Mapping experience

Hydrodynamic, Electrodynamic and Thermodynamic Transport in Porous Model Objects Magnetic Resonance Mapping Experiments and Simulations... 

Fig. 2.9.7 Hahn spin-echo rf pulse sequence combined with bipolar magnetic field gradient pulses for hydrodynamic-dispersion mapping experiments. The lower left box indicates field-gradient pulses for the attenuation of spin coherences by incoherent displacements while phase shifts due to coherent displacements on the time scale of the experiment are compensated. The box on the right-hand side represents the usual gradient pulses for ordinary two-dimensional imaging. The latter is equivalent to the sequence shown in Figure 2.9.2(a).

The advantages of imaging (using multichannel detectors or global imaging methods) over conventional mapping experiments are obvious, whenever multicomponent samples have to be investigated ... 

The easiest way to detect a protein modification seems to be the mass measurement of all peptides generated by enzymatic digestion. The comparison with the predicted peptide masses from the sequence of the protein identifies unmodified peptides and unexplained masses would give indications to modified peptides. Unfortunately, this is not a suitable approach in practice. In many peptide mapping experiments done with the MALDI mass mapping technique, up to 30% of the measured masses remain unexplained. This is probably due to protein contaminations from human keratins, chemical modifications introduced by gel electrophoresis and the digestion procedure, and other proteins present at low levels in the piece excised from the sodium dodecyl sulfate gel. The detection of a protein modification requires a more specific analysis. 

The only experiment flown up to the present, which specifically uses infrared information to probe the lower troposphere is the Measurement of Air Pollution from Satellites (MAPS) experiment. MAPS is a nadir sounding gas correlation instrument, which makes global measurements of CO in the middle and upper troposphere. It flew three times between 1981 and 1994 on the NASA Space Shuttle (Reichle et al., 1986 1990 Connors etal., 1991). Validation of MAPS was made using ground-based passive remote sensing instruments (Pougatchev et al., 1998). 

Intramolecular electron-transfers through peptides have also been observed by Isied and coworkers using Ru(NH3)5 modified cytochrome c 55). Because of the kinetic inertness of both the ruthenium(II) and ruthenium(III), NMR and other physical techniques can be used to characterize the point of attachment of the ruthenium center. NMR and peptide mapping experiments showed that the ruthenium is bound to the His-33 site of cyt c (Fig. 2). The reduction potentials are +0.26 V for cyt c and +0.07 V for [(NH3)5Ru(His)]2 +. Upon reduction of the Ru(III)-cyt c(III) derivative with 1 equiv. of electrons, any Ru(II)-cyt c(III) produced should undergo... 

To elucidate the contribution of the different histological structures to the average Raman spectral signatures from intact pollen grains, we conducted spatially resolved measurements on sections of rye pollen grains. Such mapping experiments can help separation of predominant spectral contributions from different substructures. 

Boston, USA). For the plots of the intensities as a function of spatial coordinate, after baseline correction, the areas under the respective bands were calculated. Figure 4.2 shows results of four examples of mapping experiments. 

PeptideMass (ExPASy Proteomic tools), which is designed for use in peptide mapping experiments, determines the cleavage products of a protein after exposure to a specific protease or chemical reagent. The enzymes and reagents available for cleavage via PeptideMass are trypsin, chymotrypsin, Lys C, cyanogen bromide, Arg C, Asp N, and Glu C. 

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