This paper demonstrated the generation of multi-wavelength bound state noise-like pulse(BNLP)in a dispersion-managed composite-filtered fiber laser consisting of nonlinear polarization rotation(NPR)and loop.In the cas...This paper demonstrated the generation of multi-wavelength bound state noise-like pulse(BNLP)in a dispersion-managed composite-filtered fiber laser consisting of nonlinear polarization rotation(NPR)and loop.In the case of BNLP,the generation is caused by the interaction between two noise-like pulses(NLPs)induced by the comb-filtering effect,and bound state level can be artificially controlled in the researches.Our work provides a new method for generating low-coherence pulses and establishes a research idea for the study of the comb-filtering effects.展开更多
Recent theoretical verification of self-similar and dissipative pure-quartic solitons(PQSs)emphasized the similarity between PQS lasers and conventional fiber lasers,but the unique equilibrium mechanism hinders the fo...Recent theoretical verification of self-similar and dissipative pure-quartic solitons(PQSs)emphasized the similarity between PQS lasers and conventional fiber lasers,but the unique equilibrium mechanism hinders the formation of PQS molecules in normal fourth-order dispersion(FOD)regimes.In this paper,we investigated the effect of filters on shaping PQSs in normal FOD based on a passively mode-locked fiber laser model.A bandpass filter eliminates the time pedestal of dissipative PQSs,thus realizing a multi-pulsing state.When the filter bandwidth is appropriate,the effective spectral filtering effect can lower the pulse splitting threshold and enable the coherent restoration from chaotic PQSs to PQS molecules.Additionally,changing the central wavelength of the filter can generate PQSs and PQS molecules with asymmetric intensity distributions.These results are important guides for the manipulation of PQSs and the construction of high repetition-frequency fiber lasers.展开更多
The spin caloritronic properties of the Janus VSTe monolayer were investigated using density functional theory(DFT)and the non-equilibrium Green’s function(NEGF)method,implemented in the Atomistix Toolkit(ATK)package...The spin caloritronic properties of the Janus VSTe monolayer were investigated using density functional theory(DFT)and the non-equilibrium Green’s function(NEGF)method,implemented in the Atomistix Toolkit(ATK)package.Our study revealed significant spin-splitting within the Janus VSTe monolayer,which induced spin currents under a temperature gradient across the device.By applying a 1%tensile strain,the Janus VSTe monolayer exhibited a perfect thermal spin filtering effect(SFE),with the spin-up current nearly suppressed to zero.Both the unstrained and strained Janus VSTe monolayers demonstrated excellent spin caloritronic properties,with spin figures of merit of 10.915 and 8.432 at an average temperature of 100 K,respectively.Notably,these properties were found to be sensitive to temperature,performing optimally at lower temperatures.These results suggest a promising avenue for designing spin caloritronic devices aimed at efficient waste heat recovery.展开更多
Moleculardeviceswith highswitchingperformance and/or the perfect spin filtering effect have always been the pursuit with the development of molecular electronics.Hereb,yusingthe 2001.0V nonequilibrium.Green's func...Moleculardeviceswith highswitchingperformance and/or the perfect spin filtering effect have always been the pursuit with the development of molecular electronics.Hereb,yusingthe 2001.0V nonequilibrium.Green's function method in combination with the density functionaltheory,the switching performance and spin filtering properties of dimethyldihydropyrene(DHP)/cyclophanediene(CPD)photoswitchable molecule connected by carbon atomic chains(CACs)to two zigzag graphene nanoribbon electrodes have been theoretically investigated.The results show that DHP is more conductive than CPD and therefore an evident switching effect is demonstrated,and the switching ratio(RON/OFF)can reach 4.5×103.It is further revealed that the RoON/OF of DHP/CPD closely depends on the length of CACs.More specifically,the RoN/OFF values of DHP/CPD with odd-numbered CACs are larger than those with even-numbered CACs.More interestingly,a high or even perfect spin filtering effect can be obtained in these investigated DHP/CPD single-molecule devices.Our study is helpful for future design of single-molecule switches and spin filters and provides a way to optimize their performance by means of varying the length of bridging CACs.展开更多
Chromium is a harmful contaminant showing mutagenicity and carcinogenicity.Therefore,detection of chromium requires the development of low-cost and high-sensitivity sensors.Herein,blue-fluorescent carbon quantum dots ...Chromium is a harmful contaminant showing mutagenicity and carcinogenicity.Therefore,detection of chromium requires the development of low-cost and high-sensitivity sensors.Herein,blue-fluorescent carbon quantum dots were synthesized by one-step hydrothermal method from alkali-soluble Poria cocos polysaccharide,which is green source,cheap and easy to obtain,and has no pharmacological activity due to low water solubility.These carbon quantum dots exhibit good fluorescence stability,water solubility,anti-interference and low cytotoxicity,and can be specifically combined with the detection of Cr(Ⅵ)to form a non-fluorescent complex that causes fluorescence quenching,so they can be used as a label-free nanosensor.High-sensitivity detection of Cr(Ⅵ)was achieved through internal filtering and static quenching effects.The fluorescence quenching degree of carbon dots fluorescent probe showed a good linear relationship with Cr(Ⅵ)concentration in the range of 1-100μM.The linear equation was F;/F=0.9942+0.01472[Cr(Ⅵ)](R;=0.9922),and the detection limit can be as low as 0.25μM(S/N=3),which has been successfully applied to Cr(Ⅵ)detection in actual water samples herein.展开更多
Cadmium ion(Cd^(2+))detection technology plays a prominent role in food safety and human health.Herein,we designed and constructed an 2-aminoethyl dihydrogen phosphate(AEP)@upconversion nanoparticles(UCNPs)fluorescenc...Cadmium ion(Cd^(2+))detection technology plays a prominent role in food safety and human health.Herein,we designed and constructed an 2-aminoethyl dihydrogen phosphate(AEP)@upconversion nanoparticles(UCNPs)fluorescence sensor for quantitative detection of Cd^(2+)in paddy rice based on inner filter effect(IFE)combined with enzyme inhibition mechanism.The AEP modification UCNPs can offer a stable fluorescence donor at 658 nm and be quenched by the oxidized tetramethylbenzidine(oxTMB)catalyzed by horseradish peroxidase(HRP)enzymes.Without addition of Cd^(2+),the fluorescence of AEP@UCNPs fluorescence sensor was weaken due to the IFE between AEP@UCNPs and oxTMB.With addition of Cd^(2+),HRP enzyme activity was inhibited by Cd^(2+),leading to the decreased oxTMB,resulting in the enhance upconversion fluorescence intensity.As a result,the fluorescence intensity signal at 658 nm of the IFE-based AEP@UCNPs fluorescence sensor increased linearly with the increase in Cd^(2+)in a wide range from 0.5μmol/L to 6μmol/L and the limit of detection(LOD)was 24.6 n mol/L.In addition,our proposed IFE-based AEP@UCNPs fluorescence sensor can achieve Cd^(2+)detection in paddy rice in 30 min.展开更多
In low-light image enhancement,prevailing Retinex-based methods often struggle with precise illumina-tion estimation and brightness modulation.This can result in issues such as halo artifacts,blurred edges,and diminis...In low-light image enhancement,prevailing Retinex-based methods often struggle with precise illumina-tion estimation and brightness modulation.This can result in issues such as halo artifacts,blurred edges,and diminished details in bright regions,particularly under non-uniform illumination conditions.We propose an innovative approach that refines low-light images by leveraging an in-depth awareness of local content within the image.By introducing multi-scale effective guided filtering,our method surpasses the limitations of traditional isotropic filters,such as Gaussian filters,in handling non-uniform illumination.It dynamically adjusts regularization parameters in response to local image characteristics and significantly integrates edge perception across different scales.This balanced approach achieves a harmonious blend of smoothing and detail preservation,enabling more accurate illumination estimation.Additionally,we have designed an adaptive gamma correction function that dynamically adjusts the brightness value based on local pixel intensity,further balancing enhancement effects across different brightness levels in the image.Experimental results demonstrate the effectiveness of our proposed method for non-uniform illumination images across various scenarios.It exhibits superior quality and objective evaluation scores compared to existing methods.Our method effectively addresses potential issues that existing methods encounter when processing non-uniform illumination images,producing enhanced images with precise details and natural,vivid colors.展开更多
Variation of plastic viscosity and extrapolated shear yield stress with the concentration of Dispex A40 for the concentrated Alcoa A16 alpha -Al2O3 suspensions at 0.27 powder volume fraction was investigated at 294 K....Variation of plastic viscosity and extrapolated shear yield stress with the concentration of Dispex A40 for the concentrated Alcoa A16 alpha -Al2O3 suspensions at 0.27 powder volume fraction was investigated at 294 K. An optimum level of Dispex A40 for full deflocculation is found to be at 0.18% mass fraction of the powder, at which the rheological behaviour shows little different to that of adjusting the pH to 4 to obtain full deflocculation. It is demonstrated that the shear stress drop can roughly work as an index for the thixotropy in particular fixed conditions, and consequently an index for the deflocculation as the shear stress drop becomes larger when the level of the flocculation increases, and vice versa. It is also found that the addition of Dispex A40 can prevent the filter cakes from cracking, whereas the cakes at various pH values with polyvinyl alcohol as a sole polymer normally develop cracking during drying.展开更多
The realization of a perfect spin or valley filtering effect in two-dimensional graphene-like materials is one of the fundamental objectives in spintronics and valleytronics. For this purpose, we study spin- and valle...The realization of a perfect spin or valley filtering effect in two-dimensional graphene-like materials is one of the fundamental objectives in spintronics and valleytronics. For this purpose, we study spin- and valley-dependent transport in a silicene system with spatially alternative strains. It is found that due to the valley-opposite gauge field induced by the strain, the strained silicene with a superlattice structure exhibits an angle-resolved valley and spin filtering effect when the spin–orbit interaction is considered. When the interaction that breaks the time reversal symmetry is introduced, such as the spin or valley dependent staggered magnetization, the system is shown to be a perfect spin and valley half metal in which only one spin and valley species is allowed to transport. Our findings are helpful to design both spintronic and valleytronic devices based on silicene.展开更多
Interface engineering has been regarded as an effective strategy to manipulate the thermoelectric performance of materials.Here,we use a facile chemical electroless plating and a spark plasma sintering process to fabr...Interface engineering has been regarded as an effective strategy to manipulate the thermoelectric performance of materials.Here,we use a facile chemical electroless plating and a spark plasma sintering process to fabricate Ag-plated SnTe bulk.After sintering,a small amount of plated Ag can be doped into SnTe to suppress the Sn vacancies and the others form Ag precipitates with a size distribution from nanoscale to microscale,which introduces Ag/SnTe interfaces to enhance the Seebeck coefficient via energy filtering effect.Simultaneously,these structures result in strong scattering to reach a low lattice thermal conductivity of-0.62 W·m^(–1)·K^(–1).Consequently,a maximum figure of merit(zT)of-0.67 at 823 K is achieved in 2 wt%Ag-plated SnTe,which is-60%higher than that of pristine SnTe.Moreover,the microhardness indentation test results show that the mean microhardness of 2 wt%Ag-plated SnTe is HV 64.26,which is much higher than that of pristine SnTe,indicating that Ag electroless plating can improve the mechanical properties of SnTe.This work has provided a facile and eco-friendly method to realize the interface engineering for manipulating the thermoelectric and mechanical properties of SnTe.展开更多
Circular thin-plate electrostatic sensors are promising in gas path monitoring due to their advantages of non-intrusiveness and easy installation. The spatial sensitivity and filtering effect are two important perform...Circular thin-plate electrostatic sensors are promising in gas path monitoring due to their advantages of non-intrusiveness and easy installation. The spatial sensitivity and filtering effect are two important performance parameters. In this paper, an analytically mathematical model of induced charge on a circular thin-plate electrode is first derived. Then the spatial sensitivity and filtering effect of the circular electrostatic sensor are investigated by numerical calculations. Finally,experimental studies are performed to testify the theoretical results. Both theoretical and experimental results demonstrate that circular thin-plate electrostatic sensors act as a low-pass filter in the spatial frequency domain, and both the spatial filtering effect and the temporal frequency response characteristics depend strongly on the spatial position and velocity of the charged particle. These conclusions can provide guidelines for the optimal design of circular thin-plate electrostatic sensors.展开更多
Exploring silicon-based spin modulating junction is one of the most promising areas of spintronics.Using nonequilibrium Green's function combined with density functional theory,a set of spin filters of hydrogenate...Exploring silicon-based spin modulating junction is one of the most promising areas of spintronics.Using nonequilibrium Green's function combined with density functional theory,a set of spin filters of hydrogenated zigzag silicene nanoribbons is designed by substituting a silicon atom with a boron one and the spin-correlated transport properties are studied.The results show that the spin polarization can be realized by structural symmetry breaking induced by boron doping.Remarkably,by tuning the edge hydrogenation,it is found that the spin filter efficiency can be varied from 30%to 58%.Moreover,it is also found and explained that the asymmetric hydrogenation can give rise to an obvious negative differential resistance which usually appears at weakly coupled junction.These findings indicate that the boron-doped ZSiNR is a promising material for spintronic applications.展开更多
Oxidizing CIO^(-)and IO_(4)^(-)exist widely in environment and are closely related to the health of organisms.Accordingly,fast,sensitive,and direct detection of the two species is significant.Using IFE in UCNPs@PAA an...Oxidizing CIO^(-)and IO_(4)^(-)exist widely in environment and are closely related to the health of organisms.Accordingly,fast,sensitive,and direct detection of the two species is significant.Using IFE in UCNPs@PAA and Fe(Ⅱ)-phenanthroline system,an elegant ratiometric fluorescent nanosensor,without noble metal nanoparticle,was designed for the detection of CIO-and IO4-.Fe(Ⅱ)-phenanthroline complex is used as fluorescent absorber,which can quench green light of UCNPs with gradually varied extent depending on the concentration of Fe(Ⅱ).The linear zone extends to 800 and 120μmol/L while the detection limit is 1.30 and 0.58μmol/L for NaCIO and NaIO_(4),respectively.Finally,the nanosensor was successfully applied to detect NaCIO and NaIO4spiked in milk,spring water,and tap water with good recoveries.展开更多
A new facile fluorescence probing strategy, which was based on N-doped carbon dots（NCDs） and methyl parathion hydrolase（MPH）, was developed for the determination of parathion-methyl（PM）. The fluorescence intensi...A new facile fluorescence probing strategy, which was based on N-doped carbon dots（NCDs） and methyl parathion hydrolase（MPH）, was developed for the determination of parathion-methyl（PM）. The fluorescence intensity of NCDs-MPH system was proportional to PM concentration in the range of 2.38–73.78 mmol/L, with a detection limit of 0.338 mmol/L. Moreover, the present simple and facile method could be used to determine methyl parathion in environmental and agricultural samples successfully.Furthermore, the detection mechanism of this system is inner filter effect and molecular interactions between NCDs and p-nitrophenol, which is the hydrolysis product of PM catalyzed by methyl parathion hydrolase.展开更多
In this paper,a Doppler scaling fast Fourier transform（Doppler-FFT）algorithm for filter bank multi-carrier（FBMC）is proposed,which can efficiently eliminate the impact of the Doppler scaling in satellite communicat...In this paper,a Doppler scaling fast Fourier transform（Doppler-FFT）algorithm for filter bank multi-carrier（FBMC）is proposed,which can efficiently eliminate the impact of the Doppler scaling in satellite communications.By introducing a Doppler scaling factor into the butterfly structure of the fast Fourier transform（FFT）algorithm,the proposed algorithm eliminates the differences between the Doppler shifts of the received subcarriers,and maintains the same order of computational complexity compared to that of the traditional FFT.In the process of using the new method,the Doppler scaling should be estimated by calculating the orbital data in advance.Thus,the inter-symbol interference（ISI）and the inter-carrier interference（ICI）can be completely eliminated,and the signal to interference and noise ratio（SINR）will not be affected.Simulation results also show that the proposed algorithm can achieve a 0.4 d B performance gain compared to the frequency domain equalization（FDE）algorithm in satellite communications.展开更多
We theoretically investigate the wave-vector filtering(WVF)effect for electrons in an antiparallel asymmetric doubleδ-magnetic-barrier microstructure under a bias,which can be fabricated experimentally by patterning ...We theoretically investigate the wave-vector filtering(WVF)effect for electrons in an antiparallel asymmetric doubleδ-magnetic-barrier microstructure under a bias,which can be fabricated experimentally by patterning two asymmetric ferromagnetic(FM)stripes on the top and the bottom of GaAs/AlxGa1−xAs heterostructure,respectively.It is found that an appreciable WVF effect appears because of an essentially two-dimensional(2D)process for electrons across this microstructure.WVF effect is found to be sensitive to the applied bias.WVF efficiency can be tuned by changing bias,which may lead to an electrically-controllable momentum filter for nanoelectronics device applications.展开更多
An improved preprocessed Yaroslavsky filter（IPYF）is proposed to avoid the nick effects and obtain a better denoising result when the noise variance is unknown.Different from its predecessors,the similarity between t...An improved preprocessed Yaroslavsky filter（IPYF）is proposed to avoid the nick effects and obtain a better denoising result when the noise variance is unknown.Different from its predecessors,the similarity between two pixels is calculated by shearlet features.The feature vector consists of initial denoised results by the non-subsampled shearlet transform hard thresholding（NSST-HT）and NSST coefficients,which can help allocate the averaging weights more reasonably.With the correct estimated noise variance,the NSST-HT can provide good denoised results as the initial estimation and high-frequency coefficients contribute large weights to preserve textures.In case of the incorrect estimated noise variance,the low-frequency coefficients will mitigate the nick effect in cartoon regions greatly,making the IPYF more robust than the original PYF.Detailed experimental results show that the IPYF is a very competitive method based on a comprehensive consideration involving peak signal to noise ratio（PSNR）,computing time,visual quality and method noise.展开更多
The previous works commonly adjust the carrier concentration through acceptor doping,but at the same time,the decrease of the Seebeck coefficient limits the further improvement of electrical properties in Cu_(3)SbSe_(...The previous works commonly adjust the carrier concentration through acceptor doping,but at the same time,the decrease of the Seebeck coefficient limits the further improvement of electrical properties in Cu_(3)SbSe_(4)-based materials.In this work,a microwave-assisted hydrothermal synthesis method was used to synthesize Cu_(3)SbSe_(4)/TiO_(2) hollow microspheres.Part of TiO_(2) participates in the reaction,replaces the Sb site of Cu_(3)SbSe_(4) to form holes,and the rest is dispersed in the matrix in the form of the second phase.The first-principles calculations reveal that the doping of Ti significantly changes the band structure and phonon spectrum,thereby regulating carrier concentration while increasing phonon scattering.In addition,experimental results show that the energy filtering effect generated by the extra-mixed TiO_(2) nano particles,which suppresses the decrease of Seebeck coefficient by acceptor doping.Consequently,the highest average power factor 897.5 mW m^(-1) K^(-2) and the zT peak value of 0.70 can be obtained in Cu_(3)SbSe_(4)/6%TiO_(2) sample at 298e623 K.This work provides a new sight to improve the thermoelectric properties in Cu_(3)SbSe_(4) through carrier concentration regulation and nano-phase composition.展开更多
A wide range (9.4nm) tuning of vertically coupled microring resonator filter was demonstrated utilizing a large TO coefficient of polymer. The power consumption was about 60m W and no degradation of filter response wa...A wide range (9.4nm) tuning of vertically coupled microring resonator filter was demonstrated utilizing a large TO coefficient of polymer. The power consumption was about 60m W and no degradation of filter response was observed.展开更多
基金supported by the Research Fund of Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology(No.2020B1212030010)。
文摘This paper demonstrated the generation of multi-wavelength bound state noise-like pulse(BNLP)in a dispersion-managed composite-filtered fiber laser consisting of nonlinear polarization rotation(NPR)and loop.In the case of BNLP,the generation is caused by the interaction between two noise-like pulses(NLPs)induced by the comb-filtering effect,and bound state level can be artificially controlled in the researches.Our work provides a new method for generating low-coherence pulses and establishes a research idea for the study of the comb-filtering effects.
基金Project supported by the National Natural Science Foundation of China(Grant No.62175116)。
文摘Recent theoretical verification of self-similar and dissipative pure-quartic solitons(PQSs)emphasized the similarity between PQS lasers and conventional fiber lasers,but the unique equilibrium mechanism hinders the formation of PQS molecules in normal fourth-order dispersion(FOD)regimes.In this paper,we investigated the effect of filters on shaping PQSs in normal FOD based on a passively mode-locked fiber laser model.A bandpass filter eliminates the time pedestal of dissipative PQSs,thus realizing a multi-pulsing state.When the filter bandwidth is appropriate,the effective spectral filtering effect can lower the pulse splitting threshold and enable the coherent restoration from chaotic PQSs to PQS molecules.Additionally,changing the central wavelength of the filter can generate PQSs and PQS molecules with asymmetric intensity distributions.These results are important guides for the manipulation of PQSs and the construction of high repetition-frequency fiber lasers.
基金Project(2022JJ30049)supported by the Natural Science Foundation of Hunan Province,China。
文摘The spin caloritronic properties of the Janus VSTe monolayer were investigated using density functional theory(DFT)and the non-equilibrium Green’s function(NEGF)method,implemented in the Atomistix Toolkit(ATK)package.Our study revealed significant spin-splitting within the Janus VSTe monolayer,which induced spin currents under a temperature gradient across the device.By applying a 1%tensile strain,the Janus VSTe monolayer exhibited a perfect thermal spin filtering effect(SFE),with the spin-up current nearly suppressed to zero.Both the unstrained and strained Janus VSTe monolayers demonstrated excellent spin caloritronic properties,with spin figures of merit of 10.915 and 8.432 at an average temperature of 100 K,respectively.Notably,these properties were found to be sensitive to temperature,performing optimally at lower temperatures.These results suggest a promising avenue for designing spin caloritronic devices aimed at efficient waste heat recovery.
基金This work is supported by the National Natural Sci-ence Foundation China(No.22173052 of and No.11974217).
文摘Moleculardeviceswith highswitchingperformance and/or the perfect spin filtering effect have always been the pursuit with the development of molecular electronics.Hereb,yusingthe 2001.0V nonequilibrium.Green's function method in combination with the density functionaltheory,the switching performance and spin filtering properties of dimethyldihydropyrene(DHP)/cyclophanediene(CPD)photoswitchable molecule connected by carbon atomic chains(CACs)to two zigzag graphene nanoribbon electrodes have been theoretically investigated.The results show that DHP is more conductive than CPD and therefore an evident switching effect is demonstrated,and the switching ratio(RON/OFF)can reach 4.5×103.It is further revealed that the RoON/OF of DHP/CPD closely depends on the length of CACs.More specifically,the RoN/OFF values of DHP/CPD with odd-numbered CACs are larger than those with even-numbered CACs.More interestingly,a high or even perfect spin filtering effect can be obtained in these investigated DHP/CPD single-molecule devices.Our study is helpful for future design of single-molecule switches and spin filters and provides a way to optimize their performance by means of varying the length of bridging CACs.
基金financially supported by the Natural Science Foundation of Anhui University of Chinese Medicine (Grant No.: 2018zrzd04)Anhui Provincial Natural Science Foundation (Grant No.: 1908085QH351)+2 种基金Major Science and Technology Projects of Anhui Province (Grant No.: 18030801131)National Key Research and Development Project (Grant No.: 2017YFC1701600)Anhui Province’s Central Special Fund for Local Science and Technology Development (Grant No.: 201907d07050002)
文摘Chromium is a harmful contaminant showing mutagenicity and carcinogenicity.Therefore,detection of chromium requires the development of low-cost and high-sensitivity sensors.Herein,blue-fluorescent carbon quantum dots were synthesized by one-step hydrothermal method from alkali-soluble Poria cocos polysaccharide,which is green source,cheap and easy to obtain,and has no pharmacological activity due to low water solubility.These carbon quantum dots exhibit good fluorescence stability,water solubility,anti-interference and low cytotoxicity,and can be specifically combined with the detection of Cr(Ⅵ)to form a non-fluorescent complex that causes fluorescence quenching,so they can be used as a label-free nanosensor.High-sensitivity detection of Cr(Ⅵ)was achieved through internal filtering and static quenching effects.The fluorescence quenching degree of carbon dots fluorescent probe showed a good linear relationship with Cr(Ⅵ)concentration in the range of 1-100μM.The linear equation was F;/F=0.9942+0.01472[Cr(Ⅵ)](R;=0.9922),and the detection limit can be as low as 0.25μM(S/N=3),which has been successfully applied to Cr(Ⅵ)detection in actual water samples herein.
基金financially supported by the National Natural Science Foundation of China(32202132,32172229)Young Elite Scientists Sponsorship Program by CAST(2022QNRC001)the Priority Academic Program Development of Jiangsu Higher Educations(PAPD)。
文摘Cadmium ion(Cd^(2+))detection technology plays a prominent role in food safety and human health.Herein,we designed and constructed an 2-aminoethyl dihydrogen phosphate(AEP)@upconversion nanoparticles(UCNPs)fluorescence sensor for quantitative detection of Cd^(2+)in paddy rice based on inner filter effect(IFE)combined with enzyme inhibition mechanism.The AEP modification UCNPs can offer a stable fluorescence donor at 658 nm and be quenched by the oxidized tetramethylbenzidine(oxTMB)catalyzed by horseradish peroxidase(HRP)enzymes.Without addition of Cd^(2+),the fluorescence of AEP@UCNPs fluorescence sensor was weaken due to the IFE between AEP@UCNPs and oxTMB.With addition of Cd^(2+),HRP enzyme activity was inhibited by Cd^(2+),leading to the decreased oxTMB,resulting in the enhance upconversion fluorescence intensity.As a result,the fluorescence intensity signal at 658 nm of the IFE-based AEP@UCNPs fluorescence sensor increased linearly with the increase in Cd^(2+)in a wide range from 0.5μmol/L to 6μmol/L and the limit of detection(LOD)was 24.6 n mol/L.In addition,our proposed IFE-based AEP@UCNPs fluorescence sensor can achieve Cd^(2+)detection in paddy rice in 30 min.
文摘In low-light image enhancement,prevailing Retinex-based methods often struggle with precise illumina-tion estimation and brightness modulation.This can result in issues such as halo artifacts,blurred edges,and diminished details in bright regions,particularly under non-uniform illumination conditions.We propose an innovative approach that refines low-light images by leveraging an in-depth awareness of local content within the image.By introducing multi-scale effective guided filtering,our method surpasses the limitations of traditional isotropic filters,such as Gaussian filters,in handling non-uniform illumination.It dynamically adjusts regularization parameters in response to local image characteristics and significantly integrates edge perception across different scales.This balanced approach achieves a harmonious blend of smoothing and detail preservation,enabling more accurate illumination estimation.Additionally,we have designed an adaptive gamma correction function that dynamically adjusts the brightness value based on local pixel intensity,further balancing enhancement effects across different brightness levels in the image.Experimental results demonstrate the effectiveness of our proposed method for non-uniform illumination images across various scenarios.It exhibits superior quality and objective evaluation scores compared to existing methods.Our method effectively addresses potential issues that existing methods encounter when processing non-uniform illumination images,producing enhanced images with precise details and natural,vivid colors.
文摘Variation of plastic viscosity and extrapolated shear yield stress with the concentration of Dispex A40 for the concentrated Alcoa A16 alpha -Al2O3 suspensions at 0.27 powder volume fraction was investigated at 294 K. An optimum level of Dispex A40 for full deflocculation is found to be at 0.18% mass fraction of the powder, at which the rheological behaviour shows little different to that of adjusting the pH to 4 to obtain full deflocculation. It is demonstrated that the shear stress drop can roughly work as an index for the thixotropy in particular fixed conditions, and consequently an index for the deflocculation as the shear stress drop becomes larger when the level of the flocculation increases, and vice versa. It is also found that the addition of Dispex A40 can prevent the filter cakes from cracking, whereas the cakes at various pH values with polyvinyl alcohol as a sole polymer normally develop cracking during drying.
文摘The realization of a perfect spin or valley filtering effect in two-dimensional graphene-like materials is one of the fundamental objectives in spintronics and valleytronics. For this purpose, we study spin- and valley-dependent transport in a silicene system with spatially alternative strains. It is found that due to the valley-opposite gauge field induced by the strain, the strained silicene with a superlattice structure exhibits an angle-resolved valley and spin filtering effect when the spin–orbit interaction is considered. When the interaction that breaks the time reversal symmetry is introduced, such as the spin or valley dependent staggered magnetization, the system is shown to be a perfect spin and valley half metal in which only one spin and valley species is allowed to transport. Our findings are helpful to design both spintronic and valleytronic devices based on silicene.
基金This work was financially supported by the National Natural Science Foundation of China(No.51802205)Australian Research Council.
文摘Interface engineering has been regarded as an effective strategy to manipulate the thermoelectric performance of materials.Here,we use a facile chemical electroless plating and a spark plasma sintering process to fabricate Ag-plated SnTe bulk.After sintering,a small amount of plated Ag can be doped into SnTe to suppress the Sn vacancies and the others form Ag precipitates with a size distribution from nanoscale to microscale,which introduces Ag/SnTe interfaces to enhance the Seebeck coefficient via energy filtering effect.Simultaneously,these structures result in strong scattering to reach a low lattice thermal conductivity of-0.62 W·m^(–1)·K^(–1).Consequently,a maximum figure of merit(zT)of-0.67 at 823 K is achieved in 2 wt%Ag-plated SnTe,which is-60%higher than that of pristine SnTe.Moreover,the microhardness indentation test results show that the mean microhardness of 2 wt%Ag-plated SnTe is HV 64.26,which is much higher than that of pristine SnTe,indicating that Ag electroless plating can improve the mechanical properties of SnTe.This work has provided a facile and eco-friendly method to realize the interface engineering for manipulating the thermoelectric and mechanical properties of SnTe.
基金supported by the National Natural Science Foundation of China(Nos.51275520,50805142)
文摘Circular thin-plate electrostatic sensors are promising in gas path monitoring due to their advantages of non-intrusiveness and easy installation. The spatial sensitivity and filtering effect are two important performance parameters. In this paper, an analytically mathematical model of induced charge on a circular thin-plate electrode is first derived. Then the spatial sensitivity and filtering effect of the circular electrostatic sensor are investigated by numerical calculations. Finally,experimental studies are performed to testify the theoretical results. Both theoretical and experimental results demonstrate that circular thin-plate electrostatic sensors act as a low-pass filter in the spatial frequency domain, and both the spatial filtering effect and the temporal frequency response characteristics depend strongly on the spatial position and velocity of the charged particle. These conclusions can provide guidelines for the optimal design of circular thin-plate electrostatic sensors.
基金the National Natural Science Foundations of China(Grant No.11574118)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2019PEM006).
文摘Exploring silicon-based spin modulating junction is one of the most promising areas of spintronics.Using nonequilibrium Green's function combined with density functional theory,a set of spin filters of hydrogenated zigzag silicene nanoribbons is designed by substituting a silicon atom with a boron one and the spin-correlated transport properties are studied.The results show that the spin polarization can be realized by structural symmetry breaking induced by boron doping.Remarkably,by tuning the edge hydrogenation,it is found that the spin filter efficiency can be varied from 30%to 58%.Moreover,it is also found and explained that the asymmetric hydrogenation can give rise to an obvious negative differential resistance which usually appears at weakly coupled junction.These findings indicate that the boron-doped ZSiNR is a promising material for spintronic applications.
基金Project supported by the Natural Science Foundation of Shandong Province(ZR2016EMM20,ZR2019PEM012)National Natural Science Foundation of China(21808114)the Foundation(ZZ20190310)of State Key Laboratory of Biobased Material and Green Papermaking。
文摘Oxidizing CIO^(-)and IO_(4)^(-)exist widely in environment and are closely related to the health of organisms.Accordingly,fast,sensitive,and direct detection of the two species is significant.Using IFE in UCNPs@PAA and Fe(Ⅱ)-phenanthroline system,an elegant ratiometric fluorescent nanosensor,without noble metal nanoparticle,was designed for the detection of CIO-and IO4-.Fe(Ⅱ)-phenanthroline complex is used as fluorescent absorber,which can quench green light of UCNPs with gradually varied extent depending on the concentration of Fe(Ⅱ).The linear zone extends to 800 and 120μmol/L while the detection limit is 1.30 and 0.58μmol/L for NaCIO and NaIO_(4),respectively.Finally,the nanosensor was successfully applied to detect NaCIO and NaIO4spiked in milk,spring water,and tap water with good recoveries.
基金supported by the National Natural Science Foundation of China(No.21207057)the Fundamental Research Funds for the Central Universities(No.lzujbky-201643)
文摘A new facile fluorescence probing strategy, which was based on N-doped carbon dots（NCDs） and methyl parathion hydrolase（MPH）, was developed for the determination of parathion-methyl（PM）. The fluorescence intensity of NCDs-MPH system was proportional to PM concentration in the range of 2.38–73.78 mmol/L, with a detection limit of 0.338 mmol/L. Moreover, the present simple and facile method could be used to determine methyl parathion in environmental and agricultural samples successfully.Furthermore, the detection mechanism of this system is inner filter effect and molecular interactions between NCDs and p-nitrophenol, which is the hydrolysis product of PM catalyzed by methyl parathion hydrolase.
基金supported by the National Natural Science Foundation of China (No. 91438116)by the Program for New Century Excellent Talents in University of China (No. NCET-12-0030)+1 种基金by the National Hi-Tech R&D Program of China (No. 2015AA7014065)by the Shanghai Aerospace Science and Technology Innovation Fund (No. SAST2015089)
文摘In this paper,a Doppler scaling fast Fourier transform（Doppler-FFT）algorithm for filter bank multi-carrier（FBMC）is proposed,which can efficiently eliminate the impact of the Doppler scaling in satellite communications.By introducing a Doppler scaling factor into the butterfly structure of the fast Fourier transform（FFT）algorithm,the proposed algorithm eliminates the differences between the Doppler shifts of the received subcarriers,and maintains the same order of computational complexity compared to that of the traditional FFT.In the process of using the new method,the Doppler scaling should be estimated by calculating the orbital data in advance.Thus,the inter-symbol interference（ISI）and the inter-carrier interference（ICI）can be completely eliminated,and the signal to interference and noise ratio（SINR）will not be affected.Simulation results also show that the proposed algorithm can achieve a 0.4 d B performance gain compared to the frequency domain equalization（FDE）algorithm in satellite communications.
基金supported by the National Natural Science Foundation of China(Grant No.11864009).
文摘We theoretically investigate the wave-vector filtering(WVF)effect for electrons in an antiparallel asymmetric doubleδ-magnetic-barrier microstructure under a bias,which can be fabricated experimentally by patterning two asymmetric ferromagnetic(FM)stripes on the top and the bottom of GaAs/AlxGa1−xAs heterostructure,respectively.It is found that an appreciable WVF effect appears because of an essentially two-dimensional(2D)process for electrons across this microstructure.WVF effect is found to be sensitive to the applied bias.WVF efficiency can be tuned by changing bias,which may lead to an electrically-controllable momentum filter for nanoelectronics device applications.
基金Supported by Open Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University)(PL N1303)Open Fund of State Key Laboratory of Marine Geology(Tongji University)(MGK1412)+1 种基金Fundation of Graduate Innovation Center in NUAA(kfjj201430)the Fundamental Research Funds for the Central Universities
文摘An improved preprocessed Yaroslavsky filter（IPYF）is proposed to avoid the nick effects and obtain a better denoising result when the noise variance is unknown.Different from its predecessors,the similarity between two pixels is calculated by shearlet features.The feature vector consists of initial denoised results by the non-subsampled shearlet transform hard thresholding（NSST-HT）and NSST coefficients,which can help allocate the averaging weights more reasonably.With the correct estimated noise variance,the NSST-HT can provide good denoised results as the initial estimation and high-frequency coefficients contribute large weights to preserve textures.In case of the incorrect estimated noise variance,the low-frequency coefficients will mitigate the nick effect in cartoon regions greatly,making the IPYF more robust than the original PYF.Detailed experimental results show that the IPYF is a very competitive method based on a comprehensive consideration involving peak signal to noise ratio（PSNR）,computing time,visual quality and method noise.
基金This work was financially supported by the National Natural Science Foundation of China(No.51871240).The calculations were carried out at the National Supercomputing Center in Shenzhen(Shenzhen Cloud Computing Center).
文摘The previous works commonly adjust the carrier concentration through acceptor doping,but at the same time,the decrease of the Seebeck coefficient limits the further improvement of electrical properties in Cu_(3)SbSe_(4)-based materials.In this work,a microwave-assisted hydrothermal synthesis method was used to synthesize Cu_(3)SbSe_(4)/TiO_(2) hollow microspheres.Part of TiO_(2) participates in the reaction,replaces the Sb site of Cu_(3)SbSe_(4) to form holes,and the rest is dispersed in the matrix in the form of the second phase.The first-principles calculations reveal that the doping of Ti significantly changes the band structure and phonon spectrum,thereby regulating carrier concentration while increasing phonon scattering.In addition,experimental results show that the energy filtering effect generated by the extra-mixed TiO_(2) nano particles,which suppresses the decrease of Seebeck coefficient by acceptor doping.Consequently,the highest average power factor 897.5 mW m^(-1) K^(-2) and the zT peak value of 0.70 can be obtained in Cu_(3)SbSe_(4)/6%TiO_(2) sample at 298e623 K.This work provides a new sight to improve the thermoelectric properties in Cu_(3)SbSe_(4) through carrier concentration regulation and nano-phase composition.
文摘A wide range (9.4nm) tuning of vertically coupled microring resonator filter was demonstrated utilizing a large TO coefficient of polymer. The power consumption was about 60m W and no degradation of filter response was observed.
