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  • br Methods br Results Our study focused on consecutive

    2020-03-21


    Methods
    Results Our study focused on consecutive postural adjustments (CPAs) between IS and BS (the shaded areas on Fig. 2); that is to say, the Rx kinetics that occur after the end of an upper limb movement. It was dedicated to examining the main features of CPAs and the influence of movement velocity on these features. Qualitative and quantitative data were gathered.
    Discussion This study focuses on consecutive postural adjustments (CPAs), that is, the postural adjustments that occur after the end of a voluntary movement (the shaded areas on 2). It takes into account original findings on Rx (the antero-posterior component of the reaction forces). Three main results emerged:
    Conclusion Furthermore, both CPAs and APAs vary as a function of task velocity. Thus, it can be assumed that postural chain kinetics are programmed according to task velocity. However, CPAs and APAs differ in terms of certain features. Indeed, even if CPA and APA impulses are scaled according to the same movement parameter (in this study, velocity), they are scaled in a different way (i.e., in their duration and amplitude). Thus, we can envisage a trade-off between CPA amplitude and duration, depending on movement velocity and balance parameters. Above all, while APAs are proactive and, therefore, programmed, CPAs are post-active, but not necessarily reactive in strict reflex terms. According to Gelfand et al. [18] and other authors, such as Latash [20], a feedback process could be integrated in a more global process, where postural and focal control mechanisms are assumed to cooperate. In addition to our findings on CPA and APA, an earlier study of SPA kinetics has shown that the postural chain plays a dual role when performing the same motor act, with one or both roles depending on a time-instant in the kinetic sequence [17].
    Disclosure of interest
    Introduction Among Xylometazoline HCl fuels, natural gas is the cleanest, in terms of CO2 emission, burn efficiency and amount of air pollutant [1]. Methane is the prevailing element of natural gas; therefore, it contains other volatile molecules and a variety of impurities. In fact, it contains usually considerable amounts of acid gases (CO2, H2S) which can lead to corrosion in equipment and pipelines if water is present. Mercaptans (mainly Methyl Mercaptan (MM) and Ethyl mercaptan (EM)) are known as toxic molecules with undesirable odour, and fuel combustion of mercaptans and other sulphur components can produce SO2 which is an undesirable chemical, and they can cause environmental issues. Acid gases and mercaptans are needed to be removed from natural gas until they reach acceptable standard. The treated natural gas contains a maximum of 2% of CO2, 2–4 ppm of H2S and 5–30 ppm of total mercaptans [2]. Chemical absorption with alkanolamines [3] (such as monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA)) is the most well-established method to separate acid gas from natural gas. Acid gases react with alkanolamines in the absorber via acid-base chemical reactions to form electrolyte species. Mercaptans and hydrocarbons do not react with alkanolamines molecules, and they are physically absorbed by aqueous alkanolamine solutions. Thermodynamic models are of high importance for the design of the process, as they are linked directly to the accurate determination of the Vapor-Liquid Equilibrium and energy balances. Reliable thermodynamic models can allow designers not only to confirm their regulatory limits, but also to determine the best operation minimizing the loss of valuable hydrocarbons components. Our aim in this study is to develop an accurate thermodynamic model to describe alkane, aromatic and mercaptans solubilities (methane, ethane, propane, n-butane, n-pentane, n-hexane, benzene, toluene, MM, EM) in aqueous alkanolamine solutions, to estimate acid gases (CO2, H2S) solubilities in aqueous alkanolamine solutions, and to estimate other crucial properties such as electrolytes concentration and vapor phase composition (mostly water content).