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91.
Franciska Könczöl Nelli Farkas Tímea Dergez J. Belágyi D. Lőrinczy 《Journal of Thermal Analysis and Calorimetry》2005,80(1):201-206
Summary DSC and EPR experiments were performed on human erythrocyte membranes and DPPC vesicles in order to study the effect of the
anaesthetic drug tetracaine on structure and dynamics of the lipid region. Experiments using spin label technique showed that
tetracaine induced fluidity changes of the lipid region in the environment of the fatty acid probe molecules incorporated
into the membranes in the vicinity of the lipid-water interface. Similarly to EPR observations, DSC measurements reported
decrease of the main melting and the pretransition temperature in comparison to control DPPC vesicles, which is the sign of
destabilisation of the structure in the head group region of the lipids. Similar effect was observed in the case of erythrocytes
where the protein conformation was also controlled in the presence of drug. A separated membrane melting with well distinguished
membrane protein phase transition was found that was affected significantly by tetracaine. These results suggest that tetracaine
is able to modify not only the internal dynamics of erythrocyte membranes and produce destabilisation of the lipid structure,
but the protein system as well. These might lead to further damage of the biological functions. 相似文献
92.
Application of pressurized liquid extraction technology to pharmaceutical solid dosage form analysis
Hoang TH Farkas R Wells C McClintock S Di Maso M 《Journal of chromatography. A》2002,968(1-2):257-261
The technique of pressurized liquid extraction has been evaluated for the extraction of active ingredients from pharmaceutical dosage forms using montelukast sodium oral chewable tablets as a model. The extraction method was optimized for the number of extraction cycles, extraction time, extraction solvent composition and temperature. Samples were extracted using two cycles of water for 2 min with a cell temperature of 40 degrees C and a pressure of 1.0 x 10(4) kPa, to disintegrate the tablet, followed by three cycles of methanol for 3 min at 70 degrees C and 1.0 x 10(4) kPa, to solubilize montelukast sodium. The method demonstrated an extraction efficiency of 98.2% of label claim and an RSD of 1.3% (n=10), as compared to 97.6% and an RSD of 0.9% obtained using a validated mechanical extraction method. 相似文献
93.
94.
B. Farkas 《Acta Mathematica Hungarica》2003,98(1-2):71-77
Given a measure space < Ω,m,μ >, a locally bounded, Hausdorff topological linear space < X, τ > and a real number 0<p<1, one can define the space Lp(Ω,m,μ,X), which is, under certain assumptions, a Fréchet space if endowed with a suitable topology. M.M. Day [1] has given a necessary
and sufficient condition, in terms of the properties of the measure space < Ω,m,μ >, for the dual of Lp(Ω,m,μ,C) to be trivial. In this paper a different proof along with a slight generalization is given for this result, using standard
and elementary measure theoretic arguments.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
95.
96.
97.
DFT computations were performed on the SN1 and SN2 solvolyses of substituted cumyl chlorides and benzyl chlorides in ethanol and water, by increasing stepwise the C? Cl distance and by optimization. The total energy increases with the increase in the Cl? C distance in SN1 reactions, while free energy of activation pass through maximum. To validate the results, the calculated free energies of activation were compared with data obtained by kinetic measurements. The structural parameters of the transition states were correlated with the Hammett substituent constants and compared with the data of hydrolyses of tert‐butyl chloride and methyl chloride, which proceed with known mechanisms. Conclusions on the mechanisms of the reactions were driven from the effect of substituents on free energies of activation. Cumyl chlorides substituted with electron‐donating (e‐d) groups solvolyze with SN1 mechanism, while the reactions of substrates that bear electron‐withdrawing groups proceed with weak nucleophilic assistance of the solvent. Benzyl chlorides hydrolyze through an SN2 pathway except those derivatives that have strongly e‐d groups, where the reaction has SN1 character, but a weak nucleophilic assistance of the water should also be taken into consideration. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
98.
We investigate a simple model corresponding to particles driven in opposite directions and interacting via a repulsive potential. The particles move off-lattice on a periodic strip and are subject to random forces as well. We show that this model-which can be considered as a continuum version of some driven diffusive systems-exhibits a paradoxical, new kind of transition called here "freezing by heating." One interesting feature of this transition is that a crystallized state with a higher total energy is obtained from a fluid state by increasing the amount of fluctuations. 相似文献
99.
The average transverse momenta in semi-inclusive and associated semi-inclusive distributions are investigated as a function of the prong number. The predictions of the statistical chain model of hadron clusters are compared with data and good agreement is found. 相似文献
100.