• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 34
  • 5
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 45
  • 45
  • 8
  • 6
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Optimization of culture conditions and extraction method for phycocyanin production from a hypersaline cyanobacterium

Mogany, Trisha 08 August 2014 (has links)
Submitted in fulfilment of the requirements of the degree of Master of Technology: Biotechnology, Durban University of Technology, 2014. / Cyanobacteria contain phycocyanin a light harvesting pigment found to have numerous biotechnological applications, such as: a natural colorant in food and cosmetics, fluorescent tags employed in clinical and immunological research and also in therapeutic processes. Successful phycocyanin production depends on growth characteristics, ability to accumulate high quantities of the pigment, and an effective downstream process. Therefore, the aim of this research was to optimize the extraction method and production by determining the optimal cultivation conditions for phycocyanin producing cyanobacterium. This cyanobacterium was isolated from a hypersaline water body in Kwa-Zulu Natal, and subsequently purified using traditional streak and spread plate techniques. Different cell disruption techniques and a range of buffers were evaluated for the extraction of phycocyanin. The buffer concentrations and pH was subsequently optimized. Results showed that maximum phycocyanin was extracted when cells were suspended in 50mM sodium phosphate buffer (pH-7.5) supplemented with 10 % lysozyme and then disrupted using the freeze–thaw method at -20 & 4°C. The UV-Vis absorption spectral scan of the crude extracted pigments showed a peak at 620 nm. This corresponds to phycocyanin production. Unwanted proteins were removed using a 25and 50% saturated ammonium sulphate precipitation, followed by dialysis. SDS-PAGE showed two subunits with molecular masses of 19 and 20 kDa. These masses corresponded to phycocyanin α and β subunits. Furthermore, a food grade purity ratio (A615/A280) of 1.20 was achieved. The effects of various abiotic factors (temperature, light and pH) on growth and phycocyanin production of the Cyanothece sp. was investigated. Temperature ranging from 20-45°C and pH (5-10) was evaluated for 2 weeks. Cultures were then subjected to four photoperiods (24:0, 18:06 12:12 and 8:16 h light: dark) three light intensities (25, 75 and 125 µmol photons per m2 per –s) at varying wavelengths i.e. blue, red and green and Grolux light. Ideal conditions were observed at 35°C, 125 µmol photons.m2.s-1 of Grolux light for a 16:8 light and dark photoperiod. It was observed that the highest biomass and phycocyanin production was found to be at 35°C, temperatures below or above resulted in a decrease in both growth and pigment synthesis. Phycocyanin concentration changed in response to light quality and intensity. A significantly higher (p<0.05) phycocyanin yield was found when the culture was exposed to 125 µmol photons.m2.s-1 of Grolux light compared with the other three light conditions. Using Design of experiments, a series of fractional factorial experiments were carried out to optimize media components for pigment production. The final optimized growth medium was determined from a central composite design using response surface plots together with a mathematical point-prediction tool and consisted of 2g/L NaNO3, 0.06g/L K2HPO4, 0.12 g/L MgSO4.7H2O, 0.033 g/L CaCl2.2H2O, 100g/L NaCl, 12mL minor nutrients and 0.5 trace metal. A 72 % increase in phycocyanin was observed. This research revealed that this particular Cyanothece sp. shows great potential as a reliable source of phycocyanin.
22

Effect of saline waters on soil properties and plant nutrition in Kuwait

Abu-Fakhr, Mahmud Suleiman Sayyid Ahmad,1919- January 1961 (has links)
A field and pot culture study was undertaken in an attempt to determine the effect of saline solabeya water on soil salination, gatch formation and plant uptake of nutrients. Three gatch and three sandy soil profile samples were used in this studyo The soil samples were virgin profile 'A' samples from the Experim.ental Farm Extension, cultivated profile 'B' samples from. the Experim.ental Farm and cultivated profile '0' samples from Bid'a Nursery of the Education Department. The gatch samples were collected from sites 'A', '0' and plot No.6, of the Experimental Farm. Extension, Bidta Nursery and Experimental Farm respectively. Three indicator plants Lettuce (Lactuca sativa, variety Great Lakes), green beans (Phaseolus vulgariS, variety Black Valentine), and Petunia (Petunia hybrida) were used. The effect of soil texture, change in the reaction of the medium, concentration of solabeya saline water and soil solution on gatch formation were studied. A coarse sandy subsoil horizon high in silica constituted the proper medium for gatch formation. The major cementing agents were silica and the carbonates and hydroxides of calcium and magnesium. Alumina, iron oxide and gypsum. playa minor role in cementation due to their low concentration. An increase in the alkaline reaction and concentration of the saline solution favored precipitation of potential cementing agents present as soluble constituents of the medium. The presence of gatch and use of solabeya saline water lead to the formation of saline perched water table and soil salination. Different irrigation waters, representing various dilutions of solabeya saline water were used for irrigation of pot cultures. Different increments of nutrient solutions, supplying nitrogen, phosphorus, P9tassium, calcium, magnesium, and sodium were applied to the respective treatments of the pot cultures. The development, sequence of appearance, and severity of visual symptoms of general salinity effect showed direct corrolation with salt sensitivity of the indicator plant and the degree of salinity of the medium. In all cases, the symptoms were earlier and more severe in bean, followed by lettuce and petunia. As a result of cationic and anionic antagonism and an increase in the salinity of the medium, plant uptake of N, P, Ca, K, Fe and Mn was reduced, as revealed by the level of these elements in the leaves of the indicator plants, whereas the levels of Mg, Na, B, Cl, and SO₄ increased in the leaves of the indicator plants. The application of different increments of N, P, Ca, and K to the respective treatments of the indicator plant cultures resulted in a relative increase in the level of these elements in the leaves and a specific decrease in the level of the antagonistic elements. But, due to the effect of the increase in salinity of the medium of the respective treatments, and decrease in yield of green weight, the level of these elements maintained a gradual specific decrease in. the leaves.
23

Trading quality for quantity : an assessment of salinity contamination generated by groundwater conservation policy in the Tucson Basin

Tinney, James Craig,1950- January 1987 (has links)
The State of Arizona adopted strict groundwater conservation policies under the Arizona Groundwater Act of 1980. The Act mandates direct controls on groundwater use and provides incentives to seek alternative water supplies to offset the groundwater overdraft and restrict the expansion of municipal well fields. The City of Tucson, to reduce its groundwater dependency, is contracting for Central Arizona Project (CAP) water. CAP water comes from the Colorado River and carries with it nearly a ton of salts per acre-foot. Conservation programs being investigated by the city include reclaimed wastewater reuse for municipal use and artificial recharge. Salinity, a conservative contaminant, will rise as the water carrying it evaporates away during use. Some saline incidental recharge from wastewater irrigated acreage in the municipal well field is picked-up by groundwater pumpage in what is described as the municipal water-salinity cycle. The rate of salinity pick-up is compounded in the cycle. Those responsible for achieving groundwater conservation under the mandates of the Act do not include the costs generated by salinity damages and suffered by municipal water-consumers into their conservation plans. Salinity damages costs are generated by the direct use of CAP water and the use of degraded groundwater supplies. The study results show that under assumptions of limited groundwater dilution volumes the annual rate of salinity pick-up can range from about 1.4 percent to nearly 2.0 percent. An annual average pick-up rate of 2.0 percent could degrade Tucson's groundwater supplies from the present average salinity of 300 mg/1 to 1000 mg/1 in 61 years. Thirteen scenarios were evaluated and the present value of incremental costs of both salinity damage and expenditures associated with conservation were calculated. While estimates of salinity damage costs are many times lower than the conservation program expenditures, increased salinity in groundwater will lower the future capital value of the resource in the future if ignored.
24

'n Ondersoek na die osmotiese verhoudings van sommige varswatervisse

29 October 2015 (has links)
M.Sc. (Zoology) / This study was undertaken to determine the osmotic regulation of Labeo capensis and to investigate the effectiveness of the addition of salt to water in which the fish are transported. The blood of L. capensis in tap water has a lower pH value than that of the same species acclimatized to salt water. It seems that the pH of fish transported in salt water is not altered immediately as in the case of fish transported in fresh water. In both groups the lowest pH values were reached two days after the fish had been transported ...
25

Evaluation of three fish species for culture using low salinity groundwater in the Black Belt region of Alabama

Brown, Benjamin J. Daniels, William H. January 2007 (has links) (PDF)
Thesis(M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.
26

Economic feasibilty of utilizing saline groundwater of West Alabama to produce Florida pompano in a recirculating aquaculture system

Gorman, Jacob. Adrian, John, January 2009 (has links)
Thesis--Auburn University, 2009. / Abstract. Includes bibliographical references (p. 40-43).
27

The role of ionic concentration and composition in determining diatom distributions in saline lakes /

Saros, Jasmine Elaine Gokcen, January 1999 (has links)
Thesis (Ph. D.)--Lehigh University, 1999. / Includes vita. Bibliography: leaves 94-102.
28

Pore-water chlorinities of subsurface shales

Hedberg, William Hollis, January 1967 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
29

Air -- water partitioning of volatile organic compounds and greehouse gases in the presence of salts

Falabella, James Benjamin. January 2007 (has links)
Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2008. / Teja, Amyn S., Committee Chair ; Frederick, James, Committee Member ; Wine, Paul H., Committee Member ; Eckert, Charles A., Committee Member ; Nenes, Athanasios, Committee Member.
30

A review of the use of salt water for flushing in Hong Kong: project report

Ip, Chi-kuen., 葉志權. January 1993 (has links)
published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Page generated in 0.3521 seconds