scholarly journals Passive Dielectrophoretic Focusing of Particles and Cells in Ratchet Microchannels

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 451 ◽  
Author(s):  
Song-Yu Lu ◽  
Amirreza Malekanfard ◽  
Shayesteh Beladi-Behbahani ◽  
Wuzhou Zu ◽  
Akshay Kale ◽  
...  
Keyword(s):  
Particle Size ◽  
Yeast Cells ◽  
Movement Direction ◽  
Theoretical Formula ◽  
Scaling Analysis ◽  
Particle Movement ◽  
Fundamental Study ◽  
Minimal Impact ◽  
Stream Width ◽  
Particle Stream

Focusing particles into a tight stream is critical for many microfluidic particle-handling devices such as flow cytometers and particle sorters. This work presents a fundamental study of the passive focusing of polystyrene particles in ratchet microchannels via direct current dielectrophoresis (DC DEP). We demonstrate using both experiments and simulation that particles achieve better focusing in a symmetric ratchet microchannel than in an asymmetric one, regardless of the particle movement direction in the latter. The particle focusing ratio, which is defined as the microchannel width over the particle stream width, is found to increase with an increase in particle size or electric field in the symmetric ratchet microchannel. Moreover, it exhibits an almost linear correlation with the number of ratchets, which can be explained by a theoretical formula that is obtained from a scaling analysis. In addition, we have demonstrated a DC dielectrophoretic focusing of yeast cells in the symmetric ratchet microchannel with minimal impact on the cell viability.

scholarly journals Nanotoxicity of polyelectrolyte-functionalized titania nanoparticles towards microalgae and yeast: role of the particle concentration, size and surface charge

RSC Advances ◽  
2015 ◽  
Vol 5 (46) ◽  
pp. 37044-37059 ◽  
Author(s):  
Mohammed J. Al-Awady ◽  
Gillian M. Greenway ◽  
Vesselin N. Paunov
Keyword(s):  
Particle Size ◽  
Surface Charge ◽  
Particle Concentration ◽  
Yeast Cells ◽  
Titania Nanoparticles ◽  
Green Microalgae

We explore the effects of the particle size and the surface charge of polyelectrolyte-coated titania nanoparticles on their toxicity towards green microalgae and yeast cells in UV/vis light.

scholarly journals Sedimentation of Irregular Shaped Microplastics Under Steady and Dynamic Flow Conditions

2021 ◽  
Author(s):  
Zhen Wang ◽  
Ming Dou ◽  
Pengju Ren ◽  
Bin Sun ◽  
Ruipeng Jia ◽  
...  
Keyword(s):  
Particle Size ◽  
Theoretical Formula ◽  
Water Density ◽  
Force Analysis ◽  
Flow Conditions ◽  
Dynamic Flow ◽  
Migration Process ◽  
Settlement Rate ◽  
Irregular Shapes ◽  
Water Conditions

Abstract Because of different compositions, physicochemical properties and shapes in nature of the microplastics (MPs), their migration process in the environment is very different, which makes it difficult to predict the behavior trajectory. This article mainly studies the sedimentation law of MPs under static and dynamic water conditions. Four kinds of materials, respectively polystyrene (PS), Polyamide (PA), polyethylene terephthalate (PET) and polyvinyl chloride (PVC), about 1230 MP particles with irregular shapes are selected for sedimentation experiments. They are divided into three shapes: near-sphere, polygonal ellipsoid and fragment. The experimental results show that the near-sphere MPs settled at the fastest rate, followed by the polygonal ellipsoid MPs, and the fragmented MPs settled at the slowest rate. By the force analysis of MPs in the settlement process, and the theoretical formula of MP settlement rate with their shape, particle size, density and water density are obtained, which has better fitting degree.

scholarly journals Fundamental Study on Properties of Small Particle Size Porous Concrete

2014 ◽  
Vol 12 (1) ◽  
pp. 24-33 ◽  
Author(s):  
Shigemitsu Hatanaka ◽  
Naoki Mishima ◽  
Akihiro Maegawa ◽  
Eisuke Sakamoto
Keyword(s):  
Particle Size ◽  
Small Particle ◽  
Small Particle Size ◽  
Fundamental Study ◽  
Porous Concrete

scholarly journals Theoretical and Experimental Investigation of Characteristics of Single Fracture Stress-Seepage Coupling considering Microroughness

2017 ◽  
Vol 2017 ◽  
pp. 1-12
Author(s):  
Shengtong Di ◽  
Chao Jia ◽  
Weiguo Qiao ◽  
Weijiang Yu ◽  
Kang Li
Keyword(s):  
Particle Size ◽  
Laboratory Test ◽  
Permeability Coefficient ◽  
Fracture Stress ◽  
Rock Fracture ◽  
Test System ◽  
Theoretical Formula ◽  
Single Fracture ◽  
Hydraulic Pressure ◽  
Hydraulic Aperture

Based on the results of the test among the joint roughness coefficient (JRC) of rock fracture, mechanical aperture, and hydraulic aperture proposed by Barton, this paper deduces and proposes a permeability coefficient formula of single fracture stress-seepage coupling considering microroughness by the introduction of effect variables considering the microparticle size and structural morphology of facture surface. Quasi-sandstone fracture of different particle size is made by the laboratory test, and the respective modification is made on the coupled shear-seepage test system of JAW-600 rock. Under this condition, the laboratory test of stress-seepage coupling of fracture of different particle size is carried out. The test results show that, for the different particle-sized fracture surface of the same JRC, the permeability coefficient is different, which means the smaller particle size, the smaller permeability coefficient, and the larger particle size, the larger permeability coefficient; with the increase of cranny hydraulic pressure, the permeability coefficient increases exponentially, and under the same cranny hydraulic pressure, there is relation of power function between the permeability coefficient and normal stress. Meanwhile, according to the theoretical formula, the microroughness coefficient of the fractures with different particle size is obtained by the calculation, and its accuracy and validity are verified by experiments. The theoretical verification values are in good agreement with the measured values.

Sorption between microorganisms and clay minerals as determined by the electrical sensing zone particle analyzer

1968 ◽  
Vol 14 (4) ◽  
pp. 299-307 ◽  
Author(s):  
T. Santoro ◽  
G. Stotzky
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Clay Minerals ◽  
Benzalkonium Chloride ◽  
Yeast Cells ◽  
Monovalent Cations ◽  
Natural Habitats ◽  
Electrical Sensing ◽  
Trivalent Cations ◽  
Electronic Particle Counter

Sorption between microbial cells and clay minerals was determined by measuring changes in particle size distribution with an electronic particle counter. Sorption increased as the valency of the cations present on the clay and in the suspending electrolyte increased. Neither the size, motility, or Gram reaction of bacteria nor the size of the clay appeared to influence sorption. Sorption occurred between bacteria and montmorillonite homoionic to monovalent cations only at pH 2 to 4, but did not occur at any pH with yeast cells, which sorbed only in the presence of trivalent cations. Heat-killed cells of yeast lost their ability to sorb, whereas cells killed with benzalkonium chloride did not. The possible implications of these results in sorption of microorganisms in natural habitats are discussed.

scholarly journals Influence of Durum Wheat Bran Particle Size on Phytochemical Content and on Leavened Bread Baking Quality

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 489
Author(s):  
Nabeel T. Alzuwaid ◽  
Denise Pleming ◽  
Christopher M. Fellows ◽  
Barbara Laddomada ◽  
Mike Sissons
Keyword(s):  
Particle Size ◽  
Durum Wheat ◽  
Wheat Bran ◽  
Animal Feed ◽  
Bread Quality ◽  
Total Phenolic ◽  
Loaf Volume ◽  
Particle Size Range ◽  
Minimal Impact ◽  
Phytochemical Content

Wheat bran is a conventional by-product of the wheat milling industry mainly used for animal feed. It is a rich and inexpensive source of phytonutrients, so is in demand for fibre-rich food products but creates quality issues when incorporated into bread. The purpose of this study was to characterize the physicochemical properties and phytochemical composition of different size durum bran fractions and show how they impact bread quality. Durum wheat (Triticum durum Desf.) was milled to create a coarse bran fraction (CB), which was further ground into a finer fraction (FB) which was sieved using four screens with apertures 425, 315, 250, 180, and <180 µm to create a particle size range of 1497 to 115 µm. All fractions contained phytosterol with highest in the 180 and FB, while total phenolic acids and antioxidant capacity was highest in CB and 425. Use of the fractions in a leavened common wheat (T. aestivum L.) bread formula at 10% incorporation negatively impacted bread loaf volume, colour, and texture compared to standard loaves, with CB having the least impact. Results suggest that to combine the highest phytochemical content with minimal impact on bread quality, bran particle size should be considered, with CB being the best choice.

scholarly journals A permeability model of packed particles material based on 2-dimensional fractal gradation spectrum

2021 ◽  
pp. 153-153
Author(s):  
Fan Zuo ◽  
Junqing Liu ◽  
Meng Li ◽  
Chao Liu
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Theoretical Formula ◽  
Empirical Formulas ◽  
Pore Characteristics ◽  
Permeability Model ◽  
Permeability Property ◽  
Particle Accumulation ◽  
Conventional Models

The permeability property of a packed particles material has been caught much attention, it depends upon its pore characteristics caused by the particle accumulation, but the current empirical formulas and the permeable theory could not reveal the effect of the particle accumulation thoroughly. In this paper, a theoretical formula is derived, and the fractal gradation spectrum is adopted to confirm the particle size distribution (PSD), furthermore the pore feature is determined by the particle size and accumulation features, finally a permeability model of the packed particles material is established. In this model, the effect of PSD on pore features is estimated more thoroughly than those in conventional models, and the calculated results are more accurate and verified experimentally.

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