Simulation modeling of high-throughput cryopreservation of aquatic germplasm: a case study of blue catfish sperm processing.

Emerging commercial-level technology for aquatic sperm cryopreservation has not been modeled by computer simulation. Commercially available software (ARENA, Rockwell Automation, Inc. Milwaukee, WI) was applied to simulate high-throughput sperm cryopreservation of blue catfish (Ictalurus furcatus) based on existing processing capabilities. The goal was to develop a simulation model suitable for production planning and decision making. The objectives were to: 1) predict the maximum output for 8-hr workday; 2) analyze the bottlenecks within the process, and 3) estimate operational costs when run for daily maximum output. High-throughput cryopreservation was divided into six major steps modeled with time, resources and logic structures. The modeled production processed 18 fish and produced 1164 ± 33 (mean ± SD) 0.5-ml straws containing one billion cryopreserved sperm. Two such production lines could support all hybrid catfish production in the US and 15 such lines could support the entire channel catfish industry if it were to adopt artificial spawning techniques. Evaluations were made to improve efficiency, such as increasing scale, optimizing resources, and eliminating underutilized equipment. This model can serve as a template for other aquatic species and assist decision making in industrial application of aquatic germplasm in aquaculture, stock enhancement, conservation, and biomedical model fishes.

A quality assurance initiative for commercial-scale production in high-throughput cryopreservation of blue catfish sperm.

Cryopreservation of fish sperm has been studied for decades at a laboratory (research) scale. However, high-throughput cryopreservation of fish sperm has recently been developed to enable industrial-scale production. This study treated blue catfish (Ictalurus furcatus) sperm high-throughput cryopreservation as a manufacturing production line and initiated quality assurance plan development. The main objectives were to identify: (1) the main production quality characteristics; (2) the process features for quality assurance; (3) the internal quality characteristics and their specification designs; (4) the quality control and process capability evaluation methods, and (5) the directions for further improvements and applications. The essential product quality characteristics were identified as fertility-related characteristics. Specification design which established the tolerance levels according to demand and process constraints was performed based on these quality characteristics. Meanwhile, to ensure integrity throughout the process, internal quality characteristics (characteristics at each quality control point within process) that could affect fertility-related quality characteristics were defined with specifications. Due to the process feature of 100% inspection (quality inspection of every fish), a specific calculation method, use of cumulative sum (CUSUM) control charts, was applied to monitor each quality characteristic. An index of overall process evaluation, process capacity, was analyzed based on in-control process and the designed specifications, which further integrates the quality assurance plan. With the established quality assurance plan, the process could operate stably and quality of products would be reliable.

Fabrication method of high-quality Ge nanocrystals on patterned Si substrates by local melting point control.

The local melting point of a Ge thin film can be controlled by a hole-array pattern on the host Si substrate due to the variations in the stress distribution and the surface morphology induced by the pattern. A simple annealing process is developed from this effect to produce Ge NCs with a single-domain-crystal size over 20 nm, confirmed by transmission electron microscopy and Raman spectroscopy, from an electron-gun-evaporated Ge thin film on the patterned Si substrate. The effect of the dimensions of the hole array is also investigated. Photoluminescence observed around 1157 nm from some of the samples shows the possibility of improving the infrared emission capability by this proposed method.