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  • 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)
  • nuclei
  • The sample is placed in a magnetic field and the NMR signal is produced by excitation of the nuclei sample with radio waves into nuclear magnetic resonance , which is detected with sensitive radio receivers. (wikipedia.org)
  • Even though MR imaging is an offshoot of MR spectroscopy, clinical medical physicists familiar with MRI may not be familiar with many of the common practical issues regarding MRS. Numerous research labora- tories perform in vivo MRS on other magnetic nuclei, such as 31P, 13C, and 19F. (aapm.org)
  • A course dealing with the quantum and classical description of the nuclear magnetic resonance of an isolated system of two spin-1/2 nuclei. (wustl.edu)
  • Most frequently, NMR spectroscopy is used by chemists and biochemists to investigate the properties of organic molecules, although it is applicable to any kind of sample that contains nuclei possessing spin. (wikipedia.org)
  • When placed in a magnetic field, NMR active nuclei (such as 1H or 13C) absorb electromagnetic radiation at a frequency characteristic of the isotope. (wikipedia.org)
  • It is common to refer to a 21 T magnet as a 900 MHz magnet, although different nuclei resonate at a different frequency at this field strength in proportion to their nuclear magnetic moments. (wikipedia.org)
  • This limitation is due to the need to assign NMR signals from the large number of nuclei in the protein - in larger protein, the greater number of nuclei results in overcrowding of resonances, and the increasing size of the protein also broadens the signals, making resonance assignment difficult. (wikipedia.org)
  • These triple resonance experiments utilize the relatively large magnetic couplings between certain pairs of nuclei to establish their connectivity. (wikipedia.org)
  • Sequential assignment using triple resonance experiments These experiments are typically named by the nuclei (H, N, and C) involved in the experiment. (wikipedia.org)
  • The Hamiltonian of a molecular system may be taken as: H = D1 + D2 + D3, D1 = electron orbital-orbital, spin-orbital, spin-spin and electron-spin-external-field interactions D2 = magnetic interactions between nuclear spin and electron spin D3 = direct interaction of nuclei with each other For a singlet molecular state and frequent molecular collisions, D1 and D3 are almost zero. (wikipedia.org)
  • The direct interaction between two magnetic dipoles depends on the relative position of two nuclei in such a way that when averaged over all possible orientations of the molecule it equals to zero. (wikipedia.org)
  • DNP is typically performed at low temperature (≈1 K) and high magnetic field (≈3 T). The compound is subsequently thawed and dissolved to yield a room temperature solution containing hyperpolarized nuclei. (wikipedia.org)
  • Compared to orthohydrogen or organic molecules, a much greater fraction of the hydrogen nuclei in parahydrogen align with an applied magnetic field. (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)
  • typically
  • 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)
  • Also, for some metastatic lesions and for high-grade gliomas, typically, there are resonances corresponding to lactate or lipids ( 26 , 27 ). (aacrjournals.org)
  • Hyperpolarized noble gases are typically used in magnetic resonance imaging (MRI) of the lungs. (wikipedia.org)
  • MRSI
  • Tumor-bearing mice are anesthetized by breathing isoflurane in a magnetic resonance (MR) scanner dedicated to small animal MR. Here we describe the overall setup and steps for measuring 1 H and 31 P MRS and 1 H MRSI of orthotopic breast tumor models in mice with surface coils. (springer.com)
  • biomolecular
  • He is known for his foundational work in three-dimensional protein and nucleic acid structure determination by biomolecular NMR spectroscopy, for advancing experimental approaches to the study of large macromolecules and their complexes by NMR, and for developing NMR-based methods to study rare conformational states in protein-nucleic acid and protein-protein recognition. (wikipedia.org)
  • molecules
  • Besides identification, NMR spectroscopy provides detailed information about the structure, dynamics, reaction state, and chemical environment of molecules. (wikipedia.org)
  • Nucleic acid NMR is the use of nuclear magnetic resonance spectroscopy to obtain information about the structure and dynamics of nucleic acid molecules, such as DNA or RNA . (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)
  • 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)
  • This type of spectroscopy determines the physical and chemical properties of atoms or the molecules in which they are contained. (wikipedia.org)
  • 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)
  • One of the great conveniences of NMR spectroscopy for organic molecules is that the many lighter elements are nearly monoisotopic: 1H, 19F, and 31P each have spin 1/2. (wikipedia.org)
  • paramagnetic
  • Pseudocontact shifts result from the magnetic field emanating from the paramagnetic center. (wikipedia.org)
  • The effect of the pseudocontact term arises magnetic anisotropy of the paramagnetic center (reflected in g-anisotropy in the EPR spectrum). (wikipedia.org)
  • experiment
  • 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)
  • spectrum
  • Pulse sequences are available that suppress specific peaks (e.g., water suppression) ( Fig. 2 ), that excite only resonances of interest, or that confine the MR signal to a specific volume (voxel), creating a localized spectrum ( Fig. 3 ). (diabetesjournals.org)
  • 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)
  • There is a tradition in diamond spectroscopy to label a defect-induced spectrum by a numbered acronym (e.g. (wikipedia.org)
  • atoms
  • These experiments are often used to assign specific resonance signals to specific atoms in an isotopically-enriched protein. (wikipedia.org)
  • sequential
  • The sequential walking methodology is not possible for non-double helical nucleic acid structures, nor for the Z-DNA form, making assignment of resonances more difficult. (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)
  • 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)
  • chemical
  • In many of the cases, it is possible to deduce full chemical structures from Nuclear Magnetic Resonance data. (hubpages.com)
  • 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)
  • 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)
  • frequency
  • The intramolecular magnetic field around an atom in a molecule changes the resonance frequency, thus giving access to details of the electronic structure of a molecule and its individual functional groups. (wikipedia.org)
  • In two-dimensional NMR , the emission is centered around a single frequency, and correlated resonances are observed. (wikipedia.org)
  • 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)
  • excitation
  • or exciting only resonances of interest ("selective excitation"), which has the additional, potentially undesired effect of distorting the peak amplitudes. (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)
  • 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)
  • 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)
  • 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)
  • Shimming
  • 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)