NMR Self-Diffusion of Molecular and Macromolecular Species in Dextran Solutions and Gels
Bibliographic record
Abstract
To provide insights into the diffusion properties of micelles in hydrogels and, in general, of solutes in dextran gels, self-diffusion coefficients of small organic solutes and large micelles were measured in dextran solutions and gels, using pulsed-field gradient NMR. The self-diffusion of the solutes was shown to be slower in dextran solutions than in D 2 O and even slower in dextran gels. The extent of the diffusion reduction was more pronounced for higher dextran concentrations. For a series of molecules with a molecular weight between 46 and 78, the self-diffusion coefficient in dextran gels (20% w/w) corresponded, on average, to about 0.39 of the values measured in bulk water. This hindered diffusion was mainly associated with the obstacles created by the polysaccharide segments. There was no evidence in the diffusion measurements of interaction between dextran and solutes capable of hydrogen bonding. The reduction of diffusion in dextran solutions and gels was very drastic in the case of micelles. For Triton X-100, the self-diffusion coefficient in dextran gel was about 7% of that observed in water. The values were, in fact, on the same order of the dextran chain diffusion coefficient. This finding suggests that these large macroassemblies can hardly move in dextran gels.
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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".