In this study, potassium permanganate was used as the oxidant to remediate TCE¡Vcontaminated groundwater. The objectives of this bench-scale oxidation study include the following: (1) evaluate the overall TCE oxidation rate with the presence of KMnO4, (2) assess the consumption rate of KMnO4, (3) evaluate the effect of the oxidation by-product, manganese dioxide (MnO2), on the TCE oxidation rate. The control factors in this study include (1) four different molar ratios of KMnO4 to TCE [designated as P, (KMnO4/TCE) = 2, 5, 10, and 20]; (2) four different TCE concentration (0.5, 5, 20, and 100 ppm); (3) three different initial pH values (2.1, 6.3, and 12.5); (4) three different oscillator mix rate (0, 50, and 200 rpm); (5) four different molar ratios of dibasic sodium phosphate (Na2HPO4) to Mn2+ [designated as D, (Na2HPO4/Mn2+) = 0, 50, 100, and 300D], and (6) two different medium solutions [deionized (DI) water and groundwater]. Moreover, the effects of D values on TCE oxidation rate and KMnO4 consumption rate were also evaluated. Experimental results indicate that a second-order reaction model could be applied to express the oxidation reaction of TCE by KMnO4, and the calculated rate constant equals 0.8 M-1s-1. Results also show that the higher the P value, the higher the TCE oxidation rate. Moreover, TCE oxidation rate was not affected under low pH conditions (pH = 2.10 and 6.3). However, TCE oxidation rate dropped under high pH condition (pH 12.5) due to the transformation of KMnO4 to manganese dioxide. The following three pathways would cause the production of manganese dioxide: (1) direct oxidation of TCE by KMnO4, (2) production of Mn2+ after the oxidation of TCE by KMnO4, and Mn2+ was further oxidized by KMnO4 to form manganese dioxide, and (3) transformation of KMnO4 to manganese dioxide under high pH condition. Results also show that more manganese dioxide was produced while groundwater was used as the medium solution. Results show that the produced manganese dioxide was 47.2% - 81.5% less with the addition of dibasic sodium phosphate. Moreover, the variations in D values would not affect the TCE oxidation rate. However, the increase in D value would decrease the consumption of KMnO4. Results also reveal that significant inhibition of manganese dioxide production was observed under low pH condition. Furthermore, no TCE oxidation byproducts were detected after the oxidation reaction. Key words: KMnO4, TCE, manganese dioxide and dibasic sodium phosphate

Nitrogen oxide in water was a critical factor of eutrophication. The poor tap-water quality in Taiwan was the result of ammonia nitrogen pollution. This research used manganese dioxide as the catalyst to degrade ammonia nitrogen content in water. Controlled factors in our experiment include basic test, optimal reaction condition test, and kinetics. Real water sample was drawn from the Love River for catalysis effect test. Results were then compared with the popularly used titanium dioxide. Significant findings in this research include: 1) when the manganese dioxide content in water was 2%, the ammonia nitrogen removal rates were 31.80% under UV irradiation, and 22.21 % without light interference; 2) under UV irradiation, manganese dioxide would not affect the catalysis effect due to pH changes; 3) silicate in the water had catalysis effect, while sulfate, phosphate, and nitrate had inhibition effect; 4) manganese dioxide had catalysis effect in seawater, yet the removal rate would decrease as the salt content increases; 5) the rise of water temperature would enhance the ammonia nitrogen removal rate; 6) manganese dioxide had catalysis effect on the treatment of the Love River water, and the ammonia nitrogen removal rate reached 89.50 %; 7) in the biological test, manganese dioxide could effectively degrade the ammonia nitrogen content in water, and improve the survival rate of larval shrimp; 8) comparing to titanium dioxide, manganese dioxide had advantages of low cost, with catalysis effect in both seawater and fresh water under no light condition. As a result, manganese dioxide has significant future application potentials. In the future, this research will conduct in-depth study on kinetics of degradability of manganese dioxide catalysis on ammonia nitrogen, and to design suitable catalytic reactor for water treatment. Moreover, it is of value to broadly research manganese dioxide related catalytic products, such as catalytic spray, catalytic paint, fluorescent tube, air filter, and catalytic fan...etc.

M. Tech. Department of Chemical, Metallurgical and Materials Engineering. / Discusses how to synthesize a titanium-manganese oxide composite electrode with improved supercapacitive properties. The research aim was achieved through the following objectives: 1. the mechanisms of the synergistic incorporation of manganese oxide for improving the supercapacitive properties of titanium oxide electrodes. 2. Investigate possible metallurgical interactions and phenomenon during the sintering of the composite. 3. Investigate the electrochemical characteristics of titanium-manganese composite electrodes.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Glucocorticoids are exploited for the treatment of hematological malignancies due to their ability to cause apoptosis in lymphoid cells. Innate and acquired resistance, however, limits their efficacy in the clinic. The mechanisms contributing to resistance are poorly understood. A better understanding of the critical events during glucocorticoid-induced apoptosis are needed in order to develop novel agents that will exploit these critical targets and improve the response to glucocorticoid-based therapies. Previously, using WEHI7.2 murine thymic lymphoma cells, our laboratory demonstrated that the levels of reactive oxygen species (ROS) increase during glucocorticoid-induced apoptosis signaling. WEHI7.2 cell variants with increased catalase exhibit increased resistance to glucocorticoids, suggesting that oxidative stress plays a role in glucocorticoid-induced apoptosis and that increasing the intracellular production of ROS may be a potential strategy for sensitizing lymphoma cells to glucocorticoid treatment. The following studies demonstrate that an increase in H₂O₂ is essential for lymphoma cells to undergo apoptosis and that the ability to remove cellular H₂O₂ protects the cells from glucocorticoid-mediated cell death. The redox-cycling agent, Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl) porphyrin, increased glucocorticoid-induced oxidative stress in WEHI7.2 cells and sensitized the cells to glucocorticoid treatment. MnTE-2-PyP⁵⁺ glutathionylated NF-κB and inhibited its activity. Collectively, these findings suggest that manipulating the redox environment with MnTE-2-PyP⁵⁺ is a promising approach for lymphoma therapy.

Experiments were conducted with littermate gilts maintained in stainless steel metabolism cages within environmentally controlled rooms and consuming a corn-soybean meal based diet. The objectives of these studies were to investigate the impact of different dietary levels of manganese (Mn) and/or stage of the reproductive cycle on mineral metabolism and more specifically Mn metabolism in primigravid gilts and rats. Nutritional status was assessed using conventional balance studies, the analyses of physiological fluids (urine, plasma, colostrum, milk), tissues of the dam and offspring, and by a radioisotope dilution-balance technique. Trace element retention in the first-litter gilt was not significantly altered by dietary Mn restriction (11 $ mu$g/g DM) or by different stages of the reproductive cycle. In contrast, among the macro elements, phosphorus and perhaps calcium retention were improved in late gestation, whereas magnesium and nitrogen retention were unchanged. The weight of the litter at birth from dams consuming the low Mn (LMn) diet was significantly less than high Mn (HMn) gilts (96 $ mu$g/g DM). The Mn concentration in the liver and kidney of HMn gilts were significantly higher than in LMn gilts at the end of lactation. Likewise, the bones from HMn piglets contained higher concentrations of Mn at birth, and the liver and kidney concentrations were greater at weaning. Dietary Mn intake did not influence the rate of $ sp{54}$Mn excretion by the gilt during late gestation. The endogenous fecal Mn component was of similar magnitude, averaging 0.26 and 0.21 mg/d for the HMn and LMn gilts, respectively. However, the endogenous contribution to total fecal Mn was almost 8 fold different, representing 0.12% and 0.82% of total fecal Mn for the HMn and LMn gilts, respectively. The biological half-life of Mn in the body of the gilt was not influenced by dietary Mn within the intake range of 26 to 210 mg/d and averaged 54 days. The turnover rate (TR) of Mn was es

Magnesium sheet for automotive applications is very attractive due to its light weight. The poor formability of magnesium and its alloys at room temperature, however, has limited the applications of these alloys. For this reason, at present, magnesium must be formed at elevated temperatures. This study investigates the hot deformation and fracture characteristics of Mg-1wt% Zn alloys containing a range of Al and Mn levels. Hot-rolled specimens were tensile tested over a range of strain rates and temperatures. Strain rate versus flow stress diagrams plotted on log-log scales revealed a transition in deformation mechanisms as a change in slope (the 'stress exponent'). Specifically, non-uniform deformation (i.e. necking) is observed at high strain rates, while uniform deformation is observed at low rates. This transition is accompanied by a change in fracture mechanism from dimpled rupture at high strain rates to cavitation and cavity interlinkage at low strain rates. Specimens which had a stress exponent of ∼2 and which failed through uniform deformation showing interlinked cavities have been associated with the grain boundary sliding (GBS) deformation mechanism. Specimens which had a stress exponent of ~5 and which failed through necking showing a dimpled fracture surface have been associated with the dislocation creep deformation mechanism. Increasing aluminum appears to somewhat favour the GBS regime as indicated by a slightly decreasing stress exponent. Manganese also appears to favor the GBS regime, since the onset of cavitation appears at higher strain rates compared to alloys without Mn.

No description available.

Productivity in large areas of the world's oceans is limited by low concentrations of dissolved iron in surface waters. Phytoplankton have adapted to persist in these environments by reducing their requirements for iron (Fe) in key metabolic pathways, in some cases by replacing Fe-containing catalysts with their iron-free functional equivalents. This thesis examines the requirements and biochemical roles for copper (Cu) and manganese (Mn) in Fe-limited centric marine diatoms. A major finding of my research is that diatoms have elevated requirements for Mn and Cu when grown in Fe-deficient seawater. Iron deficiency induces oxidative stress and increases the cellular concentrations of toxic oxygen radicals and damage products in Thalassiosira pseudonana. The increased Mn-requirement is used, in part, to activate Mn-containing isoforms of the antioxidant enzyme superoxide dismutase. Cultures co-limited by Fe and Mn exhibit high levels of oxidative stress and an inefficient detoxification pathway that further reduces cell growth. Diatoms isolated from the metal poor open ocean require more Cu to divide than related species from metal-rich coastal waters. This pattern is in stark contrast to all other known nutritive trace metals. One part of the diatom Cu requirement that is independent of provenance is for efficient Fe transport. The additional Cu requirement of oceanic species appears to be due to the constitutive expression of a Cu-containing electron transport protein, possibly plastocyanin. Coastal species, which have higher Fe-requirements for growth, retain the Fe-containing functional homologue cytochrome c6. By employing metals other than Fe within photosynthesis and antioxidant pathways, marine diatoms are able to increase their fitness in Fe-deficient environments. However, Mn and Cu also occur in low concentrations in the open ocean and thus may co-limit growth of natural populations of phytoplankton. Metal enrichment experiments i

The synthesis, structure, and reactivity of some organometallic-fusedheterocycles were studied. This work was divided into three parts: first,thiapentalenyl tricarbonyl manganese complexes [Mn(CO)3{??5-SC7H3-1,3-(R)2}]were synthesized employing thiation on diacyl precursors; second, attempts toform the 5,5-fused ring pyrrole analogs to the thiapentalenyl complexes led to theformation of various amine and imine ligands and manganese complexes, but notthe desired ring-closed pyrroles; third, reductive amination on a ferrocenylmonoaldehyde substrate led to the formation of di(N-(ferrocenylmethyl))-Nmethylamineand its cyanoborane and cyanoborohydride analogs.Isolation of the desired thiapentalenyl manganese complexes wasaccomplished by first forming 1,2-diacylcyclopentadienes (fulvenes), convertingto the corresponding thallium salts [Tl{1,2-C5H3(COR)2}] employing thalliumethoxide, transmetallating with [Mn(CO)5Br], and ring closing using either P4S10or Lawesson's Reagent. Ring closure from the diacylmanganese complexes[Mn(CO)3{??5-1,2-C5H3(COR)2}] gave air stable thiapentalenyl complexes inmoderate to good yield and was tolerable to a variety of functional groups (aryl,arylacetyl, t-butyl). In the cases where 1,2-diarylacetyl complexes wereemployed, the isolated products were "quinoidal". While ring closure on thecorresponding diacylrhenium tricarbonyl complexes was not feasible, it wasobserved that these quinoidal thiapentalenyl structures could be formed on aruthenium Cp* moiety using the arylacetyl fulvenes.Various keto-amines or enol-imines could be formed from the 1,2-dibenzoyl fulvene employing primary amines (R = H, Me, OH, OMe). In thepresence of a reducing agent, neither reduction nor ring closure was observedfor any of the cases investigated. Formation of the corresponding manganesetricarbonyl complex for the methyoxyimine case was accomplished by reaction ofthe enol-methoxyimine with thallium ethoxide and then transmetallating with[Mn(CO)5Br]. Reaction of this keto-imine complex with various reducing agentsdid not lead to the desired 5,5-fused ring pyrrole complex but to reduction to thecorresponding alcohol.Diferrocenylmethyl methylamine complexes were obtained by reaction offerrocene monoaldehyde with ferrocenylmethyl methylamine in the presence of amild reducing agent (NaCNBH3). Isolation under anhydrous conditions gave theunexpected cyanoborohydride salt, di(N-(ferrocenylmethyl))-N-methylammoniumcyanoborohydride. Aqueous work-up gave the corresponding free amine.Conversion of the cyanoborohydride salt to the corresponding cyanoborane,di(N-(ferrocenylmethyl))-N-methylammonium–cyanoborane, was accomplishedby refluxing the cyanoborohydride salt in THF.