Monday, December 13, 2010

3rd International Meeting on DNP, Sept. 7th-10th 2011, Lausanne, CH

Mark your calendars, the 3rd International Meeting on Dynamic Nuclear Polarization (DNP) will be held September 7th - 10th, 2011, at EPFL Lausanne, Switzerland, following the highly successful meetings in Nottingham (2007) and Koenigstein (2009). The preliminary program comprises 24 speakers and can be downloaded from:


The dates of the meeting have been chosen so that the participants may elect to move from Lausanne to nearby Chamonix, where the 7th Alpine Conference on solid-state NMR will take place in the following week, September 11th - 5th, 2011.

SBIR Grant Awarded to Bridge12

First SBIR Grant for Commercialization of Dynamic Nuclear Polarization Awarded to Bridge12 for it's Terahertz Research

 

Bridge12 Develops New Compact Gyrotron To Accelerate NMR Experiments
by Several Orders of Magnitude

Cambridge, Mass. – October 25, 2010 – Bridge12 Technologies (Bridge12), a leading provider of terahertz technology for applications in science, medicine, security and defense, today announces it has received the first small business innovation research (SBIR) grant for the commercialization of dynamic nuclear polarization (DNP) enhanced nuclear magnetic resonance (NMR) spectroscopy. DNP accelerates experiments that typically require several weeks to be performed in minutes.

Friday, December 10, 2010

Theoretical Aspects of Dynamic Nuclear Polarization in the Solid State - The Solid Effect

Y. Hovav et al., Theoretical Aspects of Dynamic Nuclear Polarization in the Solid State - The Soild Effect, J. Magn. Reson., 2010, 207(2), 176-189


Dynamic nuclear polarization has gained high popularity in recent years, due to advances in the experimental aspects of this methodology for increasing the NMR and MRI signals of relevant chemical and biological compounds. The DNP mechanism relies on the microwave (MW) irradiation induced polarization transfer from unpaired electrons to the nuclei in a sample. In this publication we present nuclear polarization enhancements of model systems in the solid state at high magnetic fields.

Linearly Polarized Modes of a Corrugated Waveguide

E.J. Kowalski et al., Linearly Polarized Modes of a Corrugated Waveguide, IEEE Trans. on Mic. Theo. and Tech., 2010, 58(11), 2772-2780


A linearly polarized $({rm LP}_{mn})$ mode basis set for oversized, corrugated, metallic waveguides is derived for the special case of quarter-wavelength-depth circumferential corrugations. The relationship between the ${rm LP}_{mn}$ modes and the conventional modes $({rm HE}_{mn},{rm EH}_{mn},{rm TE}_{0n},{rm TM}_{0n})$ of the corrugated guide is shown.

Solid-State NMR Spectroscopy on Complex Biomolecules

M. Renault et al., Solid-State NMR Spectroscopy on Complex Biomolecules, Ang. Chem. Int. Ed., 2010, 49(45), 8346-8357


Biomolecular applications of NMR spectroscopy are often merely associated with soluble molecules or magnetic resonance  imaging. However, since the late 1970s, solid-state NMR (ssNMR) spectroscopy has demonstrated its ability to provide atomic-level insight into complex biomolecular systems ranging from lipid bilayers to complex biomaterials. In the last decade, progress in the areas of NMR spectroscopy, biophysics, and molecular biology have significantly expanded the repertoire of ssNMR spectroscopy for biomolecular studies. This Review discusses current approaches and methodological challenges, and highlights recent progress in using ssNMR spectroscopy at the interface of structural and cellular biology.

Dynamic Nuclear Polarization of Deuterated Proteins

U. Akbey, Dynamic Nuclear Polarization of Deuterated Proteins, Angew. Chem. Int. Ed., 2010, 49(42), 7803-7806


Magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy has evolved as a robust and widely applicable technique for investigating the structure and dynamics of biological systems. It is in fact rapidly becoming an indispensable tool in structural biology studies of amyloid, nanocrystalline, and membrane proteins. However, it is clear that the low sensitivity of MAS experiments to directly detected 13C and 15N signals limits the utility of the approach, particularly when working with systems which are difficult to obtain in large quantities.

Surface Enhanced NMR Spectroscopy by Dynamic Nuclear Polarization

A. Lesage et al., Surface enhanced NMR Spectroscopy by Dynamic Nuclear Polarization, J. Am. Chem. Soc., 2010, 132(44), 15459-15461

http://dx.doi.org/10.1021/ja104771z

It is shown that surface NMR spectra can be greatly enhanced using dynamic nuclear polarization. Polarization is transferred from the protons of the solvent to the rare nuclei (here carbon-13 at natural isotopic abundance) at the surface, yielding at least a 50-fold signal enhancement for surface species covalently incorporated into a silica framework.

EPR detected polarization transfer between GD3+ and protons at low temperature and 3.3T: The first step of dynamic nuclear polarization

Nagarajan V. et al., EPR detected polarization transfer between Gd3+ and protons at low temperature and 3.3 T: The first step of dynamic nuclear polarization, J. Chem. Phys., 2010, 132, 214504


Electron-electron double resonance pulsed electron paramagnetic resonance (EPR) at 95 GHz (3.3 T) is used to follow the dynamics of the electron spin polarization during the first stages of dynamic nuclear polarization in solids. The experiments were performed on a frozen solution of Gd+3 (S=7/2) in water/glycerol. Focusing on the central |−1/2>→|+1/2> transition we measured the polarization transfer from the Gd3+ electron spin to the adjacent 1H protons.

High Field Dynamic Nuclear Polarization - The Renaissance

An entire issues dedicated to recent developments in high-field Dynamic Nuclear Polarization (DNP) and it's application to enhance NMR signal intensities published by the Royal Society of Chemistry (UK) in Physical Chemistry Chemical Physics, Issue 22.

Dynamic Nuclear Polarization in III–V Semiconductors

G. Kaur and G. Denninger, Dynamic Nuclear Polarization in III-V Semiconductors, Appl. Magn. Reson., 2010, 39(1-2), 185-204


We report on electron spin resonance, nuclear magnetic resonance and Overhauser shift experiments on two of the most commonly used III–V semiconductors, GaAs and InP. Localized electron centers in these semiconductors have extended wavefunctions and exhibit strong electron–nuclear hyperfine coupling with the nuclei in their vicinity. These interactions not only play a critical role in electron and nuclear spin relaxation mechanisms, but also result in transfer of spin polarization from the electron spin system to the nuclear spin system.

Amplification of Picosecond Pulses in a 140-GHz Gyrotron-TravelingWave Tube

H.J. Kim et al., Amplification of Picosecond Pulses in a 140-GHz Gyrotron Travelling Wave Tube, Phys. Rev. Lett., 105(13), 135101-135104


An experimental study of picosecond pulse amplification in a gyrotron-traveling wave tube (gyro- TWT) has been carried out. The gyro-TWT operates with 30 dB of small signal gain near 140 GHz in the HE06 mode of a confocal waveguide. Picosecond pulses show broadening and transit time delay due to two distinct effects: the frequency dependence of the group velocity near cutoff and gain narrowing by the finite gain bandwidth of 1.2 GHz.

Hyperpolarizing Gases via Dynamic Nuclear Polarization and Sublimation

A. Comment et al., Hyperpolarizing Gases via Dynamic Nuclear Polarization and Sublimation, Phys. Rev. Lett., 2010, 105(1), 018104-018107.


A high throughput method was designed to produce hyperpolarized gases by combining low temperature dynamic nuclear polarization with a sublimation procedure. It is illustrated by applications to 129Xe nuclear magnetic resonance in xenon gas, leading to a signal enhancement of 3 to 4 orders of magnitude compared to the room-temperature thermal equilibrium signal at 7.05 T.

High-Field Dynamic Nuclear Polarization for Solid and Solution Biological NMR

A.B. Barnes et al., High-Field Dynamic Nuclear Polarization for Solid and Solution Biological NMR, Appl. Magn. Reson., 2008, 4(3), 237-263.


Dynamic nuclear polarization (DNP) results in a substantial nuclear polarization enhancement through a transfer of the magnetization from electrons to nuclei. Recent years have seen considerable progress in the development of DNP experiments directed towards enhancing sensitivity in biological nuclear magnetic resonance (NMR). This review covers the applications, hardware, polarizing agents, and theoretical descriptions that were developed at the Francis Bitter Magnet Laboratory at Massachusetts Institute of Technology for high-field DNP experiments.

Dynamic Nuclear Polarization at High Magnetic Fields

Thorsten Maly et al., Dynamic nuclear polarization at high magnetic fields, J. Chem. Phys., 2008, 128(5), 052211-19

http://dx.doi.org/10.1063/1.283358

Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (μw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (γe/γl), being ∼ 660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields.