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Resolution and contrast enhancement of laser-scanning multiphoton microscopy using thulium-doped upconversion nanoparticles

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Nano research 2019年第12期12卷 2933-2940页

作者： Alexey B.Kostyuk Artem D.Vorotnov Andrey V.Ivanov Arthur B.Volovetskiy Aleksandr V.Kruglov Lyudmila M.Sencha Liuen Liang Evgenii L.Guryev Vladimir A.Vodeneev Sergey M.Deyev Yiqing Lu Andrei V.Zvyagin Lobachevsky State University of Nizhny Novgorod Nizhny Novgorod 603950Russia Center of Biomedical Engineering Institute of Molecular MedicineSechenov UniversityMoscow 119991Russia ARC Centre of Excellence"Nanoscale BioPhotonics" Department of Physics and AstronomyMacquarie UniversitySydney 2109Australia Institute ofBioorganic Chemistry Russian Academy of SciencesMoscow 117997Russia

High-contrast optical imagi ng is achievable using phosphoresce nt labels to suppress the short-lived background due to the optical backscatterand autofluoresce ***,the long-lived phosphorescence is generally incompatible with high-speed laser-scan ning imaging ***,we show that upc on versi on nan oparticles of structure NaYF4:Yb co-doped with 8%Tm(8T-UCNP)in combi nation with a commerciallaser-scanning multiphoton microscopy are uniquely suited for labeling biological systems to acquire high-resolution images with the enhancedcon *** comparison with many phosphoresce nt labels,the 8T-UCNP emission lifetime of-15μs affords rapid image ***-order optical nonlinearity of the 8T-UCNP(n=4,as confirmed experimentally and theoretically)afforded pushing the resolution limitattain able with UCNPs to the *** contrast enha nceme nt was achieved by suppressing the backgro und using(i)ban dpassspectral filtering of the narrow emission peak of 8T-UCNP at 455-nm,and(ii)time-gating implemented with a time-correlated single-photon counting system that demonstrated the contrast enhancement of>2.5-fold of polyethyle neimine-coated 8T-UCNPs take n up by huma nbreast adeno carcinoma cells *** a result,discrete 8T-UCNP nan oparticles became clearly observable in the freshly excised splee ntissue of laboratory mice 15-min post in trave nous injectio n of an 8T-UCNP *** dem on strated approach paves the way forhigh-contrast,high-resoluti on,and high-speed multiphot on microscopy in challe nging envir onments of i ntense autofluorescence,exogenous staining,and turbidity,as typically occur in intravital imaging.

关键词： upconversion nanoparticles autofluorescence time-gated imaging scanning microscopy time-correlated single photon counting

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Theoretical search for solutions to minimize negative influence of segregation in mixing of particulate solids

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Particuology 2016年第2期14卷 36-41页

作者： Vadim Mizonova Henri Berthiaux Cendrine Gatumel Department of Applied Mathematics lvonovo State Power Engineering University Rabfakovskaya 34 153003 Ivanovo Russia Centre RAPSODEE UMR CNR5 5302 Ecole des Mines d'Albi-Carmaux CampusJarlard route de Teillet 81000 Albi France

The objective of this study is to examine several optimization problems in the batch mixing of segregating particulate solids that can be set up and solved using Markov chain models. To improve the adequacy of such models and exclude some physical contradictions that arise in the linear form, a non-linear Markov chain model for the mixing of segregating components is proposed. Optimal solutions are obtained by controlling the particle flow outside the mixing operating volume while the components are being loaded, modifying particle circulation inside the mixing zone during the process, and by structuring the load in the mixing zone. Solutions are found that not only reduce the negative influence of segregation, but also exclude it altogether. The gain resulting from optimization grows with the rate of segregation. The optimal solutions presented here can be used to improve the design of mixers.

关键词： Mixing Segregation Mixture quality Markov chain Optimization

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A Markov chain model of mixing kinetics for ternary mixture of dissimilar particulate solids

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Particuology 2017年第2期15卷 80-86页

作者： Vadim Mizonov Ivan Balagurov Henri Berthiaux Cendrine Gatumel Department of Applied Mathematics Ivanovo State Power Engineering University Russia Centre RAPSODEE UMR CNRS 5302 Ecole des Mines d'Albi-Carmaux Campus Jarlard Route de Teillet 81000 Alhi France

This paper presents a simple but informative mathematical model to describe the mixing of three dissimilar components of particulate solids that have the tendency to segregate within one another. A nonlinear Markov chain model is proposed to describe the process. At each time step, the exchange of particulate solids between the cells of the chain is divided into two virtual stages. The first is pure stochastic mixing accompanied by downward segregation. Upon the completion of this stage, some of the cells appear to be overfilled with the mixture, while others appear to have a void space. The second stage is related to upward segregation. Components from the overfilled cells fill the upper cells （those with the void space） according to the proposed algorithm. The degree of non-homogeneity in the mixture （the standard deviation） is calculated at each time step, which allows the mixing kinetics to be described. The optimum mixing time is found to provide the maximum homogeneity in the ternary mixture. However, this “common” time differs from the optimum mixing times for individual components. The model is verified using a lab-scale vibration vessel, and a reasonable correlation between the calculated and experimental data is obtained

关键词： Ternary mixture Segregation Mixing kinetics Markov chain Matrix of transition probabilities Optimum mixing time

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Boosting the superconducting spin valve effect in a metallic superconductor/ferromagnet heterostructure

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Nano research 2016年第4期9卷 1005-1011页

作者： Pavel V. Leksin Andrey A. Kamashev Joachim Schumann Vladislav E. Kataev Jurgen Thomas Bernd Buchner Ilgiz A. Garifullin Leibniz Institute for Solid State and Materials research Dresden (IFW Dresden) DoO 1171 Dresden Germany Zavoisky Physical-Technical Institute Russian Academy of Sciences 420029 Kazan Russia Dresden University of Technology D-01062 Dresden Germany

Superconducting spin valves based on the superconductor/ferromagnet （S/F） proximity effect are considered to be a key element in the emerging field of superconducting spintronics. Here, we demonstrate the crucial role of the morphology of the superconducting layer in the operation of a multilayer S/F1/F2 spin valve. We study two types of superconducting spin valve heterostructures, with rough and with smooth superconducting layers, using transmission electron microscopy in combination with transport and magnetic characterization. We find that the quality of the S/F interface is not critical for the S/F proximity effect, as regards the suppression of the critical temperature of the S layer. However, it appears to be of paramount importance in the performance of the S/F1/F2 spin valve. As the morphology of the S layer changes from the form of overlapping islands to a smooth case, the magnitude of the conventional superconducting spin valve effect significantly increases. We attribute this dramatic effect to a homogenization of the Green function of the superconducting condensate over the S/F interface in the S/F1/F2 valve with a smooth surface of the S laver.

关键词： spintronics superconductivi ferromagnetism proximity effect

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SERS-based lateral flow immunoassay of troponin I by using gapenhanced Raman tags

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Nano research 2019年第2期12卷 413-420页

作者： Boris N. Khlebtsov Daniil N. Bratashov Nadezhda A. Byzova Boris B. Dzantiev Nikolai G. Khlebtsov Institute of Biochemistry and Physiology of Plants and Microorganisms Russian Academy of Sciences Saratov 410049 Russia Saratov State University Saratov 410012 Russia A. N. Bach Institute of Biochemistry Research Centre of Biotechnology Russian Academy of Sciences Moscow 119071 Russia

The lateral flow immuno assay (LFIA) has emerged as a powerful tool for rapid scree ning owing to its simplicity and flexibility for detection of various biomarkers. However, conventional LFIA strips have several disadvantages, including limits in quantitative analysis and low sensitivity. Here we developed a novel surface-e nhanced Rama n scatteri ng LFIA based on non spherical gap-e nhanced Raman tags (GERTs), with Raman molecules (RMs) embedded in a 1-nm gap between Au nanorod core and Au shell. Such tags have a strong and uniform surface-enhanced Rama n scattering (SERS) resp on se, an order of mag nitude higher than that of other comm on SERS tags such as Au nano rods, nano stars, Au nano shells with surface-adsorbed RMs, or spherical GERTs with embedded RMs. The feasibility of the tags was dem on strated by the semiqua ntitative and sen sitive detecti on of the heart disease biomarker cardiac tropo nin I (cTnI). GERTs were conjugated with mono clonal antibodies and used for LFIA in the same way as ordinary functionalized colloidal gold. The presenee of the target antigen, cTnI, was identified by Raman microscopy mapping of the test zone. With the SERS-based LFIA, the limit of cTnI detection was about 0.1 ng/mL. This value is within the diagnostic range of cTnI in the blood serum of patients with heart infarction and is 30 times lower than that of the colorimetric LFIA test using the same antibodies and either GERTs or colloidal gold as labels.

关键词： surface-enhanced Raman scattering (SERS) lateral flow immunoassay Au core/shell nanorods gap-enhanced Raman tags cardiac troponin I

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Model of homogenisation for analysing the effect of micrometre pore sizes on the elastic moduli of porous materials

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Acta Mechanica Sinica 2019年第5期35卷 1060-1066页

作者： A.F.Fedotov Department of Mechanics Samara State Technical UniversitySamara 443100Russian Federation

A homogenisation model for analysing the effect of micrometre pore sizes on the engineering moduli of elasticity of porous materials was *** the proposed model,the engineering coefficients of localization of total strains(LTS coefficients)are considered instead of the classical strain localization *** a pore,these coefficients represent the ratio of the sum of the strains in the volume of the pore to the sum of the strains in the volume of the porous *** estimate the elastic moduli of a material with an arbitrary pore size,it is sufficient to have information about the elastic moduli and the LTS coefficient of a material with one basic pore ***,in Eshelby's model of equivalent inclusion,a transition to LTS coefficient for material with arbitrary pore size is achieved,and its elasticity moduli are *** results for Young's modulus of porous titanium,with different sizes of spherical pores,completely conform with the experimental *** have obtained a model theoretic estimate of the upper bounds of Young's modulus of porous materials with infinitely small pore *** the spherical pores,the proposed assessment coincides with the upper limits of the Hashin-Shtrikman bounds.

关键词： Elastic moduli Porous material Pore sizes

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Sociability and pair-bonding in gerbils: a comparative experimental study

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Current Zoology 2019年第4期65卷 363-373页

作者： Andrey V. TCHABOVSKY Ludmila E. SAVINETSKAYA Natalia L. OVCHINNIKOVA Alexandra SAFONOVA Olga N. ILCHENKO Svetlana R. SAPOZHNIKOVA Nina A. VASILIEVA Department of Vertebrate Zoology A.N. Severtsov Institute of Ecology and Evolution Moscow Russia Laboratory for Population Ecology Lomonosov Moscow State University Russia Moscow Zoo Russia

In a study of gerbils with contrasting social and mating systems (group-living monogamous Mongolian gerbil Meriones unguiculatus, solitary nonterritorial promiscuous midday jird M. meridianus, and solitary territorial promiscuous pale gerbil Gerbillus perpallidus), we employed part ner pref ere nee tests (PPTs) to assess among-species variation in sociability and pair-bonding patterns and tested whether the nature of contact between individuals: direct contact (DC) versus nondirect contact (NDC) affected our results. We measured male pref ere nces as the time: 1) spe nt alone, 2) with familiar (partner), and 3) unfamiliar (stranger) female in the 3-chambered apparatus. Gerbil species differed strongly in sociability and male partner preferences. The time spent alone was a reliable indicator of species sociability indepe ndent of the nature of con tact, whereas the pattern and level of betwee n-species differe nces in male partner preferences depended on con tact type: DC PPTs, un like NDC-tests, discriminated well betwee n monogamous and promiscuous species. In the DC-tests, stranger-directed aggression and stranger avoidanee were observed both in the highly social monogamous M. unguiculatus and the solitary territorial promiscuous G. perpallidus, but not in the non territorial promiscuous M. meridianus. In M. unguiculatus, stranger avoidanee in the DC-tests increased the time spent with the partner, thus providing evidence of a partner preference that was not found in the NDC-tests, whereas in G. perpallidus, stran ger avoidance in creased the time spe nt alone. This first comparative experimental study of partner prefere nces in gerbils provides new in sights into the in terspecific variation in gerbil sociality and mating systems and sheds light on behavioral mechanisms un derlyi ng social fidelity and pair-b on ding.

关键词： gerbils mating systems partner preference test partner fidelity social systems stranger-directed aggression

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Role of social and individual experience in interaction of the meadow ant Formica pratensis （Hymenoptera： Formicidae） with ladybird imagines and hoverfly larvae

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Insect Science 2015年第3期22卷 440-450页

作者： Tatiana A. Novgorodova Institute of Systematics and Ecology of Animals Siberian Branch of the Russian Academy of Sciences Frunze str. 11 Novosibirsk 630091 Russia

The ability to recognize aphidophages is one of the key points in the protection ants provide aphids against their natural enemies. Behavior of honeydew collectors from nature （＂field,＂ control） and laboratory reared ＂naive＂ ants of Formica pratensis Retzius, which had never met either ＂mature＂ workers or aphids and aphidophages, was observed during their pairwise interactions with ladybird imagines and hoverfly larvae. The majority of the ＂naive＂ ants perceived ladybirds as an enemy at their first encounter attacking them immediately without any prior antennation. Ants seem to have a certain innate ＂enemy image＂ that lets them react very quickly to protect aphids. Hoverfly larvae were rarely attacked by both ＂field＂ and ＂naive＂ ants （〉 15%）. During tests with ladybirds ants from nature attacked them and also demonstrated the most aggressive reactions （series of bites and ＂death grip＂） less frequently than the ＂naive＂ ants. The percentage of ants avoiding aphidophages after a contact with their chemical defense （reflex bleeding and glue-like saliva） was significantly higher in the control group. Whereas the ＂naive＂ ants did not learn to avoid danger, foragers from nature usually tried to avoid negative experience and used tactics of ＂short bites.＂ Overall, experience has been proved to be unimportant for displaying key behavioral reactions underlying ant-ladybird interaction. However, accumulation of experience has been assumed to play an important role in the formation of behavioral strategy that allows honeydew collectors to drive aphidophages away with lower energy costs and avoid or minimize negative consequences of aphidophages＇ chemical defense.

关键词： ants aphidophages defense enemy recognition Harmonia axyridis Meligramma triangulifera

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Land use in agricultural landscapes with chernozems contaminated after Chernobyl accident: Can we be confident in radioecological safety of plant foodstuff?

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International Soil and Water Conservation research 2019年第2期7卷 158-166页

作者： Olga Komissarova Tatiana Paramonova Radioecology&Ecotoxicology Department Soil Science FacultyLomonosov Moscow State UniversityLeninskie Gory 1-12Moscow 119991Russia

Agricultural land use in the area of the post-Chemobyl Plavsk radioactive hotspot (Tula region,Central Russia) has raised a problem of radioecological safety of obtained plant *** of 137Cs activities and inventories in components of 'soil-plant' systems of the territory has been conducted in 2014-2017 in 10 agrosystems and 2 semi-natural *** was revealed that density of 137Cs contamination of arable chernozems and alluvial calcareous soils nowadays varies in a range 140-220 kBq/m2 and exceeds radiation safety standard by^3.5-6 *** plowing of the arable soils up to 30-cm in 1986-1987 resulted in decreasing of 137Cs inventories in rooting zone by ≈ 70% for crops cultivated with shallow disk plowing (wheat,barley),and by ≈ 35% for crops cultivated with middle plowing (buckwheat,amaranth,white mustard).The investigated plants and their compartments can be grouped on the basis of transfer factor values as follows:maize (stems and leaves)> amaranth> bromegrass > vegetation of dry meadow,galega,sunflower (seeds),vegetation of wet meadow > maize (grain),soybean (pods),barley (grain),buckwheat (grain),potatoes (tubers)> white mustard (seeds),wheat (grain).It is noticeable that generative plant compartments are characterized by less 137Cs activities in comparison with stems and leaves;and that 137Cs root uptake is not coincide with total flux of mineral nutrients in 'soil-plant' *** sum,137Cs soil-to-plant transfer in the area of the Plavsk radioactive hotspot is characterized by considerable discrimination,so 137Cs activities in plants are completely in accordance with national standards.

关键词： Radioactive soil contamination Caesium-137 137Cs Arable soils 'Soil-plant' system Chernobyl accident Radioecologically safe land use

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Age of maturation and behavioral tactics in male yellow ground squirrel Spermophilus fulvus during mating season

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Current Zoology 2014年第6期60卷 700-711页

作者： Nina A. VASILIEVA Ekaterina V. PAVLOVA Sergey V. NAIDENKO Andrey V.TCHABOVSKY A.N. Severtsov Institute of Ecology and Evolution Russian Academy of Sciences 33 Leninsky pr. Moscow 119071 Russia

Life-history theory predicts that in hibemators age of maturation is related positively to body size and negatively to the duration of active season aboveground. Yellow souslik is a large-sized ground squirrel with long hibernation, which suggests late maturation. We used four-year field observations of marked individuals to determine the age of maturation in males through analysis of age-dependent variation in body size, mass, androgen status, timing of spring emergence, ranging patterns and social behavior during the mating season. Yearling males were smaller, lighter, had lower level of fecal testosterone, emerged later and had smaller home ranges than older males. Social activity and the number of females encountered did not differ between age classes. After the second hibernation none of the studied parameters varied with age. Cluster analysis revealed two behavioral tactics：＂active＂ males （adults only） emerged earlier, ranged more widely, initiated more contacts, encountered more females and were heavier than ＂passive＂ males （both yearling and adult）. Thus, males of S. fulvus reached adult size and matured after two hibernations, which is relatively fast for such a big species with short active period. Indirect evidence for copulations and high variation among yearlings in all parameters suggest that some of them might successfully compete with adults. Active tactic of wandering and searching for females is energetically costly, and probably only adult males in good physical condition can afford it, whereas passive tactic of residing is energy saving and good for adults in poor condition and for yearlings that are continuing to grow.

关键词： Age of maturation Mating system Reproductive tactics Ground squirrel Spermophilusfulvus

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