Melamine–formaldehyde resins: Molecular species distributions of methylolmelamines and some kinetics of methylolation

1977 ◽  
Vol 15 (10) ◽  
pp. 2347-2365 ◽  
Author(s):  
Bunichiro Tomita
Keyword(s):  
Molecular Species ◽  
Species Distributions ◽  
Melamine Formaldehyde ◽  
Kinetics Of

Kinetics of Selective Acylation of sn-Glycerol 3-Phosphate in the Synthesis of Phospholipid Molecular Species

1979 ◽  
Vol 85 (6) ◽  
pp. 1527-1529 ◽  
Author(s):  
Makoto KITO ◽  
Masataka ISHINAGA ◽  
Masateru NISHIHARA ◽  
Ryuhei KANAMOTO ◽  
Kei-ichi YAMAMOTO ◽  
...  
Keyword(s):  
Molecular Species ◽  
Phospholipid Molecular Species ◽  
Selective Acylation ◽  
Kinetics Of

scholarly journals Biosynthesis of phosphatidylethanolamines and phosphatidylcholines from ethanolamine and choline in rat liver

1975 ◽  
Vol 146 (2) ◽  
pp. 309-315 ◽  
Author(s):  
R Sundler ◽  
B Akesson
Keyword(s):  
Rat Liver ◽  
Molecular Species ◽  
Kinetic Models ◽  
Quantitative Data ◽  
Specific Radioactivity ◽  
Similar Rate ◽  
Time Intervals ◽  
Previous Suggestion ◽  
Kinetics Of

1. The kinetics of phosphatidylcholine and phosphatidylethanolamine synthesis in rat liver were followed 5-60 min after the intraportal injection of [14-C]choline and [3-H]-ethanolamine. 2. At all time-intervals the specific radioactivity of CDP-choline was only about half that of phosphorylcholine. This indicated that CDP-choline was formed at a similar rate from phosphorylcholine and phosphatidylcholines, the latter probably through the reverse reaction of cholinephosphotransferase (EC 2.7.8.2.). In view of recent data obtained from experiments in vitro this implies a significant role for the cholinephosphotransferase reaction in the turnover of molecular species of phosphatidylcholine. 3. The specific radioactivity of CDP-ethanolamine was about twice that of phosphorylethanolamine at all time-intervals studied. This supports a previous suggestion that the liver phosphorylethanolamine pool is subject to compartmentation and shows that there is no rapid equilibration between different pools. In contrast with a recent study, no evidence was found for any significant methylation of phosphoryl-or CDP-ethanolamine to the corresponding choline derivative. 4. Quantitative data on the biosynthesis of molecular species of phosphoLIPIDS via CDP derivatives were calculated according to simple kinetic models. They were in the same range as those calculated from earlier data on precusors incorporated via diacylglycerols. 5. The proportion of radioactive phosphatidylethanolamines appearing in the plasma was approximately ten times lower than that for phosphatidylcholines. No selectivity was observed in the transfer into plasma of different molecular species of phosphatidylethanolamine.

scholarly journals Release of Melamine and Formaldehyde from Melamine-Formaldehyde Plastic Kitchenware

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3629
Author(s):  
Ingo Ebner ◽  
Steffi Haberer ◽  
Stefan Sander ◽  
Oliver Kappenstein ◽  
Andreas Luch ◽  
...  
Keyword(s):  
Activation Energy ◽  
Deionized Water ◽  
Curing Process ◽  
Release Behavior ◽  
Melamine Formaldehyde ◽  
Hot Plate ◽  
Contact Materials ◽  
Kinetics Of ◽  
Cp Mas 13C Nmr

The release of melamine and formaldehyde from kitchenware made of melamine resins is still a matter of great concern. To investigate the migration and release behavior of the monomers from melamine-based food contact materials into food simulants and food stuffs, cooking spoons were tested under so-called hot plate conditions at 100 °C. Release conditions using the real hot plate conditions with 3% acetic acid were compared with conditions in a conventional migration oven and with a release to deionized water. Furthermore, the kinetics of the release were studied using Arrhenius plots giving an activation energy for the release of melamine of 120 kJ/mol. Finally, a correlation between quality of the resins, specifically the kind of bridges between the monomers, and the release of melamine, was confirmed by CP/MAS 13C-NMR measurements of the melamine kitchenware. Obviously, the ratio of methylene bridges and dimethylene ether bridges connecting the melamine monomers during the curing process can be directly correlated with the amount of the monomers released into food.

Mass spectroscopic analysis of phosphatidylinositol synthesis using 6-deuteriated-myo-inositol: comparison of the molecular specificities and acyl remodelling mechanisms in mouse tissues and cultured cells

2004 ◽  
Vol 32 (6) ◽  
pp. 1057-1059 ◽  
Author(s):  
A.D. Postle ◽  
H. Dombrowsky ◽  
H. Clarke ◽  
C.J. Pynn ◽  
G. Koster ◽  
...  
Keyword(s):  
Molecular Species ◽  
Cultured Cells ◽  
Ionization Mass ◽  
Membrane Composition ◽  
Mouse Tissues ◽  
Wide Range ◽  
Kinetics Of ◽  
Hydrolysis Of

Mammalian cell PtdIns (phosphatidylinositol) in vivo is enriched in the sn-1-stearoyl 2-arachidonoyl species, the physiological precursor of phosphatidylinositol 4,5-bisphosphate. Mechanisms regulating this specificity are unclear but are typically lost for cells in culture. We used ESI-MS (tandem electrospray ionization-mass spectrometry) to determine the molecular species of PtdIns synthesized by mouse tissues in vivo compared with cultured cells in vitro. After incorporation of deuteriated myo-d6-inositol over 3 h, endogenous and newly synthesized PtdIns and lysoPtdIns species were quantified from precursor scans of m/z 241− and m/z 247− respectively. PtdIns was synthesized as a wide range of species irrespective of the final membrane composition. Analyses of isotope enrichments argued against acyl remodelling as the major regulatory mechanism: composition of the lysoPtdIns pool under all conditions reflected that of either endogenous or newly synthesized PtdIns and was always at equilibrium. The kinetics of PtdIns synthesis, together with the prolonged time scale required for achieving final equilibrium compositions suggest that selective transport between membranes and/or hydrolysis of selected molecular species are the most probable mechanisms regulating compositions of PtdIns and, ultimately, phosphatidylinositol 4,5-bisphosphate.

Identification and kinetics of oxidized compounds from phosphatidylcholine molecular species

2010 ◽  
Vol 119 (3) ◽  
pp. 1233-1238 ◽  
Author(s):  
Julie Le Grandois ◽  
Eric Marchioni ◽  
Saïd Ennahar ◽  
Francesca Giuffrida ◽  
Françoise Bindler
Keyword(s):  
Molecular Species ◽  
Kinetics Of

Phospholipid molecular species distributions of Candida isolates from the UK and Iran

2003 ◽  
Vol 95 (4) ◽  
pp. 883-889 ◽  
Author(s):  
A.Z. Mahmoudabadi ◽  
V. Boote ◽  
J. Verran ◽  
E. Johnson ◽  
D.B. Drucker
Keyword(s):  
Molecular Species ◽  
Species Distributions ◽  
Phospholipid Molecular Species ◽  
The Uk

Kinetics of the addition stage in the melamine–formaldehyde reaction

1966 ◽  
Vol 10 (8) ◽  
pp. 1153-1170 ◽  
Author(s):  
M. Gordon ◽  
A. Halliwell ◽  
T. Wilson
Keyword(s):  
Melamine Formaldehyde ◽  
Kinetics Of

scholarly journals THE KINETICS OF INACTIVATION OF COMPLEMENT BY LIGHT

1920 ◽  
Vol 3 (2) ◽  
pp. 169-183
Author(s):  
S. C. Brooks
Keyword(s):  
Temperature Coefficient ◽  
Molecular Species ◽  
Wave Length ◽  
Ultra Violet ◽  
Limiting Factor ◽  
Monomolecular Reaction ◽  
Rate Of Reaction ◽  
Effective Wave ◽  
Kinetics Of ◽  
Coefficient Of Diffusion

The photoinactivation of complement has been studied with a view to determining if possible how many kinds of molecules disappeared during the reaction. It was found that: 1. The apparent course of photoinactivation is that of a monomolecular reaction. 2. Diffusion is not the limiting factor responsible for this fact, because the temperature coefficient of diffusion is much higher than that of photoinactivation (Q10 = 1.22 to 1.28, and Q10 = 1.10 respectively). 3. There is no change in the transparency of serum solutions during photoinactivation, at least for light of the effective wave-length, which is in the ultra-violet region probably at about 2530 Ångström units. It is pointed out that under these conditions only one interpretation is possible; namely, that during photoinactivation a single disappearing molecular species governs the rate of reaction. This substance must be primarily responsible for the hemolytic power of serum when it is used as complement.

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