EXAFS and XANES investigation of (Li, Ni) codoped ZnO thin films grown by pulsed laser deposition.

Ni doped, Li doped and (Li, Ni) codoped ZnO thin films were successfully grown using a pulsed laser deposition technique. Undoped and doped ZnO thin films were investigated using extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge spectroscopy (XANES). Preliminary investigations on the Zn K-edge of the undoped and doped ZnO thin films revealed that doping has not influenced the average Zn-Zn bond length and Debye-Waller factor. This shows that both Ni and Li doping do not appreciably affect the average local environment of Zn. All the doped ZnO thin films exhibited more than 50% of substitutional Ni, with a maximum of 77% for 2% Ni and 2% Li doped ZnO thin film. The contribution of Ni metal to the EXAFS signal clearly reveals the presence of Ni clusters. The Ni-Ni distance in the Ni(0) nanoclusters, which are formed in the film, is shorter with respect to the reference Ni metal foil and the Debye-Waller factor is higher. Both facts perfectly reflect what is expected for metal nanoparticles. At the highest doping concentration (5%), the presence of Li favors the growth of a secondary NiO phase. Indeed, 2% Ni and 5% Li doped ZnO thin film shows %Nisub = 75 ± 11, %Nimet = 10 ± 8, %NiO = 15 ± 8. XANES studies further confirm that the substitutional Ni is more than 50% in all the samples. These results explain the observed magnetic properties.

Two Afro-Trinidadian siblings with end-stage renal disease

The case histories of two Afro-Trinidadian brothers aged 8 and 11 years who developed end-stage renal disease (ESRD) are presented. Neither had had cause in the past to seek medical attention for any renal-related illness. At presentation both had anaemia, growth failure and other clinical and laboratory evidence of ESRD. Kidney histology in one child was consistent with familial juvenile nephronophthisis (NPH). This is common cause of ESRD in children in other countries but it has not been recognized previously in Trinidadian and other West Indian children, and should be considered as a possible aetiology in West Indian children presenting with renal failure.(AU)

Two Afro-Trinidadian siblings with end-stage renal disease.

The case histories of two Afro-Trinidadian brothers aged 8 and 11 years who developed end-stage renal disease (ESRD) are presented. Neither had had cause in the past to seek medical attention for any renal-related illness. At presentation both had anaemia, growth failure and other clinical and laboratory evidence of ESRD. Kidney histology in one child was consistent with familial juvenile nephronophthisis (NPH). This is a common cause of ESRD in children in other countries but it has not been recognized previously in Trinidadian and other West Indian children, and should be considered as a possible aetiology in West Indian children presenting with renal failure.