The eastern foothills of the Helan Mountains in China are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the soil.This study focused on the effects of different...The eastern foothills of the Helan Mountains in China are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the soil.This study focused on the effects of different gravel contents on the water absorption characteristics and hydraulic parameters of stony soil.The stony soil samples were collected from the eastern foothills of the Helan Mountains in April 2023 and used as the experimental materials to conduct a one-dimensional horizontal soil column absorption experiment.Six experimental groups with gravel contents of 0%,10%,20%,30%,40%,and 50%were established to determine the saturated hydraulic conductivity(K_(s)),saturated water content(θ_(s)),initial water content(θ_(i)),and retention water content(θ_(r)),and explore the changes in the wetting front depth and cumulative absorption volume during the absorption experiment.The Philip model was used to fit the soil absorption process and determine the soil water absorption rate.Then the length of the characteristic wetting front depth,shape coefficient,empirical parameter,inverse intake suction and soil water suction were derived from the van Genuchten model.Finally,the hydraulic parameters mentioned above were used to fit the soil water characteristic curves,unsaturated hydraulic conductivity(K_(θ))and specific water capacity(C(h)).The results showed that the wetting front depth and cumulative absorption volume of each treatment gradually decreased with increasing gravel content.Compared with control check treatment with gravel content of 0%,soil water absorption rates in the treatments with gravel contents of 10%,20%,30%,40%,and 50%decreased by 11.47%,17.97%,25.24%,29.83%,and 42.45%,respectively.As the gravel content increased,inverse intake suction gradually increased,and shape coefficient,K_(s),θ_(s),andθ_(r)gradually decreased.For the same soil water content,soil water suction and K_(θ)gradually decreased with increasing gravel content.At the same soil water suction,C(h)decreased with increasing gravel content,and the water use efficiency worsened.Overall,the water holding capacity,hydraulic conductivity,and water use efficiency of stony soil in the eastern foothills of the Helan Mountains decreased with increasing gravel content.This study could provide data support for improving soil water use efficiency in the eastern foothills of the Helan Mountains and other similar rocky mountainous areas.展开更多
Plant tolerance to aluminum(Al)toxicity can be enhanced by an ectomycorrhizal(ECM)fungus through biological filtering or physical blockage.To understand the roles of ECM colonization in Al absorption with regard to Al...Plant tolerance to aluminum(Al)toxicity can be enhanced by an ectomycorrhizal(ECM)fungus through biological filtering or physical blockage.To understand the roles of ECM colonization in Al absorption with regard to Al tolerance,Pinus massoniana seedlings were inoculated with either Lactarius deliciosus(L.:Fr.)Gray isolate 2 or Pisolithus tinctorius(Pers.)Coker et Couch isolate 715 and cultivated in an acid yellow soil with or without 1.0 mM Al^(3+)irrigation for 10 weeks.Biomass production,Al bioaccumulation and transport in seedlings colonized by the two ECM fungi were compared,and the three absorption kinetics(pseudo-first order,pseudo-second order and intraparticle diffusion)models used to evaluate variances in root Al^(3+)absorption capacity.Results show that both fungi increased aboveground biomass and Al tolerance of P.massoniana seedlings,but L.deliciosus 2 was more effective than P.tinctorius 715.Lower Al absorption capacity,fewer available active sites and decreased affinity and boundary layer thickness for Al^(3+),and higher Al accumulation and translocation contributed to the increased Al tolerance in the ECM-inoculated seedlings.These results advance our understanding of the mechanisms and strategies in plant Alto lerance conferred by ECM fungi and show that inoculation with L.deliciosus will better enhance Al tolerance in P.massoniana seedlings used for forest plantation and ecosystem restoration in acidic soils,particularly in Southwest China and similar soils worldwide.展开更多
Many of the abandoned mining and industrial land in villages and towns are seriously polluted by heavy metals in China,it is necessary for sustainable development to adopt efficient and economical ways to restore the ...Many of the abandoned mining and industrial land in villages and towns are seriously polluted by heavy metals in China,it is necessary for sustainable development to adopt efficient and economical ways to restore the ecology of abandoned mining and industrial land.Pollution level of topsoil contaminated with metallurgical slag from nonferrous metal smelting waste site in Baoding,North China and the heavy metals(HMs)accumulation behavior of Bidens pilosa L.(B.pilosa,native pioneer plant)were studied.Two selected study sites were mainly contaminated by As(270~434 mg/kg),Cd(63~95 mg/kg),Pb(5496~24504 mg/kg)and Zn(4500~21300 mg/kg),which exceed the national standard severely.Investigation of multi-metal accumulation in different parts of B.pilosa indicated that the absorption of toxic metals varied by types,concentration and species of HMs under stress conditions,soil property and plant tissues.The results showed that B.pilosa had excellent ability to accumulate HMs under different HMs stress condition,with the highest accumulation concentration of 85 mg/kg for As,380 mg/kg for Cd,4000 mg/kg for Pb,and 7500 mg/kg for Zn in roots under experimental conditions,respectively.The growth trend of B.pilosa declined with the increase of HMs stress concentration in tested soils.HMs stress led to different degrees of plant toxicity and obstruction of physiological metabolism.Among the plant physiological index,Chla and ChlT decreased 28.0%and 28.1%,37.3%and 35.5%under different stress treatments,respectively.Indicators related to physiological metabolic strength and stress resistance of plant,such as MDA(Malondiadehyde),CAT(catalase),SOD(superoxide dismutase)and SP(soluble protein),all increased with the increase of HMs stress concentration.展开更多
The hydrogen absorption characteristics and microstructural evolution of TC21 titanium alloy were investigated by kinetic model analysis, optical microscopy （OM） and X-ray diffraction （XRD）. The results show that ...The hydrogen absorption characteristics and microstructural evolution of TC21 titanium alloy were investigated by kinetic model analysis, optical microscopy （OM） and X-ray diffraction （XRD）. The results show that the hydrogen absorption reaction occurred during the hydrogen absorption process of TC21 titanium alloy can be divided into two different stages according to the hydrogen absorption kinetics. After hydrogenation, the microstructure of TC21 titanium alloy changes obviously. Just a little hydrogen will change the contrast of transformedβphase. The contrast ofα phase darkens when the hydrogen content in TC21 titanium alloy exceeds 0.5% （mass fraction）. The phase/grain boundaries become ambiguous or even vanished, andβ phase becomes the main phase instead ofα phase when the hydrogen content reaches 0.625%. Moreover,α phase disappears when the hydrogen content reaches 1.065%. Additionally, the XRD analysis shows that α＇ martensite and FCCδ hydride appear in the hydrogenated alloy. According to the microstructures and XRD analysis, the schematic diagrams of hydrogen diffusion process in TC21 titanium alloy were established.展开更多
The non-isothermal leaching kinetics of primary titanium-rich material by microwave heating was investigated,and the temperature-pressure curves of leaching system and microwave absorption characteristics of mixture s...The non-isothermal leaching kinetics of primary titanium-rich material by microwave heating was investigated,and the temperature-pressure curves of leaching system and microwave absorption characteristics of mixture solutions before and after leaching were measured.The research of non-isothermal kinetics was evaluated by the leaching rate of Fe and the total apparent velocity equation of the non-isothermal kinetics of leaching for primary titanium-rich material by microwave heating was obtained.It is shown from the temperature-pressure curves that the high temperature and high pressure of closed leaching system are favorable to the enhancement of the leaching rate of Fe.Microwave absorption characteristics of mixture solutions before and after leaching show that there are abrupt changes of microwave absorption characteristics for 15%HCl solution and the mixture solution after leaching by 20%HCl.展开更多
This paper discusses the evolution regularity and the absorption characters of sulfide for bituminous briquette burned in a horizontal burning fornace. The evolution rate of sulphur is affected by some factors, such a...This paper discusses the evolution regularity and the absorption characters of sulfide for bituminous briquette burned in a horizontal burning fornace. The evolution rate of sulphur is affected by some factors, such as the sulphur content in the burning coal, burning time and the mean excess air coefficient in the furnace. With processing the experimental result, the calculation related expression has been obtained to predict the evolution rate of sulfide. The sulphur absorption efficiency of briquette is affected by tbe factors such as the character of the sulphur sorbent, the type of the coal and the operating parameters. By means of appropriately adjusting the calciumsulphur mole ratio, the mean excess air coefficient and the time-interval between pushing two layer briquettes, a high sulphur absorption efficiency (>74% ) can be obtained.展开更多
Objective: The intestinal absorption characteristics of active ingredients are very important for oral administration of traditional Chinese medicine(TCM) to achieve the desired therapeutic effect.However, a deeper un...Objective: The intestinal absorption characteristics of active ingredients are very important for oral administration of traditional Chinese medicine(TCM) to achieve the desired therapeutic effect.However, a deeper understanding about active ingredients absorption characteristics is still lack. The aim of this study was to investigate the absorption properties and mechanism of rhubarb active ingredients in TCM preparation and pure form.Methods: The intestinal absorption behavior of active ingredients in Shenkang extract(SKE) and rhubarb anthraquinone ingredients(RAI) were investigated by in situ single-pass intestinal perfusion model. And the bidirectional transport characteristics of these active ingredients were assessed by in vitro Caco-2 cell monolayer model.Results: In situ experiment on Sprague-Dawley rats, the effective permeability coefficient values of aloeemodin, emodin and chrysophanol in RAI were higher than those in SKE, and the value of rhein in RAI was lower than that in SKE. But the easily absorbed segments of intestine were consistent for all ingredients,whether in SKE or in RAI. In vitro experiment, the apparent permeability coefficient values of rhein, emodin and chrysophanol in RAI were higher than those in SKE, and this value of aloe-emodin in RAI was lower than that in SKE. But their efflux ratio(ER) values in SKE and RAI were all similar.Conclusion: Four rhubarb anthraquinone ingredients in SKE and RAI have similar absorption mechanism and different absorption behavior, and the microenvironment of the study models influenced their absorption behavior. The results may provide an aid for understanding of the absorption characteristics of the TCM active ingredients in complex environments and the complementarities of different research models.展开更多
An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering equipment.The impact res...An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering equipment.The impact response and the energy dissipation mechanism of hat-shaped EWMD under different quasi-static compression deformations(2-7 mm)and impact heights(100-200 mm)are investigated using experimental and numerical methods.The results demonstrate distinct stages in the quasi-static mechanical characteristics of hat-shaped EWMD,including stiffness softening,negative stiffness,and stiffness hardening.The loss factor gradually increases with increasing compression deformation before entering the stiffness hardening stage.Under impact loads,the hat-shaped EWMD exhibits optimal impact energy absorption when it enters the negative stiffness stage(150 mm),resulting in the best impact isolation effect of metallic buffer.However,the impact energy absorption significantly decreases when hat-shaped EWMD enters the stiffness hardening stage.Interestingly,quasi-static compression analysis after experiencing different impact loads reveals the disappearance of the negative stiffness phenomenon.Moreover,with increasing impact loads,the stiffness hardening point progressively shifts to an earlier stage.展开更多
In this study,interconnected porous Mg-2Zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption characteristics...In this study,interconnected porous Mg-2Zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption characteristics.Several characterization methods were then applied to identify the microstructure of the porous Mg-Zn-Y and describe the details of the second phase.Compressive tests were performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous Mg-Zn-Y.The experimental results showed that a high Y content promotes a microstructure refinement and increases the volume fraction of the second phase.When the Y content increases,different Mg-Zn-Y ternary phases appear:I-phase(Mg_(3)Zn_(6)Y),W-phase(Mg_(3)Zn_(3)Y_(2)),and LPSO phase(Mg_(12)ZnY).When the Y content ranges between 0.4%and 6%,the compressive strength increases from 6.30MPa to 9.23 MPa,and the energy absorption capacity increases from 7.33 MJ/m^(3)to 10.97 MJ/m^(3)at RT,which is mainly attributed to the phase composition and volume fraction of the second phase.However,the average energy absorption efficiency is independent of the Y content.In addition,the compressive deformation behaviors of the porous Mg-Zn-Y are altered by the testing temperature.The compressive strength and energy absorption capacity of the porous Mg-Zn-Y decrease due to the softening effect of the high temperature on the struts.The deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.展开更多
Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson’s ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure was proposed.Both the S-RH structure and AR-RH structure...Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson’s ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure was proposed.Both the S-RH structure and AR-RH structure were produced by the 3D printing technology.Through experimental test and finite element simulation,the deformation mechanism and energy absorption characteristics of the AR-RH structure and the S-RH structure with negative Poisson’s ratios at different impact velocities were compared.The experimental test and finite element simulation results show that the novel AR-RH structure with negative Poisson’s ratios has stronger energy absorption capacity than the S-RH structure,and it has been verified that the rotatability of AR-RH can indeed absorb energy.Furthermore,the degree of asymmetry of the AR-RH structure was discussed.展开更多
Based on previous work on 'Statistical absorption coefficient of microperforated absorbers', in which it was shown that theoretical results agree well with experiments on the absorption characteristics of micr...Based on previous work on 'Statistical absorption coefficient of microperforated absorbers', in which it was shown that theoretical results agree well with experiments on the absorption characteristics of microperforated absorbers (MPA) for random incidence. Further work was carried out in this investigation of the statistical absorption coefficients of MPA in random fields by computation, in order to find the best. structure of MPA. It is established that ordinarily the absorption curves of MPA for random incidence and that for normal incidence are quite alike, only that the absorption coefficients are more or less reduced and the whole curve is shifted to higher frequencies without any change of shape. But when the perforate constant k = d ωρ0/4η where d is the diameters of perforations in mm and f0, the absorbers resonance frequency is reduced below 2, say, secondary absorption bands start to play more important role. Pretty soon, they merge with the main absorption band and form a long tail of the latter,extending the absorption far into high frequencies, raising the resulting absorption band to three, four or more octaves. The behavior of the secondary absorption bands is discussed.展开更多
The absorption characteristics of radially inhomogeneous double-clad fiber (DCF) are investigated firstly with the method of caustic radius, combined with the method of WKBJ. The results are significant for double-cla...The absorption characteristics of radially inhomogeneous double-clad fiber (DCF) are investigated firstly with the method of caustic radius, combined with the method of WKBJ. The results are significant for double-clad optical fiber lasers and amplifiers.展开更多
Two infrared dyes, 1,3,3,1′, 3′, 3′ hexamethylindotricarbocyanine iodide (A) and 1,3,3,1′,3′,3′ hexamethyl 11 chloro 10,12 propylenetricarbocyanine iodide (B), were synthesized and characterized by melting...Two infrared dyes, 1,3,3,1′, 3′, 3′ hexamethylindotricarbocyanine iodide (A) and 1,3,3,1′,3′,3′ hexamethyl 11 chloro 10,12 propylenetricarbocyanine iodide (B), were synthesized and characterized by melting point, elemental analysis, IR, and 1 H NMR. Their electron absorption spectra, laser absorption characteristics and solubility were investigated. The results showed that A and B have maximum absorption peaks at around 748nm and 774nm, respectivey, which match well with the wavelength output of the near infrared laser diode. The dyes were found to have photoinduced fading during irradiation with the infrared laser, especially in the presence of oxygen. However, this procession can be greatly slowed by using a layer of poly(vinyl alcohol) to barricade the dyes from oxygen. The experiments also showed that the dyes were thermally stable but decayed under strong sunlight. Furthermore, they are easily dissolved in some common solvents.展开更多
Al Si10Mg porous protective structure often produces different damage forms under compressive loading,and these damage modes affect its protective function.In order to well meet the service requirements,there is an ur...Al Si10Mg porous protective structure often produces different damage forms under compressive loading,and these damage modes affect its protective function.In order to well meet the service requirements,there is an urgent need to comprehensively understand the mechanical behavior and response mechanism of AlSi10Mg porous structures under compressive loading.In this paper,Al Si10Mg porous structures with three kinds of volume fractions are designed and optimized to meet the requirements of high-impact,strong-energy absorption,and lightweight characteristics.The mechanical behaviors of AlSi10Mg porous structures,including the stress-strain relationship,structural bearing state,deformation and damage modes,and energy absorption characteristics,were obtained through experimental studies at different loading rates.The damage pattern of the damage section indicates that AlSi10Mg porous structures have both ductile and brittle mechanical properties.Numerical simulation studies show that the AlSi10Mg porous structure undergoes shear damage due to relative misalignment along the diagonal cross-section,and the damage location is almost at 45°to the load direction,which is the most direct cause of its structural damage,revealing the damage mechanism of AlSi10Mg porous structures under the compressive load.The normalized energy absorption model constructed in the paper well interprets the energy absorption state of Al Si10Mg porous structures and gives the sensitive location of the structures,and the results of this paper provide important references for peers in structural design and optimization.展开更多
In order to study features of rock–water interaction, a self-developed experimental system called Intelligent Testing System for Water Absorption in Deep Soft Rocks(ITSWADSR) was utilized to analyze the hydrophilic b...In order to study features of rock–water interaction, a self-developed experimental system called Intelligent Testing System for Water Absorption in Deep Soft Rocks(ITSWADSR) was utilized to analyze the hydrophilic behaviors of natural soft rock at high stress state. Combining X-ray diffraction and mercury injection test, main influencing factors on hydrophilic characteristics were studied. According to the results, it could be concluded as the following:(1) the effective porosity, and the content of illite, illite/smectite formation(S = 5%) and kaolinite have positive correlation with the water absorption capacity of rock; meanwhile, the initial moisture content, fractal dimension of effective pores, illite/smectite formation(S = 30%) and chlorite present negative correlation;(2) among the positive factors, the ascending order is kaolinite, illite/smectite formation(S = 5%) and illite;(3) the descending order among the negative factors are chlorite, illite/smectite formation(S = 30%) and fractal dimension of the effective pores;(4) influence of effective porosity on the pressurized water absorbing capacity of rock is minimal, while it is maximal in the process of no pressurized water absorption.展开更多
In this paper, argon arc plasma is chosen as an example to study the absorption characteristics of arc plasma in the infrared region. Firstly, the phase and the attenuation constants are deduced for the given temperat...In this paper, argon arc plasma is chosen as an example to study the absorption characteristics of arc plasma in the infrared region. Firstly, the phase and the attenuation constants are deduced for the given temperature, pressure and probe wavelength regions. Based on those constants, the dependence of the attenuation constant on the temperature and pressure in the vicinity of a certain probe wavelength is found. Then, theoretical analysis and discussion are conducted. Maximal absorption occurs at the position where the contributions of neutral particles and electrons come to a balance in a physical point of view, which may provide some measures to take for decreasing or controlling the plasma absorption of electromagnetic waves.展开更多
This work conducted a four-week metabolism test on rats to study the digestion and absorption characteristics of five protein-based krill products prepared from Antarctic krill as raw material.It aimed to provide theo...This work conducted a four-week metabolism test on rats to study the digestion and absorption characteristics of five protein-based krill products prepared from Antarctic krill as raw material.It aimed to provide theoretical support for the effective use of Antarctic krill protein and the development of novel protein resources.The results showed that the weight gain and true digestibility of the rats fed with krill meat,surimi and ordinary krill powder were significantly higher(P<0.05)than those of the rats fed with traditional casein.Compared to casein,proteins from the five Antarctic krill products were found to significantly improve the net protein utilization(P<0.05),and reduce the total cholesterol and triglycerides in the serum of rats(P<0.05).In summary,the Antarctic krill protein-based products with high nutritional values can be used as a potential novel protein resource in the food industry.展开更多
Graphene,as a saturable absorber(SA),has attracted much attention for its application in ultrashort pulse fiber lasers due to its ultrafast interband carrier relaxation and ultra-broadband wavelength operation.Neverth...Graphene,as a saturable absorber(SA),has attracted much attention for its application in ultrashort pulse fiber lasers due to its ultrafast interband carrier relaxation and ultra-broadband wavelength operation.Nevertheless,during the stacking process of monolayer graphene layer,the induced nonuniform contact at the interface of graphene layers deteriorate the device performance.Herein,we report the fabrication of graphene saturable absorber mirrors(SAMs)via a one-step transfer process and the realization of the much enlarged modulation depth and the much reduced nonsaturable loss with tri-layer graphene(TLG)than single-layer graphene(SLG)due to the improved uniform contact at the interface.Moreover,the operation of 1550 nm mode-locked Er-doped fiber laser with the TLG SAM exhibits excellent output characteristics of the maximum output power of 9.9 mW,a slope efficiency of 2.4%and a pulse width of 714 fs.Our findings are expected to pave the way toward high-performance ultrashort pulse fiber lasers based on graphene SAs.展开更多
The excellent response characteristics and detection sensitivity with much lower operational cost and the capability to discriminate between the isomer of some monoaromatic hydrocarbons （MAHCs） make differential opt...The excellent response characteristics and detection sensitivity with much lower operational cost and the capability to discriminate between the isomer of some monoaromatic hydrocarbons （MAHCs） make differential optical absorption spectroscopy （DOAS） a powerful tool to trace concentration variation of MAHCs. But due to the similarity in chemical structure, those MAHCs have the similar overlapped characteristic absorption structures, which make the selection of instrumental parameter critical to the accurate detection of MAHCs. Firstly, the spectral resolution used in DOAS system determines the nonlinear absorption of O2 and the mass dependence of characteristic absorption structure; thereby it determines the effect of elimination error of O2 absorption in the atmospheric spectra for the detection of MAHCs. Secondly, spectral resolution determines the differential absorption characteristics of twelve MAHCs representing major constituents in technical solvents used in the automobile industry and the interference of spectral overlapping. Thirdly, the spectral resolution determines the sensitivity, time resolution and linear range. So the spectral resolution range with the best ratio of signal to noise is used to determine the most suitable spectral resolution range, as well as the spectral resolution range that ensure the characteristic absorption structure of MAHCs and the minimization of O2 absorption interference. Finally, 0.15-0.16 nm （FWHM： full width at half maximum） is assumed to be closest to the optimum spectral resolution and it is confirmed by the results of practical measurement of MAHCs by DOAS.展开更多
In this study,a batch of indium tin oxide(ITO)/Sn composites with different ratios was obtained based on the principle of thermal evaporation by an electron beam.The crystalline structure,surface shape,and optical cha...In this study,a batch of indium tin oxide(ITO)/Sn composites with different ratios was obtained based on the principle of thermal evaporation by an electron beam.The crystalline structure,surface shape,and optical characterization of the films were researched using an X-ray diffractometer,an atomic force microscope,a UV-Vis-NIR dual-beam spectrophotometer,and an open-hole Z-scan system.By varying the relative thickness ratio of the ITO/Sn bilayer film,tunable nonlinear optical properties were achieved.The nonlinear saturation absorption coefficientβmaximum of the ITO/Sn composites is−10.5×10^(−7)cm/W,approximately 21 and 1.72 times more enhanced compared to monolayer ITO and Sn,respectively.Moreover,the improvement of the sample nonlinear performance was verified using finite-difference in temporal domain simulations.展开更多
基金funded by the National Natural Science Foundation of China(32360321)the Natural Science Foundation of Ningxia Hui Autonomous Region,China(2023AAC03046,2023AAC02018)the Ningxia Key Research and Development Project(2021BEG02011).
文摘The eastern foothills of the Helan Mountains in China are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the soil.This study focused on the effects of different gravel contents on the water absorption characteristics and hydraulic parameters of stony soil.The stony soil samples were collected from the eastern foothills of the Helan Mountains in April 2023 and used as the experimental materials to conduct a one-dimensional horizontal soil column absorption experiment.Six experimental groups with gravel contents of 0%,10%,20%,30%,40%,and 50%were established to determine the saturated hydraulic conductivity(K_(s)),saturated water content(θ_(s)),initial water content(θ_(i)),and retention water content(θ_(r)),and explore the changes in the wetting front depth and cumulative absorption volume during the absorption experiment.The Philip model was used to fit the soil absorption process and determine the soil water absorption rate.Then the length of the characteristic wetting front depth,shape coefficient,empirical parameter,inverse intake suction and soil water suction were derived from the van Genuchten model.Finally,the hydraulic parameters mentioned above were used to fit the soil water characteristic curves,unsaturated hydraulic conductivity(K_(θ))and specific water capacity(C(h)).The results showed that the wetting front depth and cumulative absorption volume of each treatment gradually decreased with increasing gravel content.Compared with control check treatment with gravel content of 0%,soil water absorption rates in the treatments with gravel contents of 10%,20%,30%,40%,and 50%decreased by 11.47%,17.97%,25.24%,29.83%,and 42.45%,respectively.As the gravel content increased,inverse intake suction gradually increased,and shape coefficient,K_(s),θ_(s),andθ_(r)gradually decreased.For the same soil water content,soil water suction and K_(θ)gradually decreased with increasing gravel content.At the same soil water suction,C(h)decreased with increasing gravel content,and the water use efficiency worsened.Overall,the water holding capacity,hydraulic conductivity,and water use efficiency of stony soil in the eastern foothills of the Helan Mountains decreased with increasing gravel content.This study could provide data support for improving soil water use efficiency in the eastern foothills of the Helan Mountains and other similar rocky mountainous areas.
基金supported by the National Natural Science Foundation of China (31570599 and 32171753)。
文摘Plant tolerance to aluminum(Al)toxicity can be enhanced by an ectomycorrhizal(ECM)fungus through biological filtering or physical blockage.To understand the roles of ECM colonization in Al absorption with regard to Al tolerance,Pinus massoniana seedlings were inoculated with either Lactarius deliciosus(L.:Fr.)Gray isolate 2 or Pisolithus tinctorius(Pers.)Coker et Couch isolate 715 and cultivated in an acid yellow soil with or without 1.0 mM Al^(3+)irrigation for 10 weeks.Biomass production,Al bioaccumulation and transport in seedlings colonized by the two ECM fungi were compared,and the three absorption kinetics(pseudo-first order,pseudo-second order and intraparticle diffusion)models used to evaluate variances in root Al^(3+)absorption capacity.Results show that both fungi increased aboveground biomass and Al tolerance of P.massoniana seedlings,but L.deliciosus 2 was more effective than P.tinctorius 715.Lower Al absorption capacity,fewer available active sites and decreased affinity and boundary layer thickness for Al^(3+),and higher Al accumulation and translocation contributed to the increased Al tolerance in the ECM-inoculated seedlings.These results advance our understanding of the mechanisms and strategies in plant Alto lerance conferred by ECM fungi and show that inoculation with L.deliciosus will better enhance Al tolerance in P.massoniana seedlings used for forest plantation and ecosystem restoration in acidic soils,particularly in Southwest China and similar soils worldwide.
基金funded by National Natural Science Foundation(Grant No.42177236)Taishan Scholars Project Foundation(tsqn202211185)+1 种基金Guangdong Basic and Applied Basic Research Foundation(Grant No.2020A1515011077)Natural Science Foundation of Shandong Province(Grant No.ZR2020MD119)。
文摘Many of the abandoned mining and industrial land in villages and towns are seriously polluted by heavy metals in China,it is necessary for sustainable development to adopt efficient and economical ways to restore the ecology of abandoned mining and industrial land.Pollution level of topsoil contaminated with metallurgical slag from nonferrous metal smelting waste site in Baoding,North China and the heavy metals(HMs)accumulation behavior of Bidens pilosa L.(B.pilosa,native pioneer plant)were studied.Two selected study sites were mainly contaminated by As(270~434 mg/kg),Cd(63~95 mg/kg),Pb(5496~24504 mg/kg)and Zn(4500~21300 mg/kg),which exceed the national standard severely.Investigation of multi-metal accumulation in different parts of B.pilosa indicated that the absorption of toxic metals varied by types,concentration and species of HMs under stress conditions,soil property and plant tissues.The results showed that B.pilosa had excellent ability to accumulate HMs under different HMs stress condition,with the highest accumulation concentration of 85 mg/kg for As,380 mg/kg for Cd,4000 mg/kg for Pb,and 7500 mg/kg for Zn in roots under experimental conditions,respectively.The growth trend of B.pilosa declined with the increase of HMs stress concentration in tested soils.HMs stress led to different degrees of plant toxicity and obstruction of physiological metabolism.Among the plant physiological index,Chla and ChlT decreased 28.0%and 28.1%,37.3%and 35.5%under different stress treatments,respectively.Indicators related to physiological metabolic strength and stress resistance of plant,such as MDA(Malondiadehyde),CAT(catalase),SOD(superoxide dismutase)and SP(soluble protein),all increased with the increase of HMs stress concentration.
基金Project(51205102)supported by the National Natural Science Foundation of ChinaProject(2012M511401)supported by the Postdoctoral Science Foundation of China
文摘The hydrogen absorption characteristics and microstructural evolution of TC21 titanium alloy were investigated by kinetic model analysis, optical microscopy （OM） and X-ray diffraction （XRD）. The results show that the hydrogen absorption reaction occurred during the hydrogen absorption process of TC21 titanium alloy can be divided into two different stages according to the hydrogen absorption kinetics. After hydrogenation, the microstructure of TC21 titanium alloy changes obviously. Just a little hydrogen will change the contrast of transformedβphase. The contrast ofα phase darkens when the hydrogen content in TC21 titanium alloy exceeds 0.5% （mass fraction）. The phase/grain boundaries become ambiguous or even vanished, andβ phase becomes the main phase instead ofα phase when the hydrogen content reaches 0.625%. Moreover,α phase disappears when the hydrogen content reaches 1.065%. Additionally, the XRD analysis shows that α＇ martensite and FCCδ hydride appear in the hydrogenated alloy. According to the microstructures and XRD analysis, the schematic diagrams of hydrogen diffusion process in TC21 titanium alloy were established.
基金Project(2007CB613606)supported by the National Basic Research Program of China
文摘The non-isothermal leaching kinetics of primary titanium-rich material by microwave heating was investigated,and the temperature-pressure curves of leaching system and microwave absorption characteristics of mixture solutions before and after leaching were measured.The research of non-isothermal kinetics was evaluated by the leaching rate of Fe and the total apparent velocity equation of the non-isothermal kinetics of leaching for primary titanium-rich material by microwave heating was obtained.It is shown from the temperature-pressure curves that the high temperature and high pressure of closed leaching system are favorable to the enhancement of the leaching rate of Fe.Microwave absorption characteristics of mixture solutions before and after leaching show that there are abrupt changes of microwave absorption characteristics for 15%HCl solution and the mixture solution after leaching by 20%HCl.
文摘This paper discusses the evolution regularity and the absorption characters of sulfide for bituminous briquette burned in a horizontal burning fornace. The evolution rate of sulphur is affected by some factors, such as the sulphur content in the burning coal, burning time and the mean excess air coefficient in the furnace. With processing the experimental result, the calculation related expression has been obtained to predict the evolution rate of sulfide. The sulphur absorption efficiency of briquette is affected by tbe factors such as the character of the sulphur sorbent, the type of the coal and the operating parameters. By means of appropriately adjusting the calciumsulphur mole ratio, the mean excess air coefficient and the time-interval between pushing two layer briquettes, a high sulphur absorption efficiency (>74% ) can be obtained.
基金supported by the National Natural Science Foundation of China (No. 81673397)the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2020JM-023)。
文摘Objective: The intestinal absorption characteristics of active ingredients are very important for oral administration of traditional Chinese medicine(TCM) to achieve the desired therapeutic effect.However, a deeper understanding about active ingredients absorption characteristics is still lack. The aim of this study was to investigate the absorption properties and mechanism of rhubarb active ingredients in TCM preparation and pure form.Methods: The intestinal absorption behavior of active ingredients in Shenkang extract(SKE) and rhubarb anthraquinone ingredients(RAI) were investigated by in situ single-pass intestinal perfusion model. And the bidirectional transport characteristics of these active ingredients were assessed by in vitro Caco-2 cell monolayer model.Results: In situ experiment on Sprague-Dawley rats, the effective permeability coefficient values of aloeemodin, emodin and chrysophanol in RAI were higher than those in SKE, and the value of rhein in RAI was lower than that in SKE. But the easily absorbed segments of intestine were consistent for all ingredients,whether in SKE or in RAI. In vitro experiment, the apparent permeability coefficient values of rhein, emodin and chrysophanol in RAI were higher than those in SKE, and this value of aloe-emodin in RAI was lower than that in SKE. But their efflux ratio(ER) values in SKE and RAI were all similar.Conclusion: Four rhubarb anthraquinone ingredients in SKE and RAI have similar absorption mechanism and different absorption behavior, and the microenvironment of the study models influenced their absorption behavior. The results may provide an aid for understanding of the absorption characteristics of the TCM active ingredients in complex environments and the complementarities of different research models.
基金the financial support by the National Natural Science Foundation of China(No.12272094)the Natural Science Foundation of Fujian Province of China(No.2022J01541)Natural Science Foundation of Hubei Province of China(No.2022CFB441)。
文摘An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering equipment.The impact response and the energy dissipation mechanism of hat-shaped EWMD under different quasi-static compression deformations(2-7 mm)and impact heights(100-200 mm)are investigated using experimental and numerical methods.The results demonstrate distinct stages in the quasi-static mechanical characteristics of hat-shaped EWMD,including stiffness softening,negative stiffness,and stiffness hardening.The loss factor gradually increases with increasing compression deformation before entering the stiffness hardening stage.Under impact loads,the hat-shaped EWMD exhibits optimal impact energy absorption when it enters the negative stiffness stage(150 mm),resulting in the best impact isolation effect of metallic buffer.However,the impact energy absorption significantly decreases when hat-shaped EWMD enters the stiffness hardening stage.Interestingly,quasi-static compression analysis after experiencing different impact loads reveals the disappearance of the negative stiffness phenomenon.Moreover,with increasing impact loads,the stiffness hardening point progressively shifts to an earlier stage.
基金supported by"The National Key Research and Development Program of China(No.2018 YFA0703300)""Science and Technology Project of Education Department of Jilin Province(No.JJKH20231086KJ)"Development Project of Jilin Province(No.2021C038-4)。
文摘In this study,interconnected porous Mg-2Zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption characteristics.Several characterization methods were then applied to identify the microstructure of the porous Mg-Zn-Y and describe the details of the second phase.Compressive tests were performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous Mg-Zn-Y.The experimental results showed that a high Y content promotes a microstructure refinement and increases the volume fraction of the second phase.When the Y content increases,different Mg-Zn-Y ternary phases appear:I-phase(Mg_(3)Zn_(6)Y),W-phase(Mg_(3)Zn_(3)Y_(2)),and LPSO phase(Mg_(12)ZnY).When the Y content ranges between 0.4%and 6%,the compressive strength increases from 6.30MPa to 9.23 MPa,and the energy absorption capacity increases from 7.33 MJ/m^(3)to 10.97 MJ/m^(3)at RT,which is mainly attributed to the phase composition and volume fraction of the second phase.However,the average energy absorption efficiency is independent of the Y content.In addition,the compressive deformation behaviors of the porous Mg-Zn-Y are altered by the testing temperature.The compressive strength and energy absorption capacity of the porous Mg-Zn-Y decrease due to the softening effect of the high temperature on the struts.The deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.
基金This work is supported by the State Key for Strength and Vibration of Mechanical Structures of Xi’an Jiaotong University(No.SV2018-KF-32)the Natural Science Foundation of Guangdong Province of China(2020A1515011064).
文摘Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson’s ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure was proposed.Both the S-RH structure and AR-RH structure were produced by the 3D printing technology.Through experimental test and finite element simulation,the deformation mechanism and energy absorption characteristics of the AR-RH structure and the S-RH structure with negative Poisson’s ratios at different impact velocities were compared.The experimental test and finite element simulation results show that the novel AR-RH structure with negative Poisson’s ratios has stronger energy absorption capacity than the S-RH structure,and it has been verified that the rotatability of AR-RH can indeed absorb energy.Furthermore,the degree of asymmetry of the AR-RH structure was discussed.
文摘Based on previous work on 'Statistical absorption coefficient of microperforated absorbers', in which it was shown that theoretical results agree well with experiments on the absorption characteristics of microperforated absorbers (MPA) for random incidence. Further work was carried out in this investigation of the statistical absorption coefficients of MPA in random fields by computation, in order to find the best. structure of MPA. It is established that ordinarily the absorption curves of MPA for random incidence and that for normal incidence are quite alike, only that the absorption coefficients are more or less reduced and the whole curve is shifted to higher frequencies without any change of shape. But when the perforate constant k = d ωρ0/4η where d is the diameters of perforations in mm and f0, the absorbers resonance frequency is reduced below 2, say, secondary absorption bands start to play more important role. Pretty soon, they merge with the main absorption band and form a long tail of the latter,extending the absorption far into high frequencies, raising the resulting absorption band to three, four or more octaves. The behavior of the secondary absorption bands is discussed.
基金This work was supported by the National Science Foundation of China (60277025)
文摘The absorption characteristics of radially inhomogeneous double-clad fiber (DCF) are investigated firstly with the method of caustic radius, combined with the method of WKBJ. The results are significant for double-clad optical fiber lasers and amplifiers.
文摘Two infrared dyes, 1,3,3,1′, 3′, 3′ hexamethylindotricarbocyanine iodide (A) and 1,3,3,1′,3′,3′ hexamethyl 11 chloro 10,12 propylenetricarbocyanine iodide (B), were synthesized and characterized by melting point, elemental analysis, IR, and 1 H NMR. Their electron absorption spectra, laser absorption characteristics and solubility were investigated. The results showed that A and B have maximum absorption peaks at around 748nm and 774nm, respectivey, which match well with the wavelength output of the near infrared laser diode. The dyes were found to have photoinduced fading during irradiation with the infrared laser, especially in the presence of oxygen. However, this procession can be greatly slowed by using a layer of poly(vinyl alcohol) to barricade the dyes from oxygen. The experiments also showed that the dyes were thermally stable but decayed under strong sunlight. Furthermore, they are easily dissolved in some common solvents.
基金financially supported by the National Natural Science Foundation of China(Nos.12272356,12072326,and 12172337)the State Key Laboratory of Dynamic Measurement Technology,North University of China(No.2022-SYSJJ-03)。
文摘Al Si10Mg porous protective structure often produces different damage forms under compressive loading,and these damage modes affect its protective function.In order to well meet the service requirements,there is an urgent need to comprehensively understand the mechanical behavior and response mechanism of AlSi10Mg porous structures under compressive loading.In this paper,Al Si10Mg porous structures with three kinds of volume fractions are designed and optimized to meet the requirements of high-impact,strong-energy absorption,and lightweight characteristics.The mechanical behaviors of AlSi10Mg porous structures,including the stress-strain relationship,structural bearing state,deformation and damage modes,and energy absorption characteristics,were obtained through experimental studies at different loading rates.The damage pattern of the damage section indicates that AlSi10Mg porous structures have both ductile and brittle mechanical properties.Numerical simulation studies show that the AlSi10Mg porous structure undergoes shear damage due to relative misalignment along the diagonal cross-section,and the damage location is almost at 45°to the load direction,which is the most direct cause of its structural damage,revealing the damage mechanism of AlSi10Mg porous structures under the compressive load.The normalized energy absorption model constructed in the paper well interprets the energy absorption state of Al Si10Mg porous structures and gives the sensitive location of the structures,and the results of this paper provide important references for peers in structural design and optimization.
文摘In order to study features of rock–water interaction, a self-developed experimental system called Intelligent Testing System for Water Absorption in Deep Soft Rocks(ITSWADSR) was utilized to analyze the hydrophilic behaviors of natural soft rock at high stress state. Combining X-ray diffraction and mercury injection test, main influencing factors on hydrophilic characteristics were studied. According to the results, it could be concluded as the following:(1) the effective porosity, and the content of illite, illite/smectite formation(S = 5%) and kaolinite have positive correlation with the water absorption capacity of rock; meanwhile, the initial moisture content, fractal dimension of effective pores, illite/smectite formation(S = 30%) and chlorite present negative correlation;(2) among the positive factors, the ascending order is kaolinite, illite/smectite formation(S = 5%) and illite;(3) the descending order among the negative factors are chlorite, illite/smectite formation(S = 30%) and fractal dimension of the effective pores;(4) influence of effective porosity on the pressurized water absorbing capacity of rock is minimal, while it is maximal in the process of no pressurized water absorption.
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 10804052)the Postgraduate Innovation Foundation of Jiangsu Provincethe Key Postgraduate Planting Plan of Nanjing University of Science and Technology,China
文摘In this paper, argon arc plasma is chosen as an example to study the absorption characteristics of arc plasma in the infrared region. Firstly, the phase and the attenuation constants are deduced for the given temperature, pressure and probe wavelength regions. Based on those constants, the dependence of the attenuation constant on the temperature and pressure in the vicinity of a certain probe wavelength is found. Then, theoretical analysis and discussion are conducted. Maximal absorption occurs at the position where the contributions of neutral particles and electrons come to a balance in a physical point of view, which may provide some measures to take for decreasing or controlling the plasma absorption of electromagnetic waves.
基金financially supported by the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2022 QNLM030002)the National Key R&D Program of China‘Formation Mechanism of Antarctic Krill Fishery and Key Technologies for Efficient Utilization of Resources’:Antarctic Krill High Value Product Creation and Industrialization Demonstration(No.2018YFC1406806)the Technology Innovation Project of Qingdao Marine Science and Technology Pilot National Laboratory,Shandong Provincial Marine Science,the Technology Fund Major‘Dark Blue Fishery’4-2:Construction of Antarctic Krill Processing Technology Process System(No.2018SDKJ0304-2)。
文摘This work conducted a four-week metabolism test on rats to study the digestion and absorption characteristics of five protein-based krill products prepared from Antarctic krill as raw material.It aimed to provide theoretical support for the effective use of Antarctic krill protein and the development of novel protein resources.The results showed that the weight gain and true digestibility of the rats fed with krill meat,surimi and ordinary krill powder were significantly higher(P<0.05)than those of the rats fed with traditional casein.Compared to casein,proteins from the five Antarctic krill products were found to significantly improve the net protein utilization(P<0.05),and reduce the total cholesterol and triglycerides in the serum of rats(P<0.05).In summary,the Antarctic krill protein-based products with high nutritional values can be used as a potential novel protein resource in the food industry.
基金supported by the Key Research and Development Plan of Ministry of Science and Technology(2016YFB0402303)National Natural Science Foundation of China(NSFC)(61875222,61605106)China Postdoctoral Science Foundation(2017M621858)
文摘Graphene,as a saturable absorber(SA),has attracted much attention for its application in ultrashort pulse fiber lasers due to its ultrafast interband carrier relaxation and ultra-broadband wavelength operation.Nevertheless,during the stacking process of monolayer graphene layer,the induced nonuniform contact at the interface of graphene layers deteriorate the device performance.Herein,we report the fabrication of graphene saturable absorber mirrors(SAMs)via a one-step transfer process and the realization of the much enlarged modulation depth and the much reduced nonsaturable loss with tri-layer graphene(TLG)than single-layer graphene(SLG)due to the improved uniform contact at the interface.Moreover,the operation of 1550 nm mode-locked Er-doped fiber laser with the TLG SAM exhibits excellent output characteristics of the maximum output power of 9.9 mW,a slope efficiency of 2.4%and a pulse width of 714 fs.Our findings are expected to pave the way toward high-performance ultrashort pulse fiber lasers based on graphene SAs.
文摘The excellent response characteristics and detection sensitivity with much lower operational cost and the capability to discriminate between the isomer of some monoaromatic hydrocarbons （MAHCs） make differential optical absorption spectroscopy （DOAS） a powerful tool to trace concentration variation of MAHCs. But due to the similarity in chemical structure, those MAHCs have the similar overlapped characteristic absorption structures, which make the selection of instrumental parameter critical to the accurate detection of MAHCs. Firstly, the spectral resolution used in DOAS system determines the nonlinear absorption of O2 and the mass dependence of characteristic absorption structure; thereby it determines the effect of elimination error of O2 absorption in the atmospheric spectra for the detection of MAHCs. Secondly, spectral resolution determines the differential absorption characteristics of twelve MAHCs representing major constituents in technical solvents used in the automobile industry and the interference of spectral overlapping. Thirdly, the spectral resolution determines the sensitivity, time resolution and linear range. So the spectral resolution range with the best ratio of signal to noise is used to determine the most suitable spectral resolution range, as well as the spectral resolution range that ensure the characteristic absorption structure of MAHCs and the minimization of O2 absorption interference. Finally, 0.15-0.16 nm （FWHM： full width at half maximum） is assumed to be closest to the optimum spectral resolution and it is confirmed by the results of practical measurement of MAHCs by DOAS.
基金supported by the National Natural Science Foundation of China(Nos.61775141 and 62075133).
文摘In this study,a batch of indium tin oxide(ITO)/Sn composites with different ratios was obtained based on the principle of thermal evaporation by an electron beam.The crystalline structure,surface shape,and optical characterization of the films were researched using an X-ray diffractometer,an atomic force microscope,a UV-Vis-NIR dual-beam spectrophotometer,and an open-hole Z-scan system.By varying the relative thickness ratio of the ITO/Sn bilayer film,tunable nonlinear optical properties were achieved.The nonlinear saturation absorption coefficientβmaximum of the ITO/Sn composites is−10.5×10^(−7)cm/W,approximately 21 and 1.72 times more enhanced compared to monolayer ITO and Sn,respectively.Moreover,the improvement of the sample nonlinear performance was verified using finite-difference in temporal domain simulations.
