• 제목/요약/키워드: Heat resistant

검색결과 613건 처리시간 0.024초

발효유제품에서 박테리오파지의 특성, 검출과 제어 (The Characteristics, Detection and Control of Bacteriophage in Fermented Dairy Products)

  • 안성일;리합 아조니;트란 티 탄 후옌;곽해수
    • 한국축산식품학회지
    • /
    • 제29권1호
    • /
    • pp.1-14
    • /
    • 2009
  • This study was to review the classification, detection and control of bacteriophage in fermented dairy products. Bacteriophage has lytic and/or lysogenic life cycles. Epidemiologically speaking, detected major phages are c2, 936 and p335. Among them p335 has been the largest concern in dairy industry. Traditionally, various analytical technologies, such as spot, starter activity, indicator test, ATP measurement and conductimetric analysis, have been used for the phage detection. In recent years, advanced methods such as flow cytometric method, petrifilm, enzyme linked immunosorbent assay (ELISA) and multiflex PCR diagnostic kit have been deveoloped. The phage contamination has been controlled by using heat, high-pressure treatment, and the combinations of heat and pressure, and/or chemical. Also some starter cultures with phage-resistant character have been developed to minimize the concentration of phages in dairy product. Bacteriophage inhibition media such as calcium medium was also mentioned. To prevent the contamination of bacteriophage in dairy industry, further researches on the detection and control of phage, and phage resistant starters are necessary in the future.

A COMPARISON OF THE V4 STRAIN WITH THE CONVENTIONAL F1 AND M STRAIN OF NEWCASTLE DISEASE VACCINE IN RURAL BANGLADESH

  • Biswas, H.R.;Hoque, M.M.;Chowdhury, S.M.Z.H.;Oxley, M.E.;Rahman, M.M.
    • Asian-Australasian Journal of Animal Sciences
    • /
    • 제9권2호
    • /
    • pp.231-235
    • /
    • 1996
  • Bangladeshi indigenous chickens of mixed ages vaccinated twice at a three week interval with either conventional vaccines-$F_1$ (ocular) and M (mukteswar, Intramuscular), or heat resistant $V_4$ vaccine administered by either the ocular or oral routes, all showed satisfactory hemagglutination inhibition antibody (HI) responses and protection against Newcastle Disease (NCD) challenge persisting for four months. The antibody response to $F_1$ and M was higher than for $V_4$, which was similar whether administered by the ocular or oral routes. All vaccinated treatments have a significant level of protection compare to the control group (p<0.01). No significant difference (p>0.05) in the protection against controlled challenge with virulent NCD virus was found between vaccinated groups.

On-Site Corrosion Behavior of T91 Steel after Long-Term Service in Power Plant

  • He, Yinsheng;Chang, Jungchel;Lee, Je-Hyun;Shin, Keesam
    • 한국재료학회지
    • /
    • 제25권11호
    • /
    • pp.612-615
    • /
    • 2015
  • In this work, on-site corrosion behavior of heat resistant tubes of T91, used as components of a superheater in a power plant for up to 25,762 h, has been investigated using scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscattered diffraction(EBSD), with the objectives of studying the composition, phase distribution, and evolution during service. A multi-layer structure of oxide scale was found on both the steamside and the fireside of the tube surface; the phase distribution was in the order of hematite/magnetite/spinel from the outer to the inner matrix on the steamside, and in the order of slag/magnetite/spinel from the outer to the inner matrix on the fireside. The magnetite layer was found to be rich in pores and cracks. The absence of a hematite layer on the fireside was considered to be due to the low oxygen partial pressure in the corrosion environment. The thicknesses of the hematite and of the slag-deposit layer were found to exhibit no significant change with the increase of the service time.

금속계 마찰재와 제동디스크 간의 마찰특성 연구 (Study of Tribological Characteristics Between Metallic friction materials and Brake Disk)

  • 김상호;박형철;이희성
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2008년도 춘계학술대회 논문집
    • /
    • pp.2080-2093
    • /
    • 2008
  • 대표적으로 높은 운동에너지를 가지는 고속철도와 항공기의 제동장치에 적용되는 금속계 소결마찰재와 내열강 간의 트라이볼로지 특성 연구를 목적으로 각각 2종류의 고속철도용 금속계 마찰재와 항공기용 금속계 마찰재를 Lab-Scale Dynamometer를 이용하여 시험하였다. 그 결과 철도용 금속계 마찰재가 항공기용 마찰재에 비해 높은 마찰계수 및 마찰계수 안정성을 나타내었고, 마모량도 철도용 금속계 마찰재는 항공기용 마찰재에 비해 약 50%수준에 불과하여 본 시험조건에서는 철도용 소결마찰재가 뛰어난 것으로 나타났다. 또한, 동계 마찰재가 철계 마찰재보다 제동시 급격하게 온도가 상승하며, 냉각도 동계 마찰재가 빨리 되지만, 동계 마찰재라도 마찰재의 기지의 량에 따라 달라지는 것으로 나타났다. 마찰재에 따라 마찰면에 형성되는 산화피막의 안정성은 달라지는 것으로 나타났으며, 산화피막은 $Fe_2O_3$$Fe_3O_4$계통이며, 마찰재에 따라서 마모메카니즘이 달라지는 것으로 판단된다.

  • PDF

프런트 필라 트림의 내열특성 향상을 위한 순차적 실험계획법과 인공신경망 기반의 최적설계 (Optimum Design based on Sequential Design of Experiments and Artificial Neural Network for Heat Resistant Characteristics Enhancement in Front Pillar Trim)

  • 이정환;서명원
    • 한국정밀공학회지
    • /
    • 제30권10호
    • /
    • pp.1079-1086
    • /
    • 2013
  • Optimal mount position of a front pillar trim considering heat resistant characteristics can be determined by two methods. One is conventional approximate optimization method which uses the statistical design of experiments (DOE) and response surface method (RSM). Generally, approximated optimum results are obtained through the iterative process by a trial and error. The quality of results depends seriously on the factors and levels assigned by a designer. The other is a methodology derived from previous work by the authors, which is called sequential design of experiments (SDOE), to reduce a trial and error procedure and to find an appropriate condition for using artificial neural network (ANN) systematically. An appropriate condition is determined from the iterative process based on the analysis of means. With this new technique and ANN, it is possible to find an optimum design accurately and efficiently.

Mg-5Al-2Si 합금의 조직 및 부식특성에 미치는 Sb, Sr 첨가의 영향 (Effect of Sb and Sr Addition on Corrosion Properties of Mg-5Al-2Si Alloy)

  • 전종진;이상원;김병호;박봉규;박용호;박익민
    • 대한금속재료학회지
    • /
    • 제46권5호
    • /
    • pp.304-309
    • /
    • 2008
  • Magnesium alloys containing $Mg_2Si$ particles, as a promising cheap heat-resistant magnesium alloy for automobile power train parts applications, are attracting more attention of both material scientists and design engineers. Modification of the Chinese script shape $Mg_2Si$ particle is a key for using this alloy in sand or permanent mould casting. In the present work, the modification effect of Sr and Sb on the corrosion properties of the Mg-5Al-2Si alloy was investigated. Sr or Sb addition promoted the formation of fine polygonal shape $Mg_2Si$ particles by providing the nucleation sites. Sr was more effective element than Sb for shape modification of Chinese script shape $Mg_2Si$. Such improved microstructure of the modified alloy resulted in large improvement in corrosion resistance as compared to unmodified Mg-5Al-2Si alloy.

SiAlON의 절삭성능에 미치는 소결조제와 조성의 영향에 대한 연구 (Effect of Sintering Additive and Composition on Cutting Performance of SiAlON)

  • 최재형;이성민;남산;김성원
    • 한국분말재료학회지
    • /
    • 제26권5호
    • /
    • pp.415-420
    • /
    • 2019
  • SiAlON ceramics are used as ceramic cutting tools for heat-resistant super alloys (HRSAs) due to their excellent fracture toughness and thermal properties. They are manufactured from nitride and oxide raw materials. Mixtures of nitrides and oxides are densified via liquid phase sintering by using gas pressure sintering. Rare earth oxides, when used as sintering additives, affect the color and mechanical properties of SiAlON. Moreover, these sintering additives influence the cutting performance. In this study, we have prepared $Yb_{m/3}Si_{12-(m+n)}Al_{m+n}O_nN_{16-n}$ (m = 0.5; n = 0.5, 1.0) ceramics and manufactured SiAlON ceramics, which resulted in different colors. In addition, the characteristics of the sintered SiAlON ceramics such as fracture toughness and microstructure have been investigated and results of the cutting test have been analyzed.

Nb 첨가 오스테나이트계 내열 스테인리스강의 열기계적 피로 수명 및 변형 거동 (Endurance Life and Deformation Behavior under Thermo-mechanical Fatigue of Nb-added Heat Resistant Austenitic Stainless Steel)

  • 오용준;박중철;양원존
    • 대한금속재료학회지
    • /
    • 제49권7호
    • /
    • pp.541-548
    • /
    • 2011
  • Thermomechanical fatigue (TMF) behavior of heat resistant austenitic stainless steel was evaluated in the temperature range from 100$^{\circ}C$ to peak temperatures of 600 to 800$^{\circ}C$; The fatigue lives under TMF conditions were plotted against the plastic strain range and the dissipated energy per cycle. In the expression of the inelastic strain range versus fatigue life, the TMF data obtained at different temperature ranges were located close to a single line with a small deviation; however, when the dissipated energy per cycle, calculated from the area of the stress-strain hysteresis loops at the half of the fatigue life, was plotted against the fatigue life, the data showed greater scattering than the TMF life against the inelastic strain range. A noticeable stress relaxation in the stress-strain hysteresis curve took place at the peak temperatures higher than 700$^{\circ}C$, but all specimens in this study exhibited cyclic hardening behavior with TMF cycles. Recrystallization occurred during the TMF cycle concurrent with the formation of fine subgrains in the recrystallized region, which is considered to cause the cyclic hardening of the steel.

항생제(抗生劑) 내성(耐性) 화농균(化膿菌)의 생육(生育)을 억제(抑制)하는 한약재(韓藥材) 탐색(探索)에 관(關)한 硏究(연구) (A Study on Screening of Oriental Medicines Against Antibiotics-resistant Staphylococcus aureus)

  • 박원영;서운교;정지천
    • 대한한방내과학회지
    • /
    • 제19권2호
    • /
    • pp.300-316
    • /
    • 1998
  • The various oriental herbal medicines, which have usually been used for treatment of reducing fever, purging intense heat and detoxication, were screened to determine the antibacterial activity and the minimal inhibitory concentration against antibiotics-resistant Staphylococcus aureus. The results obtained were as follows: 1. Among the 23 oriental medicines tested, the water-soluble extract of Coptis japonica showed very excellent antibacterial activity against antibiotics-sensitive and -resistant S. aureus. A little activity was found in the extracts of Scutellaria baicalensis, Eriobotrya japonica and Prunus mume against antibiotics-sensitive S. aureus and in that extracts of P. mume, Schizandra chinensis and S. baicalensis against antibiotics-resistant S. aureus. When C japonica was used, the high antibacterial activity was shown against Bacillus subtilis and other extracts showed a little or no antibacterial activity against B. subtilis and E. coli as a control. 2. The highest antibacterial activities against antibiotics-resistant S. aureus were found in the ethanol-soluble extract of C japonica. Other ethanol-soluble extracts of S, baicalensis, S. chinensis and P. mume showed a little activity against both antibiotics-sensitive and antibiotics-resistant S. aureus. 3. Among the medicinal herbs tested, the water- and ethanol extracts of C. japonica showed very excellent antibacterial activity against the pathogenic S. aureus and both Escherichia coli and Bacillus subtilis used as a control. 4. When the water-soluble extracts of C. japonica and S. baicalensis, minimal inhibitory concentrations (MICs) against antibiotics-sensitive S. aureus were $20mg/m{\ell}\;and\;30mg/m{\ell}$, respectively. The MICs of the ethanol-soluble extracts of C. japonica and P. scabriosaefolia were $7.5mg/m{\ell}\;and\;12mg/m{\ell}$, respectively. 5. For the MICs against antibiotics-resistant S. aureus, the water-soluble extracts of C. japonica and P. mume showed $15mg/m{\ell}\;and\;10mg/m{\ell}$, respectively. The MICs of the ethanol-soluble extracts of C. japonica and P. mume were $13mg/m{\ell}\;and\;20mg/m{\ell}$, respectively. As a result, the highest antibacterial activity was found in both water- and ethanol-soluble extracts of C. japonica against antibiotics-resistant S. aureus. And the water- and ethanol-soluble extracts of S. baicalensis, S. chinensis and P. mume showed comparatively high antibacterial activities against both antibiotics-sensitive and -resistant S. aureus.

  • PDF

CO-기 합금의 열처리에 의한 미세조직 및 기계적 특성변화에 관한 연구 (The Effect of Heat Treatment on the Microstructural Evolution and Mechanical Properties of Co-base Materials)

  • 김기엽;정병호;안용식
    • 동력기계공학회지
    • /
    • 제5권2호
    • /
    • pp.63-70
    • /
    • 2001
  • To obtain the optimal condition of heat treatment of wear-resistant alloy, hardness and Charpy V-notch test have been performed with Co-based Stellite No.4, No.6 and Tribaloy 800 alloys, following by heat treatment at the various conditions. Heat treatment at $1250^{\circ}C$ for 1 hours caused the as-casted Tribaloy 800 with FCC crystal structure to transform to HCP structure and lamellar eutectic structure was disappeared, which did not influence on the hardness. Aging at $800^{\circ}C$ for 20 hours, following by $1250^{\circ}C$ for 2 hours heat treatment has enhanced hardness significantly, which is due to the precipitation of large amounts of Laves-phase. The hardness of Stellite alloys was increased by the aging at $800^{\circ}C$ to 5 hours, and was nearly constant by the aging over 5 hours. The toughness of Stellite alloys was a few influenced by the aging treatment.

  • PDF