537 research outputs found
Properties of Graphene: A Theoretical Perspective
In this review, we provide an in-depth description of the physics of
monolayer and bilayer graphene from a theorist's perspective. We discuss the
physical properties of graphene in an external magnetic field, reflecting the
chiral nature of the quasiparticles near the Dirac point with a Landau level at
zero energy. We address the unique integer quantum Hall effects, the role of
electron correlations, and the recent observation of the fractional quantum
Hall effect in the monolayer graphene. The quantum Hall effect in bilayer
graphene is fundamentally different from that of a monolayer, reflecting the
unique band structure of this system. The theory of transport in the absence of
an external magnetic field is discussed in detail, along with the role of
disorder studied in various theoretical models. We highlight the differences
and similarities between monolayer and bilayer graphene, and focus on
thermodynamic properties such as the compressibility, the plasmon spectra, the
weak localization correction, quantum Hall effect, and optical properties.
Confinement of electrons in graphene is nontrivial due to Klein tunneling. We
review various theoretical and experimental studies of quantum confined
structures made from graphene. The band structure of graphene nanoribbons and
the role of the sublattice symmetry, edge geometry and the size of the
nanoribbon on the electronic and magnetic properties are very active areas of
research, and a detailed review of these topics is presented. Also, the effects
of substrate interactions, adsorbed atoms, lattice defects and doping on the
band structure of finite-sized graphene systems are discussed. We also include
a brief description of graphane -- gapped material obtained from graphene by
attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic
Recent advances in the structural molecular biology of Ets transcription factors: interactions, interfaces and inhibition
The Ets family of eukaryotic transcription factors is based around the conserved Ets DNA-binding domain. Although their DNA-binding selectivity is biochemically and structurally well characterized, structures of homodimeric and ternary complexes point to Ets domains functioning as versatile protein-interaction modules. In the present paper, we review the progress made over the last decade to elucidate the structural mechanisms involved in modulation of DNA binding and protein partner selection during dimerization. We see that Ets domains, although conserved around a core architecture, have evolved to utilize a variety of interaction surfaces and binding mechanisms, reflecting Ets domains as dynamic interfaces for both DNA and protein interaction. Furthermore, we discuss recent advances in drug development for inhibition of Ets factors, and the roles structural biology can play in their future
216 Jewish Hospital of St. Louis
https://digitalcommons.wustl.edu/bjc_216/1137/thumbnail.jp
Ribosomal protein synthesis is not regulated at the translational level in Saccharomyces cerevisiae: balanced accumulation of ribosomal proteins L16 and rp59 is mediated by turnover of excess protein.
We have investigated the mechanisms whereby equimolar quantities of ribosomal proteins accumulate and assemble into ribosomes of the yeast Saccharomyces cerevisiae. Extra copies of the cry1 or RPL16 genes encoding ribosomal proteins rp59 or L16 were introduced into yeast by transformation. Excess cry1 or RPL16 mRNA accumulated in polyribosomes in these cells and was translated at wild-type rates into rp59 or L16 proteins. These excess proteins were degraded until their levels reached those of other ribosomal proteins. Identical results were obtained when the transcription of RPL16A was rapidly induced using GAL1-RPL16A promoter fusions, including a construct in which the entire RPL16A 5\u27-noncoding region was replaced with the GAL1 leader sequence. Our results indicate that posttranscriptional expression of the cry1 and RPL16 genes is regulated by turnover of excess proteins rather than autogenous regulation of mRNA splicing or translation. The turnover of excess rp59 or L16 is not affected directly by mutations that inactivate vacuolar hydrolases
Artificial graphenes: Dirac matter beyond condensed matter
After the discovery of graphene and its many fascinating properties, there
has been a growing interest for the study of "artificial graphenes". These are
totally different and novel systems which bear exciting similarities with
graphene. Among them are lattices of ultracold atoms, microwave or photonic
lattices, "molecular graphene" or new compounds like phosphorene. The advantage
of these structures is that they serve as new playgrounds for measuring and
testing physical phenomena which may not be reachable in graphene, in
particular: the possibility of controlling the existence of Dirac points (or
Dirac cones) existing in the electronic spectrum of graphene, of performing
interference experiments in reciprocal space, of probing geometrical properties
of the wave functions, of manipulating edge states, etc. These cones, which
describe the band structure in the vicinity of the two connected energy bands,
are characterized by a topological "charge". They can be moved in reciprocal
space by appropriate modification of external parameters (pressure, twist,
sliding, stress, etc.). They can be manipulated, created or suppressed under
the condition that the total topological charge be conserved. In this short
review, I discuss several aspects of the scenarios of merging or emergence of
Dirac points as well as the experimental investigations of these scenarios in
condensed matter and beyond.Comment: 16 pages, 26 figures. To appear in Comptes-rendus de l'Acad\'emie des
Sciences, Franc
Magneto-optical properties of multilayer graphenes
The magneto-optical absorption properties of graphene multilayers are
theoretically studied. It is shown that the spectrum can be decomposed into
sub-components effectively identical to the monolayer or bilayer graphene,
allowing us to understand the spectrum systematically as a function of the
layer number. Odd-layered graphenes always exhibit absorption peaks which
shifts in proportion to sqrt(B), with B being the magnetic field, due to the
existence of an effective monolayer-like subband. We propose a possibility of
observing the monolayer-like spectrum even in a mixture of multilayer graphene
films with various layers numbers.Comment: 9 pages, 7 figure
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