Plant imagery abounds in Elizabeth Barrett Browning's novel-poem, Aurora Leigh, and critical readings have not thoroughly explored the meaning of and intent behind that imagery. Plant metaphor and images in Aurora Leigh are used to challenge the concept of Victorian women's inherently inferior "nature" and to present an argument for female equality. When traced throughout the work, plant imagery foreshadows Aurora and Marian's ultimate personal independence and familial harmony and helps the reader to understand the poem's controversial ending. Ties to three of Browning's literary influences in the selection of plant images are explored: Emanuel Swedenborg, Mary Wollstonecraft, and Samuel Taylor Coleridge. Each of these three understood and used nature imagery to significant effect in their own writings, and Browning adopted and developed those images in her work.

Thesis (Ph. D.)--University of Chicago, 1999. / Includes abstract. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1980. / Bibliography: leaves 100-107.

Copper metallothionein (Cu-MT) was extracted from the induced biomass of Aspergillus niger. The crude extract (FI), obtained by cell homogenization, was partially purified by heat treatment (FII) and ultrafiltration (FIII). Further purification of the Cu-MT extract by affinity chromatography resulted in three major fractions, FIVa, FIVb and FIVc, of which fraction FIVc was considered to be the Cu-MT extract fraction. Fraction FIVc was re-chromatography on affinity chromatography and the eluted fraction showed a single peak (FIVc'). Spectrophotometric analysis of fraction FIVc' demonstrated a maximum absorption peak at 268 nm. Native and denatured electrophoretic analysis of fraction FIVc ' showed the presence of a single band with an estimated molecular weight of 9.5 and 10.0 kDa, respectively. Inhibition of mushroom tyrosinase (PPO) by the Cu-MT extracts was investigated, using selected phenolic substrates, including catechin, chlorogenic acid, catechol, 4-methylcatechol, caffeic acid, L-3,4-dihydroxyphenylalanine, 3,4-dihydroxyphenylacetic acid, 3-( p-hydroxyphenyl) propionic acid, p-hydroxyphenylpyruvic acid, p- and m-cresol. The results showed that the inhibitory effect of the Cu-MT extract increased with the degree of purification. The results revealed that the Cu-MT extracts were effective inhibitors of PPO activity and the best inhibitory effect was demonstrated with catechin as substrate; however, PPO activity was not inhibited by the Cu-MT extract when p-hydroxyphenylpyruvic acid and p- and m-cresol were used as substrates. The results also showed that the Cu-MT extracts exhibited different types of inhibition, including mixed, competitive and uncompetitive on PPO activity. In addition, the experimental findings indicated that the nature and degree of enzymatic inhibitions by the Cu-MT extracts were dependent upon the structural nature of the substrates as well as the methods including, spectrophotometer and polarograph, used for the detection of enzyme

Two natural enzymatic browning inhibitors, copper-metallothionein (Cu-MT) and polyphenol esterase (PPE), were obtained from A. niger and investigated. Reflectance measurements, expressed as L (lightness variable) and a (red to green degree of color) were used to compare, over extended periods of time, the relative inhibitory effectiveness of Cu-MT and PPE to those observed with the use of selected chemicals including ascorbic acid (AA), citric acid (CA), ethylenediaminetetraacetic acid (EDTA), sodium bisulfite (NaHSO3) and 4-hexylresorcinol (4HR), in the prevention of browning on the cut surfaces of selected food products such as apple and potato slices as well as freshly prepared apple juice. Treatment of each food product required an optimum concentration of the selected inhibitor for the inhibition of browning. (Abstract shortened by UMI.)

No description available.

A crude enzyme extract (FI) of polyphenol esterase (PPE), obtained from the microbial culture of Aspergillus niger, was partially purified by ammonium sulfate precipitation. The partially purified fraction (FII) was subjected to further purification by ion-exchange chromatography, which resulted in five separated fractions, FIIIa, FIIIb, FIIIc, FIIId and FIIIe), where FIIIa showed the highest PPE activity towards chlorogenic acid, as substrate. The biocatalysis of the PPE with a wide range of mono- and diphenols, as substrates, was shown to inhibit mushroom tyrosinase (PPO) activity. Fraction FIIIa exhibited an inhibitory effect, measured spectrophotometrically, on PPO activity with the monophenols, including 4-hydroxyphenylpyruvic acid and m- and p-cresols and the diphenols, including chlorogenic acid, catechin, 3,4-dihydroxyphenylacetic acid (DHPAA), L-3,4-dihydroxyphenylalanine (L-DOPA), 4-methylcatechol, catechol and caffeic acid; however, using the polarographic method, the inhibition of PPO activity by PPE biocatalysis occurred with the diphenols but not with the monophenols. The selected enzymatic fraction FIIIa was further purified, using size-exclusion chromatography, which resulted in three fractions FIVa, FIVb and FIVc. Although fraction FIVc contained the highest PPE activity, it showed a lack of enzyme stability. Fraction FIIIa was therefore, subjected to further purification by hydrophobic interaction chromatography thereby yielding fractions FVa, FVb, FVc, FVd, FVe, FVf and FVg, where fraction FVc showed the highest PPE activity. The denatured electrophoretic analysis of fraction FVc showed the presence of one major band, with a molecular weight of 60 kDa. The successive purification of PPE resulted in a marked increase in the inactivation of PPO activity with diphenols, as demonstrated by both the lower I50 and inhibition dissociation constant (Ki) values. The purified fraction FVc was shown to exhibit, spectrophotometrically, a competitive and un

The latest generation of fighter aircraft utilizes a 270Vdc power system [1]. Such high voltage DC power systems are difficult to protect with conventional circuit breakers because the current does not automatically go to zero twice per cycle during a fault like it does in an AC power system and thus arcing of the contacts is a problem. Solid state power controllers (SSPCs) are the solid state equivalent of a circuit breaker that do not arc and which can respond more rapidly to a fault than a mechanical breaker [2]. Present SSPCs are limited to lower voltages and currents by the available power semiconductors [8,9]. This dissertation presents design and experimental results for a SSPC that utilizes SiC power JFETs for the SSPC power switch to extend SSPC capability to higher voltages and currents in a space that is smaller than what is practically achievable with a Si power switch. The research started with the thermal analysis of the SSPCs power switch, which will guide the development of a SiC JFET multi-chip power module to be fabricated by Solid State Devices Inc. (SSDI) using JFETs from SiCED and/or Semisouth LLC. Multiple multi-chip power modules will be paralleled to make the SSPC switch. Fabricated devices were evaluated thermally both statically and dynamically and electrically both statically and dynamically. In addition to the SiC module research a detailed design of the high voltage SSPC control circuit capable of operating at 200andamp;ordm;C was completed including detailed analysis, modeling and simulations, detailed schematic diagrams and detailed drawings. Finally breadboards of selected control circuits were fabricated and tested to verify simulation results. Methods for testing SiC JFET devices under transient thermal conditions unique to the SSPC application was also developed.

This thesis attempts to characterize the musicality of Robert Browning's poetry. There has been much debate about whether or not Browning may be said to be a musical poet, but neither side has effectively characterized the musicality or lack thereof in his poetry. This study does not concentrate on Browning's "philosophy" of music, nor on the musical allusions in his poetry. Instead it attempts to identify aspects of Browning's art that share an affinity with music. / First, the state of music in nineteenth-century England is briefly discussed, followed by a discussion of Browning's musical background and an attempt to identify some general characteristics of musical poetry. The balance of the study is devoted to a discussion of the musicality of ten poems, among them "A Toccata of Galuppi's" and "Master Hugues of Saxe-Gotha". Emphasis is placed on these last two poems' ability to approximate a musical form: the toccata and fugue in the first, and the fugue in the second. The study concludes with a more general discussion of music in Browning's poetry.

Digestive proteases were isolated from the pancreas of the stomachless cunner fish (Tautogolabrus adspersus) and characterized in terms of their physicochemical properties, their ability to hydrolyze native pectin methylesterase (PME) from orange and polyphenol oxidases (PPO) from mushroom and the ability of the cunner enzyme(s) to maintain the stability of orange juice cloud. / The cunner trypsin fraction exhibited exceptional capacity to hydrolyze native proteins versus the bovine trypsin. Incubation of native PME with cunner or bovine trypsin resulted in a loss of 75% or 35% in PME activity respectively. Similarly, a 75% or 55% loss in PPO activity was observed after treatment with cunner and bovine trypsin respectively. Bovine trypsin, however, hydrolyzed the heat-denatured PME and PPO better than the cunner trypsin. Also, there was no reactivation of both PME and PPO activity after treatment with either the cunner or bovine enzyme during storage at 4$ sp circ$C for 3 weeks. However, PPO retained up to 20% or 50% of the initial activity after treatment with cunner or bovine trypsin, respectively. / A 3 x 3 factorial design involving the factors of temperature, enzyme concentration and incubation time carried out gave an r$ sp2$ of 0.92 and 0.95 for cunner and bovine trypsin treated PME respectively. On the other hand, an r$ sp2$ of 0.91 and 0.94 was obtained for the combined effects using cunner and bovine trypsin for PPO inactivation. Validation of the model of PME inactivation measured as the % cloud remaining revealed that the cunner trypsin fraction upheld the cloud stability of cloud juice better than bovine trypsin, with cunner trypsin retaining more than 90% of the cloud whereas the juice treated with bovine trypsin only resulted in a 70% retention of the juice cloud. (Abstract shortened by UMI.)