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Citric acid production by Aspergillus nigerBowes, Isabelle January 1980 (has links)
No description available.
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Quantification of fungal biomass growth during citric acid production by Aspergillus niger on expanded clay solid substrateIqbal, Qaiser. January 1900 (has links)
Thesis (M.Sc.). / Written for the Dept. of Bioresource Engineering. Title from title page of PDF (viewed 2008/07/30). Includes bibliographical references.
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Effect of dietary citric acid supplementation & use of non-linear models on growth performance in Venda chickensZulu, Blantina Fangele January 2023 (has links)
Thesis (M.Sc. (Animal Production)) -- University of Limpopo, 2023 / The development curve of Venda chicken fed with various amounts of citric acid was
evaluated using nonlinear models in an experiment. to ascertain the effects of citric
acid supplementation level on feed intake, body weight increase, and linear
measurements on Venda chickens. 200 male Venda chickens were used in the
experiment which lasted 90 days. The chicks were randomly assigned to four
treatments (0, 12.5, 25 and 50g of citric acid inclusion) with 5 replications, resulting
in 20 floor pens with 10 chicks per replicate. A completely randomized design was
employed as experimental design. Analysis of Variance (ANOVA) was used to
determine the effect of citric acid on feed intake, body weight gain, FCR, GR and
body linear measurements. Three different non-linear models, namely Gompertz,
Weibull, and Richards, were used to define the growth curves of the Venda chickens.
The Duncan multiple range test at the 5% level of significance was utilized to detect
significant differences between the means. Models were compared using coefficients
of determination (R2) and standard errors (SE). The results indicated that feed
intake, body weight, average daily gain and growth rate of Venda chickens were not
affected (p > 0.05) by citric acid supplementation levels. Similarly, Citric acid
supplementation had no effects (p > 0.05) on the shank length and wing length of
Venda chickens. However, feed conversion ratio (FCR) of Venda chickens was
improved (p < 0.05) by with an increase in citric acid supplementation. The Venda
chicken fed citric acid at grower phase and finisher phase had better growth
performances than the starter phase. Citric acid supplementation improved the back
length and thigh length of Venda chickens. The Venda chickens fed citric acid at 25g
inclusion level significantly higher back and thigh length. The coefficient of determination ranged from 0.00 to 0.98 in all the treatments. The Gompertz Model and Richards Models both exhibited the same coefficient of determination across all treatments. The model with the lowest standard error was found to best describe the growth curve of male Venda across all treatments. The Gompertz model was observed to be suitable for explaining the growth of Venda chickens fed with feed without citric acid (CA0g) and citric acid 125g inclusion (CA12.5g). The Richards model was observed to be suitable for explaining the growth of Venda chickens fed citric acid 25g inclusion (CA25g) and citric acid 50g inclusion (CA50g). It is recommended to use a supplement containing lower citric acid to enhance the body linear measurements and growth performance of the chickens. Gompertz and Richards models can be utilized to characterize the growth curve of Venda chickens. / National Research Foundation (NRF)
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Modelling the extraction of organic acids by supported liquid membranesAroca Arcaya, German E. January 1995 (has links)
No description available.
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An NMR and enzyme study of carbon metabolism in Neisseria meningitidisLeighton, Matthew Peter January 1999 (has links)
No description available.
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The mobilization of heavy metals from contaminated soil using low molecular weight organic acidsKang, Sun Ki 05 January 1994 (has links)
More than 30,000 potential Superfund sites have been identified. Heavy metals are contaminants at many of these Superfund sites. The average cost of cleanup a single-typical Superfund site currently stands at $20 million, and it is expected that the cost may escalate to $50 million within the next decade. Problems have already been encountered during the inspection of sites, and available technologies have not been effective in treating all sites. Lack of innovative strategies for dealing with contaminated soils is a major obstacle to completing Superfund site cleanup. The characteristics of low molecular weight (LMW) organic acids (citric, oxalic, and succinic acids) can be utilized as an agent in soil washing and flushing to develop an innovative technology in the remediation of the soil contaminated with heavy metals.
The objective of the work was the testing of a new remediation technology involving soil flushing and washing with LMW organic acids, designed to permanently
remove heavy metals from contaminated soil at Superfund sited. Significant amounts of heavy metals (Cu, Pb, Zn) were removed and formed soluble metal-organic complexes at higher concentrations of organic ligands. At a citric concentration of 100 mM, over 70~80% of copper, lead, and zinc were mobilized and all metals extracted were complexed with citrate ions as various forms. Therefore, the use of citric acid to remove heavy metals from contaminated soils would be less costly that using EDTA. The subsequent pH elevation by hydrated lime, Ca(OH)₂, causes the decomplexation of Pb-citrate and initiates precipitation of lead hydroxide. Results showed that slightly alkaline conditions (pH 8.5), which are much lower than that used with EDTA, are needed for substantial precipitative removal of the lead.
Increasing calcium nitrate concentration significantly improved the Pb(II) desorption via a cation exchange reaction, That is, the time required to recover lead from the contaminated soil during a soil column experiment was greatly reduced as the concentration of calcium nitrate in the influent was increased. Varying influent pH had little effort on the rate of lead mobilization in the soil columns due to the buffering capacity of the soil, which maintained the effluent pH at the soil pH. The effluent flow rate had no effect on mobilizing Pb(II) from the soil.
A higher concentration of citric acid resulted in a much faster rate of lead mobilization from the contaminated soil. Differences in lead desorption rates between influent pHs of 4.5 and 6 were significantly high. However, lead desorption curves for citrate solution at a lower pH value (pH < 4.5) were nearly identical. The flow rate of effluent has no effect at removing lead in the range of 0.1~1.0 mL/min.
Also, lead transport model was developed under the assumption of one-dimensional flow through a homogeneous porous medium. A simplified model was also developed by assuming no dispersion effect, no immobile aqueous-phase zone, and linear desorption kinetics. An analytical solution of the simplified equation was obtained by solving a partial differential equation. The computer simulations were fitted to experimental data using estimates for model parameters which were not obtainable independently in experiments. At higher concentrations and pH of the influent, this model presented here fitted well with the experimental data. / Graduation date: 2013
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The role of citric acid application on periodontally involved root surfaces in-vitro light and scanning electron microscopic study : a thesis submitted in partial fulfillment ... in periodontics ... /Chaves Filho, Eros S. January 1984 (has links)
Thesis (M.S.)--University of Michigan, 1984.
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The effectiveness of citric acid as an adjunct to surgical reattachment procedures in humans a thesis submitted in partial fulfillment ... periodontics ... /Mason, William E. January 1984 (has links)
Thesis (M.S.)--University of Michigan, 1984.
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The role of citric acid application on periodontally involved root surfaces in-vitro light and scanning electron microscopic study : a thesis submitted in partial fulfillment ... in periodontics ... /Chaves Filho, Eros S. January 1984 (has links)
Thesis (M.S.)--University of Michigan, 1984.
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The effectiveness of citric acid as an adjunct to surgical reattachment procedures in humans a thesis submitted in partial fulfillment ... periodontics ... /Mason, William E. January 1984 (has links)
Thesis (M.S.)--University of Michigan, 1984.
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