Doxycycline (DC) is an antibiotic that exists in the environment and urgently needs to be effectively removed. Herein, the light/BiVO
4
@Ag
2
O/H
2
O
2
system and light/BiVO
4
@Ag
2
O system were ...constructed to achieve effective degradation of DC. Under the same degradation conditions, the efficiency and mechanism of two systems on DC degradation were compared. The results showed that the removal rate of DC in light/BiVO
4
@Ag
2
O/H
2
O
2
system was better than that in light/BiVO
4
@Ag
2
O system. The optimal pH ranges were 3.5–9.5 and 7.5–9.5 for light/BiVO
4
@Ag
2
O/H
2
O
2
and light/BiVO
4
@Ag
2
O systems, respectively. The optimal water temperatures were both 35 °C in two systems. The optimal BiVO
4
@Ag
2
O dosages were both 182 mg/L. The Cl
−
,
SO
4
2
-
and
BrO
3
-
had promoting effects on DC removal, while
NO
3
-
and
PO
4
3
-
had inhibitory effects on DC removal. The capture experiment showed that h
+
, ·O
2
−
and ·OH existed in two degradation systems, among which h
+
played an important role. Analysis of degradation intermediates showed that the proportion of smaller molecules in light/BiVO
4
@Ag
2
O/H
2
O
2
visible light system was higher than that in light/BiVO
4
@Ag
2
O visible light system, indicating that oxidation active substances were more easily produced in light/BiVO
4
@Ag
2
O/H
2
O
2
system.
Indium tin oxide (ITO) thin-film thermocouples monitor the temperature of hot section components in gas turbines. As an in situ measuring technology, the main challenge of a thin-film thermocouple is ...its installation on complex geometric surfaces. In this study, an ITO thin-film thermocouple probe based on a sapphire microrod was used to access narrow areas. The performance of the probe, i.e., the thermoelectricity and stability, was analyzed. This novel sensor resolves the installation difficulties of thin-film devices.
The present study introduces a weak magnetic field sensor that utilizes a laminated cantilever structure, consisting of a magnetostrictive layer, a piezoelectric layer, and a substrate layer. ...Consequently, the transformation from the magnetic signal to the electrical signal is accomplished through the consistent mechanical stress in both layers. A comprehensive theoretical model has been developed to evaluate the impact of key structural parameters on the magnetoelectric (ME) sensing performance, enabling the optimization of the device design. By incorporating vanadium (V) as a dopant element, a Zn-V-O film with a piezoelectric coefficient as high as 35 pm/V is fulfilled. Furthermore, the high piezomagnetic properties of Galfenol make it a suitable candidate as a magnetostrictive layer. Sensor prototypes were fabricated for experimental verification through the utilization of MEMS technology. The film was characterized using techniques, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and piezoelectric force microscopy (PFM). The ME testing experiments indicated that the magnetostrictive coefficient could achieve about 9.32 kV/(cm <inline-formula> <tex-math notation="LaTeX">\cdot </tex-math></inline-formula> Oe) at resonant frequencies for sensors with varying lengths and a 20-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>-thick Si substrate. The proposed sensor exhibits promising potential for improving weak magnetic field detection performance.
Wall shear stress and flow direction provide a basis for analyzing the boundary layer conditions, investigating drag reduction mechanisms, and enhancing environmental perception. This work presents ...novel single-loop and dual-loop hot-film sensors driven by the constant temperature (CT), which are capable of simultaneously measuring wall shear stress and flow direction. Based on the heat transfer and fluid dynamics theory, a mathematical model is developed to analyze the flow directions. The sensors feature multilayer structures, where the numerous leads are concealed and embedded in the insulation layer to enhance their robustness and integration. Utilizing the microelectromechanical system technology, sensor prototypes with single-loop and double-loop are fabricated. In particular, a new process method for accomplishing junction holes in the polyimide (PI) insulation layer is proposed. The sidewall-to-bottom angle of junction holes fabricated through wet etching is ~29.4°. After metal lays are deposited in the junction holes, the upper and bottom surfaces of the insulation layer are able to conduct electricity. Moreover, a testing system consisting of a microchannel and a turbulence generator is established to carry out the experimental verification. Then, the hot-film sensors are tested in the microchannel with a maximum Reynolds number of Red = 8600. Low-frequency turbulence as well as natural transition signals are detected by the hot-film sensors successfully. In the range of wall shear stress from 0 to 14.2 Pa, the accuracies of the dual-loop and single-loop hot-film sensors in perceiving flow directions are better than ±3° and ±6.5°, respectively. This work assists to analyze the boundary layer states, to investigate drag reduction mechanisms, and to enhance environmental perception in flow field.
To solve the current problems with thin-film thermocouple signals on turbine blades in ultra-high temperature environments, this study explores the use of a through-hole lead connection technology ...for high-temperature resistant nickel alloys. The technique includes through-hole processing, insulation layer preparation, and filling and fixing of a high-temperature resistant conductive paste. The through-hole lead connection preparation process was optimized by investigating the influence of the inner diameter of the through-hole, solder volume, and temperature treatment on the contact strength and surface roughness of the thin-film for contact resistance. Finally, the technology was combined with a thin-film thermocouple to perform multiple thermal cycling experiments on the surface of the turbine blade at a temperature of 1000 °C. The results show that the through-hole lead connection technology can achieve a stable output of the thin-film thermocouple signal on the turbine blade.
A flexible hot-film sensor array for wall shear stress, flow separation, and transition measurement has been fabricated and implemented in experiments. Parylene C waterproof layer is vapor phase ...deposited to encapsulate the sensor. Experimental studies of shear stress and flow transition on a flat plate have been undertaken in a water tunnel with the sensor array. Compared with the shear stress derived from velocity profile and empirical formulas, the measuring errors of the hot-film sensors are less than 5%. In addition, boundary layer transition of the flat plate has also been detected successfully. Ensemble-averaged mean, normalized root mean square, and power spectra of the sensor output voltage indicate that the Reynolds number when transition begins at where the sensor array located is 1.82 × 10⁵, 50% intermittency transition is 2.52 × 10⁵, and transition finishes is 3.96 × 10⁵. These results have a good agreement with the transition Reynolds numbers, as measured by the Laser Doppler Velocimetry (LDV) system.
A novel resonant pressure sensor with an improved micromechanical double-ended tuning fork resonator packaged in dry air at atmospheric pressure is presented. The resonator is electrostatically ...driven and capacitively detected, and the sensor is designed to realize a low cost resonant pressure sensor with medium accuracy. Various damping mechanisms in a resonator that is vibrating at atmospheric pressure are analyzed in detail, and a formula is developed to predict the overall quality factor. A trade-off has been reached between the quality factor, stress sensitivity and drive capability of the resonator. Furthermore, differential sense elements and the method of electromechanical amplitude modulation are used for capacitive detection to obtain a large signal-to-noise ratio. The prototype sensor chip is successfully fabricated using a micromachining process based on a commercially available silicon-on-insulator wafer and is hermetically encapsulated in a custom 16-pin Kovar package. Preliminary measurements show that the fundamental frequency of the resonant pressure sensor is approximately 34.55 kHz with a pressure sensitivity of 20.77 Hz/kPa. Over the full scale pressure range of 100–400 kPa and the whole temperature range of −20–60 °C, high quality factors from 1,146 to 1,772 are obtained. The characterization of the prototype sensor reveals the feasibility of a resonant pressure sensor packaged at atmospheric pressure.
A new variant of MEMS surface fence is proposed for shear-stress estimation under high-speed, high-temperature flow conditions. Investigation of high-temperature resistance including heat-resistant ...mechanism and process, in conjunction with high-temperature packaging design, enable the sensor to be used in environment up to 400 °C. The packaged sensor is calibrated over a range of ~65 Pa and then used to examine the development of the transient flow of the scramjet ignition process (Mach 2 airflow, stagnation pressure, and a temperature of 0.8 MPa and 950 K, respectively). The results show that the sensor is able to detect the transient flow conditions of the scramjet ignition process including shock impact, flow correction, steady state, and hydrogen off.
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