Rotating frame resonance effects in high resolution carbon-13 NMR

1973 ◽  
Vol 58 (7) ◽  
pp. 3107 ◽  
Author(s):  
Ray Freeman
Keyword(s):  
High Resolution ◽  
Rotating Frame ◽  
Resonance Effects

scholarly journals XPS Analysis of 2- and 3-Aminothiophenol Grafted on Silicon (111) Hydride Surfaces

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2712 ◽  
Author(s):  
Chieh-Hua Lee ◽  
Wan-Cian Chen ◽  
Yit Khung
Keyword(s):  
High Resolution ◽  
Nucleophilic Addition ◽  
Surface Reaction ◽  
Negative Charge ◽  
Strong Preference ◽  
Xps Analysis ◽  
Silicon Hydride ◽  
Resonance Structures ◽  
Resonance Effects ◽  
Sh Group

Following on from our previous study on the resonance/inductive structures of ethynylaniline, this report examines similar effects arising from resonance structures with aromatic aminothiophenol with dual electron-donating substituents. In brief, 2- and 3-aminothiophenol were thermally grafted on silicon (111) hydride substrate at 130 °C under nonpolar aprotic mesitylene. From the examination of high resolution XPS Si2p, N1s, and S2p spectrum, it was noticed that there was a strong preference of NH2 over SH to form Si–N linkage on the silicon hydride surface for 2-aminothiophenol. However, for 3-aminothiophenol, there was a switch in reactivity of the silicon hydride toward SH group. This was attributed to the antagonistic and cooperative resonance effects for 2- and 3-aminothiophenol, respectively. The data strongly suggested that the net resonance of the benzylic-based compound could have played an important role in the net distribution of negative charge along the benzylic framework and subsequently influenced the outcome of the surface reaction. To the best of the authors’ knowledge, this correlation between dual electron-donating substituents and the outcome of the nucleophilic addition toward silicon hydride surfaces has not been described before in literature.

Applications of high-resolution 13C and 15N n.m.r. of solids

1981 ◽  
Vol 299 (1452) ◽  
pp. 593-608 ◽  
Keyword(s):  
High Resolution ◽  
Spin Diffusion ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Spatial Proximity ◽  
Magic Angle ◽  
Rotating Frame ◽  
Cross Polarization ◽  
Relaxation Rates ◽  
Relaxation Parameters

The combination of cross polarization, dipolar decoupling and magic angle spinning results in liquid-like high-resolution 13 C and 15 N n.m.r. spectra of a wide variety of solid materials. Structural determinations based on such 13 C n.m.r. spectra include the measurement of the extent to which pyrolysed polyacrylonitrile fibres (Orion) retain aliphatic character during the first step of the production of a carbon fibre, the determination of the chemical identity of the cross links formed from an acetyleneterminated polyimide resin, and the characterization of the metabolic products of a bacterial fermentation of wood lignin. All of these non-destructive analyses are performed on intact heterogeneous samples. The high resolution of the carbon experiment can also be exploited by obtaining proton spin-lattice relaxation parameters for chemically different protons in solids. Because of spin diffusion, these parameters are dependent on spatial proximity and so are helpful in measuring the homogeneity of solid blends of polymers such as poly(phenylene oxide) and polystyrene. High-resolution 13 C n.m.r. spectra of polymers can also be used for measuring microscopic chain dynamics. 13 C rotating-frame relaxation parameters observed for polycarbonate and poly (ethylene terephthalate) are related to the effects on motion of annealing, additives and structural substitutions. Individual relaxation rates are observed for individual carbons, so the behaviour of side groups is cleanly separated from that of the main chain. All of the line-narrowing and sensitivity-enhancing techniques applied to 13 C n.m.r. of solids work equally well for 15 N n.m.r. Use of 15 N rotating-frame and cross-polarization parameters leads to the assessment of the relative concentrations of 13 C - 15 N and 12 C - 15 N pair concentrations in the main chains of multiply labelled proteins. Such measurements can be used to characterize the rate of protein turnover in fully expanded soybean leaves, as well as the details of protein synthesis in cultured soybean cotyledons.

scholarly journals Toroid Cavity Detectors for High-Resolution NMR Spectroscopy and Rotating Frame Imaging: Capabilities and Limitations

2000 ◽  
Vol 142 (2) ◽  
pp. 348-357 ◽  
Author(s):  
Konstantin I Momot ◽  
Nader Binesh ◽  
Olaf Kohlmann ◽  
Charles S Johnson
Keyword(s):  
Nmr Spectroscopy ◽  
High Resolution ◽  
Rotating Frame ◽  
High Resolution Nmr

scholarly journals SRSDD-v1.0: A High-Resolution SAR Rotation Ship Detection Dataset

2021 ◽  
Vol 13 (24) ◽  
pp. 5104
Author(s):  
Songlin Lei ◽  
Dongdong Lu ◽  
Xiaolan Qiu ◽  
Chibiao Ding
Keyword(s):  
Deep Learning ◽  
High Resolution ◽  
Multiple Scales ◽  
State Of The Art ◽  
Rotating Frame ◽  
Ship Detection ◽  
Complex Background ◽  
Complex Scenes ◽  
Small Targets ◽  
Port Areas

Deep learning has been widely used in the field of SAR ship detection. However, current SAR ship detection still faces many challenges, such as complex scenes, multiple scales, and small targets. In order to promote the solution to the above problems, this article releases a high-resolution SAR ship detection dataset which can be used for rotating frame target detection. The dataset contains six categories of ships. In total, 30 panoramic SAR tiles of the Chinese Gaofen-3 of port areas with a 1-m resolution were cropped to slices, each with 1024 × 1024 pixels. In addition, most of the images in the dataset contain nearshore areas with complex background interference. Eight state-of-the-art rotated detectors and a CFAR-based method were used to evaluate the dataset. Experimental results revealed that the complex background will have a great impact on the performance of detectors.

Observations of the spatial structure of interstellar hydrogen

1967 ◽  
Vol 31 ◽  
pp. 45-46
Author(s):  
Carl Heiles
Keyword(s):  
High Resolution ◽  
Spatial Structure ◽  
Velocity Dispersion ◽  
Temperature Variations

High-resolution 21-cm line observations in a region aroundlII= 120°,b11= +15°, have revealed four types of structure in the interstellar hydrogen: a smooth background, large sheets of density 2 atoms cm-3, clouds occurring mostly in groups, and ‘Cloudlets’ of a few solar masses and a few parsecs in size; the velocity dispersion in the Cloudlets is only 1 km/sec. Strong temperature variations in the gas are in evidence.

Combining integrated systems-biology approaches with intervention-based experimental design provides a higher-resolution path forward for microbiome research

2019 ◽  
Vol 42 ◽  
Author(s):  
J. Alfredo Blakeley-Ruiz ◽  
Carlee S. McClintock ◽  
Ralph Lydic ◽  
Helen A. Baghdoyan ◽  
James J. Choo ◽  
...  
Keyword(s):  
Systems Biology ◽  
High Resolution ◽  
Experimental Design ◽  
Integrated Systems ◽  
Microbiome Research ◽  
Constructive Criticism

Abstract The Hooks et al. review of microbiota-gut-brain (MGB) literature provides a constructive criticism of the general approaches encompassing MGB research. This commentary extends their review by: (a) highlighting capabilities of advanced systems-biology “-omics” techniques for microbiome research and (b) recommending that combining these high-resolution techniques with intervention-based experimental design may be the path forward for future MGB research.

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

1994 ◽  
Vol 144 ◽  
pp. 593-596
Author(s):  
O. Bouchard ◽  
S. Koutchmy ◽  
L. November ◽  
J.-C. Vial ◽  
J. B. Zirker
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Field Of View ◽  
Small Field ◽  
High Resolution Analysis ◽  
Ccd Observations ◽  
Resolution Analysis ◽  
Very High ◽  
Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

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