Aichi Science & Technology Foundation

This study investigated the effects of retort sterilization and oxygen on meat coloration during storage of beef meatballs. Beef meatballs were prepared and retort-sterilized under different oxygen concentrations, and color changes were observed after 12 weeks of storage. In the beef meatballs processed in 21 % oxygen, the center cross-section became remarkably pinked with significantly increased a* value, resembling the undesirable persistent pinking in beef. In addition, the outer cross-section turned brown. The oxidation-reduction potential value of the pink cross-section was significantly lower than that of the brown cross-section, although the pH did not change. In addition, oxygen consumption appeared to occur after retort sterilization of the meatballs, and an assay of thiol group concentration, carboxyl compounds, and iron ion valence indicated the oxidation of salt-soluble proteins in browned meatballs. These findings suggest that the observed pinking phenomenon resulted from alterations in the oxidation-reduction state of the meat during storage.

This study was set to fundamentally investigate the characteristics of austenite reversion occurring in maraging steels additive-manufactured by laser powder bed fusion (L-PBF). The maraging steel samples manufactured under different L-PBF process conditions (laser power P and scan speed v) were subjected to heat treatments at 550 oC for various durations, compared with the results of the austenitized and water-quenched sample with fully martensite structure. The L-PBF manufactured samples exhibited the martensite structure (including localized austenite (γ) phases) containing submicron-sized cellular structures. Enriched alloy elements were detected along the cell boundaries, whereas such cellar structure was not found in the water-quenched sample. The localized alloy elements can be rationalized by the continuous variations in the γ-phase composition in solidification during the L-PBF process. The precipitation of nanoscale intermetallic phases and the following austenitic reversion occurred in all of the experimental samples. The L-PBF manufactured samples exhibited faster kinetics of the precipitation and austenite reversion than the water-quenched sample at elevated temperatures. The kinetics changed depending on the L-PBF process condition. The enriched Ni element (for stabilizing γ phase) localized at cell boundaries would play a role in the nucleation site for the formation of γ phase at 550 oC, resulting in enhanced austenite reversion in the L-PBF manufactured samples. The variation in the reaction kinetics depending on the L-PBF condition would be due to the varied thermal profiles of the manufactured samples by consecutive scanning laser irradiation operated under different P and v values.

A phenomenon that Al-6.0%Zn-0.75%Mg alloy sheets furnace-cooled after solution heat treatment had higher strength than water-quenched sheets under specific aging condition was reported. However, the strengthening mechanism related to furnace-cooling had been not clarified yet. In this research, replication test of the strengthening phenomenon of furnace-cooled sheets and the microstructural change during natural aging and artificial aging at 200°C after furnace-cooling after solution heat treatment was investigated by tensile tests, SAXS measurements, STEM observation and electrical conductivity measurement. The strengthen phenomenon of furnace-cooled sheets was reproduced. In as-furnace-cooled sheets, 2-5 nm clusters which induced lattice strain were observed in LAADF-STEM image apart from atomic number contrast in HAADF-STEM image. The clusters seemed to be generated during furnace cooling. The clusters seemed to cause suppression of reversion and promotion of age hardening in furnace-cooled material.

The optimization of processing parameters is indispensable for the laser powder bed fusion (L-PBF) process. The deposited energy density (DED) is one of the process indexes for the L-PBF process and has a simplified formula of P·v−0.5, where P is the laser power, and v is the scan speed. This parameter describes the change in the relative density and the melt pool morphology with laser power and scan speed well, whereas it does not include the effect of other processing parameters, e.g., hatch spacing (S). In the present study, an attempt was made to incorporate the effect of S into DED. Al–12Si (mass%) alloy cube samples were fabricated by L-PBF under various P, v, and S, for evaluating the relative density and the melt pool morphology. The melt pool depth and width of L-PBF-manufactured Al–12Si alloy increased linearly with P·v−0.5 and did not exhibit a clear correlation with S. Based on the experimental observation, the effect of hatch spacing on DED was estimated to be S−0.5, and a new index of P·v−0.5·S−0.5 was proposed. This index described the change in the relative density of the L-PBF-manufactured Al–12Si alloy with laser conditions (P, v, and S) well when the thermal conduction mode melting was dominant. This study also indicated the limitation of the applicability of P·v−0.5·S−0.5 under the keyhole or transition mode melting.

最近, 味噌の製造工程で発酵・熟成工程に使用される容器は, 従来の木製の桶から繊維強化プラスチック (FRP) や金属製のタンクに代わってきている. そのため, 仕込み容器の違いが味噌に与える影響を明らかにすることを目的に, 木桶およびFRP製の仕込み容器で同一原材料と原料処理および配合条件で仕込み, 製造された米味噌を用いて解析を行った. その結果, 木桶味噌とFRP味噌との差異は, 栄養成分, 有機酸および遊離アミノ酸量において若干認められたが, 味覚に関しては大きな影響を与えないことが示された. しかしながら, 香気成分では両者に大きな差が認められ, 木桶で製造された味噌の方が香気成分含量および種類ともに多かった. この要因として, 木桶味噌とFRP味噌の菌叢分布差異が影響していると示唆された.

In situ synchrotron wide-angle X-ray diffraction measurements have been performed successfully for the oriented poly(vinylidene fluoride) β form under the periodically changed high electric field. (i) The β form existing under the low electric field (βlow-E) was found to transform to the βhigh-E phase when subjected to an electric field higher than ca. ± 150 MV/m, as known from the remarkable X-ray diffraction profile change between two phases. In addition, (ii) the inversion of the polar b-axis (or the CF2CH2 dipoles) and (iii) the titling of the zigzag-chain stems were found to occur simultaneously, as already reported in our previous paper (Macromolecules 2021, 54, 2334). These three kinds of phenomena (i–iii) have been found to occur systematically in a cooperative manner. Once the βhigh-E phase was created in the highest electric field strength, it was reserved in the process of decreasing the electric field strength to 0 MV/m, during which, however, the stepwise rotation of the polar b-axis and the chain tilting from the oriented direction occurred again. Once when the electric field strength reached ca. −100 MV/m after passing through 0 MV/m, in addition to the cooperative phenomena of the stepwise b-axial rotation and c-axial tilting, the partial transition from the βhigh-E to βlow-E phases occurred, and then, the βhigh-E phase was stabilized again at −300 MV/m. In the recovery process from −300 to 0 MV/m, the βhigh-E phase was reserved but the b-axial rotation and c-axial tilting still occurred as before. The stepwise b-axial rotation and the cooperative c-axial tilting are speculated to occur through the generation and propagation of TG-kink defects along the chain axis (T: trans and G: gauche C–C torsions), as reported in the previous paper. The quantitative analysis of the observed X-ray diffraction data, in combination with the lattice energy optimization calculations, has allowed us to derive the crystal structure of the βhigh-E phase in addition to the structure of the well-known βlow-E phase. The zigzag chains are packed in parallel along the b-axis similar to the βlow-E phase. However, the unit cell is deformed slightly from the original rectangular shape of the βlow-E phase to the monoclinic type. On the basis of the thus-collected experimental information, the images of the structural changes occurring under the electric field have been derived concretely.

To reveal the origin of coloration in Kasama celadon glazes, the valencies and local coordination structures of Fe in the celadon glaze specimens were evaluated by X-ray absorption fine structure measurements. Specimens were fabricated by a heating-cooling process [oxidation-oxidation (OFOF), reduction–oxidation (RFOF), or reduction-reduction (RFRF)], and exhibited two colors (yellow: OFOF specimens, light blue: RFOF and RFRF specimens). Pre-edge features of their X-ray absorption near edge structure spectra were measured to investigate the valency and local coordination structures of Fe in each specimen. The yellow and light-blue colors originated from FeO4 tetrahedra with Fe in the +3 and +2 oxidation states, respectively.