Conventionally, an experimentally determined phase diagram requires studies of phase formation at a range of temperatures for each composition, which takes years of effort from multiple research groups. Combinatorial ...Conventionally, an experimentally determined phase diagram requires studies of phase formation at a range of temperatures for each composition, which takes years of effort from multiple research groups. Combinatorial materials chip technology, featuring high-throughput synthesis and characterization, is able to determine the phase diagram of an entire composition spread of a binary or ternary system at a single temperature on one materials library, which, though significantly increasing efficiency, still requires many libraries processed at a series of temperatures in order to complete a phase diagram. In this paper, we propose a "one-chip method" to construct a complete phase diagram by individually synthesizing each pixel step by step with a progressive pulse of energy to heat at different temperatures while monitoring the phase evolution on the pixel in situ in real time. Repeating this process pixel by pixel throughout the whole chip allows the entire binary or ternary phase diagram to be mapped on one chip in a single experiment. The feasibility of this methodology is demonstrated in a study of a Ge-Sb-Te ternary alloy system, on which the amorphouscrystalline phase boundary is determined.展开更多
Springback of sheet metal induced by elastic recovery is one of major defects in sheet metal forming processed. Springback is influenced by many factors including properties of the sheet material and processing condit...Springback of sheet metal induced by elastic recovery is one of major defects in sheet metal forming processed. Springback is influenced by many factors including properties of the sheet material and processing conditions. In this paper, a springback simulation was conducted and comparisons between the results based on different processing variables were illustrated. The discovery of knowledge of the effects of geometry and process parameters on springback from FEM results becomes increasingly important, as the number of numerical simulation has grown exponentially. Data mining is an effective tool to realize knowledge discovery in simulation results. A data-mining algorithm, rough sets theory (RST), was applied to analyze the effects of process parameters on springback in U-bending.展开更多
The recen tly cons true ted cryogenic cylindrical ion trap velocity map imaging spectrometer(CIT-VMI)has been upgraded for coincidence imaging of both ionic and neutral photofragments from photodissociation of ionic s...The recen tly cons true ted cryogenic cylindrical ion trap velocity map imaging spectrometer(CIT-VMI)has been upgraded for coincidence imaging of both ionic and neutral photofragments from photodissociation of ionic species.The prepared ions are cooled down in a homemade cryogenic cylindrical ion trap and then extracted for photodissociation experiments.Wi th the newly designed elec trie fields for extraction and acceleration,the ion beam can be accelerated to more than 4500 eV,which is necessary for velocity imaging of the neutral photofragments by using the position-sensitive imaging detect or.The setup has been tested by the 355 nm pho todissocia tion dynamics of the argon dimer cat ion(Ar2+).From the recorded experimen tal images of both neu tral Ar and ionic Ar+fragments,we interpret velocity resolutions of△v/vu4.6%for neutral fragments,and△v/vul.5%for ionic fragments,respectively.展开更多
Perfect platinum （Pt） nanocubes with high density have been synthesized by controlled reduction of hexachloroplatinic acid in the presence of H2SO4 and HCl, employing a pair of low-resistivity fastened silicon （FS...Perfect platinum （Pt） nanocubes with high density have been synthesized by controlled reduction of hexachloroplatinic acid in the presence of H2SO4 and HCl, employing a pair of low-resistivity fastened silicon （FS） wafers at room temperature. The presence of the additive charges （induced by prior etching of the silicon surface with HF to remove any SiO2 layer） between the interfaces of the FS surface results in a high charge density and facilitates fast deposition of Pt nanoparticles via electroless plating. The charge density, stirring time, and homogeneity of the aqueous solution influenced the geometrical shapes of the Pt nanoparticles. The parameters were finely tuned in order to control the nucleation and growth rates and obtain perfect Pt nanocubes. The perfect Pt nanocubes were single crystalline with exposed {100} facets. Per equivalent Pt surface areas, the perfect Pt nanocubes showed enhanced catalytic activity relative to truncated Pt nanocubes or spherical Pt nanoparticles for the electrooxidation of liquid feed fuels such as methanol and ethanol. Moreover, there a strong correlation was observed between the optical, electrical, thermal, magnetic, and catalytic properties of the perfect Pt nanocubes which should lead to a variety of technological applications of these materials.展开更多
Two-dimensional graphitic carbon nitride（g-C_3N_4） nanosheets（GCNNs） have been considered as an attractive metal-free semiconductor because of their superior catalytic,optical,and electronic properties.However,it ...Two-dimensional graphitic carbon nitride（g-C_3N_4） nanosheets（GCNNs） have been considered as an attractive metal-free semiconductor because of their superior catalytic,optical,and electronic properties.However,it is still challenging to prepare monolayer GCNNs with a reduced lateral size in nanoscale.Herein,a highly efficient ultrasonic technique was used to prepare nanosized monolayer graphitic carbon nitride nanosheets（NMGCNs） with a thickness of around 0.6 nm and an average lateral size of about 55 nm.With a reduced lateral size yet monolayer thickness,NMGCNs show unique photo-responsive properties as compared to both large-sized GCNNs and GCN quantum dots.A dispersion of NMGCNs in water has good stability and exhibits strong blue fluorescence with a high quantum yield of 32%,showing good biocompatibility for cell imaging.Besides,compared to the multilayer GCNNs,NMGCNs show a highly improved photocatalysis under visible light irradiation.Overall,NMGCNs,characterized with monolayer and nanosized lateral dimension,fill the gap between large size（very high aspect ratio） and quantum dot-like counterparts,and show great potential applications as sensors,photo-related and electronic devices.展开更多
This review summarizes the utilization of supported noble metal nanoparticles (such as Au/TiO2, Au/ZrO2, Ag/AgCl) as efficient photo/sono-catalysts for the selective synthesis of chemicals and degradation of environme...This review summarizes the utilization of supported noble metal nanoparticles (such as Au/TiO2, Au/ZrO2, Ag/AgCl) as efficient photo/sono-catalysts for the selective synthesis of chemicals and degradation of environmental pollutants. Supported noble metal nanoparticles could efficiently catalyze the conversion of solar energy into chemical energy. Under UV/visible light irradiation, important chemical transformations such as the oxidation of alcohols to carbonyl compounds, the oxidation of thiol to disulfide, the oxidation of benzene to phenol, and the reduction of nitroaromatic compounds to form aromatic azo compounds, are effectively achieved by supported noble metal nanoparticles. Under ultrasound irradiation, supported noble metal nanoparticles could efficiently catalyze the production of hydrogen from water. Moreover, various pollutants, including aldehydes, alcohols, acids, phenolic compounds, and dyes, can be effectively decomposed over supported noble metal nanoparticles under UV/visible light irradiation. Under ultrasound irradiation, pollutant molecules can also be completely degraded with supported noble metal nanoparticles as catalysts.展开更多
基金supported in part by National High Technology Research and Development Program (2015AA034204)the National Natural Science Foundation of China (51472044)
文摘Conventionally, an experimentally determined phase diagram requires studies of phase formation at a range of temperatures for each composition, which takes years of effort from multiple research groups. Combinatorial materials chip technology, featuring high-throughput synthesis and characterization, is able to determine the phase diagram of an entire composition spread of a binary or ternary system at a single temperature on one materials library, which, though significantly increasing efficiency, still requires many libraries processed at a series of temperatures in order to complete a phase diagram. In this paper, we propose a "one-chip method" to construct a complete phase diagram by individually synthesizing each pixel step by step with a progressive pulse of energy to heat at different temperatures while monitoring the phase evolution on the pixel in situ in real time. Repeating this process pixel by pixel throughout the whole chip allows the entire binary or ternary phase diagram to be mapped on one chip in a single experiment. The feasibility of this methodology is demonstrated in a study of a Ge-Sb-Te ternary alloy system, on which the amorphouscrystalline phase boundary is determined.
基金the Shanghai Post-Phosphor Plan ( No.0 1QMH14 11)
文摘Springback of sheet metal induced by elastic recovery is one of major defects in sheet metal forming processed. Springback is influenced by many factors including properties of the sheet material and processing conditions. In this paper, a springback simulation was conducted and comparisons between the results based on different processing variables were illustrated. The discovery of knowledge of the effects of geometry and process parameters on springback from FEM results becomes increasingly important, as the number of numerical simulation has grown exponentially. Data mining is an effective tool to realize knowledge discovery in simulation results. A data-mining algorithm, rough sets theory (RST), was applied to analyze the effects of process parameters on springback in U-bending.
基金This work was supported by the National Key R&D Program of China(No.2017YFA0303502)the National Natural Science Foundation of China(No.21773221 and No.21827804)the Fundamental Research Funds for the Central Universities of China(No.WK2340000078).
文摘The recen tly cons true ted cryogenic cylindrical ion trap velocity map imaging spectrometer(CIT-VMI)has been upgraded for coincidence imaging of both ionic and neutral photofragments from photodissociation of ionic species.The prepared ions are cooled down in a homemade cryogenic cylindrical ion trap and then extracted for photodissociation experiments.Wi th the newly designed elec trie fields for extraction and acceleration,the ion beam can be accelerated to more than 4500 eV,which is necessary for velocity imaging of the neutral photofragments by using the position-sensitive imaging detect or.The setup has been tested by the 355 nm pho todissocia tion dynamics of the argon dimer cat ion(Ar2+).From the recorded experimen tal images of both neu tral Ar and ionic Ar+fragments,we interpret velocity resolutions of△v/vu4.6%for neutral fragments,and△v/vul.5%for ionic fragments,respectively.
文摘Perfect platinum （Pt） nanocubes with high density have been synthesized by controlled reduction of hexachloroplatinic acid in the presence of H2SO4 and HCl, employing a pair of low-resistivity fastened silicon （FS） wafers at room temperature. The presence of the additive charges （induced by prior etching of the silicon surface with HF to remove any SiO2 layer） between the interfaces of the FS surface results in a high charge density and facilitates fast deposition of Pt nanoparticles via electroless plating. The charge density, stirring time, and homogeneity of the aqueous solution influenced the geometrical shapes of the Pt nanoparticles. The parameters were finely tuned in order to control the nucleation and growth rates and obtain perfect Pt nanocubes. The perfect Pt nanocubes were single crystalline with exposed {100} facets. Per equivalent Pt surface areas, the perfect Pt nanocubes showed enhanced catalytic activity relative to truncated Pt nanocubes or spherical Pt nanoparticles for the electrooxidation of liquid feed fuels such as methanol and ethanol. Moreover, there a strong correlation was observed between the optical, electrical, thermal, magnetic, and catalytic properties of the perfect Pt nanocubes which should lead to a variety of technological applications of these materials.
基金supported by the National Basic Research Program of China(2014CB932400)the National Natural Science Foundation of China(51525204 and 51302274)+1 种基金Shenzhen Basic Research Project(ZDSYS20140509172959981)the Key Laboratory of Advanced Materials of Ministry of Education(2016AML02)
文摘Two-dimensional graphitic carbon nitride（g-C_3N_4） nanosheets（GCNNs） have been considered as an attractive metal-free semiconductor because of their superior catalytic,optical,and electronic properties.However,it is still challenging to prepare monolayer GCNNs with a reduced lateral size in nanoscale.Herein,a highly efficient ultrasonic technique was used to prepare nanosized monolayer graphitic carbon nitride nanosheets（NMGCNs） with a thickness of around 0.6 nm and an average lateral size of about 55 nm.With a reduced lateral size yet monolayer thickness,NMGCNs show unique photo-responsive properties as compared to both large-sized GCNNs and GCN quantum dots.A dispersion of NMGCNs in water has good stability and exhibits strong blue fluorescence with a high quantum yield of 32%,showing good biocompatibility for cell imaging.Besides,compared to the multilayer GCNNs,NMGCNs show a highly improved photocatalysis under visible light irradiation.Overall,NMGCNs,characterized with monolayer and nanosized lateral dimension,fill the gap between large size（very high aspect ratio） and quantum dot-like counterparts,and show great potential applications as sensors,photo-related and electronic devices.
文摘This review summarizes the utilization of supported noble metal nanoparticles (such as Au/TiO2, Au/ZrO2, Ag/AgCl) as efficient photo/sono-catalysts for the selective synthesis of chemicals and degradation of environmental pollutants. Supported noble metal nanoparticles could efficiently catalyze the conversion of solar energy into chemical energy. Under UV/visible light irradiation, important chemical transformations such as the oxidation of alcohols to carbonyl compounds, the oxidation of thiol to disulfide, the oxidation of benzene to phenol, and the reduction of nitroaromatic compounds to form aromatic azo compounds, are effectively achieved by supported noble metal nanoparticles. Under ultrasound irradiation, supported noble metal nanoparticles could efficiently catalyze the production of hydrogen from water. Moreover, various pollutants, including aldehydes, alcohols, acids, phenolic compounds, and dyes, can be effectively decomposed over supported noble metal nanoparticles under UV/visible light irradiation. Under ultrasound irradiation, pollutant molecules can also be completely degraded with supported noble metal nanoparticles as catalysts.
