Evaluation of substrate uptake by microbial film in a gel-like medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Substrate Uptake ◽  
Limited Region ◽  
Diffusion Limited ◽  
Incremental Value ◽  
Microbial Film ◽  
C And N ◽  
The Relationship ◽  
Kinetics Of ◽  
And Diffusion ◽  
Large Diffusion

Mathematical model was developed to demonstrates the predominantly reaction controlled region and diffusion limited region for p 3 with high or large diffusion in this case, but when p = 0.3 the chemical reaction and diffusion onset occurred. The model developed illustrates the relationship between K₃C* and N/Nmax for various incremental steps of K2 L. The result obtained reveals that increase in K3C* resulted to an increase in N/ Nmax until an optimum value of N/Nmax was achieved after then the values remain constant with incremental value on K3C*. The Kinetics of substrate is dependent of K3C* as well as K2L values of the system, which in overall influence the substrate uptake by microbial film in gel- like medium.

Influence of Electrolytes and Humic Acid on Aggregation Behavior of C60 Nanoparticles in Aquatic System

2013 ◽  
Vol 448-453 ◽  
pp. 48-51
Author(s):  
Hua Fang ◽  
Bing Bing Shen ◽  
Yu Xin Sun ◽  
Yuan Wang ◽  
Ji Lai Lu
Keyword(s):  
Humic Acid ◽  
Colloidal Stability ◽  
Dlvo Theory ◽  
Aquatic Environments ◽  
Aggregation Kinetics ◽  
Time Resolved ◽  
Diffusion Limited ◽  
Wide Range ◽  
Kinetics Of ◽  
And Diffusion

The aggregation kinetics of C60 nanoparticles have been investigated over a wide range of monovalent and divalent electrolyte concentrations by employing time-resolved dynamic light scattering (DLS). The results showed that the presence of electrolyte made a dramatic decrease in the surface zeta potential and increase in the particle size. The aggregation kinetics of C60 nanoparticles exhibited reaction-limited and diffusion-limited regimes, which was found to be consistent with the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability. The critical coagulation concentration (CCC) values of C60 nanoparticles were estimated as 321mM Na+, 295mM K+, 9.6mM Ca2+and 6.7mM Mg2+, which were far higher than the electrolyte concentrations in natural water. The enhanced C60 stability in the presence of humic acid was attributable to steric repulsion. Therefore C60 nanoparticles can be relatively stable in typical aquatic environments.

Fractal Concepts And Aggregation Of Iron Oxides

1990 ◽  
Vol 180 ◽  
Author(s):  
R. Amal ◽  
J.A. Raper ◽  
T.D. Waite
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Iron Oxides ◽  
Aggregate Size ◽  
Fractal Dimensions ◽  
Aggregation Kinetics ◽  
Diffusion Limited ◽  
Scattering Measurements ◽  
The Relationship ◽  
Kinetics Of

ABSTRACTThe modelling of the aggregation kinetics of iron oxides has been succesful in predicting the increase in aggregate size as determined by dynamic light scattering measurements. The aggregates were found to exhibit fractal behaviour with fractal dimensions obtained from the scattering exponent in static light scattering studies dependent on the aggregation mechanism and ranging from 2.3 for rapid (diffusion limited) to 2.8 for slow (reaction limited) aggregation. Polydispersity and restructuring of aggregates were found not to affect the relationship between scattering exponent and aggregate fractal dimension. Excellent correspondence over a range of temperatures and ionic strengths has been obtained between results of sizing experiments using dynamic light scattering and sizes predicted using a modified Smoluchowski model incorporating fractal dimensions.

scholarly journals Investigation into mechanisms and kinetics of asphaltene aggregation in toluene/n-hexane mixtures

2019 ◽  
Vol 17 (2) ◽  
pp. 457-466
Author(s):  
Bahram Soltani Soulgani ◽  
Fatemeh Reisi ◽  
Fatemeh Norouzi
Keyword(s):  
Image Processing ◽  
Fractal Theory ◽  
Particle Growth ◽  
Force Balance ◽  
Asphaltene Precipitation ◽  
Diffusion Limited Aggregation ◽  
Model Calculations ◽  
Diffusion Limited ◽  
Kinetics Of ◽  
And Diffusion

Abstract Determining the rate of asphaltene particle growth is one of the main problems in modeling of asphaltene precipitation and deposition. In this paper, the kinetics of asphaltene aggregation under different precipitant concentrations have been studied. The image processing method was performed on the digital photographs that were taken by a microscope as a function of time to determine the asphaltene aggregation growth mechanisms. The results of image processing by MATLAB software revealed that the growth of asphaltene aggregates is strongly a function of time. Different regions could be recognized during asphaltene particle growth including reaction- and diffusion-limited aggregation followed by reaching the maximum asphaltene aggregate size and start of asphaltene settling and the final equilibrium. Modeling has been carried out to predict the growth of asphaltene particle size based on the fractal theory. General equations have been developed for kinetics of asphaltene aggregation for reaction-limited aggregation and diffusion-limited aggregation. The maximum size of asphaltene aggregates and settling time were modeled by using force balance, acting on asphaltene particles. Results of modeling show a good agreement between laboratory measurements and model calculations.

Low Energy Ion Bombardment and Microstructural Evolution in Thin Films

1989 ◽  
Vol 157 ◽  
Author(s):  
Chih M. Yang ◽  
Harry A. Atwater
Keyword(s):  
Thin Films ◽  
Ion Bombardment ◽  
Island Growth ◽  
New Approach ◽  
Enhanced Diffusion ◽  
Rate Laws ◽  
Island Evolution ◽  
Diffusion Limited ◽  
Kinetics Of ◽  
And Diffusion

ABSTRACTA new approach to modeling the evolution of islands in thin films by growth and coarsening during ion bombardment is described. Solution of a continuity equation and matter conservation relation, coupled with interface-limited and diffusion-limited rate laws for island growth and coarsening allows the kinetics of island evolution to be modeled. Results from the model indicate distinct kinetic paths for island evolution during ion bombardment as a result of growth, enhanced diffusion, island dissociation and monomer sputtering.

Diffusion and Adoption of Corruption in Developing Economies: Evidence from Ghana

2018 ◽  
Vol 6 (6) ◽  
pp. 21
Author(s):  
Solomon A. Keelson ◽  
Thomas Cudjoe ◽  
Manteaw Joy Tenkoran
Keyword(s):  
Social Values ◽  
Developing Economies ◽  
Policy Formulation ◽  
Institutional Factors ◽  
Developing Economy ◽  
Theoretical Underpinning ◽  
Institutional Failure ◽  
The Social ◽  
The Relationship ◽  
And Diffusion

The present study investigates diffusion and adoption of corruption and factors that influence the rate of adoption of corruption in Ghana. In the current study, the diffusion and adoption of corruption and the factors that influence the speed with which corruption spreads in society is examined within Ghana as a developing economy. Data from public sector workers in Ghana are used to conduct the study. Our findings based on the results from One Sample T-Test suggest that corruption is perceived to be high in Ghana and diffusion and adoption of corruption has witnessed appreciative increases. Social and institutional factors seem to have a larger influence on the rate of corruption adoption than other factors. These findings indicate the need for theoretical underpinning in policy formulation to face corruption by incorporating the relationship between the social values and institutional failure, as represented by the rate of corruption adoption in developing economies.

scholarly journals The Diffusion Mechanism of Megaproject Citizenship Behavior: The Role of Institutional Isomorphism

2021 ◽  
Vol 13 (15) ◽  
pp. 8123
Author(s):  
Delei Yang ◽  
Jun Zhu ◽  
Qingbin Cui ◽  
Qinghua He ◽  
Xian Zheng
Keyword(s):  
Structural Equation ◽  
Diffusion Mechanism ◽  
Vital Role ◽  
Citizenship Behavior ◽  
Equation Modeling ◽  
Positive Effects ◽  
Diffusion Limited ◽  
The Relationship ◽  
Mimetic Isomorphism

Megaproject citizenship behavior (MCB) has been confirmed to a play vital role on megaproject performance. Although current research has argued that institution elements have had an impact on MCB diffusion, limited studies have empirically investigated the distinct effectiveness of various institution elements on driving MCB’s widespread diffusion in construction megaprojects. Based on institution theory, this study proposes a theoretical model comprising institutional elements (i.e., normative and mimetic isomorphism), owner’s support, relationship-based trust, and their effect or impact on MCB’s diffusion. Based on 171 industrial questionnaires collected from managers of contractors and designers in megaprojects. Partial least squares structural equation modeling (PLS-SEM) was used to validate the established model. The results indicated that both normative and mimetic isomorphism have positive effects on facilitating MCB diffusion, and owner’s support has shown partial mediation in promoting MCB diffusion through normative isomorphism, as well as full mediation in the promoting of MCB diffusion through mimetic isomorphism. Meanwhile, relationship-based trust exerts a positive moderating effect on the relationship between mimetic isomorphism and MCB. This study extends current literature on driving MCB diffusion from the perspective of institutional theory, contributing by providing four implications for megaprojects managers to “buy in” more extensive MCB.

scholarly journals Biosorption and Diffusion Modeling of Pb(II) by Malt Bagasse

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Klaiani B. Fontana ◽  
Giane Gonçalves Lenzi ◽  
Erica R. L. R. Watanabe ◽  
Ervin Kaminski Lenzi ◽  
Juliana A. M. T. Pietrobelli ◽  
...  
Keyword(s):  
Sorption Process ◽  
Isotherm Models ◽  
Diffusion Modeling ◽  
Biosorption Capacity ◽  
Kinetic And Thermodynamic Parameters ◽  
Pseudo Second Order ◽  
Ph Optimization ◽  
Kinetics Of ◽  
And Diffusion

The removal of Pb(II) from water by biosorption processes onto malt bagasse was investigated and the kinetic and thermodynamic parameters were obtained; additionally a diffusion modeling was proposed. The characterization of malt bagasse was performed by FTIR and SEM/EDS. The experiments were conducted in batch system and an experimental design based response surface methodology was applied for agitation speed and pH optimization. The kinetics of biosorption followed pseudo-second-order model and the temperature of the process affected the biosorption capacity. Isotherm models of Langmuir, Freundlich, and Elovich were applied and the Langmuir model showed better fit and the estimated biosorption capacity was 29.1 mg g−1. The negative values obtained for ΔG° and positive values of ΔH° confirm, respectively, the spontaneous and endothermic nature of the process. The diffusion modeling was performed based on experiments in the absence of agitation to investigate the influence of the biosorbent on the sorption process of Pb(II) ions.

A large portion of the astrocyte proteome is dedicated to perivascular endfeet, including critical components of the electron transport chain

2021 ◽  
pp. 0271678X2110041
Author(s):  
Jesse A Stokum ◽  
Bosung Shim ◽  
Weiliang Huang ◽  
Maureen Kane ◽  
Jesse A Smith ◽  
...  
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Glycogen Storage ◽  
Subcellular Compartment ◽  
Diffusion Limited ◽  
Transport Chain ◽  
Critical Components ◽  
And Diffusion ◽  
Ubiquitous Presence ◽  
Astrocyte Endfeet

The perivascular astrocyte endfoot is a specialized and diffusion-limited subcellular compartment that fully ensheathes the cerebral vasculature. Despite their ubiquitous presence, a detailed understanding of endfoot physiology remains elusive, in part due to a limited understanding of the proteins that distinguish the endfoot from the greater astrocyte body. Here, we developed a technique to isolate astrocyte endfeet from brain tissue, which was used to study the endfoot proteome in comparison to the astrocyte somata. In our approach, brain microvessels, which retain their endfoot processes, were isolated from mouse brain and dissociated, whereupon endfeet were recovered using an antibody-based column astrocyte isolation kit. Our findings expand the known set of proteins enriched at the endfoot from 10 to 516, which comprised more than 1/5th of the entire detected astrocyte proteome. Numerous critical electron transport chain proteins were expressed only at the endfeet, while enzymes involved in glycogen storage were distributed to the somata, indicating subcellular metabolic compartmentalization. The endfoot proteome also included numerous proteins that, while known to have important contributions to blood-brain barrier function, were not previously known to localize to the endfoot. Our findings highlight the importance of the endfoot and suggest new routes of investigation into endfoot function.

The Formation of Cu3Si from Cu/a-Si Multilayers

1997 ◽  
Vol 481 ◽  
Author(s):  
R. R. Chromik ◽  
W. K. Neils ◽  
E. J. Cotts
Keyword(s):  
Diffusion Couples ◽  
X Ray Diffraction ◽  
Limited Growth ◽  
Scanning Calorimetry ◽  
Individual Layer ◽  
Diffusion Limited ◽  
Reaction Constant ◽  
Multilayered Composites ◽  
Reaction Constants ◽  
Kinetics Of

ABSTRACTThe kinetics of the formation of Cu3Si in Cu/a-Si diffusion couples have been investigated by means of differential scanning calorimetry and x-ray diffraction. Multilayered composites of average stoichiometry Cu3Si were prepared by sputter deposition with individual layer thicknesses varying in different samples between 2 and 100 nm. We observed diffusion limited growth of Cu3 Si upon annealing these diffusion couples below 500 K. Reaction constants were measured for a temperature range of 455 to 495 K for thicknesses of growing Cu3Si between 2.6 and 80 nm. The temperature dependence of the reaction constant, k2, was characterized as k2 = k0 exp(− Ea/kbT) with activation energy, Ea = 1.0 eV/atom and pre-factor, k0 = 1.9×10−3 cm2/s.

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