1,339 research outputs found
Topological surface electronic states in candidate nodal-line semimetal CaAgAs
We investigate systematically the bulk and surface electronic structure of
the candidate nodal-line semimetal CaAgAs by angle resolved photoemission
spectroscopy and density functional calculations. We observed a metallic,
linear, non--dispersive surface band that coincides with the
high-binding-energy part of the theoretical topological surface state, proving
the topological nontriviality of the system. An overall downshift of the
experimental Fermi level points to a rigid-band-like -doping of the samples,
due possibly to Ag vacancies in the as-grown crystals.Comment: 6 pages, 5 figure
Chern insulators and high Curie temperature Dirac half-metal in two-dimensional metal-organic frameworks
Two-dimensional (2D) magnetic materials with nontrivial topological states
have drawn considerable attention recently. Among them, 2D metal-organic
frameworks (MOFs) are standing out due to their advantages, such as the easy
synthesis in practice and less sensitivity to oxidation that are distinctly
different from inorganic materials. By means of density-functional theory
calculations, we systematically investigate the electronic and topological
properties of a class of 2D MOFs X(C21H15N3) (X = transition metal element from
3d to 5d). Excitingly, we find that X(C21H15N3) (X = Ti, Zr, Ag, Au) are Chern
insulators with sizable band gaps (~7.1 meV). By studying a four-band effective
model, it is revealed that the Chern insulator phase in X(C21H15N3) (X = Ti,
Zr, Ag, Au) is caused cooperatively by the band inversion of the p orbitals of
the C21H15N3 molecule and the intrinsic ferromagnetism of X(C21H15N3).
Additionally, Mn(C21H15N3) is a Dirac half-metal ferromagnet with a high Curie
temperature up to 156 K. Our work demonstrates that 2D MOFs X(C21H15N3) are
good platforms for realizing Quantum anomalous Hall effect and designing novel
spintronic devices based on half-metals with high-speed and long-distance spin
transport.Comment: 16 pages, 4 figure
Room-temperature antiferromagnetic CrSe monolayer with tunable metal-insulator transition in ferroelectric heterostructures
Recently, there has been a rapidly growing interest in two-dimensional (2D)
transition metal chalcogenide monolayers (MLs) due to their unique magnetic and
electronic properties. By using an evolutionary algorithm and first-principles
calculations, we report the discovery of a previously unexplored, chemically,
energetically, and thermodynamically stable 2D antiferromagnetic (AFM) CrSe ML
with a N\'eel temperature higher than room temperature. Remarkably, we predict
an electric field-controllable metal-insulator transition (MIT) in a van der
Waals (vdW) heterostructure comprised of CrSe ML and ferroelectric Sc2CO2. This
tunable transition in CrSe/Sc2CO2 heterostructure is attributed to the change
in the band alignment between CrSe and Sc2CO2 caused by the ferroelectric
polarization reversal in Sc2CO2. Our findings suggest that 2D AFM CrSe ML has
important potential applications in AFM spintronics, particularly in the gate
voltage conducting channel.Comment: 13 Pages, 4 Figure
Decentralized coordination between active distribution network and multi-microgrids through a fast decentralized adjustable robust operation framework
Electrically tunable Gilbert damping in van der Waals heterostructures of two-dimensional ferromagnetic metals and ferroelectrics
Tuning the Gilbert damping of ferromagnetic (FM) metals via a nonvolatile way
is of importance to exploit and design next-generation novel spintronic
devices. Through systematical first-principles calculations, we study the
magnetic properties of the van der Waals heterostructure of two-dimensional FM
metal CrTe2 and ferroelectric (FE) In2Te3 monolayers. The ferromagnetism of
CrTe2 is maintained in CrTe2/In2Te3 and its magnetic easy axis can be switched
from in-plane to out-of-plane by reversing the FE polarization of In2Te3.
Excitingly, we find that the Gilbert damping of CrTe2 is tunable when the FE
polarization of In2Te3 is reversed from upward to downward. By analyzing the
k-dependent contributions to the Gilbert damping, we unravel that such
tunability results from the changed intersections between the bands of CrTe2
and Fermi level on the reversal of the FE polarizations of In2Te3 in
CrTe2/In2Te3. Our work provides an appealing way to electrically tailor Gilbert
dampings of two-dimensional FM metals by contacting them with ferroelectrics.Comment: 4 Figures, accepted by Applied Physics Letter
Study on properties of Al film on CFRP after cryogenic-thermal cycling
AbstractAl film on CFRP has been tested by cryogenic-thermal cycling according to the especial condition of space. Properties of aluminum film have been characterized by electron pull apparatus, XRD and SEM. The result shows that the adhesion of Al film increases slowly at early stage of cryogenic-thermal cycling. When the times of cryogenic-thermal cycling exceed 50, the adhesion of Al film becomes stability, and then the adhesion of Al film decrease slowly when cycling times from 100 to 600. After 600 times, the adhesion of Al film becomes stability again. The microcrack appears on the surface of Al film after 50 times, and the amounts of microcrack increase and microcrack is coarsening versus times of cryogenic-thermal cycling. The structure of Al film is changing slowly during cryogenic-thermal cycling
Expressions and clinical significances of CD133 protein and CD133 mRNA in primary lesion of gastric adenocacinoma
<p>Abstract</p> <p>Background</p> <p>To study on expressions and clinical significances of CD133 protein and CD133 mRNA in primary lesion of gastric adenocarcinoma (GC).</p> <p>Methods</p> <p>Expressions of CD133 protein by immunostaining (99 cases) and CD133 mRNA by semi-quantitative RT-PCR (31 cases) were detected in primary lesion and in noncancerous gastric mucosa tissue (NCGT). Correlations of CD133 protein expression with clinicopathological parameters and post-operative survival were analyzed. Relations of CD133 mRNA level with Ki-67 labeling index (LI), and lymphatic metastasis were assessed too.</p> <p>Results</p> <p>Brown particles indicating CD133 protein positivity occurred in some parts of tumor cells and epithelium. Expressive percentage of CD133 protein positivity was significantly higher in subgroups with >5 cm diameter (<it>P </it>= 0.041), later TNM stage (<it>P </it>= 0.044), severer lymph node metastasis (<it>P </it>= 0.017), occurrences of lymphatic invasion (<it>P </it>= 0.000) and vascular invasion (<it>P </it>= 0.000) respectively. Severer invasion depth (<it>P </it>= 0.011), lymph node metastasis occurrence (<it>P </it>= 0.043) and later TNM stage (<it>P </it>= 0.049) were the independent risk factors for CD133 protein expression. Average brightness scale value (BSV) of CD133 mRNA was significantly higher in subgroups with >5 cm diameter (<it>P </it>= 0.041), lymph node metastasis occurrence (<it>P </it>= 0.004) and in lower Ki-67 LI (<it>P </it>= 0.02). Relative analysis revealed that BSV of CD133 mRNA related positively to metastatic lymphatic nodes ratio (<it>P </it>= 0.008) and metastatic lymph node number (<it>P </it>= 0.009), but negatively to Ki-67 LI (<it>P </it>= 0.009). Survival of positive subgroup of CD 133 protein was significantly poorer (<it>P </it>= 0.047). Lymph node metastasis occurrence (<it>P </it>= 0.042), later TNM stage (<it>P </it>= 0.046) and CD 133 protein positive expression (<it>P </it>= 0.046) were respectively the independent risk factors to survival.</p> <p>Conclusion</p> <p>Higher expressive level of CD133 mRNA is associated to lower Ki-67 LI and severer lymphatic metastasis. Therefore, the expressive level of CD133 mRNA can play an appropriate role to reflect the status of lymph node metastasis and proliferation of GC. CD133 protein expression is closely related with larger tumor, later TNM stage, lymphtic metastasis and survival of GC.</p
The Resistance Phenotype and Molecular Epidemiology of Klebsiella pneumoniae in Bloodstream Infections in Shanghai, China, 2012â2015
Effect of YiShenJianPi recipe on semen quality and sperm mitochondria in mice with oligoasthenozoospermia induced by tripterygium glycosides
BackgroundïŒKidney tonifying - spleen strengthening method being one of the modalities for treatment of astheno-oligozoospermia is currently commonly used in the clinical setting. To investigate the mechanism of YiShenJianPi (YSJP) Recipe, used in Traditional Chinese Medicine to benefit âthe kidneyâ and strengthen âthe spleenâ.Materials and Methods: Oligoasthenozoospermia, male BALB/c mice were randomly divided into normal control, disease model, positive control, low-dosage and high-dosage groups. Oligoasthenozoospermia was induced by tripterygium glucosides intragastric administration before treatment started.Through using computer-aided sperm analysis to test the changes in sperm quality, utilizing flow cytometry to test the percentage of sperm with normal mitochondrial transmembrane potential (JC-1 + %), utilizing X-ray microscopy to observe epididymal sperm ultra-microstructure placing special emphasis and photographing the differences in mitochondria of the flagellum region.Results: Compared with DM, sperm quality of the treated mice was significantly better (P<0.05, respectively). Compared with PC, the LD group had significantly better quality sperms, while the parameters in the HD group were numerically better. Compared with NC, all other groups had significantly lower percentage of sperms with normal mitochondrial membrane potential. In PC, LD and HD groups, the percentage of sperms with normal mitochondrial membrane potential was significantly higher than that of D. The 9+9+2 mitochondrial sheath structure was complete in NC but damaged in DM. In the treatment groups, this structure was fairly clear.Conclusion: YSJP improved semen quality with oligoasthenozoospermia by improving sperm mitochondrial membrane potential and restoring sperm mitochondrial ultrastructure.Keywords: traditional Chinese medicine, oligoasthenozoospermia, semen quality, mitochondrial membrane potential, mitochondrial ultrastructur
Propofol Inhibits Lipopolysaccharide-Induced Tumor Necrosis Factor-Alpha Expression and Myocardial Depression through Decreasing the Generation of Superoxide Anion in Cardiomyocytes
TNF-α has been shown to be a major factor responsible for myocardial depression in sepsis. The aim of this study was to investigate the effect of an anesthetic, propofol, on TNF-α expression in cardiomyocytes treated with LPS both in vivo and in vitro. In cultured cardiomyocytes, compared with control group, propofol significantly reduced protein expression of gp91phox and phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2) and p38 MAPK, which associates with reduced TNF-α production. In in vivo mice studies, propofol significantly improved myocardial depression and increased survival rate of mice after LPS treatment or during endotoxemia, which associates with reduced myocardial TNF-α production, gp91phox, ERK1/2, and p38 MAPK. It is concluded that propofol abrogates LPS-induced TNF-α production and alleviates cardiac depression through gp91phox/ERK1/2 or p38 MAPK signal pathway. These findings have great clinical importance in the application of propofol for patients enduring sepsis
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