scholarly journals F123 Layered convection due to thermal plume in linear concentration gradient system

2006 ◽  
Vol 2006 (0) ◽  
pp. 199-200
Author(s):  
Katsuyoshi KAMAKURA ◽  
Hiroyuki HIRANO ◽  
Hiroyuki OZOE
Keyword(s):  
Concentration Gradient ◽  
Gradient System ◽  
Thermal Plume ◽  
Linear Concentration

scholarly journals Quantitative analysis of single bacterial chemotaxis using a linear concentration gradient microchannel

2009 ◽  
Vol 11 (5) ◽  
pp. 1135-1143 ◽  
Author(s):  
Hojeong Jeon ◽  
Yongku Lee ◽  
Songwan Jin ◽  
Sangmo Koo ◽  
Chang-Soo Lee ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Concentration Gradient ◽  
Bacterial Chemotaxis ◽  
Linear Concentration

Electrokinetic Concentration Gradient Generation Using a Converging-Diverging Microchannel

2005 ◽  
Author(s):  
Jacky S. H. Lee ◽  
Yandong Hu ◽  
Dongqing Li
Keyword(s):  
Concentration Gradient ◽  
Electroosmotic Flow ◽  
Channel Length ◽  
Concentration Profiles ◽  
Concentration Gradients ◽  
Simple Method ◽  
Gradient Generator ◽  
Gradient Generation ◽  
Diffusive Mixing ◽  
Linear Concentration

Creation of concentration gradients is important in the study of biological and chemical processes that are sensitive to concentration variations. This paper presents a simple method to generate a linear concentration gradient in electroosmotic flow in microchannels with converging and diverging geometries. The method is based on the enhanced diffusive mixing inside the microchannel. By varying the converging-diverging geometries, the degree of diffusive mixing can be controlled. Different concentration gradients can be obtained by varying the applied potential and the geometry. Concentration profiles with minimal axial variations can be achieved with a deviation of 7% and 3% over a channel length of 3mm and 1mm, respectively, for a 400μm wide microchannel. Although the underlying physics and mechanisms for creating concentration profiles in a converging-diverging microchannel are the same as a T-shaped micromixer, the converging-diverging microchannel can produce desired concentration profiles in a much shorter distance (shorter by a factor of 2∼3.5 compared to a T-shape mixer). A serially connected concentration gradient generator is also realized with the ability to generate two concentration gradient ranges in the same microchannel. Numerical simulations and experiments were carried out to investigate the factors contributed to the generation of the concentration gradients.

scholarly journals A computational study of phase separation in polymer solutions under a concentration gradient

2021 ◽  
Author(s):  
Baitao Jiang
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Spinodal Decomposition ◽  
Concentration Gradient ◽  
Computational Study ◽  
Polymeric Materials ◽  
Polymeric Membranes ◽  
Separation Processes ◽  
Initial Concentration ◽  
Linear Concentration

Anisotropic porous polymeric materials fabricated from the phase separation method via spinodal decomposition are used in various practical engineering applications. Examples include anisotropic porous polymeric membranes for separation processes and holographic polymer dispersed liquid crystal films for electro-optical devices. We have studied numerically the formation of anisotropic porous polymeric materials by imposing an initial linear concentration gradient across a model polymer solution. The mathematical model is composed of the non-linear Cahn-Hilliard theory to describe spinodal decomposition dynamics, the Flory-Huggins theory for polymer solution thermodynamics, and the slow mode theory combined with the Rouse law for polymer diffusion. The computer simulations include uniform (no gradient) and non-uniform (with an initial concentration gradient) cases. For the non-uniform cases, the initial concentration gradient is placed at three different regions of polymer sample for the purpose of comparison. All the simulation results are in good agreement with published experimental observations which are reported from the applications of porous polymeric membranes. The structure development shows that an anisotropic porous morphology forms when an initial linear concentration gradient is applied to the model polymer solution.

scholarly journals A computational study of phase separation in polymer solutions under a concentration gradient

2021 ◽  
Author(s):  
Baitao Jiang
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Spinodal Decomposition ◽  
Concentration Gradient ◽  
Computational Study ◽  
Polymeric Materials ◽  
Polymeric Membranes ◽  
Separation Processes ◽  
Initial Concentration ◽  
Linear Concentration

Anisotropic porous polymeric materials fabricated from the phase separation method via spinodal decomposition are used in various practical engineering applications. Examples include anisotropic porous polymeric membranes for separation processes and holographic polymer dispersed liquid crystal films for electro-optical devices. We have studied numerically the formation of anisotropic porous polymeric materials by imposing an initial linear concentration gradient across a model polymer solution. The mathematical model is composed of the non-linear Cahn-Hilliard theory to describe spinodal decomposition dynamics, the Flory-Huggins theory for polymer solution thermodynamics, and the slow mode theory combined with the Rouse law for polymer diffusion. The computer simulations include uniform (no gradient) and non-uniform (with an initial concentration gradient) cases. For the non-uniform cases, the initial concentration gradient is placed at three different regions of polymer sample for the purpose of comparison. All the simulation results are in good agreement with published experimental observations which are reported from the applications of porous polymeric membranes. The structure development shows that an anisotropic porous morphology forms when an initial linear concentration gradient is applied to the model polymer solution.

scholarly journals Motion of an active particle in a linear concentration gradient

2021 ◽  
Vol 33 (3) ◽  
pp. 032011
Author(s):  
Prathmesh M. Vinze ◽  
Akash Choudhary ◽  
S. Pushpavanam
Keyword(s):  
Concentration Gradient ◽  
Active Particle ◽  
Linear Concentration

Antibiotic susceptibility test under a linear concentration gradient using travelling surface acoustic waves

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Yongtaek Im ◽  
Seunggyu Kim ◽  
Jinsoo Park ◽  
Hyung Jin Sung ◽  
Jessie Sungyun Jeon
Keyword(s):  
Antimicrobial Resistance ◽  
Concentration Gradient ◽  
Acoustic Waves ◽  
Antibiotic Susceptibility ◽  
Pathogenic Bacteria ◽  
Inhibitory Concentration ◽  
Surface Acoustic Waves ◽  
Susceptibility Test ◽  
Antibiotic Susceptibility Test ◽  
Linear Concentration

An efficient and accurate antibiotic susceptibility test (AST) is indispensable for measuring the antimicrobial resistance of pathogenic bacteria. A minimal inhibitory concentration (MIC) can be obtained without performing repeated dilutions...

scholarly journals Continuous measurement of soil CO<sub>2</sub> efflux in a larch forest by automated chamber and concentration gradient techniques

2010 ◽  
Vol 7 (1) ◽  
pp. 1345-1375
Author(s):  
N. Liang ◽  
T. Hirano ◽  
Z.-M. Zheng ◽  
J. Tang ◽  
Y. Fujinuma
Keyword(s):  
Concentration Gradient ◽  
Soil Co2 Efflux ◽  
Larch Forest ◽  
Heterotrophic Respiration ◽  
Large Temperature ◽  
Gradient System ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Gradient Approach ◽  
Chamber Technique

Abstract. Winter measurements of soil CO2 effluxes are few because such measurements are difficult when the ground is snow-covered, limiting the ability of chamber systems to characterize soil CO2 effluxes accurately year-round. In this study, we used two systems for continuous measurements of soil CO2 effluxes in a larch forest in northern Japan: (1) a 16-channel automated soil chamber system with eight chambers for measuring soil CO2 efflux and eight chambers for measuring heterotrophic respiration during snow-free periods, and (2) a soil CO2 concentration gradient system used year-round, including when the ground was snow-covered. During the warm season, the gradient approach yielded systematically higher CO2 effluxes than the automated chamber technique, whereas it yielded lower CO2 effluxes during the cold season. As a result of this bias (p<0.001), the annual soil CO2 efflux estimated by the automated chamber was 959 g C m−2 (of which 57% was contributed by heterotrophic respiration), whereas the efflux estimated by the gradient approach was 1040 g C m−2. Because of the fast-response infrared gas analyzer adopted for the chamber technique, the soil CO2 efflux response to the onset of rain was detected immediately and the efflux returned to pre-rain values several hours after the rain had stopped. Rain events accounted for about 24 g C m−2 (about 2% of the annual soil CO2 efflux). The gradient system successfully measured the soil CO2 effluxes when the ground was snow-covered (9 December to 17 April), when they ranged from 0.40 to 0.70 μmol m−2 s−1. Total CO2 efflux from the snowpack estimated by the gradient technique approached 73 g C m−2, corresponding to about 7% of the annual soil CO2 efflux. The Q10 coefficient of the soil CO2 efflux showed large seasonal variation, mainly because of the large temperature sensitivity of root respiration.

Generation of flow and droplets with ultra-long-range linear concentration gradient

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Bo Dai ◽  
Yan Long ◽  
Jiandong Wu ◽  
Shaoqi Huang ◽  
Yuan Zhao ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Long Range ◽  
Drug Screening ◽  
Concentration Gradient ◽  
Important Approach ◽  
Linear Concentration

In the chemical and biological fields, creation of concentration gradient microenvironment is an important approach for many applications, such as crystal growth and drug screening. Although many concentration gradient generators...

A concentration gradient system

1978 ◽  
Vol 86 (2) ◽  
pp. 432-442 ◽  
Author(s):  
Budin M. Michov
Keyword(s):  
Concentration Gradient ◽  
Gradient System
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