scholarly journals Peptide and Protein Dynamics and Low-Temperature/DNP Magic Angle Spinning NMR

2017 ◽  
Vol 121 (19) ◽  
pp. 4997-5006 ◽  
Author(s):  
Qing Zhe Ni ◽  
Evgeny Markhasin ◽  
Thach V. Can ◽  
Björn Corzilius ◽  
Kong Ooi Tan ◽  
...  
Keyword(s):  
Low Temperature ◽  
Protein Dynamics ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Angle Spinning

scholarly journals Thermometers for low temperature Magic Angle Spinning NMR

2010 ◽  
Vol 204 (1) ◽  
pp. 169-172 ◽  
Author(s):  
T.F. Kemp ◽  
G. Balakrishnan ◽  
K.J. Pike ◽  
M.E. Smith ◽  
R. Dupree
Keyword(s):  
Low Temperature ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Angle Spinning

scholarly journals Surface-Only Spectroscopy for Diffusion-Limited Systems Using Ultra-Low Temperature DNP MAS NMR at 16.4 T

2020 ◽  
Author(s):  
Yoh Matsuki ◽  
Tomoaki Sugishita ◽  
Toshimichi Fujiwara
Keyword(s):  
Low Temperature ◽  
Crystal Surface ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Standard Samples ◽  
Diffusion Limited ◽  
Crystal Core ◽  
Angle Spinning ◽  
Group Rotations

Conventional dynamic-nuclear-polarization (DNP) technique at T ~100 K can enhance sensitivity of magic-angle spinning (MAS) NMR over 100-fold for standard samples containing urea/proline at high-field conditions, B0= 9.4–16.4 T. In the scene of real applications, however, the achievable enhancement is often much lower than for urea/proline due to faster 1H relaxation (T1H) promoted by molecular-segmental fluctuations and methyl-group rotations active even at low temperatures, hindering an efficient polarization diffusion within the system. Here, we show at 16.4 T that ultra-low temperature (T≪100 K) provides a general way to improve the DNP efficiency for such diffusion-limited systems as we demonstrate on microcrystalline sample of a tripeptide N-f-MLF-OH. In a further step, the hyperpolarization localized at the crystal surface enabled “surface-only” spectroscopy eliminating background signals from the crystal core. The surface-only data, rather than the currently popular surface-enhanced data, should prove to be useful in many applications in biological and material sciences.

scholarly journals The Effect of Storage-Induced Changes in Ammonia Borane on Hydrogen Release during Its Low-Temperature Thermolysis

Inorganics ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 96 ◽  
Author(s):  
Oxana V. Komova ◽  
Olga V. Netskina ◽  
Anna M. Ozerova ◽  
Galina V. Odegova ◽  
Sergei S. Arzumanov ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Low Temperature ◽  
Ammonia Borane ◽  
Analysis Data ◽  
Magic Angle Spinning ◽  
Attenuated Total Reflection ◽  
Hydrogen Release ◽  
Magic Angle ◽  
Apparent Activation Energies ◽  
Angle Spinning

In this paper, low-temperature solid-state processes of the dehydrogenation of ammonia borane (NH3BH3, AB) samples of different purity are compared under the conditions of isothermal heating at 100 °C, as well as in the course of thermal analysis which was also carried out at different rates of heating. The composition of boron-containing impurities was studied by attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR) and 11B magic angle spinning nuclear magnetic resonance (11B MAS NMR). Accumulation in AB of three- and four-coordinated borate anions upon contact of hydride with air moisture is established. The apparent activation energies were calculated from thermal analysis data, and found to decrease from 174 to 163 kJ/mol as the AB purity decreased from 93% to 79%. This showed itself in a shortening of the induction period during the AB thermolysis under isothermal conditions. The prospects of using the thermal analysis for estimating NH3BH3 reactivity are discussed.

A strategem for low-temperature magic-angle spinning using nitrogen spinning gas

1985 ◽  
Vol 65 (1) ◽  
pp. 159-161 ◽  
Author(s):  
R.D Kenrick ◽  
S Friedrich ◽  
B Wehrle ◽  
H.H Limbach ◽  
C.S Yannoni
Keyword(s):  
Low Temperature ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Angle Spinning
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