Search results for "Activation"
showing 10 items of 2079 documents
Determination of the apparent activation energy of dielectric relaxation phenomena by means of the representation of ε” as a function of T at constan…
1984
Abstract The main purpose of this work is to justify the use of the positions of the maxima of e” versus T curves when calculating the apparent activation energy in secondary dielectric relaxations or in the relaxation associated with the glass transition. To exemplify this, phenomenological models as well as experimental results for methacrylic polymers are discussed.
Phenylene motion in polycarbonate and polycarbonate/additive mixtures
1987
Pulsed deuteron NMR line shapes have been analysed to characterize type and time scale of the phenylene group motion in glassy bisphenol-A polycarbonate. The motional mechanism involvesπ-flips about theC1C4 axis augmented by small angle fulctuations about the same axis, reaching a rms amplitude of ±35‡ at 380 K. The distribution of correlation times for theπ-flips is heterogeneous in nature and can be described either by a log-Gaussian or an asymmetric distribution with a more rapid decay at high correlation times comparable to the Williams-Watts distribution. From both distributions essentailly the same mean activation energy of 37 kJ/mol is obtained, whereas the temperature dependent widt…
Structural, energetic and kinetic database of catalytic reactions: Benzyl alcohol to benzaldehyde oxidation on MnOx clusters
2021
Abstract Data here reported are connected with the research article “Benzyl Alcohol to Benzaldehyde Oxidation on MnO x Clusters: Unraveling Atomistic Features” Gueci et al. [1] . This work described and discussed structural and energetic results, calculated by Density Functional Theory (DFT). In order to get kinetic information, DFT results were refined by an original approach, which will be shortly described in the following article. The crossed analysis of experimental and computational energetic and kinetic data allowed to (i) reconstruct the complicated lattice that connects the primary and secondary mechanisms of the reaction and (ii) identify alternative process pathways capable of by…
Depletion ofL-arginine induces autophagy as a cytoprotective response to endoplasmic reticulum stress in human T lymphocytes
2012
PMCID: PMC3494587
Y:BaZrO 3 Perovskite Compounds II: Designing Protonic Conduction by using MD Models
2011
The proton dynamics in Y-doped BaZrO(3) derivatives, in particular the different dopant environments within a Pm3m cubic framework, were studied by using classical molecular dynamics (MD) calculations. Single- and double substitution of zirconium by yttrium atoms was considered. The presence of yttrium induced variations in the surrounding oxygen sites, according to their local geometrical arrangements. The differences among such distinct oxygen sites became evident when protons interacted with them and upon changes in the temperature. So, different proton transfer pathways, which had different energy barriers, characterized the topologically different oxygen sites. The experimental proton-…
Nouveaux complexes cationiques du groupe 4 comme potentielles paires frustrées de Lewis organométalliques : synthèse, réactivité, catalyse
2017
In 2006, the concept of “frustrated Lewis pairs” (called FLPs) was introduced. The main characteristic of these compounds is their ability to activate cooperatively small molecules without the use of a metal (H2, CO2, alkene alkyne…). Initially based on P/B combination, the concept has been extended to several other main group elements (N/B, P/Al, N/Al …). Recently, FLPs have been extended to the transition metal realm. These organometallic FLPs (OmFLPs) are obviously non-metal free systems but they extend significantly the scope of FLP applications. Seeking to develop such systems, a research toward new omFLP combinations (N/Ti+, N/Zr+) has been initiated in our group, based on the synthes…
Kondrat'eva ligation: Diels-Alder-based irreversible reaction for bioconjugation.
2014
International audience; Diversification of existing chemoselective ligations is required to efficiently access complex and well-defined biomolecular assemblies with unique and valuable properties. The development and bioconjugation applications of a novel Diels-Alder-based irreversible site-specific ligation are reported. The strategy is based on a Kondrat'eva cycloaddition between bioinert and readily functionalizable 5-alkoxyoxazoles and maleimides that readily react together under mild and easily tunable reaction conditions to afford a fully stable pyridine scaffold. The potential of this novel bioconjugation is demonstrated through the preparation of fluorescent conjugates of biomolecul…
Adaptations neuromusculaires des muscles extenseurs du genou : contractions fatigantes uni- vs bi-latérales
2010
The aim of this work was to determine i) the influence of the level of absolute force on the duration of the endurance time, and subsequent neuromuscular alterations in same individual at the end of an exercise performed at the same relative intensity, with one or two legs, ii) the influence of central drive on the force capacity production of the knee extensor muscles during unilateral (UL) vs. bilateral (BL) contractions, iii) activation mechanisms evolution for a serie of submaximal evoked contractions by electrostimulation (EMS). The results of the first study confirm that the endurance limit depends on the level of absolute force for the same individual, contraction duration for UL is …
Effect of the pea (Pisum sativum L.) gene PsSym36 on Glomus intraradices gene expression
2007
International audience; The Pisum sativum L. mutant RisNod24 (Pssym36) is defective for arbuscular mycorrhiza formation in late stages of AM. Recent studies identified some plant genes up- and down- regulated at stage of arbuscular development using pea mutant RisNod24, but nothing is still known about fungal gene inactivation. To investigate effect of PsSym36 pea gene on fungal gene expression, Glomus intraradices genes which have been previously identified as markers of successful symbiosis development (Seddas et al., unpublished results) were chosen. List of AM genes used in this study: signalling, transcription, protein turn-over (RHO/GDP dissociation inhibitor, Peptidylprolyl isomerase…
Sākumskolas skolēnu izziņas darbības aktivizēšana latviešu valodas stundās 3.klasē
2019
Bakalaura darba tēma ir “Sākumskolas skolēnu izziņas darbības aktivizēšana latviešu valodas stundās 3. klasēs.” Bakalaura darbu veido trīs nodaļās. •Pirmajā nodaļā tiek izmantota teorētisko avotu apkopojošā analīze- psiholoģijas un pedagoģijas zinātnieku atziņas par izziņas aktivitāti, tās attīstību. •Otrajā nodaļā tiek apskatīts jautājums, kā latviešu valodas stundās pēctecīgi attīstīt sākumskolas skolēniem 3. klasē izziņas darbības. Pētījums balstās uz autoritātēm, kuru aprakstītie paņēmieni un metodes attīsta skolēnu vēlmi un interesi mācīties un apgūt valodas. •Trešajā nodaļā ir apkopoti empīriskā pētījuma rezultāti. Tika izvirzīta hipotēze, ka jaunākā skolas vecuma bērnu izziņas aktivi…