Enhanced UV-B radiation represents a major environmental factor impacting global cereal production.Researchers have explored various approaches to reduce the detrimental impact of UV-B radiation on crops.Recently,engi...Enhanced UV-B radiation represents a major environmental factor impacting global cereal production.Researchers have explored various approaches to reduce the detrimental impact of UV-B radiation on crops.Recently,engineered nanoparticles,particularly cerium oxide nanoparticles(CeO_(2)-NPs),have attracted widespread interest for their ability to boost plant tolerance to a range of abiotic stresses.This study investigates how CeO_(2)-NPs application affects the morphology,physiology,biochemistry,and transcriptomics profiles of wheat seedling roots subjected to enhanced UV-B stress.The findings demonstrate that CeO_(2)-NPs notably promoted root length,fresh and dry weights,and root activity(p<0.05)under enhanced UV-B stress.CeO_(2)-NP treatment reduced the content of hydrogen peroxide<(H_(2)O_(2))and malondialdehyde(MDA)in wheat,alleviating oxidative damage in seedling roots and partially restoring the root phenotype.Under non-UV-B stress conditions,CeO_(2)-NP treatment triggered the difference of 237 transcripts in plants relative to the control group.Under enhanced UV-B stress,CeO_(2)-NP treatment exhibited differentially expressed genes(DEGs)linked to the antioxidant defense mechanism responsible for reactive oxygen species(ROS)scavenging,compared to the non-nanoparticle control.This suggests that ROS scavenging may be a key mechanism by which CeO_(2)-NPs enhance wheat resistance to enhanced UV-B radiation.This study elucidates a potential molecular mechanism through which CeO_(2)nanoparticles may enhance wheat tolerance to UV-B stress.展开更多
Rare earth carbonates are essential precursors for the synthesis of oxide materials.In this study,we utilized in situ monitoring equipment to explore the alterations in the crystallization during the coprecipitation s...Rare earth carbonates are essential precursors for the synthesis of oxide materials.In this study,we utilized in situ monitoring equipment to explore the alterations in the crystallization during the coprecipitation synthesis of cerium carbonate.By controlling the crystallization pathway and in the absence of any te mplating agents,we successfully synthesized a unique sphe rical self-assembled cerium oxide particle(Ceria-S).The Ceria-S exhibits excellent polishing performance.The crystallization process of cerium carbonate at 50℃persists for roughly 50 min.During the initial stages of crystallization from 0 to t_(3),the precipitated particles are amorphous.This is followed by a plateau phase of crystal growth from t_(3)to t_(5).Subsequently,during the burst crystallization phase from t_(5)to t_(6),Ce_(2)(CO_(3))_(3)·6H_(2)O and Ce_(2)O(CO_(3))_(2)·nH2O are formed,exhibiting a rod-like crystal morphology.By rapidly drying the precipitated particles at 60℃for 10 min and calcining,Ceria-S is obtained.The Ceria-S,with an average diameter of 180 nm,is assembled from primary cerium oxide nanoparticles of approximately 15 nm.Owing to the self-assembly structure of cerium oxide spherical nanoparticles,they exhibit a significantly larger specific surface area,resulting in an elevated concentration of Ce^(3+)as high as 35.5%.The Ceria-S exhibits a polishing removal rate of 420 nm/min,effectively decreasing the surface roughness(S_(a))of K9 glass from 1.605 to 0.404 nm.展开更多
It is challenging to assess the mechanism responsible for the nucleation of inclusions in metals at high temperatures.The present work therefore systematically investigates the nucleation of cerium oxide inclusions ac...It is challenging to assess the mechanism responsible for the nucleation of inclusions in metals at high temperatures.The present work therefore systematically investigates the nucleation of cerium oxide inclusions according to classical nucleation theory and a two-step nucleation mechanism.The nucleation rates and nucleation radii of these inclusions are obtained,and the results demonstrate a considerable difference between theoretical and experimental values.On the basis of a two-step nucleation mechanism,(CeO_(2))_(n) and(Ce_(2)O_(3))_(n)(n=1-6)clusters were constructed and the thermodynamic properties of both these clusters and of cerium oxide nanoparticles were analyzed.In addition,the entropies and heat capacity changes of cerium oxides were determined using first principles calculations and are found to be consistent with literature data.The present data indicate that the cerium oxide inclusion nucleation pathway can be summarized as[Ce]+[O]→(CeO_(2))n/(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(2)→core(Ce_(2)O_(3)crystal)-shell((Ce_(2)O_(3))_(2) cluster)nanoparticles→(Ce_(2)O_(3))bulk.展开更多
Electrospinning technique was used to fabricate PVP/Ce（NO3）3 composite microfibers. Different morphological CeO2 nanofibers were obtained by calcination of the PVP/Ce（NO3）3 composite microfibers and were character...Electrospinning technique was used to fabricate PVP/Ce（NO3）3 composite microfibers. Different morphological CeO2 nanofibers were obtained by calcination of the PVP/Ce（NO3）3 composite microfibers and were characterized by scanning electron microscopy （SEM）, Transmission electron microscopy （TEM）, X-ray diffraction （XRD）, thermal gravimetric and differential thermal analysis （TG-DTA）, and （FTIR）. SEM micrographs indicated that the surface of the composite fibers was smooth and became coarse with the increase of calcination temperatures. The diameters of CeO2 hollow nanofibers （300 nm at 600 ℃ and 600 nm at 800 ℃ ） were smaller than those of PVP/Ce（NO3）3 composite fibers （1-2 um ）. CeO2 hollow nanofibers were obtained at 600 ℃ and CeO2 hollow and porous nanofibers formed by nanoparti- cles were obtained at 800 ℃. The length of the CeO2 hollow nanofibers was greater than 50 um. XRD analysis revealed that the composite microfibers were amorphous in structure and CeO2 nanofibers were cubic in structure with space group O^5H - FM3m when calcination tem- peratures were 600-800 ℃. TG-DTA and FTIR revealed that the formation of CeO2 nanofibers was largely influenced by the calcination temperatures. Possible formation mechanism of CeO2 hollow nanofibers was proposed.展开更多
Nanostructured cerium oxide （CeO2） commonly known as nanoceria is a rare earth metal oxide, which plays a technologically important role due to its versatile applications as antomobile exhaust catalysts, oxide ion c...Nanostructured cerium oxide （CeO2） commonly known as nanoceria is a rare earth metal oxide, which plays a technologically important role due to its versatile applications as antomobile exhaust catalysts, oxide ion conductors in solid oxide fuel cells, electrode materials for gas sensors, ultraviolet absorbents and glass-polishing materials. However, nanoceria has little or weak luminescence, and therefore its uses in high-performance luminescent devices and biomedical areas are limited. In this review, we present the recent advances of nanoceria in the aspects of synthesis, luminescence and biomedical studies. The CeO2 nanoparticles can bc synthesized by solution-based methods including co-precipitation, hydrothemlal, microemulsion process, sol-gel techniques, combustion reaction and so on. Achieving controlled morphologies and enhanced luminescence efficiency of nanoceria particles arc quite essential for its potential energyand environment-related applications. Additionally, a new fiontier for nanoccria particles in biomedical research has also been opened, which involves low toxicity, retinopathy, biosensors and cancer therapy aspects. Finally, the summary and outlook on the challenges and perspectives of the nanoceria particles are proposed.展开更多
Nanotechnology deals with particles ranging from 1 to 100 nm in size called as nanoparticles.These nano particles exhibit unique properties which find an application in many industries and medical fields.A growing bod...Nanotechnology deals with particles ranging from 1 to 100 nm in size called as nanoparticles.These nano particles exhibit unique properties which find an application in many industries and medical fields.A growing body of evidence points out the newer developing technologies adopted in the field of medicine in terms of target therapies,imaging systems,drug deliveries,etc.is through the incorporation of nanoparticles.Cerium oxide nanoparticles have gained attention in the last decade due to exceptional properties such as redox activity,biofilm inhibition,antibacterial activity,anti-inflammatory activity,etc.The method of synthesis of cerium oxide nanoparticles plays a pivotal role in its application.It exhibits redox properties and catalytic activity and thus has found its use in biomedical applications.Nanoparticles are incorporated into dental materials such as restorative cements/sealants,adhesives,and denture systems to improve their properties.Among the various metal oxide nanoparticles,ce rium oxide nanoparticles(CeO_(2)NPs)are known to exhibit lower toxicity to mammalian cells and possess unique antibacterial mechanism.In addition,they exhibit potent properties such as antitumor,antiinflammatory,antibacterial activities,and functions as an immunosensor.CeO_(2)NPs have excellent scavenging properties for reactive oxygen species,which is why they are being considered for therapeutic purposes.In this review,various methods of synthesis of CeO_(2)NPs are discussed.Several factors that determine the particle size and morphology of these materials are important for biomedical and dental applications.Emphasis is given to preparation methods and variables such as calcination temperature,which have a profound effect on particle size and morphology.This article also presents various applications of CeO_(2)NPs in the biomedical and dental fields.展开更多
A new method for the separation and detection of trace metal impurities in cerium oxide (CeO_2) using HPLC combined with electrothermal vaporization (ETV)-ICP-AES was developed. This combination links the high separat...A new method for the separation and detection of trace metal impurities in cerium oxide (CeO_2) using HPLC combined with electrothermal vaporization (ETV)-ICP-AES was developed. This combination links the high separation power of HPLC and high sensitivity of ETV-ICP-AES. The 2-ethylhexyl hydrogen 2-ethylhexylphosphate (P_(507)) resin was used as stationary phase for the separation of metallic impurities in order to eliminate severe spectral interferences of the matrix. The dilute nitric acid was adopted as mobile phase for eluting Cu, Mn, Ni and La. The separation process can be accomplished in about 30 min. After concentrating the eluate by evaporation, the trace impurities were determined by using ETV-ICP-AES with the addition of 6% PTFE slurry as chemical modifier. The proposed method was applied to the analysis of CeO_2 with satisfactory recoveries.展开更多
Nano cerium oxide films were applied on AA7020-T6 aluminum alloy and the effects of acetic acid concentration on the microstructure and electrochemical properties of the coated samples were investigated by using scann...Nano cerium oxide films were applied on AA7020-T6 aluminum alloy and the effects of acetic acid concentration on the microstructure and electrochemical properties of the coated samples were investigated by using scanning electron microscopy （SEM）, X-ray diffraction （XRD）, and potentiodynamic polarization methods. It has been found that by increasing the acetic acid/CeCl3·7H2O molar ratio, high uniform and crack-free films with well-developed grains were obtained and grain sizes of the films decreased. Elimination of cracks and decreasing grain size of the nano cerium oxide films caused corrosion resistance to increase.展开更多
Cerium oxide nanoparticles(CNPs)possess a great potential as therapeutic agents due to their ability to self-regenerate by reversibly switching between two valences+3 and+4.This article reviews recent articles dealing...Cerium oxide nanoparticles(CNPs)possess a great potential as therapeutic agents due to their ability to self-regenerate by reversibly switching between two valences+3 and+4.This article reviews recent articles dealing with in vivo studies of CNPs towards Alzheimer’s disease,obesity,liver inflammation,cancer,sepsis,amyotrophic lateral sclerosis,acute kidney injury,radiation-induced tissue damage,hepatic ischemia reperfusion injury,retinal diseases and constipation.In vivo anti-cancer studies revealed the effectiveness of CNPs to reduce tumor growth and angiogenesis in melanoma,ovarian,breast and retinoblastoma cancer cell-induced mice,with their conjugation with folic acid,doxorubicin,CPM,or CXC receptor-4 antagonist ligand eliciting higher efficiency.After conjugation with triphenylphosphonium or magnetite nanoparticles,CNPs were shown to combat Alzheimer’s disease by reducing amyloid-β,glial fibrillary acidic protein,inflammatory and oxidative stress markers in mice.By improving muscle function and longevity,the citrate/EDTA-stabilized CNPs could ameliorate amyotrophic lateral sclerosis.Also,they could effectively reduce obesity in mice by scavenging ROS and reducing adipogenesis,triglyceride synthesis,GAPDH enzyme activity,leptin and insulin levels.In CCl4-induced rats,stress signaling pathways due to inflammatory cytokines,liver enzymes,oxidative and endoplasmic reticulum messengers could be attenuated by CNPs.Commercial CNPs showed protective effects on rats with hepatic ischemia reperfusion and peritonitis-induced hepatic/cardiac injuries by decreasing oxidative stress and hepatic/cardiac inflammation.The same CNPs could improve kidney function by diminishing renal superoxide,hyperglycemia and tubular damage in peritonitis-induced acute kidney injury in rats.Radiation-induced lung and testicular tissue damage could be alleviated in mice,with the former showing improvement in pulmonary distress and bronchoconstriction and the latter exhibiting restoration in spermatogenesis rate and spermatid/spermatocyte number.Through enhancement of gastrointestinal motility,the CNPs could alleviate constipation in both young and old rats.They could also protect rat from light-induced retinal damage by slowing down neurodegenerative process and microglial activation.展开更多
Variable masses of nano cerium oxide (CeO2) were added into nano silica (SiO2) to prepare the well-dispersed SiO2-CeO2 suspension (SiO2-CeO2), cetyltrimethyl ammonium bromide (CTAB) was used to adjust the compatibilit...Variable masses of nano cerium oxide (CeO2) were added into nano silica (SiO2) to prepare the well-dispersed SiO2-CeO2 suspension (SiO2-CeO2), cetyltrimethyl ammonium bromide (CTAB) was used to adjust the compatibility of SiO2-CeO2 with rubber matrix, then SiO2-CeO2 modified by CTAB and curing formulas were mixed with fresh natural rubber (NR) latex to prepare NR/SiO2-CeO2 nanocomposites that contained 0–10 parts of CeO2 by a new emulsion compounding method. The morphologies, cure characteristics, mechanical properties and thermal-oxidative stability of NR/SiO2-CeO2 nanocomposites were investigated. The re-sults revealed that the presence of CeO2 in NR/SiO2-CeO2nanocomposites was favorable for enhancing the interaction between NR matrix and fillers, helped to get smaller SiO2-CeO2 particles with narrower particle size distribution, further improved the crosslink densities and mechanical properties of NR/SiO2-CeO2 nanocomposites vulcanizates. Meanwhile, the addition of CeO2 increased the active energy at least 4.66%, obviously improved the thermal-oxidative aging-inhibiting properties of NR/SiO2-CeO2 nanocomposites. Additionally, nanocomposites containing CeO2 promotedTg shift to high temperature direction, causing the nanocomposites featured higher tanδ at 0 oC and lower tanδ at 60 oC and exhibited comparable wet grip and lower rolling resistance when NR/SiO2-CeO2nano-composites were used in tire tread compound.展开更多
Characteristics of carbon deposition of CH 4 and C 2H 4 decomposition over supported Ni and Ni Ce catalysts were studied by using a pulse reaction as well as BET, TPR, XPS and hydrogen chemisorption techniques. It...Characteristics of carbon deposition of CH 4 and C 2H 4 decomposition over supported Ni and Ni Ce catalysts were studied by using a pulse reaction as well as BET, TPR, XPS and hydrogen chemisorption techniques. It is found that there is a metal semiconductor interaction (MScI) in the Ni Ce catalyst, and the effect of MScI on the carbon deposition of CH 4 decomposition is opposite to that of C 2H 4. A novel model of carbon deposition of CH 4 or C 2H 4 decomposition was proposed.展开更多
During the previous years, with the emerging of nanotechnology, the enormous capabilities of nanoparticles have drawn great attention from researchers in terms of their potentials in various aspects of pharmacology. C...During the previous years, with the emerging of nanotechnology, the enormous capabilities of nanoparticles have drawn great attention from researchers in terms of their potentials in various aspects of pharmacology. Cerium oxide nanoparticles（nanoceria）, considered as one of the most widely used nanomaterials, due to its tempting catalytic antioxidant properties, show a promising potential in diverse disorders, such as cerebral ischemic stroke（CIS）, cancer, neurodegenerative and inflammatory diseases. Overwhelming generation of reactive oxygen species（ROS） and reactive nitrogen species（RNS） during cerebral ischemia and reperfusion periods is known to aggravate brain damage via sophisticated cellular and molecular mechanisms, and therefore exploration of the antioxidant capacities of nanoceria becomes a new approach in reducing cerebral ischemic injury. Furthermore, utilizing nanoceria as a drug carrier might display the propensity to overcome limitations or inefficacy of other conceivable neuroprotectants and exhibit synergistic effects. In this review, we emphasize on the principle features of nanoceria and current researches concerning nanoceria as a potential therapeutic agent or carrier in improving the prognosis of CIS.展开更多
The large particle cerium oxide was prepared using oxalic acid as precipitation agent. The effects of preparation conditions on the particle size of cerium oxide were discussed. The results showed that the particle si...The large particle cerium oxide was prepared using oxalic acid as precipitation agent. The effects of preparation conditions on the particle size of cerium oxide were discussed. The results showed that the particle size of cerium oxide could be controlled effectively by the temperature,acidity of the solution,aging time,etc. The optimized preparation process of large particle cerium oxide was obtained. The cerium oxide with size between 50 μm to 150 μm was prepared by the process. Moreover,the cerium oxide particles were dispersed uniformly.展开更多
Ultrafine rare-earth oxides(REOs) are widely applied in all fields of daily life,but the conventional preparation methods are limited by a long procedure,low efficiency and severe environmental pollution.Our team has ...Ultrafine rare-earth oxides(REOs) are widely applied in all fields of daily life,but the conventional preparation methods are limited by a long procedure,low efficiency and severe environmental pollution.Our team has independently developed a jet pyrolysis reactor for the preparation of ultrafine cerium oxides,and this process has theoretical significance and practical application values.In this study,gas-solid pyrolysis reactions inside the jet-flow pyrolysis reactor were numerically simulated.We performed a coupling computation of the combustion,phase transformation and gas-solid reaction on Fluent and userdefined functions.We characterized the flows of different phases as well as the compositions and distributive laws of the reactants/products in the reactor.The gas-phase inlet velocity and dynamic pressure/additional pressure were related by a quadratic function.The velocity at the throat inlet changed the most,and the outlet velocity was very stable.The CeO2 concentrations were obviously stratified.This study enriches theories of jet-flow pyrolysis and theoretically underlies the optimization and popularization of self-developed pyrolysis reactors.展开更多
One of the main problems of stainless steel is its poor pitting corrosion resistance in the aggressive environment containing Cl-, such as seawater. In this paper we investigated the corrosion behavior of the 316 stai...One of the main problems of stainless steel is its poor pitting corrosion resistance in the aggressive environment containing Cl-, such as seawater. In this paper we investigated the corrosion behavior of the 316 stainless steel coated by cerium oxide nanocoating prepared by sol-gel process. Potentiodynamic polarization and electrochemical impedance spectroscopy （EIS） were used to study the corrosion behavior of cerium oxide nanocoatings in 3.5% NaCl solution. The microstructure of the cerium oxide was examined by scanning electron microscopy （SEM） and the formed phases was identified by X-ray diffraction （XRD）. The pitting corrosion resistance of the cerium oxide nanocoating was found to be improved after heat treatment of the cerium oxide nanocoating at 300℃ for 30 min.展开更多
In general, inorganic filler/polyurethane elastomer(PUE) composites possess favorable properties, such as modulus, chemical resistance, and heat stability, are promising for broadening the application area of polyuret...In general, inorganic filler/polyurethane elastomer(PUE) composites possess favorable properties, such as modulus, chemical resistance, and heat stability, are promising for broadening the application area of polyurethanes(PU). For the experiments, a series of cerium oxide(CeO_(2))/PUE composites were prepared with different sizes and appearance of CeO_(2), and different mixing methods as well. CeO_(2) particles with different sizes were added into PUs during the formation of urethane linkage and the chain-extend process, respectively. The morphology along with mechanical properties, thermal properties of the composites were studied. The results suggest that the size of CeO_(2) and mixing methods influence the microstructure of PUs which has profound effect on properties of these composites. The composites tend to form more quantity of hard domains(HDs) with small size when CeO_(2) particles were added before the formation of urethane linkage, whereas Ce O2 particles increase the size of HDs when added with chain extender into PU prepolymer.展开更多
Study was made on the effect of surface modification on the behaviors of cerium oxide nanopowders.A surfactant-sodium dodecyl sulfate（C12H25SO4Na）was used to modify the surface of CeO2 powder particles.The unmodifie...Study was made on the effect of surface modification on the behaviors of cerium oxide nanopowders.A surfactant-sodium dodecyl sulfate（C12H25SO4Na）was used to modify the surface of CeO2 powder particles.The unmodified and modified CeO2 powders were characterized by using a powder comprehensive characteristic tester,laser particle size analyzer,specific surface area tester,X-ray diffraction tester,and a scanning electron microscope.The testing and analysis results showed that C12H25SO4Na surface modification might increase the flowability and dispersity,and decrease the specific surface area and agglomeration of CeO2 powders.The mechanism of the surface modification of CeO2 powder particles was also discussed.展开更多
Cerium oxide possesses intrinsic hydrophobic properties ascribed to the unique electronic structure.However,the relationship between the crystal structure and hydrophobicity of cerium oxide has not been systematically...Cerium oxide possesses intrinsic hydrophobic properties ascribed to the unique electronic structure.However,the relationship between the crystal structure and hydrophobicity of cerium oxide has not been systematically studied.Herein,it is experimentally and theoretically demonstrated that the water contact angle(105.9°)of the(111)surface is higher than that(91.7°)of the(220)surface,associated with the lower surface free energy(28.44 mN/m)of(111)surface than that(38.48 mN/m)of(220)surface.Furthermore,cerium oxide films with(111)-terminated surface are annealed at 300℃ and 600℃ for1 h,respectively.The lattice constant increases(5.4594Å<5.4613Å<5.4670Å)with decreasing the annealing temperature(600℃>300℃>the as-deposited),leading to the increased water contact angle(96.7°<96.8°<99.0°).The First-principles calculation provides microscopic insights into the wetting mechanism,originating from the weakened adsorption capacity of the(111)surface for water molecules with the increasing lattice constant.展开更多
Since the pioneer work of Keller and Bhasin on the oxidative coupling of methane, many catalyst systems, mostly based on the oxides or complex oxides of alkali metals, alkali earth metals and rare earth metals, have b...Since the pioneer work of Keller and Bhasin on the oxidative coupling of methane, many catalyst systems, mostly based on the oxides or complex oxides of alkali metals, alkali earth metals and rare earth metals, have been developed. In some studies, halides, especially chlorides and bromides, have been added to these oxides in order to improve the catalvtic activitv and selectivity. howevek of展开更多
Psoriasis is an inflammatory skin disease that is intricately linked to oxidative stress.Antioxidation and inhibition of abnormal proliferation of keratinocytes are pivotal strategies for psoriasis.Delivering drugs wi...Psoriasis is an inflammatory skin disease that is intricately linked to oxidative stress.Antioxidation and inhibition of abnormal proliferation of keratinocytes are pivotal strategies for psoriasis.Delivering drugs with these effects to the site of skin lesions is a challenge that needs to be solved.Herein,we reported a nanotransdermal delivery system composed of all-trans retinoic acid(TRA),triphenylphosphine(TPP)-modified cerium oxide(CeO2)nanoparticles,flexible nanoliposomes and gels(TCeO_(2)-TRA-FNL-Gel).The results revealed that TCeO_(2)synthesized by the anti-micelle method,with a size of approximately 5 nm,possessed excellent mitochondrial targeting ability and valence conversion capability related to scavenging reactive oxygen species(ROS).TCeO_(2)-TRA-FNL prepared by the film dispersion method,with a size of approximately 70 nm,showed high drug encapsulation efficiency(>96%).TCeO_(2)-TRA-FNL-Gel further showed sustained drug release behaviors,great transdermal permeation ability,and greater skin retention than the free TRA.The results of in vitro EGF-induced and H2O2-induced models suggested that TCeO_(2)-TRA-FNL effectively reduced the level of inflammation and alleviated oxidative stress in HaCat cells.The results of in vivo imiquimod(IMQ)-induced model indicated that TCeO_(2)-TRA-FNL-Gel could greatly alleviate the psoriasis symptoms.In summary,the transdermal drug delivery system designed in this study has shown excellent therapeutic effects on psoriasis and is prospective for the safe and accurate therapy of psoriasis.展开更多
基金supported by Graduate Innovation Project of Shanxi Normal University(Grant No.2021Y443).
文摘Enhanced UV-B radiation represents a major environmental factor impacting global cereal production.Researchers have explored various approaches to reduce the detrimental impact of UV-B radiation on crops.Recently,engineered nanoparticles,particularly cerium oxide nanoparticles(CeO_(2)-NPs),have attracted widespread interest for their ability to boost plant tolerance to a range of abiotic stresses.This study investigates how CeO_(2)-NPs application affects the morphology,physiology,biochemistry,and transcriptomics profiles of wheat seedling roots subjected to enhanced UV-B stress.The findings demonstrate that CeO_(2)-NPs notably promoted root length,fresh and dry weights,and root activity(p<0.05)under enhanced UV-B stress.CeO_(2)-NP treatment reduced the content of hydrogen peroxide<(H_(2)O_(2))and malondialdehyde(MDA)in wheat,alleviating oxidative damage in seedling roots and partially restoring the root phenotype.Under non-UV-B stress conditions,CeO_(2)-NP treatment triggered the difference of 237 transcripts in plants relative to the control group.Under enhanced UV-B stress,CeO_(2)-NP treatment exhibited differentially expressed genes(DEGs)linked to the antioxidant defense mechanism responsible for reactive oxygen species(ROS)scavenging,compared to the non-nanoparticle control.This suggests that ROS scavenging may be a key mechanism by which CeO_(2)-NPs enhance wheat resistance to enhanced UV-B radiation.This study elucidates a potential molecular mechanism through which CeO_(2)nanoparticles may enhance wheat tolerance to UV-B stress.
基金Project supported by the National Key Research and Development Program(2021YFB3501101)Beijing Nova Program(20220484827)+2 种基金National Natural Science Foundation of China(52304370)Central Government Guidance Local Science and Technology Development Fund Project of Hebei Province(236Z4102G)Natural Science Foundation of Hebei Province(E2022103012)。
文摘Rare earth carbonates are essential precursors for the synthesis of oxide materials.In this study,we utilized in situ monitoring equipment to explore the alterations in the crystallization during the coprecipitation synthesis of cerium carbonate.By controlling the crystallization pathway and in the absence of any te mplating agents,we successfully synthesized a unique sphe rical self-assembled cerium oxide particle(Ceria-S).The Ceria-S exhibits excellent polishing performance.The crystallization process of cerium carbonate at 50℃persists for roughly 50 min.During the initial stages of crystallization from 0 to t_(3),the precipitated particles are amorphous.This is followed by a plateau phase of crystal growth from t_(3)to t_(5).Subsequently,during the burst crystallization phase from t_(5)to t_(6),Ce_(2)(CO_(3))_(3)·6H_(2)O and Ce_(2)O(CO_(3))_(2)·nH2O are formed,exhibiting a rod-like crystal morphology.By rapidly drying the precipitated particles at 60℃for 10 min and calcining,Ceria-S is obtained.The Ceria-S,with an average diameter of 180 nm,is assembled from primary cerium oxide nanoparticles of approximately 15 nm.Owing to the self-assembly structure of cerium oxide spherical nanoparticles,they exhibit a significantly larger specific surface area,resulting in an elevated concentration of Ce^(3+)as high as 35.5%.The Ceria-S exhibits a polishing removal rate of 420 nm/min,effectively decreasing the surface roughness(S_(a))of K9 glass from 1.605 to 0.404 nm.
基金Project supported by the National Natural Science Foundation of China(52064011,52274331)Science and Technology Planning Project of Guizhou(Qian Ke He Ji Chu ZK[2021]258,Qian Ke He Chengguo[2022]089,Qian Ke He Chengguo[2021]086)。
文摘It is challenging to assess the mechanism responsible for the nucleation of inclusions in metals at high temperatures.The present work therefore systematically investigates the nucleation of cerium oxide inclusions according to classical nucleation theory and a two-step nucleation mechanism.The nucleation rates and nucleation radii of these inclusions are obtained,and the results demonstrate a considerable difference between theoretical and experimental values.On the basis of a two-step nucleation mechanism,(CeO_(2))_(n) and(Ce_(2)O_(3))_(n)(n=1-6)clusters were constructed and the thermodynamic properties of both these clusters and of cerium oxide nanoparticles were analyzed.In addition,the entropies and heat capacity changes of cerium oxides were determined using first principles calculations and are found to be consistent with literature data.The present data indicate that the cerium oxide inclusion nucleation pathway can be summarized as[Ce]+[O]→(CeO_(2))n/(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(2)→core(Ce_(2)O_(3)crystal)-shell((Ce_(2)O_(3))_(2) cluster)nanoparticles→(Ce_(2)O_(3))bulk.
基金the Science and Technology Development Planning Project of Jilin Province (20040125, 20060504, 20070402)the Scien-tific Research Planning Project of the Education Department of Jilin Province (2005109, 2006YJT05)the Scientific Research Project of En-vironment Protection Bureau of Jilin Province(2006-24)
文摘Electrospinning technique was used to fabricate PVP/Ce（NO3）3 composite microfibers. Different morphological CeO2 nanofibers were obtained by calcination of the PVP/Ce（NO3）3 composite microfibers and were characterized by scanning electron microscopy （SEM）, Transmission electron microscopy （TEM）, X-ray diffraction （XRD）, thermal gravimetric and differential thermal analysis （TG-DTA）, and （FTIR）. SEM micrographs indicated that the surface of the composite fibers was smooth and became coarse with the increase of calcination temperatures. The diameters of CeO2 hollow nanofibers （300 nm at 600 ℃ and 600 nm at 800 ℃ ） were smaller than those of PVP/Ce（NO3）3 composite fibers （1-2 um ）. CeO2 hollow nanofibers were obtained at 600 ℃ and CeO2 hollow and porous nanofibers formed by nanoparti- cles were obtained at 800 ℃. The length of the CeO2 hollow nanofibers was greater than 50 um. XRD analysis revealed that the composite microfibers were amorphous in structure and CeO2 nanofibers were cubic in structure with space group O^5H - FM3m when calcination tem- peratures were 600-800 ℃. TG-DTA and FTIR revealed that the formation of CeO2 nanofibers was largely influenced by the calcination temperatures. Possible formation mechanism of CeO2 hollow nanofibers was proposed.
基金supported by Natural Science Foundation of Hebei Province(E2015205159)High Level Talents Foundation in Hebei Province(C201400327)Natural Science Foundation of Hebei Education Department(ZD2014045)
文摘Nanostructured cerium oxide （CeO2） commonly known as nanoceria is a rare earth metal oxide, which plays a technologically important role due to its versatile applications as antomobile exhaust catalysts, oxide ion conductors in solid oxide fuel cells, electrode materials for gas sensors, ultraviolet absorbents and glass-polishing materials. However, nanoceria has little or weak luminescence, and therefore its uses in high-performance luminescent devices and biomedical areas are limited. In this review, we present the recent advances of nanoceria in the aspects of synthesis, luminescence and biomedical studies. The CeO2 nanoparticles can bc synthesized by solution-based methods including co-precipitation, hydrothemlal, microemulsion process, sol-gel techniques, combustion reaction and so on. Achieving controlled morphologies and enhanced luminescence efficiency of nanoceria particles arc quite essential for its potential energyand environment-related applications. Additionally, a new fiontier for nanoccria particles in biomedical research has also been opened, which involves low toxicity, retinopathy, biosensors and cancer therapy aspects. Finally, the summary and outlook on the challenges and perspectives of the nanoceria particles are proposed.
基金Project supported by the Indian Society of Pedodontics and Preventive Dentistry (ISPPD/2022/111)。
文摘Nanotechnology deals with particles ranging from 1 to 100 nm in size called as nanoparticles.These nano particles exhibit unique properties which find an application in many industries and medical fields.A growing body of evidence points out the newer developing technologies adopted in the field of medicine in terms of target therapies,imaging systems,drug deliveries,etc.is through the incorporation of nanoparticles.Cerium oxide nanoparticles have gained attention in the last decade due to exceptional properties such as redox activity,biofilm inhibition,antibacterial activity,anti-inflammatory activity,etc.The method of synthesis of cerium oxide nanoparticles plays a pivotal role in its application.It exhibits redox properties and catalytic activity and thus has found its use in biomedical applications.Nanoparticles are incorporated into dental materials such as restorative cements/sealants,adhesives,and denture systems to improve their properties.Among the various metal oxide nanoparticles,ce rium oxide nanoparticles(CeO_(2)NPs)are known to exhibit lower toxicity to mammalian cells and possess unique antibacterial mechanism.In addition,they exhibit potent properties such as antitumor,antiinflammatory,antibacterial activities,and functions as an immunosensor.CeO_(2)NPs have excellent scavenging properties for reactive oxygen species,which is why they are being considered for therapeutic purposes.In this review,various methods of synthesis of CeO_(2)NPs are discussed.Several factors that determine the particle size and morphology of these materials are important for biomedical and dental applications.Emphasis is given to preparation methods and variables such as calcination temperature,which have a profound effect on particle size and morphology.This article also presents various applications of CeO_(2)NPs in the biomedical and dental fields.
文摘A new method for the separation and detection of trace metal impurities in cerium oxide (CeO_2) using HPLC combined with electrothermal vaporization (ETV)-ICP-AES was developed. This combination links the high separation power of HPLC and high sensitivity of ETV-ICP-AES. The 2-ethylhexyl hydrogen 2-ethylhexylphosphate (P_(507)) resin was used as stationary phase for the separation of metallic impurities in order to eliminate severe spectral interferences of the matrix. The dilute nitric acid was adopted as mobile phase for eluting Cu, Mn, Ni and La. The separation process can be accomplished in about 30 min. After concentrating the eluate by evaporation, the trace impurities were determined by using ETV-ICP-AES with the addition of 6% PTFE slurry as chemical modifier. The proposed method was applied to the analysis of CeO_2 with satisfactory recoveries.
文摘Nano cerium oxide films were applied on AA7020-T6 aluminum alloy and the effects of acetic acid concentration on the microstructure and electrochemical properties of the coated samples were investigated by using scanning electron microscopy （SEM）, X-ray diffraction （XRD）, and potentiodynamic polarization methods. It has been found that by increasing the acetic acid/CeCl3·7H2O molar ratio, high uniform and crack-free films with well-developed grains were obtained and grain sizes of the films decreased. Elimination of cracks and decreasing grain size of the nano cerium oxide films caused corrosion resistance to increase.
文摘Cerium oxide nanoparticles(CNPs)possess a great potential as therapeutic agents due to their ability to self-regenerate by reversibly switching between two valences+3 and+4.This article reviews recent articles dealing with in vivo studies of CNPs towards Alzheimer’s disease,obesity,liver inflammation,cancer,sepsis,amyotrophic lateral sclerosis,acute kidney injury,radiation-induced tissue damage,hepatic ischemia reperfusion injury,retinal diseases and constipation.In vivo anti-cancer studies revealed the effectiveness of CNPs to reduce tumor growth and angiogenesis in melanoma,ovarian,breast and retinoblastoma cancer cell-induced mice,with their conjugation with folic acid,doxorubicin,CPM,or CXC receptor-4 antagonist ligand eliciting higher efficiency.After conjugation with triphenylphosphonium or magnetite nanoparticles,CNPs were shown to combat Alzheimer’s disease by reducing amyloid-β,glial fibrillary acidic protein,inflammatory and oxidative stress markers in mice.By improving muscle function and longevity,the citrate/EDTA-stabilized CNPs could ameliorate amyotrophic lateral sclerosis.Also,they could effectively reduce obesity in mice by scavenging ROS and reducing adipogenesis,triglyceride synthesis,GAPDH enzyme activity,leptin and insulin levels.In CCl4-induced rats,stress signaling pathways due to inflammatory cytokines,liver enzymes,oxidative and endoplasmic reticulum messengers could be attenuated by CNPs.Commercial CNPs showed protective effects on rats with hepatic ischemia reperfusion and peritonitis-induced hepatic/cardiac injuries by decreasing oxidative stress and hepatic/cardiac inflammation.The same CNPs could improve kidney function by diminishing renal superoxide,hyperglycemia and tubular damage in peritonitis-induced acute kidney injury in rats.Radiation-induced lung and testicular tissue damage could be alleviated in mice,with the former showing improvement in pulmonary distress and bronchoconstriction and the latter exhibiting restoration in spermatogenesis rate and spermatid/spermatocyte number.Through enhancement of gastrointestinal motility,the CNPs could alleviate constipation in both young and old rats.They could also protect rat from light-induced retinal damage by slowing down neurodegenerative process and microglial activation.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest,Ministry of Agriculture of the People’s Republic of China(201403066)Natural Science Foundation of Hainan Province(20155198)the Fundamental Research Funds for Rubber Research Institute,Chinese Academy of Tropical Agricultural Science(1630022014014)
文摘Variable masses of nano cerium oxide (CeO2) were added into nano silica (SiO2) to prepare the well-dispersed SiO2-CeO2 suspension (SiO2-CeO2), cetyltrimethyl ammonium bromide (CTAB) was used to adjust the compatibility of SiO2-CeO2 with rubber matrix, then SiO2-CeO2 modified by CTAB and curing formulas were mixed with fresh natural rubber (NR) latex to prepare NR/SiO2-CeO2 nanocomposites that contained 0–10 parts of CeO2 by a new emulsion compounding method. The morphologies, cure characteristics, mechanical properties and thermal-oxidative stability of NR/SiO2-CeO2 nanocomposites were investigated. The re-sults revealed that the presence of CeO2 in NR/SiO2-CeO2nanocomposites was favorable for enhancing the interaction between NR matrix and fillers, helped to get smaller SiO2-CeO2 particles with narrower particle size distribution, further improved the crosslink densities and mechanical properties of NR/SiO2-CeO2 nanocomposites vulcanizates. Meanwhile, the addition of CeO2 increased the active energy at least 4.66%, obviously improved the thermal-oxidative aging-inhibiting properties of NR/SiO2-CeO2 nanocomposites. Additionally, nanocomposites containing CeO2 promotedTg shift to high temperature direction, causing the nanocomposites featured higher tanδ at 0 oC and lower tanδ at 60 oC and exhibited comparable wet grip and lower rolling resistance when NR/SiO2-CeO2nano-composites were used in tire tread compound.
文摘Characteristics of carbon deposition of CH 4 and C 2H 4 decomposition over supported Ni and Ni Ce catalysts were studied by using a pulse reaction as well as BET, TPR, XPS and hydrogen chemisorption techniques. It is found that there is a metal semiconductor interaction (MScI) in the Ni Ce catalyst, and the effect of MScI on the carbon deposition of CH 4 decomposition is opposite to that of C 2H 4. A novel model of carbon deposition of CH 4 or C 2H 4 decomposition was proposed.
文摘During the previous years, with the emerging of nanotechnology, the enormous capabilities of nanoparticles have drawn great attention from researchers in terms of their potentials in various aspects of pharmacology. Cerium oxide nanoparticles（nanoceria）, considered as one of the most widely used nanomaterials, due to its tempting catalytic antioxidant properties, show a promising potential in diverse disorders, such as cerebral ischemic stroke（CIS）, cancer, neurodegenerative and inflammatory diseases. Overwhelming generation of reactive oxygen species（ROS） and reactive nitrogen species（RNS） during cerebral ischemia and reperfusion periods is known to aggravate brain damage via sophisticated cellular and molecular mechanisms, and therefore exploration of the antioxidant capacities of nanoceria becomes a new approach in reducing cerebral ischemic injury. Furthermore, utilizing nanoceria as a drug carrier might display the propensity to overcome limitations or inefficacy of other conceivable neuroprotectants and exhibit synergistic effects. In this review, we emphasize on the principle features of nanoceria and current researches concerning nanoceria as a potential therapeutic agent or carrier in improving the prognosis of CIS.
基金Project supported by the Inner Mongolia Science & Technology Innovation Leading Award Fund Project (20081717)
文摘The large particle cerium oxide was prepared using oxalic acid as precipitation agent. The effects of preparation conditions on the particle size of cerium oxide were discussed. The results showed that the particle size of cerium oxide could be controlled effectively by the temperature,acidity of the solution,aging time,etc. The optimized preparation process of large particle cerium oxide was obtained. The cerium oxide with size between 50 μm to 150 μm was prepared by the process. Moreover,the cerium oxide particles were dispersed uniformly.
基金financially supported by the National Natural Science Foundation of China (No.51904069)the Natural Science Foundation of Hebei Province of China (No.E2019501085)+2 种基金the Colleges and Universities in Hebei Province Science and Technology Research Youth Fund (No.QN2019312)the Fundamental Research Funds for the Central Universities (No.N172303012)the National Science and Technology Support Program (No.2012BAE01B02)
文摘Ultrafine rare-earth oxides(REOs) are widely applied in all fields of daily life,but the conventional preparation methods are limited by a long procedure,low efficiency and severe environmental pollution.Our team has independently developed a jet pyrolysis reactor for the preparation of ultrafine cerium oxides,and this process has theoretical significance and practical application values.In this study,gas-solid pyrolysis reactions inside the jet-flow pyrolysis reactor were numerically simulated.We performed a coupling computation of the combustion,phase transformation and gas-solid reaction on Fluent and userdefined functions.We characterized the flows of different phases as well as the compositions and distributive laws of the reactants/products in the reactor.The gas-phase inlet velocity and dynamic pressure/additional pressure were related by a quadratic function.The velocity at the throat inlet changed the most,and the outlet velocity was very stable.The CeO2 concentrations were obviously stratified.This study enriches theories of jet-flow pyrolysis and theoretically underlies the optimization and popularization of self-developed pyrolysis reactors.
基金supported by the Iranian Nanotechnology and Nanoscience Organization.
文摘One of the main problems of stainless steel is its poor pitting corrosion resistance in the aggressive environment containing Cl-, such as seawater. In this paper we investigated the corrosion behavior of the 316 stainless steel coated by cerium oxide nanocoating prepared by sol-gel process. Potentiodynamic polarization and electrochemical impedance spectroscopy （EIS） were used to study the corrosion behavior of cerium oxide nanocoatings in 3.5% NaCl solution. The microstructure of the cerium oxide was examined by scanning electron microscopy （SEM） and the formed phases was identified by X-ray diffraction （XRD）. The pitting corrosion resistance of the cerium oxide nanocoating was found to be improved after heat treatment of the cerium oxide nanocoating at 300℃ for 30 min.
基金financially supported by Funding of Jiangsu Educational Committee (No. 19KJB430042)。
文摘In general, inorganic filler/polyurethane elastomer(PUE) composites possess favorable properties, such as modulus, chemical resistance, and heat stability, are promising for broadening the application area of polyurethanes(PU). For the experiments, a series of cerium oxide(CeO_(2))/PUE composites were prepared with different sizes and appearance of CeO_(2), and different mixing methods as well. CeO_(2) particles with different sizes were added into PUs during the formation of urethane linkage and the chain-extend process, respectively. The morphology along with mechanical properties, thermal properties of the composites were studied. The results suggest that the size of CeO_(2) and mixing methods influence the microstructure of PUs which has profound effect on properties of these composites. The composites tend to form more quantity of hard domains(HDs) with small size when CeO_(2) particles were added before the formation of urethane linkage, whereas Ce O2 particles increase the size of HDs when added with chain extender into PU prepolymer.
基金Project supported by the National Key Basic Research Program(NKBRP20047CCA03900)National Natural Science Foundation of China(2056601)
文摘Study was made on the effect of surface modification on the behaviors of cerium oxide nanopowders.A surfactant-sodium dodecyl sulfate（C12H25SO4Na）was used to modify the surface of CeO2 powder particles.The unmodified and modified CeO2 powders were characterized by using a powder comprehensive characteristic tester,laser particle size analyzer,specific surface area tester,X-ray diffraction tester,and a scanning electron microscope.The testing and analysis results showed that C12H25SO4Na surface modification might increase the flowability and dispersity,and decrease the specific surface area and agglomeration of CeO2 powders.The mechanism of the surface modification of CeO2 powder particles was also discussed.
基金financially supported by the National Natural Science Foundation of China(Nos.51901062 and U1908220)the Natural Science Foundation of Zhejiang Province(No.LR18E010001)+1 种基金the Key R&D Project of Zhejiang Province(Nos.2019C01121 and 2021C01023)the LiaoNing Revitalization Talents Program(No.XLYC1807177)。
文摘Cerium oxide possesses intrinsic hydrophobic properties ascribed to the unique electronic structure.However,the relationship between the crystal structure and hydrophobicity of cerium oxide has not been systematically studied.Herein,it is experimentally and theoretically demonstrated that the water contact angle(105.9°)of the(111)surface is higher than that(91.7°)of the(220)surface,associated with the lower surface free energy(28.44 mN/m)of(111)surface than that(38.48 mN/m)of(220)surface.Furthermore,cerium oxide films with(111)-terminated surface are annealed at 300℃ and 600℃ for1 h,respectively.The lattice constant increases(5.4594Å<5.4613Å<5.4670Å)with decreasing the annealing temperature(600℃>300℃>the as-deposited),leading to the increased water contact angle(96.7°<96.8°<99.0°).The First-principles calculation provides microscopic insights into the wetting mechanism,originating from the weakened adsorption capacity of the(111)surface for water molecules with the increasing lattice constant.
文摘Since the pioneer work of Keller and Bhasin on the oxidative coupling of methane, many catalyst systems, mostly based on the oxides or complex oxides of alkali metals, alkali earth metals and rare earth metals, have been developed. In some studies, halides, especially chlorides and bromides, have been added to these oxides in order to improve the catalvtic activitv and selectivity. howevek of
基金supported by Zhejiang Provincial Natural Science Foundation of China under Grant No.LYY21H300001Zhejiang Medical and Health Science and Technology project under Grant No.2021KY906Hangzhou Medical Key Discipline Construction Project under Grant No.[2021]21–39
文摘Psoriasis is an inflammatory skin disease that is intricately linked to oxidative stress.Antioxidation and inhibition of abnormal proliferation of keratinocytes are pivotal strategies for psoriasis.Delivering drugs with these effects to the site of skin lesions is a challenge that needs to be solved.Herein,we reported a nanotransdermal delivery system composed of all-trans retinoic acid(TRA),triphenylphosphine(TPP)-modified cerium oxide(CeO2)nanoparticles,flexible nanoliposomes and gels(TCeO_(2)-TRA-FNL-Gel).The results revealed that TCeO_(2)synthesized by the anti-micelle method,with a size of approximately 5 nm,possessed excellent mitochondrial targeting ability and valence conversion capability related to scavenging reactive oxygen species(ROS).TCeO_(2)-TRA-FNL prepared by the film dispersion method,with a size of approximately 70 nm,showed high drug encapsulation efficiency(>96%).TCeO_(2)-TRA-FNL-Gel further showed sustained drug release behaviors,great transdermal permeation ability,and greater skin retention than the free TRA.The results of in vitro EGF-induced and H2O2-induced models suggested that TCeO_(2)-TRA-FNL effectively reduced the level of inflammation and alleviated oxidative stress in HaCat cells.The results of in vivo imiquimod(IMQ)-induced model indicated that TCeO_(2)-TRA-FNL-Gel could greatly alleviate the psoriasis symptoms.In summary,the transdermal drug delivery system designed in this study has shown excellent therapeutic effects on psoriasis and is prospective for the safe and accurate therapy of psoriasis.
