1,687 research outputs found
Structural distinctions of Fe2O3-In2O3 composites obtained by various sol-gel procedures, and their gas-sensing features
New and various approaches to the sol–gel synthesis of advanced gas-sensing materials based on nanosized Fe2O3–In2O3 (9:1 mol) mixed
oxides, which differ in phase composition and grain size, have been considered in this paper. The correlation between the structural features of
the composites and their gas-sensing behavior has been established. It was found that multi-phase Fe2O3–In2O3 composites containing metastable
-Fe2O3 structure are characterized by the greatest sensitivity to both reducing (C2H5OH) and oxidizing (NO2) gases tested in this paper. The
influence of synthesis conditions on the structural peculiarities of the Fe2O3–In2O3 composites was studied in detail and the possibility to adjust
fine structure of the materials was demonstrated
Microscopic approach to pion-nucleus dynamics
Elastic scattering of pions from finite nuclei is investigated utilizing a
contemporary, momentum--space first--order optical potential combined with
microscopic estimates of second--order corrections. The calculation of the
first--order potential includes:\ \ (1)~full Fermi--averaging integration
including both the delta propagation and the intrinsic nonlocalities in the
- amplitude, (2)~fully covariant kinematics, (3)~use of invariant
amplitudes which do not contain kinematic singularities, and (4)~a
finite--range off--shell pion--nucleon model which contains the nucleon pole
term. The effect of the delta--nucleus interaction is included via the mean
spectral--energy approximation. It is demonstrated that this produces a
convergent perturbation theory in which the Pauli corrections (here treated as
a second--order term) cancel remarkably against the pion true absorption terms.
Parameter--free results, including the delta--nucleus shell--model potential,
Pauli corrections, pion true absorption, and short--range correlations are
presented. (2 figures available from authors)Comment: 13 page
Mitochondria, Cognitive Impairment, and Alzheimer's Disease
To date, the beta amyloid (Aβ) cascade hypothesis remains the main pathogenetic model of Alzheimer's disease (AD), but its role in the majority of sporadic AD cases is unclear. The “mitochondrial cascade hypothesis” could explain many of the biochemical, genetic, and pathological features of sporadic AD. Somatic mutations in mitochondrial DNA (mtDNA) could
cause energy failure, increased oxidative stress, and accumulation of Aβ, which in a vicious cycle reinforce the mtDNA damage and the oxidative stress. Despite the evidence of mitochondrial dysfunction in AD, no causative mutations in the mtDNA have been detected so far. Indeed, results of studies on the role of mtDNA haplogroups in AD are controversial. In this review we discuss the role of the mitochondria, and especially of the mtDNA,
in the cascade of events leading to neurodegeneration, dementia, and AD
Limits on GNSS Performance at High Latitudes
As climate change will likely lead to more of a human presence in the higher latitudes, it is important to consider how well our safety-critical positioning systems work near the poles. The orbits of the GPS (and other GNSS) preclude satellites with high elevation in these regions; hence, it is clear that at least vertical accuracy is impacted. This paper characterizes this positioning performance loss by developing lower bounds on GDOP as a function of receiver latitude. Examples with actual ephemeris data are included for comparison to the bounds
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