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Microscopic and electronic roles of B in CoFeB-based magnetic tunnel junctions
Han, Yoonsung,Han, Jinhee,Choi, Hyoung Joon,Shin, Hyun-Joon,Hong, Jongill Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.38
<P>The giant tunneling magnetoresistance (TMR) in lattice-matched crystalline magnetic tunnel junctions (MTJs) strongly depends on the majority-spin Δ<SUB>1</SUB> bands of ferromagnetic electrodes. Our synchrotron radiation X-ray photoelectron spectroscopy and first-principles calculations show that B atoms suppress the formation of CoFe–O during CoFeB deposition in CoFeB/MgO/CoFeB MTJs, thereby lessening an effect that significantly degrades the majority-spin Δ<SUB>1</SUB> bands, and that CoFe–B has properties superior to CoFe–O in electron conduction in the majority-spin Δ<SUB>1</SUB> bands. During annealing, some of the B in CoFeB diffuses out, enhancing the valence bands of metallic CoFe, which improves the TMR value even further. Our present work elucidates the microscopic and electronic roles of B in MgO MTJs with CoFeB electrodes.</P> <P>Graphic Abstract</P><P>Our synchrotron radiation X-ray photoelectron spectroscopy and first-principles calculations show that B atoms suppress the formation of CoFe–O during CoFeB deposition in CoFeB/MgO/CoFeB MTJs, thereby lessening an effect that significantly degrades the majority-spin Δ<SUB>1</SUB> bands, and that CoFe–B has properties superior to CoFe–O in electron conduction in the majority-spin Δ<SUB>1</SUB> bands. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1jm12096d'> </P>
( Han Heom Na ),( Hee Jung Noh ),( Hyang Min Cheong ),( Yoonsung Kang ),( Keun Cheol Kim ) 생화학분자생물학회(구 한국생화학분자생물학회) 2016 BMB Reports Vol.49 No.4
The efficacy of anticancer drugs depends on a variety of signaling pathways, which can be positively or negatively regulated. In this study, we show that SETDB1 HMTase is down-regulated at the transcriptional level by several anticancer drugs, due to its inherent instability. Using RNA sequence analysis, we identified FosB as being regulated by SETDB1 during anticancer drug therapy. FosB expression was increased by treatment with doxorubicin, taxol and siSETDB1. Moreover, FosB was associated with an increased rate of proliferation. Combinatory transfection of siFosB and siSETDB1 was slightly increased compared to transfection of siFosB. Furthermore, FosB was regulated by multiple kinase pathways. ChIP analysis showed that SETDB1 and H3K9me3 interact with a specific region of the FosB promoter. These results suggest that SETDB1- mediated FosB expression is a common molecular phenomenon, and might be a novel pathway responsible for the increase in cell proliferation that frequently occurs during anticancer drug therapy. [BMB Reports 2016; 49(4): 238-243]
사람 핵DNA로부터 FosB 유전자 프로모터 클로닝 및 활성도 분석
나한흠(Han-Heom Na),강윤성(Yoonsung Kang),김근철(Keun-Cheol Kim) 한국생명과학회 2017 생명과학회지 Vol.27 No.8
FosB (FBJ murine osteosarcoma viral oncogene homolog B) 유전자는 사람의 19번 염색체에 위치하고 있으며 약 43 KD의 단백질을 코딩하며, 발생 및 분화과정, 개체 유지, 발병 진행 등을 조절한다고 알려져 왔다. 본 연구에서는 바이오 마커 등의 가능성이 있다고 보고된 FosB 유전자의 프로모터를 클로닝하여 활성도를 분석하고자 하였다. FosB genomic DNA 서열을 확인한 결과, TSS upstream 방향의 약 1 Kb 안쪽 부위에 FosB 유전자 발현을 위한 중요한 요소들이 있을 것으로 추정하였고, 따라서 FosB genomic DNA의 upstream -1,555 부위부터 exon 1의 +73까지 부위에 대한 PCR 증폭을 수행하였다. 또한 클로닝 성공을 높이기 위하여 일차로 TA-1<SUP>st</SUP>FosBp plasmid를 얻은 후, 다시 TA-1stFosBp plasmid를 template로 Kpn1과 Nhe1 제한 효소 절단부위를 프라이머에 삽입한 후 제작하여 2차 PCR을 수행하였으며, TA-2<SUP>nd</SUP>FosBp 플라스미드를 제작한 후 제한 효소로 절단하여 pGL3-luc vector로 subcloning하였다. 제작된 pGL3-FosBp-luc를 이용하여 항암제에 대한 활성도를 분석하고자 A549 사람 폐암세포주에 pGL3-FosBp-luc 플라스미드를 transfection 한 후 luciferase 활성도 분석을 수행하였다. Luciferase 활성도 증가는 doxorubicin, taxol 등을 처리한 후 단백질 발현 양상과 비교 하였을 때도 일치되는 결과를 얻을 수 있었다. 그러므로 FosB프로모터 클로닝은 향후 유전자 발현 연구, 마커분석 등에 유용할 것으로 사료된다. The FBJ murine osteosarcoma viral oncogene homolog B (FosB) gene is located at chromosome 19, and encodes 43 Kda protein. Functionally, the FosB gene is important for differentiation, development, and pathogenesis. Furthermore, the FosB gene is suggested as possible biomarker for tracing disease prognosis. In this study, we constructed plasmid containing a FosB promoter region and evaluate its promoter activity. We analyzed the putative promoter region in FosB genomic DNA using bioinformatics program, and we found important regulatory elements in 1 Kb upstream from transcription start site (TSS). Therefore, we performed polymerase chain reaction (PCR) amplification on region from-1,555 upstream to +73 of the FosB genomic DNA, and PCR product was inserted into TA vector to create the TA-1stFosBp plasmid. We then prepared the primer sets, which contain a restriction enzyme site for Kpn1 and Nhe1, in order to reinsert into the TA vector to prepare TA-2<SUP>nd</SUP> FosBp plasmid. It was finally subcloned into pGL3-luc vector after enzyme cutting. To evaluate whether the cloned plasmid is useful in cell based experiment, we performed luciferase assay with pGL3-FosBp-luctransfection. FosB promoter activity was increased compared to empty vector, and this activity was significantly increased by treatment of doxorubicin and taxol. We obtained consistent data on regulation of FosB gene expression after anticancer drug treatment using Western blot analysis. The results suggest that promoter cloning of the human FosB gene is very useful for studying gene expression and analyzing biomarkers.
Poly(acrylate-co-vinylacetate) Adhesive Patch for Sustained Dermal Delivery of Vitamin A
Nam, YoonSung,Kim, JuWon,Han, SangHoon,Chang, IhSeop 한국공업화학회 2003 Journal of Industrial and Engineering Chemistry Vol.9 No.2
An adhesive patch-type delivery system is suggested for sustained dermal application of vitamin A. Poly(acrylate-co-vinylacetate) was used as a pressure-sensitive adhesive. In vivo skin permeation of vitamin A from the patch was studied and compared with that of a conventional oil-in-water cream. The patch was found to enable to prolong the skin permeation of vitamin A, whereas the cream showed an initial burst skin absorption. The relative vitamin A bioavailability of the patch was about 76.9%, compared with that of the cream. Patches were less irritable to skin than the cream when the same amount of vitamin A was loaded. The lower skin irritancy might be due to the sustained release of vitamin A from the patch matrix. Silicon replica analysis was carried out as a clinical study to quantify the effects of the vitamin A patch on cutaneous relief. Repeated application of vitamin A-loaded patches onto crow's feet wrinkles for 12 weeks resulted in a reduction of the total surface area and the length of the wrinkles by up to 23% and 17%, respectively, without irritation.
Lee, Soogil,Han, Yoonsung,Kim, Sanghoon,Hong, Jongill American Institute of Physics 2009 JOURNAL OF APPLIED PHYSICS - Vol.105 No.7
<P>By investigating angular dependence of resistance and applying the Boltzmann distribution to the anisotropy dispersion of the magnetization in an exchange-biased pinned layer, we quantized the intrinsic anisotropy dispersion sigma(gamma) of spin valves. The sigma(gamma) was estimated to be 0.412 degrees for the as-deposited spin valve and 0.183 degrees for the ion-irradiated spin valve. This indicates that the dispersion indeed narrowed when the spin valve was field-annealed or irradiated by 550 eV hydrogen ions under a magnetic field, which is consistent with our previous attribution to the significant improvement in both exchange anisotropy and giant magnetoresistance of spin valves thus treated. Our methodology can be applied for other spin devices characterized by angular dependence of resistance to determine useful device properties such as the intrinsic anisotropy dispersion and the exchange bias of the exchange-biased reference layer. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3072776]</P>
Jangsik In,Yoonsung Han,Sunghoon Kim,Jaechul Shim,Jongill Hong 한국자기학회 2006 Journal of Magnetics Vol.11 No.3
We successfully enhanced the performance of a spin valve by inserting an ultra-thin layer of partially oxidized Fe in the pinned and free layers. With the exchange bias field kept large, the spin valve reached a GMR of 12%, which corresponded to a 55% increase in GMR when we compared it with that of spin valves without any inserted layer. The layer of partially oxidized Fe was more effective for improving the properties of the spin valve than the layer of partially oxidized Co??Fe₁?. Considering all the results, we can contribute the significant improvement to the combined effect of the modified local electronic structures at the Fe impurities and the enhanced spin-dependent reflections at the α-Fe₂O₃ phase in the magnetic layer.
1 ns 이하의 자화 용이축 펄스 자기장에 의한 자성박막의 자화 반전 거동
이진원(Jinwon Lee),한윤성(Yoonsung Han),이상호(Sangho Lee),홍종일(Jongill Hong) 한국자기학회 2007 韓國磁氣學會誌 Vol.17 No.5
We simulated the magnetization reversal behavior of submicron-thickness magnetic films by applying pulses of sub-ns-long durations and amplitudes along the easy axis. The films were rectangular and elliptical Ni??Fe₂?, and their thickness was 2 ㎚ and 4 ㎚. We observed different behaviors depending upon the shape and thickness of the films and found a normal non-switching in regions in which we expected complete switching after relaxation. In the elliptical film, the non-switching regions were found to be random and to be widely distributed throughout the switching map. The strong demagnetization field along the z-axis, the film thickness direction, is likely responsible for this abnormal behavior. In the rectangular film, the abnormal non-switching regions were less distributed than they were in the elliptical film due to edge domains resulting from the small M<SUB>z</SUB> or demagnetization field during the switching. Our simulation confirms that large demagnetization is detrimental to the ultra-fast magnetization reversal of magnetic ultra-thin films.