Multiple toroidal dipole Fano resonances from quasi-bound states in the continuum in an all-dielectric metasurface.

In this paper, a highly sensitive sensor consisting of a silicon nanorod and symmetric rings (SNSR) is presented. Theoretically, three Fano resonances with high Q-factors are excited in the near-infrared range by breaking the symmetry structure based on quasi-bound states in the continuum (Q-BICs). The electromagnetic near-field analysis confirms that the resonances are mainly controlled by toroidal dipole (TD) resonance. The structure is optimized by adjusting different geometrical parameters, and the maximum Q-factor of the Fano resonances can reach 7427. To evaluate the sensing performance of the structure, the sensitivity and the figure of merit (FOM) are calculated by adjusting the environmental refractive index: the maximum sensitivity of 474 nm/RIU and the maximum FOM of 3306 RIU-1. The SNSR can be fabricated by semiconductor-compatible processes, which is experimentally evaluated for changes in transmission spectra at different solution concentrations. The results show that the sensitivity and the Q-factor of the designed metasurface can reach 295 nm/RIU and 850, while the FOM can reach 235 RIU-1. Therefore, the metasurface of SNSR is characterized by high sensitivity and multi-wavelength sensing, which are current research hotspots in the field of optics and can be applied to biomedical sensing and multi-target detection.

High-Performance Refractive Index and Temperature Sensing Based on Toroidal Dipole in All-Dielectric Metasurface.

This article shows an all-dielectric metasurface consisting of "H"-shaped silicon disks with tilted splitting gaps, which can detect the temperature and refractive index (RI). By introducing asymmetry parameters that excite the quasi-BIC, there are three distinct Fano resonances with nearly 100% modulation depth, and the maximal quality factor (Q-factor) is over 104. The predominant roles of different electromagnetic excitations in three distinct modes are demonstrated through near-field analysis and multipole decomposition. A numerical analysis of resonance response based on different refractive indices reveals a RI sensitivity of 262 nm/RIU and figure of merit (FOM) of 2183 RIU-1. This sensor can detect temperature fluctuations with a temperature sensitivity of 59.5 pm/k. The proposed metasurface provides a novel method to induce powerful TD resonances and offers possibilities for the design of high-performance sensors.

[Experimental study of the characteristics of renal blood flow with contrast ultrasound].

OBJECTIVE: To study the characteristics of renal blood flow with contrast ultrasound. METHODS: The examination of the renal ultrasonography was performed in 10 dogs after intravenous injection of Quanfuxian (a contrast agent consisting of C3F8 microbubbles). RESULTS: Contrast visualization appeared in the renal cortex and then in the outer to inner medulla at the baseline level after administration of the contrast agent. Notable differences in the values of microvascular volume (A, which was 120.3 in the corted vs 110.8 in the medulla, P>0.05), microcirculatory flow velocity (beta, which was 1.39 in the corted vs 0.54 in the medulla, P<0.05), and microcirculatory flow rate (A x beta, 167.4 in the corted vs 59.5 in the medulla, P<0.05) were found between the corted and the medulla, with also marked difference between the the corted-to-the medulla ratios of beta and A (0.612 vs 0.078, P<0.05). CONCLUSION: Contrast ultrasound of the kidney provides a useful means of renal circulatory flow study.

[Quantitative evaluation of canine renal blood flow with contrast-enhanced ultrasound].

OBJECTIVE: To evaluate the accuracy of contrast-enhanced ultrasound (CEU) in renal blood flow quantification. METHODS: Regional renal perfusion was quantified with CEU in 10 dogs at the baseline level and after treatment with 3 doses of dopamine (3, 8 and 16 mg.kg(-1).min(-1)), and renal arterial flow (RAF) was measured with ultrasonic flow probes deployed directly on the renal artery simultaneously. Normalized RAF was calculated as RAF divided by renal weight (ml.min(-1).g(-1)). RESULTS: Compared with the baseline level, a progressive increase in RAF was induced by dopamine treatment at the doses of 3 and 8 mg.kg(-1).min(-1) (P<0.05), but at a higher dose of 16 mg.kg(-1).min(-1), the increment in RAF was reduced in comparison with that with the two lower doses (P<0.05). The same changes in cortical nutrient blood flow derived from CEU were observed. Significant positive correlation was found between normalized RAF and CEU-derived cortical nutrient blood flow (y=39.8x + 44.3, r=0.88, P<0.001). CONCLUSION: CEU can be used to accurately quantify renal blood flow in dogs.

[Effects of a novel recombinant polypeptide from the sea anemone Anthopleura sp. on left ventricular function in dogs with acute cardiac insufficiency].

OBJECTIVE: To observe the effects of recombinant hk2a, a novel neurotoxin from the sea anemone Anthopleura sp., on left ventricular function of dogs with acute cardiac insufficiency. METHODS: Canine models of acute cardiac insufficiency were established by rapid ventricular pacing, in which the left ventricular ejection fraction (LVEF) was measured by Acuson ultrasound systems (Sequoia 512) at 0, 5, 15, 30 and 60 min, respectively, after intravenous injection of 30 microg/kg recombinant hk2a. The response of the canine models to hk2a treatments was observed in comparison with that of the dogs treated with Cedilanid (as positive control) and saline (as negative control). RESULTS: Intravenous injection of recombinant hk2a caused an immediate and significant increase in LVEF in the canine models of acute cardiac insufficiency (P<0.05), and the effect maintained for more than 30 min without significant effect on heart rate. Recombinant hk2a possessed such merits as quicker onset and greater potency in comparison with Cedilanid. CONCLUSION: Recombinant hk2a may significantly increase LVEF of the dogs with acute cardiac insufficiency.

[Effects of blood lipid levels on ST-T segment in asymptomatic hypertensive patients].

OBJECTIVE: To identify the factors affecting ST-T segment in asymptomatic hypertensive patients. METHODS: The asymptomatic patients with hypertension were divided into abnormal ST-T group (n=28) and normal ST-T group (n=20), in whom the serum levels of glucose, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), very-low-density lipoprotein cholesterol (VLDL) were measured. RESULTS: Compared with patients with normal ST-T segment, patients with abnormal ST-T segment had significantly higher serum levels of TC, but significantly lower HDL. The serum levels of glucose, TG, LDL, VLDL differed little between the 2 groups of patients. CONCLUSION: In asymptomatic patients with hypertension, higher serum TC level may cause or worsen ischemic myocardial damage, for which HDL plays a protective role.

Preventive effect of crocin on osteoporosis in an ovariectomized rat model.

The purpose of this study was to investigate the therapeutic effects of crocin on ovariectomy-induced osteoporosis in rats. Female Sprague-Dawley rats were randomly assigned to a sham-operated group (sham) and five ovariectomy (OVX) subgroups, that is, OVX with vehicle (OVX), OVX with 17ß-estradiol (E 2, 25 µg/kg/day), and OVX with graded crocin doses (5, 10, or 20 mg/kg/day). Daily oral administration of E 2 or crocin started 4 weeks after OVX and lasted for 16 weeks. Our results showed that crocin dose-dependently inhibited the BMD reduction of L4 vertebrae and femurs caused by OVX and prevented the deterioration of trabecular microarchitecture, which were accompanied by a significant decrease in skeletal remodeling as evidenced by the lower levels of bone turnover markers. Furthermore, crocin reversed the oxidative stress status in both serum and bone tissue. The present study indicates that the administration of crocin at higher doses over a 16-week period can prevent OVX-induced osteoporosis in rats without hyperplastic effects on the uterus, which may, at least partially, be attributed to crocin's antioxidative property. In brief, crocin is a natural alternative for postmenopausal osteoporosis treatment in elderly women.