13 research outputs found
Vortex fluctuations in superconducting La-Sr-Cu-O
Vortex fluctuations in the system have been
studied as a function of magnetic field, temperature and carrier concentration
in order to determine the dimensionality of the fluctuations. For a
sample, there is a unique crossing-temperature on the magnetization vs.
temperature plots for all magnetic fields up to 7 T, and the data scale very
well with 2D fluctuation theory. At lower x-values where is much
smaller, there are two well defined crossing points, one at low fields
(typically less than 1 T) and another at high fields (typically 3-7 T). A fit
of the data to fluctuation theory shows that the low field crossing data scale
as 2D fluctuations and the high field crossing data scale as 3D fluctuations.
It would appear that as the magnetic field approaches , there is a 2D
to 3D cross-over where the low field 2D pancake vortex structure transforms
into a 3D vortex structure
Thermodynamic properties of excess-oxygen-doped La2CuO4.11 near a simultaneous transition to superconductivity and long-range magnetic order
We have measured the specific heat and magnetization {\it versus} temperature
in a single crystal sample of superconducting LaCuO and in a
sample of the same material after removing the excess oxygen, in magnetic
fields up to 15 T. Using the deoxygenated sample to subtract the phonon
contribution, we find a broad peak in the specific heat, centered at 50 K. This
excess specific heat is attributed to fluctuations of the Cu spins possibly
enhanced by an interplay with the charge degrees of freedom, and appears to be
independent of magnetic field, up to 15 T. Near the superconducting transition
(=0)= 43 K, we find a sharp feature that is strongly suppressed when
the magnetic field is applied parallel to the crystallographic c-axis. A model
for 3D vortex fluctuations is used to scale magnetization measured at several
magnetic fields. When the magnetic field is applied perpendicular to the
c-axis, the only observed effect is a slight shift in the superconducting
transition temperature.Comment: 8 pages, 8 figure
Multifunctional Magnetic-fluorescent Nanocomposites for Biomedical Applications
Nanotechnology is a fast-growing area, involving the fabrication and use of nano-sized materials and devices. Various nanocomposite materials play a number of important roles in modern science and technology. Magnetic and fluorescent inorganic nanoparticles are of particular importance due to their broad range of potential applications. It is expected that the combination of magnetic and fluorescent properties in one nanocomposite would enable the engineering of unique multifunctional nanoscale devices, which could be manipulated using external magnetic fields. The aim of this review is to present an overview of bimodal “two-in-one” magnetic-fluorescent nanocomposite materials which combine both magnetic and fluorescent properties in one entity, in particular those with potential applications in biotechnology and nanomedicine. There is a great necessity for the development of these multifunctional nanocomposites, but there are some difficulties and challenges to overcome in their fabrication such as quenching of the fluorescent entity by the magnetic core. Fluorescent-magnetic nanocomposites include a variety of materials including silica-based, dye-functionalised magnetic nanoparticles and quantum dots-magnetic nanoparticle composites. The classification and main synthesis strategies, along with approaches for the fabrication of fluorescent-magnetic nanocomposites, are considered. The current and potential biomedical uses, including biological imaging, cell tracking, magnetic bioseparation, nanomedicine and bio- and chemo-sensoring, of magnetic-fluorescent nanocomposites are also discussed
Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station
A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.</p
A calorimetric biosensor and its application for detecting a cancer cell with optical imaging
UNC93B1 is essential for the plasma membrane localization and signaling of Toll-like receptor 5
The proper trafficking and localization of Toll-like receptors (TLRs)
are important for specific ligand recognition and efficient signal
transduction. The TLRs sensing bacterial membrane components
are expressed on the cell surface and recruit signaling adaptors to
the plasma membrane upon stimulation. On the contrary, the
nucleotide-sensing TLRs are mostly found inside cells and signal
from the endolysosomes in an acidic pH-dependent manner. Trafficking
of the nucleotide-sensing TLRs from the endoplasmic
reticulum to the endolysosomes strictly depends on UNC93B1,
and their signaling is completely abolished in the 3d mutant mice
bearing the H412R mutation of UNC93B1. In contrast, UNC93B1
was considered to have no role for the cell surface-localized TLRs
and signaling via TLR1, TLR2, TLR4, and TLR6 is normal in the 3d
mice. Unexpectedly, we discovered that TLR5, a cell surface receptor
for bacterial protein flagellin, also requires UNC93B1 for
plasma membrane localization and signaling. TLR5 physically
interacts with UNC93B1, and the cells from the 3d or UNC93B1-
deficient mice not only lack TLR5 at the plasma membrane but
also fail to secret cytokines and to up-regulate costimulatory molecules
upon flagellin stimulation, demonstrating the essential
role of UNC93B1 in TLR5 signaling. Our study reveals that the role
of UNC93B1 is not limited to the TLRs signaling from the endolysosomes
and compels the further probing of the mechanisms underlying
the UNC93B1-assisted differential targeting of TLRs.119211sciescopu