12 research outputs found
Engineering topological surface-states: HgS, HgSe and HgTe
Using density functional electronic structure calculations, we establish the
consequences of surface termination and modification on protected
surface-states of metacinnabar (beta-HgS). Whereas we find that the Dirac cone
is isotropic and well-separated from the valence band for the (110) surface, it
is highly anisotropic at the pure (001) surface. We demonstrate that the
anisotropy is modified by surface passivation because the topological
surface-states include contributions from dangling bonds. Such dangling bonds
exist on all pure surfaces within the whole class HgX with X = S, Se, or Te and
directly affect the properties of the Dirac cone. Surface modifications also
alter the spatial location (depth and decay length) of the topologically
protected edge-states which renders them essential for the interpretation of
photoemission data.Comment: 5 pages, 4 figure
Metacinnabar ({\beta}-HgS): a strong 3D topological insulator with highly anisotropic surface states
We establish the presence of topologically protected edge states on the (001)
surface of HgS in the zinc-blende structure using density-functional electronic
structure calculations. The Dirac point of the edge state cone is very close to
the bulk valence band maximum. The Dirac cone is extremely anisotropic with a
very large electron velocity along one diagonal of the surface elementary cell
x' and a nearly flat dispersion in the perpendicular direction y'. The strong
anisotropy originates from a broken fourfold rotoinversion symmetry at the
surface.Comment: Phys. Rev. Lett., in pres
Decentralized Energy Systems, Market Integration, Optimization
In this study we develop a flexible modeling toolbox for decentralized electricity systems with an agent-based simulation approach at its core. Two RES-E generation models for wind and PV each with a high temporal and spatial resolution are presented and approaches to model specific aspects of the demand side in detail are introduced. The implementation of an AC load flow algorithm is described and the concept of a market-based congestion management mechanism is outlined
Semen inhibits Zika virus infection of cells and tissues from the anogenital region
Zika virus (ZIKV) causes severe birth defects and can be transmitted via sexual intercourse. Semen from ZIKV-infected individuals contains high viral loads and may therefore serve as an important vector for virus transmission. Here we analyze the effect of semen on ZIKV infection of cells and tissues derived from the anogenital region. ZIKV replicates in all analyzed cell lines, primary cells, and endometrial or vaginal tissues. However, in the presence of semen, infection by ZIKV and other flaviviruses is potently inhibited. We show that semen prevents ZIKV attachment to target cells, and that an extracellular vesicle preparation from semen is responsible for this anti-ZIKV activity. Our findings suggest that ZIKV transmission is limited by semen. As such, semen appears to serve as a protector against sexual ZIKV transmission, despite the availability of highly susceptible cells in the anogenital tract and high viral loads in this bodily fluid.Peer reviewe
Supramolecular Peptide Nanofibrils with Optimized Sequences and Molecular Structures for Efficient Retroviral Transduction
Amyloid-like peptide nanofibrils (PNFs) are abundant in nature providing rich bioactivities and playing both functional and pathological roles. The structural features responsible for their unique bioactivities are, however, still elusive. Supramolecular nanostructures are notoriously challenging to optimize, as sequence changes affect self-assembly, fibril morphologies and biorecognition. Herein, we report the first sequence optimization of PNFs for enhanced retroviral gene transduction via a multiparameter and a multiscale approach. Retroviral gene transfer is the method of choice for stable delivery of genetic information into cells offering great perspectives for the treatment of genetic disorders. Single fibril imaging, zeta potential, vibrational spectroscopy and quantitative retroviral transduction assays provided the structure parameters responsible for PNF assembly, fibril morphologies and PNF-virus-cell interactions. Optimized peptide sequences have been obtained quantitatively forming supramolecular nanofibrils with high intermolecular beta-sheet content that efficiently bound virions and attached to cellular membranes revealing efficient retroviral gene transfe
Supramolecular peptide nanofibrils with optimized sequences and molecular structures for efficient retroviral transduction
Amyloidâlike peptide nanofibrils (PNFs) are abundant in nature providing rich bioactivities and playing both functional and pathological roles. The structural features responsible for their unique bioactivities are, however, still elusive. Supramolecular nanostructures are notoriously challenging to optimize, as sequence changes affect selfâassembly, fibril morphologies, and biorecognition. Herein, the first sequence optimization of PNFs, derived from the peptide enhancing factorâC (EFâC, QCKIKQIINMWQ), for enhanced retroviral gene transduction via a multiparameter and a multiscale approach is reported. Retroviral gene transfer is the method of choice for the stable delivery of genetic information into cells offering great perspectives for the treatment of genetic disorders. Single fibril imaging, zeta potential, vibrational spectroscopy, and quantitative retroviral transduction assays provide the structure parameters responsible for PNF assembly, fibrils morphology, secondary and quaternary structure, and PNFâvirusâcell interactions. Optimized peptide sequences such as the 7âmer, CKFKFQF, have been obtained quantitatively forming supramolecular nanofibrils with high intermolecular ÎČâsheet content that efficiently bind virions and attach to cellular membranes revealing efficient retroviral gene transfer.<br/