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Vlasova D.D.,Kazan Physical Technical Institute | Kalachev A.A.,Kazan Federal University
Bulletin of the Russian Academy of Sciences: Physics | Year: 2012

The possibility of observing collective spontaneous emission upon a cooperative transition in an ensemble of interacting optical center pairs embedded in a metamaterial is investigated. It is shown that when the effective refractive index tends to zero, the relaxation rate of excited atomic states substantially decreases, allowing us to observe collective effects on weaker cooperative transitions. © Allerton Press, Inc., 2012.

Krushelnitsky A.,Kazan Institute of Biochemistry and Biophysics | Zinkevich T.,Kazan Physical Technical Institute | Reichert D.,Martin Luther University of Halle Wittenberg | Chevelkov V.,Leibniz Institute for Molecular Pharmacology | Reif B.,Leibniz Institute for Molecular Pharmacology
Journal of the American Chemical Society | Year: 2010

For the first time, we have demonstrated the site-resolved measurement of reliable (i.e., free of interfering effects) 15N R1ρ relaxation rates from a solid protein to extract dynamic information on the microsecond time scale. 15N R1ρ NMR relaxation rates were measured as a function of the residue number in a 15N, 2H-enriched (with 10-20% back-exchanged protons at labile sites) microcrystalline SH3 domain of chicken α-spectrin. The experiments were performed at different temperatures and at different spin-lock frequencies, which were realized by on- and off-resonance spin-lock irradiation. The results obtained indicate that the interfering spin-spin contribution to the R 1ρ rate in a perdeuterated protein is negligible even at low spin-lock fields, in contrast to the case for normal protonated samples. Through correlation plots, the R1ρ rates were compared with previous data for the same protein characterizing different kinds of internal mobility. © 2010 American Chemical Society.

Mozzhukhin G.V.,Gebze Institute of Technology | Rameev B.Z.,Gebze Institute of Technology | Rameev B.Z.,Kazan Physical Technical Institute | Khusnutdinov R.R.,Kazan Federal University | And 2 more authors.
Applied Magnetic Resonance | Year: 2012

New method of multifrequency nuclear quadrupole resonance (NQR) for the explosive detection has been proposed. This technique consists of application of the series of composite excitation circles, each consisting of two or three successive pulses of different frequencies. In this work, we study in detail the multipulse sequence consisting of n excitation sets, each set consists of three pulses. The first pulse is applied with frequency ν-, the second pulse with frequency ν0, and the third pulse with frequency ν-, but with a shifted phase. The NQR signal is detected at the frequency ν+. The maximal amplitude of the detected signal is obtained by tuning the pulse parameters at frequencies ν- and ν0. We have shown that the phase of the NQR signal at the frequency ν+ second part of the composite pulse with the frequency ν0 the signals with different phases to suppress the spurious signals. The method could be used for increasing the NQR signal, avoiding the spurious signals and improving the reliability of NQR detection. Possible applications of the method for the explosive detection are also discussed. © 2012 Springer-Verlag.

Malinsky P.,Academy of Sciences of the Czech Republic | Malinsky P.,Je Purkinje University | MacKova A.,Academy of Sciences of the Czech Republic | MacKova A.,Je Purkinje University | And 7 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2012

Polyimide (PI), polyetheretherketone (PEEK) and polyethyleneterephthalate (PET) were implanted with 40 keV Ni + ions at RT to the fluences (0.25-1.5) × 10 17 cm -2 at ion current density of 4 μA cm -2. Then some of the samples were annealed at the temperatures close to the polymer glassy transition temperature. Depth profiles of the Ni atoms in the as implanted and annealed samples were determined by RBS method. The profiles in the as implanted samples agree reasonably with those simulated using TRYDIN code. The implanted Ni atoms tend to aggregate into nano-particles, the size and distribution of which was determined from TEM images. The nano-particle size increases with increasing ion fluence. Subsequent annealing leads to a reduction in the nanoparticle size. The surface morphology of the implanted and annealed samples was studied using AFM. The changes in the polymer sheet resistance of the implanted and annealed samples were measured by standard two-point technique. The sheet resistance decreases with increasing temperature of annealing. © 2011 Elsevier B.V. All rights reserved.

Mackova A.,Academy of Sciences of the Czech Republic | Mackova A.,Je Purkinje University | Malinsky P.,Academy of Sciences of the Czech Republic | Malinsky P.,Je Purkinje University | And 8 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2013

The properties of implanted polymers strongly depend on the implantation ion fluence and on the properties of the implanted atoms. The stability of synthesized nano-structures during further technological steps like annealing is of importance for their possible applications. Polyimide (PI), polyetheretherketone (PEEK), and polyethyleneterephtalate (PET) were implanted with 40 keV Co+ ions at room temperature at fluences ranging from 0.2 × 1016 cm-2 to 1.0 × 1017 cm -2 and annealed at a temperature of 200 °C. The implanted depth profiles of as-implanted and annealed samples, determined by the RBS method, were compared with the results of SRIM 2012 simulations. The structural and compositional changes of the implanted and subsequently annealed polymers were characterized by RBS and UV-vis spectroscopy. The surface morphology of as-implanted and annealed samples was examined by the AFM method and their electrical properties by sheet resistance measurement. © 2013 Elsevier B.V. All rights reserved.

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