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As process technology is scaling down, timing speculation techniques such as Razor and STEP are emerged as alternative solutions to reduce required margins due to various variation effects. Unlike Razor, STEP is a prediction-based timing speculation method to predict suspicious timing errors before they really appear, and thus it can result in more performance improvement. Therefore, an improved monitoring-path selection algorithm for STEP-based timing speculation is proposed in this paper, in which candidate monitoring-paths are selected based on short path removement and path length estimation. Experimental results show that the proposed algorithm realizes an average of 1.71X overclocking compared with worst-case based designs.

As process technologies advance, the importance of timing error correction techniques is increasing as well. In this paper, We propose an area-overhead-oriented monitoring-path selection algorithm for suspicious timing error prediction circuits (STEPCs). STEPC predicts timing errors by monitoring the middle points of several speed-paths in a circuit. However, we need many STEPCs with a high area overhead to predict timing errors in an overall circuit. Our proposed method moves the STEPC insertion positions to minimize the number of inserted STEPCs. We apply a max-flow and min-cut approach to determine the optimal positions of inserted STEPCs. Our proposed algorithm reduces the required number of STEPCs to 1/19 and their area to 1/5 compared with a naive algorithm. Furthermore, our algorithm realizes 2.25X overclocking compared with just inserting STEPCs into several speed-paths.

The bio-nanocapsules (BNCs) composed of the recombinant envelope L-protein of hepatitis B virus constitute efficient delivery vectors specifically targeting human hepatocytes. Here, we have tried to enhance the stability of the BNCs because the L-proteins in the BNCs were aggregated due to random disulfide bridging when stored for a long period at 4 degrees C. The envelope protein contains fourteen cysteine residues in the S domain. Aggregation of the envelope proteins might be avoided if unessential cysteine residues are replaced or removed because the irreversible alkylation of the free sulfhydryl group protects against the aggregation and enhances the efficiency of encapsulation. In this study, the possibility of reducing the number of cysteine residues in the S domain to enhance the stability of the BNCs was assessed. The replacement of each cysteine residue by site-directed mutation showed that nine of fourteen cysteine residues were not essential to obtaining BNCs secreted into the culture media. Furthermore, upon evaluating the combination of these mutations, it was found that eight residues of replacement were acceptable. The mutant BNCs with replaced eight cysteine residues were not only more resistant against trypsin, but also more effective in transducing genes into human hepatoma-derived HepG2 cells than the original type BNC. Thus, we demonstrated that the minimized number of cysteine residues in the S domain could enhance the stability of the BNCs.