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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Production and Characterization of a Novel Extracellular Polysaccharide Produced by Paenibacillus velaei, Sp. Nov

Sukplang, Patamaporn 08 1900 (has links)
Paenibacillus velaei, sp. nov. is a soil bacterium capable of producing an unusually large amount of exopolysaccharide (EPS). The EPS contains glucose, mannose, galactose and fucose in a molar ratio of 4:2:1:1. The molecular weight of the EPS is higher than 2x106. The viscosity of 1% EPS is 1300 cP when measured at a shear rate of 1 sec-1. Physiological parameters for optimal production of the EPS were studied and it was found that 1.4 g dry weight per 1 l of medium was produced when the bacteria were grown at 30EC and the pH adjusted at 7± 0.2 in a medium containing glucose as the carbon source. Growing the bacteria on different carbon sources did not alter the quantity or the composition of the EPS produced. No toxicity effects were observed in mice or rats when EPS was administered in amounts ranging from 20 to 200 mg per kg body weight. The data obtained from physical, chemical and biological properties suggest that the EPS may be employed in several industrial and environmental applications. It is an excellent emulsifier, it holds 100 times its own weight in water, it is not toxic, and it can be used to remove mercury, cadmium and lead from aqueous solutions.
12

Factors Affecting Carbohydrate Production and Loss in Salt Marsh Sediments of Galveston Bay

Wilson, Carolyn E. 2009 August 1900 (has links)
Benthic microalgae (BMA) living within the surface sediment of salt marshes are highly productive organisms that provide a significant proportion of organic carbon inputs into estuarine systems. BMA secrete extracellular carbohydrates in the form of low molecular weight carbohydrates and extracellular polymeric substances (EPS) as they migrate within the sediment. EPS plays an important role in the structure and function of BMA biofilms in shallow-water systems as EPS affects habitat structure, stabilizes the sediment, reduces sediment erosion, and is a carbon source for organisms. This study looked at the effect of nutrients and carbohydrate additions on BMA biomass, bacterial biomass, carbohydrate production, and glycosidase activity in the surface 5 mm of intertidal sediment in a subtropical salt marsh (Galveston Bay, Texas). Nitrogen and phosphorus were added to cores collected from the salt marsh and incubated in the lab over four days. Very little change was seen in the biomass of the benthic microalgae or in the different carbohydrate fractions with the added nutrients. The mean chlorophyll a concentration was 13 +/- 5 ug g-1 sediment, the mean saline extractable carbohydrate concentration was 237 +/- 113 ug g-1 sediment, and the mean EPS concentration was 48 +/- 25 ug g-1 sediment. The chlorophyll a and saline extractable carbohydrate concentrations initially decreased over the first 24 hours, but then increased over the rest of the experiment, indicating a possible species compositional shift in the BMA. With no major response with nutrient additions, it is likely that a different environmental factor is limiting for the growth of the benthic microalgae, and therefore the production of sEPS, in this salt marsh. A series of experiments was conducted in situ by adding glucose, alginic acid, and phosphorus to sediment within experimental plots. Samples were taken periodically over three to seven days to determine the biomass of the microbial community, enzyme activities and kinetics, and changes in the concentrations of several sediment carbohydrate pools. u-glucosidase activities (15 +/- 3 nmol g-1 h-1) were significantly higher than u-xylosidase (6 +/- 2 nmol g-1 h-1) and u-galactosidase (8 +/- 2 nmol g-1 h-1) activities within the sediment, and there was no suppression of u-glucosidase activity measured with the glucose addition. These data represent the first measurement of u- xylosidase and u-galactosidase activity in intertidal sediment dominated by BMA. Although preliminary experiments suggested a possible phosphorus limitation within the sediment, there was little change in the bacteria abundance or the benthic microalgae biomass when phosphorus was added in situ. This study begins to illustrate the dynamics of carbohydrate production and loss in this salt marsh, and the ability for the microbial community in the salt marshes of Galveston Bay to adjust to the nutrient and carbohydrate treatments.
13

The study of regional civic aviation market in china

Chen, Fu-chuan 22 June 2007 (has links)
The China¡¦s aviation market has the hugest potential guest group in the world and the special geographical environment disadvantage developing surface transportation, in addition, the economic reform in recent years effect regional civic aviation market positive significantly. In fact, the China regional civic aviation really had some unprecedented progress, and the regional civic aviation environment also had certain improvement, however, the further development for China regional civic aviation was facing another challenge. The research discovered that, the China regional civic aviation got different character. For example, the China¡¦s northwest area regional civic aviation start more early; The southwest province regional civic aviation develop more quickly; The southeast area regional civic aviation passenger has the high payment ability. In sum, the China regional civic aviation market is ubiquitous, how to choose correct market policy and proper regional civic airplane and the network would lead regional civic aviation to obtain the political and economic benefit
14

Europeisk patenträtt i förändring / Changes in the European Patent Law

Lilja, Henrik, Sjöström, Anna January 2014 (has links)
Efter många års kompromissande kommer ett Europeiskt patent med enhetlig verkan (EU-patent) att införas. Tillsammans med skapandet av en enhetlig domstol, kallad Unified Patent Court (UPC), kommer EU-patentet säkerställa en enhetlig patenträttslig tillämpning i alla deltagande länder. I denna uppsats görs först en genomgång av vad EU-patent respektive patent enligt The European Patent Convention (EPC-patent) innebär och hur tvister hanteras. Sedan förs en diskussion kring skillnaderna och deras påverkan på ett fiktivt företag inom bilsäkerhetsbranschen.EU-patentet kommer materiellt inte särskilja sig i någon större utsträckning från det nuvarande EPC-patentet. De stora skillnaderna kommer istället att vara den förenklade ansökningsprocessen, minskade kostnader och det geografiska skyddsomfånget. Vid beviljande av EU-patent får patentet verkan i samtliga deltagande länder. Systemet kommer emellertid medföra en stor osäkerhet till en början eftersom det är nytt och därmed saknas praxis. Dessutom finns en viss rädsla för så kallade patenttroll som med EU-patent kommer få möjlighet att tillskansa sig patent för nästan hela EU.UPC förväntas innebära minskade kostnader i samband med rättsprocesser. Dessutom är målet att förutsägbarheten och följdriktigheten ska vara lika hög oavsett i vilket av de deltagande länderna rättsprocessen sker. Än en gång är dock bristen på praxis ett problem eftersom EU-ländernas praxis inom patentfrågor ser olika ut och det kan inte förutsägas hur domstolen kommer förhålla sig till dessa skillnader.För det fiktiva företaget är förenklingen och de minskade kostnaderna med EU-patentet lockande. De osäkerheter som finns innan EU-patentet och UPC har hunnit utvecklats ordentligt och praxis byggts upp innebär emellertid en risk. De ekonomiska fördelarna kommer förmodligen inte att kunna väga upp risken under de första åren. Därför kommer företaget troligen att avvakta för att se att EU-patentet och framförallt UPC erbjuder ett tillfredsställande skydd.
15

La place des jeux traditionnels dans l'EPS : analyse socio-historique de 1891 à nos jours; le cas de la Gironde

Assaf, Tarek 03 May 2010 (has links)
Quelles raisons écartent les jeux traditionnels des séances d’éducation physique et sportive (EPS) ? Doit-on y voir l’absence d’utilité éducative ? Il serait vain de perdre du temps en recourant à des pratiques pédagogiques dépassées. Les jeux, c’était avant. Maintenant on fait du sport. Le jeu dérange car il suscite des émotions envahissantes et des réactions mutines que le sport réussit à endiguer. La thèse traite de la place des jeux traditionnels en EPS et dans les textes officiels depuis la naissance de celle-ci à la fin du XVIII siècle. Ce travail de recherche porte aussi sur la signification des jeux et leurs intérêts, du point de vue des philosophes, des psychologies, des anthropologies. De même, l’approche des jeux traditionnels ou la part de la motricité est central s’appuie sur les concepts et les modèles proposés par Pierre Parlebas. Enfin, nous proposons une enquête visant à mettre en évidence la place mineure occupée par les jeux traditionnels dans le monde scolaire. Pourquoi le jeu est-il mis à l’index en EPS ? Le manque d’intérêt pour ces jeux, qui s’accroit à mesure que l’élève se déplace dans sa scolarité et grandit est mis en relation avec les variables sociodémographiques, avec l’influence du sport et le poids des normes didactiques. Sont également retenues comme variables indépendantes la formation initiale des enseignants, le jugement porte par ceux-ci sur l’engagement énergétique des élèves, et l’influence de la modernité technologique. / What reasons justify the absence of traditional games in scholastic sessions of Physical and Sports Education (PSE)? Should we witness the absence of an educational tool without questioning the reasons behind its absence? Moreover, it would be unproductive to spend time resorting to outdated sports practices. Games belong to the realms of the past. Nowadays, we play sports. While games are disruptive because they provoke uncontrollable emotions, sports activities contain these unruly emotions and helps in channeling them out. This dissertation studies the importance of traditional games in the PSE and in official textbooks since the creation of traditional games at the end of the eighteenth century. This research study also traces the significance and effects of games as outlined by philosophers, psychologists, and anthropologists. Moreover, this study follows Pierre Palebas’s model that highlights the centrality of motricity in the analysis of traditional games. I also propose in this study the creation of a survey that quantitatively proves the marginal position that traditional games occupy in the scholastic world. Why are games, for instance, relegated to the appendices of the PSE? The lack of interest in these traditional games—a lack which presupposes that a student shifts interests in their academic progress as they grow up—is put in juxtaposition with sociodemophrahic variables, in addition to the influence of sports in general and the effect of didactic norms. This study considers all these factors as independent variables influenced by the training of instructors, the physical engagement of students, and the overall influence of modern technology.
16

Soluble Microbial Product Characterization of Biofilm Formation in Bench-Scale

Mines, Paul 12 1900 (has links)
The biological process known as activated sludge (AS) in conjunction with membrane separation technology for the treatment of wastewater has been employed for over four decades. While, membrane biological reactors (MBR) are now widely employed, the phenomenon of membrane fouling is still the most significant factor leading to performance decline of MBRs. Although much research has been done on the subject of MBR fouling over the past two decades, many questions remain unanswered, and consensus within the scientific community is rare. However, research has led to one system parameter generally being regarded as a contributor to membrane fouling, extracellular polymeric compounds (EPS). EPS, and more specifically, the soluble fraction of EPS known as soluble microbial products (SMP), must be further investigated in order to better understand membrane fouling. The biological activity and performance of the MBR is affected by myriad operational parameters, which in turn affects the SMP generated. A commonly varied operational parameter is, depending on the specific treatment needs of a MBR, the sludge retention time (SRT). This study aims to characterize the SMP in three bench-scale MBRs as the SRT is gradually lowered. By studying how the SMP change as the operation of the system is altered, greater understanding of how SMP are related to fouling can be achieved. At the onset of the study, a steady state was established in the system with a SRT of 20 days. Upon stabilization of a 20 day SRT, the system was gradually transitioned to a five and a half day SRT, in stepwise adjustments. Initially, both the trans-membrane pressure (TMP) and the SMP concentrations were at relatively low values, indicating the presence of minimal amounts of biofilm on the membrane surfaces. As the system was altered and more activated sludge was wasted from the reactors, the SRT inherently decreased. As the lower SRT was transitioned and established, the data from TMP measurements, as well as the results from SMP determination, confirmed the development of increased amounts of biofilm formed. An apparent relationship was observed between the operational condition of a lower SRT and the SMP found in the system.
17

INVESTIGATION OF TRANSPORT AND DEGRADATION PROCESSES OF POLYCYCLIC AROMATIC HYDROCARBONS IN BIOFILM

PFARR, ELENA CHRISTINE January 2004 (has links)
No description available.
18

The Effect of Nitrates, pH, and Dissolved Inorganic Carbon Concentrations on the Extracellular Polysaccharide of Three Strains of Cyanobacteria Belonging to the Family Nostocaceae

Horn, Kevin J. 02 July 2008 (has links)
Three strains of cyanobacteria (Anabaena PCC7120, A. variabilis and Nostoc commune), all belonging to the family Nostocaceae, were found to be capable of modulating the production and chemical composition of extracellular polysaccharides (EPS) in response to carbon and nitrogen availability as well as pH. While the carbohydrate compositions of the glycans produced by the different organisms were indicative of their recent evolutionary divergence, there were measurable differences that were dependent upon growth conditions. The EPS resulting from biofilm growth conditions was reduced in glucuronic acid levels in both Anabaena variabilis ATCC 29413 and Anabaena PCC 7120. Under planktonic conditions, the glycan from A. variabilis contained glucuronic acid when grown in nitrate-free BG-11₀ medium whereas A. PCC 7120 produced similar levels in standard BG-11 medium. This suggests that phylogeneticallyrelated cyanobacteria respond very differently to changes in their local environment. The pH of BG-11 cultures increased to 9-10 for all three strains of cyanobacteria. The increase resulted in an increase in the amount of dissolved inorganic carbon available in the medium, creating an imbalance in the carbon-nitrogen ratio, with the complete consumption of 17.65 mmol L⁻¹ nitrates raising the pH to near 10 in BG-11 medium. While increased carbon availability has been shown to induce capsulated morphologies in strains of cyanobacteria, only Nostoc commune DRH-1 exhibited this behavior, and only when grown in BG-11 medium. Carbon and nitrogen availability as well as pH modulate the monosaccharide composition of the glycan generated by cyanobacteria investigated. The different characteristics of the glycans produced can affect the survivability of the organisms and the community structure of cyanobacterial biofilms and microbial mats found in nature. As cyanobacteria are ubiquitous organism both now and in the past, they play a pivotal role in the biological and geological processes of the Earth, controlling the availability and cycling of carbon and nitrogen both actively and passively. / Master of Science in Life Sciences
19

Copper in the Urban Water Cycle: Sources and Sinks, Benefits and Detriments, and Corrosion in Soft Waters

Sprague, Nicolle Marie 20 May 1999 (has links)
In recent years, stringent world-wide regulation of copper in drinking water, wastewater discharge and sludge has prompted utilities to carefully evaluate copper sources and sinks, benefits and detriments, and mitigation. This work compiled the individual efforts of researchers and utilities to provide a basis for holistic decision-making. Mass balances suggest that between 14-61% of copper in wastewater originates from home plumbing. Dosing of pure copper sulfate "root killer" by consumers, which is of unlikely value, accounted for up to 27% of copper inputs. Removal of copper in wastewater treatment ranged from 24-90%, suggesting a potential for optimization of these processes if desired. Finally, though utilities are pressured to reduce copper inputs at all stages of the urban water cycle, substantial benefits including human and wastewater bacteria micro-nutrition, water disinfection and algae control should not be overshadowed. To better understand copper inputs from corrosion in soft waters, a 12 month study was executed. Free chlorine (0.7 mg/L) was determined to have minimally adverse effects on copper release at pH 9.5 but no significant effect at pH 7.0, and higher temperatures usually increased copper release. Organic matter including soluble and particulate NOM, sodium alginate, and gum xanthan, tended to worsen copper release. Their direct effects included complexation and mobilization of pre-existing copper scale as particulates. Indirect effects were also discovered, including a propensity of gum xanthan and alginate to decrease pH, increasing copper release, and also to produce a microbiologically unstable water, decreasing the dissolved oxygen necessary for fueling corrosion reactions. The range of organic matter effects could be placed within a unified conceptual framework. / Master of Science
20

CRISPR3 Regulates Exopolysaccharide Production in Myxococcus xanthus

Wallace, Regina A. 10 October 2013 (has links)
Myxococcus xanthus, a model organism for studying development and Type IV pili (T4P), harbors three Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) on its chromosome. CRISPR systems, which function as an adaptive immune system in prokaryotes, are classified into three types based on CRISPR-associated genes. Evidence suggests that these three types mediate immunity slightly differently. M. xanthus CRISPR1 and CRISPR2 are Type I systems while CRISPR3 is a Type III-B system. In a genetic screen, a mariner transposon insertion in the 13th spacer of CRISPR3 (3SP13) was found to restore exopolysaccharide (EPS) production to a pilA mutant. Since the deletion of CRISPR3 failed to suppress a pilA mutation and expression of CRISPR3 from a heterologous promoter led to pilA suppression, it was concluded that the 3SP13 transposon insertion is a gain-of-function mutation. Deletion of the adjacent Repeat Associated Mysterious Proteins (RAMP) genes indicated that they are essential for the 3SP13 transposon insertion to suppress pilA, providing evidence that Type III-B systems may be involved in the regulation of chromosomal genes. We suggest that one of the spacers, once expressed and processed, may inhibit the expression of a negative regulator of EPS production in M. xanthus. / Master of Science

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