47 research outputs found
Inhomogeneous magnetism in single crystalline SrCuIrO: Implications to phase-separation concepts
The single crystalline form of an insulator, SrCuIrO, is
shown to exhibit unexpectedly more than one magnetic transition (at 5 and 19 K)
with spin-glass-like magnetic susceptibility behaviour. On the basis of this
finding, viz., inhomogeneous magnetism in a chemically homogeneous material, we
propose that the idea of "phase- separation" described for manganites [1] is
more widespread in different ways. The observed experimental features enable us
to make a comparison with the predictions of a recent toy model [2] on {\it
magnetic} phase separation in an insulating environment.Comment: 4 pages, 4 figure
Magnetic anomalies in the spin chain system, SrCuZnIrO
We report the results of ac and dc magnetization (M) and heat-capacity (C)
measurements on the solid solution, SrCuZnIrO. While the Zn
end member is known to form in a rhombohedral pseudo one-dimensional
KCdCl structure with an antiferromagnetic ordering temperature of
(T =) 19 K, the Cu end member has been reported to form in a monoclinically
distorted form with a Curie temperature of (T =) 19 K. The magnetism of the
Zn compound is found to be robust to synthetic conditions and is broadly
consistent with the behavior known in the literature. However, we find a lower
magnetic ordering temperature (T) for our Cu compound (~ 13 K), thereby
suggesting that T is sensitive to synthetic conditions. The Cu sample
appears to be in a spin-glass-like state at low temperatures, judged by a
frequency dependence of ac magnetic susceptibility and a broadening of the C
anomaly at the onset of magnetic ordering, in sharp contrast to earlier
proposals. Small applications of magnetic field, however, drive this system to
ferromagnetism as inferred from the M data. Small substitutions for Cu/Zn (x =
0.75 or 0.25) significantly depress magnetic ordering; in other words, T
varies non-monotonically with x (T ~ 6, 3 and 4 K for x = 0.25, 0.5, and
0.67 respectively). The plot of inverse susceptibility versus temperature is
non-linear in the paramagnetic state as if correlations within (or among) the
magnetic chains continuously vary with temperature. The results establishComment: 7 pages, 7 figures, Revte
Bottom mixed layer oxygen dynamics in the Celtic Sea
The seasonally stratified continental shelf seas are highly productive, economically important environments which are under considerable pressure from human activity. Global dissolved oxygen concentrations have shown rapid reductions in response to anthropogenic forcing since at least the middle of the twentieth century. Oxygen consumption is at the same time linked to the cycling of atmospheric carbon, with oxygen being a proxy for carbon remineralisation and the release of CO2. In the seasonally stratified seas the bottom mixed layer (BML) is partially isolated from the atmosphere and is thus controlled by interplay between oxygen consumption processes, vertical and horizontal advection. Oxygen consumption rates can be both spatially and temporally dynamic, but these dynamics are often missed with incubation based techniques. Here we adopt a Bayesian approach to determining total BML oxygen consumption rates from a high resolution oxygen time-series. This incorporates both our knowledge and our uncertainty of the various processes which control the oxygen inventory. Total BML rates integrate both processes in the water column and at the sediment interface. These observations span the stratified period of the Celtic Sea and across both sandy and muddy sediment types. We show how horizontal advection, tidal forcing and vertical mixing together control the bottom mixed layer oxygen concentrations at various times over the stratified period. Our muddy-sand site shows cyclic spring-neap mediated changes in oxygen consumption driven by the frequent resuspension or ventilation of the seabed. We see evidence for prolonged periods of increased vertical mixing which provide the ventilation necessary to support the high rates of consumption observed
Oxygen dynamics in shelf seas sediments incorporating seasonal variability
Shelf sediments play a vital role in global biogeochemical cycling and are particularly important areas of oxygen consumption and carbon mineralisation. Total benthic oxygen uptake, the sum of diffusive and faunal mediated uptake, is a robust proxy to quantify carbon mineralisation. However, oxygen uptake rates are dynamic, due to the diagenetic processes within the sediment, and can be spatially and temporally variable. Four benthic sites in the Celtic Sea, encompassing gradients of cohesive to permeable sediments, were sampled over four cruises to capture seasonal and spatial changes in oxygen dynamics. Total oxygen uptake (TOU) rates were measured through a suite of incubation experiments and oxygen microelectrode profiles were taken across all four benthic sites to provide the oxygen penetration depth and diffusive oxygen uptake (DOU) rates. The difference between TOU and DOU allowed for quantification of the fauna mediated oxygen uptake and diffusive uptake. High resolution measurements showed clear seasonal and spatial trends, with higher oxygen uptake rates measured in cohesive sediments compared to the permeable sediment. The significant differences in oxygen dynamics between the sediment types were consistent between seasons, with increasing oxygen consumption during and after the phytoplankton bloom. Carbon mineralisation in shelf sediments is strongly influenced by sediment type and seasonality
Seasonal oxygen, nitrogen and phosphorus benthic cycling along an impacted Baltic Sea estuary: regulation and spatial patterns
Development and Applications of Fluorogen/Light-Up RNA Aptamer Pairs for RNA Detection and More.
The central role of RNA in living systems made it highly desirable to have noninvasive and sensitive technologies allowing for imaging the synthesis and the location of these molecules in living cells. This need motivated the development of small pro-fluorescent molecules called "fluorogens" that become fluorescent upon binding to genetically encodable RNAs called "light-up aptamers." Yet, the development of these fluorogen/light-up RNA pairs is a long and thorough process starting with the careful design of the fluorogen and pursued by the selection of a specific and efficient synthetic aptamer. This chapter summarizes the main design and the selection strategies used up to now prior to introducing the main pairs. Then, the vast application potential of these molecules for live-cell RNA imaging and other applications is presented and discussed.journal article2020importe
Violence as adaptation strategy? Dealing with hardship in prison
Young prisoners are a population group reckoned as highly strained and marginalised. Violence can be understood as a possible adaptation strategy to cope with the hardship that might even be intensified by the imprisonment. The following contribution goes into this matter and presents numerous findings of a longitudinal study about young people in youth custody. In doing so, several features of importation and deprivation respectively are put into relation to violence among young male prisoners
Constrained peptides mimic a viral suppressor of RNA silencing
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