Flexible Terahertz Metasurface Absorbers Empowered by Bound States in the Continuum.

Terahertz absorbers are crucial to the cutting-edge techniques in the next-generation wireless communications, imaging, sensing, and radar stealth, as they fundamentally determine the performance of detectors and cloaking capabilities. It has long been a pressing task to find absorbers with customizable performance that can adapt to various environments with low cost and great flexibility. Here, perfect absorption empowered by bound states in the continuum (BICs) is demonstrated, allowing for the tailoring of absorption coefficient, bandwidth, and field of view. The one-port absorbers are interpreted using temporal coupled-mode theory highlighting the dominant role of BICs in the far-field radiation properties. Through a thorough investigation of BICs from the perspective of lattice symmetry, the radiation features of three BIC modes are unraveled using both multipolar and topological analysis. The versatile radiation capabilities of BICs provide ample freedom to meet specific requirements of absorbers, including tunable bandwidth, stable performance in a large field of view, and multiband absorption using a thin and flexible film without extreme geometric demands. These findings offer a systematic approach to developing optoelectronic devices and demonstrate the significant potential of BICs for optical and photonic applications, which will stimulate further studies on terahertz photonics and metasurfaces.

Terahertz polarization conversion and asymmetric transmission based on a liquid crystal integrated EIT metasurface.

We experimentally demonstrate a liquid crystal (LC)-integrated EIT metasurface for active THz polarization conversion and asymmetric transmission. By controlling the LC orientation under static magnetic field anchoring and an adjustable electric field, the device realizes the active control from the OFF state to the ON state, corresponding to the orthogonal polarization excitation modes of the EIT metasurface. Furthermore, based on the different polarization responses at forward and backward incidences, we achieve asymmetric transmission at the EIT peak and two nearby resonances, with its isolation actively manipulated by the external electric field. This study on dynamic polarization conversion and asymmetric transmission by a LC-integrated metasurface offers a promising route for active THz devices, applicable to THz communication, switching, and sensing systems.

Terahertz topological photonic crystals with dual edge states for efficient routing.

Topological photonic crystals with robust pseudo-spin and valley edge states have shown promising and wide applications in topological waveguides, lasers, and antennas. However, the limited bandwidth and intrinsic coupling properties of a single pseudo-spin or valley edge state have imposed restrictions on their multifunctional applications in integrated photonic circuits. Here, we propose a topological photonic crystal that can support pseudo-spin and valley edge states simultaneously in a single waveguiding channel, which effectively broadens the bandwidth and enables a multipath routing solution for terahertz information processing and broadcasting. We show that distorted Kekulé lattices can open two types of bandgaps with different topological properties simultaneously by molding the inter- and intra-unit cell coupling of the tight-binding model. The distinct topological origins of the edge states provide versatile signal routing paths toward free space radiation or on-chip self-localized edge modes by virtue of their intrinsic coupling properties. Such a powerful platform could function as an integrated photonic chip with capabilities of broadband on-chip signal processing and distributions that will especially benefit terahertz wireless communications.

Moderate selenium mitigates hand grip strength impairment associated with elevated blood cadmium and lead levels in middle-aged and elderly individuals: insights from NHANES 2011-2014.

Background: Selenium (Se) has been reported to have an antagonistic effect on heavy metals in animals. Nevertheless, there is a lack of epidemiological research examining whether Se can mitigate the adverse effects of cadmium (Cd) and lead (Pb) on hand grip strength (HGS) in middle-aged and elderly individuals. Methods: This study used data from the 2011-2014 National Health and Nutrition Examination Survey (NHANES). HGS measurements were conducted by trained examiners with a dynamometer. Concentrations of Se, Cd, and Pb in blood were determined via inductively coupled plasma mass spectrometry. We employed linear regression, restricted cubic splines, and quantile g-computation (qgcomp) to assess individual and combined associations between heavy metals and HGS. The study also explored the potential influence of Se on these associations. Results: In both individual metal and multi-metal models adjusted for confounders, general linear regression showed Se's positive association with HGS, while Cd and Pb inversely related to it. At varying Se-Cd and Se-Pb concentrations, high Se relative to low Se can attenuate Cd and Pb's HGS impact. An inverted U-shaped correlation exists between Se and both maximum and combined HGS, with Se's benefit plateauing beyond approximately 200 µg/L. Stratified analysis by Se quartiles reveals Cd and Pb's adverse HGS effects diminishing as Se levels increase. Qgcomp regression analysis detected Se alleviating HGS damage from combined Cd and Pb exposure. Subsequent subgroup analyses identified the sensitivity of women, the elderly, and those at risk of diabetes to HGS impairment caused by heavy metals, with moderate Se supplementation beneficial in mitigating this effect. In the population at risk for diabetes, the protective role of Se against heavy metal toxicity-induced HGS reduction is inhibited, suggesting that diabetic individuals should particularly avoid heavy metal-induced handgrip impairment. Conclusion: Blood Cd and Pb levels are negatively correlated with HGS. Se can mitigate this negative impact, but its effectiveness plateaus beyond 200 µg/L. Women, the elderly, and those at risk of diabetes are more vulnerable to HGS damage from heavy metals. While Se supplementation can help, its protective effect is limited in high diabetes risk groups.

First Report of Alfalfa Anthracnose Caused by Colletotrichum americae-borealis in Xinjiang, China.

Alfalfa (Medicago sativa L.) is widely planted in the world as one of the most important leguminous forage crops, and it is also the first choice of forage crops for animal feed in Xinjiang. In June 2018, alfalfa plants with typical anthracnose symptoms were observed in 75% of alfalfa fields in Hutubi County, Xinjiang, China. The disease usually occurred in alfalfa fields that had been planted for more than 2 years and was distributed in patches in the field. The incidence rate ranged from 7.5% to 53%, and the fatality rate ranged from 0 to 3%. Greater incidence was observed in fields with older stands. At the early stage of disease, pale brown prismatic or oval sunken lesions with dark brown to black edges were observed at the base of the stem of alfalfa plants. As the symptoms progressed, lesions on stems turned necrotic, and the center of the lesion became gray-white with black dots. In severe cases, the lesion expanded around the stem, causing the upper part of the stem to break off, or wilt and die. Twenty plant stem sections with typical symptoms were sampled and surface-sterilized with 75% ethanol for 30 s and 1% NaClO for 1 min, rinsed in sterilized distilled water, dried on sterilized filter paper for 45 s, placed on potato dextrose agar (PDA), and incubated in the dark at 25°C for 7 days. A fungus was frequently isolated from the surface-sterilized segments, and the colonies of this fungus were white and flat at first, and later the center of colonies became pale brown with black microsclerotia (2.0~3.2 mm. n = 30) and white or brown acervuli (1.0~1.8 mm. n = 30). A large number of conidia and setae spread from ruptured microsclerotia under microscopy. Conidia (n = 40) were hyaline, smooth-walled, straight, aseptate, cylindrical to fusoid, both tips acute to round, 13.7 to 19.5×3.0 to 4.5 µm . Setae (n = 30) were dark brown to black, smooth-walled, 3~6 septate, straight or slightly curved, 66.9~185.1 µm long, tip round and base swollen, 3.9~5.2 µm width. Sometimes setae formed directly on hyphae or brown acervuli. Colony and conidia morphology were similar to the description of Colletotrichum americae-borealis (Damm et al. 2014; Lyu et al. 2020). DNA was extracted from fresh mycelia of three representative isolates (R11, R12 and R13) and the ITS, ACT, CHS-1 and HIS3 genes of three isolates were amplified and sequenced using the primers described previously by Damm et al. (2014). The sequences of three isolates were identical, and twelve aligned sequences from three representative isolates were deposited in GenBank (MT877442, MT877443 and MT877444 for ITS, MW854350, MW854351 and MW854352 for ACT, MW270930, MW270931 and MW270107 for CHS-1, MW854347, MW854348 and MW854349 for HIS3). Sequence analysis revealed that the ITS, ACT, CHS-1 and HIS3 sequences of three representative isolates were shared 99% (355/356 bp for HIS3) to 100% (550/550 bp for ITS, 261/261 bp for ACT, 221/221 bp for CHS-1) identities to each sequence of an American strain (CBS 136232) of C. americae-borealis from alfalfa in GenBank (NR160760 for ITS, KM105434 for ACT, KM105294 for CHS-1, KM105364 for HIS3). Four phylogenetic trees were constructed by the Mrbayes method (Damm et al. 2014), and the result showed that three representative isolates grouped with C. americae-borealis. Combined with morphological observation and molecular biological identification, the pathogen was identified as C. americae-borealis. Pathogenicity tests were executed twice on alfalfa seedlings in a greenhouse. Pots containing ten 40-day old seedlings (Xinjiang daye) were sprayed with a 100 ml of condial suspension (10^6 condia/ml) of R11. Control pots were sprayed with 100 ml of sterile distilled water. Two weeks after inoculation under greenhouse conditions (25 ± 2°C, 12-h photoperiod, 85% humidity), brown spots and necrotic lesions developed on the stem of inoculated alfalfa seedlings, which were similar to disease plants in fields, and C. americae-borealis was reisolated from symptomatic tissue. The control seedlings remained symptomless. Anthracnose caused by C. americae-borealis was reported on alfalfa in the north region of America and Iran (Damm et al. 2014; Alizadeh et al. 2015), as well as Gansu, Inner Mongolia, Yunnan and Heilongjiang Province of China ( Xu. 2019; zhang et al. 2020) . To our knowledge, this is the first report of Colletotrichum americae-borealis causing Alfalfa Anthracnose in Xinjiang, China. This finding can provide an important reference for understanding the distribution and control of this disease.

Hospital use in survivors of transient ischaemic attack compared with survivors of stroke in central China: a nested case-control study.

OBJECTIVES: There is a lack of knowledge regarding post-discharge hospitalisation utilisation after transient ischaemic attack (TIA) in China. The aim of this study is to quantify rehospitalisation use in survivors of TIA compared with their own previous hospital use and matched survivors of stroke. DESIGN: Nested case-control study of electronic medical records datasets. SETTING: 958 hospitals in Henan, China, from July 2012 to December 2015. PARTICIPANTS: In total, 4823 survivors of stroke were matched to the TIA cohort (average age: 64.5 years; proportion of men: 48.4%) at a 1:1 ratio. All subjects with an onset of stroke/TIA were recorded with a 1-year look-back and follow-up. OUTCOME MEASURES: Adjusted difference-in-differences (DID) values in 1-year hospital lengths of stay (LOSs) and readmission within 7, 30 and 90 days. RESULTS: There was an increase in hospital admissions in survivors of TIA in the year after the index hospitalisation compared with the prior year. Of the 2449 rehospitalisation events that occurred during the first year after TIA, stroke (20.6%) was the most common reason for rehospitalisation. There was no difference in the stroke-specific readmission rates between the TIA and stroke cohorts (p=0.198). The TIA cohort had fewer readmissions within 30 days and 90 days after all-cause discharge compared with the controls. The corresponding covariate-adjusted DID values were -3.5 percentage points (95% CI -5.3 to -1.8) and -4.5 (95% CI -6.5 to -2.4), respectively. A similar trend was observed in the 1-year LOS. In the stratified analysis, the DID reductions were not significant in patients with more comorbidities or in rural patients. CONCLUSIONS: Compared with survivors of stroke, survivors of TIA use fewer hospital resources up to 1 year post-discharge. Greater attention to TIAs among patients with more comorbidities and rural patients may provide an opportunity to reduce hospital use.

Tunable Nanosensor Based on Fano Resonances Created by Changing the Deviation Angle of the Metal Core in a Plasmonic Cavity.

In this paper, a type of tunable plasmonic refractive index nanosensor based on Fano resonance is proposed and investigated. The sensor comprises a metal-insulator-metal (MIM) nanocavity with a center-deviated metal core and two side-coupled waveguides. By carefully adjusting the deviation angle and distance of the metal core in the cavity, Fano resonances can be obtained and modulated. The Fano resonances can be considered as results induced by the symmetry-breaking or geometric effect that affects the field distribution intensity at the coupling region between the right waveguide and the cavity. Such a field-distribution pattern change can be regarded as being caused by the interference between the waveguide modes and the cavity modes. The investigations demonstrate that the spectral positions and modulation depths of Fano resonances are highly sensitive to the deviation parameters. Furthermore, the figure of merit (FOM) value is calculated for different deviation angle. The result shows that this kind of tunable sensor has compact structure, high transmission, sharp Fano lineshape, and high sensitivity to the change in background refractive index. This work provides an effective method for flexibly tuning Fano resonance, which has wide applications in designing on-chip plasmonic nanosensors or other relevant devices, such as information modulators, optical filters, and ultra-fast switches.

Wide-angle broadband terahertz metamaterial absorber with a multilayered heterostructure.

In this paper, a wide-angle broadband perfect absorber is composed of a periodical metamaterial heterostructure. The structure is designed according to the concept that the metamaterial absorber's resonant frequency range can be manipulated by adjusting the filling factor of a bi-insulator heterostructure. The calculated results reveal that the four-layer herostructure has four perfect absorption peaks at the range of the terahertz frequency band. The related absorption bandwidth is 300 GHz and the average absorptivity is 98.6%. At the same time, the structure is insensitive to the incident angle.

[Sero-prevalence and associated risk factors on hepatitis C in Maqiao township, Henan province of China].

OBJECTIVE: To describe the prevalence and risk factors of hepatitis C virus (HCV) occurred in Henan province, at the end of 2011. METHODS: Five villages round Maqiao township, including 5187 residents, were selected for the study. Five-milliliter-blood was drawn from every one of the interviewee. Clinical data including age, gender and anti-HCV antibody was recorded. Patients with positive antibodies against HCV were tested for HCV RNA. RESULTS: A total number of 5187 people from five villages were studied, with age span from 1 to 97. The average age was 48 years and the sex ratio was 1:1.34. The anti-HCV result showed that the prevalence was 2.27%, with 1-9 age group the lowest (1.55%) and the ≥ 50 year-olds the highest (4.93%). Different villages seemed to have significant differences on the prevalence of HCV, with the highest as 8.68% and the lowest as 0.55%. Under risk factors analysis and distance-infection rates linear regression analysis, data showed that the prevalence might have correlated to the behavior of a certain family-run clinic. RESULTS: from multivariate analysis indicated that factors as intravenous dropping, intravenous injection and the use of surgery/endoscope were associated with the HCV infection in this village. CONCLUSION: Although the public health care system had been developed for more than ten years, iatrogenic infection was yet responsible for the infection of HCV patients in the rural areas of China that called for further attention paid to the system.