73 research outputs found
Topological surface states hybridized with bulk states of Bi-doped PbSb2Te4 revealed in quasiparticle interference
Topological surface states of Bi-doped PbSb2Te4 [Pb(Bi0.20Sb0.80)2Te4] are
investigated through analyses of quasiparticle interference (QPI) patterns
observed by scanning tunneling microscopy. Interpretation of the experimental
QPI patterns in the reciprocal space is achieved by numerical QPI simulations
using two types of surface density of states produced by density functional
theory calculations or a kp surface state model. We found that the Dirac point
(DP) of the surface state appears in the bulk band gap of this material and,
with the energy being away from the DP, the isoenergy contour of the surface
state is substantially deformed or separated into segments due to hybridization
with bulk electronic states. These findings provide a more accurate picture of
topological surface states, especially at energies away from the DP, providing
valuable insight into the electronic properties of topological insulators.Comment: 7+8 pages, 4+5 figure
Thermal aggregation of human immunoglobulin G in arginine solutions: Contrasting effects of stabilizers and destabilizers
Arginine is widely used as aggregation suppressor of proteins in biotechnology and pharmaceutics. However, why the effect of arginine depends on the types of proteins and stresses, including monoclonal antibodies, is still unclear. Here we investigated the precise processes of the thermal aggregation of human immunoglobulin G (IgG) in the presence of additives. As expected, arginine was the best additive to suppress the formation of insoluble aggregates during heat treatment, though it was unable to preserve the monomer content. A systematic analysis of the additives showed that sugars and kosmotropic ion inhibit the formation of soluble oligomers. These behaviors indicate that the thermal aggregation of IgG occurs by (i) the formation of soluble oligomers, which is triggered by the unfolding process that can be stabilized by typical osmolytes, and (ii) the formation of insoluble aggregates through weak cluster–cluster interactions, which can be suppressed by arginine. Understanding the detailed mechanism of arginine will provide useful information for the rational formulation design of antibodies
Field resilient superconductivity in atomic layer crystalline materials
The recent study [S. Yoshizawa et al., Nature Communications 12, 1 (2021)]
reported the field resilient superconductivity, that is, the enhancement of an
in-plane critical magnetic field exceeding the paramagnetic
limiting field in an atomic layer crystalline ()-In on
a Si(111) substrate. The present article elucidates the origin of the observed
field resilient noncentrosymmetric superconductivity in the highly crystalline
two dimensional material. We developed the quasiclassical theory by
incorporating the Fermi surface anisotropy together with an anisotropic spin
splitting specific to atomic layer crystalline systems. The enhancement of the
rescaled by the critical temperature at zero field occurs not
only due to the disorder effect but also to an anisotropic non-ideal Rashba
spin texture depending on the field direction. We also study the parity mixing
effect to show the enhancement of is limited in the
moderately clean regime because of the fragile -wave pairing against
nonmagnetic scattering in the case of the dominant odd parity component of a
pair wavefunction. Furthermore, from the analysis of the transition line, we
identify the field resilience factor taking account of the scattering and
suppression of paramagnetic effects and discuss the origin of the field
resilient superconductivity. Through the fitting of the data,
the normal state electron scattering is discussed, mainly focusing on the role
of atomic steps on a Si(111) surface.Comment: 13 pages, 6 figures, 1 tabl
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