Kitaev quantum spin liquids have attracted significant attention in condensed matter physics over the past decade.To understand their emergent quantum phenomena,high-quality single crystals of substantial size are ess...Kitaev quantum spin liquids have attracted significant attention in condensed matter physics over the past decade.To understand their emergent quantum phenomena,high-quality single crystals of substantial size are essential.Here,we report the synthesis of single crystals of the Kitaev quantum spin liquid candidate RuBr_(3),achieving millimeter-sized crystals through a self-flux method under high pressure and high temperature conditions.The crystals exhibit well-defined cleavage planes with a lustrous appearance.Transport characterizations exhibit a narrow band-gap semiconducting behavior with 0.13 eV and 0.11 eV band-gap in ab plane and along𝑐axis,respectively.Magnetic measurement shows a transition to antiferromagnetic(AFM)state at approximately 29K both in ab plane and along the c axis.Notably,the N′eel temperature increases to 34K with an applied magnetic field of up to 7T in the ab plane,but without any change along𝑐axis.The large size and high quality of RuBr3 single crystals provide a valuable platform for investigating various interactions,particularly the Kitaev interaction,and for elucidating the intrinsic physical properties of Kitaev quantum spin liquids.展开更多
Gas rapid unloading(GRU)is an innovative technology for ore comminution.Increasing the production of fine powder in each ore grinding cycle is vital for scaling up the GRU method to industrial applications.This study ...Gas rapid unloading(GRU)is an innovative technology for ore comminution.Increasing the production of fine powder in each ore grinding cycle is vital for scaling up the GRU method to industrial applications.This study utilizes laboratory experiments to demon-strate that moderately reducing the orifice size significantly enhances pulverization and increases fine particle yield.Numerical simulations suggest that smaller orifices improve pulverization by increasing jet speed,reducing pressure drop,and creating a larger pressure difference inside and outside the unloading orifice.The orifice size should be optimized based on feed size to ensure efficient ore discharge.Reducing the unloading orifice size improves GRU grinding efficiency and energy use,offering guidance for the design of ore discharge ports in future industrial-scale equipment.展开更多
A centrifugal fan with the high speed and compact dimensions is studied numerically and experimentally. The centrifugal fan consists of a shrouded impeller rotating at 34 000 r/min with a small tip clearance 0.7 mm to...A centrifugal fan with the high speed and compact dimensions is studied numerically and experimentally. The centrifugal fan consists of a shrouded impeller rotating at 34 000 r/min with a small tip clearance 0.7 mm to the fixed outer casing. Computational models with/without the tip clearance are built and the κ-ω shear stress transport （SST） turbulence model and the unstructured mesh are applied to the numerical simulation for unsteady solutions. The overall performance is measured on a standard experimental bench and the major flow feature of each component inside the centrifugal fan is numerically investigated. In the presence of the tip clearance due to the difference of static pressure between leading and trailing edges of the clearance, i. e. , leading and trailing edges of the impeller, a strong return flow exists inside the clearance passage and re-circulates the main stream inside the impeller passage, and produces the strong flow interaction, thus changing the flow field and influencing the overall performance.展开更多
In this study, phosphorus modification by trimethyl phosphate impregnation was employed to enhance the hydrothermal stability of nano‐sized HZSM‐5 zeolites. A parallel modification was studied by ammonium dihydrogen...In this study, phosphorus modification by trimethyl phosphate impregnation was employed to enhance the hydrothermal stability of nano‐sized HZSM‐5 zeolites. A parallel modification was studied by ammonium dihydrogen phosphate impregnation. The modified zeolites were subjected to steam treatment at 800 °C for 4 h (100% steam) and employed as catalysts for olefin catalyticcracking (OCC) of full‐range fluid catalytic cracking (FCC) gasoline. X‐ray diffraction, N2 physicaladsorption and NH3 temperature‐programmed desorption analysis indicated that, although significantimprovements to the hydrothermal stability of nano‐sized HZSM‐5 zeolites can be observedwhen adopting both phosphorus modification strategies, impregnation with trimethyl phosphatedisplays further enhancement of the hydrothermal stability. This is because higher structural crystallinityis retained, larger specific surface areas/micropore volumes form, and there are greaternumbers of surface acid sites. Reaction experiments conducted using a fixed‐bed micro‐reactor(catalyst/oil ratio = 4, time on stream = 4 s) showed OCC of full‐range FCC gasoline-under a fluidized‐bed reaction mode configuration-to be a viable solution for the olefin problem of FCC gasoline.This reaction significantly decreased the olefin content in the full‐range FCC gasoline feed, andspecifically heavy‐end olefins, by converting the olefins into value‐added C2–C4 olefins and aromatics.At the same time, sulfide content of the gasoline decreased via a non‐hydrodesulfurization process.Nano‐sized HZSM‐5 zeolites modified with trimethyl phosphate exhibited enhanced catalytic performance for OCC of full‐range FCC gasoline.展开更多
Cu(NO3)(2) and (NH4)(6)H(2)W(12)O(40)center dot 4H(2)O were used to prepare W/Cu nanosized composite powder by sol-gel technique. The influences of heat treatment process, pH value of the solution and the amount of an...Cu(NO3)(2) and (NH4)(6)H(2)W(12)O(40)center dot 4H(2)O were used to prepare W/Cu nanosized composite powder by sol-gel technique. The influences of heat treatment process, pH value of the solution and the amount of an addition agent on particle size were investigated by DSC, XRD and TEM. The results show that, at a certain heat treatment temperature, the W/Cu nanoparticle size increases with the pH value or the amount of the addition agent increasing.展开更多
Chemical solution deposited CdSe particulate film possess nanocrystalline structure and exhibit quantum size effects. By changing the temperature of chemical deposition and subsequent annealing, CdSe particulate films...Chemical solution deposited CdSe particulate film possess nanocrystalline structure and exhibit quantum size effects. By changing the temperature of chemical deposition and subsequent annealing, CdSe particulate films with different particle sizes can be obtained.展开更多
The mechanical properties of the hot-rolled plates of Ti steel and Ti-Mo steel after isothermal transformation in a temperature range of 600 700 ℃ for 60 min have been tested, and the microstructures of the matrix an...The mechanical properties of the hot-rolled plates of Ti steel and Ti-Mo steel after isothermal transformation in a temperature range of 600 700 ℃ for 60 min have been tested, and the microstructures of the matrix and the characteristics of precipitated nanometer-sized carbides have also been examined by scanning electron microscopy and transmission electron microscopy. The precipitation regularity of nanometer-sized carbides has been studied by thermodynamic method and the contributions of corresponding strengthening mechanisms to the total yield strength have been calculated. The tensile strength of hot-rolled Ti-Mo ferritie steel can achieve 780 MPa with an elongation of 20.0% after being isothermally treated at 600 ℃ for 60 rain, and the tensile strength of Ti steel is 605 MPa with an elongation of 22.7%, according to the results of tensile tests. The critical nucleation size of （Ti,Mo）C is smaller than that of TiC at a given isothermal temperature, but the nucleation rate of （Ti, Mo）C is larger than that of TiC. The grainrefinement strengthening and precipitation strengthening contribute the main amount of the total yield strength. The major increase in yield strength with the decrease of isothermal temperature results from the contribution of precipi tation strengthening. The contribution of precipitation strengthening to the yield strength of the steels has been esti mated. The ferrite phase can be strengthened by about 400 MPa through precipitation strengthening in Ti-Mo steel isothermally treated at 600 ℃ for 60 rain, which is about 200 MPa higher than that of Ti steel under the same conditions.展开更多
An operando dual‐beam Fourier transform infrared (DB‐FTIR) spectrometer was successfully developed using a facile method. The DB‐FTIR spectrometer is suitable for the real‐time study of the dynamic surface process...An operando dual‐beam Fourier transform infrared (DB‐FTIR) spectrometer was successfully developed using a facile method. The DB‐FTIR spectrometer is suitable for the real‐time study of the dynamic surface processes involved in gas/solid heterogeneous catalysis under real reaction conditionsbecause it can simultaneously collect reference and sample spectra. The influence of gas‐phasemolecular vibration and heat irradiation at real reaction temperatures can therefore be eliminated.The DB‐FTIR spectrometer was successfully used to follow the transformation of isobutene over nano‐sized HZSM‐5 zeolite under real reaction conditions.展开更多
Rhenium(Re)has recently emerged as a promising catalyst in hydrogen evolution reactions(HER)due to its metalhydrogen interaction,which resembles that of Pt.The availability of small-sized Re nanoparticles with abundan...Rhenium(Re)has recently emerged as a promising catalyst in hydrogen evolution reactions(HER)due to its metalhydrogen interaction,which resembles that of Pt.The availability of small-sized Re nanoparticles with abundant accessible active sites is nevertheless limited by the required high-temperature preparation conditions.展开更多
The purpose of the current study is to explore the frictional behavior of a micro- sized superconducting fiber at the low-temperature condition. At first, a highly precise tribometer composed of a superconducting fibe...The purpose of the current study is to explore the frictional behavior of a micro- sized superconducting fiber at the low-temperature condition. At first, a highly precise tribometer composed of a superconducting fiber wrapping around a cylinder made of pure Cu was immersed in liquid nitrogen. The force and displacement resolutions of the experimental system were as high as 0.01 mN and 0.03 ~m, respectively. The NbTi fibers with diameters ranging from 22.9 to 115 ~m were used in the experiments, and their frictional behaviors in three media, i.e., liquid nitrogen, air and water, were systemically investigated. It was found that the frictional force in air showed a remarkable size effect. The existence of water medium could significantly reduce the frictional force, but could not eliminate the size effect. For the samples with the same diameter, the frictional force in liquid nitrogen was about 1.4 times of that in air, accompanied with remark- able stick-slip phenomenon. Notably, the fiber＇s frictional behavior in liquid nitrogen showed no dependence on diameter. In order to interpret these phenomena, the frictional behaviors of the fibers in air, water and liquid nitrogen were simulated using a modified spring-slider model, by taking into account the influence of hydrophilicity on surface roughness, and the influence of surface roughness on the fiber＇s frictional behavior. The simulation results were consistent with the experimental data qualitatively.展开更多
The pursuit of high-energy cathode materials has been focused on raising the charging cutoff voltage of nickel (Ni)-rich layered oxide cathode such as LiNi_(0.8)Co_(0.1)Mn_(0.1)O2 (NCM811). However, the NCM811 suffers...The pursuit of high-energy cathode materials has been focused on raising the charging cutoff voltage of nickel (Ni)-rich layered oxide cathode such as LiNi_(0.8)Co_(0.1)Mn_(0.1)O2 (NCM811). However, the NCM811 suffers from rapid capacity fading upon cycling at cutoff voltage higher than 4.5 V, owing to their structural degradation and labile surface reactivity. Surface-coating with solid electrolytes has been recognized as an effective method to mitigate the performance failure of NCM811 at high voltage. Herein, the nano-sized Li_(6.4)La_(3)Ta_(0.6)Zr_(1.4)O_(12) (LLZTO) is uniformly coated on the surface of single-crystal NCM811 particles, accompanied with the long-range Ta^(5+) diffusion into the transition metal layer of NCM811 lattice. It is revealed that the LLZTO coating can not only inhibit the surface reactions of NCM811 with liquid electrolytes but also play an important role in suppressing the bulk microcracking within the NCM811 particles. The incorporation of Ta^(5+) ion expands the lattice spacing and thereby improves the homogeneity of the Li^(+) diffusion in the single-crystal NCM811, which alleviates the mechanical strain and intragranular cracks caused by nonuniform phases-transformation at high charging voltage. The synergy of surface protection and structural stabilization realized by LLZTO coating enables the NCM811-based lithium batteries to achieve a remarkable electrochemical performance. Typically, LLZTO coated NCM811 delivers a high reversible specific capacity of 202.1 mAh⋅g^(−1) with an excellent capacity retention as high as 70% over 1000 cycles upon charging to 4.5 V at 1 C.展开更多
An anomalous dielectric behavior in nanometer-sized amocthous silicon nitride is reported. The dielectric constant of nanometer-sized ajnorph. silicon nitride has strong dependence on frequency at room temperature (RT...An anomalous dielectric behavior in nanometer-sized amocthous silicon nitride is reported. The dielectric constant of nanometer-sized ajnorph. silicon nitride has strong dependence on frequency at room temperature (RT),which is completely different from the conventional coarse-grain silicon nitride. The maximum of the dielectric constant of nanometer-sized amorphous silicon nitride at KT is about 40 times larger than that of the conventional silicon nitride. The anomalous dielectric behavior is explained by a kind of mech&nism of pola.rizationt that is, interfacial polarization.展开更多
Small and medium-sized companies in most EU countries form a considerable share in the total number of companies and are also an important development impeller of the entire economy. Therefore, one of the most essenti...Small and medium-sized companies in most EU countries form a considerable share in the total number of companies and are also an important development impeller of the entire economy. Therefore, one of the most essential goals of accounting authorities in the EU is accomplishing the harmonization of accounting regulations for these companies. In this paper, the author have discussed and explained the main motifs and impediments for this harmonization. One of the main motifs is a big span and complexity of international standards of financial reports which is allowed and even prescribed in many countries. Some of the main impediments are a lack of uniformity as far as criteria for classification of small and medium-sized companies according to size are concerned as well as the determining of limitations up to which the requirements in accounting standards for small and medium-sized companies should be set.展开更多
This paper presents the amination reactions of electron deficient aryl chlorides promoted by Mg（OH）_2 without transition metals. Only using stoichiometric amount of nano sized Mg（OH）_2,good to moderate isolated yi...This paper presents the amination reactions of electron deficient aryl chlorides promoted by Mg（OH）_2 without transition metals. Only using stoichiometric amount of nano sized Mg（OH）_2,good to moderate isolated yields could be achieved in N-methylpyr-rolidone （NMP） after 24 h at 150℃.展开更多
Developmental and epileptic encephalopathies(DEEs)are neurological disorders generally involving medically intractable seizures and a diverse array of comorbid neuropsychiatric delays and deficits that may severely af...Developmental and epileptic encephalopathies(DEEs)are neurological disorders generally involving medically intractable seizures and a diverse array of comorbid neuropsychiatric delays and deficits that may severely affect cognition,mood,sleep,social behavior,movement control,learning,and/or memory.Dravet syndrome(DS),also known as Severe Myoclonic Epilepsy of Infancy.展开更多
We report high-resolution scanning tunneling microscopy(STM)study of nano-sized Pb islands grown on SrTiO3,where three distinct types of gaps with different energy scales are revealed.At low temperature,we find that t...We report high-resolution scanning tunneling microscopy(STM)study of nano-sized Pb islands grown on SrTiO3,where three distinct types of gaps with different energy scales are revealed.At low temperature,we find that the superconducting gap(△s)in nano-sized Pb islands is significantly enhanced from the one in bulk Pb,while there is no essential change in superconducting transition temperature Tc,giving rise to a larger BCS ratio 2△s/kBTc^8.31 and implying stronger electron-phonon coupling.The stronger coupling can originate from the interface electron-phonon interactions between Pb islands and SrTiO3.As the superconducting gap is totally suppressed under applied magnetic field,the Coulomb gap with apparent V-shape emerges.Moreover,the size of Coulomb gap(Ac)depends on the lateral size of Pb islands(R)with △c-1/R^035,indicating that quantum size effect can significantly influence electronic correlations.Our experimental results shall shed important light on the interplay among superconductivity,quantum size effect and correlations in nano-sized strong-coupling superconductors.展开更多
Nanometer sized SnO 2 particles were prepared by a sol gel method using inorganic salt as a precursor material. Its crystallization was investigated by means of TG DTA,IR absorption spectra, X ray diffractometry ...Nanometer sized SnO 2 particles were prepared by a sol gel method using inorganic salt as a precursor material. Its crystallization was investigated by means of TG DTA,IR absorption spectra, X ray diffractometry and TEM as well as its resistivity change and the gas sensitivity varied with temperature were measured in various reducing gas. The results indicate that well crystallized nano sized SnO 2 with size around 15nm can be obtained at annealing temperature 600℃. The activation energy for the growth of nano SnO 2 was calculated to be 26.55kJ.mol 1 when the annealing temperature was higher than 500℃. The measurements also show that there is a peculiar resistance change varied with temperature for nano SnO 2.It has relevance to the increase in surface adsorbed oxygen. The selective detectivities to C 4H 10 and petrol can be increased when ruthenium ion was doped in nano SnO 2 as a catalyst and so do the gas sensitivity to CO,CH 4,H 2 etc. when rhodium ion was doped in.The detection to the several reducing gas can be realized when the temperature ranged from 260℃ to 400℃.展开更多
On the basis of analyzing the reliability of the organization’ management chain of the large and medium- sized project in the construction period, the paper studies the factors influencing the reliability of the orga...On the basis of analyzing the reliability of the organization’ management chain of the large and medium- sized project in the construction period, the paper studies the factors influencing the reliability of the organi-zation management chain, which, corresponding to four elements of management chain – “Management Loop”, “Management Link”, “Management Chain”, and “Management Network”, can be summarized as project main body, interface management, connection sequence and management model. The paper then re-searches on the specific influencing factors from the above-mentioned four aspects.展开更多
The inhibitory effect of phosphate on the crystal grain growth of nanosized titania during high temperature calcination was investigated. Nanosized titanium dioxide powders prepared by hydrolysis of titanium tetrachlo...The inhibitory effect of phosphate on the crystal grain growth of nanosized titania during high temperature calcination was investigated. Nanosized titanium dioxide powders prepared by hydrolysis of titanium tetrachloride were soaked in phosphate solutions with different concentrations. The obtained powders calcined at various temperatures were characterized by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, and X-ray photoelectronic spectroscopy （XPS）. The grain size of the samples without phosphate treatment increased quickly when calcined at high temperatures, while the grain size of the samples with phosphate modification increased slowly when calcined at the same temperature. This phenomenon implies that phosphate treatment plays an important role in inhibiting the crystal grain growth of titania. The possible mechanism of the inhibition effect of phosphate on titania is discussed.展开更多
In the context of government appeal of " mass entrepreneurship and innovation",all areas launched the movement of " mass entrepreneurship" and " grassroots entrepreneurship". As parts of ...In the context of government appeal of " mass entrepreneurship and innovation",all areas launched the movement of " mass entrepreneurship" and " grassroots entrepreneurship". As parts of vitality of China's market economy,small and medium sized private enterprises become grassroots of market competition in talents,funds,and technologies. This paper combined three levels of entrepreneurial spirit and small and medium sized private enterprises,studied acting mechanism of entrepreneurial spirit,discussed competitive power of small and medium sized private enterprises,and recommended that small and medium sized private enterprises should cultivate core competitive power,adapt to external environment,and create external environment support,to realize sound development.展开更多
基金supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406000 and 2022YFA1403800)the National Natural Science Foundation of China(Grant Nos.12474002,22171283,22203031,12434005,12204515,and 12074175)support of the Young Elite Scientists Sponsorship Program by CAST(Grant No.2022QNRC001)。
文摘Kitaev quantum spin liquids have attracted significant attention in condensed matter physics over the past decade.To understand their emergent quantum phenomena,high-quality single crystals of substantial size are essential.Here,we report the synthesis of single crystals of the Kitaev quantum spin liquid candidate RuBr_(3),achieving millimeter-sized crystals through a self-flux method under high pressure and high temperature conditions.The crystals exhibit well-defined cleavage planes with a lustrous appearance.Transport characterizations exhibit a narrow band-gap semiconducting behavior with 0.13 eV and 0.11 eV band-gap in ab plane and along𝑐axis,respectively.Magnetic measurement shows a transition to antiferromagnetic(AFM)state at approximately 29K both in ab plane and along the c axis.Notably,the N′eel temperature increases to 34K with an applied magnetic field of up to 7T in the ab plane,but without any change along𝑐axis.The large size and high quality of RuBr3 single crystals provide a valuable platform for investigating various interactions,particularly the Kitaev interaction,and for elucidating the intrinsic physical properties of Kitaev quantum spin liquids.
基金financially supported by the National Natural Science Foundation of China(No.51934001)。
文摘Gas rapid unloading(GRU)is an innovative technology for ore comminution.Increasing the production of fine powder in each ore grinding cycle is vital for scaling up the GRU method to industrial applications.This study utilizes laboratory experiments to demon-strate that moderately reducing the orifice size significantly enhances pulverization and increases fine particle yield.Numerical simulations suggest that smaller orifices improve pulverization by increasing jet speed,reducing pressure drop,and creating a larger pressure difference inside and outside the unloading orifice.The orifice size should be optimized based on feed size to ensure efficient ore discharge.Reducing the unloading orifice size improves GRU grinding efficiency and energy use,offering guidance for the design of ore discharge ports in future industrial-scale equipment.
文摘A centrifugal fan with the high speed and compact dimensions is studied numerically and experimentally. The centrifugal fan consists of a shrouded impeller rotating at 34 000 r/min with a small tip clearance 0.7 mm to the fixed outer casing. Computational models with/without the tip clearance are built and the κ-ω shear stress transport （SST） turbulence model and the unstructured mesh are applied to the numerical simulation for unsteady solutions. The overall performance is measured on a standard experimental bench and the major flow feature of each component inside the centrifugal fan is numerically investigated. In the presence of the tip clearance due to the difference of static pressure between leading and trailing edges of the clearance, i. e. , leading and trailing edges of the impeller, a strong return flow exists inside the clearance passage and re-circulates the main stream inside the impeller passage, and produces the strong flow interaction, thus changing the flow field and influencing the overall performance.
基金supported by the National Natural Science Foundation of China (21603023)the Petro China Innovation Foundation, China (2014D-5006-0501)~~
文摘In this study, phosphorus modification by trimethyl phosphate impregnation was employed to enhance the hydrothermal stability of nano‐sized HZSM‐5 zeolites. A parallel modification was studied by ammonium dihydrogen phosphate impregnation. The modified zeolites were subjected to steam treatment at 800 °C for 4 h (100% steam) and employed as catalysts for olefin catalyticcracking (OCC) of full‐range fluid catalytic cracking (FCC) gasoline. X‐ray diffraction, N2 physicaladsorption and NH3 temperature‐programmed desorption analysis indicated that, although significantimprovements to the hydrothermal stability of nano‐sized HZSM‐5 zeolites can be observedwhen adopting both phosphorus modification strategies, impregnation with trimethyl phosphatedisplays further enhancement of the hydrothermal stability. This is because higher structural crystallinityis retained, larger specific surface areas/micropore volumes form, and there are greaternumbers of surface acid sites. Reaction experiments conducted using a fixed‐bed micro‐reactor(catalyst/oil ratio = 4, time on stream = 4 s) showed OCC of full‐range FCC gasoline-under a fluidized‐bed reaction mode configuration-to be a viable solution for the olefin problem of FCC gasoline.This reaction significantly decreased the olefin content in the full‐range FCC gasoline feed, andspecifically heavy‐end olefins, by converting the olefins into value‐added C2–C4 olefins and aromatics.At the same time, sulfide content of the gasoline decreased via a non‐hydrodesulfurization process.Nano‐sized HZSM‐5 zeolites modified with trimethyl phosphate exhibited enhanced catalytic performance for OCC of full‐range FCC gasoline.
基金This Project was financially supported by the National Natural Science Foundation of China (No. 50471033).
文摘Cu(NO3)(2) and (NH4)(6)H(2)W(12)O(40)center dot 4H(2)O were used to prepare W/Cu nanosized composite powder by sol-gel technique. The influences of heat treatment process, pH value of the solution and the amount of an addition agent on particle size were investigated by DSC, XRD and TEM. The results show that, at a certain heat treatment temperature, the W/Cu nanoparticle size increases with the pH value or the amount of the addition agent increasing.
文摘Chemical solution deposited CdSe particulate film possess nanocrystalline structure and exhibit quantum size effects. By changing the temperature of chemical deposition and subsequent annealing, CdSe particulate films with different particle sizes can be obtained.
基金Sponsored by National Natural Science Foundation of China(51271035)
文摘The mechanical properties of the hot-rolled plates of Ti steel and Ti-Mo steel after isothermal transformation in a temperature range of 600 700 ℃ for 60 min have been tested, and the microstructures of the matrix and the characteristics of precipitated nanometer-sized carbides have also been examined by scanning electron microscopy and transmission electron microscopy. The precipitation regularity of nanometer-sized carbides has been studied by thermodynamic method and the contributions of corresponding strengthening mechanisms to the total yield strength have been calculated. The tensile strength of hot-rolled Ti-Mo ferritie steel can achieve 780 MPa with an elongation of 20.0% after being isothermally treated at 600 ℃ for 60 rain, and the tensile strength of Ti steel is 605 MPa with an elongation of 22.7%, according to the results of tensile tests. The critical nucleation size of （Ti,Mo）C is smaller than that of TiC at a given isothermal temperature, but the nucleation rate of （Ti, Mo）C is larger than that of TiC. The grainrefinement strengthening and precipitation strengthening contribute the main amount of the total yield strength. The major increase in yield strength with the decrease of isothermal temperature results from the contribution of precipi tation strengthening. The contribution of precipitation strengthening to the yield strength of the steels has been esti mated. The ferrite phase can be strengthened by about 400 MPa through precipitation strengthening in Ti-Mo steel isothermally treated at 600 ℃ for 60 rain, which is about 200 MPa higher than that of Ti steel under the same conditions.
基金supported by the National Natural Science Foundation of China (21603023)the PetroChina Innovation Foundation, China (2014D-5006-0501)~~
文摘An operando dual‐beam Fourier transform infrared (DB‐FTIR) spectrometer was successfully developed using a facile method. The DB‐FTIR spectrometer is suitable for the real‐time study of the dynamic surface processes involved in gas/solid heterogeneous catalysis under real reaction conditionsbecause it can simultaneously collect reference and sample spectra. The influence of gas‐phasemolecular vibration and heat irradiation at real reaction temperatures can therefore be eliminated.The DB‐FTIR spectrometer was successfully used to follow the transformation of isobutene over nano‐sized HZSM‐5 zeolite under real reaction conditions.
基金financially supported by the National Natural Science Foundation of China(Nos.22202222,52172221,52272229 and 21902113)the Natural Science Foundation of Jiangsu Province(Nos.BK20190225 and BK20200101)+4 种基金the National Key R&D Program of China(No.2021YFF0502000)Jiangsu Key Laboratory for Carbon-Based Functional Materials and DevicesSuzhou Key Laboratory of Functional Nano&Soft MaterialsCollaborative Innovation Center of Suzhou Nano Science&Technologythe Program of the Ministry of Education of China for Introducing Talents of Discipline to Universities。
文摘Rhenium(Re)has recently emerged as a promising catalyst in hydrogen evolution reactions(HER)due to its metalhydrogen interaction,which resembles that of Pt.The availability of small-sized Re nanoparticles with abundant accessible active sites is nevertheless limited by the required high-temperature preparation conditions.
基金This work is supported by the National Natural Science Foundation of China （No. 11622217）
文摘The purpose of the current study is to explore the frictional behavior of a micro- sized superconducting fiber at the low-temperature condition. At first, a highly precise tribometer composed of a superconducting fiber wrapping around a cylinder made of pure Cu was immersed in liquid nitrogen. The force and displacement resolutions of the experimental system were as high as 0.01 mN and 0.03 ~m, respectively. The NbTi fibers with diameters ranging from 22.9 to 115 ~m were used in the experiments, and their frictional behaviors in three media, i.e., liquid nitrogen, air and water, were systemically investigated. It was found that the frictional force in air showed a remarkable size effect. The existence of water medium could significantly reduce the frictional force, but could not eliminate the size effect. For the samples with the same diameter, the frictional force in liquid nitrogen was about 1.4 times of that in air, accompanied with remark- able stick-slip phenomenon. Notably, the fiber＇s frictional behavior in liquid nitrogen showed no dependence on diameter. In order to interpret these phenomena, the frictional behaviors of the fibers in air, water and liquid nitrogen were simulated using a modified spring-slider model, by taking into account the influence of hydrophilicity on surface roughness, and the influence of surface roughness on the fiber＇s frictional behavior. The simulation results were consistent with the experimental data qualitatively.
基金supported by the National Key R&D Program of China (Grant No.2023YFB2503900)the National Natural Science Foundation of China (Grant No.52372203)Youth Innovation Team of Universities in Shandong Province (Grant No.2023KJ359)。
文摘The pursuit of high-energy cathode materials has been focused on raising the charging cutoff voltage of nickel (Ni)-rich layered oxide cathode such as LiNi_(0.8)Co_(0.1)Mn_(0.1)O2 (NCM811). However, the NCM811 suffers from rapid capacity fading upon cycling at cutoff voltage higher than 4.5 V, owing to their structural degradation and labile surface reactivity. Surface-coating with solid electrolytes has been recognized as an effective method to mitigate the performance failure of NCM811 at high voltage. Herein, the nano-sized Li_(6.4)La_(3)Ta_(0.6)Zr_(1.4)O_(12) (LLZTO) is uniformly coated on the surface of single-crystal NCM811 particles, accompanied with the long-range Ta^(5+) diffusion into the transition metal layer of NCM811 lattice. It is revealed that the LLZTO coating can not only inhibit the surface reactions of NCM811 with liquid electrolytes but also play an important role in suppressing the bulk microcracking within the NCM811 particles. The incorporation of Ta^(5+) ion expands the lattice spacing and thereby improves the homogeneity of the Li^(+) diffusion in the single-crystal NCM811, which alleviates the mechanical strain and intragranular cracks caused by nonuniform phases-transformation at high charging voltage. The synergy of surface protection and structural stabilization realized by LLZTO coating enables the NCM811-based lithium batteries to achieve a remarkable electrochemical performance. Typically, LLZTO coated NCM811 delivers a high reversible specific capacity of 202.1 mAh⋅g^(−1) with an excellent capacity retention as high as 70% over 1000 cycles upon charging to 4.5 V at 1 C.
基金Supported by the National Natural Science Foundation of ChinaNational Advanced Material Committee of China.
文摘An anomalous dielectric behavior in nanometer-sized amocthous silicon nitride is reported. The dielectric constant of nanometer-sized ajnorph. silicon nitride has strong dependence on frequency at room temperature (RT),which is completely different from the conventional coarse-grain silicon nitride. The maximum of the dielectric constant of nanometer-sized amorphous silicon nitride at KT is about 40 times larger than that of the conventional silicon nitride. The anomalous dielectric behavior is explained by a kind of mech&nism of pola.rizationt that is, interfacial polarization.
文摘Small and medium-sized companies in most EU countries form a considerable share in the total number of companies and are also an important development impeller of the entire economy. Therefore, one of the most essential goals of accounting authorities in the EU is accomplishing the harmonization of accounting regulations for these companies. In this paper, the author have discussed and explained the main motifs and impediments for this harmonization. One of the main motifs is a big span and complexity of international standards of financial reports which is allowed and even prescribed in many countries. Some of the main impediments are a lack of uniformity as far as criteria for classification of small and medium-sized companies according to size are concerned as well as the determining of limitations up to which the requirements in accounting standards for small and medium-sized companies should be set.
文摘This paper presents the amination reactions of electron deficient aryl chlorides promoted by Mg（OH）_2 without transition metals. Only using stoichiometric amount of nano sized Mg（OH）_2,good to moderate isolated yields could be achieved in N-methylpyr-rolidone （NMP） after 24 h at 150℃.
基金supported by Dravet Syndrome Foundation,NIH/NINDS R01-NS112500.
文摘Developmental and epileptic encephalopathies(DEEs)are neurological disorders generally involving medically intractable seizures and a diverse array of comorbid neuropsychiatric delays and deficits that may severely affect cognition,mood,sleep,social behavior,movement control,learning,and/or memory.Dravet syndrome(DS),also known as Severe Myoclonic Epilepsy of Infancy.
基金the National Natural Science Foundation under Grant Nos.11674191 and 11825404the National Key Program for S&T Research and Development under Grant No No.2016YFA0301002the Beijing Advanced Innovation Center for Future Chip(ICFC).W.L.was also supported by Beijing Young Talents Plan.
文摘We report high-resolution scanning tunneling microscopy(STM)study of nano-sized Pb islands grown on SrTiO3,where three distinct types of gaps with different energy scales are revealed.At low temperature,we find that the superconducting gap(△s)in nano-sized Pb islands is significantly enhanced from the one in bulk Pb,while there is no essential change in superconducting transition temperature Tc,giving rise to a larger BCS ratio 2△s/kBTc^8.31 and implying stronger electron-phonon coupling.The stronger coupling can originate from the interface electron-phonon interactions between Pb islands and SrTiO3.As the superconducting gap is totally suppressed under applied magnetic field,the Coulomb gap with apparent V-shape emerges.Moreover,the size of Coulomb gap(Ac)depends on the lateral size of Pb islands(R)with △c-1/R^035,indicating that quantum size effect can significantly influence electronic correlations.Our experimental results shall shed important light on the interplay among superconductivity,quantum size effect and correlations in nano-sized strong-coupling superconductors.
文摘Nanometer sized SnO 2 particles were prepared by a sol gel method using inorganic salt as a precursor material. Its crystallization was investigated by means of TG DTA,IR absorption spectra, X ray diffractometry and TEM as well as its resistivity change and the gas sensitivity varied with temperature were measured in various reducing gas. The results indicate that well crystallized nano sized SnO 2 with size around 15nm can be obtained at annealing temperature 600℃. The activation energy for the growth of nano SnO 2 was calculated to be 26.55kJ.mol 1 when the annealing temperature was higher than 500℃. The measurements also show that there is a peculiar resistance change varied with temperature for nano SnO 2.It has relevance to the increase in surface adsorbed oxygen. The selective detectivities to C 4H 10 and petrol can be increased when ruthenium ion was doped in nano SnO 2 as a catalyst and so do the gas sensitivity to CO,CH 4,H 2 etc. when rhodium ion was doped in.The detection to the several reducing gas can be realized when the temperature ranged from 260℃ to 400℃.
文摘On the basis of analyzing the reliability of the organization’ management chain of the large and medium- sized project in the construction period, the paper studies the factors influencing the reliability of the organi-zation management chain, which, corresponding to four elements of management chain – “Management Loop”, “Management Link”, “Management Chain”, and “Management Network”, can be summarized as project main body, interface management, connection sequence and management model. The paper then re-searches on the specific influencing factors from the above-mentioned four aspects.
基金Support of the National Natural Science Foundation of China (No. 20671028)the Natural Science Foundation of Hebei Province (No. E2006000172)the Postdoctoral Science Foundation of China (No. 2005038511)
文摘The inhibitory effect of phosphate on the crystal grain growth of nanosized titania during high temperature calcination was investigated. Nanosized titanium dioxide powders prepared by hydrolysis of titanium tetrachloride were soaked in phosphate solutions with different concentrations. The obtained powders calcined at various temperatures were characterized by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, and X-ray photoelectronic spectroscopy （XPS）. The grain size of the samples without phosphate treatment increased quickly when calcined at high temperatures, while the grain size of the samples with phosphate modification increased slowly when calcined at the same temperature. This phenomenon implies that phosphate treatment plays an important role in inhibiting the crystal grain growth of titania. The possible mechanism of the inhibition effect of phosphate on titania is discussed.
基金Supported by Key Project of National Social Science Foundation(12xgl007)Fundamental Research Funds for the Central Universities in 2016(swu1609240)
文摘In the context of government appeal of " mass entrepreneurship and innovation",all areas launched the movement of " mass entrepreneurship" and " grassroots entrepreneurship". As parts of vitality of China's market economy,small and medium sized private enterprises become grassroots of market competition in talents,funds,and technologies. This paper combined three levels of entrepreneurial spirit and small and medium sized private enterprises,studied acting mechanism of entrepreneurial spirit,discussed competitive power of small and medium sized private enterprises,and recommended that small and medium sized private enterprises should cultivate core competitive power,adapt to external environment,and create external environment support,to realize sound development.
