The hot chocolate effect

Crawford, Frank S.

doi:10.1119/1.13080

Cited by 43 publications

(45 citation statements)

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“…Figure 7 shows fractional gas volume profiles calculated from the data shown in Figure 6 using eq 4. Crawford (2) and Woods (3) derived the relationship between the resonant frequency and the gas volume evolved during dissolution. The peak gas volume for the dissolution of 0.25 g of Cymbalta was roughly the same in water and in low concentrations of NaOH.…”

Section: Resultsmentioning

confidence: 99%

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pH Dependence of the Dissolution Rate of EntericCoated Drug Spheres Determined by Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS)

Evans-Hurson¹,

McSweeney²,

Vos³

et al. 2016

Dissolution Technol.

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Enteric coatings are widely used in formulations of drug delivery spheres. The coating protects an active pharmaceutical ingredient (API) from acidic conditions in the low pH environment of the stomach. The coating breaks down readily at higher pH in the lower intestine to allow absorption of the API. The thickness of the enteric coating is one of the factors that determine the release rate of the drug in the gastrointestinal tract. It is difficult to determine the loading of the drug layer and enteric coating on the core support sphere without conventional dissolution testing during and post manufacture. Broadband acoustic resonance dissolution spectroscopy (BARDS) potentially offers a new, rapid approach to characterizing enteric coatings during their manufacture. BARDS applications are based on reproducible changes in the compressibility of a solvent during dissolution, which is monitored acoustically via associated changes in the frequency of induced acoustic resonances. Two drug sphere formulations that yield characteristic and reproducible data were investigated. A steady-state acoustic lag time is associated with the disintegration of the enteric coating and drug layer in basic solution. This lag time is pH dependent and is indicative of the rate at which the coating and layers dissolve. BARDS analysis has the potential to characterize drug sphere formulations at-line in very short timescales. BARDS represents a complementary technique to conventional dissolution testing that could be used in precompliance testing for quality assurance during manufacture. BARDS data, in the future, may also be indicative of the likely performance of a formulation under USP dissolution testing. KEYWORDS:Hypromellose; enteric-coated spheres; dissolution; BARDS.

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Section: Resultsmentioning

confidence: 99%

“…The net effect is a significant reduction of the sound velocity in the liquid. The following relationship between the fractional bubble volume and the sound velocity in water was derived by Crawford (2) as given in eq 2:…”

Section: Introductionmentioning

confidence: 99%

pH Dependence of the Dissolution Rate of EntericCoated Drug Spheres Determined by Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS)

Evans-Hurson¹,

McSweeney²,

Vos³

et al. 2016

Dissolution Technol.

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show abstract

“…The more rigid a substance, the faster sound travels through it. Hence, the pitch of the sound goes up (Crawford 1982). This explanation appeals to a variable, 'aeration'.…”

mentioning

confidence: 98%

An Interventionist Approach to Causation in Psychology

Campbell¹

2007

Causal Learning

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My project in this paper is to extend the interventionist analysis of causation to give an account of causation in psychology. Many aspects of empirical investigation into psychological causation fit straightforwardly into the interventionist framework. I address three problems. First, the problem of explaining what it is for a causal relation to be properly psychological rather than merely biological. Second, the problem of rational causation: how it is that reasons can be causes. Finally, I look at the implications of an interventionist analysis for the idea that an inquiry into psychological causes must be an inquiry into causal mechanisms. I begin by setting out the main ideas of the interventionist approach.

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“…These bubble clouds are responsible for part of the ambient noise in the ocean below about 1000 Hz. 16 The physics of bubble acoustics has been the subject of previous "Apparatus and Demonstration Notes" within this journal, [17][18][19] but the apparatus described here complements and expands upon the previous work. The apparatus consists of a transparent PVC pipe about 0.5 m in length.…”

Section: Introductionmentioning

confidence: 65%

An audible demonstration of the speed of sound in bubbly liquids

Wilson

Roy

2008

American Journal of Physics

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The speed of sound in a bubbly liquid is strongly dependent upon the volume fraction of the gas phase, the bubble size distribution, and the frequency of the acoustic excitation. At sufficiently low frequencies, the speed of sound depends primarily on the gas volume fraction. This effect can be audibly demonstrated using a one-dimensional acoustic waveguide, in which the flow rate of air bubbles injected into a water-filled tube is varied by the user. The normal modes of the waveguide are excited by the sound of the bubbles being injected into the tube. As the flow rate is varied, the speed of sound varies as well, and hence, the resonance frequencies shift. This can be clearly heard through the use of an amplified hydrophone and the user can create aesthetically pleasing and even musical sounds. In addition, the apparatus can be used to verify a simple mathematical model known as Wood’s equation that relates the speed of sound of a bubbly liquid to its void fraction.

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The hot chocolate effect

Cited by 43 publications

References 0 publications

pH Dependence of the Dissolution Rate of EntericCoated Drug Spheres Determined by Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS)

pH Dependence of the Dissolution Rate of EntericCoated Drug Spheres Determined by Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS)

An Interventionist Approach to Causation in Psychology

An audible demonstration of the speed of sound in bubbly liquids

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