Since the discovery of enzyme-like activity of Fe3O4 nanoparticles in 2007,nanozymes are becoming the promising substitutes for natural enzymes due to their advantages of high catalytic activity,low cost,mild reaction...Since the discovery of enzyme-like activity of Fe3O4 nanoparticles in 2007,nanozymes are becoming the promising substitutes for natural enzymes due to their advantages of high catalytic activity,low cost,mild reaction conditions,good stability,and suitable for large-scale production.Recently,with the cross fusion of nanomedicine and nanocatalysis,nanozyme-based theranostic strategies attract great attention,since the enzymatic reactions can be triggered in the tumor microenvironment to achieve good curative effect with substrate specificity and low side effects.Thus,various nanozymes have been developed and used for tumor therapy.In this review,more than 270 research articles are discussed systematically to present progress in the past five years.First,the discovery and development of nanozymes are summarized.Second,classification and catalytic mechanism of nanozymes are discussed.Third,activity prediction and rational design of nanozymes are focused by highlighting the methods of density functional theory,machine learning,biomimetic and chemical design.Then,synergistic theranostic strategy of nanozymes are introduced.Finally,current challenges and future prospects of nanozymes used for tumor theranostic are outlined,including selectivity,biosafety,repeatability and stability,in-depth catalytic mechanism,predicting and evaluating activities.展开更多
The cathode materials LiMn2O4 and rare earth elements La-doped or La and F dual-doped spinel lithium manganese oxides.were synthesized by the citric acid-assisted sol-gel method. The synthesized samples were investiga...The cathode materials LiMn2O4 and rare earth elements La-doped or La and F dual-doped spinel lithium manganese oxides.were synthesized by the citric acid-assisted sol-gel method. The synthesized samples were investigated by differential thermal analysis (DTA) and thermogravimetry (TG) measurements, X-ray diffraction (XRD), scanning electronic microscope (SEM), cyclic voltammetry (CV), and charge-discharge test. XRD data shows that all the samples exhibit the same pure spinel phase, and the LiLa0.01Mn1.99O3.99F0.01 and LiLao.olMnl.9904 samples have smaller lattice parameters and unit cell volume than LiMn2O4. SEM indicates that LiLa0.01Mn1.99O3.99F0.01 has a slightly smaller particle size and a more regular morphology structure with narrow size distribution. The charge-discharge test reveals that the initial capacities of LiMn2O4, LiLa0.01Mn1.99O4, and LiLa0.01Mn1.99O3.99F0.01 are 129.9, 122.8, and 126.4 mAh·g^-1, and the capacity losses of the initial values after 50 cycles are 14.5%, 7.6%, and 8.0%, respectively The CVs show that the La and F dual-doped spinel displays a better reversibility than LiMn2O4.展开更多
Low larval survival,poor settlement,and abnormal metamorphosis are major problems in seed production of donkey-ear abalone Haliotis asinina.We examined the effects of chemical cues including epinephrine,nor-epinephrin...Low larval survival,poor settlement,and abnormal metamorphosis are major problems in seed production of donkey-ear abalone Haliotis asinina.We examined the effects of chemical cues including epinephrine,nor-epinephrine,and serotonin on larval survival,settlement,and metamorphosis in order to determine the possibility of using these chemicals to induce the problems.The results show that epinephrine could enhance metamorphosis rate at 10-6 mol/L only but higher concentrations(10-3-10-4 mol/L);and nor-epinephrine could inhibit the performance significantly,and serotonin could increase significantly the performance at a wide-range concentration(10-3-10-6 mol/L).Treatment with serotonin at 10-5 mol/L for 72 hours resulted in the highest settlement rate(42.2%) and survival rate(49.3%),while at 10-4 mol/L for 72 hours resulted in the highest metamorphosis rate(38.8%).Therefore,serotonin may be used as a fast metamorphosis inducer in abalone culture.展开更多
To improve the cycle performance of eco-friendly and cost-effective spinel LiMn2O4 as the Li secondary batteries, the Th-doped LiThxMn1-xO4 spinel powers were synthesized by solid-state method. The starting materials,...To improve the cycle performance of eco-friendly and cost-effective spinel LiMn2O4 as the Li secondary batteries, the Th-doped LiThxMn1-xO4 spinel powers were synthesized by solid-state method. The starting materials, Li2CO3, MnO2 and Th(NO3)4·4H2O, were mixed uniformly using a traditional ball milling, which resulted in a uniform particle size distribution in the mixed powers. Tests of X-ray diffraction, SEM, impedance spectra and charge-discharge were carried out for LiThxMn1-xO4 cathode materials. Results show that the synthesized LiTh0.01Mn1.99O4 material exhibits standard spinel structure, regular particle morphology and excellent property of charge-discharge for big current. The capacity retention of the material modified by doping Th is more than 85.1% of the first discharge specific capacity of 111.5 mAh·g-1 after 20 cycles at the current rate 1C, while the pristine LiMn2O4 is only 57% of the first discharge specific capacity of 110.2 mAh·g-1 after the same cycles at the same current rate.展开更多
In the search for improved materials for rechargeable lithium batteries, LiFePO4 offers interesting possibilities because of its low raw materials cost, environmental friendliness and safety. The main drawback with us...In the search for improved materials for rechargeable lithium batteries, LiFePO4 offers interesting possibilities because of its low raw materials cost, environmental friendliness and safety. The main drawback with using the material is its poor electronic conductivity and this limitation has to be overcome. Here Al-doped LiFePO4/C composite cathode materials were prepared by a polymer-network synthesis technique. Testing of X-ray diffraction, charge-discharge, and cyclic voltammetry were carried out for its performance. Results show that Al-doped LiFePO4/C composite cathode materials have a high initial capacity, good cycle stability and excellent low temperature performance. The electrical conductivity of LiFePO4 material can be obviously improved by doping Al. The better electrochemical performances of Al-doped LiFePO4/C composite cathode materials have a connection with its conductivity.展开更多
1.Introduction Carbon materials have been widely investigated as the anode materials for Na+storage due to their moderate capacity,good stability,and low cost.The Na+storage mechanisms of carbon are generally classifi...1.Introduction Carbon materials have been widely investigated as the anode materials for Na+storage due to their moderate capacity,good stability,and low cost.The Na+storage mechanisms of carbon are generally classified into diffusion-controlled interlayer insertion/desertion and capacitive-controlled surface adsorption/desorption[1].展开更多
Magnesium(Mg) alloys, as the lightest metal engineering materials, have broad application prospects.However, the strength and ductility of traditional Mg alloys are still relativity low and difficult to improve simult...Magnesium(Mg) alloys, as the lightest metal engineering materials, have broad application prospects.However, the strength and ductility of traditional Mg alloys are still relativity low and difficult to improve simultaneously.Refining grain size via the deformation process based on the grain boundary strengthening and the transition of deformation mechanisms is one of the feasible strategies to prepare Mg alloys with high strength and high ductility.In this review, the effects of grain size on the strength and ductility of Mg alloys are summarized, and fine-grained Mg alloys with high strength and high ductility developed by various severe plastic deformation technologies and improved traditional deformation technologies are introduced.Although some achievements have been made, the effects of grain size on various Mg alloys are rarely discussed systematically and some key mechanisms are unclear or lack direct microscopic evidence.This review can be used as a reference for further development of high-performance fine-grained Mg alloys.展开更多
Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallizatio...Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallization(DRX)fraction and coarsened DRX grains,which further suggests weakened basal fiber texture for the studied alloy.This is mainly due to the rising temperature from massive deformation heat when hot-extrusion.As a result,greater ER corresponds to a decreased strength but improved ductility.Finally,transmission electron microscopy(TEM)observations reveal that the dominant intermetallic phase,Mg_(3)Sm,is metastable,and it will transform into Mg_(41)Sm_(5)during extrusion with high-ER.This transformation leads to the accumulation of surplus Sm and Zn atoms,which induces the precipitation of Sm Zn_(3)phase at the surface of Mg_(41)Sm_(5)matrix.展开更多
Ionic liquids(ILs) are attracting much attention in various fields of chemical synthesis, electrochemical applications, liquid-liquid extractions, as well as biotransformations. Among those fields, the application o...Ionic liquids(ILs) are attracting much attention in various fields of chemical synthesis, electrochemical applications, liquid-liquid extractions, as well as biotransformations. Among those fields, the application of ILs as the potential green solvent for a wide variety of synthetic processes is an area of intense researches. High yield, high selectivity, and good catalytic charac-teristics have usually been achieved. After the isolation of products, ILs can usually be recovered and recycled many times by simple treating procedures, such as, filtration, extraction, and dryness.展开更多
A new polymer, poly-silicon-ferric with oxidization (PSFN) coagulant was produced by adding KMnO4 and stabilizer M to poly-silicon-ferric (PSF) coagulant. The micro properties of PSFN was investigated with optical mic...A new polymer, poly-silicon-ferric with oxidization (PSFN) coagulant was produced by adding KMnO4 and stabilizer M to poly-silicon-ferric (PSF) coagulant. The micro properties of PSFN was investigated with optical microscope, transmission electron microscope(TEM), ultraviolet/visible absorption(UVA) scanning, infrared(IR) spectrometer and oxidation-reduction potential (ORP) meter respectively, compared to that of PSF. The coagulation behavior by PSFN was investigated compared to that by PSF. The results show that the micro properties of PSF have been changed greatly due to the addition of KMnO4, and there exists KMnO4 unattached in PSFN. A kind of tetrahedron structure somewhat like the connection of Si-O-Si bonds may be formed by the complexation of Mn (maybe in various valence) with PSF. PSFN has lower turbidity removal than PSF at lower dose and achieves the same when the dose reaches a definite amount, while the removal of UV254 by PSFN is higher than that by PSF almost over entire dose range with the largest difference of about 17%. PSFN has more oxidization function at acidic condition than that at basic condition, and gives stronger ability of application for treating various waters than that by PSF.展开更多
The development of lithium-sulfur batteries(LSBs)is restricted by their poor cycle stability and rate performance due to the low conductivity of sulfur and severe shuttle effect.Herein,an N,O co-doped graphene layered...The development of lithium-sulfur batteries(LSBs)is restricted by their poor cycle stability and rate performance due to the low conductivity of sulfur and severe shuttle effect.Herein,an N,O co-doped graphene layered block(NOGB)with many dents on the graphene sheets is designed as effective sulfur host for high-performance LSB s.The sulfur platelets are physically confined into the dents and closely contacted with the graphene scaffold,ensuring structural stability and high conductivity.The highly doped N and O atoms can prevent the shuttle effect of sulfur species by strong chemical adsorption.Moreover,the micropores on the graphene sheets enable fast Li^+transport through the blocks.As a result,the obtained NOGB/S composite with 76 wt%sulfur content shows a high capacity of 1413 mAh g^-1 at 0.1 C,good rate performance of 433 mAh g^-1 at 10 C,and remarkable stability with 526 mAh g^-1 at after 1000 cycles at 1 C(average decay rate:0.038%per cycle).Our design provides a comprehensive route for simultaneously improving the conductivity,ion transport kinetics,and preventing the shuttle effect in LSBs.展开更多
The acrylonitrile-butadiene-styrene (ABS) surface was etched by dipping it into chromic acid-sulfuric acid containing a trace amount of palladium. The surface roughness, activity, and valence bond were characterized...The acrylonitrile-butadiene-styrene (ABS) surface was etched by dipping it into chromic acid-sulfuric acid containing a trace amount of palladium. The surface roughness, activity, and valence bond were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The results showed that with the increase of Pd concentration in the etching solution the ABS surface roughness reduced. The ratio of O to C increases and forms a large amount of O=C?O functional groups by dipping into Pd contained etching solution, thus the amount of colloids palladium adsorption increases. The carboxyl group acts as the ad- sorption site for the Pd/Sn catalyst.展开更多
Thin films of incompatible polymer blends can form a variety of structures during preparation and subsequent annealing process. For the polymer blend system consisting of polystyrene and poly(styrene-co-p-bromo-styr...Thin films of incompatible polymer blends can form a variety of structures during preparation and subsequent annealing process. For the polymer blend system consisting of polystyrene and poly(styrene-co-p-bromo-styrene), i.e., PS/PBrxS, its compatibility could be adjusted by varying the degree of bromination and the molecular weight of both components comprised. In this paper, surface chemical compositions of the cast and the annealing films were investigated by X-ray photoelectron spectroscopy (XPS) and contact angle measurement; meanwhile, surface topographical changes are followed by atomic force microscopy (AFM). In addition, substantial attention was paid to the effect of annealing on the morphologic variations induced by phase separation and/or dewetting of the thin film. Moreover, the influences of the molecular weight, Mw, as well as the brominated degree, x%, on the sample surface are explored systematically, and the corresponding observations are explained in virtue of the Flory-Huggins theory, along with the dewetting of the polymer thin film.展开更多
A new 4-chlorobenzoic acid bridge Co(Ⅱ ) complex [[Co2(2,2'-bpy)2(μ-L)e(L)2(μ-H2O)] (HL = 4-chlorobenzoic acid) has been obtained by hydrothermal synthesis, and X-ray single-crystal diffraction analysi...A new 4-chlorobenzoic acid bridge Co(Ⅱ ) complex [[Co2(2,2'-bpy)2(μ-L)e(L)2(μ-H2O)] (HL = 4-chlorobenzoic acid) has been obtained by hydrothermal synthesis, and X-ray single-crystal diffraction analysis shows that it crystallizes in the monoclinic system, space group C2/c with a = 22.537(5), b = 16.212(3), c = 15.306(3) A, β= 124.37(3)°, V= 4616.1(16)A3, Mr = 1070.45, Dc = 1.540 g/cm3, Z = 4, p = 1.012 mm-1, F(000) = 2176, the final R = 0.0338 and wR= 0.0810. The title complex is composed of dinuclear [Co2(2,2'-bpy)2(μ-L)2(L)2(μ-HaO)] molecules. Each Co(Ⅱ ) atom is coordinated by two nitrogen atoms from one 2,2’-bipyridine ligand, three oxygen atoms from three 4-chlorobenzoic ions and another oxygen atom from one water molecule. The two Co(Ⅱ) atoms are connected by two 4-chlorobenzoic ions and one bridged water molecule. The dinuclear molecules are interlinked by hydrogen bond and π-π stacking interactions into a three-dimensional supramolecular network.展开更多
Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction press...Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction pressure and Al/Cr molar ratio on ethylene tetramerization were investigated in detail. Chromium was uniformly and firmly immobilized on the support and could not be leached off by methylaluminoxane. The supported catalyst, upon being activated with methylaluminoxane, exhibited catalytic activity of 1.70×107 g/(mol Cr·h) for ethylene tetramerization to form 1-octene at a reaction temperatures of 80 ℃, a pressure of 2.0 MPa and an Al/Cr molar ratio of 300. The supported catalyst presented a good tolerance to high temperature.展开更多
The effect of Gd content on the microstructure and tensile properties of as-cast Mg-Sm-Zn-Zr alloy has been systematically investigated.In the Mg-3Sm-0.5Zn-0.5Zr alloy, the intermetallic compounds with multiple morpho...The effect of Gd content on the microstructure and tensile properties of as-cast Mg-Sm-Zn-Zr alloy has been systematically investigated.In the Mg-3Sm-0.5Zn-0.5Zr alloy, the intermetallic compounds with multiple morphologies are identified as Mg_(3)Sm phase. In addition to Mg_(3)RE phase, Mg_(5)RE phase originated from Gd addition is observed in Gd-modified alloys. It should be noted that the lattice parameters of all the observed intermetallic compounds are significantly reduced by Zn segregation. The segregation behavior of Zn in Mg_(3)Sm phase is inhibited to some extent by Gd addition due to the electronegativity difference between Sm/Gd and Zn elements. In addition, the increased Gd content effectively leads to much more accumulation of solute atoms in front of the liquid-solid interface during solidification, which can prominently promote nucleation in liquid region and then refine grains. The tensile yield stress of the present alloys is thus improved with increasing Gd addition. Finally, Gd-modified alloys exhibit significantly age-hardening effect, which can be mainly attributed to the high-volume fraction and high density nano-scale precipitates.展开更多
Phototoxic treatments of pathogenic bacteria and fungi of trees induce oxidative damage that is preferable to toxic chemical treatment.Here,we used green methods to synthesize Chlorin e6 from chlorophyll a,which was e...Phototoxic treatments of pathogenic bacteria and fungi of trees induce oxidative damage that is preferable to toxic chemical treatment.Here,we used green methods to synthesize Chlorin e6 from chlorophyll a,which was extracted from crude silkworm excrement using concentrated(strong)alkali hydrolysis and acidification.The photosensitive bactericidal activities of the new chlorin were tested in vitro,and possible mechanisms of action are discussed.The results showed that Chlorin e6 can be lightactivated to have bactericidal activity against Escherichia coli,Bacillus subtilis and Fusarium oxysporum,but it had little bactericidal effect in the dark.This kind of chlorin compounds has great potential as a natural phototoxic antimicrobial compound to control harmful bacteria on the leaves in forestry systems.展开更多
SrLi_(2)Ti_(6)O_(14)(SLTO)coated with different amount of ZrO_(2)was successfully prepared.The as-obtained composites are stacked by a series of particles with a pure phase structure and a good crystallinity.Furthermo...SrLi_(2)Ti_(6)O_(14)(SLTO)coated with different amount of ZrO_(2)was successfully prepared.The as-obtained composites are stacked by a series of particles with a pure phase structure and a good crystallinity.Furthermore,ZrO_(2)coating not only enhances the structural stability of the materials but also facilitates the diffusion of lithium through the SEI film.As a result,the redox polarization was reduced,and the reversibility of the electrochemical reaction was enhanced.Particularly,SLTO-ZrO_(2)-2 sample delivers a high initial lithiation capacity of 283.6 mA h g^(-1),and the values maintain at 251.7,228.0,207.4,175.3,and 147.7 mA h g^(-1)at the current densities of 0.13,0.26,0.54,1.31,and 2.62 A g^(-1),respectively.Our experiment also confirmed that SLTO materials coated with ZrO_(2)are suitable for high power density applications,and the lithiation specific energy efficiency of SLTO-ZrO_(2)-2 is 200%as high as that of pure SLTO at a power density of 1257 W kg^(-1).展开更多
Nickel-base superalloys are materials of choice for manufacturing hot-section components in gas turbines due to their superior mechanical properties at high temperatures [1]. For maintaining and improving the properti...Nickel-base superalloys are materials of choice for manufacturing hot-section components in gas turbines due to their superior mechanical properties at high temperatures [1]. For maintaining and improving the properties, this kind of materials are often cast into single crystal form. Nevertheless, severe service conditions of high temperature and high pressure, often cause tip and platform damages.展开更多
Electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) techniques were used to detect stress corrosion cracking(SCC) on 40Cr steel specimens exposed to the acidified chloride solution at ambient. To...Electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) techniques were used to detect stress corrosion cracking(SCC) on 40Cr steel specimens exposed to the acidified chloride solution at ambient. To test these two techniques,slow strain rate tensile(SSRT) tests were performed with 40Cr specimen in the identical corrosive solution at room temperature. In impedance measurements,phase shifts in frequency range from 1 to 1 000 Hz show a clear difference between the stressed and non-stressed specimens,suggesting that stress corrosion cracks are detected by the impedance measurements. EN signals in the process of SCC were recorded and then analyzed by standard deviation(STD). On the other hand,the mechanical properties,such as maximum tensile strength(MTS) and fracture strain(FS) measured by the SSRT,decrease significantly when the specimens are exposed to the corrosive solution relative to that in an inert medium. The SSRT results are consistent with fractography of the tested specimens by scanning electron microscopy(SEM). Analysis of the fracture surface clearly shows intergranular attack,suggesting that stress corrosion cracks are formed.展开更多
基金S.G.acknowledges the financial support from the National Natural Science Foundation of China(NSFC 52272144,51972076)the Heilongjiang Provincial Natural Science Foundation of China(JQ2022E001)+4 种基金the Natural Science Foundation of Shandong Province(ZR2020ZD42)the Fundamental Research Funds for the Central Universities.H.D.acknowledges the financial support from the National Natural Science Foundation of China(NSFC 22205048)China Postdoctoral Science Foundation(2022M710931 and 2023T160154)Heilongjiang Postdoctoral Science Foundation(LBH-Z22010)G.Y.acknowledges the financial support from the National Science Foundation of Heilongjiang Education Department(324022075).
文摘Since the discovery of enzyme-like activity of Fe3O4 nanoparticles in 2007,nanozymes are becoming the promising substitutes for natural enzymes due to their advantages of high catalytic activity,low cost,mild reaction conditions,good stability,and suitable for large-scale production.Recently,with the cross fusion of nanomedicine and nanocatalysis,nanozyme-based theranostic strategies attract great attention,since the enzymatic reactions can be triggered in the tumor microenvironment to achieve good curative effect with substrate specificity and low side effects.Thus,various nanozymes have been developed and used for tumor therapy.In this review,more than 270 research articles are discussed systematically to present progress in the past five years.First,the discovery and development of nanozymes are summarized.Second,classification and catalytic mechanism of nanozymes are discussed.Third,activity prediction and rational design of nanozymes are focused by highlighting the methods of density functional theory,machine learning,biomimetic and chemical design.Then,synergistic theranostic strategy of nanozymes are introduced.Finally,current challenges and future prospects of nanozymes used for tumor theranostic are outlined,including selectivity,biosafety,repeatability and stability,in-depth catalytic mechanism,predicting and evaluating activities.
文摘The cathode materials LiMn2O4 and rare earth elements La-doped or La and F dual-doped spinel lithium manganese oxides.were synthesized by the citric acid-assisted sol-gel method. The synthesized samples were investigated by differential thermal analysis (DTA) and thermogravimetry (TG) measurements, X-ray diffraction (XRD), scanning electronic microscope (SEM), cyclic voltammetry (CV), and charge-discharge test. XRD data shows that all the samples exhibit the same pure spinel phase, and the LiLa0.01Mn1.99O3.99F0.01 and LiLao.olMnl.9904 samples have smaller lattice parameters and unit cell volume than LiMn2O4. SEM indicates that LiLa0.01Mn1.99O3.99F0.01 has a slightly smaller particle size and a more regular morphology structure with narrow size distribution. The charge-discharge test reveals that the initial capacities of LiMn2O4, LiLa0.01Mn1.99O4, and LiLa0.01Mn1.99O3.99F0.01 are 129.9, 122.8, and 126.4 mAh·g^-1, and the capacity losses of the initial values after 50 cycles are 14.5%, 7.6%, and 8.0%, respectively The CVs show that the La and F dual-doped spinel displays a better reversibility than LiMn2O4.
基金Support by the Key Scientific and Technological Project of Hainan Province (No. 080137)the Key Project of University (No. hd09×m10)
文摘Low larval survival,poor settlement,and abnormal metamorphosis are major problems in seed production of donkey-ear abalone Haliotis asinina.We examined the effects of chemical cues including epinephrine,nor-epinephrine,and serotonin on larval survival,settlement,and metamorphosis in order to determine the possibility of using these chemicals to induce the problems.The results show that epinephrine could enhance metamorphosis rate at 10-6 mol/L only but higher concentrations(10-3-10-4 mol/L);and nor-epinephrine could inhibit the performance significantly,and serotonin could increase significantly the performance at a wide-range concentration(10-3-10-6 mol/L).Treatment with serotonin at 10-5 mol/L for 72 hours resulted in the highest settlement rate(42.2%) and survival rate(49.3%),while at 10-4 mol/L for 72 hours resulted in the highest metamorphosis rate(38.8%).Therefore,serotonin may be used as a fast metamorphosis inducer in abalone culture.
基金This work was financially supported by the Middle Age and Youth Backbone Teacher Project (2004) of Henan Province, China.
文摘To improve the cycle performance of eco-friendly and cost-effective spinel LiMn2O4 as the Li secondary batteries, the Th-doped LiThxMn1-xO4 spinel powers were synthesized by solid-state method. The starting materials, Li2CO3, MnO2 and Th(NO3)4·4H2O, were mixed uniformly using a traditional ball milling, which resulted in a uniform particle size distribution in the mixed powers. Tests of X-ray diffraction, SEM, impedance spectra and charge-discharge were carried out for LiThxMn1-xO4 cathode materials. Results show that the synthesized LiTh0.01Mn1.99O4 material exhibits standard spinel structure, regular particle morphology and excellent property of charge-discharge for big current. The capacity retention of the material modified by doping Th is more than 85.1% of the first discharge specific capacity of 111.5 mAh·g-1 after 20 cycles at the current rate 1C, while the pristine LiMn2O4 is only 57% of the first discharge specific capacity of 110.2 mAh·g-1 after the same cycles at the same current rate.
基金This work was financially supported by the Middle Age and Youth Backbone Teacher Project (2004) of Henan Province, China.
文摘In the search for improved materials for rechargeable lithium batteries, LiFePO4 offers interesting possibilities because of its low raw materials cost, environmental friendliness and safety. The main drawback with using the material is its poor electronic conductivity and this limitation has to be overcome. Here Al-doped LiFePO4/C composite cathode materials were prepared by a polymer-network synthesis technique. Testing of X-ray diffraction, charge-discharge, and cyclic voltammetry were carried out for its performance. Results show that Al-doped LiFePO4/C composite cathode materials have a high initial capacity, good cycle stability and excellent low temperature performance. The electrical conductivity of LiFePO4 material can be obviously improved by doping Al. The better electrochemical performances of Al-doped LiFePO4/C composite cathode materials have a connection with its conductivity.
基金supported by the National Natural Science Foundation of China(Nos.51972342,5187205652062046,and 51702275)the Taishan Scholar Project of Shandong Province(ts20190922)+3 种基金the Key Basic Research Projects of Natural Science Foundation of Shandong province(ZR2019ZD51)the CAS Key aboratory of Carbon Materials(KLCMKFJJ2012)the Science Foundation of Xinjiang Autonomous Region(2020D01C019)the Fundamental Research Funds for the Central Universities(20CX05010A)。
文摘1.Introduction Carbon materials have been widely investigated as the anode materials for Na+storage due to their moderate capacity,good stability,and low cost.The Na+storage mechanisms of carbon are generally classified into diffusion-controlled interlayer insertion/desertion and capacitive-controlled surface adsorption/desorption[1].
基金supported by the National Natural Science Foundation of China (Nos.51871069 and 52071093)the Fundamental Research Funds for the Central Universities (No.3072020CF1009)+2 种基金the Science and Technology Innovation Major Project of Ningbo City, China (No.2019B10103)the Domain Foundation of Equipment Advance Research of 13th Five-year Plan (No.61409220118)the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization (No.RERU2020008)。
文摘Magnesium(Mg) alloys, as the lightest metal engineering materials, have broad application prospects.However, the strength and ductility of traditional Mg alloys are still relativity low and difficult to improve simultaneously.Refining grain size via the deformation process based on the grain boundary strengthening and the transition of deformation mechanisms is one of the feasible strategies to prepare Mg alloys with high strength and high ductility.In this review, the effects of grain size on the strength and ductility of Mg alloys are summarized, and fine-grained Mg alloys with high strength and high ductility developed by various severe plastic deformation technologies and improved traditional deformation technologies are introduced.Although some achievements have been made, the effects of grain size on various Mg alloys are rarely discussed systematically and some key mechanisms are unclear or lack direct microscopic evidence.This review can be used as a reference for further development of high-performance fine-grained Mg alloys.
基金supported by the National Natural Science Foundation of China(No.52071093,51871069,51701200)Fundamental Research Funds for the Central Universities(3072020CF1009)+1 种基金the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(RERU2020012)Grant-in-Aid for JSPS Fellows from the Japan Society for the Promotion of Science。
文摘Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallization(DRX)fraction and coarsened DRX grains,which further suggests weakened basal fiber texture for the studied alloy.This is mainly due to the rising temperature from massive deformation heat when hot-extrusion.As a result,greater ER corresponds to a decreased strength but improved ductility.Finally,transmission electron microscopy(TEM)observations reveal that the dominant intermetallic phase,Mg_(3)Sm,is metastable,and it will transform into Mg_(41)Sm_(5)during extrusion with high-ER.This transformation leads to the accumulation of surplus Sm and Zn atoms,which induces the precipitation of Sm Zn_(3)phase at the surface of Mg_(41)Sm_(5)matrix.
基金National Natural Science Foundation of China(No.20336010)National Basic Research Programme of China(No.2003CB716008)
文摘Ionic liquids(ILs) are attracting much attention in various fields of chemical synthesis, electrochemical applications, liquid-liquid extractions, as well as biotransformations. Among those fields, the application of ILs as the potential green solvent for a wide variety of synthetic processes is an area of intense researches. High yield, high selectivity, and good catalytic charac-teristics have usually been achieved. After the isolation of products, ILs can usually be recovered and recycled many times by simple treating procedures, such as, filtration, extraction, and dryness.
基金Supported by National Program on Key Basic Research Projects (2004CB418500).
文摘A new polymer, poly-silicon-ferric with oxidization (PSFN) coagulant was produced by adding KMnO4 and stabilizer M to poly-silicon-ferric (PSF) coagulant. The micro properties of PSFN was investigated with optical microscope, transmission electron microscope(TEM), ultraviolet/visible absorption(UVA) scanning, infrared(IR) spectrometer and oxidation-reduction potential (ORP) meter respectively, compared to that of PSF. The coagulation behavior by PSFN was investigated compared to that by PSF. The results show that the micro properties of PSF have been changed greatly due to the addition of KMnO4, and there exists KMnO4 unattached in PSFN. A kind of tetrahedron structure somewhat like the connection of Si-O-Si bonds may be formed by the complexation of Mn (maybe in various valence) with PSF. PSFN has lower turbidity removal than PSF at lower dose and achieves the same when the dose reaches a definite amount, while the removal of UV254 by PSFN is higher than that by PSF almost over entire dose range with the largest difference of about 17%. PSFN has more oxidization function at acidic condition than that at basic condition, and gives stronger ability of application for treating various waters than that by PSF.
基金supported by the National Natural Science Foundation of China(Nos.51672055,51972342,51872656,and 51702275)the Taishan Scholar Project of Shandong Province(ts20190922)+3 种基金the Key Basic Research Project of Natural Science Foundation of Shandong Province(ZR2019ZD51)the Xinjiang Tianshan Xuesong Project(2018XS28)the Scientific Research Program of the Higher Education Institution of Xinjiang(XJEDU2017S003)the Xinjiang Tianchi Doctoral Project。
文摘The development of lithium-sulfur batteries(LSBs)is restricted by their poor cycle stability and rate performance due to the low conductivity of sulfur and severe shuttle effect.Herein,an N,O co-doped graphene layered block(NOGB)with many dents on the graphene sheets is designed as effective sulfur host for high-performance LSB s.The sulfur platelets are physically confined into the dents and closely contacted with the graphene scaffold,ensuring structural stability and high conductivity.The highly doped N and O atoms can prevent the shuttle effect of sulfur species by strong chemical adsorption.Moreover,the micropores on the graphene sheets enable fast Li^+transport through the blocks.As a result,the obtained NOGB/S composite with 76 wt%sulfur content shows a high capacity of 1413 mAh g^-1 at 0.1 C,good rate performance of 433 mAh g^-1 at 10 C,and remarkable stability with 526 mAh g^-1 at after 1000 cycles at 1 C(average decay rate:0.038%per cycle).Our design provides a comprehensive route for simultaneously improving the conductivity,ion transport kinetics,and preventing the shuttle effect in LSBs.
基金the National Doctorial Research Foundation of China (No.20030213007).
文摘The acrylonitrile-butadiene-styrene (ABS) surface was etched by dipping it into chromic acid-sulfuric acid containing a trace amount of palladium. The surface roughness, activity, and valence bond were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The results showed that with the increase of Pd concentration in the etching solution the ABS surface roughness reduced. The ratio of O to C increases and forms a large amount of O=C?O functional groups by dipping into Pd contained etching solution, thus the amount of colloids palladium adsorption increases. The carboxyl group acts as the ad- sorption site for the Pd/Sn catalyst.
文摘Thin films of incompatible polymer blends can form a variety of structures during preparation and subsequent annealing process. For the polymer blend system consisting of polystyrene and poly(styrene-co-p-bromo-styrene), i.e., PS/PBrxS, its compatibility could be adjusted by varying the degree of bromination and the molecular weight of both components comprised. In this paper, surface chemical compositions of the cast and the annealing films were investigated by X-ray photoelectron spectroscopy (XPS) and contact angle measurement; meanwhile, surface topographical changes are followed by atomic force microscopy (AFM). In addition, substantial attention was paid to the effect of annealing on the morphologic variations induced by phase separation and/or dewetting of the thin film. Moreover, the influences of the molecular weight, Mw, as well as the brominated degree, x%, on the sample surface are explored systematically, and the corresponding observations are explained in virtue of the Flory-Huggins theory, along with the dewetting of the polymer thin film.
基金supported by the Science and Technology Bureau of Jinhua City (No. 2003-01-179)
文摘A new 4-chlorobenzoic acid bridge Co(Ⅱ ) complex [[Co2(2,2'-bpy)2(μ-L)e(L)2(μ-H2O)] (HL = 4-chlorobenzoic acid) has been obtained by hydrothermal synthesis, and X-ray single-crystal diffraction analysis shows that it crystallizes in the monoclinic system, space group C2/c with a = 22.537(5), b = 16.212(3), c = 15.306(3) A, β= 124.37(3)°, V= 4616.1(16)A3, Mr = 1070.45, Dc = 1.540 g/cm3, Z = 4, p = 1.012 mm-1, F(000) = 2176, the final R = 0.0338 and wR= 0.0810. The title complex is composed of dinuclear [Co2(2,2'-bpy)2(μ-L)2(L)2(μ-HaO)] molecules. Each Co(Ⅱ ) atom is coordinated by two nitrogen atoms from one 2,2’-bipyridine ligand, three oxygen atoms from three 4-chlorobenzoic ions and another oxygen atom from one water molecule. The two Co(Ⅱ) atoms are connected by two 4-chlorobenzoic ions and one bridged water molecule. The dinuclear molecules are interlinked by hydrogen bond and π-π stacking interactions into a three-dimensional supramolecular network.
基金supported by the National Natural Science Foundation of China (U1162114)the PetroChina Innovation Foundation (2012D-5006-0501)+2 种基金the Tianjin Municipal Education Commission of China (20110505)the Natural Science Foundation of Tianjin (12JCQNJC06000)the Program for New Century Excellent Talents in University (NCET-07-0142)
文摘Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction pressure and Al/Cr molar ratio on ethylene tetramerization were investigated in detail. Chromium was uniformly and firmly immobilized on the support and could not be leached off by methylaluminoxane. The supported catalyst, upon being activated with methylaluminoxane, exhibited catalytic activity of 1.70×107 g/(mol Cr·h) for ethylene tetramerization to form 1-octene at a reaction temperatures of 80 ℃, a pressure of 2.0 MPa and an Al/Cr molar ratio of 300. The supported catalyst presented a good tolerance to high temperature.
基金JSPS KAKENHI for Scientific Research on Innovative Areas“Materials Science of a Mille-feuille Structure(Grant Numbers JP18H05475,JP18H05479)”the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(RERU2020012)+1 种基金“Nanotechnology Platform”of the MEXT,JapanGrant-in-Aid for JSPS Fellows(JP19F19775)。
文摘The effect of Gd content on the microstructure and tensile properties of as-cast Mg-Sm-Zn-Zr alloy has been systematically investigated.In the Mg-3Sm-0.5Zn-0.5Zr alloy, the intermetallic compounds with multiple morphologies are identified as Mg_(3)Sm phase. In addition to Mg_(3)RE phase, Mg_(5)RE phase originated from Gd addition is observed in Gd-modified alloys. It should be noted that the lattice parameters of all the observed intermetallic compounds are significantly reduced by Zn segregation. The segregation behavior of Zn in Mg_(3)Sm phase is inhibited to some extent by Gd addition due to the electronegativity difference between Sm/Gd and Zn elements. In addition, the increased Gd content effectively leads to much more accumulation of solute atoms in front of the liquid-solid interface during solidification, which can prominently promote nucleation in liquid region and then refine grains. The tensile yield stress of the present alloys is thus improved with increasing Gd addition. Finally, Gd-modified alloys exhibit significantly age-hardening effect, which can be mainly attributed to the high-volume fraction and high density nano-scale precipitates.
基金supported by Fundamental Research Funds for the Central Universities(No.DL12BA06)Harbin Science and Technology Innovation Talent Research Special Funds(2015RAQXJ002)
文摘Phototoxic treatments of pathogenic bacteria and fungi of trees induce oxidative damage that is preferable to toxic chemical treatment.Here,we used green methods to synthesize Chlorin e6 from chlorophyll a,which was extracted from crude silkworm excrement using concentrated(strong)alkali hydrolysis and acidification.The photosensitive bactericidal activities of the new chlorin were tested in vitro,and possible mechanisms of action are discussed.The results showed that Chlorin e6 can be lightactivated to have bactericidal activity against Escherichia coli,Bacillus subtilis and Fusarium oxysporum,but it had little bactericidal effect in the dark.This kind of chlorin compounds has great potential as a natural phototoxic antimicrobial compound to control harmful bacteria on the leaves in forestry systems.
基金financially supported by the National Natural Science Foundation of China(nos.21773060,51774002,and 21601054)Fundamental Research Funds for the Central Universities(no.N182304014)+1 种基金Youth Innovation Team Project of Science and technology of Heilongjiang University(2018-KYYWF-1593)Young Scholar Project of the Long Jiang Scholars Program(Q201818)
文摘SrLi_(2)Ti_(6)O_(14)(SLTO)coated with different amount of ZrO_(2)was successfully prepared.The as-obtained composites are stacked by a series of particles with a pure phase structure and a good crystallinity.Furthermore,ZrO_(2)coating not only enhances the structural stability of the materials but also facilitates the diffusion of lithium through the SEI film.As a result,the redox polarization was reduced,and the reversibility of the electrochemical reaction was enhanced.Particularly,SLTO-ZrO_(2)-2 sample delivers a high initial lithiation capacity of 283.6 mA h g^(-1),and the values maintain at 251.7,228.0,207.4,175.3,and 147.7 mA h g^(-1)at the current densities of 0.13,0.26,0.54,1.31,and 2.62 A g^(-1),respectively.Our experiment also confirmed that SLTO materials coated with ZrO_(2)are suitable for high power density applications,and the lithiation specific energy efficiency of SLTO-ZrO_(2)-2 is 200%as high as that of pure SLTO at a power density of 1257 W kg^(-1).
文摘Nickel-base superalloys are materials of choice for manufacturing hot-section components in gas turbines due to their superior mechanical properties at high temperatures [1]. For maintaining and improving the properties, this kind of materials are often cast into single crystal form. Nevertheless, severe service conditions of high temperature and high pressure, often cause tip and platform damages.
文摘Electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) techniques were used to detect stress corrosion cracking(SCC) on 40Cr steel specimens exposed to the acidified chloride solution at ambient. To test these two techniques,slow strain rate tensile(SSRT) tests were performed with 40Cr specimen in the identical corrosive solution at room temperature. In impedance measurements,phase shifts in frequency range from 1 to 1 000 Hz show a clear difference between the stressed and non-stressed specimens,suggesting that stress corrosion cracks are detected by the impedance measurements. EN signals in the process of SCC were recorded and then analyzed by standard deviation(STD). On the other hand,the mechanical properties,such as maximum tensile strength(MTS) and fracture strain(FS) measured by the SSRT,decrease significantly when the specimens are exposed to the corrosive solution relative to that in an inert medium. The SSRT results are consistent with fractography of the tested specimens by scanning electron microscopy(SEM). Analysis of the fracture surface clearly shows intergranular attack,suggesting that stress corrosion cracks are formed.