Evaluación preliminar de emisiones de plomo en automóviles

El presente trabajo reporta emisiones de plomo contenido en el material particulado emitido por el escape. de una muestra típica de automóviles a gasolina, mediame muestreo isocinético a volumen constante según normas de la Environmental Protection Agency de USA. Los resultados obtenidos muestran ww emisión promedio de 7.4 ± 0.68 (mg Pb · km- 1) obtenido al aplicar un ciclo de conducción representativo de la A 1·enida Bemardo O'Higgins en el área de restricción vehicular. simulado en dinamómetro de rodillos y a través de dilución variable de gases de escape. Este valor sugiere que la información utilizada en la evaluación de los inventarios de emisiones en Santiago, sobredimensiona la contribución del material particulado proveniente de vehículos livianos a gasolina

Comparación de efectos de un aditivo comercial y un encendido por descarga continua sobre las emisiones primarias de un motor de automóvil

El presente trabajo muestra un estudio comparativo de las emisiones de S02 , NOx, HCHO, CO y HC producidas por un motor Datsun 1 .5 L acoplado a un dinanómetro hidráulico. En un caso, se usó un sistema de encendido por "descarga continua" y en el otro, se usó un aditivo comercial "For Gas" marca Wynn' s. En las condiciones analizadas, el aditivo comercial mostró una mayor eficiencia en la reducción de contaminames, que el encendido electrónico. En particular, las emisiones de S02 se redujeron hasta un 20% comparativas al sistema convencional

New features in the ionic states of N2O4: Experimental and theoretical study

We present a combined experimental and theoretical study focused on the ionic states of the N2O4 molecule. Experimental results regarding photoionization induced by the synchrotron radiation SOLEIL in the 13.5-15.5 eV energy range were obtained using the electron-ion velocity vector correlation method. The potential energy curves for the dissociation of the N-N bond were computed within ab initio multireference wave functions based methods (CASSCF and CASPT2) for the first electronic states of N2O 4 and N2O4

Detailed damage mechanisms assessment in composite materials by means of X-ray tomography

This research focused on the evaluation of damage formation on ±45º carbon fiber laminates subjected to tensile tests. The damage was evaluated by means of X-ray tomography. A high density of cracks developed during the plateau of the stress-strain curve and were qualitatively analyzed, showing that the inner plies eventually developed a higher crack concentration than the outer plies. Delamination started to occur in the outermost ply interface when the slope after the plateau of the stress-strain curve began to increase

VISIR: experiences and challenges

It is of crucial importance the integration of practical sessions in engineering curricula owing to their significant role in understanding engineering concepts and scientific phenomena. However, the lack of practical sessions due to the high costs of the equipment and the unavailability of instructors has caused a significant declination in experimentation in engineering education. Remote laboratories have tackled this issues providing online reusable and shared workbenches unconstrained by neither geographical nor time considerations. Thereby, they have extremely proliferated among universities and integrated into engineering curricula over the last decade. This contribution compiles diverse experiences based on the deployment of the remote laboratory, Virtual Instrument Systems in Reality (VISIR), on the practices of undergraduate engineering grades at various universities within the VISIR community. It aims to show the impact of its usage on engineering education concerning the assessments of students and teachers as well. In addition, the paper address the next challenges and future works carried out at several universities within the VISIR community

The little-studied cluster Berkeley 90 I. LS III +46 11: a very massive O3.5 If* + O3.5 If* binary

Context. It appears that most (if not all) massive stars are born in multiple systems. At the same time, the most massive binaries are hard to find owing to their low numbers throughout the Galaxy and the implied large distances and extinctions. Aims. We want to study LS III +46 11, identified in this paper as a very massive binary; another nearby massive system, LS III +46 12; and the surrounding stellar cluster, Berkeley 90. Methods. Most of the data used in this paper are multi-epoch high S/N optical spectra, although we also use Lucky Imaging and archival photometry. The spectra are reduced with dedicated pipelines and processed with our own software, such as a spectroscopic-orbit code, CHORIZOS, and MGB. Results. LS III +46 11 is identified as a new very early O-type spectroscopic binary [O3.5 If* + O3.5 If*] and LS III +46 12 as another early O-type system [O4.5 V((f))]. We measure a 97.2-day period for LS III +46 11 and derive minimum masses of 38.80 ± 0.83 M⊙ and 35.60 ± 0.77 M⊙ for its two stars. We measure the extinction to both stars, estimate the distance, search for optical companions, and study the surrounding cluster. In doing so, a variable extinction is found as well as discrepant results for the distance. We discuss possible explanations and suggest that LS III +46 12 may be a hidden binary system where the companion is currently undetected.J.M.A. and A.S. acknowledge support from [a] the Spanish Government Ministerio de Economía y Competitividad (MINECO) through grants AYA2010-15 081, AYA2010-17 631, and AYA2013-40 611-P and [b] the Consejería de Educación of the Junta de Andalucía through grant P08-TIC-4075. J.M.A. was also supported by the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy and he is grateful to the Department of Physics and Astronomy at Texas A&M University for their hospitality during some of the time this work was carried out. I.N., A.M., J.A., and J.L. acknowledge support from [a] the Spanish Government Ministerio de Economía y Competitividad (MINECO) through grant AYA2012-39 364-C02-01/02, [b] the European Union, and [c] the Generalitat Valenciana through grant ACOMP/2014/129. R.H.B. acknowledges support from FONDECYT Project 1 140 076. S.S.-D. acknowledges funding by [a] the Spanish Government Ministerio de Economía y Competitividad (MINECO) through grants AYA2010-21 697-C05-04, AYA2012-39 364-C02-01, and Severo Ochoa SEV-2011-0187 and [b] the Canary Islands Government under grant PID2 010 119. J.S.-B. acknowledges support by the JAE-PreDoc program of the Spanish Consejo Superior de Investigaciones Científicas (CSIC). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555

Catalytic asymmetric synthesis of diazabicyclo[3.1.0]hexanes by 1,3-dipolar cycloaddition of azomethine ylides with azirines

Substituted 1,3-diazabicyclo[3.1.0]hexanes with two contiguous quaternary stereocentres are readily prepared by catalytic asymmetric [3+2] cycloaddition of α-substituted iminoesters with azirines. High diastereoselectivities and enantioselectivities (up to 98% ee) are achieved using CuI/(R)-Fesulphos as the catalytic systemWe thank the Spanish Ministerio de Economía, Industria y Competitividad (Grant CTQ2015-66954-P, MINECO/FEDER, UE) and FEDER/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación (Grant PGC2018-098660-B-I00) for financial suppor

Searches for neutrino counterparts of gravitational waves from the LIGO/Virgo third observing run with KM3NeT

The KM3NeT neutrino telescope is currently being deployed at two different sites in the Mediterranean Sea. First searches for astrophysical neutrinos have been performed using data taken with the partial detector configuration already in operation. The paper presents the results of two independent searches for neutrinos from compact binary mergers detected during the third observing run of the LIGO and Virgo gravitational wave interferometers. The first search looks for a global increase in the detector counting rates that could be associated with inverse beta decay events generated by MeV-scale electron anti-neutrinos. The second one focuses on upgoing track-like events mainly induced by muon (anti-)neutrinos in the GeV–TeV energy range. Both searches yield no significant excess for the sources in the gravitational wave catalogs. For each source, upper limits on the neutrino flux and on the total energy emitted in neutrinos in the respective energy ranges have been set. Stacking analyses of binary black hole mergers and neutron star-black hole mergers have also been performed to constrain the characteristic neutrino emission from these categories.Grants PID2021-124591NB-C41, -C42, -C43 funded by MCIN/AEI/10.13039/501100011033 and, as appropriate, by “ERDF A way of making Europe”, by the “European Union” or by the “European Union NextGenerationEU/PRTR”Programa de Planes Complementarios I+D+I (refs. ASFAE/2022/023, ASFAE/2022/014)Programa Prometeo (PROMETEO/2020/019) and GenT (refs. CIDEGENT/2018/034, /2019/043, /2020/049. /2021/23) of the Generalitat ValencianaJunta de Andalucía (ref. SOMM17/6104/UGR, P18-FR-5057)MSC program (ref. 101025085)Programa María Zambrano (Spanish Ministry of Universities, funded by the European Union, NextGenerationEU)The European Union’s Horizon 2020 Research and Innovation Programme (ChETEC-INFRA — Project no. 101008324)Francqui foundatio

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO