600 research outputs found
Fast fluorescence dynamics in non-ratiometric calcium indicators
A fluorescence decay of high-affinity non-ratiometric Ca2+ indicator Oregon
Green BAPTA-1 (OGB-1) is analyzed with unprecedented temporal resolution in the
two-photon excitation regime. A triple exponential decay is shown to best fit
the fluorescence dynamics of OGB-1. We provide a new model for accurate
measurements of the free Ca2+ concentration and dissociation constants of
non-ratiometric calcium indicators.Comment: 3 pages, 2 figures, figures revised, added chi-square goodness of fi
Replacement of buffer gas with nitrogen in gas storage formations (models, methods, numerical experiments)
The paper gives description of the object of study - reservoir of the underground gas storage facility. A problem of replacement of buffer gas with nitrogen is raised and the problem formulations for its candidate solution are shown. A mathematical model of replacing buffer gas with nitrogen is proposed, which includes filtering model and convection model - diffusion of gases with concentrated sources. For the cases of unmixing gases the algorithm was developed for finding the propagation path of nitrogen. Numerical experiments were carried out
On the Application of a Monolithic Array for Detecting Intensity-Correlated Photons Emitted by Different Source Types
It is not widely appreciated that many subtleties are involved in the
accurate measurement of intensity-correlated photons; even for the original
experiments of Hanbury Brown and Twiss (HBT). Using a monolithic 4x4 array of
single-photon avalanche diodes (SPADs), together with an off-chip algorithm for
processing streaming data, we investigate the difficulties of measuring
second-order photon correlations g2 in a wide variety of light fields that
exhibit dramatically different correlation statistics: a multimode He-Ne laser,
an incoherent intensity-modulated lamp-light source and a thermal light source.
Our off-chip algorithm treats multiple photon-arrivals at pixel-array pairs, in
any observation interval, with photon fluxes limited by detector saturation, in
such a way that a correctly normalized g2 function is guaranteed. The impact of
detector background correlations between SPAD pixels and afterpulsing effects
on second-order coherence measurements is discussed. These results demonstrate
that our monolithic SPAD array enables access to effects that are otherwise
impossible to measure with stand-alone detectors.Comment: 17 pages, 6 figure
Spin susceptibility in superconductors without inversion symmetry
In materials without spatial inversion symmetry the spin degeneracy of the
conduction electrons can be lifted by an antisymmetric spin-orbit coupling. We
discuss the influence of this spin-orbit coupling on the spin susceptibility of
such superconductors, with a particular emphasis on the recently discovered
heavy Fermion superconductor CePt3Si. We find that, for this compound (with
tetragonal crystal symmetry,) irrespective of the pairing symmetry, the stable
superconducting phases would give a very weak change of the spin susceptibility
for fields along the c-axis and an intermediate reduction for fields in the
basal plane. We also comment on the consequences for the paramagnetic limiting
in this material.Comment: 10 pages, 3 figure
Graphene coating obtained in a cold-wall CVD process on the Co-Cr Alloy (L-605) for medical applications
Graphene coating on the cobalt-chromium alloy was optimized and successfully carried out by a cold-wall chemical vapor deposition (CW-CVD) method. A uniform layer of graphene for a large area of the Co-Cr alloy (discs of 10 mm diameter) was confirmed by Raman mapping coated area and analyzing specific G and 2D bands; in particular, the intensity ratio and the number of layers were calculated. The effect of the CW-CVD process on the microstructure and the mor-phology of the Co-Cr surface was investigated by scanning X-ray photoelectron microscope (SPEM), atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Nanoindentation and scratch tests were performed to determine mechanical properties of Co-Cr disks. The results of microbiological tests indicate that the studied Co-Cr alloys covered with a graphene layer did not show a pro-coagulant effect. The obtained results confirm the possibility of using the developed coating method in medical applications, in particular in the field of cardiovascular diseases
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