In this paper the problem of a circular beam subjected to radial impact by a rigid mass at its lip in its own plane is investigaleil on the basis of rigid-perfectly plastic assumption. The analytical solution of the p...In this paper the problem of a circular beam subjected to radial impact by a rigid mass at its lip in its own plane is investigaleil on the basis of rigid-perfectly plastic assumption. The analytical solution of the particle velocities is obtained as the junction of travelling plastic hinge location. Ky analysing the solution, some special properties oj circular beam problem are found.展开更多
Plastic pollution is global concern, affecting most aspects of global food production systems. Plasticulture, a practice used in agriculture to improve crop quality and quantity, among other factors, is a significant ...Plastic pollution is global concern, affecting most aspects of global food production systems. Plasticulture, a practice used in agriculture to improve crop quality and quantity, among other factors, is a significant source of plastic pollution. This review examines the extent of plasticulture in China, the implications of the practice across decades of use and the legislative instruments used to resolve those issues. It briefly assesses the effectiveness of these policies and proposes possible future innovations to promote increases in long-term food and eco-security, where sustainable plasticulture is a key agent for change. While plasticulture has increased agricultural productivity in growth-limiting conditions, plastic pollution in agricultural soils has become acute in China. Consequently, plastic pollution is having deleterious effects on soil health and in turn, crop productivity in China. Plastic pollution in agriculture is a multifaceted issue and so proposed solutions should be informed by this complexity. Current measures do not reflect a holistic approach to solving this socioecological challenge and adopt a top-down approach, with little or no supportive mechanisms. Future recommendations need to consider the particular set of conditions that influence the production, use and end-of-life management of agriplastics,specific to the environmental, economic and social conditions in each location.展开更多
The development of modern society is closely related to polymer materials.However,the improper disposal of the polymer wastes not only squanders resources but also intensifies the environmental issues,despite that ene...The development of modern society is closely related to polymer materials.However,the improper disposal of the polymer wastes not only squanders resources but also intensifies the environmental issues,despite that energy recovery,physical recycling and chemical recycling pathways have been developed to tackle the recycle and reuse of polymers.Among them,chemical recycling is considered as the most pivotal solution,as it can depolymerize the polymer wastes back to monomers,which then repolymerize into polymer materials.Recently,remarkable progress has been made in the development of chemically recyclable polymers through monomer design to shift“polymerization-depolymerization”equilibrium to realize the selective depolymerization of the polymers into monomers,and to achieve chemical recycling closed-loop.This article reviews the closed-loop polymers such as polyesters,polycarbonates,sulfur-containing polymers,vinyl monomer-based polymers as well as other types of polymers.Moreover,the challenges and prospects in this field are also discussed.展开更多
文摘In this paper the problem of a circular beam subjected to radial impact by a rigid mass at its lip in its own plane is investigaleil on the basis of rigid-perfectly plastic assumption. The analytical solution of the particle velocities is obtained as the junction of travelling plastic hinge location. Ky analysing the solution, some special properties oj circular beam problem are found.
基金funded by BBSRC (EAA7536XS04)Waitrose Agronomy Group as part of the Waitrose Collaborative Training Partnership。
文摘Plastic pollution is global concern, affecting most aspects of global food production systems. Plasticulture, a practice used in agriculture to improve crop quality and quantity, among other factors, is a significant source of plastic pollution. This review examines the extent of plasticulture in China, the implications of the practice across decades of use and the legislative instruments used to resolve those issues. It briefly assesses the effectiveness of these policies and proposes possible future innovations to promote increases in long-term food and eco-security, where sustainable plasticulture is a key agent for change. While plasticulture has increased agricultural productivity in growth-limiting conditions, plastic pollution in agricultural soils has become acute in China. Consequently, plastic pollution is having deleterious effects on soil health and in turn, crop productivity in China. Plastic pollution in agriculture is a multifaceted issue and so proposed solutions should be informed by this complexity. Current measures do not reflect a holistic approach to solving this socioecological challenge and adopt a top-down approach, with little or no supportive mechanisms. Future recommendations need to consider the particular set of conditions that influence the production, use and end-of-life management of agriplastics,specific to the environmental, economic and social conditions in each location.
基金supported by the National Natural Science Foundation of China(22225104,22071077 and 92356302)China Postdoctoral Science Foundation(2022TQ0115 and 2022M711297).
文摘The development of modern society is closely related to polymer materials.However,the improper disposal of the polymer wastes not only squanders resources but also intensifies the environmental issues,despite that energy recovery,physical recycling and chemical recycling pathways have been developed to tackle the recycle and reuse of polymers.Among them,chemical recycling is considered as the most pivotal solution,as it can depolymerize the polymer wastes back to monomers,which then repolymerize into polymer materials.Recently,remarkable progress has been made in the development of chemically recyclable polymers through monomer design to shift“polymerization-depolymerization”equilibrium to realize the selective depolymerization of the polymers into monomers,and to achieve chemical recycling closed-loop.This article reviews the closed-loop polymers such as polyesters,polycarbonates,sulfur-containing polymers,vinyl monomer-based polymers as well as other types of polymers.Moreover,the challenges and prospects in this field are also discussed.
