Laser ablation–inductively coupled plasma–mass spectrometry（LA–ICP–MS） was used to determine the trace element concentrations of magnetite from the Heifengshan, Shuangfengshan, and Shaquanzi Fe（–Cu） deposits ...Laser ablation–inductively coupled plasma–mass spectrometry（LA–ICP–MS） was used to determine the trace element concentrations of magnetite from the Heifengshan, Shuangfengshan, and Shaquanzi Fe（–Cu） deposits in the Eastern Tianshan Orogenic Belt. The magnetite from these deposits typically contains detectable Mg, Al, Ti, V, Cr, Mn, Co, Ni, Zn and Ga. The trace element contents in magnetite generally vary less than one order of magnitude. The subtle variations of trace element concentrations within a magnetite grain and between the magnetite grains in the same sample probably indicate local inhomogeneity of ore–forming fluids. The variations of Co in magnetite between samples are probably due to the mineral proportion of magnetite and pyrite. Factor analysis has discriminated three types of magnetite： Ni–Mn–V–Ti（Factor 1）, Mg–Al–Zn（Factor 2）, and Ga– Co（Factor 3） magnetite. Magnetite from the Heifengshan and Shuangfengshan Fe deposits has similar normalized trace element spider patterns and cannot be discriminated according to these factors. However, magnetite from the Shaquanzi Fe–Cu deposit has affinity to Factor 2 with lower Mg and Al but higher Zn concentrations, indicating that the ore–forming fluids responsible for the Fe–Cu deposit are different from those for Fe deposits. Chemical composition of magnetite indicates that magnetite from these Fe（–Cu） deposits was formed by hydrothermal processes rather than magmatic differentiation. The formation of these Fe（–Cu） deposits may be related to felsic magmatism.展开更多
Objective This paper aims to elucidate the combined toxicity of magnetite nanoparticles/Chromium [MNPs/Cr（Ⅵ）] adducts. Methods The HEK293 cell was exposed to either Cr（Ⅵ） or MNPs, or their adducts MNPs/Cr（Ⅵ）....Objective This paper aims to elucidate the combined toxicity of magnetite nanoparticles/Chromium [MNPs/Cr（Ⅵ）] adducts. Methods The HEK293 cell was exposed to either Cr（Ⅵ） or MNPs, or their adducts MNPs/Cr（Ⅵ）. The cytotoxicity was evaluated by assessing the cell viability, apoptosis, oxidative stress induction, and cellular uptake. Results The toxicity of formed adducts is significantly reduced when compared to Cr（Ⅵ） anions. We found that the cellular uptake of MNPs/Cr（Ⅵ） adduct was rare, only few particles were endocytosed from the extracellular fluid and not accumulated in the cell nucleus. On the other hand, the Cr（Ⅵ） anions entered cells, generated oxidative stress, induced cell apoptosis, and caused cytotoxicity. Conclusion The results showed minor effects of the nanoadducts on the tested cells and supported that magnetite nanoparticles could be implemented in the wastewater treatment process in which advantageous properties outweigh the risks.展开更多
One simple and environmental friendly synthesis strategy for preparing low-cost magnetic Fe3C@C materials has been facilely developed using a modified sol-gel approach,wherein natural magnetite acted as the iron sourc...One simple and environmental friendly synthesis strategy for preparing low-cost magnetic Fe3C@C materials has been facilely developed using a modified sol-gel approach,wherein natural magnetite acted as the iron source.A chelating polycarboxylic acid such as citric acid(CA)was employed as the carbon source,and it dissolved Fe very effectively,Fe3O4 and natural magnetite to composite an iron-citrate complex with the assistance of ammonium hydroxide.The core-shell structure of the as-prepared nanocomposites was formed directly by high-temperature pyrolysis.The Fe3C@C materials exhibited superparamagnetic properties(38.09 emu/mg),suggesting potential applications in biomedicine,environment,absorption,catalysis,etc.展开更多
In the present work, magnetite (Fe<sub>3</sub>O<sub>4</sub>) nanoparticles have been prepared by a simple chemical method. Polymer nanocomposites based on the blend between poly vinylamine fluo...In the present work, magnetite (Fe<sub>3</sub>O<sub>4</sub>) nanoparticles have been prepared by a simple chemical method. Polymer nanocomposites based on the blend between poly vinylamine fluoride (PVDF) and (methyl methacrylate) (PMMA) doped with different concentrations of Fe<sub>3</sub>O<sub>4</sub> nanoparticles have been prepared. The structural, optical, and magnetization properties of the nanocomposite samples were studied using suitable techniques. The X-ray study reflected that the cubic spinal structure of pure Fe<sub>3</sub>O<sub>4</sub> crystal. No small peaks or ripples were found in the X-ray spectra, conforming to good dispersion of Fe<sub>3</sub>O<sub>4</sub> within PVDF/PMMA matrices. The FT-IR analysis demonstrated the miscibility between the PVDF and PMMA blend with the interaction between the polymer blend and Fe<sub>3</sub>O<sub>4</sub>. The values of the band gap from UV-Vis study were decreased up to 4.21 eV, 3.01 eV for direct and indirect measurements, respectively. The magnetization was measured as a function of the applied magnetic field in the range of −2000 - 2000 Oersted. The curves of the magnetization indicated a paramagnetic behavior of pure Fe<sub>3</sub>O<sub>4</sub> nanoparticles and PVDF/PMMA-Fe<sub>3</sub>O<sub>4</sub> nanocomposites. The values of saturation magnetization for pure Fe<sub>3</sub>O<sub>4</sub> are nearly 75 emu/g, exhibiting a paramagnetic behavior, and it is decreased with the increase of Fe<sub>3</sub>O<sub>4</sub> content.展开更多
Monodisperse hollow magnetite microspheres were successfully synthesized by an one-step process through a tem-plate-free hydrothermal approach employing simultaneously a mixture of FeCl3.6H2O and ferrocene as precurso...Monodisperse hollow magnetite microspheres were successfully synthesized by an one-step process through a tem-plate-free hydrothermal approach employing simultaneously a mixture of FeCl3.6H2O and ferrocene as precursor and a propylene glycol-isopropanol mixture as solvent. The morphologies and properties of the magnetite microspheres were characterized by X-ray diffraction (XRD), Raman and infrared spectroscopy, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), adsorption of nitrogen (BET method) and SQUID magnetometry. The results show that the microspheres consist of a single crystalline phase of magnetite. On the other hand, the size and the internal hollow of the microspheres depend on the temperature of growth and can be tuned by modifying the synthesis conditions.展开更多
The uncommon Mg-rich and Ti-poor Zhaoanzhuang serpentine-magnetite ores within Taihua Group of the North China Craton （NCC） remain unclear whether the protolith was sourced from ultramafic rocks or chemical sediment...The uncommon Mg-rich and Ti-poor Zhaoanzhuang serpentine-magnetite ores within Taihua Group of the North China Craton （NCC） remain unclear whether the protolith was sourced from ultramafic rocks or chemical sedimentary sequences. Here we present integrated petrographic and geochemical studies to characterize the protoliths and to gain insights on the ore-forming processes. Iron ores mainly contain low-Ti magnetite （TiO2 -0.1wt%） and serpentine （Mg#=92.42-96.55）, as well as residual olivine （Fo=89-90）, orthopyroxene （En=89-90） and hornblende. Magnetite in the iron ores shows lower AI, Sc, Ti, Cr, Zn relative to that from ultramafic Fe-Ti-V iron ores, but similar to that from metamorphic chemical sedimentary iron deposit. In addition, interstitial minerals of dolomite, calcite, apatite and anhydrite are intergrown with magnetite and serpentine, revealing they were metamorphic, but not magmatic or late hydrothermal minerals. Wall rocks principally contain magnesian silicates of olivine （Fo=83-87）, orthopyroxene （En=82-86）, humite （Mg#=82-84） and hornblende [XMg=0.87--0.96]. Dolomite, apatite and anhydrite together with minor magnetite, thorianite （Th-rich oxide） and monazite （LREE-rich phosphate） are often seen as relicts or inclusions within magnesian silicates in the wall rocks, revealing that they were primary or earlier metamorphic minerals than magnesian silicates. And olivine exists as subhedral interstitial texture between hornblende, which shows later formation of olivine than hornblende and does not conform with sequence of magmatic crystallization. All these mineralogical features thus bias towards their metamorphic, rather than magmatic origin. The dominant chemical components of the iron ores are SiO2 （4.77-25.23wt%）, Fe203T （32.9-80.39wt%） and MgO （5.72- 27.17wt%） and uniformly, those of the wall rocks are also SiO2 （16.34-48.72wt%）, MgO （16.71- 33.97wt%） and Fe203T （6.98-30.92wt%）. The striking high Fe-Mg-Si contents reveal that protolith of the Zhaoanzhuang iron deposit was more likely to be chemical sedimentary rocks. The distinct high-Mg feature and presence of abundant anhydrite possibly indicate it primarily precipitated in a confined seawater basin under an evaporitic environment. Besides, higher contents of AI, Ti, P, Th, U, Pb, REE relative to other Precambrian iron-rich chemical precipitates （BIF） suggest some clastic terrestrial materials were probably input. As a result, we think the Zhaoanzhuang iron deposit had experienced the initial Fe-Mg-Si marine precipitation, followed by further Mg enrichment through marine evaporated process, subsequent high-grade metamorphism and late-stage hydrothermal fluid modification.展开更多
Magnetite nanoparticles (MNPs) and magnetite/silver nanoparticles (M/Ag NPs) were synthesized by chemical co-precipitation of Fe<sup>2+</sup> and Fe<sup>3+</sup>. In case of M/Ag NPs, MNPs (cor...Magnetite nanoparticles (MNPs) and magnetite/silver nanoparticles (M/Ag NPs) were synthesized by chemical co-precipitation of Fe<sup>2+</sup> and Fe<sup>3+</sup>. In case of M/Ag NPs, MNPs (core) were separately coated by silver metal (shell) in presence of glucose as a reducing agent. The particle size and morphology of the nanoparticles were characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Magnetic properties were investigated by vibrating sample magnetometry (VSM). The superparamagnetic natures of the nanoparticles were confirmed by the absence of the hysteresis loop. Coverage with silver produced a core-shell heterostructure which weakens magnetization of MNPs, inducing an inert character to the fnal nanostructure. The surface conjugation of MNPs with silver metal has been employed in order to improve the compatibility of magnetite nanoparticles to overcome their limitations in practical applications.展开更多
基金financially supported by the Chinese 973 project(2012CB416804)the ‘‘CAS Hundred Talents’’ Project from the Chinese Academy of Sciences(KZCX2-YW-BR-09)to Qi Liang
文摘Laser ablation–inductively coupled plasma–mass spectrometry（LA–ICP–MS） was used to determine the trace element concentrations of magnetite from the Heifengshan, Shuangfengshan, and Shaquanzi Fe（–Cu） deposits in the Eastern Tianshan Orogenic Belt. The magnetite from these deposits typically contains detectable Mg, Al, Ti, V, Cr, Mn, Co, Ni, Zn and Ga. The trace element contents in magnetite generally vary less than one order of magnitude. The subtle variations of trace element concentrations within a magnetite grain and between the magnetite grains in the same sample probably indicate local inhomogeneity of ore–forming fluids. The variations of Co in magnetite between samples are probably due to the mineral proportion of magnetite and pyrite. Factor analysis has discriminated three types of magnetite： Ni–Mn–V–Ti（Factor 1）, Mg–Al–Zn（Factor 2）, and Ga– Co（Factor 3） magnetite. Magnetite from the Heifengshan and Shuangfengshan Fe deposits has similar normalized trace element spider patterns and cannot be discriminated according to these factors. However, magnetite from the Shaquanzi Fe–Cu deposit has affinity to Factor 2 with lower Mg and Al but higher Zn concentrations, indicating that the ore–forming fluids responsible for the Fe–Cu deposit are different from those for Fe deposits. Chemical composition of magnetite indicates that magnetite from these Fe（–Cu） deposits was formed by hydrothermal processes rather than magmatic differentiation. The formation of these Fe（–Cu） deposits may be related to felsic magmatism.
文摘Objective This paper aims to elucidate the combined toxicity of magnetite nanoparticles/Chromium [MNPs/Cr（Ⅵ）] adducts. Methods The HEK293 cell was exposed to either Cr（Ⅵ） or MNPs, or their adducts MNPs/Cr（Ⅵ）. The cytotoxicity was evaluated by assessing the cell viability, apoptosis, oxidative stress induction, and cellular uptake. Results The toxicity of formed adducts is significantly reduced when compared to Cr（Ⅵ） anions. We found that the cellular uptake of MNPs/Cr（Ⅵ） adduct was rare, only few particles were endocytosed from the extracellular fluid and not accumulated in the cell nucleus. On the other hand, the Cr（Ⅵ） anions entered cells, generated oxidative stress, induced cell apoptosis, and caused cytotoxicity. Conclusion The results showed minor effects of the nanoadducts on the tested cells and supported that magnetite nanoparticles could be implemented in the wastewater treatment process in which advantageous properties outweigh the risks.
基金supported by the National Natural Science Foundation of China(No.51876046 and No.51711540032)。
文摘One simple and environmental friendly synthesis strategy for preparing low-cost magnetic Fe3C@C materials has been facilely developed using a modified sol-gel approach,wherein natural magnetite acted as the iron source.A chelating polycarboxylic acid such as citric acid(CA)was employed as the carbon source,and it dissolved Fe very effectively,Fe3O4 and natural magnetite to composite an iron-citrate complex with the assistance of ammonium hydroxide.The core-shell structure of the as-prepared nanocomposites was formed directly by high-temperature pyrolysis.The Fe3C@C materials exhibited superparamagnetic properties(38.09 emu/mg),suggesting potential applications in biomedicine,environment,absorption,catalysis,etc.
文摘In the present work, magnetite (Fe<sub>3</sub>O<sub>4</sub>) nanoparticles have been prepared by a simple chemical method. Polymer nanocomposites based on the blend between poly vinylamine fluoride (PVDF) and (methyl methacrylate) (PMMA) doped with different concentrations of Fe<sub>3</sub>O<sub>4</sub> nanoparticles have been prepared. The structural, optical, and magnetization properties of the nanocomposite samples were studied using suitable techniques. The X-ray study reflected that the cubic spinal structure of pure Fe<sub>3</sub>O<sub>4</sub> crystal. No small peaks or ripples were found in the X-ray spectra, conforming to good dispersion of Fe<sub>3</sub>O<sub>4</sub> within PVDF/PMMA matrices. The FT-IR analysis demonstrated the miscibility between the PVDF and PMMA blend with the interaction between the polymer blend and Fe<sub>3</sub>O<sub>4</sub>. The values of the band gap from UV-Vis study were decreased up to 4.21 eV, 3.01 eV for direct and indirect measurements, respectively. The magnetization was measured as a function of the applied magnetic field in the range of −2000 - 2000 Oersted. The curves of the magnetization indicated a paramagnetic behavior of pure Fe<sub>3</sub>O<sub>4</sub> nanoparticles and PVDF/PMMA-Fe<sub>3</sub>O<sub>4</sub> nanocomposites. The values of saturation magnetization for pure Fe<sub>3</sub>O<sub>4</sub> are nearly 75 emu/g, exhibiting a paramagnetic behavior, and it is decreased with the increase of Fe<sub>3</sub>O<sub>4</sub> content.
文摘Monodisperse hollow magnetite microspheres were successfully synthesized by an one-step process through a tem-plate-free hydrothermal approach employing simultaneously a mixture of FeCl3.6H2O and ferrocene as precursor and a propylene glycol-isopropanol mixture as solvent. The morphologies and properties of the magnetite microspheres were characterized by X-ray diffraction (XRD), Raman and infrared spectroscopy, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), adsorption of nitrogen (BET method) and SQUID magnetometry. The results show that the microspheres consist of a single crystalline phase of magnetite. On the other hand, the size and the internal hollow of the microspheres depend on the temperature of growth and can be tuned by modifying the synthesis conditions.
基金funded by the National Natural Science Foundation of China (Grant No. 41672078)
文摘The uncommon Mg-rich and Ti-poor Zhaoanzhuang serpentine-magnetite ores within Taihua Group of the North China Craton （NCC） remain unclear whether the protolith was sourced from ultramafic rocks or chemical sedimentary sequences. Here we present integrated petrographic and geochemical studies to characterize the protoliths and to gain insights on the ore-forming processes. Iron ores mainly contain low-Ti magnetite （TiO2 -0.1wt%） and serpentine （Mg#=92.42-96.55）, as well as residual olivine （Fo=89-90）, orthopyroxene （En=89-90） and hornblende. Magnetite in the iron ores shows lower AI, Sc, Ti, Cr, Zn relative to that from ultramafic Fe-Ti-V iron ores, but similar to that from metamorphic chemical sedimentary iron deposit. In addition, interstitial minerals of dolomite, calcite, apatite and anhydrite are intergrown with magnetite and serpentine, revealing they were metamorphic, but not magmatic or late hydrothermal minerals. Wall rocks principally contain magnesian silicates of olivine （Fo=83-87）, orthopyroxene （En=82-86）, humite （Mg#=82-84） and hornblende [XMg=0.87--0.96]. Dolomite, apatite and anhydrite together with minor magnetite, thorianite （Th-rich oxide） and monazite （LREE-rich phosphate） are often seen as relicts or inclusions within magnesian silicates in the wall rocks, revealing that they were primary or earlier metamorphic minerals than magnesian silicates. And olivine exists as subhedral interstitial texture between hornblende, which shows later formation of olivine than hornblende and does not conform with sequence of magmatic crystallization. All these mineralogical features thus bias towards their metamorphic, rather than magmatic origin. The dominant chemical components of the iron ores are SiO2 （4.77-25.23wt%）, Fe203T （32.9-80.39wt%） and MgO （5.72- 27.17wt%） and uniformly, those of the wall rocks are also SiO2 （16.34-48.72wt%）, MgO （16.71- 33.97wt%） and Fe203T （6.98-30.92wt%）. The striking high Fe-Mg-Si contents reveal that protolith of the Zhaoanzhuang iron deposit was more likely to be chemical sedimentary rocks. The distinct high-Mg feature and presence of abundant anhydrite possibly indicate it primarily precipitated in a confined seawater basin under an evaporitic environment. Besides, higher contents of AI, Ti, P, Th, U, Pb, REE relative to other Precambrian iron-rich chemical precipitates （BIF） suggest some clastic terrestrial materials were probably input. As a result, we think the Zhaoanzhuang iron deposit had experienced the initial Fe-Mg-Si marine precipitation, followed by further Mg enrichment through marine evaporated process, subsequent high-grade metamorphism and late-stage hydrothermal fluid modification.
文摘Magnetite nanoparticles (MNPs) and magnetite/silver nanoparticles (M/Ag NPs) were synthesized by chemical co-precipitation of Fe<sup>2+</sup> and Fe<sup>3+</sup>. In case of M/Ag NPs, MNPs (core) were separately coated by silver metal (shell) in presence of glucose as a reducing agent. The particle size and morphology of the nanoparticles were characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Magnetic properties were investigated by vibrating sample magnetometry (VSM). The superparamagnetic natures of the nanoparticles were confirmed by the absence of the hysteresis loop. Coverage with silver produced a core-shell heterostructure which weakens magnetization of MNPs, inducing an inert character to the fnal nanostructure. The surface conjugation of MNPs with silver metal has been employed in order to improve the compatibility of magnetite nanoparticles to overcome their limitations in practical applications.
