Search

Nb promoter was introduced in the Co–CeO2 catalyst to improve its catalytic performance in the high temperature water gas shift (HT-WGS) reaction, which involves the production of hydrogen from waste-derived synthesis gas. Thereafter, the physicochemical properties of the promoter as well as those of the catalyst were investigated using various techniques. Thus, it was confirmed that the Nb promoter affects the key properties related to catalytic performance, including oxygen storage capacity (OSC) and dispersion. To maximize the positive effect of the Nb promoter, we further investigated the effect of the Nb loading amount on the performance of the catalyst. The results obtained showed that the 1.5NbCo catalyst exhibited the highest catalytic performance (XCO = 89% at 450 °C) under very severe conditions (gas hourly space velocity (GHSV) = 637,320 h−1). Additionally, this catalyst exhibited stable activity for 50 h. This its high catalytic performance could be attributed to its high OSC and Co dispersion. Therefore, it is a promising catalyst for hydrogen production via the HT-WGS reaction.

The water–gas shift (WGS) reaction has been attracting interest for on-site small-scale production of hydrogen. This study discusses the fabrication of inexpensive, high-performance Cu/CeO2 catalysts. To synthesize these catalysts, CeO2 supports were prepared using K2CO3/KOH as precipitants in different ratios. First, 20 wt% Cu was loaded onto the prepared CeO2 supports through incipient wetness impregnation. The ratios of the precipitants affect the physicochemical properties of the Cu/CeO2 catalysts, which in turn affects the catalytic performance. On increasing the K2CO3/KOH ratio, the surface area, oxygen storage capacity, and reducibility increased, while Cu dispersion decreased. To achieve high activity of Cu/CeO2 catalysts, the CeO2 support should be synthesized at the K2CO3 : KOH ratio of 3 : 1. This Cu/CeO2 catalyst exhibits the highest CO conversion between 200 and 400 °C, even at a very high gas hourly specific velocity of 50 102 h−1. This result shows that the catalytic performance is greatly influenced by various physicochemical properties such as surface area, oxygen storage capacity, Cu dispersion, and reducibility.

Purpose: The aim of this study was to analyze the imaging findings and clinical characteristics of extratendinous migration of calcific tendinitis of the shoulder with temporal changes.Methods: Seventy-six patients with extratendinous calcific tendinitis of the shoulder diagnosed by ultrasonography (US) or magnetic resonance imaging (MRI) were enrolled in this retrospective study. Clinical symptoms and imaging findings (on radiography, US, and MRI) of extratendinous calcific tendinitis during an acute painful attack were analyzed. Temporal changes were analyzed in 28 patients before an acute attack and 40 patients after an acute attack. For comparison, 65 patients with intratendinous calcific tendinitis were included.Results: Patients with extratendinous calcific tendinitis had a significantly higher average visual analogue scale (VAS) score (8.8±1.6) than the intratendinous group (6.4±2.2) (P

The effect of Nb promotion over a Cu–CeO2 catalyst was investigated in the low-temperature water gas shift reaction. The Nb loading amount was systematically varied from 0 to 5 wt% for the Cu–Nb–CeO2 catalyst, and the 1 wt% Nb promoted Cu–Nb–CeO2 catalyst exhibited the highest catalytic performance even at extremely high GHSV of 72,152 h−1. The catalysts were characterized through various techniques such as Brunauer-Emmet-Teller measurements, X-ray diffraction, N2O-chemisorption, H2-temperature programmed reduction, X-ray photoelectron spectroscopy, and transmission electron microscopy. It was found that the superior performance of the 1 wt% Nb promoted Cu–Nb–CeO2 catalyst was due to its enhanced reducibility, high BET surface area, small metallic Cu crystallite size, and high number of oxygen vacancies.

The objective of this research is to evaluate optimal conditions of permeability and selectivity on the polysulfone membrane for efficiency of separation of CH 4 by checking four factors which are temperature, pressure, gas compositions and gas flow rates. When higher pressure was applied at the input, lower efficiency of recovery of CH 4 and higher efficiency of separation of CH 4 were shown. It has the tendency to show lower efficiency of recovery of CH 4 and higher efficiency of separation of CH 4 at the output as higher temperature at input. The lower flow rates make higher efficiency of recovery of CH 4 and lower efficiency of separation of CH 4 . Finally, over 90% efficiency for CH 4 separation and recovery conditions are temperature (-5℃), pressure (8 bar), gas composition rate (6:4) (CH 4 :CO 2 ) and gas flow rate (5 l/min). These conditions make higher separation and recovery efficiency such as 90.1% and 92.1%, respectively. Key Words : Biogas, CH 4 concentration, Recovery efficiency, Green house effect

Background Autologous periosteal grafting is used as treatment for cartilage defects. Purpose To assess the role of MR imaging and ultrasonography in the evaluation of the post-graft repair process with imaging and histologic correlation. Material and Methods Periosteal grafts obtained from the tibia of eight dogs were transplanted to the experimental cartilage defects in the femoral condyles (15 knees). The control group was comprised of three dogs (five knees). MR imaging using 4.7T and ultrasonography of the grafted specimens was performed at one, two, four, eight, and 16 weeks after transplantation. The animals were sacrificed at the time of imaging at the previously specified intervals. Histologic analysis with imaging correlation was subsequently performed. Results All specimens taken from one to 16 weeks demonstrated periosteal proliferation in the graft. At one week, experimental cartilage defects were no longer present on MR imaging. Area of high signal intensity (SI) in the defect was present which corresponded to hemorrhage, edema, and fibrosis on histology. At two, four, and eight weeks, all but two graft demonstrated heterogeneous high SI on T2-weighted image, consistent with immature cartilage. At 16 weeks, all grafts showed heterogeneous isointense to adjacent cartilage on all sequences, which corresponded to dominant mature cartilage. The repair tissue near the exposed subchondral bone revealed heterogeneous high SI on T2-weighted images. This corresponded to the fibrosis with vascular penetration and edema. In the control group, no cartilage repair was noted within cartilage defects. The serial MR features of the grafted area correlated well with the histologic findings. Serial sonographic findings were not sufficient to provide the regenerated cartilage maturity. Conclusion MR imaging is capable of depicting the repair characteristics following periosteal grafting for articular cartilage defects. MR imaging may provide useful information in the assessment of the graft appearance with definite implications regarding the degree and success of incorporation.

Lumbar intervertebal disc herniation is common in the fourth to fifth decades because the intervertebral disc undergoes degenerative change. However juvenile lumbar intervertebal disc herniation (under 12 years old) is rare because there is no degenerative change, and the clinical symptoms and treatments are different from those of adults. Herein, our experience of five juvenile lumbar intervertebal disc herniation cases are analyzed and reported.

Purpose: To evaluate the clinical features and treatment of ganglion cyst of the hallux. Materials and Methods: From August 1990 to December 2002, seven patients with a ganglion cyst of the hallux were treated. Six cases underwent surgical excision and one repeated aspiration. Results: Four cases showed recurrence after the initial surgical excision. Characteristics of the ganglion cyst of the hallux were; (1) mass accompanied by pain, (2) frequent recurrence after surgical excision, and (3) frequent communication with a joint. In one case of ganglion communicating with the interphalangeal joint, the joint of the involved hallux was finally fused due to repeated recurrence. Conclusion: Ganglion cyst of the great toe needs to be evaluated by specialized study such as MRI for joint comminucation, and treated by meticulous surgical excision to prevent recurrence.

Purpose : In this study, we investigated the magnetic resonance (MR) imaging characteristics of rapidly destructive coxarthrosis (RDC) caused by osteonecrosis of the femoral head. Material and Method : We reviewed 11 hip MR images (10 patients) of osteonecrosis of the femoral head with RDC. MR findings of 11 RDC were compared with those of Ficat stage IV osteonecrosis of the femoral head as a control. Results : The MR findings of osteonecrosis, involving the entire femoral head, bone marrow edema in the acetabulum, intraarticular loose bodies on the inferomedial portion of the hip joint, and synovial proliferation were significant in RDC as compared with those of osteonecrosis of the femoral head only. Conclusion : Distinct findings of MR imaging in conjunction with plain radiographs could be used to facilitate diagnosis, treatment, and prognosis in RDC.