Hyperfine field assessment of the magnetic structure of ZrZn2

Time differential perturbed angular gamma-gamma-correlation (TDPAC) method on 111Cd nuclei probes inserted in ZrZn1.9 is used to measure the magnetic hyperfine fields (MHF) at Zr and Zn sites and the electric field gradient (EFG) Vzz at Zn sites as a function of temperature at various pressures and as a function of pressure at the temperature 4 K. Our data indicate that the local magnetic moment of Zr in the magnetically ordered state is substantially larger than its value obtained from the macroscopic measurements and that there is also an induced magnetic moment at the Zn site. We conclude that ZrZn2 is not a simple ferromagnet and discuss a possible type of its magnetic ordering.Comment: 7 pages, 6 figures, submitted for publicatio

Two stage pressure-induced Yb valence change in the Hexagonal Laves Phase YbAg2_2: Investigation by time differential perturbed angular γ\gamma-γ\gamma correlation spectroscopy method and density functional calculations

We have studied the C14 hexagonal Laves phase of YbAg$_2$ at normal conditions and under external pressure up to 19 GPa by the time-differential perturbed angular $\gamma-\gamma$ correlation spectroscopy (TDPAC) using $^{111}$Cd probe nuclei. Under pressure the valence of Yb undergoes a two stage transition from 2.8 to 3. The two stage scenario is characterized by two distinct quadrupole frequencies of $^{111}$Cd probes in silver sublattice, monotonically increasing with pressure and saturating at 8 and 16 GPa. Our experimental data are compared with the density functional studies of the electron band structure of YbAg$_2$, whose results are used for discussion and interpretation of these experiments. We have found that there are two different electric field gradients at inequivalent silver sites and that $4d$-states of silver participate in metal bonding, allowing for the formation of the hexagonal Laves phase

Average time scale for Dome Fuji ice core, East Antarctica

Three different approaches to ice-core age dating are employed to develop a depth-age relationship at Dome F: (1) correlation of the ice-core isotope record to the geophysical metronome(Milankovich surface temperature cycle) inferred from the deep borehole temperature profile at Vostok,(2) importing a known chronology from another(Devils Hole) paleoclimatic signal, and(3) direct ice sheet flow modeling. Inverse Monte Carlo sampling is used to constrain the accumulation rate reconstruction and ice flow simulations in order to find the best-fit glaciological time scale matched with the two other chronologies. General uncertainty of the different age estimates varies from 2 to 6kyr on average and reaches 6-14kyr at maximum. Whatever the causes of this discrepancy might be, they are thought to be of different origins, and the age errors are assumed to be independent. Thus, the average time scale for the Dome F ice core down to a depth of 2500m(ice age of 335kyr) is deduced consistently with all three age-depth relationships within the standard deviation limits of ±3.3kyr, and its accuracy is estimated as 1.4kyr on average. The constrained ice-sheet flow model allows extrapolation of the ice age-depth curve further to the glacier bottom and predicts the ages at depths of 2800, 3000, and 3050m to be 615±70, 1560±531, and 2985±1568kyr, respectively

DANSSino: a pilot version of the DANSS neutrino detector

DANSSino is a reduced pilot version of a solid-state detector of reactor antineutrinos (to be created within the DANSS project and installed under the industrial 3 GW(th) reactor of the Kalinin Nuclear Power Plant -- KNPP). Numerous tests performed at a distance of 11 m from the reactor core demonstrate operability of the chosen design and reveal the main sources of the background. In spite of its small size (20x20x100 ccm), the pilot detector turned out to be quite sensitive to reactor antineutrinos, detecting about 70 IBD events per day with the signal-to-background ratio about unity.Comment: 16 pages, 11 figures, 3 tables. arXiv admin note: substantial text overlap with arXiv:1304.369

Ice sheet modelling taking account of glacier ice compressibility

A mathematical treatment of the theory of glacier dynamics in relation to subsurface firn thickness, compressibility and the effects of densification. The analysis provides a theoretical basis for investigating heat and mass transfer processes in ice sheets with allowance for compressibility effects. -K.Clayto

Numerical scheme for non-linear model of supercritical fluid extraction from polydisperse ground plant material: Single transport system

© Published under licence by IOP Publishing Ltd.Numerical algorithm is developed for modelling non-linear mass transfer process in supercritical fluid extraction (SFE). The ground raw material is considered as polydisperse, characterized by discrete number of effective particle fractions. Two continuous interacting counterparts separated by permeable membrane are distinguished in plant material build-up. The apoplast plays role of transport channels during extraction, and symplast contains extractable oil. The complete SFE model is non-linear as a result of non-linearity of oil dissolution kinetics. The computational scheme is based on the finite-volume approximation method and Thomas elimination procedure. The resulting system of algebraic equations is solved iteratively. Special attention is paid to polydisperse substrates, when particle scale characteristics of all fractions interact with each other through pore phase concentration on the vessel scale. Stability of the developed algorithm is demonstrated in numerical tests. Special iterative procedure guarantees a monotonic decrease of oil content in individual particles of substrate. It is also shown that in the limit of the so-called shrinking core approach the number of mesh nodes on a particle scale should be increased

MEAN DESCRIPTION OF HEAT-TRANSFER PROCESSES IN FILTRATION IN CRACKED AND POROUS MEDIA.

On the basis of the method of averaging differential equations with rapidly oscillating coefficients, a mean equation describing the heat transfer in a filtering cracked medium is constructed. The effective transfer coefficients are calculated, and compared with experimental data