Photoexcited energy relaxation and vibronic couplings in π-conjugated carbon nanorings.

Conjugated carbon nanorings exhibit unique photophysical properties that, combined with their tunable sizes and conformations, make them suitable for a variety of practical applications. These properties are intimately associated to their strained, bent and sterically hindered cyclic structures. Herein we perform a comparative analysis of the photoinduced dynamics in carbon nanorings composed of nine phenyl units([9]CPP) and nine naphthyl units ([9]CN) respectively. The sterically demanding naphthyl units lead to large dihedral angles between neighboring units. Nevertheless, the ultrafast electronic and vibrational energy relaxation and redistribution is found to be similar for both systems. We observe that vibronic couplings, introduced by nonadiabatic energy transfer between electronic excited states, ensure the intramolecular vibrational energy redistribution through specific vibrational modes. The comparative impact of the internal conversion process on the exciton spatial localization and intra-ring migration indicates that naphthyl units in [9]CN achieve more efficient but less dynamical self-trapping compared to that of phenyl units in [9]CPP. That is, during the photoinduced process, the exciton in [9]CN is more static and localized than the exciton in [9]CPP. The internal conversion processes take place through a specific set of middle- to high-frequency normal modes, which directly influence the spatial exciton redistribution during the internal conversion, self-trapping and intra-ring migration.

Linfoma pleural primario asociado a piotórax / Pyothorax associated primary pleural lymphoma

RESUMEN: presentamos el caso de un paciente varón, exfumador, con antecedentes de empiema crónico de origen tuberculoso, que consultó por dolor torácico. Una tomografía computerizada (TC) demostró una pérdida de volumen en hemitórax derecho, con paquipleuritis calcificada asociada a colección hipodensa pleural, así como una lesión de partes blandas en contigüidad con la referida colección sugestiva de empiema necessitatis. En una tomografía por emisión de positrones (PET) se objetivó masa hipermetabólica de intensa captación en pared torácica derecha con afectación pleural. Se realizó biopsia guiada por TC con diagnóstico de linfoma no Hodgkin. El linfoma pleural primario representa el 7% de los casos de linfoma. Habitualmente afecta a pacientes con antecedentes de infección VIH o piotórax crónico. Los síntomas más frecuentes son disnea y dolor torácico. El diagnóstico se realiza mediante biopsia guiada o videotoracoscopia. El tipo histopatológico de linfoma pleural más descrito es el linfoma de células B grandes difuso

ABSTRACT: We present the case of a male patient, former smoker, with a history of chronic tuberculosis empyema, complaining of thoracic pain. A computerized tomography (CT) scan showed volume loss in the right hemithorax, with calcified pachypleuritis associated with hypodense pleural collection, as well as a soft tissue lesion contiguous with said collection, suggestive of empyema necessitans. A positron emission tomography (PET) scan showed a hypermetabolic mass with intense uptake on the right thoracic wall with pleural involvement. A CT-guided biopsy was done, obtaining a diagnosis of non-Hodgkin lymphoma. Primary pleural lymphoma accounts for 7% of all lymphoma cases. It normally affects patients with a history of HIV infection or chronic pyothorax. The most frequent symptoms are dyspnea and thoracic pain. Diagnosis is made using guided biopsy or videothoracoscopy. The most commonly described histopathological type of pleural lymphoma is diffuse large B-cell lymphoma

Influence of quantum effects on the physisorption of molecular hydrogen in model carbon foams.

The physisorption of molecular hydrogen in model carbon foams has been investigated from 50 K to room temperature. The study is carried out within the framework of the density functional theory for quantum liquids at finite temperatures. Calculations are performed in the grand canonical ensemble, i.e., the adsorbed fluid is assumed to be in equilibrium with an external gas of hydrogen molecules with concentrations ranging from 8×10(-4) kg m(-3) to n=71 kg m(-3). It is shown that, while strong zero-point energy effects are present even at room temperature, the adsorption isotherms exhibit only a weak dependence on the explicit incorporation of the bosonic exchange symmetry of hydrogen molecules. The increase of the average particle density prevents the deviations from the Maxwell-Boltzmann statistics to become noticeable if the system is cooled down. The volumetric storage capacity of these materials at low temperatures is about one half of the U. S. Department of Energy goal, while the gravimetric capacity is still far from the standards required by mobile applications. The relation between the microscopic structure of the hydrogen fluid and the calculated adsorption properties is also addressed.

Effective temperature representation of quantum delocalization effects on the dynamics of NO(A(2)Sigma(+) <--X(2)Pi(+)) photoexcitation in Ne matrices.

The energetics of the optical excitation of the lowest Rydberg state of a nitric oxide molecule embedded in a neon matrix and the subsequent rearrangement of the solid host are investigated by classical molecular dynamics simulations. Quantum delocalization effects are incorporated through an effective temperature. The relevance of the inclusion of the anharmonicity of crystal site oscillations in the calculation of the effective temperature is evaluated. We show that representing zero point vibrations beyond the harmonic approximation improves the correspondence between the results of molecular dynamics simulations and pump-probe experiments performed on this system. We explored both the steady state spectroscopy and the relaxation dynamics of the doped matrix in this improved representation. The analysis of the Fourier components of particle density reveals that the system simulated within the quantum thermal harmonic correction does not fulfill the translational symmetry of the host crystal.