Hindered oscillation and e.s.r. spectra of alkyl free radicals trapped in irradiated polyethylene crystals

Structures of alkyl radicals trapped in solution grown crystals of polyethylene and urea-polyethylene complex were studied in detail. A twisted configuration of methylene group with angle of 4.6° from the regular trans-trans configuration was found for the rigid state configuration of the alkyl radical at 77K. Temperature dependences of hyperfine splitting widths due to the β-protons were observed, and analysed in terms of the hindered oscillation of the β-methylene group. The value of the potential barrier height of hindered oscillation was found to be 900 kcal/mol for polyethylene crystal and 600 kcal/mol for urea-polyethylene complex; indicating that the radical site in urea-polyethylene complex is more mobile than that in polyethylene crystal.     

Coordination assemblies from a Pd(II)-cornered square complex

The [enPd(II)]2+ (en = ethylenediamine) unit has emerged as a versatile building block in molecular self-assembly. In particular, the 90 degrees coordination angle of the metal has been judiciously used in the design of new discrete two- and three-dimensional structures. Our last 15 years of work with the Pd(II)-cornered unit is summarized in this Account, from the spontaneous formation of a Pd4 square metal complex to a family of architectures such as cages, bowls, boxes, tubes, catenanes, and spheres.     

Novel IV-Group Based Diluted Magnetic Semiconductor: CrxGe1?x

Cr_xGe_1–x (x 0.08) films were grown on GaAs (001) and Ge (001) substrates using molecular beam epitaxy (MBE) method, and their magnetic and transport properties have been studied in the temperature range between 1.8 and 300 K. All of the films exhibited weak paramagnetic behavior. Transport measurements showed that magnetoresistance ratio and the anomalous Hall resistance depend on the Cr concentration x and the kinds of substrate.     

S-Conart: an interaction method that facilitates concept articulation in shopping online

This study addresses building an interactive system that effectively prompts customers to make their decision while shopping online. It is especially targeted at purchasing as concept articulation where customers initially have a vague concept of what they want and then gradually clarify it in the course of interaction, which has not been covered by traditional online shopping systems. This paper proposes information presentation methods to effectively facilitate customers in their concept articulation process, and the framework for interaction design to enable the methods. Specifically, this study builds a system called S-Conart that facilitates purchasing as concept articulation through support for customers conception with spatial-arrangement style information presentation and for their conviction with scene information presentation, and then makes a set of evaluation experiments with the system to verify that the approach used in building the system is effective in facilitating the purchasing as concept articulation.     

Short nap versus short rest: recuperative effects during VDT work

The effects of a 20-min nap during 2 h of visual display terminal (VDT) work were examined. Ten young healthy adults took a 20-min nap or a 20-min rest I h after VDT work, followed by another 1 h of VDT work. A 20-min rest temporarily restored subjective sleepiness, but it deteriorated during the additional 1 h of work. In contrast, a 20-min nap maintained subjective alertness and performance level at a higher level and mental fatigue at a lower level for the additional 1 h of work. These results suggest that a short nap would be useful to both fatigue recovery and fatigue prevention during continuous VDT work. The present findings may provide a new work/rest strategy.     

Improved test for the migration of antimony and germanium from polyethylene terephthalate

A simple and rapid test has been developed to quantitatively measure the migration of antimony (Sb) and germanium (Ge) from polyethylene terephthalate (PET) products. The PET product was soaked in 4% acetic acid (2 mL/cm2) for 30 min at 60 degrees C and 95 degrees C. The test solution was analyzed by ICP-MS. Recoveries of spiked Sb (0.025 microg/mL) and Ge (0.05 microg/mL) were 101% and 100%, respectively, with relative standard deviations (RSDs) of 2.3% and 1.7%. In ten successive analyses, Sb and Ge in the 4% acetic acid solution were analyzed with RSDs of 1.7% and 2.2%. Sb and Ge were not subject to interference from other elements simultaneously present in the 4% acetic acid solution. This method is simple, rapid and safe, requiring no pretreatment or use of the hazardous solvent carbon tetrachloride. Therefore, this test is a useful method to analyze Sb and Ge migration from PET products.     

Drying ability of anhydrous sodium sulfate on wet organic solvents after liquid-liquid partition

Water concentration in organic solvents after liquid-liquid partition was determined by the Karl Fischer titration method. n-Hexane and petroleum ether showed quite low levels of water, such as 0.1 mg/mL. The water concentration in wet ethyl acetate was about 20-30 mg/mL and that in diethyl ether was about 8-10 mg/mL. Anhydrous sodium sulfate absorbed about 20-25% of the water after vigorous mixing with wet ethyl acetate or diethyl ether. Wet acetonitrile extract from wet food, which contained about 60 mg/mL water after salting out with sodium chloride, was not dried at all with anhyfrous sodium sulfate treatment. Spiking n-hexane into wet ethyl acetate or wet diethyl ether was effective to exclude water. Spiking toluene into salted acetonitrile drove out water and dissolved sodium chloride. It can be concluded that the drying ability of anhydrous sodium sulfate towards wet organic solvents is poor, but it is effective in removing suspended water in solvents.     

Fine SiC fiber synthesized from organosilicon polymers: relationship between spinning temperature and melt viscosity of precursor polymers

A very fine silicon carbide (SiC) fiber with diameter of 6 m, about a half of that of a commercially available SiC fiber, was synthesized from a polymer blend of polycarbosilane (PCS) and polyvinylsilane (PVS). The fine SiC fiber was obtained by optimizing the composition and the spinning temperature of PCS-PVS polymer blends. In order to determine these optimum conditions, the relationship between temperature and melt viscosities of the polymer blends was investigated. As a result, it was found that the optimum spinning temperature range was within a temperature range where the melt viscosity is 5–10 Pa · s. Moreover, by blending PVS with PCS, the spinning temperature of the polymer blends was lowered, the spinnability of polymer system was improved, and finer polymer fiber was obtained compared with PCS. The optimum content of PVS in the polymer blend was 15–20 wt%.     

Offset Cassegrain Earth Station Antenna for the Japanese Domestic Satellite Communication System

Offset reflector antennas have advantages for communication systems because they are not severely subject to blocking. Difficulties mainly arising from structual asymmetries have inhibited the realization of an offset reflector antenna with a large aperture for commercial use. This paper describes the design of an offset Cassegrain earth station antenna for the Japanese domestic satellite communication system. Antenna measurements showed 76 and 69 percent aperture efficiencies at 20 and 30 GHz, respectively, less than -20 dBi wide angle directivity and an 18 K noise temperature in operating conditions. Performances are far superior to conventional axisymmetrical earth station antennas. The antenna was reassembled on a telephone office building after the measurements. The antenna gain was reconfirmed there, using the sun as a radio frequency source. Experiments show that the earth station antenna and a terrestrial antenna can be placed on the same building without serious interference.