José Paulo Santos

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The aim of this study is to evaluate the elemental composition of six food supplements of plant origin, commonly sold in the Portuguese market, by energy dispersive X-ray fluorescence. The presence of arsenic in all the Maca, Ashwagandha, Camu-Camu and Hemp protein samples (except the generic form) is a reason of concern due to the long-term effects of As mainly in its inorganic form. Thus, great caution must be taken on some food supplements, particularly the cases of Moringa from Egypt and Yellow/Xpresso Maca, whose inorganic As concentrations are in line with the upper bound concentration for the 95th dietary exposure according to the European Food Safety Authority which is 0.64 μg/kg bw/day. In what regards Hemp protein, if the supplier’s daily intake recommendation (30 g) is followed, values as high as 1.75 μg/kg bw/day of inorganic As will be consumed, which are dangerously above the upper bound. In this case this specific supplement lot should be removed from the market. Also the consumption of Hemp protein leads to a daily intake of Mn above the Daily Reference Intake (DRI) and Adequate Intakes (AIs) for adults. The contamination of Goji berries by Pb is a reason for concern—organic berries contained 11.3 μg/g while berries derived from conventional agriculture 11.6 μg/g, leading to daily intake doses of 315.3 μg and 324.8 μg, respectively, if the recommended daily intake of 28 g is followed. Our findings point out to an inadequacy of the recommended intakes by the supplier vis a vis the concentrations observed, greatly increasing the risk for public health.

We study the most important processes for the creation of excited states in He-like through C- like praseodymium ions from the ions ground configurations, leading to the emission of K X-ray lines. Theoretical values for inner-shell excitation and ionization cross sections, transition probabilities and energies for the deexcitation processes, are calculated in the framework of the multi-configuration Dirac- Fock method, including QED corrections. Using these calculated values, a theoretical Kα X-ray spectrum is obtained, which is compared to recent experimental data obtained in the Livermore Super-EBIT electron beam ion trap facility.

We study the most important processes for the creation of excited states in He-like through C- like praseodymium ions from the ions ground configurations, leading to the emission of K X-ray lines. Theoretical values for inner-shell excitation and ionization cross sections, transition probabilities and energies for the deexcitation processes, are calculated in the framework of the multi-configuration Dirac- Fock method, including QED corrections. Using these calculated values, a theoretical Kα X-ray spectrum is obtained, which is compared to recent experimental data obtained in the Livermore Super-EBIT electron beam ion trap facility.

Theoretical expressions for ionization cross sections by electron impact based on the binary encounter Bethe (BEB) model, valid from ionization threshold up to relativistic energies, are proposed.The new modified BEB (MBEB) and its relativistic counterpart (MRBEB) expressions are simpler than the BEB (nonrelativistic and relativistic) expressions because they require only one atomic parameter, namely the binding energy of the electrons to be ionized, and use only one scaling term for the ionization of all sub-shells.The new models are used to calculate the K-, L- and M-shell ionization cross sections by electron impact for several atoms with Z from 6 to 83.Comparisons with all, to the best of our knowledge, available experimental data show that this model is as good or better than other models, with less complexity.

Theoretical expressions for ionization cross sections by electron impact based on the binary encounter Bethe (BEB) model, valid from ionization threshold up to relativistic energies, are proposed.
The new modified BEB (MBEB) and its relativistic counterpart (MRBEB) expressions are simpler than the BEB (nonrelativistic and relativistic) expressions because they require only one atomic parameter, namely the binding energy of the electrons to be ionized, and use only one scaling term for the ionization of all sub-shells.
The new models are used to calculate the K-, L- and M-shell ionization cross sections by electron impact for several atoms with Z from 6 to 83. Comparisons with all, to the best of our knowledge, available experimental data show that this model is as good or better than other models, with less complexity.

Theoretical expressions for ionization cross sections by electron impact based on the binary encounter Bethe (BEB) model, valid from ionization threshold up to relativistic energies, are proposed.The new modified BEB (MBEB) and its relativistic counterpart (MRBEB) expressions are simpler than the BEB (nonrelativistic and relativistic) expressions because they require only one atomic parameter, namely the binding energy of the electrons to be ionized, and use only one scaling term for the ionization of all sub-shells.The new models are used to calculate the K-, L- and M-shell ionization cross sections by electron impact for several atoms with Z from 6 to 83. Comparisons with all, to the best of our knowledge, available experimental data show that this model is as good or better than other models, with less complexity.

Structure and QED effects for 2s1/2 and 2p3/2 levels are calculated for lithiumlike U89+ trough neonlike U82+, lithiumlike Th87+ trough neonlike Th80+ and lithiumlike Bi80+ trough neonlike Bi73+. The results of the first two sets are compared with recent measurements of the 2s1/2-2p3/2 transition energy in 3 to 10-electron ions. Good agreement with experiment is found for most of the observed lines. Forty-one possible transitions are calculated for each ion in the eight ionization states, in the experimental energy range. Twenty-eight of these transitions have not been observed, nor calculated previously. We also calculate transition rates, branching ratios, excitation and ionization cross sections and confirm that the thirteen experimental observed transitions correspond to the ones with highest relative intensities. However, we find nineteen more transitions that could be measured in a more sensitive experiment.X

A new expression for the total K-shell ionization cross section by electron impact based on the rela- tivistic extension of the binary encounter Bethe (RBEB) model, valid from ionization threshold up to relativistic energies, is proposed. The new MRBEB expression is used to calculate the K-shell ionization cross sections by electron impact for the selenium atom. Comparison with all, to our knowledge, available experimental data shows good agreement.

A new expression for the total K-shell ionization cross section by electron impact based on the rela- tivistic extension of the binary encounter Bethe (RBEB) model, valid from ionization threshold up to relativistic energies, is proposed. The new MRBEB expression is used to calculate the K-shell ionization cross sections by electron impact for the selenium atom. Comparison with all, to our knowledge, available experimental data shows good agreement.

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Following our previous study on spin–rotation and shielding constants of the SF6 molecule, the rotational g factor and the magnetic susceptibility are calculated here, using ab initio methods to evaluate the electronic contribution to the nuclear hyperfine constants, and compared with experimental results. It is shown, for the first time, that the electronic component of the rotational g factor is proportional to a constant, which is given by a sum over electronic states. We also evaluate for the SF6 molecule the indirect, or electron-coupled spin–spin interaction, theoretically described by Ramsey, and show that it gives non-negligible corrections to direct coupling constants d1 and d2. The contributions of the terms included in this interaction (DSO, PSO, SD and FC) are also analysed.

Following our previous study on spin–rotation and shielding constants of the SF6 molecule, the rotational g factor and the magnetic susceptibility are calculated here, using ab initio methods to evaluate the electronic contribution to the nuclear hyperfine constants, and compared with experimental results. It is shown, for the first time, that the electronic component of the rotational g factor is proportional to a constant, which is given by a sum over electronic states. We also evaluate for the SF6 molecule the indirect, or electron-coupled spin–spin interaction, theoretically described by Ramsey, and show that it gives non-negligible corrections to direct coupling constants d1 and d2. The contributions of the terms included in this interaction (DSO, PSO, SD and FC) are also analysed.

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We combined different experimental techniques with a theoretical approach to determine a consistent set of diagram lines energies and binding energies. We propose an original approach consisting in determining the mass attenuation coefficients in an energy range covering the L-, M- and N- absorption edges, including a detailed evaluation of the associated uncertainties, to derive precisely the binding energies. We investigated the Lα, Lβ and M spectra of Gd with an independantly calibrated high-resolution anti-parallel double-crystal x-ray spectrometer. All the lines were identified and found in excellent agreement with the binding energies previously derived. Morever, we identified for the first time M5−O2, M4−O2,3 and M4−N2,3 diagram lines.

The most important processes for the creation of chlorine ion excited states from the ground configurations of Cl 10+ to Cl 15+ ions in an electron cyclotron resonance ion source, leading to the emission of K x-ray lines, were studied. Theoretical values for inner-shell excitation and ionization cross-sections, including double KL and triple KLL ionization, transition probabilities and energies for the de-excitation processes, were calculated in the framework of the multi-configuration Dirac–Fock method. With reasonable assumptions about the electron energy distribution, a theoretical Kα x-ray spectrum was obtained, which was then compared with recent experimental data.

The most important processes for the creation of chlorine ion excited states from the ground configurations of Cl 10+ to Cl 15+ ions in an electron cyclotron resonance ion source, leading to the emission of K x-ray lines, were studied. Theoretical values for inner-shell excitation and ionization cross-sections, including double KL and triple KLL ionization, transition probabilities and energies for the de-excitation processes, were calculated in the framework of the multi-configuration Dirac–Fock method. With reasonable assumptions about the electron energy distribution, a theoretical Kα x-ray spectrum was obtained, which was then compared with recent experimental data.

The most important processes for the creation of S12+ to S14+ ions excited states from the ground configurations of S9+ to S14+ ions in an electron cyclotron resonance ion source, leading to the emission of K x-ray lines, are studied. Theoretical values for inner-shell excitation and ionization cross sections, including double-KL and triple-KLL ionizations, transition probabilities and energies for the de-excitation processes, are calculated in the framework of the multiconfiguration Dirac-Fock method. With reasonable assumptions about the electron energy distribution, a theoretical Kalpha x-ray spectrum is obtained, which is compared to recent experimental data.

The most important processes for the creation of S12+ to S14+ ions excited states from the ground configurations of S9+ to S14+ ions in an electron cyclotron resonance ion source, leading to the emission of K x-ray lines, are studied. Theoretical values for inner-shell excitation and ionization cross sections, including double-KL and triple-KLL ionizations, transition probabilities and energies for the de-excitation processes, are calculated in the framework of the multiconfiguration Dirac-Fock method. With reasonable assumptions about the electron energy distribution, a theoretical Kalpha x-ray spectrum is obtained, which is compared to recent experimental data.

Talanta, 155 + (2016) 107-115. doi:10.1016/j.talanta.2016.04.028