Chiral symmetry and meson exchange approach to hypernuclear decay

We take an approach to the $\Lambda$ nonmesonic weak decay in nuclei based on the exchange of mesons under the guidelines of chiral Lagrangians. The one pion and one kaon exchange are considered, together with the exchange of two pions, either correlated, leading to an important scalar-isoscalar exchange ($\sigma$-like exchange), or uncorrelated (box diagrams). A drastic reduction of the OPE results for the $\Gamma_n/\Gamma_p$ ratio is obtained and the new results are compatible with all present experiments within errors. The absolute rates obtained for different nuclei are also in fair agreement with experiment.Comment: 10 pages, 3 figs. Talk given at the Hypernuclear Conference 2000, Torin

Selective CO2/CH4 Separation by Fixed-Bed Technology Using Encapsulated Ionic Liquids

The performance of encapsulated ionic liquid (ENIL) sorbents has been experimentally evaluated in CO2/CH4 separation by means of gravimetric and fixed-bed measurements. Six ionic liquids (ILs) with CO2 chemical absorption ([Emim][Acetate], [Bmim][Acetate], [P66614][CNPyr], [Bmim][GLY], [Bmim][MET], and [Bmim]- [PRO]) were selected for the selective separation of CO2 from CH4. ENIL materials were prepared by encapsulation of these ILs in synthesized carbon submicrocapsules, achieving a ∼70% in mass of IL. Fixed-bed experiments of CO2 capture were carried out to evaluate the CO2/CH4 separation performance of prepared ENIL materials at different CO2 partial pressures and 303 K. Both thermodynamics and kinetics of CO2 sorption were analyzed. The experimental CO2 and CH4 isotherms in ENIL materials obtained from fixed-bed experiments were successfully compared to those obtained by reliable gravimetric tests and fitted to the Langmuir− Freundlich equilibrium model. In addition, experimental CO2 breakthrough curves were well-described by the linear driving force and Yoon and Nelson kinetic models, providing sorption rate constants. ENIL sorbents show high CO2 uptake capacity, comparable to conventional adsorbents, but with drastically higher selectivity, in concordance with the negligible CH4 solubility in ILs at the used operating conditions, with acetate-based ENIL materials being the best sorbents in thermodynamic terms. The obtained kinetic parameters revealed that the CO2 chemical sorption with ENIL materials overcomes the IL mass transfer limitations. The sorption rates are faster than those obtained with ENIL using IL physical absorbents and seem to be controlled by the reaction kinetics. The [P66614][CNPyrr]-based ENIL is found to be the most promising material, combining favorable kinetic and thermodynamic considerations for future development of CO2/CH4 separation using fixed-bed technologyThe authors are grateful to Ministerio de Ciencia e Innovación of Spain (projects PID2020-118259RB-I00 and PDC2021- 120881-I00) and Comunidad de Madrid (project P2018/ EMT4348) for financial support and Centro de Computación Científica de la Universidad Autónoma de Madrid for computational facilitie

Techno-economic feasibility of ionic liquids-based CO2 chemical capture processes

A techno-economic assessment of Ionic Liquids (ILs)-based post-combustion, biogas and pre-combustion CO2 chemical capture processes was carried out using Aspen Plus and Aspen Process Economic Analyzer (APEA). This cost estimation procedure is newly integrated to our COSMO-based/Aspen Plus methodology used to design the chemical absorption processes with 90% of CO2 capture. The equipment investment and variable operating cost were analyzed relating to the process operating conditions and the IL performance. The total annualized cost was used as the index to economically evaluate the processes at three CO2 treatment capacities and employing three different ILs: [P2228][CNPyr], [P66614][CNPyr] and [Bmim][acetate]. It benefits from economy of scale as well as it is directly related to both IL enthalpy of reaction and process gap capacity, being [P2228][CNPyr] -which has the most exothermic reaction and highest gap capacity- the solvent achieving the lowest costs. Current results indicate that operating at vacuum pressure to better regenerate the IL entails a remarkable cost penalty. Hence, both capital (CAPEX) and operational expenses (OPEX) could be reduced to achieve a total cost of 81.32 $/tCO2 for [P2228][CNPyr] in post-combustion CO2 capture when regenerating the IL at atmospheric pressure and 121.5 °C. Three IL pricing basis were considered when calculating the solvent cost. A conservative IL scaled up price of 50$/kg only increments around 5% the total annualized cost of the processThe authors are grateful to Ministerio de Economía y Competitividad of Spain (project CTQ2017-89441-R) and Comunidad de Madrid (project P2018/EMT4348) for financial support and Centro de Computación Científica de la Universidad Autónoma de Madrid for computational facilitie

Final State Interactions in Hadronic D decays

We show that the large corrections due to final state interactions (FSI) in the D^+\to \pi^-\pi^+\pi^+, D^+_s\to \pi^-\pi^+\pi^+, and D^+\to K^-\pi^+\pi^+ decays can be accounted for by invoking scattering amplitudes in agreement with those derived from phase shifts studies. In this way, broad/overlapping resonances in S-waves are properly treated and the phase motions of the transition amplitudes are driven by the corresponding scattering matrix elements determined in many other experiments. This is an important step forward in resolving the puzzle of the FSI in these decays. We also discuss why the \sigma and \kappa resonances, hardly visible in scattering experiments, are much more prominent and clearly visible in these decays without destroying the agreement with the experimental \pi\pi and K\pi low energy S-wave phase shifts.Comment: 22 pages, 6 figures, 5 tables. Minor changes. We extend the discusion when quoting a reference and we include a new one. Some typos are fixe

Direct Air Capture based on ionic liquids: from molecular design to process assessment

Direct air capture is a key carbon dioxide removal technology to mitigate climate change and keep the global average temperature rise below 1.5-2 °C. This work addresses for the first time the use of ionic liquids for direct air capture connecting their material design by molecular simulation to process modelling. First, 26 different ionic liquids were designed through quantum chemical calculations and their isotherms were computed to identify those with a positive cyclic working capacity at conditions relevant for direct air capture. Then, the most promising ionic liquids were assessed via process simulations in Aspen Plus. A wide range of operating configurations were screened by modifying the key process variables: air velocity (1 – 3 m/s), solvent mass flow (5 – 50 t/h) and temperature (293 – 323 K), and regeneration pressure (0.1 – 1 bar) and temperature (373 – 393 K). Exergy, energy and productivity were computed to detect optimal operating conditions; moreover, a simplified economic analysis was carried out to highlight the major cost components. The direct air capture system based on [P66614][Im] exhibited the most exergy (5.44 – 16.73 MJ/kg) and energy (15.15 – 35.42 MJ/kg) efficiency for similar productivity (0.5 – 1.3 kg/(m3·h)) thanks to its enhanced cyclic capacity (0.6 – 0.3 mol/kg). The minimum exergy required by [P66614][Im]-based DAC process is slightly better than alkali scrubbing (6.21 MJ/kg) and in line with amine (5.59 MJ/kg) scrubbing. In addition, the assessed DAC process has a theoretical potential to operate in the range of 200 $/tCO2 under reasonable energy and plant expenses. We conclude this work providing guidelines to address future development of direct air capture technologies based on ionic liquids

Enterprise Ionic Liquids Database (ILUAM) for Use in Aspen ONE Programs Suite with COSMO-Based Property Methods

“This document is the Accepted Manuscript version of a Published Work that appeared in final form in Industrial & Engineering Chemistry Research copyright © American Chemical Society after peer review and technical editing by the publisher . To access the final and published work see Enterprise Ionic Liquids Database (ILUAM) for Use in Aspen ONE Programs Suite with COSMO-Based Property Methods V. R. Ferro, C. Moya, D. Moreno, R. Santiago, J. de Riva, G. Pedrosa, M. Larriba, I. Diaz, and J. Palomar Industrial & Engineering Chemistry Research 2018 57 (3), 980-989 DOI: 10.1021/acs.iecr.7b04031An enterprise database of pure ionic liquids (ILs) for its use in the Aspen ONE programs is presented. The database is identified as ILUAM, and the first version (ILUAM01) contains 100 ILs composed of 30 cations and 23 anions. The IL components were introduced in Aspen Properties as pseudocomponents using information from the computational COSMO-RS method and from experimental viscosity data. ILUAM database was created to be used along with the COSMOSAC property model implemented in Aspen Plus, allowing evaluating IL process performance without needing further experimental data. Some validation tests were carried out to demonstrate the successful incorporation of ILs in the Aspen Plus property system. Then, the performance of ILUAM01 database in thermodynamic property predictions of mixtures involving ILs and conventional chemical compounds was revised in terms of activity coefficients at infinite dilution and phase equilibrium data. The property description of pure ILs and IL mixtures with conventional chemical compounds using COSMO-based/Aspen Plus approach was found with the accuracy level required in the conceptual design of new processes. ILUAM database offers the opportunity of performing systematic evaluation of potential industrial applications of ILs and their competitiveness as alternative to conventional solvents.The authors are grateful to the Comunidad de Madrid (project S2013- MAE-2800) and to the Ministerio de Economía y Competitividad of Spain (Project CTQ2014-52288-R) for financial support. M. Larriba also thanks Ministerio de Economía y Competitividad of Spain for awarding him a Juan de la Cierva-Formación Contract (Reference FJCI-2015-25343

η→π0γγ\eta \to \pi^0 \gamma \gamma decay within unitarized chiral perturbation theory

We improve the calculations of the $\eta \to \pi^0 \gamma \gamma$ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the $a_0(980)$ resonance and fixing the longstanding sign ambiguity on its contribution. This also allows us to calculate the loops with one vector meson exchange, thus removing a former source of uncertainty. In addition we ensure the consistency of the approach with other processes. First, by using vector meson dominance couplings normalized to agree with radiative vector meson decays. And, second, by checking the consistency of the calculations with the related $\gamma \gamma \to \pi^0 \eta$ reaction. We find an $\eta \to \pi^0 \gamma \gamma$ decay width of $0.47\pm 0.10$ eV, in clear disagreement with published data but in remarkable agreement with the most recent measurement.Comment: 15 pages, 10 figures, published versio

Pion and Kaon Vector Form Factors

We develop a unitarity approach to consider the final state interaction corrections to the tree level graphs calculated from Chiral Perturbation Theory ($\chi PT$) allowing the inclusion of explicit resonance fields. The method is discussed considering the coupled channel pion and kaon vector form factors. These form factors are then matched with the one loop $\chi PT$ results. A very good description of experimental data is accomplished for the vector form factors and for the $\pi\pi$ P-wave phase shifts up to $\sqrt{s}\lesssim 1.2$ GeV, beyond which multiparticle states play a non negligible role. In particular the low and resonance energy regions are discussed in detail and for the former a comparison with one and two loop $\chi PT$ is made showing a remarkable coincidence with the two loop $\chi PT$ results.Comment: 20 pages, 7 figs, to appear in Phys. Rev.

rho(omega)-> pi^0 pi^0 gamma, rho(omega) -> eta pi^0 gamma decays in the local quark Nambu--Jona-Lasinio model

The branching ratios and photon spectra of the rare processes rho(omega)-> pi^0 pi^0 gamma, rho(omega) -> eta pi^0 gamma are calculated in the framework of the standard local quark Nambu--Jona-Lasinio (NJL) model. Three types of diagrams are considered: the quark box and the pole diagrams with scalar (sigma,a_0(980)) and vector (rho,omega) mesons. The obtained estimations for the widths of the processes rho(omega)-> pi^0 pi^0 gamma are in satisfactory agreement with existing experimental data. Predictions are made for the widths of the processes rho(omega) -> eta pi^0 gamma.Comment: 6 pages, 5 figure