117 research outputs found
Comportamento eletroquímico e determinação eletroanalítica da sulfadiazina
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-graduação em Química, Florianópolis, 2009Sulfadiazina foi quantificada em duas amostras de produtos farmacêuticos usando voltametria de onda quadrada. O sinal analítico foi obtido por redução em vez de oxidação da sulfa sobre eletrodo de carbono vítreo. A determinação eletroanalítica foi realizada em solução-tampão Britton-Robinson 0,04 mol L-1 com pH 6,8. A redução irreversível da sulfadiazina foi observada em -1,49 V vs. Ag/AgCl. A curva analítica foi obtida na faixa de concentração entre 62,7 e 340 µmol L-1 (R = 0,9986) e o limite de detecção foi 10,9 µmol L-1. Para uma amostra analisada, os valores de recuperação ficaram entre 94,9 e 101,1%, enquanto para a outra amostra foram entre 96,0 e 104,6%, indicando que a composição da matriz não interfere nos resultados analíticos. A exatidão da metodologia eletroanalítica foi comparada com o método padrão titulação amperométrica
Characterization of UV-enhanced SiPMs for imaging in a high pressure xenon electroluminescent TPC
No full textLow-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield
No full text[EN] High pressure xenon Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification are being proposed for rare event detection such as directional dark matter, double electron capture and double beta decay detection. The discrimination of the rare event through the topological signature of primary ionisation trails is a major asset for this type of TPC when compared to single liquid or double-phase TPCs, limited mainly by the high electron diffusion in pure xenon. Helium admixtures with xenon can be an attractive solution to reduce the electron diffu- sion significantly, improving the discrimination efficiency of these optical TPCs. We have measured the electroluminescence (EL) yield of Xe-He mixtures, in the range of 0 to 30% He and demonstrated the small impact on the EL yield of the addition of helium to pure xenon. For a typical reduced electric field of 2.5 kV/cm/bar in the EL region, the EL yield is lowered by similar to 2%, 3%, 6% and 10% for 10%, 15%, 20% and 30% of helium concentration, respectively. This decrease is less than what has been obtained from the most recent simulation framework in the literature. The impact of the addition of helium on EL statistical fluctuations is negligible, within the experimental uncertainties. The present results are an important benchmark for the simulation tools to be applied to future optical TPCs based on Xe-He mixtures.The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the European Union's Framework Programme for Research and Innovation Horizon 2020 (2014-2020) under the Marie Sklodowska-Curie Grant Agreements No. 674896, 690575 and 740055; the Ministerio de Economa y Competitividad of Spain under grants FIS2014-53371-C04, RTI2018-095979, the Severo Ochoa Program SEV-2014-0398 and the Mara de Maetzu Program MDM-2016-0692; the GVA of Spain under grants PROMETEO/2016/120 and SEJI/2017/011; the Portuguese FCT under project PTDC/FIS-NUC/2525/2014, under project UID/FIS/04559/2013 to fund the activities of LIBPhys, and under grants PD/BD/105921/2014, SFRH/BPD/109180/2015; the U.S. Department of Energy under contracts number DEAC02-06CH11357 (Argonne National Laboratory), DE-AC0207CH11359 (Fermi National Accelerator Laboratory), DE-FG02-13ER42020 (Texas A& M) and DE-SC0019223/DESC0019054 (University of Texas at Arlington); and the University of Texas at Arlington. DGD acknowledges Ramon y Cajal program (Spain) under contract number RYC-2015-18820. We also warmly acknowledge the Laboratori Nazionali del Gran Sasso (LNGS) and the Dark Side collaboration for their help with TPB coating of various parts of the NEXT-White TPC. Finally, we are grateful to the Laboratorio Subterraneo de Canfranc for hosting and supporting the NEXT experiment.Fernandes, A.; Henriques, C.; Mano, R.; González-Díaz, D.; Azevedo, C.; Silva, P.; Gómez-Cadenas, J.... (2020). Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield. Journal of High Energy Physics (Online). (4):1-18. https://doi.org/10.1007/JHEP04(2020)034S1184D.R. Nygren, Columnar recombination: a tool for nuclear recoil directional sensitivity in a xenon-based direct detection WIMP search, J. Phys. Conf. Ser.460 (2013) 012006 [INSPIRE].G. Mohlabeng et al., Dark matter directionality revisited with a high pressure xenon gas detector, JHEP07 (2015) 092 [arXiv:1503.03937] [INSPIRE].N.S. Phan, R.J. Lauer, E.R. Lee, D. Loomba, J.A.J. Matthews and E.H. Miller, GEM-based TPC with CCD Imaging for Directional Dark Matter Detection, Astropart. Phys.84 (2016) 82 [arXiv:1510.02170] [INSPIRE].J. Martin-Albo et al., Sensitivity of NEXT-100 to neutrinoless double beta decay, JHEP05 (2016) 159 [arXiv:1511.09246] [INSPIRE].K. Nakamura et al., AXEL — a high pressure xenon gas TPC for neutrinoless double beta decay search, Nucl. Instrum. Meth.A 845 (2017) 394 [INSPIRE].D. Yu. Akimov, A.A. Burenkov, V.F. Kuzichev, V.L. Morgunov and V.N. Solovev, Low background experiments with high pressure gas scintillation proportional detector, physics/9704021 [INSPIRE].Yu. M. Gavrilyuk et al., A technique for searching for the 2K capture in124Xe with a copper proportional counter, Phys. Atom. Nucl.78 (2015) 1563 [INSPIRE].Yu. M. Gavrilyuk et al., Results of In-Depth Analysis of Data Obtained in the Experimental Search for 2K (2ν)-Capture in78Kr, Phys. Part. Nucl.49 (2018) 540 [INSPIRE].C.A.N. Conde and A.J.P.L. Policarpo, A Gas Proportional Scintillation Counter, Nucl. Instrum. Meth.53 (1967) 7.A.J.P.L. Policarpo, M.A.F. Alves and C.A.N. Conde, The Argon-Nitrogen Proportional Scintillation Counter, Nucl. Instrum. Meth.55 (1967) 105.J.M.F. dos Santos et al., Development of portable gas proportional scintillation counters for x-ray spectrometry, X-Ray Spectrom.30 (2001) 373.NEXT collaboration, Accurate γ and MeV-electron track reconstruction with an ultra-low diffusion Xenon/TMA TPC at 10 atm, Nucl. Instrum. Meth.A 804 (2015) 8 [arXiv:1504.03678] [INSPIRE].NEXT collaboration, Characterisation of NEXT-DEMO using xenon KαX-rays, 2014 JINST9 P10007 [arXiv:1407.3966] [INSPIRE].NEXT collaboration, Energy calibration of the NEXT-White detector with 1% resolution near Qββof136Xe, JHEP10 (2019) 230 [arXiv:1905.13110] [INSPIRE].R. Lüscher et al., Search for beta beta decay in Xe-136: New results from the Gotthard experiment, Phys. Lett.B 434 (1998) 407 [INSPIRE].NEXT collaboration, First proof of topological signature in the high pressure xenon gas TPC with electroluminescence amplification for the NEXT experiment, JHEP01 (2016) 104 [arXiv:1507.05902] [INSPIRE].NEXT collaboration, Background rejection in NEXT using deep neural networks, 2017 JINST12 T01004 [arXiv:1609.06202] [INSPIRE].NEXT collaboration, The Next White (NEW) Detector, 2018 JINST13 P12010 [arXiv:1804.02409] [INSPIRE].H. Qiao et al., Signal-background discrimination with convolutional neural networks in the PandaX-III experiment using MC simulation, Sci. China Phys. Mech. Astron.61 (2018) 101007 [arXiv:1802.03489] [INSPIRE].NEXT collaboration, Secondary scintillation yield of xenon with sub-percent levels of CO2additive for rare-event detection, Phys. Lett.B 773 (2017) 663 [arXiv:1704.01623] [INSPIRE].C.M.B. Monteiro et al., Secondary Scintillation Yield in Pure Xenon, 2007 JINST2 P05001 [physics/0702142] [INSPIRE].C.M.B. Monteiro, J.A.M. Lopes, J.F. C.A. Veloso and J.M.F. dos Santos, Secondary scintillation yield in pure argon, Phys. Lett.B 668 (2008) 167 [INSPIRE].C.A.B. Oliveira et al., A simulation toolkit for electroluminescence assessment in rare event experiments, Phys. Lett.B 703 (2011) 217 [arXiv:1103.6237] [INSPIRE].E.D.C. Freitas et al., Secondary scintillation yield in high-pressure xenon gas for neutrinoless double beta decay (0νββ) search, Phys. Lett.B 684 (2010) 205 [INSPIRE].C.M.B. Monteiro et al., Secondary scintillation yield from gaseous micropattern electron multipliers in direct dark matter detection, Phys. Lett.B 677 (2009) 133 [INSPIRE].C.M.B. Monteiro, L.M.P. Fernandes, J.F. C.A. Veloso, C.A.B. Oliveira and J.M.F. dos Santos, Secondary scintillation yield from GEM and THGEM gaseous electron multipliers for direct dark matter search, Phys. Lett.B 714 (2012) 18 [INSPIRE].C. Balan et al., MicrOMEGAs operation in high pressure xenon: Charge and scintillation readout, 2011 JINST6 P02006 [arXiv:1009.2960] [INSPIRE].C.M.B. Monteiro, L.M.P. Fernandes, J.F. C.A. Veloso and J.M.F. dos Santos, Secondary scintillation readout from GEM and THGEM with a large area avalanche photodiode, 2012 JINST7 P06012 [INSPIRE].C.D.R. Azevedo et al., An homeopathic cure to pure Xenon large diffusion, 2016 JINST11 C02007 [arXiv:1511.07189] [INSPIRE].C.D.R. Azevedo et al., Microscopic simulation of xenon-based optical TPCs in the presence of molecular additives, Nucl. Intrum. Meth.A 877 (2018) 157 [arXiv:1705.09481] [INSPIRE].NEXT collaboration, Electroluminescence TPCs at the Thermal Diffusion Limit, JHEP01 (2019) 027 [arXiv:1806.05891] [INSPIRE].R.C. Lanza et al., Gas scintillators for imaging of low energy isotopes, IEEE Trans. Nucl. Sci.34 (1987) 406.R. Felkai et al., Helium-Xenon mixtures to improve the topological signature in high pressure gas xenon TPCs, Nucl. Intrum. Meth.A 905 (2018) 82 [arXiv:1710.05600] [INSPIRE].NEXT collaboration, Electron Drift and Longitudinal Diffusion in High Pressure Xenon-Helium Gas Mixtures, 2019 JINST14 P08009 [arXiv:1902.05544] [INSPIRE].J.A.M. Lopes et al., A xenon gas proportional scintillation counter with a UV-sensitive large-area avalanche photodiode, IEEE Trans. Nucl. Sci.48 (2001) 312.C.M.B. Monteiro et al., An argon gas proportional scintillation counter with UV avalanche photodiode scintillation readout, IEEE Trans. Nucl. Sci.48 (2001) 1081.Advanced Photonix, Inc., 1240 Avenida Acaso, Camarillo, CA 93012, U.S.A. .L.M.P. Fernandes et al., Characterization of large area avalanche photodiodes in X-ray and VUV-light detection, 2007 JINST2 P08005 [physics/0702130] [INSPIRE].L.M.P. Fernandes, E.D.C. Freitas, M. Ball, J.J. Gomez-Cadenas, C.M.B. Monteiro, N. Yahlali et al., Primary and secondary scintillation measurements in a xenon Gas Proportional Scintillation Counter, 2010 JINST5 P09006 [Erratum ibid.5 (2010) A12001] [arXiv:1009.2719] [INSPIRE].C.A.B. Oliveira, M. Sorel, J. Martin-Albo, J.J. Gomez-Cadenas, A.L. Ferreira and J.F. C.A. Veloso, Energy Resolution studies for NEXT, 2011 JINST6 P05007 [arXiv:1105.2954] [INSPIRE].D.F. Anderson et al., A large area, gas scintillation proportional counter, Nucl. Instrum. Meth.163 (1979) 125.T.Z. Kowalski et al., Fano factor implications from gas scintillation proportional counter measurements, Nucl. Instrum. Meth.A 279 (1989) 567.T. Doke, Basic properties of high pressure xenon gas as detector medium, in Proceedings of the XeSAT, Tokyo Japan (2005), pg. 92.S.J.C. do Carmo et al., Experimental Study of the ω-Values and Fano Factors of Gaseous Xenon and Ar-Xe Mixtures for X-Rays, IEEE Trans. Nucl. Sci.55 (2008) 2637.A. Buzulutskov, E. Shemyakina, A. Bondar, A. Dolgov, E. Frolov, V. Nosov et al., Revealing neutral bremsstrahlung in two-phase argon electroluminescence, Astropart. Phys.103 (2018) 29 [arXiv:1803.05329] [INSPIRE]
Digital processing of large-area avalanche photodiode signals for X-ray spectrometry applications
No full textComputation of nodal marginal prices in the presence of load and generation cost Uncertainties
No full textArticle number 52072192009 6th International Conference on the European Energy Market, EEM 2009, 27 May 2009 through 29 May 2009 - Code 78380Marginal prices have been recognized as the core approach to the economic evaluation of generation and transmission services in an electricity market environment. In this context, this paper presents the New Fuzzy Optimal Power Flow algorithm as a model to addresses the impact of load and generation cost uncertainties in nodal marginal prices. Since loads and generation costs are represented by fuzzy numbers, nodal marginal prices will no longer be represented by deterministic values, but rather by fuzzy membership functions reflecting the specified uncertainties. The paper also presents the algorithm used for the integration of the transmission losses effect on the results. Since the proposed algorithm uses multiparametric programming techniques, it contributes to characterize in a better way the system behavior. Finally, it includes results based on the IEEE 24 bus/38 branch test system to illustrate the proposed approach.The first author thanks Fundação para a Ciência e Tecnologia, FCT, that funded this research through the PhD grant n.º SFRHlBD/34314/2006
Secondary scintillation yield from GEM and THGEM gaseous electron multipliers for direct dark matter search
No full textAbstractThe search for alternatives to PMTs as photosensors in optical TPCs for rare event detection has significantly increased in the last few years. In particular, in view of the next generation large volume detectors, the use of photosensors with lower natural radioactivity, such as large area APDs or GM-APDs, with the additional possibility of sparse surface coverage, triggered the intense study of secondary scintillation production in micropattern electron multipliers, such as GEMs and THGEMs, as alternatives to the commonly used uniform electric field region between two parallel meshes. The much higher scintillation output obtained from the electron avalanches in such microstructures presents an advantage in those situations. The accurate knowledge of the amount of such scintillation is important for correct detector simulation and optimization. It will also serve as a benchmark for software tools developed and/or under development for the calculation of the amount of such scintillation.The secondary scintillation yield, or electroluminescence yield, in the electron avalanches of GEMs and THGEMs operating in gaseous xenon and argon has been determined for different gas pressures. At 1 bar, THGEMs deliver electroluminescence yields that are more than one order of magnitude higher when compared to those achieved in GEMs and two orders of magnitude when compared to those achieved in a uniform field gap. The THGEM electroluminescence yield presents a faster decrease with pressure when comparing to the GEM electroluminescence yield, reaching similar values to what is achieved in GEMs for xenon pressures of 2.5 bar, but still one order of magnitude higher than that produced in a uniform field gap. Another exception is the GEM operating in argon, which presents an electroluminescence yield similar to that produced in a uniform electric field gap, while the THGEM achieves yields that are more than one order of magnitude higher
Changes in intestinal microbiota, immune- and stress-related transcript levels in Senegalese sole (Solea senegalensis) fed plant ingredient diets intercropped with probiotics or immunostimulants
No full textSenegalese sole (Solea senegalensis) is a highly valued flatfish that grows well with diets containing plant ingredients but their effects on immune competence is still a matter of debate. The current study aimed to examine changes in innate immune parameters and gut microbiota in Senegalese sole fed with 35% or 72% of plant ingredients with or without probiotic or yeast supplementation. Overall, fish fed diets with 72% of plant ingredients showed lower transcript levels of key immune- and stress-related genes in distal intestine, rectum and head-kidney than the 35% diets. In particular, hsp90b mRNA levels in distal intestine were down-regulated by 70% and 60% with the use of high content of plant ingredients in the diet containing the multispecies probiotic and autolyzed yeast, respectively. Denaturing gradient gel electrophoresis showed lower similarity values for distal intestine than rectum. Also fish fed high content of plant ingredients displayed lower similarity values, pointing to a difference in the microbial populations between fish fed different plant ingredient contents on the diet. Our data revealed that inclusion of plant ingredients was associated with differences in gene expression and a more diverse microbiota profile but without a significant effect on growth performance. Moreover, probiotic supplementation resulted in up-regulation of hsp90b, gpx, cat and apoa1 transcript levels in distal intestine concomitantly with a growth rate reduction compared to non-supplemented fish. Statement of relevance: There is an increasing trend in the aquaculture industry to replace fishmeal for plant ingredients, as a means of promoting sustainability of the industry. This paper contributes significantly to our limited knowledge of how plant ingredients and supplements affect gut microbiota and immunocompetence. © 2016 ElsevierS. M. G. Batista is supported by FCT — SFRH/BD/76668/2011. This work was also supported by the PROBIOSOLEA Project with the financial support of Quadro de Referência Estratégico Nacional — QREN and Programa Operacional Regional do Norte — ON2 (Ref. no. 13551), supported by the European fund for regional development FEDER. We would like to thank to CIIMAR/ICBAS (UP) and FBA (University of Nordland) for the use of the facilities and equipment and for technical support
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