An immature pinecone shaped hierarchically structured zirconia （ZrO2-ipch） and a cobblestone-like zirconia nanoparticulate （ZrO2-cs）, both with the monoclinic phase （m-phase）, were synthesized by the facile hydr...An immature pinecone shaped hierarchically structured zirconia （ZrO2-ipch） and a cobblestone-like zirconia nanoparticulate （ZrO2-cs）, both with the monoclinic phase （m-phase）, were synthesized by the facile hydrothermal method and used as the support for a Ni catalyst for the dry reforming of methane （DRM） with CO2. ZrO2-ipch is a much better support than ZrO2-cs and the traditional ZrO2 irregular particles made by a simple precipitation method （ZrO2-ip）. The supported Ni catalyst on ZrO2-ipch （Ni/ZrO2-ipch） exhibited outstanding catalytic activity and coke-resistant stability compared to the ones on ZrO2-cs （Ni/ZrO2-cs） and ZrO2-ip （Ni/ZrO2-ip）. Ni/ZrO2-ip exhibited the worst catalytic performance. The origin of the significantly enhanced catalytic performance was revealed by characterization including XRD, N2 adsorption measurement （BET）, TEM, H2-TPR, CO chemisorption, CO2-TPD, XPS and TGA. The superior catalytic activity of Ni/ZrO2-ipch to Ni/ZrO2-cs or Ni/ZrO2-ip was ascribed to a higher Ni dispersion, increased reducibility, enhanced oxygen mo- bility, and more basic sites with a higher strength, which were due to the unique hierarchically structural morphology of the ZrO2-ipch support. Ni/ZrO2-ipch exhibited better stability for the DRM reaction than Ni/ZrO2-ip, which was ascribed to its higher resistance to Ni sintering due to a strengthened metal-support interaction and the confinement effect of the mesopores and coke deposition resistance. The higher coking resistance of Ni/ZrO2-ipch for the DRM reaction in comparison with Ni/ZrOz-ip orignated from the coke-removalabitity of the higher amount of lattice oxygen and more basic sites, confirmed by XPS and CO2-TPD analysis, and the stabilized Ni on the Ni/ZrO2-ipch catalyst by the confinement effect of the mesopores of the hierarchical ZrO2-ipch sup- port. The superior catalytic performance and coking resistance of the Ni/ZrO2-ipch catalyst makes it a promising candidate for synthesis gas production from the DRM reaction.展开更多
Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic r...Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic reduction can reduce carbon dioxide into a series of alcohols and acidic organic molecules,which can effectively realize the utilization and transformation of carbon dioxide.This review focuses on the tuning strategies and structure effects of catalysts for the electrocatalytic CO_(2) reduction reaction(CO_(2)RR).The tuning strategies for the active sites of catalysts have been reviewed from intrinsic and external perspectives.The structure effects for the CO_(2)RR catalysts have also been discussed,such as tandem catalysis,synergistic effects and confinement catalysis.We expect that this review about tuning strategies and structure effects can provide guidance for designing highly efficient CO_(2)RR electrocatalysts.展开更多
Due to the randomness of earthquake wave magnitude and direction, and the uncertain direction of strong axis and weak axis in the construction of engineering structures, the effect of the direction of ground motion on...Due to the randomness of earthquake wave magnitude and direction, and the uncertain direction of strong axis and weak axis in the construction of engineering structures, the effect of the direction of ground motion on a structure are studied herein. Ground motion records usually contain three vertical ground motion data, which are obtained by sensors arranged in accordance with the EW （East -West） direction, NS （South- North） direction and perpendicular to the surface （z） direction, referring to the construction standard of seismic stations. The seismic records in the EW and NS directions are converted to Cartesian coordinates in accordance with the rotation of θ = 0°-180°, and consequently, a countless group of new ground motion time histories are obtained. Then, the characteristics of the ground motion time history and response spectrum of each group were studied, resulting in the following observations： （1） the peak and phase of ground motion are changed with the rotation of direction θ, so that the direction θ of the maximum peak ground motion can be determined; （2） response spectrum values of each group of ground motions change along with the direction θ, and their peak, predominant period and declining curve are also different as the changes occur; then, the angle θ in the direction of the maximum peak value or the widest predominant period can be determined; and （3） the seismic response of structures with different directions of ground motion inputs has been analyzed under the same earthquake record, and the results show the difference. For some ground motion records, such as the Taft seismic wave, these differences are significant. Next, the Lushan middle school gymnasium structure was analyzed and the calculation was checked using the proposed method, where the internal force of the upper space truss varied from 25% to 28%. The research results presented herein can be used for reference in choosing the ground motion when checking the actual damage to structures following earthquakes and explaining the seismic damage. Meanwhile, it also provides a reference value for research into the most severe ground motion.展开更多
Fischer-Tropsch synthesis （FTS） is an increasingly important approach for producing liquid fuels and chemicals via syngas-that is, synthesis gas, a mixture of carbon monoxide and hydrogen-generated from coal, natura...Fischer-Tropsch synthesis （FTS） is an increasingly important approach for producing liquid fuels and chemicals via syngas-that is, synthesis gas, a mixture of carbon monoxide and hydrogen-generated from coal, natural gas, or biomass. In FTS, dispersed transition metal nanoparticles are used to catalyze the reactions underlying the formation of carbon-carbon bonds. Catalytic activity and selectivity are strongly correlated with the electronic and geometric structure of the nanoparticles, which depend on the particle size, morphology, and crystallographic phase of the nanoparticles. In this article, we review recent works dealing with the aspects of bulk and surface sensitivity of the FTS reaction. Understanding the different catalytic behavior in more detail as a function of these parameters may guide the design of more active, selective, and stable FTS catalysts.展开更多
Cross-region innovation is widely recognized as an important source of the long-term regional innovation capacity.In the recent past,a growing number of studies has investigated the network structure and mechanisms of...Cross-region innovation is widely recognized as an important source of the long-term regional innovation capacity.In the recent past,a growing number of studies has investigated the network structure and mechanisms of cross-region innovation collaboration in various contexts.However,existing research mainly focuses on physical effects,such as geographical distance and high-speed railway connections.These studies ignore the intangible drivers in a changing environment,the more digitalized economy and the increasingly solidified innovation network structure.Thus,the focus of this study is on estimating determinants of innovation networks,especially on intangible drivers,which have been largely neglected so far.Using city-level data of Chinese patents(excluding Hong Kong,Macao,and Taiwan Province of China),we trace innovation networks across Chinese cities over a long period of time.By integrating a measure on Information and Communications Technology(ICT)development gap and network structural effects into the general proximity framework,this paper explores the changing mechanisms of Chinese innovation networks from a new perspective.The results show that the structure of cross-region innovation networks has changed in China.As mechanisms behind this development,the results confirm the increasingly important role of intangible drivers in Chinese inter-city innovation collaboration when controlling for effects of physical proximity,such as geographical distance.Since digitalization and coordinated development are the mainstream trends in China and other developing countries,these countries'inter-city innovation collaboration patterns will witness dramatic changes under the influence of intangible drivers.展开更多
Human capital is an important aspect of energy consumption,exerting crucial effects on economic growth,technological progress,and economic restructuring.This paper presents an in-depth investigation of the effect of h...Human capital is an important aspect of energy consumption,exerting crucial effects on economic growth,technological progress,and economic restructuring.This paper presents an in-depth investigation of the effect of human capital on energy consumption using an extended version of the Stochastic Impacts by Regression on Population,Affluence,and Technology framework.The estimated results using a panel dataset covering China’s 30 provincial regions during the period 1997-2018 and applying fixed effects with instrumental variables and the generalized method of moments indicated that an increase in human capital significantly drove energy consumption.A 1%increase in human capital increased energy consumption by approximately 0.3%.A two-step channel analysis to test scale,technical,and structural effects revealed that the positive effect of human capital on energy consumption is based primarily on the scale effect.However,highly educated human capital alleviates the energy pressure of this effect.In contrast to the scale effect,both the technical and structural effects of human capital reduced energy consumption,and this reduction is primarily correlated with enterprises’utility-oriented technological progress.Finally,we present strategic energy control policy implications related to human capital.展开更多
In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3O...In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3OH conversion and H_(2)yield,the reaction perfo rmance of the catalysts ranks as Cu/Sm_(2)O_(3)-M>Cu/Sm_(2)O_(3)-C>Cu/Gd_(2)O_(3)-M>Cu/Gd_(2)O_(3)-C>Cu/Eu_(2)O_(3)-M>Cu/Eu_(2)O_(3)-C.For the same kind of REO,Cu supported on the monoclinic support shows better performance than on the cubic one.Despite the phase structure difference,Sm_(2)O_(3) is the best support among all the three kinds of REOs.Compared with Cu/REO catalysts prepared with cubic supports,the corresponding catalysts prepared with monoclinic supports generally possess mo re surface oxygen vacancies,which can generate mo re surface active oxygen(O_(2)^(-)) and moderate basic sites.Moreover,the contents of Cu^(+) on the catalysts follow the same sequence.The reaction performance is positively related to the amount of these three types of surface sites.But metallic Cuo species is necessary to maintain the Cu^(+)■Cu^(0) redox cycle.Furthe rmore,on a catalyst with good perfo rmance,those vital surface reaction intermediates can be stabilized during the reaction.Cu/Sm_(2)O_(3)-M possesses the largest quantities of these surface sites,and has the appropriate amount of Cu^(+) and Cu^(0) after reduction,thereby displaying the optimal performance in all the catalysts.In conclusion,evident support crystal structure effect is observed for Cu/REO catalysts,and a monoclinic phase REO is a better support than the respective cubic phase one.展开更多
Based on the survey data of typical villages in Shaanxi Province,China,the effect of social capital on the income gap of farmers' households was analyzed using the Shapley value of the total amount of social capit...Based on the survey data of typical villages in Shaanxi Province,China,the effect of social capital on the income gap of farmers' households was analyzed using the Shapley value of the total amount of social capital and the social capital structure.The results show the following:first,social capital can expand the household income gap,and the effect of this index on the household income gap is 7.54%.Second,the indexes of the social capital dimension can expand the household income gap,and the structural effects of the household income gap on social networks,social trust,and social participation are 3.17%,3.64%,and 0.65%,respectively.Third,no dimension of the path is the same as the effect on the household income gap.展开更多
Calcium modified lead titanate nanocrystal material Pb0.85Ca0.15TiO3 was synthesized by means of a solgel method.The changes of crystal structure and grainsize of the samples were investigated under different conditio...Calcium modified lead titanate nanocrystal material Pb0.85Ca0.15TiO3 was synthesized by means of a solgel method.The changes of crystal structure and grainsize of the samples were investigated under different conditions of heat treatment.the results show that the tetragonal symmetry is reduced and the ferroelectricparaelectric phase transformation temperature is decreased with the reduce of the grainsize of the sample.the critical grainsize for the ferroelectricparaelectric phase transformation at room temperature was calculated.The change regularities of the lattice constant and tetragonality with the grainsize are discussed.展开更多
Barium titanate[BaTiO_(3)(BT)]-based ceramics are typical ferroelectric materials.Here,the discontinuous grain growth(DGG)and relevant grain size effect are deeply studied.An obvious DGG phenomenon is observed in a pa...Barium titanate[BaTiO_(3)(BT)]-based ceramics are typical ferroelectric materials.Here,the discontinuous grain growth(DGG)and relevant grain size effect are deeply studied.An obvious DGG phenomenon is observed in a paradigmatic Zr^(4+)-doped BT-based ceramic,with grains growing from∼2.2–6.6 to∼121.8–198.4μm discontinuously near 1320℃.It is found that fine grains can get together and grow into large ones with liquid phase surrounding them above eutectic temperature.Then the grain boundary density(D g)is quantitatively studied and shows a first-order reciprocal relationship with grain size,and the grain size effect is dependent on D g.Fine grains lead to high D g,and then cause fine domains and pseudocubic-like phase structure because of the interrupted long-range ferroelectric orders by grain boundary.High D g also causes the diffusion phase transition and low Curie dielectric peak due to the distribution of phase transition temperature induced by internal stress.Local domain switching experiments reveal that the polarization orientation is more difficult near the grain boundary,implying that the grain boundary inhibition dominates the process of polarization orientation in fine-grain ceramics,which leads to low polarization but a high coercive field.However,large-grain ceramics exhibit easy domain switching and high&similar ferroelectricity.This work reveals that the grain boundary effect dominates the grain size effect in fine-grain ceramics,and expands current knowledge on DGG and grain size effect in polycrystalline materials.展开更多
Rare-earth Sm^(3+)-doped Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.25PbTiO_(3)(PMN-0.25PT)ferroelectric ceramics with doping amounts between 0%-3%were developed via a conventional solid-state method.The doping effect of Sm^(3+)ions...Rare-earth Sm^(3+)-doped Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.25PbTiO_(3)(PMN-0.25PT)ferroelectric ceramics with doping amounts between 0%-3%were developed via a conventional solid-state method.The doping effect of Sm^(3+)ions on the PMN-0.25PT matrix was systematically investigated on the basis of the phase structure,temperature-dependent dielectric,ferroelectric,and electrotechnical properties.Due to the disruption of long-range ferroelectric order,the addition of Sm^(3+)ions effectively lowers the Tm(temperature corresponding to maximum permittivity)of the samples,leading to enhanced relaxor ferroelectric(RFE)characteristic and superior electric field-induced strain(electrostrain)properties at room temperature.Intriguingly,a considerable large-signal equivalent piezoelectric coefficient d∗_(33)of 2376 pm/V and a very small hysteresis were attained in the PMN-0.25PT component doped with 2.5 mol.%Sm^(3+).The findings of piezoelectric force microscopy indicate that the addition of Sm^(3+)increases the local structural heterogeneity of the PMN-0.25PT matrix and that the enhanced electromechanical performance is due to the dynamic behavior of polar nanoregions.Importantly,strong temperature-dependent electrostrain and electrostrictive coefficient Q33 are observed in the critical region around Tm in all Sm^(3+)-modified PMN-0.25PT ceramic samples studied.This work elucidates the phase transition behavior of Sm^(3+)-doped PMN-0.25PT and reveals a critical region where electrostrictive properties can be greatly improved due to a strong temperature-dependent characteristic.展开更多
The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the...The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall.展开更多
Large-scale gas accumulation areas in large oil-gas basins in central and Western China have multiple special accumulation mechanisms and different accumulation effects.Based on the geological theory and method of nat...Large-scale gas accumulation areas in large oil-gas basins in central and Western China have multiple special accumulation mechanisms and different accumulation effects.Based on the geological theory and method of natural gas reservoir formation,this study examined the regional geological and structural background,formation burial evolution,basic characteristics of gas reservoirs,and fluid geology and geochemistry of typical petroliferous basins.The results show that the geological processes such as structural pumping,mudstone water absorption,water-soluble gas degasification and fluid sequestration caused by uplift and denudation since Himalayan stage all can form large-scale gas accumulation and different geological effects of gas accumulation.For example,the large-scale structural pumping effect and fluid sequestration effect are conducive to the occurrence of regional ultra-high pressure fluid and the formation of large-scale ultra-high pressure gas field;mudstone water absorption effect in the formation with low thickness ratio of sandstone to formation is conducive to the development of regional low-pressure and water free gas reservoir;the water-soluble gas degasification effect in large-scale thick sandstone can not only form large-scale natural gas accumulation;moreover,the degasification of water-soluble gas produced by the lateral migration of formation water will produce regional and regular isotopic fractionation effect of natural gas,that is,the farther the migration distance of water-soluble gas is,the heavier the carbon isotopic composition of methane formed by the accumulation.展开更多
Cu-Ce-O catalysts, prepared by the amorphous citrate precursor (ACP) method, wereinvestigated by ICP, XRD and ndcro-reactor techniques. At low copper content of Cu-Ce-Ocatalysts, fluorite structures formed at low calc...Cu-Ce-O catalysts, prepared by the amorphous citrate precursor (ACP) method, wereinvestigated by ICP, XRD and ndcro-reactor techniques. At low copper content of Cu-Ce-Ocatalysts, fluorite structures formed at low calcining temperatures, and Cuo doped into the CeO2matrix; at high copper content, in addition to the fluorite structure, crystalline monoclinic phaseCuO formed as well at high calcining temperatures. There was no other phase formed even calcinedat 1000℃. The results show that only a little CuO dopes into the CeO2 matrix to form complexoxide, which promotes the catalytic activity of CO oxidation greatly. The optimum Cu-Ce-Ocatalyst is composed of 15% copper by Cu/(Ce+Cu) atomic ratio, and calcined at 700℃ for 4h. Thephase compositions include the crystalline CuO and the active complex oxide with fluoritestructure. The formulation of the active complex oxide is Cu0.06Ce0. 94O1.94.展开更多
In this paper, we review the magnetic properties and magnetocaloric effects（MCE） of binary R–T（R = Pr, Gd, Tb,Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series, R_（12...In this paper, we review the magnetic properties and magnetocaloric effects（MCE） of binary R–T（R = Pr, Gd, Tb,Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series, R_（12）Co_7 series, R_3 Co series and RCu_2series）, which have been investigated in detail in the past several years. The R–T compounds are studied by means of magnetic measurements, heat capacity measurements, magnetoresistance measurements and neutron powder diffraction measurements. The R–T compounds show complex magnetic transitions and interesting magnetic properties.The types of magnetic transitions are investigated and confirmed in detail by multiple approaches. Especially, most of the R–T compounds undergo more than one magnetic transition, which has significant impact on the magnetocaloric effect of R–T compounds. The MCE of R–T compounds are calculated by different ways and the special shapes of MCE peaks for different compounds are investigated and discussed in detail. To improve the MCE performance of R–T compounds,atoms with large spin（S） and atoms with large total angular momentum（J） are introduced to substitute the related rare earth atoms. With the atom substitution, the maximum of magnetic entropy change（？SM）, refrigerant temperature width（Twidth）or refrigerant capacity（RC） is enlarged for some R–T compounds. In the low temperature range, binary R–T（R = Pr, Gd,Tb, Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series,R_（12）Co_7 series, R_3 Co series and RCu_2series） show excellent performance of MCE, indicating the potential application for gas liquefaction in the future.展开更多
Diffusion has been systematically described as the main mechanism of chloride transport in reinforced concrete（RC） structure, especially when the concrete is in a saturated state. However, the single mechanism of di...Diffusion has been systematically described as the main mechanism of chloride transport in reinforced concrete（RC） structure, especially when the concrete is in a saturated state. However, the single mechanism of diffusion is not able to describe the actual chloride ingress in the nonsaturated concrete. Instead, it is dominated by the interaction of diffusion and convection. With the synergetic effects of various factors taken into account, this study aimed to modify and develop an analytical convection- diffusion coupling model for chloride transport in nonsaturated concrete. The model was verified by simulation of laboratory tests and field measurement. The results of comparison study demonstrate that the analytical model developed in this study is efficient and accurate in predicting the chloride profiles in the nonsaturated concrete.展开更多
Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring c...Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF （95 ）/VF （5）, VDF （52）/TrFE （48） and VDF（47. 5）/TrFE（47. 5）/HeFP （5） over a range of-120-140℃, 10-2-10;Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chainof PVDF led to disappearing of α-relaxation and increase in T;（3℃） of VDF （95）/VF （5）.Because of the spatial impediment of 5mol% HeFP in copolymer chain, the Curie point of VDF（52）/TrFE（48） decreased by 30℃ and T;by 3℃. The behavior of dielectric relaxation indicatedthat 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline regionreduced, the activation energy of local relaxation increased and the relaxation time prolonged respectively.展开更多
By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L...By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.展开更多
The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,...The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,but there are three π-π* bands each nt which displays chacactecistics of its own independently.These indicate that the two bridges-carbonyl-and-imino-can block the tlanSmlSSion of the conjngative polarization of the whole system,so as to form three segments,this is verified by means of chemical synthesis and degradation.展开更多
[Zn(POM)_2Br_2](POM is 3-Methyl-4-Nitropyridine-1-Oxide),C_(12)H_(12)Br_2N_4O_6Zn, Mr=533.44,triclinic,P1,a=11.450(3),b=13.027(2),c=6.605(1),α=101.25(1),β=96.96(2), γ=108.06(2)°,V=901.2(4)~3,Z=2,D_c=1.97g·...[Zn(POM)_2Br_2](POM is 3-Methyl-4-Nitropyridine-1-Oxide),C_(12)H_(12)Br_2N_4O_6Zn, Mr=533.44,triclinic,P1,a=11.450(3),b=13.027(2),c=6.605(1),α=101.25(1),β=96.96(2), γ=108.06(2)°,V=901.2(4)~3,Z=2,D_c=1.97g·cm^(-3),(MoK_α)=0.71069,F(000)=520, μ=58.21cm^(-1),final R=0.040 for 2192 observed reflections,T=296K.The compound is a mononuclear complex,containing a tetrahedrally coordinated zinc atom.展开更多
基金financially supported by the Joint Fund of Coal, set up by National Natural Science Foundation of China and Shenhua Co., Ltd.(U1261104)the National Natural Science Foundation of China (21276041)+3 种基金the Program for New Century Excellent Talents in University (NCET-12-0079)the Natural Science Foundation of Liaoning Province (2015020200)the Fundamental Research Funds for the Central Universities (DUT15LK41)the Science and Technology Development Program of Hangzhou (20130533B14)~~
文摘An immature pinecone shaped hierarchically structured zirconia （ZrO2-ipch） and a cobblestone-like zirconia nanoparticulate （ZrO2-cs）, both with the monoclinic phase （m-phase）, were synthesized by the facile hydrothermal method and used as the support for a Ni catalyst for the dry reforming of methane （DRM） with CO2. ZrO2-ipch is a much better support than ZrO2-cs and the traditional ZrO2 irregular particles made by a simple precipitation method （ZrO2-ip）. The supported Ni catalyst on ZrO2-ipch （Ni/ZrO2-ipch） exhibited outstanding catalytic activity and coke-resistant stability compared to the ones on ZrO2-cs （Ni/ZrO2-cs） and ZrO2-ip （Ni/ZrO2-ip）. Ni/ZrO2-ip exhibited the worst catalytic performance. The origin of the significantly enhanced catalytic performance was revealed by characterization including XRD, N2 adsorption measurement （BET）, TEM, H2-TPR, CO chemisorption, CO2-TPD, XPS and TGA. The superior catalytic activity of Ni/ZrO2-ipch to Ni/ZrO2-cs or Ni/ZrO2-ip was ascribed to a higher Ni dispersion, increased reducibility, enhanced oxygen mo- bility, and more basic sites with a higher strength, which were due to the unique hierarchically structural morphology of the ZrO2-ipch support. Ni/ZrO2-ipch exhibited better stability for the DRM reaction than Ni/ZrO2-ip, which was ascribed to its higher resistance to Ni sintering due to a strengthened metal-support interaction and the confinement effect of the mesopores and coke deposition resistance. The higher coking resistance of Ni/ZrO2-ipch for the DRM reaction in comparison with Ni/ZrOz-ip orignated from the coke-removalabitity of the higher amount of lattice oxygen and more basic sites, confirmed by XPS and CO2-TPD analysis, and the stabilized Ni on the Ni/ZrO2-ipch catalyst by the confinement effect of the mesopores of the hierarchical ZrO2-ipch sup- port. The superior catalytic performance and coking resistance of the Ni/ZrO2-ipch catalyst makes it a promising candidate for synthesis gas production from the DRM reaction.
文摘Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic reduction can reduce carbon dioxide into a series of alcohols and acidic organic molecules,which can effectively realize the utilization and transformation of carbon dioxide.This review focuses on the tuning strategies and structure effects of catalysts for the electrocatalytic CO_(2) reduction reaction(CO_(2)RR).The tuning strategies for the active sites of catalysts have been reviewed from intrinsic and external perspectives.The structure effects for the CO_(2)RR catalysts have also been discussed,such as tandem catalysis,synergistic effects and confinement catalysis.We expect that this review about tuning strategies and structure effects can provide guidance for designing highly efficient CO_(2)RR electrocatalysts.
基金National Technology Research and Development Program of the Ministry of Science and Technology of China under Grant No.2015BAK17B03National Natural Science Foundation of China(General Program)under Grant No.51278152+1 种基金National Science & Technology Pillar Program(2015BAK17B06)Program for Innovation Research Team in China Earthquake Administration
文摘Due to the randomness of earthquake wave magnitude and direction, and the uncertain direction of strong axis and weak axis in the construction of engineering structures, the effect of the direction of ground motion on a structure are studied herein. Ground motion records usually contain three vertical ground motion data, which are obtained by sensors arranged in accordance with the EW （East -West） direction, NS （South- North） direction and perpendicular to the surface （z） direction, referring to the construction standard of seismic stations. The seismic records in the EW and NS directions are converted to Cartesian coordinates in accordance with the rotation of θ = 0°-180°, and consequently, a countless group of new ground motion time histories are obtained. Then, the characteristics of the ground motion time history and response spectrum of each group were studied, resulting in the following observations： （1） the peak and phase of ground motion are changed with the rotation of direction θ, so that the direction θ of the maximum peak ground motion can be determined; （2） response spectrum values of each group of ground motions change along with the direction θ, and their peak, predominant period and declining curve are also different as the changes occur; then, the angle θ in the direction of the maximum peak value or the widest predominant period can be determined; and （3） the seismic response of structures with different directions of ground motion inputs has been analyzed under the same earthquake record, and the results show the difference. For some ground motion records, such as the Taft seismic wave, these differences are significant. Next, the Lushan middle school gymnasium structure was analyzed and the calculation was checked using the proposed method, where the internal force of the upper space truss varied from 25% to 28%. The research results presented herein can be used for reference in choosing the ground motion when checking the actual damage to structures following earthquakes and explaining the seismic damage. Meanwhile, it also provides a reference value for research into the most severe ground motion.
基金financial support by NWO-VICI and NWO-TOP grants awarded to Emiel J.M.Hensen
文摘Fischer-Tropsch synthesis （FTS） is an increasingly important approach for producing liquid fuels and chemicals via syngas-that is, synthesis gas, a mixture of carbon monoxide and hydrogen-generated from coal, natural gas, or biomass. In FTS, dispersed transition metal nanoparticles are used to catalyze the reactions underlying the formation of carbon-carbon bonds. Catalytic activity and selectivity are strongly correlated with the electronic and geometric structure of the nanoparticles, which depend on the particle size, morphology, and crystallographic phase of the nanoparticles. In this article, we review recent works dealing with the aspects of bulk and surface sensitivity of the FTS reaction. Understanding the different catalytic behavior in more detail as a function of these parameters may guide the design of more active, selective, and stable FTS catalysts.
基金Under the auspices of China Scholarship Council。
文摘Cross-region innovation is widely recognized as an important source of the long-term regional innovation capacity.In the recent past,a growing number of studies has investigated the network structure and mechanisms of cross-region innovation collaboration in various contexts.However,existing research mainly focuses on physical effects,such as geographical distance and high-speed railway connections.These studies ignore the intangible drivers in a changing environment,the more digitalized economy and the increasingly solidified innovation network structure.Thus,the focus of this study is on estimating determinants of innovation networks,especially on intangible drivers,which have been largely neglected so far.Using city-level data of Chinese patents(excluding Hong Kong,Macao,and Taiwan Province of China),we trace innovation networks across Chinese cities over a long period of time.By integrating a measure on Information and Communications Technology(ICT)development gap and network structural effects into the general proximity framework,this paper explores the changing mechanisms of Chinese innovation networks from a new perspective.The results show that the structure of cross-region innovation networks has changed in China.As mechanisms behind this development,the results confirm the increasingly important role of intangible drivers in Chinese inter-city innovation collaboration when controlling for effects of physical proximity,such as geographical distance.Since digitalization and coordinated development are the mainstream trends in China and other developing countries,these countries'inter-city innovation collaboration patterns will witness dramatic changes under the influence of intangible drivers.
文摘Human capital is an important aspect of energy consumption,exerting crucial effects on economic growth,technological progress,and economic restructuring.This paper presents an in-depth investigation of the effect of human capital on energy consumption using an extended version of the Stochastic Impacts by Regression on Population,Affluence,and Technology framework.The estimated results using a panel dataset covering China’s 30 provincial regions during the period 1997-2018 and applying fixed effects with instrumental variables and the generalized method of moments indicated that an increase in human capital significantly drove energy consumption.A 1%increase in human capital increased energy consumption by approximately 0.3%.A two-step channel analysis to test scale,technical,and structural effects revealed that the positive effect of human capital on energy consumption is based primarily on the scale effect.However,highly educated human capital alleviates the energy pressure of this effect.In contrast to the scale effect,both the technical and structural effects of human capital reduced energy consumption,and this reduction is primarily correlated with enterprises’utility-oriented technological progress.Finally,we present strategic energy control policy implications related to human capital.
基金Project supported by the National Natural Science Foundation of China(22172071,22102069,22062013,22262021,21962009)Natural Science Foundation of Jiangxi Province,China(20202BAB203006,20212BAB203030)Key Laboratory Foundation of Jiangxi Province for Environment and Energy Catalysis,China(20181BCD40004).
文摘In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3OH conversion and H_(2)yield,the reaction perfo rmance of the catalysts ranks as Cu/Sm_(2)O_(3)-M>Cu/Sm_(2)O_(3)-C>Cu/Gd_(2)O_(3)-M>Cu/Gd_(2)O_(3)-C>Cu/Eu_(2)O_(3)-M>Cu/Eu_(2)O_(3)-C.For the same kind of REO,Cu supported on the monoclinic support shows better performance than on the cubic one.Despite the phase structure difference,Sm_(2)O_(3) is the best support among all the three kinds of REOs.Compared with Cu/REO catalysts prepared with cubic supports,the corresponding catalysts prepared with monoclinic supports generally possess mo re surface oxygen vacancies,which can generate mo re surface active oxygen(O_(2)^(-)) and moderate basic sites.Moreover,the contents of Cu^(+) on the catalysts follow the same sequence.The reaction performance is positively related to the amount of these three types of surface sites.But metallic Cuo species is necessary to maintain the Cu^(+)■Cu^(0) redox cycle.Furthe rmore,on a catalyst with good perfo rmance,those vital surface reaction intermediates can be stabilized during the reaction.Cu/Sm_(2)O_(3)-M possesses the largest quantities of these surface sites,and has the appropriate amount of Cu^(+) and Cu^(0) after reduction,thereby displaying the optimal performance in all the catalysts.In conclusion,evident support crystal structure effect is observed for Cu/REO catalysts,and a monoclinic phase REO is a better support than the respective cubic phase one.
基金supported by the Natural Science Foundation of China(grant No.71173174)
文摘Based on the survey data of typical villages in Shaanxi Province,China,the effect of social capital on the income gap of farmers' households was analyzed using the Shapley value of the total amount of social capital and the social capital structure.The results show the following:first,social capital can expand the household income gap,and the effect of this index on the household income gap is 7.54%.Second,the indexes of the social capital dimension can expand the household income gap,and the structural effects of the household income gap on social networks,social trust,and social participation are 3.17%,3.64%,and 0.65%,respectively.Third,no dimension of the path is the same as the effect on the household income gap.
文摘Calcium modified lead titanate nanocrystal material Pb0.85Ca0.15TiO3 was synthesized by means of a solgel method.The changes of crystal structure and grainsize of the samples were investigated under different conditions of heat treatment.the results show that the tetragonal symmetry is reduced and the ferroelectricparaelectric phase transformation temperature is decreased with the reduce of the grainsize of the sample.the critical grainsize for the ferroelectricparaelectric phase transformation at room temperature was calculated.The change regularities of the lattice constant and tetragonality with the grainsize are discussed.
基金financially supported by the National Natu-ral Science Foundation of China(Nos.12104093,52072075,and 52102126)the Natural Science Foundation of Fujian Province(Nos.2021J05122,2021J05123,2022J01087,and 2022J01552)+2 种基金the Sichuan Province Science and Technology Support Program(No.2021YJ0560,22ZDYF3306,2022NSFSC1970,and 2022YFG0099)the Qishan Scholar Financial Support from Fuzhou University(No.GXRC-20099)the Fundamental Research Funds for the Central Universities,Southwest Minzu University(No.2020NTD03).
文摘Barium titanate[BaTiO_(3)(BT)]-based ceramics are typical ferroelectric materials.Here,the discontinuous grain growth(DGG)and relevant grain size effect are deeply studied.An obvious DGG phenomenon is observed in a paradigmatic Zr^(4+)-doped BT-based ceramic,with grains growing from∼2.2–6.6 to∼121.8–198.4μm discontinuously near 1320℃.It is found that fine grains can get together and grow into large ones with liquid phase surrounding them above eutectic temperature.Then the grain boundary density(D g)is quantitatively studied and shows a first-order reciprocal relationship with grain size,and the grain size effect is dependent on D g.Fine grains lead to high D g,and then cause fine domains and pseudocubic-like phase structure because of the interrupted long-range ferroelectric orders by grain boundary.High D g also causes the diffusion phase transition and low Curie dielectric peak due to the distribution of phase transition temperature induced by internal stress.Local domain switching experiments reveal that the polarization orientation is more difficult near the grain boundary,implying that the grain boundary inhibition dominates the process of polarization orientation in fine-grain ceramics,which leads to low polarization but a high coercive field.However,large-grain ceramics exhibit easy domain switching and high&similar ferroelectricity.This work reveals that the grain boundary effect dominates the grain size effect in fine-grain ceramics,and expands current knowledge on DGG and grain size effect in polycrystalline materials.
基金the National Natural Science Foundation of China(Grant No.52261135548)the Key Research and Development Program of Shaanxi(Program No.2022KWZ-22)+3 种基金the National Key Research and Development Program of China(Grant Nos.2021YFE0115000 and 2021YFB3800602)Russian Science Foundation(Project No.23-42-00116)the Ural Center for Shared Use“Modern nanotechnology”Ural Federal University(Reg.No.2968)which is supported by the Ministry of Science and Higher Education RF(Project No.075-15-2021-677)was used.The SEM work was done at International Center for Dielectric Research(ICDR),Xi’an Jiaotong University,Xi’an,China.
文摘Rare-earth Sm^(3+)-doped Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.25PbTiO_(3)(PMN-0.25PT)ferroelectric ceramics with doping amounts between 0%-3%were developed via a conventional solid-state method.The doping effect of Sm^(3+)ions on the PMN-0.25PT matrix was systematically investigated on the basis of the phase structure,temperature-dependent dielectric,ferroelectric,and electrotechnical properties.Due to the disruption of long-range ferroelectric order,the addition of Sm^(3+)ions effectively lowers the Tm(temperature corresponding to maximum permittivity)of the samples,leading to enhanced relaxor ferroelectric(RFE)characteristic and superior electric field-induced strain(electrostrain)properties at room temperature.Intriguingly,a considerable large-signal equivalent piezoelectric coefficient d∗_(33)of 2376 pm/V and a very small hysteresis were attained in the PMN-0.25PT component doped with 2.5 mol.%Sm^(3+).The findings of piezoelectric force microscopy indicate that the addition of Sm^(3+)increases the local structural heterogeneity of the PMN-0.25PT matrix and that the enhanced electromechanical performance is due to the dynamic behavior of polar nanoregions.Importantly,strong temperature-dependent electrostrain and electrostrictive coefficient Q33 are observed in the critical region around Tm in all Sm^(3+)-modified PMN-0.25PT ceramic samples studied.This work elucidates the phase transition behavior of Sm^(3+)-doped PMN-0.25PT and reveals a critical region where electrostrictive properties can be greatly improved due to a strong temperature-dependent characteristic.
基金Financial supports for this work, provided by the New Century Excellent Talents in University (No.NCET-05-0480)the Research Fund of the State Key Laboratory of Coal Resources and Mine Safety of CUMT (No.09KF06)the Scientific Research Fund of CUMT (No.OA090239)
文摘The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall.
基金Supported by the National Science and Technology Major Project(2016ZX05003-002)Scientific Research Project of Petro China Company Limited(2016E-0601)
文摘Large-scale gas accumulation areas in large oil-gas basins in central and Western China have multiple special accumulation mechanisms and different accumulation effects.Based on the geological theory and method of natural gas reservoir formation,this study examined the regional geological and structural background,formation burial evolution,basic characteristics of gas reservoirs,and fluid geology and geochemistry of typical petroliferous basins.The results show that the geological processes such as structural pumping,mudstone water absorption,water-soluble gas degasification and fluid sequestration caused by uplift and denudation since Himalayan stage all can form large-scale gas accumulation and different geological effects of gas accumulation.For example,the large-scale structural pumping effect and fluid sequestration effect are conducive to the occurrence of regional ultra-high pressure fluid and the formation of large-scale ultra-high pressure gas field;mudstone water absorption effect in the formation with low thickness ratio of sandstone to formation is conducive to the development of regional low-pressure and water free gas reservoir;the water-soluble gas degasification effect in large-scale thick sandstone can not only form large-scale natural gas accumulation;moreover,the degasification of water-soluble gas produced by the lateral migration of formation water will produce regional and regular isotopic fractionation effect of natural gas,that is,the farther the migration distance of water-soluble gas is,the heavier the carbon isotopic composition of methane formed by the accumulation.
文摘Cu-Ce-O catalysts, prepared by the amorphous citrate precursor (ACP) method, wereinvestigated by ICP, XRD and ndcro-reactor techniques. At low copper content of Cu-Ce-Ocatalysts, fluorite structures formed at low calcining temperatures, and Cuo doped into the CeO2matrix; at high copper content, in addition to the fluorite structure, crystalline monoclinic phaseCuO formed as well at high calcining temperatures. There was no other phase formed even calcinedat 1000℃. The results show that only a little CuO dopes into the CeO2 matrix to form complexoxide, which promotes the catalytic activity of CO oxidation greatly. The optimum Cu-Ce-Ocatalyst is composed of 15% copper by Cu/(Ce+Cu) atomic ratio, and calcined at 700℃ for 4h. Thephase compositions include the crystalline CuO and the active complex oxide with fluoritestructure. The formulation of the active complex oxide is Cu0.06Ce0. 94O1.94.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274357,51501005,51590880,and 11674008)the Fundamental Research Funds for the Central Universities,China(Grant No.FRF-TP-15-010A1)+1 种基金the China Postdoctoral Science Foundation(Grant No.2016M591071)the Key Research Program of the Chinese Academy of Sciences(Grant No.KJZD-EW-M05)
文摘In this paper, we review the magnetic properties and magnetocaloric effects（MCE） of binary R–T（R = Pr, Gd, Tb,Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series, R_（12）Co_7 series, R_3 Co series and RCu_2series）, which have been investigated in detail in the past several years. The R–T compounds are studied by means of magnetic measurements, heat capacity measurements, magnetoresistance measurements and neutron powder diffraction measurements. The R–T compounds show complex magnetic transitions and interesting magnetic properties.The types of magnetic transitions are investigated and confirmed in detail by multiple approaches. Especially, most of the R–T compounds undergo more than one magnetic transition, which has significant impact on the magnetocaloric effect of R–T compounds. The MCE of R–T compounds are calculated by different ways and the special shapes of MCE peaks for different compounds are investigated and discussed in detail. To improve the MCE performance of R–T compounds,atoms with large spin（S） and atoms with large total angular momentum（J） are introduced to substitute the related rare earth atoms. With the atom substitution, the maximum of magnetic entropy change（？SM）, refrigerant temperature width（Twidth）or refrigerant capacity（RC） is enlarged for some R–T compounds. In the low temperature range, binary R–T（R = Pr, Gd,Tb, Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu） intermetallic compounds（including RGa series, RNi series,R_（12）Co_7 series, R_3 Co series and RCu_2series） show excellent performance of MCE, indicating the potential application for gas liquefaction in the future.
基金Funded by the National Natural Science Foundation of China(Nos.51278304,U1134209,U1434204&51422814)the National Basic Research Program(973 Program)of China(No.011-CB013604)the Technology Research and Development Program(Basic Research Project)of Shenzhen(Nos.JCYJ20120613174456685&JCYJ20130329143859418)
文摘Diffusion has been systematically described as the main mechanism of chloride transport in reinforced concrete（RC） structure, especially when the concrete is in a saturated state. However, the single mechanism of diffusion is not able to describe the actual chloride ingress in the nonsaturated concrete. Instead, it is dominated by the interaction of diffusion and convection. With the synergetic effects of various factors taken into account, this study aimed to modify and develop an analytical convection- diffusion coupling model for chloride transport in nonsaturated concrete. The model was verified by simulation of laboratory tests and field measurement. The results of comparison study demonstrate that the analytical model developed in this study is efficient and accurate in predicting the chloride profiles in the nonsaturated concrete.
文摘Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF （95 ）/VF （5）, VDF （52）/TrFE （48） and VDF（47. 5）/TrFE（47. 5）/HeFP （5） over a range of-120-140℃, 10-2-10;Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chainof PVDF led to disappearing of α-relaxation and increase in T;（3℃） of VDF （95）/VF （5）.Because of the spatial impediment of 5mol% HeFP in copolymer chain, the Curie point of VDF（52）/TrFE（48） decreased by 30℃ and T;by 3℃. The behavior of dielectric relaxation indicatedthat 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline regionreduced, the activation energy of local relaxation increased and the relaxation time prolonged respectively.
文摘By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.
文摘The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,but there are three π-π* bands each nt which displays chacactecistics of its own independently.These indicate that the two bridges-carbonyl-and-imino-can block the tlanSmlSSion of the conjngative polarization of the whole system,so as to form three segments,this is verified by means of chemical synthesis and degradation.
文摘[Zn(POM)_2Br_2](POM is 3-Methyl-4-Nitropyridine-1-Oxide),C_(12)H_(12)Br_2N_4O_6Zn, Mr=533.44,triclinic,P1,a=11.450(3),b=13.027(2),c=6.605(1),α=101.25(1),β=96.96(2), γ=108.06(2)°,V=901.2(4)~3,Z=2,D_c=1.97g·cm^(-3),(MoK_α)=0.71069,F(000)=520, μ=58.21cm^(-1),final R=0.040 for 2192 observed reflections,T=296K.The compound is a mononuclear complex,containing a tetrahedrally coordinated zinc atom.
