The sediment redox potential was raised in the laboratory to estimate reduction of internal available phosphorus loads,such as soluble reactive phosphorus(SRP)and total phosphorus(TP),as well as the main elements of s...The sediment redox potential was raised in the laboratory to estimate reduction of internal available phosphorus loads,such as soluble reactive phosphorus(SRP)and total phosphorus(TP),as well as the main elements of sediment extracts in Dianchi Lake.Several strongly reducing substances in sediments,which mainly originated from anaerobic decomposition of primary producer residues,were responsible for the lower redox potential.In a range of -400 to 200 mV raising the redox potential of sediments decreased TP and SRP in interstitial water.Redox potentials exceeding 320 mV caused increases in TP,whereas SRP maintained a relatively constant minimum level.The concentrations of Al,Fe, Ca^(2+),Mg^(2+),K^+,Na^+ and S in interstitial water were also related to the redox potential of sediments,suggesting that the mechanism for redox potential to regulate the concentration of phosphorus in interstitial water was complex.展开更多
The bioavailability of phosphorus in lake sediment mainly depends on its forms. Therefore, reactive phosphorus (RP) pool of the sediment in a shallow eutrophic lake(Donghu Lake) was determined seasonally and spatia...The bioavailability of phosphorus in lake sediment mainly depends on its forms. Therefore, reactive phosphorus (RP) pool of the sediment in a shallow eutrophic lake(Donghu Lake) was determined seasonally and spatially by sequential chemical extraction according to the scheme proposed by Psenner et al. (Psenner, 1985) and its modified version respectively. The ammonium chloride extracted 3%—7% of the total reactive phosphorus (Tot-RP), while the distilled water extracted less(<3%). These two forms of P were significantly higher at the most eutrophic stations(I and IV). The sum of BD-RP(reductant soluble P) and NaOH-RP extracted accounted for 57%—81% of Tot-RP, which could play significant roles in P cycling. The percentages of HCl-extractable RP in the sediments of station III, however, were usually much more than those of other stations, which could reflect the original geochemistrical characteristics and trophic status of the sediments. It was noted that the sediment RP in different fractions varied in different months studied.展开更多
Lead zirconate titanate piezoelectric ceramics have important applications in space and aerospace technology,but the effect and physical mechanism of charged particle radiation on their performance yet to be clarified...Lead zirconate titanate piezoelectric ceramics have important applications in space and aerospace technology,but the effect and physical mechanism of charged particle radiation on their performance yet to be clarified.In this study,we characterized PbZr_(0.52)Ti_(0.48)O_(3)(PZT)thin films,and changes in the ferroelectric properties of the films before and after electron and proton irradiation were investigated.The natural and heat treatment recoverability of the ferroelectric properties were studied,and the damages and mechanisms of different types of radiation in PZT films were also investigated.The results show that,in addition to ionization damages,electron irradiation causes certain structural damage on the PZT film,and the large structural damage caused by proton irradiation reduces drastically the ferroelectricity of the PZT film.展开更多
通过探讨参苓白术散加减治疗溃疡性结肠炎(UC)的有效性和安全性,为临床推广提供科学依据。计算机检索CNKI,CBM,万方,维普等数据库,纳入参苓白术散加减对比单用西药治疗溃疡性结肠炎的随机对照试验文献(randomized control trials,RCTs),...通过探讨参苓白术散加减治疗溃疡性结肠炎(UC)的有效性和安全性,为临床推广提供科学依据。计算机检索CNKI,CBM,万方,维普等数据库,纳入参苓白术散加减对比单用西药治疗溃疡性结肠炎的随机对照试验文献(randomized control trials,RCTs),用Cochrane评价方法进行风险偏倚评估;收集纳入研究的有效率、主要症状(腹泻、腹痛、便脓血、发热)的改善时间和肠镜下黏膜疗效,并进行Meta分析。本研究共纳入13篇RCTs,总例数1 285例,参苓白术散组659例,单用西药组598例。对比单用西药,参苓白术散加减有较高临床疗效(RR=1.17,95%CI[1.13,1.22],P<0.001),能明显缩短腹泻、腹痛、便脓血、发热症状的改善时间,其合并效应量分别为(RR=-12.32,95%CI[-14.27,-10.37],P<0.001),(RR=-8.06,95%CI[-9.88,-6.24],P<0.001),(RR=-9.89,95%CI[-10.77,-9.00],P<0.001),(RR=-8.29,95%CI[-9.59,-6.98],P<0.001),减少不良反应事件的发生(RR=0.06,95%CI[0.01,0.40],P=0.004)。参苓白术散加减治疗UC的肠镜下黏膜疗效比较没有统计学意义。对比单用西药,参苓白术散加减治疗溃疡性结肠炎有更好的疗效和安全性,适合临床推广使用,但由于纳入文献数目较少,质量较低,需要高质量的大样本双盲随机对照试验的支持。展开更多
基金Project supported by the National Natural Science Foundation of China(No.40401029).
文摘The sediment redox potential was raised in the laboratory to estimate reduction of internal available phosphorus loads,such as soluble reactive phosphorus(SRP)and total phosphorus(TP),as well as the main elements of sediment extracts in Dianchi Lake.Several strongly reducing substances in sediments,which mainly originated from anaerobic decomposition of primary producer residues,were responsible for the lower redox potential.In a range of -400 to 200 mV raising the redox potential of sediments decreased TP and SRP in interstitial water.Redox potentials exceeding 320 mV caused increases in TP,whereas SRP maintained a relatively constant minimum level.The concentrations of Al,Fe, Ca^(2+),Mg^(2+),K^+,Na^+ and S in interstitial water were also related to the redox potential of sediments,suggesting that the mechanism for redox potential to regulate the concentration of phosphorus in interstitial water was complex.
文摘The bioavailability of phosphorus in lake sediment mainly depends on its forms. Therefore, reactive phosphorus (RP) pool of the sediment in a shallow eutrophic lake(Donghu Lake) was determined seasonally and spatially by sequential chemical extraction according to the scheme proposed by Psenner et al. (Psenner, 1985) and its modified version respectively. The ammonium chloride extracted 3%—7% of the total reactive phosphorus (Tot-RP), while the distilled water extracted less(<3%). These two forms of P were significantly higher at the most eutrophic stations(I and IV). The sum of BD-RP(reductant soluble P) and NaOH-RP extracted accounted for 57%—81% of Tot-RP, which could play significant roles in P cycling. The percentages of HCl-extractable RP in the sediments of station III, however, were usually much more than those of other stations, which could reflect the original geochemistrical characteristics and trophic status of the sediments. It was noted that the sediment RP in different fractions varied in different months studied.
基金supported by the National Natural Science Foundation of China(Grant No.51802056)the Science Foundation of the National Key Laboratory of Science and Technology on Advanced Composites in Special Environmentsthe Key Laboratory of Micro-systems and Micro-structures Manufacturing(Harbin Institute of Technology),Ministry of Education,China。
文摘Lead zirconate titanate piezoelectric ceramics have important applications in space and aerospace technology,but the effect and physical mechanism of charged particle radiation on their performance yet to be clarified.In this study,we characterized PbZr_(0.52)Ti_(0.48)O_(3)(PZT)thin films,and changes in the ferroelectric properties of the films before and after electron and proton irradiation were investigated.The natural and heat treatment recoverability of the ferroelectric properties were studied,and the damages and mechanisms of different types of radiation in PZT films were also investigated.The results show that,in addition to ionization damages,electron irradiation causes certain structural damage on the PZT film,and the large structural damage caused by proton irradiation reduces drastically the ferroelectricity of the PZT film.
文摘通过探讨参苓白术散加减治疗溃疡性结肠炎(UC)的有效性和安全性,为临床推广提供科学依据。计算机检索CNKI,CBM,万方,维普等数据库,纳入参苓白术散加减对比单用西药治疗溃疡性结肠炎的随机对照试验文献(randomized control trials,RCTs),用Cochrane评价方法进行风险偏倚评估;收集纳入研究的有效率、主要症状(腹泻、腹痛、便脓血、发热)的改善时间和肠镜下黏膜疗效,并进行Meta分析。本研究共纳入13篇RCTs,总例数1 285例,参苓白术散组659例,单用西药组598例。对比单用西药,参苓白术散加减有较高临床疗效(RR=1.17,95%CI[1.13,1.22],P<0.001),能明显缩短腹泻、腹痛、便脓血、发热症状的改善时间,其合并效应量分别为(RR=-12.32,95%CI[-14.27,-10.37],P<0.001),(RR=-8.06,95%CI[-9.88,-6.24],P<0.001),(RR=-9.89,95%CI[-10.77,-9.00],P<0.001),(RR=-8.29,95%CI[-9.59,-6.98],P<0.001),减少不良反应事件的发生(RR=0.06,95%CI[0.01,0.40],P=0.004)。参苓白术散加减治疗UC的肠镜下黏膜疗效比较没有统计学意义。对比单用西药,参苓白术散加减治疗溃疡性结肠炎有更好的疗效和安全性,适合临床推广使用,但由于纳入文献数目较少,质量较低,需要高质量的大样本双盲随机对照试验的支持。
