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Magnetic field induced alignment of the directors of a smectic-A liquid crystal.

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics · 1999 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 4025

Deuterium NMR monitoring indicated that magnetic-field-induced alignment of directors in a smectic-A sample is qualitatively different from that in nematic samples. Results for the pure mesogen (deuterated at the alpha chain position) were compared with align…

Study snapshot

PublicationPhysical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics · 1999
Study typeother
Reported directionUnclear
Evidence ratingInsufficient

Abstract

Deuterium NMR is used to monitor the magnetic field induced alignment of the directors in the smectic A phase of 4-octyl-4(')-cyanobiphenyl. The experiments consist of first preparing the sample as a monodomain by cooling slowly from the nematic phase in the magnetic field of the NMR spectrometer. The tube containing the sample is then rotated quickly through an angle theta(+), and the subsequent field induced alignment process followed by recording deuterium spectra over a period of time. The results obtained show that the magnetic field induced alignment of the directors in a smectic-A sample is qualitatively different from that of nematic samples. Results are reported for the pure mesogen containing deuteriums at the alpha chain position, and these are compared with data obtained on the alignment process by monitoring the deuterium spectrum of a small amount of an added solute, p-xylene-d(10).

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeother
Effect directionunclear
PopulationNot supplied
Sample sizeNot supplied
Exposurespectra recorded over a period of time following sample rotation
Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

Deuterium NMR monitoring indicated that magnetic-field-induced alignment of directors in a smectic-A sample is qualitatively different from that in nematic samples. Results for the pure mesogen (deuterated at the alpha chain position) were compared with alignment data obtained using deuterium spectra of a small amount of added p-xylene-d(10) solute.

Outcomes measured

  • magnetic-field-induced alignment of directors in smectic-A liquid crystal
  • deuterium NMR spectra changes over time during alignment process
  • comparison of alignment behavior between smectic-A and nematic samples

Limitations

  • No magnetic field strength or NMR operating frequency reported in the abstract.
  • No quantitative results or effect sizes described in the abstract.
  • Not a health/biological effects study; focuses on liquid-crystal director alignment behavior.
View raw extracted JSON
{
  "study_type": "other",
  "exposure": {
    "band": null,
    "source": "magnetic field of the NMR spectrometer",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "spectra recorded over a period of time following sample rotation"
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "magnetic-field-induced alignment of directors in smectic-A liquid crystal",
    "deuterium NMR spectra changes over time during alignment process",
    "comparison of alignment behavior between smectic-A and nematic samples"
  ],
  "main_findings": "Deuterium NMR monitoring indicated that magnetic-field-induced alignment of directors in a smectic-A sample is qualitatively different from that in nematic samples. Results for the pure mesogen (deuterated at the alpha chain position) were compared with alignment data obtained using deuterium spectra of a small amount of added p-xylene-d(10) solute.",
  "effect_direction": "unclear",
  "limitations": [
    "No magnetic field strength or NMR operating frequency reported in the abstract.",
    "No quantitative results or effect sizes described in the abstract.",
    "Not a health/biological effects study; focuses on liquid-crystal director alignment behavior."
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "deuterium NMR",
    "magnetic field",
    "director alignment",
    "smectic-A",
    "nematic",
    "4-octyl-4'-cyanobiphenyl",
    "p-xylene-d10"
  ],
  "suggested_hubs": []
}
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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1103/physreve.60.1831
PubMed: 11969970

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