Extremely low-noise MESFETs fabricated by metal-organic chemical vapour deposition

Quarter-micron gate low-noise GaAs MESFETs have been developed by delineating gate electrodes by an electron-beam lithography technique and by using high-purity epiwafers prepared by a metal-organic-chemical vapour deposition (MOCVD) technique. At 18 GHz, a noise figure of 1.75 dB with an associated gain of 8.5 dB and a maximum available gain of 11 dB were obtained at drain currents of 10 mA and 30 mA, respectively. This is the lowest noise figure yet reported for low-noise GaAs MESFETs.     

Antinociceptive effect of L-arginine in diabetic mice

The antinociceptive effect of L-arginine in streptozotocin-induced diabetic mice was examined. Although s.c. administration of L-arginine produced a dose-dependent inhibition of the tail-flick response in both non-diabetic and diabetic mice, the antinociceptive response was greater in diabetic mice than in non-diabetic mice. The antinociceptive effects of L-arginine in both diabetic and non-diabetic mice were significantly antagonized by s.c. administration of naltrindole, a selective delta-opioid receptor antagonist. However, neither beta-funaltrexamine, a selective mu-opioid receptor antagonist, nor nor-binaltorphimin ++, a selective kappa-opioid receptor antagonist, significantly affected the antinociceptive effect of L-arginine in diabetic and non-diabetic mice. These results suggest that L-arginine produces a marked antinociceptive effect in diabetic mice through the activation of delta-opioid receptors.     

Novel antiasthmatic agents with dual activities of thromboxane A2 synthetase inhibition and bronchodilation. 1. 2-[2-(1-Imidazolyl)alkyl]-1(2H)-phthalazinones

A number of 4-substituted 2-[omega-(1-imidazolyl)alkyl]-1(2H)-phthalazinones were synthesized in order to develop agents possessing both thromboxane A2 synthetase inhibitory and bronchodilatory activities. The pharmacological evaluation of these compounds disclosed that they have both activities to various extents. Both activities were slightly dependent on the length of the 2-substituents and largely affected by the nature of the 4-substituents. Compounds bearing phenyl and thienyl groups exhibited relatively high and well-rounded activities. Among these compounds, 12j and 15f were found to be the most effective agents having well-rounded activities in vitro and in vivo. Introduction of a carboxyl group reduced both activities contrary to our expectation. 4-(3-Pyridyl)phthalazinone 18b was of particular interest because of unexpectedly high in vivo activities in spite of an absence of significant in vitro activities.     

Heterogeneous point mutations of the p53 gene in pulmonary fibrosis

Lung cancer is a frequent complication in pulmonary fibrosis. Overexpression of p53 proteins has been demonstrated by immunostaining in bronchoepithelial cells in patients with idiopathic pulmonary fibrosis. However, it is still unclear whether this overexpressed p53 protein is wild-type or mutant. It was hypothesized that pulmonary fibrosis may be a precancerous lesion with deoxyribonucleic acid point mutations in bronchoepithelial cells. Mutations of the p53 gene were tested for by fluorescence-based single-strand conformation polymorphism (FSSCP), cloning-sequencing and immunostaining techniques. Out of 10 tissue samples that demonstrated overexpression of p53 protein by immunostaining, nine (90%) exhibited point mutations and eight (80%) exhibited heterogeneous point mutations of the p53 gene. The mutations found in pulmonary fibrosis were scattered throughout the central part of the p53 gene, and both guanine (G):cytosine (C) to adenine (A):thymine (T) and A:T to G:C transitions were frequently observed. In conclusion, frequent heterogeneous point mutations of the p53 gene were detected in pulmonary fibrosis. These mutations may have resulted from several types of deoxyribonucleic acid damage that occurred in bronchoepithelial cells and this may explain previous findings of a very high incidence of lung cancer complicating pulmonary fibrosis.     

Dislocation dynamics theory for fatigue crack growth

Dislocation group dynamics theory is used to deduce a power type expression for fatigue crack growth. In general, the results reflect only a single rate process, and thus one activation energy which is small compared to those in usual rate processes. The frequency dependence for this power function type fatigue crack growth rate was also obtained, and yield reasonable agreement with experimental results from the literature.     

Temperature Effects on Unconfined Compressive Strength and Microstructure of Foamed Mixture Lightweight Soil Containing Flaked Polyethylene Terephthalate (PET)

Lightweight soil technology has been widely used in construction projects to solve soft ground problems. Previous work, however, has shown that the maximum interior temperature of field test bodies reaches to about 90°C. On the other hand, industrial waste disposal is an increasing problem. PET (polyethylene terephthalate) waste is now generated in vast quantities to increased consumption of drinking water sold in PET bottles. Making effective use of PET waste as a ground material may help solve the problem of its disposal. This paper describes the effects of initial high temperature curing on unconfined compressive strength and the microstructure of foamed mixture lightweight soil containing PET flake. Increase in PET-cement ratio lessened the decrease in unconfined compressive strength with increasing initial temperature. This property makes PET flake useful as a construction material. However, unconfined compressive strength decreases with increasing initial temperature at all PET-cement ratios. Observations show that the microstructure of foamed mixture lightweight soil containing PET flake have noticeable cracks if samples are cured at 90°C for 1 day; the PET flake is not completely combined with the matrix. The formation of this microstructure is the main factor of the remarkable strength decrease based on initial high temperature curing.     

Laboratory and Field Evaluations of Recycled Gypsum as a Stabilizer Agent in Embankment Construction

Approximately 1.6 million tons of gypsum waste plasterboard are produced annually in Japan. As such, it is essential to find an alternative way to reduce the quantities of this waste material to avoid environmental problems and the high cost of disposal in landfill. This paper describes a case study focused on the use of recycled gypsum, which is derived from gypsum waste plasterboard, to improve the strength of soft clay soil for embankment construction projects taken in consideration environmental impacts. Four different recycled gypsum contents ranging from 0 to 10% was investigated. Two different types of cements—Portland and Furnace slag type B—with a content ranging from 0 to 3% was used to develop solidification for recycled gypsum and improve environmental properties. For this purpose, a series of unconfined compression tests were conducted to evaluate strength performance of treated clay. While a series of environmental tests were conducted to explore the solubility concentration of fluorine, boron, and hexavalent chromium in the untreated and treated soil specimens. Furthermore, hydrogen sulfide and pH were investigated. Results showed that compressive strength and unit weight of treated clay soil increased with the increase of recycled gypsum content. The strength obtained in the field for treated soil with recycled gypsum was found to be greater than that obtained in the laboratory. The early curing days for soil-gypsum mixture had a significant effect on strength performance compared to the later days. The additives of recycled gypsum for tested soil swiftly increased the strength. This is a vital property for improvement embankment trafficability that helps to reduce the construction time and cost. The use of recycled gypsum within the investigated limits had no adverse effect on pH value and hydrogen sulfide gas was found to be less than the standard permitted limits. As well, the solubility concentrations for fluorine, boron, and hexavalent chromium were found within the permitted standard limits in Japan. The curing time had a significant effect on the reduction the release of harmful substance elements investigated. Furnace cement type B had the potential to improve the mechanical and environmental functions for soil-gypsum mixture. It is recommended that Furnace cement type B be used as a solidification agent for soil treated with recycled gypsum because it has low cost and it is more environmentally friendly than Portland cement.     

On‐Demand Liquid Transportation Using Bioinspired Omniphobic Lubricated Surfaces Based on Self‐Organized Honeycomb and Pincushion Films

In this work, on‐demand control of liquids is realized by using elastic, patterned omniphobic surfaces. This paves the way for novel microfluidics, as well as liquid harvesting, transportation, and manipulation technologies. Inspired by the lubricating properties of pitcher plants, microstructured 1,2‐polybutadiene honeycomb and pincushion films obtained by self‐organization are fluorinated by the ene‐thiol reaction and infused with fluorinated lubricant to obtain omniphobic liquid‐repellent surfaces. Unlike conventional bioinspired omniphobic surfaces, the liquid repellency of the fabricated surface can be programmed by changing the surface microstructures via patterning of the film. Furthermore, the elasticity of the omniphobic film is suitable for controlling the repellency through external stimuli. The method presented here for the fabrication of lubricant‐infused omniphobic microstructured surfaces is also simple, cost‐effective, and can be scaled for large area fabrication.