News tagged with nuclear magnetic resonance

Related topics: journal of the american chemical society , protein

Imaging the brain's energy usage

A team of researchers led by Kai-Hsiang Chuang of the A*STAR Singapore Bioimaging Consortium has developed a new imaging technique to measure the rate at which the brain consumes glucose, without using radioactively ...

Jan 22, 2014
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Researchers tease apart workings of a common gene

Researchers at Weill Cornell Medical College have discovered why a tiny alteration in a brain gene, found in 20 percent of the population, contributes to the risk for anxiety, depression and memory loss.

Sep 19, 2013
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What scientists can see in your pee

Researchers at the University of Alberta announced today that they have determined the chemical composition of human urine. The study, which took more than seven years and involved a team of nearly 20 researchers, has revealed ...

Sep 05, 2013
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Anchoring ABL for a better fate

Chronic Myelogenous Leukemia (CML) is a cancer of the white blood cells that is most commonly found in adults and in the elderly. Its incidence has been estimated to be 1 to 2 in 100,000 people. CML was the first cancer to ...

Aug 27, 2013
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Patients benefit from primary care wellness program

(HealthDay)—Patients benefit from the Americans In Motion-Healthy Interventions (AIM-HI) approach to promoting physical activity, healthy eating, and emotional well-being regardless of whether or not family ...

Jul 12, 2013
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Novel screening tests for liver cancer

New data from two clinical trials presented today at the International Liver Congress 2013 demonstrate substantial improvements in the detection of both hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC) using diagnostic ...

Apr 26, 2013
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New details on the molecular machinery of cancer

Researchers with Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have provided important new details into the activation of the epidermal growth factor ...

Feb 11, 2013
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Nuclear magnetic resonance

Nuclear magnetic resonance (NMR) is a property that magnetic nuclei have in a magnetic field and applied electromagnetic (EM) pulse, which cause the nuclei to absorb energy from the EM pulse and radiate this energy back out. The energy radiated back out is at a specific resonance frequency which depends on the strength of the magnetic field and other factors. This allows the observation of specific quantum mechanical magnetic properties of an atomic nucleus. Many scientific techniques exploit NMR phenomena to study molecular physics, crystals and non-crystalline materials through NMR spectroscopy. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI).

All nuclei that contain odd numbers of nucleons have an intrinsic magnetic moment and angular momentum, in other words a spin > 0. The most commonly studied nuclei are 1H (the most NMR-sensitive isotope after the radioactive 3H) and 13C, although nuclei from isotopes of many other elements (e.g. 2H, 10B, 11B, 14N, 15N, 17O, 19F, 23Na, 29Si, 31P, 35Cl, 113Cd, 195Pt) are studied by high-field NMR spectroscopy as well.

A key feature of NMR is that the resonance frequency of a particular substance is directly proportional to the strength of the applied magnetic field. It is this feature that is exploited in imaging techniques; if a sample is placed in a non-uniform magnetic field then the resonance frequencies of the sample's nuclei depend on where in the field they are located. Since the resolution of the imaging techniques depends on how big the gradient of the field is, many efforts are made to develop more powerful magnets, often using superconductors. The effectiveness of NMR can also be improved using hyperpolarization, and/or using two-dimensional, three-dimensional and higher dimension multi-frequency techniques.

The principle of NMR usually involves two sequential steps:

The two fields are usually chosen to be perpendicular to each other as this maximises the NMR signal strength. The resulting response by the total magnetization (M) of the nuclear spins is the phenomenon that is exploited in NMR spectroscopy and magnetic resonance imaging. Both use intense applied magnetic fields (H0) in order to achieve dispersion and very high stability to deliver spectral resolution, the details of which are described by chemical shifts, the Zeeman effect, and Knight shifts (in metals).

NMR phenomena are also utilized in low-field NMR, NMR spectroscopy and MRI in the Earth's magnetic field (referred to as Earth's field NMR), and in several types of magnetometers.

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