Finite element analysis of fracture statistics of ceramics: Effects of grain size and pore size distributions

A novel numerical simulation method based on finite element analysis (FEA), which can evaluate the fracture probability caused by the characteristics of flaw distribution, is considered an effective tool to facilitate and increase the use of ceramics in components and members. In this study, we propose an FEA methodology to predict the scatter of ceramic strength. Specifically, the data on the microstructure distribution (i.e., relative density, size and aspect ratio of pore, and grain size) are taken as the input values and reflected onto the parameters of a continuum damage model via a fracture mechanical model based on the circumferential circular crack emanating from an oval spherical pore. In addition, we numerically create a Weibull distribution based on multiple FEA results of a three‐point bending test. Its validity is confirmed by a quantitative comparison with the actual test results. The results suggest that the proposed FEA methodology can be applied to the analysis of the fracture probability of ceramics.     

Identification of <Emphasis Type="Italic">Cellulosimicrobium</Emphasis> sp., a poly(3-hydroxybutyrate)-degrading bacterium isolated from washed rind cheese,Pont-l’évêque lait cru

Environmental pollution caused by commodity plastics has become a global issue. As a result, biodegradable plastics have found multiple applications in recent years, particularly in the manufacture of food packaging containers. However, microbes present in fermented foods have been found to degrade biodegradable plastics. In this study, we report, for the first time, a poly(3-hydroxybutyrate) (P(3HB))-degrading bacterium isolated from a type of washed rind cheese, Pont-l'évêque lait cru. The P(3HB)-degrading isolate, designated as PONα, was characterized in detail. The strain was found to be gram-positive and filamentous-shaped; the DNA G+C content was 71.6 mol%, and anteiso-C15:0 was found to be the major fatty acid. The strain grew well in the range of 37–40 °C and formed a large clear zone on P(3HB) medium at 37 °C. The phenotypic properties and phylogenetic inference indicated that strain PONα is closely related to Cellulosimicrobium cellulans. Strain PONα formed a clear zone on P(3HB), LB with P(3HB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and chitin media plates, whereas no clear zone was found on poly(ethylene succinate) (PESu), poly(butylene succinate) (PBSu), poly(ε-caprolactone) (PCL), poly(lactic acid) (PLA), poly(butylene adipate-co-butylene terephthalate) (PBAT), poly(butylene succinate-co-butylene adipate) (PBSA), and olive oil media plates. Relatively higher P(3HB) hydrolytic activity was observed in the culture supernatant under the co-existence of P(3HB) and the cheese, suggesting that a component of the cheese plays an important role in the hydrolytic activity. These results indicate that microbiota in fermented foods such as cheese can degrade biodegradable plastics, thereby reducing their quality. Therefore, because P(3HB) may be degraded by the microbiota present in cheese, these findings may affect the application of P(3HB) in cheese packaging.     

Predictive control method for a redundant robot using a non-parametric predictor

A bio-inspired robot with many degrees of freedom (DOFs) might be beneficial in coping with various situations that occur in a real environment, because its physical structure resembles that of an animal it is modeled after. However, because of its complicated structure, it is difficult to explicitly model the dynamics and to design the control rules. In this study, we propose a predictive control method based on a non-parametric method. Instead of conducting parameter estimation for a certain parametric model, system identification is performed by collecting data. We apply our method to the control of a robot with a complicated structure. Experimental results show that the control of a robot with many DOFs can be achieved by the proposed method.     

Emission from Silica Hybrid Containing RGB Fluorescent Conjugated Polymers

Summary Red, green and blue fluorescent poly(arylene vinylene)s were prepared by Wittig reaction. Polycondensation of tetraethoxysilane (TEOS) was carried out in the presence of a mixed solution of these polymers to give a silica hybrid in which RGB fluorescent polymers were immobilized without phase separation. White light emission was observed from the ternary polymer blend/silica hybrid.     

Catalytic performance and QXAFS analysis of Ni catalysts modified with Pd for oxidative steam reforming of methane

Pd–Ni bimetallic catalysts prepared by co-impregnation and sequential impregnation methods were compared in the catalytic performance in oxidative steam reforming of methane. The sequential impregnation was more effective to the suppression of hot spot formation. According to the structural analysis by in situ quick-scanning X-ray absorption fine structure (QXAFS) during the temperature programmed reduction, the sequential impregnation method gave the bimetallic particles with higher Pd surface composition because of the low possibility of the Pd–Ni bond formation. Higher surface composition of Pd with higher reducibility than Ni is connected to the enhancement of the catalyst reducibility and the suppression of the hot spot formation.     

Effect of reaction temperature on Fe–Al analcime formation

The effects of reaction period, temperature, and iron species on the zeolite framework type were studied in this work. Gismondine (GIS) is usually synthesized by hydrothermal method at 80°C from sodium metasilicate and aluminum nitrate as starting materials preferentially independent of the presence/absence of iron source. However, the present work revealed that pure analcime (ANA) could be formed at temperatures more than 120°C. A large polyhedral ANA crystal with a diameter of 180 μm was obtained even at a comparatively low temperature such as 150°C at a short reaction period of 1 week. The presence of iron source promoted the formation of pure ANA. Infrared spectroscopy, X-ray diffraction, and ICP-OES analysis suggested that the iron component added as a reactant was incorporated into the ANA framework through the isomorphous substitution for Al.     

Analysis of interaction between mechanical force and chemical effect in cleaning phenomenon by probability density functional method

Probability density functional method was used to determine whether interaction between mechanical force and chemical action in cleaning was an additive effect, a synergistic effect, or an offsetting effect. As a soiled sample, iron (III) oxide soiled fabric, Sudan IV soiled fabric, commercially available artificial soiled fabric containing mixed stains, etc. were used and washed with a tergotometer. Mean value μ_rl and standard deviation σ_rl of the cleaning force distribution were calculated by using probability density functional method, and the interaction was judged using Δμ_rl which is the difference between μ_rl obtained under the two conditions. As results, additive effects between the mechanical force and the pH effect were confirmed in the cleaning of iron (III) oxide soiled fabric and commercially available artificially soiled fabric, and an additive effect between the mechanical force and the effect of the surfactant concentration was confirmed in the cleaning of Sudan IV soiled fabric. Therefore, it was presumed that an additive effect is often established between the mechanical action and the chemical action in cleaning, rather than a synergistic effect or an offsetting effect.     

Durability of the adhesive bond between continuous fibre sheet reinforcements and concrete in an outdoor environment

The authors set out to investigate the durability of the bond between carbon fibre (CF) sheet reinforcement and concrete. They conducted an outdoor exposure test in a moderate climate for 14 years and an immersion test for 6 months on CF sheet bonded to concrete, and then evaluated the adhesive bond properties using the pull-off and peel methods.The pull-off strength slightly decreased after 14 years of exposure, but residual values still indicate quite good adhesive properties. The failure modes for both the initial specimens and the specimens after 14 years of exposure consisted of concrete substrate failures in all cases. This result suggests that the slight decrease in pull-off strength does not necessarily indicate a change in the properties of the bond between CF sheet and concrete. On the other hand, results of the peel tests showed different types of failure modes and seemed more discriminant than those of the pull-off method.As regards specimens immersed in water, pull-off results were in few cases consistent with the peel characterizations, showing significant evolutions in the strength and failure mode. But for most specimens, the two methods provided divergent trends. In the end, this study suggested that the peel test could be relevant for evaluating the durability of the bond between CF sheet and concrete, while the representativeness of the pull-off test remains a matter of discussion.