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.
Microfluidic technology for in vitro embryo production
In the last decade the use of in vitro production of mammalian embryos and the utilization of assisted reproductive technologies such as embryo transfer, cryopreservation, and cloning are being used to produce genetically superior livestock. However, efficiencies of these assisted reproductive technologies (ART'S) are low. For these ART's to become more commercially viable, the efficiencies must improve. Despite this importance of reproduction for the livestock industry, little progress in decreasing embryonic mortality has been made. The livestock industry has succeeded in achieving large increases in average milk production of dairy cattle, growth rate in beef cattle and leanness in swine but reproductive efficiency has actually decreased. For example, research has provided little progress toward developing an objective method to examine viability of a single living embryo. At the same time, the growth of miniaturization technologies beyond integrated circuits and towards small mechanical systems has created opportunities for fresh examination of a wide range of existing problems. While the investigation and application of miniaturization technologies to medicine and biology is progressing rapidly, there has been limited exploration of microfabricated systems in the area of embryo production. We have taken a major step in demonstrating microfluidic systems for embryo manipulation and analysis.
Tests of composite beams with web holes
Tests of composite beams comprising a concrete slab supported on a steel deck and a steel wide-flange shape containing large web openings are described. Special attention is directed to the amount of shear connection between slab and steel section in the region of a web hole, and on the effect of construction loads acting on the steel section prior to composite action being effective.It is shown that limited shear connection at the hole will significantly affect the strength when loading produces a high shear-to-moment ratio, and a theory is presented which conservatively takes this into account. The effect of construction loads on unshored construction is shown to be small when these do not exceed 60% of the non-composite beam resistance at the hole.