• Title/Summary/Keyword: AL072

Search Result 22, Processing Time 0.024 seconds

Effect of AL072, a Novel Anti-Legionella Antibiotic, on Growth and Cell Morphology of Legionella pneumophila

  • Kang, Byeong-Cheol;Park, Jae-Hak;Lee, Yong-Soon;Suh, Jung-Woo;Chang, Jun-Hwan;Lee, Chul-Hoon
    • Journal of Microbiology and Biotechnology
    • /
    • v.9 no.3
    • /
    • pp.371-375
    • /
    • 1999
  • AL072 is a potent anti-Legionella antibiotic produced by Streptomyces strain AL91. The minimum inhibitory concentration (MIC) of AL072 against Legionella pneumophila was 0.2$\mu$g/ml. Bacterial growth was rapidly inhibited at the dose range between the MIC and 20 times of the MIC when the antibiotic was added at the mid-exponential phase. Ultrastructural changes in L. pneumophila were observed upon treatment with AL072. Under electron microscopical observation, the organisms treated with AL072 exhibited characteristic morphological changes in the cellular outer coat. Also irregular morphological changes, such as the formation of filamentous materials in the cytoplasm, an increase in the size and number of cytoplasmic vacuoles, the extruding of cytoplasmic contents, the formation of spheroplast and ghost cells, and blebbings in the cell wall were observed. Furthermore, immunoelectron microscopical observation of the group treated with the MIC showed that the immune complex attached mainly to the cell wall. The results of these experiments indicate that AL072, like the inhibitors of cell wall synthesis, act selectively on the cell wall of L. pneumophila.

  • PDF

Optimal Parameter Design for Al/SiC Composites using Design of Experiments (실험계획법에 의한 Al/SiC 복합재료의 최적공정 설계)

  • Lee, K.J.;Kim, K.T.;Kim, Y.S.
    • Journal of Power System Engineering
    • /
    • v.15 no.5
    • /
    • pp.72-76
    • /
    • 2011
  • In this work, the parameter optimization for thermal-sprayed Al/SiC composites have been designed by $L_9(3^4)$ orthogonal array and analysis of variance(ANOVA). Al/SiC composites were fabricated by flame spray process on steel substrate. The hardness of composites were measured using micro-vickers hardness tester, and these results were analyzed by ANOVA. The ANOVA results showed that the oxygen gas flow, powder feed rate and spray distance affect on the hardness of the Al/SiC composites. From the ANOVA results, the optimal combination of the flame spray parameters could be extracted. It was considered that experimental design using orthogonal array and ANOVA was efficient to determine optimal parameter of thermal-sprayed Al/SiC composites.

High-temperature corrosion properties of Al2O3 + (Fe2O3, Al, Cr and Si) mixed sintering materials (Al2O3 + (Fe2O3, Al, Cr and Si) 소결 복합재료의 고온 부식 특성)

  • Kim, Min-Jeong;Won, Seong-Bin;Bong, Seong-Jun;Lee, Dong-Bok;Son, In-Jin
    • Proceedings of the Korean Institute of Surface Engineering Conference
    • /
    • 2012.05a
    • /
    • pp.170-171
    • /
    • 2012
  • $Fe_2O_3$, Al, Cr과 Si 분말을 고 에너지 볼 밀링해서 나노분말을 제조한 후 고주파유도 가열 활성 연소합성 장치로 1분 이내의 짧은 시간에 합성 및 소결한 $Al_2O_3+4.65(Fe_{0.43}Cr_{0.17}Al_{0.323}Si_{0.077})$, $Al_2O_3$ + 5.33 ($Fe_{0.375}Cr_{0.11}Al_{0.3}Si_{0.075}$), $Al_2O_3$ + 6.15 ($Fe_{0.325}Cr_{0.155}Al_{0.448}Si_{0.072}$), $Al_2O_3$ + 3.3 ($Fe_{0.6}Cr_{0.3}Al_{0.6}$) 소결체 시편을 $700^{\circ}C$의 온도에서 100시간 동안 공기 중에서 산화 및 $N_2-H_20-H_2S$ 혼합 가스 내에서 황화 부식을 실시하였다. 그 결과 산화 및 황화 부식 후에 ${\alpha}-Al_2O_3$가 표면에 생성되어 보호 피막으로 작용하여 우수한 내식성을 보였다.

  • PDF

Welding Characteristics of Aluminized Steel Sheet by Nd:YAG Laser(II) - Behavior of Al element in the weld - (Nd:YAG 레이저를 이용한 알루미늄도금강판의 용접성(II) - 용접부내 알루미늄의 거동 -)

  • Kim, Jong-Do;Lee, Jung-Han;Kim, Ki-Chol
    • Journal of Welding and Joining
    • /
    • v.25 no.4
    • /
    • pp.72-78
    • /
    • 2007
  • Aluminized steel sheet is a material with excellent heat resistance, thermal reflection and corrosion resistance. It has wide applications, owing to its low cost and excellent performance, in the petrochemical industry, electric power and other energy conversion systems, etc and has attracted the attention of many investigators. But the welding of aluminized steel sheet has a problem of decreasing tensile-shear strength, caused by mixed Al in the weld. This study investigated behavior of Al and its structural properties to resolve this problem. Several analysis equipment(SEM, EDX, EPMA) were used to investigate Al element in the weld. Also microhardness tester and TEM equipment were used to find the intermetallic compound. As a result of this study, Al-rich zones existed in the weld and Fe-Al intermetallic compounds were found in these zones. At the same time, the weldability of aluminized stainless steel sheet was investigated and compared with that of aluminized steel sheet. Although there is a difference between the base metal of the low carbon steel and stainless steel, it is interpreted that a behavior of Al element in the weld is similar.

A Study on Acoustic Signal Characterization for Al and Steel Machining by Audio Deep Learning (오디오 딥러닝을 활용한 Al, Steel 소재의 절삭 깊이에 따른 오디오 판별)

  • Kim, Tae-won;Lee, Young Min;Choi, Hae-Woon
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.20 no.7
    • /
    • pp.72-79
    • /
    • 2021
  • This study reports on the experiment of using deep learning algorithms to determine the machining process of aluminium and steel. A face cutting milling tool was used for machining and the cutting speed was set between 3 and 4 mm/s. Both materials were machined with a depth to 0.5mm and 1.0mm. To demonstrate the developed deep learning algorithm, simulation experiments were performed using the VGGish algorithm in MATLAB toobox. Downcutting was used to cut aluminum and steel as a machining process for high quality and precise learning. As a result of learning algorithms using audio data, 61%-99% accuracy was obtained in four categories: Al 0.5mm, Al 1.0mm, Steel 0.5mm and Steel 1.0mm. Audio discrimination using deep learning is derived as a probabilistic result.

Strain-free AlGaN/GaN Nanowires for UV Sensor Applications (Strain-free AlGaN/GaN 자외선 센서용 나노선 소자 연구)

  • Ahn, Jaehui;Kim, Jihyun
    • Korean Chemical Engineering Research
    • /
    • v.50 no.1
    • /
    • pp.72-75
    • /
    • 2012
  • In our experiments, strain-free nanowires(NWs) were dispersed on to the substrate, followed by e-beam lithography(EBL) to fabricate single nanowire ultraviolet(UV) sensor devices. Focused-ion beam(FIB), micro-Raman spectroscopy and photoluminescence were employed to characterize the structural and optical properties of AlGaN/GaN NWs. Also, I-V characteristics were obtained under both dark condition and UV lamp to demonstrate AlGaN/GaN NW-based UV sensors. The conductance of a single AlGaN/GaN UV sensor was 9.0 ${\mu}S$(under dark condition) and 9.5 ${\mu}S$ (under UV lamp), respectively. The currents were enhanced by excess carriers under UV lamp. Fast saturation and decay time were demonstrated by the cycled processes between UV lamp and dark condition. Therefore, we believe that AlGaN/GaN NWs have a great potential for UV sensor applications.

Fabrication and dielectric properties of $LaAlO_3-BaZrO_3$ perovskites ($LaAlO_3-BaZrO_3$계 perovskites의 제조 및 유전특성)

  • Lee, So-Hee;Kim, Shin;Shin, Hyun-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2007.06a
    • /
    • pp.325-325
    • /
    • 2007
  • The perovskites in the $LaAlO_3-BaZrO_3$ system (i.e., $(1-x)LaAlO_3-xBaZrO_3$ were fabricated by a solid state reaction and their dielectric properties were investigated. For the compositions of x=0.1~0.9, the mixture of $LaAlO_3$ with a rhombohedral structure and $BaZrO_3$ with a cubic was observed when the sintering was conducted at $1500^{\circ}C$, indicating that the solubility of constituent elements was very low and a narrow solid solution region might exist. The large difference of ionic radii between $La^{3+}$ ion (0.136nm, C.N.=12) and $Ba^{2+}$ ion (0.161nm) or $Al^{3+}$ ion (0.0535nm, C.N.=6) and $Zr^{4+}$ ion (0.072nm) might hinder the mutual substitution. Within the compositions of x=0~0.7, the dielectric constant of the mixture increased with the amount of $BaZrO_3$, i.e., x value, which was in good agreement with the logarithmic mixing rule (In $_{r,i}={\Sigma}v_iln\;_{r,i}$). The increase in $BaZrO_3$ doping decreased $Q{\times}f$ value significantly due to the low $Q{\times}f$ value of $BaZrO_3$ itself, a poor microstructure of the mixture with an increased grain boundary area per volume, and defects in the cation and oxygen sub-lattices which were respectively caused by the evaporation of barium during the sintering process and the substitution of Ba on La-site or Al on Zr-site.

  • PDF

Performance Analysis of the Nozzleless Booster (무노즐 부스터 성능해석)

  • Kim, Kyungmoo;Khil, Taeock;Ryu, Taeha
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.21 no.2
    • /
    • pp.72-82
    • /
    • 2017
  • Nozzleless booster is one of the applicable components for integral rocket ramjet (IRR). In order to predict nozzleless solid booster performance, the simplified theoretical analysis was applied for L/D=5, 6, 7, 9, 11, and 13. Al-HTPB and Zr-HTPB propellant with a high metal content were used to increase the hardness because of the combustion gas flow effect. It was found that the trends between the simplified theoretical analysis and experiments were similar.

The Effect of Radiative Heat Flux on Dynamic Extinction in Metalized Solid Propellants (복사열전달이 고체 추진제의 동적소화에 미치는 영향)

  • Jeong, Ho Geol;Lee, Chang Jin
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.31 no.2
    • /
    • pp.72-79
    • /
    • 2003
  • A numerical calculation was conducted to estimate and to elucidate the role of the radiative heat flux from metal particles(Al, $Al_2O_3$) on the dynamic extinction of solid propellant rocket where the rapid depressurization took place. Anon-linear flame modeling implemented by the residence time modeling for metalized propellant was adopted to evaluate conductive heat flux to the propellant surface. The radiative heat feed back was calculated with the aid of a modified comvustion-flow model as well. The calculation results with the propellant of AP:Al:CTPB=76:10:14 had revealed that the radiative heat flux is approximately 5~6% of total flux at the critical depressurization rate regardless of chamber geometry (open or confined chamber). It was also found that the dynamic extinction in open geometry could be predicted at the depressurization rate about 45% larger with radiative heat feedback than without radiation. Thus, it should be claimed that even a small amount of radiative flux 5~6% could produce a big error in predicting the critical depressurization rate of the metalized propellant combustion.

Preparation and Characterization of Screen-printed Lead Zirconate Titanate Thick Films

  • Lee Sung-Gap
    • Transactions on Electrical and Electronic Materials
    • /
    • v.7 no.2
    • /
    • pp.72-75
    • /
    • 2006
  • Ferroelectric PZT heterolayered thick films were fabricated by the alkoxide-based sol-gel method. PZT(Zr/Ti=60/40) paste was made and alternately screen-printed on the $Al_2O_3$ substrates. We have introduced a press-treatment to obtain a good densification of screen printed films. The porosity of the thick films was decreased with increasing the applied pressure and the thick films pressed at $0.6ton/cm^2$ showed the dense microstructure and thickness of about $76{\mu}m$. The relative dielectric constant increased with increasing the applied pressure. The remanent polarization and coercive field increased with increasing applied pressure and the values for the PZT thick films pressed at $0.6ton/cm^2$ were $16.6{\mu}C/cm^2$, 76.9 kV/cm, respectively.