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Related Concept Videos

Angle of Twist: Problem Solving01:13

Angle of Twist: Problem Solving

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An electric motor applies a torque of 700 N·m to an aluminum shaft, triggering a stable rotation. Two pulleys, B and C, are subjected to torques of 300 N·m and 400 N·m, respectively. The modulus of rigidity is provided as 25 GPa. With the knowledge of the length and diameter of each segment, the twist angle between the two pulleys can be computed. First, a section cut is made between pulleys B and C, and the cut cross-section is analyzed using a free-body diagram. Given that the...
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Angle of Twist - Elastic Range01:13

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Consider a cylindrical shaft with a length denoted by L and a consistent cross-sectional radius referred to as r. This shaft undergoes a torque at the free end. The highest shearing strain within the shaft is directly proportional to the twist angle and the radial distance from the shaft axis. When the shaft behaves elastically, this shearing strain can be articulated using variables such as the applied torque, radial distance, the polar moment of inertia, and the modulus of rigidity. By...
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Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)01:20

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Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
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Residual Stresses in Circular Shafts01:10

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In materials that exhibit elastic and plastic behavior, known as elastoplastic materials, residual stresses can accumulate when these materials experience plastic deformation. This deformation arises from either high levels of shearing stress or significant strains. Residual stresses are internal stresses that persist within a material after removing the external force causing deformation. This phenomenon is demonstrated when observing the behavior of a shaft under torque; notably, the...
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Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)01:22

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Spin–Spin Coupling: One-Bond Coupling01:17

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Related Experiment Video

Updated: Oct 19, 2025

Magnetic Tweezers for the Measurement of Twist and Torque
11:41

Magnetic Tweezers for the Measurement of Twist and Torque

Published on: May 19, 2014

23.5K

Double Twist.

Wei-Chieh Lee1,2, Yung-Lung Chen2

  • 1Institute of Clinical Medicine, College of Medicine, National Cheng Kung University.

International Heart Journal
|September 21, 2021
PubMed
Summary
This summary is machine-generated.

A rare Twiddler syndrome complication occurred in a patient with an implantable cardioverter defibrillator (ICD). The ICD lead twisted, causing malfunction and requiring a new lead implantation.

Keywords:
ComplicationIntracardiac defibrillatorLead extraction

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Area of Science:

  • Cardiology
  • Medical Devices

Background:

  • A 78-year-old woman with a history of ventricular arrhythmia received a single-chamber implantable cardioverter defibrillator (ICD) for secondary prevention.
  • The patient's ICD lead experienced a sudden decrease in sense amplitude, which did not recover.

Observation:

  • The patient engaged in prolonged, repetitive arm movements while playing mahjong overnight.
  • Intracardiac electrograms revealed ventricular lead noise preceding the amplitude decrease.

Findings:

  • Chest radiography demonstrated significant lead twisting within the ICD pocket and retraction into the right atrium.
  • The existing ICD lead was unable to be straightened or removed due to its condition.

Implications:

  • A new ICD lead was successfully implanted in the right ventricle.
  • The patient was placed on anti-coagulation therapy to mitigate thrombosis risk associated with the retained old ICD lead.
  • This case highlights the potential for mechanical complications like Twiddler syndrome, even with seemingly benign patient activities.