251 |
Fenton-like Reaction of As(III) in a Simulated Subsurface Environment via Injection of Nanoiron Slurry Combined with the Electrokinetic ProcessChen, Tsu-Chi 25 August 2010 (has links)
Abstract
The object of this study was to investigate the synthesis of a nanoscale zero-valent iron slurry (NZVIS) for use in Fenton-like reactions, and to evaluate its efficiency for As(III) oxidation to As(V) in spiked deionized water and simulated groundwater containing humic acid. Furthermore, this study used injection of the nanoiron slurry combined with electrokinetic processes to remediate As(III) in soil.
NZVI was prepared by a chemical reduction process. The efficiency of using 3 wt% soluble starch (SS) to stabilize NZVI was also studied. It was found that the SS could keep the nanoparticles dispersed for over one day. The NZVI was characterized by XRD, FE-SEM, ESEM-EDS, and EDS-mapping, to observe its morphology and crystal structure. In this research the iron species observed took non-crystalline forms.
In water batch tests, studies in deionized water were compared with those in simulated groundwater with humic acid, and dissolved oxygen content was adjusted. Injection of NZVIS oxidized As(III) to As(V) in all cases. In both deionized water and simulated groundwater, it was found that when the dissolved oxygen(DO) content was not increased, the NZVIS generated non-selective oxidant OH¡E, thus reducing the As(V) production rate. When dissolved oxygen content was increased, the DO oxidized organic matter present in the simulated groundwater, allowing the OH¡E to react further with As(III) and increasing the As(V) production rate. Finally, a test was performed in actual groundwater under optimal reaction conditions, without increasing the dissolved oxygen content, for comparison of As(V) yield. The concentration of As(V) was found to be higher in this test (As(V) Conc. = 17.55 £gg/L) than when using simulated groundwater (As(V) Conc. = 4.63 £gg/L).
This study further examined NZVIS injection combined with electrokinetic (EK) technology for the remediation of soil columns containing a low concentration (initial conc. = 100 mg/kg) and a high concentration (initial conc. = 500 mg/kg) of As(III). EK alone without injection of NZVIS (Test E-1) resulted in a residual soil As(V) concentration of 24 mg/kg in the low-concentration test group. In Test E-2, where NZVIS was injected into the anode reservoir, and Test E-3, where NZVIS was injected into the cathode reservoir, residual soil As(V) concentrations were 2.3 mg/kg and 3.4 mg/kg, respectively.
The high-concentration test group was comprised of Test E-4 (EK alone without injection of NZVIS), Test E-5 (NZVIS injected into anode reservoir), and Test E-6 (NZVIS injected into cathode reservoir). In these tests, only soil sections 0.2 and 0.4 (normalized distance from anode reservoir) met soil regulation standards. Residual As(V) concentrations in soil sections 0.6, 0.8, and 1.0 are much higher than the regulatory standard. In soil section 1.0, the residual As(V) concentration was less in Test E-6 than in Test E-5 (116.6 mg/kg and 183.5 mg/kg, respectively). This may be because at high pH values, the iron surface does not corrode, instead arsenic adsorption prevails. Only a fraction of negatively charged As(V) species will migrate towards the anode resulting in a relatively low soil As(V) concentration near the cathode.
|
252 |
A nalyzing Fair Water rate of Taiwan Water CorporationWeng, Yen-sheng 16 August 2006 (has links)
Abstract
Engineering, service and finance are three main tasks of Taiwan Water Corporation. Water rate is not only the main factor which determines the financial income, but also the significant managerial means which influence the efficiency of water resources allocation.
Current water rate of Taiwan Water Corporation hasn¡¦t been adjusted for at least twelve years. During these years, price index raises and people are getting more and more demanding for water quality and stability of water supply. On the other hand, it costs increasingly to develop new water resources and increase the popularity rate, not to mention about replacing pipes and improving water quality. These entire efforts make operation cost rise enormously year by year.
Because the water rate can¡¦t reflect its cost for so many years, Taiwan Water Corporation has been long term in debt. This affects not only the general operation. Meanwhile, Taiwan Water Corporation also has no finance to develop water resources and improve water supply system. So it is really critical that water rate should be adjusted right away to reflect the cost of water supply reasonably. It will help a lot to improve the operation of Taiwan Water Corporation and then it can continuously provide high quality of service.
This study investigates (1) current operations of Taiwan Water Corporation (2) reasonable water rate structure and calculation (3) mechanism of water rate adjustment (4) proposal of exercising the income of the increase of water rates (5) complete sets of water rate adjustment.
This study suggests that water rate should be reviewed once a year. Through this procedure, Taiwan Water Corporation would build up a reasonable water rate adjustment mechanism. Then we expect that it will improve the finance of Taiwan Water Corporation. Also by raising the water rate, people would start to realize that water is valuable and limited resources and promote to achieve the goal to utilize water resources efficiently.
Key words¡GAverage ¡V Cost Pricing¡AMarginal ¡V Cost Pricing¡Aand Investment
Return Rate
|
253 |
The sorption of uranium(VI) and neptunium(V) onto surfaces of selected metal oxides and alumosilicates studied by in situ vibrational spectroscopyMüller, K. 22 September 2010 (has links) (PDF)
The migration behavior of actinides and other radioactive contaminants in the environment is controlled by prominent molecular phenomena such as hydrolysis and complexation reactions in aqueous solutions as well as the diffusion and sorption onto minerals present along groundwater flow paths. These reactions significantly influence the mobility and bioavailability of the metal ions in the environment, in particular at liquid-solid interfaces.
Hence, for the assessment of migration processes the knowledge of the mechanisms occurring at interfaces is crucial. The required structural information can be obtained using various spectroscopic techniques.
In the present study, the speciation of uranium(VI) and neptunium(V) at environmentally relevant mineral – water interfaces of oxides of titania, alumina, silica, zinc, and alumosilicates has been investigated by the application of attenuated total reflection Fouriertransform infrared (ATR FT-IR) spectroscopy. Moreover, the distribution of the hydrolysis products in micromolar aqueous solutions of U(VI) and Np(V/VI) at ambient atmosphere has been characterized for the first time, by a combination of ATR FT-IR spectroscopy, near infrared (NIR) absorption spectroscopy, and speciation modeling applying updated thermodynamic databases.
From the infrared spectra, a significant change of the U(VI) speciation is derived upon lowering the U(VI) concentration from the milli- to the micromolar range, strongly suggesting the dominance of monomeric U(VI) hydrolysis products in the micromolar solutions. In contradiction to the predicted speciation, monomeric hydroxo species are already present at pH ≥ 2.5 and become dominant at pH 3. At higher pH levels (> 6), a complex speciation is evidenced including carbonate containing complexes.
For the first time, spectroscopic results of Np(VI) hydrolysis reactions are provided in the submillimolar concentration range and at pH values up to 5.3, and they are comparatively discussed with U(VI). For both actinides, the formation of similar species is suggested at pH ≤ 4, whereas at higher pH, the infrared spectra evidence structurally different species. At pH 5, the formation of a carbonate-containing dimeric complex, that is (NpO2)2CO3(OH)3^-, is strongly suggested, whereas carbonate complexation occurs only under more alkaline conditions in the U(VI) system.
The results from the experiments of the sorption processes clearly demonstrate the formation of stable U(VI) surface complexes at all investigated mineral phases. This includes several metal oxides, namely TiO2, Al2O3, and SiO2, serving as model systems for the elucidation of more complex mineral systems, and several alumosilicates, such as kaolinite, muscovite and biotite. From a multiplicity of in situ experiments, the impact of sorbent characteristics and variations in the aqueous U(VI) system on the sorption processes was considered.
A preferential formation of an inner-sphere complex is derived from the spectra of the TiO2 and SiO2 phases. In addition, since the in situ FT-IR experiments provide an online monitoring of the absorption changes of the sorption processes, the course of the formation of the U(VI) surface complexes can be observed spectroscopically. It is shown that after prolonged sorption time on TiO2, resulting in a highly covered surface, outer-sphere complexation predominates the sorption processes. The prevailing crystallographic modification, namely anatase and rutile, does not significantly contribute to the spectra, whereas surface specific parameters, e.g. surface area or porosity are important.
A significant different surface complexation is observed for Al2O3. The formation of innerspheric species is assumed at low U(VI) surface coverage which is fostered at low pH, high ionic strength and short contact times. At proceeded sorption the surface complexation changes. From the spectra, an outer-spheric coordination followed by surface precipitation or polymerization is deduced. Moreover, in contrast to TiO2, the appearance of ternary U(VI) carbonate complexes on the γ-Al2O3 surface is suggested.
The first results of the surface reactions on more complex, naturally occurring minerals (kaolinite, muscovite and biotite) show the formation of U(VI) inner-sphere sorption complexes. These findings are supported by the spectral information of the metal oxide surfaces.
In this work, first spectroscopic results from sorption of aqueous Np(V) on solid mineral phases are provided. It is shown that stable inner-sphere surface species of NpO2 ^+ are formed on TiO2. Outer-sphere complexation is found to play a minor role due to the pH independence of the sorption species throughout the pH range 4 – 7.6. The comparative spectroscopic experiments of Np(V) sorption onto TiO2, SiO2, and ZnO indicate structurally similar bidentate surface complexes.
The multiplicity of IR spectroscopic experiments carried out within this study yields a profound collection of spectroscopic data which will be used as references for future investigations of more complex sorption systems in aqueous solution. Furthermore, from a methodological point of view, this study comprehensively extends the application of ATR FT-IR spectroscopic experiments to a wide range in the field of radioecology.
The results obtained in this work contribute to a better understanding of the geochemical interactions of actinides, in particular U(VI) and Np(V/VI), in the environment. Consequently, more reliable predictions of actinides migration which are essential for the safety assessment of nuclear waste repositories can be performed.
|
254 |
Machtkonsolidierung unter V. V. Putin : eine Analyse im Lichte europäischen und russischen Rechtsstaatsdenkens /Taubert, Denis. January 2009 (has links) (PDF)
@St. Gallen, Univ., Diss., 2009.
|
255 |
Prievartos variantai šiuolaikinėje lietuvių poezijoje (G. Patackas ir V. Gedgaudas) / Variants of violence in modern lithuanian poetry (G. Patackas and V. Gedgaudas)Butkutė, Evelina 25 September 2008 (has links)
Literatūros sociologai teigia, jog lietuvių poezijai praėjusio amžiaus IX – X dešimtmečiai itin reikšmingi, nes tuo laikotarpiu gimė nauja kūrėjo laikysena – poetai aplinką ėmė vaizduoti šaltą ir atstumiančią, į poeziją įtraukiamas visuomenėje plintančio reiškinio – prievartos – vaizdinys. Poezija kito kartu su politiniais, ekonominiais ir socialiniais pokyčiais valstybėje. Minėtam laikotarpiui būdingus eilėraščius kūrė dviejų kartų poetai.
Šio darbo objektas – G. Patacko eilėraščių rinktinė „Jazmino žiedas vakarą prakalbina“ bei V. Gedgaudo poezijos rinkiniai „Vakaras be žiburio“ ir „Kapsulė“. Poetų kūryba pasirinkta neatsitiktinai – jie panašūs savo pasaulėžiūra, kurią galima pavadinti prometėjiška. G. Patackas ir V. Gedgaudas atmeta klasikinį grožio supratimą, pasitelkdami prievartos ir brutalumo metaforas griauna poezijoje nusistovėjusias normas, nes tai – reiškiniai, atspindintys šiuolaikinį pasaulį. Magistrinio darbo tikslas – pasitelkiant literatūros sociologijai rūpimus klausimus, aptariant literatūrinį poetų kūrybos lauką panagrinėti kodėl ir kokiu būdu G. Patackas ir V. Gedgaudas savo kūryboje plačiai vartoja prievartos variantus, kokias prasmes šie variantai įgauna lyrikoje. Fundamentali prievartos ar smurto reikšmė – jėgos vartojimas, vertimas ką daryti, žala žmonėms juos žudant, luošinant ar sužeidžiant. Mokslininkai išskiria kelias prievartos rūšis, magistriniame darbe jos vadinamos variantais, pagrindinės jų – fizinė ir psichologinė. Šiuos... [toliau žr. visą tekstą] / The sociologists of Lithuanian literature say that IX and X decades of the last century are very important to Lithuanian poetry as then the new author’s attitude was born – poets began representing cold and repulsive surroundings in their creations. They included the images of violence which became the everyday occurrence in our society of that time. Poetry was changing together with political, economical and social life in our state. Two poets of those generations wrote poems which have characteristics of that particular period.
The object of the presented work is G. Patackas’ selection of poems “Jazmino žiedas vakarą prakalbina” („The Jasmine Blossom is Making an Approach to the Evening“) and two collections of poems by V. Gedgaudas – “Vakaras be žiburio” (“An Evening without the Light”) and “Kapsulė” (“The Capsule”). These poets were chosen not accidentally – they are similar in their poetry by their outlook on the world, which could be called “prometheism”. G. Patackas and V. Gedgaudas reject the classical conception of beauty, they are destroying the standards of the poetry. Poets invoke metaphors of violence and brutality as these phenomena reflect the modern world. The purpose of this master’s work is to try to ascertain why G. Patackas and V. Gedgaudas use variants of violence in their creation, how they do that and what are the meanings of these variants in their poetry. The presented work is based on the literature’s sociology. The fundamental meaning of... [to full text]
|
256 |
Avfallsfraktioner i Sveriges hamnar / Garbage fractions in Swedish portsLjungqvist, Helena, Lönnqvist, Jonas January 2015 (has links)
Varje år ökar avfallsmängden och användningen av naturens resurser vilket gör att återvinning blir en viktig del för ett hållbart samhälle. Årligen dumpas mer än 6,4 miljoner ton plast i haven från fartyg. Den 1 januari 2013 skärptes regelverket MARPOL för att minska mängden avfall som slängs i havet. Mot denna bakgrund har syftet med studien varit att undersöka hur motivationen att sortera kan påverkas av antalet avfallsfraktioner i hamnarna. En kvalitativ metod med sju intervjuer har använts. Resultatet visar att antalet fraktioner inte är det viktigaste för att öka återvinningen. Studien visar också att det saknas en standard i hamnarna. Tillgänglighet, närhet och att det är enkelt att lämna avfallet framkommer som de viktigaste faktorerna. / Every year the amount of garbage and the use of natural resources increases which makes recycling an important subject for a sustainable society. Yearly more than 6,4 million tons of plastic is dumped into the oceans from ships. From the 1st of January 2013 MARPOL regulation got stricter to decrease the discharge of garbage into the sea. Against this background the purpose of this study has been to examine how the motivation to recycle can be effected of the number of garbage fractions in the ports. A qualitative method has been used and seven interviews were conducted. The result shows that the number of fractions is not the most important factor to increase recycling. The study also shows that there is no standard in the ports. Accessibility, proximity and that it is easy to carry out emerges as the main factors.
|
257 |
DISSECTING THE BIOSYNTHESES OF GILVOCARCINS AND RAVIDOMYCINSKharel, Madan Kumar 01 January 2010 (has links)
Gilvocarcin V (GV) and ravidomycin (RMV) exhibit excellent antitumor activities in the presence of near-UV light at low concentration maintaining a low in vivo cytotoxicity. Although, the exact molecular mechanism for in vivo actions of these antibiotics has yet to be determined, a [2+2] cycloaddition reaction of the vinyl side chain with DNA thymidine residues in addition to the inhibition of topoisomerase II and DNAhistone H3 cross-linking are reported for the GV’s mechanism of action. Such activities have made these molecules interesting candidates for the biosynthetic investigation to generate analogues with improved activity/solubility. Previous biosynthetic studies have suggested that the GV biosynthetic pathway involves a number of synchronously occurring transformations leading to the oxidative C-C bond cleavage and other intriguing biosynthetic reactions, such as the vinyl side chain formation, methylations, Cglycosylation and dehydrogenation. Although gene inactivation results identified many candidate genes whose corresponding enzymes are involved in these biochemical transformations, their exact functional roles and the identity of their natural substrates remained elusive. To provide more insights into these complex biochemical tranfrormations, three specific aims were set up.
Specific aim 1 was to clone and characterize the RMV biosynthetic gene cluster. Through the comparison of GV cluster with the RMV cluster, the genes encoding the biosynthesis of sugar and tetracyclic aromatic moieties were identified. RavGT, the sole glycosyltransferase of the RMV cluster has demonstrated to have unprecedented sugar donor substrate flexibility, transferring an amino-pyranose sugar as well as a neutral furanose sugar.
Specific aim 2 was to characterize all of the TDP-D-ravidosamine biosynthetic enzymes. The aim also included to a one-pot enzymatic synthetic protocol for the routine production of TDP-D-ravidosamine.
Specific aim 3 focussed on a total enzymatic synthesis of defucogilvocarcin M (defucoGM), the polyketide-derived core of GV and RMV. This aim clearly identified the minimal enzymes required to biosynthesize the complex architecture of defucoGM from the simple building blocks acetate and malonate. In addition, the GV-pathway enzyme GilR was fully characterized. Through in vitro studies, GilR was shown to catalyze the dehydrogenation of hemiacetal moiety of the penultimate intermediate pregilvocarcin V to the lactone moiety of GV at the last step.
|
258 |
COMBINATORIAL BIOSYNTHETIC DERIVATIZATION OF THE ANTITUMORAL AGENT GILVOCARCIN VShepherd, Micah Douglas 01 January 2011 (has links)
Gilvocarcin V (GV), the principal product of Streptomyces griseoflavus Gö 3592 and other Streptomyces spp., is the most prominent member of a distinct class of antitumor antibiotics that share a polyketide derived coumarin-based aromatic core. GV and other members of this class including polycarcin V from Streptomyces polyformus, often referred to as gilvocarcin-like aryl C-glycosides, are particularly interesting because of their potent bactericidal, virucidal and antitumor activities at low concentrations while maintaining low in vivo toxicity. Although the precise molecular mechanism of GV bioactivity is unknown, gilvocarcin V has been shown to undergo a photoactivated [2+2] cycloaddition of its vinyl side chain with thymine residues of DNA in near-UV or visible blue light. In addition, GV was shown to selectively crosslink histone H3 with DNA, thereby effectively disrupting normal cellular processes such as transcription. Furthermore, GVs ability to inhibit topoisomerase II has also been attributed as a mechanism of action for gilvocarcin V activity. The excellent antitumor activity, as well as an unprecedented structural architecture, has made GV an ideal candidate for biosynthetic studies toward the development of novel analogues with improved pharmacological properties. Previous biosynthetic research has identified several candidate genes responsible for key steps during the biosynthesis of gilvocarcin V including an oxygenase cascade leading to C-C bond cleavage, methylations, lactone formation, C-glycosylation and vinyl side chain formation.
In this study, we further examined two critical biosynthetic transformations essential for the bioactivity of gilvocarcin V, namely starter unit incorporation and C-glycosylation, through the following specific aims: 1) creation of functional chimeric C-glycosyltransferases through domain swapping of gilvocarcin-like glycosyltransferases and identification and evaluation of the donor substrate flexibility of PlcGT, the polycarcin V pathway specific C-glycosyltransferase; 2) creation of a library of O-methylated-L-rhamnose analogues of polycarcin V for structure activity relationship studies; 3) identification of the role of GilP and GilQ in starter unit specificity during gilvocarcin V biosynthesis; and 4) creation of a plasmid based approach in which selective gilvocarcin biosynthetic genes were utilized to produce important gilvocarcin intermediates for further in vivo and in vitro experimentation.
|
259 |
Nouvelle approche de formulation des bétons drainants aux propriétés mécaniques et drainantes amélioréesKabagire Kibenga, Daddy January 2013 (has links)
Le béton drainant est généralement utilisé pour ses caractéristiques drainantes, d'ailleurs ces dernières décennies ont été marqué par une utilisation croissante du béton drainant aux États-Unis, à cause de l'adoption d'une loi spéciale sur la gestion des eaux de ruissèlement et de surface. Les applications les plus courantes sont: les aires de stationnements, les chaussées à faible trafic et les terrains de tennis. Cependant, le béton drainant possède des faibles propriétés mécaniques comparativement au béton conventionnel. Ceci est dû à sa porosité effective relativement importante. Le but principal pour le concepteur est alors de trouver un équilibre entre les propriétés mécaniques et drainantes conformément aux exigences voulues. Dans cette étude, un intérêt particulier est porté sur la méthode de formulation du béton drainant. La méthode proposée dans la littérature ne couvre pas tous les granulats et ne fournit pas de recommandations simples d'application pour faciliter la procédure de formulation. Dans la méthode proposée, la porosité inter-granulaire, déterminée via la compacité granulaire, est le paramètre principal pour la formulation des bétons drainant. Il est également question d'évaluer l'effet de différents paramètres de formulation ainsi que de l'effet de l'énergie de consolidation sur les propriétés drainantes et mécaniques des bétons drainants. Les échantillons de béton sont préparés en utilisant deux différents niveaux d'énergie de consolidation. Une modélisation à l'aide des plans d'expériences considérant trois paramètres les plus influents (Rapport E/C, le volume de pâte, et la teneur en agent réducteur d'eau) a permis de quantifier la contribution de chaque paramètres ainsi que leur interactions sur les différentes propriétés évaluées. Afin de faciliter l'approche de formulation des bétons drainants, le volume de pâte est exprimé en fonction du volume de vide inter-granulaire (V P /VVG ). L'effet des particules fines sur les propriétés mécaniques a également été évalué. Les résultats 'de cette étude montrent que les propriétés déterminées à partir de la courbe granulométrique ne suffisent pas pour prédire la porosité inter-granulaire des granulats utilisés. Les résultats ont également montré que la formulation des bétons drainants est réalisable avec des rapports V P /GVG compris entre 30 à 60%. Cependant, le rapport VP /VVG optimal trouvé est situé à environ 50%. Par ailleurs, les résultats montrent que les propriétés mécaniques ne dépendent pas de la taille des granulats, mais elles sont fonction de la distribution granulométriques et de la quantité des éléments fins des granulats. L'analyse des résultats obtenus sur les bétons étudiés dans le programme montre que la porosité requise pour obtenir une perméabilité minimale de 1 mm/sec est de 19%. Les modèles statistiques établis sont fiables et peuvent être utilisé pour décrire l'influence des paramètres étudiés (rapport E/C, VP /VVG , agent réducteur d'eau) sur les propriétés drainantes et mécaniques du béton drainant. La validation des modèles est réalisée à l'aide des points centraux et des mélanges de la première phase se trouvant dans le domaine expérimental. Ces modèles sont exploités pour tracer les iso-réponses qui peuvent servir de guide de sélection de matériau pour faciliter la formulation des bétons drainants. Les modèles statistiques montrent que le rapport V P /VVG est le paramètre le plus influent parmi les paramètres étudiés. D'autre part, il est observé que le rapport E/C a une influence significative sur les propriétés mécaniques, En effet, une augmentation du rapport E/C améliore les propriétés mécaniques. [symboles non conformes]
|
260 |
The Politics of Protection: The Forgotten History of Georgia Feminists and Doe v. BoltonMcGee, Alexandra 11 August 2015 (has links)
In this thesis, I will argue that Doe v. Bolton, 410 U.S. 179 (1973), a United States Supreme Court case originating in Georgia, enabled all women access to abortion, including groups of marginalized women previously denied this right. An examination of the background of Doe uncovers the roles played by Georgia feminists and the medical community. By comparing Doe v. Bolton with the concurrent Supreme Court case of Roe v. Wade, I will shed light on the history of abortion in America as well as continuing divisions over abortion access in America today.
|
Page generated in 0.0337 seconds