针对加工番茄不同品种间的品质特性差异,本文提出基于Simultaneous Evaluation of Criteria and Alternatives(SECA)方法的加工番茄种质资源综合评价方法.基于该方法对50种加工番茄6个品质特性的内部及之间的差异进行分析,得出6种品质...针对加工番茄不同品种间的品质特性差异,本文提出基于Simultaneous Evaluation of Criteria and Alternatives(SECA)方法的加工番茄种质资源综合评价方法.基于该方法对50种加工番茄6个品质特性的内部及之间的差异进行分析,得出6种品质特性霉菌比、青果比、颜色值、加工局限性、固形物含量比和pH值的各项权值,同时对所有品种进行综合评价.依据结果将加工番茄品种划分为特级、一级和二级,可选取特级中综合评价最高的5个品种作为新品种引入,为培育更适合本地种植的加工番茄品种提供决策支持和参考依据.该方法避免了传统方法中权重确定的主观性,对加工番茄的多个品质特性进行全面客观的评价,无需人为设定理想品质参数,适用性更高,排序结果直观且可信度高.展开更多
SecA,the ATPase of Sec translocase,mediates the post-translational translocation of preprotein through the protein-conduct-ing channel SecYEG in the bacterial inner membrane.Here we report the structures of Escherichi...SecA,the ATPase of Sec translocase,mediates the post-translational translocation of preprotein through the protein-conduct-ing channel SecYEG in the bacterial inner membrane.Here we report the structures of Escherichia coli Sec intermediates during preprotein translocation as visualized by electron microscopy to probe the oligomeric states of SecA during this process.We found that the translocase holoenzyme is symmetrically assembled by SecA and SecYEG on proteoliposomes,whereas the translocation intermediate 31 (I31) becomes asymmetric because of the presence of preprotein.Moreover,SecA is a dimer in these two translocation complexes.This work also shows surface topological changes in the components of translocation intermediates by immunogold labeling.The channel entry for preprotein translocation was found at the center of the I31 structures.Our results indicate that the presence of preprotein introduces asymmetry into translocation intermediates,while SecA remains dimeric during the translocation process.展开更多
SecA is the essential component of the signal-peptide dependent translocation pathway in Escherichia coil （E.coh）. The structure and function of SecA must be known to understand the molecular mechanism of preprotein...SecA is the essential component of the signal-peptide dependent translocation pathway in Escherichia coil （E.coh）. The structure and function of SecA must be known to understand the molecular mechanism of preprotein translocation. The high flexibility of SecA causes a dynamic conformational heterogeneity which presents a barrier to the growth of crystals of high diffraction quality. Electron microscopy was used to resolve the macromolecular structure of SecA in solution by negative staining and single particle analysis at a resolution of 2.9 nm. The structure of E. coil SecA is similar to the dimeric form of Bacillus subtilis SecA and is 10 nm × 10 nm × 5 nm in size.展开更多
Health problems caused by bacterial infection have become a major public health concern in recent years due to the widespread emergence of drug-resistant bacterial strains.Therefore,the need for the development of new...Health problems caused by bacterial infection have become a major public health concern in recent years due to the widespread emergence of drug-resistant bacterial strains.Therefore,the need for the development of new types of antimicrobial agents,especially those with a novel mechanism of action,is urgent.SecA,one of the key components of the secretion(Sec) pathway,is a new promising target for antimicrobial agent design.In recent years,promising leads targeting SecA have been identified and the feasibility of developing antimicrobial agents through the inhibition of SecA has been demonstrated.We hope this review will help stimulate more research in this area so that new antimicrobials can be obtained by targeting SecA.展开更多
在硫排放控制区(Sulphur Emission Control Area,SECA)及碳税背景下,为获得水路运输中船舶的最佳航速,满足排放要求同时实现航次成本最小化,以亚欧航线的集装箱船舶功率、容量等真实航行数据为基础,建立了混合整数凸成本最小化模型。该...在硫排放控制区(Sulphur Emission Control Area,SECA)及碳税背景下,为获得水路运输中船舶的最佳航速,满足排放要求同时实现航次成本最小化,以亚欧航线的集装箱船舶功率、容量等真实航行数据为基础,建立了混合整数凸成本最小化模型。该模型以单一航线的船速为决策变量,综合考虑航速与航行时间、船舶数量、燃油消耗、航次成本之间的非线性关系,并给出具体算例的数值结果以及航程内SECA所占航距和时间惩罚变化的灵敏度分析,进一步验证了模型的有效性。试验结果表明,SECA的设立可以减少全球范围内的硫排放量,但在控制碳排放量方面收效甚微。在一定时间约束下,船舶采用在SECA内适当减速,SECA外增加航速的航行策略能够有效平衡航次成本和排放量。展开更多
The fuel sulfur content in marine fuels has been regulated in Sulfur Emission Control Areas(SECAs) since January 2015. However, other fuel characteristics are also believed to have an impact on particle emissions, par...The fuel sulfur content in marine fuels has been regulated in Sulfur Emission Control Areas(SECAs) since January 2015. However, other fuel characteristics are also believed to have an impact on particle emissions, particularly on the number of particles emitted. This study investigates the impact of the content of aromatics in fuel. To achieve fuel blends with concentrations of aromatics similar to those found in marine fuel oils, i.e. 20%–30% by volume(%vol.), normal diesel oil(4%–5% vol. aromatics) is doped with a mixture of aromatics. Emission measurements are conducted in test-bed engine facilities and particle emissions over a wide size range are analyzed. Results show a decreased number of particles emitted(or not change) with an increase in the aromatic concentration in fuel. This is because there is a reduction in the cetane number of the fuel with an increased aromatic content, which effects the combustion process and results in decreased particle formation. However, when ignition improver is used to increase the cetane number, particle emissions remain at a lower level than for normal diesel oil; thereby emphasizing the presence of other factors in the formation of particles.展开更多
文摘针对加工番茄不同品种间的品质特性差异,本文提出基于Simultaneous Evaluation of Criteria and Alternatives(SECA)方法的加工番茄种质资源综合评价方法.基于该方法对50种加工番茄6个品质特性的内部及之间的差异进行分析,得出6种品质特性霉菌比、青果比、颜色值、加工局限性、固形物含量比和pH值的各项权值,同时对所有品种进行综合评价.依据结果将加工番茄品种划分为特级、一级和二级,可选取特级中综合评价最高的5个品种作为新品种引入,为培育更适合本地种植的加工番茄品种提供决策支持和参考依据.该方法避免了传统方法中权重确定的主观性,对加工番茄的多个品质特性进行全面客观的评价,无需人为设定理想品质参数,适用性更高,排序结果直观且可信度高.
基金supported by the National Natural Science Foundation of China (Grant No. 30830028)the National Basic Research program of China (Grant No. 2010CD833706/2010CB912400) (S.F.S.)the National Institutes of Health (Grant No. GM34766 to PCT)
文摘SecA,the ATPase of Sec translocase,mediates the post-translational translocation of preprotein through the protein-conduct-ing channel SecYEG in the bacterial inner membrane.Here we report the structures of Escherichia coli Sec intermediates during preprotein translocation as visualized by electron microscopy to probe the oligomeric states of SecA during this process.We found that the translocase holoenzyme is symmetrically assembled by SecA and SecYEG on proteoliposomes,whereas the translocation intermediate 31 (I31) becomes asymmetric because of the presence of preprotein.Moreover,SecA is a dimer in these two translocation complexes.This work also shows surface topological changes in the components of translocation intermediates by immunogold labeling.The channel entry for preprotein translocation was found at the center of the I31 structures.Our results indicate that the presence of preprotein introduces asymmetry into translocation intermediates,while SecA remains dimeric during the translocation process.
基金Supported by the National Natural Science Foundation of China (Nos. 30170196 and 30330160)
文摘SecA is the essential component of the signal-peptide dependent translocation pathway in Escherichia coil （E.coh）. The structure and function of SecA must be known to understand the molecular mechanism of preprotein translocation. The high flexibility of SecA causes a dynamic conformational heterogeneity which presents a barrier to the growth of crystals of high diffraction quality. Electron microscopy was used to resolve the macromolecular structure of SecA in solution by negative staining and single particle analysis at a resolution of 2.9 nm. The structure of E. coil SecA is similar to the dimeric form of Bacillus subtilis SecA and is 10 nm × 10 nm × 5 nm in size.
文摘Health problems caused by bacterial infection have become a major public health concern in recent years due to the widespread emergence of drug-resistant bacterial strains.Therefore,the need for the development of new types of antimicrobial agents,especially those with a novel mechanism of action,is urgent.SecA,one of the key components of the secretion(Sec) pathway,is a new promising target for antimicrobial agent design.In recent years,promising leads targeting SecA have been identified and the feasibility of developing antimicrobial agents through the inhibition of SecA has been demonstrated.We hope this review will help stimulate more research in this area so that new antimicrobials can be obtained by targeting SecA.
文摘在硫排放控制区(Sulphur Emission Control Area,SECA)及碳税背景下,为获得水路运输中船舶的最佳航速,满足排放要求同时实现航次成本最小化,以亚欧航线的集装箱船舶功率、容量等真实航行数据为基础,建立了混合整数凸成本最小化模型。该模型以单一航线的船速为决策变量,综合考虑航速与航行时间、船舶数量、燃油消耗、航次成本之间的非线性关系,并给出具体算例的数值结果以及航程内SECA所占航距和时间惩罚变化的灵敏度分析,进一步验证了模型的有效性。试验结果表明,SECA的设立可以减少全球范围内的硫排放量,但在控制碳排放量方面收效甚微。在一定时间约束下,船舶采用在SECA内适当减速,SECA外增加航速的航行策略能够有效平衡航次成本和排放量。
基金Angpanneföreningen’s Foundation for Research and Development(11-164)the Foundation for Swedish Environmental Research Institute(SIVL)Swedish Maritime Organization and Lighthouse for their financial support
文摘The fuel sulfur content in marine fuels has been regulated in Sulfur Emission Control Areas(SECAs) since January 2015. However, other fuel characteristics are also believed to have an impact on particle emissions, particularly on the number of particles emitted. This study investigates the impact of the content of aromatics in fuel. To achieve fuel blends with concentrations of aromatics similar to those found in marine fuel oils, i.e. 20%–30% by volume(%vol.), normal diesel oil(4%–5% vol. aromatics) is doped with a mixture of aromatics. Emission measurements are conducted in test-bed engine facilities and particle emissions over a wide size range are analyzed. Results show a decreased number of particles emitted(or not change) with an increase in the aromatic concentration in fuel. This is because there is a reduction in the cetane number of the fuel with an increased aromatic content, which effects the combustion process and results in decreased particle formation. However, when ignition improver is used to increase the cetane number, particle emissions remain at a lower level than for normal diesel oil; thereby emphasizing the presence of other factors in the formation of particles.
