A method is described for the preparation of ganglioside Glac2 [(II3(NeuAc)2-LacCer, GD3] from cream of bovine milk using liquid-phase extraction with methanol or ethanol followed by anion exchange
chromatography. The method is rapid and inexpensive; 1 kg cream, centrifuged from 14–15 L of bovine milk, yields approximately
70 mg of pure ganglioside Glac2. The sialic acid constituent of ganglioside Glac2 isolated from bovine milk cream consists solely of theN-acetylneuraminic acid derivative. The major components of its ceramide consist of octadecasphing-4-enine and the 22∶0 (behenic
acid) and 23∶0 fatty acids.
Short hand notations for gangliosides are according to Wiegandt (Ref. 1). Glac2, (II3(NeuAc)2-LacCer) is NeuAcα,8NeuAcα,-3Galβ,4Glcβ,1Cer; Gtet1, (II3NeuAc-Gg4Cer) is Gal\,3GalNAcβ,-4(NeuAcα,3)Galβ,4Glcβ,1Cer. 相似文献
The X-ray diffraction pattern for potassium-zirconium phosphate is significantly improved when the material is prepared by the sol-gel route rather than the powder method. Peaks at high, low, and intermediate angles are presented and compared for the two methods. It is assumed that the more nearly homogeneous mixing of the elements in the sol-gel process is responsible for the significant improvement in crystallinity. 相似文献
Many Web portals allow users to associate additional information with existing multimedia resources such as images, audio, and video. However, these portals are usually closed systems and user-generated annotations are almost always kept locked up and remain inaccessible to the Web of Data. We believe that an important step to take is the integration of multimedia annotations and the Linked Data principles. We present the current state of the Open Annotation Model, explain our design rationale, and describe how the model can represent user annotations on multimedia Web resources. Applying this model in Web portals and devices, which support user annotations, should allow clients to easily publish and consume, thus exchange annotations on multimedia Web resources via common Web standards. 相似文献
The technological properties of ABS polymers largely depend on the structure of the elastomer phase as well as on the elastomer/thermoplast interface. The morphological structure of such polymers can be determined from electron micrographs of ultramicrotome sections – after selective contrasting of the polybutadiene phase – or of replicas of fracture surfaces after selective chemical degradation. The various ABS polymers are classified by their manufacturing processes and their morphologies and characterized by electron micrographs. The degree and place of grafting are of particular importance. The quantitative determination of the surface- and internal grafting is achieved by combining the determination of the degree of grafting (extraction), the evaluation of the results obtained on particle counting, and a morphometric process. It is demonstrated that the morphometric process can in general be applied for the quantitative determination of the contrastable component in two-phase polymers. 相似文献
13C n.m.r. spectroscopy has been applied to investigate a number of coal tar and petroleum-derived carbon black feedstocks. Application of the J-modulated spin echo technique is especially rewarding, as this method renders the quaternary carbons directly detectable. Thus the quality of carbon black feedstocks can additionally be gauged on the basis of the contents of quaternary carbons, which is a direct indication of the carbon yield in the carbon black production process. 相似文献
Various poly(arylsilane)s The poly(carbosilane)s prepared in this way are of higher molecular weight than when prepared by the Wurtz-type condensation route previously reported. TG shows 40–50% overll weight loss attained at 500–600°C. 相似文献
The purpose of this study was to investigate the temporal relationships of the transport of β-carotene in human lipoproteins.
We administered 60 mg β-carotene with breakfast to nine fasting subjects, then blood samples were collected at intervals of
up to 75 h, lipoproteins were isolated, and β-carotene was quantitated. β-Carotene concentrations in chylomicrons and very
low density lipoproteins (VLDL) peaked at 6 and 9 h, respectively. Nonetheless, at all time points the majority of plasma
β-carotene was contained in low density lipoproteins (LDL), while high density lipoproteins (HDL) carried a smaller portion
(at 24 h, 73±8% in LDL as compared with 23±5% in HDL). In three subjects, transport of β-carotene was compred with the results
of earlier studies on the transport of stereoisomers of α-tocopherol. Unlike plasmaRRR-α-tocopherol concentrations, which are maintained by the preferential incorporation ofRRR-α-tocopherol into VLDL by the liver, β-carotene increased and decreased in VLDL similarly toSRR-α-tocopherol, a stereoisomer whose concentrations are not maintained in plasma. In conclusion, β-carotene is primarily transported
in the plasma in LDL, but its incorporation by the liver into lipoproteins does not appear to be enhanced. 相似文献
Production of a combustible for coal-fired power stations based on sewage sludge . This article describes various means of achieving more extensive mechanical dewatering of sewage sludges. The heat content of the sludge solids can become available for combustion processes. The sludge filter cakes obtained by the “CarboSed” process can be disposed of with minimum energy consumption by fluidized bed combustion or be used after appropriate work-up as a combustible in coal-fired power stations with full exploitation of their heat content for generation of steam and electric current. Partial substitution of primary energy sources such as coal and fuel oil by sludge filter cake is feasible in all cases. The processes thus make a contribution to the saving of energy resources and the disposal of sludge. 相似文献
Zusammenfassung Die Synthese von acht verschiedenen 2-Alkoxy-5-alkyl-tetrahydrofuranen und ihren Stereoisomeren wird vorgestellt, sieben von ihnen sind als Aromastoffe der Wassermelone bekannt. Alle Stereoisomeren werden, ausgehend von optisch reinen-Nonalacton-Enantiomeren, synthetisiert und mit Diisobutylaluminiumhydrid selektiv zu den entsprechenden Lactolen reduziert. Die Lactole werden mit den gewünschten Alkoholen in schwach saurer Lösung zucis/trans-Diastereomeren umgesetzt und durch Flüssigchromatographie in optisch reine Stereoisomere getrennt. Die sensorische Charakteristik aller Stereoisomeren der sieben Verbindungen wird aufgezeigt. Die Trennung dercis/trans-Diastereomeren an DB-210 wird vorgestellt und die chirospezifische Differenzierung der acht Verbindungen diskutiert.
Stereoisomeric flavour compounds L. Optically pure 2-alkoxy-5-alkyl-tetrahydrofurans — structures and properties
Summary The synthesis of eight different 2-alkoxy-5-alkyltetrahydrofurans and their stereoisomers is presented, seven of which are known to be flavour compounds of water melons. All stereoisomers were synthesized from optically pure-lactone enantiomers, which were selectively reduced by diisobutylaluminium hydride to the corresponding lactols. The lactols were treated with the desired alcohol component in weakly acidic media to yield thecis/trans diastereoisomers, which were separated into optically pure stereoisomers by liquid chromatography. The sensory characteristics of all four stereoisomers of the seven compounds are given. The Stereodifferentiation of thesecis/trans diastereoisomers on DB-210 is demonstrated and the direct chirospecific differentiation of all eight compounds discussed.