Friday, April 29, 2016

Development and testing of hyperpolarized 13C MR calibrationless parallel imaging


Feng, Y., et al., Development and testing of hyperpolarized 13C MR calibrationless parallel imaging. J. Magn. Reson., 2016. 262: p. 1-7.


A calibrationless parallel imaging technique developed previously for 1H MRI was modified and tested for hyperpolarized 13C MRI for applications requiring large FOV and high spatial resolution. The technique was demonstrated with both retrospective and prospective under-sampled data acquired in phantom and in vivo rat studies. A 2-fold acceleration was achieved using a 2D symmetric EPI readout equipped with random blips on the phase encode dimension. Reconstructed images showed excellent qualitative agreement with fully sampled data. Further acceleration can be achieved using acquisition schemes that incorporate multi-dimensional under-sampling.

Wednesday, April 27, 2016

Dissolution DNP for in vivo preclinical studies


Comment, A., Dissolution DNP for in vivo preclinical studies. J Magn Reson, 2016. 264: p. 39-48.


The tremendous polarization enhancement afforded by dissolution dynamic nuclear polarization (DNP) can be taken advantage of to perform preclinical in vivo molecular and metabolic imaging. Following the injection of molecules that are hyperpolarized via dissolution DNP, real-time measurements of their biodistribution and metabolic conversion can be recorded. This technology therefore provides a unique and invaluable tool for probing cellular metabolism in vivo in animal models in a noninvasive manner. It gives the opportunity to follow and evaluate disease progression and treatment response without requiring ex vivo destructive tissue assays. Although its considerable potential has now been widely recognized, hyperpolarized magnetic resonance by dissolution DNP remains a challenging method to implement for routine in vivo preclinical measurements. The aim of this article is to provide an overview of the current state-of-the-art technology for preclinical applications and the challenges that need to be addressed to promote it and allow its wider dissemination in the near future.

Tuesday, April 26, 2016

[NMR] Summer school Theory of NMR at Colditz 4-10 Sept. 2016

From the Ampere Magnetic Resonance List



Call for the 2nd Summer school Theory of NMR at Colditz 4-10 Sept. 2016

Financed by the Volkswagen-Stiftung will be a summer school on the Theory of NMR at Youth hostel Schloss Colditz (50 km S/E of Leipzig/Germany) from Sun/4 (evening) to Sat/10 (morning) Sept. 2016.

The subjects of the school will focus on solids and relaxation. Topics to be covered: quantum mechanics for NMR, superoperators and Liouville space, coherent and dissipative evolution, solids and MAS, relaxation concepts, BPP and Redfield theories, slow motions in solids, Anderson-Weiss theory, polymer chain dynamics.


Teachers: Prof. Shimon Vega (Weizmann Institute of Science, Rechovot), Dr.
Konstantin Ivanov (International Tomography Center, Novosibirsk), Prof. Malcolm Levitt (Univ. Southampton), Prof. Madhu (TIFR Hyderabad), Prof. Kay Saalwächter (Univ. Halle-Wittenberg).
Organizer: Prof. Jörg Matysik (Univ. Leipzig).

Information on the youth hostel:

Participants of the first school are particularly encouraged to apply but the call is open to all PhD students and postdocs in the field.

Participation and accommodation will be entirely free.
Travel will be partially supported.
Max number of students = 45.
Deadline for application = 9 May 2016.
Decision on participation = within a month.

For application, please provide: (1) last name, (2) first name, (3) gender f/m,  (4) e-mail address, (5) country of laboratory, (6) institution/place, (7) head of laboratory, (8) food veg/nonveg/other, (9) arrival date, (10) departure date, (11) about three sentences describing your research project, (12) about three sentences on your motivation to participate, (13) any further information.

Send your e-mail to: zeller@chemie.uni-leipzig.de.

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NP 2016 summerschool August 22-26, organized by the EPFL and the PSI #DNPNMR

From the Ampere Magnetic Resonance List


Dear DNP Community

On behalf of the Organizing Committee it’s our pleasure to invite you to attend the next DNP School 2016, which will be held from August 22tnh to August 26th in Tramelan, a little Swiss village at 900 m elevation in the Bernese Jura close to Biel, Switzerland.

The School is addressed to PhD students and young researchers and focuses on theoretical and experimental aspects of dynamic nuclear polarization in the solid state. It is organized jointly by the EPFL (Lausanne) and the Paul Scherrer Institute (Villigen). It follows earlier schools in 2008 and 2012 held at PSI and will show new aspects.


The principles of dynamic nuclear polarization
A PhD-level summer school
Main lecturer

Prof. W. Th. Wenckebach

Invited lecturers
Prof. J. H. Ardenkjaer-Larsen, Technical University of Denmark
Prof. S. Vega, Weizmann Institute of Science
Prof. Matthew E. Merritt, The University of Florida

It is reachable by public transport from Zürich Airport, Basel Euro Airport and Lausanne in about 2 hours. The number of places is limited. Further information and a preregistration form is now available through the website:
http://sdnpi.epfl.ch/pdf/Summer_School_2016.pdf


We would appreciate it if you could kindly disseminate this information to others interested in the School.

With best regards,

The organizing committee
Patrick Hautle (PSI)
Ben van den Brandt (PSI)
Arnaud Comment (EPFL)

________________________________________________________
The principles of dynamic nuclear polarization
By prof W.Th. Wenckebach
A PhD-level summer school in Tramelan, Switzerland, 22-26 August 2016
Jointly organized by EPFL (Lausanne) and Paul Scherrer Institute (Villigen)
Email: dnpschool@psi.ch


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http://www.drorlist.com/nmrlist.html

NMR web database:
http://www.drorlist.com/nmr.html

Monday, April 25, 2016

Optimizing dissolution dynamic nuclear polarization


Bornet, A. and S. Jannin, Optimizing dissolution dynamic nuclear polarization. J Magn Reson, 2016. 264: p. 13-21.


This article is a short review of some of our recent developments in dissolution dynamic nuclear polarization (d-DNP). We present the basic principles of d-DNP, and motivate our choice to step away from conventional approaches. We then introduce a modified d-DNP recipe that can be summed up as follows.

Friday, April 22, 2016

On the present and future of dissolution-DNP


Ardenkjaer-Larsen, J.H., On the present and future of dissolution-DNP. J Magn Reson, 2016. 264: p. 3-12.


Dissolution-DNP is a method to create solutions of molecules with nuclear spin polarization close to unity. The many orders of magnitude signal enhancement have enabled many new applications, in particular in vivo MR metabolic imaging. The method relies on solid state dynamic nuclear polarization at low temperature followed by a dissolution to produce the room temperature solution of highly polarized spins. This work describes the present and future of dissolution-DNP in the mind of the author. The article describes some of the current trends in the field as well as outlines some of the areas where new ideas will make an impact. Most certainly, the future will take unpredicted directions, but hopefully the thoughts presented here will stimulate new ideas that can further advance the field.

Monday, April 18, 2016

Instrumentation for solid-state dynamic nuclear polarization with magic angle spinning NMR


Rosay, M., M. Blank, and F. Engelke, Instrumentation for solid-state dynamic nuclear polarization with magic angle spinning NMR. J Magn Reson, 2016. 264: p. 88-98.


Advances in dynamic nuclear polarization (DNP) instrumentation and methodology have been key factors in the recent growth of solid-state DNP NMR applications. We review the current state of the art of solid-state DNP NMR instrumentation primarily based on available commercial platforms. We start with a general system overview, including options for microwave sources and DNP NMR probes, and then focus on specific developments for DNP at 100K with magic angle spinning (MAS). Gyrotron microwave sources, passive components to transmit microwaves, the DNP MAS probe, a cooling device for low-temperature MAS, and sample preparation procedures including radicals for DNP are considered.

Friday, April 15, 2016

The phenomenology of optically pumped 13C NMR in diamond at 7.05 T: Room temperature polarization, orientation dependence, and the effect of defect concentration on polarization dynamics


Scott, E., M. Drake, and J.A. Reimer, The phenomenology of optically pumped 13C NMR in diamond at 7.05 T: Room temperature polarization, orientation dependence, and the effect of defect concentration on polarization dynamics. J. Magn. Reson., 2016. 264: p. 154-162.


Room temperature optical illumination of NV− imbibed single crystal diamonds with a 532 nm laser produces 13C polarization enhancements up to 200 times greater than that of the thermal equilibrium value at 7.05 T. We report high field NV− mediated 13C polarization as a function of the number and type (NV− and P1) of defects in commercially available diamonds. Surprisingly, both positive and negative 13C polarizations are observed depending on the orientation of the crystal with respect to the external magnetic field and the electric field vector of the optical illumination. The data reported herein cannot be explained by a previously proposed mechanism.

Wednesday, April 13, 2016

A versatile and modular quasi optics-based 200GHz dual dynamic nuclear polarization and electron paramagnetic resonance instrument


I know it's still early in the year, but this may be already my most favorite article for 2016.




Siaw, T.A., et al., A versatile and modular quasi optics-based 200GHz dual dynamic nuclear polarization and electron paramagnetic resonance instrument. J Magn Reson, 2016. 264: p. 131-53.


Solid-state dynamic nuclear polarization (DNP) at higher magnetic fields (>3T) and cryogenic temperatures ( approximately 2-90K) has gained enormous interest and seen major technological advances as an NMR signal enhancing technique. Still, the current state of the art DNP operation is not at a state at which sample and freezing conditions can be rationally chosen and the DNP performance predicted a priori, but relies on purely empirical approaches. An important step towards rational optimization of DNP conditions is to have access to DNP instrumental capabilities to diagnose DNP performance and elucidate DNP mechanisms. The desired diagnoses include the measurement of the "DNP power curve", i.e. the microwave (MW) power dependence of DNP enhancement, the "DNP spectrum", i.e. the MW frequency dependence of DNP enhancement, the electron paramagnetic resonance (EPR) spectrum, and the saturation and spectral diffusion properties of the EPR spectrum upon prolonged MW irradiation typical of continuous wave (CW) DNP, as well as various electron and nuclear spin relaxation parameters. Even basic measurements of these DNP parameters require versatile instrumentation at high magnetic fields not commercially available to date. In this article, we describe the detailed design of such a DNP instrument, powered by a solid-state MW source that is tunable between 193 and 201GHz and outputs up to 140mW of MW power. The quality and pathway of the transmitted and reflected MWs is controlled by a quasi-optics (QO) bridge and a corrugated waveguide, where the latter couples the MW from an open-space QO bridge to the sample located inside the superconducting magnet and vice versa. Crucially, the versatility of the solid-state MW source enables the automated acquisition of frequency swept DNP spectra, DNP power curves, the diagnosis of MW power and transmission, and frequency swept continuous wave (CW) and pulsed EPR experiments. The flexibility of the DNP instrument centered around the QO MW bridge will provide an efficient means to collect DNP data that is crucial for understanding the relationship between experimental and sample conditions, and the DNP performance. The modularity of this instrumental platform is suitable for future upgrades and extensions to include new experimental capabilities to meet contemporary DNP needs, including the simultaneous operation of two or more MW sources, time domain DNP, electron double resonance measurements, pulsed EPR operation, or simply the implementation of higher power MW amplifiers.

Monday, April 11, 2016

Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning


Thurber, K. and R. Tycko, Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning. J Magn Reson, 2016. 264: p. 99-106.


We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264GHz with 1.5W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized (13)C NMR signals in the 100-200 range are demonstrated with DNP at 25K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30K can be achieved with helium consumption rates below 1.3l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states.

Saturday, April 9, 2016

Meet Bridge12 at ENC in Pittsburgh #DNPNMR

Meet Bridge12 at this year's ENC in Pittsburgh from April 10th - 15th. This will be the first time that Bridge12 has a small booth, showcasing some of our products.

Thorsten Maly will also give a talk in the DNP Methods & Applications session on Thursday morning from 10:45-12:30pm in Grand 2. He will be presenting our shoebox-sized 263 GHz EPR spectrometer for DNP-NMR.

Hope to see you at ENC and please stop by at our booth to discuss your ideas for DNP-NMR spectroscopy. Our goal is to help you focusing on your research, not trouble-shooting home-built instrumentation.

Friday, April 8, 2016

Perspectives on DNP-enhanced NMR spectroscopy in solutions


van Bentum, J., et al., Perspectives on DNP-enhanced NMR spectroscopy in solutions. J Magn Reson, 2016. 264: p. 59-67.


More than 60years after the seminal work of Albert Overhauser on dynamic nuclear polarization by dynamic cross relaxation of coupled electron-nuclear spin systems, the quest for sensitivity enhancement in NMR spectroscopy is as pressing as ever. In this contribution we will review the status and perspectives for dynamic nuclear polarization in the liquid state. An appealing approach seems to be the use of supercritical solvents that may allow an extension of the Overhauser mechanism towards common high magnetic fields. A complementary approach is the use of solid state DNP on frozen solutions, followed by a rapid dissolution or in-situ melting step and NMR detection with substantially enhanced polarization levels in the liquid state. We will review recent developments in the field and discuss perspectives for the near future.

Thursday, April 7, 2016

DNP 2016 summerschool August 22-26, Tramelan, Switzerland, #DNPNMR



Dear DNP Community

On behalf of the Organizing Committee it’s our pleasure to invite you to attend the next DNP School 2016, which will be held from August 22tnh to August 26th in Tramelan, a little Swiss village at 900 m elevation in the Bernese Jura close to Biel, Switzerland.

The School is addressed to PhD students and young researchers and focuses on theoretical and experimental aspects of dynamic nuclear polarization in the solid state. It is organized jointly by the EPFL (Lausanne) and the Paul Scherrer Institute (Villigen). It follows earlier schools in 2008 and 2012 held at PSI and will show new aspects. 


The principles of dynamic nuclear polarization
A PhD-level summer school

Main lecturer
Prof. W. Th. Wenckebach

Invited lecturers
Prof. J. H. Ardenkjaer-Larsen, Technical University of Denmark
Prof. S. Vega, Weizmann Institute of Science
Prof. Matthew E. Merritt, The University of Texas Southwestern

It is reachable by public transport from Zürich Airport, Basel Euro Airport and Lausanne in about 2 hours.

The number of places is limited. Further information and a preregistration form is now available through the website: 

We would appreciate it if you could kindly disseminate this information to others interested in the School.

With best regards,

The organizing committee
Patrick Hautle (PSI)
Ben van den Brandt (PSI)
Arnaud Comment (EPFL)

________________________________________________________

The principles of dynamic nuclear polarization
By prof W.Th. Wenckebach
A PhD-level summer school in Tramelan, Switzerland, 22-26 August 2016
Jointly organized by EPFL (Lausanne) and Paul Scherrer Institute (Villigen)

Wednesday, April 6, 2016

Solid effect DNP polarization dynamics in a system of many spins


Wisniewski, D., et al., Solid effect DNP polarization dynamics in a system of many spins. J Magn Reson, 2016. 264: p. 30-8.


We discuss the polarization dynamics during solid effect dynamic nuclear polarization (DNP) in a central spin model that consists of an electron surrounded by many nuclei. To this end we use a recently developed formalism and validate first its performance by comparing its predictions to results obtained by solving the Liouville von Neumann master equation. The use of a Monte Carlo method in our formalism makes it possible to significantly increase the number of spins considered in the model system. We then analyse the dependence of the nuclear bulk polarization on the presence of nuclei in the vicinity of the electron and demonstrate that increasing the minimal distance between nuclei and electrons leads to a rise of the nuclear bulk polarization. These observations have implications for the design of radicals that can lead to improved values of nuclear spin polarization. Furthermore, we discuss the potential to extend our formalism to more complex spin systems such as cross effect DNP.

Monday, April 4, 2016

Dynamic nuclear polarization by frequency modulation of a tunable gyrotron of 260GHz


Yoon, D., et al., Dynamic nuclear polarization by frequency modulation of a tunable gyrotron of 260GHz. J Magn Reson, 2016. 262: p. 62-7.


An increase in Dynamic Nuclear Polarization (DNP) signal intensity is obtained with a tunable gyrotron producing frequency modulation around 260GHz at power levels less than 1W. The sweep rate of frequency modulation can reach 14kHz, and its amplitude is fixed at 50MHz. In water/glycerol glassy ice doped with 40mM TEMPOL, the relative increase in the DNP enhancement was obtained as a function of frequency-sweep rate for several temperatures. A 68 % increase was obtained at 15K, thus giving a DNP enhancement of about 80. By employing lambda/4 and lambda/8 polarizer mirrors, we transformed the polarization of the microwave beam from linear to circular, and achieved an increase in the enhancement by a factor of about 66% for a given power.

Friday, April 1, 2016

Spin polarization transfer mechanisms of SABRE: A magnetic field dependent study


Pravdivtsev, A.N., et al., Spin polarization transfer mechanisms of SABRE: A magnetic field dependent study. J Magn Reson, 2015. 261: p. 73-82.


We have investigated the magnetic field dependence of Signal Amplification By Reversible Exchange (SABRE) arising from binding of para-hydrogen (p-H2) and a substrate to a suitable transition metal complex. The magnetic field dependence of the amplification of the (1)H Nuclear Magnetic Resonance (NMR) signals of the released substrates and dihydrogen, and the transient transition metal dihydride species shows characteristic patterns, which is explained using the theory presented here. The generation of SABRE is most efficient at low magnetic fields due to coherent spin mixing at nuclear spin Level Anti-Crossings (LACs) in the SABRE complexes. We studied two Ir-complexes and have shown that the presence of a (31)P atom in the SABRE complex doubles the number of LACs and, consequently, the number of peaks in the SABRE field dependence. Interestingly, the polarization of SABRE substrates is always accompanied by the para-to-ortho conversion in dihydride species that results in enhancement of the NMR signal of free (H2) and catalyst-bound H2 (Ir-HH). The field dependences of hyperpolarized H2 and Ir-HH by means of SABRE are studied here, for the first time, in detail. The field dependences depend on the chemical shifts and coupling constants of Ir-HH, in which the polarization transfer takes place. A negative coupling constant of -7Hz between the two chemically equivalent but magnetically inequivalent hydride nuclei is determined, which indicates that Ir-HH is a dihydride with an HH distance larger than 2A. Finally, the field dependence of SABRE at high fields as found earlier has been investigated and attributed to polarization transfer to the substrate by cross-relaxation. The present study provides further evidence for the key role of LACs in the formation of SABRE-derived polarization. Understanding the spin dynamics behind the SABRE method opens the way to optimizing its performance and overcoming the main limitation of NMR, its notoriously low sensitivity.