Against the backdrop of the global push for environmental protection and the reduction of plastic pollution,the research and development of alternatives to daily disposable plastic products such as straws have become ...Against the backdrop of the global push for environmental protection and the reduction of plastic pollution,the research and development of alternatives to daily disposable plastic products such as straws have become a hot topic in the environmental protection field.Traditional plastic straws are difficult to degrade,imposing a severe burden on the environment.Meanwhile,existing alternatives like paper straws and PLA(polylactic acid)straws also have numerous drawbacks.展开更多
Conventional bioplastic production from seaweed often relies on extraction processes that are costly,time-consuming,and yield limited product.This study presents a direct fabrication method using Gracilaria sp.,a red ...Conventional bioplastic production from seaweed often relies on extraction processes that are costly,time-consuming,and yield limited product.This study presents a direct fabrication method using Gracilaria sp.,a red seaweed rich in polysaccharides,to produce bioplastic films without the need for extraction.Sorbitol was incorporated as a plasticizer at concentrations of 0%–10%(w/w)to modify film characteristics.Thermal analysis revealed improved stability at moderate sorbitol levels(5%–7%),while excessive plasticizer slightly reduced thermal resistance.Mechanical testing showed that sorbitol increased film flexibility and elongation at break,though tensile strength and stiffness declined.Tear strength followed a non-linear trend,with improvement observed at higher sorbitol concentrations.Seal strength also increased,peaking at 7%,indicating stronger interfacial bonding between film layers.Biodegradation tests demonstrated accelerated decomposition with increased sorbitol content,achieving complete degradation within 30 days at 10% concentration.Color analysis showed increased brightness and reduced yellowing,enhancing the visual quality of the films.These results confirm that direct conversion of bioplastic is both feasible and effective.Sorbitol plays a key role in tuning film properties,offering a low-cost,scalable pathway to biodegradable materials suitable for environmentally friendly packaging applications.展开更多
Mechanical engineering structures and structural components are often subjected to cyclic thermomechanical loading which stresses their material beyond its elastic limits well inside the inelastic regime.Depending on ...Mechanical engineering structures and structural components are often subjected to cyclic thermomechanical loading which stresses their material beyond its elastic limits well inside the inelastic regime.Depending on the level of loading inelastic strains may lead either to failure,due to low cycle fatigue or ratcheting,or to safety,through elastic shakedown.Thus,it is important to estimate the asymptotic stress state of such structures.This state may be determined by cumbersome incremental time-stepping calculations.Direct methods,alternatively,have big computational advantages as they focus on the characteristics of these states and try to establish them,in a direct way,right from the beginning of the calculations.Among the very few such general-purpose direct methods,a powerful direct method which has been called RSDM has appeared in the literature.The method may directly predict any asymptotic state when the exact time history of the loading is known.The advantage of the method is due to the fact that it addresses the physics of the asymptotic cycle and exploits the cyclic nature of its expected residual stress distribution.Based on RSDM a method for the shakedown analysis of structures,called RSDM-S has also been developed.Despite most direct methods for shakedown,RSDM-S does not need an optimization algorithm for its implementation.Both RSDM and RSDM-S may be implemented in any Finite Element Code.A thorough review of both these methods,together with examples of implementation are presented herein.展开更多
Single-use plastics are often used once or cannot be reused for extended periods.They are widely consumed with the rapid development of social economy.The waste generated by single-use plastics threatens ecosystem hea...Single-use plastics are often used once or cannot be reused for extended periods.They are widely consumed with the rapid development of social economy.The waste generated by single-use plastics threatens ecosystem health by entering the environment and ultimately restricts sustainable human development.The innovation of sustainable and environmentally friendly single-use plastic alternative materials and the joint participation of governments,enterprises and the public are promising technologies and management approaches that can solve the problem of single-use plastics wastes.The development of single-use plastic alternative products can be promoted fundamentally only by improving relevant legislation and standards,providing differentiated industrial policies,encouraging scientific and technological innovation and expanding public participation.展开更多
文摘Against the backdrop of the global push for environmental protection and the reduction of plastic pollution,the research and development of alternatives to daily disposable plastic products such as straws have become a hot topic in the environmental protection field.Traditional plastic straws are difficult to degrade,imposing a severe burden on the environment.Meanwhile,existing alternatives like paper straws and PLA(polylactic acid)straws also have numerous drawbacks.
基金funded by IAEA Coordinated Research Project F22081.
文摘Conventional bioplastic production from seaweed often relies on extraction processes that are costly,time-consuming,and yield limited product.This study presents a direct fabrication method using Gracilaria sp.,a red seaweed rich in polysaccharides,to produce bioplastic films without the need for extraction.Sorbitol was incorporated as a plasticizer at concentrations of 0%–10%(w/w)to modify film characteristics.Thermal analysis revealed improved stability at moderate sorbitol levels(5%–7%),while excessive plasticizer slightly reduced thermal resistance.Mechanical testing showed that sorbitol increased film flexibility and elongation at break,though tensile strength and stiffness declined.Tear strength followed a non-linear trend,with improvement observed at higher sorbitol concentrations.Seal strength also increased,peaking at 7%,indicating stronger interfacial bonding between film layers.Biodegradation tests demonstrated accelerated decomposition with increased sorbitol content,achieving complete degradation within 30 days at 10% concentration.Color analysis showed increased brightness and reduced yellowing,enhancing the visual quality of the films.These results confirm that direct conversion of bioplastic is both feasible and effective.Sorbitol plays a key role in tuning film properties,offering a low-cost,scalable pathway to biodegradable materials suitable for environmentally friendly packaging applications.
文摘Mechanical engineering structures and structural components are often subjected to cyclic thermomechanical loading which stresses their material beyond its elastic limits well inside the inelastic regime.Depending on the level of loading inelastic strains may lead either to failure,due to low cycle fatigue or ratcheting,or to safety,through elastic shakedown.Thus,it is important to estimate the asymptotic stress state of such structures.This state may be determined by cumbersome incremental time-stepping calculations.Direct methods,alternatively,have big computational advantages as they focus on the characteristics of these states and try to establish them,in a direct way,right from the beginning of the calculations.Among the very few such general-purpose direct methods,a powerful direct method which has been called RSDM has appeared in the literature.The method may directly predict any asymptotic state when the exact time history of the loading is known.The advantage of the method is due to the fact that it addresses the physics of the asymptotic cycle and exploits the cyclic nature of its expected residual stress distribution.Based on RSDM a method for the shakedown analysis of structures,called RSDM-S has also been developed.Despite most direct methods for shakedown,RSDM-S does not need an optimization algorithm for its implementation.Both RSDM and RSDM-S may be implemented in any Finite Element Code.A thorough review of both these methods,together with examples of implementation are presented herein.
基金the National Natural Science Foundation of China(Grant Nos.41977030 and 42030704)the National Key Research and Development Program of China(No.2019YFC1906704).
文摘Single-use plastics are often used once or cannot be reused for extended periods.They are widely consumed with the rapid development of social economy.The waste generated by single-use plastics threatens ecosystem health by entering the environment and ultimately restricts sustainable human development.The innovation of sustainable and environmentally friendly single-use plastic alternative materials and the joint participation of governments,enterprises and the public are promising technologies and management approaches that can solve the problem of single-use plastics wastes.The development of single-use plastic alternative products can be promoted fundamentally only by improving relevant legislation and standards,providing differentiated industrial policies,encouraging scientific and technological innovation and expanding public participation.
