Effects of column temperature and flow rate on separation of organic acids were studied by determining nine low-molecular-weight organic acids on reversed- phase C18 column, using high performance liquid chromatograph...Effects of column temperature and flow rate on separation of organic acids were studied by determining nine low-molecular-weight organic acids on reversed- phase C18 column, using high performance liquid chromatography (HPLC) with a wavelength of UV (ultraviolet) 214 urn and a mobile phase of 18 mmol L-1 KH2PO4 buffer solution (pH 2.1). The thermal stability of organic acids was determined by comparing the recoveries of organic acids in different temperature treatments. The relationships between column temperature, flow rate or solvent pH and retention time were analyzed. At low solvent pH, separation efficiency of organic acids was increased by raising the flow rate of the solvent because of lowering the retention time of organic acids. High column temperature was unfavorable for the separation of organic acids. The separating effect can be enhanced through reducing column temperature in organic acid determination due to increasing retention time. High thermal stability of organic acids with low concentrations was observed at temperature of 40 ℃-45℃. Sensitivity and separation effect of organic acid determination by HPLC were clearly improved by a combination of raising flow rate and lowering column temperature at low solvent pH.展开更多
The phosphorus uptake (PU) in above-ground parts of plant,root characteristics and root exudations as well as the quantitative trait loci (QTLs) associated with these characteristics were determined for a F2:3 populat...The phosphorus uptake (PU) in above-ground parts of plant,root characteristics and root exudations as well as the quantitative trait loci (QTLs) associated with these characteristics were determined for a F2:3 population derived from the cross of two contrasting maize (Zea mays L.) genotypes,082 and Ye107.A total of 241 F2:3 families were evaluated in replicated trials under deficient phosphorus conditions in 2007 at two sites (Kaixian County and Southwest University,Chongqing,P.R.China).The results show pleiotropy and close linkage among QTLs.Four common regions in different environments were in bnlg100bnlg1268b (bins 1.02) for QTL of H+,bnlg1268a-umc1290a (bins 1.09) for QTL of AP (acid phosphatase activity),dupssr15-P1M7/a (bins 6.06) for QTLs of PU (phosphorus uptake) and RW (root weight),and P1M3/d-P1M3/g (bins9.04) for QTLs of PU and AP.These QTLs are non-environment or minor QTLs × environment.By epistatic analysis,three main QTLs and eighteen QTLs × QTLs interactions were detected for the seven measured characteristics.These QTLs may affect trait expression by epistatic interaction with the other loci,and make a substantial contribution to phosphorus utilization efficiency,which should be considered when breeding maize varieties with high P efficiency.Two regions were detected in dupssr15-P1M7/a (bins 6.06) for QTL of RW and P1M3/d-P1M3/g (bins 9.04) for QTL of PU and AP.They were detected in two different environments and by two methods of QTL analysis,which were useful for marker-assisted selection.展开更多
文摘目的：采用系统评价方法探讨根尖周炎时根尖渗出液中前列腺素E2（prostaglandin E2,PGE2）在常规根管治疗后浓度的变化。方法：计算机检索Pub Med、EMbase、CNKI、CBM、万方、维普等数据库,按照纳入、排除标准选择文献,收集1990年1月至2015年4月国内外报道的有关根尖周炎根管治疗前后根尖渗出液中PGE2浓度的研究文献,采用Rev Man 5.3软件对原始数据系统评价并进行异质性检验和敏感性分析。结果：共有5篇自身前后配对设计研究纳入研究范围,其中治疗前组共178例,治疗后组共163例。系统分析结果显示,根尖渗出液中PGE2的浓度在治疗前和治疗后差异有统计学意义,在经过常规根管治疗后,根尖渗出液中的PGE2浓度显著下降,MD=46.33,95%CI（35.22~57.45）,P〈0.000。亚组分析与敏感性分析结果与上述结果一致。结论：常规根管治疗能降低根尖周炎根尖渗出液中PGE2浓度,减轻根尖周炎症状。
文摘Effects of column temperature and flow rate on separation of organic acids were studied by determining nine low-molecular-weight organic acids on reversed- phase C18 column, using high performance liquid chromatography (HPLC) with a wavelength of UV (ultraviolet) 214 urn and a mobile phase of 18 mmol L-1 KH2PO4 buffer solution (pH 2.1). The thermal stability of organic acids was determined by comparing the recoveries of organic acids in different temperature treatments. The relationships between column temperature, flow rate or solvent pH and retention time were analyzed. At low solvent pH, separation efficiency of organic acids was increased by raising the flow rate of the solvent because of lowering the retention time of organic acids. High column temperature was unfavorable for the separation of organic acids. The separating effect can be enhanced through reducing column temperature in organic acid determination due to increasing retention time. High thermal stability of organic acids with low concentrations was observed at temperature of 40 ℃-45℃. Sensitivity and separation effect of organic acid determination by HPLC were clearly improved by a combination of raising flow rate and lowering column temperature at low solvent pH.
基金Funded by Chongqing Key Scientific and Technological Project (No. CSTC2007AB1045)Chinese Key Scientific and Technological Project (No. 2006BAD13B03)
文摘The phosphorus uptake (PU) in above-ground parts of plant,root characteristics and root exudations as well as the quantitative trait loci (QTLs) associated with these characteristics were determined for a F2:3 population derived from the cross of two contrasting maize (Zea mays L.) genotypes,082 and Ye107.A total of 241 F2:3 families were evaluated in replicated trials under deficient phosphorus conditions in 2007 at two sites (Kaixian County and Southwest University,Chongqing,P.R.China).The results show pleiotropy and close linkage among QTLs.Four common regions in different environments were in bnlg100bnlg1268b (bins 1.02) for QTL of H+,bnlg1268a-umc1290a (bins 1.09) for QTL of AP (acid phosphatase activity),dupssr15-P1M7/a (bins 6.06) for QTLs of PU (phosphorus uptake) and RW (root weight),and P1M3/d-P1M3/g (bins9.04) for QTLs of PU and AP.These QTLs are non-environment or minor QTLs × environment.By epistatic analysis,three main QTLs and eighteen QTLs × QTLs interactions were detected for the seven measured characteristics.These QTLs may affect trait expression by epistatic interaction with the other loci,and make a substantial contribution to phosphorus utilization efficiency,which should be considered when breeding maize varieties with high P efficiency.Two regions were detected in dupssr15-P1M7/a (bins 6.06) for QTL of RW and P1M3/d-P1M3/g (bins 9.04) for QTL of PU and AP.They were detected in two different environments and by two methods of QTL analysis,which were useful for marker-assisted selection.
