scholarly journals Factors affecting transport of bacterial cells in porous media

1992 ◽  
Author(s):  
A.L. Mills ◽  
J.S. Herman ◽  
G.M. Hornberger
Keyword(s):  
Porous Media ◽  
Bacterial Cells ◽  
Factors Affecting

scholarly journals Factors affecting transport of bacterial cells in porous media

1990 ◽  
Author(s):  
A Mills ◽  
J Herman ◽  
G Hornberger
Keyword(s):  
Porous Media ◽  
Bacterial Cells ◽  
Factors Affecting

Microbial dispersal throgh dead-end cavities

2021 ◽  
Author(s):  
David Scheidweiler ◽  
Ankur Deep Bordoloi ◽  
Pietro de Anna
Keyword(s):  
Porous Media ◽  
Time Lapse ◽  
Breakthrough Curves ◽  
Bacterial Cells ◽  
Dispersal Patterns ◽  
Microbial Life ◽  
Sedimentary Environments ◽  
Escherichia Coli Cells ◽  
Dead End

<p>Predicting dispersal patterns is important to understand microbial life in porous media as soils and sedimentary environments. We studied active and passive dispersal of bacterial cells in porous media characterized by two main pore features: fast channels and dead-end cavities. We combined experiments with microfluidic devices and time-lapse microscopy to track individual bacterial trajectories and measure the breakthrough curves and pore scale bacterial abundance. Escherichia coli cells dispersed more efficiently than the non-motile mutants showing a different retention in the dead-end pores. Our findings highlight the role of diffusion dominated dead-end pores on the dispersal of microorganisms in porous media.</p>

scholarly journals The Hydrodynamic Dispersion Characteristics of Coral Sands

2019 ◽  
Vol 7 (9) ◽  
pp. 291 ◽  
Author(s):  
Xiang Cui ◽  
Changqi Zhu ◽  
Mingjian Hu ◽  
Xinzhi Wang ◽  
Haifeng Liu
Keyword(s):  
Particle Size ◽  
Porous Media ◽  
Flow Velocity ◽  
Molecular Diffusion ◽  
Dispersion Coefficient ◽  
Hydrodynamic Dispersion ◽  
Dispersion Characteristics ◽  
Factors Affecting ◽  
Mechanical Dispersion ◽  
Freshwater Aquifers

Dispersion characteristics are important factors affecting groundwater solute transport in porous media. In marine environments, solute dispersion leads to the formation of freshwater aquifers under islands. In this study, a series of model tests were designed to explore the relationship between the dispersion characteristics of solute in calcareous sands and the particle size, degree of compactness, and gradation of porous media, with a discussion of the types of dispersion mechanisms in coral sands. It was found that the particle size of coral sands was an important parameter affecting the dispersion coefficient, with the dispersion coefficient increasing with particle size. Gradation was also an important factor affecting the dispersion coefficient of coral sands, with the dispersion coefficient increasing with increasing d10. The dispersion coefficient of coral sands decreased approximately linearly with increasing compactness. The rate of decrease was −0.7244 for single-grained coral sands of particle size 0.25–0.5 mm. When the solute concentrations and particle sizes increased, the limiting concentration gradients at equilibrium decreased. In this study, based on the relative weights of molecular diffusion versus mechanical dispersion under different flow velocity conditions, the dispersion mechanisms were classified into five types, and for each type, a corresponding flow velocity limit was derived.

Factors affecting adsorption of Azospirillum brasilense Cd to root hairs as compared with root surface of wheat

1989 ◽  
Vol 35 (10) ◽  
pp. 936-944 ◽  
Author(s):  
Yoav Bashan ◽  
Hanna Levanony
Keyword(s):  
Azospirillum Brasilense ◽  
Root Hairs ◽  
Growth Conditions ◽  
Root Surface ◽  
Logarithmic Phase ◽  
Bacterial Cells ◽  
Beneficial Bacteria ◽  
Factors Affecting ◽  
Associative Bacteria ◽  
Bacterial Adsorption

Electron microscopy of wheat (Triticum aestivum) roots inoculated with Azospirillum brasilense Cd revealed massive adsorption of bacterial cells to the root surface and less adsorption to root hairs. Quantitative analysis of A. brasilense Cd adsorption to root surface and to root hairs, confirmed qualitatively by light microscopy observations, revealed a bacterial adsorption ratio of 5 (+2): 1 (root surface: root hairs). Extreme bacterial adsorption ratios were recorded when bacteria were previously grown in the presence of KNO3 (27:1) or when bacterial cells were inoculated under hydroponic plant growth conditions (80:1). Adsorption of A. brasilense Cd to roots was directly related to the bacterial growth phase, with logarithmic phase cultures demonstrating a greater adsorption than stationary phase cultures. Adsorption to root hairs was dependent mainly on the number of root hairs developed under certain growth conditions. When very few root hairs had developed, most of the bacterial cells were adsorbed to the root surface. Factors such as starvation, bacteria grown in culture in the presence of KNO3, addition of several nutrients, and protease or NaEDTA treatments of bacterial cells before the adsorption assay decreased bacterial adsorption to root hairs. Other factors such as microaerophilic growth conditions, addition of several bacterial chemoattractants, and cellulase-treated root hairs enhanced bacterial adsorption. It is proposed that although A. brasilense Cd adsorbed to every part of the root system, more cells adsorbed to the root surface of wheat than to the root hairs.Key words: associative bacteria, Azospirillum, bacterial adsorption, beneficial bacteria, rhizosphere bacteria, root-hair colonization.

AN EXPERIMENTAL INVESTIGATION OF FACTORS AFFECTING ELASTIC WAVE VELOCITIES IN POROUS MEDIA

Geophysics ◽  
1958 ◽  
Vol 23 (3) ◽  
pp. 459-493 ◽  
Author(s):  
M. R. J. Wyllie ◽  
A. R. Gregory ◽  
G. H. F. Gardner
Keyword(s):  
Experimental Investigation ◽  
Porous Media ◽  
Oil And Gas ◽  
Velocity Data ◽  
Velocity Measurements ◽  
Factors Affecting ◽  
Gas Saturation ◽  
Wave Velocities ◽  
Time Average ◽  
Made In

An experimental investigation has been made of the factors which affect the velocity of vibratory signals in porous media. It is shown from the results of experiments carried out on appropriate natural and synthetic porous systems that the time‐average formula previously suggested by Wyllie, Gregory, and L. W. Gardner is of considerable utility. This formula states that [Formula: see text] where [Formula: see text] measured, [Formula: see text] in saturating liquid, [Formula: see text] in rock solid, and ϕ=volumetric porosity fraction. The effects are examined of differential compacting pressures on the applicability of this formula to consolidated and unconsolidated rocks. It is shown that the time‐average relationship cannot be applied to determine the total volumetric porosity of carbonate rocks which are vugular and fractured. In such rocks, paradoxically, this circumstance may be advantageous because of the lithological information that may be obtained from an appropriate combination of velocity and nuclear log data. The effects of oil and gas saturation on velocity have been examined experimentally and are found to be comparatively minor. The combination of velocity data with information from electric logs in order to locate zones of oil and gas saturation is shown to be generally valuable; this is particularly so when holes are drilled with oil‐base mud. Some discussion is given of the possible effects on velocity measurements of the relative wettability of rock surfaces by various liquids. Owing to instrumental limitations, it cannot necessarily be assumed that measurements made in the laboratory are directly applicable to the interpretation of velocity data obtained under field conditions.

Study of Selected Factors Affecting Hydrate-Based Carbon Dioxide Separation from Simulated Fuel Gas in Porous Media

2013 ◽  
Vol 27 (6) ◽  
pp. 3341-3348 ◽  
Author(s):  
Yongchen Song ◽  
Xiaojing Wang ◽  
Mingjun Yang ◽  
Lanlan Jiang ◽  
Yu Liu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Porous Media ◽  
Fuel Gas ◽  
Carbon Dioxide Separation ◽  
Factors Affecting ◽  
Simulated Fuel

Factors Affecting the Assembly of Carbon Nanostructures With Cells and Enzymes

2010 ◽  
Author(s):  
Sonal Mazumder ◽  
Suvojit Ghosh ◽  
Joseph O. Falkinham ◽  
Ishwar K. Puri
Keyword(s):  
Contact Angle ◽  
Stainless Steel ◽  
High Resolution ◽  
Surface Morphology ◽  
Carbon Nanostructures ◽  
Silicon Wafers ◽  
Flame Synthesis ◽  
Bacterial Cells ◽  
Factors Affecting ◽  
Nonpremixed Flame

Carbon nanostructures were synthesized and deposited through flame synthesis on stainless steel grids and foils, and on bare and ferrofluid-painted silicon wafers at different nonpremixed flame locations to produce hydrophobic surfaces. The hydrophobicity is characterized through the contact angle for water droplets placed on the surface. The surface morphology of the nanoparticles is obtained from high-resolution FESEM images. Following synthesis and deposition the adherence, activity, and stability of bacterial cells, antibodies, and enzymes on the carbon nanostructures can be studied.

Factors Affecting the Persistence of Salmonella During the Processing of Poultry

1989 ◽  
Vol 52 (11) ◽  
pp. 829-832 ◽  
Author(s):  
H. S. LILLARD
Keyword(s):  
Electron Microscopy ◽  
Cell Suspension ◽  
Significant Role ◽  
Bacterial Cell ◽  
Water Immersion ◽  
False Negative ◽  
Water Film ◽  
Bacterial Cells ◽  
Factors Affecting ◽  
Bacterial Cell Suspension

Bacteria, including Salmonella, have been shown to attach firmly to poultry skin and meat. Neither fimbriae, flagella, nor electrostatic attraction seem to play a significant role in the mechanism of attachment. Bacterial cells (95%) were shown to be initially entrapped in a water film on the skin, then to migrate to the skin with prolonged immersion in a bacterial cell suspension. Using electron microscopy it was shown that bacteria appear to be entrapped in ridges and crevices which become more pronounced in the skin and muscle following water immersion. This may make bacteria on carcasses inaccessible to bactericides. It was shown that bacteria are firmly attached to poultry skin before broilers arrive at the plant and that high numbers are still recovered after 40 consecutive whole carcass rinses of a single carcass. It was further shown that Salmonella are not always recovered in the first whole carcass rinse and that this method of sampling could result in false negative reports for Salmonella incidence.

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