Pengjie Wang

Effects of annealing on the ferromagnetism and photoluminescence of Cu-doped ZnO nanowires

Room temperature ferromagnetic Cu-doped ZnO nanowires have been synthesized using the chemical vapor deposition method. By combining structural characterizations and comparative annealing experiments, it has been found that both extrinsic (CuO nanoparticles) and intrinsic (Zn(1-x)Cu(x)O nanowires) sources are responsible for the observed ferromagnetic ordering of the as-grown samples. As regards the former, annealing in Zn vapor led to a dramatic decrease of the ferromagnetism. For the latter, a reversible switching of the ferromagnetism was observed with sequential annealings in Zn vapor and oxygen ambience respectively, which agreed well with previous reports for Cu-doped ZnO films. In addition, we have for the first time observed low temperature photoluminescence changed with magnetic properties upon annealing in different conditions, which revealed the crucial role played by interstitial zinc in directly mediating high T(c) ferromagnetism and indirectly modulating the Cu-related structured green emission via different charge transfer transitions.

Observation of a Helical Luttinger-Liquid in InAs/GaSb Quantum Spin Hall Edges

We report on the observation of a helical Luttinger liquid in the edge of an InAs/GaSb quantum spin Hall insulator, which shows characteristic suppression of conductance at low temperature and low bias voltage. Moreover, the conductance shows power-law behavior as a function of temperature and bias voltage. The results underscore the strong electron-electron interaction effect in transport of InAs/GaSb edge states. Because of the fact that the Fermi velocity of the edge modes is controlled by gates, the Luttinger parameter can be fine tuned. Realization of a tunable Luttinger liquid offers a one-dimensional model system for future studies of predicted correlation effects.

Protein kinase D1 is essential for Ras-induced senescence and tumor suppression by regulating senescence-associated inflammation

Significance Oncogene-induced senescence (OIS) is an initial barrier for cancer development. Reactive oxygen species (ROS) play critical roles in oncogenic Ras OIS. Senescent cells develop a senescence-associated secretory phenotype (SASP), which has important role in tumor suppression and tissue repair. However, the mechanisms underlying the SASP regulation are not clear. In this paper, we show that ROS-protein kinase Cδ (PKCδ)-protein kinase D1 (PKD1) axis is essential for SASP induction and maintenance via modulation of NF-κB activity. Considering the pivotal role of both SASP and ROS in systemic aging and age-related diseases, the link between ROS-PKCδ-PKD1 pathway and SASP regulation elucidated here may provide a new target to intervene in age-related inflammation and diseases. Oncogene-induced senescence (OIS) is an initial barrier to tumor development. Reactive oxygen species (ROS) is critical for oncogenic Ras OIS, but the downstream effectors to mediate ROS signaling are still relatively elusive. Senescent cells develop a senescence-associated secretory phenotype (SASP). However, the mechanisms underlying the regulation of the SASP are largely unknown. Here, we identify protein kinase D1 (PKD1) as a downstream effector of ROS signaling to mediate Ras OIS and SASP. PKD1 is activated by oncogenic Ras expression and PKD1 promotes Ras OIS by mediating inflammatory cytokines interleukin-6 (IL-6) and interleukin-8 (IL-8) via modulation of NF-κB activity. We demonstrate that ROS-protein kinase Cδ (PKCδ)-PKD1 axis is essential for the establishment and maintenance of IL-6/IL8 induction. In addition, ablation of PKD1 causes the bypass of Ras OIS, and promotes cell transformation and tumorigenesis. Together, these findings uncover a previously unidentified role of ROS-PKCδ-PKD1 pathway in Ras OIS and SASP regulation.

Observation of quantum Griffiths singularity and ferromagnetism at the superconducting LaAl O 3 / SrTi O 3 ( 110 ) interface

Diverse phenomena emerge at the interface between band insulators

Competition between quantum fluctuations and antiferroelectric order in Ru-doped Sr0.8Ca0.2Ti1?xRuxO3

\mathrm{LaAl}{\mathrm{O}}_{3}

Competing ν = 5/2 fractional quantum Hall states in confined geometry

and

Low-temperature conductivity of weakly interacting quantum spin Hall edges in strained-layer InAs/GaInSb

\mathrm{SrTi}{\mathrm{O}}_{3}

Depinning transition of bubble phases in a high Landau level

, such as superconductivity and ferromagnetism, showing an opportunity for potential applications as well as contributing to fundamental research interests. Here, we report the superconductor-metal transition driven by a perpendicular magnetic field in superconducting two-dimensional electron gas formed at the

Nonlinear transport of graphene in the quantum Hall regime

\mathrm{LaAl}{\mathrm{O}}_{3}/\mathrm{SrTi}{\mathrm{O}}_{3}(110)

Stability of the 5/2 fractional quantum Hall state in a Corbino disc sample with in-plane electric fields

interface, which offers an appealing platform for quantum phase transition from a superconductor to a weakly localized metal. Interestingly, when approaching the quantum critical point, the dynamic critical exponent is not a constant but a diverging value, which is direct evidence of a quantum Griffiths singularity arising from quenched disorder at ultralow temperatures. Furthermore, the hysteretic property of magnetoresistance is observed at the