525 research outputs found
Actively controlling the topological transition of dispersion based on electrically controllable metamaterials
Topological transition of the iso-frequency contour (IFC) from a closed
ellipsoid to an open hyperboloid, will provide unique capabilities for
controlling the propagation of light. However, the ability to actively tune
these effects remains elusive and the related experimental observations are
highly desirable. Here, tunable electric IFC in periodic structure which is
composed of graphene/dielectric multilayers is investigated by tuning the
chemical potential of graphene layer. Specially, we present the actively
controlled transportation in two kinds of anisotropic zero-index media
containing PEC/PMC impurities. At last, by adding variable capacitance diodes
into two-dimensional transmission-line system, we present the experimental
demonstration of the actively controlled magnetic topological transition of
dispersion based on electrically controllable metamaterials. With the increase
of voltage, we measure the different emission patterns from a point source
inside the structure and observe the phase-transition process of IFCs. The
realization of actively tuned topological transition will opens up a new avenue
in the dynamical control of metamaterials.Comment: 21 pages,8 figure
Epigenetic Regulation of Hepatitis B Virus Covalently Closed Circular DNA: Implications for Epigenetic Therapy against Chronic Hepatitis B
Hepatitis B virus (HBV) infection represents a significant public health burden worldwide. Although current therapeutics manage to control the disease progression, lifelong treatment and surveillance are required because drug resistance develops during treatment and reactivations frequently occur following medication cessation. Thus, the occurrence of hepatocellular carcinoma (HCC) is decreased but not eliminated. One major reason for the treatment failure is the inability to eradicate or inactivate the viral covalently closed circular DNA (cccDNA) which is a stable episomal form of viral genome decorated with host histones and non-histone proteins. Accumulating evidence suggests that epigenetic modifications of cccDNA contribute to viral replication and the outcome of chronic HBV infection. Here, we summarize the progress on HBV epigenetics research and the therapeutic implications for chronic HBV infection by learning from the epigenetic therapies for cancer and other viral diseases, which may open a new venue to cure the chronic hepatitis B
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