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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.
41

Polarography Of Selected Metal Ions In Anhydrous Aliphatic Diamines

Foss, Frederick William, Jr. 01 January 1965 (has links) (PDF)
A search of the literature revealed that no study has sought to measure and compare the polarographic solvent properties of the anhydrous aliphatic diamines. In fact, there has been no reported instance of the use of anhydrous 1,3-propanediamine or 1,4-butanediamine in any electro- chemical system.
42

Interaction between Icelandic basalt and Swedish granite with Swedish bitumen emulsion : Is it possible to use Swedish bitumen emulsion in Iceland?

Úlfarsdóttir, Björk January 2018 (has links)
Like in any modern civilization, roads in Iceland have an important role in thedaily lives of inhabitants. Consequently, road quality is of equal importance, butIcelandic roads have shown problems when surface dressing is used where itlooks decent after being paved during summer but then deforming pretty rapidlyafter being hit by elements of winter. Roads in Sweden however, do not seem tohave the same problem.The aim of this study is to minimize this road deformation by examining surfacedressing and aggregates. The Icelandic climate is also a factor to this problemsince the humidity is comparatively high, summers are cool, winters are mild andthe climate is overall challenging. Furthermore, winter thaws are distinctivecharacteristic of the Icelandic weather, which increases strain on the asphalt.An experiment was conducted where the adhesion of surface dressing that iscommon in Sweden was tested with two different aggregates by Vialit plateshock test method. First it was tested with Swedish granite and then withIcelandic basalt. The results from the aggregates were compared where theadhesion with the granite was stronger than with the basalt.Previous study have found that by choosing binder and aggregate that have highadhesivity at low temperature reduces the risk of surface dressing defects,especially when paving takes place in the early and late summer season. Whenchoosing aggregates for road construction the main criteria is cost, thereforeaggregates that are used usually reflect the local geology because transportingaggregates for significant distances is expensive. Concluding from theexperiment, it is not recommended to use the basalt with the Swedish surfacedressing in practice now due to the lesser adhesion compared to the granite.However further research on the asphalt mix with the Swedish surface dressingand the basalt should be conducted.
43

Effektivisering av orena lösningsmedelsströmmar på AstraZeneca / Optimization of polluted solvent streams at AstraZeneca

Goralski, Alma, Persson, Kajsa January 2017 (has links)
This project was undertaken at one of AstraZeneca's substance factories in Södertälje, Ersättningsfabriken, EFA. The project aimed to facilitate discharge of different solvent streams from the factory. The manufacture of drugs necessitates the use of large quantities of solvent. This creates  a  huge volume of waste to be disposed of. As waste streams leave one of the units in the factory, they are categorized based on their contents and provided with different article numbers. After  the  waste streams leave the units they are sorted and later destroyed according to their article number. The aim of this project was to map out all those waste streams from EFA that travel via the tank cellar to the storage unit, before destruction/purification. Factors such as amount, time of depletion and the way the waste streams travel to AstraZeneca central unit for waste disposal, were evaluated. At the central unit for waste disposal the solvents are stored in destruction tanks before external or internal destruction/purification. The goal of the project was further to develop a plan to reduce the number of bottlenecks that occur whilst emptying units during production and to increase the efficiency of the emptying process. A number of different methods were employed in order to achieve the project's goals. Practical work and a one week internship in production were combined with interviews,  data  collection  from archives, documents  and the use of different programs. A survey of all the waste streams leaving units in the factory was produced. Furthermore, statistics regarding the load in the tanks in the tank cellar and usage of different articles were compiled. A comparison of the methods of sorting waste and the articles was made between AstraZeneca and the external company that collects the  waste. This comparison  led to a recommendation to eliminate one of the articles, as eliminationwould  enable more efficient  usage of  the tank cellar. / Projektet genomfördes på en av AstraZenecas substansfabriker i Södertälje som heter Ersättningsfabriken, EFA, med syftet att underlätta hanteringen av avfallsströmmar från fabriken. Vid läkemedelstillverkning används stora mängder lösningsmedel vilket leder till att stora mängder avfallsströmmar som måste tas om hand. De olika avfallsströmmarna erhåller ett artikelnummer baserat på dess innehåll då de lämnar en enhet i fabriken och sorteras samt destrueras beroende på detta artikelnummer. Projektets inledande mål var att kartlägga alla avfallsströmmar i fabriken som leds via tankkällaren till lagring innan destruktion/rening. Faktorer som undersöktes var mängd, tömningstid och tömningsväg till AstraZenecas centrala enhet för avfallshantering. Vid den centrala enheten lagras lösningsmedlen i destruktionstankar innan extern eller intern destruktion/rening. Målet med projektet var även att reducera antalet krockar som uppstår vid tömning i produktionen då flera enheter önskar tömmas samtidigt samt att utforma en plan för att effektivisera tömningama för smidigare produktion. För att uppfylla projektets olika mål krävdes ett brett arbetssätt för att inhämta information och data. Praktiskt arbete och praktik i produktionen i EFA har kombinerats med intervjuer och datainsamling från arkiv, dokument samt genom användning av olika datorprogram.
44

Flow Injection and Photometric Determination of S(IV) in Rainwater with Pararosaniline

Hedgecock, Frank A. 01 January 1986 (has links) (PDF)
The photometric pararosaniline (pRA) method for determination of S(IV) has been adapted to flow injection sample processing (FIA). Prominent features of the method include a limit of detection of 0.010 ppm of dissolved sulfur dioxide and a sampling rate of 20 per hour. The concentration range investigated was 0.010 to 0.200 ppm S02. Sequential samples were collected from two rainstorms and SO2 concentrations were measured for 19 samples. The suppression of interference by Cr(III), Mn(II), and Fe(III) using 1,2-cyclohexylenedinitrilotetraacetic acid (CDTA) and ethylenediaminetetraacetic acid (EDTA) was investigated. A comparison of the adapted FIA method and its parent manual method has shown the FIA method to have the advantages of increased sample throughput, decreased reagent consumption, and increased precision.
45

The Use of Scheffe-Equivalent Equations to Predict Physical Properties of Neoprene

Loh, Cheng Y. 01 January 1986 (has links) (PDF)
The goal of this study is to find a more organized and directed approach to build models for mixture systems. An attempt is made to generate and then compare Scheffe (mixture) models with those generated by McGee using the ‘conventional’ method for neoprene data. The models are judged on their ability to predict physical properties of neoprene by comparing the following: predicted and actual values by inspection; the calculated % error of prediction; the squared multiple correlation coefficients; adjusted squared multiple correlation coefficients; the Fisher statistic and significance probability. Scheffe models do not have an intercept term and test statistics which appear on the computer printout are inflated. Pseudocomponents and Scheffe-equivalent models are procedures used to obtain accurate test statistics to describe the selected Scheffe models. The effectiveness of these two procedures is evaluated. Results indicate that Scheffe models are better predictors for the physical properties of neoprene than those generated by McGee using the ‘conventional’ method in 1980. Scheffe-equivalent equations are found to be more reliable than pseudocomponents for generating accurate test statistics to describe the selected Scheffe models.
46

New Synthetic Applications of Enaminoketones

Buck, Timothy J. 01 January 1986 (has links) (PDF)
This report discusses research concerning synthetic applications of enaminoketones. The work may be divided into four parts as follows: a) replacement of the dimethylamino group of certain enaminones by other amine groups through a simple procedure; b) formation of 3-alkyl-pyrazoles; c) formation of 2-amino-4-alkyl-pyrimidines; d) synthesis and subsequent reduction of iminium salts. The starting materials (E-1-(N,N-dimethylamino)-1-alkene-3-ones) have been condensed with hydrazine and guanidine to form pyrazoles and pyrimidines, respectively. The same starting materials have been reacted with POCl3 in CH2Cl2 to produce chlorovinyliminium salts. These have then been reacted in situ with reducing agents to produce chlorovinyl amines. Additionally, the experimental procedures used to produce these products are revealed, and the physical properties of the products are given. Recommendations for future research are made.
47

The Development of Colorimetric Assays to Determine the Identity and Frequency of Specific Nucleobases in DNA Oligomers

Thomas, Elizabeth Marie 01 January 2016 (has links)
Colorimetric methods combined with color-changing chemical probes are widely used as simple yet effective tools for identifying and quantifying a wide variety of molecules in solution. For nucleic acids (DNA and RNA), perhaps the most commonly used colorimetric probe is potassium permanganate, which can be used to identify single-stranded pyrimidines (thymine and cytosine) in polymers. Unfortunately, permanganate is not an effective probe for identifying purines (adenine and guanine), especially in the presence of the more reactive pyrimidines. Therefore, robust methods for discriminating between the purines remain elusive, thereby creating a barrier toward developing more complex colorimetric applications. In this dissertation, we demonstrate that chromophores such as permanganate and bicinchoninic acid (BCA) and copper, however, when combined with nucleobase-specific chemical cleavage reactions, can be a colorimetric probe for the identification and quantification of cytosines, adenines and/or guanines in single-stranded DNA oligomers, even in the presence of thymines. Furthermore, the reactions are stoichiometric, which allows for the quantification of cytosine, adenine and/or guanine frequency in these oligomers. The BCA/copper reagent detects the reducing sugar, 2-deoxyribose, resulting from the chemical cleavage of a given nucleotide’s N-glycosidic bond. Therefore, these colorimetric assays are effectively detecting abasic sites in DNA oligomers, which are known to occur in damaged DNA. Our analytic approach termed colorimetric identification of exposed nucleic acids (CIENA) combines the use of BCA/copper, permanganate, and diphenylamine chromophores along with digital image capture to identify and quantify each nucleobase within DNA. The digital image color properties are quantified in terms of the image’s hue, saturation, and lightness using the CIELAB color space and ΔE quantification of color. CIENA is a simple, low-cost tool that could be applicable in various types of nucleic acid analyses, such as the quantification of nucleobase composition and the identification of damaged DNA.
48

Design of Water Splitting Devices via Molecular Engineering

Li, Fusheng January 2016 (has links)
Converting solar energyto fuels such as hydrogen by the reaction of water splitting is a promising solution for the future sustainable energy systems. The theme of this thesis is to design water splitting devices via molecular engineering; it concerns the studies of both electrochemical-driven and photo-electrochemical driven molecular functional devices for water splitting. The first chapter presents a general introduction about Solar Fuel Conversion. It concerns molecular water splitting catalysts, light harvesting materials and fabrication methods of water splitting devices. The second chapter describes an electrode by immobilizing a molecular water oxidation catalyston carbon nanotubes through the hydrophobic interaction. This fabrication method is corresponding to the question: “How to employ catalysts in functional devices without affecting their performances?” In the third chapter, molecular water oxidation catalysts were successfully immobilized on glassy carbon electrode surface via electrochemical polymerization method. The O-O bond formation pathways of catalysts on electrode surfaces were studied. This kinetic studyis corresponding to the question: “How to get kinetic information of RDS whena catalyst is immobilized on the electrode surface?” Chapter four explores molecular water oxidation catalysts immobilized on dye-sensitized TiO2 electrodeand Fe2O3 semiconductor electrode via different fabrication methods. The reasons of photocurrent decay are discussed and two potential solutions are provided. These studies are corresponding to the question: “How to improvethe stability of photo-electrodes?” Finally, in the last chapter, two novel Pt-free Z-schemed molecular photo-electrochemical cells with both photoactive cathode and photoactive anode for visible light driven water splitting driven were demonstrated. These studies are corresponding to the question: “How to utilizethe concept of Z-schemein photosynthesis to fabricate Pt-free molecular based PEC cells? / <p>QC 20160129</p>
49

Separation of Transition and Heavy Metals Using Stationary Phase Gradients and Chelation Thin Layer Chromatography / Evaluation of the Effectiveness of POGIL-PCL Workshops

Stegall, Stacy L 01 January 2017 (has links)
Gradient surfaces exhibit a variation in functionality along the length of the surface. One method for preparing gradients is controlled-rate infusion (CRI). In Part 1 of this work, CRI was used to prepare gradients for the purpose of separating transition and heavy metals. Initial work on this project was focused on controlling the retention of the metal ions by varying the number of amine groups, aminoalkoxysilane concentration, and the infusion time. The retention factors of four metal ions varied predictably with increasing number of amine groups, increasing aminoalkoxysilane concentration, and increasing infusion time, producing small but useful changes in the retention factors. The continuation of this project involved the preparation of two-dimensional multi-component gradients on TLC plates, which were used to separate six transition and heavy metals. The retention, and thus the separation, was affected by the presence or absence of a gradient and the direction of the gradient. Part 2 of this work focused on understanding the factors that motivated instructors in the early and late stages in the process of change. Instructors who attended the POGIL-PCL (Process-Oriented Guided Inquiry Learning in the Physical Chemistry Laboratory) workshops were asked to complete online surveys. The goals of the first survey were to understand the factors that initially interested instructors in POGIL-PCL, to determine if instructors enter the implementation stage, and to understand the factors that affect how instructors implement POGIL-PCL. Later surveys were designed to explore the development of the POGIL-PCL network and assess whether implementation is sustained over time.
50

Selective Indicators for Optical Determination of Disease Biomarkers

Hakuna, Lovemore 01 December 2014 (has links)
The most abundant biological thiols, homocysteine (Hcy), cysteine (Cys) and glutathione (GSH) have been the subject of intense research due to their association with a wide range of diseases. They play a key role in maintaining the redox status of biological systems. Selective detection methods for these thiols are challenging due to their similar structures and properties. Current commercially available detection methods use separations, fragile and expensive enzymatic or immunogenic materials and complex instrumentation. This has led to a global effort towards developing simple and inexpensive optical probes and indicators selective for specific biological thiols. Highly selective chemical probes and simple methods for detection and potential quantification of Hcy and GSH in their natural biological media have been developed. These indicators and methods are relatively simple and inexpensive for potential application at point of care. The selective detection of Hcy using novel asymmetric viologen chemical probes at room temperature is described as well as the use of commercially available materials under photochemical conditions. These probes respond linearly proportional to increasing Hcy concentrations, potentially enabling the monitoring of Hcy levels in human plasma. Additionally, new methods for the selective determination of GSH in human plasma, as well as its quantification in whole blood deposited on filter paper (dried blood spots), is also presented herein.

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