A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface,which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate.The resu...A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface,which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate.The results show that cold-pressing produces intense plastic deformation near the corrugated surface of the Al plate,which promotes dynamic recrystallization of the Al substrate near the interface during the subsequent hot-pressing.In addition,the initial corrugation on the surface of the Al plate also changes the local stress state near the interface during hot pressing,which has a large effect on the texture components of the substrates near the corrugated interface.The construction of the corrugated interface can greatly enhance the shear strength by 2−4 times due to the increased contact area and the strong“mechanical gearing”effect.Moreover,the mechanical properties are largely depended on the orientation relationship between corrugated direction and loading direction.展开更多
Aggregation-induced emission(AIE)polymers have been extensively studied;however,the integration of AIE units into polyelectrolytes remains largely limited by the laborious multistep synthesis of pre-designed emissive ...Aggregation-induced emission(AIE)polymers have been extensively studied;however,the integration of AIE units into polyelectrolytes remains largely limited by the laborious multistep synthesis of pre-designed emissive monomers.Herein,we report a one-pot multicomponent polymerization method that directly produces main-chain charged polyelectrolytes with intrinsic AIE characteristics from non-emissive building blocks.By optimizing the monomer structures and reaction conditions,a series of soluble high-molecular-weight polymers with welldefined backbones were obtained in high yields.The resulting polyelectrolytes displayed robust AIE behavior,exhibiting fluorescence enhancement up to about 60-fold in an aqueous environment,and maintained excellent thermal stability.Owing to their cationic backbones,these polymers interact strongly with microbial surfaces and exhibit remarkable antimicrobial activities.This study establishes a synthetically efficient route to AIE polyelectrolytes and highlights their potential applications as multifunctional materials for bioimaging,antimicrobial therapy,and other applications.展开更多
Laminated metal composites(LMCs) are a unique composite material and have great application prospects in automobiles, ships, aircraft,and other manufacturing industries. As lightweight materials, the Mg/Al LMCs are ex...Laminated metal composites(LMCs) are a unique composite material and have great application prospects in automobiles, ships, aircraft,and other manufacturing industries. As lightweight materials, the Mg/Al LMCs are expected to combine the advantages of both Mg and Al alloys to broaden their application prospects. Roll-bonding is the most popular process for the fabrication of Mg/Al LMCs due to high production efficiency and good product quality stability. The roll-bonding process involves the deformation of the substrates and the formation of the interfacial diffusion layer. The latter will directly determine the interface bonding strength of Mg/Al LMCs. Bonding strength is very sensitive to the thickness of the reaction layer in the diffusion layer. When the thickness of the reaction layer exceeds 5 μm, the bonding strength decreases sharply. Therefore, controlling the thickness of the reaction layer is very important for the design of rolling parameters.The latest research also showed that the addition of intermediate layer metal and the construction of three-dimensional interfaces can further improve the interface bonding strength. How to apply these methods to roll-bonding is the focus of future research. Recently, a new rolling technique, corrugated roll/plat roll rolling+flat roll/flat roll rolling has been developed to fabricate Mg/Al LMCs. It can effectively promote the deformation of the hard layer and generate a wavy interface, resulting in the enhancement of the bonding quality and rolling quality.In the current review, the effects of rolling parameters and subsequent annealing on the interface structure of Mg/Al LMCs were elaborated in detail. The application of some special rolling techniques in the preparation of Mg/Al LMCs was also summarized. The latest research results on the relationship between interface structure and mechanical properties of Mg/Al LMCs were reviewed. Finally, further research directions in this field were proposed.展开更多
Using boron powder as additive, the preparation of zirconium diboride(ZrB 2) by carbothermal reduction was investigated. The results show that the carbothermal reduction cannot be completely done until the temperature...Using boron powder as additive, the preparation of zirconium diboride(ZrB 2) by carbothermal reduction was investigated. The results show that the carbothermal reduction cannot be completely done until the temperature is more than 1900 ℃. The ZrB2 particles prepared without boron(B) additive at 1900 ℃ for 3 h are rodlike and show a preferential grain growth along [001] direction. B additive changes the heat effect of the raw materials. With B additive, the morphology of ZrB2 particles turns to be regular shape. The average particle size is about 3.6 μm with 2.5 wt% B additives. With more B additive, the shape of particles turns to be round like and the average particle size is decreased to 2.3 μm when 5 wt% B is added. The existence of oxides in grain boundary is a key factor to keep ZrB2 ceramic from deep densification. Using ZrB2 powder prepared with 5 wt% B additives, by controlling carbon content in ZrB2 powder, ZrB2 ceramic with 93%relative density is hot-pressed.展开更多
Background: Carbon sequestration through recommended forest management practices is an ecosystem service that helps mitigate climate change and its impacts while generating carbon credits for forestland owners to sell...Background: Carbon sequestration through recommended forest management practices is an ecosystem service that helps mitigate climate change and its impacts while generating carbon credits for forestland owners to sell in cap-and-trade programs. The California’s cap-and-trade program (California’s carbon market hereafter) allows forestland owners from any part of the contiguous United States to supply carbon credits to compliance entities. In this study, we estimate South Carolina (SC) private forestland owners’willingness to accept compensations to participate in the California’s carbon market using a contingent valuation method. Results: We estimate forestland owners’mean willingness to accept as$67 per acre per year. Our results reveal higher probability of participation of forestland owners with interests in preserving forest ecosystems than those who do not. Additionally, forestland owners who trust in information about climate change from scientists or government are willing to participate more than those who do not. Conclusions: Various factors hinder landowners’ability to participate in carbon markets. Forestland owners in SC consider legislative uncertainty and long-time commitment as the main barriers to participation in California’s carbon market. From this research, average forestland tenure in SC is 27 years, which is far less than the 100-year time commitment of the California’s carbon market. Of those who agreed to participate, choosing between adopting and not adopting any of the three main forest management practices in the California’s carbon market:28% are likely to adopt improved forest management (IFM) practices, 24% are likely to adopt reforestation due to understocked forestlands, and 14% are likely to adopt avoided conversion. In another development, the concept of aggregation has dominated discussions in the California’s carbon market of late. It is an advocacy to include small-scale forestlands in the California’s carbon market. To aggregate, different forestland owners will combine their forestlands to participate. We find that 79% of SC forestland owners are willing to aggregate to participate. However, this research is unable to determine how much total forestland is available in SC for carbon market. We recommend future research in the State on forestland owners’participation in carbon market should consider evaluating forestland availability.展开更多
Low-cost and efficient oxygen reduction reaction(ORR)electrocatalysts are the key to developing Zn-air batteries for renewable energy storage.Herein,the Mn-N-P doped carbon sphere was prepared through polymerization o...Low-cost and efficient oxygen reduction reaction(ORR)electrocatalysts are the key to developing Zn-air batteries for renewable energy storage.Herein,the Mn-N-P doped carbon sphere was prepared through polymerization of hexachlorotripolyphosphazene(HCCP)and phloroglucinol,and then followed the calcination at 900°C.Theory calculations demonstrated the introduction of Mn in N-P doped carbon could lower the dissociation barrier of O2into O*and promote the ORR through a 4e-pathway.The asprepared catalysts exhibited a half-wave potential of 0.82 V vs.RHE and limiting current density of 5.2 m A/cm^(2)toward ORR,which was comparable to those of the commercial Pt/C catalysts.In addition,Zn-air batteries with 0.05 Mn-N-P-C catalysts showed a high specific capacity of 830 m Ah/gZnand excellent cycle stability.This facile approach demonstrated herein could be a solution to develop optimum non-precious metal catalysts for the application in cathodes of proton exchange membrane fuel cells.This study also provides new insight to design the catalysts of multi-heteroatom coordinated metal in the carbon matrix for both fundamental researches and practical applications.展开更多
Dear Editor,Life can utilize energy with high efficiency,especially with the help of aerobic respiration,where the tricarboxylic acid(TCA)cycle acts as an important metabolic engine for mitochondria to produce the cel...Dear Editor,Life can utilize energy with high efficiency,especially with the help of aerobic respiration,where the tricarboxylic acid(TCA)cycle acts as an important metabolic engine for mitochondria to produce the cell energy currency of adenosine triphosphate(ATP),and nicotinamide adenine dinucleotide(NAD)plays a particular role of energy management molecule in the TCA cycle[1].展开更多
Obstacle avoidance is of great importance for mobile robots since it provides protection for the robots’safety and ensures their routine operations.Sensors are proven to play an important role in robots obstacle avoi...Obstacle avoidance is of great importance for mobile robots since it provides protection for the robots’safety and ensures their routine operations.Sensors are proven to play an important role in robots obstacle avoidance,and they are useful as well.However,more sensors indicating additional space,larger weight load and more energy consumption.Reducing unnecessary sensors is conducive to the development of mobile robots and remains promising.Here we demonstrate Sensor Free Obstacle-Passing Robots(SFOPRs)inspired by flies using the Obstacle-passing strategy instead of Obstacle avoidance.The ability to autonomously adjust its direction after hitting obstacles and the ability to continuously hit obstacles are 2 key problems that need to be solved to build this robot.Owing to arc-shaped head design and undulating motion behaviors,the robots can autonomously adjust their direction to the outline of obstacles,such as a 90°corner,dispersive irregular obstacles,and even an"S"type channel without the assistance of any sensor.Besides,the caterpillar-like movement enables robots to continuously hit obstacles.Furthermore,collaborative awareness and mutual aid can be realized among two or more prototype robots,indicating simple yet functional units for future swarm robots.This study could provide a new strategy to pursue sensor-free obstacle-passing robots for future swarm robot applications.展开更多
Strong light decreases the rate of photosynthesis and assimilates production of crop plants. Plants with different carbon reduction cycles respond differently to strong light stress. However, variation in photoinhibit...Strong light decreases the rate of photosynthesis and assimilates production of crop plants. Plants with different carbon reduction cycles respond differently to strong light stress. However, variation in photoinhibition in leaves with different photosynthetic characteristics in maize is not clear. In this experiment, we used the first leaves (with an incomplete C4 cycle) and fifth leaves (with a complete C4 cycle) of maize plants as well as the fifth leaves (C3 cycle) of tobacco plants as a reference to measure the photosynthetic rate (PN) and chlorophyll a parameters under strong light stress. During treatment, PN, the maximal fluorescence (Fm), the maximal quantum yield of PSII photochemistry (Fv/Fm), and the number of active photosystem II (PSII) reaction centers per excited cross-section (RC/CSm) declined dramatically in all three types of leaves but to different degrees. PN, Fm, Fv/Fm, and RC/CSm were less inhibited by strong light in C4 leaves. The results showed that maize C4 leaves with higher rates of photosynthesis are more tolerant to strong light stress than incomplete C4 leaves, and the carbon reduction cycle is more important to photoprotection in C4 leaves, while state transition is critical in incomplete C4 leaves.展开更多
Withering is a critical process to form the unique aroma of high-quality white tea.To study the mechanism underlying aroma changes during the white withering,we herein conducted volatile metabolomics and transcriptomi...Withering is a critical process to form the unique aroma of high-quality white tea.To study the mechanism underlying aroma changes during the white withering,we herein conducted volatile metabolomics and transcriptomics of the young leaves from the'Fuding Dahaocha'tea cultivar.As the withering time extended,the content of major aroma components increased significantly,score of sensory evaluation and Owuor's flavor index(OFI)also increased.The aromatic substances that accumulated during white tea withering were mainly volatile terpenes and esters.Their change trends were largely consistent with the gene expression of theα-linolenic acid metabolic pathways,while the correlation between the trends in volatiles and the gene expression of the terpenoid biosynthesis pathways was more complex and induced by the jasmonic acid(JA)signaling pathway.Additionally,we also explored the regulation pattern of key genes in the signaling pathway by related transcription factors.Three coexpression networks strongly correlated to the variation of volatile component content during withering were identified by weighted gene coexpression network analysis(WGCNA).Our results provide a new perspective on the processing mechanism and quality improvement of white tea.展开更多
The chemical weathering can consume atmosphere/soil CO2. Human activities such as pollution, fertilization and acid precipitation have exerted a large impact on CO2 intake by carbonate weathering. Thus, based on the a...The chemical weathering can consume atmosphere/soil CO2. Human activities such as pollution, fertilization and acid precipitation have exerted a large impact on CO2 intake by carbonate weathering. Thus, based on the analysis on chemical component change of the karst groundwater in the karst ridge watershed of Conglin Village, Fuling District of Chongqing City, the influence of human activities such as fertilization, sewage discharges from mustard tuber processing, breeding industry and acid rain precipitation on carbonate weathering and CO2 intake in 1980, 2003 and 2006 was studied. The results showed that CO2 intake by carbonate rock declined with year. Because H+ derived from acid sewage discharge, fertilization and acid precipitation reacted with carbonate rock when mustard tuber production and swine breeding were developed fleetly after 2000 as well as the burning amount of high-sulfur coal augmented persistently, which led to the increase of(Ca2++Mg2+)/HCO3-. The difference on charge between Ca2++Mg2+ and HCO3- was balanced by NO3-+SO42-. The control on pollution and acid rain, especially the pre-neutralization of acid waste water, would rejuvenate the atmospheric CO2 intake strength of carbonate weathering besides the protection of water and soil environment.展开更多
Grape crops are a great source of income for farmers.The yield and quality of grapes can be improved by preventing and treating diseases.The farmer’s yield will be dramatically impacted if diseases are found on grape...Grape crops are a great source of income for farmers.The yield and quality of grapes can be improved by preventing and treating diseases.The farmer’s yield will be dramatically impacted if diseases are found on grape leaves.Automatic detection can reduce the chances of leaf diseases affecting other healthy plants.Several studies have been conducted to detect grape leaf diseases,but most fail to engage with end users and integrate the model with real-time mobile applications.This study developed a mobile-based grape leaf disease detection(GLDD)application to identify infected leaves,Grape Guard,based on a TensorFlow Lite(TFLite)model generated from the You Only Look Once(YOLO)v8 model.A public grape leaf disease dataset containing four classes was used to train the model.The results of this study were relied on the YOLO architecture,specifically YOLOv5 and YOLOv8.After extensive experiments with different image sizes,YOLOv8 performed better than YOLOv5.YOLOv8 achieved 99.9%precision,100%recall,99.5%mean average precision(mAP),and 88%mAP50-95 for all classes to detect grape leaf diseases.The Grape Guard android mobile application can accurately detect the grape leaf disease by capturing images from grape vines.展开更多
As the highest and largest plateau in the world,the Qinghai-Tibet Plateau(QTP)covers wide geological,topographical and climatic gradients and thus acts as a major center for biodiversity and houses a diverse array of ...As the highest and largest plateau in the world,the Qinghai-Tibet Plateau(QTP)covers wide geological,topographical and climatic gradients and thus acts as a major center for biodiversity and houses a diverse array of high elevation ecosystems.Together these factors make the QTP a critical ecological shield for Asia.However,the composition,structure and function of plant diversity in QTP has experienced profound changes in recent decades.Long-term on-site monitoring,fieldexperiments,remote sensing,and simulations have led to significantadvances in our understanding of how plant diversity on the QTP has responded to climate change and human activity.This review synthesizes findingsfrom previous researches on how climate change and human activity have impacted plant diversity on the QTP.We identify gaps in our knowledge and highlight the need for interdisciplinary studies,long-term monitoring networks,and adaptive management strategies to enhance our knowledge and safeguard the QTP’s biodiversity amid accelerating global climate change.展开更多
Electromagnetic devices have been widely used in the fields of information communication,medical treatment,electrical engineering,and national defense,and their properties are strongly dependent on the constituent ele...Electromagnetic devices have been widely used in the fields of information communication,medical treatment,electrical engineering,and national defense,and their properties are strongly dependent on the constituent electromagnetic materials.Conversely,electromagnetic metamaterials(EMMs),which are artificially engineered with distinctive electromagnetic properties,can overcome the limitations of natural materials owing to their structural advantages.Three-dimensional(3D)printing is the most effec-tive technique for fabricating EMM devices with different geometric parameters and associated proper-ties.However,conventional 3D-printed EMM devices may lack manufacturing flexibility and environmental adaptability to different physical stimuli,such as electric and magnetic fields.Four-dimensional(4D)printing is an ideal technique for schemes to integrate structural design with intelligent materials environmentally adaptive to external fields,for example,the printed components can change shape under electric stimulation.Given the rapid advancements in the EMM field,this paper first reviews typical EMM devices,their design theories,and underlying principles.Subsequently,it presents various EMM structural topologies and manufacturing technologies,emphasizing the feasibility of combining 3D and 4D printing.In addition,we highlight the important applications of EMMs and their future trends and the challenges associated with functional EMMs and additive manufacturing.展开更多
Additive manufacturing(AM)technology has revolutionized engineering field by enabling the creation of intricate,high-performance structures that were once difficult or impossible to fabricate.This transformative techn...Additive manufacturing(AM)technology has revolutionized engineering field by enabling the creation of intricate,high-performance structures that were once difficult or impossible to fabricate.This transformative technology has particularly advanced the development of metamaterials-engineered materials whose unique properties arise from their structure rather than composition-unlocking immense potential in fields ranging from aerospace to biomedical engineering.展开更多
1.Introduction To design novel architectures with unique properties that surpass those of natural matter,scientists have developed diverse structures/materials by incorporating artificial structures of periodic/aperio...1.Introduction To design novel architectures with unique properties that surpass those of natural matter,scientists have developed diverse structures/materials by incorporating artificial structures of periodic/aperiodic nano-,micro-,and macro-scale,so called metamaterials.展开更多
An idea hits us that in-situ synthesizing ceramic phase at intergranular regions of RE-Fe-B alloys should be beneficial to the performance of the materials against corrosion,and in this work a new nanoscale(Zr,Ti)B_(2...An idea hits us that in-situ synthesizing ceramic phase at intergranular regions of RE-Fe-B alloys should be beneficial to the performance of the materials against corrosion,and in this work a new nanoscale(Zr,Ti)B_(2)with space and point groups of P6/mmm and Fmmm,respectively,was successfully synthesized in NdCeFeB sintered magnets.The hcp-structured(Zr,Ti)B_(2)phases are present in a stripe-like shape.Some of(Zr,Ti)B_(2)are developed at interfaces,and the others exist inside grain boundary phase.They coexist with REFe_(2)and RE-rich phases at intergranular regions.When proximity to RE2Fe14B grains,their orientation relationships obey[001]_(Nd_(2)Fe_(14)B)‖[110](Zr,Ti)B_(2).The formation of(Zr,Ti)B_(2)generates significant local compressive stress,being 8.48 GPa,and plenty of reliefs are developed inside the RE2Fe14B grains.The in-situ formed(Zr,Ti)B_(2)modifies the magnet microstructure,lessens the favorable sites for absorption reaction,narrows reaction channels,and reduces the potential difference between intergranular phase and main phase.Such favorable factors greatly enhance the corrosion resistance with an icorrdecrement by 70%in comparison to the unmodified magnet.These new discoveries are thought to be able to provide an insight into the method of potentially improving properties of magnets.展开更多
基金supported by Guangdong Major Project of Basic and Applied Basic Research, China (No. 2020B0301030006)Fundamental Research Funds for the Central Universities, China (No. SWU-XDJH202313)+1 种基金Chongqing Postdoctoral Science Foundation Funded Project, China (No. 2112012728014435)the Chongqing Postgraduate Research and Innovation Project, China (No. CYS23197)。
文摘A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface,which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate.The results show that cold-pressing produces intense plastic deformation near the corrugated surface of the Al plate,which promotes dynamic recrystallization of the Al substrate near the interface during the subsequent hot-pressing.In addition,the initial corrugation on the surface of the Al plate also changes the local stress state near the interface during hot pressing,which has a large effect on the texture components of the substrates near the corrugated interface.The construction of the corrugated interface can greatly enhance the shear strength by 2−4 times due to the increased contact area and the strong“mechanical gearing”effect.Moreover,the mechanical properties are largely depended on the orientation relationship between corrugated direction and loading direction.
基金supported by the National Natural Science Foundation of China(No.22431004)Fund of Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates(No.2023B1212060003)。
文摘Aggregation-induced emission(AIE)polymers have been extensively studied;however,the integration of AIE units into polyelectrolytes remains largely limited by the laborious multistep synthesis of pre-designed emissive monomers.Herein,we report a one-pot multicomponent polymerization method that directly produces main-chain charged polyelectrolytes with intrinsic AIE characteristics from non-emissive building blocks.By optimizing the monomer structures and reaction conditions,a series of soluble high-molecular-weight polymers with welldefined backbones were obtained in high yields.The resulting polyelectrolytes displayed robust AIE behavior,exhibiting fluorescence enhancement up to about 60-fold in an aqueous environment,and maintained excellent thermal stability.Owing to their cationic backbones,these polymers interact strongly with microbial surfaces and exhibit remarkable antimicrobial activities.This study establishes a synthetically efficient route to AIE polyelectrolytes and highlights their potential applications as multifunctional materials for bioimaging,antimicrobial therapy,and other applications.
基金supported by Guangdong Major Project of Basic and Applied Basic Research,No. 2020B0301030006。
文摘Laminated metal composites(LMCs) are a unique composite material and have great application prospects in automobiles, ships, aircraft,and other manufacturing industries. As lightweight materials, the Mg/Al LMCs are expected to combine the advantages of both Mg and Al alloys to broaden their application prospects. Roll-bonding is the most popular process for the fabrication of Mg/Al LMCs due to high production efficiency and good product quality stability. The roll-bonding process involves the deformation of the substrates and the formation of the interfacial diffusion layer. The latter will directly determine the interface bonding strength of Mg/Al LMCs. Bonding strength is very sensitive to the thickness of the reaction layer in the diffusion layer. When the thickness of the reaction layer exceeds 5 μm, the bonding strength decreases sharply. Therefore, controlling the thickness of the reaction layer is very important for the design of rolling parameters.The latest research also showed that the addition of intermediate layer metal and the construction of three-dimensional interfaces can further improve the interface bonding strength. How to apply these methods to roll-bonding is the focus of future research. Recently, a new rolling technique, corrugated roll/plat roll rolling+flat roll/flat roll rolling has been developed to fabricate Mg/Al LMCs. It can effectively promote the deformation of the hard layer and generate a wavy interface, resulting in the enhancement of the bonding quality and rolling quality.In the current review, the effects of rolling parameters and subsequent annealing on the interface structure of Mg/Al LMCs were elaborated in detail. The application of some special rolling techniques in the preparation of Mg/Al LMCs was also summarized. The latest research results on the relationship between interface structure and mechanical properties of Mg/Al LMCs were reviewed. Finally, further research directions in this field were proposed.
基金financially supported by the National Natural Science Foundation of China(No. 51674035)
文摘Using boron powder as additive, the preparation of zirconium diboride(ZrB 2) by carbothermal reduction was investigated. The results show that the carbothermal reduction cannot be completely done until the temperature is more than 1900 ℃. The ZrB2 particles prepared without boron(B) additive at 1900 ℃ for 3 h are rodlike and show a preferential grain growth along [001] direction. B additive changes the heat effect of the raw materials. With B additive, the morphology of ZrB2 particles turns to be regular shape. The average particle size is about 3.6 μm with 2.5 wt% B additives. With more B additive, the shape of particles turns to be round like and the average particle size is decreased to 2.3 μm when 5 wt% B is added. The existence of oxides in grain boundary is a key factor to keep ZrB2 ceramic from deep densification. Using ZrB2 powder prepared with 5 wt% B additives, by controlling carbon content in ZrB2 powder, ZrB2 ceramic with 93%relative density is hot-pressed.
基金funded by the South Carolina Natural Resources Conservation Service(SC NRCS)with grant number 2021917
文摘Background: Carbon sequestration through recommended forest management practices is an ecosystem service that helps mitigate climate change and its impacts while generating carbon credits for forestland owners to sell in cap-and-trade programs. The California’s cap-and-trade program (California’s carbon market hereafter) allows forestland owners from any part of the contiguous United States to supply carbon credits to compliance entities. In this study, we estimate South Carolina (SC) private forestland owners’willingness to accept compensations to participate in the California’s carbon market using a contingent valuation method. Results: We estimate forestland owners’mean willingness to accept as$67 per acre per year. Our results reveal higher probability of participation of forestland owners with interests in preserving forest ecosystems than those who do not. Additionally, forestland owners who trust in information about climate change from scientists or government are willing to participate more than those who do not. Conclusions: Various factors hinder landowners’ability to participate in carbon markets. Forestland owners in SC consider legislative uncertainty and long-time commitment as the main barriers to participation in California’s carbon market. From this research, average forestland tenure in SC is 27 years, which is far less than the 100-year time commitment of the California’s carbon market. Of those who agreed to participate, choosing between adopting and not adopting any of the three main forest management practices in the California’s carbon market:28% are likely to adopt improved forest management (IFM) practices, 24% are likely to adopt reforestation due to understocked forestlands, and 14% are likely to adopt avoided conversion. In another development, the concept of aggregation has dominated discussions in the California’s carbon market of late. It is an advocacy to include small-scale forestlands in the California’s carbon market. To aggregate, different forestland owners will combine their forestlands to participate. We find that 79% of SC forestland owners are willing to aggregate to participate. However, this research is unable to determine how much total forestland is available in SC for carbon market. We recommend future research in the State on forestland owners’participation in carbon market should consider evaluating forestland availability.
基金financially supported by the Science and Technology Program of University of Jinan(Nos.XKY2103,XKY2105)National Natural Science Foundation of China(Nos.51902130,52072085)Key Research and Development project of Shandong Province(No.2019GGX102087)。
文摘Low-cost and efficient oxygen reduction reaction(ORR)electrocatalysts are the key to developing Zn-air batteries for renewable energy storage.Herein,the Mn-N-P doped carbon sphere was prepared through polymerization of hexachlorotripolyphosphazene(HCCP)and phloroglucinol,and then followed the calcination at 900°C.Theory calculations demonstrated the introduction of Mn in N-P doped carbon could lower the dissociation barrier of O2into O*and promote the ORR through a 4e-pathway.The asprepared catalysts exhibited a half-wave potential of 0.82 V vs.RHE and limiting current density of 5.2 m A/cm^(2)toward ORR,which was comparable to those of the commercial Pt/C catalysts.In addition,Zn-air batteries with 0.05 Mn-N-P-C catalysts showed a high specific capacity of 830 m Ah/gZnand excellent cycle stability.This facile approach demonstrated herein could be a solution to develop optimum non-precious metal catalysts for the application in cathodes of proton exchange membrane fuel cells.This study also provides new insight to design the catalysts of multi-heteroatom coordinated metal in the carbon matrix for both fundamental researches and practical applications.
基金supported by the National Key R&D Program of China(2021YFA1200404 and 2018YFE0205501)the National Natural Science Foundation of China(T224100002).
文摘Dear Editor,Life can utilize energy with high efficiency,especially with the help of aerobic respiration,where the tricarboxylic acid(TCA)cycle acts as an important metabolic engine for mitochondria to produce the cell energy currency of adenosine triphosphate(ATP),and nicotinamide adenine dinucleotide(NAD)plays a particular role of energy management molecule in the TCA cycle[1].
基金supported by the Academic frontier youth team(2017QYTD06,2018QYTD04)at Huazhong University of Science and Technology(HUST)the National 1000 Young Talents Program of China,and the initiatory financial support was from HUST.
文摘Obstacle avoidance is of great importance for mobile robots since it provides protection for the robots’safety and ensures their routine operations.Sensors are proven to play an important role in robots obstacle avoidance,and they are useful as well.However,more sensors indicating additional space,larger weight load and more energy consumption.Reducing unnecessary sensors is conducive to the development of mobile robots and remains promising.Here we demonstrate Sensor Free Obstacle-Passing Robots(SFOPRs)inspired by flies using the Obstacle-passing strategy instead of Obstacle avoidance.The ability to autonomously adjust its direction after hitting obstacles and the ability to continuously hit obstacles are 2 key problems that need to be solved to build this robot.Owing to arc-shaped head design and undulating motion behaviors,the robots can autonomously adjust their direction to the outline of obstacles,such as a 90°corner,dispersive irregular obstacles,and even an"S"type channel without the assistance of any sensor.Besides,the caterpillar-like movement enables robots to continuously hit obstacles.Furthermore,collaborative awareness and mutual aid can be realized among two or more prototype robots,indicating simple yet functional units for future swarm robots.This study could provide a new strategy to pursue sensor-free obstacle-passing robots for future swarm robot applications.
文摘Strong light decreases the rate of photosynthesis and assimilates production of crop plants. Plants with different carbon reduction cycles respond differently to strong light stress. However, variation in photoinhibition in leaves with different photosynthetic characteristics in maize is not clear. In this experiment, we used the first leaves (with an incomplete C4 cycle) and fifth leaves (with a complete C4 cycle) of maize plants as well as the fifth leaves (C3 cycle) of tobacco plants as a reference to measure the photosynthetic rate (PN) and chlorophyll a parameters under strong light stress. During treatment, PN, the maximal fluorescence (Fm), the maximal quantum yield of PSII photochemistry (Fv/Fm), and the number of active photosystem II (PSII) reaction centers per excited cross-section (RC/CSm) declined dramatically in all three types of leaves but to different degrees. PN, Fm, Fv/Fm, and RC/CSm were less inhibited by strong light in C4 leaves. The results showed that maize C4 leaves with higher rates of photosynthesis are more tolerant to strong light stress than incomplete C4 leaves, and the carbon reduction cycle is more important to photoprotection in C4 leaves, while state transition is critical in incomplete C4 leaves.
基金funded by the Fujian Agriculture and Forestry University Construction Project for Technological Innovation and Service System of Tea Industry Chain,grant number K1520005A and KH220095A.
文摘Withering is a critical process to form the unique aroma of high-quality white tea.To study the mechanism underlying aroma changes during the white withering,we herein conducted volatile metabolomics and transcriptomics of the young leaves from the'Fuding Dahaocha'tea cultivar.As the withering time extended,the content of major aroma components increased significantly,score of sensory evaluation and Owuor's flavor index(OFI)also increased.The aromatic substances that accumulated during white tea withering were mainly volatile terpenes and esters.Their change trends were largely consistent with the gene expression of theα-linolenic acid metabolic pathways,while the correlation between the trends in volatiles and the gene expression of the terpenoid biosynthesis pathways was more complex and induced by the jasmonic acid(JA)signaling pathway.Additionally,we also explored the regulation pattern of key genes in the signaling pathway by related transcription factors.Three coexpression networks strongly correlated to the variation of volatile component content during withering were identified by weighted gene coexpression network analysis(WGCNA).Our results provide a new perspective on the processing mechanism and quality improvement of white tea.
文摘The chemical weathering can consume atmosphere/soil CO2. Human activities such as pollution, fertilization and acid precipitation have exerted a large impact on CO2 intake by carbonate weathering. Thus, based on the analysis on chemical component change of the karst groundwater in the karst ridge watershed of Conglin Village, Fuling District of Chongqing City, the influence of human activities such as fertilization, sewage discharges from mustard tuber processing, breeding industry and acid rain precipitation on carbonate weathering and CO2 intake in 1980, 2003 and 2006 was studied. The results showed that CO2 intake by carbonate rock declined with year. Because H+ derived from acid sewage discharge, fertilization and acid precipitation reacted with carbonate rock when mustard tuber production and swine breeding were developed fleetly after 2000 as well as the burning amount of high-sulfur coal augmented persistently, which led to the increase of(Ca2++Mg2+)/HCO3-. The difference on charge between Ca2++Mg2+ and HCO3- was balanced by NO3-+SO42-. The control on pollution and acid rain, especially the pre-neutralization of acid waste water, would rejuvenate the atmospheric CO2 intake strength of carbonate weathering besides the protection of water and soil environment.
文摘Grape crops are a great source of income for farmers.The yield and quality of grapes can be improved by preventing and treating diseases.The farmer’s yield will be dramatically impacted if diseases are found on grape leaves.Automatic detection can reduce the chances of leaf diseases affecting other healthy plants.Several studies have been conducted to detect grape leaf diseases,but most fail to engage with end users and integrate the model with real-time mobile applications.This study developed a mobile-based grape leaf disease detection(GLDD)application to identify infected leaves,Grape Guard,based on a TensorFlow Lite(TFLite)model generated from the You Only Look Once(YOLO)v8 model.A public grape leaf disease dataset containing four classes was used to train the model.The results of this study were relied on the YOLO architecture,specifically YOLOv5 and YOLOv8.After extensive experiments with different image sizes,YOLOv8 performed better than YOLOv5.YOLOv8 achieved 99.9%precision,100%recall,99.5%mean average precision(mAP),and 88%mAP50-95 for all classes to detect grape leaf diseases.The Grape Guard android mobile application can accurately detect the grape leaf disease by capturing images from grape vines.
基金the Second Tibetan Plateau Scientific Expedition and Research program(2024QZKK0200)the Key Projects of the Joint Fund of the National Natural Science Foundation of China(U23A20149)+2 种基金Yunnan Key R&D Program(202403AC00028)for supporting the fieldexcursion,samples collections and ecological experiment in QTP.Rest co-authors acknowledge the Yunnan Innovation Team Project(202305AS350004 to Yang Yang)the Young Academic and Technical Leader Raising Foundation of Yunnan Province(202205AC160053 to Jianguo Chen)the CAS“Light of West China”Program(xbzg-zdsys-202319 to Bo Song),Yunnan Revitalization Talent Support Program“Young Talent”Project(to Yazhou Zhang),National Youth Talent Support Program(to Yang Niu)and Postdoctoral(oversea)Fund of Ministry of Education of China(to Zihan Jiang)。
文摘As the highest and largest plateau in the world,the Qinghai-Tibet Plateau(QTP)covers wide geological,topographical and climatic gradients and thus acts as a major center for biodiversity and houses a diverse array of high elevation ecosystems.Together these factors make the QTP a critical ecological shield for Asia.However,the composition,structure and function of plant diversity in QTP has experienced profound changes in recent decades.Long-term on-site monitoring,fieldexperiments,remote sensing,and simulations have led to significantadvances in our understanding of how plant diversity on the QTP has responded to climate change and human activity.This review synthesizes findingsfrom previous researches on how climate change and human activity have impacted plant diversity on the QTP.We identify gaps in our knowledge and highlight the need for interdisciplinary studies,long-term monitoring networks,and adaptive management strategies to enhance our knowledge and safeguard the QTP’s biodiversity amid accelerating global climate change.
基金sponsored by the National Natural Science Foundation of China(52275331 and 52205358)the National Key Research and Development Program of China(2023YFB4604800)+1 种基金the Key Research and Development Program of Hubei Province(2022BAA011)the Hong Kong Scholars Program(XJ2022014).
文摘Electromagnetic devices have been widely used in the fields of information communication,medical treatment,electrical engineering,and national defense,and their properties are strongly dependent on the constituent electromagnetic materials.Conversely,electromagnetic metamaterials(EMMs),which are artificially engineered with distinctive electromagnetic properties,can overcome the limitations of natural materials owing to their structural advantages.Three-dimensional(3D)printing is the most effec-tive technique for fabricating EMM devices with different geometric parameters and associated proper-ties.However,conventional 3D-printed EMM devices may lack manufacturing flexibility and environmental adaptability to different physical stimuli,such as electric and magnetic fields.Four-dimensional(4D)printing is an ideal technique for schemes to integrate structural design with intelligent materials environmentally adaptive to external fields,for example,the printed components can change shape under electric stimulation.Given the rapid advancements in the EMM field,this paper first reviews typical EMM devices,their design theories,and underlying principles.Subsequently,it presents various EMM structural topologies and manufacturing technologies,emphasizing the feasibility of combining 3D and 4D printing.In addition,we highlight the important applications of EMMs and their future trends and the challenges associated with functional EMMs and additive manufacturing.
文摘Additive manufacturing(AM)technology has revolutionized engineering field by enabling the creation of intricate,high-performance structures that were once difficult or impossible to fabricate.This transformative technology has particularly advanced the development of metamaterials-engineered materials whose unique properties arise from their structure rather than composition-unlocking immense potential in fields ranging from aerospace to biomedical engineering.
基金financially supported by the National Key Research and Development Program of China(2023YFB4604800)the National Natural Science Foundation of China(52275331)financial support from the Hong Kong Scholars Program(XJ2022014)。
文摘1.Introduction To design novel architectures with unique properties that surpass those of natural matter,scientists have developed diverse structures/materials by incorporating artificial structures of periodic/aperiodic nano-,micro-,and macro-scale,so called metamaterials.
基金Project supported by the National Natural Science Foundation of China(52174346)Natural Science Foundation of Shandong Province(ZR2021ME031,ZR2022QE115)Innovation Capability Enhancement Project for Technology Oriented Small and Medium Sized Enterprises of Shandong Province(2022TSGC2586)。
文摘An idea hits us that in-situ synthesizing ceramic phase at intergranular regions of RE-Fe-B alloys should be beneficial to the performance of the materials against corrosion,and in this work a new nanoscale(Zr,Ti)B_(2)with space and point groups of P6/mmm and Fmmm,respectively,was successfully synthesized in NdCeFeB sintered magnets.The hcp-structured(Zr,Ti)B_(2)phases are present in a stripe-like shape.Some of(Zr,Ti)B_(2)are developed at interfaces,and the others exist inside grain boundary phase.They coexist with REFe_(2)and RE-rich phases at intergranular regions.When proximity to RE2Fe14B grains,their orientation relationships obey[001]_(Nd_(2)Fe_(14)B)‖[110](Zr,Ti)B_(2).The formation of(Zr,Ti)B_(2)generates significant local compressive stress,being 8.48 GPa,and plenty of reliefs are developed inside the RE2Fe14B grains.The in-situ formed(Zr,Ti)B_(2)modifies the magnet microstructure,lessens the favorable sites for absorption reaction,narrows reaction channels,and reduces the potential difference between intergranular phase and main phase.Such favorable factors greatly enhance the corrosion resistance with an icorrdecrement by 70%in comparison to the unmodified magnet.These new discoveries are thought to be able to provide an insight into the method of potentially improving properties of magnets.
