Thermal evolution of MnxOy nanofibres as catalysts for the oxygen reduction reaction.

Manganese oxides (MnxOy) are considered as a promising catalyst alternative to platinum in fuel cell applications. In fact, a proper catalyst is needed in order to facilitate the oxygen reduction reaction (ORR) at the cathode, and platinum is considered the best material due to its low overpotential for this reaction. Contrary to platinum, MnxOy is inexpensive, environmentally friendly and can be shaped into several nanostructures; furthermore, most of them show significant electro-catalytic performance. Several strategies have been carried out in order to increase their efficiency, by preparing light and high-surface area materials. In this framework, nanofibres are among the most promising nanostructures that can be used for this purpose. In this work, a study of the thermal, morphological and catalytic behavior of MnxOy nanofibres obtained through the electrospinning technique is proposed. Emphasis is given to the thermal evolution of the precursors, proposing a possible crystallization mechanism of the different manganese oxides obtained. It turns out that manganese oxide nanofibres exhibit good catalytic performance for the ORR, comparable to those obtained by using Pt-based catalysts.

Nanostructural evolution of one-dimensional BaTiO3 structures by hydrothermal conversion of vertically aligned TiO2 nanotubes.

The use of TiO2 nanotube (NT) arrays as templates for hydrothermal conversion of one-dimensional barium titanate (BaTiO3) structures is considered a promising synthesis approach, even though the formation mechanisms are not yet fully understood. Herein we report a nanostructural study by means of XRD and (HR)TEM of high aspect ratio TiO2-NTs hydrothermally converted into BaTiO3. The nanostructure shows two different and well-defined regions: at the top the conversion involves complete dissolution of NTs and subsequent precipitation of BaTiO3 crystals by homogeneous nucleation, followed by the growth of dendritic structures by aggregation and oriented attachment mechanisms. Instead, at the bottom, the low liquid/solid ratio, due to the limited amount of Ba solution that infiltrates the NTs, leads to the rapid crystallization of such a solution into BaTiO3, thus allowing the NTs to act as a template for the formation of highly oriented one-dimensional nanostructures. The in-depth analysis of the structural transformations that take place during the formation of the rod-like arrays of BaTiO3 could help elucidate the conversion mechanism, thus paving the way for the optimization of the synthesis process in view of new applications in energy harvesting devices, where easy and low temperature processing, controlled composition, morphology and functional properties are required.

Second cadaveric kidney transplantations in the pediatric population.

OBJECTIVE: To evaluate the functional outcomes and complications among a series of second in comparison to first kidney transplantations in pediatric patients. MATERIALS AND METHODS: We reviewed 163 consecutive kidney transplants in pediatric recipients performed from 1978 to present: 120 cases (69.3%) were first transplants (group A) and 43 (24.8%), second transplant (group B). We analyzed the incidences of delayed graft function (DGF), medical and surgical complications, as well as medium- and long-term graft survivals. RESULTS: We observed DGF among 51 group A patients (43%) versus 32.5% of group B. Ten patients suffered vascular complications in group A (8.3%) versus one in group B (2.3%) (P < .05). The 15-year graft survivals were 54.2% for group A and 45% for group B. The 15-year patient survivals were 84.9% in group A versus 93.6% in group B. CONCLUSIONS: Second kidney transplantations for children are a satisfactory option that achieves good functional results as well as acceptable graft and patient survivals.

Trends in antiepileptic drug prescribing for older patients with new-onset epilepsy: 2000-2004.

BACKGROUND: Newer antiepileptic drugs (AEDs) have been shown to be equally efficacious as older seizure medications but with fewer neurotoxic and systemic side effects in the elderly. A growing body of clinical recommendations based on systematic literature review and expert opinion advocate the use of the newer agents and avoidance of phenobarbital and phenytoin. This study sought to determine if changes in practice occurred between 2000 and 2004--a time during which evidence and recommendations became increasingly available. METHODS: National data from the Veterans Health Administration (VA; inpatient, outpatient, pharmacy) from 1998 to 2004 and Medicare data (1999-2004) were used to identify patients 66 years and older with new-onset epilepsy. Initial AED was the first AED received from the VA. AEDs were categorized into four groups: phenobarbital, phenytoin, standard (carbamazepine, valproate), and new (gabapentin, lamotrigine, levetiracetam, oxcarbazepine, topiramate). RESULTS: We found a small reduction in use of phenytoin (70.6% to 66.1%) and phenobarbital (3.2% to 1.9%). Use of new AEDs increased significantly from 12.9% to 19.8%, due primarily to use of lamotrigine, levetiracetam, and topiramate. CONCLUSIONS: Despite a growing list of clinical recommendations and guidelines, phenytoin was the most commonly used antiepileptic drug, and there was little change in its use for elderly patients over 5 years. Research further exploring physician and health care system factors associated with change (or lack thereof) will provide better insight into the impact of clinical recommendations on practice.

[Emphysematous pyelonephritis]. / Pielonefritis enfisematosa.

OBJECTIVE: To present an uncommon but startling case of a urinary tract infectious disease such as renal emphysematous pyelonephritis. METHOD/RESULTS: We report the case of a decompensated diabetic female patient who presented an intrarenal infectious picture with gas formation compatible with emphysematous pyelonephritis that showed good evolution following medical treatment and simple nephrectomy surgery. CONCLUSIONS: Emphysematous pyelonephritis is a serious infective disease that occurs almost exclusively in diabetic patients and requires a fast and correct diagnosis differentiating between diffuse from focused processes in order to advise conservative or aggressive therapy on the renal unit (percutaneous drainage/nephrectomy), based on immediate hemodynamic and antibiotic medical support, due to its serious prognosis such as is described in the literature.