Thermally assisted hydrolysis and alkylation of lignins in the presence of tetra-alkylammonium hydroxides

Three different milled lignins isolated from bamboo, pine and beech, corresponding to the three different structural groups, have been subjected to pyrolysis in the presence of tetramethylammonium hydroxide (TMAH) and tetrabutylammonium hydroxide (TBAH). Pyrolysis of the lignins in the presence of TMAH releases the methyl esters and methyl ethers of the different lignin monomers. Several moieties bearing carboxylic acid groups, not previously detected using pyrolytic techniques, could be released from the three lignins, suggesting that the presence of these moieties in the lignin structure have been underestimated.The authors wish to thank the CICyT (Spanish Direction General de Investigation Cientifica y Tecnica; Project PB91-0074) for financial support.Peer Reviewe

Dinámica de sistemas, política económica y política monetaria

System Dynamics, Economic Policy, and Monetary Policy. The advances in the Systems Approach and its tools are, in our view, well-known and undeniable. Altogether, they possess a great capacity, both for the understanding of the complex reality of social systems, and for permitting computer-simulated experiments with a considerable degree of realism, at low cost and with little risk. However, traditional Economic Analysis would appear to be impervious to these advances, remaining for the most part within an analytical-reductionist framework at some distance from reality. In the present study, our aim is to use the Systems Approach, and within it the instrumentation offered by the conceptualization phase of System Dinamics modelling, in orderto inter-relate the various objectives of Economic Policy in Spain, and to relate these to Monetary Policy, whose objectives must be subordinated to the former. The transparency and clarity of this approach and its tools facilitate significantly an understanding of the complex economic reality of this country, representing, in our judgment, a powerful tool for the transmission and assimilation of knowledge in Economics.El avance experimentado por el Enfoque de Sistemas y sus instrumentos resulta, a nuestro juicio, notorio e indiscutible. El conjunto posee una gran capacidad, tanto para la comprensión de la compleja realidad de los sistemas sociales, como para permitir experimentos simulados en ordenador con un notable grado de realismo y con escaso coste y riesgo. Sin embargo, el Análisis Económico convencional parece permanecer impermeable a tales avances y se mantiene, por lo general, dentro de un marco analítico-reduccionista bastante alejado de la realidad. En el presente trabajo, pretendemos utilizar el Enfoque de Sistemas y, dentro de él, la instrumentación ofrecida por la fase de conceptualización del modelado con Dinámica de Sistemasl, para relacionar los distintos objetivos de la Política Económica en España y a éstos con la Política Monetaria, cuyas metas deben supeditarse a los primeros. La transparencia y claridad ofrecida por dicho enfoque y sus instrumentos facilitan, de forma importante, la comprensión de la compleja realidad económica de este país pudiendo constituir, a nuestro juicio, un potente utensilio para la transmisión y asimilación del conocimiento en Economía

Phenylphenalenone type compounds from the leadf fibers of abaca (Musa textilis)

1Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, P.O. Box 1052, E-41080, Seville, Spain 2Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain 3Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán, 04510 México D. F., MéxicoA series of phenylphenalenone–type compounds, known to play a role as phytoalexins in plants of the Musaceae family, have been identified for the first time in the leaf fibers of abaca (Musa textilis). Among the phenylphenalenone-type compounds identified, the structure of a novel compound, (1R) -2,3-dihydro-4,9-dihydroxy-8-methoxy-1-phenylphenalene, has also been described in abaca fibers. Its structure was elucidated by analysis of 1D- and 2D-NMR (COSY, HSQC, HMBC) spectroscopic data.Financial support from the project AGL2005-01748.Peer reviewe

Chemical characterization of lignin and lipophilic fractions from leaf fibers of curaua (Ananas erectifolius)

E-mail: [email protected] (J.C. del Río)The chemical composition of leaf fibers of curaua (Ananas erectifolius), an herbaceous plant native of Amazonia, was studied. Special attention was paid to the content and composition of lignin and lipophilic compounds. The analysis of lignin in the curaua fibers was performed “in situ” by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and showed a lignin composition with a p-hydroxyphenyl:guaiacyl:syringyl units (H:G:S) molar proportion of 30:29:41 (S/G molar ratio of 1.4). The presence of p-hydroxycinnamic acids (p-coumaric and ferulic acids) in curaua fibers was revealed upon pyrolysis in the presence of tetramethylammonium hydroxide. On the other hand, the main lipophilic compounds, analysed by GC/MS, were series of long-chain n-fatty acids, n-fatty alcohols, α- and ω-hydroxyacids, monoglycerides, sterols and waxes. Other compounds, such as ω-hydroxy monoesters and ω-hydroxy acylesters of glycerol were also found in this fiber in high amounts.Peer reviewe

Oxidative modification of paper pulp lipophilic extractives by laccase-mediator system

Recently, we have shown the effectiveness of the laccase-mediator system in removing lipophilic extractives from pulp regardless the pulping process and the raw material used. This paper summarizes our research findings on the chemistry of the reactions of the main lipophilic extractives present in paper pulps with the laccase-mediator system. The results attained in reactions of several model lipids - including alkanes, fatty alcohols, fatty acids, resin acids, free sterols, sterol esters and triglycerides - with a fungal laccase in the presence of HBT as mediator, are discussed in the context of enzymatic control of pitch deposits, to explain the removal of complex lipid mixtures during laccase-mediator treatment of different pulp types, including eucalypt pulp.This study was funded by the BIORENEW EU-project (NMP2-CT-2006-026456) and the Spanish MICINN (AGL-2008-00709). Beldem (Andenne, Belgium) is acknowledged for laccase supply. S. Molina and J. Rencoret are acknowledged for their contribution to this work.Peer reviewe

Chemical composition of lipophilic extractives from non-woody plants used for manufacturing high-quality papers

The chemical composition of lipophilic extractives from fibers of three annual plants, namely hemp (Cannabis sativa), flax (Linum usitatissimum) and kenaf (Hibiscus cannabinus) that are commonly used for high quality paper pulp production was studied. The cloroform soluble fractions of the acetone extracts of the fibers were analyzed by gas chromatography-mass spectrometry. The main compounds identified were series of n-alkanes, n-fatty acids, n-aldehydes, n-fatty alcohols and waxes. On the other hand, free and esterified sterols and triterpenols, steroid hydrocarbons, steroid and triterpenoid ketones, as well as sterol glycosides were also found in the fibers studied here.A.G. acknowledges a "Ramón y Cajal" contract of the Spanish MCYT. We thank CELESA (Tortosa, Spain) for providing the raw materials.Peer reviewe

Chemical composition of lipophilic extractives from sisal (Agave sisalana) fibers

Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, PO Box 1052, E-41080 Seville, Spain. Corresponding author, E-mail: [email protected] (A. Gutiérrez)The chemical composition of lipophilic extractives from sisal (Agave sisalana) fibers, which are used for high-quality paper pulp production was studied. The lipophilic extract, which accounted for 0.5 % of total sisal fiber weight, was analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) using short- and medium-length high temperature capillary columns, respectively. For a more detailed characterization, the extract was fractionated by solid-phase extraction and the fractions obtained were analyzed by GC and GC/MS. The most predominant compounds identified were fatty acids (30% of total lipids) including α- and -hydroxyfatty acids, fatty alcohols (20%), free sterols (11%), alkanes (11%) and a series of ferulic acid esters of long chain alcohols and -hydroxyfatty acids (10%). Additionally, steroid hydrocarbons and ketones, monoglycerides, aldehydes, waxes, and sterol glycosides were also found together with minor amounts of diglycerides, and sterol esters.This study has been supported by the Spanish Ministerio de Ciencia y Tecnología (MCYT) (projects AGL2002-00393 and AGL2005-01748) and EU project (BIORENEW, NMP2-CT-2006-026456). We thank CELESA pulp mill (Tortosa, Spain) for providing the sisal fibers.Peer reviewe

Isolation and structural characterization of the acetylated heteroxylan from sisal (Agave sisalana) and its fate during alkaline pulping and TCF/ECF bleaching.

The heteroxylan from sisal, an O-acetyl-(4-O-methylglucurono)xylan with a molecular weight (Mw) of 18 kDa, was isolated by extraction of peracetic holocellulose with Me2SO and thoroughly characterized by wet chemistry, and NMR spectroscopy. The heteroxylan backbone is composed of (1→4)-linked β-D-xylopyranosyl units (Xylp) partially ramified with terminal (1→2)-linked 4-O-methyl-α-D-glucuronosyl (MeGlcpA) and a small proportion of α-D-glucuronosyl (GlcpA) residues. Roughly 61mol% of Xylp residues are acetylated (DS =0.70). During soda/AQ pulping, GlcpA and MeGlcA are partially removed or converted to 4-deoxy-β-L-threo-hex-4-enopyranosyluronic acid (HexA), though notable proportion of GlcpA maintained intact. The major part of acetyl groups was hydrolyzed during pulping. It was proposed that the predominantly low molecular weight xylan fraction was removed from pulp during bleaching. The profiles of uronosyl residues in xylans from TCF and ECF bleached sisal pulps were rather different.This study has been supported by the Spanish MEC (Project AGL2005-01748) and EU Contract NMP2-CT-2006-26456. We thank CELESA (Tortosa, Spain) for providing the samples. G.M. thanks the Spanish Ministry of Education for a FPI fellowship.Peer reviewe

Influence of aspirin therapy in the ulcer associated with chronic venous insufficiency

Producción CientíficaBackground: To determine the effect of aspirin on ulcer healing rate in patients with chronic venous insufficiency, and to establish prognostic factors that influence ulcer evolution. Methods: Between 2001 and 2005, 78 patients with ulcerated lesions of diameter >2 cm and associated with chronic venous insufficiency were evaluated in our hospital. Of these, 51 patients (22 men, 29 women) with mean age of 60 years (range: 36e86) were included in a prospective randomized trial with a parallel control group. The treatment group received 300 mg of aspirin and the control group received no drug treatment; in both groups, healing was associated with standard compression therapy. During follow-up, held weekly in a blinded fashion, there was ulcer healing as well as cases of recurrence. Results were analyzed by intention-to-treat approach. Cure rate was estimated using KaplaneMeir survival analysis, and the influence of prognostic factors was analyzed by applying the Cox proportional hazards model. Results: In the presence of gradual compression therapy, healing occurred more rapidly in patients receiving aspirin versus the control subjects (12 weeks in the treated group vs. 22 weeks in the control group), with a 46% reduction in healing time. The main prognostic factor was estimated initial area of injury (P ¼ 0.032). Age, sex, systemic therapy, and infection showed little relevance to evolution. Conclusions: The administration of aspirin daily dose of 300 mg shortens the healing time of ulcerated lesions in the chronic venous insufficiency (CVI). The main prognostic factor for healing of venous ulcerated lesions is the initial surface area of the ulcer

Biomarkers in the bitominous fraction of a spanish brown coal

8 pages, 5 figures, 2 tables, 19 references.Molecular indicators such as diterpenoid and triterpenoid hydrocarbons and steroid alcohols and ketones have been identified in the bituminous fraction of the lignite from Arenas del Rey (AR), South Spain. Diterpenoid hydrocarbons consists mainly of kaurenes and are indicati ve of higher plant contributions, specially from conifer resins. Triterpenoids consist mainnly of 17beta(H),21beta{H)-hopanes derived from recent biogenic activity which indicates the geological immaturity of this lignite and implies that it has undergone only a mild thermal history. Sterols consist of cholesterol, carmpesterol, stigmasterol and beta-sitosterol and their distribution suggests a possible phytoplankton input, which should confirm the geological hypothesis that this sediment had an estuarine or deltaic origin. Occurrence of stanones with the biological 5alfa configuration was also observed.Peer reviewe