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The branched fructooligosaccharides ABW90-1 and ABW50-1 from Achyranthes bidentatawith potent antiosteoporosis activities have been synthesized for the first time. The synthetic approach highlights the following features: (1) 6-O-picoloyl-directed β-d-fructofuranosylation via a hydrogen-bond-mediated aglycone delivery strategy for the highly stereoselective constructions of β-(2 → 6)-d-fructofuranosidic linkages and β-(2 → 1)-d-fructofuranosidic linkages in the internal positions under the reaction conditions (DBDMH, −20 °C, CH2Cl2) and (2) the reaction conditions (DBDMH, −78 °C to −35 °C, toluene) for highly stereoselective formations of β-(2 → 1)-d-fructofuranosidic linkages in the terminal positions.

In this article, we introduce a balanced broadband mu-near-zero (MNZ) loop antenna, which is designed for Wi-Fi 6/6E applications in full metal housing tablet computers. Different from the previous MNZ segmented loop antenna with the single $0^{\text {th}}$ mode, the higher order $1^{\text {st}}$ / $2^{\text {nd}}$ / $3^{\text {rd}}$ modes are also included for broadband purpose. By adjusting the effective permeability through the distributed capacitors in the proposed antenna, the electrical lengths of the $0^{\text {th}}$ / $1^{\text {st}}$ / $2^{\text {nd}}$ / $3^{\text {rd}}$ modes are reasonably stretched. This allows for multimode synergy in a single MNZ loop located in full metal housing computers. Therefore, the proposed MNZ loop antenna, with a planar structure of $6.8\times 45.4$ mm2, exhibits a broad bandwidth with $S_{11} \lt -6$ dB from 4.5 to 7.5 GHz, covering Wi-Fi 6/6E bands. As another merit for practical applications, this broadband MNZ loop antenna is also balanced with less current on the motherboard, performing excellent robustness against changes in tablet computer sizes or affecting by hands. The proposed MNZ loop antenna, with its multiple modes, offers valuable insights for the development of broadband and robust antennas in full metal housing devices.

In chemical and biological analysis, different substances have different requirements for RI detection. In this article, we propose and experimentally validate a molybdenum disulfide (MoS2)-modulated surface plasmon resonance (SPR) sensor. Due to the high effective refractive index (RI) of MoS2, the detection accuracy of the sensor after MoS2 modulation is good. The numerical simulation results verify that the MoS2 film has a good improvement effect on the performance of fiber sensing. The sensor is fabricated by coating a silver film and a MoS2 film on a photonic crystal fiber (PCF) using a magnetron sputtering method. First, the optimal sensing length and sputtering time of the silver film are determined experimentally, and the MoS2 film is coated on the optimal silver-based sensor. Experimental results show that the maximum sensitivity of the MoS2-modulated sensor in the detection range of RI from 1.415 to 1.420 is 16000 nm/RIU. The RI sensitivity of the MoS2-modulated sensor is increased by 167.35% compared with that of silver-based sensors, which means that the sensor is suitable for high-sensitivity detection applications of specific substances.

Twist detection is of great significance in industrial production, aerospace, biomedicine, and other fields. Aiming at the problem of the low sensitivity of the twisted sensor, this article proposed and prepared a kind of fiber twist sensor with high sensitivity based on Sagnac interference. The sensitive area of the sensor is a helical elliptical-core polarization maintaining (HEPM) fiber, the optical fiber with an elliptical core has linear birefringence property, and when the fiber is rotated, it has circular birefringence property. The HEPM fiber is plugged into the light loop to form Sagnac interference. Since circular birefringence is proportional to the degree of fiber distortion, the interference spectral trough will respond to different angles of fiber torsion. In addition, the sensor can not only identify the twist direction but also maintain good stability in different twist directions. The experimental results show that the free spectral range (FSR) of the interference spectrum increases and the sensitivity of twist sensing increases as the length of the used HEPM fiber decreases. The maximum twist sensitivity that can be achieved is 8740.64 pm/(rad/m) when the length of HEPM fiber is 15 cm in the twist range of plus or negative 120°, which is higher than the sensitivity of existing studies. The proposed sensor can be used for high-sensitivity distortion sensing. The temperature stability of the sensor is studied experimentally, and a sensing matrix is established that can simultaneously measure the torsion and temperature to eliminate the error caused by temperature. In summary, the proposed sensor not only has high sensitivity but also has an excellent linear response and can identify the twist direction, which has great potential in practical distortion detection.

Sensitivity is an important index parameter for evaluating the performance of a sensor. To improve the sensitivity of the sensor, we propose and demonstrate a surface plasmon resonance (SPR) fiber sensor based on Ti3C2Tx-Mxene/silver film. A V-shaped photonic crystal fiber (V-PCF) is used as the sensing probe, and a silver film is deposited on its surface by magnetron sputtering to excite the SPR effect. Multimode fibers are used to transmit signals at both ends of the sensor probe. Simulation results show that light can be stably transmitted in the cladding of the V-PCF. Experimental results show that the refractive index (RI) measurement range of the sensor is between 1.333 and 1.420, and the maximum RI sensitivity is 20188 nm/RIU; In order to extend the detection function of the sensor, we coated PDMS film on the Ti3C2Tx-MXene/silver film. When the sensor is used to measure temperature, the maximum temperature sensitivity is 9.33 nm/°C in the range of 0 °C–100 °C. Therefore, the proposed composite film structure sensor in this paper has the advantages of ultra-high detection sensitivity and oxidation resistance, which can have a great competitive advantage in the sensing field.

In order to cope with the crosstalk between temperature and refractive index (RI) caused by high-temperature environments, this study proposes to modify the surface plasmon resonance (SPR) fiber optic sensors with molybdenum disulfide (MoS2). MoS2 efficiently modulates the resonance wavelength, enabling the sensor to operate in high-temperature environments. The effect of MoS2 film thickness on the resonance wavelength was investigated by depositing MoS2 film on the surface of no-core fiber (NCF) using the magnetron sputtering method. The analysis shows that MoS2 can induce a significant redshift of the resonance dip, and the degree of redshift is related to the film thickness. In addition, a dual-parameter SPR sensor capable of detecting RI at high temperatures was prepared in this work by selecting the optimal Ag film thickness and MoS2 film thickness. The sensor was obtained by cascading an Ag-based NCF with an Ag/MoS2-based NCF, which was simulated and tested experimentally. The results show that the maximum temperature sensitivity is 4.3 nm/°C over the 50 °C–90 °C temperature range. The maximum RI sensitivity is 5243.4 nm/RIU over the RI range of 1.333–1.395. The test results also show that the two channels of the sensor are independent of each other and have good stability. Therefore, Ag/MoS2-based SPR sensors have the advantages of adjustable bandwidth, dual-parameter independent detection, and high sensitivity. These are essential in the future fields of multiparameter sensing, compensated detection, and real-time biomonitoring.