The Atomic-Level Structure of Cementitious Calcium Aluminate Silicate Hydrate Determined by NMR

We review our recent paper which resolves the long-standing dilemma of the location and nature of the six-fold coordinated aluminum in calcium aluminate silicate hydrate (C-A-S-H) samples. First principles calculations predict that at high Ca:Si and H2O ratios, aluminum is incorporated into the bridging sites of the linear silicate chains and that the stable coordination number is six. We confirm this hypothesis experimentally by one- and two-dimensional dynamic nuclear polarization enhanced 27 Al and 29 Si solid-state NMR experiments in which we correlate the distinctive six-fold coordinated aluminum NMR signal at 5 ppm to 29 Si NMR signals from silicates in C-A-S-H

Clearing the undergrowth: detection and quantification of low level impurities using 19F NMR

A new 19F NMR method, ODYSSEUS, allows low level impurities to be detected without interference from 13C satellites.</p

Hyperpolarization transfer pathways in inorganic materials

Dynamic nuclear polarization can be used to hyperpolarize the bulk of proton-free inorganic materials in magic angle spinning NMR experiments. The hyperpolarization is generated on the surface of the material with incipient wetness impregnation and from there it is propagated towards the bulk through homonuclear spin diffusion between weakly magnetic nuclei. This method can provide significant gains in sensitivity for MAS NMR spectra of bulk inorganic compounds, but the pathways of the magnetization transfer into the material have not previously been elucidated. Here we show how two-dimensional experiments can be used to study spin diffusion from the surface of a material towards the bulk. We find that hyperpolarization can be efficiently relayed from surface sites to multiple bulk sites simultaneously, and that the bulk sites also engage in rapid polarization exchange between themselves. We also show evidence that the surface peaks can exchange polarization between different sites in cases of disorder

Homonuclear Decoupling in H-1 NMR of Solids by Remote Correlation

The typical linewidths of H-1 NMR spectra of powdered organic solids at 111 kHz magic-angle spinning (MAS) are of the order of a few hundred Hz. While this is remarkable in comparison to the tens of kHz observed in spectra of static samples, it is still the key limit to the use of H-1 in solid-state NMR, especially for complex systems. Here, we demonstrate a novel strategy to further improve the spectral resolution. We show that the anti-z-COSY experiment can be used to reduce the residual line broadening of H-1 NMR spectra of powdered organic solids. Results obtained with the anti-z-COSY sequence at 100 kHz MAS on thymol, beta-AspAla, and strychnine show an improvement in resolution of up to a factor of two compared to conventional spectra acquired at the same spinning rate

CHORUS Oneshot: Experimental data and materials

A new pulse sequence, CHORUS Oneshot, allows measurement of diffusion-ordered spectroscopy (DOSY) spectra over the full chemical shift range of 19F for the first time. Frequency-swept pulses are used to give very broadband excitation and refocusing; the sequence is a prototype for a large family of very broadband liquid state NMR methods. Full experimental data, pulse sequences, pulse shapes are given in Bruker TopSpin format

C satellite-free H NMR spectra

Based on the results of previous research in the field of early home interventions in special education, we designed a programme for families with a profoundly physically disabled child. The programme “Rehabilitating toddlers from an educational perspective” is aimed at children between two and four years old, who attend toddler therapy sessions at a rehabilitation centre three or four mornings a week for treatment and counselling. The main goal of the programme is to prevent unnecessary developmental retardation in children with profound physical disabilities. Unnecessary retardation may occur due to the different, unfamiliar educational approach required of parents and educators. Educators’ typically intuitive approach will not work on these children because their profound physical disabilities impede an adequate response. This situation is referred to as an atypical educational situation, in which parental actions based on intuition, tradition or common sense do not suffice. When a child is treated in a rehabilitation centre, parents delegate part of their educational responsibility to careworkers in the centre. Careworkers thus become jointly responsible for the child’s education, although parents retain ultimate responsibility. A child participating in a toddler therapy group receives his or her education in three situations: at home, in the therapy group and during treatments. Each situation may make different, conflicting demands on the child. This may become confusing for the child and result in doubtfulness. In addition, treatment or stimulation effects may clash and parents’ educational questions may remain unanswered. These problems may be solved or prevented by tuning the education received at home and in the toddler therapy group. Such tuning could be achieved by offering parents early home intervention in special education (EHI), by treating the child and stimulating his or her development in toddler therapy groups and by training and coaching careworkers. These aspects are the main features of the programme “Rehabilitating toddlers from an educational perspective”.

Improving the detection and quantification of low level impurities using 19F NMR

Experimental data, pulse sequence source code, radiofrequency pulse shapes, macros and Mathematica notebooks for experiments to improve the detection and quantification of low level impurities using 19F NM