Friday, January 29, 2016

Almost 1000 articles published for #DNPNMR spectroscopy in 2015

Dynamic Nuclear Polarization (DNP) enhanced NMR spectroscopy has gained tremendous interest in recent years. At least that is what we, the scientist in this research area, like to think. However, is it true? One way to find out is to look at the number of research papers published in the area. I love data mining and below is the result of my latest analysis.


Although DNP was known from the early days of magnetic resonance, it took a long time for the methodology to find its way into the scientific repertoire. This is mainly due to the increased technical difficulties to develop the required double-resonance instrumentation, with frequencies that are almost three orders of magnitude apart.

In the 1960s and 1970s low-field (0.35 T, 9 GHz e-, 14 MHz 1H) solution and solid-state DNP spectroscopy was successfully used to study molecular motions. However, microwave technology could not keep up with the rapid pace at which NMR spectroscopy was moving to higher magnetic field strengths. As a consequence interest in DNP spectroscopy remained low until the early 1990s.

This changed dramatically in 1993 with the introduction of the gyrotron as a reliable, high-frequency, high-power microwave source by Griffin and Temkin et al. Also with the increased interest in high-field Electron Paramagnetic Resonance (EPR) spectroscopy, more microwave and THz components becoming available, and the introduction of the dissolution-DNP experiment by Ardenkær-Larsan et al. in 2003.

Today, commercial equipment for DNP-NMR spectroscopy is available at NMR frequencies between 300 and 800 MHz (1H NMR), and the interest in DNP, as seen in the number of articles published in the area, has increased exponentially. So far 2015 has seen the most publications in the area, let's see if this trend will continue.


Note: This analysis is done using Google Scholar searching for the keywords "Dynamic Nuclear Polarization" and "Dynamic Nuclear Polarisation" excluding patents. All raw data are available upon request. Earlier studies using Scopus (Elsevier) have shown similar trends.

Wednesday, January 27, 2016

Measuring absolute spin polarization in dissolution-DNP by Spin PolarimetrY Magnetic Resonance (SPY-MR)


Vuichoud, B., et al., Measuring absolute spin polarization in dissolution-DNP by Spin PolarimetrY Magnetic Resonance (SPY-MR). J. Magn. Reson., 2015. 260: p. 127-135.


Dynamic nuclear polarization at 1.2 K and 6.7 T allows one to achieve spin temperatures on the order of a few millikelvin, so that the high-temperature approximation ( Δ E < kT) is violated for the nuclear Zeeman interaction Δ E = γB0h/(2 π ) of most isotopes. Provided that, after rapid dissolution and transfer to an NMR or MRI system, the hyperpolarized molecules contain at least two nuclear spins I and S with a scalar coupling JIS, the polarization of spin I (short for ‘investigated’) can be determined from the asymmetry AS of the multiplet of spin S (short for ‘spy’), provided perturbations due to second-order (strong coupling) effects are properly taken into account. If spin S is suitably discreet and does not affect the relaxation of spin I, this provides an elegant way of measuring spin polarizations ‘on the fly’ in a broad range of molecules, thus obviating the need for laborious measurements of signal intensities at thermal equilibrium. The method, dubbed Spin PolarimetrY Magnetic Resonance (SPY-MR), is illustrated for various pairs of 13 C spins (I, S) in acetate and pyruvate.

Monday, January 25, 2016

Experimental tests of a 263 GHz gyrotron for spectroscopic applications and diagnostics of various media


Glyavin, M.Y., et al., Experimental tests of a 263 GHz gyrotron for spectroscopic applications and diagnostics of various media. Review of Scientific Instruments, 2015. 86(5): p. 054705.


A 263 GHz continuous-wave (CW) gyrotron was developed at the IAP RAS for future applications as a microwave power source in Dynamic Nuclear Polarization / Nuclear magnetic resonance(DNP/NMR) spectrometers. A new experimental facility with a computerized control was built to test this and subsequent gyrotrons. We obtained the maximum CW power up to 1 kW in the 15 kV/0.4 A operation regime. The power about 10 W, which is sufficient for many spectroscopicapplications, was realized in the low current 14 kV/0.02 A regime. The possibility of frequencytuning by variation of the coolant temperature about 4 MHz/1 °C was demonstrated. The spectral width of the gyrotron radiation was about 10−6.

Friday, January 22, 2016

Closed-cycle cold helium magic-angle spinning for sensitivity-enhanced multi-dimensional solid-state NMR


Matsuki, Y., et al., Closed-cycle cold helium magic-angle spinning for sensitivity-enhanced multi-dimensional solid-state NMR. J Magn Reson, 2015. 259: p. 76-81.


Magic-angle spinning (MAS) NMR is a powerful tool for studying molecular structure and dynamics, but suffers from its low sensitivity. Here, we developed a novel helium-cooling MAS NMR probe system adopting a closed-loop gas recirculation mechanism. In addition to the sensitivity gain due to low temperature, the present system has enabled highly stable MAS (vR=4-12 kHz) at cryogenic temperatures (T=35-120 K) for over a week without consuming helium at a cost for electricity of 16 kW/h. High-resolution 1D and 2D data were recorded for a crystalline tri-peptide sample at T=40 K and B0=16.4 T, where an order of magnitude of sensitivity gain was demonstrated versus room temperature measurement. The low-cost and long-term stable MAS strongly promotes broader application of the brute-force sensitivity-enhanced multi-dimensional MAS NMR, as well as dynamic nuclear polarization (DNP)-enhanced NMR in a temperature range lower than 100 K.

Wednesday, January 20, 2016

Direct dynamic nuclear polarization targeting catalytically active (27)Al sites


Lund, A., et al., Direct dynamic nuclear polarization targeting catalytically active (27)Al sites. Phys Chem Chem Phys, 2015. 17(38): p. 25449-54.


Here we present a systematic study of direct (27)Al Dynamic Nuclear Polarization (DNP) as induced by three different mono-radical probes with side groups of varying charge states. By employing 4-amino TEMPO that adsorbs to negatively charged surface sites of Al-SBA-15, we achieve a (27)Al signal enhancement factor of approximately 13 compared to a signal enhancement factor of approximately 3-4 from mono-radicals that do not adsorb as strongly to the surfaces of Al-SBA-15, here 4-carboxy- and 4-hydroxy-TEMPO. By performing Electron Spin Echo Envelope Modulation (ESEEM) experiments and continuous wave (cw) Electron Paramagnetic Resonance (EPR) lineshape analysis using various nitroxide probes imbibed in Al-SBA-15, we find that direct (27)Al DNP enhancements achieved with different spin probes can be attributed to proximity and local concentration of the spin probes to aluminum on the surface of mesoporous alumina-silica.

Tuesday, January 19, 2016

[NMR] Inaugural workshop for the Nottingham DNP MAS NMR Facility, UK

From the Ampere Magnetic Resonance List

Inaugural workshop for the Nottingham DNP MAS NMR Facility

To mark the official opening of the Nottingham DNP MAS NMR Facility a Workshop will take place focusing on the current state of research involving DNP MAS NMR spectroscopy.

The workshop will be held on Monday, 18th July, 2016 in the School of Physics and Astronomy, University of Nottingham.

The following speakers have already agreed to present their work at the workshop:

Prof R. Griffin, MIT, Boston, USA
Prof L. Emsely, EPFL, Lausanne, Switzerland
Prof M. Baldus, Bijvoet Center for Biomolecular Research, Utrecht, Netherlands
Prof C. Glaubitz, J.W. Goethe Universität, Frankfurt, Germany
Dr D. Lee, CEA, Grenoble, France
Dr F. Engelke, Bruker

The programme will start at 10:00 and end at 18:00 hours.

Attendance at the workshop will be free. However for the sake of planning catering we ask attendees to register using a brief form on the Facility webpage ( http://www.nottingham.ac.uk/dnpnmr )

We are looking forward welcoming you to Nottingham in July 2016

Subhradip Paul (Facility Manager)
Boyan Bonev (Life Science)
Jeremy Titman (Chemistry)
Walter Kockenberger (Physics and Astronomy)

====================================
This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database:

Friday, January 15, 2016

Carbon and proton Overhauser DNP from MD simulations and ab initio calculations: TEMPOL in acetone


Kucuk, S.E., T. Biktagirov, and D. Sezer, Carbon and proton Overhauser DNP from MD simulations and ab initio calculations: TEMPOL in acetone. Phys Chem Chem Phys, 2015. 17(38): p. 24874-84.


A computational analysis of the Overhauser effect is reported for the proton, methyl carbon, and carbonyl carbon nuclei of liquid acetone doped with the nitroxide radical TEMPOL. A practical methodology for calculating the dynamic nuclear polarization (DNP) coupling factors by accounting for both dipole-dipole and Fermi-contact interactions is presented. The contribution to the dipolar spectral density function of nuclear spins that are not too far from TEMPOL is computed through classical molecular dynamics (MD) simulations, whereas the contribution of distant spins is included analytically. Fermi contacts are obtained by subjecting a few molecules from every MD snapshot to ab initio quantum mechanical calculations. Scalar interaction is found to be an essential part of the (13)C Overhauser DNP. While mostly detrimental to the carbonyl carbon of acetone it is predicted to result in large enhancements of the methyl carbon signal at magnetic fields of 9 T and beyond. In contrast, scalar coupling is shown to be negligible for the protons of acetone. The additional influence of proton polarization on the carbon DNP (three-spin effect) is also analyzed computationally. Its effect, however, is concluded to be practically insignificant for liquid acetone.

[NMR] postdoctoral position in solid-state NMR in Strasbourg/France

Postdoctoral Position: Solid-state NMR of Membrane-Associated Polypeptides

The laboratory Membrane Biophysics and NMR at the University of Strasbourg has an opening for a postdoctoral position with experience in using solid-state NMR methods in the structural analysis of membrane proteins. The aim of the project is to reveal the structural determinants that define the highly specific lipid recognition motif of some transmembrane proteins (cf. Nature 2012, 481:525 and BBA 2014, 1838:2066) and to characterize changes in structure, dynamics and topology of the protein domains as well as the lipids during recognition.

Candidates should have good experience in MAS solid-state NMR and be ready to also include oriented membrane samples in the structural analysis (e.g. PNAS 2009, 106, 16639). Knowledge of solution NMR approaches, peptide synthesis and/or the biochemical production of proteins are of advantage. S/he should have a strong background in biological NMR, a good publication record and an interest in working in a highly interdisciplinary, international and collaborative environment. The project and position are funded by a three-year international grant from the French National Agency for Research (ANR) in collaboration with the DFG/University of Heidelberg. The University of Strasbourg chemistry, life sciences and structural biology departments having excellent scientific records, with a multitude of collaborations world-wide.

Strasbourg is a very nice city on the French side of the Rhine river, at the border to Germany, with easy access to nearby mountains (Vosges, Black Forrest, Alps). Being in the heart of Europe it takes only short train rides to multiple destinations of scientific and/or touristic interest.

Candidates should send their CV, publication list and contact info for three references to:

Prof. Burkhard Bechinger,

************************
Burkhard Bechinger

Professeur
Membrane Biophysics and NMR
Chemistry Institute UMR7177
University of Strasbourg/CNRS
International Center for Frontier Research in Chemistry
4, rue Blaise Pascal, Institut Le Bel 4.34 (NEW, we moved)
F-67008 Strasbourg

Tel: + 33 3 68 85 13 03

Joint Meeting of the French and German Biophysical Societies
Biophysics of Protein-Membrane Interactions: From Model Systems to Cells
11-14 April 2016, www.bpmi-badherrenalb.de

secreatrial office: 
Tel: + 33 3 68 85 17 34 
FAX: + 33 3 68 85 17 35 


====================================
This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database:

Wednesday, January 13, 2016

PhD Studentship – Applications of large-scale NMR, EPR and MRI simulations

PhD Studentship – Applications of large-scale NMR, EPR and MRI simulations

PhD Supervisor: Ilya Kuprov
Application Deadline: 01 June 2016 
Project Description:

A fully funded three-year PhD studentship, starting on 1 Oct 2016, is available in the Quantum Spin Dynamics research group at the Chemistry Department of the University of Southampton. The studentship includes EU level university fees and a tax-free stipend of £13,863 per annum.

The research project deals with fundamental theories of magnetic interactions in chemical systems, with applications to magnetic resonance spectroscopy and medical imaging. In particular, the project will contribute to the development of large-scale theoretical modelling tools that offer unprecedented insight into quantum mechanical processes that underpin magnetic phenomena in chemical and biological systems.

Our recent work on the matter includes spin dynamics processes in photosynthetic reaction systems, hypothetical magnetic field sensing mechanisms in migratory birds, magnetic contrast agents for medical imaging and bio-molecular magnetic resonance spectroscopy.

The School of Chemistry at the University of Southampton is one of the finest chemistry departments in the UK, renowned especially for its work in crystallography, electrochemistry and magnetic resonance. In particular the Biological NMR Centre within Chemistry hosts a 600 MHz NMR spectrometer equipped with a state-of-the-art cold probe, as well as 400 MHz and 600 MHz instruments equipped with a range of MAS solid state probes. In addition, there are four wide-bore NMR spectrometers between 300 MHz and 600 MHz, equipped for cryogenic MAS, microimaging and DNP experiments.

University of Southampton supercomputing facilities are among the best in the country – Iridis3 and Iridis4 clusters have, between them, over 2000 nodes equipped with Intel Nehalem CPUs and over 50 TB of aggregate memory. Dedicated NVidia and Intel Xeon Phi compute nodes are available, as are high-memory nodes equipped with 256 GB of RAM. Iridis4 in particular is the most powerful academic supercomputer in England, the second largest academic computational facility in the UK (behind the National Facility), in Top 15 academic computational facilities in Europe and in Top 30 academic computational facilities in the world.

Due to funding restrictions this position is only open to UK applicants

Applications should be submitted online.

Enquiries should be addressed to Dr Ilya Kuprov (i.kuprov@soton.ac.uk). Further information on the research carried out by the Spin Dynamics group is available at http://spindynamics.org; any queries on the application process should be made to pgafnes@soton.ac.uk

-----------------------------------------
Dr Ilya Kuprov FRSC
Associate Professor of Chemical Physics
Office 3041, Building 30,
School of Chemistry, FNES,
University of Southampton,
Southampton, SO17 1BJ, UK.
Tel: +44 2380 594 140
-----------------------------------------



====================================
This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database:

Non-aqueous solvents for DNP surface enhanced NMR spectroscopy


Zagdoun, A., et al., Non-aqueous solvents for DNP surface enhanced NMR spectroscopy. Chem Commun (Camb), 2012. 48(5): p. 654-6.


A series of non-aqueous solvents combined with the exogenous biradical bTbK are developed for DNP NMR that yield enhancements comparable to the best available water based systems. 1,1,2,2-tetrachloroethane appears to be one of the most promising organic solvents for DNP solid-state NMR. Here this results in a reduction in experimental times by a factor of 1000. These new solvents are demonstrated with the first DNP surface enhanced NMR characterization of an organometallic complex supported on a hydrophobic surface.

Monday, January 11, 2016

One hundred fold overall sensitivity enhancements for Silicon-29 NMR spectroscopy of surfaces by dynamic nuclear polarization with CPMG acquisition


Rossini, A.J., et al., One hundred fold overall sensitivity enhancements for Silicon-29 NMR spectroscopy of surfaces by dynamic nuclear polarization with CPMG acquisition. Chem. Sci., 2012. 3(1): p. 108-115.


Dynamic nuclear polarization (DNP) 29Si solid-state NMR spectra of a hybrid mesoporous silica material impregnated with aqueous biradical solutions have been acquired with cross-polarization (CP) and cross-polarization Carr-Purcell Meiboom-Gill (CP/CPMG) pulse sequences. The integrated intensities (II) and signal to noise ratios (S/N) of the 29Si solid-state NMR spectra are monitored in order to measure the DNP enhancement factors (?Si[space]CP) as well as the overall sensitivity enhancement ([capital Sigma]Si[space]CP) available from the combination of DNP and CPMG acquisition. Here, , where [small theta]Si is a factor which quantifies reduction of the NMR signal by paramagnetic effects (quenching) and [small kappa] is the square root of the ratio of nuclear longitudinal relaxation times of the dry material and material impregnated with radical solution. It is found that [capital Sigma]Si[space]CP is always substantially lower than the measured value of ?Si[space]CP due to paramagnetic effects which reduce the II of the 29Si CP solid-state NMR spectra at high biradical concentrations. In this system, it is observed that the sample preparation which provides optimal DNP signal enhancement does not provide optimal overall signal enhancement. Notably, optimal signal enhancements are obtained for CPMG acquisition of the 29Si solid-state NMR spectra when lower radical concentrations are employed due to slower transverse relaxation rates. To the best of our knowledge this is the first study which seeks to quantify the overall sensitivity enhancements available from DNP solid-state NMR experiments.

Friday, January 8, 2016

#VnmrJ is now open source

I'm very pleased to learn that VnmrJ is now open source. The project is hosted on GitHub and detailed information is accessible through:

http://openvnmrj.org

Before you want to change to the OpenVnmrJ you should read this:

http://openvnmrj.org/about/#spectrometer-users-read-this


BDPA-Doped Polystyrene Beads as Polarization Agents for DNP-NMR


Polarizing agents are typically dispersed in glass forming solvents to avoid clustering of the radicals which can lead to strong exchange interaction resulting in poor DNP efficiency. Therefore glycerol (or DMSO) is often added to the aqueous solution.

These polarizing beads are very interesting because they potentially allow DNP using solvents that do not inherently form a glass. It would be really interesting to see how efficient this approach is for TEMPO based radicals. In addition these beads allow optimizing the local environment of the radical (for example to optimize relaxation properties) for optimum DNP performance independently from the sample properties.



Zhang, Y., P.J. Baker, and L.B. Casabianca, BDPA-Doped Polystyrene Beads as Polarization Agents for DNP-NMR. J Phys Chem B, 2015.


The aromatic free radical BDPA (alpha,gamma-bisdiphenylene-beta-phenylallyl), which has been widely used as a polarizing agent for Dynamic Nuclear Polarization (DNP) of hydrophobic analytes, has been incorporated into nanometer-scale polystyrene latex beads. We have shown that the resulting BDPA-doped beads can be used to hyperpolarize 13C and 7Li nuclei in aqueous environments, without the need for a glassing cosolvent. DNP enhancement factors of between 20 and 100 were achieved with overall BDPA concentrations of 2 mM or less. These Highly-Effective Polymer/Radical Beads (HYPR-beads) have potential use as an inexpensive polarizing agent for water-soluble analytes, and also have applications as model nanoparticles in DNP studies.

Wednesday, January 6, 2016

Demonstration of open-quantum-system optimal control in dynamic nuclear polarization


Sheldon, S. and D.G. Cory, Demonstration of open-quantum-system optimal control in dynamic nuclear polarization. Physical Review A, 2015. 92(4): p. 042102.


Dynamic nuclear polarization (DNP) is used in nuclear magnetic resonance (NMR) to transfer polarization from electron spins to nuclear spins. The resulting nuclear polarization enhancement can, in theory, be two or three orders of magnitude depending on the sample. In solid state systems, however, there are competing mechanisms of DNP, which, when occurring simultaneously, reduce the net polarization enhancement of the nuclear spin. We present a simple quantum description of DNP and apply optimal control theory (OCT) with an open quantum system framework to design pulses that select one DNP process and suppress the others. We demonstrate experimentally an order of magnitude improvement in the DNP enhancement using OCT pulses.

[NMR] PhD or early PostDoc position in hyperpolarized MR

From the Ampere Magnetic Resonance List


We have one open position for an early stage researcher (ESR) in the Dept. of Prof. Hennig in the Hyperpolarization group of Jan-Bernd Hövener in Freiburg, Germany. The position is part of the ITN "EuroPOL" and includes secondments to partners abroad as well as participation in other international meetings.

Topic
The topic is on novel developments in hyperpolarized MR, likely with a focus on MRI sequence development and training in methods to polarize 13C metabolic tracers with parahydrogen. Furthermore, the applicant will gain first-hand experience and knowledge in running MRI experiments. It is a great oportunity to start or advance your scientific carrier and to build an international network!

Program
The international training network (ITN) - program EUROPOL (www.europol-itn.eu) is running for three years. The payment is well above the average for an equivalent position in Germany. Employment beyond that may be extended (on different funding). For more information on the group and our acitivities, see http://www.hyperpolarization.net. The Hennig department is a large, international group currently hosting 85+ members from 7+ nationalities. The hyperpolarization group has currently 7 members; - become No. 7!

Formal Requirements
A qualified applicant can not hold a PhD degree at the time of employment and can not have lived in Germany for more than 12 month in the last three years.

Contact
We would like to fill the position ASAP, - please apply with a CV at jan.hoevener@uniklinik-freiburg.de or call + 49 761 270 93910

Many thanks!
Jan

__________________________________________________
Dr. Jan-Bernd Hövener
Head of Hyperpolarization
Emmy Noether Project – Molecular and Metabolic MRI

University Medical Center Freiburg
Department of Radiology
Medical Physics
Breisacher Str. 60a
D - 79106 Freiburg

phone: +49 761 270 93910
fax: +49 761 270 38310
__________________________________________________

====================================
This is the AMPERE MAGNETIC RESONANCE mailing list:

NMR web database:

Top 3 Articles for #DNPNMR in December 2015

These are the top three most viewed blog posts for December 2015 from our DNP blog:



Monday, January 4, 2016

Microwave frequency modulation to enhance Dissolution Dynamic Nuclear Polarization


Bornet, A., et al., Microwave frequency modulation to enhance Dissolution Dynamic Nuclear Polarization. Chem. Phys. Lett., 2014. 602: p. 63-67.


Hyperpolarization by Dissolution Dynamic Nuclear Polarization is usually achieved by monochromatic microwave irradiation of the ESR spectrum of free radicals embedded in glasses at 1.2 K and 3.35 T. Hovav et al. (2014) have recently shown that by using frequency-modulated (rather than monochromatic) microwave irradiation one can improve DNP at 3.35 T in the temperature range 10–50 K. We show in this Letter that this is also true under Dissolution-DNP conditions at 1.2 K and 6.7 T. We demonstrate the many virtues of using frequency-modulated microwave irradiation: higher polarizations, faster build-up rates, lower radical concentrations, less paramagnetic broadening, more efficient cross-polarization, and less critical frequency adjustments.