The effect of impurities on a superconductor with Bogoliubov Fermi surfaces (BFSs) is studied using a realistic tight-binding model. Based on the band structure composed of $d$-orbitals in tetragonal FeSe, whose S-doped sample is a potential material for BFS, we construct the superconducting state by introducing a time-reversal broken pair potential in terms of the band index. We further consider the effect of impurities on the BFS, where the impurity potential is defined as a local potential for the original $d$-orbitals. The self-energy is calculated using the (self-consistent) Born approximation, which shows an enhancement of the single-particle spectral weight on the Fermi surface. This is consistent with the previous phenomenological theory and is justified by the present more detailed calculation based on the FeSe-based material.
Using NZB/NZW F1 hybrid (B/W) mice, in model experiments for human systemic lupus erythematosus, the cytotoxic activity of thymocytes and splenic lymphocytes was studied against allogeneic target cells. Lymphocytes from female B/W mice were proved to have cytotoxic activity against target cells by the 51Cr release technique. The activity of splenic lymphocytes was a little higher than that of thymocytes. Antinuclear antibody (ANA) positive sera from B/W mice also accelerated the release of 51Cr from the target cells with the cooperation of complement. Pretreatment of B/W lymphocytes with DNA or addition of DNA to the culture medium did not affect their cytotoxicities. Natural thymocyto-toxic autoantibody was not found in B/W sera. The percentage of θ negative thymocytes in B/W mice (11-21%) was considerably higher than that in control mice (0-2%). From these results, it is supposed that the cell-mediated immunity against self-antigens besides autoantibodies constitutes a very important factor in the development of autoimmune diseases.
In spite of using antibiotics, patients with acute leukemia undergoing cytotoxic therapy have a high incidence of infectious complications. In order to reduce the risk of acquiring infections from the environment, patient isolator has recently been developed. The design of a new portable clean bed with laminar air flow system, a collaborative effort by the Kinki University and Nihon Ikakikai Inc., is specifically for experimental leukemia chemotherapy, but is adaptable as a protective environment to other problems in medical management.The wall of the head side consists of high efficiency particulate air (HEPA)-filter capable to removing 99.97% of all particles greater than 0.3 p. in diameter. The wall of the foot side consists of prefilter. The air passes through the bed from head- to foot side in a horizontal direction at a velocity of 0.5 m per second and the filtered air is recirculated via ceiling of the apparatus. The noise is 50 phone and the temperature is possible in moderate adjustment.Bacteriological samples from the environment were taken by means of exposed settle-plates laid at the two sites (head- and foot side) of the ventilated clean bed and in open wards (single and six beds room). As culture medium was used Tryptosoy agar containing 6-8% sheep blood, and the plates of 86 mm in diameter were exposed for 9 hours.Significant differences in the bacteriological results could be detected between the samples from the clean bed and from open wards. That is, comparing colony counts per one hour by sedimentation technique, 1.01 colonies at the head side, 1.19 at the foot side, 12.3 in single bed rooms and 25.05 in six beds rooms were observed respectively.According to the classification of air cleanliness classes (standard of U. S. A., No.209), 100-1000 classes were obtained by the slit sampler method regardless of frequency of medical staff entering.Identification of viable particles from the clean bed revealed staphylococcus epidermidis, coryn. ebacterium, γ-streptococcus and etc., being common skin flora.Six patients with acute leukemia have been nursed in the clean bed. Cleansing procedures by chlorhexidine significantly reduced but not eliminated the organisms on the skin.Despite of severe neutropenia during their stay in the clean bed, four of the six patients achieved remission of their leukemia without developed infection. One patient became feverish and died of endotoxic shock on the 14th day after the staff was forced to stop the fan of the apparatus because of his mental disorders. The other 5 patients were prevented from psychological disorders, such as sleeping disturbance, anxiety or irritation, by familiar staff-patient contact and by reforming of noise.
We study a superconductor Josephson junction with a Bogoliubov Fermi surface, employing McMillan's Green's function technique. The low-energy degrees of freedom are described by spinless fermions (bogolons), where the characteristic feature appears as an odd-frequency pair potential. The differential equation of the Green's function is reduced to the eigenvalue problem of the non-Hermitian effective Hamiltonian. The physical quantities such as the density of states and pair amplitude are then extracted from the obtained Green's function. We find that the zero energy local density of states at the interface decreases as the relative phase of the Josephson junction increases. This decrease is accompanied by the generation of an even-frequency pair amplitude near the interface. We also clarify that the $\pi$-junction-like current phase relation is realized in terms of bogolons. In contrast to conventional $s$-wave superconductor junctions, where even-frequency pairs dominate in the bulk and odd-frequency pairs are generated near the interface, our findings illuminate the distinct behaviors of junctions with Bogoliubov Fermi surfaces. We further explore spatial dependences of these physical quantities systematically using quasiclassical Green's functions.
The effect of impurities on a superconductor with Bogoliubov Fermi surfaces (BFSs) is studied using a realistic tight-binding model. Based on the band structure composed of $d$-orbitals in tetragonal $\mathrm{FeSe}$, whose S-doped sample is a potential material for a BFS, we construct the superconducting state by introducing a time-reversal broken pair potential in terms of the band index. We further consider the effect of impurities on the BFS, where the impurity potential is defined as a local potential for the original $d$-orbitals. The self-energy is calculated using the (self-consistent) Born approximation, which shows an enhancement of the single-particle spectral weight on the Fermi surface. This is consistent with the previous phenomenological theory and is justified by the present more detailed calculation based on the $\mathrm{FeSe}$-based material.
Chiral and axial materials offer platforms for intriguing phenomena, such as cross-correlated responses and chirality-induced spin selectivity. However, quantifying the properties of such materials has generally been considered challenging. Here, we demonstrate that the spatial distribution of the electron chirality, represented by $\Psi^\dagger \gamma^5 \Psi$ with the four-component Dirac field $\Psi$, characterizes the chirality and axiality of materials. Furthermore, we reveal that spin-derived electric polarization can serve as an effective indicator of material polarity. We present quantitative evaluations of electron chirality distribution and spin-derived electric polarization based on first-principles calculations. Additionally, we propose that electron chirality can be directly observed via circular dichroism in photoemission spectroscopy, which measures the difference between right- and left-handed circularly polarized light. Electron chirality and spin-derived electric polarization provide a new framework for quantifying chirality, axiality, and polarity in asymmetric materials, paving the way for the exploration of novel functional materials.
