NMR Prediction in Mnova follows the concept of “unity creates strength”. The basic idea is to combine several predictors together to get a better predictive power. We have borrowed from the field of Machine Learning the term "ensemble" to define this new prediction procedure and I have written about it in this article, “Ensemble NMR Prediction” , where some results using 13C NMR data are given.
To complement that article, in this post I will show some results for 1H NMR data. I have taken from the literature a few assigned molecules. Those molecules were not contained in the internal databases of Mnova predictors. The overall results are shown in table 1.
Table 1: Mean absolute errors for the individual and ensemble predictor. ML stands for Machine Learning
As in the 13C analysis, the new Ensemble Prediction provides a smaller MAE than the individual predictors.
The error distribution also shows that the ensemble method helps reduce the number of prediction outliers
Table 2: Distribution of prediction errors for the different individual predictors as well as for the final, ensemble result. Freq. values are in %.
[NMR paper] Acidity Strength of Solid Catalysts Probed by Hyperpolarized Natural Abundance 17O NMR Spectroscopy
Acidity Strength of Solid Catalysts Probed by Hyperpolarized Natural Abundance 17O NMR Spectroscopy
Observation of Brønsted acid sites: By enhancing the solid-state NMR signals of 17O at natural abundance with dynamic nuclear polarization (DNP), Pruski et al. were able to measure oxygen–proton distances accurately with sub-picometer precision. The results give insight into the Brønsted acidity of a range of solid acid catalysts.
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nmrlearner
Journal club
0
07-11-2017 09:20 AM
Non-equilibrium hydrogen exchange for determination of H-bond strength and water accessibility in solid proteins
Non-equilibrium hydrogen exchange for determination of H-bond strength and water accessibility in solid proteins
Abstract
We demonstrate measurement of non-equilibrium backbone amide hydrogenâ??deuterium exchange rates (HDX) for solid proteins. The target of this study are the slowly exchanging residues in solid samples, which are associated with stable secondary-structural elements of proteins. These hydrogen exchange processes escape methods measuring equilibrium exchange rates of faster processes. The method was applied to a micro-crystalline...
nmrlearner
Journal club
0
04-10-2017 12:51 AM
[NMR images] unlike proton nmr spectroscopy the relative strength of carbon nmr
http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/nmr/Images/ccamphor.gif
3/06/2014 10:43:59 AM GMT
unlike proton nmr spectroscopy the relative strength of carbon nmr
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nmrlearner
NMR pictures
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06-03-2014 10:43 AM
[Question from NMRWiki Q&A forum] Gradient strength recalculation
Gradient strength recalculation
Iam bit stuck with % z gradient calculation used in Bruker pulse programs. In some instruments (Varian) they use as short as 200us for some gradient pulses, but in Bruker, they fix the length of all the gradient pulses as constant (say 500 us) and vary the gradient strength accordingly.
Hence, is there any easy way to convert a gradient pulse of say 17 G/cm applied for 0.5 ms to 'x' G/cm for 1ms.(where 'x' is the new gradient strength for 1ms).
Once this conversion is completed,the next step would be to calculate the gradient % which i think is the...
[Question from NMRWiki Q&A forum] How do you port pulse sequences to different field strength?
How do you port pulse sequences to different field strength?
Hi, when you set up a pulse sequence at a different magnet field strength - starting with an existing set of parameters - what do you look at?
Does length of shaped pulses always need to be changed?
What pulse lenghts need to be adjusted?
When it is necessary to re-build RF waveforms - for what kinds of pulses?
nmrlearner
News from other NMR forums
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08-22-2010 02:30 AM
[NMRwiki tweet] nmrwiki: How do you port #NMR pulse sequences to different field strength? #spectrosc
nmrwiki: How do you port #NMR pulse sequences to different field strength? #spectroscopy http://qa.nmrwiki.org/question/148/
nmrwiki: How do you port #NMR pulse sequences to different field strength? #spectroscopy http://qa.nmrwiki.org/question/148/
Source: NMRWiki tweets