Teleseismic traveltime tomography is an important tool for investigating the crust and mantle structure of the Earth.The imaging quality of teleseismic traveltime tomography is affected by many factors,such as mantle ...Teleseismic traveltime tomography is an important tool for investigating the crust and mantle structure of the Earth.The imaging quality of teleseismic traveltime tomography is affected by many factors,such as mantle heterogeneities,source uncertainties and random noise.Many previous studies have investigated these factors separately.An integral study of these factors is absent.To provide some guidelines for teleseismic traveltime tomography,we discussed four main influencing factors:the method for measuring relative traveltime differences,the presence of mantle heterogeneities outside the imaging domain,station spacing and uncertainties in teleseismic event hypocenters.Four conclusions can be drawn based on our analysis.(1)Comparing two methods,i.e.,measuring the traveltime difference between two adjacent stations(M1)and subtracting the average traveltime of all stations from the traveltime of one station(M2),reveals that both M1 and M2 can well image the main structures;while M1 is able to achieve a slightly higher resolution than M2;M2 has the advantage of imaging long wavelength structures.In practical teleseismic traveltime tomography,better tomography results can be achieved by a two-step inversion method.(2)Global mantle heterogeneities can cause large traveltime residuals(up to about 0.55 s),which leads to evident imaging artifacts.(3)The tomographic accuracy and resolution of M1 decrease with increasing station spacing when measuring the relative traveltime difference between two adjacent stations.(4)The traveltime anomalies caused by the source uncertainties are generally less than 0.2 s,and the impact of source uncertainties is negligible.展开更多
It is well known that quantitative estimation of slip distributions on fault plane is one of the most important issues for earthquake source inversion related to the fault rupture process. The characteristics of slip ...It is well known that quantitative estimation of slip distributions on fault plane is one of the most important issues for earthquake source inversion related to the fault rupture process. The characteristics of slip distribution on the main fault play a fundamental role to control strong ground motion pattern. A large amount of works have also suggested that variable slip models inverted from longer period ground motion recordings are relevant for the prediction of higher frequency ground motions. Zhang et al. (Chin J Geophys 56:1412-1417, 2013) and Wang et al. (Chin J Geophys 56:1408-1411,2013) published their source inversions for the fault rupturing process soon after the April 20, 2013 Lushan earthquake in Sichuan, China. In this study, first, we synthesize two forward source slip models: the value of maximum slip, fault dimension, size, and dimension of major asperities, and comer wave number obtained from Wang's model is adopted to constrain the gen- eration of k-2 model and crack model. Next, both inverted and synthetic slip models are employed to simulate the ground motions for the Lushan earthquake based on the stochastic finite-fault method. In addition, for a comparison purpose, a stochastic slip model and another k-2 model (k 2 model II) with 2 times value of comer wave number of the original k-2 model (k 2 model I) are also employed for simulation for Lushan event. The simulated results characterized by Modified Mer- calli Intensity (MMI) show that the source slip models based on the inverted and synthetic slip distributions could capture many basic features associated with the ground motion patterns. Moreover, the simulated MMI distributions reflect the rupture directivity effect and the influence of the shallow velocity structure well. On the other hand, the simulated MMI bystochastic slip model and k 2 model II is apparently higher than observed intensity. By contrast, our simulation results show that the higher frequency ground motion is sensitive to the degree of slip roughness; therefore, we suggest that, for realistic ground- motion simulations due to future earthquake, it is imperative to properly estimate the slip roughness distribution.展开更多
In general, earthquake cycle related to earthquake faulting could include four major processes which could be described by (1) fault locking, (2) self-acceleration or nucleation (possible foreshocks), (3) cose...In general, earthquake cycle related to earthquake faulting could include four major processes which could be described by (1) fault locking, (2) self-acceleration or nucleation (possible foreshocks), (3) coseismic slip, and (4) post-stress relaxation and afterslip. A sudden static stress change/perturbation in the surrounding crust can advance/ delay the fault instability or failure time and modify earth- quake rates. Based on a simple one-dimensional spring-sli- der block model with the combination of rate-and-state- dependent friction relation, in this study, we have approxi- mately derived the simple analytical solutions of clock advance/delay of fault failures caused by a sudden static Coulomb stress change applied in the different temporal evolution periods during an earthquake faulting. The results have been used in the physics-based explanation of delayed characteristic earthquake in Parkfield region, California, in which the next characteristic earthquake of M 6.0 after 1966 occurred in 2004 instead of around 1988 according to its characteristic return period of 22 years. At the same time, the analytical solutions also indicate that the time advance/ delay in Coulomb stress change derived by the dislocation model has a certain limitation and fundamental flaw. Fur- thermore, we discussed the essential difference between rate- and state-variable constitutive (R-S) model and Coulomb stress model used commonly in current earthquake triggering study, and demonstrated that, in fact, the Coulomb stress model could be involved in the R-S model. The results, we have obtained in this study, could be used in the development of time-dependent fault interaction model and the probability calculation related to the time-dependent and renewal earthquake prediction model.展开更多
Bacteria-mediated anti-tumor therapy has received widespread attention due to its natural tumor-targeting ability and specific immune-activation characteristics.It has made significant progress in breaking the limitat...Bacteria-mediated anti-tumor therapy has received widespread attention due to its natural tumor-targeting ability and specific immune-activation characteristics.It has made significant progress in breaking the limitations of monotherapy and effectively eradicating tumors,especially when combined with traditional therapy,such as radiotherapy.According to their different biological characteristics,bacteria and their derivatives can not only improve the sensitivity of tumor radiotherapy but also protect normal tissues.Moreover,genetically engineered bacteria and bacteria-based biomaterials have further expanded the scope of their applications in radiotherapy.In this review,we have summarized relevant researches on the application of bacteria and its derivatives in radiotherapy in recent years,expounding that the bacteria,bacterial derivatives and bacteria-based biomaterials can not only directly enhance radiotherapy but also improve the anti-tumor effect by improving the tumor microenvironment(TME)and immune effects.Furthermore,some probiotics can also protect normal tissues and organs such as intestines from radiation via anti-inflammatory,anti-oxidation and apoptosis inhibition.In conclusion,the prospect of bacteria in radiotherapy will be very extensive,but its biological safety and mechanism need to be further evaluated and studied.展开更多
The northeastern Tibetan Plateau serves as the frontier for the northeastward expansion of the plateau.In this area,the Tibetan Plateau interacts with the surrounding blocks,such as the Alxa Block,the Ordos Block,the ...The northeastern Tibetan Plateau serves as the frontier for the northeastward expansion of the plateau.In this area,the Tibetan Plateau interacts with the surrounding blocks,such as the Alxa Block,the Ordos Block,the Kunlun-West Qinling belt and the Sichuan Basin.Because of this expansion and interaction,this area suffers from intense deformation.At present,the evolution and deformation mechanisms of the northeastern Tibetan Plateau remain controversial.To provide new insights into these mechanisms,in this study,we conduct tomography of the P-wave velocity and radial anisotropy structures beneath the northeastern Tibetan Plateau.We choose a total of 667 teleseismic earthquakes from August 2006 to October 2020.Waveforms of these earthquakes were recorded by 921 broadband seismic stations in the northeastern Tibetan Plateau and surrounding areas.We first perform cross-correlation on waveforms of each station pair and obtain 770,749 P-wave traveltime differences.Then,we invert the differential traveltime data by applying eikonal equation-based teleseismic tomography.Finally,the P-wave velocity and radial anisotropy structures at depths from 30 to 800 km below the northeastern Tibetan Plateau are obtained.Our tomographic model shows clear low-velocity anomalies and positive radial anisotropy in the lower crust under the northeastern Qilian orogen,the northeastern Songpan-Ganzi belt and the western Qinling fold zone.These features are integrated to demonstrate the existence of lower crustal flow in the study area.Prominent low-velocity anomalies and positive radial anisotropy are found in the uppermost mantle beneath the Qilian orogen,the northeastern Songpan-Ganzi belt and western Qinling fold zone.These characteristics are combined to infer a weak lithosphere and horizontal asthenospheric flow under these tectonic units.Both the Ordos Block and the Sichuan Basin exhibit clear high-velocity anomalies and negative radial anisotropy in the uppermost mantle,thereby reflecting the high mechanical strength of the lithosphere beneath these blocks.High-velocity anomalies are also present in the upper mantle under the northern Chuandian block,potentially implying the northward subduction of the Indian plate.Furthermore,the front of the subducted Indian plate is imaged close to the Xianshuihe fault rather than the Kunlun fault.展开更多
electrolyte. The properties of lithium-ion (Li-ion) battery, such as cycle life, irreversible capacity loss, self-discharge rate, electrode corrosion and safety are usually ascribed to the quality of the SEI, which ar...electrolyte. The properties of lithium-ion (Li-ion) battery, such as cycle life, irreversible capacity loss, self-discharge rate, electrode corrosion and safety are usually ascribed to the quality of the SEI, which are highly dependent on the thickness. Thus, understanding the formation mechanism and the SEI thickness is of prime interest. First, we apply dimensional analysis to obtain an explicit relation between the thickness and the number density in this study. Then the SEI thickness in the initial charge-discharge cycle is analyzed and estimated for the first time using the Cahn-Hilliard phase-field model. In addition, the SEI thickness by molecular dynamics simulation validates the theoretical results. It has been shown that the established model and the simulation in this paper estimate the SEI thickness concisely within order-of-magnitude of nanometers. Our results may help in evaluating the performance of SEI and assist the future design of Li-ion battery.展开更多
Radionuclides have been widely used for multimodal imaging and radioisotope therapy of cancer.Various nanomaterials have been developed as excellent nanocarriers of radionuclides for the targeted delivery into tumors,...Radionuclides have been widely used for multimodal imaging and radioisotope therapy of cancer.Various nanomaterials have been developed as excellent nanocarriers of radionuclides for the targeted delivery into tumors,in order to minimize the unnecessary side effect and enhance the therapeutic efficacy of radiotherapy.Among those nanomaterials,gold nanomaterials with tunable morphologies,easy modification,good biological safety,and radiation sensitization capability are excellent candidates for cancer theranostics.Given the superior performance of gold-based nanomaterials in biomedicine,we summary the recent advance of radionuclide labeled/doped gold-based nanomaterials for cancer theranostics.In this review article,we will discuss the methods for labelling or doping radionuclides onto gold nanomaterials,their applications for nuclear imaging and Cerenkov luminescence(CL)imaging,as well as the radioisotope therapy of cancer,and finally the toxicity evaluation of radionuclide labeled/doped gold-based nanomaterials.We hope that our review article would provide guidance for non-experts to design the radiolabeled nanomaterials for cancer imaging guided therapy.展开更多
Volatile organic pollutants such as benzene and formaldehyde are commonly detected in the ambient air of paper mills.To remove these pollutants from the air,a photo-catalytic reactor was developed in this study.The re...Volatile organic pollutants such as benzene and formaldehyde are commonly detected in the ambient air of paper mills.To remove these pollutants from the air,a photo-catalytic reactor was developed in this study.The reactor had a series of honeycomb aluminum meshes coated with nanosized titanium dioxide as the catalyst for the degradation reactions of gaseous pollutants.Both formaldehyde and benzene could be completely degraded in the reactor.However,the degrading time for benzene was much longer than that for formaldehyde,and the degradation rate of benzene decreased with increasing initial benzene concentration.It was found that the reaction pathway for formaldehyde in the mixture was different from that in its single component form,and it took about two times longer time to be degraded than that for its single component form.The reaction pathway of benzene was similar in either case although the degradation time for benzene was about 50%shorter in the mixture form.展开更多
Photo-electro-catalytic(PEC)oxidation has been widely recognized as an effective technology for advanced treatment of papermaking wastewater.To optimize the oxidation process,it is important of monitor continuously th...Photo-electro-catalytic(PEC)oxidation has been widely recognized as an effective technology for advanced treatment of papermaking wastewater.To optimize the oxidation process,it is important of monitor continuously the chemical oxygen demand(COD)of inflow and outflow wastewater.However,online COD sensors are expensive difficult to maintain,and therefore COD is usually analyzed off-line in laboratories in most cases.The objective of this study is to develop an inexpensive method for on-line COD measurement.The oxidation-reduction potential(ORP),pH,and dissolved oxygen(DO)of wastewater were selected as the key parameters,which consists of four different types of artificial neural network(ANNs)methods:multi-layer perceptron neural network(MLP),back propagation neural network(BPNN),radial basis neural network(RBNN)and generalized regression neural network(GRNN).These parameters were applied in the development of COD soft-sensing models.Six batches of papermaking wastewater with different pollution loads were treated with PEC technology over a period of 90 minutes,and a total of 546 data points was collected,including the on-line measurements of ORP,pH and DO,as well as off-line COD data.The 546 data points were divided into training set(410 data,75%of total)and validation set(136 data,25%of total).Four statistical criteria,namely,root mean square error(RMSE),mean absolute error(MAE),mean absolute relative error(MARE),and determination coefficient(R2)were used to assess the performance of the models developed with the training set of data.The comparison of results for the four ANN models for COD soft-sensing indicated that the RBNN model behaved most favorably,which possessed precise and predictable results with R2=0.913 for the validation set.Lastly,the proposed RBNN model was applied to a new batch of PEC oxidation of papermaking wastewater,and the results indicated that the model could be applied successfully for COD soft-sensing for the wastewater.展开更多
基金supported by the National Institute of Natural Hazards,Ministry of Emergency Management of China(No.ZDJ2019-18)the Open Fund Project of the State Key Laboratory of Lithospheric Evolution(No.SKL-K202101)+1 种基金the National Natural Science Foundation of China(Nos.42174111 and 42064004)the National Natural Science Foundation of China(No.U1839206).
文摘Teleseismic traveltime tomography is an important tool for investigating the crust and mantle structure of the Earth.The imaging quality of teleseismic traveltime tomography is affected by many factors,such as mantle heterogeneities,source uncertainties and random noise.Many previous studies have investigated these factors separately.An integral study of these factors is absent.To provide some guidelines for teleseismic traveltime tomography,we discussed four main influencing factors:the method for measuring relative traveltime differences,the presence of mantle heterogeneities outside the imaging domain,station spacing and uncertainties in teleseismic event hypocenters.Four conclusions can be drawn based on our analysis.(1)Comparing two methods,i.e.,measuring the traveltime difference between two adjacent stations(M1)and subtracting the average traveltime of all stations from the traveltime of one station(M2),reveals that both M1 and M2 can well image the main structures;while M1 is able to achieve a slightly higher resolution than M2;M2 has the advantage of imaging long wavelength structures.In practical teleseismic traveltime tomography,better tomography results can be achieved by a two-step inversion method.(2)Global mantle heterogeneities can cause large traveltime residuals(up to about 0.55 s),which leads to evident imaging artifacts.(3)The tomographic accuracy and resolution of M1 decrease with increasing station spacing when measuring the relative traveltime difference between two adjacent stations.(4)The traveltime anomalies caused by the source uncertainties are generally less than 0.2 s,and the impact of source uncertainties is negligible.
基金supported by the CAS/SAFEA International Partnership Program for Creative Research Teams(KZZD-EW-TZ-19)
文摘It is well known that quantitative estimation of slip distributions on fault plane is one of the most important issues for earthquake source inversion related to the fault rupture process. The characteristics of slip distribution on the main fault play a fundamental role to control strong ground motion pattern. A large amount of works have also suggested that variable slip models inverted from longer period ground motion recordings are relevant for the prediction of higher frequency ground motions. Zhang et al. (Chin J Geophys 56:1412-1417, 2013) and Wang et al. (Chin J Geophys 56:1408-1411,2013) published their source inversions for the fault rupturing process soon after the April 20, 2013 Lushan earthquake in Sichuan, China. In this study, first, we synthesize two forward source slip models: the value of maximum slip, fault dimension, size, and dimension of major asperities, and comer wave number obtained from Wang's model is adopted to constrain the gen- eration of k-2 model and crack model. Next, both inverted and synthetic slip models are employed to simulate the ground motions for the Lushan earthquake based on the stochastic finite-fault method. In addition, for a comparison purpose, a stochastic slip model and another k-2 model (k 2 model II) with 2 times value of comer wave number of the original k-2 model (k 2 model I) are also employed for simulation for Lushan event. The simulated results characterized by Modified Mer- calli Intensity (MMI) show that the source slip models based on the inverted and synthetic slip distributions could capture many basic features associated with the ground motion patterns. Moreover, the simulated MMI distributions reflect the rupture directivity effect and the influence of the shallow velocity structure well. On the other hand, the simulated MMI bystochastic slip model and k 2 model II is apparently higher than observed intensity. By contrast, our simulation results show that the higher frequency ground motion is sensitive to the degree of slip roughness; therefore, we suggest that, for realistic ground- motion simulations due to future earthquake, it is imperative to properly estimate the slip roughness distribution.
文摘In general, earthquake cycle related to earthquake faulting could include four major processes which could be described by (1) fault locking, (2) self-acceleration or nucleation (possible foreshocks), (3) coseismic slip, and (4) post-stress relaxation and afterslip. A sudden static stress change/perturbation in the surrounding crust can advance/ delay the fault instability or failure time and modify earth- quake rates. Based on a simple one-dimensional spring-sli- der block model with the combination of rate-and-state- dependent friction relation, in this study, we have approxi- mately derived the simple analytical solutions of clock advance/delay of fault failures caused by a sudden static Coulomb stress change applied in the different temporal evolution periods during an earthquake faulting. The results have been used in the physics-based explanation of delayed characteristic earthquake in Parkfield region, California, in which the next characteristic earthquake of M 6.0 after 1966 occurred in 2004 instead of around 1988 according to its characteristic return period of 22 years. At the same time, the analytical solutions also indicate that the time advance/ delay in Coulomb stress change derived by the dislocation model has a certain limitation and fundamental flaw. Fur- thermore, we discussed the essential difference between rate- and state-variable constitutive (R-S) model and Coulomb stress model used commonly in current earthquake triggering study, and demonstrated that, in fact, the Coulomb stress model could be involved in the R-S model. The results, we have obtained in this study, could be used in the development of time-dependent fault interaction model and the probability calculation related to the time-dependent and renewal earthquake prediction model.
基金partially supported by the National Natural Science Foundation of China(U1932208,32171382)Key Research and Development Program of Social Development of Jiangsu Province(BE2022725,China)+2 种基金Hui-Chun Chin and Tsung-Dao Lee Chinese Undergraduate Research Endowment(CURE,China)Undergraduate Training Program for Innovation and Entrepreneurship Soochow University(202010285046Z,China)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD,China)。
文摘Bacteria-mediated anti-tumor therapy has received widespread attention due to its natural tumor-targeting ability and specific immune-activation characteristics.It has made significant progress in breaking the limitations of monotherapy and effectively eradicating tumors,especially when combined with traditional therapy,such as radiotherapy.According to their different biological characteristics,bacteria and their derivatives can not only improve the sensitivity of tumor radiotherapy but also protect normal tissues.Moreover,genetically engineered bacteria and bacteria-based biomaterials have further expanded the scope of their applications in radiotherapy.In this review,we have summarized relevant researches on the application of bacteria and its derivatives in radiotherapy in recent years,expounding that the bacteria,bacterial derivatives and bacteria-based biomaterials can not only directly enhance radiotherapy but also improve the anti-tumor effect by improving the tumor microenvironment(TME)and immune effects.Furthermore,some probiotics can also protect normal tissues and organs such as intestines from radiation via anti-inflammatory,anti-oxidation and apoptosis inhibition.In conclusion,the prospect of bacteria in radiotherapy will be very extensive,but its biological safety and mechanism need to be further evaluated and studied.
基金supported by the National Institute of Natural Hazards, Ministry of Emergency Management of China (Grant No. ZDJ2019-18)supported by the National Natural Science Foundation of China (Grant No. U1839206)+2 种基金supported by the Open Fund Project of the State Key Laboratory of Lithospheric Evolution (Grant No. SKL-K202101)the National Natural Science Foundation of China (Grant Nos. 42174111 and 42064004)Institute of Geophysics, China Earthquake Administration (Grant Nos. DQJB16A03, DQJB17A01)
文摘The northeastern Tibetan Plateau serves as the frontier for the northeastward expansion of the plateau.In this area,the Tibetan Plateau interacts with the surrounding blocks,such as the Alxa Block,the Ordos Block,the Kunlun-West Qinling belt and the Sichuan Basin.Because of this expansion and interaction,this area suffers from intense deformation.At present,the evolution and deformation mechanisms of the northeastern Tibetan Plateau remain controversial.To provide new insights into these mechanisms,in this study,we conduct tomography of the P-wave velocity and radial anisotropy structures beneath the northeastern Tibetan Plateau.We choose a total of 667 teleseismic earthquakes from August 2006 to October 2020.Waveforms of these earthquakes were recorded by 921 broadband seismic stations in the northeastern Tibetan Plateau and surrounding areas.We first perform cross-correlation on waveforms of each station pair and obtain 770,749 P-wave traveltime differences.Then,we invert the differential traveltime data by applying eikonal equation-based teleseismic tomography.Finally,the P-wave velocity and radial anisotropy structures at depths from 30 to 800 km below the northeastern Tibetan Plateau are obtained.Our tomographic model shows clear low-velocity anomalies and positive radial anisotropy in the lower crust under the northeastern Qilian orogen,the northeastern Songpan-Ganzi belt and the western Qinling fold zone.These features are integrated to demonstrate the existence of lower crustal flow in the study area.Prominent low-velocity anomalies and positive radial anisotropy are found in the uppermost mantle beneath the Qilian orogen,the northeastern Songpan-Ganzi belt and western Qinling fold zone.These characteristics are combined to infer a weak lithosphere and horizontal asthenospheric flow under these tectonic units.Both the Ordos Block and the Sichuan Basin exhibit clear high-velocity anomalies and negative radial anisotropy in the uppermost mantle,thereby reflecting the high mechanical strength of the lithosphere beneath these blocks.High-velocity anomalies are also present in the upper mantle under the northern Chuandian block,potentially implying the northward subduction of the Indian plate.Furthermore,the front of the subducted Indian plate is imaged close to the Xianshuihe fault rather than the Kunlun fault.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11372313, U1562105, and 11611130019)the Chinese Academy of Sciences (CAS) through CAS Interdisciplinary Innovation Team Project, the CAS Key Research Program of Frontier Sciences (Grant No. QYZDJ-SSW-JSC019)the CAS Strategic Priority Research Program (Grant No. XDB22040401)
文摘electrolyte. The properties of lithium-ion (Li-ion) battery, such as cycle life, irreversible capacity loss, self-discharge rate, electrode corrosion and safety are usually ascribed to the quality of the SEI, which are highly dependent on the thickness. Thus, understanding the formation mechanism and the SEI thickness is of prime interest. First, we apply dimensional analysis to obtain an explicit relation between the thickness and the number density in this study. Then the SEI thickness in the initial charge-discharge cycle is analyzed and estimated for the first time using the Cahn-Hilliard phase-field model. In addition, the SEI thickness by molecular dynamics simulation validates the theoretical results. It has been shown that the established model and the simulation in this paper estimate the SEI thickness concisely within order-of-magnitude of nanometers. Our results may help in evaluating the performance of SEI and assist the future design of Li-ion battery.
基金This work was partially supported by National Natural Science Foundation of China(31822022,U1932208,31900986)a Jiangsu Natural Science Fund for Outstanding Youth Science Foundation(BK20180094)+1 种基金the Foundation of Jiangsu Provincial Medical Innovation Team(CXTDA2017042)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Radionuclides have been widely used for multimodal imaging and radioisotope therapy of cancer.Various nanomaterials have been developed as excellent nanocarriers of radionuclides for the targeted delivery into tumors,in order to minimize the unnecessary side effect and enhance the therapeutic efficacy of radiotherapy.Among those nanomaterials,gold nanomaterials with tunable morphologies,easy modification,good biological safety,and radiation sensitization capability are excellent candidates for cancer theranostics.Given the superior performance of gold-based nanomaterials in biomedicine,we summary the recent advance of radionuclide labeled/doped gold-based nanomaterials for cancer theranostics.In this review article,we will discuss the methods for labelling or doping radionuclides onto gold nanomaterials,their applications for nuclear imaging and Cerenkov luminescence(CL)imaging,as well as the radioisotope therapy of cancer,and finally the toxicity evaluation of radionuclide labeled/doped gold-based nanomaterials.We hope that our review article would provide guidance for non-experts to design the radiolabeled nanomaterials for cancer imaging guided therapy.
基金supported by the Research Funds of State Key Laboratory of Pulp and Paper Engineering(No.2015C05)Science and Technology Planning Project of Guangdong,(No.2015A020215012)+1 种基金National Science Foundation of Guangdong(No.2016A030313478)Science and Technology Program of Guangzhou(No.201607010050).
文摘Volatile organic pollutants such as benzene and formaldehyde are commonly detected in the ambient air of paper mills.To remove these pollutants from the air,a photo-catalytic reactor was developed in this study.The reactor had a series of honeycomb aluminum meshes coated with nanosized titanium dioxide as the catalyst for the degradation reactions of gaseous pollutants.Both formaldehyde and benzene could be completely degraded in the reactor.However,the degrading time for benzene was much longer than that for formaldehyde,and the degradation rate of benzene decreased with increasing initial benzene concentration.It was found that the reaction pathway for formaldehyde in the mixture was different from that in its single component form,and it took about two times longer time to be degraded than that for its single component form.The reaction pathway of benzene was similar in either case although the degradation time for benzene was about 50%shorter in the mixture form.
基金supported by the Research Funds of the National Science Foundation of Guangdong,China(No.2016A030313478)State Key Laboratory of Pulp and Paper Engineering(No.2017ZD03).
文摘Photo-electro-catalytic(PEC)oxidation has been widely recognized as an effective technology for advanced treatment of papermaking wastewater.To optimize the oxidation process,it is important of monitor continuously the chemical oxygen demand(COD)of inflow and outflow wastewater.However,online COD sensors are expensive difficult to maintain,and therefore COD is usually analyzed off-line in laboratories in most cases.The objective of this study is to develop an inexpensive method for on-line COD measurement.The oxidation-reduction potential(ORP),pH,and dissolved oxygen(DO)of wastewater were selected as the key parameters,which consists of four different types of artificial neural network(ANNs)methods:multi-layer perceptron neural network(MLP),back propagation neural network(BPNN),radial basis neural network(RBNN)and generalized regression neural network(GRNN).These parameters were applied in the development of COD soft-sensing models.Six batches of papermaking wastewater with different pollution loads were treated with PEC technology over a period of 90 minutes,and a total of 546 data points was collected,including the on-line measurements of ORP,pH and DO,as well as off-line COD data.The 546 data points were divided into training set(410 data,75%of total)and validation set(136 data,25%of total).Four statistical criteria,namely,root mean square error(RMSE),mean absolute error(MAE),mean absolute relative error(MARE),and determination coefficient(R2)were used to assess the performance of the models developed with the training set of data.The comparison of results for the four ANN models for COD soft-sensing indicated that the RBNN model behaved most favorably,which possessed precise and predictable results with R2=0.913 for the validation set.Lastly,the proposed RBNN model was applied to a new batch of PEC oxidation of papermaking wastewater,and the results indicated that the model could be applied successfully for COD soft-sensing for the wastewater.