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I have good news! With a minimal simplification of my INADEQUATE filter I have been able to rescue the last cross-peak of cholesterol. It had been rejected because too near to the diagonal. I changed the code saying: "if it's on the diagonal, it is bad; if it's just near, let's accept it". So it is possible to have the perfect INADEQUATE of cholesterol, with all the expected cross-peaks IN and everything else OUT. Yesterday I received another INADEQUATE spectrum, this time of sucrose. The S/N is still high enough to make my filter unnecessary. If I play with the contour plot all the noise disappears while the 12 carbon atoms and their 10 bonds remain. Only a spurious peak remains at the coordinates 103.7;-22.9. I have not received the 1-D external projection, so I created it artificially. The spectral width is the same in both dimension (instead of being doubled for the DQF axis). The consequence is that two cross-peaks fall just on the boundary and are partially ...

One of the most ancient 2-D experiments has always been more talked about than practiced. The INADEQUATE was invented 30 years ago (an era in which many chemists were still using CW-NMR) and has always been regarded as a the future thing, like travels to the Moon. Everybody agrees it is useful, but the experimental difficulties are discouraging. The information that can be extracted by this experiment is a formidable aid to unveil the structure of unknown natural compounds. For a long time, however, the experiment has been nearly impossible. You needed a powerful transmitter, because the nominal 180� pulse must be a true 180� pulse over a large spectral width. You also needed a sensitive probe. A cryo-probe is the best. Today we can have both things. I am not mentioning here the many attempts to increase the actual sensitivity with experimental tricks, because this is a blog about software. 19 years ago the S/N limit was overcome by a pure numerical method, see this paper , commerciali...