• Title/Summary/Keyword: Al concentration

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Effects of Al Doping Concentration on the Microstructure and Physical Properties of ZnO Thin Films Deposited by Cosputtering (Cosputtering법으로 증착한 ZnO박막의 Al도핑농도가 미세구조 및 물리적 특성에 끼치는 효과)

  • Yim, Keun-Bin;Lee, Chong-Mu
    • Korean Journal of Materials Research
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    • v.15 no.9
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    • pp.604-607
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    • 2005
  • Dependence of the crystallinity, surface roughness, carrier concentration, carrier mobility, electrical resistivity and transmittance of Al-doped ZnO films deposited on glass substrates by RF-magnetron sputtering on effects of the ratio of the RF power for AlZnO to that for ZnO (R) have been investigated. X-ray diffraction spectra show strong preferred orientation along the c-axis. The full width at half maximum (FWHM) of the ZnO (002) peak decreases slightly as R increases in the range of R<1.0, whereas it increases substantially in the range of R>1.0. Scanning electron micrographs (SEM) show that the ZnO film surface becomes coarse as R increases. The carrier concentration and the carrier mobility in the ZnO thin film are maximal for R=1.5 and 1.0, respectively. The electrical resistivity is minimal for R=1.0 The transmittance of the ZnO:Al film tends to increase, but to decrease slightly in the range of R>0.5. It may be concluded that the optimum R value is 1.0, considering all these analysis results. The cause of the changes in the structure and physical properties of ZnO thin films with R are also discussed.

Cell separation from high density culture broths of Alcaligenes eutrophus by using Al-based coagulants (Alcaligens eutrohus 고농도 배양액으로부터 알루미늄(Al)계 응집제를 이용한 세포분리)

  • 조경숙;류희욱;정현우;곽종운;장용근
    • KSBB Journal
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    • v.13 no.3
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    • pp.272-278
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    • 1998
  • Cell recovery from high cell density broths of Alcaligenes eutrophus by pretreatment with aluminum-based coagulants such as aluminum sulfate, polyaluminum hydrooxide chloride silicate (PACS), and polyaluminum hydrooxide chloride (Hi-PAX) was carried out. Cells coagulated with coagulants could be successfully recovered above 95-99% by centrifugation or filtration. The optimum initial pH of fermentation broths for cell recovery was in the range of 10 to 12. Optimum coagulants dosage for cell recovery increased with increasing of cell concentrations (21-160 g/L). The optimum coagulant dosages to recover cells with more than 95% cell recovery by centrifugation for the cell concentrations ranged 21-160 g/L were as follows: aluminum sulfate, 416-1708 mg Al/L; PACS, 211-826 mg Al/L; Hi-PAX, 320-960 mg Al/L. At optimum conditions for the coagulation of cells, centrifugal forces for 95% of cell recovery were dependent on the cell concentration. The centrifugal forces at 82 g/L and 160 g/L of cell concentration were only 45${\times}$g and 1600${\times}$g, respectively.

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Magnetic Properties of Cu-doped AlN Semiconductor (AlN 반도체와 Cu의 도핑 농도에 대한 자성)

  • Kang, Byung-Sub;Lee, Haeng-Ki
    • Journal of the Semiconductor & Display Technology
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    • v.9 no.3
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    • pp.1-4
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    • 2010
  • First-principles calculations based on spin density functional theory are performed to study the spin-resolved electronic properties of AlN doped with a Cu concentration of 6.25%-18.75%. The ferromagnetic state is more energetically favorable state than the antiferromagnetic state or the nonmagnetic state. For $Al_{0.9375}Cu_{0.0625}N$, a global magnetic moment of 1.26 mB per supercell, with a localized magnetic moment of 0.75 $m_B$ per Cu atom is found. The magnetic moment is reduced due to an increase in the number of Cu atoms occupying adjacent cation lattice position. For $Al_{0.8125}Cu_{0.1875}N$, the magnetism of the supercell disappears by the interaction of the neighboring Cu atoms. The nonmagnetic to ferromagnetic phase transition is found to occur at this Cu concentration. The range of concentrations that are spin-polarized should be restricted within very narrow.

Effects of Aluminium on Vitellogenin and Its mRNA Induction by Estradiol-17$\beta$ in the Primary Culture of Hepatocytes in the Rainbow Trout Oncorhynchus mykiss

  • Hwang, Un-Gl;Park, Jin-Il;Shim, Jung-Min;Jung, Chang-Soo;Park, Sung-Yoon
    • Proceedings of the Korean Environmental Sciences Society Conference
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    • 2003.11a
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    • pp.159-164
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    • 2003
  • Effects of Al on vitellogenin (VTG) and VTG mRNA induction by estradiol-17 $\beta$($E_2$) were examined in primary hepatocyte culture of rainbow trout. Hepatocytes were precultured for 2 days and then E2 ($2{\times}10^{-6}$M) and Al ($10^{-6}-10^{-4}$M) were simultaneously added to the incubation medium. Hepatocytes were cultured for 5 more days. Media and hepatocytes were then analyzed by SDS-PAGE and Northern blotting for VTG and VTG mRNA, respectively. These metal had no appreciable effect on the viability of hepatocytes in culture. However, Al interfered with VTG production and VTG mRNA expression. Al reduced VTG production in a concentration-dependent way and a significant reduction accurred at Al concentrations greater than $5{\times}10^{-5}$M. VTG mRNA expression also decreased with a negative correlation with Al concentration (r=-0.98). These results suggest that Al inhibit VTG production at the transcriptional level to reduce VTG mRNA expression.

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Effects of polymeric Al and hydrolysis products of PAC at different pH on performance of nanofiltration with PAC coagulation pretreatment (PAC 전처리 시 수소이온 농도에 따라 발생 가능한 알루미늄 종에 의한 나노여과막 성능 연구)

  • Choi, Yang-Hun;Kweon, Ji-Hyang
    • Journal of Korean Society of Water and Wastewater
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    • v.24 no.1
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    • pp.15-24
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    • 2010
  • Coagulation can be used for pretreatment of NF membrane filtration. Foulants such as organic matter and particulate can be removed effectively with the process while high flux recovery is maintained. Recently various types of polyaluminium coagulants including polyaluminium chloride(PAC) are commercially available for water treatment. This study examines effects of polymeric Al and hydrolysis products of PAC on nanofiltration membrane performance. Dominant hydrolysis products were polymeric Al, $Al(OH)_3$, and ${Al(OH)_4}^{-1}$ at acidic, neutral, and alkaline pH conditions, respectively. Under acidic pH condition, flux decline was increased with increasing PAC concentrations, possibly due to polymeric Al adsorption on membrane pore and/or surfaces. For neutral and alkaline pH conditions, little flux decline was observed with increasing PAC concentrations except the highest ${Al(OH)_4}^{-1}$ concentration, with which rapid flux decline was shown. Removal of ionic matters was also varied with pH conditions in this study. Especially, conductivity removal was substantially low and $Ca^{2+}$ concentration in the permeate was quite high at neutral pH condition.

Wear Characteristics of Lubricant with Nano-diamond Particles on Al-6061 Aluminum Alloy (나노 다이아몬드 입자를 첨가한 엔진 오일의 알루미늄 6061 합금에 대한 마모 특성)

  • Hwang, Sung-Wan
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.12
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    • pp.16-23
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    • 2021
  • Pin-to-disc wear testing experiments were conducted to investigate the wear characteristics of commercial oil (5W-40) with nano-diamond particles. The upper specimen was a SUJ-2 high-carbon chromium steel ball with a diameter of 4 mm, and the lower specimen was made of the Al-6061 alloy. The applied load was 5 N, and the sliding speed was 0.25 m/s. The wear tests were conducted at a sliding distance of 500 m. The friction coefficients and wear rates of the Al-6061 specimens were tested using commercial oil with different nano-diamond concentrations ranging from 0 to 0.02 wt.%. The addition of nano-diamond particles to commercial oil reduced both the wear rate and coefficient of friction of the Al-6061 alloy. The use of nano-diamond particles as a solid additive in oil lubricants was found to improve the tribological behavior of the Al-6061 alloy. For the Al-6061 alloy, the optimal concentration was found to be 0.005 wt.% in view of the friction coefficient and wear rate. Further investigation is needed to determine the optimal concentration of nano-diamond particles for various loadings, sliding speeds, oil temperatures, and sliding distances.

Beverage Development using Abeliophyllum distichum Leaf Extract and Its Physicochemical Properties (미선나무 잎 추출물을 이용한 음료 개발 및 이화학적 특성)

  • Ho-Jin Lee;Sun-Young Kwon;Pil-Mun Jung;Eun-Ah Kim;Kyung-Haeng Lee
    • The Korean Journal of Food And Nutrition
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    • v.36 no.2
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    • pp.122-128
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    • 2023
  • A beverage was developed using the Abeliophyllum distichum leaf (AL). The beverage was prepared by adding it to apple juice by concentration, and physicochemical quality, antioxidant activities, and sensory evaluation were measured. Soluble solid and reducing sugar content of the control were 12.57 °Brix and 11.40%, respectively, and there was no difference from the group with addition of the AL extract. However, pH was slightly increased upon addition of AL extract. Lightness and yellowness increased when AL extract was added. Verbascoside content was not detected in the control, but it increased as the concentration of AL extract increased. The contents of ascorbic acid and flavonoids were 5.38 and 20.42 mg%, respectively, and there was no significant difference between the groups. However, the content of polyphenols increased as the concentration of the AL extract increased. DPPH radical and metal ion scavenging activity were increased by addition of the AL extract, but there was no difference in the ABTS radical scavenging activity. As a result of the sensory evaluation, there was no difference from the control even wihen the AL extract was added; thus, it was considered that there was no problem with the degree of acceptability when added within about 300 ppm.

Properties of Al-doped ZnO Transparent Conducting Oxide Films Deposited with Ar Flow Rate by RF Magnetron Sputtering (RF 마그네트론 스퍼터링법으로 증착된 Al 도핑된 ZnO 투명 전도 산화막의 Ar 유량에 따른 특성)

  • Yi, I.H.;Kim, D.K.;Kim, H.B.
    • Journal of the Korean Vacuum Society
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    • v.19 no.3
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    • pp.206-210
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    • 2010
  • Al-doped ZnO thin films were deposited with various Ar flow rate by RF magnetron sputtering, and theire properties were studied. A high-quality thin film was obtained by controlling the Ar flow rate, and the influence of the Ar flow rate on the Al-doped ZnO thin film was confirmed. In all Al-doped ZnO thin films, light transmittance had above 80%. Through Hall measurement and X-ray photoelectron spectrometer, the sample of 60 sccm, which had the lowest resistivity, showed the lower Al concentration. This result was attributed to oxygen vacancy rather than Al concentration.

Effects of Chloride Concentration and Applied Current Density on Stray Current Corrosion Characteristics of 6061-T6 Al Alloy for Electric Vehicle Battery Housing (전기자동차 배터리 하우징용 6061-T6 알루미늄합금의 전식 특성에 미치는 염화물농도 및 인가전류밀도의 영향)

  • Shin, Dong-Ho;Kim, Seong-Jong
    • Corrosion Science and Technology
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    • v.21 no.5
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    • pp.348-359
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    • 2022
  • Interest in electric vehicle is on the rise due to global eco-friendly policies. To improve the efficiency of electric vehicles, it is essential to reduce weights of components. Since electric vehicles have various electronic equipment, the research on stray current corrosion is required. In this research, a galvanostatic corrosion experiment was performed on 6061-T6 Al alloy for electric vehicle battery housing using chloride concentration and applied current density as variables in a solution simulating an acid rain environment. As a result of the experiment, when chloride concentration and applied current density were increased, corrosion damage became larger. In particular, pitting damage was dominant at an applied current density of 0.1 mA/cm2. Pitting damage over the entire surface was found at a current density of 1.0 mA/cm2. In conclusion, chloride concentration had a relatively large effect on localized corrosion. The applied current density had a great effect on uniform corrosion. However, in the case of applied current density, localized corrosion was also greatly affected by interaction with chloride.

Characteristics of Al 2024 Conflat Flange Gaskets (Al 2024를 이용한 Conflat Flange Gasket의 특성)

  • 이철로;박재홍;홍승수;임재영;신용현;정광화
    • Journal of the Korean Vacuum Society
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    • v.1 no.2
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    • pp.237-243
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    • 1992
  • Two gaskets of Al 2024-T4 and annealed al 2024-T4 were made. We had acquired 2 $\times$ 10-12torr in a chamber using them. Microstructures, hardness and stress concentration of the gaskets were examined before and after baking. Knife edge damages such as decrease of edge height(H) and increase of edge angle() were found on knife edges when the Al 2024-T4 gasket was used. But no damage was found with the annealed Al 2024 gasket.

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