The index of a binary word

Ili&#x107,, Aleksandar,Klavž,ar, Sandi,Rho, Yoomi Elsevier 2012 Theoretical computer science Vol.452 No.-

<P><B>Abstract</B></P><P>A binary word u is f-free if it does not contain f as a factor. A word f is d-good if for any f-free words u and v of length d, v can be obtained from u by complementing one by one the bits of u on which u and v differ, such that all intermediate words are f-free. We say that f is good if it is d-good for any d≥1. A word is bad if it is not good. The index β(f) of f is the smallest integer d such that f is not d-good, so that β(f)<∞ if and only if f is bad.</P><P>It is proved that β(f)<∣f<SUP>∣2</SUP> holds for any bad word f. In addition, β(f)<2∣f∣ holds for almost all bad words f and it is conjectured that the same holds for all bad words. We construct an infinite family of 2-isometric bad words. It is conjectured that the words of this family are all the words that are bad and 2-isometric among those with exactly two 1s. These conjectures are supported by computer experiments.</P>

Structural characterization of ultrafine-grained interstitial-free steel prepared by severe plastic deformation

&#x10c,í,ž,ek, J.,Jane&#x10d,ek, M.,Kraj&#x148,á,k, T.,Strá,ská,, J.,Hru&#x161,ka, P.,Gubicza, J.,Kim, H.S. Elsevier 2016 Acta materialia Vol.105 No.-

<P>Interstitial free steel with ultrafine-grained (UFG) structure was prepared by high-pressure torsion (HPT). The development of the microstructure as a function of the number of HPT turns was studied at the centre, half-radius and periphery of the HPT-processed disks by X-ray line profile analysis (XLPA), positron annihilation spectroscopy (PAS) and electron microscopy. The dislocation densities and the dislocation cell sizes determined by XLPA were found to be in good agreement with those obtained by PAS. The evolution of the dislocation density, the dislocation cell and grain sizes, the vacancy cluster size, as well as the high-angle grain boundary (HAGB) fraction was determined as a function of the equivalent strain. It was found that first the dislocation density saturated, then the dislocation cell size reached its minimum value and finally the grain size got saturated. For very high strains after the saturation of grain size the HAGB fraction further increased. The PAS investigations revealed that vacancies introduced by severe plastic deformation agglomerated into small clusters consisting of 9-14 vacancies. The evolution of the yield strength calculated from the microhardness as a function of strain was explained by the development of the defect structure. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.</P>

Strength enhancement of high entropy alloy HfNbTaTiZr by severe plastic deformation

&#x10c,í,ž,ek, J.,Hau&#x161,ild, P.,Cieslar, M.,Melikhova, O.,Vlasá,k, T.,Jane&#x10d,ek, M.,Krá,l, R.,Harcuba, P.,Luká,&#x10d,, F.,Zý,ka, J.,Má,lek, J.,Moon, J Elsevier 2018 Journal of alloys and compounds Vol.768 No.-

<P><B>Abstract</B></P> <P>Refractory metal high entropy alloy HfNbTaTiZr with ultrafine grained structure and grain size of ≈80 nm was processed by high pressure torsion. The development of microstructure, lattice defects and mechanical properties with increasing strain was examined. Grain refinement of HfNbTaTiZr alloy deformed up to the equivalent strain <I>e</I> ≈ 50 resulted in a significant enhancement of strength while keeping sufficient ductility. However, further straining <I>e</I> > 100 led to a decrease of strength and the loss of ductility due to the decomposition of solid solution facilitated by vacancies introduced by severe plastic deformation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High entropy alloy HfNbTaTiZr was nanostructured by high pressure torsion. </LI> <LI> Grain size of 80 nm was achieved by deformation to the equivalent strain e = 5. </LI> <LI> Structure refinement resulted in remarkable enhancement of strength of the alloy. </LI> <LI> Ductility remains sufficient for good workability. </LI> <LI> Further deformation to very high strains resulted in loss of strength. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Toward biomaterial-based implantable photonic devices

Humar, Matjaž,Kwok, Sheldon J. J.,Choi, Myunghwan,Yetisen, Ali K.,Cho, Sangyeon,Yun, Seok-Hyun De Gruyter Open 2017 Nanophotonics Vol.6 No.2

<P><B>Abstract</B></P><P>Optical technologies are essential for the rapid and efficient delivery of health care to patients. Efforts have begun to implement these technologies in miniature devices that are implantable in patients for continuous or chronic uses. In this review, we discuss guidelines for biomaterials suitable for use<I>in vivo</I>. Basic optical functions such as focusing, reflection, and diffraction have been realized with biopolymers. Biocompatible optical fibers can deliver sensing or therapeutic-inducing light into tissues and enable optical communications with implanted photonic devices. Wirelessly powered, light-emitting diodes (LEDs) and miniature lasers made of biocompatible materials may offer new approaches in optical sensing and therapy. Advances in biotechnologies, such as optogenetics, enable more sophisticated photonic devices with a high level of integration with neurological or physiological circuits. With further innovations and translational development, implantable photonic devices offer a pathway to improve health monitoring, diagnostics, and light-activated therapies.</P>

Expanding large global solutions of the equations of compressible fluid mechanics

Hadž,i&#x107,, Mahir,Jang, Juhi Springer-Verlag 2018 Inventiones mathematicae Vol.214 No.3

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni

Harmanec, P.,Holmgren, D. E.,Wolf, M.,Bož,i&#x107,, H.,Guinan, E. F.,Kang, Y. W.,Mayer, P.,McCook, G. P.,Nemravová,, J.,Yang, S.,&#x160,lechta, M.,Ruž,djak, D.,Sudar, D.,Svoboda, P. Springer-Verlag 2014 Astronomy and astrophysics Vol.563 No.-

Synthesis and Magnetic Properties of Hematite Particles in a “Nanomedusa” Morphology

Lee, Jin Bae,Kim, Hae Jin,Luž,nik, Janez,Jelen, Andreja,Paji&#x107,, Damir,Wencka, Magdalena,Jagli&#x10d,i&#x107,, Zvonko,Meden, Anton,Dolin&#x161,ek, Janez Hindawi Limited 2014 Journal of nanomaterials Vol.2014 No.-

<P>We present the synthesis, characterization, and magnetic properties of hematite particles in a peculiar “nanomedusa” morphology. The particles were prepared from an iron-silica complex by a hydrothermal process in a solution consisting of ethyl acetate and ethanol. The particles’ morphology, structure, and chemical composition were investigated by transmission electron microscopy, powder X-ray diffraction, and scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The “hairy” particles consist of a spherical-like core of about 100 nm diameter and fibrous exterior composed of thin “legs” of 5 nm diameter grown along one preferential direction. The particles’ cores are crystalline and undergo a magnetic phase transition to a weakly ferromagnetic state at a temperature of 930 K that matches reasonably the Néel temperature of bulk hematite. However, unlike bulk hematite that undergoes Morin transition to an antiferromagnetic state around room temperature and small hematite nanoparticles that are superparamagnetic, the “nanomedusa” particles remain weakly ferromagnetic down to the lowest investigated temperature of 2 K. Each particle thus represents a nanodimensional “hairy” ferromagnet in a very broad temperature interval, extending much above the room temperature. Such high-temperature ferromagnetic nanoparticles are not frequently found among the nanomaterials.</P>

A 21 cm SPECTRAL AND CONTINUUM STUDY OF IC 443 USING THE VERY LARGE ARRAY AND THE ARECIBO TELESCOPE

Lee, Jae-Joon,Koo, Bon-Chul,Yun, Min S.,Stanimirovi&#x107,, Snež,ana,Heiles, Carl,Heyer, Mark American Institute of Physics 2008 The Astronomical journal Vol.135 No.3

<P>We report 21 cm spectral-line and continuum observations of the Galactic supernova remnant IC 443 using the Very Large Array (VLA) and the Arecibo telescope. By combining the VLA and Arecibo data, both covering the full extent of IC 443, we have achieved an unprecedented combination of sensitivity and angular resolution, over the continuous range of angular scales from ~40'' to ~1°. Our new radio observations not only reveal previously unknown features of IC 443 but also show the details of the remnant more clearly. The radio morphology of IC 443 consists of two nearly concentric shells. Our 21 cm radio continuum data show that the two shells have distinctly different radial intensity distributions. This morphology supports the scenario whereby the western shell is a breakout portion of the remnant into a rarefied medium. We have developed a dynamical model accounting for the breakout, which provides an estimate for the remnant age of ~2 × 10<SUP>4</SUP> yr. The southeastern boundary of the remnant shows interesting features, seen in our observations for the first time: a faint radio continuum halo and numerous 'spurs.' These features are mainly found in the region where IC 443 overlaps with another remnant, G189.6+3.3. These features most likely originate from the interactions of IC 443 with the surrounding medium. The H <SPAN CLASS='sml'>I</SPAN> emission associated with IC 443 appears over the velocity range between −100 km s<SUP>−1</SUP> and 50 km s<SUP>−1</SUP>. The strongest absorption is seen around v<SUB>LSR</SUB> ~ −5 km s<SUP>−1</SUP>, which corresponds to the systemic velocity of IC 443. We identify a broad, extended lane of H <SPAN CLASS='sml'>I</SPAN> gas near the systemic velocity as preshock gas in the southern part of the remnant. Most of the shocked H <SPAN CLASS='sml'>I</SPAN> gas is located along the southern supernova remnant (SNR) boundary and is blueshifted. We derive an accurate mass of the shocked H <SPAN CLASS='sml'>I</SPAN> gas using template HCO<SUP>+</SUP> (1-0) spectra, which is 493 ± 56 M<SUB>☉</SUB>. Our high-resolution H <SPAN CLASS='sml'>I</SPAN> data enable us to resolve the shocked H <SPAN CLASS='sml'>I</SPAN> in the northeastern region into a few filamentary structures, which are well correlated with radiative filaments, in both position and velocity. This represents the first unambiguous detection of the recombined H <SPAN CLASS='sml'>I</SPAN> in an atomic shock. The characteristics of the filaments are not consistent with a clumpy shock model where the radiative signature is from dense clumps. Instead we propose that the shock has been propagating through a uniform medium of n<SUB>H</SUB> ~ 10 cm<SUP>−3</SUP>.</P>

Ethynylene-analogues of hemicurcuminoids: Synthesis and ground- and excited properties of their boron difluoride complexes

&#x160,tefane, Bogdan,Pož,gan, Franc,Kim, Eunsun,Choi, Eunyoung,Ribierre, Jean-Charles,Wu, Jeong Weon,Ponce-Vargas, Miguel,Le Guennic, Boris,Jacquemin, Denis,Canard, Gabriel,Zaborova, Elena,Fages Applied Science Publishers 2017 Dyes and pigments Vol.141 No.-

<P><B>Abstract</B></P> <P>The synthesis, characterization and (TD)-DFT calculations of the electrochemical and photophysical properties of novel ethynylene-analogues of hemicurcuminoids are described. These dyes are both emissive in solution and in the solid state. While compounds that emit through an efficient charge transfer (CT) state show solvatochromic behaviour associated with low fluorescence quantum yields, those lacking of donor groups show high fluorescence quantum yields of 70–80%, in solution. The latter dyes also present the advantage to emit in the solid state in the visible region with fluorescence quantum yields up to 23%. Their condensed phase spectrum can be bathochromically shifted to the near infrared region (742 nm) by appending a strong donor group.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Synthesis of new fluorophores based on hemicurcuminoid boron difluoride. </LI> <LI> Photophysical study reveals strong emission of the dyes not containing charge transfer states. </LI> <LI> Fluorescence properties of dyes in their condensed phase show aggregation induced emission. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Nonlinear localized flat-band modes with spin-orbit coupling

Gligori&#x107,, G.,Maluckov, A.,Hadž,ievski, Lj.,Flach, Sergej,Malomed, Boris A. American Physical Society 2016 Physical Review B Vol.94 No.14

<P>We report the coexistence and properties of stable compact localized states (CLSs) and discrete solitons (DSs) for nonlinear spinor waves on a flat-band network with spin-orbit coupling (SOC). The system can be implemented by means of a binary Bose-Einstein condensate loaded in the corresponding optical lattice. In the linear limit, the SOC opens a minigap between flat and dispersive bands in the system's band-gap structure, and preserves the existence of CLSs at the flat-band frequency, simultaneously lowering their symmetry. Adding on-site cubic nonlinearity, the CLSs persist and remain available in an exact analytical form, with frequencies that are smoothly tuned into the minigap. Inside of the minigap, the CLS and DS families are stable in narrow areas adjacent to the FB. Deep inside the semi-infinite gap, both the CLSs and DSs are stable too.</P>