Tree-Shaped Fluid Flow and Heat Transfe

This book is an attempt to present a comprehensive overview of the fundamentals in the area of tree flow networks. Emphasis is placed on the understanding of the design features of these networks and on their significance to the transport phenomena associated with these systems. It is intended to bring into perspective the relevant research that has been performed, mainly that which provides the reader with a comprehensive overview of the topic

Avaliação do período de floração e frutificação do BAG Ipecacuanha.

A ipecacuanha (Carapichea ipecacuanha (Brot.) L. Anderson Lorenzi, 2008) conhecida popularmente como ipeca e poaia, pertencente à família Rubiaceae é uma espécie medicinal de potencial econômico, onde sua raiz e obtida diretamente do extrativismo, sendo cada vez mais rara em seu habitat natural. O estudo da fenologia no Banco Ativo de Germoplasma (BAG) de Ipecacuanha da Embrapa Amazônia Oriental permitiu que a floração e frutificação desta espécie fossem avaliadas diariamente dentro do período de abril de 2009 à setembro de 2010. O BAG de Ipecacuanha apresentou floração de setembro de 2009 à setembro de 2010. Quanto à frutificação, apenas um acesso frutificou nos meses de março e agosto de 2010.PIBIC-2011

DNA-psoralen: single-molecule experiments and first principles calculations

The authors measure the persistence and contour lengths of DNA-psoralen complexes, as a function of psoralen concentration, for intercalated and crosslinked complexes. In both cases, the persistence length monotonically increases until a certain critical concentration is reached, above which it abruptly decreases and remains approximately constant. The contour length of the complexes exhibits no such discontinuous behavior. By fitting the relative increase of the contour length to the neighbor exclusion model, we obtain the exclusion number and the intrinsic intercalating constant of the psoralen-DNA interaction. Ab initio calculations are employed in order to provide an atomistic picture of these experimental findings.Comment: 9 pages, 4 figures in re-print format 3 pages, 4 figures in the published versio

Clusters and Upgrading: a Purposeful Approach

We develop a theoretical model to investigate how backward societies can improve their upgrading capabilities by transforming existing industrial agglomerations into dynamic clusters. Our main assumptions are two: first, emerging market economies are not uniform but characterized by variety of subnational regional and sectoral organizational and institutional configurations; second, the basic building block and unit of explanation in social sciences is personal action guided by some intention, which is heterogeneous across different actors. Based on these assumptions and the literature on human motives and social networks, we develop a purposeful approach to clusters and upgrading. We argue that governments can develop institutions with private actors that facilitate new types of relationships and improve the access local firms have to a variety of knowledge resources, a key ingre­dient to upgrading. We illustrate this argument revisiting the literature on clusters and upgrading in Latin America and using two case studies in Argentina, a country better known for its volatility and lack of optimal social capital and institutions. We conclude with avenues for further research

Special Focus on: Optimal Fluid Systems & Machinery

The competitive cost of numerical simulations over laboratory studies, due to the continued advancements in computing performance, has made computational fluid dynamics an integral tool in the study of engineering problems. This topical special focus issue “Optimal Fluid Systems and Machinery” of the Journal of Research on Engineering Structures & Materials (RESM) covers a varied range of engineering systems. It contains papers selected on the basis of the results of regular peer review of the short manuscripts submitted for consideration by the participants of the Special Session “Fluid Flow, Energy Transfer and Design” at the 13th International Conference on Diffusion in Solids and Liquids (DSL2018) held in Vienna, Austria

Transport Problems with a Focus on Fluid and Heat Flow

The presented volume “Transport Problems with a Focus on Fluid and Heat Flow” covers in a wider sense diffusion related phenomena. The basic phenomena of heat and mass transfer play an important role in basic and applied research and this volume presents a balanced collection of recent developments in this are

Towards absolute calibration of optical tweezers

Aiming at absolute force calibration of optical tweezers, following a critical review of proposed theoretical models, we present and test the results of MDSA (Mie-Debye-Spherical Aberration) theory, an extension of a previous (MD) model, taking account of spherical aberration at the glass/water interface. This first-principles theory is formulated entirely in terms of experimentally accessible parameters (none adjustable). Careful experimental tests of the MDSA theory, undertaken at two laboratories, with very different setups, are described. A detailed description is given of the procedures employed to measure laser beam waist, local beam power at the transparent microspheres trapped by the tweezers, microsphere radius and the trap transverse stiffness, as a function of radius and height in the (inverted microscope) sample chamber. We find generally very good agreement with MDSA theory predictions, for a wide size range, from the Rayleigh domain to large radii, including the values most often employed in practice, and at different chamber heights, both with objective overfilling and underfilling. The results asymptotically approach geometrical optics in the mean over size intervals, as they should, and this already happens for size parameters not much larger than unity. MDSA predictions for the trapping threshold, position of stiffness peak, stiffness variation with height, multiple equilibrium points and `hopping' effects among them are verified. Remaining discrepancies are ascribed to focus degradation, possibly arising from objective aberrations in the infrared, not yet included in MDSA theory.Comment: 15 pages, 20 figure

Corrosão de interfaces ti/al2o3 em solucões fisiologicas simuladas

Nos últimos anos o estudo das interfaces metal/cerâmico (M/C) tem despertado grande interesse devido às diversas utilidades que estas podem oferecer em diferentes campos de aplicação prática. Um destes campos é o relativo à área das aplicações biomédicas. De entre os vários processos existentes para a produção de uniões M/C, as técnicas de união por difusão e de brasagem activa são algumas das mais utilizadas. Em qualquer uma destas técnicas, a alta temperatura envolvida no processo é um parâmetro que favorece o desenvolvimento de reacções químicas complexas que dão origem a interfaces multi-camadas cujas propriedades físico-químicas são complexas. Esta complexidade da interface, unida ao facto, já conhecido, de que as propriedades mecânicas, físicas e químicas, incluindo a resistência à corrosão, dependem da composição química e da microestrutura da região interfacial, fazem com que seja necessário um melhor conhecimento da natureza e das características físico-químicas desta região, de forma a poder controlar mais estritamente as propriedades da interface. O principal objectivo deste trabalho é o estudo do comportamento à corrosão de interfaces Ti/Al2O3 produzidas pela técnica de união por brasagem activa. Para efectuar este estudo para além da interface, foram produzidas ligas com composições químicas similares a cada camada interfacial, as quais foram testadas através de ensaios electroquímicos de corrente directa, nomeadamente, polarização potenciodinâmica, resistência à polarização e corrosão galvânica. Neste trabalho, será descrito o comportamento à corrosão da interface, assim como o efeito que a interacção entre as diferentes camadas presentes na interface produz sobre o comportamento à degradação geral da interface Ti/Al2O3.Fundação para a Ciência e a Tecnologia (FCT), Portugal (Projectos POCTI/CTM/33384/2000 e SFRH/BPD/5518/2001)