Accelerated weathering-induced degradation of poly(lactic acid) fiber studied by near-infrared (NIR) hyperspectral imaging

Hydrolysis degradation of a set of drawn poly(lactic acid) (PLA) fibers was induced by an accelerated weathering test, radiating ultraviolet (UV) light under a certain temperature and humidity. The fine features of the transient behavior of the PLA fibers were captured by near-infrared (NIR) hyperspectral imaging. The PLA fibers showed a gradual decrease in mechanical property (e.g., tensile strength), indicating hydrolysis degradation. Thus, the detailed analysis of the spectral variation, in turn, offers useful information on the molecular-level degradation behavior of the drawn PLA fibers. The variation of the spectral intensity as well as band position shift of the crystalline band of PLA was analyzed. The spectral intensity of the crystalline band of PLA showed gradual decrease, suggesting the decrease in molecular weight induced by the hydrolysis degradation. In addition, the crystalline band also exhibited a coinciding shift to the lower wavenumber direction with the weathering test, revealing cleavage-induced crystallization of the PLA samples. Consequently, the hydrolysis degradation induced by the weathering test substantially accelerates predominant degradation of the amorphous structure of the PLA and such variation of the molecular structure, in turn, brings less ductility to the PLA fiber.     

Proposal of limit moment equation applicable to planar/non-planar flaw in wall thinned pipes under bending

In this paper, a limit bending moment equation applicable to all types of planar and non-planar flaws in wall-thinned straight pipes under bending was proposed. A system to rationally classify the planar/non-planar flaws in wall-thinned pipes was suggested based on experimental observations focused on the fracture mode. The results demonstrate the importance of distinguishing between axial and circumferential long flaws in wall-thinned pipes.     

Extending image processing strain measurement system to evaluate fracture behavior of wall-thinned pipes

In this paper, an image processing strain measurement system was extended so that fracture behavior of wall-thinned pipes, such as out of plane and large plastic deformation observed in bulging, can be evaluated by the system. Regular grids with nominal size of 10 mm × 10 mm were marked on 100A carbon steel pipes and the images taken with 6 CCD cameras of 15 million pixels were correlated to achieve resolution of 0.3% strain. Strain of the cylinder's outer surface was evaluated by (1) modeling the grids as a cylindrical shell, (2) measuring deformation of the grid on a projected plane, and (3) applying an updated Lagrangian method. The validity of the system was confirmed by applying the proposed system to the burst tests of a wall-thinned cylinder. In addition, the system measured the non-uniform strain distribution that explained the unexpected cracking location.     

Emerging technology and service enhancement for cordless telephonesystems

A brief history of the development of cordless telephone systems in Japan is given. The efficient frequency utilization and upgraded service provided by this technology are discussed. A business cordless system is proposed for extended service areas using a portable telephone facility. The potential extension of this system to a local area portable telephone system is mentioned     

Comparison between Y-doped ceria and Ho-doped ceria: Electrical conduction and microstructures

The electrical conduction and microstructure in Y-doped ceria and Ho-doped ceria were investigated. Visible differences between the two doped ceria were observed. The plots of conductivity of Y-doped ceria are well fit to the Arrhenius behavior, while curvature and kinks were observed on the plots of Ho-doped ceria. Such deviation from the Arrhenius behavior could be related to the existence of precipitates in Ho-doped ceria. It indicates that the electrolytic conductivity of doped ceria could be significantly influenced by microstructure features.     

Power system control method using customers' energy storage systems and the verification of proposed method

Advanced energy storage systems have been widely applied to industries and are being installed at large buildings and factories to realize efficient energy usage. This paper presents a control method involving load frequency control and distribution network control (loss reduction control) using a part of customers' owned battery capacity. When 10% of total battery capacity of 100 MW in a network of 30‐GW generator capacities is used for load frequency control, a total of 1500‐MW generation units for load frequency control, at maximum, can be stopped without deterioration of power quality. In addition, when batteries are used for loss reduction in a distribution network, 2% of the loss on a summer day can be reduced. To realize both effects to their fullest, a novel integrated control algorithm is proposed and its economic effect is evaluated by numerical simulations. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(4): 11–20, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20704     

An energy trading system with consideration of CO2 emissions

Abatement of CO₂ emission is one of the most important issues in the 21st century regarding preservation of the earth environment. This paper addresses a utility operations planning problem for distributed energy management systems (DEMSs), where we are to obtain optimal plans that minimize both costs and CO₂ emissions. A DEMS consists of multiple entities that seek their own economic profits. In this paper, we give a mathematical formulation of the utility operations planning problem for each entity, and propose an energy trading market, which utlizes a multi‐attribute auction protocol in order to deal with both a price and a CO₂ emission rate. Experimental results show that collaboration among entities through the market provides a more profitable plan for each entity and abatement of CO₂ emission is also achieved. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(4): 54–63, 2008; Published online in Wiley InterScience ( www.interscience.wiley. com ). DOI 10.1002/eej.20418     

Influence of γ Irradiation on the Mechanical Strength and In Vitro Biodegradation of Porous Hydroxyapatite/Collagen Composite

Gamma irradiation treatment (GIT) is the most widely used sterilization method for biomaterials in spite of the potential to degrade polymers. The adverse effects of GIT on the mechanical properties and biological stabilities of porous hydroxyapatite/collagen (HAp/Col) composites were investigated in this study. Those properties of a porous HAp/Col composite stabilized by dehydrothermal treatment (DHT) drastically decreased by GIT in the same manner as conventional pure Col materials. DHT after GIT could partially eliminate the adverse effects, due to the introduction of cross-linkage among the degraded Col molecules.     

Detection of enzymatically generated hydrogen peroxide by metal-based fluorescent probe

We developed a metal-based fluorescent probe for H(2)O(2) called MBFh1, which has an iron complex as a reaction site for H(2)O(2) and a 3,7-dihydroxyphenoxazine derivative as the fluorescent reporter unit. The iron complex reacts quickly with H(2)O(2) to form oxidants, and then the oxidants convert the closely appended nonfluorescent 3,7-dihydroxyphenoxazine moiety to resorufin in an intramolecular fashion. The quick response to H(2)O(2) allows us to plot the enzymatic evolution of H(2)O(2). A combination of N-acetyl-3,7-dihydroxyphenoxazine and horseradish peroxidase has been frequently used to detect enzymatically generated H(2)O(2), but this method has interference with phenol derivatives. The use of MBFh1 overcomes this drawback.