Viscoelastic flows play an important role in numerous engineering fields,and the multiscale algorithms for simulating viscoelastic flows have received significant attention in order to deepen our understanding of the ...Viscoelastic flows play an important role in numerous engineering fields,and the multiscale algorithms for simulating viscoelastic flows have received significant attention in order to deepen our understanding of the nonlinear dynamic behaviors of viscoelastic fluids.However,traditional grid-based multiscale methods are confined to simple viscoelastic flows with short relaxation time,and there is a lack of uniform multiscale scheme available for coupling different solvers in the simulations of viscoelastic fluids.In this paper,a universal multiscale method coupling an improved smoothed particle hydrodynamics(SPH)and multiscale universal interface(MUI)library is presented for viscoelastic flows.The proposed multiscale method builds on an improved SPH method and leverages the MUI library to facilitate the exchange of information among different solvers in the overlapping domain.We test the capability and flexibility of the presented multiscale method to deal with complex viscoelastic flows by solving different multiscale problems of viscoelastic flows.In the first example,the simulation of a viscoelastic Poiseuille flow is carried out by two coupled improved SPH methods with different spatial resolutions.The effects of exchanging different physical quantities on the numerical results in both the upper and lower domains are also investigated as well as the absolute errors in the overlapping domain.In the second example,the complex Wannier flow with different Weissenberg numbers is further simulated by two improved SPH methods and coupling the improved SPH method and the dissipative particle dynamics(DPD)method.The numerical results show that the physical quantities for viscoelastic flows obtained by the presented multiscale method are in consistence with those obtained by a single solver in the overlapping domain.Moreover,transferring different physical quantities has an important effect on the numerical results.展开更多
Multi-gram synthesis and densification is presented for a porous polymer network (PPN-4) examined as a possible vehicular methane storage material. Compaction at 17,000 psi doubled the bulk density of the material and...Multi-gram synthesis and densification is presented for a porous polymer network (PPN-4) examined as a possible vehicular methane storage material. Compaction at 17,000 psi doubled the bulk density of the material and unexpectedly increased microporosity within the material. As a result, the densified material exhibits higher excess gravimetric methane uptake and improved total volumetric methane uptake relative to the powder.展开更多
Photocatalytic aerobic oxidation reactions are largely governed by the efficiency of charge separation and subsequent reactive oxygen species(ROS) generation. Herein, we report a polarization engineering strategy to p...Photocatalytic aerobic oxidation reactions are largely governed by the efficiency of charge separation and subsequent reactive oxygen species(ROS) generation. Herein, we report a polarization engineering strategy to promote the charge separation and ROS generation efficiency by substituting the benzene unit with furan/thiophene in porous organic polymers(POPs). Benefiting from the extent of local polarization, the thiophene-containing POP(JNU-218) exhibits the best photocatalytic performance in aerobic oxidation reactions, with a yield much higher than those for the furan-containing POP(JNU-217) and the benzenecontaining POP(JNU-216). Experimental studies and theoretical calculations reveal that the increase of local polarization can indeed reduce the exciton binding energy, and therefore facilitate the separation of electron-hole pairs. This work demonstrates a viable strategy to tune charge separation and ROS generation efficiency by modulating the dipole moments of the building blocks in porous polymeric organic semiconductors.展开更多
Metabolites of algae such as geosmin, 2- methylisoborneol etc. are reported to induce pungent odors into drinking water and attract additional scientifc attention. Recently, in China, taste and odor outbreaks in drink...Metabolites of algae such as geosmin, 2- methylisoborneol etc. are reported to induce pungent odors into drinking water and attract additional scientifc attention. Recently, in China, taste and odor outbreaks in drinking water supply have become increasingly common. In source water affected by eutrophication, dimethyl trisulfide, speculated to be produced by decayed algae, was found to be the source of taste and odor issues and can be removed effectively by usual oxidation agents. In this experimental study, batch scale tests were carried out focusing on the removal of dimethyl trisulfide. Reaction kinetics of dimethyl trisulfide oxidized by potassium permanganate in water had been studied; influence factors such as pH, organic substrate, other existed taste, and odor contaminant in equivalent concentration were also dis- cussed. Results showed that dimethyl trisulfide can be removed by potassium permanganate efficiently; the ratio can reach more than 70% with oxidant dosage of 4 mg. L~ and contact time prolonged to 120 min. The dimethyl trisulfide decomposition followed a second-order kinetics pattern with a rate constant k -- 0.00213 L.（min.mg）-1. Typically, the degradation rate of dimethyl trisulfide was increased with the increasing KMnO4 dosage, but dramatically dropped with the increasing levels of humic acid （1.8-4.5 mg. L-1） and other odor-causing compounds （e.g. fl-cyclocitral, 0-1886.0 pg.L-1）. Solution pH （5.2- 9.0） and initial dimethyl trisulfide concentration did not significantly affected the degradation. This study demon- strates that KMnO4 oxidation is an effective option to remove dimethyl trisulfide from water.展开更多
Metal-organic frameworks(MOFs)are emerging as one of the most intriguing classes of heterogeneous photocatalysts owing to their abundant structures,tunable porosity,and versatile functions.The advantages of bottom-up ...Metal-organic frameworks(MOFs)are emerging as one of the most intriguing classes of heterogeneous photocatalysts owing to their abundant structures,tunable porosity,and versatile functions.The advantages of bottom-up design and reticular synthesis render MOF materials with desired photocatalytic properties for targeted reactions.In this review,we discussed the design and synthesis of MOF-based photocatalysts as well as strategies for enhancing photocatalytic performance.Recent progress on MOFs as platforms for photocatalytic aerobic oxidation reactions was summarized and categorized according to the types of bond formation.We hope this review will give an in-depth insight into MOF-based photocatalytic systems for not only aerobic oxidation reactions but also other organic transformations.A brief outlook on the challenges and opportunities of MOFs as heterogeneous photocatalysts is provided at the end of the review.展开更多
基金Project supported by the National Natural Science Foundation of China(No.52109068)the Water Conservancy Technology Project of Jiangsu Province of China(No.2022060)。
文摘Viscoelastic flows play an important role in numerous engineering fields,and the multiscale algorithms for simulating viscoelastic flows have received significant attention in order to deepen our understanding of the nonlinear dynamic behaviors of viscoelastic fluids.However,traditional grid-based multiscale methods are confined to simple viscoelastic flows with short relaxation time,and there is a lack of uniform multiscale scheme available for coupling different solvers in the simulations of viscoelastic fluids.In this paper,a universal multiscale method coupling an improved smoothed particle hydrodynamics(SPH)and multiscale universal interface(MUI)library is presented for viscoelastic flows.The proposed multiscale method builds on an improved SPH method and leverages the MUI library to facilitate the exchange of information among different solvers in the overlapping domain.We test the capability and flexibility of the presented multiscale method to deal with complex viscoelastic flows by solving different multiscale problems of viscoelastic flows.In the first example,the simulation of a viscoelastic Poiseuille flow is carried out by two coupled improved SPH methods with different spatial resolutions.The effects of exchanging different physical quantities on the numerical results in both the upper and lower domains are also investigated as well as the absolute errors in the overlapping domain.In the second example,the complex Wannier flow with different Weissenberg numbers is further simulated by two improved SPH methods and coupling the improved SPH method and the dissipative particle dynamics(DPD)method.The numerical results show that the physical quantities for viscoelastic flows obtained by the presented multiscale method are in consistence with those obtained by a single solver in the overlapping domain.Moreover,transferring different physical quantities has an important effect on the numerical results.
文摘Multi-gram synthesis and densification is presented for a porous polymer network (PPN-4) examined as a possible vehicular methane storage material. Compaction at 17,000 psi doubled the bulk density of the material and unexpectedly increased microporosity within the material. As a result, the densified material exhibits higher excess gravimetric methane uptake and improved total volumetric methane uptake relative to the powder.
基金supported by the National Natural Science Foundation of China (22275073,22005119,21731002,21975104 and 22150004)Guangdong Major Project of Basic and Applied Research (2019B030302009)+2 种基金Guangdong Basic and Applied Basic Research Foundation (2020A1515110404)Guangzhou Basic and Applied Basic Research Foundation (202102020444)the Fundamental Research Funds for the Central Universities (21622409)。
基金supported by the National Natural Science Foundation of China(21731002,21975104,22101099,22150004,22271120)Guangdong Major Project of Basic and Applied Research(2019B030302009)+1 种基金the Outstanding Innovative Talents Cultivation Funded Programs for Doctoral Students of Jinan University(2022CXB007)the Fundamental Research Funds for the Central Universities and Jinan University(21621035)。
文摘Photocatalytic aerobic oxidation reactions are largely governed by the efficiency of charge separation and subsequent reactive oxygen species(ROS) generation. Herein, we report a polarization engineering strategy to promote the charge separation and ROS generation efficiency by substituting the benzene unit with furan/thiophene in porous organic polymers(POPs). Benefiting from the extent of local polarization, the thiophene-containing POP(JNU-218) exhibits the best photocatalytic performance in aerobic oxidation reactions, with a yield much higher than those for the furan-containing POP(JNU-217) and the benzenecontaining POP(JNU-216). Experimental studies and theoretical calculations reveal that the increase of local polarization can indeed reduce the exciton binding energy, and therefore facilitate the separation of electron-hole pairs. This work demonstrates a viable strategy to tune charge separation and ROS generation efficiency by modulating the dipole moments of the building blocks in porous polymeric organic semiconductors.
文摘Metabolites of algae such as geosmin, 2- methylisoborneol etc. are reported to induce pungent odors into drinking water and attract additional scientifc attention. Recently, in China, taste and odor outbreaks in drinking water supply have become increasingly common. In source water affected by eutrophication, dimethyl trisulfide, speculated to be produced by decayed algae, was found to be the source of taste and odor issues and can be removed effectively by usual oxidation agents. In this experimental study, batch scale tests were carried out focusing on the removal of dimethyl trisulfide. Reaction kinetics of dimethyl trisulfide oxidized by potassium permanganate in water had been studied; influence factors such as pH, organic substrate, other existed taste, and odor contaminant in equivalent concentration were also dis- cussed. Results showed that dimethyl trisulfide can be removed by potassium permanganate efficiently; the ratio can reach more than 70% with oxidant dosage of 4 mg. L~ and contact time prolonged to 120 min. The dimethyl trisulfide decomposition followed a second-order kinetics pattern with a rate constant k -- 0.00213 L.（min.mg）-1. Typically, the degradation rate of dimethyl trisulfide was increased with the increasing KMnO4 dosage, but dramatically dropped with the increasing levels of humic acid （1.8-4.5 mg. L-1） and other odor-causing compounds （e.g. fl-cyclocitral, 0-1886.0 pg.L-1）. Solution pH （5.2- 9.0） and initial dimethyl trisulfide concentration did not significantly affected the degradation. This study demon- strates that KMnO4 oxidation is an effective option to remove dimethyl trisulfide from water.
基金supported by the National Natural Science Foundation of China(21731002,21975104,22101099,22150004,22271120)Guangdong Major Project of Basic and Applied Research(2019B030302009)the Outstanding Innovative Talents Cultivation Funded Programs for Doctoral Students of Jinan University(2022CXB007)。
文摘Metal-organic frameworks(MOFs)are emerging as one of the most intriguing classes of heterogeneous photocatalysts owing to their abundant structures,tunable porosity,and versatile functions.The advantages of bottom-up design and reticular synthesis render MOF materials with desired photocatalytic properties for targeted reactions.In this review,we discussed the design and synthesis of MOF-based photocatalysts as well as strategies for enhancing photocatalytic performance.Recent progress on MOFs as platforms for photocatalytic aerobic oxidation reactions was summarized and categorized according to the types of bond formation.We hope this review will give an in-depth insight into MOF-based photocatalytic systems for not only aerobic oxidation reactions but also other organic transformations.A brief outlook on the challenges and opportunities of MOFs as heterogeneous photocatalysts is provided at the end of the review.
