1,151 research outputs found
Optoelectronic properties of triphenylamine based dyes for solar cell applications. A DFT study
Indexación: Scopus.GSM thanks to the Department of Chemistry at the Universidad Andres Bello, Concepcion, Chile. LHMH gratefully acknowledges financial support from CONACYT (Projects CB2015-257823) and to the Universidad Autónoma del Estado de Hidalgo.Dye-sensitized solar cells (DSSCs) based on triphenylamine (TPA) as a donor group linked with the acceptor cyanoacrylic acid electron acceptor by 2,2'-bithiophene as π-bridged (D-π-A) has been investigated by Density Functional Theory (DFT) at the B3LYP/6-311G(d,p) level of theory, to establish the conformational orientation of cyanoacrylic acid group as well as evaluate the effect of planarizing the 2,2'-bithiophene unit in position 3 and 3' by electron withdrawing or donor groups on the electronic structure properties of ground and doping(n,p) states. Also, the Time Dependent Density Functional Theory (TD-DFT) at the CPCM-TD-CAM-B3LYP//CAM-B3LYP/6-311G(d,p) level of theory were selected to modulate the electronic absorption spectra and charge-transfer capabilities of the molecules analyzed in the present work. The results indicate that adding an auxiliary donor or withdrawing group to the 2,2'-bithiophene in the (D-π-A) arrangement allow to modify the LUMO's energy of the dyes, while the HOMO's energy is slightly affected. © 2018 Sociedade Brasileira de Quimica. All rights reserved.http://quimicanova.sbq.org.br/imagebank/pdf/AR20170232.pd
Influence of shower fluctuations and primary composition on studies of the shower longitudinal development
We study the influence of shower fluctuations, and the possible presence of
different nuclear species in the primary cosmic ray spectrum, on the
experimental determination of both shower energy and the proton air inelastic
cross section from studies of the longitudinal development of atmospheric
showers in fluorescence experiments. We investigate the potential of track
length integral and shower size at maximum as estimators of shower energy. We
find that at very high energy (~10^19-10^20 eV) the error of the total energy
assignment is dominated by the dependence on the hadronic interaction model,
and is of the order of 5%. At lower energy (~10^17-10^18 eV), the uncertainty
of the energy determination due to the limited knowledge of the primary cosmic
ray composition is more important. The distribution of depth of shower maximum
is discussed as a measure of the proton-air cross section. Uncertainties in a
possible experimental measurement of this cross section introduced by intrinsic
shower fluctuations, the model of hadronic interactions, and the unknown
mixture of primary nuclei in the cosmic radiation are numerically evaluated.Comment: 12 pages, 11 figures, 4 table
Noncommutative Gauge Field Theories: A No-Go Theorem
Studying the general structure of the noncommutative (NC) local groups, we
prove a no-go theorem for NC gauge theories. According to this theorem, the
closure condition of the gauge algebra implies that: 1) the local NC
{\it algebra} only admits the irreducible n by n matrix-representation. Hence
the gauge fields are in n by n matrix form, while the matter fields {\it can
only be} in fundamental, adjoint or singlet states; 2) for any gauge group
consisting of several simple-group factors, the matter fields can transform
nontrivially under {\it at most two} NC group factors. In other words, the
matter fields cannot carry more than two NC gauge group charges. This no-go
theorem imposes strong restrictions on the NC version of the Standard Model and
in resolving the standing problem of charge quantization in noncommutative QED.Comment: latex, 4 page
Current status of bacterial spot of stone fruits and almond caused by Xanthomonas arboricola pv. pruni in Spain
In 2002, typical symptoms of bacterial spot disease of stone fruits caused by Xanthomomas arboricola pv. pruni (Xap) were observed for the first time on Japanese plum in Badajoz (south-western Spain). During the following years, the pathogen was found in seven other eastern and northern Spanish provinces (Valencia, Alicante, Zaragoza, Huesca, Navarra, LĂ©rida and Mallorca) affecting different cultivars of Japanese plum, nectarine, peach and almond. There are few previous reports of Xap on almond, the Spanish outbreaks constituting its first detection on this host in the European Union (EU). Identification of the pathogen was performed using biochemical tests, fatty acid methyl esters (FAME) profiles, conventional and real-time PCR, and hypersensitivity reaction on tobacco leaves. Pathogenicity was demonstrated by inoculation of young potted plants of peach, plum or almond and successful re-isolations from plants with symptoms. In areas where infected plants were found, eradication programs were set up since Xap has a quarantine status according to phytosanitary EU legislation.Publishe
Time-Space Noncommutativity in Gravitational Quantum Well scenario
A novel approach to the analysis of the gravitational well problem from a
second quantised description has been discussed. The second quantised formalism
enables us to study the effect of time space noncommutativity in the
gravitational well scenario which is hitherto unavailable in the literature.
The corresponding first quantized theory reveals a leading order perturbation
term of noncommutative origin. Latest experimental findings are used to
estimate an upper bound on the time--space noncommutative parameter. Our
results are found to be consistent with the order of magnitude estimations of
other NC parameters reported earlier.Comment: 7 pages, revTe
Pair Production by a Constant External Field in Noncommutative QED
In this paper we study QED on the noncommutative space in the constant
electro-magnetic field background. Using the explicit solutions of the
noncommutative version of Dirac equation in such background, we show that there
are well-defined in and out -going asymptotic states and also there is a causal
Green's function. We calculate the pair production rate in this case. We show
that at tree level noncommutativity will not change the pair production and the
threshold electric field. We also calculate the pair production rate
considering the first loop corrections. In this case we show that the threshold
electric field is decreased by the noncommutativity effects.Comment: 11 pages, no figures, v3: minor changes with respect to v2, the
version to appear in PL
Detección de Xanthomonas arboricola pv. pruni mediante inmunocaptura magnética y PCR en tiempo real: póster
PublishedTrabajo financiado por el Instituto Nacional de InvestigaciĂłn y TecnologĂa Agraria y Alimentaria (INIA), proyecto RTA2011-00140-C03-02 y por la Red CYTED FRUT-SAN 112RT044
General structure of the photon self-energy in non-commutative QED
We study the behavior of the photon two point function, in non-commutative
QED, in a general covariant gauge and in arbitrary space-time dimensions. We
show, to all orders, that the photon self-energy is transverse. Using an
appropriate extension of the dimensional regularization method, we evaluate the
one-loop corrections, which show that the theory is renormalizable. We also
prove, to all orders, that the poles of the photon propagator are gauge
independent and briefly discuss some other related aspects.Comment: 16 pages, revtex4. This is the final version to be published in Phys.
Rev.
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