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Racz AS, Kerner Z, Nemeth A, Panjan P, Peter L, Sulyok A, Vertesy G, Zolnai Z, Menyhard M. Corrosion Resistance of Nanosized Silicon Carbide-Rich Composite Coatings Produced by Noble Gas Ion Mixing. ACS Appl Mater Interfaces 2017; 9:44892-44899. [PMID: 29206438 DOI: 10.1021/acsami.7b14236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ion beam mixing has been used to produce a silicon carbide (SiC)-rich nanolayer for protective coating. Different C/Si/C/Si/C/Si(substrate) multilayer structures (with individual layer thicknesses falling in the range of 10-20 nm) have been irradiated by Ar+ and Xe+ ions at room temperature in the energy and fluence ranges of 40-120 keV and 1-6 × 1016 ion/cm2, respectively. The effects of ion irradiation, including the in-depth distribution of the SiC produced, was determined by Auger electron spectroscopy depth profiling. The thickness of the SiC-rich region was only some nanometers, and it could be tailored by changing the layer structure and the ion irradiation conditions. The corrosion resistance of the layers was investigated by potentiodynamic electrochemical test in 4 M KOH solution. The measured corrosion resistance of the SiC-rich layers was orders of magnitude better than that of pure silicon, and a correlation was found between the corrosion current density and the effective areal density of the SiC.
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Affiliation(s)
- A S Racz
- Institute for Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences , Konkoly Thege M. út 29-33, H-1121 Budapest, Hungary
| | - Z Kerner
- Institute for Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences , Konkoly Thege M. út 29-33, H-1121 Budapest, Hungary
| | - A Nemeth
- Wigner Research Centre for Physics, Hungarian Academy of Sciences , Konkoly-Thege M. út 29-33, H-1121 Budapest, Hungary
| | - P Panjan
- Jožef Stefan Institute , Jamova 39, 1000 Ljubljana, Slovenia
| | - L Peter
- Wigner Research Centre for Physics, Hungarian Academy of Sciences , Konkoly-Thege M. út 29-33, H-1121 Budapest, Hungary
| | - A Sulyok
- Institute for Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences , Konkoly Thege M. út 29-33, H-1121 Budapest, Hungary
| | - G Vertesy
- Institute for Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences , Konkoly Thege M. út 29-33, H-1121 Budapest, Hungary
| | - Z Zolnai
- Institute for Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences , Konkoly Thege M. út 29-33, H-1121 Budapest, Hungary
| | - M Menyhard
- Institute for Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences , Konkoly Thege M. út 29-33, H-1121 Budapest, Hungary
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Serényi M, Frigeri C, Csik A, Khánh NQ, Németh A, Zolnai Z. On the mechanisms of hydrogen-induced blistering in RF-sputtered amorphous Ge. CrystEngComm 2017. [DOI: 10.1039/c7ce00076f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Merkel DG, Bessas D, Zolnai Z, Rüffer R, Chumakov AI, Paddubrouskaya H, Van Haesendonck C, Nagy N, Tóth AL, Deák A. Evolution of magnetism on a curved nano-surface. Nanoscale 2015; 7:12878-12887. [PMID: 26162007 DOI: 10.1039/c5nr02928g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
To design custom magnetic nanostructures, it is indispensable to acquire precise knowledge about the systems in the nanoscale range where the magnetism forms. In this paper we present the effect of a curved surface on the evolution of magnetism in ultrathin iron films. Nominally 70 Å thick iron films were deposited in 9 steps on 3 different types of templates: (a) a monolayer of silica spheres with 25 nm diameter, (b) a monolayer of silica spheres with 400 nm diameter and (c) for comparison a flat silicon substrate. In situ iron evaporation took place in an ultrahigh vacuum chamber using the molecular beam epitaxy technique. After the evaporation steps, time differential nuclear forward scattering spectra, grazing incidence small angle X-ray scattering images and X-ray reflectivity curves were recorded. In order to reconstruct and visualize the magnetic moment configuration in the iron cap formed on top of the silica spheres, micromagnetic simulations were performed for all iron thicknesses. We found a great influence of the template topography on the onset of magnetism and on the developed magnetic nanostructure. We observed an individual magnetic behaviour for the 400 nm spheres which was modelled by vortex formation and a collective magnetic structure for the 25 nm spheres where magnetic domains spread over several particles. Depth selective nuclear forward scattering measurements showed that the formation of magnetism begins at the top region of the 400 nm spheres in contrast to the 25 nm particles where the magnetism first appears in the region where the spheres are in contact with each other.
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Affiliation(s)
- D G Merkel
- European Synchrotron Radiation Facility, F-38043, Grenoble, France.
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Albert E, Basa P, Deák A, Németh A, Osváth Z, Sáfrán G, Zolnai Z, Hórvölgyi Z, Nagy N. Introducing nanoscaled surface morphology and percolation barrier network into mesoporous silica coatings. RSC Adv 2015. [DOI: 10.1039/c5ra09357k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The advantages of surface pattern and mesoporous character of silica thin films were combined, while preserving the interconnected pore system or creating laterally separated porous volumes surrounded by nonpermeable compact zones.
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Affiliation(s)
- E. Albert
- Budapest University of Technology and Economics
- Department of Physical Chemistry and Materials Science
- H-1521 Budapest
- Hungary
| | - P. Basa
- Semilab Semiconductor Physics Laboratory Co. Ltd
- H-1117 Budapest
- Hungary
| | - A. Deák
- Hungarian Academy of Sciences
- Centre for Energy Research
- Institute of Technical Physics and Materials Science
- H-1525 Budapest
- Hungary
| | - A. Németh
- Hungarian Academy of Sciences
- Wigner Research Centre for Physics
- Institute for Particle and Nuclear Physics
- H-1525 Budapest
- Hungary
| | - Z. Osváth
- Hungarian Academy of Sciences
- Centre for Energy Research
- Institute of Technical Physics and Materials Science
- H-1525 Budapest
- Hungary
| | - G. Sáfrán
- Hungarian Academy of Sciences
- Centre for Energy Research
- Institute of Technical Physics and Materials Science
- H-1525 Budapest
- Hungary
| | - Z. Zolnai
- Hungarian Academy of Sciences
- Centre for Energy Research
- Institute of Technical Physics and Materials Science
- H-1525 Budapest
- Hungary
| | - Z. Hórvölgyi
- Budapest University of Technology and Economics
- Department of Physical Chemistry and Materials Science
- H-1521 Budapest
- Hungary
| | - N. Nagy
- Hungarian Academy of Sciences
- Centre for Energy Research
- Institute of Technical Physics and Materials Science
- H-1525 Budapest
- Hungary
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Albert E, Albouy PA, Ayral A, Basa P, Csík G, Nagy N, Roualdès S, Rouessac V, Sáfrán G, Suhajda Á, Zolnai Z, Hórvölgyi Z. Antibacterial properties of Ag–TiO2 composite sol–gel coatings. RSC Adv 2015. [DOI: 10.1039/c5ra05990a] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This study reveals the connection between the silver-doping method, the resulting nature and amount of the silver dopant together with the structural properties and the long-term antibacterial activity of composite coatings.
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Lasala R, Coudray N, Abdine A, Zhang Z, Lopez-Redondo M, Kirshenbaum R, Alexopoulos J, Zolnai Z, Stokes DL, Ubarretxena-Belandia I. Sparse and incomplete factorial matrices to screen membrane protein 2D crystallization. J Struct Biol 2014; 189:123-34. [PMID: 25478971 DOI: 10.1016/j.jsb.2014.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 11/18/2014] [Accepted: 11/24/2014] [Indexed: 01/09/2023]
Abstract
Electron crystallography is well suited for studying the structure of membrane proteins in their native lipid bilayer environment. This technique relies on electron cryomicroscopy of two-dimensional (2D) crystals, grown generally by reconstitution of purified membrane proteins into proteoliposomes under conditions favoring the formation of well-ordered lattices. Growing these crystals presents one of the major hurdles in the application of this technique. To identify conditions favoring crystallization a wide range of factors that can lead to a vast matrix of possible reagent combinations must be screened. However, in 2D crystallization these factors have traditionally been surveyed in a relatively limited fashion. To address this problem we carried out a detailed analysis of published 2D crystallization conditions for 12 β-barrel and 138 α-helical membrane proteins. From this analysis we identified the most successful conditions and applied them in the design of new sparse and incomplete factorial matrices to screen membrane protein 2D crystallization. Using these matrices we have run 19 crystallization screens for 16 different membrane proteins totaling over 1300 individual crystallization conditions. Six membrane proteins have yielded diffracting 2D crystals suitable for structure determination, indicating that these new matrices show promise to accelerate the success rate of membrane protein 2D crystallization.
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Affiliation(s)
- R Lasala
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA
| | - N Coudray
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA
| | - A Abdine
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, NY 10029, USA
| | - Z Zhang
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA
| | - M Lopez-Redondo
- Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - R Kirshenbaum
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, NY 10029, USA
| | - J Alexopoulos
- Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Z Zolnai
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - D L Stokes
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA; Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - I Ubarretxena-Belandia
- New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027, USA; Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, NY 10029, USA.
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Nagy N, Zolnai Z, Deák A, Fried M, Bársony I. Various nanostructures on macroscopically large areas prepared by tunable ion-swelling. J Nanosci Nanotechnol 2012; 12:6712-6717. [PMID: 22962811 DOI: 10.1166/jnn.2012.4538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Various nanostructures were fabricated by ion irradiation on large area (100) Si surfaces covered by colloidal Langmuir-Blodgett films as nanolithographic masks. The ordered structure of the Langmuir-Blodgett monolayer composed from spherical Stöber silica particles of 200 nm and 450 nm diameter offer the possibility to form local surface swelling patterns during the ion bombardment step. Utilizing the dependence of the surface morphology on the irradiation parameters the tunability of nanostructuring was studied for 40 keV Ar+ and 500 keV Xe2+ ions. We show that the periodicity of the resulted surface pattern is determined by the size of the masking particles, while the height of nanostructures can be tuned by the ion fluence. The quality of projection of the nanomask contours to the substrate-the contrast of masking-can be set by choosing appropriate ion energy, thereby determining the curvature of the surface pattern. Moreover, deformation of the nanomask due to ion-nanoparticle interactions should be taken into account since these effects can be also utilized for tailoring various structures. The silica masking layers before and after ion irradiation and the resulting Si surface patterns were investigated by field emission scanning electron microscopy and atomic force microscopy analysis.
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Affiliation(s)
- N Nagy
- Research Institute for Technical Physics and Materials Science (MFA), MTA, H-1525 Budapest, Hungary
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Abstract
We have analyzed cross-relaxation in fractionally deuterated molecules and showed that the full matrix analysis fails except when the dilution is extreme. This is because the isotopic dilution alters the matrix exponential relationship between the observed spectrum and the cross-relaxation rate constants sought. Consequently, an average of the spectra of various isotopomers differs from the matrix exponential of an average relaxation matrix. We have derived a series expansion that allows the determination of the cross-relaxation rate constants in arbitrarily deuterated molecules.
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Affiliation(s)
- Z Zolnai
- Department of Biochemistry and Molecular Biology, Mayo Graduate School, Mayo Clinic and Mayo Foundation, Rochester, MN, 55905, U.S.A
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Wang J, Truckses DM, Abildgaard F, Dzakula Z, Zolnai Z, Markley JL. Solution structures of staphylococcal nuclease from multidimensional, multinuclear NMR: nuclease-H124L and its ternary complex with Ca2+ and thymidine-3',5'-bisphosphate. J Biomol NMR 1997; 10:143-164. [PMID: 9369015 DOI: 10.1023/a:1018350004729] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The solution structures of staphylococcal nuclease (nuclease) H124L and its ternary complex, (nuclease-H124L).pdTp.Ca2+, were determined by ab initio dynamic simulated annealing using 1925 NOE, 119 phi, 20 chi 1 and 112 hydrogen bond constraints for the free protein, and 2003 NOE, 118 phi, 20 chi 1 and 114 hydrogen bond constraints for the ternary complex. In both cases, the final structures display only small deviations from idealized covalent geometry. In structured regions, the overall root-mean-square deviations from mean atomic coordinates are 0.46 (+/- 0.05) A and 0.41 (+/- 0.05) A for the backbone heavy atoms of nuclease and its ternary complex, respectively. The backbone conformations of residues in the loop formed by Arg81-Gly86, which is adjacent to the active site, are more precisely defined in the ternary complex than in unligated nuclease. Also, the protein side chains that show NOEs and evidence for hydrogen bonds to pdTp (Arg35, Lys84, Tyr85, Arg87, Tyr113, and Tyr115) are better defined in the ternary complex. As has been observed previously in the X-ray structures of nuclease-WT, the binding of pdTp causes the backbone of Tyr113 to change from an extended to a left-handed alpha-helical conformation. The NMR structures reported here were compared with available X-ray structures: nuclease-H124L [Truckses et al. (1996) Protein Sci., 5, 1907-1916] and the ternary complex of wild-type staphylococcal nuclease [Loll and Lattman (1989) Proteins Struct. Funct. Genet., 5, 183-201]. Overall, the solution structures of nuclease-H124L are consistent with these crystal structures, but small differences were observed between the structures in the solution and crystal environments. These included differences in the conformations of certain side chains, a reduction in the extent of helix 1 in solution, and many fewer hydrogen bonds involving side chains in solution.
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Affiliation(s)
- J Wang
- Department of Biochemistry, University of Wisconsin-Madison 53706, USA
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Juranić N, Zolnai Z, Macura S. Identification of spin diffusion pathways in proteins by isotope-assisted NMR cross-relaxation network editing. J Biomol NMR 1997; 9:317-322. [PMID: 9229504 DOI: 10.1023/a:1018639211400] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A new isotope-assisted cross-relaxation editing experiment, [1H-13C]DINE-NOESY[1H-15N]HSQC (DINE=Double INEPT Edited), is proposed. It is based on the selective inversion of CH/CH3 or CH2 protons in the middle of the mixing time. The experiment sorts out the spin diffusion paths according to the principal mediators, either the CH/CH3 or the CH2 protons. This is useful in the structure refinement process, as it enables proper alignment of the aliphatic protons in the vicinity of NH protons.
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Affiliation(s)
- N Juranić
- Department of Biochemistry and Molecular Biology, Mayo Graduate School, Mayo Clinic and Foundation, Rochester, MN 55905, USA
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