• Title/Summary/Keyword: Free Water

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Surveillance of Acanthamoeba spp. and Naegleria fowleri in environmental water by using the duplex real-time PCR (Duplex real-time PCR을 이용한 수계 중 가시아메바와 파울러자유아메바 조사)

  • Kim, Min-jeong;Lee, Gyu-Cheol;Kim, Kunwoo;Lee, Hyunji;Kim, Min Young;Seo, Dae Keun;Lee, Jeong Yeob;Cho, Young-Cheol
    • Korean Journal of Microbiology
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    • v.54 no.2
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    • pp.98-104
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    • 2018
  • Naegleria fowleri and Acanthamoeba spp. are free-living amoebas that are widely distributed in natural environments. Although uncommon, infection with these protozoans can cause fatal disease in humans and animals. In this study, in order to select the appropriate method to survey Naegleria fowleri and Acanthamoeba spp. in water samples, four molecular biology techniques and one commercially available kit for real-time PCR were compared. The results indicated that the duplex real-time PCR was the most sensitive, and could be used to simultaneously detect two different free-living amoebas. Using the duplex real-time PCR approach, the two free-living amoebas were surveyed in three local streams in Daejeon, Republic of Korea. The concentrated free-living amoebas were inoculated onto non-nutrient agar plates which had been spread with heat-inactivated Escherichia coli and incubated for 5~7 days. After incubation, gDNA was extracted and used as the template for amplification by duplex real-time PCR. Acanthamoeba spp. and N. fowleri was detected from ten (83.3%) and two (16.6%) of the twelve samples, respectively. As these two free-living amoebas can be fatal, continuous surveillance is needed to track their distribution in the aquatic environment for the drinking water safety.

PIV Analysis of Free Surface Effects on Flow Around a Rotating Propeller with Varying Water Depth (자유표면과 수심깊이가 회전하는 프로펠러 주위 유동에 미치는 영향에 대한 PIV 해석)

  • Paik, Bu-Geun;Lee, Jung-Yeop;Lee, Sang-Joon
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.5 s.143
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    • pp.427-434
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    • 2005
  • The free surface influenced the wake behind a rotating propeller and its effects were investigated experimentally in a circulating water channel with the variation of water depth. Instantaneous velocity fields were measured using two-frame PIV technique and ensemble-averaged to study the phase-averaged flow structure in the wake region. For an isolated propeller, the flow behind the propeller is affected only by the propeller rotation speed, the leading on the blades and the proximity of the propeller to the free surface. The phase-averaged mean velocity fields show that the potential wake and the viscous wake developed on the blade surfaces. The interaction between the tip vortices and the slipstream causes the oscillating trajectory of tip vortices. The presence of the free surface greatly affected the wake structure, especially for propeller immersion depth of 0.6D. At small immersion depths, the free surface modified the tip and trailing vortices and the slipstream flow structure downstream of X/D = 0.3 in the propeller wake.

A three-dimensional numerical model for shallow water flows using a free surface correction method (자유수면 보정기법을 이용한 3차원 천수유동 수치모형)

  • Jang, Won-Jae;Lee, Seung-Oh;Cho, Yong-Sik
    • 한국방재학회:학술대회논문집
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    • 2007.02a
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    • pp.181-185
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    • 2007
  • A free-surface correction(FSC) method is presented to solve the 3-D shallow water equations. Using the mode splitting process, FSC method can simulate shallow water flows under the hydrostatic assumption. For the hydrostatic pressure calculation, the momentum equations are firstly discretized using a semi-implicit scheme over the vertical direction leading to the tri-diagonal matrix systems. A semi-implicit scheme has been adopted to reduce the numerical instability caused by relatively small vertical length scale compare to horizontal one. and, as the free surface correction step the final horizontal velocity fields are corrected after the final surface elevations are obtained. Finally, the vertical final velocity fields can be calculated from the continuity equation. The numerical model is applied to the calculation of the simulation of flow fields in a rectangular open channel with the tidal influence. The comparisons with the analytical solutions show overall good agreements between the numerical results and analytical solutions.

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Simulation of free falling rigid body into water by a stabilized incompressible SPH method

  • Aly, Abdelraheem M.;Asai, Mitsuteru;Sonoda, Yoshimi
    • Ocean Systems Engineering
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    • v.1 no.3
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    • pp.207-222
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    • 2011
  • A stabilized incompressible smoothed particles hydrodynamics (ISPH) method is utilized to simulate free falling rigid body into water domain. Both of rigid body and fluid domain are modeled by SPH formulation. The proposed source term in the pressure Poisson equation contains two terms; divergence of velocity and density invariance. The density invariance term is multiplied by a relaxed parameter for stabilization. In addition, large eddy simulation with Smagorinsky model has been introduced to include the eddy viscosity effect. The improved method is applied to simulate both of free falling vessels with different materials and water entry-exit of horizontal circular cylinder. The applicability and efficiency of improved method is tested by the comparisons with reference experimental results.

Textural Properties of Gluten-free Rice Pasta Prepared Employing Various Starches (전분을 첨가한 글루텐 프리 쌀 파스타의 텍스처 특성)

  • Jung, Jin Hyuck;Yoon, Hye Hyun
    • Korean journal of food and cookery science
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    • v.33 no.1
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    • pp.28-36
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    • 2017
  • Purpose: This study was conducted to understand the factors that affect the texture of gluten-free rice pasta prepared buckwheat, mung bean, and acorn starches and to compare textural properties of samples 100% semolina. Methods: The moisture content, weight and water absorption test investigated and texture profile analysis measured by texture analyzer. Results: 100% semolina sample's value was lower than gluten-free rice pasta moisture content, weight and water absorption test. moisture content weight was in pasta with mung bean starchin pasta with buckwheat starch. Texture profile analysis showed that increasing amount of buckwheat, mung bean, and acorn starches increased hardness, chewiness, cohesiveness and springiness, and decreased adhesiveness of gluten free rice pasta. Conclusion: This study suggested that adding buckwheat, mungbean and acorn starches could improve texture properties of gluten-free rice pasta.

Changes in bound water and microstructure during consolidation creep of Guilin red clay

  • Zhang, Dajin;Xiao, Guiyuan;Yin, Le;Xu, Guangli;Wang, Jian
    • Geomechanics and Engineering
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    • v.30 no.5
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    • pp.471-478
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    • 2022
  • Creep of soils has a significant impact on mechanical properties. The one-dimensional consolidation creep test, thermal analysis test, scanning electron microscope (SEM) test, and mercury compression test were performed on Guilin red clay to study the changes in bound water and microstructure during the creep process of Guilin red clay. According to the results of the tests, only free and weakly bound water is discharged during the creep of Guilin red clay. When the consolidation pressure p is in the 12.5-400.0 kPa range, it is primarily the discharge of free water; when the consolidation pressure p is in the 800.0-1600.0 kPa range, the weakly bound water is converted to free water and discharged. After consolidation creep, the microstructure of soil changes from granular overhead contact structure to flat sheet-like stacking structure, with a decrease in the number of large and medium pores, an increase in the number of small and micro pores, and a decrease in the fractal dimension of pores. The creep process of red clay is the discharge of weakly bound water as well as the compression of large pores into small pores and the transition of soil particles from loose to dense.

Distribution of Acanthamoeba spp. in Raw Water and Water Treatment Process (상수원수 및 정수처리공정별 가시아메바 분포특성에 관한 연구)

  • Jung, Eun-Young;Jung, Mi-Eun;Park, Hong-Gi;Jung, Jong-Moon;Rho, Jae-Sun;Ryu, Pyung-Jong
    • Journal of Environmental Science International
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    • v.17 no.10
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    • pp.1121-1127
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    • 2008
  • The free-living amoeba and Acanthamoeba sp. are widely distributed in fresh water, soil, air and dust in the world. We studied distribution of amoeba from low Nakdong River(Mulgum and Maeri) and removal efficiency in water treatment process of Busan metropolitan city. During this investigation, water quality showed pH $7.4{\sim}9.6({\pm}1.1)$, water temperature $2.0{\sim}29.0({\pm}17)^{\circ}C$, turbidity $4.8{\sim}27.4({\pm}11.0)$ NTU, chlorophyll-a $10.3{\sim}109.0({\pm}44.3)\;mg/m^{3}$, BOD $1.7\sim4.9({\pm}2.6)$ mg/L, COD $3.1\sim-6.9({\pm}5.0)$ mg/L and total coliform $17\sim920({\pm}200.5)$ MPN/100 mL. The free-living amoeba were detected highly than Acanthamoeba sp., 11 out of 22 in raw water samples were positive (50%) for Acanthamoeba sp. from February 2005 to December 2005. The seasonal characteristics of tree-living amoeba and Acanthamoeba sp. in raw water were mainly distributed through the spring to the early fall. When tree-living amoeba and Acanthamoeba sp. were passed through the water treatment of pilot-plant, approximately 80% was sure to be removed through pre-ozonation, sedimentation, send filtration. 100% was removed after post-ozonation process. All of the isolated amoebas from Nakdong River were Acanthamoeba sp. AC311 18S ribosomal RNA gene with 98% nucleotide sequence homology.

Effect of high free ammonia concentration on microalgal growth and substrate uptake (폐수 내 고농도 free ammonia(FA)가 미세조류의 성장 및 기질제거에 미치는 영향 평가)

  • Kim, Eun-Ji;Cho, Jae Hyung;Noh, Kyung Ho;Nam, guisook;Hwang, Sun-Jin
    • Journal of Korean Society of Water and Wastewater
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    • v.30 no.6
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    • pp.715-723
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    • 2016
  • This study investigated the effect of high concentration of free ammonia on microalgal growth and substrate removal by applying real wastewater nitrogen ratio. To test of this, the conditions of free ammonia 1, 3, 6, 9, 12, 15 mg-N/L are compared. After 3 days of incubation, algal growth of Chlorella vulgaris and carbon removal rate are respectively lower in the reactors of FA 12, 15 mg-N/L compared to the others. This indicates that the high concentration of free ammonia, in this case, above 12 mg-N/L, has negative effect on algal growth and metabolic activity. Also, high concentration of free ammonia causes the proton imbalance, ammonium accumulation in algae and has toxicity for these reasons. So, we have to consider free ammonia in applying the microalgae to wastewater treatment system by the way of diluting wastewater or controlling pH and temperature.

Studies on Deer Horn (I) Free Amino acids of Deer Horn Water Extract (녹용에 관한 연구 (제 1 보) 녹용수침액의 유리아미노산에 대하여)

  • 용재익;백남호
    • YAKHAK HOEJI
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    • v.5 no.1
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    • pp.1-2
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    • 1960
  • Six kinds of free amino acids, leucine, methionine, threonine, lysine, histidine and aspartic acid were found by using partition paper chromatography from water extract of deer horn which is widely used as tonic drug. The results shows that deer horn does not contain any specific free amino acid.

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Free Surface Flow in a Trench Channel Using 3-D Finite Volume Method

  • Lee, Kil-Seong;Park, Ki-Doo;Oh, Jin-Ho
    • Journal of Korea Water Resources Association
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    • v.44 no.6
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    • pp.429-438
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    • 2011
  • In order to simulate a free surface flow in a trench channel, a three-dimensional incompressible unsteady Reynolds-averaged Navier-Stokes (RANS) equations are closed with the ${\kappa}-{\epsilon}$ model. The artificial compressibility (AC) method is used. Because the pressure fields can be coupled directly with the velocity fields, the incompressible Navier-Stokes (INS) equations can be solved for the unknown variables such as velocity components and pressure. The governing equations are discretized in a conservation form using a second order accurate finite volume method on non-staggered grids. In order to prevent the oscillatory behavior of computed solutions known as odd-even decoupling, an artificial dissipation using the flux-difference splitting upwind scheme is applied. To enhance the efficiency and robustness of the numerical algorithm, the implicit method of the Beam and Warming method is employed. The treatment of the free surface, so-called interface-tracking method, is proposed using the free surface evolution equation and the kinematic free surface boundary conditions at the free surface instead of the dynamic free surface boundary condition. AC method in this paper can be applied only to the hydrodynamic pressure using the decomposition into hydrostatic pressure and hydrodynamic pressure components. In this study, the boundary-fitted grids are used and advanced each time the free surface moved. The accuracy of our RANS solver is compared with the laboratory experimental and numerical data for a fully turbulent shallow-water trench flow. The algorithm yields practically identical velocity profiles that are in good overall agreement with the laboratory experimental measurement for the turbulent flow.