In vivo imaging in the deep near-infrared(NIR)spectral region,that is,beyond 800 nm,has become popular due to its penetration depth.While imaging of the neutral medium/tissue has been repeatedly showcased,imaging of t...In vivo imaging in the deep near-infrared(NIR)spectral region,that is,beyond 800 nm,has become popular due to its penetration depth.While imaging of the neutral medium/tissue has been repeatedly showcased,imaging of the high-acidic medium remains challenging partly because of the high-lying HOMO orbital and hence a high pKa of the electron-donating group of the NIR fluorophores.We devised a novel electron-donating group(D6)with which we further synthesized ECJ.ECJ exhibits an absorption wavelength beyond 900 nm and is fluorescent.Its pKa was found to be lower than zero,rendering it suitable for bioimaging of a highly-acidic medium.Its potential for practical applications was showcased in proof-of-concept in vivo imaging with a mouse model.展开更多
A pair of asymmetric rigid carbazole-benzonitrile-based emitters were synthesized by strategically alternating donor and acceptor groups along the molecular edges.The spin-flip process is accelerated by both the forma...A pair of asymmetric rigid carbazole-benzonitrile-based emitters were synthesized by strategically alternating donor and acceptor groups along the molecular edges.The spin-flip process is accelerated by both the formation of localized and delocalized charge transfer states due to linearly positioned donors and strong spin-orbital coupling between different excitation feature of the lowest singlet and triplet excited states.This molecular architecture results in a remarkable short delayed lifespan of around 100 ns.The application of the two emitters in organic light-emitting diodes(OLEDs)achieves the highest external quantum efficiencies of 13.0%for the green emitter and 9.1%for the sky-blue emitter.Impressively,these devices maintain their high efficiency even at high luminance levels.The sustained efficiency is ascribed to the effective suppression of exciton quenching by substantially shortening delayed lifespan.These findings underscore the practical utility of the molecular design strategy that incorporates alternate donor and acceptor groups at the molecular periphery for shortening delayed fluorescence lifetime,and hold great promise for the development of high-performance OLEDs.展开更多
Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy...Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy physics in the last two decades,a new-generation Tau-Charm factory,called the Super Tau-Charm Facility(STCF),has been actively promoted by the particle physics community in China.STCF has the potential to address fundamental questions such as the essence of color confinement and the matter-antimatter asymmetry within the next decades.The main design goals of the STCF are a center-of-mass energy ranging from 2 to 7 GeV and a luminosity surpassing 5×10^(34)cm^(−2)s^(−1)that is optimized at a center-of-mass energy of 4 GeV,which is approximately 50 times that of the currently operating Tau-Charm factory-BEPCII.The STCF accelerator has two main parts:a double-ring collider with a crab-waist collision scheme and an injector that provides top-up injections for both electron and positron beams.As a typical third-generation electron-positron circular collider,the STCF accelerator faces many challenges in both accelerator physics and technology.In this paper,the conceptual design of the STCF accelerator complex is presented,including the ongoing efforts and plans for technological research and develop-ment,as well as the required infrastructure.The STCF project aims to secure support from the Chinese central government for its construction during the 15th Five-Year Plan(2026-2030).展开更多
Electronic structures, which play a key role in determining electrical and optical properties of π-conjugated organic materials, have attracted tremendous interest. Efficient thermoelectric (TE) conversion of organic...Electronic structures, which play a key role in determining electrical and optical properties of π-conjugated organic materials, have attracted tremendous interest. Efficient thermoelectric (TE) conversion of organic materials has rigorous requirements on electronic structures. Recently, the rational design and precise modulation of electronic structures have exhibited great potential in exploring state-of-the-art organic TE materials. This review focuses on the regulation of electronic structures of organic materials toward efficient TE conversion. First, we present the basic knowledge regarding electronic structures and the requirements for efficient TE conversion of organic materials, followed by a brief introduction of commonly used methods for electronic structure characterization. Next, we highlight the key strategies of electronic structure engineering for high-performance organic TE materials. Finally, an overview of the electronic structure engineering of organic TE materials, along with current challenges and future research directions, are provided.展开更多
High-brightness electron beams are required to drive LINAC-based free-electron lasers(FELs)and storage-ring-based synchrotron radiation light sources.The bunch charge and RMS bunch length at the exit of the LINAC play...High-brightness electron beams are required to drive LINAC-based free-electron lasers(FELs)and storage-ring-based synchrotron radiation light sources.The bunch charge and RMS bunch length at the exit of the LINAC play a crucial role in the peak current;the minimum transverse emittance is mainly determined by the injector of the LINAC.Thus,a photoin-jector with a high bunch charge and low emittance that can simultaneously provide high-quality beams for 4th generation synchrotron radiation sources and FELs is desirable.The design of a 1.6-cell S-band 2998-MHz RF gun and beam dynamics optimization of a relevant beamline are presented in this paper.Beam dynamics simulations were performed by combining ASTRA and the multi-objective genetic algorithm NSGA II.The effects of the laser pulse shape,half-cell length of the RF gun,and RF parameters on the output beam quality were analyzed and compared.The normalized transverse emittance was optimized to be as low as 0.65 and 0.92 mm·mrad when the bunch charge was as high as 1 and 2 nC,respectively.Finally,the beam stability properties of the photoinjector,considering misalignment and RF jitter,were simulated and analyzed.展开更多
Surface charge transfer doping of graphene plays an important role in graphene-based electronics due to its simplicity,high doping efficiency,and easy-controllability.Here,we demonstrate the effective surface charge t...Surface charge transfer doping of graphene plays an important role in graphene-based electronics due to its simplicity,high doping efficiency,and easy-controllability.Here,we demonstrate the effective surface charge transfer hole doping of graphene by using a strong p-type molecular dopant hexacyanotrimethylene-cyclopropane (CN6-CP).The CN6-CP exhibits a very high intrinsic work function of 6.37 e V,which facilitates remarkable electron transfer from graphene to CN6-CP as revealed by in situ photoelectron spectroscopy investigations.Consequently,hole accumulation appears in the graphene layer at the direct contact with CN6-CP.As evidenced by Hall effect measurements,the areal hole density of graphene significantly increased from 8.3×10^(12)cm^(-2) to 2.21×10^(13)cm^(-2) upon 6 nm CN6-CP evaporation.The CN6-CP acceptor with strong p-doping effect has great implications for both graphene-based and organic electronics.展开更多
Molecular structure of organic semiconductor plays a critical role in determining the performance and functionality of organic electronic devices,by optimizing the electrical,optical and physicochemical properties.Sub...Molecular structure of organic semiconductor plays a critical role in determining the performance and functionality of organic electronic devices,by optimizing the electrical,optical and physicochemical properties.Substituted alkyl chains are fundamental units in tailering the solubility and assemblability,among which the asymmetric properties have been reported as key element for controlling the packing motifs and intrinsic charge transport.Here,we expanded the scope of molecular asymmetry dependent sensing features based on a new series of naphthalene diimides(NDI)-based derivatives substituted with a same branching alkyl chain but various linear-shaped alkyl chains(Cn-).A clear molecular stacking change,from head-to-head bilayer to head-to-tail monolayer packing model,is observed based on the features of anisotropic molecular interactions with the change in the chain length.Most importantly,a unique LUMO level shift of 0.17 eV is validated for NDI-PhC4,providing a record sensitivity up to 150%to 0.01 ppb ammonia,due to the desired molecular reactivity and device amplification properties.These results indicate that asymmetric side-chain engineering opens a route for breath healthcare.展开更多
Since the discovery of the Nernst effect in 19th century,it has been an important transverse thermoelectric charge transport phenomenon in solid states.Conjugated polymers have recently attracted great attention as pr...Since the discovery of the Nernst effect in 19th century,it has been an important transverse thermoelectric charge transport phenomenon in solid states.Conjugated polymers have recently attracted great attention as promising optoelectronic materials.However,the Nernst effect is yet to be explored for conducting polymers.Here,we report the first theoretical investigations of the Nernst effect in doped conducting polymers by first-principles calculations under the frame work of Fermi-liquid theory.Specifically,the Nernst coefficients of PBTTT are found to be ranging from 0.0029 to 0.039μV K^(-1)T^(-1).They are monotonically decreased with the doping level due to both much enhanced Fermi energy and the decreased charge mobility at high doping level.Our theoretical findings not only enhance our fundamental understanding of the doping mechanism that controls the charge transport properties of conducting polymers,but more importantly,they also offer initial predictions of the transverse thermoelectric conversion capability of conducting polymers.These predictions are crucial for the development of future flexible thermoelectric applications based on the Nernst effect.展开更多
Two-dimensional(2D)atomically thin quantum dots(QDs)possess extraordinary electrical and optical properties.However,fabricating high quality 2D QDs via a universal and reliable technique remains a challenge.Here,we re...Two-dimensional(2D)atomically thin quantum dots(QDs)possess extraordinary electrical and optical properties.However,fabricating high quality 2D QDs via a universal and reliable technique remains a challenge.Here,we report a simple strategy to prepare high quality,monolayer single crystal 2D QDs via ultrathin cutting 2D bulk single crystals by ultramicrotome,followed by an exfoliation process.The as-prepared 2D QDs have pristine surface,high quality,high monolayer yield and high photoluminescence quantum yield(the highest photoluminescence quantum yield of WS2 is18%),which can be used as promising,low toxic,biocompatible,and good cell-permeability fluorescent labeling agents for in vitro imaging.展开更多
Photogating and electrical gating are key physical mechanisms in organic phototransistors(OPTs).However,most OPTs are based on thick and polycrystalline films,which leads to substantially low efficiency of both photog...Photogating and electrical gating are key physical mechanisms in organic phototransistors(OPTs).However,most OPTs are based on thick and polycrystalline films,which leads to substantially low efficiency of both photogating and electrical gating and thus reduced photoresponse.Herein,high-performance OPTs based on few-layered organic single-crystalline heterojunctions are proposed and the obstacle of thick and polycrystalline films for photodetection is overcome.Because of the molecular scale thickness of the type I organic single-crystalline heterojunctions in OPTs,both photogating and electrical gating are highly efficient.By synergy of efficient photogating and electrical gating,key figures of merit of OPTs reach the highest among those based on planar heterojunctions so far as we know.The production of few-layered organic single-crystalline heterojunctions will provide a new type of advanced materials for various applications.展开更多
Conjugated polymers are attracting increased attention as thermoelectric(TE)materials for energy harvesting applications in low-temperature regimes.However,in many doped ambipolar polymers,the simultaneous transport o...Conjugated polymers are attracting increased attention as thermoelectric(TE)materials for energy harvesting applications in low-temperature regimes.However,in many doped ambipolar polymers,the simultaneous transport of both holes and electrons under temperature gradients leads to an offset in thermopower(S),which suppresses TE performance and complicates intrinsic understanding of bipolar TE conversion.Herein,we quantitatively investigate the p-n polarity transition in FeCl_(3)-doped bipolar PDPP4T films by measuring the magneto-thermoelectric Nernst effect,combined with Hall and Seebeck effect analyses.Notably,behind the S=0 point,we observe a significant thermopower offset originating from the balancing contributions of electrons and holes.This countervailing thermopower value is extracted to reach 400μV K^(-1),which could ideally produce an estimated maximum unipolar ZT of 0.24 at 175 K,due to rising polaron states and reduced carrier concentration.Our findings reveal the extraordinary hidden unipolar TE performance achievable in doped bipolar polymer towards ultra-low-temperatures thermoelectric.展开更多
The spinterface formed between ferromagnetic(FM)electrode and organic materials is vital for performance optimization in organic spin valve(OSV).Half-metallic Fe_(3)O_(4)with drastic change in structure,conductivity a...The spinterface formed between ferromagnetic(FM)electrode and organic materials is vital for performance optimization in organic spin valve(OSV).Half-metallic Fe_(3)O_(4)with drastic change in structure,conductivity and magnetic property near Verwey transition can serve as an intrinsic spinterface regulator.However,such modulating effect of Fe_(3)O_(4)in OSV has not been comprehensively investigated,especially below the Verwey transition temperature(Tv).Here,we highlight the important role of Fe_(3)O_(4)electrode in reliable-working and controllable Fe_(3)O_(4)/P3HT/Co polymer spin valves by investigating the magnetoresistance(MR)above and below 7V.In order to distinguish between different contributions to charge transport and related MR responses,the systematic electronic and magnetic characterizations were carried out in full temperature range.Particularly,the first-order metal-insulator transition in Fe_(3)O_(4)has a dramatic effect on the MR enhancement of polymer spin valves at 7V.Moreover,both the conducting mode transformation and MR line shape modulation could be accomplished across 7V.This research renders unique scenario to multimodal storage by external thermodynamic parameters,and further reveals the importance of spin-dependent interfacial modification in polymer spin valves.展开更多
Carbon films prepared from pyrolyzation of spin-casted polyacrylonitrile(PAN)thin films display high electrical conductivity(〉600 S/cm,at 1000℃carbonization),low sheet resistance(about 100 Y2/square at the PAN film ...Carbon films prepared from pyrolyzation of spin-casted polyacrylonitrile(PAN)thin films display high electrical conductivity(〉600 S/cm,at 1000℃carbonization),low sheet resistance(about 100 Y2/square at the PAN film thickness of 70 nm)and partial transmittance.These pyrolyzed PAN(PPAN)films were patterned as bottom electrodes by photolithography,and utilized as drain and source electrodes to fabricate organic field-effect transistor(OFET)devices with a p-type semiconductor(P3HT)and an n-type semiconductor(DPP-containing quinoidal small molecule)through a spin-coating procedure.The results showed that the devices with the PAN electrodes exhibited almost the same excellent performance without any further modification compared to those devices with traditional Au electrodes.Since these PPAN films had the advantages of low-cost,high performance,easier for large-area fabrication,thermal and chemical stability,it should be a promising electrode material for organic electrodes.展开更多
Developing efficient and promising tenderising techniques for postmortem meat is a heavily researched topic among meat scientists as consumers are willing to pay more for guaranteed tender meat.However,emerging tender...Developing efficient and promising tenderising techniques for postmortem meat is a heavily researched topic among meat scientists as consumers are willing to pay more for guaranteed tender meat.However,emerging tenderising techniques are not broadly used in the meat industry and,to some degree,are controversial due to lack of theoretical support.Thus,understanding the mechanisms involved in postmortem tenderisation is essential.This article first provides an overview of the relationship of ageing tenderisation and calpain system,as well as proteomics applied to identify protein biomarkers characterizing tenderness.In general,the ageing tenderisation is mediated by multiple biochemical activities,and it can exhibit better palatability and commercial benefit by combining other interventions.The calpain system plays a key role in ageing tenderisation functions by rupturing myofibrils and regulating proteolysis,glycolysis,apoptosis and metabolic modification.Additionally,tenderising techniques from different aspects including exogenous enzymes,chemistry,physics and the combined methods are discussed in depth.Particularly,innovation of home cooking could be recommended to prepare relatively tender meat due to its convenience and ease of operation by consumers.Furthermore,the combined interventions provide better performance in controlled tenderness.Finally,future trends in developing new tenderising techniques,and applied consideration in the meat processing industry are proposed in order to improve meat quality with higher economical value.展开更多
Thermoelectric(TE)materials can realize mutual energy conversion between heat and electricity and are applied broadly in energy harvesting,local cooling or heating,and thermal sensing[1].TE devices are crucial to solv...Thermoelectric(TE)materials can realize mutual energy conversion between heat and electricity and are applied broadly in energy harvesting,local cooling or heating,and thermal sensing[1].TE devices are crucial to solve the global energy crisis with renewable energy resources.Currently,most of the research works are focused on inorganic TE materials because of their superior performance.Very recently,due to the growing demands展开更多
Background A full-energy LINAC is under development at Wuhan Advanced Light Source(WALS)to provide beams for the 1.5 GeV storage ring proposed as a fourth-generation synchrotron radiation light source and a future fre...Background A full-energy LINAC is under development at Wuhan Advanced Light Source(WALS)to provide beams for the 1.5 GeV storage ring proposed as a fourth-generation synchrotron radiation light source and a future free electron laser(FEL)facility.The LINAC starts from a photoinjector that is able to produce electron beams with low emittance(<1 mm·mrad),small relative energy spread(<0.5%),and high bunch charge(~1 nC).Purpose and methods To minimize the output emittance and RMS bunch length for the purpose of improving the photoinjector brightness,the influence of different laser pulse profiles on the slice emittance is investigated,and the beam dynamics simulation is performed with non-dominated sorting genetic algorithm-II(NSGA-II)combining with ASTRA code to find the optimal solution at a bunch charge of 1 nC.Results and conclusion In this paper,the beam dynamics optimization of the photoinjector is presented in detail;the simulation results imply that the laser pulse profile with 1σtruncated Gaussian distribution in transverse and flat-top-like temporal distribution is beneficial to the improvement of beam brightness of the photoinjector,which shows an output emittance of 0.63 mm·mrad in the case of intrinsic thermal emittance of 0.43 mm·mrad.展开更多
Response surface methodology (RSM) was used to optimize the degree of esterification of p-coumaric acid to triolein via lipase-catalyzed acidolysis, and enzyme load, reaction time and mole ratio of substrates were sel...Response surface methodology (RSM) was used to optimize the degree of esterification of p-coumaric acid to triolein via lipase-catalyzed acidolysis, and enzyme load, reaction time and mole ratio of substrates were selected as variables in the experimental design. The results showed that the model employed was highly sufficient for determining the effectiveness and interaction of three selected variables, enzyme load, reaction time and the mole ratio of substrates, on the dependent variable, the degree of esterification. Although the optimization point was not found in the selected range of the three variables, the steepest ascent analysis suggested that an increase of these three variables might lead to a stationary point. However, based on the limitations on increasing the range of tested variables, including possible oxidation of synthesized lipids and increased cost, the degree of esterification so yielded in the designed central composite design should be the one closest to the possible ideal optimized degree. The p-coumarates so produced exhibited varying antioxidant performance in the tested muscle food model, which could be explained by their different lipophilicity. Moreover, the potential health benefits of synthesized phenolic lipids have been discussed.展开更多
The effects of ultrasound power on extraction kinetic model,and physicochemical and structural characteristics of collagen from chicken lung were studied.Ultrasound power caused a significant increase in extraction ra...The effects of ultrasound power on extraction kinetic model,and physicochemical and structural characteristics of collagen from chicken lung were studied.Ultrasound power caused a significant increase in extraction rate and equilibrium concentration,with the maximum extraction yield(31.25%)at 150 W.The experimental data were consistent with the predicted ones in this empirical equation,in which the percentage error differences was 0.026–4.159%.Besides,ultrasound treatment did not affect their triple-helical structure.The thermal stability of pepsin-soluble collagen by ultrasound pretreatment(UPSC)was higher,due to the higher imino acid content(20.76%).UPSC also exhibited better solubility and fibril forming capacity.Overall,the kinetic model of UPSC from chicken lung could serve the purpose of obtaining collagen,which displayed a potential alternative source to mammal collagens for application in food,biomaterials and biomedical fields.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFD17800)the National Natural Science Foundation of China(Nos.22078098,and 22278138)+2 种基金the Shanghai Academic Technology Research Leader(22XD1421000)the Research Funds of Happiness Flower ECNU(2020JK2103)the Open Funding Project of the State Key Laboratory of Bioreactor Engineering.
文摘In vivo imaging in the deep near-infrared(NIR)spectral region,that is,beyond 800 nm,has become popular due to its penetration depth.While imaging of the neutral medium/tissue has been repeatedly showcased,imaging of the high-acidic medium remains challenging partly because of the high-lying HOMO orbital and hence a high pKa of the electron-donating group of the NIR fluorophores.We devised a novel electron-donating group(D6)with which we further synthesized ECJ.ECJ exhibits an absorption wavelength beyond 900 nm and is fluorescent.Its pKa was found to be lower than zero,rendering it suitable for bioimaging of a highly-acidic medium.Its potential for practical applications was showcased in proof-of-concept in vivo imaging with a mouse model.
基金supported by the National Natural Science Foundation of China(Nos.T2441002 and 22175186)。
文摘A pair of asymmetric rigid carbazole-benzonitrile-based emitters were synthesized by strategically alternating donor and acceptor groups along the molecular edges.The spin-flip process is accelerated by both the formation of localized and delocalized charge transfer states due to linearly positioned donors and strong spin-orbital coupling between different excitation feature of the lowest singlet and triplet excited states.This molecular architecture results in a remarkable short delayed lifespan of around 100 ns.The application of the two emitters in organic light-emitting diodes(OLEDs)achieves the highest external quantum efficiencies of 13.0%for the green emitter and 9.1%for the sky-blue emitter.Impressively,these devices maintain their high efficiency even at high luminance levels.The sustained efficiency is ascribed to the effective suppression of exciton quenching by substantially shortening delayed lifespan.These findings underscore the practical utility of the molecular design strategy that incorporates alternate donor and acceptor groups at the molecular periphery for shortening delayed fluorescence lifetime,and hold great promise for the development of high-performance OLEDs.
基金supported by the National Key Research and Development Program of China(No.2022YFA1602200)the National Natural Science Foundation of China(Nos.12341501 and 12405174)the Hefei Comprehensive National Science Center for the strong support on the STCF key technology research project.
文摘Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy physics in the last two decades,a new-generation Tau-Charm factory,called the Super Tau-Charm Facility(STCF),has been actively promoted by the particle physics community in China.STCF has the potential to address fundamental questions such as the essence of color confinement and the matter-antimatter asymmetry within the next decades.The main design goals of the STCF are a center-of-mass energy ranging from 2 to 7 GeV and a luminosity surpassing 5×10^(34)cm^(−2)s^(−1)that is optimized at a center-of-mass energy of 4 GeV,which is approximately 50 times that of the currently operating Tau-Charm factory-BEPCII.The STCF accelerator has two main parts:a double-ring collider with a crab-waist collision scheme and an injector that provides top-up injections for both electron and positron beams.As a typical third-generation electron-positron circular collider,the STCF accelerator faces many challenges in both accelerator physics and technology.In this paper,the conceptual design of the STCF accelerator complex is presented,including the ongoing efforts and plans for technological research and develop-ment,as well as the required infrastructure.The STCF project aims to secure support from the Chinese central government for its construction during the 15th Five-Year Plan(2026-2030).
基金This research was financially supported by the National Key Research and Development Program of China(2017YFA0204700,2018YFE0200700)the National Natural Science Foundation of China(21805285)the Key Research Program of Frontier Sciences of CAS(QYZDY-SSW-SLH024).
文摘Electronic structures, which play a key role in determining electrical and optical properties of π-conjugated organic materials, have attracted tremendous interest. Efficient thermoelectric (TE) conversion of organic materials has rigorous requirements on electronic structures. Recently, the rational design and precise modulation of electronic structures have exhibited great potential in exploring state-of-the-art organic TE materials. This review focuses on the regulation of electronic structures of organic materials toward efficient TE conversion. First, we present the basic knowledge regarding electronic structures and the requirements for efficient TE conversion of organic materials, followed by a brief introduction of commonly used methods for electronic structure characterization. Next, we highlight the key strategies of electronic structure engineering for high-performance organic TE materials. Finally, an overview of the electronic structure engineering of organic TE materials, along with current challenges and future research directions, are provided.
基金supported by the Science and Technology Major Project of Hubei Province,China (No.2021AFB001).
文摘High-brightness electron beams are required to drive LINAC-based free-electron lasers(FELs)and storage-ring-based synchrotron radiation light sources.The bunch charge and RMS bunch length at the exit of the LINAC play a crucial role in the peak current;the minimum transverse emittance is mainly determined by the injector of the LINAC.Thus,a photoin-jector with a high bunch charge and low emittance that can simultaneously provide high-quality beams for 4th generation synchrotron radiation sources and FELs is desirable.The design of a 1.6-cell S-band 2998-MHz RF gun and beam dynamics optimization of a relevant beamline are presented in this paper.Beam dynamics simulations were performed by combining ASTRA and the multi-objective genetic algorithm NSGA II.The effects of the laser pulse shape,half-cell length of the RF gun,and RF parameters on the output beam quality were analyzed and compared.The normalized transverse emittance was optimized to be as low as 0.65 and 0.92 mm·mrad when the bunch charge was as high as 1 and 2 nC,respectively.Finally,the beam stability properties of the photoinjector,considering misalignment and RF jitter,were simulated and analyzed.
基金financially supported by the National Key Research and Development Program of China(No.2017YFA0204700)the National Natural Science Foundation of China(Nos.21805285,22175186 and 21803008)。
文摘Surface charge transfer doping of graphene plays an important role in graphene-based electronics due to its simplicity,high doping efficiency,and easy-controllability.Here,we demonstrate the effective surface charge transfer hole doping of graphene by using a strong p-type molecular dopant hexacyanotrimethylene-cyclopropane (CN6-CP).The CN6-CP exhibits a very high intrinsic work function of 6.37 e V,which facilitates remarkable electron transfer from graphene to CN6-CP as revealed by in situ photoelectron spectroscopy investigations.Consequently,hole accumulation appears in the graphene layer at the direct contact with CN6-CP.As evidenced by Hall effect measurements,the areal hole density of graphene significantly increased from 8.3×10^(12)cm^(-2) to 2.21×10^(13)cm^(-2) upon 6 nm CN6-CP evaporation.The CN6-CP acceptor with strong p-doping effect has great implications for both graphene-based and organic electronics.
基金financially supported by the National Natural Science Foundation of China(Nos.6197396,21905276)Natural Science Foundation of Beijing(No.4202077)+1 种基金Chinese Academy of Scinece(No.ZDBS-LY-SLH034)the Fundamental Research Funds for the Central Universities(No.E2ET0309X2)。
文摘Molecular structure of organic semiconductor plays a critical role in determining the performance and functionality of organic electronic devices,by optimizing the electrical,optical and physicochemical properties.Substituted alkyl chains are fundamental units in tailering the solubility and assemblability,among which the asymmetric properties have been reported as key element for controlling the packing motifs and intrinsic charge transport.Here,we expanded the scope of molecular asymmetry dependent sensing features based on a new series of naphthalene diimides(NDI)-based derivatives substituted with a same branching alkyl chain but various linear-shaped alkyl chains(Cn-).A clear molecular stacking change,from head-to-head bilayer to head-to-tail monolayer packing model,is observed based on the features of anisotropic molecular interactions with the change in the chain length.Most importantly,a unique LUMO level shift of 0.17 eV is validated for NDI-PhC4,providing a record sensitivity up to 150%to 0.01 ppb ammonia,due to the desired molecular reactivity and device amplification properties.These results indicate that asymmetric side-chain engineering opens a route for breath healthcare.
基金financial support from the National Natural Science Foundation of China(Nos.22125504,22175186,62205347,22305253,62075224,22021002 and 21805285)the Natural Science Foundation of Beijing(No.Z220025)the K.C.Wong Education Foundation(No.GJTD-2020-02)。
文摘Since the discovery of the Nernst effect in 19th century,it has been an important transverse thermoelectric charge transport phenomenon in solid states.Conjugated polymers have recently attracted great attention as promising optoelectronic materials.However,the Nernst effect is yet to be explored for conducting polymers.Here,we report the first theoretical investigations of the Nernst effect in doped conducting polymers by first-principles calculations under the frame work of Fermi-liquid theory.Specifically,the Nernst coefficients of PBTTT are found to be ranging from 0.0029 to 0.039μV K^(-1)T^(-1).They are monotonically decreased with the doping level due to both much enhanced Fermi energy and the decreased charge mobility at high doping level.Our theoretical findings not only enhance our fundamental understanding of the doping mechanism that controls the charge transport properties of conducting polymers,but more importantly,they also offer initial predictions of the transverse thermoelectric conversion capability of conducting polymers.These predictions are crucial for the development of future flexible thermoelectric applications based on the Nernst effect.
基金This work was supported by the National Natural Science Foundation of China(21573253)the National Key Research and Developmet Program of China(2017YFA0204700)the Strategic Priority Research Programme of the Chinese Academy of Sciences(XDB12010000).
文摘Two-dimensional(2D)atomically thin quantum dots(QDs)possess extraordinary electrical and optical properties.However,fabricating high quality 2D QDs via a universal and reliable technique remains a challenge.Here,we report a simple strategy to prepare high quality,monolayer single crystal 2D QDs via ultrathin cutting 2D bulk single crystals by ultramicrotome,followed by an exfoliation process.The as-prepared 2D QDs have pristine surface,high quality,high monolayer yield and high photoluminescence quantum yield(the highest photoluminescence quantum yield of WS2 is18%),which can be used as promising,low toxic,biocompatible,and good cell-permeability fluorescent labeling agents for in vitro imaging.
基金the National Natural Science Foundation of China(Nos.51873148,52073206,51633006,and 61704038)the Natural Science Foundation of Tianjin City(No.18JC-YBJC18400)Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000).
文摘Photogating and electrical gating are key physical mechanisms in organic phototransistors(OPTs).However,most OPTs are based on thick and polycrystalline films,which leads to substantially low efficiency of both photogating and electrical gating and thus reduced photoresponse.Herein,high-performance OPTs based on few-layered organic single-crystalline heterojunctions are proposed and the obstacle of thick and polycrystalline films for photodetection is overcome.Because of the molecular scale thickness of the type I organic single-crystalline heterojunctions in OPTs,both photogating and electrical gating are highly efficient.By synergy of efficient photogating and electrical gating,key figures of merit of OPTs reach the highest among those based on planar heterojunctions so far as we know.The production of few-layered organic single-crystalline heterojunctions will provide a new type of advanced materials for various applications.
基金supported by the National Natural Science Foundation of China(22125504,62205347,T2441002,22175186,22305253,22021002,U22A6002)the Natural Science Foundation of Beijing(Z220025)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0520200)the Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202402)。
文摘Conjugated polymers are attracting increased attention as thermoelectric(TE)materials for energy harvesting applications in low-temperature regimes.However,in many doped ambipolar polymers,the simultaneous transport of both holes and electrons under temperature gradients leads to an offset in thermopower(S),which suppresses TE performance and complicates intrinsic understanding of bipolar TE conversion.Herein,we quantitatively investigate the p-n polarity transition in FeCl_(3)-doped bipolar PDPP4T films by measuring the magneto-thermoelectric Nernst effect,combined with Hall and Seebeck effect analyses.Notably,behind the S=0 point,we observe a significant thermopower offset originating from the balancing contributions of electrons and holes.This countervailing thermopower value is extracted to reach 400μV K^(-1),which could ideally produce an estimated maximum unipolar ZT of 0.24 at 175 K,due to rising polaron states and reduced carrier concentration.Our findings reveal the extraordinary hidden unipolar TE performance achievable in doped bipolar polymer towards ultra-low-temperatures thermoelectric.
基金the National Key R&D Program(Nos.2016YFB0401100,2017YFA0204503)the National Natural Science Foundation of China(Nos.91833306,21875158,51633006,51703159,51733004).The authors acknowledge the Laboratory of Microfabrication,Institute of Physics,CAS,for their assistance in electrode fabrication。
文摘The spinterface formed between ferromagnetic(FM)electrode and organic materials is vital for performance optimization in organic spin valve(OSV).Half-metallic Fe_(3)O_(4)with drastic change in structure,conductivity and magnetic property near Verwey transition can serve as an intrinsic spinterface regulator.However,such modulating effect of Fe_(3)O_(4)in OSV has not been comprehensively investigated,especially below the Verwey transition temperature(Tv).Here,we highlight the important role of Fe_(3)O_(4)electrode in reliable-working and controllable Fe_(3)O_(4)/P3HT/Co polymer spin valves by investigating the magnetoresistance(MR)above and below 7V.In order to distinguish between different contributions to charge transport and related MR responses,the systematic electronic and magnetic characterizations were carried out in full temperature range.Particularly,the first-order metal-insulator transition in Fe_(3)O_(4)has a dramatic effect on the MR enhancement of polymer spin valves at 7V.Moreover,both the conducting mode transformation and MR line shape modulation could be accomplished across 7V.This research renders unique scenario to multimodal storage by external thermodynamic parameters,and further reveals the importance of spin-dependent interfacial modification in polymer spin valves.
基金supported by the Chinese Ministryof Science and Technology (2013CB632506, 2011CB932304)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB12000000)the National Natural Science Foundation of China(21290191, 21333011)
文摘Carbon films prepared from pyrolyzation of spin-casted polyacrylonitrile(PAN)thin films display high electrical conductivity(〉600 S/cm,at 1000℃carbonization),low sheet resistance(about 100 Y2/square at the PAN film thickness of 70 nm)and partial transmittance.These pyrolyzed PAN(PPAN)films were patterned as bottom electrodes by photolithography,and utilized as drain and source electrodes to fabricate organic field-effect transistor(OFET)devices with a p-type semiconductor(P3HT)and an n-type semiconductor(DPP-containing quinoidal small molecule)through a spin-coating procedure.The results showed that the devices with the PAN electrodes exhibited almost the same excellent performance without any further modification compared to those devices with traditional Au electrodes.Since these PPAN films had the advantages of low-cost,high performance,easier for large-area fabrication,thermal and chemical stability,it should be a promising electrode material for organic electrodes.
基金supported by the China Agriculture Research System(CARS-41)National Natural Science Foundation of China(31901612)Agricultural Science and Technology Innovation Fund Projects of Jiangsu Province(CX(18)1006).
文摘Developing efficient and promising tenderising techniques for postmortem meat is a heavily researched topic among meat scientists as consumers are willing to pay more for guaranteed tender meat.However,emerging tenderising techniques are not broadly used in the meat industry and,to some degree,are controversial due to lack of theoretical support.Thus,understanding the mechanisms involved in postmortem tenderisation is essential.This article first provides an overview of the relationship of ageing tenderisation and calpain system,as well as proteomics applied to identify protein biomarkers characterizing tenderness.In general,the ageing tenderisation is mediated by multiple biochemical activities,and it can exhibit better palatability and commercial benefit by combining other interventions.The calpain system plays a key role in ageing tenderisation functions by rupturing myofibrils and regulating proteolysis,glycolysis,apoptosis and metabolic modification.Additionally,tenderising techniques from different aspects including exogenous enzymes,chemistry,physics and the combined methods are discussed in depth.Particularly,innovation of home cooking could be recommended to prepare relatively tender meat due to its convenience and ease of operation by consumers.Furthermore,the combined interventions provide better performance in controlled tenderness.Finally,future trends in developing new tenderising techniques,and applied consideration in the meat processing industry are proposed in order to improve meat quality with higher economical value.
基金supported by the National Basic Research Program of China(2013CB632506)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB12000000)+1 种基金the National Natural Science Foundation of China(21333011)Chinese Academy of Sciences(QYZDY-SSW-SLH024)
文摘Thermoelectric(TE)materials can realize mutual energy conversion between heat and electricity and are applied broadly in energy harvesting,local cooling or heating,and thermal sensing[1].TE devices are crucial to solve the global energy crisis with renewable energy resources.Currently,most of the research works are focused on inorganic TE materials because of their superior performance.Very recently,due to the growing demands
基金supported by Science and Technology Major Project of Hubei Province in China(2021AFB001).
文摘Background A full-energy LINAC is under development at Wuhan Advanced Light Source(WALS)to provide beams for the 1.5 GeV storage ring proposed as a fourth-generation synchrotron radiation light source and a future free electron laser(FEL)facility.The LINAC starts from a photoinjector that is able to produce electron beams with low emittance(<1 mm·mrad),small relative energy spread(<0.5%),and high bunch charge(~1 nC).Purpose and methods To minimize the output emittance and RMS bunch length for the purpose of improving the photoinjector brightness,the influence of different laser pulse profiles on the slice emittance is investigated,and the beam dynamics simulation is performed with non-dominated sorting genetic algorithm-II(NSGA-II)combining with ASTRA code to find the optimal solution at a bunch charge of 1 nC.Results and conclusion In this paper,the beam dynamics optimization of the photoinjector is presented in detail;the simulation results imply that the laser pulse profile with 1σtruncated Gaussian distribution in transverse and flat-top-like temporal distribution is beneficial to the improvement of beam brightness of the photoinjector,which shows an output emittance of 0.63 mm·mrad in the case of intrinsic thermal emittance of 0.43 mm·mrad.
基金support from the Department of Science and Technology of Shaanxi Province, P. R. China (No. 2020NY-102)The author FS thanks the Natural Science and Engineering Research Council (NSERC) of Canada for support in the form of a Discovery Grant.
文摘Response surface methodology (RSM) was used to optimize the degree of esterification of p-coumaric acid to triolein via lipase-catalyzed acidolysis, and enzyme load, reaction time and mole ratio of substrates were selected as variables in the experimental design. The results showed that the model employed was highly sufficient for determining the effectiveness and interaction of three selected variables, enzyme load, reaction time and the mole ratio of substrates, on the dependent variable, the degree of esterification. Although the optimization point was not found in the selected range of the three variables, the steepest ascent analysis suggested that an increase of these three variables might lead to a stationary point. However, based on the limitations on increasing the range of tested variables, including possible oxidation of synthesized lipids and increased cost, the degree of esterification so yielded in the designed central composite design should be the one closest to the possible ideal optimized degree. The p-coumarates so produced exhibited varying antioxidant performance in the tested muscle food model, which could be explained by their different lipophilicity. Moreover, the potential health benefits of synthesized phenolic lipids have been discussed.
基金supported by National Natural Science Foundation of China(31901612)China agriculture research system(CARS-41)+2 种基金Natural Science Foundation Program of Jiangsu Province(BK20180300)Agricultural science and technology innovation fund projects of Jiangsu Province(CX(18)1006)Fundamental Research Funds for Jiangsu Academy of Agricultural Sciences(ZX(18)3009).
文摘The effects of ultrasound power on extraction kinetic model,and physicochemical and structural characteristics of collagen from chicken lung were studied.Ultrasound power caused a significant increase in extraction rate and equilibrium concentration,with the maximum extraction yield(31.25%)at 150 W.The experimental data were consistent with the predicted ones in this empirical equation,in which the percentage error differences was 0.026–4.159%.Besides,ultrasound treatment did not affect their triple-helical structure.The thermal stability of pepsin-soluble collagen by ultrasound pretreatment(UPSC)was higher,due to the higher imino acid content(20.76%).UPSC also exhibited better solubility and fibril forming capacity.Overall,the kinetic model of UPSC from chicken lung could serve the purpose of obtaining collagen,which displayed a potential alternative source to mammal collagens for application in food,biomaterials and biomedical fields.
