Disruption of extended defects in solid oxide fuel cell anodes for methane oxidation.

Point defects largely govern the electrochemical properties of oxides: at low defect concentrations, conductivity increases with concentration; however, at higher concentrations, defect-defect interactions start to dominate. Thus, in searching for electrochemically active materials for fuel cell anodes, high defect concentration is generally avoided. Here we describe an oxide anode formed from lanthanum-substituted strontium titanate (La-SrTiO3) in which we control the oxygen stoichiometry in order to break down the extended defect intergrowth regions and create phases with considerable disordered oxygen defects. We substitute Ti in these phases with Ga and Mn to induce redox activity and allow more flexible coordination. The material demonstrates impressive fuel cell performance using wet hydrogen at 950 degrees C. It is also important for fuel cell technology to achieve efficient electrode operation with different hydrocarbon fuels, although such fuels are more demanding than pure hydrogen. The best anode materials to date--Ni-YSZ (yttria-stabilized zirconia) cermets--suffer some disadvantages related to low tolerance to sulphur, carbon build-up when using hydrocarbon fuels (though device modifications and lower temperature operation can avoid this) and volume instability on redox cycling. Our anode material is very active for methane oxidation at high temperatures, with open circuit voltages in excess of 1.2 V. The materials design concept that we use here could lead to devices that enable more-efficient energy extraction from fossil fuels and carbon-neutral fuels.

Delayed Leukoencephalopathy: Three Case Reports and a Literature Review.

BACKGROUND: Delayed leukoencephalopathy (DL) is a rare entity associated with cerebral hypoxia and heroin consumption. We describe the clinical course of three cases of DL due to non-heroin drug use. MATERIAL AND METHODS: We describe the cases of three DL patients admitted to our hospital in 2012. DISCUSSION: These cases contribute to the aetiological spectrum of DL since multifactorial causes could account for the clinical symptoms. LEARNING POINTS: Substances toxic to the CNS can damage the CNS directly (direct toxicity) or by depressing the respiratory centre (cerebral hypoxia).As clinical manifestations can appear after a time lag, we recommend a period of initial monitoring.Histological and radiological findings can contribute to better understanding of the pathophysiological mechanisms and causes involved.

Drug-Related Eyelid Nystagmus: Two Cases of a Rare Clinical Phenomenon Related to Carbamazepine and Derivatives.

BACKGROUND: Eyelid nystagmus is a rare clinical phenomenon described mostly related to brainstem or cerebellum lesions. The mechanism of this phenomenon is incompletely understood. PATIENTS AND METHODS: We report 2 cases of eyelid nystagmus induced by carbamazepine and oxcarbazepine intoxication. CONCLUSIONS: Carbamazepine and derivatives may induce eyelid nystagmus in the setting of acute intoxication. To the best of our knowledge, these are the first cases of drug-related eyelid nystagmus.

Rare cause of paraparesis: bilateral obturator neuropathy after hysterosalpingectomy.

Bilateral obturator nerve injury during pelvic surgery is an infrequent cause of lower limb paraparesis. We report the case of a 45-year-old woman with a large uterine leiomyoma who underwent simple total hysterectomy and bilateral salpingectomy. At 24 h after the surgery, the patient noticed loss of muscle strength when adducting both legs. She had no problem with other movements and no sensory or sphincter abnormalities. Neurological examination confirmed that there was loss of strength only in the adductor muscles, with preserved sensory function and reflexes, suggesting bilateral obturator nerve involvement. Pelvic MRI showed a small postsurgical haematoma in the Douglas recess, but far from the obturator nerves. 2 weeks later, electromyography showed positive sharp waves and low motor unit recruitment in the adductor magnus muscles, confirming acute, bilateral obturator nerve neuropathy. The few cases of bilateral obturator neuropathy that have been reported were mostly related to abdominopelvic interventions.

Brain Magnetic Resonance Spectroscopy Findings in the Stroke-like Migraine Attacks after Radiation Therapy (SMART) Syndrome.

A 41-year-old male presented with an acute onset of headache, confusion, seizures, and unilateral focal neurological deficit 25 years after receiving whole-brain radiation therapy to treat a cerebellar medulloblastoma. Brain magnetic resonance imaging (MRI) demonstrated a thick unilateral parieto-occipital cortical contrast enhancement. A diagnosis of "Stroke-like Migraine Attacks after Radiation Therapy" (SMART) syndrome was made. Here, we describe the brain MR spectroscopy findings of SMART, showing a decrease in N-acetyl-aspartate and increased levels of creatine and choline, corresponding with neuronal destruction or transient neuronal impairment with mild nonspecific gliosis. The absence of a lactate peak suggests that mitochondrial dysfunction, vasospasm or ischemic mechanisms were not involved.

Akinetic mutism induced by tacrolimus.

Akinetic mutism is an uncommon clinical syndrome characterized by the inability to produce voluntary movements or speech without loss of awareness. Cerebrovascular diseases are the most frequent etiology. It has been reported in cyclosporine-related neurotoxicity, but it is exceptional as the presenting form of tacrolimus intoxication. We report the case of a 66-year-old man who underwent an orthotopic liver transplantation and was treated with intravenous methylprednisolone and tacrolimus. He had an uneventful postoperative course until the third day after surgery, when he developed acute onset mutism, akinesia, and waxy rigidity of passive limb movements. His arterial blood pressure and temperature were normal. Blood analysis and a magnetic resonance image of the brain showed no acute abnormalities. Serum levels of tacrolimus were 20.8 ng/mL, so it was substituted by cyclosporine and mycophenolate mofetil with progressive and complete recovery of akinetic mutism during the following days. Akinetic mutism is an exceptional manifestation of tacrolimus neurotoxicity, but early recognition of the syndrome and withdrawal of the drug are important to avoid persistent cerebral lesions.

A new anode for solid oxide fuel cells with enhanced OCV under methane operation.

A new SOFC anode material based upon oxygen excess perovskite related phases has been synthesised. The material shows better electrochemical performance than other alternative new anodes and comparable performance to the state-of-art of the electrodes, Ni-YSZ cermets, under pure hydrogen. Furthermore, this material shows an enhanced performance under methane operation with high open circuit voltages, i.e. 1.2-1.4 V at 950 degrees C, without using steam excess. The effect of the anode configuration was tested in one and four layer configurations. The optimised electrode polarisation resistances were just 0.12 ohm cm(2) and 0.36 ohm cm(2), at 950 degrees C, in humidified H(2) and humidified CH(4), respectively. Power densities of 0.5 W cm(-2) and 0.35 W cm(-2) were obtained in the same conditions. A very low anodic overpotential of 100 mV at 1 A cm(-2) was obtained under humidified H(2) at 950 degrees C. Samples were tested for two days in reducing and oxidising conditions, alternating heating and cooling processes from 850 degrees C to 950 degrees C, showing stable electrode performance and open circuit voltages. The results show that the substituted strontium titanates are very promising anode materials for SOFC.

Synthesis, X-ray structure, polarized optical spectra and DFT theoretical calculations of two new organic-inorganic hybrid fluoromanganates(III): (bpaH2)[MnF4(H2O)2]2 and (bpeH2)[MnF4(H2O)2]2.

Two new fluoromanganates(III) of 1,2-bis(4-pyridyl)ethane (bpa) and trans-1,2-bis(4-pyridyl)ethylene (bpe), LH(2)[MnF(4)(H(2)O)(2)](2) (L = bpa or bpe), have been prepared and their structure have been solved by single-crystal X-ray diffraction. The [MnF(4)(H(2)O)(2)](-) anion displays an octahedral geometry with a strong Jahn-Teller tetragonal distortion along the H(2)O-Mn-OH(2) axis. The equatorial metal-ligand distances (Mn-F 1.827(1)-1.859(2) A) are shorter than the axial ones (Mn-O 2.203(2)-2.234(2) A). Three polarized absorption bands at 22,500, 18,300 and 14,500 cm(-1) are observed in the optical spectra of (bpaH(2))[MnF(4)(H(2)O)(2)](2). Finally, we present theoretical calculations on the equilibrium bond distances as well as the crystal-field electron structure using density functional methods. The calculated Mn-F bond distances (1.85 A) are in agreement with the experimental data but the obtained Mn-O distances (2.53-2.56 A) are higher than the experimental one as usually found in similar Jahn-Teller distorted systems. The calculated d-d transition energies are compared with experimental energies derived from the optical spectra. The variation of the HOMO energy and transition energies against the Mn-O distance is also shown.