. (1994) Effect of cultural and nutritional conditions on the control of flocculation expression in Saccharomyces cerevisiae. Can. J. Microbiol. 40 , 851-857.
Effect of cultural and nutritional conditions on the control of
Scanning and transmission electron microscopic studies revealed the presence of slime-like, amorphous material on the surface of
RIVE 4-2-1 cells, independently, whether they were in flocculated or in non-flocculated state. Close contact of the adjacent cells via the merging outermost cell wall layers was found, however, only in the case of floc formation, which was induced by cultivating the cells in the presence of 6% (v/v) ethanol. Irreversible loss of the flocculation ability of the cells by treatment with proteinases suggests that proteinaceous cell surface molecules as lectins contribute to the cell-to-cell interaction during flocculation. Both proteinase K and pronase treatments removed a distinct outer layer of the cell wall, which indicated that the protein moieties of the phosphogalactomannan outer surface layer has a crucial role in the maintenance of cell wall integrity. In the case of lysing enzyme treatment the removal of the outermost layer was also observed as the first step of the cell wall digestion, while driselase treatment resulted in almost complete digestion of the cell wall.
Iodine-125 from aqueous solutions were sorbed by several naturally occurring minerals such as kaolinite, ferrous oxide and hydrous aluminium oxides. Coagulation-flocculation and column experiments were conducted and compared to determine which method could more effectively and conveniently treat the effluent. At a pH value of 4.5, the mentioned minerals exhibited modest positive charges being able to attract the anions of125I. For activities of effluents normally produced by different users, both treatments by coagulation-flocculation and column (mixture of kaolin and soil material) experiments were suitable. However, column methods were more effective, easy to handle, have low capital and maintenance costs for treating the wastes.
Authors:C. Greis, A. Düker, B. Allard, P. Roos, and E. Holm
Fresh water from Lake Svartsjön, Sweden, was collected and four fractions were prepared: (1) adsorption on DEAE, (2) flocculation
with Ca2+, (3) co-precipitation with Fe hydrous oxide and (4) co-precipitation with Mn hydrous oxide. The plutonium level in the lake
is 65 fg/l (222 μBq/l), measured by ICP-QMS and ICP-SFMS. Pronounced accumulation in fractions (1) (34%) and (2) (66%), combined
with observed levels of organic matter indicate that plutonium is predominantly associated with organic matter. Measurements
of isotopic ratios indicate that 77% of the plutonium originates from weapons testing and the remaining appears to originate
from the Chernobyl accident.
Authors:H. Ortiz-Oliveros, R. Flores-Espinosa, H. Jiménez-Domínguez, M. Jiménez-Moleón, and D. Cruz-González
Preliminary testing of dissolved air flotation (DAF) for wastewater treatment is presented. A combined coagulation-flocculation/DAF
column system is used to remove oil and 60Co from nuclear industry wastewater. In this work, operational conditions and coagulant/flocculant concentrations are optimized
by varying pH. Determinations of air-solids ratio (G/S), retention time (θ), pressure (P), volume of depressurized air–water mixture (V), turbidity and 60Co concentrations are reported. The effect of the treatment on the efficiency of separation of oily residues is also discussed.
The results establish that the coagulant/flocculant system, formed by a modified polyamine (25 mgL−1) and a slightly cationic polyacrylamide (1.5 mgL−1), under specific operational conditions (pH = 7, mixing intensity Im1 = 300 s−1 and Im2 = 30 s−1), allowed the destabilization of colloidal matter, resulting in resistant flocs. It was concluded that by using G/S = 0.3, θ = 15 min, P = 620 kPa and V = 0.0012 m3, the greatest percentage removals of oil, turbidity, total cobalt and 60Co were obtained. These preliminary results then show that dissolved air flotation represents a good alternative for treatment
of nuclear industry wastewater contaminated with radionuclides.
Authors:B. Neelakantam, N. V. Sridevi, A. M. Shukra, P. Sugumar, S. Samuel, and Dr. Lingala Rajendra PhD
Phage display technology is a powerful in vitro method for the identification of specific monoclonal antibodies (antibody fragments) to an antigenic target and allows the rapid generation and selection of high affinity, fully human antibodies directed toward any disease target appropriate for antibody therapy. In the present study, we exploited the phage display technology for the selection of an antigen binding fragment (Fabs) toward tetanus toxoid using human naïve phage antibody library constructed from peripheral blood lymphocytes of naïve human donors. The phages displaying Fab were subjected to three rounds of bio-panning with tetanus toxoid as antigen on a solid phase. The high affinity antibody fragments were expressed in HB2151 strain of Escherichia coli and purified by immobilized metal affinity chromatography. The binding activity and specificity of the antibody fragment was established by its reactivity toward tetanus toxoid and non-reactivity toward other related toxins as determined by enzyme-linked immunosorbent assay and immunoblot analysis. The selected Fab fragment forming the antigen-binding complexes with the toxoid in flocculation assay indicates that the Fab may have a potential neutralizing ability toward antigen.
The complexation of the uranyl ion with humic acid is investigated. The humic acid ligand concentration is described as the
concentration of reactive humic acid molecules based on the number of humic acid molecules, taking protonation of functional
groups into account. Excess amounts of U(VI) are used and the concentration of the humic acid complex is determined by the
solubility enhancement over the solid phase. pH is varied between 7.5 to 7.9 in 0.1M NaClO4 under normal atmosphere and room temperature. The solubility of U(VI) in absence of humic acid is determined over amorphous
solid phase between pH 4.45 and 8.62. With humic acid, only a limited range of data can be used for the determination of the
complexation constant because of flocculation or sorption of the humic acid upon progressive complexation. Analysis of the
complex formation dependency with pH shows that the dominant uranyl species in the concerned pH range are UO2(OH)+ and (UO2)3(OH)5+. The complexation constant is evaluated for the humate interaction with the to UO2(OH)+ ion. The stability constant is found to be logβ = 6.94±0.3 l/mol. The humate complexation constant of the uranyl mono-hydroxo species thus is significantly higher than that
of the nonhydrolyzed uranyl ion (6.2 l/mol). Published data on the Cm3+, CmOH2+ and Cm(OH)2+ humate complexation are reevaluated by the present approach. The higher stability of the hydrolysis complex is also found
for Cm(III) humate complexation.
Authors:V. B. Lazarev, G. P. Panasyuk, G. P. Boudova, and I. L. Voroshilov
To determine the role of the forms of fixed water in the relaxation of the silica structure, silica as treated with hot water vapour in an autoclave, and the kinetics of its dehydration were studied by thermogravimetry. Five successive stages of relaxation were established:1.Flocculation of globules, accompanied by evaporation of the polymolecular water layer situated in the interglobular space.2.Formation of a glassy structure, accompanied by further water evaporation.3.Transition of the glassy structure to cristobalite with the formation of large particles.4.Formation of quartz seeds within each particle.5.Aggregation of oriented seeds into monocrystals of quartz.