Rotationally averaged polarizabilities and intrinsic electric dipole moments of sodium clusters are measured and reported. The experimental method is a molecular beam deflection. Our precision is the highest (<5%) and the range of the cluster sizes is the broadest to date (Na₁₀ ∼ Na₃₀₀). Compared to the earlier measurements, our data covers all sizes with no gaps up to the largest cluster. The fine structure in the polarizability curve is previously unobserved. We have carefully ruled out several possible explanations. And we find an earlier existing theory could explain the facts but will lead to magic numbers which were not seen in some previous experiments. A detailed theory is needed to understand the behaviors we see. Intrinsic electric dipole moments (EDM) of sodium clusters are probed to answer the intriguing question: Do metal clusters develop electric dipole moments like molecules? Some theories have predicted the existence of EDM in ground state sodium clusters and gave their magnitudes. We put upper bounds on the EDM of sodium clusters and find that they are orders of magnitude smaller than the predictions. This provokes an interesting question: how can one define metallicity in metal clusters? Our measurements are performed at cryogenic temperature 20 Kelvin. At this temperature the clusters are believed to be in their vibronic ground states.

This research project, funded by the Federal Highway Administration (FHWA Project DTFH61-02-C-0097), focuses mainly on alkali-silica reaction (ASR) and techniques to mitigate the effects of alkali-silica reaction in hardened concrete. A large portion of this report discusses the construction and design of an outdoor exposure site built at the University of Texas at Austin where the goal was to cast field representative concrete elements with laboratory precision and expose them to real environmental conditions. The elements were monitored for expansion and deterioration. At discrete expansion levels a range of mitigation methods were implemented on the structures. After the concrete elements were treated, long-term monitoring was conducted to determine the best approach to provide effective suppression of alkali-silica reaction in the various element types. / text

Recently, oil prices and oil demand are rising and are projected to continue to rise over the long term. These trends create great potential for enhanced oil recovery methods that could improve the recovery efficiency of reservoirs all over the world. The greatest challenges for enhanced oil recovery involve the technical uncertainty with design and performance, and the high financial risk. Pilot tests can help mitigate the risk associated with such projects; however, there is a question about the value of information from the tests. Decision support can provide information about the value of an enhanced oil recovery project, which can assist with alleviating financial risk and create more potential opportunities for the technology. The first objective of this study is to create a new simplified method for modeling oil production histories of enhanced oil recovery methods. The method is designed to satisfy three criteria: 1) it allows for quick simulations based on only a few physically meaningful input parameters; 2) it can create almost any potential type of realistic production history that may be realized during a project; and 3) it applies to all nonthermal enhanced oil recovery methods, including surfactant-polymer, alkali-surfactant polymer, and CO₂ floods. The developed method is capable of creating realistic curves with only four unique parameters. The second objective is to evaluate the predictive method against data from pilot and field scale projects. The evaluations demonstrate that the method can fit most realistic production histories as well as provided ranges for the input parameters. A sensitivity analysis is also performed to assist with determining how all of the parameters involved with the predictive method and the economic model influence the forecasted value for a project. The analysis suggests that the price of oil, change in oil saturation, and the size of the reservoir are the most influential parameters. The final objective is to establish a method for a decision analysis that determines the value of information of a pilot for enhanced oil recovery. The analysis uses the predictive method and economic model for determining economic utilities for every potential outcome. It uses a decision-based method to ensure that the non-informative prior probability distributions have an unbiased, consistent, and rational starting point. A simple example demonstrating the process is discussed and it is used to show that a pilot test provides some valuable information when there is minimal prior information. For future work it is recommended that more evaluations are performed, the decision analysis is expanded to include more input parameters, and a rational and logical method is developed for determining likelihood functions from existing information. / text

This research project, funded by the Federal Highway Administration, entails the construction of an outdoor exposure site in order to evaluate various methods for mitigating alkali-silica reaction (ASR) in hardened concrete. The exposure site, built at the Concrete Durability Center at the University of Texas at Austin J.J. Pickle Research campus, included a series of bridge deck, column and slab elements. The specimens were cast in 2008, allowed to expand to predetermined expansion levels and then treated with various mitigation measures, after which the specimens were monitored for expansion, humidity, and deterioration. / text

No description available.

The purpose of this project was to produce a “greener” cement from granulated ground blast furnace slag (GGBS) using non-Portland cement activation. By eventually developing “greener” cement, the ultimate goal of this research project would be to reduce the amount of Portland cement used in concrete, therefore reducing the amount of carbon dioxide emitted into the atmosphere during cement production. This research studies the behavior of mineral binders that do not contain Portland cement but instead comprise GGBS activated by calcium compounds or fluidized bed combustion (FBC) bottom ash. The information described in this paper was collected from experiments including calorimetry, which is a measure of the release of heat from a particular reaction, the determination of activation energy of cement hydration, mechanical strength determination, and pH measurement and identification of crystalline phases using X-ray diffraction (XRD). The results indicated that it is possible to produce alkali-activated binders with incorporated slag, and bottom ash, which have mechanical properties similar to ordinary Portland cement (OPC). It was determined that the binder systems can incorporate up to 40% bottom ash without any major influence on binder quality. These are positive results in the search for “greener cement”.

Effects of urban air pollution on health and environment have lead researchers to find economic air quality monitoring regulations. Since tin dioxide (SnO2) was demonstrated as a gas sensing device in 1962, tin oxide based thin film sensors have been widely studied due to their high sensitivity and fast response. The main advantages of using tin oxide sensors are their low cost, small size and low power consumption for mobile system applications. But, in order SnO2 based sensors to meet low concentration of gases they should be highly upgraded in sensitivity, selectivity and stability. This study was focused on the capacity of dopants in the SnO2 layer to increase the sensitivity of the sensor in detecting carbon monoxide. 1 wt. % Pd promoted and 0.1 wt. % Na-1 % Pd promoted SnO2 multilayer thin films were produced by sol-gel technique followed by spin coating route on soda-lime glass substrates. The EDX and SEM studies showed the surface composition and the surface structure is homogeneous throughout the films. The film thickness was determined app. 450 nm from the SEM image of the cross-section, after coating 8 layers. The experiments conducted at several temperatures namely 150, 175 and 200oC, in oxygen free and 1% oxygen containing atmospheres showed that the responses at higher temperatures in the presence of oxygen were much sharper with respect to others. Besides, Na promoted test sensors showed larger responses with shorter response time in oxygen free atmospheres at relatively lower temperatures. The results showed that the sensor signal is not directly correlated with the carbon dioxide production in oxygen free atmospheres.

The Bayer process for the production of alumina (A1203) from bauxite involves a perennial gibbsite (y-Al(OH)3) precipitation step, relating to an inherently slow crystal growth from supersaturated sodium aluminate solutions (pregnant Bayer liquors). The kinetics and mechanisms involved in the transformation of the tetrahydroxo, Al(III)-containing species in solution into octahedrally-coordinated Al(OH)3 crystals in the presence of NA+ and excess of ions, are as yet not fully known. To gain further knowledge and better understanding of the nature of solution species, their specific interaction and participation in the gibbsite crystallization mechanisms, the role alkali ions play in the kinetic behaviour and mechanisms of nucleation, growth and aggregation/agglomeration from caustic aluminate solutions of industrial strength has been investigated.

Alguns materiais, constituídos quase que exclusivamente por sílica, são empregados, de forma suplementar ao cimento Portland, por promoverem melhorias ao concreto, devido aos seus efeitos físicos e pozolânicos, além de atenderem a questões ambientais. No entanto, essa sílica pode gerar produtos indesejados na presença de álcalis, sendo este fenômeno conhecido como reação álcali sílica (RAS). Na presença de água, esses produtos são capazes de expandir no interior da massa de concreto, provocando fissuras internas e externas e, em casos mais graves, a degradação do elemento estrutural. Com a finalidade de evitar essa manifestação patológica, o presente trabalho propõe-se avaliar o potencial reativo frente à RAS da sílica ativa e dois tipos de cinzas da casca do arroz (CCA), uma comercial e outra residual. Nessa investigação foram adotados os teores de 5 a 50 %, utilizados como substituição parcial ao cimento Portland padrão. Os métodos de ensaio adotados nesta pesquisa foram o método acelerado em barras de argamassa segundo a NBR 15577 - 4/5, e dois novos métodos acelerados (cubos de pasta e prismas). O métodos acelerado em cubos de pasta avaliou a resistência à compressão, enquanto o método em prismas de pasta avaliou a variação dimensional. Os resultados obtidos em barras de argamassa apontaram que ambas as CCA investigadas, foram reativos frente à RAS. No entanto, o teor de 50 %, em ambas as CCA, se mostrou inócuo para essa reação. A sílica ativa foi considerada inócua em todos os teores avaliados. O aditivo superplastificante empregado não foi eficiente em reduzir a expansão provocada pela CCA. Os ensaios que avaliaram a expansão em prismas de pasta apresentaram uma ótima correlação positiva com o método normalizado em barras de argamassa. Nos prismas de pasta com 25 % de CCA industrial foram identificados os compostos franzinite, chessexite e thaumasite. Estes compostos apresentaram morfologia de acículas ora tortuosas ora delgadas e retilíneas compondo todas as amostras coletadas dessa pasta. A análise termogravimétrica apontou o alto poder adsorvente de água dessa pasta. Em conclusão, o ensaio em prismas de pastas a 48°C com 1,25 % de Na2Oeq demonstrou ser um método prático laboratorialmente e apresentou um grande potencial para avaliar os materiais suplementares ao cimento Portland frente a RAS, além de facilitar identificação dos produtos que provocaram expansão. / Some materials, consisting almost exclusively for silica, are employed, supplementary form to Portland cement, for promoting improvements to concrete, due to their physical and pozzolanic effects and environmental issues. However, this silica may generate unwanted products in presence of alkalis. This phenomenon is known as alkali-silica reaction (ASR). In the presence of water, these products are able to expand inside concrete, generating internal and external cracks and, in severe cases, structural element degradation. In order to prevent this pathologic manifestation, the aim of the present study was to evaluate reactive potential in ASR of fume silica and two types of rice husk ash (RHA), a manufacturing and residual. Levels of 5 to 50 % were used as partial replacement to standard Portland cement. In the present study, accelerated method in mortar bars according to NBR 15577 - 4/5 and two new accelerated methods (pastes cubes and prisms) were used. Accelerated method in paste cubes evaluated compressive strength, while method in paste prims evaluated dimensional change. Results in mortar bars demonstrated, both RHA, were reactive to ASR. However, level of 50 %, both RHA, was innocuous to ASR. Fume silica was innocuous to ASR at all levels evaluated. Superplasticizer additive was not effective to reduce to expansion caused by RHA. In the cubes assay was possible to evaluate the reactive potential to ASR by analysis of variation coefficient. Results demonstrated a positive correlation between expansion in paste prism and standard method in mortar bars. In the paste prism with 25 % of RHA manufacturing were identified compounds of franzinite, chessexite and thaumasite. These compounds presented morphology of needles sometimes tortuous and sometimes thin and straight in all samples. Thermogravimetric analysis showed the high adsorbent power of water in this paste. In conclusion, paste prims assay at 48ºC with Na2Oeq 1.25 % demonstrated to be a practical laboratory method and presented a great potential to evaluate additional material to Portland cement in front of ARS, and this assay facilitates the identifications of products that cause expansion.

Made available in DSpace on 2016-08-31T13:15:06Z (GMT). No. of bitstreams: 1 TalitaBAD_DISSERT.pdf: 1199750 bytes, checksum: 6beacf2ab995069e2c168a6be1d1f249 (MD5) Previous issue date: 2012-03-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The production of castor bean in the Apodi Plateau can be used as an alternative to crop rotation schemes aimed at economic and environmental sustainability of areas traditionally cultivated cucurbits. For the castor produce satisfactorily, the adaptation to climate conditions and the use of appropriate farming is essential to have supplies of water and nutrients. In alkaline soils, the availability of some nutrients become limited, especially micronutrients; nitrogen, when applied in this type of soil can be quickly lost to the atmosphere by volatilization of ammonia, and the main occurrence of this loss occurs with the use of urea. This work aimed to evaluate the response of castor bean doses of potassium, boron, zinc, copper, magnesium and nitrogen sources applied at planting and coverage in order to contribute to the improvement of its productive system in the Apodi Plateau . In experiment 01, 10 treatments were compared regarding the soil application of five doses of potassium (0, 25, 50, 75 and 100 kg ha-1) and five doses of boron (0.0, 0.5, 1.0, 2.0 and 3.0 kg ha-1). In experiment 02, compared to seven treatments with the aim of evaluating the effects of the presence and absence of fertilization with Zn, Cu and Mg and the effects of forms of use (cultivation and or coverage) of N sources (urea and , or, ammonium sulfate). At 47 days after emergence composite samples were collected at depth 0-20 cm from the floor area of each plot, to determine the levels of K, Zn, Cu and Mg available. At the beginning of flowering of castor beans was assessed the nutritional status of plants, determining the K, B, Zn, Cu, Mg, S and N in the leaves. At the end of the experiment were evaluated: plant height, height of insertion of the primary raceme, stem diameter, number of racemes per plant, thousand grain weight of the raceme and primary and subsequent productivity. Under the experimental conditions, the average productivity of castor beans was 2.019 kg ha-1 grain, without requiring fertilization with potassium, boron, copper, zinc and magnesium, and indiscriminately using urea or ammonium sulfate as nitrogen source for crop fertilization and or cover, incorporated into the soil 5 cm in depth / A produção da mamona na Chapada do Apodi pode ser utilizada como alternativa para os sistemas de rotação de culturas que visem à sustentabilidade econômica e ambiental de áreas tradicionalmente cultivadas com cucurbitáceas. Para que a mamona produza satisfatoriamente, além de adaptação às condições edafoclimáticas e da utilização da cultivar adequada, é imprescindível que haja suprimentos de água e de nutrientes. Em solos alcalinos, a disponibilidade de alguns nutrientes torna-se restrita, principalmenteos micronutrientes; o nitrogênio, quando aplicado neste tipo de solo pode ser rapidamente perdido para atmosfera por volatilização da amônia, e a principal ocorrência dessa perda acontece com a utilização de uréia. Neste trabalho objetivou-se avaliar a resposta da cultura da mamona a doses de potássio, boro, zinco, cobre, magnésio e a fontes de nitrogênio aplicadas no plantio e em cobertura, de forma a contribuir para a melhoria do seu sistema produtivo na Chapada do Apodi. No experimento 01, foram comparados 10 tratamentos referentes à aplicação, no solo, de cinco doses de potássio (0, 25, 50, 75 e 100 kg ha -1) e cinco doses de boro (0,0, 0,5, 1,0, 2,0 e 3,0 kg ha -1). No experimento 02, compararam-se sete tratamentos, com o objetivo de avaliar os efeitos da presença e ausência de adubação com Zn, Cu e Mg e os efeitos de formas de utilização (plantio e, ou, cobertura) de fontes de N (uréia e, ou, sulfato de amônio). Aos 47 dias após a emergência foram coletadas amostras compostas de solo na profundidade de 0 a 20 cm da área útil de cada parcela, para determinação dos teores de K, Zn, Cu e Mg disponíveis. No início do florescimento da mamoneira foi avaliado o estado nutricional das plantas, determinando-se os teores de K, B, Zn, Cu, Mg, S e N nas folhas. Ao final do experimento, foram avaliadas a altura da planta, altura de inserção do racemo primário, o diâmetro do caule, número de racemos por planta, massa de mil grãos do racemo primário e subsequentes e produtividade. Nas condições experimentais, a produtividade média da mamoneira foi 2.019 kg ha-1 de grãos, sem necessitar de adubação com potássio, boro, cobre, zinco e magnésio, e utilizando indistintamente a uréia ou sulfato de amônio como fonte de nitrogênio para adubação de plantio e, ou, de cobertura, incorporada no solo a 5 cm de profundidade