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Valence and Rydberg excitations of 3-fluorotoluene in the 4.4–10.8 eV photoabsorption energy region
Publication . Bandeira, E.; Kumar, S.; Lozano, A. I.; Bettega, M. H. F.; Hoffmann, S. V.; Jones, N. C.; Souza Barbosa, A.; Limão-Vieira, P.; CeFITec – Centro de Física e Investigação Tecnológica; DF – Departamento de Física; PERGAMON-ELSEVIER SCIENCE LTD
The absolute photoabsorption cross sections for 3-fluorotoluene in the 4.4–10.8 eV energy-range were obtained for the first-time using a synchrotron radiation light source. New theoretical calculations, providing vertical excitation energies and oscillator strengths, were performed at the time-dependent density functional theory and the equation-of-motion coupled cluster method restricted to single and double excitations to qualitatively support the experimental data. The electronic transitions discernible in the photoabsorption spectrum have been assigned to valence, mixed valence-Rydberg and Rydberg transitions. Additionally, a comprehensive assignment of the vibronic structure was performed with the main contribution of C–H in plane bending mode progressions dictating the spectroscopy of the lowest-lying absorption band. From the absolute photoabsorption cross sections, the photolysis lifetimes of 3-fluorotoluene in the Earth's atmosphere were also obtained.
PARP1
Publication . Conceição, Carlota J.F.; Moe, Elin; Ribeiro, Paulo A.; Raposo, Maria; Instituto de Tecnologia Química e Biológica António Xavier (ITQB); LIBPhys-UNL; Faculdade de Ciências e Tecnologia (FCT); Elsevier
The Poly (ADP-ribose) polymerase-1 (PARP1) enzyme is involved in several signalling pathways related to homologous repair (HR), base excision repair (BER), and non-homologous end joining (NHEJ). Studies demonstrated that the deregulation of PARP1 function and control mechanisms can lead to cancer emergence. On the other side, PARP1 can be a therapeutic target to maximize cancer treatment. This is done by molecules that can modulate radiation effects, such as DNA repair inhibitors (PARPi). With this approach, tumour cell viability can be undermined by targeting DNA repair mechanisms. Thus, treatment using PARPi represents a new era for cancer therapy, and even new horizons can be attained by coupling these molecules with a nano-delivery system. For this, drug delivery systems such as liposomes encompass all the required features due to its excellent biocompatibility, biodegradability, and low toxicity. This review presents a comprehensive overview of PARP1 biological features and mechanisms, its role in cancer development, therapeutic implications, and emerging cancer treatments by PARPi-mediated therapies. Although there are a vast number of studies regarding PARP1 biological function, some PARP1 mechanisms are not clear yet, and full-length PARP1 structure is missing. Nevertheless, literature reports demonstrate already the high usefulness and vast possibilities offered by combined PARPi cancer therapy.
Multi-Fresnel-Lens Pumping Approach for Simultaneous Emission of Seven TEM00-Mode Beams with 3.73% Conversion Efficiency
Publication . Costa, Hugo; Liang, Dawei; Matos, Ana; Almeida, Joana; CeFITec – Centro de Física e Investigação Tecnológica; DF – Departamento de Física; MDPI - Multidisciplinary Digital Publishing Institute
TEM00-mode operation is a requirement in many laser-based applications due to the small divergence and high-power density of the emitted laser beam. A solar laser scheme was designed and numerically studied with the goal of increasing the solar-to-laser power conversion efficiency in the TEM00-mode operation. The collection and primary concentration of sunlight was performed via twelve sets of folding mirrors and Fresnel lenses, toward a laser head composed of a fused silica torus volume and seven Ce:Nd:YAG rods, in a side-pump configuration. With this scheme, TEM00-mode laser power totaling 212.39 W could potentially be produced from seven beams, with six of them being 32.60 W each and with (Formula presented.) = 1.00, (Formula presented.) = 1.01 quality factors. Notably, 35.40 W/m2 collection efficiency and, most importantly, 3.73% solar-to-laser power conversion efficiency were numerically achieved. The latter efficiency value represents a 1.81-time improvement over the experimental record, established with a prototype that had a single Ce:Nd:YAG rod in an end-side pump configuration.
SF6 Negative Ion Formation in Charge Transfer Experiments
Publication . Kumar, Sarvesh; Hoshino, Masamitsu; Kerkeni, Boutheïna; Garcia, Gustavo; Ouerfelli, Ghofrane; Al-Mogren, Muneerah Mogren; Limão-Vieira, Paulo; CeFITec – Centro de Física e Investigação Tecnológica; DF – Departamento de Física; MDPI - Multidisciplinary Digital Publishing Institute
In the present work, we report an update and extension of the previous ion-pair formation study of Hubers, M.M.; Los, J. Chem. Phys. 1975, 10, 235–259, noting new fragment anions from time-of-flight mass spectrometry. The branching ratios obtained from the negative ions formed in K + SF6 collisions, in a wide energy range from 10.7 up to 213.1 eV in the centre-of-mass frame, show that the main anion is assigned to SF5− and contributing to more than 70% of the total ion yield, followed by the non-dissociated parent anion SF6− and F−. Other less intense anions amounting to <20% are assigned to SF3− and F2−, while a trace contribution at 32u is tentatively assigned to S− formation, although the rather complex intramolecular energy redistribution within the temporary negative ion is formed during the collision. An energy loss spectrum of potassium cation post-collision is recorded showing features that have been assigned with the help of theoretical calculations. Quantum chemical calculations for the lowest-lying unoccupied molecular orbitals in the presence of a potassium atom are performed to support the experimental findings. Apart from the role of the different resonances participating in the formation of different anions, the role of higher-lying electronic-excited states of Rydberg character are noted.
Ring strain integrity in the absorption spectrum of β-propiolactone
Publication . Randi, P. A. S.; Bettega, M. H. F.; Jones, N. C.; Hoffmann, S. V.; Zuin, L.; Macdonald, M.; Mason, N. J.; Śmiałek, M. A.; Limão-Vieira, P.; DF – Departamento de Física; CeFITec – Centro de Física e Investigação Tecnológica; Elsevier
New absolute cross-section values are reported from high-resolution vacuum ultraviolet (VUV) photoabsorption measurements of β-propiolactone in the photon energy range 4.6–10.8 eV (268–115 nm). The assignment of the different vibronic features has been performed with the aid of quantum chemical calculations that provide vertical energies, oscillator strengths and harmonic frequencies. The joint experimental and theoretical methodology employed provides a comprehensive review of the electronic state spectroscopy of CH2CH2CO2. A photoelectron spectrum has also been recorded from 10 up to 24 eV and compared to earlier data in the literature. A new value of (10.560 ± 0.002) eV for the ground ionic state adiabatic ionisation energy is recommended. The vibrational features in the spectral bands are assigned to C=O stretching, v3′a′, CH2 wagging, v6′a′, ring C–O stretching, v10′a′, and C=O in-plane bending, v13′a′ modes. Potential energy curves for the lowest-lying electronic excited states, as a function of the C–O/C=O coordinates, have been obtained from time-dependent density functional theory (TD-DFT). Ring strain integrity is shown to be a fragile mechanism upon electronic excitation. The calculations have also shed light on the relevant internal conversion from the electronic excited states governing the nuclear dynamics with significant pre-dissociative character of the lowest-lying electronic states.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
Concurso de avaliação no âmbito do Programa Plurianual de Financiamento de Unidades de I&D (2017/2018) - Financiamento Base
Número da atribuição
UIDB/00068/2020