493 research outputs found
Avaliação do teor e produtividade de óleo essencial de nove procedências de Lippia Alba no terceiro corte.
Composição do óleo essencial de Piper caldense C.D.C. e Piper solmsianum C.D.C. provenientes da Mata Atlântica do litoral do Paraná.
Visualization of Thin Liquid Crystal Bubbles in Microgravity
The Observation and Analysis of Smectic Islands in Space (OASIS) experiment exploits the unique characteristics of freely suspended liquid crystals in a microgravity environment to advance the understanding of fluid state physics
Microplastic in Surface Waters of Urban Rivers: Concentration, Sources, and Associated Bacterial Assemblages
The ecological dynamics of microplastic (\u3c5 mm) are well documented in marine ecosystems, but the sources, abundance, and ecological role of microplastic in rivers are unknown and likely to be substantial. Microplastic fibers (e.g., synthetic fabrics) and pellets (e.g., abrasives in personal care products) are abundant in wastewater treatment plant (WWTP) effluent, and can serve as a point source of microplastic in rivers. The buoyancy, hydrophobic surface, and long transport distance of microplastic make it a novel substrate for the selection and dispersal of unique microbial assemblages. We measured microplastic concentration and bacterial assemblage composition on microplastic and natural surfaces upstream and downstream of WWTP effluent sites at nine rivers in Illinois, United States. Microplastic concentration was higher downstream of WWTP effluent outfall sites in all but two rivers. Pellets, fibers, and fragments were the dominant microplastic types, and polymers were identified as polypropylene, polyethylene, and polystyrene. Mean microplastic flux was 1,338,757 pieces per day, although the flux was highly variable among nine sites (min = 15,520 per day, max = 4,721,709 per day). High-throughput sequencing of 16S rRNA genes showed bacterial assemblage composition was significantly different among microplastic, seston, and water column substrates. Microplastic bacterial assemblages had lower taxon richness, diversity, and evenness than those on other substrates, and microplastic selected for taxa that may degrade plastic polymers (e.g., Pseudomonas) and those representing common human intestinal pathogens (e.g., Arcobacter). Effluent from WWTPs in rivers is an important component of the global plastic “life cycle,” and microplastic serves as a novel substrate that selects and transports distinct bacterial assemblages in urban rivers. Rates of microplastic deposition, consumption by stream biota, and the metabolic capacity of microplastic biofilms in rivers are unknown and merit further research
Mechanistically-guided materials chemistry: synthesis of new ternary nitrides, CaZrN and CaHfN
Recent computational studies have predicted many new ternary nitrides,
revealing synthetic opportunities in this underexplored phase space. However,
synthesizing new ternary nitrides is difficult, in part because intermediate
and product phases often have high cohesive energies that inhibit diffusion.
Here, we report the synthesis of two new phases, calcium zirconium nitride
(CaZrN) and calcium hafnium nitride (CaHfN), by solid state metathesis
reactions between CaN and Cl ( = Zr, Hf). Although the
reaction nominally proceeds to the target phases in a 1:1 ratio of the
precursors via CaN + Cl CaN + 2 CaCl,
reactions prepared this way result in Ca-poor materials (CaN,
). A small excess of CaN (ca. 20 mol\%) is needed to yield
stoichiometric CaN, as confirmed by high-resolution synchrotron powder
X-ray diffraction. In situ synchrotron X-ray diffraction studies reveal that
nominally stoichiometric reactions produce Zr intermediates early in the
reaction pathway, and the excess CaN is needed to reoxidize Zr
intermediates back to the Zr oxidation state of CaZrN. Analysis of
computationally-derived chemical potential diagrams rationalizes this synthetic
approach and its contrast from the synthesis of MgZrN. These findings
additionally highlight the utility of in situ diffraction studies and
computational thermochemistry to provide mechanistic guidance for synthesis
Ajustes de quadrado médio do erro em ensaios de competição de cultivares de milho pelo método de Papadakis
Spatial dependence and experimental precision in snap bean ( Phaseolus vulgaris L.) trials related to the number of plants and harvests
Interfacial and Hydrodynamic Behavior of Thin Spherical Bubbles of Smectic Liquid Crystal in Microgravity
The Observation and Analysis of Smectic Islands in Space (OASIS) project comprises a series of experiments that probe the interfacial and hydrodynamic behavior of thin spherical bubbles of smectic liquid crystal in microgravity. Smectic films are the thinnest known structures formed of condensed phases, making them ideal for studies of two-dimensional (2D) coarsening dynamics and thermocapillary phenomena. The OASIS flight hardware was launched on SpaceX-6 in April 2015 and experiments were carried out on the International Space Station using four different smectic A and C liquid crystal materials in separate sample chambers. We will describe the behavior of collective island dynamics on the bubbles, including temperature-gradient-induced thermomigration, 2D Rayleigh-Plateau Instability, Oswald ripening dynamics, the single and multiple island diffusion on the curved surface and coalescence-driven coarsening dynamics of island emulsions in microgravity. On Earth, such island emulsions would rapidly sediment to the bottom of the bubble and coalesce, but in microgravity, coarsening of the emulsion can be observed free of gravitational effects
Ways of Asking, Ways of Telling: A Methodological Comparison of Ethnographic and Research Diagnostic Interviews
The interpretive understanding that can be derived from interviews is highly influenced by methods of data collection, be they structured or semistructured, ethnographic, clinical, life-history or survey interviews. This article responds to calls for research into the interview process by analyzing data produced by two distinctly different types of interview, a semistructured ethnographic interview and the Structured Clinical Interview for DSM, conducted with participants in the Navajo Healing Project. We examine how the two interview genres shape the context of researcher-respondent interaction and, in turn, influence how patients articulate their lives and their experience in terms of illness, causality, social environment, temporality and self/identity. We discuss the manner in which the two interviews impose narrative constraints on interviewers and respondents, with significant implications for understanding the jointly constructed nature of the interview process. The argument demonstrates both divergence and complementarity in the construction of knowledge by means of these interviewing methods
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