Instructional Aids to Accompany University Physics

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

doi:10.1016/b978-0-12-059858-8.50005-4

Cited by 4 publications

(3 citation statements)

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“…This trend is as expected according to previous work 14 and can be attributed to both the differences in the viscosity 23 and Stokes' law which predicts that smaller particles have lower sedimentation terminal velocities. 10,24 iv. Gas Uptake.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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: ■ Results and Discussionmentioning

confidence: 99%

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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“…Heat absorbed during a phase change is used to modify the microscopic structure of the substance. Heat absorbed by a solid during melting is used to break the bonds between atoms and a tiny fraction of heat absorbed is converted into work (PdVwhere P is the pressure and dV is the change in volume) which is associated with volume change [9]. Thus the potential of latent heat is highly linked with the number of breakage in chemical bonds.…”

Section: Introductionmentioning

confidence: 99%

Nano additive enhanced salt hydrate phase change materials for thermal energy storage

Kalidasan

Pandey

Saidur

et al. 2022

International Materials Reviews

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Energy storage plays a vital role in sustainable development. Focus on energy storage using phase change materials (PCMs) are of current research hotspot due to high latent heat value. Nevertheless, poor thermal conductivity, supercooling, phase separation, corrosive nature of salt hydrate is of great concern. Distress related to properties of PCM is resolved using nano additives. Major research focus on the dispersion of nano additive with PCM depends on (a) technique of preparing a novel composite PCM; (b) improvement of their thermophysical characteristic; and (c) advanced application for human comfort without polluting the environment. This article presents a critical review of hybridization techniques of metal, carbon and polymer additives on salt hydrate PCMs. To facilitate researchers, the significant variation on thermophysical properties of salt hydrate with nano additives are vitally compared, analysed and critically reviewed. This review article also includes the advanced application of nano additivesbased salt hydrate PCMs.

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Instructional Aids to Accompany University Physics

Cited by 4 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

Nano additive enhanced salt hydrate phase change materials for thermal energy storage

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