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Role Of A Carboxyl-Terminal Helix In The Assembly, Interchain Interactions, And Stability Of Aspartate Transcarbamoylase, Cynthia B. Peterson, H. K. Schachman Jan 1991

Role Of A Carboxyl-Terminal Helix In The Assembly, Interchain Interactions, And Stability Of Aspartate Transcarbamoylase, Cynthia B. Peterson, H. K. Schachman

Faculty Publications

The six individual catalytic polypeptide chains within the two catalytic trimers of Escherichia coli aspartate transcarbamoylase (ATCase; EC 2.1.3.2) are folded into two discrete structural domains interconnected in part by helix 12, which comprises residues 285-305 and is located near the carboxyl terminus of the chain. The essential role of this helix in folding of the chains and their assembly into ATCase was demonstrated by introducing a stop codon at the position corresponding to amino acid 284, 291, or 299. Cells containing these mutations are pyrimidine auxotrophs lacking ATCase-like protein in cell extracts. In contrast, stable active enzyme is formed …

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Lsu General Catalog 1991-1992, Louisiana State University And Agricultural And Mechanical College Jan 1991

Lsu General Catalog 1991-1992, Louisiana State University And Agricultural And Mechanical College

LSU General Catalog

The LSU General Catalog describes all undergraduate and graduate departments and programs with degree requirements and courses offered for each one. The General Catalog includes information on registration and financial aid as well as academic services offered to all students.

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Comparison Of Rhizoctonia Foliar Blights Of Soybean With Respect To Infection Process, Double-Stranded Rna Components, And Evaluation Of Resistance., Chandrasekar S. Kousik Jan 1991

Comparison Of Rhizoctonia Foliar Blights Of Soybean With Respect To Infection Process, Double-Stranded Rna Components, And Evaluation Of Resistance., Chandrasekar S. Kousik

LSU Historical Dissertations and Theses

Infection cushions were formed in a similar manner on soybean leaves by Rhizoctonia solani AG-1 IA (aerial blight) and AG-1 IB (web blight) isolates, however, AG-1 IB produced more mucilagenous material. Leaf topography did not induce infection cushion formation. More infection cushions were formed by isolates of AG-1 IA and IB on collodion membranes placed over leaves of susceptible compared to resistant cultivars. Glucose and 3-O-methylglucose repressed disease severity caused by AG-1 IA and IB isolates to the same extent. However, when the solutions were applied 40 h or longer after inoculation, no repression was observed. Disease severity and number …

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Comparative Overwintering Capabilities Of Africanized And European Honey Bees., Jose Damaso Villa Jan 1991

Comparative Overwintering Capabilities Of Africanized And European Honey Bees., Jose Damaso Villa

LSU Historical Dissertations and Theses

The potential of tropical Africanized honey bees to survive through winter was investigated to predict their possible geographical range and density in the United States. Experiments were conducted in cold rooms, at high elevations in tropical mountains, and during a winter season in Germany. The performance and survival of isolated groups of workers and of intact Africanized colonies were compared with those of European origin, and in some experiments, with those of hybrid crosses. In cold rooms, groups of 40 g of Africanized workers exposed to air currents at 15$\sp\circ$C aggregated in different positions and in tighter conformations than European …

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The Morphology, Development, And Function Of Experimentally Induced Macrophage Aggregates In Rivulus Marmoratus., Wolfgang Klaus Vogelbein Jan 1991

The Morphology, Development, And Function Of Experimentally Induced Macrophage Aggregates In Rivulus Marmoratus., Wolfgang Klaus Vogelbein

LSU Historical Dissertations and Theses

Calyptospora funduli is a pathogenic coccidium that infects the liver and pancreas of estuarine killifishes belonging to the genus Fundulus. Experimental infection of the atypical fish host Rivulus marmoratus with this intracellular protozoan parasite caused the development of hepatic macrophage aggregates (MA's) and granulomas. The Rivulus/Calyptospora host-parasite system thus represents a new laboratory model for investigations of MA biology. In the present study, this model was used to: (1) examine the morphology and sequential development of the parasite-elicited hepatic MA's in R. marmoratus, (2) define the role that these structures play in the pathogenesis of an infectious disease process, and …

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Directed And Spontaneous Transfer Of College Developmental Reading Students' Textmarking Strategies., Deidra Williams Frazier Jan 1991

Directed And Spontaneous Transfer Of College Developmental Reading Students' Textmarking Strategies., Deidra Williams Frazier

LSU Historical Dissertations and Theses

The purpose of this study was to examine directed and spontaneous transfer of college developmental reading students' textmarking strategy use. Two males and two females enrolled in a developmental reading course at Louisiana State University participated. Participants were asked to use textmarking strategies in their introductory biology course. During scheduled meetings with the researcher, participants turned in their annotated material, discussed textmarking progress, and received feedback on the quality of their annotations. Students were also asked to reflect on strategy use in assigned journal entries. Participants were not asked to use textmarking strategies in any other content course in which …

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Rice Diseases And Disorders In Louisiana, D E. Groth Jan 1991

Rice Diseases And Disorders In Louisiana, D E. Groth

LSU Agricultural Experiment Station Reports

No abstract provided.

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Development Of An Advanced Thermospray Interfaced Hplc-Aas System For Speciation Studies Of Cadmium Species Excreted From Human Body Fluids: Interaction Between Metallothionein Cadmium And Zinc., Peter Ping Chang Jan 1991

Development Of An Advanced Thermospray Interfaced Hplc-Aas System For Speciation Studies Of Cadmium Species Excreted From Human Body Fluids: Interaction Between Metallothionein Cadmium And Zinc., Peter Ping Chang

LSU Historical Dissertations and Theses

A new technique has been developed to reveal different metal species at very low concentrations (lower ppb level) in human body fluids. Using this technique it was determined that urine contained many different species of cadmium and that perspiration contained many other species of cadmium. This indicated that there were two avenues for the elimination of cadmium from the body. Quantitative data showed that much more cadmium was eliminated through perspiration than urine and that the biological half life of cadmium in the body was less than 1.5 years--not 20-30 years as currently believed. Further, in vitro experiments showed that …

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A Neural Network Truth Maintenance System., Suresh Guddanti Jan 1991

A Neural Network Truth Maintenance System., Suresh Guddanti

LSU Historical Dissertations and Theses

A novel approach using Neural Networks has been developed to generate consistent labelling of facts in relation to a given set of rules. In the proposed system, facts are represented by neurons and their interconnections form the knowledge base. The Neural Network Truth Maintenance System(TMS) arrives at a valid solution provided the solution exists. A valid solution is a consistent labelling of facts. If a valid solution does not exist the network does not converge. An experimental setup was built and tested using conventional integrated circuits. The hardware design is suitable for VLSI implementation for large, real-time problems. The TMS …

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The Introduction Into Tobacco Plants Of Genes Which Encode Some Of The Natural Components Of The Humoral Immune Response Of Hyalophora Cecropia., Luis Julio Cesar Destefano Beltran Jan 1991

The Introduction Into Tobacco Plants Of Genes Which Encode Some Of The Natural Components Of The Humoral Immune Response Of Hyalophora Cecropia., Luis Julio Cesar Destefano Beltran

LSU Historical Dissertations and Theses

A number of plant pathogenic bacteria has been shown to be highly sensitive to SB-37, a derivative of cecropin B (one of the three cecropins from the giant silk moth Hyalophora cecropia). The lytic activity exhibited by SB-37 has been shown to increase up to twenty-fold in the presence of chicken egg white lysozyme. The cDNAs genes encoding SB-37, attacin E (another component of the humoral response of Hyalophora cecropia), and chicken lysozyme have been introduced into tobacco (var Xanthi) and potato (a new cultivar 86007) plants by Agrobacterium-mediated transformation using co-integrate and binary vectors. The genes were placed under …

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Characterization Of Double-Stranded Rna And Fungal Virus From Diaporthe Phaseolorum Var. Caulivora., Yong-Hwan Lee Jan 1991

Characterization Of Double-Stranded Rna And Fungal Virus From Diaporthe Phaseolorum Var. Caulivora., Yong-Hwan Lee

LSU Historical Dissertations and Theses

Fifty-two isolates of Diaporthe phaseolorum var. caulivora originating from eight different states of the United States were collected and grown on potato dextrose broth for 2-3 wk. Double-stranded RNA was extracted by two cycles of cellulose (CF-11) chromatography and electrophoresed on 6% polyacrylamide gel. Among all isolates tested, 28 (54%) contained at least one molecule of dsRNA. Molecular sizes of dsRNA ranged from 0.4 to 4.5 Kb, and seven different sizes of dsRNA were detected. The 4.5 Kb dsRNA did not have sequence homology with smaller dsRNAs (2.1, 1.8, and 1.4 Kb), suggesting that the smaller dsRNAs are not deletion …

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Studies In Fructofuranose Chemistry., Ronald Joseph Voll Jan 1991

Studies In Fructofuranose Chemistry., Ronald Joseph Voll

LSU Historical Dissertations and Theses

The glycolytic pathway enzyme phosphofructokinase (E.C. 2.7.1.11) has as its substrate and activator two different carbohydrate phosphate esters. Both are derivatives of D-fructose in the furanose ring form. This dissertation is divided into two chapters: the first deals with the conformational specificity of the active site and the second the structure of the activator. The compound 2,5-anhydro-3,4-O-(1,2-ethanediyl)-D-mannitol was designed to test the active site. The synthesis utilized a phase-transfer cyclo-dialkylation of a vicinal diol to yield a trans-fused 2,5,8-trioxabicyclo (4.3.0) nonane system. The final product was shown to exist in a locked conformation in solution by temperature dependent n.m.r. experiments …

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Metabolic Pathways Associated With Glycogen Storage In Chronically Active And Normal Skeletal Muscle., Robert James Talmadge Jan 1991

Metabolic Pathways Associated With Glycogen Storage In Chronically Active And Normal Skeletal Muscle., Robert James Talmadge

LSU Historical Dissertations and Theses

To determine the pathways used for glycogen synthesis in chronically active and normal muscle, muscles from C57B1/6J dy$\sp{\rm 2J}/$dy$\sp{\rm 2J}$(dy$\sp{\rm 2J}$) mice were evaluated biochemically and histochemically. The gastrocnemius muscle (GAST) of the dy$\sp{\rm 2J}$ mouse, a chronically active muscle, contained twice as much glycogen and lactate as control GAST. The dy$\sp{\rm 2J}$ triceps muscle (TRI), which is not chronically active, showed no elevation in glycogen content. An intraperitoneal injection of $\sp{14}$C-lactate resulted in increased incorporation of $\sp{14}$C into glycogen by dy$\sp{\rm 2J}$ compared to control GAST. Both normal and dy$\sp{\rm 2J}$ GAST incorporated $\sp{14}$C into glycogen in an in …

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Patterning The Past: History As Ideology In Modern Southern Fiction., Deborah Wilson Jan 1991

Patterning The Past: History As Ideology In Modern Southern Fiction., Deborah Wilson

LSU Historical Dissertations and Theses

In this study, I analyze the modes of historical representation in works by Robert Penn Warren, William Faulkner, Eudora Welty and Ellen Douglas. In the chapter on All the King's Men, a novel that exemplifies the masculine historical perspective of traditional Southern literature, I show how Warren defines history as a process moving toward a predetermined end and then structures the narrative so that the women characters are constantly positioned outside that definition. In the second chapter, I begin with Eudora Welty's The Robber Bridegroom, examining the ways she alters the traditional story line of American history by drawing attention …

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The Immunoepidemiology Of Lung Cancer And Smoking: Lymphocyte Subsets., Joan Peters Blackmon Jan 1991

The Immunoepidemiology Of Lung Cancer And Smoking: Lymphocyte Subsets., Joan Peters Blackmon

LSU Historical Dissertations and Theses

The relative proportions of lymphocyte subsets in the peripheral blood constitute a measure of immune status. Results of research to establish whether or not individuals with lung cancer differ in their lymphocyte composition have conflicted due to failure to control for factors other than cancer that affect lymphocyte balance. This study was designed to quantitatively estimate the effects of variables such as disease (lung cancer), smoking, age, circadian and circannual rhythms, and dietary factors on lymphocyte subsets. Questionnaires were given to 64 white males with primary lung cancer and 219 cancer-free white males and a blood sample was obtained. Lymphocytes …

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Structural And Functional Studies Of Carbohydrates., Shirish Trymbak Dhume Jan 1991

Structural And Functional Studies Of Carbohydrates., Shirish Trymbak Dhume

LSU Historical Dissertations and Theses

Plasmodium falciparum is the parasite responsible for a major loss of human life due to malaria. The biochemistry of invasion of the parasite into human red cells is the subject of much study and controversy. The receptor mediated endocytosis of the parasite into the red cells is postulated to involve at least two major receptors on the cells. Earlier work focussed on glycophorin of red cells as a likely receptor. The present study focussed on the role of erythroglycan, the N-linked carbohydrate chain of band 3 of human red cells in the invasion process. Erythroglycan showed high levels of inhibition …

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Genotype X Environment Interaction For Growth And Reproductive Traits In Beef Cattle., Louis Munyakazi Jan 1991

Genotype X Environment Interaction For Growth And Reproductive Traits In Beef Cattle., Louis Munyakazi

LSU Historical Dissertations and Theses

Data on eight different two breed combinations of calves produced in two locations (Louisiana and Nebraska) were analyzed to determine the magnitude of genotype x location interactions for gestation length (GESTLEN), birth weight (BWT), pre-weaning average daily gain (ADG) and weaning weight (WWT). Sire breed (SB), sire/SB and cow breed (CB) interactions with location (LOC) were the primary sources of variation of interest in the analysis of variance. The SB x LOC interaction was significant for all traits whereas the CB x LOC interaction was important only for ADG. The sire/SB x LOC interaction accounted for a significant amount of …

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Organic Matter Variation Within Depositional Sequences: Stratigraphic Significance And Implication To Petroleum Source Rock Prediction., Mark Alan Pasley Jan 1991

Organic Matter Variation Within Depositional Sequences: Stratigraphic Significance And Implication To Petroleum Source Rock Prediction., Mark Alan Pasley

LSU Historical Dissertations and Theses

Study of Eocene-Oligocene sediments in Alabama and Upper Cretaceous strata in New Mexico shows that organic facies deposited on the shelf change noticeably at surfaces associated with transgression of the shoreline. Organic matter in sediments below transgressive surfaces is dominated by well preserved terrestrial organic matter (phytoclasts) whereas sediments deposited on the shelf during transgression contain sparse, highly degraded phytoclasts. Shelf deposits associated with transgressions generally contain more hydrogen-rich organic matter than those deposited during regression. Sediments associated with starvation surfaces contain abundant amorphous nonstructured protistoclasts and rare, highly degraded phytoclasts. Well preserved phytoclasts increase in abundance in sediments overlying …

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Biological Treatment Of Hazardous Waste Sludges In Suspended Growth Systems For Removal Of Benzo(A)Pyrene And Other Polynuclear Aromatics., Robert E. Marks Jan 1991

Biological Treatment Of Hazardous Waste Sludges In Suspended Growth Systems For Removal Of Benzo(A)Pyrene And Other Polynuclear Aromatics., Robert E. Marks

LSU Historical Dissertations and Theses

The scope of this research project was to develop a bioremediation process for accelerated oxidation of bioresistant hazardous waste sludges in continuous flow sludge reactors. Benzo(a)pyrene (BaP) was selected as the target compound due its strong bioresistance, highly carcinogenic nature, extremely low aqueous solubility, and extremely low allowable release limits for land disposal. BaP is often a major hazardous organic component in many hazardous waste impoundments when source wastes have originated from either petroleum refining or associated petrochemical facilities. There is evidence that the biodegradation rate of high molecular weight polynuclear aromatic hydrocarbons (PNA's) is the rate limiting step in …

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Modeling The Effect Of Shale Heterogeneities On Hazardous Waste Transport In Deep Well Disposal Systems., Seung-Whee Rhee Jan 1991

Modeling The Effect Of Shale Heterogeneities On Hazardous Waste Transport In Deep Well Disposal Systems., Seung-Whee Rhee

LSU Historical Dissertations and Theses

The transport of hazardous wastes in heterogeneous confining layers was evaluated using numerical simulations. The expected configuration of the confining layers was defined by Monte Carlo techniques assuming a binary random structure composed of pure sand and pure shale zones. Flow and solute transport in the generated configuration was determined via a finite element model. The effective permeability under saturated steady-state flow was dominated by shale permeability for higher shale fractions ($>$0.65) and by sand permeability for lower shale fraction ($<$0.4). The results agreed well with the numerical result of Desbarats (1987) and the analytical results of Dagan (1979). The effective vertical permeabilities were found to be dependent on shale size and anisotropy. Application of the techniques to a well in Jefferson Parish, Louisiana suggested that a mean advective penetration into confining layer using the injection pressure as an upper bound to the driving pressure was only 3m over 10,000 years. Transport calculations assuming a constant pressure driving force over 10,000 years suggested solute transport was controlled by hydrodynamic dispersion (dispersion + diffusion) rather than advection for higher shale fractions. Transport calculations assuming active injection for only the first 100 years suggested solute transport was controlled by diffusion for higher shale fraction. Buoyancy effects associated with salinity and temperature variations were negligible for solute transport through confining layers with a shale permeability less than 0.01 md. The results of solute transport of hazardous wastes in heterogeneous confining layers suggested that confining layers greater than 300 ft in thickness with shale fractions of greater than 0.65 and shale permeabilities of less than 0.01 md would be expected to contain injected wastes for 10,000 years.

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In Vitro Culture Of Bovine Uterine And Oviduct Epithelial Cells., John Kevin Thibodeaux Jan 1991

In Vitro Culture Of Bovine Uterine And Oviduct Epithelial Cells., John Kevin Thibodeaux

LSU Historical Dissertations and Theses

A reliable procedure was developed to harvest purified populations of bovine uterine epithelial cells from the luminal endometrium that allowed cells to be maintained in vitro for multiple subpassages. This method allowed adequate numbers of cells for in vitro culture studies to evaluate uterine secretion rates, uterine-embryo interactions and a new embryo co-culture system. In a second study, cells were isolated from the uterus and oviducts collected from cattle on day of estrus, on d 4 to 6, d 8 to 10 and d 14 to 16 of the cycle to monitor growth and development following incubation in vitro. The …

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Factors Responsible For The Differential Growth Of Brucella Abortus In Bovine Trophoblasts., Luis Ernesto Samartino Jan 1991

Factors Responsible For The Differential Growth Of Brucella Abortus In Bovine Trophoblasts., Luis Ernesto Samartino

LSU Historical Dissertations and Theses

The interactions of bovine chorionic membrane explants (CAMs) as well as three different bovine trophoblastic cell lines with Brucella abortus were evaluated. The ability of B. abortus to infect and grow within the cells of these CAMs and within these cell lines was measured. In addition, prostanoid and hormone production by the trophoblastic cells after infection with B. abortus was measured. Internalization of B. abortus within the cells of CAMs derived from placentas from both 3-month-gravid cows and 7-month-gravid cows was similar. By 24 hours post-inoculation B. abortus replication in 7-months-derived CAMs was significantly greater than the replication occurring in …

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A Reading Of "A Good Man Is Hard To Find" And "A Curtain Of Green": The Influence Of Parable On Flannery O'Connor And Eudora Welty., Allison Carol Chestnut Jan 1991

A Reading Of "A Good Man Is Hard To Find" And "A Curtain Of Green": The Influence Of Parable On Flannery O'Connor And Eudora Welty., Allison Carol Chestnut

LSU Historical Dissertations and Theses

A Good Man is Hard to Find by Flannery O'Connor and A Curtain of Green by Eudora Welty are short story cycles harmonized by their marked imitation of the style and structure of parable. O'Connor added stories after initially sending the collection to the publisher and then rearranged them accordingly; her work represents a completed cycle. Welty's collection, published in an order different from their individual publications and their original placement in an early typescript, is an arranged cycle. Moreover, parabolic style and structure unify each cycle. A parable typically is a brief story told in the past tense, usually …

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Effects Of Chronic Administration Of Phenylbutazone On Reproduction In The Mare., Mareth Ellsworth Jan 1991

Effects Of Chronic Administration Of Phenylbutazone On Reproduction In The Mare., Mareth Ellsworth

LSU Historical Dissertations and Theses

Phenylbutazone is a non-steroidal anti-inflammatory drug that acts by inhibiting prostaglandin synthesis. Prostaglandins are associated with crucial aspects of reproduction. In 5 experiments, mares were used to test the effects of phenylbutazone on reproduction. In all experiments, treatment was 2 g phenylbutazone or 10 ml physiological saline intravenously(control). In Experiment I, 9 mares were phenylbutazone-treated for 180 consecutive days and teased. Ovaries were palpated and cyclicity was verified by circulating progesterone concentrations. Thirty-six cycles were evaluated. Mares were then divided into treatment and control groups. Estrous mares were artificially inseminated. Non-surgical embryo collection was performed 7 to 8 days post-ovulation. …

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Taxonomy And Biostratigraphy Of Sabinian Palynomorphs From The Wilcox Group (Paleocene-Eocene Epochs) Of Southwestern Louisiana., William Andrew Gregory Jr Jan 1991

Taxonomy And Biostratigraphy Of Sabinian Palynomorphs From The Wilcox Group (Paleocene-Eocene Epochs) Of Southwestern Louisiana., William Andrew Gregory Jr

LSU Historical Dissertations and Theses

Fifty conventional core samples from the Ragley Lumber #D1 well located in Allen Parish Louisiana (Sec 29, T5S, R7w) were analyzed for palynomorphs. The sediment was deposited during the Sabinian Provincial Stage (upper Paleocene-lower Eocene) in a marine environment as evidenced by the presence of in situ dinocysts and acritarchs in every sample. Terrigenous diversity of 129 taxa is comparable with marine palynomorph diversity of 46 taxa. Single sample diversity among the terrigenous palynomorph component (23-56 taxa) is comparable with single sample marine palynomorph diversity of 7-25 taxa. High terrigenous diversity intervals possibly indicate sourcing from multiple onshore environments or …

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On Bubble Columns. (Volumes I And Ii)., Nicholas William Geary Jan 1991

On Bubble Columns. (Volumes I And Ii)., Nicholas William Geary

LSU Historical Dissertations and Theses

There exists a narrow operating window in bubble columns where the motion is so gentle that the normally dominating forces of coalescence and breakup no longer define column conditions. This behavior is synonymous with operation in the bubbly flow regime. During experimentation, two distinct hydrodynamic regions were observed; close to the sparger, the liquid was well mixed, whilst in the remainder of the column a dispersive flow model was determined to be appropriate. In the entrance zone, the isotropic turbulence theories of Kolmogoroff adequately represented transport behavior. This finding implies that a churn-turbulent environment, wherein bubbles are continuously reformed, will …

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Radial Flow Chromatography In Compressed Pancake-Shaped Beds., Brian Keith Heft Jan 1991

Radial Flow Chromatography In Compressed Pancake-Shaped Beds., Brian Keith Heft

LSU Historical Dissertations and Theses

The separation of a methane/n-butane mixture was demonstrated using radial flow through compressed, pancake-shaped beds of fine alumina powder. The compacted stationary phase improved performance relative to an uncompressed sorbent by assuring flow uniformity through the bed, reducing band-broadening and tailing (by decreasing interstitial hold-up) and decreasing effective plate height (through an increase in the capacity ratio of the chromatograph). Dispersion was identified as the key dissipative effect in the prototype radial flow adsorber. An exact analytical solution derived for the transport equations describing such a device compared favorably with experimental data. The dispersion coefficients were found to be strong …

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Feedback Linearization Of Nonlinear Systems: Robustness And Adaptive Control., Weon Ho Kim Jan 1991

Feedback Linearization Of Nonlinear Systems: Robustness And Adaptive Control., Weon Ho Kim

LSU Historical Dissertations and Theses

Feedback linearization provides an effective means of designing nonlinear control systems. This method permits one to have an exactly equivalent linear system by using a coordinate transformation and state feedback. Once the nonlinear system is transformed to a linear system, one can proceed with well developed control technologies for linear systems. Feedback linearization is based on a model of the real system. If there is mismatch between the model and the real plant, feedback linearization does not yield an exactly linear system. The question of robustness then arises: will a controller based on the model be stable when applied to …

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Fluorescence Studies Of Phosphofructokinase From Bacillus Stearothermophilus., Soon-Jong Kim Jan 1991

Fluorescence Studies Of Phosphofructokinase From Bacillus Stearothermophilus., Soon-Jong Kim

LSU Historical Dissertations and Theses

Phosphofructokinase catalyzes the phosphorylation of $\beta$-fructose 6-phosphate (Fru-6-P) to $\beta$-fructose 1,6-bisphosphate. The first part of this dissertation shows that phosphofructokinase from Bacillus stearothermophilus (Bs-PFK) is a tetramer in the region pH 4.5-9.5 unlike the enzymes from mammalian sources, which exhibit association-dissociation reactions. Circular dichroism, steady-state fluorescence, and static and dynamic light scattering were used to study the conformational properties of the enzyme. Inactivation of the enzyme below pH 7.0 is not due to dissociation of the tetramer to dimers or monomers. In the second part, the fluorescence of the lone tryptophan was investigated by steady-state and time-resolved techniques. The decay …

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The Molecular Basis Of Imidazolinone Herbicide Resistance In Arabidopsis Thaliana Var. Columbia., Kanagasabapathi Sathasivan Jan 1991

The Molecular Basis Of Imidazolinone Herbicide Resistance In Arabidopsis Thaliana Var. Columbia., Kanagasabapathi Sathasivan

LSU Historical Dissertations and Theses

Acetolactate synthase (ALS) is a key regulatory enzyme in the biosynthetic pathway of leucine, isoleucine, and valine. ALS is inhibited by four classes of structurally unrelated herbicides viz. sulfonylureas, imidazolinones, triazolopyrimidines, and pyrimidyl-oxy-benzoate. To understand the molecular basis of imidazolinone resistance, the ALS gene was isolated from an imazapyr-resistant mutant GH90 of Arabidopsis thaliana (Haughn and Somerville, 1990. Plant Physiol. 92:1081-1085). DNA sequence analysis of the mutant gene demonstrated a single point mutation from G to A at the 1958th nucleotide of the ALS coding sequence (Sathasivan et al., 1990. Nucl. Acids Res. 18:2188). This would result in serine to …

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