Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machin...Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machining.Noxious slurries are widely used in conventional chemical mechanical polishing(CMP),resulting in the possible pollution to the environment.Moreover,the traditional slurries normally contain more than four ingredients,causing difficulties to control the process and quality of CMP.To solve these challenges,a novel green CMP for single crystal diamond was developed,consisting of only hydrogen peroxide,diamond abrasive and Prussian blue(PB)/titania catalyst.After CMP,atomic surface is achieved with surface roughness Sa of 0.079 nm,and the MRR is 1168 nm·h^(-1).Thickness of damaged layer is merely 0.66 nm confirmed by transmission electron microscopy(TEM).X-ray photoelectron spectroscopy,electron paramagnetic resonance and TEM reveal that·OH radicals form under ultraviolet irradiation on PB/titania catalyst.The·OH radicals oxidize diamond,transforming it from monocrystalline to amorphous atomic structure,generating a soft amorphous layer.This contributes the high MRR and formation of atomic surface on diamond.The developed novel green CMP offers new insights to achieve atomic surface of diamond for potential use in their high-performance devices.展开更多
An innovative approach based on water environmental capacity for non-point source NPS pollution removal rate estimation was discussed by using both univariate and multivariate data analysis.Taking Shenzhen city as the...An innovative approach based on water environmental capacity for non-point source NPS pollution removal rate estimation was discussed by using both univariate and multivariate data analysis.Taking Shenzhen city as the study case a 67% to 74% NPS pollutant load removal rate can lead to meeting the chemical oxygen demand COD pollution control target for most watersheds.In contrast it is hardly to achieve the ammonia nitrogen NH4-N total phosphorus TP and biological oxygen demand BOD5 pollution control target by simply removing NPS pollutants. This highlights that the pollution control strategies should be taken according to different pollutant species and sources in different watersheds rather than one-size-fits-all .展开更多
The stress intensity factors and stress conditions of machining cracks are analyzed by fracture mechanics on the basis of honing characteristics and of brittle ceramic mechanical behavior.Because the honing incidental...The stress intensity factors and stress conditions of machining cracks are analyzed by fracture mechanics on the basis of honing characteristics and of brittle ceramic mechanical behavior.Because the honing incidental tensile stresses effectively decrease the critical grinding stresses and increase the stress intensity factors of machining cracks,the honing process can be carried out easily.The results show that honing can be an efficient machining method for brittle materials.展开更多
In order to enhance the hydraulic loading rate （HLR） of a subsurface wastewater infiltration system （SWIS） used in treating domestic sewage, the intermittent operation mode was employed in the SWIS. The results sh...In order to enhance the hydraulic loading rate （HLR） of a subsurface wastewater infiltration system （SWIS） used in treating domestic sewage, the intermittent operation mode was employed in the SWIS. The results show that the intermittent operation mode contributes to the improvement of the HLR and the pollutant removal rate. When the wetting-drying ratio （RwD） was 1.0, the pollutant removal rate increased by （13.6 ± 0.3）% for NH3-N, （20.7 ± 1.1）% for TN, （18.6± 0.4）% for TP, （12.2 ± 0.5）% for BOD, （10.1 ± 0.3）% for COD, and （36.2 ± 1.2）% for SS, compared with pollutant removal rates under the continuous operation mode. The pollutant removal rate declined with the increase of the HLR. The effluent quality met The Reuse of Urban Recycling Water - Water Quality Standard for Scenic Environment Use （GB/T 18921-2002） even when the HLR was as high as 10 cm/d. Hydraulic conductivity, oxidation reduction potential （ORP）, the quantity of nitrifying bacteria, and the pollutant removal rate of NH3-N increased with the decrease of the RWD. For the pollutant removal rates of TP, BOD, and COD, there were no significant difference （p 〈 0.05） under different RwDS. The suggested RWD was 1.0. Relative contribution of the pretreatment and SWlS to the pollutant removal was examined, and more than 80% removal of NH3-N, TN, TP, COD, and BOD occurred in the SWIS.展开更多
Ce^(3+)as the active site on the CeO_(2)abrasive surface is the key to enhancing the material removal rate(MRR).The CeO_(2)abrasives with high chemical activity were prepared by the molten salt method under a reducing...Ce^(3+)as the active site on the CeO_(2)abrasive surface is the key to enhancing the material removal rate(MRR).The CeO_(2)abrasives with high chemical activity were prepared by the molten salt method under a reducing atmosphere.The crystal structure and morphology of CeO_(2)abrasive s were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR),ultraviolet—visible diffuse reflectance spectroscopy(UV-Vis DRS),and X-ray photoelectron spectroscopy(XPS).The CeO_(2)abrasives were obtained under different atmospheres(Air,Ar,and Ar/H_(2)).With the enhancement of the reducing atmosphere,the morphology of the abrasives transforms from spherical to octahedral,while more oxygen vacancies and Ce^(3+)are generated on the surface of CeO_(2)abrasives.The CMP experiments show that the MRRs of the CeO_(2)-Air,CeO_(2)-Ar,and CeO_(2)-Ar/H_(2)abrasives on SiO_(2)substrates are 337.60,578.74,and 691.28 nm/min,respectively.Moreover,as confirmed by atomic force microscopy(AFM),the substrate surfaces exhibit low roughness(20.5 nm)after being polished using all of the prepared samples.Especially,the MRR of CeO_(2)-Ar/H_(2)abrasives is increased by 104.76%compared with CeO_(2)-air abrasives.The improved CMP performance is attributed to the increased Ce^(3+)concentration and the octahedral morphology of the abrasives enhancing the chemical reaction and mechanical removal at the abrasive-substrate interface.展开更多
In the present study,a novel method of surface finish improvement is proposed using shot blasting of soda lime(SBSL)beads on the Mg-AZ31 alloy.The effect of the soda blasting process parameters,such as blast pressure,...In the present study,a novel method of surface finish improvement is proposed using shot blasting of soda lime(SBSL)beads on the Mg-AZ31 alloy.The effect of the soda blasting process parameters,such as blast pressure,stand-off distance,and blast duration,have been studied in-response of material removal rate(MRR)and surface roughness(SR)and corresponding statistical models have been obtained.The multi-objective optimization has also been performed to obtain parameters for maximum MRR and minimum SR.The corrosion behavior of the treated specimens has been performed to study their in-vitro biodegradability in simulated body fluid(SBF)for 1,3,7,10,15,and 21 days.The wettability study of the SBSL treated samples has been investigated using sessile drop methodology.Further,cell adhesion test has also been performed to study the biocompatibility characteristics of the SBSL treated samples using Huh7 liver cell lines.Based on obtained quantitative data as well as scanning electron microscopy analysis of treated samples,the SBSL treatment of the AZ31 alloy has been found highly useful in producing biocompatibility surfaces along with desirable morphological features.展开更多
A computational fluid dynamic （ CFD ） analysis of air movement and aerosol particle transport in a two-zone ventilated room with an inter-zonal opening is presented to study the impact of ventilation strategies and ...A computational fluid dynamic （ CFD ） analysis of air movement and aerosol particle transport in a two-zone ventilated room with an inter-zonal opening is presented to study the impact of ventilation strategies and size of the opening on indoor particle dispersion and concentration distribution. The comparisons of average particle concentrations in both zones between the computations and the experiments from the literature are generally satisfactory and acceptable. The combined effects of sizes of the opening and the inlet and outlet locations （three different strategies） are simulated and discussed. The results show that ventilation strategy and size of the opening influence the particle removal rate in zone 1. The removal rate is decreased when the air supply system is changed from the tap-inlet to the bottom-inlet configuration. The top-inlet system obtains a better particle deposition in zone I than the bottom-inlet configuration. However, the particle concentration at breathing level is lower for bottomsupply system than for top-supply. Decreasing the size of interzonal opening increases the particle deposition rate in zone 1 only for the top.supply system, especially for coarse particles.展开更多
The mechanical characters of CdZnTe crystal were investigated by nanoscratch tests, and the effects of mechanical anisotropy on the material removal rate and surface quality were studied by polishing tests. There is a...The mechanical characters of CdZnTe crystal were investigated by nanoscratch tests, and the effects of mechanical anisotropy on the material removal rate and surface quality were studied by polishing tests. There is a peak of frictional coefficient at the early stage of scratch, and increasing the vertical force will result in the increase of peak value correspondingly. The fluctuation phenomenon of frictional coefficient is generated at high vertical force. The lateral forces show the apparent twofold and threefold symmetries on （110） and （111） planes, respectively. To obtain high surface quality, low polishing pressure and hard direction （〈 T10 〉 directions on （110） plane and 〈 112 〉 directions on （111） plane） should be selected, and to achieve high material removal rate, high polishing pressure and soft direction （〈001〉 directions on （110） plane and 〈 121 〉 directions on （111） plane） should be selected.展开更多
[ Objective] The study aimed to discuss the removal rate of phosphorus by different constructed wetland substrates. [ Methed] Based on static experiments, we analyzed the removal rate and characteristics of phosphorus...[ Objective] The study aimed to discuss the removal rate of phosphorus by different constructed wetland substrates. [ Methed] Based on static experiments, we analyzed the removal rate and characteristics of phosphorus by different constructed wetland substrates like steel slag, cin- der slag, shale, boiler slag, soil and gravel. [ Result~ The maximum adsorption of phosphorus by various substrates showed as follows, steel slag 〉 cinder slag 〉 shale 〉 boiler slag 〉 soil 〉 gravel. When the initial concentration of phosphorus was 5 mg/L, the removal rate of phosphorus by the steel slag, cinder slag, shale, boiler slag, soil and gravel was 99.76%, 85.8%, 71.2%, 63.0%, 46.8% and 11.7% respectively. It is suggested that shale and boiler slag can be used as the substrate of subsurface-flow constructed wetlands; cinder slag can be chosen as a renewable sub- strate for intensifying phosphorus removal; steel slag could be used at the end of subsurface-flow constructed wetlands for treating TP in outflows. [Concluslon] The research could provide theoretical references for choosing a suitable substrate for constructed wetlands to remove phosphorus in future.展开更多
Nitrous oxide（N_2O） is a potent greenhouse gas that can be emitted during biological nitrogen removal. N_2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600 m L/min sequenc...Nitrous oxide（N_2O） is a potent greenhouse gas that can be emitted during biological nitrogen removal. N_2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600 m L/min sequencing batch reactor（SBRL） and 1200 m L/min（SBRH）.The nitrogen removal percentage was 89% in SBRLand 71% in SBRH, respectively. N_2O emission mainly occurred during the aerobic phase, and the N_2O emission factor was 10.1%in SBRLand 2.3% in SBRH, respectively. In all batch experiments, the N_2O emission potential was high in SBRLcompared with SBRH. In SBRL, with increasing aeration rates, the N_2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification（SND）. By contrast, in SBRHthe N_2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N_2O emission during biological nitrogen removal.展开更多
[Objectives]To provide a theoretical basis for constructing the best species suitable for local shrimp-bivalves-algae IMTA through the screening of different bivalves and the determination of seaweed density.[Methods]...[Objectives]To provide a theoretical basis for constructing the best species suitable for local shrimp-bivalves-algae IMTA through the screening of different bivalves and the determination of seaweed density.[Methods]The preliminary studies of different kind of bivalves and macroalgae(Gracilaria lichevoides)used for the purification of shrimp effluent were described.Through the screening of benthic bivalves,the best ratio of integrated culture of bivalves and algae was determined.[Results]Both bivalves and macroalgae had certain purification effects on aquaculture wastewater,but the effects significantly differed from species and breeding density.The removal rate of nutrient declined from Potamocorbula laevis,Sinonovacula constricta,Tegillarca granosa.The mixotrophic culture of 8 ind/L P.laevis and 120 g G.lichevoides had the highest efficiency of purification and removal rates of nutrient:NH4-N:90.67%,TP:86.18%,TN:72.66%,NO3-N:51.85%,respectively.There was a significant difference between the blank control group and the other three groups(P<0.01).The 8 ind/L+120 g group was significantly higher than the 4 ind/L+120 g group(P<0.05)in TP removal rate.Additionally,the difference between four groups was significant in the removal rate of NH4-N and TN(P<0.05),but 2 ind/L+120 g group and 8 ind/L+120 g group in the removal rate of NO3-N had no significant difference(P>0.05).[Conclusions]This research provides a reference for the use of filterable shellfish and large seaweed to treat aquaculture wastewater,and also provides the theoretical basis for constructing the local multi-level breeding structure.展开更多
This article presents an Artificial Neural Network （ANN） architecture to model the Electrical Discharge Machining （EDM） process. It is aimed to develop the ANN model using an input-output pattern of raw data colle...This article presents an Artificial Neural Network （ANN） architecture to model the Electrical Discharge Machining （EDM） process. It is aimed to develop the ANN model using an input-output pattern of raw data collected from an experimental of EDM process, whereas several research objectives have been outlined such as experimenting machining material for selected gap current, identifying machining parameters for ANN variables and selecting appropriate size of data selection. The experimental data （input variables） of copper-electrode and steel-workpiece is based on a selected gap current where pulse on time, pulse off time and sparking frequency have been chosen at optimum value of Material Removal Rate （MRR）. In this paper, the result has significantly demonstrated that the ANN model is capable of predicting the MRR with low percentage prediction error when compared with the experimental result.展开更多
As a non-contact ultra-precision machining method,abrasive water jet polishing(AWJP)has signi-ficant application in optical elements processing due to its stable tool influence function(TIF),no subsurface damage and s...As a non-contact ultra-precision machining method,abrasive water jet polishing(AWJP)has signi-ficant application in optical elements processing due to its stable tool influence function(TIF),no subsurface damage and strong adaptability to workpiece shapes.In this study,the effects of jet pressure,nozzle diameter and impinging angle on the distribution of pressure,velocity and wall shear stress in the polishing flow field were systematically analyzed by computational fluid dynamics(CFD)simulation.Based on the Box-Behnken experimental design,a response surface regression model was constructed to investigate the influence mech-anism of process parameters on material removal rate(MRR)and surface roughness(Ra)of fused silica.And experimental results showed that increasing jet pressure and nozzle diameter significantly improved MRR,consistent with shear stress distribution revealed by CFD simulations.However,increasing jet pressure and impinging angle caused higher Ra values,which was unfavorable for surface quality improvement.Genetic algorithm(GA)was used for multi-objective optimization to establish Pareto solutions,achieving concurrent optimization of polishing efficiency and surface quality.A parameter combination of 2 MPa jet pressure,0.3 mm nozzle diameter,and 30°impinging angle achieved MRR of 169.05μm^(3)/s and Ra of 0.50 nm.Exper-imental verification showed prediction errors of 4.4%(MRR)and 3.8%(Ra),confirming the model’s reliabil-ity.This parameter optimization system provides theoretical basis and technical support for ultra-precision polishing of complex curved optical components.展开更多
Applied Immobilized algae bacteria (ABI) to remove ammonia of freshwater aquaculture wastewater. Temperature (T),PH,light intensity (I),dissolved oxygen (DO) and filling rate five factors plays important role in the p...Applied Immobilized algae bacteria (ABI) to remove ammonia of freshwater aquaculture wastewater. Temperature (T),PH,light intensity (I),dissolved oxygen (DO) and filling rate five factors plays important role in the process of ammonia nitrogen removal ,related data between ammonia removal and five factors was received through multi-factor orthogonal test,and established relations model between the five factor and nitrogen removal. The results show that five-factors had significant effect on AR,and the best combinations for removing AR was temperature 30 ℃,pH=7.0,light intensity 6 000 lux,dissolved oxygen 5.0 mg/L and the fill rate 10%. According to the experimental data,equation model was proposed and coefficient of determination R2 =0.864 8,P<0.05. Samples T-test was done between the model predictions and the actual measured values.Test results showed that the significant difference of overall mean value sig. (2-tailed) was 0.978 (P>0.05),it Shows that had no significant difference between model predictions and the actual measured value,and model had a high degree of fitting.展开更多
Chemical leaching techniques have been proven effective in removing heavymetal contaminants fromsoil using various leaching agents.Previous research has shown that both singleagent and composite leaching systems have ...Chemical leaching techniques have been proven effective in removing heavymetal contaminants fromsoil using various leaching agents.Previous research has shown that both singleagent and composite leaching systems have been applied for the remediation of chromiumcontaminated soils,with varying degrees of success depending on soil type and contaminant form.However,the removal rate of total chromium(Cr)and hexavalent chromium(Cr(Ⅵ))often fluctuates based on the chemical composition of the leaching agents,as well as the soil’s physicochemical properties,such as pH and Cr speciation stability.Therefore,this study investigates the effectiveness of 20 composite leaching systems,including deionized water,lime water,calcium chloride,sodium carbonate,and sodium phosphate,through soil column leaching tests.The aim was to evaluate their impact on soil pH,total Cr,and Cr(Ⅵ)removal,and to examine the transformation of various Cr species during the leaching process.Results reveal that lime water and sodium phosphate were particularly effective in stabilizing Cr(Ⅵ)and neutralizing soil pH,while total Cr removal amount ranged from 197.4 mg/kg to 1671.6 mg/kg and Cr(Ⅵ)removal amount ranged from 113.2mg/kg to 316.8mg/kg.We also find that using 0.2 mol/L citric acid,0.1 mol/L hydrochloric acid,and 1.2 mL/g lime solution adjusted soil pH to 7.37,with average removal efficiencies of 34.6%.for total Cr and 72.7%for Cr(Ⅵ).Overall,our results suggest that the combined use of lime water and sodium phosphate is an effective strategy for remediating chromium-contaminated soil,particularly for stabilizing unleached Cr and adjusting soil pH.展开更多
Flow-electrode capacitive deionization(FCDI)is a newly developed desalination technology with a high electrode loading for superior salt removal efficiency,even with high feed salinity.However,the improvement in FCDI ...Flow-electrode capacitive deionization(FCDI)is a newly developed desalination technology with a high electrode loading for superior salt removal efficiency,even with high feed salinity.However,the improvement in FCDI performance could be restricted by obstacles such as poor charge transfer in the electrode slurry and agglomeration of the electrode particles.Therefore,various FCDIelectrode materials have been studied to overcome these bottlenecks through various mechanisms.Herein,a minireview is conducted to summarize the relevant information and provide a comprehensive view of the progress in FCDI electrode materials.Flow-electrode materials can be classified into three main groups:carbon materials,metalbased materials,and carbon-metal composites.Carbonbased capacitive materials with outstanding conductivities can facilitate charge transfer in FCDI,whereas metal-based materials and carbon-metal composites with ion-intercalative behaviors exhibit high ion adsorption abilities.Additionally,carbon materials with surface function groups can enhance electrode dispersion and reach a high electrode loading by electrostatic repulsion,further upgrading the conductive network of FCDI.Moreover,magnetic carbon-metal composites can be easily separated,and the salt removal performance can be improved with magnetic fields.Different electrode materials exhibit disparate features during FCDI development.Thus,combining these materials to obtain FCDI electrodes with multiple functions may be reasonable,which could be a promising direction for FCDI research.展开更多
For the treatment of the mixed flue gas desulfurization wastewater with high salinity by the biological fluidized bed process,the optimum temperature was 25-35℃,and the optimum hydraulic retention time was 10 h.When ...For the treatment of the mixed flue gas desulfurization wastewater with high salinity by the biological fluidized bed process,the optimum temperature was 25-35℃,and the optimum hydraulic retention time was 10 h.When the influent quality was stable,the average concentration of COD,NH_(4)^(+)-N and TN in the inlet water was 210,11 and 16.3 mg/L,respectively,and their average concentration in the effluent was 54,0.32 and 4.09 mg/L,respectively.The treatment effect was good.When the incoming water quality of flue gas desulfurization wastewater fluctuated greatly,the effluent quality was still relatively stable after being treated by the biological fluidized bed,indicating that the biological fluidized bed process had a good ability to resist the impact of water quality in the treatment of high-salinity flue gas desulfurization wastewater.At the same time,the biological fluidized bed process provides a reference for high-salinity wastewater that is difficult to be biologically treated.展开更多
Methacrylic acid was used together with a molecular imprinting technique to modify chitosan. In addition, the adsorption kinetics and adsorption isotherms were recorded and the results were analyzed to investigate rep...Methacrylic acid was used together with a molecular imprinting technique to modify chitosan. In addition, the adsorption kinetics and adsorption isotherms were recorded and the results were analyzed to investigate reparative adsorption for Cr（VI） from the polluted Xiangjiang River water. A comparative X-ray analysis shows that the degree of crystallization in the imprinted polymer was significantly weakened, the area of the non-crystalline region was larger. There were more adsorption sites in the imprinted polymer, and the adsorption capacity towards Cr（VI） was increased. The adsorption capacity of the imprinted polymer towards Cr（VI） increased with time and reaches saturation after 8 h. The optimal adsorption time was 4-8 h after the adsorption starting and the optimal pH value for the solution was in the range of 4.5-7.5. When the chitosan reaches saturation, the adsorption capacity achieves a state of equilibrium, and the maximum Cr（VI） extraction rate reaches 33.7%. Moreover, the adsorption capacity of the imprinted polymer towards Cr（VI） increases with increasing chitosan concentration. In this situation, the Cr（VI） extraction rate shows little variation, and the maximum removal rate can reach 98.3%. Furthermore, the Cr（VI） extraction rate increases with an increase in the degree of deacetylation in the chatoyant and chitosan, with the best adsorption effect corresponding to 90% deacetylation. Fitting the adsorption data to the quasi first- and second-order kinetic models yields correlation coefficients of 0.9013 and 0.9875, respectively. The corresponding rate constants for the two models are 0.0091 min-1 and 7.129 g/（mg.min）, respectively. Hence, the adsorption using Cr（VI）-imprinted chitosan is more consistent with the second-order kinetics. Comparing the data to Freundlich and Langrnuir adsorption isotherms shows that the latter has a better linear fit and a maximum adsorption capacity of 15.784 mg/g.展开更多
Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were ...Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The results show that the effects of roasting temperature and holding time on the removal rate of F and Cl are the most significant, and the effect of stirring speed is the second. The defluorination rate reaches 92.6% while the dechlorination rate reaches 90.2%, under the process conditions of roasting temperature of 700 °C, holding time of 80 min and stirring speed of 120 r/min. The results indicate that the removal of F and Cl from fuming furnace production of zinc oxide fumes using microwave roasting process is feasible and reliable.展开更多
Considering the self-excited and forced vibrations in high-speed milling processes, a novel method for dynamic optimization of system stability is used to determine the cutting parameters and structural parameters by ...Considering the self-excited and forced vibrations in high-speed milling processes, a novel method for dynamic optimization of system stability is used to determine the cutting parameters and structural parameters by increasing the chatter free material removal rate （CF-MRR） and surface finish. The method is hased on the theory of the chatter stability and the semi-bandwidth of the resonant region. The objective function of the method is material removal rate（MRR）,the constraints are chatter stability and surface finish, and the optimizing variables are cutting and structural parameters. The optimization procedure is stated. The method is applied to a milling system and CF-MRR is increased 18.86%. It is shown that the influences of the chatter stability and the resonance are simultaneously considered in the dynamic optimization of the milling system for increasing CF-MRR and the surface finish.展开更多
基金financial support from the National Key Research and Development Program of China(2018YFA0703400)the Fundamental Research Funds for the Provincial Universities of Zhejiang(GK239909299001021)+1 种基金the Ninth China Association for Science and Technology Youth Talent Lift Project Support Plan(KYZ015324002)the Changjiang Scholars Program of Chinese Ministry of Education。
文摘Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machining.Noxious slurries are widely used in conventional chemical mechanical polishing(CMP),resulting in the possible pollution to the environment.Moreover,the traditional slurries normally contain more than four ingredients,causing difficulties to control the process and quality of CMP.To solve these challenges,a novel green CMP for single crystal diamond was developed,consisting of only hydrogen peroxide,diamond abrasive and Prussian blue(PB)/titania catalyst.After CMP,atomic surface is achieved with surface roughness Sa of 0.079 nm,and the MRR is 1168 nm·h^(-1).Thickness of damaged layer is merely 0.66 nm confirmed by transmission electron microscopy(TEM).X-ray photoelectron spectroscopy,electron paramagnetic resonance and TEM reveal that·OH radicals form under ultraviolet irradiation on PB/titania catalyst.The·OH radicals oxidize diamond,transforming it from monocrystalline to amorphous atomic structure,generating a soft amorphous layer.This contributes the high MRR and formation of atomic surface on diamond.The developed novel green CMP offers new insights to achieve atomic surface of diamond for potential use in their high-performance devices.
基金The National Science and Technology Major Project of China(No.2012ZX07301-001)the Shenzhen Environmental Research Project,China Postdoctoral Science Foundation(No.2013M530642)
文摘An innovative approach based on water environmental capacity for non-point source NPS pollution removal rate estimation was discussed by using both univariate and multivariate data analysis.Taking Shenzhen city as the study case a 67% to 74% NPS pollutant load removal rate can lead to meeting the chemical oxygen demand COD pollution control target for most watersheds.In contrast it is hardly to achieve the ammonia nitrogen NH4-N total phosphorus TP and biological oxygen demand BOD5 pollution control target by simply removing NPS pollutants. This highlights that the pollution control strategies should be taken according to different pollutant species and sources in different watersheds rather than one-size-fits-all .
文摘The stress intensity factors and stress conditions of machining cracks are analyzed by fracture mechanics on the basis of honing characteristics and of brittle ceramic mechanical behavior.Because the honing incidental tensile stresses effectively decrease the critical grinding stresses and increase the stress intensity factors of machining cracks,the honing process can be carried out easily.The results show that honing can be an efficient machining method for brittle materials.
基金supported by the National Natural Science Foundation of China(Grant No.51108275)the Program for Liaoning Excellent Talents in Universities(LNET)(Grant No.LJQ2012101)+2 种基金the Program for New Century Excellent Talents in Universities(Grant No.NCET-11-1012)the Science and Technology Program of Liaoning Province(Grants No.2011229002 and2013229012)the Basic Science Research Fund in Northeastern University(Grants No.N130501001 and N140105003)
文摘In order to enhance the hydraulic loading rate （HLR） of a subsurface wastewater infiltration system （SWIS） used in treating domestic sewage, the intermittent operation mode was employed in the SWIS. The results show that the intermittent operation mode contributes to the improvement of the HLR and the pollutant removal rate. When the wetting-drying ratio （RwD） was 1.0, the pollutant removal rate increased by （13.6 ± 0.3）% for NH3-N, （20.7 ± 1.1）% for TN, （18.6± 0.4）% for TP, （12.2 ± 0.5）% for BOD, （10.1 ± 0.3）% for COD, and （36.2 ± 1.2）% for SS, compared with pollutant removal rates under the continuous operation mode. The pollutant removal rate declined with the increase of the HLR. The effluent quality met The Reuse of Urban Recycling Water - Water Quality Standard for Scenic Environment Use （GB/T 18921-2002） even when the HLR was as high as 10 cm/d. Hydraulic conductivity, oxidation reduction potential （ORP）, the quantity of nitrifying bacteria, and the pollutant removal rate of NH3-N increased with the decrease of the RWD. For the pollutant removal rates of TP, BOD, and COD, there were no significant difference （p 〈 0.05） under different RwDS. The suggested RWD was 1.0. Relative contribution of the pretreatment and SWlS to the pollutant removal was examined, and more than 80% removal of NH3-N, TN, TP, COD, and BOD occurred in the SWIS.
基金the National Natural Science Foundation of China(51905324)the Scientific Research Program Funded by Shaanxi Provincial Education Department(20JK0545)the Doctoral Scientific Research Startup Foundation of Shaanxi University of Science and Technology(2018BJ-14)。
文摘Ce^(3+)as the active site on the CeO_(2)abrasive surface is the key to enhancing the material removal rate(MRR).The CeO_(2)abrasives with high chemical activity were prepared by the molten salt method under a reducing atmosphere.The crystal structure and morphology of CeO_(2)abrasive s were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR),ultraviolet—visible diffuse reflectance spectroscopy(UV-Vis DRS),and X-ray photoelectron spectroscopy(XPS).The CeO_(2)abrasives were obtained under different atmospheres(Air,Ar,and Ar/H_(2)).With the enhancement of the reducing atmosphere,the morphology of the abrasives transforms from spherical to octahedral,while more oxygen vacancies and Ce^(3+)are generated on the surface of CeO_(2)abrasives.The CMP experiments show that the MRRs of the CeO_(2)-Air,CeO_(2)-Ar,and CeO_(2)-Ar/H_(2)abrasives on SiO_(2)substrates are 337.60,578.74,and 691.28 nm/min,respectively.Moreover,as confirmed by atomic force microscopy(AFM),the substrate surfaces exhibit low roughness(20.5 nm)after being polished using all of the prepared samples.Especially,the MRR of CeO_(2)-Ar/H_(2)abrasives is increased by 104.76%compared with CeO_(2)-air abrasives.The improved CMP performance is attributed to the increased Ce^(3+)concentration and the octahedral morphology of the abrasives enhancing the chemical reaction and mechanical removal at the abrasive-substrate interface.
文摘In the present study,a novel method of surface finish improvement is proposed using shot blasting of soda lime(SBSL)beads on the Mg-AZ31 alloy.The effect of the soda blasting process parameters,such as blast pressure,stand-off distance,and blast duration,have been studied in-response of material removal rate(MRR)and surface roughness(SR)and corresponding statistical models have been obtained.The multi-objective optimization has also been performed to obtain parameters for maximum MRR and minimum SR.The corrosion behavior of the treated specimens has been performed to study their in-vitro biodegradability in simulated body fluid(SBF)for 1,3,7,10,15,and 21 days.The wettability study of the SBSL treated samples has been investigated using sessile drop methodology.Further,cell adhesion test has also been performed to study the biocompatibility characteristics of the SBSL treated samples using Huh7 liver cell lines.Based on obtained quantitative data as well as scanning electron microscopy analysis of treated samples,the SBSL treatment of the AZ31 alloy has been found highly useful in producing biocompatibility surfaces along with desirable morphological features.
基金National Natural Science Foundation of China (No.40975012)
文摘A computational fluid dynamic （ CFD ） analysis of air movement and aerosol particle transport in a two-zone ventilated room with an inter-zonal opening is presented to study the impact of ventilation strategies and size of the opening on indoor particle dispersion and concentration distribution. The comparisons of average particle concentrations in both zones between the computations and the experiments from the literature are generally satisfactory and acceptable. The combined effects of sizes of the opening and the inlet and outlet locations （three different strategies） are simulated and discussed. The results show that ventilation strategy and size of the opening influence the particle removal rate in zone 1. The removal rate is decreased when the air supply system is changed from the tap-inlet to the bottom-inlet configuration. The top-inlet system obtains a better particle deposition in zone I than the bottom-inlet configuration. However, the particle concentration at breathing level is lower for bottomsupply system than for top-supply. Decreasing the size of interzonal opening increases the particle deposition rate in zone 1 only for the top.supply system, especially for coarse particles.
基金supported by the Key Project of the National Natural Science Foundation of China (No. 50535020)the Fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University (No. SKLSP200902)
文摘The mechanical characters of CdZnTe crystal were investigated by nanoscratch tests, and the effects of mechanical anisotropy on the material removal rate and surface quality were studied by polishing tests. There is a peak of frictional coefficient at the early stage of scratch, and increasing the vertical force will result in the increase of peak value correspondingly. The fluctuation phenomenon of frictional coefficient is generated at high vertical force. The lateral forces show the apparent twofold and threefold symmetries on （110） and （111） planes, respectively. To obtain high surface quality, low polishing pressure and hard direction （〈 T10 〉 directions on （110） plane and 〈 112 〉 directions on （111） plane） should be selected, and to achieve high material removal rate, high polishing pressure and soft direction （〈001〉 directions on （110） plane and 〈 121 〉 directions on （111） plane） should be selected.
基金Supported by National Natural Science Foundation of China(50278016)
文摘[ Objective] The study aimed to discuss the removal rate of phosphorus by different constructed wetland substrates. [ Methed] Based on static experiments, we analyzed the removal rate and characteristics of phosphorus by different constructed wetland substrates like steel slag, cin- der slag, shale, boiler slag, soil and gravel. [ Result~ The maximum adsorption of phosphorus by various substrates showed as follows, steel slag 〉 cinder slag 〉 shale 〉 boiler slag 〉 soil 〉 gravel. When the initial concentration of phosphorus was 5 mg/L, the removal rate of phosphorus by the steel slag, cinder slag, shale, boiler slag, soil and gravel was 99.76%, 85.8%, 71.2%, 63.0%, 46.8% and 11.7% respectively. It is suggested that shale and boiler slag can be used as the substrate of subsurface-flow constructed wetlands; cinder slag can be chosen as a renewable sub- strate for intensifying phosphorus removal; steel slag could be used at the end of subsurface-flow constructed wetlands for treating TP in outflows. [Concluslon] The research could provide theoretical references for choosing a suitable substrate for constructed wetlands to remove phosphorus in future.
基金supported by the Shenzhen Overseas High-Level Talents Innovation Funds Peacock Plan Project (No. KQCX20120814155347053)the National Natural Science Foundation of China (No. 51108242)
文摘Nitrous oxide（N_2O） is a potent greenhouse gas that can be emitted during biological nitrogen removal. N_2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600 m L/min sequencing batch reactor（SBRL） and 1200 m L/min（SBRH）.The nitrogen removal percentage was 89% in SBRLand 71% in SBRH, respectively. N_2O emission mainly occurred during the aerobic phase, and the N_2O emission factor was 10.1%in SBRLand 2.3% in SBRH, respectively. In all batch experiments, the N_2O emission potential was high in SBRLcompared with SBRH. In SBRL, with increasing aeration rates, the N_2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification（SND）. By contrast, in SBRHthe N_2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N_2O emission during biological nitrogen removal.
基金Ningbo Science and Technology Project of Enriching the People in 2015(2015C10008)Ningbo Science and Technology Plan Project(2019C10039)+1 种基金Zhejiang Science and Technology Plan Project(2019C02054)Special Project for the Construction of Modern Agricultural Industrial Technology System(CARS-49).
文摘[Objectives]To provide a theoretical basis for constructing the best species suitable for local shrimp-bivalves-algae IMTA through the screening of different bivalves and the determination of seaweed density.[Methods]The preliminary studies of different kind of bivalves and macroalgae(Gracilaria lichevoides)used for the purification of shrimp effluent were described.Through the screening of benthic bivalves,the best ratio of integrated culture of bivalves and algae was determined.[Results]Both bivalves and macroalgae had certain purification effects on aquaculture wastewater,but the effects significantly differed from species and breeding density.The removal rate of nutrient declined from Potamocorbula laevis,Sinonovacula constricta,Tegillarca granosa.The mixotrophic culture of 8 ind/L P.laevis and 120 g G.lichevoides had the highest efficiency of purification and removal rates of nutrient:NH4-N:90.67%,TP:86.18%,TN:72.66%,NO3-N:51.85%,respectively.There was a significant difference between the blank control group and the other three groups(P<0.01).The 8 ind/L+120 g group was significantly higher than the 4 ind/L+120 g group(P<0.05)in TP removal rate.Additionally,the difference between four groups was significant in the removal rate of NH4-N and TN(P<0.05),but 2 ind/L+120 g group and 8 ind/L+120 g group in the removal rate of NO3-N had no significant difference(P>0.05).[Conclusions]This research provides a reference for the use of filterable shellfish and large seaweed to treat aquaculture wastewater,and also provides the theoretical basis for constructing the local multi-level breeding structure.
文摘This article presents an Artificial Neural Network （ANN） architecture to model the Electrical Discharge Machining （EDM） process. It is aimed to develop the ANN model using an input-output pattern of raw data collected from an experimental of EDM process, whereas several research objectives have been outlined such as experimenting machining material for selected gap current, identifying machining parameters for ANN variables and selecting appropriate size of data selection. The experimental data （input variables） of copper-electrode and steel-workpiece is based on a selected gap current where pulse on time, pulse off time and sparking frequency have been chosen at optimum value of Material Removal Rate （MRR）. In this paper, the result has significantly demonstrated that the ANN model is capable of predicting the MRR with low percentage prediction error when compared with the experimental result.
文摘As a non-contact ultra-precision machining method,abrasive water jet polishing(AWJP)has signi-ficant application in optical elements processing due to its stable tool influence function(TIF),no subsurface damage and strong adaptability to workpiece shapes.In this study,the effects of jet pressure,nozzle diameter and impinging angle on the distribution of pressure,velocity and wall shear stress in the polishing flow field were systematically analyzed by computational fluid dynamics(CFD)simulation.Based on the Box-Behnken experimental design,a response surface regression model was constructed to investigate the influence mech-anism of process parameters on material removal rate(MRR)and surface roughness(Ra)of fused silica.And experimental results showed that increasing jet pressure and nozzle diameter significantly improved MRR,consistent with shear stress distribution revealed by CFD simulations.However,increasing jet pressure and impinging angle caused higher Ra values,which was unfavorable for surface quality improvement.Genetic algorithm(GA)was used for multi-objective optimization to establish Pareto solutions,achieving concurrent optimization of polishing efficiency and surface quality.A parameter combination of 2 MPa jet pressure,0.3 mm nozzle diameter,and 30°impinging angle achieved MRR of 169.05μm^(3)/s and Ra of 0.50 nm.Exper-imental verification showed prediction errors of 4.4%(MRR)and 3.8%(Ra),confirming the model’s reliabil-ity.This parameter optimization system provides theoretical basis and technical support for ultra-precision polishing of complex curved optical components.
基金Supported by the National Natural Science Foundation of China(No.30972260)~~
文摘Applied Immobilized algae bacteria (ABI) to remove ammonia of freshwater aquaculture wastewater. Temperature (T),PH,light intensity (I),dissolved oxygen (DO) and filling rate five factors plays important role in the process of ammonia nitrogen removal ,related data between ammonia removal and five factors was received through multi-factor orthogonal test,and established relations model between the five factor and nitrogen removal. The results show that five-factors had significant effect on AR,and the best combinations for removing AR was temperature 30 ℃,pH=7.0,light intensity 6 000 lux,dissolved oxygen 5.0 mg/L and the fill rate 10%. According to the experimental data,equation model was proposed and coefficient of determination R2 =0.864 8,P<0.05. Samples T-test was done between the model predictions and the actual measured values.Test results showed that the significant difference of overall mean value sig. (2-tailed) was 0.978 (P>0.05),it Shows that had no significant difference between model predictions and the actual measured value,and model had a high degree of fitting.
基金supported by the National Key Research and Development Program of China(No.2023YFC3707902)China Postdoctoral Science Foundation(No.2024M752168)+1 种基金Jiangsu Funding Programfor Excellent Postdoctoral Talent(No.2024ZB393)the National Natural Science Foundation of China(No.42407126).
文摘Chemical leaching techniques have been proven effective in removing heavymetal contaminants fromsoil using various leaching agents.Previous research has shown that both singleagent and composite leaching systems have been applied for the remediation of chromiumcontaminated soils,with varying degrees of success depending on soil type and contaminant form.However,the removal rate of total chromium(Cr)and hexavalent chromium(Cr(Ⅵ))often fluctuates based on the chemical composition of the leaching agents,as well as the soil’s physicochemical properties,such as pH and Cr speciation stability.Therefore,this study investigates the effectiveness of 20 composite leaching systems,including deionized water,lime water,calcium chloride,sodium carbonate,and sodium phosphate,through soil column leaching tests.The aim was to evaluate their impact on soil pH,total Cr,and Cr(Ⅵ)removal,and to examine the transformation of various Cr species during the leaching process.Results reveal that lime water and sodium phosphate were particularly effective in stabilizing Cr(Ⅵ)and neutralizing soil pH,while total Cr removal amount ranged from 197.4 mg/kg to 1671.6 mg/kg and Cr(Ⅵ)removal amount ranged from 113.2mg/kg to 316.8mg/kg.We also find that using 0.2 mol/L citric acid,0.1 mol/L hydrochloric acid,and 1.2 mL/g lime solution adjusted soil pH to 7.37,with average removal efficiencies of 34.6%.for total Cr and 72.7%for Cr(Ⅵ).Overall,our results suggest that the combined use of lime water and sodium phosphate is an effective strategy for remediating chromium-contaminated soil,particularly for stabilizing unleached Cr and adjusting soil pH.
基金financially supported by the National Natural Science Foundation of China(No.52374423)the Science and Technology Innovation Program of Hunan Province(No.2021RC4010)the Science and Technology Major Project of Changsha(No.kh2401030)
文摘Flow-electrode capacitive deionization(FCDI)is a newly developed desalination technology with a high electrode loading for superior salt removal efficiency,even with high feed salinity.However,the improvement in FCDI performance could be restricted by obstacles such as poor charge transfer in the electrode slurry and agglomeration of the electrode particles.Therefore,various FCDIelectrode materials have been studied to overcome these bottlenecks through various mechanisms.Herein,a minireview is conducted to summarize the relevant information and provide a comprehensive view of the progress in FCDI electrode materials.Flow-electrode materials can be classified into three main groups:carbon materials,metalbased materials,and carbon-metal composites.Carbonbased capacitive materials with outstanding conductivities can facilitate charge transfer in FCDI,whereas metal-based materials and carbon-metal composites with ion-intercalative behaviors exhibit high ion adsorption abilities.Additionally,carbon materials with surface function groups can enhance electrode dispersion and reach a high electrode loading by electrostatic repulsion,further upgrading the conductive network of FCDI.Moreover,magnetic carbon-metal composites can be easily separated,and the salt removal performance can be improved with magnetic fields.Different electrode materials exhibit disparate features during FCDI development.Thus,combining these materials to obtain FCDI electrodes with multiple functions may be reasonable,which could be a promising direction for FCDI research.
文摘For the treatment of the mixed flue gas desulfurization wastewater with high salinity by the biological fluidized bed process,the optimum temperature was 25-35℃,and the optimum hydraulic retention time was 10 h.When the influent quality was stable,the average concentration of COD,NH_(4)^(+)-N and TN in the inlet water was 210,11 and 16.3 mg/L,respectively,and their average concentration in the effluent was 54,0.32 and 4.09 mg/L,respectively.The treatment effect was good.When the incoming water quality of flue gas desulfurization wastewater fluctuated greatly,the effluent quality was still relatively stable after being treated by the biological fluidized bed,indicating that the biological fluidized bed process had a good ability to resist the impact of water quality in the treatment of high-salinity flue gas desulfurization wastewater.At the same time,the biological fluidized bed process provides a reference for high-salinity wastewater that is difficult to be biologically treated.
基金Project(41271332)supported by the National Natural Science Foundation of ChinaProject(2010YBB186)supported by the Social Science Foundation of Hunan Province,Chian
文摘Methacrylic acid was used together with a molecular imprinting technique to modify chitosan. In addition, the adsorption kinetics and adsorption isotherms were recorded and the results were analyzed to investigate reparative adsorption for Cr（VI） from the polluted Xiangjiang River water. A comparative X-ray analysis shows that the degree of crystallization in the imprinted polymer was significantly weakened, the area of the non-crystalline region was larger. There were more adsorption sites in the imprinted polymer, and the adsorption capacity towards Cr（VI） was increased. The adsorption capacity of the imprinted polymer towards Cr（VI） increased with time and reaches saturation after 8 h. The optimal adsorption time was 4-8 h after the adsorption starting and the optimal pH value for the solution was in the range of 4.5-7.5. When the chitosan reaches saturation, the adsorption capacity achieves a state of equilibrium, and the maximum Cr（VI） extraction rate reaches 33.7%. Moreover, the adsorption capacity of the imprinted polymer towards Cr（VI） increases with increasing chitosan concentration. In this situation, the Cr（VI） extraction rate shows little variation, and the maximum removal rate can reach 98.3%. Furthermore, the Cr（VI） extraction rate increases with an increase in the degree of deacetylation in the chatoyant and chitosan, with the best adsorption effect corresponding to 90% deacetylation. Fitting the adsorption data to the quasi first- and second-order kinetic models yields correlation coefficients of 0.9013 and 0.9875, respectively. The corresponding rate constants for the two models are 0.0091 min-1 and 7.129 g/（mg.min）, respectively. Hence, the adsorption using Cr（VI）-imprinted chitosan is more consistent with the second-order kinetics. Comparing the data to Freundlich and Langrnuir adsorption isotherms shows that the latter has a better linear fit and a maximum adsorption capacity of 15.784 mg/g.
基金Project(51104073)supported by the National Natural Science Foundation of ChinaProject(2013AA064003)supported by the High-tech Research and Development Program of China+1 种基金Project(2014CB643404)supported by the National Basic Research Program of ChinaProject(2012HB008)supported by Yunnan Province Young Academic Technology Leader Reserve Talents,China
文摘Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The results show that the effects of roasting temperature and holding time on the removal rate of F and Cl are the most significant, and the effect of stirring speed is the second. The defluorination rate reaches 92.6% while the dechlorination rate reaches 90.2%, under the process conditions of roasting temperature of 700 °C, holding time of 80 min and stirring speed of 120 r/min. The results indicate that the removal of F and Cl from fuming furnace production of zinc oxide fumes using microwave roasting process is feasible and reliable.
基金Supported by the National Key Basic Research Program of China("973"Project)(2009CB724401)the China Postdoctoral Science Foundation(20070420208)the Postdoctoral Innovation Foundation of Shandong Province(200702023)~~
文摘Considering the self-excited and forced vibrations in high-speed milling processes, a novel method for dynamic optimization of system stability is used to determine the cutting parameters and structural parameters by increasing the chatter free material removal rate （CF-MRR） and surface finish. The method is hased on the theory of the chatter stability and the semi-bandwidth of the resonant region. The objective function of the method is material removal rate（MRR）,the constraints are chatter stability and surface finish, and the optimizing variables are cutting and structural parameters. The optimization procedure is stated. The method is applied to a milling system and CF-MRR is increased 18.86%. It is shown that the influences of the chatter stability and the resonance are simultaneously considered in the dynamic optimization of the milling system for increasing CF-MRR and the surface finish.
