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Other Nuclides: 31P, 19F, 15N NMR01:16

Other Nuclides: 31P, 19F, 15N NMR

Many organic, inorganic, and biological molecules contain spin-half nuclei such as nitrogen-15, fluorine-19, and phosphorus-31. As a result, NMR studies of these nuclei have found extensive applications in chemical and biological research.
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Ideally, an unpaired electron shows a single peak in the EPR spectrum due to the transition between the two spin energy states. However, coupling interactions can occur between the spins of the unpaired electron and any neighboring spin-active nuclei. This hyperfine coupling results in hyperfine splitting, where the EPR signal is split into multiplets. The signals split into 2nI + 1 peaks, where n is the number of equivalent nuclei and I is the nuclear spin. These splitting patterns provide...
Atomic Nuclei: Magnetic Resonance01:05

Atomic Nuclei: Magnetic Resonance

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π Electron Effects on Chemical Shift: Overview01:27

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Diamagnetic Shielding of Nuclei: Local Diamagnetic Current01:14

Diamagnetic Shielding of Nuclei: Local Diamagnetic Current

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Updated: Jul 4, 2026

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo
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Published on: September 26, 2016

Electron paramagnetic resonance in human fingernails: the sponge model implication.

R A Reyes1, A Romanyukha, F Trompier

  • 1Uniformed Services University of the Health Sciences, Bethesda, MD, USA.

Radiation and Environmental Biophysics
|June 28, 2008
PubMed
Summary
This summary is machine-generated.

Electron paramagnetic resonance (EPR) fingernail dosimetry is improved by understanding non-radiation signals. Soaking fingernails in water effectively removes these interfering signals, enabling more accurate radiation dose measurements.

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Preparation of Fungal and Plant Materials for Structural Elucidation Using Dynamic Nuclear Polarization Solid-State NMR
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Area of Science:

  • Biophysics
  • Dosimetry
  • Materials Science

Background:

  • Electron paramagnetic resonance (EPR) fingernail dosimetry is hindered by non-radiation signals (mechanically induced signal [MIS] and background signal [BKS]) that overlap the radiation-induced signal (RIS).
  • These interfering signals make accurate dose measurements below 5 Gy extremely difficult.
  • Fingernail tissue's mechanical properties, including its sponge-like behavior and water absorption, are crucial for understanding these signals.

Purpose of the Study:

  • To investigate the nature of the mechanically induced signal (MIS) and background signal (BKS) in fingernail dosimetry.
  • To develop methods for isolating and distinguishing these non-radiation signals from the radiation-induced signal (RIS).
  • To establish a foundation for accurate in vivo EPR dosimetry using fingernails.

Main Methods:

  • Development and implementation of three distinct methods for isolating MIS and BKS.
  • Modeling fingernail tissue as a deformed sponge to understand mechanical stress absorption.
  • Investigating the effect of water soaking on signal components and measuring fingernail porosity.

Main Results:

  • Fingernail tissue deformation, analogous to a sponge, explains MIS and BKS as responses to elastic and plastic stresses.
  • Soaking fingernail samples in water for 10 minutes effectively eliminates the MIS without significantly altering the RIS.
  • Pre-soaked (unstressed) fingernails exhibit distinct dosimetric properties compared to stressed samples, including higher signal stability and less intense non-radiation components.

Conclusions:

  • The study proposes a new interpretation of mechanical deformation in fingernails, enabling differentiation between MIS and RIS.
  • Water soaking is identified as a practical method to remove interfering mechanical signals, paving the way for improved EPR dosimetry.
  • Findings support the potential for accurate in vivo EPR dosimetry using pre-soaked fingernails, overcoming limitations of previous methods.