Application of low-cost Gallium Arsenide light-emitting-diodes as kerma dosemeter and fluence monitor for high-energy neutrons.

Displacement damage (DD) caused by fast neutrons in unbiased Gallium Arsenide (GaAs) light emitting diodes (LED) resulted in a reduction of the light output. On the other hand, a similar type of LED irradiated with gamma rays from a (60)Co source up to a dose level in excess of 1.0 kGy (1.0 x 10(5) rad) was found to show no significant drop of the light emission. This phenomenon was used to develop a low cost passive fluence monitor and kinetic energy released per unit mass dosemeter for accelerator-produced neutrons. These LED-dosemeters were used to assess the integrated fluence of photoneutrons, which were contaminated with a strong bremsstrahlung gamma-background generated by the 730 MeV superconducting electron linac driving the free electron laser in Hamburg (FLASH) at Deutsches Elektronen-Synchrotron. The applications of GaAs LED as a routine neutron fluence monitor and DD precursor for the electronic components located in high-energy accelerator environment are highlighted.

Metalloantimalarials: targeting of P. falciparum strains with novel iron(III) and gallium(III) complexes of an amine phenol ligand.

Emergence of chloroquine (CQ)-resistant Plasmodium falciparum strains necessitates discovery of potent and inexpensive antimalarial drugs. The high cost of new drugs negatively impacts their access and distribution in the regions of the world with scarce economic resources. While exploring structure-activity relationships, using gallium(III) as a surrogate marker for iron(III), we found cationic, and moderately hydrophobic, compounds, [[1,12-bis(2-hydroxy-3-ethyl-benzyl)-1,5,8,12-tetraazadodecane]metal(III)](+) (metal = Fe(III) and Ga(III); [Fe-3-Eadd](+), 3; [Ga-3-Eadd](+), 4), that possessed antimalarial activity. Crystal structure analyses revealed octahedral geometry for these complexes. The RP-HPLC analysis, after incubation in PBS or HEPES buffer (pH 7.4) at 37 degrees C for 3 days, detected only parental compounds thereby providing evidence for stability under physiological conditions. Both 3 and 4 demonstrated promising half-maximum inhibitory concentration (IC(50)) values of approximately 80 and 86 nM in the CQ-sensitive HB-3 line, respectively. However, both 3 and 4 were found to possess elevated IC(50) values of 2.5 and 0.8 microM, respectively, in the CQ-resistant Dd2 line, thus displaying preferential cytotoxicity toward the CQ-sensitive HB3 line. In cultured parasites, 3 and 4 targeted hemozoin formation. Thus, these compounds acted similarly to chloroquine with regard to action and resistance, despite the lack of structural similarity to quinolines. Finally, similarity in coordination chemistry, stability, and antimalarial cytotoxicity profiles indicated that gallium(III) ion can serve as a template for iron(III) in structure elucidation of active molecules in solution.