The enhancement of interface bonding between cement and polymerand the structural reticula- tion of the water-soluble polymer areproposed to minimize the shortening of the mechanical properties ofmacro-de- fect-free(M...The enhancement of interface bonding between cement and polymerand the structural reticula- tion of the water-soluble polymer areproposed to minimize the shortening of the mechanical properties ofmacro-de- fect-free(MDF)cement based composites at high relativehumidity. The MDF composites incorporated with vari- ouscross-coupling agents studied experimentally. The results show thatthe MDF composites modified with small amounts of cross-couplingagent had raised mechanical properties, but it is more important thatthe modified MDF composites had a significant increase in waterresistance compared to the original one.展开更多
Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom c...Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom can be recovered back to its original position without any defects introduced. Based on surface hydroxylation and chemisorption theory, material removal mechanism of quartz glass in the elastic mode is analyzed to obtain defect-free surface. Elastic contact condition between nanoparticle and quartz glass surface is confirmed from the Hertz contact theory model. Atoms on the quartz glass surface are removed by chemical bond generated by impact reaction in the elastic mode, so no defects are generated without mechanical process. Experiment was conducted on a numerically controlled system for nanoparticle jet polishing, and one flat quartz glass was polished in the elastic mode. Results show that scratches on the sample surface are completely removed away with no mechanical defects introduced, and microroughness(Ra) is decreased from 1.23 nm to 0.47 nm. Functional group Ce — O — Si on ceria nanoparticles after polishing was detected directly and indirectly by FTIR, XRD and XPS spectra analysis from which the chemical impact reaction is validated.展开更多
This paper presents the findings of a study on the helpful approaches to write essentially defectfree code among senior students majored in software engineering.In the first phase of the lab study,we prepared 9 coding...This paper presents the findings of a study on the helpful approaches to write essentially defectfree code among senior students majored in software engineering.In the first phase of the lab study,we prepared 9 coding projects for students which will help them to find their own best practices or principles to write essentially defect-free code before unit test.These students were interviewed regarding the use of their own best practices,their principles,and problems arising from the coding projects.We present qualitative and quantitative findings as well as our plans for second study phase including an industry field study.展开更多
The defect-free neutral atom array has emerged as an ideal platform to investigate complex many-body physics of interacting quantum particles,offering the opportunities for quantum simulation and quantum-enhanced metr...The defect-free neutral atom array has emerged as an ideal platform to investigate complex many-body physics of interacting quantum particles,offering the opportunities for quantum simulation and quantum-enhanced metrology.To fast build a large-scale quantum system,we design a sorting-atom algorithm with maximum parallelisms.Compared with previous protocols,our method saves the rearrangement time by sorting row-by-row and is also universal to arbitrary periodic patterns with no need to change the hardware.We present the generation of a defect-free square and other periodic geometries and demonstrate the potential to scale up a defect-free array to 2500 atoms with only about 180 steps of rearrangement.展开更多
Introducing defects into graphene has been widely utilized to realize the negative magnetoresistanee(MR)effect in graphene.However,the reported graphene negative MR exhibits only^10%under 10 T at room temperature to d...Introducing defects into graphene has been widely utilized to realize the negative magnetoresistanee(MR)effect in graphene.However,the reported graphene negative MR exhibits only^10%under 10 T at room temperature to date,which extremely limits the resolution of future spintronics devices.Moreover,intentional defect introduction can also cause unintentional degradation in graphene's intrinsic properties.In this paper,we report a magnetic logic inverter based on a crossed structure of defect-free graphene,resulting in a substantial gain of 4.81 mV/T while exhibiting room temperature operation.This crossed structure of graphene shows large unsaturated room temperature negative MR with an enhancement of up to 1,000%at 9 T.A transition behavior between negative and positive MR is observed in this crossed structure and the transition temperature can be tuned by a ratio of the conductivity between in-plane and out-of-plane transport.Our results open an intriguing path for future two-dimensional spintronics device applications.展开更多
Radiation defects-induced plastic flow localization is the origin of loss of ductility in irradiated metals.Defect-free channels(DFCs)are a typical form of strain localization that lead to crack initiation and prematu...Radiation defects-induced plastic flow localization is the origin of loss of ductility in irradiated metals.Defect-free channels(DFCs)are a typical form of strain localization that lead to crack initiation and premature failure.A comprehensive understanding of the DFC dynamics is key to managing radiation boosted property degradation.Despite great research efforts,a clear mechanism of DFC remains unknown.Here,our in-situ tests on irradiated Ni pillars provide a real-time observation of the dynamics of DFCs,including DFC initiation,extension and thickening.The merging and spreading of dislocation loops serve as an alternative mechanism of dislocation sources that emit massive dislocations and initiate nano-thick DFCs inside the grain.Nano-thick DFCs were formed through chopping up or sweeping away of loops by mobile dislocations.Annihilation of opposite loops and interactions between loops and vacancies accelerate DFC extension.Activation of multiple dislocation sources and dislocation cross-slips are the mechanisms for DFC thickening.展开更多
文摘The enhancement of interface bonding between cement and polymerand the structural reticula- tion of the water-soluble polymer areproposed to minimize the shortening of the mechanical properties ofmacro-de- fect-free(MDF)cement based composites at high relativehumidity. The MDF composites incorporated with vari- ouscross-coupling agents studied experimentally. The results show thatthe MDF composites modified with small amounts of cross-couplingagent had raised mechanical properties, but it is more important thatthe modified MDF composites had a significant increase in waterresistance compared to the original one.
基金Projects(51305450,51275521)supported by the National Natural Science Foundation of China
文摘Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom can be recovered back to its original position without any defects introduced. Based on surface hydroxylation and chemisorption theory, material removal mechanism of quartz glass in the elastic mode is analyzed to obtain defect-free surface. Elastic contact condition between nanoparticle and quartz glass surface is confirmed from the Hertz contact theory model. Atoms on the quartz glass surface are removed by chemical bond generated by impact reaction in the elastic mode, so no defects are generated without mechanical process. Experiment was conducted on a numerically controlled system for nanoparticle jet polishing, and one flat quartz glass was polished in the elastic mode. Results show that scratches on the sample surface are completely removed away with no mechanical defects introduced, and microroughness(Ra) is decreased from 1.23 nm to 0.47 nm. Functional group Ce — O — Si on ceria nanoparticles after polishing was detected directly and indirectly by FTIR, XRD and XPS spectra analysis from which the chemical impact reaction is validated.
文摘This paper presents the findings of a study on the helpful approaches to write essentially defectfree code among senior students majored in software engineering.In the first phase of the lab study,we prepared 9 coding projects for students which will help them to find their own best practices or principles to write essentially defect-free code before unit test.These students were interviewed regarding the use of their own best practices,their principles,and problems arising from the coding projects.We present qualitative and quantitative findings as well as our plans for second study phase including an industry field study.
基金supported by the National Key R&D Program of China(No.2020YFA0309400)the National Natural Science Foundation of China(Nos.12222409,12174081,and 11974228)+1 种基金the Key Research and Development Program of Shanxi Province(No.202101150101025)the financial support from the Royal Society Newton International Fellowship Alumni(AL201024)。
文摘The defect-free neutral atom array has emerged as an ideal platform to investigate complex many-body physics of interacting quantum particles,offering the opportunities for quantum simulation and quantum-enhanced metrology.To fast build a large-scale quantum system,we design a sorting-atom algorithm with maximum parallelisms.Compared with previous protocols,our method saves the rearrangement time by sorting row-by-row and is also universal to arbitrary periodic patterns with no need to change the hardware.We present the generation of a defect-free square and other periodic geometries and demonstrate the potential to scale up a defect-free array to 2500 atoms with only about 180 steps of rearrangement.
基金This work was supported by the National Natural Science Foundation Committee of the China Academy of Engineering Physics(NSAF)(No.U1630108)the joint fund of the National Key Research and Development Program of China(No.2017YFA0402902)+1 种基金the National Natural Science Foundation of China(No.11434009)This research was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘Introducing defects into graphene has been widely utilized to realize the negative magnetoresistanee(MR)effect in graphene.However,the reported graphene negative MR exhibits only^10%under 10 T at room temperature to date,which extremely limits the resolution of future spintronics devices.Moreover,intentional defect introduction can also cause unintentional degradation in graphene's intrinsic properties.In this paper,we report a magnetic logic inverter based on a crossed structure of defect-free graphene,resulting in a substantial gain of 4.81 mV/T while exhibiting room temperature operation.This crossed structure of graphene shows large unsaturated room temperature negative MR with an enhancement of up to 1,000%at 9 T.A transition behavior between negative and positive MR is observed in this crossed structure and the transition temperature can be tuned by a ratio of the conductivity between in-plane and out-of-plane transport.Our results open an intriguing path for future two-dimensional spintronics device applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.51922082,51971170,51942104 and11675230)the National Key Research and Development Program of China(2017YFB0702301)the 111 Project of China(Grant Number BP2018008)。
文摘Radiation defects-induced plastic flow localization is the origin of loss of ductility in irradiated metals.Defect-free channels(DFCs)are a typical form of strain localization that lead to crack initiation and premature failure.A comprehensive understanding of the DFC dynamics is key to managing radiation boosted property degradation.Despite great research efforts,a clear mechanism of DFC remains unknown.Here,our in-situ tests on irradiated Ni pillars provide a real-time observation of the dynamics of DFCs,including DFC initiation,extension and thickening.The merging and spreading of dislocation loops serve as an alternative mechanism of dislocation sources that emit massive dislocations and initiate nano-thick DFCs inside the grain.Nano-thick DFCs were formed through chopping up or sweeping away of loops by mobile dislocations.Annihilation of opposite loops and interactions between loops and vacancies accelerate DFC extension.Activation of multiple dislocation sources and dislocation cross-slips are the mechanisms for DFC thickening.
