Angular dependence of the ferromagnetic resonance parameters of [Ti/FeNi]6/Ti/Cu/Ti/[FeNi/Ti]6 nanostructured multilayered elements in the wide frequency range

Magnetically soft [Ti(6)/FeNi(50)]6/Ti(6)/Cu(500)/Ti(6)/[FeNi(50)/Ti(6)]6 nanostructured multilayered elements were deposited by rf-sputtering technique in the shape of elongated stripes. The easy magnetization axis was oriented along the short size of the stripe using deposition in the external magnetic field. Such configuration is important for the development of small magnetic field sensors employing giant magnetoimpedance effect (GMI) for different applications. Microwave absorption of electromagnetic radiation was experimentally and theoretically studied in order to provide an as complete as possible high frequency characterization. The conductor-backed coplanar line was used for microwave properties investigation. The medialization for the precession of the magnetization vector in the uniformly magnetized GMI element was done on the basis of the Landau–Lifshitz equation with a dissipative Bloch–Bloembergen term. We applied the method of the complex amplitude for the analysis of the rotation of the ferromagnetic GMI element in the external magnetic field. The calculated and experimental dependences for the amplitudes of the imaginary part of the magnetic susceptibility tensor x-component and magnetoabsorption related to different angles show a good agreement. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 18-19-00090Funding: This research was funded by the Russian Science Foundation, grant number 18-19-00090

Bushes of Nonlinear Normal Modes in Single-Layer Graphene

In-plane vibrations in uniformly stretched single-layer graphene (space group P6mm), which are described by the Rosenberg nonlinear normal modes (NNMs) and their bushes, are studied with the aid of group-theoretical methods developed by authors in some earlier papers. It was found that only 4 symmetry-determined NNMs (one-dimensional bushes), as well as 14 two-dimensional bushes are possible in graphene. They are exact solutions to the dynamical equations of this two-dimensional crystal. The verification of group-theoretical results with the aid of ab initio simulations based on density functional theory is discussed

Regularized reconstruction in quantitative SPECT using CT side information from hybrid imaging

A penalized-likelihood (PL) SPECT reconstruction method using a modified regularizer that accounts for anatomical boundary side information was implemented to achieve accurate estimates of both the total target activity and the activity distribution within targets. In both simulations and experimental I-131 phantom studies, reconstructions from (1) penalized likelihood employing CT-side information-based regularization (PL-CT), (2) penalized likelihood with edge preserving regularization (no CT) and (3) penalized likelihood with conventional spatially invariant quadratic regularization (no CT) were compared with (4) ordered subset expectation maximization (OSEM), which is the iterative algorithm conventionally used in clinics for quantitative SPECT. Evaluations included phantom studies with perfect and imperfect side information and studies with uniform and non-uniform activity distributions in the target. For targets with uniform activity, the PL-CT images and profiles were closest to the 'truth', avoided the edge offshoots evident with OSEM and minimized the blurring across boundaries evident with regularization without CT information. Apart from visual comparison, reconstruction accuracy was evaluated using the bias and standard deviation (STD) of the total target activity estimate and the root mean square error (RMSE) of the activity distribution within the target. PL-CT reconstruction reduced both bias and RMSE compared with regularization without side information. When compared with unregularized OSEM, PL-CT reduced RMSE and STD while bias was comparable. For targets with non-uniform activity, these improvements with PL-CT were observed only when the change in activity was matched by a change in the anatomical image and the corresponding inner boundary was also used to control the regularization. In summary, the present work demonstrates the potential of using CT side information to obtain improved estimates of the activity distribution in targets without sacrificing the accuracy of total target activity estimation. The method is best suited for data acquired on hybrid systems where SPECT-CT misregistration is minimized. To demonstrate clinical application, the PL reconstruction with CT-based regularization was applied to data from a patient who underwent SPECT/CT imaging for tumor dosimetry following I-131 radioimmunotherapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85409/1/pmb10_9_007.pd

Functional and genomic analyses of α-solenoid proteins

{alpha}-solenoids are flexible protein structural domains formed by ensembles of alpha-helical repeats (Armadillo and HEAT repeats among others). While homology can be used to detect many of these repeats, some {alpha}-solenoids have very little sequence homology to proteins of known structure and we expect that many remain undetected. We previously developed a method for detection of {alpha}-helical repeats based on a neural network trained on a dataset of protein structures. Here we improved the detection algorithm and updated the training dataset using recently solved structures of {alpha}-solenoids. Unexpectedly, we identified occurrences of {alpha}-solenoids in solved protein structures that escaped attention, for example within the core of the catalytic subunit of PI3KC. Our results expand the current set of known {alpha}-solenoids. Application of our tool to the protein universe allowed us to detect their significant enrichment in proteins interacting with many proteins, confirming that {alpha}-solenoids are generally involved in protein-protein interactions. We then studied the taxonomic distribution of {alpha}-solenoids to discuss an evolutionary scenario for the emergence of this type of domain, speculating that {alpha}-solenoids have emerged in multiple taxa in independent events by convergent evolution. We observe a higher rate of {alpha}-solenoids in eukaryotic genomes and in some prokaryotic families, such as Cyanobacteria and Planctomycetes, which could be associated to increased cellular complexity. The method is available at http://cbdm.mdc-berlin.de/~ard2/

DIGITIZATION OF HOUSING AND PUBLIC UTILITIES AS A TOOL FOR MANAGING INVESTMENT PROGRAMS OF HEAT SUPPLY ORGANIZATIONS

The paper analyzes the level of normalized losses. The values of thermal energy losses during the flooding of the heat pipes of the channel gasket are calculated. The payback period of investment programs for the reconstruction of heating networks using polyurethane foam insulation has been obtained.В работе проанализирован уровень нормируемых потерь. Рассчитаны значения потерь тепловой энергии при затоплении теплопроводов канальной прокладки. Получены сроки окупаемости инвестиционных программ по реконструкции тепловых сетей с применением пенополиуретановой изоляции

МОДЕРНІЗАЦІЯ КОМПЛЕКСУ ТИПУ ІК-1У ДЛЯ ВИМІРЮВАННЯ ОПОРУ ЗАЗЕМЛЮВАЛЬНОГО ПРИСТРОЮ БЛИСКАВКОВІДВОДІВ ТА ОПОР ЛЕП

Purpose. The creation of a measuring device for determining the impedance of the grounding of lightning arresters and supports of overhead lines under the influence of aperiodic pulses with the parameters 1.2/50 μs, 8/20 μs and 10/350 μs. Methodology. For this purpose, electrical engineering theory, transient modeling software and natural modeling methods are used. Results. The parameters of the electrical circuits of the additional forming unit were determined to create lightning current pulses with parameters of 10/350 μs using the IK-1U measuring complex. According to the simulation results, a layout of the forming unit in the form of an attachment and the IK-1U complex with the upgraded power supply system were created. Oscillograms of the front and pulse duration are obtained. The specified model was tested when performing electromagnetic diagnostics of the state of the RFP for more than 100 operating electrical substations. Originality. The measuring complex IK-1U was improved, which made it possible to determine the impulse impedance of the grounding device of lightning arresters when exposed to a current of 10/350 μs, 8/20 μs and of voltages 1.2/50 μs. Practical value. Upgraded device allows measurements in accordance with modern international requirements. Метою роботи є створення вимірювального приладу для визначення опору заземлювальних пристроїв (ЗП) блискавковідводів та опор повітряних ліній електропередачі (ЛЕП) при дії аперіодичних імпульсів напруги з параметрами 1,2/50 мкс та струму з параметрами 8/20 мкс і 10/350 мкс. Для цього використано теорію електротехніки, програмні засоби моделювання перехідних процесів та методи натурного моделювання. Було визначено параметри елементів електричного кола додаткового формуючого блоку для створення грозових імпульсів струму з параметрами 10/350 мкс за допомогою вимірювального комплексу типу ІК-1У. Вдосконалено комплекс типу ІК-1У, що дозволило визначати імпульсний опір ЗП блискавковідводів та опор ЛЕП при дії імпульсів струму 10/350 мкс, 8/20 мкс та напруги 1,2/50 мкс. Модернізований прилад дозволяє проводити вимірювання відповідно з сучасними міжнародними вимогами

Penning Spectroscopy and Structure of Acetylene Oligomers in He Nanodroplets

Embedded atoms or molecules in a photoexcited He nanodroplet are well-known to be ionized through inter-atomic relaxation in a Penning process. In this work, we investigate the Penning ionization of acetylene oligomers occurring from the photoexcitation bands of He nanodroplets. In close analogy to conventional Penning electron spectroscopy by thermal atomic collisions, the n = 2 photoexcitation band plays the role of the metastable atomic $1s2s$ $^{3,1}S$ He$^\ast$. This facilitates electron spectroscopy of acetylene aggregates in the sub-kelvin He environment, providing the following insight into their structure: The molecules in the dopant cluster are loosely bound van der Waals complexes rather than forming covalent compounds. In addition, this work reveals a Penning process stemming from the n = 4 band where charge-transfer from autoionized He in the droplets is known to be the dominant relaxation channel. This allows for excited states of the remnant dopant oligomer Penning-ions to be studied. Hence, we demonstrate Penning ionization electron spectroscopy of doped droplets as an effective technique for investigating dopant oligomers which are easily formed by attachment to the host cluster.Comment: 22 pages, 1 png figure, 4 postscript figure

Delocalized nonlinear vibrational modes in graphene: second harmonic generation and negative pressure

With the help of molecular dynamics simulations, delocalized nonlinear vibrational modes (DNVM) in graphene are analyzed. Such modes are dictated by the lattice symmetry, they are exact solutions to the atomic equations of motion, regardless the employed interatomic potential and for any mode amplitude (though for large amplitudes they are typically unstable). In this study, only one‐ and two‐component DNVM are analyzed, they are reducible to the dynamical systems with one and two degrees of freedom, respectively. There exist 4 one‐component and 12 two‐component DNVM with in‐plane atomic displacements. Any two‐component mode includes one of the one‐component modes. If the amplitudes of the modes constituting a two‐component mode are properly chosen, periodic in time vibrations are observed for the two degrees of freedom at frequencies ω and 2ω, that is, second harmonic generation takes place. For particular DNVM, the higher harmonic can have frequency nearly two times larger than the maximal frequency of the phonon spectrum of graphene. Excitation of some of DNVM results in the appearance of negative in‐plane pressure in graphene. This counterintuitive result is explained by the rotational motion of carbon hexagons. Our results contribute to the understanding of nonlinear dynamics of the graphene lattice

Inelastic scattering of photoelectrons from He nanodroplets

We present a detailed study of inelastic energy-loss collisions of photoelectrons emitted from He nanodroplets by tunable extreme ultraviolet (XUV) radiation. Using coincidence imaging detection of electrons and ions, we probe the lowest He droplet excited states up to the electron impact ionization threshold. We find significant signal contributions from photoelectrons emitted from free He atoms accompanying the He nanodroplet beam. Furthermore, signal contributions from photoionization and electron impact excitation/ionization occurring in pairs of nearest-neighbor atoms in the He droplets are detected. This work highlights the importance of inelastic electron scattering in the interaction of nanoparticles with XUV radiation