Using a method developed by us, a non-isothermal kinetic study of the thermal decomposition of some coordination compounds (CC) with the general formula MeIILpX2, where , was performed. 相似文献
The results of a kinetic investigation of the non-isothermal degradation and the isothermal degradation of the residual deformation
under constant deflection for polychloroprene rubber are presented. A relationship was derived between the degree of non-isothermal
conversion and the value of the investigated mechanical property.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
We show that the kinetic model of a single rate-determining step in a reaction mechanism can be extended to systems with multiple overall reactions for which the elementary reactions obey nonideal or fractal kinetics. The following assumptions are necessary: (1) The system studied is either closed or open, but no constraints exist preventing the evolution toward equilibrium. (2) Elementary reactions occur in pairs of forward and backward steps. (3) The kinetics of the elementary steps are either nonideal or fractal and are compatible with equilibrium thermodynamics. (4) The number of reaction routes is identical with the number of rate-determining steps. If these hypotheses are valid, then the overall reaction rates can be explicitly evaluated: they have a form similar to the kinetic equations for the elementary reactions and the apparent reaction orders and fractal coefficients can be expressed analytically in terms of the kinetic parameters of the elementary reactions. We derive a set of relationships which connect the equilibrium constants of the reaction routes, the corresponding overall rate coefficients, and the stoichiometric numbers of the rate-determining steps. We also derive a set of generalized Boreskov relations among the apparent activation energies of the forward and backward overall processes, the corresponding reaction enthalpies, and the stoichiometric coefficients of the rate-determining steps. If the elementary reactions obey fractal kinetics, the same is true for the rate-determining steps. The fractal exponents of the forward and backward overall reactions are linear combinations of the fractal exponents of the fractal elementary reactions. Similar to the theory of single rate-determining steps, our approach can be used for selecting suitable reaction mechanisms from experimental data. 相似文献
Trimethylsilyl ethers of various hydroxyl-containing thiazole derivatives have been synthesized. The psychotropic activity (in vivo) and the cytotoxicity (in vitro on tumor cell lines HT-1080 and MG-22A) of these ethers and of their unsilylated precursors have been studied. It was discovered that the obtained compounds possess a sedative action. A moderate cytotoxic effect was detected for piperidine-containing thiazoles, displayed most strongly in relation to MG-22A cells. 相似文献
The dehydration of a series of VPI-5 and H3 samples, synthesized under various conditions, as well as the solid state transformation
of VPI-5 to AlPO4-8 have been investigated using combined TG-DTG-DSC and high-resolution solid state31P-NMR. The TG curves show a quasi-continuous release of water, the total loss being characteristic for each sample. Complete
dehydration is achieved when the samples are heated from 20°C to about 150°C at various beating rates. Besides the main dehydration
effect, several weak endothermic peaks are observed. These generally non-reproducible modulated peaks, recorded at high heating
rates, are presumably due to the interactions of the water molecules leaving the channels of VPI-5 with the randomly positioned
fragments stemming from the destruction of the water triple helix assemblage.
The non-isothermal kinetic parameters of the dehydration have been evaluated from the TG and DTG curves recorded at low heating
rates.
In celebration of the 60th birthday of Dr. Andrew K. Galwey 相似文献
The authors present some theoretical considerations concerning the influence of the form of the conversion functionf() on the values of the degree of conversion corresponding to the maximum value of the reaction rate (max) as well as on the inflexion points (inf) of the DTG curve. The obtained equations are characterized by a general validity no matter the form off().
Zusammenfassung Es werden einige theoretische Überlegungen bezüglich des Einflusses der Form der Konversionsfunktionf() auf die Werte der Konversionsrate bei maximalen Reaktionsgeschwindigkeiten (max) sowie auf Inflexionspunkte () der DTG-Kurve angestellt. Die erhaltenen Gleichungen sind unabhängig von der Form vonf() durch eine all-gemeine Gültigkeit charakterisiert.
Consideration is given to the effect on gel-permeation chromatographic (GPC) data of the extent of substitution in nitrated cellulose. GPC parameters for samples containing 13.55–13.81% nitrogen (14.14% corresponds to complete substitution, DS = 3) were hardly affected by this variation in substitution. Variations that were observed are considered to arise within the samples themselves. Experiments with low molecular weight organic iodides, nitrates, and hydroxyl compounds indicate longer chain lengths than actual; this is attributed to extensive solvation of the substituent groups. The very long chain lengths obtained for cellulose nitrate by the present GPC procedure may arise from such an affect. 相似文献
Water-soluble double-coated magnetic nanoparticles (NPs) containing cytotoxic decyldimethyl(β-dimethylaminoethoxy)silane methiodide (AA) molecule sorbed at biocompatible magnetic particles, which consist of magnetite pre-coated with oleic acid (OA), have been prepared. X-ray line profile broadening analysis was used for crystallite size determination. The method of magnetogranulometry has been used for determination of diameter of iron oxide magnetic core and magnetic properties of NPs prepared. In vitro cytotoxicity on monolayer tumor cell lines HT-1080 (human fibrosarcoma), MG-22A (mouse hepatoma) and normal mouse fibroblasts (NIH 3T3) has been studied. It was revealed that all the water-based colloidal solutions obtained are non-toxic and possess high NO-induction ability. 相似文献