On the stability in alkaline conditions and electrochemical performance of A2BO4-type cathodes for liquid fuel cells.

Typical direct liquid fuel cells (DLFCs) use a liquid fuel and O2 as the oxidant. However, for applications where O2 is not available (e.g., space and underwater), the gas has been replaced by H2O2 as a liquid oxidant. This work presents a study of various ceramic disc electrodes with K2NiO4 structure and nominal compositions La2NiO4, La2CuO4, La1.9Pr0.1CuO4, La1.9Sr0.1CuO4, La1.8Ce0.2NiO4, La1.9Pr0.1NiO4, La1.8Pr0.2NiO4 and La1.9Sr0.1NiO4 to assess their stability and activity for the hydrogen peroxide reduction reaction (HPRR) in alkaline media. Stability tests conducted in 2 M NaOH show that Ni and Cu are readily dissolved, as occurs for substituting elements such as Sr, in agreement with calculated Pourbaix diagrams. Such degradation affects the surface of the materials, which is depleted of transition metals. This has consequences for the ORR and HPRR activity due to formation of a La-rich passivation layer on the surface. Only La2CuO4 and La1.8Ce0.2NiO4 display HPRR activity at around -0.25 V vs. RHE. An attempt is made to correlate the composition, chemical stability and electrochemical behaviour of these materials based on known molecular-orbital models proposed for the oxygen reduction reaction.

Epidemiology of brain death and donation rate in the state of Rio Grande do Sul, Brazil: analysis between 1988 and 2004.

OBJECTIVE: To evaluate changes in the profile of potential dead donors brain as to age, gender, and cause of death between 1988 to 2004, as well as the notification rates of potential donors, the donation itself, and family non-authorization. PATIENTS AND METHODS: Records of 2,757 potential donors were reviewed in three periods: I: 1988-1992 (n = 465), II: 1993-1997 (n = 567), and III: 1998-2004 (n = 1,725). RESULTS: The mean age which was similar in periods I and II (30.8 and 29.8 years), increased in period III (38.3 + 18.5 years); (P < .05). The frequency of male donors decreased from 71% and 69%, to 57% (P < .05). The cranium-encephalic trauma decreased from 63.2% and 54.7% to 34.8% (P < .05), while the brain-vascular accidents (CVA) increased from 28.0% and 34.5% to 49.4% (P < .05). The rate of potential donors notified increased from 10.7 per million population per year (pmp/y) and 11.9 to 24.6 pmp/y, while the donation rate increased from 4.4 pmp/y (42.4%) and 7.7 pmp/y (64.3%) to 9.6 pmp/y (38.8%), in periods I, II and III, respectively. The family's nonauthorization changed from 41.5% and 21.7% to 31.9%. CONCLUSIONS: We observed a similar trend as that in developed countries, that is, a significant increases in the ages of potential donors, in the proportion of female donors, and in the CVA brain death. There has been a significant increase in the notification rate and the donation itself, without a significant modification in family nonauthorization rate.

Organ donation in suicides.

INTRODUCTION: There are few reports in the literature analyzing brain death epidemiology in suicides, or the rate of donation and family authorization in such situations. OBJECTIVE: The objectives of this study were to analyze the frequency of suicide as a cause of brain death and to compare the donation rates among this population with other causes of brain death. PATIENTS AND METHODS: We reviewed records from 2627 potential donors between 1988 and 2004. RESULTS: Within that period, 101 (3.8%) cases of brain death were recorded as suicides. The mean age was significantly lower (P < .05) in cases of suicide than for other causes (26.2 + 11.1 vs 34.4 + 16.5 years); there was a male prevalence (76.2% vs 60.8%). As to suicides, the donation rate was significantly higher than in other situations (62.3% vs 43.8%). This was due to a lower rate of negative family responses (17.8% vs 32.1%). CONCLUSIONS: Suicide is a frequent cause of brain death (3.8%), mainly among young men. The donation rate in this group is higher than that due to other causes of death because of a lower negative response rate by the family. The explanation remains to be clarified for such a low refusal rate for organ donation by the relatives of potential donors due to suicide.

Brain death caused by electric shock and organ donation in children.

INTRODUCTION: There are still few publications about brain death caused by electric shock and the use of organs for donation in this situation. We sought to present our experience, with brain dead pediatric donors caused by electric shock. MATERIAL AND METHODS: Notification registers of potential donors were analyzed from 1998 to 2005. RESULTS: During this period, 2086 potential donors were secured, of whom 307 (14.7%) were less than 18 years old. Four pediatric potential donors (1.3%) suffered brain death due to anoxia by electric shock. Six kidneys, three livers, six corneas, and three heart valves were used for transplantation. The hearts and the lungs were not offered, because of a lack of compatible patients on the waiting list. The pediatric donors showed significant alterations of cardiac enzymes and two had altered liver enzymes. CONCLUSION: Brain death caused by electric shock is not a contraindication for organ donation. Follow-up of the recipients is necessary to determine if the transplants were successful.