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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

Mediator combined gaseous substrate for electricity generation in microbial fuel cells (MFCs) and potential integration of a MFC into an anaerobic biofiltration system.

Evelyn January 2013 (has links)
Microbial fuel cells (MFCs) are emerging energy production technology which converts the chemical energy stored in biologically degradable compounds to electricity at high efficiencies. Microbial fuel cells have some advantages such as use of an inexpensive catalyst, operate under mild reaction conditions (i.e. ambient temperature, normal pressure and neutral pH), and generate power from a wide range and cheap raw materials. These make microbial fuel cell as an attractive alternative over other electricity generating devices. However, so far the major problem posses by this technology is the low power outputs of the microbial fuel cells that hinder its commercialization. Restriction in the electron transfer from bacteria to the anode electrode of a MFC is thought to be one cause for the low power output. Most recent MFC research is focused on using contaminants present in industrial, agricultural, and municipal wastewater as the energy source, with very few studies utilising gaseous substrates. Mediators can be added to MFCs to enhance the electron transfer from the microbe to the anode, but have limited practical applicability in wastewater applications because of the difficulty in recovering the expensive and potentially toxic compound. This thesis describes an investigation of electricity generation in a microbial fuel cell by combining a gaseous substrate with a mediator in the anode compartment. The emphasis being placed on the selection of a mediator to improve the electron transfer process for electricity production in an MFC. Subsequently, methods to improve the performance of a mediator MFC in respect of power and current density were discussed. This type of MFC is purposely aimed to be applied for treating gaseous contaminants in an anaerobic biofilter while simultaneously produce electricity. In this study, ethanol was the first gaseous substrate tested for the possibility to generate electricity in the MFC. Various mediators were previously compared in their reversibility of redox reactions and in the current production, and three best mediators were then selected for the power production. The highest electrical current production i.e. 12 μA/cm2 was obtained and sustained for 24 hrs with N,N,N',N'-tetramethyl-1,4- phenylendiamine TMPD (N-TMPD) as the mediator using glassy carbon (GC) electrode. The maximum power density reached 0.16 mW/cm2 by using carbon cloth (CC) anode. The absorption of these mediators by the bacterial cells was shown to correlate with the obtained energy production, with no N-TMPD was absorbed by the bacterial cells. The 24 hr current production was shown to be accompanied by the decrease in the ethanol concentration (i.e. 1.82 g/L), however ethanol crossover through the proton exchange membrane and ethanol evaporation around the electrodes were most likely to be the major cause of the decrease in the ethanol concentration. A theoretical coulombic efficiency of 0.005% was calculated for this system. The electrokinetics of microbial reduced mediator in the ethanol-mediator MFCs was also examined. Two methods i.e. linear sweep voltammetry (LSV) and cyclic voltammetry (CV) were used to obtained the kinetic parameters. CV method gave a better estimation of the kinetic parameters than LSV method due to the low concentration of the mediators used, affecting the Tafel behaviors. All CVs showed quasi-reversible behaviors compared to the CVs in the absence of the bacteria, which is thought due to the bacteria decreased the amount of the reduced and the oxidised mediator available at the surface of GC electrode. The highest exchange current density (i o ) was obtained by using N-TMPD as the mediator with the same concentration of the mediator used i.e. 0.13±0.01 mA/cm 2. The power output achieved also the highest (0.008 mW/cm 2) with N-TMPD as the mediator. The power density was improved to 0.03 mW/cm2 by using CC electrode. Another main objective of this thesis is to prove anoxic methane oxidation which was believed to occur only in marine sediments, and applies this for power generation in microbial fuel cells. Ferricyanide looked promising when it was used as the electron acceptor (thus as the mediator for the MFC). It was shown that ferricyanide was fully reduced by methanotrophs bacteria with methane as the substrate (versus abiotic and nitrogen control). The highest reduction rate achieved was 3 x10-3 mM/min.g. This finding was supported by ferricyanide peak heights disappearance (spectrophotometry at 420 nm), CO 2 production (sensor readings), ferrocyanide formation (cyclic voltammetry), and no other alternate electron acceptor was present. The total CO 2 produced was equal to 0.015 mmoles of CO 2 from starting concentration ferricyanide of 0.2 mmoles (after substraction with an offset value). CV results show 2.4 mM of ferrocyanide was produced after a total addition of 3 mM ferricyanide into the anoxic methanotrophic suspension. The current and voltage generation in microbial fuel cell reactor from the reduced ferricyanide confirmed that ferricyanide received electrons from the bacterial metabolism. The maximum power density of 0.02 mW/cm2 and OCV of 0.6 V were obtained with 3 mM ferricyanide using LSV method.
12

Amperometrinių biologinių jutiklių (biosensorių) iš mielių ląstelių kūrimas, naudojant mediatorių fenazinmetasulfatą / Amperometric biosensors for lactic acid based on yeast cells and mediator Phenazine metosulphate

Kalionova, Natalija 16 August 2007 (has links)
Elektrocheminiai matavimai atlikti kambario temperatūroje, trijų elektrodų celėje, kuri matavimų metu buvo laikyta tamsoje (FMS jautrus šviesai). Darbiniu elektrodu panaudotas sukurtas iš mielių ląstelių biojutiklis, pagalbiniu Pt – elektrodas ir sidabro chloridinis – kaip palyginamasis elektrodas. Potenciodinaminiu bei potenciostatiniu metodais ištirti įvairių modifikacijų jutikliai. Gauti duomenis fiksuojami kompiuteriu programoje BAS Epsilon EC-2000-XP ( Ver.1,50,69_XP) ir analizuojami. Parinkome labiausiai tinkantį jutiklio modifikacijos būdą L-pieno rūgšties nustatymui ir įvertinome įvairių veiksnių įtaką oksidacinių srovių stipriui bei rezultatų stabilumui. Ištyrėme biojutiklio veikimą natūralioje aplinkoje. Kaip natūralius L-pieno rūgšties šaltinius panaudojome tokius pieno produktus, kaip jogurtas ir kefyras. Tyrimų metu nustatyta, kad optimaliausios sąlygos biologinio jutiklio veikimui yra: Econst.0 V, sausos mielių ląstelės iš suspensijos adsorbuotos ant jutiklio pavir��iaus, 0,2 mmol/l FMS tirpalas fosfatiniame buferyje, pH7,2. Darbo privalumas yra tas, kad jutiklių kūrimui panaudotas pigus fermento flavocitochromo b2 šaltinis – mielių ląstelės. Trūkumas – stiprus triukšmingumas, kas padidina jutiklio nustatymo ribas ( jutiklis tampa jautrus kitiems substratams) ir ilgas laikas, kol pasiekiamas stabilus rezultatas. / Electrochemical measurements were performed in a three-electrode cell arranged with a magnetic stirrer. Carbon paste electrode served as a working electrode. Platinum wire and Ag/ AgCl, 3 NaCl were, respectively, counter and reference electrodes. All measurements were performed with BAS-Epsilon Bioanalytical system. This work presents investigation of carbon paste electrodes modified with commercially available yeasts as amperometric biosensors for lactic acid using a mediator phenazine methosulphate (PMS). Sensitivity to lactic acid was tested using various configurations of the electrodes (yeast layer on the top of the electrode, yeast in the bulk carbon paste, PMS in solution or in the bulk carbon paste). The optimal operational conditions of the electrodes were: an operating potential 0.0 V, solution pH 7.2, concentration of phenazine methosulphate in solution 0.2 mmol/l, and yeast layer on the top of the electrode. The suitability of yeast-modified electrodes for determination of L-lactic acid in milk and dairy products such as kefir and yoghurt was also tested. The advantages of the electrodes were the simple preparation from the cheap source of the enzyme flavocytochrome b2. The disadvantages of the electrodes were long time to achieve reproducible results, high noise level, thus, high detection limit and sensitivity to other metabolites.
13

Amperometrinių biojutiklių (biosensorių) kūrimas iš mielių ląstelių naudojant mediatorių fericianidą / Development of amperometric biosensors for lactic acid based on yeastcells and mediator fericyanide

Andriuškevičiūtė, Diana 16 August 2007 (has links)
Šio darbo tikslas, buvo pagaminti stabilų elektrodą naudojant džiovintas ir „gyvas“ mielių ląsteles. Tyrimo metu buvo naudojama trijų elektrodų celė: darbinis anglies elektrodas, pagalbinis platinos elektrodas ir Ag/AgCl elektrodas. Visos potencialų vertės tiesiogiai nurodytos palyginamojo elektrodo atžvilgiu. Tyrimo metu ištyrėme biologinių jutiklių oksidacinių srovių stiprio priklausomybę nuo L-pieno rūgšties koncentracijos naudojant įvairius koncentracijų mediatorius. Nustatėme, kad didėjant mediatoriaus koncentracijai nuo 0,5-1,0-1,5 mM elektrodo stabilumas ir pasikartojamumas didėja. Be to, ištyrėme oksidacinių srovių priklausomybę nuo L-pieno rūgšties naudojant įvairių modifikacijų biologinius jutiklius. Nustatėme, kad stabilus elektrodas gaunamas tik tuo atveju jeigu, naudojame modifikuotas džiovintas mieles ant elektrodo paviršiaus. Taipogi iš gautų kreivių nustatėme, potencialo įtaka oksidacinių srovių stipriui. Visais atvejais prie visų potencialų stebima L-pieno rūgšties oksidaciją bet vis dėl to, skiriasi oksidacinių srovių skaitinės reikšmės. Darbo tikslas įvykdytas nes, pavyko gauti stabilu elektrodą, kurio jautrumą L-pieno rūgščiai patikrinome kefyro ir jogurto pagalba. / The purpose of this research paper, was to create a stable electrode using dry and „alive“ cells of yeast. During the research we used cell of three electrodes: working carbon electrode, supportive platin electrode and Ag/AgCl electrode. All potential values are directly shown in relation to comparison electrode. During the research we have tested the dependence of biosensors oxidical streams strength upon L-milk acid concentration using various concentration mediators. We have established, that increasing mediators concentration from 0.5-1.0-1.5 mM stability and recurrence of electrode is increasing. Furthermore, we have tested the dependence of oxidical streams upon L-milk acid using various modification biosensors. We have established that it is possible to get stable electrode only if using modificated dry yeast on electrode surface. Also from curves we have found, we established the influence of potential on strength of oxidical streams. In all cases, we could notice oxidation of L-milk acid with every potential, however there is difference in oxidical streams numerical values. The research was succesful, as we succeeded in getting stable electrode, the sensitivity of which we have checked with use of sour milk and yogurt.
14

Ar mediatoriaus konfidencialumo pareiga mediacijoje yra absoliuti? / Is the duty of confidentiality placed upon mediators absolute?

Trakanavičienė, Rūta 31 July 2009 (has links)
Konfidencialumas – tai svarbiausias mediacijos proceso bruožas, išskiriantis mediaciją iš kitų ginčų sprendimo procedūrų. Egzistuoja bendra taisyklė, kad visa rašytinė ir žodinė informacija atskleista mediacijos metu laikoma konfidencialia. Ginčo šalys, mediatoriai ir kiti mediacijos dalyviai įpareigojami laikyti paslaptyje ir neatskleisti informacijos susijusios su mediacija. Sėkminga mediacija paremta šalių pasitikėjimu bei atvirumu. Ginčo šalis nebijos atskleisti informacijos tik tuomet kai žinos, kad ta informacija nebus panaudota prieš ją pačią vėlesniame teismo ar arbitražo procese. Konfidencialumas skatina mediacijos proceso efektyvumą bei užtikrina mediatoriaus neutralumo ir nešališkumo reikalavimus. Europos Sąjungos institucijos įvertino mediacijos svarbą siekiant vieno iš pagrindinių ES politinių tikslų – teismų prieinamumo didinimo. Mediacija kaip neteisminė taikaus ginčų sureguliavimo procedūra gali perimti dalį ginčų ir taip tiesiogiai prisidėti prie teismų prieinamumo didinimo. ES institucijos priėmė eilę teisinių instrumentų - kaip Žalioji knyga, Europos mediatorių elgesio kodeksas, Europos Parlamento ir Tarybos Direktyva 2008/52/EB dėl tam tikrų mediacijos civilinėse ir komercinėse bylose aspektų – kurių tikslas paskatinti bei suvienodinti mediacijos taikymą ES valstybėse narėse. Direktyva pabrėžia konfidencialumo svarbą mediacijoje ir nustato minimalius standartus užtikrinančius konfidencialumo apsaugą. Lietuva iki 2011 m. privalės tinkamai... [toliau žr. visą tekstą] / Modern Western states declaring the right to fair and speedy trial have faced serious obstacles while implementing it. The judicial procedure is suffering from severe caseload leading to a substantial delay and increasing costs in litigation. The situation resulted in growing public dissatisfaction with the formal court system and a justice as a whole. This encouraged the states to look for new dispute resolution mechanisms which could be alternative to litigation and could overtake certain disputes from courts leaving access to justice more available. In 1950’s USA introduced mediation in solving labor disputes. It showed a success and gained the support of legislation and judiciary which led to wide spread of mediation to other areas of dispute resolution: small claims, neighborhood, consumer, landlord-tenant, victim-offender, family, environmental disputes. Mediation can offer a cheaper, faster, less formal procedure compared to litigation. Mediation leaves the ultimate decision making process in the hands of the parties themselves. The third neutral person is only assisting the parties in developing the dialogue and reaching a mutually acceptable settlement of issues in dispute. This voluntarily reached settlement diminishes the friction between adverse parties, helps to maintain further amicable relations between parties and preserve the social peace and harmony. Confidentiality is regarded as a fundamental feature to effective mediation. It encourages candid and free... [to full text]
15

Medlaren i fokus : Upplevelsen av att genomföra medling vid brott

Avermark, Annie January 2014 (has links)
No description available.
16

Using document clustering and language modelling in mediated information retrieval

Muresan, Gheorghe January 2002 (has links)
Our work addresses a well documented problem: users are frequently unable to articulate a query that clearly and comprehensively expresses their information need. This can be attributed to the information need being too ambiguous and not clearly defined in the user's mind, to a lack of knowledge of the domain of interest on the part of the user, to a lack of understanding of a retrieval system's conceptual model, or to an inability to use a certain query syntax. This thesis proposes a software tool that emulates the human search mediator. It helps a user explore a domain of interest, learn its structure, terminology and key concepts, and clarify and refine an information need. It can also help a user generate high-quality queries for searching the World Wide Web or other such large and heterogeneous document collections. Our work was inspired by library studies which have highlighted the role of the librarian in helping the user explore her information need, define the problem to be solved, articulate a formulation of the information need and adapt it for the retrieval system at hand in order to get information. Our approach, mediated access through a clustered collection, is based on an information access environment in which the user can explore a relatively small, well structured, pre-clustered document collection covering a particular subject domain, in order to understand the concepts encompassed and to clarify and refine her information need. At the same time, the user can ostensively indicate clusters and documents of interest so that the system builds a model of the user's topic of interest. Based on this model, the system assists and guides the user's exploration, or generates `mediated queries' that can be used to search other collections. We present the design and evaluation of WebCluster, a system that reifies the concept of mediated retrieval. Additionally, a variety of mediation experiments are presented,which provide guidelines as to which mediation strategies are more appropriate for different types of tasks. A set of experiments is presented that evaluate document clustering's capacity to group together topical documents and support mediation. In this context we propose and experimentally test a new formulation for the cluster hypothesis. We also look at the ability of language models to convey content, to represent topics and to highlight specific concepts in a given context. They are also successfully applied to generate flexible, task-dependent cluster representatives for supporting exploration through browsing and respectively searching. Our experimental results show that mediation has potential to significantly improve user queries and consequently the retrieval effectiveness.
17

Studien zur physiologischen Funktion löslicher Zytokinrezeptoren und zur Wirkungsweise viral kodierter Zytokine

Jostock, Thomas. January 2001 (has links) (PDF)
Mainz, Univ., Diss., 2001.
18

A, a'-Dicarbonyl-Oxime Eigenschaften und Anwendungen in der elektrochemischen Delignifizierung /

Kim, Hee-Cheol. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2001--Marburg.
19

Two alleles of Med31 provide a model to study delayed fetal growth, proliferation and placental development

Wolton, Kathryn January 2016 (has links)
Fetal growth restriction (FGR) is the failure of a fetus to reach its pre-determined genetic growth potential during development. FGR is associated both with poor outcome in the neonatal period, and the onset of major adult diseases such as diabetes, hypertension and obesity. Therefore understanding what causes restricted fetal growth is important both for improving neonatal health, and for the minimization of major worldwide healthcare burdens. Described here are two mutant mouse lines, each with a distinct mutation in the Mediator complex gene Med31. These mutations result in reduced fetal growth, allowing for the investigation of the role of Med31 in the proper control of growth during development. The first mutant mouse line (Med31 Null) carries a C/T point mutation in exon 4 of Med31. Homozygous mutant embryos display reduced growth during development, characterized by their reduced size and smaller forelimbs compared to their heterozygous littermate controls. The second mutant mouse line (Med31 Y57C) carries a T/C point mutation in exon 3 of Med31. Similarly, homozygous mutant embryos display reduced fetal growth with reductions in forelimb length compared to their heterozygous littermate controls. In both mutant lines whole embryo growth and endochondral ossification within the limbs is perturbed. This is due to defects in cellular proliferation and the misexpression of the cell cycle genes Ccnb1 and Mtor within the mutant embryos. Additionally, the Med31 Null line is embryonic lethal by E18.5 and displays morphological defects of the placenta compared to heterozygous littermate controls. These morphological differences are suggestive of defects in the function of the placenta, and are proposed as the cause of embryonic lethality. In support of this the Med31 Y57C line is viable with no defects in placental development. New roles for Med31 in embryonic growth, cellular proliferation and placental development are identified. Moreover the two mutant lines constitue an allelic series of Med31, and the two mutations provide insights into the various ways Med31 is able to regulate transcription during development.
20

Mediace jako alternativní způsob řešení sporů / Mediation as an alternative manner of dispute resolution

Římanová, Hana January 2016 (has links)
71 Abstract Mediation as an alternative manner of dispute resolution The topic of this thesis is mediation, as a form of settlement solution carried out of court. Mediation is in the Czech Republic still very topical. Its growing use can help to reduce the workload of courts. The aim of this thesis was to introduce mediation in general, to discuss the legal regulation of mediation in civil cases in the Czech Republic and critically analyse it. Apart the introduction and conclusion the thesis contains seven chapters in total. The first chapter defines mediation as one of the alternative methods of dispute resolution. Subsections provide a definition of mediation, comparison between mediation and court and arbitration proceedings, and discuss the benefits of resolving the dispute through mediation. The second chapter is focused on the development of mediation. After a brief introduction, it deals with the development of mediation in the United States, Europe and finally in the Czech Republic. Subsequent chapters describe mediation method itself and its theoretical bases. The third chapter discusses the fundamental principles that are applied in the mediation. The fourth chapter provides the basic definition of mediation styles. The following chapter discusses a mediator, his qualification, role,...

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