In some industrial plants, wastewater was intermittently or seasonally generated. There may be periods during which wastewater treatment facilities have to be set into an idle phase over several weeks. When wastewater...In some industrial plants, wastewater was intermittently or seasonally generated. There may be periods during which wastewater treatment facilities have to be set into an idle phase over several weeks. When wastewater was generated again, the activated sludge flocs may have disintegrated. In this experiment, re-activation characteristics of aerobic granular sludge starved for 2 months were investigated. Specific oxygen utilization rate(SOUR) was used as an indicator to evaluate the metabolic activity of the sludge. The results revealed that aerobic granular sludge could be stored up to two months without running the risk of losing the integrity of the granules and metabolic potentials. The apparent color of aerobic granules stored at room temperature gradually turned from brownish-yellowish to gray brown. They appeared brownish-yellowish again 2 weeks after re-activation. The velocity and strength of granules after 2-month idle period could be fully restored about 3 weeks after re-activation. Metabolic activity, however, dropped to 15 8 mg O_2/(g MLVSS·h), i.e. 74 % reduction after 2 months of storage. After restarting the reactor, it took 2 weeks that SOUR of up to 48 5 mg O_2 /(g MLVSS·h) was achieved. A stable effluent COD concentration of less than 150 mg/L was achieved during the re-activation process.展开更多
Molecular virology methods including polymerase chain reaction, cloning and sequencing have revolutionised our understanding of viral genome variation. In the case of hepatitis B virus (HBV), sequencing studies have i...Molecular virology methods including polymerase chain reaction, cloning and sequencing have revolutionised our understanding of viral genome variation. In the case of hepatitis B virus (HBV), sequencing studies have identified a number of virus variants normally found during the natural course of chronic infection. The appearance of the precore stop codon (with G-for-A substitution at position 1896) and basal core promoter (BCP) (with A-for-T and G-for-A, at positions 1762 and 1764, respectively) variants which reduce or abrogate hepatitis B e antigen (HBeAg) production, heralds the initiation of the seroconversion phase from HBeAg to anti-HBe positivity. The gradual removal of the tolerogenic effect of HBeAg leads to the awakening of the immune response (immune clearance phase). Most patients after HBeAg seroconversion become “inactive HBsAg carriers”. However during the course of infection precore and/or BCP variants may emerge and be selected leading to HBeAg negative chronic hepatitis B (CHB) with high viremia levels (reactivation phase). The prevalence of HBeAg negative CHB has been increasing over the last few decades and has become the commonest type of HBV infection in many countries of the world. This probably reflects the aging of existing HBV carriers and the effective prevention measures restricting new HBV infections. Frequent acute exacerbations accompanied by high viral replication, elevated alanine aminotransferase levels and histological activity are a common feature of HBeAg negative CHB leading to cirrhosis much faster than in HBeAg positive CHB patients.展开更多
Among the inherent drawbacks of conducting polymers are the limited processibility, uneven polydispersity inmolecular weigh and the existence of structure defects, which become the obstacles for many electronic, optic...Among the inherent drawbacks of conducting polymers are the limited processibility, uneven polydispersity inmolecular weigh and the existence of structure defects, which become the obstacles for many electronic, optical andbiological applications that demand the materials to have well-defined structures and high chemical purity. To solve theseproblems, our research in the last decade or so has focused on the synthesis of electroactive oligomers of well-definedstructures, controllable molecular weighs, narrow or uniform polydispersity. We have developed a general strategy for thesynthesis of such oligomers based on the theory of non-classical or reactivation chain polymerization. The aniline oligomerswith minimum 4 nitrogen atoms and 3 phenylene rings exhibit similar characteristic redox behavior and electroactivity aspolyaniline. Electronic conductivity of the oligomers of 7 or 8 aniline units approaches that of polyaniline. Solubility of theoligomers is much improved over that of conventional polyaniline. Various functional groups can be introduced into theoligomers either by proper selection of starting materials or by post-synthesis modifications via common organic reactions.The functionalized oligomers undergo further polymerizations to afford a variety of new electroactive materials, includingpolyamides, polyimides, polyureas, polyurethanes, polyacrylamides and epoxy polymers. Numerous potential applications,particularly as anticorrosion materials, are discussed for the oligomers and their polymeric derivatives.展开更多
文摘In some industrial plants, wastewater was intermittently or seasonally generated. There may be periods during which wastewater treatment facilities have to be set into an idle phase over several weeks. When wastewater was generated again, the activated sludge flocs may have disintegrated. In this experiment, re-activation characteristics of aerobic granular sludge starved for 2 months were investigated. Specific oxygen utilization rate(SOUR) was used as an indicator to evaluate the metabolic activity of the sludge. The results revealed that aerobic granular sludge could be stored up to two months without running the risk of losing the integrity of the granules and metabolic potentials. The apparent color of aerobic granules stored at room temperature gradually turned from brownish-yellowish to gray brown. They appeared brownish-yellowish again 2 weeks after re-activation. The velocity and strength of granules after 2-month idle period could be fully restored about 3 weeks after re-activation. Metabolic activity, however, dropped to 15 8 mg O_2/(g MLVSS·h), i.e. 74 % reduction after 2 months of storage. After restarting the reactor, it took 2 weeks that SOUR of up to 48 5 mg O_2 /(g MLVSS·h) was achieved. A stable effluent COD concentration of less than 150 mg/L was achieved during the re-activation process.
文摘Molecular virology methods including polymerase chain reaction, cloning and sequencing have revolutionised our understanding of viral genome variation. In the case of hepatitis B virus (HBV), sequencing studies have identified a number of virus variants normally found during the natural course of chronic infection. The appearance of the precore stop codon (with G-for-A substitution at position 1896) and basal core promoter (BCP) (with A-for-T and G-for-A, at positions 1762 and 1764, respectively) variants which reduce or abrogate hepatitis B e antigen (HBeAg) production, heralds the initiation of the seroconversion phase from HBeAg to anti-HBe positivity. The gradual removal of the tolerogenic effect of HBeAg leads to the awakening of the immune response (immune clearance phase). Most patients after HBeAg seroconversion become “inactive HBsAg carriers”. However during the course of infection precore and/or BCP variants may emerge and be selected leading to HBeAg negative chronic hepatitis B (CHB) with high viremia levels (reactivation phase). The prevalence of HBeAg negative CHB has been increasing over the last few decades and has become the commonest type of HBV infection in many countries of the world. This probably reflects the aging of existing HBV carriers and the effective prevention measures restricting new HBV infections. Frequent acute exacerbations accompanied by high viral replication, elevated alanine aminotransferase levels and histological activity are a common feature of HBeAg negative CHB leading to cirrhosis much faster than in HBeAg positive CHB patients.
文摘Among the inherent drawbacks of conducting polymers are the limited processibility, uneven polydispersity inmolecular weigh and the existence of structure defects, which become the obstacles for many electronic, optical andbiological applications that demand the materials to have well-defined structures and high chemical purity. To solve theseproblems, our research in the last decade or so has focused on the synthesis of electroactive oligomers of well-definedstructures, controllable molecular weighs, narrow or uniform polydispersity. We have developed a general strategy for thesynthesis of such oligomers based on the theory of non-classical or reactivation chain polymerization. The aniline oligomerswith minimum 4 nitrogen atoms and 3 phenylene rings exhibit similar characteristic redox behavior and electroactivity aspolyaniline. Electronic conductivity of the oligomers of 7 or 8 aniline units approaches that of polyaniline. Solubility of theoligomers is much improved over that of conventional polyaniline. Various functional groups can be introduced into theoligomers either by proper selection of starting materials or by post-synthesis modifications via common organic reactions.The functionalized oligomers undergo further polymerizations to afford a variety of new electroactive materials, includingpolyamides, polyimides, polyureas, polyurethanes, polyacrylamides and epoxy polymers. Numerous potential applications,particularly as anticorrosion materials, are discussed for the oligomers and their polymeric derivatives.
