1,243 research outputs found

    Discovery, cloning, and analysis of novel fluorescent proteins from various color morphs of Corynactis californica

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    Although the number of fluorescent protein (FP) genes cloned from the GFP family continues to increase, few studies of GFP-type pigments in non-bioluminescent, non-symbiotic organisms have been attempted. The first goal of this study was to locate, clone, characterize, and analyze fluorescent proteins from an organism exhibiting these traits in order to better understand their evolution and function. I successfully cloned two full-length GFP homologs by applying a FACS-based screening method to a cDNA library constructed from a temperate corallimorpharian, Corynactis californica. The full-length coding regions of each gene were subcloned into an expression vector and bacterial cultures were used to express the proteins. Spectral properties of purified proteins were characterized and chromophore maturation behavior was examined. Phylogenetic methods were also used to analyze the new gene sequences in relation to homologous GFP family members. After discovering two GFP-like proteins in a single red morph, I investigated six additional morphs of Corynactis californica, and found indications of a variety of fluorescent pigments based on fluorescence emission spectra from live specimens. The second goal of this study was to identify and describe the variation in fluorescent pigments among morphs of C. californica and to relate the in vivo emission patterns and colors to FP genes cloned from and expressed in each morph. Specifically, I found that all morphs express a similar suite of GFP-like proteins, generated by at least three to four genetic loci, which code for three colors: green, orange, and red. The genes exhibit tissue-specific expression patterns that differ by morph, and two major expression patterns emerged. Sequence and phylogenetic analyses comparing the new FP genes from C. californica to one another and to homologous members of the GFP family indicate that FP genes from this species are most closely related to one another, but that FP genes arose in an ancestor to the Anthozoa before speciation events separating anthozoan subclasses, including the Corallimorpharia. Possible ecological roles of variations in fluorescent pigmentation among morphs of C. californica are also discussed

    Evaluation of Recent Upgrades to the NESS (Nuclear Engine System Simulation) Code

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    The Nuclear Thermal Rocket (NTR) concept is being evaluated as a potential propulsion technology for exploratory expeditions to the moon, Mars, and beyond. The need for exceptional propulsion system performance in these missions has been documented in numerous studies, and was the primary focus of a considerable effort undertaken during the Rover/NERVA program from 1955 to 1973. The NASA Glenn Research Center is leveraging this past NTR investment in their vehicle concepts and mission analysis studies with the aid of the Nuclear Engine System Simulation (NESS) code. This paper presents the additional capabilities and upgrades made to this code in order to perform higher fidelity NTR propulsion system analysis and design, and a comparison of its results to the Small Nuclear Rocket Engine (SNRE) design

    A Comparison of Materials Issues for Cermet and Graphite-Based NTP Fuels

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    This paper compares material issues for cermet and graphite fuel elements. In particular, two issues in NTP fuel element performance are considered here: ductile to brittle transition in relation to crack propagation, and orificing individual coolant channels in fuel elements. Their relevance to fuel element performance is supported by considering material properties, experimental data, and results from multidisciplinary fluid/thermal/structural simulations. Ductile to brittle transition results in a fuel element region prone to brittle fracture under stress, while outside this region, stresses lead to deformation and resilience under stress. Poor coolant distribution between fuel element channels can increase stresses in certain channels. NERVA fuel element experimental results are consistent with this interpretation. An understanding of these mechanisms will help interpret fuel element testing results

    Multidisciplinary Simulation of Graphite-Composite and Cermet Fuel Elements for NTP Point of Departure Designs

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    This paper compares the expected performance of two Nuclear Thermal Propulsion fuel types. High fidelity, fluid/thermal/structural + neutronic simulations help predict the performance of graphite-composite and cermet fuel types from point of departure engine designs from the Nuclear Thermal Propulsion project. Materials and nuclear reactivity issues are reviewed for each fuel type. Thermal/structural simulations predict thermal stresses in the fuel and thermal expansion mis-match stresses in the coatings. Fluid/thermal/structural/neutronic simulations provide predictions for full fuel elements. Although NTP engines will utilize many existing chemical engine components and technologies, nuclear fuel elements are a less developed engine component and introduce design uncertainty. Consequently, these fuel element simulations provide important insights into NTP engine performance

    Field evaluation of the efficacy and safety of a combination of spinosad and milbemycin oxime in the treatment and prevention of naturally acquired flea infestations and treatment of intestinal nematode infections in dogs in Europe

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    AbstractTwo separate randomised, blinded, multicentre field trials were conducted to evaluate the efficacy and safety of a combination of spinosad and milbemycin oxime (MO) (Trifexis®, Elanco Animal Health) in the treatment and prevention of naturally acquired flea infestations and intestinal nematode infections in European dogs. Treatments using Trifexis® and each control veterinary product (CVP) were administered once on Day 0 in both field studies.In the flea field trial, 11 veterinary clinics in France participated in the study. On Day 0, whole body flea comb counts were conducted on all dogs being evaluated for enrolment. Dogs with ≥7 fleas on Day 0 were enrolled, treated once on Day 0 with spinosad/MO or the CVP (Stronghold®; selamectin) and then underwent post-treatment flea counts on Days 14 and 30. There were 150 spinosad/MO treated dogs and 71 CVP treated dogs included in the flea effectiveness population. Effectiveness against fleas (% reduction in geometric means; GM) was 98.97% and 97.37% for the spinosad/MO treated dogs, and 97.43% and 93.96% for the CVP dogs on Days 14 and 30, respectively, compared to the pre-treatment baseline flea counts. Of the spinosad/MO dogs, 89.3% and 80.0% had no live fleas on Days 14 and 30, compared to 77.5% and 70.4% of the CVP dogs, respectively.In the nematode field trial, data from 10 veterinary clinics in France and 19 in Ireland were pooled. Faecal samples from dogs at each clinic were analysed. A positive result at screening (parasite eggs from Toxocara canis, Toxascaris leonina, Trichuris vulpis or Ancylostoma caninum) allowed for enrolment. Dogs were randomised to spinosad/MO or the CVP (Milbemax®; MO/praziquantel). On Day 8, a post-treatment faecal sample was taken and analysed. Of 2333 dogs screened for nematode eggs, 238 dogs were positive with one or more of these nematodes, and 229 were enrolled in the study. Of the 229 dogs, 151 were treated with a single dose of spinosad/MO, and 77 were treated with a single dose of CVP. Post-treatment effectiveness against all nematodes (% reduction GM) was achieved with reductions of 98.57% and 97.57% for the spinosad/MO treated dogs and CVP dogs, respectively, as compared to the pre-treatment baseline faecal egg counts.Trifexis® was shown to be safe and effective against natural infestations of fleas as well as mixed and single intestinal nematode infections in client owned dogs in Europe when administered as a single oral administration at the recommended dose

    Revised Point of Departure Design Options for Nuclear Thermal Propulsion

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    In an effort to further refine potential point of departure nuclear thermal rocket engine designs, four proposed engine designs representing two thrust classes and utilizing two different fuel matrix types are designed and analyzed from both a neutronics and thermodynamic cycle perspective. Two of these nuclear rocket engine designs employ a tungsten and uranium dioxide cermet (ceramic-metal) fuel with a prismatic geometry based on the ANL-200 and the GE-710, while the other two designs utilize uranium-zirconium-carbide in a graphite composite fuel and a prismatic fuel element geometry developed during the Rover/NERVA Programs. Two engines are analyzed for each fuel type, a small criticality limited design and a 111 kN (25 klbf) thrust class engine design, which has been the focus of numerous manned mission studies, including NASA's Design Reference Architecture 5.0. slightly higher T/W ratios, but they required substantially more 235U

    TG-DTA and DSC investigations of ''pinhão'' starch modified by calcium hypochlorite and UV light.

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    Starches, when in its native forms, usually do not have the characteristics required for industrial processing. ''Pinhão'', a seed from the Araucaria angustifolia tree, has starch as main presenting as a great alternative source of starch. Samples of native ''pinhão'' starch were treated with standard calcium hypochlorite solutions (0.1, 0.2 and 0.5 mol L-1) and exposed for one hour under UV light. The modification process applied altered the thermal behavior of the ''pinhão'' starch as the TGA-DTA and DSC results presented.Edição dos Anais do 7º Simpósio de Análise Térmica, 2015, Bauru

    Caracterização de amido de pinhão modificado com soluções de ácido clorídrico 0,1 e 0,2M em presença de etanol e metanol.

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    O amido de pinhão possui propriedades interessantes, porém pouco foi estudado até o momento. Proveniente do Sul do Brasil, a semente da Araucária angustifolia serve de alimento para diversas culturas da região. Os amidos nativos de diversas fontes botânicas possuem características de interesse industrial, porém algumas só são adquiridas ou melhoradas mediante a aplicação de agentes que modifiquem as estruturas originais dos grânulos, como ácidos e oxidantes. O presente trabalho teve como objetivo estudar propriedades do amido de pinhão nativo e este modificado, utilizando ácido clorídrico 0,1M e 0,2M, em meio etanólico e metanólico. Pelas curvas DSC foi possível determinar as temperaturas ?onset?, de pico e de conclusão do processo de gelatinização das amostras, além de se determinar a entalpia envolvida no processo. Pelas imagens NC-AFM pode-se medir o tamanho dos grânulos dos amidos e a rugosidade dos mesmos antes e após as modificações. Por meio da técnica TG-DTG, foi possível observar um perfil de perda de massa semelhante para todas as amostras, com 3 etapas definidas, sendo a 1ª referente à desidratação da amostra e a 2ª e 3ª referente à decomposição da matéria orgânica à cinzas. Através da análise de propriedade de pasta (RVA) se observou o perfil reológico das amostras, podendo determinar temperatura de pico, viscosidade final e retrogradação.CBRATEC
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