The Underwater Communication Link(UCL)is a crucial component of Underwater Wireless Optical Communication(UWOC)systems,requiring optimised design to mitigate the high power attenuation inherent in seawater.To ensure t...The Underwater Communication Link(UCL)is a crucial component of Underwater Wireless Optical Communication(UWOC)systems,requiring optimised design to mitigate the high power attenuation inherent in seawater.To ensure the reliability of an optimal UCL design,it is essential to account for the three primary scattering regimes:forward scattering(FSC),backward scattering(BSC),and isotropic scattering(ISC)in seawater channels.This study introduces a new photon-tracking model based on a discrete equation,facilitating Monte Carlo Simulation(MCS)to evaluate how different scattering regimes influence received photon distribution.Three distinct Scattering Regime Contribution Weight(SRCW)probability sets were employed,each representing different UCL operational configurations dominated by specific scattering regimes.The proposed modeling approach enables a comprehensive assessment of the temporal characteristics of received optical pulses,channel loss,and time spread-ultimately defining the optimal UCL design parameters.The key findings of this study include:(1)Enhancing the FSC regime dominance leads to a quasi-light waveguide effect over link spans and small Fields of View(FOV)<25°,significantly improving channel performance in Harbor seawater compared to Coastal seawater.(2)A well-designed UCL with a small FOV(<25°)can minimise channel loss and time spread,ensuring high capacity and efficient performance in both Coastal and Harbor seawaters.(3)When BSC and ISC contributions exceed FSC dominance,the received optical pulse undergoes significant temporal broadening,particularly for larger FOV angles(>25°)and extended link spans.(4)The developed novel MCS-based discrete equation provides a simple yet robust model for simulating photon propagation in both homogeneous and inhomogeneous underwater channels.These insights contribute to developing more efficient and reliable UCL designs with military standards by enhancing UWOC system performance over a longer linkspan for a given limited optical power across various underwater environments.展开更多
The rapid advancement of machine learning based tight-binding Hamiltonian(MLTB)methods has opened new avenues for efficient and accurate electronic structure simulations,particularly in large-scale systems and long-ti...The rapid advancement of machine learning based tight-binding Hamiltonian(MLTB)methods has opened new avenues for efficient and accurate electronic structure simulations,particularly in large-scale systems and long-time scenarios.This review begins with a concise overview of traditional tight-binding(TB)models,including both(semi-)empirical and first-principles approaches,establishing the foundation for understanding MLTB developments.We then present a systematic classification of existing MLTB methodologies,grouped into two major categories:direct prediction of TB Hamiltonian elements and inference of empirical parameters.A comparative analysis with other ML-based electronic structure models is also provided,highlighting the advancement of MLTB approaches.Finally,we explore the emerging MLTB application ecosystem,highlighting how the integration of MLTB models with a diverse suite of post-processing tools from linear-scaling solvers to quantum transport frameworks and molecular dynamics interfaces is essential for tackling complex scientific problems across different domains.The continued advancement of this integrated paradigm promises to accelerate materials discovery and open new frontiers in the predictive simulation of complex quantum phenomena.展开更多
Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in ...Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.展开更多
A novel photovoltaic cell with an active layer of poly（phenyleneethynylene） （PPE）/C60/N,N＇-diphenyl-N,N＇-di-（m-tolyl）-p-benzidine （TPD） is designed. In the active layer, PPE is the major component; C60 and T...A novel photovoltaic cell with an active layer of poly（phenyleneethynylene） （PPE）/C60/N,N＇-diphenyl-N,N＇-di-（m-tolyl）-p-benzidine （TPD） is designed. In the active layer, PPE is the major component; C60 and TPD are the minor ones. Compared with a control BHJ device based on PPE/C60, the short circuit current density Jsc is increased by 1 order of magnitude, and the whole device performance is increased greatly, however the open circuit voltage Voc is largely decreased. The possible mechanism of the improved performance may be as follows： In the PPE/C60/TPD device, PPE, C60, and TPD serve as the energy harvesting material, the electron transport material, and the hole transport material, respectively. As the TPD and C60 are spatially separated by PPE, the charge recombination is effectively retarded.展开更多
Cost-effective 3d transition metal(TM) based single atom catalysts(SACs) for oxygen reduction reaction(ORR) are potential alternatives for Pt-based electrocatalysts in fuel cells and metal-air batteries.Understanding ...Cost-effective 3d transition metal(TM) based single atom catalysts(SACs) for oxygen reduction reaction(ORR) are potential alternatives for Pt-based electrocatalysts in fuel cells and metal-air batteries.Understanding the effects of SACs’ properties and active site composition on the catalytic performance is significant to construct highly efficient catalysts. Here, we successfully promote the activity of cobalt single atoms decorated on N-doped carbon nanosheets via tuning the content of different nitrogen components, which outperforms most reported cobalt SACs. The activity and kinetics show positive correlation trends with the content of Co-Nxand graphitic N, serving as the main active sites.Furthermore, ORR kinetics in alkaline media can be positively affected by the conductivity of catalysts while no similar relation is observed in acidic media. The slight loss of Co-Nxsites engenders a mild change of performance in alkaline media, while the decrease of Co-Nxsite activity due to chemical oxidation of carbon support and the loss of Co-Nxsites in acidic media exacerbate the degradation of performance. Our work provides an insight into the relation between ORR electron transfer kinetics and active sites in 3d TM based SACs.展开更多
The last several years have witnessed the rapid developments in the study and understanding of topological insulators. In this review, after a brief summary of the history of topological insulators, we focus on the re...The last several years have witnessed the rapid developments in the study and understanding of topological insulators. In this review, after a brief summary of the history of topological insulators, we focus on the recent progress made in transport experiments on topological insulator films and nanowires. Some quantum phenomena, including the weak antilocalization, the Aharonov-Bobm effect, and the Shubnikov-de Haas oscillations, observed in these nanostructures are described. In addition, the electronic transport evidence of the superconducting proximity effect as well as an anomalous resistance enhancement in topological insulator/superconductor hybrid structures is included.展开更多
We investigate the dynamic quantities:momentum,spin and orbital angular momenta(SAM and OAM),and their conversion relationship in the structured optical fields at subwavelength scales,where the spin–orbit interaction...We investigate the dynamic quantities:momentum,spin and orbital angular momenta(SAM and OAM),and their conversion relationship in the structured optical fields at subwavelength scales,where the spin–orbit interaction(SOI)plays a key role and determines the behaviors of light.Specifically,we examine a nanostructure of a Ag nanoparticle(Ag NP)attached on a cylindrical Ag nanowire(Ag NW)under illumination of elliptically polarized light.These dynamic quantities obey the Noether theorem,i.e.,for the Ag nanoparticle with spherical symmetry,the total angular momentum consisting of SAM and OAM conserves;for the Ag NW with translational symmetry,the orbital momentum conserves.Meanwhile,the spin-to-orbital angular momentum conversion is mediated by SOI arising from the spatial variation of the optical potential.In this nanostructure,the conservation of momentum imposes a strict restriction on the propagation direction of the surface plasmon polaritons along the Ag NW.Meanwhile,the orbital momentum is determined by the polarized properties of the excitation light and the topography of the Ag NP.Our work offers insights to comprehend the light behaviors in the structured optical fields in terms of the dynamic quantities and benefits to the design of optical nano-devices based on interactions between spin and orbital degrees of freedom.展开更多
This paper reports that a charge-transfer salt dibutylammonium bis-7,7,8,8-tetraeyanoquinodimethane [DBA （TCNQ）2] has been prepared. The temperature dependences of the DC electrical conductivity of the DBA （TCNQ）2...This paper reports that a charge-transfer salt dibutylammonium bis-7,7,8,8-tetraeyanoquinodimethane [DBA （TCNQ）2] has been prepared. The temperature dependences of the DC electrical conductivity of the DBA （TCNQ）2 single crystal measured along the crystallographic a, b, and c axes are reported. The crystal shows semicondueting behaviour and the room-temperature conductivities are highly anisotropic （σa = 3.63× 10^-4S/cm, σb = 2.84× 10^-6S/cm, and （σe = 1.82 × 10^-5S/cm）. Particularly, a sharp semiconductor to semiconductor transition has been observed around 270 K on the resistivity curves measured under cooling and heating. In addition, thermal hysteresis phenomena on conductivity and differential scanning calorimetry curves are also reported.展开更多
We fabricate and characterize Au nanoparticle-aggregated nanowires by using the nano meniscus-induced colloidal stacking method. The Au nanoparticle solution ejects with guidance of nanopipette/quartz tuning fork-base...We fabricate and characterize Au nanoparticle-aggregated nanowires by using the nano meniscus-induced colloidal stacking method. The Au nanoparticle solution ejects with guidance of nanopipette/quartz tuning fork-based atomic force microscope in ambient conditions, and the stacking particles form Au nanoparticle-aggregated nanowire while the nozzle retracts from the surface. Their mechanical properties with relatively low elastic modulus are in situ investigated by using the same apparatus.展开更多
In this paper, we demonstrate a spin-controlled directional launching of surface plasmons at the subwavelength scale.Based on the principle of optical spin＇s effect for the geometric phase of light, the nanostructure...In this paper, we demonstrate a spin-controlled directional launching of surface plasmons at the subwavelength scale.Based on the principle of optical spin＇s effect for the geometric phase of light, the nanostructures were designed. The inclination of the structures decides the spin-related geometric phase and their relative positions decide the distance-related phase. Hence, the propagation direction of the generated surface plasmon polaritons（SPPs） can be controlled by the spin of photons. Numerical simulations by the finite difference time domain（FDTD） method have verified our theoretical prediction. Our structure is fabricated on the Au film by using a focused ion beam etching technique. The total size of the surface plasmon polariton（SPP） launcher is 320 nm by 180 nm. The observation of the SPP launching by using scanning near-field optical microscopy is in agreement with our theory and simulations. This result may provide a new way of spin-controlled directional launching of SPP.展开更多
The positively charged single walled carbon nanotubes （SWNTs^＋） were prepared by conjugating with -CONH-C6H12-NH3^＋. The double strand DNA （dsDNA） chains were loaded onto SWNTs^＋ via the electrostatic interacti...The positively charged single walled carbon nanotubes （SWNTs^＋） were prepared by conjugating with -CONH-C6H12-NH3^＋. The double strand DNA （dsDNA） chains were loaded onto SWNTs^＋ via the electrostatic interactions. SWNTs^＋ shows improved loading efficiency （353.5 μg/mg） toward dsDNA compared with that of charged free single walled carbon nanotubes （SWNTs） （82.9 μg/mg）.展开更多
本文报道用不同尺寸的金纳米粒子(AuNPs)来修饰单层WS2和MoS2纳米片,通过表面增强拉曼散射(SERS)技术检测微量的罗丹明6G染料,并对比了它们在不同波长的激光激发下的等离子体特性。AuNPs在WS2和MoS2纳米片上的均匀沉积是通过种子介导的...本文报道用不同尺寸的金纳米粒子(AuNPs)来修饰单层WS2和MoS2纳米片,通过表面增强拉曼散射(SERS)技术检测微量的罗丹明6G染料,并对比了它们在不同波长的激光激发下的等离子体特性。AuNPs在WS2和MoS2纳米片上的均匀沉积是通过种子介导的生长方法还原HAuCl4来实现的。我们进一步使用扫描电子显微镜和拉曼光谱对所制备的异质结构进行了表征。几种优化结构的拉曼增强因子接近108,几乎达到检测单分子需要的灵敏度。我们的研究结果表明,通过贵金属纳米粒子对超薄过渡金属双硫属元素化合物进行可控修饰是完全可行的。这个策略也适合于制备高效且灵活的基底,用在新一代基于表面增强拉曼散射的化学传感器和生物传感器上。Jason D Orlando 1,Ethan Kahn 2,Cindy Y Wong 3,Yin-ting Yeh 4,5,Tej B Limbu 1,Basant Chitara 1,Ana L Elias 4,5,Mauricio Terrones 4,5,YAN Fei(1.Department of Chemistry and Biochemistry,North Carolina Central University,Durham,NC.27707,USA;2.Department of Materials Science and Engineering,The Pennsylvania State University,University Park,PA.16802,USA;3.School for Engineering of Matter,Transport and Energy,Arizona State University,Tempe,AZ.85287,USA;4.Department of Physics,The Pennsylvania State University,University Park,PA.16802,USA;5.Center for Nanoscale Science,The Pennsylvania State University,University Park,PA.16802,USA)展开更多
A series of inkjet printing processes have been studied using graphene-based inks. Under optimized conditions, using water-soluble single-layered graphene oxide （GO） and few-layered graphene oxide （FGO）, various h...A series of inkjet printing processes have been studied using graphene-based inks. Under optimized conditions, using water-soluble single-layered graphene oxide （GO） and few-layered graphene oxide （FGO）, various high image quality patterns could be printed on diverse flexible substrates, including paper, poly（ethylene terephthalate） （PET） and polyimide （PI）, with a simple and low-cost inkjet printing technique. The graphene-based patterns printed on plastic substrates demonstrated a high electrical conductivity after thermal reduction, and more importantly, they retained the same conductivity over severe bending cycles. Accordingly, flexible electric circuits and a hydrogen peroxide chemical sensor were fabricated and showed excellent performances, demonstrating the applications of this simple and practical inkjet printing technique using graphene inks. The results show that graphene materials--which can be easily produced on a large scale and possess outstanding electronic properties--have great potential for the convenient fabrication of flexible and low-cost graphene- based electronic devices, by using a simple inkjet printing technique.展开更多
p-Phenylenediamine(PPD)functionalized graphene oxide(GO)materials(PPDG)were prepared through a one-step solvothermal process and their application as supercapacitors(SCs)were studied.The PPD is not only as the spacers...p-Phenylenediamine(PPD)functionalized graphene oxide(GO)materials(PPDG)were prepared through a one-step solvothermal process and their application as supercapacitors(SCs)were studied.The PPD is not only as the spacers to prevent aggregating and restacking of the graphene sheets in the preparing process but also as nitrogen sources to obtain the nitrogen-doped graphene.The structures of PPDG were characterized by Fourier transformed infrared spectroscopy(FT-IR),X-ray diffraction spectroscopy(XRD),Raman spectroscopy and X-ray photoelectron spectroscopy(XPS)and the results show that the nitrogen-doped graphene was achieved with nitrogen content as high as 10.85 at.%.The field emission scanning electron microscopy(FE-SEM)and high resolution transmission electron microscopy(HR-TEM)have confirmed that the morphologies of PPDG were loose layered with less aggregation,indicating that PPD molecules,as spacers,effectively prevent the graphene sheets from restacking during the solvothermal reaction.The special loose textures make PPDG materials exhibit excellent electrochemical performance for symmetric SCs with superior specific capacitance(313 F/g at 0.1 A/g),rate capability and cycling stability.The present synthesis method is convenient and may have potential applications as ultrahigh performance SCs.展开更多
Strong chemical interactions between the oxygen-containing functional groups on graphene oxide(GO)sheets and the ions of divalent metals were exploited for the softening of hard water.GO membranes were prepared and ev...Strong chemical interactions between the oxygen-containing functional groups on graphene oxide(GO)sheets and the ions of divalent metals were exploited for the softening of hard water.GO membranes were prepared and evaluated for their ability to absorb Ca2+and Mg2+ions.These GO membranes can effectively absorb Ca2+ions from hard water;a 1 mg GO membrane can remove as much as 0.05 mg Ca2+ions.These GO membranes can be regenerated and used repeatedly.展开更多
Dosage of chemotherapeutic drugs is a tradeoff between efficacy and side-effects.Liposomes are nanocarriers that increase therapy efficacy and minimize side-effects by delivering otherwise difficult to administer ther...Dosage of chemotherapeutic drugs is a tradeoff between efficacy and side-effects.Liposomes are nanocarriers that increase therapy efficacy and minimize side-effects by delivering otherwise difficult to administer therapeutics with improved efficiency and selectivity.Still,variabilities in liposome preparation require assessing drug encapsulation efficiency at the single liposome level,an information that,for non-fluorescent therapeutic cargos,is inaccessible due to the minute drug load per liposome.Photothermal induced resonance (PTIR) provides nanoscale compositional specificity,up to now,by leveraging an atomic force microscope (AFM) tip contacting the sample to transduce the sample's photothermal expansion.However,on soft samples (e.g.,liposomes) PTIR effectiveness is reduced due to the likelihood of tip-induced sample damage and inefficient AFM transduction.Here,individual liposomes loaded with the chemotherapeutic drug cytarabine are deposited intact from suspension via nano-electrospray gas-phase electrophoretic mobility molecular analysis (nES-GEMMA) collection and characterized at the nanoscale with the chemically-sensitive PTIR method.A new tapping-mode PTIR imaging paradigm based on heterodyne detection is shown to be better adapted to measure soft samples,yielding cytarabine distribution in individual liposomes and enabling classification of empty and drug-loaded liposomes.The measurements highlight PTIR capability to detect ~ 103 cytarabine molecules (~ 1.7 zmol) label-free and non-destructively.展开更多
The possible practical limits for the specific surface area and capacitance performance of bulk sp^2 carbon materials were investigated experimentally and theoretically using a variety of carbon materials. We find the...The possible practical limits for the specific surface area and capacitance performance of bulk sp^2 carbon materials were investigated experimentally and theoretically using a variety of carbon materials. We find the limit for the specific surface area to be 3500–3700 m^2 g^(-1), and based on this, the corresponding best capacitance was predicted for various electrolyte systems. A model using an effective ionic diameter for the electrolyte ions was proposed and used to calculate the theoretical capacitance. A linear dependence of experimental capacitance versus effective specific surface area of various sp^2 carbon materials was obtained for all studied ionic liquid, organic and aqueous electrolyte systems. Furthermore, excellent agreement between the theoretical and experimental capacitance was observed for all the tested sp^2 carbon materials in these electrolyte systems, indicating that this model can be applied widely in the evaluation of various carbon materials for supercapacitors.展开更多
Au atoms were vaporized by electron beam evaporation, and their subsequent growths on Si (111 ) and highly ordered pyrolytic graphite (HOPG) substrates were studied using atomic force microscopy. Results show that Au ...Au atoms were vaporized by electron beam evaporation, and their subsequent growths on Si (111 ) and highly ordered pyrolytic graphite (HOPG) substrates were studied using atomic force microscopy. Results show that Au nanoparticles tend to nucleate and grow regularly along the step edges of HOPG, however, nanoparticles are distributed homogeneously over the whole Si substrate. The possibility of controlled growth of Au in ultrahigh vacuum with peculiar surface structures was preseuted.展开更多
Ba(Mg_(1/3)Nb_(2/3))O_(3)(BMN)doped and undoped B_(0.45)Sr_(0.55)TiO_(3)(BST)thin films were deposited via radio frequency magnetron sputtering on PUTiO_(2)/SiO_(2)/Al_(2)O_(3) substrates.The surface morphology and ch...Ba(Mg_(1/3)Nb_(2/3))O_(3)(BMN)doped and undoped B_(0.45)Sr_(0.55)TiO_(3)(BST)thin films were deposited via radio frequency magnetron sputtering on PUTiO_(2)/SiO_(2)/Al_(2)O_(3) substrates.The surface morphology and chemical state analyses of the films have shown that the BMN doped BST film has a smoother surface with reduced oxygen vacancy,resulting in an improved insulating properties of the BST film.Dielectric tunability,loss,and leakage current(LC)of the undoped and BMN doped BST thin flms were studied.The BMN dopant has remarkably reduced the dielectric loss(~38%)with no significant effect on the tunability of the BST film,leading to an increase in figure of merit(FOM).This is attributed to the opposing behavior of large Mg2+whose detrimental effect on tunability is partially compensated by small Nb5+as the two substitute Ti4+in the BST.The coupling between Mg″_(Ti)and V_(o)charged defects suppresses the dielectric loss in the film by cutting electrons from hopping between Ti ions.The LC of the films was investigated in the temperature range of 300-450K.A reduced LC measured for the BMN doped BST film was correlated to the formation of defect dipoles from Mg″_(Ti),V_(o)and Nb_(Ti) charged defects.The carrier transport properties of the films were analyzed in light of Schottky thermionic emission(SE)and Poole-Frenkel(PF)enmission mechanisms.The result indicated that while the carrier transport mechanism in the undoped film is interface limited(SE),the conduction in the BMN doped film was dominated by bulk processes(PF).The change of the conduction mechanism from SE to PF as a result of BMN doping is atributed to the presence of uncoupled Nb_(Ti) stting as a positive trap center at the shallow donor level of the BST.展开更多
基金The Deanship of Scientific Research(DSR)at King Abdulaziz University(KAU),Jeddah,Saudi Arabia,has funded this project under Grant No.(KEP-PhD:72-130-1443).
文摘The Underwater Communication Link(UCL)is a crucial component of Underwater Wireless Optical Communication(UWOC)systems,requiring optimised design to mitigate the high power attenuation inherent in seawater.To ensure the reliability of an optimal UCL design,it is essential to account for the three primary scattering regimes:forward scattering(FSC),backward scattering(BSC),and isotropic scattering(ISC)in seawater channels.This study introduces a new photon-tracking model based on a discrete equation,facilitating Monte Carlo Simulation(MCS)to evaluate how different scattering regimes influence received photon distribution.Three distinct Scattering Regime Contribution Weight(SRCW)probability sets were employed,each representing different UCL operational configurations dominated by specific scattering regimes.The proposed modeling approach enables a comprehensive assessment of the temporal characteristics of received optical pulses,channel loss,and time spread-ultimately defining the optimal UCL design parameters.The key findings of this study include:(1)Enhancing the FSC regime dominance leads to a quasi-light waveguide effect over link spans and small Fields of View(FOV)<25°,significantly improving channel performance in Harbor seawater compared to Coastal seawater.(2)A well-designed UCL with a small FOV(<25°)can minimise channel loss and time spread,ensuring high capacity and efficient performance in both Coastal and Harbor seawaters.(3)When BSC and ISC contributions exceed FSC dominance,the received optical pulse undergoes significant temporal broadening,particularly for larger FOV angles(>25°)and extended link spans.(4)The developed novel MCS-based discrete equation provides a simple yet robust model for simulating photon propagation in both homogeneous and inhomogeneous underwater channels.These insights contribute to developing more efficient and reliable UCL designs with military standards by enhancing UWOC system performance over a longer linkspan for a given limited optical power across various underwater environments.
基金supported by the Advanced Materials-National Science and Technology Major Project(Grant No.2025ZD0618401)the National Natural Science Foundation of China(Grant No.12504285)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20250472)NFSG grant from BITS-Pilani,Dubai campus。
文摘The rapid advancement of machine learning based tight-binding Hamiltonian(MLTB)methods has opened new avenues for efficient and accurate electronic structure simulations,particularly in large-scale systems and long-time scenarios.This review begins with a concise overview of traditional tight-binding(TB)models,including both(semi-)empirical and first-principles approaches,establishing the foundation for understanding MLTB developments.We then present a systematic classification of existing MLTB methodologies,grouped into two major categories:direct prediction of TB Hamiltonian elements and inference of empirical parameters.A comparative analysis with other ML-based electronic structure models is also provided,highlighting the advancement of MLTB approaches.Finally,we explore the emerging MLTB application ecosystem,highlighting how the integration of MLTB models with a diverse suite of post-processing tools from linear-scaling solvers to quantum transport frameworks and molecular dynamics interfaces is essential for tackling complex scientific problems across different domains.The continued advancement of this integrated paradigm promises to accelerate materials discovery and open new frontiers in the predictive simulation of complex quantum phenomena.
文摘Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60676051, 20644004, and 07JCYBJC03000, the Tianjin Natural Science Foundation （06TXTJJC14603）, the National Basic Research Program of China under Grant No 2006CBON0702）, the Specialized Research Fund for the Doctoral Programme of Higher Education of China under Grant No 20040055020, and Tianjin Key Laboratory for Photoelectric Materials and Devices.
文摘A novel photovoltaic cell with an active layer of poly（phenyleneethynylene） （PPE）/C60/N,N＇-diphenyl-N,N＇-di-（m-tolyl）-p-benzidine （TPD） is designed. In the active layer, PPE is the major component; C60 and TPD are the minor ones. Compared with a control BHJ device based on PPE/C60, the short circuit current density Jsc is increased by 1 order of magnitude, and the whole device performance is increased greatly, however the open circuit voltage Voc is largely decreased. The possible mechanism of the improved performance may be as follows： In the PPE/C60/TPD device, PPE, C60, and TPD serve as the energy harvesting material, the electron transport material, and the hole transport material, respectively. As the TPD and C60 are spatially separated by PPE, the charge recombination is effectively retarded.
基金financial support from the Natural Science Foundation of Beijing Municipality (2191001)the National Natural Science Foundation of China (51631001, 51672010 and 52001007)+1 种基金the National Key R&D Program of China(2017YFA0206301)the China Postdoctoral Science Foundation (2020M670038)。
文摘Cost-effective 3d transition metal(TM) based single atom catalysts(SACs) for oxygen reduction reaction(ORR) are potential alternatives for Pt-based electrocatalysts in fuel cells and metal-air batteries.Understanding the effects of SACs’ properties and active site composition on the catalytic performance is significant to construct highly efficient catalysts. Here, we successfully promote the activity of cobalt single atoms decorated on N-doped carbon nanosheets via tuning the content of different nitrogen components, which outperforms most reported cobalt SACs. The activity and kinetics show positive correlation trends with the content of Co-Nxand graphitic N, serving as the main active sites.Furthermore, ORR kinetics in alkaline media can be positively affected by the conductivity of catalysts while no similar relation is observed in acidic media. The slight loss of Co-Nxsites engenders a mild change of performance in alkaline media, while the decrease of Co-Nxsite activity due to chemical oxidation of carbon support and the loss of Co-Nxsites in acidic media exacerbate the degradation of performance. Our work provides an insight into the relation between ORR electron transfer kinetics and active sites in 3d TM based SACs.
基金supported by the National Basic Research Program of China (Grant Nos. 2013CB934600 and 2012CB921300)the National Natural Science Foundation of China (Grant Nos. 11222434 and 11174007)the Pennsylvania State University Materials Research Science and Engineering Center under National Science Foundation (Grant No. DMR-0820404)
文摘The last several years have witnessed the rapid developments in the study and understanding of topological insulators. In this review, after a brief summary of the history of topological insulators, we focus on the recent progress made in transport experiments on topological insulator films and nanowires. Some quantum phenomena, including the weak antilocalization, the Aharonov-Bobm effect, and the Shubnikov-de Haas oscillations, observed in these nanostructures are described. In addition, the electronic transport evidence of the superconducting proximity effect as well as an anomalous resistance enhancement in topological insulator/superconductor hybrid structures is included.
基金National Key R&D Program of China(Grant Nos.2017YFA0205700,2015CB932403,and 2017YFA0206000)the National Natural Science Foundation of China(Grant Nos.21790364,11374023,61422501,11674012,61176120,61378059,6097701,and 61521004).
文摘We investigate the dynamic quantities:momentum,spin and orbital angular momenta(SAM and OAM),and their conversion relationship in the structured optical fields at subwavelength scales,where the spin–orbit interaction(SOI)plays a key role and determines the behaviors of light.Specifically,we examine a nanostructure of a Ag nanoparticle(Ag NP)attached on a cylindrical Ag nanowire(Ag NW)under illumination of elliptically polarized light.These dynamic quantities obey the Noether theorem,i.e.,for the Ag nanoparticle with spherical symmetry,the total angular momentum consisting of SAM and OAM conserves;for the Ag NW with translational symmetry,the orbital momentum conserves.Meanwhile,the spin-to-orbital angular momentum conversion is mediated by SOI arising from the spatial variation of the optical potential.In this nanostructure,the conservation of momentum imposes a strict restriction on the propagation direction of the surface plasmon polaritons along the Ag NW.Meanwhile,the orbital momentum is determined by the polarized properties of the excitation light and the topography of the Ag NP.Our work offers insights to comprehend the light behaviors in the structured optical fields in terms of the dynamic quantities and benefits to the design of optical nano-devices based on interactions between spin and orbital degrees of freedom.
基金Project supported by the National Natural Science Foundation of China (Grant No 10604038)the Program for New Century Excellent Talents in University (NCET-2007)
文摘This paper reports that a charge-transfer salt dibutylammonium bis-7,7,8,8-tetraeyanoquinodimethane [DBA （TCNQ）2] has been prepared. The temperature dependences of the DC electrical conductivity of the DBA （TCNQ）2 single crystal measured along the crystallographic a, b, and c axes are reported. The crystal shows semicondueting behaviour and the room-temperature conductivities are highly anisotropic （σa = 3.63× 10^-4S/cm, σb = 2.84× 10^-6S/cm, and （σe = 1.82 × 10^-5S/cm）. Particularly, a sharp semiconductor to semiconductor transition has been observed around 270 K on the resistivity curves measured under cooling and heating. In addition, thermal hysteresis phenomena on conductivity and differential scanning calorimetry curves are also reported.
基金supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No. 200983512)Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2013R1A6A3A03063900)the Brain Korea 21
文摘We fabricate and characterize Au nanoparticle-aggregated nanowires by using the nano meniscus-induced colloidal stacking method. The Au nanoparticle solution ejects with guidance of nanopipette/quartz tuning fork-based atomic force microscope in ambient conditions, and the stacking particles form Au nanoparticle-aggregated nanowire while the nozzle retracts from the surface. Their mechanical properties with relatively low elastic modulus are in situ investigated by using the same apparatus.
基金supported by the National Natural Science Foundation of China(Grant Nos.61176120,61378059,60977015,61422501,and 11374023)the National Basic Research Program of China(Grant Nos.2012CB933004 and 2015CB932403)Beijing Natural Science Foundation(Grant No.L140007)
文摘In this paper, we demonstrate a spin-controlled directional launching of surface plasmons at the subwavelength scale.Based on the principle of optical spin＇s effect for the geometric phase of light, the nanostructures were designed. The inclination of the structures decides the spin-related geometric phase and their relative positions decide the distance-related phase. Hence, the propagation direction of the generated surface plasmon polaritons（SPPs） can be controlled by the spin of photons. Numerical simulations by the finite difference time domain（FDTD） method have verified our theoretical prediction. Our structure is fabricated on the Au film by using a focused ion beam etching technique. The total size of the surface plasmon polariton（SPP） launcher is 320 nm by 180 nm. The observation of the SPP launching by using scanning near-field optical microscopy is in agreement with our theory and simulations. This result may provide a new way of spin-controlled directional launching of SPP.
文摘The positively charged single walled carbon nanotubes （SWNTs^＋） were prepared by conjugating with -CONH-C6H12-NH3^＋. The double strand DNA （dsDNA） chains were loaded onto SWNTs^＋ via the electrostatic interactions. SWNTs^＋ shows improved loading efficiency （353.5 μg/mg） toward dsDNA compared with that of charged free single walled carbon nanotubes （SWNTs） （82.9 μg/mg）.
基金supported in part by the U.S.National Science Foundation(Awards#1831133 and#1523617)
文摘本文报道用不同尺寸的金纳米粒子(AuNPs)来修饰单层WS2和MoS2纳米片,通过表面增强拉曼散射(SERS)技术检测微量的罗丹明6G染料,并对比了它们在不同波长的激光激发下的等离子体特性。AuNPs在WS2和MoS2纳米片上的均匀沉积是通过种子介导的生长方法还原HAuCl4来实现的。我们进一步使用扫描电子显微镜和拉曼光谱对所制备的异质结构进行了表征。几种优化结构的拉曼增强因子接近108,几乎达到检测单分子需要的灵敏度。我们的研究结果表明,通过贵金属纳米粒子对超薄过渡金属双硫属元素化合物进行可控修饰是完全可行的。这个策略也适合于制备高效且灵活的基底,用在新一代基于表面增强拉曼散射的化学传感器和生物传感器上。Jason D Orlando 1,Ethan Kahn 2,Cindy Y Wong 3,Yin-ting Yeh 4,5,Tej B Limbu 1,Basant Chitara 1,Ana L Elias 4,5,Mauricio Terrones 4,5,YAN Fei(1.Department of Chemistry and Biochemistry,North Carolina Central University,Durham,NC.27707,USA;2.Department of Materials Science and Engineering,The Pennsylvania State University,University Park,PA.16802,USA;3.School for Engineering of Matter,Transport and Energy,Arizona State University,Tempe,AZ.85287,USA;4.Department of Physics,The Pennsylvania State University,University Park,PA.16802,USA;5.Center for Nanoscale Science,The Pennsylvania State University,University Park,PA.16802,USA)
基金Acknowledgements The authors gratefully acknowledge financial support from the the National Natural Science Foundation of China （Grants No. 50933003, 50902073, 50903044, and 20774047）, Ministry of Science and Technology of China （Grant No. 2009AA032304, 2011CB932602）, Natural Science Foundation of Tianjin City （Grant No. 08JCZDJC25300）.
文摘A series of inkjet printing processes have been studied using graphene-based inks. Under optimized conditions, using water-soluble single-layered graphene oxide （GO） and few-layered graphene oxide （FGO）, various high image quality patterns could be printed on diverse flexible substrates, including paper, poly（ethylene terephthalate） （PET） and polyimide （PI）, with a simple and low-cost inkjet printing technique. The graphene-based patterns printed on plastic substrates demonstrated a high electrical conductivity after thermal reduction, and more importantly, they retained the same conductivity over severe bending cycles. Accordingly, flexible electric circuits and a hydrogen peroxide chemical sensor were fabricated and showed excellent performances, demonstrating the applications of this simple and practical inkjet printing technique using graphene inks. The results show that graphene materials--which can be easily produced on a large scale and possess outstanding electronic properties--have great potential for the convenient fabrication of flexible and low-cost graphene- based electronic devices, by using a simple inkjet printing technique.
基金supported by the Ministry of Science and Technology (2012CB933401,2014CB643502)the National Natural Science Foundation of China (51273093,21374050,51373078)+2 种基金Natural Science Foundation of Tianjin (10ZCGHHZ00600)the Synergetic Innovation Center of Chemical Science and Engineering (Tianjin),Science and Technology Research Project of Higher Education of Hebei Province (z2012064)Science Research Project of Langfang Teachers College (LSZQ200908)
文摘p-Phenylenediamine(PPD)functionalized graphene oxide(GO)materials(PPDG)were prepared through a one-step solvothermal process and their application as supercapacitors(SCs)were studied.The PPD is not only as the spacers to prevent aggregating and restacking of the graphene sheets in the preparing process but also as nitrogen sources to obtain the nitrogen-doped graphene.The structures of PPDG were characterized by Fourier transformed infrared spectroscopy(FT-IR),X-ray diffraction spectroscopy(XRD),Raman spectroscopy and X-ray photoelectron spectroscopy(XPS)and the results show that the nitrogen-doped graphene was achieved with nitrogen content as high as 10.85 at.%.The field emission scanning electron microscopy(FE-SEM)and high resolution transmission electron microscopy(HR-TEM)have confirmed that the morphologies of PPDG were loose layered with less aggregation,indicating that PPD molecules,as spacers,effectively prevent the graphene sheets from restacking during the solvothermal reaction.The special loose textures make PPDG materials exhibit excellent electrochemical performance for symmetric SCs with superior specific capacitance(313 F/g at 0.1 A/g),rate capability and cycling stability.The present synthesis method is convenient and may have potential applications as ultrahigh performance SCs.
基金supported by the Ministry of Science and Technology of China(Grant No.2012CB933401)the National Natural Science Foundation of China(Grant Nos.21374050 and 51373078)
文摘Strong chemical interactions between the oxygen-containing functional groups on graphene oxide(GO)sheets and the ions of divalent metals were exploited for the softening of hard water.GO membranes were prepared and evaluated for their ability to absorb Ca2+and Mg2+ions.These GO membranes can effectively absorb Ca2+ions from hard water;a 1 mg GO membrane can remove as much as 0.05 mg Ca2+ions.These GO membranes can be regenerated and used repeatedly.
文摘Dosage of chemotherapeutic drugs is a tradeoff between efficacy and side-effects.Liposomes are nanocarriers that increase therapy efficacy and minimize side-effects by delivering otherwise difficult to administer therapeutics with improved efficiency and selectivity.Still,variabilities in liposome preparation require assessing drug encapsulation efficiency at the single liposome level,an information that,for non-fluorescent therapeutic cargos,is inaccessible due to the minute drug load per liposome.Photothermal induced resonance (PTIR) provides nanoscale compositional specificity,up to now,by leveraging an atomic force microscope (AFM) tip contacting the sample to transduce the sample's photothermal expansion.However,on soft samples (e.g.,liposomes) PTIR effectiveness is reduced due to the likelihood of tip-induced sample damage and inefficient AFM transduction.Here,individual liposomes loaded with the chemotherapeutic drug cytarabine are deposited intact from suspension via nano-electrospray gas-phase electrophoretic mobility molecular analysis (nES-GEMMA) collection and characterized at the nanoscale with the chemically-sensitive PTIR method.A new tapping-mode PTIR imaging paradigm based on heterodyne detection is shown to be better adapted to measure soft samples,yielding cytarabine distribution in individual liposomes and enabling classification of empty and drug-loaded liposomes.The measurements highlight PTIR capability to detect ~ 103 cytarabine molecules (~ 1.7 zmol) label-free and non-destructively.
基金supported by the National Basic Research Program of China(2012CB933401)the National Natural Science Foundation of China(51472124+3 种基金5127309321374050)the Natural Science Foundation of Tianjin(13RCGFGX01121)Science Research Project of Langfang Teachers University(LSLB201401)
文摘The possible practical limits for the specific surface area and capacitance performance of bulk sp^2 carbon materials were investigated experimentally and theoretically using a variety of carbon materials. We find the limit for the specific surface area to be 3500–3700 m^2 g^(-1), and based on this, the corresponding best capacitance was predicted for various electrolyte systems. A model using an effective ionic diameter for the electrolyte ions was proposed and used to calculate the theoretical capacitance. A linear dependence of experimental capacitance versus effective specific surface area of various sp^2 carbon materials was obtained for all studied ionic liquid, organic and aqueous electrolyte systems. Furthermore, excellent agreement between the theoretical and experimental capacitance was observed for all the tested sp^2 carbon materials in these electrolyte systems, indicating that this model can be applied widely in the evaluation of various carbon materials for supercapacitors.
基金Project supported by the Ministry of Science and Technology of China (2001CB6105) and the National Natural Science Foundation of China (NSFC 599101611982, 29973001)
文摘Au atoms were vaporized by electron beam evaporation, and their subsequent growths on Si (111 ) and highly ordered pyrolytic graphite (HOPG) substrates were studied using atomic force microscopy. Results show that Au nanoparticles tend to nucleate and grow regularly along the step edges of HOPG, however, nanoparticles are distributed homogeneously over the whole Si substrate. The possibility of controlled growth of Au in ultrahigh vacuum with peculiar surface structures was preseuted.
基金This publication is based on research sponsored by the Defense Microelectronics Activity(DMEA)under agreement number H94003-11-2-1103.
文摘Ba(Mg_(1/3)Nb_(2/3))O_(3)(BMN)doped and undoped B_(0.45)Sr_(0.55)TiO_(3)(BST)thin films were deposited via radio frequency magnetron sputtering on PUTiO_(2)/SiO_(2)/Al_(2)O_(3) substrates.The surface morphology and chemical state analyses of the films have shown that the BMN doped BST film has a smoother surface with reduced oxygen vacancy,resulting in an improved insulating properties of the BST film.Dielectric tunability,loss,and leakage current(LC)of the undoped and BMN doped BST thin flms were studied.The BMN dopant has remarkably reduced the dielectric loss(~38%)with no significant effect on the tunability of the BST film,leading to an increase in figure of merit(FOM).This is attributed to the opposing behavior of large Mg2+whose detrimental effect on tunability is partially compensated by small Nb5+as the two substitute Ti4+in the BST.The coupling between Mg″_(Ti)and V_(o)charged defects suppresses the dielectric loss in the film by cutting electrons from hopping between Ti ions.The LC of the films was investigated in the temperature range of 300-450K.A reduced LC measured for the BMN doped BST film was correlated to the formation of defect dipoles from Mg″_(Ti),V_(o)and Nb_(Ti) charged defects.The carrier transport properties of the films were analyzed in light of Schottky thermionic emission(SE)and Poole-Frenkel(PF)enmission mechanisms.The result indicated that while the carrier transport mechanism in the undoped film is interface limited(SE),the conduction in the BMN doped film was dominated by bulk processes(PF).The change of the conduction mechanism from SE to PF as a result of BMN doping is atributed to the presence of uncoupled Nb_(Ti) stting as a positive trap center at the shallow donor level of the BST.
