Green Additives in Chitosan-based Bioplastic Films: Physical, Mechanical, and Chemical Properties

To switch to alternatives for fossil-fuel-based polymer materials, renewable raw materials from green resources should be utilized. Chitosan is such a material that is a strong, but workable derivative from chitin, obtained from crustaceans. However, various applications ask for specific plastic properties, such as certain flexibility, hardness and transparency. With different additives, also obtainable from green resources, chitosan-based composites in the form of self-supporting films, ranging from very hard and brittle to soft and flexible were successfully produced. The additives turned out to belong to one of three categories, namely linear, non-linear, or crosslinking additives. The non-linear additives could only be taken up to a certain relative amount, whereas the uptake of linear additives was not limited within the range of our experiments. Additives with multiple functional groups tend to crosslink chitosan even at room temperature in an acidic medium. Finally, it was shown that dissolving the chitosan in acetic acid and subsequently drying the matrix as a film results in reacetylation compared to the starting chitosan source, resulting in a harder material. With these findings, it is possible to tune the properties of chitosan-based polymer materials, making a big step towards application of this renewable polymer within consumer goods

Azolla domestication towards a biobased economy?

Brouwer P, Bräutigam A, Külahoglu C, et al. Azolla domestication towards a biobased economy? New Phytologist. 2014;202(3):1069-1082.Due to its phenomenal growth requiring neither nitrogen fertilizer nor arable land and its biomass composition, the mosquito fern Azolla is a candidate crop to yield food, fuels and chemicals sustainably. To advance Azolla domestication, we research its dissemination, storage and transcriptome. Methods for dissemination, cross-fertilization and cryopreservation of the symbiosis Azolla filiculoides-Nostoc azollae are tested based on the fern spores. To study molecular processes in Azolla including spore induction, a database of 37649 unigenes from RNAseq of microsporocarps, megasporocarps and sporophytes was assembled, then validated. Spores obtained year-round germinated in vitro within 26d. In vitro fertilization rates reached 25%. Cryopreservation permitted storage for at least 7months. The unigene database entirely covered central metabolism and to a large degree covered cellular processes and regulatory networks. Analysis of genes engaged in transition to sexual reproduction revealed a FLOWERING LOCUS T-like protein in ferns with special features induced in sporulating Azolla fronds. Although domestication of a fern-cyanobacteria symbiosis may seem a daunting task, we conclude that the time is ripe and that results generated will serve to more widely access biochemicals in fern biomass for a biobased economy

Utilización de Pirolisis con Cromatografía de Gases y Espectrometría de Masas (Py-GC/MS) para el estudio de la composición química de la materia orgánica de un suelo mediterráneo sometido a diferentes temperaturas

Ponencia presentada en el Seminario de Evaluación de Procesos de Degradación de Suelos: Problemas Metodólogicos celebrado en Lleida del 14 al 16 de julio de 2010Los incendios forestales se pueden considerar como una de las principales alteraciones de los suelos y la vegetación de la cuenca del Mediterráneo (Rubio et al., 1996; Andreu et al., 2001). Uno de los principales efectos de los incendios forestales en las propiedades del suelo es la alteración de la materia orgánica (SOM), afectando tanto a su contenido como a su composición (González-Pérez, 2004; Knicker, 2007). El estudio de los cambios en la composición de la SOM ha avanzado sustancialmente gracias a la utilización de técnicas tales como la resonancia magnética nuclear (NMR), la pirólisis con cromatografía de gases y espectrometría de masas (Py-GC/MS), la hidrólisis y metilación asistida térmicamente (THM), etc. (González-Vila et al., 2001; Nierop et al., 2001). La Py-GC/MS es un enfoque alternativo que consiste en la degradación térmica de las moléculas orgánicas en fragmentos pequeños que son analizados por GC/MS, suministrando información relacionada con su estructura, la cual puede ser utilizada para el estudio de las alteraciones térmicas de la materia orgánica. Los productos de pirólisis de suelos sin quemar incluyen una amplia variedad de moléculas derivadas de carbohidratos, lignina, lípidos y proteínas. Por el contrario, en suelos afectados por incendios forestales, la mayoría de los productos de pirólisis presentes en los suelos no quemados están ausentes y el dominio del material del tipo carbonoso refractario quemado ¿no-pirolisable¿ es evidente (González-Pérez et al., 2004). Los objetivos del presente trabajo son: (a) Explorar las posibles diferencias en la caracterización química de la SOM en los macro y microagregados de un suelo mediterráneo bajo planta y otro desnudo, y (b) investigar los efectos del impacto de diferentes temperaturas en los compuestos derivados de la materia orgánica procedente de estas fracciones en dichos suelos.Peer Reviewe

Strengthening the soil organic carbon pool by increasing contributions from recalcitrant aliphatic bio(macro)molecules

Photosynthetically fixed CO2 is converted into terrestrial bio(macro)molecules and sequestered as soil organic matter (SOM) by (bio)chemical and physical stabilization processes. SOM is generally divided in arbitrary pools for modeling SOM dynamics. Biochemically recalcitrant SOM fractions are enriched with alkyl carbon (C) structures and resist decomposition due to intrinsic molecular properties. The proportion of alkyl C and the mean age of SOM increase with increase in soil depth. Precursors of these recalcitrant bio(macro)molecules such as glycerides, waxes, and terpenoids occur in plants, microorganisms and animals. The intrinsic biochemical stability of naturally occurring recalcitrant aliphatic biomacromolecules may enhance the terrestrial storage of atmospheric CO2. Also, aliphatic macromolecules may be formed in soils upon non-enzymatic polymerization of low-molecular-weight lipids. In this review we propose that increasing the soil organic carbon (SOC) pool by land-use and management practices should also include strategies to increase the proportion of aliphatic compounds in the belowground biomass. Thus, collaborative research is needed to study the fate of plant-, microbial- and animal-derived aliphatic C as precursors for stabilized aliphatic SOC fractions, in particular in deeper soil horizons

Copper complexation by dissolved organic matter and uncertainty assessment of their stability constants. Chemosphere 2002

Abstract The interaction of Cu with dissolved organic matter (DOM, extracted from an organic forest floor) was investigated and the resulting data was evaluated in terms of their uncertainty. The speciation of Cu over ÔfreeÕ Cu (as analysed by diffusive gradients in thin films (DGT)), dissolved Cu-DOM complexes and precipitated Cu-DOM was determined as a function of pH (3.5, 4.0 and 4.5) and Cu/C ratio. The dissolved organically bound fraction was highest at pH 4.5, but this fraction decreased with increasing Cu/C ratio, which was observed for all pH levels. In the range of Cu=C ¼ 7 Â 10 À5 -2:3 Â 10 À2 (mol/mol) the precipitated fraction was very small. The speciation of both Al and Fe was not affected by increasing Cu concentrations. From a continuous distribution model using the Scatchard approach, we calculated the optimal fit and corresponding upper and lower 95% uncertainty bounds of the overall stability constants (K o ) with the shuffled complex evolution Metropolis (SCEM) algorithm. Although the optimal equation fitted the data very well, the uncertainty of the, according to literature, most reliable approach to establish stability constants, was still large. Accordingly, the usually reported intrinsic stability constants exhibited large uncertainty ranging from log K i ¼ 6:0-7.1 (optimal 6.7) for pH 3.5, log K i ¼ 6:5-7.1 (optimal 6.8) for pH 4.0, and log K i ¼ 6:4-7.2 (optimal 6.8) for pH 4.5 and showed only little effect of pH

Contribution of organic matter molecular proxies to interpretation of the last 55ka of the Lynch's Crater record (NE Australia)

The Lynch's Crater (NE Australia) deposit is a key information source on Late-Quaternary palaeoenvironmental change, including human-induced deforestation since the arrival of Aboriginals, megaherbivore extinction and southern hemisphere tropical climate dynamics. This study adds to the important dataset available for the site by assessing the molecular composition of organic matter in the record using pyrolysis-GC-MS to elucidate ecological and hydrological conditions since 55. ka BP.Pyrolysates were dominated by methylene chain compounds (MCCs) and lignin products (methoxyphenols). Concomitant increases in MCCs and aquatic source indicators (biogenic opaline silica, Si:Al ratio, SEM-visible debris of sponges and diatoms and aquatic pollen taxa), which roughly coincide with abrupt climate events in GISP2 δ18O (Heinrich event H3, H1, 8.2ka and oscillations at 33-36ka BP), reflect transitions from peat (dominated by lignin from terrestrial plants) to lacustrine (MCCs from aquatic plants) conditions. The evidence points towards wet conditions causing the accumulation of layers rich in inorganic sediment during H events, favouring the hypothesis of a southward ITCZ shift, rather than an ENSO-induced northward shift, as the underlying mechanism. This contradicts previous studies using the >degree of peat humification> index (DPH). We measured DPH and the extracts and residues by PY-GC-MS, to better understand the validity of this surface moisture proxy. Paradoxically, high DPH corresponds to the relatively young (<15ka) ombrotrophic peat environment, as DPH relies on the proportion of extractable carbohydrates concentrated in this part of the core, while deeper and unarguably more evolved layers are comprised of alkali-inextricable lignin and MCCs. Therefore, DPH does not accurately reflect humidity-controlled degradation/preservation dynamics and its use for studying climate change in complex records, such as Lynch's Crater, is cautioned. Finally, the decoupling of humidity conditions from changes in regional arboreal vegetation supports the hypothesis of an anthropogenic- rather than climate-driven shift towards sclerophyllous vegetation since 45ka, but the hydroseral complexity of the system demands caution on this matter. © 2014 Elsevier B.V.This research was supported by the CONSOLIDER-INGENIO 2010 program CSD2007-00058 on “Technology for cultural heritage preservation” and Plan Nacional I + D + iCGL2010-20672 on “Peat response to Late-Pleistocene and Holocene climate change in the boreal, temperate and tropical zones”, of the Spanish Ministry of Science and Education.Peer Reviewe