Optimality Principles and Motion Planning of Human-Like Reaching Movements

The paper deals with modeling of human-like reaching movements. Several issues are under study. First, we consider a model of unconstrained reaching movements that corresponds to the minimization of control effort. It is shown that this model can be represented by the wellknown Beta function. The representation can be used for the construction of fractional order models and also for modeling of asymmetric velocity proï¬les. Next, we address the formation of boundary conditions in a natural way. From the mathematical point of view, the structure of the optimal solution is deï¬ned not only by the form of the optimality criterion but also by the boundary conditions of the optimization task. The natural boundary conditions, deï¬ned in this part of the paper, can also be used in modeling asymmetric velocity proï¬les. Finally, addressing the modeling of reaching movements with bounded control actions, we consider the minimum time formulation of the optimization problem and (for the n-th order integrator) ï¬nd its analytical solution

Effect of purification method of β-chitin from squid pen on the properties of β-chitin nanofibers

Published online 20 June 2016The relationship between purification methods of β-chitin from squid pen and the physicochemical properties of β-chitin nanofibers (NFs) were investigated. Two types of β-chitin were prepared, with β-chitin (a → b) subjected to acid treatment for decalcification and then base treatment for deproteinization, while β-chitin (b → a) was treated in the opposite order. These β-chitins were disintegrated into NFs using wet pulverization. The β-chitin (b → a) NF dispersion has higher transmittance and viscosity than the β-chitin (a → b) NF dispersion. For the first time, we succeeded in obtaining 3D images of the β-chitin NF dispersion in water by using quick-freeze deep-etch replication with high-angle annular dark field scanning transmission electron microscopy. The β-chitin (b → a) NF dispersion has a denser and more uniform 3D network structure than the β-chitin (a → b) NF dispersion. Widths of the β-chitin (a → b) and (b → a) NFs were approximately 8–25 and 3–10 nm, respectively.ArticleINTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES. 91:987-993 (2016)journal articl

Effect of purification method of β-chitin from squid pen on the properties of β-chitin nanofibers

Published online 20 June 2016The relationship between purification methods of β-chitin from squid pen and the physicochemical properties of β-chitin nanofibers (NFs) were investigated. Two types of β-chitin were prepared, with β-chitin (a → b) subjected to acid treatment for decalcification and then base treatment for deproteinization, while β-chitin (b → a) was treated in the opposite order. These β-chitins were disintegrated into NFs using wet pulverization. The β-chitin (b → a) NF dispersion has higher transmittance and viscosity than the β-chitin (a → b) NF dispersion. For the first time, we succeeded in obtaining 3D images of the β-chitin NF dispersion in water by using quick-freeze deep-etch replication with high-angle annular dark field scanning transmission electron microscopy. The β-chitin (b → a) NF dispersion has a denser and more uniform 3D network structure than the β-chitin (a → b) NF dispersion. Widths of the β-chitin (a → b) and (b → a) NFs were approximately 8–25 and 3–10 nm, respectively.ArticleINTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES. 91:987-993 (2016)journal articl

Gel friction: A model based on surface repulsion and adsorption

A model describing the frictional force produced when a polymer gel is sliding on a solid surface has been proposed from the viewpoint of solvated polymer repulsion and adsorption theory at a solid surface. General relations for the frictional force f expressed as functions of the normal loading P, sliding velocity v, the polymer volume fraction Φ, or the elastic modulus E of the gel, etc., have been derived by applying scaling relations to the model. For the repulsive case, f is ascribed to the viscous flow of solvent at the interface and f is theoretically demonstrated to be proportional to the sliding velocity v and the normal pressure P when the pressure is smaller than the elastic modulus of the gel. For the attractive case, in addition to the hydrodynamic friction, the force to detach the adsorbing chain from the substrate appears as friction. When v is not very large, f α v. At an intermediate velocity, f has a velocity dependence less than linear, depending on the strength of adsorption. At a higher sliding velocity, f α v again since the hydrodynamic friction becomes predominant at this stage. The theoretical results coincide well with some experimental observations that confirm the essential feature of the model

Gel machines constructed from chemically cross-linked actins and myosins

We report an ATP fueled soft gel machine reconstructed from muscle proteins of actin and myosin. Chemically cross-linked actin gel filaments, several decade times the length of native actin filaments (F-actin) move along a chemically cross-linked myosin fibrous gel (1 cm long and 50 μm in diameter) with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. The motility observed in muscle protein-gels suggests that one might reconstruct a soft machine fueled by chemical energy by using actin and myosin molecules as elementary elements

Microtubule bundle formation driven by ATP : the effect of concentrations of kinesin, streptavidin and microtubules

Recently, a method was established for the formation of microtubule (MT) assemblies by an active self-organization (AcSO) process, in which MTs were crosslinked during sliding motion on a kinesin-coated surface, and this was coupled with adenosine triphosphate (ATP) hydrolysis. Streptavidin (ST) was the glue used to crosslink biotin-labeled MTs. Although most of the MT assemblies were in the bundle form, they varied in size, shape and motility, depending on the initial conditions used. In this paper, we systematically examined the effects of the concentrations of kinesin, ST and MT on the formation of MT bundles under the initial conditions of the process

Formation of motile assembly of microtubules driven by kinesins

Microtubule (MT) and kinesin are rail and motor proteins that are involved in various moving events of eukaryotic cells in natural systems. In vitro, the sliding motion of microtubules (rail) can be reproduced on a kinesin (motor protein)-coated surface coupled with adenosine triphosphate (ATP) hydrolysis, which is called a "motility assay". Based on this technique, a method was recently established to form MT assemblies by an active self-organization (AcSA) process, in which MTs are crosslinked during a sliding motion on a kinesin-coated surface. Streptavidin (ST) was employed as glue to crosslink biotin-labeled MTs. Various shapes, sizes, and motilities were formed with the AcSA MT assemblies, depending on the initial conditions. In this paper, we briefly review our recent work on the formation of MT assemblies on a kinesin-coated surface

Gel biomachine based on muscle proteins

We have created an ATP-fueled soft gel machine constructed from muscle proteins. Chemically cross-linked gels of the polymer-actin complex of the length several decades times the length of native actin filament (F-actin) move on myosin-coated surface with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. The motility observed in muscle protein-gels suggests that one might construct a soft machine fueled by chemical energy using actin and myosin molecules as elements. We have investigated the growth process of polymer-actin complexes and the correlation between the polarity and the motility of polymer-actin complex gels