• Title/Summary/Keyword: Heterogeneous Medium

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Activation of Macrophages by Exopolysaccharide Produced by MK1 Bacterial Strain Isolated from Neungee Mushroom, Sarcodon aspratus

  • Im, Sun-A;Wang, Wenxia;Lee, Chong-Kil;Lee, Young-Nam
    • IMMUNE NETWORK
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    • v.10 no.6
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    • pp.230-238
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    • 2010
  • Background: The MK1 strain, a novel bacterial isolate from soft-rotten tissue of the Neungee mushroom, produces copious amounts of exopolysaccharide (EPS) in a dextrose minimal medium. This study examined the molecular characteristics and immunomodulatory activity of MK1 EPS. Methods: The EPS in the culture supernatant was purified by cold ethanol precipitation, and characterized by SDS- PAGE/silver staining and Bio-HPLC. The immunomodulatory activities of the EPS were examined using the mouse monocytic cell line, RAW 264.7 cells. Results: The molecular weights of the purified EPS were rather heterogeneous, ranging from 10.6 to 55 kDa. The EPS was composed of glucose, rhamnose, mannose, galactose, and glucosamine at an approximate molar ratio of 1.00 : 0.8 : 0.71 : 0.29 : 0.21. EPS activated the RAW cells to produce cytokines, such as TNF-${\alpha}$ and IL-$1{\beta}$, and nitric oxide (NO). EPS also induced the expression of co-stimulatory molecules, such as B7-1, B7-2 and ICAM-1, and increased the phagocytic activity. The macrophage-activating activity of EPS was not due to endotoxin contamination because the treatment of EPS with polymyin B did not reduce the macrophage-activating activity. Conclusion: The EPS produced from the MK1 strain exerts macrophage-activating activity.

Performance Evaluation of Various Bus Clamped Space Vector Pulse Width Modulation Techniques

  • Nair, Meenu D.;Biswas, Jayanta;Vivek, G.;Barai, Mukti
    • Journal of Power Electronics
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    • v.17 no.5
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    • pp.1244-1255
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    • 2017
  • The space vector pulse width modulation (SVPWM) technique is a popular PWM method for medium voltage drive applications. Conventional SVPWM (CSVPWM) and bus clamped SVPWM (BCSVPWM) are the most common SVPWM techniques. This paper evaluates the performance of various advanced BCSVPWM strategies in terms of their harmonic distortion and switching loss based on a uniform frame work. A uniform frame work, pulse number captures the performance parameter variations of different SVPWM strategies for various number of samples with heterogeneous pulse numbers. This work compares different advanced BCSVPWM techniques based on the modulation index and location of the clamping position (zero vector changing angle ) of a phase in a line cycle. The frame work provides a fixed fundamental frequency of 50Hz. The different BCSVPWM switching strategies are implemented and compared experimentally on a 415V, 2.2kW, 50Hz, 3-phase induction motor drive which is fed from an IGBT based 2 KVA voltage source inverter (VSI) with a DC bus voltage of 400 V. A low cost PIC microcontroller (PIC18F452) is used as the controller platform.

Comparative study of torsional wave profiles through stratified media with fluted boundaries

  • Maity, Manisha;Kundu, Santimoy;Kumari, Alka;Gupta, Shishir
    • Structural Engineering and Mechanics
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    • v.74 no.1
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    • pp.91-104
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    • 2020
  • A mathematical analysis has been carried out for understanding the traversal attributes of torsional waves in a Voigt-type viscoelastic porous layer bounded with corrugated surfaces resting over a heterogeneous transversely isotropic gravitating semi-infinite medium. Both the media are assumed to be under the effect of initial stresses acting along horizontal directions. In the presumed geometry, continuous and periodic type of corrugation has been considered. The condensed form of dispersion relation has been obtained analytically with the aid of the Whittaker's function and suitable boundary conditions. The influence of viscoelasticity, porosity, initial stresses, heterogeneity, gravity, undulation and position parameters on the phase and damped velocities has been illustrated graphically. In addition, relative examination investigating the impact of corrugated and planar bounded surfaces on the dispersion and damping characteristics is one of the important highlights of this study.

Effect of oxygen distribution for hot spot and carbon deposition minimization in a methane autothermal reforming reactor

  • Lee, Shin-Ku;Bae, Joong-Myeon;Kim, Yong-Min;Park, Joong-Uen;Lim, Sung-Kwang
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.1996-2000
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    • 2008
  • In autothermal reforming reaction, oxygen to carbon ratio (OCR) and steam to carbon ratio (SCR) are significant factors, which control temperature and carbon deposition into the reactor. The OCR is more sensitive than the SCR to affect the temperature distribution and reforming efficiency. In conventional operation, hydrocarbon fuel, steam, and oxygen was homogeneously mixed and injected into the reactor in order to get hydrogen-rich gas. The temperature was abruptly raised due to fast oxidation reaction in the former part of the reactor. Deactivation of packed catalysts can be accelerated there. In the present study, therefore, the effect of the oxygen distribution is introduced and investigated to suppress the carbon deposition and to maintain the reactor in the mild operating temperature (e.g., $700{\sim}800^{\circ}C$). In order to investigate the effect numerically, the following models are adopted; heterogeneous reaction model and two-medium model for heat balance.

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The effect of high concentration of glucose on the production of proinflammatory cytokines and nitric oxide induced by lipopolysaccharides from periodontopathic bacteria (고농도의 글루코스가 치주질환 병인균주의 세균내독소에 의한 염증성 cytokine 및 nitric oxide의 생성에 미치는 영향)

  • Kim, Sung-Jo
    • Journal of Periodontal and Implant Science
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    • v.38 no.3
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    • pp.511-520
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    • 2008
  • Purpose: Diabetes mellitus is a clinically and genetically heterogeneous group of metabolic disorders manifested by abnormally high levels of glucose in the blood. Mounting evidence demonstrates that diabetes is a risk factor for gingivitis and periodontitis. The circulating mononuclear phagocytes in diabetic patients with hyperglycemia are chronically exposed to high level of serum glucose. Thus, this study attempted to determine the effect of pre-exposure of monocytes and macrophages to high concentration of glucose on lipopolysaccharide (LPS)-induced production of pro-inflammatory mediators. Material and Methods: For this purpose, cells were cultured in medium containing normal (5 mM) or high glucose (25 mM) for 4-5 weeks before treatment for 24 h with LPS. LPS was highly purified from Porphyromonas gingivalis or Prevotella intermedia by phenol extraction. Result: Results showed that prolonged pre-exposure of cells to high glucose markedly increased LPS-stimulated NO secretion when compared to normal glucose. In addition to NO, high glucose also augmented LPS-stimulated IL-6, IL-8, and TNF-$\alpha$ secretion after cells were exposed to high glucose for 4 weeks. Conclusion: The present study demonstrates that pre-exposure of mononuclear phagocytes with high glucose augments LPS-stimulated production of pro-inflammatory mediators. These findings may explain why periodontal tissue destruction in diabetic patients is more severe than that in non-diabetic individuals.

A Study on Design Characteristics of Artistic Space effected by Light in 'Light and Space Art' (빛과 공간예술에서 빛에 의한 공간의 표현특성에 관한 연구)

  • Suh Jeong-Yeon
    • Korean Institute of Interior Design Journal
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    • v.14 no.4 s.51
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    • pp.35-44
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    • 2005
  • Light is the essential and symbolical entity In architecture. But the meaning of light has been changed as time has passed, and today it has plural meaning and more sophisticated role. Since 1960's 'Light and Space Art' has accomplished many successful experiments through light and space as artistic media, and they have changed the understanding of light from the electrical source to the phenomenological energy and sensual medium. And also the role of space in their works takes the more human-oriented field constituted from the coherent relationship of internal parts including human being. Light could be 'an object' and 'material' under 'Light and Space Art' artists' persistent efforts. They revealed another realm of spatial experiences such as extension-the metaphysical space, heterogeneous relationship-the complex space, and dematerialization-the illusionary space. The secondary and inclusive effects by 'Light and Space Art' can be found In the phenomenological architecture, the post-modern architecture, and the immaterial tendency of contemporary architecture. However, the more close connections between 'Light and Space Art' and the specific architectures are still left as a portion aside for the further research.

Replacing C3S cement with PP fibre and nanobiosilica in stabilisation of organic clays

  • Soheil Ghadr;Arya Assadi-Langroudi;Hadi Bahadori
    • Geomechanics and Engineering
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    • v.33 no.4
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    • pp.401-414
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    • 2023
  • Organic clays are ideal habitat for flora and fauna. From a geotechnical perspective, organic clays are soft, weak, variable, heterogeneous and flocculated. Portland cement is a universally common stabiliser. However, some organic acids in soil inhibit full hydration and expose cementation products to rapid dissolution. This paper investigates scopes for use of C3S cement to enable durable cementation. Prospects of using PP fibre alongside with C3S cement, scopes for partial replacement of C3S cement with a plant-based nanosilica and evolution of binders are then investigated. Binding mixtures here mimic the natural functions of rhizoliths, amorphous phases, and calcites. Testing sample population include natural and fibre-reinforced clays, compact mixes of clay - C3S cement, clay - nanobiosilica, and clay, C3S cement and nanobiosilica. Benefits and constraints of C3S cement and fibres for retaining the naturally flocculated structure of organic clays are discussed. Nanobiosilica provides an opportunity to cut the C3S content, and to transition of highly compressive organic clays into an engineered, open-structured medium with >0.5 MPa compressive strength across the strains spanning from peak to 1.5-times peak.

Development of Cryopreservation Protocols through Droplet-vitrification and its Application to Vegetatively Propagated Crop Germplasm (영양체 유전자원의 작은방울-유리화법에 의한 초저온동결보존 실용화기술개발)

  • Kim, Haeng-Hoon;Yi, Jung-Yoon;No, Na-Young;Cho, Gyu-Taek;Yoon, Mun-Sup;Baek, Hyung-Jin;Kim, Chung-Kon
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2010.05a
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    • pp.12-12
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    • 2010
  • We developed droplet-vitrification protocol, a combination of droplet-freezing and solution-based vitrification, and applied to germplasm collections of garlic, potato, lily as well as cell lines, including hairy roots, somatic embryos. To establish a garlic cryobank, four Korean garlic field collections at Danyang, Suwon, Mokpo and Namhae were cryopreserved last five years. The protocol applied consisted of preculture for 3-4 days at $10^{\circ}C$ on solid MS medium with 0.3M sucrose, loading for 40 min in liquid medium with 35% PVS3, dehydration with PVS3 for 150 min, cooling in $5{\mu}l$ droplets of PVS3 placed on aluminum foil strips by dipping these strips in liquid nitrogen, warming them by plunging the foil strips into pre-heated($40^{\circ}C$) 0.8M sucrose solution for 30s. A total of over 900 accessions of garlic were stored in liquid nitrogen for long-term conservation using unripe inflorescences, cloves or bulbils. Twelve alternative plant vitrification solutions were designed by modifying cryoprotectant concentrations from the original PVS2 and PVS3. The results suggest that PVS2-based vitrification solutions with increased glycerol and sucrose and/or decreased DMSO and EG concentrations can be applied for medium size explants which are tolerant to chemical toxicity and moderately sensitive to osmotic stress. PVS3 and variants can be used widely when samples are heterogeneous, of large size and/or very sensitive to chemical toxicity and tolerant to osmotic stress.

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Isolation and Phylogenetic Characterization of Chitinase Producing Oligotrophic Bacteria (Chitinase생산 저영양세균의 분리 및 계통분류학적 특성)

  • Kim Soo-Jin;Kim Min-Young;Koo Bon-Sung;Yoon San-Hong;Yeo Yun-Soo;Park In-Cheol;Kim Yoon-Ji;Lee Jong-Wha;Whang Kyung-Sook
    • Korean Journal of Microbiology
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    • v.41 no.4
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    • pp.293-299
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    • 2005
  • Many isolates from soil of Korean ginseng rhizosphere did not show remarkable growth on full strength of the conventional nutrient broth (NB medium) but grew on its 100-fold dilution (DNB medium). Six hundred-forty strains were isolated as oligotrophic bacteria. In the course of screening for new bioactive compounds from oligotrophic bacteria from soil, 8 strains which had appeared to form of clear zone on a medium containing colloidal chitin as a sole carbon source were selected for further studies. Strain CR42 hydrolyzed a fluorogenic analogue of chitin, 4-methylumbelliferyl-D-glucosaminide (MUF-NAG) . Mo st of the culture supernatant of these isolates hydrolyzed 4-methylumbelliferyl-D-N,N'-diacetylchitobioside (MUF-diNAG). The isolates were heterogeneous and categorized to gamma- and beta-proteobacteria, Bacillaceae, Actinobactepia, and Bacteroides by 16S rRNA analysis. Two strains, WR164 and CR18, had a 16S rRNA sequence of $95-96\%$ identical to uncultured bacteria. It was observed that CR2 and CR75 could inhibit the growth of Colletotrichum gloeosporioides with hyphal extention-inhibition assay on PDA plate supplemented with $1\%$ colloidal chitin.

A Nuclide Transport Model in the Fractured Rock Medium Using a Continuous Time Markov Process (연속시간 마코프 프로세스를 이용한 균열암반매질에서의 핵종이동 모델)

  • Lee, Y.M.;Kang, C.H.;Hahn, P.S.;Park, H.H.;Lee, K.J.
    • Nuclear Engineering and Technology
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    • v.25 no.4
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    • pp.529-538
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    • 1993
  • A stochastic way using continuous time Markov process is presented to model the one-dimensional nuclide transport in fractured rock matrix as an extended study for previous work [1]. A nuclide migration model by the continuous time Markov process for single planar fractured rock matrix, which is considered as a transient system where a process by which the nuclide is diffused into the rock matrix from the fracture may be no more time homogeneous, is compared with a conventional deterministic analytical solution. The primary desired quantities from a stochastic model are the expected values and variance of the state variables as a function of time. The time-dependent probability distributions of nuclides are presented for each discretized compartment of the medium given intensities of transition. Since this model is discrete in medium space, parameters which affect nuclide transport could be easily incorporated for such heterogeneous media as the fractured rock matrix and the layered porous media. Even though the model developed in this study was shown to be sensitive to the number of discretized compartment showing numerical dispersion as the number of compartments are decreased, with small compensating of dispersion coefficient, the model agrees well to analytical solution.

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