Scaling of viscoelastic shell properties of lipid encapsulated microbubbles with frequency.
Bibliographic record
Abstract
While it has been established that nonlinear oscillations of lipid encapsulated microbubbles occur at frequencies of >10 MHz, the understanding of bubble behavior in this frequency range is limited and is not predicted by bubble models using shell properties derived at <5 MHz. Here we investigate the scaling of the viscoelastic shell properties of lipid encapsulated contrast agents with frequency and bubble size. Attenuation measurements were performed over 2–30 MHz and, using size distribution measurements and the linearized Rayleigh–Plesset equation, shell elasticity and viscosity terms were estimated. Experiments were performed on a series of narrow size distribution in-house agents with progressively smaller diameters, as well as the high frequency agent Micromarker. In-house agents peaked in attenuation at 4.2, 8.5, 13, and 22 MHz, and Micromarker rose until 21 MHz. The elasticity for in-house agents was comparable to other agents at lower frequencies, while the viscosity rapidly decreased above 10 MHz. For Micromarker, which has a different fabrication process, the elasticity was substantially higher than the in-house agent and over 15–30 MHz its viscosity was far lower viscosity than those reported at lower frequencies. The use of low shell viscosities in bubble models enables the prediction of nonlinear oscillations at higher frequencies.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".