Iron corrosion is the most important economic and aesthetic problem facing utilities. In the water distribution system, problems caused by iron corrosion include "red water", scale buildup, and pipe failures. It is necessary to improve our mechanistic understanding of anaerobic iron corrosion in order to better address these concerns. Experiments were conducted to investigate the effect of soluble constituents (Fe2+, PO43-, and NH4+) on H2 evolution during anaerobic iron corrosion. At pH 7.0 when sulfide was absent, variable Fe2+ did not have much influence on H2 release rates, whereas PO43- and NH4+ promoted H2 evolution. If present, soluble sulfide controlled H2 release rates in the solutions with Fe2+ or PO43-; however, NH4+ and S2- combined to inhibit H2 release. A simplistic empirical model was developed that fit data on corrosion rates from previous researchers studying effects of sulfate-reducing bacteria (SRB) on iron corrosion. As a whole, the experimental data and the model results support the notion that water quality controls iron corrosion rates in the presence of SRB. The practical relevance of previous research is somewhat in doubt given the atypical levels of nutrients used in relation to those actually present in water and wastewater. A second phase of research was aimed at exploring the equilibrium and kinetic aspects of iron corrosion in the presence of phosphate. The hypothesis that anaerobic iron corrosion is influenced by low pressure H2 (<1 atm) buildup was examined. At pH 2.75 and pH 7.0 in the presence of 100 mg/L P-PO43-, variations in H2 release were measured under different circumstances. Addition of PO43- formed a protective film, possibly vivianite Fe3(PO4)2, on the iron surface that eventually stopped H2 release. However, results were consistent with the idea that corrosion is an irreversible process that is relatively insensitive to low level H2 (<1 atm). Possible alternative explanations were provided to reconcile the past research data that purportedly demonstrated that removal of H2 increased corrosion rates. A reaction that caused "decay" of H2 in the presence of high phosphate was discovered that can not be readily explained. / Master of Science

Nineteen obese women were studied to determine the effects of two different exercise prescriptions which differed in the type of activity but were matched for total energy expenditure. All women met once per week for twelve weeks as a group to receive the same recommendations concerning dietary modification. A low fat, self selected diet of approximately 1200-1500 kcal was recommended. Ten women participated in a walking program four days/week (GP1) which progresses to 160 minutes per week at 70% HR max. The second group (GP2) of nine women did two days/week (up to 90 minutes/week) walking and two days/week resistance training (up to 90 minutes/week). The resistance training consisted of eight exercises, 8-15 repetitions, at 50-85% of 1 RM, and three sets. All exercises were supervised and attendance for all women was greater than 92% of all the sessions. Losses of body weight (BW) (-5.7 ± 1.1 kg and - 4.5 ± 1.0 kg for GP1 and GP2, respectively), body fat (-3.9 ± 1.1 kg and -4.9 ± 1.0 kg for GP1 and GP2 , respectively) and fat free mass (-2.1 ± .7 kg and -1.6 ± .9 kg for GP1 and GP2, respectively), and percent body fat (- 2.1 ± .7 and -1.5 ± .9 for GP1 and GP2, respectively) were significant over time for both groups with no significant differences between groups. However, GP1 tended to lose more percent body fat and FFM than GP2. Absolute RMR showed a nonsignificant decrease overtime for both groups (-139.7 ± 107.5 kcal/day and -48.1 ± 75.0 kcal/day for GP1 and GP2, respectively). RMR expressed per bodyweight (kg) or fat free mass was maintained for both groups over the experiment (+.4 RMR/kg and -1.1 RMR/FFM respectively for GP1 and +.6 RMR/kg and -.04 RMR/FFM respectively for GP2). In conclusion, the total energy cost of exercise rather than the type of activity seems most important in body composition and metabolic rate changes during weight loss. / Master of Science

Two chemical methods, multi-reducing end modification and bleach oxidation, were used to prepare polysaccharide aldehydes and ketones. Their derived hydrogels and microgels were made for potential drug-delivery applications. Polysaccharide aldehydes and ketones are reactive intermediates for adding other functional moieties through chemo selective reactions such as Schiff-base formation or reductive amination. The most widely used method to prepare polysaccharide aldehydes is periodate oxidation. However, this method impacts higher-order polysaccharide structure, decreases degree of polymerization (DP), and increases polysaccharide instability, leading to degraded mechanical properties. Developing a new method to prepare polysaccharide aldehydes while preserving DP, stability, and desirable physical properties is challenging. Inspired by the reactive reducing ends of polysaccharides, which are the anomeric carbons (at the chain end), one per natural polysaccharide molecule, that (for aldose-based polysaccharides) is in equilibrium between a ring-closed hemiacetal and an open-chain aldehyde form, we developed a novel method to prepare polysaccharide aldehydes by attaching monosaccharides to polysaccharide chains. Herein, we describe the approach of attachment through amination between amine group at the C2 position of the monosaccharide and carboxylic acid groups on polysaccharides. In this way, more reducing ends (C1 of the monosaccharide) can be introduced to the polysaccharides. We have chosen to call this new family of polysaccharides "multi-reducing end polysaccharides (MREPs)". We call this method "multi-reducing end modification". We then fabricated injectable, self-healing, fast gelling Schiff base hydrogels based on MREPs. Previous methods to fabricate Schiff base polysaccharide hydrogels usually required periodate oxidation which leads to degraded mechanical properties, with gelation time typically from minutes to hours. We employed acetic acid to induce fast gelation of our MREPs hydrogels within seconds. The Schiff base MREP hydrogels exhibited self-healing and injectable behavior with limited cytotoxicity, which is promising for future biomedical applications such as targeted drug delivery or tissue engineering. Microgels are dispersible but undissolvable colloids of three-dimensional polymer networks with numerous applications. We synthesized all-polysaccharide microgels (herein, we use the general term "microgels" to describe small gel particles of nanometer to micron diameters) using oxidized hydroxypropyl cellulose (Ox-HPC), carboxymethyl chitosan (CMCS), and calcium chloride. By tuning the calcium concentration, uniform microgels can be obtained with gel size in the hundreds of nanometers. Model amine-containing drugs such as picloram or p-aminobenzoic acid (pABA) can be chemically attached to Ox-HPC through Schiff base chemistry, creating imine bonds that are reversible in water, thereby permitting slow release. This class of all-polysaccharide microgels showed promising applications in agriculture, such as controlled release of agrochemicals. We anticipated that these strategies would benefit future polysaccharide chemistry research and permit synthesis of novel hydrogel or microgel systems with potential drug-delivery applications. / Doctor of Philosophy / Polysaccharides are long chains composed of sugar units ("sugar polymers"). Many natural-derived polysaccharides are sustainable, biodegradable and have low toxicity. Hydrogels are composed of porous solids and water, similar to the structure of human tissues. "Microgels" are used herein to describe small gels of nanometer to micron diameters. Fabrication of polysaccharides into hydrogels or microgels can be advantageous for drug-delivery applications. Chemical modification of polysaccharides is usually required before making polysaccharide-based hydrogels or microgels. However, previously described methods usually destroy the chemical structure of polysaccharides and cause degradation. To overcome this challenge, we developed a non-destructive chemical modification method to prepare hydrogels without these disadvantages. This method also introduced a new concept in polysaccharide science. Following our novel chemical modification method, polysaccharide-based hydrogels were made. Compared to the previous polysaccharide hydrogels which usually required long gelation times, our polysaccharide hydrogels gel within seconds with addition of tiny amounts of vinegar. Besides, our polysaccharide-based hydrogels are injectable and spontaneously repair themselves with low toxicity to cells. These properties make our hydrogels promising for cancer-targeted drug delivery. Food is the first necessity of human beings. Pesticides are often used in excessive amounts and in broad distribution, to guarantee high crop productivity. Excess use and/or distribution of pesticides can pollute to the environment and pose threats to human health. To solve this problem, we made all polysaccharide microgels, dispersed in benign water, that can permit slow release of pesticides, applied in a form that can promote great precision. Overall, we developed new ways to modify polysaccharides to create effective and harmless hydrogels or microgels. We aim to push the boundaries of science and benefit human society through our research.

Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2008. / Title from first page of PDF file (viewed July 11, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 67-76).

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論文摘要 本論文由兩篇獨立的文章所構成，第一篇文章從個體角度出發，探討臺灣產業出口與成長之間的關聯性；第二篇文章則以總體的角度，分析世界各主要國家經濟成長的型態(包括出口偏向型的成長與進口偏向型的成長)對該國貿易條件的影響。 長久以來，出口與產出之間的相互影響向來是廣受重視的議題。在國際經濟領域中，多數研究均專注於兩者間理論之建立，關於實證方面的探討並不多見，而個體角度來探討產業出口與成長之間的文獻更是稀少，以臺灣產業出口與成長之間因果關係為對象的研究則付之闕如。臺灣的經濟成就向來被歸功於出口擴張政策的成功，但出口導向的影響範圍究竟擴及多少產業的效果仍不明朗，因此第一篇文章關心的重點，在於探討對我國的產業而言出口擴張是否是個有效的政策？而究竟出口導向和產出導向哪一種政策的效果較好，也是本文所關心的目標。 第二篇文章討論成長型態對貿易條件的影響。由於出口偏向型的成長會使本國願意以更多出口財來換取進口財，將會使本國出口財的國際價格相對下降，進而惡化本國的貿易條件，改善外國的貿易條件；反之，在進口偏向型成長的情況下，出口財的減少則會使本國貿易條件改善，外國貿易條件惡化。是以一國的經濟成長對該國貿易條件的影響，將取決於其生產可能曲線外移的方向。本文嘗試以八個工業化國家和七個開發中國家為對象，在加入成長偏向政策、物價、匯率、所得移轉、對外投資、貿易平衡、貿易開放程度等因素的考慮下，來驗證成長型態對其貿易條件的影響效果是否符合理論的規範。 / The purpose of first paper is to investigate the empirical relationships between exports and domestic production in 22 Taiwan main industries, using time series data for the period 1982:01~2002:07. Different from the previous literatures, this paper examines the relations by taking into account industrial data because we are wondering whether the causal links between exports and outputs still sustain in individual industry, and either export promotion or production-led policies are more effective for industrial production. Hence, three related topics will be discussed: to recognize the incidence of export promotion policy in Taiwan industries, to explore either export promotion or production-led policies is more effective for industrial production, and to detect whether all exportation-oriented industries would simultaneously support export promotion hypothesis. The findings of the econometric analysis employing Granger causality test do not have enough evidence to support that the proportion of exports to production is a necessary condition for generating export promotion. Nevertheless, this study suggests that production makes great influence on exports in Taiwan individual industry but the effects of exports on production is not so prevailing as we thought before. Therefore, the influence of production to exports in Taiwan industry is more prevalent than that of exports to outputs. The purpose of the second paper is to examine the impacts of growth types on terms of trade by making a comparison between 8 industrial countries and 7 developing countries (involving 3 NICs countries). This paper finds that the theories seems not be supported because evidence shows the occurrence of positive effects of export-biased growth to terms of trade are more prevalent than negative ones. Moreover, the empirical results of negative incidence shown by import-biased growth come into conflict with theories, and the impacts of import-biased growth on terms of trade are indefinite. In addition, most results reveals that export-biased growth and import-biased growth policies in industrial countries are invalid, and most results in NICs and developing countries are ambiguous while export-biased growth or import-biased growth policies are adopted. Furthermore, the empirical results reveal that income transferring have great or opposite influence in NICs and developing countries, and trade openness is advantageous to NICs and developing countries but is disadvantageous to developed ones.

Land disposal of solid waste is a vital component of any solid waste management system. Design, operation and closure of municipal solid waste (MSW) landfills are required by regulations to control leachate and gases generated during the life, closure,and post-closure of the facility. Clogging of leachate drainage and removal systems in landfills is a common phenomenon and has been acknowledged in several landfills throughout the United States and abroad. This project was conducted in two phases. Phase I was completed in February of 2005 and Phase II was completed in August of 2006. Leachate characteristics data obtained in Phase I was processed and analyzed, along with supplementary data obtained in Phase II on liquid and solid phase testing. Leachate samples from the landfill and lysimeters indicated the presence of iron and sulfate-reducing bacteria. These bacteria are known to facilitate biologically induced precipitate formation.The mechanism by which biologically ind uced precipitate may form begins with oxidizing acetate by iron and sulfate-reducing bacteria, reducing sulfate to sulfide and ferric iron to ferrous, and then forming calcium carbonate, iron sulfate, and possibly dolomite and other minerals.The results show that the clogging mechanism is driven by two major processes: transformation of volatile acids to substrates by iron and sulfate-reducing bacteria causing local pH and total carbonate to increase, which accelerate calcium carbonate precipitation, and thermodynamically favored reactions in supersaturated conditions based on saturation indices of calcium, sulfide, iron, and other species with respect to minerals. For each 1 mg of consumed volatile acids there were 1.7 mg of calcium, 0.28 mg of sulfate, and 0.03 mg of iron removed. Field and lysimeter precipitate samples were analyzed (using X-Ray Diffraction, Scanning Electron microscopy, and Electron Dispersive Spectroscopy) and correlated with geochemical modeling of leachate const ituents. Precipitate analyses showed the presence of calcium carbonate, brushite (calcium phosphate),and dolomite, where as geochemical modeling showed that calcium carbonate, hydroxyapatite (complex of calcium phosphate), dolomite, pyrite, and siderite may be formed from field and lysimeter leachate constituents. The results also showed that submerged and stagnant conditions in the leachate collction systems accelerate the precipitation process.

En France, il est envisagé de stocker en formation géologique profonde les déchets radioactifs vitrifiés à haute activité et vie longue dans un conteneur en acier inoxydable chemisé par un surconteneur en acier non allié. Les principaux produits de corrosion attendus à la surface de ce dernier, i.e. la sidérite (FeIICO3) et la magnétite (FeIIFeIII2O4), jouent un rôle protecteur contre la corrosion en tant que couche passivante. Ce travail de thèse visait à étudier l’influence des groupes métaboliques bactériens réducteurs du fer ferrique (IRB) et des nitrates (NRB) sur les transformations de ces produits de corrosion en anoxie. Des souches modèles de NRB (Klebsiella mobilis) et IRB (Shewanella putrefaciens) ont, dans un premier temps, été incubées en présence de suspension de sidérite ou de magnétite, afin d’exacerber les processus de transformation du fer du fait d’une surface spécifique élevée, puis dans un second temps, en présence de films électrogénérés de ces produits pour se rapprocher des conditions d’un acier non allié corrodé en anoxie. Ces souches bactériennes sont capables de transformer la sidérite et la magnétite par des processus microbiens directs ou indirects et de conduire à la formation de rouille verte carbonatée (FeII4FeIII2(OH)12CO3). Ce composé occupe une place centrale dans le cycle biogéochimique du fer en anoxie en tant que transitoire commun à plusieurs réactions microbiennes mobilisant le fer sous deux états d’oxydation différents FeII et FeIII. L’originalité de ce travail de thèse est donc de montrer que des métabolismes bactériens inaccoutumés tels que les NRB ou les IRB sont susceptibles de jouer un rôle dans les processus de biocorrosion / Radioactive waste is one of the major problems facing the nuclear industry. To circumvent this issue France plans to store vitrified high-level nuclear waste in a stainless steel container, placed into a non-alloy steel overpack, at a depth of 500m in an argillaceous formation. The main iron corrosion products formed at the surface of the non-alloy steel are siderite (FeIICO3) and magnetite (FeIIFeIII2O4). These compounds are formed in the anoxic conditions present in the nuclear waste repository and play a protective role against corrosion as a passive layer. This work aims to investigate the activity of nitrate-reducing bacteria (NRB, Klebsiella mobilis) and iron-reducing bacteria (IRB, Shewanella putrefaciens) during the transformation of siderite and magnetite, especially those involved in anoxic iron biogeochemical cycle. Klebsiella mobilis and Shewanella putrefaciens were first incubated with siderite or magnetite suspensions (high surface specific area) in order to exacerbate the microbial iron transformation, subsequently incubated with a magnetite/siderite film synthesized by anodic polarization at applied current density. The transformation of siderite and magnetite by direct or indirect microbial processes led to the formation of carbonated green rust (FeII4FeIII2(OH)12CO3). As a transient phase shared by several bacterial reactions involving FeII and FeIII, this compound is the cornerstone of the anoxic iron biogeochemical cycle. The novelty of this thesis is the consideration of bacterial metabolisms of NRB and IRB often overlooked in biocorrosion processes