The Application of Approximate Entropy Theory in Defects Detecting of IGBT Module

Defect is one of the key factors in reducing the reliability of the insulated gate bipolar transistor (IGBT) module, so developing the diagnostic method for defects inside the IGBT module is an important measure to avoid catastrophic failure and improves the reliability of power electronic converters. For this reason, a novel diagnostic method based on the approximate entropy (ApEn) theory is presented in this paper, which can provide statistical diagnosis and allow the operator to replace defective IGBT modules timely. The proposed method is achieved by analyzing the cross ApEn of the gate voltages before and after the occurring of defects. Due to the local damage caused by aging, the intrinsic parasitic parameters of packaging materials or silicon chips inside the IGBT module such as parasitic inductances and capacitances may change over time, which will make remarkable variation in the gate voltage. That is to say the gate voltage is close coupled with the defects. Therefore, the variation is quantified and used as a precursor parameter to evaluate the health status of the IGBT module. Experimental results validate the correctness of the proposed method

Crystal Structure of EHEC Intimin: Insights into the Complementarity between EPEC and EHEC

Enterohaemorrhagic E. coli (EHEC) O157:H7 is a primary food-borne bacterial pathogen capable of causing life-threatening human infections which poses a serious challenge to public health worldwide. Intimin, the bacterial outer-membrane protein, plays a key role in the initiating process of EHEC infection. This activity is dependent upon translocation of the intimin receptor (Tir), the intimin binding partner of the bacteria-encoded host cell surface protein. Intimin has attracted considerable attention due to its potential function as an antibacterial drug target. Here, we report the crystal structure of the Tir-binding domain of intimin (Int188) from E. coli O157:H7 at 2.8 Å resolution, together with a mutant (IntN916Y) at 2.6 Å. We also built the structural model of EHEC intimin-Tir complex and analyzed the key binding residues. It suggested that the binding pattern of intimin and Tir between EHEC and Enteropathogenic E. coli (EPEC) adopt a similar mode and they can complement with each other. Detailed structural comparison indicates that there are four major points of structural variations between EHEC and EPEC intimins: one in Domain I (Ig-like domain), the other three located in Domain II (C-type lectin-like domain). These variations result in different binding affinities. These findings provide structural insight into the binding pattern of intimin to Tir and the molecular mechanism of EHEC O157: H7