Wednesday, September 20, 2017

Measuring Nano- to Microstructures from Relayed Dynamic Nuclear Polarization NMR #DNPNMR


Pinon, A.C., et al., Measuring Nano- to Microstructures from Relayed Dynamic Nuclear Polarization NMR. The Journal of Physical Chemistry C, 2017. 121(29): p. 15993-16005.


We show how dynamic nuclear polarization (DNP) NMR can be used in combination with models for polarization dynamics to determine the domain sizes in complex materials. By selectively doping a source component with radicals and leaving the target undoped, we can measure experimental polarization buildup curves which can be compared with simulations based on heterogeneous distributions of polarization within the sample. The variation of the integrated DNP enhancement as a function of the polarization time is found to be characteristic of the geometry. We demonstrate the method experimentally on four different systems where we successfully determine domain sizes between 200 and 20 000 nm, specifically in powdered histidine hydrochloride monohydrate, pore lengths of mesoporous silica materials, and two domain sizes in two-component polymer film coatings. Additionally, we find that even in the apparently homogeneous frozen solutions used as polarization sources in most DNP experiments, polarization is relayed from protons near the radicals to the bulk of the solution by spin diffusion, which explains the experimentally observed buildup times in these samples.

Monday, September 18, 2017

Unprecedented Carbon Signal Enhancement in Liquid-State NMR Spectroscopy #DNPNMR


Pinter, G. and H. Schwalbe, Unprecedented Carbon Signal Enhancement in Liquid-State NMR Spectroscopy. Angew Chem Int Ed Engl, 2017. 56(29): p. 8332-8334.


We shall overcome: As a result of efforts to overcome the sensitivity challenge of liquid-state NMR spectroscopy, a thousand-fold signal enhancement was achieved by dynamic nuclear polarization (DNP) for 13 C signals at high magnetic field (3.4 T) and room temperature, thereby exceeding the predicted limitations of high-field liquid-state in situ DNP.

Friday, September 15, 2017


Barskiy, D.A., et al., NMR Hyperpolarization Techniques of Gases. Chemistry, 2017. 23(4): p. 725-751.


Nuclear spin polarization can be significantly increased through the process of hyperpolarization, leading to an increase in the sensitivity of nuclear magnetic resonance (NMR) experiments by 4-8 orders of magnitude. Hyperpolarized gases, unlike liquids and solids, can often be readily separated and purified from the compounds used to mediate the hyperpolarization processes. These pure hyperpolarized gases enabled many novel MRI applications including the visualization of void spaces, imaging of lung function, and remote detection. Additionally, hyperpolarized gases can be dissolved in liquids and can be used as sensitive molecular probes and reporters. This Minireview covers the fundamentals of the preparation of hyperpolarized gases and focuses on selected applications of interest to biomedicine and materials science.

Thursday, September 14, 2017

[NMR] Nobel Prize winner Nico Bloembergen passed away at age 97


From the Ampere Magnetic Resonance List:

Dear colleagues,

Last week, Nobel laureate Professor Nicolaas Bloembergen, a pioneer in the field of NMR and laser spectroscopy passed away at age of 97. As an undergraduate Bloembergen studied Physics at Utrecht University from 1938 to 1943 and received his PhD in Physics from Leiden University with C.J. Gorter in 1948 on the topic of Nuclear Magnetic Relaxation. His thesis resulted in the famous BPP (Bloembergen, Purcell and Pound) paper which still serves as a point of departure for understanding many NMR relaxation experiments. In 1973 he returned to Leiden and occupied the Lorentz Chair in Physics. In 1981, he was awarded the Nobel Prize in Physics for his work in coherent optics. In 2001 in honour of his achievements, the NMR group at Utrecht University named their laboratory the Bloembergen Building.

For further information on a true scientific giant, please look out for an obituary written by C. Luchinat, R. Boelens, and R. Kaptein that will appear on the Ampere website and in the Ampere newsletter soon.

Also, please see, for example:

Best wishes,
Marc Baldus



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Wednesday, September 13, 2017

Single-scan 13C diffusion-ordered NMR spectroscopy of DNP-hyperpolarised substrates #DNPNMR


Guduff, L., et al., Single-scan 13C diffusion-ordered NMR spectroscopy of DNP-hyperpolarised substrates. Chemistry, 2017: p. n/a-n/a.


Diffusion-ordered NMR spectroscopy (DOSY) is a powerful approach for the analysis of molecular mixtures, yet its application range is limited by the relatively low sensitivity of NMR. We show here that spectrally resolved 13C DOSY data can be collected, in a single scan, for substrates hyperpolarised by dissolution dynamic nuclear polarisation (D-DNP), which provides signal enhancements of several orders of magnitude. For this we use a convection-compensation pulse scheme, which we also analyse by numerical simulation. The proposed method further allows the acquisition of several consecutive DOSY spectra in a single D-DNP experiment.

Monday, September 11, 2017

Overhauser-enhanced magnetic resonance elastography


Salameh, N., et al., Overhauser-enhanced magnetic resonance elastography. NMR in Biomedicine, 2016. 29(5): p. 607-613.


Magnetic resonance elastography (MRE) is a powerful technique to assess the mechanical properties of living tissue. However, it suffers from reduced sensitivity in regions with short T2 and T2* such as in tissue with high concentrations of paramagnetic iron, or in regions surrounding implanted devices. In this work, we exploit the longer T2* attainable at ultra-low magnetic fields in combination with Overhauser dynamic nuclear polarization (DNP) to enable rapid MRE at 0.0065 T. A 3D balanced steady-state free precession based MRE sequence with undersampling and fractional encoding was implemented on a 0.0065 T MRI scanner. A custom-built RF coil for DNP and a programmable vibration system for elastography were developed. Displacement fields and stiffness maps were reconstructed from data recorded in a polyvinyl alcohol gel phantom loaded with stable nitroxide radicals. A DNP enhancement of 25 was achieved during the MRE sequence, allowing the acquisition of 3D Overhauser-enhanced MRE (OMRE) images with (1.5 × 2.7 × 9) mm3 resolution over eight temporal steps and 11 slices in 6 minutes. In conclusion, OMRE at ultra-low magnetic field can be used to detect mechanical waves over short acquisition times. This new modality shows promise to broaden the scope of conventional MRE applications, and may extend the utility of low-cost, portable MRI systems to detect elasticity changes in patients with implanted devices or iron overload. Copyright © 2016 John Wiley & Sons, Ltd.

[NMR] Faculty position at New York University

From the Ampere Magnetic Resonance List



Dear Colleagues,

The Department of Chemistry at New York University is soliciting applications for faculty positions in Chemistry. One of the emphasis areas is biophysical chemistry, which may include NMR or EPR. The deadline for the application is Sep 29, 2017. The full search advertisement is copied and pasted below, and can also be found via the link: http://as.nyu.edu/chemistry/recruitment.html


best wishes,
Nate


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ASSISTANT PROFESSOR

Department of Chemistry
Arts and Science
New York University

The Department of Chemistry at New York University (NYU) invites applications for several tenure-track faculty positions in all areas of Chemistry and Biochemistry, subject to final administrative approval. Successful candidates must have a Ph.D in chemistry or related field and demonstrate the potential to do pioneering research and to teach effectively at the undergraduate and graduate levels. The positions are anticipated to be at the junior level, although exceptional senior level candidates will be considered. The Department of Chemistry is continuing a significant growth plan, including the creation of the Biomedical Chemistry Institute, the Molecular Design Institute, and the addition of numerous senior and junior faculty members. Interested faculty are able to participate in significant interdisciplinary programs within the Washington Square campus, as well as with NYU’s engineering and medical schools, and scholarly activities at its campuses in Shanghai and Abu Dhabi.

Candidates should submit a curriculum vitae, a detailed description of research plans and interests, and a statement of teaching experience and interests. The application should include three letters of recommendation. Review of complete applications will begin September 29, 2017. The anticipated start date is September 1, 2018. Please submit applications through our web portal using the following link: apply.interfolio.com/43972

The Faculty of Arts and Science at NYU is at the heart of a leading research university that spans the globe. We seek scholars of the highest caliber, who embody the diversity of the United States as well as the global society in which we live. We strongly encourage applications from women, racial and ethnic minorities, and other individuals who are under-represented in the profession, across color, creed, race, ethnic and national origin, physical ability, gender and sexual identity, or any other legally protected basis. NYU affirms the value of differing perspectives on the world as we strive to build the strongest possible university with the widest reach. To learn more about the FAS commitment to diversity, equality and inclusion, please read here.

EOE/Affirmative Action/Minorities/Females/Vet/Disabled/Sexual Orientation/Gender Identity

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Nate Traaseth | Associate Professor of Chemistry, NYU | traaseth@nyu.edu | 212-992-9784

lab website | full contact info


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