In this paper,a compact finite difference scheme for the nonlinear fractional integro-differential equation with weak singularity at the initial time is developed,with O(N^(-(2-α))+M^(-4))accuracy order,where N;M den...In this paper,a compact finite difference scheme for the nonlinear fractional integro-differential equation with weak singularity at the initial time is developed,with O(N^(-(2-α))+M^(-4))accuracy order,where N;M denote the numbers of grids in temporal and spatial direction,α ∈(0,1)is the fractional order.To recover the full accuracy based on the regularity requirement of the solution,we adopt the L1 method and the trapezoidal product integration(PI)rule with graded meshes to discretize the Caputo derivative and the Riemann-Liouville integral,respectively,further handle the nonlinear term carefully by the Newton linearized method.Based on the discrete fractional Gr¨onwall inequality and preserved discrete coefficients of Riemann-Liouville fractional integral,the stability and convergence of the proposed scheme are analyzed by the energy method.Theoretical results are also confirmed by a numerical example.展开更多
The development of novel single-atom catalysts is important for highly efficient electrochemical catalysis and sensing.In this work,a novel Pt single atoms(SAs)supported on Ni_(6)Co_(1)layered double hydroxides/nitrog...The development of novel single-atom catalysts is important for highly efficient electrochemical catalysis and sensing.In this work,a novel Pt single atoms(SAs)supported on Ni_(6)Co_(1)layered double hydroxides/nitrogen-doped graphene(Pt_(1)/Ni_(6)Co_(1)LDHs/NG)was constructed for electrochemical enzyme-free catalysis and sensing towards glucose.The loading of Pt single atoms increases with doping of Co atoms that generate more anchoring sites for Pt SAs.The resulting Pt_(1)/Ni_(6)Co_(1)LDHs/NG exhibits low oxidative potential of 0.440 V with high sensitivity of 273.78μA·mM^(−1)·cm^(−2)toward glucose,which are 85 mV lower and 15 times higher than those of Ni(OH)_(2),respectively.Pt_(1)/Ni_(6)Co_(1)LDHs/NG also shows excellent selectivity and great stability during 5-week testing.Theoretical and experimental results show that the boosted performance of Pt_(1)/Ni_(6)Co_(1)LDHs/NG originates from its stronger binding energy with glucose and the synergistic effect of Pt SAs,Co doping,and NG.This work provides a general strategy of designing highly active SACs for extending their application in electrochemical sensing.展开更多
Single-atom catalysts(SACs)are attracting extensive attention due to their incredibly catalytic activity and selectivity,high utilization of metal atoms,and obvious cost reduction.The unique ordered porous materials(O...Single-atom catalysts(SACs)are attracting extensive attention due to their incredibly catalytic activity and selectivity,high utilization of metal atoms,and obvious cost reduction.The unique ordered porous materials(OPMs)are promising carriers for stabilizing single atoms due to their large surface areas and uniformly tunable pore sizes.Meantime,the geometric and electronic structures of single-atom metals can be tuned by the interaction between the single-atoms(SAs)and OPMs to enhance the catalytic activity of SACs.The SACs based on OPMs,such as zeolites,metal-organic frameworks,and ordered mesoporous materials,have been developing fast recently.Herein,we review recent advancements on structural feature,synthetic strategy,characterization technique,and catalytic applications of OPMs-based SACs.The opportunities and challenges about SAs/OPMs are also provided to develop the novel catalysts with superior catalytic performances in the future.展开更多
Iodoacetic acid(IAA) is an unregulated disinfection byproduct in drinking water and has been shown to exert cytotoxicity, genotoxicity, tumorigenicity, and reproductive and developmental toxicity. However, the effects...Iodoacetic acid(IAA) is an unregulated disinfection byproduct in drinking water and has been shown to exert cytotoxicity, genotoxicity, tumorigenicity, and reproductive and developmental toxicity. However, the effects of IAA on gut microbiota and its metabolism are still unknown, especially the association between gut microbiota and the metabolism and toxicity of IAA. In this study, female and male Sprague–Dawley rats were exposed to IAA at 0 and 16 mg/kg bw/day daily for 8 weeks by oral gavage. Results of 16S r RNA gene sequencing showed that IAA could alter the diversity, relative abundance and function of gut microbiota in female and male rats. IAA also increased the abundance of genes related to steroid hormone biosynthesis in the gut microbiota of male rats. Moreover, metabolomics profiling revealed that IAA could significantly disturb 6 and 13 metabolites in the feces of female and male rats, respectively. In female rats, the level of androstanediol increased in the IAA treatment group. These results were consistent with our previous findings, where IAA was identified as an androgen disruptor. Additionally, the perturbed gut microbiota and altered metabolites were correlated with each other. The results of this study indicated that IAA could disturb gut microbiota and its metabolism. These changes in gut microbiota and its metabolism were associated with the reproductive and developmental toxicity of IAA.展开更多
Rhodamine-based fluorescent probe is widely used in chemical analysis, environmental analysis and life sciences area due to their excellent optical properties. Based on the thiophilic property of Hg2＋, using C = S st...Rhodamine-based fluorescent probe is widely used in chemical analysis, environmental analysis and life sciences area due to their excellent optical properties. Based on the thiophilic property of Hg2＋, using C = S structural motif as the core segment, our group have designed and synthesized three novel probes containing cinnamyl aldehyde with different substituents, exhibiting high selectivity and excellent sensitivity. The structure-property relationships of these probes have been investigated that the optical change caused by electron withdrawing effect and heavy atom effect. Furthermore, these Hg2＋ probes could be applied in living mice imaging, which provide a promising tool for quantitative mercury（Ⅱ） ion imaging in living organism.展开更多
基金supported by the National Natural Science Foundation of China(No.11701103,11801095)Young Top-notch Talent Program of Guangdong Province(No.2017GC010379)+2 种基金Natural Science Foundation of Guangdong Province(No.2022A1515012147,2019A1515010876,2017A030310538)the Project of Science and Technology of Guangzhou(No.201904010341,202102020704)the Opening Project of Guangdong Province Key Laboratory of Computational Science at the Sun Yat-sen University(2021023)。
文摘In this paper,a compact finite difference scheme for the nonlinear fractional integro-differential equation with weak singularity at the initial time is developed,with O(N^(-(2-α))+M^(-4))accuracy order,where N;M denote the numbers of grids in temporal and spatial direction,α ∈(0,1)is the fractional order.To recover the full accuracy based on the regularity requirement of the solution,we adopt the L1 method and the trapezoidal product integration(PI)rule with graded meshes to discretize the Caputo derivative and the Riemann-Liouville integral,respectively,further handle the nonlinear term carefully by the Newton linearized method.Based on the discrete fractional Gr¨onwall inequality and preserved discrete coefficients of Riemann-Liouville fractional integral,the stability and convergence of the proposed scheme are analyzed by the energy method.Theoretical results are also confirmed by a numerical example.
基金C.S.S.thanks the support from the National Natural Science Foundation of China(No.21874031)“Chu-Tian Scholar”Program of Hubei Province.M.H.Z.acknowledges the support from the NSFC of China(No.22171075)+4 种基金Guangxi Province(No.2017GXNSFDA198040)the BAGUI talent program(No.2019AC26001)J.J.L.and X.F.G.acknowledge the support by the institutional funds and New Faculty Seed Grant from ORAP at WSUThis research used resources of the Advanced Photon Source,an Office of Science User Facility operated for the U.S.Department of Energy(DOE)Office of Science by Argonne National Laboratory under Contract(No.DE-AC02-06CH11357)Y.M.Z.thanks the support from the China Postdoctoral Science Foundation(No.2021M701133).
文摘The development of novel single-atom catalysts is important for highly efficient electrochemical catalysis and sensing.In this work,a novel Pt single atoms(SAs)supported on Ni_(6)Co_(1)layered double hydroxides/nitrogen-doped graphene(Pt_(1)/Ni_(6)Co_(1)LDHs/NG)was constructed for electrochemical enzyme-free catalysis and sensing towards glucose.The loading of Pt single atoms increases with doping of Co atoms that generate more anchoring sites for Pt SAs.The resulting Pt_(1)/Ni_(6)Co_(1)LDHs/NG exhibits low oxidative potential of 0.440 V with high sensitivity of 273.78μA·mM^(−1)·cm^(−2)toward glucose,which are 85 mV lower and 15 times higher than those of Ni(OH)_(2),respectively.Pt_(1)/Ni_(6)Co_(1)LDHs/NG also shows excellent selectivity and great stability during 5-week testing.Theoretical and experimental results show that the boosted performance of Pt_(1)/Ni_(6)Co_(1)LDHs/NG originates from its stronger binding energy with glucose and the synergistic effect of Pt SAs,Co doping,and NG.This work provides a general strategy of designing highly active SACs for extending their application in electrochemical sensing.
基金“Chu-Tian Scholar”Program of Hubei ProvinceNational Natural Science Foundation of China,Grant/Award Number:21874031+3 种基金Tencent Foundation through the XPLORER PRIZEthe Beijing Natural Science Foundation,Grant/Award Number:JQ18005the Fund of the State Key Laboratory of Solidification Processing in NWPU,Grant/Award Number:SKLSP202004the National Science Fund for Distinguished Young Scholars,Grant/Award Number:52025133。
文摘Single-atom catalysts(SACs)are attracting extensive attention due to their incredibly catalytic activity and selectivity,high utilization of metal atoms,and obvious cost reduction.The unique ordered porous materials(OPMs)are promising carriers for stabilizing single atoms due to their large surface areas and uniformly tunable pore sizes.Meantime,the geometric and electronic structures of single-atom metals can be tuned by the interaction between the single-atoms(SAs)and OPMs to enhance the catalytic activity of SACs.The SACs based on OPMs,such as zeolites,metal-organic frameworks,and ordered mesoporous materials,have been developing fast recently.Herein,we review recent advancements on structural feature,synthetic strategy,characterization technique,and catalytic applications of OPMs-based SACs.The opportunities and challenges about SAs/OPMs are also provided to develop the novel catalysts with superior catalytic performances in the future.
基金supported by the National Natural Science Foundation of China (Nos. 82160603 , 81560524 , 81360421)the Guangxi Natural Science Foundation (No. 2018GXNSFAA050076)Innovation Project of Guangxi Graduate Education (No. YCSW2020123)。
文摘Iodoacetic acid(IAA) is an unregulated disinfection byproduct in drinking water and has been shown to exert cytotoxicity, genotoxicity, tumorigenicity, and reproductive and developmental toxicity. However, the effects of IAA on gut microbiota and its metabolism are still unknown, especially the association between gut microbiota and the metabolism and toxicity of IAA. In this study, female and male Sprague–Dawley rats were exposed to IAA at 0 and 16 mg/kg bw/day daily for 8 weeks by oral gavage. Results of 16S r RNA gene sequencing showed that IAA could alter the diversity, relative abundance and function of gut microbiota in female and male rats. IAA also increased the abundance of genes related to steroid hormone biosynthesis in the gut microbiota of male rats. Moreover, metabolomics profiling revealed that IAA could significantly disturb 6 and 13 metabolites in the feces of female and male rats, respectively. In female rats, the level of androstanediol increased in the IAA treatment group. These results were consistent with our previous findings, where IAA was identified as an androgen disruptor. Additionally, the perturbed gut microbiota and altered metabolites were correlated with each other. The results of this study indicated that IAA could disturb gut microbiota and its metabolism. These changes in gut microbiota and its metabolism were associated with the reproductive and developmental toxicity of IAA.
基金the National Natural Science Foundation of China (Nos. 21572177 and 21673173)the Shaanxi Provincial Natural Science Fund Project (No. 2016JZ004)the Xi’an City Science and Technology Project (No. CXY1529) for financial support
文摘Rhodamine-based fluorescent probe is widely used in chemical analysis, environmental analysis and life sciences area due to their excellent optical properties. Based on the thiophilic property of Hg2＋, using C = S structural motif as the core segment, our group have designed and synthesized three novel probes containing cinnamyl aldehyde with different substituents, exhibiting high selectivity and excellent sensitivity. The structure-property relationships of these probes have been investigated that the optical change caused by electron withdrawing effect and heavy atom effect. Furthermore, these Hg2＋ probes could be applied in living mice imaging, which provide a promising tool for quantitative mercury（Ⅱ） ion imaging in living organism.
