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Megkoulas, Nikolaos. "Physical properties of single additives and additive mixtures in polyolefins." Thesis, University of Sussex, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410363.
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Liétard, Florian. "Évitabilité de puissances additives en combinatoire des mots." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0259.
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Ce document est principalement consacré à l'étude de l'évitabilité des cubes additifs dans les points fixes de morphismes. Les problèmes d'évitabilité des puissances additives sont connus pour avoir des implications dans la théorie des semi-groupes. Depuis un article publié en 2013 par J. Cassaigne, J.D. Currie, L. Schaeffer et J.O. Shallit, nous savons qu'il est possible de construire sur l'alphabet {0,1,3,4} un mot infini qui évite les cubes additifs, i.e., un mot qui ne contient pas trois facteurs consécutifs de même taille et même somme. Nous commençons par expliquer notre démarche de recherche avec cet article comme point de départ et par discuter des similarités entre les différents morphismes permettant d'éviter les cubes additifs sur des alphabets de 4 lettres. Nous expliciterons la façon dont nous avons programmé en C++ la recherche de morphismes créant des mots infinis sans puissances additives. Nous étendons ensuite la preuve de l'article de 2013 à un ensemble infini de morphismes (correspondant à une classe d'équivalence). Après l'étude d'un exemple nous développons une démonstration basée sur des substitutions entre les morphismes. Le résultat principal de ce document est qu'il est possible de donner, sur chaque alphabet de 4 lettres qui ne soit pas une transformation affine de {0,1,2,3}, un morphisme explicite possédant un point fixe infini sans cubes additifs. Ce travail, effectué en collaboration avec Matthieu Rosenfeld, a donné lieu à la publication d'un article. Pour démontrer ce résultat nous utilisons un argument contenu dans l'article de 2013, des majorations effectuées après disjonction des cas et des arguments de symétries entre les alphabets. Enfin, nous nous intéressons à l'évitabilité des cubes additifs sur {0,1,2,3} afin de tenter de répondre à une question posée en 2018 par M. Rao et M. Rosenfeld. Cet alphabet est le seul de quatre lettres pour lequel notre résultat principal n'apporte pas de réponse. Nous représentons graphiquement les mots possédant des puissances additives et nous développons deux programmes informatiques parallélisés. Le premier permet de détecter efficacement les puissances additives dans un mot très long, le second permet de créer un mot de plus de 70 millions de lettres sans cube additif sur {0,1,2,3}. Nous améliorons ainsi significativement la précédente borne connue (1.4x 10^5). Pour parvenir à ce résultat nous inversons périodiquement l'ordre de priorité pour le choix des lettres dans la construction du mot comme nous le suggéraient les représentations graphiques. Nos programmes utilisent des approches à la fois multi-ordinateurs et multi-threads pour gagner en efficacité<br>The present thesis is dedicated to the various aspects of the problem of avoiding additive cubes in the fixed points of morphisms. Problems concerning the avoidability of additive powers are closely related to questions in the theory of semigroups. Since the publication of the article of J. Cassaigne, J.D. Currie, L. Schaeffer and J.O. Shallit (2013) we know that it is possible to construct an infinite word over {0, 1 ,3, 4} that avoids additive cubes, i.e., a word that avoids three consecutive blocks of same size and same sum. We first explain the methods used by the authors in their article, and then use it as a starting point for our discussions, with the ultimate aim to clarify the various similarities and connections between the different morphisms that allow to avoid additive cubes on alphabets over 4 letters. We next discuss our implementation in C++ of the investigation of theses morphisms, and then proceed to give an infinite family of morphisms (corresponding to classes of equivalence) that avoid additive cubes. After this investigation, we give a general proof scheme that is based on substitutions between morphisms. The main result of the thesis is that for any alphabet of 4 letters, with the sole exception of the alphabet {0, 1 ,2, 3} and its affine transformations, there is an explicit morphism whose infinite fixed point avoids additive cubes over the given alphabet. This work has been carried out in collaboration with Matthieu Rosenfeld and gave rise to an article in a peer-reviewed journal. In order to show this result, we use arguments from the article of Cassaigne et al., several numerical estimates for the underlying quantities, case disjunction as well as symmetry considerations for the alphabets under consideration. In the final part of the thesis we then study the question of avoiding additive cubes over {0, 1 ,2, 3} with the hope to answer a question posed by M. Rao and M. Rosenfeld in 2018. This alphabet is the only 4-letters alphabet where our result does not apply. We first study by graphical means the words that contain additive powers, and we discuss and implement in a second step two parallelized computer programs. The first program detects in an efficient way the occurrence of additive powers in very long words, whereas the second one allows to create long words over {0, 1 ,2, 3} without introducing any additive cube. With the help of these programs, we obtain a word of over 70 million letters that avoids additive cubes over {0, 1 ,2, 3}. This largely improves on the former known bound (1.4 x 10^5). To obtain our result, as suggested by our graphical considerations, we periodically reverse the order of priority for the choice of the letters in the construction of our word. Our programs use multi-computers and multi-threads settings to gain considerably on efficiency
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Oluz, Zehra. "Additives For Photodegradable Polyethylene." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614537/index.pdf.
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Polyethylene (PE) is one of the most popular polymers used in daily life. However, saturated hydrocarbons cannot absorb the energy of light reaching to earth, so degradation process is rather slow which in return cause disposal problems. On the other hand, it was observed that in presence of oxygen and impurities in the polymer matrix, degradation can be rendered to shorter time intervals. This study covers investigation of effect of three different additives in UV induced oxidative degradation of polyethylene.
In this work vanadium (III) acetylacetonate, serpentine and Cloisite 30B were used as additives both together and alone to follow photodegradation of polyethylene. Amount of vanadium (III) acetylacetonate was kept constant at 0.2 wt%, while serpentine and Cloisite 30B were used between 1 and 4 wt%.
All compositions were prepared by using Brabender Torque Rheometer, and shaped as thin films by compression molding. Samples were irradiated by UV light up to 500 hours. Mechanical and spectroscopic measurements were carried out in certain time intervals to monitor the degradation.
It can be concluded that all combinations of three additives showed the fastest degradation behavior compared to pure PE. In the absence of vanadium (III) acetylacetonate the degradation was slowed and fluctuations were observed in the residual percentage strain at break values. There was not a significant change in tensile strength of all samples. Carbonyl index values followed by FTIR were always in increasing manner. Thermal properties were also investigated by DSC Thermograms and they did not change significantly.
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Starkie, Joanna Rachel. "Wax anti-settling additives." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/284911.
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Wax anti-settling additives (WASA) are used to mitigate against the problems caused by the settling of n-alkane wax crystals, which crystallise from petroleum diesel. This can result in the blocking of fuel filters and hence vehicle failure. However, the mode of action for such additives is not currently known and two mechanisms have been proposed: they reduce the wax crystal size to such an extent that they settle very slowly; or they induce gelation in the wax suspension. This project aims to elucidate the mechanism of WASA within the diesel system. A room temperature crystallising model diesel (10 wt% n-alkanes in dodecane) has been developed. This model system has given a good response to the additives, with the wax crystals reduced in size, and is hence suitable for mechanistic studies. Differential scanning calorimetry and infra-red spectroscopy both suggest that the WASA is incorporated in or onto the wax crystal. DSC shows that small amounts of WASA suppress the wax crystallisation temperature and change the shape of the heat flow curve. FT-IR shows the WASA amide stretch present within filtered and dried wax crystals. Intriguingly, electrophoresis experiments show that the WASA imparts a positive charge to the wax crystals, suggesting an electrostatic role in the WASA action. Rheological experiments show the presence of a weak gel in the WASA doped model diesel. However, the gel strength is not altered by the presence of an organic salt and thus cannot be purely electrostatic in origin. Small angle neutron scattering has been conducted to help locate the WASA in the system. It has shown that in solution WASA shows a collapsed polymer coil structure with a single molecule occupying a 28 Å diameter sphere and multiple WASA molecules forming a 2400 Å diameter sphere. In the presence of the wax the WASA scatter does not significantly change suggesting that the WASA is on the surface of the wax crystal. By combining these results, a mechanism of WASA action is proposed as WASA cations interactions bridging between the wax crystals causing a weak bridging flocculation gel with electrostatic and steric effects contributing to stabilisation. The WASA charges are partially dissociated thus giving the electrophoretic effect and the long chains on the cations can contribute to stability via steric stabilisation.
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Jacobs, Joseph Leonard. "Enzyme additives for grass silage." Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329306.
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Rix, K. J. B. "Food additives in acute psychoses." Thesis, University of Aberdeen, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332704.
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Klöden, Burghardt, Alexander Kirchner, Thomas Weißgärber, et al. "Elektronenstrahlschmelzen – ein pulverbettbasiertes additives Fertigungsverfahren." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-215056.
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Aus der Einleitung:
"Das selektive Elektronenstrahlschmelzen (engl. Electron Beam Melting (EBM®)) ist ein pulverbettbasiertes additives Fertigungsverfahren, mit dessen Hilfe metallische Bauteile schichtweise hergestellt werden können. Der schematische Aufbau einer entsprechenden Anlage ist in Abbildung 4 dargestellt. Dabei erfolgt die Strahlerzeugung im Bereich 1 (die Kathode besteht entweder aus Wolfram oder bei den neuesten Systemen aus einkristallinem LaB6). Die Strahlablenkung durch ein elektromagnetisches Linsensystem erfolgt im Bereich 2. Der Bereich 3 ist die eigentliche Baukammer, in der sich unter anderem die Vorratsbehälter für das Pulver, das Rakelsystem sowie die Komponenten des Bauraums (Käfig mit Hitzeschild, Bauplattform mit Startplatte) befinden. ..."
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Niste, Vlad. "WS2 nanoparticles as lubricant additives." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/383967/.
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Due to their excellent tribological properties and potential to replace problematic lubricant additives currently in use, WS2 nanoparticles (NPs) have spurred considerable interest from academia and industry over the last two decades to decipher their mechanism of action. To elucidate the mechanism, this study carried out tribological tests at high pressures and low/high temperatures (40 and 100ºC) and investigated the tribofilm generated on the wear track and its wear and friction properties. It was found that WS2 NPs react with the metal substrate at high temperatures to form a chemical tribofilm covered with squashed NPs. The generation of this tribofilm accounts for their excellent tribological properties. By investigating the chemical and mechanical properties of the tribofilm, it was possible to explain the tribological properties of WS2 NPs. Based on chemical analysis results, a layered structure was proposed for the chemically formed tribofilms. The large amount of tungsten compounds in the composition may explain the excellent mechanical properties of the tribofilm, as revealed by nanoindentation tests. The importance of base oil polarity was investigated. It was found that the efficiency of the NPs is reduced in polar oils, because the oil molecules can compete with the nanoadditive by adsorbing on the metal surface in the tribological contact and impeding the formation of the tribofilm. To investigate which type of WS2 NPs (2H or IF) performs better in tribological applications and if other tungsten dichalcogenides (IF-WSe2) are also potential candidates as nanoadditives, tribological tests and analysis of the wear tracks were performed. 2H-WS2 showed superior friction and wear reducing properties in high-pressure high-temperature contacts. The tribological performance of 2H-WS2 NPs was compared to that of popular conventional additives, e.g. antiwear zinc dialkyldithiophosphates (ZDDPs) and organic friction modifiers (OFMs). At the end of three hour tests, 2H-WS2 NPs and ZDDP+OFM mixtures showed similar antiwear properties, but 2H-WS2 NPs induced a significant reduction of the friction coefficient in the mixed and boundary lubrication regimes. The ability of 2H-WS2 NPs to inhibit hydrogen permeation in high strength bearing steel used in fuel cells and wind turbines was also investigated. Thermal desorption spectroscopy revealed that the chemical tribofilm generated on the wear tracks can significantly reduce the concentration of hydrogen and water in the steel substrate after rolling contact fatigue tests performed in high-temperature high-pressure conditions.
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Kulmatova, Dilafruz. "Turbulent drag reduction by additives." Paris 6, 2013. http://www.theses.fr/2013PA066480.
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The addition of a minute amount of polymer or surfactant additive to a turbulent fluid flow can result in a large reduction in the frictional drag in pipes and channels. Over the past decades, numerous studies have been carried out on drag reducing additives (DRA). DRA have been successfully applied for potential benefits in various industrial processes, including oil well operations, heating and cooling water circuits, marine and biomedical systems. The use of additives to enhance flow in petroleum pipelines has received the greatest attention due to its great commercial success in reducting cost and energy consumption. Although this effect has been known for almost half a century, the detailed mechanism of drag reduction have still not been clearly identified and is still a subject of ongoing controversy. The aim of this thesis is to develop an understanding of the role of drag reducing agents and to explain the nature of drag reduction mechanism. This could have an impact on the design of efficient pumping systems, the design of drag-reducing agent that are more stable over time, and the modeling of mixing processes that could be an important consideration in designing practical systems<br>L'ajout d'une quantité infime d'un polymère ou d'un additif tensioactif à un flux turbulent de fluide peut causer une forte diminution de la friction dans les tuyaux et les canalisations. Ces dix dernières années, de nombreuses études ont été réalisées sur les agents réducteurs de friction (ARF). Les ARF sont utilisés pour leurs effets bénéfiques dans de nombreux procédés industriels, tels que l'extraction de pétrole, le chauffage et le refroidissement de circuits de circulation d'eau ainsi que dans des systèmes marins et biomédicaux. L'utilisation d'additifs pour améliorer l'écoulement dans les canalisations de pétrole a été particulièrement étudiée, en raison de son succès commercial en terme de réductions de couts et de consommation d'énergie. Bien que l'action de ces additifs est connue depuis presque cinquante ans, le mécanisme détaillé de la réduction des frictions n'a pas été clairement identifié et est encore sujet à controverses. Le but de cette étude est d'apporter une explication au rôle de ces agents en matière de réduction des frictions, et d'expliquer la nature ce mécanisme. Les résultats présentés ici peuvent influencer significativement la conception des systèmes de pompes, le développement d'agent réducteurs de friction plus stables ainsi que la modélisation de procédés mixtes qui pourraient devenir une considération majeure dans le design de systèmes réels
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Gonzalez, Christophe. "Utilités additives : existence et construction." Paris 6, 1996. http://www.theses.fr/1996PA066740.
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Les fonctions d'utilités additives sont l'un des moyens les plus efficaces de représenter des préférences multi-attributs. C'est pourquoi la recherche de conditions assurant l'existence de telles fonctions a donné lieu à de nombreux travaux. Malheureusement, les conditions d'élimination, nécessaires à leur existence, sont très difficilement testables en pratique, ce qui a amené les chercheurs du domaine à faire appel à des hypothèses structurelles très restrictives sur toutes les dimensions de l'espace des préférences (solvabilité et connexité), réduisant ainsi leur champ d'application. L'objectif de ce mémoire est de proposer de nouvelles conditions, tout autant testables mais moins restrictives. Une étude des axiomes d'élimination nous a permis de conclure qu'en l'absence d'hypothèses structurelles sur au moins deux dimensions de l'espace des préférences, il ne peut y avoir de conditions testables. Nous avons montré qu'en revanche, celles-ci existent dès lors qu'au moins deux de ces dimensions possèdent des propriétés structurelles. Pour parvenir à ce résultat, nous avons dû nous éloigner des deux approches classiques (algébrique et topologique), et en définir une nouvelle, dite approche analytique. Nous avons illustré ces résultats théoriques par deux exemples ou les résultats classiques ne peuvent être appliqués : (i) une prise de décision collective dans laquelle certains attributs sont solvables et d'autres non ; (ii) un modèle de décision à base de données fréquentistes imprécises. Enfin, nous avons implémenté une application graphique permettant de construire des fonctions d'utilités additives. Le modèle conversationnel développé à cet effet permet de réduire les problèmes d'imprécision et de biais dans les réponses des utilisateurs.
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Золотова, Світлана Григорівна, Светлана Григорьевна Золотова, Svitlana Hryhorivna Zolotova, and I. Yu Matyushenko. "Human's health and food additives." Thesis, Видавництво СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/18198.
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Upadhyay, Mahua. "Polymeric additives for lubricating oil." Thesis, University of North Bengal, 2015. http://ir.nbu.ac.in/handle/123456789/1830.
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Jibbouri, Sattar al. "Effects of additives in solution crystallization." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=967410673.
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Nabeel, Muhammad. "Diffusion of Elemental Additives during Sintering." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-100702.
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The mechanical properties of components made by PM steels are normally inferior to those made by alternative processes. One of the main reasons is that a large amount of pores are present in sintered components. The other main reason is that the alloying elements, particularly Ni, are not uniformly distributed after conventional sintering procedures. This work is aimed at a better understanding of the influence of alloying additions on mechanical properties and homogeneity of the microstructure. The experimental work has been carried out in two trials. Trial 1 was performed to investigate mechanical properties of Distaloy powders (commercial grades) and second trial to examine influence of alloying additions on homogeneity of microstructure. For trial 1, as-sintered and heat treated specimens were produced by mixing commercial powders with two different carbon levels. Whereas, alloying elements were admixed to base iron powder for producing sintered specimens for trial 2. Mechanical properties including dimensional changes, micro-hardness, tensile strength and impact resistance were measured. Distribution of alloying elements was studied using LOM and SEM-EDS analysis. The results obtained show that additions of alloying elements enhance the mechanical properties. Moreover, interaction of C with Cu and Ni as well as interaction between Cu and Ni have a deceive role in determining final properties of the components. The metallographic investigation indicated that major reasons of heterogeneous microstructure are slow diffusion of Ni in Fe matrix and interaction of other alloying elements with Ni. The results of trial 2 showed that addition of Mo and Cu to Ni-containing PM steels improves the distribution of Ni in Fe matrix. Mo results in improved uniformity of microstructure by lowering the chemical potential of carbon. In Ni and Cu containing alloys, the interaction between Ni and Cu is responsible for enhanced distribution of Ni. However, the improved Ni distribution is achieved at the expense of non-uniform distribution of Cu. In Ni-containing PM steels, improved microstructure homogenization can be attained by increasing Ni-Cu interaction, lowering the surface energy of Ni-Cu liquid and decreasing the chemical potential of carbon.
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Higgins, Clare Louise. "Novel dendritic fuel and lubricant additives." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/65944/.
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Oxidation processes have a detrimental effect on hydrocarbon based materials such as fuels, lubricants, polymers and foodstuffs. Antioxidants are known to interrupt oxidation processes by predominantly reacting with radical species. The development of such stabilisers is discussed in Chapter 1. The use of dendritic architectures in antioxidant development is a relatively 'young’ area of research. This unique class of macromolecule consists of a well-defined, branched structure which can potentially bear a high loading of antioxidant under an excellent degree of structural control. Dendritic architectures are the focus of this thesis and Chapter 2 discusses the synthesis of a series of antioxidant functionalised polyester dendrons via the growth of the AB2 monomer bis(MPA). The intention was to provide a high degree of sterically hindered phenolic end groups for enhanced oxidative stabilisation properties in addition to good solubility within a hydrocarbon matrix and good thermal stability with a resistance to volatilisation at high temperatures. It was revealed that these new branched antioxidants provided superior thermal and oxidative stability properties in comparison to the small molecule antioxidants currently used in the industry. Alternative functional core monomers were also investigated in Chapter 3. The functionalisation of glycerol and triethanolamine (TREN) with antioxidant moieties plus solubilising alkyl chains to yield a series of first generation polyester antioxidants is discussed. Once again, superior thermal and oxidative properties were revealed in comparison to the current industry antioxidants Irganox L135 and Irganox L57. The incorporation of a diphenylamine derivative into the same branching unit as the hindered phenol was investigated in Chapter 4 with the aim of targeting synergistic antioxidant properties. Excellent oxidative stabilities were observed, when compared to a 1:1 blend of Irganox L135 and Irganox L57, whereby an impressive 52% increase in oxidation induction time was observed. The enhanced stabilities were attributed to interesting structure-activity relationships from which it was concluded that the close contact of both amine and phenol functionalities was key in accessing improved antioxidant capabilities. A radical scavenging assay was investigated in Chapter 5 with the aim to understand structure-activity relationships of new sterically hindered phenolic antioxidants. It was revealed that complex mechanistic pathways, in addition to solvent effects, limited the use of this assay. Therefore, further refinement of this potentially time-saving spectroscopic assay is required in order to render it usable in fuel and lubricant development.
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Basso, Fernanda Carvalho [UNESP]. "Corn silage inoculated with microbial additives." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/104070.
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000736831.pdf: 864505 bytes, checksum: 2a3d156922ea1b50f9690c217989dbd0 (MD5)<br>Objetivou-se determinar a qualidade da silagem de milho inoculada com aditivos microbianos. Para tanto, foram realizados três experimentos. No primeiro ano, em silos experimentais, foram testados quatro inoculantes que compuseram os seguintes tratamentos: forragem inoculada com Lactobacillus buchneri (LB), Propionibacterium acidipropionici (PA), Bacillus subtilis (BS), Lactobacillus plantarum (LP) e as combinações LBLP, BSLP e PALP, permanecendo uma silagem sem inoculante (Controle). Após 96 dias da ensilagem, a composição químico-bromatologica e a ocorrência de leveduras e fungos filamentosos foram avaliadas. A estabilidade aeróbia foi realizada durante 12 dias. Nos dias 4, 8 e 12 após a abertura, os valores de pH e a dinâmica de fungos foram determinados. No segundo e terceiro ano experimental avaliou-se a qualidade de silagens escolhidas a partir do primeiro ano. No segundo ano, as silagens estudadas foram: controle, LB e LBLP, confeccionadas em silos superfície. Na avaliação de desempenho, digestibilidade dos nutrientes e síntese de proteína microbiana, se utilizou 30 cordeiros mestiços. O estudo de fermentação ruminal foi realizado em seis cordeiros mestiços com cânula ruminal. No terceiro ano, avaliou-se a associação de silagem de milho inoculada a dois níveis de concentrado. Foram confeccionados dois silos trincheiras, sendo um a silagem controle e outro a LB. As dietas foram compostas das respectivas silagens associadas a 40 e 60% de concentrado, totalizando quatro tratamentos. As avaliações nos animais foram semelhantes às realizadas no segundo ano experimental. Os inoculantes afetaram positivamente as características fermentativas e reduziram a parede celular das silagens. A inoculação promoveu alteração na fermentação ruminal, maior fluxo de proteína microbiana e melhor desempenho dos cordeiros alimentados com dietas compostas pelas silagens inoculadas...<br>This study aimed to determine the quality of corn silage inoculated with microbial additives. Therefore, three experiments were carried out. In the first year, in experimental silos, four inoculants that comprised the following treatments were tested: forage inoculated with Lactobacillus buchneri (LB), Propionibacterium acidipropionici (PA), Bacillus subtilis (BS), Lactobacillus plantarum (LP) and combinations LBLP, BSLP and PALP, remaining silage without inoculant (control). After 96 days of ensiling, the chemical composition and the occurrence of yeasts and molds were evaluated. Aerobic stability was performed by 12 days. On days 4, 8 and 12 after opening the pH values and dynamics of yeasts and molds were determined. In the second and third experimental year the quality of silage chosen from the first year were evaluated. In the second year, the silages studied were: control, LB and LBLP, made in stack silos. In the study of performance, nutrient digestibility and microbial protein synthesis, 30 crossbred lambs were used. The trial of rumen fermentation was performed with six crossbred lambs with ruminal cannula. In the third year, we evaluated the association of corn silage inoculated with two levels of concentrate. Two bunker silos were made (control silage and LB). The diets were composed of the respective silages combined with 40 and 60 % concentrate, a total of four treatments. Assessments in animals were similar to those obtained in the second experimental year. The inoculants positively affected fermentation characteristics and reduced cell wall of silages. The inoculation changed ruminal fermentation and, the flow of microbial protein and performance of lambs fed diets containing the inoculated silages were increased. The quality of corn silage was improved by inoculation with microbial additive
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Le, Manquais Katherine. "Combustion enhancing additives for coal firing." Thesis, University of Nottingham, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582090.
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Opportunities exist for effective coal combustion additives that can reduce the carbon content of pulverised fuel ash to below 6%, thereby improving the efficiency of low NOx burners and making the ash saleable for filler/building material applications. However, catalytic performance under pulverised fuel boiler conditions has received relatively little consideration. For the first time, the research set out in this thesis systematically compares the reactivity of catalysed and uncatalysed bituminous coal samples during combustion in a drop tube furnace (DTF) and a thermogravimetric analyser (TGA). All of the inorganic compounds investigated were accordingly found to increase the rate of TGA char oxidation, with certain transition metal halides proving to be extremely successful additives. But these trends did not always translate into analogous carbon burnout improvements on th~ medium-scale DTF. This was due to the inherent variability associated with this experimental setup, the use of physical mixtures for catalyst dispersion and the intrinsic volatility of some of the tested salts. Furthermore several very effective additives on the TGA, the copper halides, seemingly deactivated under the conditions experienced in the DTF, reducing the attained carbon burnouts to levels below those observed with the uncatalysed coal fractions. Complex interactions were subsequently discovered between copper (I) bromide and the coal's mineral matter, implying that a copper-iron association could have been behind this behaviour. In contrast, the thermally labile iron halides were found to be exceptional additives for enhancing DTF carbon burnout, even at temperatures above their predicted boiling points in what could have previously been assumed to be a completely mass transfer controlled reaction regime. The combustion improvements associated with the introduction of iron (Ill) bromide were thus rigorously established and then related to the retention of the additive's cation, as indicated by SEM/EDX and ICP-MS.
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Webb, Oliver A. "Bespoke container molecules for fuel additives." Thesis, University of Surrey, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.606795.
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The findings of the first reported guest centric encapsulation study are presented within. The guests were of interest as petrol and diesel (fuel) additives, with the focus on 2-ethylhexyl nitrate (2-EHN), di-tert-butyl peroxide (DTBP), aniline, N-methylaniline (NMA) and N,Ndimethylaniline CNNDMA). Complexation with 2-EHN and DTBP was achieved with the novel calix[4]arene derivative, 5, 11, 17, 23-tetra-tert-butyl, 25, 27-bis(oxyethylphenylurea), 26, 28-dihydroxycalix[4}arene, CA(III). This was confirmed in solution by the use of NMR techniques. The multi-step procedure to yield a tetrol cavitand. with recent updates to the procedures are fully described. A new carceplex system with aniline encapsulated, carceplex aniline (4, 24- 5,5'- 6,10- 11 , 11'- 12, 16- 17, 17'- 18, 22- 23, 23'- 4', 24'- 6',10'- 12', 16'- 18 ',22' dodecamethylenedioxy, 2, 8, 14,20, 2', 8' ,14', 20'-octapentyl-bis-calix[4]arene aniline) was produced in a pioneering pressure tube encapsulation follwing unsuccessful attempts under reflux conditions. A pyrogallol[4]arene with pentyl pendant group (2, 8, 14, 20-tetrapentylpyrogallol[4]arene) PA(I) was synthesised and successfully employed for self-assembled complex formation with aniline, NMA and NNDMA. These complexes were found to be stable in polar and apolar media at 313 K over a duration of 2 months. The complexes were of stoichiometry 10:1 (aniline: PA(I)), 12:1 (NMA : PA(I)), and 4:1 (NNDMA: PA(l)). Significant variation was observed when complexes were analysed by TGA in air up to 800 °C compared to control. PA(I) . aniline and PA(I) . NMA displayed solubilities in apolar media making them suitable for analysis in test engines as fuel additives. The first report of a (two-step) carcerand synthesised from pyrogallol[4]arene, PA(I) with the introduction of methylene dioxy spanning and bridging groups, yielding the novel carcerand 4,24- 5, 4'.- 6, 5' - 10, 1\ ' - 12, 16- 17, 16'- 18, 17'- 22, 23'- 23, 24' - 6', 10'- 18', 22' dodecamethylenedioxy, 2, 8, 14, 20, 2', 8', 14', 20' -octapentyl-bis-calix[4]arene is also presented.
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Lakay, Francisco Martin. "Fungal enzymes as animal feed additives." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52280.
Full textAbstract:
Thesis (MSc)--Stellenbosch University, 2001.<br>ENGLISH ABSTRACT: The use of fungal enzymes as ruminant feed digestibility enhancers was investigated. Currently,
ruminants may not digest 38 to 80 % of fibrous forages' content. A renewed interest in the potential
of feed enzymes for ruminants was prompted by the high costs of livestock production, together
with the availability of newer enzyme preparations. Direct application of enzyme preparations can
improve in vitro dry matter (DM) and neutral detergent fibre (NDF) degradation, indicating that
direct-fed fibrolytic enzymes may be effective in enhancing in vivo digestion of forages.
Two commercial enzyme products, Fibrozyme and Celluclast, and fungal extracellular
enzyme extracts from Aureobasidium pullulans, Trichoderma reesei, Aspergillus aculeatus, and
Thermomyces lanuginosus were evaluated for enhancing in vitro feed digestibility. Fibrozyme
addition to both wheat straw and lucerne hay did not improve their in vitro digestibilities, even after
a two hour pre-incubation period. The four fungal enzyme extracts did not enhance wheat straw's
digestibility, but marginal increases were evident for lucerne hay. Celluclast addition resulted in
marginal increases in the digestibility of both oat hay and oat silage, with no enhanced effect on
lucerne hay and NaOH-treated wheat straw. No relationship could be found between the level of
enzyme activity and the degree of feed digestion in the in vitro assay.
Enzyme hydrolysis with Celluclast, in the absence of rumen fluid, gave more conclusive
results. All the feed samples tested showed a positive response to Celluclast addition, even the less
digestible feeds, namely sugarcane bagasse and wheat straw.
In vitro results show that the assays were unsuccessful, because almost all of the
experiments conducted showed inconclusive results. Alternative feed evaluation assays, which
include the in vivo, in sacco and in situ methods of analysis, as well as gas production measurement
and in vitro analysis with the DAISyII system, should be evaluated. A more detailed study of feed
digestibility should be motivated by determining which feeds are hydrolysable, their chemical
composition, i.e. how accessible the feeds are, and also evaluation of feed mixtures. The enzyme
supplements also need to be evaluated for optimum temperature and pH, as well as the compilation
of enzyme cocktails.<br>AFRIKAANSE OPSOMMING: Die gebruik van swamensieme om die verteerbaarheid van herkouervoere te verhoog, is ondersoek.
Tussen 38 en 80 % van veselagtige voere se inhoud is tans onverteerbaar. 'n Hernieude
belangstelling in die potensiaal van voerensieme vir herkouers word deur die hoë koste van
veeproduksie, asook die beskikbaarheid van nuwe ensiempreparate gedryf Direkte byvoeging van
ensiempreparate kan die in vitro droëmateriaal (DM) en neutrale onoplosbare vesel (NOV)
vertering verbeter, wat daarop dui dat fibrolitiese ensieme wat direk gevoer word, effektief mag
wees tydens die in vivo vertering van voer.
Twee kommersiële ensiemprodukte, Fibrozyme en Celluclast, en die vier ekstrasellulêre
ensieme van vier swamme, naamlik Aureobasidium pullulans, Trichoderma reesei, Aspergillus
aculeatus, en Thermomyces lanuginosus is vir hul vermoë om die in vitro verteerbaarheid van voere
te verbeter getoets. Byvoeging van Fibrozyme by beide koringstrooi en lusernhooi het geen
verbetering in hulonderskeie in vitro verteerbaarheid tot gevolg gehad nie, selfs nie eens na 'n twee
uur vooraf inkubasieperiode nie. Koringstrooi se verteerbaarheid is nie verbeter deur die byvoeging
van die vier swam-ensiempreparate nie, maar 'n minimale verbetering is wel waargeneem in die
verteerbaarheid van lusernhooi. Byvoeging van Celluclast het 'n minimale verbetering in beide
hawerhooi en hawerkuilvoer se verteerbaarheid tot gevolg gehad, maar geen effek op lusernhooi of
NaOH-behandelde koringstrooi se verteerbaarheid nie. Geen verwantskap is tussen die vlak van
ensiemaktiwiteit en die mate van vertering tydens die in vitro toets gevind nie.
Ensiematiese afbraak met Celluclast, in die afwesigheid van rumenvloeistof, het meer
konkrete resultate gelewer. Al die voermonsters het 'n positiewe respons op die byvoeging van
Celluclast getoon, selfs ook die minder verteerbare voere, nl. suikerrietbagasse en koringstrooi.
In die wyer konteks was die resulate van die in vitro verteringstoetse egter onbeduidend as
gevolg van groot variasie in die metings. Alternatiewe voerontledingstoetse, wat moontlik beter
resultate mag lewer, sluit in in vivo, in sacco en in situ analises, asook die meting van gasproduksie
en in vitro analise met die DAISyII sisteem. 'n Meer uitgebreide studie van voerverteerbaarheid wat
die bepaling van die afbraak van voere, hul chemiese samestelling, met ander woorde
toeganklikheid van voere, en die ondersoek van voermengsels behels, behoort aandag te geniet. Die
ensiemmengsels behoort ook ten opsigte van samestelling, optimum temperatuur en pH ondersoek
teword.
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Basso, Fernanda Carvalho. "Corn silage inoculated with microbial additives /." Jaboticabal, 2013. http://hdl.handle.net/11449/104070.
Full textAbstract:
Orientador: Ricardo Andrade Reis<br>Coorientador: Gustavo Rezende Siqueira<br>Banca: Clóves Cabreira Jobim<br>Banca: Carla Luiza da Silva Ávila<br>Banca: Izabelle Auxiliadora Molina de Almeida Teixeira<br>Banca: Flávio Dutra de Resende<br>Resumo: Objetivou-se determinar a qualidade da silagem de milho inoculada com aditivos microbianos. Para tanto, foram realizados três experimentos. No primeiro ano, em silos experimentais, foram testados quatro inoculantes que compuseram os seguintes tratamentos: forragem inoculada com Lactobacillus buchneri (LB), Propionibacterium acidipropionici (PA), Bacillus subtilis (BS), Lactobacillus plantarum (LP) e as combinações LBLP, BSLP e PALP, permanecendo uma silagem sem inoculante (Controle). Após 96 dias da ensilagem, a composição químico-bromatologica e a ocorrência de leveduras e fungos filamentosos foram avaliadas. A estabilidade aeróbia foi realizada durante 12 dias. Nos dias 4, 8 e 12 após a abertura, os valores de pH e a dinâmica de fungos foram determinados. No segundo e terceiro ano experimental avaliou-se a qualidade de silagens escolhidas a partir do primeiro ano. No segundo ano, as silagens estudadas foram: controle, LB e LBLP, confeccionadas em silos superfície. Na avaliação de desempenho, digestibilidade dos nutrientes e síntese de proteína microbiana, se utilizou 30 cordeiros mestiços. O estudo de fermentação ruminal foi realizado em seis cordeiros mestiços com cânula ruminal. No terceiro ano, avaliou-se a associação de silagem de milho inoculada a dois níveis de concentrado. Foram confeccionados dois silos trincheiras, sendo um a silagem controle e outro a LB. As dietas foram compostas das respectivas silagens associadas a 40 e 60% de concentrado, totalizando quatro tratamentos. As avaliações nos animais foram semelhantes às realizadas no segundo ano experimental. Os inoculantes afetaram positivamente as características fermentativas e reduziram a parede celular das silagens. A inoculação promoveu alteração na fermentação ruminal, maior fluxo de proteína microbiana e melhor desempenho dos cordeiros alimentados com dietas compostas pelas silagens inoculadas ...<br>Abstract: This study aimed to determine the quality of corn silage inoculated with microbial additives. Therefore, three experiments were carried out. In the first year, in experimental silos, four inoculants that comprised the following treatments were tested: forage inoculated with Lactobacillus buchneri (LB), Propionibacterium acidipropionici (PA), Bacillus subtilis (BS), Lactobacillus plantarum (LP) and combinations LBLP, BSLP and PALP, remaining silage without inoculant (control). After 96 days of ensiling, the chemical composition and the occurrence of yeasts and molds were evaluated. Aerobic stability was performed by 12 days. On days 4, 8 and 12 after opening the pH values and dynamics of yeasts and molds were determined. In the second and third experimental year the quality of silage chosen from the first year were evaluated. In the second year, the silages studied were: control, LB and LBLP, made in stack silos. In the study of performance, nutrient digestibility and microbial protein synthesis, 30 crossbred lambs were used. The trial of rumen fermentation was performed with six crossbred lambs with ruminal cannula. In the third year, we evaluated the association of corn silage inoculated with two levels of concentrate. Two bunker silos were made (control silage and LB). The diets were composed of the respective silages combined with 40 and 60 % concentrate, a total of four treatments. Assessments in animals were similar to those obtained in the second experimental year. The inoculants positively affected fermentation characteristics and reduced cell wall of silages. The inoculation changed ruminal fermentation and, the flow of microbial protein and performance of lambs fed diets containing the inoculated silages were increased. The quality of corn silage was improved by inoculation with microbial additive<br>Doutor
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Hirt, Benjamin David. "Impact of Additives on Thermionic Cathodes." Ohio University Honors Tutorial College / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1524832507214002.
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Goonetilleka, M. D. R. J. "Migration of additives from thermoplastic polymers." Thesis, Aston University, 1988. http://publications.aston.ac.uk/9720/.
Full textAbstract:
A homologous series of ultra-violet stabilisers containing 2-hydroxybenzophenone (HBP) moiety as a uv absorbing chromophore with varying alkyl chain lengths and sizes were prepared by known chemical synthesis. The strong absorbance of the HBP chromophore was utilized to evaluate the concentration of these stabilisers in low density polyethylene films and concentration of these stabilisers in low density polyethylene films and in relevant solvents by ultra-violet/visible spectroscopy. Intrinsic diffusion coefficients, equilibrium solubilities, volatilities from LDPE films and volatility of pure stabilisers were studied over a temperature range of 5-100oC. The effects of structure, molecular weight and temperature on the above parameters were investigated and the results were analysed on the basis of theoretical models published in the literature. It has been found that an increase in alkyl chain lengths does not change the diffusion coefficients to a significant level, while attachment of polar or branched alkyl groups change their value considerably. An Arrhenius type of relationship for the temperature dependence of diffusion coefficients seems to be valid only for a narrow temperature range, and therefore extrapolation of data from one temperature to another leads to a considerable error. The evidence showed that increase in additive solubility in the polymer is favoured by lower heat of fusions and melting points of additives. This implies the validity of simple regular solution theory to provide an adequate basis for understanding the solubility of additives in polymers The volubility of stabilisers from low density polyethylene films showed that of an additive from a polymer can be expressed in terms of a first-order kinetic equation. In addition the rate of loss of stabilisers was discussed in relation to its diffusion, solubility and volatility and found that all these factors may contribute to the additive loss, although one may be a rate determining factor. Stabiliser migration from LDPE into various solvents and food simulants was studied at temperatures 5, 23, 40 and 70oC; from the plots of rate of migration versus square root time, characteristic diffusion coefficients were obtained by using the solution of Fick's diffusion equations. It was shown that the rate of migration depends primarily on partition coefficients between solvent and the polymer of the additive and also on the swelling action of the contracting media. Characteristic diffusion coefficients were found to approach to intrinsic values in non swelling solvents, whereas in the case of highly swollen polymer samples, the former may be orders of magnitude greater than the latter.
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DELL'ANNO, MATTEO. "FUNCTIONAL FEED ADDITIVES FOR ANIMAL HEALTH." Doctoral thesis, Università degli Studi di Milano, 2023. https://hdl.handle.net/2434/955511.
Full textAbstract:
World population growth is leading to an increase of the of food from animal origin demand. For the future of the planet and food-production system sustainability some important issues required to be faced. Antimicrobial resistance is one of the most important global concerns cause of thousands of deaths per year and livestock can contribute to the antimicrobial resistance spreading. In livestock, the highest use of antibiotic treatments is recorded in young animals, due to their immature immune system, and the presence of several stress sources that predispose young animals to develop multifactorial diseases, particularly from gastrointestinal origin, that causes important economic losses and antibiotic use. Nutrition is no longer considered as science that only satisfies nutritional requirements but is considered fundamental for its functionality through the supplementation of ingredients and additives which contain bioactive molecules that positively impact on health. Functional feed ingredients and additives possess bioactive characteristics, such as antibacterial and antioxidant activities, capable of contrasting infections and improving animal health or a particular organic function. Preserving intestinal health decreases the incidence of pathologies, optimises digestive processes, and promotes animal performance thus resulting in higher profitability for the farmers. The aim of the following project was to evaluate innovative functional feed additives for animal nutrition, in order to increase animal health, performance and reduce the use of antibiotics in farm animals. The attention was focused on the evaluation of algae, tannins extract, leonardite, tributyrin and probiotics as functional feed additives alternative to antibiotics. For reaching this goal different in vitro, in vivo and ex vivo approaches have been used. In vitro methods allowed to characterize functional feed additives for their antimicrobial and antioxidants effects and cell culture was useful to predict their interaction with the intestinal epithelium. In vivo zootechnical trials were conducted on young animals to assess dietary supplementation of functional additives on growth performance, prevention of gastroenteric disorders, metabolic status and microbiota modulation. Obtained results highlighted that functional additives were characterized by bioactive properties such as antioxidant and antimicrobial effects. Their supplementation showed a plethora of positive impacts including higher zootechnical performance, decreased diarrhoea occurrence, improved health status and microbiota modulation. A combined effect was also assessed in order to evaluate a possible synergistic of different additives. The combination resulted in a positive effect for diarrhoea prevention with a slight modulation for the gut microbial environment. Even if feed additives displayed different bioactivities in vitro, they did not always reveal a boosting effect on growth performance in vivo resulting less evident for farmer perception. However, the reduction of gastrointestinal disorders incidence could be considered the most interesting characteristic of functional feed additives which have shown to possibly reduce pathologies occurrence thus improving farm profitability.
Lastly, due to the needing to decrease animal for experimental purposes an innovative ex vivo intestinal perfusion model was developed in order to study nutrient bioaccessibility for obtaining reliable science-based data in line with the 3R principles.
In conclusion, tested compounds can not substitute the therapeutic treatment of antibiotics. However, the utilization dietary approaches supplementing functional feed additives can significantly contribute for decreasing pathology occurrence, boosting animal health and performance thus the antibiotics use. In line with the One Health principles, antibiotics reduction is a key point for the future sustainable development on the planet. The use of functional feed additives can be considered as interesting alternative to antibiotics due to their ability to prevent multifactorial disorders and thus reducing the antibiotic treatments in livestock farming.
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Das, Moumita. "Organic polymeric additives for lubricating oil." Thesis, University of North Bengal, 2016. http://ir.nbu.ac.in/handle/123456789/2760.
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Ussa, Aldana Paula. "Tungsten disulfide nanoparticles as lubricant additives for the automotive industry." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC001/document.
Full textAbstract:
Les normes environnementales toujours plus sévères associées à une constante augmentation de la demande énergétique rendent nécessaires les actions à entreprendre en vue d’améliorer l’efficacité énergétique. Dans le domaine du transport, responsable à lui seul de plus de la moitié de la consommation des ressources pétrolières, les actions visant à optimiser la consommation énergétique se traduisent par la mise en place de nouvelles technologies hybrides, par un travail sur l’aérodynamisme des véhicules, la conception de pneumatiques plus performants ou bien encore la réduction de la taille des moteurs et des boites de vitesse afin de réduire le poids des véhicules. Cependant, selon le VTT (Centre de recherche technique finlandais), dans les voitures particulières, les pertes par frottement représentent un tiers de la consommation totale de carburant. Plusieurs millions de litres de carburant sont ainsi utilisés dans le monde chaque année pour vaincre les forces de frottement. Pour cette raison la recherche en tribologie dans le domaine de l’automobile s’est plus particulièrement focalisée ces dernières années sur le développement de matériaux à faible coefficient de frottement ainsi que lubrifiants plus performants. Ce travail de thèse a pour objectif d’étudier le potentiel des nanoparticules de dichalcogénures métalliques en tant qu’additifs de lubrification pour applications automobiles dans le but de développer de nouveaux lubrifiants hautement performants. Ces nanoparticules, synthétisées pour la première fois dans les années 90, ont déjà montré des propriétés tribologiques intéressantes lors de tests effectués en laboratoire, en régime de lubrification limite. Toutefois, leur utilisation dans des systèmes mécaniques réels nécessite une meilleure compréhension de leurs performances dans des conditions plus proches de la réalité, à savoir en présence de surfaces rugueuses ainsi qu’en présence d’additifs couramment utilisés dans les lubrifiants industriels. Au cours de ce travail, nous nous sommes focalisés sur des nanoparticules de bisulfures de tungstène produites industriellement. Le contexte industriel de ce travail de thèse ainsi que les bases de la tribologie seront exposés dans un premier chapitre consacré à l’état de l’art. Dans ce même chapitre, une revue bibliographique des propriétés lubrifiantes des nanoparticules de bisulfures métalliques (MoS2, WS2) observées lors d’essais tribologiques effectués en laboratoire sera également présentée. L’influence de certains paramètres tels que les conditions d’essais, l’effet de la température, de la concentration, de la cristallinité sera également présentée dans ce premier chapitre.Les résultats de mon travail de thèse seront présentés à travers deux grandes parties. Dans une première, les caractéristiques morphologiques et chimiques des nanoparticules étudiées seront présentées. Leurs propriétés tribologiques dans l’huile de base en présence de surfaces en acier de différentes rugosités seront discutées. Enfin, leurs performances en présence d’additifs couramment utilisés dans les applications industrielles ont également été étudiées. Tous ces essais ont été réalisés en régime de lubrification limite et à 100°C. Dans une seconde partie, le potentiel des nanoparticules pour une application boîte de vitesses a été exploré. Des essais tribologiques ont été réalisés à la fois dans une huile de base ainsi qu’en présence d’un cocktail d’additifs, tout d’abord à l’échelle du laboratoire puis lors de tests réels effectués avec des boites de vitesses utilisées dans l’automobile. Les résultats montrent que les nanoparticules peuvent être utilisées pour augmenter la durée de vie des engrenages<br>The growing environmental concerns, along with the continuous increase of energy demand, have encouraged research to improve energy efficiency in every technological field. In the transport industry, responsible of more than half of the world’s oil consumption, manufacturers have bet on hybrid fuel technologies, more aerodynamic car profiles, innovative tires and even downsizing of engines and gearboxes to reduce the weight of the vehicles to face the problem. However, according to VTT Technical Research Centre of Finland, in passenger cars one third of fuel consumption is due to friction loss. This means that several millions of liters of fuel are used every year to overcome friction around the world. As a consequence, reduction on the friction losses would have a direct impact in oil consumption. For this reason, research in the tribology field has specially focused in the development of low friction materials and more efficient lubricants. This work investigates the potential of metal dichalcogenide nanoparticles as lubricant additives for automobile applications with the aim of formulating more efficient lubricants. These nanoparticles which were synthetized for the first time in the 90’s have shown interesting tribological properties when added to base oil under specific laboratory test conditions. However, their future use in real-life mechanical systems needs a better comprehension of their behavior on rough surfaces and in the presence of additives commonly used in industrial lubricants.Industrially produced tungsten disulfide nanoparticles were used in this work. First of all, the industrial context of this work and the basis of tribology science in general and of tribology in the automotive industry in particular are exposed in the state of the art part. In this section, a literature review of the lubricating properties of laboratory scale produced metal dichalcogenides nanoparticles of tungsten and molybdenum disulfide is exposed. The effect of different conditions (temperature, concentration in oil, contact pressure, among others) is also presented in this first section. The research work done for this thesis is divided in two main parts. In the first one, the nanoparticles were first morphologically and chemically characterized and their tribological potential in base oil was investigated on smooth and rough surfaces under different test conditions. Then, their tribological behavior in the presence of additives that are commonly used in industrial applications, in the boundary lubrication regime and at 100°C was studied.In the second part, the use of nanoparticles for a gearbox application was explored. The potential of the nanoparticles in base oil and in the presence of a commercial package of additives for this application was studied, first at the laboratory scale, and then in scaled-up tests with gearboxes used in cars. The results suggest that nanoparticles can be used to increase life span of the mechanical parts of gears
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Kilinc, Mert. "Production And Characterization Of Boron-based Additives And The Effect Of Flame Retardant Additives On Pet-based Composites." Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610635/index.pdf.
Full textAbstract:
For the aim of production of poly(ethylene terephthalate), PET based flame retardant composites<br>boron based flame retardant additives, 3.5 mole hydrated zinc borate and boron phosphate were synthesized. Zinc borate was synthesized with the reaction of boric acid and zinc oxide in both laboratory and pilot scale reactors. Effects of reaction parameters on kinetics of reaction and final product particle size were evaluated. Boron phosphate was synthesized via dry, wet and microwave methods. In addition to the synthesized flame retardant additives, several non-halogenated flame retardant additives, which were commercially available, were also used. Composites were prepared using twin screw extruder and molded by injection molding, followed by characterization in terms of flame retardancy behavior, mechanical and thermal properties, and morphologies. Based on the results of first stage experiments, aiming to determine effective additives, different amounts and combinations of triphenyl phosphate, triphenyl phosphine oxide, zinc borate and microwave produced boron phosphate were chosen and used in PET matrix. Flame retardancy of the composites were determined by conducting horizontal burning rate and limiting oxygen index (LOI) tests. Smoke emissions during fire were also measured. According to the LOI test results, LOI of neat PET was determined as 21%, and with the addition of 5% boron phosphate and 5% triphenyl phosphate together, LOI was increased up to 36%. The smoke density analysis results implied that, boron phosphate was a successful smoke suppressant for PET matrix. In addition to flammability properties, tensile and impact properties of the composites were also improved with flame retardant additives and expecially with the addition of triphenyl phosphate.
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Barnett, G. M. (Gordon M. ). "Feed additives and animal waste phosphorous reactions." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41322.
Full textAbstract:
Organic phosphorus (P$ sb{ rm o}$) in farm animal wastes must be mineralized to inorganic P for subsequent plant use. This study was conducted to determine if feed additives affect P$ sb{ rm o}$ mineralization, manure decomposition, and plant growth. Feed additives in aqueous systems affected the P mineralization of inositol hexaphosphate by phytase and of adenosine monophosphate by alkaline phosphatase. Pronounced effects were produced by bacitracin and both enzymes and by neomycin on phytase. Feed additives in dairy cattle (Bos taurus L.) manure produced effects on microbial activity as measured by gas production that differed from those produced on fecal phosphatase activity. Additives applied directly or with manure to Ste. Rosalie clay, Greensboro loam, or silica sand had no effect on barley (Hordeum vulgare L.) yield but did produce additive, rate, growth medium, and manure dependent effects on plant P concentration and soil phosphatase activity. Therefore, each feed additive must be independently evaluated to determine its effect on biological systems.
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Sherburn, Richard. "The microbial catabolism of metalworking fluid additives." Thesis, University of Hull, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301630.
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Sellarajah, Shane. "Chiral additives in the asymmetric Heck reaction." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390653.
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McCory, Daniel Francis. "Evaluation and development of livestock slurry additives." Thesis, University of Exeter, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275906.
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Vengudusamy, Balasubramaniam. "Behaviour of lubricant additives on DLC coatings." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/11734.
Full textAbstract:
Non-ferrous surfaces such as diamond-like carbon (DLC) coatings are becoming potential candidates for automotive engine parts because of fuel economy gains that these surfaces offer by operating with very low friction. In recent years, a wide range of DLC coatings have been developed and it is important to understand their film-forming, friction reduction and wear resistance mechanisms under lubricated conditions. This aim of the work described in this thesis is to improve our understanding of the tribological behaviour of DLC coatings with different engine oil additives. The main focus of the thesis is to study a wide range of available DLC coating types with currently available and widely-used additives such as ZDDP, friction modifiers, MoDTC etc., in order to establish general rules of their tribological behaviour that will help lubricant manufacturers produce new oil formulations. The research shows that tribofilms are formed on all DLCs by most of the currently used additives and that the film thickness depends on various factors such as type of DLC coating, doping elements present in the coatings, concentration of hydrogen and tungsten present in the coatings and the counterpart. Hydrogen-free coatings (a-C and ta-C) give lower boundary friction compared to the other coatings whereas hydrogenated amorphous carbon (a-C:H) coatings give better wear resistance properties. Study of a-C:H:W coatings shows that the concentration of tungsten present in the coatings has a significant influence on wear resistance properties but negligible influence on the friction properties when additives are present. The steel/steel couple is known to form a thick ZDDP tribofilm. If one of the contact surfaces is coated with DLC, the tribofilm forming properties on the steel vary and, for some cases, the low boundary friction properties of DLCs are degraded.
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Momeni, Matin. "Adsorption of fuel additives on metal surfaces." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=201933.
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Santo, Celmiro Lázaro Sebastião Espirito. "Validation of alternative additives for paste production." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10237.
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Dissertation presented to confer Master Degree in Chemical and Biochemical Engineering<br>This Dissertation is the result of an internship at the factory of the Group Exide
Technologies located in Castanheira do Ribatejo - Portugal, the world leader in
Battery Productions. The subject is in context of continuous improvement,
reengineering of the process to meet green VRLA - Valve Regulator Lead Acid Battery productions.
Initially, a brief description was made about the technology and productions of Lead-
Acid Batteries at a normal productions. Then, started the executions of Experimental
Productions related to the following case studies:
1. Replacement of expander Vanisperse A by a expander Vanisperse HT-1 used in negative paste. This research was conducted in order to find an alternative additive to replace Vanisperse A and reduce overhead cost. The development of this experimental productions was made by producing negative plates with expander Vanisperse A as normal production and other negative plates with expander Vanisperse HT-1 as an experimental productions considering the concentration of 1.8% , 2.1% and 2.3% being four samples in three types of battery, then performed chemical and electric test of both version for comparison. Conducted performance test, daily discharge, and retention for C10 cycles and C0.25. It was not possible to draw any conclusion since the values does not comply the nominal specifications.
2. Elimination of Boric Acid in GroE dry negative plates to follow the mindset of
continuous improvement and reengineering of the process for green productions of GroE Cells due to environment purposes and related to article 33 of REACH. By ECHA - European Chemical Agency norms and legislations boric acid may have restriction in near future regarding the SVHC issues.
Therefore to prevent it, Exide Technologies is looking forward to find another alternative additive to be used in impregnations of dry negative plates as an
inhibitor of plates oxidations, thus managed to replace it by new additive the
”Baysilone”. In experimental productions for impregnations of plates in GroE Cells following the industrial, electrics tests. The results was outstanding regarding the performance test run on 3 batteries treated with baysilone compared to other 3 batteries treated with boric acid and consequentely, today Castanheira de Ribatejo facilities has altered the process to baysilone additive. 3. Carbon based additives in negatives plates applied in HEV-Hybrid Electric
Vehicles. This OPE-Experimental Productions Order was performed along with battery experts from Exide Technologies – USA. Over one hand the pasting for normal productions was done using the facilities, making sure
that the plates was meticulously selected with no empty pellets as well as the size. By another hand, the pasting for experimental productions was hand pasted using HSAG-High Surface Area Graphite, Printex, ABG and Sphere by which the plates thickness and weights has been always scrupulously checked before curing.The experimental productions was conducted with several separator in order to define the best outcome that follow the clients
specifications. The batteries were sent to investigation laboratory in Exide Technologies – USA as well as to C.L.E.P.C – Central Laboratory of Electrochemical Power and Source at Bulgarian Academy of Science for further tests. The performance test run in Lisbon did not meet our specifications in order to draw any conclusions.
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Chattopadhyay, Devamita. "Studies on protective additives in cell culture /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487861796818776.
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Graf, Marcel, Sebastian Härtel, and André Hälsig. "Numerische Auslegung des Mehrlagenschweißens als additives Fertigungsverfahren." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-225946.
Full textAbstract:
Die additiven Fertigungstechnologien erleben seit einigen Jahren einen enormen Zuspruch bei der Herstellung von Einzelteilserien mit komplexen, endkonturnahen Geometrien und der Verarbeitung von Sonder- oder hybriden Werkstoffen. Prinzipiell lassen sich die Verfahren gemäß VDI- Richtlinie 3404 in drahtbasierte und pulverbasierte unterteilen. Eine weitere Unterteilung erfolgt hinsichtlich der Ausschmelztechnologie. Allen Verfahren ist gleich, dass schichtweise der Grundwerkstoff an den Stellen aufgetragen wird, wo er gemäß Endkontur benötigt wird. Damit ist ein immer wiederkehrender Wärmeeintrag verbunden, der somit Einfluss auf die Mikrostruktur der Bauteile und gleichzeitig auch auf die mechanischen Endeigenschaften ausübt. Die so erzeugten Komponenten sollten wenig Verzug oder Eigenspannungen als auch keine Porosität aufweisen, um die Gebrauchseigenschaften nicht negativ zu beeinflussen. Das Ziel ist es mittlerweile, diese verschiedenen Technologien numerisch abzubilden, um die Bauteileigenschaften vorherzusagen und ggf. Optimierungspotenziale zu eruieren.
Der untersuchte Prozess ist das drahtbasierte Mehrlagenschweißen mittels des Metallschutzgasschweißens, bei dem neben der Simulation auch die Validierung im Fokus hinsichtlich Geometrie und Gefügeausbildung in den Schweißlagen stand. Diesbezüglich wurden im vorliegenden Fall zum einen alle, für die numerische Simulation notwendigen Materialparameter (mechanische und thermophysikalische Kenngrößen) des Schweißzusatzwerkstoffes G4Si1 bestimmt und in ein kommerzielles FEM-Programm (MSC Marc Mentat) implementiert. Zum anderen erfolgt zukünftig die wissenschaftliche Analyse der Verbesserung der Bauteileigenschaft, in dem die Schweißnaht unter Ausnutzung der Schweißhitze warmumgeformt wird. Erste Ergebnisse numerischer Simulationsergebnisse zeigen positive Effekte. Diese zeigen mikrostrukturelle Veränderungen (Kornfeinung durch Rekristallisation) und führten letztendlich zur Steigerung der mechanischen Eigenschaften. Der Vorteil dieser Verfahrenskombination ist außerdem die Kompensation des Verzuges durch die gezielte Umformung und einem gleichzeitigen „Richten“.
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Matović, Branko. "Low temperature sintering additives for silicon nitride." [S.l. : s.n.], 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10806387.
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Wang, Guangyao (Sam), Shawna Loper, Kurt Nolte, and Mike Ottman. "Guidelines for Using Non-Traditional Soil Additives." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2012. http://hdl.handle.net/10150/246074.
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Sheth, Nishant Mukeshkumar. "Evaluation of selected warm mix asphalt additives." Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/601.
Full textAbstract:
Warm mix asphalt (WMA) is an emerging technology that can allow asphalt to be produced and compacted at a significantly lower temperature. In the past, a number of researchers evaluated various WMA mixtures using select testing procedures in the laboratory. However, none of them evaluated all four major WMA products and compared them against both control HMA and WMA mixtures without an additive using a comprehensive set of testing protocols. This thesis presents a comprehensive evaluation result of four major WMA additives regarding their tensile strength, moisture sensitivity, dynamic modulus and flow number.
The WMA specimens exhibited similar air voids as HMA specimens which indicate that WMA additives are effective in compacting asphalt mixtures at a lower temperature. The indirect tensile strengths and tensile strength ratio (TSR) values of all WMA specimens were lower than that of HMA specimens. This result indicates that WMA mixtures could be susceptible to moisture damage. The only WMA mixture with CECABSE RT® exhibited the higher dynamic modulus at 37.8°C than the control HMA mixture. All WMA specimens, except Advera WMA and CECABASE RT®, passed the requirement of 10,000 cycles of repeated loading. Particularly, the WMA mixture with granular Aspha-min® exhibited the lowest permanent deformation followed by the control HMA mixture.
The nano-scale images of additives with asphalt were also taken to study the characterization and interaction of WMA additives with asphalt. A shape resembling bee was observed in all asphalt images which has been criticized by the researchers. However, bee structures were disappeared in those images of asphalt with CECABASE RT® additive. At nano-scale, height and phase angle of all additive were found greater than the asphalt which proves them highly viscous than the asphalt.
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Nouman, Micheal. "Effet de l'exsudation des additifs sur les propriétés d'usage d'un dispositif médical implantable (cathéter)." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS056/document.
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L'état de surface est l'un des paramètres les plus importants pour déterminer la biocompatibilité d'un dispositif médical implantable, tout changement à la surface une fois en contact avec les tissus corporels peut avoir un impact sur la réponse biologique (cytotoxicité, inflammation, irritation, thrombose ... etc.). Pendant le stockage, l’exsudation des additifs peut se produire à la surface des polymères et modifier leurs propriétés. Dans cette étude, nous utilisons du polyuréthane à base de cathéter (Pellethane®), en raison de ses nombreuses applications dans le domaine des dispositifs médicaux, pour évaluer l'impact d’exsudation des additifs sur la biocompatibilité. L'impact des traitements de stérilisation et d'oxydation sur le phénomène d’exsudation a été étudié. L'étude a été réalisée sur du polyuréthane utilisé dans la fabrication de cathéters sur lesquels l’exsudation de cristaux d’additifs a déjà été observée. La stérilisation par rayonnements ionisants (bêta, gamma) a été réalisée sur ce matériau et les échantillons ont été soumis à différents types de processus d'oxydation (UV, H2O2 et action des macrophages). La viabilité des cellules endothéliales a été étudiée. Une évaluation préliminaire de l'hémocompatibilité a été réalisée par la mesure de l'hémolyse du sang total, ainsi que par l'adhésion des plaquettes en contact avec les différents échantillons de PU. L'étude de la production pro-inflammatoire d'IL-alpha; et de TNF-alpha; par des macrophages en contact avec des échantillons a également été rapportée<br>Surface state is one of the most important parameter determining the biocompatibility of animplantable medical device, any change on the surface once in contact with body tissues canimpact the biological response (Cytotoxicity, inflammation, irritation, thrombosis …etc). During storage, the blooming of additives may occur on the surface of polymers and modify their properties. In this study, we use (Pellethane®) catheter-based polyurethane, because of its many applications in the field of medical devices, to evaluate the impact of additives blooming on the biocompatibility. The impact of sterilizing and oxidation treatments on blooming was studied. The study was realized on polyurethane used in the fabrication of catheters on which the blooming of antioxidant crystals has been previously observed. Sterilization by ionizing radiations (beta, gamma) was performed on this material and samples were submitted to different kinds of oxidation process (UV, H2O2 and macrophages action). Endothelial cells viability was studied. A preliminary haemocompatibility evaluation was performed through the measurement of whole blood hemolysis, as well as platelet adhesion in contact with the different PU samples. The study of the pro-inflammatory IL-alpha; and TNF-alpha; production by macrophages in contact with samplesis also reported
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García, Manzanilla Edgar. "Evaluation of in-feed additives in early-weaned pigs: Study of the XTRACT(TM), a plant extracts based additive." Doctoral thesis, Universitat Autònoma de Barcelona, 2005. http://hdl.handle.net/10803/5665.
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El principal objectiu d'aquest treball es avaluar els efectes d'un additiu comercial XT (5% carvacrol, 3% cinamaldehide, 2% oleoresina d capsicum) sobre els rendiments productius i diferents paràmetres de la fisiologia digestiva del garrí deslletat precoçment. Un altre objectiu d'aquest treball es avaluar les possibles interaccions del XT amb altres ingredients, nutrients i additius de la dieta. Aquest treball s'ha d'entendre com a part d'un ampli pla de recerca multicentric organitzat per la companyia Pancosma. <br/>En concret hem avaluat i) l'efecte del XT als paràmetres mencionats depenent del nivell i font de proteïna, ii) la possible interacció entre l'XT i l'àcid fòrmic, i la comparació de l'efecte del XT amb l'acció de l'avilamicina i el butirat sòdic. Finalment, després de tres anys de col·laboració i donat l'interès de la companyia en desenvolupar nous productes basats en extractes de plantes, hem desenvolupat un mètode in vitro per testar el poder antimicrobià d'un ampli ventall de substàncies derivades de plantes. Al treball in vitro, el nostre objectiu ha sigut desenvolupar un mètode molt simple però realista, utilitzant el contingut de diferent trams del tracte intestinal, obtingut dels porcs sense cap modificació, i incubant-lo curts períodes de temps.<br/>Resultats productius<br/>Els resultats productius són molt variables entre experiments. Aquestes variacions són degudes probablement a l'ús de diferent instal·lacions, edats i estats de salut dels animals i la diferent composició de les dietes bassals.<br/>Mesures fisiològiques i físiques<br/>La digestibilitat ileal i rectal i el pH en les diferents part del tracte gastrointestinal s'han estudiat de manera sistemàtica a les tres proves in vivo però no s'han obtingut resultats consistents. Tanmateix, la inclusió de extractes de plantes a la segona prova va provocar un alentiment del buidament gàstric realcionat amb un augment del pH de l'estomac.<br/>Poblacions microbianes <br/>El resultat més consistent de tots els obtinguts es l'augment de lactobacillus amb la inclusió del XT a les dietes. Malauradament, la rellevància d'aquest augment no està gens clara perquè no va tenir relació directa amb cap benefici productiu. <br/>La inclusió del XT ha afectat també altres paràmetres microbians: la concentració de bases púriques i els perfils d'àcids grassos volàtils. Aquest resultats no són molt consistents i de vegades contraris.<br/>Paràmetres epitelials<br/>S'han estudiat els efectes del XT a l'estructura epitelial però una vegada més els resultats són molt variables depenent de la prova. De totes maneres queda clar que l'XT exerceix una gran influencia sobre certs paràmetres immunes del epiteli, i s'han de continuar investigant amb tècniques més especifiques.<br/>Estudis in vitro<br/>El mètode in vitro s'ha utilitzat amb èxit pe compara diferents additius. Les variacions de fermentació in vitro no només depenen del additiu utilitzat, sinó també de l'edat de l'animal i de la part del tracte gastrointestinal utilitzada d'on s'obté l'inocul. Aquestes variacions s'han d'analitzar amb deteniment.<br/>D'aquests estudis podem concloure que les dosis comercials de XT no presenten efectes antimicrobians directes sobre les poblacions microbianes estudiades (lactobacillus i enterobacterias). Utilitzant el contingut de jejú com inocul, es necessiten dosis properes a 10000 ppm per obtenir efectes antimicrobians. D'altre banda, amb dosis més baixes de les substàncies pures s'aconsegueixen efectes similars. Aquestes dosis varien entre 500 i 3000 ppm de carvacrol i cinamaldehid, depenent de la part del tracte gastrointestinal estudiada. Amb tots els productes, la dosis mínima necessària per inhibir la fermentació es sempre menor amb el contingut del jejú.<br>The main objective of this PhD dissertation is to evaluate the effects of the commercial additive XT (5% carvacrol, 3% cinnamaldehyde, 2% capsicum oleoresin) on productive performance and on different parameters of normal digestive physiology of the early weaned pig: digestibility, pH, epithelial structure, bacterial populations and metabolic activity. It is also an objective of this work to evaluate possible interactions of XT with other ingredients, nutrients and additives included in the diet. This work must be understood in a broader multi-centric research plan organized by the company Pancosma. <br/>In particular, the experiments here presented evaluate i) the effects of XT on the above mentioned parameters depending on the CP level and source, ii) the possible interaction between XT and formic acid, and finally the comparison of the effects of XT with the action of avylamycin and butyrate. After three years of collaboration and given the interest of the company in developing new products based on plant extracts, we developed an in vitro methodology to test the antimicrobial effects of a wide range of plant derived substances. Concerning the in vitro method, our objective was to develop a very simple but realistic method able to obtain significant results, using crude intestinal content obtained from the pigs and incubating it for short periods.<br/>Productive performance<br/>The performance results were very variable among the experiments. These variations were probably due to the use of different facilities, age and health status of the animals and the different composition of the basal diets.<br/>Physiologic and physical parameters<br/>Ileal and whole tract digestibility and pH measurements in different parts of the gastrointestinal tract were systematically studied in the three in vivo trials but no consistent effects of including plant extracts were found. However, plant extracts inclusion in the diet in the second trial resulted in a decrease of gastric emptying rate and an increase of pH. <br/>Microbial populations <br/>The most consistent result in the three experiments was an increase in lactobacilli counts with the inclusion of XT in the diets. However, the relevance of this higher intestinal lactobacilli content is not clear, since there was no direct relation with productive benefits. <br/>XT inclusion also had an effect on other microbial parameters: purine bases concentration and VFA profile. However, those results were not very consistent and often were highly controversial.<br/>Epithelial parameters <br/>The effects of XT on the epithelial structure were studied and, once more, the results were very variable depending on the trial. However, a high influence of XT was found on some immune parameters measured in the epithelium and in the lamina propia, results that encourage continuing investigating these effects with more specific techniques.<br/>In vitro studies <br/>The in vitro method was successfully used to compare different additives. Variations in in vitro fermentation were found not only depending on the additive used but on the age of the animal and on the gastrointestinal tract part used as source of the inoculum. These variations should be studied in more detail in the future.<br/>From these studies, we can conclude that the recommended commercial dose of XT presents no direct antimicrobial effect on the studied populations (lactobacilli and enterobacteria). Doses of near to 10000 ppm are needed to obtain antimicrobial effects in jejunum content. However, lower doses were needed when the pure substances instead of the XT mixture were used. These doses were between 500 and 3000 ppm for carvacrol and cinnamaldehyde, depending on the gastrointestinal tract part studied. The minimum dose of all studied substances to produce antimicrobial effects was always lower for the jejunum than for stomach or cecum content.
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Thomas, Terry Howard. "The effects of motor oil additives on contact potential difference." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17081.
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Maiorino, Lori Ann. "Enhanced infrared absorptance of polyethylene terephthalate via inorganic particulate additives." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19906.
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Erastova, Valentina. "Molecular simulation studies of diesel and diesel additives." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/6361/.
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As diesel fuel is cooled down, waxes are deposited, which are made up from crystals of long chain n-alkanes. Wax depositions are undesirable, since they can block anything from filters in diesel engines to pipelines. It is already known that wax formation can be inhibited by the addition of wax crystal modifiers to diesel fuel. This thesis em- ploys computational models at atomistic and coarse-grained levels to investigate the crystallisation of diesel fuel and the effect of additives upon the crystallisation process. In the first results section, a model for diesel fuel is introduced and a strategy for investigating its crystallisation is developed. Crystallisation was observed from pure n-tricosane, binary and tertiary mixtures of paraffins of similar chain lengths. These systems were found to crystallise into hexagonally arranged lamellae. The presence of different length alkanes was found to create gauche disorders, leading to the formation of lamellar layers with softer edges. It was also found that crystal growth could be simulated more efficiently in the presence of a positionally restrained crystal, acting as a nucleation centre. Subsequently, crystallisation of paraffins, and the solvent effect upon it, was studied. This allowed to establish behavioural trends characteristic for aromatic and aliphatic solvents. Finally, paraffin crystallisation in the presence of four common additives was investigated. A common mode of action for these additives was identified, based upon partial co-crystallisation of additive alkyl chains and paraffin molecules. The main drawback of atomistic simulation is the computational cost, which limits both the time and length scales accessible on modern computers. In order to overcome these inherent limitations, a coarse grained model was developed for a range of n-alkanes. Remarkably, the model shows transferability over 120 K, preserving thermodynamic and structural properties of both melt and crystal. In summary, this thesis provides a detailed picture of diesel crystallisation at a molecular level, and provides new insights into the mechanism of action of a number of common diesel additives.
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Lele, Stephen, and slele@bigpond net au. "Additives on the Curing of Phenolic Novolak Composites." RMIT University. Applied Sciences, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070205.095402.
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The research programme studied the cure reaction of a phenolic novolak resin and the effects of various additives and fillers on the reaction. The programme utilised the recently developed thermal analysis technique of temperature-modulated differential scanning calorimetry (TMDSC) performed in conjunction with other available thermal analysis techniques. TMDSC enables the signal for the heat of reaction to be separated from the underlying specific heat change in the resin. This meant that the reaction could be studied without interference from any physical changes in the resin. The manufacture of composite brake materials required the use of numerous additives and fillers to produce the desired properties. The influence of such additives on the cure rate and final properties of the resin was known to occur but had not previously been measured due to the difficulties presented by the presence of opaque additives. Some additives also underwent thermally induced physical changes in the temperature range of the cure. The final properties and the processing of new brake materials undergoing development often required trial and error adjustments to compensate for changes in cure rate. An understanding of the influence of additives would enable more rapid commercial development of brake materials through an improvement in the ability to predict both the properties of the product and the optimal processing parameters. Processing efficiency could also be improved through detailed knowledge of the kinetics. Moulding cycle times and post-baking times and temperatures were longer than necessary in order to ensure adequate cure at the end of each stage because of the lack of kinetic data. The cure of phenolic resin has been shown to be highly complicated with numerous alternate and competing reactions. For the manufacture of composite materials, knowledge of the kinetic parameters of individual reactions is not considered to be important; rather the overall kinetic parameters are required for prediction. Therefore the kinetic model parameters that best described the observed behaviour were chosen even though the model had no basis in the molecular interaction theory of reaction. Rather it served as a convenient tool for predictions. Characterisation of the resin proved to be difficult due to the presence of overlapping peaks, and volatile reaction products. TMDSC was successfully used to determine the reaction kinetics of the pure resin and the influence of certain additives on the reaction kinetics. The determination of the kinetic parameters using TMDSC agreed well with the traditional Differential Scanning Calorimetry isothermal and non-isothermal techniques. Both the Perkin-Elmer and TA Instruments were utilised for the research and were found to provide reasonably good agreement with each other. The capabilities and limitations of the individual instruments were critically examined, frequently beyond the manufacturers' specifications. TMDSC suffers from a limitation in the heating rate of the sample compared to DSC. However, it was observed that valuable information could still be obtained from TMDSC despite using heating rates that were higher than specified by manufacturers. Hot Stage Microscopy and thermogravimetry were additional experimental techniques used to aid in the characterisation of the resin. Some inhomogeneity of the resin was identified as well as differences in the behaviour of the cure between open (constant pressure) and closed (constant volume) environments were observed. A novel method of determining the orders of the cure reactions and their kinetic parameters was utilised. Reaction models for the overall cure reactions were postulated and tested by fitment to sections of experimental data in temperature regions which appeared to be free of interference from overlapping peaks. Once an individual peak was reasonably well modelled, adjacent overlapping peaks were able to be modelled both individually and in combinations by fitment to experimental data. The Solver function in Microsoft Excel was utilised to find the best fitting model parameters for the experimental data. The model parameters were able to be refined as overlapping peaks were progressively incorporated into the calculations. This method produced results that agreed well with the traditional method of analysing reaction peak temperatures at multiple scanning rates. Model fitment was shown to be of benefit where overlapping reactions occur. Various model scenarios could be tested and optimised to particular sections of experimental data. This enabled the researcher to easily identify areas of possible anomalies and postulate alternative scenarios. The accuracy of the postulated model was able to be determined by its successful fitment to experimental data from experiments run under different conditions.
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Keech, Gregory Wade. "The impact of paper additives on activated sludge." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29380.pdf.
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Verhagen, Franciscus Johannes Josephus. "Toxicology of the food additives BHA and BHT." Maastricht : Maastricht : Universitaire Pers Maastricht ; University Library, Maastricht University [Host], 1989. http://arno.unimaas.nl/show.cgi?fid=5479.
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Grabowski, Daniel W. "Drag reduction in pipe flows with polymer additives /." Online version of thesis, 1990. http://hdl.handle.net/1850/10599.
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Ceylan, Muhammet. "Superhydrophobic behavior of electrospun nanofibers with variable additives." Thesis, Wichita State University, 2009. http://hdl.handle.net/10057/2535.
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This report presents the hydrophobic (90<Ѳ<150) and superhydrophobic (150<Ѳ<180) behaviors of electrospun fibers in the presence and absence of various inclusions. The research on superhydrohobicity has accelerated around the globe and many researchers have been taking keen interests in fabrication of superhydrophobic materials, using several methods, such as sol-gel, vapor deposition, plasma treatment, surface etching and layer by layer assembly. In the present research, polystyrene (PS) and polyvinyl chloride (PVC) fibers with diameters between 200 nm and 7.60 µm were fabricated by electrospinning technique, and then surface morphology and superhydrohobicity of these electrospun nanofibers were investigated. The results indicate that the water contact angle of the nanofiber surfaces goes up to 165° based on the fiber diameter, type of materials and surface porosity/roughness. Additives such as graphene, surfactant and titanium dioxide (2TiO) nanoparticles (nano powders) ranging from 10-25 nm were added into the same polymers (PVC, PS) and investigated to determine their performances. Both heat treatment and surface treatment were also applied to the fabricated fibers. The results with the additives indicate that the water contact angle is even further increased up to 178°. This may be because of the nanoscale voids (entrapped air) in the pores and surface energy of the nanofiber surface. These higher contact angle nanomaterials can have various industrial applications, such as non-wettable fabric, antibacterial surface, low friction devices, MEMS, NEMS, microfluidics and nanofluidics.<br>Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
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Dias, Dissanayake Anusha Shamini. "Performance enhancing oligomeric amide additives for epoxy resins." Thesis, Wichita State University, 2010. http://hdl.handle.net/10057/5438.
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Additives that enhance the mechanical properties of epoxy resins, by reducing the free
volume and thereby restricting the molecular motions, are known as antiplasticizers.
Antiplasticizers usually increase the modulus and strength but can decrease the glass transition temperature of the material.
A series of oligomeric amide additives were synthesised, that would, when mixed with
TGDDM and DDS, react to form strong hydrogen bonds and reduce the free volume in the
system. The effect of end group functionality was tested by synthesising both amine terminated
and acid terminated additives. The ability of these additives to enhance the mechanical properties
of the cured resin was examined by conducting fracture toughness and tensile testing. Results
obtained for compact tension specimens and tensile testing specimens were inconclusive due to
unavoidable imperfections incurred during specimen preparation. The cure kinetics of the resin
was studied using Differential Scanning Calorimetry or DSC. Dynamic temperature scanning
DSC indicated that the cure reaction was not affected significantly by these additives. At higher
heating rates, as expected, the degree of cure and rate of cure shifted to higher temperatures.
Arrhenius type activation energy calculations showed that incorporating amine terminated
additive did not significantly increase the activation energy of cure (Ea). However, a significant
increase in Ea was observed when the resin was cured with acid terminated additive. DMA and
TMA data indicated that the glass transition temperature of the matrix did not show a significant
reduction upon addition of the additives to the resin. Thermal degradation of the resin was
studied using Thermo Gravimetric Analysis or TGA. Results indicated that the presence of an additive does not affect the thermal stability of the resin.<br>Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Chemistry
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Valestrand, Anders J., and André Svendsvoll Langnes. "Anti Abrasive Additives for Hard Rock TBM Tunnelling." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23421.
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This master?s thesis is written in cooperation with NTNU, Robbins and BASF,with the aim to document the machine performance and production, when usingthe anti-abrasion agent ABR5 versus water. In a traditional hard rock TBM wateris sprayed on the cutters to cool them and suppress dust. Earlier studies indicatethat the use of foam can reduce cutter wear, temperature, dust production andlead to cleaner cutter tools.The work on the thesis is mainly based on 8 weeks of field studies on a 10mdiameter TBM at the AMR water irrigation project in India. To document theeffects of using foam versus water the main scopes are to record and examine cutterwear and life, measure dust and log temperature of the cutters as well as generalTBM performance. All this is seen in relation to the geology.This thesis suggests that foam has benefits in hard rock TBM tunnelling compared to water, but more research must be conducted with longer, and more consistent test periods. After boring 188 metres with foam, split into two intervals,the amount of blocked cutters has decreased with 47.8 percent. When comparingthe foam boring in the period between March 1. and May 12. a reduction in cutterwear of 12.7 percent was achieved. In the same period cutter life increased with18.2 percent cubic metres per cutter and 713 meters longer rolling distance. The amount of time spent on cutter changes is 34.2 percent less with foam. Temperature and dust measurements show slightly favourable values when boring with foam, but the data for these are too narrow to draw any conclusion.