Monday, November 24, 2014

[NMR] Postdoctoral position in Hyperpolarized Magnetic Resonance at the MR-Centre, Aarhus University Hospital, Denmark

From the Ampere Magnetic Resonance List

Background for the position

The current one year position (with possibility of prolongation) is available through a grant for the LIFE-DNP program obtained from The Danish Council for Strategic Research to the MR Research Centre, Aarhus University and its partners. 


Read more about the MR Research Centre and the program at mr.au.dk

We offer: 

An interdisciplinary and dynamic environment within an international research group. An excellent laboratory infrastructure with state-of-the-art equipment, including one SPINlab polarizer system linked to a 3T clinical scanner and a 9.4T pre-clinical scanner. Additionally, laboratory for cell culture studies, animal based studies and other facilities for patient and clinical scanners are available. 

Project description: 

Hyperpolarized MR is a new technology enhancing MR spectroscopy and imaging for metabolic studies with until now unseen sensitivity. The overall aim of the present research program is to explore metabolic mechanisms that link dietary patterns and lifestyle with diseases included in the metabolic syndrome complex like diabetes, obesity, cancer or heart diseases. The research is based on cells (bio-reactors), animals (rodents and pigs) and further translation to human studies will be initiated soon. 

The holder of the announced Post Doc position is expected to formulate own research based on the hyperpolarization technique. 

Furthermore the researcher should: 

• introduce new bio-probes (spin physics, chemistry etc.) for experimental studies of the metabolic complex diseases; 
• develop novel methods for MR data acquisitions and analysis; 
• interpretation of MR-hyperpolarization data for quantification of metabolic flux patterns relevant for the above general aims and translate these into a clinical perspective. 

Selection criteria 

• The candidate must hold a PhD or equivalent degree in areas linking natural sciences and life sciences. 
• The candidate must demonstrate strong competences in physics, chemistry, data processing, MR-spectroscopy and its application in life-sciences. 
• Prior practical experience with the MR-hyperpolarization technique will be appreciated. 
• Convincing knowledge in proper experimental planning, power calculations, and statistical evaluation of experimental data. 
• An analytical attitude of devising innovative scientific or technical solutions. 
• Excellent scientific track record 
• Excellent English communication skills, both written and verbal 
• An enthusiastic, dedicated and collaborative attitude to the project is prerequisite. 

Relationships 
• The candidate will be employed at the MR Research Centre, Department of Clinical Medicine. The holder of the position will primarily report to the principle investigator Prof. Hans Stødkilde-Jørgensen. 
• The holder of the position is expected to interact with staff at all levels, both internally and externally, regarding relevant research topics. 
• Highly motivated and ambitious candidates are encouraged to apply. Solid experience and an excellent track record gained in leading laboratories in the research field will be considered a distinct advantage. In all cases, ability to perform the job will be the primary consideration, and thus we encourage all – regardless of their personal background and status – to apply. 

Questions 
Further information can be requested from prof. Hans Stødkilde-Jørgensen (+45 7845 6113), assistant prof. Christoffer Laustsen (+45 7846 6139) or associate prof. Steffen Ringgaard (+45 7845 6123). 

For more information on working at Aarhus University and living in Denmark: http://ias.au.dk/international-academic-staff-ias/

Aarhus University is an academically diverse and strongly research-oriented institution that creates and shares knowledge. The university was founded in 1928 and today it has several world class research fields. Aarhus University (AU) is a top ten university among universities founded within the past 100 years. It has a long tradition of partnerships with some of the world's best research institutions and university networks. Please read more about Aarhus University at http://www.au.dk/en/about/profile

Application formalities 
The application must be in English and include a curriculum vitae, degree certificate, a complete list of publications, a statement of future research plans and information about research activities, teaching portfolio and verified information on previous teaching experience (if any).

Application deadline: 
All applications must be made online and received by: 17.12.2014 

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C&EN: Agilent Draws Academics’ Ire

C&EN, the magazine of the American Chemical Society had an interesting article about Agilent leaving the NMR business, that you can find here:


Also, if you wanna read the open letter of the NMR community to Agilent, you can find it here:

Direct Evidence of Imino Acid–Aromatic Interactions in Native Collagen Protein by DNP-Enhanced Solid-State NMR Spectroscopy


Singh, C., et al., Direct Evidence of Imino Acid–Aromatic Interactions in Native Collagen Protein by DNP-Enhanced Solid-State NMR Spectroscopy. The Journal of Physical Chemistry Letters, 2014. 5(22): p. 4044-4048.


Aromatic amino acids (AAAs) have rare presence (?1.4% abundance of Phe) inside of collagen protein, which is the most abundant animal protein playing a functional role in skin, bone, and connective tissues. The role of AAAs is very crucial and has been debated. We present here experimental results depicting interaction of AAAs with imino acids in a native collagen protein sample. The interaction is probed by solid-state NMR (ssNMR) spectroscopy experiments such as 1H?13C heteronuclear correlation (HETCOR) performed on a native collagen sample. The natural abundance 13C spectrum was obtained by dynamic nuclear polarization (DNP) sensitivity enhancement coupled with ssNMR, providing 30-fold signal enhancement. Our results also open up new avenues of probing collagen structure/dynamics closest to the native state by ssNMR experiments coupled with DNP.

Friday, November 21, 2014

Unraveling the core-shell structure of ligand-capped Sn/SnOx nanoparticles by surface-enhanced nuclear magnetic resonance, Mossbauer, and X-ray absorption spectroscopies


Protesescu, L., et al., Unraveling the core-shell structure of ligand-capped Sn/SnOx nanoparticles by surface-enhanced nuclear magnetic resonance, Mossbauer, and X-ray absorption spectroscopies. ACS Nano, 2014. 8(3): p. 2639-48.


A particularly difficult challenge in the chemistry of nanomaterials is the detailed structural and chemical analysis of multicomponent nano-objects. This is especially true for the determination of spatially resolved information. In this study, we demonstrate that dynamic nuclear polarization surface-enhanced solid-state NMR spectroscopy (DNP-SENS), which provides selective and enhanced NMR signal collection from the (near) surface regions of a sample, can be used to resolve the core-shell structure of a nanoparticle. Li-ion anode materials, monodisperse 10-20 nm large tin nanoparticles covered with a approximately 3 nm thick layer of native oxides, were used in this case study. DNP-SENS selectively enhanced the weak 119Sn NMR signal of the amorphous surface SnO2 layer. Mossbauer and X-ray absorption spectroscopies identified a subsurface SnO phase and quantified the atomic fractions of both oxides. Finally, temperature-dependent X-ray diffraction measurements were used to probe the metallic beta-Sn core and indicated that even after 8 months of storage at 255 K there are no signs of conversion of the metallic beta-Sn core into a brittle semiconducting alpha-phase, a phase transition which normally occurs in bulk tin at 286 K (13 degrees C). Taken together, these results indicate that Sn/SnOx nanoparticles have core/shell1/shell2 structure of Sn/SnO/SnO2 phases. The study suggests that DNP-SENS experiments can be carried on many types of uniform colloidal nanomaterials containing NMR-active nuclei, in the presence of either hydrophilic (ion-capped surfaces) or hydrophobic (capping ligands with long hydrocarbon chains) surface functionalities.

Wednesday, November 19, 2014

NMR-based structural biology enhanced by dynamic nuclear polarization at high magnetic field


Koers, E.J., et al., NMR-based structural biology enhanced by dynamic nuclear polarization at high magnetic field. J Biomol NMR, 2014. 60(2-3): p. 157-68.


Dynamic nuclear polarization (DNP) has become a powerful method to enhance spectroscopic sensitivity in the context of magnetic resonance imaging and nuclear magnetic resonance spectroscopy. We show that, compared to DNP at lower field (400 MHz/263 GHz), high field DNP (800 MHz/527 GHz) can significantly enhance spectral resolution and allows exploitation of the paramagnetic relaxation properties of DNP polarizing agents as direct structural probes under magic angle spinning conditions. Applied to a membrane-embedded K(+) channel, this approach allowed us to refine the membrane-embedded channel structure and revealed conformational substates that are present during two different stages of the channel gating cycle. High-field DNP thus offers atomic insight into the role of molecular plasticity during the course of biomolecular function in a complex cellular environment.

Monday, November 17, 2014

Dynamic nuclear polarization and Hanle effect in (In,Ga)As/GaAs quantum dots. Role of nuclear spin fluctuations


Gerlovin, I.Y., et al., Dynamic nuclear polarization and Hanle effect in (In,Ga)As/GaAs quantum dots. Role of nuclear spin fluctuations. AIP Conference Proceedings, 2013. 1566(1): p. 319-320.


The degree of circular polarization of photoluminescence of (In,Ga)As quantum dots as a function of magnetic field applied perpendicular to the optical axis (Hanle effect) is experimentally studied. The measurements have been performed at various regimes of the optical excitation modulation. The analysis of experimental data has been performed in the framework of a vector model of regular nuclear spin polarization and its fluctuations. The analysis allowed us to evaluate the magnitude of nuclear polarization and its dynamics at the experimental conditions used.

Friday, November 14, 2014

The electron depolarization during dynamic nuclear polarization: measurements and simulations


Hovav, Y., et al., The electron depolarization during dynamic nuclear polarization: measurements and simulations. Phys. Chem. Chem. Phys., 2014.


Dynamic nuclear polarization is typically explained either using microscopic systems, such as in the solid effect and cross effect mechanisms, or using the macroscopic formalism of spin temperature which assumes that the state of the electrons can be described using temperature coefficients, giving rise to the thermal mixing mechanism. The distinction between these mechanisms is typically made by measuring the DNP spectrum - i.e. the nuclear enhancement profile as a function of irradiation frequency. In particular, we have previously used the solid effect and cross effect mechanisms to explain temperature dependent DNP spectra. Our past analysis has however neglected the effect of depolarization of the electrons resulting from the microwave (MW) irradiation. In this work we concentrate on this electron depolarization process and perform electron-electron double resonance (ELDOR) experiments on TEMPOL and trityl frozen solutions, using a 3.34 Tesla magnet and at 2.7-30 K, in order to measure the state of the electron polarization during DNP. The experiments indicate that a significant part of the EPR line is affected by the irradiation due to spectral diffusion. Using a theoretical framework based on rate equations for the polarizations of the different electron spin packets and for those of the nuclei we simulated the various ELDOR line-shapes and reproduced the MW frequency and irradiation time dependence. The obtained electron polarization distribution cannot be described using temperature coefficients as required by the classical thermal mixing mechanism, and therefore the DNP mechanism cannot be described by thermal mixing. Instead, the theoretical framework presented here for the analysis of the ELDOR data forms a basis for future interpretation of DNP spectra in combination with EPR measurements.

Wednesday, November 12, 2014

DNP visiting scientist positio at NHMFL

From the Ampere Magnetic Resonance List

A visiting scientist position is available at the U.S. National High Magnetic Field Laboratory (NHMFL) in Tallahassee Florida as part of a major initiative on Dynamic Nuclear Polarization (DNP) including magic-angle spinning (MAS) DNP, dissolution DNP and Overhauser solution DNP. The position will be focused primarily on but not limited to MAS DNP. A Bruker 600MHz DNP system has recently been installed and a 600MHz field-sweepable wide-bore magnet will be delivered soon to the NHMFL. The visiting scientist is expected to develop independent and collaborative research in chemical, biological and material applications of DNP as well as DNP instrumentation and technology. The scientist will work within a team of faculty and engineers through the NMR, EMR and AMRIS programs and in collaboration with users of the NHMFL facilities. 

Minimum qualifications include a Ph.D. in Chemistry, Physics, Biology or a related discipline. Experience in DNP is expected. To apply, please send a CV, a cover letter describing your experience and research interests, and contact information for three references to 

Zhehong Gan 
National High Magnetic Field Laboratory 
1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA 

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Hybrid polarizing solids for pure hyperpolarized liquids through dissolution dynamic nuclear polarization


Gajan, D., et al., Hybrid polarizing solids for pure hyperpolarized liquids through dissolution dynamic nuclear polarization. Proc. Nat. Aca. Sci. USA, 2014. 111(41): p. 14693-14697.


Hyperpolarization of substrates for magnetic resonance spectroscopy (MRS) and imaging (MRI) by dissolution dynamic nuclear polarization (D-DNP) usually involves saturating the ESR transitions of polarizing agents (PAs; e.g., persistent radicals embedded in frozen glassy matrices). This approach has shown enormous potential to achieve greatly enhanced nuclear spin polarization, but the presence of PAs and/or glassing agents in the sample after dissolution can raise concerns for in vivo MRI applications, such as perturbing molecular interactions, and may induce the erosion of hyperpolarization in spectroscopy and MRI. We show that D-DNP can be performed efficiently with hybrid polarizing solids (HYPSOs) with 2,2,6,6-tetramethyl-piperidine-1-oxyl radicals incorporated in a mesostructured silica material and homogeneously distributed along its pore channels. The powder is wetted with a solution containing molecules of interest (for example, metabolites for MRS or MRI) to fill the pore channels (incipient wetness impregnation), and DNP is performed at low temperatures in a very efficient manner. This approach allows high polarization without the need for glass-forming agents and is applicable to a broad range of substrates, including peptides and metabolites. During dissolution, HYPSO is physically retained by simple filtration in the cryostat of the DNP polarizer, and a pure hyperpolarized solution is collected within a few seconds. The resulting solution contains the pure substrate, is free from any paramagnetic or other pollutants, and is ready for in vivo infusion.

Monday, November 10, 2014

Amplifying dynamic nuclear polarization of frozen solutions by incorporating dielectric particles


Kubicki, D.J., et al., Amplifying dynamic nuclear polarization of frozen solutions by incorporating dielectric particles. J Am Chem Soc, 2014. 136(44): p. 15711-8.


There is currently great interest in understanding the limits on NMR signal enhancements provided by dynamic nuclear polarization (DNP), and in particular if the theoretical maximum enhancements can be achieved. We show that over a 2-fold improvement in cross-effect DNP enhancements can be achieved in MAS experiments on frozen solutions by simply incorporating solid particles into the sample. At 9.4 T and approximately 105 K, enhancements up to epsilonH = 515 are obtained in this way, corresponding to 78% of the theoretical maximum. We also underline that degassing of the sample is important to achieve highest enhancements. We link the amplification effect to the dielectric properties of the solid material, which probably gives rise to scattering, diffraction, and amplification of the microwave field in the sample. This is substantiated by simulations of microwave propagation. A reduction in sample heating at a given microwave power also likely occurs due to reduced dielectric loss. Simulations indicate that the microwave field (and thus the DNP enhancement) is inhomogeneous in the sample, and we deduce that in these experiments between 5 and 10% of the solution actually yields the theoretical maximum signal enhancement of 658. The effect is demonstrated for a variety of particles added to both aqueous and organic biradical solutions.

Friday, November 7, 2014

LIGHT-SABRE enables efficient in-magnet catalytic hyperpolarization


Theis, T., et al., LIGHT-SABRE enables efficient in-magnet catalytic hyperpolarization. J Magn Reson, 2014. 248C(0): p. 23-26.


Nuclear spin hyperpolarization overcomes the sensitivity limitations of traditional NMR and MRI, but the most general method demonstrated to date (dynamic nuclear polarization) has significant limitations in scalability, cost, and complex apparatus design. As an alternative, signal amplification by reversible exchange (SABRE) of parahydrogen on transition metal catalysts can hyperpolarize a variety of substrates, but to date this scheme has required transfer of the sample to low magnetic field or very strong RF irradiation. Here we demonstrate "Low-Irradiation Generation of High Tesla-SABRE" (LIGHT-SABRE) which works with simple pulse sequences and low power deposition; it should be usable at any magnetic field and for hyperpolarization of many different nuclei. This approach could drastically reduce the cost and complexity of producing hyperpolarized molecules.

Wednesday, November 5, 2014

Cross polarization from (1)H to quadrupolar (6)Li nuclei for dissolution DNP


Perez Linde, A.J., et al., Cross polarization from (1)H to quadrupolar (6)Li nuclei for dissolution DNP. Phys Chem Chem Phys, 2014. 16(45): p. 24813-7.


Cross polarization from protons to quadrupolar (6)Li nuclei is combined with dynamic nuclear polarization of protons at 1.2 K and 6.7 T using TEMPOL as a polarizing agent followed by rapid dissolution. Compared to direct (6)Li DNP without cross-polarization, a higher nuclear spin polarization P((6)Li) can be obtained in a shorter time. A double resonance (1)H-(6)Li probe was designed that is equipped for Longitudinally Detected Electron Spin Resonance.

Tuesday, November 4, 2014

[NMR] Postdoctoral Position: Development of Biological Pulsed High-Field EPR Applications

From the Ampere Magnetic Resonance mailing list:

Location: National High Magnetic Field Laboratory, Tallahassee, FL
Start Date: Fall 2014 or early 2015

A postdoctoral position is available in the Electron Magnetic Resonance (EMR) group at the U.S. National High Magnetic Field Laboratory (NHMFL). The position will be focused on the development of biological applications utilizing a recently acquired state-of-the-art pulsed high-frequency (W-band, or 94 GHz) EPR spectrometer (HiPER). The HiPER instrument provides kilowatt powers, enabling nanosecond p/2 pulses. Furthermore, its quasi-optical design gives exceptional cross-polar isolation, enabling induction-mode detection while excitation pulses are incident on the sample. Thus, HiPER offers true nanosecond time resolution and the possibility to perform fourier-transform-type high-field EPR measurements, akin to what is routinely achieved in NMR. HiPER also offers exceptional sensitivity. As such, it is expected to have a major impact on both the materials and biological applications programs at the NHMFL in the coming years. The EMR facility additionally boasts a wide range of other unique pulsed and continuous wave high-field EPR instruments spanning the range from 9 GHz to 2.5 THz, and magnetic fields up to 45 T. The group in Tallahassee comprises five faculty-level researchers, as well as a large cohort of graduate students and postdocs. The group also has strong interactions with EPR groups in chemistry and biology at both Florida State University and the University of Florida in Gainesville. Further information concerning the NHMFL EMR group, including links to recent publications, can be found at: http://magnet.fsu.edu/usershub/scientificdivisions/emr/index.html

Minimum qualifications include a Ph.D. in Chemistry, Physics, Biology or a related discipline. Experience in one or more of the following areas is preferred, but not essential: EPR spectroscopy, particularly pulsed and/or high-field EPR; instrument design/development; biological EPR applications. Questions regarding the position should be directed to the EMR Director, Stephen Hill (shill@magnet.fsu.edu). To apply, please send a CV, a cover letter describing your experience and research interests, and the contact information for three references, preferably by email to:

Stephen Hill
National High Magnetic Field Laboratory
1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA

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Monday, November 3, 2014

Evaluation of Activation Energies for Pairwise and Non-Pairwise Hydrogen Addition to Propyne Over Pd/Aluminosilicate Fiberglass Catalyst by Parahydrogen-Induced Polarization (PHIP)


Salnikov, O.G., et al., Evaluation of Activation Energies for Pairwise and Non-Pairwise Hydrogen Addition to Propyne Over Pd/Aluminosilicate Fiberglass Catalyst by Parahydrogen-Induced Polarization (PHIP). Appl. Magn. Reson., 2014. 45(10): p. 1051-1061.


Hydrogenation of propyne to propene over Pd/aluminosilicate fiberglass catalyst in the temperature range 175–350 °C was investigated with the use of parahydrogen-induced polarization (PHIP) technique. Activation energies for both pairwise and non-pairwise H2 addition routes were estimated. It was found that at 175–275 °C the activation energies for hydrogen addition to the triple bond of propyne have similar values (about 60–70 kJ/mol) for both routes of hydrogen addition. At higher temperatures (275–350 °C), the rate constant for pairwise hydrogen addition reaches a maximum value while the rate constant for non-pairwise hydrogen addition continues to increase with increasing temperature.