The Kop ophiolite in NE Turkey is a fragment of Neo-Tethyan forearc.It can be mainly divided into a paleo-Moho transition zone(MTZ)in the North and a harzburgitic mantle sequence in the South.Dunites are predominant i...The Kop ophiolite in NE Turkey is a fragment of Neo-Tethyan forearc.It can be mainly divided into a paleo-Moho transition zone(MTZ)in the North and a harzburgitic mantle sequence in the South.Dunites are predominant in the MTZ of the Kop ophiolite,and they are locally interlayered with chromitites and enclose minor bodies of harzburgites near the petrological Moho boundary.Large Fe isotopic variations were observed for magnesiochromite(-0.14‰to 0.06‰)and olivine(-0.12‰to 0.14‰)from the MTZ chromitites,dunites and harzburgites.In individual dunite samples,magnesiochromite usually has lighter Fe isotopic compositions than olivine,which was probably caused by subsolidus Mg-Fe exchange between the two mineral phases.Both magnesiochromite and olivine display an increasing trend ofδ56Fe along a profile from chromitite todunite.This trend reflects continuous fractional crystallization in a magma chamber,which resulted in heavier Fe isotopes concentrated in the evolved magmas.In each cumulative cycle of chromitite and dunite,dunite was formed from relatively evolved melts after massive precipitation of magnesiochromite.Mixing of more primitive and evolved melts in the magma chamber was a potential mechanism for triggering the crystallization of magnesiochromite,generating chromitite layers in the cumulate pile.Before mixing happened,the primitive melts had reacted with mantle harzburgites during their ascendance;whereas the evolved melts may lie on the olivine-chromite cotectic near the liquidus field of pyroxene.Variable degrees of magma mixing and differentiation are expected to generate melts with differentδ56Fe values,accounting for the Fe isotopic variations of the Kop MTZ.展开更多
The effects of ammonium (NH4+-N) and nitrate (NO3- - N) were examined on Fe fractions and FeCN (ferricyanide) reductase activity in intact root tips (0-3 cm) of young maize (Zea mays L. cv. Lenz) in solution culture b...The effects of ammonium (NH4+-N) and nitrate (NO3- - N) were examined on Fe fractions and FeCN (ferricyanide) reductase activity in intact root tips (0-3 cm) of young maize (Zea mays L. cv. Lenz) in solution culture by using short-term experiment under controlled Fe deficiency conditions (containing high HCO3- concentration in pre-culture solution). The results showed that Fe(Ⅱ) concentrations in root tip apoplast of maize were only 20-40 nmol/g FW which accounted for 7%-13% of total Fe. Most of Fe in root tips existed as Fe(Ⅲ) compounds. Imposition of the roots to NH4+ - N or NO3- - N for 60 min led to an increase of Fe(Ⅱ) in root tip apoplast. NH4+ - N led to an increased concentration of Fe(Ⅱ) and exchangeable Fe (Fe(Ⅱ) and Fe (Ⅲ)) in root tips, while NO3- - N increased FeCN reductase activity. The relationship between pH and Fe fractions, FeCN reductase activity was also discussed.展开更多
The phosphorus（P） fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid（HA） complexes were analyzed using the ultrafiltration method in this...The phosphorus（P） fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid（HA） complexes were analyzed using the ultrafiltration method in this study.With an initial P concentration of 20 mg/L（I =0.01 mol/L and pH = 7）,it was shown that the colloid（1 kDa-0.45 μm） component of P accounted for 10.6%,11.6%,6.5%,and 4.0%of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite（FH）,goethite（GE）,ferrihydrite-humic acid complex（FH-HA）,goethite-humic acid complex（GE-HA）,respectively.The 〈1 kDa component of P was still the predominant fraction in the supernatant,and underestimated colloidal P accounted for 2.2%,55.1%,45.5%,and 38.7%of P adsorption onto the solid surface of FH,FH-HA,GE and GE-HA,respectively.Thus,the colloid P could not be neglected.Notably,it could be interpreted that Fe3＋ hydrolysis from the adsorbents followed by the formation of colloidal hydrous ferric oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant.And colloidal adsorbent particles co-existing in the supernatant were another important reason for it.Additionally,dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant.Ultimately,we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P,even when considering other contaminants such as organic pollutants,heavy metal ions,and arsenate at the sediment/soil-water interface in the real environment.展开更多
目的探究基于mDixon-Quant的胰腺脂肪分数(Fat faction,FF)、T2^(*)弛豫时间与代谢综合征(Metabolic syndrome,MetS)患者各代谢组分之间的关系,同时分析其对MetS的预测能力。方法本研究前瞻性收集2023年6月至2024年6月于牡丹江医科大学...目的探究基于mDixon-Quant的胰腺脂肪分数(Fat faction,FF)、T2^(*)弛豫时间与代谢综合征(Metabolic syndrome,MetS)患者各代谢组分之间的关系,同时分析其对MetS的预测能力。方法本研究前瞻性收集2023年6月至2024年6月于牡丹江医科大学附属第二医院内分泌科就诊的MetS患者,同时匹配相似数量的健康人群作为对照组。利用mDixon-Quant检查获取所有研究对象的胰腺FF与T2^(*)弛豫时间,收集体重、腰围、血糖、甘油三酯等代谢组分结果,比较两组间各指标的差异,分析MetS患者的胰腺FF、T2^(*)与各代谢组分的相关性。将组间差异比较有统计学意义的指标纳入多因素二元logistic回归分析中,同时加入能反映胰腺铁脂交互作用的FF×T2^(*)进而获取MetS的独立危险因素,最后采取受试者分析曲线(Receiver operating characteristic,ROC)分析各指标对MetS的预测能力。结果组间差异比较结果显示Mets组患者的腰围、体重指数(Body mass index,BMI)、血糖、甘油三酯与高密度脂蛋白明显高于健康对照组,而T2^(*)值明显低于健康对照组。Spearman相关性分析显示,MetS组的FF与T2^(*)呈负相关,T2^(*)与血糖以及总胆固醇呈负相关。多因素二元logistic回归分析显示腰围、甘油三酯、FF×T2^(*)是MetS患者的独立危险因素。ROC曲线分析得出腰围、甘油三酯与FF×T2^(*)的曲线下面积(Area Under the Curve,AUC)分别为0.839、0.767与0.957,其中FF×T2^(*)的AUC最大,结果均具有统计学意义(P<0.05)。结论MetS的胰腺FF与T2^(*)弛豫时间呈负相关,并且FF×T2^(*)是MetS的显著危险因素,提示铁脂交互参与其病理过程,为MetS的早期预测、机制研究及干预策略制定提供重要依据。展开更多
文摘The Kop ophiolite in NE Turkey is a fragment of Neo-Tethyan forearc.It can be mainly divided into a paleo-Moho transition zone(MTZ)in the North and a harzburgitic mantle sequence in the South.Dunites are predominant in the MTZ of the Kop ophiolite,and they are locally interlayered with chromitites and enclose minor bodies of harzburgites near the petrological Moho boundary.Large Fe isotopic variations were observed for magnesiochromite(-0.14‰to 0.06‰)and olivine(-0.12‰to 0.14‰)from the MTZ chromitites,dunites and harzburgites.In individual dunite samples,magnesiochromite usually has lighter Fe isotopic compositions than olivine,which was probably caused by subsolidus Mg-Fe exchange between the two mineral phases.Both magnesiochromite and olivine display an increasing trend ofδ56Fe along a profile from chromitite todunite.This trend reflects continuous fractional crystallization in a magma chamber,which resulted in heavier Fe isotopes concentrated in the evolved magmas.In each cumulative cycle of chromitite and dunite,dunite was formed from relatively evolved melts after massive precipitation of magnesiochromite.Mixing of more primitive and evolved melts in the magma chamber was a potential mechanism for triggering the crystallization of magnesiochromite,generating chromitite layers in the cumulate pile.Before mixing happened,the primitive melts had reacted with mantle harzburgites during their ascendance;whereas the evolved melts may lie on the olivine-chromite cotectic near the liquidus field of pyroxene.Variable degrees of magma mixing and differentiation are expected to generate melts with differentδ56Fe values,accounting for the Fe isotopic variations of the Kop MTZ.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 30000103 and 39870480)the National Key Basic Research Special Funds (Grant No. G1999011707)by the Deutsche Forschungsgemeinschaft (DFG) for a personal grant on th
文摘The effects of ammonium (NH4+-N) and nitrate (NO3- - N) were examined on Fe fractions and FeCN (ferricyanide) reductase activity in intact root tips (0-3 cm) of young maize (Zea mays L. cv. Lenz) in solution culture by using short-term experiment under controlled Fe deficiency conditions (containing high HCO3- concentration in pre-culture solution). The results showed that Fe(Ⅱ) concentrations in root tip apoplast of maize were only 20-40 nmol/g FW which accounted for 7%-13% of total Fe. Most of Fe in root tips existed as Fe(Ⅲ) compounds. Imposition of the roots to NH4+ - N or NO3- - N for 60 min led to an increase of Fe(Ⅱ) in root tip apoplast. NH4+ - N led to an increased concentration of Fe(Ⅱ) and exchangeable Fe (Fe(Ⅱ) and Fe (Ⅲ)) in root tips, while NO3- - N increased FeCN reductase activity. The relationship between pH and Fe fractions, FeCN reductase activity was also discussed.
基金supported by the National Natural Science Foundation of China(nos.41171198,41403079)the Chongqing Research Program of Basic Research and Frontier Technology(no.cstc2015jcyj A20021)the Fundamental Research Funds for the Central Universities of Ministry of Education of China(no.XDJK2015B035)
文摘The phosphorus（P） fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid（HA） complexes were analyzed using the ultrafiltration method in this study.With an initial P concentration of 20 mg/L（I =0.01 mol/L and pH = 7）,it was shown that the colloid（1 kDa-0.45 μm） component of P accounted for 10.6%,11.6%,6.5%,and 4.0%of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite（FH）,goethite（GE）,ferrihydrite-humic acid complex（FH-HA）,goethite-humic acid complex（GE-HA）,respectively.The 〈1 kDa component of P was still the predominant fraction in the supernatant,and underestimated colloidal P accounted for 2.2%,55.1%,45.5%,and 38.7%of P adsorption onto the solid surface of FH,FH-HA,GE and GE-HA,respectively.Thus,the colloid P could not be neglected.Notably,it could be interpreted that Fe3＋ hydrolysis from the adsorbents followed by the formation of colloidal hydrous ferric oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant.And colloidal adsorbent particles co-existing in the supernatant were another important reason for it.Additionally,dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant.Ultimately,we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P,even when considering other contaminants such as organic pollutants,heavy metal ions,and arsenate at the sediment/soil-water interface in the real environment.
文摘目的探究基于mDixon-Quant的胰腺脂肪分数(Fat faction,FF)、T2^(*)弛豫时间与代谢综合征(Metabolic syndrome,MetS)患者各代谢组分之间的关系,同时分析其对MetS的预测能力。方法本研究前瞻性收集2023年6月至2024年6月于牡丹江医科大学附属第二医院内分泌科就诊的MetS患者,同时匹配相似数量的健康人群作为对照组。利用mDixon-Quant检查获取所有研究对象的胰腺FF与T2^(*)弛豫时间,收集体重、腰围、血糖、甘油三酯等代谢组分结果,比较两组间各指标的差异,分析MetS患者的胰腺FF、T2^(*)与各代谢组分的相关性。将组间差异比较有统计学意义的指标纳入多因素二元logistic回归分析中,同时加入能反映胰腺铁脂交互作用的FF×T2^(*)进而获取MetS的独立危险因素,最后采取受试者分析曲线(Receiver operating characteristic,ROC)分析各指标对MetS的预测能力。结果组间差异比较结果显示Mets组患者的腰围、体重指数(Body mass index,BMI)、血糖、甘油三酯与高密度脂蛋白明显高于健康对照组,而T2^(*)值明显低于健康对照组。Spearman相关性分析显示,MetS组的FF与T2^(*)呈负相关,T2^(*)与血糖以及总胆固醇呈负相关。多因素二元logistic回归分析显示腰围、甘油三酯、FF×T2^(*)是MetS患者的独立危险因素。ROC曲线分析得出腰围、甘油三酯与FF×T2^(*)的曲线下面积(Area Under the Curve,AUC)分别为0.839、0.767与0.957,其中FF×T2^(*)的AUC最大,结果均具有统计学意义(P<0.05)。结论MetS的胰腺FF与T2^(*)弛豫时间呈负相关,并且FF×T2^(*)是MetS的显著危险因素,提示铁脂交互参与其病理过程,为MetS的早期预测、机制研究及干预策略制定提供重要依据。
