• Asian-Australasian Journal of Animal Sciences
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• v.32 no.8
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• pp.1172-1185
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• 2019

Objective: Meat quality attributes in postmortem muscle tissues depend on skeletal muscle metabolites. The objective of this study was to determine the key metabolic compounds and pathways that are associated with postmortem aging and beef quality in Japanese Black cattle (JB; a Japanese Wagyu breed with highly marbled beef). Methods: Lean portions of Longissimus thoracis (LT: loin) muscle in 3 JB steers were collected at 0, 1, and 14 days after slaughter. The metabolomic profiles of the samples were analyzed by capillary electrophoresis time-of-flight mass spectrometry, followed by statistical and multivariate analyses with bioinformatics resources. Results: Among the total 171 annotated compounds, the contents of gluconic acid, gluconolactone, spermidine, and the nutritionally vital substances (choline, thiamine, and nicotinamide) were elevated through the course of postmortem aging. The contents of glycolytic compounds increased along with the generation of lactic acid as the beef aging progressed. Moreover, the contents of several dipeptides and 16 amino acids, including glutamate and aromatic and branched-chain amino acids, were elevated over time, suggesting postmortem protein degradation in the muscle. Adenosine triphosphate degradation also progressed, resulting in the generation of inosine, xanthine, and hypoxanthine via the temporal increase in inosine 5'-monophosphate. Cysteine-glutathione disulfide, thiamine, and choline increased over time during the postmortem muscle aging. In the Kyoto encyclopedia of genes and genomes database, a bioinformatics resource, the postmortem metabolomic changes in LT muscle were characterized as pathways mainly related to protein digestion, glycolysis, citric acid cycle, pyruvate metabolism, pentose phosphate metabolism, nicotinamide metabolism, glycerophospholipid metabolism, purine metabolism, and glutathione metabolism. Conclusion: The compounds accumulating in aged beef were shown to be nutritionally vital substances and flavor components, as well as potential useful biomarkers of aging. The present metabolomic data during postmortem aging contribute to further understanding of the beef quality of JB and other breeds.

• Transactions of Materials Processing
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• v.31 no.3
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• pp.160-166
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• 2022

The purpose of this study is to investigate the effects of combined addition of Ca and Y on the precipitation and age-hardening behavior of an extruded AZ91 alloy by conducting the aging treatment at 200 ℃ for hot-extruded AZ91 and AZ91-0.3Ca-0.2Y alloys. In the AZ91 alloy, many Mg₁₇Al₁₂ discontinuous precipitate (DP) bands formed during air cooling immediately after extrusion are present, whereas in the AZ91-0.3Ca-0.2Y alloy, a few DP bands and numerous Al₂Y, Al₈Mn₄Y, and Al₂Ca phase particles are distributed along the extrusion direction. The peak-aging time of the AZ91-0.3Ca-0.2Y alloy is 16 hours, twice that of the AZ91 alloy. Although both alloys have similar hardness before aging treatment, the hardness after peak-aging treatment (i.e., peak hardness) of the AZ91-0.3Ca-0.2Y alloy is higher than that of the AZ91 alloy, as 93.1 and 88.7 Hv, respectively. The microstructures of both peak-aged alloys comprise DPs and continuous precipitates (CPs). However, the peak-aged AZ91-0.3Ca-0.2Y alloy has a smaller amount of DPs and a larger amount of CPs than the peak-aged AZ91 alloy. Additionally, the inter-particle spacings of DPs and CPs in the former are significantly narrower than those in the latter. These results demonstrate that the addition of small amounts of Ca and Y to a commercial AZ91 alloy considerably affects the formation rate, size, and amount of CPs and DPs during aging and resultant age-hardening behavior.

• Transactions of Materials Processing
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• v.32 no.4
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• pp.173-179
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• 2023

In this study, the age-hardening behavior and tensile properties of a cast AZ91-0.3Ca-0.2Y (SEN9) alloy are investigated and compared with those of a commercial AZ91 alloy. Even after homogenization heat treatment, the SEN9 alloy contains numerous undissolved secondary phases, Al₈Mn₄Y, Al₂Y, and Al₂Ca, which results in a higher hardness value than the homogenized AZ91 alloy. Under aging condition at 200 ℃, both the AZ91 and SEN9 alloys exhibit the same peak-aging time of 8 h, but the peak hardness of the latter (86.8 Hv) is higher than that of the former (83.9 Hv). The precipitation behavior of Mg₁₇Al₁₂ phase during aging significantly differs in the two alloys. In the AZ91 alloy, the area fraction of Mg₁₇Al₁₂ discontinuous precipitates (DPs) increases up to ~50% as the aging time increases. In contrast, in the SEN9 alloy, the formation and growth of DPs during aging are substantially suppressed by the Ca- or Y-containing particles, which leads to the formation of only a small amount of DPs with an area fraction of ~4% after peak aging. Moreover, the size and interparticle spacing of Mg₁₇Al₁₂ precipitates of the peak-aged SEN9 alloy are smaller than those of the peak-aged AZ91 alloy. The homogenized AZ91 alloy exhibits a higher tensile strength than the homogenized SEN9 alloy due to the finer grains of the former. However, the peak-aged SEN9 alloy has a higher tensile elongation than the peak-aged AZ91 alloy due to the smaller amount of brittle DPs in the former.

• Korean Journal of Agricultural Science
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• v.43 no.1
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• pp.61-71
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• 2016

The effect of postmortem aging on the quality of Semimembranosus muscle (SM) from Hanwoo was investigated. The quality of SM was compared with that of Longissimus dorsi muscle (LD). SM contained higher moisture, protein, and ash, and lower fat than LD (p<0.05). The $a^*$ and $b^*$ values of SM were significantly decreased after 21 days of aging. SM showed higher $a^*$ values than LD at 1 and 7 day of aging (p<0.05). The cooking loss of SM was not affect by aging. SM had higher cooking loss than that of LD throughout the aging period. Although the shear force of SM was significantly decreased by aging, SM showed high shear force compared to LD during aging period (p<0.05). Aging increased lipid oxidation in both muscles (p<0.05). However, TBARS value of SM was significantly lower than that of LD throughout the aging period (p<0.05). There was no effect of aging on the betaine and L-carnitine contents of SM. SM contained higher betaine and L-carnitine than LD in all aging days (p<0.05). Therefore, we concluded that consumer acceptability of SM could be increased by aging based on the increase of tenderness in addition to its high nutritional properties.

• Journal of the Korean institute of surface engineering
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• v.46 no.6
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• pp.235-241
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• 2013

In this study, the effects of alloying elements and thermal aging on the contact resistance of electroplated gold alloy layers were investigated by surface analysis using X-ray photoelectron spectroscopy (XPS). The contact resistance of Au-Ag alloy was lower than that of Au-Ni or Au-Co alloy after thermal aging. The XPS results show that nickel and oxygen present as nickel oxides such as NiO and $Ni_2O_3$ on the surface of gold layers after thermal aging. The increase in the contact resistance after thermal aging is attributable to the nickel oxide layer formed on the surface of the gold layers. The content of nickel diffused from the underlayer during the thermal aging was high in the order of Au-Co, Au-Ni and Au-Ag alloy because the area of grain boundary was large in the order of Au-Ag, Au-Ni and Au-Co alloy.

• Culinary science and hospitality research
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• v.3
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• pp.239-257
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• 1997

This study investigated the effect of the addition of alcohol on the quality change of Chungkukjang during the aging, The Cung-kuk-jang was made by the degree of 3, 5, 10%, respectively, and determined NH2-N, NH3-N, total acidity, cell numbers, lactate, succinate and phenolic acid to measure the change of flavor component in the aging of 2$0^{\circ}C$. 1. In the treatment groups of different amount of alcohol and salt added and aging period of Chung-kuk-hang, NH2-N was more decreased with more addition of alcohol and salt in the 3-and 10-day of aging. NH3-N was increased gradually in the addition of up to 2.0% alcohol and then decreased in the 3-and 10-day of aging. 2. In the treatment groups of different amount of alcohol added and aging period Chung-kuk-hang, the total acidity was more decreased with more addition of alcohol and higher degree of salt. Cell number was decreased rapidly with the addition of 1.0% alcohol in the 3-day and then decreased relatively and in the 10-day of aging, and it was increased with the addition of alcohol 3. With the addition of alcohol and the different growing temperature, the content of phenolic acid was more browning changed at 3$0^{\circ}C$ than that of at 2$0^{\circ}C$ and the phenol content of each group was decreased with increasing the addition amount of alcohol. Thus, the more addition of alcohol amount would the more extend the period of Chung-kuk-hang aging.

• Journal of the Korean Geographical Society
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• v.48 no.3
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• pp.402-416
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• 2013

This paper investigates both the changing spatial patterns of aging population during 1985 to 2010 and their interrelationship with the residential features of elderly households in 2010. The aging level of a region is classified into three different ones such as aging region (7~14%), aged region (14~20%) and super-aged region (over 20%). Residential features of elderly households are examined by such variables as housing type, housing ownership, and house age. Aging process has started from peripheral regions distanced away from Seoul. There are strong tendency that aging households reside in single unit house owned by oneself over 20 years-old aged houses, which shows more strong patterns toward peripheral regions in SMR.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.469-472
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• 2004

There have been numerous accelerated aging laboratory tests for evaluating suitability of polymeric materials and devices. Aging test for materials and its full scale device has been conducted, but poor correlation of aging test such as service experience were observed. Service experience plays a key role in the utility section of composite insulators. A meaningful and reliable accelerated aging test is needed for evaluating composite insulator. During the service these insulators are subjected to aging stress such as humidity, pollution, and electrical field, and erosion and tracking of the weathershed occurs. This paper presents the criteria of reliability evaluation and evaluation facilities for 22.9 kV suspension composite insulator. We adopt the criteria of reliability evaluation consist of two test methods. One is CEA tracking wheel test for examining the tracking and erosion performance of composite insulator. The other is multi-stress aging test for examining effects of environmental factors such as UV, temperature, humidity, etc on composite insulator.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.48-53
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• 2024

We predicted the calendar aging and long-term lifetime of lithium-ion batteries using an electrochemical-based SEI growth model. Numerical simulation was carried out employing the four different long-term SEI growth models (i.e., solvent diffusion limited model, electron migration limited model, Li-interstitial diffusion limited model, reaction limited model), and we calculated the capacity fade and loss of lithium inventory during calendar aging. The result showed that the electron migration limited model and Li-interstitial diffusion limited model showed lower capacity fade, while the solvent diffusion limited model and reaction limited model reached 80% of capacity fade within 10 years. During calendar aging, the lower storage temperature showed less capacity fade due to the hindrance of SEI growth rate. During cycling, the higher C-rate showed a shorter life cycle; however, the differences were not significant.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.167-172
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• 2002

During the operation of military aircraft, maintenance is divided into organizational, intermediate and depot maintenance. In the depot maintenance, after removal of major parts and removable doors, damage assessment is performed. Locating damage, charactering the damage and determining its extent, zoning the damage on the part being repaired and re-evaluation of the damaged area after damage removal. Repair joints are classified by bonded joints and bolted joints, depending on joining material. In this paper, repair method in aging aircraft is investigated and the possibility of application of copmposite patch is surveyed.