In this paper, methylmethacrylate-acrylic acid MMA-AA hydrophilic and hydrophobic copolymers were prepared by copolymerization for preparing membrane materials. The composite membrane of cellulose acetate (CA) blended...In this paper, methylmethacrylate-acrylic acid MMA-AA hydrophilic and hydrophobic copolymers were prepared by copolymerization for preparing membrane materials. The composite membrane of cellulose acetate (CA) blended with MMA-AA hydrophobic copolymer was used for the separation of methanol from pentane-methanol mixture. When the methanol concentration was only 1 wt%, the permeate flux still maintained at 350 g/m(2)h and separation factor was as big as 800. The composite membrane of PVA (polyvinyl alcohol) blended with MMA-AA hydrophilic copolymer was used for the separation of ethanol-water mixture. The permeate flux was increased to 975 g/m(2)h at 74 degrees C and the separation factor reached 3000 at 25 degrees C. The PVA/MMA-AA blended membrane surface modified by ammonia plasma was also investigated for separating ethanol-water mixture. Both permeate flux and separation factor of the membrane was improved. However, there was no obvious difference of plasma treatment time in the interval of 20 similar to 40 min.展开更多
There are two subtypes of hepatitis B virus genotype A (HBV/ A) and they are p rovisionally designated Aa (“a”standing for Africa/Asia) and Ae (“e”for Euro pe). In a case-control study, 78 HBV/Aa, 78HBV/Ae, and 78...There are two subtypes of hepatitis B virus genotype A (HBV/ A) and they are p rovisionally designated Aa (“a”standing for Africa/Asia) and Ae (“e”for Euro pe). In a case-control study, 78 HBV/Aa, 78HBV/Ae, and 78HBV/D carriers from several co untries were compared. The prevalence of HBe antigen (HBeAg) in serum was signif icantly lower in carriers of HBV/Aa than in carriers of HBV/Ae (31%vs. 49%; P = .033), with a difference more obvious in the carriers aged 30 years or younger (34%vs. 67%; P = .029). HBV DNA levels in the carriers of HBV/Aa (median, 3.4 6 log copies/mL; 95%CI, 2.93-3.95)were significantly lower than those of carri ers of HBV/Ae (6.09 log copies/mL; 95%CI, 4.24-7.64) or of carriers ofHBV/D (5 .48 log copies/mL; 95%CI, 4.06-7.02), regardless of the HBeAg status (P< .001) . The most specific and frequent substitutions in 54 HBV/Aa isolates were double substitutions for T1809 (100%) and T1812 (96%) immediately upstream of the pr ecore initiation codon, which would interfere with the translation of HBeAg in H BV/Aa infections. They were not detected in 57 HBV/Ae or 61 HBV/D isolates exami ned. The double mutation in the core promoter (T1762/A1764)was more frequent in both HBV/Aa (50%) and HBV/Ae (44%) than in HBV/D isolates (25%; P< .01), wher eas the precore mutation (A1896) occurred in HBV/D isolates only (48%; P < .000 1). In conclusion, the clearance of HBeAg from serum may occur by different mec hanisms in HBV/Aa, HBV/Ae, and HBV/D infections, which may influence clinical ma nifestations in the Western countries where both genotypes A and D are prevalent .展开更多
基金The key project is supported by the National Natural Science Foundation of China(No.29836160).
文摘In this paper, methylmethacrylate-acrylic acid MMA-AA hydrophilic and hydrophobic copolymers were prepared by copolymerization for preparing membrane materials. The composite membrane of cellulose acetate (CA) blended with MMA-AA hydrophobic copolymer was used for the separation of methanol from pentane-methanol mixture. When the methanol concentration was only 1 wt%, the permeate flux still maintained at 350 g/m(2)h and separation factor was as big as 800. The composite membrane of PVA (polyvinyl alcohol) blended with MMA-AA hydrophilic copolymer was used for the separation of ethanol-water mixture. The permeate flux was increased to 975 g/m(2)h at 74 degrees C and the separation factor reached 3000 at 25 degrees C. The PVA/MMA-AA blended membrane surface modified by ammonia plasma was also investigated for separating ethanol-water mixture. Both permeate flux and separation factor of the membrane was improved. However, there was no obvious difference of plasma treatment time in the interval of 20 similar to 40 min.
文摘There are two subtypes of hepatitis B virus genotype A (HBV/ A) and they are p rovisionally designated Aa (“a”standing for Africa/Asia) and Ae (“e”for Euro pe). In a case-control study, 78 HBV/Aa, 78HBV/Ae, and 78HBV/D carriers from several co untries were compared. The prevalence of HBe antigen (HBeAg) in serum was signif icantly lower in carriers of HBV/Aa than in carriers of HBV/Ae (31%vs. 49%; P = .033), with a difference more obvious in the carriers aged 30 years or younger (34%vs. 67%; P = .029). HBV DNA levels in the carriers of HBV/Aa (median, 3.4 6 log copies/mL; 95%CI, 2.93-3.95)were significantly lower than those of carri ers of HBV/Ae (6.09 log copies/mL; 95%CI, 4.24-7.64) or of carriers ofHBV/D (5 .48 log copies/mL; 95%CI, 4.06-7.02), regardless of the HBeAg status (P< .001) . The most specific and frequent substitutions in 54 HBV/Aa isolates were double substitutions for T1809 (100%) and T1812 (96%) immediately upstream of the pr ecore initiation codon, which would interfere with the translation of HBeAg in H BV/Aa infections. They were not detected in 57 HBV/Ae or 61 HBV/D isolates exami ned. The double mutation in the core promoter (T1762/A1764)was more frequent in both HBV/Aa (50%) and HBV/Ae (44%) than in HBV/D isolates (25%; P< .01), wher eas the precore mutation (A1896) occurred in HBV/D isolates only (48%; P < .000 1). In conclusion, the clearance of HBeAg from serum may occur by different mec hanisms in HBV/Aa, HBV/Ae, and HBV/D infections, which may influence clinical ma nifestations in the Western countries where both genotypes A and D are prevalent .
