The incorporation site of Er in nanosized CaF2.

The incorporation site of Er dopants inserted at high and low concentration (respectively 5 and 0.5 mol%) in nanoparticles of CaF2 is studied by x-ray absorption spectroscopy (XAS) at the Er L III edge. The experimental data are compared with the results of structural modeling based on density functional theory (DFT). DFT-based molecular dynamics is also used to simulate complete theoretical EXAFS spectra of the model structures. The result is that Er substitutes for Ca in the structure and in the low concentration case the dopant ions are isolated. At high concentration the rare earth ions cluster together binding Ca vacancies.

In situ observation of the Yb2+ emission in the radiodarkening process of Yb-doped optical preform.

This Letter relates the clear evidence of Yb2+ formation under 2.5 MeV electron irradiation in optical fiber preforms showing a darkening of the core. We thus detected by in situ photoluminescence measurements the green emission of divalent Yb2+ under the 355 nm excitation. Moreover, we showed the existence of two types of Yb2+ ion species with different stabilities. We demonstrated that the radiodarkening mechanism is based on a pair association of Yb2+ with aluminum oxygen hole center point defects.

Enhancement of dissolution and bioavailability of flurbiprofen by low molecular weight chitosans.

The dissolution behavior and absorption of flurbiprofen (FP) following oral administration from:three types of chitosans (LM chitosans), with different molecular weights and degree of acetylation, have been studied in comparison with those of the drug alone. The solubility of FP increased with concentrations of LM chitosan, especially in the case of C-III, with the highest degree of deacetylation degree among the three chitosans. This indicates that amino groups of LM chitosan play an important role in its interaction with FP. Moreover, spectroscopic studies, including NMR data, indicate that the binding involves interactions between the carboxyl group of FP and the amino group of the chitosans. The dissolution rates of FP for a C-III kneaded mixture were enhanced with increasing amounts of C-III. The oral absorption of FP from a C-III kneaded mixture was improved to a significant extent, compared to FP alone. These results suggest that FP from LM chitosan kneaded mixture increases the dissolution rate and improves the bioavailability of the drug by the formation of a water-soluble complex.

Influence of absorbed dose and deep traps on thermoluminescence response: a numerical simulation.

Numerical simulations based on standard rate equations are carried out to study the dependence of the thermoluminescence (TL) response on the absorbed dose. The model, which includes thermally stimulated exoelectronic emission (TSEE), uses three electron traps--two active and one thermally disconnected (TD)--and one deep hole trap acting as a recombination centre. After instantaneous creation of a given dose of electron-hole pairs, one first follows isothermal recombination and trap filling before simulating the TL readout. Influence of TD traps and specific effects due to trap saturation are illustrated. A systematic study of the TL response is performed in wide ranges of the determining parameters. The dose dependence is found to be quadratic, linear or intermediate according to their relative values. Results are explained in terms of recombination-trapping competition, trap occupancy and in relation with the presence of TSEE.

Kerma rate effects on thermoluminescent response of CVD diamond.

The thermoluminescence (TL) response of chemical vapour deposition diamond is studied after X-irradiation (45 kV) at room temperature for various air kerma rates ranging from 0.7 to 100 Gy.min(-1). For a given air kerma, the TL signal as a function of air kerma rate exhibits large variations and is higher for low air kerma rates than for higher ones. In order to explain these results, the simplest energy-level scheme has been considered, that is, with only one electron trap and one recombination centre. Kinetic equations are numerically solved. Calculations are made for various electron-hole generation rates and show that the trap filling as a function of electron-hole generation rate follows, actually, the same evolution as the one of experimental TL response. The kerma rate effect on TL response is explained by the competitivity between the recombination and the trapping processes during irradiation.

Bilateral ossification in the Achilles tendon: a case report.

Bilateral symmetrical Achilles tendon ossification is presented, with a fracture on one side. A 57 year old male patient was conservatively treated for bilateral clubfeet in his childhood. Part of his Achilles tendons were replaced by ectopic bony mass and on the left it fractured without any trauma. The fracture was treated surgically by vertical thinning, intraosseal suture "osteosynthesis", and tendon flap plasty. This pathological condition healed in three months. Seven years after the operation the X-ray revealed total bony rebuilding. The ectopic bone mass has the same biological behaviour as the anatomic bones.

[Symmetrical bone formation in the Achilles tendon]. / Szimmetrikus csontosodás Achilles-ínban.

Author reports on a case of ectopic bone formation in the Achilles-tendons and reviews the literature. The pathologic change was caused probably by the chronic mechanical irritation suffered during the conservative treatment of the club feet. The continuity of the ossified mass was interrupted similarly to a fracture; the function was restored after an "osteosynthesis".

[Important aspects of the success of tendolysis]. / Wichtige Gesichtspunkte zum Erfolg der Tendolyse.

After flexor tendon repair, adhesions can occur which interfere with motion. In this situation, surgical tendolysis offers the possibility for improvement in finger function. The authors give the indications and rationale for tendolysis including their own results. Tendolysis was successful in 72% of cases.

[Development of bony bridge between lumbar vertebrae (author's transl)]. / Csontos híd kialakulása lumbális csigolyák között.

Authors report on a case observed in a child developing bony bridge between the transverse processes of lumbar vertebrae. They believe this alteration is a developmental anomaly.