Focal length switchable metalens based on vanadium dioxide.

A metalens is a flat lens that can control the phase of light so that dispersed light can be reconcentrated. This study devised a tunable metalens with a switchable focal length based on the phase transition properties of vanadium dioxide (V O 2). The unit structure comprises three layers from bottom to top: gold, polyimide, and two square resonant rings. The metalens can not only transform incident x-polarized waves into y-polarized waves but also achieve beam focusing simultaneously. The designed metalens achieves polarization conversion efficiency at an operating frequency of 0.8 THz. In the insulating state of V O 2, the beam focal point is at L=1914µm; in the metallic state, the wave converges at L=982µm, closely aligning with the predetermined focal length. By controlling external temperature, focal point switching can be achieved, making it highly versatile in practical applications.

A dual functional tunable terahertz metamaterial absorber based on vanadium dioxide.

A dual-functional switchable metamaterial absorber (MMA) based on vanadium dioxide (VO2), which achieves flexible switching between broadband absorption and four-band absorption by adjusting the VO2 conductivity, was proposed. The device has a broadband absorption function when VO2 is in the metal phase, and the conductivity is 3 × 105 S m-1. Numerical simulation shows that the absorption rate of the device reaches over 90% in the frequency range of 3.36-6.98 THz. The absorber exhibits polarization insensitivity and wide-angle absorption to transverse electric (TE) and transverse magnetic (TM) waves. When VO2 is in the insulator phase, and the conductivity is 3 × 102 S m-1, the device switches to a narrowband absorber with a band-efficient absorption function. Numerical simulation shows that the device has an absorption rate of 99.7% at 2.39 THz, 98.3% at 2.83 THz, 95.6% at 3.84 THz, and 96.1% at 4.61 THz. It can be used as a sensor with high sensitivity. In addition, to verify the absorption mechanism of the absorber, we introduced impedance matching theory to analyze the device. Finally, the influence of structural parameters on the performance of resonators was investigated. Through the joint action of multi-layer structures, the proposed MMA concentrates broadband and narrowband absorption functions on one device, achieving flexible switching between tasks without changing the structure. The switchable metamaterial absorber designed through simple tuning methods has broad application prospects in stealth technology and thermal emitters. It provides a wide range of ideas for the design of terahertz functional devices.

[Evaluation on monitoring effect of the electronic vaccine vial monitor label].

The cold chain safety of vaccines is a global issue. The electronic vaccine vial monitor (eVVM) label can monitor the temperature of vaccines in real time and provide "early warning" prompts. In order to comprehensively evaluate the monitoring efficiency of eVVM, this study selected 75 eVVM labels and distributed them with a total of 600 vaccine vial monitor (VVM) labels of four different types in different experimental environment (2-8℃, -20℃ and 40℃), and used a temperature recorder as "gold standard". The results showed that the accuracy of the eVVM labels and VVM labels in high temperature environment was as same as that of the temperature recorder ( P = 0.195). The accuracy of low temperature anomalies report and high temperature anomalies report of eVVM labels was 100%, which was better than those reported by VVM labels. Therefore, eVVM labels have high monitoring accuracy, which is suitable not only for ordinary environments, but also for severe temperature environments. It should be helpful for the improvement of the efficiency and accuracy of cold chain monitoring.

Genetic research and clinical analysis of deletional Chinese Gγ+(Aγδß)0 -thalassemia and Southeast Asian HPFH in South China.

Chinese Gγ+(Aγδß)0-thalassemia and SEA-HPFH are the most common types of ß-globin gene cluster deletion in Chinese population. The aim of the study was to analyze clinical features of deletional Chinese Gγ+(Aγδß)0-thalassemia and Southeast Asian hereditary persistence of fetal hemoglobin (SEA-HPFH) in South China. A total of 930 subjects with fetal hemoglobin (HbF) level ≥ 2% were selected on genetic research of Chinese Gγ+(Aγδß)0-thalassemia and SEA-HPFH. The gap polymerase chain reaction was performed to identify the deletions. One hundred cases of Chinese Gγ+(Aγδß)0-thalassemia were detected, including 90 cases of Chinese Gγ+(Aγδß)0/ßN-thalassemia, 7 cases of Chinese Gγ+(Aγδß)0 /ßN-thalassemia combined with α-thalassemia, 2 cases of Chinese Gγ+(Aγδß)0-thalassemia combined with ß-thalassemia, and 1 case of Chinese Gγ+(Aγδß)0-thalassemia combined with ß-gene mutation. One hundred nine cases of SEA-HPFH were detected, including 97 cases of SEA-HPFH/ßN, 9 cases of SEA-HPFH/ßN combined with α-thalassemia, 2 cases of SEA-HPFH combined with ß-thalassemia, and 1 case of SEA-HPFH combined with ß-gene mutation. Statistical analysis indicates significant differences in MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin), and HbA2 and HbF levels between Chinese Gγ+(Aγδß)0-thalassemia heterozygotes and SEA-HPFH heterozygotes (P < 0.001). There are statistical differences in hematological parameters between them. Clinical phenotypic analysis can provide guidance for genetic counseling and prenatal diagnosis.