[Improvement of the Dewaterability of Excess Activated Sludge with Mixed Yeasts by Degrading Extracellular Polymeric Substances].

The dewaterability of excess sludge directly affects the efficiency and cost of sludge disposal, and improving sludge dewaterability is a crucial way to reduce sludge volume. This study proposes a method to improve the dewaterability of residual sludge by using mixed yeast strains to degrade extracellular polymeric substances (EPS) in activated sludge. Firstly, the mixed cells of three yeast strains were injected into the sterilized EPS solution to investigate the degradation efficiency of EPS components. Secondly, the mixed yeast cells were supplied into the residual sludge, which was aerated for several hours while the sludge dewaterability was evaluated. The results showed that the degradation efficiencies of yeast to proteins, polysaccharides, and nucleic acids in EPS were evident, and reductions of (60.43±2.73)%, (18.94±2.39)%, and (48.30±3.37)% were achieved, respectively, within 72 hours' oscillating cultivation. The capillary suction time (CST) of the sludge decreased by (17.19±1.16)% after aeration, with 1.5 g mixed yeast wet cells added into 2 L excess sludge, (7.03±1.35)% more than that of the control test after 24 hours. Meanwhile, the total amount of EPS in sludge decreased by (17.46±3.91)% more than that in the control sludge, indicating that the yeast can improve the sludge dewaterability in-situ by degrading EPS in sludge.

Association of apolipoprotein E 4 polymorphism with cerebral infarction in Chinese Han population.

AIM: To study the association between APOE polymorphisms and cerebral infarction through a case-control study among the Chinese Han population. METHODS: First-ever cerebral infarction patients (n=226) whose ages ranged from 40 to 60 years old were recruited from Department of Neurology, Zhongshan Hospital, Shanghai, and Zhejiang Chinese Traditional Medicine Hospital, Zhejiang, China. Unrelated healthy controls (n=201) were selected from the general population in the same area with similar age and sex distribution. APOE was amplified by one-stage PCR using the forward primer: 5'-GGC ACG GCT GTC CAA GGA GCT-3' and reverse primer: 5'-GAT GGC GCT GAG GCC GCG CT-3'. The PCR product was digested directly with 5 U of CfoI and separated by a 20 % polyacrylamide (acrylamide: bis-acrylamide=29:1) nondenaturing gel. RESULTS: Both cerebral infarction patient and control groups were in Hardy-Weinberg equilibrium. The allele frequency of APOE*2, APOE*3, and APOE*4 was 4.6 %, 81.9 %, and 13.5 % respectively in the patients with cerebral infarction; 5.7 %, 87.3 %, and 7.0 % respectively in the healthy control group. Compared with APOE3/3 subjects, APOE4/4 carriers had a 2.1-fold risk of cerebral infarction (odds ratio 2.1, 95 % confidence limits 1.3 to 3.4). The allele frequency of APOE*4 in the cerebral infarction patient group was significantly higher than that in the control group (13.5 % vs 7.0 %; P=0.002). CONCLUSION: APOE 4 is a risk factor for cerebral infarction among the Chinese Han population.