scholarly journals Estimating the Thermal Conductivities and Elastic Stiffness of Carbon Nanotubes as a Function of Tube Geometry

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Z. H. Zhang ◽  
N. Yu ◽  
W. H. Chao
Keyword(s):  
Experimental Data ◽  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Present Model ◽  
Elastic Stiffness ◽  
The Other ◽  
Microstructural Parameters ◽  
The Relationship ◽  
Tube Geometry ◽  
Thermal Conductivities

The thermal conductivities and elastic properties of carbon nanotubes (CNTs) are estimated by using the double-inclusion model, which is based on rigorous elasticity approach. The model regards a CNT as one inclusion (the inner cylindrical void) embedded in the other (the outer coaxial single-crystal graphite shell). The concept of homogenization is employed, and vital microstructural parameters, such as CNT diameter, length, and aspect ratio, are included in the present model. The relationship between microstructure and thermal conductivities and elastic stiffness of CNTs is quantitatively characterized. Our analytical results, benchmarked by experimental data, show that the thermal conductivities and elastic stiffness of CNTs are strongly dependent on the diameter of CNT with little dependence on the length of CNT.

Functional Nanodiamond Internalization Mechanisms and Kinetics

2010 ◽  
Author(s):  
Robert Lam ◽  
Xueqing Zhang ◽  
Mark Chen ◽  
Dean Ho
Keyword(s):  
Carbon Nanotubes ◽  
Drug Delivery ◽  
Surface Modification ◽  
Aspect Ratio ◽  
Biomedical Applications ◽  
Internalization Mechanism ◽  
Mechanism And Kinetics ◽  
Energy Dependent ◽  
The Relationship ◽  
Kinetics Of

Several reports have described the relationship between size, aspect ratio, surface modification and internalization for a variety of nanoparticles (i.e. gold, polymer, carbon nanotubes). Nanodiamonds (NDs) in particular have recently been implicated in a variety of biomedical applications. One of the most promising is in utilizing NDs as drug delivery carriers where successful internalization is of utmost importance. A few reports recently have demonstrated the energy dependent internalization of bare NDs. In this report, we investigate the internalization mechanism and kinetics of functional ND-conjugate translocation.

Preparation of MgB2 powder for ex situ tape with high Jc-B performance

2008 ◽  
Vol 23 (2) ◽  
pp. 486-493 ◽  
Author(s):  
Takayuki Nakane ◽  
Hiroaki Kumakura
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Critical Current Density ◽  
Heating Time ◽  
The Other ◽  
Ex Situ ◽  
Preparation Process ◽  
Powder Preparation ◽  
Preparation Conditions ◽  
The Relationship

The relationship between the preparation conditions of MgB2 powder and the performance of the critical current density (Jc) of an applied magnetic field (B) of the final ex situ tape produced from it was investigated. The pelletizing pressure of the precursor is crucially important for improving the Jc-B performance of ex situ tape. The higher the pressure, the greater the resulting Jc of the ex situ MgB2 tape. We have shown that the pelletizing pressure used for the precursor mixture during the powder preparation process affects the phases formed in the MgB2. On the other hand, the heating time used is effective in changing the slope of the Jc-B curve of the final tape. This is thought to be due to a change in the crystallinity of the prepared MgB2 powder. The experimental data gathered here will become the basis for investigating the establishment of a guideline for preparing the starting powder used for the manufacture of ex situ MgB2 tape.

On Refining the Relationship between Aspect Ratio and Percolation Threshold of Practical Carbon Nanotubes/Polymer Nanocomposites

2011 ◽  
Vol 50 (8R) ◽  
pp. 080214 ◽  
Author(s):  
Zhi-Min Dang ◽  
Khurram Shehzad ◽  
Jun-Wei Zha ◽  
Tajamal Hussain ◽  
Nie Jun ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Percolation Threshold ◽  
Polymer Nanocomposites ◽  
The Relationship

Particle Aspect-Ratio and Agglomeration-State Effects on the Effective Thermal Conductivity of Aqueous Suspensions of Multiwalled Carbon Nanotubes

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Anna S. Cherkasova ◽  
Jerry W. Shan
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Effective Thermal Conductivity ◽  
Particle Aggregation ◽  
Multiwalled Carbon ◽  
Agglomeration State ◽  
Particle Aspect Ratio ◽  
Absorption Measurements ◽  
Thermal Conductivities

The effective thermal conductivities of aqueous nanofluids containing surfactant-stabilized multiwalled carbon nanotubes were measured and compared with the predictions of effective medium theory (Nan, C.-W., et al., 1997, “Effective Thermal Conductivity of Particulate Composites With Interfacial Thermal Resistance,” J. Appl. Phys., 81(10), pp. 6692–6699). Detailed characterization of nanotube morphology was carried out through electron microscopy, while the nanotube agglomeration state was monitored through optical microscopy and absorption measurements. An optimum surfactant-to-nanotube mass ratio was found for the particular surfactant, sodium dodecylbenzene sulfonate, which resulted in the greatest increase in thermal conductivity. Taking into consideration the volume-weighted aspect ratio of the nanotubes, the measured thermal conductivities of the suspensions were shown to be in good agreement with calculations for a reasonable choice of interfacial resistance on the particle/liquid interface. The effect of particle aspect ratio on the suspension’s thermal conductivity was further demonstrated and compared with theory by reducing the nanotube length through intense ultrasonication. The effect of particle aggregation on the thermal conductivity was also investigated by destabilizing previously stable suspensions with ethanol addition, which causes surfactant desorption and bundling of nanotubes. The measured thermal conductivities were correlated with absorption measurements and microscopic visualizations to show that particle aggregation decreases the thermal conductivity of the nanofluid by reducing the effective particle aspect ratio.

scholarly journals Experimental study of the behaviour of mini-charge underwater explosion bubbles near different boundaries

2010 ◽  
Vol 651 ◽  
pp. 55-80 ◽  
Author(s):  
C. F. HUNG ◽  
J. J. HWANGFU
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Underwater Explosion ◽  
The Other ◽  
Predictive Index ◽  
Local Vibration ◽  
Cavitation Bubbles ◽  
Relative Value ◽  
Similarities And Differences ◽  
The Relationship

This work experimentally studies the behaviour of underwater explosion bubbles near different boundaries. The results are compared with theoretical and experimental data on cavitation bubbles. Although explosion and cavitation bubbles behave similarly on a macroscopic level, there are still some differences, most of which are from the explosive nature of the explosion bubble. The relationship between bubble migration and the Kelvin impulse, surface inertia m* and surface stiffness k* is investigated. We found that none of them comprehensively predicts the migration of both cavitation and explosion bubbles when boundary elasticity is considered. This elasticity should be considered as a relative value with respect to bubble size. On the other hand, the phase between local vibration of boundaries and the pulsation of bubbles could be a useful predictive index of bubble migration. When using research results developed for cavitation bubbles in relation to explosion bubbles, the material presented here may be useful for pointing out their similarities and differences.

3D Simulation Modeling for the Electrical Conductivity of Carbon Nanotube Networks in Polymer Nanocomposites

2021 ◽  
Vol 896 ◽  
pp. 39-44
Author(s):  
Yuan Zheng Luo ◽  
You Qi Wan ◽  
Wei Hong
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Aspect Ratio ◽  
Search Algorithm ◽  
Three Dimensional ◽  
Conductive Network ◽  
Dimethyl Siloxane ◽  
Potential Applications ◽  
The Relationship ◽  
Carbon Nanotube Networks

In this paper, we developed a three-dimensional percolation model to investigate the effects of the concentration and morphology of CNTs (carbon nanotubes) on the electrical conductivity of the nanocomposites. In the model, we judged the connections between CNTs by range search algorithm based on KD-Tree structure. At the same time, DIJKSTRA-Melissa algorithm was applied to efficiently find all the conductive paths instead of finding conductive network in traditional methods. From the simulation results, CNTs with higher aspect ratio were easier to form the conductive network. In a certain range of CNT’s concentration, the relationship between the conductivity of the conductive network and the carbon nanotubes was basically consistent with the classical percolation theory. To verify our simulation model, the morphological, electrical properties of Carbon nanotubes (CNTs)/poly(dimethyl siloxane) (PDMS) nanocomposites with different aspect ratio (AR) of MWNTs were systematically studied. In conclusion, these unique advantageous properties could be exploited to suggest potential applications of artificial electronic skin.

scholarly journals Chiral Stationary Phases and their Relationship with Enantiomer Structures in Enantioseparation Research of Analytical Laboratory

2017 ◽  
Vol 59 (1) ◽  
Author(s):  
Shun Yao
Keyword(s):  
Molecular Structure ◽  
Experimental Data ◽  
Mandelic Acid ◽  
Theoretical Study ◽  
Stationary Phases ◽  
Chiral Stationary Phases ◽  
The Other ◽  
Thermodynamic Mechanism ◽  
Mandelic Acid Derivatives ◽  
The Relationship

Chiral stationary phases (CSPs) and molecular structure of enantiomers are two independent but related aspects in enantioseparation, which are discussed on the basis of the experimental data from the previous study. Two enantioseparation experiments are performed to illustrate the relationship between enantiomer structures and chiral stationary phases, one is the resolution of mandelic acid derivatives and the other is about prasugrel. Thermodynamic mechanism and theoretical study with computational chemistry method is helpful to understand the interactions of enantiomer and CSPs.

On Refining the Relationship between Aspect Ratio and Percolation Threshold of Practical Carbon Nanotubes/Polymer Nanocomposites

2011 ◽  
Vol 50 (8) ◽  
pp. 080214 ◽  
Author(s):  
Zhi-Min Dang ◽  
Khurram Shehzad ◽  
Jun-Wei Zha ◽  
Tajamal Hussain ◽  
Nie Jun ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Percolation Threshold ◽  
Polymer Nanocomposites ◽  
The Relationship

Method for Finding Mass-Absorption Coefficients by Empirical Equations and Graphs

1961 ◽  
Vol 5 ◽  
pp. 153-160 ◽  
Author(s):  
J. Leroux
Keyword(s):  
Experimental Data ◽  
Empirical Equation ◽  
The Other ◽  
Empirical Equations ◽  
Absorption Coefficients ◽  
Modern Equipment ◽  
Mass Absorption ◽  
Complete Set ◽  
Logical Order ◽  
The Relationship

AbstractA brief description of the theoretical approach of this new method is given. The main purpose of the method is to correlate in a more logical order not only the data yielding the two laws relating mass-absorption coefficient to wavelength and to atomic number, respectively, but also to delineate, within two discontinuities, the relationship existing between each value and the other ones taken as a whole. The empirical equation relating μ to λ is μ = Cλn. A table of complete values for the constant C and die power n to be assigned in the equation is given for finding the values of mass-absorption coefficients above unity for all elements (except hydrogen) and for all wavelengths between 0.17837 and 10 A. It is believed that until a complete set of experimental data obtained with modern equipment is available, this proposed method fills the enormous gaps between actual compiled values.

MODELING FOR HYDRAULIC PERMEABILITY AND KOZENY–CARMAN CONSTANT OF POROUS NANOFIBERS USING A FRACTAL APPROACH

Fractals ◽  
2015 ◽  
Vol 23 (03) ◽  
pp. 1550029 ◽  
Author(s):  
BOQI XIAO ◽  
XING TU ◽  
WEN REN ◽  
ZONGCHI WANG
Keyword(s):  
Experimental Data ◽  
Present Model ◽  
Fractal Theory ◽  
Fractal Dimensions ◽  
Hydraulic Permeability ◽  
Fractal Approach ◽  
Microstructural Parameters ◽  
Fractal Models ◽  
Model Predictions ◽  
Analytical Expressions

In this study, the analytical expressions for the hydraulic permeability and Kozeny–Carman (KC) constant of porous nanofibers are derived based on fractal theory. In the present approach, the permeability is explicitly related to the porosity and the area fractal dimensions of porous nanofibers. The proposed fractal models for KC constant is also found to be a function of the microstructural parameters (porosity, area fractal dimensions). Besides, the present model clearly indicates that KC constant is not a constant and increases with porosity. However, KC constant is close to a constant value which is 18 for ϕ > 0.8. Every parameter of the proposed formulas of calculating permeability and KC constant has clear physical meaning. The model predictions are compared with the existing experimental data, and fair agreement between the model predictions and experimental data is found for different porosities.

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