We introduced bipyridine ligands into a series of two‐dimensional (2D) covalent organic frame‐works (COFs) using 2,2’‐bipyridine‐5,5’‐dicarbaldehyde (2,2’‐BPyDCA) as a component in the mixed building bl...We introduced bipyridine ligands into a series of two‐dimensional (2D) covalent organic frame‐works (COFs) using 2,2’‐bipyridine‐5,5’‐dicarbaldehyde (2,2’‐BPyDCA) as a component in the mixed building blocks. The framework of the COFs was formed by the linkage of imine groups. The ligand content in the COFs was synthetically tuned by the content of 2,2’‐BPyDCA, and thus the amount of metal, palladium(II) acetate, bonded to the nitrogen ligands could be manipulated. Both the bipyri‐dine ligands and imine groups can coordinate with Pd(II) ions, but the loading position can be var‐ied, with one ligand favoring binding in the space between adjacent COFs’ layers and the other lig‐and favoring binding within the pores of the COFs. The Pd(II)‐loaded COFs exhibited good catalytic activity for the Heck reaction.展开更多
First-row transition metal compounds have been widely explored as oxygen evolution reaction(OER)electrocatalysts due to their impressive performance in this application.However,the activity trends of these electrocata...First-row transition metal compounds have been widely explored as oxygen evolution reaction(OER)electrocatalysts due to their impressive performance in this application.However,the activity trends of these electrocatalysts remain elusive due to the effect of inevitable iron impurities in alkaline electrolytes on the OER;the inhomogeneous structure of iron-based(oxy)hydroxides further complicates this situation.Bimetallic metal-organic frameworks(MOFs)have the advantages of well-defined and uniform atomic structures and the tunable coordination environments,allowing the structure-activity relationships of bimetallic sites to be precisely explored.Therefore,we prepared a series of iron-based bimetallic MOFs(denoted as Fe_(2)M-MIL-88B,M=Mn,Co,or Ni)and systematically compared their electrocatalytic performance in the OER in this work.All the bimetallic MOFs exhibited higher OER activity than their monometallic iron-based counterpart,with their activity following the order FeNi>FeCo>FeMn.In an alkaline electrolyte,Fe2Ni-MIL-88B showed the lowest overpotential to achieve a current density of 10 mA cm^(–2)(307 mV)and the smallest Tafel slope(38 mV dec^(–1)).The experimental and calculated results demonstrated that iron and nickel exhibited the strongest coupling effect in the series,leading to modification of the electronic structure,which is crucial for tuning the electrocatalytic activity.展开更多
Oxygen evolution from water driven by electrocatalysis or photocatalysis poses a significant challenge as it requires the use of efficient electro-/photo-catalysts to drive the four-electron oxygen evolution reaction(...Oxygen evolution from water driven by electrocatalysis or photocatalysis poses a significant challenge as it requires the use of efficient electro-/photo-catalysts to drive the four-electron oxygen evolution reaction(OER).Herein,we report the development of an effective strategy for the in situ chemical transformation of Fe-based bimetallic MIL-88 metal-organic frameworks(MOFs)into corresponding bimetallic hydroxides,which are composed of amorphous ultrasmall nanoparticles and afford an abundance of catalytically active sites.Optimized MOF-derived NiFe-OH-0.75 catalyst coated on glassy carbon electrodes achieved a current density of 10 mA cm^(-2)in the electrocatalytic OER with a small overpotential of 270 mV,which could be decreased to 235 mV when loading the catalysts on a nickel foam substrate.Moreover,these MOF-derived Fe-based bimetallic hydroxides can be used as efficient cocatalysts when combined with suitable photosensitizers for photocatalytic water oxidation.展开更多
Hydrogen evolution reaction is a critical reaction in water splitting for hydrogen production.However,developing effective and stable non‐noble‐metal electrocatalysts which work well at high current densities demand...Hydrogen evolution reaction is a critical reaction in water splitting for hydrogen production.However,developing effective and stable non‐noble‐metal electrocatalysts which work well at high current densities demanded by industry still remain great challenge.Herein,taking advantage of the highly tunable metal‐organic framework(MOF)templates,nitrogen doped binary transition metal phosphides electrocatalysts(N‐CoP_(x)/Ni_(2)P)with three‐dimensional(3D)conductive network structure were successfully synthesized.The 3D open porous channels could expose more catalytically active sites;nitrogen doping and the synergistic effect between CoP and Ni_(2)P can increase the electron density of Co atoms at active sites,further optimizing the Gibbs free energy of hydrogen(ΔGH*)and water(ΔG_(H_(2)O*)).As a result,the obtained N‐CoP_(x)/Ni_(2)P catalyst exhibits extraordinary electrocatalytic activity in a wide pH range.Especially,it requires an extremely low overpotential of 152 mV to deliver a high current density of 650 mA cm^(–2) in alkaline media.This work may shed some light on the rational design of cheap electrocatalysts and electrode materials that work well at high current densities.展开更多
Cobalt-based nanomaterials have been intensively explored as one of the most promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. However, most of their performances are still inferior to state...Cobalt-based nanomaterials have been intensively explored as one of the most promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. However, most of their performances are still inferior to state-of-the-art precious metals especially for Ru and Ir.Herein, we apply a continuous ion exchange method and further hydrothermal treatment to synthesize the flake-like Ag-CoSO4 nanohybrids beginning from Co-BTC (BTC:benzene-1,3,5-tricarboxylic acid) metal-organic frameworks precursor. The catalyst exhibits superior OER performance under the alkaline electrolyte solution (a low overpotential of 282 mV at 10 mA/cm2 in 1 mol/L KOH), which is even better than RuO2 due to the improved conductivity and rapid electrons transfer process via introducing small amount of Ag. The existence of Ag in the hybrids is beneficial for increasing the Co(IV) concentration, thus promoting the *OOH intermediate formation process. Besides, due to the very low requirement of Ag content (lower than 1 atom%), the cost of the catalyst is also limited. This work provides a new insight for designing of inexpensive OER catalysts with high performance and low cost.展开更多
The development of high efficiency and stable electrocatalysts for oxygen evolution is critical for energy storage and conversion systems. Herein, a series of Co/Fe bimetal-organic frameworks (MOFs) were fabricated us...The development of high efficiency and stable electrocatalysts for oxygen evolution is critical for energy storage and conversion systems. Herein, a series of Co/Fe bimetal-organic frameworks (MOFs) were fabricated using a facile ultrasonic method at room temperature, as electrocatalysts for the oxygen evolution reaction (OER) in alkaline solution. The Co2Fe-MOF exhibited an overpotential of 280 mV at a current density of 10 mA cm^-2, a low Tafel slope of 44.7 mV dec^-1, and long-term stability over 12000 s in 1 mol L^-1 KOH. This impressive performance was attributed to the high charge transfer rate, large specific surface area, and synergistic effects of the cobalt and iron centers.展开更多
Message framing has been shown to influence the persuasiveness of health communications. In this conceptual paper, the authors suggest that message framing can be extended to include causal attributions, and Weiner's...Message framing has been shown to influence the persuasiveness of health communications. In this conceptual paper, the authors suggest that message framing can be extended to include causal attributions, and Weiner's Attribution Theory (Weiner's AT) is an appropriate theoretical framework for the study of message framing and health communications. Weiner's AT proposes a specific motivational sequence that may explain cognitive, emotional, and behavioral responses to message frames. Propositions regarding relationships between message frames, causal attributions, and emotional and behavioral responses are presented to guide future research. The implications of this attribution-based message-framing process for future research are discussed展开更多
This paper describes the characteristics of the supply chain e-commerce era, understands the concept,content and objectives of supply chain management,and raises supply chain management model,and also analyzes e-comme...This paper describes the characteristics of the supply chain e-commerce era, understands the concept,content and objectives of supply chain management,and raises supply chain management model,and also analyzes e-commerce supply chain architecture.On the existing architecture,elaborates the build about e-commerce supply chain management system, along with proposing strategic directions of e-commerce supply chain management,including JIT, quick response, efficient customer response, enterprise resource planning and electronic ordering system,and discusses in detail the effects of various policy for the entire e-commerce supply chain management.展开更多
Free will is difficult to classify with respect to determinism or indeterminism, and its phenomenology in consciousness often shows both aspects. Initially, it is felt as unlimited and indeterminate will power, with t...Free will is difficult to classify with respect to determinism or indeterminism, and its phenomenology in consciousness often shows both aspects. Initially, it is felt as unlimited and indeterminate will power, with the potentiality of multiple choices. Thereafter, reductive deliberation is led by determinism to the final decision, which realises only one of the potential choices. The reductive deliberation phase tries to find out the best alternative and simultaneously satisfying vague motivations, contextual conditions and personal preferences. The essential sense of free will is the introduction of personal preferences, which allows a higher diversity of reactions to vague motivations. With an oversimplified model of determinism as a chain of events, incompatibilists define "free" as "undetermined" so that determinism becomes incompatible with any free choice between alternatives. In consciousness, free will requires a more complex model of network determinism as well as the consideration of unconsciousness as a causal factor. When "free" defined as "undetermined" is applied to the context of consciousness, it should be reinterpreted as "unconscious of being determined" or not aware of underlying determinism. Lacking information on determinism generates a feeling of "free" in consciousness and, therefore, gives the impression of indeterminism. Lacking information may be induced by an uncertain future without determined events--an unconscious past with biological reactions suddenly emerging from the unconsciousness or an unknown present unable to distinguish determinism of complex events. Therefore, at the level of human consciousness, the experience of free will is associated with apparent indeterminism although it is based on unconscious determinism. The concepts of compatibilism and incompatibilism are only two different aspects of the same phenomenon and correspond to consciousness and unconsciousness. Nevertheless, they can be considered together with a free will concept based on relativity depending on two different reference frames--the first person's experience frame or the Laplace's demon frame with knowledge on every molecule of the universe. Only relativity of the free will concept avoids the contradiction between "free" and "unfree" for the same phenomenon and could be a compromise for considering compatibilism and incompatibilism equally.展开更多
The catalytic hydrogenation of halonitroarenes to haloanilines is a green and sustainable process for the production of key nitrogen-containing intermediates in fine chemical industry.Chemoselective hydrogenation pose...The catalytic hydrogenation of halonitroarenes to haloanilines is a green and sustainable process for the production of key nitrogen-containing intermediates in fine chemical industry.Chemoselective hydrogenation poses a significant challenge,which requires the rational design of the catalysts with proper hydrogenation ability for nitro group and simultaneously preventing dehalogenation of halogen group.Herein,a highly effective Rh@Al_(2)O_(3)@C single-atom catalyst(SAC)was developed for the hydrogenation of m-chloronitrobenzene(m-CNB)to m-chloroaniline(m-CAN),through an in-situ grafting of metal during the assembly of MIL-53(Al),followed by confined pyrolysis.Extensive characterizations reveal an exquisite structure of the Rh@Al_(2)O_(3)@C,containing atomically dispersed Rh sites onto Al_(2)O_(3) confined by the amorphous carbon.The five-coordinated aluminum(Al^(Ⅴ))species are essential for achieving the atomic dispersion of Rh atoms,providing the unsaturated coordinative sites for metal.Compared to the benchmark Rh/γ-Al_(2)O_(3) and Rh/C nanocatalysts,the Rh@Al_(2)O_(3)@C SAC affords an excellent turnover frequency of 2317 molm-CNB·molRh^(–1)·h^(–1),the highest value to date in heterogeneous catalyst systems for the hydrogenation of m-CNB at 313 K and 20 bar H2,together with a sustained selectivity to m-CAN(~98%)during five consecutive runs.The superior catalytic performance of the Rh@Al_(2)O_(3)@C is attributed to a proper modulation of electronic structure of hydrogenation metal by forming SAC,together with an enhanced accessibility of acid function sites.展开更多
Molecular catalysts for H2-evolution are of interest for their integration into light-harvesting complexes for photocatalytic water splitting.Here,we report the meso-tetra(4-carboxyphenyl)porphine[(TCPP)Pt^(Ⅱ)]comple...Molecular catalysts for H2-evolution are of interest for their integration into light-harvesting complexes for photocatalytic water splitting.Here,we report the meso-tetra(4-carboxyphenyl)porphine[(TCPP)Pt^(Ⅱ)]complex as a molecular H2-evolving photocatalyst using chloranilic acid(CA)as a sacrificial electron donor,the choice of which is critical to the stability of the photocatalyst.When triethanolamine was used,[(TCPP)Pt^(Ⅱ)]decomposed to form Pt nanoparticles.Density functional theory calculations together with evidence from electrochemical and spectroscopic analyses suggested that the catalysis was possibly initiated by a proton-coupled electron transfer(PCET)to form[(TCPP)Pt^(Ⅰ)]-N-H,followed by another electron injection and protonation to form a[(TCPP)Pt^(Ⅱ)-hydride]-N-H intermediate that can release H2.As the whole catalytic cycle involves the injection of multiple electrons,a light-harvesting network should be helpful by providing multiple photo-induced electrons.Thus,we integrated this molecular catalyst into a light-harvesting metal-organic framework to boost its activity by~830 times.This work presents a mechanistic study of the photocatalytic H2 evolution and energy transfer and highlights the importance of a light-harvesting network for multiple electron injections.展开更多
The present paper addresses the subject of truss damage identification using measured frequency response functions (FRF). Damage identification matrix is formed using measured FRFs obtained from truss dynamic test. Th...The present paper addresses the subject of truss damage identification using measured frequency response functions (FRF). Damage identification matrix is formed using measured FRFs obtained from truss dynamic test. Then using principal component analysis (PCA),the variable space dimensions of damage identification matrix can be reduced,and original data characters of FRFs can be analyzed and extracted from lower dimension variable space. Thus truss damages can be identified using the multivariate control chart of first several order principal components which contain almost all of original data information. Without the need for modal parameters,the method avoids the errors of modal fitting. In order to validate the reliability of the method,a whole size truss was tested with six types of damage case concerning single or two element damages. The experimental result shows that the proposed method is straightforward and reliable for truss damage identification. Especially,the method has good applicability for the truss under noisy environment and non-linear cases.展开更多
AIM:To identify differentially expressed genes in quiescent and activated hepatic stellate cells(HSCs)and explore their functions.METHODS:HSCs were isolated from the normal Sprague Dawley rats by in suit perfusion of ...AIM:To identify differentially expressed genes in quiescent and activated hepatic stellate cells(HSCs)and explore their functions.METHODS:HSCs were isolated from the normal Sprague Dawley rats by in suit perfusion of collagenase and pronase and density Nycodenz gradient centrifugation.Total RNA and mRNA of quiescent HSCs,and cultureactivated HSCs were extracted,quantified and reversely transcripted into cDNA.The global gene expression profile was analyzed by microarray with Affymetrix rat genechip.Differentially expressed genes were annotated with Gene Ontology(GO)and analyzed with Kyoto encyclopedia of genes and genomes(KEGG)pathway using the Database for Annotation,Visualization and Integrated Discovery.Microarray data were validated by quantitative real-time polymerase chain reaction(qRTPCR).The function of Wnt5a on human HSCs line LX-2 was assessed with lentivirus-mediated Wnt5a RNAi.The expression of Wnt5a in fibrotic liver of a carbon tetrachloride(CCl4)-induced fibrosis rat model was also analyzed with Western blotting.RESULTS:Of the 28 700 genes represented on this chip,2566 genes displayed at least a 2-fold increase or decrease in expression at a P<0.01 level with a false discovery rate.Of these,1396 genes were upregulated,while 1170 genes were downregulated in culture-activated HSCs.These differentially expressed transcripts were grouped into 545 GO based on biological process GO terms.The most enriched GO terms included response to wounding,wound healing,regulation of cell growth,vasculature development and actin cytoskeleton organization.KEGG pathway analysis revealed that Wnt5a signaling pathway participated in the activation of HSCs.Wnt5a was significantly increased in cultureactivated HSCs as compared with quiescent HSCs.qRTPCR validated the microarray data.Lentivirus-mediated suppression of Wnt5a expression in activated LX-2 resulted in significantly impaired proliferation,downregulated expressions of typeⅠcollagen and transforming growth factor-β1.Wnt5a was upregulated in the fibrotic liver of a CCl4-induced fibrosis rat model.CONCLUSION:Wnt5a is involved in the activation of HSCs,and it may serve as a novel therapeutic target in the treatment of liver fibrosis.展开更多
Developing highly active and durable electrocatalysts for the oxygen reduction reaction (ORR) is crucial to large-scale commercialization of fuel cells and metal-air batteries. Here we report a facile approach for t...Developing highly active and durable electrocatalysts for the oxygen reduction reaction (ORR) is crucial to large-scale commercialization of fuel cells and metal-air batteries. Here we report a facile approach for the synthesis of nitrogen and oxygen dual-doped meso-porous layer-structured carbon electrocatalyst embedded with graphitic carbon coated cobalt nanoparticles by direct pyrolysis of a layer-structured metal-organic framework. The elec- trocatalyst prepared at 800℃ exhibits comparable ORR performance to Pt/C catalysts but possesses superior stability to Pt/C catalysts. This synthetic approach provides new prospects in developing sustainable carbon-based electrocatalysts for electrochemical energy conversion devices.展开更多
Inorganic polymers are a novel class of materials formed by the polymerization of silicon, aluminium and oxygen species to form an amorphous three-dimensional framework structure. The basis of this process is the alka...Inorganic polymers are a novel class of materials formed by the polymerization of silicon, aluminium and oxygen species to form an amorphous three-dimensional framework structure. The basis of this process is the alkaline solutions to induce a certain amount of Si and AI atoms to dissolve from a feedstock such as aluminosilicate. A study of 27A1 MAS-NMR was carried out in an attempt to understand the reaction mechanism of the inorganic polymerization at ambient temperature. Scanning electron microscopy (SEM) and X-ray diflYactometry (XRD) were also employed to establish the composition and microstructure of the inorganic polymerization. Specimens were prepared with different A1/Si mole ratios from the starting materials. The higher the AI content, the more sufficient the AI atoms that can combine with SiO4, and the longer the reaction time, the more the bonded Si--O--A1--O polymer structure, and then the higher the A1 content, the fewer the octahedral A1 with a uniform Si--O--A1--O structure in four directions, because four AI atoms are combined with SiO4, resulting in a uniform Si--O--AI--O structure in four directions. The results show that they have an amorphous microstructure.展开更多
Objective To investigate the effect of Furongtongmai capsule on the in-stent restenosis (ISR) of superficial femoral artery after interventional operation in lower extremity Arteriosclerosis Occlusion (ASO)....Objective To investigate the effect of Furongtongmai capsule on the in-stent restenosis (ISR) of superficial femoral artery after interventional operation in lower extremity Arteriosclerosis Occlusion (ASO). Methods: A total of 110 inpatients with ASO who performed Superficial femoral artery stent implantation were randomly divided into observation group and control group, with 55 cases in each group.Both groups received Aspirin 100 mg/d and Clopidogrel 75 mg/d. The observation group was given Furongtongmai capsule on the basis of routine treatment. After continuous treatment for 6 months, the clinical efficacy, Ankle Brachial Index (ABI), high-sensitivity C-reactive protein (Hs-CPR) and ISR were compared between the two groups. Results: At 6 months after operation, the plasma levels of Hs-CRP in the two groups were significantly lower than those in the control group (P 〈 0.05). The ABI of treatment group was significantly higher than the control group (P 〈 0.05). There was a statistically significant difference in ISR incidence between the treatment group and the control group 6 months after surgery (9.09% vs 27.78%, P 〈 0.05). Conclusion: Furongtongmai Capsule can inhibit Hs-CRP in patients with ASO after femoral artery intervention, improve the ankle brachial index and reduce the incidence of ISR.展开更多
In our synthetic studies toward huperzine A, a diastereoselective α'-alkylation of the α-amido-γ-methyl hexenone 4 was real- ized through a dianion intermediate which significantly enhanced the reactivity. Under t...In our synthetic studies toward huperzine A, a diastereoselective α'-alkylation of the α-amido-γ-methyl hexenone 4 was real- ized through a dianion intermediate which significantly enhanced the reactivity. Under the attempted Heck reaction conditions, an unexpected and unprecedented palladium-catalyzed intramolecular T-arylation of 3 was observed, which generated 18 with bicyclo[3.3, l]nonane framework in satisfactory yield.展开更多
Metal-organic framework MIL-53(Al) was synthesized by a solvothermal method using aluminum nitrate as the aluminium source and 1,4-benzenedicarboxylic acid(H2BDC) as the organic ligand. The structure of samples was ch...Metal-organic framework MIL-53(Al) was synthesized by a solvothermal method using aluminum nitrate as the aluminium source and 1,4-benzenedicarboxylic acid(H2BDC) as the organic ligand. The structure of samples was characterized by X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR). The catalytic activity and recyclability of MIL-53(Al) catalyst for the Friedel-Crafts acylation reaction of indole with benzoyl chloride were evaluated. The reaction conditions were optimized and a reaction mechanism was suggested. The results showed that the MIL-53(Al) catalyst exhibited good catalytic activity and recyclability for the Friedel-Crafts acylation reaction. When the molar ratio of indole and MIL-53(Al) catalyst was 1:0.06(n1:ncatalyst), the molar ratio of indole and benzoyl chloride was 1:3, and the solvent was dichloromethane, the conversion of indole could reach 97.1% and the selectivity of 3-acylindole could reach 81.1% at 25 °C after 8 h. The catalyst can be reused without significant degradation in catalytic activity. After the catalyst was reused five times, the conversion of indole was 87.6% and the selectivity of 3-acylindole was 79.5%.展开更多
基金supported by the National Natural Science Foundation of China(21473196,21403214)the 100‐Talents Program of Chinese Academy of SciencesState Key Laboratory of Fine Chemicals,Dalian University of Technology(KF1415)~~
文摘We introduced bipyridine ligands into a series of two‐dimensional (2D) covalent organic frame‐works (COFs) using 2,2’‐bipyridine‐5,5’‐dicarbaldehyde (2,2’‐BPyDCA) as a component in the mixed building blocks. The framework of the COFs was formed by the linkage of imine groups. The ligand content in the COFs was synthetically tuned by the content of 2,2’‐BPyDCA, and thus the amount of metal, palladium(II) acetate, bonded to the nitrogen ligands could be manipulated. Both the bipyri‐dine ligands and imine groups can coordinate with Pd(II) ions, but the loading position can be var‐ied, with one ligand favoring binding in the space between adjacent COFs’ layers and the other lig‐and favoring binding within the pores of the COFs. The Pd(II)‐loaded COFs exhibited good catalytic activity for the Heck reaction.
文摘First-row transition metal compounds have been widely explored as oxygen evolution reaction(OER)electrocatalysts due to their impressive performance in this application.However,the activity trends of these electrocatalysts remain elusive due to the effect of inevitable iron impurities in alkaline electrolytes on the OER;the inhomogeneous structure of iron-based(oxy)hydroxides further complicates this situation.Bimetallic metal-organic frameworks(MOFs)have the advantages of well-defined and uniform atomic structures and the tunable coordination environments,allowing the structure-activity relationships of bimetallic sites to be precisely explored.Therefore,we prepared a series of iron-based bimetallic MOFs(denoted as Fe_(2)M-MIL-88B,M=Mn,Co,or Ni)and systematically compared their electrocatalytic performance in the OER in this work.All the bimetallic MOFs exhibited higher OER activity than their monometallic iron-based counterpart,with their activity following the order FeNi>FeCo>FeMn.In an alkaline electrolyte,Fe2Ni-MIL-88B showed the lowest overpotential to achieve a current density of 10 mA cm^(–2)(307 mV)and the smallest Tafel slope(38 mV dec^(–1)).The experimental and calculated results demonstrated that iron and nickel exhibited the strongest coupling effect in the series,leading to modification of the electronic structure,which is crucial for tuning the electrocatalytic activity.
文摘Oxygen evolution from water driven by electrocatalysis or photocatalysis poses a significant challenge as it requires the use of efficient electro-/photo-catalysts to drive the four-electron oxygen evolution reaction(OER).Herein,we report the development of an effective strategy for the in situ chemical transformation of Fe-based bimetallic MIL-88 metal-organic frameworks(MOFs)into corresponding bimetallic hydroxides,which are composed of amorphous ultrasmall nanoparticles and afford an abundance of catalytically active sites.Optimized MOF-derived NiFe-OH-0.75 catalyst coated on glassy carbon electrodes achieved a current density of 10 mA cm^(-2)in the electrocatalytic OER with a small overpotential of 270 mV,which could be decreased to 235 mV when loading the catalysts on a nickel foam substrate.Moreover,these MOF-derived Fe-based bimetallic hydroxides can be used as efficient cocatalysts when combined with suitable photosensitizers for photocatalytic water oxidation.
文摘Hydrogen evolution reaction is a critical reaction in water splitting for hydrogen production.However,developing effective and stable non‐noble‐metal electrocatalysts which work well at high current densities demanded by industry still remain great challenge.Herein,taking advantage of the highly tunable metal‐organic framework(MOF)templates,nitrogen doped binary transition metal phosphides electrocatalysts(N‐CoP_(x)/Ni_(2)P)with three‐dimensional(3D)conductive network structure were successfully synthesized.The 3D open porous channels could expose more catalytically active sites;nitrogen doping and the synergistic effect between CoP and Ni_(2)P can increase the electron density of Co atoms at active sites,further optimizing the Gibbs free energy of hydrogen(ΔGH*)and water(ΔG_(H_(2)O*)).As a result,the obtained N‐CoP_(x)/Ni_(2)P catalyst exhibits extraordinary electrocatalytic activity in a wide pH range.Especially,it requires an extremely low overpotential of 152 mV to deliver a high current density of 650 mA cm^(–2) in alkaline media.This work may shed some light on the rational design of cheap electrocatalysts and electrode materials that work well at high current densities.
基金supported by the National Natural Science Foundation(No.21271163,No.1232211,No.21571168)the Fundamental Research Funds for the Central Universities(WK2060140021)the CAS/SAFEA International Partnership Program for Creative Research Teams and the Hefei Science Center CAS(2016HSC-IU011)
文摘Cobalt-based nanomaterials have been intensively explored as one of the most promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. However, most of their performances are still inferior to state-of-the-art precious metals especially for Ru and Ir.Herein, we apply a continuous ion exchange method and further hydrothermal treatment to synthesize the flake-like Ag-CoSO4 nanohybrids beginning from Co-BTC (BTC:benzene-1,3,5-tricarboxylic acid) metal-organic frameworks precursor. The catalyst exhibits superior OER performance under the alkaline electrolyte solution (a low overpotential of 282 mV at 10 mA/cm2 in 1 mol/L KOH), which is even better than RuO2 due to the improved conductivity and rapid electrons transfer process via introducing small amount of Ag. The existence of Ag in the hybrids is beneficial for increasing the Co(IV) concentration, thus promoting the *OOH intermediate formation process. Besides, due to the very low requirement of Ag content (lower than 1 atom%), the cost of the catalyst is also limited. This work provides a new insight for designing of inexpensive OER catalysts with high performance and low cost.
基金supported by the National Natural Science Foundation of China(21872016)the Fundamental Research Funds for the Central Universities(DUT17ZD204)~~
文摘The development of high efficiency and stable electrocatalysts for oxygen evolution is critical for energy storage and conversion systems. Herein, a series of Co/Fe bimetal-organic frameworks (MOFs) were fabricated using a facile ultrasonic method at room temperature, as electrocatalysts for the oxygen evolution reaction (OER) in alkaline solution. The Co2Fe-MOF exhibited an overpotential of 280 mV at a current density of 10 mA cm^-2, a low Tafel slope of 44.7 mV dec^-1, and long-term stability over 12000 s in 1 mol L^-1 KOH. This impressive performance was attributed to the high charge transfer rate, large specific surface area, and synergistic effects of the cobalt and iron centers.
文摘Message framing has been shown to influence the persuasiveness of health communications. In this conceptual paper, the authors suggest that message framing can be extended to include causal attributions, and Weiner's Attribution Theory (Weiner's AT) is an appropriate theoretical framework for the study of message framing and health communications. Weiner's AT proposes a specific motivational sequence that may explain cognitive, emotional, and behavioral responses to message frames. Propositions regarding relationships between message frames, causal attributions, and emotional and behavioral responses are presented to guide future research. The implications of this attribution-based message-framing process for future research are discussed
文摘This paper describes the characteristics of the supply chain e-commerce era, understands the concept,content and objectives of supply chain management,and raises supply chain management model,and also analyzes e-commerce supply chain architecture.On the existing architecture,elaborates the build about e-commerce supply chain management system, along with proposing strategic directions of e-commerce supply chain management,including JIT, quick response, efficient customer response, enterprise resource planning and electronic ordering system,and discusses in detail the effects of various policy for the entire e-commerce supply chain management.
文摘Free will is difficult to classify with respect to determinism or indeterminism, and its phenomenology in consciousness often shows both aspects. Initially, it is felt as unlimited and indeterminate will power, with the potentiality of multiple choices. Thereafter, reductive deliberation is led by determinism to the final decision, which realises only one of the potential choices. The reductive deliberation phase tries to find out the best alternative and simultaneously satisfying vague motivations, contextual conditions and personal preferences. The essential sense of free will is the introduction of personal preferences, which allows a higher diversity of reactions to vague motivations. With an oversimplified model of determinism as a chain of events, incompatibilists define "free" as "undetermined" so that determinism becomes incompatible with any free choice between alternatives. In consciousness, free will requires a more complex model of network determinism as well as the consideration of unconsciousness as a causal factor. When "free" defined as "undetermined" is applied to the context of consciousness, it should be reinterpreted as "unconscious of being determined" or not aware of underlying determinism. Lacking information on determinism generates a feeling of "free" in consciousness and, therefore, gives the impression of indeterminism. Lacking information may be induced by an uncertain future without determined events--an unconscious past with biological reactions suddenly emerging from the unconsciousness or an unknown present unable to distinguish determinism of complex events. Therefore, at the level of human consciousness, the experience of free will is associated with apparent indeterminism although it is based on unconscious determinism. The concepts of compatibilism and incompatibilism are only two different aspects of the same phenomenon and correspond to consciousness and unconsciousness. Nevertheless, they can be considered together with a free will concept based on relativity depending on two different reference frames--the first person's experience frame or the Laplace's demon frame with knowledge on every molecule of the universe. Only relativity of the free will concept avoids the contradiction between "free" and "unfree" for the same phenomenon and could be a compromise for considering compatibilism and incompatibilism equally.
文摘The catalytic hydrogenation of halonitroarenes to haloanilines is a green and sustainable process for the production of key nitrogen-containing intermediates in fine chemical industry.Chemoselective hydrogenation poses a significant challenge,which requires the rational design of the catalysts with proper hydrogenation ability for nitro group and simultaneously preventing dehalogenation of halogen group.Herein,a highly effective Rh@Al_(2)O_(3)@C single-atom catalyst(SAC)was developed for the hydrogenation of m-chloronitrobenzene(m-CNB)to m-chloroaniline(m-CAN),through an in-situ grafting of metal during the assembly of MIL-53(Al),followed by confined pyrolysis.Extensive characterizations reveal an exquisite structure of the Rh@Al_(2)O_(3)@C,containing atomically dispersed Rh sites onto Al_(2)O_(3) confined by the amorphous carbon.The five-coordinated aluminum(Al^(Ⅴ))species are essential for achieving the atomic dispersion of Rh atoms,providing the unsaturated coordinative sites for metal.Compared to the benchmark Rh/γ-Al_(2)O_(3) and Rh/C nanocatalysts,the Rh@Al_(2)O_(3)@C SAC affords an excellent turnover frequency of 2317 molm-CNB·molRh^(–1)·h^(–1),the highest value to date in heterogeneous catalyst systems for the hydrogenation of m-CNB at 313 K and 20 bar H2,together with a sustained selectivity to m-CAN(~98%)during five consecutive runs.The superior catalytic performance of the Rh@Al_(2)O_(3)@C is attributed to a proper modulation of electronic structure of hydrogenation metal by forming SAC,together with an enhanced accessibility of acid function sites.
文摘Molecular catalysts for H2-evolution are of interest for their integration into light-harvesting complexes for photocatalytic water splitting.Here,we report the meso-tetra(4-carboxyphenyl)porphine[(TCPP)Pt^(Ⅱ)]complex as a molecular H2-evolving photocatalyst using chloranilic acid(CA)as a sacrificial electron donor,the choice of which is critical to the stability of the photocatalyst.When triethanolamine was used,[(TCPP)Pt^(Ⅱ)]decomposed to form Pt nanoparticles.Density functional theory calculations together with evidence from electrochemical and spectroscopic analyses suggested that the catalysis was possibly initiated by a proton-coupled electron transfer(PCET)to form[(TCPP)Pt^(Ⅰ)]-N-H,followed by another electron injection and protonation to form a[(TCPP)Pt^(Ⅱ)-hydride]-N-H intermediate that can release H2.As the whole catalytic cycle involves the injection of multiple electrons,a light-harvesting network should be helpful by providing multiple photo-induced electrons.Thus,we integrated this molecular catalyst into a light-harvesting metal-organic framework to boost its activity by~830 times.This work presents a mechanistic study of the photocatalytic H2 evolution and energy transfer and highlights the importance of a light-harvesting network for multiple electron injections.
基金the Foundation of Henan Province Key Technology R and D Program(Grant No.0423033700).
文摘The present paper addresses the subject of truss damage identification using measured frequency response functions (FRF). Damage identification matrix is formed using measured FRFs obtained from truss dynamic test. Then using principal component analysis (PCA),the variable space dimensions of damage identification matrix can be reduced,and original data characters of FRFs can be analyzed and extracted from lower dimension variable space. Thus truss damages can be identified using the multivariate control chart of first several order principal components which contain almost all of original data information. Without the need for modal parameters,the method avoids the errors of modal fitting. In order to validate the reliability of the method,a whole size truss was tested with six types of damage case concerning single or two element damages. The experimental result shows that the proposed method is straightforward and reliable for truss damage identification. Especially,the method has good applicability for the truss under noisy environment and non-linear cases.
基金Supported by Research Grant for Health Science and Technology of Pudong Health Bureau of Shanghai,No.PKJ2009-Y16
文摘AIM:To identify differentially expressed genes in quiescent and activated hepatic stellate cells(HSCs)and explore their functions.METHODS:HSCs were isolated from the normal Sprague Dawley rats by in suit perfusion of collagenase and pronase and density Nycodenz gradient centrifugation.Total RNA and mRNA of quiescent HSCs,and cultureactivated HSCs were extracted,quantified and reversely transcripted into cDNA.The global gene expression profile was analyzed by microarray with Affymetrix rat genechip.Differentially expressed genes were annotated with Gene Ontology(GO)and analyzed with Kyoto encyclopedia of genes and genomes(KEGG)pathway using the Database for Annotation,Visualization and Integrated Discovery.Microarray data were validated by quantitative real-time polymerase chain reaction(qRTPCR).The function of Wnt5a on human HSCs line LX-2 was assessed with lentivirus-mediated Wnt5a RNAi.The expression of Wnt5a in fibrotic liver of a carbon tetrachloride(CCl4)-induced fibrosis rat model was also analyzed with Western blotting.RESULTS:Of the 28 700 genes represented on this chip,2566 genes displayed at least a 2-fold increase or decrease in expression at a P<0.01 level with a false discovery rate.Of these,1396 genes were upregulated,while 1170 genes were downregulated in culture-activated HSCs.These differentially expressed transcripts were grouped into 545 GO based on biological process GO terms.The most enriched GO terms included response to wounding,wound healing,regulation of cell growth,vasculature development and actin cytoskeleton organization.KEGG pathway analysis revealed that Wnt5a signaling pathway participated in the activation of HSCs.Wnt5a was significantly increased in cultureactivated HSCs as compared with quiescent HSCs.qRTPCR validated the microarray data.Lentivirus-mediated suppression of Wnt5a expression in activated LX-2 resulted in significantly impaired proliferation,downregulated expressions of typeⅠcollagen and transforming growth factor-β1.Wnt5a was upregulated in the fibrotic liver of a CCl4-induced fibrosis rat model.CONCLUSION:Wnt5a is involved in the activation of HSCs,and it may serve as a novel therapeutic target in the treatment of liver fibrosis.
文摘Developing highly active and durable electrocatalysts for the oxygen reduction reaction (ORR) is crucial to large-scale commercialization of fuel cells and metal-air batteries. Here we report a facile approach for the synthesis of nitrogen and oxygen dual-doped meso-porous layer-structured carbon electrocatalyst embedded with graphitic carbon coated cobalt nanoparticles by direct pyrolysis of a layer-structured metal-organic framework. The elec- trocatalyst prepared at 800℃ exhibits comparable ORR performance to Pt/C catalysts but possesses superior stability to Pt/C catalysts. This synthetic approach provides new prospects in developing sustainable carbon-based electrocatalysts for electrochemical energy conversion devices.
基金supported by Energy Resource Technology Development Project [The Development and commercialization of Inorganic Polymer Ceramic Panel] of Korea Energy Management Corporationsupported by NCRC(National Core Research Center) Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology
文摘Inorganic polymers are a novel class of materials formed by the polymerization of silicon, aluminium and oxygen species to form an amorphous three-dimensional framework structure. The basis of this process is the alkaline solutions to induce a certain amount of Si and AI atoms to dissolve from a feedstock such as aluminosilicate. A study of 27A1 MAS-NMR was carried out in an attempt to understand the reaction mechanism of the inorganic polymerization at ambient temperature. Scanning electron microscopy (SEM) and X-ray diflYactometry (XRD) were also employed to establish the composition and microstructure of the inorganic polymerization. Specimens were prepared with different A1/Si mole ratios from the starting materials. The higher the AI content, the more sufficient the AI atoms that can combine with SiO4, and the longer the reaction time, the more the bonded Si--O--A1--O polymer structure, and then the higher the A1 content, the fewer the octahedral A1 with a uniform Si--O--A1--O structure in four directions, because four AI atoms are combined with SiO4, resulting in a uniform Si--O--AI--O structure in four directions. The results show that they have an amorphous microstructure.
文摘Objective To investigate the effect of Furongtongmai capsule on the in-stent restenosis (ISR) of superficial femoral artery after interventional operation in lower extremity Arteriosclerosis Occlusion (ASO). Methods: A total of 110 inpatients with ASO who performed Superficial femoral artery stent implantation were randomly divided into observation group and control group, with 55 cases in each group.Both groups received Aspirin 100 mg/d and Clopidogrel 75 mg/d. The observation group was given Furongtongmai capsule on the basis of routine treatment. After continuous treatment for 6 months, the clinical efficacy, Ankle Brachial Index (ABI), high-sensitivity C-reactive protein (Hs-CPR) and ISR were compared between the two groups. Results: At 6 months after operation, the plasma levels of Hs-CRP in the two groups were significantly lower than those in the control group (P 〈 0.05). The ABI of treatment group was significantly higher than the control group (P 〈 0.05). There was a statistically significant difference in ISR incidence between the treatment group and the control group 6 months after surgery (9.09% vs 27.78%, P 〈 0.05). Conclusion: Furongtongmai Capsule can inhibit Hs-CRP in patients with ASO after femoral artery intervention, improve the ankle brachial index and reduce the incidence of ISR.
基金supported by the National Natural Science Foundation of China (20902101 & 21172246)National Basic Research Program of China (973 Program) (2010CB833206)
文摘In our synthetic studies toward huperzine A, a diastereoselective α'-alkylation of the α-amido-γ-methyl hexenone 4 was real- ized through a dianion intermediate which significantly enhanced the reactivity. Under the attempted Heck reaction conditions, an unexpected and unprecedented palladium-catalyzed intramolecular T-arylation of 3 was observed, which generated 18 with bicyclo[3.3, l]nonane framework in satisfactory yield.
基金supported by the National Natural Science Foundation of China(21136001,21173018)
文摘Metal-organic framework MIL-53(Al) was synthesized by a solvothermal method using aluminum nitrate as the aluminium source and 1,4-benzenedicarboxylic acid(H2BDC) as the organic ligand. The structure of samples was characterized by X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR). The catalytic activity and recyclability of MIL-53(Al) catalyst for the Friedel-Crafts acylation reaction of indole with benzoyl chloride were evaluated. The reaction conditions were optimized and a reaction mechanism was suggested. The results showed that the MIL-53(Al) catalyst exhibited good catalytic activity and recyclability for the Friedel-Crafts acylation reaction. When the molar ratio of indole and MIL-53(Al) catalyst was 1:0.06(n1:ncatalyst), the molar ratio of indole and benzoyl chloride was 1:3, and the solvent was dichloromethane, the conversion of indole could reach 97.1% and the selectivity of 3-acylindole could reach 81.1% at 25 °C after 8 h. The catalyst can be reused without significant degradation in catalytic activity. After the catalyst was reused five times, the conversion of indole was 87.6% and the selectivity of 3-acylindole was 79.5%.