Ultrasmall superparamagnetic iron oxide nanoparticles(usSPIONs)are promising alternatives to gadolinium‐based contrast agents for positive contrast enhancement in magnetic resonance imaging(MRI).Unlike larger SPIONs ...Ultrasmall superparamagnetic iron oxide nanoparticles(usSPIONs)are promising alternatives to gadolinium‐based contrast agents for positive contrast enhancement in magnetic resonance imaging(MRI).Unlike larger SPIONs that primarily function as T2/T2*negative contrast agents,usSPIONs with core diameters below 5 nm can effectively shorten T1 relaxation times,producing bright signals in T1‐weighted images.This distinct behavior stems from their unique magnetic properties,including single‐domain configurations,surface spin canting,and rapid Néel relaxation dynamics,which are particularly enhanced at low magnetic field strengths.The biocompatibility of iron oxide,efficient renal clearance pathways,and versatility for surface functionalization offer potential advantages over gadolinium‐based agents,especially regarding safety concerns related to nephrogenic systemic fibrosis and gadolinium deposition.These nanoparticles show particular promise for applications in lowfield MRI,vascular imaging,targeted molecular imaging,and theranostic platforms.Although challenges remain in optimizing synthesis methods for consistent production of monodisperse usSPIONs with tailored surface chemistry,ongoing research continues to advance their potential for clinical translation.This review explores the mechanisms,synthesis approaches,applications,and future perspectives of usSPIONs as positive contrast agents in MRI.展开更多
Both soil organic carbon (SOC) and iron (Fe) oxide content, among other factors, drive the formation and stability of soil aggregates.However, the mechanism of these drivers in greenhouse soil fertilized with organic ...Both soil organic carbon (SOC) and iron (Fe) oxide content, among other factors, drive the formation and stability of soil aggregates.However, the mechanism of these drivers in greenhouse soil fertilized with organic fertilizer is not well understood.In a 3-year field experiment, we aimed to investigate the factors which drive the stability of soil aggregates in greenhouse soil.To explore the impact of organic fertilizer on soil aggregates, we established four treatments:no fertilization (CK);inorganic fertilizer (CF);organic fertilizer (OF);and combined application of inorganic and organic fertilizers(COF).The application of organic fertilizer significantly enhanced the stability of aggregates, that is it enhanced the mean weight diameter, geometric mean diameter and aggregate content (%) of>0.25 mm aggregate fractions.OF and COF treatments increased the concentration of SOC, especially the aliphatic-C, aromatic-C and polysaccharide-C components of SOC, particularly in>0.25 mm aggregates.Organic fertilizer application significantly increased the content of free Fe(Fed), reactive Fe (Feo), and non-crystalline Fe in both bulk soil and aggregates.Furthermore, non-crystalline Fe showed a positive correlation with SOC content in both bulk soil and aggregates.Both non-crystalline Fe and SOC were significantly positively correlated with>2 mm mean weight diameter.Overall, we believe that the increase of SOC, aromatic-C, and non-crystal ine Fe concentrations in soil after the application of organic fertilizer is the reason for improving soil aggregate stability.展开更多
The efficiency and mechanism of hydrous iron oxide(HFO)and HFO/calcite mixture to inactivate the phosphorus in the overlying water(OW)/sediment system under the feed adding condition were explored,and the effect of HF...The efficiency and mechanism of hydrous iron oxide(HFO)and HFO/calcite mixture to inactivate the phosphorus in the overlying water(OW)/sediment system under the feed adding condition were explored,and the effect of HFO and HFO/calcite mixture addition on the diversity,composition and function of bacterial communities in the sediment was examined.HFO and HFO/calcite mixture direct addition can effectively lower the concentration of soluble reactive phosphorus(RSP)and diffusion gradient in thin film-unstable phosphorus(PD GT)in OW and inactivate the P DGTin the upper sediment.The elimination efficiencies of RSP by the direct HFO and HFO/calcite mixture addition were 48.9%-97.0%and 42.4%-95.4%,respectively.The alteration in the addition mode from the one-time to multiple direct addition was beneficial to the immobilization of RSP and PD GTin OW and P DGTin the upper sediment by HFO and HFO/calcite mixture under the feed input condition in the long run.Permeable fabric wrapping reduced the inactivation efficiency of RSP in OW by HFO and HFO/calcite mixture,but it made the recycling of these materials possible.Most of P immobilized by HFO and HFO/calcite mixture was relatively or very stable.After the HFO and HFO/calcite mixture addition,the composition of bacterial communities in the surface sediment changed.However,the bacterial communities in the amended sediments still can perform good ecological function.Our findings suggest that HFO and HFO/calcite mixture are promising phosphorus-immobilization materials for the inactivation of RSP and PD GTin OW and PD GTin the upper sediment under the feed inputting condition.展开更多
Magnetic iron oxide nanoparticles(Fe_(x)O_(y) NPs,mainly Fe3O4 andγ-Fe2O_(3))are nanomaterials ubiquitously present in aquatic,terrestrial,and atmospheric environments,with a high prevalence and complex sources.Over ...Magnetic iron oxide nanoparticles(Fe_(x)O_(y) NPs,mainly Fe3O4 andγ-Fe2O_(3))are nanomaterials ubiquitously present in aquatic,terrestrial,and atmospheric environments,with a high prevalence and complex sources.Over the past decade,numerous reports have emerged on the presence of exogenous particles in human body,facilitated by the rapid development of separation and detection methods.The health risk associated with magnetic Fe_(x)O_(y) NP have garnered escalating attention due to their presence in human blood and brain tissues,especially for their potential association with neurodegenerative diseases like Alzheimer’s disease.In this paper,we provide a comprehensive overview of sources,analysis methods,environmental impacts,and health risks of magnetic Fe_(x)O_(y) NP.Currently,most researches are primarily based on engineered Fe_(x)O_(y) NP,while reports aboutmagnetic Fe_(x)O_(y) NP existing in real-world environments are still limited,especially for their occurrence levels in various environmental matrices,environmental transformation behavior,and biotoxic effects.Our study reviews this emerging pollutant,providing insights to address current research deficiencies and chart the course for future studies.展开更多
Iron oxide nanoparticles(IONPs)with intrinsic peroxidase(POD)-mimic activity have gained significant attention as nanozymes.Reducing sizes of IONPs is the mostly applied strategy to boost their enzymatic activity due ...Iron oxide nanoparticles(IONPs)with intrinsic peroxidase(POD)-mimic activity have gained significant attention as nanozymes.Reducing sizes of IONPs is the mostly applied strategy to boost their enzymatic activity due to their high specific surface areas.Herein,we synthesized a series of uniformly sized IONPs ranging from3.17 to 21.2 nm,and found that POD activity of IONPs is not monotone increased by reducing their sizes,with the optimal size of 7.82 nm rather than smaller sized 3.17 nm.The reason for this unnormal phenomenon is that electronic structure also had great influence on POD activity,especially at the ultrasmall size region.Since Fe^(2+)are with higher enzymatic activity than Fe^(3+),3.17 nm IONPs although have the largest specific surface area,are prone to be oxidized,which reduced their iron content and ratio of Fe^(2+)to Fe^(3+),and consequently decreased their POD activity.By intentionally oxidized 7.82 nm IONPs in air,POD activity was obviously reduced,illustrating electronic structure cannot be overlooked.At the larger sized region ranging from 7.82 to 21.2 nm,oxidation degree of IONPs is similar,and surface electronic structure had a negligible effect on POD activity,and therefore,POD activity is predominantly influenced by specific surface area.By using the optimized 7.82 nm IONPs,tumor growth was obviously inhibited,demonstrating their potential in cancer therapeutics.Our results reveal that the designing of nanozymes should comprehensively balance their influence of surface electronic structure and specific surface area.展开更多
Early diagnosis and accurate boundary delineation are the key steps of tumor precision medicine.Circulating tumor cells(CTCs)detection of liquid biopsy can provide abundant information for early diagnosis of cancer.Hi...Early diagnosis and accurate boundary delineation are the key steps of tumor precision medicine.Circulating tumor cells(CTCs)detection of liquid biopsy can provide abundant information for early diagnosis of cancer.High detection specificity and good enrichment features are two key factors for CTCs accurate identification in peripheral blood sample.For this purpose,iron oxide(IO)-based surface-enhanced Raman scattering(SERS)bioprobes with good biocompatibility,high detection sensitivity,remarkable detection specificity,and good enrichment efficiency,were developed for detecting different types of CTCs.Magnetic SERS bioprobes combined with programmed death ligand-1(PD-L1)antibody are regarded as an effective way to boost the targeting ability and detection specificity,benefiting for accurately capturing and identifying rare CTCs.Four types of CTCs with different PD-L1 expression were accurately distinguished among white blood cells via high-resolution SERS mapping images and stable Raman signals.Subsequently,CTCs blood samples obtained from the triple negative breast cancer patients were also successfully recognized compared to that of health people,indicating IO@AR@PDA-a PD-L1 SERS bioprobe possessed great potential for CTCs detection in liquid biopsy.Additionally,IO-based bioprobe exhibited excellent dual-modal imaging abilities of high-resolution SERS imaging mode and microimaging magnetic resonance imaging mode.These two highly complementary imaging modes endowed IO-based bioprobes unrivalled capacity in tumor boundary differentiation,supporting tumor accurate resection and precise surgery.To our best knowledge,this is the first time that biocompatible IO-based SERS bioprobes without noble metal element were reported not only for CTCs accurate detection,but also for precise tumor boundary delineation,showing great advantages in tumor diagnosis and treatment.展开更多
Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases.However,the biological characteristics of transplanted mesenchymal stromal cells in hu...Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases.However,the biological characteristics of transplanted mesenchymal stromal cells in humans remain unclear,including cell viability,distribution,migration,and fate.Conventional cell tracing methods cannot be used in the clinic.The use of superparamagnetic iron oxide nanoparticles as contrast agents allows for the observation of transplanted cells using magnetic resonance imaging.In 2016,the National Medical Products Administration of China approved a new superparamagnetic iron oxide nanoparticle,Ruicun,for use as a contrast agent in clinical trials.In the present study,an acute hemi-transection spinal cord injury model was established in beagle dogs.The injury was then treated by transplantation of Ruicun-labeled mesenchymal stromal cells.The results indicated that Ruicunlabeled mesenchymal stromal cells repaired damaged spinal cord fibers and partially restored neurological function in animals with acute spinal cord injury.T2*-weighted imaging revealed low signal areas on both sides of the injured spinal cord.The results of quantitative susceptibility mapping with ultrashort echo time sequences indicated that Ruicun-labeled mesenchymal stromal cells persisted stably within the injured spinal cord for over 4 weeks.These findings suggest that magnetic resonance imaging has the potential to effectively track the migration of Ruicun-labeled mesenchymal stromal cells and assess their ability to repair spinal cord injury.展开更多
Extremely small-sized iron oxide nanoparticles(IONPs) are of great interest in magnetic resonance imaging(MRI) due to their biosafety as an alternative to clinical gadolinium(Ⅲ) complexes-based contrast agents.Especi...Extremely small-sized iron oxide nanoparticles(IONPs) are of great interest in magnetic resonance imaging(MRI) due to their biosafety as an alternative to clinical gadolinium(Ⅲ) complexes-based contrast agents.Especially when the particle size is less than 10 nm,it has strong diffusion ability and deep penetration distance in tumor tissue.Substitution doping can significantly enhance the T_(1)contrast effect of nanoparticles by regulating the surface exposed atoms.However,the nucleation and growth processes of multi-component synthesis systems are complex and difficult to be accurately controlled,leading to great challenges in the synthesis of ultra-small-sized nanoparticles with different components and sizes.Here,extremely smallsized superparamagnetic gadolinium-doped iron oxide nanoparticles(GdIONPs,Gd_(x)Fe_(3-x)O_(4) NPs) with adjustable doping amount and controllable size in the range of 3.5-7.5 nm were synthesized by thermal decomposition.Then,as-synthesized GdIONPs were surface modified with a highly water-soluble and biocompatible carboxyl-polyethylene glycol-phosphoric acid ligand with high binding affinity.Gd_(0.65)Fe_(2.35)O_(4) NPs exhibited very high r_(1) relaxivity of 10.6 mmol^(-1)·L·s^(-1) in terms of all metal concentrations and 49.0 mmol^(-1)·L·s^(-1) in terms of gadolinium alone,respectively,3 and 14 times higher than clinical T_(1) contrast agents(Gd-DTPA).GdIONPs can continuously obtain high resolution images of blood vessels,and can be used as an efficient and multifunctional contrast agent for MR T_(1)imaging.This stable and efficient doping strategy provides an easy and effective method to individually optimize the magnetic properties of complex oxides and their relaxation effects for a variety of biomedical applications.展开更多
The relationship between iron oxides and surface charge characteristics in variable charge soils ( latosol and red earth ) was studied in following three ways. ( 1 ) Remove free iron oxides ( Fed ) and amorphous iron ...The relationship between iron oxides and surface charge characteristics in variable charge soils ( latosol and red earth ) was studied in following three ways. ( 1 ) Remove free iron oxides ( Fed ) and amorphous iron oxides ( Feo ) from the soils with sodium dithionite and acid ammonium oxalate solution respectively. ( 2 ) Add 2% glucose ( on the basis of air-dry soil weight ) to soils and incubate under submerged condition to activate iron oxides, and then the mixtures are dehydrated and air-dried to age iron oxides. ( 3 ) Precipitate various crystalline forms of iron oxides onto kaolinite. The results showed that free iron oxides ( Fed ) were the chief carrier of variable positive charges. Of which crystalline iron oxides ( Fed-Feo ) presented mainly as discrete particles in the soils and could only play a role of the carrier of positive charges, and did little influence on negative charges. Whereas the amorphous iron oxides ( Feo ) , which presented mainly as a coating with a large specific surface area, not only had positive charges, but also blocked the negative charge sites in soils. Submerged incubation activated iron oxides in the soils, and increased the amount of amorphous iron oxides and the degree of activation of iron oxide, which resulted in the increase of positive and negative charges of soils. Dehydration and air-dry aged iron oxides in soils and decreased the amount of amorphous iron oxides and the degree of activation of iron oxide, and also led to the decrease of positive and negative charges. Both the submerged incubation and the dehydration and air-dry had no significant influence on net charges. Precipitation of iron oxides onto kaolinite markedly increased positive charges and decreased negative charges. Amorphous iron oxide having a larger surface area contributed more positive charge sites and blocked more negative charge sites in kaolinite than crystalline goethite.展开更多
Due to their very small size,nanoparticles can interact with all cells in the central nervous system.One of the most promising nanoparticle subgroups are very small superparamagnetic iron oxide nanoparticles(VSOP)that...Due to their very small size,nanoparticles can interact with all cells in the central nervous system.One of the most promising nanoparticle subgroups are very small superparamagnetic iron oxide nanoparticles(VSOP)that are citrate coated for electrostatic stabilization.To determine their influence on murine blood-derived monocytes,which easily enter the injured central nervous system,we applied VSOP and carboxydextran-coated superparamagnetic iron oxide nanoparticles(Resovist).We assessed their impact on the viability,cytokine,and chemokine secretion,as well as iron uptake of murine blood-derived monocytes.We found that(1)the monocytes accumulated VSOP and Resovist,(2)this uptake seemed to be nanoparticle-and time-dependent,(3)the decrease of monocytes viability was treatment-related,(4)VSOP and Resovist incubation did not alter cytokine homeostasis,and(5)overall a 6-hour treatment with 0.75 mM VSOP-R1 was probably sufficient to effectively label monocytes for future experiments.Since homeostasis is not altered,it is safe to label blood-derived monocles with VSOP.VSOP labeled monocytes can be used to study injured central nervous system sites further,for example with drug-carrying VSOP.展开更多
Objective: Application of magnetic nanoparticles as gene carrier in gene therapy has developed quickly. This study was designed to investigate the preparation of superparamagnetic dextran-coated iron oxide nanoparticl...Objective: Application of magnetic nanoparticles as gene carrier in gene therapy has developed quickly. This study was designed to investigate the preparation of superparamagnetic dextran-coated iron oxide nanoparticles (SDION) and the feasibility of SDION used as a novel gene carrier for plasmid DNA in vitro. Methods: SDION were prepared by chemical coprecipitation and separated by gel filtration on Sephacryl S-300HR, characterized by TEM, laser scattering system and Vibrating Sample Magnetometer Signal Processor. The green fluorescent protein (pGFP-C2) plasmid DNA was used as target gene. SDION-pGFP-C2 conjugate compounds were produced by means of oxidoreduction reaction. The connection ratio of SDION and pGFP-C2 DNA was analyzed and evaluated by agarose electrophoresis and the concentration of pGFP-C2 in supernatant was measured. Using liposome as control, the transfection efficiency of SDION and liposome was respectively evaluated under fluorescence microscope in vitro. Results: The diameter of SDION ranges from 3 nm to 8 nm, the effective diameter was 59.2 nm and the saturation magnetization was 0.23 emu/g. After SDION were reasonably oxidized, SDION could connect with pGFP-C2 to a high degree. The transfection efficiency of SDION as gene carrier was higher than that of liposome. Conclusion: The successes in connecting SDION with pGFP-C2 plasmid by means of oxidoreduction reaction and in transferring pGFP-C2 gene into human bladder cancer BIU-87 cells in vitro provided the experimental evidence for the feasibility of SDION used as a novel gene carrier.展开更多
Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed. Influence of external diffusion, internal diffusion and heat transfer on the intrinsi...Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed. Influence of external diffusion, internal diffusion and heat transfer on the intrinsic reaction rate was investigated and the conditions free of internal and external diffusion resistance have been determined. In the experiments, in order to correctly evaluate the intrinsic kinetics parameters for reducing Fe203 to Fe3O4, the reaction temperatures were set between 440 ℃ and 490 ℃. However, in order to distinguish the reduction of Fe304 to FeO from that of FeO to Fe, the reaction temperature in the experiment was set to be greater than 570 ℃. Intrinsic kinetics of iron oxide reduction by hydrogen was established and the newly established kinetic models were validated by the experimental data.展开更多
Erectile dysfunction （ED） is a major complication of diabetes, and many diabetic men with ED are refractory to common ED therapies. Adipose tissue-derived stem cells （ADSCs） have been shown to improve erectile fun...Erectile dysfunction （ED） is a major complication of diabetes, and many diabetic men with ED are refractory to common ED therapies. Adipose tissue-derived stem cells （ADSCs） have been shown to improve erectile function in diabetic animal models. However, inadequate cell homing to damaged sites has limited their efficacy. Therefore, we explored the effect of ADSCs labeled with superparamagnetic iron oxide nanoparticles （SPIONs） on improving the erectile function of streptozotocin-induced diabetic rats with an external magnetic field. We found that SPIONs effectively incorporated into ADSCs and did not exert any negative effects on stem cell properties. Magnetic targeting of ADSCs contributed to long-term cell retention in the corpus cavernosum and improved the erectile function of diabetic rats compared with ADSC injection alone. In addition, the paracrine effect of ADSCs appeared to play the major role in functional and structural recovery. Accordingly, magnetic field-guided ADSC therapy is an effective approach for diabetes-associated ED therapy.展开更多
Reduction of hematite pellets using H2-CO mixtures with a wide range of H2/CO by molar （1：0, 3：1, 1：1, 1：3, and 0：1） at different reducing temperatures （1073, 1173, and 1273 K） was conducted in a program redu...Reduction of hematite pellets using H2-CO mixtures with a wide range of H2/CO by molar （1：0, 3：1, 1：1, 1：3, and 0：1） at different reducing temperatures （1073, 1173, and 1273 K） was conducted in a program reducing furnace. Based on an unreacted core model, the effective diffusion coefficient and reaction rate constant in several cases were determined, and then the rate-control step and transition were analyzed. In the results, the effective diffusion coefficient and reaction rate constant increase with the rise in temperature or hydrogen content. Reduction of iron oxide pellets using an H2-CO mixture is a compound control system; the reaction rate is dominated by chemical reaction at the very beginning, competition during the reduction process subsequently, and internal gas diffusion at the end. At low hydrogen content, increasing temperature takes the transition point of the rate-control step to a high reduction degree, but at high hydrogen content, the effect of temperature on the transition point weakens.展开更多
This study describes a new effective adsorbent for cadmium removal from aqueous solution synthesized by coating a shellac layer, a natural biodegradable and renewable resin with abundant hydroxyl and carboxylic groups...This study describes a new effective adsorbent for cadmium removal from aqueous solution synthesized by coating a shellac layer, a natural biodegradable and renewable resin with abundant hydroxyl and carboxylic groups, on the surface of iron oxide magnetic nanoparticles. Transmission Electron Microscopy （TEM） imaging showed shellac-coated magnetic nanoparticle （SCMN） adsorbents had a core-shell structure with a core of 20 nm and shell of 5 nm. Fourier Transform Infrared Spectroscopic analysis suggested the occurrence of reaction between carboxyl groups on the SCMN adsorbent surface and cadmium ions in aqueous solution. Kinetic data were well described by pseudo second-order model and adsorption isotherms were fitted with both Langmuir and Freundlich models with maximum adsorption capacity of 18.80 mg]g. SCMN adsorbents provided a favorable adsorption capacity under high salinity conditions, and cadmium could easily be desorbed using mild organic acid solutions at low concentration.展开更多
Electromagnetic（EM） wave absorbing cement-based composite has promising applications in protecting civil and military buildings from electromagnetic interferences. A new idea of preparing EM wave absorbing cement-ba...Electromagnetic（EM） wave absorbing cement-based composite has promising applications in protecting civil and military buildings from electromagnetic interferences. A new idea of preparing EM wave absorbing cement-based composite is proposed by using ceramsite containing iron oxide as EM wave absorbing functional aggregate. The ceramsite was synthesized by adding 10 wt% Fe3O4 into clay and sintering at 1 200 ℃, which shows obvious dielectric and magnetic loss properties for electromagnetic wave. The maximum reflection loss（RL） of the concrete specimens prepared with the ceramsite is between-10.2--10.7 dB（corresponding to absorption greater than 90% EM energy） in the bandwidth of 8-18 GHz. In addition, the compressive strength at 28 days age of the concrete is 46 MPa, showing the potentiality of being used as structural components in buildings.展开更多
An efficient and low-cost supported Pt catalyst for hydrogenation of niroarenes was prepared with colloid Pt precursors andα-Fe2O3 as a support.The catalyst with Pt content as low as 0.2 wt%exhibits high activities,c...An efficient and low-cost supported Pt catalyst for hydrogenation of niroarenes was prepared with colloid Pt precursors andα-Fe2O3 as a support.The catalyst with Pt content as low as 0.2 wt%exhibits high activities,chemoselectivities and stability in the hydrogenation of nitrobenzene and a variety of niroarenes.The conversion of nitrobenzene can reach 3170 molconv h^–1 molPt^–1 under mild conditions(30°C,5 bar),which is much higher than that of commercial Pt/C catalyst and many reported catalysts under similar reaction conditions.The spatial separation of the active sites for H2 dissociation and hydrogenation should be responsible for the high chemoselectivity,which decreases the contact possibility between the reducible groups of nitroarenes and Pt nanoparticles.The unique surface properties ofα-Fe2O3 play an important role in the reaction process.It provides active sites for hydrogen spillover and reactant adsorption,and ultimately completes the hydrogenation of the nitro group on the catalyst surface.展开更多
Iron oxide supported Au nanomaterials are one of the most studied catalysts for low-temperature CO oxidation.Catalytic performance not only critically depends on the size of the supported Au nanoparticles(NPs)but also...Iron oxide supported Au nanomaterials are one of the most studied catalysts for low-temperature CO oxidation.Catalytic performance not only critically depends on the size of the supported Au nanoparticles(NPs)but also strongly on the chemical nature of the iron oxide.In this study,Au NPs supported on iron oxide nanorods with different surface properties throughβ-FeOOH annealing,at varying temperatures,were synthesized,and applied in the CO oxidation.Detailed characterizations of the interactions between Au NPs and iron oxides were obtained by X-ray diffraction,transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy.The results indicate that the surface hydroxyl group on the Au/FeOOH catalyst,before calcination(Au/FeOOH-fresh),could facilitate the oxygen adsorption and dissociation on positively charged Au,thereby contributing to the low-temperature CO oxidation reactivity.After calcination at 200℃,under air exposure,the chemical state of the supported Au NP on varied iron oxides partly changed from metal cation to Au0,along with the disappearance of the surface OH species.Au/FeOOH with the highest Au0 content exhibits the highest activity in CO oxidation,among the as-synthesized catalysts.Furthermore,good durability in CO oxidation was achieved over the Au/FeOOH catalyst for 12 h without observable deactivation.In addition,the advanced identical-location TEM method was applied to the gas phase reaction to probe the structure evolution of the Au/iron oxide series of the catalysts and support structure.A Au NP size-dependent Ostwald ripening process mediated by the transport of Au(CO)x mobile species under certain reaction conditions is proposed,which offers a new insight into the validity of the structure-performance relationship.展开更多
Quasi-one dimensional iron oxide nanowires with flat needle shape were synthesized on the iron powders by a rather simple catalyst-free thermal oxidation process in ambient atmosphere. The characterization by field em...Quasi-one dimensional iron oxide nanowires with flat needle shape were synthesized on the iron powders by a rather simple catalyst-free thermal oxidation process in ambient atmosphere. The characterization by field emission scanning electron microscopy （FE-SEM）, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD）, Raman and high-resolution transmission electron microscopy （HRTEM） revealed that these nanos- tructures are single crystalline α-Fe2O3. The various dimensions with 40-170 nm in width and 1-8 μm in length were obtained by tuning the growth temperature from 280 to 480℃. A surface diffusion mechanism was proposed to account for the growth of quasi-one dimensional nanostructure. The typical α-Fe203 nanowires synthesized at 430℃ had a reduced Morin temperature TM of 131 K in comparison with their bulk counterpart. The coercivitis Hc of these nanowires are 321 and 65 Oe at 5 and 300 K, respectively. The temperature of synthesis also has important effects on the magnetic properties of these nanowires.展开更多
The ferrites of PC30 （Mn-Zn ferrites） were prepared by using a dry processing route. The effect of Mn-Zn ferrites doped with H3BO3 was investigated on the basis of microstructure analysis. The results of the samples...The ferrites of PC30 （Mn-Zn ferrites） were prepared by using a dry processing route. The effect of Mn-Zn ferrites doped with H3BO3 was investigated on the basis of microstructure analysis. The results of the samples doped with H3BO3 less than 5 × 10^-5 showed that the doping had no significant effect on power loss, initial permeability, fine grain microstructure, and density of Mn-Zn ferrites. With the further increase in H3BO3 doping （up to 1 × 10 ^-4 ）, the microstructure of Mn-Zn ferrites is in the critical state between fine grain and ＂sandwich＂, and the initial permeability and density of Mn-Zn ferrites begin falling quickly; the increased H3BO3 doping also results in deteriorated power loss properties. Thus, the control of the boron content in iron oxide is of utmost importance for the quality of Mn-Zn ferrites in producing process.展开更多
文摘Ultrasmall superparamagnetic iron oxide nanoparticles(usSPIONs)are promising alternatives to gadolinium‐based contrast agents for positive contrast enhancement in magnetic resonance imaging(MRI).Unlike larger SPIONs that primarily function as T2/T2*negative contrast agents,usSPIONs with core diameters below 5 nm can effectively shorten T1 relaxation times,producing bright signals in T1‐weighted images.This distinct behavior stems from their unique magnetic properties,including single‐domain configurations,surface spin canting,and rapid Néel relaxation dynamics,which are particularly enhanced at low magnetic field strengths.The biocompatibility of iron oxide,efficient renal clearance pathways,and versatility for surface functionalization offer potential advantages over gadolinium‐based agents,especially regarding safety concerns related to nephrogenic systemic fibrosis and gadolinium deposition.These nanoparticles show particular promise for applications in lowfield MRI,vascular imaging,targeted molecular imaging,and theranostic platforms.Although challenges remain in optimizing synthesis methods for consistent production of monodisperse usSPIONs with tailored surface chemistry,ongoing research continues to advance their potential for clinical translation.This review explores the mechanisms,synthesis approaches,applications,and future perspectives of usSPIONs as positive contrast agents in MRI.
基金supported by the Shenyang Municipal Science and Technology Project,China(23-409-2-03)the Liaoning Provincial Department of Science and Technology Project,China(Z20230183)the Liaoning Provincial Applied Basic Research Program,China(2022JH2/101300173).
文摘Both soil organic carbon (SOC) and iron (Fe) oxide content, among other factors, drive the formation and stability of soil aggregates.However, the mechanism of these drivers in greenhouse soil fertilized with organic fertilizer is not well understood.In a 3-year field experiment, we aimed to investigate the factors which drive the stability of soil aggregates in greenhouse soil.To explore the impact of organic fertilizer on soil aggregates, we established four treatments:no fertilization (CK);inorganic fertilizer (CF);organic fertilizer (OF);and combined application of inorganic and organic fertilizers(COF).The application of organic fertilizer significantly enhanced the stability of aggregates, that is it enhanced the mean weight diameter, geometric mean diameter and aggregate content (%) of>0.25 mm aggregate fractions.OF and COF treatments increased the concentration of SOC, especially the aliphatic-C, aromatic-C and polysaccharide-C components of SOC, particularly in>0.25 mm aggregates.Organic fertilizer application significantly increased the content of free Fe(Fed), reactive Fe (Feo), and non-crystalline Fe in both bulk soil and aggregates.Furthermore, non-crystalline Fe showed a positive correlation with SOC content in both bulk soil and aggregates.Both non-crystalline Fe and SOC were significantly positively correlated with>2 mm mean weight diameter.Overall, we believe that the increase of SOC, aromatic-C, and non-crystal ine Fe concentrations in soil after the application of organic fertilizer is the reason for improving soil aggregate stability.
基金supported by the Capacity Building Project of Local University of Shanghai Municipal Science and Technology Commission(No.10230502900)the Program for Shanghai Collaborative Innovation Center for Cultivating Elite Breeds and Green-culture of Aquaculture animals(No.2021-KJ-02-12)the Innovation Project for Chongming Agriculture Industry from Chongming District Agriculture Commission of Shanghai(No.2022CNKC-01-05)。
文摘The efficiency and mechanism of hydrous iron oxide(HFO)and HFO/calcite mixture to inactivate the phosphorus in the overlying water(OW)/sediment system under the feed adding condition were explored,and the effect of HFO and HFO/calcite mixture addition on the diversity,composition and function of bacterial communities in the sediment was examined.HFO and HFO/calcite mixture direct addition can effectively lower the concentration of soluble reactive phosphorus(RSP)and diffusion gradient in thin film-unstable phosphorus(PD GT)in OW and inactivate the P DGTin the upper sediment.The elimination efficiencies of RSP by the direct HFO and HFO/calcite mixture addition were 48.9%-97.0%and 42.4%-95.4%,respectively.The alteration in the addition mode from the one-time to multiple direct addition was beneficial to the immobilization of RSP and PD GTin OW and P DGTin the upper sediment by HFO and HFO/calcite mixture under the feed input condition in the long run.Permeable fabric wrapping reduced the inactivation efficiency of RSP in OW by HFO and HFO/calcite mixture,but it made the recycling of these materials possible.Most of P immobilized by HFO and HFO/calcite mixture was relatively or very stable.After the HFO and HFO/calcite mixture addition,the composition of bacterial communities in the surface sediment changed.However,the bacterial communities in the amended sediments still can perform good ecological function.Our findings suggest that HFO and HFO/calcite mixture are promising phosphorus-immobilization materials for the inactivation of RSP and PD GTin OW and PD GTin the upper sediment under the feed inputting condition.
基金supported by the National Key R&D Program of China(No.2023YFC3708302)the National Natural Science Foundation of China(Nos.22188102 and 22306041)+1 种基金the Chinese Academy of Sciences Project for Young Scientists in Basic Research(No.YSBR-086)China Postdoctoral Science Foundation(No.2023M733679).
文摘Magnetic iron oxide nanoparticles(Fe_(x)O_(y) NPs,mainly Fe3O4 andγ-Fe2O_(3))are nanomaterials ubiquitously present in aquatic,terrestrial,and atmospheric environments,with a high prevalence and complex sources.Over the past decade,numerous reports have emerged on the presence of exogenous particles in human body,facilitated by the rapid development of separation and detection methods.The health risk associated with magnetic Fe_(x)O_(y) NP have garnered escalating attention due to their presence in human blood and brain tissues,especially for their potential association with neurodegenerative diseases like Alzheimer’s disease.In this paper,we provide a comprehensive overview of sources,analysis methods,environmental impacts,and health risks of magnetic Fe_(x)O_(y) NP.Currently,most researches are primarily based on engineered Fe_(x)O_(y) NP,while reports aboutmagnetic Fe_(x)O_(y) NP existing in real-world environments are still limited,especially for their occurrence levels in various environmental matrices,environmental transformation behavior,and biotoxic effects.Our study reviews this emerging pollutant,providing insights to address current research deficiencies and chart the course for future studies.
基金financially supported by the Natural Science Foundation of Zhejiang Province(No.LR22E010001)the National Natural Science Foundation of China(No.52073258)+1 种基金the Fundamental Research Funds for the Provincial Universities of Zhejiang(No.RF-B2022006)the R&D Program of Zhejiang University of Technology(No.KYY-HX-20190730)
文摘Iron oxide nanoparticles(IONPs)with intrinsic peroxidase(POD)-mimic activity have gained significant attention as nanozymes.Reducing sizes of IONPs is the mostly applied strategy to boost their enzymatic activity due to their high specific surface areas.Herein,we synthesized a series of uniformly sized IONPs ranging from3.17 to 21.2 nm,and found that POD activity of IONPs is not monotone increased by reducing their sizes,with the optimal size of 7.82 nm rather than smaller sized 3.17 nm.The reason for this unnormal phenomenon is that electronic structure also had great influence on POD activity,especially at the ultrasmall size region.Since Fe^(2+)are with higher enzymatic activity than Fe^(3+),3.17 nm IONPs although have the largest specific surface area,are prone to be oxidized,which reduced their iron content and ratio of Fe^(2+)to Fe^(3+),and consequently decreased their POD activity.By intentionally oxidized 7.82 nm IONPs in air,POD activity was obviously reduced,illustrating electronic structure cannot be overlooked.At the larger sized region ranging from 7.82 to 21.2 nm,oxidation degree of IONPs is similar,and surface electronic structure had a negligible effect on POD activity,and therefore,POD activity is predominantly influenced by specific surface area.By using the optimized 7.82 nm IONPs,tumor growth was obviously inhibited,demonstrating their potential in cancer therapeutics.Our results reveal that the designing of nanozymes should comprehensively balance their influence of surface electronic structure and specific surface area.
基金supported by the funding from National Natural Science Foundation of China(Nos.32025021,12374390,31971292,82072032,82202274)Ningbo 3315 Innovative Teams Program(No.2019A-14-C)+6 种基金The member of Youth Innovation Promotion Association Foundation of CAS(No.2023310)Key Scientific and Technological Special Project of Ningbo City(Nos.2023Z209,2020Z189)National Key R&D Program of China(No.2019YFA0405603)Provincial Natural Science Foundation of Zhejiang(Nos.LQ23H180007,LQ23H180003)Zhejiang Province Science and Technology Plan of Traditional Chinese Medicine(No.2021KY085)Zhejiang Provincial Traditional Chinese Medicine Foundation(No.2021ZB04)the Major Medical and Health Science and Technology Project of Zhejiang Province(No.WKJ-ZJ-2002)。
文摘Early diagnosis and accurate boundary delineation are the key steps of tumor precision medicine.Circulating tumor cells(CTCs)detection of liquid biopsy can provide abundant information for early diagnosis of cancer.High detection specificity and good enrichment features are two key factors for CTCs accurate identification in peripheral blood sample.For this purpose,iron oxide(IO)-based surface-enhanced Raman scattering(SERS)bioprobes with good biocompatibility,high detection sensitivity,remarkable detection specificity,and good enrichment efficiency,were developed for detecting different types of CTCs.Magnetic SERS bioprobes combined with programmed death ligand-1(PD-L1)antibody are regarded as an effective way to boost the targeting ability and detection specificity,benefiting for accurately capturing and identifying rare CTCs.Four types of CTCs with different PD-L1 expression were accurately distinguished among white blood cells via high-resolution SERS mapping images and stable Raman signals.Subsequently,CTCs blood samples obtained from the triple negative breast cancer patients were also successfully recognized compared to that of health people,indicating IO@AR@PDA-a PD-L1 SERS bioprobe possessed great potential for CTCs detection in liquid biopsy.Additionally,IO-based bioprobe exhibited excellent dual-modal imaging abilities of high-resolution SERS imaging mode and microimaging magnetic resonance imaging mode.These two highly complementary imaging modes endowed IO-based bioprobes unrivalled capacity in tumor boundary differentiation,supporting tumor accurate resection and precise surgery.To our best knowledge,this is the first time that biocompatible IO-based SERS bioprobes without noble metal element were reported not only for CTCs accurate detection,but also for precise tumor boundary delineation,showing great advantages in tumor diagnosis and treatment.
基金supported by the National Key R&D Program of China,Nos.2017YFA0104302(to NG and XM)and 2017YFA0104304(to BW and ZZ)
文摘Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases.However,the biological characteristics of transplanted mesenchymal stromal cells in humans remain unclear,including cell viability,distribution,migration,and fate.Conventional cell tracing methods cannot be used in the clinic.The use of superparamagnetic iron oxide nanoparticles as contrast agents allows for the observation of transplanted cells using magnetic resonance imaging.In 2016,the National Medical Products Administration of China approved a new superparamagnetic iron oxide nanoparticle,Ruicun,for use as a contrast agent in clinical trials.In the present study,an acute hemi-transection spinal cord injury model was established in beagle dogs.The injury was then treated by transplantation of Ruicun-labeled mesenchymal stromal cells.The results indicated that Ruicunlabeled mesenchymal stromal cells repaired damaged spinal cord fibers and partially restored neurological function in animals with acute spinal cord injury.T2*-weighted imaging revealed low signal areas on both sides of the injured spinal cord.The results of quantitative susceptibility mapping with ultrashort echo time sequences indicated that Ruicun-labeled mesenchymal stromal cells persisted stably within the injured spinal cord for over 4 weeks.These findings suggest that magnetic resonance imaging has the potential to effectively track the migration of Ruicun-labeled mesenchymal stromal cells and assess their ability to repair spinal cord injury.
基金financially supported by the Project of High-level Teachers in Beijing Municipal Universities in the Period of 13th Five-Year Plan (No.CIT&TCD201804025)Beijing Municipal Education Commission (No.KM201910011009)the Graduate Student Scientific Research Ability Promotion of BTBU。
文摘Extremely small-sized iron oxide nanoparticles(IONPs) are of great interest in magnetic resonance imaging(MRI) due to their biosafety as an alternative to clinical gadolinium(Ⅲ) complexes-based contrast agents.Especially when the particle size is less than 10 nm,it has strong diffusion ability and deep penetration distance in tumor tissue.Substitution doping can significantly enhance the T_(1)contrast effect of nanoparticles by regulating the surface exposed atoms.However,the nucleation and growth processes of multi-component synthesis systems are complex and difficult to be accurately controlled,leading to great challenges in the synthesis of ultra-small-sized nanoparticles with different components and sizes.Here,extremely smallsized superparamagnetic gadolinium-doped iron oxide nanoparticles(GdIONPs,Gd_(x)Fe_(3-x)O_(4) NPs) with adjustable doping amount and controllable size in the range of 3.5-7.5 nm were synthesized by thermal decomposition.Then,as-synthesized GdIONPs were surface modified with a highly water-soluble and biocompatible carboxyl-polyethylene glycol-phosphoric acid ligand with high binding affinity.Gd_(0.65)Fe_(2.35)O_(4) NPs exhibited very high r_(1) relaxivity of 10.6 mmol^(-1)·L·s^(-1) in terms of all metal concentrations and 49.0 mmol^(-1)·L·s^(-1) in terms of gadolinium alone,respectively,3 and 14 times higher than clinical T_(1) contrast agents(Gd-DTPA).GdIONPs can continuously obtain high resolution images of blood vessels,and can be used as an efficient and multifunctional contrast agent for MR T_(1)imaging.This stable and efficient doping strategy provides an easy and effective method to individually optimize the magnetic properties of complex oxides and their relaxation effects for a variety of biomedical applications.
文摘The relationship between iron oxides and surface charge characteristics in variable charge soils ( latosol and red earth ) was studied in following three ways. ( 1 ) Remove free iron oxides ( Fed ) and amorphous iron oxides ( Feo ) from the soils with sodium dithionite and acid ammonium oxalate solution respectively. ( 2 ) Add 2% glucose ( on the basis of air-dry soil weight ) to soils and incubate under submerged condition to activate iron oxides, and then the mixtures are dehydrated and air-dried to age iron oxides. ( 3 ) Precipitate various crystalline forms of iron oxides onto kaolinite. The results showed that free iron oxides ( Fed ) were the chief carrier of variable positive charges. Of which crystalline iron oxides ( Fed-Feo ) presented mainly as discrete particles in the soils and could only play a role of the carrier of positive charges, and did little influence on negative charges. Whereas the amorphous iron oxides ( Feo ) , which presented mainly as a coating with a large specific surface area, not only had positive charges, but also blocked the negative charge sites in soils. Submerged incubation activated iron oxides in the soils, and increased the amount of amorphous iron oxides and the degree of activation of iron oxide, which resulted in the increase of positive and negative charges of soils. Dehydration and air-dry aged iron oxides in soils and decreased the amount of amorphous iron oxides and the degree of activation of iron oxide, and also led to the decrease of positive and negative charges. Both the submerged incubation and the dehydration and air-dry had no significant influence on net charges. Precipitation of iron oxides onto kaolinite markedly increased positive charges and decreased negative charges. Amorphous iron oxide having a larger surface area contributed more positive charge sites and blocked more negative charge sites in kaolinite than crystalline goethite.
基金supported by Deutsche Forschungsgemeinschaft(DFG)grant Klinische Forschergruppe(KFO)213(to JG).
文摘Due to their very small size,nanoparticles can interact with all cells in the central nervous system.One of the most promising nanoparticle subgroups are very small superparamagnetic iron oxide nanoparticles(VSOP)that are citrate coated for electrostatic stabilization.To determine their influence on murine blood-derived monocytes,which easily enter the injured central nervous system,we applied VSOP and carboxydextran-coated superparamagnetic iron oxide nanoparticles(Resovist).We assessed their impact on the viability,cytokine,and chemokine secretion,as well as iron uptake of murine blood-derived monocytes.We found that(1)the monocytes accumulated VSOP and Resovist,(2)this uptake seemed to be nanoparticle-and time-dependent,(3)the decrease of monocytes viability was treatment-related,(4)VSOP and Resovist incubation did not alter cytokine homeostasis,and(5)overall a 6-hour treatment with 0.75 mM VSOP-R1 was probably sufficient to effectively label monocytes for future experiments.Since homeostasis is not altered,it is safe to label blood-derived monocles with VSOP.VSOP labeled monocytes can be used to study injured central nervous system sites further,for example with drug-carrying VSOP.
基金This project was supported by a grant from the National Natural Science Foundation of China (No. 30271300).
文摘Objective: Application of magnetic nanoparticles as gene carrier in gene therapy has developed quickly. This study was designed to investigate the preparation of superparamagnetic dextran-coated iron oxide nanoparticles (SDION) and the feasibility of SDION used as a novel gene carrier for plasmid DNA in vitro. Methods: SDION were prepared by chemical coprecipitation and separated by gel filtration on Sephacryl S-300HR, characterized by TEM, laser scattering system and Vibrating Sample Magnetometer Signal Processor. The green fluorescent protein (pGFP-C2) plasmid DNA was used as target gene. SDION-pGFP-C2 conjugate compounds were produced by means of oxidoreduction reaction. The connection ratio of SDION and pGFP-C2 DNA was analyzed and evaluated by agarose electrophoresis and the concentration of pGFP-C2 in supernatant was measured. Using liposome as control, the transfection efficiency of SDION and liposome was respectively evaluated under fluorescence microscope in vitro. Results: The diameter of SDION ranges from 3 nm to 8 nm, the effective diameter was 59.2 nm and the saturation magnetization was 0.23 emu/g. After SDION were reasonably oxidized, SDION could connect with pGFP-C2 to a high degree. The transfection efficiency of SDION as gene carrier was higher than that of liposome. Conclusion: The successes in connecting SDION with pGFP-C2 plasmid by means of oxidoreduction reaction and in transferring pGFP-C2 gene into human bladder cancer BIU-87 cells in vitro provided the experimental evidence for the feasibility of SDION used as a novel gene carrier.
基金Supported by the National Natural Science Foundation of China (20736004)the State Key Development Program for Basic Research of China (2007CB613502)
文摘Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed. Influence of external diffusion, internal diffusion and heat transfer on the intrinsic reaction rate was investigated and the conditions free of internal and external diffusion resistance have been determined. In the experiments, in order to correctly evaluate the intrinsic kinetics parameters for reducing Fe203 to Fe3O4, the reaction temperatures were set between 440 ℃ and 490 ℃. However, in order to distinguish the reduction of Fe304 to FeO from that of FeO to Fe, the reaction temperature in the experiment was set to be greater than 570 ℃. Intrinsic kinetics of iron oxide reduction by hydrogen was established and the newly established kinetic models were validated by the experimental data.
文摘Erectile dysfunction （ED） is a major complication of diabetes, and many diabetic men with ED are refractory to common ED therapies. Adipose tissue-derived stem cells （ADSCs） have been shown to improve erectile function in diabetic animal models. However, inadequate cell homing to damaged sites has limited their efficacy. Therefore, we explored the effect of ADSCs labeled with superparamagnetic iron oxide nanoparticles （SPIONs） on improving the erectile function of streptozotocin-induced diabetic rats with an external magnetic field. We found that SPIONs effectively incorporated into ADSCs and did not exert any negative effects on stem cell properties. Magnetic targeting of ADSCs contributed to long-term cell retention in the corpus cavernosum and improved the erectile function of diabetic rats compared with ADSC injection alone. In addition, the paracrine effect of ADSCs appeared to play the major role in functional and structural recovery. Accordingly, magnetic field-guided ADSC therapy is an effective approach for diabetes-associated ED therapy.
基金financially supported by the National Natural Science Foundation of China (Nos. 51104014 and 51134008)
文摘Reduction of hematite pellets using H2-CO mixtures with a wide range of H2/CO by molar （1：0, 3：1, 1：1, 1：3, and 0：1） at different reducing temperatures （1073, 1173, and 1273 K） was conducted in a program reducing furnace. Based on an unreacted core model, the effective diffusion coefficient and reaction rate constant in several cases were determined, and then the rate-control step and transition were analyzed. In the results, the effective diffusion coefficient and reaction rate constant increase with the rise in temperature or hydrogen content. Reduction of iron oxide pellets using an H2-CO mixture is a compound control system; the reaction rate is dominated by chemical reaction at the very beginning, competition during the reduction process subsequently, and internal gas diffusion at the end. At low hydrogen content, increasing temperature takes the transition point of the rate-control step to a high reduction degree, but at high hydrogen content, the effect of temperature on the transition point weakens.
基金supported by the National Natural Science Foundation of China (No. 50808070, 51039001)the Program for New Century Excellent Talents in University from the Ministry of Education of China (No. NCET-09-0328)+4 种基金the Postdoctoral Science Foundation of China (No.20070410301, 200902468)the Program for Changjiang Scholars and Innovative Research Team in University(No. IRT0719)the Hunan Provincial Natural Science Foundation of China (No. 08JJ4006, 10JJ7005)the Xiangjiang Water Environmental Pollution Control Project subjected to the National Key Science and Technology Project for Water Environmental Pollution Control (No.2009ZX07212-001-02, 2009ZX07212-001-06)the Hunan Key Scientific Research Project (No. 2009FJ1010)
文摘This study describes a new effective adsorbent for cadmium removal from aqueous solution synthesized by coating a shellac layer, a natural biodegradable and renewable resin with abundant hydroxyl and carboxylic groups, on the surface of iron oxide magnetic nanoparticles. Transmission Electron Microscopy （TEM） imaging showed shellac-coated magnetic nanoparticle （SCMN） adsorbents had a core-shell structure with a core of 20 nm and shell of 5 nm. Fourier Transform Infrared Spectroscopic analysis suggested the occurrence of reaction between carboxyl groups on the SCMN adsorbent surface and cadmium ions in aqueous solution. Kinetic data were well described by pseudo second-order model and adsorption isotherms were fitted with both Langmuir and Freundlich models with maximum adsorption capacity of 18.80 mg]g. SCMN adsorbents provided a favorable adsorption capacity under high salinity conditions, and cadmium could easily be desorbed using mild organic acid solutions at low concentration.
基金Funded by the National Natural Science Foundation of China(Nos.51372183,50902106,51461135005)Program for New Century Excellent Talents in University(No.NCET-10-0660)
文摘Electromagnetic（EM） wave absorbing cement-based composite has promising applications in protecting civil and military buildings from electromagnetic interferences. A new idea of preparing EM wave absorbing cement-based composite is proposed by using ceramsite containing iron oxide as EM wave absorbing functional aggregate. The ceramsite was synthesized by adding 10 wt% Fe3O4 into clay and sintering at 1 200 ℃, which shows obvious dielectric and magnetic loss properties for electromagnetic wave. The maximum reflection loss（RL） of the concrete specimens prepared with the ceramsite is between-10.2--10.7 dB（corresponding to absorption greater than 90% EM energy） in the bandwidth of 8-18 GHz. In addition, the compressive strength at 28 days age of the concrete is 46 MPa, showing the potentiality of being used as structural components in buildings.
基金supported by the National Natural Science Foundation of China(21473073,21473074)‘‘13th Five-Year’’ Science and Technology Research of the Education Department of Jilin Province(2016403)+1 种基金the Development Project of Science and Technology of Jilin Province(20170101171JC,20180201068SF)the Open Project of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry(201703)~~
文摘An efficient and low-cost supported Pt catalyst for hydrogenation of niroarenes was prepared with colloid Pt precursors andα-Fe2O3 as a support.The catalyst with Pt content as low as 0.2 wt%exhibits high activities,chemoselectivities and stability in the hydrogenation of nitrobenzene and a variety of niroarenes.The conversion of nitrobenzene can reach 3170 molconv h^–1 molPt^–1 under mild conditions(30°C,5 bar),which is much higher than that of commercial Pt/C catalyst and many reported catalysts under similar reaction conditions.The spatial separation of the active sites for H2 dissociation and hydrogenation should be responsible for the high chemoselectivity,which decreases the contact possibility between the reducible groups of nitroarenes and Pt nanoparticles.The unique surface properties ofα-Fe2O3 play an important role in the reaction process.It provides active sites for hydrogen spillover and reactant adsorption,and ultimately completes the hydrogenation of the nitro group on the catalyst surface.
基金supported by the National Natural Science Foundation of China(21773269,21761132025,91545119,21703262)the Youth Innovation Promotion Association CAS(2015152)+1 种基金the Joint Foundation of Liaoning Province Natural Science FoundationShenyang National Laboratory for Materials Science(20180510047)~~
文摘Iron oxide supported Au nanomaterials are one of the most studied catalysts for low-temperature CO oxidation.Catalytic performance not only critically depends on the size of the supported Au nanoparticles(NPs)but also strongly on the chemical nature of the iron oxide.In this study,Au NPs supported on iron oxide nanorods with different surface properties throughβ-FeOOH annealing,at varying temperatures,were synthesized,and applied in the CO oxidation.Detailed characterizations of the interactions between Au NPs and iron oxides were obtained by X-ray diffraction,transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy.The results indicate that the surface hydroxyl group on the Au/FeOOH catalyst,before calcination(Au/FeOOH-fresh),could facilitate the oxygen adsorption and dissociation on positively charged Au,thereby contributing to the low-temperature CO oxidation reactivity.After calcination at 200℃,under air exposure,the chemical state of the supported Au NP on varied iron oxides partly changed from metal cation to Au0,along with the disappearance of the surface OH species.Au/FeOOH with the highest Au0 content exhibits the highest activity in CO oxidation,among the as-synthesized catalysts.Furthermore,good durability in CO oxidation was achieved over the Au/FeOOH catalyst for 12 h without observable deactivation.In addition,the advanced identical-location TEM method was applied to the gas phase reaction to probe the structure evolution of the Au/iron oxide series of the catalysts and support structure.A Au NP size-dependent Ostwald ripening process mediated by the transport of Au(CO)x mobile species under certain reaction conditions is proposed,which offers a new insight into the validity of the structure-performance relationship.
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry of China, the Natural Science Foundation of China (Grant Nos. U0734001, 50874050)the Fundamental Research Funds for the Central Universities, SCUT (Grant No. 2009ZZ0025)
文摘Quasi-one dimensional iron oxide nanowires with flat needle shape were synthesized on the iron powders by a rather simple catalyst-free thermal oxidation process in ambient atmosphere. The characterization by field emission scanning electron microscopy （FE-SEM）, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD）, Raman and high-resolution transmission electron microscopy （HRTEM） revealed that these nanos- tructures are single crystalline α-Fe2O3. The various dimensions with 40-170 nm in width and 1-8 μm in length were obtained by tuning the growth temperature from 280 to 480℃. A surface diffusion mechanism was proposed to account for the growth of quasi-one dimensional nanostructure. The typical α-Fe203 nanowires synthesized at 430℃ had a reduced Morin temperature TM of 131 K in comparison with their bulk counterpart. The coercivitis Hc of these nanowires are 321 and 65 Oe at 5 and 300 K, respectively. The temperature of synthesis also has important effects on the magnetic properties of these nanowires.
文摘The ferrites of PC30 （Mn-Zn ferrites） were prepared by using a dry processing route. The effect of Mn-Zn ferrites doped with H3BO3 was investigated on the basis of microstructure analysis. The results of the samples doped with H3BO3 less than 5 × 10^-5 showed that the doping had no significant effect on power loss, initial permeability, fine grain microstructure, and density of Mn-Zn ferrites. With the further increase in H3BO3 doping （up to 1 × 10 ^-4 ）, the microstructure of Mn-Zn ferrites is in the critical state between fine grain and ＂sandwich＂, and the initial permeability and density of Mn-Zn ferrites begin falling quickly; the increased H3BO3 doping also results in deteriorated power loss properties. Thus, the control of the boron content in iron oxide is of utmost importance for the quality of Mn-Zn ferrites in producing process.
