Resonance Capture Research Articles

Investigation of 14C(p, γ)15N at low energies

The radiative capture [Formula: see text]C(p, [Formula: see text])[Formula: see text]N is analyzed within the framework of potential model (PM) and R-matrix framework. The capture cross-section was analyzed for non-resonant and resonant transitions within the pathways that involve radiative capture via electric dipole ([Formula: see text]), and magnetic dipole ([Formula: see text]) transitions. The non-resonant transitions include [Formula: see text] via s- and d-wave capture. The resonant transitions include electric dipole ([Formula: see text]), and magnetic dipole ([Formula: see text]) from the three dominant resonant states above the threshold of p[Formula: see text]+[Formula: see text][Formula: see text]C to the ground state of [Formula: see text]N. Based on the total cross-section, the rates associated with p[Formula: see text][Formula: see text]+[Formula: see text][Formula: see text]C[Formula: see text] [Formula: see text][Formula: see text][Formula: see text]N[Formula: see text]+[Formula: see text][Formula: see text] have been analyzed. In this paper, the resonant capture rates dominate compared to the existing data because, at resonant energies the amplitude of the cross-sections have a dominant effect on the radiative capture rates within the T9 = 1.

On estimations of Dawn spacecraft’s capture probability into 1:1 ground-track resonance around Vesta

Abstract This paper develops semi-analytical and analytical methodologies to estimate the probability of the Dawn spacecraft being captured into a 1:1 ground-track resonance around Vesta. The spacecraft, using low-thrust propulsion, approached the asteroid Vesta, and one significant challenge during this phase is crossing ground-track resonances with the asteroid. As the capture phenomenon is dependent on the initial condition of the trajectory, it is necessary to accurately estimate the probability of such a capture. Firstly, the system dynamics are described by a model incorporating Hamiltonian perturbations from the irregular gravitational field up to the second degree and order, and continuous low-thrust that is constant in magnitude and directed in the opposite direction of the spacecraft’s velocity. The resonance region is enclosed by separatrices which are approximated with a fourth-order polynomial for quantitative analysis. The Hamiltonian, serving as a proxy for the system’s energy, changes when the spacecraft crosses the separatrices, and these changes are quantified using a global adaptive quadrature method. Finally, the probability of capture into ground-track resonance is estimated based on the energy change across the separatrices, and the accuracy and efficiency of the developed semi-analytical and analytical methodologies are investigated by comparing them to numerical simulations based on the perturbed Hamilton’s equations of motion. This research makes a significant contribution to the field of astrodynamics by providing a systematic and efficient approach to estimating the probability of resonance capture.

Electron Push-Pull Effect of Benzotrithiophene-Based Covalent Organic Frameworks on the Photocatalytic Degradation of Pharmaceuticals and Personal Care Products.

A covalent organic framework (COF) has emerged as a promising photocatalyst for the removal of pharmaceutical and personal care product (PPCP) contaminants; however, high-performance COF photocatalysts are still scarce. In this study, three COF photocatalysts were successfully synthesized by the condensation of benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarbaldehyde (BTT) with 4,4',4''-(1,3,5-triazine-2,4,6-triyl)trianiline (TAPT), 1,3,5-Tris(4-aminophenyl)benzene (TAPB), and 4,4',4''-nitrilotris(benzenamine) (TAPA), namely, BTT-TAPA, BTT-TAPB, and BTT-TAPT, respectively. The surface areas of BTT-TAPA, BTT-TAPB, and BTT-TAPT were found to be 800.46, 1203.60, and 1413.58 cm2∙g-1, respectively, providing abundant active sites for photocatalytic reactions. Under visible-light irradiation, BTT-TAPT exhibited the highest removal rate of tetracycline (TC), reaching 82.7% after 240 min. The superior photocatalytic performance of BTT-TAPT was attributed to its large specific surface area and the strong electron-acceptor properties of the triazine group. Electron paramagnetic resonance capture experiments and liquid chromatograph mass spectrometer analysis confirmed that superoxide radicals played a pivotal role in the degradation of TC and ciprofloxacin. Moreover, BTT-TAPT exhibited high stability and reproducibility during the photocatalytic degradation process. This study confirms that BTT-based COFs are a class of promising photocatalysts for the degradation of PPCPs in water, and their performance can be further optimized by tuning the structure and composition of the frameworks.

Resonant capture of stars by black hole binaries: extreme eccentricity excitation

ABSTRACT Massive black hole (MBH) binaries in galactic nuclei are one of the leading sources of ${\sim}$mHz gravitational waves (GWs) for future missions such as Laser Interferometer Space Antenna (LISA). However, the poor sky localization of GW interferometers will make it challenging to identify the host galaxy of MBH mergers absent an electromagnetic counterpart. One such counterpart is the tidal disruption of a star that has been captured into mean motion resonance with the inspiralling binary. Here we investigate the production of tidal disruption events (TDEs) through capture into, and subsequent evolution in, orbital resonance. We examine the full non-linear evolution of planar autoresonance for stars that lock into autoresonance with a shrinking MBH binary. Capture into the 2:1 resonance is guaranteed for any realistic astrophysical parameters (given a relatively small MBH binary mass ratio), and the captured star eventually attains an eccentricity $e\approx 1$, leading to a TDE. Stellar discs can be produced around MBHs following an active galactic nucleus episode, and we estimate the TDE rates from resonant capture produced when a secondary MBH begins inspiralling through such a disc. In some cases, the last resonant TDE can occur within a decade of the eventual LISA signal, helping to localize the GW event.

Measurement of the Se78(n,γ)Se79 cross section up to 600 keV at the n_TOF facility at CERN

The Se78(n,γ)Se79 cross section has a high impact on the abundances of Se78 produced during the slow neutron capture process (s process) in massive stars. A measurement of the Se78 radiative neutron capture cross section has been performed at the Neutron Time-of-Flight facility at CERN using a set of liquid scintillation detectors that have been optimized for a low sensitivity to neutrons. We present resonance capture kernels up to 70 keV and cross section from 70 to 600 keV. Maxwellian-averaged cross section (MACS) values were calculated for stellar temperatures between kT=5 and 100 keV, with uncertainties between 4.6% and 5.8%. The new MACS values result in substantial decreases of 20–30% of Se78 abundances produced in the s process in massive stars and AGB stars. Massive stars are now predicted to produce subsolar Se78/Se76 ratios, which is expected since Se76 is an s-only isotope, while solar Se78 abundances have also contributions from other nucleosynthesis processes. Published by the American Physical Society 2024

The Intelligent Diagnosis of a Hydraulic Plunger Pump Based on the MIGLCC-DLSTM Method Using Sound Signals

To fully exploit the rich state and fault information embedded in the acoustic signals of a hydraulic plunger pump, this paper proposes an intelligent diagnostic method based on sound signal analysis. First, acoustic signals were collected under normal and various fault conditions. Then, four distinct acoustic features—Mel Frequency Cepstral Coefficients (MFCCs), Inverse Mel Frequency Cepstral Coefficients (IMFCCs), Gammatone Frequency Cepstral Coefficients (GFCCs), and Linear Prediction Cepstral Coefficients (LPCCs)—were extracted and integrated into a novel hybrid cepstral feature called MIGLCCs. This fusion enhances the model’s ability to distinguish both high- and low-frequency characteristics, resist noise interference, and capture resonance peaks, achieving a complementary advantage. Finally, the MIGLCC feature set was input into a double layer long short-term memory (DLSTM) network to enable intelligent recognition of the hydraulic plunger pump’s operational states. The results indicate that the MIGLCC-DLSTM method achieved a diagnostic accuracy of 99.41% under test conditions. Validation on the CWRU bearing dataset and operational data from a high-pressure servo motor in a turbine system yielded overall recognition accuracies of 99.64% and 98.07%, respectively, demonstrating the robustness and broad application potential of the MIGLCC-DLSTM method.

Resonance capture cascading of non-smooth NES to mitigate multi-modal torsional vibration of MDOF rotor system

Resonance capture cascading of non-smooth NES to mitigate multi-modal torsional vibration of MDOF rotor system

Spin polarization effect on linear polarization of photon emission following resonant electron capture of lithiumlike ions

Spin polarization effect on linear polarization of photon emission following resonant electron capture of lithiumlike ions

Graphene quantum dot modified Bi2MoO6 nanoflower for efficient degradation of BPA under visible light

Graphene quantum dots (GQDs) are a novel type of carbon dot material that has significant application value in the field of catalysis due to their non-toxic, stable, abundant surface functional groups, and quantum confinement effects. A unique composite photocatalyst was constructed by modifying GQDs onto Bi2MoO6 (BMO) microsphere-shaped nano petals using simple hydrothermal and sintering techniques. The structural and morphological characterization results indicate that GQDs with size of 10 ​nm are well dispersed on BMO nanosheets, forming close contacts, which can greatly improve the separation efficiency of photo-generated electron-hole pairs under visible light irradiation. In the evaluation of the catalytic performance of BPA solution (20 ​mg/L) with a catalyst content of 20 ​mg under a simulated light source with a power of 300 ​W, the best degradation performance was achieved by a photocatalyst (G6/BMO) with the GQDs mass ratio of 6 ​%, which degraded over 95 ​% of BPA under visible light within 120 ​min, while pure BMO only degraded about 45 ​% of BPA during the same time period. Even if the 400 ​nm filter is removed and directly exposed to Xe lamp radiation, the degradation performance of the optimal composite catalyst is only slightly improved, indicating that the current GQDs/BMO composite catalyst has extremely strong visible light catalytic activity. The improvement of catalytic performance comes from the effective separation of electron-hole pairs caused by the absorption of electrons by GQDs, and the introduction of GQDs to reduce the band gap and enhance visible light absorption, both of which are beneficial for catalytic reactions. Free radical capture and electron spin resonance (ESR) tests indicate that ·OH and ·O2− are the main active species for BPA degradation. Although the current GQDs/BMO catalysts have a simple structure, their catalytic performance has significantly improved, which will guide the design of other semiconductor based photocatalysts.

Resonant amplitude distribution of the Hilda asteroids and the free-floating planet flyby scenario

In some recent work, we provided a quantitative explanation for the number asymmetry of Jupiter Trojans by hypothesizing a free-floating planet (FFP) flyby into the Solar System. In support of that explanation, this paper examines the influence of the same FFP flyby on the Hilda asteroids, which orbit stably in the 3:2 mean motion resonance with Jupiter. The observed Hilda population exhibits two distinct resonant patterns: (1) a lack of Hildas with resonant amplitudes <40° at eccentricities <0.1; (2) a nearly complete absence of Hildas with amplitudes <20°, regardless of eccentricity. Previous models of Jupiter migration and resonance capture could account for the eccentricity distribution of Hildas but have failed to replicate the unusual absence of those with the smallest resonant amplitudes, which theoretically should be the most stable. Here we report that the FFP flyby can trigger an extremely rapid outward migration of Jupiter, causing a sudden shift in the 3:2 Jovian resonance. Consequently, Hildas with varying eccentricities would have their resonant amplitudes changed by different degrees, leading to the observed resonant patterns. We additionally show that, in our FFP flyby scenario, these patterns are consistently present across different resonant amplitude distributions of primordial Hildas arising from various formation models. We also place constraints on the potential parameters of the FFP, suggesting it should have an eccentricity of 1–1.3 or larger, an inclination up to 30° or higher, and a minimum mass of about 50 Earth masses.

N-coordinated iron sites dispersed in porous carbon frameworks to activate peroxymonosulfate for efficient sulfisoxazole degradation and real hospital wastewater decontamination

Herein, an N-coordinated Fe site dispersed in porous carbon frameworks (Fe-NC) fabricated from zeolitic imidazolate frameworks encapsulated with iron acetylacetonate (Fe(acac)3 @ZIFs) was employed to activate peroxymonosulfate (PMS) for the attenuation of sulfisoxazole (SIZ) and treating real hospital wastewater. The constructed Fe-NC/PMS system exhibited good catalytic stability for SIZ degradation, maintaining excellent degradation performance over multiple cycles with virtually no leaching. The quenching experiments, electron paramagnetic resonance (EPR) capture analyses, and semi-quantitative measurements showed that singlet oxygen (1O2) and high-valent metal-oxo species were mainly responsible for SIZ degradation by Fe-NC/PMS. Significantly, ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) was used to trace 134 pharmaceutical contaminants in real hospital wastewater. Effective degradation was achieved for 87 % of the pharmaceutical contaminants by the Fe-NC/PMS process. Seventy-four pharmaceutical contaminants were eliminated. Taken together, this work successfully established the Fe-NC/PMS technology using the developed iron-based materials and explored its application to real hospital wastewater treatment, providing an eco-friendly and effective strategy for treating wastewater.

Data-Driven Method for Nonlinear Modal Interaction Identification in Fighter Aircraft

The purpose of this paper is to report a new data-driven analysis methodology for identifying nonlinear modal interactions and its application to aeroelastic wind-tunnel data from a generic fighter configuration, which reveals global modal interactions in this system caused by multiple resonance capture events initiated by local nonlinearities. It is shown that during supersonic testing at the Transonic Dynamics Tunnel, vibro-impacts at the embedded external fuel tank shakers on the inboard underwing stations of the generic fighter introduce strong nonlinearity that gives rise to nonlinear modal interactions. Specifically, time–frequency analysis of the acceleration data demonstrates that 6∶5 and 7∶6 transient resonance captures occur across the aircraft exclusively during this vibro-impact forcing window. Further analysis suggests that these resonance captures are dependent on Mach number. These results show experimentally that local vibro-impacts can cause global nonlinear effects in an aeroelastic system and that these effects can be identified using the new methodology herein. The data-driven analysis scheme employed shows applicability to full-aircraft flight test data for identifying nonlinear modal interactions without knowledge of the precise nonlinear contributors.

The K2-24 planetary system revisited by CHEOPS

The planetary system K2-24 is composed of two transiting low-density Neptunians locked in an almost perfect 2:1 resonance and showing large transit time variations (TTVs), and it is an excellent laboratory to search for signatures of planetary migration. Previous studies performed with K2, Spitzer, and RV data tentatively claimed a significant non-zero eccentricity for one or both planets, possibly high enough to challenge the scenario of pure disk migration through resonant capture. With 13 new CHEOPS light curves (seven of planet b, six of planet c), we carried out a global photometric and dynamical re-analysis by including all the available literature data as well. We obtained the most accurate set of planetary parameters to date for the K2-24 system, including radii and masses at 1% and 5% precision (now essentially limited by the uncertainty on stellar parameters) and non-zero eccentricities eb = 0.0498−0.0018+0.0011, ec = 0.0282−0.0007+0.0003 detected at very high significance for both planets. Such relatively large values imply the need for an additional physical mechanism of eccentricity excitation during or after the migration stage. Also, while the accuracy of the previous TTV model had drifted by up to 0.5 days at the current time, we constrained the orbital solution firmly enough to predict the forthcoming transits for the next ~15 years, thus enabling efficient follow-up with top-level facilities such as JWST or ESPRESSO.

Attenuation of Sommerfeld effect in a four DOF vibration system driven by a non-ideal induction motor

The Sommerfeld effect is a phenomenon in which a non-ideal prime mover fails to provide enough energy around the resonance speed in a vibration system, resulting in resonance capture and a nonlinear jump. This study discusses the successful techniques for attenuating the Sommerfeld effect in a vibration system with four degrees of freedom (DOFs) driven by a non-ideal induction motor. The kinetic equations of the system are derived using the Lagrange function. Additionally, the mean rotational speed and stability of a non-ideal motor are studied by energy balance and perturbation analysis method. Then, the relationship between electromagnetic torque and motor speed in the Sommerfeld effect is analyzed. The Sommerfeld effect exists near the natural frequencies (NFs) with electrical frequency increased or decreased. The main reason is that the gradually increasing mechanical load power of the vibrating system near the NFs contradicts the finite electromagnetic output power of the non-ideal induction motor. Moreover, the validity of the proposed methods is demonstrated through numerical analysis and simulation. The Sommerfeld effect can be effectively mitigated by appropriately increasing the damping coefficient, reducing the installation distance, and minimizing both the eccentric mass and eccentricity radius of the rotor.

Temporary Anions of Benzoxazole in Charge-Transfer Cluster Photodetachment.

The photoelectron spectra of cluster anions of superoxide (O2-) solvated by one molecule of benzoxazole (BzOx) reveal two competing photodetachment mechanisms: a direct photoemission from the solvated cluster core and an indirect pathway involving temporary anion states of benzoxazole accessed via the O2-·BzOx → O2·BzOx- charge-transfer transitions. Benzoxazole is a bicyclic unsaturated organic molecule that does not form permanent anions. However, its low-lying vacant π* orbitals permit a resonant capture of the electron emitted from the O2- cluster core. The non-Hermitian theory using a complex absorbing potential predicts the existence of two BzOx- π* resonances within the experimental energy range: resonance A (π1*) at 0.891 eV and resonance B (π2*) at 1.76 eV, relative to the onset of the BzOx + e- continuum at the ground-state geometry of neutral BzOx. Within the clusters, the O2·BzOx- charge-transfer states are partially stabilized relative to the free-electron limit by interactions with the O2 molecule. These interactions depend on the electronic states of both species. The theory predicts that at the O2-·BzOx cluster geometry, the O2(X3Σg-)·BzOx-(A) and O2(a1Δg)·BzOx-(A) states lie at 0.56 and 0.47 eV (vertically) above the respective neutral states. The O2(3Σg-)·BzOx-(B) resonance is found 1.43 eV (vertically) above O2(X3Σg-)·BzOx. Intense signatures of both BzOx- resonances and the three above-mentioned charge-transfer cluster states, O2(X3Σg-)·BzOx-(A), O2(a1Δg)·BzOx-(A), and O2(3Σg-)·BzOx-(B) are observed in the 355 nm (3.495 eV) and 532 nm (2.330 eV) photoelectron spectra of the O2-·BzOx cluster anion.

A flower-like g-C3N4/CDs/Bi2WO6 hierarchical structure for enhanced photocatalytic degradation of tetracycline

Tetracycline (TC), as one of antibiotic emerging pollutants, has posed potential threats to ecological environment and human health because it is hardly biodegradable and prone to be accumulated in water. In this study, g-C3N4/CDs/Bi2WO6 S-scheme heterojunction with flower-like hierarchical structure was synthesized by hydrothermal method. The optimized composite demonstrates significantly enhanced photocatalytic activity with a TC degradation efficiency of 90.1% after 120 min of visible light irradiation and good reusability up to four consecutive cycles. This can be attributed to the improved light capture capability and efficient separation of photo-generated electron-hole pairs in the constructed S-scheme heterojunction. The introduced carbon dots (CDs) can be served as an efficient carrier transport highway, providing a superior photogenerated carrier separation efficiency and an expanded absorption spectrum. As a result, the strongest redox potentials of the CBCN and VBBWO can be retained for participating the photocatalytic reaction. Free radical capture and electron spin resonance experiments indicate that ·O2- and h+ are the principal active species in the g-C3N4/CDs/Bi2WO6 system. This work provides new strategy for the development of advanced materials in the field of photocatalytic treatment of wastewater.

Photocatalytic CO2 reduction and destruction of rhodamine B on Bi0/BiOCl with tunable oxygen vacancies induced by 60 CO γ-rays irradiation

In this work, Bi0/OVs-BiOCl photocatalysts were in-situ constructed by irradiating BiOCl with 60Co γ-rays. The powerful penetrating ability of γ-rays induce the Bi-O bonds in BiOCl to break, thereby leading to the deoxygenation (OVs) and the formation of metal Bi0. The presence of Bi0 and OVs endows the photocatalysts with enhanced separation of photogenerated charges and enriched active sites. Under the excitation of simulated sunlight, the BOC-5 sample with an irradiation dosage of 5 KGy demonstrates the best photocatalytic performance, and the yield of CO on the sample is 2.19 μmol·g−1·h−1, which is 2.27 times higher than that on the reference sample. In-situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) reveals the formation of intermediates during the conversion of CO2 to CO. Under irradiation of a 300 W xenon lamp, the degradation rate of rhodamine B (RhB) on the BOC-5 sample is 0.05843 min−1, which is 3.42 times of that on the reference sample (0.01708 min−1). The main active species in the degradation process were explored using electron paramagnetic resonance (EPR) and free radical capture experiments at room temperature. This study provides a novel strategy for the preparation of BiOCl-based photocatalysts with high photocatalytic activity through 60Co γ-rays irradiation.

Sustainable photocatalytic process using non-silver agent ZnO/P-g-C3N4/Sr2MgSi2O7:Eu2+,Dy3+ for antibacterial activity

Antimicrobials have become a necessity in the post-pandemic era. In contrast to traditional silver-based antimicrobial materials, which are sterilized by silver ions, photocatalytic materials are mainly sterilized by generating reactive oxygen species, but they are limited by light. In this study, the composite coupling of semiconductor photocatalysts with long afterglow materials was designed to form ZnO/P-g-C3N4/Sr2MgSi2O7:Eu2+,Dy3+ (ZPS) for antibacterial ceramics application. The morphological, chemical structure, and optical properties of ZPS were analyzed by scanning electron microscope (SEM), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR), and UV visible diffuse reflectance spectroscopy (UV–vis DRS). The sustainable photocatalytic properties of as-synthesized composites were explored. Furthermore, the antimicrobial ceramics were prepared by incorporating this antibacterial agent into ceramic glazes, which were found to be highly effective against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with a suppression rate of more than 99 %. The results of active species capture and electron spin resonance (ESR) experiments suggested that •O2- was the significant active species of the photocatalytic antimicrobial agent with a contribution of 47.17 % and that ZPS could continuously produce active species in the dark state.

Resonance electron capture by perylene molecules. Relation with negative differential conductance

Five resonant states of long-lived negative molecular ions were defined during the gas-phase resonant electron capture by perylene. Three states are the ground state (0.05 eV) and two shape resonances (0.4 eV and 0.7 eV). Core-excited Feshbach resonance (1.4 eV) transits into a quartet state, which delays the autodetachment of additional electron and causes the negative differential conductance in tunneling transition due to the spin prohibition. Inter-shell resonance (2.5 eV) is mixed with the ground state with the same symmetry and is likely to be stabilized through the light emission with simultaneous transition to a quartet state.

Sol-gel transition effect based on konjac glucomannan thermosensitive hydrogel for photo-assisted uranium extraction

Exploiting the intelligent photocatalysts capable of phase separation provides a promising solution to the removal of uranium, which is expected to solve the difficulty in separation and the poor selectivity of traditional photocatalysts in carbonate-containing uranium wastewater. In this paper, the γ-FeOOH/konjac glucomannan grafted with phenolic hydroxyl groups/poly-N-isopropylacrylamide (γ-FeOOH/KGM(Ga)/PNIPAM) thermosensitive hydrogel is proposed as the photocatalysts for extracting uranium from carbonate-containing uranium wastewater. The dynamic phase transformation is demonstrated to confirm the arbitrary transition of γ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel from a dispersed state with a high specific surface area at low temperatures to a stable aggregated state at high temperatures. Notably, the γ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel achieves a remarkably high rate of 92.3% in the removal of uranium from the wastewater containing carbonates and maintains the efficiency of uranium removal from uranium mine wastewater at over 90%. Relying on electron spin resonance and free radical capture experiment, we reveal the adsorption-reduction-nucleation-crystallization mechanism of uranium on γ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel. Overall, this strategy provides a promising solution to treating uranium-contaminated wastewater, showing a massive potential in water purification.