A new organocatalytic double annulation cascade involving scission/recombination of N-O bonds of nitrones is reported for the first time, and used to produce a range of hitherto unprecedented tricyclic bridged-fused b...A new organocatalytic double annulation cascade involving scission/recombination of N-O bonds of nitrones is reported for the first time, and used to produce a range of hitherto unprecedented tricyclic bridged-fused benzo[d]azepines bearing three stereogenic centers with moderate to good yields and complete diastereoselectivity. A quinine-catalyzed reaction of yne–allenone esters with nitrones worked well and provided a convergent and regioselective pathway to access these three-dimensional scaffolds from the planar conjugated system. Density functional theory(DFT) calculations have been applied to understand the key process for forming diradical intermediates.展开更多
Identification of variables that influence differences between predicted and observed cycling times for one cyclist commuting to Okanagan College (OC) was performed using principal components analysis. These data were...Identification of variables that influence differences between predicted and observed cycling times for one cyclist commuting to Okanagan College (OC) was performed using principal components analysis. These data were used to create a personalized predictive time algorithm, which was subsequently applied in an isochrone map format centered on OC. A 29% difference in the area within the 20-minute commuting time was estimated, suggesting that potential residential location choices made with inaccurate isochrone maps are inaccurate. A comparison with an isochron cycling map for Trinity College Dublin was made to emphasise differences in the impact/implications of this type of map in the promotion of sustainable transportation for a post-secondary institution. It is determined that these maps may misinform new community members as to areas of residential location choice.展开更多
To investigate the distribution characteristics and influencing factors of bicycle detour behavior,this study ac-curately identified detour behavior using global positioning system(GPS)track data from shared bicycles....To investigate the distribution characteristics and influencing factors of bicycle detour behavior,this study ac-curately identified detour behavior using global positioning system(GPS)track data from shared bicycles.Factors such as travel time,road conditions,public transportation facilities,and land use types were considered in constructing a detour behavior influence model based on the CatBoost machine learning algorithm.The interpretability of the machine learning framework was enhanced via Shapley additive explanations(SHAP),enabling an analysis of the impact of each factor on detour behavior.The results indicated that the CatBoost model effectively recognized detour behavior with high accuracy.The frequency of detour behavior increased with higher road levels,greater distances to crossing facilities,wider bike lanes,and an increased number of bus stops,subway stations,and leisure and entertainment facilities,while it decreased with a higher number of office commuting facilities.In addition,detour behavior was more prevalent on weekends,during off-peak hours,and under conditions involving physical central lane separation and physical bike lane separation.These findings offer a novel approach for identifying bicycle riding behaviors and analyzing their influencing factors,providing effective technical support for non-motorized traffic management and infrastructure optimization.展开更多
Two environmentalists using bamboo bicycles to promote green transportation.THE exhaust emissions generated by transporting the world’s population on a daily basis are one of the main sources of greenhouse gases.Vehi...Two environmentalists using bamboo bicycles to promote green transportation.THE exhaust emissions generated by transporting the world’s population on a daily basis are one of the main sources of greenhouse gases.Vehicles such as cars,subways,and motorcycles,all produce carbon emissions.展开更多
CHINA.Bicycle Output.China’s bicycle production saw solid growth last year,increasing by 0.4 percent year on year to reach 99.54 million units,said Zheng Xiaoling,spokesperson for the China Bicycle Association.
Designed and built by eight Dutch engineers,the worlds longest bicycle is 55.16 meters,roughly the same length as four double-decker buses.39-year-old Ivan Schalk had been thinking about building the world's longe...Designed and built by eight Dutch engineers,the worlds longest bicycle is 55.16 meters,roughly the same length as four double-decker buses.39-year-old Ivan Schalk had been thinking about building the world's longest bicycle since reading about it in The Guinness Book of Records when he was a child,but he only started this project in 2018,as a way to fill up his free time.展开更多
Chiral aryl cyclohex-3-en ether scaffold is widely present in bioactive natural products and drugs.The exploitation of efficient and enantioselective methods for the construction of aryl cyclohex-3-en ether scaffold i...Chiral aryl cyclohex-3-en ether scaffold is widely present in bioactive natural products and drugs.The exploitation of efficient and enantioselective methods for the construction of aryl cyclohex-3-en ether scaffold is significant.Herein we disclose a chiral N,N’-dioxide/Lewis acid complex-catalyzed asymmetric inverse-electron-demand Diels-Alder(IEDDA)reaction using electron-deficient 3-carboalkoxyl-2-pyrones and less electron-enriched aryl enol ethers as reactants.A wide range of non-and 1,2-disubstituted acyclic aryl enol ethers are applicable to deliver diverse chiral bridged bicyclic lactones in high yields and stereoselectivities(up to 96%yield,>20:1 dr,97:3 er).The bridged bicyclic lactone core can be easily converted into chiral aryl cyclohex-3-en ether scaffold.Notably,DFT calculations revealed a stepwise and endo mechanism to explain the high enantioselectivity controlled by the cooperative effect of the steric factors and the dispersion interactions between ligands and enol ethers.展开更多
Wearing helmetswhile riding electric bicycles can significantly reduce head injuries resulting fromtraffic accidents.To effectively monitor compliance,the utilization of target detection algorithms through traffic cam...Wearing helmetswhile riding electric bicycles can significantly reduce head injuries resulting fromtraffic accidents.To effectively monitor compliance,the utilization of target detection algorithms through traffic cameras plays a vital role in identifying helmet usage by electric bicycle riders and recognizing license plates on electric bicycles.However,manual enforcement by traffic police is time-consuming and labor-intensive.Traditional methods face challenges in accurately identifying small targets such as helmets and license plates using deep learning techniques.This paper proposes an enhanced model for detecting helmets and license plates on electric bicycles,addressing these challenges.The proposedmodel improves uponYOLOv8n by deepening the network structure,incorporating weighted connections,and introducing lightweight convolutional modules.These modifications aim to enhance the precision of small target recognition while reducing the model’s parameters,making it suitable for deployment on low-performance devices in real traffic scenarios.Experimental results demonstrate that the model achieves an mAP@0.5 of 91.8%,showing an 11.5%improvement over the baselinemodel,with a 16.2%reduction in parameters.Additionally,themodel achieves a frames per second(FPS)rate of 58,meeting the accuracy and speed requirements for detection in actual traffic scenarios.展开更多
In this study,a detailed analysis of the combustion behaviors of the lithium iron phosphate(LFP)and lithium manganese oxide(LMO)batteries used in electric bicycles was conducted.This research included quantitative mea...In this study,a detailed analysis of the combustion behaviors of the lithium iron phosphate(LFP)and lithium manganese oxide(LMO)batteries used in electric bicycles was conducted.This research included quantitative measurements of the combustion duration,flame height,combustion temperature,heat release rate,and total heat release.The results indicated that LMO batteries exhibited higher combustion temperatures of 600–700°C,flame heights of 70–75 cm,a significantly higher heat release rate of40.1 k W(12 Ah),and a total heat release of 1.04 MJ(12 Ah)compared to LFP batteries with the same capacity.Based on these experimental results,a normalized total heat release(NORTHR)parameter was proposed,demonstrating good universality for batteries with different capacities.Utilizing this parameter,quantitative calculations and optimization of the extinguishing agent dosage were conducted for fires involving these two types of batteries,and the method was validated by extinguishing fires for these two types of battery packs with water-based extinguishing fluids.展开更多
Four pillar[5]arene-based bicyclic compounds,so-called molecular universal joint(MUJ),were synthesized by incorporating a bisamide ring containing N,O,or S-heteroatom groups,which served as stimuli-responsive chiropti...Four pillar[5]arene-based bicyclic compounds,so-called molecular universal joint(MUJ),were synthesized by incorporating a bisamide ring containing N,O,or S-heteroatom groups,which served as stimuli-responsive chiroptical molecular devices.The structure of MUJ was confirmed by 1H NMR spectra and single-crystal X-ray diffraction analysis,and their planar-chiral enantiomers were successfully separated.Chiroptical inversion behaviors from in to out configurations triggered by temperature,solvent,and vip complexation were investigated by circular dichroism spectra.Chiroptical inversion could be realized in the presence of adiponitrile in certain solvents due to the solvation effects on the side ring and the threading of the vip into the pillar[5]arene cavity.However,the stronger self-included interactions between the cavity and the inside ring of certain MUJs led to inhibition of the switching.展开更多
M-xylene bicyclic peroxy radical(M-BPR)is an important atmospheric intermediate formed by the oxidation of m-xylene,which plays an important role in the new particle formation and growth of secondary organic aerosol.I...M-xylene bicyclic peroxy radical(M-BPR)is an important atmospheric intermediate formed by the oxidation of m-xylene,which plays an important role in the new particle formation and growth of secondary organic aerosol.In this work,the reaction mechanism,thermodynamic analysis,and kinetics of the reaction between M-BPR and HO_(2)were investigated at the CCSD(T)/cc-pVDZ//B3LYP/6-311G(d,p)level of theory coupled with transition state theory.The calculated results indicate that the title reaction can occur on both singlet and triplet potential energy surfaces,and the formation of hydroperoxides and 3O_(2)via triplet state is the main reaction channel,while the other four singlet product channels are negligible due to the higher barrier heights.Additionally,the reaction rate constants are estimated by using the transition state theory over the temperature range of 258 K to 378 K,and reaction rate constants arc found to be negatively correlated with temperature.At 298 K,the total rate constant for the title reaction is 1.86×10^(-11)cm^(3)·molecule^(-1)·s^(-1).The calculated rate constants over the studied temperature range were used to fit the data and the three-parameter Arrhenius ex-studied is obtainted to be k(T)=4.22×10^(-15)·(T/300)^(1.44)·exp(2505/T).展开更多
Objectives: The primary objective was to characterize the range of Knowledge, Attitude, and Practice (KAP) of Helmet use in children amongst parents to prevent head injuries and death. Methods: This is a cross-section...Objectives: The primary objective was to characterize the range of Knowledge, Attitude, and Practice (KAP) of Helmet use in children amongst parents to prevent head injuries and death. Methods: This is a cross-sectional study, done by online survey using a snowball sampling technique, the number of included responses were 386 parents (Male and female) living in Riyadh Aged 21 - 60 years old or above. Results: The study showed that there is a difference in Parents’ belief in the importance of helmet use while riding a Bicycle vs Motorcycle/Quad bike and that was affected by parents’ education level, almost all the people who answered the survey (76.7%) agree that it is important for their children to wear a helmet when riding both a Bicycle and a Motorcycle or Quadbike with a cumulative percentage of (93.8%). And almost all agreed on multiple approaches to help increase helmet use be it by forcing rental shops to give out helmets, forcing sellers to recommend the use of helmets, increasing awareness campaigns, and imposing fines for not wearing helmets. Conclusions: This study is the first to explore Family helmet use while riding Bicycles and Motorcycles/Quad bikes. Although Parent’s belief in the importance of helmet use for their children was high, it is clear that the level of practice is low. With that the risk of head injuries might be high, our findings suggest that safety interventions for increasing pediatric helmet use are needed to increase helmet use and reduce the risk of head injury and hospitalization.展开更多
In recent years,disorderly parking and difficult charging of electric bicycles have been challenges in urban management.The rapid growth of electric bicycles is in contradiction with the lack of dedicated parking spac...In recent years,disorderly parking and difficult charging of electric bicycles have been challenges in urban management.The rapid growth of electric bicycles is in contradiction with the lack of dedicated parking spaces and charging service facilities in towns and villages.To solve the issue of parking and charging electric bicycles in limited urban and rural spaces,prefabricated building technology is applied to the design of a multi-story electric bicycle parking lot.The multi-story prefabricated electric bicycle parking lot is utilized in urban and rural planning and design to upgrade parking facilities in old urban areas,land-constrained commercial areas,as well as counties,towns,and rural areas with inadequate municipal facilities.Multi-story prefabricated electric bicycle parking lots are the application exploration of industrial buildings,and promote the high-quality development planning and construction of towns and counties and villages.Compared with the single-story metal charging station,the multi-story assembled electric bicycle parking lot has the characteristics of integrating parking and charging,being more durable and safer in structure,accommodating a large number of vehicles,and improving the space utilization rate.展开更多
The system of public bicycles in the world known as"Bicycle sharing",is a service in which bicycles are made available for shared use to individuals with or without a certain fee.Users can take and return th...The system of public bicycles in the world known as"Bicycle sharing",is a service in which bicycles are made available for shared use to individuals with or without a certain fee.Users can take and return the bike at numerous locations in the urban parts of the city.As part of the CIVITAS ELAN project(2008-2012),which was aimed at improving the quality of life of citizens by establishing high-quality solutions in city traffic and to promote and encourage sustainable,clean and energy-efficient modes of traffic,a pilot project of student public bicycle(Studocikl)was implemented at the University of Zagreb.In the first phase the pilot project included the Faculty of Transport and Traffic Sciences(FTTS)where is currently implemented.In the second phase the project is planned to include the remaining faculties located at the Borongaj Campus.The idea behind the Studocikl project is to connect two remote locations of FTTS,between headquarters in Vukelićeva Street and Borongaj Campus.Registration(login,logout)of users and the entire administration is done through a web portal.Time of using bicycles is in the period from 8 am to 8 pm(working hours of FTTS).Studocikl was officially put into operation on the 17 September 2012 and in this paper will analyse its one-year operation.The paper will also make proposals for further Studocikl development in terms of:installing GPS trackers for satellite bicycle tracking,the application for smartphones,full automation of the registration,and explore the possibility of extending such service and modes of transportation at all faculties in the University of Zagreb.展开更多
Drawing upon Donna Haraway’s cyborg theory,this paper argues that the bicycle can be conceived as a cyborg extension of body and identity which transcended its mechanical essence to become an integral co-partner for ...Drawing upon Donna Haraway’s cyborg theory,this paper argues that the bicycle can be conceived as a cyborg extension of body and identity which transcended its mechanical essence to become an integral co-partner for women involved in resistance activities in WWII.More specifically,the study explores how women used cycling during World War Ⅱ not only for mobility but as a profound expression of courage,endurance and solidarity which enabled them to overcome physical and symbolic barriers under totalitarian regimes.The bicycle emerges not only as a central co-agent but also actively co-creates the situations in which it emerges as a transformative force.Cycling acted as a catalyst for personal and collective empowerment,fostering new subjectivities while transcending physical and social limitations.This study sparks multidimensional discourse on how technological tools can co-create our societies and identities,offering insights into how bicycles can drive socio-political change,promote emancipation and foster inclusivity.展开更多
Aim To develop a concise method for the synthesis of bicyclic azasugar and thiosugar with novel scaffold. Methods The two primary hydroxyl groups of compound 1 were selectively protected with tosyl cloloride in pyridi...Aim To develop a concise method for the synthesis of bicyclic azasugar and thiosugar with novel scaffold. Methods The two primary hydroxyl groups of compound 1 were selectively protected with tosyl cloloride in pyridine, followed by ring-closure with sodium sulfide or primary amine to form the oxy-bridged bicyclic molecules in good yields. Results Two bicyclic azasugars and a thiosugar were produced from L-sorbose in several steps. Conclusion The described procedures provide an efficient method to synthesize bicyclic azasugar and thiosugar with novel scaffold as potential glycosidase inhibitors.展开更多
The bicyclic product containing a chromene skeleton and a propargylamine skeleton（C（22）H（22）N2O2） was synthesized from the double sites of terminal alkyne, piperazine derivative and formaldehyde via one-pot proc...The bicyclic product containing a chromene skeleton and a propargylamine skeleton（C（22）H（22）N2O2） was synthesized from the double sites of terminal alkyne, piperazine derivative and formaldehyde via one-pot procedure. Its structure was characterized by ^1H NMR, ^13C NMR, IR and H RMS, and further confirmed by single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group P21/n with a = 12.6571（14）, b = 11.3249（12）, c = 12.6571（14） A, β = 105.22°,V = 1750.6（3） A^3, Z = 4, R = 0.0568 and w R = 0.1444. The fluorescence of the product was discussed.展开更多
基金financial support from the National Natural Science Foundation of China (Nos. 21871112 and 21971090)。
文摘A new organocatalytic double annulation cascade involving scission/recombination of N-O bonds of nitrones is reported for the first time, and used to produce a range of hitherto unprecedented tricyclic bridged-fused benzo[d]azepines bearing three stereogenic centers with moderate to good yields and complete diastereoselectivity. A quinine-catalyzed reaction of yne–allenone esters with nitrones worked well and provided a convergent and regioselective pathway to access these three-dimensional scaffolds from the planar conjugated system. Density functional theory(DFT) calculations have been applied to understand the key process for forming diradical intermediates.
文摘Identification of variables that influence differences between predicted and observed cycling times for one cyclist commuting to Okanagan College (OC) was performed using principal components analysis. These data were used to create a personalized predictive time algorithm, which was subsequently applied in an isochrone map format centered on OC. A 29% difference in the area within the 20-minute commuting time was estimated, suggesting that potential residential location choices made with inaccurate isochrone maps are inaccurate. A comparison with an isochron cycling map for Trinity College Dublin was made to emphasise differences in the impact/implications of this type of map in the promotion of sustainable transportation for a post-secondary institution. It is determined that these maps may misinform new community members as to areas of residential location choice.
基金The National Natural Science Foundation of China(No.52072012)。
文摘To investigate the distribution characteristics and influencing factors of bicycle detour behavior,this study ac-curately identified detour behavior using global positioning system(GPS)track data from shared bicycles.Factors such as travel time,road conditions,public transportation facilities,and land use types were considered in constructing a detour behavior influence model based on the CatBoost machine learning algorithm.The interpretability of the machine learning framework was enhanced via Shapley additive explanations(SHAP),enabling an analysis of the impact of each factor on detour behavior.The results indicated that the CatBoost model effectively recognized detour behavior with high accuracy.The frequency of detour behavior increased with higher road levels,greater distances to crossing facilities,wider bike lanes,and an increased number of bus stops,subway stations,and leisure and entertainment facilities,while it decreased with a higher number of office commuting facilities.In addition,detour behavior was more prevalent on weekends,during off-peak hours,and under conditions involving physical central lane separation and physical bike lane separation.These findings offer a novel approach for identifying bicycle riding behaviors and analyzing their influencing factors,providing effective technical support for non-motorized traffic management and infrastructure optimization.
文摘Two environmentalists using bamboo bicycles to promote green transportation.THE exhaust emissions generated by transporting the world’s population on a daily basis are one of the main sources of greenhouse gases.Vehicles such as cars,subways,and motorcycles,all produce carbon emissions.
文摘CHINA.Bicycle Output.China’s bicycle production saw solid growth last year,increasing by 0.4 percent year on year to reach 99.54 million units,said Zheng Xiaoling,spokesperson for the China Bicycle Association.
文摘Designed and built by eight Dutch engineers,the worlds longest bicycle is 55.16 meters,roughly the same length as four double-decker buses.39-year-old Ivan Schalk had been thinking about building the world's longest bicycle since reading about it in The Guinness Book of Records when he was a child,but he only started this project in 2018,as a way to fill up his free time.
基金National Natural Science Foundation of China(Nos.22001177,22203023)Guangdong Pearl River Talent Program(no.2021QN020268)+3 种基金the Natural Science Foundation of Guangdong Province(Nos.2024A1515012381,2022A1515011859)Shenzhen Bay Laboratory Startup Fund(No.S201100003)Major Program of Shenzhen Bay Laboratory(No.S211101001-4)Shenzhen Bay Qihang Fellow Program(No.QH23001)for generous financial support.
文摘Chiral aryl cyclohex-3-en ether scaffold is widely present in bioactive natural products and drugs.The exploitation of efficient and enantioselective methods for the construction of aryl cyclohex-3-en ether scaffold is significant.Herein we disclose a chiral N,N’-dioxide/Lewis acid complex-catalyzed asymmetric inverse-electron-demand Diels-Alder(IEDDA)reaction using electron-deficient 3-carboalkoxyl-2-pyrones and less electron-enriched aryl enol ethers as reactants.A wide range of non-and 1,2-disubstituted acyclic aryl enol ethers are applicable to deliver diverse chiral bridged bicyclic lactones in high yields and stereoselectivities(up to 96%yield,>20:1 dr,97:3 er).The bridged bicyclic lactone core can be easily converted into chiral aryl cyclohex-3-en ether scaffold.Notably,DFT calculations revealed a stepwise and endo mechanism to explain the high enantioselectivity controlled by the cooperative effect of the steric factors and the dispersion interactions between ligands and enol ethers.
基金supported by the Ningxia Key Research and Development Program(Talent Introduction Special Project)Project(2022YCZX0013)North Minzu University 2022 School-Level Scientific Research Platform“Digital Agriculture Enabling Ningxia Rural Revitalization Innovation Team”(2022PT_S10)+1 种基金Yinchuan City University-Enterprise Joint Innovation Project(2022XQZD009)Ningxia Key Research and Development Program(Key Project)Project(2023BDE02001).
文摘Wearing helmetswhile riding electric bicycles can significantly reduce head injuries resulting fromtraffic accidents.To effectively monitor compliance,the utilization of target detection algorithms through traffic cameras plays a vital role in identifying helmet usage by electric bicycle riders and recognizing license plates on electric bicycles.However,manual enforcement by traffic police is time-consuming and labor-intensive.Traditional methods face challenges in accurately identifying small targets such as helmets and license plates using deep learning techniques.This paper proposes an enhanced model for detecting helmets and license plates on electric bicycles,addressing these challenges.The proposedmodel improves uponYOLOv8n by deepening the network structure,incorporating weighted connections,and introducing lightweight convolutional modules.These modifications aim to enhance the precision of small target recognition while reducing the model’s parameters,making it suitable for deployment on low-performance devices in real traffic scenarios.Experimental results demonstrate that the model achieves an mAP@0.5 of 91.8%,showing an 11.5%improvement over the baselinemodel,with a 16.2%reduction in parameters.Additionally,themodel achieves a frames per second(FPS)rate of 58,meeting the accuracy and speed requirements for detection in actual traffic scenarios.
基金supported by the New Energy Vehicle Power Battery Life Cycle Testing and Verification Public Service Platform Project[2022-235-224]the Beijing Science and Technology Planning Project[Z221100005222004]+1 种基金the Key Technologies Research and Development Program[2021YFB2012504]the Beijing Goldenbridge Project[ZZ2023002]。
文摘In this study,a detailed analysis of the combustion behaviors of the lithium iron phosphate(LFP)and lithium manganese oxide(LMO)batteries used in electric bicycles was conducted.This research included quantitative measurements of the combustion duration,flame height,combustion temperature,heat release rate,and total heat release.The results indicated that LMO batteries exhibited higher combustion temperatures of 600–700°C,flame heights of 70–75 cm,a significantly higher heat release rate of40.1 k W(12 Ah),and a total heat release of 1.04 MJ(12 Ah)compared to LFP batteries with the same capacity.Based on these experimental results,a normalized total heat release(NORTHR)parameter was proposed,demonstrating good universality for batteries with different capacities.Utilizing this parameter,quantitative calculations and optimization of the extinguishing agent dosage were conducted for fires involving these two types of batteries,and the method was validated by extinguishing fires for these two types of battery packs with water-based extinguishing fluids.
基金the National Natural Science Foundation of China(Nos.92056116,21871194,21971169)National Key Research and Development Program of China(No.2017YFA0505903).
文摘Four pillar[5]arene-based bicyclic compounds,so-called molecular universal joint(MUJ),were synthesized by incorporating a bisamide ring containing N,O,or S-heteroatom groups,which served as stimuli-responsive chiroptical molecular devices.The structure of MUJ was confirmed by 1H NMR spectra and single-crystal X-ray diffraction analysis,and their planar-chiral enantiomers were successfully separated.Chiroptical inversion behaviors from in to out configurations triggered by temperature,solvent,and vip complexation were investigated by circular dichroism spectra.Chiroptical inversion could be realized in the presence of adiponitrile in certain solvents due to the solvation effects on the side ring and the threading of the vip into the pillar[5]arene cavity.However,the stronger self-included interactions between the cavity and the inside ring of certain MUJs led to inhibition of the switching.
基金the Anhui University of Traditional Chinese Medicine High Level Talent Support Program Project(No.2021rcybO1)the National Natural Science Foundation of China(No.42075113,No.91544228)Scientific Research Program of Higher Education Institutions in Anhui Province(2023AH050836).
文摘M-xylene bicyclic peroxy radical(M-BPR)is an important atmospheric intermediate formed by the oxidation of m-xylene,which plays an important role in the new particle formation and growth of secondary organic aerosol.In this work,the reaction mechanism,thermodynamic analysis,and kinetics of the reaction between M-BPR and HO_(2)were investigated at the CCSD(T)/cc-pVDZ//B3LYP/6-311G(d,p)level of theory coupled with transition state theory.The calculated results indicate that the title reaction can occur on both singlet and triplet potential energy surfaces,and the formation of hydroperoxides and 3O_(2)via triplet state is the main reaction channel,while the other four singlet product channels are negligible due to the higher barrier heights.Additionally,the reaction rate constants are estimated by using the transition state theory over the temperature range of 258 K to 378 K,and reaction rate constants arc found to be negatively correlated with temperature.At 298 K,the total rate constant for the title reaction is 1.86×10^(-11)cm^(3)·molecule^(-1)·s^(-1).The calculated rate constants over the studied temperature range were used to fit the data and the three-parameter Arrhenius ex-studied is obtainted to be k(T)=4.22×10^(-15)·(T/300)^(1.44)·exp(2505/T).
文摘Objectives: The primary objective was to characterize the range of Knowledge, Attitude, and Practice (KAP) of Helmet use in children amongst parents to prevent head injuries and death. Methods: This is a cross-sectional study, done by online survey using a snowball sampling technique, the number of included responses were 386 parents (Male and female) living in Riyadh Aged 21 - 60 years old or above. Results: The study showed that there is a difference in Parents’ belief in the importance of helmet use while riding a Bicycle vs Motorcycle/Quad bike and that was affected by parents’ education level, almost all the people who answered the survey (76.7%) agree that it is important for their children to wear a helmet when riding both a Bicycle and a Motorcycle or Quadbike with a cumulative percentage of (93.8%). And almost all agreed on multiple approaches to help increase helmet use be it by forcing rental shops to give out helmets, forcing sellers to recommend the use of helmets, increasing awareness campaigns, and imposing fines for not wearing helmets. Conclusions: This study is the first to explore Family helmet use while riding Bicycles and Motorcycles/Quad bikes. Although Parent’s belief in the importance of helmet use for their children was high, it is clear that the level of practice is low. With that the risk of head injuries might be high, our findings suggest that safety interventions for increasing pediatric helmet use are needed to increase helmet use and reduce the risk of head injury and hospitalization.
文摘In recent years,disorderly parking and difficult charging of electric bicycles have been challenges in urban management.The rapid growth of electric bicycles is in contradiction with the lack of dedicated parking spaces and charging service facilities in towns and villages.To solve the issue of parking and charging electric bicycles in limited urban and rural spaces,prefabricated building technology is applied to the design of a multi-story electric bicycle parking lot.The multi-story prefabricated electric bicycle parking lot is utilized in urban and rural planning and design to upgrade parking facilities in old urban areas,land-constrained commercial areas,as well as counties,towns,and rural areas with inadequate municipal facilities.Multi-story prefabricated electric bicycle parking lots are the application exploration of industrial buildings,and promote the high-quality development planning and construction of towns and counties and villages.Compared with the single-story metal charging station,the multi-story assembled electric bicycle parking lot has the characteristics of integrating parking and charging,being more durable and safer in structure,accommodating a large number of vehicles,and improving the space utilization rate.
文摘The system of public bicycles in the world known as"Bicycle sharing",is a service in which bicycles are made available for shared use to individuals with or without a certain fee.Users can take and return the bike at numerous locations in the urban parts of the city.As part of the CIVITAS ELAN project(2008-2012),which was aimed at improving the quality of life of citizens by establishing high-quality solutions in city traffic and to promote and encourage sustainable,clean and energy-efficient modes of traffic,a pilot project of student public bicycle(Studocikl)was implemented at the University of Zagreb.In the first phase the pilot project included the Faculty of Transport and Traffic Sciences(FTTS)where is currently implemented.In the second phase the project is planned to include the remaining faculties located at the Borongaj Campus.The idea behind the Studocikl project is to connect two remote locations of FTTS,between headquarters in Vukelićeva Street and Borongaj Campus.Registration(login,logout)of users and the entire administration is done through a web portal.Time of using bicycles is in the period from 8 am to 8 pm(working hours of FTTS).Studocikl was officially put into operation on the 17 September 2012 and in this paper will analyse its one-year operation.The paper will also make proposals for further Studocikl development in terms of:installing GPS trackers for satellite bicycle tracking,the application for smartphones,full automation of the registration,and explore the possibility of extending such service and modes of transportation at all faculties in the University of Zagreb.
文摘Drawing upon Donna Haraway’s cyborg theory,this paper argues that the bicycle can be conceived as a cyborg extension of body and identity which transcended its mechanical essence to become an integral co-partner for women involved in resistance activities in WWII.More specifically,the study explores how women used cycling during World War Ⅱ not only for mobility but as a profound expression of courage,endurance and solidarity which enabled them to overcome physical and symbolic barriers under totalitarian regimes.The bicycle emerges not only as a central co-agent but also actively co-creates the situations in which it emerges as a transformative force.Cycling acted as a catalyst for personal and collective empowerment,fostering new subjectivities while transcending physical and social limitations.This study sparks multidimensional discourse on how technological tools can co-create our societies and identities,offering insights into how bicycles can drive socio-political change,promote emancipation and foster inclusivity.
基金We thank the National Science Foundation of China(NSFC,N0.20372003)for financial support.
文摘Aim To develop a concise method for the synthesis of bicyclic azasugar and thiosugar with novel scaffold. Methods The two primary hydroxyl groups of compound 1 were selectively protected with tosyl cloloride in pyridine, followed by ring-closure with sodium sulfide or primary amine to form the oxy-bridged bicyclic molecules in good yields. Results Two bicyclic azasugars and a thiosugar were produced from L-sorbose in several steps. Conclusion The described procedures provide an efficient method to synthesize bicyclic azasugar and thiosugar with novel scaffold as potential glycosidase inhibitors.
基金supported by the Natural Science Foundation of Anhui Province Education Department(No.KJ2014A141)the National Natural Science Foundation of China(No.21171008)
文摘The bicyclic product containing a chromene skeleton and a propargylamine skeleton（C（22）H（22）N2O2） was synthesized from the double sites of terminal alkyne, piperazine derivative and formaldehyde via one-pot procedure. Its structure was characterized by ^1H NMR, ^13C NMR, IR and H RMS, and further confirmed by single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group P21/n with a = 12.6571（14）, b = 11.3249（12）, c = 12.6571（14） A, β = 105.22°,V = 1750.6（3） A^3, Z = 4, R = 0.0568 and w R = 0.1444. The fluorescence of the product was discussed.
