疾病知识、医疗文化与卫生现代性 : 近代中国肺结核病的社会与文化史(1850-1940年代) = Tuberculosis in modern China: A social and cultural history (1850-1940s)

Ph.DDOCTOR OF PHILOSOPH

Prokaryotic community structures in biogas plants with swine manure

采集了中国不同地区的13个猪粪原料沼气工程系统的沼液,利用16S rrnA基因扩增子高通量测序技术研究了原核微生物群落组成及多样性。结果表明,fIrMICuTES是猪粪原料沼气工程系统中的主导微生物,其次为bACTErOIdETES、PrOTEObACTErIA和CHlOrOflEXI。在相似的温度条件下,铵态氮与磷酸盐的比例是影响猪粪原料沼气工程系统原核微生物群落结构及多样性的主要因素。较高的铵磷比会富集fIrMICuTES门的菌群,尤其是ClOSTrIdIuM SEnSu STrICTO属;而较低的铵磷比则有利于bACTErOIdETES和PrOTEObACTErIA。不同营养类型产甲烷菌对高浓度铵态氮耐受程度不同(氢营养型产甲烷菌>METHAnOSArCInA>METHAnOSAETA),影响着产甲烷菌群落组成。产甲烷菌和互营菌的群落组成是影响沼气发酵产气效率的重要生物因素,高比例的氢型产甲烷菌和丙酸互营菌更有利于提高产甲烷效率。Slurry samples from 13 industrial biogas plants using swine manure as raw substrate were collected from different regions in China.The prokaryotic community compositions were investigated using 16S rRNA amplicon high-throughput sequencing technique.The results showed that Firmicutes was the most abundant phylum in these biogas plants, followed by Bacteroidetes, Proteobacteria and Chloroflexi.The ratio of ammonium to phosphate was the main factor affecting prokaryotic community structure and diversity for similar temperatures and substrates.A high ratio of ammonium to phosphate enriched Firmicutes, especially the genus Clostridium sensu stricto, while Bacteroidetes and Proteobacteria preferred a low ratio.Ammonium influenced the compositions of methanogens since their tolerance degrees to ammonium were different(hydrogenotrophic methanoges > Methanosarcina > Methanosaeta).Community compositions of methanogens and syntrophs were the most important biotic factors affecting biogas production rate.Biogas production rate could be increased by increasing the abundances of hydrogenotrophic methanoges and syntrophic propionate-oxidizing bacteria.国家重点基础研究发展计划项目(2013CB733502); 国家自然科学基金项目(41301271;41271260)~

正渗透复合膜的制备及表征

通过在聚砜铸膜液中加入混合添加剂氯化锂和聚乙烯吡咯烷酮(PVP),用相转移法制备出多孔支撑层,然后通过界面聚合制备聚酰胺正渗透复合膜,重点研究了添加剂和聚砜浓度对膜结构和性能的影响。结果表明,氯化锂使得膜支撑层指状孔更加均一,提高孔隙率,并降低海绵层的厚度,提高了水通量;PVP增强了膜的亲水性,并易于成膜,在保持截盐率的同时提高了水通量;随着聚砜浓度增大,支撑层孔隙率变小,海绵状孔层变厚,生成的聚酰胺层更加致密,加重过程内浓差极化,水通量降低。采用质量分数为9%聚砜同时添加氯化锂和PVP的膜支撑层结构均一,孔隙率较大(68.0%),表面亲水性较强(接触角48.5°),优于2种商用三醋酸纤维素正渗透膜的孔隙率(32.6%和25.4%)和接触角(76.5°和73.5°);在正渗透过程中的自制膜水通量为21.9 L/(m2·h),均高于2种商用三醋酸纤维素正渗透膜(9.5和14.4 L/(m2·h))和文献报道的正渗透复合膜通量水平,并维持了一定的截盐率(盐通量为19.9 g/(m2·h)),表现出优异的正渗透性能

正渗透复合膜的制备及表征

通过在聚砜铸膜液中加入混合添加剂氯化锂和聚乙烯吡咯烷酮(PVP),用相转移法制备出多孔支撑层,然后通过界面聚合制备聚酰胺正渗透复合膜,重点研究了添加剂和聚砜浓度对膜结构和性能的影响。结果表明,氯化锂使得膜支撑层指状孔更加均一,提高孔隙率,并降低海绵层的厚度,提高了水通量;PVP增强了膜的亲水性,并易于成膜,在保持截盐率的同时提高了水通量;随着聚砜浓度增大,支撑层孔隙率变小,海绵状孔层变厚,生成的聚酰胺层更加致密,加重过程内浓差极化,水通量降低。采用质量分数为9%聚砜同时添加氯化锂和PVP的膜支撑层结构均一,孔隙率较大(68.0%),表面亲水性较强(接触角48.5°),优于2种商用三醋酸纤维素正渗透膜的孔隙率(32.6%和25.4%)和接触角(76.5°和73.5°);在正渗透过程中的自制膜水通量为21.9 L/(m2·h),均高于2种商用三醋酸纤维素正渗透膜(9.5和14.4 L/(m2·h))和文献报道的正渗透复合膜通量水平,并维持了一定的截盐率(盐通量为19.9 g/(m2·h)),表现出优异的正渗透性能

正渗透复合膜的制备及表征

通过在聚砜铸膜液中加入混合添加剂氯化锂和聚乙烯吡咯烷酮(PVP),用相转移法制备出多孔支撑层,然后通过界面聚合制备聚酰胺正渗透复合膜,重点研究了添加剂和聚砜浓度对膜结构和性能的影响。结果表明,氯化锂使得膜支撑层指状孔更加均一,提高孔隙率,并降低海绵层的厚度,提高了水通量;PVP增强了膜的亲水性,并易于成膜,在保持截盐率的同时提高了水通量;随着聚砜浓度增大,支撑层孔隙率变小,海绵状孔层变厚,生成的聚酰胺层更加致密,加重过程内浓差极化,水通量降低。采用质量分数为9%聚砜同时添加氯化锂和PVP的膜支撑层结构均一,孔隙率较大(68.0%),表面亲水性较强(接触角48.5°),优于2种商用三醋酸纤维素正渗透膜的孔隙率(32.6%和25.4%)和接触角(76.5°和73.5°);在正渗透过程中的自制膜水通量为21.9 L/(m2·h),均高于2种商用三醋酸纤维素正渗透膜(9.5和14.4 L/(m2·h))和文献报道的正渗透复合膜通量水平,并维持了一定的截盐率(盐通量为19.9 g/(m2·h)),表现出优异的正渗透性能

Peer selection algorithm for P2P streaming media in heterogeneous environment

针对异构环境的复杂性和不稳定性,提出一种异构环境下的点对点(P2P)流媒体节点选择算法。利用模糊认知图理论研究异构环境下影响节点性能的多方面因素 之间的关系,计算节点的综合服务能力,并选择服务能力强的节点作为邻居节点;为保证邻居节点具有较强的实时服务能力,利用马尔科夫蒙特卡洛方法进行随机行 走,周期性地更新邻居节点列表,采用Metropolis-Hastings算法计算转移矩阵以满足随机行走的期望静止概率分布。研究结果表明:该算法能 在选择优质邻居节点,提高视频服务质量的同时,保证节点的负载均衡,降低系统消耗,显著提高了系统性能。In view of the complexity and the instability of heterogeneous environment, a peer selection algorithm for P2P streaming media system was proposed. The relationship between the factors which affect the performance of joints under heterogeneous environment was studied, the comprehensive service ability of peers was calculated through the fuzzy cognitive maps theory, and the peers with high service ability were selected as the neighbors. In order to guarantee that the neighbors have a high real time ability, the random walk process was utilized to update the list of neighbors periodically by using Monte Carlo methods. In addition, transition probability matrix was calculated by the Metropolis- Hastings methods to satisfy the expected stationary distribution of random walk. The results show that the proposed algorithm can select excellent peers and ensure the load balance of peers, as well as reduce the consumption of the system and improve the quality of video service and significantly improve system performance