研究目的:地震会导致饱和砂土出现液化现象,从而使得地基失去承载力,造成建筑物产生不均匀沉降.我国现行《建筑抗震设计规范》(2016版)(GB 50011-2010)(以下简称《建筑抗规》)以标准贯入试验作为判别方法,采用液化指数将地基液化程度划分为三级.美国国家地震研究中心也提出了基于贯入度试验数据评估土体液化的方法,但没有液化等级这一综合性判定地基液化程度的指标,缺乏一定的实用性.本文结合孟加拉铁路工程项目实例,分别对砂土液化区域进行取样,并就同一批样品分别按中、美规范进行各土层液化判别试验,通过对比大量试验数据后,采用美标的评估数据建立适用于本工程的LPI(液化指数)表达式.研究结论:(1)从Idriss和Golesorkhi的地基土液化判定公式中,判定各土层液化综合考虑液化土层FS(抗液化安全系数)、液化土层厚度及液化土层深度、上覆有效应力等因素,为液化指数判定提供了一种思路;(2)目前中国《建筑抗规》对液化指数的计算结果偏于保守,考虑液化影响因素并不全面,需引入测试桩及上覆有效应力修正参数,对标准贯入锤击数基准值进行修正,才能得到与实际情况相结合的标准贯入锤击数临界值;(3)本文研究可应用于美规液化土壤判别试验数据,得到LPI(液化指数)与液化等级对应的表格,使得美抗规中提出的抗液化安全系数(FS)有了工程的实用性.

This paper presented underlying methylene blue (MB) color-fading mechanisms by photoluminescence-photocatalysis (PL-PC) reaction with PL materials coated with titanium dioxide (TiO2 ). The color fading mechanism means the photocatalytic degradation of organic dye by the coated TiO2 photocatalyst. The photocatalyst is activated by photoluminescent material. For PL materials, SrAl2 O4:Eu2+ ,Dy3+ (SAOED) and water resistant SAOED were selected for its long-lasting after-glow characteristics and well-known PL effect. All the tests were performed on a solution basis. The TiO2 coating played an important role in the subsequent MB color-fading reactions as revealed by a comparative study performed in dark and white light conditions. The presented results also revealed that the MB color-fading reaction involves two major mechanisms. The first mechanism is adsorption by the hydrolysis product of SAOED, that is, Al(OH)(3). The second is photocatalytic degradation by the TiO2 coating layer activated by the photoluminescent light. These results revealed color-fading mechanisms by PL-PC, which have potential for mechanochromic sensing characteristics since the tested materials are known to have mechanoluminescence properties.

Two different heteroelement-rich molecules have been successfully grafted on graphene oxide (GO) sheets which were then used as lubricant additives in bio-ionic liquid. The grafting was processed with reactions between GO sheets and synthesized heteroelement-rich molecules (Imidazol-1-yl phosphonic dichloride and 1H-1,2,4-triazol-1-yl phosphonic dichloride, respectively). The modified GO (m-GO) was added into [Choline][Proline] ([CH][P]) bio-ionic liquid, and has been demonstrated effective additive in promoting lubrication. Different characterization techniques have been utilized to study the reaction between GO and the two modifiers. The effect of molecular structure of the modifiers on the rheological and tribological properties of m-GO/[CH][P] lubricants was systematically investigated. Both theoretical calculation and experimental results demonstrated that the introduced heteroelement-rich groups are beneficial to increase the robustness of lubrication film by intensified hydrogen bonding and enhance the lubricant/friction surface adhesion by increased polarity of the m-GO. As a result, the interfacial lubrication could be significantly improved by these newly developed m-GO/[CH][P] lubricants.

Hierarchically porous carbon adsorbents were successfully fabricated from different biomass resources (softwood, hardwood, bamboo and cotton) by a facile two-step process, i.e. carbonization in nitrogen and thermal oxidation in air. Without involving any toxic/corrosive chemicals, large surface area of up to 890 m2/g was achieved, which is comparable to commercial activated carbon. The porous carbons with various surface area and pore size were used as adsorbents to investigate the pore size dependent adsorption phenomenon. Based on the density functional theory, effective (E-SSA) and ineffective surface area (InE-SSA) was calculated considering the geometry of used probing adsorbate. It was demonstrated that the adsorption capacity strongly depends on E-SSA instead of total surface area. Moreover, a regression model was developed to quantify the adsorption capacities contributed from E-SSA and InE-SSA, respectively. The applicability of this model has been verified by satisfactory prediction results on porous carbons prepared in this work as well as commercial activated carbon. Revealing the pore size dependent adsorption behavior in these biomass derived porous carbon adsorbents will help to design more effective materials (either from biomass or other carbon resources) targeting to specific adsorption applications.

Cotton fabric has been processed into hierarchically porous carbon with a two-step chemical-free method, i.e. carbonization in nitrogen and controlled thermal oxidation in air. By optimizing thermal oxidation temperature, large surface area of 777 m(2)/g could be achieved in cotton fabric derived carbon. The processed carbon remained the micron-meter tubular structure (same as cotton fiber), while meso-/micro-pores were also generated on tube wall. This uniquely structured porous carbon was then doped with nitrogen via a thermal pyrolysis process by using melamine as nitrogen source. The nitrogen doping level was controlled by adjusting the mass ratio of melamine and porous carbon. The nitrogen content in the doped porous carbon could reach up to 9.0 atom% without sacrificing the porous structure and surface area. The nitrogen doping significantly improved the electrochemical capacitance up to 180 F/g at 0.5 A/g, which is 74% enhancement compared to the nitrogen-free carbon (104 F/g). Both origin carbon and nitrogen doped carbon show excellent cycling stability that 95% of the capacitance could be remained after 5000 charge-discharge cycles. (C) 2016 Elsevier Ltd. All rights reserved.

Erosion is relevant to a variety of infrastructure problems such as bridge scour, roadway shoulder erosion, coastal erosion, and riverbank and slope stability. This research investigated the feasibility of using microbialinduced calcite precipitation (MICP) as an erosion countermeasure. MICP is a natural phenomenon in which calcite precipitation occurs as a consequence of microbial metabolic activity. The precipitated calcite modifies the soil fabric and provides an additional bonding force between soil particles. In this paper, a preliminary experimental study on the erosional behavior of MICP-treated sand is presented. A standard soil, Ottawa graded sand, was treated with a bacterium (Sporosarcina pasteurii) in a full-contact reactor-one in which the soil in a fabric mold was fully immersed in the bacteria and cementation solution. The morphologies and crystalline structures of the precipitated calcite in porous sediments were characterized using microscopic imaging techniques. The treated soil samples were tested in a flume to investigate the erosional behavior; both surface erosion and bridge scour tests were conducted. Although the untreated soil is highly erodible, the erosion of the treated sand was found to be negligible under the circumstances of the test; however, some concerns were raised regarding practical applications. Efforts will be made in the future to identify alternative treatment procedures that are more applicable to the field.

Phonon transfer is greatly scattered in traditional polymer composites due to the unpaired phonon frequency at the polymer/filler interface. A key innovation of this work is to build continuous crystal network by self-organization and utilize it as "thermal highway" that circumvents the long-existing interfacial thermal barrier issue in traditional composites. By tuning the molecular diffusion rate of dicarboxylic acids (oxalic acid, malonic acid, and succinic acid), different crystal structures including skeletal, dendrite, diffusion-limited aggregates, and spherulite were synthesized in PVA film. These continuous crystal structures benefit the efficient phonon transfer in the composites with minimized interfacial scattering and lead to a significant thermal conductivity enhancement of up to 180% compared to that of pure polymer. Moreover, the transparent feature of these composite films provides additional benefits in display applications. The post heat treatment effect on the thermal conductivity of the composite films shows a time-dependent behavior. These uniquely structured polymer/crystal composites are expected to generate significant impacts in thermal management applications.

Four different plant biomass, bamboo, cotton, soft wood and hard wood, were utilized as carbon precursors to fabricate porous carbon catalyst supports via a chemical free approach. Large surface area with unique mesoporous structure was successfully created in the carbon, which made them suitable for catalyst support. After decorating silver nanoparticles onto these carbon supports, nitroaromatics reduction reactions were performed to evaluate the catalyst activity. Results indicate that chemical composition and surface groups of carbon supports determine the metal catalyst nucleation/growth while the porous microstructure of support affects the mass transport of reactant/product across the liquid/catalyst interface. Among the four selected biomass, porous carbon manufactured from soft wood acquires the highest average pore size, pore volume, mesopore volume fraction and best catalytic activity after decorating silver nanoparticles. This work not only presents an environmental benign process that converts natural biomass into effective porous carbon catalyst supports, but also offers a comprehensive understanding of biomass structure/composition relating to their suitability as catalyst support.

Hybrid electrodes with electroactive components on conductive substrates have been demonstrated to be an effective strategy to achieve high energy and power density in supercapacitors. However, the mismatch of interface property could be a huge hurdle to further improve energy storage performance and long-term stability. In this work, an interfacial metal seeding approach has been developed targeting strengthening of the interfacial interaction between electroactive NiCo2O4 nanostructure and carbon substrate as well as to promote electron transfer across the interface. By implanting low-concentration nickel (Ni) nanoparticles at the interface, the electrochemical capacitance of NiCo2O4 was boosted up to 2367 F/g at a current density of 1 A/g in a symmetric two-electrode configuration, which is about 2 times higher than the capacitance obtained from the electrode without metal seeds. The Ni seeds also contribute to an excellent cycling retention of >96% after 5000 cycles, where only 65% capacitance was retained in the electrode without Ni seeds. A synergistic contribution of promoted interfacial interaction, reduced internal resistance, enlarged surface area, and mesoporous NiCo2O4 nanorod structure leads to a boosted energy efficiency of NiCo2O4 in this study. A comparative study on different metal nanoparticles (nickel, cobalt, and iron) reveals that not only metal species but also particle concentration play significant roles in determining the energy storage property of the hierarchical NiCo2O4/carbon electrodes.

Superamphiphobic and electroactive composite coating on aluminum substrate was successfully fabricated by integrating epoxy, polyaniline (PANI), fluorinated ethylene propylene, carbon nanotubes and SiO2 nanoparticles into a two-layer coating configuration with nano/micro hierarchical surface structure. The composite coating demonstrates strong adhesion, excellent wear resistance and durable anti-wettability. The electrochemical tests demonstrated significantly enhanced anticorrosion performance by surface barrier effect of the superamphiphobic coating and redox catalytic capability of embedded electroactive PANI. The design principle of the multi-functional coatings will definitely benefit the advancement of durable anti-corrosive coatings and the achieved superior properties will promise a wider engineering applications in petroleum related industries.

Alcohols (methanol, ethanol and isopropanol) have been found to affect the heterogeneous nucleation and growth of Ag nanoparticles onto oxygenated mesoporous carbon support and the corresponding catalytic property of Ag/Carbon nanocomposite in nitroaromatics (4-nitrophenol and 2-nitroaniline) reduction reactions. Ethanol exhibits unique capability to regenerate reactive CH2OH groups on carbon surface and successfully control Ag particle size through extending the nucleation process. Catalyst prepared with ethanol shows well-controlled particle size and dispersion and thus the highest catalytic activity in reduction reactions. The mechanism of catalyst structure control by alcohols is also investigated in this work.

Depolymerization and modification of lignin have been achieved simultaneously in a one-pot chemical reaction. Two heteroelement-rich modifiers, imidazol-1-yl phosphonic dichloride and 1H-1,2,4-triazol-1-yl phosphonic dichloride, were selected to react with lignin in this work. The modified lignin (m-lignin) is demonstrated as an effective lubricating additive for [choline][amino acid] ([CH][AA]) bioionic liquids. Different characterization techniques have been utilized to study the lignin depolymerization, reaction between lignin and modifiers and m-lignin/[CH][AA] interaction. The effect of the molecular structure of the modifiers on the rheological and tribological properties of m-lignin/[CH] [AA] lubricants was systematically investigated. Density function theory is used to calculate the electronic structure of lignin, m-lignin, and [CH][AA]. The atomic natural charge analysis revealed the most negative charge on nitrogen bonded to a phosphorus atom and the strongest capability of forming hydrogen bonding with [CH][AA]. The introduced nitrogen and phosphorus elements not only increase the hydrogen bonding density in m-lignin/[CH][AA] but also enhance the polarity of the m-lignin, both of which facilitate a strong adhesion of lubricant on a metal surface and thus promote lubrication. A larger fraction of heteroatom groups in m-lignin contributes to a better lubrication property of these lubricants.

Ionic liquid lubricants or lubricant additives have been studied intensively over past decades. However, ionic grease serving as lubricant has rarely been investigated so far. In this work, novel protic [triethanolamine][oleic acid] and aprotic [choline][oleic acid] ionic greases are successfully synthesized. These ionic greases can be directly used as lubricants without adding thickeners or other additives. Their distinct thermal and rheological properties are investigated and are well-correlated to their tribological properties. It is revealed that aprotic ionic grease shows superior temperature- and pressure-tolerant lubrication properties over those of protic ionic grease. The lubrication mechanism is studied, and it reveals that strong physical adsorption of ionic grease onto friction surface plays a dominating role for promoted lubrication instead of tribo-chemical film formation.

Mesoporous carbon with embedded iron carbide nanoparticles was successfully synthesized via a facile impregnation-carbonization method. A green biomass resource, cotton fabric, was used as a carbon precursor and an iron precursor was implanted to create mesopores through a catalytic graphitization reaction. The pore structure of the nanocomposites can be tuned by adjusting the iron precursor loadings and the embedded iron carbide nanoparticles serve as an active component for magnetic separation after adsorption. The microstructure of the nanocomposites was carefully investigated by various characterization techniques including electron microscopy, X-ray diffraction, surface analyzer, magnetic property analyzer and etc. The newly created mesopores are demonstrated as a critical component to enhance the adsorption capacity of organic dyes and embedded iron carbide nanoparticles are responsible for the selective removal of heavy metal ions (Zn2+, Cu2+, Ni2+, Cr6+ and Pb2+). Isotherm adsorption, kinetic study at three different temperatures (25, 45 and 65 degrees C) and cycling retention tests were performed to understand the adsorptive behavior of the nanocomposites with organic dyes (methylene blue and methyl orange). Together with the preferable removal of more toxic heavy metal species (Cr6+ and Pb2+), these mesoporous nanocomposites show promising applications in pollutant removal from water. The facile material preparation allows convenient scale-up manufacturing with low cost and minimum environmental impact.

A chemical-free method is developed to convert cotton fabric into reactive mesoporous carbon via optimized carbonization and oxidation processes. The processed carbon serves as both catalyst support and reactant which controls the nucleation/growth of Ag nanoparticles. The particle size is successfully controlled below 5 nm with mono-dispersion on carbon support. Various characterization techniques including scanning/transmission electron microscopies, N-2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectrum are used to study the evolution of carbon support microstructure and surface composition during thermal oxidation as well as the in-situ reaction between carbon support and Ag precursor during hybridization. These Ag/carbon catalysts, with well-controlled Ag nanoparticle size and excellent dispersion, out-perform other existing catalysts reported from literature in terms of activity and stability. The unique property of these catalysts promises potential applications in other chemical reactions besides the demonstrated capability in nitroaromatics reduction. Moreover, this green technology of processing biomass into effective catalyst support provides a great platform to design metal/carbon hybrid catalysts from wider biomass resources and target to broader catalytic reactions. (C) 2015 Elsevier B.V. All rights reserved.

Converting nitrobenzene to freestanding polyaniline tube arrays has been successfully carried out in a "water-oil-water" triphasic reaction system, where catalytic reduction of nitrobenzene to aniline and aniline polymerization reactions were synergistically integrated. With optimized control over molecular diffusion and reaction at separate solid/liquid and liquid/liquid interfaces, polyaniline nanostructures could be synthesized with different morphologies. The paired molecular diffusion and reaction rate is revealed as the dominating factor that determines the feasibility of the reaction system to produce a patterned array structure. Slow molecular diffusion leads to a better ordered three-dimensional (3D) assembling structure. This work demonstrates a new approach to control 3D assembling structures with integrated control on diffusion and reaction across multiple liquid/liquid interfaces.

Freestanding conductive polymer tube arrays can be synthesized by synergistically integrating diffusion and reaction control at separate liquid/liquid interfaces without using substrates or templates.

A novel micelle-mediated phase transfer method is developed to synthesize hollow polyaniline spheres with mesoporous brain-like convex-fold shell textures. High superhydrophobicity is achieved due to the highly ordered porous structures and low surface energy provided by perfluorooctanoic acid.

Perovskite hybrid solar cells (pero-HSCs) have been intensively investigated due to their promising photovoltaic performance. However, the correlations between the efficiencies of pero-HSCs and thin film thicknesses and morphologies of CH3NH3PbI3−xClx perovskite layers are rarely addressed. In this study, we report the correlation between the efficiencies of “planar heterojunction” (PHJ) pero-HSCs and the thin film thicknesses and morphologies of solution-processed CH3NH3PbI3−xClx perovskite layers. Investigation of absorption spectra, X-ray diffraction patterns, atomic force microscopy and scanning electron microscopy images of CH3NH3PbI3−xClx layers indicate that the efficiencies of PHJ pero-HSCs are dependent on the film thickness, as the thickness of CH3NH3PbI3−xClx is less than 400nm; whereas the efficiencies are significantly dependent on the film morphologies of CH3NH3PbI3−xClx layers as the thickness is larger than 400nm. Our studies provide a promising pathway for fabricating high efficiency PHJ pero-HSCs.