Preservation of cells and tissues by freezing at temperatures below 70°C has led to new possibilities for the storage of germ cells for fertility preservation. During the freezing process problems might occur, the greatest being ice crystallization which can cause membrane destruction and thus cell death. To minimize this risk, solutions that reduce the freezing point can be added to reduce crystallization and increase survival rates. These solutions are called cryoprotectants. The best method for freezing is still not known.The aim of this study was to analyze the effect of various parameters on the survival rate of human semen frozen with liquid nitrogen. The parameters investigated were thawing method (incubator or water bath) and container choice (straw or ampoule). In addition, two different cryoprotectants were tested.The method used was the instruction for preservation with Sperm CryoProtec™ II from Nidacon. In total 16 samples were collected for the first test and 13 samples for the second test. Sperm concentration and motility was measured.There seem to be no significant differences depending on container choice or thawing method leading to the conclusion that the most cost effective method of storage and thawing may be used. A small but significant difference was found in survival after thawing dependent on cryoprotectant p=0.041. However the study sample was limited and further studies might be of value.

Hundreds of ready-mix concrete trucks are dispatched daily from ready-mix concrete plants. On average, a concrete truck has a carrying capacity ranging from 7 to 9 cubic metres of concrete, requiring about 1500 litres of water. In addition, 500 to 1300 litres of water are used to wash out the excess concrete when the truck returns. Based on these figures, it is clear that the ready-mixed concrete industry consumes large amounts of fresh water. The purpose of this study is to determine the feasibility of using the wash water as mixing water in new concrete. The specific goal of this project is to determine the influence of the high pH and dissolved solids content of the wash water on the durability of concrete, particularly with respect to de-icing salt induced corrosion of steel reinforcement. Two types of mix designs were used in this research: a standard class N and a higher strength, structural C2 concrete. Two sets of concretes specimens were made with both mix designs: one with wash water and one with clean water. The project consists of a multi-component experimental program, beginning with wash water characterization, then pore solution and cement chemistry, followed by an evaluation of the effect of wash water on concrete workability and mechanical properties, resistance to de-icing salt scaling, and corrosion of reinforcing steel embedded in the concrete. In addition, the effect of the wash water on the effectiveness of air entraining agents (AEA) is being determined using air void analysis of specimens with different AEA contents. On the basis of the results obtained from the comparative study using wash water versus tap water, it appears that wash water can be used as mixing water for the production of concrete without compromising the durability properties related to corrosion and salt scaling performance. In addition, the mechanical and plastic properties of wash water concrete meet all standards pertaining to the use of wash water concrete and are similar to those of tap water concrete. Finally, the pore solution, thermal analyses, and water analyses of wash water and tap water showed comparable results. Overall, with regards to the tests conducted thus far, the use of wash water as mixing water in concrete poses no durability concerns.

Thesis (M.S. in environmental science)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 26, 2010). "School of Earth and Environmental Sciences." Includes bibliographical references (p. 48-51).

Thesis (M.M.A.)--University of Washington, 2009. / Title from Web page (viewed on Feb. 3, 2010). Includes bibliographical references (leaves 20-23).

Thesis (M.M.A.)--University of Washington, 2009. / Title from Web page (viewed on Feb. 3, 2010). Includes bibliographical references (leaves 41-45).

Thesis (M.M.A.)--University of Washington, 2009. / Includes bibliographical references (leaves 20-23). Also available on the World Wide Web.

Thesis (M.M.A.)--University of Washington, 2009. / Includes bibliographical references (leaves 41-45). Also available on the World Wide Web.

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Graduation date: 1984