Unravelling mechanistic insights in the platinum-catalysed dihydroalkoxylation of allenes

The mechanism of the platinum-catalysed dihydroalkoxylation of allenes to give acetals has been studied experimentally and by computational methods. Our findings further explain divergent reactivity encountered for platinum- and gold-vinyl intermediates after the first nucleophilic attack onto the coordinated allene, as well as provide new details on the catalytic cycle with platinum, uncovering enol ethers as resting states of the catalytic cycle, a S(E)Ox process via Pt(V)-H as the final protodemetallation step after the second nucleophilic attack when neutral platinum complexes are used, and a fast acid promoted addition of methanol to enol ethers when cationic platinum complexes are employed

Probabilidad de uso de instrumentos publicos: el caso de la industria vitivinicola chilena

120 pLa Industria Vitivinícola es parte importante de la economía nacional, por esta razón es que se hace interesante estudiar sobre la industria y los distintos factores que la componen. En esta investigación se presenta un análisis econométrico sobre la probabilidad de que las empresas de la Industria Vitivinícola nacional hagan uso de instrumentos públicos en la gestión del riesgo, partiendo desde la base teórica que todos los individuos son agentes racionales que intentan maximizar su bienestar. Además, estos individuos son agentes adversos al riesgo, es decir, están dispuestos a pagar una cantidad determinada con el fin de eliminar el riesgo en distintas situaciones. Desde esta base, la investigación se hace interesante, de manera de descubrir cuáles son las variables más relevantes en la toma de esta decisión, y así estimar la probabilidad de que distintas empresas nacionales utilicen instrumentos públicos. Esta información, que es escasa en el mercado, es de gran utilidad principalmente para el Gobierno debido a que es esta entidad la que está a cargo de los instrumentos públicos y además debe velar por la competitividad en la industria. Para llevar a cabo la estimación se hizo uso del software SPSS 15.0 e Eviews 4, que permitieron regresionar los modelos propuestos: Modelo de Probabilidad Lineal, Modelos Logit y Probit. Una vez realizada la regresión,fue preciso corroborar los resultados, aplicando algunas pruebas específicas que permitieron determinar que los modelos pronostican correctamente un 80,36% de los datos, además, que las variables incluidas son estadísticamente significativas en su conjunto, y los signos de los coeficientes concuerdan con la lógica propuesta. También se determinó la magnitud de los efectos que las variables producían, concluyendo que las variables Participación en el capital (PC) y Contrato superior a un año (CS1A), tenían mayor influencia que las demás. Una vez realizado este primer análisis sobre los modelos obtenidos, se debió determinar cuál de ellos, en forma teórica y práctica es el que mejor realiza la estimación, y se seleccionó como el mejor estimador de la probabilidad del uso de instrumentos públicos al modelo Logit, debido únicamente a su simplicidad matemática en comparación con el modelo Probit. En el caso del modelo Logit fue posible determinar las probabilidad de cada individuo mediante uso de planillas de cálculo, y de esta manera se corroboraron los resultados, lo que no fue posible hacer con el modelo Probit

Platinum and Gold Catalysis: à la Carte Hydroamination of Terminal Activated Allenes with Azoles

Nucleophilic additions to allenes catalyzed by transition metals represent a powerful tool to get selective access to diverse structures with numerous applications. Reported here is a straightforward methodology to achieve selective addition of azoles to the proximal or distal carbon of activated allenes depending on the catalyst used, unravelling a gold-platinum bimetallic catalysis approach for the 1,3-double addition of azoles to activated allenes to give 1,3-bisazole derivatives, important scaf-fold in medicinal and organometallic chemistry

Allene-derived gold and platinum complexes: synthesis and first applications in catalysis

We report here the synthesis, full characterisation and first application in catalysis of novel Au(I), Au(III) and Pt(II) carbene-type complexes formed from bis(pyridyl)allenes. The catalytic activity of the new Au(I)-complexes in the cylisation of 1,6-enynes, benchmark reaction for new Au and Pt complexes, was comparable to Au(I)-state-of-the-art catalysts used in these reactions. Reactions with the new Au(III)- and Pt(II)-complexes ocurred under milder conditions than the reported with AuCl3 and PtCl2

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements