Effect of graphene substrate on the SERS Spectra of Aromatic bifunctional molecules on metal nanoparticles

The design of molecular sensors plays a very important role within nanotechnology and especially in the development of different devices for biomedical applications. Biosensors can be classified according to various criteria such as the type of interaction established between the recognition element and the analyte or the type of signal detection from the analyte (transduction). When Raman spectroscopy is used as an optical transduction technique the variations in the Raman signal due to the physical or chemical interaction between the analyte and the recognition element has to be detected. Therefore any significant improvement in the amplification of the optical sensor signal represents a breakthrough in the design of molecular sensors. In this sense, Surface-Enhanced Raman Spectroscopy (SERS) involves an enormous enhancement of the Raman signal from a molecule in the vicinity of a metal surface. The main objective of this work is to evaluate the effect of a monolayer of graphene oxide (GO) on the distribution of metal nanoparticles (NPs) and on the global SERS enhancement of paminothiophenol (pATP) and 4-mercaptobenzoic acid (4MBA) adsorbed on this substrate. These aromatic bifunctional molecules are able to interact to metal NPs and also they offer the possibility to link with biomolecules. Additionally by decorating Au or Ag NPs on graphene sheets, a coupled EM effect caused by the aggregation of the NPs and strong electronic interactions between Au or Ag NPs and the graphene sheets are considered to be responsible for the significantly enhanced Raman signal of the analytes [1-2]. Since there are increasing needs for methods to conduct reproducible and sensitive Raman measurements, Grapheneenhanced Raman Scattering (GERS) is emerging as an important method [3].Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Updated limits on visibly and invisibly decaying Higgs bosons from LEP

Talk presented at the XXIX Rencontres de Moriond, Electroweak Interactions and Unified Theories, March 12-19, 1994, MeribelTalk presented at the XXIX Rencontres de Moriond, Electroweak Interactions and Unified Theories, March 12-19, 1994, MeribelTalk presented at the XXIX Rencontres de Moriond, Electroweak Interactions and Unified Theories, March 12-19, 1994, Meribe

Composición briofítica de los hayedos de Navarra (España)

Se presenta un catálogo de 175 especies de briófitos recolectados en 19 hayedos de Navarra (España). Se establecen comparaciones entre las taxocenosis muscinales propias de cada tipo de hayedo reconocido (Saxifrago hirsutae-Fagetum Br.-BI. 1967, Helleboro-Fagetum O. de Bolos (1948) 1957, Scillo-Fagetum Br.-BI. 1952 em. O. de Bolos 1957 e Isopyro-Fagetum Montserrat 1968). Los porcentajes de elementos corológicos y afinidades ecológicas de la flora muscinal en cada sintaxon difieren entre sí y respecto al conjunto de la brioflora de los hayedos; estas diferencias están en relación con la sinecología de los "Fagetum". Summary: Bryophytic composition of the Fagus sylvatica L. woods in Navarra (Spain). A check-list of 175 species of bryophytes collected over 19 woods of Fagus sylvatica L. in Navarra (Spain) is presented. Comparations between the moss flora of every kind of wood (Saxifrago hirsutae-Fagetum Br.-BI. 1967, Helleboro-Fagetum O. de Bolos (1948) 1957, Scillo-Fagetum Br.-BI. 1952 em. O. de Bolos 1957 and Isopyro-Fagetum Montserrat 1968) are made. The chorologie and ecology composition of the moss flora of every sintaxa is different; differences are related with the sinecology of "Fagetum"

Editorial: Building Mathematical Models for Multicriteria and Multiobjective Applications

In our daily lives or professional settings, there are many decision problems involving multiple criteria, which may be conflicting and incommensurable. The complexity of real-world decision and the plethora of factors involved necessitate the implementation of sound theoretical frameworks for structuring decision-making processes. Multicriteria Decision Making/Aid (MCDM/A) and multiobjective methods can be highly useful for decision makers (DMs) in such tasks. Multicriteria and multiobjective approaches provide a wide variety of methodological tools for supporting the DMs when facing real-world decision problems when designing and analyzing mathematical models, representing both the preferences of decision makers and the various characteristics of the decision problems at hand in a number of areas

Phenomenology of Supersymmetric Theories with and without R-Parity

We review supersymmetry models with and without R-parity. After briefly describing the Minimal Supersymetric Standard Model and its particle content we move to models where R-parity is broken, either spontaneously or explicitly. In this last case we consider the situation where R-parity is broken via bilinear terms in the superpotential. The radiative breaking of these models is described in the context of $b$--$\tau$ and $b$--$\tau$--$t$ unification. Finally we review the phenomenology of these R-parity violating models.Comment: 9 pages, 5 Figures in Postscript. Talk given at the EuroConference on Frontiers in Particle Astrophysics and Cosmology, San Feliu de Guixols, Spain, 30 September - 5 October, 200

Shot noise in a diffusive F-N-F spin valve

Fluctuations of electric current in a spin valve consisting of a diffusive conductor connected to ferromagnetic leads and operated in the giant magnetoresistance regime are studied. It is shown that a new source of fluctuations due to spin-flip scattering enhances strongly shot noise up to a point where the Fano factor approaches the full Poissonian value.Comment: 5 pages, 3 figure

Development of Neutron Probes for Characterization of Hazardous Materials in the Sub-surface Medium

Neutron probes are being developed at the Idaho National Engineering and Environmental Laboratory (INEEL) for the detection, identification and quantification of hazardous materials in the ground. Such materials include plutonium, uranium, americium, chlorine and fluorine. Both a Neutron Gamma (NG) probe and a Prompt Fission Neutron (PFN) probe are being developed. The NG probe is used primarily for nuclide identification and quantification measurements. The PFN is used mostly for the detection and measurement of fissile material, but also for the determination of thermal neutron macroscopic absorption cross sections of the various elements comprising the ground matrix. Calibration of these probes will be carried out at the INEEL using an indoor facility that has been designed for this activity

Obstacles, levers and impacts of organic farming development in Camargue

We are presenting an analysis of the obstacles and levers for the development of organic cropping systems in Camargue, documented with a multicriteria analysis of scenarios of organic farming (OF) development. This communication is built using results from on-farm agronomic monitoring, stakeholders and farmers’ interviews and the use of models for integrated assessment of scenarios. At the farm level, the obstacles are related to identification of profitable cropping systems and rotations that include enough rice, conversion being therefore risky as impacting financial management and requiring a labour reorganisation. At the regional level, the constraints are related to the absence of advisory services for technical issues, and to the lack of coordination among the different stakeholders, to the low incentive of the public policies to convert, and to a relatively opaque organization of the supply chains. At the regional level, we analysed the consequences of two scenarios related to OF development on criteria such as the rice surface area, the quantity and quality of water, energy consumption or the employment generated. These results are expected to contribute to the definition of an action plan about OF development by the local stakeholders

Configuration Complexities of Hydrogenic Atoms

The Fisher-Shannon and Cramer-Rao information measures, and the LMC-like or shape complexity (i.e., the disequilibrium times the Shannon entropic power) of hydrogenic stationary states are investigated in both position and momentum spaces. First, it is shown that not only the Fisher information and the variance (then, the Cramer-Rao measure) but also the disequilibrium associated to the quantum-mechanical probability density can be explicitly expressed in terms of the three quantum numbers (n, l, m) of the corresponding state. Second, the three composite measures mentioned above are analytically, numerically and physically discussed for both ground and excited states. It is observed, in particular, that these configuration complexities do not depend on the nuclear charge Z. Moreover, the Fisher-Shannon measure is shown to quadratically depend on the principal quantum number n. Finally, sharp upper bounds to the Fisher-Shannon measure and the shape complexity of a general hydrogenic orbital are given in terms of the quantum numbers.Comment: 22 pages, 7 figures, accepted i

Simulation of redistributive and erosive effects in a-Si under Ar+ irradiation

Abstract Ion beams are frequently used in industry for composition control of semiconducting materials as well as for surface processing and thin films deposition. Under certain conditions, low- and medium energy ions at high fluences can produce nanoripples and quantum dots on the irradiated surfaces. In the present work, we focus our attention on the study of irradiation of amorphous silicon (a-Si) target with 250 eV and 1 keV Ar+ ions under different angles, taking into special consideration angles close to the grazing incidence. We use the molecular dynamics (MD) method to investigate how much the cumulative displacement of atoms due to the simulated ion bombardment contribute to the patterning effect. The MD results are subsequently analysed using a numerical module Pycraters that allows the prediction of the rippling effect. Ripple wavelengths estimated with Pycraters are then compared with the experimental observations, as well as with the results obtained by using the binary collisions approximation (BCA) method. The wavelength estimation based on the MD results demonstrates a better agreement with the experimental values. In the framework of the utilized analytical model, it can be mainly attributed to the fact that the BCA ignores low energy atomic interactions, which, however, provide an important contribution to the displacement of atoms following an ion impact.Peer reviewe