In the online parenting world, NMR stands for "Not mum related" and is usually written at the beginning of a Facebook post where a mum asks for advice on a topic that wouldn't normally be deemed to relate specifically to motherhood. In fact, they are so frequent that they really beg the question: what ISN'T mother related? Questions about house renovations, car specs, tax issues When so many mums worry about things that are "not mum related", surely they're at least a bit "mum related"?
Women, in their vast majority, are responsible for running the entirety of the household, many of them while juggling full-time jobs outside the home. The list of invisible tasks is as long as the day is short and, even on the rare occasion when the actual job itself falls on the man, it does so after extensive hours of research on the subject by a woman. Who's the national expert in trampolines in New Zealand?
I bet you it's a mum. Who's the number 1 expert in car seats? I guarantee you it's a mum. Who knows all there is to know about the different ranges of household cleaners and their effects on the skin?
Who is the best source of information on allergens? Best places to go on a family holiday? Ask a mum. MIchael B. Nuclear magnetic resonance spectroscopy NMR. Nuclear magnetic resonance spectroscopy , most commonly known as NMR spectroscopy or magnetic resonance spectroscopy MRS , is a spectroscopic technique to observe local magnetic fields around atomic nuclei. DIPSI: Decoupling or mixing sequence The DIPSI element decoupling in the presence of scalar interactions is sequence of pulses clustered together that serve to transfer magnetisation between protons that share scalar couplings.
The multi-pulse element is applied as a repeated sequence to define a total "mixing time" during which magnetisation is allowed to flow between coupled spins.
The diffusion coefficients are determined from the NMR signal intensity decays in a sequence of 1D spectra recorded with increasing amplitudes of pulsed field gradients PFGs which are used to map the translational behaviour of the solutes. The method can, for example, be employed to investigate molecular size, complexation phenomena, binding and aggregation.
The method is quick and clean, typically providing complete suppression of all other signals. Thus, so-called transient NOEs are sampled with this method and percentage NOE enhancements are not recorded directly nor do thay have the same significance as in the 1D NOE difference experiment. The gradient selection generally provides superior quality data in considerably less time than the traditional NOE difference method. This aims to propagate magnetisation from the selected proton to others within the same scalar-ccoupled spin-system and is therefore very useful for the analysis of the proton spectra of isolated systems such as amino-acids and saccharides.
The double-quantum filter serves to alter the phase properties of the spectrum, enabling a phase-sensitive presentation and thus higher resolution. In practice this aids the analysis of crowded spectra, reducing cross-peak overlap, and allows the potentially informative fine-structure within cross-peaks to be studied in detail. The filter also suppresses singlets in the spectrum along the diagonal.
Excitation sculpting: A method for the selective exciation or removal of a resonance or resonances in a spectrum based on the use of a sequence of pulsed field gradient spin-echoes, the best known example being the " double pulsed field gradient spin-echo " sequence. The method provides very clean excitation or removal of the target resonance s and may be used in selective 1D experiments or in solvent suppression methods, for example.
EXSY: Exchange Spectroscopy A homonuclear 2D method used to identify equilibrium chemical exchange pathways and, in favourable cases, quantify the kinetic processes.
Its appearance is similar to the basic COSY experiment, but crosspeaks now indicate an exchange process between the correlated spins. Its use is limited to those systems in which the exchange kinetics are faster than, or comparable to, spin relaxation rates. Most often used in the study of fluxional inorganic or organometallic systems, but can be applied to conformational exchange in organic systems, for example.
GARP: Broadband Decoupling Sequence The GARP globally-optimised, alternating-phase, rectangular pulses element is a cluster of pulses applied repeatedly to a heteroatom to achieve spin-decoupling, typically between protons and the irradiated heteroatom so called "heteronuclear decoupling". Commonly it is used for carbon decoupling in the HSQC experiment whilst proton magnetisation is detected, leading to decoupling of the observed 13C satellites.
The sequence is effective over a very wide spectral width, as required for carbon decoupling. Most often employed to correlate carbons with their directly bonded protons.
This rather old experiment makes use of carbon detection, and has nowadays largely been superseded by more sensitive proton detected heteronuclear shift correlation experiments such as HMQC and HSQC. HETCOR may, however, still find use when very high carbon resolution is required, since this is easier to achieve in the directly observed dimension of a 2D experiment. The experiment utilises proton detection so has good sensitivity, and benefits considerably from the use of pulsed field gradients.
It is an extremely powerful tool for piecing together organic structures, and is now a routine technique in organic chemistry. Utilises proton detection and has very high sensitivity and can be quicker to acquire than a 1D carbon spectrum. The correlations can be used to map known proton assignments onto their directly attached carbons.
The 2D spectrum can also prove useful in the assignment of the proton spectrum itself by dispersing the proton resonances along the 13C dimension and so reducing proton multiplet overlap. It also provides a convenient way of identifying diastereotopic geminal protons which are sometimes difficult to distinguish unambiguously, even in COSY since only these will produce two correlations to the same carbon.
This relays the original proton-carbon correlation peak onto neighbouring protons within the same spin-system, thus producing a 13C-dispersed TOCSY spectrum. This proves useful when analysing complex proton spectra for which the 2D TOCSY becomes too crowded for unambiguous interpretation.
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