Effect of stress ratio on fatigue lifetime and crack growth behavior of WC–Co cemented carbide

Two types of fatigue tests, a rotating bending fatigue test and a three- or four-point bending fatigue test, were carried out on a fine grained WC–Co cemented carbide to evaluate its fatigue crack growth behavior and fatigue lifetime. From successive observations of the specimen surface during the fatigue process, it was revealed that most of the fatigue lifetime of the tested WC–Co cemented carbide was occupied with crack growth cycles. Using the basic equation of fracture mechanics, the relationship between the fatigue crack growth rate (da/dN) and the maximum stress intensity factor (K_max) was derived. From this relation, both the values of the threshold intensity factor (K_th) and the fatigue fracture toughness (K_fc) of the material were determined. The fatigue lifetime of the WC–Co cemented carbide was estimated by analysis based on the modified linear elastic fracture mechanics approach. Good agreement between the estimated and experimental fatigue lifetimes was confirmed.     

The effect of Cr2O3 additive on the electrical properties of ZnO varistor

The effect of Cr2O3 additive on the leakage conduction and threshold voltage characteristics of bismuth-based ZnO ceramic varistor was studied. The leakage conduction in the voltage range below the threshold voltage increased with increasing Cr2O3 concentration and is attributed to the Schottky barrier height. It was found that the increases in the apparent threshold voltage were associated with the lowered donor concentration in the depletion region of the ZnO grain. These results were obtained by measuring C–V characteristics, the breakdown voltage at the current density of 10-3 A cm-2 and the microstructure of ZnO ceramics. This revised version was published online in November 2006 with corrections to the Cover Date.     

KINETICS OF LYCOPENE DEGRADATION IN TOMATO PUREE BY HEAT AND LIGHT IRRADIATION

Lycopene as a natural antioxidant may provide protection against a broad range of epithelial cancers. Tomatoes and tomato‐based food products are a major source of lycopene compounds. Thermal processing is the main procedure in tomato puree production. Heat and light induces lycopene oxidation and isomerization of the all‐trans form to the cis form. The level of cis‐isomers increases as treatment time increases but only for a short period during the beginning of the treatment. The major effect of thermal processing was a significant decrease in the total lycopene content. Lycopene is relatively stable if heated at temperatures below 100C, but the duration of heating must be taken into consideration. The kinetics of lycopene degradation was analyzed. A shorter period of time of heating and less light irradiation in processing and storage would reduce lycopene degradation to a great extent.     

Composition of Fermented Grape Juice Continuously Produced by Immobilized Lactobacillus casei

Continuous fermentation of grape juice was carried out in a packed bed column system using Lactobacillus casei adsorbed onto ceramic beads. Chemical components in the reaction vessel of this system were compared with those of a free-cell fermentation. No major differences were noted in the principal components. Diacetyl and methionine levels decreased, however, whereas aspartic acid and cysteine increased. Silica levels increased immediately after initiation of the immobilized cell culture due to elution from the ceramic carrier beads. In two of the five trials the reactor was contaminated with Bacillus megaterium.     

Electrical and Magnetic Properties of Iron-Nickel Sulfide Ceramics

Solid solutions of (Fe,Ni)S were prepared by the metal oxide-carbon disulfide reaction sintering method. These ceramics have the hexagonal NiAs structure, and their lattice parameters depend on the Fe-Ni ratio. The magnetization of these ceramics reduces with decreasing Fe content between 100/0 (Fe/Ni) and 50/50, increases between 50/50 and 40/60, and decreases again between 40/60 and 0/100. The electrical resistivity reduces uniformly with decreasing Fe content of the ceramics.     

Formation of N-Nitrosopyrrolidine in Fried Bacon: Model System Studies

The kinetics of reactions such as the nitrosation of proline or pyrrolidine and the decarboxylation of proline or N-nitrosoproline in heated model systems simulating the pan-frying conditions of bacon were determined. The rate constants, half-life values and activation energy values of these reactions were calculated. The nitrosation of proline or pyrrolidine in adipose model systems occurs readily in the temperature range 80–160°C, while the decarboxylation of proline or N-nitrosoproline proceeds only at 100°C or above. The rates of the above reactions are such that nitrosation of proline > nitrosation of pyrrolidine > decarboxylation of proline or N-nitrosoproline. Results lend credence to the pathway involving N-nitrosoproline in the formation of N-nitrosopyrrolidine in bacon.     

Experimental Services of Energy Management for Energy Users in Business Region on Miyakojima City All‐Islands EMS Demonstration Project

Smart grid and demand response (DR) had been attracting attention and evaluated in several demonstration projects. Many DR experimental results for residential and large‐scale buildings had been evaluated, while evaluation for small size buildings seems to be not enough. In this paper, a new energy service combined EMS method is proposed for small size buildings. Then results of its application to Miyako Island All‐Islands EMS Demonstration Project are introduced. The experimental services include not only DRs but also peak cutting recommendations and energy analysis reports. The results show combination of services can realize more effects than individual service. Especially the peak cutting recommendations and energy analysis reports help energy consumers to learn and understand how to save and manage energy usages that lead to effective DR potentials. Also the experimental system developed for energy data measurement and DR management as an island community EMS is intrduced.     

APPLICATION OF ORGANIC SULFUR COMPOUNDS FOR PETROLEUM REFINING PROCESSES

The effects of sulfur compound PTMP and metal naphthenates on the conversion of the atmospheric residue to light oil and on the coke formation were investigated by carrying out thermal decomposition in a tubular type reactor. When 100μg/g of PTMP was added to residue, gas oil yield increased, but the effect was not significant. However, the coke deposition in the reactor was reduced by the addition of PTMP, When 100μg/g of ferric naphthenate was added, the significant effect was observed on the gas oil increase. However, the coke deposition was enhanced with the increase of gas oil yield by the addition of ferric naphthenate. Both of the increase in gas oil yield and the reduction of coke formation were observed when PTMP (1000μg/g) and ferric naphthenate (100μg/g) were simultaneously used. By the addition of the organic sulfur compound, the formation of the coke produced by the recombination of hydrocarbon redicals yielded by thermal decomposition was suppressed. The advantage of this method is that the construction of new equipment is not required and it enables the increase in the light oil fraction of residual oil by using the existing units.