Search results for " Spectroscopy"

Study of lecithin reverse micelles by FT-IR spectroscopy

2007

FT-IR spectra of water/lecithin/deuterated cyclohexane microemulsions as a function of water/lecithin molar ratio R (R=[water]/[lecithin]) at various lecithin volume fractions (φ) have been recorded. After elimination of the spectral contributions due to the deuterated cyclohexane and normalization, the band parameters of the CO and PO4 vibrational modes due to lecithin have been found dependent only upon R. This behaviour has been interpreted in terms of a progressive structural modification of the water/lecithin interface superimposed to the progressive hydration of CO and PO4 groups. Moreover, no correlation between the CO and PO4 band parameters and the formation of gel-like micellar so…

New 2-Methoxy Acetylenic Acids and Pyrazole Alkaloids from the Marine Sponge Cinachyrella sp.

2017

Three new 2-methoxy acetylenic acids (1–3) and a known derivative (4), in addition to three new natural pyrazole alkaloids (5–7) were isolated from an Indonesian marine sponge of the genus Cinachyrella. Compounds 5 and 6 have previously been reported as synthetic compounds. The structures of the new compounds were established on the basis of one- and two-dimensional NMR spectroscopy as well as by mass spectrometric data. The absolute configuration of the new acetylenic acid derivatives (1–3) was established by ECD spectroscopy. All isolated compounds were evaluated for their cytotoxicity against L5178Y mouse lymphoma cells. Compounds 1–4 exhibited strong activity with an IC50 value of 0.3 µ…

Induction of new metabolites from sponge-associated fungus Aspergillus carneus by OSMAC approach.

2018

Abstract A comparative study on the metabolic profile of the sponge-associated fungus Aspergillus carneus using the OSMAC approach was conducted. The fungal strain was fermented on three different media including solid rice medium with or without sea salt and modified Czapek medium. Three new natural products, isopropylchaetominine (1), isoterrelumamide A (2) and 5′-epi-averufanin (3), together with fourteen known compounds (4–17) were isolated. The structures of the new compounds were established by 1D and 2D NMR spectroscopic analysis as well as by HRESIMS. Compound 2 was only found when the fungus was cultivated on modified Czapek medium, whereas compounds 4, 7, 11, 12, and 14 were only …

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.…

Spectroscopic analyses of the influence of electron beam irradiation doses on mechanical, transport properties and microstructure of chitosan-fish ge…

2015

International audience; The objective of this work was to better display the effect of electron beam accelerator doses (0, 20, 40 and 60 kGy) on structural, mechanical and barrier properties of edible lightly plasticized chitosan-fish gelatin blend film. From Electron Spin Resonance (ESR), signal at 3500 G for blend film was identified as free radical formation during irradiation, which might introduce intermolecular cross-linking into the polymer matrix, thus affecting structural properties. Tensile Strength (TS) for gelatin film significantly increased with growing irradiation doses (improved by 30% for 60 kGy), but the TS of chitosan and blend films were not significantly affected. On th…

Structure of calcium and zinc pectinate films investigated by FTIR spectroscopy

2010

International audience; Calcium and zinc pectinate gels were prepared using a method which allowed calcium or zinc to diffuse from the cross-linking solution through a dialysis membrane to form a gel with amidated low-methoxyl pectin. The gel thus obtained was then dried, and the film structure was studied using FTIR spectroscopy as a function of the cation content (0%, 5%, 10%, and 15% w/v). Important consideration was given to the three functional groups (amide, carboxyl ester, and carboxylate groups) present in the pectin. When the zinc content was increased, the three wavenumber values corresponding to these three functional groups did not change significantly, while for calcium pectina…

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…

Koherentu procesu lāzeru spektroskopijas pētījumi sārmu metālu atomos un molekulās

2014

Promocijas darbs veltīts Zēmana koherenču atomu un molekulu elektroniskajos pamatstāvokļos veidošanas un sabrukšanas teorētiskajai un eksperimentālajai izpētei ar nelineārās spektroskopijas metodēm. Pirmkārt, tiek ziņots polarizācijas modulācijas pētījums, ierosinot D1 pārejas ar Cs tvaikiem pildītā šūnā. Otrkārt, izstrādāta spektroskopijas metode magnētiskā lauka stipruma divdimensiju sadalījuma kartēšanai, izmantojot fluorescences sadalījuma reģistrēšanu. Treškārt, veikts nelineāro magneto-optisko rezonanšu pētījums K2 molekulas pamatstāvoklī ar lielām leņķiskā momenta kvantu skaitļa J~100 vērtībām. Lai uzlabotu diožu lāzera ilgtermiņa frekvences stabilitāti, izstrādāta frekvences divmodu…

The effects of exercising in the cold on energy metabolism, skeletal muscle tissue oxygenation and immuno-endocrine responses

2014

Recoil-decay tagging spectroscopy of 162 74 W 88

2015

Excited states in the highly neutron-deficient nucleus 162W have been investigated via the 92Mo(78Kr, 2α) 162W reaction. Prompt γ rays were detected by the JUROGAM II high-purity germanium detector array and the recoiling fusion-evaporation products were separated by the recoil ion transport unit (RITU) gas-filled recoil separator and identified with the gamma recoil electron alpha tagging (GREAT) spectrometer at the focal plane of RITU. γ rays from 162W were identified uniquely using mother-daughter and mother-daughter-granddaughter α-decay correlations. The observation of a rotational-like ground-state band is interpreted within the framework of total Routhian surface (TRS) calculations, …