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A Study on Joint Resistance between Nb-Ti Superconducting Wires for MRI Magnet
Sang-Soo Oh,Yingming Dai,Dong-Woo Ha,Hyun-Man Jang,Kang-Sik Ryu 한국정보과학회 1997 Journal of Electrical Engineering and Information Vol.2 No.6
The joints between the superconducting wires are inevitably needed from the requirement of a high magnetic stability with respect to time in the superconducting MRI magnet. In this study, a new superconducting joint using Cu/Nb-Ti sleeve has been tried on the MR1 type Nb-Ti superconducting wires. The transformer induction type apparatus was made and applied to measure the joint resistance. A very low joint resistance of 10^(-15) Ω could be successfully obtained from this joint method. It was confirmed that the initial rapid current decay occurs before the very stable current decay due to only superconducting joint. Some unstable part in the joint like exposed filaments causes the initial induced current to lower and influence on the increase of the joint resistance.
MS/MS of Synthetic Peptide Is Not Sufficient to Confirm New Types of Protein Modifications
Lee, Sangkyu,Tan, Minjia,Dai, Lunzhi,Kwon, Oh Kwang,Yang, Jeong Soo,Zhao, Yingming,Chen, Yue American Chemical Society 2013 JOURNAL OF PROTEOME RESEARCH Vol.12 No.2
<P>Protein post-translational modification (PTM) is one of the major regulatory mechanisms that fine-tune protein functions. Undescribed mass shifts, which may suggest novel types of PTMs, continue to be discovered because of the availabilities of more sensitive mass spectrometry technologies and more powerful sequence alignment algorithms. In this study, the histone extracted from HeLa cells was analyzed using an approach that takes advantages of in vitro propionylation, efficient peptide separation using isoelectric focusing fractionation, and the high sensitivity of the linear ion trap coupled with hybrid FT mass spectrometer. One modified peptide was identified with a new type of protein modification (+42 Da), which was assigned to acetylation of threonine 15 in histone2A. The modified peptide was verified by careful manual evaluation of the tandem mass spectrum and confirmed by high-resolution MS/MS analysis of the corresponding synthetic peptide. However, HPLC coelution and MS/MS/MS of key ions showed that the +42 Da mass shifts at threonine residue did not correspond to acetylation. The key fragment ion, y4, in the MS/MS/MS spectra (indicative of the modification site) differed between the in vivo and synthetic peptide. We showed that the misidentification was originated from sequence homologues and chemical derivitization during sample preparation. This result indicated that a more stringent procedure that includes MS/MS, MS/MS/MS, and HPLC coelution of synthetic peptides is required to identify a new PTM.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jprobs/2013/jprobs.2013.12.issue-2/pr300667e/production/images/medium/pr-2012-00667e_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/pr300667e'>ACS Electronic Supporting Info</A></P>
Development of Strain Measurement in Superconducting Magnet Through Fiber Bragg Grating
Hongjie Zhang,Fanping Deng,Qiuliang Wang,Luguang Yan,Yingming Dai,Keeman Kim IEEE 2008 IEEE transactions on applied superconductivity Vol.18 No.2
<P>Temperature and strain responses of fiber Bragg grating sensors were measured in cryogenic environment. With temperature from room temperature down to 77 K or 4.2 K, the temperature response was found to be relatively linear above 100 K, and the temperature sensitivity decreases with the decrease of temperature, and to approximately zero for temperature less than 50 K. Technologies were developed to eliminate the multi-peaks in strain experiment, so the strain response was measured at 77 K, and was found to be linear at constant temperatures.</P>