A method to monitor IGBT module bond wire failure using on-state voltage separation strategy

On-state voltage is an important thermal parameter for insulated gate bipolar transistor (IGBT) modules. It is employed widely to predict failure in IGBT module bond wires. However, due to restrictions in work environments and measurement methods, it is difficult to ensure the measurement accuracy for the on-state voltage under practical working conditions. To address this problem, an on-state voltage separation strategy is proposed for the IGBT modules with respect to the influence of collector current (Ic) and junction temperature (Tj). This method involves the separation of the on-state voltage into a dependent part and two independent parts during the IGBT module bond wire prediction. Based on the proposed separation strategy, the independent parts in the failure prediction can be removed, making it possible to directly monitor the voltage variations caused by bond wire failure. The experimental results demonstrate that the proposed diagnosis strategy can accurately predict the bond wire failure stage in an IGBT module under different conditions

Phase transition of multi-component (TiZrVNb)C ceramics—Part II: From single phase to multiple phases via adjusting V content

To address the relatively mediocre mechanical properties of single-phase multi-component carbide ceramics, a phase transition from a single phase to multiple phases was proposed to achieve superior mechanical properties. A series of (TiZrVxNb)C0.8 ceramics with different V contents were fabricated by spark plasma sintering (SPS). The influence of the V content on the phase composition, microstructural evolution, and mechanical properties was investigated in detail. The transition behavior from a single phase to multiple phases is discovered and discussed. The formation of the Zr-rich phase and Zr-poor phase can be attributed to the increase in lattice distortion and mixed enthalpy caused by the addition of V. A nanometer lamellar structure with a semi-coherent interface obtained via in situ decomposition is reported for the first time in multi-component carbide ceramics. The semi-coherent interfaces with high dislocation density and strain concentration effectively improve the mechanical properties, grain refinement, and multi-phase formation. The optimal comprehensive mechanical properties of the Vickers hardness (26.3 GPa), flexural strength (369 MPa), and fracture toughness (3.1 MPa·m1/2) were achieved for the sample with 20 mol% V

Phase transition of multi-component (TiZrVNb)C ceramics—Part I: Phase decomposition induced by carbon content

Phase decomposition can effectively enhance the mechanical properties of carbide ceramics and can overcome the difficulty of enhancing the mechanical properties of single-phase multicomponent carbide ceramics. In this work, a series of nonstoichiometric (TiZrVNb)Cx ceramics were prepared by spark plasma sintering (SPS) at different temperatures. The effects of the carbon content on the phase composition, microstructure evolution, and mechanical properties were investigated in detail. Phase decomposition occurred with decreasing carbon content. Two different solid solutions of (Ti,V)-rich and Zr-rich phases formed from the decomposition of equimolar single-phase solid solutions, namely, the Zr-poor phase and Zr-rich phase, respectively. The distribution of Nb element is relatively uniform. The semicoherent interfaces between the Zr-poor phase and the Zr-rich phase can harden and strengthen effectively under the synergistic effect of grain refinement. Ceramics with phase decomposition structures have apparent advantages compared to single-phase high-entropy carbides. This work provides an important train of thought for the microstructure tailoring and properties optimization of multi-component carbide ceramics

MicroRNA-9 as Potential Biomarker for Breast Cancer Local Recurrence and Tumor Estrogen Receptor Status

MicroRNAs (miRs) are small, non-protein coding transcripts involved in many cellular functions. Many miRs have emerged as important cancer biomarkers. In the present study, we investigated whether miR levels in breast tumors are predictive of breast cancer local recurrence (LR). Sixty-eight women who were diagnosed with breast cancer at the Lombardi Comprehensive Cancer Center were included in this study. Breast cancer patients with LR and those without LR were matched on year of surgery, age at diagnosis, and type of surgery. Candidate miRs were identified by screening the expression levels of 754 human miRs using miR arrays in 16 breast tumor samples from 8 cases with LR and 8 cases without LR. Eight candidate miRs that showed significant differences between tumors with and without LR were further verified in 52 tumor samples using real-time PCR. Higher expression of miR-9 was significantly associated with breast cancer LR in all cases as well as the subset of estrogen receptor (ER) positive cases (p = 0.02). The AUCs (Area Under Curve) of receiver operating characteristic (ROC) curves of miR-9 for all tumors and ER positive tumors are 0.68 (p = 0.02) and 0.69 (p = 0.02), respectively. In ER positive cases, Kaplan-Meier analysis showed that patients with lower miR-9 levels had significantly better 10-year LR-free survival (67.9% vs 30.8%, p = 0.02). Expression levels of miR-9 and another miR candidate, miR-375, were also strongly associated with ER status (p<0.001 for both). The potential of miR-9 as a biomarker for LR warrants further investigation with larger sample size

A Model of the On-State Voltage across IGBT Modules Based on Physical Structure and Conduction Mechanisms

The on-state voltage is an important electrical parameter of insulated gate bipolar transistor (IGBT) modules. Due to limits in instrumentation and methods, it is difficult to ensure accurate measurements of the on-state voltage in practical working conditions. Based on the physical structure and conduction mechanism of the IGBT module, this paper models the on-state voltage and gives a detailed method for extracting the on-state voltage. Experiments not only demonstrate the feasibility of the on-state voltage separation method but also suggest a method for measuring and extracting the model parameters. Furthermore, on-state voltage measurements and simulation results certified the accuracy of this method

Ultrastable Co-NC membrane for sterilization of Escherichia coli in flowing water

Abstract Advanced oxidation technology based on peroxonosulfate (PMS) has attracted extensive attention in water treatment research due to its fast reaction speed and wide pH range adaptability. Cobalt-based catalysts are considered to be one of the most effective reagents for PMS activation in various PMS activation methods. However, Co-ion leaching and difficulty in recovery have greatly hindered its practical applications. Herein, we developed a robust membrane constructed by nitrogen-doped carbon nanotubes embedded with cobalt nanoparticles (Co-NC) to concurrently address the Co-ion leaching and recovery issues. Based on our customization, continuous water flow reactor, the Co-NC membrane exhibited excellent catalytic activity and stability, in which it demonstrated a remarkable sterilization efficiency of 99.9999% against E. coli, and it retained a superior stability of 96.29% after 40 repeated cycles. Fewer attempts to put such efficient heterogeneous advanced oxidation processes (AOPs) into practical application, to mimic real-life applications, the performance of the Co-NC/PMS system was extended to the water taken from Qiuxi River. Remarkably, there is no deterioration in performance over 12 h of continuous real sewage processing. Mechanistic studies revealed that abundant high-valence metals (CoIV=O) were generated in the system, which can attack and penetrate into the cell membrane to destroy its intracellular defense system. This work provides useful insights into designing robust membranes with superior efficiency and stability for PMS-based advanced oxidation technology