Structure and properties of injection‐molded polypropylenes with different molecular weight distribution and tacticity characteristics

Two series of polypropylenes with different molecular weight distribution and tacticity characteristics were injection molded into flexural test specimens by varying cylinder temperature and the effects of the molecular weight distribution and tacticity on the structure and properties of the moldings were studied. Measured propertied were flexural modulus, flexural strength, heat distortion temperature, Izod impact strength, and mold shrinkage and structures studied were crystallinity, the thickness of skin layer, a*‐axis‐oriented component fraction and crystalline orientation functions. The relations between the structures and properties were also studied. It was found that the molecular weight distribution and tacticity characteristics affect the properties mainly through the molecular orientation and crystallinity, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2142–2156, 2002     

Solubility of NiO in Al2O3

Solubility of NiO in Al₂O₃ was determined by electron probe microanalysisy A diffusion couple method was used by coupling an NiO-doped Al₂O₃ polycrystal to a pure single crystal of Al₂O₃. The solubility of NiO in Al₂O₃ in air was 230 wt ppm (157 at. ppm of cations) and 170 wt ppm (116 at. ppm) at 2073 and 1973 K, respectively. The solubility of NiO in Al₂O₃ obtained in this work was compared with our previous work of the solubility of MgO in Al₂o₃.     

Ergonomics solution for crossing collisions based on field assessment of visual environment at urban intersections in Japan

This paper aims to assess quantitatively the actual visual environment of uncontrolled urban downtown intersections in Japan in relation to frequently occurring crossing collisions and to discuss the safety countermeasures for them. In Field Study 1 dealing with direct visibility, our ultra-wide-angle photograph analysis revealed that most of the right/left-ward visible range at 11 intersections were insufficient to check safety, and the quality of direct visibility was closely associated with causing crossing collisions. The countermeasures to reduce a blind area were determined to be a top priority. In Field Study 2 dealing with indirect visibility, more than half of the 25 traffic convex mirrors had marked shortcomings for preventive safety, and ergonomics guidelines ensuring indirect visibility were proposed for installing traffic convex mirrors. Low-cost/low-technology-oriented countermeasures are highly recommended to obtain clear/sufficient images of crucial information satisfying drivers' requirements on traffic convex mirrors in accordance with those ergonomics guidelines was highly recommended. Crossing collisions could be prevented by improvement of poor direct and indirect visibility.     

Research and Development of the Coprecipitation Process for Lanthanum Germanate Oxyapatite

Although lanthanum germanate oxyapatite (La–Ge–O) has shown good potential for use as a solid electrolyte in energy storage applications, its synthesis has been challenging by either solid‐ or solution‐state methods. In this study, a new synthesis of La–Ge–O was developed through a coprecipitation technique, in which a highly concentrated homogeneous aqueous solution of La and Ge was prepared from aqueous ammonium germanate and lanthanum nitrate solutions with the addition of dilute nitric acid. Several precipitates were formed by pH manipulation, including an amorphous material obtained at pH > 3. Compared to the individual precipitation behaviors of the parent compounds, the amorphous precipitate was formed only from the aqueous two‐component mixture, and appeared to contain both metals. This material was transformed into crystalline mixtures upon heating at 1273 K. The crystalline phases were La₂Ge₃O₉ and hexagonal‐type GeO₂ when the precipitate was formed below pH 8, and the La–Ge–O and La₂Ge₂O₇ phases when the precipitate was formed around pH 8. Product formation from the coprecipitate was discussed based on X‐ray diffraction and thermal analyses. The improved availability of La–Ge–O will allow more extensive investigations of its useful properties.     

Loss factors of mirrors for a gravitational wave antenna

Low-loss mirrors fabricated by ion-beam-sputtering machines for possible application in an interferometric gravitational wave antenna were evaluated by use of Nd:YAG laser light (lambda = 1064 nm) with two distinct measurements: a tabletop experiment that used a short cavity with a small beam with a beam waist of approximately 2w(0) = 0.82 mm, and an optical test that used a 20-m prototypical gravitational-wave detector with a large beam with a beam waist of approximately 2w(0) = 4.4 mm. A multilayer coating comprised 29 layers of SiO(2)/Ta(2)O(5) and one protective coating of SiO(2). The best values obtained as a result of these measurements were 16 ppm (parts in 10(6)) and 30 ppm in total loss, respectively. Also, a two-dimensional loss map generated by use of a small beam successfully revealed the existence of a loss structure within the coating surface. These results imply that a high-reflectance multilayer coating has some inhomogeneities and a loss distribution with a typical scale of a few millimeters and that the total measured losses depend on the beam spot size.     

Isolation,identification, and bioassay of chemicals affecting nonpreference carrot-root resistance to carrot-fly larva

Roots of the carrot cultivars Vertou L.D. (resistant) and Long Chantenay (susceptible) were subjected to detailed chemical analysis to identify extracts and compounds influencing larval host-finding (preference/non-preference) behavior and to compare concentrations of these compounds in resistant and susceptible cultivars. Vertou yielded threefold less volatile material in headspace extracts of pureed roots. Extracts of chopped root in methanol, steam, hexane, and chloroform were inactive in behavioral assays. However, ether extracts were active and their hydrocarbon and carbonyl-rich fractions contained potent attractants. The principal constituent of the carbonyl-rich fraction of each cultivar was the carotatoxin complex comprising the neurotoxin falcarinol (carotatoxin), falcarindiol, and falcarindiol monoacetate, the latter compound here reported for the first time from carrot. Falcarinol (50 and 100 g) was active in a behavioral assay, and all three ingredients of the complex were potent electrophysiological stimuli, eliciting maximum single unit responses to source concentrations of 10 ng. Furthermore, the complex was more abundant by about 1000 g/root in Long Chantenay. As this comprised extra amounts of 70, 862, and 110 g of falcarinol, falcarindiol, and falcarindiol monoacetate, respectively, the observed differences seem both behaviorally and physiologically relevant. It is generally accepted that coevolution has transformed the role of many toxins into host-location cues, but this seems a relatively rare example of a neurotoxin (falcarinol) evincing, in decreased concentrations, nonpreference host resistance. This evolved response to a toxin present in large concentrations is contrasted with that totrans-2-nonenal, which paralyses and kills the larva and is present in only trace amounts in the root.     

An electron-microscopic study of Herpetomonase sp. (Leptomonas pessoai)

The fine structure of the promastigotes of Herpetomonas sp. (Leptomonas pessoai) kept in a defined medium at 28 degrees C is described. This portozoon reveals several features in common with other trypanosomatids. A membrane-bounded organelle measuring 0.2 to 0.8 mum in diameter, similar to that described as peroxisome in Crithidia fasciculata, was also observed. A large cavity, located between the nucleus and the kinetoplast and containing vesicles and small particulate material is discussed in this paper.     

Thermal Degradation Under Pulse Operation in Low-Temperature p-Channel Poly-Si Thin-Film Transistors

We analyzed the heat generation of a low-temperature polycrystalline thin-film transistor in pulse operation and proposed a technique for accurately measuring its thermal temperature in high-frequency operation. From this measurement, we were able to calculate the time constants for heating and radiation for the first time. At a low frequency, the temperature difference between when the pulse was on and off was remarkable. As the frequency was increased, the maximum and minimum temperatures approached each other and became equal at a frequency of approximately 1 kHz. We also measured the degradation in pulse operation and discussed the relationship between the thermal temperature and the degradation in the pulse operation