Study on Hydrothermal Stability and Catalytic Activity of Al-SBA-15 Mesoporous Materials Prepared by Impregnation Method

The mesoporous Al-SBA-15 zeolite was obtained via impregnation of pure silica-based SBA-15 zeolite with aluminum nitrate.The Al-SBA-15 sample was calcined in air at 800 ℃ for 6 h and hydrothermally treated at near 100 ℃ for 120 h,respectively,and then the thermal and hydrothermal stability of Al-SBA-15 sample was investigated by X-ray diffractometry (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM) and nitrogen adsorption and desorption techniques.The Al-SBA-15 sample was also studied by 27 Al nuclear magnetic resonance (27 Al NMR) and ammonia temperature programmed desorption (NH 3-TPD) techniques.In addition,the catalytic activity of Al-SBA-15 zeolite was investigated by the Friedel-Crafts reactions of 2,4-di-tert-butylphenol with cinnamyl alcohol.The test results showed that the thermal and hydrothermal stability of Al-SBA-15 zeolite was better than that of SBA-15 zeo-lite.The Al-SBA-15 zeolite sample prepared by impregnation method exhibits more framework aluminum species and Al-O-Si units.Therefore,the number of the surface hydroxyl groups was reduced,resulting in the stabilization of framework structure ofAl-SBA-15 zeolite.The aluminum species can form weak and medium-strong acid sites with catalytic activity.

Site selection of emergency material warehouse under fuzzy environment

The objective of this work was to determine the location of emergency material warehouses. For the site selection problem of emergency material warehouses, the triangular fuzzy numbers are respectively demand of the demand node, the distance between the warehouse and demand node and the cost of the warehouse, a bi-objective programming model was established with minimum total cost of the system and minimum distance between the selected emergency material warehouses and the demand node. Using the theories of fuzzy numbers, the fuzzy programming model was transformed into a determinate bi-objective mixed integer programming model and a heuristic algorithm for this model was designed. Then, the algorithm was proven to be feasible and effective through a numerical example. Analysis results show that the location of emergency material warehouse depends heavily on the values of degree a and weight wl. Accurate information of a certain emergency activity should be collected before making the decision.

Rational design of stratified material with spatially separated catalytic sites as an efficient overall water-splitting photocatalyst

The development of metal sulfide catalysts with remarkable activity toward efficient overall photocatalytic water splitting remains challenging owing to the dominant charge recombination and deficient catalytic active sites.Moreover,in the process of water oxidation catalysis,the inhibition of severe photocorrosion is an immense task,requiring effective photogenic hole-transfer kinetics.Herein,stratified Co-MnO_(2)@CdS/CoS hollow cubes with spatially separated catalytic sites were rationally designed and fabricated as highly efficient controllable catalysts for photocatalytic overall water splitting.The unique self-templated method,including a continuous anion/cation-exchange reaction,integrates a Co-doped oxidation co-catalyst(Co-MnO_(2))and a reduction co-catalyst(CoS)on the nanocubes with uniform interface contact and ultrathin two-dimensional(2D)nanometer sheets.We demonstrate that the stratified Co-MnO_(2)@CdS/CoS hollow cubes can provide an abundance of active sites for surface redox reactions and contribute to the separation and migration of the photoionization charge carriers.In particular,CoS nanoparticles dispersed on the walls of CdS hollow cubes were identified as reduction co-catalysts accelerating hydrogen generation,while Co-MnO_(2) nanosheets attached to the inner walls of the CdS hollow cube were oxidation co-catalysts,promoting oxygen evolution dynamics.Benefiting from the desirable structural and compositional advantages,optimized stratification of Co-MnO_(2)@CdS/CoS nanocubes provided a catalytic system devoid of precious metals,which exhibited a remarkable overall photocatalytic water-splitting rate(735.4(H_(2))and 361.1(O_(2))μmol h^(−1) g^(−1)),being among the highest values reported thus far for CdS-based catalysts.Moreover,an apparent quantum efficiency(AQE)of 1.32%was achieved for hydrogen evolution at 420 nm.This study emphasizes the importance of rational design on the structure and composition of photocatalysts for overall water splitting.

A new inorganic-organic hybrid material as consolidation material for Jinsha archaeological site of Chengdu

An organic-inorganic epoxy-silica-acrylate(ESA) hybrid material was used for the consolidation of Jinsha archaeological site of Chengdu in China.The hybrid materials have multiple functional groups,such as anhydride,epoxy,hydroxyl and carboxyl,which can form networks at room temperature and result in an enhanced chemical and water resistance of the consolidated soil.With increasing of TEOS content,the hybrid materials keep colorless with only some reduction of transparency,while the hybrid materials obviously turn from moderate yellowish to brown yellow with the increase of the epoxy resin(EOR) content after 120 min UV irradiation.SEM observation indicates that the hybrid soil consolidation materials can effectively penetrate into the soil substrate,fill up most of the pores,decrease the area porosity and consolidate the Jinsha archaeological soil.The consolidation performances are in the sequence:ESA > K2SiO4(PS) > tetraethyl orthosilicate(TEOS).

Coseismic site response and slope instability using periodic boundary conditions in the material point method

This paper proposed the explicit generalized-a time scheme and periodic boundary conditions in the material point method(MPM)for the simulation of coseismic site response.The proposed boundary condition uses an intuitive particle-relocation algorithm ensuring material points always remain within the computational mesh.The explicit generalized-a time scheme was implemented in MPM to enable the damping of spurious high frequency oscillations.Firstly,the MPM was verified against finite element method(FEM).Secondly,ability of the MPM in capturing the analytical transfer function was investigated.Thirdly,a symmetric embankment was adopted to investigate the effects of ground motion arias intensity(I_(a)),geometry dimensions,and constitutive models.The results show that the larger the model size,the higher the crest runout and settlement for the same ground motion.When using a Mohr-Coulomb model,the crest runout increases with increasing I_(a).However,if the strain-softening law is activated,the results are less influenced by the ground motion.Finally,the MPM results were compared with the Newmark sliding block solution.The simplified analysis herein highlights the capabilities of MPM to capture the full deformation process for earthquake engineering applications,the importance of geometry characterization,and the selection of appropriate constitutive models when simulating coseismic site response and subsequent large deformations.

Swelling Properties of Water-Swelling Materials Exposed to Organic Water Pollution

A water-swelling material is one of the rubbery impermeable materials which mixed synthetic resin elastomers as a base material, high absorbency polymers, filler and solvents. In this study, swelling characteristics of the water-swelling material on the water polluted with COD and BOD, as an impermeable material at coastal landfill sites, are examined by laboratory swelling ratio test. Furthermore, the factor in which it influences the swelling pressure of water-swelling material is clarified by measuring the swelling pressure. As the results, the COD nor the BOD concentrations in the soaked water influence the swelling ratio of the water-swelling material. When the thicknesses of water-swelling material are 2 mm and 3 mm, the maximum swelling pressure of 0.5 MPa or more that corresponds to hydraulic pressure by depth of 50 m is possessed.

大跨径悬索桥主缆线形影响因素分析

为提高大跨径悬索桥主缆线形的架设精度,以深中通道深中大桥为背景,进行主缆线形影响因素分析。根据国内外已建桥梁的实测数据,分析现有工艺技术条件下主缆实际制索精度;采用BNLAS软件建立该桥有限元模型,从材料参数和现场施工两方面分析主缆弹性模量、索股自重、温度及桥塔偏位对主缆线形的影响,计算各因素对主缆空缆各跨跨中标高的影响系数。结果表明:现有工艺条件下的制索精度无法满足标记点对位架设的精度要求;主缆弹性模量、索股自重、温度及桥塔偏位对各跨主缆线形有不同程度的影响,主缆弹性模量偏大时,各跨线形偏低,对中跨跨中标高的影响系数约为-0.1100 m/%;索股自重偏大时,中跨跨中标高偏低,影响系数约为-0.0941 m/(kN·m);温度越低,跨中标高越高,对中跨跨中标高的影响系数约为-6.266 cm/℃;桥塔纵向偏向某跨时,该跨线形偏低,桥塔塔顶标高变高时,相邻两跨线形偏高。

道孚抽水蓄能电站施工总布置规划

四川省道孚抽水蓄能电站上水库海拔约4300 m,为当前全球海拔最高的大型抽水蓄能电站,工程规模宏大,上、下水库高差大,下水库施工场地狭窄,施工布置难度大。为科学确定施工总布置规划方案,在分析工程施工特性、确定施工总布置规划原则的基础上,通过计算分析和方案比较,系统研究得到施工总布置分区、料场选择与规划、场内交通规划、主要施工工厂设施和施工营地、堆(存、转)场规划方面的主要设计成果。结果表明:推荐的施工总布置规划方案合理可行,符合工程实际特点,满足相关规程规范和政策的要求。研究成果可为类似高海拔工程提供借鉴。

Site quality evaluation of loblolly pine on the South Carolina Lower Coastal Plain,USA

Eleven soil types, which can be identified and delineated using conventional soil survey procedures, were characterized for loblolly pine （Pinus taeda L.） productivity. Four 4-hectare study sites, each containing four measurement plots, were established for every soil type studied. In a stepwise multiple regression, both soil parent material （i.e. a combination of subsoil texture and geology） （p〈0.001）, and drainage class （p=0.006） were significant predictors of site index （tree age 25）, and the overall linear regression model had an R2 value of 0.55. The extremes of soil parent material differed by 3.9 m site index （loamy subsoil on the Wicomico-Penholoway surfaces versus clayey subsoil on the Pamlico-Princess Anne surfaces）. Each increment of drainage class differed by 0.7 m site index. For example, a poorly drained soil had 0.7 m lower site index than a somewhat poorly drained soil. For seven of the eleven soil types studied, there is greater than 80% probability that estimated mean site index is within ±0.8 m of the actual soil type mean site index. The other four soil types （labeled G, I, C and K） need to be either redefined or sampled more intensively. Two of these need to be subdivided in order to adequately characterize site quality, one based on geology （Soil type G） and one based on soil drainage class （Soil type I）. Variation in soil drainage class and varying amounts of topsoil displaced into windrows were both factors influencing site quality variation of a third soil type （Soil type C）. The wide variation in site index data for a fourth soil type （Soil type K） appeared to be due, in part, to sampling study locations and individual measurement plots with less than optimum bedding and/or artificial drainage. Soil parent material （subsoil texture and geology） along with drainage class were found to be important factors influencing site quality on the South Carolina Lower Coastal Plain.

High-throughput computational screening of Cu-MOFs with open metal sites for efficient C_2H_2/C_2H_4 separation

Cost effective separation of acetylene(C_2H_2)and ethylene(C_2H_4)is of key importance to obtain essential chemical raw materials for polymer industry.Due to the low compression limit of C_2H_2,there is an urgent demand to develop suitable materials for efficiently separating the two gases under ambient conditions.In this paper,we provided a high-throughput screening strategy to study porous metal-organic frameworks(MOFs)containing open metal sites(OMS)for C_2H_2/C_2H_4 separation,followed by a rational design of novel MOFs in-silico.A set of accurate force fields was established from ab initio calculations to describe the critical role of OMS towards guest molecules.From a large-scale computational screening of 916 experimental Cu-paddlewheel-based MOFs,three materials were identified with excellent separation performance.The structure-performance relationships revealed that the optimal materials should have the largest cavity diameter around 5-10?and pore volume in-between 0.3-1.0 cm^3 g^(-1).Based on the systematic screening study result,three novel MOFs were further designed with the incorporation of fluorine functional group.The results showed that Cu-OMS and the-F group on the aromatic rings close to Cu sites could generate a synergistic effect on the preferential adsorption of C_2H_2 over C_2H_4,leading to a remarkable improvement of C_2H_2 separation performance of the materials.The findings could provide insight for future experimental design and synthesis of high-performance nanostructured materials for C_2H_2/C_2H_4 separation.

Transition metal-nitrogen sites for electrochemical carbon dioxide reduction reaction

Electrochemical CO2 reduction reaction(CO2RR)powered by renewable electricity has emerged as the most promising technique for CO2 conversion,making it possible to realize a carbon‐neutral cycle.Highly efficient,robust,and cost‐effective catalysts are highly demanded for the near‐future practical applications of CO2RR.Previous studies on atomically dispersed metal‐nitrogen(M‐Nx)sites constituted of earth abundant elements with maximum atom‐utilization efficiency have demonstrated their performance towards CO2RR.This review summarizes recent advances on a variety of M‐Nx sites‐containing transition metal‐centered macrocyclic complexes,metal organic frameworks,and M‐Nx‐doped carbon materials for efficient CO2RR,including both experimental and theoretical studies.The roles of metal centers,coordinated ligands,and conductive supports on the intrinsic activity and selectivity,together with the importance of reaction conditions for improved performance are discussed.The mechanisms of CO2RR over these M‐Nx‐containing materials are presented to provide useful guidance for the rational design of efficient catalysts towards CO2RR.

Preparation and Characterization of Novel Ti-doped M-site Deficient Olivine LiFePO_4

A novel Ti-doped M-site deficient olivine LiFePO4, i.e. Li0.95Fe0.95Ti0.05PO4, was synthesized by a solid-state reaction method. XRD and VTR were used to characterize the as-prepared samples. As a cathode material for lithium-ion batteries, Li0.95Fe0.95Ti0.05PO4 exhibited improved rate capability.

椰壳纤维加筋土遗址生态注浆材料的性能

为提升土遗址注浆料的力学性能,以椰壳纤维掺和糯米浆、烧料礓石以及黄土改性注浆料为研究对象,研究了椰壳纤维长度和掺量(质量分数)对土遗址注浆料流动性、收缩性、抗压强度和抗折强度的影响.结果表明:椰壳纤维的掺量和长度越大,浆体的流动性越低,而椰壳纤维的长度与浆体的收缩率无明显相关性;椰壳纤维良好的桥接能力可以有效提高浆体固化后的抗压强度、抗折强度和延性;椰壳纤维的长度和掺量均存在最优值,建议最优配比为纤维长度6 mm、掺量0.5%~0.6%,此时浆体固化后的抗压强度、抗折强度分别提升49.09%和32.08%;过多、过长的椰壳纤维易发生弯折、团聚,导致浆体的流动性和强度大幅降低.

泥河湾盆地东谷坨遗址2016-2019年发掘简报

泥河湾盆地内埋藏有诸多旧石器时代早期遗址,是研究古人类扩散、适应和技术演化的重要区域。东谷坨遗址位于泥河湾盆地的东缘,丰富的文化遗物为研究石器技术和人类行为提供了重要证据。在2016-2019年的发掘中,发掘团队将原来的6A-6E五个文化层进一步划为八个文化层,共出土编号石制品6800余件、化石4100余件。本文重点对6A2和6C1两个主要文化层的出土标本进行初步报道。石制品原料均以遗址周边分布的燧石为主,质量相对较高的石料被优选。锤击石核与石片、砸击石核均有发现;尝试石核和多面多向剥片的石核是主要类型。石器以刮削器为主,多为单刃。两个文化层的石制品类型与技术存在一定差异,如:6A2层石核转向频率更高、双刃石器比例更高,而6C1层锯齿刃器比例高于6A2层等,但总体上呈现了旧石器时代早期相对简单的剥片与加工模式。可鉴定动物化石种类不多,少量骨骼上有疑似人工砍砸的痕迹。本次发掘出土的材料为解释盆地内早更新世人类的石器技术和行为演化等提供了丰富的信息,同时也为理解早期人类对原料资源的利用方式、流动性组织等提供了重要素材。

图书馆史研究与编纂的历史逻辑

文章以历史观为出发点,在前人有关图书馆史研究与编纂研究的基础上,提出史料、史迹、史境、史脉、史识的历史逻辑理论;以中山大学图书馆百年馆史研究与编纂的实践为案例,从立足史料、呈现史迹、再现史境、传承史脉、端正史识五个方面系统阐释“五史”理论在实践中的具体运用,助益新时代图书馆史研究与图书馆史志编纂发展。

Characterization of A-site excessive perovskite La_(0.7-x)Sm_(x+0.02)Ca_(0.3)CrO_(3-δ)

La0.7-xSmx＋0.02Ca0.3CrO3-δ （0≤x≤0.4） powders with A-site excessive perovskite structure were synthesized by auto-ignition process and characterized. X-ray diffraction （XRD） patterns of samples after sintering at 1400℃ for 4 h were indexed as tetragonal structure. The relative densities were all above 96% although decreased slightly with the increasing content of samarium, indicating that the excessive A-site element was helpful to enhance their sinterability. Conductivities of the specimens in air increased with increasing content of samarium. The conductivity of La0.6Sm0.12Ca0.3CrO3_swas 33.6 S/cm in air at 700℃ which was about 1.7 times as high as that of La0.7Ca0.3CrO3-δ （20.1 S/cm）. Average thermal expansion coefficients （TECS） of the specimens increased from 11.06×10^-6 to 12.72×10^-6 K^-1 when x increased from 0 to 0.4, and they were close to that of Y doped ZrO2 （YSZ）.La0.7-xSmx＋0.02Ca0.3CrO3-δ （0.1≤x≤0.3） were good choices for intermediate temperature solid oxide fuel cells （IT-SOFCs） interconnect materials.

十六国、北朝长安城遗址出土建筑材料简论

十六国时期的前赵、前秦、后秦和北朝时期的西魏、北周都是利用汉长安故城营建新都,后赵也在长安城内做过较大规模的建设。本文利用十六国、北朝长安城遗址出土的建筑材料,参考其他遗址及墓葬资料,分别对长条砖、板瓦、筒瓦和瓦当进行了类型学研究,并对它们的时代做了推定。

智慧工地物料配送动态时间窗车辆路径优化

智慧工地物料配送是建筑业提升建造效率的重要环节。为有效解决智慧工地物料配送路径优化问题,依托运筹学理论将其转化为带时间窗的车辆路径规划问题。以总配送路径最短为目标函数,建立动态时间窗车辆路径(VRPDTW)数学模型,构建全局最优理论模型。运用改进人工势场算法分析障碍物和中间节点,再代入基础蚁群算法进行施工现场全局路径规划,对VRPDTW数学模型进行优化。并通过仿真实验对模型进行实证检验。结果表明:改进算法和VRPDTW模型可实现全局优化,能够有效解决智慧工地场景下物料连续配送问题,相较于基础算法,改进算法使路径规划的准确度提高,成本降低,效率提升,具有理论意义和行业应用价值。

铬污染场地固化/稳定化修复技术研究进展

固化/稳定化技术是当前国内、外处置重金属污染场地最常用的技术之一。固化/稳定化技术的药剂选择及施工工艺是影响最终修复效果的重要因素。通过综述铬污染场地的成因及固化/稳定化修复技术,重点从修复材料、施工工艺2个方面对修复铬污染场地的固化/稳定化技术研究进展进行总结;对比分析了不同修复材料的特性、作用原理、优缺点、适用性和不同施工工艺对修复效果的影响,并提出了未来发展和研究需求,为今后开展铬污染场地固化/稳定化修复工作提供一定借鉴。

油茶果皮基碳材料的制备及其在超级电容器中的应用研究

通过碳化和活化两步法将油茶果皮废弃物转化为生物质多孔碳材料,并探究其在超级电容器电极材料中的应用。结果表明,活化过程中碳/碱质量比和温度对碳材料的结构有很大影响,当碳/碱质量比为1∶3、活化温度为700℃时制得的碳材料具有最高的比表面积(2453 m^(2)/g)、最大孔容(1.08 cm^(3)/g)以及丰富的边缘缺陷位点。这些特性增加了电极的活性位点,促进了离子传输,进而表现出优异的电容性能(电流密度为1 A/g时质量比电容为382.1 F/g)以及优良的循环稳定性。