3,569 research outputs found
La Cueva de la Pileta : conferencia dada en la Sociedad Malagueña de Ciencias, el dia 26 de marzo de 1943
No full textDatos tomados de la cub.Nuevos descubrimientos en la Cueva de la Pileta / por Jose Perez de Barradas y Manuel Maura y Salas.La Venus de Benaojan / [Simeon Gimenez Reyna][Museo de la Alcazaba de Malaga / Juan Temboury Alvarez]Aportacion al conocimiento de la cinegetica prehistorica / Simeon Gimenez Reyna.La Cueva de la Pileta / Simeon Gimenez Reyna.Las cuevas neoliticas costeras de Granada y Malaga / Jose Perez de Barradas.Copia digital : Diputación de Málaga. Biblioteca Cánovas del Castillo, 201
Geopolymer Designed with Pumice Stone from Ecuador
No full text[EN] The present investigation focuses on the
creation of a geopolymer, using pumice stone from Ecuador
as a precursor material. The chemical composition of the
pumice and the alkaline activation of the geopolymer with
NaOH and Na2SiO3 were validated through a multi-criteria
analysis that was used to identify the best mine among the
ones located in Cotopaxi, Chimborazo, and Tungurahua
states. Through laboratory tests, it was obtained that the
best pumice stone had the presence of aluminum oxide and
silicon in its composition, as well as amorphous particles,
with a size of 40 to 50µm. The percentage of aluminum that
was found in the mines of Cotopaxi, Imbabura, and
Tungurahua states was 0.60%, 0.68%, and 1.50%
respectively. In the fineness modulus tests, it stands out that
more than 80% passes the 75µm sieve. In regards to the
activation of the geopolymer, the average resistance of the
deposits was Cotopaxi 22.60 MPa, Imbabura 23.03 MPa,
and Tungurahua 23.03 MPa. In the geopolymer concrete,
the average resistance values of each of the deposits were:
Cotopaxi 4.21 MPa, Imbabura 8.05 MPa, and Tungurahua
8.67 MPa. The multicriteria analysis showed that the best
option to create geopolymer concrete comes from the mine
located in Tungurahua. It should be noted that the increase
in NaOH concentration, maintaining the ratio of 2.4 in
geopolymer cubes between Na2SiO3/NaOH as an activating
solution, induces an increase in compressive strength. The
concrete made from the Tungurahua mine, made up of 50%
geopolymer and 50% aggregates. It is the one that showed
the best properties with a compressive strength of 16.16
MPa, cured in an oven for 24 hours and at a temperature of
80°C. The design of geopolymer concrete that replaces the
use of portland cement is the first step to reduce the
pollution produced by hydraulic cement.Andrade, A.; Castillo, T.; Paredes, M.; Gimenez-Carbo, E.; García, V. (2022). Geopolymer Designed with Pumice Stone from Ecuador. Civil Engineering and Architecture. 10(5):1864-1880. https://doi.org/10.13189/cea.2022.100513S1864188010
Changes in the sugars and volatile compounds profiles associated with anthocyanin accumulation in oranges: Blood vs. blond varieties, and slightly pigmented vs. intensely pigmented blood fruit
No full text[EN] Blood oranges accumulate anthocyanins in their peel and pulp, which give them their characteristic red colour. To investigate whether there is a specific volatile compounds profile for blood oranges, we compared the volatile composition of the blood varieties `Moro¿, `Tarocco Rosso¿ and `Sanguinelli¿ to that of the blond ones `Cadenera¿, `Salustina¿ and `Hamlim¿ using a non-targeted approach based on HS¿SPME¿GC¿MS. Moreover, fruits from each blood orange variety were divided into slightly and intensely pigmented fruits, and individual sugars and anthocyanins were determined by liquid chromatography to investigate whether their profiles depend on the degree of pulp pigmentation. A total of 101 volatile compounds were identified in this study. Hierarchical Cluster Analysis, including all compounds, revealed that blood oranges have no unique volatiles profile that makes them more similar to one another than to the blond varieties. For blood orange varieties, our results corroborated that greater anthocyanin accumulation in the most intensely pigmented fruit is associated with higher sugar content (an increase of 0.8¿2.3 % depending on the variety). Moreover, we reported for the first time that anthocyanin accumulation is also associated with changes in the volatiles profile. A Multifactor Analysis including data on volatiles, sugars and anthocyanin showed that sucrose is the sugar more strongly linked to anthocyanin accumulation. A group of volatile compounds, mainly esters (ethyl acetate, ethyl-2-methyl butanoate and ethyl-2-butenoate) along with ethanol, are present at increased levels, sometimes even doubling in the most intensely pigmented samples compared to the slightly pigmented ones. These results open the door to further investigate the possible metabolic link between sugars and anthocyanins accumulation and changes in volatile compounds.This work was supported by the project IVIA-GVA 52401E from the Instituto Valenciano de Investigaciones Agrarias. This project was also co-financed by the European Union through the ERDF Program 2021 2027 Comunitat Valenciana. Author Adrian Gimenez-Sanchis wish to thank the Regional Ministry of Innovation, Universities, Science,and Digital Society (Generalitat Valenciana) for the financial support of their contract (FDEGENT/2020/004).Giménez-Sanchis, A.;Bermejo-Del Castillo, A.;Besada Ferreiro, CM. (2024). Changes in the sugars and volatile compounds profiles associated with anthocyanin accumulation in oranges: Blood vs. blond varieties, and slightly pigmented vs. intensely pigmented blood fruit. Food Research International. 197(Part A). https://doi.org/10.1016/j.foodres.2024.115199S197Part
Determination of |V(ub)| / |V(cb)| with DELPHI at LEP
No full textThe ratio of the CKM quark-mixing matrix elements \V-ub\/\V-cb\ has been measured using B hadron semileptonic decays. The analysis uses the reconstructed mass M-X of the secondary hadronic system produced in association with an identified lepton. Since B → X(u)l (v) over bar transitions are characterised by hadronic masses below those of the D mesons produced in B → X(c)l (v) over bar transitions, events with a reconstructed value of M-X significantly below the D mass are selected. Further signal enrichments are obtained using the topology of reconstructed decays and hadron identification. A fit to the numbers of decays in the b → u enriched and depleted samples with M-X above and below 1.6 GeV/c(2) and to the shapes of the lepton energy distribution in the B rest frame gives \V-ub\/\V-cb\ = 0.103 (+0.011)(-0.012) (stat.) +/- 0.016(syst.) +/- 0.010(model) and, correspondingly, a charmless semileptonic B decay branching fraction of BR(B → X(u)l (v) over bar)= (1.57 +/- 0.35 (stat.) +/- 0.48(syst.) +/- 0.27(model)) x 10(-3)
Cellulose nanocrystal-derived carbon electrodes for sustainable potassium-ion charge storage systems
No full textWe have here produced carbon electrode materials derived from Crystalline NanoCellulose (CNC) for low-cost potassium-ion based energy storage systems through conventional annealing as well as through a fast and energy efficient microwave assisted carbonization process. A two-step 4-minute synthesis with ZnCl2 activation in a domestic microwave leads to a micro/mesoporous carbon with high surface area (SBET~1800 m2 g 1). These CNC-derived carbons, if assessed in symmetric supercapacitor C/C cells cycled with 0.5 M K2SO4 aqueous electrolyte, show reversible capacitance values up to 66 F g 1 at current densities of 5 A g 1, retaining 83% of its initial capacitance after 10.000 cycles without any conducting additive. Due to its large electrochemical window of 1.7 V, a competitive energy density for an aqueous system of 20.9 W h kg 1 is achieved. A hybrid aqueous capacitor built with this carbon as negative electrode and coupled with a Prussian White as positive results in cell capacitance values up to 135 F g 1 under a voltage operation window of 1.8 V in 0.5 M K2SO4. On the other hand, non-activated carbons produced through a 2.25 hour thermal annealing at 900 ◦C, present much lower surface area (SBET~450 m2 g 1), most of it due to its high micropore volume. This low external and mesoporous surface area carbon is a competitive anode material for potassium-ion batteries with a reversible capacity of ~200 mA h g 1 cycled at 28 mA g 1 using 3.9 M KFSI in DME electrolyte (favourably most of it below 1 V vs K+/K) in a potassium half-cell with >80% retention in 100 cycles. The present research shows that sustainable CNC derived carbons produced through energy efficient methods are competitive electrode materials in low-cost K based energy storge systems.Depto. de Química InorgánicaFac. de Ciencias QuímicasTRUEpu
Experimental and computational study of conductivity of multilayer graphene in polypropylene nanocomposites
No full text[EN] We study the electric conductivity of compounds formed by multilayer graphene in polypropylene. Our study makes a comparative analysis between the experimental and computational results. To obtain an experimental measurement of the electronic properties, we deposited multilayer graphene (MLG) nanoparticles over a polypropylene matrix. The deposition was made over several stages, in which we added to the polymer matrix different percentages of MLG nanoparticles using the melt compounding technique, and we studied the conductivities of the nanocomposites by means of electrochemical impedance spectroscopy (EIS). The second part consists of computational calculations, in which we studied the electronic properties of a graphene sheet under a polypropylene molecule with different slabs in the monomer. In both analyses, there is a strong percolation phenomenon with a percolation threshold of around 18% of the MLG nanoparticles. Before the percolation threshold, the charge carriers are constrained in the polypropylene molecule, making the system an insulating material and creating p-type doping. After the percolation threshold, the charge carriers are constrained in the graphene, making the system a conductor material and creating n-type doping with conductivity values of around 20 S m(-1). This phenomenon is a consequence of a change in the mechanism of charge transfer in the interface between the polypropylene molecule and graphene sheet. To describe the charge transfer mechanism, it is necessary to consider the quantum effect. The incorporation of the quantum effects and the percolation phenomenon make it possible for the theoretical conductivity to be close to the conductivity measured experimentally.This research has been supported by the ENE/2015-69203-R project, granted by the Ministerio de Economia y Competitividad (MINECO), Spain. Also, the authors are grateful to UNAM-DGAPA-PAPIIT projects IG 100618 y IG 114818, DGTIC-UNAM for access to the Miztli-UNAM supercomputer LANCAD-UNAM-DGTIC-055, and UNAM-DGAPA for the Postdoctoral grant for Roxana M. del Castillo.Del Castillo, RM.; Del Castillo, LF.; Calles, AG.; Compañ Moreno, V. (2018). Experimental and computational study of conductivity of multilayer graphene in polypropylene nanocomposites. Journal of Materials Chemistry C. 6:7232-7241. https://doi.org/10.1039/c8tc01135dS723272416H. G. Karian , Handbook of polypropylene and polypropylene composites , RheTec, Inc. , Whitmore Lake, Michigan , 2nd edn, 2003 , https://books.google.es/books?hl=es&lr=&id=C0nzeNPUpoIC&oi=fnd&pg=PP1&dq=Handbook+of+polypropylene+and+polypropylene+composites&ots=LYqYBYg45n&sig=3gtYXigr8_O8CUJeefBCtGI7QXA#v=onepage&q=Handbook%20of%20polypropylene%20and%20polypropylene%20composites&f=falseRath, T., & Li, Y. (2011). Nanocomposites based on polystyrene-b-poly(ethylene-r-butylene)-b-polystyrene and exfoliated graphite nanoplates: Effect of nanoplatelet loading on morphology and mechanical properties. Composites Part A: Applied Science and Manufacturing, 42(12), 1995-2002. doi:10.1016/j.compositesa.2011.09.002Kim, M.-S., Yan, J., Kang, K.-M., Joo, K.-H., Kang, Y.-J., & Ahn, S.-H. (2013). Soundproofing ability and mechanical properties of polypropylene/exfoliated graphite nanoplatelet/carbon nanotube (PP/xGnP/CNT) composite. International Journal of Precision Engineering and Manufacturing, 14(6), 1087-1092. doi:10.1007/s12541-013-0146-3Zhang, K., Yu, H.-O., Shi, Y.-D., Chen, Y.-F., Zeng, J.-B., Guo, J., … Wang, M. (2017). Morphological regulation improved electrical conductivity and electromagnetic interference shielding in poly(l-lactide)/poly(ε-caprolactone)/carbon nanotube nanocomposites via constructing stereocomplex crystallites. Journal of Materials Chemistry C, 5(11), 2807-2817. doi:10.1039/c7tc00389gMohd Radzuan, N. A., Yusuf Zakaria, M., Sulong, A. B., & Sahari, J. (2017). The effect of milled carbon fibre filler on electrical conductivity in highly conductive polymer composites. Composites Part B: Engineering, 110, 153-160. doi:10.1016/j.compositesb.2016.11.021Li, Q., Yao, F.-Z., Liu, Y., Zhang, G., Wang, H., & Wang, Q. (2018). High-Temperature Dielectric Materials for Electrical Energy Storage. Annual Review of Materials Research, 48(1), 219-243. doi:10.1146/annurev-matsci-070317-124435Qiao, Y., Yin, X., Zhu, T., Li, H., & Tang, C. (2018). Dielectric polymers with novel chemistry, compositions and architectures. Progress in Polymer Science, 80, 153-162. doi:10.1016/j.progpolymsci.2018.01.003Rosehr, A., & Luinstra, G. A. (2017). Polypropylene composites with finely dispersed multi-walled carbon nanotubes covered with an aluminum oxide shell. Polymer, 120, 164-175. doi:10.1016/j.polymer.2017.05.045Bolotin, K. I., Sikes, K. J., Jiang, Z., Klima, M., Fudenberg, G., Hone, J., … Stormer, H. L. (2008). Ultrahigh electron mobility in suspended graphene. Solid State Communications, 146(9-10), 351-355. doi:10.1016/j.ssc.2008.02.024Banszerus, L., Schmitz, M., Engels, S., Goldsche, M., Watanabe, K., Taniguchi, T., … Stampfer, C. (2016). Ballistic Transport Exceeding 28 μm in CVD Grown Graphene. Nano Letters, 16(2), 1387-1391. doi:10.1021/acs.nanolett.5b04840Terrés, B., Chizhova, L. A., Libisch, F., Peiro, J., Jörger, D., Engels, S., … Stampfer, C. (2016). Size quantization of Dirac fermions in graphene constrictions. Nature Communications, 7(1). doi:10.1038/ncomms11528Zhang, H.-B., Zheng, W.-G., Yan, Q., Yang, Y., Wang, J.-W., Lu, Z.-H., … Yu, Z.-Z. (2010). Electrically conductive polyethylene terephthalate/graphene nanocomposites prepared by melt compounding. Polymer, 51(5), 1191-1196. doi:10.1016/j.polymer.2010.01.027Chung, D. D. L. (2015). A review of exfoliated graphite. Journal of Materials Science, 51(1), 554-568. doi:10.1007/s10853-015-9284-6T. Bayerl , A.Benedito , A.Gallegos , G. B.Mitschang and B.Galindo , Melting of Polymer-Polymer Composites by Particulate Heating Promoters and Electromagnetic Radiation , in Synthetic Polymer-Polymer Composites , ed. D. Bhattacharyya and S. Fakirov , Carl HanserVerlag GmbH & Co. KG , 2012 , ch. 24, pp. 39–64 10.3139/9781569905258.002Harper, J., Price, D., & Zhang, J. (2005). Use of Fillers to Enable the Microwave Processing of Polyethylene. Journal of Microwave Power and Electromagnetic Energy, 40(4), 219-227. doi:10.1080/08327823.2005.11688543Galindo, B., Benedito, A., Gimenez, E., & Compañ, V. (2016). Comparative study between the microwave heating efficiency of carbon nanotubes versus multilayer graphene in polypropylene nanocomposites. Composites Part B: Engineering, 98, 330-338. doi:10.1016/j.compositesb.2016.04.082Asadi, K., Kronemeijer, A. J., Cramer, T., Jan Anton Koster, L., Blom, P. W. M., & de Leeuw, D. M. (2013). Polaron hopping mediated by nuclear tunnelling in semiconducting polymers at high carrier density. Nature Communications, 4(1). doi:10.1038/ncomms2708Fan, Z., Gong, F., Nguyen, S. T., & Duong, H. M. (2015). Advanced multifunctional graphene aerogel – Poly (methyl methacrylate) composites: Experiments and modeling. Carbon, 81, 396-404. doi:10.1016/j.carbon.2014.09.072Zabihi, Z., & Araghi, H. (2016). Monte Carlo simulations of effective electrical conductivity of graphene/poly(methyl methacrylate) nanocomposite: Landauer-Buttiker approach. Synthetic Metals, 217, 87-93. doi:10.1016/j.synthmet.2016.03.024Xia, X., Zhong, Z., & Weng, G. J. (2017). Maxwell–Wagner–Sillars mechanism in the frequency dependence of electrical conductivity and dielectric permittivity of graphene-polymer nanocomposites. Mechanics of Materials, 109, 42-50. doi:10.1016/j.mechmat.2017.03.014F. M. Bickelhaupt and E. J.Baerends , Kohn–Sham Density Functional Theory: Predicting and Understanding Chemistry . in Reviews in Computational Chemistry , 2007 , ed. K. B. Lipkowitz and B. Boyd Donald , John Wiley & Sons, Inc. , vol. 15, pp. 1–89 10.1002/9780470125922.ch1/summaryPerdew, J. P., Burke, K., & Ernzerhof, M. (1996). Generalized Gradient Approximation Made Simple. Physical Review Letters, 77(18), 3865-3868. doi:10.1103/physrevlett.77.3865Methfessel, M., & Paxton, A. T. (1989). High-precision sampling for Brillouin-zone integration in metals. Physical Review B, 40(6), 3616-3621. doi:10.1103/physrevb.40.3616Monkhorst, H. J., & Pack, J. D. (1976). Special points for Brillouin-zone integrations. Physical Review B, 13(12), 5188-5192. doi:10.1103/physrevb.13.5188Files: C.pbe-van_ak.UPF, H.pbe-van_ak.UPF, N.pbe-van_ak.UPF, and O.pbe-van_ak.UPF, http://www.quantum-espresso.orgVanderbilt, D. (1990). Soft self-consistent pseudopotentials in a generalized eigenvalue formalism. Physical Review B, 41(11), 7892-7895. doi:10.1103/physrevb.41.7892Sørensen, T. S., & Compañ, V. (1995). Complex permittivity of a conducting, dielectric layer containing arbitrary binary Nernst–Planck electrolytes with applications to polymer films and cellulose acetate membranes. J. Chem. Soc., Faraday Trans., 91(23), 4235-4250. doi:10.1039/ft9959104235Drüschler, M., Huber, B., & Roling, B. (2011). On Capacitive Processes at the Interface between 1-Ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate and Au(111). The Journal of Physical Chemistry C, 115(14), 6802-6808. doi:10.1021/jp200395jSerghei, A., Tress, M., Sangoro, J. R., & Kremer, F. (2009). Electrode polarization and charge transport at solid interfaces. Physical Review B, 80(18). doi:10.1103/physrevb.80.184301F. Kremer and A.Schoenhals , Broadban Dielectric Spectroscopy , Springer , Berlin , 2003Coelho, R. (1983). Sur la relaxation d’une charge d’espace. Revue de Physique Appliquée, 18(3), 137-146. doi:10.1051/rphysap:01983001803013700Macdonald, J. R. (1953). Theory of ac Space-Charge Polarization Effects in Photoconductors, Semiconductors, and Electrolytes. Physical Review, 92(1), 4-17. doi:10.1103/physrev.92.4Klein, R. J., Zhang, S., Dou, S., Jones, B. H., Colby, R. H., & Runt, J. (2006). Modeling electrode polarization in dielectric spectroscopy: Ion mobility and mobile ion concentration of single-ion polymer electrolytes. The Journal of Chemical Physics, 124(14), 144903. doi:10.1063/1.2186638Greenhoe, B. M., Hassan, M. K., Wiggins, J. S., & Mauritz, K. A. (2016). Universal power law behavior of the AC conductivity versus frequency of agglomerate morphologies in conductive carbon nanotube-reinforced epoxy networks. Journal of Polymer Science Part B: Polymer Physics, 54(19), 1918-1923. doi:10.1002/polb.24121Novoselov, K. S. (2004). Electric Field Effect in Atomically Thin Carbon Films. Science, 306(5696), 666-669. doi:10.1126/science.1102896Del Castillo, R. M., & Sansores, L. E. (2015). Study of the electronic structure of Ag, Au, Pt and Pd clusters adsorption on graphene and their effect on conductivity. The European Physical Journal B, 88(10). doi:10.1140/epjb/e2015-60001-2Galpaya, D., Wang, M., Liu, M., Motta, N., Waclawik, E., & Yan, C. (2012). Recent Advances in Fabrication and Characterization of Graphene-Polymer Nanocomposites. Graphene, 01(02), 30-49. doi:10.4236/graphene.2012.12005I. Zvyagin . Charge Transport via Delocalized States in Disordered Materials . in Charge Transport in Disordered Solids with Applications in Electronics , ed. S. Baranovsky , John Wiley & Sons, Inc. , 2006 , pp. 1–48 10.1002/0470095067.ch1/summaryLeenaerts, O., Partoens, B., & Peeters, F. M. (2009). Adsorption of small molecules on graphene. Microelectronics Journal, 40(4-5), 860-862. doi:10.1016/j.mejo.2008.11.022Hashemi, R., & Weng, G. J. (2016). A theoretical treatment of graphene nanocomposites with percolation threshold, tunneling-assisted conductivity and microcapacitor effect in AC and DC electrical settings. Carbon, 96, 474-490. doi:10.1016/j.carbon.2015.09.103Xia, X., Wang, Y., Zhong, Z., & Weng, G. J. (2017). A frequency-dependent theory of electrical conductivity and dielectric permittivity for graphene-polymer nanocomposites. Carbon, 111, 221-230. doi:10.1016/j.carbon.2016.09.078The determination of the elastic field of an ellipsoidal inclusion, and related problems. (1957). Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 241(1226), 376-396. doi:10.1098/rspa.1957.0133Trotta, S., Marmo, F., & Rosati, L. (2017). Evaluation of the Eshelby tensor for polygonal inclusions. Composites Part B: Engineering, 115, 170-181. doi:10.1016/j.compositesb.2016.10.018L. D. Landau , E. M.Lifshitz and L. P.Pitaevskii , Electrodynamics of Continuous Media , Pergamon Press , New York , 3rd edn, 1984Wang, Y., Weng, G. J., Meguid, S. A., & Hamouda, A. M. (2014). A continuum model with a percolation threshold and tunneling-assisted interfacial conductivity for carbon nanotube-based nanocomposites. Journal of Applied Physics, 115(19), 193706. doi:10.1063/1.4878195Wang, Y., Shan, J. W., & Weng, G. J. (2015). Percolation threshold and electrical conductivity of graphene-based nanocomposites with filler agglomeration and interfacial tunneling. Journal of Applied Physics, 118(6), 065101. doi:10.1063/1.4928293Wehling, T. O., Yuan, S., Lichtenstein, A. I., Geim, A. K., & Katsnelson, M. I. (2010). Resonant Scattering by Realistic Impurities in Graphene. Physical Review Letters, 105(5). doi:10.1103/physrevlett.105.056802Stauber, T., Peres, N. M. R., & Guinea, F. (2007). Electronic transport in graphene: A semiclassical approach including midgap states. Physical Review B, 76(20). doi:10.1103/physrevb.76.205423R. M. Del Castillo and L. E.Sansores . Adsorption of Metal Clusters on Graphene and Their Effect on the Electrical Conductivity , in Graphene Materials – Advanced Applications , ed. G. Z. Kyzas and A. C. Mitropoulos , INTECH , 2017 , https://www.intechopen.com/books/graphene-materials-advanced-applications/adsorption-of-metal-clusters-on-graphene-and-their-effect-on-the-electrical-conductivit
Measurement of V(cb) from the decay process anti-B0 ---> D*+ lepton- anti-neutrino
No full textA new precise measurement of \V-cb\ and of the branching ratio BR([(Bover bar](0)→ D(+*)l(-)[([nu])over bar](l)) has been performed using a sample of about 5000 semileptonic decays (B) over bar (0) → D(*+)l(-)[([nu])over bar](l), selected by the DELPHI detector at LEP 1 by tagging the soft pion from D*+ → D(0)pi (+). The results are: V-cb = (39.0 +/- 1.5 (stat.)(- 2.6)(+2.5) (syst. exp.) +/- 1.3(ayst. th.)) x 10(-3). BR((B) over bar0 → D(*+)l(-)[([nu])over bar](l)) = (4.70 +/- 0.13(stat.)(-0.31)(+0.36) (syst. exp.))%. The analytic dependencies of the differential cross-section and of the Isgur-Wise form factor as functions of the variable w = v(B)0 . v(D)* have also been obtained by unfolding the experimental resolution
Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery
No full textIn the version of this article initially published, the ATLAS Collaboration
author names, affiliations and acknowledgements were omitted and
have now been included in the HTML and PDF versions of the article
An Organopalladium-pvc Membrane For Sulphur Dioxide Optical Sensing
No full textThe development of a sensing membrane for the determination of gaseous sulphur dioxide is described. An organopalladium complex, Pd2(dpm) 2Cl2 (dichloro-bis-(diphenylphosphine)-methane dipalladium I), was immobilised in a poly(vinyl chloride) thin film plasticised with ortho-nitrophenyloctylether (o-NPOE). Several membranes were prepared, using 20, 25 and 30% of PVC; 1, 5 and 8% of palladium complex and enough o-NPOE to make a total of 100 mg, which was dissolved in 1.0 mL of THF. The sensing membranes were obtained by manual deposition of 10, 15 and 20 μL of the solution onto cellulose acetate films, which were left to dry for 24 h and then stored in a desiccator sheltered from ambient light. The membrane was placed in an acrylic flow cell, in which the common end of a bifurcated optical fibre bundle was adapted and placed 1 mm from the membrane. Reflectance measurements were performed from 400 to 800 nm, after exposing the membrane to 0 to 500 ppm v of SO2 in air, at a flow rate of 500 mL min -1. The membrane composed of 20% PVC, 72% o-NPOE and 8% palladium complex showed the best performance and the film prepared from 20 μl of solution provided the highest signal (ca 160 mV upon exposure to 500 ppm v SO2). Measurements made at 530 nm showed a linear response range up to 300 ppmv, with a detection limit of 3.5 ppm v. By employing a flow rate of 500 mL min-1, response times (t90%) of 3 and 2 min were obtained for reaction of the membrane with SO2 and for reverse response upon exposure to dry nitrogen, respectively. Although the palladium complex also reacts with carbon monoxide in solution, this interference was not observed for concentrations up to 1000 ppmv of CO. The membrane showed a lifetime of ca. 2 months when stored in a desiccator. © 2004 Elsevier B.V. All rights reserved.1071 SPEC. ISS.4752http://www.epa.gov/air/airtrends/sulfur2.html, accessed on 11/march/2004Kuratli, M., Pretsch, E., Sulfur dioxide-selective optodes (1994) Anal. Chem., 66, pp. 85-91Carballo, R., Dall'Orto, V.C., Lo Balbo, A., Rezzano, I., Determination of sulfide by flow injection analysis using a poly [Ni-(protoporphyrin IX)] chemically modified electrode (2003) Sens. Actuators B, 88, pp. 155-161Chiou, C.Y., Chou, T.C., Amperometric SO2 gas sensor based on solid polymer electrolytes (2002) Sens. Actuators B, 87, pp. 1-7Li, H., Wang, Q.J., Xu, J.M., Zhang, W., Jin, L.T., A novel nano-Au- assembled amperometric SO2 gas sensor: Preparation, characterization and sensing behavior (2002) Sens. Actuators B, 87, pp. 18-24Hodgson, A.W.E., Jacquinot, P., Hauser, P.C., Electrochemical sensor for the detection of SO2 in low-ppb range (1999) Anal. Chem., 71, pp. 2831-2837Matsuguchi, M., Tamai, K., Sakai, Y., SO2 gas sensors using polymers with different amino groups (2001) Sens. Actuators B, 77, pp. 363-367Guimarães, M.O., Detection of sulfur dioxide using piezoelectric quartz crystal microbalance (1997) Anal. Lett., 30, pp. 2159-2174Mohr, G.J., Draxler, S., Trznadel, K., Lehmann, F., Lippitsch, M.E., Synthesis and characterization of fluorophore-absorber pairs for sensing of ammonia based on fluorescence (1998) Anal. Chim. Acta, 360, pp. 119-128Raimundo Jr., I.M., Narayanaswamy, R., Simultaneous determination of relative humidity and ammonia in air employing an optical fibre sensor and artificial neural network (2001) Sens. Actuators B, 74, pp. 60-68Choi, M.M., Xiao, D., Oxygen-sensitive reverse-phase optode membrane using silica gel-absorbed ruthenium (II) complex embedded in gelatin film (1999) Anal. Chim. Acta, 387, pp. 197-205Miller, B., Hauser, P.C., Fluorescence optical sensor for low concentrations of dissolved carbon dioxide (1996) Analyst, 121, pp. 339-343Freeman, M.K., Bachas, L.G., Fiber optic sensor for NOx (1992) Anal. Chim. Acta, 256, pp. 269-275Nezel, T., Fakler, A., Zhylyak, G., Mohr, G.J., Spichiger-Keller, U.E., A highly sensitive NO2-selective optode membrane (2000) Sens. Actuators B, 70, pp. 165-169Stangelmayer, A., Klimant, I., Wolfbeis, O.S., Optical sensors for dissolved sulfur dioxide (1998) Fresenius J. Anal. Chem., 362, pp. 73-76De Marcos, S., Alcubierre, N., Galbán, J., Castillo, J.R., Reagentless system for sulphite based on polyaniline (2004) Anal. Chim. Acta, 502, pp. 7-13Razek, T.M.A., Miller, M.J., Hassan, S.S.M., Arnold, M.A., Optical sensor for sulfur dioxide based on fluorescence quenching (1999) Talanta, 50, pp. 491-498Lin, J.M., Qu, F., Yamada, M., Chemiluminescent investigation of tris(2,2′-bipyridyl)ruthenium(II) immobilized on a cationic ion-exchange resin and its application to analysis (2002) Anal. Bioanal. Chem., 374, pp. 1159-1164Papkovsky, D., Uskova, M.A., Ponomarev, G.V., Korpela, T., Kulmala, S., Guilbault, G.G., Optical sensing of sulfite with a phosphorescent probe (1998) Anal. Chim. Acta, 374, pp. 1-9Gimenez, I.F., Alves, O.L., Immobilisation of complexes containing metal-metal bonds in porous Vycor glass and subsequent insertion of gas molecules into the Pd-Pd bonds (2002) Glass Technol., pp. 166-169Benner, L.S., Olmstead, M.M., Hope, H., Balch, A.L., Reversible insertion of sulfur dioxide into palladium-palladium bonds. the preparation and structure of Pd2(μ-SO2) (Ph 2PCH2PPh2)2Cl2 (1978) J. Organomet. Chem., 153, pp. 31-35Benner, L.S., Balch, A.L., Novel reactions of metal-metal bonds. Insertion of isocyanides and carbon monoxide into the palladium-palladium bond of some Pd (I) dimmers (1978) J. Am. Chem. Soc., 13, pp. 6099-6106Balch, A.L., Benner, L.S., Olmstead, M.M., Novel reactions of metal-metal bonds. Adittion of sulfur dioxide and sulfur to Pd2(μ-SO2) (Ph2PCH 2PPh2)2Cl2 and the oxidation of coordinated sulfide (1979) Inorg. Chem., 18, pp. 2996-3003Brook, T.E., Narayanaswamy, R., Polymeric films in optical gas sensor (1998) Sens. Actuators B, 51, pp. 77-83Wang, E., Meyerhoff, M.E., Anion selective optical sensing with metalloporphyrin-doped polymeric films (1993) Anal. Chim. Acta, 283, pp. 673-68
Determination of vertical bar V-ub vertical bar/vertical bar V-cb vertical bar with DELPHI at LEP
No full textDELPHI Collaboration: et al.The ratio of the CKM quark-mixing matrix elements |Vub|/|Vcb| has been measured using B hadron semileptonic decays. The analysis uses the reconstructed mass MX of the secondary hadronic system produced in association with an identified lepton. Since BªX lln transitions are characterised by hadronic masses below those of the D mesons produced in BªX lln transitions, events with a reconstructed value of MX significantly below the D mass are selected. Further signal enrichments are obtained using the topology of reconstructed decays and hadron identification. A fit to the numbers of decays in the b→u enriched and depleted samples with MX above and below 1.6 GeV/c2 and to the shapes of the lepton energy distribution in the B rest frame gives V rV s0.103 stat."0.016 syst."0.010 model and, correspondingly, a charmless semileptonic B decay branching fraction of BR(BRBªX llns1.57"0.35 stat."0.48 syst." u .. y3 0.27model =10.We acknowledge in particular the support of Austrian Federal Ministry of Science and Traffics, GZ 616.364/2-III/2a/98, FNRS–FWO, Belgium, FINEP, CNPq, CAPES, FUJB and FAPERJ, Brazil, Czech Ministry of Industry and Trade, GA CR 202/96/0450 and GA AVCR A1010521, Danish Natural Research Council, Commission of the European Communities (DG XII), Direction des Sciences de la Matire, CEA, France, Bundesministerium fur Bildung, Wissenschaft, Forschung und Technologie, Germany, General Secretariat for Research and Technology, Greece, National Science Foundation (NWO) and Foundation for Research on Matter (FOM), The Netherlands, Norwegian Research Council, State Committee for Scientific Research, Poland, 2P03B06015, 2P03B1116 and SPUB/P03/178/98, JNICT–Junta Nacional de Investigação Cientı́fica e Tecnologica, Portugal, Vedecka grantova agentura MS SR, Slovakia, Nr. 95/5195/134, Ministry of Science and Technology of the Republic of Slovenia, CICYT, Spain, AEN96–1661 and AEN96-1681, The Swedish Natural Science Research Council, Particle Physics and Astronomy Research Council, UK, Department of Energy, USA, DE–FG02–94ER40817.Peer reviewe
- …
