scholarly journals Nuclear magnetic resonance on $LaFeAsO_{0.4}H_{0.6}$ at 3.7 GPa

2019 ◽  
Vol 11 ◽  
pp. 110002
Author(s):  
Naoki Fujiwara ◽  
Masayuki Takeuchi ◽  
T. Kuwayama ◽  
S. Nakagawa ◽  
Soshi Iimura ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Properties ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Low Temperatures ◽  
Nmr Spectra ◽  
Spin Excitations ◽  
Iron Based ◽  
Spin Moments ◽  
Ordered State

A prototypical electron-doped iron-based superconductor $LaFeAsO_{1-x}H_x$ undergoes an antiferromagnetic (AF) phase for $x  \geq 0.49$. We performed NMR measurements on $LaFeAsO_{0.4}H_{0.6}$ at 3.7 GPa to investigate the magnetic properties in the vicinity of a pressure-induced QCP. The linewidth of $~^1H$-NMR spectra broadens at low temperatures below 30 K, suggesting that the ordered spin moments remain at 3.7 GPa. The coexistence of gapped and gapless spin excitations was confirmed in the ordered state from the relaxation time $T_1$ of $~^{75}As$. The pressure-induced QCP is estimated to be 4.1 GPa from the pressure dependence of the gapped excitation.

The Induced Anisotropy and its Influence on Absorption of the NMR and Domain Structure of Со-Р Amorphous Films

2010 ◽  
Vol 168-169 ◽  
pp. 145-148 ◽  
Author(s):  
A. V. Chzhan ◽  
G.S. Patrin ◽  
S.Y. Kiparisov ◽  
V. A. Seredkin ◽  
V.K. Maltsev ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Properties ◽  
Magnetic Resonance ◽  
Experimental Research ◽  
Nmr Spectra ◽  
Induced Anisotropy ◽  
Amorphous Films ◽  
Domain Structures ◽  
Intermediate Layers ◽  
Magnetization Processes

The results of experimental research into magnetic properties of amorphous Co-P films obtained by chemical sedimentation on various intermediate layers have been represented. The nuclear magnetic resonance (NMR) spectra of films sedimentated on intermediate layers of Pd crystal and amorphous NiP compound have been measured .The features of formation of domain structures and magnetization processes in the presence and absence of the induced anisotropy have been described.

NMR study under pressure on the iron-based superconductor FeSe1−xSx (x = 0.12 and 0.23): Relationship between nematicity and AF fluctuations

2020 ◽  
Vol 34 (19n20) ◽  
pp. 2040048
Author(s):  
T. Kuwayama ◽  
K. Matsuura ◽  
Y. Mizukami ◽  
S. Kasahara ◽  
Y. Matsuda ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Nmr Study ◽  
Iron Based ◽  
Nuclear Magnetic

We performed [Formula: see text]-nuclear magnetic resonance measurements on [Formula: see text] ([Formula: see text] = 0.12 and 0.23). We found from the relaxation time [Formula: see text] that nematicity and antiferromagnetic fluctuations show cooperative coupling.

scholarly journals P052 Nuclear magnetic resonance metabolomic profiling of IBD patients under anti-TNF treatment. Are the pathways network deregulated?

2020 ◽  
Vol 14 (Supplement_1) ◽  
pp. S160-S160
Author(s):  
S Notararigo ◽  
M Martin-Pastor ◽  
J E Dominguez Munoz ◽  
M Barreiro-de Acosta
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Mononuclear Cells ◽  
High Rate ◽  
Resonance Spectroscopy ◽  
Serum Samples ◽  
Spectral Window ◽  
Metabolomic Study ◽  
Nuclear Magnetic

Abstract Background The deregulation of immune system cell response implies loss of T-cell apoptosis, high rate of proinflammatory cytokines production and subsequent exacerbate activation of TNF-α pathway. The use of biologic antibody decrease inflammation rate and symptoms, but it remains unclear if it has a direct effect on the pathways activation/inactivation on peripheral blood mononuclear cells (PBMCs). The aim of this study is evaluate the role of nuclear magnetic resonance spectroscopy (NMR) applied to the metabolomic study of serum samples isolated from fresh blood from inflammatory bowel disease (IBD) patients under IFX treatment to understand the activated/inactivated pathways of PBMCs. Methods A case–control study was performed. Inclusion criteria were IBD patients under IFX treatment. Blood samples were obtained in Crohn’s disease (CD) and ulcerative colitis (UC) patients before IFX and in healthy controls (CTRL). CD patients were divided into subgroups according to the gut affected, in Ileocolic (IC), ileum and colon. NMR samples of the serum were collected and measured according to Standard Operation Procedures. Three types of NMR spectra were measured for each serum sample (1Hnoepresat, 1Hcpmgpresat and 1HDfilterpresat). The signal in each NMR spectrum was integrated in a series of equidistant little portion of the spectrum called buckets of a constant width of 0.04 ppm, covering the complete 1H NMR spectral window from −5 to 14 ppm. Buckets in regions depleted from signal at the two extremes of the spectrum were discarded as well as those in the proximity of the water peak at ca. 4.7 ppm which was affected by the presaturation. The vectors corresponding to a number of samples of two or more groups can be rapidly analysed using Multivariant Statistical Analysis methods. Results Twenty-two IBD patients (12 CD and nine UC) were included, 10 CTRL were also included. The metabolomic analyses of the NMR spectra of the serum of the different patients and control groups by the fingerprinting and targeting profiling strategies provided OPLS-DA statistical models (Figure 1) that permitted the successful classification of certain groups of samples which are summarised in Table 1. Conclusion The results of this pilot NMR metabolomic study of serum samples of IBD found a series of spectral fingerprints that are able to discriminate between groups of patients CTRL and CD, which underlines its potential use for the diagnosis of the disease.

The metal nuclear magnetic resonance spectra of some tin(II) and lead(II) complexes with polydentate phosphines

1983 ◽  
Vol 61 (8) ◽  
pp. 1795-1799 ◽  
Author(s):  
Philip A. W. Dean
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Narrow Range ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The previously reported 1:1 complexes formed in MeNO2, between M(SbF6)2 (M = Sn or Pb) and Ph2P(CH2)2PPh2, PhP[(CH2)2PPh2]2, MeC(CH2PPh2)3, P[(CH2)2PPh2]3, and [Formula: see text] have been studied by metal (119Sn or 207Pb) nmr. The metal chemical shifts span the comparatively narrow range of −586 to −792 ppm and 60 to −269 ppm, relative to the resonance of MMe4, for 119Sn and 207Pb nmr, respectively. The implications of these data regarding the denticity of the ligand in M(P[(CH2)2PPh2]3)2+ are discussed, and a comparison with the metal nmr spectra of related stannous and plumbous complexes is made.

Textural and pore size analysis of carbonates from integrated core and nuclear magnetic resonance logging: An Arbuckle study

2015 ◽  
Vol 3 (1) ◽  
pp. SA77-SA89 ◽  
Author(s):  
John Doveton ◽  
Lynn Watney
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Pore Size ◽  
Relaxation Times ◽  
T2 Relaxation Time ◽  
T2 Relaxation ◽  
Nmr Logging ◽  
The Core ◽  
Nuclear Magnetic

The T2 relaxation times recorded by nuclear magnetic resonance (NMR) logging are measures of the ratio of the internal surface area to volume of the formation pore system. Although standard porosity logs are restricted to estimating the volume, the NMR log partitions the pore space as a spectrum of pore sizes. These logs have great potential to elucidate carbonate sequences, which can have single, double, or triple porosity systems and whose pores have a wide variety of sizes and shapes. Continuous coring and NMR logging was made of the Cambro-Ordovician Arbuckle saline aquifer in a proposed CO2 injection well in southern Kansas. The large data set gave a rare opportunity to compare the core textural descriptions to NMR T2 relaxation time signatures over an extensive interval. Geochemical logs provided useful elemental information to assess the potential role of paramagnetic components that affect surface relaxivity. Principal component analysis of the T2 relaxation time subdivided the spectrum into five distinctive pore-size classes. When the T2 distribution was allocated between grainstones, packstones, and mudstones, the interparticle porosity component of the spectrum takes a bimodal form that marks a distinction between grain-supported and mud-supported texture. This discrimination was also reflected by the computed gamma-ray log, which recorded contributions from potassium and thorium and therefore assessed clay content reflected by fast relaxation times. A megaporosity class was equated with T2 relaxation times summed from 1024 to 2048 ms bins, and the volumetric curve compared favorably with variation over a range of vug sizes observed in the core. The complementary link between grain textures and pore textures was fruitful in the development of geomodels that integrates geologic core observations with petrophysical log measurements.

scholarly journals A Metabolomic Approach to Beer Characterization

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1472
Author(s):  
Nicola Cavallini ◽  
Francesco Savorani ◽  
Rasmus Bro ◽  
Marina Cocchi
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Analytical Methods ◽  
Nmr Spectra ◽  
Full Spectrum ◽  
The Past ◽  
Beer Consumption ◽  
Metabolomic Approach ◽  
Chemometric Tools

The consumers’ interest towards beer consumption has been on the rise during the past decade: new approaches and ingredients get tested, expanding the traditional recipe for brewing beer. As a consequence, the field of “beeromics” has also been constantly growing, as well as the demand for quick and exhaustive analytical methods. In this study, we propose a combination of nuclear magnetic resonance (NMR) spectroscopy and chemometrics to characterize beer. 1H-NMR spectra were collected and then analyzed using chemometric tools. An interval-based approach was applied to extract chemical features from the spectra to build a dataset of resolved relative concentrations. One aim of this work was to compare the results obtained using the full spectrum and the resolved approach: with a reasonable amount of time needed to obtain the resolved dataset, we show that the resolved information is comparable with the full spectrum information, but interpretability is greatly improved.

scholarly journals Estimation of the permeability of hydrocarbon reservoir samples using induced polarization and nuclear magnetic resonance methods

Geophysics ◽  
2019 ◽  
Vol 84 (2) ◽  
pp. MR73-MR84 ◽  
Author(s):  
Fatemeh Razavirad ◽  
Myriam Schmutz ◽  
Andrew Binley
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Mechanistic Model ◽  
Transverse Relaxation Time ◽  
Induced Polarization ◽  
Permeability Model ◽  
Transverse Relaxation ◽  
Hydrocarbon Reservoir ◽  
Nuclear Magnetic

We have evaluated several published models using induced polarization (IP) and nuclear magnetic resonance (NMR) measurements for the estimation of permeability of hydrocarbon reservoir samples. IP and NMR measurements were made on 30 samples (clean sands and sandstones) from a Persian Gulf hydrocarbon reservoir. We assessed the applicability of a mechanistic IP-permeability model and an empirical IP-permeability model recently proposed. The mechanistic model results in a broader range of permeability estimates than those measured for sand samples, whereas the empirical model tends to overestimate the permeability of the samples that we tested. We also evaluated an NMR permeability prediction model that is based on porosity [Formula: see text] and the mean of the log transverse relaxation time ([Formula: see text]). This model provides reasonable permeability estimations for the clean sandstones that we tested but relies on calibrated parameters. We also examined an IP-NMR permeability model, which is based on the peak of the transverse relaxation time distribution, [Formula: see text] and the formation factor. This model consistently underestimates the permeability of the samples tested. We also evaluated a new model. This model estimates the permeability using the arithmetic mean of log transverse NMR relaxation time ([Formula: see text]) and diffusion coefficient of the pore fluid. Using this model, we improved estimates of permeability for sandstones and sand samples. This permeability model may offer a practical solution for geophysically derived estimates of permeability in the field, although testing on a larger database of clean granular materials is needed.

scholarly journals Elucidating Tricin-Lignin Structures: Assigning Correlations in HSQC Spectra of Monocot Lignins

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 916 ◽  
Author(s):  
Wu Lan ◽  
Fengxia Yue ◽  
Jorge Rencoret ◽  
José del Río ◽  
Wout Boerjan ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Model Compounds ◽  
Heteronuclear Correlation ◽  
Nmr Methods ◽  
Nuclear Magnetic ◽  
Lignin Structure

Tricin [5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one] is a flavone that has been found to be incorporated in grass lignin polymers via 4′–O–β coupling. Herein, we investigated the tricin-lignin structure using nuclear magnetic resonance (NMR) methods by comparing the 1H–13C heteronuclear correlation (HSQC) NMR spectra of the isolated lignin with a series of dimeric and trimeric tricin-4′–O–β-ether model compounds. Results showed that the tricin moiety significantly affects the chemical shift of the Cβ/Hβ of 4′–O–β unit, producing peaks at around δC/δH 82.5–83.5/4.15–4.45, that differ from the Cβ/Hβ correlations from normal 4–O–β units formed solely by monolignols, and that have to date been unassigned.

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