UV-B absorbing compounds in present-day and fossil pollen, spores, cuticles, seed coats and wood: evaluation of a proxy for solar UV radiation

Rozema, J.,Blokker, P.,Fuertes, M.A.Mayoral,Broekman, R. Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.9

UV-B absorbing compounds (UACs) in present-day and fossil pollen, spores, cuticles, seed coats and wood have been evaluated as a proxy for past UV. This proxy may not only provide information on variation of stratospheric ozone and solar UV in the period preceding and during the Antarctic ozone hole (1974-present day), but also on the development and variation of the stratospheric ozone layer and solar surface UV during the evolution of life on Earth. Sporopollenin and cutin are highly resistant biopolymers, preserving well in the geological record and contain the phenolic acids p-coumaric (pCA) and ferulic acid (FA). pCA and FA represent a good perspective for a plant-based proxy for past surface UV radiation since they are induced by solar UV-B via the phenylpropanoid pathway (PPP). UV-B absorption by these monomers in the wall of pollen and spores and in cuticles may prevent damage to the cellular metabolism. Increased pCAand FA in pollen of Vicia faba exposed to enhanced UV-B was found in greenhouse experiments. Further correlative evidence comes from UV-absorbing compounds in spores from 1960.2000 comparing exposure of land plants (Lycopodium species) to solar UV before and during ozone depletion and comparing plants from Antarctica (severe ozone depletion), Arctic, and other latitudes with less or negligible ozone depletion. Wood-derived compounds guaiacyl (G), syringyl (S), and p-hydroxyphenyl (P) are produced via the PPP. The proportions of P, G, and S in the lignin differ between various plant groups (e.g. dicotyledons/monocotyledons, gymnosperms/angiosperms). It is hypothesized that this lignin composition and derived physiological and physical properties of lignin (such as tree-ring wood density) has potential as a proxy for palaeo-UV climate. However validation by exposure of trees to enhanced UV is lacking. pCAand FA also form part of cutin polymers and are found in extant and fossil Ginkgo leaf cuticles as shown by thermally-assisted hydrolysis and methylation (THM)-pyrolysis-GC-MS. Potentially, the time scale for reconstruction of ozone column thickness and UV-B based on the UAC UV proxy may be decadal, centennial, millennial and possibly billenial. For further development of the UACs and pCA and FA-based UV proxy, it is necessary to obtain the UV dose.response (content of UACs, pCA and FA in sporopollenin and cutin) relationships for validation, based on outdoor UV radiation manipulations experiments with plants, and comparative analysis of stored plants (herbaria) or fossil material of the same or related plant species.

Sulfur-containing activated carbons with greatly reduced content of bottle neck pores for double-layer capacitors: a case study for pseudocapacitance detection

Gu, Wentian,Sevilla, Marta,Magasinski, Alexandre,Fuertes, Antonio B.,Yushin, Gleb The Royal Society of Chemistry 2013 Energy & environmental science Vol.6 No.8

<P>Synthesis of S-doped activated carbons (ACs) by carbonization and simultaneous activation of S-based polymers was found to be an efficient route to produce porous carbons for double layer capacitors (EDLCs) with high specific energy and power densities combined with low self-discharge. Here we investigate for the first time the processing-structure–property relationships related to the formation of polythiophene-derived ACs for EDLC applications. Sulfide bridges present in the polymer precursor were found to depress the shrinkage of the smallest micropores during the carbonization process and allow for the enhanced ion transport within the produced AC electrodes. The cyclic voltammetry (CV) measurements on S-doped ACs produced at 800 and 850 °C showed high specific capacitance (up to ∼200 F g<SUP>−1</SUP>) and no significant self-discharge in neutral aqueous electrolytes. More importantly, these capacitance values remained virtually identical for a sweep rate increasing from 1 to 50 mV s<SUP>−1</SUP>. The observed capacitance retention is quite remarkable for thick electrodes of ∼200 μm and a large AC particle size of 10–100 μm. It indicates great potential of the proposed synthesis technology for EDLCs operating at high frequencies and high currents. In the course of our systematic studies of AC performance in different electrolytes we found a strong correlation between the large pseudocapacitance and the significant self-discharge in ACs. We harness the difference between the characteristic times required to establish a double layer and that of the pseudocapacitive redox reactions and propose a simple method to estimate the fraction of pseudocapacitance. The proposed method is particularly valuable in cases when CV measurements do not show clear characteristic reduction–oxidation peaks.</P> <P>Graphic Abstract</P><P>Synthesis of S-doped activated carbons (ACs) by carbonization and activation of S-based polymers was found to be an efficient route to produce porous carbons for double layer capacitors with high specific energy and power densities. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3ee41182f'> </P>

Reliable Multicast with B.I.E.R.

Yoann Desmouceaux,Thomas Heide Clausen,Juan Antonio Cordero Fuertes,W. Mark Townsley 한국통신학회 2018 Journal of communications and networks Vol.20 No.2

Inter-network multicast protocols, which build and maintainmulticast trees, incur both explicit protocol signalling, andmaintenance of state in intermediate routers in the network. Bitindexedexplicit replication (B.I.E.R.) is a technique which can providea multicast service yet removes such complexities: intermediaterouters are unencumbered by group management, and no pergroupstate is to be maintained. This paper explores the use of B.I.E.R. as a basis for developingan efficient and reliable multicast mechanism, where redundanttraffic is avoided, essential traffic is forwarded along shortestpaths, and no per-flow state is required in intermediate routers. Evaluated by way of both an analytical model and network simulationboth in generic and in real network topologies with varyingbackground traffic loads, the proposed B.I.E.R.-based reliablemulticast mechanism exhibits attractive performance attributes: Itattains delivery success rates as high as any other reliable multicastservice, but with significantly better link utilisation and no per-flowor per-group state in intermediate routers of the network.

길리엄 카레라 건축

길리엄 카레라 건축(Guillem Carrera Arquitecte),아드리아 굴라(사진),Mauricio Fuertes(사진),카사스 에코텍(사진),크리스티나 세라(사진),호세 헤비아(사진) 현대건축사 2020 월간 CONCEPT Vol.- No.252

Characterization of the New n_TOF Neutron Beam: Fluence, Profile and Resolution

C. Guerrero,V. Becares,D. Cano-Ott,M. Fernandez-Ordonez,E. Gonzalez-Romero,F. Martin-Fuertes,T. Martinez,E. Mendoza,G. Pina,J. Quinones,V. Vlachoudis,M. Calviani,S. Andriamonje,M. Brugger,F. Cerutti,E 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

After a halt of four years, the n_TOF spallation neutron facility at CERN has resumed operation in November 2008 with a new spallation target characterized by an improved safety and engineering design, resulting in a more robust overall performance and efficient cooling. The first measurement during the 2009 run has aimed at the full characterization of the neutron beam. Several detectors, such as calibrated fission chambers, the n\textunderscore TOF Silicon Monitor, a MicroMegas detector with ^(10)B and ^(235)U samples, as well as liquid and solid scintillators have been used in order to characterize the properties of the neutron fluence. The spatial profile of the beam has been studied with a specially designed "X-Y" MicroMegas which provided a 2D image of the beam as a function of neutron energy. Both properties have been compared with simulations performed with the FLUKA code. The characterization of the resolution function is based on results from simulations which have been verified by the study of narrow capture resonances of ^(56)Fe, which were measured as part of a new campaign of (n, γ) measurements on Fe and Ni isotopes.