Tremendous efforts have been devoted to explore energy-efficient strategies of ammonia synthesis to replace Haber-Bosch process which accounts for 1.4% of the annual energy consumption. In this study, atomically dispe...Tremendous efforts have been devoted to explore energy-efficient strategies of ammonia synthesis to replace Haber-Bosch process which accounts for 1.4% of the annual energy consumption. In this study, atomically dispersed Au_1 catalyst is synthesized and applied in electrochemical synthesis of ammonia under ambient conditions. A high NH＋4 Faradaic efficiency of 11.1 % achieved by our Au_1 catalyst surpasses most of reported catalysts under comparable conditions. Benefiting from efficient atom utilization, an NH＋4 yield rate of 1,305 μg h-1 mg-1Au has been reached, which is roughly 22.5 times as high as that by sup- ported Au nanoparticles. We also demonstrate that by employing our Au_1 catalyst, NH＋4 can be electro- chemically produced directly from N_2 and H_2 with an energy utilization rate of 4.02 mmol kJ-1. Our study provides a possibility of replacing the Haber-Bosch process with environmentally benign and energy-efficient electrochemical strategies.展开更多
Reasonably constructing an atomic interface is pronouncedly essential for surface-related gas-sensing reaction.Herein,we present an ingen-ious feedback-regulation system by changing the interactional mode between sing...Reasonably constructing an atomic interface is pronouncedly essential for surface-related gas-sensing reaction.Herein,we present an ingen-ious feedback-regulation system by changing the interactional mode between single Pt atoms and adjacent S species for high-efficiency SO_(2)sensing.We found that the single Pt sites on the MoS_(2)surface can induce easier volatiliza-tion of adjacent S species to activate the whole inert S plane.Reversely,the activated S species can provide a feedback role in tailoring the antibonding-orbital electronic occupancy state of Pt atoms,thus creating a combined system involving S vacancy-assisted single Pt sites(Pt-Vs)to synergistically improve the adsorption ability of SO_(2)gas molecules.Further-more,in situ Raman,ex situ X-ray photoelectron spectroscopy testing and density functional theory analysis demonstrate the intact feedback-regulation system can expand the electron transfer path from single Pt sites to whole Pt-MoS_(2)supports in SO_(2)gas atmosphere.Equipped with wireless-sensing modules,the final Pt1-MoS_(2)-def sensors array can further realize real-time monitoring of SO_(2)levels and cloud-data storage for plant growth.Such a fundamental understanding of the intrinsic link between atomic interface and sensing mechanism is thus expected to broaden the rational design of highly effective gas sensors.展开更多
Printing techniques hold great potential in the manufacture of electronics such as sensors,micro-supercapacitors,and flexible electronics.However,developing large-scale functional conductive inks with appropriate rheo...Printing techniques hold great potential in the manufacture of electronics such as sensors,micro-supercapacitors,and flexible electronics.However,developing large-scale functional conductive inks with appropriate rheological properties and active components still remains a challenge.Herein,through optimizing the formulations of ink,iron single sites supported N-doped carbon black(Fe_(1)-NC)inks can serve as both conductive electrodes and high-reactive catalysts to realize convenient glucose detection,which pronouncedly reduces the dosage of enzyme and simplifies the sensors preparation.In detail,utilizing in-situ pyrolysis method,Fe_(1)-NC single-atom catalysts(SACs)are prepared in bulk(dekagram-level).The batched Fe_(1)-NC SACs materials can be uniformly mixed with modulated ink to realize the screen printing with high resolution and uniformity.Also,the whole scalable preparation and ink-functional process can be extended to various metals(including Co,Ni,Cu,and Mn).The introduction of highly active Fe_(1)-NC sites reduces the amount of enzyme used in glucose detection by at least 50%,contributing to the cost reduction of sensors.The strategy in harnessing the SACs onto the carbon inks thus provides a broad prospect for the low-cost and large-scale printing of sensitive sensing devices.展开更多
The application of a gate voltage to control the superconducting current flowing through a nanoscale superconducting constriction,named as gate-controlled supercurrent(GCS),has raised great interest for fundamental an...The application of a gate voltage to control the superconducting current flowing through a nanoscale superconducting constriction,named as gate-controlled supercurrent(GCS),has raised great interest for fundamental and technological reasons.To gain a deeper understanding of this effect and develop superconducting technologies based on it,the material and physical parameters crucial for the GCS effect must be identified.Top-down fabrication protocols should also be optimized to increase device scalability,although studies suggest that top-down fabricated devices are more resilient to show a GCS.Here,we investigate gated superconducting nanobridges made with a top-down fabrication process from thin films of the noncentrosymmetric superconductor niobium rhenium with varying ratios of the constituents(NbRe).Unlike other devices previously reported and made with a top-down approach,our NbRe devices systematically exhibit a GCS effect when they were fabricated from NbRe thin films with small grain size and etched in specific conditions.These observations pave the way for the realization of top-down-made GCS devices with high scalability.Our results also imply that physical parameters like structural disorder and surface physical properties of the nanobridges,which can be in turn modified by the fabrication process,are crucial for a GCS observation,providing therefore also important insights into the physics underlying the GCS effect.展开更多
Oxygen is essential for plant growth and development.Hypoxia occurs in plants due to limited oxygen avail-abilityfollowing adverse environmental conditions as well inhypoxic niches in otherwisenormoxic environ-ments.H...Oxygen is essential for plant growth and development.Hypoxia occurs in plants due to limited oxygen avail-abilityfollowing adverse environmental conditions as well inhypoxic niches in otherwisenormoxic environ-ments.However,the existence and functional integration of spatiotemporal oxygen dynamics with plant development remains unknown.In animal systems dynamic fluctuations in oxygen availability are known as cyclic hypoxia.In this study,we demonstrate that cyclic fluctuations in internal oxygen levels occur in young emerging leaves of Arabidopsis plants.Cyclic hypoxia in plants is based on a mechanism requiring the ETHYLENE RESPONSE FACTORS type VII(ERFVII)that are central components of the oxygen-sensing machinery in plants.The ERFVll-dependent mechanism allows precise adjustment of leaf growth in response to carbon status and oxygen availability within plant cells.This study thus establishes a functional connection between internal spatiotemporal oxygen dynamics and developmental processes of plants.展开更多
Monodispersed ZnSnO3 microspheres are successfully prepared via a facile microwave-assisted method together with subsequently calcination treatment.Powder X-ray diffraction(PXRD)results indicate that the structure of ...Monodispersed ZnSnO3 microspheres are successfully prepared via a facile microwave-assisted method together with subsequently calcination treatment.Powder X-ray diffraction(PXRD)results indicate that the structure of the products shifted from crystalline to amorphous under high-tempe rature treatments.Field emission scanning electron microscope(FESEM)and the transmission electron microscope(TEM)observations demonstrate that the as-obtained products are composed of uniform microspheres with rough surfaces and the mean diameter is measured as-700 nm.Moreover,the morphology of ZnSnO3 microspheres can be well controlled by adjusting the ratio of Zn2+and Sn4+.The gas sensing properties of ZnSnO3 microspheres with different ratios of Zn2+/Sn4+are investigated.Our results indicate that the ZnSnO3 microspheres exhibit good selectivity and high sensitivity towards ethanol at the optimum working temperature of 230℃.When the sensor is exposed 50 ppm ethanol,the value of response is 47 and the response/recovery times are 11 s and 12 s,respectively.展开更多
Approximately 40% of USA coal originates in an ecologically sensitive area of semi-arid shortgrass prairie in Wyoming. Before a surface coal mine can begin operation in the USA, it must secure a mining permit and comp...Approximately 40% of USA coal originates in an ecologically sensitive area of semi-arid shortgrass prairie in Wyoming. Before a surface coal mine can begin operation in the USA, it must secure a mining permit and comply with regulations and performance standards under the USA Surface Mining Control and Reclamation Act （SMCRA）, other federal environmental acts, and state programs. The Wyoming Department of Environmental Quality （WDEQ）/Land Quality Division （LQD） administers Wyoming＇s coal regulatory program. The permit application and bonding process for the largest surface coal mine permit in the USA, North Antelope Rochelle Mine （NARM） located in short grassland prairie in the northeast Wyoming, is discussed. The permit application process begins with the collection of baseline environ- mental data that characterizes premining conditions of the permit area. The permit application includes adjudication information, baseline information, mine and operation plans, and reclamation plans. Fulfillment of permit commitments and requirements of rules and regulations are inspected monthly by the LQD＇ s representative in the field. Before a mine permit is issued, the mine operator must submit a reclamation bond to secure the performance of reclamation obligations that is later revised annually. In Wyoming, four reclamation bond release phases indicate the completion of various stages of the reclamatikon process. NARM＇s specific bond release verification cirteria, performance standards, and field verificatoins of bond release phases are discussed. The Bond Release Geodatabase （a GIS/GPS approach） was developed for this mine to monitor progress in meeting criteria and performance standards for incremental bond release. The Bond Release Geodatabase significantly reduces the time needed to track bond release progress, reach agreement between operator and regulator, and improve the state inspector＇s ability to assess reclamation adequacy and progress.展开更多
We demonstrate very large and uniform temperature gradients up to about 1 K every 100 nm, in an architecture which is compatible with the field-effect control of the nanostructure under test. The temperature gradients...We demonstrate very large and uniform temperature gradients up to about 1 K every 100 nm, in an architecture which is compatible with the field-effect control of the nanostructure under test. The temperature gradients demonstrated greatly exceed those typically obtainable with standard resistive heaters fabricated on top of the oxide layer. The nanoheating platform is demonstrated in the specific case of a short-nanowire device.展开更多
The controlled tailoring of the energy distribution in an electron system opens the way to interesting new physics and device concepts, as demonstrated by research on metallic nanodevices during recent years. Here we ...The controlled tailoring of the energy distribution in an electron system opens the way to interesting new physics and device concepts, as demonstrated by research on metallic nanodevices during recent years. Here we investigate how Josephson coupling in a superconductor-InAs nanowire junction can be tuned by means of hot-electron injection and we show that a complete suppression of superconductive effects can be achieved using a power as low as 100 pW. Nanowires offer a novel design freedom as they allow axial and radial heterostructures to be defined as well as control over doping profiles, which can be crucial in the development of devices--such as nanorefrigerators--where precisely controlled and predictable energy barriers are mandatory. Our work provides estimates for unknown key thermal and electrical parameters, such as the electron-phonon coupling, in our InAs nanostructures.展开更多
In this study, the effects of Radio Electric Asymmetric Conveyer(REAC), a non-invasive physical treatment, on neuroinflammatory responses in a mouse model of parkinsonism induced by intoxication with1-methyl-4-phenyl-...In this study, the effects of Radio Electric Asymmetric Conveyer(REAC), a non-invasive physical treatment, on neuroinflammatory responses in a mouse model of parkinsonism induced by intoxication with1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP),were investigated in vivo. We found that the REAC tissue optimization treatment specific for neuro-regenerative purposes(REAC TO-RGN-N) attenuated the inflammatory picture evoked by MPTP-induced nigro-striatal damage inmice, decreasing the levels of pro-inflammatory molecules and increasing anti-inflammatory mediators. Besides, there was a significant reduction of both astrocyte and microglial activation in MPTP-treated mice exposed to REAC TORGN-N. These results indicated that REAC TO-RGN-N treatment modulates the pro-inflammatory responses and reduces neuronal damage in MPTP-induced parkinsonism.展开更多
Resonators and the way they couple to external radiation rely on very different concepts if one considers devices belonging to the photonic and electronic worlds.The terahertz frequency range,however,provides intrigui...Resonators and the way they couple to external radiation rely on very different concepts if one considers devices belonging to the photonic and electronic worlds.The terahertz frequency range,however,provides intriguing possibilities for the development of hybrid technologies that merge ideas from both fields in novel functional designs.In this paper,we show that high-quality,subwavelength,whispering-gallery lasers can be combined to form a linear dipole antenna,which creates a very efficient,lowthreshold laser emission in a collimated beam pattern.For this purpose,we employ a terahertz quantum-cascade active region patterned into two 19-μm-radius microdisks coupled by a suspended metallic bridge,which simultaneously acts as an inductive antenna and produces the dipole symmetry of the lasing mode.Continuous-wave vertical emission is demonstrated at approximately 3.5 THz in a very regular,low-divergence(±10°)beam,with a high slope efficiency of at least 160 mWA^(−1) and a mere 6 mA of threshold current,which is ensured by the ultra-small resonator size(VRES/λ^(3)≈10^(−2)).The extremely low power consumption and the superior beam brightness make this concept very promising for the development of miniaturized and portable THz sources to be used in the field for imaging and sensing applications as well as for exploring novel optomechanical intracavity effects.展开更多
Chemical vapor deposition （CVD） is typically used for large-scale graphene synthesis for practical applications. However, the inferior electronic properties of CVD graphene are one of the key problems to be solved. ...Chemical vapor deposition （CVD） is typically used for large-scale graphene synthesis for practical applications. However, the inferior electronic properties of CVD graphene are one of the key problems to be solved. Therefore, we present a detailed study on the electronic properties of high-quality single-crystal monolayer graphene. The graphene is grown via CVD on copper, by using a cold-wall reactor, and then transferred to Si/SiO2. Our low-temperature magneto-transport data demonstrate that the characteristics of the single-crystal CVD graphene samples are superior to those of polycrystalline graphene and have a quality which is comparable to that of exfoliated graphene on Si/SiO2. The Dirac point in our best samples occurs at back-gate voltages lower than 10 V, and a maximum mobility of 11,000 cm2/（V.s） is attained. More than 12 flat and discernible half-integer quantum Hall plateaus occur under a high magnetic field on both the electron and hole sides of the Dirac point. At a low magnetic field, the magnetoresistance exhibits a weak localization peak. Using the theory of McCann et al., we obtain inelastic scattering lengths of 〉1 um, even at the charge neutrality point of the samples.展开更多
Engineering the local three-dimensional structure of metal sites has an important effect of maximizing the activity and selectivity of single-atom site catalysts.Here,we engineered a strain-assisted single Pt sites st...Engineering the local three-dimensional structure of metal sites has an important effect of maximizing the activity and selectivity of single-atom site catalysts.Here,we engineered a strain-assisted single Pt sites structure on a highly curved MoS_(2)surface to enhance its H_(2)S sensor property.By introducing N-methyl-2-pyrrolidone(NMP)as guiding molecules,a multilayer MoS_(2)structure with bending base planes was achieved.This bending behavior could inject not only uniform in-plane strain into the original inert MoS_(2)basal plane but also introduce sufficient accessible sites to anchor Pt monomers.Further experimental and theoretical results showed that the highcurvature MoS_(2)surface endowed 0.8%stretch strain onto the low-coordinated single Pt sites with a unique“tip”effect,which led to more accumulation of electrons around the Pt species,thereby accelerating the electric transfer process between H_(2)S and supports.The final catalyst delivered pronouncedly enhanced H_(2)S sensing response and response speed at room temperature.Our proposed strain-assisted strategy might create a new path to design highly active single-atom site catalysts for gas sensors.展开更多
This work reports a superhydrophobic divinylbenzene polymer with hierarchical porous structure as sensing material to modify the quartz crystal microbalance(QCM)to detect benzene,toluene,ethylbenzene,and xylene(BTEX)v...This work reports a superhydrophobic divinylbenzene polymer with hierarchical porous structure as sensing material to modify the quartz crystal microbalance(QCM)to detect benzene,toluene,ethylbenzene,and xylene(BTEX)vapor.Notably,sensing results toward toluene vapor in different relative humidities indicates that this superhydrophobic polymer has favorable toluene/water selective detection performance.Besides,the limit of detection toward toluene is lower than 1 ppm.展开更多
Random lasers are a class of devices in which feedback arises from multiple elastic scattering in a highly disordered structure,providing an almost ideal light source for artefact-free imaging due to achievable low sp...Random lasers are a class of devices in which feedback arises from multiple elastic scattering in a highly disordered structure,providing an almost ideal light source for artefact-free imaging due to achievable low spatial coherence.However,for many applications ranging from sensing and spectroscopy to speckle-free imaging,it is essential to have high-radiance sources operating in continuous-wave(CW).In this paper,we demonstrate CW operation of a random laser using an electrically pumped quantum-cascade laser gain medium in which a bi-dimensional(2D)random distribution of air holes is patterned into the top metal waveguide.We obtain a highly collimated vertical emission at ~3 THz,with a 430 GHz bandwidth,device operation up to 110 K,peak(pulsed)power of 21 mW,and CW emission of 1.7 mW.Furthermore,we show that an external cavity formed with a movable mirror can be used to tune a random laser,obtaining continuous frequency tuning over 11 GHz.展开更多
Objective: To observe the inhibition of intracranial glioma tumorigenesis by vascular endothelial growth factor (VEGF) antisense oligodeoxynucleotide (ODN) in rats. Methods: Totally 20 μ1 Hank's liquid containing...Objective: To observe the inhibition of intracranial glioma tumorigenesis by vascular endothelial growth factor (VEGF) antisense oligodeoxynucleotide (ODN) in rats. Methods: Totally 20 μ1 Hank's liquid containing 1×106 C6 glioma cells was seeded into rat right caudate putaraen in high-flow microinfusion with stereotactic technique. VEGF antisense ODN was simultaneously used with glioma cell. Each rat of the treated group Ⅰ and the treated group Ⅱ was treated with 1 000 μmol/L VEGF antisense ODN. Each rat of the treated group Ⅲ and the treated group Ⅳ was treated with 2 000 μmol/L VEGF antisense ODN. The experimental periods of the treated group Ⅰ , the treated group Ⅲ and the control group Ⅰ were 2 weeks, those of the treated group Ⅱ , the treated group Ⅳ and the control group Ⅱ were 3 weeks. Before sacrifice, MRI was performed on each rat. Tumor magnitude and pathologic examination were detected after samples were dissected. Results: The survival state of all treated rats was better, and that of the control rats was in severe danger. The tumor volumes of the treated group Ⅰ and the treated group Ⅱ were remarkably lessened. Tumor tissue could not be found macroscopically in the brain samples of the treated group Ⅲ and the treated group Ⅳ, but tumor nest could be found with microscopy. Tumors of the treated group I and the treated group Ⅱ had weak expressions of VEGF mRNA and VEGF, while normal brains and the samples of the treated group Ⅲ and the treated group Ⅳ had negative expressions, but tumors of the control groups had strong expressions. Conclusion: VEGF antisense ODN used early in situ can suppress angiogenesis and growth of rat intracranial glioma to retard tumorigenesis.展开更多
Peony pollen is a cheap and readily available biomass material with a relatively high protein content.In this work,it was employed as an N-rich precursor to prepare the nitrogen-doped porous carbon for supercapacitor ...Peony pollen is a cheap and readily available biomass material with a relatively high protein content.In this work,it was employed as an N-rich precursor to prepare the nitrogen-doped porous carbon for supercapacitor application.The porous carbon microspheres were prepared through a hydrothermal method and subsequent carbonization process.Notably,ammonium borofruoride and potassium hydroxide were employed respectively as an etchant and an activator to modify the porosity of the materials.The as prepared ANPPCs-700 has a super high BET specific surface area of 824.69 m^2/g.The microstructure,chemical state and electrochemical properties of the product were investigated in detail.The prepared nitrogen-doped carbon microspheres exhibits excellent specific capacity of 209 F/g at a current density of lA/g and remained 92.5%of the initial capacitance after 5000 deep cycles at 5 A/g.展开更多
Porous polyaniline (PANI) was prepared through an efficient and costeffective method by polymerization of aniline in the NaCl solution at room temperature. The resulting PANI provided large surface area due to its hig...Porous polyaniline (PANI) was prepared through an efficient and costeffective method by polymerization of aniline in the NaCl solution at room temperature. The resulting PANI provided large surface area due to its highly porous structure and the intercrossed nanorod, resulting in good electrochemical performance. The porous PANI electrodes showed a high specific capacitance of 480 F·g^-1, 3 times greater than that of PANI without using the NaCl solution. We also make chemically crosslinked hydrogel film for hydrogel polymer electrolyte as well as the flexible supercapacitors (SCs) with PANI. The specific capacitance of the device was 234 F·g^-1 at the current density of 1 A·g^-1. The energy density of the device could reach as high as 75 W·h·kg^-1 while the power density was 0.5 kW·kg^-1, indicating that PANI be a promising material in flexible SCs.展开更多
基金supported by the National Key R&D Program of China (2017YFA0208300)the National Natural Science Foundation of China (21522107, 21671180, 21521091, 21390393, U1463202, and 21522305)
文摘Tremendous efforts have been devoted to explore energy-efficient strategies of ammonia synthesis to replace Haber-Bosch process which accounts for 1.4% of the annual energy consumption. In this study, atomically dispersed Au_1 catalyst is synthesized and applied in electrochemical synthesis of ammonia under ambient conditions. A high NH＋4 Faradaic efficiency of 11.1 % achieved by our Au_1 catalyst surpasses most of reported catalysts under comparable conditions. Benefiting from efficient atom utilization, an NH＋4 yield rate of 1,305 μg h-1 mg-1Au has been reached, which is roughly 22.5 times as high as that by sup- ported Au nanoparticles. We also demonstrate that by employing our Au_1 catalyst, NH＋4 can be electro- chemically produced directly from N_2 and H_2 with an energy utilization rate of 4.02 mmol kJ-1. Our study provides a possibility of replacing the Haber-Bosch process with environmentally benign and energy-efficient electrochemical strategies.
基金This work was supported by the National Natural Science Foundation of China(62271299)Shanghai Sailing Program(22YF1413400).Shanghai Engineering Research Center for We thank the Integrated Circuits and Advanced Display Materials.
文摘Reasonably constructing an atomic interface is pronouncedly essential for surface-related gas-sensing reaction.Herein,we present an ingen-ious feedback-regulation system by changing the interactional mode between single Pt atoms and adjacent S species for high-efficiency SO_(2)sensing.We found that the single Pt sites on the MoS_(2)surface can induce easier volatiliza-tion of adjacent S species to activate the whole inert S plane.Reversely,the activated S species can provide a feedback role in tailoring the antibonding-orbital electronic occupancy state of Pt atoms,thus creating a combined system involving S vacancy-assisted single Pt sites(Pt-Vs)to synergistically improve the adsorption ability of SO_(2)gas molecules.Further-more,in situ Raman,ex situ X-ray photoelectron spectroscopy testing and density functional theory analysis demonstrate the intact feedback-regulation system can expand the electron transfer path from single Pt sites to whole Pt-MoS_(2)supports in SO_(2)gas atmosphere.Equipped with wireless-sensing modules,the final Pt1-MoS_(2)-def sensors array can further realize real-time monitoring of SO_(2)levels and cloud-data storage for plant growth.Such a fundamental understanding of the intrinsic link between atomic interface and sensing mechanism is thus expected to broaden the rational design of highly effective gas sensors.
基金supported by the Ministry of Science and Technology of China(No.2021YFA1500404)the National Natural Science Foundation of China(Nos.92261105 and 22221003)+1 种基金USTC Research Funds of the Double First-Class Initiative(No.YD9990002022)the Shanghai Sailing Program(No.22YF1413400).
文摘Printing techniques hold great potential in the manufacture of electronics such as sensors,micro-supercapacitors,and flexible electronics.However,developing large-scale functional conductive inks with appropriate rheological properties and active components still remains a challenge.Herein,through optimizing the formulations of ink,iron single sites supported N-doped carbon black(Fe_(1)-NC)inks can serve as both conductive electrodes and high-reactive catalysts to realize convenient glucose detection,which pronouncedly reduces the dosage of enzyme and simplifies the sensors preparation.In detail,utilizing in-situ pyrolysis method,Fe_(1)-NC single-atom catalysts(SACs)are prepared in bulk(dekagram-level).The batched Fe_(1)-NC SACs materials can be uniformly mixed with modulated ink to realize the screen printing with high resolution and uniformity.Also,the whole scalable preparation and ink-functional process can be extended to various metals(including Co,Ni,Cu,and Mn).The introduction of highly active Fe_(1)-NC sites reduces the amount of enzyme used in glucose detection by at least 50%,contributing to the cost reduction of sensors.The strategy in harnessing the SACs onto the carbon inks thus provides a broad prospect for the low-cost and large-scale printing of sensitive sensing devices.
基金the European Union’s Horizon 2020 Research and Innovation Program under Grant Agreement No.964398(SuperGate)the US ONR(Nos.N00014-21-1-2879,N00014-20-1-2442,and N00014-23-1-2866).
文摘The application of a gate voltage to control the superconducting current flowing through a nanoscale superconducting constriction,named as gate-controlled supercurrent(GCS),has raised great interest for fundamental and technological reasons.To gain a deeper understanding of this effect and develop superconducting technologies based on it,the material and physical parameters crucial for the GCS effect must be identified.Top-down fabrication protocols should also be optimized to increase device scalability,although studies suggest that top-down fabricated devices are more resilient to show a GCS.Here,we investigate gated superconducting nanobridges made with a top-down fabrication process from thin films of the noncentrosymmetric superconductor niobium rhenium with varying ratios of the constituents(NbRe).Unlike other devices previously reported and made with a top-down approach,our NbRe devices systematically exhibit a GCS effect when they were fabricated from NbRe thin films with small grain size and etched in specific conditions.These observations pave the way for the realization of top-down-made GCS devices with high scalability.Our results also imply that physical parameters like structural disorder and surface physical properties of the nanobridges,which can be in turn modified by the fabrication process,are crucial for a GCS observation,providing therefore also important insights into the physics underlying the GCS effect.
文摘Oxygen is essential for plant growth and development.Hypoxia occurs in plants due to limited oxygen avail-abilityfollowing adverse environmental conditions as well inhypoxic niches in otherwisenormoxic environ-ments.However,the existence and functional integration of spatiotemporal oxygen dynamics with plant development remains unknown.In animal systems dynamic fluctuations in oxygen availability are known as cyclic hypoxia.In this study,we demonstrate that cyclic fluctuations in internal oxygen levels occur in young emerging leaves of Arabidopsis plants.Cyclic hypoxia in plants is based on a mechanism requiring the ETHYLENE RESPONSE FACTORS type VII(ERFVII)that are central components of the oxygen-sensing machinery in plants.The ERFVll-dependent mechanism allows precise adjustment of leaf growth in response to carbon status and oxygen availability within plant cells.This study thus establishes a functional connection between internal spatiotemporal oxygen dynamics and developmental processes of plants.
基金supported by National Nature Science Foundation of China(Nos.61671284 and U1704255)。
文摘Monodispersed ZnSnO3 microspheres are successfully prepared via a facile microwave-assisted method together with subsequently calcination treatment.Powder X-ray diffraction(PXRD)results indicate that the structure of the products shifted from crystalline to amorphous under high-tempe rature treatments.Field emission scanning electron microscope(FESEM)and the transmission electron microscope(TEM)observations demonstrate that the as-obtained products are composed of uniform microspheres with rough surfaces and the mean diameter is measured as-700 nm.Moreover,the morphology of ZnSnO3 microspheres can be well controlled by adjusting the ratio of Zn2+and Sn4+.The gas sensing properties of ZnSnO3 microspheres with different ratios of Zn2+/Sn4+are investigated.Our results indicate that the ZnSnO3 microspheres exhibit good selectivity and high sensitivity towards ethanol at the optimum working temperature of 230℃.When the sensor is exposed 50 ppm ethanol,the value of response is 47 and the response/recovery times are 11 s and 12 s,respectively.
文摘Approximately 40% of USA coal originates in an ecologically sensitive area of semi-arid shortgrass prairie in Wyoming. Before a surface coal mine can begin operation in the USA, it must secure a mining permit and comply with regulations and performance standards under the USA Surface Mining Control and Reclamation Act （SMCRA）, other federal environmental acts, and state programs. The Wyoming Department of Environmental Quality （WDEQ）/Land Quality Division （LQD） administers Wyoming＇s coal regulatory program. The permit application and bonding process for the largest surface coal mine permit in the USA, North Antelope Rochelle Mine （NARM） located in short grassland prairie in the northeast Wyoming, is discussed. The permit application process begins with the collection of baseline environ- mental data that characterizes premining conditions of the permit area. The permit application includes adjudication information, baseline information, mine and operation plans, and reclamation plans. Fulfillment of permit commitments and requirements of rules and regulations are inspected monthly by the LQD＇ s representative in the field. Before a mine permit is issued, the mine operator must submit a reclamation bond to secure the performance of reclamation obligations that is later revised annually. In Wyoming, four reclamation bond release phases indicate the completion of various stages of the reclamatikon process. NARM＇s specific bond release verification cirteria, performance standards, and field verificatoins of bond release phases are discussed. The Bond Release Geodatabase （a GIS/GPS approach） was developed for this mine to monitor progress in meeting criteria and performance standards for incremental bond release. The Bond Release Geodatabase significantly reduces the time needed to track bond release progress, reach agreement between operator and regulator, and improve the state inspector＇s ability to assess reclamation adequacy and progress.
文摘We demonstrate very large and uniform temperature gradients up to about 1 K every 100 nm, in an architecture which is compatible with the field-effect control of the nanostructure under test. The temperature gradients demonstrated greatly exceed those typically obtainable with standard resistive heaters fabricated on top of the oxide layer. The nanoheating platform is demonstrated in the specific case of a short-nanowire device.
文摘The controlled tailoring of the energy distribution in an electron system opens the way to interesting new physics and device concepts, as demonstrated by research on metallic nanodevices during recent years. Here we investigate how Josephson coupling in a superconductor-InAs nanowire junction can be tuned by means of hot-electron injection and we show that a complete suppression of superconductive effects can be achieved using a power as low as 100 pW. Nanowires offer a novel design freedom as they allow axial and radial heterostructures to be defined as well as control over doping profiles, which can be crucial in the development of devices--such as nanorefrigerators--where precisely controlled and predictable energy barriers are mandatory. Our work provides estimates for unknown key thermal and electrical parameters, such as the electron-phonon coupling, in our InAs nanostructures.
基金supported by a Fondazione Umberto Veronesi 2011 grant to RRa grant from the University of Bari(Fondi di Ateneo 2014)a grant from the University of Salento(Fondi di Ateneo 2014)
文摘In this study, the effects of Radio Electric Asymmetric Conveyer(REAC), a non-invasive physical treatment, on neuroinflammatory responses in a mouse model of parkinsonism induced by intoxication with1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP),were investigated in vivo. We found that the REAC tissue optimization treatment specific for neuro-regenerative purposes(REAC TO-RGN-N) attenuated the inflammatory picture evoked by MPTP-induced nigro-striatal damage inmice, decreasing the levels of pro-inflammatory molecules and increasing anti-inflammatory mediators. Besides, there was a significant reduction of both astrocyte and microglial activation in MPTP-treated mice exposed to REAC TORGN-N. These results indicated that REAC TO-RGN-N treatment modulates the pro-inflammatory responses and reduces neuronal damage in MPTP-induced parkinsonism.
文摘Resonators and the way they couple to external radiation rely on very different concepts if one considers devices belonging to the photonic and electronic worlds.The terahertz frequency range,however,provides intriguing possibilities for the development of hybrid technologies that merge ideas from both fields in novel functional designs.In this paper,we show that high-quality,subwavelength,whispering-gallery lasers can be combined to form a linear dipole antenna,which creates a very efficient,lowthreshold laser emission in a collimated beam pattern.For this purpose,we employ a terahertz quantum-cascade active region patterned into two 19-μm-radius microdisks coupled by a suspended metallic bridge,which simultaneously acts as an inductive antenna and produces the dipole symmetry of the lasing mode.Continuous-wave vertical emission is demonstrated at approximately 3.5 THz in a very regular,low-divergence(±10°)beam,with a high slope efficiency of at least 160 mWA^(−1) and a mere 6 mA of threshold current,which is ensured by the ultra-small resonator size(VRES/λ^(3)≈10^(−2)).The extremely low power consumption and the superior beam brightness make this concept very promising for the development of miniaturized and portable THz sources to be used in the field for imaging and sensing applications as well as for exploring novel optomechanical intracavity effects.
文摘Chemical vapor deposition （CVD） is typically used for large-scale graphene synthesis for practical applications. However, the inferior electronic properties of CVD graphene are one of the key problems to be solved. Therefore, we present a detailed study on the electronic properties of high-quality single-crystal monolayer graphene. The graphene is grown via CVD on copper, by using a cold-wall reactor, and then transferred to Si/SiO2. Our low-temperature magneto-transport data demonstrate that the characteristics of the single-crystal CVD graphene samples are superior to those of polycrystalline graphene and have a quality which is comparable to that of exfoliated graphene on Si/SiO2. The Dirac point in our best samples occurs at back-gate voltages lower than 10 V, and a maximum mobility of 11,000 cm2/（V.s） is attained. More than 12 flat and discernible half-integer quantum Hall plateaus occur under a high magnetic field on both the electron and hole sides of the Dirac point. At a low magnetic field, the magnetoresistance exhibits a weak localization peak. Using the theory of McCann et al., we obtain inelastic scattering lengths of 〉1 um, even at the charge neutrality point of the samples.
基金This work was supported by the China Ministry of Science and Technology(grant no.2020YFA0710200)National Key R&D Program of China 2017YFA(grant nos.0208300 and 0700104)+2 种基金the National Natural Science Foundation of China(grant no.21671180)the Dalian National Laboratory for Clean Energy(DNL)Cooperation Fund,CAS(grant no.DNL201918)the Fundamental Research Funds for the Central Universities(grant nos.WK2060120004,WK2060000021,WK2060000025,and KY2060000180).
文摘Engineering the local three-dimensional structure of metal sites has an important effect of maximizing the activity and selectivity of single-atom site catalysts.Here,we engineered a strain-assisted single Pt sites structure on a highly curved MoS_(2)surface to enhance its H_(2)S sensor property.By introducing N-methyl-2-pyrrolidone(NMP)as guiding molecules,a multilayer MoS_(2)structure with bending base planes was achieved.This bending behavior could inject not only uniform in-plane strain into the original inert MoS_(2)basal plane but also introduce sufficient accessible sites to anchor Pt monomers.Further experimental and theoretical results showed that the highcurvature MoS_(2)surface endowed 0.8%stretch strain onto the low-coordinated single Pt sites with a unique“tip”effect,which led to more accumulation of electrons around the Pt species,thereby accelerating the electric transfer process between H_(2)S and supports.The final catalyst delivered pronouncedly enhanced H_(2)S sensing response and response speed at room temperature.Our proposed strain-assisted strategy might create a new path to design highly active single-atom site catalysts for gas sensors.
基金supported by National Natural Science Foundation of China(No.61527818)the financial support from Zhejiang Sci-Tech University(ZSTU,No.19012393-Y)。
文摘This work reports a superhydrophobic divinylbenzene polymer with hierarchical porous structure as sensing material to modify the quartz crystal microbalance(QCM)to detect benzene,toluene,ethylbenzene,and xylene(BTEX)vapor.Notably,sensing results toward toluene vapor in different relative humidities indicates that this superhydrophobic polymer has favorable toluene/water selective detection performance.Besides,the limit of detection toward toluene is lower than 1 ppm.
基金partly supported by the European Union ERC Consolidator Grant SPRINT(681379)the EPSRC Programme Grant‘HyperTerahertz’(EP/P021859/1)the support of the Royal Society and the Wolfson Foundation.
文摘Random lasers are a class of devices in which feedback arises from multiple elastic scattering in a highly disordered structure,providing an almost ideal light source for artefact-free imaging due to achievable low spatial coherence.However,for many applications ranging from sensing and spectroscopy to speckle-free imaging,it is essential to have high-radiance sources operating in continuous-wave(CW).In this paper,we demonstrate CW operation of a random laser using an electrically pumped quantum-cascade laser gain medium in which a bi-dimensional(2D)random distribution of air holes is patterned into the top metal waveguide.We obtain a highly collimated vertical emission at ~3 THz,with a 430 GHz bandwidth,device operation up to 110 K,peak(pulsed)power of 21 mW,and CW emission of 1.7 mW.Furthermore,we show that an external cavity formed with a movable mirror can be used to tune a random laser,obtaining continuous frequency tuning over 11 GHz.
文摘Objective: To observe the inhibition of intracranial glioma tumorigenesis by vascular endothelial growth factor (VEGF) antisense oligodeoxynucleotide (ODN) in rats. Methods: Totally 20 μ1 Hank's liquid containing 1×106 C6 glioma cells was seeded into rat right caudate putaraen in high-flow microinfusion with stereotactic technique. VEGF antisense ODN was simultaneously used with glioma cell. Each rat of the treated group Ⅰ and the treated group Ⅱ was treated with 1 000 μmol/L VEGF antisense ODN. Each rat of the treated group Ⅲ and the treated group Ⅳ was treated with 2 000 μmol/L VEGF antisense ODN. The experimental periods of the treated group Ⅰ , the treated group Ⅲ and the control group Ⅰ were 2 weeks, those of the treated group Ⅱ , the treated group Ⅳ and the control group Ⅱ were 3 weeks. Before sacrifice, MRI was performed on each rat. Tumor magnitude and pathologic examination were detected after samples were dissected. Results: The survival state of all treated rats was better, and that of the control rats was in severe danger. The tumor volumes of the treated group Ⅰ and the treated group Ⅱ were remarkably lessened. Tumor tissue could not be found macroscopically in the brain samples of the treated group Ⅲ and the treated group Ⅳ, but tumor nest could be found with microscopy. Tumors of the treated group I and the treated group Ⅱ had weak expressions of VEGF mRNA and VEGF, while normal brains and the samples of the treated group Ⅲ and the treated group Ⅳ had negative expressions, but tumors of the control groups had strong expressions. Conclusion: VEGF antisense ODN used early in situ can suppress angiogenesis and growth of rat intracranial glioma to retard tumorigenesis.
基金financial supports from the National Key Research and Development Program of China(Nos.2017YFB0102200,2017YFB0102900)。
文摘Peony pollen is a cheap and readily available biomass material with a relatively high protein content.In this work,it was employed as an N-rich precursor to prepare the nitrogen-doped porous carbon for supercapacitor application.The porous carbon microspheres were prepared through a hydrothermal method and subsequent carbonization process.Notably,ammonium borofruoride and potassium hydroxide were employed respectively as an etchant and an activator to modify the porosity of the materials.The as prepared ANPPCs-700 has a super high BET specific surface area of 824.69 m^2/g.The microstructure,chemical state and electrochemical properties of the product were investigated in detail.The prepared nitrogen-doped carbon microspheres exhibits excellent specific capacity of 209 F/g at a current density of lA/g and remained 92.5%of the initial capacitance after 5000 deep cycles at 5 A/g.
文摘Porous polyaniline (PANI) was prepared through an efficient and costeffective method by polymerization of aniline in the NaCl solution at room temperature. The resulting PANI provided large surface area due to its highly porous structure and the intercrossed nanorod, resulting in good electrochemical performance. The porous PANI electrodes showed a high specific capacitance of 480 F·g^-1, 3 times greater than that of PANI without using the NaCl solution. We also make chemically crosslinked hydrogel film for hydrogel polymer electrolyte as well as the flexible supercapacitors (SCs) with PANI. The specific capacitance of the device was 234 F·g^-1 at the current density of 1 A·g^-1. The energy density of the device could reach as high as 75 W·h·kg^-1 while the power density was 0.5 kW·kg^-1, indicating that PANI be a promising material in flexible SCs.
