A combined experimental and theoretical study has been carried out on 4‐fluoro‐threonine, the only naturally occurring fluorinated amino acid. Fluorination of the methyl group significantly increases ...the conformational complexity with respect to the parent amino acid threonine. The conformational landscape has been characterized in great detail, with special attention given to the inter‐conversion pathways between different conformers. This led to the identification of 13 stable low‐energy minima. The equilibrium population of so many conformers produces a very complicated and congested rotational spectrum that could be assigned through a strategy that combines several levels of quantum chemical calculations with the principles of machine learning. Twelve conformers out of 13 could be experimentally characterized. The results obtained from the analysis of the intra‐molecular interactions can be exploited to accurately model fluorine‐substitution effects in biomolecules.
Fluorinated α‐amino acids have been attracting increasing attention, but their structure in the gas‐phase has not been investigated yet. Fluorination has a negligible impact on steric properties, but has a dramatic effect on the electronic properties. 4‐fluoro‐threonine has been efficiently synthesized in large amount and its conformational landscape has been disentangled through a combination of experiment and theory beyond the state of the art.
Purpose
The need for prolonged invasive mechanical ventilation in COVID-19 patients is placing the otorhinolaryngologist in front of an increasing request for tracheostomy. Nowadays, there is ...uncertainty regarding the timing of tracheostomy, the prognosis of these patients and the safety of healthcare workers. The aim of this study is to evaluate the efficacy and safety of tracheostomy placement in patients with COVID-19.
Methods
A retrospective cohort study on 23 COVID 19 patients, to analyse the timing of tracheostomy, the risk factors associated with in-hospital death and the infection of the involved health care workers. Early tracheostomy was defined as ≤ 10 days and late ones > 10 days.
Results
The mortality rate of COVID-19 patients admitted to ICU that underwent tracheostomy was 18%. The overall mortality of patients admitted to ICU was 53%. The univariate analysis revealed that early tracheostomy, SOFA score > 6, and D-dimer level > 4 were significantly associated with a greater risk of death. At the multivariate analysis SOFA score > 6 and D-dimer level > 4 resulted as significant factors for a higher risk of death. No health care workers associated with tracheostomy are confirmed to be infected by SARS-CoV2.
Conclusion
We suggest to wait at least 14 days to perform tracheostomy. In patients with SOFA score > 6 and D dimer > 4, tracheostomy should not be performed or should be postponed. Optimized procedures and enhanced personal protective equipment can make the tracheostomy safe and beneficial in COVID-19 patients.
In this contribution, we present a multiscale and multidisciplinary VR architecture that aims at creating a common environment where cultural heritage and chemistry meet in order to strengthen the ...role already played by chemistry in the process of restoration of cultural goods. Our aim is to create a user friendly platform where experts of both fields can share data and ideas in a direct way, in order to achieve deeper insights into cultural goods combining the scientific and historical points of view. As a case study we present the 3D reconstruction of the "Sala degli Stemmi", which is one of the two historical rooms at Palazzo della Carovana in Pisa, presenting a number of artworks that underwent a process of chemical analysis and restoration in 2012. The whole architecture has been developed using the Unity game engine, and it is usable with HTC Vive headsets. The implementation of the VR environment and the potential applications, from both the scientific and educational points of view, are discussed in some detail.
Hard red winter wheat kernels were infested with eggs of
Rhyzopertha dominica. After 20
d, when the larvae reached the fourth instar, they were killed by exposing the infested kernels to phosphine ...gas for 24
h. The infested kernels were then divided into four portions and treated as follows: one portion was immediately frozen at −80
°C to avoid myosin degradation; the other three portions were kept at 32
°C and 65% relative humidity, and then frozen at −80
°C after 14, 28, and 56
d post-fumigation, respectively. Each treatment was replicated five times. Myosin was measured using a commercial enzyme linked immunosorbent assay (ELISA) method that specifically detects this protein (Biotect
®, Austin, TX). Myosin degradation was most rapid in the first 2 weeks after the larvae were killed, decreasing from 1.672 to 0.695
ng/well during this period (a 58.4% reduction). There were no significant differences in myosin degradation between samples that were 14, 28, and 56
d post-fumigation. Grain is often fumigated to control insects. Frequently, this occurs many weeks before the grain is milled and may be repeated during the storage period. Therefore, estimates using the ELISA test may underestimate internal insect infestation because of myosin degradation. Insect fragment estimates for previously fumigated grain could be underestimated by as much as 58%.
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