期刊文献+
共找到37篇文章
< 1 2 >
每页显示 20 50 100
Co-doping of Iron and Cerium in Titanium Dioxide: Observation of a Cooperative Effect 被引量:11
1
作者 李晓俊 司德君 +2 位作者 方均 姜志全 黄伟新 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2006年第6期539-542,共4页
The co-doping of iron and cerium into TiO2 was studied by means of X-ray diffraction, Raman spectroscopy, UV Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, when separately doping via the so... The co-doping of iron and cerium into TiO2 was studied by means of X-ray diffraction, Raman spectroscopy, UV Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, when separately doping via the sol-gel method, iron was introduced in the fralnework of anatase TiO2 whereas cerium was not; interestingly, both iron and cerium were introduced in tile framework when co-doping by the sol-gel method. The co-doped TiO2 behaves much more intense surface hydroxyl concentration than the separately-doped and pure TiO2. This observation demonstrates for the first time a cooperative effect in the co-doping of transitional metals in the framework of TiO2. 展开更多
关键词 Titanium dioxide IRON CERIUM DOPING Cooperative effect
下载PDF
INTEGRATION OF HUMAN FACTORS ENGINEERING AND QUALITY MANAGEMENT 被引量:1
2
作者 卢岚 秦嵩 +1 位作者 陆全 Dessouky MohomedI 《Transactions of Tianjin University》 EI CAS 2001年第3期178-181,共4页
Human factors engineering and quality management are different research branches in the field of industrial engineering.A basis for interaction based on the concepts and techniques of human factors engineering and qua... Human factors engineering and quality management are different research branches in the field of industrial engineering.A basis for interaction based on the concepts and techniques of human factors engineering and quality management with some practical examples of cooperative effect is defined in this paper.The specific challenges about the quality management in manufacturing and service are presented to demonstrate that the human factors analysis of quality problems leads to new tends for integrated development. 展开更多
关键词 human factors engineering quality management integrated development cooperative effect
下载PDF
Cooperative Chloride Hydrogel Electrolytes Enabling Ultralow-Temperature Aqueous Zinc Ion Batteries by the Hofmeister Effect 被引量:6
3
作者 Changyuan Yan Yangyang Wang +1 位作者 Xianyu Deng Yonghang Xu 《Nano-Micro Letters》 SCIE EI CAS CSCD 2022年第6期219-233,共15页
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
关键词 Chloride hydrogel Electrochemical window Cooperative effect HYDROGEN-BOND Ultralow temperature Aqueous zinc ion battery
下载PDF
Transformation of carbon dioxide into valuable chemicals over bifunctional metallosalen catalysts bearing quaternary phosphonium salts 被引量:3
4
作者 Wuying Zhang Rongchang Luo +4 位作者 Qihang Xu Yaju Chen Xiaowei Lin Xiantai Zhou Hongbing Ji 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2017年第4期736-744,共9页
The chemical transformation of CO2under mild conditions remains a great challenge because of itsexceptional kinetic and thermodynamic stability.Two important reactions in the transformation ofCO2are the N‐formylation... The chemical transformation of CO2under mild conditions remains a great challenge because of itsexceptional kinetic and thermodynamic stability.Two important reactions in the transformation ofCO2are the N‐formylation reaction of amines using hydrosilanes and CO2,and the cycloaddition ofCO2to epoxides.Here,we report the high efficiency of bifunctional metallosalen complexes bearingquaternary phosphonium salts in catalyzing both of these reactions under solvent‐free,mild conditionswithout the need for co‐catalysts.The catalysts’bifunctionality is attributed to an intramolecularcooperative process between the metal center and the halogen anion.Depending on the reaction,this activates CO2by permitting either the synergistic activation of Si–H bond via metal–hydrogen coordinative bond(M–H)or the dual activation of epoxide via metal–oxygen coordinativebond(M–O).The one‐component catalysts are also shown to be easily recovered and reusedfive times without significant loss of activity or selectivity.The current results are combined withprevious work in the area to propose the relevant reaction mechanisms. 展开更多
关键词 Carbon dioxide Salen catalyst Quaternary phosphonium salt Cooperative effect Reaction mechanism
下载PDF
Binding Equilibrium Studies Between Co^(2+) and HSA or BSA 被引量:3
5
作者 BIAN He dong LIANG Hong +2 位作者 TU Chu qiao ZHANG Hong zhi SHEN Pan wen 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2000年第3期276-279,共4页
关键词 Co 2+ serum albumin Equilibrium dialysis Coordination analysis Positive cooperative effect
下载PDF
Effects of the surface chemistry of macroreticular adsorbents on the adsorption of 1-naphthol/1-naphthylamine mixtures from water 被引量:2
6
作者 ZHANG Wei-ming CHEN Jin-long +3 位作者 CHEN Qun HE Min-yang PAN Bing-cai ZHANG Quan-xing 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2005年第5期782-785,共4页
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
关键词 macroreticular adsorbent ADSORPTION 1-NAPHTHOL 1-NAPHTHYLAMINE cooperative effect
下载PDF
Zinc phthalocyanine as an efficient catalyst for halogen-free synthesis of formamides from amines via carbon dioxide hydrosilylation under mild conditions 被引量:3
7
作者 Rongchang Luo Xiaowei Lin +2 位作者 Jing Lu Xiantai Zhou Hongbing Ji 《Chinese Journal of Catalysis》 CSCD 北大核心 2017年第8期1382-1389,共8页
The combination of a zinc phthalocyanine(ZnPc)catalyst and a stoichiometric amount of dimethyl formamide(DMF)provided a simple route to formamide derivatives from amines,CO2,and hydrosilanes under mild conditions.We d... The combination of a zinc phthalocyanine(ZnPc)catalyst and a stoichiometric amount of dimethyl formamide(DMF)provided a simple route to formamide derivatives from amines,CO2,and hydrosilanes under mild conditions.We deduced that formation of an active zinc‐hydrogen(Zn‐H)species promoted hydride transfer from the hydrosilane to CO2.The cooperative activation of the Lewis acidic ZnPc by strongly polar DMF,led to formation of activated amines and hydrosilanes,which promoted the chemical reduction of CO2.Consequently,the binary ZnPc/DMF catalytic system showed excellent yields and superior chemoselectivity,representing a simple and sustainable pathway for the reductive transformation of CO2into valuable chemicals as an alternative to conventional halogen‐containing process. 展开更多
关键词 Carbon dioxide Zinc phthalocyanine Cooperative effect N‐formylation HYDROSILANES
下载PDF
Incorporation of flexible ionic polymers into a Lewis acid-functionalized mesoporous silica for cooperative conversion of CO2 to cyclic carbonates 被引量:2
8
作者 Ruqun Guan Xiaoming Zhang +2 位作者 Fangfang Chang Nan Xue Hengquan Yang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第12期1874-1883,共10页
A rational integration of multiple reactive centers into a combined unit to facilitate their cooperative effects is a smart approach for accelerating the catalytic activity.Here,to achieve this goal,linear imidazolium... A rational integration of multiple reactive centers into a combined unit to facilitate their cooperative effects is a smart approach for accelerating the catalytic activity.Here,to achieve this goal,linear imidazolium-based ionic polymers were confined into the nanopores of mesoporous silica nanospheres anchored with homogeneously distributed zinc salts.Owing to the flexible character and the reinforced cooperative effects of the ionic liquid(nucleophile)and zinc species(Lewis acid)in the confined mesoporous structure,the resultant composite exhibited dramatically improved catalytic performance in the cycloaddition of CO2 with epoxides to form cyclic carbonates.This was in contrast to that observed for the individual catalytic components.Moreover,such a solid catalyst could be easily recovered and reused four times without a significant loss of activity. 展开更多
关键词 Mesoporous silica Flexible ionic polymer Cooperative effects CO2 utilization Heterogeneous catalysis
下载PDF
ADSORPTION OF LATERALLY INTERACTING 1-NAPHTHOL/1-NAPHTHYL-AMINE MIXTURES ON NONPOLAR SURFACES FROM AQUEOUS SOLUTIONS 被引量:1
9
作者 Wei-ming Zhang Jin-long Chen +2 位作者 Qun Chen Ming-yang He Bing-cai Pan and Quan-xing Zhang a State Key Laboratory of Pollution Control and Resources Reuse,School of the Environment,Nanjing University,Nanjing 210093,China b Research Center for Engineering Technology of Organic Poison Control and Resources Reuse in Jiangsu Province,Nanjing 210038,China c Department of Chemical Engineering,Jiangsu Polytechnic,Changzhou 213016,China 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2006年第1期73-80,共8页
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
关键词 Modified model 1-NAPHTHOL 1-NAPHTHYLAMINE Adsorbate-adsorbate interaction Cooperative effect.
下载PDF
Notes in accordions-organized MXene equipped with CeO_(2) for synergistically adsorbing and catalyzing polysulfides for high-performance lithium-sulfur batteries 被引量:1
10
作者 Xiaochuan Chen Libo Li +3 位作者 Yuhang Shan Da Zhou Wenjun Cui Yangmingyue Zhao 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第7期502-510,I0013,共10页
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
关键词 Cooperative effects MXene CeO_(2) Kinetics Lithium-sulfur batteries
下载PDF
Influence of reduction energy match among CuO species in CuO-CeO_2 catalysts on the catalytic performance for CO preferential oxidation in excess hydrogen 被引量:1
11
作者 Zhigang Liu Yunlong Xie +2 位作者 Wensheng Li Renxian Zhou Xiaoming Zheng 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2011年第2期111-116,共6页
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
关键词 energy match cooperative effect CuO-CeO2 preferential oxidation CO
下载PDF
Cooperative structure-directing effect of choline cation and *BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolite 被引量:1
12
作者 Wenhua Fu Zhiqing Yuan +6 位作者 Shaoqing Jin Wei Liu Zhendong Wang Chuanming Wang Yangdong Wang Weimin Yang Ming-Yuan He 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第6期856-866,共11页
In this contribution,we report the cooperative structure-directing effect of choline hydroxide and aluminosilicate*BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolites for the first time.*BEA zeolites,a... In this contribution,we report the cooperative structure-directing effect of choline hydroxide and aluminosilicate*BEA zeolite in the synthesis of aluminogermanosilicate IWR zeolites for the first time.*BEA zeolites,at variance with any other aluminosilicate zeolites,can serve as heterogeneous seeds for the growth of IWR zeolites and play a cooperative structure-directing role.The crystallization process was investigated using multiple techniques to characterize a series of solid products obtained with various crystallization times.The experiments clearly showed the dissolution of the*BEA zeolite and of an intermediate CDO-type structure.A plausible mechanism for the novel cooperative synthesis has been proposed.The crystallization of the IWR zeolite involves several steps,among which the crucial one is believed to be the reassembly of the building units produced from the decomposition of*BEA zeolite seeds,induced by choline molecules.Having similar structure and common building units(four-,five-,and six-membered rings)with the IWR zeolite,the*BEA zeolite is capable of promoting the reassembly of the building units and can thus play a cooperative structure-directing role.By highlighting the cooperative structure-directing effect of organic molecules and heterogeneous seeds,this study opens up new perspectives for the synthesis of target zeolites that are difficult to prepare by traditional methods.This new synthetic route is also expected to shed light on the discovery of novel zeolites. 展开更多
关键词 IWR zeolite Cooperative structure-directing effect Organic structure-directing agent Choline cation Heterogeneous seeds *BEA zeolite
下载PDF
Theoretical Insight into the Influence of Molecular Ratio on the Stability, Mechanical Property, Solvent Effect and Cooperativity Effect of HMX/DMI Cocrystal Explosive 被引量:1
13
作者 李永祥 陈树森 +1 位作者 任福德 金韶华 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2017年第4期562-574,共13页
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
关键词 HMX/DMI cocrystal molecular dynamics molecular ratios sensitivity cooperativity effect
下载PDF
THE COOPERATIVE EFFECTS OF COMBINED STABILIZERS ON TRANSPARENT UNSATURATED POLYESTER FRP
14
作者 刘雄亚 熊传溪 连福茂 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 1989年第1期19-26,共8页
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
关键词 COMBINATION Stabilizerl Transparent unsaturated polyester Clear FRP Cooperative effect
下载PDF
Cooperative catalytic effects between the penta-coordinated Al and Al_(2)O_(3)in Al_(2)O_(3)-AlPO_(4)for aldol condensation of methyl acetate with formaldehyde to methyl acrylate
15
作者 Zhenyu Wu Zengxi Li Chunshan Li 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2022年第12期172-183,共12页
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
关键词 Methyl acrylate(MA) Aldol condensation Al_(2)O_(3)-AlPO_(4) Penta-coordinated aluminum Cooperative effects
下载PDF
The Strong Cooperativity of Dioxygen Binding by Dicobalt(II) Diporphyrin Compounds in Nonaqueous Solution at Room Temperature
16
作者 Zhou Xiaohai Deng Lizhi +4 位作者 Wu Xuye Zhang Shaohui Liu Shengquan Huang Suqiu Qu Songsheng 《Wuhan University Journal of Natural Sciences》 CAS 1997年第4期102-106,共5页
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
关键词 dicobalt(II) diporphyrin model compounds of hemoglobin cooperative effect reversible dioxygen binding THERMODYNAMICS kinetics
下载PDF
Identification of Connection Flexibility Effects Based on Load Testing of a Steel-Concrete Bridge
17
作者 Czeslaw Machelski Robert Toczkiewicz 《Journal of Civil Engineering and Architecture》 2012年第11期1504-1513,共10页
In the case of composite girders, an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs, used commonly in bridge structures, doe... In the case of composite girders, an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs, used commonly in bridge structures, does not provide full interaction of a steel beam and a concrete slab. This changes strain distribution in cross-sections of a composite girder and results in redistribution of internal forces in steel and concrete element. In the paper partial interaction index defined on the basis of a neutral axis position, which can be used for verification of steel-concrete interaction in real bridge structures rather than in specimens is proposed. The range of the index value changes, obtained during load testing of a typical steel-concrete composite beam bridge, is presented. The investigation was carried out on a motorway viaduct, consisting of two parallel structures. During the testing values of strains in girders under static and quasi-static loads were measured. The readings from the gauges were used to determine the index, characterizing composite action of the girders. Results of bridge testing under movable load, changing position along the bridge span is presented and obtained in-situ influence functions of strains and index values are commented in the paper. 展开更多
关键词 Abstract: In the case of composite girders an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs used commonly in bridge structures does not provide full interaction of a steel beam and a concrete slab. This changes strain distribution in cross-sections of a composite girder and results in redistribution of internal forces in steel and concrete element. In the paper partial interaction index defined on the basis of a neutral axis position which can be used for verification of steel-concrete interaction in real bridge structures rather Composite bridge partial interaction
下载PDF
Hydrogen Bonds in Perovskite for Efficient and Stable Photovoltaic
18
作者 Tian-yun Wang Yang-yang Hao +2 位作者 Ming-zhe Zhu Guo-rui Cao Zhong-min Zhou 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2024年第11期1284-1306,共23页
Owing to their distinctive optical and physical properties,organic-inorganic hybrid perovskite materials have gained significant attention in the field of electronic devices,especially solar cells.The achievement of h... Owing to their distinctive optical and physical properties,organic-inorganic hybrid perovskite materials have gained significant attention in the field of electronic devices,especially solar cells.The achievement of high-performance solar cells hinges upon the utilization of top-notch perovskite thin films.Nevertheless,the fabrication process involving solutions and the polycrystalline nature of perovskite result in the emergence of numerous defects within the perovskite films,consequently exerting a deleterious influence on the overall performance and stability of the devices.Improving the performance and stability of perovskite solar cells by additive engineering to suppress/passivate defects is a viable approach,which involves hydrogen bond interactions in these device engineering processes.This review explores the intrinsic hydrogen bonds in methylammonium and formamidium lead triiodide,while also considering cation rotations,phase transitions,and stability.Moreover,the review classifies additives into distinct categories,including organic small molecules,polymers,nanodots,classical salts,ionic liquids,and molten salts.The various forms and characterization techniques of hydrogen bonds are discussed,as well as their potential synergistic effects in conjunction with other chemical interactions.Furthermore,this review offers insights into the potential utilization of hydrogen bonds to further enhance the performance and stability of devices. 展开更多
关键词 Perovskite solar cells Hydrogen bond ADDITIVE Performance Stability Charge transfer INHIBITION Cooperative effects
原文传递
Heterometallic Mg-Ni-Mg Complex Promoted Hydrosilylation of Alkenes: Catalytic Performance and Intermediates Characterization
19
作者 Yanping Cai Shengjie Jiang Xin Xu 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2024年第18期2133-2139,共7页
Background and Originality Content The catalytic hydrosilylation of unsaturated hydrocarbons,facilitated by transition metal(TM),is widely recognized as a proficient technique for the synthesis of high-value organosil... Background and Originality Content The catalytic hydrosilylation of unsaturated hydrocarbons,facilitated by transition metal(TM),is widely recognized as a proficient technique for the synthesis of high-value organosilicon compounds'ti-4l over the past few decades,the most dominant cata.lysts in hydrosilylation processes have been constituted by pre-Ccious metar complexesroceinerecent vears omore sustainabile earth-abundant metal catalysts have received increased attentionj2-14l The classcal mechanism of transition metal-catalyzed hydrosilylation is generally accomplished through a series of fundamental processes(Scheme 1a),including(i)coordination and oxidative addition of Si-H bond to a low-valent metal center to form e.g.,o-complex or silyl metal hydride;(ii)insertion of.C-C multipe bonds intometal-hdridelsior metal-silicon bond;jiol and(ii)reductive elimination that forwards the hydrosilylated product with Markovnikov or anti-Markovnikov selectivity. 展开更多
关键词 Heterometallic complex Cooperative effect HYDROSILYLATION Magnesium Nickel hydride
原文传递
Understanding the cooperative effects in the catalysis of homodimeric fluoroacetate dehalogenase
20
作者 Ke-Wei Chen Jia-Nan Chen +3 位作者 Jun Zhang Chao Wang Tian-Yu Sun Yun-Dong Wu 《Science China Chemistry》 SCIE EI CAS CSCD 2024年第7期2382-2391,共10页
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
关键词 enzyme catalysis molecular dynamics cooperative effect pre-reaction state
原文传递
上一页 1 2 下一页 到第
使用帮助 返回顶部