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Impact of doping profiles on the formation of laser-active centers in bismuth-doped GeO_(2)–SiO_(2)glass fibers

Photonics Research 2024年第2期12卷 260-270页

作者： SERGEY ALYSHEV ALEXANDER VAKHRUSHEV ALEKSANDR KHEGAI ELENA FIRSTOVA KONSTANTIN RIUMKIN MIKHAIL MELKUMOV LYUDMILA ISKHAKOVA ANDREY UMNIKOV SERGEI FIRSTOV Prokhorov General Physics Institute of the russian Academy of sciences Dianov Fiber Optics Research Center119333 MoscowRussia Devyatykh Institute of Chemistry of High-Purity Substances of the russian Academy of sciences 603951 Nizhny NovgorodRussia

Multi-wavelength-band transmission technology based on the exploitation of the extended spectral region is considered as a potential approach to increase the transmission capacity in the deployed fiber-optic communication *** development of optical amplifiers operating in the O-,E-,S-,and U-telecom bands is an extremely important challenge for the successful implementation of this ***-doped fibers are of increasing interest as gain materials,which can be used to provide broadband amplification in the mentioned telecom *** is due to the ability of Bi ions incorporated into glass network to form bismuth active centers(BACs)with specific optical properties,which are primarily determined by the glass *** this work,the impact of the doping profiles of both Ge atoms as glass modifiers and Bi ions on the BACs formation is studied using a series of bismuth-doped fibers fabricated by the modified chemical vapor deposition(MCVD)*** Bi-to-BACs conversion efficiency in various spatial regions of the studied samples is *** is turned out that for high-Bi concentration regions,the conversion efficiency is very low(less than 10%).In addition,the relationship of the conversion efficiency to the distribution of Bi ions and/or Ge atoms is ***,a continuous-wave laser at 1.46μm with a record slope efficiency of 80%is demonstrated using a Bi-doped fiber with confined doping profile,where the Bi-to-BACs conversion efficiency is 35%.This paper provides new information which might help to facilitate understanding of the features of Bi-doped fibers and their potentially achievable characteristics.

关键词： fiber fibers bismuth

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Wood anatomy chronologies of Scots pine in the foothills of the Western Sayan(Siberia)

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Journal of Forestry Research 2024年第3期35卷 13-27页

作者： Elena A.Babushkina Dmitry R.Dergunov Mikhail S.Zharkov Liliana V.Belokopytova Dina F.Zhirnova Bao Yang Jingjing Liu Xiaomei Peng Eugene A.Vaganov Khakass Technical Institute Siberian Federal UniversityAbakan 655017Russia Institute of Ecology and Geography Siberian Federal UniversityKrasnoyarsk 660036Russia Mathematical Methods and IT Department Siberian Federal UniversityKrasnoyarsk 660036Russia Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000People's Republic of China School of Geographic and Oceanographic sciences Nanjing UniversityNanjing 210093People's Republic of China Department of Dendroecology V.N.Sukachev Institute of ForestSiberian Branch of the Russian Academy of ScienceKrasnoyarsk 660036Russia

Recent methodological advances in quantitative wood anatomy have provided new insights into the climatic responses of radial growth at the scale of cell structure of tree rings. This study considered long-term chronologies of tracheid measurements, indexed by a novel approach to separate their specific climatic responses from signal recorded in cell production(closely reflected in tree-ring width). To fill gaps in understanding the impact of climate on conifer xylem structure, Scots pine(Pinus sylvestris L.)trees > 200 years old were selected within the forest-steppe zone in southern Siberia. Such habitats undergo mild moisture deficits and the resulting climatic regulation of growth processes. Mean and maximum values of cell radial diameter and cell wall thickness were recorded for each tree *** a low level of climatogenic stress, components of cell chronologies independent of cambial activity were separated to obtain significant climatic signals revealing the timing of the specific stages of tracheid differentiation. Cell expansion lasted from mid-April to July and was impacted similarly to tree-ring width(stimulated by precipitation and stressed by heat), maximum cell size formed late June. A switch in the climatic responses of mean anatomical traits indicated transition to latewood in mid-July. Secondary wall deposition lasted until mid-September, suppressed by end of season temperatures. Generally, anatomical climatic responses were modulated by a less dry May and September compared with summer months.

关键词： Quantitative wood anatomy Cell radial size Cell wall thickness Pinus sylvestris Climatic response

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Efficient cold atom source from a single-layer atom chip

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Chinese Optics Letters 2024年第6期22卷 108-113页

作者： Petr Skakunenko Darya Bykova Anton Afanasiev Alexey Kalmykov Roman Kirtaev Victor Balykin Institute of Spectroscopy russian Academy of sciences Moscow Institute of Physics and Technology Skolkovo Institute of science and Technology National Research University Higher School of Economics Emerging Technologies Research Center XPANCEO

We developed a new single-layer atom chip with an additional U-shaped current-carrying *** new U-shaped microwire creates optimized magnetic field distribution,which increases the trapping volume of a magneto-optical trap（MOT） near the *** approach allows one to localize more atoms,while a setup remains relatively simple （single-layer approach） and consumes low current （up to 10 A）. The total number of trapped87Rb atoms in our setup is 5×10～7.

关键词： Bose Einstein condensates Laser beams Laser cooling Optical clocks Quantum noise Rubidium

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Predicting impact strength of perforated targets using artificial neural networks trained on FEM-generated datasets

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Defence Technology（防务技术） 2024年第2期32卷 32-44页

作者： Nikita Kazarinov Aleksandr Khvorov Saint Petersburg State University Saint Petersburg 199034Russia Higher School of Economics Saint Petersburg 190121Russia

The paper considers application of artificial neural networks(ANNs)for fast numerical evaluation of a residual impactor velocity for a family of perforated PMMA(Polymethylmethacrylate)*** ANN models were trained using sets of numerical results on impact of PMMA plates obtained via dynamic FEM coupled with incubation time fracture *** developed approach makes it possible to evaluate the impact strength of a particular target configuration without complicated FEM calculations which require considerable computational ***,it is shown that the ANN models are able to predict results for the configurations which cannot be processed using the developed FEM routine due to numerical instabilities and errors:the trained neural network uses information from successful computations to obtain results for the problematic cases.A simple static problem of a perforated plate deformation is discussed prior to the impact problem and preferable ANN architectures are presented for both *** insight into the perforation pattern optimization using a genetic algorithm coupled with the ANN is also made and optimized perforation patterns which theoretically enhance the target impact strength are constructed.

关键词： Machine learning Impact Dynamic fracture FEM Mesh distortion Optimization

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Analysis of the discrete contact characteristics based on the Greenwood-Williamson model and the localization principle

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Friction 2024年第5期12卷 1042-1056页

作者： Anastasiya A.YAKOVENKO Irina G.GORYACHEVA Ishlinsky Institute for Problems in Mechanics RAS Moscow119526Russia

The contact of a rigid body with nominally flat rough surface and an elastic half-space is *** solve the contact problem,the Greenwood-Williamson statistical model and the localization principle are *** developed contact model allows us to investigate the surface approach and the real contact area with taking into account the asperities *** is shown that the mutual influence of asperities changes not only contact characteristics at the macroscale,but also the contact pressure distribution at the *** follows from the results,the inclusion in the contact model of the effect of the mutual influence of asperities is especially significant for studying the real contact area,as well as the contact characteristics at high applied *** results calculated according to the proposed approach are in a good agreement with the experimentally observed effects,i.e.,the real contact area saturation and the additional compliance exhaustion.

关键词： surface roughness elasticity Greenwood-Williamson model localization principle asperity interaction

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Thermo-and pH-sensitive Polymer with Pendant Spacer-linked Imidazole Cycles

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Chinese Journal of Polymer science 2024年第4期42卷 437-445页

作者： Natalya V.Zakharova Stanislav N.Zelinskiy Mariya S.Strelova Elena N.Danilovtseva Vadim V.Annenkov Institute of Macromolecular Compounds of the russian Academy of sciences Saint Petersburg199004Russia Limnological Institute of Siberian Branch of the russian Academy of sciences Irkutsk664033Russia

By the reaction of poly(acryloyl chloride) with N-(3-aminopropyl)imidazole, poly(N-(3-(1H-imidazol-1-yl)propyl)acrylamide) was synthesized. The new polymer contains an imidazole ring removed from the main chain by a spacer of five bonds. The structure and purity, molecular weight, hydrodynamic and thermosensitive properties of the obtained sample were studied by1H-and13C-NMR, FTIR spectroscopy, acid-base titration, light scattering, turbidimetry and viscometry. The observed ability of the imidazole-containing polymer to form and destroy associates in water-salt solutions at pH 6.6-7.4 and temperatures of 29-48℃ indicates that these are promising candidates for designing complex biomedical systems. The new polymer is able to form complexes with oligo-DNA more actively than poly(1-vinylimidazole), which is of interest for gene delivery applications. The polymer cross-linked with epichlorohydrin gives micro-relief coatings on the plastic surface, and the modified surface is able to attach negatively charged objects. This thermo-and pH-sensitive polymer modification can be applied to create finely controlled surfaces for cell culturing.

关键词： Imidazole-containing polymer Thermolability pH-sensitivity The modified surface DNA immobilization

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Polyelectrolyte Complexes between Hyperbranched and Linear Polysaccharides: Fucoidan/Chitosan

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Chinese Journal of Polymer science 2024年第4期42卷 468-479页

作者： Ekaterina R.Gasilova Daria N.Poshina Aleksandra O.Sitnikova Natalia N.Saprykina Yury A.Skorik Institute of Macromolecular Compounds of the russian Academy of sciences Bolshoi VO 31St.Petersburg199004Russian Federation

Polyelectrolyte complexes(PECs)of hyperbranched(HB)and linear polysaccharides are promising as more effective encapsulation agents compared to PECs formed by linear *** investigated the PECs between the HB anionic polysaccharide fucoidan(FUC)and the cationic linear polysaccharide chitosan(CS).The FUC had a molecular weight(MW)of 30×*** PECs were prepared in three solvents(water,0.01 and 0.1 mol/L acetic acid)with CS of MW of 15,110 and 170 kDa,and deacetylation degrees(DDA)of 70%and 97%.The structures of the PECs and the initial FUC were investigated by multi-angle static and dynamic light *** the FUC contained 18 wt%of—OSO3 groups and 5 wt%of uronic acid units,it was a“strong-weak”copolyanion,so the HB macromolecules of the FUC formed nanogel particles in 0.1 mol/L AcOH and open branched structures in water,as confirmed by the Kratky *** mixing the solutions of original components,the PEC structures underwent an equilibration period,the duration of which increased with the MW of *** the charge stoichiometry was approached,the PECs shrank;the fractal dimension approached unity,indicating the side-by-side packing of adjacent FUC branches with the help of *** aggregation in the vicinity of the charge compensation was hardly observed,as it occurred in a very narrow *** PEC content at theζ-potential inversion depended on solvents’pH and the DDA of *** the extreme case of core-shell PECs in 0.1 mol/L AcOH,obtained by mixing FUC nanogels with the solutions of high MW CS of 97%DDA,the protruding tails of CS formed a positively charged shell in the whole range of FUC content(10 wt%

关键词： Polyelectrolyte complexes Chitosan Hyperbranched fucoidan Light scattering

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Model of fractured medium and nondestructive control of composite materials

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Chinese Journal of Aeronautics 2024年第2期37卷 93-99页

作者： Vasily GOLUBEV Ilia NIKITIN Katerina BEKLEMYSHEVA Department of Computers science and Numerical Mathematics Moscow Institute of Physics and TechnologyDolgoprudny 141700Russia Mathematical Modeling and Management Department of InformatizationInstitute of Computer Aided Design RASMoscow 123056Russia

Non-destructive testing of composites is an important issue in the modern aircraft *** are susceptible to the barely visible impact damage which can affect the residual strength of the material and occurs both during production and *** continuum model for describing the damaged zone is *** slip theory relations used for a continuous distribution of slip planes are *** the initial stage,the isotropic background model is *** model allows the material slippage along the fractures based on the Coulomb friction law with the small viscous *** this regime,the govern system of equations becomes *** overcome this difficulty,the explicit-implicit grid-characteristic scheme is *** standard ultrasound diagnostic procedure of damaged composite materials is successfully *** with the trivial free-surface fracture model,different reactions on the compression and stretch waves are *** approach provided an effective way for the simulation of complex dynamic behavior of damage zones.

关键词： Non-destructive testing Composite materials Numerical modeling Continuum model Grid-characteristic method

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Strong Subgame Consistency of the Core in Stochastic Network Formation Games

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Journal of the Operations Research Society of China 2024年第1期12卷 189-213页

作者： Ping Sun Elena Parilina Faculty of Applied Mathematics and Control Processes Saint Petersburg State UniversitySaint Petersburg199034Russia

We consider a model of network formation as a stochastic game with random duration proposed initially in Sun and Parilina(Autom Remote Control 82(6):1065–1082,2021).In the model,the leader first suggests a joint project to other players,i.e.,the network connecting ***,the players are allowed to form fresh links with each other updating the initially proposed *** stage payoff of any player is defined depending on the network *** are two types of randomness in the network formation process:(i)links may fail to be formed with different probabilities although players intend to establish them,(ii)the game process may terminate at any stage or transit to the next stage with a certain probability ***,a network is formed as a result of players’decisions and realization of random *** cooperative version of the stochastic game is *** particular,we examine the properties of subgame consistency as well as strong subgame consistency of the *** provide a payment mechanism or regularization of the core elements to sustain its subgame consistency and avoid the player’s deviations from the cooperative *** addition,the distribution procedure of the core elements is regularized in case there are negative payments to achieve only nonnegative payments to the players at any *** sufficient condition of a strongly subgame consistent core is also *** illustrate our theoretical results with a numerical example.

关键词： Stochastic game Network formation Core Strong subgame consistency

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Nanomotion of bacteria to determine metabolic profile

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Nanotechnology and Precision Engineering 2024年第1期7卷 1-9页

作者： S.N.Pleskova E.V.Lazarenko N.A.Bezrukov R.N.Kriukov A.V.Boryakov M.E.Dokukin S.I.Surodin Research Laboratory of Scanning Probe Microscopy Lobachevsky State University of Nizhny NovgorodNizhny Novgorod 603950Russia Department of Nanotechnology and Biotechnology Nizhny Novgorod State Technical University n.a.R.E.AlekseevNizhny Novgorod 603950Russia Sarov Physics and Technology Institute National Research Nuclear University MEPhISarov 607186Russia

In addition to their visible motion such as swimming(e.g.,with the help ofﬂagella),bacteria can also exhibit nanomotion that is detectable only with highly sensitive instruments,and this study shows that it is possible to detect bacterial nanomotion using an AFM detection *** results show that the nanomotion characteristics depend on the bacterial strain,and that nanomotion can be used to sense the metabolic activity of bacteria because the oscillations are sensitive to the food preferences of the bacteria and the type of surrounding medium.

关键词： Nanomotion Bacteria Cantilever Oscillation Atomic force microscopy Metabolism

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