417 research outputs found
Avaliação de óleos comestíveis comercializados no Rio de Janeiro.
Procedeu-se a um levantamento das condições dos óleos vegetais comestíveis comercializados no Rio de Janeiro, aliando-se determinações tradicionais à cromatografia de gás. Utilizaram-se óleos de soja, milho, caroço de algodão, oliva, arroz e mistos. Observaram-se discrepâncias na composição em ácidos graxos principalmente nos óleos de oliva, resultantes provavelmente de misturas com óleo de coco ou babaçu e com soja.bitstream/item/65434/1/CTAA-DOCUMENTOS-13-AVALIACAO-DE-OLEO-COMESTIVEIS-COMERCIALIZADOS-NO-RIO-DE-JANEIRO-FL-02165.pd
Transesterificação de óleos vegetais para fins combustíveis.
Amostras de óleos de soja, algodão, colza, girassol e amendoim, depois de refinação alcalina, foram submetidos à transesterificações com metanol e etanol. Observou-se que enquanto as reações com metanol ou etanol anidro p.a. se processam facilmente com altos rendimentos e recuperação quase total do glicerol, as reações com etanol anidro comercial são mais complicadas não havendo separação do glicerol, ocorrendo grandes perdas. Foi desenvolvido, na EMBRAPA-CTAA, um processo que permite a obtenção dos ésteres etílicos, com etanol anidro comercial com conversão quase completa dos triglicerídios e separação do glicerol por adição de uma certa quantidade de glicerol.bitstream/item/118260/1/transesterificacao-de-oleos-vegetais.pd
Transesterificação de óleo de soja com diversos catalisadores alcalinos.
Amostras de óleo de soja neutralizado e seco foram transesterificadas com etanol comercial a 99,5% na presença de quantidades equivalentes de hidróxido, metóxido, etóxido e gliceróxido de sódio como catalisadores. Com o uso dos três alcóxidos obteve-se a separação do glicerol formado durante a reação, o que não ocorreu com o uso de hidróxido de sódio. O rendimento de sódio, como catalisador na transesterificação, apresenta vantagens econômicas e tecnológicas quando comparado com o hidróxido de sódio.bitstream/item/65433/1/CTAA-DOCUMENTOS-12-TRANSESTERIFICACAO-DE-OLEO-DE-SOJA-COM-DIVERSOS-CATALISADORES-ALCALINOS-FL-021.pd
Deficiências minerais em pastagens do Estado do Rio de Janeiro.
bitstream/item/65349/1/CTAA-DOCUMENTOS-8-DEFICIENCIAS-MINERAIS-EM-PASTAGENS-DO-ESTADO-DO-RIO-DE-JANEIRO-FL-02171.pd
Óleos de macaúba: uma alternativa para a oleoquímica.
bitstream/item/118253/1/oleos-de-macauba.pd
Linear Contraction Behavior of Low-Carbon, Low-Alloy Steels During and After Solidification Using Real-Time Measurements
A technique for measuring the linear contraction during and after solidification of low-alloy steel was developed and used for examination of two commercial low-carbon and low-alloy steel grades. The effects of several experimental parameters on the contraction were studied. The solidification contraction behavior was described using the concept of rigidity in a solidifying alloy, evolution of the solid fraction, and the microstructure development during solidification. A correlation between the linear contraction properties in the solidification range and the hot crack susceptibility was proposed and used for the estimation of hot cracking susceptibility for two studied alloys and verified with the real casting practice. The technique allows estimation of the contraction coefficient of commercial steels in a wide range of temperatures and could be helpful for computer simulation and process optimization during continuous casting. © 2013 The Minerals, Metals & Materials Society and ASM International
Biophysics and systems biology
Biophysics at the systems level, as distinct from molecular biophysics, acquired its most famous paradigm in the work of Hodgkin and Huxley, who integrated their equations for the nerve impulse in 1952. Their approach has since been extended to other organs of the body, notably including the heart. The modern field of computational biology has expanded rapidly during the first decade of the twenty-first century and, through its contribution to what is now called systems biology, it is set to revise many of the fundamental principles of biology, including the relations between genotypes and phenotypes. Evolutionary theory, in particular, will require re-assessment. To succeed in this, computational and systems biology will need to develop the theoretical framework required to deal with multilevel interactions. While computational power is necessary, and is forthcoming, it is not sufficient. We will also require mathematical insight, perhaps of a nature we have not yet identified. This article is therefore also a challenge to mathematicians to develop such insights
Stellar populations of bulges at low redshift
This chapter summarizes our current understanding of the stellar population
properties of bulges and outlines important future research directions.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen
E., Peletier R., Gadotti D., Springer Publishing. 34 pages, 12 figure
The plight of the sense-making ape
This is a selective review of the published literature on object-choice tasks, where participants use directional cues to find hidden objects. This literature comprises the efforts of researchers to make sense of the sense-making capacities of our nearest living relatives. This chapter is written to highlight some nonsensical conclusions that frequently emerge from this research. The data suggest that when apes are given approximately the same sense-making opportunities as we provide our children, then they will easily make sense of our social signals. The ubiquity of nonsensical contemporary scientific claims to the effect that humans are essentially--or inherently--more capable than other great apes in the understanding of simple directional cues is, itself, a testament to the power of preconceived ideas on human perception
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