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https://www.readbyqxmd.com/read/28511991/calculation-of-the-cross-sectional-shape-of-a-fibril-from-equatorial-scattering
#1
Biel Roig-Solvas, Lee Makowski
An alternate formulation of helical diffraction theory is used to generate cross-sectional shapes of fibrous structures from equatorial scattering. We demonstrate this approach with computationally generated scattering intensities and then apply it to scattering data from Tobacco Mosaic Virus (TMV) and in vitro assembled fibrils of Aβ40 peptides. Refining the cross-sectional shape of TMV from SAXS data collected on a 26 mg/ml solution resulted in a circular shape with outer diameter of ∼ 180Å and inner diameter of ∼ 40Å consistent with the known structure of TMV...
May 13, 2017: Journal of Structural Biology
https://www.readbyqxmd.com/read/28501588/oligomeric-structure-of-anabaena-sensory-rhodopsin-in-a-lipid-bilayer-environment-by-combining-solid-state-nmr-and-long-range-deer-constraints
#2
Sergey Milikisiyants, Shenlin Wang, Rachel A Munro, Matthew Donohue, Meaghan E Ward, David Bolton, Leonid S Brown, Tatyana I Smirnova, Vladimir Ladizhansky, Alex I Smirnov
Oligomerization of membrane proteins is common in nature. Here, we combine spin-labeling Double Electron-Electron Resonance (DEER) and solid-state NMR (ssNMR) spectroscopy to refine the structure of an oligomeric integral membrane protein, Anabaena Sensory Rhodopsin (ASR), reconstituted in a lipid environment. An essential feature of such a combined approach is that it provides structural distance restraints spanning a range of ca. 3-60Å, while using the same sample preparation (i.e., mutations, paramagnetic labeling, and reconstitution in lipid bilayers) for both ssNMR and DEER...
May 10, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28480926/confinement-effects-of-a-crystalline-sponge-on-ferrocene-and-ferrocene-carboxaldehyde
#3
Gabriel Brunet, Damir A Safin, Koen Robeyns, Glenn A Facey, Ilia Korobkov, Yaroslav Filinchuk, Muralee Murugesu
The pivotal role of ππ interactions in the inclusion behaviour of a series of organometallic sandwich compounds is studied through single-crystal X-ray diffraction. The confinement effects of a crystalline sponge host are investigated where, notably, we observe an enhanced rotation of the ligand ring once encapsulated by the nanoporous framework, as evidenced by SSNMR experiments.
May 8, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28471174/investigating-sodium-storage-mechanisms-in-tin-anodes-a-combined-pair-distribution-function-analysis-density-functional-theory-and-solid-state-nmr-approach
#4
Joshua M Stratford, Martin Mayo, Phoebe K Allan, Oliver Pecher, Olaf J Borkiewicz, Kamila M Wiaderek, Karena W Chapman, Chris J Pickard, Andrew J Morris, Clare P Grey
The alloying mechanism of high-capacity tin anodes for sodium-ion batteries is investigated using a combined theoretical and experimental approach. Ab initio random structure searching (AIRSS) and high-throughput screening using a species-swap method provide insights into a range of possible sodium-tin structures. These structures are linked to experiments using both average and local structure probes in the form of operando pair distribution function analysis, X-ray diffraction, and (23)Na solid-state nuclear magnetic resonance (ssNMR), along with ex situ (119)Sn ssNMR...
May 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28455777/insights-into-nano-and-micron-scale-phase-separation-in-amorphous-solid-dispersions-using-fluorescence-based-techniques-in-combination-with-solid-state-nuclear-magnetic-resonance-spectroscopy
#5
Hitesh S Purohit, James D Ormes, Sugandha Saboo, Yongchao Su, Matthew S Lamm, Amanda K P Mann, Lynne S Taylor
PURPOSE: Miscibility between the drug and the polymer in an amorphous solid dispersion (ASD) is considered to be one of the most important factors impacting the solid state stability and dissolution performance of the active pharmaceutical ingredient (API). The research described herein utilizes emerging fluorescence-based methodologies to probe (im)miscibility of itraconazole (ITZ)-hydroxypropyl methylcellulose (HPMC) ASDs. METHODS: The ASDs were prepared by solvent evaporation with varying evaporation rates and were characterized by steady-state fluorescence spectroscopy, confocal imaging, differential scanning calorimetry (DSC), and solid state nuclear magnetic resonance (ssNMR) spectroscopy...
April 28, 2017: Pharmaceutical Research
https://www.readbyqxmd.com/read/28402625/interplay-of-internal-structure-and-interfaces-on-the-emitting-properties-of-hybrid-zno-hierarchical-particles
#6
Monica Distaso, Giovanni Bertoni, Stefano Todisco, Sergio Marras, Vito Gallo, Liberato Manna, Wolfgang Peukert
The design of hybrid organic/inorganic nanostructures with controlled assembly drives the development of materials with new or improved properties and superior performances. In this paper, the surface and internal structure of hybrid ZnO poly-N-vinylpyrrolidone (ZnO/PVP) mesocrystals are investigated in detail and correlated with their emitting properties. A photoluminescence study at room temperature reveals that the as-synthesized particles show a remarkable ultraviolet (UV) emission, whereas an emission from defects in the visible region is not observed...
April 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28368030/co-grinding-effect-on-crystalline-zaltoprofen-with-%C3%AE-cyclodextrin-cucurbit-7-uril-in-tablet-formulation
#7
Shanshan Li, Xiang Lin, Kailin Xu, Jiawei He, Hongqin Yang, Hui Li
This work aimed to investigate the co-grinding effects of β-cyclodextrin (β-CD) and cucurbit[7]uril (CB[7]) on crystalline zaltoprofen (ZPF) in tablet formulation. Crystalline ZPF was prepared through anti-solvent recrystallization and fully analyzed through single-crystal X-ray diffraction. Co-ground dispersions and mono-ground ZPF were prepared using a ball grinding process. Results revealed that mono-ground ZPF slightly affected the solid state, solubility, and dissolution of crystalline ZPF. Co-ground dispersions exhibited completely amorphous states and elicited a significant reinforcing effect on drug solubility...
April 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28353338/proton-based-ultrafast-magic-angle-spinning-solid-state-nmr-spectroscopy
#8
Rongchun Zhang, Kamal H Mroue, Ayyalusamy Ramamoorthy
Protons are vastly abundant in a wide range of exciting macromolecules and thus can be a powerful probe to investigate the structure and dynamics at atomic resolution using solid-state NMR (ssNMR) spectroscopy. Unfortunately, the high signal sensitivity, afforded by the high natural-abundance and high gyromagnetic ratio of protons, is greatly compromised by severe line broadening due to the very strong (1)H-(1)H dipolar couplings. As a result, protons are rarely used, in spite of the desperate need for enhancing the sensitivity of ssNMR to study a variety of systems that are not amenable for high resolution investigation using other techniques including X-ray crystallography, cryo-electron microscopy, and solution NMR spectroscopy...
March 29, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28315762/bionanocomposite-films-based-on-polysaccharides-from-banana-peels
#9
Túlio Ítalo S Oliveira, Morsyleide F Rosa, Michael J Ridout, Kathryn Cross, Edy S Brito, Lorena M A Silva, Selma E Mazzetto, Keith W Waldron, Henriette M C Azeredo
Pectin and cellulose nanocrystals (CNCs) isolated from banana peels were used to prepare films. The effects of a reinforcing phase (CNCs) and a crosslinker (citric acid, CA) on properties of pectin films were studied. Glycerol-plasticized films were prepared by casting, with different CNC contents (0-10wt%), with or without CA. Overall tensile properties were improved by intermediate CNC contents (around 5wt%). The water resistance and water vapor barrier properties were also enhanced by CNC. Evidences were found from Fourier Transform Infrared (FTIR) spectra supporting the occurrence of crosslinking by CA...
March 16, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28277547/backbone-assignment-of-perdeuterated-proteins-by-solid-state-nmr-using-proton-detection-and-ultrafast-magic-angle-spinning
#10
Pascal Fricke, Veniamin Chevelkov, Maximilian Zinke, Karin Giller, Stefan Becker, Adam Lange
Solid-state NMR (ssNMR) is a technique that allows the study of protein structure and dynamics at atomic detail. In contrast to X-ray crystallography and cryo-electron microscopy, proteins can be studied under physiological conditions-for example, in a lipid bilayer and at room temperature (0-35 °C). However, ssNMR requires considerable amounts (milligram quantities) of isotopically labeled samples. In recent years, (1)H-detection of perdeuterated protein samples has been proposed as a method of alleviating the sensitivity issue...
April 2017: Nature Protocols
https://www.readbyqxmd.com/read/28274845/exploring-the-interactions-of-irbesartan-and-irbesartan-2-hydroxypropyl-%C3%AE-cyclodextrin-complex-with-model-membranes
#11
Αdamantia S Liossi, Dimitrios Ntountaniotis, Tahsin F Kellici, Maria V Chatziathanasiadou, Grigorios Megariotis, Maria Mania, Johanna Becker-Baldus, Manfred Kriechbaum, Andraž Krajnc, Eirini Christodoulou, Clemens Glaubitz, Michael Rappolt, Heinz Amenitsch, Gregor Mali, Doros N Theodorou, Georgia Valsami, Marinos Pitsikalis, Hermis Iatrou, Andreas G Tzakos, Thomas Mavromoustakos
The interactions of irbesartan (IRB) and irbesartan-2-hydroxypropyl-β-cyclodextrin (HP-β-CD) complex with dipalmitoyl phosphatidylcholine (DPPC) bilayers have been explored utilizing an array of biophysical techniques ranging from differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), ESI mass spectrometry (ESI-MS) and solid state nuclear magnetic resonance (ssNMR). Molecular dynamics (MD) calculations have been also conducted to complement the experimental results. Irbesartan was found to be embedded in the lipid membrane core and to affect the phase transition properties of the DPPC bilayers...
March 6, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28267155/atomic-scale-structure-of-amorphous-aluminum-oxyhydroxide-oxide-and-oxycarbide-films-probed-by-very-high-field-27-al-nuclear-magnetic-resonance
#12
L Baggetto, V Sarou-Kanian, P Florian, A N Gleizes, D Massiot, C Vahlas
The atomic scale structure of aluminum in amorphous alumina films processed by direct liquid injection chemical vapor deposition from aluminum tri-isopropoxide (ATI) and dimethyl isopropoxide (DMAI) is investigated by solid-state (27)Al nuclear magnetic resonance (SSNMR) using a very high magnetic field of 20.0 T. This study is performed as a function of the deposition temperature in the range 300-560 °C, 150-450 °C, and 500-700 °C, for the films processed from ATI, DMAI (+H2O), and DMAI (+O2), respectively...
March 7, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28257016/solid-state-nmr-meets-electron-diffraction-determination-of-crystalline-polymorphs-of-small-organic-microcrystalline-samples
#13
Tetsuo Oikawa, Manabu Okumura, Tsunehisa Kimura, Yusuke Nishiyama
A combination of solid-state NMR (ssNMR) and electron diffraction (ED) has been used to determine the crystalline polymorphs in small-organic microcrystalline molecules. Although (13)C cross-polarization magic angle spinning (CPMAS) is a widely used method for determining crystalline polymorphs, even in a mixture, it sometimes fails if the molecular conformations are similar. On the other hand, ED can, in principle, differentiate crystalline forms with different lattice parameters, even when they have very similar molecular conformations...
March 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
https://www.readbyqxmd.com/read/28257009/-13-c-and-19-f-solid-state-nmr-and-x-ray-crystallographic-study-of-halogen-bonded-frameworks-featuring-nitrogen-containing-heterocycles
#14
Patrick M J Szell, Shaina A Gabriel, Russell D D Gill, Shirley Y H Wan, Bulat Gabidullin, David L Bryce
Halogen bonding is a noncovalent interaction between the electrophilic region of a halogen (σ-hole) and an electron donor. We report a crystallographic and structural analysis of halogen-bonded compounds by applying a combined X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (SSNMR) approach. Single-crystal XRD was first used to characterize the halogen-bonded cocrystals formed between two fluorinated halogen-bond donors (1,4-diiodotetrafluorobenzene and 1,3,5-trifluoro-2,4,6-triiodobenzene) and several nitrogen-containing heterocycles (acridine, 1,10-phenanthroline, 2,3,5,6-tetramethylpyrazine, and hexamethylenetetramine)...
March 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
https://www.readbyqxmd.com/read/28254276/effect-of-carbonate-substitution-on-physicochemical-and-biological-properties-of-silver-containing-hydroxyapatites
#15
Joanna Kolmas, Urszula Piotrowska, Marzena Kuras, Eliza Kurek
Ag(+)-substituted hydroxyapatites (Ag-HAs) and Ag(+)/CO3(2-)-co-substituted hydroxyapatites (Ag-CHAs) with two different concentrations of silver ions were synthesized by the standard precipitation method. For comparison, pure hydroxyapatite (HA) and carbonated hydroxyapatite (CHA) were synthesized using the same method. The obtained powders were examined by various physicochemical methods, such PXRD, TEM, FTIR and ssNMR. Elemental analysis was provided by WD-XRF and ICP-MS methods. The strains of Staphylococcus aureus and Escherichia coli were used to evaluate the antibacterial activity of the materials...
May 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28240335/dnp-enhanced-ultrawideline-207-pb-solid-state-nmr-spectroscopy-an-application-to-cultural-heritage-science
#16
Takeshi Kobayashi, Frédéric A Perras, Anna Murphy, Yao Yao, Jaclyn Catalano, Silvia A Centeno, Cecil Dybowski, Nicholas Zumbulyadis, Marek Pruski
Dynamic nuclear polarization (DNP) is used to enhance the (ultra)wideline (207)Pb solid-state NMR spectra of lead compounds of relevance in the preservation of cultural heritage objects. The DNP SSNMR experiments enabled, for the first time, the detection of the basic lead carbonate phase of the lead white pigment by (207)Pb SSNMR spectroscopy. Variable-temperature experiments revealed that the short T'2 relaxation time of the basic lead carbonate phase hinders the acquisition of the NMR signal at room temperature...
March 14, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28219822/ultrafast-acquisition-of-1-h-1-h-dipolar-correlation-experiments-in-spinning-elastomers
#17
Laetitia Rouger, Maxime Yon, Vincent Sarou-Kanian, Franck Fayon, Jean-Nicolas Dumez, Patrick Giraudeau
We show that two widely used 2D solid-state NMR (ssNMR) pulse sequences can be implemented in an ultrafast (UF) manner, and yield 2D spectra of elastomers in a single scan, under magic-angle spinning. UF 2D ssNMR provides an acceleration of one to several orders of magnitude for classic experiments.
February 9, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28217261/affinity-of-rimantadine-enantiomers-against-influenza-a-m2-protein-revisited
#18
Antonios Drakopoulos, Christina Tzitzoglaki, Chulong Ma, Kathrin Freudenberger, Anja Hoffmann, Yanmei Hu, Günter Gauglitz, Michaela Schmidtke, Jun Wang, Antonios Kolocouris
Recent findings from solid state NMR (ssNMR) studies suggested that the (R)-enantiomer of rimantadine binds to the full M2 protein with higher affinity than the (S)-enantiomer. Intrigued by these findings, we applied functional assays, such as antiviral assay and electrophysiology (EP), to evaluate the binding affinity of rimantadine enantiomers to the M2 protein channel. Unexpectedly, no significant difference was found between the two enantiomers. Our experimental data based on the full M2 protein function were further supported by alchemical free energy calculations and isothermal titration calorimetry (ITC) allowing an evaluation of the binding affinity of rimantadine enantiomers to the M2TM pore...
February 9, 2017: ACS Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28214103/tracking-the-evolution-and-differences-between-guest-induced-phases-of-ga-mil-53-via-ultra-wideline-69-71-ga-solid-state-nmr-spectroscopy
#19
Yue Zhang, Bryan E G Lucier, Victor V Terskikh, Renlong Zheng, Yining Huang
Ga-MIL-53 is a metal-organic framework (MOF) that exhibits a "breathing effect," in which the pore size and overall MOF topology can be influenced by temperature, pressure, and host-guest interactions. The phase control afforded by this flexible framework renders Ga-MIL-53 a promising material for guest storage and sensing applications. In this work, the structure and behavior of four Ga-MIL-53 phases (as, ht, enp and lt), along with CO2 adsorbed within Ga-MIL-53 at various loading levels, has been investigated using (69/71)Ga solid-state NMR (SSNMR) experiments at 21...
January 31, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28195488/surface-sensitive-nmr-detection-of-the-solid-electrolyte-interphase-layer-on-reduced-graphene-oxide
#20
Michal Leskes, Gunwoo Kim, Tao Liu, Alison L Michan, Fabien Aussenac, Patrick Dorffer, Subhradip Paul, Clare P Grey
Forming a stable solid electrolyte interphase (SEI) is critical for rechargeable batteries' performance and lifetime. Understanding its formation requires analytical techniques that provide molecular-level insight. Here, dynamic nuclear polarization (DNP) is utilized for the first time to enhance the sensitivity of solid-state NMR (ssNMR) spectroscopy to the SEI. The approach is demonstrated on reduced graphene oxide (rGO) cycled in Li-ion cells in natural abundance and (13)C-enriched electrolyte solvents. Our results indicate that DNP enhances the signal of outer SEI layers, enabling detection of natural abundance (13)C spectra from this component of the SEI on reasonable time frames...
February 21, 2017: Journal of Physical Chemistry Letters
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