We present the use of the polysaccharide chitosan for immobilizing biomolecules on microfabricated device surfaces. The main advantages of chitosan are its abundance of primary amine groups and its ability to be elect...
详细信息
Intrinsic Optical Signal (IOS) imaging is a widely accepted technique for imaging brain activity. We propose an integrated device consisting of interleaved arrays of gallium arsenide (GaAs) based semiconductor light s...
详细信息
Porous polyethylene oxide–b–polyfluorooctylmethacrylate (PEO−b−PFOMA) diblock copolymer films were drop cast onto substrates from Freon (1,1,2-trichlorotrifluoroethane) in a humid atmosphere. The pores in the films ...
详细信息
Porous polyethylene oxide–b–polyfluorooctylmethacrylate (PEO−b−PFOMA) diblock copolymer films were drop cast onto substrates from Freon (1,1,2-trichlorotrifluoroethane) in a humid atmosphere. The pores in the films exhibit long range hexagonal order in some cases, depending on the PFOMA-to-PEO molecular weight ratio. Films with the best ordered pores were formed with PFOMA-to-PEO ratios of 70kDa:2kDa. The pores in the polymer films derive from water droplets that condense as Freon evaporates. The polymer stabilizes the water droplets, or “breath figures,” which act as an immiscible template that molds the porous film. Increased polymer hydrophobicity reduces the water wettability of the air/Freon interface, which in turn decreases water droplet nucleation, thus influencing the final pore size and spatial order in the polymer films. We describe how water droplet nucleation influences the final pore size and packing order in the polymer films.
In attempts to develop novel functional additives for thermoplastic and thermoset polymer coatings, various sizes of microcapsules containing a silicone fluid which could facilitate the release of the coating from a m...
详细信息
In attempts to develop novel functional additives for thermoplastic and thermoset polymer coatings, various sizes of microcapsules containing a silicone fluid which could facilitate the release of the coating from a metallic substrate were prepared by in-situ polymerization. Fill content, size of capsules, wall-thickness, and surface morphology were observed by TGA, TEM, SEM, EDX, optical and NMR microscopy. The capsules were dispersed in polymeric coatings and the release of their content through mechanical means was followed microscopically.
We investigate the formation of ringlike deposits in drying drops of DNA. In analogy with the colloidal “coffee rings,” DNA is transported to the perimeter by the capillary flow. At the droplet edge, however, DNA fo...
详细信息
We investigate the formation of ringlike deposits in drying drops of DNA. In analogy with the colloidal “coffee rings,” DNA is transported to the perimeter by the capillary flow. At the droplet edge, however, DNA forms a lyotropic liquid crystal (LC) with concentric chain orientations to minimize the LC elastic energy. During the final stages of drying, the contact line retracts, and the radial stress causes undulations at the rim that propagate inward through the LC and form a periodic zigzag structure. We examine the phenomenon in terms of a simple model based on LC elasticity.
Rice husk can be an interesting source of raw material for obtaining silica, due to its composition, availability and cost. The extraction process of silica from rice husk can be divided in two parts. First some compo...
详细信息
Rice husk can be an interesting source of raw material for obtaining silica, due to its composition, availability and cost. The extraction process of silica from rice husk can be divided in two parts. First some components of rice husk are removed by acid leaching, using HCl, H2SO4, or a mixture of them, followed by calcination for burning out carbon compounds. The residue obtained after calcination is composed of about 95% amorphous silica. In this work, silica was produced from rice husk following the steps previously described, using leaching solutions of 10% HCl, 10% H 2SO4 and a mixture of 10% HCl and 10% H2SO 4. Calcination of leached materials was carried out at 600 or 700°C for 3 h. The silica powder obtained presented a mean particle size of 18 μm, around 98% amorphous SiO2 with a specific surface area of about 300 m2/g.
Crystal-melt interfacial free energies (γ) are computed for hcp Mg by employing equilibrium molecular-dynamics (MD) simulations and the capillary-fluctuation method (CFM). This work makes use of a newly developed emb...
Crystal-melt interfacial free energies (γ) are computed for hcp Mg by employing equilibrium molecular-dynamics (MD) simulations and the capillary-fluctuation method (CFM). This work makes use of a newly developed embedded-atom-method (EAM) interatomic potential for Mg fit to crystal, liquid, and melting properties. We describe how the CFM, which has previously been applied to cubic systems only, can be generalized for studies of hcp metals by employing a parametrization for the orientation dependence of γ in terms of hexagonal harmonics. The method is applied in the calculation of the Turnbull coefficient (α) and crystalline anisotropies of γ. We obtain a value of α=0.48, with interfacial free energies for different high-symmetry orientations differing by approximately 1%. These results are compared to those obtained in previous MD-CFM studies for cubic EAM metals as well as experimental studies of solid-liquid interfaces in hcp alloys. In addition, the implications of our results for the prediction of dendrite growth directions in hcp metals are discussed.
We develop a time resolved fluorescence microscopy system to image the dynamics of optoinjection produced by the delivery of a highly focused pulsed Nd:YAG (λ=532nm, 6ns) laser microbeam to the cell membrane of PtK2 ...
详细信息
暂无评论