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Exploring van der Waals materials with high anisotropy:geometrical and optical approaches

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Light(Science & Applications) 2024年第4期13卷 645-653页

作者： aleksandr S.Slavich Georgy A.Ermolaev Mikhail K.Tatmyshevskiy Adilet N.Toksumakov Olga G.Matveeva Dmitriy V.Grudinin Kirill V.Voronin Arslan Mazitov Konstantin V.Kravtsov Alexander V.Syuy Dmitry M.Tsymbarenko Mikhail S.Mironov Sergey M.Novikov Ivan Kruglov Davit A.Ghazaryan Andrey A.Vyshnevyy Aleksey V.Arsenin Valentyn S.Volkov Kostya S.Novoselov Moscow Center for Advanced Studies Kulakova str.20Moscow 123592Russia. Emerging Technologies Research Center XPANCEOInternet CityEmmay TowerDubaiUnited Arab Emirates. Donostia International Physics Center(DIPC) Donostia/San-Sebastián 20018Spain. Institute of Materials Ecole Polytechnique Federale de Lausanne1015 LausanneSwitzerland. Department of Chemistry Lomonosov Moscow State UniversityMoscow 119991Russia. Laboratory of Advanced Functional Materials Yerevan State UniversityYerevan 0025Armenia. National Graphene Institute(NGI) University of ManchesterManchester M139PLUK. Department of Materials Science and Engineering National University of SingaporeSingapore 03-09 EASingapore. Institute for Functional Intelligent Materials National University of Singapore117544 SingaporeSingapore

The emergence of van der Waals(vdW)materials resulted in the discovery of their high optical,mechanical,and electronic anisotropic properties,immediately enabling countless novel phenomena and *** success inspired an intensive search for the highest possible anisotropic properties among vdW ***,the identification of the most promising among the huge family of vdW materials is a challenging quest requiring innovative ***,we suggest an easy-to-use method for such a survey based on the crystallographic geometrical perspective of vdW materials followed by their optical *** our approach,we found As2S3 as a highly anisotropic vdW *** demonstrates high in-plane optical anisotropy that is~20%larger than for rutile and over two times as large as calcite,high refractive index,and transparency in the visible range,overcoming the century-long record set by *** these benefits,As2S3 opens a pathway towards nextgeneration nanophotonics as demonstrated by an ultrathin true zero-order quarter-wave plate that combines classical and the Fabry–Pérot optical phase ***,our approach provides an effective and easy-to-use method to find vdW materials with the utmost anisotropic properties.

关键词： anisotropy anisotropic high

Changes in the growth of Scots pine(Pinus sylvestris L.)stands in an urban environment in European Russia since 1862

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林业研究:英文版 2023年第5期34卷 1279-1287页

作者： aleksandr V.Lebedev Department of Agricultural Meliorations Forestry and Land OrganizationRussian State Agrarian University-Moscow Timiryazev Agricultural AcademyTimiryazevskaya49MoscowRussia 127434

A century and a half ago,in the European part of Russia(Moscow),forest scientists established the first long-term observations of forests,many of which are under observation to the present *** the twentieth century,climate changes and,due to industrial development,forest areas were under air *** on observations from 157 sites,this study shows that the growth and density of Scots pine(Pinus sylvestris L.)have decreased by the end of the twentieth *** environment has changed,and the growth and development of plantations has *** yields(-34%stand volume)and their life expectancy(on average 50 years)have *** changes are critical for forestry and for the management of forests in urban *** to the decline in growth,ecosystem functions by urban forests has *** order to increase the sustainability of urban forests and the provision of ecosystem services,it is preferable to create multi-species stands with a complex structure.

关键词： Forest stand Scots pine Stand growth Urbanized environment Human footprint

Pulsed THz radiation under ultrafast optical discharge of vacuum photodiode

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Frontiers of Optoelectronics 2024年第2期 100-113页

作者： aleksandr A.Ushakov Kseniia A.Mamaeva Leonid V.Seleznev Georgy E.Rizaev Vladimir Bukin Timophey V.Dolmatov Pavel A.Chizhov Vladimir Bagdasarov Sergey V.Garnov Prokhorov General Physics Institute of the Russian Academy of Sciences Physical Institute Russian Academy of Sciences Moscow Institute of Physics and Technology Russian Institute for Scientific and Technical Information

In this paper, we first present an experimental demonstration of terahertz radiation pulse generation with energy up to 5 pJ under the electron emission during ultrafast optical discharge of a vacuum photodiode. We use a femtosecond optical excitation of metallic copper photocathode for the generation of ultrashort electron bunch and up to 45 kV/cm external electric field for the photo-emitted electron acceleration. Measurements of terahertz pulses energy as a function of emitted charge density, incidence angle of optical radiation and applied electric field have been provided. Spectral and polarization characteristics of generated terahertz pulses have also been studied. The proposed semi-analytical model and simulations in COMSOL Multiphysics prove the experimental data and allow for the optimization of experimental conditions aimed at flexible control of radiation parameters.

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Oscillations of an Inviscid Encapsulated Drop

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Fluid Dynamics & Materials Processing 2020年第4期16卷 761-771页

作者： aleksandr Shiryaev Ishlinsky Institute for Problems in Mechanics of the Russian Academy of Sciences Moscow119526Russia

The problem relating to the small-amplitude free capillary oscillations of an encapsulated spherical drop is solved theoretically in the framework of asymptotic *** are supposed to be inviscid and *** formulas derived are presented for different parameters of the inner and outer liquids,including densities,thickness of the outer liquid layer,and the surface and interfacial tension *** frequencies of oscillation of the encapsulated drop are studied in relation to several“modes”which can effectively be determined in experiments by photo and video *** results are presented in terms of oscillation frequencies reported as a function of the mode number,the spherical layer thickness and the relation between the(surface and interfacial)tension *** is revealed that the influence of the liquids’parameters(and related variations)on the drop oscillation changes dramatically depending on whether oscillations are“in-phase”or“out-of-phase”.Frequencies for“in-phase”type oscillations can be correlated with linear functions of the shell thickness and the relative values of interfacial tension coefficient whereas the analogous dependencies for the“out-of-phase”type oscillation are essentially non-linear.

关键词： Encapsulated drop oscillation frequencies inviscid fluid

Crystal structure and thermal expansion of perovskites containing uranium(VI) and rare-earth elements

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Journal of Rare Earths 2009年第1期27卷 4-11页

作者： aleksandr Knyazev Anna Ershova Nikolai Chernorukov Nizhny Novgorod State University

By the method of high-temperature reactions in solid phase, compounds with the general formula MⅡ（AⅢ2/3U1/3）O3（MⅡ=Sr, AⅢ=Sc, In;MⅡ=Ba, AⅢ=Sc, In, Y, Nd-Lu） were *** structures（space groups Fm 3 m and Pnma） were refined by the Rietveld method and morphotropic transition in Ba（Ln2/3U1/3）O3 on the border of Gd-Tb was *** means of high-temperature X-ray diffraction, phase transitions were studied and thermal expansion coefficients were determined.

关键词： perovskite uranium X-ray diffraction Rietveld structure thermal expansion rare earths

Photochemical degradation of nonylphenol in aqueous solution: The impact of pH and hydroxyl radical promoters

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Journal of Environmental Sciences 2013年第7期25卷 1326-1330页

作者： aleksandr Dulov Niina Dulova Marina Trapido Department of Chemical Engineering Tallinn University of Technology

The degradation of nonylphenol （NP） in aqueous solution with UV, H202/UV, and Fenton/photo-Fenton processes was studied. The efficacy of direct and hydrogen peroxide photolysis proved to be dependent on the pH value. The addition of H202 to UV treatment improved NP degradation. The application of UV photolysis and the H202/UV system at pH 7 resulted in low pseudo first-order rate constants at 104 sec1 . In the experiments at elevated pH values the pseudo-first order rate constants increased to 103 sec1 . The efficacy of the Fenton process was lower in comparison with UV and hydrogen peroxide photolysis. The addition of UV irradiation to the H202/Fe2＋ system substantially improved NP degradation efficacy. In terms of performance, the photo-Fenton process was similar to the H202/UV process. The most favourable process for complete nonylphenol degradation considering both operational cost and treatment efficacy was H202/UV at pH 11 and 250 μmol/L H202 .

关键词： AOPs endocrine disrupting compound photo-Fenton process photolysis UVC radiation

Utilization of Extrinsic Fabry-Perot Interferometers with Spectral Interferometric Interrogation for Microdisplacement Measurement

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Journal of Electronic Science and Technology 2020年第1期18卷 59-75页

作者： Leonid Liokumovich aleksandr Markvart Nikolai Ushakov Higher School of Applied Physics and Space Technologies Peter the Great St.Petersburg Polytechnic UniversitySt.Petersburg 195251

The paper presents a number of signal processing approaches for the spectral interferometric interrogation of extrinsic Fabry-Perot interferometers(EFPIs). The analysis of attainable microdisplacement resolution is performed and the analytical equations describing the dependence of resolution on parameters of the interrogation setup are derived. The efficiency of the proposed signal processing approaches and the validity of analytical derivations are supported by experiments. The proposed approaches allow the interrogation of up to four multiplexed sensors with attained resolution between 30 pm and 80 pm, up to three times improvement of microdisplacement resolution of a single sensor by means of using the reference interferometer and noisecompensating approach, and ability to register signals with frequencies up to 1 kHz in the case of 1 Hz spectrum acquisition rate. The proposed approaches can be used for various applications, including biomedical, industrial inspection, and others, amongst the microdisplacement measurement.

关键词： Absolute measurement dynamic measurement Fabry-Perot interferometer least-squares methods optical fiber sensors resolution analysis resolution enhancement sensor multiplexing spectral interferometry

Coronary revascularization in the elderly with stable angina

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Journal of Geriatric Cardiology 2015年第5期12卷 555-568页

作者： Kirill Lenarovich Kozlov aleksandr Andreevich Bogachev Laboratory of Age-Related Clinical Pathology Department of Clinical Gerontology and Geriatrics St. Petersburg Institute of Bioregulation and Gerontology Northwestern Branch Russian Academy of Medical Sciences Saint-Petersburg Russia Department of Cardiovascular Medicine Kirov Military Medical Academy Saint-Petersburg Russia

A proportion of elderly with coronary artery disease is rapidly growing. They have more severe coronary artery disease, therefore, derive more benefit fi＇om revascularization and have a greater need for it. The elderly is a heterogeneous group, but compared to the younger cohort, the choice of the optimal revascularization method is much more complicated among them. In recent decades, results has improved dramatically both in surgery and percutaneous coronary intervention （PCI）, even in very old persons. Despite the lack of evidence in elderly, it is obvious, that coronary artery bypass surgery （CABG） has a more pronounced effect on long-term survival in price of more strokes, while PCI is certainly less invasive. Age itself is not a criterion for the selection of treatment strategy, but the elderly are often more interested in quality of life and personal independence instead of longevity. This article discusses the factors that influence the choice of the revascularization method in the elderly with stable angina and presents a complex algorithm for making an individual risk-benefit profile. As a consequence the features of CABG and PCI in elderly patients are exposed. Emphasis is centered on the frailty and non-medical factors, including psychosocial, as essential components in making the decision of what strategy to choose. Good communication with the patients and giving them unbiased information is encouraged.

关键词： Angina Cardiopulmonary bypass Coronary artery disease Stents The elderly

Investigation of the parameters of spiral pattern in galaxies:the arm width

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Research in Astronomy and Astrophysics 2020年第8期20卷 177-180页

作者： aleksandr Mosenkov Sergey Savchenko Alexander Marchuk Department for Management of Science and Technology Development Ton Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Applied Sciences Ton Duc Thang UniversityHo Chi Minh CityVietnam Saint Petersburg State University Department of AstrophysicsSt.Petersburg198504 Russia Special Astrophysical Observatory Russian Academy of SciencesNizhnii Arkhyz369167 Russia

In this work,we determine the parameters of spiral structure for a sample of face-on spiral *** practice,the solution to this problem is a hard task because of the diversity of observed characteristics associated with spiral structure,such as the number of arms,their shape,arm contrast,*** study spiral structure in galaxies based on an analysis of photometric cuts perpendicular to the arm *** method is based on an approximation of these slices with an analytical function and derivation of the parameters of spiral structure(arm width,asymmetry,pitch angle)using the fitted parameters from this *** algorithm has been applied to a sample of 155 galaxies selected from the Sloan Digital Sky Survey in different *** this paper,we only consider the results on arm width:most spirals exhibit an increase in their width with galactocentric *** 14 per cent of galaxies in our sample show an opposite trend or have an almost constant arm width at all radii.

关键词： methods:data analysis techniques:photometric galaxies:structure