1,729 research outputs found
Circular dichroism of magneto-phonon resonance in doped graphene
Polarization resolved, Raman scattering response due to E phonon in
monolayer graphene has been investigated in magnetic fields up to 29 T. The
hybridization of the E phonon with only the fundamental inter Landau
level excitation (involving the n=0 Landau level) is observed and only in one
of the two configurations of the circularly crossed polarized excitation and
scattered light. This polarization anisotropy of the magneto-phonon resonance
is shown to be inherent to relatively strongly doped graphene samples, with
carrier concentration typical for graphene deposited on SiO
Epitaxial Synthesis of Blue Phosphorene
Phosphorene is a new two-dimensional material composed of a single or few
atomic layers of black phosphorus. Phosphorene has both an intrinsic tunable
direct band gap and high carrier mobility values, which make it suitable for a
large variety of optical and electronic devices. However, the synthesis of
single-layer phosphorene is a major challenge. The standard procedure to obtain
phosphorene is by exfoliation. More recently, the epitaxial growth of
single-layer phosphorene on Au(111) has been investigated by molecular beam
epitaxy and the obtained structure has been described as a blue-phosphorene
sheet. In the present study, large areas of high-quality monolayer phosphorene,
with a band gap value at least equal to 0.8 eV, have been synthesized on
Au(111). Our experimental investigations, coupled with DFT calculations, give
evidence of two distinct phases of blue phosphorene on Au(111), instead of one
as previously reported, and their atomic structures have been determined.Comment: This paper reports on the epitaxial synthesis of blue phosphoren
Characterisation of a new VUV beamline at the Daresbury SRS using a dispersed fluorescence apparatus incorporating CCD detection
The design and performance of a new normal incidence monochromator at the Daresbury Synchrotron Radiation Source, optimised for experiments requiring high flux of vacuum-UV radiation, are described. The re-developed beamline 3.1, based on the Wadsworth design of monochromator, is the source of tunable vacuum-UV photons in the range 4 – 31 eV, providing over two orders of magnitude more flux than the vacuum-UV, Seya monochromator in its previous manifestation. The undispersed and dispersed fluorescence spectra resulting from photoexcitation of N, CO, CF and CF are presented. Emitting species observed were N B - X, CO Aď€ - Xď€ and Bď€ - Xď€, CF Cď€T - Xď€T and Cď€T - Aď€T, CF* A - A, and CF Bď€A - Xď€E. A CCD multi-channel detector has significantly reduced the time period needed to record dispersed fluorescence spectra with a comparable signal-to-noise ratio
The microdistribution of isoenzymic strains of Trypanosoma cruzi in southern Bolivia : new isoenzyme profiles and further arguments against Mendelian sexuality
Fluorescent oxide nanoparticles adapted to active tips for near-field optics
We present a new kind of fluorescent oxide nanoparticles with properties well
suited to active-tip based near-field optics. These particles with an average
diameter in the range 5-10 nm are produced by Low Energy Cluster Beam
Deposition (LECBD) from a YAG:Ce3+ target. They are studied by transmission
electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), classical
photoluminescence, cathodoluminescence and near-field scanning optical
microscopy (NSOM). Particles of extreme photo-stability as small as 10 nm in
size are observed. These emitters are validated as building blocks of active
NSOM tips by coating a standard optical tip with a 10 nm thick layer of
YAG:Ce3+ particles directly in the LECBD reactor and by subsequently performing
NSOM imaging of test surfaces.Comment: Changes made following Referee's comments; added references; one
added figure. See story on this article at:
http://nanotechweb.org/cws/article/tech/3606
Capturing multiple social perspectives on adaptation across scales:a Q-method analysis of actors from development planning in the Philippines
Drug resistance and treatment failure in leishmaniasis: A 21st century challenge
Reevaluation of treatment guidelines for Old and New World leishmaniasis is urgently needed on a global basis because treatment failure is an increasing problem. Drug resistance is a fundamental determinant of treatment failure, although other factors also contribute to this phenomenon, including the global HIV/AIDS epidemic with its accompanying impact on the immune system. Pentavalent antimonials have been used successfully worldwide for the treatment of leishmaniasis since the first half of the 20th century, but the last 10 to 20 years have witnessed an increase in clinical resistance, e.g., in North Bihar in India. In this review, we discuss the meaning of “resistance” related to leishmaniasis and discuss its molecular epidemiology, particularly for Leishmania donovani that causes visceral leishmaniasis. We also discuss how resistance can affect drug combination therapies. Molecular mechanisms known to contribute to resistance to antimonials, amphotericin B, and miltefosine are also outlined
STM topography and manipulation of single Au atoms on Si(100)
The low-temperature (12 K) adsorption of single Au atoms on Si(100) is studied by scanning tunneling microscopy (STM). Comparison between experimental and calculated STM topographies as well as density-functional-theory calculations of the adsorption energies enable us to identify two adsorption configurations of Au atoms between Si-dimer rows (BDRs) and on top of Si-dimer rows (TDRs). In both adsorption configurations, the Au atoms are covalently bound to two Si atoms through a partial electron transfer from Si to Au. STM manipulation confirms that the TDR adsorption configuration is metastable, whereas the BDR one is the most stable configuration.Peer reviewe
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