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Examination of inverse Hall-Petch relation in nanostructured aluminum alloys by ultra-severe plastic deformation

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Journal of Materials Science & Technology 2021年第32期91卷 78-89页

作者： Abbas Mohammadi Nariman A.Enikeev maxim Yumurashkin Makoto Arita Kaveh Edalati WPI International Institute for Carbon-Neutral Energy Research(WPI-I2CNER)Kyushu UniversityFukuoka 819-0395Japan Institute of Physics of Advanced Materials Ufa State Aviation Technical UniversityUfa 450008Russia Department of Materials Science and Engineering Faculty of EngineeringKyushu UniversityFukuoka 819-0395Japan International Joint Laboratory for Light Alloys(MOE) College of Materials Science and EngineeringChongqing UniversityChongqing400045China

To have an insight into the occurrence of inverse Hall-Petch relationship in ultrafine-grained(UFG) aluminum alloys produced by severe plastic deformation(SPD),ultra-SPD(*** several ten thousand shear strains via high-pressure torsion,HPT) followed by aging is applied to an Al-La-Ce *** nanograin sizes of 40 and 80 nm are successfully achieved together with strain-induced Lomer-Cottrell dislocation lock formation and aging-induced semi-coherent Al_(11)(La,Ce)_3 *** of hardening mechanisms in this alloy compared to SPD-processed pure aluminum with micrometer grain sizes,SPD-processed Al-based alloys with submicrometer grain sizes and ultra-SPD-processed Al-Ca alloy with nanograin sizes reveals the presence of two breaks in the Hall-Petch ***,a positive upbreak appears when the grain sizes decrease from micrometer to submicrometer which is due to extra hardening by solute-dislocation ***,a negative down-break and softening occur by decreasing the grain sizes from submicrometer to nanometer which is caused by weakening the dislocation hardening mechanism with minor contribution of the inverse Hall-Petch *** analyses confirm that nanograin formation is not necessarily a solution for extra hardening of Al-based alloys and other accompanying strategies such as grain-boundary segregation and precipitation are required to overcome such a down-break and softening.

关键词： Aluminum-lanthanum-cerium alloys Nanostructured alloys Reverse Hall-Petch relationship Precipitation hardening Dislocation hardening

Deformation defects and electron irradiation effect in nanostructured Al-Mg alloy processed by severe plastic deformation

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Transactions of Nonferrous Metals Society of China 2012年第8期22卷 1810-1816页

作者：刘满平孙少纯 Hans J.ROVEN 于瀛大张桢 maxim murashkin Ruslan Z.VALIEV 江苏大学材料科学与工程学院镇江212013 Department of Materials Science and Engineering Norwegian University of Science and Technology(NTNU)NO-7491TrondheimNorway Department of Materials Science and Engineering Norwegian University of Science and Technology(NTNU)NO-7491TrondheimNorway Institute of Physics of Advanced Materials Ufa State Aviation Technical UniversityUfa 450000Russia

In order to explore the exact nature of deformation defects previously observed in nanostructured Al-Mg alloys subjected to severe plastic deformation, a more thorough examination of the radiation effect on the formation of the planar defects in the high pressure torsion （HPT） alloys was conducted using high-resolution transmission electron microscopy （HRTEM）. The results show that high density defects in the HRTEM images disappear completely when these images are exposed under the electron beam for some duration of time. At the same time, lattice defects are never observed within no-defect areas even when the beam-exposure increases to the degree that holes appear in the areas. Therefore, it is confirmed that the planar defects observed in the HPT alloys mainly result from the significant plastic deformation and are not due to the radiation effect during HRTEM observation.

关键词： Al-Mg alloy severe plastic deformation high pressure torsion electron irradiation deformation defects transmission electron microscopy

On the primitive divisors of the recurrent sequence un＋1=(4cos^2(2π/7)-1)un-un-1 with applications to group theory

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Science China Mathematics 2018年第11期61卷 2101-2110页

作者： maxim Vsemirnov St. Petersburg Department of V.A. Steklov Institute of Mathematics St. Petersburg 191023 Russia Department of Mathematics and Mechanics St. Petersburg State University St. Petersburg 198504 Russia

Consider the sequence of algebraic integers un given by the starting values u0=0,u1=1 and the recurrence u_(n+1)=(4cos^2(2π/7)-1)u_n-u_(n-1).We prove that for any n ■{1,2,3,5,8,12,18,28,30}the n-th term of the sequence has a primitive divisor in Z[2 cos(2π/7)].As a consequence we deduce that for any sufficiently large n there exists a prime power q such that the groupcan be generated by a pair x,y with χ~2=y^3=(xy)~7=1 and the order of the commutator[x,y]is exactly *** latter result answers in affirmative a question of Holt and Plesken.

关键词： recurrent sequences primitive divisors Hurwitz groups

Efficient multi-response adaptive sampling algorithm for construction of variable-fidelity aerodynamic tables

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Chinese Journal of Aeronautics 2019年第3期32卷 547-558页

作者： maxim TYAN Jae-Woo LEE Department of Aerospace Information Engineering Konkuk University

Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-response adaptive sampling algorithm for simultaneous construction of multiple surrogate models in a time-efficient and accurate manner. The new algorithm uses the Jackknife cross-validation variance and a minimum distance metric to construct a sampling criterion function. A weighted sum of the function is used to consider the characteristics of multiple surrogate models. The proposed algorithm demonstrates good performance on total 22 numerical problems in comparison with three existing adaptive sampling algorithms. The numerical problems include several two-dimensional and six-dimensional functions which are combined into singleresponse and multi-response systems. Application of the proposed algorithm for construction of aerodynamic tables for 2 D airfoil is demonstrated. Scaling-based variable-fidelity modeling is implemented to enhance the accuracy of surrogate modeling. The algorithm succeeds in constructing a system of three highly nonlinear aerodynamic response surfaces within a reasonable amount of time while preserving high accuracy of approximation.

关键词： Adaptive sampling Aerodynamic database Multi-response system Surrogate modeling Variable fidelity modeling

Primordial black holes

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Research in Astronomy and Astrophysics 2010年第6期10卷 495-528页

作者： maxim Yu.Khlopov Centre for Cosmoparticle Physics "Cosmion " National Research Nuclear University "Moscow Engineering Physics Institute " APC laboratory 10

Primordial black holes （PBHs） are a profound signature of primordial cosmological structures and provide a theoretical tool to study nontrivial physics of the early Universe. The mechanisms of PBH formation are discussed and observational constraints on the PBH spectrum, or effects of PBH evaporation, are shown to restrict a wide range of particle physics models, predicting an enhancement of the ultraviolet part of the spectrum of density perturbations, early dust-like stages, first order phase transitions and stages of superheavy metastable particle dominance in the early Universe. The mechanism of closed wall contraction can lead, in the inflationary Universe, to a new approach to galaxy formation, involving primordial clouds of massive BHs created around the intermediate mass or supermassive BH and playing the role of galactic seeds.

关键词： cosmology: theory -- elementary particles -- black hole physics -- dark matter -- early universe

Roots of the taxonomic impediment:Is the“integrativeness”a remedy?

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Integrative Zoology 2020年第1期15卷 2-15页

作者： maxim V.VINARSKI Laboratory of Macroecology and Biogeography of Invertebrates Saint-Petersburg State UniversitySaint-PetersburgRussia

The use of the“integrative approach”for classification of organisms since its formal establishment in 2005 has become a recurrent theme of zoosystematics.A bibliometric survey of the publications on integrative taxonomy of animals,which is aimed at exploring the most popular areas of research and characterizing the practical systematists’attitudes to this new approach,is *** analysis of 582 papers,which appeared between 2005 and 2017 in journals indexed by Scopus and the Web of Science Core Collection,has illustrated the gradual growth of the popularity of integrative taxonomy as well as some biases in the representation of higher taxa in“integrated”*** has been shown that the“integrative”papers have more chance of appearing in a top-ranking journal and gain relatively more citations as compared with non-integrative *** obtained results are discussed in the context of the“taxonomic impediment”problem thought to be a consequence of the institutional crisis of traditional taxonomy,which has been vividly debated over the past decades.

关键词： animal systematics bibliometric analysis biodiversity crisis integrative taxonomy taxonomic impediment

Post-pancreatitis diabetes mellitus and excess intra-pancreatic fat deposition as harbingers of pancreatic cancer

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World Journal of Gastroenterology 2021年第17期27卷 1936-1942页

作者： maxim S Petrov School of Medicine The University of AucklandAuckland 1142New Zealand

Progress in the fight against pancreatic cancer has been hampered by many *** of them is the inability to detect the disease early in overwhelming majority of *** present paper outlines a novel way in which progress could be *** includes a focus on two harbingers—post-pancreatitis diabetes mellitus and excess intra-pancreatic fat deposition—that converge at affecting the tumor macroenvironment and microenvironment specifically in the pancreas,not other *** two entities have the potential to be incorporated into future screening strategies with a view to early detecting of pancreatic cancer.

关键词： Pancreatic cancer Post-pancreatitis diabetes mellitus Intra-pancreatic fat Pancreatitis Early detection Screening

Transverse magnetoresistance peculiarities of thermoelectric Lu-doped Bi_2Te_3 compound due to strong electrical disorder

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Journal of Rare Earths 2019年第3期37卷 292-298页

作者： Oleg Ivanov maxim Yaprintsev Elena Danshina Belgorod State University Belgorod State Technological University named after V.G.Shukhov

The n-type thermoelectric Bi_(1.9)Lu_(0.1)Te_3 was prepared by microwave-solvothermal method and spark plasma sintering. The magnetic field and temperature dependences of transverse magneto resistance measured within temperature 2-200 K interval allow finding the peculiarities characteristic for strongly disordered and inhomogeneous semiconductors. The first peculiarity is due to appearance of linear-inmagnetic field contribution to the total magneto resistance reflected in a crossover from quadratic magnetoresistance at low magnetic fields to linear magneto resistance at high magnetic fields. The linear magnetoresistance can result from the Hall resistance picked up from macroscopically distorted current paths due to local variations in stoichiometry of the compound studied. The second peculiarity is that both linear magnetoresistance magnitude and crossover field are functions of carrier mobility which is in agreement with the Parish and Littlewood model developed for disordered and inhomogeneous semiconductors. An increase in the mobility due to a decrease in temperature is accompanied by an increase in the magnetoresistance magnitude and a decrease in the crossover field. Finally, the third peculiarity is related to the remarkable deviation of the total magnetoresistance measured at various temperatures from the Kohler's rule. Presence of strong inhomogeneity and disorder in the Bi_(1.9)Lu_(0.1)Te_3 structure concluded from the magnetoresistance peculiarities can be responsible for the remarkable reduction in the total thermal conductivity of this compound.

关键词： Bismuth telluride Linear positive magnetoresistance Semiconductors Thermoelectric material Carrier mobility Kohler’s rule

Comparative equilibrium studies of sorption of Pb(Ⅱ) ions by sodium and calcium alginate

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Journal of Environmental Sciences 2008年第7期20卷 827-831页

作者： KHOTIMCHENKO maxim KOVALEV Valeri KHOTIMCHENKO Yuri Department of pharmacy Vladivostok State Medical UniversityVladivostok 690990Russia Laboratory of Pharmacology Institute of Marine BiologyFar East Branch of Russian Academy of SciencesVladivostok 690041Russia. Laboratory of Pharmacology Institute of Marine BiologyFar East Branch of Russian Academy of SciencesVladivostok 690041Russia.Department of pharmacyVladivostok State Medical UniversityVladivostok 690990Russia

The absorption of Pb(Ⅱ) ions from aqueous solution by different alginate compounds was studied in a batch sorption *** soluble sodium alginate and insoluble calcium alginate beads were *** lead-binding capacity of both alginate compounds was highest within the pH range *** binding capacities and rates of Pb(lI) ions by alginate compounds were *** Langmuir,Freundlich,and Bruneaur,Emmet and Teller (BET) sorption models were applied to describe the isotherms and isotherm con...

关键词： heavy metal lead equilibrium study alginate wastewater