A UV-Vis spectroscopic detection method for cobalt ions in zinc sulfate solution based on discrete wavelet transform and extreme gradient boosting.

Zinc is a crucial strategic metal resource. The concentration of cobalt ions in zinc refining solution significantly impacts the efficiency of zinc electrolysis production. The traditional method of detecting cobalt ions in zinc solution is time-consuming, labor-intensive and ineffective. However, optical detection offers the advantage of high efficiency and low cost, making it a potential replacement for the traditional method. In this study, the spectral curve of cobalt ions in zinc solution is detected by ultraviolet-visible (UV-Vis) spectrophotometry. Additionally, we propose a model for the concentration-absorbance relationship of cobalt ions in zinc solution based on discrete wavelet transform and extreme gradient boosting (DWT-XGBoost) algorithms. First, the spectral curve's information region is denoised by using Savitzky-Golay (S-G) smoothing. Then, the denoised spectra is utilized to extract features through discrete wavelet transform and principal component analysis. These features are used as inputs to the XGBoost model to establish prediction models for low and high cobalt ions in zinc solution. Bayesian optimization is implemented to adjust the model's hyperparameters, including learning rate, feature sampling ratio, to enhance the prediction performance. Finally, applying the model to zinc solution samples from a zinc smelter and compared with other state-of-the-art algorithms, the DWT-XGBoost algorithm exhibits the lowest RMSE, MAE and MAPE, with values of 0.034 mg/L, 0.025 mg/L, 6.983 % for low cobalt and with values of 0.231 mg/L, 0.067 mg/L and 0.472 % for high cobalt. The experimental results demonstrate that the DWT-XGBoost model exhibits significantly superior prediction performance.

High-resolution liquid level sensor utilizing a microwave photonics interrogated multicore fiber interferometer.

We propose and experimentally demonstrate a high-resolution, high-sensitivity liquid level sensor based on a multicore fiber (MCF) Michelson interferometer (MI), where the sensing fiber is securely affixed to a cantilever beam, such that liquid level variations will change the beam's curvature, meanwhile leading to a substantial phase difference between the two interfering arms of the MI, and the sensor is interrogated using a microwave photonics filter (MPF) system, which can provide greatly enhanced measurement resolution compared to the traditional optical wavelength demodulation methods. The angular position of the MCF is precisely calibrated to ensure optimal sensitivity of the MI sensor. As a result, within a measurement range of up to ±14 cm, the proposed liquid level sensor achieves a sensitivity of 10.35 MHz/cm and an impressive resolution of 0.04835 cm. The proposed sensor has unique advantages of high sensitivity, superior resolution, long-term stability, etc.

Hypermethylation of the Bmp4 promoter dampens binding of HIF-1α and impairs its cardiac protective effects from oxidative stress in prenatally GC-exposed offspring.

The exposure to an unhealthy environment in utero can lead to the occurrence of cardiovascular diseases in the offspring. Glucocorticoids (GC) are essential for normal development and maturation of fetal organs and is a first-line treatment for pregnant women affected by autoimmune diseases. However, excess prenatal GC exposure might program the development of fetal organs and cause a number of chronic diseases in later life. Our previous studies indicated that cardiac functions were significantly compromised in rat offspring prenatally exposed to the synthetic glucocorticoid dexamethasone (DEX), only after ischemia-reperfusion. In the present study, we further observed that DNA hypermethylation of bone morphogenetic protein 4 (Bmp4) promoter in cardiomyocytes caused by prenatal DEX exposure substantially dampened the binding activity of transcription factor HIF-1α induced by cardiac ischemia. Therefore, prenatal DEX exposure inhibits the induction of BMP4 upon I/R and attenuates the protective effects of BMP4 in cardiomyocytes, which eventually manifests as malfunction of the adult heart. Moreover, we employed two cardiac-specific Bmp4 knock-in mouse models and found that in vivo BMP4 overexpression could rescue the cardiac dysfunction caused by prenatal GC exposure. In depth mechanistic research revealed that BMP4 protects the cardiomyocytes from mitophagy and apoptosis by attenuating mitochondrial PGC-1α expression in a p-Smad and Parkin-dependent manner. These findings suggest that prenatal GC exposure increases the susceptibility of the offspring's heart to a "second strike" after birth, due to the failure of hypoxia-induced HIF-1α transactivation of the hypermethylated Bmp4 promoter in cardiomyocytes. Pretreatment with the DNA methylation inhibitor, 5-Aza-2'-deoxycytidine, could be a potential therapeutic method for this programming effect of GC exposure during pregnancy on neonatal cardiac dysfunction.

Study of a Si-based light initiated multi-gate semiconductor switch for high temperatures.

Light initiated multi-gate semiconductor switch (LIMS) is a kind of power electronic device which has many differences from traditional thyristor triggered by electric pulse. LIMS is triggered by laser, the turn-on time is smaller, and the anti-electromagnetic interferences is strong. The opening mode of LIMS is obviously different to traditional thyristor. After the laser into the gate area, a large number of electrons and holes will appear in P-base region, holes gather in the area of P-base in PN junction J2, and electrons gather in N-drift region around the PN junction J2. PN junction J2 will open first, then PN junction J3 opens. The delay time of the NPN and PNP thyristors is close to zero when the laser pulse is narrow and the peak power is high, so the turn-on velocity is fast. To optimize the characteristics of the LIMS at high temperatures, we propose a new structure of the LIMS with the optimization of the n+ layer, circular light gate, and the new-style edge termination. The diameter of the LIMS is 23 mm. The experiment results show that the leakage current of the proposed LIMS has been decreased from more than 1 mA to 500 µA at 125 °C, the output current of the LIMS is 10.2 kA with a voltage of 4 kV at 85 °C, and the output current of the LIMS is 12.1 kA with a voltage of 4 kV at - 55 °C. Additionally, di/dt is larger than 30 kA/µs.

All-solid-state pulsed current injection source based on the light initiated multi-gate semiconductor switches.

To study the damage and protection mechanism of the transient electromagnetic pulse to the cables of the electronic equipment under test, an all-solid-state pulsed current injection source with light initiated multi-gate semiconductor switches is developed. The output peak current range of the prepared all-solid-state pulsed current injection source was 0.1-1 kA, the risetime was 18 ns, and the pulse width was 520 ns. In addition, the waveforms of the output peak current were consistent.

Decrease in SHP-1 enhances myometrium remodeling via FAK activation leading to labor.

Preterm birth is one of the most common complications during human pregnancy and is associated with a dramatic switch within the uterus from quiescence to contractility. However, the mechanisms underlying uterine remodeling are largely unknown. Protein kinases and phosphatases play critical roles in regulating the phosphorylation of proteins involved in the smooth muscle cell functions. In the present study, we found that Src-homology phosphatase type-1 (SHP-1, PTPN6) was significantly decreased in human myometrium in labor compared with that not in labor. Timed-pregnant mice injected intraperitoneally with the specific SHP-1 inhibitor protein tyrosine phosphatase inhibitor I (PTPI-1) manifested significantly preterm labor, with enriched plasmalemmal dense plaques between myometrial cells and increased phosphorylation at Tyr397 and Tyr576/577 sites of focal adhesion kinase (FAK) in myometrial cells, which remained to the time of labor, whereas the phosphorylation levels of ERK1/2 and phosphatidylinositol 3 kinase (PI3K) showed a rapid increase upon PTPI-1 injection but fell back to normal at the time of labor. The Tyr576/577 in FAK played an important role in the interaction between FAK and SHP-1. Knockdown of SHP-1 dramatically increased the spontaneous contraction of human uterine smooth muscle cells (HUSMCs), which was reversed by coinfection of a FAK-knockdown lentivirus. PGF2α downregulated SHP-1 via PLCß-PKC-NF-κB or PI3K-NF-κB pathways, suggesting the regenerative downregulation of SHP-1 enhances the uterine remodeling and plasticity by activating FAK and subsequent focal adhesion pathway, which eventually facilitates myometrium contraction and leads to labor. The study sheds new light on understanding of mechanisms that underlie the initiation of labor, and interventions for modulation of SHP-1 may provide a potential strategy for preventing preterm birth.

[The immune microenvironment in maternal-fetal interface contributes to the parturition and preterm labor].

The maintenance of human pregnancy and the initiation of parturition are closely related with the dynamic balance of the maternal-fetal immune microenvironment. Implantation of the blastocyst into the maternal decidua is the first step in pregnancy establishment, which is favored by the abundant blood flow and the immunotolerant microenvironment maintained by the balance of immune cells. The parturition resembles an inflammatory response that includes secretion of cytokines by resident and infiltrating immune cells into reproductive tissues and the maternal-fetal interface, which promotes the delivery of fetus from maternal organism. Therefore, the immune microenvironment in maternal-fetal interface regulates the critical steps of pregnancy and parturition. When the maternal-fetal immune microenvironment is imbalanced or impaired, miscarriage or preterm labor would happen. This article reviews the roles and mechanisms of several important immune cells in the maternal-fetal interface during the parturition and preterm labor.

Study on eccentricity effects of the rod-pinch diode radiography source.

The rod pinch diode (RPD) is a cylindrical pinched beam diode that generates intense pulsed bremsstrahlung X-ray radiation with a small diameter. In practice, the anode and cathode structures of the RPD may be eccentric due to the mechanical deformation and mounting errors. In theory, this eccentricity changes the physical characteristics of the RPD, which in turn affects the X-ray production. To study the performance variation induced by eccentric electrodes, the electrode concentricity evaluation system is used to quantify the concentricity of the anode and cathode. Then a series of experiments are carried out with different concentricity deviations, and the electrical performance, the radiation dose, and the X-ray pulse signal among different shots are analyzed. These results have shown that, within a certain eccentricity range, the overall performances of the RPD, including the diode impedance and the X-ray production, change very little. Going beyond this range, the average impedance decay rate increases significantly, resulting in accelerated impedance collapse and shortened voltage pulse width. Consequently, X-ray dose distribution and the X-ray pulse width are both reduced. These results are helpful in understanding the RPD characteristics from a different perspective as well as providing a method to determine the designing and mounting criteria of the electrodes of rod-pinch diode.

A novel compact low impedance Marx generator with quasi-rectangular pulse output.

In this paper, a novel low impedance compact Marx generator with near-square pulse output based on the Fourier theory is developed. Compared with the traditional Marx generator, capacitors with different capacity have been used. It can generate a high-voltage quasi-rectangular pulse with a width of 100 ns at low impedance load, and it also has high energy density and power density. The generator consists of 16 modules. Each module comprises an integrative single-ended plastic case capacitor with a nominal value of 54 nF, four ceramic capacitors with a nominal value of 1.5 nF, a gas switch, a charging inductor, a grounding inductor, and insulators which provide mechanical support for all elements. In the module, different discharge periods from different capacitors add to the main circuit to form a quasi-rectangular pulse. The design process of the generator is analyzed, and the test results are provided here. The generator achieved pulse output with a rise time of 32 ns, pulse width of 120 ns, flat-topped width (95%-95%) of 50 ns, voltage of 550 kV, and power of 20 GW.

Design of compact Marx module with square pulse output.

Compact pulsed power system based on compact Marx generator is widely used in terms of drive resistance and capacitive loads. This system usually adopts high performance components such as high energy density capacitors, compact switches, and integrated structure. Traditional compact Marx generator can only output double-exponential pulse profile. In this paper a compact, low-impedance Marx module which can output rectangular pulse profile is design and tested. This module has multiple circuits of different discharge frequencies in parallel to generate quasi-rectangular pulse. Discharge characteristic of an ideal module with infinite branches is calculated theoretically. A module with two branches has been designed and tested. Test results show that the impedance of the module is 1.2 Ω. When charging voltage is 100.6 kV and load resistance is 1 Ω, the peak output pulse is 45.2 kV voltage, the peak power is about 2 GW, the pulse width is about 130 ns, and the rise time is about 35 ns. The energy density and power density of the module are 15 kJ/m(3) and 140 GW/m(3), respectively.

Method for calibrating a Rogowski coil of fast time response.

A new method was designed for calibrating a Rogowski coil of fast time response. The method is based on the cable pulser method except that the voltage signal pick-off output was moved to a position with a distance l from the load. If 2l/v is longer than the time duration of the forward voltage pulse u(f)(t), the reflected voltage pulse u(r)(t) could be separated from u(f)(t) and directly measured. Using the formula i(t)=[u(f)(t)-u(r)(t)]/50 to calculate the primary current of the Rogowski coil, the coil could be more accurately calibrated.