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In this study, all‐optical organic–inorganic hybrid waveguide switches are proposed based on the photothermal effect of Au‐MOF composites. The embedded waveguide structure is directly defined using SiO2 grooves on a silicon substrate. Self‐synthesized Au‐MOF/PMMA and SiO2‐TiO2 network grafting PMMA are used as the core and cladding materials, respectively. The organic–inorganic hybrid shielding layer is formed using an oxygen ion etching process to avoid corrosion from the cladding solvent. A directional coupling switching structure is designed and fabricated. The switching time of the all‐optical device is 500 µs, the photothermal tuning sensitivity is 19.10 nm mW−1, the driving optical power consumption is 0.67 mW, and the extinction ratio is close to 9.83 dB. This technique is desirable for photothermal control of light in an all‐optical signal‐processing network. [ABSTRACT FROM AUTHOR]

(1) Background--The rapid development of forest ecotourism has also brought environmental pollution and ecological damage. In order to better respond to the "Two Mountains" theory and implement the ecological civilization construction strategy, and promote the sustainable development of forest ecotourism industry, it is crucial to clarify and guide tourists' green purchasing behavior. Studying the formation mechanism of tourists' green purchase intention is helpful to the sustainable development of forest ecotourism. (2) Methods--The research hypotheses were proposed based on the theory of planned behavior (TPB), value-belief-norm theory (VBN) and their integrated framework. The research data came from the questionnaire survey of the tourists in Wuyishan National Park in Fujian Province in October 2023, and a total of 407 valid questionnaires were obtained. Then, a structural equation model was constructed to analyze the formation mechanism of tourists' green purchase intention. (3) Results--First, the theoretical model of the formation mechanism of green purchase intention constructed in this paper has strong explanatory power and predictive power for tourists' green purchase intention. The integration framework of TPB and VBN is effective in explaining and predicting the influencing factors and formation mechanism of tourists' green purchase intention. Second, in the hypothetical path designed according to TPB, the research results show that the green purchasing behavior attitude and subjective norms have a positive impact on tourists' green purchase intention, while the perceived behavior control has no significant impact on tourists' green purchase intention. In the hypothetical path designed according to the VBN theory, the research results show that altruism values have a significant positive impact on the awareness of consequence, the awareness of consequence has a significant positive impact on the attribution of responsibility, the attribution of responsibility has a significant positive impact on the moral norms, and the moral norms has a positive impact on the tourists' green purchase intention. This indicates that the formation of tourists' green purchase intention is influenced by the chain causal mechanism of the VBN theory. In the hypothetical path designed according to the TPB-VBN integrated framework, the research results show that the awareness of consequence has a positive impact on the perceived behavior control and green purchasing behavior attitude, and the subjective norms have a positive impact on the moral norms, which indicates that the interaction of TPB and VBN theory can further explain the formation mechanism of tourists' green purchase intention. Third, there is no significant difference in the green purchase intention of the tourists of different genders and ages, but there is a significant difference between the tourists with different education levels, and with the increase of education level, the green purchase in tention of the tourists increases significantly. (4) Conclusions and Discussions--In order to improve tourists' green purchase intention, the following policy suggestions are put forward: First, strengthen publicity and education, enrich publicity content and broaden publicity channels, so as to enhance tourists' ecological awareness and moral responsibility in purchasing green tourism products and services, and enhance their altruistic values. Second, improve the tourism market, explore the green, low-carbon and high-quality development of forest ecotourism, and enhance the green purchasing power of tourists. Enrich the product and service categories and improve the availability of green tourism products and services. Enterprises are encouraged to design and produce green tourism products to convey the concept of sustainable development of forest ecotourism. Third, create a good social atmosphere to form a collective and social green purchasing power, and enhance the sense of responsibility and model of tourists. Use a variety of means comprehensively to strengthen the social norms on the tourists' individual behavior constraints and guidance. Shape the collective and social forces of green purchasing behavior through publicity and education, institutional norms and public welfare activities. [ABSTRACT FROM AUTHOR]

An efficient and stable fiber coating is of great importance for solid-phase microextraction (SPME). In this study, carboxylated mesoporous carbon hollow spheres (MCHS-COOH) were developed as an efficient SPME coating of polar aromatic amines (AAs) for the first time. The MCHS-COOH coating material with high specific surface area (1182.32 m2 g−1), large pore size (10.14 nm), and rich oxygen-containing groups was fabricated via a facile H2O2 post-treatment. The as-prepared MCHS-COOH-coated fiber exhibited fast adsorption rate and excellent extraction properties, mainly due to its π–π interactions, hollow structure, and abundant affinity sites (carboxyl groups). Subsequently, coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS), a sensitive method with low limits of detection (0.08–2.0 ng L−1), a wide linear range (0.3–500.0 ng L−1), and good repeatability (2.0–8.8%, n = 6) was developed for the analysis of AAs. The developed method was validated against three river water samples, with satisfactory relative recoveries being obtained. The above results demonstrated that the prepared MCHS-COOH-coated fiber exhibited good adsorption capacity, suggesting a promising application to monitor trace polar compounds in real environment. [ABSTRACT FROM AUTHOR]

The objective of this paper was to investigate acoustic pressure waves and the transient flow structure emitted from the single bubble near an elastic boundary based on the particle image velocimetry (PIV). A combination of an electric-spark bubble generator and PIV were used to measure the temporal bubble shapes, transient flow structure, as well as the mid-span deflection of an elastic boundary. Results are presented for three different initial positions near an elastic boundary, which were compared with results obtained using a rigid boundary. A formula relating velocity and pressure was proposed to calculate the acoustic pressure contours surrounding a bubble based on the velocity field of the transient flow structure obtained using PIV. The results show the bubbles near the elastic boundary presented a "mushroom" bubble and an inverted cone bubble. Based on the PIV-measured acoustic pressure contours, a significant pressure difference is found between the elastic boundary and the underside of the bubble, which contributed to the formation of the "mushroom" bubble and inverted cone bubble. Furthermore, the bubbles had opposite migration direction near rigid and elastic boundaries, respectively. In detail, the bubble was repelled away from the elastic boundary and the bubble was attracted by the rigid boundary. The resultant force made up of a Bjerknes force and buoyancy force dominated the migration direction of the bubble. [ABSTRACT FROM AUTHOR]

We present the design and performances of a broadband 1 × 2 mode-independent thermo-optic (TO) switch based on Mach-Zehnder interferometer (MZI) with multimode interferometer (MMI). The MZI adopts a Y-branch structure as the 3-dB power splitter and a MMI as the coupler, which are designed to be insensitive to the guided modes. By optimizing the structural parameters of the waveguides, mode-independent transmission and switching functions for E 11 and E 12 modes can be implemented in the C + L band, and the mode content of the outputs is the same as the mode content of the inputs. We proved the working principle of our design based on polymer platform, which was fabricated by using ultraviolet lithography and wet-etching methods. The transmission characteristics for E 11 and E 12 modes were also analyzed. With the driving power of 5.9 mW, the measured extinction ratios of the switch for E 11 and E 12 modes are larger than 13.3 dB and 13.1 dB, respectively, over a wavelength range of 1530 nm to 1610 nm. The insertion losses of the device are 11.7 dB and 14.2 dB for E 11 and E 12 modes, respectively, at 1550 nm wavelength. The switching times of the device are less than 840 µs. The presented mode-independent switch can be applied in reconfigurable mode-division multiplexing systems.

Pyrethroids (PYs) have been widely used to control pests and prevent diseases in tea gardens. However, with the increasingly stringent pesticide testing standards in the import and export trade of tea, there is an urgent need for methods to detect trace amounts of PYs in tea. In this study, a covalent organic framework (COF) material TpBD with excellent thermal/chemical stability, high porosity, and a large specific surface area was prepared by a room-temperature solution-suspension approach (SSA). TpBD-coated solid phase microextraction (SPME) fibers were fabricated by coating the material on etched stainless-steel fibers by a simple physical coating method. The fibers were used in combination with gas chromatography-tandem mass spectrometry (GC-MS/MS) to establish a highly sensitive method for the detection of PYs. The enrichment factors of this method for cyfluthrin, cypermethrin, flucythrinate, fenvalerate, and deltamethrin were 702-2687. The method showed low LODs (0.1-0.5 ng/L), wide linear ranges (0.2-800 ng/L), good linearities (correlation coefficients ( R )≥0.9991) and acceptable repeatabilities (RSD≤11.0%, n =3). Green tea and oolong tea samples were analyzed using the developed method, and trace levels of the five PYs were successfully detected. The recoveries of the spiked PYs in the real green tea and oolong tea samples were in the range of 80.2%-109.5%. Experimental results showed that the established analytical method is suitable for the determination of PY pesticides in tea. Furthermore, the TpBD material was successfully prepared by the SSA method, demonstrating that the method has good universality and excellent potential for the simple synthesis of other COF materials.

Gambogic acid (GA), a promising anticancer candidate, is a polyprenylated xanthone abundant in the resin of Garcinia morella and Garcinia hanburyi. Electron capture-atmospheric pressure chemical ionization (EC- APCI) and electrospray ionization (ESI) techniques, both in the negative ion mode, were evaluated regarding ionization, fragmentation patterns and sensitivity for simultaneous liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of GA and its main circulating metabolite, 10-hydroxygambogic acid (10-OHGA) in dog plasma. Both analytes underwent extensive in-source fragmentation in EC-APCI, which was not desirable for reliable quantification of these analytes, whereas the substitution of ESI for EC-APCI almost eliminated the source instability of both analytes. Negative ion ESI was, therefore, chosen for the development of an LC-MS/MS method for simultaneous determination of these analytes. After protein precipitation by acetonitrile, all analytes were separated on a Luna C18 HST column (50 x 2.0 mm i.d., 2.5 microm) with a mobile phase of 20 mmol L(-1) ammonium acetate water solution containing 0.2% acetic acid:acetonitrile (18:82, v/v). The detection was performed on a tandem mass spectrometer using selective reaction monitoring mode. Calibration curves were linear over the range of 10-6000 ng mL(-1) for GA and 3-2000 ng mL(-1) for 10-OHGA. The method was successfully applied to the pharmacokinetics study of GA injection in six beagle dogs.