60 research outputs found
"Pudding Mold"-type Band as an Origin of Large Thermopower in tau-type Organic Conductors
We study the origin of the large thermopower in quasi-two-dimensional a
-type organic conductor, (), from the view point of a "pudding mold"-type band structure. We
calculate the electronic band structure using an \textit{ab initio} band
calculation package, and obtain a tight binding model fit to the \textit{ab
initio} band structure. Using the model and the Boltzmann's equation approach,
we calculate the temperature dependence of the Seebeck coefficient. We conclude
that the peculiar band structure is the origin of the large Seebeck coefficient
and the appearance of the maximum value at a certain temperature.Comment: proceedings of ISCOM 2009 (to be published in Physica B
Predicted risk of heart failure pandemic due to persistent SARS-CoV-2 infection using a three-dimensional cardiac model
「ポストコロナ」で警戒すべき心不全パンデミック --SARS-CoV-2の持続感染は心不全リスクを高める可能性--. 京都大学プレスリリース. 2023-12-27.Patients with chronic cardiomyopathy may have persistent viral infections in their hearts, particularly with SARS-CoV-2, which targets the ACE2 receptor highly expressed in human hearts. This raises concerns about a potential global heart failure pandemic stemming from COVID-19, an SARS-CoV-2 pandemic in near future. Although faced with this healthcare caveat, there is limited research on persistent viral heart infections, and no models have been established. In this study, we created an SARS-CoV-2 persistent infection model using human iPS cell-derived cardiac microtissues (CMTs). Mild infections sustained viral presence without significant dysfunction for a month, indicating persistent infection. However, when exposed to hypoxic conditions mimicking ischemic heart diseases, cardiac function deteriorated alongside intracellular SARS-CoV-2 reactivation in cardiomyocytes and disrupted vascular network formation. This study demonstrates that SARS-CoV-2 persistently infects the heart opportunistically causing cardiac dysfunction triggered by detrimental stimuli such as ischemia, potentially predicting a post COVID-19 era heart failure pandemic
Physical Dependence of the Sensitivity and Room-Temperature Stability of AuxGe1-x Thin Film Resistive Thermometers on Annealing Conditions
The reported nearly constant temperature sensitivity of appropriately annealed polycrystalline AuxGe1-x thin films at cryogenic temperatures would appear to make them promising materials for low mass, rapid thermal response resistive thermometers, but their adoption has been limited by difficulties in fabrication and uncertainties in annealing. In this work, we present a method of fabrication and annealing which allows control of the two most important parameters for these films: the room-temperature resistivity ρRT and the temperature sensitivity η(T), where η ≡ -d In R/d In T. We find that the dependence of ρRT on total anneal duration t for x≈0.18 is given by ρRT=ρ∞[1-Aexp(-t/τ)], where the limiting room-temperature resistivity ρ∞, the annealing coefficient A, and relaxation time τ are annealing temperature dependent parameters. The dependence of ρRT and temperature calibration ρ(T) on anneal duration can be minimized by annealing above 250 °C. Like ρRT, the sensitivity η(T) also depends on annealing temperature, with higher annealing temperatures corresponding to lower cryogenic sensitivities. In all cases η(T) can be well described by a polynomial expansion in In T from room temperature down to at least 2 K
Extremely Large Magnetoresistance in the Nonmagnetic Metal PdCoO2
Extremely large magnetoresistance is realized in the nonmagnetic layered
metal PdCoO2. In spite of a highly conducting metallic behavior with a simple
quasi-two-dimensional hexagonal Fermi surface, the interlayer resistance
reaches up to 35000% for the field along the [1-10] direction. Furthermore, the
temperature dependence of the resistance becomes nonmetallic for this field
direction, while it remains metallic for fields along the [110] direction. Such
severe and anisotropic destruction of the interlayer coherence by a magnetic
field on a simple Fermi surface is ascribable to orbital motion of carriers on
the Fermi surface driven by the Lorentz force, but seems to have been largely
overlooked until now.Comment: Phys. Rev. Lett. 111, 056601 (2013
Phase Diagram of Pressure-Induced Superconductivity in EuFe2As2 Probed by High-Pressure Resistivity up to 3.2 GPa
We have constructed a pressuretemperature () phase diagram of
-induced superconductivity in EuFeAs single crystals, via
resistivity () measurements up to 3.2 GPa. As hydrostatic pressure is
applied, an antiferromagnetic (AF) transition attributed to the FeAs layers at
shifts to lower temperatures, and the corresponding resistive
anomaly becomes undetectable for 2.5 GPa. This suggests that the
critical pressure where becomes zero is about 2.5
GPa. We have found that the AF order of the Eu moments survives up to
3.2 GPa without significant changes in the AF ordering temperature
. The superconducting (SC) ground state with a sharp transition
to zero resistivity at 30 K, indicative of bulk
superconductivity, emerges in a pressure range from 2.5
GPa to 3.0 GPa. At pressures close to but outside the SC phase, the
curve shows a partial SC transition (i.e., zero resistivity is not
attained) followed by a reentrant-like hump at approximately
with decreasing temperature. When nonhydrostatic pressure with a uniaxial-like
strain component is applied using a solid pressure medium, the partial
superconductivity is continuously observed in a wide pressure range from 1.1
GPa to 3.2 GPa.Comment: 7 pages, 6 figures, accepted for publication in Physical Review B,
selected as "Editors' Suggestion
Utilization of Nanoparticles Produced by Aqueous-Solution Methods – Formation of Acid Sites on CeO2-TiO2 Composite and 1-D TiO2 for Dye-Sensitized Solar Cells
Pressure-Induced Antiferromagnetic Bulk Superconductor EuFeAs
We present the magnetic and superconducting phase diagram of EuFeAs
for and . The antiferromagnetic phase of the
Eu moments is completely enclosed in the superconducting phase. The
upper critical field vs. temperature curves exhibit strong concave curvatures,
which can be explained by the Jaccarino-Peter compensation effect due to the
antiferromagnetic exchange interaction between the Eu moments and
conduction electrons.Comment: submitted to the proceedings of the M2S-IX Toky
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