17,557 research outputs found

    Aprovechamiento energético e integrado por fraccionamiento de biomasa lignocelulósica forestal y agroindustrial

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    Se caracteriza la materia prima y las fases l√≠quidas de la autohidr√≥lisis de 5 materiales lignocelul√≥sicos: Eucalyptus globulus, Arundo donax, tallos de girasol (Helianthus annuus), tagasaste (Chamaecytisus proliferus) y Paulownia fortunei para evaluar su viabilidad para la obtenci√≥n de energ√≠a y otros productos qu√≠micos a trav√©s de un fraccionamiento integral v√≠a autohidr√≥lisis. En todos los casos se ha utilizado la planta completa sin hojas, frutas o ramillas y en el caso de los tallos de girasol, se han desmedulado. De entre los materiales estudiados, los tallos de girasol y el tagasaste presentan unos contenidos en holocelulosa (74,2% y 80,3%) mayores que el Eucalyptus globulus y unos contenidos en lignina menores (19,9% y 19,8%). Todas las materias primas superan al Eucalyptus globulus por su contenido en xilano (entre 18,3% y 23,9%) pero ninguna alcanza su valor de concentraci√≥n de glucano (46,8%). Existe un incremento en la solubilizaci√≥n de las hemicelulosas al aumentar la temperatura de la autohidr√≥lisis con unos √≥ptimos de extracci√≥n entre 185¬ļC y 195¬ļC para Arundo donax, tagasaste o Paulownia fortunei, temperatura inferior a la de las mejores condiciones de extracci√≥n de Eucalyptus globulus. Se obtienen elevados contenidos en olig√≥meros (tagasaste: 13,9%, tallos de girasol: 21,5%, Paulownia fortunei: 11,7%) respecto a Eucalyptus globulus (10,3% a 196¬ļC)._________________________________Five raw materials and liquors from autohydrolysis process were characterized: Eucalyptus globulus, Arundo donax, sunflower stalks (Helianthus annuus), tagasaste (Chamaecytisus proliferus) and Paulownia fortunei, for energy and others chemicals using autohydrolysis and integral fractionation. Tagasaste and sunflower stalks had holocellulose contents (74,2% and 80,3%) higher than holocellulose content from Eucalyptus globulus and lignin contents lower (19,9% y 19,8%) than lignin from Eucalyptus globulus. All raw materials had xylan contents (between 18,3% and 23,9%) and glucan contents higher and lower respectively than xylan and glucan from Eucalyptus globulus (glucane: 46,8%). Hemicelluloses solubilization were increased with autohydrolysis temperature. The optimal range was 185¬ļC to 195¬ļC for Arundo donax, tagasaste and Paulownia fortunei. This temperature is lower than better condition for Eucalyptus globulus. The oligosaccharides contents were high (tagasaste: 13,9%, sunflower stalks: 21,5%, Paulownia fortunei: 11,7%) with respect to Eucalyptus globulus (10,3% a 196¬ļC)

    Generation and analysis of an Eucalyptus globulus cDNA library constructed from seedlings subjected to low temperature conditions

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    Indexación: ScieloEucalyptus globulus is the most important commercial temperate hardwood in the world because of its wood properties and due to its characteristics for biofuel production. However, only a very low number of expressed sequence tags (ESTs) are publicly available for this tree species. We constructed a cDNA from E. globulus seedlings subjected to low temperature and sequenced 9,913 randomly selected clones, generating 8,737 curated ESTs. The assembly produced 1,062 contigs and 3,879 singletons forming a Eucalyptus unigene set. Based on BLASTX analysis, 89.3% of the contigs and 88.5% of the singletons had significant similarity to known genes in the non-redundant database of GenBank. The Eucalyptus unigene set generated is a valuable public resource that provides an initial model for genes and regulatory pathways involved in cell wall biosynthesis at low temperature.Financial support: This work was partially funded by Universidad Andrés Bello (DI Proyect: 04-05/1) and MIFAB (Proyect: P04-071-F) and by the Microsoft Joint Research Program

    Standardization of Eucalyptus globulus leaves and Cetraria islandica slan

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    The aim. The aim of this study was to propose methods of standardization of Eucalyptus globulus leaves and Cetraria islandica slan by the main group of biologically active substances (BAS). This was done for further development of complex medicines based on Eucalyptus globulus leaves and Cetraria islandica slan. These studies provide an opportunity for further development and standardization of extracts from these plants, and the main aim of this study is the development and standardization of a complex medicine. Materials and methods. Thin layer chromatography was used to determine the presence of these markers. Quantitative values of these biologically active substances were determined by spectrophotometric method according to the relevant methods of the State Pharmacopoeia of Ukraine. Results. Markers for the certification of Cetraria islandica and Eucalyptus globulus have been proposed in this study. Chlorophylls and 1,8-cineole were chosen as a marker for the study of Eucalyptus globulus, and polysaccharides were chosen as a marker for Cetraria islandica. The qualitative and quantitative content of these markers in the studied objects was studied. Further research in this direction will be aimed at developing methods for control and standardization of water and alcohol extracts from these plants. Conclusions. Biologically active substances in medicinal plant raw materials were studied. It is proposed to study extracts and finished products from Eucalyptus globulus leaves and Cetraria islandica slan using these methods. The method of qualitative and quantitative determination of polysaccharides in Cetraria islandica slan is easy to apply and easily reproducible. It is important to be able to standardize Eucalyptus globulus leaves for essential oils and chlorophylls. The biologically active substances-markers found in Eucalyptus globulus leaves and Cetraria islandica slan will be used for the development of herbal medicines, the standardization of which will be carried out for the same compounds

    Second-generation bioethanol from industrial wood waste of South American species

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    There is a global interest in replacing fossil fuels with renewable sources of energy. The present review evaluates the significance of South-American wood industrial wastes for bioethanol production. Four countries have been chosen for this review, i.e., Argentina, Brazil, Chile, and Uruguay, based on their current or potential forestry industry. It should be noted that although Brazil has a global bioethanol market share of 25%, its production is mainly first-generation bioethanol from sugarcane. The situation in the other countries is even worse, in spite of the fact that they have regulatory frameworks in place already allowing the substitution of a percentage of gasoline by ethanol. Pines and eucalyptus are the usually forested plants in these countries, and their industrial wastes, as chips and sawdust, could serve as promising raw materials to produce second-generation bioethanol in the context of a forest biorefinery. The process to convert woody biomass involves three stages: pretreatment, enzymatic saccharification, and fermentation. The operational conditions of the pretreatment method used are generally defined according to the physical and chemical characteristics of the raw materials and subsequently determine the characteristics of the treated substrates. This article also reviews and discusses the available pretreatment technologies for eucalyptus and pines applicable to South-American industrial wood wastes, their enzymatic hydrolysis yields, and the feasibility of implementing such processes in the mentioned countries in the frame of a biorefinery.Fil: Vallejos, María Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Kruyeniski, Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Area, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentin

    Atividade antimicrobiana do óleo de Eucalyptus globulus, xilitol e papaína: estudo piloto

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    OBJETIVO Avaliar a atividade antimicrobiana in vitro do √≥leo essencial de Eucalyptus globulus e das subst√Ęncias xilitol e papa√≠na, frente aos micro-organismos: Pseudomonas aeruginosa; Samonella sp.; Staphylococus aureus; Proteus vulgaris; Escherichia coli e Candida albicans. M√ČTODO Utilizou-se a avalia√ß√£o antimicrobiana in vitro, por meio do teste da difus√£o em √°gar e avalia√ß√£o do di√Ęmetro do halo de inibi√ß√£o das subst√Ęncias testadas. A clorexidina 0,5% foi utilizada como controle. RESULTADOS Observou-se que o √≥leo de Eucalyptus globulus apresentou inibi√ß√£o superior √† da clorexidina quando aplicado ao Staphylococus aureus, e inibi√ß√£o id√™ntica quando aplicado aos micro-organismos Escherichia coli, Proteus vulgaris e Candida albicans. A papa√≠na 10% apresentou efeito antimicrobiano inferior ao da clorexidina em rela√ß√£o √† Candida albicans. O xilitol n√£o apresentou inibi√ß√£o dos micro-organismos testados. CONCLUS√ÉO O √≥leo de Eucalyptus globulus possui atividade antimicrobiana contra diferentes micro-organismos e parece ser uma alternativa vi√°vel como agente germicida, portanto, recomendam-se novas investiga√ß√Ķes.OBJECTIVE To evaluate the in vitro antimicrobial activity of the Eucalyptus globulus essential oil, and of the xylitol and papain substances against the following microorganisms: Pseudomonas aeruginosa; Samonella sp.; Staphylococus aureus; Proteus vulgaris; Escherichia coli and Candida albicans. METHOD The in vitro antimicrobial evaluation was used by means of the agar diffusion test and evaluation of the inhibition zone diameter of the tested substances. Chlorhexidine 0.5% was used as control. RESULTS The Eucalyptus globulus oil showed higher inhibition than chlorhexidine when applied to Staphylococcus aureus, and equal inhibition when applied to the following microorganisms: Escherichia coli, Proteus vulgaris and Candida albicans. Papain 10% showed lower antimicrobial effect than chlorhexidine in relation to Candida albicans. Xylitol showed no inhibition of the tested microorganisms. CONCLUSION The Eucalyptus globulus oil has antimicrobial activity against different microorganisms and appears to be a viable alternative as germicidal agent hence, further investigation is recommended.OBJETIVO Evaluar la actividad antimicrobiana in vitro del aceite esencial de Eucalyptus globulus y las sustancias xilitol y papa√≠na, ante los microorganismos: Pseudomonas aeruginosa; Samonella sp.; Staphylococus aureus; Proteus vulgaris; Escherichia coli y Candida albicans. M√ČTODO Se utiliz√≥ la evaluaci√≥n antimicrobiana in vitro, por medio de la prueba de la difusi√≥n en agar y evaluaci√≥n del di√°metro del halo de inhibici√≥n de las sustancias probadas. La clorhexidina al 0,5% fue utilizada como control. RESULTADOS Se advirti√≥ que el aceite de Eucalyptus globulus present√≥ inhibici√≥n superior a la de la clorhexidina cuando aplicado al Staphylococus aureus, e inhibici√≥n id√©ntica cuando aplicado a los microorganismos Escherichia coli, Proteus vulgaris y Candida albicans. La papa√≠na al 10% present√≥ efecto antimicrobiano inferior al de la clorhexidina con relaci√≥n a la Candida albicans. El xilitol no present√≥ inhibici√≥n de los microorganismos probados. CONCLUSI√ďN El aceite de Eucalyptus globulus tiene actividad antimicrobiana contra diferentes microorganismos y parece ser una alternativa viable como agente germicida, por lo que se recomiendan nuevas investigaciones

    Growth and suitability of some tree species selected for planting in adverse environments in Eritrea and Ethiopia

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    The thesis addresses some important silvicultural issues raised in Eritrea and Ethiopia and the objective was to evaluate various tree species in terms of growth in adverse environments. Three field and two greenhouse studies were performed using the main species Eucalyptus globulus, Cordia africana, Casuarina cunninghamiana, and Acacia tortilis, A. nilotica and Leucaena leucocephala. Growth of E. globulus tree was influenced by altitude and stand density when assessed in a planted stand in Ethiopia. Decreasing altitude increased growth only up to the middle of the valley hillside. Increasing density increased growth. Soil depth had no impact on growth of E. globulus and this shows that the species is suitable for planting on shallow soils. Data from a C. africana spacing trial in Eritrea were analysed to improve the management of C. africana plantations established on degraded dry lands by evaluating the response of the species to various initial spacings. Planting C. africana trees at wider spacing can be advantageous in terms of growth, but not stem quality. Different provenances of C. cunninghamiana were tested in two field trials in Eritrea to identify the provenance matching marginal lands of the Eritrean highlands. For firewood and small pole production, the use of the fast growing provenances ‚ÄėCoonabarabran‚Äô (CN), ‚ÄėFlag stone‚Äô (FS), and ‚ÄėRollingstone‚Äô (RS) is recommended. However, the use and wide spread of the three provenances must be taken with caution due to the risks involved in the use of exotic tree species. Two greenhouse experiments investigated the suitability of A. tortilis for manure production and rehabilitating salt affected marginal lands. The species has a greater potential to produce mulch rich in nitrogen and phosphorus compared to L. leucocephala. Nevertheless, further research under field conditions would be needed to confirm the results and the sustainability of such a practice. A. tortilis and A. nilotica seem to be sensitive to salinity. However, because the two acacias have a wide distribution covering a large salinity gradient, there could be other provenances or ecotypes of both species that are more tolerant to salinity. Therefore, screening tests involving various genotypes of both species could be promising to find suitable trees for afforestation on salt affected soils in arid and semiarid Africa

    Biomass losses caused by Teratosphaeria leaf disease in Eucalyptus globulus short rotation forestry

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    This article presents the results of a study that examines the loss of biomass and energy, per hectare, caused by Teratosphaeria leaf disease (TLD) in Eucalyptus globulus short rotation forestry. The 95 Eucalyptus globulus taxa analyzed are from seeds of open pollinated families of both Spanish and Australian origin. Tree height and diameter were measured and the crown damage index (CDI) assessed at 27 months of age. Taxa that have a certain tolerance to the disease have been identified. The taxon identified as code 283 is the one that shows lower CDI (42%) and with an average volume that exceeded 0.017 m3 at 27 months of age. Biomass losses were determined for each fraction of dry biomass of the tree (leaves, branches, twigs and bark) based on CDI. These losses were translated into terms of energy lost per hectare, depending on the CDI. A comparison was then carried out between the productivity of Eucalyptus globulus exhibiting various levels of TLD severity and poplar and willow clones used for bioenergy in Europe. In our region, the results show that despite the losses of biomass associated with TLD, Eucalyptus globulus remains competitive as long as CDI values are lower than 56%

    Investigation of the chemocatalytic and biocatalytic valorization of a range of different lignin preparations: The importance of ő≤-O-4 content

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    A set of seven different lignin preparations was generated from a range of organosolv (acidic, alkaline, ammonia-treated, and dioxane-based), ionic liquid, autohydrolysis, and Kraft pretreatments of lignocelluloses. Each lignin was characterized by 2D HSQC NMR spectroscopy, showing significant variability in the ő≤-O-4 content of the different lignin samples. Each lignin was then valorised using three biocatalytic methods (microbial biotransformation with Rhodococcus jostii RHA045, treatment with Pseudomonas fluorescens Dyp1B or Sphingobacterium sp. T2 manganese superoxide dismutase) and two chemocatalytic methods (catalytic hydrogenation using Pt/alumina catalyst, DDQ benzylic oxidation/Zn reduction). Highest product yields for DDQ/Zn valorization were observed from poplar ammonia percolation-organosolv lignin, which had the highest ő≤-O-4 content of the investigated lignins and also gave the highest yield of syringaldehyde (243 mg L -1 ) when using R. jostii RHA045 and the most enzymatic products using P. fluorescens Dyp1B. The highest product yield from the Pt/alumina hydrogenation was observed using oak dioxasolv lignin, which also had a high ő≤-O-4 content. In general, highest product yields for both chemocatalytic and biocatalytic valorization methods were obtained from preparations that showed highest ő≤-O-4 content, while variable yields were obtained with preparations containing intermediate ő≤-O-4 content, and little or no product was obtained with preparations containing low ő≤-O-4 content

    High pressure pre-treatments promote higher rate and degree of enzymatic hydrolysis of cellulose

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    The effect of high pressure (HP) pre-treatments on the subsequent enzymatic hydrolysis of cellulose from bleached kraft Eucalyptus globulus pulp by cellulase from Tricoderma viride was evaluated. Pressure pre-treatments of 300 and 400 MPa during 5‚Äď45 min, lead to both an increased rate and degree of hydrolysis, reaching values ranging from 1.5- to 1.9-fold, quantified by the formation of reducing sugars. Both the pressure and time under pressure influenced the enzymatic hydrosability of the cellulosic pulps, with the former being more important. The results indicate that the pressure pre-treatments promoted an increased accessibility of cellulose towards cellulase in the cell wall. The results obtained open promising possibilities, to contribute to overcome conventional limitations of enzymatic cellulose hydrolysis for the production of fermentable glucose, for the production of second generation bioethanol and chemicals by enhancement of both rate and yield of hydrolysis. The results are also of interest for the preparation of ‚Äúpressure engineered‚ÄĚ celullose with incremented tailored hydrolysis patterns

    Natural durability assessment of thermo-modified young wood of Eucalyptus

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    This study focuses on the effect on wood strength and natural durability of Eucalyptus globulus and Eucalyptus botryoides when subjected to heat treatments with low energy consumption. The objective was to improve the wood durability, without negatively impacting the strength properties. Six-year-old trees from Eucalyptus globulus and Eucalyptus botryoides were used. The samples were heat treated for 4 h conditioned to very low oxygen availability. A field test for assessing the resistance to termites and fungal degradation was conducted according to EN 252:1989/ AC1:1989 Inspections were made every six months for 3 years. All the samples of Eucalyptus globulus showed signs of termite and microorganisms attack, most showing extensive galleries. Eucalyptus botryoides wood showed no sign of termite attack and only few traces of microrganisms presence. The wood bending strength was smaller upon thermal treatment for both species, decreasing 3.8% and 4.8% for Eucalyptus globulus and Eucalyptus botryoides, respectively. Overall the results are promising regarding some common utilizations, mainly floor coverings, decks, doors and door and window frames, fences (only for Eucalyptus botryoides), decorative arbors and pergolas (only for Eucalyptus botryoides) but excluding structural beams for building roofs or bridges due to the fragility of the wood treated thermally towards impactsinfo:eu-repo/semantics/publishedVersio
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