Multidimensional confined structure systems are proposed and demonstrated by using MoO_(2)@MO_(2)C(MMC)to enhance the photothermal catalytic performance of the metal sulfides-multidimensional confined structure(TMs-MD...Multidimensional confined structure systems are proposed and demonstrated by using MoO_(2)@MO_(2)C(MMC)to enhance the photothermal catalytic performance of the metal sulfides-multidimensional confined structure(TMs-MDCS).Specifically,the MMC nanoparticles confined to the surface of the ZnIn_(2)S_(4)hollow tube-shell(MMC/HT-ZIS)achieve a hydrogen evolution rate of 9.72 mmol g^(-1)h^(-1),which is 11.2 times higher than that of pure HT-ZIS.Meanwhile,the MnCdS(MCS)nanoparticles are encapsulated within the two-dimensional MMC(2D MMC/MCS)through precise regulation of size and morphology.The 10-MMC/MCS lamellar network demonstrates the highest hydrogen evolution rate of 8.19 mmol g^(-1)-h^(-1).The obtained MMC/TMs-MDCS catalysts exhibit an enhanced photocatalytic hydrogen evolution rate,which can be attributed to the strong synergistic interaction between the multidimensional confinement and the photothermal effects.The confinement space and the strong interfacial relationship within the MMC/TMs-MDCS create abundant channels and active sites that facilitate electron migration and transport.Furthermore,the construction of a confined environment positions these materials as promising candidates for achieving exceptional photothermal catalytic performance,as MMC/TMs-MDCS enhance light absorption through light scattering and reflecting effects.Additionally,the capacity of MMC/TMsMDCS to convert solar light into thermal energy significantly reduces the activation energy of the reaction,thereby facilitating reaction kinetics and accelerating the separation and transport of photogenerated carriers.This work provides valuable insights for the development of highly efficient photothermal catalytic water-splitting systems for hydrogen production using multidimensional confined catalysts.展开更多
This study addresses the challenge by introducing a piezoelectric energy harvester based on vortex-induced vibration(VIV)and galloping interactions.Experiments on an elastically mounted circular cylinder equipped with...This study addresses the challenge by introducing a piezoelectric energy harvester based on vortex-induced vibration(VIV)and galloping interactions.Experiments on an elastically mounted circular cylinder equipped with two small square rods(SSR)in a DN100 pipe were conducted to examine how the circumferential angle of the SSR impacts the vibration response of cylinder,revealing distinct interaction modes(VIV-only and VIV-galloping interaction).The results show that placing the SSR toward the bluff body’s trailing edge accelerates the onset of galloping at lower velocities.In particular,as the SSR angle is in the range ofθ=160°–180°,the fluid-structure interaction behavior deviates from prior open-flow studies.This difference is attributed to the influence of the pipe wall and is analyzed using the shear layer interaction mode theory.The relationship between SSR placement angles and fluid-induced vibration(FIV)characteristics across various fluid velocities was also mapped,with dynamic influences assessed using the Strouhal number and stability parameterΔS,helping to distinguish between interaction modes.Based on these findings,configurations withθ=50°–70°andθ=140°–150°are identified as preferable for enhanced power output,whereasθ=170°–180°is better suited for optimizing efficiency and stability.These results provide good insights into the design and optimization of pipeline energy harvesting systems for industrial applications.展开更多
The intrinsic strains at the confinement interface of iron carbide with graphene play important roles in the catalytic Fischer-Tropsch synthesis.In this study,we performed theoretical study of the biaxial strain effec...The intrinsic strains at the confinement interface of iron carbide with graphene play important roles in the catalytic Fischer-Tropsch synthesis.In this study,we performed theoretical study of the biaxial strain effects on the CO adsorption and dissociation on the Fe_(2)C(121)surface covered by graphene(Fe_(2)C@graphene).By varying the lattice strains within a range of±5%,the apparent energy barriers(E_(a,app))correlate with the adsorption energies(E_(ad))in nonlinear scaling relations for the direct and H-assisted CO dissociation at the Fe_(2)C active sites,which is normal Br∅nsted-Evans-Polanyi relation for those at the graphene sites.The nonlinear scaling relations can be interpreted by the strain effects on the confinement distances in the adsorption and transition states.This study provides a deep understanding of the intrinsic strain effects of Fe_(2)C@graphene for CO activation.展开更多
Confinement effect is an effective method to enhance carbon dioxide(CO_(2))solubility.In this study,a hybrid sorbent of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([Hmim][NTf_2])/mesoporous titanium ...Confinement effect is an effective method to enhance carbon dioxide(CO_(2))solubility.In this study,a hybrid sorbent of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([Hmim][NTf_2])/mesoporous titanium dioxide(M-TiO_(2))/water(H_2O)was developed,and its confinement effect was regulated by changing the pore structure of M-TiO_(2).CO_(2) solubility in the hybrid sorbent was measured experimentally,and the thermodynamic properties including Henry's constant and desorption enthalpy were calculated.Furthermore,the confinement effect in the hybrid sorbent was quantified.Additionally,the hybrid sorbent was recycled with a multi-cycle experiment.The results showed that M-TiO_(2) calcined at 773.2 K(MT500)could lead to an efficient confinement effect.CO_(2) solubility in the hybrid sorbent increased by 49.8%compared to that of H_2O when the mass fraction of[Hmim][NTf_2]/MT500 was 5.0%(mass),where the contribution of confinement effect on Gibbs free energy occupied 5.2%.展开更多
Currently,simultaneous regulation of external morphology and internal electronic structure for Na_(3)V_(2)(PO_(4))_(3)(NVP)is rarely realized.Herein,complexes of β-cyclodextrin(βCD)and ethylenediaminetetraacetic aci...Currently,simultaneous regulation of external morphology and internal electronic structure for Na_(3)V_(2)(PO_(4))_(3)(NVP)is rarely realized.Herein,complexes of β-cyclodextrin(βCD)and ethylenediaminetetraacetic acid ferric sodium salt(EDTAFeNa)are utilized for the one-step preparation of NVP with spherical morphology as well as Fe substitution.βCD is initially hydrolyzed into glucose,and then carbon microspheres with numerous pores are formed through continuous dehydration and carbonization.The intermediate hydroxymethylfurfural is rich in active functional groups,which are attractive for the V/P-contained raw materials.Accordingly,the nucleation sites for NVP are successfully limited in the spherical framework,possessing a superior surface area of 97.15 g m^(-2).Furthermore,the beneficial Fe in EDTAFeNa enters into the NVP bulk to construct a novel Fe-doped Na_(3)V_(1.95)Fe_(0.05)(PO_(4))_(3)(NVP/β-ISC)material.Fe-substitution induces significant optimizations of electronic structure for NVP,which has been verified by the newly generated abundant oxygen vacancies and extended V-O bond length.Moreover,a multielectron reaction is activated,resulting from the V^(4+)/V^(5+)redox couple.The charge compensation mechanism of NVP/β-ISC is also deeply investigated.Density functional theory(DFT)calculations theoretically elaborate the mechanism of Fe-doping.Consequently,NVP/β-ISC reveals superior sodium storage performance in both half and full cells and even at different extreme conditions(needling,soaking,bending,and freezing).展开更多
Considering the dielectric confinement effect on excitonics of PbSe quantum dots （QDs）, a correction factor in the wave function was introduced to propose a new band gap calculation model for QDs. The modified model...Considering the dielectric confinement effect on excitonics of PbSe quantum dots （QDs）, a correction factor in the wave function was introduced to propose a new band gap calculation model for QDs. The modified model showed great consistency with the experimental data, especially in small size range. According to the variation of confined barrier, the band gap calculation model of PbSe QDs was analyzed in different solvents. The calculating results showed that the modified model was almost solvent-independent, which was consistent with our experimental results and related reports.展开更多
The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunction...The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunctional TiSn‐Beta zeolite was prepared by a simple and scalable post‐synthesis approach,and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2‐diols.The isolated Ti and Sn Lewis acid sites within the TiSn‐Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one‐step conversion of alkenes to 1,2‐diols with a high selectivity of>90%.Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product.Further,the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.展开更多
To mitigate the massive volume expansion of Si-based anode during the charge/discharge cycles,we synthesized a superstructure of Si@Co±NC composite via the carbonization of zeolite imidazolate frameworks incorpor...To mitigate the massive volume expansion of Si-based anode during the charge/discharge cycles,we synthesized a superstructure of Si@Co±NC composite via the carbonization of zeolite imidazolate frameworks incorporated with Si nanoparticles.The Si@Co±NC is comprised of Sinanoparticle core and N-doped/Co-incorporated carbon shell,and there is void space between the core and the shell.When using as anode material for LIBs,Si@Co±NC displayed a super performance with a charge/discharge capacity of 191.6/191.4 mA h g^(-1)and a coulombic efficiency of 100.1%at 1000 mA g^(-1)after 3000 cycles,and the capacity loss rate is 0.022%per cycle only.The excellent electrochemical property of Si@Co±NC is because its electronic conductivity is enhanced by doping the carbon shell with N atoms and by incorporating with Co particles,and the pathway of lithium ions transmission is shortened by the hollow structure and abundant mesopores in the carbon shell.Also,the volume expansion of Si nanoparticles is well accommodated in the void space and suppressed by the carbon host matrix.This work shows that,through designing a superstructure for the anode materials,we can synergistically reduce the work function and introduce the confinement effect,thus significantly enhancing the anode materials’electrochemical performance in LIBs.展开更多
The fundamental momentum conservation requirement q - 0 for the Raman process is relaxed in the nanocrystal- lites （NCs）, and phonons away from the Brillouin-zone center will be involved in the Raman scattering, whi...The fundamental momentum conservation requirement q - 0 for the Raman process is relaxed in the nanocrystal- lites （NCs）, and phonons away from the Brillouin-zone center will be involved in the Raman scattering, which is well-known as the phonon confinement effect in NCs. This usually gives a downshift and asymmetric broadening of the Raman peak in various NCs. Recently, the A1 mode of 1L MoS2 NCs is found to exhibit a blue shift and asymmetric broadening toward the high-frequency side [Chem. Soc. Rev. 44 （2015） 2757 and Phys. Rev. B 91 （2015） 195411]. In this work, we carefully check this issue by studying Raman spectra of lL MoS2 NCs prepared by the ion implantation technique in a wide range of ion-implanted dosage. The same confinement coefficient is used for both E＇ and A＇1 modes in 1L MoS2 NCs since the phonon uncertainty in an NC is mainly determined by its domain size. The asymmetrical broadening near the A＇1 and E＇ modes is attributed to the appearance of defect-activated phonons at the zone edge and the intrinsic asymmetrical broadening of the two modes, where the anisotropy of phonon dispersion curves along Г-K and Г- M is also considered. The photoluminescence spectra confirm the formation of small domain size of 1L MoS2 nanocrystallites in the ion-implanted 1L MoS2. This study provides not only an approach to quickly probe phonon dispersion trends of 2D materials away from Г by the Raman scattering of the corresponding NCs, but also a reference to completely understand the confinement effect of different modes in various nanomaterials.展开更多
The yttria-stabilized zirconia(YSZ)is a famous thermal barrier coating material to protect hot-end components of an engine.As a characteristic feature of the YSZ,the surface roughness shall play an important role in t...The yttria-stabilized zirconia(YSZ)is a famous thermal barrier coating material to protect hot-end components of an engine.As a characteristic feature of the YSZ,the surface roughness shall play an important role in the interface thermal conductance between the YSZ and gas,considering that the gas is typically at an extremely high temperature.We investigate the effect of the surface roughness on the thermal conductance of the YSZ-gas interface with surface roughness described by nanoscale pores on the surface of the YSZ.We reveal two competitive mechanisms related to the microstructure of the pore,i.e.,the actual contact area effect and the confinement effect.The increase of the pore depth will enlarge the actual contact area between the YSZ and gas,leading to enhancement of the solid-gas interface thermal conductance.In contrast to the positive actual contact area effect,the geometry-induced confinement effect greatly reduces the interface thermal conductance.These findings shall offer some fundamental understandings for the microscopic mechanisms of the YSZ-gas interface thermal conductance.展开更多
The main aim of this paper is to discuss the confinement effects on the optical and acoustic phonon vibrational modes in gallium phosphide（GaP） nanoparticles（cylindric grain）.The Raman scattering from the GaP nano...The main aim of this paper is to discuss the confinement effects on the optical and acoustic phonon vibrational modes in gallium phosphide（GaP） nanoparticles（cylindric grain）.The Raman scattering from the GaP nanoparticles was investigated.It was found that the red-shifts of the longitudinal optical（LO） mode and transverse optical（TO） mode were 15 cm？1 and 13.8 cm？1,respectively.It is generally accepted that the red-shifts of the optical phonon modes are due to the presence of smaller nanosized particles（～1.2 nm） acting as the nanoclustered building blocks of the GaP nanoparticles.In the low frequency Raman spectrum,a set of Stokes lines with almost the same spacing was clearly observed.The scattering feature originates from the discrete phonon density of states of the nanoclustered building blocks.According to Lamb＇s vibrational theory,the Raman shift wavenumbers of the spheroidal mode and torsional mode of the lowest energy surface modes for the nanoclustered building blocks were calculated.Good agreement can be achieved between the calculated results and the observed scattering peaks.These results indicate that the corresponding Raman peaks are due to scattering from the localized acoustic phonons in the nanoclustered building blocks in the GaP nanoparticles.展开更多
Natural enzymes,such as horseradish peroxidase(HRP),are a class of important biocatalysts with the high specificity,but their catalytic efficiency is usually unsatisfactory.Thus,the higher catalytic efficiency induced...Natural enzymes,such as horseradish peroxidase(HRP),are a class of important biocatalysts with the high specificity,but their catalytic efficiency is usually unsatisfactory.Thus,the higher catalytic efficiency induced by the confinement effect is promising in optical sensing systems.In this work,a dark-field light scattering sensing platform was fabricated by the confinement effect of HRP from hybridization chain reaction(HCR)and then released to solution by the toehold-mediated strand displacement reaction(TSDR).Then,HRP catalyzed the 3,3,5,5-tetramethylbenzidine(TMB)to TMB^(2+)with the assistance of hydrogen peroxide,which etched the gold nanorods(Au NRs)with the weakened light scattering.The single-particle assay was established based on the decreased light scattering intensity of AuNRs under dark-field microscope.The proposed assay revealed excellent analytical performance within a linear range from 25 pmol/L to 600 pmol/L,and a low limit of detection of 3.12 pmol/L.Additionally,it also manifested satisfactory recovery of mi RNA-21 in human serum samples.The high sensitivity,excellent specificity,and universal applicability make this sensing platform promising for disease diagnosis.展开更多
The supramolecular F?rster resonance energy transfer(FRET)is seen as a promising approach for organic photocatalysis using dyes as catalysts,because it combines the high efficiency of energy transfer with the dynamic ...The supramolecular F?rster resonance energy transfer(FRET)is seen as a promising approach for organic photocatalysis using dyes as catalysts,because it combines the high efficiency of energy transfer with the dynamic responsiveness based on non-covalent interactions.Here we propose a supramolecular FRET photocatalysis strategy forα-oxyamination reaction based on supramolecular confinement effect.The well-designed benzothiadiazole-based cationic monomer as energy donor and the dyes of Nile Red as acceptor are doped into the amphiphilic surfactants of sodium dodecyl sulfate(SDS).Benefitting from the supramolecular confinement space provided by SDS in aqueous environment,the FRET process between the monomer and Nile Red is effectively achieved(exciton migration rate:3.99×10^(14)L mol^(-1)s^(-1)).On this basis,the supramolecular FRET system is used as an efficient energy source to catalyzeα-oxyamination reactions between a series of 1,3-dicarbonyl compounds and 2,2,6,6-tetramethylpiperidine-1-oxyl under white LED light,showing a yield as high as 94%and a turnover frequency value of 3.92 h^(-1).This photocatalytic result shows a great enhancement compared to that of Nile Red alone.展开更多
We present findings on the effect of nanometer-sized silica-based pores on the glass transition of aqueous solutions of lithium bis(trifluoromethane)sulfonimide(LiTFSI)and lithium difluorosulfimide(LiFSI),respectively...We present findings on the effect of nanometer-sized silica-based pores on the glass transition of aqueous solutions of lithium bis(trifluoromethane)sulfonimide(LiTFSI)and lithium difluorosulfimide(LiFSI),respectively.Our experimental results demonstrate a clear dependence of the confinement effect on the anion type,particularly for water-rich solutions,in which the precipitation of crystalized ice under cooling process induces the formation of freeze-concentrated phase confined between pore wall and core ice.As this liquid layer becomes thinner,the freeze-concentrated phase experiences glass transition at increasingly higher temperatures in solutions of LiTFSI.However,differently,for solutions of LiFSI and LiCl,this secondary confinement has a negligible effect on the glass transition of solutions confined wherein.These different behaviors emphasize the obvious difference in the dynamic properties’response of LiTFSI and LiFSI solutions to spatial confinement and particularly to the presence of the hydrophilic pore wall.展开更多
We have measured the variation of photoluminescence(PL) in porous silicon with anodization(AO) time,HF soak time or natural oxidation time,and found that the peak value of PL spectrum will shift towards shorter value ...We have measured the variation of photoluminescence(PL) in porous silicon with anodization(AO) time,HF soak time or natural oxidation time,and found that the peak value of PL spectrum will shift towards shorter value as above time is increased.The analyses in experiment and theory show that the quantum confined structures produced by the AO process may be responsible for the blue shift.展开更多
The wedge-shaped and leaf-type silicon light-emitting devices(LED)are designed and fabricated with the Singapore Chartered Semi Inc.'s dual-gate standard 0.35μm CMOS process.The basic structure of the two devices...The wedge-shaped and leaf-type silicon light-emitting devices(LED)are designed and fabricated with the Singapore Chartered Semi Inc.'s dual-gate standard 0.35μm CMOS process.The basic structure of the two devices is N well-P+ junction.P+ area is the wedge-shaped structure,which is embedded in N well.The leaf-type silicon LED device is a combination of the three wedge-shaped LED devices.The main difference between the two devices is their different electrode distribution,which is mainly in order to analyze the application of electric field confinement(EFC).The devices' micrographs were measured with the Olympus IC test microscope.The forward and reverse bias electrical characteristics of the devices were tested.Light measurements of the devices show that the electrode layout is very important when the electric field confinement is applied.展开更多
Based on the phenomenon that acoustic emissions (AE) generated by rock mass increase suddenly because of underground excavation, time sequence of AE rate in rock failure has been discussed by using statistical damage ...Based on the phenomenon that acoustic emissions (AE) generated by rock mass increase suddenly because of underground excavation, time sequence of AE rate in rock failure has been discussed by using statistical damage theory. It has been demonstrated that how the influence of confining pressure on the deformation behavior and AE characteristics in rocks can be inferred from a simple mechanics model. The results show that loading confining pressure sharply brings out increasing of AE. On the other hand, few AE emits when confining pressure is loaded sharply, and AE occurs again when axial pressure keeps on increasing. These results have been well simulated with computer and show close correspondence with directly measured curves in experiments.展开更多
In order to clarify the edge and interface effect on the adhesion energy between graphene(Gr)and its substrate,a theoretical model is proposed to study the interaction and strain distribution of Gr/Si system in terms ...In order to clarify the edge and interface effect on the adhesion energy between graphene(Gr)and its substrate,a theoretical model is proposed to study the interaction and strain distribution of Gr/Si system in terms of continuum medium mechanics and nanothermodynamics.We find that the interface separation and adhesion energy are determined by the thickness of Gr and substrate.The disturbed interaction and redistributed strain in the Gr/Si system induced by the effect of surface and interface can make the interface adhesion energy decrease with increasing thickness of Gr and diminishing thickness of Si.Moreover,our results show that the smaller area of Gr is more likely to adhere to the substrate since the edge effect improves the active energy and strain energy.Our predictions can be expected to be a guide for designing high performance of Grbased electronic devices.展开更多
The quantum confinement effect fundamentally alters the optical and electronic properties of quantum dots(QDs),making them versatile building blocks for next-generation light-emitting diodes(LEDs).This study investiga...The quantum confinement effect fundamentally alters the optical and electronic properties of quantum dots(QDs),making them versatile building blocks for next-generation light-emitting diodes(LEDs).This study investigates how quantum confinement governs the charge transport,exciton dynamics,and emission efficiency in QD-LEDs,using CsPbI_(3) QDs as a model system.By systematically varying QD sizes,we reveal size-dependent trade-offs in LED performance,such as enhanced efficiency for smaller QDs but increased brightness and stability for larger QDs under high current densities.Our findings offer critical insights into the design of high-performance QD-LEDs,paving the way for scalable and energy-efficient optoelectronic devices.展开更多
Single-molecule junctions are building blocks for constructing molecular devices.However,intermolecular interactions like winding bring additional interference among the surrounding molecules,which inhibits the intrin...Single-molecule junctions are building blocks for constructing molecular devices.However,intermolecular interactions like winding bring additional interference among the surrounding molecules,which inhibits the intrinsic coherent transport through single-molecule junctions.Here,we employed a nanocavity(dimethoxypillar[5]arene,DMP[5]),which is analogous to electric cables,to confine the conformation of flexible chains(1,8-diaminooctane,DAO)via host-vip interaction.Single-molecule conductance measurements indicate that the conductance of DAO encapsulated with DMP[5]is as high as that of pure DAO,as reproduced by theoretical simulations.Intriguingly,the molecular lengths of the DAO encapsulated with DMP[5]increase from 1.13 nm to 1.46 nm compared with the pure DAO,indicating that DMP[5]keeps DAO upright-standing via the confinement effect.This work provides a new strategy to decouple the intermolecular interaction by employing an insulating sheath,enabling the high-density integration of single-molecule devices.展开更多
基金supported by the Postgraduate Education Reform Project of Shandong Province(SDYAL2023032)the National Key Research and Development Program(2021YFB3500102)。
文摘Multidimensional confined structure systems are proposed and demonstrated by using MoO_(2)@MO_(2)C(MMC)to enhance the photothermal catalytic performance of the metal sulfides-multidimensional confined structure(TMs-MDCS).Specifically,the MMC nanoparticles confined to the surface of the ZnIn_(2)S_(4)hollow tube-shell(MMC/HT-ZIS)achieve a hydrogen evolution rate of 9.72 mmol g^(-1)h^(-1),which is 11.2 times higher than that of pure HT-ZIS.Meanwhile,the MnCdS(MCS)nanoparticles are encapsulated within the two-dimensional MMC(2D MMC/MCS)through precise regulation of size and morphology.The 10-MMC/MCS lamellar network demonstrates the highest hydrogen evolution rate of 8.19 mmol g^(-1)-h^(-1).The obtained MMC/TMs-MDCS catalysts exhibit an enhanced photocatalytic hydrogen evolution rate,which can be attributed to the strong synergistic interaction between the multidimensional confinement and the photothermal effects.The confinement space and the strong interfacial relationship within the MMC/TMs-MDCS create abundant channels and active sites that facilitate electron migration and transport.Furthermore,the construction of a confined environment positions these materials as promising candidates for achieving exceptional photothermal catalytic performance,as MMC/TMs-MDCS enhance light absorption through light scattering and reflecting effects.Additionally,the capacity of MMC/TMsMDCS to convert solar light into thermal energy significantly reduces the activation energy of the reaction,thereby facilitating reaction kinetics and accelerating the separation and transport of photogenerated carriers.This work provides valuable insights for the development of highly efficient photothermal catalytic water-splitting systems for hydrogen production using multidimensional confined catalysts.
基金supported by the National Natural Science Foundation of China(Grant Nos.52276159,62373270)supported by the Natural Science Foundation of Tianjin(Grant No.23JCQNJC00060)+1 种基金the Scientific Research Program of Tianjin Municipal Education Commission(Grant No.2022KJ065)the Graduate Student Research and Innovation Funding Program of Civil Aviation University of China(Grant No.2024YJSKC02003).
文摘This study addresses the challenge by introducing a piezoelectric energy harvester based on vortex-induced vibration(VIV)and galloping interactions.Experiments on an elastically mounted circular cylinder equipped with two small square rods(SSR)in a DN100 pipe were conducted to examine how the circumferential angle of the SSR impacts the vibration response of cylinder,revealing distinct interaction modes(VIV-only and VIV-galloping interaction).The results show that placing the SSR toward the bluff body’s trailing edge accelerates the onset of galloping at lower velocities.In particular,as the SSR angle is in the range ofθ=160°–180°,the fluid-structure interaction behavior deviates from prior open-flow studies.This difference is attributed to the influence of the pipe wall and is analyzed using the shear layer interaction mode theory.The relationship between SSR placement angles and fluid-induced vibration(FIV)characteristics across various fluid velocities was also mapped,with dynamic influences assessed using the Strouhal number and stability parameterΔS,helping to distinguish between interaction modes.Based on these findings,configurations withθ=50°–70°andθ=140°–150°are identified as preferable for enhanced power output,whereasθ=170°–180°is better suited for optimizing efficiency and stability.These results provide good insights into the design and optimization of pipeline energy harvesting systems for industrial applications.
基金supported by the National Natural Science Foundation of China(21972170,22072184)the Fund for Academic Innovation Teams of South-Central Minzu University(XTZ24013)
文摘The intrinsic strains at the confinement interface of iron carbide with graphene play important roles in the catalytic Fischer-Tropsch synthesis.In this study,we performed theoretical study of the biaxial strain effects on the CO adsorption and dissociation on the Fe_(2)C(121)surface covered by graphene(Fe_(2)C@graphene).By varying the lattice strains within a range of±5%,the apparent energy barriers(E_(a,app))correlate with the adsorption energies(E_(ad))in nonlinear scaling relations for the direct and H-assisted CO dissociation at the Fe_(2)C active sites,which is normal Br∅nsted-Evans-Polanyi relation for those at the graphene sites.The nonlinear scaling relations can be interpreted by the strain effects on the confinement distances in the adsorption and transition states.This study provides a deep understanding of the intrinsic strain effects of Fe_(2)C@graphene for CO activation.
基金the National Natural Science Foundation of China(22108115,22478415,and 21978134)Natural Science Foundation of Jiangsu Province(BK20241744)。
文摘Confinement effect is an effective method to enhance carbon dioxide(CO_(2))solubility.In this study,a hybrid sorbent of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([Hmim][NTf_2])/mesoporous titanium dioxide(M-TiO_(2))/water(H_2O)was developed,and its confinement effect was regulated by changing the pore structure of M-TiO_(2).CO_(2) solubility in the hybrid sorbent was measured experimentally,and the thermodynamic properties including Henry's constant and desorption enthalpy were calculated.Furthermore,the confinement effect in the hybrid sorbent was quantified.Additionally,the hybrid sorbent was recycled with a multi-cycle experiment.The results showed that M-TiO_(2) calcined at 773.2 K(MT500)could lead to an efficient confinement effect.CO_(2) solubility in the hybrid sorbent increased by 49.8%compared to that of H_2O when the mass fraction of[Hmim][NTf_2]/MT500 was 5.0%(mass),where the contribution of confinement effect on Gibbs free energy occupied 5.2%.
基金financially supported by the Key Research and Development(R&D)Projects of Shanxi Province(202202040201005)the Graduate Innovation Project of Shanxi Province(No.2024SJ261)。
文摘Currently,simultaneous regulation of external morphology and internal electronic structure for Na_(3)V_(2)(PO_(4))_(3)(NVP)is rarely realized.Herein,complexes of β-cyclodextrin(βCD)and ethylenediaminetetraacetic acid ferric sodium salt(EDTAFeNa)are utilized for the one-step preparation of NVP with spherical morphology as well as Fe substitution.βCD is initially hydrolyzed into glucose,and then carbon microspheres with numerous pores are formed through continuous dehydration and carbonization.The intermediate hydroxymethylfurfural is rich in active functional groups,which are attractive for the V/P-contained raw materials.Accordingly,the nucleation sites for NVP are successfully limited in the spherical framework,possessing a superior surface area of 97.15 g m^(-2).Furthermore,the beneficial Fe in EDTAFeNa enters into the NVP bulk to construct a novel Fe-doped Na_(3)V_(1.95)Fe_(0.05)(PO_(4))_(3)(NVP/β-ISC)material.Fe-substitution induces significant optimizations of electronic structure for NVP,which has been verified by the newly generated abundant oxygen vacancies and extended V-O bond length.Moreover,a multielectron reaction is activated,resulting from the V^(4+)/V^(5+)redox couple.The charge compensation mechanism of NVP/β-ISC is also deeply investigated.Density functional theory(DFT)calculations theoretically elaborate the mechanism of Fe-doping.Consequently,NVP/β-ISC reveals superior sodium storage performance in both half and full cells and even at different extreme conditions(needling,soaking,bending,and freezing).
文摘Considering the dielectric confinement effect on excitonics of PbSe quantum dots （QDs）, a correction factor in the wave function was introduced to propose a new band gap calculation model for QDs. The modified model showed great consistency with the experimental data, especially in small size range. According to the variation of confined barrier, the band gap calculation model of PbSe QDs was analyzed in different solvents. The calculating results showed that the modified model was almost solvent-independent, which was consistent with our experimental results and related reports.
文摘The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunctional TiSn‐Beta zeolite was prepared by a simple and scalable post‐synthesis approach,and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2‐diols.The isolated Ti and Sn Lewis acid sites within the TiSn‐Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one‐step conversion of alkenes to 1,2‐diols with a high selectivity of>90%.Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product.Further,the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.
基金financial supports by the National Natural Science Foundation of China(No.51772295)support of GTIIT for the collaboration,and the start-up fund provided by GTIIT
文摘To mitigate the massive volume expansion of Si-based anode during the charge/discharge cycles,we synthesized a superstructure of Si@Co±NC composite via the carbonization of zeolite imidazolate frameworks incorporated with Si nanoparticles.The Si@Co±NC is comprised of Sinanoparticle core and N-doped/Co-incorporated carbon shell,and there is void space between the core and the shell.When using as anode material for LIBs,Si@Co±NC displayed a super performance with a charge/discharge capacity of 191.6/191.4 mA h g^(-1)and a coulombic efficiency of 100.1%at 1000 mA g^(-1)after 3000 cycles,and the capacity loss rate is 0.022%per cycle only.The excellent electrochemical property of Si@Co±NC is because its electronic conductivity is enhanced by doping the carbon shell with N atoms and by incorporating with Co particles,and the pathway of lithium ions transmission is shortened by the hollow structure and abundant mesopores in the carbon shell.Also,the volume expansion of Si nanoparticles is well accommodated in the void space and suppressed by the carbon host matrix.This work shows that,through designing a superstructure for the anode materials,we can synergistically reduce the work function and introduce the confinement effect,thus significantly enhancing the anode materials’electrochemical performance in LIBs.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11225421,11474277,11434010 and 11574305the National Young 1000 Talent Plan
文摘The fundamental momentum conservation requirement q - 0 for the Raman process is relaxed in the nanocrystal- lites （NCs）, and phonons away from the Brillouin-zone center will be involved in the Raman scattering, which is well-known as the phonon confinement effect in NCs. This usually gives a downshift and asymmetric broadening of the Raman peak in various NCs. Recently, the A1 mode of 1L MoS2 NCs is found to exhibit a blue shift and asymmetric broadening toward the high-frequency side [Chem. Soc. Rev. 44 （2015） 2757 and Phys. Rev. B 91 （2015） 195411]. In this work, we carefully check this issue by studying Raman spectra of lL MoS2 NCs prepared by the ion implantation technique in a wide range of ion-implanted dosage. The same confinement coefficient is used for both E＇ and A＇1 modes in 1L MoS2 NCs since the phonon uncertainty in an NC is mainly determined by its domain size. The asymmetrical broadening near the A＇1 and E＇ modes is attributed to the appearance of defect-activated phonons at the zone edge and the intrinsic asymmetrical broadening of the two modes, where the anisotropy of phonon dispersion curves along Г-K and Г- M is also considered. The photoluminescence spectra confirm the formation of small domain size of 1L MoS2 nanocrystallites in the ion-implanted 1L MoS2. This study provides not only an approach to quickly probe phonon dispersion trends of 2D materials away from Г by the Raman scattering of the corresponding NCs, but also a reference to completely understand the confinement effect of different modes in various nanomaterials.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11822206 and 12072182)the Innovation Program of the Shanghai Municipal Education Commission(Grant No.2017-01-07-00-09-E00019)+1 种基金the Key Research Project of Zhejiang Laboratorythe National Supercomputing Center in Zhengzhou(Grant No.2021PE0AC02)
文摘The yttria-stabilized zirconia(YSZ)is a famous thermal barrier coating material to protect hot-end components of an engine.As a characteristic feature of the YSZ,the surface roughness shall play an important role in the interface thermal conductance between the YSZ and gas,considering that the gas is typically at an extremely high temperature.We investigate the effect of the surface roughness on the thermal conductance of the YSZ-gas interface with surface roughness described by nanoscale pores on the surface of the YSZ.We reveal two competitive mechanisms related to the microstructure of the pore,i.e.,the actual contact area effect and the confinement effect.The increase of the pore depth will enlarge the actual contact area between the YSZ and gas,leading to enhancement of the solid-gas interface thermal conductance.In contrast to the positive actual contact area effect,the geometry-induced confinement effect greatly reduces the interface thermal conductance.These findings shall offer some fundamental understandings for the microscopic mechanisms of the YSZ-gas interface thermal conductance.
文摘The main aim of this paper is to discuss the confinement effects on the optical and acoustic phonon vibrational modes in gallium phosphide（GaP） nanoparticles（cylindric grain）.The Raman scattering from the GaP nanoparticles was investigated.It was found that the red-shifts of the longitudinal optical（LO） mode and transverse optical（TO） mode were 15 cm？1 and 13.8 cm？1,respectively.It is generally accepted that the red-shifts of the optical phonon modes are due to the presence of smaller nanosized particles（～1.2 nm） acting as the nanoclustered building blocks of the GaP nanoparticles.In the low frequency Raman spectrum,a set of Stokes lines with almost the same spacing was clearly observed.The scattering feature originates from the discrete phonon density of states of the nanoclustered building blocks.According to Lamb＇s vibrational theory,the Raman shift wavenumbers of the spheroidal mode and torsional mode of the lowest energy surface modes for the nanoclustered building blocks were calculated.Good agreement can be achieved between the calculated results and the observed scattering peaks.These results indicate that the corresponding Raman peaks are due to scattering from the localized acoustic phonons in the nanoclustered building blocks in the GaP nanoparticles.
基金financial supported from the National Natural Science Foundation of China(No.22174115)the Graduate Education and Teaching Reform Research Project of Chongqing(No.yjg223038)the Fundamental Research Funds for the Central Universities(No.SWU-XDJH202321)。
文摘Natural enzymes,such as horseradish peroxidase(HRP),are a class of important biocatalysts with the high specificity,but their catalytic efficiency is usually unsatisfactory.Thus,the higher catalytic efficiency induced by the confinement effect is promising in optical sensing systems.In this work,a dark-field light scattering sensing platform was fabricated by the confinement effect of HRP from hybridization chain reaction(HCR)and then released to solution by the toehold-mediated strand displacement reaction(TSDR).Then,HRP catalyzed the 3,3,5,5-tetramethylbenzidine(TMB)to TMB^(2+)with the assistance of hydrogen peroxide,which etched the gold nanorods(Au NRs)with the weakened light scattering.The single-particle assay was established based on the decreased light scattering intensity of AuNRs under dark-field microscope.The proposed assay revealed excellent analytical performance within a linear range from 25 pmol/L to 600 pmol/L,and a low limit of detection of 3.12 pmol/L.Additionally,it also manifested satisfactory recovery of mi RNA-21 in human serum samples.The high sensitivity,excellent specificity,and universal applicability make this sensing platform promising for disease diagnosis.
基金financially supported by the National Natural Science Foundation of China (Nos.22371230,22022107,22001213,and 22071197)the Postdoctoral Science Foundation of China (Nos.2023M732855,2022TQ0258)the Shaanxi Fundamental Science Research Project for Chemistry & Biology (No.22JHQ020)。
文摘The supramolecular F?rster resonance energy transfer(FRET)is seen as a promising approach for organic photocatalysis using dyes as catalysts,because it combines the high efficiency of energy transfer with the dynamic responsiveness based on non-covalent interactions.Here we propose a supramolecular FRET photocatalysis strategy forα-oxyamination reaction based on supramolecular confinement effect.The well-designed benzothiadiazole-based cationic monomer as energy donor and the dyes of Nile Red as acceptor are doped into the amphiphilic surfactants of sodium dodecyl sulfate(SDS).Benefitting from the supramolecular confinement space provided by SDS in aqueous environment,the FRET process between the monomer and Nile Red is effectively achieved(exciton migration rate:3.99×10^(14)L mol^(-1)s^(-1)).On this basis,the supramolecular FRET system is used as an efficient energy source to catalyzeα-oxyamination reactions between a series of 1,3-dicarbonyl compounds and 2,2,6,6-tetramethylpiperidine-1-oxyl under white LED light,showing a yield as high as 94%and a turnover frequency value of 3.92 h^(-1).This photocatalytic result shows a great enhancement compared to that of Nile Red alone.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974385 and 91956101).
文摘We present findings on the effect of nanometer-sized silica-based pores on the glass transition of aqueous solutions of lithium bis(trifluoromethane)sulfonimide(LiTFSI)and lithium difluorosulfimide(LiFSI),respectively.Our experimental results demonstrate a clear dependence of the confinement effect on the anion type,particularly for water-rich solutions,in which the precipitation of crystalized ice under cooling process induces the formation of freeze-concentrated phase confined between pore wall and core ice.As this liquid layer becomes thinner,the freeze-concentrated phase experiences glass transition at increasingly higher temperatures in solutions of LiTFSI.However,differently,for solutions of LiFSI and LiCl,this secondary confinement has a negligible effect on the glass transition of solutions confined wherein.These different behaviors emphasize the obvious difference in the dynamic properties’response of LiTFSI and LiFSI solutions to spatial confinement and particularly to the presence of the hydrophilic pore wall.
文摘We have measured the variation of photoluminescence(PL) in porous silicon with anodization(AO) time,HF soak time or natural oxidation time,and found that the peak value of PL spectrum will shift towards shorter value as above time is increased.The analyses in experiment and theory show that the quantum confined structures produced by the AO process may be responsible for the blue shift.
基金National Natural Science Foundation Subject(60536030,60676038)Tianjin Key Basic Research Project(06YFJZJC00200)
文摘The wedge-shaped and leaf-type silicon light-emitting devices(LED)are designed and fabricated with the Singapore Chartered Semi Inc.'s dual-gate standard 0.35μm CMOS process.The basic structure of the two devices is N well-P+ junction.P+ area is the wedge-shaped structure,which is embedded in N well.The leaf-type silicon LED device is a combination of the three wedge-shaped LED devices.The main difference between the two devices is their different electrode distribution,which is mainly in order to analyze the application of electric field confinement(EFC).The devices' micrographs were measured with the Olympus IC test microscope.The forward and reverse bias electrical characteristics of the devices were tested.Light measurements of the devices show that the electrode layout is very important when the electric field confinement is applied.
文摘Based on the phenomenon that acoustic emissions (AE) generated by rock mass increase suddenly because of underground excavation, time sequence of AE rate in rock failure has been discussed by using statistical damage theory. It has been demonstrated that how the influence of confining pressure on the deformation behavior and AE characteristics in rocks can be inferred from a simple mechanics model. The results show that loading confining pressure sharply brings out increasing of AE. On the other hand, few AE emits when confining pressure is loaded sharply, and AE occurs again when axial pressure keeps on increasing. These results have been well simulated with computer and show close correspondence with directly measured curves in experiments.
基金This work was supported by the Natural Science Foundation of Guangdong Province(Grant Nos.2019A1515010916 and 2018A030307028)the Featured Innovation Project of Guangdong Education Department(2018KTSCX150)+1 种基金the Maoming Natural Science Foundation of Guangdong,China,(Grant No.2019018001)the Guangdong Province Major Foundation of Fundamental Research(Grant No.517042).
文摘In order to clarify the edge and interface effect on the adhesion energy between graphene(Gr)and its substrate,a theoretical model is proposed to study the interaction and strain distribution of Gr/Si system in terms of continuum medium mechanics and nanothermodynamics.We find that the interface separation and adhesion energy are determined by the thickness of Gr and substrate.The disturbed interaction and redistributed strain in the Gr/Si system induced by the effect of surface and interface can make the interface adhesion energy decrease with increasing thickness of Gr and diminishing thickness of Si.Moreover,our results show that the smaller area of Gr is more likely to adhere to the substrate since the edge effect improves the active energy and strain energy.Our predictions can be expected to be a guide for designing high performance of Grbased electronic devices.
基金support from the National Key Research and Development Program of China(2024YFA1207700)National Natural Science Foundation of China(52072141,52102170).
文摘The quantum confinement effect fundamentally alters the optical and electronic properties of quantum dots(QDs),making them versatile building blocks for next-generation light-emitting diodes(LEDs).This study investigates how quantum confinement governs the charge transport,exciton dynamics,and emission efficiency in QD-LEDs,using CsPbI_(3) QDs as a model system.By systematically varying QD sizes,we reveal size-dependent trade-offs in LED performance,such as enhanced efficiency for smaller QDs but increased brightness and stability for larger QDs under high current densities.Our findings offer critical insights into the design of high-performance QD-LEDs,paving the way for scalable and energy-efficient optoelectronic devices.
基金supported by the National Natural Science Foundation of China(Nos.22205084,42307566,22325303,22250003,T2222002,21991130,22032004)Fujian Provincial Natural Science Foundation of China(No.2022H6014)+4 种基金the China Postdoctoral Science Foundation(Nos.2023M741039,2023M742199)Project funded by National&Local Joint Engineering Research Center for Mineral Salt Deep Utilization(No.SF202303)State Key Laboratory of Efficient Utilization for Low Grade Phosphate Rock and Its Associated Resources WFKF(2023)013the Fundamental Research Funds for the Central Universities(Xiamen University,No.20720240053)State Key Laboratory of Vaccines for Infectious Diseases,Xiang An Biomedicine Laboratory(No.2023XAKJ0103074)。
文摘Single-molecule junctions are building blocks for constructing molecular devices.However,intermolecular interactions like winding bring additional interference among the surrounding molecules,which inhibits the intrinsic coherent transport through single-molecule junctions.Here,we employed a nanocavity(dimethoxypillar[5]arene,DMP[5]),which is analogous to electric cables,to confine the conformation of flexible chains(1,8-diaminooctane,DAO)via host-vip interaction.Single-molecule conductance measurements indicate that the conductance of DAO encapsulated with DMP[5]is as high as that of pure DAO,as reproduced by theoretical simulations.Intriguingly,the molecular lengths of the DAO encapsulated with DMP[5]increase from 1.13 nm to 1.46 nm compared with the pure DAO,indicating that DMP[5]keeps DAO upright-standing via the confinement effect.This work provides a new strategy to decouple the intermolecular interaction by employing an insulating sheath,enabling the high-density integration of single-molecule devices.
