• 센서학회지
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• 제8권5호
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• pp.421-426
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• 1999

본 논문에서는 반절연성 GaAs(semi-insulating GaAs) 기판위에 $Al_2O_3$ 절연막이 게이트 절연막으로 이용된 공핍형모드 p-채널 GaAs MOSFET (depletion mode p-channel GaAs MOSFET)를 제조하였다. 반절연성 GaAs 기판위에 $1\;{\mu}m$의 GaAs 버퍼층(buffer layer), $4000\;{\AA}$의 p형 GaAs 에피층(epi-layer), $500\;{\AA}$의 AlAs층, 그리고 $50\;{\AA}$의 캡층(cap layer)을 차례로 성장시키고 습식열산화시켰으며, 이를 통하여 AlAs층은 완전히 $Al_2O_3$층으로 산화되었다. 제조된 MOSFET의 I-V, $g_m$, breakdown특성 측정을 통하여 AlAs/GaAs epilayer/S I GaAs 구조의 습식열산화는 공핍형 모드 p-채널 GaAs MOSFET를 구현하기에 적합함을 알 수 있다.

• 한국재료학회지
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• 제22권6호
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• pp.316-320
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• 2012

$Co_3O_4$, $Al_2O_3$ and $Co_3O_4$/$Al_2O_3$ mesoporous powders were prepared by a sol-gel method with starting matierals of aluminum isopropoxide and cobalt (II) nitrate. A P123 template is employed as an active organic additive for improving the specific surface area of the mixed oxide by forming surfactant micelles. A transition metal cobalt oxide supported on alumina with and without P123 was tested to find the most active and selective conditions as a heterogeneous catalyst in the reaction of styrene epoxidation. A bBlock copolymer-P123 template was added to the staring materials to control physical and chemical properties. The properties of $Co_3O_4$/$Al_2O_3$ powder with and without P123 were characterized using an X-ray diffractometer (XRD), a Field-Emission Scanning Electron Microscope (FE-SEM), a Bruner-Emmertt-Teller (BET) surface analyzer, and $^{27}Al$ MAS NMR spectroscopy. Powders with and without P123 were compared in catalytic tests. The catalytic activity and selectivity were monitored by GC/MS, $^1H$, and $^{13}C$-NMR spectroscopy. The performance for the reaction of epoxidation of styrene was observed to be in the following order: [$Co_3O_4$/$Al_2O_3$ with P123-1173 K > $Co_3O_4$/$Al_2O_3$ with P123-973 K > $Co_3O_4$-973 K>$Co_3O_4$/$Al_2O_3$-973 K > $Co_3O_4$/$Al_2O_3$ with P123-1473 K > $Al_2O_3$-973 K]. The existence of ${\gamma}$-alumina and the nature of the surface morphology are related to catalytic activity.

• 한국식품영양과학회지
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• 제13권2호
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• pp.193-204
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• 1984

Zymolyase 조효소로부터 분리, 정제되었고, 효모세포벽 용해 촉진물질로 밝혀진 바 있는 Arthrobacter luteus로부터 유래한 염기성 protease(AL-protease)의 효소학적 성질 및 활성 아미노산 잔기를 검색한 결과는 다음과 같다. 1. AL-pretense는 저해제 DFP 및 PMSF에 의해서 그 Protease 활성 및 용해 촉진활성이 동시에 완전히 소멸 되었으며, 그 저해 반응속도는 chymotrypsin에 대한 것에 비하여 대단히 완만하였다. 1.반응에서 AL-protease와 DFP의 결합 mole비는 1:1로 추정 되었다. 2. 정제된 AL-protease의 동결건조품 중에는 종래효모세포벽 용해반응에 관여하는 것으로 알려진 yeast phosphomannase를 비롯한 다당류 가수분해효소들의 활성은 그 어느 것도 인정되지 않았다. 3. AL-protease의 casein에 대한 최적 pH 및 최적 온도는 pH 10.5와 $65^{\circ}C$이었고, 그 활성은 pH 5${\sim}$11 사이와 $65^{\circ}C$이하에서 안정하였다. 또한, AL-Protease의 활성에 미치는 여러가지 금속이온의 영향은 인정되지 않았다. 4. [$^{32}P$]-DFP에 의하여 화학수식된 [$^{32}P$]-DIP-AL-protease에 대한 활성부위의 아미노산 잔기를 검색, 동정하기 위하여 조제용 PAG-전기영동, SDS-PAG-전기영동, Dowex 이온교환 크로마토그래피 및 고압 여지 전기영동을 실시하였고, 그 결과, AL-protease는 활성 부위에 1분자당 1 mole의 serine 잔기를 가지는 염기성 protease로 밝혀졌다.

• 폴리머
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• 제29권2호
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• pp.122-126
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• 2005

Al-MCM-41의 제조방법이 선형 저밀도 폴리에틸렌(LLDPE)의 촉매 분해 활성에 어떠한 영향을 주는지 조사하였다 이를 위해 Al-MCM41은 직접 합성법(Al-MCM41-D)과 후처리법(Al-MCM-41-P)의 두 가지 방법으로 제조되었으며, XRD, BET, $NH_3\;TPD,\;^{27}Al$ MAS NMR 등을 이용하여 이들 촉매 특성을 규명하였다. TGA 동역학 방법을 사용하여 Al-MCM-41-D와 Al-MCM-41-P의 LLDPE촉매 분해 활성화 에너지를 구한 결과 각각 197.54, 174.26 kJ/mol로 나타났다. 이처럼 시-MCM-41-P가 시-MCM-41-D보다 촉매 활성이 높은 이유는 접근 가능한 산점수가 훨씬 많고 상대적으로 기공 크기도 작은 것에 기인한 것으로 여겨진다.

• Parasites, Hosts and Diseases
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• 제51권1호
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• pp.75-84
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• 2013

Cutaneous leishmaniasis (CL) is an endemic parasitic infection in the Mediterranean region, including Libya and its Al-jabal Al-gharbi province. We aimed at studying the occupational relevance as well as other epidemiological aspects of CL. We investigated 140 CL cases who attended at Gharyan outpatient polyclinic during a period of 6 months in 2009. CL infection was clinically diagnosed and confirmed by demonstration of Leishmania parasites on smears from lesions. Our findings showed that males were more affected than females (P=0.04), and people above 10-years were more affected than younger ones (P=0.0001). A significant percent of CL cases belonged to Al-Kawasem subprovince (P=0.0001). Farm-related activities were the most frequent occupations among CL cases (P=0.04). In addition to farm workers, housewives and students are at risk groups since they are engaged at farm activities. Moreover, those who have occupations that require staying outdoors for a part of night, e.g., policemen, are also at risk. Compared to children, adult CL patients had multiple lesions (P=0.001) that were more prevalent in their upper and lower extremities than the face (P=0.0001). We conclude that CL is a major health problem in Al-jabal Al-gharbi province of Libya. The presence of rodents and sandflies makes it a suitable environment for Leishmania to spread in an endemic epidemiological pattern. Being engaged in farming activities or outdoor occupations increases the risk of infection. Various clinical patterns of CL suggest the presence of more than 1 species of Leishmania at Al-jabal Al-gharbi province. We propose that the 2 species responsible for CL in this area are L. major and L. tropica. Further investigations to identify the leishmanial species responsible for CL at Al-jabal Al-gharbi together with adoption of preventive and control programs are needed.

• Journal of Magnetics
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• 제20권4호
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• pp.331-335
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• 2015

The ferromagnetic and electronic structure for the $Al_xGa_{1-x}P$ and Mn-doped $AlGaP_2$ was studied by using the self-consistent full-potential linear muffin-tin orbital method. The lattice parameters of un-doped $Al_xGa_{1-x}P$ (x = 0.25, 0.5, and 0.75) were optimized. The band-structure and the density of states of Mn-doped $AlGaP_2$ with or without the vacancy were investigated in detail. The P-3p states at the Fermi level dominate rather than the other states. Thus a strong interaction between the Mn-3d and P-3p states is formed. The ferromagnetic ordering of dopant Mn with high magnetic moment is induced due to the (Mn-3d)-(P-3p)-(Mn-3d) hybridization, which is attributed by the partially filled P-3p bands. The holes are mediated with keeping their 3d-characters, therefore the ferromagnetic state is stabilized by this double-exchange mechanism.

• 한국분말재료학회지
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• 제4권1호
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• pp.26-41
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• 1997

The powder metallurgy (P/M) processed 2009 and 2124 Al composites reinforced with SiC particulates were studied by focusing on the effect of consolidation temperature on the microstructural and mechanical Properties. The mechanical properties such as tensile properties and microhardness of the second phases were analysed in relation to the microstructures observed by a SEM and an optical microscope. The in situ fracture process study using SEM showed that the grain refinement and the removal of manganese-containing particles often observed in the 2124 Al-${SiC}_{p}$ composites were important for the improvement of the mechanical properties. This study offers an optimum consolidation temperature for the control of the manganese-containing particles in the 2124 Al-${SiC}_{p}$ composites that yields mechanical properties higher than those of the 2009 Al-${SiC}_{p}$ composites.

• 대한화학회지
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• 제6권1호
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• pp.29-31
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• 1962

電壓條件 永動時間 및 支持電解質溶液의 pH가 Al ion의 paper electrophoresis에 미치는 影響을 closed horizontal type의 泳動裝置를 써서 Michaelis buffer soln.으로 飽和시킨 paper strip에서 實驗的으로 檢討하였다. 그 結果 Al ion에 가장 適合한 pH, 電壓 및 泳動時間을 決定하였으며 pH=2.38에서 Al ion의 mobility는 $(1.004{\pm}0.0020){\times}10^{-4}\;cm^2\;sec^{-1}\;volt^{-1},\;Al(NO_3)_3\;soln.$의 isoelectric point는 pH=3.23 임을 알았다.

• 열처리공학회지
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• 제15권2호
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• pp.76-81
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• 2002

The melt-spun amorphous $Fe_{77-X}P_{13}C_4B_4Al_2Mo_X$(x=4~10) and $Fe_{82-X}P_XC_4B_4Al_2Mo_8$(x=9~15) alloys were found to exhibit a large supercooled liquid region(${\Delta}T_x$) exceeding 40 K before crystallization. The largest ${\Delta}T_x$ for the glassy alloys containing Mo reaches as large as 65 K for the $Fe_{69}P_{13}C_4B_4Al_2Mo_8$ alloy. The corrosion behavior of the amorphous $Fe_{77-X}P_{13}C_4B_4Al_2Mo_X$(x=4~15) and $Fe_(82-X)P_XC_4B_4Al_2Mo_8$ (x=9~17) alloys were examined by electrochemical measurements in 9M $H_2SO_4$ solution at 303 K. The addition of Mo(or P) for replacing some portion of Fe is effective in improving the corrosion resistance of the investigated Fe-based glassy alloys. They are spontaneously passivated and have a wide passive region with low passive current density.

• 반도체디스플레이기술학회지
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• 제19권3호
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• pp.49-54
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• 2020

We studied the electronic and magnetic properties for the Mn-doped chalcopyrite (CH) AlAs, GaAs, and AlGaAs₂ semiconductor by using the first-principles calculations. The chalcopyrite AlGaP₂, AlGaAsP, and AlGaAs₂ compounds have a semiconductor characters with a small band-gap. The interaction between Mn-3d and As-4p states at the Fermi level dominate rather than the other states. The ferromagnetic ordering of dopant Mn with high magnetic moment is induced due to the Mn(3d)-As(4p) strong coupling, which is attributed by the partially filled As-4p bands. The holes are mediated with keeping their 3d-electrons, therefore the ferromagnetic state is stabilized by this double-exchange mechanism. We noted that the ferromagnetic state with high magnetic moment is originated from the hybridized As(4p)-Mn(3d)-As(4p) interaction mediated by the holes-carrier.