Diffusion Modeling in Compacted Bentonite Based on Modified Gouy-Chapman Model

2014 ◽  
Vol 1665 ◽  
pp. 123-129 ◽  
Author(s):  
Kenji Yotsuji ◽  
Yukio Tachi ◽  
Yuichirou Nishimaki
Keyword(s):  
Current Model ◽  
Effective Diffusivity ◽  
Volume Effect ◽  
Complex Species ◽  
Compacted Bentonite ◽  
Multivalent Ions ◽  
Wide Range ◽  
Energy Of Hydration ◽  
Poisson Boltzmann ◽  
And Diffusion

ABSTRACTThe integrated sorption and diffusion (ISD) model has been developed to quantify radionuclide transport in compacted bentonite. The current ISD model, based on averaged pore aperture and the Gouy-Chapman electric double layer (EDL) theory can quantitatively account for diffusion of monovalent cations and anions under a wide range of conditions (e.g., salinity, bentonite density). To improve the applicability of the current ISD model for multivalent ions and complex species, the excluded volume effect and the dielectric saturation effect were incorporated into the current model, and the modified Poisson-Boltzmann equations were numerically solved. These modified models had little effect on the calculation of effective diffusivity of Sr2+/Cs+/I−. On the other hand, the model, modified considering the effective electric charge of hydrated ions, calculated using the Gibbs free energy of hydration, agreed well with the diffusion data including those of Sr2+.

scholarly journals Multiparametric MRI Texture Analysis in Prediction of Glioma Biomarker Status: Added Value of MR Diffusion

2021 ◽  
Author(s):  
Shingo Kihira ◽  
Nadejda Tsankova ◽  
Adam Bauer ◽  
Yu Sakai ◽  
Keon Mahmoudi ◽  
...  
Keyword(s):  
Texture Analysis ◽  
Diffusion Mri ◽  
Test Group ◽  
Multiparametric Mri ◽  
Added Value ◽  
Conventional Mri ◽  
Mri Features ◽  
Wide Range ◽  
Mr Diffusion ◽  
And Diffusion

Abstract Background Early identification of glioma molecular phenotypes can lead to understanding of patient prognosis and treatment guidance. We aimed to develop a multiparametric MRI texture analysis model using a combination of conventional and diffusion MRI to predict a wide range of biomarkers in patients with glioma. Methods In this retrospective study, patients were included if they 1) had diagnosis of gliomas with known IDH1, EGFR, MGMT, ATRX, TP53 and PTEN status from surgical pathology and 2) had preoperative MRI including FLAIR, T1c+ and diffusion for radiomic texture analysis. Statistical analysis included logistic regression and receiver-operating characteristic (ROC) curve analysis to determine the optimal model for predicting glioma biomarkers. A comparative analysis between ROCs (conventional only vs. conventional + diffusion) was performed. Results From a total of 111 patients included, 91 (82%) were categorized to training and 20 (18%) to test datasets. Constructed cross-validated model using a combination of texture features from conventional and diffusion MRI resulted in overall AUC/accuracy of 1/79% for IDH1, 0.99/80% for ATRX, 0.79/67% for MGMT, and 0.77/66% for EGFR. The addition of diffusion data to conventional MRI features significantly (p<0.05) increased predictive performance for IDH1, MGMT and ATRX. The overall accuracy of the final model in predicting biomarkers in the test group was 80% (IDH1), 70% (ATRX), 70% (MGMT) and 75% (EGFR). Conclusion Addition of MR diffusion to conventional MRI features provides added diagnostic value in preoperative determination of IDH1, MGMT, and ATRX in patients with glioma.

Measurement of Soil Suction and Soil-Water Characteristics of Bentonite-Sand Mixtures

2010 ◽  
Author(s):  
Pan Hu ◽  
Qing Yang ◽  
Maotian Luan
Keyword(s):  
Soil Water ◽  
Vapor Phase ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Phase Method ◽  
Soil Suction ◽  
Compacted Bentonite ◽  
Water Characteristics ◽  
Wide Range ◽  
High Level

The soil-water characteristic curve (SWCC) is a widely used experimental means for assessing fundamental properties of unsaturated soils for a wide range of soil suction values. The study of SWCC is helpful because some properties of unsaturated soils can be predicted from it. Nowadays, much attention has been paid to the behaviours of highly compacted bentonite-sand mixtures used in engineering barriers for high level radioactive nuclear waste disposal. It is very important to study the various performances of bentonite-sand mixtures in order to insure the safety of high-level radioactive waste (HLW) repository. After an introduction to vapor phase method and osmotic technique, a laboratory study has been carried out on compacted bentonite-sand mixtures. The SWCC of bentonite-sand mixtures has been obtained and analyzed. The results show that the vapor phase method and osmotic technique is suitable to the unsaturated soils with high and low suction.

A review of the Afrotropical sand tampan, Ornithodoros savignyi: a complex species.

2021 ◽  
Vol 16 (036) ◽  
Author(s):  
Roxanne Albertha Charles
Keyword(s):  
Species Complex ◽  
Single Species ◽  
Biological Molecules ◽  
Soft Tick ◽  
Complex Species ◽  
Lake Chad ◽  
Ornithodoros Savignyi ◽  
Morphological Studies ◽  
Biological Studies ◽  
Wide Range

Abstract The sand tampan, Ornithodoros savignyi (Audouin, 1827), is an economically important soft tick of the Afrotropics parasitising a wide range of livestock and humans. These ticks are known to inflict painful bites which may be fatal in susceptible hosts. Historically thought to be a single species, Ornithodoros savignyi is now considered to be a complex of four tick subspecies based on molecular and morphological studies. They include Ornithodoros (Ornithodoros) kalahariensis, O. (O.) pavimentosus, O. (O.) noorsveldensis and O. (O.) savignyi. As such there may be significant implications for previous biological studies conducted on this tick. Therefore, for the purposes of this review, sand tampan toxicosis and potentially useful biological molecules have been discussed for O. (O.) savignyi sensu lato since most reported work was based on ticks collected from the Kalahari and Lake Chad region. An overview of the host range and vector biology for the O. (O.) savignyi species complex will also be examined.

scholarly journals The Mixed Current Model of Nano-MOSFETs Considering the Effect of Horizontal and Vertical Electric Fields

2019 ◽  
Author(s):  
Heng-Sheng Huang ◽  
Ping-Ray Huang ◽  
Mu-Chun Wang ◽  
Shuang-Yuan Chen ◽  
Shea-Jue Wang ◽  
...  
Keyword(s):  
Electric Fields ◽  
Current Model ◽  
Atomic Layer ◽  
Diffusion Current ◽  
Electrical Performance ◽  
Short Channel ◽  
Drive Current ◽  
Layer Deposition ◽  
And Diffusion ◽  
Better Than

A novel drive current model covering the effects of source/drain voltage (VDS) and gate voltage (VGS) and incorporating drift and diffusion current on the surface channel at the nano-node level, especially beyond 28nm node is presented. The effect of the diffusion current added is more satisfactory to describe the behavior of the drive current in nano-node MOSFETs, fabricated with the atomic-layer-deposition (ALD) technology. This breakthrough in model establishment can expose the long and short channel devices together. Introducing the variables of VDS and VGS, the mixed current model more effectively and meaningfully demonstrates the drive current of MOSFETs under the operation of horizontal, vertical, or mixed electrical field. In comparison between the simulation and experimental consequences, the electrical performance is impressive. The error between both is less than 1%, better than the empirical adjustment to issue a set of drive current models.

scholarly journals Enhancing the Supply Chain in Organisations

2014 ◽  
pp. 156-171
Author(s):  
M. Reza Hosseini ◽  
Nicholas Chileshe ◽  
Raufdeen Rameezdeen ◽  
Steffen Lehmann
Keyword(s):  
Supply Chain ◽  
Supply Chains ◽  
Reverse Logistics ◽  
Adoption And Implementation ◽  
Wide Range ◽  
Adoption And Diffusion ◽  
And Diffusion ◽  
Lack Of Knowledge

Reverse Logistics (RL) is an innovation able to bring about immense benefits for organisations in a wide range of industries through enhancing the performance of supply chain procedures. Yet, evidence demonstrates that RL has remained unexploited mainly due to the lack of knowledge about its benefits, enablers, and major aspects of its adoption and implementation. In this context, promoting the adoption and diffusion of RL into the supply chain of organisations has been recommended frequently. This chapter provides a response to such need by (1) explaining the phenomenon and dispelling the confusions surrounding the RL concept, (2) clarifying the major drivers and barriers of RL and highlighting the role it can play in enhancing the performance of conventional supply chains; in addition, (3) the chapter intends to demystify the major aspects associated with implementing RL in organisations. The chapter also aims at familiarising potential readers with the major references available in the field.

scholarly journals Molecular Modeling Investigations of Sorption and Diffusion of Small Molecules in Glassy Polymers

Membranes ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 98 ◽  
Author(s):  
Niki Vergadou ◽  
Doros N. Theodorou
Keyword(s):  
Small Molecules ◽  
Molecular Simulation ◽  
Glassy Polymer ◽  
Polymeric Materials ◽  
Gas Separations ◽  
Polymeric Systems ◽  
Wide Range ◽  
Multiscale Problem ◽  
Polymer Configurations ◽  
And Diffusion

With a wide range of applications, from energy and environmental engineering, such as in gas separations and water purification, to biomedical engineering and packaging, glassy polymeric materials remain in the core of novel membrane and state-of the art barrier technologies. This review focuses on molecular simulation methodologies implemented for the study of sorption and diffusion of small molecules in dense glassy polymeric systems. Basic concepts are introduced and systematic methods for the generation of realistic polymer configurations are briefly presented. Challenges related to the long length and time scale phenomena that govern the permeation process in the glassy polymer matrix are described and molecular simulation approaches developed to address the multiscale problem at hand are discussed.

scholarly journals A further note upon "inter-traction."

1926 ◽  
Vol 112 (760) ◽  
pp. 213-214
Keyword(s):  
Specific Gravity ◽  
Interfacial Tension ◽  
Simple Technique ◽  
Cell Compartments ◽  
Previous Communication ◽  
Wide Range ◽  
And Diffusion ◽  
Adjoining Cell

I pointed out in a previous communication that a mixture of fluids can be brought about not only by the operations of mechanical convection and diffusion, but also by the impulsion of a force which can very rapidly carry down a lighter overlying fluid into a heavier underlying fluid in the form of characteristic pseudopodial streamers, conveying at the same time the heavier underlying fluid into the lighter superjacent fluid in the form of a palisade of ascending streams. I have ventured to call the agency by which this reciprocal instreaming is produced:― inter-traction . These phenomena which I described as occuring when salt, and also sugar, solutions brought into contract with albuminous solutionscan, as Schoneboom showed, be obtained also with a very wide range of substances; and they have been ascribed by him to the operations of negative interfacial tension, and identified with phenomena theoretically anticipated by Clerk-Maxwell. Adam and Jessop, in a further communication, have insisted that the pseudopodial streaming is attributable to operations of diffusion and resulting changes in specific gravity, and they have stressed the point that the characteristic appearances can be obtained only when the lighter is superposed upon the heavier fluid, and not when the fluids are disposed side by side. In view of the fact that the conclusion that horizontal streaming cannot be obtained rests only upon experiments conducted by filling fluids of different specific gravity into adjoining cell compartments, and then removing the dividing wall, it seemed desirable to try for horizantal inter-traction with a technique which would get rid of the complication of the heavier fluid sinking to the bottom and the lighter going to the top of the vessel, and would allow of more accurate and deliberate observation. The quite simple technique now to be described satisfies these desiderata.

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