24 research outputs found
Hourglass Charge-Three Weyl Phonons
Unconventional Weyl point with nonlinear dispersion features higher
topological charge and multiple topologically protected Fermi
arc states at its boundary. As a novel topological state, it has been
attracting widespread attention. However, the unconventional Weyl point with
has not yet been reported in realistic materials, even though
it has been theoretically proposed for more than a decade. In this work, based
on first-principles calculations and theoretical analysis, we predict the
existing material, -LiIO as the first realistic example with
this unconventional Weyl point. Particularly, in the phonon spectra of
-LiIO, two Weyl points with , connected by
time-reversal symmetry, appear at the neck crossing-point of a hourglass-type
band, leading to two hourglass charge-3 Weyl phonons. The symmetry protection
and the associated novel triple- and sextuple-helicoid surface arc states of
the hourglass charge-3 Weyl phonons are revealed. Our results uncover a hidden
topological character of -LiIO and also show that the phonon
spectra is a great platform for exploring unconventional topological states
Quadratic nodal point in a two-dimensional noncollinear antiferromagnet
Quadratic nodal point (QNP) in two dimensions has so far been reported only
in nonmagnetic materials and in the absence of spin-orbit coupling. Here, by
first-principles calculations and symmetry analysis, we predict stable QNP near
Fermi level in a two-dimensional kagome metal-organic framework material,
Cr(HAB), which features noncollinear antiferromagnetic ordering and
sizable spin-orbit coupling. Effective kp and lattice models are constructed to
capture such magnetic QNPs. Besides QNP, we find Cr(HAB) also hosts six
magnetic linear nodal points protected by mirror as well as symmetry.
Properties associated to these nodal points, such as topological edge states
and quantized optical absorbance, are discussed
Fully spin-polarized nodal loop semimetals in alkaline-metal monochalcogenide monolayers
Topological semimetals in ferromagnetic materials have attracted enormous
attention due to the potential applications in spintronics. Using the
first-principles density functional theory together with an effective lattice
model, here we present a new family of topological semimetals with a fully
spin-polarized nodal loop in alkaline-metal monochalcogenide ( = Li,
Na, K, Rb, Cs; = S, Se, Te) monolayers. The half-metallic ferromagnetism
can be established in monolayers, in which one nodal loop formed by two
crossing bands with the same spin components is found at the Fermi energy. This
nodal loop half-metal survives even when considering the spin-orbit coupling
owing to the symmetry protection provided by the mirror
plane. The quantum anomalous Hall state and Weyl-like semimetal in this system
can be also achieved by rotating the spin from the out-of-plane to the in-plane
direction. The monolayers hosting rich topological phases thus offer an
excellent materials platform for realizing the advanced spintronics concepts
Upper bound of a band complex
Band structure for a crystal generally consists of connected components in
energy-momentum space, known as band complexes. Here, we explore a fundamental
aspect regarding the maximal number of bands that can be accommodated in a
single band complex. We show that in principle a band complex can have no
finite upper bound for certain space groups. It means infinitely many bands can
entangle together, forming a connected pattern stable against
symmetry-preserving perturbations. This is demonstrated by our developed
inductive construction procedure, through which a given band complex can always
be grown into a larger one by gluing a basic building block to it. As a
by-product, we demonstrate the existence of arbitrarily large accordion type
band structures containing bands, with .Comment: 6 pages, 4 figure
Role of macrocyclic salen-type Schiff base ligands in one-dimensional Co(II) complexes for superior activities toward oxygen reduction/evolution reactions
Population pharmacokinetics of voriconazole and the role of CYP2C19 genotype on treatment optimization in pediatric patients.
The aim of this study was to evaluate factors that impact on voriconazole (VRC) population pharmacokinetic (PPK) parameters and explore the optimal dosing regimen for different CYP2C19 genotypes in Chinese paediatric patients. PPK analysis was used to identify the factors contributing to the variability in VRC plasma trough concentrations. A total of 210 VRC trough concentrations from 91 paediatric patients were included in the study. The median VRC trough concentration was 1.23 mg/L (range, 0.02 to 8.58 mg/L). At the measurement of all the trough concentrations, the target range (1.0~5.5 mg/L) was achieved in 52.9% of the patients, while subtherapeutic and supratherapeutic concentrations were obtained in 40.9% and 6.2% of patients, respectively. VRC trough concentrations were adjusted for dose (Ctrough/D), with normal metabolizers (NMs) and intermediate metabolizers (IMs) having significantly lower levels than poor metabolizers (PMs) (PN-P < 0.001, PI-P = 0.039). A one-compartment model with first-order absorption and elimination was suitable to describe the VRC pharmacokinetic characteristics. The final model of VRC PPK analysis contained CYP2C19 phenotype as a significant covariate for clearance. Dose simulations suggested that a maintenance dose of 9 mg/kg orally or 8 mg/kg intravenously twice daily was appropriate for NMs to achieve the target concentration. A maintenance dose of 9 mg/kg orally or 5 mg/kg intravenously twice daily was appropriate for IMs. Meanwhile, PMs could use lower maintenance dose and an oral dose of 6 mg/kg twice daily or an intravenous dose of 5mg/kg twice daily was appropriate. To increase the probability of achieving the therapeutic range and improving efficacy, CYP2C19 phenotype can be used to predict VRC trough concentrations and guide dose adjustments in Chinese pediatric patients
New Constructed EEM Spectra Combined with N-PLS Analysis Approach as an Effective Way to Determine Multiple Target Compounds in Complex Samples
Excitation–emission matrix (EEM) fluorescence spectroscopy has been applied to many fields. In this study, a simple method was proposed to obtain the new constructed three-dimensional (3D) EEM spectra based on the original EEM spectra. Then, the application of the N-PLS method to the new constructed 3D EEM spectra was proposed to quantify target compounds in two complex data sets. The quantitative models were established on external sample sets and validated using statistical parameters. For validation purposes, the obtained results were compared with those obtained by applying the N-PLS method to the original EEM spectra and applying the PLS method to the extracted maximum spectra in the concatenated mode. The comparison of the results demonstrated that, given the advantages of less useless information and a high calculating speed of the new constructed 3D EEM spectra, N-PLS on the new constructed 3D EEM spectra obtained better quantitative analysis results with a correlation coefficient of prediction above 0.9906 and recovery values in the range of 85.6–95.6%. Therefore, one can conclude that the N-PLS method combined with the new constructed 3D EEM spectra is expected to be broadened as an alternative strategy for the simultaneous determination of multiple target compounds