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141.
The lipid ester core aldehydes formed during a rapid oxidation (7.8 M tert-butyl hydroperoxide, 90 min at 37°C) of the triacylglycerols of purified corn and sunflower oils were isolated as dinitrophenylhydrazones
by preparative thin-layer chromatography and identified by reversed-phase high-performance liquid chromatography with on-line
electrospray ionization mass spectrometry and by reference to standards. A total of 113 species of triacylglycerol core aldehydes
were specifically identified, accounting for 32–53% of the 2,4-dinitrophenylhydrazine (DNPH)-reactive material of high molecular
weight representing 25–33% of the total oxidation products. The major core aldehyde species (50–60% of total triacylglycerol
core aldehydes) were the mono(9-oxo)nonanoyl- and mono(12-oxo)-9,10-epoxy dodecenoyl- or (12-oxo)-9-hydroxy-10,11-dodecenoyl-diacylglycerols.
A significant proportion of the total (9-oxo)nonanoyl and epoxidized (12-oxo)-9,10-dodecenoyl core aldehydes was found in
complex combinations with hydroperoxy or hydroxy fatty acyl groups (6–10% of total triacylglycerol core aldehydes). Identified
were also di(9-oxo)nonanoylmonoacylglycerols (0.5% of total) and tri(9-oxo)nonanoylglycerols (trace). The identification of
the oxoacylglycerols was consistent with the products anticipated from tert-butyl hydroperoxide oxidation of the major species of corn and sunflower oil triacylglycerols (mainly linoleoyl esters).
However, the anticipated (13-oxo)-9,11-tridecadienoyl aldehyde-containing acylglycerols were absent because of further oxidation
of the dienoic core aldehyde. A significant proportion of the unsaturated triacylglycerol core aldehydes contained tert-butyl groups linked to the unsaturated fatty chains via peroxide bridges (2–9%). The study demonstrates that rapid peroxidation with tert-butyl hydroperoxide consitutes an effective method for enriching natural oils and fats in triacylglycerol core aldehydes
for biochemical and metabolic testing. 相似文献
142.
The triacylglycerols of winter butterfat were fractionated according to the type and degree of unsaturation into six fractions
by silver ion high-performance liquid chromatography (Ag-HPLC). The acyl carbon number distribution of the triacylglycerols
in each fraction was elucidated by reversed-phase HPLC and mass spectrometry (MS). The MS analysis of each fraction gave deprotonated
triacylglycerol [M - H]− ions which were produced by chemical ionization with ammonia. The daughter spectrum of each of the [M - H]− ions provided information on its fatty acid constituents. Successful fractionation of triacylglycerols differing in the configuration
of one fatty acyl residue by Ag-HPLC was important because geometrical isomers could not be distinguished by the MS system
used. In addition to the fatty acid compositions, reversed-phase HPLC analysis demonstrated the purity of the collected fractions:
molecules having acis-trans difference were separated nearly to the baseline. Triacylglycerols differing in the configuration of one fatty acyl residue
were not equally distributed in relation to their acyl carbon numbers. This indicates that during the biosynthesis of triacylglycerols,cis- andtrans-fatty acids are processed differently. Although the fatty acid compositions of the corresponding molecular weight species
of disaturatedtrans- and disaturatedcis-monoenoic triacylglycerols were similar, there may be differences in the amounts of different fatty acid combinations or
in the distribution of fatty acids between the primary and secondary glycerol positions. In addition to the main components,
it was possible to analyze minor triacylglycerols, such as molecules containing one odd-chain fatty acid, by the MS system
used. 相似文献
143.
The effect of low α-linolenic acid diet on glycerophospholipid molecular species in guinea pig brain
The changes in guinea pig brain (cerebrum) glycerophospholipid molecular species resulting from a low α-linolenic acid (ALA)
diet are described. Two groups of six guinea pigs were raised from birth to 16 wk of age on either an n-3 deficient diet containing
0.01 g ALA/100 g diet or n-3 sufficient diet containing 0.71 g AlA/100 g diet. Molecular species of diradyl glycerophosphoethanolamine.
(GroPEtn), glycerophosphocholine, glycerophosphoserine, and glycerophosphoinositol were analyzed by high-performance liquid
chromatography with on-line electrospray ionization mass spectrometry (HPLC/ESI/MS). Alkenylacyl GroPEtn species were determined
by comparing spectra before and after mild acid treatment while diacyl- and alkylacyl species were distinguished by HPLC/
ESI/MS. The proportions of phospholipid classes and of the diradyl GroPEtn subclasses were not altered by diet changes. The
main polyunsaturated molecular species of diradyl GroPEtn subclasses and of phosphatidylcholine and phosphatidylserine (PtdSer)
contained 16∶0, 18∶0, or 18∶1 in combination with docosahexaenoic acid (DHA, 22∶6n-3), docosapentaenoic (DPA, 22∶5n-6), or
arachidonic acid (ARA, 20∶4n-6). A significant proportion of DPA containing species were present in both diet groups, but
in n-3 fatty acid deficiency, the proportion of DPA increased and DHA was primarily replaced by DPA. The combined value of
main DHA and DPA containing species in the n-3 deficient group ranged from 91-111% when compared with the n-3 sufficient group,
indicating a nearly quantitative replacement. The n-3 fatty acid deficiency did not lower the content of ARA containing molecular
species of PtdSer of the guinea pig brain as reported previously for the rat brain. The molecular species of phosphatidylinositol
were not altered by n-3 fatty acid deficiency. The present data show that the main consequence of a low ALA diet is the preferential
replacement of DHA-containing molecular species by DPA-containing molecular species in alkenylacyl- and diacyl GroPEtn and
PtdSer of guinea pig brain. 相似文献
144.
Oxidized lipoproteins have a recognized role in atherogenesis, but molecular-level research on oxidized lipids in lipoproteins
and the effect of diet on these molecules have been limited. In the present study, the effects of three sunflower seed oil
diets differing in oxidation levels (PV in oils 1, 84, and 223 mequiv O2/kg) on lipoprotein lipid oxidation in growing pigs were investigated. The emphasis was on the investigation of oxidized TAG
molecules found in chylomicrons and VLDL. A method based on RP-HPLC and electrospray ionization-MS was used for the analysis
of oxidized TAG molecules. The baseline diene conjugation method was used for the estimation of in vivo levels of lipoprotein lipid oxidation. Several oxidized TAG structures were found in the samples. These products consisted
of TAG molecules with a hydroxy, an epoxy, or a keto group attached to a FA, and of TAG molecules containing an aldehyde structure
derived from a FA. The lipoprotein lipids and TAG were more oxidized in the pigs fed on the most oxidized oil compared with
those fed on nonoxidized oil. Oxidation of dietary fat was reflected in the lipoprotein oxidation. New, detailed information
on oxidized TAG molecules of chylomicrons and VLDL was obtained. 相似文献
145.
论述了洗涤剂酶的发展趋向。生物工程,基因工程,蛋白质工程及定向分子演变在酶的新品开发和性能改进方面的应用。酶在整体洗涤效果方面的作用除了易于清除直接附着在织物表面的污垢外,还有消除微纤维。短毛和小球的作用。改善织物表面的色泽,清除微粒的残余污垢和保持织物白度,防止织物发灰以及减轻微粒污垢的再沉积作用。 相似文献
146.
Jarkko Etula Katja Lahtinen Niklas Wester Ajai Iyer Kai Arstila Timo Sajavaara Tanja Kallio Ulf Helmersson Jari Koskinen 《Advanced functional materials》2019,29(42)
Here, an unidentified type of micropillar growth is described at room temperature during conventional direct‐current magnetron sputtering (DC‐MS) deposition from a Li4Ti5O12+graphite sputter target under negative substrate bias and high operating pressure. These fabricated carbon–Li2O–TiO2 microstructures consisting of various Li4Ti5O12/Li2TiO3/Lix TiO2 crystalline phases are demonstrated as an anode material in Li‐ion microbatteries. The described micropillar fabrication method is a low‐cost, substrate independent, single‐step, room‐temperature vacuum process utilizing a mature industrial complementary metal–oxide–semiconductor (CMOS)‐compatible technology. Furthermore, tentative consideration is given to the effects of selected deposition parameters and the growth process, as based on extensive physical and chemical characterization. Additional studies are, however, required to understand the exact processes and interactions that form the micropillars. If this facile method is further extended to other similar metal oxide–carbon systems, it could offer alternative low‐cost fabrication routes for microporous high‐surface area materials in electrochemistry and microelectronics. 相似文献
147.
Summary A thermostable polymer, called sulfur lignin, has been obtained when modifying lignin by reactions with elemental sulfur at elevated temperatures. Sulfur linkages are formed between the phenylpropane units of lignin in these reactions. The conductivity of polymers which have a conjugated structure can be increased by doping with electron acceptors or donors. The conductivity of sulfur lignin has been measured after doping with various dopants and from the results it is concluded that the doped sulfur lignin has the properties off a semi conductive polymer. 相似文献
148.
The changes in the triacylglycerol (TAG) composition of colostrum fat of three cows were studied. In addition to the determination
of fatty acid composition by gas chromatography, the distribution of TAG according to the acyl carbon number (ACN) and molecular
weight was analyzed utilizing both supercritical fluid chromatography (SFC) and ammonia negative-ion chemical ionization mass
spectrometry (MS). Colostrum TAG contained substantially less stearic and oleic acids and more myristic and palmitic acids
than the normal Finnish milk fat. The major trends in the changes of fatty acids and TAG were similar for each cow, although
clear differences between individuals were found. During the first week of parturition, the proportions of short-chain fatty
acids (C4–C10) typically increased as well as those of stearic and oleic acids, whereas the relative amounts of C12–C16 acids decreased, especially those of myristic and palmitic acids. Distinct changes occurred also in TAG distributions: the
proportions of molecules with ACN 38–40 increased and those with ACN 44–48 decreased. Although there were distinct differences
between individuals shortly after delivery, both the fatty acid compositions and TAG distributions of the milk samples of
the cows started to resemble each other after one week. The theoretical profiles of colostrum TAG calculated based on the
fatty acid compositions differed clearly from the ACN distributions analyzed by SFC and MS. Thus, the analysis of TAG is essential,
because the changes in molecular species composition of colostrum TAG cannot be estimated according to the fatty acid analysis
alone. 相似文献
149.
Olli Sjövall Erkki Honkanen Heikki Kallio Kyösti Latva-Kala Anna-Maija Sjöberg 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1990,191(3):181-183
Summary Chemical changes due to gamma-irradiation were investigated in 11 pure aroma compounds typically found in spices. Samples were irradiated with doses of 0, 10, and 50 kGy. The irradiation source was60Co. Irradiated samples and unirradiated controls were analyzed by gas chromatography alone and coupled with mass spectrometry. Significant changes due to the irradiation occurred only in (±)-linalool and-terpineol, which are typical components of, for example, coriander and bay leaf. Their total amounts decreased by about 4–13% and some minor peaks increased as a result of irradiation. However, different results may be obtained when the spices themselves are irradiated.
Auswirkungen der -Strahlung auf einige Gewürz-Aromastoffe
Zusammenfassung An elf gewürztypischen Aromastoffen wurden die von der-Strahlung verursachten Veränderungen untersucht. Die Proben wurden unter Verwendung von60Co als Strahlungsquelle mit Dosen von 0, 10 und 50 kGy bestrahlt. Die bestrahlten und unbestrahlten Proben wurden gaschromatographisch (GC) und GC-massenspektrometrisch untersucht. Erhebliche Veränderungen zeigten sich nur beim (±)-Linalool und beim-Terpineol, die zum Beispiel für die ätherischen Öle von Koriander und Lorbeerblatt typisch sind. Die Peaks dieser Aromastoffe reduzierten sich um 4–13%, und dem entsprechend waren einige kleinere Peaks zu beobachten. Es kann dennoch zu unterschiedlichen Resultaten kommen, wenn Gewürze bestrahlt werden.相似文献
150.
Daulet Izbassarov Judit Nyári Bulut Tekgül Erkki Laurila Tanja Kallio Annukka Santasalo-Aarnio Ossi Kaario Ville Vuorinen 《International Journal of Hydrogen Energy》2021,46(29):15635-15648
Synthetic fuels are needed to replace their fossil counterparts for clean transport. Presently, their production is still inefficient and costly. To enhance the process of methanol production from CO2 and H2 and reduce its cost, a particle-resolved numerical simulation tool is presented. A global surface reaction model based on the Langmuir-Hinshelwood-Hougen-Watson kinetics is utilized. The approach is first validated against standard benchmark problems for non-reacting and reacting cases. Next, the method is applied to study the performance of methanol production in a 2D fixed-bed reactor under a range of parameters. It is found that methanol yield enhances with pressure, catalyst loading, reactant ratio, and packing density. The yield diminishes with temperature at adiabatic conditions, while it shows non-monotonic change for the studied isothermal cases. Overall, the staggered and the random catalyst configurations are found to outperform the in-line system. 相似文献