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NMR measurements of the resonance frequency on YBCO indicated that electrons in the copper oxide superconductors are paired in spin-singlet states.
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NMR and measurements
Nuclear magnetic resonance ( NMR ) measurements
Tacticity measurements obtained by Carbon-13 NMR are typically expressed in terms of the relative abundance of various pentads within the polymer molecule, e. g. mmmm, mrrm.
NMR measurements probe the local magnetic field around an atom and hence reflect the susceptibility of the material.
In the anisotropic HTS, perhaps NMR measurements have found that the relaxation rate for copper depends on the direction of the applied static magnetic field, with the rate being higher when the static field is parallel to one of the axes in the copper oxide plane.
Experimentally, pK < sub > a </ sub > values can be determined by potentiometric ( pH ) titration, but for values of pK < sub > a </ sub > less than about 2 or more than about 11, spectrophotometric or NMR measurements may be required due to practical difficulties with pH measurements.
The < sup > 13 </ sup > C polarization levels in solid compounds can reach up to ≈ 64 % and the losses during dissolution and transfer of the sample for NMR measurements can be minimized to a few percent .< ref > Compounds containing NMR-sensitive nuclei can also be hyperpolarized using chemical reactions with para-hydrogen.
On August 14, 1996, Wetterhahn was studying the way mercury ions interact with DNA repair proteins and was using dimethylmercury as a standard reference material for < sup > 199 </ sup > Hg NMR measurements.
The < sup > 31 </ sup > P MAS NMR revealed predominately Q0 species ; i. e., PO < sub > 4 </ sub >< sup > 3 -</ sup >; subsequent MAS NMR spectroscopy measurements have shown that Si-O-P bonds are below detectable levels
NMR and resonance
Nuclear magnetic resonance ( NMR ) is a technique by which external magnetic fields can be used to find resonance modes of individual electrons, thus giving information about the atomic, molecular and bond structure of their neighborhood.
MRI makes use of the property of nuclear magnetic resonance ( NMR ) to image nuclei of atoms inside the body.
In a 1971 paper in the journal Science, Dr. Raymond Damadian, an Armenian-American physician, scientist, and professor at the Downstate Medical Center State University of New York ( SUNY ), reported that tumors and normal tissue can be distinguished in vivo by nuclear magnetic resonance (" NMR ").
* Nuclear magnetic resonance ( NMR )
Nuclear magnetic moments are important in other contexts, particularly in nuclear magnetic resonance ( NMR ) and magnetic resonance imaging ( MRI ).
* Nuclear magnetic resonance ( NMR ) spectroscopy is the most commonly used technique, often permitting complete assignment of atom connectivity and even stereochemistry using correlation spectroscopy.
Common methods are infra-red ( IR ) spectroscopy and nuclear magnetic resonance ( NMR ) spectroscopy.
* Nuclear magnetic resonance on molecules in solution ( liquid-state NMR ) ( qubit provided by nuclear spins within the dissolved molecule )
Nuclear magnetic resonance ( NMR ) spectroscopy is a widely used resonance method and ultrafast laser methods are also now possible in the infrared and visible spectral regions.
The diagram at left shows a typical nuclear magnetic resonance ( NMR ) spectrum of a borane molecule.
Lipscomb investigated, "... the carboranes, C < sub > 2 </ sub > B < sub > 10 </ sub > H < sub > 12 </ sub >, and the sites of electrophilic attack on these compounds using nuclear magnetic resonance ( NMR ) spectroscopy.
For comparison, the nearest competing method in terms of structures analyzed is nuclear magnetic resonance ( NMR ) spectroscopy, which has resolved 9561 chemical structures.
Resonance phenomena occur with all types of vibrations or waves: there is mechanical resonance, acoustic resonance, electromagnetic resonance, nuclear magnetic resonance ( NMR ), electron spin resonance ( ESR ) and resonance of quantum wave functions.
Nuclear magnetic resonance ( NMR ) is the name given to a physical resonance phenomenon involving the observation of specific quantum mechanical magnetic properties of an atomic nucleus in the presence of an applied, external magnetic field.
NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging ( MRI ).
NMR and frequency
A key feature of NMR is that the resonant frequency of a particular substance is directly proportional to the strength of the applied magnetic field.
Proton precession magnetometers, also known as proton magnetometers, PPMs or simply mags, measure the resonance frequency of protons ( hydrogen nuclei ) in the magnetic field to be measured, due to nuclear magnetic resonance ( NMR ).
The frequency of Earth's field NMR ( EFNMR ) for protons varies between approximately 900 Hz near the equator to 4. 2 kHz near the geomagnetic poles.
For liquid samples, the susceptibility can be measured from the dependence of the NMR frequency of the sample on its shape or orientation.
: 42. 6 MHz of the < sup > 1 </ sup > H nucleus frequency, in NMR.
The Knight shift refers to the relative shift K in NMR frequency for atoms in a metal ( e. g. sodium ) compared with the same atoms in a nonmetallic environment ( e. g. sodium chloride ).
Nuclear magnetic resonance decoupling in nuclear magnetic resonance ( NMR ) spectroscopy is a method of simplifying resulting spectrum by irradiating the sample at a certain frequency or frequency range to eliminate fully or partially the effect of coupling between certain nuclei.
In nuclear magnetic resonance ( NMR ) spectroscopy, the chemical shift is the resonant frequency of a nucleus relative to a standard.
Thus, an NMR signal that absorbs at 300 Hz higher than does TMS at an applied frequency of 300 MHz has a chemical shift of:
Absorption bands in the radio frequency range are found in NMR spectroscopy.
This is the fundamental basis for NMR, and in practice is accomplished by scanning until the resonant frequency is found at which point the sample will emit light.
Experimental background Anisotropic interactions modify the nuclear spin energy levels ( and hence the resonance frequency ) of all sites in a molecule, and often contribute to a line-broadening effect in NMR spectra.
The metatellurate anion has a chemical shift around 610 ppm when analyzed using < sup > 125 </ sup > Te NMR at 25 ° C at a frequency of 94. 735 MHz and referenced externally against aqueous 1. 0 M telluric acid.
This time-domain signal is typically digitised and then Fourier transformed in order to obtain a frequency spectrum of the NMR signal i. e. the NMR spectrum.
Particularly if a limited number of frequency components are present, the FID may be analysed directly for quantitative determinations of physical properties, such as hydrogen content in aviation fuel, solid and liquid ratio in dairy products ( Time-Domain NMR ).
NMR and on
Whereas < sup > 1 </ sup > H NMR spectroscopy is, in general, not useful for establishing the presence of a ketone, < sup > 13 </ sup > C NMR spectra exhibit signals somewhat downfield of 200 ppm depending on structure.
In each of these materials, the anisotropic nature of the pairing is implicated by the power-law dependence of the nuclear magnetic resonance ( NMR ) relaxation rate and specific heat capacity on temperature.
The Nilgiri Mountain Railway | Nilgiri passenger train ( NMR ) on the rack section
In April 1999 English Heritage merged with the Royal Commission on the Historical Monuments of England ( RCHME ) and the National Monuments Record ( NMR ), bringing together resources for the identification and survey of England ’ s historic environment.
The data, typically obtained by X-ray crystallography or NMR spectroscopy and submitted by biologists and biochemists from around the world, are freely accessible on the Internet via the websites of its member organisations ( PDBe, PDBj, and RCSB ).
Several applications rely on the use of double vacuum flasks, such as NMR and MRI machines.
These methods can be used for two or more sequences and typically produce local alignments ; however, because they depend on the availability of structural information, they can only be used for sequences whose corresponding structures are known ( usually through X-ray crystallography or NMR spectroscopy ).
The technology is based on a nuclear magnetic resonance ( NMR ) machine, which is similar to the medical magnetic resonance imaging machine.
** First execution of Grover's algorithm on an NMR computer.
* 2004 – First working pure state NMR quantum computer ( based on parahydrogen ) demonstrated at Oxford University and University of York.
After returning to Switzerland, Wüthrich collabrated with among others nobel laureate Richard R. Ernst on developing the first 2 dimensional NMR experiments, and established the nuclear Overhauser effect as a convenient way of measuring distances within proteins.
The NMR signal of protons in the plane of an aromatic ring are shifted substantially further down-field than those on non-aromatic sp² carbons.
The objective is develop models which can be used to predict properties of interest based on measured properties of the chemical system, such as pressure, flow, temperature, infrared, Raman, NMR spectra and mass spectra.
When he was drafted into the Army in the 1950s, his superiors allowed him to spend his time working on an early nuclear magnetic resonance ( NMR ) machine ; he had published four scientific papers by the time he left the Army.
While Lauterbur conducted his work at Stony Brook, the best NMR machine on campus belonged to the chemistry department ; he would have to visit it at night to use it for experimentation and would carefully change the settings so that they would return to those of the chemists ' as he left.
Targets for structure prediction are either structures soon-to-be solved by X-ray crystallography or NMR spectroscopy, or structures that have just been solved ( mainly by one of the structural genomics centers ) and are kept on hold by the Protein Data Bank.
Often thought of as a hybrid between quantum dot and NMR quantum computers, the Kane computer is based on an array of individual phosphorus donor atoms embedded in a pure silicon lattice.
Structure-based drug design ( or direct drug design ) relies on knowledge of the three dimensional structure of the biological target obtained through methods such as x-ray crystallography or NMR spectroscopy.
The mechanism is assumed to be a free-radical chain reaction, and the product, based on NMR spectra, is thought to be polycyclopropane.
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