Thesis (Ph. D.)--University of Michigan, 1919. / Bibliography: p. 39-40.

Thesis (Ph. D.)--Johns Hopkins University, 1915. / Biography.

Thesis (Ph. D.)--Johns Hopkins University. / Biography.

Abstract of Thesis (Ph. D.)--Ohio state University, 1923. / Autobiography.

Thesis (PH. D.)--Johns Hopkins University. / Biographical note. Description based on print version record.

Thesis (Ph. D.)--Johns Hopkins University. / Biography.

Thesis (Ph. D.)--Johns Hopkins University. / Biography.

The problems of, osmoregulation and oxygen consumption were Investigated In two species of Corixidae (Hemiptera), Cenocorixa bifida and C. expleta. Field collections support a distribution correlated with salinity. C. bifida and C. expleta acclimated to a range of different lake waters for three days showed a gain and loss of about five per cent body water in hypo and hyper-osmotic media when compared with their natural environment. Determinations of freezing point depression of blood showed that both species are able to maintain the osmotic pressure of their body fluids higher than that of the surrounding medium except in highly saline Gr₂ lake water. Both species became approximately iso-osmotic In Long lake water (concentration 435 mOs/1). The results of this study Indicate that C. bifida and C. expleta can tolerate lake waters having as low as 5 and as high as 435 mOs/1 concentration under laboratory conditions and show no visible adverse effects. On transfer to media of lower concentration than the normal environment, C. expleta became swollen and sluggish. It appears that this species is unable to tolerate very low salinities. The results also Indicate that in Gr₂ water (concentration 753 mOs/1) the blood of both species becomes hypo-osmotic probably due to the breakdown of the hyperosmoregulatory mechanism, thus resulting in death. The presence of filtered solution of amaranth and phenol red In different lake waters showed that these species drink water In hypo and hyper-osmotic media to obtain salts and water lost, in excretory products. Sections of midgut showed swelling and vacuolation of epithelial cells in G. expleta when transferred to very low salinities like Spring House water. In highly concentrated Gr₂ lake water the midgut cells In both species were shrunken and detached from the basement membrane and in time they appeared to be completely broken down. To maintain a difference of osmotic pressure between the body fluids and the surrounding medium both species do metabolic work. The measurement of respiratory rate by Warburg method and the periods of locomotory activity in nitrogen saturated media showed that both species consume more oxygen on transfer to lower and higher salinities than in their normal medium. These results suggest that both species are under osmotic stress and are doing increased metabolic work with the increasing osmotic gradient, but because of the difficulty in distinguishing this from activity, the latter may also be causing some increase in the respiratory rate. The rate of oxygen consumption in the females of both species was found to be significantly higher than the male in all salinities. It is possible that this difference could be due to a greater expenditure of energy on egg maturation. / Science, Faculty of / Zoology, Department of / Graduate

There are two basic needs globally and that is the control and supply of reliable electricity and clean water. However, one of the biggest challenges the world is facing today is the lack of fresh water resources. Lower rainfall, together with population and industry growth, are only a few factors contributing to the fast increasing strain on existing water supplies around the world. This fast increasing need therefore necessitates the investigation into finding alternative sources. One such option is that of desalination. In the last 50 years desalination technologies have been applied to produce high quality fresh water from brackish and seawater resources. In the 1980's a breakthrough was made with the introduction of the membrane desalination technology, known as the reverse osmosis (RO) process. Today newly developed technologies are improving the competitiveness of the reverse osmosis process against the traditional distillation processes. There are a number of options to increase the efficiency of a reverse osmosis plant and one option is to use warm industrial waste water as the feed water to the desalination plant. It is known that the viscosity of water is inversely proportional to its temperature. Therefore, if the feed water temperature of a reverse osmosis plant is increased the membranes will become more permeable. This will result in a higher production volume or in a lower energy demand. South Africa is on the edge of building the first fourth generation nuclear power plant, called the Pebble Bed Modular Reactor (PBMR) at Koeberg. The PBMR will produce a cooling water outlet temperature of 40°C which can be used as feed water to a reverse osmosis plant. In this study design guidelines of a reverse osmosis plant are given in nine steps. These steps were then used during a basic component design of a reverse osmosis plant coupled to the waste water stream of a PBMR nuclear power plant. Furthermore design software programs were used to simulate the coupling scheme in order to validate the outcome of the design guidelines. The results of the two design approaches compared well to one another. It furthermore showed that by using the waste water from the PBMR nuclear power plant the efficiency of the RO plant is increased and the operating cost is decreased. Fresh water can be produced at a cost of R 5.64/m3 with a specific electricity consumption of 2.53 kWh/m3. / Thesis (M.Ing. (Nuclear Engineering)--North-West University, Potchefstroom Campus, 2009.

There are two basic needs globally and that is the control and supply of reliable electricity and clean water. However, one of the biggest challenges the world is facing today is the lack of fresh water resources. Lower rainfall, together with population and industry growth, are only a few factors contributing to the fast increasing strain on existing water supplies around the world. This fast increasing need therefore necessitates the investigation into finding alternative sources. One such option is that of desalination. In the last 50 years desalination technologies have been applied to produce high quality fresh water from brackish and seawater resources. In the 1980's a breakthrough was made with the introduction of the membrane desalination technology, known as the reverse osmosis (RO) process. Today newly developed technologies are improving the competitiveness of the reverse osmosis process against the traditional distillation processes. There are a number of options to increase the efficiency of a reverse osmosis plant and one option is to use warm industrial waste water as the feed water to the desalination plant. It is known that the viscosity of water is inversely proportional to its temperature. Therefore, if the feed water temperature of a reverse osmosis plant is increased the membranes will become more permeable. This will result in a higher production volume or in a lower energy demand. South Africa is on the edge of building the first fourth generation nuclear power plant, called the Pebble Bed Modular Reactor (PBMR) at Koeberg. The PBMR will produce a cooling water outlet temperature of 40°C which can be used as feed water to a reverse osmosis plant. In this study design guidelines of a reverse osmosis plant are given in nine steps. These steps were then used during a basic component design of a reverse osmosis plant coupled to the waste water stream of a PBMR nuclear power plant. Furthermore design software programs were used to simulate the coupling scheme in order to validate the outcome of the design guidelines. The results of the two design approaches compared well to one another. It furthermore showed that by using the waste water from the PBMR nuclear power plant the efficiency of the RO plant is increased and the operating cost is decreased. Fresh water can be produced at a cost of R 5.64/m3 with a specific electricity consumption of 2.53 kWh/m3. / Thesis (M.Ing. (Nuclear Engineering)--North-West University, Potchefstroom Campus, 2009.