53 research outputs found
Effects of probiotic Bacillus as a substitute for antibiotics on antioxidant capacity and intestinal autophagy of piglets
Barrier Inhomogeneity of Schottky Diode on Nonpolar AlN Grown by Physical Vapor Transport
An aluminum nitride (AlN) Schottky barrier diode (SBD) was fabricated on a
nonpolar AlN crystal grown on tungsten substrate by physical vapor transport.
The Ni/Au-AlN SBD features a low ideality factor n of 3.3 and an effective
Schottky barrier height (SBH) of 1.05 eV at room temperature. The ideality
factor n decreases and the effective SBH increases at high temperatures. The
temperature dependences of n and SBH were explained using an inhomogeneous
model. A mean SBH of 2.105 eV was obtained for the Ni-AlN Schottky junction
from the inhomogeneity analysis of the current-voltage characteristics. An
equation in which the parameters have explicit physical meanings in thermionic
emission theory is proposed to describe the current-voltage characteristics of
inhomogeneous SBDs.Comment: 6 pages, 6 figure
Quantum geometric-induced third-order nonlinear transport in antiferromagnetic topological insulator MnBi2Te4
Discovering the nonlinear transport features in antiferromagnets is of
fundamental interest in condensed matter physics as it offers a new frontier of
the understanding deep connections between multiple degrees of freedom,
including magnetic orders, symmetries, and band geometric properties.
Antiferromagnetic topological insulator MnBiTe has provided a
highly tunable platform for experimental explorations due to its rich magnetic
structures and striking topological band structures. Here, we experimentally
investigate the third-order nonlinear transport properties in bulk
MnBiTe flakes. The measured third-harmonic longitudinal
() and transverse () voltages show
intimate connection with magnetic transitions of MnBiTe flakes and
their magnitudes change abruptly as MnBiTe flakes go through
magnetic transitions with varying temperature and magnetic fields. In addition,
the measured exhibits an even-symmetric feature with
changing magnetic field direction and the shows an
odd-symmetric property, which are believed to be related to the quantum metric
and the emergency of non-zero Berry curvature quadrupole with broken
symmetry and non-degenerate band structures under external magnetic fields,
respectively. Our work shows great advances in the understanding of the
underlying interactions between multiple geometric quantities
Glycyrrhizic Acid Promotes M1 Macrophage Polarization in Murine Bone Marrow-Derived Macrophages Associated with the Activation of JNK and NF- κ
First Principles Study on Li-doped and Li,O-codoped AlN
This paper focuses on the detailed investigation of the structural and electronic properties of wurtzite AlN crystals doped by Li with and without oxygen with the first principles calculation. All the calculations have exhibited significant structural distortions. Compared with the monoclinic doping, the oxygen codoping has improved the structure deformation and lowered the formation energy of Li dopants. The calculated electronic density of states (DOS) reveals that all doping configurations still preserve semiconductor characteristics. The states around the valence band maximum cross the Fermi level, which implies p-type doping. The induced extra levels are extremely localized and flat in Li-doped AlN while much more delocalized in oxygen codoped models. The mono-doping of Li is in general energetically unfavorable while the codoping improves the formation and makes the intercalation of Li more stable in AlN. According to the results, the codoping configuration of Li with O in AlN has provided a useful way of modifying the corresponding properties
Tunable interaction-induced localization of surface electrons in antidot nanostructured Bi2Te3 thin films
Recently, a logarithmic decrease of conductivity has been observed in
topological insulators at low temperatures, implying a tendency of localization
of surface electrons. Here, we report quantum transport experiments on the
topological insulator Bi2Te3 thin films with arrayed antidot nanostructures.
With increasing density of the antidots, a systematic decrease is observed in
the slope of the logarithmic temperature-dependent conductivity curves,
indicating the electron-electron interaction can be tuned by the antidots.
Meanwhile, the weak anti-localization effect revealed in magnetoconductivity
exhibits an enhanced dominance of electron-electron interaction among
decoherence mechanisms. The observation can be understood from an
antidot-induced reduction of the effective dielectric constant, which controls
the interactions between the surface electrons. Our results clarify the
indispensable role of the electron-electron interaction in the localization of
surface electrons and indicate the localization of surface electrons in an
interacting topological insulator.Comment: 27 pages, article+supplemental materials, published in ACS Nan
Glycyrrhizin Attenuates Salmonella enterica Serovar Typhimurium Infection: New Insights Into Its Protective Mechanism
Glycyrrhizin (GL), a triterpenoid glycoside, serves important functions in various biological activities, including antiviral and antitumor immune responses. However, the anti-inflammatory effects of GL on Salmonella enterica serovar Typhimurium (ST)-induced injury in mice and the mechanisms underlying the protection of GL are poorly understood. Here, we investigated the effects of GL on host immune responses against ST infection in mice. A phenotypic analysis using hematoxylin and eosin (H&E) staining and transmission electron microscopy showed that GL relieved ST-induced weight loss and intestinal mucosal injury. A colonization assay showed that GL significantly reduced ST colonization in the ileum and colon and translocation to the liver and spleen. An antibacterial activity assay and real-time PCR revealed that GL had no direct inhibitory impact on ST growth or virulence gene expression. ELISA showed that GL pretreatment significantly decreased proinflammatory cytokine (IFN-γ, TNF-α, IL-6) secretion and increased anti-inflammatory cytokine (IL-10) secretion in the ileum, colon and serum of ST-infected mice. Moreover, flora analysis showed that GL reduced Akkermansia, Sutterella, Prevotella and Coprococcus but enriched Parabacteroides and Anaerotruncus in the cecum of ST-infected mice. These results suggest that GL promotes the secretion of immune factors and modulates intestinal flora to prevent further ST infection. We also analyzed the effect of GL on immunocytes and found that GL promoted the phenotypic and functional maturation of murine bone marrow-derived dendritic cells (BMDCs). Flow cytometry and western blotting demonstrated that NF-κB, ERK, and p38 MAPK were required for GL-induced BMDC maturation. The above findings indicate that GL attenuates ST infection by modulating immune function and intestinal flora. This study enriches our current knowledge of GL-mediated immunological function and provides a new perspective on the prevention of Salmonella infection in animals and humans
Bacillus amyloliquefaciens SC06 Protects Mice Against High-Fat Diet-Induced Obesity and Liver Injury via Regulating Host Metabolism and Gut Microbiota
Obesity and the related liver diseases are prevalent around the world. Although probiotics have been shown to prevent obesity through multiple ways, only few researches investigated the lipid-lowering effects of probiotic Bacillus. Moreover, the limited results consistently suggested that Bacillus regulated genes related to lipogenesis and oxidation, but no further exploration was made. Our previous study revealed that Bacillus amyloliquefaciens SC06 has a potent antioxidant capacity in vitro. The aim of this study is to investigate the effects of SC06 on obesity and the associated liver injury of high-fat diet (HFD)-fed-mice and its underlying mechanism. By feeding normal chow (NC), NC+SC06, HFD, and HFD+SC06 to mice, we found that SC06 improved body weight gain, hepatic steatosis, and glucose metabolism of HFD-mice. Furthermore, SC06 also increased the antioxidant capacity of mice through Nrf2/Keap1 signaling pathway. High-throughput sequencing of 16S rRNA gene showed that HFD changed the gut microbiota dramatically, while HFD+SC06 decreased the ratio of Firmicutes/Bacteroidetes and increased TM7 abundance. More differences were also found in lower taxa. Altogether, SC06 is a potential probiotic that decreases HFD-related lipid accumulation and liver injury via regulating the antioxidant capacity and host gut microbiota
Magnetotransport and optoelectronic characterizations of AlGaN/GaN heterostructures
Fluorine plasma (F-plasma) treatment technique can effectively incorporate F-atoms into the AlGaN barrier, depleting the two-dimensional electron gases (2DEG) in AlGaN/GaN high electron mobility transistors (HEMT) and converting the device from depletion-mode to enhancement-mode. In this thesis, the effects of F-plasma treatment on the transport and optoelectronic properties of AlGaN/GaN heterostructures were studied. It was found that the F-related centers were deep electron traps, which dominated the 2DEG scattering mechanism in F-plasma treated AlGaN/GaN heterostructures. Gated Hall measurements revealed that both 2DEG density and mobility increased when positive gate voltage was applied. It was obtained that the photoionization energy of the F-related centers was about 1.85 eV, while the energy barrier for electron recapture by F-related centers was determined to be 0.624 eV. The configuration-coordinate diagram of F-related centers in AlGaN/GaN heterostructure was obtained. The effects of F-plasma treatment on the performance of AlGaN/GaN heterostructure based UV-photodetectors were also investigated. Transport behaviors of the Ni/Au-AlGaN/GaN Schottky diodes in bias range far beyond the turn-on voltage were studied for the first time. A second turn-on was observed in the current-voltage (I-V) characteristics. Electroluminescence (EL) corresponding to the bandedge emission from GaN layer was detected when applied bias was larger than the second turn-on voltage, indicating that the second turn-on in the I-V characteristics was due to the hole injection into GaN layer. A model based on the Fermi level depinning due to the interface states ionization by hot electrons was proposed to explain the observed second turn-on in transport behaviors and the corresponding electroluminescence characteristics. The effects of F-plasma treatment on the transport as well as the EL behaviors of the Ni/Au-AlGaN/GaN Schottky diode were also investigated. It was found that the F-related deep centers in AlGaN barrier could assist the hole injection processes through hopping conduction
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