Water purification systems based on transition metal dichalcogenides face significant challenges,including lack of reactivity under dark conditions,scarcity of catalytically active sites,and rapid recombination of pho...Water purification systems based on transition metal dichalcogenides face significant challenges,including lack of reactivity under dark conditions,scarcity of catalytically active sites,and rapid recombination of photogenerated charge carriers.Simultaneously increasing the number of active sites and improving charge separation efficiency has proven difficult.In this study,we present a novel approach combining molybdenum(Mo) monoatomic doping and size engineering to produce a series of Mo-ReS_(2) quantum dots(MR QDs) with controllable dimensions.High-resolution structural characterization,first-principle calculations,and piezo force microscopy reveal that Mo monoatomic doping enhances the lattice asymmetry,thereby improving the piezoelectric properties.The resulting piezoelectric polarization and the generated built-in electric field significantly improve charge separation efficiency,leading to optimized photocatalytic performance.Additionally,the doping strategy increases the number of active sites and improves the adsorption of intermediate radicals,substantially boosting photo-sterilization efficiency.Our results demonstrate the elimination of 99.95% of Escherichia coli and 100.00% of Staphylococcus aureus within 30 min.Furthermore,we developed a self-purification system simulating water drainage,utilizing low-frequency water streams to trigger the piezoelectric behavior of MR QDs,achieving piezoelectric synergistic photodegradation.This innovative approach provides a more environmentally friendly and economical method for water self-purification,paving the way for advanced water treatment technologies.展开更多
The adsorptive separation of C_(2)H_(4)and C_(2)H_(6),as an alternative to distillation units consuming high energy,is a promising yet challenging research.The great similarity in the molecular size of C_(2)H_(4)and C...The adsorptive separation of C_(2)H_(4)and C_(2)H_(6),as an alternative to distillation units consuming high energy,is a promising yet challenging research.The great similarity in the molecular size of C_(2)H_(4)and C_(2)H_(6)brings challenges to the regulation of adsorbents to realize efficient dynamic separation.Herein,we reported the enhancement of the kinetic separation of C_(2)H_(4)/C_(2)H_(6)by controlling the crystal size of ZnAtzPO_(4)(Atz=3-amino-1,2,4-triazole)to amplify the diffusion difference of C_(2)H_(4)and C_(2)H_(6).Through adjusting the synthesis temperature,reactant concentration,and ligands/metal ions molar ratio,ZnAtzPO4 crystals with different sizes were obtained.Both single-component kinetic adsorption tests and binary-component dynamic breakthrough experiments confirmed the enhancement of the dynamic separation of C_(2)H_(4)/C_(2)H_(6)with the increase in the crystal size of ZnAtzPO_(4).The separation selectivity of C_(2)H_(4)/C_(2)H_(6)increased from 1.3 to 98.5 with the increase in the crystal size of ZnAtzPO_(4).This work demonstrated the role of morphology and size control of adsorbent crystals in the improvement of the C_(2)H_(4)/C_(2)H_(6)kinetic separation performance.展开更多
Sn3.5Ag （mass fraction, %） nanoparticles were synthesized by an improved chemical reduction method at room temperature. 1,10-phenanthroline and sodium borohydride were selected as the surfactant and reducing agent, ...Sn3.5Ag （mass fraction, %） nanoparticles were synthesized by an improved chemical reduction method at room temperature. 1,10-phenanthroline and sodium borohydride were selected as the surfactant and reducing agent, respectively. It was found that no obvious oxidation of the synthesized nanoparticles was traced by X-ray diffraction. In addition, the results show that the density of primary particles decreases with decreasing the addition rate of the reducing agent. Moreover, the slight particle agglomeration and slow secondary particle growth can result in small-sized nanoparticles. Meanwhile, the effect of surfactant concentration on the particle size can effectively be controlled when the reducing agent is added into the precursor at an appropriate rate. In summary, the capping effect caused by the surfactant molecules coordinating with the nanoclusters will restrict the growth of the nanoparticles. The larger the mass ratio of the surfactant to the precursor is, the smaller the particle size is.展开更多
To investigate the possibility of substituting the mechanical stirring system with electromagnetic stirring (EMS) system for aluminum rheo die-casting, the EMS under the different stirring cooling conditions was carri...To investigate the possibility of substituting the mechanical stirring system with electromagnetic stirring (EMS) system for aluminum rheo die-casting, the EMS under the different stirring cooling conditions was carried out. It was found that in the early period of solidification, the dendrite breakages led to a fine primary phase. When dendrites grew coarsely, the effect of ripening on grain size overwhelmed that of dendrite breakage. It was also found that the high cooling rate favored large nucleation rate, and led to a fine primary phase. But high cooling rate also made the growth rate of the dendrite arm, which prevented the dendrite arm from being sheared off. Therefore there were a suitable stirring time and suitable cooling rate to obtain the best rheo die-casting structure. Qualified semisolid A356 aluminum alloy was successfully manufactured with short time EMS.展开更多
How cells accomplish cell size homeostasis is a fascinating topic, and several cell size regulation mechanisms were proposed: timer, sizer, and adder. Recently the adder model has received a great deal of attention. A...How cells accomplish cell size homeostasis is a fascinating topic, and several cell size regulation mechanisms were proposed: timer, sizer, and adder. Recently the adder model has received a great deal of attention. Adder property was also found in the DNA replication cycle. This paper aims to explain the adder phenomenon both in the division-centric picture and replication-centric picture at the molecular level. We established a self-replication model, and the system reached a steady state quickly based on evolution rules. We collected tens of thousands of cells in the same trajectory and calculated the Pearson correlation coefficient between biological variables to decide which regulatory mechanism was adopted by cells. Our simulation results confirmed the double-adder mechanism. Chromosome replication initiation and cell division control are independent and regulated by respective proteins.Cell size homeostasis originates from division control and has nothing to do with replication initiation control. At a slow growth rate, the deviation from adder toward sizer comes from a significant division protein degradation rate when division protein is auto-inhibited. Our results indicated the two necessary conditions in the double-adder mechanism: one is balanced biosynthesis, and the other is that there is a protein trigger threshold to inspire DNA replication initiation and cell division. Our results give insight to the regulatory mechanism of cell size and instructive to synthetic biology.展开更多
With photographing and experiments, this paper divides the cocoon layers into three categories according to their colors, establishes three-color membership function based on fuzzy mathematics, constructs fuzzy sets w...With photographing and experiments, this paper divides the cocoon layers into three categories according to their colors, establishes three-color membership function based on fuzzy mathematics, constructs fuzzy sets which satisfy the range of size control by using the ordinary set and attached frequency of threecolor cocoons combination, then achieves the ordinary sets of range of size control by choosing λ-cut. Under these ordinary sets, each end does duality relative level, then sets up relative matrix and overall sequence and finds the membership function to judge whether the size control is mormal.展开更多
We develop error-control based time integration algorithms for compressible fluid dynam-ics(CFD)applications and show that they are efficient and robust in both the accuracy-limited and stability-limited regime.Focusi...We develop error-control based time integration algorithms for compressible fluid dynam-ics(CFD)applications and show that they are efficient and robust in both the accuracy-limited and stability-limited regime.Focusing on discontinuous spectral element semidis-cretizations,we design new controllers for existing methods and for some new embedded Runge-Kutta pairs.We demonstrate the importance of choosing adequate controller parameters and provide a means to obtain these in practice.We compare a wide range of error-control-based methods,along with the common approach in which step size con-trol is based on the Courant-Friedrichs-Lewy(CFL)number.The optimized methods give improved performance and naturally adopt a step size close to the maximum stable CFL number at loose tolerances,while additionally providing control of the temporal error at tighter tolerances.The numerical examples include challenging industrial CFD applications.展开更多
This paper sets up a mathematical model of size variation to derive theobjective function, and constructs the constrained conditions In accordance withtheories of the raw silk production process and probability. On th...This paper sets up a mathematical model of size variation to derive theobjective function, and constructs the constrained conditions In accordance withtheories of the raw silk production process and probability. On the above basis,the optimal feasible solutions to the parameters of different types of size controlsystem are searched out.展开更多
We study a temporal step size control of explicit Runge-Kutta(RK)methods for com-pressible computational fuid dynamics(CFD),including the Navier-Stokes equations and hyperbolic systems of conservation laws such as the...We study a temporal step size control of explicit Runge-Kutta(RK)methods for com-pressible computational fuid dynamics(CFD),including the Navier-Stokes equations and hyperbolic systems of conservation laws such as the Euler equations.We demonstrate that error-based approaches are convenient in a wide range of applications and compare them to more classical step size control based on a Courant-Friedrichs-Lewy(CFL)number.Our numerical examples show that the error-based step size control is easy to use,robust,and efcient,e.g.,for(initial)transient periods,complex geometries,nonlinear shock captur-ing approaches,and schemes that use nonlinear entropy projections.We demonstrate these properties for problems ranging from well-understood academic test cases to industrially relevant large-scale computations with two disjoint code bases,the open source Julia pack-ages Trixi.jl with OrdinaryDiffEq.jl and the C/Fortran code SSDC based on PETSc.展开更多
Quasi-two dimensional(2D)perovskites have emerged as a promising class of materials due to their remarkable photoluminescence efficiency,which stems from their exceptionally high exciton binding energies.The spatial c...Quasi-two dimensional(2D)perovskites have emerged as a promising class of materials due to their remarkable photoluminescence efficiency,which stems from their exceptionally high exciton binding energies.The spatial confinement of excitons within smaller grain sizes could enhance the formation of biexcitons leading to higher radiative recombination efficiency.However,the synthesis of high-quality quasi-2D perovskite thin films with controllable grain sizes remains a challenging task.In this study,we present a facile method for achieving quasi-2D perovskite thin films with controllable grain sizes ranging from 500 to 900 nm.This is accomplished by intermediate phase engineering during the film fabrication process.Our results demonstrate that quasi-2D perovskite films with smaller grain sizes exhibit more efficient bound exciton generation and a reduced stimulated emission threshold down to 15.89µJ cm^(−2).Furthermore,femtosecond transient absorption measurements reveal that the decay time of bound excitons is shorter in quasi-2D perovskites with smaller grain sizes compared to that of those with larger grains at the same pump density,which is 230.5 ps.This observation suggests a more efficient exciton recombination process in the smaller grain size regime.Our findings would offer a promising approach for the development of efficient bound exciton lasers.展开更多
Controllable construction of organic heterostructures is key to developing supramolecular materials with sophisticated functions.Herein,block heterostructures with controllable shape and dimension have been successful...Controllable construction of organic heterostructures is key to developing supramolecular materials with sophisticated functions.Herein,block heterostructures with controllable shape and dimension have been successfully constructed from one molecular pair of Ir(Ⅲ)complexes 1 and 2 in H_(2)O/CH_(3)CN.Different volume ratios of H_(2)O/CH_(3)CN led to controllable morphologies of assemblies 1 from nanofibers(1NF)to nanosheets(1NS).Through reasonable experimental design,both 1NF and 1NS could be used as seeds to trigger the heterogeneous nucleation-elongation of 2.Finally,unprecedented dual control on the length and width of supramolecular block copolymers from the same monomer pair was realized smoothly.The corresponding heterogeneous nucleation-elongation process was confirmed by time-dependent UV–vis absorption spectra and emission spectra.The components of each segment of the fibrous and sheet-like block copolymers were identified by TEM,SEM,and CLSM.The results reveal that the previously unappreciated solvation effect can serve as a powerful tool to control the morphologies of heterostructures.展开更多
The small and scattered enterprise pattern in the county economy has formed numerous sporadic pollution sources, hindering the centralized treatment of the water environment, increasing the cost and difficulty of trea...The small and scattered enterprise pattern in the county economy has formed numerous sporadic pollution sources, hindering the centralized treatment of the water environment, increasing the cost and difficulty of treatment. How enterprises can make reasonable decisions on their water environment behavior based on the external environment and their own factors is of great significance for scientifically and effectively designing water environment regulation mechanisms. Based on optimal control theory, this study investigates the design of contractual mechanisms for water environmental regulation for small and medium-sized enterprises. The enterprise is regarded as an independent economic entity that can adopt optimal control strategies to maximize its own interests. Based on the participation of multiple subjects including the government, enterprises, and the public, an optimal control strategy model for enterprises under contractual water environmental regulation is constructed using optimal control theory, and a method for calculating the amount of unit pollutant penalties is derived. The water pollutant treatment cost data of a paper company is selected to conduct empirical numerical analysis on the model. The results show that the increase in the probability of government regulation and public participation, as well as the decrease in local government protection for enterprises, can achieve the same regulatory effect while reducing the number of administrative penalties per unit. Finally, the implementation process of contractual water environmental regulation for small and medium-sized enterprises is designed.展开更多
Controlling the size of SBA-15 can be beneficial for exploiting CMK-3, which has excellent structural parameters, for better performance in adsorption and/or catalytic processes. In this study, the width of freestandi...Controlling the size of SBA-15 can be beneficial for exploiting CMK-3, which has excellent structural parameters, for better performance in adsorption and/or catalytic processes. In this study, the width of freestanding SBA-15 rods was readily and successfully regulated by simply altering the stirring power during the synthesis. A higher stirring rate produced SBA-15 rods with larger width. Then, the size of the CMK-3 rods was adjusted by duplication of the different- sized SBA-15. The results show that the larger sized CMK-3 has higher specific surface area and pore volume, which led to a higher adsorption capacity and a faster adsorption rate. It is believed that the synthetic method reported here is powerful for developing better mesoporous carbon for application in water purification and catalysis.展开更多
Nickel nanoparticles （〈10 nm） were success fully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly vinylpyrrolidone （PVP） system. The effects of three fac tors, s...Nickel nanoparticles （〈10 nm） were success fully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly vinylpyrrolidone （PVP） system. The effects of three fac tors, such as the concentration of the nickel ions, the time of reaction, and the amount of PVP （surfactant）, were discussed. The possible growth process of the particles and optimum reactive conditions was also investigated. The result of transmission electron microscopy （TEM） reveals that these nickel nanoparticles are spherical. The average diameter could be controlled as 25 nm under selected conditions. Highresolution TEM and energydispersive spectroscopy results indicates that the nickel nanoparticles are pure. The UVvisible light absorption spectrum shows that the peaks of nickel nanoparticles moves toward the short wavelength along with the decrease of sizes.展开更多
Calcium carbonate, the main component of lime, has been widely used in industry due to its stability and economy. Calcium carbonate has three types of crystalline polymorphism, calcite, aragonite and vaterite, each wi...Calcium carbonate, the main component of lime, has been widely used in industry due to its stability and economy. Calcium carbonate has three types of crystalline polymorphism, calcite, aragonite and vaterite, each with different properties. Therefore, the control of crystal polymorphism is required for industrial applications. In addition, the control of crystal size and shape is similarly required for different applications. In this study, the effect of SrCO<sub>3</sub> on the size control of fine aragonite-type calcium carbonate crystals by uniform urea precipitation and the effect of SrCO<sub>3</sub> addition was investigated by adding solid strontium carbonate and dissolved strontium carbonate. The addition of solid strontium carbonate affected the crystal polymorphism and size of the calcium carbonate produced, depending on the properties of the solid particles and the amount of SrCO<sub>3</sub> added. Experiments on the addition of dissolved SrCO<sub>3</sub> showed that the supersaturation formation rate could be controlled to control the crystal polymorphism.展开更多
Near-monodisperse NaYF4：Yb/Er nanoparticles（NPs） with controlled size, phases（α,β） and shapes（sphere, and hexagonal plate） were synthesized by adjusting the NaF to RE（RE = Y, Yb, Er） ratios, the reaction te...Near-monodisperse NaYF4：Yb/Er nanoparticles（NPs） with controlled size, phases（α,β） and shapes（sphere, and hexagonal plate） were synthesized by adjusting the NaF to RE（RE = Y, Yb, Er） ratios, the reaction temperature and time in the hot surfactant solutions（oleic acid, 1-octadecene） from the improved one-pot thermal decomposition metal trifluoroacetate, and the precursors were prepared via hydrothermal route. The growth kinetics of β-NaYF4 NPs includes several stages： nucleation, growth of aNaYF4, Ostwald ripening, size shrinkage and growth. The results prove that the temperatures are preferred to the phase transformation compared with the NaF content when other experimental conditions are unchanged. Our work will further facilitate the comprehension of the nucleation and growth mechanisms of the NPs, and provide guidance for their controlled synthesis.展开更多
A good method of synthesizing Ti_(3)C_(2)T_(x)(MXene)is critical for ensuring its success in practical applications,e.g.,electromagnetic interference shielding,electrochemical energy storage,catalysis,sensors,and biom...A good method of synthesizing Ti_(3)C_(2)T_(x)(MXene)is critical for ensuring its success in practical applications,e.g.,electromagnetic interference shielding,electrochemical energy storage,catalysis,sensors,and biomedicine.The main concerns focus on the moderation of the approach,yield,and product quality.Herein,a modified approach,organic solvent-assisted intercalation and collection,was developed to prepare Ti_(3)C_(2)T_(x) flakes.The new approach simultaneously solves all the concerns,featuring a low requirement for facility(centrifugation speed<4000 rpm in whole process),gram-level preparation with remarkable yield(46.3%),a good electrical conductivity(8672 S cm^(−1)),an outstanding capacitive performance(352 F g^(−1)),and easy control over the dimension of Ti_(3)C_(2)T_(x) flakes(0.47–4.60μm^(2)).This approach not only gives a superb example for the synthesis of other MXene materials in laboratory,but sheds new light for the future mass production of Ti_(3)C_(2)T_(x) MXene.展开更多
A facile approach was developed for the synthesis of polycrystalline palladium nanoparticles(Pd NPs)by using tannic acid(TA) as green reagent and stabilizer in a 30 ℃ water bath. The size of Pd NPs can be tuned in a ...A facile approach was developed for the synthesis of polycrystalline palladium nanoparticles(Pd NPs)by using tannic acid(TA) as green reagent and stabilizer in a 30 ℃ water bath. The size of Pd NPs can be tuned in a range of 10–60 nm simply by adjusting the concentration of Pd precursor. The catalytic activity and stability of the as-obtained Pd NPs toward formic acid oxidation were analyzed. It is found that these Pd NPs with different sizes exhibit size-dependent and enhanced formic acid oxidation performance compared to the commercial Pd black catalyst. It should be noted that the Pd catalysts with an average size of 24 nm demonstrate the best catalytic activity and stability among the other prepared Pd NPs, which can be ascribed to its larger electrochemical surface area(ECSA)and polycrystalline structure with defects.展开更多
The sheet size of a graphene oxide （GO） can greatly influence its electrical, optical, mechanical, electrochemical and catalytic property. It is a key challenge to how to control the sheet size during its preparatio...The sheet size of a graphene oxide （GO） can greatly influence its electrical, optical, mechanical, electrochemical and catalytic property. It is a key challenge to how to control the sheet size during its preparation in different application fields. According to our previous theoretical calculations of the effect of temperature on the oxidation process of graphene, we use Hummers method to prepare GOs with different sheet sizes by simply controlling the temperature condition in the process of the oxidation reaction of potassium permanganate （KMnO4） with graphene and the dilution process with deionized water. The results detected by transmission electron microscopy （TEM） and atomic force microscopy （AFM） show that the average sizes of GO sheets prepared at different temperatures are about 1 μm and 7 μm respectively. The ultraviolet-visible spectroscopy （UV-vis） shows that lower temperature can lead to smaller oxidation degrees of GO and less oxygen functional groups on the surface. In addition, we prepare GO membranes to test their mechanical strengths by ultrasonic waves, and we find that the strengths of the GO membranes prepared under low temperatures are considerably higher than those prepared under high temperatures, showing the high mechanical strengths of larger GO sheets. Our experimental results testify our previous theoretical calculations. Compared with the traditional centrifugal separation and chemical cutting method, the preparation process of GO by temperature control is simple and low-cost and also enables large-size synthesis. These findings develop a new method to control GO sheet sizes for large-scale potential applications.展开更多
A 3-dimensional(3D)micromagnetic model combined with Fast Fourier Transform(FFT)method was built up to study the writability in the L1_(0)FePt perpendicular medium.The effects of controllable grain size distributions ...A 3-dimensional(3D)micromagnetic model combined with Fast Fourier Transform(FFT)method was built up to study the writability in the L1_(0)FePt perpendicular medium.The effects of controllable grain size distributions were studied by grain growth simulation.It is found that the cross-track-averaged magnetization changes little between the L1_(0)FePt medium with uniform or non-uniform grain size distribution.展开更多
基金financially supported by the National Natural Science Foundation of China (No.52071146)Guangdong Provincial Natural Science Foundation (No.2023A1515010989)the Science and Technology Projects in Guangzhou (No.202201000008)。
文摘Water purification systems based on transition metal dichalcogenides face significant challenges,including lack of reactivity under dark conditions,scarcity of catalytically active sites,and rapid recombination of photogenerated charge carriers.Simultaneously increasing the number of active sites and improving charge separation efficiency has proven difficult.In this study,we present a novel approach combining molybdenum(Mo) monoatomic doping and size engineering to produce a series of Mo-ReS_(2) quantum dots(MR QDs) with controllable dimensions.High-resolution structural characterization,first-principle calculations,and piezo force microscopy reveal that Mo monoatomic doping enhances the lattice asymmetry,thereby improving the piezoelectric properties.The resulting piezoelectric polarization and the generated built-in electric field significantly improve charge separation efficiency,leading to optimized photocatalytic performance.Additionally,the doping strategy increases the number of active sites and improves the adsorption of intermediate radicals,substantially boosting photo-sterilization efficiency.Our results demonstrate the elimination of 99.95% of Escherichia coli and 100.00% of Staphylococcus aureus within 30 min.Furthermore,we developed a self-purification system simulating water drainage,utilizing low-frequency water streams to trigger the piezoelectric behavior of MR QDs,achieving piezoelectric synergistic photodegradation.This innovative approach provides a more environmentally friendly and economical method for water self-purification,paving the way for advanced water treatment technologies.
基金supported by the National Key Research and Development Program of China(2022YFB3806800)the National Natural Science Foundation of China(22122811,22008209)the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2021SZ-TD008).
文摘The adsorptive separation of C_(2)H_(4)and C_(2)H_(6),as an alternative to distillation units consuming high energy,is a promising yet challenging research.The great similarity in the molecular size of C_(2)H_(4)and C_(2)H_(6)brings challenges to the regulation of adsorbents to realize efficient dynamic separation.Herein,we reported the enhancement of the kinetic separation of C_(2)H_(4)/C_(2)H_(6)by controlling the crystal size of ZnAtzPO_(4)(Atz=3-amino-1,2,4-triazole)to amplify the diffusion difference of C_(2)H_(4)and C_(2)H_(6).Through adjusting the synthesis temperature,reactant concentration,and ligands/metal ions molar ratio,ZnAtzPO4 crystals with different sizes were obtained.Both single-component kinetic adsorption tests and binary-component dynamic breakthrough experiments confirmed the enhancement of the dynamic separation of C_(2)H_(4)/C_(2)H_(6)with the increase in the crystal size of ZnAtzPO_(4).The separation selectivity of C_(2)H_(4)/C_(2)H_(6)increased from 1.3 to 98.5 with the increase in the crystal size of ZnAtzPO_(4).This work demonstrated the role of morphology and size control of adsorbent crystals in the improvement of the C_(2)H_(4)/C_(2)H_(6)kinetic separation performance.
基金Projects(50971086,51171105)supported by the National Natural Science Foundation of China
文摘Sn3.5Ag （mass fraction, %） nanoparticles were synthesized by an improved chemical reduction method at room temperature. 1,10-phenanthroline and sodium borohydride were selected as the surfactant and reducing agent, respectively. It was found that no obvious oxidation of the synthesized nanoparticles was traced by X-ray diffraction. In addition, the results show that the density of primary particles decreases with decreasing the addition rate of the reducing agent. Moreover, the slight particle agglomeration and slow secondary particle growth can result in small-sized nanoparticles. Meanwhile, the effect of surfactant concentration on the particle size can effectively be controlled when the reducing agent is added into the precursor at an appropriate rate. In summary, the capping effect caused by the surfactant molecules coordinating with the nanoclusters will restrict the growth of the nanoparticles. The larger the mass ratio of the surfactant to the precursor is, the smaller the particle size is.
文摘To investigate the possibility of substituting the mechanical stirring system with electromagnetic stirring (EMS) system for aluminum rheo die-casting, the EMS under the different stirring cooling conditions was carried out. It was found that in the early period of solidification, the dendrite breakages led to a fine primary phase. When dendrites grew coarsely, the effect of ripening on grain size overwhelmed that of dendrite breakage. It was also found that the high cooling rate favored large nucleation rate, and led to a fine primary phase. But high cooling rate also made the growth rate of the dendrite arm, which prevented the dendrite arm from being sheared off. Therefore there were a suitable stirring time and suitable cooling rate to obtain the best rheo die-casting structure. Qualified semisolid A356 aluminum alloy was successfully manufactured with short time EMS.
文摘How cells accomplish cell size homeostasis is a fascinating topic, and several cell size regulation mechanisms were proposed: timer, sizer, and adder. Recently the adder model has received a great deal of attention. Adder property was also found in the DNA replication cycle. This paper aims to explain the adder phenomenon both in the division-centric picture and replication-centric picture at the molecular level. We established a self-replication model, and the system reached a steady state quickly based on evolution rules. We collected tens of thousands of cells in the same trajectory and calculated the Pearson correlation coefficient between biological variables to decide which regulatory mechanism was adopted by cells. Our simulation results confirmed the double-adder mechanism. Chromosome replication initiation and cell division control are independent and regulated by respective proteins.Cell size homeostasis originates from division control and has nothing to do with replication initiation control. At a slow growth rate, the deviation from adder toward sizer comes from a significant division protein degradation rate when division protein is auto-inhibited. Our results indicated the two necessary conditions in the double-adder mechanism: one is balanced biosynthesis, and the other is that there is a protein trigger threshold to inspire DNA replication initiation and cell division. Our results give insight to the regulatory mechanism of cell size and instructive to synthetic biology.
文摘With photographing and experiments, this paper divides the cocoon layers into three categories according to their colors, establishes three-color membership function based on fuzzy mathematics, constructs fuzzy sets which satisfy the range of size control by using the ordinary set and attached frequency of threecolor cocoons combination, then achieves the ordinary sets of range of size control by choosing λ-cut. Under these ordinary sets, each end does duality relative level, then sets up relative matrix and overall sequence and finds the membership function to judge whether the size control is mormal.
基金Open Access funding enabled and organized by Projekt DEAL.
文摘We develop error-control based time integration algorithms for compressible fluid dynam-ics(CFD)applications and show that they are efficient and robust in both the accuracy-limited and stability-limited regime.Focusing on discontinuous spectral element semidis-cretizations,we design new controllers for existing methods and for some new embedded Runge-Kutta pairs.We demonstrate the importance of choosing adequate controller parameters and provide a means to obtain these in practice.We compare a wide range of error-control-based methods,along with the common approach in which step size con-trol is based on the Courant-Friedrichs-Lewy(CFL)number.The optimized methods give improved performance and naturally adopt a step size close to the maximum stable CFL number at loose tolerances,while additionally providing control of the temporal error at tighter tolerances.The numerical examples include challenging industrial CFD applications.
文摘This paper sets up a mathematical model of size variation to derive theobjective function, and constructs the constrained conditions In accordance withtheories of the raw silk production process and probability. On the above basis,the optimal feasible solutions to the parameters of different types of size controlsystem are searched out.
基金Open Access funding enabled and organized by Projekt DEAL.Andrew Winters was funded through Vetenskapsrådet,Sweden Grant Agreement 2020-03642 VR.Some computations were enabled by resources provided by the Swedish National Infrastructure for Computing(SNIC)at Tetralith,par-tially funded by the Swedish Research Council under Grant Agreement No.2018-05973Hugo Guillermo Castro was funded through the award P2021-0004 of King Abdullah University of Science and Technol-ogy.Some of the simulations were enabled by the Supercomputing Laboratory and the Extreme Comput-ing Research Center at King Abdullah University of Science and Technology.Gregor Gassner acknowl-edges funding through the Klaus-Tschira Stiftung via the project“HiFiLab”.Gregor Gassner and Michael Schlottke-Lakemper acknowledge funding from the Deutsche Forschungsgemeinschaft through the research unit“SNuBIC”(DFG-FOR5409).
文摘We study a temporal step size control of explicit Runge-Kutta(RK)methods for com-pressible computational fuid dynamics(CFD),including the Navier-Stokes equations and hyperbolic systems of conservation laws such as the Euler equations.We demonstrate that error-based approaches are convenient in a wide range of applications and compare them to more classical step size control based on a Courant-Friedrichs-Lewy(CFL)number.Our numerical examples show that the error-based step size control is easy to use,robust,and efcient,e.g.,for(initial)transient periods,complex geometries,nonlinear shock captur-ing approaches,and schemes that use nonlinear entropy projections.We demonstrate these properties for problems ranging from well-understood academic test cases to industrially relevant large-scale computations with two disjoint code bases,the open source Julia pack-ages Trixi.jl with OrdinaryDiffEq.jl and the C/Fortran code SSDC based on PETSc.
基金supported by the National Natural Science Foundation of China(U21A20496 and 12104334)the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20230011)+5 种基金the Research Program Supported by ShanxiZheda Institute of Advanced Materials and Chemical Engineering(2022SXTD020)the Central Government Guides Local Funds for Scientific and Technological Development(YDZJSX20231A010)the Natural Science Foundation of Shanxi Province(202203021222102)the State Key Laboratory Program of Quantum Optics and Quantum Optics Devices(KF202306)the support from a research grant(VIL50350)from VILLUM FONDEN,Denmark,the Swedish Research Council(2021-05319)the Swedish foundation of international cooperation in research and higher education(CH2019-8248)。
文摘Quasi-two dimensional(2D)perovskites have emerged as a promising class of materials due to their remarkable photoluminescence efficiency,which stems from their exceptionally high exciton binding energies.The spatial confinement of excitons within smaller grain sizes could enhance the formation of biexcitons leading to higher radiative recombination efficiency.However,the synthesis of high-quality quasi-2D perovskite thin films with controllable grain sizes remains a challenging task.In this study,we present a facile method for achieving quasi-2D perovskite thin films with controllable grain sizes ranging from 500 to 900 nm.This is accomplished by intermediate phase engineering during the film fabrication process.Our results demonstrate that quasi-2D perovskite films with smaller grain sizes exhibit more efficient bound exciton generation and a reduced stimulated emission threshold down to 15.89µJ cm^(−2).Furthermore,femtosecond transient absorption measurements reveal that the decay time of bound excitons is shorter in quasi-2D perovskites with smaller grain sizes compared to that of those with larger grains at the same pump density,which is 230.5 ps.This observation suggests a more efficient exciton recombination process in the smaller grain size regime.Our findings would offer a promising approach for the development of efficient bound exciton lasers.
基金financial support from the National Natural Science Foundation of China(No.21978042)the Fundamental Research Funds for the Central Universities(No.DUT22LAB610)。
文摘Controllable construction of organic heterostructures is key to developing supramolecular materials with sophisticated functions.Herein,block heterostructures with controllable shape and dimension have been successfully constructed from one molecular pair of Ir(Ⅲ)complexes 1 and 2 in H_(2)O/CH_(3)CN.Different volume ratios of H_(2)O/CH_(3)CN led to controllable morphologies of assemblies 1 from nanofibers(1NF)to nanosheets(1NS).Through reasonable experimental design,both 1NF and 1NS could be used as seeds to trigger the heterogeneous nucleation-elongation of 2.Finally,unprecedented dual control on the length and width of supramolecular block copolymers from the same monomer pair was realized smoothly.The corresponding heterogeneous nucleation-elongation process was confirmed by time-dependent UV–vis absorption spectra and emission spectra.The components of each segment of the fibrous and sheet-like block copolymers were identified by TEM,SEM,and CLSM.The results reveal that the previously unappreciated solvation effect can serve as a powerful tool to control the morphologies of heterostructures.
文摘The small and scattered enterprise pattern in the county economy has formed numerous sporadic pollution sources, hindering the centralized treatment of the water environment, increasing the cost and difficulty of treatment. How enterprises can make reasonable decisions on their water environment behavior based on the external environment and their own factors is of great significance for scientifically and effectively designing water environment regulation mechanisms. Based on optimal control theory, this study investigates the design of contractual mechanisms for water environmental regulation for small and medium-sized enterprises. The enterprise is regarded as an independent economic entity that can adopt optimal control strategies to maximize its own interests. Based on the participation of multiple subjects including the government, enterprises, and the public, an optimal control strategy model for enterprises under contractual water environmental regulation is constructed using optimal control theory, and a method for calculating the amount of unit pollutant penalties is derived. The water pollutant treatment cost data of a paper company is selected to conduct empirical numerical analysis on the model. The results show that the increase in the probability of government regulation and public participation, as well as the decrease in local government protection for enterprises, can achieve the same regulatory effect while reducing the number of administrative penalties per unit. Finally, the implementation process of contractual water environmental regulation for small and medium-sized enterprises is designed.
基金This work was supported by the National Natural Science Foundation of China （Nos. 21541005 and 51420105002）, and the Natural Science Foundation of Zhejiang Province （NSFZJ） （No. LY14B010002）.
文摘Controlling the size of SBA-15 can be beneficial for exploiting CMK-3, which has excellent structural parameters, for better performance in adsorption and/or catalytic processes. In this study, the width of freestanding SBA-15 rods was readily and successfully regulated by simply altering the stirring power during the synthesis. A higher stirring rate produced SBA-15 rods with larger width. Then, the size of the CMK-3 rods was adjusted by duplication of the different- sized SBA-15. The results show that the larger sized CMK-3 has higher specific surface area and pore volume, which led to a higher adsorption capacity and a faster adsorption rate. It is believed that the synthetic method reported here is powerful for developing better mesoporous carbon for application in water purification and catalysis.
基金supported by the National Natural Science Foundation of China(Nos.51272025 and 50872011)the National Key Basic Research Development Plan(973 Program)(No.2007CB613608)the New Century Excellent Researcher Award Program from Ministry of Education of China(No.NCET-08-0732)
文摘Nickel nanoparticles （〈10 nm） were success fully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly vinylpyrrolidone （PVP） system. The effects of three fac tors, such as the concentration of the nickel ions, the time of reaction, and the amount of PVP （surfactant）, were discussed. The possible growth process of the particles and optimum reactive conditions was also investigated. The result of transmission electron microscopy （TEM） reveals that these nickel nanoparticles are spherical. The average diameter could be controlled as 25 nm under selected conditions. Highresolution TEM and energydispersive spectroscopy results indicates that the nickel nanoparticles are pure. The UVvisible light absorption spectrum shows that the peaks of nickel nanoparticles moves toward the short wavelength along with the decrease of sizes.
文摘Calcium carbonate, the main component of lime, has been widely used in industry due to its stability and economy. Calcium carbonate has three types of crystalline polymorphism, calcite, aragonite and vaterite, each with different properties. Therefore, the control of crystal polymorphism is required for industrial applications. In addition, the control of crystal size and shape is similarly required for different applications. In this study, the effect of SrCO<sub>3</sub> on the size control of fine aragonite-type calcium carbonate crystals by uniform urea precipitation and the effect of SrCO<sub>3</sub> addition was investigated by adding solid strontium carbonate and dissolved strontium carbonate. The addition of solid strontium carbonate affected the crystal polymorphism and size of the calcium carbonate produced, depending on the properties of the solid particles and the amount of SrCO<sub>3</sub> added. Experiments on the addition of dissolved SrCO<sub>3</sub> showed that the supersaturation formation rate could be controlled to control the crystal polymorphism.
基金Project supported by the National Natural Science Foundation of China(2126016)the Science and Technology Innovation Guidance Project,Inner Mongolia,China(000-21090179)+2 种基金the Talents Project Inner Mongolia(CYYC:5026)the Opened Fund of the State Key Laboratory on integrated Optoelectronics(China IOSKL2013KF08)the Graduate Student Scientific Research Foundation of Inner Mongolia(S20161013505)
文摘Near-monodisperse NaYF4：Yb/Er nanoparticles（NPs） with controlled size, phases（α,β） and shapes（sphere, and hexagonal plate） were synthesized by adjusting the NaF to RE（RE = Y, Yb, Er） ratios, the reaction temperature and time in the hot surfactant solutions（oleic acid, 1-octadecene） from the improved one-pot thermal decomposition metal trifluoroacetate, and the precursors were prepared via hydrothermal route. The growth kinetics of β-NaYF4 NPs includes several stages： nucleation, growth of aNaYF4, Ostwald ripening, size shrinkage and growth. The results prove that the temperatures are preferred to the phase transformation compared with the NaF content when other experimental conditions are unchanged. Our work will further facilitate the comprehension of the nucleation and growth mechanisms of the NPs, and provide guidance for their controlled synthesis.
基金This work was financially supported by National Natural Science Foundation of China(No.51903197)Wuhu and Xidian University special fund for industry-universityresearch cooperation(No.XWYCXY-012020012)+3 种基金Open Fund of Zhijiang Lab(2021MC0AB02)China Postdoctoral Science Foundation(2019TQ02422019M660061XB)the Fundamental Research Funds for the Central Universities(JC2110,JB211305).
文摘A good method of synthesizing Ti_(3)C_(2)T_(x)(MXene)is critical for ensuring its success in practical applications,e.g.,electromagnetic interference shielding,electrochemical energy storage,catalysis,sensors,and biomedicine.The main concerns focus on the moderation of the approach,yield,and product quality.Herein,a modified approach,organic solvent-assisted intercalation and collection,was developed to prepare Ti_(3)C_(2)T_(x) flakes.The new approach simultaneously solves all the concerns,featuring a low requirement for facility(centrifugation speed<4000 rpm in whole process),gram-level preparation with remarkable yield(46.3%),a good electrical conductivity(8672 S cm^(−1)),an outstanding capacitive performance(352 F g^(−1)),and easy control over the dimension of Ti_(3)C_(2)T_(x) flakes(0.47–4.60μm^(2)).This approach not only gives a superb example for the synthesis of other MXene materials in laboratory,but sheds new light for the future mass production of Ti_(3)C_(2)T_(x) MXene.
基金financially supported by the National Natural Science Foundation of China (Nos. 51371119 and 51571151)
文摘A facile approach was developed for the synthesis of polycrystalline palladium nanoparticles(Pd NPs)by using tannic acid(TA) as green reagent and stabilizer in a 30 ℃ water bath. The size of Pd NPs can be tuned in a range of 10–60 nm simply by adjusting the concentration of Pd precursor. The catalytic activity and stability of the as-obtained Pd NPs toward formic acid oxidation were analyzed. It is found that these Pd NPs with different sizes exhibit size-dependent and enhanced formic acid oxidation performance compared to the commercial Pd black catalyst. It should be noted that the Pd catalysts with an average size of 24 nm demonstrate the best catalytic activity and stability among the other prepared Pd NPs, which can be ascribed to its larger electrochemical surface area(ECSA)and polycrystalline structure with defects.
基金supported by the National Natural Science Foundation of China(Grant Nos.41473090,41430644,11675098,41373098,41430644,and 21490585)
文摘The sheet size of a graphene oxide （GO） can greatly influence its electrical, optical, mechanical, electrochemical and catalytic property. It is a key challenge to how to control the sheet size during its preparation in different application fields. According to our previous theoretical calculations of the effect of temperature on the oxidation process of graphene, we use Hummers method to prepare GOs with different sheet sizes by simply controlling the temperature condition in the process of the oxidation reaction of potassium permanganate （KMnO4） with graphene and the dilution process with deionized water. The results detected by transmission electron microscopy （TEM） and atomic force microscopy （AFM） show that the average sizes of GO sheets prepared at different temperatures are about 1 μm and 7 μm respectively. The ultraviolet-visible spectroscopy （UV-vis） shows that lower temperature can lead to smaller oxidation degrees of GO and less oxygen functional groups on the surface. In addition, we prepare GO membranes to test their mechanical strengths by ultrasonic waves, and we find that the strengths of the GO membranes prepared under low temperatures are considerably higher than those prepared under high temperatures, showing the high mechanical strengths of larger GO sheets. Our experimental results testify our previous theoretical calculations. Compared with the traditional centrifugal separation and chemical cutting method, the preparation process of GO by temperature control is simple and low-cost and also enables large-size synthesis. These findings develop a new method to control GO sheet sizes for large-scale potential applications.
文摘A 3-dimensional(3D)micromagnetic model combined with Fast Fourier Transform(FFT)method was built up to study the writability in the L1_(0)FePt perpendicular medium.The effects of controllable grain size distributions were studied by grain growth simulation.It is found that the cross-track-averaged magnetization changes little between the L1_(0)FePt medium with uniform or non-uniform grain size distribution.
