Poly(butylene adipate-terephthalate)(PBAT),as one of the most common and promising biodegradable plastics,has been widely used in agriculture,packaging,and other industries due to its strong biodegradability propertie...Poly(butylene adipate-terephthalate)(PBAT),as one of the most common and promising biodegradable plastics,has been widely used in agriculture,packaging,and other industries due to its strong biodegradability properties.It is well known that PBAT suffers a series of natural weathering,mechanical wear,hydrolysis,photochemical transformation,and other abiotic degradation processes before being biodegraded.Therefore,it is particularly important to understand the role of abiotic degradation in the life cycle of PBAT.Since the abiotic degradation of PBAT has not been systematically summarized,this review aims to summarize the mechanisms and main factors of the three major abiotic degradation pathways(hydrolysis,photochemical transformation,and thermochemical degradation)of PBAT.It was found that all of them preferentially destroy the chemical bonds with higher energy(especially C-O and C=O)of PBAT,which eventually leads to the shortening of the polymer chain and then leads to reduction in molecular weight.The main factors affecting these abiotic degradations are closely related to the energy or PBAT structure.These findings provide important theoretical and practical guidance for identifying effective methods for PBAT waste management and proposing advanced schemes to regulate the degradation rate of PBAT.展开更多
Metal halide perovskite solar cells(PSCs) have attracted extensive research interest for next-generation solution-processed photovoltaic devices because of their high solar-to-electric power conversion efficiency(PCE)...Metal halide perovskite solar cells(PSCs) have attracted extensive research interest for next-generation solution-processed photovoltaic devices because of their high solar-to-electric power conversion efficiency(PCE)and low fabrication cost. Although the world's best PSC successfully achieves a considerable PCE of over 20% within a very limited timeframe after intensive efforts, the stability, high cost, and up-scaling of PSCs still remain issues. Recently, inorganic perovskite material, CsPbBr_3, is emerging as a promising photo-sensitizer with excellent durability and thermal stability, but the efficiency is still embarrassing. In this work, we intend to address these issues by exploiting CsPbBr_3 as light absorber, accompanied by using Cu-phthalocyanine(CuPc) as hole transport material(HTM) and carbon as counter electrode. The optimal device acquires a decent PCE of 6.21%, over 60% higher than those of the HTM-free devices. The systematic characterization and analysis reveal a more effective charge transfer process and a suppressed charge recombination in PSCs after introducing CuPc as hole transfer layer. More importantly, our devices exhibit an outstanding durability and a promising thermal stability, making it rather meaningful in future fabrication and application of PSCs.展开更多
Sina Weibo,an online social network site,has gained popularity but lost it in recent years.Now we are still curious on the number of posts in Sina Weibo in its golden age.Besides checking this number in Sina’s operat...Sina Weibo,an online social network site,has gained popularity but lost it in recent years.Now we are still curious on the number of posts in Sina Weibo in its golden age.Besides checking this number in Sina’s operating results,we aim to estimate and verify this number through measurement by using statistical techniques.Existing approaches on measurement always rely on the supported streaming application programming interface(API)which provides proportional sampling.However no such API is available for Sina Weibo.Instead,Sina provides a public timeline API which provides non-proportional sampling but always returns a(nearly)fixed number of s amples.In this paper,we present a novel method utilizing this API and estimate the number of posts in Sina Weibo in its golden age.展开更多
基金supported by the National Key R&D Program of China(No.2022YFC3901800)the National Natural Science Foundation of China(No.22176041)Guangzhou Science and Technology Planning Project(No.2023A04J0918)。
文摘Poly(butylene adipate-terephthalate)(PBAT),as one of the most common and promising biodegradable plastics,has been widely used in agriculture,packaging,and other industries due to its strong biodegradability properties.It is well known that PBAT suffers a series of natural weathering,mechanical wear,hydrolysis,photochemical transformation,and other abiotic degradation processes before being biodegraded.Therefore,it is particularly important to understand the role of abiotic degradation in the life cycle of PBAT.Since the abiotic degradation of PBAT has not been systematically summarized,this review aims to summarize the mechanisms and main factors of the three major abiotic degradation pathways(hydrolysis,photochemical transformation,and thermochemical degradation)of PBAT.It was found that all of them preferentially destroy the chemical bonds with higher energy(especially C-O and C=O)of PBAT,which eventually leads to the shortening of the polymer chain and then leads to reduction in molecular weight.The main factors affecting these abiotic degradations are closely related to the energy or PBAT structure.These findings provide important theoretical and practical guidance for identifying effective methods for PBAT waste management and proposing advanced schemes to regulate the degradation rate of PBAT.
基金the financial support from the National Natural Science Foundation of China (Grant Nos. 51675210 and 51675209)the China Postdoctoral Science Foundation (Grant No. 2016M602283)
文摘Metal halide perovskite solar cells(PSCs) have attracted extensive research interest for next-generation solution-processed photovoltaic devices because of their high solar-to-electric power conversion efficiency(PCE)and low fabrication cost. Although the world's best PSC successfully achieves a considerable PCE of over 20% within a very limited timeframe after intensive efforts, the stability, high cost, and up-scaling of PSCs still remain issues. Recently, inorganic perovskite material, CsPbBr_3, is emerging as a promising photo-sensitizer with excellent durability and thermal stability, but the efficiency is still embarrassing. In this work, we intend to address these issues by exploiting CsPbBr_3 as light absorber, accompanied by using Cu-phthalocyanine(CuPc) as hole transport material(HTM) and carbon as counter electrode. The optimal device acquires a decent PCE of 6.21%, over 60% higher than those of the HTM-free devices. The systematic characterization and analysis reveal a more effective charge transfer process and a suppressed charge recombination in PSCs after introducing CuPc as hole transfer layer. More importantly, our devices exhibit an outstanding durability and a promising thermal stability, making it rather meaningful in future fabrication and application of PSCs.
基金This work was supported in part by the National Natural Science Foundation of China under Grants 61602111,61502099,61502100,61532013the Jiangsu Provincial Natural Science Foundation of China under Grants BK20150628,BK20150637+2 种基金the Jiangsu Provincial Scientific and Technological Achievements Transfer Fund,and by the Jiangsu Provincial Key Laboratory of Network and Information Security under Grant BM2003201the Key Laboratory of Computer Network and Information Integration of Ministry of Education of China under Grant 93K-9Collaborative Innovation Center of Novel Software Technology and Industrialization.
文摘Sina Weibo,an online social network site,has gained popularity but lost it in recent years.Now we are still curious on the number of posts in Sina Weibo in its golden age.Besides checking this number in Sina’s operating results,we aim to estimate and verify this number through measurement by using statistical techniques.Existing approaches on measurement always rely on the supported streaming application programming interface(API)which provides proportional sampling.However no such API is available for Sina Weibo.Instead,Sina provides a public timeline API which provides non-proportional sampling but always returns a(nearly)fixed number of s amples.In this paper,we present a novel method utilizing this API and estimate the number of posts in Sina Weibo in its golden age.
