The spatial resolution of a commercial two-dimensional(2D)ionization chamber(IC)array is limited by the size of the individual detector and the center-to-center distance between sensors.For dose distributions with are...The spatial resolution of a commercial two-dimensional(2D)ionization chamber(IC)array is limited by the size of the individual detector and the center-to-center distance between sensors.For dose distributions with areas of steep dose gradients,inter-detector dose values are derived by the interpolation of nearby detector readings in the conventional mathematical interpolation of 2D IC array measurements.This may introduce significant errors,particularly in proton spot scanning radiotherapy.In this study,by combining logfile-based reconstructed dose values and detector measurements with the Laplacian pyramid image blending method,a novel method is proposed to obtain a reformatted dose distribution that provides an improved estimation of the delivered dose distribution with high spatial resolution.Meanwhile,the similarity between the measured original data and the downsampled logfilebased reconstructed dose is regarded as the confidence of the reformatted dose distribution.Furthermore,we quantify the performance benefits of this new approach by directly comparing the reformatted dose distributions with 2D IC array detector mathematically interpolated measurements and original low-resolution measurements.The result shows that this new method is better than the mathematical interpolation and achieves gamma pass rates similar to those of the original low-resolution measurements.The reformatted dose distributions generally yield a confidence exceeding 95%.展开更多
Desulfurization of CaO–Al_(2)O_(3) particles in molten steel was observed in situ using high-temperature confocal scanning laser microscopy.The effects of the aluminum and silicon contents of molten steel on desulfur...Desulfurization of CaO–Al_(2)O_(3) particles in molten steel was observed in situ using high-temperature confocal scanning laser microscopy.The effects of the aluminum and silicon contents of molten steel on desulfurization were analyzed.When the total aluminum content in the steel increased from 6 to 1100 ppm,the CaS content in CaO–Al_(2)O_(3) particles increased from 2.1wt%to 84.84wt%after the reaction for 90 s.Furthermore,when the silicon content in the steel increased from 0.01wt%to 2.20wt%,the CaS content in CaO–Al_(2)O_(3) particles increased from 1.53wt%to 79.01wt%after the reaction for 90 s.This indicates that the increase in the aluminum and silicon contents of the steel promoted the desulfurization of CaO–Al_(2)O_(3) particles.A kinetic model was established to predict the CaO–Al_(2)O_(3) particles composition,and the diffusion coefficient of sulfur in CaO–Al_(2)O_(3) particles was 9.375×10^(−10)m^(2)·s^(−1) at 1600℃,which provided a new method for the calculation of diffusion coefficient.展开更多
Objective:To explore the application effect of digital intraoral scanning impression technique in oral implant restoration for periodontitis patients and analyze its impact on patients’Visual Analogue Scale(VAS)score...Objective:To explore the application effect of digital intraoral scanning impression technique in oral implant restoration for periodontitis patients and analyze its impact on patients’Visual Analogue Scale(VAS)scores.Methods:A total of 80 periodontitis patients who received implant restoration in our hospital from May 2023 to May 2025 were selected as research subjects.They were randomly divided into an observation group and a control group using a random number table method,with 40 cases in each group.The observation group used the digital intraoral scanning impression technique to obtain impressions,while the control group used the traditional silicone rubber impression technique.The impression-taking time,the number of prostheses try-ins,implant survival rate,periodontal health indicators(probing depth,gingival index,bleeding index),and VAS scores(pain during treatment and comfort after restoration)were compared between the two groups.Results:The observation group was superior to the control group in terms of impression-taking time,the number of prostheses try-ins,and implant survival rate(p<0.05).Six months after restoration,the improvement in periodontal health indicators in the observation group was significantly better than that in the control group(p<0.05).In addition,the pain VAS score of the observation group during treatment was lower than that of the control group,and the comfort VAS score after restoration was higher than that of the control group(p<0.05).Conclusion:Digital intraoral scanning impression technology can effectively enhance the efficiency and success rate of implant restoration in periodontitis patients,improve periodontal health,alleviate patients’discomfort during treatment,and increase post-restoration comfort,demonstrating high clinical application value.展开更多
In this review, a group ot two-dimensional （2D） hydrogen-bonded supramolecular networks developed in our laboratory are discussed. Our attention is mainly focused on： （1） recognition of Fe3＋ through twocomponent...In this review, a group ot two-dimensional （2D） hydrogen-bonded supramolecular networks developed in our laboratory are discussed. Our attention is mainly focused on： （1） recognition of Fe3＋ through twocomponent molecular networks; （2） site-selective fabrication of 2D fullerene arrays; and （3） fabrication of the nanoporous structure regulated by photoisomerization reaction process. It is envisioned that special supramolecular nanostructures, through H-bonding interactions, can be constructed or reconstructed to be further investigated toward the research of multi-component systems, molecule recognition, single molecular switches, and host-vip supramolecular chemistry.展开更多
Some theorems of compactly supported non-tensor product form two-dimension Daubechies wavelet were analysed carefully. Compactly supported non-tensor product form two-dimension wavelet was constructed, then non-tensor...Some theorems of compactly supported non-tensor product form two-dimension Daubechies wavelet were analysed carefully. Compactly supported non-tensor product form two-dimension wavelet was constructed, then non-tensor product form two dimension wavelet finite element was used to solve the deflection problem of elastic thin plate. The error order was researched. A numerical example was given at last.展开更多
The adaptive mesh refinement （AMR） method is applied in the 2-D Euler multi-component elasticplastic hydrodynamics code （MEPH2Y）. It is applied on detonation. Firstly, the AMR method is described, including a cons...The adaptive mesh refinement （AMR） method is applied in the 2-D Euler multi-component elasticplastic hydrodynamics code （MEPH2Y）. It is applied on detonation. Firstly, the AMR method is described, including a conservative spatial interpolation, the time integration methodology with the adapitve time increment and an adaptive computational region method. The advantage of AMR technique is exhibited by numerical examples, including the 1-D C-J detonation and the 2-D implosion ignited from a single point. Results show that AMR can promote the computational efficiency, keeping the accuracy in interesting regions.展开更多
The polyacidic character of polyoxometalate(POM)clusters endows high ionic conductivity,making these clusters good candidates for solar and fuel cells.Covalent bonding of clusters to polymer chains creates poly(POM)s ...The polyacidic character of polyoxometalate(POM)clusters endows high ionic conductivity,making these clusters good candidates for solar and fuel cells.Covalent bonding of clusters to polymer chains creates poly(POM)s that are polyelectrolytes with both cluster functions and polymer performance.Thus,solution-processable poly(POM)s are expected to be used as key materials in advanced devices.Further understanding of poly(POM)s will optimize the preparation process and improve device performance.Herein,we report a study of the first linear poly(POM)s by directly visualizing the chains using scanning transmission electron microscopy.Compared with traditional polymers,individual clusters of poly(POM)s can be directly visualized because of the resistance to electron-beam damage and the high contrast of the tungsten POM pendants.Thus,cluster aggregates with diverse shapes were observed.Counting the number of clusters in the aggregates allowed the degree of polymerization and molecular weight distribution to be determined,and studying the aggregate shapes revealed the presence of a curved semirigid chain in solution.Further study of shape diversity revealed that strong interactions between clusters determine the diverse chain shapes formed during solution processing.Fundamental insight is critical to understanding the formation of poly(POM)films from solutions as key functional materials,especially for fuel and solar cells.展开更多
Two-dimensional(2 D) materials provide a platform to exploit the novel physical properties of functional nanodevices.Here, we report on the formation of a new 2 D layered material, a well-ordered monolayer TiTe_2, on ...Two-dimensional(2 D) materials provide a platform to exploit the novel physical properties of functional nanodevices.Here, we report on the formation of a new 2 D layered material, a well-ordered monolayer TiTe_2, on a Au(111) surface by molecular beam epitaxy(MBE). Low-energy electron diffraction(LEED) measurements of the samples indicate that the TiTe_2 film forms(√3 ×√7) superlattice with respect to the Au(111) substrate, which has three different orientations. Scanning tunneling microscopy(STM) measurements clearly show three ordered domains consistent with the LEED patterns.Density functional theory(DFT) calculations further confirm the formation of 2 H-TiTe_2 monolayer on the Au(111) surface with Te as buffer layer. The fabrication of this 2 D layered heterostructure expands 2 D material database, which may bring new physical properties for future applications.展开更多
By considering the effect of suspended solid particles in the ordinary equations for two-dimension inviscid incompressible mixing layer, the Rayleigh equation and the modified Rayleigh equation are obtained. And then,...By considering the effect of suspended solid particles in the ordinary equations for two-dimension inviscid incompressible mixing layer, the Rayleigh equation and the modified Rayleigh equation are obtained. And then, by solving the corresponding eigen-value equations with numerical computational method, the relation curves between perturbation frequency and spacial growth rate of the mixing layer for the varying particle loading, ratio of particle velocity to fluid velocity and Stokes number are got. Sever al important conclusions on the effect of suspended solid particles on unstability of the mixing layer are presented in the end by analyzing all the relation curves.展开更多
The surface quality of fine-grained ZrO2 engineering ceramic were researched using 270# diamond wheel both with and without work-piece two-dimension ultrasonic vibration grinding（WTDUVG）. By AFM images, the surface ...The surface quality of fine-grained ZrO2 engineering ceramic were researched using 270# diamond wheel both with and without work-piece two-dimension ultrasonic vibration grinding（WTDUVG）. By AFM images, the surface topography and the micro structure of the two-dimensional ultrasonic vibration grinding ceramics were especially analyzed. The experimental results indicate that the surface roughness is related to grinding vibration mode and the material removal mechanism. Surface quality of WTDUVG is superior to that of conventional grinding, and it is easy for two-dimensional ultrasonic vibration grinding that material removal mechanism is ductile mode grinding.展开更多
Nanoclusters consisting of a few atoms have attracted a lot of research interests due to their exotic size-dependent properties. Here, well-ordered two-dimensional Sb cluster superlattice was fabricated on Si substrat...Nanoclusters consisting of a few atoms have attracted a lot of research interests due to their exotic size-dependent properties. Here, well-ordered two-dimensional Sb cluster superlattice was fabricated on Si substrate by a two-step method and characterized by scanning tunneling microscopy. High resolution scanning tunneling microscope measurements revealed the fine structures of the Sb clusters, which consist of several Sb atoms ranging from 2 to 7. Furthermore, the electronic structure of the nanocluster displays the quantized energy-level which is due to the single-electron tunneling effects. We believe that the fabrication of Sb cluster superlattice broadens the species of the cluster superlattice and provides a promising candidate to further explore the novel physical and chemical properties of the semimetal nanocluster.展开更多
Pure mesoporous ZrO2 thin film with two-dimensional hexagonal framework mesostructure has been successfully prepared by using a nonionic triblock copolymer as the structure-directing agent and ZrCl4 as the zireonia so...Pure mesoporous ZrO2 thin film with two-dimensional hexagonal framework mesostructure has been successfully prepared by using a nonionic triblock copolymer as the structure-directing agent and ZrCl4 as the zireonia source through evaporation-induced self-assembly approach. The resulting materials were characterized by X-ray diffraction, scanning electron microscope, and nitrogen adsorption ,neasurenlents. The obtained mesoporous ZrO2 thin film has a nanocrystalline inorganic framework （tetragonal zirconia） and narrowly distributed mcsopore size （6. 7 nm in diameter].展开更多
As a kind of subculture, The two-dimensional culture came of age during the 1970s in Japan and spread to China in the 1980s. In China, the culture has become an important economic force and social capital get more and...As a kind of subculture, The two-dimensional culture came of age during the 1970s in Japan and spread to China in the 1980s. In China, the culture has become an important economic force and social capital get more and more attention to it as well. This paper mainly discusses the origin and development of the two-dimensional clothing, and summed up the inherent characteristics and the internal developing law of it, furthermore, on the stage of current situation of two-dimensional economy this paper will conclude the development trend of next days.展开更多
The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are revi...The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are reviewed and summarized,particularly the col-lision of various inclusions,dissolution of inclusions in liquid slag,and reactions between inclusions and steel.Solid inclusions exhibited a high collision tendency,whereas pure liquid inclusions exhibited minimal collisions because of the small attraction force induced by their<90°contact angle with molten steel.The collision of complex inclusions in molten steel was not included in the scope of this study and should be evaluated in future studies.Higher CaO/Al_(2)O_(3)and CaO/SiO_(2)ratios in liquid slag promoted the dissolution of Al_(2)O_(3)-based in-clusions.The formation of solid phases in the slag should be prevented to improve dissolution of inclusions.To accurately simulate the dissolution of inclusions in liquid slag,in-situ observation of the dissolution of inclusions at the steel-slag interface is necessary.Using a combination of CSLM and scanning electron microscopy-energy dispersive spectroscopy,the composition and morphological evolution of the inclusions during their modification by the dissolved elements in steel were observed and analyzed.Although the in-situ observa-tion of MnS and TiN precipitations has been widely studied,the in-situ observation of the evolution of oxide inclusions in steel during so-lidification and heating processes has rarely been reported.The effects of temperature,heating and cooling rates,and inclusion character-istics on the formation of acicular ferrites(AFs)have been widely studied.At a cooling rate of 3-5 K/s,the order of AF growth rate in-duced by different inclusions,as reported in literature,is Ti-O<Ti-Ca-Zr-Al-O<Mg-O<Ti-Zr-Al-O<Mn-Ti-Al-O<Ti-Al-O<Zr-Ti-Al-O.Further comprehensive experiments are required to investigate the quantitative relationship between the formation of AFs and inclusions.展开更多
当前,大规模室外基础设施的数字化需求持续扩大,基于深度学习的自动扫描到建筑信息模型(scanning to building information modeling, Scan2BIM)通过卓越的特征学习能力和自动化流程显著提升了建模精度和构建速度,在结构复杂的室外场景...当前,大规模室外基础设施的数字化需求持续扩大,基于深度学习的自动扫描到建筑信息模型(scanning to building information modeling, Scan2BIM)通过卓越的特征学习能力和自动化流程显著提升了建模精度和构建速度,在结构复杂的室外场景重建中发挥了关键作用.文中介绍了Scan2BIM的4大核心模块及其相关研究进展.其中,针对3D点云获取模块,从采集设备与采集来源2个维度概括了3D点云数据采集的技术发展,并着重梳理了代表性3D点云数据集;根据学习方式的不同,将大规模点云对齐算法划分为基于优化和深度学习2大类,并从精准度、计算效率、鲁棒性等多维度对比分析了相关工作;在点云分割模块中,分别对点云全景分割和点云实例分割算法通过统一的评估指标进行了整理归纳;对于BIM自动化建模,简述了BIM核心互操作标准体系,并分类总结了多种几何实体建模与关系建模算法.最后,通过深入分析和前瞻性探讨,指出了现阶段大规模室外场景建模的高效性、精准性、泛化性与统一性的无法有效结合的问题;未来将重点围绕多源数据融合建模、精度与鲁棒性协同优化、端到端Scan2BIM通用框架构建以及大模型应用与探索等方向展开.展开更多
The high-temperature dissolution behavior of primary carbides in samples taken from GCr15 continuous-casting bloom was observed in-situ by confocal laser scanning microscopy.Equations were fitted to the dissolution ki...The high-temperature dissolution behavior of primary carbides in samples taken from GCr15 continuous-casting bloom was observed in-situ by confocal laser scanning microscopy.Equations were fitted to the dissolution kinetics of primary carbides during either heating or soaking.Dissolution of carbides proceeded in three stages(fast→slow→faster)as either temperature or holding time was increased.During the heating process and during the first and third stages of the soaking process,the original size of the carbides determined the steepness of the slope,but during the middle(“slow”)stage of the soaking process,the slope remained zero.The initial size of the carbides varied greatly,but their final dissolution temperature fell within the narrow range of 1210-1235℃,and the holding time remained within 50 min.Fractal analysis was used to study the morphological characteristics of small and medium-sized carbides during the dissolution process.According to changes in the fractal dimension before and after soaking,the carbides tended to evolve towards a more regular morphology.展开更多
The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods fo...The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.展开更多
To investigate the nucleation behavior during the single-phased metallic solidification process,the commercial ultrapure ferritic stainless steels with no(Initial steel)and various melt treatments(R1,MR1,Y2,MY1,and M1...To investigate the nucleation behavior during the single-phased metallic solidification process,the commercial ultrapure ferritic stainless steels with no(Initial steel)and various melt treatments(R1,MR1,Y2,MY1,and M1 steels)were used to carry out the differential scanning colorimetry(DSC)and high-temperature confocal laser scanning microscope(HT-CLSM)experiments.Based on the results of DSC experiments,the equilibrium solidification process as well as the relationship among the critical undercooling degree(△T_(c)^(DSC)),latent heat of fusion/crystallization(△H_(f)/△H_(c)),equiaxed grain ratio(ER),and average grain size(△_(ave)^(ingot))was revealed.ER is increased with the decreasing△T_(c)^(DSC)and increasing△H_(f)/△H_(c);however,△_(ave)^(ingot)is decreased with them.Referring to the results of HT-CLSM experiments,the average sizes of micro-/macrostructures(d_(ave)/D_(ave)/)are decreased with the increasing cooling rate,as well as the difference between and apparent critical undercooling degree(△T_(c)^(CLSM))was revealed.The heterogeneous nucleation of the crystal nuclei occurs only if△T_(c)^(CLSM)>△T_(c)^(DSC).Combining with the interfacial wetting-lattice mismatch heterogeneous nucleation model,the dynamic mechanism of the metallic solidification was revealed.The as-cast grains of the melt-treated samples were obviously refined,owing to the much higher actual heterogeneous nucleation rates(I_(heter.,i))obtained through melt treatments,and the heterogeneous nucleation rates(I_(heter.,ij))for all samples are increased with the cooling rates,firmly confirming that the as-cast grains of each sample could be refined by the increasing cooling rates.展开更多
文摘The spatial resolution of a commercial two-dimensional(2D)ionization chamber(IC)array is limited by the size of the individual detector and the center-to-center distance between sensors.For dose distributions with areas of steep dose gradients,inter-detector dose values are derived by the interpolation of nearby detector readings in the conventional mathematical interpolation of 2D IC array measurements.This may introduce significant errors,particularly in proton spot scanning radiotherapy.In this study,by combining logfile-based reconstructed dose values and detector measurements with the Laplacian pyramid image blending method,a novel method is proposed to obtain a reformatted dose distribution that provides an improved estimation of the delivered dose distribution with high spatial resolution.Meanwhile,the similarity between the measured original data and the downsampled logfilebased reconstructed dose is regarded as the confidence of the reformatted dose distribution.Furthermore,we quantify the performance benefits of this new approach by directly comparing the reformatted dose distributions with 2D IC array detector mathematically interpolated measurements and original low-resolution measurements.The result shows that this new method is better than the mathematical interpolation and achieves gamma pass rates similar to those of the original low-resolution measurements.The reformatted dose distributions generally yield a confidence exceeding 95%.
基金supported by the National Key R&D Program of China(No.2023YFB3709900)the National Nature Science Foundation of China(No.U22A20171)+1 种基金the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202315)the High Steel Center(HSC)at North China University of Technology and University of Science and Technology Beijing,China.
文摘Desulfurization of CaO–Al_(2)O_(3) particles in molten steel was observed in situ using high-temperature confocal scanning laser microscopy.The effects of the aluminum and silicon contents of molten steel on desulfurization were analyzed.When the total aluminum content in the steel increased from 6 to 1100 ppm,the CaS content in CaO–Al_(2)O_(3) particles increased from 2.1wt%to 84.84wt%after the reaction for 90 s.Furthermore,when the silicon content in the steel increased from 0.01wt%to 2.20wt%,the CaS content in CaO–Al_(2)O_(3) particles increased from 1.53wt%to 79.01wt%after the reaction for 90 s.This indicates that the increase in the aluminum and silicon contents of the steel promoted the desulfurization of CaO–Al_(2)O_(3) particles.A kinetic model was established to predict the CaO–Al_(2)O_(3) particles composition,and the diffusion coefficient of sulfur in CaO–Al_(2)O_(3) particles was 9.375×10^(−10)m^(2)·s^(−1) at 1600℃,which provided a new method for the calculation of diffusion coefficient.
文摘Objective:To explore the application effect of digital intraoral scanning impression technique in oral implant restoration for periodontitis patients and analyze its impact on patients’Visual Analogue Scale(VAS)scores.Methods:A total of 80 periodontitis patients who received implant restoration in our hospital from May 2023 to May 2025 were selected as research subjects.They were randomly divided into an observation group and a control group using a random number table method,with 40 cases in each group.The observation group used the digital intraoral scanning impression technique to obtain impressions,while the control group used the traditional silicone rubber impression technique.The impression-taking time,the number of prostheses try-ins,implant survival rate,periodontal health indicators(probing depth,gingival index,bleeding index),and VAS scores(pain during treatment and comfort after restoration)were compared between the two groups.Results:The observation group was superior to the control group in terms of impression-taking time,the number of prostheses try-ins,and implant survival rate(p<0.05).Six months after restoration,the improvement in periodontal health indicators in the observation group was significantly better than that in the control group(p<0.05).In addition,the pain VAS score of the observation group during treatment was lower than that of the control group,and the comfort VAS score after restoration was higher than that of the control group(p<0.05).Conclusion:Digital intraoral scanning impression technology can effectively enhance the efficiency and success rate of implant restoration in periodontitis patients,improve periodontal health,alleviate patients’discomfort during treatment,and increase post-restoration comfort,demonstrating high clinical application value.
文摘In this review, a group ot two-dimensional （2D） hydrogen-bonded supramolecular networks developed in our laboratory are discussed. Our attention is mainly focused on： （1） recognition of Fe3＋ through twocomponent molecular networks; （2） site-selective fabrication of 2D fullerene arrays; and （3） fabrication of the nanoporous structure regulated by photoisomerization reaction process. It is envisioned that special supramolecular nanostructures, through H-bonding interactions, can be constructed or reconstructed to be further investigated toward the research of multi-component systems, molecule recognition, single molecular switches, and host-vip supramolecular chemistry.
文摘Some theorems of compactly supported non-tensor product form two-dimension Daubechies wavelet were analysed carefully. Compactly supported non-tensor product form two-dimension wavelet was constructed, then non-tensor product form two dimension wavelet finite element was used to solve the deflection problem of elastic thin plate. The error order was researched. A numerical example was given at last.
基金Sponsored by the National Natural Science Foundation of China(10676120)Laboratory of Computational Physics Foundation(9140C690101070C69)
文摘The adaptive mesh refinement （AMR） method is applied in the 2-D Euler multi-component elasticplastic hydrodynamics code （MEPH2Y）. It is applied on detonation. Firstly, the AMR method is described, including a conservative spatial interpolation, the time integration methodology with the adapitve time increment and an adaptive computational region method. The advantage of AMR technique is exhibited by numerical examples, including the 1-D C-J detonation and the 2-D implosion ignited from a single point. Results show that AMR can promote the computational efficiency, keeping the accuracy in interesting regions.
基金by the National Natural Science Foundation of China(Nos.21334003 and 21674052).
文摘The polyacidic character of polyoxometalate(POM)clusters endows high ionic conductivity,making these clusters good candidates for solar and fuel cells.Covalent bonding of clusters to polymer chains creates poly(POM)s that are polyelectrolytes with both cluster functions and polymer performance.Thus,solution-processable poly(POM)s are expected to be used as key materials in advanced devices.Further understanding of poly(POM)s will optimize the preparation process and improve device performance.Herein,we report a study of the first linear poly(POM)s by directly visualizing the chains using scanning transmission electron microscopy.Compared with traditional polymers,individual clusters of poly(POM)s can be directly visualized because of the resistance to electron-beam damage and the high contrast of the tungsten POM pendants.Thus,cluster aggregates with diverse shapes were observed.Counting the number of clusters in the aggregates allowed the degree of polymerization and molecular weight distribution to be determined,and studying the aggregate shapes revealed the presence of a curved semirigid chain in solution.Further study of shape diversity revealed that strong interactions between clusters determine the diverse chain shapes formed during solution processing.Fundamental insight is critical to understanding the formation of poly(POM)films from solutions as key functional materials,especially for fuel and solar cells.
基金Project supported by the National Key Research&Development Program of China(Grant Nos.2016YFA0202300 and 2018YFA0305800)the National Natural Science Foundation of China(Grant Nos.61504149,61725107,51572290,and 61622116)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB30000000 and XDB28000000)the University of Chinese Academy of Sciencesthe CAS Key Laboratory of Vacuum Physics
文摘Two-dimensional(2 D) materials provide a platform to exploit the novel physical properties of functional nanodevices.Here, we report on the formation of a new 2 D layered material, a well-ordered monolayer TiTe_2, on a Au(111) surface by molecular beam epitaxy(MBE). Low-energy electron diffraction(LEED) measurements of the samples indicate that the TiTe_2 film forms(√3 ×√7) superlattice with respect to the Au(111) substrate, which has three different orientations. Scanning tunneling microscopy(STM) measurements clearly show three ordered domains consistent with the LEED patterns.Density functional theory(DFT) calculations further confirm the formation of 2 H-TiTe_2 monolayer on the Au(111) surface with Te as buffer layer. The fabrication of this 2 D layered heterostructure expands 2 D material database, which may bring new physical properties for future applications.
文摘By considering the effect of suspended solid particles in the ordinary equations for two-dimension inviscid incompressible mixing layer, the Rayleigh equation and the modified Rayleigh equation are obtained. And then, by solving the corresponding eigen-value equations with numerical computational method, the relation curves between perturbation frequency and spacial growth rate of the mixing layer for the varying particle loading, ratio of particle velocity to fluid velocity and Stokes number are got. Sever al important conclusions on the effect of suspended solid particles on unstability of the mixing layer are presented in the end by analyzing all the relation curves.
基金Funded by the Shanxi Province Science Foundation for Youths(2006021026)
文摘The surface quality of fine-grained ZrO2 engineering ceramic were researched using 270# diamond wheel both with and without work-piece two-dimension ultrasonic vibration grinding（WTDUVG）. By AFM images, the surface topography and the micro structure of the two-dimensional ultrasonic vibration grinding ceramics were especially analyzed. The experimental results indicate that the surface roughness is related to grinding vibration mode and the material removal mechanism. Surface quality of WTDUVG is superior to that of conventional grinding, and it is easy for two-dimensional ultrasonic vibration grinding that material removal mechanism is ductile mode grinding.
基金Project supported by the National Key Basic Research Program of China(Grant No.2017YFA0205004)the National Natural Science Foundation of China(Grant Nos.92165201,11474261,and 11634011)+1 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.WK3510000006,and WK3430000003)the Anhui Initiative in Quantum Information Technologies(Grant No.AHY170000)。
文摘Nanoclusters consisting of a few atoms have attracted a lot of research interests due to their exotic size-dependent properties. Here, well-ordered two-dimensional Sb cluster superlattice was fabricated on Si substrate by a two-step method and characterized by scanning tunneling microscopy. High resolution scanning tunneling microscope measurements revealed the fine structures of the Sb clusters, which consist of several Sb atoms ranging from 2 to 7. Furthermore, the electronic structure of the nanocluster displays the quantized energy-level which is due to the single-electron tunneling effects. We believe that the fabrication of Sb cluster superlattice broadens the species of the cluster superlattice and provides a promising candidate to further explore the novel physical and chemical properties of the semimetal nanocluster.
文摘Pure mesoporous ZrO2 thin film with two-dimensional hexagonal framework mesostructure has been successfully prepared by using a nonionic triblock copolymer as the structure-directing agent and ZrCl4 as the zireonia source through evaporation-induced self-assembly approach. The resulting materials were characterized by X-ray diffraction, scanning electron microscope, and nitrogen adsorption ,neasurenlents. The obtained mesoporous ZrO2 thin film has a nanocrystalline inorganic framework （tetragonal zirconia） and narrowly distributed mcsopore size （6. 7 nm in diameter].
基金This research was financially supported by the National Natural Science Foundation of China （Grant NO. 00000000） and the Fundamental Research Funds for Central University （Grant NO.TD2010-2）.
文摘As a kind of subculture, The two-dimensional culture came of age during the 1970s in Japan and spread to China in the 1980s. In China, the culture has become an important economic force and social capital get more and more attention to it as well. This paper mainly discusses the origin and development of the two-dimensional clothing, and summed up the inherent characteristics and the internal developing law of it, furthermore, on the stage of current situation of two-dimensional economy this paper will conclude the development trend of next days.
基金supported by the National Key R&D Program(No.2023YFB3709900)the National Nature Science Foundation of China(No.U22A20171)+2 种基金China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202315)the High Steel Center(HSC)at North China University of TechnologyUniversity of Science and Technology Beijing,China.
文摘The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are reviewed and summarized,particularly the col-lision of various inclusions,dissolution of inclusions in liquid slag,and reactions between inclusions and steel.Solid inclusions exhibited a high collision tendency,whereas pure liquid inclusions exhibited minimal collisions because of the small attraction force induced by their<90°contact angle with molten steel.The collision of complex inclusions in molten steel was not included in the scope of this study and should be evaluated in future studies.Higher CaO/Al_(2)O_(3)and CaO/SiO_(2)ratios in liquid slag promoted the dissolution of Al_(2)O_(3)-based in-clusions.The formation of solid phases in the slag should be prevented to improve dissolution of inclusions.To accurately simulate the dissolution of inclusions in liquid slag,in-situ observation of the dissolution of inclusions at the steel-slag interface is necessary.Using a combination of CSLM and scanning electron microscopy-energy dispersive spectroscopy,the composition and morphological evolution of the inclusions during their modification by the dissolved elements in steel were observed and analyzed.Although the in-situ observa-tion of MnS and TiN precipitations has been widely studied,the in-situ observation of the evolution of oxide inclusions in steel during so-lidification and heating processes has rarely been reported.The effects of temperature,heating and cooling rates,and inclusion character-istics on the formation of acicular ferrites(AFs)have been widely studied.At a cooling rate of 3-5 K/s,the order of AF growth rate in-duced by different inclusions,as reported in literature,is Ti-O<Ti-Ca-Zr-Al-O<Mg-O<Ti-Zr-Al-O<Mn-Ti-Al-O<Ti-Al-O<Zr-Ti-Al-O.Further comprehensive experiments are required to investigate the quantitative relationship between the formation of AFs and inclusions.
文摘当前,大规模室外基础设施的数字化需求持续扩大,基于深度学习的自动扫描到建筑信息模型(scanning to building information modeling, Scan2BIM)通过卓越的特征学习能力和自动化流程显著提升了建模精度和构建速度,在结构复杂的室外场景重建中发挥了关键作用.文中介绍了Scan2BIM的4大核心模块及其相关研究进展.其中,针对3D点云获取模块,从采集设备与采集来源2个维度概括了3D点云数据采集的技术发展,并着重梳理了代表性3D点云数据集;根据学习方式的不同,将大规模点云对齐算法划分为基于优化和深度学习2大类,并从精准度、计算效率、鲁棒性等多维度对比分析了相关工作;在点云分割模块中,分别对点云全景分割和点云实例分割算法通过统一的评估指标进行了整理归纳;对于BIM自动化建模,简述了BIM核心互操作标准体系,并分类总结了多种几何实体建模与关系建模算法.最后,通过深入分析和前瞻性探讨,指出了现阶段大规模室外场景建模的高效性、精准性、泛化性与统一性的无法有效结合的问题;未来将重点围绕多源数据融合建模、精度与鲁棒性协同优化、端到端Scan2BIM通用框架构建以及大模型应用与探索等方向展开.
基金supported by Independent Research Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(SKLASS-2023-Z13)the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200)+1 种基金A portion of the work was performed at US National High Magnetic Field Laboratory,which is supported by the National Science Foundation(Cooperative Agreement No.DMR-1157490 and DMR-1644779)the State of Florida.Thanks also to Mary Tyler for editing.
文摘The high-temperature dissolution behavior of primary carbides in samples taken from GCr15 continuous-casting bloom was observed in-situ by confocal laser scanning microscopy.Equations were fitted to the dissolution kinetics of primary carbides during either heating or soaking.Dissolution of carbides proceeded in three stages(fast→slow→faster)as either temperature or holding time was increased.During the heating process and during the first and third stages of the soaking process,the original size of the carbides determined the steepness of the slope,but during the middle(“slow”)stage of the soaking process,the slope remained zero.The initial size of the carbides varied greatly,but their final dissolution temperature fell within the narrow range of 1210-1235℃,and the holding time remained within 50 min.Fractal analysis was used to study the morphological characteristics of small and medium-sized carbides during the dissolution process.According to changes in the fractal dimension before and after soaking,the carbides tended to evolve towards a more regular morphology.
基金supported by National Natural Science Foundation of China(No.52176122).
文摘The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.52274339,52174321,52074186,and 52104337)Natural Science Foundation of Jiangsu Province(Grant No.BK20231317)China Baowu Low-Carbon Metallurgy Innovation Fund(Grant No.BWLCF202108).
文摘To investigate the nucleation behavior during the single-phased metallic solidification process,the commercial ultrapure ferritic stainless steels with no(Initial steel)and various melt treatments(R1,MR1,Y2,MY1,and M1 steels)were used to carry out the differential scanning colorimetry(DSC)and high-temperature confocal laser scanning microscope(HT-CLSM)experiments.Based on the results of DSC experiments,the equilibrium solidification process as well as the relationship among the critical undercooling degree(△T_(c)^(DSC)),latent heat of fusion/crystallization(△H_(f)/△H_(c)),equiaxed grain ratio(ER),and average grain size(△_(ave)^(ingot))was revealed.ER is increased with the decreasing△T_(c)^(DSC)and increasing△H_(f)/△H_(c);however,△_(ave)^(ingot)is decreased with them.Referring to the results of HT-CLSM experiments,the average sizes of micro-/macrostructures(d_(ave)/D_(ave)/)are decreased with the increasing cooling rate,as well as the difference between and apparent critical undercooling degree(△T_(c)^(CLSM))was revealed.The heterogeneous nucleation of the crystal nuclei occurs only if△T_(c)^(CLSM)>△T_(c)^(DSC).Combining with the interfacial wetting-lattice mismatch heterogeneous nucleation model,the dynamic mechanism of the metallic solidification was revealed.The as-cast grains of the melt-treated samples were obviously refined,owing to the much higher actual heterogeneous nucleation rates(I_(heter.,i))obtained through melt treatments,and the heterogeneous nucleation rates(I_(heter.,ij))for all samples are increased with the cooling rates,firmly confirming that the as-cast grains of each sample could be refined by the increasing cooling rates.
