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Faraday Discussions

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https://read.qxmd.com/read/31120465/complexity-of-dissolved-organic-matter-in-the-molecular-size-dimension-insights-from-coupled-size-exclusion-chromatography-electrospray-ionisation-mass-spectrometry
#1
J A Hawkes, P J R Sjöberg, J Bergquist, L J Tranvik
This paper investigates the relationship between apparent size distribution and molecular complexity of dissolved organic matter from the natural environment. We used a high pressure size exclusion chromatography (HPSEC) method coupled to UV-Vis diode array detection (UV-DAD) and electrospray ionisation mass spectrometry (ESI-MS) in order to compare the apparent size of natural organic matter, determined by HPSEC-UV and the molecular mass determined online by ESI-MS. We found that there was a clear discrepancy between the two methods, and found evidence for an important pool of organic matter that has a strong UV absorbance and no ESI-MS signal...
May 23, 2019: Faraday Discussions
https://read.qxmd.com/read/31120463/joint-and-unique-multiblock-analysis-of-biological-data-multiomics-malaria-study
#2
Izabella Surowiec, Tomas Skotare, Rickard Sjögren, Sandra Gouveia-Figueira, Judy Orikiiriza, Sven Bergström, Johan Normark, Johan Trygg
Modern profiling technologies enable us to obtain large amounts of data which can be used later for a comprehensive understanding of the studied system. Proper evaluation of such data is challenging, and cannot be carried out by bare analysis of separate data sets. Integrated approaches are necessary, because only data integration allows us to find correlation trends common for all studied data sets and reveal hidden structures not known a priori. This improves the understanding and interpretation of complex systems...
May 23, 2019: Faraday Discussions
https://read.qxmd.com/read/31120051/characterising-polar-compounds-using-supercritical-fluid-chromatography-nuclear-magnetic-resonance-spectroscopy-sfc-nmr
#3
F H M van Zelst, S G J van Meerten, A P M Kentgens
To detect and characterise compounds in complex matrices, it is often necessary to separate the compound of interest from the matrix before analysis. In our previous work, we have developed the coupling of supercritical fluid chromatography (SFC) with nuclear magnetic resonance (NMR) spectroscopy for the analysis of nonpolar samples [Van Zelst et al., Anal. Chem., 2018, 90, 10457]. In this work, the SFC-NMR setup was successfully adapted to analyse polar samples in complex matrices. In-line SFC-NMR analysis of two N-acetylhexosamine stereoisomers was demonstrated, namely N-acetyl-mannosamine (ManNAc) and N-acetyl-glucosamine (GlcNAc)...
May 23, 2019: Faraday Discussions
https://read.qxmd.com/read/31120050/deciphering-complex-metabolite-mixtures-by-unsupervised-and-supervised-substructure-discovery-and-semi-automated-annotation-from-ms-ms-spectra
#4
Simon Rogers, Cher Wei Ong, Joe Wandy, Madeleine Ernst, Lars Ridder, Justin J J van der Hooft
Complex metabolite mixtures are challenging to unravel. Mass spectrometry (MS) is a widely used and sensitive technique for obtaining structural information of complex mixtures. However, just knowing the molecular masses of the mixture's constituents is almost always insufficient for confident assignment of the associated chemical structures. Structural information can be augmented through MS fragmentation experiments whereby detected metabolites are fragmented, giving rise to MS/MS spectra. However, how can we maximize the structural information we gain from fragmentation spectra? We recently proposed a substructure-based strategy to enhance metabolite annotation for complex mixtures by considering metabolites as the sum of (bio)chemically relevant moieties that we can detect through mass spectrometry fragmentation approaches...
May 23, 2019: Faraday Discussions
https://read.qxmd.com/read/31120047/collection-and-identification-of-an-unknown-component-from-eugenia-uniflora-essential-oil-exploiting-a-multidimensional-preparative-three-gc-system-employing-apolar-mid-polar-and-ionic-liquid-stationary-phases
#5
Danilo Sciarrone, Antonino Schepis, Gemma De Grazia, Archimede Rotondo, Filippo Alibrando, Roger Raupp Cipriano, Humberto Bizzo, Cicero Deschamps, Leonard M Sidisky, Luigi Mondello
The present research deals with the collection and structural elucidation of an unknown component, accounting for about 35% of the essential oil obtained upon distillation of the leaves of Eugenia uniflora L., harvested during summer (January, 2017) in Paraná State (Southern Brazil). A multidimensional gas chromatographic preparative system, based on the coupling of three GC systems equipped with apolar, PEG and ionic liquid-based stationary phases, was successfully applied for the isolation of the chromatographic band relative to the unknown molecule...
May 23, 2019: Faraday Discussions
https://read.qxmd.com/read/31120046/structural-analysis-of-heavy-oil-fractions-after-hydrodenitrogenation-by-high-resolution-tandem-mass-spectrometry-and-ion-mobility-spectrometry
#6
Johann Le Maître, Marie Hubert-Roux, Benoît Paupy, Sabrina Marceau, Christopher P Rüger, Carlos Afonso, Pierre Giusti
Heavy petroleum fractions such as vacuum gas oils (VGOs) are structurally and compositionally highly complex mixtures. Nitrogen species, which have a significant impact on the subsequent refining processes, are generally removed by the hydrodenitrogenation (HDN) catalytic process. The purpose of this study was to identify and characterize compounds that are refractory to the HDN process. This may allow for the examination of the effectiveness of a vacuum distillate hydrotreatment catalytic bed in removing nitrogen-containing compounds before the cracking step...
May 23, 2019: Faraday Discussions
https://read.qxmd.com/read/31120045/automatised-pharmacophoric-deconvolution-of-plant-extracts-application-to-cinchona-bark-crude-extract
#7
Laure Margueritte, Laura Duciel, Mélanie Bourjot, Catherine Vonthron-Sénécheau, Marc-André Delsuc
We present a development of the "Plasmodesma" dereplication method [Margueritte et al., Magn. Reson. Chem., 2018, 56, 469]. This method is based on the automatic acquisition of a standard set of NMR experiments from a medium sized set of samples differing by their bioactivity. From this raw data, an analysis pipeline is run and the data is analysed by leveraging machine learning approaches in order to extract the spectral fingerprints of the active compounds. The optimal conditions for the analysis are determined and tested on two different systems, a synthetic sample where a single active molecule is to be isolated and characterized, and a complex bioactive matrix with synergetic interactions between the components...
May 23, 2019: Faraday Discussions
https://read.qxmd.com/read/31119225/unraveling-the-complexity-of-complex-mixtures-by-combining-high-resolution-pharmacological-analytical-and-spectroscopic-techniques-antidiabetic-constituents-in-chinese-medicinal-plants
#8
Yong Zhao, Kenneth Thermann Kongstad, Yueqiu Liu, Chenghua He, Dan Staerk
Medicinal plants have been widely used as (poly)pharmacological remedies and constitute a rich source for antidiabetic drug discovery. In the present study, forty medicinal plant samples collected in China were tested for inhibitory activity against α-glucosidase, α-amylase, and protein-tyrosine phosphatase 1B (PTP1B). Crude ethyl acetate extracts of Dioscorea bulbifera L., Boehmeria nivea Gaudich, Tinospora sagittata Gagnep. and Persicaria bistorta (L.) Samp. showed dual inhibitory activity towards α-glucosidase and PTP1B, and were chosen for further investigation...
May 23, 2019: Faraday Discussions
https://read.qxmd.com/read/31116193/application-of-novel-solid-phase-extraction-nmr-protocols-for-metabolic-profiling-of-human-urine
#9
Daniel McGill, Elena Chekmeneva, John C Lindon, Zoltan Takats, Jeremy K Nicholson
Metabolite identification and annotation procedures are necessary for the discovery of biomarkers indicative of phenotypes or disease states, but these processes can be bottlenecked by the sheer complexity of biofluids containing thousands of different compounds. Here we describe low-cost novel SPE-NMR protocols utilising different cartridges and conditions, on both natural and artificial urine mixtures, which produce unique retention profiles useful for metabolic profiling. We find that different SPE methods applied to biofluids such as urine can be used to selectively retain metabolites based on compound taxonomy or other key functional groups, reducing peak overlap through concentration and fractionation of unknowns and hence promising greater control over the metabolite annotation/identification process...
May 22, 2019: Faraday Discussions
https://read.qxmd.com/read/31115412/structural-investigation-of-coal-humic-substances-by-selective-isotopic-exchange-and-high-resolution-mass-spectrometry
#10
Alexander Zherebker, Irina V Perminova, Yury Kostyukevich, Alexey S Kononikhin, Oleg Kharybin, Eugene Nikolaev
Here, we report the application of a selective liquid-phase hydrogen/deuterium exchange (HDX) coupled to ultra-high resolution FTICR MS for structural investigations of individual constituents of humic substances (HS) isolated from three coal samples of different geographical origin. Selectivity was achieved by conducting reactions in DCl or NaOD solutions for catalyzing HDX in aromatic ring and side-chain positions with enhanced C-H acidity, respectively. FTICR MS analysis showed a significant overlap of molecular compositions in the HS samples under study, with 2000 common formulae...
May 22, 2019: Faraday Discussions
https://read.qxmd.com/read/31115392/probing-the-selectivity-of-li-and-na-cations-on-noradrenaline-at-the-molecular-level
#11
Shun-Ichi Ishiuchi, Hiromichi Wako, Sotiris S Xantheas, Masaaki Fujii
Although several mechanisms concerning the biological function of lithium salts, drugs having tranquilizing abilities, have been proposed so far, the key mechanism for its selectivity and subsequent interaction with neurotransmitters has not been established yet. We report ultraviolet (UV) and infrared (IR) spectra under ultra-cold conditions of Li+ and Na+ complexes of noradrenaline (NAd, norepinephrine), a neurotransmitter responsible for the body's response to stress or danger, in an effort to provide a molecular level understanding of the conformational changes of NAd due to its interactions with these two cations...
May 22, 2019: Faraday Discussions
https://read.qxmd.com/read/31114838/resolving-complex-hierarchies-in-chemical-mixtures-how-chemometrics-may-serve-in-understanding-the-immune-system
#12
Gerjen Herman Tinnevelt, Jeroen Jasper Jansen
In immunology, the resolution of complex chemical mixtures familiar from omics, comes with an added layer of hierarchy: bioactive immunological surface markers are embedded on the cell membranes of e.g. white blood cells. Therefore, each blood sample actually consists of a comprehensive mixture of cells. The cells need to be resolved based on their surface marker chemistry, to investigate their involvement in an immune response. This mixture may be measured on a single-cell level with Multicolour Flow Cytometry (MFC)...
May 22, 2019: Faraday Discussions
https://read.qxmd.com/read/31114816/focusing-on-the-important-through-targeted-nmr-experiments-an-example-of-selective-13-c-12-c-bond-detection-in-complex-mixtures
#13
Amy Jenne, Ronald Soong, Wolfgang Bermel, Nisha Sharma, Antonio Masi, Maryam Tabatabaei Anaraki, Andre Simpson
Current research is attempting to address more complex questions than ever before. As such, the need to follow complex processes in intact media and mixtures is becoming commonplace. Here, a targeted NMR experiment is introduced which selectively detects the formation of 13C-12C bonds in mixtures. This study introduces the experiment on simple standards, and then demonstrates the potential on increasingly complex processes including: fermentation, Arabidopsis thaliana germination/early growth, and metabolism in Daphnia magna both ex vivo and in vivo...
May 22, 2019: Faraday Discussions
https://read.qxmd.com/read/31114813/an-integrated-approach-for-mixture-analysis-using-ms-and-nmr-techniques
#14
Stefan Kuhn, Simon Colreavy-Donnelly, Juliana Santana de Souza, Ricardo Moreira Borges
We suggest an improved software pipeline for mixture analysis. The improvements include combining tandem MS and 2D NMR data for a reliable identification of the constituents in an algorithm based on network analysis aiming for a robust and reliable identification routine. An important part of this pipeline is the use of open-data repositories, although it is not totally reliant on them. The NMR identification step emphasizes robustness and is less sensitive towards changes in data acquisition and processing than existing methods...
May 22, 2019: Faraday Discussions
https://read.qxmd.com/read/31112190/ultrafast-photoinduced-energy-and-charge-transfer
#15
Majed Chergui
After presenting the basic theoretical models of excitation energy transfer and charge transfer, I describe some of the novel experimental methods used to probe them. Finally, I discuss recent results concerning ultrafast energy and charge transfer in biological systems, in chemical systems and in photovoltaics based on sensitized transition metal oxides.
May 21, 2019: Faraday Discussions
https://read.qxmd.com/read/31112152/polar-mixture-analysis-by-nmr-under-spin-diffusion-conditions-in-viscous-sucrose-solution-and-agarose-gel
#16
Pedro Lameiras, Simon Mougeolle, François Pedinielli, Jean-Marc Nuzillard
The use of two new viscous solvents, sucrose solution and agarose gel, is reported for the first time for giving access to the individual NMR spectra of polar and potentially bioactive compounds in a mixture. Under viscous conditions, the tumbling rate of small and mid-sized molecules reduces in solution, so that the longitudinal cross-relaxation encourages the observation of spin diffusion. As a result, all of the resonances of the 1H nuclei within the same molecule tend to correlate together in a 2D NOESY spectrum, thus paving the way to mixture analysis...
May 21, 2019: Faraday Discussions
https://read.qxmd.com/read/31111128/ion-reactions-in-atmospherically-relevant-clusters-mechanisms-dynamics-and-spectroscopic-signatures
#17
Natalia V Karimova, Laura M McCaslin, R Benny Gerber
Reactions of nitrogen oxides with seawater are of major atmospheric importance, but microscopic understanding of these processes is still largely unavailable. In this paper we explore models of reactions of N2O4 with ions in water in order to provide molecular-level understanding of the processes. Presented here are studies of N2O4 interacting with two ions, SO42- and Cl-, in small water clusters. Reactions of the asymmetric conformer of N2O4 with SO42- ions in water clusters are studied via ab initio molecular dynamics (AIMD) simulations in order to unravel the microscopic mechanism of the processes and predict the timescales of different steps...
May 21, 2019: Faraday Discussions
https://read.qxmd.com/read/31095152/theory-of-hot-electrons-general-discussion
#18
Javier Aizpurua, Francesca Baletto, Jeremy Baumberg, Phillip Christopher, Bart de Nijs, Preeti Deshpande, Yuri Diaz Fernandez, Laura Fabris, Simon Freakley, Sylwester Gawinkowski, Alexander Govorov, Naomi Halas, Romain Hernandez, Bartlomiej Jankiewicz, Jacob Khurgin, Mikael Kuisma, Priyank Vijaya Kumar, Johannes Lischner, Jie Liu, Andrea Marini, Reinhard J Maurer, Niclas Sven Mueller, Matteo Parente, Jeong Y Park, Stephanie Reich, Yonatan Sivan, Giulia Tagliabue, Laura Torrente-Murciano, Madasamy Thangamuthu, Xiaofei Xiao, Anatoly Zayats
No abstract text is available yet for this article.
May 16, 2019: Faraday Discussions
https://read.qxmd.com/read/31094389/dynamics-of-hot-electron-generation-in-metallic-nanostructures-general-discussion
#19
Javier Aizpurua, Michael Ashfold, Francesca Baletto, Jeremy Baumberg, Phillip Christopher, Emiliano Cortés, Bart de Nijs, Yuri Diaz Fernandez, Julian Gargiulo, Sylwester Gawinkowski, Naomi Halas, Ruben Hamans, Bartlomiej Jankiewicz, Jacob Khurgin, Priyank Vijaya Kumar, Jie Liu, Stefan Maier, Reinhard J Maurer, A Mount, Niclas Sven Mueller, Rupert Oulton, Matteo Parente, Jeong Y Park, John Polanyi, Jhon Quiroz, Sebastian Rejman, Sebastian Schlücker, Zachary Schultz, Yonatan Sivan, Giulia Tagliabue, Madasamy Thangamuthu, Laura Torrente-Murciano, Xiaofei Xiao, Anatoly Zayats, Chao Zhan
No abstract text is available yet for this article.
May 16, 2019: Faraday Discussions
https://read.qxmd.com/read/31094388/introductory-lecture-advances-in-ion-spectroscopy-from-astrophysics-to-biology
#20
Helen J Zeng, Nan Yang, Mark A Johnson
This introduction provides a historical context for the development of ion spectroscopy over the past half century by following the evolution of experimental methods to the present state-of-the-art. Rather than attempt a comprehensive review, we focus on how early work on small ions, carried out with fluorescence, direct absorption, and photoelectron spectroscopy, evolved into powerful technologies that can now address complex chemical problems ranging from catalysis to biophysics. One of these developments is the incorporation of cooling and temperature control to enable the general application of "messenger tagging" vibrational spectroscopy, first carried out using ionized supersonic jets and then with buffer gas cooling in radiofrequency ion traps...
May 16, 2019: Faraday Discussions
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