Orientador: Ines Joekes / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-11T02:24:57Z (GMT). No. of bitstreams: 1 Silva_NelsonSilkunasda_M.pdf: 522816 bytes, checksum: 99774b9c46cdd62d41438af35afb8ac3 (MD5) Previous issue date: 2007 / Resumo: Uma das áreas mais importantes da química dos materiais a base de cimento é a procura pela melhoria das propriedades destes materiais utilizando-se aditivos. Neste trabalho desenvolveu-se um aditivo a base de dodecilbenzenossulfonato de sódio (SDBS), um superplastificante, e dibutilftalato (DBP), um plastificante de PVAc que pode ser um desincorporador de ar. Inicialmente foi estabelecido o poder desincorporador de ar do dibutilftalato em argamassa, pasta e concreto de cimento portland, obtendo-se resultados de desincorporação de até 95 % do ar incorporado nas preparações. A seguir foram confeccionados corpos de prova de argamassa de cimento CP III 32 RS, traço 1:3 e relação água cimento de 0,40 com o aditivo misto em várias concentrações. Os corpos de prova foram ensaiados para sorção de água e resistência à compressão. Verificou-se que a formulação mais rica em SDBS (80 % de SDBS e 20 % de DBP, em massa) aumenta impermeabilidade (até 3 vezes), mas não aumenta a resistência à compressão proporcionalmente, indicando incorporação excessiva de ar. Com a formulação mais rica em DBP (80 % DBP e 20 % SDBS, em massa) aumenta a impermeabilidade (até 2 vezes) e a resistência à compressão (até 25 % em relação ao controle). Com este aditivo foi possível reduzir a relação água cimento para 0,35 o que aumentou a resistência à compressão em cerca de 40 %. Estes resultados mostram que o aditivo formulado pode ser usado para incrementar a resistência à compressão e a impermeabilidade de argamassas, competindo em preço com os de mercado / Abstract: An important area in the field of cement based materials is the search for additives that improve the properties of these materials. In this work, an admixture containing sodium dodecylbenzene sulfonate (SDBS), a superplasticizer, and dibutylphtalate (DBP), a plasticizer used in PVAc which can also be used as an air entrapment reducer, was developed. Initially, the effectiveness of DBP as air entrapment reducer was tested in pastes, mortars and concrete, obtaining results as high as 95 % reduction. Then, mortar test specimens with slag modified cement, sand-to-cement ratio 3:1 and water-to-cement ratio 0.40 were prepared using the mixed additive in different concentrations in the water. The specimens were tested for water sorption and compressive strength. It was observed that the additive formulation richest in SDBS (80 % SDBS and 20 % DBP) increases the impermeability (up to 3 times) but does not increase the compressive strength of the specimens in the same proportion, signaling that air entrapment is still high. Using the DBP richest formulation (80 % DBP and 20 % SDBS) increases the waterproofing (up to 2 times) and also the compressive strength (up to 25 %). With this additive it was possible to prepare test specimens with a water cement ratio 0.35 and a compressive strength increase of near 40 %. These results show that the admixture developed can be used to increase the impermeability and compressive strength of mortars, competing properly in price with those available in the market / Mestrado / Físico-Química / Mestre em Química

The scientific development of innovative molecular techniques has transformed the approach towards human identification. In forensic casework, the emergence of molecular phenotyping, or phenotypic prediction from DNA, has mitigated some challenges involving the unavailability of references samples for traditional forensic DNA analysis. Molecular phenotyping via SNP analysis can be used as a tool in a forensic setting to predict physical traits, such as hair, skin and eye colour, and provide investigative leads. Several ancestry informative markers (AIMs) have previously been associated with human skin colour in mainly the European and North American population groups, while admixed populations are hardly studied. The present study aims to contribute towards this gap by investigating the relationship between two AIMs (SLC45A2, rs16891982 and SLC24A5, rs1426654) that are typically involved in molecular phenotyping, and melanin index (MI) in the South African (SA) metapopulation (n = 389). The self-reported ancestry, ethnicity and relevant biographic information for each participant was documented and MI was recorded using a dermaspectrophotometer. DNA was extracted from saliva samples and PCR amplification of target regions was performed. Thereafter, SNaPshot® PCR was used to genotype the variants. Significant differences (p < 0.0001) were observed between MI readings and ancestral as well as population census groups. A generalised linear model (GLM) was developed which could accurately predicted the MI readings for each genotype combination within the 95 % confidence interval of the recorded MI readings. Our results suggest that these two markers were consistently associated with MI in the admixed SA population and are thus informative to predict MI in a forensic setting. Finally, this was the first study in a SA context to use SNP analysis for objective MI prediction.

This multifaceted study primarily aimed at understanding the genetic make-up of captive versus wild cheetah (Acinonyx jubatus) populations in South Africa, with a specific emphasis on a valuable gene pool of a recessive phenotype that is increasingly being maintained in captive population country-wide. The current literature on cheetah genetics has very little information on diversity levels of wild South African cheetahs, and no information on founder dynamics and genetic make-up of South African captive populations. Decisions on cheetah relocations are being made, implementing current conservation policy, from assumptions on origin and relatedness. This research compared population genetic parameters within the largest South African captive cheetah population to free-ranging Namibian and South African conspecifics. The study addressed concerns regarding excessive Namibian genetic introgression into the native captive population and established the extent of genetic variability and Namibian ancestry within the captive population. The study has attempted to address the rising concern among conservation officials with respect to illegal trade of wild-captured cheetahs, wild caught cheetahs that are sold as captive-bred after implanting a microchip. In addition to establishing routine parentage verification using genetic markers that are polymorphic in this species, this study established a technique powerful enough to estimate ancestry in cheetahs of unknown antecedents. The potential of spatial Bayesian clustering to differentiate the point of origin of unknown cheetahs was exploited and in addition, a database for future forensic efforts to address the problem of illegal trade was established. The captive population that was part of this dataset proved to be quite admixed, excepting for the King lineage which was distinct. The second aspect of this study investigated complex conditions such as development of gastritis, renal conditions and/or susceptibility to infections and its relation to pedigree and marker based inbreeding levels. Heritability values for important breeding traits were estimated from pedigree records of 532 cheetahs and are reported for the first time. Gastritis was weakly correlated to the expression of the King trait. Finally, a smaller cohort of the captive pedigree that segregates for a recessive colour variant called the King phenotype was tested for the assumption that the variation is a mutation of the tabby locus described in domestic cats. Genetic linkage analysis was done by testing microsatellite markers detected linked to Tabby for linkage to a conserved region in the cheetah that potentially codes for the King coat colour. Genetic linkage analysis was not detected between the King locus and the domestic cat microsatellite markers used for this study, with LOD scores remaining non-significant for all the markers. / Thesis (PhD)--University of Pretoria, 2011. / Production Animal Studies / unrestricted

Yes / Reactive Powder Concrete (RPC) is a new type of cementitious materials with a complex hydration mechanism, and active admixtures greatly influence the hydration reaction, formation of hydration products, and evolution of microstructure. In order to comprehensively study the quantitative effects of active admixtures contents, namely silica fume, slag and fly ash, on hydration characteristics, hydration products, and microstructure of RPCs, tests of workability, setting time, electrical conductivity, bound water and mechanical properties were conducted. Furthermore, a series of properties including morphology and micro-structure characteristics of RPCs were analyzed by thermogravimetric (TG) analysis, X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), mercury intrusion porosimetry (MIP), Brunauer-Emmet-Teller (BET), and scanning electron microscope (SEM). The results indicate that the initial hydration reaction rate of RPCs is reduced by partly replacing cement with active admixtures. The pozzolanic effect created by the active admixtures enhances hydration and improves RPC's compressive and flexural strength. RPCs made of cement-silica fume mixture exhibit the best macroscopic properties. The adoption of silica fume promotes the production of C-S-H gel during hydration and exerts pozzolanic and crystal nucleation effects to promote cement hydration. RPCs made of pure cement exhibit 15.3% porosity after 28 days of hydration, with the largest proportion of less harmful pores in the microstructure. The porosity is reduced to 5.2% when cement is partially replaced with silica fume, and the microstructure is dominated by harmless pores. When replacement of silica fume is kept at 25%, using slag powder or fly ash substitute part of cement also reduces the number of less harmful pores. It is beneficial to add slag powder to increase the number of gel pores, whereas fly ash reduces the number of gel pores. The investigation presented in this paper would contribute to the production of low cost and environmentally-friendly RPCs, and accelerate the wider applications of ultra-high performance concrete (UHPC) in engineering structures.

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Yes / The inclusion of crystalline admixture (CA) is a highly effective method for enhancing the self-repairing capabilities of mortar. This study examined the complexing abilities of different complexing agents under varying temperatures, pH levels, and ion species in order to select effective complexing agents for diverse environments, as complexing agents play a crucial role in CAs. After determining the type of complexing agent, an orthogonal array design was used to optimize the components of CA, and the strengthening mechanism of CA for mortar was discussed through microstructure analysis. The results showed that the complexation behavior of triethanolamine (TEA) and glycine performed better than sodium citrate (SC) for different pH, temperatures, and ion species. Meanwhile, TEA and glycine showed complementarity at different stages, so TEA and glycine were used as complexing agents in this study. Based on the orthogonal experiment, the optimal contents of Na2SiO3, Na2CO3, TEA, glycine, Ca(COOH)2, and nano-SiO2 in CA were determined to be 1.0%, 1.0%, 0.04%, 1.0%, 0.5%, and 1.0%, respectively. Under the synergistic effect of TEA and glycine, the hydration of aluminate and ferrialuminate was accelerated, and the hydration degree of cement paste was increased. At 28 d, the contents of CaCO3, C-S-H gel, and ettringite of cement paste with CA were higher than these of plain paste, but its Ca(OH)2 content was lower. Although the Ca(OH)2 content in the cement paste with CA was lower, the Ca(OH)2 crystal structure filled in the pores was larger. Therefore, the mortar mixed with CA exhibited higher compressive strength, water impermeability, and self-healing ability. / The full-text of this article will be released for public view at the end of the publisher embargo on 3 May 2025.

The complex interaction between cement and chemical/mineral admixtures in concrete mixtures sometimes leads to unpredictable concrete performance in the field which is generally defined as concrete incompatibilities. Cement paste rheology measurements instead of traditional workability tests (i.e., slump cone test) can have great potential in detecting those incompatibilities in concrete before the concrete is placed, which can, in turn, avoid related workability problems and setting time as well as heat evolution abnormalities. The objectives of the present study were to examine the applicability of the dynamic shear rheometer (DSR) to measure cement paste rheology, and to identify cement and mineral/chemical admixture incompatibilities, based on the determined rheological parameters. The DSR was modified and optimized for cement paste rheology measurements. Two different modes of operations (i.e., static and dynamic methods) with the modified DSR were investigated to measure representative rheological parameters as well as to identify cement and chemical/mineral admixture incompatibility. The conventional plastic viscosity and yield stress are measured in static mode and storage modulus curve, as a function of time, is measured in dynamic mode. The rate of change of plastic viscosity (RPV) as another static rheological parameter and the modeled magnitude parameter ?, from the dynamic rheological method, showed great potentialities as acceptance criteria to identify incompatible mixtures. The heat of hydration data from isothermal conduction calorimeter tests and setting time results for the studied mixtures have strongly supported the rheology based observations as supporting tools. Based on the main tests results, the acceptance criteria were set up using the rheological parameters in accordance with heat of hydration data. This will ultimately help material suppliers, concrete producers, and other users to detect problematic combinations of concrete ingredients before a given concrete mixture is placed.

Les invasions biologiques ont des conséquences écologiques telles que l'émergence de pathogènes et de ravageurs. Les populations invasives font face à de nouvelles conditions biotiques et abiotiques qu'elles doivent surmonter. Ces invasions biologiques sont des systèmes modèles pour étudier l'évolution sur de courtes échelles de temps car elles nécessitent une adaptation rapide qui fait intervenir différents processus (sélection naturelle, dérive, plasticité phénotypique). Du fait des introductions multiples et de l'hybridation, une augmentation de la variabilité génétique nucléaire peut-être observée dans ces populations, support d'une réponse adaptative plus rapide. De plus, chez les insectes, les symbiotes peuvent jouer un rôle important dans l'adaptation, contribution encore largement inconnue. Le ravageur de culture Bemisia tabaci est un complexe d'espèces dont les barrières reproductives sont peu connues et dont les différentes entités --- les cytotypes --- présentent des cortèges symbiotiques qui leur sont spécifiques. Grâce à une description de la dynamique spatio-temporelle de ces cytotypes, en contexte invasif en France et plus largement dans le bassin méditerranéen, nous avons constaté la présence simultanée de deux de ces entités et nous nous sommes interrogés sur un éventuel remplacement ou une coexistence. Cette situation originale nous a permis de tester leurs limites reproductives grâce à des microsatellites et des tests comportementaux, ainsi que la possibilité de transferts horizontaux de bactéries. Transferts que nous avons tenté de reproduire en laboratoire. Nous avons aussi développé des marqueurs RADSeq pour de futures analyses génomiques / Biological invasions have ecological consequences such as the emergence of pathogens and pests. Invasive populations face new biotic and abiotic conditions that they have to overcome.These biological invasions are model systems to study the evolution over short time scales because they require rapid adaptation that involves different processes (natural selection, drift, phenotypic plasticity).Because multiple introductions and hybridization, an increase in the nuclear genetic variability may be observed in these populations, supporting a faster adaptive response.Moreover, in insects, symbionts can play an important role in adaptation, a contribution largely unknown yet.Bemisia tabaci crop pest is a complex of species whose reproductive barriers are poorly known and whose different entities --- the cytotypes --- have symbiotic associations specific to them.Through a spatio-temporal dynamics description of these cytotypes in invasive context in France and more widely in the Mediterranean bassin, we found the simultaneous presence of both of these entities and we wondered about a possible replacement or coexistence.This peculiar situation has allowed us to test their reproductive boundaries with microsatellites and behavioral tests, as well as the possibility of horizontal transfer of bacteria. Transfers that we tried to reproduce in the laboratory. We have also developed RADSeq markers for future genomic analyzes

L'essor des marqueurs moléculaires (SNPs) a révolutionné les méthodes de génétique quantitative en permettant l'identification de régions impliquées dans le déterminisme génétique des caractères (QTLs) via la génétique d'association (GWAS), ou encore la prédiction des performances d'individus sur la base de leur information génomique (GS). La stratification des populations en groupes génétiques est courante en sélection animale et végétale. Cette structure peut impacter les méthodes de GWAS et de GS via des différences de fréquence et d'effets des allèles des QTL, ainsi que par des différences de déséquilibre de liaison (LD) entre SNP et QTL selon les groupes.Pendant cette thèse, deux panels de diversité de maïs ont été utilisés, présentant des niveaux différents de structuration: le panel “Amaizing Dent” représentant les lignées dentées utilisées en Europe et le panel “Flint-Dent” incluant des lignées dentées, cornées européennes, ainsi que des lignées admixées entre ces deux groupes.En GS, l'impact de la structure génétique sur la qualité des prédictions a été évalué au sein du premier panel pour des caractères de productivité et de phénologie. Cette étude a mis en évidence l'intérêt d'une population d'entraînement (TS) dont la constitution en matière de groupes génétiques est similaire à celle de la population à prédire. Assembler les différents groupes au sein d'un TS multi-groupe apparaît comme une solution efficace pour prédire un large spectre de diversité génétique. Des indicateurs a priori de la précision des prédictions génomiques, basés sur le coefficient de détermination, ont également été évalués, mettant en évidence une efficacité variable selon le groupe et le caractère étudié.Une nouvelle méthodologie GWAS a ensuite été développée pour étudier l'hétérogénéité des effets capturés par les SNPs selon les groupes. L'intégration des individus admixés à l'analyse permet de séparer les effets des facteurs responsables de l'hétérogénéité des effets alléliques: différence génomique locale (liée au LD ou à une mutation spécifique d'un groupe) ou interactions épistatiques entre le QTL et le fonds génétique. Cette méthodologie a été appliquée au panel “Flint-Dent” pour la précocité de floraison. Des QTL ont été détéctés comme présentant des effets groupe-spécifiques interagissant ou non avec le fonds génétique. De nombreux QTL présentant un profil original ont pu être mis en évidence, incluant des locus connus tels que Vgt1, Vgt2 ou Vgt3. Une importante épistasie directionnelle a aussi été mise en évidence grâce aux individus admixés, confortant l'existence d'interactions épistatiques avec le fonds génétique pour ce caractère.Sachant l'existence de cette hétérogénéité d’effets alléliques, nous avons développé deux modèles de prédictions génomiques nommées Multi-group Admixed GBLUP (MAGBLUP). Ceux-ci modélisent des effets groupe-spécifiques aux QTLs et sont adaptés à la prédiction d'individus admixés. Le premier permet d'identifier la variance génétique additionnelle créée par l'admixture (variance de ségrégation), alors que le second permet d'évaluer le degré de conservation des effets alléliques entre groupes. Ces deux modèles ont montré un intérêt certain par rapport à des modèles standards pour prédire des caractères simulés, mais plus limité sur des caractères réels.Enfin, l'intérêt des individus admixés dans la constitution de TS multi-groupes a été évalué à l'aide du second panel. Si leur intérêt a clairement été mis en évidence pour des caractères simulés, des résultats plus variables ont été observés avec les caractères réels, pouvant s'expliquer par la présence d'interactions avec le fonds génétique.Les nouvelles méthodes et l'utilisation d'individus admixés ouvrent des pistes de recherches intéressantes pour les études de génétique quantitative en population structurée. / The advent of molecular markers (SNPs) has revolutionized quantitative genetics methods by enabling the identification of regions involved in the genetic determinism of traits (QTLs) thanks to association studies (GWAS), or the prediction of the performance of individuals using genomic information (GS). The stratification of populations into genetic groups is common in animal and plant breeding. This structure can impact GWAS and GS methods through group differences in QTL allele frequencies and effects, as well as in linkage disequilibrium (LD) between SNP and QTL.During this thesis, two maize diversity panels were used, presenting different levels of structuration: the "Amaizing Dent" panel representing the diversity of dent lines used in Europe and the "Flint-Dent" panel including dent, flint and admixed lines between these two groups.In GS, the impact of genetic structure on genomic prediction accuracy was evaluated in the first panel for productivity and phenology traits. This study highlighted the interest of a training population (TS) whose constitution in terms of genetic groups is similar to that of the population to be predicted. Assembling the different groups within a multi-group TS appears as an effective solution to predict a broad spectrum of genetic diversity. A priori indicators of genomic prediction accuracy, based on the coefficient of determination, were also evaluated and highlighted a variable efficiency depending on the group and the trait.A new GWAS methodology was then developed to study the heterogeneity of the allele effects captured by SNPs depending on the group. The integration of admixed individuals to such analyses allows to disentangle the factors causing the heterogeneity of allele effects across groups: local genomic difference (related to LD or group-specific mutation) or epistatic interactions between the QTL and the genetic background. This methodology was applied to the "Flint-Dent" panel for flowering time. QTLs have been detected as presenting group-specific effects interacting or not with the genetic background. QTLs with an original profile have been highlighted, including known loci such as Vgt1, Vgt2 or Vgt3. Significant directional epistasis has also been demonstrated using admixed individuals and supported the existence of epistatic interactions with the genetic background for this trait.Based on the existence of such heterogeneity of allele effects, we have developed two genomic prediction models named Multi-group Admixed GBLUP (MAGBLUP). Both model group-specific QTL effects and are suited to the prediction of admixed individuals. The first allows the identification the additional genetic variance created by the admixture (segregation variance), while the second allows the evaluations of the degree of conservation of SNP allele effects across groups. These two models showed a certain interest compared to standard models to predict simulated traits, but it was more limited on real traits.Finally, the interest of admixed individuals in multi-group TS was evaluated using the second panel. Although their interest has been clearly demonstrated for simulated traits, more variable results have been observed with the real traits, which can be explained by the presence of interactions with the genetic background.The new methods and the use of admixed individuals open interesting lines of research for quantitative genetics studies in structured population.