The depression of pyrite in marmatite flotation by sodium glycerine-xanthate （SGX） was investigated through microflotation, zeta potential and adsorption measurements. The flotation tests of mineral show that in the...The depression of pyrite in marmatite flotation by sodium glycerine-xanthate （SGX） was investigated through microflotation, zeta potential and adsorption measurements. The flotation tests of mineral show that in the presence of SGX, marmatite can be activated by Cu^2＋ and shows good flotability, while pyrite cannot be activated and therefore shows poor flotability. At the pH value range from 4 to 11, the flotation selectivity between marmatite and pyrite is obvious when the SGX concentration is below 50 mg/L. The depression mechanism of SGX on sulfide minerals is discussed based on zeta potential and adsorption isotherm. Zeta potential measurement demonstrates that in the presence of Cu^2＋, SGX can strongly adsorb on the surface of pyrite, while it cannot adsorb on the surface of marmatite. The results of adsorption isotherms show that the adsorption density of SGX on pyrite is greater.展开更多
In plant, iron uptake and homeostasis are tightly regulated to ensure its absorption from soil and to avoid excess iron in the cell. Many genes involved in this process have been identified during past several years, ...In plant, iron uptake and homeostasis are tightly regulated to ensure its absorption from soil and to avoid excess iron in the cell. Many genes involved in this process have been identified during past several years, but there are many problems remain unsolved in the genetic regulation of whole plant iron trafficking and allocation. MYB transcription factors contain tandem repeats of a -50 amino acid DNA-binding motif （R） and are involved in the regulation of many aspects of plant development, hormone signaling and metabolism. Here, we report that the ectopic expression of orchid R2R3-MYB gene DwMYB2 in Arabidopsis thaliana confers the transgenic plants hypersensitivity to iron deficiency. In DwMYB2 transgenic plants, the iron content in root is two-fold higher compared to that in wild-type root, while the reverse is true in shoot. This imbalance of iron content in root and shoot suggested that the translocation of iron from root to shoot was affected by the expression of DwMYB2 in the transgenic plants. Consistently, gene chip and reverse transcription-polymerase chain reaction analysis revealed that the ferric-chelate reductase gene, AtFRO2, and the iron transporter gene, AtlRT1 and AtlRT2, are up-regulated by DwMYB2 expression, while other potential iron transporters such as AtlREG1, AtFRD3 and NRAMP1 are down-regulated. In addition, the expression of several putative peptide transporters and transcription factors are also altered in the 35S：：DwMYB2 transgenic lines. These data provide us insight into the whole plant translocation of iron and identify candidate genes for iron homeostasis in plants despite the fact that a heterologous gene was expressed.展开更多
NiFe(oxy)hydroxides nanosheets were synthesized on nickel foams via co-precipitation and electrochemical activation. It is found that the phosphate precursors(Na_(3)PO_(4), Na_(2)HPO_(4)and NaH_(2)PO_(4)) have diverse...NiFe(oxy)hydroxides nanosheets were synthesized on nickel foams via co-precipitation and electrochemical activation. It is found that the phosphate precursors(Na_(3)PO_(4), Na_(2)HPO_(4)and NaH_(2)PO_(4)) have diverse effects on the morphology and thus the oxygen evolution reaction activity of the formed final catalysts. The resulting NiFe(oxy)hydroxides nanosheets prepared with Na_(2)HPO_(4)demonstrate a low overpotential of 205 m V to achieve a current density of 50 mA/cm^(2) with a Tafel slope down to 30 mV/dec in 1 mol/L KOH, and remain stable for 20 h during stability test.展开更多
Railway accident prevention and protection are a key part of a wider picture of transport safety. The rail sector thus needs to improve its knowledge of trespassing and suicide, including at level crossing, in order t...Railway accident prevention and protection are a key part of a wider picture of transport safety. The rail sector thus needs to improve its knowledge of trespassing and suicide, including at level crossing, in order to work out suitable responses by analyzing measures already taken in various countries, Governments, the rail industry and road organizations have been implementing a variety of countermeasures for many years to improve railway safety. These actions are substantial and have resulted in a continuing decrease in the number and the severity of accidents. This paper presents existing suitable techniques that are used in the preventative measures targeted to reduce railway suicides, trespassing and level crossing user accidents. It describes them in terms of their capability to effectively reduce accidents, their cost-effectiveness and their integration within the railway transport system as a whole.展开更多
Oxygen evolution reaction （OER） electrolysis, as an important reaction involved in water splitting and rechargeable metal-air batteries, has attracted increasing attention for clean energy generation and efficient e...Oxygen evolution reaction （OER） electrolysis, as an important reaction involved in water splitting and rechargeable metal-air batteries, has attracted increasing attention for clean energy generation and efficient energy storage. Nickel/iron （NiFe）-based compounds have been known as active OER catalysts since the last century, and renewed interest has been witnessed in recent years on developing advanced NiFe-based materials for better activity and stability. In this review, we present the early discovery and recent progress on NiFe-based OER electrocatalysts in terms of chemical properties, synthetic methodologies and catalytic performances. The advantages and disadvantages of each class of NiFe-based compounds are summarized, including NiFe alloys, electrodeposited films and layered double hydroxide nanoplates. Some mechanistic studies of the active phase of NiFe-based compounds are introduced and discussed to give insight into the nature of active catalytic sites, which could facilitate further improving NiFe based OER electrocatalysts. Finally, some applications of NiFe- based compounds for OER are described, including the development of an electrolyzer operating with a single AAA battery with voltage below 1.5 V and high performance rechargeable Zn-air batteries.展开更多
To prepare and characterize the ferromagnetic fluid of Fe304 modified by carboxyl PEG （FF/carboxyl PEG） for hyperthermia of tumor, the magnetic nanoparticles （NPs） of Fe304 were prepared by chemical co-precipitati...To prepare and characterize the ferromagnetic fluid of Fe304 modified by carboxyl PEG （FF/carboxyl PEG） for hyperthermia of tumor, the magnetic nanoparticles （NPs） of Fe304 were prepared by chemical co-precipitation method, and then modified with carboxyl PEG. The iron content of FFs was determined by spectrophotometric method using o-phenanthroline. The stability of FF/carboxyl PEG was assessed by the sedimentation method. FF/carboxyl PEG was characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, infrared spectrometry （IR） and vibrating sample magnetometer （VSM）. Heating effect of FF/carboxyl PEG was measured in an alternating magnetic field in vitro. The stability of FF/carboxyl PEG was much better than that of unmodified ferromagnetic fluid. FF/carboxyl PEG was proved to be composed of Fe304 by both XRD and IR. TEM showed that the ferromagnetic particles were well-dispersed. The average particle size was calculated as 5 nm by XRD. The saturation magnetization and residual magnetization of FF/carboxyl PEG were 47.01 and 3.41 emu/g, respectively. The coercive force was 6.70e. The specific absorption rate （SAR） of the FF/carboxyl PEG was 63.0 W/g[Fe]. The FF/carboxyl PEG shows the promise for hyperthermia of tumor.展开更多
基金Project (50774094) supported by the National Natural Science Foundation of China
文摘The depression of pyrite in marmatite flotation by sodium glycerine-xanthate （SGX） was investigated through microflotation, zeta potential and adsorption measurements. The flotation tests of mineral show that in the presence of SGX, marmatite can be activated by Cu^2＋ and shows good flotability, while pyrite cannot be activated and therefore shows poor flotability. At the pH value range from 4 to 11, the flotation selectivity between marmatite and pyrite is obvious when the SGX concentration is below 50 mg/L. The depression mechanism of SGX on sulfide minerals is discussed based on zeta potential and adsorption isotherm. Zeta potential measurement demonstrates that in the presence of Cu^2＋, SGX can strongly adsorb on the surface of pyrite, while it cannot adsorb on the surface of marmatite. The results of adsorption isotherms show that the adsorption density of SGX on pyrite is greater.
文摘In plant, iron uptake and homeostasis are tightly regulated to ensure its absorption from soil and to avoid excess iron in the cell. Many genes involved in this process have been identified during past several years, but there are many problems remain unsolved in the genetic regulation of whole plant iron trafficking and allocation. MYB transcription factors contain tandem repeats of a -50 amino acid DNA-binding motif （R） and are involved in the regulation of many aspects of plant development, hormone signaling and metabolism. Here, we report that the ectopic expression of orchid R2R3-MYB gene DwMYB2 in Arabidopsis thaliana confers the transgenic plants hypersensitivity to iron deficiency. In DwMYB2 transgenic plants, the iron content in root is two-fold higher compared to that in wild-type root, while the reverse is true in shoot. This imbalance of iron content in root and shoot suggested that the translocation of iron from root to shoot was affected by the expression of DwMYB2 in the transgenic plants. Consistently, gene chip and reverse transcription-polymerase chain reaction analysis revealed that the ferric-chelate reductase gene, AtFRO2, and the iron transporter gene, AtlRT1 and AtlRT2, are up-regulated by DwMYB2 expression, while other potential iron transporters such as AtlREG1, AtFRD3 and NRAMP1 are down-regulated. In addition, the expression of several putative peptide transporters and transcription factors are also altered in the 35S：：DwMYB2 transgenic lines. These data provide us insight into the whole plant translocation of iron and identify candidate genes for iron homeostasis in plants despite the fact that a heterologous gene was expressed.
基金supported by the National Natural Science Foundation of China (Nos. 11904411, 52072308)the Fundamental Research Funds for the Central Universities, China (Nos. 3102021MS0404, 3102019JC001)。
文摘NiFe(oxy)hydroxides nanosheets were synthesized on nickel foams via co-precipitation and electrochemical activation. It is found that the phosphate precursors(Na_(3)PO_(4), Na_(2)HPO_(4)and NaH_(2)PO_(4)) have diverse effects on the morphology and thus the oxygen evolution reaction activity of the formed final catalysts. The resulting NiFe(oxy)hydroxides nanosheets prepared with Na_(2)HPO_(4)demonstrate a low overpotential of 205 m V to achieve a current density of 50 mA/cm^(2) with a Tafel slope down to 30 mV/dec in 1 mol/L KOH, and remain stable for 20 h during stability test.
文摘Railway accident prevention and protection are a key part of a wider picture of transport safety. The rail sector thus needs to improve its knowledge of trespassing and suicide, including at level crossing, in order to work out suitable responses by analyzing measures already taken in various countries, Governments, the rail industry and road organizations have been implementing a variety of countermeasures for many years to improve railway safety. These actions are substantial and have resulted in a continuing decrease in the number and the severity of accidents. This paper presents existing suitable techniques that are used in the preventative measures targeted to reduce railway suicides, trespassing and level crossing user accidents. It describes them in terms of their capability to effectively reduce accidents, their cost-effectiveness and their integration within the railway transport system as a whole.
文摘Oxygen evolution reaction （OER） electrolysis, as an important reaction involved in water splitting and rechargeable metal-air batteries, has attracted increasing attention for clean energy generation and efficient energy storage. Nickel/iron （NiFe）-based compounds have been known as active OER catalysts since the last century, and renewed interest has been witnessed in recent years on developing advanced NiFe-based materials for better activity and stability. In this review, we present the early discovery and recent progress on NiFe-based OER electrocatalysts in terms of chemical properties, synthetic methodologies and catalytic performances. The advantages and disadvantages of each class of NiFe-based compounds are summarized, including NiFe alloys, electrodeposited films and layered double hydroxide nanoplates. Some mechanistic studies of the active phase of NiFe-based compounds are introduced and discussed to give insight into the nature of active catalytic sites, which could facilitate further improving NiFe based OER electrocatalysts. Finally, some applications of NiFe- based compounds for OER are described, including the development of an electrolyzer operating with a single AAA battery with voltage below 1.5 V and high performance rechargeable Zn-air batteries.
文摘To prepare and characterize the ferromagnetic fluid of Fe304 modified by carboxyl PEG （FF/carboxyl PEG） for hyperthermia of tumor, the magnetic nanoparticles （NPs） of Fe304 were prepared by chemical co-precipitation method, and then modified with carboxyl PEG. The iron content of FFs was determined by spectrophotometric method using o-phenanthroline. The stability of FF/carboxyl PEG was assessed by the sedimentation method. FF/carboxyl PEG was characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, infrared spectrometry （IR） and vibrating sample magnetometer （VSM）. Heating effect of FF/carboxyl PEG was measured in an alternating magnetic field in vitro. The stability of FF/carboxyl PEG was much better than that of unmodified ferromagnetic fluid. FF/carboxyl PEG was proved to be composed of Fe304 by both XRD and IR. TEM showed that the ferromagnetic particles were well-dispersed. The average particle size was calculated as 5 nm by XRD. The saturation magnetization and residual magnetization of FF/carboxyl PEG were 47.01 and 3.41 emu/g, respectively. The coercive force was 6.70e. The specific absorption rate （SAR） of the FF/carboxyl PEG was 63.0 W/g[Fe]. The FF/carboxyl PEG shows the promise for hyperthermia of tumor.
