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https://www.readbyqxmd.com/read/28402625/interplay-of-internal-structure-and-interfaces-on-the-emitting-properties-of-hybrid-zno-hierarchical-particles
#1
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-vinyl-pyrrolidone (ZnO/PVP) mesocrystals is investigated in details 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 the emission from defects in the visible is not observed...
April 12, 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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
https://www.readbyqxmd.com/read/28191584/sizable-dynamics-in-small-pores-co2-location-and-motion-in-the-%C3%AE-mg-formate-metal-organic-framework
#16
Yuanjun Lu, Bryan E G Lucier, Yue Zhang, Pengju Ren, Anmin Zheng, Yining Huang
Metal-organic frameworks (MOFs) are promising materials for carbon dioxide (CO2) adsorption and storage; however, many details regarding CO2 dynamics and specific adsorption site locations within MOFs remain unknown, restricting the practical uses of MOFs for CO2 capture. The intriguing α-magnesium formate (α-Mg3(HCOO)6) MOF can adsorb CO2 and features a small pore size. Using an intertwined approach of (13)C solid-state NMR (SSNMR) spectroscopy, (1)H-(13)C cross-polarization SSNMR, and computational molecular dynamics (MD) simulations, new physical insights and a rich variety of information have been uncovered regarding CO2 adsorption in this MOF, including the surprising suggestion that CO2 motion is restricted at elevated temperatures...
February 13, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28166408/characterization-of-the-particle-size-and-polydispersity-of-dicumarol-using-solid-state-nmr-spectroscopy
#17
Kassibla Elodie Dempah, Joseph W Lubach, Eric J Munson
A variety of particle sizes of a model compound, dicumarol, were prepared and characterized in order to investigate the correlation between particle size and solid-state NMR (SSNMR) proton spin-lattice relaxation ((1)H T1) times. Conventional laser diffraction and scanning electron microscopy were used as particle size measurement techniques and showed crystalline dicumarol samples with sizes ranging from tens of micrometers to a few micrometers. Dicumarol samples were prepared using both bottom-up and top-down particle size control approaches, via antisolvent microprecipitation and cryogrinding...
February 15, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28157561/indirect-detection-of-infinite-speed-mas-solid-state-nmr-spectra
#18
Frédéric A Perras, Amrit Venkatesh, Michael P Hanrahan, Tian Wei Goh, Wenyu Huang, Aaron J Rossini, Marek Pruski
Heavy spin-1/2 nuclides are known to possess very large chemical shift anisotropies that can challenge even the most advanced magic-angle-spinning (MAS) techniques. Wide manifolds of overlapping spinning sidebands and insufficient excitation bandwidths often obfuscate meaningful spectral information and force the use of static, low-resolution solid-state (SS)NMR methods for the characterization of materials. To address these issues, we have merged fast-magic-angle-turning (MAT) and dipolar heteronuclear multiple-quantum coherence (D-HMQC) experiments to obtain D-HMQC-MAT pulse sequences which enable the rapid acquisition of 2D SSNMR spectra that correlate isotropic (1)H chemical shifts to the indirectly detected isotropic "infinite-MAS" spectra of heavy spin-1/2 nuclides...
January 18, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28130009/practical-considerations-for-the-acquisition-of-ultra-wideline-14-n-nmr-spectra
#19
Stanislav L Veinberg, Austin W Lindquist, Michael J Jaroszewicz, Robert W Schurko
Several considerations for the acquisition, processing, and analysis of high quality ultra-wideline (UW) (14)N solid-state NMR (SSNMR) powder patterns under static conditions are discussed. It is shown that the (14)N quadrupolar parameters may be determined accurately using the frequencies of only two discontinuities in (14)N NMR powder patterns that are dominated by the first-order quadrupolar interaction, thereby eliminating the need for the acquisition of the entire pattern and concomitantly reducing experimental time...
December 21, 2016: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28094949/how-high-concentrations-of-proteins-stabilize-the-amorphous-state-of-calcium-orthophosphate-a-solid-state-nuclear-magnetic-resonance-nmr-study-of-the-casein-case
#20
Paulo De Sa Peixoto, Juliana V C Silva, Guillaume Laurent, Marc Schmutz, Daniel Thomas, Antoine Bouchoux, Geneviève Gésan-Guiziou
Understanding how proteins stabilize amorphous calcium ortho-phosphate (ACP) phases is of great importance in biology and for pharmaceutical or food applications. Until now, most of the former investigations about ACP-protein stability and equilibrium were performed under conditions where ACP colloidal nanoclusters are surrounded by low to moderate concentrations of peptides or proteins (15-30 g L(-1)). As a result, the question of ACP-protein interactions in highly concentrated protein systems has clearly been overlooked, whereas it corresponds to actual industrial conditions such as drying or membrane filtration in the dairy industry for instance...
January 30, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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