化石通常赋存在年代久远的地层中,其形成所需的时间是一个尚不清楚的问题.对浙江省朱家尖岛发现的"石化木"———一种形似珊瑚的铁、锰质岩石,进行了元素地球化学、微生物矿物学等的研究,发现它们是在微生物成矿作用下,经Fe,M...化石通常赋存在年代久远的地层中,其形成所需的时间是一个尚不清楚的问题.对浙江省朱家尖岛发现的"石化木"———一种形似珊瑚的铁、锰质岩石,进行了元素地球化学、微生物矿物学等的研究,发现它们是在微生物成矿作用下,经Fe,Mn分异和矿化过程形成的."石化木"炭芯年龄为5 600 cal yr B P,这表明,该石化木正在进行化石化的过程,可能是迄今为止发现的最年轻的石化木.该发现对于解释这种自然现象并说明地球历史时期的化石及其形成过程和外生铁、锰矿床的成因有重要意义.展开更多
The bioleaching of two different types of low-grade copper tailings,acid-leaching tailings(ALT)and copper flotation tailings(CFT)by mixed moderate thermophiles,and the variation of mineralogical and microbiological ch...The bioleaching of two different types of low-grade copper tailings,acid-leaching tailings(ALT)and copper flotation tailings(CFT)by mixed moderate thermophiles,and the variation of mineralogical and microbiological characteristics during their dissolution processes were comparatively investigated.Results showed that bioleaching behaviors of the two types of tailings were significantly different.In ALT bioleaching,lower redox potential,higher[Fe3+]/[Fe2+]ratio and higher cell density in solution were obtained.These resulted in higher total copper,primary copper sulfide and secondary copper sulfide extractions,compared with CFT bioleaching.X-ray diffraction analysis suggested that gypsum and some metal organic complexes were detected in CFT bioleaching,which could cause the sluggish oxidation of sulphide minerals.The shifts of microbial community in the leachates and leaching residues varied greatly between ALT and CFT bioleaching.The percentage of iron-oxidizing bacteria in ALT bioleaching was higher than that of CFT,but the sulfur-oxidizing bacteria percentage was the opposite.The archaeon F.thermophilum L1 was detected in ALT but not in CFT.展开更多
Objective： To study the change and relationship among bone mineral density （BMD）, collagen composition and biomechanical properties of the callus in the healing process of osteoporotic fracture. Methods： The oste...Objective： To study the change and relationship among bone mineral density （BMD）, collagen composition and biomechanical properties of the callus in the healing process of osteoporotic fracture. Methods： The osteoporotic rat model and fracture model were established through bilateral ovariectomy （OV＇X） and osteotomy of the middle shaft of the right hind tibiae, respectively. Ninety female SD rats were randomly divided into OVX group and sham group. With the samples of blood and callus, roentgenoraphic and histological observation were performed for the assessment of the healing progress of the fracture, and the serum concentration of TRAP-5b, proportion of type I collagen, BMD and biomechanical properties of the callus were measured. Results： The OVX group experienced a significant delay of fracture healing. The mean serum concentration of TRAP-5b of rats in the OVX group was much higher than that in the sham group after the operation （P 〈 0.05）, but the difference at the same time point after fracture was smaller than that before fracture （P 〈 0.05）. The BMD of the callus in both groups reached the peak value at the 6 th week after fracture while the proportion of the type I collagen and the biomechanical strength reached the peak at the 8th week. Conclusions. The deficiency of estrogen after the ovariectomy could induce the up-regulation of the osteoclasts activities, whereas the potency of further activation after fracture was depressed. Although the synthesis of collagen together with its mineralization determines the biomechanical properties of new bone, the accumulation of collagen could be assessed as an index in the prediction of biomechanical strength of bones independent of the bone mineral deposition.展开更多
Plant invasions can affect soil properties in the invaded habitat by altering the biotic and abiotic nature of soils through positive or negative plant–soil feedback.Litter decomposition from many invasive species en...Plant invasions can affect soil properties in the invaded habitat by altering the biotic and abiotic nature of soils through positive or negative plant–soil feedback.Litter decomposition from many invasive species enhanced soil nutrients,thereby decreasing native plant diversity and leading to further plant invasions.Here,we examined the impact of litter decomposition from an invasive plant(Sphagneticola trilobata)in a range of soils at varying depths on growth and physiology of its native congener(Sphagneticola calendulacea).We added litter from S.trilobata to each soil type at different depths(0,2,4 and 6 cm).Plants of S.calendulacea were grown in each treatment,and morphological and physiological parameters were measured at the end of the growing period.All soils treated with litter displayed increases in soil nutrients at depths of 2 and 4 cm;while most growth traits,leaf chlorophyll and leaf nitrogen of S.calendulacea decreased at the same soil depths.Therefore,litter decomposition from invasive S.trilobata resulted in a positive plant–soil feedback for soil nutrients,and a negative plant–soil feedback for growth in native S.calendulacea.Our findings also suggest that the effects of litter decomposition from an invasive plant on soils and native species can vary significantly depending on the soil depth at which the litter is deposited.Future studies should focus on plant–soil feedback for more native and invasive species in invaded habitats,and the effects of invasive litter in more soil types and at greater soil depths.展开更多
文摘化石通常赋存在年代久远的地层中,其形成所需的时间是一个尚不清楚的问题.对浙江省朱家尖岛发现的"石化木"———一种形似珊瑚的铁、锰质岩石,进行了元素地球化学、微生物矿物学等的研究,发现它们是在微生物成矿作用下,经Fe,Mn分异和矿化过程形成的."石化木"炭芯年龄为5 600 cal yr B P,这表明,该石化木正在进行化石化的过程,可能是迄今为止发现的最年轻的石化木.该发现对于解释这种自然现象并说明地球历史时期的化石及其形成过程和外生铁、锰矿床的成因有重要意义.
基金Projects(31570113,41573072)supported by the National Natural Science Foundation of China
文摘The bioleaching of two different types of low-grade copper tailings,acid-leaching tailings(ALT)and copper flotation tailings(CFT)by mixed moderate thermophiles,and the variation of mineralogical and microbiological characteristics during their dissolution processes were comparatively investigated.Results showed that bioleaching behaviors of the two types of tailings were significantly different.In ALT bioleaching,lower redox potential,higher[Fe3+]/[Fe2+]ratio and higher cell density in solution were obtained.These resulted in higher total copper,primary copper sulfide and secondary copper sulfide extractions,compared with CFT bioleaching.X-ray diffraction analysis suggested that gypsum and some metal organic complexes were detected in CFT bioleaching,which could cause the sluggish oxidation of sulphide minerals.The shifts of microbial community in the leachates and leaching residues varied greatly between ALT and CFT bioleaching.The percentage of iron-oxidizing bacteria in ALT bioleaching was higher than that of CFT,but the sulfur-oxidizing bacteria percentage was the opposite.The archaeon F.thermophilum L1 was detected in ALT but not in CFT.
文摘Objective： To study the change and relationship among bone mineral density （BMD）, collagen composition and biomechanical properties of the callus in the healing process of osteoporotic fracture. Methods： The osteoporotic rat model and fracture model were established through bilateral ovariectomy （OV＇X） and osteotomy of the middle shaft of the right hind tibiae, respectively. Ninety female SD rats were randomly divided into OVX group and sham group. With the samples of blood and callus, roentgenoraphic and histological observation were performed for the assessment of the healing progress of the fracture, and the serum concentration of TRAP-5b, proportion of type I collagen, BMD and biomechanical properties of the callus were measured. Results： The OVX group experienced a significant delay of fracture healing. The mean serum concentration of TRAP-5b of rats in the OVX group was much higher than that in the sham group after the operation （P 〈 0.05）, but the difference at the same time point after fracture was smaller than that before fracture （P 〈 0.05）. The BMD of the callus in both groups reached the peak value at the 6 th week after fracture while the proportion of the type I collagen and the biomechanical strength reached the peak at the 8th week. Conclusions. The deficiency of estrogen after the ovariectomy could induce the up-regulation of the osteoclasts activities, whereas the potency of further activation after fracture was depressed. Although the synthesis of collagen together with its mineralization determines the biomechanical properties of new bone, the accumulation of collagen could be assessed as an index in the prediction of biomechanical strength of bones independent of the bone mineral deposition.
基金supported by the National Natural Science Foundation of China(31971427,32071521,31770446)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment.
文摘Plant invasions can affect soil properties in the invaded habitat by altering the biotic and abiotic nature of soils through positive or negative plant–soil feedback.Litter decomposition from many invasive species enhanced soil nutrients,thereby decreasing native plant diversity and leading to further plant invasions.Here,we examined the impact of litter decomposition from an invasive plant(Sphagneticola trilobata)in a range of soils at varying depths on growth and physiology of its native congener(Sphagneticola calendulacea).We added litter from S.trilobata to each soil type at different depths(0,2,4 and 6 cm).Plants of S.calendulacea were grown in each treatment,and morphological and physiological parameters were measured at the end of the growing period.All soils treated with litter displayed increases in soil nutrients at depths of 2 and 4 cm;while most growth traits,leaf chlorophyll and leaf nitrogen of S.calendulacea decreased at the same soil depths.Therefore,litter decomposition from invasive S.trilobata resulted in a positive plant–soil feedback for soil nutrients,and a negative plant–soil feedback for growth in native S.calendulacea.Our findings also suggest that the effects of litter decomposition from an invasive plant on soils and native species can vary significantly depending on the soil depth at which the litter is deposited.Future studies should focus on plant–soil feedback for more native and invasive species in invaded habitats,and the effects of invasive litter in more soil types and at greater soil depths.
