Threshold-dependent nonlinear scattering from porphyrin nanobubbles for vascular and extravascular applications
Bibliographic record
Abstract
Abstract Nanobubbles hold potential for expanding utility of ultrasound contrast-based applications to extravascular targets, but their acoustic response and the effects of the surrounding environment remain relatively unexplored. Here we investigate the dynamics of porphyrin-encapsulated nanobubbles (diameter <0.4 µ m; 10 6 ml −1 ) at clinically relevant frequencies (2.5 MHz and 8 MHz) as a function of pressure (0.1–1.0 MPa) in vessel- and tissue-mimicking phantoms to gain an understanding of nanobubble behaviour in intra- and extravascular compartments. The results provide the first direct observation that nanobubbles can initiate nonlinear scattering, and that they do so in a pressure-dependent manner. It is further demonstrated that while nanobubbles in confining media require higher pressures for nonlinearities and demonstrate reduced scattering, they can exhibit sustained and non-destructive cavitation. Bubble models are then used to gain mechanistic insights into experimentally observed nanobubble dynamics and confirm sensitivity to nonlinear shell rheology, particularly to radially-dependent surface tension and the characteristic time constant for shear-thinning.
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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 | 0.000 |
| 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".