Preface

Arfken, George B.; Griffing, David F.; Kelly, Donald C.; Priest, Joseph

doi:10.1016/b978-0-12-059858-8.50004-2

Cited by 5 publications

(6 citation statements)

References 0 publications

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“…The instability index, calculated by dividing the degree of clarification at a given centrifugation time by the maximum clarification, increased with increasing particle size. This trend is as expected according to previous work and can be attributed to both the differences in the viscosity and Stokes’ law which predicts that smaller particles have lower sedimentation terminal velocities. , …”

Section: Resultssupporting

confidence: 91%

Effects of Particle Size on the Gas Uptake Kinetics and Physical Properties of Type III Porous Liquids

Liu,

Lai,

James

2024

ACS Appl. Mater. Interfaces

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Type III porous liquids (PLs) consist of porous solid particles dispersed in a size-excluded liquid phase and are attracting much attention as novel media for applications such as gas separation. However, the effects of fundamental variables such as particle size on their physical properties are currently largely unknown. Here we study the effects of particle size in a series of porous liquids based on solid Al(OH)(fumarate) (a microporous metal−organic framework, MOF) with particle sizes of 60 nm, 200−600 nm, or 800−1000 dispersed in liquid polydimethylsiloxane (PDMS). Properties examined include physical stability of the dispersion, viscosity, total CO 2 uptake, and kinetics of CO 2 uptake. As expected, both physical stability and viscosity decreased with increasing particle size. Unexpectedly, total gravimetric gas uptake also varied with particle size, being greatest for the largest particles, which we ascribe to larger particles having a lower relative content of surface-bound FMA ligands. Various models for the gas uptake kinetic data were considered, specifically adsorption reaction models such as pseudo-first-order, pseudo-second-order, and Elovich models. In contrast to pure PDMS, which showed first-order kinetics, all PLs fit best to the Elovich model confirming that their uptake mechanism is more complex than for a simple liquid. Adsorption diffusion models, specifically Weber and Morris' intraparticle model and Boyd's model, were also applied which revealed a three-step process in which a combination of diffusion through a surface layer and intraparticle diffusion were ratelimiting. The rate of gas uptake follows the order PDMS < PL1 < PL2 < PL3, showing that the porous liquids take up gas more rapidly than does PDMS and that this rate increases with particle size. Overall, the study suggests that for high gas uptake and fast uptake kinetics, large particles may be preferred. Also, the fact that large particles resulted in low viscosity may be advantageous in reducing the pumping energy needed in flow separation systems. Therefore, the work suggests that finding ways to stabilize PLs with large particles against phase separation could be advantageous for optimizing the properties of PLs toward applications.

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Section: Resultssupporting

confidence: 91%

Effects of Particle Size on the Gas Uptake Kinetics and Physical Properties of Type III Porous Liquids

Liu,

Lai,

James

2024

ACS Appl. Mater. Interfaces

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“…However, according to Fourier’s law, a difference is unlikely to significantly affect the results of the modeling, as the temperature gradient across the skull layer is most likely to be driven by its thermal conductivity. 43 Density and specific heat capacity affect transient temperature dynamics rather than steady-state temperature distribution. The impact of cerebrospinal fluid flow was not taken into account in the modeling as it was assumed that cerebrospinal fluid did not contribute to metabolic heat given that it is replaced every 7.5 hours, 44 and the cerebrospinal fluid volume (150 mL) comprises a small percentage of the overall experiment volume.…”

Section: Discussionmentioning

confidence: 99%

Penumbral cooling in ischemic stroke with intraarterial, intravenous or active conductive head cooling: A thermal modeling study

Diprose,

Rao,

Ghate

et al. 2023

J Cereb Blood Flow Metab

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In ischemic stroke, selectively cooling the ischemic penumbra might lead to neuroprotection while avoiding systemic complications. Because penumbral tissue has reduced cerebral blood flow and in vivo brain temperature measurement remains challenging, the effect of different methods of therapeutic hypothermia on penumbral temperature are unknown. We used the COMSOL Multiphysics® software to model a range of cases of therapeutic hypothermia in ischemic stroke. Four ischemic stroke models were developed with ischemic core and/or penumbra volumes between 33–300 mL. Four experiments were performed on each model, including no cooling, and intraarterial, intravenous, and active conductive head cooling. The steady-state temperature of the non-ischemic brain, ischemic penumbra, and ischemic core without cooling was 37.3 °C, 37.5–37.8 °C, and 38.9–39.4 °C respectively. Intraarterial, intravenous and active conductive head cooling reduced non-ischemic brain temperature by 4.3 °C, 2.1 °C, and 0.7–0.8 °C respectively. Intraarterial, intravenous and head cooling reduced the temperature of the ischemic penumbra by 3.9–4.3 °C, 1.9–2.1 °C, and 1.2–3.4 °C respectively. Active conductive head cooling was the only method to selectively reduce penumbral temperature. Clinical studies that measure brain temperature in ischemic stroke patients undergoing therapeutic hypothermia are required to validate these hypothesis-generating findings.

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“…The non-equilibrium MD approach is used to calculate the thermal conductivity in this work. The thermal conductivity κ is obtained by Fourier's law, 35 where the heat flux density J is the amount of energy that flows through the unit area per unit time and is the temperature gradient along the thermal transport direction. Here, the cross-sectional area that the heat flows through is defined as , where d c and b are the tube diameter and the van der Waals thickness, respectively.…”

Section: Simulation Detailsmentioning

confidence: 99%

“…The non-equilibrium MD approach is used to calculate the thermal conductivity in this work. The thermal conductivity k is obtained by Fourier's law, 35 J ¼ Àk dT dx ;…”

Section: Simulation Detailsmentioning

confidence: 99%

Modulation of thermal conductivity of single-walled carbon nanotubes by fullerene encapsulation: the effect of vacancy defects

Jiang

2023

Phys. Chem. Chem. Phys.

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Preface

Cited by 5 publications

References 0 publications

Effects of Particle Size on the Gas Uptake Kinetics and Physical Properties of Type III Porous Liquids

Effects of Particle Size on the Gas Uptake Kinetics and Physical Properties of Type III Porous Liquids

Penumbral cooling in ischemic stroke with intraarterial, intravenous or active conductive head cooling: A thermal modeling study

Modulation of thermal conductivity of single-walled carbon nanotubes by fullerene encapsulation: the effect of vacancy defects

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