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Underlying mechanism of the hydrothermal instability of Cu

Nadeen Al-Janabi,Abdullatif Alfutimie,Flor R. Siperstein,Xiaolei Fan

《化学科学与工程前沿（英文）》 2016年第10卷第1期页码 103-107 doi: 10.1007/s11705-015-1552-0

摘要： Water induced decomposition of Cu (BTC) (BTC= benzene-1,3,5-tricarboxylate) metal-organic framework (MOF) was studied using dynamic water vapour adsorption. Small-angle X-ray scattering, Fourier transform infrared spectroscopy and differential scanning calorimetry analyses revealed that the underlying mechanism of Cu (BTC) MOF decomposition under humid streams is the interpenetration of water molecules into Cu-BTC coordination to displace organic linkers (BTC) from Cu centres.

关键词： hydrothermal stability metal-organic framework (MOF) open metal sites (OMSs) dynamic water vapour adsorption

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Solid-state NMR for metal-containing zeolites: From active sites to reaction mechanism

Xingling Zhao, Jun Xu, Feng Deng

《化学科学与工程前沿（英文）》 2020年第14卷第2期页码 159-187 doi: 10.1007/s11705-019-1885-1

摘要： Metal-containing zeolite catalysts have found a wide range of applications in heterogeneous catalysis. To understand the nature of metal active sites and the reaction mechanism over such catalysts is of great importance for the establishment of structure-activity relationship. The advanced solid-state NMR (SSNMR) spectroscopy is robust in the study of zeolites and zeolite-catalyzed reactions. In this review, we summarize recent developments and applications of SSNMR for exploring the structure and property of active sites in metal-containing zeolites. Moreover, detailed information on host-guest interactions in the relevant zeolite catalysis obtained by SSNMR is also discussed. Finally, we highlight the mechanistic understanding of catalytic reactions on metal-containing zeolites based on the observation of key surface species and active intermediates.

关键词： metal-containing zeolites solid-state NMR active site host-guest interaction reaction mechanism

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An integrated optimization and simulation approach for air pollution control under uncertainty in open-pitmetal mine

Zunaira Asif, Zhi Chen

《环境科学与工程前沿（英文）》 2019年第13卷第5期 doi: 10.1007/s11783-019-1156-x

摘要： Air Pollution Control model is developed for open-pit metal mines. Model will aid decision makers to select a cost-effective solution. Open-pit metal mines contribute toward air pollution and without effective control techniques manifests the risk of violation of environmental guidelines. This paper establishes a stochastic approach to conceptualize the air pollution control model to attain a sustainable solution. The model is formulated for decision makers to select the least costly treatment method using linear programming with a defined objective function and multi-constraints. Furthermore, an integrated fuzzy based risk assessment approach is applied to examine uncertainties and evaluate an ambient air quality systematically. The applicability of the optimized model is explored through an open-pit metal mine case study, in North America. This method also incorporates the meteorological data as input to accommodate the local conditions. The uncertainties in the inputs, and predicted concentration are accomplished by probabilistic analysis using Monte Carlo simulation method. The output results are obtained to select the cost-effective pollution control technologies for PM2.5, PM10, NOx, SO2 and greenhouse gases. The risk level is divided into three types (loose, medium and strict) using a triangular fuzzy membership approach based on different environmental guidelines. Fuzzy logic is then used to identify environmental risk through stochastic simulated cumulative distribution functions of pollutant concentration. Thus, an integrated modeling approach can be used as a decision tool for decision makers to select the cost-effective technology to control air pollution.

关键词： Air pollution Decision analysis Linear programming Mining Optimization Fuzzy Monte Carlo

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Spin polarization strategy to deploy proton resource over atomic-level metal sites for highly selective

《化学科学与工程前沿（英文）》 2022年第16卷第12期页码 1772-1781 doi: 10.1007/s11705-022-2197-4

摘要： Unlocking of the extremely inert C=O bond during electrochemical CO₂ reduction demands subtle regulation on a key “resource”, protons, necessary for intermediate conversion but also readily trapped in water splitting, which is still challenging for developing efficient single-atom catalysts limited by their structural simplicity usually incompetent to handle this task. Incorporation of extra functional units should be viable. Herein, a proton deployment strategy is demonstrated via “atomic and nanostructured iron (A/N-Fe) pairs”, comprising atomically dispersed iron active centers spin-polarized by nanostructured iron carbide ferromagnets, to boost the critical protonation steps. The as-designed catalyst displays a broad window (300 mV) for CO selectivity > 90% (98% maximum), even outperforming numerous cutting-edge M–N–C systems. The well-placed control of proton dynamics by A/N-Fe can promote *COOH/*CO formation and simultaneously suppress H₂ evolution, benefiting from the magnetic-proximity-induced exchange splitting (spin polarization) that properly adjusts energy levels of the Fe sites’ d-shells, and further those of the adsorbed intermediates’ antibonding molecular orbitals.

关键词： CO₂ electrolysis single-atom catalysts spin polarization proton dynamics in situ IR spectroscopy kinetic isotope effect

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Relationship between heavy metal concentrations of herbaceous plants and soils at four Pb-Zn mining sites

Yuan LI , Yanqun ZU , Qixian FANG , Zhaohua GAO , Christian SCHVARTZ ,

《环境科学与工程前沿（英文）》 2009年第3卷第3期页码 325-333 doi: 10.1007/s11783-009-0024-5

摘要： This paper studied the relationship between heavy metal concentrations of herbaceous plants and soils at four Pb-Zn mining sites in Yunnan, China. 50 herbaceous plant samples of 9 plant species from 4 families and 50 soil samples were collected and then ana1yzed for the tota1 concentrations of Pb, Cd, and Zn. The results showed that the average concentrations of Pb, Cd, and Zn in soil samples were 3772.83, 168.81, and 5385.65 mg/kg, respectively. The average concentrations of Pb, Cd, and Zn were 395.68, 28.14, and 1664.20 mg/kg in the shoots, and 924.12, 57.25 , and 1778.75 mg/kg in the roots, respectively. Heterospecific plants at the same site and conspecific plants at various sites had different average levels of Pb, Cd, and Zn, both in the shoots and the roots. Enrichment coefficients of Pb, Cd, and Zn were greater than 1 in 2, 3, and 9 herbaceous plant samples, respectively. Translocation factors of Pb, Cd, and Zn were greater than 1 in 10, 17, and 25 herbaceous plant samples, respectively. In all 50 samples, the concentrations of Pb, Cd, and Zn between the shoots and the roots, the shoots, and the soils, and the roots and the soils had significant positive relationships.

关键词： Pb Cd Zn herbaceous plants Pb-Zn mining areas enrichment coefficient translocation factor

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Effect of noble metal nanoparticle size on C–N bond cleavage performance in hydrodenitrogenation: a studyof active sites

《化学科学与工程前沿（英文）》 2023年第17卷第12期页码 1986-2000 doi: 10.1007/s11705-023-2337-5

摘要： Breakage of the C–N bond is a structure sensitive process, and the catalyst size significantly affects its activity. On the active metal nanoparticle scale, the role of catalyst size in C–N bond cleavage has not been clearly elucidated. So, Ru catalysts with variable nanoparticle sizes were obtained by modulating the reduction temperature, and the catalytic activity was evaluated using 1,2,3,4-tetrahydroquinoline and o-propylaniline with different C–N bond hybridization patterns as reactants. Results showed a 13 times higher reaction rate for sp³-hybridized C–N bond cleavage than sp²-hybridized C–N bond cleavage, while the reaction rate tended to increase first and then decrease as the catalyst nanoparticle size increased. Different concentrations of terrace, step, and corner sites were found in different sizes of Ru nanoparticles. The relationship between catalytic site variation and C–N bond cleavage activity was further investigated by calculating the turnover frequency values for each site. This analysis indicates that the variation of different sites on the catalyst is the intrinsic factor of the size dependence of C–N bond cleavage activity, and the step atoms are the active sites for the C–N bond cleavage. When Ru nanoparticles are smaller than 1.9 nm, they have a strong adsorption effect on the reactants, which will affect the catalytic performance of the Ru catalyst. Furthermore, these findings were also confirmed on other metallic Pd/Pt catalysts. The role of step sites in C–N bond cleavage was proposed using the density function theory calculations. The reactants have stronger adsorption energies on the step atoms, and step atoms have d-band center nearer to the Fermi level. In this case, the interaction with the reactant is stronger, which is beneficial for activating the C–N bond of the reactant.

关键词： sp³/sp²-hybridized C–N bond noble metal nanoparticle catalytic active site turnover frequency DFT

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metals, polybrominated diphenyl ethers, and polychlorinated dibenzo-dioxins/furans at e-waste recycling sites

《环境科学与工程前沿（英文）》 2023年第17卷第7期 doi: 10.1007/s11783-023-1679-z

摘要：

● Heavy metals and organic toxins may persist in legacy sites for a long time.

关键词： E-waste Human health risk Organ risk Heavy metal toxicity PBDE PCDD/F

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Dual-functional sites for synergistic adsorption of Cr(VI) and Sb(V) by polyaniline-TiO hydrate: Adsorptionbehaviors, sites and mechanisms

《环境科学与工程前沿（英文）》 2022年第16卷第8期 doi: 10.1007/s11783-022-1526-7

摘要：

• PANI/Ti(OH)_n⁽⁴^–ⁿ⁾⁺ exhibited excellent adsorption capacity and reusability.

关键词： Polyaniline/TiO₂ Chromium Antimony Adsorption Desorption Mechanism

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Evaluation of the wind energy potential of two south west sites in Nigeria

Olaleye M. AMOO

《能源前沿（英文）》 2012年第6卷第3期页码 237-246 doi: 10.1007/s11708-012-0201-2

摘要： Wind resource assessment is a crucial first step in gauging the potential of a site to produce energy from wind turbines. In this paper, the wind energy potential of Abeokuta (07°03'N, 03°19'E) and Ijebu-Ode (06°47'N, 03°58'E), two south west sites in Nigeria were examined. Twenty years (1990–2010) of monthly mean wind data from a 10 m height were subjected to two-parameter Weibull analysis and other statistical analyses. The results show that the average annual mean wind speed variation for Abeokuta ranges from 2.2 to 5.0 m/s. For Ijebu-Ode, it ranges from 2.0 to 5.0 m/s. The wind power density variation based on the Weibull analysis ranges from 4.26 to 24.51 W/m for Abeokuta and from 8.54 to 76.46 W/m for Ijebu-Ode. Ijebu-Ode was found to be the better of the two sites in terms of annual variation of mean wind speed.

关键词： wind potential wind speed wind power density wind gust turbulence intensity Nigeria

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Design and analyses of open-ended pipe piles in cohesionless soils

Yuan GUO,Xiong (Bill) YU

《结构与土木工程前沿（英文）》 2016年第10卷第1期页码 22-29 doi: 10.1007/s11709-016-0314-5

摘要： Large open-ended pipe pile has been found to be advantageous for use in transportation projects. The current design method, however, is not adequately developed. To close this practice gap, this paper first summarized different design methods for open-ended pipe piles in sandy soils. A major factor for all the design codes is to properly account for the formation and effects of soil plug. The comparison indicates that there is a large variation in the base capacity evaluation among different methods due to the complex behaviors of soil plug. To close the knowledge gap, discrete element method (DEM) was used to simulate the soil plugging process and provide insight on the plugging mechanism. The simulation results show that the arching effect significantly increases the internal unit shear resistance along pipe piles. The porosity distribution and particle contact force distribution from DEM model indicate a large stress concentration occurs at the bottom of the soil plug. Besides, nearly 90% of the plug resistance is provided by the bottom half portion of the soil column. The soil-pile friction coefficient has a significant effect on the magnitude of plug resistance, with the major transition occurred for friction coefficient between 0.3 and 0.4.

关键词： open-ended pipe pile soil plug DEM base capacity

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Microwave-induced high-energy sites and targeted energy transition promising for efficient energy deployment

《能源前沿（英文）》 2022年第16卷第6期页码 931-942 doi: 10.1007/s11708-021-0771-y

摘要： Diverse interactions between microwaves and irradiated media provide a solid foundation for identifying novel organization pathways for energy flow. In this study, a high-energy-site phenomenon and targeted-energy transition mechanism were identified in a particular microwave heating (MH) process. Intense discharges were observed when microwaves were imposed on irregularly sized SiC particles, producing tremendous heat that was 8-fold the amount generated in the discharge-free case. Energy efficiency was thereby greatly improved in the electricity-microwaves-effective heat transition. Meanwhile, the dispersed microwave field energy concentrated in small sites, where local temperatures could reach 2000°C– 4000°C, with the energy density reaching up to 4.0 × 10⁵ W/kg. This can be called a high-energy site phenomenon which could induce further processes or reactions enhancement by coupling effects of heat, light, and plasma. The whole process, including microwave energy concentration and intense site-energy release, shapes a targeted-energy transition mechanism that can be optimized in a controlled manner through morphology design. In particular, the discharge intensity, frequency, and high-energy sites were strengthened through the fabrication of sharp nano/microstructures, conferring twice the energy efficiency of untreated metal wires. The microwave-induced high-energy sites and targeted energy transition provide an important pathway for high-efficiency energy deployment and may lead to promising applications.

关键词： microwave discharge high-energy sites targeted-energy transition morphology design energy efficiency

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Thermal response of steel framing members in open car park fires

Xia YAN; Marion CHARLIER; Thomas GERNAY

《结构与土木工程前沿（英文）》 2022年第16卷第9期页码 1071-1088 doi: 10.1007/s11709-022-0879-0

摘要： For open car park structures, adopting a performance-based structural fire design is often justified and allowed because the fire does not reach flashover. However, this design approach requires an accurate assessment of temperatures in structural members exposed to car fires. This paper describes a numerical study on the thermal exposure on steel framing members in open car park fires. Steel temperatures are computed by the coupling of computational fluid dynamics and finite element modeling, and by analytical models from the Eurocodes. In addition, the influence of galvanization on the steel temperature evolution is assessed. Results show that temperatures in unprotected beams and columns are influenced by the section geometry, car fire scenario, modeling approach, and use of galvanization. Galvanization slightly delays and reduces peak temperature. Regarding the different models, CFD-FEM (CFD: computational fluid dynamics, FEM: finite-element method) coupled models predict lower temperatures than the Hasemi model, because the latter conservatively assumes that the fire flame continuously touches the ceiling. Further, the Hasemi model cannot account for the effect of reduced emissivity from galvanization on the absorbed heat flux. Detailed temperature distributions obtained in the steel members can be used to complete efficient structural fire designs based on the member sections, structure layout, and use of galvanization.

关键词： open car park localized fire steel frame numerical modeling computational fluid dynamics

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Scale study of sites and pavilions for World Expo 2010

ZHOU Zhuoyan, CHEN Yi

《结构与土木工程前沿（英文）》 2008年第2卷第1期页码 102-106 doi: 10.1007/s11709-008-0012-z

摘要： The scale of sites and pavilions for World Expo 2010 (Shanghai World Expo) mainly refers to the study of their size including the area and number of exhibition hall needed in each pavilion and site with appropriate waiting area. All the design data of scale studied should reasonably meet the requirements during World Expo 2010 to accommodate large number of people for visiting and waiting to the full.

关键词： pavilion study number appropriate design

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NC flame pipe cutting machine tool based on open architecture CNC system

Xiaogen NIE, Yanbing LIU

《机械工程前沿（英文）》 2009年第4卷第2期页码 147-152 doi: 10.1007/s11465-009-0025-x

摘要： Based on the analysis of the principle and flame movement of a pipe cutting machine tool, a retrofit NC flame pipe cutting machine tool (NFPCM) that can meet the demands of cutting various pipes is proposed. The paper deals with the design and implementation of an open architecture CNC system for the NFPCM, many of whose aspects are similar to milling machines; however, different from their machining processes and control strategies. The paper emphasizes on the NC system structure and the method for directly creating the NC file according to the cutting type and parameters. Further, the paper develops the program and sets up the open and module NC system.

关键词： flame pipe cutting flame incision tracks CNC open architecture CNC system

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Cavitation in semi-open centrifugal impellers for a miniature pump

LUO Xianwu, LIU Shuhong, ZHANG Yao, XU Hongyuan

《能源前沿（英文）》 2008年第2卷第1期页码 31-35 doi: 10.1007/s11708-008-0011-8

摘要： Cavitation in miniature pumps was investigated experimentally for two semi-open centrifugal impellers. Although both impellers had the same blade cross-section, one impeller had a two-dimensional blade, while the other had a leaned blade. The flows were also analyzed using a numerical model of the three-dimensional turbulent flow in the pumps near the peak efficiency point using the -? turbulence model and the VOF cavitation model. The average cavitation performance of each impeller was satisfactorily predicted by the numerical simulations. The results show that the miniature pumps have similar cavitation performances as an ordinary-size pump, with the cavitation performance of the semi-open impeller reduced by increased axial tip clearances. Also, both the hydraulic and cavitation performance of the semi-open impeller were improved by the leaned blade. The results also show that uniform flow upstream of the impeller inlet will improve the cavitation performance of a miniature pump.

关键词： cavitation performance semi-open impeller increased two-dimensional efficiency