435 research outputs found
Strontium And Iron Substituted Lanthanum Nickelate As Cathode Material In Solid Oxide Fuel Cells
The MIEC La1.5Sr0.5Ni1-yFeyO4 (y=0.1-0.4) oxides have been studied as cathode materials with La0.88Sr0.12Ga0.82Mg0.18O3-δ (LSGM) electrolyte. Total conductivity, thermal expansion, oxygen nonstoichiometry, and chemical compatibility with LSGM and Ce0.8Sm0.2O1.9 (SDC) were determined. The following fuel cells were tested: La1.5Sr0.5Ni1-yFeyO4 (y=0.1, 0.2, 0.3, 0.4)/SDC/LSGM/Sr2N0.75Mg0.25MoO6 (SNMM) and La1.5Sr0.5Ni0.6Fe0.4O4/SDC/LSGM/SDC/NiO-SDC. For the former, the maximum power densities were 218, 274, 222, and 390 mW/cm2 at 850 °C in case of y equal to 0.1, 0.2, 0.3, and 0.4, respectively. The latter cell showed maximum power density of 341 mW/cm2 at 850°C
Cosmological Models with Fractional Derivatives and Fractional Action Functional
Cosmological models of a scalar field with dynamical equations containing
fractional derivatives or derived from the Einstein-Hilbert action of
fractional order, are constructed. A number of exact solutions to those
equations of fractional cosmological models in both cases is given.Comment: 14 page
Comparison of dynamic of autonomic control indices in cardiovascular system under the treatment by ACE inhibitor (Enalapril) and beta-blocker (Metoprolol) in patients with hypertension
The objective of the present research was to compare the influence of Enalapril and Metoprolol on synchronization of 0.1 Hz-regulation of heart and blood microcirculation. 42 patients aged 49±9 years old with hypertension I, II were included in the study. 0.1 Hz-oscillations in heart rate variability (HRV) and blood microcirculation were registered during the passive orthostatic sign while breathing spontaneously. The duration of each test was 10 minutes. Synchronization was estimated as a phase difference between 0.1 Hz-rhythms in heart rate and in filling of blood microcirculation. Quantitative measures of synchronization were also estimated. In addition frequency values of HRV spectrum in LF- and HF-ranges were assessed. Enalapril and Metoprolol had comparable effect on blood pressure reduction. Treatment with both Enalapril and Metoprolol in patients with significant vegetative dysfunction resulted in repair of functional interaction between 0.1 Hz-regulation of heart and blood microcirculation. Enalapril was preferred in hypertensive patients with prevalence of disorders of vegetative regulation of blood microcirculation. Metoprolol influenced positively on 0,1 Hz-rhythm synchronization in patients with predominance of heart vegetative regulation dysfunction and in patients with sympathicotonia. In patients with hypertension and initially normal level of synchronization of 0.1 Hz-mechanisms treatment with Enalapril or Metoprolol caused functional dissociation. Differentiated approach to the choice of hypertensive therapy should consider individual peculiarities of system vegetative dysfunction. The level of synchronization of 0.1 Hz-rhythms in cardiovascular system should especially be evaluated initially and during the treatmen
Comparative evaluation of autonomic regulation of circulation in patients undergone coronary artery bypass grafting or correction of acquired valvular heart disease
The aim of the research was to study the peculiarities of vegetative regulation of blood circulation in cardiac surgery patients who underwent coronary artery bypass grafting (CABG) or correction of acquired valvular heart disease (CAVHD). Material and Methods. In this study we included 42 patients (12 women; 63 (57; 67) years), who underwent CABG, and 36 patients (16 women; 58 (47; 65) years) who underwent CAVHD. The synchronous 15 minutes records of electrocardiogram and photoplethysmogram (PPG) were performed in all patients before and after surgery. Time domain and frequency domain measures of heart rate variability (HRV) and index of synchronization between low-frequency (LF) oscillations in HRV and PPG (index S) were analyzed. Results. Most studied autonomic indices did not have statistically significant differences between patients with CABG and CAVHD in the study stages, except for heart rate, which was higher in patients before CAVHD (p=0,013). Conclusion. The values of HRV and index S do not depend on the difference in the clinical status and the features of performed cardiac surgical interventions between patients with CABG and CAVHD.</p
Auger decay of degenerate and Bose-condensed excitons in CuO
We study the non-radiative Auger decay of excitons in CuO, in which two
excitons scatter to an excited electron and hole. The exciton decay rate for
the direct and the phonon-assisted processes is calculated from first
principles; incorporating the band structure of the material leads to a
relatively shorter lifetime of the triplet state ortho excitons. We compare our
results with the Auger decay rate extracted from data on highly degenerate
triplet excitons and Bose-condensed singlet excitons in CuO.Comment: 15 pages, revtex, figures available from G. Kavoulaki
Weak decays of : the non-leptonic case
In our previous study, we calculated the transition from factors of
using the QCD sum rules. Based on the factorization
approximation, the obtained form factors can be applied to evaluate the weak
non-leptonic decay rates of , where stands for a
light pseudoscalar or vector meson. We predict that the branching ratio for
inclusive non-leptonic two-body weak decays of which are realized via
the spectator mechanism, can be as large as , in
particular, the branching ratio of can reach
. Such values will be marginally accessed by the ability of
BESIII which will begin running very soon.Comment: 16 pages, revTex4, 1 figur
Fine structure of excitons in CuO
Three experimental observations on 1s-excitons in CuO are not consistent
with the picture of the exciton as a simple hydrogenic bound state: the
energies of the 1s-excitons deviate from the Rydberg formula, the total exciton
mass exceeds the sum of the electron and hole effective masses, and the
triplet-state excitons lie above the singlet. Incorporating the band structure
of the material, we calculate the corrections to this simple picture arising
from the fact that the exciton Bohr radius is comparable to the lattice
constant. By means of a self-consistent variational calculation of the total
exciton mass as well as the ground-state energy of the singlet and the
triplet-state excitons, we find excellent agreement with experiment.Comment: Revised abstract; 10 pages, revtex, 3 figures available from G.
Kavoulakis, Physics Department, University of Illinois, Urban
Quantum saturation and condensation of excitons in CuO: a theoretical study
Recent experiments on high density excitons in CuO provide evidence for
degenerate quantum statistics and Bose-Einstein condensation of this nearly
ideal gas. We model the time dependence of this bosonic system including
exciton decay mechanisms, energy exchange with phonons, and interconversion
between ortho (triplet-state) and para (singlet-state) excitons, using
parameters for the excitonic decay, the coupling to acoustic and low-lying
optical phonons, Auger recombination, and ortho-para interconversion derived
from experiment. The single adjustable parameter in our model is the
optical-phonon cooling rate for Auger and laser-produced hot excitons. We show
that the orthoexcitons move along the phase boundary without crossing it (i.e.,
exhibit a ``quantum saturation''), as a consequence of the balance of entropy
changes due to cooling of excitons by phonons and heating by the non-radiative
Auger two-exciton recombination process. The Auger annihilation rate for
para-para collisions is much smaller than that for ortho-para and ortho-ortho
collisions, explaining why, under the given experimental conditions, the
paraexcitons condense while the orthoexcitons fail to do so.Comment: Revised to improve clarity and physical content 18 pages, revtex,
figures available from G. Kavoulakis, Physics Department, University of
Illinois, Urban
Measurement of and between 3.12 and 3.72 GeV at the KEDR detector
Using the KEDR detector at the VEPP-4M collider, we have measured
the values of and at seven points of the center-of-mass
energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or
better than at most of energy points with a systematic uncertainty of
about . At the moment it is the most accurate measurement of in
this energy range
New precise determination of the \tau lepton mass at KEDR detector
The status of the experiment on the precise lepton mass measurement
running at the VEPP-4M collider with the KEDR detector is reported. The mass
value is evaluated from the cross section behaviour around the
production threshold. The preliminary result based on 6.7 pb of data is
MeV. Using 0.8 pb of data
collected at the peak the preliminary result is also obtained:
eV.Comment: 6 pages, 8 figures; The 9th International Workshop on Tau-Lepton
Physics, Tau0
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