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Solid state NMR

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https://www.readbyqxmd.com/read/28448441/characterization-of-compounds-with-tumor-cell-proliferation-inhibition-activity-from-mushroom-phellinus-baumii-mycelia-produced-by-solid-state-fermentation
#1
Henan Zhang, Qian Shao, Wenhan Wang, Jingsong Zhang, Zhong Zhang, Yanfang Liu, Yan Yang
The inhibition of tumor-cell proliferationbyan organicsolvent extract from the solid-state fermentation of Phellinus baumii mycelia inoculated in rice medium was investigated in vitro. The active compounds inhibiting tumor-cell proliferation were characterized. Results revealed that all (petroleum ether, chloroform, ethyl acetate, and butanol) fractions inhibited tumor-cell proliferation in a dose-dependent fashion. The ethyl acetate extract had the highest inhibitory effecton tumor-cell proliferation, and the butanol fraction had the lowest...
April 27, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28447786/a-3d-mas-nmr-experiment-utilizing-through-space-15n-15n-correlations
#2
Kevin J Donovan, Robert Silvers, Sara Linse, Robert G Griffin
We demonstrate a novel 3D NNC magic angle spinning (MAS) NMR experiment that generates 15N- 15N internuclear contacts in protein systems using an optimized 15N- 15N proton assisted recoupling (PAR) mixing period and a 13C dimension for improved resolution. The optimized PAR condition permits the acquisition of high signal-to-noise 3D data that enables backbone chemical shift assignments using a strategy that is complementary to current schemes. The spectra can also provide distance constraints. The utility of the experiment is demonstrated on an M0Ab1-42 fibril sample that yields high-quality data that is readily assigned and interpreted...
April 27, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28447699/determination-of-paramagnetic-concentrations-inside-a-diamagnetic-matrix-using-solid-state-nmr
#3
Sébastien Maron, Nadège Ollier, Thierry Gacoin, Géraldine Dantelle
The determination of very low doping levels in solid materials is an important issue for many applications. When considering paramagnetic dopants, the NMR relaxation technique appears to be much more accurate than classical techniques such as Vegard's law resulting from X-ray diffraction (XRD) measurements or chemical analysis that cannot provide information on appropriate dopant spatial distributions. In a recent report, the linear variation of 1/T1, i.e. the nuclear relaxation rate, as a function of Nd(3+) content has been used to determine doping levels with a good dispersion homogeneity in the monazite LaPO4 matrix down to 0...
April 27, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28446334/improving-sensitivity-of-solid-state-nmr-spectroscopy-by-rational-design-of-polarizing-agents-for-dynamic-nuclear-polarization
#4
Dominik J Kubicki, Lyndon Emsley
We review our recent efforts to optimize the efficiency of polarizing agents for Dynamic Nuclear Polarization (DNP) in solid-state MAS NMR spectroscopy. We elucidate the links between DNP performance, molecular structure and electronic relaxation properties of dinitroxide biradicals. We show that deuteration and increased bulkiness lead to slower electronic relaxation and in turn to higher DNP enhancements. We also show that the incorporation of solid dielectric particles into the sample is a general method of amplifying DNP enhancements by about a factor of two...
April 26, 2017: Chimia
https://www.readbyqxmd.com/read/28441022/a-low-valent-lead-hydride-and-its-extreme-low-field-1h-nmr-chemical-shift
#5
Julia Schneider, Christian Patrick Sindlinger, Klaus Eichele, Hartmut Schubert, Lars Wesemann
Although hydrides of the group 14 elements are well known as versatile starting materials in many chemical transformations, a hydride of lead in oxidation state II is so far unknown. In this work we finally complete the jigsaw puzzle by reporting the isolation of the first low valent organolead hydride. The thermolabile dimeric organolead hydride was synthesized at low temperature and fea-tures a hydride 1H NMR signal (in solution 35.61 ppm; in the solid state 31.1 ppm) at the lowest field observed so far for a diamagnetic compound in agreement with quantum chemical predictions...
April 25, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28438365/protein-conformational-dynamics-studied-by-15-n-and-1-h-r1%C3%AF-relaxation-dispersion-application-to-wild-type-and-g53a-ubiquitin-crystals
#6
Diego F Gauto, Audrey Hessel, Petra Rovó, Vilius Kurauskas, Rasmus Linser, Paul Schanda
Solid-state NMR spectroscopy can provide site-resolved information about protein dynamics over many time scales. Here we combine protein deuteration, fast magic-angle spinning (~45-60kHz) and proton detection to study dynamics of ubiquitin in microcrystals, and in particular a mutant in a region that undergoes microsecond motions in a β-turn region in the wild-type protein. We use (15)N R1ρ relaxation measurements as a function of the radio-frequency (RF) field strength, i.e. relaxation dispersion, to probe how the G53A mutation alters these dynamics...
April 14, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28437584/high-field-95-mo-and-183-w-static-and-mas-nmr-study-of-polyoxometalates
#7
Mohamed Haouas, Julien Trébosc, Catherine Roch-Marchal, Emmanuel Cadot, Francis Taulelle, Charlotte Martineau-Corcos
The potential of high-field NMR to measure solid-state (95) Mo and (183) W NMR in polyoxometalates (POMs) is explored using some archetypical structures like Lindqvist, Keggin, and Dawson as model compounds that are well characterized in solution. NMR spectra in static and under magic angle spinning (MAS) were obtained, and their analysis allowed extraction of the NMR parameters, including chemical shift anisotropy (CSA) and quadrupolar coupling parameters. Despite the inherent difficulties of measurement in solid state of these low-gamma NMR nuclei, due mainly to the low spectral resolution and poor signal-to-noise ratio, the observed global trends compare well with the solution state NMR data...
April 24, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28435390/synthesis-and-characterization-of-silver-nanoparticles-from-bis-alkylamine-silver-carboxylate-precursors
#8
Pawel Uznanski, Joanna Zakrzewska, Frederic Favier, Slawomir Kazmierski, Ewa Bryszewska
A comparative study of amine and silver carboxylate adducts [R1COOAg-2(R2NH2)] (R1 = 1, 7, 11; R2 = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, (13)C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies ((1)H and (13)C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units...
2017: Journal of Nanoparticle Research: An Interdisciplinary Forum for Nanoscale Science and Technology
https://www.readbyqxmd.com/read/28433869/community-based-barriers-to-the-wider-acceptance-of-solid-state-nmr
#9
Paul Jonsen
During August 2015, the author surveyed 76 solid state NMR scientists from materials science to biology, academic to industrial, based in North America, Europe, India, China, Japan and Australia. The subject concerned barriers to the wider acceptance of solid state NMR and included the various barriers based on experimental, funding, vendor based and community aspects. This survey was confidential. However, many of the survey participants requested that at least the results of the part of the survey relevant to our community be made public...
February 9, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28433479/modeling-short-range-substitution-order-and-disorder-in-crystals-application-to-the-ga-si-distribution-in-a-natrolite-zeolite
#10
Sylvian Cadars, Nak Ho Ahn, Kirill Okhotnikov, Jiho Shin, Aurélie Vicente, Suk Bong Hong, Christian Fernandez
Atomic substitutions are a central feature of the physicochemical properties of an increasing number of solid-state materials. The complexity that this chemical disorder locally generates in otherwise crystalline solids poses a major challenge to the understanding of the relationships between the structure and properties of materials at the atomic and molecular level. Strategies designed to efficiently explore the ensemble of local chemical environments present in disordered crystals and predict their signatures in local spectroscopies such as solid-state nuclear magnetic resonance (NMR) are therefore essential...
April 13, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28433023/rotational-resonance-for-a-heteronuclear-spin-pair-under-magic-angle-spinning-in-solid-state-nmr
#11
Takayuki Kamihara, K Takegoshi
Rotational resonance (R2) is one of the widely applied techniques in solid-state NMR for recoupling a homonuclear dipolar interaction under magic-angle spinning (MAS). R2 occurs as the result of interference between the difference of the chemical shifts and MAS. In this work, we extend R2 to a heteronuclear dipolar interaction in the interaction frame of RF irradiation. Based on the average Hamiltonian theory, we show that the recoupling of the heteronuclear dipolar (I-S) interaction occurs at the recoupling conditions written as ΩI(')±ΩS(')=kωr (k=0,±1,±2), where ΩX(') is the RF offset for spin-X (X = I or S) scaled by RF irradiation...
April 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28430190/tuning-underwater-adhesion-with-cation-%C3%AF-interactions
#12
Matthew A Gebbie, Wei Wei, Alex M Schrader, Thomas R Cristiani, Howard A Dobbs, Matthew Idso, Bradley F Chmelka, J Herbert Waite, Jacob N Israelachvili
Cation-π interactions drive the self-assembly and cohesion of many biological molecules, including the adhesion proteins of several marine organisms. Although the origin of cation-π bonds in isolated pairs has been extensively studied, the energetics of cation-π-driven self-assembly in molecular films remains uncharted. Here we use nanoscale force measurements in combination with solid-state NMR spectroscopy to show that the cohesive properties of simple aromatic- and lysine-rich peptides rival those of the strong reversible intermolecular cohesion exhibited by adhesion proteins of marine mussel...
May 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28426169/microsecond-dynamics-in-ubiquitin-probed-by-solid-state-nmr-15n-r1rho-relaxation-experiments-under-fast-mas-60-110-khz
#13
Nils-Alexander Lakomek, Susanne Penzel, Alons Lends, Riccardo Cadalbert, Matthias Ernst, Beat H Meier
15N R1ρ relaxation experiments in solid-state NMR are sensitive to timescales and amplitudes of internal protein motions in the hundreds of ns to µs time window, difficult to probe with solution-state NMR. Using 15N R1ρ relaxation experiments with variable MAS frequency (60-110 kHz) and a model-free analysis, we describe an approach to detect hundreds of ns to low µs protein dynamics and determine residue-specific correlation times from the ratio of 15N R1ρ rate constants at different MAS frequencies. We find that microcrystalline ubiquitin exhibits small-amplitude dynamics on a timescale of about 1 µs across the entire protein, and larger amplitude motions, also on the 1 µs timescale, for several sites, including the β1-β2 turn and the N-terminus of the α-helix...
April 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28425709/beyond-structural-biology-to-functional-biology-solid-state-nmr-experiments-and-strategies-for-understanding-the-m2-proton-channel-conductance
#14
Huajun Qin, Yimin Miao, Timothy A Cross, Riqiang Fu
In terms of structural biology, solid-state NMR experiments and strategies have been well established for resonance assignments leading to the determination of three-dimensional structures of insoluble membrane proteins in their native-like environment. It is also known that NMR has the unique capabilities to characterize structure-function relationships of membrane-bound biological systems beyond structural biology. Here, we report on solid-state NMR experiments and strategies for extracting functional activities on a sub-msec time scale...
April 20, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28423212/persistent-radicals-of-self-assembled-benzophenone-bis-urea-macrocycles-characterization-and-application-as-a-polarizing-agent-for-solid-state-dnp-mas-spectroscopy
#15
Baillie A DeHaven, John T Tokarski, Arthur A Korous, Frederic Mentink-Vigier, Thomas M Makris, Alexander M Brugh, Malcolm D E Forbes, Johan van Tol, Clifford Russ Bowers, Linda S Shimizu
UV-irradiation of a self-assembled benzophenone bis-urea macrocycle generates μM amounts of radicals that persist for weeks under ambient conditions. High-Field EPR and variable temperature X-band EPR studies suggest a resonance stabilized radical pair through H-abstraction. These endogenous radicals were applied as a polarizing agent for magic angle spinning (MAS) dynamic nuclear polarization (DNP) NMR enhancement. The field-stepped DNP enhancement profile exhibits a sharp peak with a maximum enhancement of εon/off = 4 superimposed on a nearly constant DNP enhancement of εon/off = 2 over a broad field range...
April 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28422500/influence-of-13-c-isotopic-labeling-location-on-dynamic-nuclear-polarization-of-acetate
#16
Peter Niedbalski, Christopher Parish, Andhika Kiswandhi, Zoltan Kovacs, Lloyd Lumata
Dynamic nuclear polarization (DNP) via the dissolution method has alleviated the insensitivity problem in liquid-state nuclear magnetic resonance (NMR) spectroscopy by amplifying the signals by several thousand-fold. This NMR signal amplification process emanates from the microwave-mediated transfer of high electron spin alignment to the nuclear spins at high magnetic field and cryogenic temperature. Since the interplay between the electrons and nuclei is crucial, the chemical composition of a DNP sample such as the type of free radical used, glassing solvents, or the nature of the target nuclei can significantly affect the NMR signal enhancement levels that can be attained with DNP...
April 24, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28416656/effect-of-cholesterol-on-the-molecular-structure-and-transitions-in-a-clinical-grade-lung-surfactant-extract
#17
Jenny Marie Andersson, Carl Grey, Marcus Larsson, Tiago Mendes Ferreira, Emma Sparr
The lipid-protein film covering the interface of the lung alveolar in mammals is vital for proper lung function and its deficiency is related to a range of diseases. Here we present a molecular-level characterization of a clinical-grade porcine lung surfactant extract using a multitechnique approach consisting of [Formula: see text]-[Formula: see text] solid-state nuclear magnetic spectroscopy, small- and wide-angle X-ray scattering, and mass spectrometry. The detailed characterization presented for reconstituted membranes of a lung extract demonstrates that the molecular structure of lung surfactant strongly depends on the concentration of cholesterol...
April 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28415526/effect-of-variable-aminoalkyl-chains-on-chemical-grafting-of-cellulose-nanofiber-and-their-antimicrobial-activity
#18
Seema Saini, Mohamed Naceur Belgacem, Julien Bras
Recent focus on the preparation of antimicrobial surfaces using cellulose nanofibers (CNF) has gained considerable attention. In this work, functionalization of CNF films in 100% aqueous solution with three different aminosilanes, including 3-aminopropyl trimethoxysilane (APMS), 2-aminoethyl 3-aminopropyl trimethoxysilane (DAMS)and 3-2-(2-aminoethylamino) ethylamino propyl-trimethoxysilane (TAMS) is reported for the fabrication of contact active antimicrobial materials. Grafted CNF films were comprehensively characterized by FTIR, TGA, contact angle, elemental analysis, solid-state (29)Si NMR, FEG-SEM and SEM-EDX...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28414225/reversible-gas-solid-ammonia-n-h-bond-activation-mediated-by-an-organopalladium-complex
#19
Marina Juribašić Kulcsár, Ivan Halasz, Ana Budimir, Krunoslav Užarević, Stipe Lukin, Andrea Monas, Franziska Emmerling, Janez Plavec, Manda Ćurić
N-H bond activation of gaseous ammonia is achieved at room temperature in a reversible solvent-free reaction using a solid dicyclopalladated azobenzene complex. Monitoring of the gas-solid reaction in real-time by in situ solid-state Raman spectroscopy enabled a detailed insight into the stepwise activation pathway proceeding to the final amido complex via a stable diammine intermediate. Gas-solid synthesis allowed for isolation and subsequent structural characterization of the intermediate and the final amido product, which presents the first dipalladated complex with the Pd(II)-(μ-NH2)-Pd(II) bridge...
April 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28412819/d-%C3%AE-tocopheryl-polyethylene-glycol-succinate-micelles-structure-kinetic-pathways-and-modulation-by-cyclodextrins
#20
Joan Puig-Rigall, Isabelle Grillo, Cecile A Dreiss, Gustavo González-Gaitano
The aggregation and structure of D-α-tocopheryl polyethylene glycol succinate micelles, TPGS-1000, an amphiphilic derivative of vitamin E, were characterized by scattering and spectroscopic methods, and the impact of different cyclodextrins (CDs) on the self-assembly studied, with the view of combining these two versatile pharmaceutical excipients in drug formulations. Combined SANS, DLS, time-resolved and steady-state fluorescence emission experiments revealed a core-shell architecture with a high aggregation number (Nagg ~ 100) and a highly hydrated PEO corona (~ 11 molecules of solvent per EO unit)...
April 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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