Search for: All records

This paper presents a new power grid network design and optimization technique that considers the new EM immortality constraint due to EM void saturation volume for multi-segment interconnects. Void may grow to its saturation volume without changing the wire resistance significantly. However, this phenomenon was ignored in existing EM-aware optimization methods. By considering this new effect, we can remove more conservativeness in the EM-aware on-chip power grid design. Along with recently proposed nucleation phase immortality constraint for multi-segment wires, we show that both EM immortality constraints can be naturally integrated into the existing programming based power grid optimization framework. To further mitigate the overly conservative problem of existing immortality-constrained optimization methods, we further explore two strategies: first we size up failed wires to meet one of immorality conditions subject to design rules; second, we consider the EM-induced aging effects on power supply networks for a targeted lifetime, which allows some short-lifetime wires to fail and optimizes the rest of the wires. Numerical results on a number of IBM and self-generated power supply networks demonstrate that the new method can reduce more power grid area compared to the existing EM-immortality constrained optimizations. Furthermore, the new method can optimize power grids with nucleated wires, which would not be possible with the existing methods. 

Di‐ubiquitin (diUB) conjugates of defined linkages are useful tools for probing the functions of UB ligases, UB‐binding proteins and deubiquitinating enzymes (DUBs) in coding, decoding and editing the signals carried by the UB chains. Here we developed an efficient method for linkage‐specific synthesis of diUB probes based on the incorporation of the unnatural amino acid (UAA)N^ϵ‐L‐thiaprolyl‐L‐Lys (L‐ThzK) into UB for ligation with another UB at a defined Lys position. The diUB formed by the UAA‐mediated ligation reaction has a G76C mutation on the side of donor UB for conjugation with E2 and E3 enzymes or undergoing dethiolation to generate a covalent trap for DUBs. The development of UAA mutagenesis for diUB synthesis provides an easy route for preparing linkage‐specific UB‐based probes to decipher the biological signals mediated by protein ubiquitination.