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Effect of Activator on Hydrogen Peroxide Bleaching of White Ledger
Sakai, Kokki,Kondo, Ryuichiro,Ahn, Byoung Jun,Paik, Ki Hyon 한국공업화학회 2001 Journal of Industrial and Engineering Chemistry Vol.7 No.5
The effectiveness of novel activators in the hydrogen peroxide bleaching of white ledger was investigated. With the addition of 1% sodium persulfate, 4% Prestogen EB, and thiourea(molar ratio to residual hydrogen peroxide=1/2) to hydrogen peroxide bleaching, the brightness of the bleached pulps increased by up to 2∼3 points when compared to hydrogen peroxide bleaching with conventional activators. The effectiveness of the activators in enhancing the brightness was in the order of Prestogen EB, thioruea, sodium persulfate and silicates. The strengths of the pulps bleached by hydrogen peroxide with the novel activators were slightly lower or similar to those of the pulps bleached by conventional hydrogen peroxide. In particular, the addition of sodium persulfate produced a more marked decrease in the tensile index of the bleached pulp. Accordingly, sequential oxidative and reductive bleaching with the addition of thiourea to the residual hydrogen peroxide was found to be most effective in view of th bleaching chemical cost, brightness gains, and strength of the bleached pulps.
Some Properties of Xanthine Dehydrogenase from Pseudomonas synxantha A3
Jun, Hong Ki,Takuo, Sakai 한국산업미생물학회 1991 한국미생물·생명공학회지 Vol.19 No.6
Pseudomonas synxantha A3로부터 정제된 결정화 효소를 사용하여 몇가지의 성질을 검토하였다. 본 효소에 대한 nucleoside 관련물질의 저해관계를 검토한 결과, 그 중에서 adenine, 8-azaadenine, 2-methyladeine, guanine, 8-azaguanine에 의해서 강한 저해를 받는 것으로 나타났으며, caffenine에 의해서는 저해를 받지 않았다. Adenine과 guanine은 비길항저해제로서, 그 저해상수(K_i)는 각각 0.037mM과 0.098mM이었다. 그리고 pH8.5에 있어서 hypoxanthine과 NAD^+에 대한 K_m값은 각각 0.33mM, 0.1mM이며, 또한 xanthine과 NAD^+에 대한 K_m값은 각각 0.06mM, 0.1mM이었다. Some of the Kinetic properties of crystallic xanthine dehydrogenase form Pseudomonas synxantha A3 were studied. The enzyme activity was strongly inhibited by adenine, 8-azaadenine, 2-methyladenine, guanine, and 8-azaguanine, but not by caffeine, and the inhibitions by adenine and guanine were observed to be of noncompetitive type. The K_i values for adenine and guanine were 0.037 and 0.098 mM, respectively. Michaelis constants were found to be 0.33 and 0.06 mM for hypoxanthine and xanthine with NAD^+ as the second substrate, respectively, and 0.1mM for NAD^+ with either hypoxanthine or xanthine as the second substrate.
Park, Jun Seok,Sakai, Yoshiharu,Simon, NG Siu Man,Law, Wai Lun,Kim, Hyeong Rok,Oh, Jae Hwan,Shan, Hester Cheung Yui,Kwak, Sang Gyu,Choi, Gyu-Seog Wolters Kluwer Health, Inc. All rights reserved. 2016 Medicine Vol.95 No.22
<P>Controversy remains regarding whether preoperative chemoradiation protocol should be applied uniformly to all rectal cancer patients regardless of tumor height. This pooled analysis was designed to evaluate whether preoperative chemoradiation can be safely omitted in higher rectal cancer. An international consortium of 7 institutions was established. A review of the database that was collected from January 2004 to May 2008 identified a series of 2102 patients with stage II/III rectal or sigmoid cancer (control arm) without concurrent chemoradiation. Data regarding patient demographics, recurrence pattern, and oncological outcomes were analyzed. The primary end point was the 5-year local recurrence rate. The local relapse rate of the sigmoid colon cancer (SC) and upper rectal cancer (UR) cohorts was significantly lower than that of the mid/low rectal cancer group (M-LR), with 5-year estimates of 2.5% for the SC group, 3.5% for the UR group, and 11.1% for the M-LR group, respectively. A multivariate analysis showed that tumor depth, nodal metastasis, venous invasion, and lower tumor level were strongly associated with local recurrence. The cumulative incidence rate of local failure was 90.6%, 92.5%, and 94.4% for tumors located within 5, 7, and 9 cm from the anal verge, respectively. Routine use of preoperative chemoradiation for stage II/III rectal tumors located more than 8 to 9 cm above the anal verge would be excessive. The integration of a more individualized approach focused on systemic control is warranted to improve survival in patients with upper rectal cancer.</P>