• Title/Summary/Keyword: aging treatment

Search Result 1,525, Processing Time 0.025 seconds

Repair bond strengths of non-aged and aged resin nanoceramics

  • Subasi, Meryem Gulce;Alp, Gulce
    • The Journal of Advanced Prosthodontics
    • /
    • v.9 no.5
    • /
    • pp.364-370
    • /
    • 2017
  • PURPOSE. To explore the influence of different surface conditionings on surface changes and the influence of surface treatments and aging on the bond strengths of composites to non-aged and aged resin nanoceramics. MATERIALS AND METHODS. Rectangular-shaped non-aged and aged (5000 thermocycles) resin nanoceramic specimens (Lava Ultimate) (n=63, each) were divided into 3 groups according to surface treatments (untreated, air abrasion, or silica coating) (n=21). The surface roughness was measured and scanning electron microscopy was used to examine one specimen from each group. Afterwards, the specimens were repaired with a composite resin (Filtek Z550) and half were sent for aging (5000 thermocycles, n=10, each). Shear bond strengths and failure types were evaluated. Roughness and bond strength were investigated by two- and three-way analysis of variance, respectively. The correlation between the roughness and bond strength was investigated by Pearson's correlation test. RESULTS. Surface-treated samples had higher roughness compared with the untreated specimens (P=.000). For the non-aged resin nanoceramic groups, aging was a significant factor for bond strength; for the aged resin nanoceramic groups, surface treatment and aging were significant factors. The failures were mostly adhesive after thermal cycling, except in the non-aged untreated group and the aged air-abraded group, which had mostly mixed failures. Roughness and bond strength were positively correlated (P=.003). CONCLUSION. Surface treatment is not required for the repair of non-aged resin nanoceramic; for the repair of aged resin nanoceramic restorations, air abrasion is recommended.

A Study on the Precipitation Behavior of $L2_1$-type $Ni_2AlTi$ Phase in B2-Ordered NiAl System (B2-규칙 NiAl계에 $L2_1$$Ni_2AlTi$상의 석출거동에 관한 연구)

  • Han, Chang-Suk
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.20 no.4
    • /
    • pp.187-194
    • /
    • 2007
  • A transmission electron microscope (TEM) investigation has been performed on the precipitation of $L2_1$-type $Ni_2AlTi$ phase in B2-ordered NiAl system. The hardness after solution treatment is high in NiAl-Ti alloys suggesting the large contribution of solid solution strengthening in this alloy system. However, the amount of age hardening is not large as compared to the large microstructural variations during aging. At the beginning of aging, the $L2_1$-type $Ni_2AlTi$ precipitates keep a lattice coherency with the NiAl matrix. By longer periods of aging $Ni_2AlTi$ precipitates lose their coherency and change their morphology to the globular ones surrounded by misfit dislocations. Misfit dislocations, which are observed on {100} planes of H-precipitates have the Burgers vector of a <100> with a pure edge type. The lattice misfits of NiAl-$Ni_2AlTi$ system is estimated from the spacings of misfit dislocations to be 1.1% at 1273 K. The lattice misfits decrease with increasing aging temperature in this system.

Strengthening Performance of Aged Papers with Chemical Strengthening Treatments (화학적 보강 방법에 따른 열화 종이의 보강 특성)

  • Lee, Hyeyoon;Lee, Jegon;Kim, Minsu;Sim, Kyujeong;Youn, Hye Jung
    • Journal of Korea Technical Association of The Pulp and Paper Industry
    • /
    • v.46 no.5
    • /
    • pp.35-42
    • /
    • 2014
  • Many historical archives have been deteriorated by aging with time. Various kinds of defects such as worm-hole, yellowing, brittleness are observed and their severity was dependent on raw material type, storage condition, and so on. For a long-term use and storage, a proper preservation treatment is required. Many studies on preservation and conservation have been carried out on hanji which was made from mulberry fiber, but there are few concerns on foreign paper. Therefore, aging and chemical strengthening treatment was done on paper made of bamboo and wood fibers depending on aging condition, the type and pickup weight of chemicals and treatment method. When methyl cellulose was treated with impregnation or brushing, the aged paper was strengthened effectively. The strengthening effect by chemicals was dependent on the aged condition of the paper.

Effect of Additional Cu and Natural Aging Treatment on Thermal Diffusivity in the Al-Mg-Si Alloy (Al-Mg-Si 합금에서 Cu 첨가와 자연시효 열처리가 열확산도에 미치는 영향)

  • Kim, Yu-Mi;Choi, Se-Weon
    • Journal of Korea Foundry Society
    • /
    • v.41 no.6
    • /
    • pp.528-534
    • /
    • 2021
  • To confirm effects of natural and artificial aging of precipitate on thermal diffusivity and hardness, the studied Al-Mg-Si alloy were manufactured by gravity casting method with 0.6 wt% and 1.0 wt% additional Cu element. The samples were used for measuring thermal diffusivity and hardness. The addition of Cu, promoted by intermediates such as Q'' and θ'' phases, contributing to the improvement of hardness and high-temperature thermal diffusivity. The natural aging decreased the hardness of the Al-Mg-Si-Cu alloys with increasing time, but did not affect the thermal diffusivity.

A Study for Aging Factor of Bulletproof Helmet : High Temperature Treatment (방탄헬멧의 노화인자에 관한 연구 : 고온 환경 처리를 중심으로)

  • Park, Ho Yun;Gu, Seung Hwan
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.21 no.6
    • /
    • pp.332-339
    • /
    • 2020
  • This study was a prior study to establish the shelf life of bulletproof helmets, considered the aging factor of bulletproof helmets. To estimate the aging factor of bulletproof helmets, we established a hypothesis that the 'temperature' factor would have the greatest impact on the shelf life of the bulletproof helmet, considering the environmental treatment of the American army's bulletproof helmet's materials. To verify the hypothesis, high temperature acceleration environmental treatment of bulletproof helmets was performed, and the Arrhenius formula was applied to calculate the shelf life. The study result confirmed the negative correlation between bulletproof performance and high temperature, and the influence of temperature as an aging factor was not significant by deriving life by using the Arrhenius model. The limitation of this study is that we couldn't obtain enough samples due to the specificity (miliary supplies) of the test subjects. However, given that the life-related research on bulletproof helmets has not been carried out, this research has great implications and could be used as a reference for improving the Korean Army's bulletproof helmet specifications.

Changes in Reducing Sugar and Catalpol Contents of Rehmannia Root Slurry with Aging Treatments (숙성처리에 따른 지황 슬러리의 환원당 및 카탈폴 변화)

  • Jang, Gwi Yeong;Kim, Dong Hwi;Park, Chan Hum;Shin, Yu Su;Kang, Tae Su;Jeong, Heon Sang;Choi, Jehun
    • The Korean Journal of Food And Nutrition
    • /
    • v.31 no.4
    • /
    • pp.559-564
    • /
    • 2018
  • Rehmannia glutinosa root (R. root) has been used as an traditional medicine, and is important resource for natural medicines and functional foods. However, R. root contains catalpol which is bitter, and undigested sugars, including stachyose and raffinose, which can cause diarrhea. Therefore, this study was performed to identify the changes in reducing sugar from undigested sugars and in catalpol contents in R. root slurry induced by aging treatments. R. root slurry was treated at $10{\sim}70^{\circ}C$ for up to 72 hr; and extracted with a 50% ethanol solution. The catalpol content was analyzed using HPLC-UVD. Reducing sugar content generated from undigested sugars was measured by the Nelson-Somogyi methods, and the reaction rates were calculated from their variation according to aging time and temperature. During the aging treatment, reducing sugar increased and catalpol decreased. Their formation and degradation rates were highest at $50^{\circ}C$ and $30{\sim}40^{\circ}C$, and their rates were $2.05mg/g{\cdot}hr$ and 23.09 to 23.33%/hr, respectively. These results indicated that aging treatment can positively affect the sweetness and digestibility of R. root slurry. Therefore, an aging treatment could be considered for improving the taste and digestibility of R. root.

Oligonol promotes anti-aging pathways via modulation of SIRT1-AMPK-Autophagy Pathway

  • Park, Seul-Ki;Seong, Rak-Kyun;Kim, Ji-Ae;Son, Seok-Jun;Kim, Younghoon;Yokozawa, Takako;Shin, Ok Sarah
    • Nutrition Research and Practice
    • /
    • v.10 no.1
    • /
    • pp.3-10
    • /
    • 2016
  • BACKGROUND/OBJECTIVES: Oligonol, mainly found in lychee fruit, is an antioxidant polyphenolic compound which has been shown to have anti-inflammatory and anti-cancer properties. The detailed mechanisms by which oligonol may act as an anti-aging molecule have not been determined. MATERIALS/METHODS: In this study, we evaluated the ability of oligonol to modulate sirtuin (SIRT) expression in human lung epithelial (A549) cells. Oligonol was added to A549 cells and reactive oxygen species production, mitochondrial superoxide formation, and p21 protein levels were measured. Signaling pathways activated upon oligonol treatment were also determined by western blotting. Furthermore, the anti-aging effect of oligonol was evaluated ex vivo in mouse splenocytes and in vivo in Caenorhabditis elegans. RESULTS: Oligonol specifically induced the expression of SIRT1, whose activity is linked to gene expression, metabolic control, and healthy aging. In response to influenza virus infection of A549 cells, oligonol treatment significantly up-regulated SIRT1 expression and down-regulated viral hemagglutinin expression. Oligonol treatment also resulted in the activation of autophagy pathways and the phosphorylation of AMP-activated protein kinase (AMPK). Furthermore, oligonol-treated spleen lymphocytes from old mice showed increased cell proliferation, and mRNA levels of SIRT1 in the lungs of old mice were significantly lower than those in the lungs of young mice. Additionally, in vivo lethality assay revealed that oligonol extended the lifespan of C. elegans infected with lethal Vibrio cholerae. CONCLUSIONS: These data demonstrated that oligonol may act as an anti-aging molecule by modulating SIRT1/autophagy/AMPK pathways.

The effect of welding heat input and heat-treatment on the strength of the electron beam welded $175Kg/mm^2$ maraging steel sheet (전자비임용접한 $175Kg/mm^2$급 박판 Maraging강의 이음강도에 미치는 용접입열 및 열처리의 영향)

  • 윤한상;정병호;배차헌
    • Journal of Welding and Joining
    • /
    • v.4 no.2
    • /
    • pp.21-29
    • /
    • 1986
  • The influence of welding heat input variation(600-900J/cm) and heat-treatment condition after welding on tensile strength of butt welded joint in $175Kg/mm^2$ strength level Maraging steel(Co-free and Co-containing) sheets was investigated on the basis of hardness distribution, microstructure of weld metal and fracture surface. The obtained main results are as follows; 1. The strength of weldment (UTS, NTS), joint efficiency showed a little decreasing tendency with the increase in welding heat input, and the elongation showed a little increasing tendency with the increase in the width of weld metal. It was considered because of the plastic constraint of the high strength base metal. 2. The strength of weldment was better in the solution treatment and aging than the aging only after welding due to the disappearance of almost denverite in weld metal. 3. The hardness distribution in weldment after welding and heat-treatment was almost similar to both Co containing and Co free Maraging steel with change in welding heat input. 4. The fracture was occurred at weld metal, and the fracture surface showed a relatively shallow dimples in both Co containing and Co free Maraging steel.

  • PDF

Heat Treatment of AZ91-5wt.%Sn Magnesium Alloy (AZ91-5wt.%Sn 마그네슘 합금의 열처리의 특성)

  • Kim, Dae-Hwan;Lim, Su-Gun
    • Journal of Korea Foundry Society
    • /
    • v.37 no.1
    • /
    • pp.14-20
    • /
    • 2017
  • The microstructure, electrical conductivity and hardness variation of an AZ91-5wt%Sn Mg alloy sample during a solid-solution and aging heat treatment were instigated by optical microscopy, scanning electron microscopy, X-ray diffraction and by Rockwell hardness techniques in this study. The XRD result shows that the main phases in the as-casted alloy are ${\alpha}$-Mg, $Mg_{17}Al_{12}$ and $Mg_2Sn$. From the SEM images of the AZ91-5wt%Sn Mg alloy after the solution treatment, the $Mg_{17}Al_{12}$ phases in the alloy were found to have dissolved into the matrix with an increase in the holding time during the solution treatment, but $Mg_2Sn$ phases were clearly observable. The highest peak hardness of the AZ91-5wt%Sn Mg alloy is 82HRE at an aging temperature of $200^{\circ}C$.

Short-term Treatment of Daumone Improves Hepatic Inflammation in Aged Mice

  • Park, Jong Hee;Ha, Hunjoo
    • The Korean Journal of Physiology and Pharmacology
    • /
    • v.19 no.3
    • /
    • pp.269-274
    • /
    • 2015
  • Chronic inflammation has been proposed as one of the main molecular mechanisms of aging and age-related diseases. Although evidence in humans is limited, short-term calorie restriction (CR) has been shown to have anti-inflammatory effects in aged experimental animals. We reported on the long-term treatment of daumone, a synthetic pheromone secreted by Caenorhabditis elegans in an energy deficient environment, extends the life-span and attenuates liver injury in aged mice. The present study examined whether late onset short-term treatment of daumone exerts anti-inflammatory effects in the livers of aged mice. Daumone was administered orally at doses of 2 or 20 mg/kg/day for 5 weeks to 24-month-old male C57BL/6J mice. Increased liver macrophage infiltration and gene expression of proinflammatory cytokines in aged mice were significantly attenuated by daumone treatment, suggesting that short-term oral administration of daumone may have hepatoprotective effects. Daumone also dose-dependently suppressed tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$ )-induced nuclear factor-${\kappa}B$ (NF-${\kappa}B$) phosphorylation in HepG2 cells. The present data demonstrated that short-term treatment of daumone has anti-inflammatory effects in aged mouse livers possibly through suppression of NF-${\kappa}B$ signaling and suggest that daumone may become a lead compound targeting aging and age-associated diseases.