Effect of a quenched random field on a continuous symmetry breaking transition: Nematic to smectic-<i>A</i>transition in octyloxycyanobiphenyl-aerosil dispersions
Bibliographic record
Abstract
High-resolution x-ray diffraction and ac-calorimetric experiments have been carried out on the liquid-crystal octyloxycyanobiphenyl in which aerosil particles are dispersed. The measurements were made over a temperature range around the bulk nematic to smectic-A transition temperature. At this transition the liquid crystal breaks translational symmetry in a single direction. The silica particles, which hydrogen bond together to form a very low density gel, provide the quenched disorder. The random gel leads to observable broadening of the x-ray reflection from the smectic layers. The structure factor is well described by modeling the effect of the aerosils as a quenched random field. Dispersed aerosils are thought to pin both the direction of the translational ordering and the position of the layers. The latter appears to have the greatest effect on the x-ray line shape. We show that the aerosil surface area, as verified by small-angle scattering, equates to the variance of the random field. Calorimetric results reveal substantial change in the specific heat peak associated with the nematic to smectic-A transition. As the concentration of aerosil increases, the specific heat peak remains sharp yet decreases in magnitude and shifts in temperature in a nonmonotonic fashion. In this regime, the critical exponent alpha becomes progressively smaller. For the samples with the largest concentrations of aerosil particles the C(p)(N-A) peak becomes highly smeared and shifts smoothly to lower temperatures.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".