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Magnetic Resonance in Chemistry: MRC

Laura Castañar
No abstract text is available yet for this article.
October 19, 2016: Magnetic Resonance in Chemistry: MRC
Maria Baias
What is "cultural heritage"? Is it simply our legacy of physical artifacts - or is it our collective legacy as human societies - how we want to be remembered by future generations? With time, negligence, and even military conflict working to erase the past, we must ask: Can a better understanding of our shared heritage assist us in addressing cultural differences in the present day? And how can science both help us understand the historic record and work to preserve it? In this perspective article we examine an emerging scientific method, mobile nuclear magnetic resonance, that can help us examine in a non-invasive way important objects and sites of our cultural heritage...
October 17, 2016: Magnetic Resonance in Chemistry: MRC
Volker Schmidts
No abstract text is available yet for this article.
October 15, 2016: Magnetic Resonance in Chemistry: MRC
Patrick Giraudeau, Roberto R Gil
No abstract text is available yet for this article.
October 15, 2016: Magnetic Resonance in Chemistry: MRC
Clark D Ridge, Eugene P Mazzola, Martyn P Coles, Simon F R Hinkley
The commonly occurring, high-cytotoxicity macrolide roridin E has been re-isolated from Stachybotrys atra and characterized by 1- and 2-D NMR spectroscopy. Assignment of the spectral data for roridin E revealed differences from the accepted literature, and spectra are reported herein to aid in future identification. For the first time confirmation of structure was provided by a crystallographic solution for roridin E.
October 13, 2016: Magnetic Resonance in Chemistry: MRC
André Fonseca, Alexandra Gaspar, Maria João Matos, Ligia R Gomes, John N Low, Eugenio Uriarte, Fernanda Borges
No abstract text is available yet for this article.
October 12, 2016: Magnetic Resonance in Chemistry: MRC
Susanna Ahola, Otto Mankinen, Ville-Veikko Telkki
Standard diffusion NMR measurements require the repetition of the experiment multiple times with varying gradient strength or diffusion delay. This makes the experiment time-consuming and restricts the use of hyperpolarized substances to boost sensitivity. We propose a novel single-scan diffusion experiment, which is based on spatial encoding of two-dimensional data, employing the spin-echoes created by two successive adiabatic frequency-swept chirp π pulses. The experiment is called ultrafast pulsed-field-gradient spin-echo (UF-PGSE)...
October 11, 2016: Magnetic Resonance in Chemistry: MRC
Anna L Dunn, Clark R Landis
A stopped-flow NMR probe is described that enables fast flow rates, short transfer times, and equilibration of the reactant magnetization and temperature prior to reaction. The capabilities of the probe are demonstrated by monitoring the polymerization of lactide as catalyzed by the air-sensitive catalyst 1,3-dimesitylimidazol-2-ylidene (IMes) over the temperature range of -30 to 40 °C. The incorporation of stopped-flow capabilities into an NMR probe permits the rich information content of NMR to be accessed during the first few seconds of a fast reaction...
October 8, 2016: Magnetic Resonance in Chemistry: MRC
Biljana Arsic, Juan A Aguilar, Richard A Bryce, Jill Barber
No abstract text is available yet for this article.
October 6, 2016: Magnetic Resonance in Chemistry: MRC
Mike Kline, Dawn Pierce, Steve Cheatham
No abstract text is available yet for this article.
October 5, 2016: Magnetic Resonance in Chemistry: MRC
Beom Soo Kim, Eun Jee Koh, Yearam Jung, Soon Young Shin, Yoongho Lim
No abstract text is available yet for this article.
September 28, 2016: Magnetic Resonance in Chemistry: MRC
Guilherme Dal Poggetto, Victor U Antunes, Mathias Nilsson, Gareth A Morris, Cláudio F Tormena
NMR is the most versatile tool for the analysis of organic compounds and, in combination with DOSY ("Diffusion-Ordered Spectroscopy"), can give information on compounds in complex mixtures without the need for physical separation. In mixtures where the components' diffusion coefficients are nearly identical, for example due to similar sizes, MAD ("Matrix-Assisted DOSY") can help separate the signals of different constituents, resolving their spectra. Unfortunately, DOSY (including MAD) typically fails where signals overlap, as is common in (1) H NMR...
September 28, 2016: Magnetic Resonance in Chemistry: MRC
Julien Wist
Untargeted strategies have changed the rules of the game in complex mixture analysis, introducing an amazing potential for medical and biological applications that is just starting to be tapped. But with great power come great challenges; although untargeted mixture analysis opens the road for many exciting possibilities, the road is still full of perils. On the one hand, this article highlights some of the difficulties that need to be sorted for mixture analysis by NMR to fulfill its potential, along with insight on how they may be managed...
September 26, 2016: Magnetic Resonance in Chemistry: MRC
I Z Rakhmatullin, L F Galiullina, A A Balandina, M R Garipov, A D Strelnik, A S Galiullina, Y G Shtyrlin, V V Klochkov
The conformational properties of three pyridoxine derivatives were studied by (1) H dynamic NMR spectroscopy. Conformational exchange caused by a rotation of 2-nytrophenyl group around one single C-C bond, of 2,4-dinitrophenyl substituent around two single C-O bonds, and twist-twist transformations of the seven-membered ketal cycle was observed by NMR experiments at low temperatures. Meanwhile, the conformational exchange of the acetal ring remains fast in the NMR timescale even at 198 K. The energy barriers for all observed conformational exchange processes were determined by the lineshape analysis of dynamic NMR spectra...
September 23, 2016: Magnetic Resonance in Chemistry: MRC
Sikiru Afolabi Adebileje, Keyvan Ghasemi, Hammed Tanimowo Aiyelabegan, Hamidreza Saligheh Rad
Proton magnetic resonance spectroscopy is a powerful noninvasive technique that complements the structural images of cMRI, which aids biomedical and clinical researches, by identifying and visualizing the compositions of various metabolites within the tissues of interest. However, accurate classification of proton magnetic resonance spectroscopy is still a challenging issue in clinics due to low signal-to-noise ratio, overlapping peaks of metabolites, and the presence of background macromolecules. This paper evaluates the performance of a discriminate dictionary learning classifiers based on projective dictionary pair learning method for brain gliomas proton magnetic resonance spectroscopy spectra classification task, and the result were compared with the sub-dictionary learning methods...
September 23, 2016: Magnetic Resonance in Chemistry: MRC
Luis Pablo Calle, Juan Félix Espinosa
No abstract text is available yet for this article.
September 23, 2016: Magnetic Resonance in Chemistry: MRC
Mikhail Zubkov, Gary R Dennis, Tim Stait-Gardner, Allan M Torres, Scott A Willis, Gang Zheng, William S Price
NMR diffusion measurements (or dNMR) provide a powerful tool for analysis of solution organization and microgeometry of the environment by probing random molecular motion. Being a very versatile method, dNMR can be applied to a large variety of samples and systems. Here, a brief introduction into dNMR and a summary of recent advances in the field are presented. The research topics include restricted diffusion, anisotropic diffusion, polymer dynamics, solution structuring and dNMR method development. The dNMR studied systems include plants, cells (cell models), liquid crystals, polymer solutions, ionic liquids, supercooled solutions, untreated water, amino acid solutions and more...
September 22, 2016: Magnetic Resonance in Chemistry: MRC
Lizheng Zhu, Andrew J Ilott, Eleonora Del Federico, Cindie Kehlet, Torunn Klokkernes, Alexej Jerschow
Reindeer skin clothing has been an essential component in the lives of indigenous people of the arctic and sub-arctic regions, keeping them warm during harsh winters. However, the skin processing technology, which often conveys the history and tradition of the indigenous group, has not been well documented. In this study, NMR spectra and relaxation behaviors of reindeer skin samples treated with a variety of vegetable tannin extracts, oils and fatty substances are studied and compared. With the assistance of principal component analysis (PCA), one can recognize patterns and identify groupings of differently treated samples...
September 21, 2016: Magnetic Resonance in Chemistry: MRC
Damien Jeannerat
The introduction of a universal data format to report the correlation data of 2D NMR spectra such as COSY, HSQC and HMBC spectra will have a large impact on the reliability of structure determination of small organic molecules. These lists of assigned cross peaks will bridge signals found in NMR 1D and 2D spectra and the assigned chemical structure. The record could be very compact, human and computer readable so that it can be included in the supplementary material of publications and easily transferred into databases of scientific literature and chemical compounds...
September 18, 2016: Magnetic Resonance in Chemistry: MRC
José A A França, Armando Navarro-Vázquez, Xinxiang Lei, Han Sun, Christian Griesinger, Fernando Hallwass
The (1) H and (13) C NMR spectra of 17-α-ethinylestradiol (EE2), a well-known contraceptive, including diastereotopic methylene groups, were fully assigned with the help of residual dipolar couplings (RDC) measured in the recently developed grafted graphene oxide orienting medium. RDC analysis, which included all (1) DCH couplings and the long-range (2) DCH(1) H-C≡(13) C coupling, also pointed to the presence of a minor conformation arising from pseudo-rotation of the steroid B ring. Saturation-transfer difference (STD) measurements revealed that the most likely interaction between EE2 and orienting medium occurred on the C and D ring...
September 16, 2016: Magnetic Resonance in Chemistry: MRC
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