8 research outputs found
Discovery of antiferromagnetic chiral helical ordered state in trigonal GdNiGa
We have performed magnetic susceptibility, magnetization, and specific heat
measurements on a chiral magnet GdNiGa, belonging to the trigonal space
group (\#155). A magnetic phase transition takes place at =
19.5 K. By applying a magnetic field along the axis at 2 K, the
magnetization curve exhibits two jumps at 3 kOe and = 45 kOe. To
determine the magnetic structure, we performed a resonant X-ray diffraction
experiment by utilizing a circularly polarized beam. It is shown that a
long-period antiferromagnetic (AFM) helical order is realized at zero field.
The Gd spins in the honeycomb layer are coupled in an antiferromagnetic manner
in the plane and rotate with a propagation vector = (0, 0, 1.485). The
period of the helix is 66.7 unit cells (~nm). In magnetic fields
above 3~kOe applied perpendicular to the helical axis, the AFM helical
order changes to an AFM order with = (0, 0, 1.5).Comment: 7 pages, 12 figure
Helicity Selection of the Cycloidal Order in Noncentrosymmetric EuIrGe
The magnetic helicities of the cycloidal ordering in EuIrGe, with a
noncentrosymmetric tetragonal structure, have been studied by circularly
polarized resonant X-ray diffraction. It is shown that the helicity of each
cycloidal domain is uniquely determined and satisfies the symmetry relations of
the point group of the crystal structure. The result shows that the
cycloidal helicity is determined by the Dzyaloshinskii-Moriya type
antisymmetric exchange interaction. The domain selection and the phase
transition by the external magnetic field along [100] and [110] have also been
studied. It is shown that the cycloidal plane prefers to be perpendicular to
the field and the transverse conical state is realized.Comment: 6 pages, 4 figures, 5 figures in the supplemental material, accepted
for publication in J. Phys. Soc. Jp
Crystal field excitation in the chiral helimagnet YbNiAl
Crystal field level scheme of a uniaxial chiral helimagnet YbNiAl,
exhibiting a chiral magnetic soliton lattice state by Cu substitution for Ni,
has been determined by inelastic neutron scattering. The ground and the first
excited doublets are separated by 44 K and are simply expressed as with and nearly equal to
. The easy axis of the crystal field anisotropy is the axis
when the excited levels are populated at high temperatures and high magnetic
fields. On the other hand, the magnetism at low temperatures and low magnetic
fields, where only the ground doublet is populated, is described by an easy
plane anisotropy which may be treated as an system with an anisotropic
-factor, and . An orbital dependent exchange
interaction is also discussed to explain the temperature dependence of the
magnetic susceptibility based on this level scheme.Comment: 9 pages, 7 figures, 2 figures in the supplemental material, accepted
for publication in Phys. Rev.
Structural Transition in the Hidden Ordered Phase of CeCoSi
We have performed X-ray diffraction experiments on a single crystalline
CeCoSi to investigate the unresolved ordered phase below K. We
have discovered that a triclinic lattice distortion takes place below ,
which is further modified in the subsequent antiferromagnetic ordered phase.
The structural domains can be selected by applying a magnetic field, indicating
that some electronic ordering exists behind and affects the magnetic anisotropy
in the hidden ordered phase below . The transition at , although the
order parameter is still unknown, is associated with the maximum in the
-axis lattice parameter. In magnetic fields along , the
structural transition temperature, named as , deviates from
and decreases with increasing the field, whereas increases. This
shows that the hidden ordered phase without triclinic distortion exists between
and . The results for are also
reported.Comment: 8 pages, 10 figures, 12 figures in the supplemental material,
submitted to J. Phys. Soc. Jp
The effects of 2,3-dimercapto-1-propanesulfonic acid (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) on the nephrotoxicity in the mouse during repeated cisplatin (CDDP) treatments
Previously, we reported that specific lower dose of sodium 2,3-dimercapto-1-propanesulfonic acid (DMPS) which is an antidote to heavy metal intoxication, inversely enhanced cisplatin (CDDP)-induced antitumor activity to S-180 cell-bearing mouse. This activity was only weak with meso-2,3-dimercaptosuccinic acid (DMSA), however. This study investigated the effects of lower doses of DMPS or DMSA on the nephrotoxicity and kinetics of CDDP. Kidney and blood isolated from female mice which received CDDP with or without DMPS or DMSA once daily for 4 days were provided for measuring levels of blood urea nitrogen (BUN) and transporter proteins (OCT2: organic cation transporter; MATE1: multidrug and toxin extrusion) mRNA, and CDDP-originated platinum, and TUNEL staining of renal tubular cells. DMPS or DMSA reduced effectively CDDP-induced BUN, and caused a moderate reduction of platinum in kidney. Additionally, both dimercapto-compounds restored the CDDP-reduced mRNA levels of transporter proteins (OCT2 and MATE1), and apparently suppressed the CDDP-induced apoptosis. These results suggest that DMPS, as well as DMSA, at approximate 17-fold dose (μmol/kg) of CDDP, has an enough potential to reverse the CDDP nephrotoxicity, and concomitant use of DMPS considering both dose and timing for administration is potentially useful for preventing nephrotoxicity and enhancing antitumor activity during CDDP chemotherapy
Relationships between Viral Load and the Clinical Course of COVID-19
To predict the clinical outcome of coronavirus disease-2019 (COVID-19), we examined relationships among epidemiological data, viral load, and disease severity. We examined viral loads of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) in fatal (15 cases), symptomatic/survived (133 cases), and asymptomatic cases (138 cases) using reverse transcription quantitative real-time PCR (RT-qPCR). We examined 5768 nasopharyngeal swabs (NPS) and attempted to detect the SARS-CoV-2 genome using RT-qPCR. Among them, the viral genome was detected using the method for the 370 NPS samples with a positive rate of 6.4%. A comparison of each age showed that the fatal case was higher than the survived case and asymptomatic patients. Survived cases were older than asymptomatic patients. Notably, the viral load in the fatal cases was significantly higher than in symptomatic or asymptomatic cases (p < 0.05). These results suggested that a high viral load of the SARS-CoV-2 in elderly patients at an early stage of the disease results in a poor outcome. We should, therefore, intervene early to prevent a severe stage of the disease in such cases
Detailed Evolutionary Analyses of the F Gene in the Respiratory Syncytial Virus Subgroup A
We performed evolution, phylodynamics, and reinfection-related antigenicity analyses of respiratory syncytial virus subgroup A (RSV-A) fusion (F) gene in globally collected strains (1465 strains) using authentic bioinformatics methods. The time-scaled evolutionary tree using the Bayesian Markov chain Monte Carlo method estimated that a common ancestor of the RSV-A, RSV-B, and bovine-RSV diverged at around 450 years ago, and RSV-A and RSV-B diverged around 250 years ago. Finally, the RSV-A F gene formed eight genotypes (GA1-GA7 and NA1) over the last 80 years. Phylodynamics of RSV-A F gene, including all genotype strains, increased twice in the 1990s and 2010s, while patterns of each RSV-A genotype were different. Phylogenetic distance analysis suggested that the genetic distances of the strains were relatively short (less than 0.05). No positive selection sites were estimated, while many negative selection sites were found. Moreover, the F protein 3D structure mapping and conformational epitope analysis implied that the conformational epitopes did not correspond to the neutralizing antibody binding sites of the F protein. These results suggested that the RSV-A F gene is relatively conserved, and mismatches between conformational epitopes and neutralizing antibody binding sites of the F protein are responsible for the virus reinfection
Isotropic parallel antiferromagnetism in the magnetic field induced charge-ordered state of SmRu4P12 caused by p−f hybridization
Nature of the field-induced charge-ordered phase (phase II) of SmRu4P12 has been investigated by resonant x-ray diffraction (RXD) and polarized neutron diffraction (PND), focusing on the relationship between the atomic displacements and the antiferromagnetic (AFM) moments of Sm. From the analysis of the interference between the nonresonant Thomson scattering and the resonant magnetic scattering, combined with the spectral function obtained from x-ray magnetic circular dichroism, it is shown that the AFM moment of Sm prefers to be parallel to the field (mAF // H), giving rise to large and small moment sites around which the P12 and Ru cage contract and expand, respectively. This is associated with the formation of the staggeredordering of the Γ7-like and Γ8-like crystal-field states, providing a strong piece of evidence for the charge order. PND was also performed to obtain complementary and unambiguous conclusion. In addition, isotropic and continuous nature of phase II is demonstrated by the field-direction invariance of the interference spectrum in RXD. Crucial role of the p- f hybridization is shown by resonant soft x-ray diffraction at the P K edge (1s ↔ 3p), where we detected a resonance due to the spin polarized 3p orbitals reflecting the AFM order of Sm