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A bound state in the continuum (BIC) metasurface (MS) was designed to achieve an ultrahigh quality factor(Q factor) using natural hyperbolic materials, such as hexagonal boron nitride. To investigate the structure's dispersion and Q factor, a unit cell of the MS comprising semicircles and rectangles was designed. This MS structure supports symmetry-protected BICs and exhibits a Q factor of approximately 13 000 at 4.43964 × 1013 Hz. By breaking the MS symmetry, the BICs are converted into quasi-BICs, resulting in quasi-BIC resonance with a high Q factor. Further analysis of the reflection spectra and multipole theory indicates that the toroidal dipole (TD) has the most significant influence on the resonance. Thus, the symmetry-protected BIC can be transformed into the TD resonance with a Q factor by breaking symmetry. [ABSTRACT FROM AUTHOR]

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]

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]

It is important to understand the dynamics of red blood cells (RBCs) in blood flow. This requires the formulation of coarse-grained RBC models that reproduce the hydrodynamic properties of blood accurately. One of the models that successfully reproduces the rheology and morphology of blood has been proposed by Fedosov et al. [Comput. Methods Appl. Mech. Eng. 199, 1937–1948 (2010)]. The proposed RBC model contains several parameters whose values are determined by either various experiments or physical requirements. In this study, we developed a new method of determining parameter values precisely from the fluctuations of the RBC membrane. Specifically, we studied the relationship between the spectra of the fluctuations and model parameters. Characteristic peaks were observed in the spectra, whose peak frequencies were dependent on the parameter values. In addition, we investigated the spectra of the radius of gyration. We identified the peaks originating from the spring potential and the volume-conserving potential appearing in the spectra. These results lead to the precise experimental determination of the parameters used in the RBC model. [ABSTRACT FROM AUTHOR]

Two lanthanide coordination polymers (CP) of Nd(III) and Tb(III) with 2,4,6-pyridinetricarboxylate ligands were synthesized by reacting Nd(III) or Tb(III) chlorides with 2,4,6-pyridinetricarboxylic acid (H3ptc) by hydrothermal method at 180 °C. Their chemical formulas were {[Nd(ptc)(H2O)2]·H2O}n (CP-1) and {[Tb(ptc)(H2O)3]·H2O}n (CP-2). Two compounds were characterized by IR spectra and element analyses. The crystal structures were determined by X-ray single crystal diffraction. CP-1 formed three-dimensional (3D) structure by the connections of coordination bonds between Nd(III) and ptc ligands and CP-2 formed two-dimensional (2D) layered structure. They could produce the characteristic f-f transition luminescence of Nd(III) or Tb(III) ion with the excitations of UV-rays. The lifetime for 5D4 excited state of Tb(III) in CP-2 was 741 μs. And the absolute quantum yield of photoluminescence for CP-2 can reach 60% (λex = 295 nm). [ABSTRACT FROM AUTHOR]

We study the Cauchy problem for the full compressible Navier-Stokes-Maxwell system with a nonconstant background density in R 3. By means of suitable choosing of symmetrizers and weighted energy estimates with some new developments, we establish the global existence and uniqueness of the classical solution provided that the initial data are near this equilibrium. Furthermore, by using the spectrum analysis on the linearized homogeneous system of the full compressible Navier-Stokes-Maxwell equations and refining the convergence property, we obtain the time-algebraic convergence rates of the perturbed solutions. [ABSTRACT FROM AUTHOR]

Here we present the first use of principal component analysis of the full spectrum of a single europium complex to differentiate between structurally-similar analytes. We demonstrate that it can be used to distinguish between the nucleoside phosphate guests AMP, ADP, and ATP. [ABSTRACT FROM AUTHOR]

Hydrogen, a clean energy source, is pivotal in achieving carbon neutrality but presents safety challenges due to its high diffusivity and flammability. This study explores hydrogen leakage acoustics and spatial characteristics under high-pressure, unconfined conditions. Helium, validated as a surrogate gas with a sound pressure difference of <5 dB, was used for safe experimentation. Using Background Oriented Schlieren (BOS) imaging, significant directional and spatial dependencies were identified, with optimal detection at 1.5 m height and highest sound levels between 300° and 360°. The influence of nozzle geometry was also highlighted, with flat nozzles producing progressively higher sound pressure levels compared to circular ones. Threshold flow rates for audible detection were determined, approaching the maximum permissible leakage limit of 118 NL/min in noisy environments. These findings provide a foundation for safer and more effective hydrogen detection systems. [Display omitted] • Helium mimics hydrogen acoustics, <5 dB difference, ensuring safe experiments. • Simulations pinpoint hydrogen's max sound pressure at 300°–360°, 1.5 m height. • Flat nozzles amplify acoustic levels, key to hydrogen safety optimization. • BOS imaging achieves 99% confidence, visualizing hydrogen flow at 0.0025 pixels. [ABSTRACT FROM AUTHOR]

The fundamental investigation on the chemiluminescence characteristics of NH3-based flames is essential for the development of low-cost, real-time optical diagnostic sensor technologies. In this study, we have experimentally examined the chemiluminescence properties of non-premixed ammonia-methane laminar jet flames under various initial NH3 blending ratios (XNH3 from 0.2 to 1.0 in volume) by conducting the emission spectrum analysis within the 200–800 nm band and capturing the distribution images of key excited radicals. The results revealed that the emission spectra of OH*, CH*, CN*, NH*, and NH2* were clearly identifiable. As anticipated, the chemiluminescence characteristics of NH3-CH4 non-premixed flames were significantly influenced by XNH3; i.e., the overall signal intensity decreased monotonically within the 200–400 nm band but increased within the 400–800 nm band as XNH3 increased. The signal intensity characteristics of OH*, CH*, NH*, and NH2*, indicated by radical images, were consistent with the spectrometer measurements. Particularly, it was found that the intensity ratio of CH*/NH2* was an ideal marker of initial XNH3 in present flames, given their sensitivity with XNH3 and relative ease of measurement with the cost-effective sensors designed for invisible wavelengths. Moreover, in the flame front, CH* was located in the oxidant side, while NH2* was in the fuel side with a broader distribution zone. An increase of XNH3 led to greater flame thickness and shifted the peak position of excited radicals far away from the fuel side. [ABSTRACT FROM AUTHOR]

Magneto-optical magnetic field/current sensors are based on the Faraday effect, which involves changing the polarized state of light. Polarimetric methods are therefore used for measuring polarization characteristics. Channeled polarimetry allows polarization information to be obtained from the analysis of the spectral domain. Although this allows the characterization of Faraday materials, the method has not yet been used for detection in magneto-optical sensors. This paper reports experimental results for magnetic field/current detection using the channeled polarimetry method. It is shown that in contrast to other methods, this method allows the detection of the phase shift caused by Faraday rotation alone, making the detection independent of temperature. Although an increase in measurement accuracy is required for practical applications by refining the data processing, the experimental results obtained show that this method offers a new approach to improving the performance of magneto-optical current sensors. [ABSTRACT FROM AUTHOR]

Quantum Random Number Generators (QRNGs) have been theoretically proven to be able to generate completely unpredictable random sequences, and have important applications in many fields. However, the practical implementation of QRNG is always susceptible to the unwanted classical noise or device imperfections, which inevitably diminishes the quality of the generated random bits. It is necessary to perform the post-processing to extract the true quantum randomness contained in raw data generated by the entropy source of QRNG. In this work, a novel post-processing method for QRNG based on Zero-phase Component Analysis (ZCA) whitening is proposed and experimentally verified through both time and spectral domain analysis, which can effectively reduce auto-correlations and flatten the spectrum of the raw data, and enhance the random number generation rate of QRNG. Furthermore, the randomness extraction is performed after ZCA whitening, after which the final random bits can pass the NIST test. [ABSTRACT FROM AUTHOR]

The aim of this study is to verify the possibility of detecting oil in the bottom sediment using a fibre optic system. The presence of oil is assessed on excitation–emission spectra obtained from spectral fluorescence signals of the sediment sample. A factory spectrofluorometer coupled with an experimental fibre optic measurement system was used. During the determination of spectra, the fibre optic system is set at a 45° angle to the sediment surface and placed above its surface. The light exciting the fluorescence and the light emitted by the sediment are transmitted in a combined bundle of fibre optic threads. The analysis of excitation–emission spectra of sediments contaminated with oil shows variability of the shapes of fluorescence spectra depending on the type and degree of oil contamination, which indicates the feasibility of the sensor design for detecting oil in the sediment in situ. [ABSTRACT FROM AUTHOR]

The compound {[Cd (H2IDC) 2 (H2O) 2]·2H2O}n (1) was synthesized via a hydrothermal method, utilizing 4,5-imidazoledicarboxylic acid (H3IDC) and Cd (NO3) 2·4H2O as raw materials. Single crystal X-ray diffraction (SXRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and fluorescence spectroscopy (FL) were employed to ascertain and elucidate the structure of compound 1. SXRD analysis reveals that compound 1 categorized under the P21/n space group of monoclinic crystal system. In compound 1, Cd (Ⅱ) ions coordinate with H2IDC- anions and water molecules to form a six-coordinated octahedral configuration, which is further extended into a three-dimensional structure through hydrogen bonding. Fluorescence spectrum analysis at room temperature indicates that compound 1 exhibits the most intense emission peak at 598 nm when excited at a wavelength of 296 nm.  [ABSTRACT FROM AUTHOR]

A novel approach for the reconstruction of the mode composition of optical radiation in multimode fiber is presented. It is based on the analysis of the reflection spectrum from the multimode fiber Bragg grating. The mode composition of radiation in the multimode fiber with 40 µm core diameter, sustaining 17 transverse LP modes, was experimentally studied. The experimentally obtained spectral reflection peaks from the multimode fiber Bragg grating coincide very well with the theoretically calculated ones. At the same time, additional spectral peaks corresponding to the cross-reflection of some modes into others were discovered. The introduced method also made it possible to determine the parameters of the studied multimode fiber Bragg grating. Furthermore, the presented method allows the determination of the bending losses for different transverse modes of radiation. The obtained results can help to characterize the operation of few-mode or multimode laser systems. [ABSTRACT FROM AUTHOR]

Raman spectroscopy is a rapid, nondestructive analysis technique used in various scientific disciplines, including mineralogy, chemistry, materials science, and biology. The analysis of Raman spectra and the identification of specific substances in unknown samples can be complex and time-consuming due to the large database of Raman spectra. The Raman Match application was developed to simplify and automate the sample identification process through a search and match method. The application integrates the well-established RRUFF Raman database with the Python programming language. It provides a user-friendly graphical interface to load Raman spectra, identify and fit peaks, match peaks to the reference libraries, visualize the results, and generate publication-ready figures. The application offers a swift and automated method for mineral identification using Raman spectroscopy in laboratory and field settings and during planetary exploration missions to extraterrestrial environments with constraints on time and resources. [ABSTRACT FROM AUTHOR]

The endmember extraction is a challenging problem in spectral unmixing (SU) of a mixed pixel in hyperspectral imagery. There are plenty of attempts to solve the endmember extraction problem. Still, the pure pixel assumption-based algorithms have probably been used most in solving the endmember extraction of SU due to the light computational burden. These pure pixel assumption-based algorithms usually follow one of the criteria: (1) Maximum simplex volume or (2) Extreme projection on a subspace. We propose a novel integrated framework that uses both the criteria mentioned above and the proposed one is referred to as the Convexity-based Pure Index (CPI) algorithm. The CPI generates a fixed number of convex sets based on the number of available bands in the hyperspectral image. The algorithm defines the purity score based on the availability of pixels in the convex sets for the two-band data. The CPI has been compared with contemporary algorithms such as Automatic Target Generation Process (ATGP), Vertex Component Analysis (VCA), Pixel Purity Index (PPI), Successive Volume MAXimization (SVMAX), Alternating Volume MAXimization (AVMAX), TRIple-P: P-norm based Pure Pixel identification (TRIP), Successive Decoupled Volume Max–Min (SDVMM), Negative ABundance-Oriented (NABO), and Entropy-based Convex Set Optimization (ECSO). The metrics, Spectral Angle Distance (SAD) and Spectral Information Divergence (SID) used in the comparison were improved up to 5.9 % and 9 % , respectively. The CPI outperforms prevailing algorithms on real benchmark data and new AVIRIS-NG data. The robustness of the CPI is also tested for various noisy synthetic data. The efficacy of the proposed algorithm is also tested by using qualitative analysis by visualizing the spectra comparison, and abundance maps for all real data. [ABSTRACT FROM AUTHOR]

Purpose: This 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. Methods: 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. Results: 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. Conclusions: 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]

Context: In this work, we have studied different properties of a series of fullerenes, from C24 to C50 by confining hydrogen molecule inside their cavity. The compression of the hydrogen molecule upon encapsulation is evidenced by its altered bond length, while a slight expansion of the fullerene cages due to H2 confinement is also noted. The chemical reactivity parameters of both the empty and H2 confined fullerenes are computed, alongside an examination of the energy components through energy decomposition analysis. Analysis of the absorption spectra indicated that both H2 encapsulated and empty fullerenes exhibited absorption in the UV region. Nevertheless, the inclusion of H2 within the fullerene cages appeared to have minimal influence on the reactivity parameters and absorption spectra, as evidenced by the comparison between the sets of empty and H2-confined fullerenes. Methods: The computational work including the geometry optimization, followed by the frequency analysis and other parameters has been achieved using Gaussian09 software. For doing these calculations, B3LYP and CAM-B3LYP functionals along with 6–311 + G(d,p) basis set is used. In addition, MULTIWFN software has been considered for studying bonding analysis and energy decomposition analysis for the systems. [ABSTRACT FROM AUTHOR]

• Skin carotenoid scores correlate with all plasma carotenoids, except lycopene. • There was no confounding of the relationship by race, age, or body mass index. • Lycopene-rich food intake may not be detected as well as other carotenoids. Skin carotenoids can be measured non-invasively using spectroscopy methods to provide a biomarker of total dietary carotenoid and carotenoid-rich fruit and vegetable intake. However, the degree to which skin carotenoid biomarkers reflect intakes of specific carotenoids must be determined for specific devices. Previously, findings were mixed regarding the correlation between reflection spectroscopy (RS)-assessed skin carotenoids and individual plasma carotenoid concentrations. The current study expands on prior analyses to examine the cross-sectional associations between adult RS-assessed skin carotenoids and individual carotenoid species intakes and plasma concentrations, controlling for potential covariates. We hypothesized that RS-assessed skin carotenoid scores would strongly correlate with all major plasma carotenoid species other than lycopene. Cross-sectional data from 2 prior studies (n = 213 and n = 162) examining the validity and sensitivity of RS-assessed skin carotenoids as a biomarker of fruit and vegetable intake were used. Skin carotenoids were assessed using the Veggie Meter, which quantifies combined skin carotenoid concentrations. Plasma concentrations of α-carotene, β-carotene, β-cryptoxanthin, lycopene, and lutein and zeaxanthin were determined using high-performance liquid chromatography. Self-reported carotenoid intake was estimated from validated food frequency questionnaires. Skin carotenoid scores correlated moderately to strongly with individual plasma carotenoid species (Pearson's r = 0.52 to r = 0.78) except for lycopene (r = 0.04 to r = 0.07). Low correlations between skin carotenoid score and lycopene plasma concentrations and intake could be due to differential deposition, preferential oxidation/degradation, and/or device measurement bias. Validating skin carotenoid measurement techniques relative to other concentration biomarkers informs the interpretation of skin carotenoid biomarkers. Using data from 2 prior studies, we examined correlations between reflection spectroscopy-assessed skin carotenoid scores and individual plasma carotenoids. Skin carotenoid scores were strongly correlated with all individual plasma carotenoids (r = 0.52 to r = 0.78) except for lycopene, where the correlations ranged from r = 0.04 to r = 0.07. Lycopene-rich food intake may not be detected well if using the reflection spectroscopy-device to assess dietary interventions. [Display omitted] [ABSTRACT FROM AUTHOR]

Insoluble humic substances-humin (HM) are ubiquitous in the environment and often coexist with iron reducers. Previous research has focused on the electron-donating process from HM to iron reducers; however, the reduction process of HM by iron reducers and its impact on the fate of typical contaminants are still poorly understood. In this study, Shewanella oneidensis MR-1 was selected as a model iron reducer, and its ability to reduce HM and the potential environmental impact of bioreduced HM were investigated. The results showed that S. oneidensis MR-1 reduced HMs extracted from different sources to different extents. This process is highly dependent on lactate concentration, salinity, pH, and dissolved oxygen concentration. Alginate bead experiments indicated that the indirect pathway accounted for 40% of the total electrons transferred from S. oneidensis MR-1 to HM. Electrochemical and spectrochemical analyses further revealed that in addition to flavin, c-type cytochrome may mediate electron transfer. The quinone and iron components may be the main functional groups of HM that accept electrons. Finally, we showed that after being reduced by S. oneidensis MR-1, HM can act as an electron donor for microbial nitrate reduction and the chemical reduction of Cr(VI), with electron-mediation efficiencies of 93% and 56%, respectively. [ABSTRACT FROM AUTHOR]

This study analyzed time series data from six GPS stations within the Tatun Volcano Group (TVG), a long‐dormant volcanic system in northern Taiwan, using multichannel singular spectrum analysis to search for potential spatiotemporally correlated transient deformations. A notable cycle of transient deformation was identified from 2015 to 2020, characterized by ground subsidence and uplift of up to 10 mm, accompanied by asymmetric horizontal motions directed inward and outward toward Dayoukeng, the largest fumarole and hydrothermal area in TVG. Evidence from earthquake focal mechanisms and gas composition, along with preliminary source modeling, suggest that these transient phases were likely caused by the pressure change of shallow hydrothermal systems beneath Dayoukeng. Further analysis of time series data from three long‐operating GPS stations revealed similar patterns of transient motion in the area from 2006 to 2015, indicating that TVG has experienced cyclical deformation, akin to many other volcanic systems worldwide. Plain Language Summary: Monitoring ground deformation in volcanoes is crucial for understanding the underlying processes and providing early warnings of potential hazards. Previous geodetic studies of the long‐dormant Tatun Volcano Group (TVG) in northern Taiwan relied on sporadic data, leading to incomplete insights into its time‐varying deformation behavior. Continuous GPS, however, allows for accurate tracking of surface movements over time, including short‐term changes caused by intermittent volcanic activity. This first GPS study of TVG employed a method called multichannel singular spectrum analysis to identify transient signals in noisy data from six stations. Significant ground deformation was revealed between 2015 and 2020, with the ground sinking and rising by up to 10 mm, along with horizontal movements toward and away from Dayoukeng, a major steam vent area in TVG. This sinking is likely related to changes in the shallow hot water and steam systems beneath Dayoukeng, as suggested by anomalies in earthquake activity and surface gas composition. Additional GPS data from 2006 to 2015 revealed that TVG experienced recurring cycles of ground deformation, closely correlated with local seismic activity. Key Points: Data‐adaptive detection of transient deformation in noisy GPS time seriesCycle of ground deformation first detected in the Tatun Volcano area, where about 7 million people reside nearbyHydrothermal processes may have driven consistent spatiotemporal variations in seismicity and deformation in the Tatun Volcano area [ABSTRACT FROM AUTHOR]

Objective(s): Some forms of breast cancer such as triple-negative phenotype, are serious challenge because of high metastatic cases, high mortality and resistance to conventional therapy motivated the search for alternative treatment approaches. Nanomaterials are promising candidates and suitable alternatives for improving tumor and cancer cell treatments. Materials and methods: Biosynthesis of ZnO NPs by help of Berberis integerrima fruit extract, has been done. Analysis of Zinc Oxide NPs using DLS, FTIR, SEM, and EDS techniques have been performed. Moreover, biological activities of ZnO NPs evaluated through MTT method, Flow cytometry, and real time PCR methods. Biocatalytic and apoptotic activity of ZnO NPs on healthy HFF (human fibroblast cell line), MDA-MB 231, and MDA-MB 468 (triple negative breast cancer cell lines, (TNBC)) evaluated. Furthermore, Bax, Bcl-2 and caspase-3 apoptotic genes expression changes in cancer cells assessed in compare to GAPDH as a house keeping gene. Results: Physico-chemical investigation demonstrated ZnO NPs were confirmed by Berberis integerrima fruit extract for the first time. The MTT assay and Flow cytometry results indicated biocompatibility of the ZnO NPs in normal cell line and high anticancer potential against TNBC MDA-MB-231 and MDA-MB-468 cell lines. The IC50 of ZnO NPs were 104.4 and 44.86, 20.96 after 24 hours for HFF, MDA-MB-231 and MDA-MB-468 cells, respectively. Conclusion: The current research showed a fast, cost effective and ecofriendly method for ZnO NPs nanoparticle synthesis. Furthermore, In vitro data analysis demonstrated biocompatibility and highly anticancer effects of biosynthesized ZnO NPs against TNBC cancerous cells. [ABSTRACT FROM AUTHOR]

In this study, long-term and continuous monitoring of atmospheric radon concentration, temperature, air pressure, and humidity was conducted at China Jinping Underground Laboratory. The impacts of temperature, humidity, and air pressure on radon concentration in the experimental environment were specifically examined, along with the potential interactions among these factors. Moreover, Radon data were denoised using Singular Spectrum Analysis (SSA) to reveal factors that might influence changes in radon concentration. The possible mechanisms by which these environmental factors influence radon migration have also been explored. This research not only provides new insights into the behavior of radon in underground environments but also offers important references for formulating effective radon management and protective actions. [ABSTRACT FROM AUTHOR]

The stability test of multi-station precision machining fixtures can improve the safety of multi-station precision machining fixture. This paper puts forward a stability test method of multi-station precision machining fixtures based on the pressure pulsation amplitude test. The fundamental frequency characteristic detection of airflow pulsation is adopted to collect the stability characteristic parameters of multi-station precision machining machine clamps, and the wave number analysis model of airflow pulsation in the stable state of multi-station precision machining machine clamps is constructed. The time domain characteristic parameter analysis and spectrum gain control are adopted to realize the stability condition parameter analysis and spectrum characteristic decomposition of multi-station precision machining machine clamps. The end-face pulsation attenuation characteristic method of detection is followed to realize noise reduction of the stable air pulsation attenuation signal of multi-station precision machining fixture, and the rotor meshing frequency component of the stable air pulsation attenuation signal of multi-station precision machining fixture is extracted. The multi-scale wavelet air pulsation attenuation signal decomposition is adopted to realize the correlation spectrum characteristic detection of the signal, and the multi-dimensional space fusion is employed to realize signal characteristic clustering, thus realizing the stability detection of multi-station precision machining fixture. The test output shows that the proposed method has better convergence and strong feature clustering in the stability detection of multi-station precision machining machine fixtures, which improves the confidence level of multi-station precision machining machine fixture failure instability detection. [ABSTRACT FROM AUTHOR]

The divalent Eu intermetallic compound EuAl 4 with the BaAl 4 -type structure (space group: I4/mmm) orders antiferromagnetically at 16 K. Al atoms have two crystallographically inequivalent sites, denoted as Al(I) and Al(II). Three 27 Al zero-field NMR spectra in the antiferromagnetic state of EuAl 4 at 4.2 K are detected in the vicinity of 12.8, 19.7 and 41.6 MHz, corresponding to the 27 Al internal magnetic fields of 1.2, 1.8 and 3.7 T, respectively. The 27 Al spectra at 12.8 and 19.7 MHz split into five resonance-lines because of the nuclear quadrupole interaction by I = 5/2. However, the 27 Al spectrum at 41.6 MHz shows a broad line-shape. From analysis of these spectra, the 27 Al spectra at 12.8 and 19.7 MHz correspond to those of the Al(II) site and the spectrum at 41.6 MHz belongs to that of the Al(I) site. [ABSTRACT FROM AUTHOR]

Emulsions in the form of creams, lotions, gels or foams are the most widely used personal care formulations to improve the condition and feel of the skin. Achieving an optimal balance between their performance, effectiveness and sensory profile is essential, with the sensory profile being a key factor in consumer satisfaction and the success of these products in the market. Well‐established methods using highly trained and semi‐trained panels (e.g. Spectrum descriptive analysis, Flash Profile method, Quantitative Descriptive Analysis method and 'Check‐all‐that‐apply') are available and commonly used for the sensory assessment of personal care products. Nevertheless, a common drawback among all these methods is their inherent cost, both in terms of financial resources and time requirements. In recent years, research studies have emerged to address this limitation by investigating potential correlations between tactile sensory attributes and instrumental data associated with the physical characteristics of topical formulations. In other words, significant efforts have been invested in the development of robust instrumental methods specifically designed to accurately predict the sensory description that a panel of assessors could establish. These methods are not only faster, cheaper and more objective compared to traditional sensory testing, but they can also be applied to formulations that have not undergone extensive safety and toxicological testing. This review summarizes the most relevant findings, trends and current challenges in predicting tactile sensory attributes of personal care emulsions based on instrumental parameters. [ABSTRACT FROM AUTHOR]

Water structures take an important role in chemical and biological systems, because the structure and function of a molecule may depend on the structure of water with which the molecule interacts. Near‐infrared (NIR) spectroscopy has been proven to be powerful in analyzing the structure of water due to its sensitive response to OH. However, chemometrics is vitally important in the analysis of NIR spectrum of water due to the low resolution of the spectrum and the complexity of the water structures. In this review, chemometric methods for structural analysis of water in aqueous systems, particularly in chemical and biological processes, by NIR spectroscopy were summarized, from the improvement of spectral resolution to the effective extraction of the spectral information of different water structures. Through the changes of the spectral features of the water structures, the structural transformation of proteins, thermo‐responsive polymers, antifreeze agents, as well as the structural variation of water in the transformation were elucidated. Water was proved to be a good probe for analyzing the structure and interactions in aqueous solutions and chemical/biological processes by NIR spectroscopy. [ABSTRACT FROM AUTHOR]

Singular spectrum analysis is a powerful nonparametric technique used to decompose the original time series into a set of components that can be interpreted as trend, seasonal, and noise. For their part, neural networks are a family of information-processing techniques capable of approximating highly nonlinear functions. This study proposes to improve the precision in the prediction of air quality. For this purpose, a hybrid adaptation is considered. It is based on an integration of the singular spectrum analysis and the recurrent neural network long short-term memory; the SSA is applied to the original time series to split signal and noise, which are then predicted separately and added together to obtain the final forecasts. This hybrid method provided better performance when compared with other methods. [ABSTRACT FROM AUTHOR]

The direction‐of‐arrival (DoA) estimation methods based on coprime array (CA) largely rely on having a sufficient number of snapshots. However, under single‐snapshot conditions typical of vehicle‐mounted imaging radar, CA‐based DoA estimation often suffers from ambiguity leakage, resulting in significant degradation in performance. This paper thoroughly analyses the mechanism of ambiguity leakage in CA by re‐deriving the covariance matrix model under single‐snapshot conditions. To suppress the ambiguity leakage, a triple extended coprime array composed of three pairwise coprime sub‐arrays enhanced coprime constraint is designed. Building on this design, a DoA estimation algorithm based on an iterative adaptive approach is proposed. By leveraging the power spectrum distribution from iterative adaptive approach, a reduced‐noise signal is constructed by retaining only the high‐energy components. Next, the noise subspace using a multi‐stage Wiener filter, and finally, achieve super‐resolution DoA estimation through multiple signal classification spectrum analysis. [ABSTRACT FROM AUTHOR]

Bearings are vital parts of machines that tolerate load and guide rotors to rotate axially the most accurately possible. Bearing assembly is very important for convenient vibration behavior and increasing useful life. In this research, the main probable root cause of mechanical vibration of the electric motor is explained. Three bearings are analyzed. The first bearing has been changed because of bearing failure due to frequency excitation and vibration amplitude. On the first time running the replacement bearing (second analyzed bearing), the vibration, under the unloaded situation, was higher than normal without getting any failure signals excitation. Based on vibration analysis and signal processing, the vibration peak was at 1 x rpm in non-drive end (NDE) of the motor which may let us think about a bad bearing assembly. Inadequate preload conditions, bearing seat, or housing looseness may cause this abnormal vibration amplitude. This paper uses mechanical symptoms and vibration signals to explain the main probable root cause of vibration amplitude. Relative movement based on unadopted fits or axial preload is one of the main causes of the bearing outer ring fretting corrosion. Fretting corrosion and vibration amplitude result from improper fits and bad mounting conditions. This work explains how to interpret vibration signals coming from fretting corrosion. [ABSTRACT FROM AUTHOR]

Dendroochreatene (1), a new phenanthrene derivative with a spirolactone ring, was isolated from the whole Dendrobium ochreatum plant together with 11 known compounds (2–12). The structure of the new compound was elucidated spectroscopically and phenolic compounds were firstly reported from D. ochreatum. Moscatilin (4), major compound isolated from D. ochreatum, was found to be cytotoxic toward H460 lung-cancer cells, with an IC50 value of 147.3 ± 0.9 µM, while loddigesiinol C (7), C-α-methoxy derivative was inactive. [ABSTRACT FROM AUTHOR]

Surface defect detection in mechanical processing mainly adopts manual inspection, which has certain issues including strong dependence on manual experience, low efficiency, and difficulty in online detection. A surface texture elimination method based on improved frequency domain filtering in conjunction with morphological sub-pixel edge detection is put forward in order to address the aforementioned issues with machining surface defects. Firstly, ascertain whether textures exist in the image and determine their feature values using the grayscale co-occurrence matrix. The main energy direction of the textured surface in the frequency domain was then obtained by applying the Fourier transform to the processed surface. An elliptical domain narrow stopband was designed to reduce the energy in the band region corresponding to the processed surface texture and eliminate the processed surface texture. Finally, improve morphology and sub-pixel edge fusion to extract surface defect images. Cracks and scratches have a detectable width of 0.01 mm, a detection accuracy of 97.667%, and a detection time of 0.02 s. Therefore, the combination of machine vision and texture removal technology has achieved the detection of surface scratches and cracks in machining, providing a theoretical basis for defect detection in workpiece processing. [ABSTRACT FROM AUTHOR]

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]

In the present work, it is proposed to use stator current spectrum analysis by Gabor transform (GT) to identify electrical defects in induction motors. Current-based fault detection plays an important role in the proposed work as it overcomes the major pitfalls associated with other conventional sensor-based monitoring. A Poly Phase Induction Motor (IM) of 2 HP, 415 ± 10 % V, 50 Hz is taken for online testing of proposed fault detection at variable speed regime. At varying load situations, the motor's input current is gathered for various fault conditions. After performing frequency spectral subtraction, advanced GT offers signal processing on the collected stator current. The GT coefficients are used for further analysis to estimate and localize the fault. Fault indexing parameter (FIP) is proposed for fault severity estimation. The data acquisition is carried out in LabVIEW environment and processed by MATLAB programming. [ABSTRACT FROM AUTHOR]

Context: Rare earth elements (REE) are indispensable in numerous green technologies owing to their exceptional physical and chemical attributes. Separating REE is a pivotal process to meet the increasing demands of the high-tech industry. Understanding the hydrolysis of REE in aqueous environments marks the initial stride in comprehending their separation mechanisms. Sulfate commonly coexists in high-concentration solutions alongside REE, stemming from mineral processing. We analyzed the hydrolysis of REE and their complexes with sulfate using DFT methods. We present and discuss on the structural characteristics of hydrolysis species and sulfate complexes in alignment with existing experimental data. Estimates of Gibbs free energies for hydrolysis and sulfate complex formation were compared against literature values. REE pose challenges owing to the labile nature of aqua complexes and the pivotal role of system dynamics. We showed that hydrolysis reactions could be suitably modeled, yielding an error margin of approximately 5 kcal mol−1 concerning experimental values, employing the M06 exchange–correlation functional with the SMD implicit solvation model. However, sulfate chemical species proved to be more challenging, exhibiting larger error margins with substantial variations across the REE series. The Raman spectrum analysis of lanthanum sulfate complexes demonstrated excellent agreement with experimental values. Method: We applied the M06, PBE, and PBE0 exchange–correlation functionals combined with def2-TZVP basis sets and SMD to obtain the Gibbs free energies of hydrolysis and sulfate complexation with lanthanides in aqueous solution. The calculations were performed using the ORCA program. [ABSTRACT FROM AUTHOR]

The early fault characteristics of rolling bearings are weak, especially in a strong noise environment, which are more difficult to extract; therefore, a method based on wavelet packet decomposition, multi-verse optimizer, and maximum correlated kurtosis deconvolution for weak fault feature extraction of rolling bearings is proposed. First, the original vibration signal is decomposed using wavelet packet decomposition, followed by proposing a signal reconstruction method combining the Pearson correlation coefficient and energy ratio to effectively remove noise from the original signal. Second, the parameters L and M of Maximum Correlated Kurtosis Deconvolution (MCKD) are optimized using the multi-verse optimizer algorithm to obtain optimal filter settings. Subsequently, the enhanced reconstruction signal fault features are obtained using the optimized MCKD algorithm. Finally, signal fault features are extracted through envelope spectrum analysis, ultimately achieving the extraction of weak fault features in rolling bearings. The simulation and experimental analysis results demonstrate that the wavelet packet decomposition-MMCKD (Multiverse Optimization Algorithm for Maximum Correlated Kurtosis Deconvolution) feature extraction method not only removes noise from the vibration signal of rolling bearings but also enhances weak fault features, enabling the early extraction of subtle fault features in rolling bearings. [ABSTRACT FROM AUTHOR]

The large-span flexible photovoltaic support array is a new wind sensitive structure system, and its vertical and horizontal flow field interference is more significant than that of the single-row photovoltaic. The complexities make it difficult to accurately predict the extreme wind load of photovoltaic array. Taking a typical flexible photovoltaic demonstration project as the object, this paper analyzes the wind pressure characteristics of the single-row flexible photovoltaic surface based on the large eddy simulation method and verities the effectiveness by comparing it with the wind tunnel test. Based on the Davenport method and the Sadek-Simiu algorithm, the peak factor of non-Gaussian wind load is determined and the distribution law of the extreme wind load of photovoltaic array is revealed. Finally, the interrow interference of the array wind load is discussed systematically and the mechanism of the array wind load interference is discussed from the perspectives of spectrum analysis and flow field driving. Results show that the extreme wind load of the largespan flexible photovoltaic bracket array reaches the minimum value at the second windward row, and the interrow interference effect of the array presents a decreasing static wind load and an increasing fluctuating wind load. At 0° and 180° wind direction angles, the wind pressure interference coefficients of the flexible photovoltaic array are 1.09 and 1.14, respectively, and the bending moment interference coefficients are 1.49 and 1.21, respectively. [ABSTRACT FROM AUTHOR]

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]

For long flight duration and low noise emission, efficient and quiet quadcopters have a continuous demand. The toroidal rotor, which is ring-shaped with each blade forming a closed loop, is recognized for its potential to reduce tip vortex intensity, thereby improving aerodynamic efficiency and reducing noise levels. However, existing studies provide limited and sometimes controversial results of toroidal rotor performance relative to conventional rotors. This study aims to conduct a more comprehensive and systematic evaluation by employing a multi-objective optimization framework to design toroidal and conventional rotors for fair comparison. The optimization under the constraint of a required thrust considers objectives of aerodynamic efficiency and noise emission, with the design variable of blade twist angle. The study compares a toroidal 2-blade rotor with conventional 2-blade and 4-blade rotors. The results show that, while the toroidal rotor generates lower noise than conventional 2-blade rotors, it shows lower aerodynamic efficiency. Compared to conventional 4-blade rotors, the toroidal rotor has lower aerodynamic efficiency and larger noise emission. The trend is determined by the effect of rotational speed and blade–vortex interaction, as revealed by flow field analysis. Noise spectrum analysis allows to identify loading and thickness noise contributions and locate the primary noise sources of the toroidal rotor. [ABSTRACT FROM AUTHOR]

Flow-induced vibrations of a two-dimensional circular cylinder in the wake of another stationary equal-sized cylinder under a Reynolds number of 150 are numerically simulated by a well-developed in-house code. The center-to-center distance between two cylinders is 4 diameters, and the downstream cylinder with a mass ratio of 50 is free to oscillate in the transverse direction only. The instantaneous frequencies of lift forces acting on both cylinders are obtained by the combined singular spectrum analysis and Hilbert transform method. The time-varying frequencies are consistent with those obtained by the wavelet transform of the original lift forces and also show very good agreement with the vortex shedding frequencies from both cylinders. The time-varying frequency and envelope of lift forces acting on the downstream cylinder are the result of nonlinear fluid–structure interactions, which is ascribed to the presence of multi-frequency components in the frequency spectrum obtained by harmonic analysis. Vibration of the downstream cylinder is the result of vortex shedding from both cylinders. The vortex shedding frequency from the downstream cylinder is greatly influenced by the wake from the upstream cylinder. On the other hand, the movement of the downstream cylinder slightly affects the vortex shedding frequency from the upstream cylinder. Consequently, the cylinder movement is locked upon the natural frequency when the vortex shedding frequency is close to the value of 0.155 in stationary situation, which results in a small synchronized region of the reduced velocity ranging from 6.2 to 6.4. [ABSTRACT FROM AUTHOR]

The characteristics of the wake generated by an underwater sphere in the presence of regular free surface waves are investigated. Based on the spectral wave explicit Navier–Stokes equations decomposition strategy, the incident waves are prescribed based on spectral wave models, and the wake characteristics generated by the underwater sphere are determined using a computational fluid dynamics solver. The effects of the wavelength of the surface waves and the Froude number on the wake characteristics are investigated. The results show that the existence of free surface waves can distort the wake patterns, causing them to shift from the classical V-shaped Kelvin wake to an Ω -shape. Analysis of the spectrum indicates that the distortion of wake patterns is mainly determined by the wave–wave interactions. [ABSTRACT FROM AUTHOR]

Purpose: This study investigates the effect of voice-focus adjustments on oronasal balance and auditory feedback control of speech via analyzing spectral distribution, perceived loudness, and nasal vibrations during sustained phonation and passage reading. Method: Twenty-five speech-language pathologists sustained /a/ and read passages with forward, backward, and natural voice focuses in quiet and noisy conditions. The low-frequency power (LFP) below 3 Hz of vocal fundamental frequency was analyzed to access audio-vocal feedback control. Long-term average spectra of speech were converted to phon spectra based on equalloudness contours ISO 226:2003 to estimate perceived loudness of self-voice across different conditions. Nasal vibrations were also recorded using a digital accelerometer to measure oronasal coupling. Results: Forward-focused voice enhanced the nasal acceleration and reduced LFP, suggesting that increasing the degree of oronasal coupling can improve audio-vocal feedback control compared to natural and backward-focused voices. Voice-focus adjustments were most related to average power and phon values in the 0.2- to 0.3-kHz band. In noise, perceived loudness in the 0.5- to 2.3-kHz band effectively predicted LFP, outperforming the average spectral power of the same band. Conclusions: Voice-focus adjustments significantly impact both the acoustic transfer function of the vocal tract and the spontaneous fine-tuning of audio-vocal integration. This influence becomes particularly pronounced when sound intensity or perceived loudness is changed within the frequency range of 0.2-2.3 kHz, depending on the voice focus selected by the speakers. Supplemental Material: https://doi.org/10.23641/asha.27183483 [ABSTRACT FROM AUTHOR]

The present study deals with the dynamics of microelectromechanical system (MEMS) resonators, especially the exploration of strange non-chaotic attractor (SNA) in MEMS resonators. SNAs often arise in systems driven by quasiperiodic forces, where the system is subjected to multiple frequencies that are incommensurate. When we apply the quasiperiodic forces, we identify the presence of SNA regions in the MEMS oscillators through bifurcation and Lyapunov analysis. Subsequently, we analyse the route of SNA in the considered system. In our analysis, the first identified route to SNA is the fractilisation route which is validated through various analyses, such as Poincaré map, distribution of finite-time Lyapunov exponents, Lyapunov variance, singular continuous spectrum and recurrence analysis. Moreover, two additional routes to SNA, namely Haegy–Heamel route and intermittency route, are identified and thoroughly investigated, and the presence of SNA is confirmed using singular continuous spectrum analysis. This work helps to understand SNA that can be important in fields like signal processing, where distinguishing between chaotic and non-chaotic signals is crucial. In particular, the emergence and characterisation of SNAs in MEMS resonators open avenues for further research and applications in nonlinear dynamics and chaotic systems. [ABSTRACT FROM AUTHOR]

Antiferroelectric–ferroelectric phase transition in antiferroelectric (AFE) materials usually triggers high-performance electrocaloric effect (ECE), as represented by PbZrO3-based AFE. As an isostructure to PbZrO3, EC research in PbHfO3-based AFE ceramics are significantly left out. In this work, temperature dependent electrocaloric performances in Pb0.97La0.02(Hf0.92Ti0.08)O3 with typical AFE features are explored, and rhombohedral ferroelectric (FER), AFE1 (A1, Pbam), and AFE2 (A2, Imma) triple phases are induced as temperature increases. This leads to dual coexisting regions with FER-to-A1 and A1-to-A2 at a temperature of ∼20 °C and ∼100 °C, respectively, where local EC maxima are produced with an ΔT ∼0.06 K and ΔT ∼0.16 K (E = 70 kV/cm). These are certified by comprehensive characterizations of in situ x-ray diffractometer, AFE electrical properties, and Raman spectra analysis. This strongly indicates that AFE (Pbam)-to-AFE (Imma) phase transition could efficiently optimize ECE in PbHfO3-based AFE, in addition to the conventional understandings of FE–paraelectric and AFE–paraelectric modulation strategy. This work not only presents the potential of PbHfO3-based AFE in solid-state cooling applications but also serves as a catalyst for further seeking for high-EC AFE materials. [ABSTRACT FROM AUTHOR]

In this study, the failure of a certain type of gearbox of a high-speed locomotive group with cracks is examined, and a gearbox failure assessment method that considers the coupled vibration is established and combined with mechanical signal and frequency signal to determine the basis for judging the failure of a faulty gearbox. First, according to the mechanical model of the finite element calculation, we determined the stress weak links and then the layout response stress measurement points and acceleration measurement points. We then calculated the gearbox ratio, meshing frequency, vibration frequency, mechanical response, modal response, and other frequency characteristics using the Hilbert–Huang transform (HHT) method and the fast Fourier transform (FFT) algorithm to analyze the vibration signals generated by different speeds and wheel out-of-roundness conditions. These were used to calculate the frequency of the different vibration sources of the mechanical response on the weak areas. The frequency correlations of the different vibration sources on the mechanical response in the weak areas were then analyzed, and the vibration transmission law of the gearbox case was obtained. The fault determination criterion was then determined, and the final cause of the fault was obtained. [ABSTRACT FROM AUTHOR]

Developing metal‐free carbon catalysts is critical to achieve the electrosynthesis of hydrogen peroxide (H2O2) via two‐electron oxygen reduction reaction (2e− ORR) using seawater as electrolyte. Herein, N‐rich doped carbon (NC) is synthesized by directly pyrolyzing guanine as both N and C sources, which can facilitate the formation of ultrahigh‐N dopant (up to 33.89 at.%), and their ratios. The NC obtained at 700 °C with hydrogenated pyridine‐N and pyrrole‐N (3:2) dopants exhibits a superior selectivity of H2O2 (up to 96%), high mass activity of 545.5 A g−1 at 0.2 V versus RHE and stable production of H2O2 with 16.8 molgcat−1h−1${\rm{mol}}\;{\rm{g}}_{{\rm{cat}}}^{ - 1}{{{\rm{h}}}^{ - 1}}$ in 0.5 M NaCl. In situ Fourier transform infrared spectrum analysis proves that hydrogenated pyridine‐N and pyrrole‐N dopants play a critical role in constructing metal‐free active sites for the synthesis of H2O2. Meanwhile, theoretical calculations further reveal that compared to non‐hydrogenated N dopants, hydrogenated pyridine and pyrrole N can tune the projected density of states of 2pz orbitals of their adjacent carbon atoms approaching Fermi Level, enhancing *OOH to H2O2 through 2e− ORR rather than H2O via 4e− ORR. This work provides new insights for developing metal‐free catalysts for efficient electrosynthesis of H2O2 using seawater resources as promising electrolytes. [ABSTRACT FROM AUTHOR]

Polycrystalline magnesium aluminate spinel (PMAS) ceramics is a kind of transparent oxide ceramic with the advantages of high hardness, high mechanical strength, thermal stability and chemical corrosion resistance. The optical transmittance and infrared absorption edge of PMAS ceramic are better than that of sapphire and ALON in the mid-infrared band with the wavelengths greater than 4.5 μm, which makes it as an ideal material for manufacturing the optics used in the fields of transparent armor protection, infrared optical window and infrared missile dome. However, the hardness of PMAS ceramics is close to that of sapphire, and the brittleness is greater than that of sapphire, which brings great challenges to ultra-precision ductile grinding. In this paper, the surface characteristics and damage mechanisms in ultra-precision grinding of PMAS ceramics were systematically researched based on AE signals monitoring. Firstly, the effects of grinding depth, feed speed and grain size on the surface characteristics were studied in detail. Secondly, the influences of grinding depth and feed speed on the damage characteristics of PMAS ceramics were researched based on energy spectrum analysis of AE signals. Thirdly, the evolution mechanisms of material removal modes and damage characteristics were revealed based on time-frequency analysis of AE signals. Then, the damage types on ductile surfaces and initiation mechanisms of damage crack were investigated. Ultimately, the crack-free ductile surfaces and surface roughness (Sa) of 3 nm were achieved through ultra-precision grinding. [ABSTRACT FROM AUTHOR]