233 research outputs found
Unconventional spin density wave in Bechgaard salt (TMTSF)2NO3
Among many Bechgaard salts, TMTSF2NO3 exhibits very anomalous low temperature
properties. Unlike conventional spin density wave (SDW), TMTSF2NO3 undergoes
the SDW transition at \T_SDW\approx 9.5 K and the low temperature
quasiparticle excitations are gapless. Also, it is known that TMTSF2NO3 does
not exhibit superconductivity even under pressure, while FISDW is found in
TMTSF2NO3 only for P=8.5 kbar and B>20 T. Here we shall show that both the
angle dependent magnetoresistance data and the nonlinear Hall resistance of
TMTSF2NO3 at ambient pressure are interpreted satisfactory in terms of
unconventional spin density wave (USDW). Based on these facts, we propose a new
phase diagram for Bechgaards salts.Comment: 4 pages, 4 figs, RevTe
Best practice in reporting corona studies:Minimum Information about Nanomaterial Biocorona Experiments (MINBE)
Machine learning provides predictive analysis into silver nanoparticle protein corona formation from physicochemical properties
Proteins encountered in biological and environmental systems bind to engineered nanomaterials (ENMs) to form a protein corona (PC) that alters the surface chemistry, reactivity, and fate of the ENMs. Complexities such as the diversity of the PC and variation with ENM properties and reaction conditions make the PC population difficult to predict. Here, we support the development of predictive models for PC populations by relating biophysicochemical characteristics of proteins, ENMs, and solution conditions to PC formation using random forest classification. The resulting model offers a predictive analysis into the population of PC proteins in Ag ENM systems of various ENM size and surface coatings. With an area under the receiver operating characteristic curve of 0.83 and F1-score of 0.81, a model with strong performance has been constructed based upon experimental data. The weighted contribution of each variable provides recommendations for mechanistic models based upon protein enrichment classification results. Protein biophysical properties such as pI and weight are weighted heavily. Yet, ENM size, surface charge, and solution ionic strength also proved essential to an accurate model. The model can be readily modified and applied to other ENM PC populations. The model presented here represents the first step toward robust predictions of PC fingerprints
Restoration of Adiponectin-Connexin43 Signaling Mitigates Myocardial Inflammation and Dysfunction in Diabetic Female Rats
Anisotropic charge dynamics in the quantum spin-liquid candidate -(BEDT-TTF)Cu(CN)
We have in detail characterized the anisotropic charge response of the dimer
Mott insulator -(BEDT-TTF)\-Cu(CN) by dc conductivity, Hall
effect and dielectric spectroscopy. At room temperature the Hall coefficient is
positive and close to the value expected from stoichiometry; the temperature
behavior follows the dc resistivity . Within the planes the dc
conductivity is well described by variable-range hopping in two dimensions;
this model, however, fails for the out-of-plane direction. An unusually broad
in-plane dielectric relaxation is detected below about 60 K; it slows down much
faster than the dc conductivity following an Arrhenius law. At around 17 K we
can identify a pronounced dielectric anomaly concomitantly with anomalous
features in the mean relaxation time and spectral broadening. The out-of-plane
relaxation, on the other hand, shows a much weaker dielectric anomaly; it
closely follows the temperature behavior of the respective dc resistivity. At
lower temperatures, the dielectric constant becomes smaller both within and
perpendicular to the planes; also the relaxation levels off. The observed
behavior bears features of relaxor-like ferroelectricity. Because
heterogeneities impede its long-range development, only a weak tunneling-like
dynamics persists at low temperatures. We suggest that the random potential and
domain structure gradually emerge due to the coupling to the anion network.Comment: 14 pages, 13 figure
Cooperative dynamics in charge-ordered state of alpha-(BEDT-TTF)2I3
Electric-field-dependent pulse measurements are reported in the
charge-ordered state of alpha-(BEDT-TTF)2I3. At low electric fields up to about
50 V/cm only negligible deviations from Ohmic behavior can be identified with
no threshold field. At larger electric fields and up to about 100 V/cm a
reproducible negative differential resistance is observed with a significant
change in shape of the measured resistivity in time. These changes critically
depend whether constant voltage or constant current is applied to the single
crystal. At high enough electric fields the resistance displays a dramatic drop
down to metallic values and relaxes subsequently in a single-exponential manner
to its low-field steady-state value. We argue that such an electric-field
induced negative differential resistance and switching to transient states are
fingerprints of cooperative domain-wall dynamics inherent to two-dimensional
bond-charge density wave with ferroelectric-like nature.Comment: 6 pages, 4 figures, resubmitted to Phys. Rev.
Origin of Low-Energy Excitations in Charge-Ordered Manganites
The low-energy excitations in the charge-ordered phase of polycrystalline
La0.25Ca0.75MnO3 are explored by frequency-domain terahertz spectroscopy. In
the frequency range from 4 cm^-1 to 700 cm^-1 (energies 0.4 meV to 90 meV) and
at temperatures down to 5 K, we do not detect any feature that can be
associated with the collective response of the spatially modulated charge
continuum. In the antiferromagnetically ordered phase, broad absorption bands
appear in the conductivity and permittivity spectra around 30 cm^-1 and 100
cm^-1 which are assigned to former acoustic phonons optically activated due to
a fourfold superstructure in the crystal lattice. Our results indicate that
characteristic energies of collective excitations of the charge-ordered phase
in La0:25Ca0:75MnO3, if any, lie below 1 meV. At our lowest frequencies of only
few wavenumbers a strong relaxation is observed above 100 K connected to the
formation of the charge-ordered state.Comment: 5 pages, 3 figure
Influence of doping on the Hall coefficient in Sr_{14-x}Ca_xCu_24O_41
We present Hall-effect measurements of two-leg ladder compounds
Sr_{14-x}Ca_xCu_24O_41 (0 <= x <= 11.5) with the aim to determine the number of
carriers participating in dc transport. Distribution of holes between the
ladder and chain subsystems is one of the crucial questions important for
understanding the physics of these compounds. Our Hall effect and resistivity
measurements show typical semiconducting behavior for x < 11.5. However, for
x=11.5, the results are completely different, and the Hall coefficient and
resistivity behavior is qualitatively similar to that of high temperature
copper-oxide superconductors. We have determined the effective number of
carriers at room temperature and compared it to the number of holes in the
ladders obtained by other experimental techniques. We propose that going from
x=0 to x=11.5 less than 1 hole per formula unit is added to the ladders and is
responsible for a pronounced change in resistivity with Ca doping.Comment: 8 pages, 7 figures, revised versio
Charge-density wave formation in Sr_{14}Cu_{24}O_{41}
The electrodynamic response of the spin-ladder compound
SrCaCuO () has been studied from
radiofrequencies up to the infrared. At temperatures below 250 K a pronounced
absorption peak appears around 12 cm in SrCuO for
the radiation polarized along the chains/ladders ().
In addition a strongly temperature dependent dielectric relaxation is observed
in the kHz - MHz range. We explain this behavior by a charge density wave which
develops in the ladders sub-system and produces a mode pinned at 12 cm.
With increasing Ca doping the mode shifts up in frequency and eventually
disappears for because the dimensionality of the system crosses over from
one to two dimensions, giving way to the superconducting ground state under
pressure.Comment: One name added to author list 4 pages, 2 figures, email:
[email protected]
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