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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.
61

Utvärdering av processen vid Hofors vattenverk med avseende på avskiljning av NOM – fällning och membranfilterteknik / Evaluation of the process at Hofors water treatment plant with respect to the separation of NOM - flocculation and membrane filtration technology

Tirén Ström, Julia January 2016 (has links)
De senaste årtiondena har en ökning av naturligt organiskt material (NOM) observerats i ytvatten i norra Europa och Nordamerika. NOM i vattnet innebär utmaningar för vattenverk som använder ytvatten i dricksvattenproduktionen då det kan ge upphov till lukt, smak och färg och svårigheter i driften. För att åtgärda och förebygga problemen behövs mer kunskap om NOM samt hur kvantiteten och sammansättningen förändras i olika reningsprocesser. Vid Hofors vattenverk används råvatten från sjön Hyen i dricksvattenproduktionen. Driftstörningar upplevs i perioder då råvattnets färgtal (mått på halten NOM) är högt. Därför undersöktes det hur väl den nuvarande reningsprocessen vid Hofors vattenverk fungerar med avseende på avskiljning av NOM samt vilken typ av NOM som avskiljs. Resultaten jämfördes med pilotförsök med direktfällning på ultrafiltermembran för att se om detta kan ge bättre avskiljning. Olika analysmetoder, absorbans, fluorescens och mätning av löst organiskt kol (DOC), användes för att avgöra kvantitet och karaktär på NOM i vattenproverna. Även eventuell förekomst av trend i råvattnets färgtal undersöktes. Likt i många andra ytvatten har färgtalet i Hyen har ökat de senaste åren (1997-2015). Råvattnet är svårfällt och innehåller en blandning av olika NOM-fraktioner. Huvudsakligen avskiljs humuslikt, alloktont NOM i Hofors vattenverk. Avskiljningen var störst i första reningssteget, direktfällning på sandfilter. Förändringen i efterföljande reningssteg, kolfilter samt desinfektions- och pH-höjande steg, var dock svår att bestämma till följd av mycket små förändringar och motsägande analysresultat. Tre ultrafiltermembranförsök gav liknande avskiljningsresultat som sandfilter, men i två av fallen är det troligt att igensättning av membranen spelade in. Det krävs ytterligare försök för att säkert uttala sig om huruvida ultrafiltermembran är en teknik som är lämplig att använda vid Hofors vattenverk i framtiden för avskiljning av NOM. / In recent decades, an increase in natural organic matter (NOM) has been observed in surface waters in Northern Europe and North America. NOM in the water poses challenges for water treatment plants (WTP) using surface water in the drinking water production. It can cause odor, taste and color of the water and cause difficulties in the treatment process. To prevent all these problems, more information about NOM and how the quantity and composition changes in various treatment processes is needed. At Hofors WTP, raw water from the lake Hyen is used in the production of drinking water. Disruptions in running the process have been experienced in periods when the raw water color (measure of the NOM content) has been high. In this thesis, it was investigated how well the current treatment process at Hofors WTP works with respect to the separation of NOM and what type of NOM that is separated. The results were compared with pilot tests with direct filtration using an ultrafilter membrane to see if this can provide better separation. Various analytical methods as absorbance, fluorescence and measurement of dissolved organic carbon (DOC) were used to quantify and determine the composition of NOM in the water samples. It was also examined whether there is a trend in the raw water color. As in many other surface waters the color of the water has increased in Hyen in recent years (1997-2015). The raw water contains a mixture of different NOM fractions and the character indicates difficulties in removing DOC by coagulation and flocculation. It is primarily the humic like, allochtonous NOM that is separated in the treatment process with the greatest separation in the first treatment step, direct filtration with sand filter. What happens in the subsequent treatment steps, carbon filter, disinfection and pH-raising step, was however unclear due to small changes and inconsistent analysis results. Three experiments with ultrafilter membrane yielded similar results as sand filters, but in two of the cases it is likely that clogging of the membranes contributed. Further membrane pilot tests are needed to be sure whether ultrafilter membrane is a is suitable technique to use at Hofors WTP in the future for separation of NOM.
62

Modeling, Design, Fabrication, and Characterization of a Highly Sensitive Fluorescence-based Detection Platform for Point-of-Care Applications

January 2018 (has links)
abstract: Over the past several decades, there has been a growing interest in the use of fluorescent probes in low-cost diagnostic devices for resource-limited environments. This dissertation details the design, development, and deployment of an inexpensive, multiplexed, and quantitative, fluorescence-based lateral flow immunoassay platform, in light of the specific constraints associated with resource-limited settings. This effort grew out of the need to develop a highly sensitive, field-deployable platform to be used as a primary screening and early detection tool for serologic biomarkers for the high-risk human papillomavirus (hrHPV) infection. A hrHPV infection is a precursor for developing high-grade cervical intraepithelial neoplasia (CIN 2/3+). Early detection requires high sensitivity and a low limit-of-detection (LOD). To this end, the developed platform (DxArray) takes advantage of the specificity of immunoassays and the selectivity of fluorescence for early disease detection. The long term goal is to improve the quality of life for several hundred million women globally, at risk of being infected with hrHPV. The developed platform uses fluorescent labels over the gold-standard colorimetric labels in a compact, high-sensitivity lateral flow assay configuration. It is also compatible with POC settings as it substitutes expensive and bulky light sources for LEDs, low-light CMOS cameras, and photomultiplier tubes for photodiodes, in a transillumination architecture, and eliminates the need for expensive focusing/transfer optics. The platform uses high-quality interference filters at less than $1 each, enabling a rugged and robust design suitable for field use. The limit of detection (LOD) of the developed platform is within an order of magnitude of centralized laboratory diagnostic instruments. It enhances the LOD of absorbance or reflectometric and visual readout lateral flow assays by 2 - 3 orders of magnitude. This system could be applied toward any chemical or bioanalytical procedure that requires a high performance at low-cost. The knowledge and techniques developed in this effort is relevant to the community of researchers and industry developers looking to deploy inexpensive, quantitative, and highly sensitive diagnostic devices to resource-limited settings. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2018
63

Seasonal variation and landscape regulation of dissolved organic carbon concentrations and character in Swedish boreal streams

Ågren, Anneli January 2007 (has links)
The seasonal variation and landscape regulation of dissolved organic carbon (DOC) concentrations in streams have been studied in two watersheds in the boreal zone. The seasonal variation was found to be highly correlated to variations in runoff. An increase in runoff was always accompanied with an increase in DOC concentration. However, there were indications that the TOC concentration was restricted by the soil TOC pool during snowmelt. The main factors affecting DOC exports varied between seasons. During winter baseflow the spatial variation in DOC exports was strongly influenced by wetland coverage, during snowmelt the exports were correlated to factors describing the size and location of the catchment, and during the snow-free season they were heavily affected by the proportions of wetlands and forests in the catchments. Small headwaters had the highest terrestrial DOC export, per unit area. The properties of the DOC changed during spring flood, towards lower molecular weight and more aliphatic compounds. These changes affected the bioavailability of the DOC, which increased during spring flood. There were also differences in the DOC properties between wetlands and forest soils; the forested soils yielded DOC with lower molecular weight (measured as 254 nm/365 nm light absorbance ratios), largely from superficial layers that were activated during high flow events, while wetland soils generally provided a more constant carbon source with higher molecular weight. The majority of the DOC was exported by wetlands, but most of the short-term bioavailable DOC (BP7) was derived from the forests, during the spring flood period, indicating that bacterial production in streams and lakes is likely to be almost entirely based on DOC exported from forested areas during, and some time after, the spring flood event.
64

Měření absorbance moči při indikaci Mn2+ / Measurement of urine absorbance with indicator Mn2+

KONEČNÝ, Jan January 2013 (has links)
Measurement of urine absorbance which has been irradiate by a dose of ionising radiation with addition of Mn2+ should serve to find the dose of radiation. This method could work quickly and reliably for homogeneous irradiation of person or as a rough estimate of the dose which the person received during a radiation accident. This method should serve for quick classification of the person. The target of this thesis is to find out if the irradiated urine with the addition of a solution of manganese chloride will change absorbance according to radiation dose. And if urine can be used as a biological dosimeter. In the theoretical part I describe the basic areas related to the topic and target of my thesis. This part is divided to seven subchapters: ionising radiation, radiation protection, radiotherapy, particle accelerators, spectrophotometry, excretion and urine, and dosimetry and its methods. Methods of this thesis are not clear. I tried different procedures during experiments with different results. First, I always prepared samples of urine in tubes and irradiated it in a linear accelerator Clinac 2100C/D in České Budějovice, a.s. hospital with doses from 1 to 25 Gy. Before each measurement I had two sets of tubes with these doses: 0, 1, 2, 3, 5, 7, 10, 15, 20 and 25 Gy. The following procedure was different in each experiment. Sometimes I tried adding a solution of manganese chloride to all tubes at once. Sometimes I tried to adding a solution of manganese chloride to each tube separately. I added the solution to irradiated urine at various concentrations of solution (from 1 do 5 mols) and different amounts (from 1 to 3 ml). Another difference was the use of centrifuges. A centrifuge was use in about half of experiments. Other measurements were made without centrifugation.In discussion I propose recommended methods. I recommend measuring only without centrifuges. Each cell should be measured as soon as possible after irradiation and simultaneously as soon as possible after adding the solution of manganese chloride. Results of the thesis are not clear. Only some experiments which were measuring with centrifuge were clear. I can say that this method does not work when a centrifuge is used at any tested concentration of solution of manganese chloride. The absorbance of single doses of ionising radiation does not change and the values were the same when using 1M, 3M and 5M solutions of MnCl2. The resulting graphs from all experiments have a constant absorbance value of all measured doses. (subchapter 3.1).In the remaining experiments measured without the centrifuge the results were much more interesting. In some experiments the measured absorbance really changed with the dose of ionising radiation so the hypothesis of this study was confirmed. But the differences were too small for this method to be used for measuring radiation doses (subchapter 3.2).The results were compared with the results of the thesis ?Measurement of urine extinction in depending on ionising radiation? from author Š. Radová. She performed a similar experiment, but with a different indicator - FeSO4. 7 H20. It was found that the indicator FeSO4. 7 H20 is preferable to measuring doses of ionising radiation in urine. In conclusion I can say that the hypothesis of this study was confirmed, but the method could not be used in practice and irradiated urine with added MnCl2 indicator does not function as a biological dosimeter.
65

Reciclagem de material asf?ltico fresado utilizando solventes e microemuls?es

Gomes Filho, Fernando Francisco 30 December 2009 (has links)
Made available in DSpace on 2014-12-17T15:01:21Z (GMT). No. of bitstreams: 1 FernandoFGF.pdf: 1543921 bytes, checksum: 28fee7b00926ff19375c7b0098bc6b3d (MD5) Previous issue date: 2009-12-30 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / With the increase of asphalt milling services was also a significant increase in recycling services pavements. The techniques used today are basically physical processes in which the milled material is incorporated into new asphalt mixtures or executed on site, with the addition of virgin asphalt and rejuvenating agent. In this paper seeks to analyze the efficiency of extraction of CAP (Petroleum Asphalt Cement) mixtures from asphalt milling, using commercial solvents and microemulsions. The solvents were evaluated for their ability to solubilize asphalt using an extractor reflux-type apparatus. Pseudoternary diagrams were developed for the preparation of microemulsion O/W surfactant using a low-cost coconut oil saponified (OCS). Microemulsions were used to extract the CAP of asphalt through physicochemical process cold. Analysis was performed concentration of CAP in solution by spectroscopy. The data provided in the analysis of concentration by the absorbance of the solution as the basis for calculating the percentage of extraction and the mass flow of the CAP in the solution. The results showed that microemulsions prepared with low concentration of kerosene and butanol/OCS binary has high extraction power of CAP and its efficiency was higher than pure kerosene, reaching 95% rate of extraction / Com o aumento dos servi?os de fresagem asf?ltica houve tamb?m um incremento significativo nos servi?os de reciclagem de pavimentos asf?lticos. As t?cnicas hoje empregadas s?o basicamente processos f?sicos nas quais o material fresado ? incorporado a novas misturas asf?lticas ou executado in loco , com a incorpora??o de asfalto virgem e agente rejuvenecedor. Nesse trabalho prop?e-se analisar a efici?ncia na extra??o do CAP (Cimento Asf?ltico de Petr?leo) de misturas proveniente de fresagem asf?ltica, utilizando solventes comerciais e microemuls?es. Os solventes foram avaliados quanto a sua capacidade de solubilizar asfalto utilizando um extrator por refluxo do tipo Soxhlet. Foram desenvolvidos diagramas pseudotern?rios para elabora??o de microemuls?o O/A utilizando tensoativo de baixo custo como o ?leo de coco saponificado (OCS). As microemuls?es foram utilizadas para extrair o CAP da mistura betuminosa atrav?s de processo f?sico-qu?mico a frio. Foi realizada an?lise de concentra??o de CAP na solu??o atrav?s de espectroscopia. Os dados fornecidos na an?lise da concentra??o atrav?s da absorb?ncia da solu??o serviram de base para o c?lculo do percentual de extra??o e do fluxo m?ssico do CAP na solu??o. Os resultados mostraram que microemuls?es elaboradas com baixa concentra??o de querosene e do bin?rio butanol/OCS tem grande poder de extra??o de CAP, sua efici?ncia foi maior do que o querosene puro, alcan?ando taxa de 95% de extra??o
66

[en] CHARACTERIZATION AND KINETIC STUDIES OF ALBUMIN TREATED WITH NITROGEN OXIDE DERIVED REACTIVE SPECIES: ABSORPTION SPECTROSCOPY AND FLUORESCENCE / [pt] CARACTERIZAÇÃO E ESTUDOS CINÉTICOS DE ALBUMINA TRATADA COM ESPÉCIES REATIVAS DERIVADAS DE ÓXIDOS DE NITROGÊNIO: ESPECTROSCOPIA DE ABSORÇÃO E FLUORESCÊNCIA

LUIZ DA SILVA GOES FILHO 29 March 2006 (has links)
[pt] A descoberta da importância do óxido nítrico na fisiologia humana expandiu a investigação dos mecanismos de interação das espécies reativas derivadas de óxidos de nitrogênio com biomoléculas. S-nitrosotióis são uma fonte conveniente de óxido nítrico para utilização in vivo. Um dos métodos largamente utilizados para S-nitrosilação de compostos contendo o grupo -SH, incluindo proteínas contendo o aminoácido cisteína, é a reação com nitrito em meio ácido. Nesse trabalho investigaram-se as espécies derivadas da reação de albumina sérica, humana e bovina, e de insulina com nitrito, através de espectrofotometria de absorção e de fluorescência. Além da modificação dos resíduos de cisteína, demonstrou-se que resíduos do aminoácido triptofano também sofrem modificação, podendo participar dos processos in vivo. A partir da comparação entre os espectros de absorção dos cromóforos formados em albumina humana e bovina, bem como em insulina, demonstrou-se que a banda de absorção no ultravioleta, descrita na literatura como característica de S-nitrosilação de cisteína, é dominada pelos resíduos de triptofano N-nitrosados. Experimentos de fluorescência confirmaram a modificação dos resíduos de triptofano, já que os espectros apresentaram redução do rendimento quântico e também deslocamento do pico característico desses resíduos. Acompanhou-se a cinética de formação de novos cromóforos, comparando as albuminas nativas e bloqueadas no resíduo de cisteína. Investigou-se a cinética de modificação dos resíduos de triptofano em pH fisiológico através de fluorescência. / [en] The discovery of the importance of nitric oxide to the human physiology expanded the investigation of mechanisms involved in the interactions of nitrogen oxide reactive species with biomolecules. S-nitrosothiols are a convenient source of nitric oxide for in vivo applications. Acid treatment with nitrite of compounds containing the SH group, including proteins containing cysteine residues, is a widely used method to synthesize S-nitrosothiols. In this work, several species derived from the nitrite acid treatment of human and serum albumins as well as insulin were investigated using optical absorption and fluorescence. It was demonstrated that, besides cysteine, tryptophan residues are modified and can participate in processes in vivo. Comparing the absorption spectra from human and bovine serum albumin with that from insulin, it was demonstrated that the ultraviolet absorption band, described in the literature as coming from Snitrosylation, was mainly due to N-nitrosation of tryptophan residues. Fluorescence experiments confirmed the modification of tryptophan residues, since the characteristic fluorescence peak exhibited a reduction and a blue shift. The kinetics of the new chromophores was followed by comparison of native and cysteine-blocked albumins. The kinetics of tryptophan modifications was investigated at the physiological pH using fluorescence.
67

Impact of operating conditions on thermal hydrolysis pre-treated digestion return liquor

Ahuja, Nandita 23 September 2015 (has links)
Return liquor from thermal hydrolysis process (THP) can significantly add to the nitrogen load of a wastewater treatment plant (WWTP) and introduce UV quenching substances to the wastewater stream when recycled. While there are mature technologies in place to handle the inorganic nitrogen produced due to the thermal pretreatment, organic nitrogen remains a parameter of concern for utilities employing THP pretreatment. The impact of operating conditions of the THP on dissolved organic nitrogen (DON) and UV absorbance in return liquor was investigated. Operating conditions studied were (1) operating temperature (2) solids retention time (SRT) in the anaerobic digester (3) THP flash pressure (4) the effect of co-digestion of sewage sludge with food waste and, (5) polymer conditioning. Operating temperature and polymer dose had the most significant impact on DON and UV quenching. It was found that an increase in operating temperature resulted in an increase in DON, which was primarily contributed by the hydrophilic fraction. An increase in temperature also resulted in increased UV254 absorbance. However, this trend was not linear and the increase was more pronounced when the temperature was increased from 150 C to 170 C. Increasing flash pressure from 25 psi to 45 psi did not have a significant impact on the return liquor. However, increasing the flash pressure to 75 psi increased the DON and UV254 absorbing compounds. Co-digesting the sludge with food waste resulted in a slight increase in DON and a decrease in dissolved organic carbon (DOC) and UV quenching compounds. Increasing the SRT from 10 days to 15 days resulted in a slight decrease in DON but did not have any impact on UV254 absorbance. Overall, it can be concluded that optimizing operating conditions of thermal hydrolysis process can result in decreased DON and UV quenching compounds in the recycle stream. / Master of Science
68

Treatment of Dye Wastewater using Dehydrated Peanut Hull

Shamirpet, Nikitha 27 July 2018 (has links)
No description available.
69

Investigating the Role of Subunit III in the Structure and Function of Rhodobacter Sphaeroides Cytochrome C Oxidase

Geyer, R. Ryan 31 July 2007 (has links)
No description available.
70

Two - Stage AnMBR for Removal of UV Quenching Organic Carbon from Landfill Leachates: Feasibility and Microbial Community Analyses

Pathak, Ankit Bidhan 13 February 2017 (has links)
Landfilling is the most widely used method for the disposal of municipal solid wastes (MSW) in the United States due to its simplicity and low cost. According to the 2014 report on Advancing Sustainable Materials Management by the USEPA, only 34% of the total MSW generated in the US was recycled, while 13% was combusted for energy recovery. In 2014, 53% of the MSW generated, (i.e. 136 million tons) in the US was landfilled. The treatment of landfill leachates, generated by percolation of water through the landfill, primarily due to precipitation, has been found to be one of the major challenges associated with landfill operation and management. Currently, leachates from most landfills are discharged into wastewater treatment plants, where they get treated along with domestic sewage. Issues associated with treatment of landfill leachates due to their high nitrogen and heavy metal content have been widely studied. Recently, it has been observed that the organic carbon in landfill leachates, specifically humic and fulvic acids (together referred to as "humic substances") contain aromatic groups that can absorb large amounts of ultraviolet (UV) light, greatly reducing the UV transmissivity in wastewater plants using UV disinfection as the final treatment step. This interference with UV disinfection is observed even when landfill leachates constitute a very small fraction (of the order of 1%) of the total volumetric flow into wastewater treatment plants. Humic substances are present as dissolved organic matter (DOM) and typically show very low biodegradability. Removing these substances using chemical treatment or membrane processes is an expensive proposition. However, the concentrations of humic substances are found to be reduced in leachates from landfill cells that have aged for several years, suggesting that these substances may be degraded under the conditions of long-term landfilling. The primary objective of this research was to use a two-stage process employing thermophilic pretreatment followed by a mesophilic anaerobic membrane bioreactor (AnMBR) to mimic the conditions of long-term landfilling. The AnMBR was designed to keep biomass inside the reactor and accelerate degradation of biologically recalcitrant organic carbon such as humic substances. The treatment goal was to reduce UV absorbance in raw landfill leachates, potentially providing landfills with an innovative on-site biological treatment option prior to discharging leachates into wastewater treatment plants. The system was operated over 14 months, during which time over 50% of UV-quenching organic carbon and 45% of UV absorbance was consistently removed. To the best of our knowledge, these removal values are higher than any reported using biological treatment in the literature. Comparative studies were also performed to evaluate the performance of this system in treating young leachates versus aged leachates. Next-generation DNA sequencing and quantitative PCR (qPCR) were used to characterize the microbial community in raw landfill leachates and the bioreactors treating landfill leachate. Analysis of microbial community structure and function revealed the presence of known degraders of humic substances in raw as well as treated landfill leachates. The total number of organisms in the bioreactors were found to be higher than in raw leachate. Gene markers corresponding to pathogenic bacteria and a variety of antibiotic resistance genes (ARGs) were detected in raw landfill leachates and the also in the reactors treating leachate, which makes it necessary to compare these ARG levels with wastewater treatment in order to determine if leachates can act as sources of ARG addition into wastewater treatment plants. In addition, the high UV absorbance of leachates could hinder the removal of ARBs and ARGs by UV disinfection, allowing their release into surface water bodies and aiding their proliferation in natural and engineered systems. / Ph. D.

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