THE COLOR STABILITY OF AESTHETIC RESTORATIVE MATERIALS RESULTING FROM ACCELERATED AGING

Lee, Jeong-Seon,Suh, Kyu-Won,Ryu, Jae-Jun The Korean Academy of Prosthodonitics 2008 대한치과보철학회지 Vol.46 No.6

STATEMENT OF PROBLEM: The discoloration of anterior teeth restoration is one of the material problems demanding retreatment. OBJECTIVES: To evaluate the color stability and affecting factors on esthetic restorative materials when subjected to accelerated aging. MATERIAL AND METHODS: This study was conducted using porcelain disks (IPS Empress 2-glazed, IPS Empress 2-polished), direct restorative resin disks (SYNERGY Duo) and indirect restorative resin disks (Sinfony, TESCERA ATL). Accelerated aging was done by precipitating the specimens in 38.C distilled water and irradiating with xenon light, and the total irradiation was 397.98 KJ/mm. Color and microhardness change of the specimens were measured before accelerated aging and after 100 hours, 200 hours and 300 hours of accelerated aging, and Surface of the specimens were examined with SEM before and after 300 hours of accelerated aging. RESULTS: 1. After 300 hours' accelerated aging, a ${\Delta}E$ value was 3.3 or lower in IPS Empress 2-glazed, IPS Empress 2-polished and Sinfony. 2. After 300 hours' accelerated aging, gloss was lost and surface changes including microcracks were observed in TESCERA ATL and SYNERGY Duo, and color changes of them ranged between 3.58 and 6.40 ${\Delta}E$ units. 3. During 300 hours' accelerated aging, the microhardness of surface was increased by 3.21 - 19.64% in all kinds of composites resin. CONCLUSION: After 300 hours' accelerated aging, SEM images IPS Empress 2-glazed, IPS Empress 2-polished and Sinfony showed little morphological change and their color changes were considered to be clinically acceptable. And there was significant correlation between microhardness changes and color changes of composites (P < .05).

복합 가속열화를 통한 배전용 고분자 피뢰기의 장기 열화특성 예측

김주용,권태호,박철배,김준일,Kim, Ju-Yong,Kwon, Tae-Ho,Park, Chul-Bae,Kim, Joon-Eel 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.8

In this study accelerated aging test equipment was developed to simulate domestic weather condition for accelerated aging test of polymer housed distribution surge arresters. Polymer arresters were aged for 3,000 hours by this test equipment and chemical and electrical characteristics analysis of surge arresters were conducted after aging test. In addition, performance assessment of outdoor installed arresters for 3 years was conducted to compare aging effect between accelerated aging test and natural aging. Through this experiment it is verified that the capability of the proposed aging test for simulating natural aging and the housing material and disconnector of domestic polymer arresters can be deteriorated by the long time field operation.

항노화 치료의 임상적 근거

박정현 대한노인재활의학회 2022 Geriatric rehabilitation Vol.12 No.1

Aging is a biological process driven by the many numbers of biological and genetic pathways, which are closely related to lifespan, and are a very strong risk factor for all age-related diseases. Human life expectancy has greatly increased, but this has not been accompanied by a similar increase in their healthspan. Aging is a driving factor of various age-related diseases, including neurodegenerative diseases, cardiovascular diseases, cancer, immune system disorders, and musculoskeletal disorders. Current advances in the preventive and therapeutic strategies for these age-related degenerative diseases are still incomplete, partially because of the aging process itself. Modification of aging process itself might have profound impact on the development and progression of age-related diseases. Researches to find out medications and strategies that improve the healthspan by targeting the aging itself have now become a very hot topic in the medical researches. In this review, the status of aging research and the efforts for the development of potential pharmacological interventions for the age-related diseases, such as metformin, rapamycin, resveratrol, senolytics, as well as caloric restriction, will be briefly summarized. The feasibility, side effects, and future potential of these treatments will be also discussed, which will provide a basis to develop novel anti-aging therapeutics for improving the healthspan and preventing aging-related diseases.

저출산ㆍ고령화에 따른 노동시장변화와 고령자 고용시스템의 개선

고준기 한국비교노동법학회 2006 노동법논총 Vol.10 No.-

Lower birth rate and longer average life span are driving our country to so called-Aging Society-step by step. In particular, Korea also becomes a country at the rapidest speed of the world in aging. Aging society involves many social and economic problems. So it requires national-wide political countermeasures. However, we have actually insufficient social security system against this aging society and have lack of employment even for the aged. In addition, the aged of ours mostly have insufficient or even poor financial conditions. That is why the aged in low income class may critically result in one of social problems. Furthermore, the retirement of the aged employee from economic activities may lead to lower population participating into economic activities. In fact, they have remarkably contributed to the economic growth of Korea over last four decades. If the aged are not properly employed, welfare budget will increase along with lower general labor productivity than now so that national development will remain at standstill. Accordingly, we have to make proactive efforts to enhance the employment of the aged. Methodologically, it is required to approach the employment of the aged in the level of alternative policy for relieving national and social sustenance expenses and overcoming lack of labor manpower, beyond existing social benefit level. For these purports, this study focuses on outlining basic characteristics of labor market for the aged in Korea and examining legal and political challenges in terms of labor market for the aged.

Age-related Increase of Sister Chromatid Exchange Frequency in Bone Marrow Cells of Senescence Accelerated Mouse and Its Inhibition by Chronic Treatment of Ginseng

Lim, Heung-Bin,Sohn, Hyung-Ok,Lee, Young-Gu,Kim, Seung-Hyung,Lee, Dong-Wook Korean Society of ToxicologyKorea Environmental Mu 1995 Toxicological Research Vol.11 No.2

Age-related change in the frequency of spontaneous sister chromatid exchange (SCE) and chromosornal aberrations were investigated in bone marrow cells of accelerated senescence-resistant mice (SAM R1) and senescence accelerated ones (SAM P1). And the effect of chronic treatment of ginseng extract (Panax ginseng C.A. Meyer) on these chromosomal abnormalities was tested in SAM P1. SCE frequency in the cells was progressively increased with age in both mice, but it was consistently higher in SAM P1 than in SAM R1 at all corresponding age. Chromosomal aberrations were, however, not significantly changed with age except that it was slightly increased in only aged SAM P1. Interestingly, the rate of these genetic instabilities in SAM P1 was remarkably retarded by long-term administration of ginseng water extract (0.05% in drinking water). These results suggest that frequency of spontaneous SCE in bone marrow cells increase in parallel with senescence of the mice, and SAM P1 is in the condition of being more exposed than SAM R1 to DNA damaging factors. These also indicate that long-term treatment of ginseng may reduce the genetic damage.

효모를 달리한 약주의 숙성 시 품질 변화

최정실,강지은,정석태 한국식품저장유통학회 2022 한국식품저장유통학회지 Vol.29 No.1

This study demonstrated the effects of different commercially available Saccharomyces cerevisiae yeasts i.e., Fermivin®, La Parisienne, Songcheon, Ottogi, and Chungmoo, on the variation in the quality of yakju samples under accelerated aging (45℃, 14 d). The analyses of physicochemical properties of the yakju samples were performed for, soluble solid content (°Brix), pH, total acid content (%, as acetic acid), alcohol (v/v%), volatile acid (mg/L), reducing sugar content (mg/mL), amino acidity (mL), brownness (A430), and hunter color value before and after aging. By comparing the results, significant differences in the properties of the yakju samples before and after aging were observed. The yakju sample fermented with wine-yeast Fermivin® exhibited no significant change in color after aging; furthermore, the reducing sugar content (1.20±0.01-1.32±0.03 mg/mL) and amino acidity (4.06±0.07-4.80±0.04 mL) of this sample were lower than those of the other samples. The yeast of Fermivin® resulted in a negligible residual sugar content owing to complete fermentation, thereby minimizing the variation in quality during aging. The using of different yeasts for fermentation induced significant differences in the contents of organic acid, free nitrogenous components, and volatile components before and after aging. The obtained results indicated that the properties of yakju such as odor and browning, could be regulated based on the type of yeast used for fermentation.

Persimmon Oligomeric Proanthocyanidins Extend Life Span of Senescence-Accelerated Mice

Takako Yokozawa,이영아,Qi Zhao,Kinzo Matsumoto,조은주 한국식품영양과학회 2009 Journal of medicinal food Vol.12 No.6

The anti-aging activities of persimmon oligomeric proanthocyanidins (POPs), reported to improve life span and behavioral characteristics associated with the aging process, were investigated using the senescence-accelerated mouse (SAM) P8, which is a good model for studies on aging-related behavioral changes as well as life span. We demonstrated that the administration of POPs extended the life span of SAMP8. In addition, POPs elevated Sirt1 expression, which is recognized as an essential factor for life span extension in the brain. On the other hand, the administration of POPs did not induce stereotypical behaviors such as rearing, jumping, and hanging from the lid of a cage, whereas food restriction increased these frequencies without a significant change in motor function. The present study suggests a promising role of POPs as anti-aging agents to extend life span, although further studies elucidating their anti-aging mechanisms acting are needed.

New Aging Index Using Signal Features of Both Photoplethysmograms and Acceleration Plethysmograms

안재목 대한의료정보학회 2017 Healthcare Informatics Research Vol.23 No.1

Objectives: Acceleration plethysmograms (APGs) are obtained by taking the second derivative of photoplethysmograms (PPGs) and are noninvasive circulatory signals related to risk factors for atherosclerosis with age. There has been growing interest in the development of mobile devices to collect and analyze PPG single features for ambulatory health monitoring. The present study aimed to extract a new feature from the morphologies of APG and PPG signals to classify the dominant indices related to the pulsatile volume of blood in tissue according to age. Methods: Ten APG and 14 PPG indices were simultaneously extracted. All indices were compared via Pearson correlation coefficients (r) and a regression analysis. We introduced a combined index extracted from both the PPG and APG indices defined as the inflection point area plus the d_peak (IPAD). The participants included 93 healthy adults aged 36–86 years with a mean ± standard deviation age of 57.43 ± 11.99 years. Results: The d_peak and age index for the APG indices were significantly correlated with age (r = –0.408, p < 0.0001 and r = 0.296, p = 0.0039, respectively). Only the A1 time for PPG indices was moderately correlated with age (r = –0.247, p = 0.017). The stiffness index, including individual height information, was not related to age (r = –0.031, p = 0.7713). However, the combined IPAD index was significantly more correlated with age (r = 0.56, p < 0.001) than the other indices. Conclusions: The proposed index outperformed the other 24 indices for evaluating vascular aging. We suggest that the IPAD is a significant factor related to the clinical information embedded in the PPG waveform.

Aging-related Changes of Inorganic Compound Leaching and Carbohydrates in Pyracantha angustifolia Seeds

Du Hyun Kim,Sim Hee Han 한국원예학회 2010 원예과학기술지 Vol.28 No.1

종자 활력의 지표를 개발하기 위해 피라칸사 종자를 35℃, 75% 상대습도 조건에 12일간 노화 처리 후 종자발아율, 무기성분누출과 탄수화물의 변화를 조사하였다. 노화처리로 인한 발아율의 감소는 Na?와 Ca²?의 누출량 증가를 동반하였으나, 전기전도도와 Na? 그리고 Mg²? 누출량과는 상관을 보이지 않았다. 발아율과 누출된 무기성분 비율(K?/Ca²?, K?/Na?, Mg²?/Ca²? 및 Mg²?/Na?)과 상관계수는 -0.75, -0.83, -0.79과 -0.79로 높게 나타났다. 또한 포도당 농도는 종자활력 감소와 관련이 있었으나, 전분과 자당 농도변화는 상관이 없었다. 누출된 무기성분 비율과 포도당 농도는 종자활력과 높은 상관을 보여서 피라칸사 종자활력의 측정에 지표로 제공될 수 있을 것이다. Changes of germination percentage, inorganic compound leaching, and carbohydrates were measured in Pyracantha angustifolia seeds throughout accelerated aging under 35℃ and 75% relative humidity (RH) to investigate whether these indicators can be used as a rapid vigor test. The decrease in seed germination was accompanied as increasing by Na? and Ca²? leakage concentration during artificial aging. However, the leachate electrical conductivity test and potassium and magnesium ion tests had no relation with seed germination. The ratios of inorganic ions from accelerated aged seeds show that K?/Ca²?, K?/Na?, Mg²?/Ca²?, and Mg²?/Na? were inversely correlated with germination and their correlation values were -0.75, -0.83, -0.79, and -0.79, respectively. Change in carbohydrates indicates that glucose concentration in aged seeds was associated with a decrease in seed vigor; however, the changes of sucrose and starch concentration did not show any relationship. In conclusion, the results show that, K?/Na?, K?/Ca²?, Mg²?/Ca²?, and Mg²?/Na? ratios and glucose concentration changes were highly correlated with seed vigor; thus, these changes could provide more sensitive and accurate index for the assessment of P. angustifolia seed vigor.

자연 노화된 니트로셀룰로오스의 수명에 관한 연구

김동성,진홍식 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.11

During the safety inspection of nitrocellulose-made explosive containers stored for more than 10 years, cracks were found in the containers. Therefore, a failure cause analysis test was performed. First, the cause of failure through the failure tree analysis was conducted to select the factors that influenced failure. The changes in the properties of the container caused by the acceleration of the reaction were found to be the cause of the failure by confirming the influence on the environment and internal/external factors that may occur during storage. To confirm this, environmental tests, such as thermal shock test and vacuum thermal stability test, were performed using a naturally aged container to analyze the cause of failure, and an accelerated aging test was performed to reproduce the failure. Through this, the chemical reaction was accelerated by heat and charge, as in the result of the fault tree analysis, and it was confirmed that the physical properties of the container were changed. In addition, the service life of the container was estimated using the Arrhenius model for the storage life due to thermal aging. 10년 이상 보관된 니트로셀룰로오스 (Nitrocellulose, 니트로셀룰로오스) 재질의 화약용기 안전 검사를 진행하는 과정 중 화약이 보관되어진 용기에 균열이 발생한 것을 확인하여 고장 원인 분석 시험을 실시하였다. 고장이 발생한 데에 영향을 준 요인을 선별하기 위해 먼저 고장수목분석(Fault Tree Analysis, FTA)을 통해 고장 요인 및 원인에 대해 탐구하였으며, 보관 시 발생할 수 있는 내 ‧ 외부적인 요인 및 환경에 대한 영향성을 확인한 결과 열에 의해 화학 반응이 가속화되어 발생한 화약용기의 물성 변화가 고장의 원인인 것으로 추정하였다. 이를 확인하기 위해 자연 노화된 화약용기를 이용하여 열충격시험, 양립성 시험 등의 환경시험을 수행하여 고장의 원인 분석을 수행하였으며, 가속노화시험을 통해 고장 재현 시험을 실시하였다. 이를 통해 앞선 고장수목분석 결과와 같이 열과 화약에 의해 화학 반응이 가속화되는 것을 확인할 수 있었으며, 화약용기의 물성이 변화하는 것을 확인하였다. 또한, 열 노화에 의한 수명 추정을 위해 아레니우스 모델(Arrhenius Model)을 이용하여 화약용기의 사용 수명을 추정하였다.