Recently,an article was published on solid effect(SE)dynamic nuclear polarization(DNP)enhancement,where the au-thors reported achieving 1H enhancement factors up to 500 by increasing the microwave power at 9.4 T,marki...Recently,an article was published on solid effect(SE)dynamic nuclear polarization(DNP)enhancement,where the au-thors reported achieving 1H enhancement factors up to 500 by increasing the microwave power at 9.4 T,marking the highest SE enhancement to date[1].展开更多
Based on the properties of antimony(Sb)and arsenic(As),a method was proposed to enhance gold recovery during iron matte smelting.The impact of Sb and As on gold enhancement capture was investigated using an exclusion ...Based on the properties of antimony(Sb)and arsenic(As),a method was proposed to enhance gold recovery during iron matte smelting.The impact of Sb and As on gold enhancement capture was investigated using an exclusion method.The results demonstrated that both Sb and As significantly improved the gold recovery rate.As the Sb or As content increased,the gold recovery rate increased.The enhancement effect of Sb was better than that of As,and the optimal results were achieved through the synergistic effects of Sb and As.Under optimized conditions,the gold recovery rate reached 97.12%,whereas the gold content in the slag decreased to 1.70 g/t.Sb captured and aggregated free gold as an Au-Sb alloy,whereas As-Fe alloy also captured free gold.The growth of the gold-captured phase size enhanced the settling velocity,thereby promoting gold recovery.展开更多
To elucidate the yielding performance of compact yielding anchor cables in working state,a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed.The ...To elucidate the yielding performance of compact yielding anchor cables in working state,a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed.The yielding resistance enhancement effect(ω)caused by working environment constraints is evaluated through multi-layer composite sleeve hole expansion analysis,forming a theoretical framework for calculating the working yielding force.Laboratory and in-situ pull-out tests are conducted to determine the yielding performance and validate the analytical theory.The main conclusions are:(1)Yielding force and energy-release capacity increase withω,significantly outperforming the unconfined state.(2)In-situ tests under varying rockmass and geostress conditions(F1–F3)determine the yielding force increases to 183.4–290.1,204.0–290.8,and 235.0–327.1 kN.(3)The slight deviation(–12.5%to 6.2%)between the theoretical and measured yielding force confirms that the analytical theory effectively describes the working yielding performance.(4)ωincreases with higher geostress and improved rock mechanical properties,with initial geostress(σ_(0))and elastic modulus of surrounding rock(E_(3))identified as critical parameters.展开更多
In the field of soil stabilization, only calcium silicate hydrate(CSH) and ettringite(AFt) as hydration products have been reported to directly contribute to the strength enhancement of the soil. A chloride dredger fi...In the field of soil stabilization, only calcium silicate hydrate(CSH) and ettringite(AFt) as hydration products have been reported to directly contribute to the strength enhancement of the soil. A chloride dredger fill, an artificial chloride saline soil, and a non-saline soil were stabilized by Portland cement(PC) and PC with Ca(OH)_2(CH) with different contents. A series of unconfined compressive strength(UCS) tests of stabilized soil specimen after curing for 7 d and 28 d were carried out, and the hydration products and microstructure of the specimens were observed by X-ray diffractometry(XRD), scanning electronic microscopy(SEM), and energy-dispersive X-ray analysis(EDXA). The results showed that the strengths of PC+CH-stabilized chloride saline soils were much higher than those of PC-stabilized soils. A new hydration product of calcium aluminate chloride hydrate, also known as Friedel's salt, appeared in the PC+CH-stabilized chloride saline soils. The solid-phase volume of Friedel's salt expanded during the formation of the hydrate; this volume filled the pores in the stabilized soil. This pore-filling effect was the most important contribution to the significantly enhanced strength of the PC+CH-stabilized chloride saline soils. On the basis of this understanding, a new optimized stabilizer was designed according to the concept that the chloride in saline soil could be utilized as a component of the stabilizer. The strength of the chloride saline soils stabilized by the optimized stabilizer was even further increased compared with that of the PC+CH-stabilized soils.展开更多
In this paper, modifications to the finite-difference time-domain(FD-TD) method for modeling microwave pulse coupling into a slot, which is much narrower than one conventional FD-TD cell, are discussed. The coupling p...In this paper, modifications to the finite-difference time-domain(FD-TD) method for modeling microwave pulse coupling into a slot, which is much narrower than one conventional FD-TD cell, are discussed. The coupling process of microwave pulse into a slot is studied by using the modified FD-TD method, and the dependence of microwave coupling on slot sizes, the carrier frequencies and the polarization directions of the incident waves is analysed. Resonant and enhancement effects which occur in this process are observed. The condition at which the resonant effect takes place is also presented.展开更多
Integral thin shells made of high strength aluminum alloys are urgently needed in new generation transportation equipment. There are challenges to overcoming the co-existing problems of wrinkling and splitting by the ...Integral thin shells made of high strength aluminum alloys are urgently needed in new generation transportation equipment. There are challenges to overcoming the co-existing problems of wrinkling and splitting by the cold forming and hot forming processes. An innovative technology of ultra-low temperature forming has been invented for aluminum alloy thin shells by the new phenomenon of ‘dual enhancement effect’. That means plasticity and hardening are enhanced simultaneously at ultra-low temperatures. In this perspective, the dual enhancement effect is described, and the development, current state and prospects of this new forming method are introduced. This innovative method can provide a new approach for integral aluminum alloy components with large size, ultra-thin thickness, and high strength. An integral tank dome of rocket with 2 m in diameter was formed by using a blank sheet with the same thickness as the final component, breaking through the limit value of thickness-diameter ratio.展开更多
On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular ...On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular tube,which is inherently induced by the closed propagation feature of CGWs.An appropriate mode pair of primary-and double-frequency CGWs satisfying the phase velocity matching and nonzero energy flux is selected to ensure that the second harmonic generated by primary CGW propagation can accumulate along the circumference.Using a coherent superposition of multi-waves,a model of unidirectional CGW propagation is established for analyzing the enhancement effect of cumulative SHG of primary CGW mode selected.The theoretical analyses and numerical simulations performed directly demonstrate that the second harmonic generated does have a cumulative effect along the circumferential direction and the closed propagation feature of CGWs does enhance the magnitude of cumulative second harmonic generated.Potential applications of the enhancement effect of cumulative SHG of CGWs are considered and discussed.The theoretical analysis and numerical simulation perspective presented here yield an insight previously unavailable into the physical mechanism of the enhancement effect of cumulative SHG by closed propagation feature of CGWs in a circular tube.展开更多
Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole...Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole approximation （DDA）,we study the absorption and scattering properties of two-dimensional square silver nanodisks （2D SSN） arrays on the single crystal silicon solar cell.Based on the effective reflective index model of the single crystal silicon solar cell,we investigate the optical enhancement absorption of light energy by varying the light incident direction,particle size,aspect ratio,and interparticle spacing of the silver nanodisks.The peak values and position of the optical extinction spectra of the 2D square arrays of noble metal nanodisks are obtained with the different array structures.展开更多
Artificial fish nests are set in Lukou section and Hengyang section of Xiangjiang River from March 20 to May 10, 2019. The structure of artificial fish nest is bamboo frame, with the size of 2.5 m × 5.0 m × ...Artificial fish nests are set in Lukou section and Hengyang section of Xiangjiang River from March 20 to May 10, 2019. The structure of artificial fish nest is bamboo frame, with the size of 2.5 m × 5.0 m × 4 and a unit frame area of 60 m<sup>2</sup>. A total of 58,201 eggs were collected by 24 monitoring times, of which 30,441 were from Lukou and 27,760 from Hengyang. 3831 fish eggs identify 8 fish species using morphological or molecular biological methods. The results showed that the number of eggs peaked from the 8<sup>th</sup> day to the 24<sup>th</sup> day after the nest entered the water, and then decreased rapidly. There was significant negative correlation between egg number in per m<sup>2</sup> fish nest and days of fish nest (P < 0.01). The economic benefits of artificial fish nests were RMB 11.81 million. The artificial fish nest can not only increase the population of fish, but also has significant economic benefits.展开更多
An orthogonal ultrasonic irradiation system consisting of HIFU with frequency at 1.05 MHz combined with ultrasound with frequency at 28 kHz was applied in this paper.Effect of cavitation was detected by pH-value measu...An orthogonal ultrasonic irradiation system consisting of HIFU with frequency at 1.05 MHz combined with ultrasound with frequency at 28 kHz was applied in this paper.Effect of cavitation was detected by pH-value measurement and conductance measurement.The result shows that the effect of cavitation caused by ultrasound with frequency at 28 kHz is greatly enhanced by HIFU piezoelectricity transducer with frequency at 1.05 MHz.展开更多
The luminescent enhancement effect of Na_5Eu(MoO_4)_4 by doping(WO_4)^(2-) has been studied. When the value x in Na_5Eu(Mo_(1-x)W_xO_4)_4 is in 0<x<0.21,its photoluminescent spectrum is near to that of Na_5Eu(Mo...The luminescent enhancement effect of Na_5Eu(MoO_4)_4 by doping(WO_4)^(2-) has been studied. When the value x in Na_5Eu(Mo_(1-x)W_xO_4)_4 is in 0<x<0.21,its photoluminescent spectrum is near to that of Na_5Eu(MoO_4)_4,but its luminescent intensity increases.When x=0.033,the intensity is increased by about 30%.According to the X-ray diffraction analysis,W ions get into the lattice and occupy the sites of the Mo ions.The change of crystal environment of Eu^(3+) may result in the luminescent enhancement.展开更多
This study investigated the enhancement effects of dissolved carbonates on the peroxymonosulfate-based advanced oxidation process with CuS as a catalyst.It was found that the added CO_(3)^(2−)increased both the cataly...This study investigated the enhancement effects of dissolved carbonates on the peroxymonosulfate-based advanced oxidation process with CuS as a catalyst.It was found that the added CO_(3)^(2−)increased both the catalytic activity and the stability of the catalyst.Under optimized reaction conditions in the presence of CO_(3)^(2−),the degradation removal of 4-methylphenol(4-MP)within 2 min reached 100%,and this was maintained in consecutivemulti-cycle experiments.The degradation rate constant of 4-MP was 2.159 min^(−1),being 685%greater than that in the absence of CO_(3)^(2−)(0.315 min−1).The comparison of dominated active species and 4-MP degradation pathways in both CO_(3)^(2−)-free and CO_(3)^(2−)-containing systems suggested thatmore CO_(3)·^(−)/^(1)O_(2) was produced in the case of CO_(3)^(2−)deducing an electron transfer medium,which tending to react with electron-richmoieties.Meanwhile,Characterization by X-ray photoelectron spectroscopic and cyclic voltammetrymeasurement verified CO_(3)^(2−)enabled the effective reduction of Cu^(2+)to Cu^(+).By investigating the degradation of 11 phenolics with different substituents,the dependence of degradation kinetic rate constant of the phenolics on their chemical structures indicated that there was a good linear relationship between the Hammett constantsσp of the aromatic phenolics and the logarithm of k in the CO_(3)^(2−)-containing system.This work provides a new strategy for efficient removal of electron-rich moieties under the driving of carbonate being widely present in actual water bodies.展开更多
The stock enhancement programs for black sea bream Acanthopagrus schlegelii have been conducted in China for a fewyears.However,little information has been reported concerning the effectiveness and genetic effect of b...The stock enhancement programs for black sea bream Acanthopagrus schlegelii have been conducted in China for a fewyears.However,little information has been reported concerning the effectiveness and genetic effect of black sea bream stock enhancement.In order to detect the contribution of released individuals in Zhujiang River Estuary(ZRE)and Daya Bay(DB),six microsatellite markers were used to identify the hatchery-released individuals.In addition,this pedigree of hatchery populations(broodfish and hatchery-released offspring)was traced to detect the number of effective parents(N_(e)),the inbreeding coefficient and the decrease of genetic variability in the reproduction.The pedigree reconstruction showed that at least 69(out of 93)broodfish had offspring.The estimated N_(e) was 54.8,consequently the inbreeding coefficient was 0.91%.The genetic diversity of hatchery-released offspring was lower than that in that of broodfish(heterozygosity alleles,0.727-0.774),some alleles(number of alleles,61-69)and genetic variance were lost during reproduction.It was observed that wild samples had higher levels of genetic diversity compared with hatchery populations as well as recaptured samples in releasing area.A total of 128 hatchery-released black sea bream were identified among 487 recaptured samples in ZRE,while a total of 15 samples were identified among 96 samples in DB.In summary,there was a high survival of released fish.N_(e)vertheless,the results provided evidence to consider a loss of genetic variation in hatcheryreleased stock and a negative genetic effect of the stock enhancement.展开更多
Influenced by recent COVID-19,wearing face masks to block the spread of the epidemic has become the simplest and most effective way.However,after the people wear masks,thousands of tons of medical waste by used dis-po...Influenced by recent COVID-19,wearing face masks to block the spread of the epidemic has become the simplest and most effective way.However,after the people wear masks,thousands of tons of medical waste by used dis-posable masks will be generated every day in the world,causing great pressure on the environment.Herein,con-ductive polymer composites are fabricated by simple melt blending of mask fragments(mask polypropylene,short for mPP)and multi-walled carbon nanotubes(MWNTs).MWNTs were used as modifiers for composites because of their high strength and high conductivity.The crystalline structure,mechanical,electrical and thermal enhancement effect of the composites were investigated.MWNTs with high thermal stability acted the role of promoting the crystallisation of mPP by expediting the crystalline nucleation,leading to the improvement of amount for crystalline nucleus.MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network.With 2.0 wt% MWNTs loading,the tensile strength and electrical conductivity of the composites were increased by 809% and 7 orders of magnitude.MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network.Thus,more conducting paths were constructed to transport carriers.The findings may open a way for high value utilization of the disposable masks.展开更多
The kagome ferrimagnet TbMn_(6)Sn_(6),featuring a pristine Mn kagome lattice,has emerged as a candidate Chern magnet with a large intrinsic anomalous Hall effect(AHE).While chemical substitution can modulate its prope...The kagome ferrimagnet TbMn_(6)Sn_(6),featuring a pristine Mn kagome lattice,has emerged as a candidate Chern magnet with a large intrinsic anomalous Hall effect(AHE).While chemical substitution can modulate its properties,hydrostatic pressure provides a disorder-free route to manipulate electronic and magnetic interactions.Herein,we investigate the effects of hydrostatic pressure on electrical and magneto-transport in TbMn6Sn6 up to 18.3 GPa.Pressure significantly enhances hysteresis in the magnetoresistance and Hall responses,causing a concurrent monotonic coercive field increase,suggesting the enhancement of interlayer magnetic couplings in a robust c-axis ferrimagnetic order.The intrinsic anomalous Hall conductivity increases considerably from 129.5 S·cm^(−1) at ambient pressure conditions to 448.7 S·cm^(−1) at 14.0 GPa—an enhancement of 247%that is unprecedented among pressure-tuned kagome magnets.Based on density functional theory calculations,we reveal that pressure induces multiple gap openings near the Fermi level,giving rise to pronounced Berry curvature hotspots that may contribute to the AHE.Our results show that pressure can be used to enhance the intrinsic topological responses of this kagome magnet.展开更多
The dominant property of building envelope fabric which contributes significantly to minimize electricity utilization in building is the thermo-physical properties. There is inadequate literature on representative pra...The dominant property of building envelope fabric which contributes significantly to minimize electricity utilization in building is the thermo-physical properties. There is inadequate literature on representative practical data of thermo-physical properties of the dominant building envelope components in Ghana. This study aims to use cost-effective approach to characterize the thermo-physical properties of only cement-based mortar and concrete blocks used in Ghana for building components specifically wall design. Mixed methods research design was employed to achieving the aim. A questionnaire survey was used among sampled building fabric components manufacturers to pick representative data on thermos-physical properties of their mortar and concrete blocks. Also, an experimental procedure employing a transient technique with a TCi Thermal Analyser was used to determine the thermo-physical properties of selected mortar and concrete blocks from Ghana in addition to designed parametric mortar and concrete blocks with varied ratios obtained from the survey were undertaken at University of Nottingham. From the study, a trend of decreasing thermal conductivity and thermal effusivity with corresponding decreasing sand content was observed with all the different sand types. The thermal conductivities of both mortar and concrete parametric blocks meet the range of expected standard values outlined in Chattered Institute of Building Services Engineers (CIBSE) Guide A. The major limitation of the work is the dimension of the sample size;which is not inconsistent with standard block size due to the experimental setup used. It is expected that, the characterization of the predominant cement-based building fabrics components will contribute to improved building performance analysis with significant savings in electricity utilization for space cooling.展开更多
In terms of the reaction of COreduction to CO with hydrogen, COconversion is very low at low temperature due to the limitation of thermodynamic equilibrium（TE）. To overcome this limitation, plasma catalytic reductio...In terms of the reaction of COreduction to CO with hydrogen, COconversion is very low at low temperature due to the limitation of thermodynamic equilibrium（TE）. To overcome this limitation, plasma catalytic reduction of COto CO in a catalyst-filled dielectric barrier discharge（DBD） reactor is studied. An enhanced effect of plasma on the reaction over Au/CeOcatalysts is observed. For both the conventionally catalytic（CC） and plasma catalytic（PC, Pin= 15 W） reactions under conditions of 400 °C, H/CO= 1,200 SCCM, GHSV = 12,000 mL·gcat·h, COconversions over Au/CeOreach 15.4% and 25.5% due to the presence of Au, respectively, however, those over CeOare extremely low and negligible. Moreover,COconversion over Au/CeOin the PC reaction exceeds 22.4% of the TE conversion. Surface intermediate species formed on the catalyst samples during the reactions are determined by in-situ temperatureprogrammed decomposition（TPD） technique. Interestingly, it disclosed that in the PC reaction, the formation of formate intermediate is enhanced by plasma, and the acceleration by plasma in the decomposition of formate species is much greater than that in the formation of formate species on Au/CeO. Enhancement factor is introduced to quantify the enhanced effect of plasma. Lower reactor temperature, higher gas hourly space velocity（GHSV）, and lower molar ratio of H/COwould be associated with larger enhancement factor.展开更多
The Dual Synthetic Jet Actuator(DSJA) is used to develop a new type of lift enhancement device based on circulation control, and to control the flow over the two-dimensional(2D)NACA0015 airfoil. The lift enhancement d...The Dual Synthetic Jet Actuator(DSJA) is used to develop a new type of lift enhancement device based on circulation control, and to control the flow over the two-dimensional(2D)NACA0015 airfoil. The lift enhancement device is composed of a DSJA and a rounded trailing edge(Coanda surface). The two outlets of the DSJA eject two jets(Jet 1 and Jet 2). Jet 1 ejects from the upper trailing edge, which increases the circulation of airfoil with the help of the Coanda surface. Jet2 ejects from the lower trailing edge, which acts as a virtual flap. The Reynolds number based on the airfoil chord length and free flow velocity is 250000. The results indicate that the circulation control method based on Dual Synthetic Jet(DSJ) has good performance in lift enhancement, whose control effect is closely related to momentum coefficient and reduced frequency. With the increase of the reduced frequency, the control effect of the lift enhancement is slightly reduced. As the momentum coefficient increases, the control effect becomes better. When the angle of attack is greater than 4°, the increments of lift coefficients under the control of DSJ are larger than those under the control of the steady blowing at a same momentum coefficient. The maximum lift augmentation efficiency can reach 47 when the momentum coefficient is 0.02, which is higher than the value in the case with steady blowing jet circulation control.展开更多
Cationic hydrogels have received great attention to control eutrophication and recycle phosphate.In this study,a type of La(OH)_(3) loaded magnetic MAPTAC-based cationic hydrogel(La(OH)_(3)@MMCH)was developed as a pot...Cationic hydrogels have received great attention to control eutrophication and recycle phosphate.In this study,a type of La(OH)_(3) loaded magnetic MAPTAC-based cationic hydrogel(La(OH)_(3)@MMCH)was developed as a potential adsorbent for enhanced phosphate removal from aqueous environment.La(OH)_(3)@MMCH exhibited high adsorption capacity of 105.72±5.99 mg P/g,and reached equilibrium within 2 hr.La(OH)_(3)@MMCH could perform effectively in a wide pH range from 3.0 to 9.0 and in the presence of coexisting ions(including SO_(4)^(2-),Cl^(-),NO_(3)^(-),HCO_(3)^(-),SiO_(4)^(4-) and HA).The adsorption-desorption experiment indicated that La(OH)_(3)@MMCH could be easily regenerated by using NaOH-NaCl as the desorption agent,and 73.3%adsorption capacity remained after five cycles.Moreover,La(OH)_(3)@MMCH was employed to treat surface water with phosphate concentration of 1.90 mg/L and showed great removal efficiency of 95.21%.Actually,MMCH showed high surface charge density of 34.38-59.38 meq/kg in the pH range from 3.0 to 11.0 and great swelling ratio of 3014.57%within 24 h,indicating that MMCH could produce the enhanced Donnan membrane effect to pre-permeate phosphate.Furthermore,the bifunctional structure of La(OH)_(3)@MMCH enabled it to capture phosphate through electrostatic attraction and ligand exchange.All the results prove that La(OH)_(3)@MMCH is a promising adsorbent for eutrophication control and phosphate recovery.展开更多
To understand the displacement characteristics and remaining oil displacement process by the surfactant/polymer(SP) flooding in cores with different pore structures, the effects of pore structure on the enhanced oil r...To understand the displacement characteristics and remaining oil displacement process by the surfactant/polymer(SP) flooding in cores with different pore structures, the effects of pore structure on the enhanced oil recovery of SP flooding was investigated at the pore, core and field scales through conducting experiments on natural core samples with three typical types of pore structures. First, the in-situ nuclear magnetic resonance core flooding test was carried out to capture the remaining oil variation features in the water flooding and SP flooding through these three types of cores. Subsequently, at the core scale, displacement characteristics and performances of water flooding and SP flooding in these three types of cores were evaluated based on the full-size core flooding tests. Finally, at the field scale, production characteristics of SP flooding in the bimodal sandstone reservoir and multimodal conglomerate reservoir were compared using the actual field production data. The results show: as the pore structure gets more and more complex, the water flooding performance gets poorer, but the incremental recovery factor by SP flooding gets higher;the SP flooding can enhance the producing degree of oil in 1-3 μm pores in the unimodal and bimodal core samples, while it produces largely oil in medium and large pores more than 3 μm in pore radius in the multimodal core sample. The core flooding test using full-size core sample demonstrates that the injection of SP solution can significantly raise up the displacement pressure of the multimodal core sample, and greatly enhance recovery factor by emulsifying the remaining oil and enlarging swept volume. Compared with the sandstone reservoir, the multimodal conglomerate reservoir is more prone to channeling. With proper profile control treatments to efficiently enlarge the microscopic and macroscopic swept volumes, SP flooding in the conglomerate reservoir can contribute to lower water cuts and longer effective durations.展开更多
文摘Recently,an article was published on solid effect(SE)dynamic nuclear polarization(DNP)enhancement,where the au-thors reported achieving 1H enhancement factors up to 500 by increasing the microwave power at 9.4 T,marking the highest SE enhancement to date[1].
基金financially supported from the National Natural Science Foundation of China(No.52274358)the Natural Science Foundation of Hunan Province,China(No.2020JJ4718)+2 种基金the Major Science and Technology Projects of Gansu Province,China(No.22ZD6GC017)the Young Scientists Fund of National Natural Science Foundation of China(No.51404296)the National Key Research and Development Program of China(No.2018YFC1901604).
文摘Based on the properties of antimony(Sb)and arsenic(As),a method was proposed to enhance gold recovery during iron matte smelting.The impact of Sb and As on gold enhancement capture was investigated using an exclusion method.The results demonstrated that both Sb and As significantly improved the gold recovery rate.As the Sb or As content increased,the gold recovery rate increased.The enhancement effect of Sb was better than that of As,and the optimal results were achieved through the synergistic effects of Sb and As.Under optimized conditions,the gold recovery rate reached 97.12%,whereas the gold content in the slag decreased to 1.70 g/t.Sb captured and aggregated free gold as an Au-Sb alloy,whereas As-Fe alloy also captured free gold.The growth of the gold-captured phase size enhanced the settling velocity,thereby promoting gold recovery.
基金supported by the National Natural Science Foundation of China(Nos.U2468217,U2034205,and 52308391)。
文摘To elucidate the yielding performance of compact yielding anchor cables in working state,a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed.The yielding resistance enhancement effect(ω)caused by working environment constraints is evaluated through multi-layer composite sleeve hole expansion analysis,forming a theoretical framework for calculating the working yielding force.Laboratory and in-situ pull-out tests are conducted to determine the yielding performance and validate the analytical theory.The main conclusions are:(1)Yielding force and energy-release capacity increase withω,significantly outperforming the unconfined state.(2)In-situ tests under varying rockmass and geostress conditions(F1–F3)determine the yielding force increases to 183.4–290.1,204.0–290.8,and 235.0–327.1 kN.(3)The slight deviation(–12.5%to 6.2%)between the theoretical and measured yielding force confirms that the analytical theory effectively describes the working yielding performance.(4)ωincreases with higher geostress and improved rock mechanical properties,with initial geostress(σ_(0))and elastic modulus of surrounding rock(E_(3))identified as critical parameters.
基金Project(51008007)supported by the National Natural Science Foundation of ChinaProject(2013318J01100)supported by the Science and Technology Project of Ministry of Communications,China
文摘In the field of soil stabilization, only calcium silicate hydrate(CSH) and ettringite(AFt) as hydration products have been reported to directly contribute to the strength enhancement of the soil. A chloride dredger fill, an artificial chloride saline soil, and a non-saline soil were stabilized by Portland cement(PC) and PC with Ca(OH)_2(CH) with different contents. A series of unconfined compressive strength(UCS) tests of stabilized soil specimen after curing for 7 d and 28 d were carried out, and the hydration products and microstructure of the specimens were observed by X-ray diffractometry(XRD), scanning electronic microscopy(SEM), and energy-dispersive X-ray analysis(EDXA). The results showed that the strengths of PC+CH-stabilized chloride saline soils were much higher than those of PC-stabilized soils. A new hydration product of calcium aluminate chloride hydrate, also known as Friedel's salt, appeared in the PC+CH-stabilized chloride saline soils. The solid-phase volume of Friedel's salt expanded during the formation of the hydrate; this volume filled the pores in the stabilized soil. This pore-filling effect was the most important contribution to the significantly enhanced strength of the PC+CH-stabilized chloride saline soils. On the basis of this understanding, a new optimized stabilizer was designed according to the concept that the chloride in saline soil could be utilized as a component of the stabilizer. The strength of the chloride saline soils stabilized by the optimized stabilizer was even further increased compared with that of the PC+CH-stabilized soils.
文摘In this paper, modifications to the finite-difference time-domain(FD-TD) method for modeling microwave pulse coupling into a slot, which is much narrower than one conventional FD-TD cell, are discussed. The coupling process of microwave pulse into a slot is studied by using the modified FD-TD method, and the dependence of microwave coupling on slot sizes, the carrier frequencies and the polarization directions of the incident waves is analysed. Resonant and enhancement effects which occur in this process are observed. The condition at which the resonant effect takes place is also presented.
基金supported by the National Key Research and Development Program of China (No.2019YFA0708800)the Fundamental Research Funds for the Central Universities (No.DUT20ZD101)。
文摘Integral thin shells made of high strength aluminum alloys are urgently needed in new generation transportation equipment. There are challenges to overcoming the co-existing problems of wrinkling and splitting by the cold forming and hot forming processes. An innovative technology of ultra-low temperature forming has been invented for aluminum alloy thin shells by the new phenomenon of ‘dual enhancement effect’. That means plasticity and hardening are enhanced simultaneously at ultra-low temperatures. In this perspective, the dual enhancement effect is described, and the development, current state and prospects of this new forming method are introduced. This innovative method can provide a new approach for integral aluminum alloy components with large size, ultra-thin thickness, and high strength. An integral tank dome of rocket with 2 m in diameter was formed by using a blank sheet with the same thickness as the final component, breaking through the limit value of thickness-diameter ratio.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11834008,11704410,11632004,11474361,and U1930202).
文摘On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular tube,which is inherently induced by the closed propagation feature of CGWs.An appropriate mode pair of primary-and double-frequency CGWs satisfying the phase velocity matching and nonzero energy flux is selected to ensure that the second harmonic generated by primary CGW propagation can accumulate along the circumference.Using a coherent superposition of multi-waves,a model of unidirectional CGW propagation is established for analyzing the enhancement effect of cumulative SHG of primary CGW mode selected.The theoretical analyses and numerical simulations performed directly demonstrate that the second harmonic generated does have a cumulative effect along the circumferential direction and the closed propagation feature of CGWs does enhance the magnitude of cumulative second harmonic generated.Potential applications of the enhancement effect of cumulative SHG of CGWs are considered and discussed.The theoretical analysis and numerical simulation perspective presented here yield an insight previously unavailable into the physical mechanism of the enhancement effect of cumulative SHG by closed propagation feature of CGWs in a circular tube.
基金supported by the National Natural Science Foundation of China under Grant No. G050104011004024the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No. A0901040110018512026
文摘Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole approximation （DDA）,we study the absorption and scattering properties of two-dimensional square silver nanodisks （2D SSN） arrays on the single crystal silicon solar cell.Based on the effective reflective index model of the single crystal silicon solar cell,we investigate the optical enhancement absorption of light energy by varying the light incident direction,particle size,aspect ratio,and interparticle spacing of the silver nanodisks.The peak values and position of the optical extinction spectra of the 2D square arrays of noble metal nanodisks are obtained with the different array structures.
文摘Artificial fish nests are set in Lukou section and Hengyang section of Xiangjiang River from March 20 to May 10, 2019. The structure of artificial fish nest is bamboo frame, with the size of 2.5 m × 5.0 m × 4 and a unit frame area of 60 m<sup>2</sup>. A total of 58,201 eggs were collected by 24 monitoring times, of which 30,441 were from Lukou and 27,760 from Hengyang. 3831 fish eggs identify 8 fish species using morphological or molecular biological methods. The results showed that the number of eggs peaked from the 8<sup>th</sup> day to the 24<sup>th</sup> day after the nest entered the water, and then decreased rapidly. There was significant negative correlation between egg number in per m<sup>2</sup> fish nest and days of fish nest (P < 0.01). The economic benefits of artificial fish nests were RMB 11.81 million. The artificial fish nest can not only increase the population of fish, but also has significant economic benefits.
基金supported by National Natural Science Foundation of China(10574038)development project of high-tech industry of universities in Jiangsu(JHB05-08)Changzhou scientific and technological bureau(CE2005026).
文摘An orthogonal ultrasonic irradiation system consisting of HIFU with frequency at 1.05 MHz combined with ultrasound with frequency at 28 kHz was applied in this paper.Effect of cavitation was detected by pH-value measurement and conductance measurement.The result shows that the effect of cavitation caused by ultrasound with frequency at 28 kHz is greatly enhanced by HIFU piezoelectricity transducer with frequency at 1.05 MHz.
文摘The luminescent enhancement effect of Na_5Eu(MoO_4)_4 by doping(WO_4)^(2-) has been studied. When the value x in Na_5Eu(Mo_(1-x)W_xO_4)_4 is in 0<x<0.21,its photoluminescent spectrum is near to that of Na_5Eu(MoO_4)_4,but its luminescent intensity increases.When x=0.033,the intensity is increased by about 30%.According to the X-ray diffraction analysis,W ions get into the lattice and occupy the sites of the Mo ions.The change of crystal environment of Eu^(3+) may result in the luminescent enhancement.
基金This work was supported by the National Science Foundation of Hubei Province of China(No.2019CFB432)the National Natural Science Foundation of China(Nos.22076052 and 21976063)the China Postdoctoral Science Foundation(No.2018M642850).
文摘This study investigated the enhancement effects of dissolved carbonates on the peroxymonosulfate-based advanced oxidation process with CuS as a catalyst.It was found that the added CO_(3)^(2−)increased both the catalytic activity and the stability of the catalyst.Under optimized reaction conditions in the presence of CO_(3)^(2−),the degradation removal of 4-methylphenol(4-MP)within 2 min reached 100%,and this was maintained in consecutivemulti-cycle experiments.The degradation rate constant of 4-MP was 2.159 min^(−1),being 685%greater than that in the absence of CO_(3)^(2−)(0.315 min−1).The comparison of dominated active species and 4-MP degradation pathways in both CO_(3)^(2−)-free and CO_(3)^(2−)-containing systems suggested thatmore CO_(3)·^(−)/^(1)O_(2) was produced in the case of CO_(3)^(2−)deducing an electron transfer medium,which tending to react with electron-richmoieties.Meanwhile,Characterization by X-ray photoelectron spectroscopic and cyclic voltammetrymeasurement verified CO_(3)^(2−)enabled the effective reduction of Cu^(2+)to Cu^(+).By investigating the degradation of 11 phenolics with different substituents,the dependence of degradation kinetic rate constant of the phenolics on their chemical structures indicated that there was a good linear relationship between the Hammett constantsσp of the aromatic phenolics and the logarithm of k in the CO_(3)^(2−)-containing system.This work provides a new strategy for efficient removal of electron-rich moieties under the driving of carbonate being widely present in actual water bodies.
基金The Science and Technology Project of Guangdong Province under contract No.2019B121201001the National Key R&D Program of China under contract No.2019YFD0901301+3 种基金the Fund of China-Vietnam Joint Survey on Fish Stocks in the Common Fishing Zone of the Beibu Gulfthe Central Public-interest Scientific Institution Basal Research Fund,South China Sea Fisheries Research Institute,Chinese Academy of Fishery Science under contract No.2021SD14the China-ASEAN Maritime Cooperation Fund(China-Vietnam Fishery Stock Enhancement and Conservation in Beibu Gulf)the Hainan Provincial Natural Science Foundation of China under contract No.320QN358.
文摘The stock enhancement programs for black sea bream Acanthopagrus schlegelii have been conducted in China for a fewyears.However,little information has been reported concerning the effectiveness and genetic effect of black sea bream stock enhancement.In order to detect the contribution of released individuals in Zhujiang River Estuary(ZRE)and Daya Bay(DB),six microsatellite markers were used to identify the hatchery-released individuals.In addition,this pedigree of hatchery populations(broodfish and hatchery-released offspring)was traced to detect the number of effective parents(N_(e)),the inbreeding coefficient and the decrease of genetic variability in the reproduction.The pedigree reconstruction showed that at least 69(out of 93)broodfish had offspring.The estimated N_(e) was 54.8,consequently the inbreeding coefficient was 0.91%.The genetic diversity of hatchery-released offspring was lower than that in that of broodfish(heterozygosity alleles,0.727-0.774),some alleles(number of alleles,61-69)and genetic variance were lost during reproduction.It was observed that wild samples had higher levels of genetic diversity compared with hatchery populations as well as recaptured samples in releasing area.A total of 128 hatchery-released black sea bream were identified among 487 recaptured samples in ZRE,while a total of 15 samples were identified among 96 samples in DB.In summary,there was a high survival of released fish.N_(e)vertheless,the results provided evidence to consider a loss of genetic variation in hatcheryreleased stock and a negative genetic effect of the stock enhancement.
基金M.Xiang and S.Dong wishes to thank the National Natural Science Foundation of China(21908086 and 51801083)Changzhou Sci&Tech Program(CJ20190035)+1 种基金Jiangsu Higher Education Institutions in China(19KJB610011)Natural Science Foundation of Jiangsu Province(BK20181044).
文摘Influenced by recent COVID-19,wearing face masks to block the spread of the epidemic has become the simplest and most effective way.However,after the people wear masks,thousands of tons of medical waste by used dis-posable masks will be generated every day in the world,causing great pressure on the environment.Herein,con-ductive polymer composites are fabricated by simple melt blending of mask fragments(mask polypropylene,short for mPP)and multi-walled carbon nanotubes(MWNTs).MWNTs were used as modifiers for composites because of their high strength and high conductivity.The crystalline structure,mechanical,electrical and thermal enhancement effect of the composites were investigated.MWNTs with high thermal stability acted the role of promoting the crystallisation of mPP by expediting the crystalline nucleation,leading to the improvement of amount for crystalline nucleus.MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network.With 2.0 wt% MWNTs loading,the tensile strength and electrical conductivity of the composites were increased by 809% and 7 orders of magnitude.MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network.Thus,more conducting paths were constructed to transport carriers.The findings may open a way for high value utilization of the disposable masks.
基金supported by the National Key R&D Program of China (Grant Nos.2023YFA1406002 and 2020YFA0308801)the National Natural Science Foundation of China (NSFC) (Grant Nos.12321004,12174025,12074041,and 12204045)+7 种基金the CAS Superconducting Research Project (Grant No.SCZX-0101)the Fundamental Research Funds for the Central Universities (Grant No.2243300003)the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0302800)supported by the Synergetic Extreme Condition User Facility (SECUF)Analysis & Testing center in Beijing Institute of Technologysupport from the Beijing Institute of Technology Research Fund Program (Grant No.2023CX01027)support from the Beijing Institute of Technology Research Fund Program for Young Scholarssupport from the Beijing Institute of Technology Laboratory Research Project (Grant No.2023BITSYB07)。
文摘The kagome ferrimagnet TbMn_(6)Sn_(6),featuring a pristine Mn kagome lattice,has emerged as a candidate Chern magnet with a large intrinsic anomalous Hall effect(AHE).While chemical substitution can modulate its properties,hydrostatic pressure provides a disorder-free route to manipulate electronic and magnetic interactions.Herein,we investigate the effects of hydrostatic pressure on electrical and magneto-transport in TbMn6Sn6 up to 18.3 GPa.Pressure significantly enhances hysteresis in the magnetoresistance and Hall responses,causing a concurrent monotonic coercive field increase,suggesting the enhancement of interlayer magnetic couplings in a robust c-axis ferrimagnetic order.The intrinsic anomalous Hall conductivity increases considerably from 129.5 S·cm^(−1) at ambient pressure conditions to 448.7 S·cm^(−1) at 14.0 GPa—an enhancement of 247%that is unprecedented among pressure-tuned kagome magnets.Based on density functional theory calculations,we reveal that pressure induces multiple gap openings near the Fermi level,giving rise to pronounced Berry curvature hotspots that may contribute to the AHE.Our results show that pressure can be used to enhance the intrinsic topological responses of this kagome magnet.
文摘The dominant property of building envelope fabric which contributes significantly to minimize electricity utilization in building is the thermo-physical properties. There is inadequate literature on representative practical data of thermo-physical properties of the dominant building envelope components in Ghana. This study aims to use cost-effective approach to characterize the thermo-physical properties of only cement-based mortar and concrete blocks used in Ghana for building components specifically wall design. Mixed methods research design was employed to achieving the aim. A questionnaire survey was used among sampled building fabric components manufacturers to pick representative data on thermos-physical properties of their mortar and concrete blocks. Also, an experimental procedure employing a transient technique with a TCi Thermal Analyser was used to determine the thermo-physical properties of selected mortar and concrete blocks from Ghana in addition to designed parametric mortar and concrete blocks with varied ratios obtained from the survey were undertaken at University of Nottingham. From the study, a trend of decreasing thermal conductivity and thermal effusivity with corresponding decreasing sand content was observed with all the different sand types. The thermal conductivities of both mortar and concrete parametric blocks meet the range of expected standard values outlined in Chattered Institute of Building Services Engineers (CIBSE) Guide A. The major limitation of the work is the dimension of the sample size;which is not inconsistent with standard block size due to the experimental setup used. It is expected that, the characterization of the predominant cement-based building fabrics components will contribute to improved building performance analysis with significant savings in electricity utilization for space cooling.
基金supported by the National Natural Science Foundation of China(21673030)the Fundamental Research Funds for the Central Universities(DUT16QY49)
文摘In terms of the reaction of COreduction to CO with hydrogen, COconversion is very low at low temperature due to the limitation of thermodynamic equilibrium（TE）. To overcome this limitation, plasma catalytic reduction of COto CO in a catalyst-filled dielectric barrier discharge（DBD） reactor is studied. An enhanced effect of plasma on the reaction over Au/CeOcatalysts is observed. For both the conventionally catalytic（CC） and plasma catalytic（PC, Pin= 15 W） reactions under conditions of 400 °C, H/CO= 1,200 SCCM, GHSV = 12,000 mL·gcat·h, COconversions over Au/CeOreach 15.4% and 25.5% due to the presence of Au, respectively, however, those over CeOare extremely low and negligible. Moreover,COconversion over Au/CeOin the PC reaction exceeds 22.4% of the TE conversion. Surface intermediate species formed on the catalyst samples during the reactions are determined by in-situ temperatureprogrammed decomposition（TPD） technique. Interestingly, it disclosed that in the PC reaction, the formation of formate intermediate is enhanced by plasma, and the acceleration by plasma in the decomposition of formate species is much greater than that in the formation of formate species on Au/CeO. Enhancement factor is introduced to quantify the enhanced effect of plasma. Lower reactor temperature, higher gas hourly space velocity（GHSV）, and lower molar ratio of H/COwould be associated with larger enhancement factor.
基金co-supported by the National Natural Science Foundation of China(Nos.11972369 and 11872374)the Youth Science and Technology Innovation Award funded project of National University of Defense Technology,China(434517314).
文摘The Dual Synthetic Jet Actuator(DSJA) is used to develop a new type of lift enhancement device based on circulation control, and to control the flow over the two-dimensional(2D)NACA0015 airfoil. The lift enhancement device is composed of a DSJA and a rounded trailing edge(Coanda surface). The two outlets of the DSJA eject two jets(Jet 1 and Jet 2). Jet 1 ejects from the upper trailing edge, which increases the circulation of airfoil with the help of the Coanda surface. Jet2 ejects from the lower trailing edge, which acts as a virtual flap. The Reynolds number based on the airfoil chord length and free flow velocity is 250000. The results indicate that the circulation control method based on Dual Synthetic Jet(DSJ) has good performance in lift enhancement, whose control effect is closely related to momentum coefficient and reduced frequency. With the increase of the reduced frequency, the control effect of the lift enhancement is slightly reduced. As the momentum coefficient increases, the control effect becomes better. When the angle of attack is greater than 4°, the increments of lift coefficients under the control of DSJ are larger than those under the control of the steady blowing at a same momentum coefficient. The maximum lift augmentation efficiency can reach 47 when the momentum coefficient is 0.02, which is higher than the value in the case with steady blowing jet circulation control.
基金This work was supported by the Beijing Municipal Science and Technology Project(No.Z181100005518007)the National Key Research and Development Program of China(No.2017YFC0505303)the National Natural Science Foundation of China(Nos.51978054 and 51678053).
文摘Cationic hydrogels have received great attention to control eutrophication and recycle phosphate.In this study,a type of La(OH)_(3) loaded magnetic MAPTAC-based cationic hydrogel(La(OH)_(3)@MMCH)was developed as a potential adsorbent for enhanced phosphate removal from aqueous environment.La(OH)_(3)@MMCH exhibited high adsorption capacity of 105.72±5.99 mg P/g,and reached equilibrium within 2 hr.La(OH)_(3)@MMCH could perform effectively in a wide pH range from 3.0 to 9.0 and in the presence of coexisting ions(including SO_(4)^(2-),Cl^(-),NO_(3)^(-),HCO_(3)^(-),SiO_(4)^(4-) and HA).The adsorption-desorption experiment indicated that La(OH)_(3)@MMCH could be easily regenerated by using NaOH-NaCl as the desorption agent,and 73.3%adsorption capacity remained after five cycles.Moreover,La(OH)_(3)@MMCH was employed to treat surface water with phosphate concentration of 1.90 mg/L and showed great removal efficiency of 95.21%.Actually,MMCH showed high surface charge density of 34.38-59.38 meq/kg in the pH range from 3.0 to 11.0 and great swelling ratio of 3014.57%within 24 h,indicating that MMCH could produce the enhanced Donnan membrane effect to pre-permeate phosphate.Furthermore,the bifunctional structure of La(OH)_(3)@MMCH enabled it to capture phosphate through electrostatic attraction and ligand exchange.All the results prove that La(OH)_(3)@MMCH is a promising adsorbent for eutrophication control and phosphate recovery.
基金Supported by China National Science and Technology Major Project(2016ZX05025-003-010) and (2016ZX05010-005).
文摘To understand the displacement characteristics and remaining oil displacement process by the surfactant/polymer(SP) flooding in cores with different pore structures, the effects of pore structure on the enhanced oil recovery of SP flooding was investigated at the pore, core and field scales through conducting experiments on natural core samples with three typical types of pore structures. First, the in-situ nuclear magnetic resonance core flooding test was carried out to capture the remaining oil variation features in the water flooding and SP flooding through these three types of cores. Subsequently, at the core scale, displacement characteristics and performances of water flooding and SP flooding in these three types of cores were evaluated based on the full-size core flooding tests. Finally, at the field scale, production characteristics of SP flooding in the bimodal sandstone reservoir and multimodal conglomerate reservoir were compared using the actual field production data. The results show: as the pore structure gets more and more complex, the water flooding performance gets poorer, but the incremental recovery factor by SP flooding gets higher;the SP flooding can enhance the producing degree of oil in 1-3 μm pores in the unimodal and bimodal core samples, while it produces largely oil in medium and large pores more than 3 μm in pore radius in the multimodal core sample. The core flooding test using full-size core sample demonstrates that the injection of SP solution can significantly raise up the displacement pressure of the multimodal core sample, and greatly enhance recovery factor by emulsifying the remaining oil and enlarging swept volume. Compared with the sandstone reservoir, the multimodal conglomerate reservoir is more prone to channeling. With proper profile control treatments to efficiently enlarge the microscopic and macroscopic swept volumes, SP flooding in the conglomerate reservoir can contribute to lower water cuts and longer effective durations.
