21 research outputs found

    Sappho of the Cathedral

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    Einfluss eines Magnetfeldes auf die Drift von Elekronen in CO2 - Is0C4H10 - Gemischen

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    Staghorn Calculus: A Stone out of Proportion to Pain

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    Case Presentation: A 25-year-old woman presented to the emergency department with two weeks of crampy right-flank pain, and urinary urgency and frequency. She was found to have a staghorn calculus filling her entire right renal pelvis on computed tomography imaging.Discussion: In contrast to ureteral calculi, staghorn calculi are more commonly observed in female patients and typically present with an indolent clinical course. A low threshold for imaging should be maintained, as prompt referral to urology for stone removal or treatment is necessary. Staghorn calculi have a high likelihood of leading to renal failure or urosepsis without treatment

    Femtosecond multidimensional imaging of a molecular dissociation

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    The coupled electronic and vibrational motions governing chemical processes are best viewed from the molecule's point of view—the molecular frame. Measurements made in the laboratory frame often conceal information because of the random orientations the molecule can take. We used a combination of time-resolved photoelectron spectroscopy, multidimensional coincidence imaging spectroscopy, and ab initio computation to trace a complete reactant-to-product pathway—the photodissociation of the nitric oxide dimer—from the molecule's point of view, on the femtosecond time scale. This method revealed an elusive photochemical process involving intermediate electronic configurations

    Cinética de hidratação de ligantes à base de alumina hidratável ou aluminato de cálcio Kinetics of hydration of binders based on hydratable alumina or calcium aluminate cement

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    O estado de dispersão da matriz de um concreto refratário apresenta uma grande influência no comportamento reológico desse material, determinando as técnicas utilizadas para a sua aplicação. Tais métodos normalmente exigem a preparação de concretos com elevada fluidez, que possam ser bombeados com facilidade e sejam capazes de preencher moldes de formato complexo sem a necessidade de aplicação de vibração. Entretanto, embora tais requisitos favoreçam uma boa trabalhabilidade do concreto, tendem a aumentar o tempo requerido para efetuar a desmoldagem do corpo conformado. Uma vez que o desenvolvimento da resistência mecânica do concreto está intimamente relacionado ao processo de hidratação do ligante hidráulico, este necessita ser controlado quando se busca a redução do tempo para a desmoldagem. Tal controle depende de um profundo conhecimento das variáveis que determinam a cinética das reações. Neste contexto, o objetivo deste trabalho foi o de avaliar a influência do tipo de ligante hidráulico, da temperatura e da presença de finos (matriz) ou de aditivos inorgânicos adicionados ao concreto sobre o processo de hidratação por meio de medidas de temperatura e ensaios reológicos oscilatórios em função do tempo.<br>The dispersion of refractory castables matrix presents a great influence on their rheological behavior, which defines the most appropriate methods for placing these materials. The growing demand for automatically transported refractory castables has promoted the use of pumpable castables, usually specified as self flow compositions. Nevertheless, castables with higher fluidity present longer workability, leading to extended demoulding times. Because the strength development is intimately linked to the hydration process of calcium aluminate cement or hydratable alumina, it needs to be controlled in order to reach the minimum time for demoulding, contributing to reducing overall costs. The control of cement hydration depends on the knowledge of the variables that determine the kinetics of the involved reactions. In this context, the objective of this work was to evaluate the influence of the sources of the hydraulic binder, the temperature and the presence of matrix or inorganic additives on the hydration process, carried out through temperature measurements and oscillatory rheological tests, as a function of the time
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