126 research outputs found
Magnetic properties of GdZn (T = Fe, Co) investigated by X-ray diffraction and spectroscopy
We investigate the magnetic and electronic properties of the GdZn
( = Fe and Co) compounds using X-ray resonant magnetic scattering (XRMS),
X-ray absorption near-edge structure (XANES) and X-ray magnetic circular
dichroism (XMCD) techniques. The XRMS measurements reveal that the
GdCoZn compound has a commensurate antiferromagnetic spin structure
with a magnetic propagation vector =
below the N\'eel temperature ( 5.7 K). Only the Gd ions carry a magnetic moment forming an
antiferromagnetic structure with magnetic representation . For the
ferromagnetic GdFeZn compound, an extensive investigation was
performed at low temperature and under magnetic field using XANES and XMCD
techniques. A strong XMCD signal of about 12.5 and 9.7 is observed
below the Curie temperature ( 85 K) at the Gd- and edges,
respectively. In addition, a small magnetic signal of about 0.06 of the
jump is recorded at the Zn -edge suggesting that the Zn 4 states are spin
polarized by the Gd 5 extended orbitals
Incommensurate phonon anomaly and the nature of charge density waves in cuprates
While charge density wave (CDW) instabilities are ubiquitous to
superconducting cuprates, the different ordering wavevectors in various cuprate
families have hampered a unified description of the CDW formation mechanism.
Here we investigate the temperature dependence of the low energy phonons in the
canonical CDW ordered cuprate LaBaCuO. We discover
that the phonon softening wavevector associated with CDW correlations becomes
temperature dependent in the high-temperature precursor phase and changes from
a wavevector of 0.238 reciprocal space units (r.l.u.) below the ordering
transition temperature up to 0.3~r.l.u. at 300~K. This high-temperature
behavior shows that "214"-type cuprates can host CDW correlations at a similar
wavevector to previously reported CDW correlations in non-"214"-type cuprates
such as YBaCuO. This indicates that cuprate CDWs may
arise from the same underlying instability despite their apparently different
low temperature ordering wavevectors.Comment: Accepted in Phys. Rev. X; 9 pages; 5 figures; 3 pages of
supplementary materia
Temporary inhibition of Moloney-murine sarcoma virus (M-MSV) induced-tumours by adoptive transfer of ricin-treated T-lymphocytes.
The potential use of tumour-specific T-lymphocytes loaded with ricin in cell targeting experiments was investigated. Moloney-murine sarcoma virus (M-MSV)-specific T-lymphocytes, obtained in mass mixed leucocyte-tumour cell culture (MLTC) and a M-MSV-specific cytotoxic T-lymphocyte (CTL) clone, were incubated with 125I-labelled ricin in order to evaluate toxin uptake and release. The internalized ricin (4.5 X 10(-17) mol and 6.5 X 10(-17) mol per 10(2) MLTC and CTL clone cells, respectively) was released rapidly during the first 30 min following treatment, and at a constant but slower rate over the next few hours. The cytotoxic activity of ricin-treated cells evaluated against antigen-related target cells, in a short term incubation 51Cr release assay, was unaffected during the first 30 min after treatment but decreased with time over the next few hours. However, the growth of antigen related as well as of unrelated tumour cells was strongly inhibited by the addition of ricin-treated cells to the culture system, thus indicating that released ricin is toxic for untreated target cells. The in vivo localization pattern of ricin-treated radiolabelled MLTC cells was found to be comparable with that of untreated cells 1 h after i.v. injection into syngeneic sublethally irradiated mice. After 6 h, however, more radiolabel was recovered from the liver of mice receiving ricin-treated MLTC cells. Ricin-treated M-MSV-specific T-lymphocytes were injected i.v. into tumour bearing sublethally irradiated mice. A temporary tumour growth inhibition (up to 6 days) was achieved following transfer of low doses of ricin-treated MLTC or CTL clone cells (1 X 10(6) and 0.5 X 10(6), respectively). In contrast, in M-MSV injected control mice, receiving only free toxin (from 5 to 20 ng) or untreated tumour-specific effector cell tumours grew progressively. The therapeutic effect was apparently specific since the injection of ricin-treated alloreactive T-lymphocytes did not influence tumour growth. These results suggest that M-MSV-specific T-lymphocytes loaded with ricin can deliver toxin to the target tumour mass and have a transient therapeutic effect
Development and Technology Assessment of the Analytical Performance of an Eight Position Dynamic Olfactometer
The European technical standard \u201cAir Quality\u2014Determination of Odour Concentration by Dynamic Olfactometry\u201d adopts dynamic olfactometry, a sensorial methodology based on the employment of a panel of human assessors, as the official methodology for the measurement of odour concentration in gas samples. The olfactometer is the device, useful to dilute the odor sample with neutral air, according to precise ratios and to present it to the panel for the analysis. The present paper describes the development of an Italian olfactometer, able to host eight assessors, designed to improve the instrumental performance of the devices actually present on the market, and to increase the accuracy and repeatability of the olfactometric measurement. In particular, in the paper the principal features of the instrumental device and the results of calibrations of dilution valves will be shown
Static Charge Density Wave Order in the Superconducting State of La2-xBaxCuO4
Charge density wave (CDW) correlations feature prominently in the phase
diagram of the cuprates, motivating competing theories of whether fluctuating
CDW correlations aid superconductivity or whether static CDW order coexists
with superconductivity in inhomogeneous or spatially modulated states. Here we
report Cu -edge resonant x-ray photon correlation spectroscopy (XPCS)
measurements of CDW correlations in superconducting LaBaCuO
. Static CDW order is shown to exist in the superconducting state at
low temperatures and to persist up to at least 85\% of the CDW transition
temperature. We discuss the implications of our observations for how
\emph{nominally} competing order parameters can coexist in the cuprates.Comment: 6 pages, 5 figures, Accepted in Phys. Rev. B Rapid Communication
Hyperhoneycomb Iridate β-li2iro3 As A Platform For Kitaev Magnetism.
A complex iridium oxide β-Li(2)IrO(3) crystallizes in a hyperhoneycomb structure, a three-dimensional analogue of honeycomb lattice, and is found to be a spin-orbital Mott insulator with J(eff)=1/2 moment. Ir ions are connected to the three neighboring Ir ions via Ir-O(2)-Ir bonding planes, which very likely gives rise to bond-dependent ferromagnetic interactions between the J(eff)=1/2 moments, an essential ingredient of Kitaev model with a spin liquid ground state. Dominant ferromagnetic interaction between J(eff)=1/2 moments is indeed confirmed by the temperature dependence of magnetic susceptibility χ(T) which shows a positive Curie-Weiss temperature θ(CW)∼+40  K. A magnetic ordering with a very small entropy change, likely associated with a noncollinear arrangement of J(eff)=1/2 moments, is observed at T(c)=38  K. With the application of magnetic field to the ordered state, a large moment of more than 0.35  μ(B)/Ir is induced above 3 T, a substantially polarized J(eff)=1/2 state. We argue that the close proximity to ferromagnetism and the presence of large fluctuations evidence that the ground state of hyperhoneycomb β-Li(2)IrO(3) is located in close proximity of a Kitaev spin liquid.11407720
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