Bacterial toxin‐antitoxin (TA) system has gained attention for its essential roles in cellular maintenance and survival under harsh environmental conditions such as nutrient deficiency and antibiotic treatment. There are at least 14 TA systems in Salmonella enterica serovar Typhimurium LT2, a pathogenic bacterium, and none of the structures of these TA systems have been determined. We determined the crystal structure of the VapBC TA complex from S. Typhimurium LT2 in proteolyzed and DNA‐bound forms at 2.0 Å and 2.8 Å resolution, respectively. The VapC toxin possesses a pilT N‐terminal domain (PIN‐domain) that shows ribonuclease activity, and the VapB antitoxin has an AbrB‐type DNA binding domain. In addition, the structure revealed details of interaction mode between VapBC and the cognate promoter DNA, including the inhibition of VapC by VapB and linear conformation of bound DNA in the VapBC complex. The complexation of VapBC with the linear DNA is not consistent with known structures of VapBC homologs in complex with bent DNA. We also identified VapC from S. Typhimurium LT2 as a putative Ca2+‐dependent ribonuclease, which differs from previous data showing that VapC homologs have Mg2+ or Mn2+‐dependent ribonuclease activities. The present studies could provide structural understanding of the physiology of VapBC systems and foundation for the development of new antibiotic drugs against Salmonella infection.

In order to suppress the malfunction caused by the negative Vth of oxide TFTs the shift register consists of double gate TFTs to control the Vth by adjusting top gate bias. The proposed circuit can detect the current consumption of the shift register so that we can hold the current consumption of the shift‐register with accordance with the desired current consumptions in the shift‐register. The system includes the compensation algorithm which can search an optimized top gate bias in the various circumstances, such as the process fluctuation and ambient temperature. The proposed system provided more stable operation than conventional one at high temperature. Experimental results showed that an output voltage of the shift‐register was deteriorated at 80 °C and power consumption doubled during 6 hours at 60 °C in the conventional system. On the other hand, the proposed system can provide the stable gate output up to 100 °C and kept the initial power consumption by adjusting the top gate bias.

Write pole-tip protrusion (PTP) effect on the overwrite performance at high recording data rate is discussed. It is shown that the head thermal expansion during the write process may lead to the degradation of overwrite value at high recording data rate. Overwrite degradation is caused by head-disk interactions when a high-frequency pattern is written. Appropriate selection of the disk lubricant can reduce the effect of the write PTP and increase the write current setting margin. At elevated drive temperatures, excessive PTP can cause head-disk interface failure. A write timing method allowing for the recording head to cool between the write cycles is proposed. A method of head-disk interface testing and a method of mapping the head-disk interactions are further described.Index Terms-Head-disk interactions mapping, overwrite degradation, write thermal pole-tip protrusion.

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The thickness of carbon overcoats has been reduced to 30 Å or less to achieve high areal density in magnetic media. Presently, technologies such as ion beam deposition and plasma enhanced chemical vapor deposition (PECVD) produce thin carbon overcoats with a high fraction of sp 3 bonding. These hard and dense overcoats exhibit good wear durability and corrosion resistance. This paper discusses processing, characterization, and tribological and corrosion performance of ultrathin overcoats (30 Å or less) produced by PECVD. The physical and chemical properties of the carbon overcoat affect the carbon-lubricant bonding, which subsequently determines the head-disk interaction. Since optimal properties of the carbon vary at the lubricant and magnetic layer interfaces, an interfacial functionality approach is needed for the design of thin overcoats. Functionalized carbon overcoat is a design that consists of a PECVD carbon layer with a sputtered functional layer on top. Characterization and tribological performance and comparison of functionalized carbon overcoat with PECVD carbon is also presented.