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Shatalov A.F.,Moscow State Institute of Radioengineering | Shatalov F.A.,Moscow State Institute of Radioengineering
Radiophysics and Quantum Electronics | Year: 2010

We study the pulse interval jitter of a passively and actively acousto-optically Q-switched solidstate laser. Diffraction and birefringent acousto-optical cells are considered as active Q-switches. Analytical expressions for the pulse interval jitter of a solid-state laser are obtained. The possibilities of jitter reduction are examined. © 2010 Springer Science+Business Media, Inc.

Seyedhosseini E.,University of Aveiro | Ivanov M.,University of Aveiro | Bystrov V.,University of Aveiro | Bystrov V.,Institute of Mathematical Problems of Biology | And 8 more authors.
Crystal Growth and Design | Year: 2014

Glycine is the simplest amino acid and one of the basic and important elements in biology, as it serves as a building block for proteins. The interest in this material has recently arisen from its useful functional properties, such as its high value of nonlinear optical susceptibility and ferroelectricity. Three polymorphic forms with different physical properties are possible in glycine, the most useful β-polymorph being much less stable than the other two. In this work, we could grow stable microcrystals of β-glycine using a (111)Pt/SiO2/Si substrate as a template. The effects of the solution concentration and Pt-assisted nucleation on the crystal growth and phase evolution were evaluated using X-ray diffraction analysis and Raman spectroscopy. A second harmonic generation (SHG) method confirmed that the 2-fold symmetry is preserved in as-grown crystals, thus reflecting the expected P21 symmetry of the β-phase. Spontaneous polarization direction is found to be parallel to the monoclinic [010] axis and directed along the crystal length. These data are confirmed by computational molecular modeling. Optical measurements revealed also relatively high values of the nonlinear optical susceptibility (50% greater than in the z-cut quartz). The potential use of stable β-glycine crystals in nonlinear optical applications is discussed. © 2014 American Chemical Society.

Amdursky N.,Tel Aviv University | Beker P.,Tel Aviv University | Koren I.,Tel Aviv University | Bank-Srour B.,Tel Aviv University | And 7 more authors.
Biomacromolecules | Year: 2011

Phase transitions in organic and inorgnic materials are well-studied classical phenomena, where a change in the crystal space group symmetry induces a wide variation of physical properties, permitted by the crystalline symmetry in each phase. Here we observe a conformational induced transition in bioinspired peptide nanotubes (PNTs). We found that the PNTs change their original molecular assembly from a linear peptide conformation to a cyclic one, followed by a change of the nanocrystalline structure from a noncentrosymmetric hexagonal space group to a centrosymmetric orthorhombic space group. The observed transition is irreversible and induces a profound variation in the PNTs properties, from the microscopic to the macroscopic level. In this context, we follow the unique changes in the molecular, morphological, piezoelectric, second harmonic generation, and wettability properties of the PNTs. © 2011 American Chemical Society.

Rivlin L.A.,Moscow State Institute of Radioengineering
Quantum Electronics | Year: 2012

Observation of photon behaviour in a waveguide model of spatial electromagnetic-field localisation establishes in a thought experiment a detailed analogy between the quantum-mechanical production of photon pairs at the horizon of an evaporating black hole and the classical nonlinear phenomenon of generation of subharmonics. © 2012 Kvantovaya Elektronika and Turpion Ltd.

Rivlin L.A.,Moscow State Institute of Radioengineering
Quantum Electronics | Year: 2012

We discuss the concept of remote inspection of the isotopic composition of objects in space by products of nuclear reactions (including the fission of heavy isotopes), initiated by directed accelerated beams of ultracold neutrons. Despite the partial unavailability of quantitative estimates of specific situations, the proposed approach is internally consistent. We emphasise the urgency of development the problem in question and offer directions for further research. © 2012 Kvantovaya Elektronika and Turpion Ltd.

Rivlin L.A.,Moscow State Institute of Radioengineering
Quantum Electronics | Year: 2012

We discuss the physical feasibility of association of particles noninteracting with each other, which arises in accordance with the uncertainty relation under the 'corporate' spatial confinement of the particle ensemble as a whole. Investigation is conducted by the example of an ensemble of ultracold neutrons placed in a common potential well of infinite depth. We present quantitative estimates and indicate the expected properties of the arising crystal- like spatially periodic structures. © 2012 Kvantovaya Elektronika and Turpion Ltd.

Rivlin L.A.,Moscow State Institute of Radioengineering
Quantum Electronics | Year: 2012

On the basis of the fundamental provision of general relativity about the equality of inertial and gravitational masses and the equivalence of kinematic and gravitational acceleration, a negative answer is given to the question posed in the title. © 2012 Kvantovaya Elektronika and Turpion Ltd.

Bdikin I.,University of Aveiro | Bystrov V.,University of Aveiro | Bystrov V.,Russian Academy of Sciences | Kopyl S.,University of Aveiro | And 6 more authors.
Applied Physics Letters | Year: 2012

Self-assembled peptide nanotubes (PNT) are unique nanoscale objects having a great potential for a multitude of applications. Strong piezoactivity and polar properties in aromatic dipeptides were recently observed in stand-alone nanotubes using piezoresponse force microscopy and 2 nd harmonic generation. In this work, we report macroscopic dielectric and polarization vs. field measurements on pressed PNTs before and after annealing at 150 °C. The results corroborate nanoscale study and present a clear evidence of ferroelectric-like behaviour and phase transition in this technologically important material. The dielectric constant of PNT pellets obeys apparent Curie-Weiss (CW) law with the CW constant C ≈ 230 C and transition temperature at T ≈ 142 C. © 2012 American Institute of Physics.

Rosenman G.,Tel Aviv University | Beker P.,Tel Aviv University | Koren I.,Tel Aviv University | Yevnin M.,Tel Aviv University | And 3 more authors.
Journal of Peptide Science | Year: 2011

Synthetic peptide monomers can self-assemble into PNM such as nanotubes, nanospheres, hydrogels, etc. which represent a novel class of nanomaterials. Molecular recognition processes lead to the formation of supramolecular PNM ensembles containing crystalline building blocks. Such low-dimensional highly ordered regions create a new physical situation and provide unique physical properties based on electron-hole QC phenomena. In the case of asymmetrical crystalline structure, basic physical phenomena such as linear electro-optic, piezoelectric, and nonlinear optical effects, described by tensors of the odd rank, should be explored. Some of the PNM crystalline structures permit the existence of spontaneous electrical polarization and observation of ferroelectricity. The PNM crystalline arrangement creates highly porous nanotubes when various residues are packed into structural network with specific wettability and electrochemical properties.We report in this review on a wide research of PNM intrinsic physical properties, their electronic and optical properties related to QC effect, unique SHG, piezoelectricity and ferroelectric spontaneous polarization observed in PNT due to their asymmetric structure. We also describe PNM wettability phenomenon based on their nanoporous structure and its influence on electrochemical properties in PNM.The new bottom-up large scale technology of PNT physical vapor deposition and patterning combined with found physical effects at nanoscale, developed by us, opens the avenue for emerging nanotechnology applications of PNM in novel fields of nanophotonics, nanopiezotronics and energy storage devices. Two sorts of vapor deposited diphenylalanine peptide nanotubes: Closed-end PNTs of nanobelt shape (a, b) contain cyclic-FF peptide molecules. They are composed from thin plates, do not demonstrate piezoelectric effect, SHG and strongly hydrophobic. Open-end hollow PNTs (c) contain linear FF molecules. They are composed from nanoballs, possess strong piezoelectric effect, SHG and hydrophilic properties. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.

Semin S.,Radboud University Nijmegen | Van Etteger A.,Radboud University Nijmegen | Cattaneo L.,Radboud University Nijmegen | Amdursky N.,Weizmann Institute of Science | And 6 more authors.
Small | Year: 2015

Self-assembly of bioinspired functional materials with ordered organization on the nano- and microscale is attracting a lot of interest due to its versatility, structural simplicity, cost efficiency, and biocompatibility. The optical properties of the FFMT's were probed by means of optical, confocal, and multiphoton microscopies combined with spectroscopy characterization. Moreover, morphology changes of the samples were confirmed by scanning electron microscopy (SEM). The possibility to control the position and spatial confinement of the thermally induced green luminescence from FFMT's through laser treatment is a reliable and simple way for a controlled optical response of peptide tubes and for a fundamental step towards future applications in photonic integrated circuits. The appearance of TPL/SPL have never been observed before in the visible spectral range for both hexagonal and orthorhombic crystal structures, since their optical activity have always been observed in the UV range.

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