Abstract: A heat transfer surface monitoring (HTSM) system and cell for direct detection and monitoring of fouling, scaling, corrosion, and pitting of heat transfer surfaces. The system has a heat transfer plate (HTP) that has a heat transfer monitoring surface (HTMS). The system also includes an edge-lit light guide and light source to illuminate the HTMS, a fluid flow channel module, a heating/cooling module, a surface imaging module to view the HTMS, and a system controller. The environment is controlled to mimic the environment within heat exchange equipment, which are indicative of the changes inside heat exchange equipment. Output of signals relating to the HTMS are used as a guide mitigate problems related to the monitored heat exchange equipment. The system can also use a heat exchanger cylindrical tube with slit light guides along the tube, and the surface imaging module views the inner surface of the heat exchanger cylindrical tube.

Abstract: The invention relates to selection of bacterial strain for use in treating serotonin deficiency and/or a disease related to serotonin deficiency by culturing bacteria of a lactic acid producing bacterial strain, under aerobic conditions, in a culture medium comprising tryptophan. Any serotonin produced by the bacteria of the lactic acid producing bacterial strain in the culture medium is detected and the lactic acid producing bacterial strain is selected as effective in treating serotonin deficiency and/or a disease related to serotonin deficiency in a subject if serotonin is detected in the culture medium.

Abstract: A high electron mobility transistor is disclosed, which takes advantage of the increased mobility due to a two dimensional electron gas occurring in GaN/Al.sub.x Ga.sub.1-x N heterojunctions. These structures are deposited on basal plane sapphire using low pressure metalorganic chemical vapor deposition. The electron mobility of the heterojunction is aproximately 620 cm.sup.2 per volt second at room temperature as compared to 56 cm.sup.2 per volt second at 180.degree. K. and decreased to 19 cm.sup.2 per volt second at 77.degree. K. The mobility for the heterostructure, however, increased to a value of 1,600 cm.sup.2 per volt second at 77.degree. K. and saturated at 4.degree. K.