Electrooxidation of methanol in sulfuric acid solution was studied using Pt, Pt/Ni(1:1 and 3:1), Pt/Ru/Ni(5: 4:1 and 6:3.5:0.5), and Pt/Ru(1:1) alloy nanoparticle catalysts, in relation to methanol oxidation processes in the direct oxidation methanol fuel cell. The Pt/Ni and Pt/Ru/Ni alloys showed excellent catalytic activities compared to those of pure Pt and Pt/Ru. The role of Ni as a catalytically enhancing agent in the oxidation process was interrogated using cyclic voltammetry, chronoamperometry, X-ray photoelectron spectroscopy, transmission electron microscopy, and X-ray diffraction. X-ray diffraction data showed alloy formation for all Pt/Ni, Pt/Ru/Ni, and Pt/Ru nanoparticles, whereas X-ray photoelectron spectroscopy confirmed that chemical states of Pt were exclusively metallic. The presence of metallic Ni, NiO, Ni(OH) 2 , NiOOH, metallic Ru, RuO 2 , and RuO 3 was also confirmed. We found that the Pt4f binding energies for the Pt/Ni and Pt/Ru/Ni alloy nanoparticles were lower than those for clean Pt nanoparticles. The oxides that serve as the oxygen donors for the oxidation process, and the change in the electronic structure of the Pt component in the alloys versus those in Pt and Pt/Ru collectively account, we believe, for enhancement in rates of methanol oxidation. The difference in the peak shift in Pt4f between Pt/Ni and Pt/Ru alloy nanoparticles is discussed by using electronegativities of the three components: Pt, Ru, and Ni. A comparison between the alloy nanoparticle composition and that of disk alloy electrodes under similar conditions was made in terms of the surface-tovolume ratio and surface segregation of the alloying components.

Background and Purpose-Diagnosis of Moyamoya disease (MMD) is based on the characteristic angiographic findings.However, differentiating MMD from intracranial atherosclerotic disease (ICAD) is difficult. We compared vessel wall imaging findings on high-resolution magnetic resonance imaging between MMD and ICAD. Methods-High-resolution magnetic resonance imaging was performed on 32 patients with angiographically proven MMD and 16 patients with acute infarcts because of ICAD. Bilateral internal carotid arteries and steno-occlusive middle cerebral artery were analyzed for wall enhancement and remodeling. Results-Enhancement patterns and distribution were different. Most patients with MMD (90.6%) showed concentric enhancement on distal internal carotid arteries and middle cerebral arteries, whereas focal eccentric enhancement was observed on the symptomatic segment in ICAD. MMD was characterized by middle cerebral artery shrinkage; the remodeling index and wall area were lower in MMD than in ICAD (remodeling index, 0.19±0.11 versus 1.00±0.43; wall area, 0.32±0.22 versus 6.00±2.72; P<0.001). Conclusions-MMD

Summary: Purpose: To assess the magnetic resonance imaging (MRI), positron emission tomography (PET), pathology, and clinical findings of patients with the MRI feature of whitematter change (WMC) in the anterior temporal lobe.Methods: Fifty-six patients with pathologically proven mesial temporal sclerosis were included in this study. MRI and F-2-deoxyglucose-(FDG) PET images were obtained before in surgery in all patients. The patients were divided into two groups according to the presence of WMC on their MRI. WMC consists of an indistinct gray-white matter demarcation and an increased signal intensity of the anterior temporal lobe on T,-weighted images. The two groups were then compared in terms of MRI, PET, pathology, and clinical features.Results: The MRI feature of WMC was observed in 18 (32%) of the 56 patients. PET images of those patients revealed more severe hypometabolism of the ipsilateral temporal lobes (p < 0.05). In terms of histologic findings, larger numbers of heterotopic neurons were observed in the anterior temporal lobe white matter of these patients who also shared the following clinical features: earlier seizure onset, frequent history of febrile convulsions, and favorable surgical outcomes.Conclusions: The MRI feature of WMC is an additive sign for correct seizure lateralization and may be related to a favorable surgical outcome in patients with temporal lobe epilepsy. Key Words: Mesial temporal sclerosis-Epilepsy-Magnetic resonance imaging-Positron emission tomography-White matter change.Atrophy and signal changes of the hippocampus have been known as the most reliable magnetic resonance imaging (MRI) criteria of mesial temporal sclerosis ( 1 4 ) . One MRI feature of mesial temporal sclerosis is whitematter change (WMC) in the anterior temporal lobe. This change consists of an indistinct gray-white matter demarcation with increased signal intensity on T,-weighted images (1,2,5-13). Previous pathologic studies (2,9,10, 12-17) conducted on tissue obtained after temporal lobectomies revealed abnormal histologic changes in the white matter of the ipsilateral temporal lobe in patients with intractable temporal lobe epilepsy (TLE). However, the pathologic documentation of WMC on MRIs has not been fully performed, and the clinical significance has not been established.The purpose of this study was to assess the MRI, pos- hsbyun@smc.samsung.co.kr itron emission tomography (PET), pathology, and clinical findings of patients with WMC. We also attempted to determine the value of this MRI feature for the presurgical lateralizaton of the epileptic focus and the surgical outcome in patients with mesial temporal sclerosis. METHODSFrom January 1995 to February 1997, 58 consecutive patients with TLE were surgically proven to have mesial temporal sclerosis. Two cases that were concomitant with focal cortical dysplasia were excluded from this study, with the remained 56 included. The study group consisted of 31 men and 25 women with a mean age of 28 years (range, 13-44 years). All patients underwent an ante...