As urbanization accelerates globally,air pollution-particularly PM_(2.5)-is becoming an increasingly significant threat,not only to public health but also the environment.In-depth research on the impact of China’s Ze...As urbanization accelerates globally,air pollution-particularly PM_(2.5)-is becoming an increasingly significant threat,not only to public health but also the environment.In-depth research on the impact of China’s Zero Waste City pilot policy on PM_(2.5)concentration offers valuable insights into the policy’s effectiveness and provides a potential model for environmental governance worldwide.This study employs panel data from 293 Chinese cities from 2014 to 2022 to systematically analyze the impact of the Zero-Waste City policy on PM_(2.5)concentration using a difference-in-differences model.The findings indicate that the policy not only directly reduces PM_(2.5)concentration but also indirectly curbs PM_(2.5)emissions by enhancing green innovation and green economic efficiency.Moreover,the policy’s effects are found to be positively moderated by urban energy dependence and digital financial inclusion,while they are negatively moderated by the government debt ratio.Based on these findings,this study suggests that cities should actively develop their digital economy,reduce government debt,promote green innovation,and improve green economic efficiency,as doing so will enhance their implementation of environmental policies and promote sustainable urban development.展开更多
Moisture-responsive actuators are widely used as energy-harvesting devices due to their excellent ability to spontaneously and continuously convert external energy into kinetic energy.However,it remains a challenge to...Moisture-responsive actuators are widely used as energy-harvesting devices due to their excellent ability to spontaneously and continuously convert external energy into kinetic energy.However,it remains a challenge to sustainably synthesize moisture-driven actuators.Here,we present a sustainable zero-waste emission methodology to prepare soft actuators using carbon nano-powders and biodegradable polymers through a water evaporation method.Due to the water solubility and recyclability of the matrixes employed here,the entire synthetic process achieves zero-waste emission.Our composite films featured strong figures of merit and capabilities with a 250◦maximum bending angle under 90%relative humidity.Programmable motions and intelligent bionic applications,including walkers,smart switches,robotic arms,flexible excavators,and hand-shaped actuators,were further achieved by modulating the geometry of the actuators.This sustainable method for actuators’fabrication has great potential in large-scale productions and applications due to its advantages of zero-waste emission manufacturing,excellent recyclability,inherent adaptive integration,and low cost.展开更多
This research aimed to develop a prototype process for hydrogen production from Napier grass(NG)and oil palm frond(OPF).First,biohydrogen production was investigated in batch experiments using either the simultaneous ...This research aimed to develop a prototype process for hydrogen production from Napier grass(NG)and oil palm frond(OPF).First,biohydrogen production was investigated in batch experiments using either the simultaneous saccharification and fermentation(SSF)process or the pre-hydrolysis and fermentation(pre-HF)process under different NG to OPF ratios.The proportions of NG:OPF of 2.5:7.5,5.0:5.0,and 7.5:2.5 g-VS/L were tested in both SSF and pre-HF.The results showed that the proportion of NG:OPF of 5.0:5.0 g-VS/L(ratio of 1:1)had the highest hydrogen production in both the SSF and pre-HF processes,with hydrogen production of 370±21 mL-H_(2)/L and 993±64 mL-H_(2)/L,respectively.Among these,pre-HF showed higher performance.Next,a semicontinuous experiment in a 100 L continuous stirred tank reactor(CSTR)with a pre-HF process and NG:OPF of 5.0:5.0 g-VS/L at hydraulic retention times(HRTs)of 4 and 3 days,with and without trace metal supple-mentation,was conducted.The highest hydrogen yield,50.1±3.4 mL-H_(2)/g-VS,was found at an HRT of 3 days with trace metal supplementation.Key microbes,including Lactococcus sp.,Bacteroides sp.,Dysgonomonas sp.,and Enterobacter sp.,showed increased abundance,improving hydrogen production from NG and OPF.The addition of trace elements significantly altered essential enzymes like 6-phosphofructokinase,which is crucial for forming pyruvate in hydrogen production.The medium-based economic analysis revealed that the pre-HF process with trace elements resulted in an overall hydrogen production of 9.32 m3,an improvement of 16.6% compared to the 7.99 m3 obtained under pre-HF without adding trace elements.Consequently,the Economic Yield(EY)of pre-HF without trace element addition was 0.030 USD-H_(2)/USD-medium,which was enhanced to 0.035 USD-H_(2)/USD-medium by adding trace elements.展开更多
基金The authors declare that fund support was received from National Social Science Fund of China[Grant No.23BJL010].
文摘As urbanization accelerates globally,air pollution-particularly PM_(2.5)-is becoming an increasingly significant threat,not only to public health but also the environment.In-depth research on the impact of China’s Zero Waste City pilot policy on PM_(2.5)concentration offers valuable insights into the policy’s effectiveness and provides a potential model for environmental governance worldwide.This study employs panel data from 293 Chinese cities from 2014 to 2022 to systematically analyze the impact of the Zero-Waste City policy on PM_(2.5)concentration using a difference-in-differences model.The findings indicate that the policy not only directly reduces PM_(2.5)concentration but also indirectly curbs PM_(2.5)emissions by enhancing green innovation and green economic efficiency.Moreover,the policy’s effects are found to be positively moderated by urban energy dependence and digital financial inclusion,while they are negatively moderated by the government debt ratio.Based on these findings,this study suggests that cities should actively develop their digital economy,reduce government debt,promote green innovation,and improve green economic efficiency,as doing so will enhance their implementation of environmental policies and promote sustainable urban development.
基金Royal Society Research Grant,Grant/Award Number:RGS\R1\201071QMUL-CSC(China Scholarship Council)。
文摘Moisture-responsive actuators are widely used as energy-harvesting devices due to their excellent ability to spontaneously and continuously convert external energy into kinetic energy.However,it remains a challenge to sustainably synthesize moisture-driven actuators.Here,we present a sustainable zero-waste emission methodology to prepare soft actuators using carbon nano-powders and biodegradable polymers through a water evaporation method.Due to the water solubility and recyclability of the matrixes employed here,the entire synthetic process achieves zero-waste emission.Our composite films featured strong figures of merit and capabilities with a 250◦maximum bending angle under 90%relative humidity.Programmable motions and intelligent bionic applications,including walkers,smart switches,robotic arms,flexible excavators,and hand-shaped actuators,were further achieved by modulating the geometry of the actuators.This sustainable method for actuators’fabrication has great potential in large-scale productions and applications due to its advantages of zero-waste emission manufacturing,excellent recyclability,inherent adaptive integration,and low cost.
基金co-funded by the National Research Council of Thailand(NRCT)and the Electricity Generating Authority of Thailand(EGAT)(Grant No.N25D650029)partially supported by the National Research Council of Thailand(NRCT)(Grant No.N42A670487).
文摘This research aimed to develop a prototype process for hydrogen production from Napier grass(NG)and oil palm frond(OPF).First,biohydrogen production was investigated in batch experiments using either the simultaneous saccharification and fermentation(SSF)process or the pre-hydrolysis and fermentation(pre-HF)process under different NG to OPF ratios.The proportions of NG:OPF of 2.5:7.5,5.0:5.0,and 7.5:2.5 g-VS/L were tested in both SSF and pre-HF.The results showed that the proportion of NG:OPF of 5.0:5.0 g-VS/L(ratio of 1:1)had the highest hydrogen production in both the SSF and pre-HF processes,with hydrogen production of 370±21 mL-H_(2)/L and 993±64 mL-H_(2)/L,respectively.Among these,pre-HF showed higher performance.Next,a semicontinuous experiment in a 100 L continuous stirred tank reactor(CSTR)with a pre-HF process and NG:OPF of 5.0:5.0 g-VS/L at hydraulic retention times(HRTs)of 4 and 3 days,with and without trace metal supple-mentation,was conducted.The highest hydrogen yield,50.1±3.4 mL-H_(2)/g-VS,was found at an HRT of 3 days with trace metal supplementation.Key microbes,including Lactococcus sp.,Bacteroides sp.,Dysgonomonas sp.,and Enterobacter sp.,showed increased abundance,improving hydrogen production from NG and OPF.The addition of trace elements significantly altered essential enzymes like 6-phosphofructokinase,which is crucial for forming pyruvate in hydrogen production.The medium-based economic analysis revealed that the pre-HF process with trace elements resulted in an overall hydrogen production of 9.32 m3,an improvement of 16.6% compared to the 7.99 m3 obtained under pre-HF without adding trace elements.Consequently,the Economic Yield(EY)of pre-HF without trace element addition was 0.030 USD-H_(2)/USD-medium,which was enhanced to 0.035 USD-H_(2)/USD-medium by adding trace elements.
