Photocatalytic oxygen(O_(2))reduction has been considered a promising method for hydrogen peroxide(H_(2)O_(2))production.However,the poor visible light harvesting and low-efficient separation and generation of charge ...Photocatalytic oxygen(O_(2))reduction has been considered a promising method for hydrogen peroxide(H_(2)O_(2))production.However,the poor visible light harvesting and low-efficient separation and generation of charge carriers of conventional photocatalysts strongly limited their photocatalytic H_(2)O_(2) generation performance.Herein,we design a highly efficient photocatalyst in this work by marrying luminescent gold-silver nanoclusters(AuAg NCs)to polyethyleneimine(PEI)modified C_(3)N_(4)(C3N4-PEI).The key design in this work is the utilization of highly luminescent AuAg NCs as photosensitizers to promote the generation and separation of charge carriers of C_(3)N_(4)-PEI,thereby ultimately producing abundant e−for O_(2) reduction under visible light illumination(λ≥400 nm).As a result,the as-designed photocatalyst(C3N4-PEI-AuAg NCs)exhibits excellent photocatalytic activity with an H_(2)O_(2) production capability of 82μM in pure water,which is 3.5 times higher than pristine C_(3)N_(4)(23μM).This interesting design provides a paradigm in developing other high-efficient photocatalysts for visible-light-driven H_(2)O_(2) production.展开更多
Part of the tunnel spoil can not be used for concrete due to alkali aggregate reaction(AAR).Water is an indis-pensable condition for AAR,so separating the alkali-aggregate from water is of great benefit to controlling...Part of the tunnel spoil can not be used for concrete due to alkali aggregate reaction(AAR).Water is an indis-pensable condition for AAR,so separating the alkali-aggregate from water is of great benefit to controlling the AAR.This paper investigates the modification of concrete and aggregate by hydrophobic impregnation and organic coating and then evaluates their waterproof and me chanical properties by dynamic contact angle(DCA),ultrasonic wave velocity,scanning electron microscope(SEM),nuclear magnetic resonance(NMR),and so on.For waterproofness,hydrophobic impregnation and organic coating can both improve the waterproof-ness of concrete and aggregate.The organic coating is suitable for aggregate because it wrap aggregate well.And aggregate coated by PVA can improve the interfacial transition zone(ITZ).For mechanical properties,both mate-rials will weaken the strength of the interface.Furthermore,concrete made by aggregate with organic coating shows plastic deformation and has a good correlation with the film thickness,a plastic estimation model based on flm thickness is proposed.This paper evaluates the waterproof of concrete and aggregate and finds plastic con-crete with good aggregate waterproofness which provides a new idea for the application of alkali aggregate in see-page control facilities of water conservancy projects.展开更多
Flame features and dynamics are important to the explanation and prediction of a lean blowout(LBO)phenomenon.In this paper,recognition of near-LBO flame features and oscillation characterization methods were proposed ...Flame features and dynamics are important to the explanation and prediction of a lean blowout(LBO)phenomenon.In this paper,recognition of near-LBO flame features and oscillation characterization methods were proposed based on flame spectroscopic images.High-speed planar laser-induced fluorescence measurements of OH were used to capture unique dynamic features such as the local extinction and reignition feature and entrained reactant pockets.The Zernike moment demonstrated a good performance in recognition of stability and near-LBO conditions,though the geometric moment had more advantages to characterize frequency characteristics.Low-frequency oscillations,especially at the obvious self-excited oscillation frequency around 200 Hz,were found when approaching an LBO condition,which can be expected to be used as a novel prediction characteristic parameter of the flameout limit.Proper orthogonal decomposition(POD)and dynamic mode decomposition(DMD)were used to conduct dynamic analysis of near-LBO flames.POD modes spectra showed the unique frequency characteristics of stable and near-LBO flames,which were basically in line with those at the heat-release frequency.The primary POD modes demonstrated that the radial vibration mode dominated in a stable flame,while the rotation mode was found to exist in a near-LBO flame.Analysis of modal decomposition showed that flame shedding and agminated entrained reactant pockets were responsible for generating self-excited flame oscillations.展开更多
Cu(I)-catalyzed azide-alkyne cycloadditions(CuAAC)have gained increasing interest in the selective labeling of living cells and organisms with biomolecules.However,their application is constrained either by the high c...Cu(I)-catalyzed azide-alkyne cycloadditions(CuAAC)have gained increasing interest in the selective labeling of living cells and organisms with biomolecules.However,their application is constrained either by the high cytotoxicity of Cu(I)ions or the low activity of CuAAC in the internal space of living cells.This paper reports the design of a novel Cu-based nanocatalyst,watersoluble thiolated Cu30 nanoclusters(NCs),for living cell labeling via CuAAC.The Cu30 NCs offer good biocompatibility,excellent stability,and scalable synthesis(e.g.,gram scale),which would facilitate potential commercial applications.By combining the highly localized Cu(I)active species on the NC surface and good structural stability,the Cu30 NCs exhibit superior catalytic activities for a series of Huisgen cycloaddition reactions with good recyclability.More importantly,the biocompatibility of the Cu30 NCs enables them to be a good catalyst for CuAAC,whereby the challenging labeling of living cells can be achieved via CuAAC on the cell membrane.This study sheds light on the facile synthesis of atomically precise Cu NCs,as well as the design of novel Cu NCs-based nanocatalysts for CuAAC in intracellular bioorthogonal applications.展开更多
基金National Natural Science Foundation of China(21908121,22071127)Taishan Scholar Foundation(tsqn201812074,China)Scientific Research Foundation of Qingdao University of Science and Technology(210/010029031,and 210/010029008).
文摘Photocatalytic oxygen(O_(2))reduction has been considered a promising method for hydrogen peroxide(H_(2)O_(2))production.However,the poor visible light harvesting and low-efficient separation and generation of charge carriers of conventional photocatalysts strongly limited their photocatalytic H_(2)O_(2) generation performance.Herein,we design a highly efficient photocatalyst in this work by marrying luminescent gold-silver nanoclusters(AuAg NCs)to polyethyleneimine(PEI)modified C_(3)N_(4)(C3N4-PEI).The key design in this work is the utilization of highly luminescent AuAg NCs as photosensitizers to promote the generation and separation of charge carriers of C_(3)N_(4)-PEI,thereby ultimately producing abundant e−for O_(2) reduction under visible light illumination(λ≥400 nm).As a result,the as-designed photocatalyst(C3N4-PEI-AuAg NCs)exhibits excellent photocatalytic activity with an H_(2)O_(2) production capability of 82μM in pure water,which is 3.5 times higher than pristine C_(3)N_(4)(23μM).This interesting design provides a paradigm in developing other high-efficient photocatalysts for visible-light-driven H_(2)O_(2) production.
基金This work was financially supported by the National Natural Science Foundation of China(52108358)China Postdoctoral Science Foundation(2021M693110)Special Research Associate Project of Chinese Academy of Sciences(E1K2180).
文摘Part of the tunnel spoil can not be used for concrete due to alkali aggregate reaction(AAR).Water is an indis-pensable condition for AAR,so separating the alkali-aggregate from water is of great benefit to controlling the AAR.This paper investigates the modification of concrete and aggregate by hydrophobic impregnation and organic coating and then evaluates their waterproof and me chanical properties by dynamic contact angle(DCA),ultrasonic wave velocity,scanning electron microscope(SEM),nuclear magnetic resonance(NMR),and so on.For waterproofness,hydrophobic impregnation and organic coating can both improve the waterproof-ness of concrete and aggregate.The organic coating is suitable for aggregate because it wrap aggregate well.And aggregate coated by PVA can improve the interfacial transition zone(ITZ).For mechanical properties,both mate-rials will weaken the strength of the interface.Furthermore,concrete made by aggregate with organic coating shows plastic deformation and has a good correlation with the film thickness,a plastic estimation model based on flm thickness is proposed.This paper evaluates the waterproof of concrete and aggregate and finds plastic con-crete with good aggregate waterproofness which provides a new idea for the application of alkali aggregate in see-page control facilities of water conservancy projects.
基金supported by the Heilongjiang Provincial Natural Science Foundation of China(No.LH2021F028)。
文摘Flame features and dynamics are important to the explanation and prediction of a lean blowout(LBO)phenomenon.In this paper,recognition of near-LBO flame features and oscillation characterization methods were proposed based on flame spectroscopic images.High-speed planar laser-induced fluorescence measurements of OH were used to capture unique dynamic features such as the local extinction and reignition feature and entrained reactant pockets.The Zernike moment demonstrated a good performance in recognition of stability and near-LBO conditions,though the geometric moment had more advantages to characterize frequency characteristics.Low-frequency oscillations,especially at the obvious self-excited oscillation frequency around 200 Hz,were found when approaching an LBO condition,which can be expected to be used as a novel prediction characteristic parameter of the flameout limit.Proper orthogonal decomposition(POD)and dynamic mode decomposition(DMD)were used to conduct dynamic analysis of near-LBO flames.POD modes spectra showed the unique frequency characteristics of stable and near-LBO flames,which were basically in line with those at the heat-release frequency.The primary POD modes demonstrated that the radial vibration mode dominated in a stable flame,while the rotation mode was found to exist in a near-LBO flame.Analysis of modal decomposition showed that flame shedding and agminated entrained reactant pockets were responsible for generating self-excited flame oscillations.
基金This work was supported by the National Natural Science Foundation of China(No.22071127)Taishan Scholar Foundation(No.tsqn201812074)+1 种基金the Natural Science Foundation of Shandong Province(No.ZR2019YQ07)the NanoBio Lab(IMRE,A*STAR,Singapore).
文摘Cu(I)-catalyzed azide-alkyne cycloadditions(CuAAC)have gained increasing interest in the selective labeling of living cells and organisms with biomolecules.However,their application is constrained either by the high cytotoxicity of Cu(I)ions or the low activity of CuAAC in the internal space of living cells.This paper reports the design of a novel Cu-based nanocatalyst,watersoluble thiolated Cu30 nanoclusters(NCs),for living cell labeling via CuAAC.The Cu30 NCs offer good biocompatibility,excellent stability,and scalable synthesis(e.g.,gram scale),which would facilitate potential commercial applications.By combining the highly localized Cu(I)active species on the NC surface and good structural stability,the Cu30 NCs exhibit superior catalytic activities for a series of Huisgen cycloaddition reactions with good recyclability.More importantly,the biocompatibility of the Cu30 NCs enables them to be a good catalyst for CuAAC,whereby the challenging labeling of living cells can be achieved via CuAAC on the cell membrane.This study sheds light on the facile synthesis of atomically precise Cu NCs,as well as the design of novel Cu NCs-based nanocatalysts for CuAAC in intracellular bioorthogonal applications.
