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RISS 인기검색어
- 검색키워드
- 저자 : Ignatova, Desislava (검색결과 3 건)
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Post annealing effect on ultra-thin Hf-based high-k gate oxides on Si
Joo-Hyung Kim,Velislava A. Ignatova,Peter Kücher,Martin Weisheit,Ehrenfried Zschech 한국물리학회 2009 Current Applied Physics Vol.9 No.2
We investigated the effect of post annealing on the electrical and physical properties of atomic-layerdeposited thin HfO2, HfSixOy and HfOyNz gate oxide films on Si. It was found that the main leakage conduction of all Hf-based oxide films was of the Poole–Frenkel (P–F) type in low electric fields and Fowler– Nordheim (F–N) conduction in higher fields. Also, it was observed that the transition from P–F to F–N of the annealed HfOyNz sample occurred earlier than that of the as-grown one. By using spectroscopic ellipsometry, it was found that the annealing process decreased the band gap of HfO2, HfSixOy and HfOyNz films. From depth profile measurements on the HfOyNz film, we conclude that N moves toward the surface and interface during annealing. We investigated the effect of post annealing on the electrical and physical properties of atomic-layerdeposited thin HfO2, HfSixOy and HfOyNz gate oxide films on Si. It was found that the main leakage conduction of all Hf-based oxide films was of the Poole–Frenkel (P–F) type in low electric fields and Fowler– Nordheim (F–N) conduction in higher fields. Also, it was observed that the transition from P–F to F–N of the annealed HfOyNz sample occurred earlier than that of the as-grown one. By using spectroscopic ellipsometry, it was found that the annealing process decreased the band gap of HfO2, HfSixOy and HfOyNz films. From depth profile measurements on the HfOyNz film, we conclude that N moves toward the surface and interface during annealing.
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Thermal Imidization Peculiarities of Electrospun BPDA-PDA/ODA Copolyamic Acid Nanofibers
Laura Peciulyte,Ramune Rutkaite,Algirdas Zemaitaitis,Milena Ignatova,Iliya Rashkov,Nevena Manolova 한국고분자학회 2013 Macromolecular Research Vol.21 No.4
Copolyamic acid (coPAA) based on 4,4'-oxydianiline (ODA), p-phenylenediamine (PDA) and 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was synthesized in N,N-dimethylformamide (DMF). The preparation of continuous defect-free nanofibers from BPDA-PDA/ODA coPAA was achieved by electrospinning of its DMF solution. The average fiber diameter significantly increased from 385 to 590 nm on increasing the total polymer concentration of the spinning solutions from 5 to 7 wt%. The addition of dodecylethyldimethylammonium bromide (DEDAB) salt to the spinning solution resulted in the procurement of coPAA nanofibers with a much smaller (more than 3 times) average diameter. The coPAA imidization process was investigated through FTIR spectroscopy. The chemical composition and morphology of coPI nanofibers were assessed by X-ray photoelectron spectroscopy and scanning electron microscopy. Imidization under isothermal conditions proceeded faster in the first stage. Activation energies in the first and second imidization stages were similar when DEDAB had been added into the electrospinning solution. Cylindrical or crimped defect-free nanofibers of BPDA-PDA/ODA copolyimide (coPI) were obtained by the stepped thermal imidization of coPAA. The morphology of coPI nanofibers depends on the curing temperature. The crimped coPI nanofibers were most probably due to the relief of residual stress when the curing temperature was higher than the polymer glass transition temperature.
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Guenova, Emmanuella,Skabytska, Yuliya,Hoetzenecker, Wolfram,Weindl, Gü,nther,Sauer, Karin,Tham, Manuela,Kim, Kyu-Won,Park, Ji-Hyeon,Seo, Ji Hae,Ignatova, Desislava,Cozzio, Antonio,Levesque, Mitc National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.7
<P>Interleukin 4 (IL-4) can suppress delayed-type hypersensitivity reactions (DTHRs), including organ-specific autoimmune diseases in mice and humans. Despite the broadly documented antiinflammatory effect of IL-4, the underlying mode of action remains incompletely understood, as IL-4 also promotes IL-12 production by dendritic cells (DCs) and IFN-gamma-producing T(H)1 cells in vivo. Studying the impact of IL-4 on the polarization of human and mouse DCs, we found that IL-4 exerts opposing effects on the production of either IL-12 or IL-23. While promoting IL-12-producing capacity of DCs, IL-4 completely abrogates IL-23. Bone marrow chimeras proved that IL-4-mediated suppression of DTHRs relies on the signal transducer and activator of transcription 6 (STAT6)-dependent abrogation of IL-23 in antigen-presenting cells. Moreover, IL-4 therapy attenuated DTHRs by STAT6-and activating transcription factor 3 (ATF3)-dependent suppression of the IL-23/T(H)17 responses despite simultaneous enhancement of IL-12/T(H)1 responses. As IL-4 therapy also improves psoriasis in humans and suppresses IL-23/ T(H)17 responses without blocking IL-12/T(H)1, selective IL-4-mediated IL-23/T(H)17 silencing is promising as treatment against harmful inflammation, while sparing the IL-12-dependent T(H)1 responses.</P>
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