Related Experiment Video

Updated: Jan 26, 2026

Assessment of Stress Effects on Cognitive Flexibility using an Operant Strategy Shifting Paradigm
07:26

Assessment of Stress Effects on Cognitive Flexibility using an Operant Strategy Shifting Paradigm

Published on: May 4, 2020

3.9K

Inflammation and Endotyping in Chronic Rhinosinusitis-A Paradigm Shift

Sinead Ahern1, Anders Cervin2,3

  • 1The University of Queensland, UQ Centre for Clinical Research, Herston, Queensland 4029, Australia. sinead.ahern@uq.net.au.

Medicina (Kaunas, Lithuania)
|April 10, 2019
PubMed

Keywords:
CRSchronic rhinosinusitisendotypinginflammation

More Related Videos

In vivo Imaging Method to Distinguish Acute and Chronic Inflammation07:10

In vivo Imaging Method to Distinguish Acute and Chronic Inflammation

Published on: August 16, 2013

20.7K
Chronic Stress Shifts Effort-Related Choice Behavior in a Y-Maze Barrier Task in Mice09:37

Chronic Stress Shifts Effort-Related Choice Behavior in a Y-Maze Barrier Task in Mice

Published on: August 13, 2020

12.1K

Related Concept Videos

Inflammation01:38

Inflammation

Overview
61.9K
NMR Spectroscopy: Chemical Shift Overview01:15

NMR Spectroscopy: Chemical Shift Overview

The position of the absorption signal of a sample is reported relative to the position of the signal of tetramethylsilane (TMS), which is added as an internal reference while recording spectra. The difference between the absorption frequencies of the sample and TMS (in Hz) is divided by the spectrometer operating frequency (in MHz) to obtain a dimensionless quantity called the chemical shift. It is reported on the δ (delta) scale and expressed in parts per million.
For instance, the proton...
3.1K
Proton (¹H) NMR: Chemical Shift01:07

Proton (¹H) NMR: Chemical Shift

Organic molecules primarily contain carbon and hydrogen atoms. While all the hydrogen isotopes are NMR-active, protium or hydrogen-1 is the most abundant. It has a significant energy separation between its nuclear spin states due to its large gyromagnetic ratio. As per Boltzmann's distribution, an increase in the energy separation implies a greater excess population of nuclei available for excitation, resulting in a strong NMR absorption signal.
Absorption signals of all the protium nuclei...
3.3K
Chemical Shift: Internal References and Solvent Effects01:17

Chemical Shift: Internal References and Solvent Effects

In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added, and the frequency difference between the reference signal and sample signals is measured.
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
1.3K
π Electron Effects on Chemical Shift: Overview01:27

π Electron Effects on Chemical Shift: Overview

An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.6K
Inductive Effects on Chemical Shift: Overview01:27

Inductive Effects on Chemical Shift: Overview

The protons in unsubstituted alkanes are strongly shielded with chemical shifts below 1.8 ppm. Methine, methylene, and methyl protons appear at approximately 1.7, 1.2 and 0.7 ppm, while the proton signal from methane appears at 0.23 ppm. An electronegative substituent, such as chlorine, withdraws the electron density from the protons, increasing their chemical shift. Progressive substitution of the hydrogens in methane by chlorine shifts the proton signals increasingly downfield, to 3.05 ppm in...
2.1K