The COVID-19 pandemic and its global effects on dental practice. An international survey

Objectives: A multicentre survey was designed to evaluate the impact of COVID-19 outbreak on dental practice worldwide, estimate the COVID-19 related symptoms/signs, work attitudes and behaviour and the routine use of protective measures and Personal Protective Equipment (PPE). Methods: A global survey using a standardized questionnaire with research groups from 36 countries was designed. The questionnaire was developed and pretested during April 2020 and contained three domains: 1) Personal data; 2) COVID-19 positive rate and symptoms/signs presumably related to the coronavirus; 3) Working conditions and PPE adopted after the outbreak. Countries’ data were grouped by the Country Positive Rate (CPR) during the survey period and by Gross-National-Income per capita. An ordinal multinomial logistic regression model was carried out with COVID-19 self-reported rate referred by dental professionals as dependent variable to assess the association with questionnaire items. Results: A total of 52,491 questionnaires were returned with a male/female ratio of 0.63. Out of the total respondents, 7,859 dental professionals (15%) reported symptoms/signs compatible with COVID-19. More than half of the sample (n = 27,818; 53%) stated to use FFP2/N95 masks, while 21,558 (41.07%) used eye protection. In the bivariate analysis, CPR and N95/FFP2 were significantly associated (OR = 1.80 95%CI = 1.60/2.82 and OR = 5.20 95%CI = 1.44/18.80, respectively), while Gross-National-Income was not statistically associated with CPR (OR = 1.09 95%CI = 0.97/1.60). The same significant associations were observed in the multivariate analysis. Conclusions: Oral health service provision has not been significantly affected by COVID-19, although access to routine dental care was reduced due to country-specific temporary lockdown periods. While the dental profession has been identified at high-risk, the reported rates of COVID-19 for dental professionals were not significantly different to those reported for the general population in each country. These findings may help to better plan oral health care for future pandemic events

The COVID-19 pandemic and its global effects on dental practice. An international survey

Objectives A multicentre survey was designed to evaluate the impact of COVID-19 outbreak on dental practice worldwide, estimate the COVID-19 related symptoms/signs, work attitudes and behaviour and the routine use of protective measures and personal protective equipment (PPE). Methods A global survey using a standardized questionnaire with research groups from 36 countries was designed. The questionnaire was developed and pretested during April 2020 and contained three domains: 1) personal data; 2) COVID-19 positive rate and symptoms/signs presumably related to the coronavirus; 3) working conditions and PPE adopted after the outbreak. Countries’ data were grouped by the country positive rate (CPR) during the survey period and by Gross-National-Income per capita. An ordinal multinomial logistic regression model was carried out with COVID-19 self-reported rate referred by dental professionals as dependent variable to assess the association with questionnaire items. Results A total of 52,491 questionnaires were returned with a male/female ratio of 0.63. Out of the total respondents, 7,859 dental professionals (15%) reported symptoms/signs compatible with COVID-19. More than half of the sample (n=27,818; 53%) stated to use FFP2/N95 masks, while 21,558 (41.07%) used eye protection. In the bivariate analysis, CPR and N95/FFP2 were significantly associated (OR=1.80 95%CI=1.60/2.82 and OR=5.20 95%CI=1.44/18.80, respectively), while Gross-National-Income was not statistically associated with CPR (OR=1.09 95%CI=0.97/1.60). The same significant associations were observed in the multivariate analysis. Conclusions Oral health service provision has not been significantly affected by COVID-19, although access to routine dental care was reduced due to country-specific temporary lockdown periods. While the dental profession has been identified at high-risk, the reported rates of COVID-19 for dental professionals were not significantly different to those reported for the general population in each country. These findings may help to better plan oral health care for future pandemic events

Degradation of haloaromatic compounds

An ever increasing number of halogenated organic compounds has been produced by industry in the last few decades. These compounds are employed as biocides, for synthetic polymers, as solvents, and as synthetic intermediates. Production figures are often incomplete, and total production has frequently to be extrapolated from estimates for individual countries. Compounds of this type as a rule are highly persistent against biodegradation and belong, as "recalcitrant" chemicals, to the class of so-called xenobiotics. This term is used to characterise chemical substances which have no or limited structural analogy to natural compounds for which degradation pathways have evolved over billions of years. Xenobiotics frequently have some common features. e.g. high octanol/water partitioning coefficients and low water solubility which makes for a high accumulation ratio in the biosphere (bioaccumulation potential). Recalcitrant compounds therefore are found accumulated in mammals, especially in fat tissue, animal milk supplies and also in human milk. Highly sophisticated analytical techniques have been developed for the detection of organochlorines at the trace and ultratrace level

Etude expérimentale de la fissuration dynamique de plaques (application à la fragmentation de réservoirs )

La rupture dynamique des réservoirs métalliques pressurisés résulte de la compétition entre la fissuration de la paroi et la sortie du fluide qui en est à l origine. Pour comprendre ce phénomène, deux études expérimentales ont été mises en œuvre. La première a consisté à soumettre des plaques métalliques à des chargements sous forme d explosions, et à examiner leur mode de fissuration. Les vitesses de fissuration semblent indépendantes du chargement, tandis que la taille des fragments augmente avec la violence de l explosion. La deuxième a consisté à faire exploser des enceintes d environ vingt litres. Elle a permis de confirmer une partie des tendances observées précédemment.ORLEANS-BU Sciences (452342104) / SudocBOURGES-ENS Ingénieurs (180332301) / SudocSudocFranceF

Studies of Homogeneously and Heterogeneously Catalyzed Liquid Phase Reactions in Micro Systems with Application to Esterification

A microplant concept is introduced for the analysis of homogeneously and heterogeneously catalyzed liquid phase reactions. Esterification of acetic acid with butanol is considered as a benchmark problem. The plant configuration includes a micromixer (SIMMV-2, IMM Mainz, Germany), which mixes the reactants fed at the reaction temperature (200C, 60-800C) followed by the microreactor. For the case of homogeneously catalyzed esterification, a long tube of 1mm inner diameter acted as the reaction tube with reasonable residence time. The results from the experiments for the range of temperature and the different catalyst concentrations were consistent with the published literature. For the case of hererogeneously catalyzed esterification a micro fixed bed reactor ( FBR) was designed by stacking and connecting several reaction plates on which several micro-channels were created through micro-machining. Amberlyst-15 was used a catalyst and filled in the reactor channels (1.43m total length). The pressure drop across the length of the reactor was not very high even in the swollen condition of the catalyst particle. The reactor gave excellent conversion rates at steady state and the performance of the FBR was consistent for very long time (over 42hrs of continuous operation). A change in the residence/reaction time and the reactive length was achieved by changing the total flow rate and the number of reaction plates, respectively. The microplant is flexible in terms of desired residence time, amount of the catalyst, particle size and the flow rates. The FBR developed in this investigation offered the following advantages: (i) the system can be maintained practically isothermal, (ii) due to the very long active life of the catalyst, the reactor needs not to be disassembled frequently, (iii) the mole ratio of the reactants can be modified externally, (iv) the system is suitable for the analysis of the dynamics of this adsorption enhanced reaction. (v) The concept is simple and yet gives flexibility in extending this design for achieving a continuous small-scale production facility