keyword
MENU ▼
Read by QxMD icon Read
search

Dynamic nuclear polarization

keyword
https://www.readbyqxmd.com/read/28933161/identifying-the-structural-basis-for-the-increased-stability-of-the-solid-electrolyte-interphase-formed-on-silicon-with-the-additive-fluoroethylene-carbonate
#1
Yanting Jin, Nis-Julian H Kneusels, Pieter C M M Magusin, Gunwoo Kim, Elizabeth Castillo-Martinez, Lauren E Marbella, Rachel N Kerber, Duncan J Howe, Subhradip Paul, Tao Liu, Clare P Grey
To elucidate the role of fluoroethylene carbonate (FEC) as an additive in the standard carbonate-based electrolyte for Li-ion batteries, the solid electrolyte interphase (SEI) formed during electrochemical cycling on silicon anodes was analyzed with a combination of solution and solid-state NMR techniques, including dynamic nuclear polarization. To facilitate characterization via 1D and 2D NMR, we synthesized (13)C-enriched FEC, ultimately allowing a detailed structural assignment of the organic SEI. We find that the soluble PEO-like linear oligomeric electrolyte breakdown products that are observed after cycling in the standard ethylene carbonate (EC)-based electrolyte are suppressed in the presence of 10 vol % FEC additive...
September 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28930998/in-vitro-ovule-cultivation-for-live-cell-imaging-of-zygote-polarization-and-embryo-patterning-in-arabidopsis-thaliana
#2
Daisuke Kurihara, Yusuke Kimata, Tetsuya Higashiyama, Minako Ueda
In most flowering plants, the zygote and embryo are hidden deep in the mother tissue, and thus it has long been a mystery of how they develop dynamically; for example, how the zygote polarizes to establish the body axis and how the embryo specifies various cell fates during organ formation. This manuscript describes an in vitro ovule culture method to perform live-cell imaging of developing zygotes and embryos of Arabidopsis thaliana. The optimized cultivation medium allows zygotes or early embryos to grow into fertile plants...
September 11, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28888182/instrumentation-for-cryogenic-magic-angle-spinning-dynamic-nuclear-polarization-using-90l-of-liquid-nitrogen-per-day
#3
Brice J Albert, Seong Ho Pahng, Nicholas Alaniva, Erika L Sesti, Peter W Rand, Edward P Saliba, Faith J Scott, Eric J Choi, Alexander B Barnes
Cryogenic sample temperatures can enhance NMR sensitivity by extending spin relaxation times to improve dynamic nuclear polarization (DNP) and by increasing Boltzmann spin polarization. We have developed an efficient heat exchanger with a liquid nitrogen consumption rate of only 90L per day to perform magic-angle spinning (MAS) DNP experiments below 85K. In this heat exchanger implementation, cold exhaust gas from the NMR probe is returned to the outer portion of a counterflow coil within an intermediate cooling stage to improve cooling efficiency of the spinning and variable temperature gases...
September 1, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28887303/dynamic-nuclear-polarization-facilitates-monitoring-of-pyruvate-metabolism-in-trypanosoma-brucei
#4
You Zhuo, Ciro D Cordeiro, S Khan Hekmatyar, Roberto Docampo, James H Prestegard
Dynamic nuclear polarization (DNP) provides sensitivity improvements that make NMR a viable method for following metabolic conversions in real time. There are now many in vivo applications to animal systems and even to diagnosis of human disease. However, application to microbial systems is rare. Here we demonstrate its application to the pathogenic protozoan, Trypanosoma brucei, using hyperpolarized (13)C1- pyruvate as a substrate and compare the parasite metabolism to that of commonly cultured mammalian cell lines, HEK-293 and Hep-G2...
September 8, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28872852/hydroxyapatites-key-structural-questions-and-answers-from-dnp-dynamic-nuclear-polarization
#5
Cesar Leroy, Fabien Aussenac, Laure Bonhomme-Coury, Akiyoshi Osaka, Satoshi Hayakawa, Florence Babonneau, Cristina Coelho Diogo, Christian Bonhomme
We demonstrate that NMR/DNP (Dynamic Nuclear Polarization) allows an unprecedented description of carbonate substituted hydroxyapatite (CHAp). Key structural questions related to order/disorder and clustering of carbonates are tackled by using distance sensitive DNP experiments using (13)C-(13)C recoupling. Such experiments are easily implemented due to huge DNP gain (orders of magnitude). DNP is efficiently mediated by quasi one-dimensional spin diffusion through the hydroxyl columns present in the CHAp structure (thought as "highways" for spin diffusion)...
September 5, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28863546/terahertz-absorption-of-lysozyme-in-solution
#6
Daniel R Martin, Dmitry V Matyushov
Absorption of radiation by solution is described by its frequency-dependent dielectric function and can be viewed as a specific application of the dielectric theory of solutions. For ideal solutions, the dielectric boundary-value problem separates the polar response into the polarization of the void in the liquid, created by the solute, and the response of the solute dipole. In the case of a protein as a solute, protein nuclear dynamics do not project on significant fluctuations of the dipole moment in the terahertz domain of frequencies and the protein dipole can be viewed as dynamically frozen...
August 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28844254/perspectives-on-paramagnetic-nmr-from-a-life-sciences-infrastructure
#7
Enrico Ravera, Giacomo Parigi, Claudio Luchinat
The effects arising in NMR spectroscopy because of the presence of unpaired electrons, collectively referred to as "paramagnetic NMR" have attracted increasing attention over the last decades. From the standpoint of the structural and mechanistic biology, paramagnetic NMR provides long range restraints that can be used to assess the accuracy of crystal structures in solution and to improve them by simultaneous refinements through NMR and X-ray data. These restraints also provide information on structure rearrangements and conformational variability in biomolecular systems...
September 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28839124/biochemical-phosphates-observed-using-hyperpolarized-31-p-in-physiological-aqueous-solutions
#8
Atara Nardi-Schreiber, Ayelet Gamliel, Talia Harris, Gal Sapir, Jacob Sosna, J Moshe Gomori, Rachel Katz-Brull
The dissolution-dynamic nuclear polarization technology had previously enabled nuclear magnetic resonance detection of various nuclei in a hyperpolarized state. Here, we show the hyperpolarization of (31)P nuclei in important biological phosphates (inorganic phosphate and phosphocreatine) in aqueous solutions. The hyperpolarized inorganic phosphate showed an enhancement factor >11,000 (at 5.8 T, 9.3% polarization) in D2O (T1 29.4 s). Deuteration and the solution composition and pH all affected the lifetime of the hyperpolarized state...
August 24, 2017: Nature Communications
https://www.readbyqxmd.com/read/28834782/improved-strategies-for-dnp-enhanced-2d-1-h-x-heteronuclear-correlation-spectroscopy-of-surfaces
#9
Takeshi Kobayashi, Frédéric A Perras, Umesh Chaudhary, Igor I Slowing, Wenyu Huang, Aaron D Sadow, Marek Pruski
We demonstrate that dynamic nuclear polarization (DNP)-enhanced (1)H-X heteronuclear correlation (HETCOR) measurements of hydrogen-rich surface species are better accomplished by using proton-free solvents. This approach notably prevents HETCOR spectra from being obfuscated by the solvent-derived signals otherwise present in DNP measurements. Additionally, in the hydrogen-rich materials studied here, which included functionalized mesoporous silica nanoparticles and metal organic frameworks, the use of proton-free solvents afforded higher sensitivity gains than the commonly used solvents containing protons...
August 12, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28815237/induced-polarization-restricts-the-conformational-distribution-of-a-light-harvesting-molecular-triad-in-the-ground-state
#10
Oleg N Starovoytov, Pengzhi Zhang, Piotr Cieplak, Margaret S Cheung
The light-harvesting molecular triad consisting of carotenoid polyene (C), diaryl-porphyrin (P) and pyrrole-fullerene (C60) is a donor-acceptor molecule capable of absorbing incident light in the visible range. Its ability to convert solar energy to electrical excitation and charge separation energy suggests a great potential in real-world applications. The ensemble of its conformations under ambient conditions varies widely according to its electronic state. In previous work, we applied a non-polarizable model to study the conformational distribution of the molecular triad in the ground and charge separated states...
August 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28762740/in-situ-characterization-of-pharmaceutical-formulations-by-dynamic-nuclear-polarization-enhanced-mas-nmr
#11
Qing Zhe Ni, Fengyuan Yang, Thach V Can, Ivan V Sergeyev, Suzanne M D'Addio, Sudheer K Jawla, Yongjun Li, Maya P Lipert, Wei Xu, R Thomas Williamson, Anthony Leone, Robert G Griffin, Yongchao Su
A principal advantage of magic angle spinning (MAS) NMR spectroscopy lies in its ability to determine molecular structure in a noninvasive and quantitative manner. Accordingly, MAS should be widely applicable to studies of the structure of active pharmaceutical ingredients (API) and formulations. However, the low sensitivity encountered in spectroscopy of natural abundance APIs present at low concentration has limited the success of MAS experiments. Dynamic nuclear polarization (DNP) enhances NMR sensitivity and can be used to circumvent this problem provided that suitable paramagnetic polarizing agent can be incorporated into the system without altering the integrity of solid dosages...
August 31, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28759067/indirect-nmr-detection-of-transient-guanosyl-radical-protonation-in-neutral-aqueous-solution
#12
O B Morozova, N N Fishman, A V Yurkovskaya
By using the time-resolved chemically induced dynamic nuclear polarization technique, we show that the neutral guanosyl radical, G(-H)˙, formed in the reaction of guanosine-5'-monophosphate with a triplet-excited 3,3',4,4'-tetracarboxy benzophenone in neutral aqueous solution, protonates readily at the N7 position with the formation of a new guanosyl cation radical (G˙(+))'.
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28746728/analysis-of-the-electronic-structure-of-the-special-pair-of-a-bacterial-photosynthetic-reaction-center-by-13-c-photochemically-induced-dynamic-nuclear-polarization-magic-angle-spinning-nmr-using-a-double-quantum-axis
#13
Marija Najdanova, Daniel Gräsing, A Alia, Jörg Matysik
The origin of the functional symmetry break in bacterial photosynthesis challenges since several decades. Although structurally very similar, the two branches of cofactors in the reaction center (RC) protein complex act very differently. Upon photochemical excitation, an electron is transported along one branch, while the other remains inactive. Photochemically induced dynamic nuclear polarization (photo-CIDNP) magic-angle spinning (MAS) (13) C NMR revealed that the two bacteriochlorophyll cofactors forming the "Special Pair" donor dimer are already well distinguished in the electronic ground-state...
July 26, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28745884/origins-of-small-proton-chemical-shift-differences-in-monodeuterated-methyl-groups
#14
O Maduka Ogba, Stuart J Elliott, David A Kolin, Lynda J Brown, Sebastian Cevallos, Stuart Sawyer, Malcolm H Levitt, Daniel J O'Leary
We have recently shown that the small proton chemical shift difference in 2-methyl-1-(methyl-d)piperidine supports a long-lived nuclear spin state. To identify additional candidate molecules with CH2D groups exhibiting accessible long-lived states, and to investigate the factors governing the magnitude of the shift differences, we report a computational and experimental investigation of methyl rotational equilibria and proton chemical shifts in a variety of 2-substituted 1-(methyl-d)piperidines. The polarity and size of the 2-substituent affect the 1,2-stereoisomeric relationship, and consequently, the strength of the rotational asymmetry within the CH2D group...
August 17, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28742127/tpc1-is-an-important-zn-ii-2cys6-transcriptional-regulator-required-for-polarized-growth-and-virulence-in-the-rice-blast-fungus
#15
Rita Galhano, Adriana Illana, Lauren S Ryder, Julio Rodríguez-Romero, Marie Demuez, Muhammad Badaruddin, Ana Lilia Martinez-Rocha, Darren M Soanes, David J Studholme, Nicholas J Talbot, Ane Sesma
The establishment of polarity is a critical process in pathogenic fungi, mediating infection-related morphogenesis and host tissue invasion. Here, we report the identification of TPC1 (Transcription factor for Polarity Control 1), which regulates invasive polarized growth in the rice blast fungus Magnaporthe oryzae. TPC1 encodes a putative transcription factor of the fungal Zn(II)2Cys6 family, exclusive to filamentous fungi. Tpc1-deficient mutants show severe defects in conidiogenesis, infection-associated autophagy, glycogen and lipid metabolism, and plant tissue colonisation...
July 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28714674/characterization-of-chemical-exchange-using-relaxation-dispersion-of-hyperpolarized-nuclear-spins
#16
Mengxiao Liu, Yaewon Kim, Christian Hilty
Chemical exchange phenomena are ubiquitous in macromolecules, which undergo conformational change or ligand complexation. NMR relaxation dispersion (RD) spectroscopy based on a Carr-Purcell-Meiboom-Gill pulse sequence is widely applied to identify the exchange and measure the lifetime of intermediate states on the millisecond time scale. Advances in hyperpolarization methods improve the applicability of NMR spectroscopy when rapid acquisitions or low concentrations are required, through an increase in signal strength by several orders of magnitude...
September 5, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28712722/cell-polarity-regulates-biased-myosin-activity-and-dynamics-during-asymmetric-cell-division-via-drosophila-rho-kinase-and-protein-kinase-n
#17
Anna Tsankova, Tri Thanh Pham, David Salvador Garcia, Fabian Otte, Clemens Cabernard
Cell and tissue morphogenesis depends on the correct regulation of non-muscle Myosin II, but how this motor protein is spatiotemporally controlled is incompletely understood. Here, we show that in asymmetrically dividing Drosophila neural stem cells, cell intrinsic polarity cues provide spatial and temporal information to regulate biased Myosin activity. Using live cell imaging and a genetically encoded Myosin activity sensor, we found that Drosophila Rho kinase (Rok) enriches for activated Myosin on the neuroblast cortex prior to nuclear envelope breakdown (NEB)...
July 24, 2017: Developmental Cell
https://www.readbyqxmd.com/read/28711061/relation-between-cidnp-formed-upon-geminate-and-bulk-recombination-of-radical-pairs
#18
Denis V Sosnovsky, Olga B Morozova, Alexandra V Yurkovskaya, Konstantin L Ivanov
A theoretical approach to time-resolved Chemically Induced Dynamic Nuclear Polarization (CIDNP) is proposed, which allows one to obtain the general relation between polarization formed upon recombination of geminate spin-correlated radical pairs, the so-called G-pairs, and upon recombination of radical pairs formed by encounters of free radicals in solution, the so-called F-pairs. This relation is described by a universal parameter denoted as γ. In this work, the γ value is computed for the arbitrary spin multiplicity, singlet or triplet, of the precursor of the G-pairs as well as for arbitrary recombination rate constants of radical pairs in singlet and triplet states, kS and kT, respectively...
July 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28709996/applications-of-solid-state-nmr-to-membrane-proteins
#19
REVIEW
Vladimir Ladizhansky
Membrane proteins mediate flow of molecules, signals, and energy between cells and intracellular compartments. Understanding membrane protein function requires a detailed understanding of the structural and dynamic properties involved. Lipid bilayers provide a native-like environment for structure-function investigations of membrane proteins. In this review we give a general discourse on the recent progress in the field of solid-state NMR of membrane proteins. Solid-state NMR is a variation of NMR spectroscopy that is applicable to molecular systems with restricted mobility, such as high molecular weight proteins and protein complexes, supramolecular assemblies, or membrane proteins in a phospholipid environment...
July 11, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28708395/dynamic-nuclear-polarization-of-long-lived-nuclear-spin-states-in-methyl-groups
#20
Jean-Nicolas Dumez, Basile Vuichoud, Daniele Mammoli, Aurélien Bornet, Arthur C Pinon, Gabriele Stevanato, Benno Meier, Geoffrey Bodenhausen, Sami Jannin, Malcolm H Levitt
We have induced hyperpolarized long-lived states in compounds containing (13)C-bearing methyl groups by dynamic nuclear polarization (DNP) at cryogenic temperatures, followed by dissolution with a warm solvent. The hyperpolarized methyl long-lived states give rise to enhanced antiphase (13)C NMR signals in solution, which often persist for times much longer than the (13)C and (1)H spin-lattice relaxation times under the same conditions. The DNP-induced effects are similar to quantum-rotor-induced polarization (QRIP) but are observed in a wider range of compounds because they do not depend critically on the height of the rotational barrier...
July 19, 2017: Journal of Physical Chemistry Letters
keyword
keyword
84092
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"