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1.
Thomas Glonek 《Journal of the American Oil Chemists' Society》1998,75(5):569-573
Phosphorus-31 nuclear magnetic resonance provides well-dispersed, quantifiable phospholipid profiles of commercial and laboratory
anionic lecithin preparations. Seventeen phospholipids were determined in commercial soybean lecithins. Lecithin refinement
to produce anionic-enriched lecithins may be monitored precisely. 相似文献
2.
Apparent aromaticities of a series of Canadian coals of different rank were estimated by solid state nuclear magnetic resonance spectroscopy. The aromaticities varied from 0.57 for a lignite up to 0.86 for a semi-anthracite coal. The aromaticities correlated well with fixed carbon and oxygen content of the coals as well as with the mean reflectance of the coals. Correlations were also established between aromaticities and the H/C and Haru/Car ratios of the coals. Uncertainties in calculation of the hypothetical Haru/Car ratios, from experimental data were pointed out.Structural parameters of the chars derived from the coals by pyrolysis at 535°C were, also, estimated. The H/C and Haru/Car ratios of the chars were markedly lower than those of coals. This was complemented by higher apparent aromaticities of the chars compared with the coals. 相似文献
3.
A method is described wherein the resolution of31P nuclear magnetic resonance spectra of the lipophilic fraction from a Bligh-Dyer extract of rat brain can be enhanced. The
lipids are dispersed as micelles in aqueous solution with sodium deoxycholate, and spectral resolution is further optimized
by adjusting the pH and by removing ions from the solution. The application of the method to the study of aging in rat brain
serves as an example. 相似文献
4.
Cosmetic oil-in-water emulsions with a stearyl phosphate emulsifier are examined by means of static and dynamic 31P nuclear magnetic resonance (NMR) techniques to characterize the molecular properties of the emulsifier in situ. The interfacially bound emulsifier can be deteced by high-resolution NMR spectroscopy, whereas the excess emulsifier exists
as a solid lipid phase not detectable by this technique. The emulsions and the emulsifier raw material, consisting of monostearyl
phosphate as well as distearly phosphate, are examined by solid state cross polarization magic angle spinning NMR spectroscopy
to prove the existence of solid emulsifier phases in the emulsions. By applying dynamic 31P NMR methods to the interfacially bound emulsifier, information about the molecular dynamics at the interface is obtained.
The results of the T
1 and T
2 relaxation time measurements indicate a restricted motion of the molecules that is dependent on the oil droplet size in the
emulsions. This is verified by 31P NMR pulsed gradient spin echo self-diffusion measurements on emulsions with different droplet sizes. Only about 5 wt% of
the total emulsifier used is bound at the interface; the excess forms solid lipid phases. The coverage of the interface seems
to be independent of the emulsifier concentration. Only the monoester of the emulsifier raw material shows interfacial activity.
Its mobility indicates the two-dimensional environment of the molecules on the surface of the oil droplets. 相似文献
5.
Abnormalities of phospholipids in hypertension have previously been described in human erythrocyte, platelet, and plasma lipoproteins.
Since the heart and kidney are adversely affected by hypertension, we investigated possible alterations in their membrane
phospholipids, which could play a role in the derangement of intracellular ion balance widely observed in hypertension. The
phospholipid compositions of heart and kidney from spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were
determined by using 31P nuclear magnetic resonance (NMR) spectroscopy. Absolute contents of all phospholipids in hypertensive hearts and kidneys
were significantly higher than in normotensive hearts and kidneys. Expressed as a fraction of total phospholipid, cardiolipin
(CL) and phosphatidylethanolamine plasmalogen (PEp) were significantly increased in SHR hearts compared to WKY hearts (CL
and PEp were 7.95±0.22% and 13.16±0.35% in SHR vs. 7.01±0.20% and 11.19±0.42% in WKY rats, P<-0.05), but phosphatidylethanolamine (PE) and phosphatidylcholine (PC) were significantly decreased in SHR (PE and PC were
22.46±0.37% and 44.81±0.43% in SHR vs. 24.02±0.44% and 46.01±0.50% in WKY rats, p≤0.05). In the phospholipids extracted from
rat kidneys, the percentage of PE was significantly higher for SHR than for WKY rats (20.37±0.60% vs. 18.43±0.37%, P≤0.05), while PEp and phosphatidylserine (PS) were significantly lower for SHR (PEp and PS were 10.22±0.36% and 8.42 ±0.28%
in SHRs vs. 11.29±0.36% and 9.71±0.40% in WKY rats, P≤0.05). The above alterations in phospholipid composition might contribute to the higher oxygen consumption in the hypertensive
heart and abnormal intracellular ion concentrations and ion transport in the heart and the kidney in hypertension. 相似文献
6.
7.
M. Hossein Nouri-Sorkhabi Lesley C. Wright David R. Sullivan Philip W. Kuchel 《Lipids》1996,31(7):765-770
31P Nuclear magnetic resonance (NMR) spectra of human erythrocyte lysates dissolved in sodium cholate were acquired. The narrow
resonances of phospholipids were mostly well resolved, allowing identification and accurate quantitative analysis of phospholipid
classes of the erythrocyte membranes. The ether-linked phosphatidylethanolamine components of the erythrocyte membranes were
identified, based on the removal of plasmalogens by acidolysis and of diacyl phospholipid species by degradation using phospholipase
A1. It was also shown that the introduction of double bonds on the acyl chains of phosphatidylcholine shifted the31P NMR resonances to lower frequencies. Quantitative analyses of phospholipids from the spectra were based on their apparent
molar concentrations. The recoveries of phospholipids from erythrocytes were significantly higher than those using conventional
extraction procedures. 相似文献
8.
9.
Proton and 13C nuclear magnetic resonance spectroscopy has been used to derive a series of parameters of an ‘average molecule’ which characterize complex multicomponent organic mixtures such as asphaltenes. The method developed here is based on a minimum of assumptions and takes explicitly into account the effects of the oxygen atoms on the chemical shift of the adjacent 13C atoms. Moreover, the integrated intensities characterizing ring junction or substituted and unsubstituted carbon atoms are no longer determined on a chemical shift basis but are calculated by using parameters extracted from 1H and 13C spectra. Factors influencing quantitative 13C measurements on asphaltenes in the Fourier transform mode are briefly discussed. The variations of parameters such as the aromaticity factor, the degree of substitution, and the number of aromatic and naphthenic cycles per structural unit are studied as functions of depth of burial for rock samples from the Toarcian Paris basin. 相似文献
10.
11.
K.M. McNamara K.K. Gleason D.J. Vestyck J.E. Butler 《Diamond and Related Materials》1992,1(12):1145-1155
The quality of chemically vapor deposited diamond films was assessed in terms of sp2/sp3 content as determined by solid-state nuclear magnetic resonance (NMR) and Raman spectroscopy. While the results of the two techniques are in qualitative agreement, only the NMR spectra yield quantitative values for the sp2/sp3 ratio. Only sp3 carbon was observed in the NMR spectra of very high quality hot-filament, microwave plasma, and d.c. arc-jet chemically vapor deposited films. As expected, Raman spectroscopy is extremely sensitive to sp2 bonded carbon, identifying small amounts below the detection limit of the NMR spectrometer. Comparison of the two techniques, however, indicates that Raman spectroscopy may be so sensitive to sp2 bonded carbon that sp3 bonded carbon in films containing as much as 90% sp3 bonded material may remain undetected. NMR linewidths indicate that the sp3 carbon in such material shows more disorder than that found in high-quality polycrystalline films. 相似文献
12.
13.
A phosphorus-31 nuclear magnetic resonance method has been developed for the determination of aquatic sediment phospholipid
profiles that may be generally applied to all soils and deposits containing viable cellular material. A method of scrubbing
chloroform/methanol extracts with potassium acid phosphate overcomes adverse signal broadening from the mineral component,
permitting eleven sediment phospholipids to be determined at the quantitative level. 相似文献
14.
T. M. Eads A. E. Blaurock R. G. Bryant D. J. Roy W. R. Croasmun 《Journal of the American Oil Chemists' Society》1992,69(11):1057-1068
Deuterium nuclear magnetic resonance (NMR) quadrupole echo spectra of deuterated acyl chains and the glyceryl moiety of tripalmitin
were found to depend on the crystal form. At 20°C, which is below melting points, line shapes indicate that molecular motions
in theβ form (triclinic subcell) are more restricted than inβ′ (orthorhombic) orα (hexagonal). Motional rates in excess of about 20 kHz are responsible for the line shapes. Spin-lattice relaxation, sensitive
to motional frequencies in the tens of megahertz range, is much faster for methyl (CD2) groups inα orβ′ than inβ, indicating that fast motions are also governed by crystal form. General theoretical considerations suggest that motion of
methylene groups is dynamically heterogeneous and that motion of methyl (CD3) groups may be averaged by motions other than rotation about the terminal C-C bond. The isothermal solid-state transition
fromα toβ, induced by increasing the temperature to 35°C, was accompanied by NMR lineshape changes consistent with immobilization.
The reversible transition ofα to “sub-α” upon cooling, accompanied by orthorhombic-like Bragg spacings and other changes in the X-ray pattern and by corresponding
changes in the infrared spectrum, also produced a marked restriction in NMR-detected mobility of the kind seen inβ′ relative toα. The advantages of2H NMR for studies of motions and transitions in solid glycerides are discussed.
Presented at the 80th Annual Meeting of AOCS in Cincinnati, May 1989, and at the 81st Annual Meeting in Baltimore, May 1990. 相似文献
15.
Yuko Miyake Kazuhisa Yokomizo Narihide Matsuzaki 《Journal of the American Oil Chemists' Society》1998,75(12):1091-1094
High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of
edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the
1H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic
acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these
acids by the 13C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC)
method. Results from 13C NMR were in better agreement with those from GC than were the results obtained by the 1H NMR method. 相似文献
16.
17.
Herman Cho Ingrid E. Burgeson Susan R. Adami Sergey I. Sinkov 《Journal of the American Ceramic Society》2020,103(12):7291-7298
The effects of neutron irradiation on lithium aluminate ceramics and the transport and incorporation of tritium into surrounding components are primary concerns in the development of materials for use in tritium production. The high specific activity and volatility of the tritium in activated samples greatly increase the challenges of experimental analysis. This paper reports the determination of structural forms and concentrations of 3H and 6Li in irradiated and nonirradiated LiAlO2 by nuclear magnetic resonance spectroscopy. The experiments find tritium uniformly distributed in hydroxyl groups bridging aluminum centers and lithium in four- and six-coordinated sites. These results demonstrate that measurements can be performed in a nondestructive, safe manner to obtain isotope-selective, quantitative information even on highly hazardous materials. 相似文献
18.
Yuko Miyake Kazuhisa Yokomizo Narihide Matsuzaki 《Journal of the American Oil Chemists' Society》1998,75(1):15-19
High-resolution 1H nuclear magnetic resonance (1H NMR) has been found to be an effective tool for the direct, rapid, and automated determination of the iodine value (IV)
of vegetable oils, including hydrogenated oils (IV=45.9–140.2). The total time required to obtain the 1H NMR data is about 3 min per sample. The IV is calculated from the number of double-bonded protons and the average molecular
weight derived directly from the spectrum. The average of olefinic protons and allylic plus divinyl protons area was used
to calculate the absolute number of double-bonded protons. The 1H NMR results were compared with those obtained by the traditional Wijs-cyclohexane methods. The correlation coefficient between
traditional IV and the novel 1H NMR method was r
2=0.9994 for the regression equation Y=0.9885X + 2.8084, where X was the result given by the traditional method. With the proposed regression equation, IV calculated by the 1H NMR method was within an error of ± 1 unit of the result obtained by the traditional method. The proposed method is practically
viable if one can afford to have the NMR system. 相似文献
19.
20.
Yuko Miyake Kazuhisa Yokomizo Narihide Matsuzaki 《Journal of the American Oil Chemists' Society》1998,75(9):1091-1094
High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the 1H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these acids by the 13C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC) method. Results from 13C NMR were in better agreement with those from GC than were the results obtained by the 1H NMR method. 相似文献