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https://www.readbyqxmd.com/read/28334391/sediment-anoxia-limits-microbial-driven-seagrass-carbon-remineralization-under-warming-conditions
#1
Stacey M Trevathan-Tackett, Justin R Seymour, Daniel A Nielsen, Peter I Macreadie, Thomas C Jeffries, Jonathan Sanderman, Jeff Baldock, Johanna M Howes, Andrew D L Steven, Peter Ralph
Seagrass ecosystems are significant carbon sinks, and their resident microbial communities ultimately determine the quantity and quality of carbon sequestered. However, environmental perturbations have been predicted to affect microbial-driven seagrass decomposition and subsequent carbon sequestration. Utilizing techniques including 16S-rDNA sequencing, solid-state NMR and microsensor profiling, we tested the hypothesis that elevated seawater temperatures and eutrophication enhance the microbial decomposition of seagrass leaf detritus and rhizome/root tissues...
March 15, 2017: FEMS Microbiology Ecology
https://www.readbyqxmd.com/read/28332683/tailoring-adsorption-induced-phase-transitions-in-the-pillared-layer-type-metal-organic-framework-dut-8-ni
#2
Negar Kavoosi, Volodymyr Bon, Irena Senkovska, Simon Krause, Cesare Atzori, Francesca Bonino, Julia Pallmann, Silvia Paasch, Eike Brunner, Stefan Kaskel
Tailoring the characteristics of gating transitions in the porous network, Ni2(ndc)2dabco (ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane), also termed DUT-8(Ni) (DUT = Dresden University of Technology), was achieved by systematically adjusting the critical synthesis parameters. The impact of the starting composition and solvent mixtures in the synthesis was found to critically affect the guest-response properties of the obtained materials. A comprehensive set of physical characterization methods, namely thermal analysis, (1)H NMR of digested crystals, solid state (13)C NMR, PXRD, SEM, IR and Raman spectroscopy shows that the crystallite size is a crucial factor, determining the differing characteristics such as "gate pressure" and adsorption capacity in the guest-responsive switching behaviour of DUT-8...
March 23, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28328222/correction-to-characterization-of-the-particle-size-and-polydispersity-of-dicumarol-using-solid-state-nmr-spectroscopy
#3
Kassibla Elodie Dempah, Joseph W Lubach, Eric J Munson
No abstract text is available yet for this article.
March 22, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28327749/mono-and-polynuclear-ag-i-complexes-of-n-functionalized-bis-diphenylphosphino-amine-dppa-type-ligands-synthesis-solid-state-structures-and-reactivity
#4
Alessio Ghisolfi, Christophe Fliedel, Pierre de Frémont, Pierre Braunstein
The reactivity of the N-functionalized DPPA-type ligands (Ph2P)2N(p-Z)C6H4 [Z = H (1a), SMe (1b), OMe (1c)] with AgBF4 was investigated and revealed an unexpected influence of the para substituent Z of the N-aryl ligand. In acetone, the mononuclear bis-chelated [Ag{(1a-1c)-P,P}2]BF4 (2a·BF4-2c·BF4) and dinuclear bridged [Ag2{μ2-(1a-1c)-P,P}2](BF4)2 [3a·(BF4)2-3c·(BF4)2] complexes were obtained with a 1 : 2 and 1 : 1 AgBF4/ligand molar ratio, respectively. While the molecular structures of 2a·BF4 and 2b·BF4 determined in the solid-state by X-ray diffraction revealed their mononuclear nature and the absence of cation/anion interaction, complexes 3b·(BF4)2 and 3c·(BF4)2 form 2D coordination polymers through intermolecular Ag-S or Ag-O interactions, respectively, involving the N-function of the respective DPPA-type ligand, and display direct interactions between one BF4 anion and both Ag(i) cations...
March 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28327736/a-dnp-supported-solid-state-nmr-study-of-carbon-species-in-fluid-catalytic-cracking-catalysts
#5
Deni Mance, Johan van der Zwan, Marjolein E Z Velthoen, Florian Meirer, Bert M Weckhuysen, Marc Baldus, Eelco T C Vogt
A combination of solid-state NMR techniques supported by EPR and SEM-EDX experiments was used to localize different carbon species (coke) in commercial fluid catalytic cracking catalysts. Aliphatic coke species formed during the catalytic process and aromatic coke species deposited directly from the feedstock respond differently to dynamic nuclear polarization signal enhancement in integral and crushed FCC particles, indicating that aromatic species are mostly concentrated on the outside of the catalyst particles, whereas aliphatic species are also located on the inside of the FCC particles...
March 22, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28325334/citric-acid-crosslinked-%C3%AE-cyclodextrin-carboxymethylcellulose-hydrogel-films-for-controlled-delivery-of-poorly-soluble-drugs
#6
Vishwajeet Sampatrao Ghorpade, Adhikrao Vyankatrao Yadav, Remeth Jacky Dias
Citric acid crosslinked β-cyclodextrin-carboxymethylcellulose (βCD-CMC) hydrogel films were prepared by esterification-crosslinking method for the controlled release of ketoconazole (model drug). The hydrogel films were evaluated for active βCD content, carboxyl content, swelling ratio, drug loading and release, and hemolytic activity. The structural characterization was carried out using solid state (13)C NMR, ATR-FTIR, TGA and DSC analysis. The βCD-CMC hydrogel films showed increase in active βCD content swelling ratio and drug loading with increase in the concentration of βCD in the feed...
May 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28325108/relationship-between-water-structure-and-properties-of-poly-methyl-methacrylate-b-2-hydroxyethyl-methacrylate-by-solid-state-nmr
#7
Akira Mochizuki, Yuko Miwa, Riko Miyoshi, Takahiro Namiki
We previously reported that the platelet compatibility of methyl methacrylate (MMA)-2-hydroxyethyl methacrylate (HEMA) diblock copolymers is related to the characteristic water structure in the copolymer, as the copolymer has an excess amount of nonfreezing water when compared with that estimated from the amounts of water in HEMA and MMA homopolymers. Thus, in this study, the relationship between water structure and polymer structure, including the heterogeneity and mobility of the copolymer, was investigated using differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) spectroscopy...
March 22, 2017: Journal of Biomaterials Science. Polymer Edition
https://www.readbyqxmd.com/read/28322472/molecular-chemistry-and-engineering-of-boron-modified-polyorganosilazanes-as-new-processable-and-functional-sibcn-precursors
#8
Samuel Bernard, Antoine Viard, Diane Fonblanc, Marion Schmidt, Abhijeet Lale, Chrystelle Salameh, Anne Soleilhavoup, Mélanie Wynn, Philippe Champagne, Sophie Cerneaux, Florence Babonneau, Georges Chollon, Fabrice Rossignol, Christel Gervais
A series of boron-modified polyorganosilazanes was synthesized from a poly(vinylmethyl-co-methyl)silazane and controlled borane dimethyl sulfide amounts. The role of the chemistry behind their syntheses has been studied in details by solid-state NMR, FT-IR and elemental analyses. Then, the intimate relationship between the chemistry and the processability of these polymers was discussed. Polymers with low boron contents display the appropriate requirements for facile processing in solution such as impregnation of host carbon materials resulting in the design of mesoporous monoliths with high specific surface area after pyrolysis...
March 21, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28319405/heptacene-characterization-in-solution-in-the-solid-state-and-in-films
#9
Ralf Einholz, Treliant Fang, Robert Berger, Peter Grüninger, Andreas Früh, Thomas Chassé, Reinhold F Fink, Holger F Bettinger
Acenes comprise an important class of organic semiconducting materials. As graphene nanoribbons of ultimate width, they are valuable atom-precise model systems for studying the properties of this form of nanoscale carbon materials. Heptacene is the smallest member of the acene series that could only be studied under matrix isolation conditions. Its existence in bulk had never been positively confirmed, despite efforts dating back more than 70 years. We report that the reduction of 7,16-heptacenequinone produces a mixture of two diheptacene molecules...
March 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28319391/synthesis-isotopic-enrichment-and-solid-state-nmr-characterization-of-zeolites-derived-from-the-assembly-disassembly-organisation-reassembly-process
#10
Giulia P M Bignami, Daniel M Dawson, Valerie R Seymour, Paul S Wheatley, Russell Edward Morris, Sharon E Ashbrook
The great utility and importance of zeolites in fields as diverse as industrial catalysis and medicine has driven considerable interest in the ability to target new framework types with novel properties and applications. The recently-introduced and unconventional Assembly, Disassembly, Organization, Reassembly (ADOR) method represents one exciting new approach to obtain solids with targeted structures by selectively disassembling pre-prepared hydrolytically-unstable frameworks, and then reassembling the resulting products to form materials with new topologies...
March 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28319293/bis-gadolinium-complexes-for-solid-effect-and-cross-effect-dynamic-nuclear-polarization
#11
Monu Kaushik, Mian Qi, Adelheid Godt, Björn Corzilius
High-spin complexes act as polarizing agents (PAs) for dynamic nuclear polarization (DNP) in solid-state NMR spectroscopy and feature promising aspects towards biomolecular DNP. We present a study on bis(Gd-chelate)s which enable cross effect (CE) DNP owing to spatial confinement of two dipolar-coupled electron spins. Their well-defined Gd⋅⋅⋅Gd distances in the range of 1.2-3.4 nm allowed us to elucidate the Gd⋅⋅⋅Gd distance dependence of the DNP mechanism and NMR signal enhancement. We found that Gd⋅⋅⋅Gd distances above 2...
March 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28319116/quenched-hydrogen-deuterium-exchange-nmr-of-a-disease-relevant-a%C3%AE-1-42-amyloid-polymorph
#12
Marielle Aulikki Wälti, Julien Orts, Roland Riek
Alzheimer's disease is associated with the aggregation into amyloid fibrils of Aβ(1-42) and Aβ(1-40) peptides. Interestingly, these fibrils often do not obtain one single structure but rather show different morphologies, so-called polymorphs. Here, we compare quenched hydrogen-deuterium (H/D) exchange of a disease-relevant Aβ(1-42) fibril for which the 3D structure has been determined by solid-state NMR with H/D exchange previously determined on another structural polymorph. This comparison reveals secondary structural differences between the two polymorphs suggesting that the two polymorphisms can be classified as segmental polymorphs...
2017: PloS One
https://www.readbyqxmd.com/read/28318261/expanded-rosarin-a-versatile-fullerene-c60-receptor
#13
Xian-Sheng Ke, Taeyeon Kim, James T Brewster, Vincent M Lynch, Dongho Kim, Jonathan L Sessler
An expanded rosarian (P3P6) with a bowl-like conformation has been prepared and characterized. It is prepared in a one pot procedure that involves condensing a bispyrrole pyridine precursor (P1P2) with benzaldehyde, followed by oxidation. Single crystal X-ray diffraction analysis reveals a bowl-like conformation in the solid state with an upper rim diameter defined by the meso-phenyl substituents of ca. 13.5 Å and a depth of roughly 6.3 Å. P3P6 forms both 1:1 and 2:1 complexes with C60 in the solid state...
March 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28317055/electronic-and-relativistic-contributions-to-ion-pairing-in-polyoxometalate-model-systems
#14
Dylan J Sures, Stefano A Serapian, Károly Kozma, Pedro I Molina, Carles Bo, May Nyman
Ion pairs and solubility related to ion-pairing in water influence many processes in nature and in synthesis including efficient drug delivery, contaminant transport in the environment, and self-assembly of materials in water. Ion pairs are difficult to observe spectroscopically because they generally do not persist unless extreme solution conditions are applied. Here we demonstrate two advanced techniques coupled with computational studies that quantify the persistence of ion pairs in simple solutions and offer explanations for observed solubility trends...
March 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28314145/preparation-of-polyhedral-oligomeric-silsesquioxane-based-cross-linked-inorganic-organic-nanohybrid-as-adsorbent-for-selective-removal-of-acidic-dyes-from-aqueous-solution
#15
Jiawei Liu, Heng Yu, Qingmei Liang, Yanna Liu, Jiwei Shen, Quan Bai
A cross-linked polyhedral oligomeric silsesquioxane (POSS) nanohybrid is synthesized through Schiff base chemistry by using octa-amino POSS as building blocks and glutaraldehyde as dual functional reagent. The obtained nanohybrid is characterized by FT-IR, solid-state (29)Si NMR, SEM, TEM, TGA and N2 adsorption-desorption isotherm, and the results demonstrate the successful cross-linkage between POSS molecules, forming block-like irregular nanoparticles with a specific surface area of 42.8m(2)g(-1). As a novel solid-phase adsorbent, cross-linked POSS nanohybrid exhibits selective adsorption properties for acidic dyes, i...
March 7, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28306264/correlating-carrier-density-and-emergent-plasmonic-features-in-cu2-xse-nanoparticles
#16
Lauren E Marbella, Xing Yee Gan, Derrick C Kaseman, Jill E Millstone
Recently, a wide variety of new nanoparticle compositions have been identified as potential plasmonic materials including earth-abundant metals such as aluminum, highly doped semiconductors, as well as metal pnictides. For semiconductor compositions, plasmonic properties may be tuned not only by nanoparticle size and shape, but also by charge carrier density which can be controlled via a variety of intrinsic and extrinsic doping strategies. Current methods to quantitatively determine charge carrier density primarily rely on interpretation of the nanoparticle extinction spectrum...
March 17, 2017: Nano Letters
https://www.readbyqxmd.com/read/28299727/metal-fluorides-tools-for-structural-and-computational-analysis-of-phosphoryl-transfer-enzymes
#17
REVIEW
Yi Jin, Robert W Molt, G Michael Blackburn
The phosphoryl group, PO3(-), is the dynamic structural unit in the biological chemistry of phosphorus. Its transfer from a donor to an acceptor atom, with oxygen much more prevalent than nitrogen, carbon, or sulfur, is at the core of a great majority of enzyme-catalyzed reactions involving phosphate esters, anhydrides, amidates, and phosphorothioates. The serendipitous discovery that the phosphoryl group could be labeled by "nuclear mutation," by substitution of PO3(-) by MgF3(-) or AlF4(-), has underpinned the application of metal fluoride (MF x ) complexes to mimic transition states for enzymatic phosphoryl transfer reactions, with sufficient stability for experimental analysis...
April 2017: Topics in Current Chemistry (Journal)
https://www.readbyqxmd.com/read/28299622/molecular-interactions-of-the-inclusion-complexes-of-hinokitiol-and-various-cyclodextrins
#18
Rina Suzuki, Yutaka Inoue, Sontaya Limmatvapirat, Isamu Murata, Ikuo Kanamoto
The aim of this study was to prepare inclusion complexes of hinokitiol (HT)/α-cyclodextrin (α-CD) and HT/β-cyclodextrin (β-CD) by cogrinding and to evaluate the differences in their formation. The physical properties of the preparation were evaluated by Job's plot, phase solubility studies, differential scanning calorimetry, powder X-ray diffraction, solid fluorescence spectra, and infrared absorption spectra. Intermolecular interaction in the solid state was confirmed to be in the ratios HT/α-CD = 1/2 and HT/β-CD = 1/1...
March 15, 2017: AAPS PharmSciTech
https://www.readbyqxmd.com/read/28298092/significance-of-symmetry-in-the-nuclear-spin-hamiltonian-for-efficient-heteronuclear-dipolar-decoupling-in-solid-state-nmr-a-floquet-description-of-supercycled-rcw-schemes
#19
Asif Equbal, Ravi Shankar, Michal Leskes, Shimon Vega, Niels Chr Nielsen, P K Madhu
Symmetry plays an important role in the retention or annihilation of a desired interaction Hamiltonian in NMR experiments. Here, we explore the role of symmetry in the radio-frequency interaction frame Hamiltonian of the refocused-continuous-wave (rCW) pulse scheme that leads to efficient (1)H heteronuclear decoupling in solid-state NMR. It is demonstrated that anti-periodic symmetry of single-spin operators (Ix, Iy, Iz) in the interaction frame can lead to complete annihilation of the (1)H-(1)H homonuclear dipolar coupling effects that induce line broadening in solid-state NMR experiments...
March 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28294184/crystallization-and-hardening-of-poly-ethylene-co-vinyl-acetate-mouthguards-during-routine-use
#20
Ryoko Kuwahara, Ryotaro Tomita, Natsumi Ogawa, Kazunori Nakajima, Tomotaka Takeda, Hiroki Uehara, Takeshi Yamanobe
Mouthguards (MGs) made from poly(ethylene-co-vinyl acetate) (EVA) are widely used in contact sports to prevent injuries such as breaking teeth and lip lacerations and to reduce brain concussion. However, the changes in morphology and the molecular mobility of EVA, which can affect its physical properties during practical usage, have not been precisely examined. Therefore, we attempted to determine the main factors which lead to changes in MG performance after one season of practical use by high school rugby players...
March 15, 2017: Scientific Reports
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