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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.
1

Source Zone Mass Depletion of Chlorinated Aliphatic Hydrocarbons: Estimation of Rates and Insight into Source Architecture

January 2013 (has links)
abstract: This work focuses on a generalized assessment of source zone natural attenuation (SZNA) at chlorinated aliphatic hydrocarbon (CAH) impacted sites. Given the numbers of sites and technical challenges for cleanup there is a need for a SZNA method at CAH impacted sites. The method anticipates that decision makers will be interested in the following questions: 1-Is SZNA occurring and what processes contribute? 2-What are the current SZNA rates? 3-What are the longer-term implications? The approach is macroscopic and uses multiple lines-of-evidence. An in-depth application of the generalized non-site specific method over multiple site events, with sampling refinement approaches applied for improving SZNA estimates, at three CAH impacted sites is presented with a focus on discharge rates for four events over approximately three years (Site 1:2.9, 8.4, 4.9, 2.8kg/yr as PCE, Site 2:1.6, 2.2, 1.7, 1.1kg/y as PCE, Site 3:570, 590, 250, 240kg/y as TCE). When applying the generalized CAH-SZNA method, it is likely that different practitioners will not sample a site similarly, especially regarding sampling density on a groundwater transect. Calculation of SZNA rates is affected by contaminant spatial variability with reference to transect sampling intervals and density with variations in either resulting in different mass discharge estimates. The effects on discharge estimates from varied sampling densities and spacings were examined to develop heuristic sampling guidelines with practical site sampling densities; the guidelines aim to reduce the variability in discharge estimates due to different sampling approaches and to improve confidence in SZNA rates allowing decision-makers to place the rates in perspective and determine a course of action based on remedial goals. Finally bench scale testing was used to address longer term questions; specifically the nature and extent of source architecture. A rapid in-situ disturbance method was developed using a bench-scale apparatus. The approach allows for rapid identification of the presence of DNAPL using several common pilot scale technologies (ISCO, air-sparging, water-injection) and can identify relevant source architectural features (ganglia, pools, dissolved source). Understanding of source architecture and identification of DNAPL containing regions greatly enhances site conceptualization models, improving estimated time frames for SZNA, and possibly improving design of remedial systems. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2013
2

Betydelsen av att vila 15 minuter innan provtagning för kalium- och natriumanalyser i plasma / The importance of resting 15 minutes before collecting blood samples of potassium and sodium in plasma

Almkvist, Erik January 2021 (has links)
Enligt svenska provtagningsanvisningar bör patienter vila i sittande ställning i minst 15 minuter innan provtagningen sker för att optimera resultatet av analysen. Referensintervallen som existerar idag i Sverige för olika analyser är framtagna och baserade på prover som tagits efter att deltagarna vilat 15 minuter i sittande position innan provtagningen. I denna studie samlades venösa blodprover in från patienter och personal i Karlskoga lasarett. Statistiska beräkningar utfördes för att jämföra kalium- och natriumanalyser i plasma efter att deltagaren vilat 15 minuter gentemot att deltagaren tagit en promenad på cirka 50 meter, signifikansnivån bestämdes som 0,05. Analyserna mättes genom en indirekt potentiometrisk metod, ISE, på instrumentet Advia 1800 Chemistry. Resultatet visade att det finns en signifikant skillnad av att vila 15 minuter innan provtagningen äger rum för kalium- och natriumanalyser i plasma gentemot att inte vila. Trots att studien visar att det finns en signifikant skillnad av att patienter vilar 15 minuter innan provtagningen sker är skillnaden inte tillräckligt stor för att påverka resultatet på ett sätt som förändrar läkarbedömningen. Personal bör ändå följa provtagningsanvisningarna för att optimera trovärdigheten och resultatet av analysen. / Swedish sampling guidelines encourage patients to rest for 15 minutes in a sitting position before drawing blood in order to optimize the results of the analysis. The reference ranges that is used for different blood tests in Sweden are originally based on samples taken from participants that has been resting 15 minutes in a sitting position. In this study, venous blood samples were collected from patients and staff in Karlskoga hospital. Statistical calculations was performed in order to compare potassium- and sodiumanalyzes in plasma after resting 15 minutes and after a stroll of 50 meters. The significance level was set to 0,05. The analyzes were measured using an indirectly potentiometric method, ISE, on the instrument Advia 1800 Chemistry. The study found that there is a significant difference by resting 15 minutes in a sitting position before drawing blood in order to analyze potassium and sodium compared to not resting. The difference between resting for 15 minutes in a sitting position before sampling, and not resting, is not large enough to affect the medical assessment of the analysis. However, hospital staff should still follow the Swedish sampling guidelines in order to optimize the credibility of the analysis.

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