Thesis--Wisconsin. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains viii, 80 p.; also includes graphics. Includes bibliographical references (p. 80). Available online via OhioLINK's ETD Center

Submitted in complete fulfilment for the Degree of Master in Food Science and Technology, Durban University of Technology, 2017. / Hibiscus sabdariffa is an under-utilised plant that has been reported to have great potential in the pharmaceutical and nutraceutical industries. The vibrant red pigment indicates a source of anthocyanins that could be produced into a food colourant with additional nutritional benefits however stability is a hindering factor. The crude anthocyanins were extracted from dried calyces by means of four different acidified ethanol and methanol solvent systems to determine the maximum crude anthocyanin yield. The crude extracts were analysed under the following parameters; heat, light, pH stability and degradation kinetics, which included thermal degradation and DPPH radical scavenging ability. Two synthetic colourants were analysed based on the stability parameters; heat, light and pH and compared with the natural H. sabdariffa crude extracts. Each of the four crude extracts were analysed for the total phenolic content using Folin Ciocalteu’s method. The DPPH and FRAP assays were used to determine the radical scavenging activity of the extract with the highest yield. The identification and quantification of the crude anthocyanins were carried out using HPLC-DAD. The highest crude anthocyanin yield of 19.92% was observed by HCl acidified ethanol extract Acetic acid/water/methanol extract produced the lowest yield of 8.72%. The stability results showed that pigment retention of samples heated at 80˚C had a greater decrease over time than those heated at 50˚C. The pH stability of samples incubated for 7 days indicated that crude anthocyanins degraded slower at acidic pH, which is in keeping with reported literature therefore this extract, should be added to foods with lower pH. Light stability showed slower degradation in dark incubated samples resulting in 84% pigment retention after a 10 day period. Synthetic colourants proved to be superior, as they had showed better stability than the natural colourant under the same conditions. Half-life of thermally treated samples showed a decrease upon heating, colour was also affected as samples became dull and murky. DPPH of thermal treated samples showed a decline in radical scavenging activity from 70 to 85˚C and thereafter an increase was observed between 85 and 90˚C, this could be due to the release of degradation products that have antioxidant capability. Solvent systems did not have an effect on the total phenolic content of crude extracts as no significant difference was observed by each of the H. sabdariffa crude extracts contained an average of 54.67 mg/ml GAE. The radical scavenging ability assessed by the DPPH and FRAP assays showed 53.75% and 57.51% radical scavenging ability respectively. Although the synthetic colourants showed better stability, a natural food colourant from H. sabdariffa can still be beneficial as it has potential to be applied into foods that contain low pH such as jelly and yoghurt. The additional benefits that natural food colourants possess aid in the marketability of the product. / M

No description available.

The purpose of this investigation was to prepare a number of coloring matters by condensing vanillin with para-methoxyacetophenone, meta-nitroacetophenone, and para-bromoacetophenone, and to prepare another group by condensing methyl salicylate with acetophenone, para-methoxyacetophenone, meta-nitroacetophenone, and ortho-hydroxyacetophenone. Ethyl salicylate and para-methoxyacetophenone were condensed as a check.

Indiana University-Purdue University Indianapolis (IUPUI)

No description available.

A graph is (t+1)-critical if it is not t-colorable, but every proper subgraph is. In this thesis, we study the structure of critical graphs on higher surfaces. One major result in this area is Carsten Thomassen's proof that there are finitely many 6-critical graphs on a fixed surface. This proof involves a structural theorem about a precolored cycle C of length q. In general terms, he proves that a coloring, c, of C, can be extended inside the cycle, or there exists a subgraph H with at most a number of vertices exponential in q such that c can not be extended to a 5-coloring of H. In Chapter 2, we proved an alternative proof that reduces the number of vertices in H to be cubic in q. In Chapter 3, we find the nine 6-critical graphs among all graphs embeddable on the Klein bottle. In Chapter 4, we prove a result concerning critical graphs related to an analogue of Steinberg's conjecture for higher surfaces. We show that if G is a 4-critical graph embedded on surface S, with Euler genus g and has no cycles of length four through ten, then G has at most 2442g + 37 vertices.

In recent times an evident trend in hardware is to opt for multi-core CPUs. This has lead to a situation where an increasing number of sequential algorithms are parallelized to fit these new multi-core environments. The greedy Multi-Coloring algorithm is a strictly sequential algorithm that is used in a wide range of applications. The application in focus is on decomposition by graph coloring for preconditioning techniques suitable for iterative solvers like the and methods. In order to perform all phases of these iterative solvers in parallel the graph analysis phase needs to be parallelized. Albeit many attempts have been made to parallelize graph coloring non of these attempts have successfully put the greedy Multi-Coloring algorithm into obsolescence. In this work techniques for parallel graph coloring are proposed and studied. Quantitative results, which represent the number of colors, confirm that the best new algorithm, the Normann algorithm, is performing on the same level as the greedy Multi-Coloring algorithm. Furthermore, in multi-core environments the parallel Normann algorithm fully outperforms the classical greedy Multi-Coloring algorithm for all large test matrices. With the features of the Normann algorithm quantified and presented in this work it is now possible to perform all phases of iterative solvers like and methods in parallel.

published_or_final_version / Botany / Doctoral / Doctor of Philosophy