage of paramount importance in the discovery of novel compounds because molecular structure determines their physical, chemical and biological properties. Computational prediction of spectroscopic data, mainly NMR, has become a widely used tool to help in such tasks due to its increasing easiness and reliability. However, despite the continuous increment in CPU calculation power, classical quantum mechanics simulations still require a lot of effort. Accordingly, simulations of large or conformationally complex molecules are impractical. In this context, a growing number of research groups have explored the capabilities of machine learning (ML) algorithms in computational NMR prediction. In parallel, important advances have been made in the development of machine learninginspired methods to correlate the experimental and calculated NMR data to facilitate the structural elucidation process. Here, we have selected some essential papers to review this research area and propose conclusions and future perspectives for the field. [ABSTRACT FROM AUTHOR]

Wireless medical telemetry systems (WMTSs) are typical radio communication–based medical devices that monitor various biological parameters, such as electrocardiograms and respiration rates. In Japan, the assigned frequency band for WMTSs is 400 MHz. However, the issues accounting for poor reception in WMTS constitute major concerns. In this study, we analyzed the effects of electromagnetic interferences (EMIs) caused by other radio communication systems, the intermodulation (IM) effect, and noises generated from electrical devices on WMTS and discussed their management. The 400-MHz frequency band is also shared by other radio communication systems. We showed the instantaneous and impulsive voltages generated from the location-detection system for wandering patients and their potential to exhibit EMI effects on WMTS. Further, we presented the IM effect significantly reduces reception in WMTS. Additionally, the electromagnetic noises generated from electrical devices, such as light-emitting diode lamps and security cameras, can exceed the 400 MHz frequency band as these devices employ the switched-mode power supply and/or central processing unit and radiate wideband emissions. Moreover, we proposed and evaluated simple and facile methods using a simplified spectrum analysis function installed in the WMTS receiver and software-defined radio for evaluating the electromagnetic environment. [ABSTRACT FROM AUTHOR]

A Fourier-transform recording of protactinium in the infrared range is reanalysed with high precision in order to determine the hyperfine interaction constants A and B. Starting with a selection of best lines and least-squares fits of hyperfine structure intervals, large systems of linear equations compare experimental hyperfine peak wavenumbers with a theoretical representation. The theoretical representation is based on Ritz's combination principle and Casimir's formula according to the existing classification. Weighted least-squares fits allow a discrimination between unperturbed and perturbed data such as blended hyperfine structure components. For the first time, the wavenumbers of the hyperfine components of more than 600 lines are fitted using the characteristics of about 250 levels as parameters. When adding adjustable wavenumber-scale correction parameters, global consistency for the whole IR spectrum is obtained with local limits of about 0.3 × 10 - 3 cm - 1 . This demonstrates the high precision in both recording and analysis. The values of the fine structure energies are revised. Standard errors around 0.1 × 10 - 3 cm - 1 for the A constants and 10 - 3 cm - 1 for the B constants and the fine structure energies are achieved. Representative examples illustrate extensive results obtained for atomic protactinium. This high precision facilitates further search for new energy levels, and 20 new levels were presented. Foreword The data presented here are the results of a study carried out at the Laboratoire Aimé Cotton (LAC) at Paris-Orsay in the years 2003 and 2004, when I was there for a research stay. At this time, I worked together with Jean-François Wyart and Annie Ginibre on the re-examination of protactinium spectra that have been measured about 30 years earlier and that were available in the form of a printed list of peak wavenumbers and a printed paper chart of the intensity profile. The spectra had already been analysed, but there was still a lot of additional information that could be extracted from the spectra with time and effort. The review of the data, the selection of the data and the step-by-step optimization of the data set took a lot of time. When I returned to Berlin in 2004, we had made good progress, but in principle, it is like a bottomless pit. We continued together to optimize the data and tried to the finishing touches to it. At some point, we decided that we had reached a 'level of maturity' where the data could be published. We have discussed a lot about how detailed the text should be. This discussion has dragged on over the years and this project has repeatedly been lost in the stream of other everyday tasks. Every now and then there was a small attempt to return to this topic, but it quickly got lost in the daily hustle and bustle. In 2012, we presented the results at a conference. The death of both of them within two years hit me hard. I very much regret that this work was not published earlier. This special volume was the right motivation for me to finally publish this data. I no longer have access neither to the computer programs used at the time, which ran on large computer systems, nor to the original measurement data. I have not been able to find out what happened to the large quantity of paper (printed list of peak wavenumbers anda printed paper chart of spectra). But I have a bunch of input and output files of the calculations that have become a bit jumbled over the years, which contain a lot of information, as well as our unfinished manuscript. The resulting data contain important information for posterity – particularly since the element is radioactive and the experiments to collect laboratory data are unlikely to be repeated any time soon. I think it is worth publishing these data. High precision FT spectra of Pa: analysis of fine and hyperfine structure [ABSTRACT FROM AUTHOR]

Addressing the complexity of cigarette ingredients and the challenges in brand identification, a cigarette brand identification model based on Projection Pursuit based on Fisher's Criterion (PPF) and hyperspectral technology was proposed. Firstly, the PPF projection algorithm was employed to conduct spectral similarity analysis on the original spectra as well as those processed with Multiplicative Scatter Correction (MSC), first-order derivative (1st D), and second-order derivative (2ndD). Secondly, feature wavelength selection was carried out using Successive Projections Algorithm (SPA) and Genetic Algorithm (GA) to enhance the classification performance in subsequent steps. Finally, cigarette brand identification models were established using Support Vector Machine (SVM) and Extreme Gradient Boosting (XGBoost) algorithms, and the personality of the model was evaluated. The results indicated that, in the combination of hyperspectral technology and the PPF projection algorithm, the second-order derivative (2nd D) served as the optimal band processing method, significantly enhancing the spectral separability. The recognition model established based on 2ndD-SPA-SVM emerged as the best model, achieving an overall classification accuracy of 94. 58% and 92. 50% for the training and test sets respectively. Moreover, a greater difference in the proportion of leaf silk and expanded silk among different brand formulations led to a lower similarity value between categories and a higher recognition accuracy. This model can provide a new efficient, fast, accurate, and non-destructive classification and discrimination method for cigarettes of different grades. It offered theoretical support for the application of hyperspectral technology in cigarette brand maintenance, tobacco blend formulation design, and other scenarios. [ABSTRACT FROM AUTHOR]

Blended acquisition offers significant cost and period reduction in seismic data acquisition. However, fired blended sources are usually deployed at off-the-grid (OffG) samples due to obstacle limitation and economic cost considerations. The irregular distribution of coordinates, along with the blending noise, has a detrimental effect on the performance of subsequent seismic processing and imaging. The interpolated multichannel singular spectrum analysis (I-MSSA) algorithm effectively provides on-the-grid deblended results by employing an interpolator, in conjunction with a projected gradient descent strategy. However, the deblending accuracy and computational efficiency of the I-MSSA are still a concern due to the limitations of the traditional singular value decomposition (SVD). To address these limitations, we propose an interpolated fast damped multichannel singular spectrum analysis (I-FDMSSA) rank-reduction algorithm. The proposed algorithm incorporates the damping operator, the randomized SVD (RSVD) and the fast Fourier transform (FFT) strategy. The damping operator can further attenuate the remaining noise in the estimated signal obtained from the truncated SVD, resulting in an improved deblending performance. The RSVD accelerates the rank-reduction process by shrinking the size of the Hankel matrix. To expedite the rank-reduction and anti-diagonal averaging stages without explicitly constructing large-scale block Hankel matrices, the FFT strategy is employed. By incorporating a 2D separable sinc interpolator, the I-FDMSSA enables an efficient and accurate deblending of 3D OffG blended data. The deblending performance and operational efficiency improvements of the proposed I-FDMSSA algorithm over the traditional I-MSSA algorithm are demonstrated through OffG synthetic and field blended data examples. [ABSTRACT FROM AUTHOR]

The massive binary HDE 228766 is composed of an O type primary and an evolved secondary. However, previous qualitative analyses of the composite spectrum have led to a wide discussion about whether the secondary is an Of or a Wolf–Rayet star. We use new observations and our novel QER20 package to disentangle for the first time the spectra of the two stellar components and obtain artefact |$-$| free reconstructed spectra, yielding the more accurate and reliable spectral classifications of O7.5 V((f))z for the primary and O6 Iaf for the secondary. The emission features of the P |$-$| Cygni profiles of the H  |$\beta$| and He i 5876 Å lines, present in the reconstructed spectrum of the secondary, show that this star is at an initial phase of its transition to the WN evolutionary stage. A previously unobserved variable emission, composed of at least four independent features, is seen since 2014 superposed to the H  |$\gamma$| absorption line. Our analysis reveals that these emission features originate from a physically extended region. This could be explained by an episode of enhanced mass-loss in the scenario of a non |$-$| conservative evolution of the binary. [ABSTRACT FROM AUTHOR]

Mn2(C2H6N6)4(NO3)4·2H2O (Mn) as one of the energetic coordination complexes was chosen for high‐pressure research. In this work, Mn was analyzed by in situ Raman scattering, infrared absorption, and synchrotron angle‐dispersive X‐ray diffraction (ADXRD) technologies up to ~20 GPa at room temperature. The vibrational modes of Mn at ambient pressure were comprehensively resolved based on the experimental results. Detailed spectral analyses revealed that Mn underwent three pressure‐induced phase transitions at 0.5, 2.5, and 5.7 GPa, respectively. ADXRD experiments confirmed the existence of these three phase transitions in Raman and infrared spectra analyses. Based on the analysis of the vibrational spectra and the changes of lattice parameters under pressure, it can be considered that the deformation of the 3‐hydrazino‐4‐amino‐1, 2, 4‐triazole (HATr) ligand led to the first phase transition, and the distortion of the triazole ring induced the second phase transition, and the rearrangement of the hydrogen bonds resulted in the third phase transition. In addition, it can be inferred from Raman spectra and ADXRD data that Mn may have experienced the abnormal expansion during the first phase transition. This work may lay the foundation for further investigating the structure and properties of energetic coordination complexes under pressure. [ABSTRACT FROM AUTHOR]

The method of the two neutron monitors was used to analyze the parameters of the rigidity spectrum variations (RSV) of galactic cosmic ray intensity (GCR) flux in solar cycle 24 based on the data from the global network of neutron monitors. This method is an alternative to the least squares method when there are few monitors working stably in a given period, and their use in the least squares method is impossible. Analyses of the changes in exponent γ in the RSV of GCR flux from 2009 to 2019 were studied. The soft RSV (γ = 1.2–1.3) of the GCR flux around the maximum epoch and the hard RSV (γ = 0.6–0.9) around the minimum epoch of solar activity (SA) is the general feature of GCR modulation in the GeV energy scale (5, 50), to which neutron monitors were found to correspond. Therefore, various values of the RSV γ in the considered period show that during the decrease and increase period of SA, the essential changes in the large-scale structure of the heliospheric magnetic field (HMF) fluctuations/turbulence take place. The exponent γ of the RSV of the GCR flux can be considered a significant parameter to investigate the long-period changes in the GCR flux. [ABSTRACT FROM AUTHOR]

As the driving source, highly efficient silicon-based light emission is urgently needed for the realization of optoelectronic integrated chips. Here, we report that enhanced green electroluminescence (EL) can be obtained from oxygen-doped silicon nitride (SiNx:O) films based on an ordered and tunable Ag nanocavity array with a high density by nanosphere lithography and laser irradiation. Compared with that of a pure SiNxO device, the green electroluminescence (EL) from the SiNx:O/Ag nanocavity array device can be increased by 7.1-fold. Moreover, the external quantum efficiency of the green electroluminescence (EL) is enhanced 3-fold for SiNx:O/Ag nanocavity arrays with diameters of 300 nm. The analysis of absorption spectra and the FDTD calculation reveal that the localized surface plasmon (LSP) resonance of size-controllable Ag nanocavity arrays and SiNx:O films play a key role in the strong green EL. Our discovery demonstrates that SiNx:O films coupled with tunable Ag nanocavity arrays are promising for silicon-based light-emitting diode devices of the AI period in the future. [ABSTRACT FROM AUTHOR]

Filter elements based on metamaterial structure are one of the essential schemes for researching the miniaturization of spectral detection systems. The aim of this study is to meet the application requirements of different long-wave infrared signal frequency filtering and improve the detection efficiency of micro-filters. In this paper, a periodic micro-nano-cross-linked hole structure is designed, based on the surface plasmonic polariton resonance effect to realize the extraordinary optical transmission performance of 8 ~ 12 μm long-wave infrared. Based on the surface plasmonic polariton excitation mechanism of periodic micro-nano-structures, the tunable performance of the transmission spectra at five central wavelengths of 8, 9, 10, 11, and 12 μm was achieved by changing the simulation period and the overall period of the model, and the optimal peak transmittance was 88.31% with a half-wave width of 1.31 ± 0.01 μm. The present study summarizes the tuning mode and rule of the micro-nano-cross-linked structure to realize the blue/redshift under the performance of the extraordinary optical transmission, which provides an important reference for the miniaturized structure design of infrared spectral detectors and tunable filtering research and is conducive to the application of broadband filtering spectral chips. [ABSTRACT FROM AUTHOR]

The canonical scenario of cross-flow vortex-induced vibration (VIV) of a circular cylinder in the turbulent regime, which has been studied by several physical experiments in the literature, is reexamined in this study through high-fidelity large-eddy simulations (LES) at a Reynolds number 104. The VIV response (including vibration amplitude and frequency) and hydrodynamic coefficients predicted by the present LES agree with the experimental results better than previous numerical attempts. In addition, several phenomena reported by previous experimental studies are confirmed numerically for the first time. After validating against the experiments, new VIV characteristics and physical mechanisms are explored with confidence. First, a collective analysis on the frequency spectra of the displacement, lift, and velocity signals provides a complete picture of the frequency response of the system. In contrast, the use of a single signal may miss certain aspects of the frequency response, so that caution should be exercised. Second, spanwise correlation of primary vortex shedding is examined, where relatively low correlations in the upper and lower branches are likely because the vortex shedding patterns involve complex vortex generation and interaction. Third, the effect of mass ratio (m*) of the cylinder on the VIV response is analyzed with a range of m* (=1.4–3.4) relevant to cylindrical structures used in offshore engineering (such as subsea pipelines). The variations in the amplitude response, frequency response, and hydrodynamic coefficients with m* and reduced velocity are examined in detail. The present results suggest that a lighter pipeline is more susceptible to the onset of VIV. [ABSTRACT FROM AUTHOR]

In this study, we consider the connection of the hydrodynamic force with vortex shedding behind a stationary sphere in an unbounded fluid at several Reynolds numbers, covering the range of critical transition from plane-symmetric to non-symmetric flow. A principal spectrum analysis (PSA) is employed/proposed to obtain the spectral representation (SR) modes for each time-varying force coefficient; this enables us to identify (i) one single characteristic frequency at R e = 300 , 350, and 380, i.e., the fast frequency f V S which represents the frequency of vortex shedding and (ii) two characteristic frequencies at R e = 390 , 400, and 420: one is the first fast frequency f 1 = f V S , representing the frequency of vortex shedding, and the other is the second fast frequency f 2 , representing the frequency of side oscillations of the vortex flow in the transverse flow direction. In the situations of the latter set of Reynolds numbers, the SR modes indicate that not only the strength but also the phase of shed vortex varies slightly at each successive vortex shedding, and most notably, we have identified rotation of the vorticity pattern in the near wake about the central axis. The PSA-SR mode analysis reveals that these three vortex activities all co-operate at the integer multiples of the greatest common-divisor of the two characteristic frequencies ( f 1 , f 2 ). In other words, the intricate subtlety of vortex shedding behind a stationary sphere can well be uncovered through the PSA-SR mode analysis for establishing the close connections between the force coefficients and the vorticity activities behind the sphere. The present work represents a sequel to our previous study: A spectral force representation and its physical implication for vortex shedding past a stationary or an oscillating circular cylinder at low Reynolds numbers [Lu et al., "A spectral force representation and its physical implication for vortex shedding past a stationary or an oscillating circular cylinder at low Reynolds number," Phys. Fluids 35(5), 053606 (2023)], where we initially proposed the PSA-SR analysis to establish the connections between the force coefficients and the vortex shedding of the circular cylinder under pre-, sub-, and normal synchronization. [ABSTRACT FROM AUTHOR]