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A Laboratory-scale experiment was conducted to investigate the influence of organic loading rate to a reactor on the bio fouling in a membrane separation activated sludge system. A flat-sheet-type membrane module was used and the change of the pressure and the filtration resistance were measured. Using synthetic substrate, TOC loading rate was set in the range between 0.3 g l–1 day–1 and 1.5g l–1 day–1. Also an experiment on the consolidation characteristics of sludge accumulated on membrane was conducted. A mathematical model was developed to simulate temporal changes of suction pressure, flux and filtration resistance considering accumulation, detachment and consolidation of bacterial extracellular polymers on the membrane surface. A reactor with higher loading rate showed sudden increase of trans-membrane pressure, while a reactor with lower loading rate showed delayed increase of the pressure. The experimental results were simulated well by the developed model.

SYNOPSISPhotografting of N-isopropylacrylamide ( NIPAAm) on ethylene-vinyl alcohol copolymer films (thickness = 15,20, and 25 Fm) and low-and high-density polyethylene films (thickness = 30 pm) was carried out at 60°C in a water medium. Xanthone was used as a photoinitiator by coating it on the film samples. The resultant NIPAAm-grafted films exhibited a temperature-responsive character, which was evaluated by measuring a dimensional change of the grafted films. The grafted films swelled and shrank in water at temperatures lower and higher than around 30"C, respectively. The character was found to be reversible between 0 and 50°C. It was observed that the extent of the character is largely influenced by film thickness, location of NIPAAm-grafted chains, and crystallinity of film substrate. 0 1994

SUMMARYPrevention of restenosis after percutaneous transluminal coronary angioplasty (PTCA) continues to be a significant problem. Recent controlled studies have demonstrated that cilostazol suppresses restenosis after PTCA. The effects of ticlopidine, another antiplatelet agent, were compared in terms of outcomes of patients randomized for treatment with the two drugs after PTCA. A total of 35 patients (47 lesions) were assigned prospectively and randomly to ticlopidine (17 patients, 24 lesions) and cilostazol (18 patients, 23 lesions) groups. Minimal luminal diameter (MLD) and percentage of stenosis to reference diameter were estimated before PTCA, just after the procedure and after 4 months follow-up. All patients underwent 4 months angiographic follow-up, at the end of which MLD was 2.03 ± 0.71 mm in the ticlopidine group and 2.05 ± 0.68 mm in the cilostazol group (p = 0.95), and the percentage of stenosis to reference diameter was 31.4 ± 16.7% and 30.0 ± 17.0%, respectively (p = 0.78). The restenosis rate was 12.5% in the ticlopidine group and 17.4% in the cilostazol group (p = 0.69), relatively low as compared to the 20% to 30% reported in previous studies. Adverse drug reactions during the followup period were observed in two of the ticlopidine group and none of the cilostazol group. We conclude that both ticlopidine and cilostazol are effective for the prevention of restenosis after PTCA, however the former may be associated with slight side effects. (Jpn Heart J 2001; 42: 43-54) Key words: Antiplatelet therapy, Follow-up studies, Quantitative coronary arteriography RESTENOSIS after percutaneous transluminal coronary angioplasty (PTCA) is still a major limitation to long-term successful therapy. Coronary stent implantation is associated with a significant reduction in the angiographic restenosis rate compared with conventional simple balloon angioplasty, with decreases to 20% to 30% reported by the BENESTENT 1) and STRESS 2) trials, but the search for