Electrothermal branding for embryo labeling
A novel embryo labeling technique based on electrothermal branding is developed. Two types of micro branding irons are fabricated and tested. One utilizes 25 /spl mu/m tungsten wire as the heating element. The other utilizes surface micromachining techniques to fabricate polysilicon branding irons. The thermal behavior of the branding irons and the heat distributions in the embryos are analytically modeled. Micron-scale labels on unfertilized bovine embryos are achieved.
Microfabrication Techniques for Plastic Microelectromechanical Systems (MEMS)
Abstract : This report presents research and development of new micromachining techniques and fabrication technologies for the construction of plastic MEMS devices. Plastic MEMS are of major importance in the implementation of miniature chemical reaction systems, such as DNA diagnostic, bacteriophage, and other bio-assays chips. Further, because of their low temperature construction, plastic MEMS devices can be integrated with conventional electronic circuits easily and inexpensively. Three main technology directions were conducted. First, technology developments for implementing plastic microsystems using both surface and bulk micromachining techniques were investigated. Surface micromachining techniques include deposition of thin and thick polymer films using vacuum and spin-casting techniques. Bulk micromachining of plastics is used for creating a viable technology for system substrates. Bulk micromachining techniques include injection molding, embossing, casting, bonding and lamination. Secondly, the integration of surface and bulk micromachining technologies leads to a robust technology for creating complete plastic microsystems. The third development direction was in the implementation of the aforementioned developed plastic micromachining technologies as several demonstration devices including microactuators, microvalves, a micropump, a microdevice for polymerase chain reactions (PCR), a capillary electrophoresis (CE) microdevice for DNA separations, and devices for patterning protein doped conductive polymers using laminar flows.
Control of the homopause level
Abstract This paper reviews the hypothesis that internal gravity wave breaking in the factor responsible for upper atmosphere turbulence generation and control of the number density at the homopause level. Available data from Mars and Earth support the hypothesis, originally introduced by Lindzen, that breaking thermal tides are responsible for the necessary turbulence. The lowest-order, equatorially trapped, westward-propagating diurnal tidal mode is the primary cause on the Earth, and lower-order westward-propagating semidiurnal modes are the primary cause on Mars. The frequencies and vertical wavenumbers of the responsible modes determine the eddy diffusion coefficients; energy density is only indirectly involved by determining which modes can break. A general scale relationship between tidal heating and velocity amplitude can be used to assess the breaking potential of tidal modes, and is used here as the basis for arguing that the number density at the Martian homopause is likely to have been stable over much of geologic time. Difficulties with this approach arise in the cases of Venus and Titan because of their peculiar zonal winds. For Jupiter and Saturn, internal gravity waves generated by nontidal mechanisms probably control the homopause.