Yong Wei

Conventional two-dimensional fiber optic interferometric curvature sensor often suffers from significant sensitivity disparities between orthogonal directions. To address this limitation, this article proposes a two-dimensional fiber interferometric curvature sensor based on an eccentric fiber combined with offset fusion splicing. The eccentric fiber is employed as the sensing fiber, and transverse offset fusion splicing is performed orthogonally to its biased core. This configuration induces asymmetric optical fields distribution of the core and cladding modes in the two orthogonal directions, resulting in substantial field offset that enables high-sensitivity two-dimensional curvature sensing. The experimental results indicate that within the curvature range of 0-0.32 m^-1, the sensor achieves a maximum sensitivity of 48.54 nm/m^-1 in the ± X and ± Y directions and a minimum sensitivity of -41.02 nm/m^-1. The proposed method offers a facile fabrication route and delivers high sensitivity for two-dimensional curvature measurement.

Fiber Mach Zehnder interferometer (MZI) strain sensor can be used in aerospace, semiconductor, medical and other fields. In situations where the strain is small, the sensitivity of MZI needs to be further improved. However, due to the limitation of the fiber optic elastic coefficient, the effectiveness of existing sensitization methods is limited. This article proposes a high-sensitivity arc shaped MZI strain sensor based on wave vector axial tilt angle modulation (Arc shaped MZI). Which is formed by cascading arc-shaped fiber optic and multimode fiber optic to form a fiber MZI. During the strain process, the arc shaped MZI undergoes deformation, and the wave vector axial tilt angle of the cladding mode changes. However, the change in wave vector axial tilt angle of the cladding mode is no longer limited by the fiber optic elastic coefficient, and the propagation constant of the cladding mode changes significantly during the strain process, achieving a high-sensitivity MZI strain sensor. The experimental results indicate that the strain sensitivity of Arc shaped MZI is as high as 357.23 pm/μϵ, which can be used for high-precision real-time strain detection in precision instruments with small strain changes in the future.

Strong refractive index (RI) modulation type long-period fiber grating (LPFG) has the advantages of requiring fewer modulation period and shorter sensing area length. However, during the production process, multiple types of optical fibers need to be precisely cut to a fixed length and spliced together, which leads to problems such as low fabrication repeatability and poor mechanical strength. This article proposes a strong RI modulation LPFG (SCS-LPFG) that uses only single-mode fiber and periodically constructs an S-shaped fiber core. Owing to the high degree of curvature of the S-shaped fiber core, fiber core light will directly enter the cladding in the middle of the S-shaped core for transmission, thereby achieving strong refractive index modulation. Results of the experiments demonstrate that the sensing area length of SCS-LPFG is only 2.12mm, and its sensing performance is excellent. The strain, curvature, and temperature sensitivities are 25.8pm/με, 15.6nm/m^-1, and 89.7pm/°C, respectively. SCS-LPFG offers a novel approach for the fabrication of strong RI modulated LPFG, which can be integrated into precision instruments and structures with small object volumes for the detection of various physical quantities.

Background: Non-small cell lung cancer (NSCLC) is a common malignancy with limited efficacy of established therapies and a poor prognosis that often entails a high financial burden. Eupatorium lindleyanum DC. and its main component Eupalinolide A (EA) are clinically used for the management of chronic tracheitis. Therefore, the aim of this study was to investigate the effects of EA on NSCLC and its underlying molecular mechanisms. Methods: The effect of EA was assessed on A549 and H1299 tumour cells by flow cytometry, qRT-PCR, western blotting, TUNEL assay, molecular docking, RNA sequencing, non-target metabolomics experimental methodology, and phosphoproteomics to explore the molecular pathways and specific targets. A mouse tumour xenograft model was used to evaluate its effect in vivo . Results: EA inhibited cell proliferation by arresting the cell cycle at the G2/M phase (increasing the proportion of G2-phase cells in A549 cells from 2.91% to 21.99% and their proportion in H1299 cells from 8.22% to 18.91%). It also promoted apoptosis (increasing the total apoptotic rate in A549 cells from 1.79% to 47.29% and that in H1299 cells from 4.66% to 44.43%) as well as ferroptosis (increasing ROS production by 2.46-fold in A549 cells and by 1.32-fold in H1299 cells). This mechanism was mediated by the modulation of the synthesis of unsaturated fatty acids through the downregulation of stearoyl-CoA desaturase 1 (SCD1) expression, which was reduced by 34% in A549 cells and by 48% in H1299 cells. Notably, the supplementation of oleic acid counteracted the inhibitory effect of EA on cell proliferation and migration. These effects of EA were due to the involvement of the AMPK- mTOR signalling pathway. EA treatment (25 mg/kg) markedly inhibited tumour growth in vivo in a xenograft model; both tumour weight and tumour volume decreased by more than 60% without significantly affecting the body weight of tumour-bearing mice. Conclusion: EA inhibited the proliferation and migration of NSCLC cells by the modulation of lipid metabolism through the activation of the ROS-AMPK-mTOR-SCD1 signalling pathway. Therefore, EA might be considered as a promising candidate in the development of therapeutics against NSCLC.

Fiber optic Mach–Zehnder interferometer (MZI) strain sensors are widely used in many fields, but their sensitivity needs further improvement. This article proposes a new method of strain sensitization by simultaneously increasing the effective refractive index difference and the difference in sensing path length between the fiber core and cladding to increase the change in optical path difference. By replacing the single-mode fiber in the middle part of the multimode-single mode-multimode (MSM) structure with spiral core fiber fabricated by the eccentric fiber, the separation of the core sensing length and the cladding sensing length of the sensing fiber was achieved, and the length difference of the fiber core and cladding sensing path was increased. However, due to twisting processing of the eccentric fiber, the higher order cladding modes were excited, thereby increasing the effective refractive index difference of the fiber core and cladding. By experimental testing, the highest strain sensing sensitivity of −72.9 pm/ $\mu \varepsilon $ was achieved, providing a new idea for the further development of fiber optic integrated MZI strain sensing.

Hexavalent chromium (Cr(VI)), as a highly toxic and carcinogenic heavy metal ion, poses a serious threat to the environment and human health. Therefore, specific detection of it is of great significance. Based on this, this article proposes a balloon shaped fiber SPR sensor with microsphere structure for specific detection of hexavalent chromium ions. The balloon structure facilitates the formation of insertable sensing probe, and the microsphere structure located on one side of the balloon structure can adjust the incidence angle of light in the sensing area to enhance the sensitivity of the sensor, resulting in a maximum refractive index sensitivity of 5068 nm/RIU. Modifying 4-mercaptoethylpyridine on the surface of the gold film of the sensor can achieve specific recognition of Cr(VI). The experimental results indicate that the balloon shaped SPR sensor with microspheres proposed in this paper has a detection limit of as low as 0.57ng/mL for Cr (VI) in the detection range of 1ng/mL-100μg/mL, with a detection time of 3 minutes, providing a new method for rapid, low concentration, and specific detection of Cr(VI).

The existing directional recognition fiber optic interferometric curvature sensor is usually based on special optical fiber or complex microfabrication, which has problems such as high cost and fragile structure. This article proposes an asymmetrically coated direction recognition fiber optic interferometric curvature sensor. An MSM type fiber optic interferometer is fabricated, the high refractive index UV adhesive is coated on the lower half of the sensing single-mode fiber segment by a U-shaped soft groove. Then concave and convex bending are applied to the sensor separately, the energy of the core mode field is distributed along the central axis of the fiber, and the energy of the cladding mode field is always distributed in UV coating zone, which is located in the stretching and compression areas of the sensor. The interference valleys are blue shifted and red shifted respectively, achieving bending direction recognition and curvature sensing. The experimental results indicate that the sensor has a sensitivity of -20.92nm/m^-1 for concave bending and 20.70mm/m^-1 for convex bending within the curvature detection range of 0-1m^-1. This article provides a new idea for the structural design and manufacturing method of directional recognition fiber optic interferometric curvature sensor. The sensor has high mechanicashl strength, simple manufacturing, low cost, and good application prospect.