Characterization of Decomposition Products of Maytansine

1987 ◽  
Vol 76 (9) ◽  
pp. 738-743 ◽  
Author(s):  
John A. Suchocki ◽  
Albert T. Sneden
Keyword(s):  
Decomposition Products

scholarly journals Nanosize CaCu3Ti4O12 Green Synthesis and Characterization of a Precursor Oxalate Obtained from Averrhoa carambola Fruit Juice and Its Thermal Decomposition to the Perovskite

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Ekane Peter Etape ◽  
Josepha Foba-Tendo ◽  
Beckley Victorine Namondo ◽  
Divine Mbom Yufanyi ◽  
Hypolite Mathias Kamta Tedjieukeng ◽  
...  
Keyword(s):  
Fruit Juice ◽  
Thermal Treatments ◽  
Decomposition Products ◽  
Multiple Dimensions ◽  
Different Temperatures ◽  
Synthesis Routes ◽  
High Degree ◽  
Very High ◽  
Oxalic Acids

Improving on the very high temperatures used in solid-state synthesis routes to prepare CCTO ignited the idea of using oxalate routes which make use of organic solvents in the synthesis of CCTOX as oxalate intermediates to the decomposition product, CCTO. The use of commercial oxalic acids and oxalate has not only recorded a solubility problem which reflects on the size, shape, homogeneity, and morphology of the final product but also has an environmental impact originating from the solvents used. Both the composition and morphology of these inhomogeneities play a role in the behaviour of the final product, pointing out the need to assess the dependence of size, shape, homogeneity, and morphology and the material performance on the sample synthesis history. In this study, nanosized particles of calcium copper titanium oxide, CaCu3Ti4O12 (CCTO), were successfully synthesized by pyrolysis of the corresponding heterometal oxalate precursors obtained via coprecipitation using the edible carambola fruit juice as a precipitating agent and investigated in detail. The precursors were characterized, and the results revealed the formation of a single molecular precursor represented by the formula CaCu3(TiO)4(C2O4)8·9H2O (CCTOX). The decomposition products, obtained via calcination in air, were subsequently subjected to thermal treatments at different temperatures for 4 hours. The morphology and microstructure were characterized, and analysis showed the formation of a single phase, CaCu3Ti4O12 (CCTO) with CuO and CaTiO3 as impurity. It was observed from microscopy that the samples obtained from sintering at 600°C for four hours had discrete particles with regular morphology, limited size distribution, high degree of homogeneity, and multiple dimensions ranging between 10 and 35 nm and showed some degree of ellipticity in shape. Increasing the sintering temperature from 600°C to 700°C and 800°C increased the grain growth in the ceramic as well as the densification. The method makes advantage of the fact that oxalate precursors decomposed at relatively lower temperatures and the fact that the oxalate in the juice is in the solution which downplays both the solubility and environmental pollution problems since no additional solvents are used.

Effect of pH and temperature on the stability of cylindrospermopsin. Characterization of decomposition products

2016 ◽  
Vol 15 ◽  
pp. 129-134 ◽  
Author(s):  
Michal Adamski ◽  
Paweł Żmudzki ◽  
Ewelina Chrapusta ◽  
Beata Bober ◽  
Ariel Kaminski ◽  
...  
Keyword(s):  
Decomposition Products ◽  
Effect Of Ph ◽  
The Stability

scholarly journals Bakerian lecture - Amino-acid analysis and the structure of proteins

1942 ◽  
Vol 131 (863) ◽  
pp. 136-160 ◽  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Analysis ◽  
Nutritive Value ◽  
Analytical Data ◽  
Seed Proteins ◽  
Decomposition Products ◽  
First Time ◽  
Structure Of Proteins

In recent years the X-ray crystallographers have made remarkable advances in the interpretation of protein structure, and it is becoming more and more evident that a stage has been reached when their views need to be reconciled with data obtained from accurate amino-acid analysis of the proteins concerned. In all too many cases these data are, unfortunately, not yet available, and the reason why the analyst cannot supply them at short notice is due not so much to the com­plexity of the problem—which he has never sought to minimize—but to the fact that many of the more important methods of analysis in current use are an inheritance from an earlier period when such accuracy as is now demanded would have been considered almost impossible of achievement. From about 1840 until 1900, following the lead given by Liebig and later by Ritthausen, the attention of protein chemists was centred chiefly on the prepara­tion and characterization of various animal and seed proteins; as substances of physiological interest their enzymic digestion products were studied in elaborate detail by Kühne, but little attention was paid to the ultimate decomposition products, the amino-acids, in spite of the fact that Ritthausen as early as 1872 had pointed out that the proportions in which these occur might be characteristic of the protein concerned. The enunciation by Hofmeister and Fischer of the peptide hypothesis in 1901 emphasized for the first time the fundamental importance of the amino-acids, and a most fruitful period followed in which attention became almost exclusively focused on these products. Under the inspiring leadership of Fischer himself great improvements were effected in the separation and identification of the amino-acids, so that by about 1915 reasonably good analyses were available for most of the better-known proteins. Though far from complete, the analytical data showed quite clearly that proteins could differ widely in composition, and in many cases it was possible to correlate composition with nutritive value. Such an aim was, indeed, the incentive behind much of the work of this period.

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