Intrinsic Resonance Research Articles

Metamaterial‐Augmented Head‐Mounted Audio Module

AbstractRecent developments in metamaterial research have shown promising progress in overcoming the fundamental physical limitations of acoustics. While the majority of this research is curiosity‐driven and focused on fundamental physics, there has been a scarcity of acoustic metamaterials research that can have a direct and immediate impact on real‐world applications. In this study, an acoustic metamaterial inside a head‐mounted audio module is incorporate to achieve a 3–7 dB broadband sound pressure level (SPL) improvement in the bass range (50–700 Hz), which is the most challenging frequency range for radiation enhancement. The adoption of the acoustic metamaterial not only enhances voltage sensitivity near the intrinsic metamaterial resonance frequency, but also extends the broadband enhancement to a lower transducer resonance frequency by carefully engineering the metamaterial‐transducer resonant coupling. The improvement of the audio module is demonstrated through fully coupled electrical‐mechanical‐acoustical numerical simulations using finite element analysis, which are validated against comprehensive measurements including electrical impedance analysis, speaker diaphragm displacement analysis, voltage sensitivity and power sensitivity analysis, and spectrogram. This study not only offers a promising path to improve the audio module quality without increasing the size, but also represents an important milestone toward using acoustic metamaterial research to solve audio industry challenges.

Intrinsic spin Hall resonance in Bi-based Janus monolayers

Intrinsic spin Hall resonance in Bi-based Janus monolayers

Ultrahigh Sensitivity Solar‐Blind UV Detection via Multistage‐Concentric‐Annulus Architecture Metasurface

AbstractHigh‐sensitivity photodetection capability has become an indispensable requirement for detecting feeble solar‐blind ultraviolet (UV) light. Micro‐nano metallic metasurface structures are employed to enhance the detector photoelectric performances. However, existing approaches are confronted with bottlenecks of structure simplification and efficacy mediocrity. Here, a distinctive diamond solar‐blind UV photodetector with a synthetic multistage‐concentric‐annulus (MCA) architecture metasurface is reported, which is prepared through a facile and peculiar Fraunhofer diffraction technique. The detector achieves an excellent photo‐to‐dark‐current ratio of 2.4×108 and maintains an extremely low dark current on the order of pA magnitude. The intrinsic response peak and resonance absorption phenomenon in solar‐blind UV are evident from the optical properties. Moreover, the surface potential distribution intuitively reveals that plasmon resonance enhances the UV scattering and absorption cross sections, thus facilitating the photogeneration of carriers. Meanwhile, it expressly demonstrates that multi‐level dipole interaction in the MCA structure accelerates the separation and extraction of electron–hole pairs through enhancing the localized electric field intensity. In addition, a wide range of variable temperature measurements further prove the device possesses capacity for working in extreme environments. This photodetection technology by virtue of a delicate and viable diffraction metasurface is anticipated to provide a leap forward for future applications in wide‐band‐gap semiconductor UV detectors.

Impedance optimization by inserting of flaky Fe3O4/FeS in PANI-derived amorphous carbon for wide band electromagnetic protection

To against the excessive electromagnetic radiation in the current situation, herein the PANI-derived carbon block with flaky Fe3O4/FeS inserted was obtained via a facile route of co-chemical precipitation, low temperature polymerization and vacuum calcination. It discovers that the component of composites and disordered structures in carbon can be regulated by changing the additive amount of iron oxide, and hence the modified electromagnetic parameters to optimize the impedance matching between free air and composites can be achieved as well. On this basis, by optimizing the coupled effect of intrinsic polarizations, conductive dissipation, magnetic resonance and eddy current wastage, the PDC/Fe3O4/FeS composite realizes the efficient microwave absorption within a broad range of 6.55 GHz, covering the entire Ku band for only 2.2 mm thickness of absorber. The work offers a flexible strategy to synthesize desired candidate for broadband electromagnetic protection.

Electromagnetic deactivation spectroscopy of human coronavirus 229E

An investigation of the deactivation of pathogens using electromagnetic waves in the microwave region of the spectrum is achieved using custom-built waveguide structures. The waveguides feature sub-wavelength gratings to allow the integration of an air cooling system without disturbing the internal propagating fields. The waveguides are tapered to accommodate an experimental sample internally with sufficient surrounding airflow. The proposed methodology allows for precise control over power densities due to the well-defined fundamental mode excited in each waveguide, in addition to temperature control of the sample due to microwave exposure over time. Human coronavirus (HCoV-229E) is investigated over the 0–40 GHz range, where a peak 3-log viral reduction is observed in the 15.0–19.5 GHz sub-band. We conclude HCoV-229E has an intrinsic resonance in this range, where nonthermal structure damage is optimal through the structure-resonant energy transfer effect.

Booster free from spin resonance for future 100-km-scale circular e+e− colliders

Acceleration of polarized electron~(positron) beams in a booster synchrotron may suffer from depolarization due to crossings of many spin depolarization resonances, which could limit its applications. We have studied the spin depolarization resonance structure of a 100~km scale booster lattice of the Circular Electron Positron Collider~(CEPC). The lattice has 8 arc regions with hundreds of FODO cells, interleaved with straight sections, which leads to a high periodicity. Our analysis shows the contributions to the strength of intrinsic and imperfection spin resonances add up coherently near the super strong resonances beyond 120 GeV, but mostly cancel out and result in generally weak resonance strengths at lower beam energies. Detailed simulations confirm that beam polarization can be mostly maintained in the fast acceleration to 45.6 GeV and 80 GeV, but severe depolarization may occur at even higher energies. This study suggests the possibility of acceleration of polarized electron~(positron) beams to ultra-high beam energies without the help of Siberian snakes, and supports injecting highly polarized beams into the collider rings as an attractive solution for resonant depolarization measurements and longitudinal polarized colliding beam experiments for future 100~km scale circular e$^{+}$e$^{-}$ colliders.

Nanoparticle-Based MRI-Guided Tumor Microenvironment Heating via the Synergistic Effect of Ferroptosis and Inhibition of TGF-β Signaling.

Although induction of ferroptosis and inhibition of transforming growth factor-β (TGF-β) signaling are both effective ways to reform the tumor microenvironment (TME) and render low-immunogenic tumors responsive to immune checkpoint inhibitor (ICI) therapy, dose-limiting side effects remain major obstacles hindering their clinical application. Herein, a novel sorafenib and anti-TGF-β antibody loaded Fe3 O4 /Gd2 O3 hybrid nanoparticles with conjugation of RGD dimer (FeGd-HN@Sorafenib@TGF-β-antibody@RGD2, FG-STR) is developed. Sorafenib significantly enhances FeGd-HN-triggered ferroptosis and improves maturation and phagocytosis of dendritic cells (DCs) by inducing damage-associated molecular patterns released from ferroptotic cancer cells, while the anti-TGF-β antibody further synergizes with enhanced ferroptosis to promote DC maturation and the recruitment of CD8+ T cells, thus heating the TME. Moreover, incorporation of RGD2 facilitates uptake of the FG-STR in tumor cells which led to a significant dosage reduction of both sorafenib and anti-TGF-β antibody to avoid dose-limiting toxicities. Finally, in vitro and in vivo experiments shows that FG-STR has significantly superior intrinsic magnetic resonance imaging (MRI) capability than that of Gadovist, effectively inhibits tumor growth and lung metastasis, and increased the efficacy of anti-programmed cell death-1 treatment. Taken together, this study provides a promising strategy for new advanced MRI-guided TME heating therapies. This article is protected by copyright. All rights reserved.

Orthogonalization of the measuring basis of triaxial vibration transducers by the method of successive approximations

The transversal sensitivity of tri-axial vibration transducers, which have found vast application in various vibration measuring and material testing systems, decreases the accuracy of measurements. We present a solution to the problem of eliminating the error attributed to the presence of the transverse sensitivity. The measurement error depends on many factors including the ratio of vibration components along the sensitivity axes, the width of the vibration spectrum, and the presence of intrinsic resonances of the vibration transducers in the main and transverse directions. The developed method provides almost complete compensation of the error. Analysis of the components of sensitivity vectors along the measuring directions showed that the transversal sensitivity vectors are in fact the parasitic penetrations from other directions, and can be decomposed along the measuring axes. To orthogonalize the sensitivity vectors during calibration, the sensitivity vectors should be rotated until they coincide with the orthogonal directions. A measuring basis with zero transverse sensitivities is thus obtained, and the sensitivity matrix is reduced to a diagonal form. With this approach the fundamentals and practical algorithm using successive approximations of triaxial transducer calibration with orthogonalization are outlined. Each orthogonalization step is illustrated by the current sensitivity matrix, showing the progress of transversal sensitivity reduction. The results of the developed tri-axial transducer coupled to a special preamplifier-converter with transversal sensitivities reduced to nearly zero values using the developed method are presented. Since calibration is carried out without dismantling of a vibration transducer, it can be carried out not only during its manufacture, but also during verification upon operation, which increases the service life. The use of the described technique not only improves the metrological parameters of vibration transducers, but also provides a significant reduction of the requirements for the accuracy of manufacturing their measuring system, thus reducing the production costs. The presented method is promising for the developing new precise multi-axis vibration transducers and measuring systems on their base.

In situ construction of complex spinel ferrimagnet in multi-elemental alloy for modulating natural resonance and highly efficient electromagnetic absorption

The contradiction between the demand for highly efficient low-frequency electromagnetic wave (EMW) absorption materials and the relatively poor permeability of existing absorbers has become increasingly prominent. However, the intrinsic natural resonance in magnetic material hinders the modulation and enhancement of permeability. Herein, (FeCoNiCu)xCr3−xO4 complex spinel ferrimagnets (CSFMs) are constructed in situ in multi-elemental alloy powders (MEAs) for the first time, via annealing treatment. The microstructure and composition of the CSFMs are regulated by adjusting the annealing temperature, aiming to modulate the natural resonance frequency and achieve highly efficient megahertz (MHz) electromagnetic absorption. Simultaneously, annealing treatment improves the crystal integrity, which is conducive to enhancing intergranular magnetic coupling to elevate permeability temperature stability and the Curie temperature. The minimum reflection loss value of the MEAs/CSFMs composites is less than −7 dB at 3 mm and the effective EMW absorption bandwidth maintains between 425 and 470 MHz at 5 mm from −50 to 150 °C. In addition, the MEAs/CSFMs composites also exhibit excellent oxidation resistance and corrosion resistance due to the oxide layer on the surface. This work offers a new and tunable strategy toward modulating the natural resonance frequency for efficient temperature-stable broadband EMW absorption at specific frequency bands.

Thermoelectricity in bilayer graphene superlattices

Low-dimensional thermoelectricity is based on the redistribution-accumulation of the electron density of states by reducing the dimension of thermoelectric structures. Superlattices are the archetype of these structures due to the formation of energy minibands and minigaps. Here, we study for the first time the thermoelectric response of gated bilayer graphene superlattices (GBGSLs). The study is based on the four-band effective Dirac Hamiltonian, the hybrid matrix method and the Landauer-Büttiker formalism. We analyze the Seebeck coefficient, the power factor, figure of merit, output power and efficiency for different temperatures and different superlattice structural parameters. We pay special attention to the impact of not only minibands and minigaps on the thermoelectric properties, but also to intrinsic resonances in bilayer graphene structures such as Breit-Wigner, Fano and hybrid resonances. In particular, we analyze the interplay between minibands and Fano resonances as a possible mechanism to improve the thermoelectric response of GBGSLs. We also compute the density of states to know if the redistribution-accumulation of electron states is implicated in the thermoelectric response of GBGSLs.

Myeloperoxidase-Sensitive T1 and T2 Switchable MR Imaging for Diagnosis of Nonalcoholic Steatohepatitis.

Nonalcoholic steatohepatitis (NASH) is the critical stage in the development of nonalcoholic fatty liver disease (NAFLD) from simple and reversible steatosis to irreversible cirrhosis and even hepatocellular carcinoma (HCC). Thus, the diagnosis of NASH is important for preventing the progress of NAFLD into a fatal condition. The oxidative enzyme myeloperoxidase (MPO), which is mostly produced by polymorphonuclear neutrophil granulocytes (NEU), has been identified as a key player in lipid peroxidation in inflamed tissues. Considering that the expression of MPO was much higher in NASH than in the nonalcoholic fatty liver (NAFL) with steatosis, we designed a nanoparticle platform based on ultrasmall iron oxide (USIO) nanoparticles to realize MPO-sensitive NASH diagnosis. After modification of USIO nanoparticles with amphiphilic poly(ethylene glycol) (PEG) and conjugation with 5-hydroxytryptamine (5HT), a physiological substrate for MPO, the final nanocomposite (USIO-DA-PEG-5HT) revealed MPO-mediated aggregation at the inflammatory site of NASH. Meanwhile, the intrinsic T1-weighted magnetic resonance (MR) signal of dispersed USIO-DA-PEG-5HT nanoparticles diminishes, while the T2-weighted MR signal is amplified owing to the aggregation effect. These USIO-DA-PEG-5HT nanoprobes offer great potential for improving NASH MR imaging diagnostic accuracy and sensitivity compared to existing molecular MR contrast agents with a single imaging modality.

Construction of a DNA Nanoassembly Based on Spatially Ordered Recognition Elements for Inhibiting β-Amyloid Aggregation.

A β-amyloid (Aβ) aggregation process is a spontaneous process where the original random coil or helical structure changes into a regularly arranged β-sheet structure. The development of inhibitors with the features of low cost, high efficiency, and biosafety by targeting Aβ self-aggregation is significant for Alzheimer's disease treatment. However, the issues of low inhibition efficiency under low concentrations of inhibitors and biological toxicity are currently to be addressed. To resolve the above problems, a DNA nanoassembly (HCR-Apt) based on spatially ordered recognition elements was constructed by targeted disruption of Aβ ordered arrangement. It was discovered that HCR-Apt could inhibit effectively the fibrillation of Aβ40 monomers and oligomers at substoichiometric ratios. This may be due to orderly arrangement of aptamers in rigid nanoskeletons for enhancing the recognition interaction between aptamers and Aβ40. The strong interaction between HCR-Apt and Aβ40 limited the flexible conformational conversion of Aβ40 molecules, thereby inhibiting their self-assembly. Computational simulations and experimental analysis revealed the interactions of Apt42 with Aβ40, which explained different inhibition effects on the fibrillation of Aβ40 monomers and oligomers. Furthermore, the analysis of tyrosine intrinsic fluorescence spectra and surface plasmon resonance imaging showed that the interaction of HCR-Apt and Aβ40 was stronger than that of Apt42 and Aβ40. These findings contributed to establishing a promising method of boosting the recognition interaction by orderly arrangement of recognition elements. Taken together, this work is expected to provide a simple and efficient strategy for inhibiting Aβ aggregation, expanding aptamer's application potential in neurodegenerative diseases.

Multiband metamaterial emitters for infrared and laser compatible stealth with thermal management based on dissipative dielectrics

The modulation of thermal radiation in the infrared region is a highly anticipated method to achieve infrared sensing and camouflage. Here, a multiband metamaterial emitter based on the Al / SiO 2 / Al nanosandwich structure is proposed to provide new ideas for effective infrared and laser-compatible camouflage. By virtue of the intrinsic absorption and magnetic resonance property of lossy materials, the thermal radiation in the infrared region can be rationally modulated. The fabricated samples generally present low emissivity ( ε 3 – 5 μm = 0.21 , ε 8 – 14 μm = 0.19 ) in the atmospheric windows to evade infrared detection as well as high emissivity ( ε 5 – 8 μm = 0.43 ) in the undetected band for energy dissipation. Additionally, the laser camouflage is also realized by introducing a strong absorption at 10.6 μm through the nonlocalized plasmon resonance of the SiO 2 layer. Moreover, the fabricated emitter shows promising prospects in thermal management due to the good radiative cooling property that is comparable to the metallic Al material. This work demonstrates a multiband emitter based on the metasurface structure with compatible infrared-laser camouflage as well as radiative cooling properties, which is expected to pave new routes for the design of thermal radiation devices.

Functional connectivity of the visual cortex in chronic migraine before and after medication withdrawal therapy

Acute withdrawal of headache medication in chronic migraine patients with medication overuse may lead to a dramatic reduction in headache frequency and severity. However, the brain networks underlying chronic migraine and a favorable response to acute withdrawal are still poorly understood. The goal of the present study was to characterize the pattern of intrinsic magnetic resonance imaging (MRI) functional connectivity (FC) specific to chronic migraine and to identify changes in FC that characterize subjects with CM reverting to less frequent headaches. Subjects with chronic migraine (N = 99) underwent a resting-state functional MRI scan before and after three months of medication withdrawal therapy. In addition, we included four control groups who were scanned once: healthy participants (N = 27), patients with episodic migraine (N = 25), patients with chronic back pain (N = 22), and patients with clinical depression (N = 17). Using dual regression analysis, we compared whole-brain voxel-level functional connectivity with ten well-known resting-state networks between chronic migraine and control groups, and between responders to treatment (≥50 % reduction in monthly headache days) and non-responders (<50 % reduction), before and after treatment. Subjects with chronic migraine showed differences in FC with a number of RS-networks, most of which involved the visual cortex, compared with healthy controls. A comparison with patients with episodic migraine, chronic pain and depression showed differences in the same direction, suggesting that altered patterns of functional connectivity in chronic migraine patients could to some extent be explained by shared symptomatology with other pain, depression, or migraine conditions. A comparison between responders and non-responders indicated that effective withdrawal reduced FC with the visual cortex for responders. Interestingly, responders already differed in functional connectivity of the visual cortex at baseline compared with non-responders. Altogether, we show that chronic migraine and successful medication withdrawal therapy are linked to changes in the functional connectivity of the visual cortex. These neuroimaging findings provide new insights into the pathways underlying migraine chronification and its reversibility.

Cross-Junction Based Metasurface for Wideband 90° Polarization Rotation

In this work, an ultrathin subwavelength metasurface based on a cross-junction-inspired unit cell that exhibits efficient wideband polarization rotation is presented. This structure manipulates the polarization of the incident electromagnetic radiation in the transmission band. The proposed metasurface converts the incident linearly polarized waves into the orthogonal polarization over a fractional bandwidth of 9.6% with a maximum insertion loss of 0.65 dB. The detailed analysis of the structure’s inherent resonances and their origins are also presented with special emphasis on the intrinsic Fano resonances (FRs) of the proposed unit cell and their evolution by introducing structural asymmetry. A prototype of the proposed design is fabricated and characterized, and the results show very good agreement with numerical simulations.

Electrospinning of hierarchical carbon fibers with multi-dimensional magnetic configurations toward prominent microwave absorption

Hierarchical microstructures and synergistic dielectric-magnetic effect are expected to satisfy the improvement of microwave absorption, but still face considerable challenges. Herein, we employ the electrospinning strategy and thermal reduction engineering to fabricate hierarchical carbon fibers with multi-dimensional magnetic configurations, in which Ni spheres are embedded in carbon fibers and Co sheets are anchored on the surface of carbon fibers. The results indicate that abundant hetero-interfaces combined with electromagnetic synergy promote impedance characteristics and strengthen interfacial polarization, magnetic domains with multi-dimensional configurations contribute to magnetic loss by means of intrinsic ferromagnetic resonance and magnetic coupling, and unique hierarchical architectures result in multiple scatterings. As a result, the minimum reflection loss (RL,min) achieves a high value of −45.9 dB at 4 mm and the effective absorption bandwidth (EAB) reaches 5.9 GHz at a thickness of 2.8 mm. It is believed that this design concept opens up a novel strategy in fabricating multi-dimensional magnetic configurations and the absorbers with high-efficient absorption performance exhibit promising the potential in managing electromagnetic radiation.

Remote control of the recruitment and capture of endogenous stem cells by ultrasound for in situ repair of bone defects.

Stem cell-based tissue engineering has provided a promising platform for repairing of bone defects. However, the use of exogenous bone marrow mesenchymal stem cells (BMSCs) still faces many challenges such as limited sources and potential risks. It is important to develop new approach to effectively recruit endogenous BMSCs and capture them for in situ bone regeneration. Here, we designed an acoustically responsive scaffold (ARS) and embedded it into SDF-1/BMP-2 loaded hydrogel to obtain biomimetic hydrogel scaffold complexes (BSC). The SDF-1/BMP-2 cytokines can be released on demand from the BSC implanted into the defected bone via pulsed ultrasound (p-US) irradiation at optimized acoustic parameters, recruiting the endogenous BMSCs to the bone defected or BSC site. Accompanied by the daily p-US irradiation for 14 days, the alginate hydrogel was degraded, resulting in the exposure of ARS to these recruited host stem cells. Then another set of sinusoidal continuous wave ultrasound (s-US) irradiation was applied to excite the ARS intrinsic resonance, forming highly localized acoustic field around its surface and generating enhanced acoustic trapping force, by which these recruited endogenous stem cells would be captured on the scaffold, greatly promoting them to adhesively grow for in situ bone tissue regeneration. Our study provides a novel and effective strategy for in situ bone defect repairing through acoustically manipulating endogenous BMSCs.

Engineering a strong and stable ultraviolet chiroptical effect in a large-area chiral plasmonic shell.

Ultraviolet chiral metamaterials (UCM) are highly desired for their strong interaction with the intrinsic resonance of molecules and ability in manipulating the polarization state of high energy photons, but rarely reported to date due to their small feature size and complex geometry. Herein, we design and fabricate a kind of novel ultraviolet chiral plasmonic shell (UCPS) by combing the stepwise Al deposition and colloid-sphere assembled techniques. The cancellation effect originated from the disorder lattices of micro-domains in the colloid monolayer has been successfully overcome by optimizing the deposition parameters, and a strong CD signal of larger than 1 deg in the UV region is demonstrated both in simulation and experiment. This strong ultraviolet chiroptical resonances mainly come from the surface chiral lattice resonance mode, the whispering gallery mode and also the interaction between neighbor shells, and can be effectively tuned by changing structural parameters, for example, the sphere diameter, or even slightly increasing the deposition temperature in experiment. To improve the stability, the fabricated UCPSs are protected by N2 in the deposition chamber and then passivated by UV-ozone immediately after each deposition step. The formed UCPS show an excellent stability when exposing in the atmospheric environment. The computer-aided geometrical model, electromagnetic modes, and the tunable chiroptical resonance modes have been systematically investigated.

Valley-magnetophonon resonance for interlayer excitons

Heterobilayers consisting of MoSe2 and WSe2 monolayers can host optically bright interlayer excitons with intriguing properties such as ultralong lifetimes and pronounced circular polarization of their photoluminescence due to valley polarization, which can be induced by circularly polarized excitation or applied magnetic fields. Here, we report on the observation of an intrinsic valley-magnetophonon resonance for localized interlayer excitons promoted by invervalley hole scattering. It leads to a resonant increase of the photoluminescence polarization degree at the same field of 24.2 Tesla for H-type and R-type stacking configurations despite their vastly different excitonic energy splittings. As a microscopic mechanism of the hole intervalley scattering we identify the scattering with chiral TA phonons of MoSe2 between excitonic states mixed by the long-range electron hole exchange interaction.

Network resonance can be generated independently at distinct levels of neuronal organization.

Resonance is defined as maximal response of a system to periodic inputs in a limited frequency band. Resonance may serve to optimize inter-neuronal communication, and has been observed at multiple levels of neuronal organization. However, it is unknown how neuronal resonance observed at the network level is generated and how network resonance depends on the properties of the network building blocks. Here, we first develop a metric for quantifying spike timing resonance in the presence of background noise, extending the notion of spiking resonance for in vivo experiments. Using conductance-based models, we find that network resonance can be inherited from resonances at other levels of organization, or be intrinsically generated by combining mechanisms across distinct levels. Resonance of membrane potential fluctuations, postsynaptic potentials, and single neuron spiking can each be generated independently of resonance at any other level and be propagated to the network level. At all levels of organization, interactions between processes that give rise to low- and high-pass filters generate the observed resonance. Intrinsic network resonance can be generated by the combination of filters belonging to different levels of organization. Inhibition-induced network resonance can emerge by inheritance from resonance of membrane potential fluctuations, and be sharpened by presynaptic high-pass filtering. Our results demonstrate a multiplicity of qualitatively different mechanisms that can generate resonance in neuronal systems, and provide analysis tools and a conceptual framework for the mechanistic investigation of network resonance in terms of circuit components, across levels of neuronal organization.