Ce-ZrO2 is a widely used three-way catalyst support. Because of the large surface area and excellent redox quality, Ce-ZrO2 may have potential application in selective catalytic reduction （SCR） systems. In the prese...Ce-ZrO2 is a widely used three-way catalyst support. Because of the large surface area and excellent redox quality, Ce-ZrO2 may have potential application in selective catalytic reduction （SCR） systems. In the present work, Ce-ZrO2 was introduced into a low-temperature SCR system and CeO2 and ZrO2 supports were also introduced to make a contrastive study. Mn/CeO2, Mn/ZrO2 and Mn/Ce-ZrO2 were prepared by impregnating these supports with Mn（NO3）2 solution, and have been characterized by N2-BET, XRD, TPR, TPD, XPS, FT-IR and TG. The activity and resistance to SO2 and H2O of the catalysts were investigated. Mn/Ce-ZrO2 and Mn/CeO2 were proved to have better low-temperature activities than Mn/ZrO2, and yielded 98.6% and 96.8% NO conversion at 180℃, respectively. This is mainly because Mn/Ce-ZrO2 and Mn/CeO2 had higher dispersion of manganese oxides, better redox properties and more weakly adsorbed oxygen species than Mn/ZrO2. In addition, Mn/Ce-ZrO2 showed a good resistance to SO2 and H2O and presented 87.1% NO conversion, even under SO2 and H2O treatment for 6 hours, and the activity of Mn/Ce-ZrO2 was almost restored to its original level after cutting off the injection of SO2 and H2O. This was due to the weak water absorption and weak sulfation process on the surface of the catalyst.展开更多
Objective： To determine the value of diffusion-tensor imaging （DTI） as an adjunct to dynamic contrastenhanced magnetic resonance imaging （DCE-MRI） for improved accuracy of differential diagnosis between breast du...Objective： To determine the value of diffusion-tensor imaging （DTI） as an adjunct to dynamic contrastenhanced magnetic resonance imaging （DCE-MRI） for improved accuracy of differential diagnosis between breast ductal carcinoma in situ （DCIS） and invasive breast carcinoma （IBC）. Methods： The MRI data of 63 patients pathologically confirmed as breast cancer were analyzed. The conventional MRI analysis metrics included enhancement style, initial enhancement characteristic, maximum slope of increase, time to peak, time signal intensity curve （TIC） pattern, and signal intensity on FS- T2WI. The values of apparent diffusion coefficient （ADC）, directionally-averaged mean diffusivity （D^vg）, exponential attenuation （EA）, fractional anisotropy （FA）, volume ratio （VR） and relative anisotropy （RA） were calculated and compared between DCIS and IBC. Multivariate logistic regression was used to identify independent factors for distinguishing IBC and DCIS. The diagnostic performance of the diagnosis equation was evaluated using the receiver operating characteristic （ROC） curve. The diagnostic efficacies of DCE- MRI, DWI and DTI were compared independently or combined. Results： EA value, lesion enhancement style and TIC pattern were identified as independent factor for differential diagnosis of IBC and DCIS. The combination diagnosis showed higher diagnostic efficacy than a single use of DCE-MRI （P=0.02）, and the area of the curve was improved from 0.84 （95% CI, 0.67-0.99） to 0.94 （95% CI, 0.85-1.00）. Conclusions： Quantitative DTI measurement as an adjunct to DCE-MRI could improve the diagnostic performance of differential diagnosis between DCIS and IBC compared to a single use of DCE-MRI.展开更多
Gd^3+/TiO_(2)and Gd_(2)O_(3)/TiO_(2)nanoparticles were prepared by ball milling method.The effects of Gd^3+ion and Gd2O3 on the structure and optical property of TiO2 were studied by XRD and UV-vis DRS.Specific surfac...Gd^3+/TiO_(2)and Gd_(2)O_(3)/TiO_(2)nanoparticles were prepared by ball milling method.The effects of Gd^3+ion and Gd2O3 on the structure and optical property of TiO2 were studied by XRD and UV-vis DRS.Specific surface area was determined by Brunauer-Emmett-Teller(BET)method.The morphology and elemental composition were characterized by SEM-EDS.XPS was used to determine the surface compositions and chemical character of elements.The sample sizes and microstructures were observed by TEM.The photocatalytic activities of TiO2 nanoparticles modified with rare earth metal gadolinium(Gd^3+ion or Gd_(2)O_(3))were evaluated by degradation of methylene blue(MB)under UV light.Experimental results indicate that 2,5 mol%Gd^3+/TiO2 shows the best photocatalytic activity compared with Gd2O3/TiO2 and pure TiO2.The existence of gadolinium can exhibit the aggregation and induce lattice distortion of TiO2 obtained from XRD,SEM and TEM results.The band gap energy of 2.5 mol%Gd^3+/TiO2 decreases to3.07 eV and it leads to visible light absorption response which can be seen from UV-vis absorption spectra.The surface area of 2.5 mol%Gd^3+/TiO2 equals to 85.8 m^2/g and average crystal size is 21.1 nm.EDS and XPS analyses reveal that gadolinium can be introduced either into TiO2 lattice or adsorbed on the surface of TiO2.The content of surface OH groups in 2.5 mol%Gd^3+/TiO2 is 50,88%(1.55 times higher than that of pure TiO2)and the content of lattice oxygen decreases to 11.26%.The MB(25 mg/L)degradation reaction rate constants of 2,5 mol%Gd^3+/TiO2,0.5 mol%Gd2O3/TiO2 and pure TiO2 were0.0713,0.0588 and 0.0263 min^-1,respectively.The degradation rates of rhodamine B(30 mg/L)in 60 min are 97,9%,90.1%and 84.6%for 2,5 mol%Gd^3+/TiO2,0.5 mol%Gd2O3/TiO2 and pure TiO2,respectively.展开更多
Membrane separation has become an important technology to deal with the global water crisis. The polymerbased membrane technology is currently in the forefront of water purification and desalination but is plagued wit...Membrane separation has become an important technology to deal with the global water crisis. The polymerbased membrane technology is currently in the forefront of water purification and desalination but is plagued with some bottlenecks. Laminated graphene oxide(GO) membranes exhibit excellent advantages in water purification and desalination due to the single atomic layer structure, hydrophilic property, rich oxygen-containing groups for modification, mechanical and chemical robust, anti-fouling properties, facile and large-scale production, etc. Thus the GO-based membrane technology is believed to offer huge opportunities for efficient and practical water treatment. This review systematically summarizes the current progress on the water flux and selectivity intensification, stability improvement, anti-fouling and anti-biofouling ability enhancement by structural control and modification. To improve the performance of the laminated GO membrane, interlayer spacing tunability and surface modification are mainly used to enhance its water flux and selectivity. It is found that the stability and biofouling also block the service life of the GO membrane. The crosslinking method is found to effectively solve the stability of GO membrane in aqueous environment. Introducing nanoparticles is a widely used method to improve the membrane biofouling ability. Overall, we believe that this review could provide benefit to researchers in the area of GO-based membrane technology for water treatment.展开更多
Ball milling method was applied to prepare Lu^3＋/TiO2 photocatalysts. The catalysts were characterized with X-ray powder diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, UV-visible diffuse reflectance spe...Ball milling method was applied to prepare Lu^3＋/TiO2 photocatalysts. The catalysts were characterized with X-ray powder diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, UV-visible diffuse reflectance spectra（UV-vis DRS）, energy dispersive X-ray spectrometer（EDS）, transmission electron microscopy（TEM） and Brunauer-Emmett-Teller（BET） method. The photocatalytic activities were determined by the degradation of methylene blue（MB） equipped with a 300 W medium pressure mercury lamp. Results show that the first order reaction rate constants of Lu^3＋/TiO2 and pure TiO2 are0.0565 and 0.0263 min-1, respectively, which both were evaluated under the condition of catalysts loading of 0.2 g/L,initial concentration of 25 mg/L for MB, mole ratio of Lu^3＋/TiO2 of 1.5% and milling time of 4 h. The average crystal sizes of 1.5 mol% Lu^3＋/TiO2 and pure TiO2 are 18.7 and 19.3 nm, respectively.展开更多
Design and application of tunable phononic crystals(PnCs)are attracting increasing interest due to their promising capabilities to manipulate acoustic and elastic waves effectively.This paper investigates topology opt...Design and application of tunable phononic crystals(PnCs)are attracting increasing interest due to their promising capabilities to manipulate acoustic and elastic waves effectively.This paper investigates topology optimization of the magnetorheological(MR)materials including PnCs for opening the tunable and wide bandgaps.Therein,the bandgap tunability of the PnCs is achieved by shear modulus variation of MR materials under a continuously changing applied magnetic field.The pseudo elemental densities representing the bi-material distribution inside the PnC unit cell are taken as design variables and interpolated with an artificial MR penalization model.An aggregated bandgap index for enveloping the extreme values ofbandgap width and tunable range of the MR included smart PnCs is proposed as the objective function.In this context,the sensitivity analysis scheme is derived,and the optimization problem is solved with the gradient-based mathematical programming method.The effectiveness of the proposed optimization method is demonstrated by numerical examples,where the optimized solutions present tunable and stably wide bandgap characteristics under different magnetic fields.The tunable optimized PnCs based device that can provide a wider tunable bandgap range is also explored.展开更多
Catalytic oxidation of Hgo to Hg~O is an efficient way to remove Hg^(0) from coal-fired flue gas.The catalyst with ordered pore structure can lower mass transfer resistance resulting in higher Hg^(0) oxidation efficie...Catalytic oxidation of Hgo to Hg~O is an efficient way to remove Hg^(0) from coal-fired flue gas.The catalyst with ordered pore structure can lower mass transfer resistance resulting in higher Hg^(0) oxidation efficiency.Therefore,in the present work,wood vessels were used as sacrificial template to obtain Co_(3)O_(4) with ordered pore structure.SEM and BET results show that,when the mass concentrations of Co(NO_(3))_(2)·6H_(2)O was 20%,the obtained catalyst(Co_(3)O_(4) [20%Co(NO_(3))_(2)])possesses better pore structure and higher surface area.It will expose more available surface active sites and lower the mass transfer resistance.Furthermore,XPS results prove that Co_(3)O_(4) [20%Co(NO_(3))_(2)]has the highest ratio of chemisorbed oxygen which plays an important role in Hg^(0) oxidation process.These results lead to a better Hg^(0) oxidation efficiency of Co_(3)O_(4) [20%Co(NO_(3))_(2)],which is about 90%in the temperature range of 200 to 350℃,Furthermore,Co_(3)O_(4) [20%Co(NO_(3))_(2)]has a stable catalytic activity,and its Hg^(0) oxidation efficiency maintains above 90%at 250℃even after 90 h test,A probable reaction mechanism is deduced by the XPS results of the fresh,used and regenerated catalyst of Co_(3)O_(4) [20%Co(NO3)2].Chemisorbed oxygen can react with Hg^(0) forming HgO with the reduction of Co^(3+)to Co^(2)+.And lattice oxygen and gaseous oxygen can supplement the consumption of chemisorbed oxygen to oxidize Co^(2+)to Co^(3+).展开更多
An efficient and profitable separation process was proposed to prepare 5N （the purity of the metal solution reaches 99.999%） high-purity nickel from 3N nickel-solutions using Purolite S984. The adsorption performanc...An efficient and profitable separation process was proposed to prepare 5N （the purity of the metal solution reaches 99.999%） high-purity nickel from 3N nickel-solutions using Purolite S984. The adsorption performance of this superior resin, especially its selectivity for metal ions, was explored quantitatively. The maximum adsorption capacity for copper was 2.286 mmol/g calculated by the Langmuir model, which was twice as large as that for nickel. In the binary systems, the adsorption capacity for nickel was decreased by 45%, indicating direct competition for the active sites. The infinite separation factor for copper versus nickel exceeded 300, revealing the feasibility of preparing 5N-level high-purity nickel solutions, which was further verified using the 800 BV （bed volume） effluent in the column dynamic process. According to the cost-benefit analysis, purification contributed to a profit of approximately 60,000 USD per cycle, and the investment return period was less than 1/3 years. Density functional theory analysis confirmed that four nitrogen atoms would be involved in the coordination complex and thus a structure involving two five-membered rings could be achieved. The X-ray photoelectron spectra confirmed the involvement of nitrogen atoms, implying a coordination ratio of approximately 1：1.展开更多
Dear Editor,Vesicovaginal fistula(VVF)is an abnormal opening between the urinary bladder and the vagina.The condition has an immense psychological effect on patients due to the continuous leakage of urine or watery va...Dear Editor,Vesicovaginal fistula(VVF)is an abnormal opening between the urinary bladder and the vagina.The condition has an immense psychological effect on patients due to the continuous leakage of urine or watery vaginal discharge.The wet feeling and foul smell associated with leakage of urine cause social outcasting of the patients.This leads to immense emotional trauma and makes life miserable for the patient.The most common etiology for VVF in developing countries is obstructed labour[1],and in developed countries,it is abdominal hysterectomy[2].VVF poses a challenging problem to the surgeon.The location and the size of the fistula determine the extent of the patients’symptoms.展开更多
Realistic modelling and interactive rendering of forestry and landscape is a challenge in computer graphics and virtual reality.Recent new developments in plant growth modelling and simulation lead to plant models fai...Realistic modelling and interactive rendering of forestry and landscape is a challenge in computer graphics and virtual reality.Recent new developments in plant growth modelling and simulation lead to plant models faithful to botanical structure and development,not only representing the complex architecture of a real plant but also its functioning in interaction with its environment.Complex geometry and material of a large group of plants is a big burden even for high performances computers,and they often overwhelm the numerical calculation power and graphic rendering power.Thus,in order to accelerate the rendering speed of a group of plants,software techniques are often developed.In this paper,we focus on plant organs,i.e.leaves,flowers,fruits and inter-nodes.Our approach is a simplification process of all sparse organs at the same time,i.e.,Level of Detail(LOD),and multi-resolution models for plants.We do explain here the principle and construction of plant simplification.They are used to construct LOD and multi-resolution models of sparse organs and branches of big trees.These approaches take benefit from basic knowledge of plant architecture,clustering tree organs according to biological structures.We illustrate the potential of our approach on several big virtual plants for geometrical compression or LOD model definition.Finally we prove the efficiency of the proposed LOD models for realistic rendering with a virtual scene composed by 184 mature trees.展开更多
Good distribution of samples and weights can improve the computational accuracy and efficiency in the stochastic response analyses of aerospace problems with uncertain parameters.This work proposes a new Generalized L...Good distribution of samples and weights can improve the computational accuracy and efficiency in the stochastic response analyses of aerospace problems with uncertain parameters.This work proposes a new Generalized L2 Discrepancy based on a General Point(GL2D-GP)for generating samples and their corresponding weights.The proposed GL2D-GP is an extension of the existing discrepancy by introducing the non-same weights and a smaller box to measure probability errors.Minimizing the GL2D-GP can yield a weight optimization formula that generates a set of optimal non-identical weights for a given sample set.Through minimizing the GL2D-GP assigned to the set of optimal non-same weights,a new sample and weight generation method is developed.In the proposed method,the samples can be easily generated in terms of the generalized Halton formula with a series of optimal permutation vectors which are found by the intelligent evolutionary algorithm.Once the sample set is obtained,the optimal weights can be generated in terms of the weight optimization formula.Five numerical examples are presented to verify the high accuracy,efficiency,and strong robustness of the proposed sample generation method based on GL2D-GP.展开更多
Recombinant adenovirus serotype 5(Ad5)vector has been widely applied in vaccine development targeting infectious diseases,such as Ebola virus disease and coronavirus disease 2019(COVID-19).However,the high prevalence ...Recombinant adenovirus serotype 5(Ad5)vector has been widely applied in vaccine development targeting infectious diseases,such as Ebola virus disease and coronavirus disease 2019(COVID-19).However,the high prevalence of preexisting anti-vector immunity compromises the immunogenicity of Ad5-based vaccines.Thus,there is a substantial unmet need to minimize preexisting immunity while improving the insert-induced immunity of Ad5 vectors.Herein,we address this need by utilizing biocompatible nanoparticles to modulate Ad5–host interactions.We show that positively charged human serum albumin nanoparticles((+)HSAnp),which are capable of forming a complex with Ad5,significantly increase the transgene expression of Ad5 in both coxsackievirus–adenovirus receptor-positive and-negative cells.Furthermore,in charge-and dose-dependent manners,Ad5/(+)HSAnp complexes achieve robust(up to227-fold higher)and long-term(up to 60 days)transgene expression in the lungs of mice following intranasal instillation.Importantly,in the presence of preexisting anti-Ad5 immunity,complexed Ad5-based Ebola and COVID-19 vaccines significantly enhance antigen-specific humoral response and mucosal immunity.These findings suggest that viral aggregation and charge modification could be leveraged to engineer enhanced viral vectors for vaccines and gene therapies.展开更多
A facile one-pot, economical approach to 1,2,3-thiadiazol-5-ylureas was developed via seleniumcatalyzed oxidative carbonylation of 1,2,3-thiadiazol-5-amine with a series of amines in one-pot manner in the presence of ...A facile one-pot, economical approach to 1,2,3-thiadiazol-5-ylureas was developed via seleniumcatalyzed oxidative carbonylation of 1,2,3-thiadiazol-5-amine with a series of amines in one-pot manner in the presence of CO and O_2. This approach is featured with cheap and easily available raw materials,cheap and reusable catalyst selenium, one-pot procedure, high atomic economy, simple operations and no emission of corrosive wastes.展开更多
This paper extends the independent point-wise density interpolation to the bimaterial to pology optimization to improve the structural static or dynamic proper ties.In contras t to the conventional elemental density-b...This paper extends the independent point-wise density interpolation to the bimaterial to pology optimization to improve the structural static or dynamic proper ties.In contras t to the conventional elemental density-based topology optimization approaches,this method employs an analysis-mesh-separated material density field discretization model to describe the topology evolution of bi-material structures within the design domain.To be specific,the density design variable points can be freely positioned,independently of the field points used for discretization of the displacement field.By this means,a material interface description of relatively high quality can be achieved,even when unstructured finite element meshes and irregular-shaped elements are used in discretization of the analysis domain.Numerical examples,regarding the minimum static compliance design and the maximum fundamental eigen-frequency design,are presented to demonstrate the validity and applicability of the proposed formulation and numerical techniques.It is shown that this method is free of numerical difficulties such as checkerboard patterns and the“islanding”phenomenon.展开更多
The newly built Compact Laser Plasma Accelerator-Therapy facility at Peking University will deliver 60 J/1 Hz laser pulses with 30 fs duration.Driven by this petawatt laser facility,proton beams with energy up to 200 ...The newly built Compact Laser Plasma Accelerator-Therapy facility at Peking University will deliver 60 J/1 Hz laser pulses with 30 fs duration.Driven by this petawatt laser facility,proton beams with energy up to 200 MeV are expected to be generated for tumor therapy.During high-repetition operation,both prompt radiation and residual radiation may cause safety problems.Therefore,human radiological safety assessment before commissioning is essential.In this paper,we simulate both prompt and residual radiation using the Geant4 and FLUKA Monte Carlo codes with reasonable proton and as-produced electron beam parameters.We find that the prompt radiation can be shielded well by the concrete wall of the experimental hall,but the risk from residual radiation is nonnegligible and necessitates adequate radiation cooling.On the basis of the simulation results,we discuss the constraints imposed by radiation safety considerations on the annual working time,and we propose radiation cooling strategies for different shooting modes.展开更多
基金supported by the National Natural Science Foundation of China (No. 51176077,50976050)the Tianjin Municipal Natural Science Foundation Project(No. 12JCZDJC29300)
文摘Ce-ZrO2 is a widely used three-way catalyst support. Because of the large surface area and excellent redox quality, Ce-ZrO2 may have potential application in selective catalytic reduction （SCR） systems. In the present work, Ce-ZrO2 was introduced into a low-temperature SCR system and CeO2 and ZrO2 supports were also introduced to make a contrastive study. Mn/CeO2, Mn/ZrO2 and Mn/Ce-ZrO2 were prepared by impregnating these supports with Mn（NO3）2 solution, and have been characterized by N2-BET, XRD, TPR, TPD, XPS, FT-IR and TG. The activity and resistance to SO2 and H2O of the catalysts were investigated. Mn/Ce-ZrO2 and Mn/CeO2 were proved to have better low-temperature activities than Mn/ZrO2, and yielded 98.6% and 96.8% NO conversion at 180℃, respectively. This is mainly because Mn/Ce-ZrO2 and Mn/CeO2 had higher dispersion of manganese oxides, better redox properties and more weakly adsorbed oxygen species than Mn/ZrO2. In addition, Mn/Ce-ZrO2 showed a good resistance to SO2 and H2O and presented 87.1% NO conversion, even under SO2 and H2O treatment for 6 hours, and the activity of Mn/Ce-ZrO2 was almost restored to its original level after cutting off the injection of SO2 and H2O. This was due to the weak water absorption and weak sulfation process on the surface of the catalyst.
基金supported by the National Basic Research Program of China(973 Program)(Grant No.2011CB707705)National Natural Science Foundation of China(Grant No.81471640,81371715)the Capital Health Research and Development of Special Foundation(Grant No.2011-2015-02)
文摘Objective： To determine the value of diffusion-tensor imaging （DTI） as an adjunct to dynamic contrastenhanced magnetic resonance imaging （DCE-MRI） for improved accuracy of differential diagnosis between breast ductal carcinoma in situ （DCIS） and invasive breast carcinoma （IBC）. Methods： The MRI data of 63 patients pathologically confirmed as breast cancer were analyzed. The conventional MRI analysis metrics included enhancement style, initial enhancement characteristic, maximum slope of increase, time to peak, time signal intensity curve （TIC） pattern, and signal intensity on FS- T2WI. The values of apparent diffusion coefficient （ADC）, directionally-averaged mean diffusivity （D^vg）, exponential attenuation （EA）, fractional anisotropy （FA）, volume ratio （VR） and relative anisotropy （RA） were calculated and compared between DCIS and IBC. Multivariate logistic regression was used to identify independent factors for distinguishing IBC and DCIS. The diagnostic performance of the diagnosis equation was evaluated using the receiver operating characteristic （ROC） curve. The diagnostic efficacies of DCE- MRI, DWI and DTI were compared independently or combined. Results： EA value, lesion enhancement style and TIC pattern were identified as independent factor for differential diagnosis of IBC and DCIS. The combination diagnosis showed higher diagnostic efficacy than a single use of DCE-MRI （P=0.02）, and the area of the curve was improved from 0.84 （95% CI, 0.67-0.99） to 0.94 （95% CI, 0.85-1.00）. Conclusions： Quantitative DTI measurement as an adjunct to DCE-MRI could improve the diagnostic performance of differential diagnosis between DCIS and IBC compared to a single use of DCE-MRI.
基金Project supported by Natural Science Foundation of Hainan Province(20156242,20152033,217100,217101,ZDYF2017011)the Program of State Key Laboratory of Pollution Control and Resource Reuse(PCRRF17026)
文摘Gd^3+/TiO_(2)and Gd_(2)O_(3)/TiO_(2)nanoparticles were prepared by ball milling method.The effects of Gd^3+ion and Gd2O3 on the structure and optical property of TiO2 were studied by XRD and UV-vis DRS.Specific surface area was determined by Brunauer-Emmett-Teller(BET)method.The morphology and elemental composition were characterized by SEM-EDS.XPS was used to determine the surface compositions and chemical character of elements.The sample sizes and microstructures were observed by TEM.The photocatalytic activities of TiO2 nanoparticles modified with rare earth metal gadolinium(Gd^3+ion or Gd_(2)O_(3))were evaluated by degradation of methylene blue(MB)under UV light.Experimental results indicate that 2,5 mol%Gd^3+/TiO2 shows the best photocatalytic activity compared with Gd2O3/TiO2 and pure TiO2.The existence of gadolinium can exhibit the aggregation and induce lattice distortion of TiO2 obtained from XRD,SEM and TEM results.The band gap energy of 2.5 mol%Gd^3+/TiO2 decreases to3.07 eV and it leads to visible light absorption response which can be seen from UV-vis absorption spectra.The surface area of 2.5 mol%Gd^3+/TiO2 equals to 85.8 m^2/g and average crystal size is 21.1 nm.EDS and XPS analyses reveal that gadolinium can be introduced either into TiO2 lattice or adsorbed on the surface of TiO2.The content of surface OH groups in 2.5 mol%Gd^3+/TiO2 is 50,88%(1.55 times higher than that of pure TiO2)and the content of lattice oxygen decreases to 11.26%.The MB(25 mg/L)degradation reaction rate constants of 2,5 mol%Gd^3+/TiO2,0.5 mol%Gd2O3/TiO2 and pure TiO2 were0.0713,0.0588 and 0.0263 min^-1,respectively.The degradation rates of rhodamine B(30 mg/L)in 60 min are 97,9%,90.1%and 84.6%for 2,5 mol%Gd^3+/TiO2,0.5 mol%Gd2O3/TiO2 and pure TiO2,respectively.
基金Supported by the National Natural Science Foundation of China(Grant Nos.21506019,51672118,51672117)the Fundamental Research Funds for the Central Universities(Grant Nos.DUT16RC(4)80,DUT16QY43)the Program for Changjiang Scholars(T2012049)
文摘Membrane separation has become an important technology to deal with the global water crisis. The polymerbased membrane technology is currently in the forefront of water purification and desalination but is plagued with some bottlenecks. Laminated graphene oxide(GO) membranes exhibit excellent advantages in water purification and desalination due to the single atomic layer structure, hydrophilic property, rich oxygen-containing groups for modification, mechanical and chemical robust, anti-fouling properties, facile and large-scale production, etc. Thus the GO-based membrane technology is believed to offer huge opportunities for efficient and practical water treatment. This review systematically summarizes the current progress on the water flux and selectivity intensification, stability improvement, anti-fouling and anti-biofouling ability enhancement by structural control and modification. To improve the performance of the laminated GO membrane, interlayer spacing tunability and surface modification are mainly used to enhance its water flux and selectivity. It is found that the stability and biofouling also block the service life of the GO membrane. The crosslinking method is found to effectively solve the stability of GO membrane in aqueous environment. Introducing nanoparticles is a widely used method to improve the membrane biofouling ability. Overall, we believe that this review could provide benefit to researchers in the area of GO-based membrane technology for water treatment.
基金Project supported by the Natural Science Foundation of Hainan Province(20156242,217100,217101,20152033)Science and Technology Department of Hainan Province(ZDYF2017011)
文摘Ball milling method was applied to prepare Lu^3＋/TiO2 photocatalysts. The catalysts were characterized with X-ray powder diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, UV-visible diffuse reflectance spectra（UV-vis DRS）, energy dispersive X-ray spectrometer（EDS）, transmission electron microscopy（TEM） and Brunauer-Emmett-Teller（BET） method. The photocatalytic activities were determined by the degradation of methylene blue（MB） equipped with a 300 W medium pressure mercury lamp. Results show that the first order reaction rate constants of Lu^3＋/TiO2 and pure TiO2 are0.0565 and 0.0263 min-1, respectively, which both were evaluated under the condition of catalysts loading of 0.2 g/L,initial concentration of 25 mg/L for MB, mole ratio of Lu^3＋/TiO2 of 1.5% and milling time of 4 h. The average crystal sizes of 1.5 mol% Lu^3＋/TiO2 and pure TiO2 are 18.7 and 19.3 nm, respectively.
基金supported by the National Natural Science Foundation of China(Grant No.12102079).
文摘Design and application of tunable phononic crystals(PnCs)are attracting increasing interest due to their promising capabilities to manipulate acoustic and elastic waves effectively.This paper investigates topology optimization of the magnetorheological(MR)materials including PnCs for opening the tunable and wide bandgaps.Therein,the bandgap tunability of the PnCs is achieved by shear modulus variation of MR materials under a continuously changing applied magnetic field.The pseudo elemental densities representing the bi-material distribution inside the PnC unit cell are taken as design variables and interpolated with an artificial MR penalization model.An aggregated bandgap index for enveloping the extreme values ofbandgap width and tunable range of the MR included smart PnCs is proposed as the objective function.In this context,the sensitivity analysis scheme is derived,and the optimization problem is solved with the gradient-based mathematical programming method.The effectiveness of the proposed optimization method is demonstrated by numerical examples,where the optimized solutions present tunable and stably wide bandgap characteristics under different magnetic fields.The tunable optimized PnCs based device that can provide a wider tunable bandgap range is also explored.
基金the financial supports from the National Natural Science Foundation of China(51978124)Science Fund for Creative Research Groups of the National Natural Science Foundation of China(22021005)the Cheung Kong Scholars Programme of China(T2012049)。
文摘Catalytic oxidation of Hgo to Hg~O is an efficient way to remove Hg^(0) from coal-fired flue gas.The catalyst with ordered pore structure can lower mass transfer resistance resulting in higher Hg^(0) oxidation efficiency.Therefore,in the present work,wood vessels were used as sacrificial template to obtain Co_(3)O_(4) with ordered pore structure.SEM and BET results show that,when the mass concentrations of Co(NO_(3))_(2)·6H_(2)O was 20%,the obtained catalyst(Co_(3)O_(4) [20%Co(NO_(3))_(2)])possesses better pore structure and higher surface area.It will expose more available surface active sites and lower the mass transfer resistance.Furthermore,XPS results prove that Co_(3)O_(4) [20%Co(NO_(3))_(2)]has the highest ratio of chemisorbed oxygen which plays an important role in Hg^(0) oxidation process.These results lead to a better Hg^(0) oxidation efficiency of Co_(3)O_(4) [20%Co(NO_(3))_(2)],which is about 90%in the temperature range of 200 to 350℃,Furthermore,Co_(3)O_(4) [20%Co(NO_(3))_(2)]has a stable catalytic activity,and its Hg^(0) oxidation efficiency maintains above 90%at 250℃even after 90 h test,A probable reaction mechanism is deduced by the XPS results of the fresh,used and regenerated catalyst of Co_(3)O_(4) [20%Co(NO3)2].Chemisorbed oxygen can react with Hg^(0) forming HgO with the reduction of Co^(3+)to Co^(2)+.And lattice oxygen and gaseous oxygen can supplement the consumption of chemisorbed oxygen to oxidize Co^(2+)to Co^(3+).
基金generous support provided by the National Natural Science Foundation of China (Nos. 51378253 and 51522805)the Discipline Crossing Foundation of Nanjing University
文摘An efficient and profitable separation process was proposed to prepare 5N （the purity of the metal solution reaches 99.999%） high-purity nickel from 3N nickel-solutions using Purolite S984. The adsorption performance of this superior resin, especially its selectivity for metal ions, was explored quantitatively. The maximum adsorption capacity for copper was 2.286 mmol/g calculated by the Langmuir model, which was twice as large as that for nickel. In the binary systems, the adsorption capacity for nickel was decreased by 45%, indicating direct competition for the active sites. The infinite separation factor for copper versus nickel exceeded 300, revealing the feasibility of preparing 5N-level high-purity nickel solutions, which was further verified using the 800 BV （bed volume） effluent in the column dynamic process. According to the cost-benefit analysis, purification contributed to a profit of approximately 60,000 USD per cycle, and the investment return period was less than 1/3 years. Density functional theory analysis confirmed that four nitrogen atoms would be involved in the coordination complex and thus a structure involving two five-membered rings could be achieved. The X-ray photoelectron spectra confirmed the involvement of nitrogen atoms, implying a coordination ratio of approximately 1：1.
文摘Dear Editor,Vesicovaginal fistula(VVF)is an abnormal opening between the urinary bladder and the vagina.The condition has an immense psychological effect on patients due to the continuous leakage of urine or watery vaginal discharge.The wet feeling and foul smell associated with leakage of urine cause social outcasting of the patients.This leads to immense emotional trauma and makes life miserable for the patient.The most common etiology for VVF in developing countries is obstructed labour[1],and in developed countries,it is abdominal hysterectomy[2].VVF poses a challenging problem to the surgeon.The location and the size of the fistula determine the extent of the patients’symptoms.
基金This work is supported by National Natural Science Foundation of China projects No. 60073007, 60473110, 30371157 by National High-Tech Research and Development Plan of China under Grant No. 2006AA01Z301+1 种基金 by the French National Research Agency within project NATSIM ANR-05-MMSA-45 and by LIAMA funding with the project GreenLab.
文摘Realistic modelling and interactive rendering of forestry and landscape is a challenge in computer graphics and virtual reality.Recent new developments in plant growth modelling and simulation lead to plant models faithful to botanical structure and development,not only representing the complex architecture of a real plant but also its functioning in interaction with its environment.Complex geometry and material of a large group of plants is a big burden even for high performances computers,and they often overwhelm the numerical calculation power and graphic rendering power.Thus,in order to accelerate the rendering speed of a group of plants,software techniques are often developed.In this paper,we focus on plant organs,i.e.leaves,flowers,fruits and inter-nodes.Our approach is a simplification process of all sparse organs at the same time,i.e.,Level of Detail(LOD),and multi-resolution models for plants.We do explain here the principle and construction of plant simplification.They are used to construct LOD and multi-resolution models of sparse organs and branches of big trees.These approaches take benefit from basic knowledge of plant architecture,clustering tree organs according to biological structures.We illustrate the potential of our approach on several big virtual plants for geometrical compression or LOD model definition.Finally we prove the efficiency of the proposed LOD models for realistic rendering with a virtual scene composed by 184 mature trees.
基金the support of the National Natural Science Foundation of China(Nos.12372190,12272077)the Fundamental Research Funds for the Central Universities,China(Nos.DUT20RC(5)009,DUT20GJ216).
文摘Good distribution of samples and weights can improve the computational accuracy and efficiency in the stochastic response analyses of aerospace problems with uncertain parameters.This work proposes a new Generalized L2 Discrepancy based on a General Point(GL2D-GP)for generating samples and their corresponding weights.The proposed GL2D-GP is an extension of the existing discrepancy by introducing the non-same weights and a smaller box to measure probability errors.Minimizing the GL2D-GP can yield a weight optimization formula that generates a set of optimal non-identical weights for a given sample set.Through minimizing the GL2D-GP assigned to the set of optimal non-same weights,a new sample and weight generation method is developed.In the proposed method,the samples can be easily generated in terms of the generalized Halton formula with a series of optimal permutation vectors which are found by the intelligent evolutionary algorithm.Once the sample set is obtained,the optimal weights can be generated in terms of the weight optimization formula.Five numerical examples are presented to verify the high accuracy,efficiency,and strong robustness of the proposed sample generation method based on GL2D-GP.
基金supported in part by the grant from National Natural Science Foundation of China(82171818,81703048,82041019,and 82101919)the grant from Defense Industrial Technology Development Program of China(JCKY2020802B001)Beijing Municipal Science and Technology Commission(Z201100005420024)。
文摘Recombinant adenovirus serotype 5(Ad5)vector has been widely applied in vaccine development targeting infectious diseases,such as Ebola virus disease and coronavirus disease 2019(COVID-19).However,the high prevalence of preexisting anti-vector immunity compromises the immunogenicity of Ad5-based vaccines.Thus,there is a substantial unmet need to minimize preexisting immunity while improving the insert-induced immunity of Ad5 vectors.Herein,we address this need by utilizing biocompatible nanoparticles to modulate Ad5–host interactions.We show that positively charged human serum albumin nanoparticles((+)HSAnp),which are capable of forming a complex with Ad5,significantly increase the transgene expression of Ad5 in both coxsackievirus–adenovirus receptor-positive and-negative cells.Furthermore,in charge-and dose-dependent manners,Ad5/(+)HSAnp complexes achieve robust(up to227-fold higher)and long-term(up to 60 days)transgene expression in the lungs of mice following intranasal instillation.Importantly,in the presence of preexisting anti-Ad5 immunity,complexed Ad5-based Ebola and COVID-19 vaccines significantly enhance antigen-specific humoral response and mucosal immunity.These findings suggest that viral aggregation and charge modification could be leveraged to engineer enhanced viral vectors for vaccines and gene therapies.
基金financial support from the National Natural Science Foundation of China(No.21772033)Program for Innovative Research Team in Science and Technology in University of Henan Province(No. 15IRTSTHN003)
文摘A facile one-pot, economical approach to 1,2,3-thiadiazol-5-ylureas was developed via seleniumcatalyzed oxidative carbonylation of 1,2,3-thiadiazol-5-amine with a series of amines in one-pot manner in the presence of CO and O_2. This approach is featured with cheap and easily available raw materials,cheap and reusable catalyst selenium, one-pot procedure, high atomic economy, simple operations and no emission of corrosive wastes.
基金The financial support of the National Natural Science Foundation of China(11425207,U1508209)is gratefully acknowledged.
文摘This paper extends the independent point-wise density interpolation to the bimaterial to pology optimization to improve the structural static or dynamic proper ties.In contras t to the conventional elemental density-based topology optimization approaches,this method employs an analysis-mesh-separated material density field discretization model to describe the topology evolution of bi-material structures within the design domain.To be specific,the density design variable points can be freely positioned,independently of the field points used for discretization of the displacement field.By this means,a material interface description of relatively high quality can be achieved,even when unstructured finite element meshes and irregular-shaped elements are used in discretization of the analysis domain.Numerical examples,regarding the minimum static compliance design and the maximum fundamental eigen-frequency design,are presented to demonstrate the validity and applicability of the proposed formulation and numerical techniques.It is shown that this method is free of numerical difficulties such as checkerboard patterns and the“islanding”phenomenon.
基金supported by the National Natural Science Foundation of China(Grant No.12205008)the NSFC Innovation Group Project(Grant No.11921006)+1 种基金the National Grand Instrument Project(Grant Nos.2019YFF01014402 and 2019YFF01014403)the National Science Fund for Distinguished Young Scholars(Grant No.12225501).
文摘The newly built Compact Laser Plasma Accelerator-Therapy facility at Peking University will deliver 60 J/1 Hz laser pulses with 30 fs duration.Driven by this petawatt laser facility,proton beams with energy up to 200 MeV are expected to be generated for tumor therapy.During high-repetition operation,both prompt radiation and residual radiation may cause safety problems.Therefore,human radiological safety assessment before commissioning is essential.In this paper,we simulate both prompt and residual radiation using the Geant4 and FLUKA Monte Carlo codes with reasonable proton and as-produced electron beam parameters.We find that the prompt radiation can be shielded well by the concrete wall of the experimental hall,but the risk from residual radiation is nonnegligible and necessitates adequate radiation cooling.On the basis of the simulation results,we discuss the constraints imposed by radiation safety considerations on the annual working time,and we propose radiation cooling strategies for different shooting modes.
