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A common valence force field for polycyclic aromatic hydrocarbons (PAHs) and graphite has been used in order to explain their Raman spectra from a unified viewpoint. On this basis the correlation observed between experimental spectra has been explained and rationalized. Quantum chemical density functional theory calculations of Raman intensities of small PAHs have been also performed, supporting the conclusions obtained from the dynamical analysis. The results obtained are useful for the characterization of materials containing graphitic domains and provide some new insight on the nature of the D peak in disordered graphite.

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This paper presents the Mechanical Ventilator Milano (MVM), a novel intensive therapy mechanical ventilator designed for rapid, large-scale, low-cost production for the COVID-19 pandemic. Free of moving mechanical parts and requiring only a source of compressed oxygen and medical air to operate, the MVM is designed to support the long-term invasive ventilation often required for COVID-19 patients and operates in pressure-regulated ventilation modes, which minimize the risk of furthering lung trauma. The MVM was extensively tested against ISO standards in the laboratory using a breathing simulator, with good agreement between input and measured breathing parameters and performing correctly in response to fault conditions and stability tests. The MVM has obtained Emergency Use Authorization by U.S. Food and Drug Administration (FDA) for use in healthcare settings during the COVID-19 pandemic and Health Canada Medical Device Authorization for Importation or Sale, under Interim Order for Use in Relation to COVID-19. Following these certifications, mass production is ongoing and distribution is under way in several countries. The MVM was designed, tested, prepared for certification, and mass produced in the space of a few months by a unique collaboration of respiratory healthcare professionals and experimental physicists, working with industrial partners, and is an excellent ventilator candidate for this pandemic anywhere in the world.

Abstract. The atmospheric chemistry of 2,2,5,5-tetramethyloxolane (TMO), a promising ‘green’ solvent replacement for toluene, was investigated in laboratory and computational experiments. Results from both absolute and relative rate studies demonstrated that the reaction OH + TMO (R1) proceeds with a rate coefficient k1(296 K) = (3.1 ± 0.4) × 10−12 cm3 molecule−1 s−1, a factor of three smaller than predicted by recent structure activity relationships. Quantum chemical calculations (CBSQB3-G4) demonstrated that the reaction pathway via the lowest-energy transition state was characterised by a hydrogen-bonded pre-reaction complex, leading to thermodynamically less favoured products. Steric hindrance from the four methyl substituents in TMO prevent formation of such H-bonded complexes on the pathways to thermodynamically favoured products, a likely explanation for the anomalous slow rate of (R1). Further evidence for a complex mechanism was provided by k1(294 – 502 K), characterised by a local minimum at around T = 340 K. An estimated atmospheric lifetime of ≈ 3 days was calculated for TMO, approximately 50 % longer than toluene, indicating that any air pollution impacts from TMO emission would be less localised. Relative rate experiments were used to determine a rate coefficient, k2(296 K) = (1.2 ± 0.1) × 10−10 cm3 molecule−1 s−1 for Cl + TMO (R2); together with the slow (R1) this may indicate an additional contribution to TMO removal in regions impacted by high levels of atmospheric chlorine. All results indicate that TMO is a less problematic volatile organic compound (VOC) than toluene.