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Cutterhead torque is a key operational parameter for earth pressure balance (EPB) TBM tunneling in soil strata. The effective management of cutterhead torque can significantly maintain face stability and ensure the tunneling machine operates steadily. The Shenzhen Metro Line 12 project at Shasan Station utilized the world's largest rectangular pipe jacking machine for constructing the subway station. This project has enabled the collection of relevant data to analyze the factors influencing cutterhead torque and to establish a predictive model. The data encompass an abundant array of cutterhead design parameters, operational parameters, properties of the excavated soil, and environmental factors, revealing the distribution characteristics of cutterhead torque during tunneling. The correlation between various factors and cutterhead torque has been examined. By employing multiple regression analysis and a Levenberg–Marquardt (L-M) algorithm-based neural network, an optimal prediction model for EPB cutterhead torque has been developed. This prediction model incorporates various factors, including cutterhead diameter, RPM, soil chamber pressure, soil shear strength, and the soil consistency index. And the degree of influence of each factor on the cutter torque was also revealed. The prediction results demonstrated good accuracy compared to previous models, providing valuable insights and guidance for EPB TBMs or pipe jacking machines operating in soil strata. The current limitations of this model and suggestions for future work have also been addressed. [ABSTRACT FROM AUTHOR]

Short circuit failure mode (SCFM) of integrated gate commutated thyristor (IGCT) under extreme failure is of vital importance in high voltage direct current power transmission based on modular multilevel converter technology. Due to the sealing housing package of IGCT, the short circuit mechanism is hard to be clarified. Considering this limitation, the current density changes in IGCT with different failure modes are studied under different current levels in a built integrated test system with the placed magnetic sensor array and thermal couple array. Then, the short circuit mechanism of failed IGCT is proposed based on the experimental results. IGCT with turn-off failure performs self-triggering effect due to the focused short current and increased temperature in the initial destruction area, which is usually located in a single position of the outer cathode rings. While IGCT with surge current failure shares the short current among multiple initial destruction areas, which are usually distributed evenly in the wafer area. Scanning electron microscope picture and energy dispersive X-Ray spectroscopy (EDX) analysis show that the formed conducting alloy has spread into the molybdenum plate deeply and the phenomenon of atom diffusion (molybdenum, silicon and aluminum) near the interface is observed. Finally, long term short circuit tests of more than 12 h with both turn-off failure and surge current failure under 3000 A prove the stable SCFM of IGCT. [ABSTRACT FROM AUTHOR]

The 6-in gate commutated thyristor (GCT) is suitable for hybrid dc circuit breaker (HDCB) application with its large chip area and high maximum controllable current (MCC), compared with traditional 4-in GCTs. P+ base doping dispersion control is of vital importance in the 6-in GCT chip. Based on the strong correlation between P+ base doping and the gate-cathode breakdown voltage (${V}_{\text {gbr}}$), P+ base doping dispersion is characterized through ${V}_{\text {gbr}}$. Test results show that ${V}_{\text {gbr}}$ dispersion in the 6-in GCT sample with etched depth of around $10~\mu \text{m}$ is about 2 V with the average ${V}_{\text {gbr}}$ of around 22 V. While ${V}_{\text {gbr}}$ dispersion in the sample with etched depth of above 20 $\mu \text{m}$ is above 6 V with the average ${V}_{\text {gbr}}$ of around 27 V. These are consistent with the 2-D simulation results. Then, P+ base doping parameter design is optimized through experiment. Both turn-on and turn-off characteristics of 6-in GCT samples with different P+ base doping parameter designs are compared with HDCB application. The final optimized 6-in GCT chip has no difficulty in turning on under a low dc-link voltage below 100 V and it can turn off 13 kA with the overvoltage of about 4.5 kV successfully, which shows potential in HDCB application. [ABSTRACT FROM AUTHOR]

Gate electrode inductance is a key factor for the controllable current capacity of unity-gain turn-off devices. However, the precise and credible measurement of this nH-level inductance is very difficult due to the compact structure of housing package. In this article, a precise measurement methodology of nH-level gate electrode inductance based on calculation-error-free algorithm for unity-gain turn-off devices is proposed. First, the turn-off process was modeled and discussed. Based on the feature of different stages, a customized extraction method is proposed for nH-level inductance measurement with ultrahigh accuracy. Then, a gate current measurement method for separate cathode rings with minimum inductance introduction was invented and discussed. After careful measurement and calculation, the gate electrode inductance for each region was derived and the abrupt change in gate contact region was observed and analyzed. The inductances measured in this article can be further utilized for housing structure optimization and lateral arrangement of segments on unity-gain turn-off chips. [ABSTRACT FROM AUTHOR]

The integrity of housing and feature of short circuit is hardly guaranteed for traditional power devices under overvoltage breakdown with following high surge energy. Thus, extra bypass thyristor is needed to achieve stable overvoltage bypass protection for submodules in modular multilevel converters at present. In this article, a novel controlled punch-through IGCT (CP-IGCT) is presented. Based on the punch-through breakdown principle instead of avalanche breakdown principle, the device can achieve breakdown at design voltage with uniformity, thermal stability, and robust package rupture-resilience. As a consequence, no extra sacrificial device is necessary. The fabricated sample proves a stable breakdown at 4000 V and a robust short-circuit feature after energy release of a 18 mF capacitor under 4500 V. [ABSTRACT FROM AUTHOR]

The performance of solid-state dc circuit breaker (SS-DCCB) is mainly determined by the on-state feature of power device. In this article, an optimized low on-state voltage integrated gate-commutated thyristor (LO-IGCT) for SS-DCCB is developed. First, the impacts of device parameters, including base length, carrier lifetime, and emitter injection efficiencies, on on-state voltage are presented. The boundary conditions raised by blocking voltage and safe operation area (SOA) are analyzed. Based on that, a three-step blocking-SOA-emitter optimization routine is proposed. Then, the optimization methodology for doping profiles in different regions, especially in n-drift, n buffer, p+ base, n+ emitter, and p+ emitter regions, is presented. The optimal values are derived with theoretical deduction or numerical calculation. After that, based the optimization result, samples of LO-IGCTs are fabricated and tested. The fabricated LO-IGCT sample shows a blocking voltage capability over 4500 V and an on-state voltage of 1.11 V at the current of 2000 A. The commercialized IGCT and IGBT optimized for high-frequency applications exhibits 1.23 and 1.85 times the on-state voltage under the same test configuration. [ABSTRACT FROM AUTHOR]

During pepper and tomato production seasons in 2013–2017, large-scale virus disease surveys were conducted in different regions of Yunnan Province, China. A total of 1,267 pepper and tomato samples with various virus-like symptoms were collected and analyzed for virus infections through dot enzyme-linked immunosorbent assay (dot-ELISA), polymerase chain reaction (PCR), and reverse-transcription (RT)-PCR. The detection results showed that 19 different viruses were present in about 50.9% of the assayed samples, and among these viruses, seven viruses were found in both pepper and tomato samples. Mixed infections with two to three of the 15 identified mixed infection types were found in the pepper samples and 10 identified mixed infection types were found in the tomato samples. Among the infected samples, Tomato spotted wilt orthotospovirus (TSWV) was the most common virus, with a detection rate of about 20.0% followed by Pepper vein yellows virus (PeVYV, 13.0%). This survey revealed for the first time that pepper is a natural host of Tobacco vein distorting virus (TVDV) worldwide and tomato is a natural host of Potato leafroll virus (PLRV) in China. PeVYV, Tobacco mild green mosaic virus (TMGMV) and Wild tomato mosaic virus (WTMV) were first time found in pepper and Tomato mottle mosaic virus (ToMMV) and Chilli veinal mottle virus (ChiVMV) were first time found in tomato in Yunnan Province. Finally, the virus incidences were higher in Kunming, Yuxi, Chuxiong, and Honghe region than other regions. [ABSTRACT FROM AUTHOR]

Compared with insulated-gate bipolar transistors, integrated-gate commutated thyristor (IGCT) has lower on-state voltage, higher reliability, and lower manufacturing costs, thus, making it more suitable for high-power applications. This article focuses on the full-time junction temperature extraction of IGCTs for high-power applications. An electrothermal model for IGCT is established. Nonlinear optimization and accuracy analysis of this model are performed, which proved that the model achieves good accuracy. On the basis of the electrothermal model, junction temperature during switching on, switching off, and off state is evaluated. The junction temperature during conduction is extracted based on the temperature-sensitive electrical parameter method. Combining these two schemes, a comprehensive method to extract full-time accurate junction temperature of IGCT for high-power application is proposed. An experimental platform of IGCT-based modular multilevel converters for high-power applications is built, and power cycling experiments at different voltage and current ratings of up to 2.2 kV/1.5 kA were carried out to verify the correctness and effectiveness of the proposed method. Results show the junction temperature profile over a long period. The junction temperatures of IGCT both in inverter and rectifier modes and under different power-loading conditions are compared with the proposed comprehensive method. [ABSTRACT FROM AUTHOR]

This article proposes that a modular multilevel converter (MMC) based on the integrated-gate commutated thyristor (IGCT) is a promising solution for future highvoltage dc (HVdc) applications. The system-level scheme and technical issues of the IGCT MMC are proposed, and the commutation behaviors of the IGCT and the snubber circuit in the MMC are analyzed. On this basis, the optimal designs of the anode inductor, power supply system, valve series, and submodule structure are proposed, and a comprehensive experimental platform is built. Detailed experiments are conducted, including a double-pulse switching experiment, a back-to-back power cycling experiment, and an MMC operation experiment. Furthermore, the correctness and effectiveness of the proposed IGCT MMC solution are verified. [ABSTRACT FROM AUTHOR]

DC circuit breakers (DCBs) are crucial components in dc power systems. The ultralow operating frequency of the DCBs enables the use of gate-commutated thyristors (GCTs) in the DCBs. This paper proposed a 6-in dual-gate ring commutated thyristor (DGRCT) for the DCB applications. The wafer and package designs of the DGRCT are first presented and discussed, analyzing the principles of the current commutation in the DGRCTs. Subsequently, a DGRCT prototype is fabricated, and experiments are conducted to measure the inductance along the current commutation loop (CCL) of the prototype DGRCT. Finally, a large current interruption experiment is conducted. The results show that the prototype DGRCT reduced the parasitic inductance within the CCL by at least 20% compared to conventional GCTs with single-gate ring design. The maximum current interruption capacity of the prototype DGRCT is no less than 12 kA at T = 300 K, which approaches the fault current interruption requirement in DCB applications for both transmission and distribution levels of dc power systems. [ABSTRACT FROM AUTHOR]

This paper aims to establish a novel and highly sensitive method to detect circulating tumor cells (CTCs) in the peripheral blood of patients with lung cancer. This therefore enables the discovery of invisible micrometastasis in the early stage of lung cancer, leading to better prognostic assessments of lung cancer and detection of the post-operative tumor recurrence and metastasis, treatment options, and evaluation of curative effects. In this research study, various lung cancer cells were mixed with adult blood samples to simulate blood samples of tumor patients. With novel test methods, CTCs in peripheral blood of lung cancer patients were calculated, after the reaction between the cells obtained from the mix and EpCAM (epithelial cell adhesion molecule) antibodies which were marked by immunomagnetic beads. The results showed that 18 out of 42 (42.9%) lung cancer patients had a positive CTCs, which increased with tumor enlargement or metastasis. CTCs were not detected in a total of 20 blood samples from healthy volunteers. This indicated that the technology of novel immunomagnetic bead-enrichment could effectively separate and identify CTCs in peripheral blood of lung cancer patients, which is of great clinical value for prognostic assessments and treatment guidance of lung cancer. [ABSTRACT FROM AUTHOR]

Carbon/aramid fabric composite coatings modified with boron nitride of single layer were fabricated through a dip-coating method. The composite coatings were cured with successive heating processes in an oven. The friction and wear properties of those as-prepared coatings were studied on a block-on-ring tester. The obtained results showed that the wear life of the coatings increased obviously after inclusion of boron nitride of single layer; however, the values of friction coefficients of the coatings almost remained constant. The optimal loadings of boron nitride of single layer in our experiments was 5 wt.%, and the wear life of the modified coating increased by ca. 360% compared with that of pristine fabric composite coating. The worn morphology of the sliding surface for both pristine fabric coating and the composite coatings filled with boron nitride of single layer was discussed, and the wear mechanisms were illuminated. [ABSTRACT FROM AUTHOR]

A scheme to enhance the optical delay in Rydberg atoms is proposed. In the linear case, the optical delay in a four-level system can be significantly enhanced compared to that of the three-level system. However, the width of the transparent window will decrease with an increase in the optical delay. In the nonlinear case, the nonlinear dispersion becomes steep around the transparency window. The enhanced cross-Kerr nonlinearity mainly contributes to the effective dispersion, which dramatically increases the optical delay. The simulation result shows that the optical delay of the system could be enhanced tens of times; moreover, the wide transparency window remains. So the delay-bandwidth product could be significantly improved due to nonlinear dispersion. We further examine Gaussian pulse propagation in the Rydberg atoms.

A white light cavity (WLC) scheme is proposed to achieve broadband response in the terahertz (THz) region by enhanced nonlinear dispersion in a magnetized graphene system. In the weak probe field limit, the cavity linewidth is narrowed due to electromagnetically induced transparency, and then it becomes nearly as broad as the empty-cavity linewidth under the condition of Autler-Towns splitting. It is interesting to find that the cavity linewidth can be further broadened by enhanced nonlinear dispersion. The simulation result shows that the response range of the cavity is from 6.273 THz to 6.308 THz under the given condition, which is nearly 11 times larger than the empty-cavity linewidth. Furthermore, the improvement in cavity transmission and the response of WLC at different frequencies are investigated.

MicroRNAs have been reported to play an important role in diverse biological processes and progression of various cancers. MicroRNA-29a has been observed to be downregulated in human lung cancer tissues, but the function of microRNA-29a in lung cancer has not been well investigated. In this study, we demonstrated that the expression levels of microRNA-29a were significantly downregulated in 38 pairs of lung cancer tissues when compared to adjacent normal tissues. Overexpression of microRNA-29a inhibited the activity of cell proliferation and colony formation of lung cancer cells, H1299 and A549. Furthermore, microRNA-29a targeted NRAS proto-oncogene in lung cancer cells. In human clinical specimens, NRAS proto-oncogene was highly expressed in human lung cancer tissues compared to normal tissues. More interestingly, microRNA-29a also sensitizes lung cancer cells to cisplatin (CDDP[Please replace "CDDP" with its expansion in the abstract and also provide expansion for the same in its first occurrence in text, if appropriate.]) via its target, NRAS proto-oncogene. Thus, our results in this study demonstrated that microRNA-29a acted as a tumor suppressor microRNA, which indicated potential application of microRNAs for the treatment of human lung cancer in the future.