We investigated how the surface coating of leathers influenced 'touch feeling' and 'grip comfort' of leather steering wheels. Four leather sheets coated by different urethane coating materials and four...
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This paper discusses the actuation durability of a conducting shape memory polyurethane (CSMPU) actuator. Introduced in 2004, the CSMPU actuator was manufactured by an in situ polymerization method for shape memory po...
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ISBN:
(纸本)9781605601250
This paper discusses the actuation durability of a conducting shape memory polyurethane (CSMPU) actuator. Introduced in 2004, the CSMPU actuator was manufactured by an in situ polymerization method for shape memory polyurethane with multiwalled carbon nanotubes. In order to apply the CSMPU to smart actuators and determine detailed design concepts, the durability data should be measured. Hence, the experiments in this research were designed to obtain durability data, and the maximum number of actuation cycles versus the initial elongation ratio and the actuation temperature were measured for the purpose of assessing durability. The broken surfaces of the specimens were investigated.
Background: Tripeptidyl-peptidase I, also known as CLN2, is a member of the family of sedolisins (serine-carboxyl peptidases). In humans, defects in expression of this enzyme lead to a fatal neurodegenerative disease,...
Background: Tripeptidyl-peptidase I, also known as CLN2, is a member of the family of sedolisins (serine-carboxyl peptidases). In humans, defects in expression of this enzyme lead to a fatal neurodegenerative disease, classical late-infantile neuronal ceroid lipofuscinosis. Similar enzymes have been found in the genomic sequences of several species, but neither systematic analyses of their distribution nor modeling of their structures have been previously attempted. Results: We have analyzed the presence of orthologs of human CLN2 in the genomic sequences of a number of eukaryotic species. Enzymes with sequences sharing over 80% identity have been found in the genomes of macaque, mouse, rat, dog, and cow. Closely related, although clearly distinct, enzymes are present in fish (fugu and zebra), as well as in frogs (Xenopus tropicalis). A three-dimensional model of human CLN2 was built based mainly on the homology with Pseudomonas sp. 101 sedolisin. Conclusion: CLN2 is very highly conserved and widely distributed among higher organisms and may play an important role in their life cycles. The model presented here indicates a very open and accessible active site that is almost completely conserved among all known CLN2 enzymes. This result is somehow surprising for a tripeptidase where the presence of a more constrained binding pocket was anticipated. This structural model should be useful in the search for the physiological substrates of these enzymes and in the design of more specific inhibitors of CLN2.
The kinetics of water uptake into the dry form of, and benzoic acid diffusion through, swollen inhomogeneous poly(acrylonitrile-acrylamide-acrylic acid) gels were investigated with gravimetry and ultra-violet visible ...
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The kinetics of water uptake into the dry form of, and benzoic acid diffusion through, swollen inhomogeneous poly(acrylonitrile-acrylamide-acrylic acid) gels were investigated with gravimetry and ultra-violet visible spectroscopy, respectively. The goal is to understand the effects of ionizable moieties and water-polymer affinity on the rate of water diffusion during the formation of hydrogels from glassy polymers and on the free-volume mechanism for solute transport through the resulting swollen networks. The xerogel with intermediate acid content or minimal affinity with water has the maximum water diffusion coefficient in the initial swelling stage and the maximum deviation from Fickian transport. The molecular diffusion of benzoic acid through hydrogels was found to be controlled by the swelling, and the size of voids for solute diffusion does not remain constant over all the range of compositions. This discrepancy from the simple free-volume theory is due to a wide range of molecular interactions for gels with amide/acid moieties. In conclusion, dynamic swelling is influenced by water-polymer affinity and subsequently causes various types of steady transport in hydrogels.
An investigation on the influence of chemical compositions and surface properties (e.g., surface free energy in air and hydrogel-water interfacial energy) on the adsorption of bovine serum albumin (BSA) at pH 7.4 on t...
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An investigation on the influence of chemical compositions and surface properties (e.g., surface free energy in air and hydrogel-water interfacial energy) on the adsorption of bovine serum albumin (BSA) at pH 7.4 on to a series of poly(acrylonitrile-acrylamide-acrylic acid) hydrogels was carried out. The interfacial energetics were determined from the contact angle data for air-gel and octane-gel in the water environment and the specific adsorption of BSA was determined with UV-VIS spectroscopy. It is shown that the higher contents of amide and acid groups in hydrogel bulk lead to the greater polar component of surface energy in air and the greater BSA adsorption in aqueous solutions. The BSA adsorption decreases with water amount in gels at lower amide/acid contents and increases at higher contents. The results imply that the interfacial interactions between the protein and the reorganized hydrogel interface in exposure with water, as well as the penetration of protein into pores of swollen gels, influence the BSA adsorption. (C) 1996 John Wiley & Sons, Inc.
Dynamic mechanical properties, low-temperature impact behavior, flexural modulus and heat distortion temperature (HDT) of isotactic polypropylene (i-PP) and propylene-ethylene block copolymer (Co-PP) toughened with st...
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Dynamic mechanical properties, low-temperature impact behavior, flexural modulus and heat distortion temperature (HDT) of isotactic polypropylene (i-PP) and propylene-ethylene block copolymer (Co-PP) toughened with styrene-ethylene butylene-styrene triblock copolymer (SEBS), at blending ratios of 0–30 phr, were studied and compared. A scanning electron microscopic morphology study of the impact-fractured surfaces demonstrated the changes in fracture mechanisms at various temperatures and SEBS contents. SEBS remarkably improves the impact endurance in the lower-temperature range when blended with Co-PP in comparison with i-PP, due to the increased compatibility in the interface between SEBS particles and the Co-PP matrix.
The water uptake and swelling behaviour of physically crosslinked, inhomogeneous poly(acrylonitrile-acrylamide-acrylic acid) hydrogels from 10 to 60 degrees C were determined by gravimetry/differential scanning calori...
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The water uptake and swelling behaviour of physically crosslinked, inhomogeneous poly(acrylonitrile-acrylamide-acrylic acid) hydrogels from 10 to 60 degrees C were determined by gravimetry/differential scanning calorimetry and volume measurement, respectively. The contents of water and its non-bound portion were found to reach a minimum value at acrylamide content around 33.5 mol%, at which the water uptake of this gel does not vary with the temperature. The non-bound water was found to decrease gradually and then increase with increasing amide concentration. The duration of the post-gelation treatment between -10 and 10 degrees C was also shown to be one of the factors affecting the extent of the water uptake in gels. The critical endpoint temperatures (T(c)s) of hydrogels, obtained from volume phase transition data upon changing the acetone concentration in aqueous solutions at various temperatures, were shown to decrease with the increasing acid or amide contents. The water uptake for gels with lower amide contents decreases with increasing temperature. However, there is an opposite trend for water uptake in gels with higher amide content, and the critical points on the plots of the amount of water uptake versus temperature appear at a temperature equal to T-c.
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