RESUMO
Elastic low-energy electron collisions with methyl formate have been studied theoretically at the level of various theories. The elastic integral cross section was calculated using Schwinger multichannel and R-matrix methods, in the static-exchange and static-exchange plus polarization levels of approximations for energies up to 15 eV. The absolute total cross section for electron scattering from methyl formate has been measured in a wide energy range (0.2-300 eV) using a 127° electron spectrometer working in the linear transmission configuration. The integral elastic and the absolute total cross sections display a π* shape resonance at around 1.70-1.84 eV, which can be related to the resonance visible for formic acid, and a broad structure located at 7-8 eV, which can be associated to a superposition of σ* shape resonances. Our results were compared with theoretical and experimental results available in the literature and with the results of electron collisions with formic acid. The additivity rule was used to estimate the total cross section of methyl formate and the results agree well with the experimental data.
RESUMO
War has always brought millions of silent non-human victims but the scale of this suffering is often either unknown, neglected or difficult to quantify. Further, the complexities associated with long-term and large-scale monitoring of marine species make it difficult to assess the impacts of war and the mortality of cetaceans resulting from warfare has not been investigated. Here we propose the use of a modified form of citizen science, namely gathering the information from social media. Dolphin stranding is such a poignant incident for most people, that the probability of eyewitness posting information on social media appears high. We test this idea by collecting data on cetacean strandings along the Black Sea published on the Internet over the three months of Russia's invasion of Ukraine in 2022. We also validate this method with a small-scale scientific study on cetacean mortality during the same period of time, conducted in 'Tuzlivski lymany' Nature National Park in Ukraine. Our dual approach has produced similar results, indicating a dramatic increase in cetacean mortality due to war operations in the Black Sea. We advocate the future use of social media to bridge the knowledge gap on the impacts of war on animals, in particular cetaceans.
Assuntos
Mídias Sociais , Animais , Cetáceos , UcrâniaRESUMO
Absolute grand-total cross section for electron scattering from titanium tetrachloride, TiCl4, molecule was measured at electron-impact energies ranging from 0.3 to 300 eV, in the linear electron-transmission experiment. The elastic integral, differential, momentum transfer, and total ionization cross sections for TiCl4 molecule were also calculated for low and intermediate collisional energies at the level of various theories. The low-energy elastic integral, differential, and momentum transfer cross sections were calculated with the Schwinger multichannel method implemented with pseudopotentials, in the static-exchange and static-exchange plus polarization levels of approximation, for energies up to 30 eV. The integral cross section calculated for low-energy electron scattering with the R-matrix method within the static-exchange and static-exchange plus polarization approximations for energies up to 15 eV are also reported. By the inspection of the cross sections, the presence of resonances is discussed. In particular, the calculated integral cross sections and the measured total cross section display a minimum at around 1 eV, which is consistent with the presence of a Ramsauer-Townsend minimum and a sharp increase at low energies, which is consistent with the presence of a virtual state. Additionally, interactions in elastic and ionization channels for intermediate collision energies were investigated with the additivity rule and the binary-encounter-Bethe methods.
