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  • Park et al expanded their own model as hydrogen

    2021-02-20

    Park et al. [34] expanded their own model as hydrogen- bonding lattice fluid EOS (NLF-HB) [35] for calculating the activity coefficients of aqueous amino PD123319 solution. Further, Pazuki et al. [36] extended the perturbed hard chain theory which has been proposed by Beret and Prausnitz [37] for modeling the solute activity coefficient and solubility of aqueous amino acid solutions. Besides the mentioned EOSs, the PHSC EOS [38] has attracted many researchs in order to model different thermodynamic properties of associating and polar systems [39], [40]. Valavi et al. [41] investigated the potential of PHSC EOS [38] to predict the water activities, osmotic coefficients, and vapor pressure of single solutions containing amino acids. Likewise, the solubility of aqueous amino acid mixtures was correlated applying additional adjustable parameters. Recently, we have used CPA EOS to calculate aqueous amino acid solutions density, activity coefficient, vapor pressure, and solubility, without considering the dissociation/association equilibria and dependency of solubility on pH value [42]. The model also has been utilized to correlate the Δh and Δs through the optimization of 6 amino acids solubility data.
    Thermodynamic modeling
    Results and discussion
    Conclusions
    Introduction Following early clinical observations [1], [4], many experimental studies have been conducted on postural adjustments associated with voluntary movement (for a review, see [8]). “Anticipatory” (APAs), “simultaneous” (SPAs) and “consecutive” (CPAs) postural adjustments have been identified. Most studies have focused on APAs, which precede the onset of voluntary movement. Until recently, less attention had been paid to consecutive postural adjustments (CPAs), the postural adjustments that occur after the end of a voluntary movement. They are generated internally [8], unlike those resulting from external percussion (for instance, a slap on the back). Since the first experimental study conducted on shoulder flexion [12], CPAs have been investigated in terms of unilateral reach [7], [16], [17], bilateral reach [27], [31], [35], ramp push [22], [23], single stepping [25], [26], and ball kicking [30]. Most of them [12], [23], [25], [26] have focused on a biomechanical approach and considered kinetic variables (currently impulse, duration or peak amplitude) in the reaction forces or center of pressure displacement. Some studies have been based mainly on the EMGs of postural muscles (i.e., the excitation level or timing) [27], [31], [35]. Results have identified the influence of task-movement parameters (velocity, load), postural conditions (support base) and functional state (fatigue, impairment) on CPAs. However, results remain too limited to allow elaboration of a synthesis; nor are they sufficient to provide a clear understanding of the role of CPAs. Thus, the current study aims to offer new insights into CPAs. Our study is based on two classical physiological concepts. The first is the concept of voluntary movement, according to which movements are termed “voluntary” when they are achieved with the aim of performing a given task; for instance, pointing at a target, or pushing against an object. The task, which is specified by its parameters (i.e., amplitude, velocity, force, and precision), provides a performance evaluation. In other words, a voluntary movement is part of a motor act, which can be defined as a more general process underlying the achievement of a given task. The second concept is the partitioning of motor control into a focal and a postural component. This concept was put forward by Gelfand et al. (1966) [18] who revisited the ideas of Bernstein (1935) [6]. Thus, the former component refers to the body segments that are mobilized to perform the voluntary movement, and the latter refers to the body parts that are involved in the stabilizing reactions. Body partitioning between a “focal chain” and a “postural chain” [10] is a direct consequence of this assumption. As the current task was to hit a target with the index finger, the voluntary movement was to move the upper limb in order to accomplish the task. Therefore, the simplest option was to consider that the focal chain corresponds to the upper limb, and the postural chain to the rest of the body. This assumption was supported by earlier experimental data on the same paradigm [16], [17], [24], [29], [32] and by classical data gathered on functional anatomy or motor physiology.