bluuebunny/crossref_metadata_2025 huggingface dataset:
Algorithmic unconscious: why psychoanalysis helps in understanding AI
Authors: Possati Luca M.
Published: April 2020

The central hypothesis of this paper is that the concepts and methods of psychoanalysis can be applied to the study of AI and human/AI interaction. The paper connects three research fields: machine behavior approach, psychoanalysis and anthropology of science. In the “Machine behavior: research perspectives” section, I argue that the behavior of AI systems cannot be studied only in a logical-mathematical or engineering perspective. We need to study AI systems not merely as engineering artifacts, but as a class of social actors with particular behavioral patterns and ecology. Hence, AI behavior cannot be fully understood without human and social sciences. In the “Why an unconscious for AI? What this paper is about” section, I give some clarifications about the aims of the paper. In the “Unconscious and technology. Lacan and Latour” section, I introduce the central thesis. I propose a re-interpretation of Lacan’s psychoanalysis through Latour’s anthropology of sciences. The aim of this re-interpretation is to show that the concept of unconscious is not so far from technique and technology. In the “The difficulty of being an AI” section, I argue that AI is a new stage in the human identification process, namely, a new development of the unconscious identification. After the imaginary and symbolic registers, AI is the third register of identification. Therefore, AI extends the movement that is at work in the Lacanian interpretation of the mirror stage and Oedipus complex and which Latour’s reading helps us to clarify. From this point of view, I describe an AI system as a set of three contrasting forces: the human desire for identification, logic and machinery. In the “Miscomputation and information” section, I show how this interpretative model improves our understanding of AI.
Camera-based sample-position detection and control for microgravity electrostatic levitation
Authors: Bräuer D. , Neumann C.
Published: April 2020

This paper presents a method for high-speed sample detection and position control in an electrostatic levitator. The algorithm uses images acquired from two charge coupled device cameras and allows for robust and reliable detection of the sample position under various process conditions. The results show improvements over position sensitive detector systems especially under harsh environments and during autonomous operation under microgravity conditions. The position of samples with a radius from 0.6 mm to 1.1 mm is detected in three dimensions with an accuracy of ±40 μm inside a 7 mm × 7 mm × 7 mm levitation area. The two orthogonally arranged cameras, recording images at a resolution of 260 px × 260 px, are used to calculate the position every 5 ms. The control model and the corresponding position controller for the three axes are presented as well. The system was successfully tested in the laboratory and under microgravity conditions at the drop tower, during parabolic flights, and on the MAPHEUS sounding rocket.
Parallel magnetic particle imaging
Authors: Vogel Patrick , Kampf Thomas , Herz Stefan , Rückert Martin A. , Bley Thorsten A. , Behr Volker C.
Published: April 2020

Magnetic Particle Imaging (MPI) is a promising tomographic method to visualize the distribution of superparamagnetic materials in three-dimensions. For encoding, a strong gradient represented by a field free point (FFP) or a field free line (FFL) is steered rapidly through the field of view (FOV), acquiring the signal successively. Conventional MPI scanners only provide a single FFP or FFL to sample the entire scan volume, which limits the size of the FOV and/or the temporal resolution. The alternative scanner concept of Traveling Wave MPI (TWMPI) uses a dynamic linear gradient array (dLGA) for dynamic FFP generation along the symmetry axis. The TWMPI scanner is capable of creating multiple FFPs simultaneously, and usually care is taken to locate only a single FFP in the desired FOV. In this manuscript, the concept of parallel MPI utilizing multiple FFPs simultaneously is introduced. For that, conceptual simulations are presented followed by reconstruction approaches for visualization of parallel MPI signals. In addition, an initial parallel MPI experiment with simultaneous acquisition of signals from two FFPs inside the FOV of the same scanner using two receive chains is demonstrated. This allows scanning a doubled FOV within the same acquisition time without sacrificing resolution compared to the standard TWMPI scanner.
Kinematic parameter optimization of a flapping ellipsoid wing based on the data-informed self-adaptive quasi-steady model
Authors: Zheng Hongyu , Xie Fangfang , Ji Tingwei , Zheng Yao
Published: April 2020

This paper constructs an optimization framework based on the data-informed self-adaptive quasi-steady model. The framework aims at achieving a specific aerodynamic force coefficient by optimizing the kinematic parameters of the flapping motion of an ellipsoid wing. All the model coefficients of this quasi-steady model are calibrated empirically by the data-informed training. At each optimization iteration, the data-informed training is implemented by the local ridge regression, where the initial training samples are extracted from simulation examples, and the weight coefficients are calculated by the compactly supported radial basis function with the previous optimal solution as the center point. Furthermore, a numerical simulation is conducted to evaluate the accurate aerodynamic force coefficient corresponding to the current optimal solution. The relative error between the accurate simulation result and optimization objective is calculated as the convergence criteria of the optimization. Then, the effects of the kinematic parameters on the time-averaged lift coefficient are first investigated, which indicate that the in-phase flapping with high flapping angle amplitude and medium geometric angle of attack amplitude is beneficial to the lift coefficient. Moreover, the kinematic optimization is conducted for a three-dimensional flapping ellipsoid wing in the hovering mode. The results demonstrate that the leading-edge vortex is crucial for the force generation. Moreover, in one flapping period, the asymmetrical wake and two unequal lift coefficient peaks emerge under the figure-O motion pattern while the vortex structures are highly symmetrical under the figure-8 motion pattern.
Microwave devices based on superconducting surface electromagnetic wave resonator (Review article)
Authors: Malyshev V. , Melkov G. , Prokopenko O.
Published: April 2020

In this paper we present an overview of the microwave properties of a surface electromagnetic wave resonator (SEWR) made on the basis of a superconducting film, and also consider possible applications of such resonators to create various microwave devices. Features of such a SEWR are the simplicity of its design (such a resonator, in fact, can be just the superconducting film itself on a dielectric substrate); a large amplitude of microwave electromagnetic field on the surface of the resonator’s superconducting film, which allows one to organize intense interaction of this field with the superconductor; the possibility of synchronous operation of integrated superconducting elements, embedded in the resonator, under the action of its microwave field. The review is based on our works published since 2000 and discusses the possible applications of superconducting SEWRs to create a new class of microwave filters, microwave signal generators and detectors, and other devices based on Josephson junctions.
Critical phenomenon of vortex motion in superconductors: Vortex instability and flux pinning
Authors: Leo A. , Nigro A. , Grimaldi G.
Published: April 2020

We have studied vortex dynamics in superconducting materials at very high vortex velocities as a function of the applied magnetic field. High velocity vortex dynamics can become critical, so that an instability occurs, leading the system to quench abruptly to the normal state. The presence of pinning mechanisms in all superconductors not only is able to foster high critical currents but it can strongly influence vortex flow, thus determining a different behavior of the critical vortex velocity v*. The magnetic field dependence of v* is extremely sensitive to the type of material pinning, and this is crucial for an applicative point of view, since vortex motion approaching v* means a dissipative flux flow state which will probably end with a flux flow instability. If it is possible to predict these critical parameters, than it will be easier to control those critical phenomena. Although a fully theoretical model of flux flow instability in the presence of pinning is still lacking, a phenomenological approach has been recently proposed for the hot-electron vortex flow instability. Here we present a successful example of perfect correspondence between experiment and theoretical approach in the case of Mo3Ge thin films with and without geometrical pinning barriers.
Ultrathin superconducting NbRe microstrips with hysteretic voltage-current characteristic
Authors: Cirillo C. , Caputo M. , Parlato L. , Ejrnaes M. , Salvoni D. , Cristiano R. , Pepe G. P. , Attanasio C.
Published: April 2020

Ultrathin microstrips based on polycrystalline NbRe films were investigated in order to preliminarily test the suitability of this material for the realization of superconducting single-photon detectors. The voltage-current characteristics measured on these samples show clear hysteresis. This is a fundamental ingredient for investigating single-photon detection as well as single vortex fluctuation phenomena in 2D NbRe-based devices.
Electron-electron and electron-phonon relaxation in metals excited by optical pulse
Authors: Kabanov V. V.
Published: April 2020

A short overview of theoretical models for the description of the relaxation processes in metals excited by a short laser pulse is presented. The main effort is given to description of different processes which are taking place after absorption of the laser pulse. Widely used two-temperature model is discussed and the conditions of applicability of this model are identified. Various approaches for solving the Boltzmann kinetic equations are discussed. It is identified that in the case of low excitation limit the relaxation is determined by the emission of phonons by photoexcited electrons. The possibility to obtain the value of the electron phonon coupling constant from experiments is discussed.
Transport and magnetic properties of a superconducting closed loop containing a thin-film quantum interferometer
Authors: Bondarenko S. I. , Koverya V. P. , Krevsun A. V.
Published: April 2020

The current in a superconducting closed loop containing a thin-film interferometer with two point contacts (two Josephson-type weak links) has been measured as a function of the transport current and external magnetic field applied to interferometer. The differences between the transport and magnetic dependences of the system under study and similar characteristics for a superconducting closed loop containing an interferometer in the form of a single pressed point contact are discussed.
Stochastic approach optimizes a system’s wavefunction to improve computational efficiency
Authors: Bandari Anashe
Published: April 2020

By breaking apart a large computation into smaller components, researchers can solve the Schrodinger equation for complicated systems.
Plasmonic nano-dumbbells for enhanced photothermal and photodynamic synergistic damage of cancer cells
Authors: Yin Jinchang , Wu Haonan , Wang Xiang , Tian Li , Yang Renlong , Liu Lizhi , Shao Yuanzhi
Published: April 2020

The longitudinal surface plasmon resonance of light-irradiated gold nanorods (Au NRs) is generated to enhance the local electric fields of Au NR-based nano-dumbbells (NDs), tailored specifically by coating mesoporous silica at two poles of Au NRs and embedding photosensitizer indocyanine green (ICG) into the mesopores. The assembled NDs possess a superior uniformity and water dispersity with a strong plasmonic absorption around 800 nm. Time-domain finite-difference calculations indicate that the enhanced local electric field of NDs is predominantly distributed in the dumbbells at two poles of Au NRs, which improves the photonic performance of ICG significantly. Illuminated by an 800 nm laser, the fabricated NDs demonstrate an enhanced combination of photothermal and photodynamic effects in comparison to either Au NRs or ICG alone. Synergistic damaging of photothermal and photodynamic combination to nasopharyngeal carcinoma cells has been corroborated experimentally, thus causing substantial cell death under a lower incident near-infrared laser power. This study concludes that the plasmonic NDs combined synergistically with efficient photothermal and photodynamic effects are highly promising in cancer therapy.
A comparative study of spin Hall magnetoresistance in Fe2O3-based systems
Authors: Zhou Y. J. , Chen X. Z. , Zhou X. F. , Bai H. , Chen R. Y. , Pan F. , Song C.
Published: April 2020

Spin Hall magnetoresistance (SMR) provides a unique opportunity for the signal readout of magnetic ordering, especially for magnetic insulators. However, the magnitude of SMR signals is quite small, generally lower than one in a thousand, which is a persistent challenge in the field of spintronics. Here, we investigate SMR at room temperature in α-Fe2O3/Pt and γ-Fe2O3/Pt bilayers as well as the α-Fe2O3/Pt/γ-Fe2O3 trilayer, where α-Fe2O3 and γ-Fe2O3 are antiferromagnetic and ferrimagnetic materials, respectively. In contrast to the positive SMR in the γ-Fe2O3/Pt bilayer, an unprecedentedly large negative SMR with the magnitude of ∼0.35% is observed in the α-Fe2O3/Pt bilayer due to the spin-flop. The α-Fe2O3/Pt/γ-Fe2O3 trilayer shows features of a combination of positive and negative SMR. A comparative study of SMR in the Fe2O3 family not only enriches spin physics, but also makes Fe2O3 a versatile candidate in spintronic devices.
Cryogenic behavior of NbO2 based threshold switching devices as oscillation neurons
Authors: Wang Panni , Khan Asif I. , Yu Shimeng
Published: April 2020

This Letter investigates the cryogenic behavior of NbO2 threshold switching devices. Pt/NbO2/Pt devices are demonstrated to be well functional as threshold switching devices at ultra-low temperature (4 K). When the temperature decreases, the OFF-state resistance of NbO2 increases and the switching voltage increases. With the extracted characteristics of NbO2 ranging from 4 K to 300 K, we continue to study the neuromorphic system using the crossbar array with resistive memories as resistive synapses and NbO2 as oscillation neurons at different temperatures through SPICE simulation. The simulation results show that the oscillation systems could still work properly at 4 K. The oscillation amplitude decreases as temperature increases. The oscillation frequency depends on both the temperature and the input voltage.
Crystal growth rates and liquid dynamics at the crossover between stable crystal phases
Authors: Sun Gang , Harrowell Peter
Published: April 2020

The crystal growth rates from a binary A50B50 Lennard-Jones liquid are calculated as a function of the variation of the interspecies interaction length σAB. At the crossover in stability between the CsCl and NaCl crystal phase, the growth rate slows down and exhibits a maximum in the activation energy for atomic attachment to the growing crystal. Using assignment theory to determine the size of the transformation displacement, we show that these trends can be explained in terms of the changes in the cage size of the liquid.
Numerical solution of the dynamical mean field theory of infinite-dimensional equilibrium liquids
Authors: Manacorda Alessandro , Schehr Grégory , Zamponi Francesco
Published: April 2020

We present a numerical solution of the dynamical mean field theory of infinite-dimensional equilibrium liquids established by Maimbourg et al. [Phys. Rev. Lett. 116, 015902 (2016)]. For soft sphere interactions, we obtain the numerical solution by an iterative algorithm and a straightforward discretization of time. We also discuss the case of hard spheres for which we first derive analytically the dynamical mean field theory as a non-trivial limit of that of soft spheres. We present numerical results for the memory function and the mean square displacement. Our results reproduce and extend kinetic theory in the dilute or short-time limit, while they also describe dynamical arrest toward the glass phase in the dense strongly interacting regime.
On the critical exponent “instantaneous blow-up” versus “local solubility” in the Cauchy problem for a model equation of Sobolev type
Authors: Korpusov M. O. , Panin A. A. , Shishkov A. E.
Published: April 2020

We consider the Cauchy problem for a model partial differential equation of order three with a non-linearity of the form

. We prove that when

the Cauchy problem in

has no local-in-time weak solution for a large class of initial functions, while when

there is a local weak solution.
On critical exponents for weak solutions of the Cauchy problem for a non-linear equation of composite type
Authors: Korpusov M. O. , Matveeva A. K.
Published: April 2020

We consider the Cauchy problem for a model partial differential equation of third order with non-linearity of the form

, where

for

and

. We construct a fundamental solution for the linear part of the equation and use it to obtain analogues of Green’s third formula for elliptic operators, first in a bounded domain and then in unbounded domains. We derive an integral equation for classical solutions of the Cauchy problem. A separate study of this equation yields that it has a unique inextensible-in-time solution in weighted spaces of bounded and continuous functions. We prove that every solution of the integral equation is a local-in-time weak solution of the Cauchy problem provided that

. When

, we use Pokhozhaev’s non-linear capacity method to show that the Cauchy problem has no local-in-time weak solutions for a large class of initial functions. When

, this method enables us to prove that the Cauchy problem has no global-in-time weak solutions for a large class of initial functions.
Phylogeny and divergence estimates for the gasteruptiid wasps (Hymenoptera : Evanioidea) reveals a correlation with hosts
Authors: Parslow Ben A. , Jennings John T. , Schwarz Michael P. , Stevens Mark I.
Published: April 2020

The Gasteruptiidae are an easily recognised family of wasps whose larvae are considered predator-inquilines in the nests of solitary bees and wasps. There has been minimal molecular research on the family and as a result little understanding of the evolutionary relationships within the group. We present the first molecular phylogeny focused on Gasteruptiidae, generated using three molecular fragments (mitochondrial C01 and nuclear markers EF1-α and 28s) and estimate the divergence times of Evanioidea based on three secondary calibration points. The analyses included 142 specimens of Gasteruptiidae and 5 outgroup taxa from Aulacidae and Evaniidae. The monophyly of the Gasteruptiidae and its subfamilies Gasteruptiinae (Gasteruption) and Hyptiogastrinae (Hyptiogaster and Pseudofoenus) are confirmed. Our results indicate that Evanioidea diverged during the late Jurassic at 151.3 (171.99–136.15)Ma with Evaniidae during the early Cretaceous at 137.33 (140.86–133.67)Ma, and Gasteruptiidae during the Palaeocene at 60.23 (83.78–40.02)Ma. The crown age of Hyptiogastrinae was estimated to be during the mid-Eocene 40.72 (60.9–22.57)Ma and for Gasteruption during the early Eocene at 47.46 (64.7–31.75)Ma, which corresponded to their host divergence ages. We anticipate that more extensive taxon sampling combined with the use of phylogenomic data will help resolve low support within the Gasteruption clade.
Incorporating an advance care planning screening tool into routine health assessments with older people
Authors: Franklin Abigail E. , Rhee Joel , Raymond Bronwyn , Clayton Josephine M.
Published: April 2020

General practice is arguably the ideal setting to initiate advance care planning (ACP), but there are many barriers. This pilot study was designed to assess the feasibility, acceptability and perceived utility of a nurse-facilitated screening interview to initiate ACP with older patients in general practice. Patients were recruited from four general practices in Sydney, Australia. General practice nurses administered the ACP screening interview during routine health assessments. Patients and nurses completed a follow-up questionnaire consisting of questions with Likert responses, as well as open-ended questions. Descriptive statistics and content analysis were used to analyse the data. Twenty-four patients participated; 17 completed the follow-up questionnaire. All patients found the ACP screening interview useful and most felt it would encourage them to discuss their wishes further with their family and general practitioner. Several patients were prompted to consider legally appointing their preferred substitute decision-maker. All six participating nurses found the screening interview tool useful for initiating discussions about ACP and substitute decision-making. This nurse facilitated screening tool provides a simple, acceptable and feasible approach to introducing ACP to older general practice patients during routine health assessments.
Thermo- and physicochemical properties of native and exotic forest species of Valparaíso, Chile, as essential information for fire risk management
Authors: Guerrero Fabián , Toledo Mario , Ripoll Nicolás , Espinoza Lorena , Morales Rodrigo , Muñoz Ariel , Taborga Lautaro , Carrasco Yulian
Published: April 2020

Wildfires in the Valparaíso region (Chile) account for one of the main threats to local biodiversity, ecosystem services and infrastructure. This study focused on producing an initial record of thermo- and physicochemical properties of local forest species. For this purpose, leaf samples of species found in the Peñuelas Lake National Reserve, namely Pinus radiata, Eucalyptus globulus, Acacia dealbata, Quillaja saponaria and Cryptocarya alba, were collected and analysed. Higher and lower heating value, flash point, density and moisture content tests were performed for each sample. Overall results showed that lower heating values measured for both native and exotic species could indicate a high energy release source in wildfires. However, differences in the flash point between species indicated that C. alba and E. globulus had a lower ignition resistance than other species tested, possibly due to a lower flash point. In contrast, Q. saponaria and A. dealbata had the highest flash point for native and exotic species respectively. Finally, all presented data and procedures were aimed at establishing a foundation for a national database of critical forest species properties to be used in wildfire simulation tools. This database will enhance forest fire management effectiveness in Chile.
A fluorescence method to visualize the nuclear boundary by the lipophilic dye DiI
Authors: Miyazaki Kohei , Yano Ken-Ichi , Saitoh Hisato
Published: April 2020

Here, we describe a procedure to fluorescently contrast the nuclear boundary using the lipophilic carbocyanine dye DiI in cultured human cells. Our procedure is simple and is applicable to detect nuclear boundary defects, which may be relevant to studies on nuclear envelope dynamics, micronuclei formation and cancer biology.

Abbreviations

DiI: 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate; DiO: 3,3ʹ-dioctadecyloxacarbocyanine perchlorate; NE: nuclear envelope; RanBP2: Ran-binding protein 2/Nucleoporin 358
Photodegradation of surface passivated GaAs nanowires
Authors: Alekseev P A , Smirnov A N , Davydov V Yu , Haggrén T , Lipsanen H , Dunaevskiy M S , Berkovits V L
Published: April 2020

Efficiency of in situ AlGaAs and GaP and ex situ nitride surface passivation of p+ GaAs nanowires was studied. The efficiency was estimated by comparing of the photoluminescence intensity of the passivated nanowires with the unpassivated nanowire. The AlGaAs and nitride passivation lead to the increasing of the PL intensity by three orders of magnitude while the GaP passivation increases PL intensity only by one order. Photodegradation of the passivated NWs under intensive laser illumination was observed. AlGaAs, GaP and nitride passivated NWs photodegrade after one-minute exposure under laser power densities of 500, 300 and 30 kW/cm2, respectively.
Acoustic Phonons in Periodical GeSiSn/Si Nanostructures
Authors: Anikin K.V. , Timofeev V.A. , Solonenko D. , Nikiforov A.I. , Milekhin A.G. , Zahn D. R.T.
Published: April 2020

We apply Raman spectroscopy to study the phonon spectrum in periodical GeSiSn/Si nanostructures with Sn concentration varied from 0 to 20%. In the optical spectral region, an insignificant shift of the phonon mode positions with a variation of the Sn content prevents determination of Sn concentration relying only on the optical phonons behavior. In the acoustic region, we observe the doublets of the folded acoustic phonons, the spectral positions of which undergo the low-frequency shift with increasing the Sn content. The application of the elastic continuum model with the linear approximation of sound velocity via Sn content in GeSiSn layers fails to explain the experimental results. This indicates a nonlinear Sn concentration dependence of sound velocity in GeSiSn layers which describes well the positions of the folded acoustic phonons.
Optimal microwave heating of biochar containing iron ore pellets
Authors: Anzulevich Anton P , Kalganov Dmitrii A , Anzulevich Svetlana N , Bychkov Igor V , Peng Zhiwei
Published: April 2020

Process of microwave heating of a composite material consisting of a mixture of iron oxides (Fe2O3 / Fe3O4), a binder (bentonit), and a carbon-containing powder (biochar) was studied theoretically and experimentally. The values of complex permittivity and permeability of the samples under study were found according to effective medium approximation and enhanced Bruggeman expression in particular. Spatial distribution of temperature in the pellet of composite material was obtained when heated by an electromagnetic field with a frequency of 2.45 GHz, as well as the time dependencies of sample surface temperature.
Influence of heteroatoms on optical properties and photoluminescence kinetics of carbon dots
Authors: Arefina I A , Khavlyuk P D , Stepanidenko E A , Dubavik A , Cherevkov S A , Baranov A V , Fedorov A V , Ushakova E V , Rogach A L
Published: April 2020

Carbon dots have attracted much attention due to the ease of synthetic methods and their stable photoluminescence with relatively high quantum yield. By the doping of carbon dot by heteroatoms the optical transitions can be tuned in a wide spectral range. In this work, the impact of heteroatoms on the optical properties of carbon dots has been investigated: the appearance of the luminescent states attributed to the CD surface states and the dependence of the photoluminescence lifetime versus emission wavelength have been revealed.
Optical modes in perovskite nanowire with shallow bi-periodic grating
Authors: Berestennikov A , Gorlach M , Makarov S , Khanikaev A
Published: April 2020

In this work, we investigate electromagnetic modes supported by a perovskite CsPbBr3 nanowire with a shallow periodic grating on top. By creating a domain-wall geometry, we introduce a topological defect into the nanowire and observe a defect-localized lasing state. By tuning the parameters of the structure we ensure that the frequency of the localized state fits the frequency of exciton resonance in perovskite and perform full-wave numerical simulations of the field distribution for such state.
Bottom-up nano-integration route for modified carbon nanotube spintronic device fabrication
Authors: Mosse I S , de Sousa A S , Ncube S , Coleman C , Bhattacharyya S , Irzhak A , Gratowski S , Koledov V
Published: April 2020

This study is focused on a bottom-up nano-integration route for the production of carbon based spintronic devices. In order to enhance magnetic interactions along nanotube walls a controlled synthetic chemical technique is utilized, this method is based on a two-step method which firstly looks at the functionalization of nanotubes (carbonyl groups) and subsequently the attachment of an organo-metallic complex to the carbonyl group. The system is then characterized in bulk, including magnetometry analysis as well as transport at low temperatures. Mesoscopic electron-spin correlations have been observed as well as a clear crossover from superparamagnetism to weakly ferromagnetic depending on the functionalization technique. We then demonstrate a novel fabrication technique based on nano-integration utilizing a nano-tweezer created from a memory metal alloy. The devices envisioned include quantum rings, crossed junction as well as fine network structures that can be manipulated using nano-probes. As the carbon nanotubes have been functionalized with nanoscale magnetic molecules, such devices are interesting for novel spintronic applications.
Application of laser radiation for creation of metamaterial based on rapidly quenched shape memory TiNiCu alloy
Authors: Borodako K A , Shelyakov A V , Sitnikov N N , Irzhak A V , Tabachkova N Yu , Ivanov A A , Koledov V V
Published: April 2020

The work deals with application of laser radiation for creation of metamaterial – layered structural composite based on rapidly quenched TiNiCu thin ribbon. Structural properties of the composite were examined by transmission and scanning electron microscopy. Considerable two-way shape memory effect was achieved and studied.
Nontrivial invisibility induced by optical hybrid anapole
Authors: Canós Valero A. , Gurvitz E. , Miroshnichenko A.E. , Shalin A.S.
Published: April 2020

The novel hybrid anapole states supported by dielectric nanoparticles are associated with the condition whem all the dominant Cartesian multipoles interfere destructively with their corresponding toroidal counterparts. They are characterized by a negligible light scattering for any observation direction. In the current work, we have proven the existence of high order hybrid anapole states in the visible range, resulting in a drastic reduction of the scattered radiation from a cylindrical nanoparticle with dimensions comparable to the wavelength. We demonstrate it by expanding the numerically calculated scattering cross section of the nanoparticle in terms of the Cartesian multipole decomposition. The simulations illustrate the simultaneous resonant suppression of the four leading multipole contributions to radiation (e.g. electric and magnetic dipoles and quadrupoles). Our results confirm the possibility to observe the effect experimentally, paving the way for future applications in dielectric nanophotonics.
A Transient Grating Method to Measure the Dispersion of Elastic Waves in Nanostructures
Authors: Charron E. , Lu L. , Bonello B. , Boyko O. , Glushkov E. , Glushkova N. , Tchernycheva M. , Gogneau N.
Published: April 2020

We describe the so-called “Transient Grating Method” which is a non-invasive experimental technique well suited to measure the dispersion properties of ordered or disordered nanostructures and thin films, at frequencies up to a few GHz. This pump-and-probe technique involves the interference pattern produced by two in-coming IR optical pulses to set a standing elastic wave on the surface of the sample through photoelastic processes. The wave vector of this elastic wave can be easily tuned by adjusting the angle between the two incident beams. Two continuous visible laser beams in a heterodyne detection scheme are used to detect the vibrations on the surface and in turn the dispersion of the related elastic modes. The achievements of the technique are illustrated by the measurement of the dispersion of surface acoustic waves in piezogenerators consisting of GaN nanowires embedded into a dielectric matrix (HSQ). We then report on the analysis of the experimental data that allowed extracting the elastic parameters of this composite medium.
Nano-manipulation and laser treatment as alternative routes for strain engineering in Graphene
Authors: Coleman C , Erasmus R , Mtsuko D , Gratowski S von , Koledov V , Bhattacharyya S
Published: April 2020

In this work we present two alternative routes for strain engineering in graphene. The first technique involves a laser treatment a low power that was found to create micro-bubbles on single layer graphene flakes. The effect of strain and doping of the graphene along these micro-bubbles is mapped and analysed using Raman Spectroscopy and it is found that a pronounced split in the G-band phonon mode can be attributed to large strain induction. The second technique discussed involves the use of nano-manipulating probes to manoeuvre and deform multilayer graphene flakes. Devices fabricated from such deformed flakes exhibit transport deviating from the expected 2D/quasi-2D electron gas observed in single layer graphene and graphite. We observe signatures of quantum linear magnetoresistance up to large fields in such devices.
Continuous Heating Microwave System Based on Mie Resonances
Authors: Jacobsen R E , Arslanagić S , Lavrinenko A V
Published: April 2020

Nowadays microwave heating is a part of many people’s daily life, whereas industrial microwave heating is not as widespread. The permittivity of many liquids is highly temperature dependent, which makes it difficult to control the heating process when using microwaves. Presently, we propose two continuous heating microwave systems for heating, pasteurization and sterilization of liquids. Both designs utilize resonances in cylindrical water-filled cavities of different sizes so that high absorption through the whole heating process is achieved. The proposed systems can heat water from 0 to 100 °C, and their effectiveness is significantly higher than that of a single water cavity.
Excitonic nature of dispersion of two-dimensional transition metal dichalcogenides and effect of annealing on excitons
Authors: Ermolaev G. A. , Komissar D. A. , Krivova G. M. , Tatarkin D. E. , Voronin K. V. , Yakubovsky D. I. , Stebunov Y. V. , Arsenin A. V. , Novikov S. M. , Volkov V. S.
Published: April 2020

In present study, we develop an effective and universal technique for retrieving dispersion of bulk and monolayer TMDs from spectroscopic ellipsometry measurements. The basis of the method is excitonic nature of the dispersion. In addition, we demonstrate beneficial influence of annealing on optical properties of MoS2.
Polymer capsules modified with iron oxide nanoparticles as an effective platform for MRI visualization and drug delivery
Authors: Fatkhutdinova L I , Andreychenko A , Brui E , Timin A S , Pavlovskaya G E , Khlobystov A N , Zyuzin M V
Published: April 2020

Efficiency of existing (usually toxic) drugs can be increased substantially with the targeted effect on the site of the disease. A potential platform for the targeted drug delivery can be polymer capsules. This will help reduce side effects on the human body and start treatment at the early stages of the disease. Modification of such capsules with the magnetic nanoparticles allows their visualization using magnetic resonance imaging (MRI). In this study the use of polymer microcapsules modified with iron oxide nanoparticles are employed as contrast agents for T2-weighted magnetic resonance (MR) images, the possibility of their implementation as for drug delivery carriers are discussed. For this, two different types of polymer capsules are synthesized. The results on the spin-spin and spin-lattice relaxivities were obtained.
Scattering-matrix analysis of nanoparticle lattices in dipole approximation
Authors: Fradkin I M , Dyakov S A , Gippius N A
Published: April 2020

Fourier modal method (FMM) proved itself as an effective technique for investigation of layered periodic structures. However, it fails to deal with arrays of small particles because of high gradients in a local field. In this paper, we demonstrate the capability of the method, which is based on the construction of scattering matrices of arrays of resonant nanoparticles semianalytically in discrete dipole approximation (DDA). This approach is much faster than conventional ones and therefore provides an opportunity for thorough consideration of various layered structures with small periodic inclusions in terms of the RCWA. The performance of the considered method is demonstrated on an example of plasmonic lattices embedded in a homogeneous ambience and placed inside and onto an optical waveguide. Localized surface plasmon resonances (LSPRs), lattice plasmon resonances (LPRs) and their hybridization with photonic guided modes are observed. High precision of this calculations is confirmed by comparison with finite element method (FEM).
Studying localized surface plasmon resonances in the THz region for subwavelength spiral disks
Authors: Gerasimov V V , Kuznetsov S A , Lemzyakov A G , Hafizov R R
Published: April 2020

Spoof localized surface plasmon resonances (LSPRs) in the THz range are promising for bio-sensing and spectroscopy. Using long spiral grooves allows improving the surface mode confinement of LSPRs in the long-wavelength region. Our numerical simulations of sub-wavelength spiral gold disks in the range of 0.04–6 THz have shown that in case of Drude conductivity and normal incidence of EM radiation only the first- and second-order dipole localized surface plasmon resonances (LSPRs) are excited. High order resonances arise at inclined incidence. The spectra and 2D distributions of the EM field at the resonant frequencies depend on the number of spiral arms and symmetry of the spiral structure.
Arbitrary-order optical differentiation in refection by sequence of first-order differentiators
Authors: Golovastikov Nikita V. , Bykov Dmitry A. , Doskolovich Leonid L.
Published: April 2020

We propose a simple analytical method for designing arbitrary-order optical differentiators operating in reflection by successively arranging several first-order optical differentiators. The approach is based on the scattering matrix analysis, does not involve numerical optimization and is valid for differentiators of arbitrary configurations. The numerical simulation results demonstrate high-quality differentiation of a picosecond pulse for up to the fourth order. The proposed method can find application in the design of analogue optical computing and optical information processing systems.
Engineering coupling in electromagnetic topological models via staggered bianisotropy
Authors: Gorlach M A , Zhirihin D V , Bobylev D A , Gorlach A A , Li S V , Sokolov D Y , Slobozhanyuk A P , Khanikaev A B
Published: April 2020

Magneto-electric coupling known also as bianisotropy plays a fundamental role in time-reversal-invariant photonic topological metamaterials being responsible for opening of a topological bandgap. To further uncover the fundamental link between bianisotropy and photonic topological states, we investigate scattering of light from the individual bianisotropic disk and reveal polarization dependence of scattering which provides a photonic analogue of spin Hall effect originating from the coupling between electric and magnetic responses of the disk. Based on the field patterns from the individual meta-atom, we further design a linear array of such bianisotropic disks. Employing coupled-dipole model, we demonstrate that local modification of the disk bianisotropy translates into the modification of coupling constants in the effective photonic Hamiltonian thus opening an avenue to engineer electromagnetic topological states via the staggered bianisotropy pattern. To confirm our findings, we realize a representative example of such one-dimensional array experimentally and detect the interface states at the domain wall.
The dependence of the exciton binding energies on quantum well widths of the donor doped GaAs/AlGaAs QW influencing on the intersubband transition
Authors: Dommelen Paphavee van , Jarusirirangsi Kanothai
Published: April 2020

In this research, we theoretically investigated the exciton binding energies as a function of QW widths with the variation of the percent alloy contents. For any certain percent of alloy contents, the exciton binding energies increase proportionally with the increasing of QW widths. We also simulated the exciton binding energies as a function of the percent alloy contents of AlxGa1-xAs barrier with the variation of QW widths. For the narrower QW widths, with any certain percent of alloy contents, the exciton binding energies show higher discrete energy characteristic compared with the wider well widths. These results can explain the intersubband transition with MIR and Far-IR emission between donor doped levels in conduction band.
Auger recombination via deep energy levels as a potential cause of efficiency droop in InGaN/GaN LEDs
Authors: Karpova A A , Samosvat D M , Zegrya G G
Published: April 2020

In the present work a mechanism of nonradiative radiation via deep energy levels is considered for InGaN/GaN LEDs from the first principles. The coefficient and time of such Auger recombination are evaluated numerically and are shown to be enough for causing the efficiency droop in blue and green InGaN/GaN LEDs.
Electron-photonic topological states on the surface of a bulk semiconductor driven by a high-frequency field
Authors: Kibis O. V. , Kyriienko O. , Shelykh I. A.
Published: April 2020

It is shown theoretically that the strong coupling of electrons in a bulk gapless semiconductor (HgTe) to a circularly polarized high-frequency electromagnetic field induces topological states on the surface of the semiconductor. Their branches lie near the center of the Brillouin zone and have the Dirac dispersion. Thus, the light-induced topological phase transition in the semiconductor appears. The structure of the found surface states is studied both analytically and numerically in the broad range of their parameters.
Floquet engineering of 2D materials
Authors: Kibis O. V. , Iorsh I. V. , Shelykh I. A.
Published: April 2020

We demonstrate theoretically that the interaction of electrons in the 2D materials (gapped graphene and transition metal dichalchogenide monolayer) with a strong off-resonant electromagnetic field substantially renormalizes their band structure, including the band gaps and the spin-orbit splitting. Moreover, the renormalized electronic parameters drastically depend on the field polarization. Namely, a linearly polarized field always decreases the band gap (and, particularly, can turn the gap into zero), whereas a circularly polarized field breaks the equivalence of valleys in different points of the Brillouin zone and can both increase and decrease corresponding band gaps. As a consequence, the field can serve an effective tool to control spin and valley properties of the 2D materials and be potentially exploited in optoelectronic applications.
Measurement surface plasmon polariton assisted optical force using a carbon nanowhisker mechanical resonator
Authors: Kislov D A , Mukhin I S , Golubok A O , Lukashenko S Yu , Shalin A S
Published: April 2020

Optical tweezers are widely used for manipulating nano- and micro sized particles. The presence of a special plasmon substrate can significantly affect the optical forces acting on an object. This paper discusses the possibility of experimental measuring optical plasmon forces using a mechanical resonator based on a carbon nanowhisker. A mathematical model describing the effect of optical forces on nanowhisker oscillations with an additional nanoparticle at the end is presented with taking into account the effect of surface plasmon waves on the substrate.
Q/V enhancement of Si micropillar resonator with Bragg reflectors in BIC regime
Authors: Kolodny Stanislav , Iorsh Ivan
Published: April 2020

Recent progress in nanophotonics is increasingly aimed at the use of fully dielectric nanoparticles that support magnetic and electric Mie resonances, but as the Mi theory predicts, dielectric subwavelength resonators have extremely low Q-values. However it has been shown that using so-called bound states in the continuum (BIC) allows to achieve high values of Q for high index cylindrical resonator. Here we show that the use distributed Bragg reflectors in regime of BIC allows to drastically increase the absolute values of quality factors, and what is even more important quality factor to mode volume ratio, the quantity proportional to the Purcell factor which is of the immense importance for triggering nonlinear optical processes in nanophotonic devices.
A simple calibration-free method of complex permittivity extraction
Authors: Kurdjumov S. , Filonov D. , Kretov E. , Ivanov V. , Ginzburg P.
Published: April 2020

Here we present a new calibration-free method for relative complex permittivity extraction, which allows using accessible and cheap materials and simplifies the measurement process. The method combines the advantages of resonant and non-resonant techniques and provides results for liquids and solids in 0.5-5GHz frequency band in dependence on the material type. The essence of the proposed method is based on measuring of the magnetic dipole resonance of a spherical sample. The size of such a sphere can be dynamically changed making it possible to evaluate its permittivity at different frequencies. Mie theory serves as the basis for connecting the resonant frequency of the sample with the real part of the permittivity, while imaginary part can be found from Q-factor. In this work we demonstrate the efficiency of the method for water. In addition, we evaluate the applicability of the method for lossy materials.
Mesoporous particles for transdermal delivery of the antifungal drug griseofulvin
Authors: Lengert E V , Averkhovskii R , Genina E A , Terentyuk G S , Svenskaya Y I
Published: April 2020

Griseofulvin is an antifungal antibiotic applying for the treatment of dermatophyte infections. The most common delivery route of this drug is oral. The dosage of griseofulvin varies depending on whether the drug is administered as a microsized or an ultramicrosized preparation. In order to avoid possible incidental systemic toxicity associated with the oral delivery route and reduce the therapeutic dose, a novel approach for the griseofulvin administration is proposed. Immobilization of the drug into mesoporous calcium carbonate particles together with their further ultrasonically-assisted topical application provides the efficient transdermal transportation. Accumulation of griseofulvin-loaded carriers inside hair follicles of the rat is demonstrated in vivo, allowing by this means the targeted delivery of the antifungal drug to the lesion area of skin. No significant toxicity of the system is shown for rat and human fibroblasts cells in vitro.
A new solution of permittivity and permeability measurement system with temperature variation
Authors: Letertre Thibaut , Jegou Carole , Pouliguen Philippe , Sabouroux Pierre
Published: April 2020

Nowadays, permittivity and permeability measurement are well-known in the industrial domain and research laboratory. It became unavoidable in few domains as biomedical and aeronautics. In this way, many researchers or engineers are committing to working on new measurement setup, complex or not working on a wide band of frequency. However, the thermal dependence of dielectric and magnetic structure is quite complicated to determinate, even though it became more and more important to know. As in the case of radomes antennas, the air friction produces increasing of temperature and thereby electromagnetic characteristics variation. Accordingly, we propose in this paper, a new characteristics measurement system of solid material between 100MHZ and 15GHz coupled to a high-temperature thermoregulation system designed to reach a few hundred degrees.