• solid-state NMR spectr
  • PhysOrg.com) -- A new study using solid-state NMR spectroscopy to analyze intact bone paves the way for atomic-level explorations of how disease and aging affect bone. (phys.org)
  • Today such sources are available as turn-key instruments, making DNP a valuable and indispensable method especially in the field of structure determination by high-resolution solid-state NMR spectroscopy DNP was first realized using the concept of the Overhauser effect, which is the perturbation of nuclear spin level populations observed in metals and free radicals when electron spin transitions are saturated by the microwave irradiation. (wikipedia.org)
  • transfer spectroscopy
  • His recent work has focused on developing new NMR methods (such as paramagnetic relaxation enhancement, dark state exchange saturation transfer spectroscopy and lifetime line broadening) to characterize the structure and dynamics of sparsely-populated states of macromolecules, which are important in macromolecular interactions but invisible to conventional structural and biophysical techniques. (wikipedia.org)
  • COSY
  • The first and most popular two-dimension NMR experiment is the homonuclear correlation spectroscopy (COSY) sequence, which is used to identify spins which are coupled to each other. (wikipedia.org)
  • typically
  • Also, for some metastatic lesions and for high-grade gliomas, typically, there are resonances corresponding to lactate or lipids ( 26 , 27 ). (aacrjournals.org)
  • These properties are fundamentally the same as those used in the more familiar magnetic resonance imaging (MRI), but the molecular applications use a somewhat different approach, appropriate to the change of scale from millimeters (of interest to radiologists) to nanometers (bonded atoms are typically a fraction of a nanometer apart), a factor of a million. (wikipedia.org)
  • Hyperpolarized noble gases are typically used in magnetic resonance imaging (MRI) of the lungs. (wikipedia.org)
  • experiment
  • We present a proof-of-principle experiment in which we search for PNC in the 13 C resonances of small molecules, and use the 1 H resonances, which are insensitive to PNC, as an internal reference. (osti.gov)
  • In the echo experiment, two short, intense pulses of radiofrequency magnetic field are applied to the spin ensemble at the nuclear resonance condition and are separated by a time interval of τ. (wikipedia.org)
  • In the Hahn-Maxwell experiment, the decay was modulated by two frequencies: one frequency corresponded with the difference in chemical shift between the two non-equivalent spins and a second frequency, J, that was smaller and independent of magnetic field strength (J/2π = 0.7 Hz). (wikipedia.org)
  • signals
  • However, most commercial MR scanners are generally only capable of spectroscopy using the signals from pro- tons. (aapm.org)
  • These experiments are often used to assign specific resonance signals to specific atoms in an isotopically-enriched protein. (wikipedia.org)
  • metabolites
  • Therefore, it is sometimes referred to as dynamic MRS, event-related MRS or time-resolved MRS. A novel variant of fMRS is functional diffusion-weighted spectroscopy (fDWS) which measures diffusion properties of brain metabolites upon brain activation. (wikipedia.org)
  • atoms
  • This type of spectroscopy determines the physical and chemical properties of atoms or the molecules in which they are contained. (wikipedia.org)
  • The presence or absence of imino proton resonances, or of coupling between 15N atoms across a hydrogen bond, indicates the presence or absence of basepairing. (wikipedia.org)
  • early 1950s
  • The Purcell group at Harvard University and the Bloch group at Stanford University independently developed NMR spectroscopy in the late 1940s and early 1950s. (wikipedia.org)
  • The first DNP experiments were performed in the early 1950s at low magnetic fields but until recently the technique was of limited applicability for high-frequency, high-field NMR spectroscopy, because of the lack of microwave (or terahertz) sources operating at the appropriate frequency. (wikipedia.org)
  • protein
  • Protein NMR Spectroscopy. (wikipedia.org)
  • Protein nuclear magnetic resonance is performed on aqueous samples of highly purified protein. (wikipedia.org)
  • Many of these experiments have since become the standard set of experiments used for sequential assignment of NMR resonances in the determination of protein structure by NMR. (wikipedia.org)
  • The early method of structural determination of protein by NMR relied on proton-based homonuclear NMR spectroscopy in which the size of the protein that may be determined is limited to ~10 KDa. (wikipedia.org)
  • Some of the experiments are used in tandem for the resonance assignment of protein, for example HNCACB may be used together with CBCA(CO)NH as a pair of experiments. (wikipedia.org)
  • He is a member of the United States National Academy of Sciences, a NIH Distinguished Investigator, and the Chief of the Protein NMR Spectroscopy Section in the Laboratory of Chemical Physics of the National Institute of Diabetes and Digestive and Kidney Diseases at the National Institutes of Health. (wikipedia.org)
  • He has remained at the NIH ever since and is currently an NIH Distinguished Investigator and Chief of the Section on Protein NMR Spectroscopy at the NIH. (wikipedia.org)
  • metabolism
  • Extension of these investigations into the realm of human myocardial metabolism has been made possible by the advent of relatively high-field magnets with spectroscopy capabilities and sufficient bore dimensions to allow human studies. (valorebooks.com)
  • frequency
  • The resonant frequency, energy of the absorption, and the intensity of the signal are proportional to the strength of the magnetic field. (wikipedia.org)
  • The selection rules of NMR spectroscopy dictate that ΔI = 1, which means that a given photon (in the radio frequency range) can affect ("flip") only one of the two nuclear spins. (wikipedia.org)
  • chemical
  • We set a constraint on molecular PNC in 13 C chemical shifts at a level of 10 -5 ppm, and provide a discussion of important considerations in the search for molecular PNC using NMR spectroscopy. (osti.gov)
  • It relies on the phenomenon of nuclear magnetic resonance and can provide detailed information about the structure, dynamics, reaction state, and chemical environment of molecules. (wikipedia.org)
  • Because of the historic problems with chemical shift referencing, chemical shifts are perhaps the most precisely measurable but the least accurately measured parameters in all of NMR spectroscopy. (wikipedia.org)
  • consists
  • Structure determination by NMR spectroscopy usually consists of several phases, each using a separate set of highly specialized techniques. (wikipedia.org)
  • If the spin ensemble consists of a magnetic moment, a monotonic decay in the echo envelope is obtained. (wikipedia.org)
  • spectrum
  • Single Voxel Spectroscopy (SVS): has a minimum spatial resolution of approximately 1 cm3, and has the cleanest spectrum free from unwanted artefacts due to the small acquired volume. (wikipedia.org)
  • Owing to rapid spin relaxation, the electron-nuclear coupling is not observed in the NMR spectrum, so the affected nuclear resonance appears at the average of the two coupled energy states, weighted according to their spin populations. (wikipedia.org)
  • diffusion
  • Whereas, measurements of diffusion constants (diffusion ordered spectroscopy or DOSY) are done the sample stationary and spinning off, and flow cells can be used for online analysis of process flows. (wikipedia.org)
  • known
  • Magnetic resonance spectroscopy (MRS), also known as nuclear magnetic resonance (NMR) spectroscopy, is a non-invasive, ionizing-radiation-free analytical technique that has been used to study metabolic changes in brain tumors, strokes, seizure disorders, Alzheimer's disease, depression and other diseases affecting the brain. (wikipedia.org)
  • Multi-voxel spectroscopy usually is performed when the specific volume of interest is not known or it is important to study metabolite dynamics in a larger brain region. (wikipedia.org)
  • It is useful for molecules of up to 100 nucleotides, and as of 2003, nearly half of all known RNA structures had been determined by NMR spectroscopy. (wikipedia.org)
  • spins
  • Note that the alignment of electron spins at a given magnetic field and temperature is described by the Boltzmann distribution under the thermal equilibrium. (wikipedia.org)
  • field
  • In many such applications it is desirable to provide a system that can produce a magnetic field having the required intensity, distribution and stability for high-resolution analytical spectroscopic applications. (google.com)
  • Modern NMR spectrometers have a very strong, large and expensive liquid helium-cooled superconducting magnet, because resolution directly depends on magnetic field strength. (wikipedia.org)
  • These steps include: Shimming the magnetic field: this step is taken to correct for the inhomogeneity of the magnetic field by tuning different pulses in the x, y, and z directions. (wikipedia.org)
  • This anisotropy creates a magnetic field which supplements that of the instrument's magnet. (wikipedia.org)
  • The magnetic field exerts its effect with both angular and a 1/r3 geometric dependences. (wikipedia.org)
  • The signal to noise ratio for 1H is about 300 fold greater than 15N at the same magnetic field. (wikipedia.org)
  • To balance the need for temporal resolution and sufficient SNR, fMRS requires a high magnetic field strength (1.5 T and above). (wikipedia.org)