Browsing by Issue Date, starting with "2018-09-03"
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- Eggshell waste to produce building lime: calcium oxide reactivity, industrial, environmental and economic implicationsPublication . Ferraz, Eduardo; Gamelas, José A. F.; Coroado, João; Monteiro, Carlos; Rocha, FernandoEggshells wastes are produced in huge amounts worldwide. The recycling or valorization of this waste, which otherwise is usually disposed in landfills, represents an opportunity within a circular economy perspective. In the present work, the potential of chicken eggshell waste to produce calcitic lime was explored. After collection from an industry supplier, the waste was thoroughly characterized for its mineralogical, chemical, and thermal properties. The material was calcined at 1000 °C, and the obtained calcium oxide was evaluated for its reactivity in wet slaking tests. Comparison was made with commercial limestone used as reference. It was found that the calcium oxide from eggshell waste belonged to the most reactive class (R5—60 °C within 10 min), the same of the calcium oxide from limestone. However, different times were obtained to reach 60 °C (25 s and 4:37 min:s) and for 80% of the reaction (28 s and 5 min) for calcium oxide from limestone and eggshell waste, respectively. The lower reactivity of calcium oxide from eggshell waste was related to its larger size particles with smoother surfaces and lower specific surface area in comparison to limestone calcium oxide. Industrial, environmental and economic implications concerning the use of this waste to produce lime were also evaluated. The eggshell waste could be all consumed at an industrial scale in Portugal allowing for approximately 2.6% partial substitution of limestone in a lime factory.
- Search for additional neutral MSSM Higgs bosons in the $\tau\tau$ final state in proton-proton collisions at $\sqrt{s}=$ 13 TeVPublication . CMS collaboration (2305 authors); Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Galinhas, Bruno; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Seixas, Joao; Strong, Giles; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, PasqualeA search is presented for additional neutral Higgs bosons in the τ τ final state in proton-proton collisions at the LHC. The search is performed in the context of the minimal supersymmetric extension of the standard model (MSSM), using the data collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{−1}$. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes production of the Higgs boson in association with b quarks. No significant deviation above the expected background is observed. Model-independent limits at 95% confidence level (CL) are set on the product of the branching fraction for the decay into τ leptons and the cross section for the production via gluon fusion or in association with b quarks. These limits range from 18 pb at 90 GeV to 3.5 fb at 3.2 TeV for gluon fusion and from 15 pb (at 90 GeV) to 2.5 fb (at 3.2 TeV) for production in association with b quarks, assuming a narrow width resonance. In the m$_{h}^{hod +}$ scenario these limits translate into a 95% CL exclusion of tan β > 6 for neutral Higgs boson masses below 250 GeV, where tan β is the ratio of the vacuum expectation values of the neutral components of the two Higgs doublets. The 95% CL exclusion contour reaches 1.6 TeV for tan β = 60.
- Measurement of the $\mathrm{Z}\gamma^{*} \to \tau\tau$ cross section in pp collisions at $\sqrt{s} = $ 13 TeV and validation of $\tau$ lepton analysis techniquesPublication . CMS collaboration (2276 authors); Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Galinhas, Bruno; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Seixas, Joao; Strong, Giles; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, PasqualeA measurement is presented of the $\mathrm {Z}/\gamma ^{*} \rightarrow \tau \tau $ cross section in $\text {pp}$ collisions at $\sqrt{s} = 13\hbox { TeV}$ , using data recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of $2.3\hbox { fb}^{-1}$ . The product of the inclusive cross section and branching fraction is measured to be $\sigma (\text {pp} \rightarrow \mathrm {Z}/\gamma ^{*}\text {+X}) \, \mathcal {B}(\mathrm {Z}/\gamma ^{*} \rightarrow \tau \tau ) = 1848 \pm 12\,(\text {stat}) \pm 67\text { (syst \,+\,lumi)}\text { pb} $ , in agreement with the standard model expectation, computed at next-to-next-to-leading order accuracy in perturbative quantum chromodynamics. The measurement is used to validate new analysis techniques relevant for future measurements of $\tau $ lepton production. The measurement also provides the reconstruction efficiency and energy scale for $\tau $ decays to hadrons $\,+\,\nu _{\tau }$ final states, determined with respective relative uncertainties of 2.2 and 0.9%.