Radio frequency Subject

The sample is again subjected to a constant magnetic field but all the nuclei are excited by a very short radio frequency pulse. The frequency e (e.g., 400 MHz for a proton at 9.4 tesla) is applied over a period of several... 

Fourier transform spectroscopy in the radio frequency region has been applied most importantly in pulsed Fourier transform NMR spectroscopy, which is not a subject which... 

When fired electrically, fireworks are connected to wirebridge fuseheads. The fuseheads can inadvertently ignite if subjected to radio hazard (RAD HAZ) when in the vicinity of radio frequency sources such as cellular (mobile) telephones or walkie-talkie radios. Further advice on this should be sought from the makers of the wirebridge fuseheads and of the communication equipment because the characteristics of all these items can vary to some extent. 

If a spin system in thermal equilibrium with the lattice (i.e. that described by the vector p,) is subjected, immediately prior to the moment t = 0, to a strong radio-frequency pulse, then, after the pulse ceases, the vector corresponding to the density matrix of the system becomes (23,99)... 

Many different types of 3D and 4D experiments can be devised. We described briefly one class, in which two different kinds of 2D experiments are joined, primarily to use the third dimension to clarify the presentation of spectral data. With the ability of most modern NMR spectrometers to provide precise frequency and phase control for several radio frequencies simultaneously and to apply them efficiently in the probe, a class of 3D and 4D triple resonance experiments has become feasible. These experiments usually use two HSQC and/or HMQC sequences to transfer magnetization in the path I— S— T— S— I. I is almost always H 5 and T are 13C and 15N in proteins, the type of molecule in which these experiments are most often utilized. In addition,31P may be involved in nucleic acids, another frequent subject for these methods, and many other nuclides can be used in other applications. 

The physical basis of current MRI methods has its origin in the fact that, in a strong magnetic field, the nuclear spins of water protons in different tissues relax back to equilibrium at different rates, when subject to perturbation from the resting Boltzmann distribution by the application of a short radio frequency (rf) pulse. For the most common type of spin-echo imaging, return to equilibrium takes place in accord with equation 1 and is governed by two time constants T and T2, the longitudinal and transverse relaxation times, respectively. 

Three carbon fiber surfaces are compared in this study Amoco Thornel-300 graphitized at 2500 C, Hercules IM6 carbon fiber subjected to surface oxidation but with no subsequent deposition of size (oils, surfactants, or polymer films applied to facilitate manufacture and processing), and unsized IM6 treated with a radio frequency glow discharge plasma. 

Other Mass Analyzers. Other analyzers, such as quadrupole ion trap (QIP) and Fourier transform mass spectrometer (FTMS), are of some interest for proteomics. The quadrupole ion trap mass analyzer was devised by Wolfgang Paul it works on the principle of trapping ions with a particular RF in the quadrupole mass analyzer. This device provides a way to eject ions of certain radio frequency and retain the others, only the latter are allowed to reach the detector by scanning ions of a particular radio frequency. In this method, the selected ions can be subjected to fragmentation by collision-induced dissociation (CID), which is useful for the analysis of peptides. 

Memorandum, NATO, MAS.USA/151.97, 12 November 1997, subject STANAG MED (EDITION 2) - EVALUATION AND CONTROL OF PERSONNEL EXPOSURE TO RADIO FREQUENCY FIELDS - 3 KHz to 300 GHz. 

Actually, this suggestion serves to introduce the subjects of microwave and radio frequency radiation. RF radiation is being used to cure adhesives on laminates for furniture and for drying coatings, while microwave has been used to vulcanize rubber, convert plastics, and dry inks. 

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