621 research outputs found
Teaching scientific terminology in foreign language improves the performance of undergraduate medical students
M-U-N-I: Evidencing the Inadequacies of the Municipal Securities Regulatory Framework
This article argues that the current regulation of the minicipal securities market is inadequate, and that regulatory reform is not only necessary but also permissible as the Securities and Exchange Commission has the legal authority under the current statutory framework to substantially remedy such inadequacy. In making this argument, this article focuses on the legislative history of the Securities Reform Act of 1975, analyses of statutory text, the current regulatory framework surrounding the municipal securities market, prior attempts to effect regulatory reform, and one of the principal issues with the current regulatory framework - the lack of uniform accounting principles in the financial statements municpal issuers use when issuing new securities. In addressing these topics, this article uses different lenses (macro, meso, and micro) to, hopefully, deliver a more compelling tale with three underlying themes: The Dangers of Function Following Form, The Dangers of Circuitous Regulation and Concision, and The Causality Dilemma
Cuba for Cubans? Contradictions in Cuban Development Since 1990
Not long ago, eighty-five percent of Cuban trade was conducted through the the Soviet Union\u27s Council of Mutual Economic Assistance and the US maintained a strict economic embargo. Today, most Cuban trade is conducted with countries as diverse as Venezuela, China, and Canada, and despite the economic embargo, the US is the largest source of food for Cuba. The fall of the USSR in the early 90s forced Cuba into restructuring its trade, with widespread repercussions throughout Cuban economic, political and social systems and the ideology behind them. World-systems theory offers a theoretical framework that allows an understanding of the transition of Cuban society within an international, national, and ideological context. Contradictions in key areas of Cuban policy are specific manifestations of general contradictions in the capitalist world-economy
Catalytic upgrading of fast pyrolysis bio-oils applying nickel-based catalysts
Motivated by the population growth, climate change and limited fossil fuel resources, renewable alternatives for fuels and chemicals production are becoming more and more important. Biomass, especially residual lignocellulosic biomass shows a significant potential as feedstock for bioenergy, due to its high carbon content and short-term availability. Among the thermochemical conversion technologies, fast pyrolysis for biomass liquefaction can be considered already well stablished, as several commercial plants are spread worldwide. However, fast pyrolysis bio-oil, the main product of fast pyrolysis, currently shows limited bioenergy application as boiler fuel for heat production. It can be explained by its chemical composition and properties, as fast pyrolysis bio-oil is an acidic multi-component product, with low energetic density due to its high content of water and oxygenated compounds. Moreover, wood is the only feedstock currently used commercially.
In order to expand the feedstock range and application viability, an additional upgrading treatment may be required in order to improve the fast pyrolysis properties, meeting existing fuel standards. In order to do so, catalytic hydrotreatment is considered a promising upgrading treatment, as it is a well-known technology currently applied in petroleum refineries for heteroatoms removal from crude oil. However, due to the differences in chemical composition, the hydrotreatment conditions applied to crude oil cannot be simply applied to fast pyrolysis bio oil. Although research in this field has been carried out for a few decades, there are still open questions to enable hydrotreatment to produce fuel oils from residual biomass in stable processes. By developing a robust fast pyrolysis bio-oil hydrotreatment process, small biorefineries units could be installed near to feedstock sourcing or even be installed in biorefinery units already stablished, such as a sugarcane biorefinery, in which high volumes of residual biomass are generated. Also, co-processing of crude oil and fast pyrolysis bio-oil in petroleum refineries may be a feasible option.
In view of the importance of the hydrotreatment for expansion of the range of chemicals obtained by thermochemical conversion of residual biomass, the presented work investigated the hydrotreatment of fast pyrolysis bio-oil applying nickel-based catalysts. In a systematic evaluation nickel-based catalysts with different metal loading, supports and promoters have been studied. Overall, six nickel-based catalyst were screened and compared to ruthenium supported in activated carbon. The hydrotreatment conditions in terms of reaction time, temperature and pressure were optimized and fast pyrolysis bio-oils derived from beech wood and residual biomass (sugarcane bagasse) were hydrotreated. Additionally, the heavy phase separated from beech wood bio-oil, characterized by its high content of lignin-derived compounds, was hydrotreated. The effect of deactivation by sulphur on the hydrotreatment was investigated by use of model substances in a continuously operated trickle bed reactor, since with this reactor the deactivation can be observed depending on time (in contrast to batch experiments). Finally, a 2 step upgrading approach of a previously upgraded fast pyrolysis bio-oil was proposed and verified.
Initially two high loaded nickel-based catalysts (monometallic nickel and nickel chromium) were evaluated in comparison to Ru/C by batch hydrotreatment of beech wood bio-oil at 80 bar, 4 h, 175 °C and 225 °C. Both nickel-based catalysts revealed similar hydrodeoxygenation activities for the conditions applied and the nickel catalysts showed the higher hydrogenation activity compared to Ru/C. The nickel-chromium catalyst demonstrated the highest activity for conversion of organic acids, ketones and sugars, attributed to the strength of the acid sites promoted by chromium oxide. When applied in a second hydrotreatment step of a previously upgraded oil, the oxygen content of the oil was reduced by 64.8 % in comparison to the original feedstock while the water concentration was reduced by 90 %. Nearly 96 % of the organic acids were converted and the higher heating value was increased by 90.1 %. Despite nickel-chromium demonstrated the best activity in the one step hydrotreatment reactions and contributed significantly in the 2-step upgrading, the oxygen content of 25.3 wt.% dry basis in the upgraded oil was still considered high. Thus, the upgrading conditions were further optimized, aiming to achieve higher hydrodeoxygenation performance.
The conditions of batch hydrotreatment were optimized with nickel-chromium catalyst considering two pressures (80 and 100 bar), four temperatures (175 °C, 225 °C, 275 °C and 325 °C), for both the complete beech wood fast pyrolysis bio-oil, as well as for the heavy phase after spontaneous separation induced by intentional ageing of the bio-oil. At higher temperatures, increased hydrodeoxygenation levels were reached, while at higher pressure larger hydrogen consumption was observed with no significant influence on hydrodeoxygenation. The best conditions among all tested was obtained by hydrotreating the beech wood bio-oil at 325 °C and 80 bar; in this case, 43 % of hydrodeoxygenation was reached. Although improved hydrodeoxygenation activity observed with nickel-chromium at optimized conditions, the results motivated the synthesis and evaluation of new nickel-based catalysts, targeting higher deoxygenation levels.
In the next part of this study, four nickel-based catalyst were synthesized by wet impregnation and evaluated for the hydrotreatment of beech wood fast pyrolysis bio-oil. The catalysts were supported in silica and zirconia and the influence of copper as promoter was studied. Among them, nickel-silica was the most active for hydrodeoxygenation, reducing the oxygen content of the upgraded beech wood fast pyrolysis bio-oil by more than 50 %. The highest degree of water removal as well as low gas and char production were also considered good properties attributed to this catalyst. The investigation on repeated cycles of hydrotreatment with the same catalyst showed a remaining activity even after the fourth reuse, in which 43 % of oxygen was removed. Thus, based on the results obtained with Ni/SiO2, this catalyst was selected together with nickel-chromium catalyst to be used for hydrotreatment of fast pyrolysis bio-oil from residual biomass, as until this point the study had considered only wood-based fast pyrolysis bio oil.
Based on the studies so far, the integration of hydrotreatment into a thermochemical conversion route of residues in a sugarcane refinery was proposed. For that, the study encompassed sugarcane bagasse characterization, fast pyrolysis and hydrotreatment of the so derived bio-oils with nickel-chromium and nickel-silica catalyst. The detailed investigation of the bagasse and the fast pyrolysis bio-oil compositions allowed the correlation of the biomass building blocks with the monomers obtained. The hydrotreatment showed that nickel-chromium showed highest activity for organic acids conversion, as previously observed with beech wood bio-oil, whereas nickel-silica revealed more active for conversion of aromatics. Hydrodeoxygenation of 43.3 % was obtained with nickel-silica. Although both catalysts demonstrated to be active at the conditions evaluated, the high viscosities of the upgraded oils in comparison to those obtained from fast pyrolysis showed that polymerization took place and must be further investigated in detail, as it is one of the limiting factors for further application of fast pyrolysis bio-oil hydrotreatment. Overall, this studied showed to be very promising and future studies are planned.
In the final part of the thesis, both high loaded nickel-based catalysts studied in the first chapters were selected for a detailed investigation in a continuous operated tricked bed hydrotreatment reactor, due to the similar nickel concentration, nickel particle size and support. The selection of both catalysts aimed to investigate the influence of sulfur on long term catalyst deactivation and the role of chromium in catalyst deactivation. Both catalysts were active for conversion of model substances over more than 48 h of reaction time. By the presence of sulfur, the selectivity of both catalysts changed, mainly towards alkene formation, while the activity remained in the same range. Formation of Ni3S2 was observed for both catalysts, but the highest intensity in the diffraction peak of metallic nickel in the nickel-chromium catalyst might be an indication of higher resistance to sulfur poisoning in comparison to Ni catalyst. In general, the catalysts were active for the conditions tested, although the hydrogenation activity was compromised by sulfur poisoning.
Overall, all the catalysts tested in this study were active for hydrotreatment of fast pyrolysis bio-oils. If only stabilization of reactive compounds such as aldehydes and furfurals is required, all of them could be considered suitable candidates. In terms of hydrodeoxygenation activity, Ni/SiO2 showed the highest performance, while nickel-chromium showed to be the most active for conversion of organic acids and superior hydrogenation capacity than Ni/SiO2
EFFECT OF IRRIGATION AND HYBRIDS ON MICROBIAL POPULATION DYNAMICS IN THE RIZHOSPHERE OF OIL PALM (Elaeis guineensis Jacq.)
Objective:This research was carried out to evaluate the effect of irrigation and hybrids on the population dynamics of microorganisms associated with the rhizosphere of oil palm (Elaeis guineensis Jacq.).Methods:Plots were installed under irrigated and non-irrigated conditions using three hybrids (Dura x Pisifera) of oil palm. A split-plot design was used, with three replications. Samples of soil were extracted and processed to determine the populations of functional groups of heterotrophic bacteria, actinomycetes, fungi, phosphorus (P) solubilizing microorganisms, and vesicular arbuscular (VA) mycorrhizae. Samples were taken during the wet season (June) and the dry season (August).Results:No significant differences were detected for bacterial populations (heterotrophic and actinomycetes) for irrigation and hybrids. Populations recorded for heterotrophic bacteria when water stress accounted for 28cbs were 7.43×106 CFU/g (colony forming units per g of dry soil) in irrigated plots, versus 5.86×106 CFU/g in non-irrigated plots. Fungal populations were 4.49×103 CFU/g in irrigated plots, while in non-irrigated plots were 1.81×104 CFU/g. Mycorrhizae levels ranged between 13.6% and 21.9% in irrigated and non-irrigated plots respectively. The populations of P -solubilizing microorganisms ranged from 6.64×105 CFU/g in irrigated plots, to 2.91×104 CFU/g in plots without irrigation.Conclusions:Under the conditions of this study, in the oil palm rhizosphere, there were not significant differences between the bacterial populations (heterotrophs and actinomycetes) for irrigation and hybrids. Under the same conditions, significant differences were found among fungal populations, P-solubilizing microorganisms, and VA mycorrhizae, in the irrigation factor. The major bacterial populations were recorded in the rainy season 7centibars (cbs); meanwhile, the higher fungal populations were recorded in the dry season (28cbs). Hybrids not exert major influence on microbial populations under the conditions of this study. With some of the microorganisms isolated in this study, starting tests are needed to identify potential bio – fertilizers, and / or bio – enhancers of soil properties. Keywords: VA mycorrhizae, Phosphorus -solubilizing microorganisms, Oil palm, Heterotrophs, Irrigatio
Triagem da potencial atividade antiviral de peptídeos antimicrobianos e da hemolinfa de ostras
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Programa de Pós-Graduação em Biotecnologia.Os produtos naturais constituem uma fonte inesgotável de compostos com atividades farmacológicas promissoras, incluindo ação antiviral. Os materiais protéicos são encontrados em abundância na natureza e têm atividades biológicas como antibacteriana, antifúngica, antitumoral e antiviral comprovadas. Neste trabalho, a citotoxicidade (CC50) e a atividade antiviral (CE50) de peptídeos antimicrobianos (PAM) e hemolinfa de ostras (Crassostrea gigas e C. rhizophorae), foram avaliadas, em células VERO, HEp-2 e MA104 e contra os vírus herpes simplex tipo 1(HSV-1/KOS), adenovírus sorotipo 5 (AdV-5), rotavírus símio SA-11 (RV-SA11), pelo ensaio colorimétrico do MTT, utilizando diferentes estratégias. Para a hemolinfa das ostras também foi realizado o estudo da ação virucida. Dentre os PAM testados, a peneidina apresentou o maior índice de seletividade (IS= CC50/ CE50) para o HSV-1/KOS (IS = 64). A hemolinfa de ostras apresentou ação virucida contra os três vírus avaliados neste estudo, também apresentando atividade anti-herpértica (IS = 19,76/C. rhizophorae) e antiadenovírus (IS = 5,33/C. gigas), sem, no entanto, exibir ação antiviral contra o rotavírus. Foram observados, em alguns casos, baixos IS, associados a altas porcentagens de inibição da replicação viral, mais evidente no grupo dos PAM. Estudos adicionais devem ser realizados a fim de se confirmar a atividade antiviral e prováveis mecanismos ação
In vitro characterization of a nanostructured fibrin agarose bio-artificial nerve substitute
"This is the peer reviewed version of the following article: Carriel, V., Scionti, G., Campos, F., Roda, O., Castro, B., Cornelissen, M., Garzón, I., and Alaminos, M. (2017) In vitro characterization of a nanostructured fibrin agarose bio-artificial nerve substitute. J Tissue Eng Regen Med, 11: 1412–1426., which has been published in final form at [10.1002/term.2039. . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."Neural tissue engineering is focused on the design of novel biocompatible substitutes to repair peripheral nerve injuries. In this paper we describe a nanostructured fibrin–agarose bioartificial nerve substitute (NFABNS), based on nanostructured fibrin–agarose hydrogels (FAHs) with human adipose-derived mesenchymal stem cells (HADMSCs). These NFABNSs were mechanically characterized and HADMSCs behaviour was evaluated using histological and ultrastructural techniques. Mechanical characterization showed that the NFABNSs were resistant, flexible and elastic, with a high deformation capability. Histological analyses carried out in vitro during 16 days revealed that the number of HADMSCs decreased over time, with a significant increase after 16 days. HADMSCs formed cell clusters and degraded the surrounding scaffold during this time; additionally, HADMSCs showed active cell proliferation and cytoskeletal remodelling, with a progressive synthesis of extracellular matrix molecules. Finally, this study demonstrated that it is possible to generate biologically active and mechanically stable tissue-like substitutes with specific dimensions, based on the use of HADMSCs, FAHs and a nanostructure technique. However, in vivo analyses are needed to demonstrate their potential usefulness in peripheral nerve repairPeer ReviewedPostprint (author's final draft
SYMPHYLIDS IN ROSES OF ECUADOR
Flowers are considered the first non- traditional export product in Ecuador.Aphids and mites are the most common arthropod pests on roses.  Little is known about the effect of myriapod-like animals on rose production. Individuals with oval-shaped head, Long filiform-like antennae and 3 to 3.5 millimeters in size were detected in commercial flower greenhouses of Ecuador.  Although the incidence of the pest was very low, there was a high level of infestation in the spot of soil where the animals were detected.  More information is needed about the species of symphylids affecting rose plants in commercial greenhouses of Ecuador
Regenerative medicine in the secondary education curriculum in Spain : literacy in a new medical paradigm
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