Search results for "NMR"

Effect of lithium ions on the catalytic efficiency of calcium oxide as a nanocatalyst for the transesterification of lard oil

2019

The present work encompasses the effect of Li+ ions on CaO nanoparticles for the transesterification of lard oil. The modification of CaO nanoparticles was achieved by the impregnation of different molar ratios of lithium hydroxide. Later, each catalyst was screened for the catalytic conversion of lard oil to a fatty acid methyl ester (FAME). The nanocatalyst CaO–0.5LiOH (1 : 0.5 molar ratio) showed the best conversion rate for FAME. The synthesized nanocatalyst was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, and Hammett indicato…

Aged Nicotinamide Riboside Kinase 2 Deficient Mice Present an Altered Response to Endurance Exercise Training

2018

Background: Skeletal muscle aging is marked by the development of a sarcopenic phenotype, a global decline of muscle energetic capacities, and an intolerance to exercise. Among the metabolic disorders involved in this syndrome, NAD metabolism was shown to be altered in skeletalmuscle, with an important role for the NAMPT enzyme recycling the nicotinamide precursor. An alternative pathway for NAD biosynthesis has been described for the nicotinamide riboside vitamin B3 precursor used by the NMRK kinases, including the striated muscle-specific NMRK2.Aim: With this study, our goal is to explore the ability of 16-month-old Nmrk2−/− mice to perform endurance exercise and study the consequences on…

Supramolecular organization of triglycerides in extra-virgin olive oils as assessed by high and low field NMR spectroscopies

2009

Synthesis and characterization of a novel high luminescent gold-2-mercapto-1-methyl-imidazole complex

2010

Synthesis and characterization of a new gold-2-mercapto-1-methyl imidazole are reported. This new organic material shows an extraordinary fluorescence activity (superfluorescence) up to 220°C with an unusual quantum yield of 0.2. Both fluorescence and NMR spectroscopy were applied to understand the behavior of the gold-2-mercapto-1-methylimidazole complex. Results suggest that the superfluorescence activity can be attributed to the shrinking of the HOMO-LUMO band gap energy following complexation of the organic imidazole system with gold. Copyright © 2010 John Wiley & Sons, Ltd.

High Resolution-magic Angle Spinning NMR Study of Olive Leaves

2013

In recent years HR-MAS 1H NMR spectroscopy has proven to be a useful tool for the rapid determination of the metabolic profile of several solid and semisolid foods, such as fruits and vegetables, cheese and meat. Olive leaves are today recognized as direct sources of bioactive compounds and natural antioxidants (flavonoids, secoiridoids) suitable as food additives, and their extracts form the basis of beauty care products and pharmaceutical supplements. Thus, olive leaves are emerging as a new and potentially important product for olive tree growing regions. In this report we present the application of 1H and 13C HR-MAS 1D and 2D NMR spectroscopy for the characterization and analysis of tri…

Study of the formation of carbonyl compounds in edible oils and fats by 1H-NMR and FTIR

1999

Abstract Oils and fats start decomposing from the moment they are isolated from their natural environment. Heating accelerates oxidative rancidity and frying at high temperatures produces thermal degradation with the formation of decomposition products, such as aldehydes, ketones, free acids and hydroxilic compounds that in high levels can be harmful to human health. The decomposition products formed up to 300°C were determined by means of 1 H-NMR spectroscopy and an FTIR spectroscopic method was developed for the quantification of carbonyl compounds generated during heating. The results show that there is a formation of carbonyl compounds starting at 150°C and when the sample was heated at…

Orientation and molecular contacts of melatonin confined into AOT and lecithin reversed micellar systems

2008

Abstract The state of increasing amounts of melatonin (MLT) confined in dry AOT or lecithin reversed micelles dispersed in CCl 4 has been investigated by UV–vis and 1 H NMR spectroscopies. The experimental results are consistent with MLT totally entrapped in reversed micelles, as a consequence of specific melatonin/surfactant interaction; the main driving force of the MLT solubilization in the core of reversed micelles is the establishment of H-bonding between the MLT NH groups (both indolic and amidic) and the head group of surfactants. The short contacts deduced from intermolecular NOEs are accounted for by favourable interactions between the surfactant's polar head and the H7–NH–H2 fragm…

Physicochemical investigation of acrylamide solubilization in sodium bis(2-ethylhexyl)sulfosuccinate and lecithin reversed micelles.

2003

The state of acrylamide confined within dry sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and lecithin reversed micelles dispersed in CCl4 has been investigated by FTIR and H-1 NMR spectroscopy. Measurements have been performed at 25 degreesC as a function of the acrylamide-to-surfactant molar ratio (R) at a fixed surfactant concentration (0.1 mol kg(-1)). The analysis of experimental data, corroborated by the results of SAXS measurements, is consistent with the hypothesis that acrylamide is quite uniformly distributed among reversed micelles mainly located in proximity to the surfactant head-group region and that its presence induces significant unidimensional growth of micellar aggregates.…

1H NMR-based metabolic profiling for evaluating poppy seed rancidity and brewing

2015

Poppy seeds are widely used in household and commercial confectionery. The aim of this study was to demonstrate the application of metabolic profiling for industrial monitoring of the molecular changes which occur during minced poppy seed rancidity and brewing processes performed on raw seeds. Both forms of poppy seeds were obtained from a confectionery company. Proton nuclear magnetic resonance (1H NMR) was applied as the analytical method of choice together with multivariate statistical data analysis. Metabolic fingerprinting was applied as a bioprocess control tool to monitor rancidity with the trajectory of change and brewing progressions. Low molecular weight compounds were found to be…

Volatile flavour components of ocimum basilicum var. hispidum (lam.) Chiov.

1991

The volatile components obtained by steam-distillation ofOcimum basilicum var. hispidum (Lam.) Chiov. (Labiatae) were analysed by gas chromatography (GC) and gas chromatography—mass spectrometry (GC-MS). A total of 21 compounds, representing ca 90% of the total oil, were identified. The identity of the main component (82%), dihydrotagetone, was confirmed by 1H- and 13C-NMR spectroscopy. This is the first report of this compound in the genus Ocimum.