bluuebunny/crossref_metadata_2025 huggingface dataset:
Высоковольтные светодиодные кристаллы AlInGaN
Authors: Марков Л.К. , Кукушкин М.В. , Павлюченко А.С. , Смирнова И.П. , Иткинсон Г.В. , Осипов О.В.
Published: October 2019

AbstractA high-voltage light-emitting diode (LED) flip chip based on an AlInGaN heterostructure is developed and fabricated. The LED flip chip consists of 16 elements connected in series, each of which is a convential LED. The chip with a total area of 1.25 × 1.25 mm is intended for a working current of 20 mA and a forward voltage of 48 V. To improve the current-distribution uniformity over the active region of the chip elements and to minimize the losses of the element area occupied by the n -type contact, the n -type contact pads in them are arranged inside the p -type contact region due to the two-level metallization layout with an intermediate insulating layer of dielectric. The arrangement topology of the contact pads is developed using numerical simulation. An increase in the quantum efficiency of the chip is provided by the application of combinations of metals with a high reflectance at the LED emission wavelength, which are used when fabricating n - and p -type contacts as well as current-carrying strips.
Изменение люминесцентных характеристик полупроводниковых гетероструктур при ионно-лучевом травлении
Authors: Левицкий Я.В. , Митрофанов М.И. , Вознюк Г.В. , Николаев Д.Н. , Мизеров М.Н. , Евтихиев В.П.
Published: October 2019

Ion-beam etching of AlGaAs / GaAs heterostructures leads to the occurrence of radiation defects and, as a result, luminescence quenching. Annealing at 620 ° C in an As atmosphere makes it possible to achieve almost complete recovery of the quantum luminescence efficiency for the case of radiation defects occurring at a distance of up to 150 nm from the heterojunction.
Фазовый состав, морфология, оптические и электронные характеристики наноразмерных пленок AlN, выращенных на подложках GaAs(100) с разориентацией
Authors: Середин П.В. , Федюкин А.В. , Терехов В.А. , Барков К.А. , Арсентьев И.Н. , Бондарев А.Д. , Фомин Е.В. , Пихтин Н.А.
Published: October 2019

Thin nano-sized aluminum nitride films on GaAs (100) substrates with varying degrees of misorientation with respect to the <100> direction can be obtained by reactive ion-plasma deposition.
It is shown that growth on substrates with different degrees of mismatch from the <100> direction leads to the growth of an AlN film with different phase composition and crystalline state. An increase in the degree of misorientation in the GaAs substrate used for growth is reflected both in the structural quality of nanoscale AlN films and in their electron structure, surface morphology, and optical properties.
Thus, the management of the morphology, surface composition and optical functional characteristics of AlN/GaAs heterophase systems can be achieved by using the degree of misorientation of the GaAs substrates.
ЯМР-исследование полуметалла Вейля WTe-=SUB=-2-=/SUB=- ниже температуры топологического перехода
Authors: Антоненко А.О. , Чарная Е.В. , Lee M.K. , Chang L.J. , Haase J. , Наумов С.В. , Доможирова А.Н. , Марченков В.В.
Published: October 2019

We carried out 125Te NMR studies of a WTe2 topological Weyl semimetal at temperatures of 41 and 293 K. Measurements were performed using a pulse Bruker Avance 500 NMR spectrometer. 125Te NMR spectra were obtained for the WTe2 single crystal at the orientation of the crystalline c axis parallel and perpendicular to the quantized field. We ascribed the complex spectra to four non-equivalent tellurium sites in the WTe2 crystalline structure. The recovery of the longitudinal magnetization was studied after the pulse saturation of particular lines in the spectra. We observed the single-exponential relaxation. The frequency shifts and widths of the spectral lines differed insignificantly at two temperatures while the spin-lattice relaxation times at 41 K were by a factor of approximately 30 greater than the relevant times at room temperature. Strong temperature dependence of relaxation was suggested to be due to the contribution of Weyl quasi-particles below the topological phase transition.
Электронная структура молибдена, окисленного на воздухе
Authors: Дементьев П.А. , Иванова Е.В. , Лапушкин М.Н. , Смирнов Д.А. , Тимошнев С.Н.
Published: October 2019

In situ photoelectron spectroscopy studies in ultrahigh vacuum of the electronic structure of the surface of molybdenum oxidized in air and during the adsorption of sodium Na with submonolayer coatings were carried out. The spectra of photoemission from the valence band and the core levels O 1s, O 2s, Mo 4s and Na 2p were studied under synchrotron excitation in the photon energy range of 80 – 600 eV. The change in the spectrum of the oxygen core levels associated with the substitution of hydrogen atoms in the hydroxyl group by sodium atoms was found. The surface topography and cathodoluminescence of molybdenum oxide were studied.
Влияние химического состава кристаллов TlIn-=SUB=-1-x-=/SUB=-Er-=SUB=-x-=/SUB=-S-=SUB=-2-=/SUB=- (0≤ x≤0.01) на их диэлектрические характеристики и параметры локализованных состояний
Authors: Мустафаева С.Н. , Асадов М.М.
Published: October 2019

The frequency dependences of the real (ε) and imaginary (ε ″) components of the complex dielectric constant, tangent of dielectric loss (tan) and ac conductivity (σac) of the obtained TlIn1-хErхS2 (0  x  0.01) crystals have been studied in the frequency range f = 5104–3.5107 Hz. It is established that in TlIn1-хErхS2 a relaxation dispersion of ε and ε″ takes place. The effect of erbium concentration (Er) in TlIn1-хErхS2 crystals on their dielectric coefficients was studied. In the high frequency range, the ac conductivity of TlIn1-хErхS2 crystals obeyed the σac ~ f 0.8 law, which is characteristic of a hopping charge transfer mechanism at states localized near the Fermi level. The parameters of states localized in the band gap and the influence of the chemical composition of the TlIn1-хErхS2 crystals on these parameters are estimated.
Подвижность носителей заряда в монокристалле и нанокерамике суперионного проводника Pb-=SUB=-1-x-=/SUB=-Sn-=SUB=-x-=/SUB=-F-=SUB=-2-=/SUB=- (x=0.2)
Authors: Сорокин Н.И.
Published: October 2019

AbstractA crystallophysical model of ion transfer in the superionic Pb_1 – _ x Sn_ x F_2 conductor with a fluorite (CaF_2) structure is proposed. The concentration dependence of the ionic conductivity of Pb_1 – _ x Sn_ x F_2 single crystals and poly- and nanocrystals is analyzed. The single-crystal form of the superionic conductor is characterized by the highest conductivity. The mobility and concentration of anionic charge carriers in a single crystal and ceramics of Pb_1 – _ x Sn_ x F_2 ( x = 0.2) is calculated on the basis of structural and electrophysical data. The mobility of carriers μ_mob = 2.5 × 10^–6 cm^2/s V (at 293 K) in a single crystal is seven times higher than in nanoceramic. The concentration of carriers n _mob = 1.7 × 10^21 and 3.6 × 10^21 cm^3 (4.5 and 9.5% of the total number of anions) for a single crystal and nanoceramic, respectively. The comparison of isostructural Pb_0.8Sn_0.2F_2, Pb_0.67Cd_0.33F_2, and Pb_0.9Sc_0.1F_2.1 single crystals shows that anionic carriers have a maximum mobility in the β-PbF_2 and SnF_2 based solid solution.
Нелинейная динамика формирования периодической сверхструктуры примесных полос при быстрой направленной кристаллизации бинарных сплавов
Authors: Чеврычкина А.А. , Бессонов Н.М. , Корженевский А.Л.
Published: October 2019

The article offers an analytical description of the nonlinear dynamics of the formation of regular impurity superstructures during the rapid crystallization of binary alloys, supplemented by numerical model calculations. The existence of a stable limit cycle is shown and the spatial profiles of the impurity concentration in a solid product are calculated. It has been established that considering the finiteness of the velocity of jumps of impurity atoms leads to a very significant decrease in the size of the cycles and a change in the profiles of the impurity superstructures.
Физика интерференции квантовых частиц
Authors: Ганцевич С.В. , Гуревич В.Л.
Published: October 2019

The bra+ket quantum language introduced earlier by the authors for the explanation
of quantum correlation at macroscopic distances permit to understand the physical mechanism of the interference of separate quantum particles without the concepts of
the transformation of a wave into a particle or vice versa as well as to avoid the assertions of retrocausality, nonlocality, instantaneous interaction or other similar phenomena allegedly inherent to quantum mechanics. Using the bra+ket approach we consider the experiments with two and three slits, the delayed choice experiments and some more complicated interference experiments with changing parameters the results of which caused the vivid many year discussion with adverse conclusions on particle trajectories in the interferometers.
Экситоны и трионы в двухслойных ван-дер-ваальсовых гетероструктурах
Authors: Семина М.А.
Published: October 2019

The theoretical study of excitons and trions in bilayer structures based on transitional metal diсhalcogenides is carried out. The expressions for effective interaction between charge carriers in such a system with taking into account the dielectric contrast had been obtained. The simple and physically relevant trial functions for electron-hole complexes were suggested. The variational calculation of the dependences of exciton and trion binding energies on the interlayer separation was made with taking into account the details of the screening of the Coulomb interaction. The accuracy of the variational approach is validated by the direct numerical calculation of the exciton binding energy as a function of the interlayer distance.
Получение нанокомпозитов МУНТ/MnO-=SUB=-2-x-=/SUB=-, МУНТ/MnO-=SUB=-2-x-=/SUB=-/CuO и исследования их газочувствительных свойств
Authors: Стенькин Ю.А. , Болотов В.В. , Соколов Д.В. , Росликов В.Е. , Ивлев К.Е.
Published: October 2019

Nanocomposites based on multiwalled carbon nanotubes (MWCNT) with manganese dioxide (MnO2-x) and copper oxide (CuO) were obtained and investigated. The morphology and elemental composition of MWCNT-layer and nanocomposites MWCNT/MnO2-х, MWCNT/MnO2-х/CuO were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing response of MWCNT-layer and nanocomposites upon exposure to hydrogen sulfide (H2S) and nitrogen dioxide (NO2) was demonstrated at room temperature. Effect of increasing the conductivity of MWCNT-layer and nanocomposites upon exposure to NO2 indicates these nanomaterials have conductive of p-type. Copper oxide in nanocomposite significantly enhances the gas sensing response to H2S.
Поли-2(1-циклопент-2-ен-1-ил)анилин: синтез и исследование электрофизических и физико-химических свойств
Authors: Биглова Ю.Н. , Салихов Р.Б. , Сафаргалин И.Н. , Салихов Т.Р. , Мустафин А.Г.
Published: October 2019

The synthesis of a new electron-donating conductive polymer –2- (1-cyclopent-2-en-1-yl) aniline was carried out and the polymerization process was optimized by the mole ratio of monomer: oxidizer and reaction time. The extraction and solubility of functionalized polyaniline in typical organic solvents differing in polarity are evaluated. For the obtained high-molecular compound, the dependence of the electrical conductivity on temperature was studied, the carrier mobility was calculated, and a thermogravimetric analysis was performed.
Моделирование процесса коррекции локальных ошибок формы поверхности малоразмерным ионным пучком
Authors: Чернышев А.К. , Малышев И.В. , Пестов А.Е. , Чхало Н.И.
Published: October 2019

The algorithm for solving the problem of local surface shape errors correction by small-size ion beam is proposed in the paper. The algorithm involves a sequential search of heights relative to the average value with the aim to find the most optimal etching point that satisfies the criterion - reducing the sum of the modules of the derivatives on the etching spot. It is shown that the new approach makes it possible to significantly expand the range of spatial frequencies that can be influenced at a given size of the ion beam.
Функциональные блоки магнонных сетей на основе структур с нарушением трансляционной симметрии
Authors: Мартышкин А.А. , Садовников А.В. , Бегинин Е.Н. , Никитов С.А.
Published: October 2019

AbstractWe have studied the properties of spin-wave excitations in a structure that is a junction of two regular magnon waveguides. The proposed structure enables the transmission of spin-wave signals in an irregular structure in the propagation mode of a surface magnetostatic wave. Using the method of micromagnetic simulation, the characteristics of the wave process have been calculated when changing the structure parameters, magnitude and direction of a magnetization field. It is shown that a system with translational symmetry violation can be used to transmit a signal in three-dimensional configurations of magnon networks.
Изготовление и исследование свойств вогнутого кристаллического зеркала для проекта КОРТЕС
Authors: Ахсахалян А.А. , Ахсахалян А.Д. , Гарахин C.А. , Ерхова Н.Ф. , Кириченко А.С. , Кузин С.В. , Салащенко Н.Н. , Торопов М.Н. , Чхало Н.И.
Published: October 2019

The manufacturing method is described and the results of the study of the X-ray optical properties of a concave spherical mirror made of crystalline quartz are presented. The radius of curvature was 1630 mm. The shape of the mirror surface was studied on an interferometer with a diffraction wave of comparison. It was shown that in the whole processing area the maximum deviation from the nearest sphere was about 0.2 μm, and the square root of rms is 34 nm, which ensures high quality of images with an angular error of 2” (angular seconds). The reflection coefficients (about 7%) and the lower estimate of the spectral selectivity (λ / delta λ = 1775) are determined in the vicinity of the wavelength λ = 0.834 nm, which is close to the working wavelengths of the MgXII doublet (λ = 0.8418 and 0.8423 nm). During the bending of the crystal mirror, no change in the position of the Bragg peak and spectral selectivity was found within the limits of the accuracy of measurements.
Многослойные зеркала Ag/Y для спектрального диапазона 9-11 nm
Authors: Квашенников Д.С. , Зуев С.Ю. , Полковников В.Н. , Салащенко Н.Н. , Чхало Н.И. , Delmotte F. , Meltchakov E.
Published: October 2019

AbstractMultilayer Ag/Y mirrors intended for the spectral range of 9–11 nm have been investigated. The parameters of mirrors, specifically, the thicknesses of transition layers, have been determined. The efficiency of B_4C and Si barrier layers has been demonstrated. It has been shown that the properties of structures like Ag/Y and Ag/Y with B_4C and Si barriers layers have poor temporal stability. The highest reflection coefficient of 18% at a wavelength of 9.34 nm, has been observed for the Ag/Si/Y structure. The same structure has the best temporal stability.
Ошибки измерений интерферометров с дифракционной волной сравнения
Authors: Ахсахалян А.А. , Гаврилин Д.А. , Малышев И.В. , Салащенко Н.Н. , Торопов М.Н. , Уласевич Б.А. , Цыбин Н.Н. , Чхало Н.И.
Published: October 2019

The paper describes the experimental stand and the results of studies of aberrations of the sources of a reference spherical wave (SRSW) based on a single-mode optical fiber with a sub-wave output aperture using the optical part of the recording system (OPRS). SRSW and OPRS are being developed for a referenceless interferometer with a diffraction reference wave. The technique to minimize measurement errors is described. Developed SRSW and OPRS provide subnanometer optics measurement accuracy. The possibilities of improving the accuracy of interferometer measurements to the picometer level are discussed.
Оптическое излучение плазменных струй атмосферного давления, возбуждамых барьерным разрядом
Authors: Генерал А.А.
Published: October 2019

In the spectral range 270–900 nm luminescence spectra experimentally investigated plasma jets formed a barrier discharge in atmospheric pressure in an argon-air mixtures, and helium-air. It is shown that the emission spectra generated by the plasma jets are mainly represented by electron-vibration transitions of the second positive system of neutral nitrogen molecules. The radiation powers of these mixtures are compared.
Сравнение методов Радона-Никодима и многостадийной модели релаксации при анализе динамики флуоресценции ансамбля холодных атомов
Authors: Божокин С.В. , Курапцев А.С.
Published: October 2019

Abstract The fluorescence of cold atoms, cooled to ultra-low temperatures and excited by pulsed laser radiation, is calculated. The fluorescence of cold atoms is calculated based on the solution of the non-steady-state Schrödinger equation for a combined system of atoms and an electromagnetic field. A universal function is proposed in the work showing the deviation of the fluorescence decay at the end of the pulse from the single-exponential model. To analyze the dynamics of fluorescence, a Radon–Nikodym method has been used based on the studies on the eigenvalues of a matrix constructed on the basis of the fluorescence signal. It is shown that a correlation exists between the parameter of distribution asymmetry inherent in signal matrix eigenvalues, and the temporal law of fluorescence decay. As an alternative method of fluorescence analysis, a multistage relaxation model is used, caused by collective multiatomic effects. The values of characteristic amplitude and relaxation time both at short times (“superradiance”) and at long times (“subradiance”) have been found.
Спектрально-люминесцентные свойства разнолигандных комплексных соединений европия(III) с n-метилбензойной кислотой
Authors: Калиновская И.В. , Задорожная А.Н.
Published: October 2019

Abstract The spectral-luminescent properties of europium(III) complexes with p -methylbenzoic acid and nitrogen- and phosphorus-containing neutral ligands of compositions [Eu( p -MBA)_3 · D]_2 · x H_2O and [Eu( p ‑MBA)_3 · 2H_2O]_ n , where p -MBA is the anion of p -methylbenzoic acid and D is 1,10-phenanthroline (phen), 2,2' dipyridyl (dipy), triphenylphosphine oxide (tppo) ( х = 0), hexamethylphosphortriamide (hmpa) ( x = 1), or benzotriazole (bt) ( x = 2) are studied. The electronic absorption spectra, the luminescence excitation spectra, and the Stark structure of ^5 D _0−^7 F _ j (  j = 0–2) electronic transitions in low-temperature luminescence spectra of complex europium(III) p -methylbenzoates are analyzed. It is found that the excitation energy transfer to europium ions occurs from the levels of both p -methylbenzoic acid and neutral ligands.
Оптические свойства нестехиометрического оксида кремния SiO-=SUB=-x-=/SUB=- (x<2)
Authors: Кручинин В.Н. , Перевалов Т.В. , Камаев Г.Н. , Рыхлицкий С.В. , Гриценко В.А.
Published: October 2019

Abstract The optical properties of amorphous nonstoichiometric silicon oxide (SiO_ x ) films of variable composition ( x = 0 . 62–1 . 92) formed by plasma-enhanced chemical vapor deposition are studied in the spectral range of 1 . 12–4 . 96 eV. Spectral ellipsometry showed that the refractive index dispersion character allows one to assign the formed SiO_ x films to silicon-like films, dielectrics, or intermediate-conductivity-type films depending on the content of oxygen in the gas phase during synthesis. A model of the SiO_ x structure for ab initio calculations is proposed and describes well the experimental optical spectra. Ab initio calculations of the dependences of the SiO_ x refractive index and band gap on stoichiometry parameter x are performed.
Управляемый логический вентиль на четырехузловом линейном гибридном кластерном состоянии
Authors: Тихонов K.С. , Манухова A.Д. , Королёв С.Б. , Голубева T.Ю. , Голубев Ю.M.
Published: October 2019

In the case of a large number of quantum calculations, a situation may arise when the intermediate results of the calculations need to be stored for a given time. This work shows how to create a hybrid atom-light cluster state and realize a CZ gate in such a way that the results of its implementation are stored on long-lived degrees of freedom of the atomic ensemble and can be preserved for a long time.
Влияние протонного облучения на свойства стекла с покрытием ITO
Authors: Хасаншин Р.Х. , Новиков Л.С.
Published: October 2019

Changes in the surface morphology and optical properties of K208 glass samples with an ITO film as a result of exposure to 20-keV protons at a dose of 0.2–1.0 mC/cm2 and a proton current density of 9 nA/cm2 were studied. It has been experimentally shown that the presence of an ITO film affects the nature of the change in morphology and is the main cause of the degradation of the optical properties of samples during proton irradiation.
Эллипсометрическое исследование тонкопленочных структур аморфного гидрогенизированного углерода и наночастиц золота
Authors: Толмачев В.А. , Щербинин Д.П. , Коншина Е.А.
Published: October 2019

In this work, the optical constant films of amorphous hydrogenated carbon (a-C: H) and a hybrid structure based on it with a granulated gold film before and after their annealing at 300 °C were studied by spectral ellipsometry. The dispersions n (λ) and k (λ) of the a-C:H film were established using the Cauchy approximation and its thickness. The spectral features of the Au plasmon nanoparticle layer deposited on the a-C:H surface were modeled as an effective medium and a Lorentz oscillator. The parameters of the films and their thickness were determined by fitting the calculated spectra to the ellipsometric spectra  (λ) and  (λ). The obtained data were used to determine the parameters of the Lorentz oscillator in the model of a-C:H / Au two-layer structure. As a result of the a-C:H / Au structure annealing, the intensity of the maxima in the spectra n and k increased, their position shifted to the blue region, and the half-width of the bands decreased. The observed changes in the ellipsometric spectra are completely consistent with the spectrophotometric data of this structure.
Влияние уровня легирования исходных монокристаллов кремния на параметры структуры пористого кремния, полученного методом электрохимического травления
Authors: Зегря А.Г. , Соколов В.В. , Зегря Г.Г. , Ганин Ю.В. , Михайлов Ю.М.
Published: October 2019

AbstractThe effect of comparatively small changes in the free carrier concentration in a heavily doped p ‑type single-crystal silicon on the structural parameters of porous layers formed as a result of its anodic etching has been found. The pronounced influence exerted by the hole concentration on the structural porous silicon parameters being studied is explained on the basis of the concept of electrochemical pore-formation in silicon crystals as a self-organized cooperative process accompanied by the injection of electrons from the region of the chemical reaction at the propagation front of pores.
Формирование в ПММА широкополосных центров окраски фемтосекундным лазерным излучением
Authors: Калиничев А.А. , Смирнова О.С. , Поволоцкий А.В.
Published: October 2019

To date, organic materials treated with laser radiation have been increasingly used in the design and manufacture of optical elements. PMMA is one of the widely used polymeric materials in optics and optoelectronics. The main advantages of PMMA are a wide transparency window, and ease of industrial processing. Laser modification of PMMA allows creating color centers with radiation in a wide spectral range.
Исследование зеренной структуры мишеней SmS, полученных при различных условиях
Authors: Волчков И.С. , Баскаков Е.Б. , Стрелов В.И. , Каневский В.М.
Published: October 2019

The grains structure of samples of а SmS targets, obtained by pressing methods without and with the use of subsequent high-temperature processing by high- frequency currents (further HFC), under various pressure was investigated. The density of samples obtained under different conditions was determined. The optimal technological conditions for obtaining high-quality targets of a samarium monosulfide are determined: high-frequency annealing with pressing under pressure of 5t/cm 2 is more effective than high-frequency current annealing with pressing under pressure of 4 t/cm 2 . A significant content of unbound metallic samarium in samples obtained by pressing at 5 t/cm 2 but not subjected to high-temperature HFC annealing has been established.
Электрохимическая аморфизация как метод повышения скоростных характеристик кристаллических кремниевых анодов для литий-ионных аккумуляторов
Authors: Ли Г.В. , Астрова Е.В. , Румянцев А.М.
Published: October 2019

Anodes made of macroporous silicon were studied. The galvanostatic cyclic tests carried out in half-cells with a Li counter electrode in the mode, when charging capacity was limited by Q1 = 1000 mAh/g, showed that the inclusion into the test program of a modifying cycle with an increased time of electrochemical lithiation allows to increase the charge/discharge rate upon the returning back to the initial mode. To interpret the obtained results, a two-phase model with a sharp a-LixSi/c-Si boundary was used. The introduction of a larger amount of lithium during the modifying cycle leads to an increase in the thickness of the amorphous layer, within which the introduction and extraction of lithium in subsequent cycles occur at a higher rate.
Необычный механизм релаксации напряжений несоответствия в тонких нанопленках
Authors: Труханов Е.М. , Тийс С.А.
Published: October 2019

A new mechanism for the relaxation of misfit stresses in nanofilms with different density of surface phases has been established. It is ensured by mass transfer ordering in the stressed atomic layer. During the 7 × 7 → 5 × 5 phase transition in the Ge film on Si (111) substrate, the partial compensation of the compressive stresses occurs at the interface between the Ge crystal and its superstructure due to tensile deformation in surface phase loose layers.
Изучение структуры течения в перспективном вихревом топочном устройстве
Authors: Алексеенко С.В. , Ануфриев И.С. , Шадрин Е.Ю. , Шарыпов О.В.
Published: October 2019

The internal aerodynamics of isothermal laboratory model of improved four-vortex furnace of pulverized coal boiler are experimentally investigated. Using the particle image velocimetry method, the distribution of components of the air flow averaged velocity and the streamlines are obtained in a number of model cross sections for different operating modes of the furnace, determined by the ratio of the flow velocities supplied through the primary and secondary nozzles. The conditions for the formation of a stable flow structure with four symmetric conjugate vortices in the entire volume of the furnace, as well as the range of operating parameters leading to a spatially irregular vortex structure are determined.
Ударное и "задержанное" повреждение поверхности керамики ZnS-CVD
Authors: Щербаков И.П. , Дунаев А.А. , Синани А.Б. , Чмель А.Е.
Published: October 2019

Impact and impeded damage of ZnS-CVD ceramics surface

I.P. Shcherbakov, A.A. Dunaev, A.B. Sinani, A.E. Chmel

Localized damage of the surface of ductile ZnS ceramics synthesized by the chemical vapor deposition (CVD) method was performed by either impact of a pointed striker or by the impeded indenting of a Vickers pyramid. In both cases, the time series of acoustic emission pulses were recorded. The duration of the impact-induced sound emission was of 0.3-0.5 ms, while the indenting-produced active phase of emission was of 3-5 ms in length. The primary emission followed by the irradiation of weak acoustic signals during 80-100 ms. The statistical analysis of the time series showed the exponential (poissonian) energy distribution in impact-induced pulses, while in indented specimens, the distribution function followed a power law of the Gutenberg-Richter type. Considering that dislocation clusters serve as weak points for the crack nucleation, the difference in the mode of energy yield was explained by varying temporal pattern characteristics of the strain-stimulated dislocation motion in different time domains.
Перколяционные переходы на электризованной поверхности
Authors: Кузьмин Ю.И. , Плешаков И.В.
Published: October 2019

Percolation charge transport on an electrified surface under the adsorption of an electrically conductive phase is considered for the first time. The influence of adsorption and nucleation kinetics on the formation of percolation clusters, which allow the excess charge to flow off and to be subsequently neutralized, is studied. It is revealed that the percolation transitions are crucial in the stability of the electrostatic charge accumulated on a dielectric surface. It is found that the increase in both the spontaneous nucleation rate and the initial surface fraction covered by an electrically conductive phase leads to a drop in the percolation transition time.
Engagement and Participant Experiences With Consumer Smartwatches for Health Research: Longitudinal, Observational Feasibility Study
Authors: Beukenhorst Anna L , Howells Kelly , Cook Louise , McBeth John , O'Neill Terence W , Parkes Matthew J , Sanders Caroline , Sergeant Jamie C , Weihrich Katy S , Dixon William G
Published: October 2019

Background

Wearables provide opportunities for frequent health data collection and symptom monitoring. The feasibility of using consumer cellular smartwatches to provide information both on symptoms and contemporary sensor data has not yet been investigated.

Objective

This study aimed to investigate the feasibility and acceptability of using cellular smartwatches to capture multiple patient-reported outcomes per day alongside continuous physical activity data over a 3-month period in people living with knee osteoarthritis (OA).

Methods

For the KOALAP (Knee OsteoArthritis: Linking Activity and Pain) study, a novel cellular smartwatch app for health data collection was developed. Participants (age ≥50 years; self-diagnosed knee OA) received a smartwatch (Huawei Watch 2) with the KOALAP app. When worn, the watch collected sensor data and prompted participants to self-report outcomes multiple times per day. Participants were invited for a baseline and follow-up interview to discuss their motivations and experiences. Engagement with the watch was measured using daily watch wear time and the percentage completion of watch questions. Interview transcripts were analyzed using grounded thematic analysis.

Results

A total of 26 people participated in the study. Good use and engagement were observed over 3 months: most participants wore the watch on 75% (68/90) of days or more, for a median of 11 hours. The number of active participants declined over the study duration, especially in the final week. Among participants who remained active, neither watch time nor question completion percentage declined over time. Participants were mainly motivated to learn about their symptoms and enjoyed the self-tracking aspects of the watch. Barriers to full engagement were battery life limitations, technical problems, and unfulfilled expectations of the watch. Participants reported that they would have liked to report symptoms more than 4 or 5 times per day.

Conclusions

This study shows that capture of patient-reported outcomes multiple times per day with linked sensor data from a smartwatch is feasible over at least a 3-month period.

International Registered Report Identifier (IRRID)

RR2-10.2196/10238
Digitalizing Health Services by Implementing a Personal Electronic Health Record in Germany: Qualitative Analysis of Fundamental Prerequisites From the Perspective of Selected Experts
Authors: Pohlmann Sabrina , Kunz Aline , Ose Dominik , Winkler Eva C , Brandner Antje , Poss-Doering Regina , Szecsenyi Joachim , Wensing Michel
Published: October 2019

Background

The implementation of a personal electronic health record (PHR) is a central objective of digitalization policies in the German health care system. Corresponding legislation was passed with the 2015 Act for Secure Digital Communication and Applications in the Health Sector (eHealth Act). However, compared with other European countries, Germany still lags behind concerning the implementation of a PHR.

Objective

In order to explore potential barriers and facilitators for the adoption of a PHR in routine health care in Germany, this paper aims to identify policies, structures, and practices of the German health care system that influence the uptake and use of a PHR.

Methods

A total of 33 semistructured interviews were conducted with a purposive sample of experts: 23 interviews with different health care professionals and 10 interviews with key actors of the German health care system who were telematics, eHealth, and information technology experts (eHealth experts). The interviews were transcribed verbatim and subjected to a content analysis.

Results

From the expert perspective, a PHR was basically considered desirable and unavoidable. At the same time, a number of challenges for implementation in Germany have been outlined. Three crucial themes emerged: (1) documentation standards: prevailing processes of the analog bureaucratic paper world, (2) interoperability: the plurality of actors and electronic systems, and (3) political structure: the lack of clear political regulations and political incentive structures.

Conclusions

With regard to the implementation of a PHR, an important precondition of a successful digitalization will be the precedent reform of the system to be digitized. Whether the recently passed Act for Faster Appointments and Better Care will be a step in the right direction remains to be seen.
Usability Evaluations of Mobile Mental Health Technologies: Systematic Review
Authors: Inal Yavuz , Wake Jo Dugstad , Guribye Frode , Nordgreen Tine
Published: October 2019

Background

Many mobile health (mHealth) apps for mental health have been made available in recent years. Although there is reason to be optimistic about their effect on improving health and increasing access to care, there is a call for more knowledge concerning how mHealth apps are used in practice.

Objective

This study aimed to review the literature on how usability is being addressed and measured in mHealth interventions for mental health problems.

Methods

We conducted a systematic literature review through a search for peer-reviewed studies published between 2001 and 2018 in the following electronic databases: EMBASE, CINAHL, PsycINFO, PubMed, and Web of Science. Two reviewers independently assessed all abstracts against the inclusion and exclusion criteria, following the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines.

Results

A total of 299 studies were initially identified based on the inclusion keywords. Following a review of the title, abstract, and full text, 42 studies were found that fulfilled the criteria, most of which evaluated usability with patients (n=29) and health care providers (n=11) as opposed to healthy users (n=8) and were directed at a wide variety of mental health problems (n=24). Half of the studies set out to evaluate usability (n=21), and the remainder focused on feasibility (n=10) or acceptability (n=10). Regarding the maturity of the evaluated systems, most were either prototypes or previously tested versions of the technology, and the studies included few accounts of sketching and participatory design processes. The most common reason referred to for developing mobile mental health apps was the availability of mobile devices to users, their popularity, and how people in general became accustomed to using them for various purposes.

Conclusions

This study provides a detailed account of how evidence of usability of mHealth apps is gathered in the form of usability evaluations from the perspective of computer science and human-computer interaction, including how users feature in the evaluation, how the study objectives and outcomes are stated, which research methods and techniques are used, and what the notion of mobility features is for mHealth apps. Most studies described their methods as trials, gathered data from a small sample size, and carried out a summative evaluation using a single questionnaire, which indicates that usability evaluation was not the main focus. As many studies described using an adapted version of a standard usability questionnaire, there may be a need for developing a standardized mHealth usability questionnaire.
Effectiveness of Smartphone App–Based Interactive Management on Glycemic Control in Chinese Patients With Poorly Controlled Diabetes: Randomized Controlled Trial
Authors: Zhang Lei , He Xingxing , Shen Yun , Yu Haoyong , Pan Jiemin , Zhu Wei , Zhou Jian , Bao Yuqian
Published: October 2019

Background

In recent years, the rapid development of mobile medical technology has provided multiple ways for the long-term management of chronic diseases, especially diabetes. As a new type of management model, smartphone apps are global, convenient, cheap, and interactive. Although apps were proved to be more effective at glycemic control, compared with traditional computer- and Web-based telemedicine technologies, how to gain a further and sustained improvement is still being explored.

Objective

The objective of this study was to investigate the effectiveness of an app-based interactive management model by a professional health care team on glycemic control in Chinese patients with poorly controlled diabetes.

Methods

This study was a 6-month long, single-center, prospective randomized controlled trial. A total of 276 type 1 or type 2 diabetes patients were enrolled and randomized to the control group (group A), app self-management group (group B), and app interactive management group (group C) in a 1:1:1 ratio. The primary outcome was the change in glycated hemoglobin (HbA1c) level. Missing data were handled by multiple imputation.

Results

At months 3 and 6, all 3 groups showed significant decreases in HbA1c levels (all P<.05). Patients in the app interactive management group had a significantly lower HbA1clevel than those in the app self-management group at 6 months (P=.04). The average HbA1c reduction in the app interactive management group was larger than that in the app self-management and control groups at both months 3 and 6 (all P<.05). However, no differences in HbA1c reduction were observed between the app self-management and control groups at both months 3 and 6 (both P>.05). Multivariate line regression analyses also showed that the app interactive management group was associated with the larger reduction of HbA1c compared with groups A and B at both months 3 and 6 (all P>.05). In addition, the app interactive management group had better control of triglyceride and high-density lipoprotein cholesterol levels at both months 3 and 6 compared with baseline (both P<.05).

Conclusions

In Chinese patients with poorly controlled diabetes, it was difficult to achieve long-term effective glucose improvement by using app self-management alone, but combining it with interactive management can help achieve rapid and sustained glycemic control.

Trial Registration

ClinicalTrials.gov NCT02589730; https://clinicaltrials.gov/ct2/show/NCT02589730.
Cost and Effectiveness of Using Facebook Advertising to Recruit Young Women for Research: PREFER (Contraceptive Preferences Study) Experience
Authors: McCarthy Edwina , Mazza Danielle
Published: October 2019

Background

Social media is a popular and convenient method for communicating on the Web. The most commonly used social networking website, Facebook, is increasingly being used as a tool for recruiting research participants because of its large user base and its ability to target advertisements on the basis of Facebook users’ information.

Objective

We evaluated the cost and effectiveness of using Facebook to recruit young women into a Web-based intervention study (PREFER). The PREFER study aimed to determine whether an educational video could increase preference for and uptake of long-acting reversible contraception (LARC).

Methods

We placed an advertisement on Facebook over a 19-day period from December 2017 to January 2018, inviting 16- to 25-year-old women from Australia to participate in a Web-based study about contraception. Those who clicked on the advertisement were directed to project information, and their eligibility was determined by using a screening survey.

Results

Our Facebook advertisement delivered 130,129 impressions, resulting in over 2000 clicks at an overall cost of Aus $918 (Aus $0.44 per click). Web-based project information was accessed by 493 women. Of these, 462 women completed the screening survey, and 437 (437/463, 95%) women were eligible. A total of 322 young women participated in Surveys 1 and 2 (74% response rate), and 284 women participated in Survey 3 (88% retention rate), with an advertising cost of Aus $2.85 per consenting participant.

Conclusions

Facebook proved to be a quick, effective, and cost-efficient tool for recruiting young Australian women into a study that was investigating contraceptive preferences. However, Web-based recruitment may result in sociodemographic biases. Further research is required to evaluate whether Facebook is suitable for recruiting older study populations.
Introducing Artificial Intelligence Training in Medical Education
Authors: Paranjape Ketan , Schinkel Michiel , Nannan Panday Rishi , Car Josip , Nanayakkara Prabath
Published: October 2019

Health care is evolving and with it the need to reform medical education. As the practice of medicine enters the age of artificial intelligence (AI), the use of data to improve clinical decision making will grow, pushing the need for skillful medicine-machine interaction. As the rate of medical knowledge grows, technologies such as AI are needed to enable health care professionals to effectively use this knowledge to practice medicine. Medical professionals need to be adequately trained in this new technology, its advantages to improve cost, quality, and access to health care, and its shortfalls such as transparency and liability. AI needs to be seamlessly integrated across different aspects of the curriculum. In this paper, we have addressed the state of medical education at present and have recommended a framework on how to evolve the medical education curriculum to include AI.
Which Physicians Attract Payment? Mining Massive Platform Data to Understand Patient Payment in Online Medical Consultation (Preprint)
Authors: Jiang Jinglu , Cameron Ann-Frances , Yang Ming
Published: October 2019

BACKGROUND

Online healthcare consultation has become increasingly popular, and is considered a potential solution to healthcare resource shortages and inefficient resource distribution. However, many online medical consultation platforms are struggling to attract and retain patients who are willing to pay, and healthcare providers on the platform have the additional challenge of standing out in a crowd of physicians who can provide comparable services.

OBJECTIVE

This study uses machine learning (ML) approaches to mine massive service data to (1) identify the important features that are associated with patient payment, as opposed to free-trial-only appointments; (2) explore the relative importance of these features, and (3) understand how these features interact, linearly or non-linearly, in relation to payment.

METHODS

The dataset is from the largest China-based online medical consultation platform, which covers 1,582,564 consultation records between patient-physician pairs from 2009 to 2018. ML techniques (i.e., hyperparameter tuning, model training, and validation) were applied with four classifiers – logistic regression, decision tree, random forest and gradient boost – to identify the most important features and their relative importance for predicting paid versus free-only appointments.

RESULTS

After applying the ML feature selection procedures, we identified 11 key features on the platform that are potentially useful to predict payment. For the binary ML classification task (paid vs. free services), the 11 features as a whole system achieved very good prediction performance across all four classifiers. Decision tree analysis further identified five distinct subgroups of patients delineated by five top ranked features: previous offline connection, total dialogue, physician response rate, patient privacy concern, and social return. These subgroups interact with the physician differently, resulting in different payment outcomes.

CONCLUSIONS

The results show that, as compared to features related to physician reputation, service-related features such as service delivery quality (e.g., consultation dialogue intensity, physician response rate), patient source (e.g., online versus offline returning patients) and patient involvement (e.g., provide social returns, reveal previous treatment) appear to contribute more to patient’s payment decision. Promoting multiple timely responses in patient-provider interactions is essential to encourage payment.
Aspectos estructurales y funcionales de la N-Succinil-L, L-diaminopimelato desuccinilasa, una enzima clave para el crecimiento bacteriano y un blanco para el control antimicrobiano
Authors: Díaz-Sánchez Ángel Gabriel , Terrazas-López Manuel , Aguirre-Reyes Luis Guadalupe , Lobo-Galo Naú , Álvarez-Parrilla Emilio , Martínez-Martínez Alejandro
Published: October 2019

La N-Succinil-L, L-diaminopimelato desuccinilasa (DapE) es una amidohidrolasa dependiente de iones de zinc, homodimérica estricta, que cataliza la descomposición del N-succinil-L, L-2,6-diaminopimelato (NSDAP), en succinato y diaminopimelato (DAP). Reacción que constituye la única fuente de meso-diaminopimelato (mDAP) y L-Lys en la mayoría de las bacterias. DapE es esencial para el crecimiento bacteriano y un blanco farmacológico antimicrobiano. El desarrollo de los inhibidores anti-DapE debe tener en cuenta las propiedades dinámicas de la enzima. Se buscan compuestos que interfieran con la formación del agujero del oxianión, en donde participan grupos de ambas subunidades del dímero, que se acomoda en posición catalítica mediante el cambio conformacional de la enzima de un estado abierto a uno cerrado, después de la unión del sustrato; estabilizando a los intermediarios de reacción y produciendo un descenso en la energía de activación. Con base en el análisis cristalográfico y el acoplamiento del sustrato en DapE que se presenta en este trabajo, se discute el papel de la flexibilidad conformacional de la enzima en la hidrólisis del sustrato. Se observa que tanto el grupo carbonilo del sustrato es susceptible al ataque como una molécula de agua ubicada en el sitio activo y se encuentran cercanos a la trayectoria de ataque, en el ángulo de Bürgi-Dunitz.
Association between maladaptive sleep hygiene behaviors and sleep quality in the general population
Authors: Sancho-Domingo Clara , Carballo José , Coloma-Carmona Ainhoa , Rodríguez-Marín Jesús
Published: October 2019

Prevalence of sleep problems has grown globally in recent years and sleep hygiene recommendations have shown inconsistent results. This study aims to analyze the quality of sleep in a non-clinical population and its association with maladaptive sleep hygiene. A total of 465 participants, with median age of 35 years (Interquartile range ? IQR = 28?44), completed the Sleep Hygiene Practices Scale (SHPS) and the Pittsburgh Sleep Quality Index (PSQI). Sample was divided into good quality sleepers (GQS; 52.7%, n = 245) and poor quality sleepers (PQS; 47.3%, n = 220). Comparison tests showed PQS had significant higher scores on SHPS (M = 61; IQR = 55?68, p < .01) compared with GQS (M = 68; IQR = 62?74). A logistic regression model indicated that only cognitive-arousal behaviors and inconsistent bedtimes were significant to classify poor sleep (R2 = .35; p < .01). In conclusion, poor sleep quality is common among healthy individuals and strongly associated with pre-sleep cognitive activity. This suggests that interventions aiming to improve sleep quality should consider strategies that would retract attention from concerns and worries at bedtime.