Poly(ethylene terephthalate) (PET) texture was exposed to oxygen plasma glow discharge to produce peroxides on its surfaces. These peroxides were then used as catalysts for the polymerization of acrylic acid (AA) in order to prepare a PET introduced by a carboxylic acid group (PET-A). Chitosan and quaternized chitosan (QC) were then coupled with the carboxyl groups on the PET-A to obtain chitosan-grafted PET (PET-A-C) and QC-grafted PET (PET-A-QC), respectively. These surface-modified PETs were characterized by attenuated total reflection Fourier transform IR spectroscopy, electron spectroscopy for chemical analysis, and a contact angle goniometer. The amounts of AA, chitosan, and QC grafted on the PET surfaces as determined by the gravimetric method were about 6, 8, and 9 g/cm 2 , respectively. The antibacterial activity of the surface-modified PET textures was investigated using a shake flask method. After 6 h of shaking, the growth of bacteria was markedly inhibited by PET with ionically (86% in PET-A Ϫ -C ϩ ) and covalently (75% in PET-A-C) grafted chitosan and with covalently grafted QC (83% in PET-A-QC). After the laundering the inhibition of the growth of the bacteria was maintained in the range of 48 -58%, showing the fastness of the chitosan-grafted PET textures against laundering.

Prior to curing, we evaluated thermal stability of poly(butylene succinate) (PBS). Above 170°C, PBS was severely degraded and the degradation could not be successfully stabilized by an antioxidant. PBS was crosslinked effectively by DCP at 150°C, and the gel fraction was increased as DCP content increased. The major structure of crosslinked PBS is supposed to consist of an ester and an aliphatic group. The tensile strength and elongation of PBS were improved with increasing content of DCP, but tear strength was only slightly affected. The higher the crosslinking, the lower the heat of crystallization (⌬H c ) and heat of fusion (⌬H f ). However, the melt crystallization temperature (T c ) of crosslinked PBS was higher than that of PBS. The viscosity of crosslinked PBS increased and exhibited rubbery behavior as the content of curing agent increased. The biodegradability of crosslinked PBS did not seriously deteriorate.

This paper investigates the influence of two types of gait perturbation (i.e., trip and slip) induced by a programmable split-belt treadmill on the body's compensatory responses. Our fall-inducing technology equipped with a commercially available programmable split-belt treadmill provides unpredictable trip and slip perturbations during walking. Two force plates beneath the split-belt treadmill and a motion capture system quantify the body's kinetic and kinematic behaviors, and a wireless surface electromyography (EMG) system evaluates the lower limb muscle activity. Twenty healthy young adults participated. The perturbations (i.e., trip and slip) were applied randomly to the participant's left foot between the 31st and 40th steps. The kinetic and kinematic behaviors and lower limb muscle activity were assessed during the standing, walking, and recovery periods. Compared with trip perturbations, stepping responses to slip perturbations were quicker and trunk, shoulder, and whole body center of mass movements after slip perturbations were higher; the EMG results showed that tibialis anterior, gastrocnemius, rectus femoris, and biceps femoris activities were also higher. The two common types of gait perturbation (i.e., trip and slip) induced by a commercially available programmable split-belt treadmill influenced the body's compensatory responses.

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The mechanical properties and tear resistance of an ecofriendly flexible packaging film, i.e., poly(lactic acid) (PLA)/poly (butylene adipate–co–terephthalate) (PBAT) film, were investigated via a blown film extrusion process. The application of PLA and PBAT in product packaging is limited due to the high brittleness, low stiffness, and incompatibility of the materials. In this study, the effects of various plasticizers, such as adipate, adipic acid, glycerol ester, and adipic acid ester, on the plasticization of PLA and fabrication of the PLA/PBAT blown film were comprehensively evaluated. It was determined that the plasticizer containing ether and ester functionalities (i.e., adipic acid ester) improved the flexibility of PLA as well as its compatibility with PBAT. It was found that the addition of the plasticizer effectively promoted chain mobility of the PLA matrix. Moreover, the interfacial adhesion between the plasticized PLA domain and PBAT matrix was enhanced. The results of the present study demonstrated that the plasticized PLA/PBAT blown film prepared utilizing a blown film extrusion process exhibited improved tear resistance, which increased from 4.63 to 8.67 N/mm in machine direction and from 13.19 to 16.16 N/mm in the transverse direction.

Many stroke survivors have limited ankle range of motion (ROM) caused by weak dorsiflexors and stiff plantarflexors. Passive ankle stretching exercises with physical therapists or a stretching board are usually recommended, but these treatments have some limitations (e.g., cost and availability of physical therapists). In this paper, we assessed the results of ankle stretching exercises delivered by a robotic ankle stretching system called motorized ankle stretcher (MAS) that we developed or by a stretching board on ankle ROM, balance control, and gait performance. The 16 stroke survivors were randomly assigned to an intervention group (IG) or a control group (CG) and participated in seven sessions of dorsiflexion stretching exercises for three-and-a-half consecutive weeks. Laboratory assessments included pre-assessment (baseline at the beginning of the first exercise session), post-assessment (at the end of the seventh exercise session), and retention assessment (one month after the seventh exercise session). All assessments included ankle ROM for the affected side, static/dynamic balance control with a sensory organization test (SOT), walking speed, walking cadence, and step length for the affected and unaffected sides. During seven sessions of ankle stretching exercises, the IG performed them using the MAS, and the CG used a stretching board. The IG significantly improved ankle ROM, SOT scores (i.e., static/dynamic balance control), walking speeds, walking cadences, and step lengths for the unaffected side after completing the seven exercise sessions of ankle stretching exercises and maintained the enhancements at the retention assessment. The CG did not significantly improve across the majority of outcome measures except for the SOT scores between the pre-assessment and retention assessment. Future work will investigate the ideal intensity, frequency, and duration of exercising with the MAS. Our research on technology-assisted ankle rehabilitation, which can ascertain the level of persistent improvement, long-term performance retention, and carry

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