Search

The authors acknowledge Professor Pedro M. P. Gois for support and constructive discussions, from the iMed.ULisboa – Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, Universidade de Lisboa. M.M., A.N., R.R. and F.F.S. acknowledge the Portuguese National Funding Agency FCT‐MCTES through research grant PTDC/FIS‐AQM/31215/2017. L.C. acknowledges financial support from São Paulo Research Foundation (FAPESP), under grant N.2020/04822‐9. This work was also supported by Radiation Biology and Biophysics Doctoral Training Programme (RaBBiT, PD/00193/2012); UID/FIS/00068/2020 (CEFITEC). Publisher Copyright: © 2022 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd. Rationale: 2,4,6-Tris(4-formylphenyl)boroxine (TFPB) is a substituted boroxine containing a benzaldehyde molecule bonded to each boron atom. Boroxine cages are an emerging class of functional nanostructures used in host–guest chemistry, and benzaldehyde is a potential radiosensitizer. Reactions initiated by low-energy electrons with such complexes may dictate and bring new fundamental knowledge for biomedical and pharmaceutical applications. Methods: The electron ionization properties of TFPB are investigated using a gas-phase electron–molecule crossed beam apparatus coupled with a reflectron time-of-flight mass spectrometer in an orthogonal geometry. Ionization and threshold energies are experimentally determined by mass spectra acquisition as a function of the electron energy. Results: The abundance of the molecular precursor cation in the mass spectrum at 70 eV is significantly lower than that of the most abundant fragment C7H5O+. Twenty-nine cationic fragments with relative intensities >2% are detected and identified. The appearance energies of six fragment cations are reported, and the experimental first ionization potential is found at (Formula presented.) eV. Moreover, eight double cations are identified. The present results are supported by quantum chemical calculations based on bound state techniques, electron ionization models and thermodynamic thresholds. Conclusions: According to these results, the TPFB properties may combine the potential radiosensitizer effect of benzaldehyde with the stability of the boroxine ring. publishersversion published

P30332 153377/2016‐0 304571/2018‐0 PTDC/FIS‐AQM/31215/2017 PD/00193/2012 UID/FIS/00068/2020 PD/BD/142768/2018 Ubiquinone molecules have a high biological relevance due to their action as electron carriers in the mitochondrial electron transport chain. Here, we studied the dissociative interaction of free electrons with CoQ0, the smallest ubiquinone derivative with no isoprenyl units, and its fully reduced form, 2,3-dimethoxy-5-methylhydroquinone (CoQ0H2), an ubiquinol derivative. The anionic products produced upon dissociative electron attachment (DEA) were detected by quadrupole mass spectrometry and studied theoretically through quantum chemical and electron scattering calculations. Despite the structural similarity of the two studied molecules, remarkably only a few DEA reactions are present for both compounds, such as abstraction of a neutral hydrogen atom or the release of a negatively charged methyl group. While the loss of a neutral methyl group represents the most abundant reaction observed in DEA to CoQ0, this pathway is not observed for CoQ0H2. Instead, the loss of a neutral OH radical from the CoQ0H2 temporary negative ion is observed as the most abundant reaction channel. Overall, this study gives insights into electron attachment properties of simple derivatives of more complex molecules found in biochemical pathways. publishersversion published

Ubiquinone molecules have a high biological relevance due to their action as electron carriers in the mitochondrial electron transport chain. Here, we studied the dissociative interaction of free electrons with CoQ

Part of the energy deposited in biological tissue by high-energy radiation is converted to secondary electrons. The knowledge at the molecular level on radiation interaction with biological species has increased due to the contributions of many different scientists working on radiation physics and radiation chemistry. The intention of this Special Issue on electron and photon interactions with (bio) molecules is to bring together different areas of knowledge that focus on radiation interactions with matter.

OBJETIVO: Associar a prevalência de Atividade Física com os hábitos alimentares em escolares de ambos os sexos com idades entre 11 a 17 anos em duas escolas públicas da cidade de Ponta Grossa, Paraná, Brasil. MÉTODOS: A amostra foi composta por 177 escolares de ambos os sexos, de duas escolas públicas da cidade de Ponta Grossa, utilizou-se o questionário WebCas, para analisar os dados foram distribuídos em medidas de tendência central e dispersão, e recorreu-se ao teste de Qui-quadrado. RESULTADOS: O número final do estudo foi de 153 participantes, sendo 52,9% do sexo masculino, com média de idade de 14,3 anos (±2,0). O nível de Atividade Física da amostra em geral foi insuficientemente ativo (63,4%). Em relação aos hábitos alimentares em uma proporção de consumo semanal, os percentuais mais elevados foram direcionados ao consumo adequado de refrigerantes (69,9%), doces (64,7%), salgados e frituras (81,7%), e ao consumo inadequado de frutas (60,8%) e verduras (53,6%). A associação do nível de Atividade Física aos hábitos alimentares apresentou resultados significativos ao consumo de refrigerantes (p=0,03). CONCLUSÃO: Conclui-se, sobre a atividade física insuficiente e o baixo consumo de frutas entre os escolares, porém a associação foi significativa com o nível de Atividade Física e o consumo de refrigerantes. Sugere-se novos estudos, especialmente de intervenção que abordem a influência do nível de Atividade Física e dos hábitos alimentares dos indicadores de saúde entre os escolares.ABSTRACT. Association between physical activity and eating habits in schoolchildren aged 11 to 17 years oldOBJECTIVE: To associate the prevalence of Physical Activity with eating habits in schoolchildren of both sexes aged between 11 and 17 years old in two public schools in the city of Ponta Grossa, Paraná, Brazil. METHODS: The sample consisted of 177 students of both sexes, from two public schools in the city of Ponta Grossa. The WebCas questionnaire was used for the analysis, the data were distributed in measures of central tendency and dispersion, and the test was used of Chi-square. RESULTS: The final number of the study was 153 participants, with 52.9% male, with a mean age of 14.3 years (±2.0). The physical activity level of the sample in general was insufficiently active (63.4%). In relation to eating habits in a proportion of weekly consumption, the highest percentages were directed to the adequate consumption of soft drinks (69.9%), sweets (64.7%), savory and fried foods (81.7%), and to inadequate consumption of fruits (60.8%) and vegetables (53.6%). The association of level of physical activity with eating habits showed significant results with the consumption of soft drinks (p=0.03). CONCLUSION: In conclusion, insufficient physical activity and low fruit consumption among students, however, the association was significant with the level of physical activity and consumption of soft drinks. New studies are suggested that address the influence of the level of physical activity and eating habits on the health indicators of schoolchildren.

Platinum coordination complexes have found wide applications as chemotherapeutic anticancer drugs in synchronous combination with radiation (chemoradiation) as well as precursors in focused electron beam induced deposition (FEBID) for nano-scale fabrication. In both applications, low-energy electrons (LEE) play an important role with regard to the fragmentation pathways. In the former case, the high-energy radiation applied creates an abundance of reactive photo- and secondary electrons that determine the reaction paths of the respective radiation sensitizers. In the latter case, low-energy secondary electrons determine the deposition chemistry. In this contribution, we present a combined experimental and theoretical study on the role of LEE interactions in the fragmentation of the Pt(II) coordination compound cis-PtBr2(CO)2. We discuss our results in conjunction with the widely used cancer therapeutic Pt(II) coordination compound cis-Pt(NH3)2Cl2 (cisplatin) and the carbonyl analog Pt(CO)2Cl2, and we show that efficient CO loss through dissociative electron attachment dominates the reactivity of these carbonyl complexes with low-energy electrons, while halogen loss through DEA dominates the reactivity of cis-Pt(NH3)2Cl2.

Secondary electrons with an energy distribution below 100 eV are formed when high-energy particles interact with matter. In the focused electron beam induced deposition, high-energy beams are used to decompose organometallic compounds on surfaces. We investigated the electron ionisation of WCl6 and dissociative electron attachment to WCl6 in the gas phase in order to better understand the decomposition mechanism driven by secondary electrons.A double-focusing mass spectrometer coupled with a Nier-type ion source was used to perform the present studies. The electron ionisation studies were performed with an electron energy of 70 eV and dissociative electron attachment studies in the energy range of ~0-14 eV.Tungsten hexachloride rapidly oxidises, leading to the formation of a mixture of pure WCl6 and WCl4 O together with WCl2 O2 species. The fragmentation of the three chlorinated compounds is effective, although electron ionisation to WCl6 leads to W(+) in contrast with WCl2 O2 and WCl4 O leading to WO2 (+) and WO(+) , respectively, as lighter fragments. With regard to electron attachment, decomposition of the precursor molecules is observed; however, W(-) was not detected within the detection limit of the instrument.Electron ionisation and dissociative electron attachment (DEA) to WCl6 , WCl4 O and WCl2 O2 lead to strong fragmentation. In electron ionisation, the fragmentation by loss of chlorine atoms was observed for both WCl6 and the oxidised species. Additionally, the loss of all chlorine ligands is observable for WCl6 as well as the oxidised species. The DEA results have shown dissociation by the scission of chlorine atoms as well as by the scission of an oxygen atom. The formation of chlorine and oxygen anions was observed, indicating the formation of a neutral counterpart containing the metal atom, free to be attacked by the next electron.

The interaction of low‐energy electrons with biomolecules plays an important role in the radiation‐induced alteration of biological tissue at the molecular level. At electron energies below 15 eV, dissociative electron attachment is one of the most important processes in terms of the chemical transformation of molecules. So far, a common approach to study processes at the molecular level has been to carry out investigations with single biomolecular building blocks like pyrimidine as model molecules. Electron attachment to single pyrimidine, as well as to pure clusters and hydrated clusters, was investigated in this study. In striking contrast to the situation with isolated molecules and hydrated clusters, where no anionic monomer is detectable, we were able to observe the molecular anion for the pure clusters. Furthermore, there is evidence that solvation effectively prevents the ring fragmentation of pyrimidine after electron capture.

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores - Major Automação. Faculdade de Engenharia. Universidade do Porto. 2008