• Title, Summary, Keyword: Degradation

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Biodegradability of Polylactic Acid Fabrics by Enzyme Hydrolysis and Soil Degradation

  • Lee, So Hee
    • Textile Coloration and Finishing
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    • v.29 no.4
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    • pp.181-194
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    • 2017
  • The biodegradability of polylactic acid(PLA) fabrics was evaluated by two methods: enzyme and soil degradation. Three different enzymes were selected to evaluate. Degradation times were measured at optimal enzyme treatment conditions. Biodegradation by enzymatic hydrolysis was compared with soil degradation. As a result, biodegradation created cracks on the fiber surface, which led to fiber thickening and shortening. In addition, new peak was observed at $18.5^{\circ}$ by degradation. Moreover, cracks indicating biofragmentation were confirmed by enzyme and soil degradation. By enzyme and soil degradation, the weight loss of PLA fabrics was occurred, there through, the tensile strength decreased about 25% by enzyme hydrolysis when 21 days after, and 21.67% by soil degradation when 60 days after. Furthermore, the biodegradability of PLA fabrics by enzymatic and soil degradation was investigated and enzymatic degradation was found to be superior to soil degradation of PLA fabrics. Among the three enzymes evaluated for enzymatic degradation, alcalase was the most efficient enzymes. This study established the mechanism of biodegradation of PLA nonwovens, which might prove useful in the textile industry.

Effect of Electrode Degradation on the Membrane Degradation in PEMFC (PEMFC에서 전극 열화가 전해질 막 열화에 미치는 영향)

  • Song, Jinhoon;Kim, Saehoon;Ahn, Byungki;Ko, Jaijoon;Park, Kwonpil
    • Korean Chemical Engineering Research
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    • v.51 no.1
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    • pp.68-72
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    • 2013
  • Until a recent day, degradation of PEMFC MEA (membrane and electrode assembly) has been studied, separated with membrane degradation and electrode degradation, respectively. But membrane and electrode were degraded coincidentally at real PEMFC operation condition. During simultaneous degradation, there was interaction between membrane degradation and electrode degradation. The effect of electrode degradation on membrane degradation was studied in this work. We compared membrane degradation after electrode degradation and membrane degradation without electrode degradation. I-V performance, hydrogen crossover current, fluoride emission rate (FER), impedance and TEM were measured after and before degradation of MEA. Electrode degradation reduced active area of Pt catalyst, and then radical/$H_2O_2$ evolution rate decreased on Pt. Decrease of radical/$H_2O_2$ reduced the velocity of membrane degradation.

Discussion on the Technology Route for Land Degradation Monitoring and Assessment based on 3S Technique

  • Jing, Wang;Ting, He;Zhang, Ji-Xian;Li, Hai-Tao
    • Proceedings of the KSRS Conference
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    • pp.757-765
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    • 2002
  • This paper analyzes three theories for land degradation assessment and internationl/domestic methods for land degradation monitoring and assessment. Under the guidance of absolute degradation thought, this paper proposes the technological framework for monitoring and appraising cultivated land degradation based on the 3S technique. We can apply 3S technique and analyze the nature, the environmental, the social, and the economic elements which influence the land utilization and degradation synthetically, to set up the indicator system of the cultivated land degradation monitoring and assessment based on 3S technique; to propose the degradation information extraction methods based on 3S technique; to create the quantitative assessment model and method for land degradation; to analyze the ecological environment response of land use and degradation quantitatively; and to propose the measure, policy and suggestion for solving the land degradation problem from the point of view of land utilization.

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Regulation of Protein Degradation by Proteasomes in Cancer

  • Jang, Ho Hee
    • Journal of Cancer Prevention
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    • v.23 no.4
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    • pp.153-161
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    • 2018
  • Imbalance of protein homeostasis (proteostasis) is known to cause cellular malfunction, cell death, and diseases. Elaborate regulation of protein synthesis and degradation is one of the important processes in maintaining normal cellular functions. Protein degradation pathways in eukaryotes are largely divided into proteasome-mediated degradation and lysosome-mediated degradation. Proteasome is a multisubunit complex that selectively degrades 80% to 90% of cellular proteins. Proteasome-mediated degradation can be divided into 26S proteasome (20S proteasome + 19S regulatory particle) and free 20S proteasome degradation. In 1980, it was discovered that during ubiquitination process, wherein ubiquitin binds to a substrate protein in an ATP-dependent manner, ubiquitin acts as a degrading signal to degrade the substrate protein via proteasome. Conversely, 20S proteasome degrades the substrate protein without using ATP or ubiquitin because it recognizes the oxidized and structurally modified hydrophobic patch of the substrate protein. To date, most studies have focused on protein degradation via 26S proteasome. This review describes the 26S/20S proteasomal pathway of protein degradation and discusses the potential of proteasome as therapeutic targets for cancer treatment as well as against diseases caused by abnormalities in the proteolytic system.

Analysis of Degradation Data Using Robust Experimental Design (강건 실험계획법을 이용한 열화자료의 분석)

  • 서순근;하천수
    • Journal of the Korean Society for Quality Management
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    • v.32 no.1
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    • pp.113-129
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    • 2004
  • The reliability of the product can be improved by making the product less sensitive to noises. Especially, it Is important to make products robust against various noise factors encountered in production and field environments. In this paper, the phenomenon of degradation assumes a simple random coefficient degradation model to present analysis procedures of degradation data for robust experimental design. To alleviate weak points of previous studies, such as Taguchi's, Wasserman's, and pseudo failure time methods, novel techniques for analysis of degradation data using the cross array that regards amount of degradation as a dynamic characteristic for time are proposed. Analysis approach for degradation data using robust experimental design are classified by assumptions on parametric or nonparametric degradation rate(or slope). Also, a simulation study demonstrates the superiority of proposed methods over some previous works.

Towards improved models of shear strength degradation in reinforced concrete members

  • Aschheim, Mark
    • Structural Engineering and Mechanics
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    • v.9 no.6
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    • pp.601-613
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    • 2000
  • Existing models for the shear strength degradation of reinforced concrete members present varied conceptual approaches to interpreting test data. The relative superiority of one approach over the others is difficult to determine, particularly given the sparseness of ideal test data. Nevertheless, existing models are compared using a suite of test data that were used for the development of one such model, and significant differences emerge. Rather than relying purely on column test data, the body of knowledge concerning degradation of concrete as a material is considered. Confined concrete relations are examined to infer details of the degradation process, and to establish a framework for developing phenomenologically-based models for shear strength degradation in reinforced concrete members. The possibility of linking column shear strength degradation with material degradation phenomena is explored with a simple model. The model is applied to the results of 7 column tests, and it is found that such a link is sustainable. It is expected that models founded on material degradation phenomena will be more reliable and more broadly applicable than the current generation of empirical shear strength degradation models.

Degradation Accelerated Stress Test of Electrode and Membrane in PEMFC (PEMFC에서 전극과 전해질 막의 열화 가속 시험)

  • Song, Jin-Hoon;Kim, Sae-Hoon;Ahn, Byung-Ki;Ko, Jai-Joon;Park, Kwon-Pil
    • Korean Chemical Engineering Research
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    • v.50 no.5
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    • pp.778-782
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    • 2012
  • Until a recent day, degradation of PEMFC MEA (membrane and electrode assembly) has been studied, separated with membrane degradation and electrode degradation, respectively. But membrane and electrode were degraded coincidentally at real PEMFC operation condition. Therefore in this work, AST (Accelerated Stress Test) of MEA degradation was done at the condition that membrane and electrode were degraded simultaneously. There was interaction between membrane degradation and electrode degradation. Membrane degradation reduced the decrease range of catalyst active area by electrode degradation. Electrode degradation reduces increase range of the hydrogen crossover current and FER (Fluoride Emission Rate) by membrane degradation.

Effect of Membrane Degradation on the Electrode Degradation in PEMFC (PEMFC에서 막 열화가 전극 열화에 미치는 영향)

  • Song, Jinhoon;Jeong, Jaejin;Jeong, Jaehyeun;Kim, Saehoon;Ahn, Byungki;Ko, Jaijoon;Park, Kwonpil
    • Korean Chemical Engineering Research
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    • v.51 no.3
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    • pp.325-329
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    • 2013
  • The membrane and electrode were degraded coincidentally at real PEMFC(Proton Exchange Membrane Fuel Cells) operation condition. But the interaction membrane degradation between electrode degradation has not been studied. The effect of membrane degradation on electrode degradation was studied in this work. We compared electrode degradation after membrane degradation and electrode degradation without membrane degradation. I-V performance, hydrogen crossover current, impedance and TEM were measured after and before degradation of MEA. Membrane degradation enhanced hydrogen crossover, and then Pt particle growth rate was reduced. Increase of hydrogen crossover by membrane degradation reduced the electrode degradation rate.

Application of Accelerated Degradation Testing for VFD (Vacuum Fluorescent Display) (VFD(Vacuum Fluorescent Display) 가속열화시험 응용사례)

  • Bae, Suk-Joo
    • Journal of Applied Reliability
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    • v.5 no.4
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    • pp.413-425
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    • 2005
  • As an alternative to traditional life testing, degradation tests can be effective in assessing product reliability when measurements of degradation leading to failure can be observed. This article presents an accelerated degradation testing for vacuum fluorescent displays (VFDs). The accelerated degradation model is based on Arrhenius-lifetime relationship for cathode temperatures. We compare the results between accelerated degradation test and test at normal use condition. Accelerated degradation test for display devices is observed as an efficient method to warrantee product reliability to customers, as well as a tool to save time and costs.

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Degradation Mechanism of ZnO Ceramic Varistors with the Time on the DC Stress Test (DC 스트레스 시간에 따른 ZnO 세라믹 바리스터의 열화기구)

  • 소순진;김영진;소병문;박춘배
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.857-860
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    • 2000
  • The objective of this paper is to demonstrate degradation phenomena through DC degradation tests and predicts degradation phenomena as a function of time from the tests. The ZnO varistor used in this investigation were fabricated by standard ceramic techniques. Especial, these were sintered in nitrogen atmosphere, at 2 h, for $1300^{\circ}C$. The conditions of DC degradation test were 115$\pm$$2^{\circ}C$for 0, 2, 4, and 8 h, respectively. To demonstrate the degradation phenomena of ZnO varistors, Voltagecurrent analyses were performed before and after the degradation test, and frequency analyses were used with the time of the degradation tests. It was found that the degradation occurred in not grain but grain boundary and the degradation behavior of varistors was unsymmetrically degraded with the direction of tests.

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