Constructing fast mass-transfer channels with efficient catalytic ozonation activity in 2D manganese dioxide membranes by intercalating Fe/Mn bimetallic MOF

Two-dimensional(2D)catalytic ozonation membranes are promising for the treatment of micropollutants in wastewater due to simultaneous ozone-catalyzed degradation and membrane filtration processes.However,it remains challenging for 2D catalytic ozonation membranes to efficiently degrade micropollutants due to low mass-transfer efficiency and poor catalytic activity.Herein,Fe/Mn bimetallic metal-organic framework(MOF)intercalated lamellar MnO_(2) membranes with fast and robust ozone-catalyzed mass-transfer channels were developed on the surface of the hollow fiber ceramic membrane(HFCM)to obtain 2D Fe/Mn-MOF@MnO_(2)-HFCM for efficiently degrading micropollutants in wastewater.The intercalation of Fe/Mn-MOF expanded the interlayer spacing of the MnO_(2) membrane,thereby providing abundant transport channels for rapid passage of water.More notably,the Fe/Mn-MOF provided enriched reactive sites as well as high electron transfer efficiency based on the redox cycling between Mn^(3+)/Mn^(4+) and Fe^(2+)/Fe^(3+),ensuring the effective catalytic oxidative degradation of micropollutants including tetracycline hydrochloride(TCH),methylene blue,and methyl blue.Moreover,the carboxyl groups on the MOF formed covalent bonds(-COO-)with the hydroxyl groups in MnO_(2) between layers,which increased the interaction between MnO_(2) nanosheets to form stable interlayer channels.Specifically,the optimal composite membrane achieved a high removal rate of TCH micropollutant(93.4%),high water treatment capacity(282 L·m^(-2)·h^(-1)·MPa^(-1)),and excellent longterm stability(1200 min).This study provides a simple and easily scalable strategy to construct fast,efficient,and stable 2D catalytic mass-transfer channels for the efficient treatment of micropollutants in wastewater.

Flower-like tin oxide membranes with robust three-dimensional channels for efficient removal of iron ions from hydrogen peroxide

Membrane technology has become the mainstream process for the production of electronic grade hydrogen peroxide(H_(2)O_(2)).But due to the oxidation degradation of the organic membranes(e.g.polyamide)by the strong oxidative radicals(e.g.OH)generated via the activation of H_(2)O_(2)by iron ions(Fe^(3+)),the short effective lifetime of membranes remains a challenge.Inorganic nano tin oxide(SnO_(2))has great potential for the removal of Fe^(3+)in strongly oxidative H_(2)O_(2)because of its ability to stabilize H2O_(2)and preferentially adsorb Fe^(3+).Herein,we have designed for the first time a flower-like robust SnO_(2)membrane on the ceramic support by in situ template-free one-step hydrothermal method.The three-dimensional loose pore structure in the membrane built by interlacing SnO_(2)nanosheets endows the SnO_(2)membrane with a high specific surface area and abundant adsorption sites(AOH).Based on the coordination complexation and electrostatic attraction between the SnO_(2)surface and Fe^(3+),the membrane shows a high Fe3+removal efficiency(83%)and permeability(24 L·m^(-2)·h^(-1)·MPa^(-1))in H_(2)O_(2).This study provides an innovative and simple approach to designing robust SnO_(2)membranes for highly efficient removal of Fe^(3+)in harsh environments,such as strong oxidation conditions.

Research Progress of Medicinal Secondary Metabolites and Gene Cloning of Dendrobium officinale

Dendrobium officinale is one of the most precious medicinal plants in China. Its main medicinal ingredients are its secondary metabolites. However,it has the characteristics of limited sources,low active ingredient content and high cost,limiting the use of D. officinale.Studying the network structure and rate-limiting steps of secondary metabolites of medicinal components of D. officinale,analyzing the secondary metabolic synthesis process,mastering the production rules of its medicinal components and carrying out gene cloning or biosynthesis,etc.are of great significance for the rational development and utilization of D. officinale resources. This paper briefly reviews the progress of the research on the secondary metabolites of D. officinale,including the detection and identification of metabolites and the identification and cloning of key metabolic enzymes.

Wall-resolved large-eddy simulation of turbulent channel flows with rough walls

Turbulent flows over rough surfaces widely exist in nature and industry.Investigating its mechanism is of theoretical and practical significance.In this work we simulate the turbulent channel flow with rough walls using large-eddy simulation with rough elements resolved using the curvilinear immersed boundary method and compare the results obtained in this work with those in the paper by Yuan and Piomelli(J.Fluid Mech.,vol.760,pp.R1,2014),where the volume of fluid method was employed for modeling rough elements.The mean streamwise velocity profiles predicted by the two methods agree well with each other.Differences in Reynolds stresses and dispersive stresses are observed,which are attributed to the different approaches in dealing with the complex geometry of the rough surface.

Temperature-induced hydrophobicity transition of MXene membrane for directly preparing W/O emulsions

Although hydrophilic membranes are desired for reducing resistance to water permeation, hydrophilic surfaces are not used in the water-in-oil(W/O) membrane emulsification process because water spreads on the hydrophilic surface without forming droplets. Here, we report that a hydrophilic ceramic membrane can form a hydrophobic interface in diesel at a higher temperature;interestingly, the experiments show that the contact angle increases when the temperature rises. The hydrophilic membrane surface evolves into a hydrophobic interface, particularly near the boiling point of water, resulting in a water contact angle of 147.5° ± 1.2°. This work established a method for preparing W/O monodispersed emulsions by direct emulsification of hydrophilic ceramic membranes at a temperature close to the boiling point of water.Additionally, it made high flux of membrane emulsification of monodispersed W/O emulsions possible,which satisfied the industrial requirements of fluidized catalytic cracking in the petrochemical industry.

Effects of biofertilizer and water-saving irrigation interactions on the leaf photosynthesis and plant growth of tomatoes

Irrigation and fertilizer interaction is an efficient cultivation management strategy for facility agriculture.However,the effects of irrigation and fertilizer management on tomato growth and its physiological factors remain unclarified.In this study,two irrigation patterns(W1,conventional irrigation;W2,water-saving irrigation)and four fertilizer application patterns(CF,chemical fertilizer;BOF,biological organic fertilizer;NPK,nutrient compound fertilizer;BOF+NPK)were selected to observe the effects of their interaction on cherry tomato plant growth,leaf photosynthesis and fruit quality through pot experiments.The results showed that W2 treatments promoted plant height growth compared to W1 under the same fertilizer addition.Moreover,irrigation and fertilizer management had significant effects on net photosynthetic rate,intercellular oxidation concentration,stomatal conductance and transpiration rate at the first sequence flowering and fruiting stages.The maximum tomato plant height(99.0 cm)was achieved under the irrigation and fertilizer pattern of BOF and W2,along with the highest fruit yield of 1.98 kg/plant,which was approximately 31.1%higher than the minimum yield under the combined CF and W2 treatment.Under W2 treatments,the application of either NPK or BOF increased the soluble sugar content of tomatoes.The structural equation models showed that the soil alkali hydrolyzed nitrogen could directly significantly affect the yield and soluble sugar.The findings suggest that optimization of irrigation-fertilizer interactions positively regulates tomato growth,providing an efficient model for tomato irrigation and fertilizer management and a reference for sustainable development of facility agriculture.

Effects of urea-N and CO_(2) coupling fertilization on the growth,photosynthesis,yield and anthocyanin content of hydroponic purple cabbage Brassica campestris ssp.chinensis

Water and fertilizer coupling is a high-efficiency technology for the development of facility agriculture.However,the interaction effect of nitrogen(N)and air carbon dioxide(CO_(2))on hydroponic purple cabbage,especially on its leaf anthocyanins under hydroponic solution systems,remains unexplored.In this study,six treatments were set as C0N0,C0N2,C0N4,C1N0,C1N2 and C1N4,with N0,N2 and N4 being 0.0 g/L,0.2 g/L and 0.4 g/L exogenous urea-N to hydroponic solution dilution,respectively.C0 and C1 were set as with and without CO_(2)fertilizer(i.e.,800 g CO_(2)agent added one week after transplanting and 600 g CO_(2)agent added when the plant reached 15 cm in height),respectively.Pot experiments were conducted to investigate the interaction effect of N and air CO_(2)(N×CO_(2))on the growth,photosynthesis,yield and anthocyanin content of hydroponic purple cabbage Brassica campestris ssp.chinensis.The results showed N×CO_(2)extremely significantly influenced plant height(H),net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular oxidation concentration(Ci),transpiration rate(Tr),leaf water use efficiency(LWUE)and yield.The C1N0 treatment had the largest yield at 262.5 g/plant,with higher values for root length,root weight,plant height and leaf number than the other treatments.The Pn,Ci and Tr of C1N4 were the highest at 3.05μmol CO_(2)/m2·s,352.8μmol CO_(2)/m2·s and 2.31 mmol H2O/m2·s,respectively.The C1N2 treatment received the largest Gs value of 0.70 mol H2O/m2·s and the largest Tr of 2.31 mmol H2O/m2·s.There was the highest LWUE for C0N2(1.41)and the highest anthocyanin content for C1N2(1.35 mg/kg).There was a significant negative correlation between leaf number and anthocyanin(r=-0.414,p<0.05).The findings demonstrated that adding CO_(2)fertilizer and 0.2 g/L exogenous urea-N to hydroponic solution dilution is a potential N×CO_(2)coupling strategy to increase anthocyanin and the yield of purple cabbage.

Chirality-dependent concentration boundaries of single-wall carbon nanotubes for photoluminescence characterization and applications

Increasing the concentration of single-wall carbon nanotubes(SWCNTs)is an effective method for enhancing their luminescence intensity.However,an increase in the concentration of SWCNTs would inevitably increase their reabsorption effect,degrading their luminescence efficiency.Herein,we systematically investigated variations in the photoluminescence(PL)intensity of(6,5)single-chirality SWCNTs while increasing their concentration.The results show that the PL intensity first increased to a maximum and then decreased with increasing concentration.Numerical analysis indicates that the concentration boundary corresponding to the maximum PL intensity was strongly dependent on the ratio of the optical absorbances of the SWCNTs at their excitation and emission wavelengths.According to this,statistical analysis by experimentally measuring the optical absorption spectra of 18 kinds of single-chirality SWCNTs shows that the concentration boundaries of SWCNTs were dependent upon their Types and diameters.The concentration boundary of Type I SWCNTs was higher than that of Type II SWCNTs,and the concentration boundaries of both Types increased with increasing diameter.These results provide important guidance for spectral characterization and applications in bioimaging and photoelectronic devices.

Quantitative analysis of the intertube coupling effect on the photoluminescence characteristics of distinct(n,m)carbon nanotubes dispersed in solution

In this work,we quantitatively studied the intertube coupling of different(n,m)-sorted semiconducting single-wall carbon nanotubes(SWCNTs)on their photoluminescence(PL)efficiencies by precisely tuning the ratio of(9,4)and(6,5)SWCNTs in the mixture.A significant decrease in the PL intensity of(9,4)SWCNTs was observed after mixing with(6,5)species when fixing the(9,4)concentration,which was confirmed to be caused by the absorption of incident photons and reabsorption of the emitted photons by the added(6,5)species.By contrast,a similar decrease in the PL intensity of(6,5)SWCNTs was also observed after mixing with the larger-diameter(9,4)species.Different from that of(9,4)SWCNTs,the PL decrease of(6,5)SWCNTs was found to originate not only from photon absorption and reabsorption by the(9,4)species but also from one-way exciton energy transfer(EET)from the(6,5)SWCNTs to the larger-diameter(9,4)SWCNTs.Both the experimental results and numerical simulations further demonstrated that increasing the concentration of mixed(9,4)SWCNTs would enhance the effects of photon absorption and reabsorption and EET on the PL intensity of(6,5)SWCNTs quantified by the decrease ratio of the(6,5)PL intensity.Meanwhile,the influence of EET was found to be always weaker than that of photon absorption and reabsorption.We proposed that the observed EET between isolated SWCNTs in a surfactant solution is derived from their proximity due to Brownian motion.

Large optical nonlinearity enabled by coupled metallic quantum wells

New materials that exhibit strong second-order optical nonlinearities at a desired operational frequency are of paramount importance for nonlinear optics.Giant second-order susceptibility χ^((2)) has been obtained in semiconductor quantum wells(QWs).Unfortunately,the limited confining potential in semiconductor QWs causes formidable challenges in scaling such a scheme to the visible/near-infrared(NIR)frequencies for more vital nonlinear-optic applications.Here,we introduce a metal/dielectric heterostructured platform,i.e.,TiN/Al_(2)O_(3) epitaxial multilayers,to overcome that limitation.This platform has an extremely high χ^((2)) of approximately 1500 pm/V at NIR frequencies.By combining the aforementioned heterostructure with the large electric field enhancement afforded by a nanostructured metasurface,the power efficiency of second harmonic generation(SHG)achieved 10^(−4) at an incident pulse intensity of 10 GW/cm^(2),which is an improvement of several orders of magnitude compared to that of previous demonstrations from nonlinear surfaces at similar frequencies.The proposed quantum-engineered heterostructures enable efficient wave mixing at visible/NIR frequencies into ultracompact nonlinear optical devices.

Dual-mode high-voltage sawtooth wave buncher for low-energy ion injection at HIRFL-SFC cyclotron

Background Sawtooth wave buncher is widely used in low-energy ion injection at cyclotron accelerators.Its performance significantly impacts on the intensity of ion beam delivered to experimental terminals.In order to meet the high-intensity requirement of physical experiments,we upgrade the existing B02 buncher in the axial injection line of the SFC with the dual-model sawtooth wave buncher for low-energy ion injection.Methods We use a three harmonics synthesis method in the dual-sawtooth wave buncher.First,we use three harmonics to generate a low-level sawtooth wave.Second,the low-level wave is amplified by a broadband amplifier to generate high voltage at a single-gap electrode.Third,the electrode is matched to the amplifier by a 1:9 transmission line transformer.Results The new buncher has been installed online since September 2022.Our tested results show that the buncher is capable of being operated at the full-frequency mode and half-frequency mode with the corresponding frequency ranging from 2.75 to 8.0 MHz and 5.5 to 16.0 MHz,respectively.The effective voltage can be up to 2.54 kV and 1.6 kV,respectively.Also,the sawtooth wave buncher works reliably,and a 4.5-8.6 times gain in the beam intensity is achieved.Conclusion By using the three-harmonic synthesis method,a new dual-mode high-voltage sawtooth wave buncher has been built.This sawtooth wave buncher has succeeded in being applied with the high buncher voltage over a wide frequency range with good reliability and stability.This newly-built sawtooth wave buncher significantly increases the ion beam current for low-energy ion injection at the HIRFL-SFC cyclotron.

Interlayer-confined two-dimensional manganese oxide-carbon nanotube catalytic ozonation membrane for efficient water purification

Catalytic ozonation technology has attracted copious attention in water purification owing to its favorable oxidative degradation of pollutants and mitigation of membrane fouling capacity.However,its extensive industrial application has been restricted by the low ozone utilization and limited mass transfer of the short-lived radical species.Interlayer space-confined catalysis has been theoretically proven to be a viable strategy for achieving high catalytic efficiency.Here,a two-dimensional MnO_(2)-incorporated ceramic membrane with tunable interspacing,which was obtained via the intercalation of a carbon nanotube,was designed as a catalytic ozonation membrane reactor for degrading methylene blue.Benefiting from the abundant catalytic active sites on the surface of two-dimensional MnO_(2) as well as the ultralow mass transfer resistance of fluids due to the nanolayer confinement,an excellent mineralization effect,i.e.,1.2 mg O_(3)(aq)mg^(-1) TOC removal(a total organic carbon removal rate of 71.5%),was achieved within a hydraulic retention time of 0.045 s of pollutant degradation.Further,the effects of hydraulic retention time and interlayer spacing on methylene blue removal were investigated.Moreover,the mechanism of the catalytic ozonation employing catalytic ozonation membrane was proposed based on the contribution of the Mn(III/IV)redox pair to electron transfer to generate the reactive oxygen species.This innovative twodimensional confinement catalytic ozonation membrane could act as a nanoreactor and separator to efficiently oxidize organic pollutants and enhance the control of membrane fouling during water purification.

Strain effect on intersubband transitions in rolled-up quantum well infrared photodetectors

Pre-strained nanomembranes with four embedded quantum wells（QWs） are rolled up into threedimensional（3D） tubular QW infrared photodetectors（QWIPs）,which are based on the QW intersubband transition（ISBT）.A redshift of ～0.42 meV in photocurrent response spectra is observed and attributed to two strain contributions due to the rolling of the pre-strained nanomembranes.One is the overall strain that mainly leads to a redshift of ～0.5 meV,and the other is the strain gradient which results in a very tiny variation.The blue shift of the photocurrent response spectra with the external bias are also observed as quantum-confined Stark effect（QCSE）in the ISBT.

Structural characterization of thin-walled microbubble cavities

Whispering gallery mode(WGM)microbubble cavities are a versatile optofluidic sensing platform owing to their hollow core geometry.To increase the light–matter interaction and,thereby,achieve higher sensitivity,thinwalled microbubbles are desirable.However,a lack of knowledge about the precise geometry of hollow microbubbles prevents us from having an accurate theoretical model to describe the WGMs and their response to external stimuli.In this work,we provide a complete characterization of the wall structure of a microbubble and propose a theoretical model for the WGMs in this thin-walled microcavity based on the optical waveguide approach.Structural characterization of the wavelength-scale wall is enabled by focused ion beam milling and scanning electron microscopy imaging.The proposed theoretical model is verified by finite element method simulations.Our approach can readily be extended to other low-dimensional micro-/nanophotonic structures.

Diameter-dependent photoelectric performances of semiconducting carbon nanotubes/perovskite heterojunctions

The heterojunction of single-wall carbon nanotubes(SWCNTs)and perovskite quantum dots(QDs)shows excellent photodetection performances due to the combination of the advantages of high carrier mobility of SWCNTs and high absorption coefficient of perovskite QDs.However,the band structure of a SWCNT is determined by its atomic arrangement structure.How the structure of SWCNTs affects the photoelectric performance of the composite film remains elusive.Here,we systematically explored the diameter effect of SWCNTs with different bandgaps on the photodetection performances of SWCNTs/perovskite QDs heterojunction films by integrating semiconducting SWCNTs(s-SWCNTs)with different diameters with CsPbBr3 QDs.The results show that with an increase in diameter of s-SWCNTs,the heterojunction exhibits increasing responsivity(R),detectivity(D*),and faster response time.The great improvement in the optoelectronic performances of devices should be attributed to the higher carrier mobility of larger-diameter SWCNT films and the increasing built-in electric field at the heterojunction interfaces between larger-diameter SWCNTs and CsPbBr3 QDs,which enhances the separation of the photogenerated excitons and the transport of the resulted carriers in SWCNT films.