Transport Mechanisms in Electrokinetic Nanoscale Channels

2004 ◽  
Author(s):  
Sumita Pennathur ◽  
Juan G. Santiago
Keyword(s):  
Field Theory ◽  
Parametric Study ◽  
Nanometer Scale ◽  
Transport Mechanisms ◽  
Electrokinetic Transport ◽  
Zeta Potentials ◽  
Numerical Studies ◽  
Debye Layer ◽  
Model Predictions ◽  
Shape And Size

We investigate electrokinetic transport in nanometer-scale fluidic channels. Our study includes numerical studies of nanofluidic transport of both charged and uncharged analytes in conditions of finite Debye layer thickness and high zeta potentials. The models are based on continuum mass transport and field theory. We also perform an experimental parametric study using etched nanoscale channels. Experimental results agree with model predictions and show that bulk electrokinetic transport in nanoscale channels depends strongly on the shape and size of the EDL and on the effects of transverse electrophoretic migration.

Advancing conjugated polymers into nanometer-scale devices

2006 ◽  
Vol 78 (10) ◽  
pp. 1803-1822 ◽  
Author(s):  
Wenping Hu ◽  
Hiroshi Nakashima ◽  
Erjing Wang ◽  
Kazuaki Furukawa ◽  
Hongxiang Li ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Molecular Level ◽  
Nanometer Scale ◽  
Transport Mechanisms ◽  
Phenylene Ethynylene ◽  
Polymer Molecules ◽  
Polymer Electronics ◽  
End Groups

In this article, we review the possibility of combining conjugated polymers with nanometer-scale devices (nanodevices), in order to introduce the properties associated with conjugated polymers into such nanodevices. This approach envisages combining the highly topical disciplines of polymer electronics and nanoelectronics to engender a new subdirection of polymer nanoelectronics, which can serve as a tool to probe the behavior of polymer molecules at the nanometer/molecular level, and contribute to clarifying transport mechanisms in conjugated polymers. In this study, we exemplify this combination, using a family of linear and conjugated polymers, poly(p-phenylene-ethynylene)s (PPEs) with thiolacetate-functionalized end groups.

Processes of evaporation from vegetation of the uplands of Scotland

1987 ◽  
Vol 78 (4) ◽  
pp. 327-334 ◽  
Author(s):  
R. L. Hall
Keyword(s):  
Diffusion Theory ◽  
Coniferous Forest ◽  
Significant Proportion ◽  
Indigenous Species ◽  
Transport Mechanisms ◽  
Model Predictions ◽  
Process Studies ◽  
Series Of Experiments ◽  
High Altitude Grassland ◽  
Snow Precipitation

ABSTRACTThe results of a series of experiments to study the physical processes governing the evaporation from upland vegetation in Scotland, i.e. coniferous forest, heather and grass, are described. Particular attention is given to the interception process occurring in heather, one of the dominant indigenous species in Scottish upland catchments. Attention is also given to the interception of snow precipitation which in the Scottish uplands is a significant proportion of the total precipitation. A comparison of the parameters describing the efficiency of the transport process of water vapour for coniferous forest and heather indicates that the process is more efficient than predicted by classical diffusion theory: additional transport mechanisms are considered. A simple model, based upon the results of the process studies, was applied to data from the Monachyle catchment (Balquhidder) and the model predictions compared with observations. This study, in conjunction with recent results from the Balquhidder catchment experiment, illustrates the necessity of further investigations to give a fuller understanding of the evaporation from high altitude grassland.

scholarly journals Experimental and Numerical Studies on Thermally-Induced Slip Ratcheting on a Slope

2020 ◽  
Vol 6 (1) ◽  
pp. 5
Author(s):  
Sihyun Kim ◽  
Seunghee Kim ◽  
Jingtao Zhang ◽  
Ethan Druszkowski ◽  
Abdallah Sweidan
Keyword(s):  
Numerical Model ◽  
Parametric Study ◽  
Temperature Increase ◽  
Temperature Fluctuation ◽  
Structural Instability ◽  
Neutral Point ◽  
Thermally Induced ◽  
Temperature Changes ◽  
Numerical Studies ◽  
Mild Temperature

Mild temperature fluctuation of a material sitting on a slope may only cause a small slip, but a large number of the repeated temperature changes can amplify the magnitude of the overall slip and eventually bring an issue of structural instability. The slip accumulation starts from the minor magnitude and reaches the extensive level called “slip ratcheting”. Experimental evidence for such thermally-induced slip ratcheting is first provided in this work. It is implemented with an acryl sheet placed on an inclined wood with a mild angle; it is found that the temperature fluctuation of the acryl sheet causes the sheet to slide down gradually without any additional loading. The numerical model is then attempted to emulate the major findings of the experiments. From the simulation work, the location of a neutral point is found when the acryl plate is heated, and another neutral point is observed when cooled down. The shift of the neutral point appears to be a major reason for the unrecovered slip after a temperature increase and decrease cycle. Finally, a parametric study using the numerical model is carried out to examine which parameters play a major role in the development of residual slips.

scholarly journals Numerical Studies and Analyses on the Acidizing Process in Vug Carbonate Rocks

2021 ◽  
Vol 9 ◽  
Author(s):  
Cunqi Jia ◽  
Kamy Sepehrnoori ◽  
Haiyang Zhang ◽  
Jun Yao
Keyword(s):  
Acid Solution ◽  
Pore Volume ◽  
Parametric Study ◽  
Carbonate Rocks ◽  
Carbonate Rock ◽  
Hydraulic Behavior ◽  
Numerical Studies ◽  
Pass Through

A vug porosity system, in addition to a matrix, is also the target rocks for the acidizing. In this work, the acidizing process in two typical core-scale separate-vug porosity systems is studied in detail. Numerous cases are conducted to discuss a parametric study on the acidizing process and hydraulic behavior. Results indicate that the presence of vug reduces the pore volume of acid solution consumed to achieve a breakthrough, which is consistent with experimental observations. Increasing the vug diameter and porosity decreases pore volume to breakthrough both for a vugular carbonate rock and isolated vug carbonate rock. In comparison, the acid mass does not change a lot. Typical dissolution patterns can also be observed in the acidizing process when a vug exists. Compared to matrix dissolution patterns, the presence of vug induces wormhole to pass through the vug region.

Justification of Non-Dimensional Schemes and Identification of Parameters on Modelling Electrokinetic Transport Phenomena in Microchannels

2010 ◽  
Author(s):  
Zhanjie Shao ◽  
Gerry Schneider ◽  
Carolyn Ren
Keyword(s):  
Initial Conditions ◽  
Transport Phenomena ◽  
Concentration Field ◽  
Electrokinetic Transport ◽  
Dimensional Model ◽  
Applied Potential ◽  
Governing Equations ◽  
Numerical Studies ◽  
Electrokinetic Flows ◽  
On Chip

The electrokinetic transport phenomena are to be numerically studied based on cross-linked microchannel networks, which have been commonly employed for on-chip capillary electrophoresis applications. Applied potential field, flow field and concentration field should be solved to predict the species transport process under electrokinetic flows. Together with the well-designed channel geometry, a detailed physical model was firstly formulated through a series of governing equations and corresponding boundary/initial conditions, which was briefly re-presented from our previous publications. The emphasis of current work was to justify the simplest non-dimensional scheme and identify the most beneficial parameters so that an effective and simplified non-dimensional model was developed for numerical studies.

Peritoneal physicochemical transport mechanisms: Hypotheses, models and controversies

2021 ◽  
pp. 089686082110024
Author(s):  
Matthew B Wolf
Keyword(s):  
Lymph Flow ◽  
Time Varying ◽  
Transport Mechanisms ◽  
Mean Values ◽  
Intraperitoneal Pressure ◽  
Model Predictions ◽  
Time Varying Parameters ◽  
Transport Kinetic ◽  
The Mean ◽  
Parameter Values

This study answers criticisms by Waniewski et al. of the recent paper by Wolf on peritoneal transport kinetic models. Their criticisms centre on the accuracy of the data used for model fits, the hypothesis presented, which involves changes in glucose membrane parameters at high peritoneal glucose concentration and on the necessary techniques required to achieve accurate model parameter estimation. In response, this article shows that (1) the mean values previously captured from graphical depictions of Heimburger et al. are not different than those captured from the recent Waniewski et al. graphs, (2) a much simpler hypothesis is proposed, which centres on intraperitoneal pressure-induced lymph flow during the dialysis dwell and (3) the finding that the new model predictions, with only two constant parameter values, as estimated by the Powell algorithm, give a closer fit than the Waniewski model, which uses many time-varying parameters. The current findings again bring into question of the validity of their vasodilation hypothesis, leading to transient changes in capillary surface area during the dwell.

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