3,205 research outputs found

    Topochemical distribution of lignin and hydroxycinnamic acids in sugar-cane cell walls and its correlation with the enzymatic hydrolysis of polysaccharides

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    <p>Abstract</p> <p>Background</p> <p>Lignin and hemicelluloses are the major components limiting enzyme infiltration into cell walls. Determination of the topochemical distribution of lignin and aromatics in sugar cane might provide important data on the recalcitrance of specific cells. We used cellular ultraviolet (UV) microspectrophotometry (UMSP) to topochemically detect lignin and hydroxycinnamic acids in individual fiber, vessel and parenchyma cell walls of untreated and chlorite-treated sugar cane. Internodes, presenting typical vascular bundles and sucrose-storing parenchyma cells, were divided into rind and pith fractions.</p> <p>Results</p> <p>Vascular bundles were more abundant in the rind, whereas parenchyma cells predominated in the pith region. UV measurements of untreated fiber cell walls gave absorbance spectra typical of grass lignin, with a band at 278 nm and a pronounced shoulder at 315 nm, assigned to the presence of hydroxycinnamic acids linked to lignin and/or to arabino-methylglucurono-xylans. The cell walls of vessels had the highest level of lignification, followed by those of fibers and parenchyma. Pith parenchyma cell walls were characterized by very low absorbance values at 278 nm; however, a distinct peak at 315 nm indicated that pith parenchyma cells are not extensively lignified, but contain significant amounts of hydroxycinnamic acids. Cellular UV image profiles scanned with an absorbance intensity maximum of 278 nm identified the pattern of lignin distribution in the individual cell walls, with the highest concentration occurring in the middle lamella and cell corners. Chlorite treatment caused a rapid removal of hydroxycinnamic acids from parenchyma cell walls, whereas the thicker fiber cell walls were delignified only after a long treatment duration (4 hours). Untreated pith samples were promptly hydrolyzed by cellulases, reaching 63% of cellulose conversion after 72 hours of hydrolysis, whereas untreated rind samples achieved only 20% hydrolyzation.</p> <p>Conclusion</p> <p>The low recalcitrance of pith cells correlated with the low UV-absorbance values seen in parenchyma cells. Chlorite treatment of pith cells did not enhance cellulose conversion. By contrast, application of the same treatment to rind cells led to significant removal of hydroxycinnamic acids and lignin, resulting in marked enhancement of cellulose conversion by cellulases.</p

    Does community deprivation determine longevity after the age of 75? A cross-national analysis

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    Objectives: Analyze the association between socioeconomic deprivation and old-age survival in Europe, and investigate whether it varies by country and gender. Methods: Our study incorporated five countries (Portugal, Spain, France, Italy, and England). A 10-year survival rate expressing the proportion of population aged 75–84 years who reached 85–94 years old was calculated at area-level for 2001–11. To estimate associations, we used Bayesian spatial models and a transnational measure of deprivation. Attributable/prevention fractions were calculated. Results: Overall, there was a significant association between deprivation and survival in both genders. In England that association was stronger, following a dose–response relation. Although lesser in magnitude, significant associations were observed in Spain and Italy, whereas in France and Portugal these were even weaker. The elimination of socioeconomic differences between areas would increase survival by 7.1%, and even a small reduction in socioeconomic differences would lead to a 1.6% increase. Conclusions: Socioeconomic deprivation was associated with survival among older adults at ecological-level, although with varying magnitude across countries. Reasons for such cross-country differences should be sought. Our results emphasize the importance of reducing socioeconomic differences between areas.This work was supported by Portuguese funds through FCT—Fundação para a Ciência e a Tecnologia in the framework of project UID/BIM/04293/2013. AIR and MFP would also like to thank to FC—Fundação para a Ciência e a Tecnologia for the Grants PTDC/SAU-EPI/113424/2009 and SFRH/BD/82529/2011. MSC was supported by CNpQ (309692/2013-0) and FAPERJ (E-26/203.557/2014).We are very grateful to the National Statistic Offices for sending us the required data and to all the members of the European Deprivation Index (EDI) team. The authors would like to thank Rogério Ribeiro for the help in preparing visual supports, Alexandra Guttentag for her work as language editor, and the anonymous reviewers for their highly valuable corrections and suggestions

    Productionof poly(L-CO-D,L LacticAcid) porous fibers by electrospinning

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    The production of porous scaffolds has been widely investigated by the scientific community due to its suitability for tissue engineering. Among techniques that allow the fabrication of porous materials, electrospinning is appealing for being robust and versatile. This research investigated the pore formation in poly (L-co-D,L lactic acid) fibers obtained by conventional electrospinning and the influence of chloroform as a single solvent on fiber morphology. Random and highly porous fibers with a mean diameter of 2.373 ± 0.564 µm were collected. Chloroform affects the fiber morphology, mainly for its fast evaporation and low density of charges. The solvent on the surface evaporates quickly, and the low stretch of the jet does not help the polymer to reorganize over the length of the fiber, forming pores. In conclusion, the low dielectric constant and boiling point of chloroform induce pores formation along the PLDLA fibers.

    Distance to parks and non-residential destinations influences physical activity of older people, but crime doesn’t: a cross-sectional study in a southern European city

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    Background: Physical activity (PA) has numerous health benefits, but older adults live mostly sedentary lifestyles. The physical and social neighborhood environment may encourage/dissuade PA. In particular, neighborhood crime may lead to feeling unsafe and affect older adults’ willingness to be physically active. Yet, research on this topic is still inconclusive. Older population, probably the age group most influenced by the neighborhood environment, has been understudied, especially in Southern Europe. In this study, we aimed to analyze the association between leisure-time physical activity (LTPA) in older adults and objective crime, alongside other neighborhood characteristics. Methods: We obtained data from a population-based cohort from Porto (2005–2008) to assess LTPA. Only adults aged 65 years or more were included (n = 532). A Geographic Information System was used to measure neighborhood characteristics. Neighborhood crime was expressed as crime rates by category (incivilities, criminal offenses with and without violence and traffic crime). Neighborhood characteristics such as socioeconomic deprivation, land gradient, street density, transportation network, distance to parks, non-residential destinations and sport spaces were also included. Generalized Additive Models were fitted to estimate the association between neighborhood characteristics and the participation (being active vs. inactive) and frequency (min/day) of LTPA. Results: Forty-six percent of the men and 61 % of the women did not engage in any kind of LTPA. Among the active participants, men spent on average 50.5 (35.2 Standard Deviation, SD) min/day in LTPA, whereas the average among women was 36.9 (35.1 SD) min/day (p < 0.001). Neighborhood crime was unrelated to the participation in, or frequency of, LTPA. On the other hand, two neighborhood characteristics – distance to the nearest park (β = −0.0262, p = 0.029) and to the nearest non-residential destination (β = −0.0735, p = 0.019) – were associated with time spent on LTPA, but only among active older women. No neighborhood characteristic was related to participation in LTPA. Conclusions: From a public health point of view, the provision of parks and non-residential destinations (shops, schools, cultural and worship places) might contribute to elevate PA levels of already active older women. On the other hand, in this setting, crime was not a big issue

    A Factorization Law for Entanglement Decay

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    We present a simple and general factorization law for quantum systems shared by two parties, which describes the time evolution of entanglement upon passage of either component through an arbitrary noisy channel. The robustness of entanglement-based quantum information processing protocols is thus easily and fully characterized by a single quantity.Comment: 4 pages, 5 figure

    Augmented plasma microparticles during acute Plasmodium vivax infection

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    Background: In the last few years, the study of microparticles (MPs) - submicron vesicles released from cells upon activation or apoptosis - has gained growing interest in the field of inflammation and in infectious diseases. Their role in the human malaria parasite Plasmodium vivax remains unexplored. Because acute vivax malaria has been related to pro-inflammatory responses, the main hypothesis investigated in this study was that Plasmodium vivax infection is associated with elevated levels of circulating MPs, which may play a role during acute disease in nonimmune patients. Methods: Plasma MPs were analysed among thirty-seven uncomplicated P. vivax infections from an area of unstable malaria transmission in the Brazilian Amazon. The MP phenotype was analysed by flow cytometry using the classical MP marker, annexin, and fluorochrome-labeled monoclonal antibodies against specific cell surface markers. The frequencies of plasma MPs in P. vivax patients (n = 37) were further compared to malaria-unexposed controls (n = 15) and ovarian carcinoma patients (n = 12), a known MPs-inducing disease non-related to malaria. Results: The frequencies of plasma circulating MPs were markedly increased in P. vivax patients, as compared to healthy age-matched malaria-unexposed controls. Although platelets, erythrocytes and leukocytes were the main cellular sources of MPs during vivax malaria, platelet derived-MPs (PMPs) increased in a linear fashion with the presence of fever at the time of blood collection (b = 0.06, p < 0.0001) and length of acute symptoms (b = 0.36, p < 0.0001). Finally, the results suggest that plasma levels of PMPs diminish as patient experience more episodes of clinical malaria (b = 0.07, p < 0.003). Conclusions: Abundant circulating MPs are present during acute P. vivax infection, and platelet derived-MPs may play a role on the acute inflammatory symptoms of malaria vivax

    Chemical composition and enzymatic digestibility of sugarcane clones selected for varied lignin content

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    <p>Abstract</p> <p>Background</p> <p>The recalcitrance of lignocellulosic materials is a major limitation for their conversion into fermentable sugars. Lignin depletion in new cultivars or transgenic plants has been identified as a way to diminish this recalcitrance. In this study, we assessed the success of a sugarcane breeding program in selecting sugarcane plants with low lignin content, and report the chemical composition and agronomic characteristics of eleven experimental hybrids and two reference samples. The enzymatic digestion of untreated and chemically delignified samples was evaluated to advance the performance of the sugarcane residue (bagasse) in cellulosic-ethanol production processes.</p> <p>Results</p> <p>The ranges for the percentages of glucan, hemicellulose, lignin, and extractive (based on oven-dry biomass) of the experimental hybrids and reference samples were 38% to 43%, 25% to 32%, 17% to 24%, and 1.6% to 7.5%, respectively. The samples with the smallest amounts of lignin did not produce the largest amounts of total polysaccharides. Instead, a variable increase in the mass of a number of components, including extractives, seemed to compensate for the reduction in lignin content. Hydroxycinnamic acids accounted for a significant part of the aromatic compounds in the samples, with <it>p</it>-coumaric acid predominating, whereas ferulic acid was present only in low amounts. Hydroxycinnamic acids with ester linkage to the hemicelluloses varied from 2.3% to 3.6%. The percentage of total hydroxycinnamic acids (including the fraction linked to lignin through ether linkages) varied from 5.0% to 9.2%, and correlated to some extent with the lignin content. These clones released up to 31% of glucose after 72 hours of digestion with commercial cellulases, whereas chemically delignified samples led to cellulose conversion values of more than 80%. However, plants with lower lignin content required less delignification to reach higher efficiencies of cellulose conversion during the enzymatic treatment.</p> <p>Conclusion</p> <p>Some of the experimental sugarcane hybrids did have the combined characteristics of high biomass and high sucrose production with low lignin content. Conversion of glucan to glucose by commercial cellulases was increased in the samples with low lignin content. Chemical delignification further increased the cellulose conversion to values of more than 80%. Thus, plants with lower lignin content required less delignification to reach higher efficiencies of cellulose conversion during the enzymatic treatment.</p

    Effect of the presence of surfactant and ionic liquids on the esterification of oleic acid catalyzed by immobilized lipase

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    Ionic liquids (ILs) and surfactants are widely used in order to increase the catalytic efficiency of lipases. In this sense, the present study aimed to evaluate the potential of different ionic liquids (C4MIM.Ac, C4MIM.HSO4, C4MIM.TF2N, C4MIM.BF4, C12MIM.I, and C12MIM.Cl), Aliquat 336 and di-2-ethylhexyl sodium sulfosuccinate (AOT) as adjuvants in the esterification of oleic acid with different alcohols catalyzed by Novozyme 435. First of all, it evaluates the effect of alkyl chain length of the alcohol and the positioning of the hydroxyl group. The selection of additives, made with isopropyl alcohol, pointed AOT and C4MIM.Ac as adjuvants effective on the potential of esterification of the enzyme (an increase of 35% in the potential of esterification). Using methanol, ethanol and 3-methyl-1-butanol, the C4MIM.Ac was proven not to be efficient, while the AOT shows adjuvant effect in the esterification of oleic acid with methanol (increasing in catalytic efficiency of enzyme in 21%).Key words: Esterification, di-2-ethylhexyl sodium sulfosuccinate (AOT), Ionic Liquids, Novozyme 435
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