Grinding,a critical precision machining process for difficult-to-cut alloys,has undergone continual technological advancements to improve machining efficiency.However,the sustainability of this process is gaining heig...Grinding,a critical precision machining process for difficult-to-cut alloys,has undergone continual technological advancements to improve machining efficiency.However,the sustainability of this process is gaining heightened attention due to significant challenges associated with the substantial specific grinding energy and the extensive heat generated when working with difficult-to-cut alloys,renowned for their exceptional physical and mechanical properties.In response to these challenges,the widespread application of massive coolant in manufacturing industries to dissipate grinding heat has led to complex post-cleaning and disposal processes.This,in turn,has resulted in issues such as large energy consumption,a considerable carbon footprint,and concerns related to worker health and safety,which have become the main factors that restrict the development of grinding technology.This paper provides a holistic review of sustainability in grinding difficult-to-cut alloys,encompassing current trends and future directions.The examination extends to developing grinding technologies explicitly tailored for these alloys,comprehensively evaluating their sustainability performance.Additionally,the exploration delves into innovative sustainable technologies,such as heat pipe/oscillating heat pipe grinding wheels,minimum quantity lubrication,cryogenic cooling,and others.These groundbreaking technologies aim to reduce dependence on hazardous coolants,minimizing energy and resource consumption and carbon emissions associated with coolant-related or subsequent disposal processes.The essence of these technologies lies in their potential to revolutionize traditional grinding practices,presenting environmentally friendly alternatives.Finally,future development trends and research directions are put forward to pursue the current limitation of sustainable grinding for difficult-to-cut alloys.This paper can guide future research and development efforts toward more environmentally friendly grinding operations by understanding the current state of sustainable grinding and identifying emerging trends.展开更多
Although the selective hydrogenation ofα,β-unsaturated aldehyde to unsaturated alcohol(UOL)is an extremely important transformation,it is still a great challenge to achieve high selectivity to UOL due to thermodynam...Although the selective hydrogenation ofα,β-unsaturated aldehyde to unsaturated alcohol(UOL)is an extremely important transformation,it is still a great challenge to achieve high selectivity to UOL due to thermodynamic favoring of the C=C hydrogenation over the C=O hydrogenation.Herein,we report that iridium nanoclusters(Ir NCs)confined within hollow MIL-101(Fe)expresses satisfied reaction activity(93.9%)and high selectivity(96.2%)for the hydrogenation of cinnamaldehyde(CAL)to cinnamyl alcohol(COL)under 1 bar H;atmosphere and room temperature.The unique hollow structure of MIL-101(Fe)benefits for the fast transport of reactant,ensuring the comparable reaction activity and better recyclability of Ir@MIL-101(Fe)than the counterparts which Ir NCs were on the surface of MIL-101(Fe).Furthermore,The X-ray photoelectron spectroscopy data indicates the electropositive Ir NCs,owing to the electron transfer from Ir to MIL-101(Fe),can interact with oxygen lone pairs,and Fourier transform infrared spectrum shows the Lewis acid sites in MIL-101(Fe)can strongly interact with C=O bond,which contributes to a high selectivity for COL.This work suggests the considerable potential of synergetic effect between hollow MOFs and metal nanoclusters for selective hydrogenation reactions.展开更多
With the advent of the fourth industrial revolution,the new generation of information technology industry represented by the internet of things(IoT)has continually nurtured new business models and economic growth poin...With the advent of the fourth industrial revolution,the new generation of information technology industry represented by the internet of things(IoT)has continually nurtured new business models and economic growth points and created one after another IoT mythology,which greatly promoted the global socioeconomic development and transformation.IoT has increasingly become the new engine of the current global economic development.To this end,this paper starts with the concept and connotation of the IoT,discusses the development and application of the global IoT and the types and characteristics of the IoT business model,and proposes the measures and countermeasures of the business model of the IoT in the context of globalization.展开更多
GH4169D superalloy exhibits exceptional service performance,enhancing the capabilities of aero-engines.However,it also poses challenges to component machining.Ultrasonic vibration-assisted machining has demonstrated a...GH4169D superalloy exhibits exceptional service performance,enhancing the capabilities of aero-engines.However,it also poses challenges to component machining.Ultrasonic vibration-assisted machining has demonstrated advantages in enhancing material machinability.However,comprehensive analyses that pertain to the tool cutting edge path,material removal mechanism,and surface texture in longitudinal ultrasonic vibration-assisted side-milling(LUVM)are rare.In this study,GH4169D superalloy was subjected to LUVM and conventional milling(CM)to investigate the material removal mechanism and surface texture generation.Furthermore,a noncutting time ratio model was proposed to predict the reduction in maximum milling force achieved by LUVM.Results indicated that compared with that of CM,the machining of LUVM was divided into milling and noncutting.The inclusion of noncutting contributed to a reduction in the maximum milling force during LUVM.However,as milling speed increased,noncutting time ratio decreased and subsequently diminished the advantage of LUVM.The chip morphology formed using LUVM exhibited a greater degree of curliness compared with that obtained using CM,facilitating chip breaking.The utilization of LUVM resulted in the formation of a thinner lamellar structure on the free surface of chips compared with the use of CM.The machined surface exhibited a distinct ultrasonic vibration texture in LUVM,which was characterized by a physics formula.The utilization of LUVM demonstrated a reduction in machined surface roughness Ra compared with the use of CM at a low milling speed.The findings of this study contribute to the prediction of the effects of LUVM on reducing maximum milling force and achieving control over chip morphologies and machined surface texture.展开更多
Robust genome editing technologies are becoming part of the crop breeding toolbox.Currently,genome editing is usually conducted either at a single locus,or multiple loci,in a variety at one time.Massively parallel gen...Robust genome editing technologies are becoming part of the crop breeding toolbox.Currently,genome editing is usually conducted either at a single locus,or multiple loci,in a variety at one time.Massively parallel genomics platforms,multifaceted genome editing capabilities,and flexible transformation systems enable targeted variation at nearly any locus,across the spectrum of genotypes within a species.We demonstrate here the simultaneous transformation and editing of many genotypes,by targeting mixed seed embryo explants with genome editing machinery,followed by re-identification through genotyping after plant regeneration.Transformation and Editing of Mixed Lines(TREDMIL)produced transformed individuals representing 101 of 104(97%)mixed elite genotypes in soybean;and 22 of 40(55%)and 9 of 36(25%)mixed maize female and male elite inbred genotypes,respectively.Characterization of edited genotypes for the regenerated individuals identified over 800 distinct edits at the Determinate1(Dt1)locus in samples from 101 soybean genotypes and 95 distinct Brown midrib3(Bm3)edits in samples from 17 maize genotypes.These results illustrate how TREDMIL can help accelerate the development and deployment of customized crop varieties for future precision breeding.展开更多
Nucleate pool boiling process is widely used in heat exchangers because of its excellent heat transfer performance.With the gradual increase of applications,more and more equipments work in a non-static state,but ther...Nucleate pool boiling process is widely used in heat exchangers because of its excellent heat transfer performance.With the gradual increase of applications,more and more equipments work in a non-static state,but there is little research under rolling conditions.Therefore,it is necessary to investigate the influence of rolling motion on the nucleate pool boiling process.In this study,a numerical investigation of the nucleate pool boiling process under static and rolling conditions is performed based on the volume-of-fluid(VOF)method.Physical fields and phase distribution under static state and rolling motion are compared to investigate the effect of rolling motion on the nucleate pool boiling process.The results show that rolling motion greatly influences the bubble behavior and void fraction owing to the differences between flow fields.The void fraction decreased by 11.84%,48.82%,and 56.87%as the maximum rolling angle increased from 15°to 45°,and by 11.84%,22.27%,and 21.81%as the rolling period increased from 1 s to 3 s.The void fraction decreased by 11.84%,48.82%,and 56.87%as the maximum rolling angle increased from 15°to 45°.The heat transfer coefficients of different cases are compared,and it is found that the effects of rolling motion on heat transfer coefficients can be ignored.展开更多
基金Supported by National Natural Science Foundation of China(Nos.52205476,92160301)Youth Talent Support Project of Jiangsu Provincial Association of Science and Technology of China(Grant No.TJ-2023-070)+2 种基金Science Center for Gas Turbine Project(Grant No.P2023-B-IV-003-001)Fund of Prospective Layout of Scientific Research for the Nanjing University of Aeronautics and Astronautics of China(Grant No.1005-ILB23025-1A)Fund of Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology of China(Grant No.1005-ZAA20003-14).
文摘Grinding,a critical precision machining process for difficult-to-cut alloys,has undergone continual technological advancements to improve machining efficiency.However,the sustainability of this process is gaining heightened attention due to significant challenges associated with the substantial specific grinding energy and the extensive heat generated when working with difficult-to-cut alloys,renowned for their exceptional physical and mechanical properties.In response to these challenges,the widespread application of massive coolant in manufacturing industries to dissipate grinding heat has led to complex post-cleaning and disposal processes.This,in turn,has resulted in issues such as large energy consumption,a considerable carbon footprint,and concerns related to worker health and safety,which have become the main factors that restrict the development of grinding technology.This paper provides a holistic review of sustainability in grinding difficult-to-cut alloys,encompassing current trends and future directions.The examination extends to developing grinding technologies explicitly tailored for these alloys,comprehensively evaluating their sustainability performance.Additionally,the exploration delves into innovative sustainable technologies,such as heat pipe/oscillating heat pipe grinding wheels,minimum quantity lubrication,cryogenic cooling,and others.These groundbreaking technologies aim to reduce dependence on hazardous coolants,minimizing energy and resource consumption and carbon emissions associated with coolant-related or subsequent disposal processes.The essence of these technologies lies in their potential to revolutionize traditional grinding practices,presenting environmentally friendly alternatives.Finally,future development trends and research directions are put forward to pursue the current limitation of sustainable grinding for difficult-to-cut alloys.This paper can guide future research and development efforts toward more environmentally friendly grinding operations by understanding the current state of sustainable grinding and identifying emerging trends.
基金supported by National Key R&D Program of China(No.2018YFA0108300)the Overseas High-level Talents Plan of China and Guangdong Province+3 种基金the 100 Talents Plan Foundation of Sun Yat-sen Universitythe Fundamental Research Funds for the Central Universitiesthe Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2017ZT07C069)the NSFC Projects(Nos.21905315 and 22075321)。
文摘Although the selective hydrogenation ofα,β-unsaturated aldehyde to unsaturated alcohol(UOL)is an extremely important transformation,it is still a great challenge to achieve high selectivity to UOL due to thermodynamic favoring of the C=C hydrogenation over the C=O hydrogenation.Herein,we report that iridium nanoclusters(Ir NCs)confined within hollow MIL-101(Fe)expresses satisfied reaction activity(93.9%)and high selectivity(96.2%)for the hydrogenation of cinnamaldehyde(CAL)to cinnamyl alcohol(COL)under 1 bar H;atmosphere and room temperature.The unique hollow structure of MIL-101(Fe)benefits for the fast transport of reactant,ensuring the comparable reaction activity and better recyclability of Ir@MIL-101(Fe)than the counterparts which Ir NCs were on the surface of MIL-101(Fe).Furthermore,The X-ray photoelectron spectroscopy data indicates the electropositive Ir NCs,owing to the electron transfer from Ir to MIL-101(Fe),can interact with oxygen lone pairs,and Fourier transform infrared spectrum shows the Lewis acid sites in MIL-101(Fe)can strongly interact with C=O bond,which contributes to a high selectivity for COL.This work suggests the considerable potential of synergetic effect between hollow MOFs and metal nanoclusters for selective hydrogenation reactions.
文摘With the advent of the fourth industrial revolution,the new generation of information technology industry represented by the internet of things(IoT)has continually nurtured new business models and economic growth points and created one after another IoT mythology,which greatly promoted the global socioeconomic development and transformation.IoT has increasingly become the new engine of the current global economic development.To this end,this paper starts with the concept and connotation of the IoT,discusses the development and application of the global IoT and the types and characteristics of the IoT business model,and proposes the measures and countermeasures of the business model of the IoT in the context of globalization.
基金supported by the National Natural Science Foundation of China(Grant Nos.92160301,92060203,52175415,and 52205475)the Science Center for Gas Turbine Project(Grant No.P2023-B-IV-003-001)+3 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20210295)the Key Research and Development Program of Jiangsu Province,China(Grant No.BE2022106)the Huaqiao University Engineering Research Center of Brittle Materials Machining,China(Grant No.2023IME-001)the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX22_0342).
文摘GH4169D superalloy exhibits exceptional service performance,enhancing the capabilities of aero-engines.However,it also poses challenges to component machining.Ultrasonic vibration-assisted machining has demonstrated advantages in enhancing material machinability.However,comprehensive analyses that pertain to the tool cutting edge path,material removal mechanism,and surface texture in longitudinal ultrasonic vibration-assisted side-milling(LUVM)are rare.In this study,GH4169D superalloy was subjected to LUVM and conventional milling(CM)to investigate the material removal mechanism and surface texture generation.Furthermore,a noncutting time ratio model was proposed to predict the reduction in maximum milling force achieved by LUVM.Results indicated that compared with that of CM,the machining of LUVM was divided into milling and noncutting.The inclusion of noncutting contributed to a reduction in the maximum milling force during LUVM.However,as milling speed increased,noncutting time ratio decreased and subsequently diminished the advantage of LUVM.The chip morphology formed using LUVM exhibited a greater degree of curliness compared with that obtained using CM,facilitating chip breaking.The utilization of LUVM resulted in the formation of a thinner lamellar structure on the free surface of chips compared with the use of CM.The machined surface exhibited a distinct ultrasonic vibration texture in LUVM,which was characterized by a physics formula.The utilization of LUVM demonstrated a reduction in machined surface roughness Ra compared with the use of CM at a low milling speed.The findings of this study contribute to the prediction of the effects of LUVM on reducing maximum milling force and achieving control over chip morphologies and machined surface texture.
文摘Robust genome editing technologies are becoming part of the crop breeding toolbox.Currently,genome editing is usually conducted either at a single locus,or multiple loci,in a variety at one time.Massively parallel genomics platforms,multifaceted genome editing capabilities,and flexible transformation systems enable targeted variation at nearly any locus,across the spectrum of genotypes within a species.We demonstrate here the simultaneous transformation and editing of many genotypes,by targeting mixed seed embryo explants with genome editing machinery,followed by re-identification through genotyping after plant regeneration.Transformation and Editing of Mixed Lines(TREDMIL)produced transformed individuals representing 101 of 104(97%)mixed elite genotypes in soybean;and 22 of 40(55%)and 9 of 36(25%)mixed maize female and male elite inbred genotypes,respectively.Characterization of edited genotypes for the regenerated individuals identified over 800 distinct edits at the Determinate1(Dt1)locus in samples from 101 soybean genotypes and 95 distinct Brown midrib3(Bm3)edits in samples from 17 maize genotypes.These results illustrate how TREDMIL can help accelerate the development and deployment of customized crop varieties for future precision breeding.
文摘Nucleate pool boiling process is widely used in heat exchangers because of its excellent heat transfer performance.With the gradual increase of applications,more and more equipments work in a non-static state,but there is little research under rolling conditions.Therefore,it is necessary to investigate the influence of rolling motion on the nucleate pool boiling process.In this study,a numerical investigation of the nucleate pool boiling process under static and rolling conditions is performed based on the volume-of-fluid(VOF)method.Physical fields and phase distribution under static state and rolling motion are compared to investigate the effect of rolling motion on the nucleate pool boiling process.The results show that rolling motion greatly influences the bubble behavior and void fraction owing to the differences between flow fields.The void fraction decreased by 11.84%,48.82%,and 56.87%as the maximum rolling angle increased from 15°to 45°,and by 11.84%,22.27%,and 21.81%as the rolling period increased from 1 s to 3 s.The void fraction decreased by 11.84%,48.82%,and 56.87%as the maximum rolling angle increased from 15°to 45°.The heat transfer coefficients of different cases are compared,and it is found that the effects of rolling motion on heat transfer coefficients can be ignored.
