The process
e
+
e
-
→
n
n
¯
is studied in the experiment at the VEPP-2000
e
+
e
-
collider with the SND detector. The technique of the time measurements in the multichannel NaI(Tl) electromagnetic ...calorimeter is used to select
n
n
¯
events. The value of the measured cross section in the center-of-mass energy range from 1.894 to 2 GeV varies from 0.5 to 0.35 nb. The effective neutron timelike form factor is derived from the measured cross section and compared with the proton form factor. The ratio of the neutron electric and magnetic form factors is obtained from the analysis of the antineutron polar angle distribution and found to be consistent with unity.
The fast scintillation crystals such as pure CsI or LYSO(Ce) today are considered for timing measurements in future colliding beam experiments. The aim of such counters is to determine time of ...particles arrival with accuracy better than 100 ps. The work is devoted to investigation of influence of Cherenkov radiation on the time resolution of the detectors based on LYSO(Ce) crystals. The results of MC simulation and beam test are presented.
Abstract
The process
$$e^+e^-\rightarrow n{\bar{n}}$$
e
+
e
-
→
n
n
¯
is studied in the experiment at the VEPP-2000
$$e^+e^-$$
e
+
e
-
collider with the SND detector. The technique of the time ...measurements in the multichannel NaI(Tl) electromagnetic calorimeter is used to select
$$n{\bar{n}}$$
n
n
¯
events. The value of the measured cross section in the center-of-mass energy range from 1.894 to 2 GeV varies from 0.5 to 0.35 nb. The effective neutron timelike form factor is derived from the measured cross section and compared with the proton form factor. The ratio of the neutron electric and magnetic form factors is obtained from the analysis of the antineutron polar angle distribution and found to be consistent with unity.
Antimicrobial properties and thrombotic resistance of modern biomaterials depend on the composition and surface properties, such as roughness, topography and wettability. Tantalum oxynitrides ...demonstrate a wide range of modifications in the structure and elemental composition. Results show the effect of deposition conditions on the structure and surface properties of tantalum oxynitrides and further correlation with the biological response of TaON films in vitro tests.
Abstract The process $$e^+e^-\rightarrow n{\bar{n}}$$ e + e - → n n ¯ is studied in the experiment at the VEPP-2000 $$e^+e^-$$ e + e - collider with the SND detector. The technique of the time ...measurements in the multichannel NaI(Tl) electromagnetic calorimeter is used to select $$n{\bar{n}}$$ n n ¯ events. The value of the measured cross section in the center-of-mass energy range from 1.894 to 2 GeV varies from 0.5 to 0.35 nb. The effective neutron timelike form factor is derived from the measured cross section and compared with the proton form factor. The ratio of the neutron electric and magnetic form factors is obtained from the analysis of the antineutron polar angle distribution and found to be consistent with unity.
A wideband space-time channel model is defined, which captures the multiple dependencies and variability in multicell system-wide operating environments. The model provides a unified treatment of ...spatial and temporal parameters, giving their statistical description and dependencies across a large geographical area for three outdoor environments pertinent to third-generation cellular system simulations. Parameter values are drawn from a broad base of recently published wideband and multiple-antenna measurements. A methodology is given to generate fast-fading coefficients between a base station and a mobile user based on the summation of directional plane waves derived from the statistics of the space-time parameters. Extensions to the baseline channel model, such as polarized antennas, are given to provide a greater variety of spatial environments. Despite its comprehensive nature, the model's implementation complexity is reasonable so it can be used in simulating large-scale systems. Output statistics and capacities are used to illustrate the main characteristics of the model
Atomic force microscopy probing of cell elasticity Kuznetsova, Tatyana G; Starodubtseva, Maria N; Yegorenkov, Nicolai I ...
Micron (Oxford, England : 1993),
12/2007, Letnik:
38, Številka:
8
Journal Article
Recenzirano
Atomic force microscopy (AFM) has recently provided the great progress in the study of micro- and nanostructures including living cells and cell organelles. Modern AFM techniques allow solving a ...number of problems of cell biomechanics due to simultaneous evaluation of the local mechanical properties and the topography of the living cells at a high spatial resolution and force sensitivity. Particularly, force spectroscopy is used for mapping mechanical properties of a single cell that provides information on cellular structures including cytoskeleton structure. This entry is aimed to review the recent AFM applications for the study of dynamics and mechanical properties of intact cells associated with different cell events such as locomotion, differentiation and aging, physiological activation and electromotility, as well as cell pathology. Local mechanical characteristics of different cell types including muscle cells, endothelial and epithelial cells, neurons and glial cells, fibroblasts and osteoblasts, blood cells and sensory cells are analyzed in this paper.
Cr–O–N coatings were formed by cathodic arc evaporation at different O2/(N2+O2) relative oxygen concentrations onto HS6-5-2 (DIN standard) steel substrates. The chemical and phase composition, ...surface morphology on the as-deposited coatings were investigated by Wavelength Dispersive Spectrometry, X-ray Diffraction, Atomic Force Microscopy, Scanning Electron Microscopy and Raman Spectroscopy. The coatings deposited in pure nitrogen atmosphere had a cubic CrN structure. Structural properties of the coatings synthesized in mixed oxygen and nitrogen atmosphere depended strongly on the relative oxygen concentration. High relative oxygen concentration caused amorphization of the coating. XRD diffraction lines were shifted and broadened, indicating increasing stress and decreasing mean crystallite size, from 109nm for coatings deposited at relative oxygen concentration equal 0% to 23nm at 20%. The coatings formed at 50% relative oxygen concentration had a rhombohedral Cr2O3 structure with a grain size of about 11nm and lattice distortion of about 2%. Increasing the relative oxygen concentration also increased the surface roughness and the fraction of the surface rate covered by macroparticles.
•Cr-O-N coatings were deposited using cathodic arc evaporation•The increase in the relative oxygen concentration causes macropoarticle number increase•The coatings with oxygen concentrations to 23 at.% have cubic CrN structure and coating with 56 at.% - rhombohedral Cr2O3 structure•The coatings with oxygen concentrations to 23 at.% have lower roughness than coating with 56 at.%•The increase in the relative oxygen concentration causes grain size decrease
In this article, results of PET track-etched membranes (PET TeMs) hydrophobized by photo-induced graft polymerization of stearyl methacrylate (SM) inside the pores were presented. The effects of ...monomer concentration, time of irradiation and the nature of the solvent on the degree of grafting and membrane morphology were investigated. The PET TeMs with pore diameters ranging from 350 nm (pore density of 1 × 108 pore/cm2) to 3.05 µm (pore density of 1 × 106 pore/cm2) were hydrophobized and tested for oil–water separation by using hexadecane–water and chloroform–water emulsions. Studies have shown high separation performance for membranes (up to 1100 mL/m2·s) with large pore diameters while achieving a high degree of purification.
Ternary chromium based coatings (Cr-O-N) were formed on HS6-5-2 steel substrates using a vacuum arc plasma flux coating system at different relative oxygen concentrations, O2(x) = O2/(N2 + O2). The ...mechanical and tribological properties of the coatings were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), hardness measurements, wear test and adhesion tests (scratch test and Daimler-Benz test). Special attention was paid to coating adhesion and failure modes in the adhesion tests. The coefficient of friction, wear rate and adhesion decreased as the relative oxygen concentration increased. Hardness of the coatings showed the opposite effect, increasing from approximately 19 GPa–30 GPa. The dominant failure mode of Cr-O-N coatings was abrasion. Individual micro fragmentation was also observed for Cr-O-N coating with O2(x) = 20%.
•Cr-O-N coatings were deposited using cathodic arc evaporation at various relative oxygen concentration.•Adhesion is strongly dependent on oxygen concentration in the coating.•An increase in the relative oxygen concentration results in hardness increase and adhesion decrease.•Coefficient of friction and wear rate decrease with an increase in the relative oxygen concentration.
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