971 research outputs found
Electrochemical doping of few layer ZrNCl from first-principles: electronic and structural properties in field-effect configuration
We develop a first-principles theoretical approach to doping in field-effect
devices. The method allows for calculation of the electronic structure as well
as complete structural relaxation in field-effect configuration using
density-functional theory. We apply our approach to ionic-liquid-based
field-effect doping of monolayer, bilayer, and trilayer ZrNCl and analyze in
detail the structural changes induced by the electric field. We show that,
contrary to what is assumed in previous experimental works, only one ZrNCl
layer is electrochemically doped and that this induces large structural changes
within the layer. Surprisingly, despite these structural and electronic
changes, the density of states at the Fermi energy is independent of the
doping. Our findings imply a substantial revision of the phase diagram of
electrochemically doped ZrNCl and elucidate crucial differences with
superconductivity in Li intercalated bulk ZrNCl.Comment: 15 pages, 14 figure
HLA-Associated viral mutations are common in human immunodeficiency virus type 1 elite controllers
Elite controllers (EC) of human immunodeficiency virus type 1 (HTV-1) maintain viremia below the limit of detection without antiretroviral treatment. Virus-specific cytotoxic CD8+ T lymphocytes are believed to play a crucial role in viral containment, but the degree of immune imprinting and compensatory mutations in EC is unclear. We obtained plasma gag, pol, and nef sequences from HLA-diverse subjects and found that 30 to 40% of the predefined HLA-associated polymorphic sites show evidence of immune selection pressure in EC., compared to approximately 50% of the sites in chronic progressors. These data indicate ongoing viral replication and escape from cytotoxic T lymphocytes are present even in strictly controlled HTV-1 infection
Funneling and spin-orbit coupling in transition-metal dichalcogenide nanotubes and wrinkles
Strain engineering provides a powerful means to tune the properties of
two-dimensional materials. Accordingly, numerous studies have investigated the
effect of bi- and uniaxial strain. Yet, the strain fields in many systems such
as nanotubes and nanoscale wrinkles are intrinsically inhomogeneous and the
consequences of this symmetry breaking are much less studied. Understanding how
this affects the electronic properties is crucial especially since wrinkling is
a powerful method to apply strain to two-dimensional materials in a controlled
manner. In this paper, we employ density functional theory to understand the
correlation between the atomic and the electronic structure in nanoscale
wrinkles and nanotubes of the prototypical transition metal dichalcogenide
. Our research shows that the symmetry breaking in these
structures leads to strong Rashba-like splitting of the bands at the
point and they thus may be utilized in future tunable spintronic devices. The
inhomogeneous strain reduces the band gap and leads to a localization of the
band edges in the highest-curvature region, thus funneling excitons there.
Moreover, we show how wrinkles can be modeled as nanotubes with the same
curvature and when this comparison breaks down and further inhomogenities have
to be taken into account.Comment: main text 27 pages (preprint style) with 10 figures, attached
supplemental material 31 pages (58 in total) with 24 figure
Momentum-Resolved View of Electron-Phonon Coupling in Multilayer WSe
We investigate the interactions of photoexcited carriers with lattice
vibrations in thin films of the layered transition metal dichalcogenide (TMDC)
WSe. Employing femtosecond electron diffraction with monocrystalline
samples and first principle density functional theory calculations, we obtain a
momentum-resolved picture of the energy-transfer from excited electrons to
phonons. The measured momentum-dependent phonon population dynamics are
compared to first principle calculations of the phonon linewidth and can be
rationalized in terms of electronic phase-space arguments. The relaxation of
excited states in the conduction band is dominated by intervalley scattering
between valleys and the emission of zone-boundary phonons.
Transiently, the momentum-dependent electron-phonon coupling leads to a
non-thermal phonon distribution, which, on longer timescales, relaxes to a
thermal distribution via electron-phonon and phonon-phonon collisions. Our
results constitute a basis for monitoring and predicting out of equilibrium
electrical and thermal transport properties for nanoscale applications of
TMDCs
La Révolution comme retour à la tradition — stratégies discursives des libéraux dans les Cortès de Cadix, 1810—1813
Der Diskurs der spanischen Liberalen konstituierte sich im wesentlichen in den politischen
Auseinandersetzungen in den Cortes (1810—1813) und der Presse von Cadiz und
wurde von Themen getragen, die bereits die Aufklärung und Französische Revolution beherrschten.
Dabei entwickelten die Liberalen zwei grundlegende Diskursstrategien. Einerseits
übernahmen sie die Sprache der Revolution (z. B. „Libertad“ ). Andererseits suchten
sie sich gegen den französischen Sprachgebrauch und damit den ihrer Feinde im Unabhängigkeitskrieg
(1808—1814) abzugrenzen (z. B. Ablehnung von „revolución“ ) und orientierten
sich an mittelalterlichen Traditionen, dio ihnen auch Bezeichnungen für neue Institutionen
und Errungenschaften lieferten (z. B. „Cortes“ )
P09-11. Reduced replication capacity of NL4-3 chimeric viruses encoding RT-Integrase sequences from HIV-1 elite controllers
Background: Spontaneous control of HIV to 0.05). Viruses derived from HLA-B57+ EC (N = 20) appeared to replicate slower than those from B57+ progressors (N = 8) (p = 0.004). Similar results were observed between B51+ EC (N = 4) and B51+ progressors (N = 10) (p = 0.024), but not between B27+ EC (N = 9) and B27+ progressors (N = 5) (p = 0.437). Conclusion: This study extends previous observations for Gag and demonstrates that Pol variants from EC also display reduced function. The association between fitness and expression of certain HLA that present Pol epitopes suggests that immune-mediated mutations impairing viral fitness may play a key role in spontaneous control of HIV. Results indicate that HLA alleles responsible for such defects in protein function may differ among viral genes. Further identification of HLA-associated changes in HIV may allow design of vaccines targeting the most vulnerable regions of the virus
Charakterisierung der Virulenzfaktoren invC und sseD des Typ III-Sekretionssystems von Salmonella Typhimurium DT104 mittels ex vivo-Zytokin-Expression im experimentell infizierten Schwein
Charakterisierung der Virulenzfaktoren invC und sseD des Typ III-Sekretionssystems von Salmonella Typhimurium DT104 mittels ex vivo-Zytokin-Expression im experimentell infizierten Schwei
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