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Improvement of properties of self-flowing low-cement castables based on brownfused alumina
Necip Ünlü,Cem Gögtas,Akln Odabasl,Levent Sezer,Filiz Çlnar,Sule Güner,Niyazi Eruslu 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5
A new self flowing brown-fused alumina based castable with 5 wt.% cement has been developed. An Andreason mathematical model (q=0.25) was used to adjust the granulometric particle size distribution. To achieve optimum self-leveling flowability, 5.6% water was used. The main physical and mechanical properties of the present castable were studied. Phase analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM) and apparent porosity (AP), bulk density (BD), water absorption (WA), cold crushing strength (CCS), hardness, and self-leveling flowability were investigated as a function of the firing temperature. The castable exhibited low AP and WA, and high CCS values with an increase in the firing temperature as a result of the corresponding phases. A new self flowing brown-fused alumina based castable with 5 wt.% cement has been developed. An Andreason mathematical model (q=0.25) was used to adjust the granulometric particle size distribution. To achieve optimum self-leveling flowability, 5.6% water was used. The main physical and mechanical properties of the present castable were studied. Phase analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM) and apparent porosity (AP), bulk density (BD), water absorption (WA), cold crushing strength (CCS), hardness, and self-leveling flowability were investigated as a function of the firing temperature. The castable exhibited low AP and WA, and high CCS values with an increase in the firing temperature as a result of the corresponding phases.
Cem Gö tas,Akln Odabasl,Levent Sezera,Filiz Çlnarb,Sule Günerc,Niyazi Eruslua,Necip Ünlü 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1
A white-fused low cement refractory castable was prepared from pure refractories that consisted of 77 wt.% white fused alumina, 10 wt.% calcined alumina, 8 wt.% microsilica, 5 wt.% cement and 0.05 wt.% dispersant. Optimum self-leveling flowability was achieved by using 5.6 wt.% water. To determine the effect of the firing temperature on the white-fused low cement refractory castable, studies of apparent porosity (AP), bulk density (BD), water absorption (WA), cold crushing strength (CCS), hardness, X-ray diffraction (XRD) and microstructural-based evaluation using electron probe microanalyser (EPMA) were performed. The present castable heat treated at 1500℃ for 2 h exhibited the following properties: the AP −14%, the BD −3.12 gcm−3, the WA −2.5%, the CCS −2000 kgcm−2 and the hardness −3185 kg㎟. The new white-fused alumina castable presents unique properties that would make it desirable to use in industrial refractory applications. A white-fused low cement refractory castable was prepared from pure refractories that consisted of 77 wt.% white fused alumina, 10 wt.% calcined alumina, 8 wt.% microsilica, 5 wt.% cement and 0.05 wt.% dispersant. Optimum self-leveling flowability was achieved by using 5.6 wt.% water. To determine the effect of the firing temperature on the white-fused low cement refractory castable, studies of apparent porosity (AP), bulk density (BD), water absorption (WA), cold crushing strength (CCS), hardness, X-ray diffraction (XRD) and microstructural-based evaluation using electron probe microanalyser (EPMA) were performed. The present castable heat treated at 1500℃ for 2 h exhibited the following properties: the AP −14%, the BD −3.12 gcm−3, the WA −2.5%, the CCS −2000 kgcm−2 and the hardness −3185 kg㎟. The new white-fused alumina castable presents unique properties that would make it desirable to use in industrial refractory applications.
The Mechanism of the Late Preconditioning Effect of 3-Nitropropionic Acid
Bilgen Basgut,Eda Aypar,Ertug Basgut,K. Okhan Akln,Nedret Klllc,And Iclal Caklcl 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.10
The aim of the present study was to investigate the mechanism of effect of 3-nitropropionic acid- (3-NP) induced late preconditioning in rat heart. For this purpose 20-30 min before 3-NP (20 mg/kg, i.p.) injection, the rats were treated intraperitoneally with 5-hydroxydecanoate (40 mg/kg, 5-HD, mitochondrial KATP-channel blocker), L-NAME (100 mg/kg, NOS inhibitor), N-2-mercaptopropionylglycine (100 mg/ kg , MPG, free radical scavenger), or superoxide dismutase+catalase (10000+10000 IU/kg , SOD+CAT). Control rats received saline only without 3-NP pretreatment. After two days, hearts were isolated and perfused at a constant pressure in a Langendorff apparatus. 15- min global ischemia followed by 30-min reperfusion was applied to all hearts. Pretreatment of 3-NP significantly reduced infarct size, creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH) levels, and incidence of ventricular tachycardia (VT) compared with the control group receiving saline only. 5-HD, L-NAME, MPG, or SOD+CAT treatment statistically reversed 3-NP-induced reduction in infarct size. Although CK-MB, LDH levels, and incidence of VT were also reduced by L-NAME, MPG, or SOD+CAT treatment, only 5-HD significantly inhibited beneficial effects of 3-NP on all of the parameters above. These results showed that mito-KATP channels play a pivotal role in late preconditioning effect of 3-NP in the isolated rat heart. However, other mediators such as reactive oxygen species and NO may be, at least in part, involved in mechanisms of this effect.