| 1. |
- Jiang, J. Z., et al.
(författare)
-
Compressibility and thermal expansion of cubic silicon nitride
- 2002
-
Ingår i: Physical Review B (Condensed Matter). - 0163-1829. ; 65:16, s. 1612021-1612024
-
Tidskriftsartikel (refereegranskat)abstract
- The compressibility and thermal expansion of the cubic silicon nitride (c-Si3N4) phase have been investigated by performing in situ x-ray powder-diffraction measurements using synchrotron radiation, complemented with computer simulations by means of first-principles calculations. The bulk compressibility of the c-Si3N4 phase originates from the average of both Si-N tetrahedral and octahedral compressibilities where the octahedral polyhedra are less compressible than the tetrahedral ones. The origin of the unit cell expansion is revealed to be due to the increase of the octahedral Si-N and N-N bond lengths with temperature, while the lengths for the tetrahedral Si-N and N-N bonds remain almost unchanged in the temperature range 295-1075 K.
|
|
| 2. |
- Frost, B.-M., et al.
(författare)
-
Vincristine in childhood leukaemia : No pharmacokinetic rationale for dose reduction in adolescents
- 2003
-
Ingår i: Acta Paediatrica. - 0803-5253 .- 1651-2227. ; 92:5, s. 551-557
-
Tidskriftsartikel (refereegranskat)abstract
- Aim: To investigate whether there is any pharmacokinetic rationale for the common practice of administering vincristine to adolescents at relatively lower doses than those to younger children. Methods: A total of 98 children, aged 1.3-17.3 y, with acute lymphoblastic leukaemia (ALL) were studied on day 1 of induction therapy. Plasma samples were drawn before and 10, 30, 360 and 1380 min after injection of vincristine 2.0 mg/m2 (maximum dose 2.0 mg) and analysed by high-performance liquid chromatography. Results: The median value (and range) for distribution half-life was 6.4 min (0.8-11.8), elimination half-life 1014 min (258-2570), volume of distribution 445 L/m 2 (137-1241) and total body clearance 362 ml/min/m2 (134-2553). No correlation was found between age and any of these pharmacokinetic parameters. The area under the concentration time curve (AUC) was significantly correlated to age (p = 0.002, ?-0.31), as expected from the dosage of vincristine. The lower AUC in children with a body surface area > 1 m2, which is reached at 8-9 y of age, indicates that they received a less intense treatment because of the capping of the vincristine dose at 2.0 mg. Conclusions: Vincristine pharmacokinetics were not age dependent in this paediatric population. Thus, we found no pharmacokinetic rationale for dose reduction in adolescents. The common practice of limiting the vincristine dose to 2.0 mg should be carefully reconsidered.
|
|
| 3. |
- Horváth, E., et al.
(författare)
-
Investigation of mandelic acid bonding on Pirkle type chromatographic stationary phases by Raman spectroscopy
- 2000
-
Ingår i: Journal of Chromatography A. - 0021-9673 .- 1873-3778. ; 893:1, s. 37-46
-
Tidskriftsartikel (refereegranskat)abstract
- The bonding of mandelic acid enantiomers has been studied on benzene-leucine, dinitrobenzene-leucine and dinitrobenzene-phenylalanine type chiral stationary phases connected to zeolite A supports. The π-donor, π-acceptor and H-bonding interactions responsible for diastereomer pair formations can be studied under quasi in situ chromatographic conditions by Fourier transform Raman and surface enhanced Raman spectroscopic techniques. Structural differences between diastereomer pairs result in observable spectral differences at a phase load of approx. 50%. It was shown that the decreasing π-acceptor character of the phase is associated with its increasing capability of H-bond formation. Correlating spectral data to chromatographic results it can be concluded that, in addition to H-bonding as well as to π-donor-π-acceptor interactions, steric hindrances due to bulky moieties of either the stationary phase or the analyte molecules are of importance in successful separations.
|
|
