Search results for "[formula omitted] decay"
showing 10 items of 1452 documents
Extraction of radioactive positive ions across the surface of superfluid helium: A new method to produce cold radioactive nuclear beams
2003
Alpha-decay recoils 219Rn were stopped in superfluid helium and positive ions were extracted by electric field into the vapour phase. This first quantitative observation of extraction was successfully conducted using highly sensitive radioactivity detection. The efficiency for extraction across the liquid surface was 23 ± 4% at 1.60 K, the release time was 90 ± 10 ms at 1.50 K and the barrier for positive ions through a free superfluid-helium surface was 19.4 ± 4.5 K. The pulsed second sound proved to be effective in enhancing the extraction.
Enhancement of photoconversion efficiency in dye-sensitized solar cells exploiting pulsed laser deposited niobium pentoxide blocking layers
2015
Abstract Among all the photovoltaic technologies developed so far, dye-sensitized solar cells are considered as a promising alternative to the expensive and environmentally unfriendly crystalline silicon-based solar cells. One of the possible strategies employed to increase their photovoltaic efficiency is to reduce the charge recombination at the cell conductive substrate through the use of a compact blocking layer. In this paper, we report on the fabrication and characterization of dye-sensitized solar cells employing niobium pentoxide (Nb 2 O 5 ) thin film blocking layer deposited through the pulsed laser deposition technique on conductive substrates. The careful selection of the optimal…
The effect of interface roughness on exchange bias in La0.7Sr0.3MnO3 - BiFeO3 heterostructures
2016
We characterized the interfaces of heterostructures with different stack sequences of La0.7Sr0.3MnO3/BiFeO3 (LSMO/BFO) and BFO/LSMO using TEM revealing sharp and rough interfaces, respectively. Magnetometry and magnetoresistance measurements do not show a detectable exchange bias coupling for the multistack with sharp interface. Instead, the heterostructures with rough and chemically intermixed interfaces exhibit a sizable exchange bias coupling. Furthermore, we find a temperature-dependent irreversible magnetization behavior and an exponential decay of coercive and exchange bias field with temperature suggesting a possible spin-glass-like state at the interface of both stacks.
Positron lifetime measurements on neutron‐irradiated InP crystals
1996
Neutron‐irradiated InP single crystals have been investigated by positron‐lifetime measurements. The samples were irradiated with thermal neutrons at different fluences yielding concentrations for Sn‐transmuted atoms between 2×1015 and 2×1018 cm−3. The lifetime spectra have been analyzed into one exponential decay component. The mean lifetimes show a monotonous increase with the irradiation dose from 246 to 282 ps. The increase in the lifetime has been associated to a defect containing an Indium vacancy. Thermal annealing at 550 °C reduces the lifetime until values closed to those obtained for the as‐grown and conventionally doped InP crystals. navarrof@evalvx.ific.uv.es ; Jose.Ferrero@uv.es
Magnetic properties of Cd–Mg–Tb quasicrystal
2004
Abstract The magnetic properties of an icosahedral Cd–Mg–Tb quasicrystal were studied by dc magnetization and thermoremanent magnetization time decay measurements. An unusual temperature dependence of the susceptibility below freezing temperature can be attributed to the inhomogeneous sample structure. In addition to the quasicrystalline portion which exhibits a spin-glass transition at 12.5 K a part of the sample behaves like a paramagnet. During aging of the sample in air the spin-glass part transforms into the paramagnetic one. The linear M ∝ H dependence of the thermoremanent magnetization time decay on magnetic field is quite different as compared to canonical spin glasses.
Counting common perpendicular arcs in negative curvature
2013
Let $D^-$ and $D^+$ be properly immersed closed locally convex subsets of a Riemannian manifold with pinched negative sectional curvature. Using mixing properties of the geodesic flow, we give an asymptotic formula as $t\to+\infty$ for the number of common perpendiculars of length at most $t$ from $D^-$ to $D^+$, counted with multiplicities, and we prove the equidistribution in the outer and inner unit normal bundles of $D^-$ and $D^+$ of the tangent vectors at the endpoints of the common perpendiculars. When the manifold is compact with exponential decay of correlations or arithmetic with finite volume, we give an error term for the asymptotic. As an application, we give an asymptotic form…
Wood-inhabiting fungal communities : Opportunities for integration of empirical and theoretical community ecology
2022
Publisher Copyright: © 2021 The Author The interest in studying wood-inhabiting fungal communities has grown in recent years. This interest has mainly been motivated by the important roles of wood-inhabiting fungi in ecosystem functioning (e.g. nutrient cycling) and conservation biology (e.g. their sensitivity to forest management). In this paper, I argue that another important, but yet largely unexplored motivation for studying wood-inhabiting fungal communities, is their potential to advance fundamental community ecology. One major advantage of wood-inhabiting fungi as model systems is that they are organized as spatially well-defined metacommunities, thus conforming to the assumptions of…
High Temperature Study of Metamict Rinkite
2013
Metamict minerals contain radioactive elements that degrade their crystal structure. During the annealing process under ambient pressure in argon atmosphere the sample of metamict rinkite recrystallizes to the primary crystalline form at 700°C. Further heating leads to the formation of a new crystalline phase.
Potential of Antifungal Proteins (AFPs) to Control Penicillium Postharvest Fruit Decay
2021
Penicillium phytopathogenic species provoke severe postharvest disease and economic losses. Penicillium expansum is the main pome fruit phytopathogen while Penicillium digitatum and Penicillium italicum cause citrus green and blue mold, respectively. Control strategies rely on the use of synthetic fungicides, but the appearance of resistant strains and safety concerns have led to the search for new antifungals. Here, the potential application of different antifungal proteins (AFPs) including the three Penicillium chrysogenum proteins (PAF, PAFB and PAFC), as well as the Neosartorya fischeri NFAP2 protein to control Penicillium decay, has been evaluated. PAFB was the most potent AFP against …
Criteria for the Discovery of Chemical Elements
1976
The availability of suitable heavy-ion accelerators should make it possible to synthesize and identify additional heavy transuranium elements. Criteria for adequate proof that a new element has been synthesized or found in nature and identified are suggested. The basic criterion must be the proof that the atomic number of the new element is different from the atomic numbers of all previously known elements. Chemical identification constitutes an ideal proof; the procedure must be valid for application to individual atoms in an unequivocal manner. Also satisfactory is the identification of characteristic x rays in connection with the decay of the isotope of the new element. This is likely to…