Simultaneous manipulation of electromagnetic and elastic waves via glide symmetry phoxonic crystal waveguides

A phoxonic crystal waveguide with the glide symmetry is designed, in which both electromagnetic and elastic waves can propagate along the glide plane at the same time. Due to the band-sticking effect, super-cell bands of the waveguide degenerate in pairs at the boundary of the Brillouin zone, causing the appearance of gapless guided-modes in the bandgaps. The gapless guided-modes are single-modes over a relatively large frequency range. By adjusting the magnitude of the glide dislocation, the edge bandgaps of the guided-modes can be further adjusted, so as to achieve photonic and phononic single-mode guided-bands with relatively flat dispersion relationship. In addition, there exists acousto-optic interaction in the cavity constructed by the glide plane. The proposed waveguide has potential applications in the design of novel optomechanical devices.Comment: 16 pages, 9 figure

Manipulating strong coupling between exciton and quasi-bound states in the continuum resonance

Strong coupling exhibits unique ability to preserve quantum sates between light and matter, which is essential for the development of quantum information technology. To explore the physical mechanism behind this phenomenon, we employ the tight-binding method for expanding the temporal coupled-mode theory, with the absorption spectrum formula of coupled system directly obtained in an analytical way. It reveals all the physical meaning of parameters defined in our theory, and shows how to tailor lineshapes of the coupled systems. Here, we set an example to manipulate the strong coupling in a hybrid structure composed of excitons in monolayer WS$_2$ and quasi-bound states in the continuum supported by the TiO$_2$ nanodisk metasurfaces. The simulated results show that a clear spectral splitting appeared in the absorption curve, which can be controlled by adjusting the asymmetric parameter of the nanodisk metasurfaces and well fitted through our theoretical predictions. Our work not only gives a more comprehensive understanding of such coupled systems, but also offers a promising strategy in controlling the strong light-matter coupling to meet diversified application requests

Non-Foster Impedance Wideband Matching Technique for Electrically Small Active Antenna

This paper investigates a non-Foster wideband circuit matching technique for an electrically small antenna (ESA). By introducing a negative impedance convertor into an active network, the active network can obtain an equivalent input gain at input port to improve gain, sensitivity and output ratio of signal to noise. In addition, it also increases the effective height of active antenna. The experimental results have verified the proposed method by using a 100 KHz-30 MHz wideband active receiving monopole antenna

Effects of Personalized Aerobic-Exercise and Resistance-Training Prescriptions on College Students with Anxiety During the COVID-19

The COVID-19 pandemic has seriously increased anxiety prevalence among the public, including Chinese college students. However, many exercises cannot be performed as usual under the stay-at-home order. The purpose of this study was to evaluate and compare the effect of personalized individual aerobic-exercise and resistance-training prescriptions on anxiety in college students during the COVID-19. This was a 12-week three-arm randomized control trial using the intention-to-treat principle. Sixty-six college students with anxiety were recruited and randomized into aerobic-exercise (AE), resistance-training (RT), and health-education group (HE). AE and RT groups also received health education. Measures on anxiety and physical activity included Zung Self-Rating Anxiety Scale (SAS), Chinese College Students Mental Health Scale - Anxiety Subscale (CCSMHS-AS) and International Physical Activity Questionnaire-Short Form (IPAQ-SF). All data were collected at the baseline, 4, 8, 12 weeks and 4-week post-intervention. All participants completed the intervention and measurements. The mean (SD) of SAS, CCSMHS-AS score and physical activity was 56.36 (5.63), 19.27 (4.56), 1306.57 (1421.19) (met-min/week). After the intervention, 78.79% of anxiety participants improved from anxiety to “normal”. Participants in all groups showed a statistically and clinically significant improvement after 12-week intervention (p \u3c 0.001). Moreover, such improvement was well-maintained in RT and HE group as there were no significant differences in SAS and CCSMHS-AS at 4-week post-intervention compared to 12 weeks (p \u3e 0.05). However, the SAS score of participants in AE group showed a significant increase during the 4 weeks after intervention (p \u3c 0.05). No significant differences were observed in the effect of AE and RT on anxiety at each time-point (p \u3e 0.05). PA of participants in AE and RT group represented a significant improvement at 4-week post-intervention compared to baseline (p \u3c 0.01). Personalized individual aerobic-exercise and resistance-training combined with health-education resulted in a similar effect on reducing anxiety and improving physical activity, and the effect was better than health education alone. Furthermore, the effect of resistance-training and health-education on reducing anxiety was more stable than that of aerobic-exercise. We recommended 45- to 60-minute home-based individual exercise (including 30- to 40-minute main exercise) with progressive moderate-to-high intensity, 3 times/week for at least 12 weeks for those students with anxiety during the COVID-19 pandemic

Enhancing Faraday and Kerr rotations based on toroidal dipole mode in an all-dielectric magneto-optical metasurface

The magneto-optical Faraday and Kerr effects are widely used in modern optical devices. In this letter, we propose an all-dielectric metasurface composed of perforated magneto-optical thin films, which can support the highly confined toroidal dipole resonance and provide full overlap between the localized electromagnetic field and the thin film, and consequently enhance the magneto-optical effects to an unprecedented degree. The numerical results based on finite element method show that the Faraday and Kerr rotations can reach -13.59${\deg}$ and 8.19${\deg}$ in the vicinity of toroidal dipole resonance, which are 21.2 and 32.8 times stronger than those in the equivalent thickness of thin films, respectively. In addition, we design an environment refractive index sensor based on the resonantly enhanced Faraday and Kerr rotations, with sensitivities of 62.96 nm/RIU and 73.16 nm/RIU, and the corresponding maximum figures of merit 132.22${\deg}$/RIU and 429.45${\deg}$/RIU, respectively. This work provides a new strategy for enhancing the magneto-optical effects at nanoscale, and paves the way for the research and development of magneto-optical metadevices such as sensors, memories, and circuits

On the use of an explicit chemical mechanism to dissect peroxy acetyl nitrate formation.

Peroxy acetyl nitrate (PAN) is a key component of photochemical smog and plays an important role in atmospheric chemistry. Though it has been known that PAN is produced via reactions of nitrogen oxides (NOx) with some volatile organic compounds (VOCs), it is difficult to quantify the contributions of individual precursor species. Here we use an explicit photochemical model--Master Chemical Mechanism (MCM) model--to dissect PAN formation and identify principal precursors, by analyzing measurements made in Beijing in summer 2008. PAN production was sensitive to both NOx and VOCs. Isoprene was the predominant VOC precursor at suburb with biogenic impact, whilst anthropogenic hydrocarbons dominated at downtown. PAN production was attributable to a relatively small class of compounds including NOx, xylenes, trimethylbenzenes, trans/cis-2-butenes, toluene, and propene. MCM can advance understanding of PAN photochemistry to a species level, and provide more relevant recommendations for mitigating photochemical pollution in large cities

Phase-change nonlocal metasurfaces for dynamic wavefront manipulation

Recent advances in nonlocal metasurfaces have enabled unprecedented success in shaping the wavefront of light with spectral selectivity, offering new solutions for many emerging nanophotonics applications. The ability to tune both the spectral and spatial properties of such a novel class of metasurfaces is highly desirable, but the dynamic nonvolatile control remains elusive. Here, we demonstrate active narrowband wavefront manipulation by harnessing quasi-bound states in the continuum (quasi-BICs) in phase-change nonlocal metasurfaces. The proof-of-principle metasurfaces made of Sb$_2$S$_3$ allow for nonvolatile, reversible, and tunable spectral control over wavefront and switchable spatial response at a given wavelength. The design principle mainly builds upon the combination of the geometry phase of quasi-BICs and the dynamic tunability of phase-change meta-atoms to tailor the spatial response of light at distinct resonant wavelengths. By tuning the crystallization level of Sb$_2$S$_3$ meta-atoms, the dynamic nonlocal wavefront-shaping functionalities of beam steering, 1D, and 2D focusing are achieved. Furthermore, we demonstrate tunable holographic imaging with active spectral selectivity using our phase-change nonlocal metasurface. This work represents a critical advance towards developing integrated dynamic nonlocal metasurface for future augmented and virtual reality wearables

Galectin-9 contributes to the pathogenesis of atopic dermatitis via T cell immunoglobulin mucin-3

BackgroundAtopic dermatitis (AD), a common type 2 inflammatory disease, is driven by T helper (TH) 2/TH22polarization and cytokines.Galectin-9 (Gal-9), via its receptor T cell immunoglobulin- and mucin-domain-containing molecule-3 (TIM-3), can promote TH2/TH22 immunity. The relevance of this in AD is largely unclear.ObjectivesTo characterize the role of TIM-3 and Gal-9 in the pathogenesis of AD and underlying mechanisms.MethodsWe assessed the expression of Gal-9 and TIM-3 in 30 AD patients, to compare them with those of 30 healthy controls (HC) and to explore possible links with disease features including AD activity (SCORAD), IgE levels, and circulating eosinophils and B cells. We also determined the effects of Gal-9 on T cells from the AD patients.ResultsOur AD patients had markedly higher levels of serum Gal-9 and circulating TIM-3-expressing TH1 and TH17 cells than HC. Gal-9 and TIM-3 were linked to high disease activity, IgE levels, and circulating eosinophils and/or B cells. The rates of circulating TIM-3-positive CD4+ cells were positively correlated with rates of TH2/TH22 cells and negatively correlated with rates of TH1/TH17 cells. Gal-9 inhibited the proliferation and induced the apoptosis of T cells in patients with AD, especially in those with severe AD.ConclusionOur findings suggest thatGal-9, via TIM-3, contributes to the pathogenesis of AD by augmenting TH2/TH22 polarization through the downregulation of TH1/TH17immunity. This makes Gal-9 and TIM-3 interesting to explore further, as possible drivers of disease and targets of novel AD treatment

A Novel Tunable Triple-Band Left-Handed Metamaterial

A novel tunable triple-band left-handed metamaterial (LHM) composed of a single-loop resonator (SLR) and a variable capacitor-loaded short wire pair (CL-SWP) printed on both sides of a substrate is presented in this paper. The CL-SWP-based metamaterial (MTM) is a novel single-sided LHM. It is theoretically analyzed capable of extracting tunable negative permeability and a wide-band negative permittivity. We ran simulations for the CL-SWP-based MTM, the SLR-based MTM, and the proposed LHM. Together with the measured results, it is identified that this novel LHM exhibits a tunable triple-band left-handed (LH) property. With the increase of the loaded capacitance, one LH band is relatively stable, while the other two are moving towards lower frequencies with their bandwidth getting wider and narrower, respectively. The surface current density distributions indicate that the first LH band is mainly decided by the SLR, one of the rest 2 LH bands is mainly decided by the CL-SWP, and the other one is decided by the SLR and CL-SWP together