58 research outputs found

    Magnetic Nanotherapy by Magnetosensitive Nanocomplexes with Different Magnetic Properties of the Walker 256 Carcinosarcoma

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    The magnetic nanocomplex (MNC) comprised of Fe3O4 nanoparticles (NP) and doxorubicin (DOXO) with a saturation magnetic magnetic moment m3 = 10.5 emu/g during magnetic nanotherapy initiated greater antitumor effect than MNC with m3 = 8.55 emu/g. After treatment of Walker 256 tumor the concentration of iron ions in the blood serum of animals with tumor increased and did not depend on the magnetic properties of MNC

    The Estimation of Microtopographic Parametres of Fractographical Surfaces by Fourier−Hartley Mehods

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    Розглянуто питання стереомікротопографії (поверхонь металів, твердих тіл). Пропонується за даними РЕМ-стереовимірювань апроксимувати цифрові моделі мікрорельєфу методами Фур’є−Хартлі з наступним визначенням крутизни, кривини, спектральної щільності. ; The problems of stereomicrotopography (of metal surfaces, of solid body’s) are considered. The approximation of microrelief digital models by Fourier−Hartley methods on the basis of REMstereomeasurements datas (a steepness, a curvature, spectral density) are proposed

    Shift of fibril‐forming ability of the designed α‐helical coiled‐coil peptides into the physiological pH region

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    Recently, we designed a short α‐helical fibril‐forming peptide (αFFP) that can form α‐helical nanofibrils at acid pH. The non‐physiological conditions of the fibril formation hamper biomedical application of αFFP. It was hypothesized that electrostatic repulsion between glutamic acid residues present at positions (g) of the αFFP coiled‐coil sequence prevent the fibrillogenesis at neutral pH, while their protonation below pH 5.5 triggers axial growth of the fibril. To test this hypothesis, we synthesized αFFPs where all glutamic acid residues were substituted by glutamines or serines. The electron microscopy study confirmed that the modified αFFPs form nanofibrils in a wider range of pH (2.5-11). Circular dichroism spectroscopy, sedimentation, diffusion and differential scanning calorimetry showed that the fibrils are α‐helical and have elongated and highly stable cooperative tertiary structures. This work leads to a better understanding of interactions that control the fibrillogenesis of the αFFPs and opens opportunities for their biomedical applicatio

    On fiber dispersion models: exclusion of compressed fibers and spurious model comparisons

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    Fiber dispersion in collagenous soft tissues has an important influence on the mechanical response, and the modeling of the collagen fiber architecture and its mechanics has developed significantly over the last few years. The purpose of this paper is twofold, first to develop a method for excluding compressed fibers within a dispersion for the generalized structure tensor (GST) model, which several times in the literature has been claimed not to be possible, and second to draw attention to several erroneous and misleading statements in the literature concerning the relative values of the GST and the angular integration (AI) models. For the GST model we develop a rather simple method involving a deformation dependent dispersion parameter that allows the mechanical influence of compressed fibers within a dispersion to be excluded. The theory is illustrated by application to simple extension and simple shear in order to highlight the effect of exclusion. By means of two examples we also show that the GST and the AI models have equivalent predictive power, contrary to some claims in the literature. We conclude that from the theoretical point of view neither of these two models is superior to the other. However, as is well known and as we now emphasize, the GST model has proved to be very successful in modeling the data from experiments on a wide range of tissues, and it is easier to analyze and simpler to implement than the AI approach, and the related computational effort is much lower

    Magnetic Nanotherapy by Magnetosensitive Nanocomplexes with Different Magnetic Properties of the Walker 256 Carcinosarcoma

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    The magnetic nanocomplex (MNC) comprised of Fe3O4 nanoparticles (NP) and doxorubicin (DOXO) with a saturation magnetic magnetic moment m3 = 10.5 emu/g during magnetic nanotherapy initiated greater antitumor effect than MNC with m3 = 8.55 emu/g. After treatment of Walker 256 tumor the concentration of iron ions in the blood serum of animals with tumor increased and did not depend on the magnetic properties of MNC

    Performance of a fine-sampling electromagnetic calorimeter prototype in the energy range from 1 to 19 GeV

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    The fine-sampling electromagnetic calorimeter prototype has been experimentally tested using the 1-19 GeV/c tagged beams of negatively charged particles at the U70 accelerator at IHEP, Protvino. The energy resolution measured by electrons is Delta{E}/E=2.8%/\sqrt{E} + 1.3%. The position resolution for electrons is Delta{x}=3.1 + 15.4/sqrt{E} mm in the center of the cell. The lateral non-uniformity of the prototype energy response to electrons and MIPs has turned out to be negligible. Obtained experimental results are in a good agreement with Monte-Carlo simulations.Comment: Article is prepared for pdflatex using the class elsart. 13 pages, 9 figures in 11 PDF file

    Physical-mechanical aspects of degradation of heat-echange tubes metal for steam-generators of the type PGW-1000

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    By metallography and scanning electron microscopy the effect of titanium carbonitride and silicon carbide on degradation of steel 08X18H10T was revealed on heat exchanging tubes (HET) of steam generators of powergenerating units of WWER-1000. The role of structural features of steam generators on nucleation and growth of operational defects of HET is shown.За допомогою металографії та растрової електронної мікроскопії встановлено вплив включень карбонитридів титану і карбіду кремнію на деградацію сталі 08Х18Н10Т у теплообмінних трубах (ТОТ) парогенераторів енергоблоків ВВЕР-1000. Показана також роль конструкційних особливостей парогенераторів у зародженні і зростанні експлуатаційних дефектів ТОТ.С помощью металлографии и растровой электронной микроскопии установлено воздействие включений карбонитридов титана и карбида кремния на деградацию стали 08Х18Н10Т в теплообменных трубах (ТОТ) парогенераторов энергоблоков ВВЭР-1000. Показана также роль конструкционных особенностей парогенераторов в зарождении и росте эксплуатационных дефектов ТОТ

    Feasibility studies for the measurement of time-like proton electromagnetic form factors from p¯ p→ μ+μ- at P ¯ ANDA at FAIR

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    This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, | GE| and | GM| , using the p¯ p→ μ+μ- reaction at P ¯ ANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at P ¯ ANDA , using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is p¯ p→ π+π-, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented

    Nonlinear optics and saturation behavior of quantum dot samples under continuous wave driving

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    The nonlinear optical response of self-assembled quantum dots is relevant to the application of quantum dot based devices in nonlinear optics, all-optical switching, slow light and self-organization. Theoretical investigations are based on numerical simulations of a spatially and spectrally resolved rate equation model, which takes into account the strong coupling of the quantum dots to the carrier reservoir created by the wetting layer states. The complex dielectric susceptibility of the ground state is obtained. The saturation is shown to follow a behavior in between the one for a dominantly homogeneously and inhomogeneously broadened medium. Approaches to extract the nonlinear refractive index change by fringe shifts in a cavity or self-lensing are discussed. Experimental work on saturation characteristic of InGa/GaAs quantum dots close to the telecommunication O-band (1.24-1.28 mm) and of InAlAs/GaAlAs quantum dots at 780 nm is described and the first demonstration of the cw saturation of absorption in room temperature quantum dot samples is discussed in detail
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