谈土工合成材料的推广应用

土工合成材料具有反滤、排水、防渗、护岸防冲、土体加固和隔离作用。文章介绍了土工合成材料的现状和前景及土工合成材料的类别、应用范围、最后阐述了它在推广应用中遇到的问题，并提出了建议。     

Photo‐reduction and adsorption in aqueous Cr(VI) solution by titanium dioxide,carbon nanotubes and their composite

BACKGROUND: This study compared the removal of aqueous Cr(VI) by multi‐walled carbon nanotubes (CNTs) modified by sulfuric acid, titanium dioxide (TiO₂) and composite of CNTs and TiO₂. RESULTS: More than 360 h contact time was needed to completely adsorb 3 mg L^?1 of Cr(VI) by CNTs, indicating that the rate of adsorption by CNTs alone was slow. The reaction time approaching equilibrium depended on the Cr(VI) concentration. XPS analysis of CNTs after adsorbing Cr(VI) showed that the Cr(VI) on the surface of CNTs was partially reduced to Cr(III). A 3 mg L^?1 solution of Cr(VI) was fully photocatalyzed by commercial TiO₂ (Degussa P25) in less than 0.5 h under UV irradiation. Unlike P25, reduction by another commercial TiO₂ (Hombikat UV100) took 4 h and more than 2 h were necessary for reduction by the composite. Thus the efficiency of Cr(VI) photo‐reduction by the composite was lower than by TiO₂, but higher than that by CNTs. XPS analysis of TiO₂ and composite showed the existence of both Cr(VI) and Cr(III) on their surfaces. CONCLUSION: In contrast to TiO₂, the reduction rate of aqueous Cr(VI) using CNTs as adsorbent was slow. P25 had a markedly higher photocatalytic efficiency than the composite or UV100 alone. Using P25 to reduce aqueous Cr(VI) has a higher potential for practical application. The diameters of TiO₂ and CNTs and the ratio of TiO₂/CNTs are key problems in the preparation of TiO₂/CNTs composite. Copyright © 2011 Society of Chemical Industry     

Polyelectrolyte multilayer electrostatic gating of graphene field-effect transistors

We apply polyelectrolyte multilayer films by consecutive alternate adsorption of positively charged polyallylamine hydrochloride and negatively charged sodium polystyrene sulfonate to the surface of graphene field effect transistors. Oscillations in the Dirac voltage shift with alternating positive and negative layers clearly demonstrate the electrostatic gating effect in this simple model system. A simple electrostatic model accounts well for the sign and magnitude of the Dirac voltage shift. Using this system, we are able to create p-type or n-type graphene at will. This model serves as the basis for understanding the mechanism of charged polymer sensing using graphene devices, a potentially technologically important application of graphene in areas such as DNA sequencing, biomarker assays for cancer detection, and other protein sensing applications.     

The Shanghai Corporate Pavilion design for World Expo in Shanghai 2010

New technologies are becoming today’s basic building blocks. This paper presents a case study of the Shanghai Corporate Pavilion for the 2010World Expo in Shanghai. From the shape of the building to the use of solar energy, the Shanghai Corporate Pavilion incorporates the state-of-art technologies to convey the spirit of the architecture. It addresses the pressing issue of energy, environment, and sustainability and reflects the spirit of Shanghai as a historically progressive yet still fast moving international metropolis.     

Electroless deposition of biocompatible Ag/W on quartz for the purpose of variotherm micro molding

Variotherm micro/nano molding demands lower heat capacity but higher thermal conductivity on being electrically heated part. Quartz mold can provide nano/micro features with high accuracy but failed to be used in real molding process due to its low thermal conductivity, which may be elevated by coating metals on it. In this paper, a novel electroless plating solution with ammonia and malic acid as double complexing agents was developed to deposit Ag/W alloys on quartz surface. A suitable surface roughness of quartz glass for Ag/W deposition was obtained at volumetric ratio (HF:H₂SiF₆:H₂O) of 1.4:1:2. The effects of malic acid concentration on the compactness, adhesion, composition, resistivity and deposition rate of the Ag/W coating were investigated. A kinetic model was established for adjusting and predicting Ag/W deposition rate in the coating fabrication process.     

Highly conducting electrospun polyaniline-polyethylene oxide nanofibrous membranes filled with single-walled carbon nanotubes

Highly conducting nanofibrous composite of well-oriented single-walled carbon nanotubes (SWNTs) in polyaniline (PANI) and polyethylene oxide (PEO) have been fabricated using electrospinning. The room temperature electrical conductivity show nearly four order enhancement with highest (11.9 wt%) loading of SWNT in the PANI–PEO blend. The temperature dependent conductivities are measured in the range of 30–300 K and the results are analyzed by the fluctuation assisted tunneling model.     

Ripening temperature affects the content and distribution of isoflavones in sufu,a fermented soybean curd

Sufu, a fermented soybean curd, was prepared by ripening the salted tofu cubes in the Aspergillus oryzae‐fermented rice–soybean koji mash at 25, 35 or 45 °C for a period of 16 days. It showed that the 16‐day ripened sufu contains less total isoflavone content (629.29–739.68 μg g^?1 dried matter) than the salted tofu before ripening (942.59 μg g^?1 dried matter). Regardless of ripening temperature, ripening causes a major reduction in the content of β‐glucoside and malonylglucoside isoflavones along with a significant increase of aglycone isoflavone content. These changes were enhanced as the ripening period extended. Among the various treatments examined, sufu ripened at 45 °C showed the greatest increase in aglycone content coupled with the greatest decrease in malonylglucosides. The distribution of malonylglucosides decreased from an initial 40.32% in the tofu cube to 9.78% after 16 days of ripening at 45 °C. Meanwhile, the distribution of aglycone increased from 13.17% to 39.88%.     

Formation and characterization of diamond crystals synthesized by microwave plasma CVD system

Abstract

Diamond crystals have been successfully synthesized on (100) Si wafer using microwave plasma CVD. The growth was conditioned in a flowing system in which the parameters, such as CH₄/H₂ ratio, pressure, temperature and microwave power were varied. Cubo‐octahedra or tetrakaidecahedra are the equilibrium shape of diamond single crystals obtained under all conditions and are therefore the basic unit for the formation of polycrystalline diamond films, mostly through repetitive twinning and secondary growth of diamond crystals on {100} habit planes of cubo‐octahedra. Both X‐ray diffraction and Raman spectroscopy were used to facilitate the analysis of the diamond crystallinity and purity. These qualities are similar to those of natural diamonds.     

Ink-jet printing and camera flash sintering of silver tracks on different substrates

A camera flash-lamp, which makes use of the enhanced photothermal effect in silver nanoparticles, was used for sintering of ink-jet printed silver tracks on Polyimide (PI), Polyethylene Terephthalate (PET) and photographic paper at room temperature. After the camera flashing the nonconductive tracks was changed and became conductive. The resistivity of all tracks on different substrates was decreased after the first flashing and the second flashing, while it exhibited a slight increase after the third and forth flashing. Irrespective of the number of flashings, the silver track printed on the PET substrate had the lowest resistivity and it can reach 6.2 μΩ cm after the second flashing, while the track that was printed on the photographic paper had the highest measured resistivity due to defects in the substrate. The thermal conductivity of the substrate had an important effect on the microstructure of the silver tracks after the flashing. The nanoparticles within the tracks printed on the photographic paper exhibited significant melting after flashing sintering. This melting was due to very low thermal conductivity of the photographic paper and slow heat dissipation to the substrate and the surroundings. The nanoparticles on the PI substrate exhibited less appreciable melting due to greater thermal conductivity of the PI and fast heat dissipation to the substrate and the surroundings.     

Wetting behaviors of hyperbranched polymer composites within ordered porous template under vibration

The wetting characteristics of hyperbranched polyesters (HBP) added cyclic olefin copolymer (COC) melt in microchannels of anodized alumina oxide (AAO) template were studied. The wetting displacements in microchannels were measured by scanning electronic microscopy (SEM). Compared with pure COC matrix, the composite flowed much longer in the microchannels under normal molding conditions. This may be attributed to the spherical shape of the HBP molecules. The flow study was extended by applying a series of high frequency vibration on the AAO template. Results show that vibration can enhance the wetting of the composite melts if phase separation does not occur. This paper provides useful information for micromolding based microfabrication, especially additives and vibration assisted micromolding. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers