Aportación al estudio sobre la fenología reproductora de las algas pardas y verdes del litoral del Sureste de España

We provide information about the reproductive phenology of 30 taxa of brown algae and 20 of green ones in the South-East of Spain, comparing the phenologic behaviour observed with the one already described in adjoining areas of the Spanish Mediterranean. We also interpreted the reproductive phenology according to the observations made on the coast and the consulted bibliography.En este trabajo se aporta información sobre la fenología reproductura de 30 tiixones de algas pardas y 20 de algas verdes en el Sureste de España, comparando el comportamiento fenolágico observado con el descrito en áreas adyacentes del mediterráneo español. Paralelamente, se interpreta la fenología detectada en base a las observaciones realizadas en el litoral y a la bibliografía consultada

The role of the electrolyte on the SERS spectra of pyridine

SERS spectra of pyridine has been recorded on a silver electrode in a potential range from 0.0 to -1.20 V with a saline solution, pyridine / KCl (0.1M / 0.1M), by using the 514.5 nm exciting line by us [1]. Under these experimental conditions, the maximum intensity of the enhanced 8a and 9a bands is reached at -0.75 V and -1.20 V, respectively, being the 9a band what dominates the spectrum at negative electrode potential. Although this behavior has been explained under a resonant charge transfer mechanism, the nature of the electronic resonance processes involved in the enhancement of each band is different. The 8a band is enhanced due to an electronic excitation between the ground and excited charge transfer electronic state of the metal-adsorbate surface complex, while the activity of the 9a band is due to a plasmon-like excitation taking into account an overall electronic structure of small metal clusters [2] which is able to selectively modify the relative intensities of specific SERS band. We intend now to record pyridine SERS spectra under the same experimental conditions but varying only the type of electrolyte in order to check how it affects the relative intensities and vibrational wavenumbers of the bands as well as the electrode potential to which the enhanced bands reach the maximum intensity. Different electrolytes like KCl, NaCl, KBr, NaBr and Na2SO4, have been selected in such way that allows us to compare SERS spectra in which changes only the cation or the anion of the electrolyte. From the analysis of all these SERS spectra, it can be concluded that no significant wavenumbers shifts have been detected, while the relative intensities of the bands and the electrode potential to which the maximum intensity is reached are slightly modified. NaBr electrolyte requieres more negative electrode potential in order to enhance the 8a and 9a bands and to resolve the 12 and 1 pair. Acknowledgements We are grateful to the Spanish MINECO (CTQ2012-31846) and Junta de Andalucía (FQM-5156 and 6778), for financial support. References [1] J.F. Arenas, I. López Tocón, J.C. Otero, and J.I. Marcos, J. Phys. Chem. 100, 9254-9261 (1996). [2] J. Román-Pérez, I. López-Tocón, J.L. Castro, J. F. Arenas, J. Soto and J.C. Otero, Phys. Chem. Chem. Phys.17, 2326-2329 (2015).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Electrochemical SERS spectra of isonicotinic acid analyzed under a photoinduced charge-transfer mechanism

Isonicotinic (IN) acid is one of the three monocarboxilic derivatives of pyridine in which the acid group is located in para-position of the heterocyclic ring. It is a weak acid (pK2=4.86) and therefore, it is not completely ionized in neutral aqueous solutions, being the zwitterion and the anion the majority chemical species at neutral pH. In acidic solutions (pK1=1.84) the pyridinic nitrogen atom can be protonated yielding a third chemical species with positive charge [1]. In addition, IN acid shows two functional centres that can interact with the silver metallic surface such as the carboxilate group and the aromatic nitrogen atom. Therefore, the analysis of the SERS spectra of IN has been focused on identifying the chemical species adsorbed on the silver surface and its centre of interaction by considering the participation of a photoinduced charge-transfer (CT) mechanism in each particular SERS record as we have previously detected in the SERS of pyridine derivatives [2]. SERS spectra of the IN acid (5x10-3 M) have been recorded on silver at electrode potentials ranging from 0.00 up to -1.00 V and at different pH by using 0.1 M Na2SO4 aqueous solution as electrolyte. The figure shows the SERS recorded at basic pH. The experimental set up is described elsewhere and the excitation line of 514.5 nm wavelength was used. [2]. The detection of the presence of CT processes, which are similar to resonance Raman, requires to carry out quantum mechanical calculations [2].Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Notas corológicas del macrofitobentos de Andalucía (España)

Ampliamos el catálogo para las costas andaluzas en 32 especies, de las cuales, 7 son nuevas citas para la Peninsula Ibérica: Audouinella endozoica (Darb.) Dixon, Fosliella minutula (Fosl.) Ganesan, Lomentaria compressa (Kütz.) Kylin, Polysiphonia cladorrhiza Ar-diss., P. ruchingeri C. Ag., P. stuposa Zanard. y Pseudocrouania ischiana Funk y otras 4 lo son para el Mediterráneo español: Audouinella thuretii (Born.) Wölkerling, Feldmannia simplex (Crouan frat.) Hamel, Phaeophila wittrockii (Wille) Nielsen y Ralfsia bornetii Kuckut.The catalogue of benthic algae in Andalusia (Spain) coasts is extendet, to include 32 news species, 7 are news records to Iberian Peninsula and 4 to Mediterranean coasts of Spain

Aportaciones al conocimiento ficogeográfico del sureste de la Península Ibérica

Se hace un ensayo biogeográfico sobre la flora algal bentónica del Sureste de la Península Ibérica constatándose, la existencia de un componente de tropicalidad más acusado que en las áreas próximas, y al mismo tiempo, se comprueba la existencia de correlación entre el cociente R/F y el porcentaje de especies tropicales y subtropicales a lo largo del Mediterráneo hispano.A biogeographic research on the seaweeds of the South East Iberian Peninsula is made, verifying the existence of a tropicality element which is greater in the surroundings, and, at the same time, the existence of a correlation between the R/P quotient and the percentage of tropical and subtropical species along the Spanish Mediterranean Sea is verified too

Sobre la presencia de algunas especies de algas tropicales en el litoral del sureste ibérico

We make the commentary of four tropical species found at different states in SE of Spain, scarcely quoted in the Mediterranean Sea. This species are: Dipterosiphonia dendritica (Ag.) Schmitz in Engl. et Prantl, Liagora farinosa Lamouroux, Polystrata fosliei (Weber van Bosse) Denizot and Pocockiella variegata (Lamouroux) Papenfuss.Se comenta la presencia de las especies Dipterosiphonia dendritica (Ag.) Schmitz in Engl. et Prantl, Liagora farinosa Lamouroux, Polystrata fosliei (Weber van Bosse) Denizot y Pocockiella variegata (Lamourux) Papenfuss halladas en varias localidades del SE de la Peninsula Ibérica comentando su ecologia, corología y ciertos rasgos morfoestructurale

Fundamentals and Applications of Surface-Enhanced Raman Spectroscopy (SERS)

When a molecule is adsorbed on some metallic nanostructured surfaces such as silver, copper or gold, it can undergo an enormous enhancement of the Raman signal giving rise to the so called Surface-Enhanced Raman Scattering (SERS). The high sensitivity of this effect allows an accurate structural study of adsorbates at very low concentrations. The SERS effect has historically been associated with the substrate roughness on two characteristic length scales. Surface roughness on the 10 to 100 nm length scale supports localized plasmon resonances which are considered as the dominant enhancement mechanism of SERS (Electromagnetic Enhancement Mechanism: SERS-EM). It is usually accepted that these electromagnetic resonances can increase the scattered intensity by an average factor of ca. 104 to 107. A secondary mechanism often thought to require atomic scale roughness is referred to as Charge Transfer (CT) Enhancement Mechanism (SERS-CT). This mechanism involves the photoinduced transfer of an electron from the metal to the adsorbate or vice versa and involves new electronic excited CT states which result from adsorbate–substrate chemical interactions. It is also estimated that such SERS-CT mechanism can enhance the scattering cross-section by a factor of ca. 10 to 102. These two mechanisms can operate simultaneously, depending on the particular systems and experimental conditions, making difficult to recognize each one and to estimate their relative magnitude in a particular spectrum.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

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

SERS study of different species of p-aminothiophenol adsorbed on silver nanoparticles

In the present work we have focused the discussion on the experimental and theoretical SERS spectra of the organic compound pATP recorded on silver colloids. The huge SERS of pATP on metal substrates is significantly different from its ordinary Raman spectra due to the formation of a new specie namely p,p’ –dimercaptoazobenzene (DMAB). The features of the SERS spectra of pATP are strongly dependent on many factors as i.e. the laser power density or the laser wavelength but there are still important aspects to understand as, for example, the effect of the concentration that has already been studied before by our group. In this case we have analyzed the effect of the concentration at different wavelengths on the SERS spectra of pATP on silver nanoparticles.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Sobre la fenología reproductora de las algas rojas en el litoral de sudeste de España (Alborán Oriental)

Se describe la fenología reproductora observada en 86 táxones de algas rojas del Sureste de España. Paralelamente, y en base al análisis efectuado durante seis anos (19831988) de 2.543 poblaciones pertenecientes a 23 familias, se cuantifican las frecuencias relativas en ellas de las fases esporofítica, gametofítica y carposporofítica, constatándose la dominancia de la frecuencia de poblaciones estériles seguida por las esporofíticas. Las frecuencias de poblaciones carposporofíticas y gametofíticas son netamente inferiores y a veces despreciables. Finalmente, se barajan posibles causas para explicar las frecuencias observadas.This paper describes the reproduction observed on 86 taxa of red algae from south east Spain. Likewise, the relative frecuencies of their sporophytic, gametophytic and 171 carposporophytic phases are quantified on the basis of analyses of 2.543 algae formations belonging to 23 families carried out over a six year period (1983-88). Sterile formations 73 prove dominant, sporophytic formations being the second most frequent. Carposporophytic 261 and gametophytic formations are a good deal less frequent, sometimes negligible. Last, various reasons for the observed frequencies are contemplated and examined