• Title/Summary/Keyword: Elevated Temperature Structure

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A Recurring Eddy off the Korean Northest Coast Captured on Satellite Ocean Color and Sea Surface Temperature Imagery (위성의 해색 영상과 해수면온도 영상을 활용한 재발생 와동류에 관한 연구)

  • ;B.G.Mitchell
    • Korean Journal of Remote Sensing
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    • v.15 no.2
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    • pp.175-181
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    • 1999
  • A recurring eddy which located at the terminal end of the Korean East Warm Current was captured on ocean color and sea surface temperature imagery from satellite in spring and autumn. During late April, 1997 thermal infrared imagery from the NOAA AVHRR sensor and ocean color data from the Japanese ADEOS-I OCTS sensor, revealed this feature. The cold core had elevated chlorophyll concentrations, based on OCTS estimates, of greater than 3 mg/m$^3$ while the warmer surrounding waters had chlorophyll concentrations of 1 mg/m$^3$ or less. The elevated cholophyll accociated with this eddy has not been previously described. The eddy is also evident in SST images from autumn, but the SST in the core is warmer than in spring, and the warm jet flowing to the west of the eddy is also warmer is autumn compared to spring. A reccurring eddy and the high chlorophyll_a concentration area which surround around the eddy show on NOAA and SeaWiFS images in March 2, 1998. The eddy forms at the northern extent of the Korean East Warm Current as those waters collide with the cold, south-flowing Liman Current over a topographic shelf about 1500 m deep. This region of the eddy formation appears to have a strong connection with the dynamics of the western part of the polar front eddy field that dominates surface mesoscale structure in the central East (Japan) Sea. Interaction of the eddy with ARGOW tracked drifters, and evidence for its persistence are discussed.

Physiological Responses and Fruit Quality Changes of 'Fuji' Apple under the High Night Temperature (야간 고온에 의한 사과 후지 품종의 생리반응 및 과실품질 변화)

  • Ryu, Suhyun;Kwon, YongHee;Do, Kyeong Ran;Han, Jeom Hwa;Han, Hyun Hee;Lee, Han Chan
    • Journal of Bio-Environment Control
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    • v.24 no.3
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    • pp.264-270
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    • 2015
  • Tropical night phenomenon has been increasing due to global warming recently, it is expected that fruit quality of apples will decrease due to elevated night temperature condition. In the present study, fruit quality at maturity, periodic anthocyanin biosynthetic gene expression and sugar contents in leaves and fruit flesh were investigated to establish the physiological responses of 'Fuji' apples under high night temperature. The night temperature were treated with such as ambient (control), ambient $-4^{\circ}C$, and ambient $+4^{\circ}C$. After the treatment, high night temperature didn't affect fruit diameter, weight, and soluble sugar contents. Coloration of ambient $+4^{\circ}C$ was poor than that of control, however there was no significant difference between these genes expression of control and that of ambient $+4^{\circ}C$ treatment in the late coloration season. Increase of sorbitol and glucose contents at ambient $+4^{\circ}C$ in leaves were smaller than those at control, and then sorbitol and sucrose contents in fruit flesh at ambient $+4^{\circ}C$ were smaller than those at control. The cross section of leaves showed that there were no differences with the structure of parenchyma and epidermis tissues between the treatments, but starch granules in the palisade parenchyma cells decreased in high night temperature treatments. Consequently, high night temperature didn't affect the fruit quality, but changed sugar contents in leaves and fruit flesh, and suppressed coloration regardless of anthocyanin biosynthetic gene expression.

Attachment of Silver Nanoparticles to the Wool Fiber Using Glycidyltrimethylammonium Chloride(GTAC) (Glycidyltrimethylammonium Chloride(GTAC)를 이용한 양모 섬유 표면의 Silver Nanoparticle 부착)

  • Lee, Seungyoung;Sul, In Hwan;Lee, Jaewoong
    • Textile Coloration and Finishing
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    • v.28 no.2
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    • pp.70-76
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    • 2016
  • Silver nanoparticles(AgNPs) were attached to wool fibers using glycidyltrimethylammonium chloride(GTAC), which is a type of quaternary ammonium salt. GTAC, which contains an epoxy functional group that, under high temperatures, generates a ring-opening reaction with wool fibers, which contain the amine group. Then, the AgNPs are attached to the surface of the GTAC-treated wool fibers by treatment with a silver colloidal solution. The process involves the following procedures: (1) The wool fibers are immersed in the GTAC solution, followed by pre-drying at $80^{\circ}C$ and curing at $180^{\circ}C$ to induce an alteration in the chemical structure; and (2) The wool fibers treated with GTAC are immersed in the silver colloid at $40^{\circ}C$ for 120 min to chemically induce a strong attachment of the AgNPs to the wool fibers. Scanning electron microscopy was used to analyze the influence of the concentrations of GTAC and the silver colloid, as well as the influence of the applied temperature of the silver colloid on the wool fibers, and the influence of the morphological changes in the wool fiber surfaces. As a result, the enhanced concentrations of GTAC and the silver colloid together with an elevated applied temperature of silver colloid have a tendency to increase in Ag atomic%.

Preparation of Zinc Oxide by Hydrothermal Precipitation Method and their Photocatalytic Characterization (수열합성법에 의한 산화아연의 제조와 광분해 특성)

  • Jeong, Sang-Gu;Na, Seok-Eun;Kim, Si-Young;Ju, Chang-Sik
    • Korean Chemical Engineering Research
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    • v.50 no.5
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    • pp.808-814
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    • 2012
  • Photocatalytic zinc oxide powders were prepared from precursor zinc acetate and ammonia solution at elevated temperature, $80^{\circ}C$, by hydrothermal precipitation method. The effect of operating parameters, pH of ammonia solution and concentration of zinc acetate solution, on the characteristics of zinc oxide powders were experimentally examined. Zinc oxide powders prepared at the conditions of pH 11, zinc acetate concentration of 1.0 M, precipitation temperature of $80^{\circ}C$, showed smallest average particle diameter of $3{\mu}m$. SEM and XRD analysis confirmed that prepared zinc oxide has hexagonal rods structure, and Anatase type crystallinity. In addition, DRS and PL analysis showed that the zinc oxide has activity at the range of 200~400 nm of UV light. And the zinc oxide decomposed 57% of a food-color stamp Brilliant blue FCF for 3 hours under the UV radiation.

Biocontrol Potential of a Lytic Bacteriophage PE204 against Bacterial Wilt of Tomato

  • Bae, Ju Young;Wu, Jing;Lee, Hyoung Ju;Jo, Eun Jeong;Murugaiyan, Senthilkumar;Chung, Eunsook;Lee, Seon-Woo
    • Journal of Microbiology and Biotechnology
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    • v.22 no.12
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    • pp.1613-1620
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    • 2012
  • Bacterial wilt caused by Ralstonia solanacearum is a devastating disease of many economically important crops. Since there is no promising control strategy for bacterial wilt, phage therapy could be adopted using virulent phages. We used phage PE204 as a model lytic bacteriophage to investigate its biocontrol potential for bacterial wilt on tomato plants. The phage PE204 has a short-tailed icosahedral structure and double-stranded DNA genome similar to that of the members of Podoviridae. PE204 is stable under a wide range of temperature and pH, and is also stable in the presence of the surfactant Silwet L-77. An artificial soil microcosm (ASM) to study phage stability in soil was adopted to investigate phage viability under a controlled system. Whereas phage showed less stability under elevated temperature in the ASM, the presence of host bacteria helped to maintain a stable phage population. Simultaneous treatment of phage PE204 at $10^8$ PFU/ml with R. solanacearum on tomato rhizosphere completely inhibited bacterial wilt occurrence, and amendment of Silwet L-77 at 0.1% to the phage suspension did not impair the disease control activity of PE204. The biocontrol activities of phage PE204 application onto tomato rhizosphere before or after R. solanacearum inoculation were also investigated. Whereas pretreatment with the phage was not effective in the control of bacterial wilt, post-treatment of PE204 delayed bacterial wilt development. Our results suggested that appropriate application of lytic phages to the plant root system with a surfactant such as Silwet L-77 could be used to control the bacterial wilt of crops.

The Study on Location and Adsorbate Interaction for Vanadium Species in $VO^{2+}-SAPO-5$ by Electron Spin Resonance and Electron Spin Echo Modulation Spectroscopies

  • Back Gern-Ho;Park Sung-Gun;Lee Chul-Wee
    • Journal of the Korean Magnetic Resonance Society
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    • v.9 no.2
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    • pp.138-154
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    • 2005
  • Vanadium-incorporated aluminophosphate molecular sieve $VO^{2+}-SAPO-5$ was studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies to determine the vanadium structure and interaction with various adsorbate molecules. It was found that the main species at low concentration of vanadium is a monomeric vanadium units in square pyramidal or distorted octahedral coordination, both in oxidation state (IV) for the calcined hydrated material and in oxidation state (V) for the calcined material. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. It is suggested as a $VO(H_2O)_3^{2+}$ complex coordinated to two framework oxygen bonded aluminum. When calcined, hydrated $VO^{2+}-}SAPO-5$ is dehydrated at elevated temperature, a species loses its water ligands and transforms to $VO^{2+}$ ions coordinated to two framework oxygens (species B). Species B reduces its intensity, significantly after treatment with $O_2\;at\;600^{\circ}C$ for 5 h, thus suggesting oxidation of $V^{4+}\;to\;V^{5+}$. When dehydrated $VO^{2+}-SAPO-5$ contacts with $D_2O$ at room temperature, the EPR signal of species A is observed. Thus species assumed as a $VO^{2+}(O_f)_2(D_2O)_3$, by considering two framework oxygens. Adsorption of deuterated ethanol, propanol on dehydrated $VO^{2+}_{-}SAPO-5$ result in another new vanadium species E and F, respectively, which are identified as a $VO^{2+}-(CH_3CH_2OD)_3,\;VO^{2+}-(CH_3CH_2CH_2OD)_2$ complex. When deuterated benzene is adsorbed on dehydrated $VO^{2+}-SAPO-5$, another new vanadium species G, identified as a $VO^{2+}-(C_6D_6)$ is observed. Possible coordination geometries of these various complexes are discussed.

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Fabrication of Ni-Cr-Al Metal Foam-Supported Catalysts for the Steam Methane Reforming (SMR), and its Mechanical Stability and Hydrogen Yield Efficiency (수증기 메탄 개질 반응을 이용한 수소 생산용 Ni-Cr-Al 다공체 지지 촉매의 제조, 기계적 안정성 및 수소 환원 효율)

  • Kim, Kyu-Sik;Kang, Tae-Hoon;Kong, Man Sik;Park, Man-Ho;Yun, Jung-Yeul;Ahn, Ji Hye;Lee, Kee-Ahn
    • Journal of Powder Materials
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    • v.28 no.3
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    • pp.201-207
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    • 2021
  • Ni-Cr-Al metal-foam-supported catalysts for steam methane reforming (SMR) are manufactured by applying a catalytic Ni/Al2O3 sol-gel coating to powder alloyed metallic foam. The structure, microstructure, mechanical stability, and hydrogen yield efficiency of the obtained catalysts are evaluated. The structural and microstructural characteristics show that the catalyst is well coated on the open-pore Ni-Cr-Al foam without cracks or spallation. The measured compressive yield strengths are 2-3 MPa at room temperature and 1.5-2.2 MPa at 750℃ regardless of sample size. The specimens exhibit a weight loss of up to 9-10% at elevated temperature owing to the spallation of the Ni/Al2O3 catalyst. However, the metal-foam-supported catalyst appears to have higher mechanical stability than ceramic pellet catalysts. In SMR simulations tests, a methane conversion ratio of up to 96% is obtained with a high hydrogen yield efficiency of 82%.

Evaluation of Soil Drying Techniques (토양건조방법들에 대한 평가)

  • Lim, Sookil H.
    • Korean Journal of Soil Science and Fertilizer
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    • v.16 no.2
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    • pp.168-178
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    • 1983
  • Influence of several dehydration treatments on original structure and water behavior in the process of drying were investigated employing three hawaiian volcanic ash soils and four synthetic minerals. These three soils were developed under different rainfall condition and contained three different amount of amorphous materials in them. Measurement of water losses by oven drying at $105^{\circ}C$, $P_2O_5$ drying, freeze drying, and critical point drying revealed that more water losses were noted by oven drying than by three other drying techniques and the differences of water losses between oven and $P_2O_5$-drying were closely related to amoun: of amorphous materials in them, showing the order of Kaiwiki > Hilo > Kawaihae. This indicates that dehydration of amorphous materials by elevated temperature ($105^{\circ}C$) excluded water beyond that in the adsorbed (hygroscopic) state. The effect of dehydration treatments on initial structure was visualized by scanning electron microscopy. The micrographs showed that oven-and $P_2O_5$-dried samples formed into large mass of sub-angular blocky, dense, and closed crumbs, while the freeze dried and critical point dried samples resulted in less shrinkage, and small, fluffy and open spongy structure. However, critical point drying technique produced bulkier, softer, and greater open structure samples than even freeze drying. Additional Index Words: original structure, synthetic minerals, critical point drying, $P_2O_5$ drying. 1. This is a part of author's Ph.D. dissertation submitted to the University of Hawaii, Honolulu, Hawaii 96822 in 1979. 2. Professor of Agricultural Chemistry, Korea University.

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VISUALIZATION AND MEASUREMENT OF A NARROW-CONE DI GASOLINE SPRAY FOR THE IMPINGEMENT ANALYSIS

  • Park, J.S.;Im, K.S.;Kim, H.S.;Lai, M.C.
    • International Journal of Automotive Technology
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    • v.5 no.4
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    • pp.221-238
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    • 2004
  • Wall interactions of direct injection spray were investigated using laser-sheet imaging, shadowgraphy, wetted footprint and phase Doppler interferometry techniques. A narrow-cone high-pressure swirl injector is used to inject iso-octane fuel onto a plate, which has three different impact angles inside a pressurized chamber. Heated air and plate conditions were compared with unheated cases. Injection interval was also varied in the heated case to compare dry- and wet- wall impingement behaviors. High-speed macroscopic Mie-scattering images showed that presence of wall and air temperature has only minor effect on the bulk spray structure and penetration speed for the narrow-cone injector tested. The overall bulk motions of the spray plume and its spatial position at a given time are basically unaffected until a few millimeters before impacting the wall. The surface properties of the impact surface, such as the temperature, the presence of a preexisting liquid film also have a small effect on the amount of wetting or the wetted footprint; however, they have strong influence on what occurs just after impact or after a film is formed. The shadowgraph in particular shows that the plate temperature has a significant effect on vapor phase propagation. Generally, 10-20% faster horizontal vapor phase propagation is observed along the wall at elevated temperature condition. For impingement onto a preexisting film, more splash and evaporation were also observed. Contrary to some preconceptions, there is no significant splashing and droplet rebounding from surfaces that are interposed in the path of the DI gasoline spray, especially for the oblique impact angle cases. There also appears to be a dense spray front consists of large sac spray droplets in the oblique impact angle cases. The bulk of the spray is not impacted on the surface, but rather is deflected by it The microscopic details as depicted by phase Doppler measurements show that the outcome of the droplet impaction events can be significantly influenced. Only droplets at the spray front have high enough Weber numbers for wall impact to wet, splash or rebound. Using the sign of vertical velocity, the time-resolved downward droplets and upward droplets are compared. The Weber number of upward moving droplets, which seldom exceeds unity, also decreases as the impact angle decreases, as the droplets tend to impact less and move along the wall in the deflected spray plume.

Study on Temperature Dependence of Molecular Structure in Stearic Acid LB Films Using FTIR-RAS (FTIR-RA 분광법을 이용한 스테아르산 단분자막에서 분자구조의 온도의존성 고찰)

  • Kim, Dong Won;Park, Sang Rae;Umemura Junjo;Takeda Satoshi;Hasegawa Takeshi;Takenaka Tohru;Lee Hai Won
    • Journal of the Korean Chemical Society
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    • v.37 no.6
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    • pp.570-576
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    • 1993
  • 1-, 3-, 9-, and 21-Monolayer Langmuir-Blodgett(LB) films of stearic acid were deposited on silver-coated glass slides at the surface pressure of 30 mN/m. Fourier transform infrared(FTIR) reflection-absorption spectra (RAS) of these LB films were recorded at various temperatures from 31 to $72^{\circ}C.$ The spectra at $31^{\circ}C$ exhibited characteristic features of highly perpendicular orientation of the hydrocarbon chain. In the 1-monolayer LB film, the C=O stretching band was not observed, presumably due to the image dipole effect on the silver surface. In the 1-and 3-monolayer LB films, the trans isomer of stearic acid was prominent, but the cis isomer was dominant in the 21-monolayer LB film. FTIR-RAS measurements at an elevated temperature indicated that the chain melting temperature increases and approached to the bulk melting point with increasing the number of monolayer, except for the 1-monolayer LB film which has a higher melting temperature than the 3-monolayer film due to the strong interaction with the silver substrate.

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