A rotary slurrifier of this invention comprises a pair of spinning discs, which throw a first fluid into a larger mass of second fluid in paired and flow connected impact cavities, within a counter-rotating cavity shell. A part of a support member for supporting an optical sensor is pushed against the surface of a sheet by a spring so as to maintain the gap between the sensor and the sheet surface. The system then uses words and multi-word terms and phrases identified in the free to text to identify concepts in the free text. Additionally, for each vertex of the plurality of graphics primitives, the method comprises determining a 3D coordinate frame, wherein such determining step includes using the at least two texture coordinate gradient vectors computed for the respective graphics primitive for orienting the 3D coordinate frame. The compositions of the invention provide stable visual indication, rapid initial kill, consistent long term kill with chemical and rheological stability.