In this paper, a new class of skew multimodal distributions with more flexible than alpha skew normal distribution and alpha-beta skew normal distribution is proposed, which makes some important distributions become i...In this paper, a new class of skew multimodal distributions with more flexible than alpha skew normal distribution and alpha-beta skew normal distribution is proposed, which makes some important distributions become its special cases. The statistical properties of the new distribution are studied in detail, its moment generating function, skewness coefficient, kurtosis coefficient, Fisher information matrix, maximum likelihood estimators are derived. Moreover, a random simulation study is carried out for test the performance of the estimators, the simulation results show that with the increase of sample size, the mean value of maximum likelihood estimators tends to the true value. The new distribution family provides a better fit compared with other known skew distributions through the analysis of a real data set.展开更多
Liquid scintillation counting (LSC) is an adequate nuclear technique to determine radioactivity levels, as verified by this study for the determination of the gross alpha and beta activities of aqueous samples because...Liquid scintillation counting (LSC) is an adequate nuclear technique to determine radioactivity levels, as verified by this study for the determination of the gross alpha and beta activities of aqueous samples because of its simplicity and low associated cost comparison with other techniques. This paper discusses a new approach to the monitoring of gross alpha and gross beta activities in water. The method consists of using pulse decay discrimination (PDD) liquid scintillation counting LSC of 2 ml of the sample after conditioning with 12 ml of AB-Ultima Gold LSC cocktail, and PDD 139 condition. Different factors that affected on the counting efficiency were studied such as quench reaction, volume of sample, and type of vial. The gross alpha and gross beta particle activity measurement using 40K and 243Am with different activities concentration for efficiency determination. The calculated detection limits were 0.07 Bq/l and 0.12 Bq/l for gross alpha and gross beta respectively for 500 min measurements of samples produced by concentration of one liter of water.展开更多
针对石化废水处理系统中硫化物浓度梯度变化,对微生物群落结构的驱动作用展开分析.通过采集辽宁某石化企业厌氧-移动床生物膜反应器(moving bed biofilm reactor,MBBR)-好氧(A-MBBR-O)复合工艺中厌氧池(A)、MBBR池(M)和好氧池(O)的污泥...针对石化废水处理系统中硫化物浓度梯度变化,对微生物群落结构的驱动作用展开分析.通过采集辽宁某石化企业厌氧-移动床生物膜反应器(moving bed biofilm reactor,MBBR)-好氧(A-MBBR-O)复合工艺中厌氧池(A)、MBBR池(M)和好氧池(O)的污泥样本,利用Illumina高通量测序技术解析微生物群落的响应特征.结果表明:Proteobacteria为优势菌门,与Chloroflexi、Bacteroidota共同维持系统运行稳定性;随着硫化物浓度升高,烃降解相关菌属Acinetobacter的相对丰度受到抑制,而Desulfobacterota等硫酸盐还原菌呈现富集趋势.Alpha多样性分析表明,在高浓度硫化物胁迫条件下,MBBR池中微生物群落的物种丰富度与均匀度相对稳定,而好氧池多样性明显降低.RDA分析结果显示,硫化物是影响微生物群落结构变化的重要环境因子,与Desulfobacterota呈正相关关系,与Crenarchaeota等呈负相关关系.LEfSe分析识别出具有浓度依赖特征的优势菌群:在低浓度硫化物冲击条件下,Desulfovibrio相对丰度较高;在高浓度硫化物冲击条件下,Thiobacillus成为潜在的重要功能菌属.本研究为石化废水处理中不同硫化物胁迫条件下的微生物调控提供了理论参考.展开更多
Staphylococcus aureus(S.aureus)are frequently encountered for both nosocomial infections and community acquired infections,with special concerns on the quick emergence of methicillin resistant S.aureus(MRSA)[1,2].Anti...Staphylococcus aureus(S.aureus)are frequently encountered for both nosocomial infections and community acquired infections,with special concerns on the quick emergence of methicillin resistant S.aureus(MRSA)[1,2].Antibiotics are used extensively to treat these infections[2].However,antimicrobial resistance has been a tremendous challenge against current antibiotic and calls for urgent actions to explore novel antimicrobial agents that are active against MRSA and are less susceptible to antimicrobial resistance than do conventional antibiotics[3–13].Encouraged by the low propensity for microbes to develop antimicrobial resistance,host defense peptides(HDPs)and their synthetic mimics were actively studied[3,4,14–34].Although peptidyl mimics of HDP have variable structures,many of them involved multiple copies ofα-L-lysine to introduce into the molecules positive charges that were critical for the antimicrobial activity[35,36].展开更多
文摘In this paper, a new class of skew multimodal distributions with more flexible than alpha skew normal distribution and alpha-beta skew normal distribution is proposed, which makes some important distributions become its special cases. The statistical properties of the new distribution are studied in detail, its moment generating function, skewness coefficient, kurtosis coefficient, Fisher information matrix, maximum likelihood estimators are derived. Moreover, a random simulation study is carried out for test the performance of the estimators, the simulation results show that with the increase of sample size, the mean value of maximum likelihood estimators tends to the true value. The new distribution family provides a better fit compared with other known skew distributions through the analysis of a real data set.
文摘Liquid scintillation counting (LSC) is an adequate nuclear technique to determine radioactivity levels, as verified by this study for the determination of the gross alpha and beta activities of aqueous samples because of its simplicity and low associated cost comparison with other techniques. This paper discusses a new approach to the monitoring of gross alpha and gross beta activities in water. The method consists of using pulse decay discrimination (PDD) liquid scintillation counting LSC of 2 ml of the sample after conditioning with 12 ml of AB-Ultima Gold LSC cocktail, and PDD 139 condition. Different factors that affected on the counting efficiency were studied such as quench reaction, volume of sample, and type of vial. The gross alpha and gross beta particle activity measurement using 40K and 243Am with different activities concentration for efficiency determination. The calculated detection limits were 0.07 Bq/l and 0.12 Bq/l for gross alpha and gross beta respectively for 500 min measurements of samples produced by concentration of one liter of water.
文摘针对石化废水处理系统中硫化物浓度梯度变化,对微生物群落结构的驱动作用展开分析.通过采集辽宁某石化企业厌氧-移动床生物膜反应器(moving bed biofilm reactor,MBBR)-好氧(A-MBBR-O)复合工艺中厌氧池(A)、MBBR池(M)和好氧池(O)的污泥样本,利用Illumina高通量测序技术解析微生物群落的响应特征.结果表明:Proteobacteria为优势菌门,与Chloroflexi、Bacteroidota共同维持系统运行稳定性;随着硫化物浓度升高,烃降解相关菌属Acinetobacter的相对丰度受到抑制,而Desulfobacterota等硫酸盐还原菌呈现富集趋势.Alpha多样性分析表明,在高浓度硫化物胁迫条件下,MBBR池中微生物群落的物种丰富度与均匀度相对稳定,而好氧池多样性明显降低.RDA分析结果显示,硫化物是影响微生物群落结构变化的重要环境因子,与Desulfobacterota呈正相关关系,与Crenarchaeota等呈负相关关系.LEfSe分析识别出具有浓度依赖特征的优势菌群:在低浓度硫化物冲击条件下,Desulfovibrio相对丰度较高;在高浓度硫化物冲击条件下,Thiobacillus成为潜在的重要功能菌属.本研究为石化废水处理中不同硫化物胁迫条件下的微生物调控提供了理论参考.
基金supported by the National Natural Science Foundation of China (21574038 and 21774031)the National Natural Science Foundation of China for Innovative Research Groups (51621002)+6 种基金the National Key Research and Development Program of China (2016YFC1100401)the Natural Science Foundation of Shanghai (18ZR1410300)the "Eastern Scholar Professorship" from Shanghai local government (TP2014034)the national special fund for State Key Laboratory of Bioreactor Engineering (2060204)the 1000 Talent Young Scholar program in China111 project (B14018)the program for professor of special appointment at ECUST
文摘Staphylococcus aureus(S.aureus)are frequently encountered for both nosocomial infections and community acquired infections,with special concerns on the quick emergence of methicillin resistant S.aureus(MRSA)[1,2].Antibiotics are used extensively to treat these infections[2].However,antimicrobial resistance has been a tremendous challenge against current antibiotic and calls for urgent actions to explore novel antimicrobial agents that are active against MRSA and are less susceptible to antimicrobial resistance than do conventional antibiotics[3–13].Encouraged by the low propensity for microbes to develop antimicrobial resistance,host defense peptides(HDPs)and their synthetic mimics were actively studied[3,4,14–34].Although peptidyl mimics of HDP have variable structures,many of them involved multiple copies ofα-L-lysine to introduce into the molecules positive charges that were critical for the antimicrobial activity[35,36].
