A novel, electrically protein-manipulated microcantilever biosensor for enhancement of capture antibody immobilization

This study demonstrated a microcantilever biosensor for enhancement of capture antibody immobilization. The electrically protein-manipulated, microcantilever biosensor is featured with enhanced capture antibody immobilization, miniaturization, and high sensitivity. Thanks to the electric property of biological substances in a real environment, given charged proteins can be manipulated with attraction in solution under an electric field. It is evident that higher amount of capture antibody molecules immobilized onto sensing surfaces captures or detects specific molecules, indicating greater deflection and stresses as well. This however leads to significant cost in biosensors. With the merit of MEMS technique that allows highly fabrication-compatible integration into microcantilever biosensors, sparsely distributed antibody molecules in solution are attracted in focus onto a sensing solid surface under electric fields. As the sensing element of the gold-coated, V-shaped silicon nitride microcantilever also serves as an electrode, the electric fields are applied in a channel of flowing microfluidics by locally in-plane electrodes or by a top electrode arranged for three-dimensional fields. As expected, most charged proteins distributed in solution are effectively attracted onto the sensing area within the electric fields. This improves the efficiency of capture antibody immobilization and achieves an eight-fold reduction over the necessary amount of capture antibodies without applying electric fields. With such a successful manipulation of charged proteins, the novel microcantilever biosensor exhibits efficient use of capture antibodies in solution.     

Phase-shifting algorithms for electronic speckle pattern interferometry

A set of innovative phase-shifting algorithms developed to facilitate metrology based on electronic speckle pattern interferometry (ESPI) are presented. The theory of a phase-shifting algorithm, called a (5,1) algorithm, that takes five phase-shifted intensity maps before a specimen is deformed and one intensity map after a specimen is deformed is presented first. Because a high-speed camera can be used to record the dynamic image of the specimen, this newly developed algorithm has the potential to retain the phase-shifting capability for ESPI in dynamic measurements. Also shown is an algorithm called a (1,5) algorithm that takes five phase-shifted intensity maps after the specimen is deformed. In addition, a direct-correlation algorithm was integrated with these newly developed (5,1) or (1,5) algorithms to form DC-(5,1) and DC-(1,5) algorithms, which are shown to improve significantly the quality of the phase maps. The theoretical and experimental aspects of these two newly developed techniques, which can extend ESPI to areas such as high-speed dynamic measurements, are examined in detail.     

Line inclusions at anisotropic bimaterial interface

A line inclusion at the interface of an anisotropic bimaterial is studied. The line inclusion is assumed to be inextensible but with negligible bending rigidity. Complete singular fields near tips of the line inclusion are derived. The near-tip stress field exhibits singularities of the types in general with r being the distance measured from the tips. The near-tip fields are similar to those for fully closed interface cracks. In analogy to the stress intensity factors defined for interface cracks, strain intensity factors are introduced to characterize the near-tip fields. It is shown that there are only two independent strain intensity factors and corresponding modes of deformation. Complete displacement and stress fields and the corresponding strain intensity factors as the line inclusion is under uniform remote loading are given. Strain intensity factors for a line inclusion very near some anisotropic bimaterial interface are also derived.     

Flame retardancy of water-based intumescent coatings with etherified melamine–formaldehyde and polyvinyl acetate copolymer hybrid resin

This study investigated etherified melamine–formaldehyde (MF) and polyvinyl acetate copolymer hybrid resins with different intumescent formulations to improve the flame retardancy of plywood. The CO and CO₂ emissions of intumescent coatings were also investigated. The miscibility of two resins is indicated by a single cure peak. Intumescence with a hybrid resin demonstrated better flame retardancy relative to that with a pure etherified MF resin. The results of scanning electron microscopy and a cone calorimeter test indicated that a lower binder resin (BR) content enhances fire retardancy and forms an ideal char. Furthermore, an evaluation of total heat release in addition to CO and CO₂ emissions (for 300 s) revealed that the intumescent coating had the same flame retardancy when the BR content was increased by 40%. The survival duration of the chemical structures of the phosphocarbonaceous chars was verified using Fourier-transform infrared spectroscopy and solid-state phosphorus-31 nuclear magnetic resonance analyses.     

Anti-plane shear crack in a sandwich composite

An analysis of an anti-plane shear crack in a sandwich composite is presented. The sandwich composite is formed by bonding one layer and two half spaces, each being anisotropic and dissimilar. The crack is assumed to be located in the middle layer and is inclined by an angle. The analysis is done by a complex-variable integral equation formulation based on the fundamental solution of a dislocation in the layer. The numerical results for vanishingly thin layers are shown to be consistent with those obtained by the J-integral.     

On the crack-tip fields of a dynamically propagating crack in an anisotropic elastic solid

General expressions of the crack-tip fields for a dynamically extending crack through an anisotropic elastic material are given. Based on the crack-tip fields, the associated dynamic energy release rate is also derived. Explicit results are given for transversely isotropic materials.

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Résumé On fournit des expressions générales des champs régnant à l'extrémité d'une fissure en expansion dynamique dans un matériau élastique anisotrope. En se basant sur ces champs, on déduit également la vitesse de relaxation de l'énergie dynamique qui y est associée. Des résultats explicites sont fournis pour des matériaux à isotropie transversale.

     

Transient dislocation emission from a crack tip in an anisotropic elastic material

The emission of a dislocation with a general Burgers vector from the tip of a stationary semi-infinite crack in an anisotropic elastic material is examined. The dislocation is assumed to leave the crack tip along the crack extension plane at constant speed. Explicit expressions for the transient shielding stress intensity factors at the crack tip and the drag forces on the dislocations are derived. Numerical results for a class of cubic materials and two hexagonal crystals, zinc and cobalt, are given. Dislocation emission under plane stress wave loading is discussed.