ChemInform Abstract: Detailed Study of a Two-Step Quintet ⇄ Singlet Spin Transition in an Iron(II) Complex (I) with a N3O2 Macrocyclic Ligand and the Kinetics of the Quintet → Singlet Relaxation in the Temperature Range 115-130 K.

ChemInform ◽  
1988 ◽  
Vol 19 (7) ◽  
Author(s):  
E. KOENIG ◽  
G. RITTER ◽  
J. DENGLER ◽  
S. M. NELSON

In the first paper of this series (Burgoyne 1937) the kinetics of the isothermal oxidation above 400° C of several aromatic hydrocarbons was studied. The present communication extends this work to include the phenomena of ignition in the same temperature range, whilst the corresponding reactions below 400° C form the subject of further investigations now in progress. The hydrocarbons at present under consideration are benzene, toluene, ethylbenzene, n -propylbenzene, o-, m - and p -xylenes and mesitylene.


Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 891
Author(s):  
Yongxuan Chen ◽  
Kefeng Xie ◽  
Yucheng He ◽  
Wenbing Hu

We report fast-scanning chip-calorimetry measurement of isothermal crystallization kinetics of poly(glycolic acid) (PGA) in a broad temperature range. We observed that PGA crystallization could be suppressed by cooling rates beyond -100 K s−1 and, after fast cooling, by heating rates beyond 50 K s-1. In addition, the parabolic curve of crystallization half-time versus crystallization temperature shows that PGA crystallizes the fastest at 130 °C with the minimum crystallization half-time of 4.28 s. We compared our results to those of poly(L-lactic acid) (PLLA) with nearby molecular weights previously reported by Androsch et al. We found that PGA crystallizes generally more quickly than PLLA. In comparison to PLLA, PGA has a much smaller hydrogen side group than the methyl side group in PLLA; therefore, crystal nucleation is favored by the higher molecular mobility of PGA in the low temperature region as well as by the denser molecular packing of PGA in the high temperature region, and the two factors together decide the higher crystallization rates of PGA in the whole temperature range.


1990 ◽  
Vol 31 (3) ◽  
pp. 207-212
Author(s):  
Teruo Tanabe ◽  
Katuhito Kanzaki ◽  
Masanori Kobayashi ◽  
Zenjiro Asaki

2001 ◽  
Vol 44 (4) ◽  
pp. 401-404 ◽  
Author(s):  
Fernanda G. A. Ferraz-Grande ◽  
Massanori Takaki

The germination of endangered species Dalbergia nigra was studied and 30.5° C was found as optimum temperature, although the species presented a broad temperature range where germination occurs and light had no effect. The analysis of kinetics of seed germination confirmed the asynchronized germination below and above the optimum temperature. The light insensitive seed and germination also at high temperatures indicated that D. nigra could occur both in understories and gaps where the mean temperature was high.


Author(s):  
E. Busillo ◽  
V. I. Savchenko ◽  
V. S. Arutyunov

Abstract A detailed kinetic modeling of the noncatalytic processes of thermal pyrolysis and steam and carbon dioxide reforming of methane revealed almost completely identical kinetics of the methane conversion in these processes. This suggests that, in the temperature range 1400–1800 K, the initial stage of conversion of methane in all these processes is its thermal pyrolysis. The modeling results agree well with the experimental data on methane pyrolysis. For the temperature range examined, the Arrhenius expressions (pre-exponential factors and activation energy) were obtained in the first-order kinetics approximation for the rate of methane conversion in the processes studied. The expressions derived may be useful for making preliminary estimates and carrying out engineering calculations.


2018 ◽  
Vol 42 (10) ◽  
pp. 7993-8000
Author(s):  
Filip Smrčka ◽  
Přemysl Lubal

The thermodynamics and kinetics of formation/dissociation of Eu(iii) and Tb(iii) with the H2DO2A macrocyclic ligand were studied by time-resolved fluorescence spectroscopy.


Sign in / Sign up

Export Citation Format

Share Document