132 research outputs found
Monte Carlo study of cuprate superconductors in a four-band - model: Role of orbital degrees of freedom
Understanding the complex phase diagram of cuprate superconductors is a
long-standing challenging problem. Recent studies have shown that orbital
degrees of freedom, both Cu orbitals and O orbitals, are a key
ingredient for a unified understanding of cuprate superconductors, including
the material dependence. Here we investigate a four-band - model derived
from the first-principles calculations with the variational Monte Carlo method,
which allows us to elucidate competing orders on an equal footing. The obtained
results can consistently explain the doping dependence of superconductivity,
antiferromagnetic and stripe phases, phase separation in the underdoped region,
and also novel magnetism in the heavily-overdoped region. Our four-band -
model with neighbouring intersite interactions is a minimal model to describe
the phase diagram comprehensively. The presence of orbitals is critical to
the charge-stripe features, which induce two types of stripe phases with
-wave and -wave bond stripe. On the other hand, the presence of
orbital is indispensable to material dependence of the
superconducting transition temperature (), and enhances local
magnetic moment as a source of novel magnetism in the heavily-overdoped region
as well. These findings beyond one-band description could provide a major step
toward a full explanation of unconventional normal state and high
in cuprate supercondutors.Comment: 15 pages, 10 figures, submitted to Phys. Rev. Research. arXiv admin
note: text overlap with arXiv:2105.1166
The Portrayal of Indonesian Image in 2007 Kompas Selected Short Stories: Social Problems, Criticisms and Hopes
Article aimed at exploring social problems reflected in 15 selected short stories printed in Kompas during 2007 both explicitly and implicitly. Specifically, this research is focused on the mapping of dominant social problems raised by the short stories, the social criticisms strongly voiced by the authors and the hopes of a better situation implicitly reflected in these interesting short stories. This study applies the Defamiliarization Effect promoted by Bertolt Brecht and Negative Dialectics or Negative Knowledge by Theodor Adorno, specifically in analyzing the literary works as a criticism tool. The result of the research shows that phenomena of social problems current lately in Indonesian context like identity, poverty, corruption, religious tensions, moral degradation, politics dirtiness, minority group problems, social security, natural disasters and the like are clearly seen and teased in these writings
Robust magnetic domain of Pt/Co/Au/Cr₂O₃/Pt stacked films with a perpendicular exchange bias
Magnetic domain pattern and magnetic domain wall motion are particularly important to understand the magnetization process. Here, we investigated the magnetization process of perpendicularly exchange-biased Pt/Co/Au/Cr₂O₃/Pt stacked films based on observations of the magnetic domain. In particular, in contrast to previous studies which use fully exchange-biased state, we used the bi-exchange-biased state. We found that the magnetic domain pattern at the remanent state was robust against magnetic-field cycling, which is relevant to the absence of the training effect. The magnetization process was followed by domain wall propagation in the increasing branch of the magnetization curve. In the decreasing branch, both nucleation of the reversed domain and domain wall propagation were involved. The former was accompanied by latency, suggesting that thermal activation played a significant role in the nucleation of the reversed domain.Yu Shiratsuchi, Saori Yoshida, Hiroaki Yoshida, Yoshinori Kotani, Kentaro Toyoki, Ryoichi Nakatani, Chiharu Mitsumata, and Tetsuya Nakamura, Journal of Applied Physics 127, 153902 (2020); https://doi.org/10.1063/5.0002240
Antiferromagnetic domain wall creep driven by magnetoelectric effect
We observed the magnetoelectric induced domain wall propagation in a Pt/Co/Au/Cr₂O₃/Pt stacked thin film based on magnetic domain observations using scanning soft X-ray magnetic circular dichroism microscopy. The antiferromagnetic (Cr₂O₃) domain wall velocity was estimated by a quasi-static approach using a pulsed voltage. At a pulse voltage amplitude of -12 V, corresponding to an electric field of -8.0 × 10²kV/cm, the domain wall velocity was very low, at 0.3 m/s. The domain wall velocity increased with increasing voltage amplitude, reaching 22 m/s at -20 V (-1.3 × 10³kV/cm). The change in the domain wall velocity with the applied voltage amplitude indicates the creep motion of the domain wall. Using a phenomenological model, we estimated the domain wall depinning energy, and found that the bulk and interface terms of the magnetic anisotropy affect the effective magnetic field to the same degree, suggesting that the magnetic domain wall motion may be controllable by the antiferromagnetic layer thickness.Yu Shiratsuchi, Hiroaki Yoshida, Yoshinori Kotani, Kentaro Toyoki, Thi Van Anh Nguyen, Tetsuya Nakamura, and Ryoichi Nakatani, APL Materials 6, 121104 (2018); https://doi.org/10.1063/1.5053928
Observation of the magnetoelectric reversal process of the antiferromagnetic domain
We investigated the switching process of the perpendicular exchange bias, which is driven by the magnetoelectric effect, by conducting magnetic domain observations using scanning soft X-ray magnetic circular dichroism microscopy. Isothermal and simultaneous application of magnetic and electric fields switches the perpendicular exchange bias polarity. The switching process proceeds by the nucleation and growth of reversed domains. The correspondence among the ferromagnetic/antiferromagnetic domains and exchange bias polarity indicates that interfacial antiferromagnetic spin/domain reversal is responsible for the magnetoelectric switching of the perpendicular exchange bias polarity.Yu Shiratsuchi, Shunsuke Watanabe, Hiroaki Yoshida, Noriaki Kishida, Ryoichi Nakatani, Yoshinori Kotani, Kentaro Toyoki, and Tetsuya Nakamura, Appl. Phys. Lett. 113, 242404 (2018); https://doi.org/10.1063/1.5053925
Formation of supramolecular hetero-triads by controlling the hydrogen bonding of conjugate bases with a diprotonated porphyrin based on electrostatic interaction
The thermodynamic stability of diprotonated saddle-distorted dodecaphenylporphyrin (H4DPP2+(X−)2) was controlled by the hydrogen-bonding strength of conjugate bases (X−) of strong acids (HX) or acids (R+-COOH) having positively charged moieties. The thermodynamic control of H4DPP2+(X−)2 made it possible to achieve selective formation of supramolecular hetero-triads, H4DPP2+(X−)(Cl−)
Current smoking status may be associated with overt albuminuria in female patients with type 1 diabetes mellitus: a cross-sectional study
Background
There are very few clinical reports that have compared the association between cigarette smoking
and microangiopathy in Asian patients with type 1 diabetes mellitus (T1DM). The objective of this study was to
assess the relationships between urinary protein concentrations and smoking and gender-based risk factors among
patients with T1DM.
Methods
A cross-sectional study of 259 patients with T1DM (men/women = 90/169; mean age, 50.7 years) who
visited our hospital for more than 1 year between October 2010 and April 2011 was conducted. Participants
completed a questionnaire about their smoking habits. Patient characteristics included gender, age, body mass
index, blood pressure, hemoglobin A1c, lipid parameters, and microangiopathy. Diabetic nephropathy (DN) was
categorized as normoalbuminuria (NA), microalbuminuria (MA), or overt albuminuria (OA) on the basis of the
following urinary albumin/creatinine ratio (ACR) levels: NA, ACR levels less than 30 mg/g creatinine (Cr); MA, ACR
levels between 30 and 299 mg/g Cr; and OA, ACR levels over 300 mg/g Cr.
Results
The percentages of current nonsmokers and current smokers with T1DM were 73.0% (n = 189) and 27.0%
(n = 70), respectively. In addition, the percentage of males was higher than that of females (52.2% versus 13.6%) in
the current smoking population. The percentage of DN was 61.8% (n = 160) in patients with NA, 21.6% (n = 56) in
patients with MA, and 16.6% (n = 43) in patients with OA. The percentage of males among OA patients was also
higher than that of females (24.4% versus 12.4%). However, current smoking status was associated with OA in
females with T1DM only [unadjusted odds ratio (OR), 4.13; 95% confidence interval (CI), 1.45–11.73, P < 0.01;
multivariate-adjusted OR, 5.41; 95% CI, 1.69–17.30, P < 0.01].
Conclusions
Based on our results in this cross-sectional study of Asian patients with T1DM, smoking might be a
risk factor for OA among female patients. Further research is needed of these gender-specific results
Broken Screw Rotational Symmetry in the Near-Surface Electronic Structure of -Stacked Crystals
We investigate the electronic structure of - and
by angle-resolved photoemission spectroscopy (ARPES) and
photoemission intensity calculations. Although in bulk form, these materials
are expected to exhibit band degeneracy in the plane due to screw
rotation and time-reversal symmetries, we observe gapped band dispersion near
the surface. We extract from first-principles calculations the near-surface
electronic structure probed by ARPES and find that the calculated photoemission
spectra from the near-surface region reproduce the gapped ARPES spectra. Our
results show that the near-surface electronic structure can be qualitatively
different from the bulk one due to partially broken nonsymmorphic symmetries.Comment: 6+11 pages, 4+13 figure
Low-dose Warfarin Functions as an Immunomodulator to Prevent Cyclophosphamide-induced NOD Diabetes
Warfarin has been used as an anticoagulant for a long time. Recently, the pleiotropic effect of warfarin has been investigated. As low-dose warfarin has been reported to have anti-inflammatory effect through suppression of IL-6 secretion and inhibit the immune-associated signal between Tyro3 and its ligand, Gas6, the effect of low-dose warfarin on autoimmune diabetes in NOD mice was examined. To investigate the anti-inflammatory effect of warfarin, IL-6 secretion by splenocytes was examined in the presence of various concentrations of warfarin. Low concentration of warfarin inhibited IL-6 secretion. mRNA expression of Rse, one of the Tyro3 receptor family members, and Gas6 were analyzed in NOD mice. It was detected in islets, splenocytes and bone-marrow derived dendritic cells. 0.25 mg/l or 0.50 mg/l of warfarin was orally administered to NOD mice as a cyclophosphamide-induced diabetes model. Oral administration of warfarin at much lower doses than those clinically used as an anticoagulant significantly reduced the degree of insulitis and diabetes incidence in this model. We previously demonstrated that anti-FasL Ab-treatment led to complete prevention of autoimmune diabetes in NOD mice. As Fas/FasL signaling is reported to be essential for cyclophosphamide-induced diabetes model, we extracted RNA from lymphocytes of the inguinal lymph nodes of anti-FasL Ab-treated NOD mice and performed real-time PCR to determine expression of Rse gene. Interestingly, the expression of Rse gene related to the blockade of Fas/FasL signaling was reduced to less than half the level of untreated mice. In conclusion, low-dose warfarin is a potential immunomodulator which can prevent autoimmune diabetes. Type 1 diabetes is a chronic autoimmune disease caused by autoreactive T cells promoting the specific destruction of insulin-producing β cells of the pancreatic islets (1,6). Nonobese diabetic (NOD) mouse is an animal model of human autoimmune diabetes (19). In the NOD mouse, diabetes develops as the result of a chronic inflammation that starts with leukocytic infiltration of islets from 3-5 weeks of age and gradually exacerbates until hyperglycemia develops after 16 weeks of age in a high percentage of female mice. Warfarin has been widely used for a long time as an oral anticoagulant agent. In addition, Kater et al. reported the pleiotropic effect of low-dose warfarin related with inflammation, demonstrating that low-dose warfarin inhibited inflammatory signal transduction through suppression of TNF-α induced IL-6 secretion from murine macrophages (12)
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