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Related Concept Videos

Thermal Sigmatropic Reactions: Overview01:16

Thermal Sigmatropic Reactions: Overview

Sigmatropic rearrangements are a class of pericyclic reactions in which a σ bond migrates from one part of a π system to another. These are intramolecular rearrangements where the total number of σ and π bonds remain unchanged.
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred to as...
Bewley Lattice Diagram01:12

Bewley Lattice Diagram

The Bewley lattice diagram, developed by L. V. Bewley, effectively organizes the reflections occurring during transmission-line transients. It visually represents how voltage waves propagate and reflect within a transmission line, making it easier to understand the complex interactions that occur.
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[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement

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Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule01:10

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¹H NMR: Complex Splitting01:13

¹H NMR: Complex Splitting

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Debye–Huckel–Onsager Conductance Equation01:28

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Related Experiment Video

Updated: Jun 13, 2026

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations
13:56

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Published on: October 12, 2019

B1 mapping by Bloch-Siegert shift.

Laura I Sacolick1, Florian Wiesinger, Ileana Hancu

  • 1Imaging Technologies Lab, GE Global Research, Munich, Germany. laura.sacolick@ge.com

Magnetic Resonance in Medicine
|May 1, 2010
PubMed
Summary
This summary is machine-generated.

A new Bloch-Siegert shift method offers faster and more accurate radiofrequency field (B1+) mapping. This technique encodes B1+ information into signal phase, improving speed and robustness for clinical applications.

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Mechanical Mapping of Spheroids Using Brillouin Spectroscopy
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Mechanical Mapping of Spheroids Using Brillouin Spectroscopy

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Last Updated: Jun 13, 2026

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations
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Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Published on: October 12, 2019

Mechanical Mapping of Spheroids Using Brillouin Spectroscopy
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Published on: December 12, 2025

Area of Science:

  • Magnetic Resonance Imaging
  • Radiofrequency Physics

Background:

  • Conventional B1+ mapping methods like double-angle are time-consuming and sensitive to field inhomogeneities.
  • Accurate radiofrequency field mapping is crucial for quantitative MRI.

Purpose of the Study:

  • To present a novel, rapid, and robust method for B1+ mapping using the Bloch-Siegert shift.
  • To demonstrate the quantitative accuracy and speed advantages of this new technique.

Main Methods:

  • Utilizes the Bloch-Siegert frequency shift, which is proportional to B1 squared.
  • Encodes B1+ information into signal phase, not magnitude.
  • Employs a phase difference of two acquisitions with symmetrically applied off-resonance RF pulses to negate artifacts.

Main Results:

  • Achieves B1+ mapping in vivo with a slice acquisition time of 25 seconds.
  • Demonstrates quantitative comparability to a 21-minute double-angle B1+ map.
  • The method is robust against static field inhomogeneity and chemical shift.

Conclusions:

  • The Bloch-Siegert shift method provides a significant advancement in B1+ mapping speed and accuracy.
  • Enables high-resolution B1+ mapping within a clinically acceptable timeframe.
  • Offers a robust alternative to conventional B1+ mapping techniques.