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We present a combined experimental and theoretical study of single-photon ionization of 9-methyladenine (9MA) in the gas phase. In addition to tautomerism, several rotamers due to the rotation of the methyl group may exist. Computations show, however, that solely one rotamer contributes because of low population in the molecular beam and/or unfavorable Franck–Condon factors upon ionization. Experimentally, we used VUV radiation available at the DESIRS beamline of the synchrotron radiation facility SOLEIL to record the threshold photoelectron spectrum of this molecule between 8 and 11 eV. This spectrum consists of a well-resolved band assigned mainly to vibronic levels of the D0 cationic state, plus a contribution from the D1 state, and two large bands corresponding to the D1, D2 and D3 electronically excited states. The adiabatic ionization energy of 9MA is measured at 8.097 ± 0.005 eV in close agreement with the computed value using the explicitly correlated coupled cluster approach including core valence, scalar relativistic and zero-point vibrational energy corrections. This work sheds light on the complex pattern of the lowest doublet electronic states of 9MA+. The comparison to canonical adenine reveals that methylation induces further electronic structure complication that may be important to understand the effects of ionizing radiation and the charge distribution in these biological entities at different time scales.

Hospitals outsource several activities of the service support in order to focus on the core healthcare production as maintenance service. Recently, faced to the sophistication and the costs of medical equipment that continue to escalate, governments have implemented new reforms to control costs and improve the efficiency and the quality. Hospitals become interested in minimizing the total operational cost, by optimizing healthcare production planning and their support activities. Reorganizing the medical equipment maintenance service becomes a priority for the hospital managers to reduce the cost and the dependency on external parties while ensuring that the medical devices are safe, accurate, and operating at the required level of performance. In this article, we propose an efficient procedure to take the appropriate decisions for medical equipment maintenance such as the selection of maintenance strategy, the insourcing/outsourcing, and the selection of contracts’ type and content. A practical application of this procedure in the Tunisian context is considered. Nevertheless, our procedure is general and can be tailored to hospitals in both developed and developing countries.

The hospital is a world that is both sensitive and complex, sensitive because the human life is involved and complex because medical facilities are growing in number and in technical complexity. Then, the problem of the medical equipment maintenance in order to keep them in safe, reliable and with high level of availability has become a major preoccupation of the hospital. The objective of this thesis is to provide tools to help the biomedical maintenance service of the hospital to make decisions that allow a better control of costs, while ensuring patient and user safety and maintaining optimal performance of medical equipment. First, a heuristic has been proposed for the choice of internalization or outsourcing maintenance and for the selection of the appropriate contract. The selection of the contract is based on a set of criteria while considering the available budget constraint. Then, to improve the proposed procedure, we proposed multi-criteria decision-making tools to select the appropriate maintenance strategies. Seven criteria have been designed to study the criticality of medical equipment and the choice of maintenance by providing a coupling of the AHP approach "Analytical Hierarchy Process" with TOPSIS technique "Technique for Order Performance by Similarity to Ideal Solution." As the expert judgments of the maintenance department presented some uncertainty, we integrated the fuzzy language assessment of the criticality of the equipment and the selection of the maintenance strategy (Fuzzy AHP coupled with Fuzzy TOPSIS). A mixed integer linear programming model (MILP) was developed to define thresholds of criticality to characterize the three maintenance strategies. According to these thresholds, maintenance cost can be optimized within the available budget. Finally, a second mixed integer linear programming model (MILP) was developed based on the proposed heuristic. This model allows selecting for each equipment, the maintenance strategy, the internalization or the outsourcing of the maintenance and the type of contract while considering the available budget and the workload / capacity of the maintenance department, Le milieu hospitalier est un monde à la fois sensible et complexe, sensible parce que la vie humaine est en jeu et complexe parce que les équipements médicaux augmentent en nombre et en complexité technique. Ainsi, afin de préserver le bon état de fonctionnement de ces équipements et à un niveau élevé de disponibilité, leur entretien est devenu l'une des préoccupations majeures des responsables de l’hôpital. L’objectif de cette thèse est de proposer, aux responsables de maintenance biomédicale dans les établissements de soins, des outils d’aide à la décision qui permettent une meilleure maitrise des coûts. Ceci en assurant la sécurité des patients et des utilisateurs et en maintenant des performances optimales de l’ensemble des équipements médicaux. Tout d’abord, une heuristique a été proposée pour le choix de l’internalisation ou de l’externalisation de la maintenance et pour la sélection du contrat adéquat. La sélection du contrat est basée sur un ensemble de critères tout en considérant la contrainte du budget disponible. Ensuite, afin d’améliorer la procédure proposée, nous avons proposé des outils d’aide à la décision multicritère pour le choix adéquat d’une stratégie de maintenance. Pour l’étude de la criticité des équipements médicaux et le choix de la maintenance, sept critères ont été étudiés en proposant un couplage de l’approche AHP « Analytical Hierarchy Process » à la technique TOPSIS « Technique for Order Performance by Similarity to Ideal Solution ». Comme les experts du service de maintenance présentaient une certaine incertitude dans leurs jugements, nous avons intégré l’évaluation linguistique floue dans l’étude de la criticité des équipements et dans la sélection de la stratégie de maintenance (Fuzzy AHP couplée avec Fuzzy TOPSIS). Un modèle mathématique MILP a été développé pour la définition des limites de la criticité afin de caractériser les trois stratégies de maintenance. Le bon choix de ces limites permet d’optimiser le coût de la maintenance en respectant le budget disponible. Enfin, un deuxième modèle mathématique MILP a été développé en se basant sur l’heuristique proposée. Ce modèle permet de sélectionner pour chaque équipement, la stratégie de maintenance, internaliser ou externaliser la maintenance et le type du contrat tout en considérant le budget disponible et la charge/capacité du service maintenance

The state-to-state photodissociation of CO2 is investigated in the VUV range of 11.94-12.20 eV by using two independently tunable vacuum ultraviolet (VUV) lasers and the time-sliced velocity-map-imaging-photoion (VMI-PI) method. The spin-allowed CO(X(1)Σ(+); v = 0-18) + O((1)D) and CO(X(1)Σ(+); v = 0-9) + O((1)S) photoproduct channels are directly observed from the measurement of time-sliced VMI-PI images of O((1)D) and O((1)S). The total kinetic energy release (TKER) spectra obtained based on these VMI-PI images shows that the observed energetic thresholds for both the O((1)D) and O((1)S) channels are consistent with the thermochemical thresholds. Furthermore, the nascent vibrational distributions of CO(X(1)Σ(+); v) photoproducts formed in correlation with O((1)D) differ significantly from that produced in correlation with O((1)S), indicating that the dissociation pathways for the O((1)D) and O((1)S) channels are distinctly different. For the O((1)S) channel, CO(X(1)Σ(+); v) photoproducts are formed mostly in low vibrational states (v = 0-2), whereas for the O((1)D) channel, CO(X(1)Σ(+); v) photoproducts are found to have significant populations in high vibrationally excited states (v = 10-16). The anisotropy β parameters for the O((1)D) + CO(X(1)Σ(+); v = 0-18) and O((1)S) + CO(X(1)Σ(+); v = 0-9) channels have also been determined from the VMI-PI measurements, indicating that CO2 dissociation to form the O((1)D) and O((1)S) channels is faster than the rotational periods of the VUV excited CO2 molecules. We have also calculated the excited singlet potential energy surfaces (PESs) of CO2, which are directly accessible by VUV excitation, at the ab initio quantum multi-reference configuration interaction level of theory. These calculated PESs suggest that the formation of CO(X(1)Σ(+)) + O((1)S) photoproducts occurs nearly exclusively on the 4(1)A' PES, which is generally repulsive with minor potential energy ripples along the OC-O stretching coordinate. The formation of CO(X(1)Σ(+)) + O((1)D) photofragments can proceed by non-adiabatic transitions from the 4(1)A' PES to the lower 3(1)A' PES of CO2via the seam of conical intersections at a near linear OCO configuration, followed by the direct dissociation on the 3(1)A' PES. The theoretical PES calculations are consistent with the experimental observation of prompt CO2 dissociation and high rotational and vibrational excitations for CO(X(1)Σ(+)) photoproducts.

Highly correlated ab initio methods are used to investigate the lowest electronic states of doublet and quartet spin multiplicities for SNO. One-dimensional cuts of the three-dimensional potential energy surfaces (3D-PESs) of these electronic states along the stretch and bend coordinate are calculated. Several avoided crossings and conical intersections are located for bent and linear configurations. The dynamics on the excited electronic states of SNO are very complex, and suggest that multi-step mechanisms should occur to populate the ground state via radiationless processes or lead to predissociation. In addition, our calculations show that the ground (X̃(2)A(')) and the first excited (Ã(2)A(")(Π)) states of this radical form a linear-bent Renner-Teller system. They correlate to the SNO(1(2)Π) state at linearity. Systematic studies of both components are performed using standard coupled cluster approaches, explicitly correlated coupled cluster technique, and multi-configurational methods in connection with large basis sets. Core-valence and scalar relativistic effects are examined. For both electronic states, the 3D-PESs are mapped in internal coordinates at the RCCSD(T)-F12b∕cc-pVTZ-F12 level. The analytical representations of these potential energy surfaces are incorporated later into perturbative and variational treatments of the nuclear motions. A set of spectroscopic parameters and spin-rovibronic levels calculated variationally are presented. Strong anharmonic resonances are found. These new results allow for the reassignment of earlier experimental IR bands of SNO trapped in cooled argon matrices.

Accurate ab initio calculations are performed to investigate the stable isomers of MgO 3 and its lowest electronic states at both molecular and asymptotic regions. The calculations are done using large basis sets and configuration interaction methods including the complete active space self-consistent field, the internally contracted multi-reference configuration interaction, the standard coupled cluster (RCCSD(T)) approaches and the newly implemented explicitly correlated coupled cluster method (RCCSD(T)-F12). The presence of three stable forms is predicted: a cyclic global minimum c-MgO 3, which is followed by a quasi-linear isomer, l2-MgO 3. A third isomer of C s symmetry (l1-MgO 3) is also found. Moreover, we computed the one-dimensional cuts of the six-dimensional potential energy surfaces of the lowest doublet and quartet electronic states of MgO 3 along the R MgO and R OO stretching coordinates covering both the molecular and the asymptotic regions. These curves are used later for discussing the metastability of this cation and to propose plausible mechanisms for the Mg O 3 atmospherically important ion-molecule reaction and related reactive channels. © 2012 American Institute of Physics., This work has been supported by the PCI program of AECID-MAE of Spain, project PCI A/5107/06. M. L. Senent acknowledges the Ministerio de Educación of Spain for the grant (Grant No. AYA2008-00446 and for computing resources of CESGA. M.H. thanks a financial support from the PCMI program (INSU, CNRS).

National audience

International audience; We used ab initio methodology for the computation of the potential energy curves of the doublet and quartet electronic states of the MgO(+) cation correlating with the four lowest dissociation limits. Using these highly correlated wavefunctions, we calculated their spin-orbit coupling and transition moments. We deduced an accurate set of spectroscopic constants for this cation. Most of the data relative to the electronic excited states of this cation are predictive in nature. Moreover, our potentials, transition moments and spin-orbit coupling evolutions are incorporated into Fermi golden rule calculations to deduce the natural lifetimes of the lowest MgO(+)(1(2)Sigma(+)) ro-vibrational levels. Finally, our potentials were used for the prediction of the single ionization spectrum of MgO.

International audience; We used multiconfigurational methods and a large basis set to compute the potential energy curves of the valence and valence-Rydberg electronic states of MgO molecule. New bound electronic states are found. Using these highly correlated wave functions, we evaluated their mutual spin-orbit couplings and transition moment integrals. For the bound electronic states of MgO, we deduced an accurate set of spectroscopic constants that agree remarkably well with experimental results. Moreover, our potentials, transition moments, and spin-orbit coupling evolutions are incorporated into Fermi golden rule calculations to deduce the radiative lifetimes of MgO(B (1)Sigma(+)) rovibrational levels and the natural lifetimes of MgO(A (1)Pi) vibrational levels, where a good agreement is found with experimental values. Finally, we suggest new routes for the production of cold Mg and O atoms and cold MgO molecules. (C) 2010 American Institute of Physics. [doi:10.1063/1.3498900]

Highly correlated ab initio methods are used to investigate the lowest MgO2 + electronic states. Our computations confirm the existence of the strongly bent (MgO2 + over(X, ∼)2 A2) form and the weakly bound l - MgOO+ (over(X, ∼)4 Σ-) charge quadrupole complex. For both isomers, the three-dimensional potential energy surfaces (3D-PESs) of their electronic ground states are mapped in internal coordinates not far from their respective equilibrium geometries. Then a set of spectroscopic parameters is derived using second order perturbation theory. The rovibrational spectra are also deduced variationally. One-dimensional cuts of the 3D-PESs of the lowest doublet and quartet electronic states of MgO2 + along the RMgO and ROO stretchings and bending are calculated, covering both the molecular and the asymptotic regions. These curves are used later for discussing the metastability of this cation and to propose a plausible mechanism for the Mg+ + O2 atmospheric ion-molecule reaction. © 2008 Elsevier B.V. All rights reserved., M.H. would like to thank a visiting fellowship at CSIC (Spain) during the preparation of this work. The Project A/8083/07 CSICUniversity of Tunis El Manar (AECI-MAE, Spain) and the Project AYA2005-00702 (MEC, Spain) are acknowledged for financial supports.

The maintenance department in a hospital is responsible for ensuring the safety of medical equipment and their availability while keeping the operation costs minimal. The selection of the best maintenance strategy is a key decision to reduce the equipment downtime, increase the availability, and bring down the maintenance costs. In this paper, we use an integrated approach that includes several tools from the literature, namely, the Analytical Hierarchy Process (AHP), the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), and the mathematical optimization (especially mixed integer problems MILP) to provide the decision maker of the maintenance department with an entire solution to the problem at hand. These three tools are introduced to 1) determine the criticality of medical equipment based on a multi-criteria analysis, 2) rank the different maintenance strategies based on their (benefits) importance to the hospital and 3) select the optimal maintenance strategy for each device while keeping the total maintenance costs within a predetermined budget. We applied our approach to a case study at the Hospital of “Habib Bourguiba” in Tunisia, and the numerical results show the efficiency of our approach to improve the availability and the reliability of high risk medical devices.

Several examples are presented in order to illustrate the crucial role of high spin multi- plicity electronic states on the formation and decomposition of the corresponding molec- ular systems. For instance, these states are good candidates where electronically excited, metastable negative ions can be found. Moreover, they are needed in order to explain fully unimolecular and bimolecular reaction pathways. During these reactions, the importance of the couplings between these states, such as vibronic and Renner-Teller, and with the states of lower spin multiplicity, such as spin-orbit, are pointed out.

International audience

International audience; Highly correlated ab initio methods were used in order to generate the potential-energy curves of the SO+ electronic states correlating to S+(S-4(u))+O(P-3(g)) and S+(D-2(u))+O(P-3(g)). These curves were used for deducing accurate spectroscopic properties for these electronic states. Our calculations predict the existence of a (2)Phi state lying close in energy to the well-characterized b (4)Sigma(-) state and several weakly bound quartet and doublet states located in the 6-9 eV internal energy range not identified yet. The spin-orbit integrals between these electronic states were evaluated using these highly correlated wave functions, allowing the discussion of the metastability and the predissociation processes forming S++O in their electronic ground states. Multistep spin-orbit-induced predissociation pathways are suggested. More specifically, the experimentally determined dissociative potential-energy curve [H. Bissantz , Z. Phys. D 22, 727 (1992)] proposed to explain the rapid SO+(b (4)Sigma(-),v >= 13)-> S+(S-4(u))+O(P-3(g)) reaction is found to coincide with the 2 (4)Pi potential-energy curve for short internuclear distances and with the repulsive 1 (6)Pi state for longer internuclear separations. (c) 2006 American Institute of Physics.

International audience; Highly correlated ab initio methods were used in order to generate the potential energy curves of the electronic states of the SO2+ dication and of the electronic ground state of the neutral SO molecule. These curves were used to predict the spectroscopic properties of this dication and to perform forward calculations of the double photoionization spectrum of SO. In light of spin-orbit calculations, the metastability of this doubly charged ion is discussed: for instance, the rovibrational levels of the X (1)Sigma(+) and A (3)Sigma(+) states are found to present relatively long lifetimes. In contrast, the other electronic excited states should predissociate to form S+ and O+ in their electronic ground states. The simulated spectrum shows structures due to transitions between the v=0 vibrational level of SO (X (3)Sigma(-)) and the vibrational levels below the barrier maximum of 11 of the calculated electronic states. The 2 (1)Sigma(+) electronic state of SO2+ received further treatment: in addition to vibrational bands due to the below barrier energy levels of this electronic state, at least nine continuum resonances were predicted which are responsible for the special shape of the spectrum in this energy region. This work is predictive in nature and should stimulate future experimental investigations dealing with this dication. (C) 2005 American Institute of Physics.

International audience