• Title, Summary, Keyword: Thermal Stability

Search Result 3,332, Processing Time 0.051 seconds

Some Molecular Characteristics and Improving Methods for Thermal Stability of Enzyme (효소단백질 열안정성의 분자구조적 특성 및 증진기법)

  • 김남수;김수일
    • Microbiology and Biotechnology Letters
    • /
    • v.19 no.1
    • /
    • pp.100-108
    • /
    • 1991
  • Molecular characteristics and improving methods for thermal stability of enzyme have been considered. Intrinsic and extrinsic stabilizing mechanisms are two governing principles for enhanced thermal stability of enzyme in molecular basis. Factors contributing to the former and the latter mechanisms may be involved in the enhanced thermal stability of enzyme complementarily. Also, the methods for improving thermal stability of enzyme which comprise reaction in organic solvent system, chemical modification, immobilization, sequential unfolding and refolding, gene manipulation techniques and enzyme-antibody complexing are reviewed.

  • PDF

Stress Dependence of Thermal Stability of Nickel Silicide for Nano MOSFETs

  • Zhang, Ying-Ying;Lim, Sung-Kyu;Lee, Won-Jae;Zhong, Zhun;Li, Shi-Guang;Jung, Soon-Yen;Lee, Ga-Won;Wang, Jin-Suk;Lee, Hi-Deok
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.15-16
    • /
    • 2006
  • The thermal stability of nickel silicide with compressively and tensilely stressed nitride capping layer has been investigated in this study. The Ni (10 nm) and Ni/Co/TiN (7/3/25 nm) structures were deposited on the p-type Si substrate. The stressed capping layer was deposited using plasma enhanced chemical vapor deposition (PECVD) after silicide formation by one-step rapid thermal process (RTP) at $500^{\circ}C$ for 30 sec. It was found that the thermal stability of nickel silicide depends on the stress induced by the nitride capping layer. In the case of Ni (10 nm) structure, the high compressive sample shows the best thermal stability, whereas in the case of Ni/Co/TiN (7/3/25 nm) structure, the high compressive sample shows the worst thermal stability.

  • PDF

A Study on Dimensional Stability and Thermal Performance of Superheated Steam Treated and Thermal Compressed Wood

  • Chung, Hyunwoo;Han, Yeonjung;Park, Jun-Ho;Chang, Yoon-Seong;Park, Yonggun;Yang, Sang-Yun;Yeo, Hwanmyeong
    • Journal of the Korean Wood Science and Technology
    • /
    • v.44 no.2
    • /
    • pp.184-190
    • /
    • 2016
  • Recently, wood is attracting attention as green building interior decoration material. When wood is used as building interior decoration material, excellent dimensional stability and thermal performance is required. In this study, superheated steam treatment process and thermal compression process were applied to flat sawn Pinus koraiensis wood panel in order to improve dimensional stability and thermal performance. According to results of this study, superheated steam treatment process and thermal compression process improve thermal performance and dimensional stability of wood, especially in tangential direction. The spring back in radial direction reduces the effect of thermal compression on dimensional stability of wood in radial direction.

Evaluation of thermal stability of quasi-isotropic composite/polymeric cylindrical structures under extreme climatic conditions

  • Gadalla, Mohamed;El Kadi, Hany
    • Structural Engineering and Mechanics
    • /
    • v.32 no.3
    • /
    • pp.429-445
    • /
    • 2009
  • Thermal stability of quasi-isotropic composite and polymeric structures is considered one of the most important criteria in predicting life span of building structures. The outdoor applications of these structures have raised some legitimate concerns about their durability including moisture resistance and thermal stability. Exposure of such quasi-isotropic composite/polymeric structures to various and severe climatic conditions such as heat flux and frigid climate would change the material behavior and thermal viability and may lead to the degradation of material properties and building durability. This paper presents an analytical model for the generalized problem. This model accommodates the non-linearity and the non-homogeneity of the internal heat generated within the structure and the changes, modification to the material constants, and the structural size. The paper also investigates the effect of the incorporation of the temperature and/or material constant sensitive internal heat generation with four encountered climatic conditions on thermal stability of infinite cylindrical quasi-isotropic composite/polymeric structures. This can eventually result in the failure of such structures. Detailed critical analyses for four case studies which consider the population of the internal heat generation, cylindrical size, material constants, and four different climatic conditions are carried out. For each case of the proposed boundary conditions, the critical thermal stability parameter is determined. The results of this paper indicate that the thermal stability parameter is critically dependent on the cylinder size, material constants/selection, the convective heat transfer coefficient, subjected heat flux and other constants accrued from the structure environment.

Improved Thermal Stability of Ag Nanowire Heaters with ZnO Layer (ZnO를 이용한 은 나노와이어 히터의 열 안정성 향상)

  • Choi, Wonjung;Jo, Sungjin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.30 no.8
    • /
    • pp.530-534
    • /
    • 2017
  • Transparent film heaters employing silver nanowires (Ag NWs) have attracted increasing attention because of their widespread applications. However, the low thermal resistance of Ag NWs limits the maximum operating temperature of the Ag NW film heater. In this study, Ag NW film heaters with high mechanical and thermal stability were successfully developed. The thermal power-out characteristics of the Ag NW heaters were investigated as a function of the Ag NW density. The results revealed that the prepared flexible Ag NW heater possessed high thermal stability over $190^{\circ}C$ owing to ZnO encapsulation. This indicates that the Ag NW film with excellent thermal stability have remarkably high potential for use as electrodes in film heaters operating at high temperatures.

Nonlocal strain gradient model for thermal stability of FG nanoplates integrated with piezoelectric layers

  • Karami, Behrouz;Shahsavari, Davood
    • Smart Structures and Systems
    • /
    • v.23 no.3
    • /
    • pp.215-225
    • /
    • 2019
  • In the present paper, the nonlocal strain gradient refined model is used to study the thermal stability of sandwich nanoplates integrated with piezoelectric layers for the first time. The influence of Kerr elastic foundation is also studied. The present model incorporates two small-scale coefficients to examine the size-dependent thermal stability response. Elastic properties of nanoplate made of functionally graded materials (FGMs) are supposed to vary through the thickness direction and are estimated employing a modified power-law rule in which the porosity with even type of distribution is approximated. The governing differential equations of embedded sandwich piezoelectric porous nanoplates under hygrothermal loading are derived through Hamilton's principle where the Galerkin method is applied to solve the stability problem of the nanoplates with simply-supported edges. It is indicated that the thermal stability characteristics of the porous nanoplates are obviously influenced by the porosity volume fraction and material variation, nonlocal parameter, strain gradient parameter, geometry of the nanoplate, external voltage, temperature and humidity variations, and elastic foundation parameters.

Effects of Zeolites on Thermal Stability of Poly(vinyl chloride) (폴리염화비닐(PVC)의 열안정성에 제올라이트가 미치는 영향)

  • Xu, Jiayou;Liang, Qinghua;Xian, Xiumei;Li, Kaidan;Liu, Jie
    • Polymer Korea
    • /
    • v.39 no.1
    • /
    • pp.1-5
    • /
    • 2015
  • The effects of zeolite on the thermal stability of poly(vinyl chloride) (PVC) were investigated by the static thermal stability test, pyrolysis experiment and ultraviolet spectrum. The results showed that the porous zeolite could absorb hydrogen chloride (HCl), which suppressed the catalysis of HCl on thermal degradation of PVC, thus improved the thermal stability of PVC. The oxidizing acid which was loaded on zeolite had oxidated on the double bond that formed during the dehydrochlorination of PVC. This process could prohibit the growth of the conjugated polyene and improved the color of PVC. Hence, zeolite might be possible to come up with a high performance thermal stabilizer.

The Effect of Suspension Stability on the Thermal Conductivity Enhancement of Water-based Au Nanofluids (물-기반 금나노유체의 분산안정성이 열전도도에 미치는 영향)

  • Choi, Tae Jong;Kim, Hyun Jin;Lee, Seung-Hyun;Park, Yong Jun;Jang, Seok Pil
    • Journal of ILASS-Korea
    • /
    • v.21 no.2
    • /
    • pp.111-115
    • /
    • 2016
  • This paper experimentally reports the effect of suspension stability on the thermal conductivity of water-based Au nanofluids. For this purpose, the water-based Au nanofluids are prepared by the one-step method called electro-chemical method with volume fraction of 0.0005%. The thermal conductivity of water-based Au nanofluids is measured from $22^{\circ}C$ to $42^{\circ}C$ using the transient hot wire method. To quantify the suspension stability of Au nanofluids, the suspension stability of nanofluids is evaluated using the in-house developed laser scattering system at a fixed wavelength of 632.8nm with the elapsed time. Based on the experimental results, the both thermal conductivity and suspension stability of water-based Au nanofluids are gradually decreased according to the time. These results experimentally show that the suspension stability of water-based Au nanofluids is the one of the important factor of thermal conductivity.

Studies on the Activity Properties of Pd-only Three-Way Catalyst for the Purification of Automobile Exhaust Emissions (자동차 배기가스 정화용 Pb-only 삼원촉매의 활성특성에 관한 연구)

  • 신병선;김상수;이길우;정명근;배재호;정석진
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.15 no.5
    • /
    • pp.667-676
    • /
    • 1999
  • The roles of ceria on three-way catalyst is to improve the noble metal dispersion and thermal stability of support ${\gamma}$-$Al_2O_3$. And, ceria has a oxygen storage capacity(OSC) under fuel rich/lean conditions to improve the operating windows of NOx, THC and CO conversion. However, ceria has weak thermal stability under high temperature due to the crystallite growth. So that, the OSC of ceria is decreased, and then the conversions of NOx, THC and CO is decreased. One way of enhancing the thermal stability and NOx, THC and CO conversion Pd-only catalyst is to improve as well as its thermal stability and oxygen storage capacity of the ceria. Especially, the appropriate mixing ratios of bulk and stabilized ceria are very important for designing principles of Pd-only three-way catalysts. In this paper, we discussed the thermal properties of stabilizedand unstabilized (bulk) ceria, and the oxygen storage capacity (OSC) of catalysts, and found the correlation between activity and the OSC of Pd-only catalysts with various different mixing ratios of bulk and stabilized ceria. Finally, we propose the design principles to improve the thermal stability of washcoated Pd-only catalysts.

  • PDF

Thermal Stability of Lithiated Silicon Anodes with Electrolyte

  • Park, Yoon-Soo;Lee, Sung-Man
    • Bulletin of the Korean Chemical Society
    • /
    • v.32 no.1
    • /
    • pp.145-148
    • /
    • 2011
  • The thermal behavior of lithiated Si anodes has been investigated using differential scanning calorimetry (DSC). In particular, the effect of Si particle size on the thermal stability of a fully lithiated Si electrode was investigated. For DSC measurements, a lithiated Si anode was heated in a hermetically sealed high-pressure pan with a polyvinylidene fluoride (PVDF) binder and a 1 M $LiPF_6$ solution in an ethylene carbonate (EC)-diethyl carbonate (DEC) mixture. The thermal evolution around $140^{\circ}C$ increases with lithiation and with decreasing particle size; this phenomenon is attributed to the thermal decomposition of the solid electrolyte interface (SEI) film. Exothermic peaks, following a broad peak at around $140^{\circ}C$, shift to a lower temperature with a decrease in particle size, indicating that the thermal stability of the lithiated Si electrode strongly depends on the Si particle size.