In the past several decades, dilute magnetic semiconductors, particularly the dilute magnetic oxides have evolved into an important branch of materials science due to their potential application in spintronic devices ...In the past several decades, dilute magnetic semiconductors, particularly the dilute magnetic oxides have evolved into an important branch of materials science due to their potential application in spintronic devices combining of properties of semiconductors and ferromagnets. In spite of a major effort devoted to the mechanism of ferromagnetism with a high Curie temperature in these materials, it still remains the most controversial research topic, especially given the unexpected do ferromagnetism in a series of undoped wide-band-gap oxides films or nanostructures. Recently, an abundance of research has shown the critical role of various defects in the origin and control of spontaneous magnetic ordering, but contradicting views from intertwined theoretical calculations and experiments require more in-depth systematic research. In our previous work, considerable efforts have been focused on two major oxides, i.e. ZnO and Zr02. This review will present a summary of current experimental status of this defect-driven ferromag- netism in dilute magnetic oxides (DMOs).展开更多
In this paper, we present a proof-of-concept study of the enhancement of photocatalytic activity via a combined strategy of fabricating a visible-light responsive ternary heterostructure and improving overall photosta...In this paper, we present a proof-of-concept study of the enhancement of photocatalytic activity via a combined strategy of fabricating a visible-light responsive ternary heterostructure and improving overall photostability by incorporating magnetic zinc oxide/graphene/iron oxide (ZGF). A solvothermal approach was used to synthesize the catalyst. X-ray diffraction (XRD), scanning electron microscopic, energy dispersive X-ray, transmission electron microscopic, vibrating sample magnetometric, and ultraviolet–visible diffuse reflectance spectroscopic techniques were used to characterize the synthesized samples. The obtained optimal Zn(NO_(3))_(2) concentration, temperature, and heating duration were 0.10 mol/L, 600℃, and 1 h, respectively. The XRD pattern revealed the presence of peaks corresponding to zinc oxide, graphene, and iron oxide, indicating that the ZGF catalyst was effectively synthesized. Furthermore, when the developed ZGF was used for methylene blue dye degradation, the optimum irradiation time, dye concentration, catalyst dosage, irradiation intensity, and solution pH were 90 min, 10 mg/L, 0.03 g/L, 100 W, and 8.0, respectively. Therefore, the synthesized ZGF system could be used as a catalyst to degrade dyes in wastewater samples. This hybrid nanocomposite consisting of zinc oxide, graphene, and iron oxide could also be used as an effective photocatalytic degrader for various dye pollutants.展开更多
We investigate the ultrafast spin dynamics of an antiferromagnet in a ferromagnet/antiferromagnet heterostructure Fe/GdFeO_(3) via an all-optical method.After laser irradiation,the terahertz spin precession is hard to...We investigate the ultrafast spin dynamics of an antiferromagnet in a ferromagnet/antiferromagnet heterostructure Fe/GdFeO_(3) via an all-optical method.After laser irradiation,the terahertz spin precession is hard to be excited in a bare GdFeO_(3) without spin reorientation phase but efficiently in Fe/GdFeO_(3).Both quasi-ferromagnetic and impurity modes,as well as a phonon mode,are observed.We attribute it to the optical modification of interfacial exchange coupling between Fe and GdFeO3.Moreover,the excitation efficiency of dynamics can be modified significantly via the pump laser influence.Our results elucidate that the interfacial exchange coupling is a feasible stimulation to efficiently excite terahertz spin dynamics in antiferromagnets.It will expand the exploration of terahertz spin dynamics for antiferromagnet-based opto-spintronic devices.展开更多
This paper obtains the room temperature ferromagnetism in Sn1-x FexO2 films fabricated by the Sol-Gel method. X-ray diffraction results show that Fe doping inhibits the growth of SnO2 and Fe^3+ ions occupy the Sn sit...This paper obtains the room temperature ferromagnetism in Sn1-x FexO2 films fabricated by the Sol-Gel method. X-ray diffraction results show that Fe doping inhibits the growth of SnO2 and Fe^3+ ions occupy the Sn sites. The measurement of resistance excludes the free carrier inducing ferromagnetism. Moreover, the temperature dependence of magnetization has been better fitted by the Curie Weiss law and bound magnetic polaron (BMP) theory. An enhancement of ferromagnetism is achieved by annealing the samples with x = 7.1% in H2, and a decrease of oxygen flow rate. All these results prove that the BMP model depending on defects can explain ferromagnetism in diluted magnetic oxides.展开更多
This work reports the study concerning the structure and magnetic properties of undoped CeO_2 and Fe-doped CeO_2(Ce_(1-x) Fe_xO_2, 0.01 ≤ x ≤ 0.07) nanospheres with diameters of 100~200 nm prepared by hydrothermal m...This work reports the study concerning the structure and magnetic properties of undoped CeO_2 and Fe-doped CeO_2(Ce_(1-x) Fe_xO_2, 0.01 ≤ x ≤ 0.07) nanospheres with diameters of 100~200 nm prepared by hydrothermal method using polyvinylpyrrolidone(PVP) as surfactant. The prepared samples were studied by using X-ray diffraction(XRD), Raman spectroscopy, transmission electron microscopy(TEM), high-resolution transmission electron microscopy(HRTEM), X-ray absorption near-edge structure(XANES), and vibrating sample magnetometry(VSM). The XRD results showed that Fe-doped CeO_2 was single-phased with a cubic structure, and with Fe^(3+)successfully substituting in Ce^(4+) sites. Raman spectra showed a redshift of F_(2g) mode that caused by the Fe doping. The samples of both undoped CeO_2 and Fe-doped CeO_2 exhibited room temperature ferromagnetism, and the saturated magnetization(Ms) increased with increasing Fe content until x = 0.05, and then the samples displayed ferromagnetic loops as well as paramagnetic behavior. The roles of Ce^(3+) and Fe^(3+)spin electrons are discussed for the ferromagnetism in the Fe-doped CeO_2.展开更多
Summary: To evaluate the feasibility of using polyethyleneimine (PEI) coated magnetic iron oxide nanoparticles (polyMAG-1000) as gene vectors. The surface characteristics of the nanoparticles were observed with scanni...Summary: To evaluate the feasibility of using polyethyleneimine (PEI) coated magnetic iron oxide nanoparticles (polyMAG-1000) as gene vectors. The surface characteristics of the nanoparticles were observed with scanning electron microscopy. The ability of the nanoparticles to combine with and protect DNA was investigated at different PH values after polyMAG-1000 and DNA were combined in different ratios. The nanoparticles were tested as gene vectors with in vitro transfection models. Under the scanning electron microscope the nanoparticles were about 100 nm in diameter. The nanoparticles could bind and condense DNA under acid, neutral and alkaline conditions, and they could transfer genes into cells and express green fluorescent proteins (GFP). The transfection efficiency was highest (51 %) when the ratio of nanoparticles to DNA was 1:1 (v:w). In that ratio, the difference in transfection efficiency was marked depending on whether a magnetic field was present or not: about 10 % when it was absent but 51 % when it was present. The magnetic iron oxide nanoparticles coated with PEI may potentially be used as gene vectors.展开更多
A great amount of red mud generated from alumina production by Bayer process was considered as a low-grade iron ore with a grade of 5wt% to 30wt% iron.We adopted the reduction roastingmagnetic separation process to re...A great amount of red mud generated from alumina production by Bayer process was considered as a low-grade iron ore with a grade of 5wt% to 30wt% iron.We adopted the reduction roastingmagnetic separation process to recover ferric oxide from red mud.The red mud samples were processed by reduction roasting,grinding and magnetic separating respectively.The effects of different parameters on the recovery rate of iron were studied in detail.The optimum techqicalparameters were proposed with 700 ℃roasting for 20 min,as 50wt% carbon and 4wt% additive were added.The experimentalresults indicated that the iron recovery and the grade of totaliron were 91% and 60%,respectively.A novelprocess is applicable to recover ferric oxide from the red mud waste fines.展开更多
Nd-doped In_2O_3 nanowires were fabricated by an Au-catalyzed chemical vapor deposition method.Nd atoms were successfully doped into the In_2O_3 host lattice structure,as revealed by energy dispersive x-ray spectrosco...Nd-doped In_2O_3 nanowires were fabricated by an Au-catalyzed chemical vapor deposition method.Nd atoms were successfully doped into the In_2O_3 host lattice structure,as revealed by energy dispersive x-ray spectroscopy,x-ray photoelectron spectroscopy,Raman spectroscopy,and x-ray diffraction.Robust room temperature ferromagnetism was observed in Nd-doped In_2O_3 nanowires,which was attributed to the long-range-mediated magnetization among Nd^(3+)-vacancy complexes through percolation-bound magnetic polarons.展开更多
The pre-treatment of zinc oxide bearing ores with high slime content is important to ensure that resources are utilized optimally. This paper reports an improved process using hydrocyclone de-sliming, dispersion reage...The pre-treatment of zinc oxide bearing ores with high slime content is important to ensure that resources are utilized optimally. This paper reports an improved process using hydrocyclone de-sliming, dispersion reagents, and magnetic removal of iron minerals for the pre-treatment of zinc oxide ore with a high slime and iron content, and the benefits compared to traditional technologies are shown. In addition, this paper investigates the damage related to fine slime and iron during zinc oxide flotation, the necessity of using hydrocyclone de-sliming together with dispersion reagents to alleviate the influence of slime, and interactions among hydrocyclone de-sliming, reagent dispersion, and magnetic iron removal. Results show that under optimized operating conditions the entire beneficiation technology results in a flotation concentrate with a Zn grade of 34.66% and a recovery of 73.41%.展开更多
The selected area electron diffraction (SAED) pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to...The selected area electron diffraction (SAED) pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to be different from either the pattern of pure Fe oxide nanoparticles or that of pure Au particles. Based on the fact that the ring diameters of these composite particles fit the characteristic relation for the fcc structure, the Au atoms on surfaces of the concerned particles are supposed to pack in a way more tightly than they usually do in pure Au nanoparticles. The driving force for this is the coherency strain which enables the shell material at the heterostructured interface to adapt the lattice parameters of the core.展开更多
Cux(Cu2O)1-x(0.09 x 1.00) granular films with thickness about 280 nm have been fabricated by direct current reactive magnetron sputtering. The atomic ratio x can be controlled by the oxygen flow rate during Cux(C...Cux(Cu2O)1-x(0.09 x 1.00) granular films with thickness about 280 nm have been fabricated by direct current reactive magnetron sputtering. The atomic ratio x can be controlled by the oxygen flow rate during Cux(Cu2O)1-x deposition. Room-temperature ferromagnetism(FM) is found in all of the samples. The saturated magnetization increases at first and then decreases with the decrease of x. The photoluminescence spectra show that the magnetization is closely correlated with the Cu vacancies in the Cux(Cu2O)1-x granular films. Fundamentally, the FM could be understood by the Stoner model based on the charge transfer mechanism. These results may provide solid evidence and physical insights on the origin of FM in the Cu2O-based oxides diluted magnetic semiconductors, especially for systems without intentional magnetic atom doping.展开更多
Superparamagnetic carbon-coated Fe3O4 nanoparticles with high magnetization(85 emu·g-(-1)) and high crystallinity were synthesized using polyethylene glycol-4000(PEG(4000)) as a carbon source.Fe3O4 water-...Superparamagnetic carbon-coated Fe3O4 nanoparticles with high magnetization(85 emu·g-(-1)) and high crystallinity were synthesized using polyethylene glycol-4000(PEG(4000)) as a carbon source.Fe3O4 water-based bilayer-surfactant-enveloped ferrofluids were subsequently prepared using sodium oleate and PEG(4000) as dispersants.Analyses using X-ray photoelectron spectroscopy,X-ray diffraction,and Fourier-transform infrared spectroscopy indicate that the Fe3O4 nanoparticles with a bilayer surfactant coating retain the inverse spinel-type structure and are successfully coated with sodium oleate and PEG(4000).Transmission electron microscopy,vibrating sample magnetometry,and particle-size analysis results indicate that the coated Fe3O4 nanoparticles also retain the good saturation magnetization of Fe3O4(79.6 emu·g^-1) and that the particle size of the bilayer-surfactant-enveloped Fe3O4 nanoparticles is 42.97 nm,which is substantially smaller than that of the unmodified Fe3O4 nanoparticles(486.2 nm).UV-vis and zeta-potential analyses reveal that the ferrofluids does not agglomerate for 120 h at a concentration of 4 g·L^-1,which indicates that the ferrofluids are highly stable.展开更多
Antibiotic contamination of the water environment has attracted much attention from researchers because of their potential hazards to humans and ecosystems.In this study,a multi-template molecularly imprinted polymer(...Antibiotic contamination of the water environment has attracted much attention from researchers because of their potential hazards to humans and ecosystems.In this study,a multi-template molecularly imprinted polymer(MIP)modified mesoporous silica coated magnetic graphene oxide(MGO@MS@MIP)was prepared by the surface imprinting method via a sol-gel process and was used for the selective,efficient and simultaneous removal of tetracyclines(TCs),including doxycycline(DC),tetracycline(TC),chlorotetracycline(CTC)and oxytetracycline(OTC)from water.The synthesized MIP composite was characterized by Fourier transform infrared spectroscopy,transmission electron microscope and thermogravimetric analysis.The adsorption properties of MGO@MS@MIP for these TCs were characterized through adsorption kinetics,isotherms and selectivity tests.The MIP composite revealed larger adsorption quantities,excellent selectivity and rapid kinetics for these four tetracyclines.The adsorption process was spontaneous and endothermic and followed the Freundlich isotherm model and the pseudo-second-order kinetic model.The MGO@MS@MIP could specifically recognize DC,TC,CTC and OTC in the presence of some chemical analogs.In addition,the sorption capacity of the MIP composite did not decrease significantly after repeated application for at least five cycles.Thus,the prepared magnetic MIP composite has great potential to contribute to the effective separation and removal of tetracyclines from water.展开更多
Microbial cells, either in free or immobilized form, can be used for the preconcentration or removal of metal ions, organic and inorganic xenobiotics or biologically active compounds. Magnetic modification of these ce...Microbial cells, either in free or immobilized form, can be used for the preconcentration or removal of metal ions, organic and inorganic xenobiotics or biologically active compounds. Magnetic modification of these cells enables to prepare magnetic adsorbents that can be easily manipulated in difficult-to-handle samples, such as suspensions, in the presence of external magnetic field. In this review, typical examples of magnetic modifications of microbial cells are presented, as well as their possible applications for the separation of organic xenobiotics and heavy metal ions.展开更多
Cadmium“Cd”is a toxic pollutant that may present in soil and water.This work evaluates:i)the use of non-steroidal anti-inflammatory drugs“NSAIDs”-bearing water for washing soil containing Cd(Ⅱ),ii)removal of Cd(...Cadmium“Cd”is a toxic pollutant that may present in soil and water.This work evaluates:i)the use of non-steroidal anti-inflammatory drugs“NSAIDs”-bearing water for washing soil containing Cd(Ⅱ),ii)removal of Cd(Ⅱ)from NSAID-bearing water by adsorption onto magnetic graphene oxide which can be easily separated by strong magnet.The studied NSAIDs are aspirin,ketoprofen,ibuprofern and diclofenac.The Cd(Ⅱ)-NSAIDs complexes were synthesized and characterized by FT-IR.Graphene was initially oxidized by either nitric acid,or ammonium persulphate method,or Hummer's method.Magnetite was then deposited on graphene oxide to give the corresponding magnetic graphene oxides(NA-MGO,APSMGO and Hum-MGO,respectively).The effect of the following factors on Cd(Ⅱ)uptake was investigated:NSAIDs type,pH,graphene oxidation method,magnetite:graphene oxide mass ratio in the adsorbent,(Cd(Ⅱ):NSAID)molar ratio.Maximum Cd(Ⅱ)uptake was achieved using“magnetic graphene oxidized with ammonium persulphate where the mass ratio of magnetite to graphene oxide was 2:1”in the presence of diclofenac at pH6.The best Cd(Ⅱ):diclofenac molar ratio was 1:3.The maximum adsorption capacity of Cd(Ⅱ)was found to be 83 mg L1.The regeneration of the adsorbent was possible by 0.3 M HNO3 solution and 80%of adsorption efficiency was maintained after five cycles.Upon presence of coexisting ions,80%of the adsorption efficiency was maintained.Various NSAIDs-containing waters were used for washing Cd-containing soil;the maximum removal efficiencies of Cd were 18%and 16%using 5 mM diclofenac or 10 mM aspirin,respectively.Using diclofenac or aspirin-spiked real pharmaceutical wastewater gave 28%removal of Cd.The optimum adsorption method was used for removal of Cd(Ⅱ)from diclofenac-containing soil-washing water,where two successive adsorptions were needed for complete Cd uptake.展开更多
This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite (Fe3O4) nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction....This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite (Fe3O4) nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction. The XRD results show that a weakly magnetic induction below 220 Gs could accelerate the phase transformation from goethite (α-FeOOH) to magnetite (Fe3O4), and affect the crystal structure, the particle size/morphology and magnetic response of the magnetite nano-particles synthesized. In addition, a higher concentration of the FeCl2 solution in the synthesis reaction led to finer particles, both with and without magnetic induction.展开更多
Fe_3O_4@SiO_2 magnetic nanoparticles functionalized with mesoporous cerium oxide(Fe_3O_4@SiO_2@mCeO_2) was fabricated as a novel adsorbent to remove phosphate from water. The prepared adsorbent was characterized by ...Fe_3O_4@SiO_2 magnetic nanoparticles functionalized with mesoporous cerium oxide(Fe_3O_4@SiO_2@mCeO_2) was fabricated as a novel adsorbent to remove phosphate from water. The prepared adsorbent was characterized by X-ray diffractometry(XRD), transmission electron microscopy(TEM), nitrogen adsorption-desorption and vibrating sample magnetometry(VSM), and its phosphate removal performance was investigated through the batch adsorption studies. Characterization results confirmed that mesoporous cerium oxide was successfully assembled on the surface of Fe_3O_4@SiO_2 nanoparticles, and the synthesized adsorbent possessed a typical core-shell structure with a BET surface area of 195 m^2/g, accessible mesopores of 2.6 nm, and the saturation magnetization of 21.11 emu/g. The newly developed adsorbent had an excellent performance in adsorbing phosphate, and its maximum adsorption capacity calculated from the Langmuir model was 64.07 mg/g. The adsorption was fast, and the kinetic data could be best fitted with the pseudo-second-order kinetic model. The phosphate removal decreased with the increase of solution pH(2 to 10), while the higher ionic strength slightly promoted the phosphate adsorption. The presence of Cl~– and SO^(2–)_4 could enhance the adsorption of phosphate whereas HCO~–_ 3 had interfering effect on the phosphate adsorption. The adsorption mechanism was studied by analyzing Zeta potential and FTIR spectroscopy, and the results indicated that the replacement of the surface hydroxyl groups by phosphate ions with the formation of inner-sphere complex played a key role in the phosphate adsorption. The spent adsorbent could be quickly separated from aqueous solution with the assistance of the external magnetic field, and the adsorbed phosphate could be effectively desorbed using a 1 mol/L NaOH solution.展开更多
A novel magnetically recoverable thioporphyrazine catalyst(CoPz(S-Bu)8/SiO2@Fe3O4) was prepared by immobilization of the cobalt octkis(butylthio) porphyrazine complex(CoPz(S-Bu)8) on silica-coated magnetic n...A novel magnetically recoverable thioporphyrazine catalyst(CoPz(S-Bu)8/SiO2@Fe3O4) was prepared by immobilization of the cobalt octkis(butylthio) porphyrazine complex(CoPz(S-Bu)8) on silica-coated magnetic nanospheres(SiO2@Fe3O4). The composite CoPz(S-Bu)8/SiO2@Fe3O4appeared to be an active catalyst in the oxidation of benzyl alcohol in aqueous solution using hydrogen peroxide(H2O2) as oxidant under Xe-lamp irradiation,with 36.4% conversion of benzyl alcohol, about 99% selectivity for benzoic acid and turnover number(TON) of 61.7 at ambient temperature. The biomimetic catalyst CoPz(S-Bu)8was supported on the magnetic carrier SiO2@Fe3O4 so as to suspend it in aqueous solution to react with substrates, utilizing its lipophilicity. Meanwhile the CoPz(S-Bu)8can use its unique advantages to control the selectivity of photocatalytic oxidation without the substrate being subjected to deep oxidation. The influence of various reaction parameters on the conversion rate of benzyl alcohol and selectivity of benzoic acid was investigated in detail. Moreover, photocatalytic oxidation of substituted benzyl alcohols was obtained with high conversion and excellent selectivity, specifically conversion close to 70%, selectivity close to 100% and TON of 113.6 for para-position electron-donating groups. The selectivity and eco-friendliness of the biomimetic photocatalyst give it great potential for practical applications.展开更多
Magnetically separable CuO nanoparticles supported on graphene oxide(Fe3O4 NPs/GO-CuO NPs) is synthesized and characterized for the preparation of propargylamines in EtOH,at 90 C.Fe3O4 NPs/GOCuO NPs is found to be a...Magnetically separable CuO nanoparticles supported on graphene oxide(Fe3O4 NPs/GO-CuO NPs) is synthesized and characterized for the preparation of propargylamines in EtOH,at 90 C.Fe3O4 NPs/GOCuO NPs is found to be an efficient catalyst for the A^3-coupling of aldehydes,amines,and alkynes through C-H activation.Both aromatic and aliphatic aldehydes and alkynes are combined with secondary amines to provide a wide range of propargylamines in moderate to excellent yields.展开更多
In this study,we prepared mitochondrion targeting peptide-grafted magnetic graphene oxide(GO)nanocarriers for efficient impairment of the tumor mitochondria.The two-dimensional GOMNP-MitP nanosheets were synthesized b...In this study,we prepared mitochondrion targeting peptide-grafted magnetic graphene oxide(GO)nanocarriers for efficient impairment of the tumor mitochondria.The two-dimensional GOMNP-MitP nanosheets were synthesized by grafting magnetic y-Fe_(2)O_(3)to the surface of GO,followed by covalent modification of mitochondrion targeting peptide(MitP).GOMNP-MitP exhibited the high capacity of loading the anticancer drug mitoxantrone(MTX),and preferentially targeted the tumor mitochondria.With the aid of alternating magnetic field(AMF),the MTX-loading GOMNP-MitP released MTX to the mitochondria,severely impairing mitochondrial functions,including attenuation of ATP production,decrease in mitochondrial membrane potential(MMP),and further leading to activation of apoptosis.This study realized high-efficient mitochondrion-ta rgeting drug delivery for anticancer therapy by twodimensional nanoplatforms.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 50931002, 51072094 and 51372135)the Ministry of Education of the People’s Republic of China(Grant No. 113007A)the Tsinghua University Initiative Scientific Research Program
文摘In the past several decades, dilute magnetic semiconductors, particularly the dilute magnetic oxides have evolved into an important branch of materials science due to their potential application in spintronic devices combining of properties of semiconductors and ferromagnets. In spite of a major effort devoted to the mechanism of ferromagnetism with a high Curie temperature in these materials, it still remains the most controversial research topic, especially given the unexpected do ferromagnetism in a series of undoped wide-band-gap oxides films or nanostructures. Recently, an abundance of research has shown the critical role of various defects in the origin and control of spontaneous magnetic ordering, but contradicting views from intertwined theoretical calculations and experiments require more in-depth systematic research. In our previous work, considerable efforts have been focused on two major oxides, i.e. ZnO and Zr02. This review will present a summary of current experimental status of this defect-driven ferromag- netism in dilute magnetic oxides (DMOs).
基金supported by the Research and Development Institute at Nakhon Si Thammarat Rajabhat University and the Nanomaterials Chemistry Research Unit at Nakhon Si Thammarat Rajabhat University,Nakhon Si Thammarat,Thailand(Grant No.004/2563).
文摘In this paper, we present a proof-of-concept study of the enhancement of photocatalytic activity via a combined strategy of fabricating a visible-light responsive ternary heterostructure and improving overall photostability by incorporating magnetic zinc oxide/graphene/iron oxide (ZGF). A solvothermal approach was used to synthesize the catalyst. X-ray diffraction (XRD), scanning electron microscopic, energy dispersive X-ray, transmission electron microscopic, vibrating sample magnetometric, and ultraviolet–visible diffuse reflectance spectroscopic techniques were used to characterize the synthesized samples. The obtained optimal Zn(NO_(3))_(2) concentration, temperature, and heating duration were 0.10 mol/L, 600℃, and 1 h, respectively. The XRD pattern revealed the presence of peaks corresponding to zinc oxide, graphene, and iron oxide, indicating that the ZGF catalyst was effectively synthesized. Furthermore, when the developed ZGF was used for methylene blue dye degradation, the optimum irradiation time, dye concentration, catalyst dosage, irradiation intensity, and solution pH were 90 min, 10 mg/L, 0.03 g/L, 100 W, and 8.0, respectively. Therefore, the synthesized ZGF system could be used as a catalyst to degrade dyes in wastewater samples. This hybrid nanocomposite consisting of zinc oxide, graphene, and iron oxide could also be used as an effective photocatalytic degrader for various dye pollutants.
基金Project supported by the National Key Research Program of China(Grant Nos.2018YFF01010303,2017YFB0702702,and 2016YFA0300701)the National Natural Sciences Foundation of China(Grant Nos.52031015,1187411,51427801,and 51871235)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant Nos.QYZDJ-SSW-JSC023,KJZD-SW-M01,and ZDYZ2012-2).
文摘We investigate the ultrafast spin dynamics of an antiferromagnet in a ferromagnet/antiferromagnet heterostructure Fe/GdFeO_(3) via an all-optical method.After laser irradiation,the terahertz spin precession is hard to be excited in a bare GdFeO_(3) without spin reorientation phase but efficiently in Fe/GdFeO_(3).Both quasi-ferromagnetic and impurity modes,as well as a phonon mode,are observed.We attribute it to the optical modification of interfacial exchange coupling between Fe and GdFeO3.Moreover,the excitation efficiency of dynamics can be modified significantly via the pump laser influence.Our results elucidate that the interfacial exchange coupling is a feasible stimulation to efficiently excite terahertz spin dynamics in antiferromagnets.It will expand the exploration of terahertz spin dynamics for antiferromagnet-based opto-spintronic devices.
文摘This paper obtains the room temperature ferromagnetism in Sn1-x FexO2 films fabricated by the Sol-Gel method. X-ray diffraction results show that Fe doping inhibits the growth of SnO2 and Fe^3+ ions occupy the Sn sites. The measurement of resistance excludes the free carrier inducing ferromagnetism. Moreover, the temperature dependence of magnetization has been better fitted by the Curie Weiss law and bound magnetic polaron (BMP) theory. An enhancement of ferromagnetism is achieved by annealing the samples with x = 7.1% in H2, and a decrease of oxygen flow rate. All these results prove that the BMP model depending on defects can explain ferromagnetism in diluted magnetic oxides.
基金the Thailand Research Fund through the Royal Golden Jubilee Ph.D.program (Grant No. PHD/0275/2550)supported by Suranaree University of Technology (SUT)the Office of the Higher Education Commission under NRU project of Thailand
文摘This work reports the study concerning the structure and magnetic properties of undoped CeO_2 and Fe-doped CeO_2(Ce_(1-x) Fe_xO_2, 0.01 ≤ x ≤ 0.07) nanospheres with diameters of 100~200 nm prepared by hydrothermal method using polyvinylpyrrolidone(PVP) as surfactant. The prepared samples were studied by using X-ray diffraction(XRD), Raman spectroscopy, transmission electron microscopy(TEM), high-resolution transmission electron microscopy(HRTEM), X-ray absorption near-edge structure(XANES), and vibrating sample magnetometry(VSM). The XRD results showed that Fe-doped CeO_2 was single-phased with a cubic structure, and with Fe^(3+)successfully substituting in Ce^(4+) sites. Raman spectra showed a redshift of F_(2g) mode that caused by the Fe doping. The samples of both undoped CeO_2 and Fe-doped CeO_2 exhibited room temperature ferromagnetism, and the saturated magnetization(Ms) increased with increasing Fe content until x = 0.05, and then the samples displayed ferromagnetic loops as well as paramagnetic behavior. The roles of Ce^(3+) and Fe^(3+)spin electrons are discussed for the ferromagnetism in the Fe-doped CeO_2.
文摘Summary: To evaluate the feasibility of using polyethyleneimine (PEI) coated magnetic iron oxide nanoparticles (polyMAG-1000) as gene vectors. The surface characteristics of the nanoparticles were observed with scanning electron microscopy. The ability of the nanoparticles to combine with and protect DNA was investigated at different PH values after polyMAG-1000 and DNA were combined in different ratios. The nanoparticles were tested as gene vectors with in vitro transfection models. Under the scanning electron microscope the nanoparticles were about 100 nm in diameter. The nanoparticles could bind and condense DNA under acid, neutral and alkaline conditions, and they could transfer genes into cells and express green fluorescent proteins (GFP). The transfection efficiency was highest (51 %) when the ratio of nanoparticles to DNA was 1:1 (v:w). In that ratio, the difference in transfection efficiency was marked depending on whether a magnetic field was present or not: about 10 % when it was absent but 51 % when it was present. The magnetic iron oxide nanoparticles coated with PEI may potentially be used as gene vectors.
基金Funded by the Fundamental Research Funds for the Central Universities(No.310827151063)the Provincial Training Program of Innovation and Entrepreneurship for Undergraduates(No.201510710134)
文摘A great amount of red mud generated from alumina production by Bayer process was considered as a low-grade iron ore with a grade of 5wt% to 30wt% iron.We adopted the reduction roastingmagnetic separation process to recover ferric oxide from red mud.The red mud samples were processed by reduction roasting,grinding and magnetic separating respectively.The effects of different parameters on the recovery rate of iron were studied in detail.The optimum techqicalparameters were proposed with 700 ℃roasting for 20 min,as 50wt% carbon and 4wt% additive were added.The experimentalresults indicated that the iron recovery and the grade of totaliron were 91% and 60%,respectively.A novelprocess is applicable to recover ferric oxide from the red mud waste fines.
基金Project supported by the National Natural Science Foundation of China(Grant No.11274003)the Priority Academic Program Development of Jiangsu Higher Education Institutions,Chinathe Fundamental Research Funds for the Central Universities,China
文摘Nd-doped In_2O_3 nanowires were fabricated by an Au-catalyzed chemical vapor deposition method.Nd atoms were successfully doped into the In_2O_3 host lattice structure,as revealed by energy dispersive x-ray spectroscopy,x-ray photoelectron spectroscopy,Raman spectroscopy,and x-ray diffraction.Robust room temperature ferromagnetism was observed in Nd-doped In_2O_3 nanowires,which was attributed to the long-range-mediated magnetization among Nd^(3+)-vacancy complexes through percolation-bound magnetic polarons.
基金financially supported by the Natural Science Foundation of Hubei Province,China(No.2014CFB794)the Young Fund of Wuhan Institute of Technology(No.Q201405)the Natural Science Foundation of Hunan Province for International Cooperation and Innovation(Nos.2017JJ4035 and 2016WK2049)
文摘The pre-treatment of zinc oxide bearing ores with high slime content is important to ensure that resources are utilized optimally. This paper reports an improved process using hydrocyclone de-sliming, dispersion reagents, and magnetic removal of iron minerals for the pre-treatment of zinc oxide ore with a high slime and iron content, and the benefits compared to traditional technologies are shown. In addition, this paper investigates the damage related to fine slime and iron during zinc oxide flotation, the necessity of using hydrocyclone de-sliming together with dispersion reagents to alleviate the influence of slime, and interactions among hydrocyclone de-sliming, reagent dispersion, and magnetic iron removal. Results show that under optimized operating conditions the entire beneficiation technology results in a flotation concentrate with a Zn grade of 34.66% and a recovery of 73.41%.
文摘The selected area electron diffraction (SAED) pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to be different from either the pattern of pure Fe oxide nanoparticles or that of pure Au particles. Based on the fact that the ring diameters of these composite particles fit the characteristic relation for the fcc structure, the Au atoms on surfaces of the concerned particles are supposed to pack in a way more tightly than they usually do in pure Au nanoparticles. The driving force for this is the coherency strain which enables the shell material at the heterostructured interface to adapt the lattice parameters of the core.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11104148,51101088,and 51171082)the Tianjin Natural Science Foundation,China(Grant Nos.14JCZDJC37700 and 13JCQNJC02800)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20110031110034)the Fundamental Research Funds for the Central Universities,China
文摘Cux(Cu2O)1-x(0.09 x 1.00) granular films with thickness about 280 nm have been fabricated by direct current reactive magnetron sputtering. The atomic ratio x can be controlled by the oxygen flow rate during Cux(Cu2O)1-x deposition. Room-temperature ferromagnetism(FM) is found in all of the samples. The saturated magnetization increases at first and then decreases with the decrease of x. The photoluminescence spectra show that the magnetization is closely correlated with the Cu vacancies in the Cux(Cu2O)1-x granular films. Fundamentally, the FM could be understood by the Stoner model based on the charge transfer mechanism. These results may provide solid evidence and physical insights on the origin of FM in the Cu2O-based oxides diluted magnetic semiconductors, especially for systems without intentional magnetic atom doping.
基金supported by the National Natural Science Foundation of China (No.51063003)the Ministry of Science and Technology Project (No.2009GJG10041)the Fundamental Research Funds for the Universities of Gansu (No.1105ZTC136)
文摘Superparamagnetic carbon-coated Fe3O4 nanoparticles with high magnetization(85 emu·g-(-1)) and high crystallinity were synthesized using polyethylene glycol-4000(PEG(4000)) as a carbon source.Fe3O4 water-based bilayer-surfactant-enveloped ferrofluids were subsequently prepared using sodium oleate and PEG(4000) as dispersants.Analyses using X-ray photoelectron spectroscopy,X-ray diffraction,and Fourier-transform infrared spectroscopy indicate that the Fe3O4 nanoparticles with a bilayer surfactant coating retain the inverse spinel-type structure and are successfully coated with sodium oleate and PEG(4000).Transmission electron microscopy,vibrating sample magnetometry,and particle-size analysis results indicate that the coated Fe3O4 nanoparticles also retain the good saturation magnetization of Fe3O4(79.6 emu·g^-1) and that the particle size of the bilayer-surfactant-enveloped Fe3O4 nanoparticles is 42.97 nm,which is substantially smaller than that of the unmodified Fe3O4 nanoparticles(486.2 nm).UV-vis and zeta-potential analyses reveal that the ferrofluids does not agglomerate for 120 h at a concentration of 4 g·L^-1,which indicates that the ferrofluids are highly stable.
基金the Science and Technology Planning Project of Guangzhou,China(No.201803030040)the National Natural Science Foundation of China(Grant No.41272262)the Major Projects(Natural Science)of Education Department of Guangdong Province,China(261555101).
文摘Antibiotic contamination of the water environment has attracted much attention from researchers because of their potential hazards to humans and ecosystems.In this study,a multi-template molecularly imprinted polymer(MIP)modified mesoporous silica coated magnetic graphene oxide(MGO@MS@MIP)was prepared by the surface imprinting method via a sol-gel process and was used for the selective,efficient and simultaneous removal of tetracyclines(TCs),including doxycycline(DC),tetracycline(TC),chlorotetracycline(CTC)and oxytetracycline(OTC)from water.The synthesized MIP composite was characterized by Fourier transform infrared spectroscopy,transmission electron microscope and thermogravimetric analysis.The adsorption properties of MGO@MS@MIP for these TCs were characterized through adsorption kinetics,isotherms and selectivity tests.The MIP composite revealed larger adsorption quantities,excellent selectivity and rapid kinetics for these four tetracyclines.The adsorption process was spontaneous and endothermic and followed the Freundlich isotherm model and the pseudo-second-order kinetic model.The MGO@MS@MIP could specifically recognize DC,TC,CTC and OTC in the presence of some chemical analogs.In addition,the sorption capacity of the MIP composite did not decrease significantly after repeated application for at least five cycles.Thus,the prepared magnetic MIP composite has great potential to contribute to the effective separation and removal of tetracyclines from water.
文摘Microbial cells, either in free or immobilized form, can be used for the preconcentration or removal of metal ions, organic and inorganic xenobiotics or biologically active compounds. Magnetic modification of these cells enables to prepare magnetic adsorbents that can be easily manipulated in difficult-to-handle samples, such as suspensions, in the presence of external magnetic field. In this review, typical examples of magnetic modifications of microbial cells are presented, as well as their possible applications for the separation of organic xenobiotics and heavy metal ions.
文摘Cadmium“Cd”is a toxic pollutant that may present in soil and water.This work evaluates:i)the use of non-steroidal anti-inflammatory drugs“NSAIDs”-bearing water for washing soil containing Cd(Ⅱ),ii)removal of Cd(Ⅱ)from NSAID-bearing water by adsorption onto magnetic graphene oxide which can be easily separated by strong magnet.The studied NSAIDs are aspirin,ketoprofen,ibuprofern and diclofenac.The Cd(Ⅱ)-NSAIDs complexes were synthesized and characterized by FT-IR.Graphene was initially oxidized by either nitric acid,or ammonium persulphate method,or Hummer's method.Magnetite was then deposited on graphene oxide to give the corresponding magnetic graphene oxides(NA-MGO,APSMGO and Hum-MGO,respectively).The effect of the following factors on Cd(Ⅱ)uptake was investigated:NSAIDs type,pH,graphene oxidation method,magnetite:graphene oxide mass ratio in the adsorbent,(Cd(Ⅱ):NSAID)molar ratio.Maximum Cd(Ⅱ)uptake was achieved using“magnetic graphene oxidized with ammonium persulphate where the mass ratio of magnetite to graphene oxide was 2:1”in the presence of diclofenac at pH6.The best Cd(Ⅱ):diclofenac molar ratio was 1:3.The maximum adsorption capacity of Cd(Ⅱ)was found to be 83 mg L1.The regeneration of the adsorbent was possible by 0.3 M HNO3 solution and 80%of adsorption efficiency was maintained after five cycles.Upon presence of coexisting ions,80%of the adsorption efficiency was maintained.Various NSAIDs-containing waters were used for washing Cd-containing soil;the maximum removal efficiencies of Cd were 18%and 16%using 5 mM diclofenac or 10 mM aspirin,respectively.Using diclofenac or aspirin-spiked real pharmaceutical wastewater gave 28%removal of Cd.The optimum adsorption method was used for removal of Cd(Ⅱ)from diclofenac-containing soil-washing water,where two successive adsorptions were needed for complete Cd uptake.
文摘This paper presents experimental results on weakly magnetic field-assisted synthesis of magnetite (Fe3O4) nano-particles in an oxidative co-precipitation method, in comparison to the case without magnetic induction. The XRD results show that a weakly magnetic induction below 220 Gs could accelerate the phase transformation from goethite (α-FeOOH) to magnetite (Fe3O4), and affect the crystal structure, the particle size/morphology and magnetic response of the magnetite nano-particles synthesized. In addition, a higher concentration of the FeCl2 solution in the synthesis reaction led to finer particles, both with and without magnetic induction.
基金supported by Natural Science Foundation of China(21706178)"utilization of low rank coal"Strategic Leading Special Fund,Strategic Leading Special Fund of CAS(XDA-07070800,XDA-07070400)the Opening Foundation of State Key Laboratory of Coal Conversion(J16-17-602)
文摘Fe_3O_4@SiO_2 magnetic nanoparticles functionalized with mesoporous cerium oxide(Fe_3O_4@SiO_2@mCeO_2) was fabricated as a novel adsorbent to remove phosphate from water. The prepared adsorbent was characterized by X-ray diffractometry(XRD), transmission electron microscopy(TEM), nitrogen adsorption-desorption and vibrating sample magnetometry(VSM), and its phosphate removal performance was investigated through the batch adsorption studies. Characterization results confirmed that mesoporous cerium oxide was successfully assembled on the surface of Fe_3O_4@SiO_2 nanoparticles, and the synthesized adsorbent possessed a typical core-shell structure with a BET surface area of 195 m^2/g, accessible mesopores of 2.6 nm, and the saturation magnetization of 21.11 emu/g. The newly developed adsorbent had an excellent performance in adsorbing phosphate, and its maximum adsorption capacity calculated from the Langmuir model was 64.07 mg/g. The adsorption was fast, and the kinetic data could be best fitted with the pseudo-second-order kinetic model. The phosphate removal decreased with the increase of solution pH(2 to 10), while the higher ionic strength slightly promoted the phosphate adsorption. The presence of Cl~– and SO^(2–)_4 could enhance the adsorption of phosphate whereas HCO~–_ 3 had interfering effect on the phosphate adsorption. The adsorption mechanism was studied by analyzing Zeta potential and FTIR spectroscopy, and the results indicated that the replacement of the surface hydroxyl groups by phosphate ions with the formation of inner-sphere complex played a key role in the phosphate adsorption. The spent adsorbent could be quickly separated from aqueous solution with the assistance of the external magnetic field, and the adsorbed phosphate could be effectively desorbed using a 1 mol/L NaOH solution.
基金supported by the National Natural Science Foundation of China (Nos. 21272281 and 20977115)Natural Science Foundation of Hubei Province (2014CFB919)+1 种基金"the Fundamental Research Funds for the Central Universities", South-Central University for Nationalities (CZY14003)the Science and Technology Plan Innovation Team of Wuhan City (2015070504020220)
文摘A novel magnetically recoverable thioporphyrazine catalyst(CoPz(S-Bu)8/SiO2@Fe3O4) was prepared by immobilization of the cobalt octkis(butylthio) porphyrazine complex(CoPz(S-Bu)8) on silica-coated magnetic nanospheres(SiO2@Fe3O4). The composite CoPz(S-Bu)8/SiO2@Fe3O4appeared to be an active catalyst in the oxidation of benzyl alcohol in aqueous solution using hydrogen peroxide(H2O2) as oxidant under Xe-lamp irradiation,with 36.4% conversion of benzyl alcohol, about 99% selectivity for benzoic acid and turnover number(TON) of 61.7 at ambient temperature. The biomimetic catalyst CoPz(S-Bu)8was supported on the magnetic carrier SiO2@Fe3O4 so as to suspend it in aqueous solution to react with substrates, utilizing its lipophilicity. Meanwhile the CoPz(S-Bu)8can use its unique advantages to control the selectivity of photocatalytic oxidation without the substrate being subjected to deep oxidation. The influence of various reaction parameters on the conversion rate of benzyl alcohol and selectivity of benzoic acid was investigated in detail. Moreover, photocatalytic oxidation of substituted benzyl alcohols was obtained with high conversion and excellent selectivity, specifically conversion close to 70%, selectivity close to 100% and TON of 113.6 for para-position electron-donating groups. The selectivity and eco-friendliness of the biomimetic photocatalyst give it great potential for practical applications.
文摘Magnetically separable CuO nanoparticles supported on graphene oxide(Fe3O4 NPs/GO-CuO NPs) is synthesized and characterized for the preparation of propargylamines in EtOH,at 90 C.Fe3O4 NPs/GOCuO NPs is found to be an efficient catalyst for the A^3-coupling of aldehydes,amines,and alkynes through C-H activation.Both aromatic and aliphatic aldehydes and alkynes are combined with secondary amines to provide a wide range of propargylamines in moderate to excellent yields.
基金supported by National Natural Science Foundation of China(No.31870139)Natural Science Foundation of Tianjin(No.19JCZDJC33800)+1 种基金Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(No.TSBICIP-KJGG-006)the Fundamental Research for the Central Universities。
文摘In this study,we prepared mitochondrion targeting peptide-grafted magnetic graphene oxide(GO)nanocarriers for efficient impairment of the tumor mitochondria.The two-dimensional GOMNP-MitP nanosheets were synthesized by grafting magnetic y-Fe_(2)O_(3)to the surface of GO,followed by covalent modification of mitochondrion targeting peptide(MitP).GOMNP-MitP exhibited the high capacity of loading the anticancer drug mitoxantrone(MTX),and preferentially targeted the tumor mitochondria.With the aid of alternating magnetic field(AMF),the MTX-loading GOMNP-MitP released MTX to the mitochondria,severely impairing mitochondrial functions,including attenuation of ATP production,decrease in mitochondrial membrane potential(MMP),and further leading to activation of apoptosis.This study realized high-efficient mitochondrion-ta rgeting drug delivery for anticancer therapy by twodimensional nanoplatforms.