花岗岩残积土-土工格栅界面的后循环剪切行为研究

花岗岩残积土在华南、东南沿海、南岳、新疆等地区广泛分布,前人的研究多集中在结构性及微观特性上,后循环加载、位移演化、土壤密度等因素对筋-土界面的剪切特性及加筋作用效果的影响评估研究较少。从循环试验剪切刚度这一重要参数入手,以加载次数、加载频率值、位移振幅值、土壤重度值为自变量,应用控制变量法,通过设计循环直剪试验,得到加筋花岗岩残积土的剪切应力与剪切位移、垂直位移与剪切位移关系曲线进行观察对比,结果表明:花岗岩残积土土工格栅界面剪切刚度受位移半振幅、土壤干重度影响很大,受加载频率影响很小,循环加载并没有弱化后循环界面剪切强度,剪切位移与位移半振幅呈负相关关系。     

1-苯基-3-甲基-4-咔唑-N-丁基-4-苯甲酰基呲唑啉-5-酮的合成及其光谱研究

在苯和50％NaOH介质中，80℃时1，4-二溴丁烷与咔唑(CZ)反应，生成N-溴丁基咔唑(BCZ)。在丙酮和K2CO2介质中，50℃时N-溴丁基咔唑与1-苯基-3-甲基-4-苯甲酰基吡唑啉-5-酮(PMBP)反应，生成1-苯基-3-甲基-4-咔唑-N-丁基-4-苯甲酰基吡唑啉-5-酮(PMCBP)，详细研究了CZ，BCZ，PMBP和PMCBP的UV和IR光谱．在氯仿中PMCBP对Nd(Ⅲ)的萃取率是PMBP的2．3倍，PMBP-Nd(Ⅲ)配合物无荧光，但PMCBP-Nd(Ⅲ)配合物有很强的荧光，说明PM-CBP是Nd(Ⅲ)的优良荧光试剂。     

Electrical conductivity of polyblends of poly(1,4-phenylene vinylene) and poly(2,5-dimethoxy-1,4-phenylene vinylene)

Summary A series of polyblends of poly(1,4-phenylene vinylene), PPV, and poly(2,5-dimethoxy-1,4-phenylene vinylene), PDMPV, were prepared in film form from precursor polyblends of the respective sulfonium salt polymers, which were separately prepared from the respectivebis(sulfonium salt) monomers. The blend films were doped with I₂ at room temperature to obtain a wide range of electrical conductivities (10^–2 to 10²Scm^–1) depending on the blend composition. The higher the content of PDMPV in the blends the higher was the conductivity.     

Comparison of relative viscosity measurement of polyvinylpyrrolidone in water by glass capillary viscometer and differential dual‐capillary viscometer

The relative viscosity (RV) of polyvinylpyrrolidone (PVP) with different molecular weights was measured with a glass capillary viscometer and with a differential dual‐capillary viscometer in water at different concentrations. For the differential dual‐capillary viscometer, RV increases with a decreasing flow rate, especially for high molecular weight PVP at a 1% concentration. A good agreement in the RV between the two methods can be obtained for PVP with different molecular weights and at various concentrations if an appropriate flow rate is selected for the differential dual‐capillary viscometer. Special precaution is needed when using the differential dual‐capillary viscometer to measure the viscosity of a pure solvent. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1312–1315, 2002     

Preparation and properties of heterocyclically conjugated poly(3‐hexylthiophene)–clay nanocomposite materials

A series of heterocyclically conjugated polymer–clay nanocomposite (PCN) materials that consisted of organic poly(3‐hexylthiophene) (P3HT) and inorganic montmorillonite (MMT) clay platelets were prepared by in situ oxidative polymerization with FeCl₃ as an oxidant. The as‐synthesized PCN materials were characterized by Fourier transform infrared (FTIR) spectroscopy, wide‐angle powder X‐ray diffraction (WAXRD), and transmission electron microscopy (TEM). The effects of the material composition on the anticorrosion, gas barrier, thermal stability, flammability, mechanical strength, and electrical conductivity properties of the P3HT and PCN materials were studied by electrochemical corrosion measurements, gas‐permeability analysis (GPA), thermogrametric analysis (TGA), limiting oxygen index (LOI) measurements, dynamic mechanical analysis (DMA), and a four‐point probe technique, respectively. The molecular weights of extracted and bulk P3HT were determined by gel permeation chromatography (GPC) with THF as an eluant. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3438–3446, 2004     

Adsorption and desorption kinetics of hydrocarbons in FCC catalysts studied using a tapered element oscillating microbalance (TEOM). Part 2: numerical simulations

The factors affecting the adsorption and desorption kinetics in a TEOM are reviewed in detail with particular attention given to the assumptions required to obtain physical transport parameters from the data. Two models are presented to simulate TEOM adsorption data in the case that concentration differences down the catalyst bed can be neglected, as is appropriate when the amount of catalyst used is small, the carrier gas flowrate is large, and/or the adsorbate partial pressure is low. In the first model, the effective diffusion coefficient, D_e, is taken to be constant. In the second model, the effective diffusion coefficient is assumed to obey the Darken equation, D_e=D₀/(1−θ). The TEOM results obtained on n-hexane, n heptane, n-octane, toluene and p-xylene on a commercial FCC catalyst and on pure rare-earth exchanged zeolite Y under non-reacting conditions (373-) are analysed in detail. It is found that intracrystalline diffusion is not the limiting factor affecting the overall rates of adsorption and desorption for the systems studied. Instead, it is the transport of molecules between the adsorbed and vapour phases at the edge of zeolite crystallites that is the limiting transport step affecting the overall kinetics. For the FCC catalyst, the limiting step is the transport of molecules at the zeolite-matrix interface rather than, say, the matrix-vapour interface. Local rate constants for the desorption of the hydrocarbons at the rate-controlling interface have been obtained.     

Damping of vinyl acetate–n‐butyl acrylate copolymers

A photopolymerization process at room temperature was devised to copolymerize vinyl acetate (VAc) and n‐butyl acrylate (BA) mainly to prepare rubber‐like damping sheet bearing pressure‐sensitive adhesive property in this study. The investigations using both the differential scanning calorimeter and rheometric dynamic analysis show the existence of two glass transition temperatures for each copolymer. The scanning electron microscopic pictures reveal that the degree of microphase separation increases with increasing annealing time at 70°C. It was suggested that the rubbery domain (formed by the PBA blocks) disperses in the glassy domain (constituted by the PVAc blocks), making an effective damping entity. Excellent damping was observed for the copolymer samples, with the tanδ peak values as high as 1.76–1.80 at a certain temperature range and with tanδ> 0.3 at quite wide temperature ranges. In addition, the copolymers containing more VAc tend to have the higher damping. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1396–1403, 2004     

一种支持细粒度并行的SDN虚拟化编程框架

软件定义网络(software defined network,简称SDN)通过集中式的控制器提高了网络的可编程性,成为近年来网络领域非常热门的话题。以Openflow网络为代表的软件定义网络将逻辑控制与数据转发相隔离,为网络虚拟化技术提供了良好的平台。集中式的抽象与控制使得SDN虚拟化框架的处理效率成为主要瓶颈。现有的SDN虚拟化框架由于缺乏对细粒度并行的支持,为编程人员充分利用多核/众核资源、控制更大规模的网络带来了极大的挑战。为了提高SDN虚拟化框架的处理效率,提出一种新的SDN虚拟化编程框架,通过新颖的API和运行时,在框架内部支持细粒度的并行处理。该框架通过对网络中流和网络资源进行抽象,使开发人员可以直接通过划分流空间来定义不同的虚拟网络,利用无锁的编程方式对共享的网络资源和流进行操作。实验结果表明,该框架在逻辑控制的执行效率方面具有良好的可扩展性,可以创建出更大规模的虚拟网络,并对其进行更为复杂的控制。     

Enhanced corrosion prevention effect of polysulfone–clay nanocomposite materials prepared by solution dispersion

A series of polymer–clay nanocomposite (PCN) materials containing polysulfone (PSF) and layered MMT clay were successfully prepared by effectively dispersing inorganic nanolayers of MMT clay in an organic PSF matrix via a solution dispersion technique. The synthesized PCN materials were subsequently investigated with a series of characterization techniques, including Fourier transform infrared (FTIR) spectroscopy, wide‐angle powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The prepared PCN coatings with low clay loading (1 wt %) on cold‐rolled steel (CRS) were found to be superior in corrosion prevention to those of bulk PSF, based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and electrochemical impedance spectroscopy (EIS) in a 5 wt % aqueous NaCl electrolyte. The effects of material composition on the molecular barrier, mechanical strength and optical clarity of PSF and PCN materials, in the form of membranes, was also studied by molecular permeability analysis (GPA), dynamic mechanical analysis (DMA) and UV‐Visible transmission spectra, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 631–637, 2004     

Thermal properties measurements of renatured gelatin using conventional and temperature modulated differential scanning calorimetry

The thermal properties of amorphous gelatin films and gelatin films with renatured structural order were measured by using conventional and temperature modulated differential scanning calorimetry (DSC). Different amounts of gelatin structural order associated with a melting enthalpic change in the DSC measurement were prepared based on different gelatin drying conditions. Two consecutive heating and cooling DSC measurements on the gelatin films showed that there was no change in the glass‐transition temperature (T_g) for the amorphous gelatin but there was a decrease in the T_g for the structural gelatin on the second DSC scan. This decrease was attributed to the plasticizing effect from the release of originally hydrogen‐bonded water associated with the structural gelatin. In addition, a reversing endotherm observed upon melting of the structural gelatin during a temperature modulated DSC measurement indicated that the transition of bound water to free water occurred as the partial triple‐helix gelatin melted. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1795–1801, 2006