Aluminum(Al) particles are good fuel additives to improve the energy output performances of explosives. Under detonation environment, reaction delay of Al particles plays a key role in the energy release efficiency. U...Aluminum(Al) particles are good fuel additives to improve the energy output performances of explosives. Under detonation environment, reaction delay of Al particles plays a key role in the energy release efficiency. Up to date, reaction delay of Al particles is still limited by the efficiency of mass and heat transfer from oxidizers to Al particles. To address this issue, a homogeneous fuel-oxidizer assembly has recently become a promising strategy. In this work, oxidizer-activated Al fuel particles(ALG) were prepared with glycidyl azide polymer(GAP) as the oxidizer. The ALG was in uniform spherical shape and core-shell structure with shell layer of around 5 nm which was observed by scanning electron microscope and transmission electron microscope. The localized nanoscale mid-IR measurement detected the uniform distribution of characteristic absorption bond of GAP in the shell layer which confirmed the homogenous fuel-oxidizer structure of ALG. A thermal gravimetric analysis of ALG at ultrafast heating rate of 1000℃/min under argon atmosphere was conducted. The decomposition of GAP finished much earlier than that of GAP at heating rate of 10℃/min. Under ultrafast high laser fluence, the reaction response of ALG was characterized and compared with that of micro-sized Al(μAl). With the increase of laser energy, the propagation distance of the shock wave increased. However, the velocity histories were nearly the same when energies were lower than 299 mJ or higher than 706 mJ. The propagation distance of the shock wave for ALG was 0.5 mm larger than that for μAl at 2.1 μs. The underwater explosion showed the peak pressure and the shock wave energy of the ALG-based explosive were both higher than those of the μAl-based explosive at 2.5 m. This study shows the feasibility to improve the energy release of Al-based explosives via using the oxidizer-activated Al fuel particles with energetic polymer as the oxidizer.展开更多
The thermal stability of normal lead styphnate( N-LTNR) has been studied under severe temperature(- 70 ℃- 130 ℃ for 5 days) with a high optical microscope and camera were used to observe apparent morphology and ther...The thermal stability of normal lead styphnate( N-LTNR) has been studied under severe temperature(- 70 ℃- 130 ℃ for 5 days) with a high optical microscope and camera were used to observe apparent morphology and thermal gravimetric analysis was applied to study the physical changes. In addition,vacuum stability analysis,differential scanning calorimetry( DSC),thermal gravimetric analysis( TGA) and purity analysis were utilized to study the chemical changes. As well as flame sensitivity analysis were used to investigated the explosive changes. The results show that N-LTNR has good chemical stability and fire function stability between- 70 ℃ and 130 ℃,but poor physical stability. When the temperature was exceeded than 110 ℃,the N-LTNR lost crystal water which made the energetic material become darker in color,lager in volume and lighter in weight( 3. 416%) when the temperature was below- 40 ℃,the phenomenon of crystal broking and jumping happened.展开更多
A screening of environmental conditions that would elicit robust biofilm in a collection of Serratia marcescens isolated from soil revealed that exogenous milk protein increased biofilm productivity up to ten-fold. A ...A screening of environmental conditions that would elicit robust biofilm in a collection of Serratia marcescens isolated from soil revealed that exogenous milk protein increased biofilm productivity up to ten-fold. A select screening of fish pathogens, freshwater and human isolates identified several other species that responded similarly to exogenous protein. The optimal protein concentration was species specific;S. marcescens at 5% milk protein, Aeromonas sp. at 2% - 3%, Flavobacterium columnare at 1% and Pseudomonas aeruginosa at 0.1% - 0.4%. Media supplemented with milk protein also increased the cell counts in biofilm as well as the protein incorporated into the biofilm matrix. These data suggest that relatively high concentrations of exogenous protein may serve as an environmental trigger for biofilm formation, particularly for pathogenic bacteria exposed to relatively high concentrations of protein in bodily fluids and mucosal surfaces.展开更多
Although stimulus frequency otoacoustic emissions(SFOAEs)have been used as a non-invasive measure of cochlear mechanics,clinical and experimental application of SFOAEs has been limited by difficulties in accurately de...Although stimulus frequency otoacoustic emissions(SFOAEs)have been used as a non-invasive measure of cochlear mechanics,clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal.In this study,a novel signal processing method for multicomponent analysis(MCA)was used to measure the amplitude and delay of the SFOAE.This report shows the delay-frequency distribution of the SFOAE measured from the human ear.A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE,strongly indicating that the SFOAE was generated at characteristic frequency locations.Information derived from this method may reveal more details of cochlear mechanics in the human ear.展开更多
Stimulus-Response Compatibility (SRC) refers to the fact that some tasks are performed easier and better than others because of the way stimuli and responses are paired with each other. To assess the brain responses t...Stimulus-Response Compatibility (SRC) refers to the fact that some tasks are performed easier and better than others because of the way stimuli and responses are paired with each other. To assess the brain responses to stimulus-response conflicts, we investigated the behavioral (accuracy and Reaction Times: RTs) as well as the physiological response (Lateralized Readiness Potentials: LRP) modulations in a positional blocked and a conditional mixed design in twelve university students. Results revealed that the performance was less accurate and the RTs, as well as the LRP onset, were delayed under the mixed conditional design. A greater compatibility effect was also noted on accuracy, RTs and LRP onset latency in the mixed design. Consistent with these findings, smaller peak activation at fronto-central areas suggests that more selective inhibition is needed in a mixed design context. Despite a smaller activation, the topographical distribution is similar in both designs. These results indicate that the translation time between stimulus- and response codes are greater under the mixed instruction, while the similar LRP topography suggests that common neural structures underlie LRPs in response to both type of designs.展开更多
Support SMEs Increase the scale of financial supports at various levels to support SMEs, sustain light & textile projects with promising market prospect, notable driving of employment and remarkable social benefit...Support SMEs Increase the scale of financial supports at various levels to support SMEs, sustain light & textile projects with promising market prospect, notable driving of employment and remarkable social benefits, and step up investments in construction of credit guarantee system and service展开更多
Based on our preceding studies on the aerodynamics of a falcoperegrinus in diving flight along a vertical dam it is known that even when the body shape of the bird is rather streamlined in V-shape some feathers tips m...Based on our preceding studies on the aerodynamics of a falcoperegrinus in diving flight along a vertical dam it is known that even when the body shape of the bird is rather streamlined in V-shape some feathers tips may elevate in certain regions of the body. These regions were identified in wind tunnel tests for typical diving flight conditions as regions of locally separated flow. A life-size model in V-shape of a falcoperegrinus with artificial feathers fixed along the body was studied in a wind tunnel to focus on the fluid-structure interaction of feathers located in this sector. The distal ends of the feathers show flow-induced vibrations at typical flight conditions which grow linear in amplitude with increasing angle of incidence until incipient separation. In light of the proven existence of vibration-sensitive mechanoreceptors in the follicles of secondary feathers in birds it is hypothesized that this linear amplitude response offers the bird to sense the angle of incidence during the diving flight using the vibration magnitude as sensory stimulus. Thus the bird in streamlined shape has still a good measure to control its attitude to be in the narrow window of safe angle of incidence. This might have implications also for other birds or technical applications of airfoil sensors regarding incipient separation detection.展开更多
The State Council conducted researches and deployed measures to further expand domestic demand to facilitate steadfast economic growth, as well as nailed down ten measures, which will invest in a total of RMB four tri...The State Council conducted researches and deployed measures to further expand domestic demand to facilitate steadfast economic growth, as well as nailed down ten measures, which will invest in a total of RMB four trillion Yuan till the end of 2010 to stimulate domestic demand. Following that, the State Council issued six policies and measures to promote sound development of the light industry and other industries, like textile industry. This enables us to see the determination and action of the government in combating the financial storm and developing the social economy. Meanwhile, it is a good news to the textile industry in unfavorable situation, which can be deemed as an unprecedented powerful policy supports. Absolutely, this will bring a opportunity to China's textile industry. Therefore, we pick out items closely interrelated to the textile industry from the "10+6" policy for elaboration, so as to work out how we shall take full advantage of the supports. Wherein, the ten measures to expand domestic demand do not directly target the textile industry, but they will, with the implementation of various policies and investments, surely drive domestic demand to grow, and contribute to the growth of textile industry.展开更多
Understanding and tuning charge transport over a single molecule is a fundamental topic in molecular electronics.Single-molecule junctions composed of individual molecules attached to two electrodes are the most commo...Understanding and tuning charge transport over a single molecule is a fundamental topic in molecular electronics.Single-molecule junctions composed of individual molecules attached to two electrodes are the most common components built for single-molecule charge transport studies.During the past two decades,rapid technical and theoretical advances in single-molecule junctions have increased our understanding of the conductance properties and functions of molecular devices.In this perspective article,we introduce the basic principles of charge transport in single-molecule junctions,then give an overview of recent progress in modulating single-molecule transport through external stimuli such as electric field and potential,light,mechanical force,heat,and chemical environment.Lastly,we discuss challenges and offer views on future developments in molecular electronics.展开更多
Eliminating colloidal toxicity and enabling its intrinsic fluorescence in aggressive environmental conditions are the key challenges for commercializing hydrophobic cadmium based quantum dots(QD).Polyarylene ether nit...Eliminating colloidal toxicity and enabling its intrinsic fluorescence in aggressive environmental conditions are the key challenges for commercializing hydrophobic cadmium based quantum dots(QD).Polyarylene ether nitriles(PEN)are an example of super-engineering thermoplastics that possess a unique combination of thermal stability,intrinsic fluorescence,biocompatibility and distinct emulsion self-assembly feature.Herein,the co-self-assembly of amphiphilic PEN with hydrophobic CdSe@ZnS QD,confined in the three-dimensional(3D)oil-in-water emulsion droplets,has been explored tofabricate fluorescent microparticles(FMP).It was found that these FMP demonstrated good biocompatibility(cell viability above 90%),while exhibiting a fluorescence emission in aqueous solution that was retained(intensity retention ratio above 80%)within the whole pH range of 1-14,as well as,after being subjected to autoclaving at 120℃for 1 h.Interestingly,it was discovered that introduction of calcium ions in the emulsion self-assembly contributed to in-situ generation of phase changing nanoplates inside the FMP,which led to the photo-thermal modulated solid state fluorescence from drop-casted FMP film.Thanks to their versatile fluorescence,these FMP colloids were exploited as fluorescent probes for macrophages imaging,while micro-patterns with reversible changing of emission color were induced via thermal treatment and direct laser lithography.展开更多
Previous study demonstrated mesenchymal stem cells were sensitive to mechanical stimulus, and mechanical stimulus played great role in differentiation of mesenchymal stem cells.
Stimulus re s ponsive materials can provide a variety of desirable properties in one equipment unit,such as optoelectronic devices,data communications,actuators,memories,sensors and capacitors.However,it remains a lar...Stimulus re s ponsive materials can provide a variety of desirable properties in one equipment unit,such as optoelectronic devices,data communications,actuators,memories,sensors and capacitors.However,it remains a large challenge to design such stimulus responsive materials,especially functional materials having both dielectric switch and second harmonic generation(SHG).Here,a new stimuli-responsive switchable material [(CH_(3))_(3)N(CH_(2))_(2)Cl]_(2)]Mn(SCN)_(4)(H_(2)O)_(2)] was discovered as a potential secondharmonic generation(SHG) dielectric switch.It is worth noting that it has SHG characteristics before and after undergoing reversible high-temperature phase transitions.In this work,we successfully refined the tetramethylammonium cation to obtain a quasi-spherical cation,which is tetramethylchloroethylamine(TMCEM) cation.By substituting H with a halogen,the increased steric hindrance of the molecular makes energy barrier increased,resulting in the reversible high-temperature phase transition.At the same time,the interactions of quasi-spherical cations and [Mn(SCN)_(4)(H_(2)O)_(2)]^(2-) anions affect a noncentrosymmetric structure to induce the SHG effect.These findings provide a new approach to design novel functional switch materials.展开更多
A H_(2)O_(2)-triggered stimulus response electrochemiluminescence(ECL)sensor for sensitive detection of cancer cells using mesoporous silica nanoparticles(MSNs)has been proposed.ECL signal-generating molecules(Ru(phen...A H_(2)O_(2)-triggered stimulus response electrochemiluminescence(ECL)sensor for sensitive detection of cancer cells using mesoporous silica nanoparticles(MSNs)has been proposed.ECL signal-generating molecules(Ru(phen)32+)were encap-sulated into phenylboronic acid group-functionalized MSNs(PBA-MSNs)porous and capped by polyhydroxy functioned Au nanoparticles(AuNPs)through the interaction of carbohydrate-boronic acid first.Brunauer-Emmett-Teller(BET)and transmission electron microscopy(TEM)were applied to characterize the materials.The proposed controlled release sensing platform shows approximately no leakage from the mesoporrs of MSNs after a long time of storage.Cancer cells are initially incubated with the functionalized MSNs and then treated with ascorbic acid to endogenously produce H_(2)O_(2).Arylboronic esters in the MSNs surface can be oxidized by the produced H_(2)O_(2),causing the releasing of the molecule from MSNs and increased ECL signal.This technique displayed an excellent measurement for the breast cancer cells’sensitive diagnosis with a detection limit of 208 cells/mL.The phenomenon suggests that this sensing platform may be potentially applied for breast cancer sensitive detection in the future.展开更多
Although China’s local governments are facing greater financial pressure,they often sell industrial land at low prices to attract investment.Local government land transfer strategies refl ect driving mechanisms of of...Although China’s local governments are facing greater financial pressure,they often sell industrial land at low prices to attract investment.Local government land transfer strategies refl ect driving mechanisms of officials’behavior.Based on the micro data of about 340000 industrial land sales in 289 prefecture-level cities in China from 2006 to 2015,this paper divides industrial land transfer into two categories,namely land transfer with the aim of attracting investment and normal transfer,according to whether the transfer price is lower than the minimum price stipulated by central government.The paper explores the strategies of industrial land transfer under financial pressure and the motivation differences of officials with the help of changes in local land transfers after the introduction of economic stimulus policies.It is found that financial pressure will signifi cantly reduce local industrial land transfer with the aim of investment attraction.However,after the introduction of economic stimulus policies,although financial pressure has increased,the infl uence of financial pressure on local governments’investment-induced land transfer behavior significantly weakened due to the increase of out-of-system financing channels,thus industrial land transfer with the aim of attracting investment has increased signifi cantly.From the perspective of promotion incentives of officials,officials with longer term were more inclined to sell industrial land to attract investment.Therefore,it is necessary to rationally arrange the financial resources and powers of central and local governments,to adapt reasonable macro control method and strategy,and to build an offi cial evaluation system that meets the needs of high-quality development.展开更多
Steady-state visual evoked potential(SSVEP)-based brain-computer interfaces(BCIs)have been widely studied.Considerable progress has been made in the aspects of stimulus coding,electroencephalogram processing,and recog...Steady-state visual evoked potential(SSVEP)-based brain-computer interfaces(BCIs)have been widely studied.Considerable progress has been made in the aspects of stimulus coding,electroencephalogram processing,and recognition algorithms to enhance system performance.The properties of SSVEP have been demonstrated to be highly sensitive to stimulus luminance.However,thus far,there have been very few reports on the impact of background luminance on the system performance of SSVEP-based BCIs.This study investigated the impact of stimulus background luminance on SSVEPs.Specifically,this study compared two types of background luminance,i.e.,(1)black luminance[red,green,blue(rgb):(0,0,0)]and(2)gray luminance[rgb:(128,128,128)],and determined their effect on the classification performance of SSVEPs at the stimulus frequencies of 9,11,13,and 15 Hz.The offline results from nine healthy subjects showed that compared with the gray background luminance,the black background luminance induced larger SSVEP amplitude and larger signal-to-noise ratio,resulting in a better classification accuracy.These results suggest that the background luminance of visual stimulus has a considerable effect on the SSVEP and therefore has a potential to improve the BCI performance.展开更多
Officials and experts discuss obstacles and solutions in China’s economic growth china may have impressed the world with its rapid recovery that helped lead the global economy out of the financial storm, but now
China is introducing a fiscal stimulus plan to keep its economy from slumping The Chinese Government hopes to save the economy from further slowdowns with a fiscal stimulus package worth approximately 4 trillion yuan ...China is introducing a fiscal stimulus plan to keep its economy from slumping The Chinese Government hopes to save the economy from further slowdowns with a fiscal stimulus package worth approximately 4 trillion yuan ($586 billion) to boost domestic demand. It was agreed on November 5 at an executive meeting of the State Council presided over by Premier Wen Jiabao that China must adopt "flexible and prudent" macro-control policies, given the volatile world situation and grim global economic outlook.展开更多
Efforts will be made to ensure steady operation in the nonferrous metal sector in 2009,and lay the basis for the industry’s sustainable development by 2011.
基金National Natural Science Foundation of China(Grant No.11832006,U1530262,21975024).
文摘Aluminum(Al) particles are good fuel additives to improve the energy output performances of explosives. Under detonation environment, reaction delay of Al particles plays a key role in the energy release efficiency. Up to date, reaction delay of Al particles is still limited by the efficiency of mass and heat transfer from oxidizers to Al particles. To address this issue, a homogeneous fuel-oxidizer assembly has recently become a promising strategy. In this work, oxidizer-activated Al fuel particles(ALG) were prepared with glycidyl azide polymer(GAP) as the oxidizer. The ALG was in uniform spherical shape and core-shell structure with shell layer of around 5 nm which was observed by scanning electron microscope and transmission electron microscope. The localized nanoscale mid-IR measurement detected the uniform distribution of characteristic absorption bond of GAP in the shell layer which confirmed the homogenous fuel-oxidizer structure of ALG. A thermal gravimetric analysis of ALG at ultrafast heating rate of 1000℃/min under argon atmosphere was conducted. The decomposition of GAP finished much earlier than that of GAP at heating rate of 10℃/min. Under ultrafast high laser fluence, the reaction response of ALG was characterized and compared with that of micro-sized Al(μAl). With the increase of laser energy, the propagation distance of the shock wave increased. However, the velocity histories were nearly the same when energies were lower than 299 mJ or higher than 706 mJ. The propagation distance of the shock wave for ALG was 0.5 mm larger than that for μAl at 2.1 μs. The underwater explosion showed the peak pressure and the shock wave energy of the ALG-based explosive were both higher than those of the μAl-based explosive at 2.5 m. This study shows the feasibility to improve the energy release of Al-based explosives via using the oxidizer-activated Al fuel particles with energetic polymer as the oxidizer.
文摘The thermal stability of normal lead styphnate( N-LTNR) has been studied under severe temperature(- 70 ℃- 130 ℃ for 5 days) with a high optical microscope and camera were used to observe apparent morphology and thermal gravimetric analysis was applied to study the physical changes. In addition,vacuum stability analysis,differential scanning calorimetry( DSC),thermal gravimetric analysis( TGA) and purity analysis were utilized to study the chemical changes. As well as flame sensitivity analysis were used to investigated the explosive changes. The results show that N-LTNR has good chemical stability and fire function stability between- 70 ℃ and 130 ℃,but poor physical stability. When the temperature was exceeded than 110 ℃,the N-LTNR lost crystal water which made the energetic material become darker in color,lager in volume and lighter in weight( 3. 416%) when the temperature was below- 40 ℃,the phenomenon of crystal broking and jumping happened.
文摘A screening of environmental conditions that would elicit robust biofilm in a collection of Serratia marcescens isolated from soil revealed that exogenous milk protein increased biofilm productivity up to ten-fold. A select screening of fish pathogens, freshwater and human isolates identified several other species that responded similarly to exogenous protein. The optimal protein concentration was species specific;S. marcescens at 5% milk protein, Aeromonas sp. at 2% - 3%, Flavobacterium columnare at 1% and Pseudomonas aeruginosa at 0.1% - 0.4%. Media supplemented with milk protein also increased the cell counts in biofilm as well as the protein incorporated into the biofilm matrix. These data suggest that relatively high concentrations of exogenous protein may serve as an environmental trigger for biofilm formation, particularly for pathogenic bacteria exposed to relatively high concentrations of protein in bodily fluids and mucosal surfaces.
基金Supported in part by research grants from the National Institute of Deafness and Other Communication Disorders(R01 DC 00141 and R03 DC033642)the National Institutes of Health+2 种基金the Research Fund of the American Otological Societythe Medical Research Foundation of OregonVA RR&D Center Grant RCTR-597-0160,Portland,VAMC
文摘Although stimulus frequency otoacoustic emissions(SFOAEs)have been used as a non-invasive measure of cochlear mechanics,clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal.In this study,a novel signal processing method for multicomponent analysis(MCA)was used to measure the amplitude and delay of the SFOAE.This report shows the delay-frequency distribution of the SFOAE measured from the human ear.A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE,strongly indicating that the SFOAE was generated at characteristic frequency locations.Information derived from this method may reveal more details of cochlear mechanics in the human ear.
文摘Stimulus-Response Compatibility (SRC) refers to the fact that some tasks are performed easier and better than others because of the way stimuli and responses are paired with each other. To assess the brain responses to stimulus-response conflicts, we investigated the behavioral (accuracy and Reaction Times: RTs) as well as the physiological response (Lateralized Readiness Potentials: LRP) modulations in a positional blocked and a conditional mixed design in twelve university students. Results revealed that the performance was less accurate and the RTs, as well as the LRP onset, were delayed under the mixed conditional design. A greater compatibility effect was also noted on accuracy, RTs and LRP onset latency in the mixed design. Consistent with these findings, smaller peak activation at fronto-central areas suggests that more selective inhibition is needed in a mixed design context. Despite a smaller activation, the topographical distribution is similar in both designs. These results indicate that the translation time between stimulus- and response codes are greater under the mixed instruction, while the similar LRP topography suggests that common neural structures underlie LRPs in response to both type of designs.
文摘Support SMEs Increase the scale of financial supports at various levels to support SMEs, sustain light & textile projects with promising market prospect, notable driving of employment and remarkable social benefits, and step up investments in construction of credit guarantee system and service
文摘Based on our preceding studies on the aerodynamics of a falcoperegrinus in diving flight along a vertical dam it is known that even when the body shape of the bird is rather streamlined in V-shape some feathers tips may elevate in certain regions of the body. These regions were identified in wind tunnel tests for typical diving flight conditions as regions of locally separated flow. A life-size model in V-shape of a falcoperegrinus with artificial feathers fixed along the body was studied in a wind tunnel to focus on the fluid-structure interaction of feathers located in this sector. The distal ends of the feathers show flow-induced vibrations at typical flight conditions which grow linear in amplitude with increasing angle of incidence until incipient separation. In light of the proven existence of vibration-sensitive mechanoreceptors in the follicles of secondary feathers in birds it is hypothesized that this linear amplitude response offers the bird to sense the angle of incidence during the diving flight using the vibration magnitude as sensory stimulus. Thus the bird in streamlined shape has still a good measure to control its attitude to be in the narrow window of safe angle of incidence. This might have implications also for other birds or technical applications of airfoil sensors regarding incipient separation detection.
文摘The State Council conducted researches and deployed measures to further expand domestic demand to facilitate steadfast economic growth, as well as nailed down ten measures, which will invest in a total of RMB four trillion Yuan till the end of 2010 to stimulate domestic demand. Following that, the State Council issued six policies and measures to promote sound development of the light industry and other industries, like textile industry. This enables us to see the determination and action of the government in combating the financial storm and developing the social economy. Meanwhile, it is a good news to the textile industry in unfavorable situation, which can be deemed as an unprecedented powerful policy supports. Absolutely, this will bring a opportunity to China's textile industry. Therefore, we pick out items closely interrelated to the textile industry from the "10+6" policy for elaboration, so as to work out how we shall take full advantage of the supports. Wherein, the ten measures to expand domestic demand do not directly target the textile industry, but they will, with the implementation of various policies and investments, surely drive domestic demand to grow, and contribute to the growth of textile industry.
基金This work was supported by the National Natural Science Foundation of China(21788102,21790361,22175064,22073109,and 92161122)Shanghai Municipal Sci.&Tech.Major Project(2018SHZDZX03)+1 种基金the 111 Project(B16017)the Fundamental Research Funds for the Central Universities.
文摘Understanding and tuning charge transport over a single molecule is a fundamental topic in molecular electronics.Single-molecule junctions composed of individual molecules attached to two electrodes are the most common components built for single-molecule charge transport studies.During the past two decades,rapid technical and theoretical advances in single-molecule junctions have increased our understanding of the conductance properties and functions of molecular devices.In this perspective article,we introduce the basic principles of charge transport in single-molecule junctions,then give an overview of recent progress in modulating single-molecule transport through external stimuli such as electric field and potential,light,mechanical force,heat,and chemical environment.Lastly,we discuss challenges and offer views on future developments in molecular electronics.
基金the National Natural Science Foundation of China(No.51403029)the Fundamental Research Funds for the Central Universities(No.ZYGX2019J026)+1 种基金Sichuan Science and Technology Program(No.2020YFG0100)International Science and Technology Cooperation Project from Chengdu municipal government(No.2019-GH02-00037-HZ).K.J.thanks Prof.Yanbo Li from the IoF of UESTC for his timely assistance in fluorescence lifetime measurement.
文摘Eliminating colloidal toxicity and enabling its intrinsic fluorescence in aggressive environmental conditions are the key challenges for commercializing hydrophobic cadmium based quantum dots(QD).Polyarylene ether nitriles(PEN)are an example of super-engineering thermoplastics that possess a unique combination of thermal stability,intrinsic fluorescence,biocompatibility and distinct emulsion self-assembly feature.Herein,the co-self-assembly of amphiphilic PEN with hydrophobic CdSe@ZnS QD,confined in the three-dimensional(3D)oil-in-water emulsion droplets,has been explored tofabricate fluorescent microparticles(FMP).It was found that these FMP demonstrated good biocompatibility(cell viability above 90%),while exhibiting a fluorescence emission in aqueous solution that was retained(intensity retention ratio above 80%)within the whole pH range of 1-14,as well as,after being subjected to autoclaving at 120℃for 1 h.Interestingly,it was discovered that introduction of calcium ions in the emulsion self-assembly contributed to in-situ generation of phase changing nanoplates inside the FMP,which led to the photo-thermal modulated solid state fluorescence from drop-casted FMP film.Thanks to their versatile fluorescence,these FMP colloids were exploited as fluorescent probes for macrophages imaging,while micro-patterns with reversible changing of emission color were induced via thermal treatment and direct laser lithography.
文摘Previous study demonstrated mesenchymal stem cells were sensitive to mechanical stimulus, and mechanical stimulus played great role in differentiation of mesenchymal stem cells.
基金supported by the National Natural Science Foundation of China(Nos.21673038,21771037,21805033)Natural Science Foundation of Jiangsu Province(JSNSF,No.BK20170659)。
文摘Stimulus re s ponsive materials can provide a variety of desirable properties in one equipment unit,such as optoelectronic devices,data communications,actuators,memories,sensors and capacitors.However,it remains a large challenge to design such stimulus responsive materials,especially functional materials having both dielectric switch and second harmonic generation(SHG).Here,a new stimuli-responsive switchable material [(CH_(3))_(3)N(CH_(2))_(2)Cl]_(2)]Mn(SCN)_(4)(H_(2)O)_(2)] was discovered as a potential secondharmonic generation(SHG) dielectric switch.It is worth noting that it has SHG characteristics before and after undergoing reversible high-temperature phase transitions.In this work,we successfully refined the tetramethylammonium cation to obtain a quasi-spherical cation,which is tetramethylchloroethylamine(TMCEM) cation.By substituting H with a halogen,the increased steric hindrance of the molecular makes energy barrier increased,resulting in the reversible high-temperature phase transition.At the same time,the interactions of quasi-spherical cations and [Mn(SCN)_(4)(H_(2)O)_(2)]^(2-) anions affect a noncentrosymmetric structure to induce the SHG effect.These findings provide a new approach to design novel functional switch materials.
基金supported by the National Science Foundation of China(Nos.21675028 and 21775026)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT15R11)+2 种基金the National Science Foundation of Fujian Province(No.2018J05018)the STS Key Project of Fujian Province(No.2017T3007)Provincial Health Technology Project of Fujian Province(No.2019-ZQN-93).
文摘A H_(2)O_(2)-triggered stimulus response electrochemiluminescence(ECL)sensor for sensitive detection of cancer cells using mesoporous silica nanoparticles(MSNs)has been proposed.ECL signal-generating molecules(Ru(phen)32+)were encap-sulated into phenylboronic acid group-functionalized MSNs(PBA-MSNs)porous and capped by polyhydroxy functioned Au nanoparticles(AuNPs)through the interaction of carbohydrate-boronic acid first.Brunauer-Emmett-Teller(BET)and transmission electron microscopy(TEM)were applied to characterize the materials.The proposed controlled release sensing platform shows approximately no leakage from the mesoporrs of MSNs after a long time of storage.Cancer cells are initially incubated with the functionalized MSNs and then treated with ascorbic acid to endogenously produce H_(2)O_(2).Arylboronic esters in the MSNs surface can be oxidized by the produced H_(2)O_(2),causing the releasing of the molecule from MSNs and increased ECL signal.This technique displayed an excellent measurement for the breast cancer cells’sensitive diagnosis with a detection limit of 208 cells/mL.The phenomenon suggests that this sensing platform may be potentially applied for breast cancer sensitive detection in the future.
基金Humanities and Social Sciences Research Planning Fund of the Ministry of Education:the Green Growth Effect of Regional Environmental Regulation from the Perspective of Environmental Total Factor Productivity(19YJAZH062)special fund support for basic scientific research of universities directly under the Ministry of Education(2722019PY025,2722020PY032).
文摘Although China’s local governments are facing greater financial pressure,they often sell industrial land at low prices to attract investment.Local government land transfer strategies refl ect driving mechanisms of officials’behavior.Based on the micro data of about 340000 industrial land sales in 289 prefecture-level cities in China from 2006 to 2015,this paper divides industrial land transfer into two categories,namely land transfer with the aim of attracting investment and normal transfer,according to whether the transfer price is lower than the minimum price stipulated by central government.The paper explores the strategies of industrial land transfer under financial pressure and the motivation differences of officials with the help of changes in local land transfers after the introduction of economic stimulus policies.It is found that financial pressure will signifi cantly reduce local industrial land transfer with the aim of investment attraction.However,after the introduction of economic stimulus policies,although financial pressure has increased,the infl uence of financial pressure on local governments’investment-induced land transfer behavior significantly weakened due to the increase of out-of-system financing channels,thus industrial land transfer with the aim of attracting investment has increased signifi cantly.From the perspective of promotion incentives of officials,officials with longer term were more inclined to sell industrial land to attract investment.Therefore,it is necessary to rationally arrange the financial resources and powers of central and local governments,to adapt reasonable macro control method and strategy,and to build an offi cial evaluation system that meets the needs of high-quality development.
基金This work was supported in part by National Natural Science Foundation of China(Grant No.62171473)Beijing Science and Technology Program(Grant No.Z201100004420015)Fundamental Research Funds for the Central Universities of China(Grant No.FRF-TP-20-017A1).
文摘Steady-state visual evoked potential(SSVEP)-based brain-computer interfaces(BCIs)have been widely studied.Considerable progress has been made in the aspects of stimulus coding,electroencephalogram processing,and recognition algorithms to enhance system performance.The properties of SSVEP have been demonstrated to be highly sensitive to stimulus luminance.However,thus far,there have been very few reports on the impact of background luminance on the system performance of SSVEP-based BCIs.This study investigated the impact of stimulus background luminance on SSVEPs.Specifically,this study compared two types of background luminance,i.e.,(1)black luminance[red,green,blue(rgb):(0,0,0)]and(2)gray luminance[rgb:(128,128,128)],and determined their effect on the classification performance of SSVEPs at the stimulus frequencies of 9,11,13,and 15 Hz.The offline results from nine healthy subjects showed that compared with the gray background luminance,the black background luminance induced larger SSVEP amplitude and larger signal-to-noise ratio,resulting in a better classification accuracy.These results suggest that the background luminance of visual stimulus has a considerable effect on the SSVEP and therefore has a potential to improve the BCI performance.
文摘Officials and experts discuss obstacles and solutions in China’s economic growth china may have impressed the world with its rapid recovery that helped lead the global economy out of the financial storm, but now
文摘China is introducing a fiscal stimulus plan to keep its economy from slumping The Chinese Government hopes to save the economy from further slowdowns with a fiscal stimulus package worth approximately 4 trillion yuan ($586 billion) to boost domestic demand. It was agreed on November 5 at an executive meeting of the State Council presided over by Premier Wen Jiabao that China must adopt "flexible and prudent" macro-control policies, given the volatile world situation and grim global economic outlook.
文摘Efforts will be made to ensure steady operation in the nonferrous metal sector in 2009,and lay the basis for the industry’s sustainable development by 2011.
