Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials.In this study,four linear low-density polyethylenes(LLD...Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials.In this study,four linear low-density polyethylenes(LLDPEs)with comparable molecular weights but different short-chain branch(SCB)contents(ranging of 5-66 per 1000 carbon atoms)were modified via dynamic melt mixing using 2 wt% benzoyl peroxide at 145℃ and 50 r/min for 30 min.The influence of SCB content on the processability and structure of the resulting products was systematically investigated.All modified products exhibited good melt processability with melt flow rates(MFR)ranging from 0.46 g/10min to 1.07 g/10min.Products derived from low-SCB LLDPEs showed a lower MFR,higher cross-linking content,a larger number of long-chain branches,and a higher degree of benzoyl grafting.In contrast,those produced from high-SCB LLDPEs exhibited improved processability,reduced cross-linking,fewer long-chain branches,and lower benzoyl grafting levels.A detailed structural investigation of the soluble and insoluble fractions,which were separated using trichlorobenzene fractionation,was conducted to analyze the structural features of various modified products and demonstrate that the SCB content(i.e.,tertiary carbon density)significantly influences radical coupling during dynamic modification.Elevated tertiary carbon density,by introducing greater steric hindrance,suppresses radical coupling during dynamic modification,thereby reducing the efficiency of both crosslinking and peroxide fragment grafting.These findings provide new insights into the structure-reactivity relationships in peroxide-induced polyethylene modification and lay the foundation for tailoring material properties via dynamic processing.展开更多
Plant height(PH),primary lateral branch length(PBL),and branch number(BN)are architectural components impacting peanut pod yield,biomass production,and adaptivity to mechanical harvesting.In this study,a recombinant i...Plant height(PH),primary lateral branch length(PBL),and branch number(BN)are architectural components impacting peanut pod yield,biomass production,and adaptivity to mechanical harvesting.In this study,a recombinant inbred population consisting of 181 individual lines was used to determine genetic controls of PH,PBL,and BN across three environments.Phenotypic data collected from the population demonstrated continuous distributions and transgressive segregation patterns.Broad-sense heritability of PH,PBL,and BN was found to be 0.87,0.88,and 0.92,respectively.Unconditional individual environmental analysis revealed 35 additive QTLs with phenotypic variation explained(PVE)ranging from 4.57 to 21.68%.A two-round meta-analysis resulted in 24consensus and 19 unique QTLs.Five unique QTLs exhibited pleiotropic effects and their genetic bases(pleiotropy or tight linkage)were evaluated.A joint analysis was performed to estimate the QTL by environment interaction(QEI)effects on PH,PBL,and BN,collectively explaining phenotypic variations of 10.80,11.02,and 7.89%,respectively.We identified 3 major and stable QTL regions(uq9-3,uq10-2,and uq16-1)on chromosomes 9,10,and 16,spanning1.43-1.53 Mb genomic regions.Candidate genes involved in phytohormones biosynthesis,signaling,and cell wall development were proposed to regulate these morphological traits.These results provide valuable information for further genetic studies and the development of molecular markers applicable to peanut architecture improvement.展开更多
Branching is a critical aspect of plant architecture that significantly impacts the yield and adaptability of staple cereal crops like rice and wheat.Cereal crops develop tillers during the vegetative stage and panicl...Branching is a critical aspect of plant architecture that significantly impacts the yield and adaptability of staple cereal crops like rice and wheat.Cereal crops develop tillers during the vegetative stage and panicle or spike branches during the reproductive stage,respectively,both of which are significantly impacted by hormones and genetic factors.Tillering and panicle branching are closely interconnected and exhibit high environmental plasticity.Here,we summarize the recent progress in genetic,hormonal,and environmental factors regulation in the branching of rice and wheat.This review not only provides a comprehensive overview of the current knowledge on branching mechanisms in rice and wheat,but also explores the prospects for future research aimed at optimizing crop architecture for enhanced productivity.展开更多
Polybutene-1(PB-1) is a semi-crystalline polymer with excellent mechanical properties. However, its practical application is significantly hindered by the slow Form Ⅱ-Ⅰ transition, which can take up to several days ...Polybutene-1(PB-1) is a semi-crystalline polymer with excellent mechanical properties. However, its practical application is significantly hindered by the slow Form Ⅱ-Ⅰ transition, which can take up to several days to complete. While prior research established that long-chain branching(LCB) structures synthesized via ω-alkenylmethyldichlorosilane copolymerization-hydrolysis(ACH) chemistry markedly accelerate this transition, this work demonstrates that H-shaped LCB structures constructed through copolymerization with 1,9-decadiene exhibit the capability to facilitate Form Ⅱ-Ⅰ transition in most systems evaluated herein. However, low branching efficiency concurrently generates extended alkyl pendant chains, which impose pronounced steric-hindrance-driven suppression on the transition kinetics, thereby substantially diminishing the net acceleration effect of the LCB structures, even resulting in a net retardation effect in certain systems. Notably, a significant synergistic acceleration effect emerged between the H-shaped LCB structures and propylene comonomer units. These findings confirm that the H-shaped LCB structures play a role in promoting the Form II-I transformation process, which is independent of the synthetic pathways, thereby providing more strategies for addressing the long-standing processing problems of PB-1.展开更多
We study age-structured branching models with reproduction law depending on the remaining lifetime of the parent. The lifespan of an individual is determined at its birth and its remaining lifetime decreases at the un...We study age-structured branching models with reproduction law depending on the remaining lifetime of the parent. The lifespan of an individual is determined at its birth and its remaining lifetime decreases at the unit speed. The models, without or with immigration, are constructed as measure-valued processes by pathwise unique solutions of stochastic equations driven by time-space Poisson random measures. In the subcritical branching case, we give a sufficient condition for the ergodicity of the process with immigration. Two large number laws and a central limit theorem of the occupation times are proved.展开更多
The present study presents an assessment of the interrelations between long-chain branching,specific nucleation,and end-use properties of polypropylene blends:blends of linear polypropylene(L-PP)and long-chain branche...The present study presents an assessment of the interrelations between long-chain branching,specific nucleation,and end-use properties of polypropylene blends:blends of linear polypropylene(L-PP)and long-chain branched polypropylene(LCB-PP)modified by a specificβ-nucleating agent(NA).Specimens with various LCB-PP compositions with and without NA were prepared under complex flow fields by injection molding.Wide-angle X-ray scattering was employed to capture the X-ray patterns of both the skin and core of the specimens,determining the overall crystallinity and amounts of individual polymorphs.The increasing content of LCB-PP andγ-phase,at the same time,in the blends is reflected in both increasing crystallinity and improved mechanical properties,namely,yield stress and Young’s modulus.On the other hand,the composition of the blends had no significant effect on the impact strength,except for nucleated L-PP.It has been demonstrated that adding a relatively small amount of LCB-PP is sufficient to modify the mechanical properties of linear polypropylene.Even a very small amount of LCB-PP in the L-PP suppressed the effectiveness of NA.展开更多
本文研究了应急救援场景下的物资配送问题,考虑了在突发灾害导致道路中断和区域封锁的情况下,使用无人机进行救援物资配送的可行性。鉴于无人机在灵活性和快捷性方面的显著优势,本文主要探讨了具有能耗约束的应急救援无人机的配送模式...本文研究了应急救援场景下的物资配送问题,考虑了在突发灾害导致道路中断和区域封锁的情况下,使用无人机进行救援物资配送的可行性。鉴于无人机在灵活性和快捷性方面的显著优势,本文主要探讨了具有能耗约束的应急救援无人机的配送模式设计与优化问题。本文基于无人机的电量和配送响应水平,动态调整无人机的换电决策,以达成满足时效性要求的应急救援物资配送目标。其中,时效性反映了物资到达目标地点时的新鲜程度。本文首先建立了一个混合整数线性规划(mixed integer linear programming,MILP)模型,并开发了一个基于分支定价框架的精确算法。通过引入标签算法和启发式策略,本文进一步提升了通过分支定价算法解决子问题的效率。数值实验结果表明,本文设计的分支定价算法(branch and price algorithm,B&P)不仅能在保证时效性约束的前提下提供最优配送方案,还能在非常短的时间内得出符合决策要求的配送计划。此外,针对大规模无人机配送问题,本文设计了一个基于大邻域搜索的元启发式算法。实验结果显示,该算法在处理大规模问题时展现出了高效的求解能力,能够迅速提供实用的配送方案。展开更多
基金financially supported by the Science and Technology Project of PetroChina Company Limited,China(No.2022DJ6314)the National Natural Science Foundation of China(No.52173056)。
文摘Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials.In this study,four linear low-density polyethylenes(LLDPEs)with comparable molecular weights but different short-chain branch(SCB)contents(ranging of 5-66 per 1000 carbon atoms)were modified via dynamic melt mixing using 2 wt% benzoyl peroxide at 145℃ and 50 r/min for 30 min.The influence of SCB content on the processability and structure of the resulting products was systematically investigated.All modified products exhibited good melt processability with melt flow rates(MFR)ranging from 0.46 g/10min to 1.07 g/10min.Products derived from low-SCB LLDPEs showed a lower MFR,higher cross-linking content,a larger number of long-chain branches,and a higher degree of benzoyl grafting.In contrast,those produced from high-SCB LLDPEs exhibited improved processability,reduced cross-linking,fewer long-chain branches,and lower benzoyl grafting levels.A detailed structural investigation of the soluble and insoluble fractions,which were separated using trichlorobenzene fractionation,was conducted to analyze the structural features of various modified products and demonstrate that the SCB content(i.e.,tertiary carbon density)significantly influences radical coupling during dynamic modification.Elevated tertiary carbon density,by introducing greater steric hindrance,suppresses radical coupling during dynamic modification,thereby reducing the efficiency of both crosslinking and peroxide fragment grafting.These findings provide new insights into the structure-reactivity relationships in peroxide-induced polyethylene modification and lay the foundation for tailoring material properties via dynamic processing.
基金supported by the Natural Science Foundation of Shandong Province,China(ZR2022MC045)the National Natural Science Foundation of China(32001584,32201876)+2 种基金the Major Science and Technology Program of Xinjiang Uygur Autonomous Region,China(2022A02008-3)the Breeding Project from Department of Science&Technology of Shandong Province,China(2022LZGC007)the Agricultural Scientific and the Technological Innovation Project of Shandong Academy of Agricultural Sciences,China(CXGC2023A06,CXGC2023A39 and CXGC2023A46),and the Major Scientific and Technological Achievements Cultivation Program of Shandong Academy of Agricultural Sciences,China(CXGC2025E02)。
文摘Plant height(PH),primary lateral branch length(PBL),and branch number(BN)are architectural components impacting peanut pod yield,biomass production,and adaptivity to mechanical harvesting.In this study,a recombinant inbred population consisting of 181 individual lines was used to determine genetic controls of PH,PBL,and BN across three environments.Phenotypic data collected from the population demonstrated continuous distributions and transgressive segregation patterns.Broad-sense heritability of PH,PBL,and BN was found to be 0.87,0.88,and 0.92,respectively.Unconditional individual environmental analysis revealed 35 additive QTLs with phenotypic variation explained(PVE)ranging from 4.57 to 21.68%.A two-round meta-analysis resulted in 24consensus and 19 unique QTLs.Five unique QTLs exhibited pleiotropic effects and their genetic bases(pleiotropy or tight linkage)were evaluated.A joint analysis was performed to estimate the QTL by environment interaction(QEI)effects on PH,PBL,and BN,collectively explaining phenotypic variations of 10.80,11.02,and 7.89%,respectively.We identified 3 major and stable QTL regions(uq9-3,uq10-2,and uq16-1)on chromosomes 9,10,and 16,spanning1.43-1.53 Mb genomic regions.Candidate genes involved in phytohormones biosynthesis,signaling,and cell wall development were proposed to regulate these morphological traits.These results provide valuable information for further genetic studies and the development of molecular markers applicable to peanut architecture improvement.
基金funded by grants from the National Natural Science Foundation of China (31930006 to Y.W.)the National Key Research and Development Program of China (2022YFF1002903 to Y.W.)+1 种基金the Top Talents Program “One Case One Discussion”(Yishiyiyi to Y.W.)from Shandong provinceShandong Agricultural University Talent Introduction Start-up Fund (to N.Z.)
文摘Branching is a critical aspect of plant architecture that significantly impacts the yield and adaptability of staple cereal crops like rice and wheat.Cereal crops develop tillers during the vegetative stage and panicle or spike branches during the reproductive stage,respectively,both of which are significantly impacted by hormones and genetic factors.Tillering and panicle branching are closely interconnected and exhibit high environmental plasticity.Here,we summarize the recent progress in genetic,hormonal,and environmental factors regulation in the branching of rice and wheat.This review not only provides a comprehensive overview of the current knowledge on branching mechanisms in rice and wheat,but also explores the prospects for future research aimed at optimizing crop architecture for enhanced productivity.
基金financially supported by the National Natural Science Foundation of China (Nos. 52173013 and 52373015)。
文摘Polybutene-1(PB-1) is a semi-crystalline polymer with excellent mechanical properties. However, its practical application is significantly hindered by the slow Form Ⅱ-Ⅰ transition, which can take up to several days to complete. While prior research established that long-chain branching(LCB) structures synthesized via ω-alkenylmethyldichlorosilane copolymerization-hydrolysis(ACH) chemistry markedly accelerate this transition, this work demonstrates that H-shaped LCB structures constructed through copolymerization with 1,9-decadiene exhibit the capability to facilitate Form Ⅱ-Ⅰ transition in most systems evaluated herein. However, low branching efficiency concurrently generates extended alkyl pendant chains, which impose pronounced steric-hindrance-driven suppression on the transition kinetics, thereby substantially diminishing the net acceleration effect of the LCB structures, even resulting in a net retardation effect in certain systems. Notably, a significant synergistic acceleration effect emerged between the H-shaped LCB structures and propylene comonomer units. These findings confirm that the H-shaped LCB structures play a role in promoting the Form II-I transformation process, which is independent of the synthetic pathways, thereby providing more strategies for addressing the long-standing processing problems of PB-1.
基金supported by the National Key R&D Program of China(2020YFA0712901).
文摘We study age-structured branching models with reproduction law depending on the remaining lifetime of the parent. The lifespan of an individual is determined at its birth and its remaining lifetime decreases at the unit speed. The models, without or with immigration, are constructed as measure-valued processes by pathwise unique solutions of stochastic equations driven by time-space Poisson random measures. In the subcritical branching case, we give a sufficient condition for the ergodicity of the process with immigration. Two large number laws and a central limit theorem of the occupation times are proved.
文摘The present study presents an assessment of the interrelations between long-chain branching,specific nucleation,and end-use properties of polypropylene blends:blends of linear polypropylene(L-PP)and long-chain branched polypropylene(LCB-PP)modified by a specificβ-nucleating agent(NA).Specimens with various LCB-PP compositions with and without NA were prepared under complex flow fields by injection molding.Wide-angle X-ray scattering was employed to capture the X-ray patterns of both the skin and core of the specimens,determining the overall crystallinity and amounts of individual polymorphs.The increasing content of LCB-PP andγ-phase,at the same time,in the blends is reflected in both increasing crystallinity and improved mechanical properties,namely,yield stress and Young’s modulus.On the other hand,the composition of the blends had no significant effect on the impact strength,except for nucleated L-PP.It has been demonstrated that adding a relatively small amount of LCB-PP is sufficient to modify the mechanical properties of linear polypropylene.Even a very small amount of LCB-PP in the L-PP suppressed the effectiveness of NA.
文摘本文研究了应急救援场景下的物资配送问题,考虑了在突发灾害导致道路中断和区域封锁的情况下,使用无人机进行救援物资配送的可行性。鉴于无人机在灵活性和快捷性方面的显著优势,本文主要探讨了具有能耗约束的应急救援无人机的配送模式设计与优化问题。本文基于无人机的电量和配送响应水平,动态调整无人机的换电决策,以达成满足时效性要求的应急救援物资配送目标。其中,时效性反映了物资到达目标地点时的新鲜程度。本文首先建立了一个混合整数线性规划(mixed integer linear programming,MILP)模型,并开发了一个基于分支定价框架的精确算法。通过引入标签算法和启发式策略,本文进一步提升了通过分支定价算法解决子问题的效率。数值实验结果表明,本文设计的分支定价算法(branch and price algorithm,B&P)不仅能在保证时效性约束的前提下提供最优配送方案,还能在非常短的时间内得出符合决策要求的配送计划。此外,针对大规模无人机配送问题,本文设计了一个基于大邻域搜索的元启发式算法。实验结果显示,该算法在处理大规模问题时展现出了高效的求解能力,能够迅速提供实用的配送方案。
