Aqueous zinc ion batteries have high potential applicability for energy storage due to their reliable safety,environmental friendliness,and low cost.However,the freezing of aqueous electrolytes limits the normal opera...Aqueous zinc ion batteries have high potential applicability for energy storage due to their reliable safety,environmental friendliness,and low cost.However,the freezing of aqueous electrolytes limits the normal operation of batteries at low temperatures.Herein,a series of high-performance and low-cost chloride hydrogel electrolytes with high concentrations and low freezing points are developed.The electrochemical windows of the chloride hydrogel electrolytes are enlarged by>1 V under cryogenic conditions due to the obvious evolution of hydrogen bonds,which highly facilitates the operation of electrolytes at ultralow temperatures,as evidenced by the low-temperature Raman spectroscopy and linear scanning voltammetry.Based on the Hofmeister effect,the hydrogen-bond network of the cooperative chloride hydrogel electrolyte comprising 3 M ZnCl_(2)and 6 M LiCl can be strongly interrupted,thus exhibiting a sufficient ionic conductivity of 1.14 mS cm;and a low activation energy of 0.21 e V at-50℃.This superior electrolyte endows a polyaniline/Zn battery with a remarkable discharge specific capacity of 96.5 mAh g;at-50℃,while the capacity retention remains~100%after 2000 cycles.These results will broaden the basic understanding of chloride hydrogel electrolytes and provide new insights into the development of ultralow-temperature aqueous batteries.展开更多
The adsorption behaviors of 1-naphthol, 1-naphthylamine and l-naphthol/l-naphthylamine mixtures in water over two macroreticular adsorbents were investigated in single or binary batch systems at 293 K, 303 K and 313 K...The adsorption behaviors of 1-naphthol, 1-naphthylamine and l-naphthol/l-naphthylamine mixtures in water over two macroreticular adsorbents were investigated in single or binary batch systems at 293 K, 303 K and 313 K respectively. All the adsorption isotherms in the studied systems can be adequately fitted by Langmuir model. In the case of aminated macroreticular adsorbent NDA103, 1-naphthol is adsorbed to a larger extent than 1-naphthylamine; while, the opposite trend is found for nonpolar macroreticular adsorbent NDA100. It is noteworthy that at higher temperature(303 K and 313 K), the total uptake amounts of 1-naphthol and 1-naphthylamine in all binary-component systems are obvious larger than the pure uptake amounts in single-component systems, which is presumably due to the cooperative effect primarily arisen from the hydrogen-bonding interaction between the loaded 1-naphthol and 1-naphthylamine molecules. The simultaneous adsorption systems were confirmed to be helpful to the selective adsorption towards 1-naphthol according to the larger selective index.展开更多
Molecular dynamics method was employed to study the binding energies of the selected crystal planes of the 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane(HMX)/1,3-dimethyl-2-imidazolidinone(DMI) cocrystal in differ...Molecular dynamics method was employed to study the binding energies of the selected crystal planes of the 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane(HMX)/1,3-dimethyl-2-imidazolidinone(DMI) cocrystal in different molecular molar ratios. The mechanical properties were estimated in different molar ratios. Solvent effects were evaluated and the cooperativity effects were discussed in the HMX···HF···DMI ternary by using the M06-2x/6-311+G(2df,2p) and MP2(full)/6-311+G(2df,2p) methods. The results indicate that the substituted patterns(020) and(100) own the highest binding energies. The stabilities of cocrystals in the 1:1 and 2:1 ratios are the greatest, and thus the HMX/DMI cocrystals prefer cocrystallizing in the 1:1 and 2:1 molar ratios, which have good mechanical properties. The sensitivity change of cocrystal originates from not only the formation of intermolecular interaction but also the increment of bond dissociation energy of the N–NO2 bond. The cooperativity effect appears in the linear complex while the anti-cooperativity effect is found in the cyclic system. DMI binding to HMX is not energetically and structurally favored in the presence of HF. This is perhaps the reason that the solvent with large dielectric constant weakens the stability of the HMX/DMI cocrystals. Therefore, the solvents with low dielectric constants should be chosen in the preparation of HMX/DMI cocrystals.展开更多
The influences of various kinds of UV-absorbers, antioxidants and their mixtures on UV-aging resis- tance of transparent unsaturated polyester FRP are studied by artificial aocelerating aging test.The results show tha...The influences of various kinds of UV-absorbers, antioxidants and their mixtures on UV-aging resis- tance of transparent unsaturated polyester FRP are studied by artificial aocelerating aging test.The results show that the UV-aging resistance of com- bined stabilizers is better than single stabilizer. It is concluded that the cooperative effect of UV -absorbers is caused bg the increase of wave leng- th and intensity of the absorption light the coopora- tive effect of UV-absorbers and antioxidants is caused by Dreventing the photo-oxidantion.展开更多
The bare amorphous Al_(2)O_(3)-AlPO_(4)and Cs/Al_(2)O_(3)-AlPO_(4)catalysts were developed for the aldol condensation of methyl acetate with formaldehyde to methyl acrylate.The structure and property of catalyst were ...The bare amorphous Al_(2)O_(3)-AlPO_(4)and Cs/Al_(2)O_(3)-AlPO_(4)catalysts were developed for the aldol condensation of methyl acetate with formaldehyde to methyl acrylate.The structure and property of catalyst were characterized by XRD,XPS,BET,Pyridine-IR,FT-IR,^(27)Al-MASNMR,NH_(3)-/CO_(2)-TPD and SEM.The correlation between structural features and acid-base properties was established,and the loading effect of the cesium species was investigated.Due to cooperative catalytic effects between the penta-coordinated Al and Al_(2)O_(3),the weak-Ⅱacid and medium acid site densities and the product selectivity were improved.While the basic site densities of these catalysts were almost in proportion to the conversion of methyl acetate.The loaded Cs could form new basic sites and change the distribution of acid sites which further enhance the catalytic performance.As a result,the 10Cs/8AlP was proved to be an optimal catalyst with the yield and selectivity of 21.2%and 85%for methyl acrylate respectively.During the reaction,a deactivation behavior was observed on 10Cs/8AlP catalyst due to the carbon deposition,however,it could be regenerated by thermal treatment in the air atmosphere at 400℃.展开更多
Fluoroacetate dehalogenases(FAcD),a homodimeric enzyme,catalyzes the conversion of fluoroacetic acid to glycolic acid(GoA).It has been proved that the enzyme has a half-of-the-site reactivity.Namely,its catalytic(C)su...Fluoroacetate dehalogenases(FAcD),a homodimeric enzyme,catalyzes the conversion of fluoroacetic acid to glycolic acid(GoA).It has been proved that the enzyme has a half-of-the-site reactivity.Namely,its catalytic(C)subunit converts the first substrate to a covalent intermediate;then,the non-catalytic(NC)subunit binds a second substrate and promotes the conversion of the intermediate in the C subunit into the final product.After the release of the product,the C subunit becomes the NC subunit,and the previous NC subunit becomes the C subunit.To elucidate the detailed mechanism behind this cooperative catalysis,we have conducted microsecond-scale MD simulations along the reaction pathway.The simulations indicate that the substrate in the NC subunit induces W185 and Y141 adopting an open conformation in the C subunit.The opening of W185(C)facilitates the entry of catalytic water,enhancing the catalytic activity for product formation,while the opening of Y141(C)creates an unfavorable environment for product binding,promoting its release.An interaction network analysis reveals that the substrate in the NC subunit can induce conformational changes through a conserved water chain at the interface.展开更多
Limited by the shuttle effect, the application of lithium-sulfur batteries is not impressive. As an organ layered two-dimensional(2D) material, MXene has a great electrical conductivity and high specific surface area....Limited by the shuttle effect, the application of lithium-sulfur batteries is not impressive. As an organ layered two-dimensional(2D) material, MXene has a great electrical conductivity and high specific surface area. Meanwhile, the introduction of metal oxides can restrain the shuttle effect. Hence, this paper prepared CeO_(2)/MXene as a cathode material of Li-S batteries. Ce and Ti can chemically adsorb S, and the interlayer structure of MXene can limit S while the interlayer space can alleviate volume expansion.The discharge capacity at 0.5 C is as high as 1051.1 m Ah g^(-1), and 921.9 m Ah g^(-1) after 200 cycles. The average coulombic efficiency is 97.75%. The organized MXene with CeO_(2) like notes in accordions are new efficient materials for lithium-sulfur batteries.展开更多
The binary adsorption behavior of 1-naphthol/1-naphthylamine mixtures in water on nonpolar adsorbent Amberlite XAD4 was investigated at 293 K, 303 K and 313 K, respectively. The experimental uptakes of 1-naphthol and ...The binary adsorption behavior of 1-naphthol/1-naphthylamine mixtures in water on nonpolar adsorbent Amberlite XAD4 was investigated at 293 K, 303 K and 313 K, respectively. The experimental uptakes of 1-naphthol and 1-naphthylamine in all binary-component systems of different molar ratios were obviously higher than the corresponding uptakes predicted by the extended Langmuir model, assuming no interaction between the adsorbed molecules of the two components. This phenomenon was attributed to the cooperative adsorption effect arising from the hydrogen bonding interaction between 1-naphthol and 1-naphthylamine molecules. A modified extended Langmuir model was proposed to describe the binary adsorption behavior by means of introducing a fitting parameter related with the cooperative adsorption effect of the adsorbates.展开更多
In the present study, we have investigated the reducibility of CuO species on CuO-CeO2 catalysts and the influence of CuO species on the catalytic performance for CO preferential oxidation (CO PROX) in excess hydrog...In the present study, we have investigated the reducibility of CuO species on CuO-CeO2 catalysts and the influence of CuO species on the catalytic performance for CO preferential oxidation (CO PROX) in excess hydrogen. It is revealed that the smaller the difference of reduction temperature (denoted as ?T) for two adjacent CuO species is, the higher the catalytic activity of CuO-CeO2 for the PROX in excess hydrogen may be obtained. It means that if the reduction energy of Cu0-Cu2+ pairs matched better, the reduction-oxidation recycle of Cu0-Cu2+ pairs would go on more easily, then the transferring energy of Cu0-Cu2+ pairs would be lesser. Therefore, the CuO-CeO2 catalysts will be largely improved in their catalytic performance if the different CuO species on the catalysts have matched the reduction energy, which would allows them to cooperate effectively.展开更多
Thermodynamic data were determined for the reversible binding of O 2 to two compounds of dicobalt(II) di(meso tetra phenyl)porphyrin derivatives with different lengths of diamidoaliphatic bridge (abbreviated to Co ...Thermodynamic data were determined for the reversible binding of O 2 to two compounds of dicobalt(II) di(meso tetra phenyl)porphyrin derivatives with different lengths of diamidoaliphatic bridge (abbreviated to Co 2PP 8 and Co 2PP 4) in N,N dimethylformamide at room temperature. The partial pressure of dioxygen necessary for half oxygenation ( P 1/2 ) and Hill coefficient ( n ) at 298 K were determined as follows: P 1/2 =54.2 kPa, n =2.0 for Co 2PP 8 and P 1/2 =6.8 kPa, n =1.8 for Co 2PP 4,respectively. The rate equations of reversible oxygen binding by Co 2PP 8 were determined and the reaction path was proposed. The results of thermodynamic and kinetic studies indicate that there exists strong cooperative effect during oxygenation of the compounds. The ESR observation reveals that the dioxygen complexes formed in the solutions are of superoxo (Co O - 2) type.展开更多
The cooperative effect plays a significant role in understanding the intermolecular donor-acceptor interactions of hydrogen bonds(H-bonds, D-H···A). Here, using the coupled-cluster singles and doubles w...The cooperative effect plays a significant role in understanding the intermolecular donor-acceptor interactions of hydrogen bonds(H-bonds, D-H···A). Here, using the coupled-cluster singles and doubles with perturbative triple excitations(CCSD(T)) method of high-precision ab initio calculations, we show that the intermolecular H-bonded systems with different D and A atoms reproduce the structural changes predicted by the well-known cooperative effect upon intermolecular compression. That is, with decreasing intermolecular distance, the D-H bond length first increases and then decreases, while the H···A distance decreases. On the contrary, when D and A are the same, as the intermolecular distance decreases, the D-H bond length decreases without increasing. This obvious difference means that the cooperative effect may not be generally characterized by intermolecular compression. Interestingly, further analyses of many intermolecular systems confirm that this failure has boundaries, i.e., cooperative systems at their respective equilibrium positions have a smaller core-valence bifurcation(CVB) index(<0.022) and stronger binding energies(>0.25 eV), showing a clear linear inverse relationship related to H-bond strength. These findings provide an important reference for the comprehensive understanding of H-bonds and its calculation methods.展开更多
Natural molecular chaperones utilize spatially ordered multiple molecular forces to effectively regulate protein folding.However,synthesis of such molecules is a big challenge.The concept of“aggregate science”provid...Natural molecular chaperones utilize spatially ordered multiple molecular forces to effectively regulate protein folding.However,synthesis of such molecules is a big challenge.The concept of“aggregate science”provides insights to construct chemical entities(aggregates)beyond molecular levels to mimic both the structure and function of natural chaperone.Inspired by this concept,herein we fabricate a novel multi-interaction(i.e.,electrostatic and hydrophobic interaction)cooperative nanochaperone(multi-co-nChap)to regulating protein folding.This multi-co-nChap is fabricated by rationally introducing electrostatic interactions to the surface(corona)and confined hydrophobic microdomains(shell)of traditional single-hydrophobic interaction nanochaperone.We demonstrate that the corona electrostatic attraction facilitates the diffusion of clients into the hydrophobic microdomains,while the shell electrostatic interaction balances the capture and release of clients.By finely synergizing corona electrostatic attraction with shell electrostatic repulsion and hydrophobic interaction,the optimized multi-co-nChap effectively facilitated de novo folding of nascent polypeptides.Moreover,the synergy between corona electrostatic attraction,shell electrostatic attraction and shell hydrophobic interaction significantly enhanced the capability of multi-co-nChap to protect native proteins from denaturation at harsh temperatures.This work provides important insights for understanding and design of nanochaperone,which is a kind of ordered aggregate with chaperone-like activity that beyond the level of single molecule.展开更多
Nowadays,thermal condition and solute field are considered as the potential dominant factors controlling competitive grain growth during directional solidification process.However,the controlling modes and critical co...Nowadays,thermal condition and solute field are considered as the potential dominant factors controlling competitive grain growth during directional solidification process.However,the controlling modes and critical conditions of competitive grain growth have been drastically debated over the past two decades.In this work,thermal condition and solute field are combined to study the competitive grain growth in the converging case by experimental observation and numerical simulation of bicrystal samples.We find the competitive grain growth is controlled by the cooperative effect of thermal condition and solute field,and the controlling modes are related to the bicrystal misorientation between favorably and unfavorably oriented grains.When the unfavorably oriented grain is low misoriented,unfavorably oriented grain dominates grain selection,and the competitive grain growth performs as solute field domination.However,with the increase of unfavorably oriented grain’s misorientation,the grain selection converts into favorably oriented grain domination,and the competitive grain growth changes to thermal condition domination.To explain these abnormal transformation phenomena,we propose a misorientation dependent thermal condition-solute field cooperative domination model and identify the critical conditions by a critical misorientation(θ_(cm)).According to dynamic equation of dendrite growth,we calculate the critical misorientationθ;to prove this model.The theoretical calculation results agree well with the experimental results.展开更多
The effects of Zr doping on the existence of Cu and the catalytic performance of Ce_(0.7−x)Zr_(x)Cu_(0.3)O_(2)for CO oxidation were investigated.The characterization results showed that all samples have a cubic struct...The effects of Zr doping on the existence of Cu and the catalytic performance of Ce_(0.7−x)Zr_(x)Cu_(0.3)O_(2)for CO oxidation were investigated.The characterization results showed that all samples have a cubic structure,and a small amount of Zr doping facilitates Cu^(2+) ions entering the CeO2 lattice,but excessive Zr doping leads to the formation of surface CuO crystals again.Thus,the number of oxygen vacancies caused by the Cu^(2+) entering the lattice(e.g.,Cu^(2+)-□-Ce^(4+);□:oxygen vacancy),and the amount of reducible copper species caused by CuO crystals,varies with the Zr doping.Catalytic CO oxidation tests indicated that the oxygen vacancy and the reducible copper species were the adsorption and activation sites of O_(2)and CO,respectively,and the cooperative effects between them accounted for the high CO oxidation activity.Thus,the samples x=0.1 and 0.3,which possessed the most oxygen vacancy or reducible copper species,showed the best activity for CO oxidation,with full CO conversion obtained at 110℃.The catalyst is also stable and has good resistance to water during the reaction.展开更多
In this paper,DFT method was used to study the relative stability of hydrogen bonding networks of numerous 512,51262 and 435663 water cluster isomers.Herein we introduced an optimized six-digit definition to character...In this paper,DFT method was used to study the relative stability of hydrogen bonding networks of numerous 512,51262 and 435663 water cluster isomers.Herein we introduced an optimized six-digit definition to characterize diverse sub-grouped hydrogen bonds to consider the cooperative effect of the nearest and nextnearest neighbor water molecules.There are totally 74 kinds of sub-grouped hydrogen bonds in cage hydrate clusters,and these energies can be obtained by iterative calculations.This improvement effectively explains some regularity contained in hydrogen bonding cooperative effect.In general,donor or acceptor fragment sharing identical value of three independent digits usually performs poor cooperative effect,indicating that the existence of those same-digital-array fragments is the necessary condition to judge poor cooperative effect.Vice versa,the existence of different-digital-array is also the necessary condition to judge strong cooperative effect.展开更多
The catalytic hydrogenation of carboxylic acid to alcohols is one of the important strategies for the conversion of biomass.Herein,a series of Ni-doped PtSn catalysts were prepared,characterized and studied in the hyd...The catalytic hydrogenation of carboxylic acid to alcohols is one of the important strategies for the conversion of biomass.Herein,a series of Ni-doped PtSn catalysts were prepared,characterized and studied in the hydrogenation of acetic acid.The Ni dopant has a strong interaction with Pt,which promotes the hydrogen adsorption,providing an activated hydrogen-rich environment for the hydrogenation.Meanwhile,the presence of Ni also improves the Pt dispersion,giving more accessible active sites for hydrogen activation.The cooperation of Pt and Ni significantly promotes the catalytic activity of the hydrogenation of acetic acid to ethanol.As a result,the catalyst with 0.1%Ni exhibits the best reaction activity,and its space time yield is twice as that of the PtSn/SiO2 catalyst.It provides a meaningful instruction on the catalyst design for the carboxylic acid hydrogenation.展开更多
Controlling the chemistry at the interface of nanocrystalline solids has been a challenge and an important goal to realize desired properties. Integrating two different types of materials has the potential to yield ne...Controlling the chemistry at the interface of nanocrystalline solids has been a challenge and an important goal to realize desired properties. Integrating two different types of materials has the potential to yield new functions resulting from cooperative effects between the two constituents. Metal-organic frameworks (MOFs) are unique in that they are constructed by linking inorganic units with organic linkers where the building units can be varied nearly at will. This flexibility has made MOFs ideal materials for the design of functional entities at interfaces and hence allowing control of properties. This review highlights the strategies employed to access synergistic functionality at the interface of nanocrystalline MOFs (nMOFs) and inorganic nanocrystals (NCs).展开更多
Oxygen reduction reaction(ORR)is the pivotal portion in many electrochemical energy conversion and storage technologies.However,the complex mechanisms and sluggish kinetics of ORR have also become one of the key issue...Oxygen reduction reaction(ORR)is the pivotal portion in many electrochemical energy conversion and storage technologies.However,the complex mechanisms and sluggish kinetics of ORR have also become one of the key issues hindering the development and application of these technologies.展开更多
In the lead halide perovskite solar cells(PSCs),the redox reaction of I-and Pb^(2+) ions in perovskite materials under the fabrication and operation processes causes the formation of defects to destroy the cell effici...In the lead halide perovskite solar cells(PSCs),the redox reaction of I-and Pb^(2+) ions in perovskite materials under the fabrication and operation processes causes the formation of defects to destroy the cell efficiency and long-term stability.Herein,we have employed a Co(Ⅱ)sulfophenyl porphyrin(CoTPPS)to modify the perovskite film.The sulfonic group could coordinate with Pb2+to efficiently passivate the uncoordinated Pb^(2+).Additionally,Co^(2+) ions in CoTPPS could react with I^(2) generated under the thermal and light stress to yield the Co^(3+) and I^(-),thus achieving the regeneration of I^(-) in perovskite film.Therefore,the CoTPPS could realize the targeted management of the imperfections in perovskite film.As a result,the modified PSCs reveal the remarkably enhanced cell perfor-mance.More importantly,the CoTPPS modified device retains 75%of its initial efficiency value storing at 85℃for 2000 h and about 70%of its efficiency when being continuously illuminated at a simulated sunlight for 1200 h.This strategy tackles the chemical reaction and inhibits the defect generation,thus improving the operational stability and efficiency of PSCs.展开更多
基金We acknowledge the financial support from the National Natural Science Foundation of China(NSFC)(21875055 and 21674031)the Natural Science Foundation of Guangdong Province of China(2019A1515110447)+3 种基金the Guangdong Basic and Applied Basic Research Foundation(2019B1515120008)the Key-Area Research and Development Program of Guangdong Province(2021B0101260001)and the Characteristic Innovation Research Project of College Teachers of Foshan(2019XCC03)Open access funding provided by Shanghai Jiao Tong University
文摘Aqueous zinc ion batteries have high potential applicability for energy storage due to their reliable safety,environmental friendliness,and low cost.However,the freezing of aqueous electrolytes limits the normal operation of batteries at low temperatures.Herein,a series of high-performance and low-cost chloride hydrogel electrolytes with high concentrations and low freezing points are developed.The electrochemical windows of the chloride hydrogel electrolytes are enlarged by>1 V under cryogenic conditions due to the obvious evolution of hydrogen bonds,which highly facilitates the operation of electrolytes at ultralow temperatures,as evidenced by the low-temperature Raman spectroscopy and linear scanning voltammetry.Based on the Hofmeister effect,the hydrogen-bond network of the cooperative chloride hydrogel electrolyte comprising 3 M ZnCl_(2)and 6 M LiCl can be strongly interrupted,thus exhibiting a sufficient ionic conductivity of 1.14 mS cm;and a low activation energy of 0.21 e V at-50℃.This superior electrolyte endows a polyaniline/Zn battery with a remarkable discharge specific capacity of 96.5 mAh g;at-50℃,while the capacity retention remains~100%after 2000 cycles.These results will broaden the basic understanding of chloride hydrogel electrolytes and provide new insights into the development of ultralow-temperature aqueous batteries.
基金The National Natural Science Foundation of China( No. 20274017) and the Nature Science Foundation of Jiangsu Province( No. BK2004415)
文摘The adsorption behaviors of 1-naphthol, 1-naphthylamine and l-naphthol/l-naphthylamine mixtures in water over two macroreticular adsorbents were investigated in single or binary batch systems at 293 K, 303 K and 313 K respectively. All the adsorption isotherms in the studied systems can be adequately fitted by Langmuir model. In the case of aminated macroreticular adsorbent NDA103, 1-naphthol is adsorbed to a larger extent than 1-naphthylamine; while, the opposite trend is found for nonpolar macroreticular adsorbent NDA100. It is noteworthy that at higher temperature(303 K and 313 K), the total uptake amounts of 1-naphthol and 1-naphthylamine in all binary-component systems are obvious larger than the pure uptake amounts in single-component systems, which is presumably due to the cooperative effect primarily arisen from the hydrogen-bonding interaction between the loaded 1-naphthol and 1-naphthylamine molecules. The simultaneous adsorption systems were confirmed to be helpful to the selective adsorption towards 1-naphthol according to the larger selective index.
文摘Molecular dynamics method was employed to study the binding energies of the selected crystal planes of the 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane(HMX)/1,3-dimethyl-2-imidazolidinone(DMI) cocrystal in different molecular molar ratios. The mechanical properties were estimated in different molar ratios. Solvent effects were evaluated and the cooperativity effects were discussed in the HMX···HF···DMI ternary by using the M06-2x/6-311+G(2df,2p) and MP2(full)/6-311+G(2df,2p) methods. The results indicate that the substituted patterns(020) and(100) own the highest binding energies. The stabilities of cocrystals in the 1:1 and 2:1 ratios are the greatest, and thus the HMX/DMI cocrystals prefer cocrystallizing in the 1:1 and 2:1 molar ratios, which have good mechanical properties. The sensitivity change of cocrystal originates from not only the formation of intermolecular interaction but also the increment of bond dissociation energy of the N–NO2 bond. The cooperativity effect appears in the linear complex while the anti-cooperativity effect is found in the cyclic system. DMI binding to HMX is not energetically and structurally favored in the presence of HF. This is perhaps the reason that the solvent with large dielectric constant weakens the stability of the HMX/DMI cocrystals. Therefore, the solvents with low dielectric constants should be chosen in the preparation of HMX/DMI cocrystals.
文摘The influences of various kinds of UV-absorbers, antioxidants and their mixtures on UV-aging resis- tance of transparent unsaturated polyester FRP are studied by artificial aocelerating aging test.The results show that the UV-aging resistance of com- bined stabilizers is better than single stabilizer. It is concluded that the cooperative effect of UV -absorbers is caused bg the increase of wave leng- th and intensity of the absorption light the coopora- tive effect of UV-absorbers and antioxidants is caused by Dreventing the photo-oxidantion.
基金supported by Key Research Program of Frontier Sciences(No.QYZDB-SSW-SLH022)National Natural Science Foundation of China(No.21676270,No.21878293,No.22178338)+1 种基金the Joint Fund of the Yulin University and the Dalian National-Laboratory for Clean Energy(Grant YLU-DNL Fund2021018)Foundation of State Key Laboratory of Highefficiency Utilization of Coal and Green Chemical Engineering(Grant No.2017-K08)。
文摘The bare amorphous Al_(2)O_(3)-AlPO_(4)and Cs/Al_(2)O_(3)-AlPO_(4)catalysts were developed for the aldol condensation of methyl acetate with formaldehyde to methyl acrylate.The structure and property of catalyst were characterized by XRD,XPS,BET,Pyridine-IR,FT-IR,^(27)Al-MASNMR,NH_(3)-/CO_(2)-TPD and SEM.The correlation between structural features and acid-base properties was established,and the loading effect of the cesium species was investigated.Due to cooperative catalytic effects between the penta-coordinated Al and Al_(2)O_(3),the weak-Ⅱacid and medium acid site densities and the product selectivity were improved.While the basic site densities of these catalysts were almost in proportion to the conversion of methyl acetate.The loaded Cs could form new basic sites and change the distribution of acid sites which further enhance the catalytic performance.As a result,the 10Cs/8AlP was proved to be an optimal catalyst with the yield and selectivity of 21.2%and 85%for methyl acrylate respectively.During the reaction,a deactivation behavior was observed on 10Cs/8AlP catalyst due to the carbon deposition,however,it could be regenerated by thermal treatment in the air atmosphere at 400℃.
基金supported by the Key-Area Research and Development Program of Guangdong Province(2020B0101350001)the Shenzhen Fundamental Research Program(GXWD2020123116580700720200812124825001)+1 种基金the Shenzhen Science and Technology Program(RCBS20210706092258097)supported by the Shenzhen Bay Laboratory Supercomputing Center。
文摘Fluoroacetate dehalogenases(FAcD),a homodimeric enzyme,catalyzes the conversion of fluoroacetic acid to glycolic acid(GoA).It has been proved that the enzyme has a half-of-the-site reactivity.Namely,its catalytic(C)subunit converts the first substrate to a covalent intermediate;then,the non-catalytic(NC)subunit binds a second substrate and promotes the conversion of the intermediate in the C subunit into the final product.After the release of the product,the C subunit becomes the NC subunit,and the previous NC subunit becomes the C subunit.To elucidate the detailed mechanism behind this cooperative catalysis,we have conducted microsecond-scale MD simulations along the reaction pathway.The simulations indicate that the substrate in the NC subunit induces W185 and Y141 adopting an open conformation in the C subunit.The opening of W185(C)facilitates the entry of catalytic water,enhancing the catalytic activity for product formation,while the opening of Y141(C)creates an unfavorable environment for product binding,promoting its release.An interaction network analysis reveals that the substrate in the NC subunit can induce conformational changes through a conserved water chain at the interface.
基金supported financially by the National Natural Science Foundation of China(21706043)。
文摘Limited by the shuttle effect, the application of lithium-sulfur batteries is not impressive. As an organ layered two-dimensional(2D) material, MXene has a great electrical conductivity and high specific surface area. Meanwhile, the introduction of metal oxides can restrain the shuttle effect. Hence, this paper prepared CeO_(2)/MXene as a cathode material of Li-S batteries. Ce and Ti can chemically adsorb S, and the interlayer structure of MXene can limit S while the interlayer space can alleviate volume expansion.The discharge capacity at 0.5 C is as high as 1051.1 m Ah g^(-1), and 921.9 m Ah g^(-1) after 200 cycles. The average coulombic efficiency is 97.75%. The organized MXene with CeO_(2) like notes in accordions are new efficient materials for lithium-sulfur batteries.
基金This study was funded by the National Natural Science Foundation of China(No.20274017)the Natural Science Foundation of Jiangsu Province(No.BK2004415).
文摘The binary adsorption behavior of 1-naphthol/1-naphthylamine mixtures in water on nonpolar adsorbent Amberlite XAD4 was investigated at 293 K, 303 K and 313 K, respectively. The experimental uptakes of 1-naphthol and 1-naphthylamine in all binary-component systems of different molar ratios were obviously higher than the corresponding uptakes predicted by the extended Langmuir model, assuming no interaction between the adsorbed molecules of the two components. This phenomenon was attributed to the cooperative adsorption effect arising from the hydrogen bonding interaction between 1-naphthol and 1-naphthylamine molecules. A modified extended Langmuir model was proposed to describe the binary adsorption behavior by means of introducing a fitting parameter related with the cooperative adsorption effect of the adsorbates.
基金supported by the State Key Laboratory of Heavy Oil Processing (No. 200803)the Ministry of Science and Technology of China (No.2005CB221406)
文摘In the present study, we have investigated the reducibility of CuO species on CuO-CeO2 catalysts and the influence of CuO species on the catalytic performance for CO preferential oxidation (CO PROX) in excess hydrogen. It is revealed that the smaller the difference of reduction temperature (denoted as ?T) for two adjacent CuO species is, the higher the catalytic activity of CuO-CeO2 for the PROX in excess hydrogen may be obtained. It means that if the reduction energy of Cu0-Cu2+ pairs matched better, the reduction-oxidation recycle of Cu0-Cu2+ pairs would go on more easily, then the transferring energy of Cu0-Cu2+ pairs would be lesser. Therefore, the CuO-CeO2 catalysts will be largely improved in their catalytic performance if the different CuO species on the catalysts have matched the reduction energy, which would allows them to cooperate effectively.
文摘Thermodynamic data were determined for the reversible binding of O 2 to two compounds of dicobalt(II) di(meso tetra phenyl)porphyrin derivatives with different lengths of diamidoaliphatic bridge (abbreviated to Co 2PP 8 and Co 2PP 4) in N,N dimethylformamide at room temperature. The partial pressure of dioxygen necessary for half oxygenation ( P 1/2 ) and Hill coefficient ( n ) at 298 K were determined as follows: P 1/2 =54.2 kPa, n =2.0 for Co 2PP 8 and P 1/2 =6.8 kPa, n =1.8 for Co 2PP 4,respectively. The rate equations of reversible oxygen binding by Co 2PP 8 were determined and the reaction path was proposed. The results of thermodynamic and kinetic studies indicate that there exists strong cooperative effect during oxygenation of the compounds. The ESR observation reveals that the dioxygen complexes formed in the solutions are of superoxo (Co O - 2) type.
基金supported by the 2020-JCJQ Project (No. GFJQ2126–007)National Natural Science Foundation of China (No. 11974136)。
文摘The cooperative effect plays a significant role in understanding the intermolecular donor-acceptor interactions of hydrogen bonds(H-bonds, D-H···A). Here, using the coupled-cluster singles and doubles with perturbative triple excitations(CCSD(T)) method of high-precision ab initio calculations, we show that the intermolecular H-bonded systems with different D and A atoms reproduce the structural changes predicted by the well-known cooperative effect upon intermolecular compression. That is, with decreasing intermolecular distance, the D-H bond length first increases and then decreases, while the H···A distance decreases. On the contrary, when D and A are the same, as the intermolecular distance decreases, the D-H bond length decreases without increasing. This obvious difference means that the cooperative effect may not be generally characterized by intermolecular compression. Interestingly, further analyses of many intermolecular systems confirm that this failure has boundaries, i.e., cooperative systems at their respective equilibrium positions have a smaller core-valence bifurcation(CVB) index(<0.022) and stronger binding energies(>0.25 eV), showing a clear linear inverse relationship related to H-bond strength. These findings provide an important reference for the comprehensive understanding of H-bonds and its calculation methods.
基金National Natural Science Foundation of China,Grant/Award Numbers:51933006,52373153,52293383National Key Research and Development Program of China,Grant/Award Number:2022YFA1205702Haihe Laboratory of Sustainable Chemical Transformations,Grant/Award Number:YYJC202102。
文摘Natural molecular chaperones utilize spatially ordered multiple molecular forces to effectively regulate protein folding.However,synthesis of such molecules is a big challenge.The concept of“aggregate science”provides insights to construct chemical entities(aggregates)beyond molecular levels to mimic both the structure and function of natural chaperone.Inspired by this concept,herein we fabricate a novel multi-interaction(i.e.,electrostatic and hydrophobic interaction)cooperative nanochaperone(multi-co-nChap)to regulating protein folding.This multi-co-nChap is fabricated by rationally introducing electrostatic interactions to the surface(corona)and confined hydrophobic microdomains(shell)of traditional single-hydrophobic interaction nanochaperone.We demonstrate that the corona electrostatic attraction facilitates the diffusion of clients into the hydrophobic microdomains,while the shell electrostatic interaction balances the capture and release of clients.By finely synergizing corona electrostatic attraction with shell electrostatic repulsion and hydrophobic interaction,the optimized multi-co-nChap effectively facilitated de novo folding of nascent polypeptides.Moreover,the synergy between corona electrostatic attraction,shell electrostatic attraction and shell hydrophobic interaction significantly enhanced the capability of multi-co-nChap to protect native proteins from denaturation at harsh temperatures.This work provides important insights for understanding and design of nanochaperone,which is a kind of ordered aggregate with chaperone-like activity that beyond the level of single molecule.
基金financially supported by the Shandong Provincial Natural Science Foundation(No.ZR2020ME110)the National Natural Science Foundation of China(Nos.51331005,U1508213,51771190 and 51601102)+2 种基金the Fund of the State Key Laboratory of Solidification Processing in NWPU(Nos.SKLSP201847 and SKLSP201834)the Young Doctors Cooperation Project in Qilu University of Technology(No.2018BSHZ003)the Key Research and Development Program of Ningxia(No.2019BDE03016)。
文摘Nowadays,thermal condition and solute field are considered as the potential dominant factors controlling competitive grain growth during directional solidification process.However,the controlling modes and critical conditions of competitive grain growth have been drastically debated over the past two decades.In this work,thermal condition and solute field are combined to study the competitive grain growth in the converging case by experimental observation and numerical simulation of bicrystal samples.We find the competitive grain growth is controlled by the cooperative effect of thermal condition and solute field,and the controlling modes are related to the bicrystal misorientation between favorably and unfavorably oriented grains.When the unfavorably oriented grain is low misoriented,unfavorably oriented grain dominates grain selection,and the competitive grain growth performs as solute field domination.However,with the increase of unfavorably oriented grain’s misorientation,the grain selection converts into favorably oriented grain domination,and the competitive grain growth changes to thermal condition domination.To explain these abnormal transformation phenomena,we propose a misorientation dependent thermal condition-solute field cooperative domination model and identify the critical conditions by a critical misorientation(θ_(cm)).According to dynamic equation of dendrite growth,we calculate the critical misorientationθ;to prove this model.The theoretical calculation results agree well with the experimental results.
基金support provided by the following organisations is gratefully acknowledged:the National Natural Science Foundation of China(Grant No.21976141)the Central Committee Guides Local Science and Technology Development Special Project of Hubei Province(Grant No.2019ZYYD073)+1 种基金the Outstanding Young and Middle-aged Scientific and Technological Innovation Team of the Education Department of Hubei Province(Grant No.T2020011)the Opening Project of Hubei Key Laboratory of Biomass Fibers and Eco-Dyeing&Finishing(Grant No.STRZ2020003).
文摘The effects of Zr doping on the existence of Cu and the catalytic performance of Ce_(0.7−x)Zr_(x)Cu_(0.3)O_(2)for CO oxidation were investigated.The characterization results showed that all samples have a cubic structure,and a small amount of Zr doping facilitates Cu^(2+) ions entering the CeO2 lattice,but excessive Zr doping leads to the formation of surface CuO crystals again.Thus,the number of oxygen vacancies caused by the Cu^(2+) entering the lattice(e.g.,Cu^(2+)-□-Ce^(4+);□:oxygen vacancy),and the amount of reducible copper species caused by CuO crystals,varies with the Zr doping.Catalytic CO oxidation tests indicated that the oxygen vacancy and the reducible copper species were the adsorption and activation sites of O_(2)and CO,respectively,and the cooperative effects between them accounted for the high CO oxidation activity.Thus,the samples x=0.1 and 0.3,which possessed the most oxygen vacancy or reducible copper species,showed the best activity for CO oxidation,with full CO conversion obtained at 110℃.The catalyst is also stable and has good resistance to water during the reaction.
基金supported by the National Natural Science Foundation of China(No.21672018)。
文摘In this paper,DFT method was used to study the relative stability of hydrogen bonding networks of numerous 512,51262 and 435663 water cluster isomers.Herein we introduced an optimized six-digit definition to characterize diverse sub-grouped hydrogen bonds to consider the cooperative effect of the nearest and nextnearest neighbor water molecules.There are totally 74 kinds of sub-grouped hydrogen bonds in cage hydrate clusters,and these energies can be obtained by iterative calculations.This improvement effectively explains some regularity contained in hydrogen bonding cooperative effect.In general,donor or acceptor fragment sharing identical value of three independent digits usually performs poor cooperative effect,indicating that the existence of those same-digital-array fragments is the necessary condition to judge poor cooperative effect.Vice versa,the existence of different-digital-array is also the necessary condition to judge strong cooperative effect.
基金The National Natural Science Foundation of China are acknowledged for the financial support on this work(Grant No.21878227).
文摘The catalytic hydrogenation of carboxylic acid to alcohols is one of the important strategies for the conversion of biomass.Herein,a series of Ni-doped PtSn catalysts were prepared,characterized and studied in the hydrogenation of acetic acid.The Ni dopant has a strong interaction with Pt,which promotes the hydrogen adsorption,providing an activated hydrogen-rich environment for the hydrogenation.Meanwhile,the presence of Ni also improves the Pt dispersion,giving more accessible active sites for hydrogen activation.The cooperation of Pt and Ni significantly promotes the catalytic activity of the hydrogenation of acetic acid to ethanol.As a result,the catalyst with 0.1%Ni exhibits the best reaction activity,and its space time yield is twice as that of the PtSn/SiO2 catalyst.It provides a meaningful instruction on the catalyst design for the carboxylic acid hydrogenation.
文摘Controlling the chemistry at the interface of nanocrystalline solids has been a challenge and an important goal to realize desired properties. Integrating two different types of materials has the potential to yield new functions resulting from cooperative effects between the two constituents. Metal-organic frameworks (MOFs) are unique in that they are constructed by linking inorganic units with organic linkers where the building units can be varied nearly at will. This flexibility has made MOFs ideal materials for the design of functional entities at interfaces and hence allowing control of properties. This review highlights the strategies employed to access synergistic functionality at the interface of nanocrystalline MOFs (nMOFs) and inorganic nanocrystals (NCs).
基金This work is supported by the Youth Innovation Promotion Association CAS(No.202055)the National Key R&D Program of China(2019YFA0709202,2020YFB2009004).
文摘Oxygen reduction reaction(ORR)is the pivotal portion in many electrochemical energy conversion and storage technologies.However,the complex mechanisms and sluggish kinetics of ORR have also become one of the key issues hindering the development and application of these technologies.
基金the Science and Technology Program of Gansu Province(20JR5RA305,21JR7RA147)the Fundamental Research Funds for,the Central Universities of China(Izujbky-2021-ey10)the Project of Young Teachers' Scientific Research Ability improvement Plan of Northwest Normal University(NWNU-LKQN2021-09).
文摘In the lead halide perovskite solar cells(PSCs),the redox reaction of I-and Pb^(2+) ions in perovskite materials under the fabrication and operation processes causes the formation of defects to destroy the cell efficiency and long-term stability.Herein,we have employed a Co(Ⅱ)sulfophenyl porphyrin(CoTPPS)to modify the perovskite film.The sulfonic group could coordinate with Pb2+to efficiently passivate the uncoordinated Pb^(2+).Additionally,Co^(2+) ions in CoTPPS could react with I^(2) generated under the thermal and light stress to yield the Co^(3+) and I^(-),thus achieving the regeneration of I^(-) in perovskite film.Therefore,the CoTPPS could realize the targeted management of the imperfections in perovskite film.As a result,the modified PSCs reveal the remarkably enhanced cell perfor-mance.More importantly,the CoTPPS modified device retains 75%of its initial efficiency value storing at 85℃for 2000 h and about 70%of its efficiency when being continuously illuminated at a simulated sunlight for 1200 h.This strategy tackles the chemical reaction and inhibits the defect generation,thus improving the operational stability and efficiency of PSCs.