Ductile‐to‐brittle transition behavior of low molecular weight polycarbonate under carbon dioxide

We investigated the stress–strain behavior of low molecular weight polycarbonate for optical disc grade (OD‐PC) under carbon dioxide (CO₂) at various pressures, and compared the results with that under ambient pressure at various temperatures. Elongation at break decreased sharply with increased CO₂ pressure at around 2 MPa, while the elastic modulus decreased gradually up to 6 MPa. These results indicate that the tensile property changed from ductile to brittle with increased CO₂ pressure, although the molecular motion is accelerated due to the plasticization effect of CO₂. Such ductile‐to‐brittle transition is similar to that observed under elevated temperatures caused by chain disentanglement due to accelerated molecular motion. Although the changes of tensile properties were similar, the craze structure obtained by the brittle behavior was different, i.e., a filamented‐craze structure was obtained under high‐pressure CO₂, while a lace‐like one was obtained under elevated temperatures. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers     

Production of extracellular bifidogenic growth stimulator by anaerobic and aerobic cultivations of several propionibacterial strains

Production of a bifidogenic growth stimulator (BGS) by propionic acid bacteria was investigated under anaerobic and aerobic culture conditions. To measure the concentration of extracellular BGS produced by propionic acid bacteria, we evaluated the effects of bioassay conditions using Bifidobacterium longum as a test microorganism on the formation of a growth-stimulation zone. The diameter of the growth-stimulation zone was significantly affected by both the component concentrations and the pH of a bioassay medium. The optimum component concentrations and pH of a bioassay medium were one-half of the normal values and 8.5, respectively. Using the bioassay method, we can measure the concentration of BGS produced by propionic acid bacteria ranging in concentrations from 0.1 microg/l to 1 mg/l using 1,4-dihydroxy-2-naphthoic acid (DHNA) and 2-amino-3-carboxy-1,4-naphthoquinone (ACNQ) as standards. Of six dairy propionic acid bacterial strains tested, the four strains (Propionibacterium freudenreichii ET-3, P. shermanii PZ-3, P. acidipropionici JCM 6432, and P. jensenii JCM 6433) produced BGS at a concentration range of 4-23 mg/l under the anaerobic culture conditions. Analysis of high performance liquid chromatography (HPLC) showed that more than 70% of total BGS produced in supernatant samples was DHNA and no ACNQ was produced by the strains. The effect of oxygen supply on BGS production was investigated for the four BGS-producing strains. The aerobic conditions exerted in positive effects on BGS production by only P. acidipropionici JCM 6432. The concentration of BGS obtained in the aerobic cultivation of P. acidipropionici JCM 6432 was 1.3-fold than that in anaerobic cultivation. Different properties (BGS production as well as cell growth and glucose metabolism) occurring in response to the aerobic conditions were observed, depending on the propionic acid bacterial strain used. This paper is the first report on BGS production by propionibacterial strains except for P. freudenreichii.     

Dynamic control of the Q factor in a photonic crystal nanocavity

High-quality (Q) factor photonic-crystal nanocavities are currently the focus of much interest because they can strongly confine photons in a tiny space. Nanocavities with ultrahigh Q factors of up to 2,000,000 and modal volumes of a cubic wavelength have been realized. If the Q factor could be dynamically controlled within the lifetime of a photon, significant advances would be expected in areas of physics and engineering such as the slowing and/or stopping of light and quantum-information processing. For these applications, the transfer, storage and exchange of photons in nanocavity systems on such a timescale are highly desirable. Here, we present the first demonstration of dynamic control of the Q factor, by constructing a system composed of a nanocavity, a waveguide with nonlinear optical response and a photonic-crystal hetero-interface mirror. The Q factor of the nanocavity was successfully changed from approximately 3,000 to approximately 12,000 within picoseconds.     

Scalable 10 Gbit/s 4×20.25 μm CMOS/SIMOX ATM switch LSIcircuit based on distributed contention control

A scalable 10 Gbit/s 4×2 ATM switch LSI circuit has been fabricated. It employs a new distributed contention control technique that makes the LSI circuit expandable. To increase the LSI circuit throughput, 0.2 μm CMOS/SIMOX (separation by implanted oxygen) technology is used. It allows the LSI circuit to offer 221 I/O pins, an operating speed of 1.25 Gbit/s and 7 W power consumption     

A 10-Gb/s (1.25 Gb/s×8)4×2 0.25-μm CMOS/SIMOX ATMswitch based on scalable distributed arbitration

This paper presents the design and implementation of a scalable asynchronous transfer mode switch. We fabricated a 10-Gb/s 4×2 switch large-scale integration (LSI) that uses a new distributed contention control technique that allows the switch LSI to be expanded. The developed contention control is executed in a distributed manner at each switch LSI, and the contention control time does not depend on the number of connected switch LSI's. To increase the LSI throughput and reduce the power consumption, we used 0.25-μm CMOS/SIMOX (separation by implanted oxygen) technology, which enables us to make 221 pseudo-emitter-coupled-logic I/O pins with 1.25-Gb/s throughput. In addition, power consumption of 7 W is achieved by operating the CMOS/SIMOX gates at -2.0 V. This consumption is 36% less than that of bulk CMOS gates (11 W) at the same speed at -2.5 V. Using these switch LSI's, an 8×8 switching multichip module with 80-Gb/s throughput was fabricated with a compact size     

Curing of epoxy resin by ultrafine silica modified by grafting of hyperbranched polyamidoamine using dendrimer synthesis methodology

Hyperbranched polyamidoamine–grafted silica was prepared according to dendrimer synthesis methodology. The modified silica was dispersed uniformly in epoxy resin, and the curing of epoxy resin proceeded successfully by heating in the presence of the modified silica; the gel fraction of the epoxy resin cured by the hyperbranched polyamidoamine–grafted silica (grafting = 80.2%) reached 77% at 170°C after 48 h. The gel fraction increased with increasing terminal amino group content of the hyperbranched polyamidoamine–grafted silica. In addition, the curing ability of the silica increased by complexation of the terminal amino groups of the grafted polyamidoamine with boron trifluoride. The modulus of elasticity of the curing materials obtained using the modified silica as a curing agent was lower than that using conventional a curing agent such as ethylenediamine in the presence of untreated silica. On the other hand, the heat resistance of the curing product using the modified silica was superior to that using ethylenediamine, but no difference in glass‐transition temperature was observed. It is expected that hyperbranched polyamidoamine grafted‐silica is incorporated uniformly with chemical bonds in the matrix of the epoxy resin. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 573–579, 2001     

Robot vision robust to changes of lighting conditions using a wide-dynamic-range visual sensor

We have developed a robust vision system for 2D positioning of industrial parts stable to changes of lighting conditions. A wide dynamic range vision sensor that we had developed previously was used to avoid the saturation of object images. Additionally, a gray scale pattern matching technique was employed for robust image processing. Performance of the system with a wide dynamic range vision sensor was investigated experimentally in comparison with that of a system with a conventional video camera. The probability of correct positioning of an object under changing lighting conditions, simulating those in a factory, was 100% for the wide dynamic range vision sensor and 83% for the conventional video camera. The experimental results confirm the effectiveness of the developed system, revealing that dynamic range expansion of the video cameras is very effective for realizing robust robot vision systems. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(2): 34–40, 1997     

Dietary intake of dioxins in Japan in 2016 with time trends since 1998

Total diet samples collected from seven regions throughout Japan in 2016 were analysed for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and dioxin-like polychlorinated biphenyls (DL-PCBs), known collectively as dioxins. This led to estimates of the latest dietary intake of these contaminants for the general Japanese population (≥1 year old). The average daily intake of dioxins for a person weighing 50 kg, calculated at non-detected congener concentrations assumed to be equal to zero, was estimated to be 0.54 pg TEQ (toxic equivalents) kg^?1 body weight (bw) day^?1. This value is well below the tolerable daily intake of 4 pg TEQ kg^?1 bw day^?1 for dioxins in Japan. The average intake was highest from fish and shellfish, followed by meat and eggs. The TEQ contribution of the fish and shellfish group to the total dietary TEQs was significant (89%). The DL-PCBs accounted for about 67% of the dioxin intake. The latest dioxin intake level was compared with previous estimates from total diet study results obtained annually since 1998 to determine the time trends in the dietary intake of dioxins in Japan. Overall, the average dioxin intake appeared to be decreasing gradually during the period of study. The previous average intakes of dioxins ranged from 0.58 to 1.9 pg TEQ kg^?1 bw day^?1. The latest average intake was the lowest since 1998 and was about one-third of the average intake in 1998. This decreasing trend in the dietary intake of dioxins was mainly influenced by the decreased dioxin intakes from two food groups, fish and shellfish, and meat and eggs.