Obstacle avoidance for autonomous land vehicle navigation in indoor environments by quadratic classifier

A vision-based approach to obstacle avoidance for autonomous land vehicle (ALV) navigation in indoor environments is proposed. The approach is based on the use of a pattern recognition scheme, the quadratic classifier, to find collision-free paths in unknown indoor corridor environments. Obstacles treated in this study include the walls of the corridor and the objects that appear in the way of ALV navigation in the corridor. Detected obstacles as well as the two sides of the ALV body are considered as patterns. A systematic method for separating these patterns into two classes is proposed. The two pattern classes are used as the input data to design a quadratic classifier. Finally, the two-dimensional decision boundary of the classifier, which goes through the middle point between the two front vehicle wheels, is taken as a local collision-free path. This approach is implemented on a real ALV and successful navigations confirm the feasibility of the approach.

Effect of vapor phase corrosion inhibitor on microbial corrosion of aluminum alloys

Vapor phase corrosion inhibitors were used to investigate the antimicrobial activities and anticorrosion of aluminum alloy. Aspergillus flavus, A. niger, A. versicolor, Chaetomium globosum and Penicillium funiculosum had moderate to abundant growth on the aluminum alloy AA 1100 at Aw 0.901, while there was less growth at Aw 0.842. High humidity stimulated microbial growth and induced microbial corrosion. Dicyclohexylammonium carbonate had a high inhibitory effect on the growth of test fungi and the microbial corrosion of aluminum alloy, dicyclohexylammonium caprate and dicyclohexylammonium stearate were the next. Aluminum alloy coating with vapor phase corrosion inhibitor could prevent microbial growth and retard microbial corrosion.

Two-step cell disruption for the extraction of membrane-associated recombinant protein from Saccharomyces cerevisiae

The use of rDNA technology to express heterologous proteins has been very successful during the last several years. Choice of an expression host is very important in order to retain the biological activity of recombinant proteins. Baker's yeast, Saccharomyces cerevisiae, is a eucaryotic GRAS organism suitable for the expression of biologically active proteins. Specifically, hepatitis B surface antigen (HBsAg) is expressed in baker's yeast. Because the yeast cells need to be disrupted for the recovery of bioactive intracellular proteins and because the protein HBsAg is hydrophobic and has a tendency to become associated with cell membranes, the use of detergent increases the recovery yield. In order to remove most of the contaminants from yeast, a two-step disruption/extraction scheme has been developed that facilitates downstream processing. Furthermore, it also has the advantage of minimizing proteolytic actions on the recombinant protein by removing most of the contaminants and proteases into the supernatant during the first disruption step, while keeping the desired protein in the pellet fraction. Final recovery is then achieved by the extraction process. Parameters affecting the disruption/extraction processes have been discussed.