7,248 research outputs found
Mo(SxOy) thin films deposited by electrochemistry for application in organic photovoltaic cells
In this study, Mo(SxOy) thin films were deposited onto fluorine doped tin oxide (FTO) using pulsed electrochemical deposition method. It is shown by scanning electron microscopy, energy-dispersive spectroscopy and X-ray photoelectron spectroscopy that after water cleaning the deposited Mo(SxOy) film corresponds to a hybrid layer MoSx:MoO3. This hybrid is used as anode buffer layer (ABL) in planar organic photovoltaic cells (OPVCs) based on the couple copper-phthalocyanine/fullerene. It is shown that it is necessary to proceed to a soft annealing-5 min at 150 °C- of the anode FTO/Mo(SxOy) to clean the ABL surface in order to obtain efficient contact with the organic material. The OPVC with the optimum Mo(SxOy) thickness, 12 nm, showed a power conversion efficiency, PCE = 1.41% under an illumination of AM1.5, which is 12% higher than that achieved with a simple MoO3 ABL. This improvement is attributed to the fact that using a hybrid MoS2:MoO3 ABL allows to combine the advantages of its both constituents. The MoSx blocks the electrons, while the high work function of MoO3 induces a high hole extraction efficiency at the interface electron donor/anode
Shear viscosity of hot scalar field theory in the real-time formalism
Within the closed time path formalism a general nonperturbative expression is
derived which resums through the Bethe-Salpter equation all leading order
contributions to the shear viscosity in hot scalar field theory. Using a
previously derived generalized fluctuation-dissipation theorem for nonlinear
response functions in the real-time formalism, it is shown that the
Bethe-Salpeter equation decouples in the so-called (r,a) basis. The general
result is applied to scalar field theory with pure lambda*phi**4 and mixed
g*phi**3+lambda*phi**4 interactions. In both cases our calculation confirms the
leading order expression for the shear viscosity previously obtained in the
imaginary time formalism.Comment: Expanded introduction and conclusions. Several references and a
footnote added. Fig.5 and its discussion in the text modified to avoid double
counting. Signs in Eqs. (45) and (53) correcte
Physics of the Muon Spectrometer of the ALICE Experiment
The main goal of the Muon spectrometer of the ALICE experiment at LHC is the
measurement of heavy quark production in p+p, p+A and A+A collisions at LHC
energies, via the muonic channel. Physics motivations and expected performances
have been presented in this talk.Comment: 10 pages and 4 figures. Talk presented in the ICPAQGP Conference,
February 8-12, 2005, Salt Lake City, Kolkata, India. Web page of the
conference : http://www.veccal.ernet.in/~icpaqgp
Experimental validation of Lyot stop apodization in ground-based coronagraphy
ABSTRACT We show that the use of apodizing functions at the coronagraph Lyot plane may be useful for improving the image contrast of ground-based coronagraphs. An experimental set-up consisting of a tip–tilt mirror, a coronagraph and a low-noiseEMCCDcamerawas implemented at theWilliam Herschel Telescope. Images were taken in the I band, which meant that the D/r0 value was around 10. Experimental results confirm that, for moderately aberrated wavefronts, our instrument works as theoretically expected, and that the contrast value attained is high enough to provide direct detection of faint companions.This research was supported by the Ministerio de EconomĂa y Competitividad
under project FIS2012-31079 and the FundaciĂłn SĂ©neca
of Murcia under projects 15419/PI/10 and 15345/PI/10
HIV/antiretroviral therapy–related lipodystrophy syndrome (HALS) is associated with higher RBP4 and lower omentin in plasma
AbstractVery little information is available on the involvement of newly characterized adipokines in human immunodeficiency virus (HIV)/antiretroviral therapy (ART)-associated lipodystrophy syndrome (HALS). Our aim was to determine whether apelin, apelin receptor, omentin, RBP4, vaspin and visfatin genetic variants and plasma levels are associated with HALS. We performed a cross-sectional multicentre study that involved 558 HIV type 1–infected patients treated with a stable highly active ART regimen, 240 of which had overt HALS and 318 who did not have HALS. Epidemiologic and clinical variables were determined. Polymorphisms in the apelin, omentin, RBP4, vaspin and visfatin genes were assessed by genotyping. Plasma apelin, apelin receptor, omentin, RBP4, vaspin and visfatin levels were determined by enzyme-linked immunosorbent assay in 163 patients (81 with HALS and 82 without HALS) from whom stored plasma samples were available. Student's t test, one-way ANOVA, chi-square test, Pearson and Spearman correlations and linear regression analysis were used for statistical analyses. There were no associations between the different polymorphisms assessed and the HALS phenotype. Circulating RBP4 was significantly higher (p < 0.001) and plasma omentin was significantly lower (p 0.001) in patients with HALS compared to those without HALS; differences in plasma levels of the remaining adipokines were nonsignificant between groups. Circulating RBP4 concentration was predicted independently by the presence of HALS. Apelin and apelin receptor levels were independently predicted by body mass index. Visfatin concentration was predicted independently by the presence of acquired immunodeficiency syndrome. HALS is associated with higher RBP4 and lower omentin in plasma. These two adipokines, particularly RBP4, may be a link between HIV/ART and fat redistribution syndromes
Morphological Study and Dielectric Behavior of Nonisothermally Crystallized Poly(ethylene naphthalate) Nanocomposites as a Function of Graphene Content
Morphological evolution and dielectric properties of poly(ethylene naphthalate)- (PEN-) graphene nanocomposites nonisothermally crystallized have been investigated. PEN-graphene nanocomposites containing 0.01, 0.025, 0.05, 0.075, and 0.1 wt% of graphene were prepared by melt blending in a mini twin screw extruder. The results showed that graphene exhibited a superior influence on morphological and conformational structure of PEN during nonisothermal crystallization at low graphene contents. Crystallization temperature (Tc) was found to be increased up to 18°C supporting the high nucleating activity of graphene layers. Wide angle X-ray diffraction (WAXD) and Fourier Transform Infrared Spectroscopy (FTIR) indicated that graphene modifies the conformation of PEN chains promoting crystallinity and favoring the evolution from α to β crystalline form with homogeneous lamellar thickness. It may be attributed to the structural similarity between naphthalene rings and graphene structure and to π-π interactions during nucleation. Dielectric behavior was found to be a function of graphene content where the nanocomposites changed from dielectric to low conducting material when passing from 0.075 to 0.1 wt% of graphene content. This phenomenon permits having a wide range of properties to fit a wide variety of applications required to store electrical energy of low voltage
Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions
This report reviews the study of open heavy-flavour and quarkonium production
in high-energy hadronic collisions, as tools to investigate fundamental aspects
of Quantum Chromodynamics, from the proton and nucleus structure at high energy
to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is
given to the lessons learnt from LHC Run 1 results, which are reviewed in a
global picture with the results from SPS and RHIC at lower energies, as well as
to the questions to be addressed in the future. The report covers heavy flavour
and quarkonium production in proton-proton, proton-nucleus and nucleus-nucleus
collisions. This includes discussion of the effects of hot and cold strongly
interacting matter, quarkonium photo-production in nucleus-nucleus collisions
and perspectives on the study of heavy flavour and quarkonium with upgrades of
existing experiments and new experiments. The report results from the activity
of the SaporeGravis network of the I3 Hadron Physics programme of the European
Union 7th Framework Programme
Non-standard interactions versus non-unitary lepton flavor mixing at a neutrino factory
The impact of heavy mediators on neutrino oscillations is typically described
by non-standard four-fermion interactions (NSIs) or non-unitarity (NU). We
focus on leptonic dimension-six effective operators which do not produce
charged lepton flavor violation. These operators lead to particular
correlations among neutrino production, propagation, and detection non-standard
effects. We point out that these NSIs and NU phenomenologically lead, in fact,
to very similar effects for a neutrino factory, for completely different
fundamental reasons. We discuss how the parameters and probabilities are
related in this case, and compare the sensitivities. We demonstrate that the
NSIs and NU can, in principle, be distinguished for large enough effects at the
example of non-standard effects in the --sector, which basically
corresponds to differentiating between scalars and fermions as heavy mediators
as leading order effect. However, we find that a near detector at superbeams
could provide very synergistic information, since the correlation between
source and matter NSIs is broken for hadronic neutrino production, while NU is
a fundamental effect present at any experiment.Comment: 32 pages, 5 figures. Final version published in JHEP. v3: Typo in Eq.
(27) correcte
Quarkonium production in high energy proton-proton and proton-nucleus collisions
We present a brief overview of the most relevant current issues related to
quarkonium production in high energy proton-proton and proton-nucleus
collisions along with some perspectives. After reviewing recent experimental
and theoretical results on quarkonium production in pp and pA collisions, we
discuss the emerging field of polarisation studies. Thereafter, we report on
issues related to heavy-quark production, both in pp and pA collisions,
complemented by AA collisions. To put the work in a broader perspective, we
emphasize the need for new observables to investigate quarkonium production
mechanisms and reiterate the qualities that make quarkonia a unique tool for
many investigations in particle and nuclear physics.Comment: Overview for the proceedings of QUARKONIUM 2010: Three Days Of
Quarkonium Production in pp and pA Collisions, 29-31 July 2010, Palaiseau,
France; 34 pages, 30 figures, Late
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